Abstract 15660: Impaired Mitochondrial Quality Control Drives the Development of Cardiomyopathy in Anderson-Fabry Disease

Abstract

Introduction: Anderson-Fabry disease (AFD) is a systemic disorder caused by impaired alpha-galactosidase (GLA) activity, leading to a progressive cardiomyopathy, with hypertrophy and diastolic dysfunction. However, the molecular mechanisms underlying these features are unknown. Aim: To explore the role of mitochondria as a pathogenic mechanism of cardiac dysfunction in AFD. Methods: We tested a transgenic mouse that lacks endogenous GLA and expresses human R301Q-GLA [Tg/GLA knockout]. We performed serial ecochardiographic, histological, and biochemical analyses on cardiac tissue and single cell contractility on isolated adult cardiomyocytes (CM). Moreover, we assessed mitochondrial morphology/function in mouse embryonic fibroblasts (MEFs). Results: AFD-MEFs display an impaired mitochondrial respiration and reduced ATP synthesis. Increased mitochondrial levels of DRP1, LC3II, and MFN-ubiquitination along with accumulation of fragmented mitochondria and autophagosomes indicate the presence of mitophagy-targeted mitochondria that were not removed. Reduced PGC-1a and mitochondrial-DNA synthesis in AFD-MEFs indicate impaired mitochondrial biogenesis as well. Altogether, our data indicate impaired mitophagy and quality control of AFD-mitochondria. At echocardiography, AFD mice showed diastolic dysfunction and hypertrophy starting from 9 months. Isolated AFD-CMs exhibit reduced inotropic response to isoproterenol. Remarkably, alterations of cardiac mitochondrial function were observed starting from 3 months, including increased levels of MFN2-ubiquitination, DRP1 and LC3II, decreased levels of PGC-1a along with accumulation of disarranged mitochondria and autophagosomes. Frank impairment of mitochondrial respiration in AFD-CMs and reduced myocardial ATP-content was detected from 6 months, together with increased release of Cytochrome-C in the cytosol. Strikingly, mitochondrial dysfunction was also detected in fibroblasts isolated from AFD patients, which have a significantly reduced electron transport chain activity. Conclusions: In AFD, energetic alterations associated with impaired autophagy/mitophagy, are evident at 3 months and progressively lead to cardiac hypertrophy and dysfunction.