The Joint Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology 2018

The oocyte-secreted factors GDF9, BMP15 and cumulin regulate inhibin and activin production in human granulosa cells (#27)

Dulama Richani 1 , Katherine Constance 1 , Shelly Lien 1 , David Agapiou 1 , William Stocker 2 , Mark Hedger 3 , William Ledger 1 , Jeremy Thompson 4 , David Robertson 1 , David Mottershead 4 5 , Craig Harrison 2 , Kelly Walton 2 , Robert Gilchrist 1
  1. School of Women's and Children's Health, UNSW Sydney, Kensington, NSW, Australia
  2. Biomedicine Discovery Institute, Department of Physiology, Monash University, Clayton, VIC, Australia
  3. Centre for Reproductive Health, Hudson Institute of Medical Research, Clayton, VIC, Australia
  4. Robinson Research Institute, Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
  5. Institute for Science and Technology in Medicine, School of Pharmacy, Keele University, Newcastle-under-Lyme, UK

The oocyte-secreted factors bone morphogenetic protein 15 (BMP15) and growth differentiation factor 9 (GDF9) regulate folliculogenesis, oocyte quality and fecundity. They are comprised of a pro-domain and a mature domain and it is known the pro-proteins are biologically active on cumulus cells. In addition, there is evidence that GDF9 and BMP15 can form a potent heterodimer called cumulin. This study utilized various recombinant forms of GDF9, BMP15 and cumulin to assess the effect of; 1) homo- versus hetero-dimer proteins and, 2) pro-mature versus mature forms of proteins, on primary human granulosa-lutein cell function. Cells were treated in vitro with GDF9, BMP15, or cumulin ± their pro-domains; mRNA expression and protein secretion of inhibin A and B and activin B were measured. Regardless of whether cells were treated with mature- or pro-forms, GDF9 or BMP15 alone exhibited minimal effects on inhibin/activin production, whereas the addition of both factors elicited a marked synergistic increase in INHβB mRNA and protein production of inhibin B and activin B, but not inhibin A. Consistent with the hypothesis GDF9-BMP15 synergism is due to the actions of cumulin, both mature cumulin and pro-cumulin dose-dependently increased INHβB mRNA expression and inhibin B and activin B production, but not inhibin A. FSH induced expression of INHα mRNA expression leading to a 2- to 3-fold increase in inhibin B production when co-treated with GDF9+BMP15 or cumulin, and a corresponding decrease in activin B production. In general proteins in the pro-form and those lacking the pro-domain elicited the same effect on inhibin/ activin production, suggesting that the pro-domain may have a minimal role in the actions of these growth factors on granulosa cells. In conclusion, oocyte-secreted GDF9 and BMP15, likely in the form of the heterodimer cumulin, exert paracrine control of gonadotrophin-induced production of inhibin B/activin B in follicular granulosa cells.