GDF9 and BMP15: species difference and synergistic interactions.

GDF9 and BMP15 are two oocyte-secreted proteins which have been shown to be essential for normal mammalian fertility. There are a number of factors which impact their efficiency, including species difference of the proteins, GDF9/BMP15 interactions and the presence of post-translational modifications. However, factors such as species difference and post-translational modifications have yet to be investigated in terms of their effects on GDF9/BMP15 interactions. The aims of this study were to produce well purified human and mouse GDF9 and human BMP15 to test the effects of these factors. We found clear species differences between mouse and human GDF9 in thymidine incorporation in mouse and bovine granulosa cells. However, not only did we find a species difference due to the species of the protein, but also a difference due to the species of the cells on which the proteins were acting. GDF9 and BMP15 were found to interact synergistically on mouse granulosa cells, but not on bovine cells. Human GDF9 was found to be dependent on the presence of BMP15 for bioactivity in both species of cell however, the introduction of mouse-like residues into the human GDF9 sequence was able to produce a protein capable of functioning independent of BMP15 and with even higher bioactivity than wild-type mouse GDF9. Post-translational modifications were also found to have significant effects on synergistic GDF9/BMP15 synergistic interactions. Both GDF9 and BMP15 have previously been shown to be phosphorylated. This appears to be more important to the correct functioning of GDF9. Loss of GDF9 phosphorylation was found not only to decrease its bioactivity but also to decrease its synergistic interactions with BMP15. Phosphorylation was not found to affect BMP15 however; the loss of o-linked glycosylation decreased its ability to synergise with GDF9. To fully assess the implications and applications of this work, there is still a great deal of work to be done however, it is clear that for any embryological studies, the species differences of the proteins and cells need to be carefully considered.

Author dc:creator

• Martin, Georgia Alice

Advisors dc:contributor.advisor

• Mottershead, David Gregory
• Gilchrist, Robert Bruce

• GDF9; BMP15; TGF-β; synergism; species difference; oocyte-secreted; growth factor

Handle dc:identifier.uri

http://hdl.handle.net/2440/87852

OAI identifier oai:identifier

oai:digital.library.adelaide.edu.au:2440/87852