Depletion of TECPR2 leads to mitochondrial failure associated with neurodegeneration

HSAN9 is a rare progressive neurodegenerative disease in children linked to bi-allelic loss-of-function mutations in the TECPR2 gene. TECPR2 is a multi-domain protein harboring N-terminal WD repeats and C-terminal TECPR repeats, followed by a functional LIR motif that serves in phagophore targeting. Here, we demonstrate that the absence of TECPR2 results in impaired mitophagy, which can be restored by expressing its C-terminal domain. Accordingly, we uncover severe mitochondrial dysfunction and accumulation of mitochondrial content in primary fibroblasts derived from an HSAN9 patient, as well as in embryonic fibroblasts and dorsal root ganglia derived from an HSAN9 mouse model. Notably, these mitochondrial defects are mediated by mitochondrial stress through the activation of the integrated stress response (ISR), whereas mitochondrial function is restored by pharmaceutical or genetic suppression of ISR. Our findings establish a new connection between mitophagy and ISR in maintaining mitochondrial homeostasis during neurodegeneration. Abbreviations: Baf. A₁: bafilomycin A₁; CYCS: cytochrome c, somatic; HSAN9: hereditary sensory and autonomic neuropathy IX; ISR: integrated stress response; OA: oligomycin + antimycin A; ROS: reactive oxygen species; TECPR2: tectonin beta-propeller repeat containing 2.