Growth factor regulation of preantral follicle development in the mouse ovary
File(s)
Author(s)
Atess, Victoria
Type
Thesis
Abstract
At, or around, birth female mammals are already endowed with a finite stock of oocytes. The majority are housed within non-growing primordial follicles but, from birth until depletion, a steady trickle initiate growth. The regulation of this process is poorly understood, despite its importance in defining reproductive lifespan. Primordial activation is characterised by oocyte growth, granulosa cell (GC) cuboidalisation and proliferation. N-cadherin is the major cell adhesion molecule (CAM) associated with GC cuboidalisation in mouse. CAMs are known to associate and signal with receptor tyrosine kinases (RTKs). Several RTKs have been implicated in regulating primordial activation and have been localised to GCs. Therefore, we hypothesised that RTKs may regulate primordial activation via interaction with N-cadherin in mouse. Association of candidate RTKs with N-cadherin was assessed by immunofluorescence. ErbB2, an RTK member of the Epidermal growth factor (EGF) family, which relies on heterodimerisation to signal co-localised with N-cadherin in cuboidalising GCs. Furthermore, expression of a downstream anti-proliferative protein, transducer of ErbB2 (TOB1), provides evidence that ErbB2 may regulate the onset of GC proliferation during primordial activation. A suitable antibody was not available to identify a dimer partner, but PCR demonstrated that Egfr and ErbB3 expression. The sensitivity of isolated preantral follicles to EGF, which stimulated follicle growth, and inhibitors to EGFR, which blocked EGF-stimulated follicle growth, demonstrate that EGFR is expressed and available to dimerise with ErbB2 and also provides strong evidence that EGFR signalling is important in preantral GC proliferation. Crucially, culture of whole d4 ovaries in either EGF of Lapatinib, an inhibitor of EGFR/ErbB2 provide evidence to suggest that these proteins regulate mouse primordial activation.
Version
Open Access
Date Issued
2014-10
Date Awarded
2015-02
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Hardy, Kate
Franks, Stephen
Sponsor
Biotechnology and Biological Sciences Research Council (Great Britain)
Publisher Department
Department of Surgery & Cancer
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)