Overexpression of the histidine triad nucleotide-binding protein 2 protects cardiac function in the adult mice after acute myocardial infarction

Aim To explore the role of the histidine triad nucleotide-binding 2 (HINT2) protein in heart failure. Methods Neonatal mouse ventricle myocytes (NMVMs) and myocardial infarction-induced heart failure mice were used for in vitro or in vivo experiments. Adenovirus (ADV) and adeno-associated virus serum type 9 (AAV9) vectors were used to regulate HINT2 expression. The expression of HINT2 was determined by quantifying the mRNA and protein levels. Cell survival was analysed using the CCK-8 kit and TUNEL staining. Mitochondrial function was determined by the mitochondrial membrane potential and oxygen consumption rates. AAV9-HINT2 was injected 24 h post-myocardial infarction following which transthoracic echocardiography and histological analyses were performed after 4 weeks. Positron emission tomography tomography-computed tomography (PET/CT) and targeted metabolomics analyses were used to explore the metabolic status in vivo. NAD levels were measured using a colorimetric kit. Computer-simulated rigid body molecular docking was performed using AUTODOCK4. Molecule binding kinetics assays were performed using biolayer interferometry. Results HINT2 was down-regulated in NMVMs in hypoxia. ADV-HINT2-induced HINT2 overexpression improved NMVM survival after exposure to hypoxia. Mitochondrial function was preserved in the ADV-HINT2 group under hypoxic conditions. In vivo experiments showed that cardiac function and metabolic status was preserved by HINT2 overexpression. HINT2 overexpression restored mitochondrial NAD levels; this was dependent on nicotinamide mononucleotide (NMN). Using computer-simulated molecular docking analysis and biolayer interferometry, we observed that HINT2 potentially binds and associates with NMN. Conclusion HINT2 overexpression protects cardiac function in adult mice after myocardial infarction by maintaining mitochondrial NAD homeostasis.