Tet methylcytosine dioxygenase 2(TET2)-dependent epigenetic regulation in the pathogenesis of polycystic ovary syndrome.

UNLABELLED: Polycystic Ovary Syndrome (PCOS) is a complex endocrine disorder and a major cause of female infertility. While epigenetic dysregulation, notably DNA methylation, has been recognized as a key driver of PCOS pathogenesis, the specific involvement of active demethylation mediated by Ten-Eleven Translocation (TET) enzymes in the onset of the disease is currently poorly understood. In order to explore the role of TET2-mediated 5-hydroxymethylcytosine (5hmC) modifications and the underlying molecular drivers of PCOS, genome-wide 5hmC profiling was utilized to analyze granulosa cells from both PCOS patients and normal controls. Higher global 5hmC levels and TET2 expression were found in the granulosa cells of PCOS patients. Through integrated analysis, significant alterations in 5hmC at specific genomic loci were revealed, which were enriched in pathways related to MAPK signaling, gap junction communication, and oocyte meiosis. Furthermore, USP45 was identified as a downstream target of TET2 via ChIP-seq analysis. Functional experiments demonstrated that TET2 drives the overactivation of autophagic flux under hyperandrogenic conditions by stabilizing PRKAA1 via USP45-mediated deubiquitination. Conversely, pharmacological inhibition of TET2 effectively rescued these autophagic abnormalities. TET2-mediated 5hmC modification is revealed by this study as a key driver of PCOS pathogenesis; these insights offer a novel epigenetic framework for the development of PCOS therapies. GRAPHICAL ABSTRACT: The underlying mechanisms of TET2-mediated 5hmC epigenetic regulation in PCOS progression. Genome-wide 5hmC profiling in PCOS patient granulosa cells revealed increased global 5hmC levels and elevated TET2 expression. Integrated analysis showed significant 5hmC alterations at specific genomic loci, enriching pathways like MAPK signaling and oocyte meiosis. Crucially, we identified USP45 as a novel TET2 target, demonstrating that TET2 promotes hyperandrogenism-induced autophagy in granulosa cells via USP45-mediated PRKAA1 deubiquitination. These findings provide the first evidence for a significant role of TET2-mediated 5hmC epigenetic regulation in PCOS, linking aberrant epigenetics to impaired ovarian function through excessive autophagy. [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00018-026-06134-z.