3C suppresses PINK1-mediated mitophagy and contributes to coxsackievirus B3 replication.

Viral myocarditis (VM) is a cardiac inflammatory condition caused by viral infection and serves as a critical precursor to life-threatening complications, such as dilated cardiomyopathy and heart failure. Coxsackievirus B3 (CVB3), a predominant etiological agent of VM, lacks targeted therapeutic interventions despite ongoing antiviral development. Mitophagy is a selective mitochondrial quality control mechanism mediated by PINK1. It has two key roles: maintaining mitochondrial homeostasis and regulating innate antiviral immunity. Here, we employed single-cell RNA sequencing to reveal a significant correlation between impaired mitophagy and cardiomyocyte pathology in CVB3-induced myocarditis. We demonstrated that CVB3 infection suppresses PINK1-dependent mitophagy, while the attenuation of PINK1 reciprocally enhances CVB3 replication. Mechanistically, CVB3 non-structural protein 3C promotes the degradation of mitochondrial antiviral signaling protein (MAVS). MAVS interacts with PINK1 to form a regulatory loop: PINK1 deficiency boosts MAVS reduction, which further promotes viral replication and worsens myocardial injury. Furthermore, we identify the transcription factor FOSL1 as a novel negative regulator of PINK1 transcription through direct promoter binding. Collectively, these findings show that the 3C/FOSL1/PINK1/MAVS signaling axis is a key mechanism in CVB3 pathogenesis. We propose innovative therapeutic targets for viral myocarditis through restoration of mitochondrial homeostasis and modulation of host-virus interactions.