Optogenetic mitochondrial preconditioning enhances cardiomyocyte survival under stress

Mitochondria play a central role in preconditioning-mediated cytoprotection, yet the specific role of mitochondrial membrane potential (ΔΨ_m) in this process remains incompletely understood. In this study, we employed a next-generation, mitochondrial-targeted optogenetic system (mOpto) to induce precisely controlled (partial and transient) ΔΨ_m depolarization and investigate its role in enhancing cardiomyocyte resilience to stress. Human AC16 cardiomyocytes expressing mOpto were subjected to low-intensity LED illumination for preconditioning, followed by exposure to stressors including FCCP, H₂O₂, or simulated ischemia-reperfusion. mOpto-preconditioned cells exhibited significantly improved viability, attenuated ΔΨ_m depolarization, and reduced reactive oxygen species (ROS) production compared to non-preconditioned controls. Notably, this cytoprotective effect occurred independently of canonical ROS signaling and mitochondrial ATP-sensitive potassium channel (mitoK_ATP) activation. Transcriptional analysis revealed coordinated mitochondrial and metabolic reprogramming, including upregulation of genes involved in lipid biosynthesis, mitochondrial quality control, energy homeostasis, and a shift toward mitochondrial fusion. Importantly, mOpto preconditioning conferred similar cytoprotective effects in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), underscoring the translational potential of this approach. These findings demonstrate that mOpto-mediated transient ΔΨ_m depolarization induces a preconditioning effect that enhances cardiomyocyte resilience through the establishment of a mitochondrial "memory" and dynamic remodeling of mitochondrial function.