Deficiency of OGT-mediated O-GlcNAcylation causes female infertility with oocyte meiotic arrest and follicle development defects by impairing mitochondrial function

Abnormalities in oocyte meiosis are a major cause of female infertility. Since transcriptional activity is largely absent during oocyte meiosis, post-translational modifications of proteins play an essential regulatory role. Among these, OGT-mediated O-GlcNAcylation is a key modification involved in various biological processes. However, its specific function during oocyte maturation remains unclear. In this study, we demonstrate that conditional knockout of OGT in growing mouse oocytes using Gdf9-Cre leads to complete female infertility. OGT depletion prevented germinal vesicle breakdown and polar body extrusion, resulting in meiotic arrest. Although spindle formation and chromosome alignment were unaffected, OGT loss disrupted kinetochore-microtubule attachments and activated the spindle assembly checkpoint. Furthermore, OGT deletion caused excessive follicle depletion and reduced the number of ovulated oocytes. Multi-omics analysis showed that OGT-deficient oocytes exhibited downregulated expression of mitochondrial respiratory chain complex I proteins and impaired NADH-to-NAD+ conversion. Functional assays confirmed that OGT deficiency compromises mitochondrial function, as evidenced by abnormal mitochondrial distribution, decreased membrane potential, reduced ATP levels, and increased oxidative stress. In summary, our data establish OGT-mediated O-GlcNAcylation as a fundamental determinant of oocyte maturation and provide new insights into its role in supporting female fertility.