Dissertations / Theses on the topic 'Keratinocyte'
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1
Kalaji, Ruba. "Mechanisms regulating keratinocyte morphology." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501083.
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White, Stephen John. "Ex vivo keratinocyte gene therapy." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268103.
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Allan, G. "Gene expression during keratinocyte differentiation." Thesis, University of Newcastle Upon Tyne, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233424.
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Schilling, David. "Stress and Growth Related Keratinocyte Pathways." Diss., lmu, 2003. http://nbn-resolving.de/urn:nbn:de:bvb:19-10451.
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Elliott, Richard John. "Keratinocyte responses to novel proopiomelanocortin agents." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419623.
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St, George-Smith Stephen. "Psoriasis : the role of the keratinocyte." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339965.
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Roshan, Amit. "Stochasticity and order : studies of keratinocyte proliferation." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/252966.
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A central tenet of stem cell biology has been that proliferating tissues are maintained through a cellular hierarchy comprising of self-renewing stem cells at the apex, multiple lineage-restricted short-lived progenitor cells, and post-mitotic differentiated cells. The wide range of colony sizes in cultured human keratinocytes has been taken to support this hypothesis. Contrary to this model, researchers using genetic lineage tracing in mouse epidermis have inferred a single progenitor population for homeostasis, and a quiescent stem cell population activated upon wounding or genetic mutation. To study the proliferative behaviour of human keratinocytes, I used live imaging in vitro at single cell resolution. This shows two modes of proliferation: Type 1 cell division is stochastic with equal odds of generating dividing or non-dividing progeny, while Type 2 cell division predominantly produces two dividing daughters. These two modes are sufficient to explain the entire range of colony sizes seen after 7-12 days of culture and does not require a spectrum of proliferative ability. This insight provides a simple way to study the effects of external factors on cell fate. To exemplify this, I observed the effects of epidermal growth factor (EGF) and the Wnt agonist R-spondin on proliferation. Here I find proliferation in type 2 colonies changes by changing the proportion of cells dividing. This has implications for the limited success of EGF therapies in clinical trials following burns. To examine clonal contributions to wound repair, I used the mouse oesophageal epithelium which is exclusively composed of, and maintained by, a single progenitor population. I developed a micro-endoscopic wounding technique that produced localised superficial wounds. Here, I found that these wounds healed by uniform contribution from surrounding keratinocytes, demonstrating that reserve stem cells are not obligatory for wound repair. In summary, my work shows that human keratinocytes in vitro have two, and only two, modes of proliferation: a stochastic mode that is insensitive to external EGF signalling, and a EGF-sensitive exponential mode. Additionally, proliferation during wound repair can occur with stochastically dividing progenitors, and does not obligate stem cell recruitment in vivo.
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Norgett, Elizabeth Emma. "Intercellular junctions in keratinocyte differentiation and disease." Thesis, Queen Mary, University of London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417795.
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Liebig, Timo Christian. "Rho GTPases in Keratinocyte adhesion and differentiation." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499127.
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McMullan, Rachel Jane. "Regulation of keratinocyte function by Rho kinase." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275126.
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Poomsawat, Sopee. "Regulation of keratinocyte integrins by scatter factor." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343964.
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Wong, Chee Wai. "Dermal fibroblast extracellular matrix regulates keratinocyte behaviour." Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/68292.
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This project explored using dermal fibroblast-derived extracellular matrices (ECMs) to recapitulate the keratinocyte microenvironmental niche in vitro. The data indicated that fibroblast-derived matrices better supported keratinocytes expansion than substrates of type I collagen. ECM composition was found to profoundly alter the gene expression profiles of keratinocytes grown on these matrices, in that foetal matrices triggered expression of cell cycle genes, whereas adult matrices triggered the expression of a balance of differentiation and cell cycle genes.
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Kiwanuka, Elizabeth. "CCN2 – Keratinocyte Interactions In Vitro and In Vivo." Doctoral thesis, Uppsala universitet, Plastikkirurgi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-213566.
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Cutaneous wound healing is a complex process involving the migration of inflammatory cells to the wound site, deposition of extracellular matrix, and the reestablishment of an intact epithelial barrier. Re-epithelialization depends on the proliferation and directional migration of keratinocytes from the wound edges. Initially, keratinocytes migrate over a provisional wound matrix that is rich in fibronectin, and as the wound heals the provisional matrix becomes replaced by one consisting of collagen and proteoglycans. Re-epithelialization is tightly regulated by a variety of peptides such as growth factors, cytokines and proteases, and abnormalities may result in chronic non-healing wounds or hypertrophic scars. CCN2 (Connective Tissue Growth Factor) is a multifunctional protein with effects on cells and their interactions with the connective tissue. CCN2 is expressed in a variety of cell types and regulates numerous cell functions including proliferation, differentiation, adhesion, migration and stimulation of collagen production. While the importance of CCN2 for the fibrotic response has been well studied, its involvement in keratinocyte function has not yet been fully explored. Using an in vivo wound model, the expression of CCN2 was captured at the leading keratinocyte edge during re-epithelialization. In vitro, exogenous addition of CCN2 to human keratinocyte cultures promoted keratinocyte migration. Subsequently, integrin a5b1 was identified as an important mediator of CCN2 enhancement of keratinocyte adhesion to fibronectin. CCN2 activated the FAK-MAPK signaling pathway, and pretreatment with MEK1 specific inhibitor PD98059 markedly reduced CCN2-promoted keratinocyte migration. In vitro, CCN2 expression was induced by TGF-β1. Compared with inhibiting the SMAD pathway, blocking MAPK was more effective in reducing TGF-β1-induced CCN2 mRNA and protein expression. In addition, CCN2-induced keratinocyte spreading required FAK. Treatment with CCN2 led to actin disassembly and altered the activity of the Rho proteins and p190RhoGAP in keratinocytes. Furthermore, Cdc42 mediated CCN2-induced cell polarity. In conclusion, using in vivo and in vitro models, CCN2 was shown to regulate keratinocyte function by promoting keratinocyte adhesion, spreading and migration. A complete understanding of CCN2 expression in keratinocytes is crucial in order to develop novel therapies for wound healing.
14
Barker, Carol. "Differentiation and metabolism in the human epidermal keratinocyte." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301068.
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Khan, Erum. "Characterisation of 2D and 3D oral keratinocyte cultures." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3463/.
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Oral keratinocyte behaviour were analysed in two and three dimensional cultures of an immortalised human H400 cellline and primary rat keratinocytes (PRKs) using a novel method of quantitative microscopy, RT-PCR data and immunohistochemistry profiles. Monolayer cultures were established in high and low calcium media at different cell densities and analysed prior to generating 3D organotypic cultures (OCs) onde-epidermalised dermis (DED), polyethylene terephthalate porous membrane (PET) and collagen gels for up to 14 days.H400 and PRKs proliferation in monolayer cultures was greater in low calcium medium compared with high calcium medium.Gene expression analysis indicated that adhesion and structural molecules including E-cadherin, plakophilin, desmocollin-3, desmogleins-3 and cytokeratins-1, -5, -6, -10, -13 were up-regulated by days 6 and 8 compared with day 4in high calcium medium. Immunohistochemical profiles and gene expression data of OCs on DED recapitulated those of normal oral epithelium. The final thickness of OCs as well as the degree of maturation/stratification was significantly greater on DED compared with other scaffolds used. Quantitative microscopy approaches enabled unbiased architectural characterisation of OCs and the ability to relate stratified organotypic epithelial structures to the normal oral mucosa. H400 and PRK OCs on DED at the air liquid interface demonstrated similar characteristics in terms of gene expression and protein distribution to the normal tissue architecture.
16
Hopley, J. P. "Toxicity studies in a differentiating epidermal keratinocyte culture." Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/847531/.
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A keratinocyte culture derived from rat sublingual epithelium has been developed and characterised both morphologically and enzymically. Morphologically the culture closely resembles that found in vivo. The culture has been studied comprehensively using light and electron microscopy (scanning and transmission). The culture procedure has been optimised such that minimal amounts of time and materials are required. The culture, although heteroploid, shows a high degree of homogeneity with minimal fibroblastic contamination. Total adhered protein, total DNA content, 3H-thymidine incorporation, ornithine decarboxylase activity, acid phosphatase activity, prolinase and malate dehydrogenase activity have been studied at various phases in the cultures growth cycle. An initial study using 3,3',4,4' tetrachlorobiphenyl indicated that acid phosphatase, prolinase and total protein may be the best parameters for studying toxic insult in these cells, together with morphological examination by electron microscopy and light microscopy using acridine orange as a stain. Subsequently, comparisons of the 3,3',4,4' and 2,2,4,4' tetrachlorobiphenyl isomers, benzo(a)pyrene and 20-methylcholanthrene were made. Acid phosphatase and prolinase appeared to be useful markers of the toxic effects of these compounds showing alterations consistent with some in vivo findings. These changes were observed at concentrations of the compounds that did not produce significant cytotoxicity. Morphological examination showed changes with some similarities to some carcinomas in vivo. The effects of these compounds on keratin production within the cells has also been undertaken. A comparison has also been made of the relative toxicities of several compounds in the keratinocyte culture and in the human embryonic lung fibroblast line (BCL-Dl); the keratinocyte system appeared to be more sensitive to irritant compounds. Studies of the metabolic capabilities of the culture using benzo(a)pyrene as substrate have also been undertaken. Although the capacity of these cells to metabolise foreign compounds was low, they show hydroxylation, glucuronidation and sulphation activity. In longer term tests (14-21 day), the system shows enhanced sensitivity, the point of commitment of the culture (ie., differentiation and stratification) being a critical time. The methods used showed good reproducibility and were easily performed. The system may, therefore, provide a useful sensitive screening test for detection of compounds affecting differentiation (e. g irritants and carcinogens).
17
Zhu, Ling. "Regulation of Human Epidermal Keratinocyte Survival and Differentiation." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1196178754.
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Cloud, Caitlin. "Oxygen tension regulates keratinocyte migration in aged skin." Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/1131.
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The migration of keratinocytes across wound beds is a key step in dermal wound healing. In aged human skin, wound healing rates decrease, and reactive oxygen species damage accumulation increases, but it is unclear if these factors relate specifically to migration of human skin keratinocytes (HSKs). In this study, two concentrations of oxygen (4% and 21%) were used to model low and high oxidative stress to produce varying levels of reactive oxygen species. When migration of HSKs from young and old primary skin were compared by scratch assay, those from old skin migrated faster in high oxygen tension than did young HSKs, which was an opposite trend from that seen in young skin. An intense increase in reactive oxygen species at margins immediately after scratching was seen in both young and old HSKs, but reactive oxygen species disappeared from young skin at 21% oxygen most quickly. These cells also had the slowest migration. These findings suggest that old and young keratinocytes respond differently to oxidative stress, and that migration of keratinocytes--a key step in re-epithelialization of wounds, is effected by the efficacy of reactive oxygen species removal.
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Rubin, Philip. "Cultured allogeneic keratinocyte transplantation in the Large White pig." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248187.
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Appleby, Mark William. "Oncogene expression and the modulation of keratinocyte self renewal." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306476.
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Barbaroux, Jean-Baptiste Olivier Stephen. "The trance system in langerhans cell and keratinocyte homeostasis." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499092.
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Owens, Dewi W. "A study of keratinocyte differentiation and adhesion in vitro." Thesis, University of Glasgow, 1997. http://theses.gla.ac.uk/1099/.
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In this study, I used the serum-free MCDB 153 culture system to investigate calcium-induced keratinocyte differentiation. Treating normal human keratinocytes with high extracellular calcium concentrations (1mM) increased the proportion of cells expressing differentiation-specific proteins. I showed that this was not caused by calcium-induced cell-cycle arrest, nor was it a consequence of stratification. However, the expression of differentiation-specific proteins was preceded by the formation of cadherin-mediated cell-cell adhesions. The likely importance of the cadherin-mediated adhesions in initiation the differentiation program was confirmed in two ways. Firstly, clustering cell-surface E-cadherin in low extracellular calcium using monoclonal antibodies increased the proportion of keratinocytes expressing differentiation-specific proteins. Secondly, suppressing the formation of cadherin-mediated cell-cell adhesions using synthetic peptide analogous to the cadherin recognition domain attenuated the calcium-induced expression of differentiation-specific proteins. These data are consistent with a role for the cadherin-mediated cell-cell adhesions in initiating the keratinocyte differentiation program in response to calcium in vitro. A second aspect of this project involved an investigation of the role played by the Src-family of protein tyrosine kinases at calcium-induced cadherin-mediated adherens junctions. The ubiquitously expressed members of this family, c-Src, Fyn and c-Yes were localised to the cadherin-mediated adhesions formed in response to high extracellular calcium. Treating adherent keratinocytes maintained in low extracellular calcium with a specific Src kinase inhibitor, PD162531, induced the assembly of cadherin-mediated cell-cell adhesions leading to the formation of contiguous groups of cells similar to those seen in response to high extracellular calcium. The data presented are consistent with a role for the Src kinases in regulating adherens junction turnover but do not exclude a role also in modulating aspects of differentiation.
23
Webber, David George. "Studies of keratinocyte MHC expression in cutaneous hypersensitivity responses." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294576.
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Al-Raawi, Diaa Ali Naji. "Role of JARID2 in the regulation of keratinocyte differentiation." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8427/.
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JARID2 is a member of the Jumonji family of histone demethylases. It plays an important role in the regulation of gene expression and is indispensable for normal vertebrate development. JARID2 interacts with the chromatin modifying polycomb repressive complex-2 (PRC2) for modulating its activity and its binding to chromatin. It is central to the gene regulatory network of embryonic stem (ES) cells but its role in lineage-committed cells, such as Keratinocytes, is not well studied. In this study, we studied the role of JARID2 in several lineage-committed cells including keratinocytes. Using an in-vitro keratinocyte differentiation model, we show that a novel form of JARID2 is up-regulated during differentiation. To investigate the functional mechanism of this form, genome-wide gene expression profiling using RNA-sequencing was performed. JARID2 knockout cells showed down-regulation of many epidermal differentiation genes and up-regulation of cell cycle genes. Interestingly, the effect of JARID2 knockout on epidermal differentiation genes could be rescued by exogenously expressing the novel form. This indicates that this form of JARID2 promotes activation of differentiation genes in contrast to PRC2 which is needed for repression of differentiation.
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OLIVERO, CARLOTTA. "Defining the causal association between human beta papillomavirus infection, keratinocyte stem cells expansion and skin cancer development." Doctoral thesis, Università del Piemonte Orientale, 2017. http://hdl.handle.net/11579/87003.
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I papillomavirus umani (HPV) sono piccoli virus nudi contenenti un genoma a doppia elica di DNA circolare di 8 kb che infettano gli epiteli squamosi stratificati cutanei e mucosali di differenti distretti corporei. Gli HPV possono stabilire infezioni latenti in individui sani, ma inducono anche lesioni neoplastiche benigne o maligne in base alle proprietà oncogene specifiche dei differenti genotipi. Fino ad oggi sono stati identificati più di 180 genotipi differenti di HPV che sono stati classificati in 5 generi sulla base dell’analisi filogenetica. Il genere Alpha (α-HPV) è il più caratterizzato e comprende i genotipi a tropismo mucosale associati all’ insorgenza di carcinoma a livello genitale (ad esempio HPV16 e 18). Gli HPV appartenenti al genere β (β-HPV) sono evoluzionisticamente distinti dal genere α e causano infezioni inapparenti o asintomatiche molto diffuse nella popolazione generale. Nei pazienti affetti da epidermodisplasia verruciforme (EV), una immunodeficienza primaria caratterizzata da un’alta suscettibilità all’infezione da β-HPV, questi virus replicano con alta efficienza, sviluppano il loro pieno potenziale trasformante, inducendo numerose lesioni simil verrucose con alto rischio di progressione a carcinoma cutaneo. Sebbene il loro coinvolgimento nel processo di carcinogenesi cutanea in pazienti immunocompetenti e immunosoppressi non-EV (con immunosoppressione primaria o acquisita) è ancora materia di dibattito, numerose evidenze epidemiologiche e sperimentali suggeriscono un ruolo carcinogenico di questi virus che inizia nelle fasi precoci e contribuisce alla patogenesi del carcinoma cutaneo. Il nostro gruppo ha dimostrato precedentemente la presenza di prodotti dei geni virali e l’amplificazione del genoma virale in lesioni cutanee precancerose derivate da pazienti trapiantati d’organo (OTR, Organ Transplant Recipient). Questi risultati rafforzano l’evidenza di un coinvolgimento dei β-HPVs nella patogenesi del carcinoma cutaneo.
Sulla base dei dati già acquisiti, abbiamo studiato i meccanismi molecolari alla base dell’induzione del carcinoma cutaneo indotto da β-HPV in pazienti immunocompromessi attraverso differenti approcci, quali il modello di topo transgenico HPV8 e il saggio di tumorigenicita’ in vivo di tumori derivati da OTR.
Pe capire il ruolo di β-HPV nello sviluppo del carcinoma cutaneo, è importante conoscere dove questo virus naturalmente si localizza. L’ipotesi attuale è che il reservoir di β-HPV risieda in cellule staminali con ciclo cellulare rallentato presenti nel follicolo pilifero (HF-KSC); tuttavia, la precisa popolazione di HF-KSC coinvolta nell’infezione latente di β-HPV è ancora sconosciuta. Per determinare il ruolo delle HF-KSC nel carcinoma cutaneo indotto da β-HPV, abbiamo utilizzato un modello di topo transgenico nel quale il promotore della cheratina 14 guida l’espressione della regione precoce di HPV8 (HPV8tg). I topi HPV8tg presentano uno spessore della cute piu’ ampio rispetto ai topi wild type e mostrano una cute iperproliferante. La proliferazione dei cheratinociti del follicolo pilifero è evidente nella popolazione di cellule staminali Lrig1+ (69 vs 55%, p<001, n=6), ma non lo è nelle popolazioni CD34+, LGR5+ e LGR6+. Questo è in linea con l’osservazione dell’espanzione dei cheratinociti Lrig1+ di 2,8 volte e dell’efficienza di formare colonie di 3.8 volte. In accordo con questi risultati, abbiamo osservato l’espressione nucleare di p63 in questa popolazione, nell’infindibulum e nella cute interfollicolare fiancheggiante, associata a un cambiamento di espressione tra la forma TA di p63 in ΔNp63 nella cute dei topi HPV8tg. Le cheratosi dei pazienti EV e alcune cheratosi attiniche (AK) di pazienti non EV mostrano un istologia simile associata alla riattivazione di β-HPV e all’espressione nucleare di p63 nell’ infindibulum e nella cute perifollicolare. Questi dati suggeriscono che il campo di cancerizzazione indotto da β-HPV inizia dalla “junctional zone” e predispone al carcinoma cutaneo..
Inoltre abbiamo realizzato un modello umanizzato di xenotrapianto ortotopico utilizzando tumori cutanei derivati da OTR. Questa tecnica permette di aumentare la disponibilità dei tumori cutanei – che è una delle limitazioni nell’ambito della ricerca sui tumori cutanei-, analizzare in dettaglio i meccanismi molecolari coinvolti nella tumorigenesi e identificare l’infezione e l’espressione di β-HPV in queste lesioni. Inoltre, questa tecnica permette di studiare la progressione della malattia da una situazione pre-cancerosa a una cancerosa, ad esempio da AK a SCC come riportato in questa tesi, che non può essere studiato a livello umano per la naturale necessità di rimuovere la lesione prima dell’evoluzione maligna.
In questo contesto, rimane da stabilire se l’immunosoppressione faciliti la carcinogenesi anche attraverso la riduzione dell’immunosorveglianza. Per verificare questa ipotesi e generare un modello murino che ricapitolasse gli eventi che si verificano nei pazienti trapiantati, abbiamo incrociato i topi transgenici HPV8 (background genetico FVB/N) con i topi deficienti per il gene RAG2 (background genetico C57BL/6), che non producono cellule B e T. I risultati ottenuti fino ad ora con la generazione F2 indicano che l’immunosoppressione facilita la carcinogenesi anche inibendo l’immunosorveglianza del tumore, come dimostrato dai dati ottenuti; infatti,il numero di tumori cutanei nella cute dei topi HPV8+:Rag2-/- e il loro grado di displasia è risultato significativamente maggiore rispetto ai topi HPV8+:Rag2+/+.
Nell'insieme, i risultati ottenuti in questo studio contribuiscono a chiarire la storia naturale dell’infezione da β-HPV e rafforzano l’ipotesi di un ruolo di questi virus nello sviluppo del tumore cutaneo.
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JOANNY-CRISCI, FRANCOISE. "Action des ultraviolets a sur des keratinocytes humains en culture." Nancy 1, 1993. http://www.theses.fr/1993NAN10204.
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Daehn, Ilse Sofia, and chickychulita@yahoo com. "Effect of growth factors on T-lymphocyte induced keratinocyte apoptosis." Flinders University. Department of Medicine-Biotechnology, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20071215.233705.
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Atopic eczema is a T-lymphocyte mediated chronic inflammatory skin disorder. The
interaction of CD4+ T-lymphocytes with epidermal keratinocytes results in
dysregulated, chronic inflammation and altered barrier function. T-lymphocyte induced
keratinocyte apoptosis has been proposed as a mechanism by which epidermal integrity
is impaired in eczema. Apoptosis of keratinocytes is thought to result from Tlymphocyte
associated Fas ligand (FasL) binding to the death receptor Fas on
keratinocytes. The primary aim of this project was to characterize the induction of
keratinocyte apoptosis by T-lymphocytes and address the hypothesis that insulin-like
growth factor-I (IGF-1), transforming growth factor [beta]1 (TGF[beta]1) and a milk derived
growth factor extract containing TGF[beta] and IGF-I (whey growth factor extract; WGFE)
protect keratinocytes from T-lymphocyte mediated apoptosis.
To address the aims of this project, an in vitro co-culture model was developed combining T-lymphocytes with keratinocytes. Co-cultures were initially established using human Jurkat T-lymphocytes and human HaCaT keratinocytes with more extensive characterisation undertaken using primary CD4+ T-lymphocytes together with HaCaTs or normal human epidermal keratinocytes (NHEK). Annexin V and propidium iodide staining was established as the primary method for measuring keratinocyte apoptosis with this validated using sodium butyrate a known inducer of apoptosis. Changes in nuclear fragmentation and cell morphology were also examined as a key feature of apoptosis. The involvement of the Fas pathway was investigated by assessing T-lymphocyte FasL expression, keratinocyte Fas expression and downstream caspase activation. Inflammatory cytokines IFN[gamma] and TNF[alpha] were also examined due to their ability to induce Fas expression.
Studies performed with T-lymphocytes demonstrated that keratinocyte apoptosis was induced, with this due primarily to direct T-lymphocytes and keratinocytes interactions, rather than soluble mediators in the co-culture milieu. Activated T-lymphocytes were found to have high levels of FasL and to upregulate keratinocyte Fas expression. The increased keratinocyte Fas was associated with increased IFN[gamma] levels in the co-culture media and activation of the caspase cascade. A Fas blocking antibody prevented T-lymphocyte induced keratinocyte apoptosis demonstrating that this was a Fas dependent event.
As the primary function of keratinocytes is to terminally differentiate, the differentiation status of the cells induced to undergo apoptosis was examined. It was demonstrated that T-lymphocytes decrease the intensity of ?6 integrin expression by the keratinocytes. This marker identifies undifferentiated basal cells as high expressors of [alpha]6, with cells in the early stages of differentiation pathway found to be low expressors of [alpha]6. Co-staining with Annexin V demonstrated that the apoptotic keratinocytes were low expressors of [alpha]6 and thus cells committed to the early stages of differentiation. This suggested that the T-lymphocytes initiated the onset of keratinocyte terminal differentiation with this linked to the cells being more susceptible to death induced by T-lymphocyte by activation of the Fas pathway.
The ability of TGF[beta]1, IGF-I and WGFE to inhibit T-lymphocyte induced keratinocyte apoptosis was examined. A combination of recombinant TGF[beta] (10ng) & IGF-I (100ng) was able to significantly inhibit keratinocyte apoptosis. A similar result was obtained with WGFE, and although these growth factor treatments were able to reduce the elevated IFN[gamma] levels in the co-culture media, they did not reduce T-lymphocyte induced Fas upregulation. The TGF?1 and IGF-I combination as well as WGFE did however prevent the T-lymphocyte induced shift from [alpha]6 bright to dim expressing keratinocytes. As such, the growth factor combinations appeared to protect the keratinocytes from T-lymphocyte mediated apoptosis by preventing them from committing to terminal differentiation.
The studies in this thesis have characterised the Fas associated mechanisms by which T-lymphocytes induce keratinocyte apoptosis and suggest specific growth factor combinations may have the potential to ameliorate the reduced barrier function associated with inflammatory skin conditions such as atopic eczema.
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Chávez, Muñoz Claudia I. "Keratinocyte-releasable factors modulate extracellular matrix components in dermal fibroblasts." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/37005.
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A fine balance between the synthesis and degradation of extracellular
matrix (ECM) is required in maintaining the structural integrity of healing tissue.
An imbalance in ECM expression leads to fibrotic conditions such as
hypertrophic scars (HS). It has been demonstrated that keratinocyte-releasable
factors can function as ECM modulating factors (MMP-1 and type I collagen) in
fibroblasts. We have shown that Stratifin (SFN) is an MMP-1 stimulatory factor in
fibroblasts that failed to suppress the expression of type I collagen in fibroblasts.
SFN is an intracellular protein that lacks a signal peptide. As such, it is critical to
explore its mechanism of release and identify the keratinocyte-derived collageninhibiting
factor(s) for dermal fibroblasts. In this doctoral research project I
hypothesize that keratinocyte-releasable factor(s) function as a stop signal(s) for
wound healing by modulating the expression of key ECM components such as
MMP-1 and type I collagen in fibroblasts.
Two specific objectives were accomplished to address these issues.
Under objective 1, the mechanism by which SFN is released has been explored.
The findings demonstrate that SFN is released via exosomes in a Ca²⁺
dependant fashion. Moreover, only differentiated keratinocytes release SFN.
Exosome-associated SFN exhibits a potent MMP-1 stimulatory effect. Under
objective 2, using a series of systematic protein purification methods followed by
mass spectroscopy, two proteins (SPARC and SFN) that inhibited collagen
production by dermal fibroblasts were identified in keratinocyte-conditioned
media. Using co-immunoprecipitation and 3D modeling, we determined that SFN and SPARC form a complex thereby regulating type I collagen expression in
fibroblasts. The levels of these proteins in fibrotic tissues (animal and human)
were also evaluated and a differential expression of these proteins between
normal and fibrotic tissue confirmed their potential role in development of fibrotic
condition.
In conclusion, the identification of the mechanism of release of SFN and
the identification of SPARC/SFN complex contribute to the understanding of how
these factors are involved in the wound healing process. Also, SPARC/SFN
complex provides us with another anti-fibrogenic factor that may be used to
generate an effective therapeutic agent to treat HS frequently developed
following burn injury, deep trauma and/or surgical incisions.
29
Thomas, Gareth J. "The role of αv integrins in regulating keratinocyte behaviour." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341916.
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Hodivala, Kairbaan Jimmy. "Changes in integrin expression during keratinocyte terminal differentiation and immortalization." Thesis, University College London (University of London), 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307679.
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Wessagowit, Vasarat. "Keratinocyte gene expression profile in recessive dystrophic epidermolysis bullosa wounds." Thesis, King's College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408868.
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Clement, Amanda Lynn. "Engineering the Keratinocyte Microenvironment: Harnessing Topography to Direct Cellular Function." Digital WPI, 2015. https://digitalcommons.wpi.edu/etd-dissertations/23.
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Skin wound healing presents a challenging and expensive clinical problem with nearly 20 million wounds requiring intervention leading to an annual cost of more than $8 million. Tissue engineered skin substitutes are valuable not only as a clinical therapy for chronic wounds and severe traumas, but also as in vitro 3D model systems to investigate wound healing and skin pathogenesis. However, these substitutes are limited by a lack of topography at the dermal-epidermal junction (DEJ). In contrast, the native DEJ is characterized by a series of dermal papillae which project upward into the epidermal layer and create physical topographic microniches that support keratinocyte stem cell clustering. In this thesis, we created novel 3D skin model systems to investigate the role of microtopography in regulating keratinocyte function and cell fate using scaffolds containing precisely engineered topographic features. We hypothesized that the microtopography of the DEJ creates distinct keratinocyte microniches that promote epidermal morphogenesis and modulate keratinocyte stem cell clustering which can be harnessed to create a more robust skin substitute that expedites wound closure. Using photolithographic techniques, we created micropatterned DEJ analogs and micropatterned dermal-epidermal regeneration matrices (µDERM) which couple a dermal support matrix to a micropatterned DEJ analog. We found that the incorporation of microtopography into our in vitro skin model resulted in a thicker, more robust epidermal layer. Additionally, we identified three distinct functional keratinocyte niches: the proliferative niche in narrow channels, the synthetic niche in wide channels and the keratinocyte stem cell niche in narrow channels and corner topographies. Ultimately, incorporation of both narrow and wide channels on a single construct allowed us to recreate native keratinocyte stem cell patterning in vitro. These model systems will allow us to investigate the role of cellular microniches in regulating cellular function and epidermal disease pathogenesis as well as to identify topographic cues that enhance the rate of wound healing.
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Sturniolo, Michael Thomas. "Tazarotene-Induced Gene 3: A Novel Regulator of Keratinocyte Differentiation." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1100296278.
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Sayers, Charlotte. "Herpes simplex virus type 1 infection of human keratinocyte cells." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11112.
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Infection of herpes simplex virus type 1 (HSV-1) begins at the epidermis, a stratified layer composed primarily of keratinocytes. The physiologically relevant cell type for the study of HSV-1 assembly is therefore the human keratinocyte. Nonetheless, relatively little is known about the replication of HSV-1 in this natural host cell. Comparison of virus growth in monolayers of keratinocyte cells and Vero cells, a routinely used cell line for HSV-1 studies, revealed that these keratinocytes support a more productive virus replication than Vero cells. Furthermore, newly assembled virus is produced more rapidly in keratinocytes and this enhancement occurs prior to, or upon the initiation of immediate early gene transcription. This augmented replication in keratinocytes can be at least partially attributed to the method of entry of the virus. We have found by penetration assays and electron microscopy that the virus is able to penetrate keratinocyte cells much more rapidly than Vero cells. We have also shown that the virus entry mechanism is more efficient at lower temperatures in nTERT cells, with virus entering cells at temperatures as low as 7°C. Additionally preliminary work implies that depletion of one of the herpes virus entry receptors, Nectin-1, does not affect entry into nTERT cells, whereas entry is reduced up to 65% in HeLa cells. Taken together, these results imply a role for other entry receptors, possibly as yet unidentified, in the entry of human keratinocyte cells. This work also identifies a role for cellular Rab proteins, GTPases essential for the regulation of vesicle trafficking, in HSV-1 infection of keratinocytes. In particular Rab6, which was also found to play a role in infected HeLa cells (Elliott Group), appears to have a similar function in both these cells and together support a model for HSV-1 morphogenesis involving Rab-regulated vesicle trafficking of viral glycoproteins to the cell surface. Several other Rabs identified by this screen now provide interesting opportunities to elucidate further roles of Rab proteins in HSV-1 infection of keratinocyte cells. This project has broadly characterised the replication of HSV-1 in keratinocyte cells and explored the role of Rab GTPases in virus trafficking within keratinocytes - a cell type that is physiologically relevant to infection.
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Michopoulou, Anna. "Receptor syndecan-1 controls MMP-9 expression during keratinocyte migration." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1130.
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La phase de l'épithélialisation de la réparation cutanée se déroule en impliquant plusieurs processus dynamiques et interactifs pendant lesquels les kératinocytes migrent, prolifèrent et se différentient afin de reconstruire la fonction de la barrière. La migration des kératinocytes est l'événement qui détermine l'efficacité du processus entier. Le comportement migratoire est contrôlé au même temps au niveau extracellulaire et intracellulaire et dépend d'interactions dynamiques entre les cellules et leur environnement extracellulaire, des facteurs de croissance et des cytokines. Parmi les protéines de la matrice extracellulaire, la laminine 332 est un substrat d'adhésion majeur des kératinocytes qui joue un rôle important au cours de la migration des kératinocytes, travers son domaine LG4/5 localisé à l'extrémité carboxy-terminale de sa chaine a. Des études récentes ont rapporté que l'induction de la migration des kératinocytes par LG4/5 est dépendante des Métalloprotéinases Matricielles pro-migratoires (MMP)-9 et -1 qui jouent des rôles essentiels au cours de la cicatrisation et surtout pendant la ré-épithélialisation. Etant donné que des travaux antérieurs du laboratoire ont montré que le domaine LG4/5 participe à la dynamique du cytosquelette et à la motilité cellulaire au travers de liaisons avec les récepteurs de type de protéoglycanes à heparane sulfate, syndécan-1 et -4 on a regardé l'implication potentielle de ces récepteurs au processus. Afin d'analyser la participation possible des syndecans dans ce processus, nous avons développé une approche de mutagénèse dirigée dans la protéine LG4/5 recombinante pour altérer les sites de liaison aux syndécan-1 ou -4. Notre analyse PCR et nos résultats de zymographie ont révélé une différence du profile d'activation des MMPs en fonction de la mutation produite et donc de la capacité de la protéine à recruter le syndécan-1 ou le syndécan-4, ainsi que le syndécan-1, et pas la syndécan-4, est impliqué dans l'activation de la production de la MMP-9 par LG4/5. Nous avons ensuite confirmé ces résultats en réduisant l'expression du syndécan-1 dans des kératinocytes et on a pu aussi montrer que le traitement avec des cytokines telles que TNFalpha et IL-1beta, connues pour leur capacité d'induire l'activation de la MMP-9, a produit le même résultat dans ce systéme. L'addition de l'héparine dans nos experiences a inhibé l'activation de l'expression de MMP-9 suggerant que les heparanes sulfates dans syndecan-1 sont impliqué au mécanisme. Pour confirmer ces résultats des experiences avec des séries de syndecan-1 mutés sont en cours. Pour conclure, nos résultats montrent pour la première fois un rôle important de syndecan-1 à l'expression de MMP-9 suggérant que sa re-distribution au front des kératinocytes migratoires puisse éventuellement être liée au clivage ou à la dégradation des protéines de la matrice extracellulaire. En plus, nos résultats proposent que le domain LG4/5 de la laminin 332 libéré soit capable d'affecter la balance de l'expression de la MMP-9 lors de la migration des kératinocytes en leur permettant de traverser le caillot de fibrineDuring skin repair, the epithelialization phase occurs by an orderly series of events whereby keratinocytes migrate, proliferate, and differentiate to restore the barrier function. Keratinocyte migration determines the efficiency of the overall wound repair process. The migratory behaviour is governed at both the extracellular and intracellular levels and depends on the carefully balanced dynamic interactions of the cells with ECM components, growth factors and cytokines. Among extracellular matrix proteins, laminin 332, known as a major adhesion substrate for keratinocytes was shown to contribute to skin reepithelialization through its a3 chain C-terminal domains LG45. Recent studies have reported that LG45 induces keratinocyte migration, an event that relies on the involvement of the pro-migratory matrix metalloproteinases-1 and -9, two MMPs known to play a role in the reepithelialization phase of wound healing. As findings from our laboratory have reported that LG45 domains participate in cytoskeleton dynamic and cell movement through binding of the heparan sulphate proteoglycans syndecan-1 and -4, we analyzed the potential involvement of these receptors in this process. To that end, we have developed a site-directed mutagenesis approach within a recombinant LG45 protein to alter either the syndecan-1 or syndecan-4 binding site. Our PCR analysis and zymography results revealed that depending on the mutants, syndecan-1 or syndecan-4 recruitment induced different MMP activation profile and suggested that syndecan-1 plays a role in LG45 induced MMP-9 expression and activation. We confirmed these results by down regulating syndecans expression in keratinocytes and revealed that this phenomenon also occurred when cells were treated with TNFalpha or IL1beta, two cytokines known to up-regulate MMP-9 expression. Addition of heparin in these experiments abolished MMP-9 expression activation suggesting that syndecan-1 heparan sulfate moieties are involved in this mechanism. Confirming experiments using a series of mutated syndecan-1 in their ectodomain (lacking glycosaminoglycan chains) or in their cytoplasmic tail are ongoing in the lab. Taken together, our data demonstrate for the first time that syndecan-1 plays a pivotal role in MMP-9 expression, suggesting that its re-distribution at the front edge of migrating keratinocyte may have a role to play in the cleavage or degradation of extracellular matrix proteins. Our results further suggest that the released laminin 332 LG45 domain has the ability to impact the MMP9 expression balance during keratinocyte migration therefore facilitating their path through the fibrin clot
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Sturniolo, Michael Thomas. "Tazarotene-induced gene 3 a novel regulator of keratinocyte transglutaminase /." Connect to text online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1100296278.
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Thesis (Ph. D.)--Case Western Reserve University, 2005.[School of Medicine] The Molecular Virology Training Program. Includes bibliographical references. Available online via OhioLINK's ETD Center.
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Joseloff, Elizabeth 1969. "AP-1 regulation during malignant progression of mouse keratinocyte cells." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282562.
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The mouse skin model that has been used to study skin carcinogenesis can be divided into three stages: initiation, promotion, and progression. One genetic change observed during tumor promotion and malignant progression is increased transactivation of the transcription factor AP-1. AP-1 consists of Jun (c-Jun, Jun B, Jun D) and Fos (c-Fos, Fos B, Fra-1, Fra-2) proteins that form Jun:Jun homodimers or Jun:Fos heterodimers. AP-1 binds to a consensus cis-promoter element, the TRE, and transcriptionally regulate a number of genes with various biological functions. By studying the benign mouse keratinocyte cells, 308, and its malignant variant, 10Gy5, it has been shown that 10Gy5 cells have elevated AP-1 activity compared to 308 cells. Reduced AP-1 transactivation in 10Gy5 cells has been correlated with suppression of its malignant phenotype. This research examined the differential AP-1 transactivation in benign 308 and malignant 10Gy5 cells. By examing mechanisms of AP-1 regulation in the two cell lines, differences were observed with post-translational modifications of AP-1. There were differences in phosphorylation of one of the AP-1 family members, Jun B. In addition, AP-1 proteins in 10Gy5 cells appear to be in a fully reduced state, unlike AP-1 proteins in 308 cells. A third difference that was observed was in Jun B steady state protein levels, with decreased Jun B protein in malignant 10Gy5 compared to benign 308 cells. Reduced Jun B protein in 10Gy5 cells was the result of decreased Jun B protein synthesis. Jun B protein may inhibit AP-1 transactivation and cell proliferation. Experiments were performed to determine whether Jun B protein could modulate AP-1 transactivation, cell growth, and tumor formation in 308 and 10Gy5 cells. Altering Jun B protein levels in these keratinocytes affected AP-1 transactivation. Overexpression of Jun B protein in malignant 10Gy5 cells corresponded to an inhibition of cell growth and tumor development. However, overexpression of Jun B protein in 10Gy5 cells was not sufficient to reverse the malignancy, indicating that additional genetic changes are involved in malignant conversion of these keratinocytes. The results of this research suggest that Jun B protein levels may be important during malignant progression of mouse skin.
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Wiszniewski, Ludovic. "Rôle des connexines dans le développement d' épiderme humain reconstruit in vitro." Paris 7, 2002. http://www.theses.fr/2002PA077250.
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Chang, Hsiang-Lin. "Keratinocyte growth factor as a survival factor in human breast cancer." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133214902.
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Geara, Fady. "Mesure de la radiosensibilité "in vitro" des lymphocytes fibroblastes et kératinocytes chez les patients traités par radiothérapie : étude de l'hétérogeneité individuelle et comparaison avec les réactions tissulaires." Paris 11, 1993. http://www.theses.fr/1993PA11T002.
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Wallace, Lee. "Mechanical regulation and characterisation of murine keratinocyte stem cells in vitro." Thesis, University of Newcastle upon Tyne, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.730913.
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Zhu, Alan Jian. "Role of integrins and cadherins in regulating keratinocyte growth and differentiation." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300439.
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Ulrich, Kristina. "Keratinocyte growth factor ; : a novel therapeutic approach to acute lung injury." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405435.
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Jones, Keith Thomas. "The role of intracellular calcium in the control of keratinocyte differentiation." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359170.
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Gajjar, Leena. "The RTE keratinocyte line as an in vitro model for skin." Thesis, University of Surrey, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290400.
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Abbas, Asma A. "HSV-1 INFECTION IN KERATINOCYTE CELL LINES TREATED WITH MITOTIC INHIBITORS." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1303839668.
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Okumura, Tomoyuki. "Neurotrophin receptor p75NTR characterizes human esophageal keratinocyte stem cells in vitro." Kyoto University, 2004. http://hdl.handle.net/2433/147538.
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Zarkoob, Hoda. "Mechanobiology of keratinocyte aggregate formation and its role in wound healing." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5885.
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Wound healing is an intrinsic response to injury or disease that generally results in scarring. In skin, restoration of the barrier function after wounding is critically dependent on re-epithelialization. During re-epithelialization keratinocytes from the wound margin migrate over the wound bed, proliferate and re-differentiate to make an intact epidermis. Mechanical cues may play an important role in epidermal sheet formation and re-epithelization.
Here, polyacrylamide (PA) gels with tunable stiffness were used to study the potential contribution of mechanical properties of the wound bed in re-epithelialization. Live cell imaging and deformation tracking microscopy was performed on primary human keratinocytes maintained on soft (1.2 kPa) and stiff (24 kPa) PA gel substrates. The results of this study indicated that the formation of keratinocyte aggregates was significantly different on soft versus stiff polyacrylamide gels, with smaller spread contact area, increased migration velocities, increased rates of aggregate formation, and more cells per aggregate for keratinocytes cultured on soft gels versus stiff gels, respectively. The differences may be due to cell–cell mechanical signaling generated via local substrate deformations in the underlying substrate. These deformations were substantially larger for soft gels.
Broad-spectrum proteomics was performed to investigate which proteins were expressed differentially on soft and stiff PA gels. Protein lysates from soft and stiff samples were analyzed by LC-MS/MS (Q-Exactive). Expression of 56 proteins differed significantly between keratinocytes on soft and stiff substrate samples. The presence of serotransferrin, one of the most prominent protein candidate presented higher in the soft samples, was confirmed using western blot. Further analysis needs to be conducted to investigate the rest of protein candidate in proteomics results.
The PA gel system was then used to explore the role that keratin intermediate filaments play in mechanosensing and force generation. Knock-out mouse keratinocytes that were missing certain keratins and their corresponding wild type controls demonstrated differences. Knock-outs were less spread out, had impaired actin formation, could not deform the substrate, and hardly made aggregates on soft substrates. These results revealed the importance of keratin intermediate filaments in keratinocyte mechanobiology.
In order to characterize keratinocyte mechanosensing, a needle was used to make controlled local mechanical deformations in soft PA gels in a defined distance from isolated single cells. Keratinocytes responded to needle-induced substrate displacements by changing direction, and migrating towards the needle. The inhibitors, Y27632 and blebbistatin were used to inhibit Rho kinase and myosin phosphorylation. Both Y27632 and blebbistatin impaired directed migration toward the needle.
Together my results reveal new insights on keratinocytes mechanobiology, which could help in the development of novel healing strategies.
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Fernandez, Tara L. "In vitro models for investigating keratinocyte responses to ultraviolet B radiation." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/61515/1/Tara_Fernandez_Thesis.pdf.
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This thesis describes the use of 2- and 3-dimensional cell-based models for studying how skin cells respond to ultraviolet radiation. These methods were used to investigate skin damage and repair after exposure to radiation in the context of skin cancer development. Interactions between different skin cell types were demonstrated as being significant in protecting against ultraviolet radiation-induced skin damage. This has important implications in understanding how skin cancers occur, as well as in the development of new strategies to prevent and treat them.
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Alsrhani, Abdullah Falleh. "Studies in Trypsin as an Alarm Substance in Zebrafish." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1248500/.
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Previous studies have shown that fish release alarming substances into the water to alert their kin to escape from danger. In our laboratory, we found that zebrafish produce trypsin and release it from their gills into the environment when they are under stress. By placing the zebrafish larvae in the middle of a small tank and then placing trypsin at one end of the tank, we observed that the larvae moved away from the trypsin zone and almost to the opposite end of the tank. This escape response was significant and did not occur in response to the control substances, bovine serum albumin (BSA), Russell's viper venom (RVV), and collagen. Also, previously, we had shown that the trypsin could act via a protease-activated receptor-2 (PAR2) on the surface of the cells. Therefore, we hypothesized that trypsin would induce a change in neuronal activity in the brain via PAR2-mediated signaling in cells on the surface of the fish body. To investigate whether the trypsin-responsive cells were surface cells, we generated a primary cell culture of zebrafish keratinocytes, confirmed these cells' identity by specific marker expression, and then incubated these cells with the calcium indicator Fluo-4 and exposed them to trypsin. By using calcium flux assay in a flow-cytometer, we found that trypsin-treated keratinocytes showed an increase in intracellular calcium release. To test whether PAR2 mediates the escape response to trypsin, we treated larvae with a PAR2 antagonist and showed that the trypsin-initiated escape response was abrogated. Furthermore, par2a mutants with knockdown of par2a by the piggyback knockdown method failed to respond to trypsin. Trypsin treatment of adult fish led to an approximately 2-fold increase in brain c-fos mRNA levels 45 mins after trypsin treatment, suggesting that trypsin signals may have reached the brain, probably via a spinothalamic pathway. Taken together, our results reveal a novel trypsin-initiated escape response in fish. These studies should enhance our understanding of fish communication in general and alarm behavior in particular. Furthermore, since pain receptors in other animals are also PAR2, our finding may be useful in exploring pathways of pain reception.