title: Oocyte-secreted growth differentiation factor 9 inhibits BCL-2-interacting mediator of cell death-extra long expression in porcine cumulus cell.
abstract: Oocyte-secreted factors (OSFs) maintain the low incidence of cumulus cell apoptosis. In this report, we described that the presence of oocytes suppressed the expression of proapoptotic protein BCL-2-interacting mediator of cell death-extra long (BIMEL) in porcine cumulus cells. Atretic (terminal deoxynucleotidyl transferase dUTP nick end labeling-positive) cumulus cells strongly expressed BIMEL protein. The healthy cumulus- oocyte complex exhibited a low BIMEL expression in cumulus cell while the removal of oocyte led to an about 2.5-fold (P < 0.5) increased expression in oocytectomized complex (OOX). Coculturing OOXs with denuded oocytes decreased BIMEL expression to the normal level. The similar expression pattern could also be achieved in OOXs treated with exogenous recombinant mouse growth differentiation factor 9 (GDF9), a well-characterized OSF. This inhibitory action of GDF9 was prevented by the addition of a phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Luciferase assay further demonstrated that BIM gene expression was forkhead box O3a (FOXO3a)-dependent because mutation of FOXO3a-binding site on the BIM promoter inhibited luciferase activities. Moreover, the activity of BIM promoter encompassing the FOXO3a-binding site could be regulated by GDF9. Additionally, we found that GDF9 elevated the levels of phosphorylated AKT and FOXO3a, and this process was independent of the SMAD signal pathway. Taken together, we concluded that OSFs, particularly GDF9, maintained the low level of BIMEL expression in cumulus cell through activation of the PI3K/FOXO3a pathway.
authors.affiliation: Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing, China.
authors.forename: Xian-Long
authors.initials: XL
authors.lastname: Wang
authors.forename: Kun
authors.initials: K
authors.lastname: Wang
authors.forename: Shuan
authors.initials: S
authors.lastname: Zhao
authors.forename: Yi
authors.initials: Y
authors.lastname: Wu
authors.forename: Hui
authors.initials: H
authors.lastname: Gao
authors.forename: Shen-Ming
authors.initials: SM
authors.lastname: Zeng
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000235:genetics* / Q000378:metabolism; D000072224:Bcl-2-Like Protein 11; D002478:Cells, Cultured; D054885:Cumulus Cells / Q000187:drug effects* / Q000502:physiology; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D005260:Female; D051858:Forkhead Transcription Factors / Q000378:metabolism; D055429:Growth Differentiation Factor 9 / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D051058:Oncogene Protein v-akt / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D013552:Swine
chemical_list: D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D051858:Forkhead Transcription Factors; D055429:Growth Differentiation Factor 9; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019869:Phosphatidylinositol 3-Kinases; D051058:Oncogene Protein v-akt
keywords: BIM; GDF9; apoptosis; atresia; cumulus cell; cumulus cells; oocyte-follicle interactions; porcine/pig