title: Mitochondrial ND5 gene variation associated with encephalomyopathy and mitochondrial ATP consumption.
abstract: Mitochondrial encephalomyopathy and lactic acidosis with strokelike episodes (MELAS) is a severe young onset stroke disorder without effective treatment. We have identified a MELAS patient harboring a 13528A-->G mitochondrial DNA (mtDNA) mutation in the Complex I ND5 gene. This mutation was homoplasmic in mtDNA from patient muscle and nearly homoplasmic (99.9%) in blood. Fibroblasts from the patient exhibited decreased mitochondrial membrane potential (Deltapsim) and increased lactate production, consistent with impaired mitochondrial function. Transfer of patient mtDNA to a new nuclear background using transmitochondrial cybrid fusions confirmed the pathogenicity of the 13528A-->G mutation; Complex I-linked respiration and Deltapsim were both significantly reduced in patient mtDNA cybrids compared with controls. Inhibition of the adenine nucleotide translocase or the F1F0-ATPase with bongkrekic acid or oligomycin caused a loss of potential in patient mtDNA cybrid mitochondria, indicating a requirement for glycolytically generated ATP to maintain Deltapsim. This was confirmed by inhibition of glycolysis with 2-deoxy-D-glucose, which caused depletion of ATP and mitochondrial depolarization in patient mtDNA cybrids. These data suggest that in response to impaired respiration due to the mtDNA mutation, mitochondria consume ATP to maintain Deltapsim, representing a potential pathophysiological mechanism in human mitochondrial disease.
authors.affiliation: Department of Biochemistry, La Trobe University, Melbourne 3086, Australia.
authors.forename: Matthew
authors.initials: M
authors.lastname: McKenzie
authors.forename: Danae
authors.initials: D
authors.lastname: Liolitsa
authors.forename: Natalya
authors.initials: N
authors.lastname: Akinshina
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Campanella
authors.forename: Sanjay
authors.initials: S
authors.lastname: Sisodiya
authors.forename: Ian
authors.initials: I
authors.lastname: Hargreaves
authors.forename: Niranjanan
authors.initials: N
authors.lastname: Nirmalananthan
authors.forename: Mary G
authors.initials: MG
authors.lastname: Sweeney
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Abou-Sleiman
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Wood
authors.forename: Michael G
authors.initials: MG
authors.lastname: Hanna
authors.forename: Michael R
authors.initials: MR
authors.lastname: Duchen
mesh_terms: D000140:Acidosis, Lactic / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000963:Antimetabolites / Q000494:pharmacology; D001865:Bongkrekic Acid / Q000494:pharmacology; D045744:Cell Line, Tumor; D004272:DNA, Mitochondrial / Q000235:genetics; D003847:Deoxyglucose / Q000494:pharmacology; D042967:Electron Transport Complex I / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006019:Glycolysis / Q000187:drug effects / Q000235:genetics; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000235:genetics; D008931:Mitochondria, Muscle / Q000235:genetics / Q000378:metabolism*; D017237:Mitochondrial Encephalomyopathies / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D009840:Oligomycins / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects / Q000235:genetics; D017354:Point Mutation; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020521:Stroke / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D000963:Antimetabolites; D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D009840:Oligomycins; D001865:Bongkrekic Acid; D000255:Adenosine Triphosphate; D003847:Deoxyglucose; C481838:MT-ND5 protein, human; D006180:Proton-Translocating ATPases; D042967:Electron Transport Complex I