The Role of Bone Morphogenetic Protein-4 in Mammalian Reproduction

Abstract

The BMPs comprise the largest subgroup of the TGF-β superfamily. Various members of the BMP family have been shown to regulate mammalian folliculogenesis by affecting granulosa cell proliferation, steroidogenesis and by modulating the production of various endocrine factors such as activin A, follistatin, inhibin, estradiol and progesterone. 'In situ' hybridization studies have shown expression of BMPR-IA, BMPR-IB and BMPRII in the granulosa cells and oocyte of most of the follicles in the ovary suggesting that these cells have capacity to respond to BMP signaling. In addition, the mRNA for BMP-4 and BMP-7 has been in detected in the theca layer of rat follicles. In 'in vitro' conditions, physiological concentrations of BMP-4 and BMP-7 enhanced and attenuated respectively,the stimulatory action of FSH on estradiol and progesterone production. The objective of the current study was to elucidate the role of BMP-4 in mammalian follicular development and spermatogenesis by using mouse and sheep as experimental models.