Dissertations / Theses: 'Human endogenous retroviruse'

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DOLCI, MARIA. "UNRAVELING THE ROLE OF THE HUMAN ENDOGENOUS RETROVIRUSES IN THE PATHOGENESIS OF COLON CANCER." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/703397.

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Background: Human endogenous retroviruses (HERV) are remnants of exogenous retroviral infections, representing 8% of the human genome. Their regulation is based on the DNA methylation of promoters, the long terminal repeats (LTRs). Transcripts from HERV have been associated with cancers, but reports concerning HERV expression in colorectal cancer remain sporadic. Methods: 63 Italian patients and 58 Tunisian patients with advanced stages of colorectal cancer were enrolled in this study. HERV-H, -K, -R, -P LTRs, and Alu, LINE-1 methylation levels, and the expressions of HERV env and pol gene were investigated by pyrosequencing and by RT qPCR, respectively, in the tumor, normal adjacent tissues, and, when possible, in the blood and plasmatic extracellular vesicles (EVs). Associations among clinical characteristics and HERV expression and methylation levels were also evaluated. The expression of the HERV-K Pol/Env proteins was also evaluated by Western Blot. Results: As for the Italians patients, Alu, LINE-1, HERV-H and -K LTRs were demethylated in the tumor tissues compared to the normal adjacent tissues (p<0.05), while no differences were observed in HERV env gene expression levels, among the clinical specimens. The env gene was expressed in the EVs (p<0.01) of 54% (-H), 38% (-K), 31% (-R) patients. Associations were found between HERV expression and right tumor colon location and between HERV methylation and vascular invasion (p<0.05). HERV K Pol protein was more expressed (p<0.01) in the adjacent normal tissues compared to the tumor tissues. The Env protein was only expressed in the tumor tissue. As for the Tunisian population, LINE-1 was less methylated in the tumor tissue compared to the adjacent normal tissue (p<0.05), while Alu, HERV-K and -H LTRs showed the same trends, but the difference was not significant. The expression of the HERV env and pol genes were similar in the biological samples. No association was found between the HERV expression/methylation and the clinical characteristics of the Tunisian patients. Conclusions: The changes in DNA methylation of retroelements are specific in colorectal cancer but do not correlate with viral overexpression. The Pol protein expression in the normal cells may induce the retrotrascription and the subsequent transfer of HERV sequences into other cells, possibly through EVs. HERV genome insertion might cause cells transformation. In the cancer cells, the Env protein may contribute to the cancer progression through cell to cell fusion.

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Katzourakis, Aris. "The evolution of human endogenous retroviruses." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497642.

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Muir, Alison. "Placental expression of human endogenous retroviruses." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616115.

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Akleh, Rana Elias. "Developing a Single-Cycle Infectious System to Study an ERV-K Retroviral Envelope." Thesis, Boston College, 2017. http://hdl.handle.net/2345/bc-ir:107695.

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Thesis advisor: Welkin Johnson
Endogenous Retroviruses (ERVs) are “fossilized” retroviruses of a once exogenous retrovirus located in the genome of extant vertebrates. Retroviral infection results in a provirus integration into the host genome. An infection of a germline cell could lead to the provirus potentially being inherited by the offspring of the infected individual. Once in the genome, the provirus becomes subject to evolutionary processes and can become either lost or fixed in a population, remaining as “fossils” long after the exogenous retrovirus has gone extinct23. Notably, 8% of the human genome consists of ERVs30. Human Endogenous Retrovirus Type K (HERV-K)(HML-2) family is of particular interest. HERV-K integrations are as old as 30-35 million years, endogenizing before the separation of humans and Old World Monkeys. However, there are human specific insertions, some as young as 150,000 – 250,000 years, making them the youngest insertion in the human genome. There are over 90 insertions in the human genome; the bulk is shared by all humans44,47. Transcripts of HERV-K genes are upregulated in multiple cancer and tumor cell lines 14,39,46, as well as in HIV-1 infected patients 7,11,29. Just as there are human specific insertions of ERV-K, there are also Old World Monkey specific insertions44. I have identified an intact endogenous retroviral envelope open reading frame on chromosome 12 of the rhesus macaque genome. This viral envelope-encoding sequence, which I refer to as rhERV-K env, retains all the canonical features of a retroviral Env protein. An alignment between rhERV-K env and a consensus sequence of HERV-K, HERV-Kcon env, shows a 70% amino acid sequence identity. For experimental purposes, reconstructed HERV-K envelopes have been incorporated into virions of Human Immunodeficiency virus (HIV-1)19,26,49, Murine Leukemia Virus (MLV)12, and Vesicular stomatitis Virus (VSV)26,41,49. While these approaches have illuminated some aspects of HERV-K Env-mediated entry, to date a cell-surface receptor has not been identified for any ERV-K Env. This could be due to its low infectivity levels12,26,49, its seemingly broad cell tropism limiting identification of null cell lines26,49, or possibly the HERV-K consensus reconstructions are not an accurate representation of the progenitor HERV-K virus. I am interested in understanding how the ERV-K retrovirus accessed the human germline (some 150,000 – 250,000 years ago). To do this, I focused specifically on the envelope proteins of HERV-K and rhERV-K, with the goal of analyzing the ERV-K entry process. The identification and inclusion of rhERV-K Env in this study is meant to circumvent the possibility that the previously described consensus reconstructions of human HERV-K Env are not representative, and may also provide a means to compare the endogenization process in the human/ape and old-world monkey lineages. I focused on developing two systems for single-cycle infection, one based on Mason-Pfizer Monkey Virus (MPMV) (which has not been done before), and a second based on MLV, which has previously been reported on. MPMV, like HERV-K, is a betaretrovirus, and I reasoned that possibly using a betaretrovirus would overcome some of the low-infectivity issues associated with prior attempts using HIV and MLV. To develop a system for examining function of the ERV-K Env proteins, I addressed 3 issues: 1. Are the HERV-K Env and rhERV-K Env proteins expressed and properly processed? 2. Can they be incorporated into virions of a heterologous virus? 3. Are ERV-K pseudotyped virions infectious? I have answered these questions in the following thesis
Thesis (MS) — Boston College, 2017
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Biology

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Singh, Manvendra [Verfasser]. "Human endogenous retroviruses aid embryonic development / Manvendra Singh." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1181097703/34.

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Forrest, Graham Robert. "Human endogenous retrovirus 3 : evolutionary conservation and function." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312093.

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Hu, Lijuan. "Endogenous Retroviral RNA Expression in Humans." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Universitetsbiblioteket [distributör], 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8213.

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Kowalski, Paul Edward. "Novel genetic effects of a human endogenous retrovirus insertion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34571.pdf.

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Singh, Sarita. "Human endogenous retrovirus K gene expression in cutaneous melanoma." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/10118.

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Introduction: In recent years, the key environmental and genomic changes that "drive" melanoma have become more clearly elucidated but much remains to be understood. Data published in 2003 demonstrated expression of Human Endogenous Retrovirus K (HERV-K) in melanomas but not in normal tissues, indicating a potential oncogenic role. Furthermore, HERV-K proviruses encode the putative oncogenic proteins Rec and Np9. In this work the feasibility of reliable detection of HERV-K expression from formalin-fixed paraffin-embedded (FFPE) tissue has been determined. Expression has been correlated with melanoma subtype and histological markers of poor outcome. Methods: HERV-K mRNA expression in melanoma cell lines (A375 and WM2664), FFPE primary melanoma (n=39), normal skin (n=31) and benign naevus (n=16) tissues was investigated by a novel real-time quantitative RT-PCR (qRT-PCR). Expressed HERVK env sequences were cloned and sequenced. Results: A375 cells expressed all HERV-K genes and produced putative viral particles. Full-length mRNA was expressed in all primary melanoma and control tissues investigated with no differences in expression levels between the groups (pol: n=47, p=0.267; unspliced env: n=40, p=0.823). No correlation was observed with melanoma subtype or stage (Breslow). A proportion of all tissue types expressed np9 with no differences in expression levels between them (p=0.964). Spliced env was expressed in 8/39 melanoma, compared with 1/16 benign naevus and 0/31 normal skin samples (p=0.003). Expression of rec was found in 9/39 melanomas but not in control samples (p=0.009) nor extra-lesional skin in five rec-positive cases (p=0.06). The rec-positive melanomas were histologically in vertical growth phase and thicker than rec-negative tumours (median Breslow 2.1mm versus 1.05mm, p=0.009). Sequencing of expressed env cDNA clones derived from melanoma and control samples (n=8) revealed expression of multiple HERV-K loci. Conclusions: Gene expression can be studied in FFPE tissue. The expression of potentially oncogenic rec in approximately 25% primary melanomas merits further evaluation.

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Al-Shamarti, Ibtihal I. A. "Epigenetic dynamics of Human Endogenous Retroviruses (HERVs) in human cancer cell lines." Thesis, University of Leicester, 2018. http://hdl.handle.net/2381/42767.

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Transposable elements (TEs) are endogenous components of eukaryotic genomes, constituting 45% of human DNA. The human genome project revealed that human endogenous retroviruses (HERVs) constitute about 8% of the sequence. HERVs are derived from sequences integrated into germ cells during retrovirus infections, up to 25 million years ago. However, most copies of HERVs are defective in multiple ways. The HERV-K family is the youngest family and likely has significant biological activity because of its protein coding capacity. HERV-K activity may be involved in a variety of cancers, and in particular may play an important role in human melanoma. In this project, HERV activity in melanoma and different cancer cell lines was investigated. Our results showed the HERV-K pol gene is expressed in melanoma and in breast, prostate and colon cancers. Furthermore, the response to serum starvation conditions is not simply related to increased expression of HERV-K genes, and changes in cellular phenotype under serum starvation are limited to particular melanoma cell lines, rather than being a general phenomenon. HERV-K env protein expression in melanoma cells was compared to normal primary melanocytes - 1% FBS serum starvation can increase expression of this protein in SKMel5 cells that retain an adherent phenotype. Moreover, env protein expression is significantly increased in T47D breast cancer cells under 1% FBS. The analysis of HERV-K LTR methylation state demonstrated that HERV K env and gag proteins in melanoma cells under 10% FBS and 1% FBS conditions decreased. The most interesting finding was the detection of 98 candidate loci as novel proviral insertions where previously these loci were annotated as solo LTRs. This result suggests that proviruses are systematically excluded from assemblies and the census of HERV-K proviruses is much greater than represented in assembled genomes. The Genome-wide amplification of proviral sequences combined with Next Generation Sequences (GAPS –NGS) is established as an effective approach to discover new proviral loci.

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Patience, Clive. "Studies of endogenous retrovirus expression in human and pig cells." Thesis, Institute of Cancer Research (University Of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300308.

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Andersson, Ann-Catrin. "Studies on Human Endogenous Retroviruses (HERVs) with Special Focus on ERV3." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2002. http://publications.uu.se/theses/91-554-5342-2/.

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Zsíros, József. "Detection and analysis of HERV-K related endogenous retroviruses in the human genome." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/81502.

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Moore, Richard. "The study of retroviral sequences in human leukaemia." Thesis, Open University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367996.

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VARGIU, LAURA. "Characterization of Human Endogenous Retrovirus sequences identifed in the human genome using the RetroTector software." Doctoral thesis, Università degli Studi di Cagliari, 2014. http://hdl.handle.net/11584/266463.

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Human Endogenous Retroviruses (HERVs) represent the inheritance of ancient germ-line cell infections by exogenous retroviruses and the subsequent transmission of the proviral integrated elements to the descendants. Actually, no replication-competent HERV sequence is recognizable in the human genome. However, some HERVs retain one or several intact retroviral genes and may express protein products that could interfere with the human immune system. The number and classification of HERVs vary according to method of enumeration. The focus of this project is to perform a systematic analysis and a classification of the most intact HERV sequences in order to better understand their evolution and their involvement in shaping the human genome. The human genome assembly GRCh 37/hg19 was analyzed with RetroTector software and a total of 3290 HERV proviral sequences were identified. The complex genetic structure of the 3290 proviruses was resolved through a multi-step classification procedure that involved a novel type of similarity image analysis (Simage). The 3290 HERV were classified in 40 unique clades (groups) which could be placed into class I (Gamma- and Epsilon-like), II (Beta-like) and III (Spuma-like). Simage analysis contributed to define the presence of a high number (around 40%) of mosaic forms, with heterogenous sequence content. A finest characterization of the HERV sequences was achieved with the investigation of a broad panel of structural markers that contributed to confirm and extend the previously performed classification. Finally, the HERV background of integration was also studied. Integration patterns analysis showed a tendency for proviruses from the same clade to occur together, within 100000 bases, maybe due to local duplications. Representatives from some gammaretroviral clades (HERVH and HERVE) integrated more frequently than expected by chance into the 5´end of transcriptional units, mostly in antisense orientation. A few lncRNAs were also found to contain HERV sequences. Thus, cis-effects from HERVs are to be expected. In conclusion, this study represents an advance in the state-of-the art of HERV characterization within the human genome and a starting point for upcoming studies on HERVs.

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Tie, Christopher Hieng Chie. "Epigenetic control of endogenous retroviruses and their immune recognition in differentiated human cells." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10038410/.

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Endogenous retroviruses (ERVs) have accumulated in vertebrate genomes and contribute to the complexity of gene regulation. ERVs are beneficial to their hosts because their promoters can drive temporal and spatial expression of cellular genes. Aberrantly activated ERVs, however, can be detrimental. ERV transcription is therefore controlled by multiple epigenetic modifiers. One ERV repression pathway involves KAP1 and Krüppel-associated box domain-zinc finger proteins (KZNFs), which recruit KAP1 to ERVs and other repetitive sequences early in development. Little is known, in contrast, about the regulation of ERVs in differentiated cells, particularly in humans. In this thesis, we aimed firstly to address the question of whether KAP1 and related epigenetic factors are necessary to repress ERVs in differentiated human cells. Secondly, we sought to assess the impact of ERV reactivation on the innate immune system. We found through KAP1 knockout and mRNA-sequencing analyses that KAP1 represses ERVs and ZNFs, both of which overlap with KAP1 binding sites and silent chromatin marks in multiple cell types. Furthermore, this pathway is functionally conserved in primary human peripheral blood mononuclear cells (PBMCs). We show that cytosine methylation that acts on KAP1-regulated loci is necessary to prevent immune reactivity of ERVs and other retrotransposons that can mimic viruses by producing immunostimulatory nucleic acids. While KAP1 depletion alone leads to activation of several chemokines, it is not sufficient for global induction of interferon-stimulated genes. Therefore, we depleted key epigenetic complexes that KAP1 collaborates with including the HUSH complex comprising MPP8, Periphilin and Tasor. We identified MPP8 to play a dominant role in preventing aberrant immune activation in human cells. MPP8 is a chromodomain protein implicated in the spread of heterochromatin. In sum, these data indicate that the KAP1-KZNF pathway and MPP8 are central to genome stability and the control of viral mimicry in differentiated human cells.

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Yi, Joo-Mi. "Molecular genetic analysis of human endogenous retroviruses (HERVs) in primates : Expression, evolution, and phylogeny." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/145477.

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Rigogliuso, Giuseppe [Verfasser]. "Analyses of human endogenous retrovirus-encoded proteins with potential relevance for human biology and diseases / Giuseppe Rigogliuso." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2020. http://d-nb.info/122534915X/34.

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AL, DOSSARY REEM. "Activation of human endogenous retrovirus K and cellular modifications in human melanoma cell lines: gene expression analysis." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1389.

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Presso i laboratori dell’Università di Tor Vergata è stato sviluppato un sistema in vitro dotato di caratteristiche idonee allo studio dei meccanismi che sono alla base dello sviluppo e della progressione del melanoma. Tale sistema è costituito da una linea cellulare di melanoma umano, isolata da una lesione metastatica di una paziente e caratterizzata dalla capacità di crescere in adesione (linea TVM-A12), da cui sono state ottenute due distinte linee cellulari, dotate invece della caratteristica di crescita in sospensione, derivate l’una mediante tecnica della diluizione limite (Clonesp), e l’altra riducendo la concentrazione di siero dal 10% al 1% nel terreno di coltura (linea TVM-A12sp). Il passaggio dalla fase di crescita in adesione a quella in sospensione, osservato quando le cellule TVM-A12 erano poste in condizione di ridotta concentrazione di siero (1%) era accompagnato da riduzione di espressione dell’antigene melanocitico Melan-A/MART-1 e delle molecole HLA di classe I oltre che dall’aumentata capacità di formare colonie in terreno semisolido. Il cambiamento nella modalità di crescita delle cellule risultava inoltre associata all’aumento dell’espressione di HERV-K, sia a livello di mRNA che di proteine e poteva essere inibito dal blocco dell’espressione di HERV-K, ottenuto mediante RNA interference. Scopo del presente lavoro è stato quello di caratterizzare le linee cellulari TVM-A12, parentale e di derivazione, dotate rispettivamente di capacità di crescita in aderenza ed in sospensione, al fine di chiarire i meccanismi che sono alla base dell’acquisizione del fenotipo dotato di maggiore aggressività ed individuare il ruolo dell’attivazione di HERV-K nella progressione del melanoma. A tale scopo, è stato condotto uno studio dell’espressione genica, mediante microarray, seguito da analisi in Real-Time PCR, che ha mostrato come la transizione fenotipica delle cellule, dalla fase di crescita in adesione a quella di crescita in sospensione, risultava accompagnata dalla modulazione di numerosi geni, che è noto essere coinvolti nell’acquisizione di caratteristiche di malignità. Inoltre il profilo di espressione delle cellule a crescita in sospensione, siano esse originate per diluizione limite o per riduzione della concentrazione di siero nel mezzo di coltura, risultava essere del tutto simile. Lo studio in Real-Time, utilizzato per confermare quanto osservato mediante microarray, ha mostrato che quando le cellule di melanoma iniziavano a distaccarsi dal monostrato, in presenza di FBS all’1%, i geni BHLHB2 e MYC risultavano transitoriamente attivati. Nelle cellule in presenza di bassa concentrazione di siero e durante il passaggio verso la fase definitiva di crescita in sospensione, i geni PTEN, VEFGA, CSK, PITCH1, FOXG1A e TP53 risultavano progressivamente up-regolati. Nelle cellule di melanoma che avevano acquisito la capacità di crescere stabilmente in sospensione, si osservava infine aumento di espressione dei geni WNT3, MYCN, MYCL1, BTK, CCND2, WNT2, TIMP3, IRF3, GTF2I, CTNNB1, E2F1, ARHGAP5, ARHGEF5, GPR39 e ITGB4. Riduzione di espressione dei geni ANXA7, CTNNA1, NME1, RRM1, CDKN1A, XRCC6, HDAC, TRAM1, CD59 e TOB1 veniva riscontrata invece nelle cellule ancora adese, in presenza di 1 % di siero ed in quelle già in sospensione, rispetto alla linea di origine mantenuta in condizioni di coltura standard (10%FBS). In questo studio è stato per la prima volta descritto un sistema cellulare in cui è stata dimostrata la correlazione tra aumento di espressione di HERV-K e acquisizione di un fenotipo più aggressivo, nonché la modulazione dei geni che in tali processi risultano coinvolti. Tale modello può fornire pertanto un utile strumento per la comprensione dei meccanismi che regolano lo sviluppo e la progressione del melanoma, nonché per la valutazione di agenti farmacologici e modulatori di geni attivi nei confronti dell’espressione di HERV-K e nella progressione del melanoma.

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Freimanis, Graham L. "The detection and role of human endogenous retrovirus K (HML-2) in rheumatoid arthritis." Thesis, University of Wolverhampton, 2008. http://hdl.handle.net/2436/41777.

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Human endogenous retroviruses are the remnants of ancient retroviral infections present within our genome. These molecular fossils show similarities with present day exogenous retroviruses but act as typical Mendelian elements that are passed vertically between generations. Despite being repeatedly linked to a number of autoimmune diseases and disorders, no conclusive proof has been identified. Rheumatoid arthritis (RA) is one such disease which has been associated with an increase in HERV expression, compared to controls. In order to elucidate a clear role for HERVs in RA pathogenesis, autoantigens implicated in disease pathogenesis were scanned for sequence homology to retroviral genes. Such epitopes would induce antibodies cross reactive with host proteins, resulting in disease. Short peptides mimicking these regions were synthesised and the prevalence of anti-HERV antibodies was determined in RA patients and disease controls. Additionally, a novel real-time Polymerase Chain Reaction (PCR) assay was developed to accurately quantify levels of HERV-K (HML-2) gag expression, relative to normalised levels of housekeeping gene expression. Both serological and molecular assays showed significant increases in HERV-K (HML-2) activity in RA patients compared to disease controls with CD4+ lymphocytes harbouring the highest activity. The real-time assay was also used to determine whether factors within the synovium could modulate HERVs, resulting in their upregulation. Exogenous viral protein expression and pro-inflammatory cytokines were shown to exert a significant modulatory effect over HERV-K (HML-2) transcription. From this data, it is clear that RA patients have increased levels of HERV-K (HML-2) gag activity compared to controls. Despite this it is likely that factors within the synovium such as exogenous viral expression and pro-inflammatory cytokines also influence HERV-K (HML-2) transcription possibly contributing to a role of bystander activation, i.e. being influenced by external factors, rather than actively contributing to disease processes. The exact role of HERVs in RA pathology remains elusive; however this research proposes several mechanisms by which HERV-K (HML-2) may contribute to disease.

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MacFarlane, Catriona. "The genomic distribution of Human Endogenous Retroviruses (HERV-K) and the evolution of the primates." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/24866.

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Using my catalogue of HERV-K structure and integration site polymorphisms, PCR-based assays were developed for HERV-K loci and used to screen geographically diverse human DNA samples. The results indicate that the diversity of such elements is higher in African than non-African populations with 90.12 % to 99.37 % of genetic variation being within a population. Furthermore, the findings are consistent with African origin of contemporary humans which was followed by a complex process of interbreeding and population movement. Investigation of the biological contribution of HERV sequences in serving as nucleation points for chromosomal rearrangement demonstrated that such events have been extremely rare during primate genome evolution and may have been overestimated in previous studies. Analysis of HERV-K coding regions and subfamily phylogeny indicated that they have been subject to both purifying selection and extension sequence exchange throughout their expansion. Analysis of sequence variation at synonymous and non-synonymous sites in parsimony reconstructed sequences indicates that constraints on sequence variation have reduced over time, suggesting a decline in the likelihood of HERV functionality. Whilst the role of HERVs in primate evolution is yet to be fully understood, the comprehensive catalogue obtained in this study, the identification of novel proviral sequences and further elucidation of recombinant events provide the foundations for future functional and phylogenetic investigations of human and primate evolution and speciation.

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Ejtehadi, Hora Davari. "Study of human endogenous retroviruses HERV-K10 and ERV3 in cell lines and rheumatoid arthritis." Thesis, University of Wolverhampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414802.

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Holder, Elizabeth. "The role of placental human endogenous retroviruses and shed microvesicles on the maternal immune system." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/the-role-of-placental-human-endogenous-retroviruses-and-shed-microvesicles-on-the-maternal-immune-system(a4dfe0ac-c938-4768-99d6-7f132c5aecf9).html.

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Objectives: Human Endogenous Retroviruses (HERVs) were originally derived from germ cell infection by exogenous retroviruses and comprise around eight per cent of the human genome. HERVs are highly expressed in the placenta, where HERV-W (syncytin 1) has been demonstrated to perform a fusogenic function. Due to their retroviral origin, placental syncytin 1 has been suggested to also be involved in modulating the maternal immune system. The placenta constantly sheds microvesicles (MV) into the maternal circulation, demonstrated to cause innate immune cell activation associated with normal pregnancy. In pre-eclampsia, there is both increased placental MV shedding and a heightened pro-inflammatory immune response. It was therefore hypothesised that HERVs shed via placental MV play a role in feto-maternal immune interactions and thus may be an important factor in the pathogenesis of preeclampsia (PE). More specifically, it was hypothesised that syncytin 1-positive MV activate monocytes through toll-like receptor 4 (TLR-4). The aim of this study was to determine if syncytin 1 is released from the placenta via MV and exerts an immunological effect. Methods: HERV mRNA and protein expression was measured in placenta and the BeWo choriocarcinoma cell line by qPCR, western blotting (WB) and immunostaining. Glycosylation of syncytin 1 protein was determined by PNGase F treatment followed by WB. MV shed by first trimester, term normal and PE placental explants as well as BeWo cells were isolated by ultracentrifugation. Morphology of these microvesicles was examined by electron microscopy. Syncytin 1 protein and RNA was detected in microvesicles by WB and PCR. Activation and priming of PBMCs to respond to lipopolysaccharide (LPS) by syncytin 1-positive MV and recombinant syncytin 1 was examined through cytokine production by ELISA and multiplex. Antagonism of TLR-4 by LPS-RS was used to determine involvement of the receptor. The role of syncytin 1 in MV activation was examined by siRNA knockdown. Results: HERVs are highly expressed in placental tissue. Syncytin 1 is a glycosylated protein and its expression is altered in PE. MV shed from the BeWo choriocarcinoma cell line and from first trimester and term placental explants, express HERV protein and RNA. Syncytin 1 positive MV and recombinant syncytin protein cause activation of PBMCs. Greatest activation is stimulated by PE MV. Normal MV exhibit a neutral or suppressive effect on subsequent LPS challenge to PBMCs. PE MV exacerbate the response to LPS. Antagonism of TLR-4 on PBMCs and knockdown of syncytin 1 content in MV reduces activation by placental MV.Conclusions: The findings of this thesis suggest that syncytin 1 protein expressed by the placenta is shed into the maternal circulation via MV, and can activate immune cells through TLR-4. Syncytin 1-positive microvesicles may play a role in endotoxin tolerance of innate immune cells in pregnancy. The increased activation by PE MV implies that in addition to the increased microvesicle load in this pathology, a factor intrinsic to PE MV is responsible for increased inflammation. These studies implicate microvesicle-bound syncytin 1 in the regulation of immunotolerance during pregnancy.

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Morandi, Elena. "The viral hypothesis in multiple sclerosis : role of Epstein-Barr virus and human endogenous retroviruses." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/45125/.

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Epstein Barr Virus (EBV) is a major risk factor in Multiple Sclerosis (MS), via as yet unclear mechanisms. Several hypotheses have been proposed to explain how EBV infection could cause MS and the aim of this thesis was to better understand the mechanisms of action of EBV in the context of MS studying a) the role of EBV in myelin antigen presentation by B cells and b) the association of HERVs with MS. In a non-human primate experimental autoimmune encephalomyelitis (EAE) model, an EBV-related lymphocryptovirus enables B cells to protect a proteolysis-sensitive immunodominant myelin oligodendrocyte glycoprotein (MOG) peptide (residues 35- 55) against destructive processing. This facilitates its cross-presentation to autoaggressive cytotoxic MHC-E-restricted cytotoxic T cells. The present study extends these observations to human B cells and identifies a key role of autophagy. EBV infection upregulated antigen presentation-related markers on B cells and activated the cross-presentation machinery. Although human MOG protein was degraded less in EBV-immortalized B-lymphoblastoid cell lines (LCL) than in uninfected B cells, induction of cathepsin G activity by EBV led to total degradation of the immunodominant peptides. Inhibition of cathepsin G or citrullination of the arginine residue within a LC3-interacting regions (LIR) motif of immunodominant MOG peptides abrogated their degradation. Internalized MOG co-localized with autophagosomes, which may protect it from destructive processing. Thus, EBV infection switched MOG processing in B cells from destructive to productive possibly facilitating cross-presentation of disease-relevant epitopes to CD8+ T cells. This mechanism could facilitate presentation of myelin autoantigens that may be involved in MS induction and progression. The first part of this thesis shows a possible EBV-mediated mechanism involved in MS pathogenesis, but it is likely that different mechanisms act alternatively or cumulatively in different individuals based on environmental and genetic differences. A further mode of action of EBV is through the activation of Human Endogenous Retroviruses (HERVs). In normal conditions HERVs are silenced or expressed at low levels, but in some pathological cases, like MS, their expression is higher than in the healthy population. We performed a systematic review and meta-analysis of the literature on the association between HERVs and MS. The systematic review suggested a strong association between HERV expression and MS, in particular with the HERV-W family. The meta-analysis showed odds ratios of 22, 44, and 6 for the expression of MSRVpol in serum/plasma, MSRVenv in PBMC and MSRVpol in CSF respectively. Furthermore, we confirmed the association experimentally. An increased expression of MSRV/HERV-Wenv and TLR4 RNA was detected in blood of MS patients compared with control groups and the viral protein Env was expressed mainly by B cells and monocytes, but not by T cells. Our finding that EBV infection can induce the expression of MSRV/HERV-Wenv is consistent with previous reports in the literature. We also established that such increased expression was not due to a repression of retroviral restriction factors in LCL. A further connection between HERVs and MS is supported by the observation that people infected by HIV may have a lower risk of developing MS than the HIV non- infected, healthy population. We found that the expression of MSRV/HERV-Wenv RNA in HIV-infected people was lower than in MS patients and similar to healthy controls. Nevertheless, there was no difference in MSRV/HERV-Wenv expression between antiretroviral drug -treated and -untreated HIV patients. The expression of MSRV/HERV-Wenv was also detected in vitro in LCL treated with different classes of antiretroviral treatments (ART) and only Efavirenz (NNRI) reduced MSRV/HERV- Wenv expression. In conclusion, taking in consideration the multifactorial aetiology of MS, it is likely that EBV infection and increased expression of MSRV/HERV-W are significant contributing factors in genetically predisposed individuals. This thesis helps to better understand the mechanisms of action of EBV and HERVs in the context of MS.

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DENBOBA, AYELE ARGAW. "Human Endogenous Retrovirus-K affects cellular plasticity and generation of stem-like CD133+ cells in melanoma cancer cells." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2013. http://hdl.handle.net/2108/203227.

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Background: Malignant melanoma is one of the most aggressive types of skin cancers and its exact etiology is not yet clear. Tumor cell plasticity and the putative cancer stem cell subpopulations that express stem cell markers such as CD133 have been associated with melanoma tumor initiation and progression. Likewise, human endogenous retrovirus-K (HERV-K) has been linked to aggressiveness and immune evasion of metastatic melanoma. The exact mechanism leading to abnormal HERV-K gene expression in melanoma is not yet clearly elucidated. However, environmental factors such as stress conditions seem to be involved along with mechanisms interfering with the immune system. Protein mutations are no longer considered as sole drivers of melanoma tumors, which implies studying the role of HERV-K activation in melanoma development and progression is important to understand melanomagenesis and find a possible therapeutic target. Objective of the study: To investigate the potential role of HERV-K activation in cellular plasticity and stemness features of melanoma cells upon the modification of the microenvironment conditions. Materials and methods: Four metastatic and one primary melanoma cell lines were used in this study; cell lines TVM-A12 and TVM-A12-CD133+ were established in our laboratory. Different cell culture media were used to assess the cellular modification of cells upon the modification of the microenvironment. Flow cytometry, RT-PCR analysis, RNA interference assay, sphere-forming assay and migration/invasion assays were used to assess cell phenotypic modifications, expression of HERVK, stemness and metastatic features of the cell lines, respectively. SPSS software version 17 was used for the statistical analysis and statistical significance was set at P< 0.050. Results: The peculiar plasticity features of TVM-A12 cells were indicated by their ability to show specific differentiated and non-adherent grape-like cellular aggregate phenotypes in specific differentiation and serum-free stem cell media, respectively. The grape-like cellular aggregates were also accompanied by increased activation of HERV-K expression and generation of the stem-like CD133+ subpopulations melanoma cells. Interestingly, silencing of HERV-K expression in TVM-A12 cells by RNA interference significantly abolished the generation of the stem-like CD133+ subpopulations, dysregulated the grape-like cellular aggregates phenotype and suppressed their proliferation. Correspondingly, TVM-A12-CD133+ cell line was able to show cellular plasticity upon the modification of the microenvironments and displayed a significantly higher self-renewing, migration and invasion capacity than the heterogeneous TVM-A12 cell lines. More interestingly, treatment of TVM-A12 and TVM-A12-CD133+ with the NNRTIs, nevirapine and efavirenz, inhibited the expression of HERV-K and significantly induced high levels of apoptosis in TVM-A12-CD133+ cells. Conclusion: Therefore, taking these evidences together, this study demonstrated for the first time that the plasticity of melanoma cancer cells and their potential to generate the stem-like CD133+ cells under stress conditions are dependent upon HERV-K expression. Hence, given the relevance of the putative CD133+ cancer stem cells in melanoma progression we suggest HERV-K expression as a potential target of melanoma therapy in order to enhance the anti-metastatic effects and improve patient survival.

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PISANO, MARIA PAOLA. "Characterization of the Human Endogenous Retrovirus (HERV) HML-6 group and identification of HERV differential expression in immunity." Doctoral thesis, Università degli Studi di Cagliari, 2020. http://hdl.handle.net/11584/294812.

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Human Endogenous retroviruses (HERVs) are remnants of ancient retroviral infections that represent a large fraction of our genome. The HERV transcriptional activity is finely regulated in late developmental stages and the HERV expression is modulated in different cell types and tissues. The consequences of such activity may have an impact on both human physiology and pathology. Anyway, up to date, the HERVs contribution to our biology is only partially understood, often due to the poor characterization of the involved loci. For this reason, the comprehensive identification, classification and characterization of the HERV loci lay the foundations for studies of HERV expression and modulation. Moreover, novel high-throughput sequencing tools have recently allowed a great advancement in elucidating the various HERV expression patterns in different tissues, the control mechanisms of their transcription, and it overall helped in getting better insights in an all-inclusive understanding of the impact of HERVs in the biology of the host. In this work, we firstly focused on the analysis of the HML-6 group, a member of the class II Betaretrovirus-like. This group includes several proviral loci with an increased transcriptional activity in cancer. One HML-6 locus encodes the small protein ERVK3-1, expressed in various healthy tissues. Moreover, another HML-6 locus encodes HERV-K-MEL, a small Env peptide expressed in samples of cutaneous and ocular melanoma, but not in normal tissues. We characterized the group, reporting the distribution and genetic composition of 66 HML-6 elements. We analyzed the phylogeny of the HML-6 sequences and identified two main clusters. We provided the first description of a Rec domain within the env sequence of 23 HML-6 elements. A Rec domain was also predicted within the ERVK3-1 transcript sequence, revealing its expression in various healthy tissues. We reported the co-localization of 19 HML-6 elements with functional human genes. Indeed, we provided the first complete overview of the HML-6 elements in GRCh37(hg19), describing the structure, phylogeny and genomic context of insertion of each locus. Secondarily, we used a bioinformatic approach, based on RNA-sequencing (RNA-seq), to study the expression and modulation of HERVs in a scenario of immune system activation. We analyzed a dataset of Human Peripheral Blood Mononuclear Cells (PBMCs) RNA-seq from i) 15 healthy participants before and after the exposure to Lipopolysaccharide (LPS) ii) 19 subjects before and after the administration of an inactivated vaccine. We described the HERV transcriptome in PBMCs, finding that about 8 % of the HERV/MaLR loci were expressed, and identifying the Beta-retrovirus HERVs as those with the highest percentage of expressed loci. We found loci that were modulated as a result of both stimulation with LPS and vaccine administration. The HERV-H group showed the highest number of differentially expressed most intact proviruses. We characterized the HERV loci differentially expressed, checking their genomic context of insertion. In case of the LPS stimulation, that induces a strong activation of innate immune response, we observed a general co-localization with genes that are involved and modulated in the immunity. The analyses showed that HERVs and MaLRs are expressed in PBMCs and regulated in inflammatory settings. The modulation patterns of HERVs and MaLRs are different after LPS stimulation and vaccine administration, presumably indicating that such modulation patterns differ among innate and adaptive immune response.

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Silva, Danielle Ferreira e. "Avaliação da expressão de retrovírus endógenos humanos em pacientes com neuroblastoma." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-08092016-133959/.

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O neuroblastoma é o tumor sólido mais comum e com maior índice de letalidade em crianças. Diversas famílias de retrovírus endógenos humanos (HERV) estão presentes no genoma humano, em diferentes níveis de integridade, e são reativadas sob diferentes circunstâncias. A atividade de HERV tem sido cada vez mais sido associada a doenças como câncer, doenças autoimunes e ainda com a infecção por vírus exógenos. O principal objetivo deste projeto foi avaliar a expressão de retrovírus endógenos das famílias H (HH), W (HW) e K (HK) em pacientes diagnosticados com neuroblastoma. Amostras tumorais e amostras controle foram submetidas a extração de RNA total, síntese de cDNA e PCR em fase única. Os produtos de HERV foram submetidos ao sequenciamento em larga escala. No total, 43 loci de HH e 14 loci de HW foram diferencialmente expressos entre os grupos e 202 loci de HK foram detectados. As análises de expressão somadas ao contexto genético e epigenético de neuroblastoma, permitiram com que várias hipóteses fossem levantadas acerca da regulação da expressão de HERV neste tumor. A hipometilação geral do tecido tumoral pode ter um papel importante na expressão gênica e na reativação de retrotransposons, podendo ser a principal razão para a expressão de HERV neste contexto.
Neuroblastoma represents the most common solid tumor as well as the most lethal form of tumor in children. Several families of human endogenous retroviruses (HERV) are present in human genome in different integrity levels, and they are reactivated under different circumstances. HERV activity has been linked to diseases such as cancer, autoimmune diseases and even with the infection by exogenous viruses. The main goal of this project was to evaluate the expression of endogenous retroviruses families H (HH), W (HW) and K (HK) in patients diagnosed with neuroblastoma. Tumor samples and control samples were subjected to RNA extraction and a single round in-house RT-PCR. HERVs amplicons were next generation sequenced to access the specific origin of transcripts. Overall, 43 HH loci and 14 HW loci were differentially expressed between groups and, 202 HK loci was detected. Taken together, HERV expression analysis and genetic and epigenetic context of neuroblastoma provided several hypotheses about regulation of HERV expression in this type of tumor. The global hypomethylation of tumoral tissue may have a role in genes expression and retrotransposons reactivation, which may be the main reason for HERV expression in this context.

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Fimereli, Danai. "Computational analyses of gene fusions, viruses and parasitic genomic elements in breast cancer." Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/263609.

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Breast cancer is the most common cancer in women and research efforts to unravel the underlying mechanisms that drive carcinogenesis are continuous. The emergence of high-throughput sequencing techniques and their constant advancement, in combination with large scale studies of genomic and transcriptomic data, allowed the identification of important genetic changes that take place in the breast cancer genome, including somatic mutations, copy number aberrations and genomic rearrangements.The overall aim of this thesis is to explore the presence of genetic changes that take place in the breast cancer transcriptome and their possible contribution to carcinogenesis. The aim of the first research study was the identification of expressed gene fusions in breast cancer and the study of their association with other genomic events. For achieving this, transcriptome sequencing and Single Nucleotide Polymorphism arrays data for a cohort of 55 tumors and 10 normal breast tissues were combined. Gene fusions were detected in the majority of the samples, with evident differences between breast cancer subtypes, where HER2+ samples had significantly more fusions than the other subtypes. The genome-wide analysis uncovered localization of fusion genes in specific chromosomes like 17, 8 or 20. Additionally, a positive correlation between the number of gene fusions and the number of amplifications was observed, including the association between fusions on chromosome 17 and the amplifications in HER2+ samples, which can be attributed to the highly rearranged genomes of these subtypes. Finally, the absence of highly recurrent fusions across this cohort adds to the notion that gene fusions in breast cancer are most likely private events, with the majority being “passenger” events. In the second research study, the aim was to identify a connection between viral infections and breast cancer by devising five different computational methods for the analysis of both transcriptome and exome data in a cohort of 58 breast tumors. Despite being able to detect viral sequences in our testing dataset, no significantly high numbers of viral sequences were detected in our samples. Specifically, viral sequences (~2-30 reads) were extracted belonging to viruses EBV, HHV6 and Merkel cell polyomavirus. Such low levels of viral expression direct against a viral etiology for breast cancer but one should not exclude possible cases of integrated but silent viruses.In the third research project, we analyzed in silico the transcriptional profiles of human endogenous retroviruses in breast cancer. Despite being scattered across the genome in large numbers, a number of ERVs are actively transcribed, consisting of a small percentage of the total mapped reads. Alongside protein coding genes and lncRNAs, they show distinct expression profiles across the different breast cancer subtypes with luminal and basal-like samples clear separating from each other. Additionally, distinct profiles between ER+ and ER- samples were observed. Tumor specific ERV loci show an association with the immune status of the tumors, indicating that ERVs are reactivated in tumors and could play a role in the activation of the immune response cascade.The results presented in this thesis exhibit only in a small fragment the diversity and heterogeneity of the breast cancer transcriptome. The strength of the sequencing techniques allows the in depth detection of different genomic events. Gene fusions should be considered as part of the breast cancer transcriptome but their low recurrence across samples indicates for a role as passenger events. Under the light of existing results, viral infections do not play a significant role in breast cancer. On the other hand, human endogenous retroviruses, despite originating from exogenous viruses, seems to exhibit transcriptional profiles similar to those of normal genes, indicating that they are part of the genome’s transcriptional machinery.
Doctorat en Sciences biomédicales et pharmaceutiques (Médecine)
info:eu-repo/semantics/nonPublished

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CADEDDU, MARTA. "Characterization of the human endogenous retrovirus HERV-‐K(HML-‐6) and HERV-‐K(HML-‐10) sequences and analysis of their expression." Doctoral thesis, Università degli Studi di Cagliari, 2016. http://hdl.handle.net/11584/266897.

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It has been estimated that 8% of human genome is composed of sequences originating from exogenous retroviruses that infected the germ line cells over millions of years and are termed human endogenous retroviruses (HERVs). After germ line infection, the retroviral DNA was integrated into the genome and transmitted through vertical transmission in the progeny by Mendelian laws. ERVs have been found in all vertebrates, indicating that the process of endogenization was quiet common, and have been considered retroviral fossil whose phylogenetic analysis provides important information on evolution. During the million of years after their integration, ERV sequences have accumulated abundant mutations (deletions, insertions, duplications, and rearrangements) that have caused loss of virulence, contributing to the current composition of the actual HERV. Several studies suggested the ability of HERVs to significantly interfere in human biology, in both physiological and pathological scenarios. However, despite a few cases such as the one of Syncityn--‐1, the HERV physiological role an their involvement in the development of diseases such as cancer, autoimmune diseases, neuronal diseases and other disorders is still controversial. Among the most studied HERVs is the betaretrovirus HERV--‐K(HML1--‐10) clade, composed of 10 groups whose correlation with diseases has been proposed in a number of cases. In particular, it has been reported that the env gene, termed HERV--‐K--‐MEL, is expressed in melanoma cells and not in healthy controls. In addition, it has been demonstrated that the low copy number of HML--‐10 sequences within the complement C4 gene of the major histocompatibility complex is related to a higher frequency of Type 1 Diabetes, hypothesizing that these elements could act as antisense control or be controlled by other HML--‐10 sequences that could be involved in Type 1 Diabetes. Given the many accumulated mutations and their high copy number, HERV studies have been hampered by the lack of precise information on their chromosomal localization and composition. Recently, the use of a novel bionfomatic approach allowed us to precise identify a total of 3173 sequences in 5 the human genome assembly GRCh37/hg19. Hence in the present work we wanted to fully characterize two HERV--‐K subgroups, the HML--‐10 subgroup that includes 9 proviruses with 5 haplotypes, and the HML--‐6 subgroup that includes 63 proviruses. The HML--‐10 and HML--‐6 analysis allowed to i) confirming their classification by an innovative methodology of Similarity image (Simage) analysis, ii) precisely defining the retroviral structure in each locus, iii) determining the presence of the betaretrovirus feature in all the identified sequences; iv) assessing the putative time of integration of each retroviral sequence and v) verifying the presence of some of the sequences also in no--‐ human primates. In addition, we assessed the expression of HML--‐10 and HML--‐6 sequences by analyzing three public RNAseq databases comprising > 30 different tissues isolated from healthy individuals as well as mRNA from patients with autoimmune diseases such as Type 1 Diabetes, Systemic Lupus Erythematosus and Multiple Sclerosis. Data showed that some HML--‐6 sequences are expressed in a number of healthy tissues while no HML--‐10 expression has been specifically observed in these dataset. Overall, these results increase the knowledge of the composition of the human genome and lay the foundation for a better understanding of the potential physiological and pathological role of HML--‐6 and HML--‐10 retroviruses.

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Al-shehabi, Hussein [Verfasser]. "The role of human SAMHD1 in restricting porcine endogenous retroviruses (PERVs) and the innate immune response to PERV infection in human primary immune cells / Hussein Ali Nasser Al-shehabi." Berlin : Freie Universität Berlin, 2020. http://d-nb.info/1215099088/34.

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Al-shehabi, Hussein Ali Nasser [Verfasser]. "The role of human SAMHD1 in restricting porcine endogenous retroviruses (PERVs) and the innate immune response to PERV infection in human primary immune cells / Hussein Ali Nasser Al-shehabi." Berlin : Freie Universität Berlin, 2020. http://d-nb.info/1215099088/34.

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MORONI, GABRIELLA. "Human melanoma phenotypes and HERV-K expression." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/696.

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Lo sviluppo del melanoma è un processo multistep che insorge da un a serie di eventi genetici ed epigenetici che includono la trasformazione cellulare e un cambiamento nelle interazioni tra le cellule trasformate e l’ospite. Mentre è ben definita la sequenza degli stadi coinvolti nella progressione da melanocita a melanoma maligno, poco si conosce invece circa gli eventi che portano all’insorgenza e alla progressione del melanoma. Sempre maggiori evidenze mostrano che l’attivazione di sequenze retrovirali endogene possono essere coinvolte nella trasformazione dei melanociti così come nell’aumentata capacità delle cellule di melanoma di sottrarsi ai meccanismi di immunosorveglianza dell’ospite. In questo studio dimostriamo che cellule di melanoma in vitro spontaneamente danno origine ad un fenotipo non- aderente più maligno, caratterizzato da un incremento del potenziale proliferativo e da una riduzione dell’espressione sia delle molecole di HLA di classe I sia dell’antigene Melan-A/MART -1, elementi che caratterizzano le cellule ad alta malignità. Questo fenotipo e le modificazioni funzionali sono accompagnate dall’attivazione dell’espressione del retrovirus-K endogeno umano (HERV-K) e dalla massiva produzione di particelle simil-virali, suggerendo una stretta correlazione tra la replicazione dell’ HERV e la progressione del melanoma.
Melanoma development is a multistep process arising from a series of genetic and epigenetic events that includes cell transformation and the change in the interactions between the transformed cells and the host. Despite the clearly defined sequential stages involved in the progression from melanocytes to malignant melanoma, little is known about the events leading to melanoma insurgence and progression. Growing evidence show that the activation of endogenous retroviral sequences might be involved in transformation of melanocytes as well as in the increased ability of melanoma cells to escape immune surveillance. In this study we show that melanoma cells in vitro spontaneusly gave rise to a more malignant non-adherent phenotype, characterized by an increased proliferative potential and a decreased expression of both HLA class I molecules and Melan-A/MART-1 antigen, features that typically characterize highly malignant cells. These phenotypic and functional modifications are accompanied by the activation of human endogenous retrovirus-K (HERV-K) expression and a massive production of viral-like particles, suggesting a tight correlation between HERV replication and melanoma progression.

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GRANDI, NICOLE. "Identification and characterization of Type W Human Endogenous Retroviruses (HERV-W) in humans and comparative analysis of the group in non-human primates: new insights on HERV-W diffusion in Simiiformes and analysis of evolutionarily highly related sequences in New World Monkeys." Doctoral thesis, Università degli Studi di Cagliari, 2017. http://hdl.handle.net/11584/249598.

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Human Endogenous Retroviruses (HERVs) are ancient infections relics constituting~8% of our DNA. While HERVs genomic characterization is still ongoing, impressive amounts of data have been obtained on some HERV groups general expression across human tissues, primarily to find a role in pathogenesis. Among HERV groups, one of the most explored is the HERV-W one, initially studied for an element integrated in locus 7q21.2 and encoding a functional envelope protein coopted for placentation. The group has been also highly investigated for its role in several diseases, such as cancer, inflammation and autoimmunity. However, no conclusive correlations have been demonstrated so far. In general, both i) the absence of an exhaustive characterization of the HERV-W group at the genomic level and ii) the lack of a proper identification of which specific HERV-W locus is expressed in a given condition, currently prevents the assessment of the single HERV-W loci expression in the different physio-pathological contexts and their effective exploitation either as innovative diagnostic or therapeutic targets. The present work was aimed to provide a comprehensive characterization of the HERV-W group in the human genome, setting the bases for a more rationale analysis of its specific contribution to our transcriptome to understand the potential effects exerted by HERV-W loci and expressed products. 213 HERV-W sequences were retrieved from human genome assembly GRCh37/hg19 and analyzed in terms of structure, context of insertion, phylogeny and time of integration; providing, to our knowledge, the most complete and exhaustive HERV-W dataset up to date. Moreover, to better understand the dynamics of diffusion of (H)ERV-W elements, we comparatively analyzed the group presence in the genome of 12 non-human primates, belonging to Siimiformes (Catarrhines and Platyrrhines), Tarsiiformes and Prosimians. The data obtained provide a complete analysis of the ERV-W group presence in the primate lineages, including ERV-W loci orthologous to human integrations, ERV-W species-specific insertions and LTR-LTR recombination events along primates speciation, further detailing the group diffusion in primates. Interestingly, in Platyrrhini species we identified an ERV group named ERV1-1 showing high identity to the ERV-W elements. The analysis of the 130 most complete ERV1-1 sequences retrieved from Marmoset (C. jacchus) and Squirrel Monkey (S. boliviensis) allowed us to confirm the phylogenetic relation of the ERV1-1 group to the ERV-W one, possibly suggesting the presence of a common ancestor. To gain more insights into the ERV1-1 group and its unreported relation with ERV-W, the ERV1-1 sequences structure, context of insertion, phylogeny and time of integration have been characterized. Such analysis provided, for the first time, a detailed description of the group, pointing out the various structural features shared with ERV-W elements, among which an unusual “pre gag“ region. Considering that the pre gag is a stable component of the ERV-W structure, for which neither origin nor function has been hypothesized yet, we analyzed in detail this region comparing it with the ERV1-1 pre gag. Results showed that ERV-W and ERV1-1 pre gag share nucleotide identity in the 5’-portion, while~40% of the ERV-W pre gag sequence was highly similar to a portion of the HERVIP10F ORF2, encoding for a pol protein Ribonuclease H domain. The same HERVIP10F-like pre gag region had been provided by the ERV-W sequences to Harlequin mosaic elements, possibly suggesting recombination events involving this portion. Interestingly, in both ERV-W and ERV1-1 consensus sequences, RetroTector software detected the presence of a putative exon spanning the pre gag region. Considering that the predicted encoded peptides showed no homology with any known proteins, further studies are needed to assess the native role of the pre gag elements maintained in these and the other related Gammaretroviruses

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Baker, Bradley J. "The evolutionarily related major histocompatibility complex and CD1 : evolution of an endogenous retrovirus responsible for a polymorphism in human C4 and the biochemical characterizations of CD1A and E /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu148794983620512.

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Montgiraud, Cécile. "Définition de puces à ADN dédiées aux rétrovirus endogènes humains : applications à l’analyse du contrôle épigénétique et transcriptionnel." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10195.

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Les rétrovirus endogènes (ERV) sont constitutifs du génome des eucaryotes et représentent environ 400000 loci dans le génome humain divisés en différentes familles. Ces HERV (Human ERV) sont pour la majorité silencieux en contexte physiologique excepté dans le placenta mais présentent une activité transcriptionnelle en contexte pathologique comme par exemple dans les cancers. Il est difficile de comprendre de façon systématique les mécanismes de régulation/dérégulation des HERV et leur implication en contexte physiopathologique car il n’existe à ce jour aucun critère permettant de distinguer qu’elles sont les longues terminaisons répétées (LTR) transcriptionnellement actives dans l’ensemble de ces éléments de régulation. Nous avons développé deux générations de puces à ADN haute densité afin d’appréhender quelles étaient les LTR réactivées dans les cancers et de comprendre les mécanismes sous-jacents à la transcription des HERV. Avec la première version de la puce HERV, nous avons notamment identifié six loci de la famille HERV-W différentiellement exprimés dans le cancer testiculaire dont le locus ERVWE1 qui code pour la syncytine-1 impliquée dans la morphogénèse placentaire. L’analyse de l’ADN des tumeurs et des tissus sains adjacents démontre que l’hypométhylation des régions U3 promotrices est un pré-requis à l’activation des HERV. La deuxième version de la puce HERV a été utilisée pour une recherche de biomarqueurs pronostiques dans le cancer du poumon non à petites cellules. Ceci a permis de mettre en évidence des réactivations de HERV dans certains échantillons cancéreux et illustre la difficulté d’une telle approche au regard des disparités inter-individus
Endogenous Retroviruses (ERVs) are inherited part of the Eukaryotic genomes, and represent about 400,000 loci in the Human genome divided in distinct families. The majority of HERVs (Human ERV) are mainly silent in most physiological contexts excepted in placenta, whereas a significant expression is observed in pathological contexts such as cancers. It is difficult to understand HERV (de)regulation mechanisms and their implication in physio-pathological contexts, as there is no criteria defining transcriptional active promoters HERV long terminal repeats (LTRs) among all these regulatory élements. We developed two versions of highdensity DNA microarray to specifically detect LTR reactivated in cancers and try to understand transcription mechanism of HERV. With the first version of HERV-microarray, we identified six HERV-W loci over-expressed in testicular cancer, including the domesticated ERVWE1 locus which produces an envelope protein dubbed Syncytin-1 associated with placenta development. The analysis of DNA from tumoral versus normal tissue reveals that hypomethylation of U3 promoters in tumors is a prerequisite of HERV activation. The second version of HERV-microarray was used to identify prognosis biomarkers in non small cell lung cancer. This study identified HERV reactivation in some samples and highlighted difficulties of such approach due to inter-individuals disparities

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Gimenez, Juliette. "Implication de la méthylation dans le contrôle de l'expression de rétrovirus endogènes humains en contextes physiologiques et pathologiques." Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10222.

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Les rétrovirus endogènes (ERV) sont des éléments constitutifs de la plupart des génomes eucaryotes, et représentent chez l’humain environ 400000 loci. Les HERV sont divisés en familles distinctes, composées d’éléments apparentés mais structurellement hétérogènes. Leur activité peut être néfaste, neutre, mais aussi bénéfique. La majorité des HERV semble silencieuse dans les cellules somatiques. Cependant certains présentent une forte activité en contextes physiologiques. Par ailleurs, une expression significative de HERV est fréquemment observée dans des contextes pathologiques, tels que les cancers. La mise sous silence des éléments répétés est supposée se produire principalement par la méthylation de leur ADN. Nous nous sommes donc intéressés à l’implication de la méthylation des régions régulatrices des HERV, les LTR, dans le contrôle de leur expression. D’une part cette étude nous a permis de mettre en évidence une méthylation locus- et tissu- spécifique de LTR HERV en contexte physiologique, impliquant notamment des modalités particulières de méthylation contrôlant l’expression placentaire de HERV domestiqués. D’autre part ce travail nous a permis de déterminer que six loci HERV-W, incluant un locus domestiqué, sont réactivés de manière autonome dans des tumeurs testiculaires sous l’influence d’un changement de modalité de méthylation intra-famille. Ainsi la méthylation des HERV influence leur expression, mais sous des modalités variables selon les loci et les contextes concernés
Endogenous retroviruses are constitutive elements of most eukaryotic genomes. They represent about 400,000 loci in the human genome. HERVs are divided into distinct families on the basis of phylogenetic identities but are highly heterogeneous in structures. Their activity can be detrimental, neutral, or beneficial to the host. Majority of HERVs seems silent in somatic cells. Still, some are highly expressed in physiological contexts. Besides, a significant expression of HERVs is frequently observed in pathological contexts such as cancers. Silencing of repeated elements is supposed to occur mainly through DNA methylation. We were therefore interested by the implication of HERV regulatory region (LTR) methylation in the control of their expression. First, this study identified locus and tissues –specific HERV LTR methylation in physiological context, worth noting particular methylation modalities that control domesticated HERVs placental expression. Second, we could determine a change in intra-family LTR methylation modalities in testicular tumors leading to the autonomous reactivation of six HERV-W loci, among which a domesticated one. Thus methylation clearly influences HERVs expression, but under modalities varying upon the loci and the contexts

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Schönfeld, Regine Margarete. "Generation of Transgenic Mice to Evaluate Promoter Activity and Specificity of Two Human Endogenous Retrovirus Long Terminal Repeats = Untersuchungen zur Promotor-Aktivität und -Spezifität von zwei Long Terminal Repeats humaner endogener Retroviren in transgenen Mäusen." Diss., lmu, 2003. http://nbn-resolving.de/urn:nbn:de:bvb:19-9017.

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BEYER, ULRIKE [Verfasser], Matthias [Akademischer Betreuer] Dobbelstein, Ralf [Akademischer Betreuer] Ficner, and Thomas [Akademischer Betreuer] Pieler. "Novel proapoptotic p63 isoforms are driven by an endogenous retrovirus in the male germ line of humans and great apes, likely increasing genome stability / Ulrike Beyer. Gutachter: Ralf Ficner ; Thomas Pieler ; Matthias Dobbelstein. Betreuer: Matthias Dobbelstein." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2011. http://d-nb.info/1043068910/34.

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Perot, Philippe. "Étude du transcriptome des rétrovirus endogènes humains et implications fonctionnelles : applications à la recherche de marqueurs diagnostiques de cancers." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10228/document.

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Le génome humain contient environ 200 000 séquences d'origine rétrovirale (HERV), intégrées au fil de l'évolution et organisées aujourd'hui en familles multicopies complexes globalement réprimées par un contrôle épigénétique. L'étude du transcriptome HERV au niveau locus est compliquée par les similarités phylogénétiques au sein d'une famille et par la profusion des sites d'intégration, deux propriétés inhérentes aux éléments transposables. Dans ce travail, nous avons utilisé une méthode de conception de sondes de détection de 25 mer afin d'adresser la question de l'expression individuelle des HERV. Une puce à ADN haute densité intégrant plus de 5 500 séquences HERV et permettant une lecture fonctionnelle de l'activité de leurs LTRs a été utilisée sur un panel de tissus sains et cancéreux. Cela a permis d'identifier 1 718 séquences HERV actives, dont 326 LTRs promotrices et 209 LTRs polyA. L’étude de l’environnement génomique a mis en évidence une fenêtre d’environ 8 kb en amont des LTRs promotrices, caractérisée par une sous-représentation en gènes cellulaires en orientation sens. Nous avons également montré que le transcriptome des rétrovirus endogènes humains suit des règles de tropisme d’expression, qu’il est sensible aux états de différenciation cellulaire et qu’il ne semble pas être corrélé à l’âge des familles. Une première tentative d’exploitation de ce répertoire HERV dans un contexte clinique a visé à rechercher de nouveaux marqueurs diagnostiques du cancer de la prostate à partir de prélèvements urinaires, par la réalisation d’une étude pilote sur 45 patients
The human genome contains around 200,000 endogenous retroviral sequences (HERV) integrated during the evolution and which are nowadays organized into complex multicopy families, globally repressed by epigenetic control. The study of the HERV transcriptome at the locus level is complicated by phylogenetic similarities within one family and by the profusion of integration sites, two inherent characteristics of transposable elements. In this work, we used a method aiming to optimally characterize individual loci associated with 25 mer probes. A custom microarray dedicated to more than 5,500 HERV sequences and allowing a functional interpretation of the LTRs expression was used on a panel of normal and tumor tissues. We therefore identified 1,718 active HERV sequences, including 326 promoter LTRs and 209 polyA LTRs. The study of the genomic environment has highlighted an approximately 8 kb zone upstream of promoter LTRs characterized by a drastic reduction in sense cellular genes. We also showed that the HERV transcriptome follows tropism rules, is sensitive to the state of cell differentiation and, unexpectedly, seems not to correlate with the age of the families. In a first attempt to use the HERV repertoire in clinical, we sought to identify new markers of prostate cancer from urine samples. This goal was pursued by conducting a pilot study on 45 patients

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Mommert, Marine. "Modulation de l'expression des rétrovirus endogènes humains dans des contextes d'inflammation et d'immunosuppression." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN044.

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Le sepsis est défini par l’apparition de dysfonctions d’organes, multiples et mortelles, causées par une réponse de l’hôte dérégulée suite à une infection. L’hétérogénéité de la maladie représente un défi clinique majeur au regard de la prise en charge thérapeutique, et à ce jour les marqueurs proposés ne suffisent pas à stratifier les patients. Les rétrovirus endogènes humains (HERV) pourraient être des marqueurs pertinents,compte tenu des propriétés immunosuppressives de leurs enveloppes et de leur expression dans des maladies inflammatoires et auto-immunes. Cette thèse a pour objectif de savoir dans quelle mesure les HERV sont exprimés et modulés, dans des conditions d’inflammation et d’immunosuppression. Pour cela,nous avons utilisé une puce à ADN haute densité permettant (i) l’analyse de la transcription de 363 689HERV et 1500 gènes, et (ii) une lecture fonctionnelle de l’activité des LTR. L’expression des HERV a été objectivée (i) dans un modèle ex-vivo de tolérance à l’endotoxine sur des cellules mononuclées du sang périphérique (PBMC) d’individus sains et (ii) sur sang total provenant d’individus sains et de patients en choc septique, stratifiés ou non en fonction du statut immunitaire. (1) De 5,6% à 6,9% des HERV sont exprimés dans le compartiment sanguin et environ 20% des LTR possèdent une fonction promotrice ou polyA, les deux fonctions étant mutuellement exclusives. (2) Le contenu du transcriptome HERV est modulé ex vivo dans le contexte de tolérance à l’endotoxine laissant apparaitre deux grands phénotypes transcriptionnels. L’expression de certains loci HERV est corrélée au statut immunitaire de patient septique.L’évaluation d’une signature moléculaire complexe sur une cohorte de validation, permet la séparation en deux groupes présentant des critères de sévérité distincts, suggérant les HERV/MaLR comme biomarqueurs de stratification. (3) L’analyse de la co-expression des gènes et des HERV a permis d’intégrer ceux-ci au sein de réseaux associées à la réponse de l’hôte et de proposer des hypothèses fonctionnelles
Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection.The heterogeneity of the disease present a major clinical challenge with regard to the therapeutic coverage,and this day the proposed markers are not enough to stratify patients. The human endogenous retrovirus(HERV) could be relevant markers, considering the immunosuppressives properties of their envelopes andtheir expression in inflammatory and autoimmune disease. The aim of this thesis is to know to what extentthe HERVs are expressed and modulated, in inflammatory and immunocompromised contexts. For this, weused a high density DNA chip allowing (i) the transcription analysis of 363,689 HERV and 1500 genes,and (ii) a functional reading of LTRs activities. The HERVs expression was objectified (i) in endotoxintolerance ex vivo model in peripheral blood mononuclear cells (PBMCs) of healthy volunteers and (ii) inwhole blood of healthy volunteers and septic shock patients, stratified or not according to immunity state.(1) Of 5,6% at 6,9% of HERVs are expressed in the blood compartment and around 20% of LTRs have apromoter or polyA function, both functions being mutually exclusive. (2) The HERV transcriptome ismodulated in ex vivo endotoxin tolerance model letting appear two higher transcriptional phenotypes. Theexpression of some HERVs loci are correlated of the immunity state of the septic shock patients. Theevaluation of molecular signature in validation cohort, allowed to separate in two patients groupspresenting different severity criteria, suggesting HERV/MaLR as biomarkers of stratification. (3) The coexpressedanalysis of genes and HERVs allowed to integrate these within signaling pathways associated atthe host immune response and to provide functional hypothesis

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Tabone, Olivier. "Rétrovirus endogènes humains et réponse immunitaire de l’hôte suite à une agression inflammatoire." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1015.

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Suite à une agression inflammatoire, telle que le choc septique, des brulures graves ou un traumatisme sévère, le système immunitaire répond par une modulation massive du transcriptome dans le sang. On propose d’explorer un autre répertoire que l’expression des gènes et de s’intéresser aux éléments répétés du génome, peu étudiés dans ces contextes, et plus particulièrement aux rétrovirus endogènes humains (HERV). Ils représentent plus de 8% du génome chez l’Homme. Certains sont exprimés dans des situations similaires à l’agression inflammatoire (cancer, maladies auto-immunes) et ont un impact sur la réponse immunitaire.Dans ce travail, nous cherchons à décrire et comprendre la contribution des HERV, au sein de la réponse immunitaire de l’hôte à l’agression inflammatoire. Pour cela, nous avons développé des méthodes et outils spécifiquement dédiés à la description du HERVome, au niveau génomique et transcriptomique. Nous montrons que les HERV sont exprimés dans le sang, modulés chez les patients, et que certains pourraient jouer un rôle sur l’expression de gènes de la réponse immunitaire situés à proximité. Nous évaluons également le polymorphisme de présence des HERV dans le génome de plus de deux mille individus répartis dans les populations humaines. On met en évidence que le polymorphisme HERV est globalement important, qu’il est lié à la population d’appartenance et que certains loci sont absents dans la majorité des génomes étudiés. Finalement, par différentes approches, nous identifions des associations entre gènes de la réponse immunitaire et HERV, suggérant que ces éléments peuvent jouer un rôle important dans la réponse de l’hôte à l’agression inflammatoire
Following inflammatory injury, like a septic shock, severe burn or important trauma, the immune system responds by a massive modulation of its transcriptome in the blood. We propose to explore another repertoire than gene expression and to focus on repeated elements, especially on HERVs. They represent more than 8% of the human genome. HERVs are expressed in similar settings (cancer or auto-immune diseases) and impact immune response. In this project, we describe and aim to better understand the HERV contribution in host immune response, following inflammatory aggression. To bring elements of response, we developed specifically dedicated tools to describe the HERVome, either at genomic or transcriptomic level. We show HERVs are expressed in blood in these settings, modulated in patients and could play a role on nearby gene expression. We also evaluate the polymorphism of presence of HERV loci on more than two thousands individuals, grouped into human populations. We show an important HERV polymorphism, that it is population-specific, and that some loci are absent in the majority of the analyzed genomes.Finally, with different approaches, we identify associations between immune-response genes and HERVs, suggesting these elements can play a role in host immune response following inflammatory aggressions

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Reynaud, Joséphine. "Développement d'un modèle murin transgénique d'infection par l'herpèsvirus 6A et étude des mécanismes d'induction de la neuroinflammation." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2013. http://tel.archives-ouvertes.fr/tel-00998378.

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L'herpèsvirus humain (HHV) 6 est un betaherpèsvirus largement répandu, associé à plusieurs maladies neuroinflammatoires, telles que des encéphalites ou la sclérose en plaques (SEP). Cependant, les mécanismes impliqués dans la neuropathologie induite par les deux espèces d'HHV-6, HHV-6A et HHV-B, sont peu connus. De plus, l'absence de modèle d'infection chez le petit animal a ralenti l'étude de la pathogénèse virale. Dans ce contexte, nous avons développé un modèle d'infection par HHV-6 chez des souris transgéniques, qui expriment la protéine CD46 humaine, identifiée comme récepteur cellulaire pour HHV-6. Nous avons pu démontrer une persistance de l'ADN viral d'HHV-6A, mais pas d'HHV-6B, dans le cerveau de souris transgéniques pendant plusieurs mois. De plus nos résultats montrent qu'HHV-6A induit la sécrétion de chimiokines pro-inflammatoires par les cellules neurales murines et provoque l'infiltration de cellules immunitaires dans le cerveau de souris infectées. Enfin, HHV-6A, mais pas HHV-6B, pourrait induire des réponses cellulaires chez les cellules murines via le récepteur de l'immunité innée TLR9 (toll-like receptor 9). En collaboration avec une équipe de Grenoble, nous avons ensuite montré que l'infection par HHV-6A induit l'expression de rétrovirus endogènes humains (HERV) dans des cellules mononuclées et des lignées neurales humaines. Ces HERV, en particulier leurs protéines d'enveloppe qui présentent des propriétés pro-inflammatoires, sont associés à diverses maladies autoimmunes dont la SEP. HHV-6A pourrait donc participer au développement de pathologies inflammatoires via l'induction de ces HERV. L'ensemble de ces travaux supporte ainsi l'existence d'un lien entre l'infection par HHV-6A et la neuroinflammation, et apporte de nouvelles pistes quant aux mécanismes potentiellement impliqués.

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Simmons, William Minnow. "Contributions of viral and cellular gene products to the pathogenesis and prognosis of aggressive lymphomas." Thesis, University of Wolverhampton, 2016. http://hdl.handle.net/2436/609034.

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High grade aggressive lymphomas have high mortality. By their nature, more than 40% of patients die from these diseases even with the improved treatment strategies currently available for oncology patients. The characteristic feature is that they are functionally heterogeneous and therefore have different biological and molecular signatures which make it difficult for all groups to respond to same line of treatment. Based on the above, I set out to look at the impact of viral and cellular gene products on these groups of diseases: In chapter 3 I developed monoclonal antibodies against HERV‐K10. I subsequently investigated their expressions in aggressive lymphomas including Diffuse Large B‐cell lymphoma, Hodgkin’s lymphoma and Primary CNS lymphomas. I showed HERV‐K10 is expressed in cell lines of aggressive lymphomas, but not in paraffin‐embedded tissues. In chapter 4 I showed that the expression of ATM using immune‐histochemistry techniques in aggressive lymphomas does offer a guide to prognosis and treatment. Nearly 30% of Diffuse Large B‐cell lymphomas express ATM, 55% of Hodgkin’s lymphomas and more than 80% of Primary CNS lymphomas. I also showed there is a correlation of ATM expression and EBV‐driven aggressive lymphomas and that this has a poor prognostic significance. Chapter 5 analysed the results obtained by generating, validating and evaluating data base of DLBCL and PCNSL from a retrospective cohort over a 17‐year period. The results confirmed that prognostic indicators including ATM, S1PR2, Autotaxin and EBV using immuno‐histochemistry techniques help with categorising aggressive lymphomas into different prognostic groups and does influence future management. In summary, my results showed there is a critical place for immuno‐histochemistry techniques in convincingly helping understand the expressions of viral and cellular gene products in aggressive lymphomas and in contributing positively to their management.

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Grosjean, Iris. "SQSTM1, une protéine de plateforme à la croisée de la réponse aux dommages à l’ADN et de la réponse à l’immunothérapie dans le cancer : rôles des rétrovirus endogènes." Electronic Thesis or Diss., Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ6037.

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Le cancer du poumon non à petites cellules (CPNPC) est le cancer le plus mortel au monde, en partie en raison de résistance acquises chez des patients qui initialement répondaient aux thérapies anti-cancéreuses comme les chimiothérapies génotoxiques et la radiothérapie (agents endommageant l'ADN, nommés ci-après DDA) et aux thérapies ciblées. L’immunothérapie (dont les inhibiteurs des points de contrôle immunitaires (ICI)) est une véritable révolution dans la prise en charge des patients. Cette stratégie a en effet eu un impact positif rendant des cancers avancés n’ayant pas de cibles « actionnables » que l’on considérait incurables, traitables. La survie à 5 ans est passée de seulement 5% avec un traitement conventionnel à 20% avec les immunothérapies et jusqu’à 50% - 60% pour le mélanome et le cancer du poumon par l’utilisation de combinaisons thérapeutiques incluant les ICI et les DDA. Le défi actuel des essais cliniques est de développer des stratégies thérapeutiques combinées qui augmentent l’efficacité des différents traitements tout en limitant les résistances. Elucider les mécanismes de résistance est essentiel pour proposer de nouveaux biomarqueurs prédictifs robustes et de nouvelles approches thérapeutiques pour améliorer l'efficacité des ICI.Nous avons émis l'hypothèse que la résistance aux DDA et aux ICI est en partie médiée par des mécanismes tumoraux intrinsèques, dont certains peuvent être partagés. Ainsi, nous avons étudié l'action des DDA et leurs conséquences moléculaires pouvant conduire à une évasion immunitaire. Grâce à trois approches complémentaires (in silico, in vivo sur des cohortes de patients et in vitro), nous identifions que la protéine d'échafaudage p62/SQSTM1 est un médiateur moléculaire clé capable de prédire et de contrôler la sensibilité aux DDA et ICI. Nous soulignons pour la première fois que SQSTM1 est à l’origine d’un profil tumoral immunitaire « CHAUD », tout en régulant à la baisse les mécanismes de réparation de l'ADN. De plus SQSTM1 est essentiel pour la réactivation induite par les DDA des rétrovirus endogènes humains (hERV). En aval, les hERV induisent une réponse antivirale innée, entraînant l'expression d'interférons, MHC-I et PD-L1, conduisant à une évasion immunitaire tumorale.En conclusion, i) nous proposons SQSTM1 comme biomarqueur prédictif pour sélectionner les patients pouvant bénéficier des stratégies de combinaison ICI + DDA, et ii) nous montrons une justification biologique de l'efficacité de telles stratégies dans le cancer du poumon réfractaire, visant à promouvoir leur utilisation et améliorant ainsi le pronostic du CBPNPC
Non-small cell lung cancer (NSCLC) is the deadliest cancer in the world, due to acquired resistance to genotoxic chemotherapy and radiotherapy (DNA-damaging agents, named DDAs hereafter) and targeted therapies. Immunotherapy (including immune checkpoint inhibitors (ICIs)) is a real revolution in patient care. This strategy has indeed had a positive impact, turning into treatable advanced cancers without "actionable" targets that were considered incurable. Survival at 5-year has increased from 5% with conventional treatment to 20% with immunotherapies and up to 50/60% for melanoma and lung cancer with therapies combining ICIs and DDAs. The current challenge in clinical trials is to develop combined therapeutic strategies that increase efficacy while limiting resistance to different treatments. Elucidating resistance mechanisms is essential to propose new robust predictive biomarkers and new therapeutic approaches to improve the efficacy of ICIs.We have hypothesized that resistance to DDAs and ICIs is mediated by intrinsic tumor mechanisms, some of which may be shared. Thus, we have studied the action of DDAs and their molecular consequences that lead to immune evasion. Through three complementary approaches (in silico, in vivo on patient cohorts and in vitro), we identify the p62/SQSTM1 scaffold protein as a key molecular mediator capable of predicting and controlling sensibility to DDAs and ICIs. We report for the first time that SQSTM1 causes a "HOT" tumor immune profile, while downregulating DNA repair mechanisms. In addition, SQSTM1 is essential for the DDAs-induced reactivation of human endogenous retroviruses (hERVs). Downstream, hERVs induce an innate antiviral response, resulting in the expression of interferons, MHC-I and PD-L1, leading to tumor immune evasion.In conclusion, i) we propose SQSTM1 as a predictive biomarker for selecting patients who may benefit from ICI plus DDA combination strategies, and ii) we highlight a biological rationale for the efficacy of such strategies in refractory lung cancer, aimed at promoting their use and thus improving the prognosis of NSCLC

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Schjenken, John Even. "Human endogenous retroviruses and immune tolerance in pregnancy." Thesis, 2011. http://hdl.handle.net/1959.13/923742.

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Research Doctorate - Doctor of Philosophy (PhD)
The human placenta expresses endogenous retroviral envelope proteins which have been postulated to play an important role in the physiology of pregnancy. Of these, syncytin-1 and syncytin-2 are highly expressed in the syncytiotrophoblast and cytotrophoblast respectively and are thought to be key factors in the regulation of syncytialisation due to their fusiogenic properties. In addition to their role in cell fusion, it has also been speculated that syncytin-1 and syncytin-2 may have a role in maternal immune tolerance due to the presence of the highly conserved immunosuppressive domain (ISD) within its sequence. However, no studies are yet to confirm this putative role. Another factor which has been speculated to have a role in maternal immune tolerance is Corticotropin Releasing Hormone (CRH) which has been shown to promote implantation and the maintenance of early pregnancy via the regulation of FasL. Interestingly, both syncytin-1 and FasL have been identified in immunosuppressive placental exosomes. Since CRH stimulates cyclic AMP (cAMP) production and syncytin-1, syncytin-2 and FasL are all stimulated by the cAMP second messenger pathway, it was hypothesised that syncytin-1 and syncytin-2 may be regulated by CRH. Further, it was hypothesised that syncytin-1 may contribute to the modulation of the maternal immune environment during pregnancy. To examine the regulation of syncytin-1 and syncytin-2 by CRH, a combined nucleic acid and protein extraction procedure was developed using column based nucleic acid extraction kits. Using 2D buffer, proteins extracted using this method were shown to have a comparable protein profile to conventionally extracted proteins. This method was then used to examine RNA and protein levels in CRH treated BeWo cells. Following CRH treatment of BeWo cells, a significant upregulation of syncytin-1, syncytin-2 and FasL mRNA was observed. CRH also increased the production of the syncytin-1 precursor in an exosomal fraction. To examine the immunosuppressive properties of syncytin-1, the recombinant ectodomains of human and mouse syncytins were produced and purified using a combination of affinity chromatography and gel filtration. The immunosuppressive properties of the syncytin-1 recombinant ectodomain were then tested using a whole blood culture model stimulated with LPS or PHA. Syncytin-1 recombinant ectodomain at a concentration of 1µM inhibited the production of TNF-α by 50% and CXCL10 by 65% in whole blood cultures following maximal stimulation with LPS. Syncytin-1 recombinant ectodomain also inhibited the production of IFN-γ by 30% in PHA stimulated PBMC. These studies demonstrate for the first time that syncytin-1 has immunosuppressive properties. Further, these studies show that CRH has a role in the stimulation of syncytin-1 and its subsequent sorting into exosomes. Circulating placental exosomes containing syncytin-1 and other immunosuppressive factors including FasL may interact with maternal immune cells to prevent an immune response against the fetal-placental unit. This is a novel mechanism that may contribute to our understanding of how a genetically different fetus can be tolerated by the mother during pregnancy.

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Lung, Chao Meng, and 趙孟隆. "Functional study of human endogenous retrovirus HERV-Ia LTR-like hancer." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/84198401235766840404.

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Goodchild, Nancy L. "The impact of endogenous retrovirus-like sequences on the human genome." Thesis, 1993. http://hdl.handle.net/2429/6917.

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Transposable elements comprise ~10% of the human genome and are hypothesized to play a significant role in genome variability and gene regulation. My work has focused on the RTVL-H family of human endogenous retroviruses and the possible impact these elements may have had and continue to have on the human genome. The evolutionary history of the RTVL-H family within the primate lineage was examined using several approaches. My findings suggest that the RTVL-H family has undergone two successive waves of amplification during primate evolution. The major amplification of RTVL-H elements appears to have occurred very early within the Old World primate lineage, after its divergence from the New World monkeys. The genomes of humans, apes and Old World monkeys are estimated to contain 50-100 copies of undeleted elements and 800-1000 copies of deleted sequences. This is in contrast to the New World monkey, marmoset, genome which contains only a handful of intact elements and ~50 deleted sequences. A second expansion of deleted elements appears to have occurred within a common ancestor of the ape lineage and was associated with a novel long terminal repeat (LTR) subtype. The structure of RTVL-H elements and their distribution in the genome suggest that RTVL-H elements amplified via retrotransposition. I have found evidence for this through the identification of an RTVL-H element in the orangutan genome that appears to represent the reverse transcription and integration of a spliced RTVL-H transcript. An apparent spliced genomic element found in human DNA lacks an intact 5’ LTR and may represent a processed RTVL-H pseudogene. This element appears to be polymorphic in the human population. I have also laid the ground work for a strategy to demonstrate RTVL-H retrotransposition within an experimental time frame. This strategy uses a “retro- transposition indicator gene” and allows for the direct selection of a retrotransposition event. RTVL-H LTRs contain transcriptional regulatory sequences and thus may affect the expression of adjacent cellular sequences. I have identified a clone, termed cPj-LTR, containing an ORF of 223 aa that has been polyadenylated within an RTVL-H LTR. The corresponding gene, termed PLT, is a novel, multi-exon locus that appears to have been evolutionarily conserved. Northern analysis identified several PLT-related transcripts in placental RNA samples, one of which appears to be associated with the LTR. The presence of this PLT-LTR fusion transcript was confirmed by PCR. Analysis of additional PLT cDNA clones suggests that the PLT mRNA undergoes alternative splicing at its 3’ end, with polyadenylation within an RTVL-H LTR occurring in one of the resulting transcripts.

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Chang, Nien-Tzu, and 張念慈. "Study on the Transcriptional Regulation of Human Endogenous Retroviruses and their Pathogenic Potentials." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/55626230751393070845.

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博士
國防醫學院
生命科學研究所
96
Endogenous retroviruses have a wide distribution within vertebrates; they are present in multiple copies dispersed throughout the genomes of host species. Human endogenous retroviruses (HERVs) constitute about 8% of the human genome. The prevalence and maintenance of HERVs elements suggest that they may play a role in the biology of the host species. HERVs are related to retroviruses with their characteristic LTR-gag-pol-env-LTR structure, in which LTRs possess the enhancer and the promoter functions for RNA transcription, viral integration and polyadenylation. Transcriptional activation of HERVs is supposed to be potentially pathogenic for producing retroviral proteins and RNA copies to form virus particles, proceeding to retro-transposition and insertion mutagenesis, altering the expression of neighboring or distant cellular genes from the insertion sites and eventually leading to neoplastic transformation or genetic disease. In most cases, HERVs are either structurally defective or inactive due possibly to stringent negative control mechanisms. Since RNA transcripts of HERV-I in various human cancer cells were hardly detectable by Northern blots in our preliminary studies, we isolated the LTR of RTVL-Ia and constructed site-specific mutations for analysis of the promoter and enhancer functions by using chloramphenicol acetyl transferase (CAT) reporter assay. Our results showed that 5’-LTR of HERV-I possess bi-directional promoter activity and unidirectional enhancer activity. The ATAAAAA element, a TATA-like box, in 5’-LTR mainly exerts a promoter function while the CCAAT element exhibits a partial enhancer function, and these two elements in the LTR apparently provide maximum transcriptional activity. Therefore, the poor transcriptional activity of HERV-I LTR may be due to the AGTAAA segment at the presumed polyadenylation site which plays a negative regulatory role in controlling gene expression. P53 is a tumor suppressor protein, and its mutations are the most frequently reported genetic alterations in human cancers. P53 has been shown to repress or activate the transcription activity of several cellular and viral promoters, although its effect on HERVs is not known. We have found that wild type (wt) p53 can efficiently repress the transcriptional activity of HERV-I LTR presumably through the interaction of wtp53 with the TATA-binding proteins or CAAT-binding proteins. In addition, mutantp53(V143A) can more or less stimulate the transcriptional activity of HERV-I LTR. These results imply that, following p53 mutation, LTRs are likely to be activated and might aberrantly regulate their neighboring cellular genes during the tumor progression processes. To study the possible involvement of p53 in chromosomal HERV expression, we further examined the RNA transcripts of HERV-E, HERV-H, HERV-I, HERV-K and HERV-W multi-gene families in p53-null Saos-2 cells transfected with wtp53 or “hot-spot” site-specific p53 mutants. Quantitative real-time PCR analysis showed that limited RNA expression of these HERVs in Saos-2 cells were not affected by wtp53 but could be elevated by mtp53(D281G), through transient or stable transfection. 5-Azacytidine and trichostatin A, known to activate endogenous retroviruses in other animals, did not induce HERV expression in the parental Saos-2 cells or wtp53 transfectants but could additively increase HERV genes expression especially in cells stably transfected with mtp53(D281G). Our results suggest that the stringent controlled chromosomal HERV genes may be compromised by p53 mutation, especially at codon 281, in combination with epigenetic chromatin alterations, leading to the activation of potentially pathogenic retrotransposable gene functions.

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49

Liao, Chao Ching, and 廖昭晴. "Molecular Investigation and Multiple Factors Analysis of Human Endogenous Retroviruses in Juvenile Rheumatoid Arthritis." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/08613770156837071655.

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碩士
長庚大學
醫學生物技術暨檢驗學系
98
Human endogenous retroviruses (HERVs) represent a class of interspersed mobile repetitive elements in human genome which comprised 8% of whole human genome. HERVs have been suggested as potential etiological agents and cofactors in chronic diseases such as autoimmune diseases, particularly in rheumatic diseases. However, the exactly role of HERVs in rheumatic diseases is still unclear. This study focused on the elucidation of the role of HERVs in human genome and its associated characteristics with human autoimmune diseases, especially in juvenile rheumatoid arthritis (JRA). HERV-K is one of the most completed sequence including LTR-gag-pol-env-LTR and open reading frame in HERV family. HERV-K has potential ability to produce viral protein or even package viral particle. The aim of this study was to study copy number and gene expression of HERV-K from peripheral blood mononuclear cells between JRA patients and controls. Our hypothsis was that there could have copy number, gene expression variations, and insertional polymorphisms of HERV-K family. Besides geneneral HERV-K family study, we also focused on HERV-K10 and HERV-K18 which have been mentioned to be important in autoimmune diseases in previous studies. Real-time quantitative PCR was performed to detect HERV-K structure protein genes, gag and env, and non-structure protein gene, pol. Tradictional PCR was performed to detect HERV-K10/K18 insertional polymorphism. For HERV-K copy number study, the results showed that there was no significant difference between all JRA patients, without subgrouping, and controls. But if we looked at subgrouping results, in male samples, there was significantly decrease of HERV-K gag and pol copy number in JRA patients, particular in pauciarticular JRA. Instead of male samples, there was significantly increase of HERV-K gag copy number in female JRA patients. For insertional polymorphism study, we did not found any polymorphisms from HERV-K10 and HERV-K18 in JRA patients and controls. In gene expression level, we found that there was significantly HERV-K gag and env mRNA decrease but significantly increase of HERV-K pol mRNA expression in JRA patients, especially in male JRA samples. There was significantly increase of HERV-K10-like gag and HERV-K18-like env gene expression in JRA patients. In this study, we demonstrated the first time that HERV-K gene expression level by detecting HERV-K’s three major gene segments. Our data conclude that there was a strong association of HERV-K family copy numbers and expression difference between JRA patients and healthy controls. Our results can contribute to the elucidatation of the JRA mechnisme, but further studies need to be done.

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50

Passos, Vânia Patrícia Mendes. "Expression and regulation of human endogenous retroviruses (HERVs) in developing and mature T cells." Master's thesis, 2015. http://hdl.handle.net/10451/20853.

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Tese de mestrado, Biologia (Biologia Molecular e Genética), Universidade de Lisboa, Faculdade de Ciências, 2015
The Human genome comprises almost 8% long terminal repeat (LTR)-retroelements, in which Human Endogenous Retroviruses (HERVs) are included. More than 30 HERV groups have been identified. They share a similar provirus structure with exogenous retroviruses, despite harboring many inactivating mutations. Interestingly, HERVs have been increasingly associated with cancer, autoimmunity and infectious diseases. Data on HERV expression in T cells is sparse. Here we investigated, for the first time, the expression of several HERV families during human T cell development and differentiation. HERV-K, -W, -P and -R envelope (env) expression were analyzed in purified T cell subsets from the human thymus, peripheral blood or tonsils using real time RT-PCR. In addition, Env protein expression was studied in thymic and tonsillar tissue using immunohistochemistry. We observed a similar pattern of HERV env transcriptional expression during the development and maturation of thymocytes in the thymus. HERV levels tended to be higher in mature thymocytes than in the early developmental stages, supporting their differential regulation during T cell development. Regarding the peripheral blood compartment, HERVs showed similar transcriptional levels within naïve and memory CD4 and CD8 T cells, with small inter-individual variation. Moreover, HERV expression was modulated during T follicular helper (TFH) differentiation in human tonsils. Importantly, we further confirmed Env protein production in lymphoid tissues, as HERV-K Env protein was expressed in the medullary compartment of the thymus, as well as in the T cell zone of the tonsil. Our data regarding HERV env expression profiles during T cell development and maturation prompted us to test potential pathways of HERV regulation. We demonstrated, using real time RT-PCR, that T cell receptor (TCR) stimulation and Phorbol-12-myristate-13- acetate (PMA)-Ionomycin were able to down-regulate HERV-W, -P and -R transcriptional levels in CD4SP thymocytes. Additionally, a positive correlation was found between HERV env expression and the transcriptional levels of the retroviral restriction factor deoxycytidine deaminases apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G (APOBEC3G) throughout T cell development and differentiation, which was not observed for APOBEC3F. Overall, our data support a tight regulation of HERV expression during T cell development and differentiation. This appears to be particularly pertinent in the thymus, with possible implications for the process of T cell selection.
O genoma humano é composto por aproximadamente 8% de retroelementos contendo repetições terminais longas (LTRs), nos quais se incluem os Retrovírus Endógenos Humanos (HERVs). Os HERVs são sequências de ADN que se fixaram no genoma humano após uma primeira infeção da linha germinativa por um retrovírus exógeno, sendo subsequentemente transmitidos verticalmente. A sua diversidade depende das interações com o hospedeiro, no entanto somente alguns HERVs foram capazes de persistir, sofrendo mutações e deleções que resultaram na perda da capacidade de replicação. Os HERVs dividem-se em mais de 30 famílias e 3 classes, de acordo com a sua homologia a retrovírus exógenos, sendo denominados pela letra que define o ácido ribonucleico de transferência (tRNA) usado para a transcrição reversa do seu genoma. Apesar de a maioria dos HERVs estar defetivo, vários estudos demonstraram a expressão de RNA e de proteína em vários tecidos humanos e linhas celulares, e em raras situações a produção de partículas virais intactas. Pensa-se que eles persistiram no genoma humano por duas razões: exercerem funções biológicas ou devido à incapacidade de o hospedeiro os eliminar. Curiosamente, apenas a função das proteínas do invólucro (Env) do HERV-W e HERV-FRD é reconhecida. Por outro lado, o estudo dos HERVs num contexto de doença tem aumentado, uma vez que eles têm sido associados com a ocorrência de cancro, autoimunidade e doenças infeciosas. Como não podemos excluir a existência de um HERV infecioso, é importante perceber o que pode regular a sua expressão. Canonicamente, a sua transcrição depende dos seus promotores. No entanto esta pode ser igualmente ativada por fatores de transcrição celulares (i.e., NF-κB) ou proteínas virais. Posto isto, o hospedeiro desenvolveu mecanismos para controlar a sua expressão. O enzima “apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like” 3G (APOBEC3G) e outros membros da família das citidina desaminases foram descritos como fatores de restrição virais em células humanas, atuando sobre a replicação de retrovírus, tais como o HIV e alguns HERVs. Sabe-se igualmente, que a sua transcrição é reprimida por mecanismos de metilação do DNA, modificação das histonas e RNA de interferência, no entanto os estudos em humanos são limitados. A eficiência do sistema imunitário depende da resposta da imunidade inata e adaptativa para eliminar invasões patogénicas. A imunidade inata representa a primeira linha de defesa, sendo constituída pela barreira epitelial, proteínas solúveis e moléculas bioativas. Subsequentemente, a imunidade adaptativa atua pelo reconhecimento específico de antigénios. Este reconhecimento é feito usando receptores antigénicos expressos à superfície de linfócitos B e T. No entanto, para esta resposta se dar corretamente, as células B e T têm de submeter-se a vários processos de seleção e maturação. Progenitores de células T expressando CD34+ migram da medula óssea para o timo, onde irá ocorrer o desenvolvimento e maturação das células T. Os timócitos serão distinguidos de acordo com a expressão dos corecetores CD4 e CD8, em: timócitos “triple negative” CD34+ (TN CD34+, CD4-CD8-CD3-), timócitos CD4 “immature single positive” (CD4ISP, CD4+CD8-CD3-), timócitos “double positive” (DP, CD4+CD8+CD3-/+), e timócitos CD4 ou CD8 “single positive” (SP, CD4+/-CD8-/+CD3+). Durante o processo de maturação e seleção, os timócitos sofrem rearranjo do recetor de células T (TCR) β e α. Interações de baixa afinidade entre o TCRαβ de timócitos DP e péptidos do próprio complexados com antigénios no complexo major de histocompatibilidade (MHC) são selecionados positivamente. Por outro lado, a seleção negativa ocorre se esta afinidade for demasiado alta. Timócitos selecionados positivamente diferenciam-se em células T CD4SP ou CD8SP, que após maturação migram para a periferia. Na periferia, as células T “naïve” circulam através dos órgãos linfóides secundários (p.ex. amígdalas) até sofrerem ativação, processo que envolve o encontro de antigénios apresentados por células dendríticas e o sinal co-estimulator emitido pelas mesmas (CD28). Após ativação, estas células adquirem uma das funções efetoras de células T auxiliar: Th1, Th2, Th17, Th9, T folicular auxiliar ou T reguladora. Em contrapartida, as células T CD8 “naïve” diferenciam-se em citotóxicas (CTLs). Sabe-se que, 5-10% das células T CD4 e CD8 efetoras persistem como células T de memória, caracterizadas por oferecer uma maior e mais eficiente resposta após segunda exposição antigénica. A expressão dos HERVs em células T tem sido pouco estudada. Neste projeto foi investigado, pela primeira vez, a expressão de várias famílias dos HERVs durante o desenvolvimento e diferenciação de células T. A expressão do gene env do HERV-K, -W, -P e -R foram analisadas em subpopulações de células T purificadas do timo humano, sangue periférico e amígdalas, usando Real Time RT-PCR. Paralelamente, foi avaliada a expressão da proteína Env em tecido do timo e amígdalas usando imunohistoquímica (IHQ). Os resultados revelaram um padrão semelhante de expressão génica dos HERVs durante o desenvolvimento e maturação dos timócitos no timo. Os níveis transcricionais apresentaram uma tendência para serem maiores nas fases mais desenvolvidas (CD4SP e CD8SP) do que nas fases iniciais do desenvolvimento (TN CD34+ e CD4ISP), indicando que possam estar a ser distintamente regulados. Estudos de vários grupos podem explicar este padrão. Conrad e colegas identificaram a expressão no timo humano de superantigénios codificados pelo membro HERV-K18, na fase DP com o intuito de induzir a seleção negativa de timócitos CD4 Vβ7. Adicionalmente, sabe-se que o desenvolvimento de células T no timo é altamente regulado por mecanismos epigenéticos; nas fases iniciais do desenvolvimento o DNA encontra-se hipermetilado, ao passo que ao longo da maturação e seleção o DNA torna-se hipometilado. Os HERVs são reprimidos com a metilação do DNA, por isso é possível especularmos que estes mecanismos possam explicar o padrão de expressão dos HERVs no desenvolvimento dos timócitos. Relativamente à periferia, vários estudos analisaram os níveis de HERVs em células mononucleares totais do sangue periférico. Neste projeto analisamos os seus níveis em subpopulações do sangue periférico. Os HERVs revelaram níveis transcricionais similares entre células T CD4 e CD8 “naïve” e de memória, variando pouco entre os indivíduos analisados. Podemos nesse caso especular que, o processo de proliferação homeostático envolvido na manutenção das populações “naïve” e de memória não afeta a expressão dos HERVs. Adicionalmente, a atividade transcricional dos HERVs parece ser modulada nas amígdalas durante a diferenciação de células T foliculares auxiliares. Apesar do estudo dos HERVs em órgãos linfóides secundários ser inexistente, pensamos que esta modulação se deve à ativação e ação de mecanismos regulatórios que reprimem especificamente a transcrição dos diferentes HERVs durante a diferenciação celular. É importante referir que os resultados da IHQ confirmaram a expressão da proteína Env do HERV-K no timo (medula) e na amígdala (zona das células T), e apoiam os dados obtidos na análise da expressão génica. Os dados gerados durante o desenvolvimento das células T no timo, levou-nos a investigar os possíveis mecanismos de regulação da transcrição dos HERVs. Conseguimos demonstrar, usando Real Time RT-PCR, que a estimulação por via de TCR e “PMAIonomycin” foi capaz de regular negativamente a expressão do HERV-W, -P e -R em timócitos CD4SP. Adicionalmente, observamos uma correlação positiva entre os níveis transcricionais dos HERVs e do fator de restrição APOBEC3G ao longo do desenvolvimento e diferenciação de células T, mas não com o enzima APOBEC3F. Efetivamente, parece que os mecanismos que controlam os níveis dos HERVs são específicos da célula ou população celular em que eles se expressam. Em suma, os nossos resultados indicam que os HERVs são estritamente regulados durante o desenvolvimento e diferenciação das células T. Esta regulação aparenta ser mais relevante no timo, com implicações no processo de seleção das células T.

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Dissertations / Theses on the topic 'Human endogenous retroviruse'

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