PHB2 protects against pressure overload-induced myocardial remodeling in mice via stabilizing TOMM40 and regulating mitochondrial morphofunctional homeostasis

Myocardial remodeling is critical pathological processes in various cardiovascular diseases, where redox imbalance and mitochondrial bioenergetic perturbations emerge as key determinants. Prohibitin 2 (PHB2), which resides in the mitochondrial inner membrane, serves as a critical regulator of mitochondrial homeostasis. In this study we investigated the protective role of PHB2 in transverse aortic constriction (TAC)-induced cardiac remodeling with a particular focus on its ability to safeguard the heart by improving mitochondrial function and alleviating oxidative stress. We revealed that PHB2 expression was significantly decreased in the heart of TAC mice and in Ang II (1 μM)-treated cardiomyocytes. Cardiac-specific PHB2 overexpression mitigated TAC-induced cardiac remodeling, improving cardiac function and attenuating hypertrophy. Additionally, PHB2 overexpression effectively suppressed oxidative stress in the hearts of TAC mice, while improving mitochondrial morphology and the integrity of inner membrane structure. Furthermore, PHB2 overexpression restored mitochondrial function in Ang II-treated cardiomyocytes evidenced by elevated ATP levels and enhanced oxidative phosphorylation capacity. IP-MS analysis revealed that PHB2 directly interacted with Transporter of Outer Mitochondrial Membrane 40 (TOMM40) to regulate mitochondrial function. Importantly, silencing TOMM40 abolished the protective effects of PHB2. We demonstrated that PHB2 preserves TOMM40 protein levels predominantly through inhibition of ubiquitin-dependent proteasomal degradation. Collectively, we discover a new function of PHB2 in safeguarding mitochondrial morphofunctional homeostasis in response to pathological stress through facilitating TOMM40 stabilization, suggesting PHB2 as a promising therapeutic target for potential interventions in heart diseases.