DWORF Gene Therapy Improves Cardiac Calcium Handling and Mitochondrial Function.

Abstract

BACKGROUND Calcium (Ca2+) dysregulation is a hallmark of heart failure, impairing excitation-contraction coupling and contributing to pathological remodeling. The SERCA2a (sarco/endoplasmic reticulum Ca2+ ATPase isoform 2a) mediates Ca2+ reuptake into the sarcoplasmic reticulum (SR) during diastole, but its activity declines in failing hearts. DWORF (dwarf open reading frame), a newly identified cardiac microprotein, enhances SERCA2a activity and improves cardiomyocyte Ca2+ cycling and contractility. SR Ca2+ release also influences mitochondrial metabolism and ATP production. Here, we investigated whether DWORF overexpression improves SR Ca2+ handling, augments mitochondrial Ca2+ signaling, and protects against heart failure progression. METHODS Transgenic and adeno-associated virus approaches were used to overexpress DWORF in the heart. Mice underwent transverse aortic constriction to model pressure overload-induced heart failure. Cardiac function, mitochondrial metabolism, SR Ca2+ uptake, and remodeling were assessed. RESULTS Mitochondria from DWORF transgenic hearts displayed increased basal respiration, maximal respiration, and spare respiratory capacity, correlating with enhanced mitochondrial Ca2+ uptake kinetics. Western blot analysis showed elevated levels of active PDH (pyruvate dehydrogenase) and mitochondrial Ca2+ uniporter expression in DWORF transgenic hearts, supporting a role for DWORF in Ca2+-driven metabolic regulation. Similarly, MyoAAV-mediated DWORF overexpression enhanced mitochondrial respiration and increased levels of active PDH in adult mice. Following TAC, MyoAAV-DWORF-treated mice maintained higher left ventricular function and were protected from further deterioration compared with controls. This benefit was observed when DWORF gene therapy was delivered preventively at the time of pressure overload or after heart failure was already established. DWORF gene therapy also attenuated remodeling, with lower heart weight and lung weight-to-tibia length ratios. Seahorse analysis confirmed sustained mitochondrial improvements in both treatment paradigms. CONCLUSIONS DWORF overexpression enhances SR Ca2+ dynamics, improves mitochondrial energetics, and attenuates pathological remodeling and heart failure progression in response to pressure overload. These findings support DWORF as a promising therapeutic target for heart failure.