title: Oocyte induction of EGF responsiveness in somatic cells is associated with the acquisition of porcine oocyte developmental competence.
abstract: Oocytes progressively acquire the competence to support embryo development as oogenesis proceeds with ovarian folliculogenesis. The objectives of this study were to investigate oocyte-secreted factor (OSF) participation in the development of somatic cell epidermal growth factor (EGF) responsiveness associated with oocyte developmental competence. A well-established porcine model was employed using oocytes from small (<4 mm) vs medium sized (>4 mm) antral follicles, representing low vs moderate developmental competence, respectively. Cumulus-oocyte complexes (COCs) were treated in vitro with inducers of oocyte maturation, and cumulus cell functions and oocyte developmental competence were assessed. COCs from small follicles responded to FSH but, unlike COCs from larger follicles, were incapable of responding to EGF family growth factors known to mediate oocyte maturation in vivo, exhibiting perturbed cumulus expansion and expression of associated transcripts (HAS2 and TNFAIP6). Low and moderate competence COCs expressed equivalent levels of EGF receptor (EGFR) mRNA; however, the former had less total EGFR protein leading to failed activation of phospho-EGFR and phospho-ERK1/2, despite equivalent total ERK1/2 protein levels. Native OSFs from moderate, but not from low, competence oocytes established EGF responsiveness in low competence COCs. Four candidate recombinant OSFs failed to mimic the actions of native OSFs in regulating cumulus expansion. Treatment with OSFs and EGF enhanced oocyte competence but only of the low competence COCs. These data suggest that developmental acquisition by the oocyte of capacity to regulate EGF responsiveness in the oocyte's somatic cells is a major milestone in the oocyte's developmental program and contributes to coordinated oocyte and somatic cell development.
authors: School of Paediatrics and Reproductive Health and Robinson Research Institute (L.J.R., S.S., R.B.G.) Australian Research Council Centre of Excellence in Nanoscale BioPhotonics (L.J.R.), The University of Adelaide, Adelaide, SA 5005, Australia; Institute of Agriculture (S.S.), Department of Biological Production, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan; and Discipline of Obstetrics and Gynaecology (R.B.G.), School of Women's and Children's Health, University of New South Wales, Sydney, NSW 2052, Australia.
authors: Lesley J
authors: LJ
authors: Ritter
authors: Satoshi
authors: S
authors: Sugimura
authors: Robert B
authors: RB
authors: Gilchrist
mesh_terms: D000818:Animals; D015153:Blotting, Western; D054885:Cumulus Cells / Q000166:cytology* / Q000187:drug effects*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine
chemical_list: D004815:Epidermal Growth Factor; D005640:Follicle Stimulating Hormone; D066246:ErbB Receptors