Dissertations / Theses on the topic 'Cell biology, n.e.c'
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Lumngwena, Evelyn Ngwa. "The impact of HIV-1 subtype C Envelope N-glycosylation on DC-SIGN meditated modulation of DC function to facilitate transmission or enhance viral pathogenesis." Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27096.
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N-glycosylation plays an important role in Envelope (Env) function and may be involved in the modulation of the immune response to HIV-1 infection. In this study, we hypothesized that Env N-glycosylation may affect viral pathogenesis by influencing Env structure and function. Furthermore, we also postulated that differences in Env glycosylation could affect interactions between Env and DC-SIGN of dendritic cells (DCs), activating alternative signalling pathways which stimulate the release of different immune modulators. We generated pseudovirus of eighteen Env clones (PSVs) with variable number and position of potential N-glycan sites (PNGs) and compared their ability to infect TZM-bl cells, bind to Raji+ DC-SIGN cells, trans-infect TZM-bl cells when captured by either Raji-DC-SIGN cells or monocyte-derived dendritic cells (MDDCs) and modulate MDDC signaling by investigating the release of Interleukin-10 (IL-10) and other immune modulatory cytokines and MAPK activation. Entry efficiency, DC-SIGN binding and trans-infection varied widely across all clones. The level of IL-10 secreted by MDDCs in response to PSV stimulation varied 32-fold. The induction of IL-10 secretion by purified gp140 confirmed that Env was the viral component that stimulated the secretion of IL-10 via interaction with DC-SIGN and potentially other undefined receptors. PSV and purified gp140 stimulated MDDC signaling via ERK and JNK phosphorylation, while p38 was not activated. The addition of recombinant DC-SIGN lowered the levels of secreted IL-10 and ERK /JNK phosphorylation, suggesting that DC-SIGN plays a role in these responses. As Env mannosylation correlated with DC-SIGN binding, five highly conserved Env PNGs (241, 262, 386, 392, and 448) previously identified to carry high mannose type N-glycans and hence thought to be involved in DC-SIGN binding were deleted in two Env clones by site-directed mutagenesis to confirm their importance in Env function. The potential role of these PNGs in Env entry efficiency, DC-SIGN binding, trans-infection, induction of MDDC IL-10 secretion and activation of MAPK phosphorylation was determined. Deletion of these sites significantly affected the entry efficiency, DC-SIGN binding, trans-infection and MDDC IL-10 secretion, with one Env clone proving to be more sensitive to mutation than the other. This suggests that PNGs influence Env function in a clone-specific manner. As deletion of highly conserved PNGs abrogated Env function we used sequence analysis to identify PNGs involved in binding DC-SIGN and inducing MDDC IL-10 secretion. We grouped PSVs based on the presence or absence of specific PNGs in Env sequences and compared entry efficiency, DC-SIGN binding, trans-infection, stimulation of MDDC IL-10 secretion and induction of MAPK phosphorylation. Three Env PNGs were significantly associated with entry efficiency (N356, N392, and N674), and three sites (N289, N356 and 674) were significantly associated with trans-infection while N674 also influenced DCSIGN binding. The majority of MDDC donors secreted higher levels of IL-10 when stimulated with PSVs that carried PNGS at N130 (p = 0.0016) and N332 (p = 0.0039) and lacked N674 (p = 0.033). When Envs were graded on whether they had 0, 1, 2 or 3 of the PNGs (e.g. -130, -332, +674; -130, +332 and +674, etc.) those that carried either one of the PNGs or the entire induction motif (N130+ N332+ N674-) significantly stimulated MDDCs to secrete higher levels of IL-10 than those that completely lacked the motif (p = 0.0335 and p = 0.0304, respectively). As the presence of N674 was linked to reduction in all functions of Env, it is likely that the presence of an N-glycan at this site affected Env structure and could skew the analysis. Excluding N674 indicated that the presence of PNGs at position 130 and 332 was sufficient to induce significantly higher IL-10 release than those that had either none or one of these sites (p = 0.0053). When we determined whether N130 and N332 were enriched in subtype C acute infection Envs, these sequences were not enriched with PNGs at either N130 or N332 compared to chronic infection viruses. However, when IL-10 levels were compared between MDDC donors stimulated with PSV of either acute or chronic infection clones, those from early infection significantly enhanced MDDC secretion of IL-10 (p = 0.0039). This suggests that even though PNGs at 130 and N332 could be involved in inducing MDDC IL-10 secretion, it is not the only requirement for enhanced stimulation. Although Env differentially activated ERK and JNK phosphorylation, ERK phosphorylation did not correlate with IL-10 secretion, suggesting that this MAPK signaling pathway was not solely responsible for triggering the release of MDDC IL-10 and other regulatory cytokines. PSVs also stimulated the release of TNFα, IL-1β, IL-6, IL-8, MIP-1a, and MIP-1b while having no effect on IL-12 levels. This suggests that HIV-1 binding to DCs in the genital tract could change the dynamics of DC immune responses, deregulating their cytokines secretion and destabilising the Th0 cell differentiation to facilitate viral survival and thus productive clinical infection. We therefore conclude that HIV-1 variants differentially stimulate MDDCs to release immunosuppressive IL-10 and that transmitted founders could be better at modulating immune responses in the genital tract compared to chronic infection variants.
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Smith, Abigail O. "Defining the Role of c-Jun N-terminal Kinase (JNK) Signaling in Autosomal Dominant Polycystic Kidney Disease." eScholarship@UMMS, 2021. https://escholarship.umassmed.edu/gsbs_diss/1141.
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Polycystic kidney disease is an inherited degenerative disease in which the uriniferous tubules are replaced by expanding fluid-filled cysts that ultimately destroy organ function. Autosomal dominant polycystic kidney disease (ADPKD) is the most common form, afflicting approximately 1 in 1,000 people. It primarily is caused by mutations in the transmembrane proteins Polycystin-1 (PKD1) and Polycystin-2 (PKD2). The most proximal effects of polycystin mutations leading to cyst formation are not known, but pro-proliferative signaling must be involved for the tubule epithelial cells to increase in number over time. The stress-activated mitogen-activated protein kinase (MAPK) pathway c-Jun N-terminal kinase (JNK) promotes proliferation in specific contexts and is activated in acute and chronic kidney disease. Previous work found evidence of JNK activation in cystic tissues (Le et al., 2005) and others showed that JNK signaling is activated by aberrant expression of PKD1 and PKD2 in cell culture (Arnould et al., 1998; Arnould et al., 1999; Parnell et al., 2002; Yu et al., 2010) but the contribution of JNK signaling to cystic disease in vivo has not been investigated.
This body of work describes the use of conditional and germline deletion of Pkd2, Jnk1 and Jnk2 to model ADPKD and JNK signaling inhibition in juvenile and adult mice. Immunoblots and histological staining were used to measure JNK activation and evaluate the effect of JNK deletion on cystic disease. Results show that Pkd2 deletion activated JNK signaling in juvenile and adult mice. Reduction of JNK activity significantly reduced cystic burden in kidneys of juvenile Pkd2 mutant mice. This correlated with reduced tubule cell proliferation and reduced kidney fibrosis. The improvement in cystic phenotype was driven primarily by Jnk1 deletion rather than Jnk2. JNK signaling inhibition in adult Pkd2 mutants significantly reduced liver cysts when mice were aged six months. JNK inhibition reduces the severity of cystic disease caused by the loss of Pkd2 suggesting that the JNK pathway should be explored as a potential therapeutic target for ADPKD.
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Amin, Shahreen. "Regulation of the tyrosine phosphatase SHP-1 expression by C-jun-N-terminal kinase and RFX-1 and AP-4 transcription factors in insulin-like growth factor-1 (IGF-1) stimulated breast adenocarcinoma MCF-7 cells." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/26837.
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This thesis is devoted to reveal the negative regulators in IGF-1 (Insulin like growth factor 1) stimulated growth of a human breast adenocarcinoma cell line. It is a well established fact that increased circulating levels of IGF-1 correlate with increased risk of breast cancer. IGF-1 activation of its receptor, IGF-1R, is implicated in the progression of breast cancer, where IGF-1 stimulation leads to proliferative and anti-apoptotic responses by stimulating MAPK Erk and PI3K, respectively. In this study, IGF-1 stimulated MCF-7 cells proliferated more in the absence of MAPK JNK, implicating the involvement of MAPK JNK in the negative regulation of IGF-1 stimulated cell growth.
In this research study, we show for the first time that IGF-1 stimulation of breast cancer cells induces SHP-1-expression by activating JNK, which in turn, activates RFX-1 and AP-4 transcription factors to allow them to bind to the high-expression region of the SHP-1 P-1 promoter in breast adenocarcinoma MCF-7 cells. (Abstract shortened by UMI.)
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Souyri-Caporale, Michèle. "Etude du pouvoir tumorigene de l'oncogene n-ras." Paris 7, 1987. http://www.theses.fr/1987PA077083.
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Gavériaux, Claire. "Etude de l'interaction entre l'immunoglobuline e et son recepteur de forte affinite : mise au point d'un nouvel essai immunoenzymatique sur cellules, le celisa, importance de la n-glycosylation et de l'activation de la proteine kinase c dans l'expresion fonctionnelle de ce recepteur." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13014.
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Baalbaki, Zein El-A. "Vibrational relaxation of N₄O, C₄H₄, and C₄H₄-Ar mixtures." Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/4666.
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Lloyd-Evans, Emyr. "Cell biology of Niemann-Pick type C disease." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437185.
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Co, Carl. "N-WASP at the membrane-actin interface." Diss., Search in ProQuest Dissertations & Theses. UC Only, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3251943.
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Angers-Loustau, Alexandre. "Roles of c-Src and hDRR1 in glioma cell invasion." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85118.
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Malignant glioma is the major brain tumor in adults, and has a poor prognosis. The failure to control invasive cell subpopulations may be the key reason for local glioma recurrence after radical tumor resection, and may contribute substantially to the failure of the other treatment modalities, such as radiation therapy and chemotherapy. As a model for this invasion, we have implanted spheroids from a human glioma cell line (U251) in three-dimensional collagen type I matrices which these cells readily invade. First, we observed that the Src family kinase specific pharmacological inhibitors PP2 and SU6656 significantly inhibited the invasion of the cells in this assay, which was then confirmed by expression of two inhibitors of Src family function, dominant inhibitory Src and CSK. Fluorescent time-lapse microscopy on U251 cells stably expressing a YFP-actin construct shows that PP2 caused the disappearance of peripheral membrane ruffles within minutes in monolayer cultures, and induced the loss of actin bursting at the leading tip of the invadopodium in three-dimensions. The inhibition of Src family activity is thus a potential therapeutic approach to treating highly invasive malignant glioma. In the second part, we analyze the role of a novel protein, hDRR1, which was cloned from a functional screen of genes involved in glioma cell hyperinvasion. We show that hDRR1 localizes endogenously and when overexpressed to the actin cytoskeleton, via two independent but homologous actin-localization domains. We also show that the C-terminus of hDRR1 can bind to the light chain of MAP1A and MAP1B, and that hDRR1 overexpression in invading glioma cells results in a decrease in the percentage of cells adopting a polarized morphology. These results suggest that hDRR1 represents a novel actin-tubulin bridging protein that plays important roles in cytoskeletal events.
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McLachlan, Ian Gordon. "Genetic control of dendrite morphogenesis in C. elegans." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493511.
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The shapes and attachments of cells determine the machinery of organs; for example, the shapes and attachments of neurons and glia establish the wiring of the brain. To understand how neuronal dendrites obtain their morphologies and make the appropriate connections, we used C. elegans sense organs as models. Previous work identified a requirement for the extracellular matrix protein DYF-7 in dendrite extension: DYF-7 anchors dendrites dendrite endings at the embryonic nose while neuronal cell bodies migrate away, and in its absence, dendrites fail to extend. Here, we show that these dendrites are part of a sensory epithelium composed of glial cells and neurons. The dendrites are ensheathed by glial cells, form adherens junctions onto glia, and are stabilized at their apical surfaces by the extracellular matrix protein DYF-7. In dyf-7 mutants, the pulling force of cell migration causes this sensory epithelium to rupture along the glia:glia junctions. By comparison, dendrites of the URX and BAG neurons are intimately connected to the external surface of glial cells but are not known to form adherens junctions and are not affected in dyf-7 mutants. To identify factors required for URX and BAG dendrite extension, we performed forward genetic screens for dendrite extension defects in these cells and identified mutations in the cytoplasmic protein GRDN-1/Girdin and the adhesion molecule SAX-7/L1CAM. We show that in wild-type embryos, URX and BAG dendrites also extend by attaching to the nose and then stretching during embryo elongation but, in grdn-1 embryos, they fail to remain attached. GRDN-1 can promote dendrite attachment by acting in glia—it localizes to glial endings and causes localized accumulation of SAX-7, creating an adhesive compartment where dendrites attach. Thus, GRDN-1 and SAX-7 determine dendrite length by positioning a neuron-glia attachment site that couples dendrite extension to embryonic growth. Finally, we identified several other mutants with URX dendrite morphogenesis defects, including overgrowth of the URX dendrite; some have been mapped to genes associated with the cytoskeleton. Together, these studies define genetic mechanisms that control morphogenesis of distinct classes of sensory dendrites through specific adhesive interactions with their glial neighbors.Medical Sciences
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Dearth, Lawrence. "Characterization of C/EBPs in Mammary Epithelial Cell Biology." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1038840268.
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Dearth, Lawrence R. "Characterization of C/EBPs in mammary epithelial cell biology /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486463803601699.
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Marais, Saberi. "XvVHA-c``1- a novel stress responsive V-ATPase subunit c`` homologue isolated from the resurrection plant Xerophyta viscosa Baker." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/4291.
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Driscoll, Kaitlin B. (Kaitlin Bridget). "Genetic and molecular studies of cell-autonomous execution during programmed cell death in C. elegans." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104177.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references.
Apoptosis or programmed cell death was originally defined by evolutionarily conserved morphological characteristics that include shrinkage of cell volume and chromatin condensation. Apoptosis functions as a highly controlled mechanism for the elimination of unwanted or damaged cells and is essential for disease prevention. Apoptotic cell death is a cell-autonomous process driven by the caspase family of cysteine proteases. The discovery of the CED-3 caspase in C. elegans led to the paradigm that caspase cleavage of substrates drives cell death and promotes engulfment. While many caspase substrates have been identified, it is not well understood how caspase substrates act to promote cell death and engulfment. The control of caspase activation in C. elegans is conserved among metazoans and involves the interplay of pro and anti-apoptotic BCL-2 and BH3-only family proteins. In C. elegans an increase in apoptotic cell refractility observed by Nomarski optics is one of the hallmark morphological characteristics of apoptosis. We found that the presumptive TRP channel CED-1 1 acts downstream of caspase activation in apoptotic cells to drive the increase in refractility. We discovered that CED-1 1 is also required for a decrease in cell volume and increase in nuclear permeability of apoptotic cells. We showed that CED-1 1 is required for efficient degradation of apoptotic cells and facilitates the death process, suggesting that the decrease in cell volume and/or increase in nuclear permeability could promote the death and degradation of the cell. We conclude that CED-1 1 acts downstream of caspase activation to effect multiple observed changes to apoptotic cells and to facilitate death and degradation. In addition we investigated the anti-apoptotic function of the generally pro-apoptotic BCL-2 homolog CED-9.
by Kaitlin B. Driscoll.
Ph. D.
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Higuera, Urbano M��nica. "Regulaci��n de las v��as MAPK y Akt-FoxO1 en el mecanismo molecular de acci��n del Minerval contra el c��ncer de pulm��n y glioma." Doctoral thesis, Universitat de les Illes Balears, 2012. http://hdl.handle.net/10803/84084.
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Ghilamicael, Amanuel Menghs. "Isolation and characterization of n-alkane utilizing bacteria, which produce biomulsifiers." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/4265.
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Includes bibliographical references.Bacterial strains were isolated by enrichment cultures from oil-contaminated soil samples. In the present study, several strains, capable of growing on crude oil, were isolated. Isolates were screened for their inherent abilities to produce bioemulsifiers when they were grown on hydrocarbon substrates.
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Ouellet, Jimmy. "Control of cell division and quiescence during «C. elegans» developement." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18654.
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The development of the nematode C. elegans is invariant allowing investigators to use genetic analysis in this model system to identify components of many critical developmental pathways. The Roy laboratory uses this strategy to identify genes that control cell division throughout the course of development. My work focusses on the intestinal lineage due to their typical cell division pattern. Using genetic analysis, I have characterized the role of genes that affect the transition from mitosis to karyokinesis and finally endoreplication that occurs in the intestinal cells post-embryonically during the first larval stage. Five mutants that were isolated are grouped into classes that have more (rr33 and rr45) or less (rr42, rr43 and rr44) intestinal nuclei than wild-type. I cloned both mutants with more intestinal nuclei (rr33 and rr45) to show that they encode lin-35, the homologue of the Retinoblastoma gene and a highly conserved gene referred to as nol-10 respectively. I showed that lin-35 interacts with RNAi pathway components to properly repress genes required for this transition. I also found that met-2, the homologue of the Suv39h methyl transferase as well as the heterochromatin protein-like hpl-1 and hpl-2 are required to maintain the repression of these loci. Moreover, during my characterization of the typical cell cycle arrest observed during the dauer stage, I found that the Notch ligand lag-2 is specifically expressed in 6 Inter Labial neurons 2 (IL2) at the onset and throughout the dauer stage. I demonstrated that this expression pattern reflects the requirement of the canonical Notch pathway to properly maintain the dauer stage and specific expression of the Notch receptor glp-1 in a subset of neurons is able to rescue the defect in dauer maintenance in glp-1 mutants. Therefore, the Notch pathway is not required for neuronal cell fate specification since there is no cell division at this stage but rather serves a novel function that may inPuisque son développement ne varie pas, le nématode C. elegans est un organisme pouvant servir de modèle génétique pour identifier des gènes requis dans bon nombre de processus. De ce fait, le laboratoire du Dr Roy utilise cet organisme pour identifier des gènes qui régulent la division cellulaire durant son développement. L'isolement de 5 mutants, qui influencent la division cellulaire de l'intestin, m'a permis de caractériser le rôle de ces gènes dans la transition de la mitose vers la karyokinèse, puis vers l'endoréplication. Cette transition est spécifique aux cellules intestinales à la fin du premier stade larvaire du développement post-embryonnaire. Ces cinq mutants ont été groupés soit dans la classe de mutants avec plus de noyaux intestinaux que la souche sauvage (rr33 et rr45), soit dans celle en contenant moins (rr42, rr43 et rr44). Le clonage des mutants contenant plus de noyaux intestinaux m'a permis d'observer l'influence de la mutation rr33 sur le gène lin-35, l'homologue du gène du rétinoblastome chez l'humain, et de rr45 sur le gène nol-10. Je démontre que lin-35 interagit avec les composantes de la voie RNAi afin de permettre la répression des gènes requis pour la transition du cycle cellulaire des cellules intestinales. Mes résultats permettent également d'observer le rôle de met-2, un homologue de la méthyltransférase Suv39h et de deux protéines hétérochromatiques hpl-1 et hpl-2, dans le maintien de cette répression. De plus, j'ai pu constater que, durant ma caractérisation de l'arrêt du cycle cellulaire propre au stade dauer, le ligand Notch lag-2 est spécifiquement exprimé au début et durant tout ce stade dans 6 neurones Inter Labial 2 (IL2). J'ai pu démontrer que l'expression de ce ligand correspond au besoin de la voie de signalement canonique Notch pour maintenir ce stade de développement et aussi que l'expression du récepteur Notch glp-1 dans les neurones empêche le défaut de maintien$
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Galvin, Brendan D. (Brendan Daniel). "The regulation of programmed and pathological cell death in C. elegans." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38633.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, February 2007.Includes bibliographical references.
Programmed cell death, or apoptosis, is important in the development and homeostasis of metazoans. In the nematode C. elegans, four genes, egl-1, ced-9, ced-4, and ced-3, constitute the core pathway acting in all somatic programmed cell deaths. This pathway is evolutionarily conserved in humans. The BH3-only protein EGL-1 is transcriptionally upregulated in cells fated to undergo programmed cell death, and EGL-1 blocks cell-death inhibition by the cell-death regulator CED-9, a Bcl-2 family member. The binding of EGL- 1 to CED-9 releases the Apaf- 1-like adaptor protein CED-4 from CED-9, so that CED-4 can activate the caspase CED-3, a protease that is the effector of programmed cell death. In this thesis, I describe three projects, each of which examines one aspect of C. elegans cell death. From. screens for mutations that increase cell death in a sensitized genetic background, I identified a gene that protects cells from programmed cell death.
(cont.) This gene, spk-1, encodes a homolog of SR protein kinases, which regulate alternative splicing. Previous work has shown that ced-4 pre-mRNA is alternatively spliced to generate two transcripts that function oppositely in cell death. I found that spk-1 regulates ced-4 transcript splicing, thereby influencing the amount of programmed cell death that occurs. From a screen for genes that promote programmed cell death, I isolated a mutation in a conserved non-coding element in the transcriptionally regulated cell-death activator gene egl-1. This element regulates the deaths of specific cells in the C. elegans ventral nervous system. I found a novel C. elegans transcription factor, Y38C9A. 1, that binds this element and might function to regulate egl-1 transcription and programmed cell death in the ventral nervous system. In addition to the programmed cell deaths that occur in C. elegans, pathological death of specific cells can be caused by mutations in some genes. I characterized two genes, lin-24 and lin-33, that can mutate to cause the inappropriate death of specific hypodermal blast cells. One of these genes, lin-24, contains a domain similar to that found in some bacterial toxins.
(cont.) By morphological and genetic criteria, I show that the lin-24- and lin-33-mediated deaths are unlike previously characterized necrotic and apoptotic cell deaths in C. elegans. These deaths require some of the genes responsible for engulfing the corpses generated by programmed cell death, even though the deaths do not require the core genes of the genetic pathway of programmed cell death.
by Brendan D. Galvin.
Ph.D.
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Chen, Xiulian. "The negative impact of copper deficiency upon cardiac and C₂C₁₂ cell mitochondria biology /." Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.
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Rico, Vargas Sergio Arturo. "Regulation and dysregulation of B lymphopoiesis in mouse bone marrow: in vivo role of macrophage activation (pristane-treatment and malaria-infection), c-myc, c-kit, and immunoglobulin genes." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41340.
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To examine factors influencing normal and disordered genesis of the B lymphocyte lineage in mouse bone marrow, precursor B cell dynamics have been analysed in conditions predisposing to B cell neoplasias and deficiencies. Double immunofluorescence labeling and stathmokinetic techniques have been used to quantitate the population size and mitotic activity of pro-B cells before $ mu$ chain expression, pre-B cells expressing cytoplasmic $ mu$ chains, and B lymphocytes expressing surface IgM. Two conditions associated with prolonged macrophage activation and B cell neoplasia, pristane oil-treatment and malaria infection, have been found to stimulate the proliferation of pro-B cells but to produce increased cell loss at later cell differentiation stages, suggesting that the stimulation of cells undergoing Ig gene rearrangement may predispose to genetic errors leading to cell death or oncogenesis. During a pretumorous period in E$ mu$-myc transgenic mice a marked stimulation of pro-B and pre-B cells is associated with much subsequent cell loss, suggesting that additional mutations are needed to promote B cell survival and the emergence of a tumorigenic clone. Many early precursor B cells express c-kit but their development is not blocked by a neutralizing anti-c-kit antibody in vivo, suggesting that the role of c-kit can be replaced by alternative signalling systems. The introduction of Ig transgenes in scid mutant mice, unable to rearrange endogenous Ig genes, shows that the survival of successive stages in precursor B cell development depends upon the successful progressive expression of the IgM molecule. The work demonstrates that processes influencing both cell proliferation and loss can be critical in regulating the genesis of both normal and potentially neoplastic B cells in the bone marrow.
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Lee, Kyung-Joo 1977. "Identification of proteins interacting with the N-termini of USP2 deubiquitinating enzyme isoforms." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81352.
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The ubiquitin system is a major cytosolic and nuclear pathway of proteolysis in all eukaryotic cells. In this pathway, ubiquitin, a 76 amino acid peptide, is covalently ligated to protein substrates by a series of enzymes; E1, E2 and E3. The ubiquitin-attached proteins are commonly targeted for destruction by the 26S proteasome but the ubiquitination may also direct other cellular functions such as endocytosis, leading to proteolysis in the lysosome. Interestingly, a large family of genes encoding deubiquitinating enzymes (UBP; ubiquitin specific processing protease and UCH; ubiquitin C-terminal hydrolase) has recently been identified from different organisms. These enzymes are found to remove ubiquitin from covalent attachments to itself or other proteins in order to regenerate free ubiquitin or to counteract the effects of ubiquitinating enzymes by removing the polyubiquitin chain from the conjugated protein substrate. Dr. Wing's laboratory has recently identified USP2a and USP2b, two germ cell specific UBP isoforms that share a common core region but divergent N-termini. These termini target the USP2b and USP2a to different subcellular locations and also influence substrate specificity.To identify substrates or interacting proteins that may serve to localize these enzymes, a bacterial two-hybrid assay was performed using a mouse testis cDNA library and the N-termini of the enzymes as baits. Kpna6, an isoform of Karyopherin alpha (also known as importin alpha) and SKD3, the suppressor of K + transport defect protein were found to be possible interacting proteins of USP2a and USP2b respectively.
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Corral, Marisol. "Caracterisation de genes cellulaires dont l'expression est associee a la cancerisation hepatique." Paris 6, 1987. http://www.theses.fr/1987PA066124.
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Kim, Saechin. "Two C. elegans genes that can mutate to cause degenerative cell death." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11945.
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Chihara, Daisuke. "An E-cadherin-mediated hitchhiking mechanism for C. elegans germ cell internalization during gastrulation." Thesis, New York University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3556984.
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We have used the C. elegans primordial gonad to understand how stem cells assemble into a niche during development. The C. elegans primordial gonad contains two somatic gonad precursor cells (SGPs) and two primordial germ cells (PGCs). The primordial gonad assembles during embryogenesis when PGCs and SGPs come together adjacent the intestine.
As a first step in understanding niche assembly, we investigated how PGCs move to the site where the primordial gonad forms. PGCs and somatic cells move into the interior during gastrulation. Because somatic cells require transcription to ingress whereas PGCs are transcriptionally quiescent, we hypothesized that somatic cells might push or pull the PGCs into the embryo. We used videomicroscopy to identify cells that contact the PGCs, and used laser killing to determine if the contacting cells are required for PGC ingression. The PGCs are surrounding by adjacent mesodermal cells and internal endodermal cells. We found that the only contacting cells necessary for PGC ingression were the endodermal cells, which ingress into the embryo an hour before the PGCs. Killing or altering the fate of the endodermal cells prevented PGC ingression but not ingression of other somatic cells. Using fluorescent membrane markers and live imaging, we showed that PGCs and endodermal cells maintain contact throughout gastrulation, and that endodermal cells move dorsally as PGCs ingress form the ventral surface. PGCs express high levels of E-cadherin/HMR-1, and knocking down E-cadherin/HMR-1 caused PGCs to detach from endodermal cells and remain on the surface of the embryo. Finally, we show that the enrichment of HMR-1 protein in the PGCs is not due to transcriptional upregulation, but is instead due to an increase in protein expression mediated by the hmr-1 3' UTR. We propose that PGCs upregulate E-cadherin/HMR-1 to maintain tight adhesion with endodermal cells, which pull the PGCs into the embryo and position them at the site of primordial gonad assembly. Our results highlight the importance of germ cell - gut interactions during development and of E-cadherin-mediated adhesion in niche formation.
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Lu, Yu. "Cell cycle uncoupling, elimination, and functional modification of centrioles during C. elegans development." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116920.
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Centrosome duplication is coupled with cell division to ensure that centrosome is duplicated only once per cell cycle. This coupling, however, can be altered in specific developmental contexts although how this uncoupling occurs remains generally unclear. In C. elegans, the larval intestinal and the hypodermal cells will endocycles, while germ line stem cells eventually exit mitosis and enter meiosis. We use these models to better understand how the centrosome is intimately coupled to the cell cycle and the mechanisms though which the duplication of the centrioles can be uncoupled from cell division during the course of development.By monitoring the levels of SPD-2, a protein that is critical for centriole duplication in C. elegans, we found that the centriole duplicates normally at the intestinal cell nuclear division, but does not re-duplicate during the first endocycle, Subsequently SPD-2 becomes diffuse within the nucleus before it is subsequently eliminated. These dynamic changes seem to be actively regulated since they are not observed in situations of un-quantized DNA re-replication. To test whether cell cycle regulators might regulate centrosome/cell cycle uncoupling and elimination, we generated phosphomimetic and non-phosphorylable variants of SPD-2. We found that altering the highly conserved CDK-phosphorylation site of Serine 545 uncouples the centriole duplication/cell cycle coupling, whereas mimicking PLK-mediated phosphorylation or reducing the activity of ubiquitylation pathway by RNAi leads to nuclear accumulation of SPD-2 potentially by stabilizing SPD-2 without affecting centrosome duplication and uncoupling. Overall our study reveals that phosphorylation of SPD-2 by key cell cycle kinases may regulate centrosome/cell cycle uncoupling and elimination during in C.elegans development.Secondly, we studied the role of RNF-1, a RING-domain protein that interacts with Cip/Kip family member CKI-2 in C. elegans. We found that RNF-1 mediates the ubiquitylation of CKI-2, which consequently results in its proteasome-dependent degradation. Consistent with this, RNF-1 reduces the embryonic lethality caused by misexpression of CKI-2. We also found that RNF-1 is localized at nuclear periphery, although the significance of this localization still requires further characterization.Finally, we analyzed the localization and the function of γ-tubulin during germ cell progression. We found that γ-tubulin undergoes a re-distribution from its association with the centriole to germ cell membrane at the onset of meiosis. This re-distribution causes the centriole to lose its microtubule nucleating capacity and appears to be triggered by signals that occur during the mitosis-meiosis transition. We are continuing a characterization of the significance and the mechanism of this re-distribution.La duplication des centrosomes est couplé à la division cellulaire afin qu'elle n'ait lieu qu'une seule fois par cycle cellulaire. Cependant, lors de certains contextes développementaux, ce couplage n'a pas lieu et ceci reste mal compris à ce jour. Chez C. elegans, alors que les cellules hypodermales et intestinales font de l'endo-replication, les cellules souches germinales sortent de la mitose pour entrer en méiose. L'utilisation de ces différents modèles cellulaires, nous permet de mieux comprendre comment la duplication des centrosomes est dans la plupart des cas intimement couplée au cycle cellulaire, et d'étudier les mécanismes où la duplication des centrioles est indépendante à la division cellulaire au cours de contextes développementaux particuliers.SPD-2 est une protéine essentielle à la duplication des centrioles chez C.elegans. En observant ses niveaux d'expression, nous avons pu montré qu'alors que les centrioles sont correctement dupliqués lors de la division des cellules intestinales, ils ne se re-dupliquent pas au cours du 1er-cycle d'endo-replication. En effet, SPD-2 diffuse dans le noyau, avant d'être éliminé. Cette dynamique semble être activement régulée, car elle n'est pas observée dans des situations où l'ADN est très anormalement répliqué. Afin d'étudier l'importance des régulateurs du cycle cellulaire dans ce découplage centrosome/cycle cellulaire, nous avons généré des variants SPD-2, phosphomimétiques ou non-phosphorylables. De manière très intéressante, la modification de la serine 545, site très conservé pour la phosphorylation par CDK, entraine le découplage de la duplication du centriole par rapport au cycle cellulaire. Au contraire, en mimant la phosphorylation par PLK ou en diminuant l'activité de la voie de l'ubiquitylation, par ARNi, la protéine SPD-2 s'accumule dans le noyau. Cette accumulation est probablement due à la stabilisation de la protéine, mais elle n'affecte pas la duplication du centrosome. Notre étude révèle donc l'importance des phosphorylations de SPD-2 par différentes kinases clés du cycle cellulaire dans la régulation son activité. En effet, celles ci pourraient réguler le découplage de la duplication des centrosomes du cycle cellulaire et affecter leur élimination au cours du développement chez C. elegans.Parallèlement, nous nous sommes aussi intéressé au rôle de RNF-1, une protéine contenant des domaines RING qui interagit avec CKI-2, un membre de la famille Cip/Kip. Nous avons démontré que RNF-1 joue un rôle crucial dans l'ubiquitylation de CKI-2, qui est alors dégradé par la voie du protéasome. Ainsi, l'expression de RNF-1 réduit la létalité embryonnaire causée lors d'une mauvais expression de CKI-2. RNF-1 se localise à la périphérie du noyau, toutefois la fonction associée à cette localisation nécessite une étude plus approfondie.Finalement, nous avons etudié le rôle de la γ-tubuline au cours de la progression des cellules germinales. Nous avons trouvé que la γ-tubuline est redistribuée depuis sa localisation centriolaire vers la membrane cytoplasmique des cellules germinales pendant la méiose. Cette redistribution inhibe les capacités du centriole à générer la nucléation des microtubules, ceci résultant probablement de signaux transmis lors de la transition entre la mitose et la méiose. Nous continuons notre travail afin de comprendre le rôle et les mécanismes impliqués dans cette redistribution.
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Mathopa, Byatlela Abel. "Isolation of bacterial strains capable of efficient conversion of n-alkanes into value added products." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/4294.
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Includes bibliographical references.Bacteria that are capable of degrading alkane fractions, C12-C13 and C14-C17, were isolated from oil-contaminated soil collected from the petrochemical company, CALTEX Refineries, South Africa. A total of twenty-three environmental strains were isolated. A preliminary procedure, Nile Blue A straining suggested that twelve of the twenty-three environmental strains might accumulate polyhydroxyalkanoates (PHAs) in their cytoplasm, which is a good candidate for biodegradable plastics. The gene that catalyzes PHA polymerization, phaC, was detected using PCR in some of the environmental strains. The strains of interest were identified and characterized biochemically using various techniques and later sequenced by 16S rONA PCR. The environmental isolate 2 showed a 99 % identity to Pseudomonas aeruginosa BHP7 -6 and was for that reason given a name, Pseudomonas aeruginosa MB2SA. P. aeruginosa MB2SA was shown to possess a 0.5 kb internal fragment corresponding to the phaC gene and capable of degrading the alkane fractions, Cn-CI3 and CI4-CI7, effectively. P. aeruginosa MB2SA was shown to grow optimally in the long alkane fraction, Cw C17, and was further grown in pure alkanes, n-dodecane, n-tetradecane, and hexadecane for comparison. In addition, the strain, P. aeruginosa MB2SA, was grown in an appropriate medium for PHA synthesis and high yields of PHA were observed when both the long alkane fraction, Cw CI7, and pure alkane, hexadecane, were employed as sole carbon sources respectively.
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Learmont, Jessica. "Prion-like properties of the N-terminal domains of the rat and human FoxG1 transcription factors." Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/4285.
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Word processed copy.Includes bibliographical references (leaves 82-90).
The purpose of this study was to investigate the possible prion-like properties of the N-terminal domains of the winged-helix transcription factor FoxG1.
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Stanfield, Gillian Marie 1970. "Genetic analysis of timing, morphology and degradation of cell corpses in C. elegans." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85286.
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Zhao, Xi. "Cell cycle regulation : the role of the c-mos oncoprotein and the cytoskeleton /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487677267731537.
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Tiensuu, Teresa. "Cell fate specification by Ras-mediated cell signalling in C. elegans." Doctoral thesis, Umeå : Univ, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-120.
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Buchanan, Fritz G. "Endogenous Alkylglycerol Functions As a Mediator of Protein Kinase C Activity and Cell Proliferation." Digital Commons @ East Tennessee State University, 1997. https://dc.etsu.edu/etd/2885.
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To explore the possibility that 1-O-alkyl-sn-glycerol (alkylglycerol) may serve a regulatory role in the control of cell proliferation or PKC activity, we examined the ability of alkylglycerol to influence PKC activity and subcellular distribution as well as the ability of alkylglycerol to effect cell proliferation. MDCK cells grown to confluence show a loss of PKC activity associated with the membrane, as reported in fibroblasts. Preconfluent cultures of MDCK cells have a high level of PKC activity associated with the membrane. However, treatment of preconfluent cultures with alkylglycerol causes a reduction of PKC activity. A similar inhibition was observed with alkylglycerol when cells were treated with TPA, an activator of PKC. To confirm that alkylglycerol was exerting an effect directly on PKC, alkylglycerol was shown to inhibit PKC activity in vitro in a dose dependent manner. Since PKC exists as a family of closely related isozymes, we have determined the effects of growth arrest and alkylglycerol treatment on PKC $\rm\alpha,\ \epsilon,\ and\ \zeta$ (expressed in MDCK cells). The active forms of PKC $\alpha$ and $\epsilon$ are lost early in the growth of MDCK cells during the endogenous accumulation of alkylglycerol and synthetic alkylglycerol inhibits the membrane form of PKC $\alpha$ and $\epsilon.$ However, alkylglycerol inhibits the TPA induced translocation of PKC $\alpha$ but not $\epsilon$ suggesting a differential inhibition among these isoforms. Neither TPA or alkylglycerol had any effects on the distribution of PKC $\zeta.$ To examine the effect of alkylglycerol on cell proliferation, Swiss 3T3 cells were used. GLC analysis shows that 3T3 cells accumulate alkylglycerol in a similar manner as MDCK cells. Since this accumulation occurs just prior to cell growth arrest, the effects of alkylglycerol on preconfluent cells was observed. Preconfluent cultures of 3T3 cells were treated with alkylglycerol on day 1 of growth. After 8 days of culture, the treated group showed a slower growth rate and saturation density. Furthermore, after these cells were reseeded in the absence of alkylglycerol, the original growth rate and saturation density returned. Thus alkylglycerol induces a decrease in cell proliferation without causing any detrimental effects. Similarly, alkylglycerol was found to inhibit the induction of mitogenesis by TPA (a PKC dependent pathway) and these effects were shown not to be stereospecific. To further investigate the effect of alkylglycerol on cell proliferation, the content of the monoglycerides in ras-transformed cells was analyzed. These cells have lost contact dependent growth arrest indicating a disruption of cell growth regulation. We observed a massive increase in the content of alkylglycerol during the culture of ras transformed cells. This increase is 3 fold higher than MDCK or 3T3 cells. This raises the possibility that alkylglycerol may be the end result of an increased number of cell-cell contacts. We have observed an increase in the accumulation of alkylglycerol in normal and ras-transformed cells. This accumulation is accompanied by a decrease in PKC activity and alkylglycerol was shown to be a potent in vitro inhibitor of PKC. Similarly, alkylglycerol was shown to inhibit PKC $\alpha$ under stimulation by TPA. Alkylgylcerol is a inhibitor of the TPA induced induction of mitogenesis and slows the growth rate of proliferating cultures of 3T3 cells. These results indicate that the endogenous ether-linked glycerolipid, alkylglycerol, is a regulator of cell proliferation through its inhibitory effects on protein kinase C. (Abstract shortened by UMI.)
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Siam, Rania. "Mechanisms of C. crescentus regulation of chromosome replication by a cell cycle regulator protein." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37838.
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Caulobacter crescentus divides asymmetrically to produce two different progeny, a swarmer progeny that is replication incompetent, and a stalked cell progeny that is replication competent. Upon cell division, a cell cycle regulator protein (CtrA) was identified only in the swarmer cells, and additional circumstantial evidence links this protein to being a repressor of chromosome replication. For example, this response regulator protein binds to five specific sites in the replication origin (Cori) designated [a-e]. We carefully studied the binding characteristics of both phosphorylated (CtrA~P) and unphosphorylated forms of the protein to the five binding sites [a-e] in the replication origin (Chapter 2) and upstream of the ctrA gene (Chapter 3). We showed that phosphorylation significantly enhances binding affinity in the replication origin (Chapter 2) but not upstream of ctrA (Chapter 3). In addition a "pseudo-active" protein form (CtrA D51E) that resembles the phosphorylated form in vivo did not improve the binding characteristics (Chapter 3). These results suggest that enhanced binding on phosphorylation is not the only signal achieved on phosphorylation. In fact, CtrA half-site mutation binding studies shows that phosphorylation stimulates protein/protein interaction and cooperative binding between sites [a] and [b] in the replication origin (Chapter 2). We show that CtrA binding site [b] is the major contributor in the cooperative CtrA binding between [a] and [b] (Chapter 4). We demonstrate that cooperative binding of CtrA~P to sites [a] and [b] repress transcription from a strong promoter (Ps), which in turn blocks plasmid replication. In addition, mutating site [b] to block CtrA binding to [a] and [b] has a deleterious effect on chromosome replication (Chapter 4).This cooperative CtrA binding at [a] and [b] is independent from the upstream binding sites [c-e] (Chapter 2). CtrA∼P binding in the origin is altered in the presence of the histone-like protein (IHF) that also binds and overlaps CtrA binding site [c] (Chapter 5). In-fact, IHF binds and overlaps binding site [c] (Chapter 5). We propose a replication model in the stalked cell were IHF binding hinders active CtrA binding in the replication origin and regulates cooperative transcription that coincides with replication initiation.
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Halsey, Richard James. "Construction and characterization of chimaeric human immunodefiency virus type 1 subtype C Gag virus-like particles." Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/4269.
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Includes bibliographical references (leaves 114-128).In this study I explored the possibility of making HIV-1 subtype C Pr55gag-based chimaeric virus-like particles (VLPs) as a boost to the HIV-IC multigene DNA vaccine pTHr.grttnC, which encodes a modified Gag-RT-Tat-Nef fusion protein (GRTTN). Furthermore, an attempt was made to produce VLP analogues to the HIV-IA polyepitope DNA vaccine pTHr.HIVA. A range of in-frame fusions with the C-termini of myristylation-competent p6-truncated Gag and native Pr55gag were made to test how the length of polypeptide and its sequence might affect VLP formation and structure.
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Jackson, Andrew R. 1972. "Estrogenic regulation of N-cadherin in the rat testis : an examination using agonists and antagonists of estradiol." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27349.
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Intercellular junctions within the mammalian testes play an important role during spermatogenesis. The cadherins are a superfamily of integral membrane proteins that mediate calcium-dependent cell adhesion and are involved in the formation of intercellular junctions. The cadherin subtype, known as N-cadherin, mediates the interaction between the germ cells and Sertoli cells of the testis. Previous studies have shown that estrogens are able to modulate N-cadherin mRNA levels in the 7-day-old mouse testis.I have examined the estrogen effects on N-cadherin protein levels in the testes of 21-day-old rats. The rats were injected with either 17$ beta$-estradiol, the anti-estrogens Tamoxifen and ICI 182,780, or estradiol in combination with ICI 182,780. Immunoblotting analysis of testicular proteins shows that N-cadherin levels in the 21-day-old rat are stimulated by estrogen. Treatment with anti-estrogens decrease N-cadherin levels. Administration of estrogen was able to overcome the inhibitory effects of anti-estrogen treatment. The results obtained from these studies indicate that the effect of estrogen on testicular N-cadherin levels is mediated through the estrogen receptor. Estrogen receptor levels within the testis are not altered by exogenous estrogen, but can be affected by treatment with anti-estrogen.
These experiments support the hypothesis that estrogens play an important role in spermatogenesis. In addition, the results provide insight into how disruption of testicular estrogen responsiveness can reduce fertility and why chronic anti-estrogen treatment results in disorganization of the seminiferous epithelium.
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Finney, Michael. "The genetics and molecular biology of unc.-86, a C. elegans cell lineage gene." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14628.
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Babbar, Naveen. "Regulation and function of spermidine/spermine N¹ acetyl transferase (SSAT) in colon carcinogenesis." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289966.
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Epidemiological data suggest that non-steroidal anti-inflammatory drugs (NSAIDs) have anti-tumorigenic activities against colorectal cancer. NSAIDs work by inhibiting cyclooxygenases (COX) enzyme. Sulindac, a NSAID prodrug, is metabolized into pharmacologically active sulfide and sulfone derivatives. Microarray analysis was used to detect COX independent effects of sulindac on gene expression in human colorectal cells. Spermidine/spermine N 1-acetyl transferase (SSAT) gene, which encodes a polyamine catabolic enzyme, was one of the genes induced by clinically relevant sulindac sulfone concentrations. Promoter analysis and mutational studies were done to map the sulindac sulfone dependent response sequences in SSAT 5' flanking sequences, which led to the identification of two Peroxisome Proliferator Activated Receptors (PPARs) response elements (PPREs) in the SSAT gene. PPRE-2 is required for the induction of SSAT by sulindac sulfone and is specifically bound by PPARgamma in the Caco-2 cells, while PPRE-1 is not required for the induction of SSAT by sulindac sulfone, but can be bound by both PPARdelta and PPARgamma. Clinically relevant concentrations of sulfone reduced intracellular polyamine levels, inhibited cell growth and induced apoptosis in colon cancer cells. Further, only sulindac sulfone induced apoptosis could be partially rescued by exogenous polyamines. Upon evaluating other NSAIDs for their action on SSAT gene expression, it was found that they induce SSAT mRNA in either a COX dependent or independent mechanism in colon cancer cells. Studies with physiologically relevant concentrations of aspirin show that these concentrations can induce SSAT expression thereby leading to a decrease in polyamine levels. Activating mutations in K-ras, which is a late process in colon carcinogenesis, led to the suppression of SSAT expression in the Caco-2 cells due to the inhibition of PPARgamma by ERK. K-ras didn't have any effect on the induction of SSAT by sulindac sulfone but partially abolished the apoptosis caused by sulindac sulfone, indicating a possible role of mutant K-ras in sulindac resistant colon polyps. Sulindac sulfone, or Exisulin(TM) have been recently used in clinical trials for the prevention of colon, lung and prostate cancer. The data shown here, suggest that one of the mechanisms, by which sulindac sulfone could act as a chemopreventive agent is to induce the expression of SSAT thereby leading to a decrease in the intracellular polyamines. This reduction in polyamines plays an important part in the apoptosis induced by sulindac sulfone in the colon cancer cells. Further, induction of SSAT seems to a general mechanism for different NSAIDs like aspirin, indomethacin, ibuprofen, sulindac and celecoxib in colon cancer. Aspirin is able to induce SSAT and decrease intracellular polyamines at physiological concentrations, which can lead to a significant reduction in adenoma recurrence. Also, activated K- ras suppressed SSAT, but was not able to abolish the induction of SSAT by sulindac sulfone indicating the potential of using sulindac sulfone in colon cancer chemoprevention.
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Carson, Christine. "Characterization of lamins A and C expression during differentiation of HL-60 cells towards monocytes/macrophages in vitro." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/9718.
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The inducible human promyelocytic cell line HL-60 is known to express a limited complement of intermediate filament proteins (IFPs). In the undifferentiated state these cells express B-type nuclear lamins, but lack lamins A and C and the cytoplasmic IFP vimentin (Paulin-Levasseur et al., 1988). In the present study, the HL-60 cell system was used to determine whether expression of lamins A and C was associated with the differentiated phenotype. HL-60 were treated with two different inducers of monocyte/macrophage differentiation: vitamin $\rm D\sb3$ and TPA. A detailed kinetic analysis of lamins A and C protein expression throughout the differentiation period was made using immunofluorescence microscopy (IFM). The expression of vimentin, the monocyte marker 63D3 and transferrin receptor (TR) were assessed in like manner. HL-60 proliferation was monitored by cell counts, $\sp3$H-thymidineincorporation and cell cycle analysis. Induction of HL-60 cell differentiation by vitamin $\rm D\sb3$ did not lead to expression of either lamins A/C or vimentin. Treatment with TPA, on the other hand, resulted in expression of these proteins in the vast majority of cells within 24 hours. Examination of marker expression and proliferation confirmed that both vitamin $\rm D\sb3$ and TPA induced differentiation in the treated cells. However, exposure to the vitamin resulted in cells which were monocyte-like, while TPA treatment gave rise to cells that more closely resembled macrophages. Lamins A/C expression was clearly not associated with growth arrest in the vitamin $\rm D\sb3$-treated cells, and was found to follow inhibition of replication in TPA-treated populations. It was determined that lamins A/C expression was not coincident with expression of the differentiated phenotype. These results suggested that lamins A/C expression was a post-differentiation event in the HL-60 cell system. (Abstract shortened by UMI.)
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Hocevar, Barbara Ann. "Characterization of nuclear protein kinase C." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1057177248.
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Vandermeer, Lisa Anne. "Evaluation of c-KIT in ovarian surface epithelial cells and ovarian tumours." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/27067.
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Ovulation is a putative risk factor for ovarian cancer, and may be attributed to proliferating ovarian surface epithelial (OSE) cells interacting with the extracellular matrix (ECM) during ovulatory wound repair. We investigated the effects of ECM and cellular density on OSE cell morphology, proliferation, and expression of c-Kit, a proto-oncogene expressed in 70% of ovarian tumours. Fibrillar collagen I caused significant changes in morphology and proliferation but monomeric ECM had no effect. Normal human ovaries co-expressed KIT, collagen I and fibronectin in 75% of abnormal OSE structures. At increased cellular densities, rat OSE cells expressed increased levels of Kit. Retrovirus-mediated expression of c-Kit in OSE caused a significant increase in proliferation. Additionally, sequence analysis of c-KIT in 21 ovarian tumours revealed no mutations. These results suggest a relationship between KIT and collagen I in OSE and that cellular density in the OSE regulates KIT, which increases cell proliferation and may contribute to transformation.
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Al-Mazidi, Hayfa A. "Unique localization of protein kinase C isozymes in T51B rat liver cells and their role in proliferation and apoptosis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq20987.pdf.
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Ilbay, Orkan. "Robustness Mechanisms of Temporal Cell-Fate Progression in C. Elegans." eScholarship@UMMS, 2019. https://escholarship.umassmed.edu/gsbs_diss/1057.
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Robustness is a ubiquitous property of biological systems, however, underlying mechanisms that help reinforce the optimal phenotypes despite environmental or physiological perturbations are poorly understood.
C. elegans development consists of four larval stages (L1-L4) and well-characterized invariant cell lineages, within which the heterochronic pathway controls the order and timing of cell-fates. Environmental or physiological stress signals can slow or temporarily halt larval stage progression; remarkably, however, temporal cell-fate progression remains unaffected.
We show that two widely conserved signaling pathways, insulin and TGF- β, that regulate C. elegans larval stage progression in response to starvation and crowding, respectively, also regulate a rewiring of the heterochronic pathway so that cell-fates remain temporally anchored to appropriate larval stages. This rewiring is mediated by the nuclear hormone receptor DAF-12, and it involves a shift from the reliance on let-7-family microRNAs to the reliance on LIN-46 for proper downregulation of the transcription factor, Hunchback-like-1 (HBL-1), which promotes L2 cell-fates and opposes L3 cell-fates. LIN-46 (which is a homolog of bacterial molybdopterin molybdenum transferase (moeA) and human gephyrin) post-translationally inhibits HBL-1 activity. LIN-46 expression is repressed by the RNA-binding protein LIN-28 at the early stages to permit HBL-1 activity and hence the proper execution of L2 cell-fates.
Our results indicate that robustness mechanisms of temporal cell-fate progression in C. elegans involves 1) coordinated regulation of temporal cell-fates and larval stage progression and 2) collaboration between translational regulation exerted by microRNAs and post-translational regulation exerted by LIN-46 to coordinate HBL-1 downregulation with stage progression.
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Tebo, Julie M. "Characterization of the C-reactive protein receptor on the human monocytic cell line U-937 /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487681788253375.
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Grönberg, Naima. "Induction of pathogenesis-related genes, PR-17a and N-methyltransferase, in barley infested by the aphid Rhopalosiphum padi." Thesis, Södertörn University College, School of Life Sciences, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-656.
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Plants produce a large diverse array of organic compounds that may function in protection against pathogens. Diverse antifungal compounds were reported to exist in barley (Hordeum vulgare L.); the indole alkaloid, gramine, and the pathogenesis-related proteins are some of them. Both the N-methyltransferase that is involved in gramine biosynthesis and PR-17a were studied in barley upon infestation by the bird cherry-oat aphid (Rhopalosiphum padi).
The effect of infestation by R. padi on induction of PR-17a and N-methyltransferase was investigated in different barley lines, susceptible and resistant.
The gene expression of PR-17a was down-regulated in the susceptible cv. Golf and to some extent up-regulated at the first days in var. Lina and then down-regulated. The PR-17a was induced by the aphid infestation in the resistant line CI16145; the gene expression was stronger in the infested plants than in the controls. The different responses in resistant and susceptible lines indicate that the induced PR-17a may play a role in the resistance against aphid infestation. PR-17a was up-regulated systemically in the base in barley after infestation by R. padi.
In the susceptible varieties Lina and Golf, the accumulation of N-methyltransferase did not increase with time from 1 day to 7 days after infestation, as determined by western blots with antibody raised against NMT from barley. The NMT-gene was down-regulated after 7 days infestation in both variety Lina and Golf both locally in the first leaf and in the base. Barley line CI16145 had no accumulation of NMT as was seen by western blotting. There was no induction of NMT in barley upon aphid infestation.
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Bandawe, Gama. "Expression of HIV-1 subtype C nef in E. coli and Nicotiana benthamiana : development of plant-based vaccines for HIV." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/4242.
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Bibliography: leaves 126-145.Expression of the nefgene from HIV-1 subtype C in Nicotiana benthamiana was carried out using a TMV -based vector with the aim of developing a plant-based candidate vaccine for HIV-1. The nef gene of the DU151 isolate of mV-l subtype C taken from a recently seroconverted individual was amplified by PCR with a deletion of 59 amino acids from the cytotoxic N-terminal. The amplified gene was inserted into a bacterial expression vector pProEXHTb for rapid expression of Nef protein, which was used as a diagnostic tool in the development of an indirect ELISA assay for detection of Nef in Nicotiana benthamiana. An indirect ELISA assay was developed using a commercially available polyclonal anti Nef antiserum raised in sheep. The role of codon optimization in expression of Nef in benthamiana was investigated. A synthetic nef gene was constructed based on the codon usage of benthamiana. The plant codon optimized gene and the wild type nef genes were inserted into the TMV -based vector pBSG1057. RNA transcripts from both constructs were used to infect young benthamiana plants. Expression of nefmRNA was confirmed by RT -PCR analysis of total RNA extracted from plants inoculated with respective constructs. The Nef protein was expressed at low levels which were detectable by ELISA. Nef was detectable by Western blot after concentration of plant extract using a membrane filter device. Quantitative analysis of Nef expression in plants was done by western blot on concentrated plant extract from three separate infections. Codon optimization of the nef gene improved the expression of Nef by a factor of about two.
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Keszthelyi, Eniko Judith. "The effects of hormones, growth factors and cyclic AMP on ovarian carcinoma cell proliferation and expression of c-kit and Kit ligand." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0001/MQ36707.pdf.
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Yuan, Libin. "A stretch of 17 amino acids in the prosaposin C-terminus is critical for its binding to sortilin and targeting to lysosomes." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92262.
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Newly synthesized soluble lysosomal proteins are transported from the Golgi apparatus to the lysosomes by two mannose 6-phosphate receptors. However, the sphingolipid activator protein prosaposin is targeted by the alternative trafficking receptor, sortilin. Prosaposin is the precursor of four lysosomal saposins required for the hydrolysis of sphingolipids. A previous study demonstrated that the removal of its C-terminus abolished the trafficking of prosaposin to the lysosomes.To identify the sequences and amino acids involved in the interaction of prosaposin to sortilin and its transport to the lysosomes, we generated six prosaposin deletion constructs and examined the effect of truncation by co-immunoprecipitation and confocal microscopy. The experiments revealed that a 17 amino acid stretch in the first half of the C-terminus (aa524-540) was necessary for the binding of prosaposin to sortilin and essential for its transport to the lysosomes.
Since the pH is able to induce conformational changes in the four saposin domains, we performed a pH-dependent binding assay to test whether or not the binding of prosaposin to sortilin was affected by different pHs. The experiments demonstrated that binding of prosaposin to sortilin occurred at 6.0 or higher. A substantial decrease in binding was detected at pH 5.5, and at pH 5.0 both proteins did not form complexes. This result indicated that the binding of prosaposin to sortilin is pH-dependent.
Since hydrophilic residues usually modulate pH-dependent protein interactions we introduced six site-directed point mutations in hydrophilic residues within the first half of the C-terminus. The results showed that the mutation of single hydrophilic amino acids did not affect the binding of prosaposin to sortilin.
Considering that tryptophan, cysteine and proline residues are important in protein structure and function, we also introduced eight site-directed point mutations to these residues within the 17 amino acid stretch in the C-terminus. The experiments revealed that two tryptophans (W530 and W535), and two cysteines (C528 and C536) were essential for the transport of prosaposin to the lysosomes. In addition, one proline residue (P532) was critical for the proper folding of prosaposin during its synthesis, which was demonstrated by the MG132 Proteasome Inhibition Assay.
In conclusion, we have narrowed down the sortilin recognition site on the prosaposin molecule to a specific 17-residue stretch in the first half of the C-terminus and discovered the essential residues in this region for the lysosomal trafficking of prosaposin.
Les protéines lysosomiales solubles récemment identifiées et synthétisées sont transférées de l'appareil de Golgi des cellules vers les lysosomes par deux récepteurs, des mannoses 6-phosphates. Cependant l'activateur sphingolipidique de la prosaposine est ciblé sur la lysosomes par un récepteur alternatif, la sortiline. La prosaposine est le précurseur de quatre saposines lysosomiales requises pour l'hydrolyse des sphingolipides. Une étude récente a déjà démontré que l'élimination de la terminaison-C de la sphingolipide empêche le transport de la prosaposine vers les lysosomes.
Pour identifier les séquences d'acides aminés impliqués dans l'interaction de la prosaposine avec la sortiline et ainsi clarifier le mode de transport de ces séquences vers les lysosomes, nous avons procédé, par co-immunoprécipitation et immunomicroscopie confocale et à l'élimination de six séquences distinctes de la saposine. Ces expériences ont montré que la première moitié de la terminaison-C (aa524-540) la séquence des 17 résidus peptidiques est nécessaire pour permettre la liaison de la sortiline à la prosaposine et le transport de la prosaposine vers les lysosomes. fr
Le pH du milieu agit sur l'interaction d'un ligand à son récepteur. Nous avons donc analysé la liaison de la prosaposine à la sortiline à différents pH. Les résultats on montré que la liaison de la prosaposine à la sortiline se fait à un pH de 6.0 ou plus. Par contre la prosaposine ne forme pas de complexes avec la sortiline à des pH de 5.0 et 5.5. fr
Puisque les résidus hydrophiles modulent normalement l'interaction des protéines nous avons introduit des mutations focales (point mutations) sur six sites de tels résidus hydrophiles de la terminaison-C de la prosaposine. Les résultats ont montré que de telles mutations n'ont aucun effet sur la liaison de la sortiline à la prosaposine. fr
Considérant que le tryptophane, la cystéine et la proline forment des séquences importantes de la structure et de la fonction des protéines, nous avons inséré huit mutations focales additionnelles sur la séquence de 17 résidus de la terminaison-C de la prosaposine. Les résultats ont révélé que deux molécules de tryptophane (W530 etW535) et deux molécules de cystéine (C528 et C536) sont essentielles au transport de la prosaposine vers les lysosomes. Par ailleurs, une molécule de proline (P532) provoque la dégradation de la prosaposine par des protéosomes. fr
En conclusion nous avons circonscrit certains aspects moléculaires de la relation de la sortiline à la prosaposine. Nous avons montré en particulier que la liaison de la sortiline à la prosaposine se situe au niveau d'un site précis du segment de la terminaison-C de la prosaposine dont certains éléments jouent un rôle essentiel dans le transport de la prosaposine vers les lysosomes. fr
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Wang, Haizhen. "The C-Phycocyanin/Beta Protein Inhibits Cancer Cell Proliferation." unrestricted, 2008. http://etd.gsu.edu/theses/available/etd-04212008-155113/.
Full textAbstract:
Thesis (M.S.)--Georgia State University, 2008.Title from file title page. Zhi-Ren Liu, committee chair; Delon W. Barfuss, Jenny J. Yang, committee members. Electronic text (69 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed June 11, 2008. Includes bibliographical references (p. 61-67).
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Fearon, Shelley Helen. "The Development of an African Horse Sickness Virus VP7 Quasi-Crystal Vaccine Candidate in N. benthamiana." Master's thesis, Faculty of Science, 2019. https://hdl.handle.net/11427/31671.
Full textAbstract:
African horse sickness (AHS) is a debilitating viral disease affecting equines and has resulted in many disastrous epizootics. To date, no successful therapeutic treatment exists for AHS and the commercially used live-attenuated vaccines (LAVs) have various side effects. Insoluble particulates have been shown to increase immunogenicity when compared to soluble subunit vaccines and previous studies demonstrated protection of BALB/c mice immunised with African horse sickness virus (AHSV) VP7 against a lethal challenge of AHSV-7 (Bailey 2016; Rutkowska et al. 2011; St Clair et al. 1999; Storni et al. 2005; Wade-Evans et al. 1997). This study investigates a safer monovalent vaccine alternative based on plant-produced quasicrystals of the serogroup-specific AHSV structural protein, VP7. AHSV serotype 5 (AHSV-5) VP7 was expressed in Nicotiana benthamiana by means of Agrobacterium-mediated infiltration of plant expression vector pRIC3.0 encoding VP7 and quasi-crystals purified by means of density gradient ultracentrifugation. The presence of AHSV VP7 quasi-crystals was confirmed by western immunoblotting with anti-AHSV VLP guinea-pig serum and characterized using transmission electron microscopy. After optimizing the purification protocol and achieving satisfactory concentrations, AHSV-5 VP7 quasi-crystals were used in guinea-pig immunogenicity studies where the experimental group (n=5) was inoculated with prime- and boostinoculations of between 10 and 50 µg of purified AHSV VP7 quasi-crystals, and the control group (n=5) inoculated with a control inoculum prepared in the identical manner as the vaccine but using a pRIC3.0 expression vector lacking VP7. Western immunoblot analysis of the humoral response showed stimulation of very high titres of anti-VP7 antibodies 28 days after the boost-inoculation. In addition, RNA-seq transcriptome profiling of guinea-pig spleen derived RNA was used to investigate the global immune response to AHSV-5 VP7 quasi-crystals. Thirty genes involved in innate and adaptive immunity were found to be significantly differentially expressed (q≤0.05) in experimental transcriptome data when compared to the control. Differential expression of genes involved in T-helper (Th)1, Th2 and Th17 cell differentiation and the T-cell receptor signalling pathway suggest a possible cell-mediated immune response to AHSV-5 VP7 quasi-crystals. Upregulation of several important cytokines and cytokine receptors were noted in response to VP7 quasi-crystals e.g. TNFSF14, CX3CR1, IFNLR1 and IL17RA. TNFSF14 and CX3CR1 play a role in T-cell proliferation and cytotoxic T-cell responses respectively. And IFNLR1 and IL17RA are key cytokines in antiviral defences. Upregulation of IL17RA suggests a Th17 response which has been reported as a key component in AHSV immunity. To the best of our knowledge, this study is the first to report the expression of plantproduced AHSV VP7 quasi-crystals and the first time that the cell-mediated immune response to these particles has been assessed. While further investigation is needed, these results suggest that AHSV-5 VP7 quasi-crystals produced in N. benthamiana are immunogenic, inducing both humoral and cell-mediated responses.
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Jannie, Karry Marie. "Activated leukocyte cell adhesion molecule (ALCAM) regulation of tumor cell behavior and neuronal targeting." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/2901.
Full textAbstract:
Numerous events during development require the tightly controlled and regulated interaction of cells - from gastrulation in the early embryo to axonal pathfinding and remodeling of synaptic networks. Each of these events is dependent upon signals generated by cell-cell interactions, which are in turn specified by a diverse number of cell adhesion molecules. Many families of cell adhesion molecules have been described, and these fall into the broad categories of cadherins, immunoglobulin superfamily (IgSF) members, selectins, and integrins. Activated Leukocyte Cell Adhesion Molecule (ALCAM) is a member of the IgSF, and controls numerous developmental processes, ranging from hematopoiesis to neuronal targeting. Furthermore, this protein has been implicated in the progression of numerous cancers of diverse origins. Despite the variety of developmental and pathological processes in which ALCAM has been implicated, little is known about how it signals in the cell - few extracellular binding partners have been isolated, and, as of this writing, no cytoplasmic interactors have been identified. The purpose of the work presented in this thesis was to elucidate the mechanisms by which ALCAM influences cell behavior, specifically in uveal melanoma cells, and to determine novel extra- and intracellular ligands. Here, I report the regulation of cadherin-based junctions by ALCAM in uveal melanoma cells, as well as provide evidence for a novel extracellular interaction with L1 cell adhesion molecule, and identify three novel intracellular binding partners.
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Prevost, Manon. "The effects of stromal-derived factors and gonadotropins on rat ovarian surface epithelial cell proliferation and expression of c-Kit and Kit ligand." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6452.
Full textAbstract:
Although ovarian cancer is rare, it is the most deadly of gynaecological cancers. Unfortunately, still very little is known about the cells that give rise to 90% of ovarian cancers, the ovarian surface epithelial (OSE) cells, and much of the available data remains controversial. This project was designed to address the possible involvement of ovarian stromal/thecal cells in the regulation of OSE cell growth and Kit and KL expression. Such interactions are probably involved in normal OSE-stromal/thecal cell activities as well as in interactions occurring within inclusion cysts and leading to ovarian tumour formation. The regulation of rat OSE (ROSE) cell growth by theca-derived factors and gonadotropins was investigated by proliferation experiments and cell counts. The modulation of Kit and Kit ligand (KL) messenger ribonucleic acid (mRNA) expression in these cells by the same factors was investigated by Northern blot analysis and reverse transcription-polymerase chain reaction (RT-PCR). (Abstract shortened by UMI.)