title: Oocyte expression, secretion and somatic cell interaction of mouse bone morphogenetic protein 15 during the peri-ovulatory period.
abstract: Bone morphogenetic protein 15 (BMP15) is a key intraovarian growth factor regulating mammalian fertility, yet expression and localisation of different BMP15 protein forms within ovarian follicles around the time of the preovulatory LH surge remains unclear. Using immunoblotting and immunocytochemistry, the present study identified that post-translationally processed BMP15 proregion and mature proteins are increasingly expressed and localised with cumulus and granulosa cells from mice treated with pregnant mare's serum gonadotropin (PMSG) + human chorionic gonadotrophin (hCG). However, this increased expression was absent in cumulus-oocyte complexes matured in vitro. Pull-down assays further revealed that the recombinant BMP15 proregion is capable of specific interaction with isolated granulosa cells. To verify an oocyte, and not somatic cell, origin of Bmp15 mRNA and coregulated growth differentiation factor 9 (Gdf9), in situ hybridisation and quantitative polymerase chain reaction results confirmed the exclusive oocyte localisation of Bmp15 and Gdf9, regardless of treatment or assay method. Relative oocyte expression levels of Bmp15 and Gdf9 decreased significantly after PMSG + hCG treatment; nevertheless, throughout all treatments, the Bmp15:Gdf9 mRNA expression ratio remained unchanged. Together, these data provide evidence that the preovulatory LH surge leads to upregulation of several forms of BMP15 protein secreted by the oocyte for putative sequestration and/or interaction with ovarian follicular somatic cells.
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
authors.forename: Brigitta
authors.initials: B
authors.lastname: Mester
authors.affiliation: School of Paediatrics and Reproductive Health, Robinson Institute, Research Centre for Reproductive Health, University of Adelaide, Adelaide, SA 5005, Australia.
authors.forename: Lesley J
authors.initials: LJ
authors.lastname: Ritter
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
authors.forename: Janet L
authors.initials: JL
authors.lastname: Pitman
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
authors.forename: Adrian H
authors.initials: AH
authors.lastname: Bibby
authors.affiliation: School of Paediatrics and Reproductive Health, Robinson Institute, Research Centre for Reproductive Health, University of Adelaide, Adelaide, SA 5005, Australia.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Gilchrist
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
authors.forename: Kenneth P
authors.initials: KP
authors.lastname: McNatty
authors.affiliation: AgResearch, Reproductive Biology, Invermay Agricultural Centre, Private Bag 50034, Mosgiel 9053, New Zealand.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Juengel
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
authors.forename: C Joy
authors.initials: CJ
authors.lastname: McIntosh
mesh_terms: D000818:Animals; D055430:Bone Morphogenetic Protein 15 / Q000378:metabolism*; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D054885:Cumulus Cells / Q000187:drug effects / Q000378:metabolism; D004338:Drug Combinations; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism; D055429:Growth Differentiation Factor 9 / Q000378:metabolism; D051379:Mice; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism*; D010060:Ovulation / Q000187:drug effects / Q000378:metabolism*
chemical_list: D055430:Bone Morphogenetic Protein 15; D006063:Chorionic Gonadotropin; D004338:Drug Combinations; C525898:Gdf9 protein, mouse; D006064:Gonadotropins, Equine; D055429:Growth Differentiation Factor 9; C006116:chorionic gonadotropin, pregnant mare serum gonadotropin drug combination