Endogenous inhibins regulate steroidogenesis in mouse TM3 Leydig cells by altering SMAD2 signalling. (15th November 2016)

• Record Type: Journal Article
• Authors: Wang, Yao; Bilandzic, Maree; Ooi, Guck T.; Findlay, Jock K.; Stenvers, Kaye L.
• Is Part Of: Molecular and cellular endocrinology. Volume 436(2016)
• Page Start: 68
• Page End: 77
• Publication Date: 2016-11-15
• Subjects: TM3 cells -- Inha knockdown -- Steroidogenesis -- SMAD2 -- Leydig; Endocrinology -- Periodicals; Molecular biology -- Periodicals; Cytology -- Periodicals; Endocrinology -- Periodicals; Hormones -- Periodicals; Endocrinologie -- Périodiques; Cytology; Endocrinology; Molecular biology; Periodicals; 573.4
• DOI: 10.1016/j.mce.2016.07.026
• Languages: English
• ISSNs: 0303-7207

Abstract

Abstract: This study tested the hypothesis that inhibins act in an autocrine manner on Leydig cells using a pre-pubertal Leydig cell line, TM3, as a model of immature Leydig cells. The expression of Inha, Inhba, and Inhbb in TM3 cells was determined by RT-PCR and the production of the inhibin-alpha subunit was confirmed by western blot. Knockdown of Inha expression resulted in significant decreases in the expression of Leydig cell markers Cyp17a1, Cyp11a1, Nr5a1, and Insl3 . Western blot showed that activin A, TGFβ1 and TGFβ2 activated SMAD2, and that knockdown of Inha expression in TM3 cells enhanced both activin A- and TGFβ-induced SMAD2 activation. SB431542, a chemical inhibitor of the TGFβ/activin type I receptors, blocked ligand-induced SMAD2 activation and the downregulation of Cyp17a1 expression. Our findings demonstrate that TGFβs and activin A negatively regulate steroidogenic gene expression in TM3 cells via ALK4/5 and SMAD2 and endogenous inhibins can counter this regulation. Highlights: Activin A, TGFβ1 and TGFβ2 all downregulated Inha mRNA expression in TM3 cells. Knockdown of Inha gene negatively regulated steroidogenesis in TM3 cells. TGFβs and activin A signalled via the activation of ALK4/5 and SMAD2 in TM3 cells. Inha knockdown enhanced activin and TGFβ-stimulated SMAD2 activation in TM3 cells. Inha expression in Leydig cells is essential for steroidogenesis.