# MiR-31 enhances porcine oocyte maturation via MAPK8/JNK-mediated cumulus expansion and cytoplasmic maturation

## TL;DR

This study shows that miR-31 improves the maturation of pig oocytes by regulating the MAPK8/JNK pathway, enhancing cumulus cell expansion and oocyte quality.

## Contribution

The study identifies miR-31 as a novel regulator of porcine oocyte maturation through the MAPK8/JNK pathway.

## Key findings

- miR-31 overexpression increases cumulus cell expansion and oocyte maturation rates.
- miR-31 improves oocyte quality by enhancing mitochondrial function and redox balance.
- Inhibiting miR-31 activates the MAPK8/JNK pathway and disrupts oocyte maturation.

## Abstract

This study elucidates the molecular mechanism by which porcine ovarian cumulus cell-derived miR-31 regulates oocyte IVM through the MAPK8/JNK signaling pathway, with particular emphasis on its biological roles in cumulus cell expansion and oocyte maturation quality. The experimental design comprised four treatment groups: miR-31 mimics group, mimics negative control (NC) group, miR-31 inhibition group, and inhibition NC group. The results showed: 1) miR-31 overexpression significantly enhanced cumulus cell expansion processes, upregulating PTGS2 (P < 0.05) and PTX3 (P < 0.01) gene expression, while concurrently increasing oocyte maturation rates (P < 0.05). 2) Oocyte quality analysis revealed that miR-31 overexpression induced: elevated mitochondrial membrane potential (P < 0.05); increased ATP production (P < 0.05); reduced lipid droplet size (P < 0.05) with concurrent quantity increased (P < 0.05); improved redox homeostasis (P < 0.05). Conversely, miR-31 inhibition demonstrated opposing effects: elevated cortical granule misdistribution rate (P < 0.05); Significant activation of MAPK8/JNK pathway activity (P < 0.01). In conclusion, this study demonstrates that miR-31 coordinates cumulus cell expansion with oocyte metabolic reprogramming by targeting MAPK8, thereby enhancing nuclear-cytoplasmic maturation synchrony.

This study demonstrates that cumulus cell-derived miR-31 promotes the in vitro maturation of porcine oocytes through targeting MAPK8. These results identify miR-31 as a novel regulatory target for enhancing oocyte quality in porcine reproductive technologies.