title: Growth Differentiation Factor-8 Decreases StAR Expression Through ALK5-Mediated Smad3 and ERK1/2 Signaling Pathways in Luteinized Human Granulosa Cells.
abstract: Growth differentiation factor-8 (GDF-8) has been recently shown to be expressed in human granulosa cells, and the mature form of GDF-8 protein can be detected in the follicular fluid. However, the biological function and significance of this growth factor in the human ovary remains to be determined. Here, we investigated the effects of GDF-8 on steroidogenic enzyme expression and the potential mechanisms of action in luteinized human granulosa cells. We demonstrated that treatment with GDF-8 did not affect the mRNA levels of P450 side-chain cleavage enzyme and 3β-hydroxysteroid dehydrogenase, whereas it significantly down-regulated steroidogenic acute regulatory protein (StAR) expression and decreased progesterone production. The suppressive effect of GDF-8 on StAR expression was abolished by the inhibition of the TGF-β type I receptor. In addition, treatment with GDF-8 activated both Smad2/3 and ERK1/2 signaling pathways. Furthermore, knockdown of activin receptor-like kinase 5 reversed the effects of GDF-8 on Smad2/3 phosphorylation and StAR expression. The inhibition of Smad3 or ERK1/2 signaling pathways attenuated the GDF-8-induced down-regulation of StAR and production of progesterone. Interestingly, the concentrations of GDF-8 were negatively correlated with those of progesterone in human follicular fluid. These results indicate a novel autocrine function of GDF-8 to down-regulate StAR expression and decrease progesterone production in luteinized human granulosa cells, most likely through activin receptor-like kinase 5-mediated Smad3 and ERK1/2 signaling pathways. Our findings suggest that granulosa cells might play a critical role in the regulation of progesterone production to prevent premature luteinization during the final stage of folliculogenesis.
authors.affiliation: Reproductive Medical Center (L.F., Y.Y., Y.-P.S.), The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China 450052; and Department of Obstetrics and Gynaecology (H.-M.C., J.-C.C., P.C.K.L.), Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4.
authors.forename: Lanlan
authors.initials: L
authors.lastname: Fang
authors.affiliation: Reproductive Medical Center (L.F., Y.Y., Y.-P.S.), The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China 450052; and Department of Obstetrics and Gynaecology (H.-M.C., J.-C.C., P.C.K.L.), Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4.
authors.forename: Hsun-Ming
authors.initials: HM
authors.lastname: Chang
authors.affiliation: Reproductive Medical Center (L.F., Y.Y., Y.-P.S.), The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China 450052; and Department of Obstetrics and Gynaecology (H.-M.C., J.-C.C., P.C.K.L.), Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4.
authors.forename: Jung-Chien
authors.initials: JC
authors.lastname: Cheng
authors.affiliation: Reproductive Medical Center (L.F., Y.Y., Y.-P.S.), The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China 450052; and Department of Obstetrics and Gynaecology (H.-M.C., J.-C.C., P.C.K.L.), Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Reproductive Medical Center (L.F., Y.Y., Y.-P.S.), The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China 450052; and Department of Obstetrics and Gynaecology (H.-M.C., J.-C.C., P.C.K.L.), Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4.
authors.forename: Peter C K
authors.initials: PC
authors.lastname: Leung
authors.affiliation: Reproductive Medical Center (L.F., Y.Y., Y.-P.S.), The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China 450052; and Department of Obstetrics and Gynaecology (H.-M.C., J.-C.C., P.C.K.L.), Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4.
authors.forename: Ying-Pu
authors.initials: YP
authors.lastname: Sun
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D015536:Down-Regulation; D005260:Female; D015571:Follicular Fluid / Q000737:chemistry; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D034461:Luteinization; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D055435:Myostatin / Q000494:pharmacology*; D010750:Phosphoproteins / Q000187:drug effects / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D011374:Progesterone / Q000096:biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects* / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism; D015398:Signal Transduction; D051899:Smad2 Protein / Q000187:drug effects / Q000378:metabolism; D051900:Smad3 Protein / Q000187:drug effects* / Q000378:metabolism; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D055435:Myostatin; D010750:Phosphoproteins; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein; D000098682:Steroidogenic Acute Regulatory Protein; D011374:Progesterone; D015096:3-Hydroxysteroid Dehydrogenases; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625841:TGFBR1 protein, human