Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Sox2 transcription factor.
Thèses sur le sujet « Sox2 transcription factor »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleures thèses pour votre recherche sur le sujet « Sox2 transcription factor ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les thèses sur diverses disciplines et organisez correctement votre bibliographie.
1
Lins, Katharina. « Regulation of POU transcription factor activity by OBF1 and Sox2 ». Thesis, Open University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402625.
Texte intégralRésumé :
For a cell to exert a specialized function certain genes have to be expressed, others repressed. Transcription factors, regulating this expression, do not function alone, but are often part of multi-protein complexes. Regulating a single gene with more than one transcription factor is an efficient way to integrate responses to a variety of signals using a limited number of proteins. DNA binding proteins often interact with each other and with non-DNA binding proteins in a specific arrangement. The assembly of these complexes is often highly cooperative and promotes high levels of transcriptional synergy. The center of my thesis is the family of POU transcription factors. Specifically, I elaborate the interaction within the POU protein family, with members of other transcription factor families and with cofactors. In all cases, the assembly of the correct array of polypeptides on the DNA requires specific protein-protein and protein-DNA interactions. As an example of POU factors interacting with each other and with a cofactor I investigated the properties of a protein-DNA complex with the B-cell-specific cofactor OBF! and the Octl dimer. Depending on the DNA sequence they bind to, Octl dimers are arranged in configurations that are either accessible (PORE sequence) or inaccessible (MORE sequence) to OBF!. In Chapter 3 I show that the expression of Osteopontin, which contains a PORE sequence in its enhancer region, depends on the presence of OBFI in B-cells. OBFI alleviates DNA sequence requirements of the Octl dimer on PORE-related sequences in vitro. Furthermore, OBFI enhances POU dimer-DNA interactions and overrides Oct! interface mutations, which abolish PORE-mediated dimerization without OBFl. Based on the biochemical data, I propose a novel Oct! dimer arrangement when OBF 1 is bound. As an example of Oct factors interacting with members of another transcription factor family I studied the interactions of Sox2 with Octl and Oct4, respectively. POU and Sox transcription factors exemplify partnerships established between various transcriptional regulators during early embryonic development. The combination of Oct4 and Sox2 on DNA is considered to direct the establishment of the first three lineages in the mammalian embryo. Although functional cooperativity between key regulator proteins is pivotal for milestone decisions in mammalian development, little is known about the underlying molecular mechanisms. The data in Chapter 4 validate experimental highresolution structure determination, followed by model building. The study shows that Oct4 and Sox2 are able to dimerize on DNA in distinct conformational arrangements. The binding site characteristics of their target genes are responsible for the correct spatial alignment of the Velcro-like interaction domains on their surface. Interestingly, these surfaces frequently have redundant functions and are instrumental in recruiting various interacting protein partners. In Chapter 5 I investigated how Sox2 and Oct4 regulate transcription of a target gene. The first intron of Osteopontin contains a Sox-binding site and a unique PORE to which Oct4 can either bind as a monomer or a dimer. The study reveals that Sox2-specific repression depends on an upstream Sox site and an intact PORE, although neither the Sox nor the PORE sites are negative elements on their own. A mechanism is being proposed how Sox2 represses Oct4-mediated activation of Osteopontin.
2
Rosso, Michele <1984>. « Role of the Transcription Factor Sox2 in the Osteogenic Lineage ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6489/4/rosso_michele_tesi.pdf.
Texte intégralRésumé :
The Sox2 transcription factor is modified by sumoylation at the K247 position although the addition of SUMO1 and Pias1 promotes the sumoylation of Sox2 at the additional K123 site. The role of sumoylation on Sox2 biological functions was analyzed by comparing the activity of WT and sumoylation mutants on the transcription of the FGF4 gene in HeLa cells and on the downregulation of the Wnt pathwayvin 293T cells. When SUMO1 and PIAS1 promote the sumoylation of WT Sox2, the transcriptional activity of the FGF4 promoter is inhibited showing that Sox2 sumoylation is necessary for the repression function. However, there is no effect of Sox2 sumoylation on β-Catenin activity.
Since we were interested in osteoblast differentiation we set up an inducible system for Sox2 in primary osteoblasts. Following Sox2 doxycycline induction, 158 genes were differentially expressed: 120 up-regulated and 38 down-regulated. We annotated as direct Sox2 targets a number of genes involved in osteoblast biology and we further analyzed 3 of them involved in the BMP pathway. The results show that Sox2 regulates the BMP pathway without affecting SMAD phosphorylation, and that Sox2 sumoylation is not necessary for this function.
We also found that genes involved in the Hippo pathway were direct Sox2 targets. As the Hippo pathway is activated by Sox2 and Sox2 interacts with the NF2 promoter, we checked the effect of Sox2 on the expression of NF2. We showed that Sox2 down-regulates the transcriptional activity of the NF2 promoter, allowing the transcription of the YAP/TEAD genes in osteoblasts, thus acting as an upstream regulator of the Hippo pathway. We conclude that Sox2 induction in osteoblasts triggers FGF dependent inhibition of the BMP, Wnt and Hippo pathways.
3
Rosso, Michele <1984>. « Role of the Transcription Factor Sox2 in the Osteogenic Lineage ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6489/.
Texte intégralRésumé :
The Sox2 transcription factor is modified by sumoylation at the K247 position although the addition of SUMO1 and Pias1 promotes the sumoylation of Sox2 at the additional K123 site. The role of sumoylation on Sox2 biological functions was analyzed by comparing the activity of WT and sumoylation mutants on the transcription of the FGF4 gene in HeLa cells and on the downregulation of the Wnt pathwayvin 293T cells. When SUMO1 and PIAS1 promote the sumoylation of WT Sox2, the transcriptional activity of the FGF4 promoter is inhibited showing that Sox2 sumoylation is necessary for the repression function. However, there is no effect of Sox2 sumoylation on β-Catenin activity.
Since we were interested in osteoblast differentiation we set up an inducible system for Sox2 in primary osteoblasts. Following Sox2 doxycycline induction, 158 genes were differentially expressed: 120 up-regulated and 38 down-regulated. We annotated as direct Sox2 targets a number of genes involved in osteoblast biology and we further analyzed 3 of them involved in the BMP pathway. The results show that Sox2 regulates the BMP pathway without affecting SMAD phosphorylation, and that Sox2 sumoylation is not necessary for this function.
We also found that genes involved in the Hippo pathway were direct Sox2 targets. As the Hippo pathway is activated by Sox2 and Sox2 interacts with the NF2 promoter, we checked the effect of Sox2 on the expression of NF2. We showed that Sox2 down-regulates the transcriptional activity of the NF2 promoter, allowing the transcription of the YAP/TEAD genes in osteoblasts, thus acting as an upstream regulator of the Hippo pathway. We conclude that Sox2 induction in osteoblasts triggers FGF dependent inhibition of the BMP, Wnt and Hippo pathways.
4
MARIANI, JESSICA. « Transcriptional regulation, target genes and functional roles of the SOX2 transcription factor in mouse neural stem cells maintenance and neuronal differentiation ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2009. http://hdl.handle.net/10281/8321.
Texte intégralRésumé :
The aims of this PhD research were: to examine molecular mechanisms underlying the transcriptional regulation of the Sox2 gene during forebrain development; to examine the role of Sox2 for the proper neuronal differentiation of neural stem cells; and to examine the role of Sox2 in controlling the maintenance of neural stem cells (in vivo and in vitro).
The aim of the first work (Chapter 1) was to investigate the transcription factors and the regulatory sequences that control transcription of the Sox2 gene in the developing brain and neural stem cells. Our laboratory previously identified Sox2 regulatory sequences able to drive expression of a reporter β-geo transgene to neural stem cells of the brain in transgenic mice. I focused on two mouse forebrain-specific enhancers able to recapitulate Sox2 telencephalic expression throughout forebrain development, also active in neural stem cells of the adult and embryonic brain (Sox2 5’ and 3’ enhancers). This work showed that Emx2 acts as a direct transcriptional repressor of both Sox2 telencephalic enhancers, acting in two different ways to repress their transcriptional activity: by directly binding to a specific site within these regulatory elements, thus preventing the binding of activators, or possibly by protein to protein interaction sequestring the activators, thus antagonizing their activity. By the study of double mutant mice (expressing reduced levels of Sox2 and Emx2) we further found that Emx2 deficiency counteracts (at least in part) the deleterious effects of Sox2 deficiency on neural stem cell proliferation ability in the postnatal hippocampus, and also rescued other brain morphological abnormalities of Sox2-deficient mutants. It is likely possible that a simultaneous decrease of Emx2 levels (a Sox2 repressor) may antagonize these defects, by restoring Sox2 levels.
In the second line of my research (Chapter 2) we performed in vitro differentiation studies on neural stem cells cultured from embryonic and adult brains of Sox2 “knockdown” mutants (expressing reduced levels of Sox2) where Sox2 deficiency impairs neuronal differentiation. In particular, my contribution to this work was to evaluate the in vitro differentiation defects of Sox2 mutant neurospheres by immunofluorescence staining for different glial and neuronal markers. Strikingly, I observed that mutant cells produce reduced numbers of mature neurons (in particular GABAergic neurons), but generate normal glia. Most of the cells belonging to the neuronal lineage failed to progress to mature neurons showing morphological abnormalities. To evaluate if restoration of Sox2 levels is able to rescue the differentiation defects of mutant cells, I engineered Sox2-expressing lentiviral vector, which I used to infect neural cells at early or late differentiation stages. I found that, Sox2 overexpression is able to rescue the neuronal maturation defects of mutant cells only if administered at early stages of differentiation. Further, I observed that Sox2 suppresses the endogenous GFAP gene, a marker of glial differentiation. These results suggests that Sox2 is required in early in vitro differentiating neuronal cells, for maturation and for suppression of alternative lineage markers.
The third research (Chapter 3) investigated neurogenesis and neural stem cells properties in mice carrying a conditional mutation in the Sox2 gene (Sox2flox). Here, Sox2 was deleted via a nestin-Cre transgene that leads to complete Sox2 loss in the central nervous system by 12.5 dpc. These studies showed that embryonic neurogenesis was not importantly defective, however shortly after birth, NSC and neurogenesis are completely lost in the hippocampus. The expression of cytokine-encoding genes, essential for stem cell niche, is also strongly perturbed and leads to impaired stem cell maintenance (in vivo and in vitro). In vitro, NSC cultures derived from Sox2-deleted forebrain become rapidly exhausted, losing their proliferation and self-renewal properties. In Sox2-deleted neurospheres, Shh is extremely downregulated. However, the conditioned medium from wild type NSC cultures or the administration of a Shh agonist efficiently rescue the proliferation defects. These results suggest that the effect of Sox2 on neural stem cells growth and maintenance is partially mediated by Shh secretion, and that the Shh gene must be a direct target of Sox2. To confirm this hypothesis, I infected Sox2-deleted NSC with a Sox2-IRES-GFP expressing lentivirus just prior to the beginning of the growh decline, and I observed that the re-expression of Sox2 induces the ability to re-express Shh and rescues the formation of neurosphere. These findings indicate that NSC control their status, at least in part, through non cell-autonomous mechanisms (such as activation of important cytochine-encoding genes) which depend on Sox2.
5
Hütz, Katharina Antonia. « The role of the transcription factor SOX2 in tumorigenesis and development of the stomach ». Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-175561.
Texte intégral
6
BADIOLA, SANGA ALEXANDRA. « Study of the role of the SOX2 transcription factor in neural and mammary cancer stem cells using SOX2 conditional knock-out in mouse ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/52431.
Texte intégralRésumé :
The stem cell-determining transcription factor Sox2 is required for the maintenance of normal stem cells. In this study, we investigated the requirement for Sox2 in neural and breast cancer stem-like cells. In the first case, using a conditional genetic deletion mutant in a mouse model of platelet-derived growth factor-induced malignant oligodendroglioma. Taken together, our results showed that Sox2 is essential for tumor initiation by mouse pHGG cells, and we illustrated a Sox2-directed strategy of immunotherapy to eradicate tumor-initiating cells. In the second case, we used a Sox2 conditional deletion by an MMTV-Cre transgene (active in mammary tissue) to address Sox2 requirement within a widely studied mouse model of mammary tumor, produced by expression of a transgene encoding a mutated ErbB2/Neu oncogene, driven to mammary tissue by the MMTV promoter. Our results point to a heterogeneity within mammary tumors regarding Sox2 expression and function, in particular within ErbB2/Neu-positive tumors, that it will be important to consider when hypothesizing therapy approaches.
7
CACCIA, ROBERTA. « Defects in neuronal differentiation and axonal connectivity in mice mutant in the Sox2 transcription factor gene : in vitro and in vivo studies ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2010. http://hdl.handle.net/10281/10334.
Texte intégralRésumé :
Sox2 is an important transcription factor expressed in the central nervous system from the beginning of its development. We generated Sox2 mutant mice carrying a “knockdown” mutation together with a null mutation, which express 20-30% of the normal amount of Sox2. These mice show brain abnormalities including decreased cortical size, defects in neurogenesis and cell death in thalamus (Ferri et al., 2004). We also generated Sox2 conditional mutant mice, in wich the Sox2 locus is flanked by loxP sites, and it can be ablated by driven expression of a Cre recombianse. These mice show brain abnormalities including e decreased size of posterior cortex. (Favaro et al.). Around the time of neurogenesis, neocortex and dorsal thalamus start to become connected through reciprocal axonal projections. The complete process in mice occurs between E13 and E18. I hypothesize that in Sox2 mutants the thalamocortical and corticothalamic connections may be affected. I studied if the cortical neurons are able to grow and form correct connections in Sox2 hypomorphic mice and in conditional Sox2 mutant mice, in which Sox2 in completely ablated in the central nervous system from E12,5 via a Nestin Cre transgene, or is deleted from specific regions of the brain via Cre driven by genes specifically expressed in cortex or thalamus
8
BERTOLINI, JESSICA ARMIDA. « Functional characterization of regulatory sequences targeted by the transcription factor SOX2, identified by studies of long-range chromatin interactions in brain-derived neural stem/precursor cells ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/83922.
Texte intégralRésumé :
Sox2 codifica per un fattore trascrizionale necessario per la pluripotenza delle cellule staminali embrionali.
Mutazioni eterozigoti in Sox2 nell’uomo causano difetti nello sviluppo dell’occhio (anoftalmia, microftalmia) e dell’ippocampo, con insorgenza di patologie come epilessia, problemi nel controllo motorio e difetti di apprendimento.
Tramite “knock-out” condizionale di Sox2 in topo, abbiamo osservato l’importanza di Sox2 per lo sviluppo del cervello e per il “self-renewal” delle staminali neurali.
Di recente è emerso che elementi regolatori possono trovarsi molto lontano dai geni che controllano lungo il cromosoma. Mutazioni in tali elementi talvolta causano patologie dovute a deregolazione del gene associato.
In collaborazione con la Dr. C.-L. Wei (California), abbiamo comparato le interazioni “long-range” nella cromatina di cellule di precursori neurali (NPCs) di topi “wild-type” (wt) e Sox2-deleti, usando la tecnica ChIA-PET: su 7000 interazioni mappate in NPCs wt, 2700 erano perse in NPCs Sox2-delete. Tra queste 2700 interazioni, molte coinvolgevano geni legati allo sviluppo neurale e sequenze identificate come enhancer telencefalici per la presenza di siti di legame per p300.
Abbiamo poi determinato la mappa genomica dei siti di legame per SOX2 nella cromatina di NPCs wt (in collaborazione con il Dr. F. Guillemot; Londra). Circa metà delle interazioni “long-range” SOX2-dipendenti presentava un picco di ChIP-seq per SOX2, suggerendo un ruolo diretto di SOX2 nel loro mantenimento.
Il mio progetto di tesi intende definire se sequenze distali, associate in modo SOX2-dipendente a geni neurali (candidati “target” per SOX2), sono elementi di regolazione trascrizionale attivi durante lo sviluppo embrionale del cervello e se la loro attività è regolata da SOX2.
Abbiamo selezionato 13 putativi elementi regolatori distali (DREs), tra le interazioni ChIA-PET perse nelle NPCs Sox2-delete, per caratterizzarli funzionalmente in esperimenti di transgenesi in zebrafish. Ho condotto questi esperimenti in vivo nel laboratorio della Dr. P. Bovolenta a Madrid, supportata da una “EMBO short-term fellowship”.
Abbiamo clonato le 13 DREs in un plasmide (ZED), a monte di un promotore minimo e del gene GFP. Il plasmide è stato iniettato in embrioni allo stadio di 1 cellula e il DNA si è integrato nel genoma di pesce. Gli embrioni sono stati osservati durante lo sviluppo per analizzare se, e dove, la sequenza testata guidava l’espressione di GFP. La GFP era espressa riproducibilmente in 12 DREs su 13 nel cervello in via di sviluppo e/o in regioni neurali più posteriori, sovrapponendosi al pattern di espressione del gene associato. Ciò indica che i DREs da soli guidano l’espressione del gene reporter. Ho quindi selezionato embrioni GFP+ transienti (F0) di 8 DREs per ottenere linee transgeniche stabili F1.
Per testare se l’attività enhancer dei DREs è regolata da SOX2, ho usato un approccio “perdita di funzione”. Ho iniettato un oligonucleotide antisenso (morfolino), specificamente diretto contro l’mRNA di Sox2, in embrioni F2 di zebrafish allo stadio di 1 cellula. In 2 linee stabili su 8, l’espressione telencefalo-specifica di GFP era ridotta a precoci stadi di sviluppo.
Abbiamo anche clonato alcuni DREs in vettori luciferasi per esperimenti di transfezione in colture cellulari. Uno dei DREs mostrava un aumento di attività luciferasica in cotransfezione con vettori di espressione per Sox2 e Mash1, suggerendo un meccanismo di regolazione in cui SOX2 opera insieme al cofattore MASH1.
Possiamo concludere che alcuni DREs testati, selezionati tra le interazioni “long-range” di ChIA-PET perse nelle NPCs Sox2-delete, agiscono come elementi regolatori in esperimenti in vivo e sono direttamente regolati da SOX2.Sox2 encodes a transcription factor required for embryonic stem cell pluripotency. Heterozygous Sox2 mutations in humans cause defects in the development of eyes (anophthalmia, microphthalmia) and hippocampus, with neurological pathology including epilepsy, motor control problems and learning disabilities. Using a Sox2 conditional knock-out in mouse, we discovered that Sox2 is important for brain development and for neural stem cell maintenance. Recently, it was found that transcriptional regulatory elements are not always localized in proximity of the gene they control, but often they lie very far from it on the linear chromosome map. Mutations in these elements can cause pathology, due to the deregulation of the associated gene. In collaboration with Dr. C.-L. Wei’s lab (California), we compared long-range DNA interactions in chromatin of wild-type mouse neural stem/precursor cells (NPCs) and Sox2-deleted cells, using the ChIA-PET technique: out of a total of 7000 long-range interactions mapped in wild-type NPCs, 2700 were lost in Sox2-deleted cells. Many of the lost interactions involved genes important for neural development and sequences already identified as forebrain enhancers by p300 binding in mouse developing telencephalon. In parallel, we determined the genome-wide map of SOX2 binding sites in chromatin of wild-type NPCs, by ChIP-seq (in collaboration with Dr. F. Guillemot; London). At least half of the SOX2-dependent long-range interactions contain a SOX2 ChIP-seq peak, suggesting that SOX2 has a direct role in their maintenance. My project seeks to define if distal sequences, associated in a SOX2-dependent way to neural genes (candidates to be putative SOX2 targets), represent transcriptional regulatory elements active during embryonic brain development and if their activity is regulated by SOX2. We selected 13 putative distal regulatory elements (DREs), among the ChIA-PET interactions lost in Sox2-deleted cells, to functionally characterize them in transgenic experiments in zebrafish. I did the transgenesis experiments in Dr. P. Bovolenta’s lab in Madrid, supported by an EMBO short-term fellowship. We cloned the 13 DREs upstream of a minimal promoter and a GFP gene (in a “ZED” plasmid). The plasmid is injected in 1-cell stage embryos and the DNA is integrated into the fish genome. After injection, the embryos are observed during development to analyze if, and where, the tested sequences drive GFP expression. I found that 12 out of 13 DREs give rise to reproducible GFP expression in the developing forebrain and/or in more posterior neural regions, matching the expression pattern of the associated gene. This indicates that the selected DREs alone are able to guide reporter gene expression. I collected the transient GFP+ embryos (F0) of 8 DREs to obtain F1 stable transgenic lines. To test if the enhancer activity of DREs is regulated by SOX2, I used a loss of function experiment. I injected a morpholino antisense oligonucleotide, specifically directed against the Sox2 mRNA, in F2 zebrafish embryos at 1-cell stage. Two, out of 8, stable lines showed a reduced GFP expression specifically in forebrain in early developmental stages. We have also cloned some of the selected DREs in a luciferase vector to test them by transfection in cultured cells. One of the DREs showed a significant increase in luciferase activity if co-transfected with Sox2 and Mash1 expressing vectors, suggesting a regulatory mechanism operated by SOX2 on this element in presence of the cofactor MASH1. We can conclude that some of the tested DREs, involved in ChIA-PET interactions lost in Sox2-deleted cells, work as regulatory elements in in vivo experiments and are directly regulated by SOX2.
9
Hütz, Katharina Antonia [Verfasser], et Thomas [Akademischer Betreuer] Cremer. « The role of the transcription factor SOX2 in tumorigenesis and development of the stomach / Katharina Antonia Hütz. Betreuer : Thomas Cremer ». München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/106031858X/34.
Texte intégral
10
Zayed, Hebatalla [Verfasser], Iver [Gutachter] Petersen, Peter [Gutachter] Elsner et Alexander [Gutachter] Marx. « Stem cell transcription factor SOX2 in synovial sarcoma and other soft tissue tumors / Hebatalla Zayed ; Gutachter : Iver Petersen, Peter Elsner, Alexander Marx ». Jena : Friedrich-Schiller-Universität Jena, 2019. http://d-nb.info/120588419X/34.
Texte intégral
11
Lee, Yiu-fai Angus. « Tissue-specific transcriptional regulation of Sox2 ». Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B3955739X.
Texte intégral
12
Lee, Yiu-fai Angus, et 李耀輝. « Tissue-specific transcriptional regulation of Sox2 ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B3955739X.
Texte intégral
13
Li, Junchang, et 李俊畅. « Sox2 and inner ear development ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hdl.handle.net/10722/206990.
Texte intégralRésumé :
Sox2, a HMG box transcription factor, is well known for its role in stem cell maintenance, iPS (induced pluripotent stem cell) induction, and development of neural tissues such as central nervous system and sensory organs. Sox2 has been demonstrated to be essential for the development of inner ear sensory patches. It has been shown that Sox2 is under the regulation of multiple regulatory elements to obtain a tissue specific manner.
Two allelic mouse mutants, yellow submarine (Ysb) and Light coat and circling (Lcc) show hearing and balance impairments with different severity. They were made by random insertions of a transgene (pAA2) and X-ray irradiation respectively. Ysb and Lcc are both localized to chromosome 3 and involve complex chromosomal rearrangements. The Sox2 coding region is intact in the mutants, while the Sox2 expression in the otocyst is greatly reduced in Ysb and totally lost in Lcc, which indicates the tissue specific reduction of Sox2 may be due to the rearrangement of Sox2 regulatory element(s). Since Sox2 null mutants die before implantation, the two Sox2 inner ear mutants are valuable models for studying Sox2 knock down (Ysb) and Sox2 knock out (Lcc) condition in the inner ear. To understand the molecular basis behind Sox2 regulation in the inner ear, this project aims to identify the Sox2 otic regulatory elements, and potential Sox2 downstream targets involved in the development of inner ear.
Previous work has indicated that Nop1 and Nop2 are the otic specific regulatory elements of Sox2 in chicken ear. In this project, transgenic mice were generated using Nop1-Nop2, and the result showed Nop1-Nop2 could drive Sox2 expression to the dorsal side of the otiv vesicle, which is different from the endogenous Sox2 expression pattern. Therefore, Nop1 and Nop2 may require other regulatory element(s) to gain a correct regulatory pattern. BAC(RP23-335P23), which contained the DNA sequences close to Ysb integration site 1 was also been tested in transgenic mice. Interestingly, the result showed that BAC(RP23-335P23) could drive Sox2 expression to the ventral side of the otic vesicle, indicating that this BAC may contain the Sox2 otic regulatory element(s).
In this project, the binding relationship between Sox2 protein and Math1 enhancer has also been identified using chromatin immunoprecipitation (Ch-IP). Results showed that Sox2 could bind to Math1 enhancer A in the inner ear cochlea. So Sox2 may regulate Math1 through binding to Math1 enhancer A in inner ear development.
Using a bioinformatics approach, potential Sox2 target genes in inner ear development have been identified from public microarray data on E9 to E15 inner ear tissue by the presence of conserved Sox2 binding sites. Among these potential targets, 4 genes (Itga6, Erbb3, Sox10 and Mycn) have been selected based on their known functions. Their expression patterns in the cochlea of wild type, Ysb and Lcc were verified. The identification of Sox2 downstream target genes using a bioinformatics approach will help us to understand the molecular basis of Sox2 regulation, and also understand the role of Sox2 in the inner ear development.published_or_final_version
Biochemistry
Master
Master of Philosophy
14
Chan, N. S. Michelle. « The roles of Sox2 and Sox18 in hair type specification and pigmentation ». View the Table of Contents & ; Abstract, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38024974.
Texte intégral
15
Sites, Emily. « Proposed Roles for Sox Transcription Factors and Growth Factor Receptors in NF1 ». University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1226071241.
Texte intégral
16
Chan, N. S. Michelle, et 陳雁璇. « The roles of Sox2 and Sox18 in hair type specification and pigmentation ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38905292.
Texte intégral
17
Ho, Siu-yin Bryan, et 何兆賢. « Genetic analyses of the roles of Sox2 and Sox18 in mouse hair development and growth ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206748.
Texte intégralRésumé :
The mouse pelage hair consists of three types of hair coined primary (guard), secondary (awls and auchenes) and tertiary (zigzag) hair. They display distinct morphologies and are induced consecutively during hair morphogenesis. Previously two identified regulatory mouse mutants, Yellow submarine (Ysb) and Light coat and circling (Lcc) which the chromosomal rearrangements have disrupted the cis-acting regulatory elements of Sox2; resulting in the loss of Sox2 expression in the inner ear. The mutants displayed lighter hair coat color due to a reduction in the proportion of secondary hair and increased proportion of tertiary hair. Sox18 null mutants display darker coat colour and reduced proportion of zigzag hair. To dissect the underlying mechanisms of the phenotypes in hair type specification in 〖Sox2〗^Ysb and 〖Sox2 〗^Lcc mutants and the role of Sox2 and Sox18 in regulating the process; the expression of Sox2 in the hair follicle and the change in the density of hair types in mutants were analyzed.
I have identified the expression pattern of Sox2 in the dermal papilla (DP) of the hair follicle and verified its down-regulation in 〖Sox2〗^Ysband 〖Sox2 〗^Lcc mutants. The DP at the base of hair follicle is the signaling center for the regulation of hair development. Sox2 is specifically expressed in the DP of primary and secondary but not in tertiary hair while Sox18 is expressed in the DP of all hair types. Analysis of Sox2 mutants showed that the number of secondary hair was normal at induction but was reduced and accompanied by an increase in tertiary hair in adult mice. The number of tertiary hair was reduced in Sox18 null mutants. To gain insight into the molecular basis of hair type specification and potential targets of Sox2 in the regulation, gene expression profile in DP cells of 〖Sox2 〗^(EGFP/+)and 〖Sox2 〗^(EGFP/Ysb) mice was examined; the data suggests that genes in the Wnt and BMP signalling pathway were down-regulated in Sox2 mutants; while Runx3 and Corin may act downstream of Sox2 in regulating hair type specification and pigmentation.
Hair follicles enter cycles of growth and regression throughout life during the hair cycle. Sox2 was only expressed in the growth phase while Sox18 was persistently expressed throughout the hair cycle. I further asked if Sox2 and Sox18 regulate post-natal hair development by analysing the expression pattern of Sox2 and Sox18 in wildtype mice and mutants throughout the hair cycle and the progression of hair growth in the mutants. The growth phase of the first hair cycle was extended in Sox2 mutants while the hair cycle in Sox18 null mutants was normal. Cell proliferation was compromised during hair regeneration leading to a delay in hair regeneration in Sox2 mutants.
Sox2 and Sox18 showed overlapping expression in the DP and both regulate hair type specification. To test if Sox2 and Sox18 synergistically regulate hair development, the 〖Sox2〗^(Ysb/Ysb);〖Sox18〗^(-/-) mutants have been generated. Hair morphogenesis and differentiation were impaired; while the number of tertiary hair was increased with reduced number of secondary hair, which phenocopied that of Sox2 mutants. In conclusion, the results suggest that Sox2 and Sox18 functions synergistically on the regulation of hair growth and differentiation.published_or_final_version
Biochemistry
Doctoral
Doctor of Philosophy
18
Jafarnejad, Shourkaei Seyed Mehdi. « Role of Sox4 transcription factor in human cutaneous melanoma ». Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/44026.
Texte intégralRésumé :
Cutanous melanoma is an aggressive malignancy with very few effective treatment strategies in
the early stages and virtually no successful cure in the late stages. So far many aspects of biology
of melanoma, especially mechanisms responsible for its metastasis have remained undiscovered.
The SRY-related HMG box4 (Sox4) protein is aberrantly expressed in several types of tumors.
In this study we investigated the role of Sox4 in human cutaneous melanoma. We hypothesized
that expression of this protein is changed during melanoma progression with functional
consequences on progression of melanoma. We revealed that Sox4 expression is reduced in
metastatic melanomas and this loss of expression correlates with poorer patients survival. We
found that Sox4 expression is required for suppression of melanoma cell migration and invasion.
We determined that Sox4 uses at least two distinct pathways to suppresses melanoma cell
migration and invasion. First, through binding to the regulatory regions and inhibiting the
transcription of NF-κB p50. Secondly, it also regulates the miRNA biogenesis pathway at least
partially through upregulation of the pre-miRNA processor, Dicer. Moreover, we showed that
expression of Sox4 inversely correlates with that of NF-κB p50 in melanoma biopsies but
positively correlates with Dicer expression which further supports our in vitro observations. We
also revealed that expression of Dicer, similar to its upstream regulator Sox4, decreases in
metastatic melanoma and this reduced expression inversely correlates with patient survival. In
addition to Dicer, we also found that expression of the pre-miRNA processing enzyme Drosha is
reduced in early stages of melanomagenesis. Dicer and Drosha demonstrate different expression
patterns which imply differential regulatory mechanisms. Nevertheless, samples that lost
expression of both Dicer and Drosha represented worse survival outcome in contrast to those with positive expression of both markers. Finally, we revealed that the subcellular localization of
Dicer and Drosha may be deregulated in melanocytic lesions and possibly has relevance to the
biology of melanoma.
The data presented in this thesis elucidated a hitherto unknown mechanism responsible for
suppression of metastasis which is malfunctioned in melanoma. A better understanding of this
pathway may help toward treatment or prevention of metastatic melanoma.
19
Sandberg, Magnus. « Sox proteins and neurogenesis ». Stockholm, 2010. http://diss.kib.ki.se/2010/978-91-7409-873-0/.
Texte intégral
20
Kwok, Sin-ting Cindy, et 郭倩婷. « The role of SoxE transcription factors in melanoma development ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47251074.
Texte intégralRésumé :
Melanoma is a malignant type of skin cancer arising from the combined effects of genetic alteration and extrinsic signaling, resulting in transformation of neural crest (NC)-derived melanocytes into metastatic melanoma. Current therapies against metastatic melanoma are merely effective with less than 5% 5-year survival rate of patients. Understanding the underlying molecular mechanism of how melanoma acquires metastatic behavior could formulate strategies for new therapeutic options. Features of metastatic melanoma resemble NC cells undergoing an epithelial-mesenchymal transition (EMT) suggesting similar regulators might be in place to control the process. Our previous studies showed that SoxE transcription factors (Sox8/9/10) play a crucial role in NC development, in particular Sox9 transactivates expression of Snail2 and co-operates with it to induce features of EMT.
To examine the role of SOXE proteins in melanoma development and whether they regulate SNAIL expression, we first investigated the expression profile of SOXE and SNAIL in a human melanoma tissue array. The data showed that SOX8, SOX10, and SNAIL genes are highly expressed in metastatic melanoma whereas SOX9 and SNAIL2 transcript levels are low. Moreover, SNAIL transcript level was shown to have a positive correlation with SOX8 and SOX10 expression levels. SNAIL is well-known to be the key regulator of tumor invasiveness in various cancers. Our data raised the possibility that SOXE proteins may also regulate SNAIL expression in initiating melanoma metastatic behavior. The human metastatic melanoma cell line A375 exhibits similar SOXE and SNAIL expression profiles as the tissue array. Knockdown of SNAIL in A375 reduced its migratory ability and in vivo tumorigenecity, suggesting that SNAIL plays a crucial role in melanoma metastasis.
How SNAIL transcription is regulated in melanoma has been poorly understood. Previous studies have identified a minimal enhancer region downstream of the SNAIL locus which contains YY1 and SOX consensus binding sequences. Chromatin immunoprecipitation assay revealed that SOX8 and SOX10 proteins could bind to the SNAIL 3’ minimal enhancer region specifically. Mutation of the SOX consensus binding sequence reduced the enhancer activity while mutations in both SOX and YY1 binding sites resulted in further reduction suggesting that YY1 and SOX protein binding is required and important for enhancer activity and SNAIL transcription. These findings provide a molecular basis to examine further whether metastasis of melanoma is regulated by SOXE proteins in which one of the potential mechanisms could act through regulation of SNAIL expression.published_or_final_version
Biochemistry
Master
Master of Philosophy
21
Tai, C. P. Andrew. « An in vivo analysis of specificity of gene transactivation by SOX proteins ». Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36906438.
Texte intégral
22
Tai, C. P. Andrew, et 戴賜鵬. « An in vivo analysis of specificity of gene transactivation by SOX proteins ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B36906438.
Texte intégral
23
Garside, Victoria C. « Analysis of transcriptional targets of SOX9 during embryonic heart valve development reveals a critical network of transcription factors ». Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55600.
Texte intégralRésumé :
Cardiac malformations affect approximately 1% of human newborns and a large number of these are due to defects in the heart valves and septum. It has been suggested that cardiac valve diseases, which make up about one third of all cardiovascular defects, arise from underlying developmental malformations that occur during embryogenesis. Interestingly, the development of the heart valves (cardiac cushions) and tissues that form cartilage templates (such as the limb) share a number of key TFs, such as TWIST1, SOX9, and NFATC1 suggesting that they have similar transcriptional programs. It has been proposed that regulatory networks involved in cartilage formation, are also active during valve development and disease. The transcription factor SOX9 has an essential role in heart valve and cartilage formation and its loss leads to major congenital abnormalities in the embryo. Regardless of this critical role, little is known about how SOX9 regulates heart valve development or its transcriptional targets. Therefore, to identify transcriptional targets of SOX9 and elucidate the role of SOX9 in the developing valves, we have used ChIP-Seq on the E12.5 atrioventricular canal (heart valves) and limb buds. Comparisons of SOX9DNA-binding regions among tissues revealed both context-dependent and context–independent SOX9 interacting regions. Context-independent SOX9 binding suggests that SOX9 may play a role in regulating proliferation-associated genes across many tissues. Generation of two endothelial specific Sox9 mutants uncovers two potential roles for SOX9 in heart valve formation: first in the initial formation of valve mesenchyme and later in the survival and differentiation of valve mesenchyme. Analysis of tissue-specific SOX9-DNA binding regions with gene expression profiles from Sox9 mutant heart valves indicates that SOX9 directly regulates a collection of transcription factors known to be important for heart development. Taken together, this study identified that SOX9 controls transcriptional hierarchies involved in proliferation across tissues and heart valve differentiation. SOX9 transcriptional targets identified in this data could be used as predictive factors of heart valve disease, or as targets for new therapeutic strategies for disease and congenital defects.Medicine, Faculty of
Graduate
24
Chui, Tung-yung, et 崔董庸. « The role of ALDH and SOX2 as tumour initiating cell markers in non-small cell lung cancer ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/193557.
Texte intégralRésumé :
The abundance of tumour initiating cells (TIC) has been suggested to be an important prognostic indicator in cancers. Both SOX2 and ALDH have been individually reported to be putative TIC markers but their combined status is unclear and their usefulness in the prognostication of non-small cell lung cancer (NSCLC)has not been reported. This study investigated the patterns of ALDH and SOX2 protein expression in NSCLC using immunohistochemistry. Expression was graded using semi-automated signal capturing and image analysis software. ALDH and SOX2 were expressed in 41% and 43% of all NSCLC, respectively. ALDH was expressed in 36% of adenocarcinomas (AD)and 65% of squamous cell carcinomas (SCC), while SOX2 was expressed in 36% of AD and 80% of SCC., respectively. Taking all cases into consideration, the expression of ALDH and SOX2 significantly correlated with each other (p=0.003). No prognostic value of the abundance of ALDH and SOX2-expressing cancer cells was found with regard to all NSCLC or in AD. In contrast, for SCC, a significantly better prognosis with longer cancer-specific survival (CSS) and disease-free survival was found in tumours with higher ALDH expression, while a longer CSS was found in those with higher SOX2 expression. Contrary to the hypothesis that a high TIC content indicated by high combined ALDH and SOX2 expression would predict poor patient outcome, amongst all NSCLC, the combined phenotype of SOX2+/ALDH-was associated with the worst prognosis compared with the SOX2+/ALDH+(p=0.026) and SOX-/ALDH-(p=0.048),while no significant difference was observed with the SOX-/ALDH+ phenotypes. In view of the tight correlation between ALDH and SOX2 protein levels, in vitro studies were performed to investigate whether ALDH could be an upstream regulator of SOX2 expression. Pharmacological inhibition of ALDH enzyme function led to down-regulation of SOX2 mRNA and nuclear protein expression in lung cancer cell lines, indicating a regulatory role of ALDH on the SOX2 stemness pathway in lung cancer. In summary, the findings implicate complex factors are likely to be involved in determining the expression levels of ALDH and SOX2 in clinical lung cancers and their mechanisms affecting patient survival remain to be clarified. Further investigations on the specificity of ALDH/SOX2 as TIC marker, TIC interaction with the tumour micro-environment, and potential complex antagonistic functions of ALDH in TIC maintenance are required.published_or_final_version
Pathology
Master
Master of Medical Sciences
25
Putwain, Sarah Lucy. « The role of Sox4 in acute myeloid leukaemia ». Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648624.
Texte intégral
26
Hui, Man-ning, et 許文寧. « Investigating the role of SOX9 in human neural stem cells ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/193481.
Texte intégralRésumé :
Neural stem cells (NSCs) exist in both embryonic and adult neural tissues and are characterized by their self-renewal capacity and multipotency that contribute to the generation of three major cell types in the vertebrate central nervous system (CNS):neurons, oligodendrocytes and astrocytes. The tremendous therapeutic potential of NSCs to treat the neurodegenerative diseases and repair brain injuries has provoked intensive study in the molecular regulation of their induction, maintenance and differentiation.
Previous study reported that Sox9, a member of high-mobility-group(HMG) containing SoxE transcription factors family, plays important roles in regulating the formation and maintenance of NSCs in both mouse and chick CNS, as well as the cell fate switch between neuronal and glial. Whether it plays similar roles in human NSCs (hNSCs)is still unknown. My RT-qPCR analysis showed that SOX9is expressed at a basal level in human embryonic stem cells (hESCs) and up-regulated upon commitment into neural lineage and maintained at a high level in hESCs-derived hNSCs. I therefore hypothesized that SOX9 might also be involved in the induction, maintenance and differentiation of hNSCs.
To test this, two stable hESC lines(HES2)were generated with each constitutively expressing short hairpin RNA (shRNA) against SOX9andGL2 Luciferase (Luc, as control) respectively. Upon neural induction, SOX9-knock-down(KD) hESCs were able to commit neural lineage and differentiate into NSCs/neurospheres (NSPs), however, these NSCs exhibited reduced multipotency and glial marker (GALC, CD44) expressions but enhanced self-renewal compared to the shLuc NSCs. Hence, SOX9 is required for both the induction and maintenance of multipotent hNSCs. Strikingly, extensive TUJ1+ neurites and advance groupings of these neurites into bundles were observed in SOX9-KD NSPs after three days and seven days neuronal differentiation respectively, suggesting premature neurogenesis as a result of SOX9 ablation.
In addition, RT-qPCR analysis revealed down-regulated expression of NSC marker HES1but induced proneural basic helix-loop-helix transcription factor MASH1in shSOX9-1208 NSCs. The inhibitory role of HES1 on the expression and functions of MASH1 has been reported to be essential for the timely generation of neurons. Hence, ablation of SOX9 is likely to relieve the inhibition on MASH1activity via down-regulated HES1expression and leads to early neuronal differentiation. Expression of the potent neurite blocker NG2 was also found to be reduced in SOX9-KD NSCs which may explain the extensive neurite network observed. Altogether, similar to previous studies in mouse NSCs, SOX9 is also required for the induction and maintenance of hNSCs. However, this study further reveals a putative novel role of SOX9 in preventing premature neuronal differentiation by regulating the expressions of HES1 to counteract MASH1 function and NG2 to control neurite outgrowth.published_or_final_version
Biochemistry
Master
Master of Philosophy
27
Julian, Lisa. « Regulation of Neural Precursor Cell Fate by the E2f3a and E2f3b Transcription Factors ». Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/25489.
Texte intégralRésumé :
The classical cell cycle regulatory pathway is well appreciated as a key regulator of cell fate determination during neurogenesis; however, the extent of pRB/E2F function in neural stem and progenitor cells is not fully understood, and insight into the mechanisms underlying its connection with cell fate regulation are lacking. The E2F3 transcription factor has emerged as an important regulator of neural precursor cell (NPC) proliferation in the embryonic and adult forebrain, and we demonstrate here that it also influences the self-renewal potential of NPCs. Using knockout mouse models of individual E2F3 isoforms, we demonstrate the surprising result that the classical transcriptional activator E2F3a represses NPC self-renewal and promotes neuronal differentiation, while E2F3b promotes the expansion of the NPC pool and inhibits differentiation. We attribute these opposing activities to a unique mechanism of transcriptional regulation at the Sox2 locus, a key regulator of stem cell pluripotency, whereby E2F3a recruits transcriptional repressors to this site, and E2F3b promotes Sox2 activation. Importantly, E2F3a-mediated Sox2 regulation is necessary for cognitive function in the adult. Additionally, through the determination of genome-wide promoter binding sites for E2f3 isoforms as well as E2F4, another key regulator of NPC self-renewal, we determined that E2Fs are poised to regulate an extensive set of target genes with key roles in regulating diverse cell fate choices in NPCs, including self-renewal, cell death, progenitor expansion, maintenance of the precursor state, and differentiation. Together, these results reveal a diversity of function for E2Fs in the control of neural precursor cell fate, and identify E2F3 isoforms as important regulators of the pluripotency and stem cell maintenance gene Sox2.
28
Geng, Yuhong, et 耿雨紅. « Functional studies of SOX9 in mouse development ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31243071.
Texte intégral
29
Peacock, Jacqueline D. « The Role of Sox9 in Heart Valve Development and Disease ». Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/543.
Texte intégralRésumé :
Heart valve structures open and close during the cardiac cycle to provide unidirectional blood flow through the heart, critical for efficient cardiovascular function. Valve dysfunction results in either incomplete opening or incomplete closure of the valve. Both types of valve dysfunction decrease efficiency of blood flow, increasing the load on the myocardium and leading to secondary heart disease such as pathological hypertrophy and heart failure. There are currently no effective treatments to prevent or slow the progression of valve disease, and there are no pharmacological treatments for advanced valve disease. Although most valve disease is associated with aging, increasing evidence suggests that valve disease often has origins in development. Congenital valvuloseptal defects affect many newborns, ranging from life-threatening malformations requiring immediate repair to more subtle, often undiagnosed defects that increase susceptibility to valve disease later in life. Therefore, an improved understanding of the mechanisms of heart valve formation and maintenance of adult valves may serve as an important step in improving valve disease treatment options. In this work, the mechanisms of normal valve development and the role of Sox9 in developing and mature valves are further studied. The temporal and spatial expression of extracellular matrix genes and proteins are examined throughout normal murine valve development. Sox9 function in the processes of valve development and valve maintenance is examined using mouse models of conditional Sox9 loss-of-function. Heart valve phenotypes in mice with reduced Sox9 function are examined throughout development and in adult mice with resultant calcific valve disease. The possible causative mechanisms of calcific valve disease in mice with reduced Sox9 function are further investigated by identification of novel possible targets of Sox9 transcriptional regulation. Together these studies improve our understanding of heart valve development, characterize a model of heart valve calcification with genetic etiology, and identify and characterize novel targets of Sox9.
30
Mak, Chi-yan Angel, et 麥志昕. « Bioinformatic and functional approaches to identify potential SOX9 target genes in inner ear development ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hdl.handle.net/10722/193405.
Texte intégral
31
FONT, MONCLUS ISAURA. « Identification and characterization of protein complexes including the transcription factor Sox6 in erythroid cells ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/83998.
Texte intégralRésumé :
β hemoglobiniopathies (Sickle cell Anemia (SCA) and β-thalassemias) are genetic diseases caused by mutations in the β-globin gene, resulting in a defective production of the adult hemoglobin (HbA; α2β2) tetramer. Coinheritance of hereditary persistence of fetal hemoglobin (HbF α2γ2) expression greatly ameliorates the clinical symptoms in these patients.
Thus, understanding the molecular mechanisms underlying the γ to β switch is important to design strategies for the pharmacological up-regulation of γ globin. Sox6 is a Transcription Factor with a crucial role in terminal erythroid maturation and in the hemoglobin fetal/adult switching. Sox6 can act both as transcriptional activator or repressor, but it lacks any conventional activator or repression domain, suggesting that Sox6 has to interact with other proteins or complexes to exert its function.
To draw a map of Sox6 interactors in erythroid cells, we undertook the purification of Sox6 complexes by using a biotynilation-tagging approach followed by Mass-Spectrometry in human erythroleukemic HEL cells. Sox6 was found to interact with multiprotein complexes consisting of chromatin remodeling factors, transcriptional corepressors, cyclines dependent kinases (CDKs) and erythroid transcription factors. In particular, Sox6 interacts with most of the subunits of the chromatin-remodeling co-repression NurD (Nucleosome Remodeling Deacetylase) complex. The knockdown of some of these interactors by siRNA transfection in erythroid cells confirms a crucial role of Sox6 complexes in erythroid differentiation and globin genes regulation.
32
Nguyen, Julie. « Rôle du facteur de transcription Sox9 dans l'homéostasie et la tumorigenèse intestinales ». Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTT046.
Texte intégralRésumé :
Le maintien de l’homéostasie intestinale met en jeu un dialogue entre l’épithélium, le microbiote et le système immunitaire. Les CSI assurent le renouvellement et la régénération de l’intestin en cas de lésions mais elles peuvent être également à l’origine des tumeurs intestinales. Le facteur de transcription Sox9 est un candidat intéressant comme régulateur clé de l’homéostasie intestinale car il est exprimé dans les CSI, les cellules de Paneth et les cellules tuft. De plus, Sox9 est indispensable à la différenciation des cellules de Paneth puisque l’inactivation de Sox9 chez l’embryon (modèle murin Sox9LoxP/LoxP ; Villin-Cre) conduit à une absence de cellules de Paneth. Au cours de ma thèse, nous avons dans un premier temps déterminé la fonction de Sox9 dans l’épithélium intestinal adulte à l’aide du modèle murin inductible : Sox9LoxP/LoxP ; Villin-CreERT2. Ainsi nous avons démontré que la délétion de Sox9 dans les cellules de Paneth conduit à des altérations structurales et fonctionnelles de ces dernières, qui induisent une altération de la biodiversité d’espèces bactériennes (dysbiose). La dysbiose est « sentie » par les cellules tuft qui initient une réponse immunitaire de type 2. Cette étude a révélé le rôle clé de Sox9 dans les cellules de Paneth adultes pour réguler l’homéostasie intestinale, en prévenant l’établissement d’un microbiote pro-inflammatoire. Les cellules tuft, via leur fonction de « sensing », sont capables en réponse à une dysbiose de moduler l’immunité mucosale et participent ainsi à la formation d’un cercle vicieux délétère. De plus, nous nous sommes intéressés à la biologie des CSI, en intégrant la contribution des propriétés des cellules de Paneth qui participent à l’établissement de la niche. Nous avons étudié les propriétés des cellules souches dans un contexte sain ou au cours de l’initiation tumorale. L’ensemble de nos données indiquent qu’en contexte sain, Sox9 est requis pour la régulation du destin cellulaire des CSI, c’est à dire l’équilibre entre l’auto-renouvellement des CSI et leur différenciation cellulaire. Les mécanismes régulés par Sox9 mettent en jeu le métabolisme cellulaire, un acteur clé du destin des cellules souches. Nos travaux montrent également que le maintien d’une niche intacte est nécessaire au contrôle du devenir des CSI. La délétion de Sox9 altère l’intégrité mitochondriale et favorise la production de ROS mitochondriaux qui pourrait moduler le destin des CSI vers un état différencié. En parallèle, nous avons mis en évidence que l’invalidation de Sox9 après l’acquisition d’un événement initiateur tel que la perte de fonction du gène suppresseur de tumeur Apc, affecte de façon majeure le destin des CSC vers un état souche ainsi que leur métabolisme cellulaire. L’évaluation du rôle du facteur de transcription Sox9 dans le contrôle de l’homéostasie métabolique permettra de mieux comprendre les mécanismes de régulation de la biologie des CSI, et de proposer à terme de nouvelles stratégies thérapeutiques ciblant les CSCThe intestinal homeostasis maintenance involves a permanent crosstalk between the epithelium, the microbiota and the immune system. ISC are responsible for the intestine renewal and regeneration, but they can also cause intestinal tumors. The Sox9 transcription factor is an interesting candidate as a key regulator of intestinal homeostasis because of its specific expression in ISC, Paneth cells and tuft cells. In addition, Sox9 is essential for the differentiation of Paneth cells since the loss of Sox9 in the mouse embryo (model Sox9LoxP / LoxP, Villin-Cre) leads to the absence of Paneth cells. First, we analysed the function of Sox9 in the adult intestinal epithelium using the inducible mouse model: Sox9LoxP / LoxP; Villin-CreERT2. We demonstrated that the deletion of Sox9 in adult Paneth cells leads to structural and functional alterations of Paneth cells, which induce alterations of bacterial diversity (dysbiosis). Dysbiosis is "sensed" by tuft cells that initiate a type 2 immune response. This study revealed the key role of Sox9 in adult Paneth cells to regulate intestinal homeostasis, thus preventing the establishment of a proinflammatory microbiota. Tuft cells, via their sensing function, are able to modulate mucosal immunity in response to a dysbiosis and thus participate in the formation of a vicious circle. In addition, we studied the biology of ISC, by integrating the contribution of Paneth cells properties that participate in the establishment of the niche. We analysed the properties of stem cells in a healthy context or during tumor initiation. Our data indicate that in a healthy context, Sox9 is required for the regulation of ISC fate, namely the balance between ISC self-renewal and differentiation. The mechanisms regulated by Sox9 involve cellular metabolism, a key player in the stem cells fate. Our work shows that an intact niche maintenance is necessary to control ISC fate. The deletion of Sox9 alters mitochondrial integrity and promotes mitochondrial ROS production that could modulate the ISC fate toward a differentiated state. In parallel, we demonstrated that Sox9 deletion concomitant with the acquisition of an initiating event such as the loss of function of the tumor suppressor gene Apc, affects the CSC and their cellular metabolism. The evaluation of the role of the Sox9 transcription factor in the control of metabolic homeostasis will provide a better understanding of the regulatory mechanisms in ISC biology, and eventually new therapeutic strategies targeting CSC might be proposed
33
Erickson, Drew Talyn. « Multiple Roles for the Transcription Factors Sox6 and Jumonji in Mouse Hematopoiesis ». Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195728.
Texte intégralRésumé :
Sox6, a member of the Sox transcription factor family, is essential for the silencing of epsilon-y-globin gene expression in definitive erythropoiesis of mice and humans. Homozygous Sox6 null mice are neonatal lethal, precluding analysis at later stages. We created adult mice that are deficient in Sox6 specifically in hematopoietic tissues, by transplanting embryonic liver stem cells from Sox6-deficient mice into lethally-irradiated congenic wild-type adult mice. The mice receiving mutant stem cells (mutant-engrafted) showed high expression levels of epsilon-y in bone marrow, spleen and circulating blood compared to mice receiving wild-type and heterozygous stem cells (control-engrafted). The level of expression of epsilon-y in circulating blood was directly correlated with the percentage of successful mutant donor cell engraftment. Additionally, the mutant-engrafted adult mice showed an increase in erythroid precursor cells in bone marrow, spleen and blood. Thus, Sox6 continues to function as a major regulator of epsilon-y in adult definitive erythropoiesis and is required for normal erythrocyte maturation. Moreover, Sox6 may provide a novel therapeutic target by reactivating epsilon-y in patients with hemoglobinopathies such as sickle cell anemia and beta-thalassemia.We have also identified another transcription factor, jumonji, as a downstream target of Sox6. Jumonji is a crtitical transcription factor in neural, cardiac and erythroid development. We report here that jumonji is over-expressed in the fetal liver of Sox6-deficient mice (p100H/p100H). Transfection assays in H2.35 cells reveal that a ~1.6-kb genomic fragment, including the 5' UTR of jumonji, contains both promoter activity and Sox6-mediated repression. Chromatin immunoprecipitation and electromobility shift assays demonstrate that Sox6 binds to a region within the second exon of jumonji. Further transfection analyses confirm that one of five putative binding sites for Sox6 in this region is required for the majority of Sox6-mediated transcriptional repression. In irradiated mice engrafted with Sox6-deficient hematopoietic stem cells, jumonji expression levels are significantly elevated in blood and bone marrow. These results demonstrate that Sox6 plays a major role in the direct repression of jumonji transcription, and it is likely that jumonji plays a cell-autonomous role in the subsequent hematopoietic cell phenotype seen in Sox6-deficient mice.
34
Menzel-Severing, Johannes [Verfasser], et Andreas [Gutachter] Feigenspan. « Transcription factor gene expression profiling and analysis of SOX gene family transcription factors in human limbal epithelial progenitor cells / Johannes Menzel-Severing ; Gutachter : Andreas Feigenspan ». Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1153203359/34.
Texte intégral
35
Boopathi, Ramachandran. « Structure de haute résolution du complexe nucleosome-H1 et son interaction avec le facteur de transcription Sox6 ». Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV020/document.
Texte intégralRésumé :
Comprendre la structure et l’organisation de la chromatine est une question fondamentale dans le domaine de la régulation de l’expression des gènes. La cristallographie par rayons-X et d’autres techniques biophysiques on permit de comprendre la structure du nucléosome avec une précision quasi atomique. Malgré de nombreuses études, les données structurelles au delà de la particule de cœur nucléosomale (NCP) demeurent imprécises. Au cours des dernières décennies plusieurs tentatives ont été faites pour montrer comment l’histone de liaison H1 interagit avec les particules nucléosomales pour les condenser en fibre de chromatine. Ces études ont mené à différents modèle décrivant la position de l’histone de liaison H1 sur la chromatine. De récentes avancées sur l’histone de liaison H1 suggèrent que le domaine globulaire de H1 (GH1) et la partie C-terminale interagit avec la dyade du nucléosome et les 2 bouts d’ADN de liaison (modèle à 3 contacts) qui sont contraintes de former une structure en tige. Cependant, la conformation et la position précise de l’histone de liaison H1 reste inconnues et la controverse à ce sujet persiste.Dans cette étude, nous avons déterminé la structure tridimensionnelle de nucléosomes contenant H1 par des techniques de cryo-microscopie électronique (cryo-EM) et de diffraction aux rayons-X dans des cristaux. Nous avons utilisé le chaperons d’histone, NAP1, pour déposer l’histone de liaison H1 sur les nucléosomes reconstitué à partir des histones de cœur recombinant et la séquence d’ADN positionnante 601 de 197 paires de bases (dite de Widom). Nos résultats de cryo-EM montrent que l’association de H1 compacte le nucléosome en réduisant la mobilité des ADNs et stabilisant ainsi les contacts entre les nucléotides précédant la sortie NCP et l’octamer d’histones. Nos résultats par diffusion de rayon-x dans des cristaux à une résolution de 7Ä montrent que la partie globulaire de H1 (GH1) est située sur la dyade et interagie simultanément avec les petits sillons de l’ADN à la dyade et les ADN de liaison à l’entrée et à la sortie du nucléosome. Les parties N- et C-terminales de H1 sont orientées vers l’extérieur du cœur du nucléosome à travers les différents ADN de liaison. Nous avons validé l’orientation de GH1 par des expériences de pontages ADN-proteine, après substitutions de cystéine par mutagénèse dirigée, empreinte par radicaux hydroxyles et « amarrage moléculaire ». Nos résultats révèlent l’effet de H1 sur la dynamique du nucléosome et apporte une vision détaillé de la conformation du « stem du nucléosome » lors de l’incorporation de H1.Nous avons également étudié l’association spécifique du facteur de transcription Sox6 à ces de reconnaissance consensus présent à l’intérieur du nucléosome, associé ou non avec l’histone de liaison H1 par une empreinte biphotonique avec laser UV. Nos résultats montrent que le domaine HMG de Sox6 se fixe spécifiquement sur son motif consensus situé profondément à l’intérieur du nucléosome à l’exception sur la dyade. Cette association n’est pas influencée par la « fermeture » des ADN de liaison avec l’histone H1 démontrant l’existence d’un autre façon de reconnaissance que le modèle de Widom basés sur fluctuations thermodynamiques des ADN de liaison. Le résultat que Sox6 est capable de surmonter la barrière nucléosomale (avec ou sans H1) suggère fortement que les facteurs de transcription de la famille Sox, de domaine de liaison de type HMG, jouent le rôle de facteurs « pionnier » dans la régulation de la transcription et en particulier dans l’initiation de la différentiationUnderstanding the structural organization of chromatin is a fundamental issue in the field of gene regulation. X-ray crystallography and other biophysical techniques have enabled understanding of the nucleosome structure nearly at atomic precision. Despite numerous studies, the structural information beyond the nucleosome core particle (NCP) remains elusive. Over the last few decades several attempts have been made to reveal how the linker histone H1 interacts with the nucleosome particles and condenses them into a chromatin fiber. These studies have led to different models describing the position of linker histone H1 on chromatin. Recent advancements in linker histone H1 studies suggest that globular domain of histone H1 (GH1) interacts with the nucleosomal dyad and its C-terminal domain interacts with the linker DNA forming a stem like structure. However, the precise conformation of linker histone H1 and position of other domains still remains unknown.In this study, we resolved the three-dimensional structure of H1-containing nucleosomes by using cryo-electron microscopy (cryo-EM) and X-ray crystallography. We have used the chaperone NAP-1 to deposit linker histone H1 onto nucleosomes reconstituted from recombinant core histones and 197 base-pair of 601 strong nucleosome positioning DNA sequence. Our cryo-EM results showed that association of H1 gives a more compact appearance of the nucleosome as it restricts the mobility of the two linker DNAs keeping them in close proximity and thereby stabilizing contacts between the histone core and nucleotides preceding NCP exit. Our X-ray crystallography results at 7 Ä resolution reveal that the globular domain of histone H1 (GH1) is positioned onto the nucleosome pseudodyad and recognizes the nucleosome core and both linker arms by contacting the DNA backbone in the minor groove. The N- and C-terminal domains of H1 are oriented away from the nucleosome core towards different DNA linkers. We further validated the orientation of GH1 by cross-linking experiments followed after cysteine substitutions mutagenesis, hydroxyl radical footprinting and by molecular docking. Our results reveal the effect of H1 on nucleosome dynamics and also provide a detailed view of the nucleosome stem conformation upon H1 incorporation.We also studyed the nucleosome accessibility of transcription factor Sox6 and the impact of linker histone H1 incorporation to Sox6 binding on nucleosome by using UV laser biphotonic footprinting. Our results reveal that Sox6 HMG domain binds specifically to its consensus binding located deep inside of the nucleosomal DNA, but not at the nucleosomal dyad. Our in vitro footprinting results reveal that the “locking” of DNA linkers by incorporation of histone H1 on nucleosome does not show any impact on Sox6 HMG domain binding, evidencing an alternative to the Widom model based on thermal fluctuation “opening” of the nucleosome at the linkers.. The finding that Sox6 is able to overcome nucleosome (chromatosome) barrier in presence or absence of H1, strongly suggest that the HMG domain - based Sox family proteins it can act as a pioneer factor in transcription regulation, in particular in initiation of cell differentiation
36
Fantinato, E. « ROLE OF THE TRANSCRIPTION FACTOR SOX9 IN THE TUMORIGENESIS OF SOME DOMESTIC ANIMALS NEOPLASMS ». Doctoral thesis, Università degli Studi di Milano, 2016. http://hdl.handle.net/2434/378481.
Texte intégralRésumé :
The first section of the thesis gives a brief overview of the literature about the transcriptor factor Sox9, focusing the attention on its main functions during developmental processes and in acquired deseases.
The second section, after a short introduction on Sox9 in Veterinary Medicine, is concerned with the assessment of Sox9 immunohistochemical staining in normal tissues of various animal species, in order to validate this marker in domestic animals.
The other sections present the findings of the research, with six original research studies concerning Sox9 immunohistochemical expression in several groups of neoplasms.
To better explain Sox9 role in nervous tissue development and in its neoplastic lesions they are treated together with Sox10 in the last work.
The table of contents is here reported:
The SOX family:
Sox9
Sox9 in tissues Sox9 in acquired diseases
SOX9 in veterinary medicine:
Sox9 in normal tissues of various animal species
SOX9 in the skin and hair follicle:
Sox9 in canine epithelial skin tumors
SOX9 in male gonad :
Immunohistochemical expression of Sox9 protein in immature, mature, and neoplastic canine Sertoli cells
SOX9 in mammary gland neoplasms:
Sox9 expression in feline mammary hypertrophy
Sox9 expression in feline mammary carcinomas
Sox9 expression in canine mammary neoplasms
Sox9 in nervous tissue and neoplasms:
Immunohistochemical panel evaluation for differential diagnosis of horse spindle cells tumors.
37
SERRA, LINDA. « Role of the Sox2 and COUP-TF1 transcription factors in the development of the visual system by conditional knock-out in mouse ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/261939.
Texte intégralRésumé :
Il fattore di trascrizione Sox2 è espresso nel sistema nervoso dall’inizio del suo sviluppo dove è richiesto per il mantenimento delle cellule staminali. Nell'uomo, le mutazioni eterozigoti di Sox2 sono collegate a vari difetti del sistema nervoso centrale, inclusi i difetti visivi. Il sistema visivo è composto dall'occhio, dal nucleo talamico genicolato dorsolaterale (dLGN) e dalla corteccia visiva, che sono altamente interconnessi. L'occhio, infatti, invia le afferenze retiniche ad uno specifico nucleo talamico dorsale, il dLGN, i cui neuroni a loro volta proiettano verso l'area corticale visiva. La corteccia visiva elabora input visivi e proietta al dLGN in un circuito complesso. Numerosi geni sono importanti per il corretto sviluppo del sistema visivo e Sox2 è uno di questi. Sox2 è espresso in tutti e tre i componenti del sistema visivo nel topo; mentre il suo ruolo nello sviluppo della retina è ben descritto si sa poco riguardo al suo ruolo nel talamo. Per studiare l’importanza di Sox2 nel talamo per il corretto sviluppo dell'asse visivo, abbiamo generato un knockout condizionale talamico di Sox2 nei neuroni post-mitotici. Abbiamo osservato che la perdita di Sox2 nel dLGN porta a una forte riduzione delle dimensioni del dLGN, all’alterazione delle proiezioni neuronali retino-talamiche, talamo-corticali e cortico-talamiche e, di conseguenza, a una difettiva definizione dell'area visiva corticale. Abbiamo scoperto che nei mutanti talamici di Sox2 il gene Efna5, importante nel guidare gli assoni retinici verso il dLGN, e i geni SERT e vMAT2 che codificano per trasportatori di serotonina, importanti per la corretta formazione di proiezioni talamo-corticali, sono fortemente sottoregolati nel dLGN mutante. Per identificare tutti i potenziali geni che potrebbero mediare la funzione di Sox2 nel talamo, abbiamo eseguito il sequenziamento dell'RNA (RNA-seq) su dLGN di controlli e mutanti di Sox2. Abbiamo scoperto che i geni deregolati sono arricchiti in geni che codificano per molecole importanti per la guida degli assoni e per molecole coinvolte nella neurotrasmissione e nelle sinapsi. È interessante notare che l'ablazione talamica di un altro fattore di trascrizione, COUP-TF1, porta a difetti del sistema visivo simili a quelli descritti per Sox2. Inoltre, le mutazioni eterozigoti nel gene COUP-TF1 nell'uomo portano all'atrofia ottica e a disabilità intellettive. Abbiamo scoperto che Sox2 e COUP-TF1 sono co-espressi negli stessi neuroni post-mitotici del dLGN. Sorprendentemente, l'espressione di COUP-TF1 non varia nei mutanti talamici di Sox2, facendo nascere la possibilità che Sox2 e COUP-TF abbiano target comuni nel talamo. Pertanto, abbiamo esaminato l'espressione, nei mutanti COUP-TF1, di geni sottoregolati nei mutanti talamici di Sox2 e sorprendentemente abbiamo scoperto che sembrano sovraregolati, suggerendo che i due fattori di trascrizione potrebbero agire sugli stessi geni ma in modo opposto. Per capire meglio se i due fattori di trascrizione regolano geni comuni, stiamo eseguendo l'analisi dell'espressione genica mediante RNA-seq anche sui mutanti talamici COUP-TF1. Inoltre, stiamo generando topi doppi mutanti per Sox2 e COUP-TF1 per scoprire come questi geni regolano espressione genica; è plausibile che regolino geni comuni per bilanciare la loro espressione nei neuroni talamici.The transcription factor Sox2 is expressed in the nervous system from the beginning of its development where it is required for stem cells maintenance. In humans, Sox2 heterozygous mutations are linked to various central nervous system defects, including visual defects. The visual system is composed of the eye, the dorsolateral geniculate thalamic nucleus (dLGN) and the visual cortex, which are highly interconnected. The eye, in fact, sends retinal afferent to a specific dorsal thalamic nucleus, the dLGN, whose neurons in turn project to the visual cortical area. The visual cortex elaborates visual inputs and projects back to the dLGN in a complex circuit. Several genes are important for the correct development of the visual system and Sox2 is one of them. Sox2 is expressed in all the three components of the visual system in mouse; while its role in the development of the retina is well characterized little is known about its role in the thalamus. To investigate Sox2 requirement in the thalamus for the correct establishment of the visual axis, we generated a thalamic Sox2 conditional knock-out in post-mitotic neurons. We observed that Sox2 loss in the dLGN leads to a strong reduction in size of the dLGN, aberrant retino-geniculate, thalamo-cortical and cortico-thalamic neural projections and, consequently, to a defective patterning of the cortical visual area. We found that in Sox2 thalamic mutants the Efna5 gene, important in guiding retinal axons towards the dLGN, and the serotonin transporters encoding genes SERT and vMAT2, involved in the establishment of thalamo-cortical projections, are strongly downregulated in the mutant dLGN. To identify all the potential genes that could mediate Sox2 function in the thalamus, we performed RNA sequencing (RNA-seq) on control and Sox2 mutant dLGNs. We noticed that misregulated genes are enriched in genes encoding axon guidance molecules and molecules involved in neurotransmission and synapses. Interestingly, thalamic ablation of another transcription factor, COUP-TF1, leads to defects of the visual system similar to the ones described for Sox2. In addition, heterozygous mutations in the COUP-TF1 gene in human lead to optic atrophy and intellectual disabilities. Interestingly, we found that Sox2 and COUP-TF1 are co-expressed in the same post-mitotic neurons of the dLGN. Surprisingly, COUP-TF1 expression does not vary in Sox2 thalamic mutants, arising the possibility that Sox2 and COUP-TF have common target in the thalamus. Therefore, we looked at the expression, in COUP-TF1 mutants, of genes downregulated in Sox2 thalamic mutants and we surprisingly found that they appear upregulated, suggesting that the two transcription factors could act on the same genes but in an opposite way. To better understand if the two transcription factors regulate common genes, we are performing gene expression analyses by RNA-seq also on COUP-TF1 thalamic mutants, with the aim to identify an overlap with Sox2 regulated genes. Moreover, we are generating Sox2 and COUP-TF1 double mutant mice to unveil how these genes regulate gene expression; it is plausible that they regulate common genes to balance their expression in thalamic neurons.
38
Carl, Sarah Hamilton. « Evolutionary patterns of group B Sox binding and function in Drosophila ». Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/247430.
Texte intégralRésumé :
Genome-wide binding and expression studies in Drosophila melanogaster have revealed widespread roles for Dichaete and SoxNeuro, two group B Sox proteins, during fly development. Although they have distinct target genes, these two transcription factors bind in very similar patterns across the genome and can partially compensate for each other's loss, both phenotypically and at the level of DNA binding. However, the inherent noise in genome-wide binding studies as well as the high affinity of transcription factors for DNA and the potential for non-specific binding makes it difficult to identify true functional binding events. Additionally, externalfactors such as chromatin accessibility are known to play a role in determining binding patterns in Drosophila. A comparative approach to transcription factor binding facilitates the use of evolutionary conservation to identify functional features of binding patterns. In order to discover highly conserved features of group B Sox binding, I performed DamID-seq for SoxNeuro and Dichaete in four species of Drosophila, D. melanogaster, D. simulans, D. yakuba and D. pseudoobscura. I also performed FAIRE-seq in D. pseudoobscura embryos to compare the chromatin accessibility landscape between two fly species and to examine the relationship between open chromatin and group B Sox binding. I found that, although the sequences, expression patterns and overall transcriptional regulatory targets of Dichaete and SoxNeuro are highly conserved across the drosophilids, both binding site turnover and rates of quantitative binding divergence between species increase with phylogenetic distance. Elevated rates of binding conservation can be found at bound genomic intervals overlapping functional sites, including known enhancers, direct targets of Dichaete and SoxNeuro, and core binding intervals identified in previous genome-wide studies. Sox motifs identified in intervals that show binding conservation are also more highly conserved than those in intervals that are only bound in one species. Notably, regions that are bound in common by SoxNeuro and Dichaete are more likely to be conserved between species than those bound by one protein alone. However, by examining binding intervals that are uniquely bound by one protein and conserved, I was able to identify distinctive features of the targets of each transcription factor that point to unique aspects of their functions. My comparative analysis of group B Sox binding suggests that sites that are commonly bound by Dichaete and SoxNeuro, primarily at targets in the developing nervous system, are highlyconstrained by natural selection. Uniquely bound targets have different tissue expression profiles, leading me to propose a model whereby the unique functions of Dichaete and SoxNeuro may arise from a combination of differences in their own expression patterns and the broader nuclear environment, including tissue-specific cofactors and patterns of accessible chromatin. These results shed light on the evolutionary forces that have maintained conservation of the complex functional relationships between group B Sox proteins from insects to mammals.
39
Mak, Chi-yan Angel. « Bioinformatic studies of gene regulation involving SOX9 and HOXB3 with reference to craniofacial development and other processes ». Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B37465405.
Texte intégral
40
ELANGOVAN, SUDHARSHAN. « Role of Sox6 and Coup-TFII transcription factors in the regulation of hemoglobin switching ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/59018.
Texte intégralRésumé :
Several transcription factors are essential for erythroid commitment and for differential globin gene expression during development. Sox6 and COUP-TFII are important Transcription Factors that are known to be modulators of globins genes regulation. By using a variant erythroleukemic cell line (V-K562) expressing both γ- and β- globins, we show how Sox6 and COUP-TFII are able to differentially regulate fetal versus adult globin genes. Both Sox6 and COUP-TFII binds in vitro and in vivo to the γ-globin promoter. Lentiviral mediated overexpression of Sox6 in this variant cells predominantly increases β-globin expression while COUP-TFII overexpression increases level of γ-globin expression. Co-transduction of Sox6 and COUP-TFII at different levels proportionately alters the balance between γ- and the β-globin expression suggesting that their differential expression could able to influence the switch. In line with these results, mouse embryonic fetal liver cells during the switching time (from E 11.5-13.5) show an increase in the level of Sox6 during development and a parallel decrease in the level of COUP-TFII expression. Preliminary experiments in human erythroid cultures from peripheral blood indicate that at low levels of COUP-TFII transduced cells, COUP-TFII overexpression increases the γ-globin expression level indicating COUP-TFII as a prospective target whose modulation can increase γ-globin expression.
41
Zalzali, Hassan. « Etude du rôle du facteur de transcription SOX9 dans les cellules tumorales intestinales ». Montpellier 2, 2008. http://www.theses.fr/2008MON20133.
Texte intégralRésumé :
SOX9 appartient à la famille des facteurs de transcription à domaine HMG (High Mobility Group), responsable de sa liaison à l'ADN. Dans l'épithélium intestinal, SOX9 est exprimé dans les cellules indifférenciées du fond des cryptes. Par ailleurs, SOX9 est présent dans toutes les lignées de cellules tumorales intestinales (CTI) que nous avons étudiées. Ceci est probablement dû au fait que le gène de SOX9 est régulé par la voie de signalisation Wnt/β-caténine qui est constitutivement active dans 80% des tumeurs colorectales. Paradoxalement, nous avons montré au laboratoire que SOX9 diminue la prolifération cellulaire et augmente l'apoptose. Notre travail a consisté à étudier le rôle de SOX9 dans les CTI. Nous avons identifié la première cible transcriptionnelle directe de SOX9 dans l'épithélium intestinal. Il s'agit du suppresseur de tumeur CEACAM1 (carcinoembryonic antigen-related cell adhesion molecule 1) qui fait partie de la superfamille des immunoglobulines. En effet, SOX9 augmente son expression en interagissant avec une séquence de haute affinité située à 1. 4kb en aval de la séquence codante. Dans la mesure où SOX9 est présent dans les CTI, comment expliquer alors qu'il diminue la prolifération cellulaire, augmente l'apoptose et augmente l'expression d'un suppresseur de tumeur (CEACAM1)? Nous avons montré que l'activité endogène de SOX9 est faible dans les CTI. Nous avons par la suite mis en évidence MiniSOX9, un variant d'épissage de SOX9, qui inhibe l'activité de SOX9 par effet dominant négatif. Ceci suggère qu'il pourrait exister un antagonisme entre SOX9 et MiniSOX9 qui, peut être, serait impliqué dans la tumorigenèse coliqueIn the intestinal epithelium, the HMG-box transcription factor SOX9 is expressed in the undifferentiated cells from the bottom of the crypts. SOX9 is present in all colorectal cancer cells (CRCC) lines that we have studied. This is probably due to the fact that SOX9 gene is regulated by the Wnt / β-catenin signaling pathway that is constitutively active in 80% of colorectal tumors. Paradoxically, we have shown in the laboratory that SOX9 decreases cell proliferation and increased apoptosis. The aim of our work was to study the role of SOX9 in the CRCC. We have identified the tumor suppressor CEACAM1 (carcinoembryonic antigen-related cell adhesion molecule 1) as the first direct transcriptional target of SOX9 in the colon epithelium. CEACAM1 is a member of the immunoglobulin superfamily. Indeed, SOX9 increases CEACAM1 expression by interacting with a high affinity sequence, 1. 4kb downstream of the coding sequence. Since SOX9 is present in CRCC, how to explain that it decreases cell proliferation, increases apoptosis and increases the expression of a tumor suppressor (CEACAM1)? We have shown that endogenous SOX9 activity is weak in CRCC. We then highlighted MiniSOX9, a SOX9 splicing variant that inhibits SOX9 activity by a dominant negative effect. This suggests that an antagonism might exist between SOX9 and MiniSOX9 that could be implicated in colon tumorigenesis
42
Mak, Chi-yan Angel, et 麥志昕. « Bioinformatic studies of gene regulation involving SOX9 and HOXB3 withreference to craniofacial development and other processes ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B37465405.
Texte intégral
43
Mirczuk, Samantha Mary. « The role of transcriptional factors GCMB, SOX3 and GATA3 in parathyroid developmental disorders ». Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533838.
Texte intégral
44
Lee, Ching-Jung. « Sox related genes in cerebellar tumours and developing cerebellum : including the identification of a new family of sox-related transcription factor ». Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250589.
Texte intégral
45
CANTU', CLAUDIO. « The Sox6 transcription factor : its role in human and murine erythroid differentiation and mechanisms for its regulation ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2009. http://hdl.handle.net/10281/8374.
Texte intégralRésumé :
To identify new genes functionally involved in erythropoiesis during development and maturation, we analysed by DNA microarray three cell populations of different maturity during mouse fetal liver development (E11.5 - E13.5). Among genes whose expression increases in parallel with erythroid maturation there is Sox6, a member of the Sry–related transcription factors family.
Sox6 is known to play a major role in erythropoiesis: its ablation in mouse causes a strong relative increase of the expression of embryonic (εy) versus other non-alpha globin genes in late gestation, and a high number of circulating nucleated and misshapen erythrocytes.
To study the role of Sox6 in human erythropoiesis, we overexpressed it by lentiviral vector transduction both in the K562 erythroleukemic cell line and in human primary CD34+ cord blood cells .
Sox6 induces significant differentiation in both models as shown by morphological and FACS analysis. Moreover, several erythroid specific transcripts are greatly increased , i.e. mRNAs for enzymes controlling the heme-biosynthetic pathway, for transcription factors and for all globins (although the ratio between epsilon and gamma-globin is decreased), suggesting that Sox6 is a general positive regulator of erythroid genes expression.
Despite their erithroleukemic origin, K562 overexpressing Sox6 grow at a very low rate when compared with control cells, and die in culture within about ten days after transduction.
Sox6 overexpression causes in fact a strong increase of SOCS3 (suppressor of cytokine-signaling) transcript, which is known to block Jak2 signalling.
Since erythroblasts undergo cell-cycle withdrawal during terminal differentiation,
our working hypothesis is that Sox6 may induce the erythroid terminal maturation program through a block in the cell-cycle progression, possibly by acting as a repressor of the Jak signalling pathway.
We then used the Sox6 consensus from the εy-globin promoter to perform a bioinformatic genome-wide search for similar evolutionarily conserved motifs, and we found a highly conserved Sox6 consensus within the Sox6 human gene promoter itself. This sequence is bound by Sox6 in-vitro and in-vivo, and mediates transcriptional repression in transient transfections in human erythroleukemic K562 cells. Moreover, the binding of a lentiviral transduced Sox6FLAG protein to the endogenous Sox6 promoter is accompanied, in erythroid cells, by a strong downregulation of the endogenous Sox6 transcript.
Finally, we demonstrated that Sox6 expression, in human erythroid cultures and in mouse bone marrow cell populations, peaks at the erythroblast stage and decreases along with erythroid differentiation. Together these observations suggest that the negative Sox6 autoregulation mediated by the double Sox6 binding site within its own promoter, might be relevant to control the Sox6 transcriptional downregulation observed in late erythroid maturation
46
Gallagher, Kayleigh M. « Identification of ESRRB and SOX2 as novel mediators of the glucocorticoid response in acute lymphoblastic leukemia ». eScholarship@UMMS, 2020. https://escholarship.umassmed.edu/gsbs_diss/1093.
Texte intégralRésumé :
Resistance to glucocorticoid (GC) therapy results in poor prognosis for acute lymphoblastic leukemia (ALL) patients. Utilizing a whole genome shRNA screen our lab identified several novel mechanisms of GC resistance. My thesis work established that an orphan nuclear receptor, the Estrogen Related Receptor Beta (ESRRB), is critical for induction of apoptotic genes following treatment with the GC dexamethasone. ESRRB has mostly been implicated in maintenance of pluripotency in mouse embryonic stem cells. We find that repression of ESRRB results in GC resistance in ALL and define ESRRB as a novel cooperating transcription factor in GC-induced gene expression. We also show that agonists to ESRRB synergize with dexamethasone and increase dexamethasone induced apoptosis in relapse ALL patient samples.
Interestingly, our shRNA screen identified another factor important in stem cell maintenance: SOX2. While we originally hypothesized that ESRRB and SOX2 may cooperate in ALL, RNA-sequencing studies revealed that these factors mediate GC resistance by independent mechanisms. Our data define SOX2 as a repressor of key signaling pathways in ALL. Upon SOX2 knockdown, we observe activation of pro-survival gene expression including activation of the MAPK pathway, which has previously been implicated in GC resistance. MAPK activation may be explained by an increase in EGFR expression observed in Sox2 knockdown cells and GC resistant patients, suggesting EGFR inhibitors may re-sensitize patients to GCs. Overall my thesis work identifies mechanisms of GC resistance in ALL and utilizes these findings to define novel therapeutic strategies for GC resistant ALL patients.
47
Bastide, Pauline. « Les rôles du facteur de transcription SOX9 dans le contrôle de l'homéostasie de l'épithélium intestinal ». Montpellier 1, 2007. http://www.theses.fr/2007MON13513.
Texte intégralRésumé :
Dans l’épithélium intestinal, Sox9 est spécifiquement exprimé par les cellules souches/progénitrices et les cellules de Paneth. L'expression de Sox9 est contrôlée par la voie Wnt/b-caténine qui joue un rôle central dans le contrôle de l’homéostasie intestinale. Cependant, les processus moléculaires qui assurent la spécificité des réponses cellulaires à ces signaux restent à identifier. Afin d’analyser la fonction de Sox9 in vivo, nous avons généré des souris dont l’épithélium intestinal est déficient en Sox9. En l‘absence de Sox9 des défauts de la différenciation sont observés tout le long de l’épithélium intestinal. De plus, une hyperplasie généralisée des cryptes et des cryptes d’apparence dysplasique, dans lesquelles, des gènes cibles de la voie de signalisation Wnt sont surexprimés, ont également été observées dans l’épithélium intestinal des souris déficientes en Sox9. Les résultats obtenus au cours de ma thèse ont permis de déterminer le rôle central de Sox9, non seulement en tant que cible transcriptionnelle de la voie Wnt canonique, mais aussi en tant que régulateur de cette voie de signalisation pour le contrôle de l’homéostasie de l’épithélium intestinalThe HMG-box transcription factor Sox9 is expressed in the intestinal epithelium, specifi cally, in stem/ progenitor cells and in Paneth cells. Sox9 expression requires an active β-catenin–Tcf complex, the transcriptional effector of the Wnt pathway. This pathway is critical for numerous aspects of the intestinal epithelium physiopathology, but processes that specify the cell response to such multipotential signals still remain to be identifi ed. We inactivated the Sox9 gene in the intestinal epithelium to analyze its physiological function. Sox9 inactivation affected differentiation throughout the intestinal epithelium, with a disappearance of Paneth cells and a decrease of the goblet cell lineage. Additionally, the morphology of the colon epithelium was severely altered. We detected general hyperplasia and local crypt dysplasia in the intestine, and Wnt pathway target genes were up-regulated. These results highlight the central position of Sox9 as both a transcriptional target and a regulator of the Wnt pathway in the regulation of intestinal epithelium homeostasis
48
D'ANGELO, DONATELLA. « FUNCTIONAL CHARACTERIZATION OF SOX TRANSCRIPTION FACTORS IN ZEBRAFISH ANGIOGENESIS AND LYMPHANGIOGENESIS : KNOCKDOWN AND KNOCKOUT APPROACHES ». Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/569898.
Texte intégralRésumé :
My laboratory is interested in studying Sox (Sry-related HMG box) proteins, a family of
transcription factors (TFs) present throughout the animal kingdom and important for the
regulation of several fundamental processes during development (Pevny and Lovell-Badge,
1997; Wegner, 1999; Bowles et al., 2000). In particular, we focused on SOX18 that, together
with SOX7 and SOX17, belongs to the SoxF subgroup (Bowles et al. 2000). In humans,
mutations in SOX18 are associated with the Hypotrichosis-Lymphedema-Telangiectasia
(HLT) syndrome, combining defects in hair, blood vessels and lymphatic development
(Irrthum et al., 2003). In zebrafish, Sox18 and Sox7 have a redundant role in regulating
arterio-venous differentiation (Cermenati et al. 2008; Herpers et al. 2008; Pendeville et al.
2008; Hermkens et al. 2015), while only Sox18 is involved in lymphatic development
(Cermenati et al., 2013). However, a recent article questioned the relevance of Sox18 role in
zebrafish lymphatic vessel development, because a sox18 mutant did not show a lymphatic
phenotype (van Impel et al. 2014). To clarify Sox18 role in zebrafish lymphangiogenesis, we
made use of a new, independent mutant allele: sox18sa12315. In vivo analyses show that sox18
mutant behaves as a null, indeed sox18 mutation, associated with sox7 perturbation, causes
the absence of trunk tail circulation, the same phenotype observed in sox7/sox18 double
partial morphants and in sox7/sox18 double mutants (Cermenati et al., 2008; Hermkens et al.
2015). Our data also point out that Sox18 has a conserved role in zebrafish
lymphangiogenesis, with an interplay with VegfC in the formation of the thoracic duct (TD).
The analyses of sox18sa12315 mutation in two transgenic backgrounds reveal that, even if the
mutation does not cause strong alterations of lymphatic system development, TD defects are
statistically significant in homozygotes. Perturbation of Vegfc signaling exacerbates TD
defects in a genotype-dependent manner; TD defects are highly enhanced in homozygotes,
but even heterozygotes show statistically significant alterations when vegfc is slightly
perturbed. The ectopic expression of sox7 in the posterior cardinal vein (PCV), from which
lymphatic precursors originate, can explain the only subtle lymphatic defects observed in
sox18 mutants transgenic line used for TD analyses. However, sox7 ectopic expression is not
seen in all the fish lines we have analyzed, suggesting that also in zebrafish, as in mouse, the
fine regulation of soxF genes depends on the genetic background.
On the other hand, we are interested in studying the complex interplay between Sox and
Notch signaling. This year we published a collaborative article showing, with knockdown
and knockout approaches, that SoxF transcription factors positively regulate notch1b and
Notch1 vascular expression in zebrafish and mouse, respectively (Chiang et al., 2017). This
work identifies SoxF responsive enhancers in Notch1 and notch1b loci in mouse and in
zebrafish, respectively. SoxF binding to the zebrafish notch1b enhancer is functionally
relevant: arterial ISV defects are indeed found in enhancer mutants under experimental
conditions, which slightly perturb Notch signaling.
My laboratory is also interested in studying the role of sox13 (subgroup D), a gene vaguely
linked to angiogenesis in different models (Roose et al., 1998; McGary et al. 2010). We have
the evidence that Sox13 is implicated in zebrafish angiogenesis and that SoxF positively
regulate sox13 (subgroup D) endothelial expression. In particular, sox13 morphants show
ISV defects and an upregulation of some genes implicating in the Notch pathway. In vivo
SPIM time lapse was used to characterize in a dynamic way, through long-term time lapse
analysis, the ISV defects observed in sox13 morphants. With a combination of knockdown
approaches in zebrafish and overexpression studies in vitro on ECs, we gathered evidence of
an involvement of Sox13 in promoting endothelial cell migration.
Finally, we confirmed that SoxF positively regulate sox13 by performing ISH analyses both
in morphants and mutants.
Since SoxF positively regulate the Notch signaling and positively regulate the expression of
sox13, a negative regulator of the Notch pathway, we can speculate the existence of a
complex regulatory network between SoxF and Sox13 in fine-tuning vascular development.
49
Ebadi, Diba. « "Role of SRY-related HMG box (SOX)-7 in Skeletal Muscle Development" and "Effect of an extracellular matrix on skeletal and cardiac muscle development" ». Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20348.
Texte intégralRésumé :
A complex network of transcription factors, which are regulated by signalling molecules, is responsible in coordinating the formation of differentiated skeletal and cardiac myocytes from undifferentiated stem cells. The present study aims to understand and compare the transcriptional regulation of skeletal and/or cardiac muscle development in the absence of Sox7 or in the presence of a collagen-based matrix in P19 embyonal carcinoma (EC) and mouse embryonic stem (ES) cells.
First, knock-down of Sox7 , by shRNA, in muscle inducing conditions (+DMSO) and in the absence of RA (-RA), decreased muscle progenitor transcription factor and myogenic regulatory factor (MRF) levels, suggesting that Sox7 is necessary for myogenesis. However, knock-down of Sox7 in the presence of RA (+RA) and DMSO increased expression of muscle progenitor markers and MRFs, suggesting that Sox7 is inhibitory for myogenesis +RA. Furthermore, Sox7 overexpression enhanced myogenesis -RA, but inhibited myogenesis and enhanced neurogenesis +RA. These results suggest an important interplay between RA signalling and Sox7 function during P19 differentiation.
Second, Q-PCR analysis showed that compared to the mouse ES cells differentiated on the regular TC plates, differentiation on the collagen matrices had a higher expression of skeletal and cardiac precursors, MRFs and terminal differentiation markers. Collagen alone enhanced myotube formation. The enhanced collagen matrix, containing the oligosaccharide sialyl LewisX (sLeX), specifically enhanced cardiomyogenesis.
These studies have added to our understanding of the transcriptional regulation of premyogenic mesoderm factors and the role of Sox7 in this process. In addition these studies provide a vision for possible use of biomaterials in directed differentiation of stem cells for the purpose of cell therapy.
50
Paul, Mandy [Verfasser], et Michael [Akademischer Betreuer] Wegner. « The role of transcription factors Sox4 and Sox11 in mouse heart development / Mandy Paul. Gutachter : Michael Wegner ». Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1075834171/34.
Texte intégral