This Article Full Text Full Text (PDF) Supplemental Data Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sasseville, M. Articles by Richard, F. J. Search for Related Content PubMed PubMed Citation Articles by Sasseville, M. Articles by Richard, F. J. Pubmed/NCBI databases Substance via MeSH

Regulation of Gap Junctions in Porcine Cumulus-Oocyte Complexes: Contributions of Granulosa Cell Contact, Gonadotropins, and Lipid Rafts

Centre de Recherche en Biologie de la Reproduction (M.S., M.-C.G., C.G., F.J.R.), Département des Sciences Animales, Université Laval, Québec, Canada G1V 0A6; Centre de Recherche en Biologie de la Reproduction (R.S.), Département d’Obstétrique-Gynécologie, Faculté de Médecine, Université Laval, Québec, Canada G1V 4G2; and Robinson Institute, School of Paediatrics and Reproductive Health (M.S., R.B.G.), Medical School, University of Adelaide, Adelaide 5005, Australia

Address all correspondence and requests for reprints to: François J. Richard, Centre de Recherche en Biologie de la Reproduction, Département des Sciences Animales, Université Laval, Québec, Canada. E-mail: francois.richard{at}fsaa.ulaval.ca.

Gap-junctional communication (GJC) plays a central role in oocyte growth. However, little is known about the regulation of connexin 43 (Cx43)-based gap-junction channels in cumulus-oocyte complexes (COCs) during in vitro maturation. We show that rupture of COCs from mural granulosa cells up-regulates Cx43-mediated GJC and that gonadotropins signal GJC breakdown by recruiting Cx43 to lipid rafts when oocyte meiosis resumes. Oocyte calcein uptake through gap junctions increases during early in vitro oocyte maturation and remains high until 18 h, when it falls simultaneously with the oocyte germinal vesicle breakdown. Immunodetection of Cx43 and fluorescence recovery after photobleaching assays revealed that the increase of GJC is independent of gonadotropins but requires RNA transcription, RNA polyadenylation, and translation. GJC rupture, in contrast, is achieved by a gonadotropin-dependent mechanism involving recruitment of Cx43 to clustered lipid rafts. These results show that GJC up-regulation in COCs in in vitro culture is independent of gonadotropins and transcriptionally regulated. However, GJC breakdown is gonadotropin dependent and mediated by the clustering of Cx43 in lipid raft microdomains. In conclusion, this study supports a functional role of lipid raft clustering of Cx43 in GJC breakdown in the COCs during in vitro maturation.