A variant of human growth differentiation factor-9 that improves oocyte developmental competence

Abstract

Growth differentiation factor-9 (GDF9) and bone morphogenetic protein-15 (BMP15) are co-expressed exclusively in oocytes throughout most of folliculogenesis and play central roles in controlling ovarian physiology. Although both growth factors exist as homodimers, recent evidence indicates that GDF9 and BMP15 can also heterodimerize to form the potent growth factor cumulin. Within the cumulin complex, BMP15 “activates” latent GDF9, enabling potent signaling in granulosa cells via type I receptors (i.e. activin receptor-like kinase-4/5 (ALK4/5)) and SMAD2/3 transcription factors. In the cumulin heterodimer, two distinct type I receptor interfaces are formed compared with homodimeric GDF9 and BMP15. Previous studies have highlighted the potential of cumulin to improve treatment of female infertility, but, as a noncovalent heterodimer, cumulin is difficult to produce and purify without contaminating GDF9 and BMP15 homodimers. In this study we addressed this challenge by focusing on the cumulin interface formed by the helix of the GDF9 chain and the fingers of the BMP15 chain. We demonstrate that unique BMP15 finger residues at this site (Arg301, Gly304, His307, and Met369) enable potent activation of the SMAD2/3 pathway. Incorporating these BMP15 residues into latent GDF9 generated a highly potent growth factor, called hereafter Super-GDF9. Super-GDF9 was >1000-fold more potent than WT human GDF9 and 4-fold more potent than cumulin in SMAD2/3-responsive transcriptional assays in granulosa cells. Our demonstration that Super-GDF9 can effectively promote mouse cumulus cell expansion and improve oocyte quality in vitro represents a potential solution to the current challenges of producing and purifying intact cumulin.

Phycocyanin Improves Reproductive Ability in Obese Female Mice by Restoring Ovary and Oocyte Quality

“…As obesity led to an increase in the number of atretic follicles, we wondered if this increase was induced by the abnormal expressions of the genes BMP4, GDF9, or LHX8 that play key roles during ovarian follicular development (Fu et al, 2017;Liu et al, 2017;Stocker et al, 2020). Our results demonstrated that there were no significant differences in their mRNA expression levels among the three mice groups, suggesting that the increased number of atretic follicles was not caused by abnormal BMP, GDF9, and LHX8 gene expression.…”

Intrafollicular Concentrations of the Oocyte-secreted Factors GDF9 and BMP15 Vary Inversely in Polycystic Ovaries

“…However, to date, it is still unknown whether this cooperation is generated by GDF9 and BMP15 homodimers separately or by the GDF9/BMP15 heterodimer. Interestingly, in vitro studies have shown that the recombinant human GDF9/BMP15 heterodimer potently activates Smad2/3 signalling in mammalian granulosa cells and improve embryo development during oocyte in vitro maturation compared to human GDF9 and BMP15 homodimers ( 29 , 30 , 59 ). However, our current findings indicate similar intrafollicular concentrations of the GDF9/BMP15 heterodimer and BMP15 in small antral follicles, suggesting that only a minor proportion of the total GDF9 would potentially form a heterodimer with BMP15 in vivo, and that GDF9 performs actions on its own as a homodimer.…”

Polymorphism Detection of GDF9 Gene and Its Association with Litter Size in Luzhong Mutton Sheep (Ovis aries)

“…GDF9 plays an important role in controlling ovarian physiology and enhancing oocyte developmental competence [ 41 ]. The GDF9 mutation can affect the fertility and sterility by producing different effects on number of follicles and oocyte in ewes [ 1 ].…”