Construction and analysis of a lncRNA (PWRN2)-mediated ceRNA network reveal its potential roles in oocyte nuclear maturation of patients with PCOS

Background: Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder in women. An lncRNA, namely, Prader-Willi region nonprotein coding RNA 2 (PWRN2), was up-regulated in the cumulus cells of patients with PCOS. However, the molecular mechanism of PWRN2 in PCOS remains largely unknown.

Methods: In this study, the expression levels of PWRN2 were tested in cumulus cells through qRT-PCR analysis to confirm its potential roles in oocyte nuclear maturation of PCOS. A PWRN2-mediated ceRNA network was constructed based on three microarray datasets to investigate the molecular mechanism of PWRN2 in oocyte development of patients with PCOS. The direct interactions of the candidate genes of the ceRNA network were also demonstrated by dual-luciferase reporter assay.

Results: PWRN2 was found to be associated with oocyte nuclear maturation in patients with PCOS in contrast to that in normal patients. Based on the microarray data, 176 lncRNAs (118 up-regulated and 58 down-regulated) and 131 mRNAs (84 up-regulated and 47 down-regulated) were identified to be regulated by PWRN2. A PWRN2-miR-92b-3p-TMEM120B ceRNA network was constructed based on results of analysis of the combined three microarray datasets (lncRNA+mRNA microarray in KGN/shPWRN2 in this study, miRNAs microarray and lncRNA+mRNA microarray in PCOS cumulus cells reported in previous studies). The coexpression characteristics of the genes (PWRN2, miR-92b-3p and TMEM120B) were detected in the cumulus cells of cumulus-oocyte complexes at different nuclear maturity stages in PCOS. These results are in accordance with the ceRNA hypothesis. Moreover, luciferase activity assay revealed that miR-92b-3p directly binds to PWRN2 and targets TMEM120B.

Conclusions: PWNR2 plays important roles in oocyte nuclear maturation in PCOS by functioning as a ceRNA to reduce the availability of miR-92b-3p for TMEM120B target binding during oocyte maturation in PCOS. Our findings would provide new information and clarify abnormal oocyte development in PCOS.