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Title: The role of Hippo signalling in cell fate decisions in mouse embryonic stem cells and pre-implantation development
Author: Brimson, Christopher A.
ISNI:       0000 0004 5923 5840
Awarding Body: University of Bath
Current Institution: University of Bath
Date of Award: 2016
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The Hippo signalling pathway is a conserved kinase cascade involved in the regulation of tissue growth and organ size. Activation of the Hippo pathway through multiple upstream inputs results in phosphorylation and inactivation of the transcriptional co-activator, Yes associated protein (Yap). While the role of Yap as an oncogene and an effector of the Hippo pathway is well established, its role in cellular differentiation is less well known. In this present work I have utilised quantitative immunofluorescence analysis to examine the expression of Yap in the differentiation of mouse embryonic stem cells (mESCs). I show that differentiation of mESCs is accompanied by an initial increase in nuclear Yap expression. Furthermore, I show that this increase in nuclear Yap expression is associated with differentiation towards the primitive endoderm lineage (PrE). Moreover, small molecule inhibition of Yap was able to decrease the proportion of cells differentiating towards PrE. Following on from these in vitro studies, I examine the expression of Yap in vivo in the corresponding differentiation event in mouse preimplantation embryos. I show that increased nuclear Yap expression is associated with expression of the PrE-specific transcription factor Gata6 during specification and eventual sorting of the PrE. Culturing embryos in the presence of small molecule inhibitors of Yap resulted in decreased expression of Gata6 and a reduction in trophectoderm cell number. These studies demonstrate that Yap is involved in the process of cellular differentiation and is associated with specification of the PrE lineage. Finally I attempt to create an inducible knockout of Yap in mESCs using a serial targeting strategy, with the intention of creating a model system in which to examine the role of Yap in mESCs.
Supervisor: Munoz-Descalzo, Silvia ; Tosh, David Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available