title: Follicle-stimulating hormone regulates pro-apoptotic protein Bcl-2-interacting mediator of cell death-extra long (BimEL)-induced porcine granulosa cell apoptosis.
abstract: The pro-apoptotic protein Bim (B-cell lymphoma-2 (Bcl-2)-interacting modulator of cell death) has recently been identified and shown to promote cell death in response to several stimuli. In this report, we investigated the role of Bim in porcine follicular atresia. Initially, Bim cDNA was cloned and characterized from porcine ovarian tissue. Porcine Bim had three alternative splicing variants (Bim-extra long, Bim-long, and Bim-short), all containing the consensus Bcl-2 homology 3 domain. We then found the Bim-extra long (Bim(EL)) protein, the most abundant isoform of Bim, was strongly expressed and co-localized with apoptotic (TUNEL-positive) granulosa cells from porcine atretic follicles. Furthermore, overexpression of Bim(EL) triggered apoptosis in granulosa cells. In primary granulosa cell cultures under basal conditions, we observed that Bim(EL) expression was dampened by treatment with follicle-stimulating hormone (FSH). The role of the PI3K/Akt pathway in the regulation of repression was clarified by the use of the PI3K inhibitor, LY294002, and by transfection with Akt siRNA. Forkhead Box Protein O3a (FoxO3a), a well defined transcriptional activator of Bim, was phosphorylated at Ser-253 and inactivated after FSH stimulation. Also, FSH abolished FoxO3a nuclear accumulation in response to LY294002. Finally, chromatin immunoprecipitation assays demonstrated that FoxO3a directly bound and activated the bim promoter. Taken together, we conclude that Bim(EL) induces porcine granulosa cell apoptosis during follicular atresia, and its expression is regulated by FSH via the PI3K/Akt/FoxO3a pathway.
authors.affiliation: Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing 100193 and.
authors.forename: Xian-Long
authors.initials: XL
authors.lastname: Wang
authors.affiliation: Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing 100193 and.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing 100193 and.
authors.forename: Lu-Bin
authors.initials: LB
authors.lastname: Tan
authors.affiliation: Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing 100193 and.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Tian
authors.affiliation: Laboratory Animal Centre, Peking University, Beijing 100871, China.
authors.forename: Jing-Hao
authors.initials: JH
authors.lastname: Liu
authors.affiliation: Laboratory Animal Centre, Peking University, Beijing 100871, China.
authors.forename: De-Sheng
authors.initials: DS
authors.lastname: Zhu
authors.affiliation: Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing 100193 and. Electronic address: zengsm@cau.edu.cn.
authors.forename: Shen-Ming
authors.initials: SM
authors.lastname: Zeng
mesh_terms: D017398:Alternative Splicing / Q000187:drug effects / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D000072224:Bcl-2-Like Protein 11; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006107:Granulosa Cells / Q000166:cytology / Q000378:metabolism*; D006728:Hormones / Q000494:pharmacology*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D020033:Protein Isoforms / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology; D013552:Swine
chemical_list: D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D002867:Chromones; D004791:Enzyme Inhibitors; D005640:Follicle Stimulating Hormone; D051858:Forkhead Transcription Factors; D006728:Hormones; D008565:Membrane Proteins; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; C000606775:BCL2L11 protein, human; C000606776:Bcl2l11 protein, mouse; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one