Modulatory effects of TGF-β1 and BMP6 on thecal angiogenesis and steroidogenesis in the bovine ovary. Issue 4 (April 2020)

• Record Type: Journal Article
• Authors: Mattar, D; Samir, M; Laird, M; Knight, P G
• Is Part Of: Reproduction. Volume 159:Issue 4(2020)
• Page Start: 397
• Page End: 408
• Publication Date: 2020-04
• Subjects: Reproduction -- Periodicals; Reproduction -- Molecular aspects -- Periodicals; Reproduction -- Immunological aspects -- Periodicals; Reproduction -- Endocrine aspects -- Periodicals; Fertility -- Periodicals; Human reproduction -- Periodicals; 571.805
• DOI: 10.1530/REP-19-0311
• Languages: English
• ISSNs: 1470-1626

Abstract

Abstract : Angiogenesis plays an integral role in follicular and luteal development and is positively regulated by several intra-ovarian factors including vascular endothelial growth factor A (VEGFA) and fibroblast growth factor 2 (FGF2). Various transforming growth factor-β (TGF-β) superfamily members function as intra-ovarian regulators of follicle and luteal function, but their potential roles in modulating ovarian angiogenesis have received little attention. In this study, we used a bovine theca interna culture model (exhibiting characteristics of luteinization) to examine the effects of TGF-β1 and bone morphogenetic protein 6 (BMP6) on angiogenesis and steroidogenesis. VEGFA/FGF2 treatment promoted endothelial cell network formation but had little or no effect on progesterone and androstenedione secretion or expression of key steroidogenesis-related genes. TGF-β1 suppressed basal and VEGFA/FGF2-induced endothelial cell network formation and progesterone secretion, effects that were reversed by an activin receptor-like kinase 5 (ALK5) inhibitor (SB-431542). The ALK5 inhibitor alone raised androstenedione secretion and expression of several transcripts including CYP17A1 . BMP6 also suppressed endothelial cell network formation under VEGFA/FGF2-stimulated conditions and inhibited progesterone secretion and expression of several steroidogenesis-related genes under basal and VEGFA/FGF2-stimulated conditions. These effects were reversed by an ALK1/2 inhibitor (K02288). Moreover, the ALK1/2 inhibitor alone augmented endothelial network formation, progesterone secretion, androstenedione secretion and expression of several steroidogenesis-related genes. The results indicate dual suppressive actions of both TGF-β1 and BMP6 on follicular angiogenesis and steroidogenesis. Further experiments are needed to unravel the complex interactions between TGF-β superfamily signalling and other regulatory factors controlling ovarian angiogenesis and steroidogenesis.