Knockdown of SOX4 attenuates sepsis myocardial injury by inhibiting the EZH2/H3K27me3/SOCS3 axis

Abstract

Inhibition of SOX4 has been reported to ameliorate myocardial ischemic injury, yet its role in sepsis myocardial injury remains unknown. To explore the protective effects and mechanisms of SOX4 inhibition in septic myocardial injury. AC16 cardiomyocytes were exposed to LPS to mimic sepsis-induced myocardial injury. Cell viability was measured by CCK-8 assay, apoptosis by flow cytometry and TUNEL staining, and apoptosis-related proteins by western blot. The connection between SOX4 and EZH2 was validated using co-immunoprecipitation (co-IP) assay and immunofluorescence. Additionally, chromatin immunoprecipitation (ChIP) was employed to detect the enrichment of H3K27me3 in SOCS3 promoter region. The results showed that SOX4 and EZH2 were significantly elevated in septic patients, and their expression levels were positively correlated. In LPS-treated AC16 cardiomyocytes, the expressions of SOX4 and EZH2 increased, while the expression of SOCS3 decreased. Knockdown of SOX4 enhanced AC16 cell viability and inhibited LPS-induced apoptosis. SOX4 and EZH2 colocalized within AC16 cells, and co-IP assays confirmed their interaction. Elevated EZH2 expression reduced the protective impact of SOX4 knockdown in AC16 cells. Silencing EZH2 reduced the enrichment of H3K27me3 in SOCS3 promoter region and thereby promoting SOCS3 expression. Overexpression of SOCS3 promoted AC16 cell survival and partially reversed the damaging effect of EZH2 overexpression on cell survival. Animal experiments confirmed that knockdown of SOX4 attenuated myocardial injury in CLP sepsis mouse model. Knockdown of SOX4 reduces the H3K27me3 methylation level of the SOCS3 promoter by inhibiting EZH2 expression, thereby promoting SOCS3 expression and attenuating myocardial injury.