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Title: Signalling pathways regulating inflammatory cytokine expression
Author: Testar, Jodie
ISNI:       0000 0001 3516 3799
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2008
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My research has strived to understand two different aspects of immune cell response to stimuli: i) cross talk between innate and adaptive immune responses; ii) regulation of inflammatory signalling by a novel phosphoprotein, Arhgef101. Canonical and non-canonical NFκB signalling pathways have been described to date, each inducing a distinct gene expression profile. Current understanding indicates the canonical being mainly involved in innate- and non-canonical being mostly involved in adaptive immunity. Using a T cell hybridoma model, I established that chronic activation of the canonical pathway by TNFα led to up-regulation of components of the non-canonical pathway, specifically Re1B and p100. Hypothesising that cells exposed chronically to TNFa would then have enhanced non-canonical activation propagating the inflammatory response, CD27 was identified as a model system for activating the non-canonical NFκB pathway. In spite of exhaustive attempts with this system and other receptor systems, none were found to be capable of inducing robust and reproducible non-canonical NFκB activation. We have identified a novel phosphorylation designated Arhgef101. Arhgef101 was found to undergo tyrosine phosphorylation in the murine macrophage cell line, RAW 264.1, after LPS stimulation. Murine tissue screening for Arhgef101 RNA showed ubiquitous expression. No compartmental, membrane or actin filament associations were observed. Overexpression of Arhgef101 in RAW cells resulted in overproduction of TNFa but not IL-6 after TLR4 stimulation, when compared to untransfected cells. Overexpression in the murine fibroblast cell line, NIH 3T3, amplified both IL6 and KC production in response to IL1 and LPS. Primary-transcript quantitative PCR suggests a potential transcriptional regulatory role for Arhgef101. With no detectable differences in the major signalling pathway NFκB, ERK, JNK, or p38 MAPK these data implicate Arhgef101 as a potential signalling adaptor involved in an, as yet, unidentified signalling pathway.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available