EGR1 Mediates Ursodeoxycholic Acid-Promoted Mitophagy to Prevent Postovulatory Aging of Porcine Oocytes

Postovulatory oocyte aging (POA) is a key factor contributing to the decline in female fertility and the success rate of assisted reproductive technology. Currently, most studies on POA have focused on downstream phenotypes such as mitochondrial dysfunction and oxidative stress, while little is known about its key upstream regulatory factors. Here, we show that the downregulation of transcription factor Early Growth Response 1 (EGR1) is a key upstream event driving porcine oocyte aging. Microtranscriptome sequencing combined with experimental validation verified a notable reduction in EGR1 protein abundance in aged oocytes. We found that Ursodeoxycholic Acid (UDCA) upregulated EGR1, which in turn promoted the expression of the autophagy-related protein LC3B and the lysosomal protein LAMP1, while reducing P62 accumulation. Furthermore, UDCA enhanced the expression of mitophagy core proteins PINK1, VDAC1 and promoted mitochondrial-lysosomal colocalization, thereby improving mitophagy and restoring the quality of aged oocytes. Crucially, treatment with the EGR1 inhibitor plicamycin completely blocked UDCA's ability to enhance the developmental potential of aged oocytes, confirming that EGR1-mediated mitophagy was the core pathway underlying UDCA's effects. Collectively, this study innovatively identified EGR1 as a key bridge linking oocyte aging and decreased mitophagy, and clarified the novel mechanism by which UDCA exerts its protective effects through the "UDCA-EGR1-mitophagy" axis. Our findings advanced the research on oocyte aging from phenotypic observation to the upstream transcriptional regulation level, providing a novel theoretical target and experimental basis for fundamentally intervening in reproductive aging.