Role of Dyadic Proteins in Proper Heart Function and Disease

Cardiovascular disease encompasses a wide group of conditions that affect the heart and blood vessels. Of these diseases, cardiomyopathies and arrhythmias specifically have been well studied in their relationship to cardiac dyads, nanoscopic structures that connect electrical signals to muscle contraction. The proper development and positioning of dyads is essential in excitation-contraction (EC) coupling and thus beating of the heart. Three proteins: CMYA5, JPH2 and BIN1 are responsible for maintaining the dyadic cleft between the T-tubule and junctional sarcoplasmic reticulum (jSR). Various other dyadic proteins play integral roles in the primary function of the dyad – translating a propagating action potential (AP) into myocardial contraction. Ca2+, a secondary messenger in this process, acts as an allosteric activator of the sarcomere and its cytoplasmic concentration is regulated by the dyad. Loss of function mutations have been shown to result in cardiomyopathies and arrhythmias. Adeno-associated virus (AAV) gene therapy with dyad components can rescue dyadic dysfunction that results in cardiomyopathies and arrhythmias. Overall, the dyad and its components serve as essential mediators of calcium homeostasis and excitation contraction-coupling in the mammalian heart and when dysfunctional, result in significant cardiac dysfunction, arrhythmias, morbidity and mortality.