Reduced Endothelin-2 and Hypoxic Signaling Pathways in Granulosa-Lutein Cells of PCOS Women

• Main Authors: Magdalena Szymanska, Ketan Shrestha, Eliezer Girsh, Avi Harlev, Iris Eisenberg, Tal Imbar, Rina Meidan
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: International Journal of Molecular Sciences
• Subjects: miR-210; <i>VEGFA</i>; <i>HIF-1α</i>; ovulation; corpus luteum
• Online Access: https://www.mdpi.com/1422-0067/22/15/8216
• ISSN: 1661-6596; 1422-0067

Granulosa-lutein cells (GLCs) from PCOS women display reduced <i>HIF-1α</i> and <i>EDN2</i> levels, suggesting their role in PCOS etiology. Here, we investigated the mechanisms involved in aberrant <i>EDN2</i> expression in PCOS, and its association with <i>HIF-1α</i>. Various <i>HIF-1α</i>-dependent factors were studied in GLCs from PCOS and compared to normally ovulating women. MicroRNA-210 (miR-210), its target genes (<i>SDHD</i> and <i>GPD1L</i>), and <i>HIF-1α</i>-responsive genes (<i>EDN2</i> and <i>VEGFA</i>) differed in GLCs from PCOS, compared with those of healthy women. Levels of miR-210—designated hypoxiamiR—and <i>EDN2</i> were reduced in the PCOS GLCs; concomitantly, <i>GPD1L</i> and <i>SDHD</i> levels were elevated. Cultured GLCs retained low <i>EDN2</i> expression and had low <i>HIF-1α</i> levels, providing evidence for a disrupted hypoxic response in the PCOS GLCs. However, <i>VEGFA</i> expression was elevated in these cells. Next, miR-210 levels were manipulated. miR-210-mimic stimulated <i>EDN2</i> twice as much as the miR-NC-transfected cells, whereas miR-210-inhibitor diminished <i>EDN2,</i> emphasizing the importance of hypoxiamiR for <i>EDN2</i> induction. Intriguingly, <i>VEGFA</i> transcripts were reduced by both miR-210-mimic and -inhibitor, demonstrating that <i>EDN2</i> and <i>VEGFA</i> are distinctly regulated. Disrupted hypoxic response in the GLCs of periovulatory follicles in PCOS women may play a role in ovulation failure, and in the reduced fertility prevalent in this syndrome.