TRIC-A Facilitates Sarcoplasmic Reticulum–Mitochondrial Ca2+ Signaling Crosstalk in Cardiomyocytes

TRIC-A is an intracellular cation channel enriched in excitable tissues that is recently identified as a key modulator of sarcoplasmic reticulum (SR) Ca²⁺ homeostasis through direct interaction with type 2 ryanodine receptors (RyR₂). Given the intimate anatomical and functional coupling between the SR and mitochondria, we investigated whether TRIC-A contributes to SR-mitochondrial crosstalk under cardiac stress conditions. Using a transverse aortic constriction (TAC) model, we found that TRIC-A^-/- mice developed more severe cardiac hypertrophy, underwent maladaptive remodeling, and activated apoptotic pathways compared with wild-type littermates. At the cellular level, TRIC-A-deficient cardiomyocytes were more susceptible to H₂O₂-induced mitochondrial injury and displayed abnormal mitochondrial morphology. Live-cell imaging revealed exaggerated mitochondrial Ca²⁺ uptake during caffeine stimulation and increased propensity for store-overload-induced Ca²⁺ release (SOICR). Complementary studies in HEK293 cells expressing RyR₂ demonstrated that exogenous TRIC-A expression attenuates RyR₂-mediated mitochondrial Ca²⁺ overload, preserves respiratory function, and suppresses superoxide generation. Together, these findings identify TRIC-A as a critical regulator of SR-mitochondrial Ca²⁺ signaling. By constraining mitochondrial Ca²⁺ influx and limiting oxidative stress, TRIC-A safeguards cardiomyocytes against SOICR-driven injury and confers protection against pressure overload-induced cardiac dysfunction.