CPNE5 overexpression inhibits cardiomyocytes apoptosis by promoting the degradation of FAS receptor.

CPNE5, a member of the Copine family, is characterized by its membrane-binding properties and functions as a regulatory modulator of intracellular signaling through the spatial redistribution of interacting protein partners. Emerging evidence has demonstrated that CPNE3 exerts cardioprotective effects via anti-apoptotic activity in myocardial ischemia-reperfusion injury models. However, the functional role of CPNE5 in cardiac pathology remains unclear. In this study, the cardiac-specific overexpression of CPNE5 in mice improved cardiac function, reduced cellular apoptosis, and attenuated cardiac fibrosis in both transverse aortic constriction and ischemia-reperfusion models. Conversely, CPNE5 knockout mice exhibited opposite pathological phenotypes. Mechanistic studies revealed that CPNE5 retains FAS within the endoplasmic reticulum and promotes its degradation through the ER-phagy pathway. This process involves CPNE5's interaction with the autophagy marker LC3 and CALCOCO1, a key receptor in the ER-lysosome-associated degradation (ERLAD) pathway. Collectively, these findings indicate that CPNE5 overexpression protects cardiomyocytes against FASL-induced apoptosis under stress and ischemic conditions.