Diabetic cardiomyopathy is a common complication in patients with diabetes and is associatedwith impaired responsiveness of ischemic myocardium to proangiogenic factors, subsequentlyleading to heart failure. STK35, a novel kinase that binds to nuclear actin, has been shown toregulate important cellular functions such as cell migration, proliferation, survival, andangiogenesis. Currently, the contribution of altered STK35 expression in human diseases remainsunexplored. In initial studies, we observed that human cardiac biopsies from diabetic patientsshowed a significant decrease in STK35 expression as compared to non-diabetic control hearts.Intriguingly, in a STZ-induced mouse model of diabetes, i.v . injection of rAAV9-STK35 to expressconstitutive STK35 in heart in FVB/N male mice promoted neovascularization and lowered cardiacfibrosis, leading to improved cardiac function of diabetic heart. Our in vitro studies observed highglucose decreased STK35 expression in mouse cardiac endothelial cells (MCEC), whereasSTK35 overexpression increased MCEC migration and vascular tube formation, and upregulatedMCEC to expression of multiple pro-angiogenic proteins. Taken together, our results demonstratethat cardiac-targeted STK35 gene therapy exerts a marked beneficial action by attenuating bothcardiac remodeling and cardiac function in a mouse model of diabetes mellitus. Mechanistically,the beneficial effect may be attributed, at least partially, to enhanced neovascularization in heart.