Global downstream BMP15 pathway analysis in human ovarian granulosa cells reveals novel genetic variations associated with primary ovarian insufficiency.
OBJECTIVES: Primary ovarian insufficiency (POI) is a fertility disorder with a well-established genetic component, but many cases still remain idiopathic. Approximately 1.5-12% of patients with POI can carry a variant in the BMP15 gene, depending on the population and the diagnostic criteria. We hypothesize that genetic variations within pathways downstream of BMP15 activity in ovarian granulosa cells (GCs) may contribute to unexplained cases of POI. The main goal of this study is to identify novel variants associated with POI in genes induced by BMP15 in GCs. STUDY DESIGN: Primary cultures of human GCs were stimulated with recombinant human BMP15. Microarray analysis profiled the BMP15-induced transcriptome in GCs. Validation was achieved by qPCR and immunoblot. Further, target exome sequencing of the differentially expressed genes was performed on 64 women with early POI onset in search of novel variants. MAIN OUTCOME MEASURES: Transcriptome profiling of human GCs stimulated with BMP15 and target exome sequencing in women with early onset of POI. RESULTS: Transcriptome analysis revealed significant upregulation of 19 genes (p < 0.05). Ontology analysis of these genes converged towards two main pathways: TGF-beta signaling and regulation of stem cell pluripotency. Target exome sequencing identified six novel rare variants in five BMP15-induced genes (SAMD11, SMAD6, ID1, USP35, GPCR137C) in 9 of the 64 women with early POI (14%). CONCLUSIONS: BMP15 action in human ovarian GCs defines TGF-beta signaling and pluripotency fate in ovarian follicles. In addition, this study uncovers new potential candidate genes for the pathogenesis of POI.