CoA‐dependent activation of mitochondrial acyl carrier protein links four neurodegenerative diseases

PKAN, CoPAN, MePAN, and PDH‐E2 deficiency share key phenotypic features but harbor defects in distinct metabolic processes. Selective damage to the globus pallidus occurs in these genetic neurodegenerative diseases, which arise from defects in CoA biosynthesis (PKAN, CoPAN), protein lipoylation (MePAN), and pyruvate dehydrogenase activity (PDH‐E2 deficiency). Overlap of their clinical features suggests a common molecular etiology, the identification of which is required to understand their pathophysiology and design treatment strategies. We provide evidence that CoA‐dependent activation of mitochondrial acyl carrier protein (mtACP) is a possible process linking these diseases through its effect on PDH activity. CoA is the source for the 4′‐phosphopantetheine moiety required for the posttranslational 4′‐phosphopantetheinylation needed to activate specific proteins. We show that impaired CoA homeostasis leads to decreased 4′‐phosphopantetheinylation of mtACP. This results in a decrease of the active form of mtACP, and in turn a decrease in lipoylation with reduced activity of lipoylated proteins, including PDH. Defects in the steps of a linked CoA‐mtACP‐PDH pathway cause similar phenotypic abnormalities. By chemically and genetically re‐activating PDH, these phenotypes can be rescued, suggesting possible treatment strategies for these diseases. Synopsis PKAN, CoPAN, MePAN and PDH‐E2 deficiency are neurodegenerative diseases that damage a specific area of the brain and in which mutated genes encode enzymes that play a role in intermediary metabolism. Restoring PDH activity rescues abnormalities caused by CoA biosynthesis defects in disease models. PKAN, CoPAN, MePAN and PDH‐E2 deficiency are linked by a metabolic pathway, which when disturbed causes a common phenotype. This pathway explains how impaired CoA biosynthesis (in PKAN/CoPAN) decreases mitochondrial acyl carrier protein activity, leading to decreased protein lipoylation (in MePAN) and decreased activity of PDH (in PDH‐E2 deficiency). Restoration of PDH activity, the final common step of the proposed linked metabolic pathway, rescues abnormalities caused by defects in CoA biosynthesis, the first step of the pathway. This pathway explains not only the overlapping clinical characteristics of the four diseases but also the brain iron accumulation in PKAN/CoPAN and the absence of iron in MePAN/PDH‐E2 deficiency. These results suggest disease‐specific treatment strategies. Graphical Abstract PKAN, CoPAN,