Anti-Müllerian hormone induces autophagy to preserve the primordial follicle pool in mice.

The reserve pool of primordial follicles (PMFs) is finely regulated by molecules implicated in follicular growth or PMF survival. Anti-Müllerian hormone (AMH), produced by granulosa cells of growing follicles, is known for its inhibitory role in the initiation of PMF growth. We observed in a recent in vivo study that injection of AMH into mice seemed to induce an activation of autophagy. Furthermore, injection of AMH into mice activates the transcription factor FOXO3A which is also known for its implication in autophagy regulation. Many studies highlighted the key role of autophagy in the ovary at different stages of folliculogenesis, particularly in PMF survival. Through an in vitro approach with organotypic cultures of prepubertal mouse ovaries, treated or not with AMH, we aimed to understand the link among AMH, autophagy, and FOXO3A transcription factor. Autophagy and FOXO3A phosphorylation were analyzed by western blot. The expression of genes involved in autophagy was quantified by RT-qPCR. In our in vitro model, we confirmed the decrease in FOXO3A phosphorylation and the induction of autophagy in ovaries incubated with AMH. AMH also induces the expression of genes involved in autophagy. Interestingly, most of these genes are known to be FOXO3A target genes. In conclusion, we have identified a new role for AMH, namely the induction of autophagy, probably through FOXO3A activation. Thus, AMH protects the ovarian reserve not only by inhibiting the growth of PMFs but also by enabling their survival through activation of autophagy.

ATG7 and ATG9A loss-of-function variants trigger autophagy impairment and ovarian failure.

PURPOSE: Primary ovarian insufficiency (POI) is a frequent disorder that affects ~1% of women under 40 years of age. POI, which is characterized by the premature depletion of ovarian follicles and elevated plasma levels of follicle-stimulating hormone (FSH), leads to infertility. Although various etiological factors have been described, including chromosomal abnormalities and gene variants, most cases remain idiopathic. The aim of the present study was to identify and validate functionally new sequence variants in ATG (autophagy-related genes) leading to POI. METHODS: We have reanalyzed, in silico, the exome sequencing data from a previously reported work performed in 69 unrelated POI women. Functional experiments using a classical hallmark of autophagy, the microtubule-associated protein 1 light chain 3ß (LC3), were then used to link these genes to this lysosomal degradation pathway. RESULTS: We venture a functional link between ATG7 and ATG9A variants and POI. We demonstrated that variant ATG7 and ATG9A led to a decrease in autophagosome biosynthesis and consequently to an impairment of autophagy, a key biological process implicated in the preservation of the primordial follicles forming the ovarian reserve. CONCLUSION: Our results unveil that impaired autophagy is a novel pathophysiological mechanism involved in human POI.

BMPR1A and BMPR1B Missense Mutations Cause Primary Ovarian Insufficiency.

CONTEXT: Primary ovarian insufficiency (POI) is a frequently occurring disorder affecting approximately 1% of women under 40 years of age. POI, which is characterized by the premature depletion of ovarian follicles and elevated plasma levels of follicle-stimulating hormone, leads to infertility. Although various etiological factors have been described, including chromosomal abnormalities and gene mutations, most cases remain idiopathic. OBJECTIVE: To identify and to functionally validate new sequence variants in 2 genes that play a key role in mammalian ovarian function, BMPR1A and BMPR1B (encoding for bone morphogenic protein receptor), leading to POI. METHODS: The impact on bone morphogenic protein (BMP) signaling of BMPR1A and BMPR1B variants, previously identified by whole-exome sequencing on 69 women affected by isolated POI, was established by different in vitro functional experiments. RESULTS: We demonstrate that the BMPR1A-p.Arg442His and BMPR1B-p.Phe272Leu variants are correctly expressed and located but lead to an impairment of downstream BMP signaling. CONCLUSION: In accordance with infertility observed in mice lacking Bmpr1a in the ovaries and in Bmpr1b-/- mice, our results unveil, for the first time, a link between BMPR1A and BMPR1B variants and the origin of POI. We show that BMP signaling impairment through specific BMPR1A and BMPR1B variants is a novel pathophysiological mechanism involved in human POI. We consider that BMPR1A and BMPR1B variants constitute genetic biomarkers of the origin of POI and have clinical utility.