Decreased microRNA-125b-5p disrupts follicle steroidogenesis through targeting PAK3/ERK1/2 signalling in mouse preantral follicles

Metabolism. 2020 Jun:107:154241. doi: 10.1016/j.metabol.2020.154241. Epub 2020 Apr 15.

Abstract

Background: Hyperandrogenism is one of the major characteristics of polycystic ovary syndrome (PCOS). Abnormal miR-125b-5p expression has been documented in multiple diseases, but whether miR-125b-5p is associated with aberrant steroidogenesis in preantral follicles remains unknown.

Methods: Steriod hormone concentrations and miR-125b-5p expression were measured in clinical serum samples from PCOS patients. Using a mouse preantral follicle culture model and a letrozole-induced PCOS mouse model, we investigated the mechanism underlying miR-125b-5p regulation of androgen and oestrogen secretion.

Results: The decreased miR-125b-5p expression was observed in the sera from hyperandrogenic PCOS (HA-PCOS) patients. In mouse preantral follicles, inhibiting miR-125b-5p increased the expression of androgen synthesis-related genes and stimulated the secretion of testosterone, while simultaneously downregulating oestrogen synthesis-related genes and decreasing oestradiol release. Ectopically expressed miR-125b-5p reversed the effects on steroidogenesis-related gene expression and hormone release. Mechanistic studies identified Pak3 as a direct target of miR-125b-5p. Furthermore, inhibiting miR-125b-5p facilitated the activation of ERK1/2 in mouse preantral follicles, while inhibiting Pak3 abrogated this activating effect. These results were recapitulated in letrozole-induced PCOS mouse ovaries. Of note, inhibiting PAK3 antagonised the positive effect of miR-125b-5p siRNA on the expressions of androgen synthesis-related enzymes and testosterone secretion. Luteinizing hormone (LH) inhibited miR-125b-5p expression, and stimulated Pak3 expression.

Conclusion: High serum LH concentrations in PCOS patients repress miR-125b-5p expression, which further increases Pak3 expression, leading to activation of ERK1/2 signalling, thus stimulating the expression of androgen synthesis-related enzymes and testosterone secretion in HA-PCOS.

Keywords: Pak3; Polycystic ovary syndrome; Steroidogenesis; miR-125b-5p.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androgens / biosynthesis
  • Androgens / genetics
  • Animals
  • Estradiol / metabolism
  • Estrogens / biosynthesis
  • Estrogens / genetics
  • Female
  • Gene Expression Regulation / genetics
  • Hyperandrogenism / chemically induced
  • Hyperandrogenism / metabolism
  • Letrozole
  • Luteinizing Hormone / metabolism
  • MAP Kinase Signaling System / drug effects
  • MAP Kinase Signaling System / genetics
  • Mice
  • Mice, Inbred C57BL
  • MicroRNAs / genetics*
  • Ovarian Follicle / metabolism*
  • Polycystic Ovary Syndrome / chemically induced
  • Polycystic Ovary Syndrome / genetics
  • Polycystic Ovary Syndrome / metabolism
  • Steroids / biosynthesis*
  • p21-Activated Kinases / genetics
  • p21-Activated Kinases / metabolism

Substances

  • Androgens
  • Estrogens
  • MicroRNAs
  • Mirn125 microRNA, mouse
  • Steroids
  • Estradiol
  • Letrozole
  • Luteinizing Hormone
  • Pak3 protein, mouse
  • p21-Activated Kinases