Mitochondrial components secretion in extracellular vesicles promotes alveolar epithelial mitochondrial quality control.

The quality control network in type 2 alveolar epithelial cells (AEC2s) is essential to respond to intrinsic and extrinsic challenges. However, the mechanisms that regulate AEC2 mitochondrial homeostasis remain unclear understood. Here, we report a role of G protein-coupled receptor class C group 5 member A (GPRC5A) in mitochondrial quality control in AEC2s through promoting mitochondrial secretion in extracellular vesicles (EVs). Utilizing mice models, we demonstrate that the disruption of GPRC5A specifically in AEC2s aggravates lung injuries. We further observe that GPRC5A deficiency in AEC2s reduces secretion of mitochondrial components in small-EVs and disrupts mitochondrial functions both in vitro and in vivo. Mechanistically, we determine that the GPRC5A-MIRO2 pathway facilitates the transfer of mitochondrial fragments into late endosomes. Collectively, our findings provide evidence of the shedding of mitochondrial components dependent on GPRC5A as a pathway of mitochondrial quality control in AEC2s, which is crucial in the maintenance of epithelial physiological activities and lung tissue homeostasis.