Deficiency in the conserved ECHS1 gene causes Leigh syndrome by impairing mitochondrial respiration efficiency and suppressing ADRB2-PKA signaling

Deficiency in the short-chain enoyl-CoA hydratase 1 (ECHS1) gene causes Leigh syndrome (LS), a rare inherited metabolic disorder. Despite LS that arises as a result of inborn errors of energy metabolism, the specific contributions of ECHS1 deficiency to energy metabolism processes, developmental delay, and its mediated signaling mechanism remain unclear. Here, we identify a novel compound heterozygous variant [c.724G > A (p.Glu242Lys) and c.865G > A (Asp289Asn)] in the ECHS1 gene from a family of Han Chinese descent, with the affected individual displaying typical LS symptoms. The ECHS1 variants exhibit reduced 2-enoyl-CoA hydratase activity, resulting in a restricted ATP production rate, but the cellular ATP levels remains unchanged. ECHS1 deficiency also decreases cell viability and proliferation. Mechanistically, ECHS1 interacts with ADRB2, and its variants suppress the ADRB2/protein kinase A (PKA) signaling. Treatment with PKA signaling agonists or overexpression of PKA subunits in ECHS1-deficient cells can rescue the ATP production rate and restore cell viability. Additionally, the mitochondrial E3 ligase MUL1 mediates the ubiquitylation and degradation of ECHS1 protein variants. In conclusion, our study suggests that ECHS1 deficiency impairs mitochondrial respiratory efficiency, thereby lowering the ATP production rate, and reveals a promising therapeutic approach by targeting ADRB2/PKA signaling to combat ECHS1 deficiency-induced LS.