Abstract：SETD2 is H3K36Me3-specific methyltransferase, which participates in histone methylation modification and affects cell function by regulating the expression of multiple genes. The purpose of this experiment is to explore the expression rule and function of SETD2 in vitro maturation of porcine oocyte (IVM).The expression and localization of SETD2 and H3K36me3 in porcine oocyte IVM at different stages (GV,MⅠ, MⅡ) were detected by immunofluorescence staining.The interference model was constructed by microinjection of SETD2 interfering RNA(SETD2-siRNA) at GV stage, and the effects of interference on SETD2, H3K36me3, DNA double strand break marker(γH2AX) and the first polar body (PBI) excretion rate were detected. qPCR was used to detect the effects of interference on DNA methyltransferase DNMT3B, apoptosis and anti-apoptosis related genes BAX and BCL2 expression. The results showed that the GV phase of SETD2 was clustered around DNA, M Ⅰ and M Ⅱ were expressed in cytoplasm, and H3K36me3 was colocalized with nucleithroughout meiosis. Further study showed that SETD2 and H3K36me3 expression levels were significantly decreased after SETD2-siRNA interference, while γH2AX expression was increased (P<0.05), and PBI excretion rate was significantly decreased (P<0.05). qPCR results showed that the expression of DNMT3B was not significantly different after SETD2-siRNA interference, but the expression level of BCL2 was significantly decreased, and the apoptosis-related gene BAX was significantly
increased (P<0.05). In conclusion, SETD2 plays an important role in in vitro maturation of oocytes.Interference by SETD2-siRNA reduces the methylation level of H3K36me3, leads to increased DNA breakage, induces cell apoptosis, and affects the maturation efficiency and quality of porcine oocytes
IVM.
