The genetic etiology of premature ovarian insufficiency (POI) has been well established to date, however, the role of long noncoding RNAs (lncRNAs) in POI is largely unknown. In this study, we identified a down-expressed lncRNA HCP5 in granulosa cells (GCs) from biochemical POI (bPOI) patients, which impaired DNA damage repair and promoted apoptosis of GCs. Mechanistically, we discovered that HCP5 stabilized the interaction between YB1 and its partner ILF2, which could mediate YB1 transferring into the nucleus of GCs. HCP5 silencing affected the localization of YB1 into nucleus and reduced the binding of YB1 to the promoter of MSH5 gene, thereby diminishing MSH5 expression. Taken together, we identified that the decreased expression of HCP5 in bPOI contributed to dysfunctional GCs by regulating MSH5 transcription and DNA damage repair via the interaction with YB1, providing a novel epigenetic mechanism for POI pathogenesis.

Granulosa cell (GC) is a critical somatic component of ovarian follicles to support oocyte development, while the regulatory role of long noncoding RNA (lncRNA) in GCs is largely unknown. Here, we identified a down-regulated lncRNA ZNF674-AS1 in GCs from patients with biochemical premature ovarian insufficiency (bPOI), and its expression correlates with serum levels of clinical ovarian reserve indicators. Functional experiments showed that ZNF674-AS1 is induced by energy stress, and regulates the proliferation and glycolysis of GCs, which possibly leads to follicular dysfunction. Mechanistically, low-expressed ZNF674-AS1 reduced the enzymatic activity of aldolase A (ALDOA), concomitant with promoting the association between ALDOA and v-ATPase to activate the lysosome localized AMP-activated protein kinase (AMPK). These findings identified a new lncRNA–ALDOA complex through which ZNF674-AS1 exerts its functions, expanding the understanding of epigenetic regulation of GCs function and POI pathogenesis.

Dysfunction of granulosa cells (GCs) leading to follicle atresia has been extensively studied as a major cause of premature ovarian insufficiency (POI), but the regulatory role of long non-coding RNAs (lncRNAs) in this process is still poorly understood. Here, we show that the lncRNA LINC02690 or GCAT1 (granulosa cell-associated transcript 1) is downregulated in GCs from patients with biochemical POI (bPOI), and we show a significant correlation between downregulated GCAT1 and serum levels of follicle-stimulating hormone and anti-Müllerian hormone. Downregulation of GCAT1 inhibited G1/S cell cycle progression and thus inhibited the proliferation of GCs. Mechanistically, we show that GCAT1 competes with cyclin-dependent kinase inhibitor 1B ( CDKN1B ) mRNA for polypyrimidine tract-binding protein 1 (PTBP1) binding, and thus decreased GCAT1 might promote PTBP1 binding to CDKN1B mRNA and thereby initiate CDKN1B protein (p27) translation. Together, our results suggest that downregulation of GCAT1 under conditions of bPOI inhibits the proliferation of GCs through PTBP1-dependent p27 regulation, thus suggesting a novel form of lncRNA-mediated epigenetic regulation of GC function that contributes to the pathogenesis of POI.

This research was supported by National Basic Research Program of China (973 Program) (2012CB944700), the State Key Program of National Natural Science Foundation of China (81430029), the National Natural Science Foundation of China (81270662, 81471509), China Postdoctoral Science Foundation (2014M561939) and the Scientific Research Foundation of Shandong Province of Outstanding Young Scientists (BS2014YY013, 2014BSE27022). The authors have no competing interests.