Inhibition of HDAC6 promotes in vitro maturation of Tan sheep oocytes by bidirectionally and synergistically regulating EGFR/CNP expression via histone acetylation.

This study aims to elucidate the regulatory role and molecular mechanism of histone deacetylase 6 (HDAC6) in the in vitro maturation (IVM) of Tan sheep oocytes. Using a granulosa cell-oocyte co-culture model supplemented with the HDAC6-specific inhibitor Tubastatin A (Tub A), combined with cell biology and molecular biology techniques, we analyzed its effects on oocyte maturation rate, mitochondrial function, reactive oxygen species (ROS) levels, and related signaling pathways. The results showed that inhibition of HDAC6 significantly improved the oocyte maturation rate, ameliorated mitochondrial distribution, reduced ROS levels, and enhanced the blastocyst formation rate post in vitro fertilization (IVF). The underlying mechanism may involve histone acetylation modifications at sites H4K5, H4K12, H3K14, H4K16, and H3K27. This leads to the upregulation of epidermal growth factor receptor (EGFR) expression and downregulation of C-type natriuretic peptide (CNP) expression, subsequently regulating the expression of downstream genes (TTP, CX37, CX43, PDE3A), ultimately promoting the IVM of Tan sheep oocytes. This study reveals that HDAC6 likely influences oocyte maturation via a molecular network involving bidirectional and synergistic regulation of EGFR/CNP through histone epigenetic modifications, providing a theoretical basis for optimizing the IVM culture system for Tan sheep oocytes.