Targeting PKGIα Cys⁴² attenuates cardiac dysfunction in heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a highly prevalent condition associated with substantial morbidity and mortality, yet effective therapeutic options remain limited. As oxidation of Cys⁴² in cyclic guanosine monophosphate (cGMP)-dependent protein kinase Iα (PKGIα) can enhance vessel and diastolic relaxation, processes impaired in HFpEF, we sought to target this mechanism using natural compounds with predicted thiol reactivity. Among these, urolithin A emerged as a compound with a previously unidentified and counterintuitive mode of action, directly modifying Cys⁴² in PKGIα. In a multihit HFpEF model that closely mimics the human condition, urolithin A improved diastolic function and attenuated cardiac remodeling through cysteine 42-dependent activation of PKGIα. These findings were further validated in human engineered heart tissue, where urolithin A enhanced both relaxation and contraction kinetics. These findings collectively highlight Cys⁴² in PKGIα as a promising therapeutic target for HFpEF and identify urolithin A as a previously unidentified activator of this protective mechanism.