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1
Islam, Azharul. "Cell-walls of growing plant cells." Thesis, University of Westminster, 2013. https://westminsterresearch.westminster.ac.uk/item/8z033/cell-walls-of-growing-plant-cells.
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The plant primary cell wall is a three-dimensional interwoven network of cellulose microfibrils, cross-linked by xyloglucan and dispersed in a pectin matrix. It has been suggested that in the wall of growing plant cells, xyloglucan is bound to the rigid cellulose microfibrils by hydrogen bonds and holds the microfibrils together by forming molecular tethers, which is referred to as the ‘sticky network’ model. Plant growth occurs when these tethers are peeled from the microfibrils by expansins or broken by glycosidases or transglycosylases. A number of researchers have presented theoretical difficulties and observations inconsistent with this model and a new hypothesis has been proposed, claiming that the cellulose – xyloglucan cross-links may act as ‘scaffolds’ holding the microfibrils apart. Analogies with synthetic polymers suggests that the spacing between the cellulose microfibrils may be an important determinant of the mechanical properties of the cell wall and the results presented in this thesis support this hypothesis. Water contents of Acetobacter xylinus synthesized cellulose based cell wall analogues (as a mimic of primary cell wall) and sunflower hypocotyl cell walls were altered using high molecular weight polyethylene glycol (PEG) solution, and their extension under a constant load was measured using a creep extensiometer and showed that there were clear reduction (30-35%) in extensibility suggesting that water content of the wall and therefore the cell wall free volume directly influence wall extensibility. When hydration of A. xylinus cellulose composite pellicles was reduced using PEG 6000 solution and re-hydrated in buffer solution, followed by treatment with α-expansin or snail acetone powder extract, it was found that expansin and snail powder extracts caused a rapid rehydration of the composites and that the pellicles only returned to their original weights after these treatments, suggesting that expansin and snail powder can increase the free volume of the wall perhaps contributing to the increases in extensibility that they cause. Assays on cell wall fragments also indicated that expansin increased the cell wall free volume, demonstrated by changes of the turbidity of fragment suspensions. The role of pectic polysaccharide, RG-II, in cell wall biomechanics was also investigated using mechanical and biochemical testing of available Arabidopsis thaliana cell wall mutants and by incorporating RG-II (purified from red wine) with Acetobacter cellulose. It was demonstrated that RG-II significantly increased the hydration of cellulose composite; hydration rate was 15 -16% more than the composite without RG-II and thus increased the pellicle extensibility. From the results, it is evidenced that cell wall extension is not only the consequences of breaking hydrogen bonds between cellulose microfibrils and xyloglucan by expansins or glycosidases and transglycosylases, but also a wider range of factors are involved including cell wall water content, cell wall free volume and the pectic polymers, especially RG-II.
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Mittal, Nikhil 1979. "Cell-cell and cell-medium interactions in the growth of mouse embryonic stem cells." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62602.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 100-108).
Embryonic stem cells serve as powerful models for the study of development and disease and hold enormous potential for future therapeutics. Due to the potential for embryonic stem cells (ESCs) to provide a variety of tissues for use in regenerative medicine, there has been great interest in the identification of factors that govern the differentiation of ESCs into specific lineages. Much of this research builds on previous studies of the role of intercellular signaling in the specification of various cell types in the developing embryo. However, relatively little work has been done on understanding the role of cell-cell communication in the self-renewal of ESCs. In the first part of this thesis I describe the development and testing of new devices for studying intercellular signaling - the nDEP microwell array and the Bio Flip Chip (BFC). We used the BFC to show that cell-cell interaction improves the colony-forming efficiency and the self-renewal of mouse ESCs. Further, we demonstrate that the interaction is at least partly diffusible. In the next part of the thesis I describe our use of more traditional assays to validate the results obtained using the BFC and to further explore the role of diffusible signaling in the survival of mouse ESCs. We demonstrate the existence of an optimal density for 2-day culture of mouse ESCs. Further, we demonstrate that the increase in growth with plating density (103-104 cells/cm2) is at least partly due to the existence of one or more survival-enhancing autocrine factor(s) in mouse ESC cultures, and that one of these factors is Cyclophilin A. Finally, we demonstrate that changes in the low molecular weight composition of the medium are likely responsible for the decrease in growth at high plating densities (>104 cells/cm2). We use a numerical model to show that competition between the positive effect (on growth) of autocrine survival factors and the negative effect of nutrient depletion can account for the observed optimal growth density. Our study provides new insight into the processes underlying, and optimization of, growth in cell types that lack contact inhibition such as cancer cells and stem cells.
by Nikhil V. Mittal.
Ph.D.
3
Pat, Sze Wa. "Cell metabolism in cell death and cell growth." HKBU Institutional Repository, 2007. http://repository.hkbu.edu.hk/etd_ra/775.
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Rabodzey, Aleksandr. "Flow-induced mechanotransduction in cell-cell junctions of endothelial cells." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/41586.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2006.Includes bibliographical references (leaves 86-92).
Endothelial cells show an unexpected behavior shortly after the onset of laminar flow: their crawling speed decreases ~40% within the first 30 min, but only in a confluent monolayer of endothelial cells, not in subconfluent cultures, where cell-cell interactions are limited. This led us to study early shear effects on cell-cell adherens junctions. We found a 30±6% increase in the number of VE-cadherin molecules in the junctions. The strength of interactions of endothelial cells with surfaces coated with recombinant VE-cadherin protein also increased after laminar flow. These observations suggest that endothelial cell junction proteins respond to flow onset. The process of clustering may induce diffusion of monomers to the junction area, resulting in an overall increase in VE-cadherins in the junctions. To directly confirm the role of adherens junctions in the decrease in cell crawling speed, we used siRNA-knockdown technique to produce cells lacking VE-cadherin. These cells showed no decline in crawling speed under flow. Our interpretation is consistent with previous data on junction disassembly 8 hr after flow onset. The speed of endothelial cell crawling returns to the original level by that time, and junctional disassembly may explain that phenomenon. In order to understand better the change in VE-cadherin distribution under flow and during junction formation and remodelling, we developed a mathematical model of VE-cadherin redistribution in endothelial cells. This model allowed us to develop a quantitative framework for analysis of VE-cadherin redistribution and estimate the amount of protein in the junctions and on the apical surface. In addition to that, the model explains rapid junction disassembly in the leukocyte transmigration and junction formation in subconfluent cells.
(cont.) These studies show that intercellular adhesion molecules are important in the force transmission and shear stress response. Their role, however, is not limited to flow mechanotransduction. Intercellular force transmission has an important application - organ development and, specifically, angiogenesis. We studied the role of VE-cadherin in vessel development in HUVECs and showed that VE-cadherin-null cells do not form vessels in the in vitro assay. This observation confirms the important role of intercellular force transmission in response to external force caused by flow or exerted by other cells.
by Aleksandr Rabodzey.
Ph.D.
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Sarvi, Sana. "Small cell lung cancer and cancer stem cell-like cells." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9542.
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Small cell lung cancer (SCLC) is a highly aggressive malignancy with extreme mortality and morbidity. Although initially chemo- and radio-sensitive, almost inevitable recurrence and resistance occurs. SCLC patients often present with metastases, making surgery not feasible. Current therapies, rationally designed on underlying pathogenesis, produce in vitro results, however, these have failed to translate into satisfactory clinical outcomes. Recently, research into cancer stem cells (CSCs) has gained momentum and form an attractive target for novel therapies. Based on this concept, CSCs are the cause of neoplastic tissue development that are inherently resistant to chemotherapy, explaining why conventional therapies can shrink the tumour but are unable to eliminate the tumour completely, leading to eventual recurrence. Here I demonstrate that SCLC H345 and H69 cell lines contain a subset of cells expressing CD133, a known CSC marker. CD133+ SCLC sub-population maintained their stem cell-like phenotype over a prolonged period of culture, differentiated in appropriate conditions and expressed the embryonic stem cell marker Oct-4 indicating their stem-like phenotype. Additionally, these cells displayed augmented clonogenic efficacy, were chemoresistant and tumorigenic in vivo, distinct from the CD133- cells. Thus, the SCLC CD133 expressing cells fulfil most criteria of CSClike definition. The molecular mechanisms associated with CD133+ SCLC chemoresistance and growth is unknown. Up-regulated Akt activity, a known promoter of resistance with survival advantage, was observed in CD133+ SCLC cells. Likewise, these cells demonstrated elevated expression of Bcl-2, an anti-apoptotic protein compared to their negative counterpart explaining CD133+ cell chemoresistance phenotype. Additionally, CD133+ cells revealed greater expression of neuropeptide receptors, gastrin releasing peptide (GRP) and V1A receptors compared to the CD133- cells. Addition of exogenous GRP and arginine vasopressin (AVP) to CD133+ SCLC cells promoted their clonogenic growth in semi-solid medium, illustrating for the first time neuropeptide dependent growth of these cells. A novel peptide (peptide-1) was designed based on the known structure of the substance P analogues that have shown benefit in animal models and in early clinical trials. This compound inhibited the growth of SCLC cells in in vitro with improved potency and stability compared to previous analogues and reduced tumorigenicity in vivo. Interestingly, peptide-1 was more effective in CD133+ cells due to increased expression of neuropeptide receptors on these cells. In conclusion, my results show that SCLC cells retain a sub-population of cells that demonstrate CSC-like phenotype. Preferential activation of Akt and Bcl-2 survival pathways and enhanced expression of neuropeptide receptors contribute to CD133+ SCLC chemoresistance and growth. Therefore, it can be proposed that CD133+ cells are the possible cause of SCLC development, treatment resistance and disease recurrence. Despite being chemoresistant, CD133+ cells demonstrated sensitivity to peptide-1. The identification of such new analogue that demonstrates efficacy towards resistant CD133+ SCLC cells is a very exciting step forward in the identification of a potential new therapy for resistant disease.
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Wong, Ching-hang. "Cell-cell interactions and cell junction dynamics in the mammalian testis." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31993084.
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Chowdhury, Azazul Islam. "Role of Cell-cell Interactions and Palmitate on β-cells Function." Doctoral thesis, Uppsala universitet, Institutionen för medicinsk cellbiologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-230841.
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The islets of Langerhans secrets insulin in response to fluctuations of blood glucose level and efficient secretion requires extensive intra-islet communication. Secretory failure from islets is one of the hallmark in progression of type 2 diabetes. Changes in islet structure and high levels of saturated free fatty acids may contribute to this failure. The aim of this thesis is to study the role of cell-cell interactions and palmitate on β-cells functions. To address the role of cell-cell interactions on β-cells functions MIN6 cells were cultured as monolayers and as pseudoislets. Glucose stimulated insulin secretion was higher in pseudoislets compared to monolayers. Transcript levels of mitochondrial metabolism as well glucose oxidation rate was higher in pseudoislets. Insulin receptor substrate-1 (IRS-1) phosphorylation was altered when cells were grown as pseudoislets. Proteins expression levels related to glycolysis, cellular connections and translational regulations were up-regulated in pseudoislets. We propose the superior capacity of pseudoislets compared to monolayers depend on metabolism, cell coupling, gene translation, protein turnover and differential IRS-1 phosphorylation. To address the role of palmitate on β-cells human islets were cultured in palmitate. Long term palmitate treatment decreased insulin secretion which is associated with up-regulation of suppressor of cytokine signaling-2 (SOCS2) and protein inhibitor of activated STAT-1 (PIAS1). Up-regulation of SOCS2 decreased phosphorylation of Akt at site T308, whereas PIAS1 decreased protein level of ATP- citrate lyase (ACLY) and ATP synthase subunit B (ATP5B). We propose long term palmitate treatment reduces phosphatidylinositol 3-kinase (PI3K) activity, attenuates formation of acetyl-CoA and decreases ATP synthesis which may aggravate β-cells dysfunction.
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Wang, Wei. "Modulation of immune cell responses by small cell lung cancer cells." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/modulation-of-immune-cell-responses-by-small-cell-lung-cancer-cells(7bdc85c2-acd8-4f13-9d2b-e2ce07d1567b).html.
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Small Cell Lung Cancer (SCLC) accounts for 15-20% of all lung cancers and kills at least one person every 2 hours in the UK. There is no effective treatment and overall 2-year survival is less than 5%. Patients with SCLC have poorly understood local and systemic immune defects. Previous studies have shown several important defects in cell-mediated immune responses in patients with SCLC. A better understanding of interactions between SCLC tumour cells and immune cells may lead to the development of novel therapeutic approaches. There is increasing recognition that immunological biomarkers may add to traditional histological analyses and can be exploited in the management of multiple epithelial malignancies. There are currently no such markers used in the management of SCLC. In my PhD project, I have shown that cell lines from different SCLC patients have differential immunosuppressive capabilities. These properties are mediated by the secretion of differing levels of soluble molecules that can suppress the mixed leukocyte reaction (MLR) and CD4+ T cell proliferation, induce IL-10 secretion and differentiation of functional CD4+CD25+CD127+FoxP3+Helios- regulatory T cells (Tregs) from naïve CD4+ T cells. IL-15 is secreted by SCLC cells in culture in proportion to their immunosuppressive capability. Its in vivo relevance is supported by its presence in tumour biopsy samples. The suppressive effect on CD4+ T cell proliferation and the induction of Treg cell population was not affected by blocking IL-10 or TGF-β signalling but was partially reversed by blocking IL-15 activity. Therefore, IL-15 is one, though not the only, soluble molecule produced by SCLC cells to mediate immune suppression by inducing increased population of Treg cells. This may represent a mechanism by which SCLC cells can suppress the immune response. In addition, SCLC cells supressed TNF-α release from monocytes in response to LPS stimulation, down-regulated expression of CD16 and CD86 and upregulated expression of CD163 and CD206 on monocyte-derived macrophages (MDMs) upon activation. This M2-like phenotype poralization was associated with decreased TNF-α and IL-6 production and increased IL-10 secretion. These effects were abrogated by blocking the signalling of bombesin-like peptides (BLPs) that are neuropeptides produced by SCLC cells using a GRP receptor (GRP-R) antagonist. Therefore, the polarization of macrophages to an M2-like phenotype by SCLC cell-derived BLPs may represent another mechanism by which SCLC tumours suppress the immune response. Finally, SCLC tumour biopsies were shown to be infiltrated with various mononuclear immune cells and Treg cells. CD45 and FoxP3 were used as paninflammatory cell and Treg cell markers respectively. An elevated CD45+ infiltrate was predictive of prolonged survival in SCLC independent of age, sex, stage or treatment strategy. An elevated FoxP3+/CD45+ ratio was predictive of a significantly worse prognosis. This study identifies potential mechanisms by which SCLC tumour cells may downregulate local and systemic immune response, and also identifies an independent prognostic marker to predict patient survival in SCLC. Further, IL- 15 and BLPs are potential novel therapeutic targets in SCLC.
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Wong, Ching-hang, and 黃政珩. "Cell-cell interactions and cell junction dynamics in the mammalian testis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31993084.
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Sampangi, Sandeep. "Autologous human kidney proximal tubule epithelial cells (PTEC) modulate dendritic cell (DC), T cell and B cell responses." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/82033/1/Sandeep_Sampangi_Thesis.pdf.
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This is a comprehensive study of human kidney proximal tubular epithelial cells (PTEC) which are known to respond to and mediate the pathological process of a range of kidney diseases. It identifies various molecules expressed by PTEC and how these molecules participate in down-regulating the inflammatory process, thereby highlighting the clinical potential of these molecules to treat various kidney diseases. In the disease state, PTEC gain the ability to regulate the immune cell responses present within the interstitium. This down-regulation is a complex interaction of contact dependent/independent mechanisms involving various immuno-regulatory molecules including PD-L1, sHLA-G and IDO. The overall outcome of this down-regulation is suppressed DC maturation, decreased number of antibody producing B cells and low T cell responses. These manifestations within a clinical setting are expected to dampen the ongoing inflammation, preventing the damage caused to the kidney tissue.
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Ortmann, Daniel. "Reporter cell lines to study cell populations and fate decisions during human pluripotent stem cell differentiation in vitro." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648356.
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Carnathan, Diane Gail Vilen Barbara J. "Dendritic cell regulation of B cells." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,1200.
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Thesis (M.S.)--University of North Carolina at Chapel Hill, 2007.Title from electronic title page (viewed Mar. 26, 2008). "... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Microbiology and Immunology, School of Medicine." Discipline: Microbiology and Immunology; Department/School: Medicine.
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Iqbal, Syed Amir. "Asymmetric Cell Division in Mammalian Cells." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503635.
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Cadart, Clotilde. "Cell size homeostasis in animal cells." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS103/document.
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Le mécanisme d’homéostasie de taille chez les cellules animales est très peu compris actuellement. Cette question est pourtant d’un intérêt majeur car le maintien de l’homéostasie de taille dans une population de cellules prolifératives doit se faire par une coordination entre la croissance et la division. Chez la levure S. pombe, il a ainsi été montré que la taille est une information cruciale pour déclencher l’entrée en mitose (Fantes, 1977). Chez plusieurs bactéries et les cellules filles de la levure S. cerevisiae au contraire, de récentes études ont au contraire montré que l’homéostasie de taille était le résultat d’une addition constante de volume, indépendamment de la taille initiale des cellules (Campos et al., 2014; Soifer et al., 2016; Taheri-Araghi et al., 2015). Ce mécanisme est appelé « adder » et génère une régression des tailles à la moyenne, génération après génération. Ces résultats ont été possibles grâce au développement de techniques permettant la mesure dynamique du volume à l’échelle de la cellule unique et sur plusieurs générations. Une telle mesure est cependant très difficile chez les cellules de mammifère dont le volume fluctue constamment et qui cyclent sur des temps plus longs (environ 20 heures). Pour cette raison, la plupart des approches proposées sont indirectes (Kafri et al., 2013; Sung et al., 2013; Tzur et al., 2009) ou reposent sur une mesure de la masse plutôt que du volume (Mir et al. 2014; Son et al., 2012). Ensemble, ces études ont montré que les cellules de mammifère croissaient de manière exponentielle. Elles ont aussi remis en cause le modèle traditionnel qui proposait que l’homéostasie de taille reposait sur l’adaptation de la durée du cycle et mis en avant un rôle de la régulation de la vitesse de croissance. Cependant, aucun modèle n’a réellement été proposé ou démontré. La nature et l’existence même d’un mécanisme maintenant l’homéostasie de taille des cellules de mammifère est en fait discutée (Lloyd, 2013).Pour caractériser l’homéostasie de taille des cellules de mammifères, nous avons développé une technique permettant pour la première fois la mesure du volume de ces cellules sur des cycles complets (Cadart et al., 2017; Zlotek-Zlotkiewicz et al. 2015). Nous montrons que plusieurs types cellulaires (HT29, MDCK et HeLa) se comportent d’une manière similaire à celle d’un « adder ». Pour tester davantage cette observation, nous induisons artificiellement des divisions asymétriques en confinant les cellules dans des micro-canaux. Nous observons que les asymétries de tailles sont réduites mais pas complètement corrigées au cours du cycle suivant, à la manière d’un « adder ». Pour comprendre comment la croissance et la progression dans le cycle sont coordonnées et génère cet « adder », nous combinons notre méthode de mesure de volume avec un suivi de la progression dans les différentes phases du cycle. Nous montrons que la durée de la phase G1 est inversement corrélée au volume initial des cellules. Cependant, cette corrélation semble contrainte par une durée minimale de G1 mise en évidence lors de l’étude de cellules artificiellement poussées à atteindre de grandes tailles. Néanmoins, même dans cette condition où la modulation de la durée du cycle est perdue, l’observation du « adder » est maintenue. Ceci suggère un rôle complémentaire de la régulation de la vitesse de croissance des cellules. Nous proposons donc une méthode pour estimer théoriquement la contribution relative de l’adaptation de la vitesse de croissance et de la durée du cycle dans le contrôle de la taille. Nous utilisons cette méthode pour proposer un cadre général où comparer le processus homéostatique des bactéries et de nos cellules. En conclusion, notre travail apporte pour la première fois la démonstration que les cellules de mammifères maintiennent l’homéostasie grâce à un mécanisme similaire au « adder ». Ce mécanisme semble impliquer à la fois une modulation de la durée du cycle et du taux de croissanceThe way proliferating mammalian cells maintain a constant size through generations is still unknown. This question is however central because size homeostasis is thought to occur through the coordination of growth and cell cycle progression. In the yeast S. pombe for example, the trigger for cell division is the reach of a target size (Fantes, 1977). This mechanism is referred to as ‘sizer’. The homeostatic behavior of bacteria and daughter cells of the yeast S. cerevisiae on the contrary was recently characterized as an ‘adder’ where all cells grow by the same absolute amount of volume at each cell cycle. This leads to a passive regression towards the mean generation after generation (Campos et al., 2014; Soifer et al., 2016; Taheri-Araghi et al., 2015). These findings were made possible by the development of new technologies enabling direct and dynamic measurement of volume over full cell cycle trajectories. Such measurement is extremely challenging in mammalian cells whose shape constantly fluctuate over time and cycle over 20 hours long periods. Studies therefore privileged indirect approaches (Kafri et al., 2013; Sung et al., 2013; Tzur et al., 2009) or indirect measurement of cell mass rather than cell volume (Mir et al. 2014; Son et al., 2012). These studies showed that cells overall grew exponentially and challenged the classical view that cell cycle duration was adapted to size and instead proposed a role for growth rate regulation. To date however, no clear model was reached. In fact, the nature and even the existence of the size homeostasis behavior of mammalian cells is still debated (Lloyd, 2013).In order to characterize the homeostatic process of mammalian cells, we developed a technique that enable measuring, for the first time, single cell volume over full cell cycle trajectories (Cadart et al., 2017; Zlotek-Zlotkiewicz et al. 2015). We found that several cell types, HT29, HeLa and MDCK cells behaved in an adder-like manner. To further test the existence of homeostasis, we artificially induced asymmetrical divisions through confinement in micro-channels. We observed that asymmetries of sizes were reduced within the following cell cycle through an ‘adder’-like behavior. To then understand how growth and cell cycle progression were coordinated in way that generates the ‘adder’, we combined our volume measurement method with cell cycle tracking. We showed that G1 phase duration is negatively correlated with initial size. This adaptation is however limited by a minimum duration of G1, unraveled by the study of artificially-induced very large cells. Nevertheless, the adder behavior is maintained even in the absence of time modulation, thus suggesting a complementary growth regulatory mechanism. Finally, we propose a method to estimate theoretically the relative contribution of growth and timing modulation in the overall size control and use this framework to compare our results with that of bacteria. Overall, our work provides the first evidence that proliferating mammalian cells behave in an adder-like manner and suggests that both growth and cell cycle duration are involved in size control
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Stewart, Alasdair Gwilym. "Studies of focal adhesion kinase in epithelial cells : involvement in cell-cell adhesion." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1446839/.
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Epithelial cell-cell adhesion is mediated by tight junctions, adherens junctions and desmosomes. Epithelial cell-matrix adhesion is mediated by hemidesmosomes and focal contacts. These complexes exhibit great plasticity, and each contains molecular components which are able to participate in one or more of the other adhesive complexes. Focal adhesion kinase (FAK/pl25FAK) is a non-receptor tyrosine kinase which transduces signals from integrins at sites of focal contact to promote adhesion, spreading and migration. FAK possesses a central kinase domain which is flanked by large, non-catalytic, amino- and carboxy-terminal domains. Whereas the functions of the carboxy-terminal and kinase domains of FAK are well understood, the role of the amino-terminal domain remains unclear. FAK expression was examined in the human epithelial cell line, HEK 293. Amino-terminal FAK immunoreactivity was noted at sites of cell-cell contacts and in the nucleus, in contrast to carboxy-terminal immunoreactivity, which was largely cytoplasmic and perinuclear. Western blot analysis of endogenous FAK revealed expression of a presumptive proteolytic cleavage fragment corresponding to the amino- terminal domain. A series of FAK constructs was generated to test the hypothesis that the observed amino-terminal FAK localisation was due to this proteolytic fragment. Epitope- tagged Amino-Terminal FAK (ATF) constructs localised primarily at areas of cell-cell contact and in the nucleus in HEK 293 cells. This localisation was independent of Tyrosine 397, the major FAK autophosphorylation site. This sub-cellular distribution was confirmed in another epithelial cell line, MDCK, in which transiently transfected ATF constructs also localised primarily to the nucleus and at cell-cell contacts. HEK 293 cells were characterised with respect to expression of adhesive proteins, and ATF was found to co- localise with the tight junction protein occludin, with cortical actin and with junctional ?1 integrin. Immunoprecipitation data suggests that none of these proteins forms a precipitable complex with ATF. These findings indicate that the amino-terminal domain of FAK is capable of localising at epithelial cell-cell contacts and suggest a novel role for FAK in mediating cross-talk between focal contacts and cell-cell contacts through endogenously expressed amino-terminal FAK fragments.
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Sarris, Milka. "Dynamics of helper T cell and regulatory T cell interactions with dendritic cells." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611896.
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ETHIRAJ, SINDUJA. "Cell-Cell Junction Signaling Regulating DNA Double-Strand Break Repair In Breast Cells." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/132.
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Genomic instability and acquisition of invasiveness through the basement membrane extracellular matrix (ECM) are two major processes for epithelial cell malignancy in breast cancer. DNA double-strand break repair (DSBR) is one of the processes that get misregulated during breast cancer progression. In addition, radiation induced breaks such as those induced during radiation therapy to treat breast cancer patients are repaired by DSBR, rendering this pathway relevant for therapy as well. DSBR can occur either by homologous recombination (HR) or non-homologous end-joining (NHEJ). HR is accepted as the more error-free pathway. HR is regulated by the cell cycle status such that an increase is observed in G2/M, whereas NHEJ is observed throughout the cell cycle. Previous data show that ECM signaling regulates HR, as well as the kinetics of ionizing radiation (IR) induced complex formation at break sites, or foci kinetics. Both human breast epithelial cell lines and primary mouse mammary epithelial cells were used to show that the ECM receptor β1-integrin is necessary and sufficient in down regulating HR, as well as IR induced foci formation kinetics for the DSBR proteins RAD51, MRE11, and γ-H2AX in single mammary epithelial cells. RAD51 is required for most HR, whereas MRE11 and γ-H2AX function in HR as well as DNA damage signaling. Interestingly, ECM signaling up-regulates HR in cells that have “correct” in vivo-like cell-cell junctions. Based on the observation that single cells and junctioned cells respond to ECM in exact opposite manner, I hypothesized that ECM signaling may interact with cell-cell junction signaling pathways in regulating DNA repair. To test this hypothesis, I asked whether the main breast epithelial adherens junction cadherin, E-cadherin, is involved. I blocked E-cadherin function using a monoclonal antibody MB2. The function blocking was demonstrated by the loss of cell-cell junction interactions and observation of increased cell scattering using phase microscopy. I then asked whether blocking E-cadherin altered the expression and localization of proteins related to DNA repair. Indirect immuno-fluorescence showed that in the E-cadherin blocked non-tumorigenic breast epithelial cell line HMT-3522 S1 there is an up-regulation of nuclear γ-H2AX and RAD51, as well as an increase in the proliferation marker Ki67. In non-proliferative MB2 blocked cells there is an upregulation of γ-H2AX and reduced Ki67. Furthermore, in these proliferative and non-proliferative blocked cells we were able to see lower levels of β-catenin near the cell membrane and an increase in its levels inside the cell especially in the nucleus. The latter has been confirmed also by western blot technique comparing the nuclear and cytoplasmic fraction expression. In addition, western blots showed that total RAD51 level was down-regulated by E-cadherin blocking and γ-H2AX levels were found to be higher in proliferative and non-proliferative MB2 treated cells. MB2 treated cells have a higher frequency of HR in the absence of ECM and in the presence of ECM, MB2 blocking abolishes the ECM effect on HR. Furthermore, in the absence of ECM, RAD51 siRNA treated cells down-regulated HR but the absence of RAD51 did not down regulate HR in the presence of ECM. I was not able to see any difference in the phosphorylated forms of β-catenin such as Tyr-142, Ser-45 and Tyr-86 that has the ability to enter into the nucleus. Therefore, E-cadherin was found to block nuclear β-catenin, RAD51 and γ-H2AX in a proliferation-independent manner. E-cadherin also was necessary for ECM to up-regulate HR. The up-regulation of HR by ECM was only slightly dependent on RAD51 suggesting a novel E-cadherin-dependent and RAD51-independent HR component in breast epithelial cells in contact with ECM as they are in vivo in the normal breast tissue. These experiments will help us to understand the role of E-cadherin and β-catenin in DNA double-stand break repair directly, as well as in combination with ECM signaling. Both alterations in integrin mediated signaling and cell-cell junction integrity contribute to breast cancer progression by rendering breast epithelial cells more invasive. My project will shed light on whether these invasive processes also alter DNA repair and contribute to genome stability. Understanding of the interrelationships among integrin signaling, cell-cell junctions, and genome stability will contribute to understanding normal breast cell processes and open up investigations on how these may go awry in cancer progression.
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Zhang, Yuan. "Cell-cell interactions and Gossypol's effects on cell functions of primary cultured Human Breast Epthelial, Stromal and Adipose Stromal cells /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488187763845791.
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Lara, Oscar R. "Immunomagnetic cell separation further applications of the quadrupole magnetic cell sorter /." Columbus, Ohio : Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5fnum=osu1064338539.
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Thesis (Ph. D.)--Ohio State University, 2003.Title from first page of PDF file. Document formatted into pages; contains xxi, 179 p.; also contains graphics (some col.). Includes abstract and vita. Advisor: Jeffrey, Dept. of Chemical Engineering. Includes bibliographical references (p. 160-169).
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Wood, Ian Varnum. "Engineering cell-cell and cell-matrix interactions via cell surface chemistry modification." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415511.
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Adzahar, Noor Suhana Binti. "Effects of Merkel cell polyomavirus T antigen expression on cell transformation of Merkel cells." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15589/.
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Merkel cell carcinoma (MCC) is a rare but highly metastatic skin cancer that affects immunosuppressed individuals. The MCC tumour arises from mechanoreceptor merkel cells in the basal layer of the epidermis and is able to spread through the dermal lymphatic system. Merkel cell polyomavirus (MCPyV) has been detected in the majority of MCC tumour samples. Truncation mutations of the large tumour antigen (LT) are observed in the integrated genome rendering the virus replication defective. These replication-disabling mutations are only present in MCPyV isolates found in cancers and absent from viruses derived from non-tumour tissues. As such aberrant expression of truncated LT (tLT) and small T (ST) antigens is thought to be implicated in MCC development. Elucidating the cellular pathways affected by the MCPyV T antigens involved in oncogenesis and tumour progression is essential to understand the effects of these oncoproteins in cellular transformation and tumourigenesis. A quantitative proteomic approach has been used to identify cellular proteins and pathways that are differentially expressed upon expression of MCPyV tLT. Bioinformatic analysis of the stable isotope labelling by amino acid in cell culture (SILAC) datasets highlight several pathways that are dysregulated upon tLT expression. These pathways include cell cycle regulation, cell death and survival, and cell-cell connections. Further analysis confirmed the effects of MCPyV tLT on these pathways showing alterations within the cell cycle, specifically disrupting the G1 checkpoint to enhance entry to the Sphase, which may prolonged the S phase to allow viral DNA replication. In addition, results suggest that MCPyV tLT expression may also delay the apoptosis-inducing properties of various compounds but was not capable to fully inhibit the apoptotic cascade. In contrast, although proteomic analysis highlighted a number of cell-cell connections related pathways to be differentially altered upon tLT expression, follow up experiments were not able to confirm these results.
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McKenzie, Jenny Alison Gill. "TNF-α signalling to the cell-cell junctions and the cytoskeleton in endothelial cells." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412705.
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Hill, William. "Heterotypic cell-cell interactions between KrasG12D cells and normal neighbours in early pancreatic cancer." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/119038/.
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At the initial stages of tumourigenesis, transformation occurs in a single cell within a healthy epithelial sheet. Competitive interactions between normal and Ras-transformed cells can drive the elimination of mutant cells from tissues to protect from carcinogenesis. Moreover, we have previously demonstrated that normal cells detect and eliminate Ras-transformed cells via differential EphA2 signalling. KrasG12D expressing cells (KrasG12D cells) initiate and drive the earliest stages of pancreatic cancer yet it is unclear if normal pancreatic cells can eliminate oncogenic cells. Here we use low level, stochastic induction of KrasG12D mutations in the pancreas to model the interaction of normal and transformed epithelial cells. We show that Ras-transformed cells adopt a contractile morphology and are eliminated from healthy tissue when present at low numbers. When surrounded by normal cells, KrasG12D cells become segregated, increase in compactness and are often extruded. We find that E-cadherin-based cell-cell contacts are downregulated and internalised in mutant cells when surrounded by normal neighbours in an EphA2-dependent manner. Our evidence also suggests that normal cells suppress progression of Ras-transformed cells to an early disease state. Together, this study suggests that non-transformed pancreatic epithelial cells can eliminate KrasG12D cells from the tissue via EphA2 signalling. These data identify a novel putative tumour-suppressive mechanism in the adult pancreas that mutant cells must first overcome to drive tumourigenesis. Understanding the earliest stages of pancreatic carcinogenesis will provide insight into how risk factors promote disease and may elucidate how pancreatic cancer spreads around the body.
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BARBERI, CHIARA. "Myeloma cells induce the accumulation of activated CD94low NK cells by cell-to-cell contacts involving CD56 molecules." Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/996094.
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Natural Killer (NK) cells represent innate effector cells potentially able to play a role during the immune response against Multiple Myeloma (MM). To better define the distribution and the specific properties of NK cell subsets during MM disease, we analyzed their features in the bone marrow and peripheral blood of newly diagnosed MM patients. Our findings revealed that, in both compartments, NK cells were more abundant than in healthy donors. Among total MM-NK cells, a significant increase of CD94lowCD56dim NK cell subset was observed, which already appears in clinical precursor conditions leading to MM, namely monoclonal gammopathy of undetermined significance and smoldering MM, and eventually accumulates with disease progression. Moreover, a consistent fraction of CD94lowCD56dim NK cells was in a proliferation phase. When analyzed for their killing abilities, they represented the main cytotoxic NK cell subset against autologous MM cells. In vitro, MM cells could rapidly induce the expansion of the CD94lowCD56dim NK cells subset, thus reminiscent of that observed in MM patients. Mechanistically, this accumulation relied on cell to cell contacts between MM and NK cells and required both activation via DNAM-1 and homophilic interaction with CD56 expressed on MM cells. Considering the growing variety of combination treatments aimed at enhancing NK cell-mediated cytotoxicity against MM, these results may also be informative for optimizing current immunotherapeutic approaches.
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Théard, Delphine Francine. "P27Kip1 in cell-cell adhesion and cell polarity." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/291442056.
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Hadjisavas, Michael. "Induction of mitogenesis and cell-cell adhesion by porcine seminal plasma." Title page, contents and abstract only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phh1293.pdf.
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Includes list of publications by the author. Includes bibliographical references (leaves 103-123) Evaluates the nature of the interactions occurring between semen and cells of the uterus that occur following mating in pigs. Describes a novel ability of porcine seminal plasma to induce dose dependent cell-cell adhesion and mitogenesis amongst peripheral blood lymphocytes in vitro.
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Liu, Hao. "Dendritic cell development directed by stromal cells." Thesis, University of York, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516409.
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Crawford, A. "How B cells influence T cell responses." Thesis, University of Edinburgh, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.645118.
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Although studies using B cell deficient mice have been useful in understanding the importance of B cells under different conditions, it is difficult to then dissect exactly how B cells could be regulating T cell responses. By transferring OT-II transgenic T cells into either B cell deficient (μMT) or C57BL/6 mice, expansion and contraction of T cells can be tracked ex vivo. Expansion of OT-II cells is reduced in μMT mice compared to C57BL/6 mice. Thus, B cells can provide costimulatory signals, secrete cytokines and influence the lymphoid microarchitecture. To dissect which B cell factor(s) are involved in enhancing OT-II T cell expansion, a model system was used where one molecule on the B cells is depleted at one time. This was achieved by creating bone-marrow chimeras using a combination of μMT bone-marrow and wildtype or deficient bone-marrow. Thus, all the B cells are either wildtype or deficient for a particular molecule. The molecules examined were MHC-II, which is required for antigen presentation, CD40, due to its costimulatory role, and lymphotoxin-alpha, for its role in maintenance of splenic architecture. Using the OT-II adoptive transfer system, we have shown a requirement for MHC-II but not CD40 on B cells for efficient T cell expansion. In light of these observations, the role of B cell-derived MHC-II for T cell memory generation was examined. To do this, I used MHC-II tetramers to track a polyclonal population of T cells in the host. Using this technique, I have shown that T cell memory is also diminished when the B cells do not express MHC-II. Thus, a cognate interaction with B cells is required for both efficient expansion and memory generation of CD4+ T cells.
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El-Sherbiny, Yasser Mohamed. "Natural killer cells and plasma cell neoplasia." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438481.
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Worapamorn, Wilairat. "Cell-surface proteoglycan expression by periodontal cells /." St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16097.pdf.
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Borysiewicz, L. K. "Cell mediated immunity to human cytomegalovirus infection (cytotoxic T cell and natural killer cell mediated lysis of human cytomegalovirus infected cells)." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/37949.
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Falk, Anna. "Stem cells : proliferation, differentiation, migration /." Stockholm, 2005. http://diss.kib.ki.se/2006/91-7140-497-X/.
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Kavikondala, Sushma. "Dendritic cell and B cell interactions in systemic lupuserythematosus." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39793710.
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Su, Jing. "Knowledge discovery of cell-cell and cell-surface interactions." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22648.
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Thesis (Ph. D.)--Biomedical Engineering, Georgia Institute of Technology, 2008.Committee Chair: Meredith, Carson; Committee Co-Chair: Galis, Zorina; Committee Co-Chair: McIntire, Larry; Committee Member: García, Andrés; Committee Member: Prausnitz, Mark.
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Palovuori, R. (Riitta). "Regulation of cell-cell adhesion and actin cytoskeleton in non-transformed and transformed epithelial cells." Doctoral thesis, University of Oulu, 2003. http://urn.fi/urn:isbn:9514269306.
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Abstract
Epithelial cell-cell adhesions have a critical role in morphogenesis, establishment and maintenance of tissue architecture, cell-cell communication, normal cell growth and differentiation. These adhesions are disrupted during malignant transformation and tumour cell invasion. Several kinases, phosphatases and small GTPases regulate cell-cell contacts. In the present work we investigated the dynamics of cell-cell adhesion structures after microinjection of fluorophore tagged vinculin, during transformation caused by an active Src tyrosine kinase and during Helicobacter pylori infection. The regulatory role of Rac GTPase as well as the behaviour of actin and cadherin were analysed in all these conditions.
Microinjection of vinculin into bovine kidney epithelial MDBK cells induced release of actin, cadherin and plakoglobin to cytoplasm of the cells, caused disruption of protein complexes at adherens and tight junctions that finally led to formation of polykaryons. Activated Rac GTPase, in turn, enhanced accumulation of cadherin to membranes and thereby diminished the formation of polykaryons, whereas inactive Rac removed cadherin from membranes. Incorporation of vinculin to lateral membranes took place also in acidifying and depolarising conditions where cell fusions were prevented. Thus, the membrane potential seemed to control fusion ability. In src-MDCK cells, activation of Src kinase led to disintegration of adherens junctions. Clusters of junctional components and bundles of actin were seen at the basal surface already within 30 min after Src activation. p120ctn was the only component of adherens junction whose relocation correlated to its phosphorylation. Inhibition of Src by a specific inhibitor PP2 restored the cubic morphology of the cells and accumulated cadherin back to lateral walls. Still p120ctn remained in cytoplasm and thereby was not responsible for the epithelial phenotype. Activation of Rac GTPase by Tiam1 also increased the amount of cadherin at lateral membranes and maintained the morphology of src-MDCK cells practically normal after activation of Src kinase. In the same way, actin cytoskeleton was reorganised in gastric carcinoma cells in response to infection with H. pylori via activation of Rac signalling pathway. Hence, Rac and cadherin seem to be the major players in the maintenance of epithelial cell morphology.
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Poon, Tak Kwong. "Pre-malignant transformation of normal mammary epithelial cells compromises tensional homeostasis at cell-cell junctions." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54566.
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Cell-cell junctions regulate the form and function of epithelial tissues, in part, by mechanically coupling adjacent cells together. Unlike normal cells, pre-malignant cells are capable of mechanically uncoupling these junctions in response to motogenic factors such that the cells become invasive and, ultimately malignant. Therefore, I asked whether the mechanical responses of cell-cell junctions to increases in intracellular tension are altered in pre-malignant mammary epithelial cells in the absence of such motogenic factors. In an effort to answer this question I altered the intracellular tension on the cell-cell junctions of normal (EpH4) and pre-malignant oncogenic ras-transformed (EpRas) mammary epithelial cells either chronically, by altering the density of cells attached to a rigid substratum, or acutely, by physically extending (i.e. ‘stretching’) confluent monolayers of cells attached to a compliant silicone rubber substrate. When intracellular tension was chronically increased, the tension-sensitive protein zyxin relocalized to cell-cell junctions in normal, but not pre-malignant cells. The zyxin relocalization in normal cells was associated with a junctional increase in the phosphorylated form of myosin light chain 2 (MLC2) suggesting that it may involve actomyosin contractility. The same differential in zyxin relocalization and phosphorylated MLC2 accumulation occurred when the intracellular tension was acutely increased in the two cell types. This differential was blocked by Rho-ROCK inhibition which indicates that it may be dependent on actomyosin contractility. In addition, apical actin structure reorganization occurred when intracellular tension was acutely increased in the normal cells that did not occur in the pre-malignant cells. Taken together, these observations led me to conclude that the ability of cell-cell junctions to respond in a mechanosensory-appropriate manner to changes in intracellular tension is compromised in ras-transformed pre-malignant mammary epithelial cells. Acute pharmacologic inhibition of oncogenic Ras-mediated increases in MAPK and/or PI3K signalling did not correct this compromised response. Therefore, this compromised mechanosensitivity, which may functionally contribute to the ability of pre-malignant cells to become invasive in response to motogenic factors, may be initiated by long term epigenetic changes that occur under conditions of stable oncogenic transformation.Medicine, Faculty of
Graduate
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Zidane, Mohammed [Verfasser]. "Epigenetic and exosome-mediated cell-cell communication in follicular cells and preimplantation embryos / Mohammed Zidane." Bonn : Universitäts- und Landesbibliothek Bonn, 2017. http://d-nb.info/1155302974/34.
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Miess, H. "Identification of metabolic genes essential for proliferation of clear cell Renal Cell Carcinoma (ccRCC) cells." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1462468/.
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Kidney cancer accounts for 2-3% of adult malignancies with clear cell renal cell carcinoma (ccRCC) being the most common histological subtype (70-80% of cases). Interestingly, ccRCCs show a highly distinct metabolic phenotype making this disease stand out amongst other cancer types. The underlying causes of the aberrant metabolism in ccRCC are not fully understood, but metabolic transformation could provide novel strategies for targeted therapies in this disease. The pVHL tumour suppressor is located on chromosome 3p21, which is frequently lost in ccRCC. pVHL is a negative regulator of the Hypoxia-inducible factor (HIF), which orchestrates the cellular response to oxygen deprivation and might contribute to the aberrant metabolic phenotype of ccRCC cells. In order to reveal metabolic weaknesses in ccRCC, a customised RNAi screen targeting 230 different metabolic enzymes, regulators and nutrient transporters was performed. The screen was performed in a panel of 5 ccRCC pVHL-null cell lines and included their counterparts with reconstituted pVHL, in order to also identify potential vulnerabilities that depend on VHL function. With this approach, several genes that are essential for ccRCC cell viability but dispensable for the survival of non-malignant renal epithelial cells were identified. It was found that ccRCC cell lines are highly sensitive to ablation of components of the glutathione-dependent reactive oxygen species (ROS) detoxification system. Silencing of enzymes of the glutathione biosynthesis pathway or different glutathione peroxidases (GPXs) severely impaired cell viability. One of the precursors of glutathione biosynthesis is glutamate, which is generated from glutamine by glutaminase (GLS). Interestingly, there is evidence that ccRCCs are highly dependent on the MYC oncogene, which induces many enzymes within the glutaminolysis pathway. Indeed, we found that glutamine starvation or chemical inhibition of GLS reduced proliferation and viability of ccRCC cells, confirming the importance of this pathway in ccRCC. In conclusion, the study reported in this thesis provides insight into the metabolic dependencies of ccRCC cells and emphasises the need for a solid anti-oxidant system for ccRCC cell survival and proliferation. Concomitantly, the reliance of ccRCC cells on glutamine and glutathione is a vulnerability that could potentially be exploited for diagnostic and/or therapeutical applications.
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Kaplinsky, Joseph John. "Single cell analysis and cell sorting using microfluidic devices with application to circulating tumour cells." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9474.
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This thesis describes the development of integrated microfluidic technology for single cell proteomic analysis, focusing on circulating tumour cells (CTCs). While single cell proteomic analysis has wide applicability across biology and medicine, CTCs form an ideal first application. Circulating tumour cells are intimately involved in metastasis, the step in cancer overwhelmingly responsible for death, yet have proved hard to study. Single cell microfluidic technology is ideal first because the quantity of material available is inherently at the level of a few cells and second because cell to cell variation is of great interest. Chapter 1 is an introduction to the field. In chapter 2 a microfluidic sandwich assay for quantification of protein at the single cell level is described. In chapter 3 the isolation of CTCs in a microfluidic device is described. This relies on taking the output of the CellSearch® system and inputing it to a microfluidic device. While CTCs were identified, the result showed that a more systematic approach is required for counting and integration with the single cell assay previously described. Chapters 4 and 5 describe development of technology suitable for counting and isolation of CTCs integrated into a microfluidic device with single cell proteomic analysis, although the work done here makes use of fluorescently labelled beads and model cell lines rather than CTCs from patient samples. Chapter 4 describes microfluidic cytometry that can be used to count and identify a labelled population of cells, such as stained CTCs. Chapter 5 describes the prelimary development of a sorting system suitable for isolation of CTCs integrated with the cytometer.
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Li, Jing. "Effects of intrinsic & extrinsic factors on the growth and differentiation of human mesenchymal stem cells." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36434450.
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Mohib, Kanishka. "Embryonic Stem Cell Extracts Possess Immune Modulatory Properties That Prevent Dendritic Cell Maturation and T Cell Activation." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22794.
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Embryonic stem cells (ESC) possess immune privileged properties and have the capacity to modulate immune activation. ESCs can persist across allogeneic immunological barriers, prevent lymphocyte proliferation in mixed lymphocyte reaction (MLR) assays and can promote graft acceptance. However, clinical application of live ESC to treat immunological disorders is not feasible as live ESC can form teratoma in-vivo. In order to harness these properties of ESCs without adverse risk to patients, we hypothesized that ESC derived extracts may retain immune modulatory properties of whole cells and therefore could be used to abrogate allo-immune responses. We found addition of ESC-extracts from human lines H1 and H9, significantly prevented T cell proliferation in allogeneic MLRs. These results were confirmed using murine J1 ESC line. In-vitro studies showed human ESC EXT were able to modulate maturation of human monocyte derived dendritic cells (DC) by suppressing up-regulation of important co-stimulatory and maturation markers CD80, HLA-DR and CD83. In addition, DCs educated in the presence of human ESC extracts significantly lost their ability to stimulate purified allogeneic T cells compared to control extract treated DCs. We also determined that ESC extracts have an independent effect on T cells. ESC extracts prevented T cell proliferation in response to anti CD3/CD28 stimulation. In MLRs, ESC derived factors significantly down-regulated IL-2 and IFN-γ expression, while up-regulating TGF-β and Foxp3 expression. Furthermore, lymphocytes and purified T cells activated with anti-CD3/CD28, ConA and PMA proliferated poorly in the presence of ESC derived factors, while proliferation in response to ionomycin was not affected. Western blot analysis indicated that ESC derived factors prevented PKC-θ phosphorylation without influencing total PKC-θ levels. Moreover, IκB-α degradation was abrogated, confirming absence of PKC-θ activity. Therefore, ESC extracts have potent immune suppressive properties and may have clinical applications in ameliorating transplant rejection and autoimmune conditions.
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Kavikondala, Sushma. "Dendritic cell and B cell interactions in systemic lupus erythematosus." View the Table of Contents & Abstract, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39711523.
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Kozyrska, Katarzyna. "The mechanisms underlying mechanical cell competition and leader cell migration in mammalian epithelia." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289434.
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Cell competition is a form of cell-cell signalling that results in the elimination of less fit cells from a tissue by their fitter counterparts. I take advantage of an established in vitro model of cell competition using Madin-Darby canine kidney (MDCK) cells to shed insight into the molecular basis of cell competition in epithelial cells. In this system, silencing of the tumour suppressor scribble (scribKD) results in a 'loser' phenotype whereby scribKD cells are specifically eliminated from the monolayer by surrounding wild-type cells. More specifically, scribKD cells are compacted into tight clones through activation of a directed, collective migration in the wild-type population: scribKD are 'mechanical losers' and delaminate and die due to an intrinsic hypersensitivity to high cell density. Remarkably, p53 activation is both necessary and sufficient for this mechanical loser cell status. I first investigate the role of E-, N-, and P-cadherin in the directed migration between scribKD and wild-type cells and in scribKD cell loser status. I show that differential expression of E-cadherin between scribKD losers and wild-type winners is required but not sufficient for directed migration and has no impact on loser cell status. I also show that elevation of neither E-cadherin nor N-cadherin is sufficient to induce directed migration or loser status, but that P-cadherin may play a role in both. I next focus on translating findings about the molecular details of competition from the scribKD set-up into a system where p53 differences alone drive the formation and elimination of mechanical losers. I show that the ROCK - P-p38 - p53 pathway activated in response to mechanical compaction in scribKD cells is conserved in p53-driven losers. In the latter part of my thesis, I characterise the directed migration observed during MDCK competition by drawing parallels to canonical leader-follower migration. Canonical leader cells emerge when epithelial sheets are wounded and, by becoming migratory, drive collective cell migration of follower cells, which results in wound closure. It was not known what confers the leader cell fate. I show that p53 and its effector p21 (and potentially other cyclin-dependent kinase inhibitors) are the key drivers of leader cell migration. I demonstrate that p53-induced leaders use the same molecular pathways that have been shown to drive leader cell migration during wound healing and, in fact, p53 and p21 are also elevated in leaders generated by wounding. Importantly, I establish that p53 activity drives efficient wound closure. Lastly, I show that leader cells are often eliminated by cell competition in the final stages of wound closure, as their elevated p53 mediates their hypersensitivity to density. The model incorporating these data proposes that cellular damage during wounding generates cells with elevated p53, which become leaders and drive wound healing, but these are then cleared once the wound is closed because their high p53 levels cause them to become mechanical losers.
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Burrows, Tanya Dee. "Cell-cell and cell-matrix interactions in human placental implantation." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339467.
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Timp, Winston (Winston G. ). "Study of cell-cell communication using 3D living cell microarrays." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42059.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 135-152).
Cellular behavior is not dictated solely from within; it is also guided by a myriad of external cues. If cells are removed from their natural environment, apart from the microenvironment and social context they are accustomed to, it is difficult to study their behavior in any meaningful way. To that end, I describe a method for using optical trapping for positioning cells with submicron accuracy in three dimensions, then encapsulating them in hydrogel, in order to mimic the in vivo microenvironment. This process has been carefully optimized for cell viability, checking both prokaryotic and eukaryotic cells for membrane integrity and metabolic activity. To demonstrate the utility of this system, I have looked at a model "quorum sensing" system in Vibrio Fischeri, which operates by the emission and detection of a small chemical signal, an acyl-homoserine lactone. Through synthetic biology, I have engineered plasmids which express "sending" and "receiving" genes. Bacteria containing these plasmids were formed into complex 3D patterns, designed to assay signaling response. The gene expression of the bacteria was tracked over time using fluorescent proteins as reporters. A model for this system was composed using a finite element method to simulate signal transport through the hydrogel, and simple mass-action kinetic equations to simulate the resulting protein expression over time.
by Winston Timp.
Ph.D.
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Agarwal, Kitty. "Characterization of cell-secreted microvesicles: modulators of cell-cell communication." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1388511983.
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Bair, Elisabeth Laurine. "Cell-cell and cell-matrix interactions involved in cancer invasion." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280673.
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In order for a cancer to metastasize, it must first invade through the basement membrane that surrounds it, invade blood vessels and travel through the bloodstream to a new location where it extravasates the vessel and begins growing at the new site. The mechanisms by which a cancer becomes able to invade and metastasize are currently under intense study. Interactions of the cell with its environment via cell-cell contacts, extracellular matrix (ECM) interactions, and circulating proteins are thought to play a major role in signaling for these invasive processes to occur. Upregulation of proteolytic enzymes, such as the matrix metalloproteases, is suspected of being involved in the metastatic process. Cell-cell and cell-matrix contacts via integrins and cadherins are necessary for upregulation of the matrix metalloprotease matrilysin in oral squamous cell carcinoma. In an effort to identify the factors involved in upregulation of matrilysin expression detected in a co-culture of oral squamous cell carcinoma (SCC) cells and fibroblast cells, a coculture model designed to represent the actual tumor environment, we show that inhibition of beta1 integrin, E-cadherin, and N-cadherin with blocking antibodies thoroughly decreases the induction of matrilysin in the co-culture model. This demonstrates that interactions between cancer cells and normal cells surrounding them may allow for invasion and metastasis. The protein 90K may also play a role in the invasive process of prostate cancer. It functions as an immune modulator upregulating cytokines that induce MMPs and we show that it can induce matrilysin expression in prostate cancer cells. It also functions in cell aggregation, which can help cells survive during metastasis. For this reason, expression of 90K in prostate cancer, which we examined, may be indicative of aggressive disease, making 90K a potentially useful tumor marker. Cell-matrix contacts are also important for the transmembrane matrix metalloprotease MT1-MMP cleavage of laminin-10. We demonstrate that recombinant MT1-MMP is able to cleave human laminin-10 into four distinct products. This allows for prostate cancer cell migration on laminin-10 coated substrates, which can be inhibited with the addition of MT1-MMP antisense oligonucleotides. Ln-10 cleavage also occurs in vivo in human prostate tissue, indicating that this cell-matrix interaction has in vivo relevance in human prostate cancer.
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Radmaneshfar, Elahe. "Mathematical modelling of the cell cycle stress response." Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=192232.
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Wiklund, Sofia. "Effects on immune cell viability, morphology and proliferation in a sub-microliter cell sampler system." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-89982.
Full textAbstract:
Today, most traditional method used in the research of immune cells, such as flow cytometry and microscopy, are based on average values of cell responses. However, immune cells are heterogeneous and respond differently to a given stimuli. There is also a risk that important, but rare, behaviors of individual cells are missed when a larger population of immune cells is analyzed. Also, flow cytometry and microscopy do not allow long-term survival of cells; these methods lack the ability to do dynamic long-term analysis of motile immune cells, i.e. studies of cell-cell interactions, morphology and proliferation. In a patient who is affected by cancer, the cell heterogeneity contributes to the ability to battle various types of cancer or virus infections. In an outbreak, immune cells recognize and kill tumor cells. However, the number of specific immune cells is sometimes too few to kill all the tumor cells in a successful way. One way to help these patients is to isolate, select out and cultivate the active immune cells with capacity to kill tumor cells. The Cell Physic Laboratory (a part of the department of Applied Physics) at the Royal Institute of Technology (KTH) has developed a method for single-cell analysis where the immune cells are trapped in microwells in a silicon chip. The immune cells are then studied by using fluorescence microscopy in an inverted setup. The method enables high-throughput experiments due to the parallelization. Furthermore, since the immune cells survive long periods in the chip, the cells can be analyzed over several days up to weeks. The research group has also developed a semi-automatic ‘cell-picker’. The cell-picker will be used in combination with the developed method for single-cell analysis, which enables picking of cells of interest. In this report, experiments for the characterization and evaluation of the biocompatibility of two generations of the cell-picker will be presented. The experiments include development of a protocol for the cell-picking process, studies of the survival time of transferred cells for both generation of the cell-picker and studies of surface coating in the chip in order to increase the biocompatibility. The preliminary results indicate that the cell-picker has potential to be used as a selection tool for immune cells of interest.
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Goddard, Ruth Victoria. "Generation of in vitro B-cell chronic lymphocytic leukaemia-specific T cell responses using dendritic cells." Thesis, University of Plymouth, 2002. http://hdl.handle.net/10026.1/2695.
Full textAbstract:
Immunotherapy using dendritic cells has shown encouraging results in both haematological and non-haematological malignancies. In this study, monocyte-derived dendritic cells from patients with B-cell Chronic Lymphocytic Leukaemia were generated by culture in Interleukin-4 and Granulocyte Macrophage-Colony Stimulating Factor. Lysate-pulsed autologous dendritic cells were used as antigen presenting cells in co-culture with autologous B-cell Chronic Lymphocytic Leukaemia T-cells. B-cell Chronic Lymphocytic Leukaemia T-cells stimulated with B-cell Chronic Lymphocytic Leukaemia lysate-pulsed autologous dendritic cells showed a significant increase in cell surface expression of Interleukin-2 Receptor (CD25), Interferongamma secretion and cytotoxicity against autologous B-cell Chronic Lymphocytic Leukaemia B-cell targets hut not against targets from healthy volunteers. Responses were only stimulated by the B-cell Chronic Lymphocytic Leukaemia B cell lysate. Cytotoxicity was Major Histocompatibility Complex Class II restricted. The addition of maturation agents such as Lipopolysaccharide, Tumour Necrosis Factor-alpha and Polyriboinosinic Polyribocytidylic Acid to monocyte derived dendritic cells was unsuccessful at increasing anti-tumour responses. Pre-treatment of T cells with Interleukin-15 before stimulation by lysate pulsed autologous dendritic cells increased numbers of activated cells, cytokine secretion and specific cytotoxicity to B-cell Chronic Lymphocytic Leukaemia 8-cells. Fusion of monocyte derived dendritic cells and B-cell Chronic Lymphocytic Leukaemia B-cells generated both Major Histocompatibility Complex Class I and Class II restricted cytotoxicity to B-cell Chronic Lymphocytic Leukaemia B-cell targets. When B-cell lysates were analysed using reducing sodium dodecyl sulphate-polyacrylamide gel electrophoresis, a B-cell Chronic Lymphocytic Leukaemia specific hand at 42,000 Dalton and other patient specific bands were observed. Only the 65,000 Dalton and 42,000 Dalton hands were capable of stimulating comparable T cell responses as the whole lysate. The 65,000 Dalton band from normal healthy volunteers showed a dominant peptide that closely matched Human Serum Albumin. The 42,000 Dalton band from B-cell Chronic Lymphocytic Leukaemia patients showed a possible match with Human Actin.