Mitochondria: A crossroads for lipid metabolism defect in neurodegeneration with brain iron accumulation diseases

摘要

Neurodegeneration with brain iron accumulation (NBIA) comprises a group of brain iron deposition syndromes that lead to mixed extrapyramidal features and progressive dementia. Exact pathologic mechanism of iron deposition in NBIA remains unknown. However, it is becoming increasingly evident that many neurodegenerative diseases are hallmarked by metabolic dysfunction that often involves altered lipid profile. Among the identified disease genes, four encode for proteins localized in mitochondria, which are directly or indirectly implicated in lipid metabolism: PANK2, CoASY, PLA2G6 and C19orf12. Mutations in PANIQ and CoASY, both implicated in CoA biosynthesis that acts as a fatty acyl carrier, lead, respectively, to PKAN and CoPAN forms of NBIA. Mutations in PL42G6, which plays a key role in the biosynthesis and remodeling of membrane phospholipids including cardiolipin, lead to PLAN. Mutations in Cl9orf12 lead to MPAN, a syndrome similar to that caused by mutations in PANK2 and PLA2G6. Although the function of Cl9orf12 is largely unknown, experimental data suggest its implication in mitochondrial homeostasis and lipid metabolism. Altogether, the identified mutated proteins localized in mitochondria and associated with different NBIA forms support the concept that dysfunctions in mitochondria and lipid metabolism play a crucial role in the pathogenesis of NBIA.