In this study, we demonstrated that Ppp2r5d expression alteration in the DCM model resulted in a cascade of biological responses, including phosphorylation changes of mtSTAT3, decreased activity of the ETC complex, reduced ATP production, increased intracellular ROS levels, and exacerbated myocardial apoptosis. The gene discussed is PPP2R5D; the disease is familial dilated cardiomyopathy.