Abstract Body (Do not enter title and authors here): Background: Heart failure with reduced ejection fraction (HFrEF) affects over 3 million adults in the United States and is associated with high morbidity and mortality, with five-year survival rates below 50%. HFrEF is characterized by impaired myocardial contractility and energy metabolism, with disrupted coupling between sarcomeric force production and energy transduction, known as mechano-energetics. Our previous study demonstrated that adeno-associated virus (AAV)-mediated gene delivery of PERM1, a striated muscle-specific regulator of mitochondrial bioenergetics, enhances cardiac contractility in mice, underscoring its therapeutic potential in HFrEF. However, the mechanisms by which PERM1 modulates myocardial contractility remain largely unknown.

Hypothesis: We hypothesized that PERM1 enhances cardiac contractility via a non-canonical mechanism by acting as a signaling nexus that links metabolic regulation to sarcomeric function.

Methods and Results: Bioinformatic analysis of mass spectrometry-based screening identified myosin-binding protein C3 (MYBPC3), a cardiac-specific regulator that limits actin-myosin cross-bridge formation, as a PERM1-interacting protein. Co-immunoprecipitation confirmed interactions of PERM1 with both MYBPC3 and creatine kinase B (CKB), a stress-responsive isoform essential for ATP delivery to the sarcomere. Super-resolution stochastic optical reconstruction microscopy (STORM) revealed complexing of CKB with troponin C in cardiomyocytes from AAV-PERM1-treated hearts, which was markedly reduced in PERM1-null hearts (Figure 1). Furthermore, MYBPC3 expression was significantly decreased in AAV–PERM1–treated hearts (74.2% reduction vs. AAV-GFP controls, p<0.01).

Conclusions: These findings suggest that PERM1 enhances cardiac contractility by downregulating MYBPC3 to promote actin-myosin interactions and by anchoring CKB to the sarcomere to couple energy metabolism with contractile function. Collectively, our data uncover a novel role for PERM1 in regulating myocardial contractility through direct sarcomeric metabolic integration.