Junctophilin-2 expression silencing causes cardiocyte hypertrophy and abnormal intracellular calcium-handling.

Abstract

Junctophilin-2 (JPH2), a protein expressed in the junctional membrane complex, is necessary for proper intracellular calcium (Ca(2+)) signaling in cardiac myocytes. Downregulation of JPH2 expression in a model of cardiac hypertrophy was recently associated with defective coupling between plasmalemmal L-type Ca(2+) channels and sarcoplasmic reticular ryanodine receptors. However, it remains unclear whether JPH2 expression is altered in patients with hypertrophic cardiomyopathy (HCM). In addition, the effects of downregulation of JPH2 expression on intracellular Ca(2+) handling are presently poorly understood. We sought to determine whether loss of JPH2 expression is noted among patients with HCM and whether expression silencing might perturb Ca(2+) handling in a prohypertrophic manner.