Vacuolar H⁺-ATPase Preserves Cardiolipin Homeostasis Through the Lysosomal-Mitochondrial Axis to Restrain Cardiac...

Cardiac aging involves progressive mitochondrial dysfunction, contributing to heart failure. Cardiolipin (CL), essential for mitochondrial function, is increasingly depleted in aging cardiomyocytes, promoting mitochondrial decline. Lysosomal degradation relies on v-ATPase (vacuolar-type H+-ATPase)-mediated acidification, and although lysosomes regulate phospholipid metabolism, their roles in CL homeostasis during aging remains unclear. This study examines whether v-ATPase dysfunction drives age-related cardiac changes by disrupting CL metabolism and mitochondrial function.

To investigate underlying mechanisms and causality, we use RNA sequencing, targeted lipidomics, immunofluorescence microscopy, co-immunoprecipitation, proximity ligation assays, subcellular fractionation, mitochondrial respiration analysis and echocardiography, a cardiolipin synthase-1 (Crsl1) knockout mouse model, and 2 v-ATPase knockout models. In addition, we assess whether a nutraceutical intervention targeting v-ATPase dysfunction can mitigate heart failure in aging mouse models and elderly people.

Our present findings reveal a sequence of events driving age-related cardiomyopathy: declining cardiac nicotinamide adenine dinucleotide levels impair v-ATPase-mediated lysosomal acidification by weakening the interaction between nicotinamide adenine dinucleotide-dependent glycolytic enzyme aldolase and v-ATPase. This disruption increases lysosomal membrane permeability by reducing lysosomal acidification, allowing cathepsin B to leak into mitochondria. There, cathepsin B disrupts mitochondrial CRLS1 (cardiolipin synthase I), impairing CL synthesis and remodeling. The resulting CL deficiency causes mitochondrial oxidative stress and programmed cell death, leading to mitochondrial and cardiac dysfunction. Genetic or chemical inhibition of v-ATPase and of CRLS1 in mouse models reproduce these age-related defects, highlighting their central roles in cardiac aging. Restoring nicotinamide adenine dinucleotide levels rescues lysosomal acidification and CL metabolism, protecting against age-related cardiomyopathy in rodents and humans.

Augmenting v-ATPase-mediated lysosomal acidification offers novel therapeutic strategies to combat age-related cardiomyopathy by rewiring CL homeostasis.