title: Mitochondrial membrane potential decrease caused by loss of PINK1 is not due to proton leak, but to respiratory chain defects.
abstract: Mutations in PTEN-induced putative kinase 1 (PINK1) cause a recessive form of Parkinson's disease (PD). PINK1 is associated with mitochondrial quality control and its partial knock-down induces mitochondrial dysfunction including decreased membrane potential and increased vulnerability against mitochondrial toxins, but the exact function of PINK1 in mitochondria has not been investigated using cells with null expression of PINK1. Here, we show that loss of PINK1 caused mitochondrial dysfunction. In PINK1-deficient (PINK1(-/-)) mouse embryonic fibroblasts (MEFs), mitochondrial membrane potential and cellular ATP levels were decreased compared with those in littermate wild-type MEFs. However, mitochondrial proton leak, which reduces membrane potential in the absence of ATP synthesis, was not altered by loss of PINK1. Instead, activity of the respiratory chain, which produces the membrane potential by oxidizing substrates using oxygen, declined. H(2)O(2) production rate by PINK1(-/-) mitochondria was lower than PINK1(+/+) mitochondria as a consequence of decreased oxygen consumption rate, while the proportion (H(2)O(2) production rate per oxygen consumption rate) was higher. These results suggest that mitochondrial dysfunctions in PD pathogenesis are caused not by proton leak, but by respiratory chain defects.
authors.affiliation: Department of Biochemistry and Cell Biology, Institute of Development and Aging Sciences, Graduate School of Medicine, Nippon Medical School, 1-396 Kosugi-cho, Nakahara-ku, Kawasaki 211-8533, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Amo
authors.forename: Shigeto
authors.initials: S
authors.lastname: Sato
authors.forename: Shinji
authors.initials: S
authors.lastname: Saiki
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Wolf
authors.forename: Masaaki
authors.initials: M
authors.lastname: Toyomizu
authors.forename: Clement A
authors.initials: CA
authors.lastname: Gautier
authors.forename: Jie
authors.initials: J
authors.lastname: Shen
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ohta
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Hattori
mesh_terms: D000818:Animals; D019069:Cell Respiration / Q000235:genetics; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D028361:Mitochondrial Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D010300:Parkinson Disease / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011494:Protein Kinases / Q000172:deficiency* / Q000235:genetics; D011522:Protons; D000099202:PTEN-Induced Putative Kinase
chemical_list: D011494:Protein Kinases; D011522:Protons; D000099202:PTEN-Induced Putative Kinase