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PLoS Genet. 2016 Jan 13;12(1):e1005779. doi: 10.1371/journal.pgen.1005779. eCollection 2016 Jan.

MPV17 Loss Causes Deoxynucleotide Insufficiency and Slow DNA Replication in Mitochondria.

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MRC Mill Hill Laboratory, London, United Kingdom.
Laboratory of Mitochondrial Disorders, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Catalonia.
Biomedical Network Research Centre on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain.
MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Cambridge, United Kingdom.
Mitochondrial Genetics Group, Nuffield Department of Obstetrics and Gynaecology, Women's Centre, The John Radcliffe Hospital, Oxford, United Kingdom.
Department of Anatomy, Physiology and Biochemistry, The Swedish University of Agricultural Sciences, Biomedical Center, Uppsala, Sweden.
Murdoch Childrens Research Institute and University of Melbourne Department of Paediatrics, Royal Children's Hospital, Flemington Road, Parkville, Victoria, Australia.
Department of Neurology, Columbia University Medical Center, New York, New York, United States of America.
Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, The Medical School, Newcastle upon Tyne, United Kingdom.
Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom.


MPV17 is a mitochondrial inner membrane protein whose dysfunction causes mitochondrial DNA abnormalities and disease by an unknown mechanism. Perturbations of deoxynucleoside triphosphate (dNTP) pools are a recognized cause of mitochondrial genomic instability; therefore, we determined DNA copy number and dNTP levels in mitochondria of two models of MPV17 deficiency. In Mpv17 ablated mice, liver mitochondria showed substantial decreases in the levels of dGTP and dTTP and severe mitochondrial DNA depletion, whereas the dNTP pool was not significantly altered in kidney and brain mitochondria that had near normal levels of DNA. The shortage of mitochondrial dNTPs in Mpv17-/- liver slows the DNA replication in the organelle, as evidenced by the elevated level of replication intermediates. Quiescent fibroblasts of MPV17-mutant patients recapitulate key features of the primary affected tissue of the Mpv17-/- mice, displaying virtual absence of the protein, decreased dNTP levels and mitochondrial DNA depletion. Notably, the mitochondrial DNA loss in the patients' quiescent fibroblasts was prevented and rescued by deoxynucleoside supplementation. Thus, our study establishes dNTP insufficiency in the mitochondria as the cause of mitochondrial DNA depletion in MPV17 deficiency, and identifies deoxynucleoside supplementation as a potential therapeutic strategy for MPV17-related disease. Moreover, changes in the expression of factors involved in mitochondrial deoxynucleotide homeostasis indicate a remodeling of nucleotide metabolism in MPV17 disease models, which suggests mitochondria lacking functional MPV17 have a restricted purine mitochondrial salvage pathway.

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