Defective mitochondrial DNA homeostasis in the substantia nigra in Parkinson disease

• Published in: Nature communications Vol. 7; no. 1; pp. 13548 - 11
• Main Authors: Dölle, Christian, Flønes, Irene, Nido, Gonzalo S., Miletic, Hrvoje, Osuagwu, Nelson, Kristoffersen, Stine, Lilleng, Peer K., Larsen, Jan Petter, Tysnes, Ole-Bjørn, Haugarvoll, Kristoffer, Bindoff, Laurence A., Tzoulis, Charalampos
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22.11.2016; Nature Publishing Group; Nature Portfolio
• Subjects: 13/1; 13/51; 14/63; 631/378/1689/1718; 631/378/2611; 631/80/642/333; Age; Aging; Base Sequence; Case-Control Studies; Clinical medicine; DNA Copy Number Variations; DNA, Mitochondrial - genetics; Gene Deletion; Gene Expression Regulation - physiology; Homeostasis; Hospitals; Humanities and Social Sciences; Humans; Hypotheses; Mitochondrial DNA; multidisciplinary; Mutagenesis; Mutation; Neurodegeneration; Neurons; Parkinson Disease - genetics; Parkinson Disease - metabolism; Parkinson Disease - pathology; Parkinson's disease; Pathogenesis; Pathology; Science; Science (multidisciplinary); Norway
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms13548

Increased somatic mitochondrial DNA (mtDNA) mutagenesis causes premature aging in mice, and mtDNA damage accumulates in the human brain with aging and neurodegenerative disorders such as Parkinson disease (PD). Here, we study the complete spectrum of mtDNA changes, including deletions, copy-number variation and point mutations, in single neurons from the dopaminergic substantia nigra and other brain areas of individuals with Parkinson disease and neurologically healthy controls. We show that in dopaminergic substantia nigra neurons of healthy individuals, mtDNA copy number increases with age, maintaining the pool of wild-type mtDNA population in spite of accumulating deletions. This upregulation fails to occur in individuals with Parkinson disease, however, resulting in depletion of the wild-type mtDNA population. By contrast, neuronal mtDNA point mutational load is not increased in Parkinson disease. Our findings suggest that dysregulation of mtDNA homeostasis is a key process in the pathogenesis of neuronal loss in Parkinson disease. Accumulated damage to mitochondrial DNA (mtDNA) occurs during the ageing process and neurodegenerative disease. Here, the authors show that mtDNA copy number increases in an age-dependent manner in substantia nigra of healthy individuals, but not in individuals with Parkinson disease.