Abstract 4139743: Alfa-tubulin detyrosination causes mitochondrial dysfunction through suppression of Parkin-mediated mitophagy linking to heart failure with preserved ejection fraction

Background: Alfa-tubulin detyrosination is one of the post-translational modifications of tubulin c-terminal tail, observed in failing cardiomyocytes. Tubulin is known to regulate mitochondrial function, however, the effects of detyrosinated α-tubulin on mitochondrial function remains unrevealed. Methods and Results: We tested the effects of α-tubulin detyrosination on mitochondrial function with tubulin tyrosine ligase knocked out (TTL KO) H9C2 and Vasohibin 1 overexpressed (VASH1 OE) H9C2 cells, which had high amounts of detyrosinated α-tubulin. Alfa-tubulin detyrosination reduced mitochondrial respiration and mitochondrial membrane potential. Moreover, we found mitophagy, evaluated with Mito-Keima fluorescence and LC3 lipidation, were suppressed in TTL KO and VASH1 OE cells. Mitochondria in detyrosinated α-tubulin increasing cells contained less ubiquitinated proteins, suggesting that α-tubulin detyrosination might inhibit Parkin-mediated mitophagy. Next, we overexpressed VASH1 in the mouse heart with AAV9 to validate the effects of detyrosinated α-tubulin on cardiac function. Cardiomyocyte-restricted overexpression of VASH1 led to heart failure with preserved ejection fraction (HFpEF) evidenced by prolonged isovolumic relaxation time and increased mitral E/E' ratio. Cardiac VASH1 OE mice also displayed a reduction in running distance during exercise exhaustion test. The VASH1 OE heart showed suppressed LC3 lipidation, suggesting decreased mitophagy. Conclusion: We demonstrated α-tubulin detyrosination reduces mitochondrial function through the inhibition of mitophagy, leading to HFpEF progression. Our study elucidates that α-tubulin detyrosination may act as a potential target for the novel therapy for HFpEF patients.