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MPV17 Loss Causes Deoxynucleotide Insufficiency and Slow DNA Replication in Mitochondria
Dalla Rosa, Ilaria (MRC Mill Hill Laboratory, London, United Kingdom)
Cámara, Yolanda (Vall d'Hebron Institut de Recerca. Laboratori de Trastorns Mitocondrials)
Durigon, Romina (MRC Mill Hill Laboratory)
Moss, Chloe F. (MRC Mill Hill Laboratory)
Vidoni, Sara (MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building)
Akman, Gokhan (MRC Mill Hill Laboratory)
Hunt, Lilian (MRC Mill Hill Laboratory)
Johnson, Mark A. (MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building)
Grocott, Sarah (Mitochondrial Genetics Group, Nuffield Department of Obstetrics and Gynaecology, Women's Centre, The John Radcliffe Hospital, Oxford, United Kingdom)
Wang, Liya (Department of Anatomy, Physiology and Biochemistry, The Swedish University of Agricultural Sciences, Biomedical Center)
Thorburn, David R. (Murdoch Childrens Research Institute and University of Melbourne Department of Paediatrics, Royal Children's Hospital)
Hirano, Michio (Department of Neurology, Columbia University Medical Center, New York, New York, United States of America)
Poulton, Joanna (Mitochondrial Genetics Group, Nuffield Department of Obstetrics and Gynaecology, Women's Centre, The John Radcliffe Hospital)
Taylor, Robert W. (Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, The Medical School, Newcastle upon Tyne)
Elgar, Greg (MRC Mill Hill Laboratory)
Martí, Ramon (Biomedical Network Research Centre on Rare Diseases, Instituto de Salud Carlos III)
Voshol, Peter (Institute of Metabolic Science, University of Cambridge)
Holt, Ian J. (MRC Mill Hill Laboratory, London)
Spinazzola, Antonella (MRC Mill Hill Laboratory)
Universitat Autònoma de Barcelona

Data: 2016
Resum: 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. Mitochondrial DNA depletion syndrome (MDS) is a genetically heterogeneous condition characterized by a decrease of mitochondrial DNA (mtDNA) copy number and decreased activities of respiratory chain enzymes. Depletion of mtDNA has been associated with mutations in several genes, which encode either proteins directly involved in mtDNA replication or factors regulating the homeostasis of the mitochondrial deoxynucleotide pool. However, for some genes the mechanism linking mutations and mtDNA depletion is not known. One such gene is MPV17, whose loss-of-function causes mtDNA abnormalities in human, mouse and yeast. Here we show that MPV17 dysfunction leads to a shortage of the precursors for DNA synthesis in the mitochondria, slowing DNA replication in the organelle. Not only does mtDNA copy number correlate with dNTP pool size in both mouse tissues and human cells, deoxynucleoside supplementation of the growth medium prevents depletion and restores mtDNA copy number in quiescent MPV17-deficient cells. Hence, our study links MPV17 deficiency, insufficiency of mitochondrial dNTPs, and slow replication in mitochondria to depletion of mtDNA manifesting in the human disease, and places MPV17-related disease firmly in the category of mtDNA disorders caused by deoxynucleotide perturbation. The prevention and reversal of mtDNA loss in MPV17 patient-derived cells identifies potential therapeutic strategy for a currently untreatable disease.
Nota: Número d'acord de subvenció EC/PIEF-GA-2009-255578
Nota: Número d'acord de subvenció MC_PC_13029
Drets: Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original. Creative Commons
Llengua: Anglès.
Document: article ; recerca ; publishedVersion
Publicat a: PLoS Genetics, Vol. 12 (january 2016) , ISSN 1553-7404

PMID: 26760297
DOI: 10.1371/journal.pgen.1005779


23 p, 4.0 MB

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