Norepinephrine induces an epigenetic modification of PKCε gene repression in H9c2 cells via increased oxidative stress

Increased sympathetic tone with elevated norepinephrine (NE) is associated with various heart diseases. NE has been shown to downregulate PKCε that protects the heart in ischemia/reperfusion injury. Yet, the molecular mechanisms are unknown. Present study determined the epigenetic mechanisms of NE in regulating PKCε expression in the H9c2 cell line. The protein and mRNA levels were determined by Western blot and real‐time RT‐PCR. Methylation of the PKCε gene promoter and binding of transcription factors were detected by methylation specific PCR and ChIP. Treatment of H9c2 cells with NE for 48 h caused a significant decrease in PKCε mRNA and protein abundance in an α1 adrenoceptor‐dependent manner. Methylation of the SP1 and Egr‐1 binding sites at the PKCε promoter was significantly increased and the binding of SP1 and Egr‐1 was decreased by NE. Inhibition of methylation by 5‐aza‐2’‐deoxycytidine and procainamide rescued the NE‐induced promoter methylation and PKCε gene repression. Additionally, oxidative stress inhibitors NAC and apocynin abolished NE's effect on the promoter methylation, SP1/Egr‐1 binding, and PKCε gene expression, indicating a ROS dependence of NE‐mediated epigenetic modification of PKCε gene repression. The findings demonstrate that NE causes an epigenetic modification of the PKCε promoter and gene repression in H9c2 cells via DNA methylation in an oxidative stress‐dependent manner.