title: Functional link between bone morphogenetic proteins and insulin-like peptide 3 signaling in modulating ovarian androgen production.
abstract: Bone morphogenetic proteins (BMPs) are firmly implicated as intra-ovarian regulators of follicle development and steroidogenesis. Here we report a microarray analysis showing that treatment of cultured bovine theca cells (TC) with BMP6 significantly (>twofold; P < 0.01) up- or down-regulated expression of 445 genes. Insulin-like peptide 3 (INSL3) was the most heavily down-regulated gene (-43-fold) with cytochrome P450, subfamily XVII (CYP17A1) and other key steroidogenic transcripts including steroidogenic acute regulatory protein (STAR), cytochrome P450 family 11, subfamily A1 (CYP11A1) and 3 beta-hydroxysteroid dehydrogenase type 1 (HSD3B1) also down-regulated. BMP6 also reduced expression of nuclear receptor subfamily 5A1 (NR5A1) known to target the promoter regions of the aforementioned genes. Real-time PCR confirmed these findings and also revealed a marked reduction in expression of INSL3 receptor, relaxin/insulin-like family peptide receptor 2 (RXFP2). Secretion of INSL3 protein and androstenedione were also suppressed suggesting a functional link between BMP and INSL3 pathways in controlling androgen synthesis. RNAi-mediated knockdown of INSL3 reduced INSL3 mRNA (75%) and protein (94%) level and elicited a 77% reduction in CYP17A1 mRNA and 83% reduction in androstenedione secretion. Knockdown of RXFP2 also reduced CYP17A1 expression (81%) and androstenedione secretion (88%). Conversely, treatment with exogenous (human) INSL3 increased androstenedione secretion ∼twofold. The CYP17A1 inhibitor abiraterone abolished androgen secretion and reduced expression of both INSL3 and RXFP2. Collectively, these findings indicate a positive autoregulatory role for INSL3 signaling in maintaining thecal androgen production, and visa versa. Moreover, BMP6-induced suppression of thecal androgen synthesis may be mediated, at least in part, by reduced INSL3-RXFP2 signaling.
authors.affiliation: School of Biological Sciences, University of Reading, Reading RG6 6UB, United Kingdom.
authors.forename: Claire
authors.initials: C
authors.lastname: Glister
authors.forename: Leanne
authors.initials: L
authors.lastname: Satchell
authors.forename: Ross A D
authors.initials: RA
authors.lastname: Bathgate
authors.forename: John D
authors.initials: JD
authors.lastname: Wade
authors.forename: Yanzhenzi
authors.initials: Y
authors.lastname: Dai
authors.forename: Richard
authors.initials: R
authors.lastname: Ivell
authors.forename: Ravinder
authors.initials: R
authors.lastname: Anand-Ivell
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Rodgers
authors.forename: Philip G
authors.initials: PG
authors.lastname: Knight
mesh_terms: D000728:Androgens / Q000378:metabolism*; D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D016000:Cluster Analysis; D004815:Epidermal Growth Factor / Q000378:metabolism; D005260:Female; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D008957:Models, Genetic; D020411:Oligonucleotide Array Sequence Analysis; D010053:Ovary / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D011506:Proteins / Q000378:metabolism*; D015398:Signal Transduction; D013254:Steroid 17-alpha-Hydroxylase / Q000378:metabolism; D054339:Steroidogenic Factor 1 / Q000378:metabolism; D013799:Theca Cells / Q000166:cytology; D016211:Transforming Growth Factor alpha / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000728:Androgens; D019485:Bone Morphogenetic Proteins; D007328:Insulin; C084797:Leydig insulin-like protein; D011506:Proteins; D054339:Steroidogenic Factor 1; D016211:Transforming Growth Factor alpha; D014409:Tumor Necrosis Factor-alpha; D004815:Epidermal Growth Factor; D013254:Steroid 17-alpha-Hydroxylase