hERG1 channels and potential therapeutics for long QT syndrome

The human ether-à-go-go-related gene type 1 (hERG1) channel is a voltage-gated potassium channel encoded by the KCNH2 gene. hERG1 channels are essential to the repolarization of cardiac action potentials, and reduced function of the potassium current conducted by hERG1 channels (I_Kr) is pathogenic, leading to type 2 long QT syndrome (LQT2). LQT2 results from congenital mutation(s) of KCNH2 and affects approximately 1 in 6000 people. A mutation-induced decrease in I_Kr can be caused by altered channel gating but is most often caused by misfolding and early degradation of hERG1 protein, resulting in reduced trafficking of channels to the plasma membrane. Prolongation of the QT interval can also be drug induced, and many drugs fail preclinical safety assessments due to their inhibition of hERG1 channels. In this review we assess the molecular and structural bases of hERG1 channel function. Furthermore we examine the pharmacology of hERG1 inhibitors and hERG1 channel trafficking mediators, the pathogenesis of LQT2 that can be triggered through these mechanisms and translational and clinical perspectives that may be useful in the prevention and treatment of LQT2. By understanding the molecular mechanisms that lead to the pathophysiological development of LQT2 new therapeutics can be developed to treat this disorder.