Bone Morphogenetic Protein-15

Abstract

In developing ovarian follicles, the regulation of cell proliferation and differentiation is tightly coordinated. Precisely how this coordination is achieved is unknown, but recent observations have suggested that molecules emitted by the oocyte are involved in the process. The newly discovered oocyte-specific growth factor, bone morphogenetic protein-15 (BMP-15), is one such molecule. At present, nothing is known about the target cells and biological functions of BMP-15. To fill this gap in our knowledge, recombinant BMP-15 and its antibody were produced and used to determine BMP-15 expression and bioactivity. BMP-15 mRNA and protein were shown to be co-expressed in oocytes throughout folliculogenesis, supporting the idea that BMP-15 is a physiological regulator of follicle cell proliferation and/or differentiation. To test this, we used primary cultures of rat granulosa cells (GCs). We found that BMP-15 is a potent stimulator of GC proliferation, and importantly, the mitogenic effect was follicle-stimulating hormone (FSH)-independent. By contrast, BMP-15 alone had no effect on steroidogenesis. However, it produced a marked decrease in FSH-induced progesterone production, but had no effect on FSH-stimulated estradiol production. This result indicates that BMP-15 is a selective modulator of FSH action. In summary, this study identifies GCs as the first target cells for BMP-15. Moreover, it identifies the stimulation of GC proliferation and the differential regulation of two crucial steroid hormones as the first biological functions of BMP-15. Significantly, BMP-15 is the first growth factor that can coordinate GC proliferation and differentiation in a way that reflects normal physiology.

Effect of Intracellular Interactions on the Processing and Secretion of Bone Morphogenetic Protein-15 (BMP-15) and Growth and Differentiation Factor-9

“…1). Both cell lines that were transfected with phBMP-15F or with phBMP-15F/hGDF-9M secreted BMP-15 which was detected with the anti-FLAG Ab as three bands: the proprotein detected at ϳ50 kDa and two bands of the mature protein detected at 16 and 17 kDa as previously reported (12). On the other hand, the GDF-9 and the BMP-15/GDF-9 cell lines both secreted GDF-9, with the proprotein migrating at ϳ70 kDa and mature GDF-9 migrating at ϳ20 kDa.…”

“…The GDF-9 cDNA with the Myc tag was then released by digestion with NotI and KpnI, subcloned into one of the multiple cloning sites of a dual expression vector, pBudCE4.1 (Invitrogen), to form a plasmid designated as phGDF-9M. Human BMP-15 cDNA fused with a FLAG epitope tag was released from the previously constructed phBMP-15-FLAG (12) by digestion with SacII and PacI, blunt-ended with T4 DNA polymerase and subcloned into the ScaI site of the other multiple cloning site of phGDF-9M. The resulting plasmid, designated as phBMP-15F/hGDF-9M, contains the full structure of human BMP-15 tagged with a FLAG epitope under the control of the cytomegalovirus promoter and human GDF-9 tagged with a c-Myc epitope under the control of the EF-1␣ promoter.…”

“…Based on our previous findings on the in vitro biological effects of recombinant BMP-15, we have presented a model by which the levels of bioactive BMP-15 may account for the divergent phenotypes of the heterozygous and homozygous Inverdale ewes (12,26,27). In the heterozygotes of Inverdale ewes, the reduced level of bioactive BMP-15 results in higher levels of follicle-stimulating hormone (FSH) receptor in the granulosa cells which in turn leads to more developing healthy follicles with more luteinizing hormone (LH) receptors, resulting in precocious follicle growth and increased ovulation at earlier stages of follicular development.…”

Bone morphogenetic protein (BMP) ligands and receptors in bovine ovarian follicle cells: actions of BMP-4, -6 and -7 on granulosa cells and differential modulation of Smad-1 phosphorylation by follistatin

“…The Booroola phenotype is caused by a mutation in the BMPRIB gene, which results in increased ovulation rate and multiple births (Souza et al 2001. Taken together with recent in vitro studies on the effects of BMPs on rat ovarian cell steroidogenesis (Otsuka et al 2000, 2001a,b, Lee et al 2001, such evidence points to the BMP system as having a major regulatory role in the mammalian ovary, central to follicular recruitment and selection mechanisms. However, little is known about the interplay between the BMPs and other welldocumented intraovarian factors implicated in follicle regulation including insulin-like growth factors (IGF), inhibin-A, activin-A and follistatin (FS) (Adashi et al 1992, Webb et al 1999).…”

BMP2, 4 and 6 and BMPR1B are altered from early stages of bovine cystic ovarian disease development

“…The Booroola phenotype is caused by a mutation in the BMP receptor 1B (BMPR1B) gene, which results in an increased ovulation rate and multiple births (Souza et al 2001, Wilson et al 2001, whereas the Inverdale phenotype arises from a mutation in the BMP15 gene (Galloway et al 2000), where homozygous inactivating mutations in BMP15 and GDF9 genes impair preantral follicle development, causing sterility (Liao et al 2003). These results, together with in vitro studies on the effects of BMPs on ovarian cell steroidogenesis (Otsuka et al 2000(Otsuka et al , 2001(Otsuka et al , 2013, point to the BMP system as having a major regulatory role in the mammalian ovary, central to follicular recruitment and selection mechanisms (Glister et al 2004). In this sense, BMPs play multiple roles in the regulation of growth, differentiation and apoptosis of numerous cell types.…”