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Title: Signalling pathways in lymphocyte development and survival
Author: Henley, T. W.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
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Vav proteins regulate receptor-mediated calcium mobilisation, a process for which the N-terminal calponin homology (CH) domain appears critical, yet the mechanisms by which this operate are unknown. We therefore attempted to characterise the role of this domain in vivo and identify mechanisms by which the CH domain regulates calcium mobilisation by generating mice expressing Vav1 with an N74A point mutation within the CH domain. Mice carrying the germline N74A mutation were generated and the presence of the mutation within the intact locus confirmed. Analysis of the expression of the mutant protein showed little to no protein was expressed in cells from the spleen or thymi. The defective expression of the mutant protein therefore precluded study of its role in lymphocyte development and function. We also aimed to study the effect of mutations within the Vav1 CH domain by retroviral complementation analysis. We successfully set up an optimised system for stem cell transduction and lymphocyte reconstitution in alymphoid recipient mice, but found limitations with this methodology when analysing relatively subtle changes in the proportions of lymphocyte subpopulations due to variations in reconstitution efficiency between mice. Like Vav proteins, members of the P13K family are also crucial for B cell survival and recent evidence suggests that survival mediated by the cytokine BAFF operates partly via Akt-dependent mechanisms. We therefore sought to determine the extent to which loss of the P13K subunit P110δ in B cells impacted on BAFF-mediated responses. We found that P110δ-deficient Be cells were impaired in BAFF-mediated survival and cell growth in vitro. These cells also showed an impaired ability to compete with wildtype B cells in competitive repopulation experiments. B cells that lack Vav proteins were also impaired in their ability to respond to BAFF-mediated survival and growth signals and showed reduced levels of the BAFF-receptor, although the significance of this remains to be tested.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available