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Comment |
Disrupted Redox Homeostasis and Aberrant Redox Gene Expression in Porcine Oocytes Contribute to Decreased Developmental Competence. Yuan Y et al. The objective of this study was to identify specific redox related genes whose function contributes to oocyte quality, and characterize the role of redox homeostasis in oocyte development. We determined the redox genes glutaredoxin 2 (GLRX2), protein disulfide isomerase family A, member 4 and 6 (PDIA4, PDIA6) and thioredoxin reductase 1 (TXNRD1) were differentially expressed between adult (more competent) and prepubertal (less competent) porcine in vitro matured (IVM) oocytes. The association between these genes and oocyte quality was further validated by comparing transcript abundance in IVM and in vivo matured (VVM) prepubertal and adult oocytes. By maturing oocytes in variable redox environments, we demonstrate that a balanced redox environment is important for oocyte quality, and over-reduction of the environment is as detrimental as excess oxidation. Critical levels of reactive oxygen species (ROS) and glutathione (GSH) are required for oocyte competence. Elevated GSH and lower ROS in prepubertal oocytes suggest disrupted redox homeostasis exists in these cells. By further comparing GLRX2, PDIA4, PDIA6 and TXNRD1 expression in oocytes matured under these different redox environments, we found aberrant expression patterns in prepubertal oocytes, but not in adult oocytes, when the maturation medium contained high concentrations of antioxidants. These results suggest that prepubertal oocytes are less competent in regulating redox balance compared to adult oocytes, contributing to lower oocyte quality. In conclusion, aberrant redox gene expression patterns and disrupted redox homeostasis contribute to decreased developmental competence in prepubertal and in vitro matured porcine oocytes. The balance between ROS and GSH plays an important role in oocyte quality.
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