Effect of intracellular interactions on the processing and secretion of bone morphogenetic protein-15 (BMP-15) and growth and differentiation factor-9: Implication of the aberrant ovarian phenotype of BMP-15 mutant sheep

Wu Xiang Liao, R. Kelly Moore, Fumio Otsuka, Shunichi Shimasaki

Research output: Contribution to journalArticle

125 Citations (Scopus)

Abstract

Bone morphogenetic protein-15 (BMP-15) and growth and differentiation factor-9 (GDF-9) are members of the transforming growth factor-β superfamily. Both molecules are closely related in their primary structures and share a nearly identical spatiotemporal expression pattern in the oocyte during folliculogenesis in mammals. Here we have established a series of cell lines, which express recombinant BMP-15, GDF-9, or both, and investigated whether they form homodimers and/or heterodimers. We demonstrate the first evidence that both BMP-15 and GDF-9 can form non-covalent homodimers when expressed individually, while when both are coexpressed BMP-15/GDF-9 heterodimers are produced. Interestingly, when GDF-9 and BMP-15 are co-expressed the processing of both proproteins are significantly impaired as compared with that of the singly expressed proproteins, suggesting that the proprotein heterodimer is less susceptible to proteolytic cleavage than the individual homodimers. Since BMP-15 mutant sheep, called Inverdale, exhibit severe defects in ovarian function we have also established stable transformants expressing the mutant BMP-15 (InvBMP-15) alone or together with GDF-9. Although InvBMP-15 was previously predicted to be unable to form homodimers, we show here that it does form non-covalent dimers; however, the processing efficiency of InvBMP-15 proprotein is significantly lower than wild-type BMP-15. Surprisingly, when GDF-9 is co-expressed, the processing and secretion of InvBMP-15 is abolished, and the processing of GDF-9 is also severely impaired, suggesting that the heterodimers of InvBMP-15/GDF-9 proproteins are not susceptible to proteolytic cleavage and thus degrade in the cells. Based on these findings we propose a novel hypothesis that a decrease in GDF-9 secretion may be involved in causing infertility in homozygous Inverdale ewes.

Original languageEnglish
Pages (from-to)3713-3719
Number of pages7
JournalJournal of Biological Chemistry
Volume278
Issue number6
DOIs
Publication statusPublished - Feb 7 2003
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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