title: Loss of PLA2G6 leads to elevated mitochondrial lipid peroxidation and mitochondrial dysfunction.
abstract: The PLA2G6 gene encodes a group VIA calcium-independent phospholipase A2 beta enzyme that selectively hydrolyses glycerophospholipids to release free fatty acids. Mutations in PLA2G6 have been associated with disorders such as infantile neuroaxonal dystrophy, neurodegeneration with brain iron accumulation type II and Karak syndrome. More recently, PLA2G6 was identified as the causative gene in a subgroup of patients with autosomal recessive early-onset dystonia-parkinsonism. Neuropathological examination revealed widespread Lewy body pathology and the accumulation of hyperphosphorylated tau, supporting a link between PLA2G6 mutations and parkinsonian disorders. Here we show that knockout of the Drosophila homologue of the PLA2G6 gene, iPLA2-VIA, results in reduced survival, locomotor deficits and organismal hypersensitivity to oxidative stress. Furthermore, we demonstrate that loss of iPLA2-VIA function leads to a number of mitochondrial abnormalities, including mitochondrial respiratory chain dysfunction, reduced ATP synthesis and abnormal mitochondrial morphology. Moreover, we show that loss of iPLA2-VIA is strongly associated with increased lipid peroxidation levels. We confirmed our findings using cultured fibroblasts taken from two patients with mutations in the PLA2G6 gene. Similar abnormalities were seen including elevated mitochondrial lipid peroxidation and mitochondrial membrane defects, as well as raised levels of cytoplasmic and mitochondrial reactive oxygen species. Finally, we demonstrated that deuterated polyunsaturated fatty acids, which inhibit lipid peroxidation, were able to partially rescue the locomotor abnormalities seen in aged flies lacking iPLA2-VIA gene function, and restore mitochondrial membrane potential in fibroblasts from patients with PLA2G6 mutations. Taken together, our findings demonstrate that loss of normal PLA2G6 gene activity leads to lipid peroxidation, mitochondrial dysfunction and subsequent mitochondrial membrane abnormalities. Furthermore we show that the iPLA2-VIA knockout fly model provides a useful platform for the further study of PLA2G6-associated neurodegeneration.
authors.affiliation: 1 Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK 2 Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK k.kinghorn@ucl.ac.uk.
authors.forename: Kerri J
authors.initials: KJ
authors.lastname: Kinghorn
authors.affiliation: 1 Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK 2 Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK 3 Max Planck Institute for Biology of Ageing, Joseph-Stelzmann Str. 9b, D-50931, Cologne, Germany.
authors.forename: Jorge Iván
authors.initials: JI
authors.lastname: Castillo-Quan
authors.affiliation: 2 Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: Fernando
authors.initials: F
authors.lastname: Bartolome
authors.affiliation: 2 Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: Plamena R
authors.initials: PR
authors.lastname: Angelova
authors.affiliation: 1 Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK 2 Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: 4 Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Pope
authors.affiliation: 1 Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK 3 Max Planck Institute for Biology of Ageing, Joseph-Stelzmann Str. 9b, D-50931, Cologne, Germany.
authors.forename: Helena M
authors.initials: HM
authors.lastname: Cochemé
authors.affiliation: 1 Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK.
authors.forename: Shabana
authors.initials: S
authors.lastname: Khan
authors.affiliation: 5 Department of Family Medicine, Memorial University, St. John's, NL, Canada.
authors.forename: Shabnam
authors.initials: S
authors.lastname: Asghari
authors.affiliation: 2 Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: Kailash P
authors.initials: KP
authors.lastname: Bhatia
authors.affiliation: 2 Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: John
authors.initials: J
authors.lastname: Hardy
authors.affiliation: 2 Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: Andrey Y
authors.initials: AY
authors.lastname: Abramov
authors.affiliation: 1 Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK 3 Max Planck Institute for Biology of Ageing, Joseph-Stelzmann Str. 9b, D-50931, Cologne, Germany.
authors.forename: Linda
authors.initials: L
authors.lastname: Partridge
mesh_terms: D000818:Animals; D002460:Cell Line; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster; D005347:Fibroblasts / Q000378:metabolism; D055786:Gene Knockout Techniques; D054522:Group VI Phospholipases A2 / Q000235:genetics* / Q000378:metabolism; D054509:Group X Phospholipases A2 / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D015227:Lipid Peroxidation / Q000235:genetics*; D013058:Mass Spectrometry; D053078:Membrane Potential, Mitochondrial / Q000235:genetics; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology; D019636:Neurodegenerative Diseases / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029721:Drosophila Proteins; D054522:Group VI Phospholipases A2; D054509:Group X Phospholipases A2; C516475:PLA2G6 protein, human; C000600969:iPLA2-VIA protein, Drosophila
keywords: Drosophila; PLA2G6; infantile neuroaxonal dystrophy; neurodegeneration with brain iron accumulation