Human mtDNA sublimons resemble rearranged mitochondrial genoms found in pathological states.

TitleHuman mtDNA sublimons resemble rearranged mitochondrial genoms found in pathological states.
Publication TypeJournal Article
Year of Publication2000
AuthorsKajander, OA, Rovio, AT, Majamaa, K, Poulton, J, Spelbrink, JN, Holt, IJ, Karhunen, PJ, Jacobs, HT
JournalHum Mol Genet
Volume9
Issue19
Pagination2821-35
Date Published2000 Nov 22
ISSN0964-6906
KeywordsAdult, Aged, Aged, 80 and over, Aging, Base Sequence, Chromosome Breakage, Cloning, Molecular, DNA, Mitochondrial, Electrophoresis, Agar Gel, Female, Fluorescence, Gene Dosage, Gene Duplication, Humans, Male, Middle Aged, Mitochondria, Mutagenesis, Myocardium, Nucleic Acid Conformation, Organ Specificity, Oxidative Stress, Polymerase Chain Reaction, Recombination, Genetic, Sequence Deletion, Tumor Cells, Cultured
Abstract

Sublimons, originally identified in plant mitochondria, are defined as rearranged mtDNA molecules present at very low levels. We have analysed the primary structures of sublimons found in human cells and tissues and estimated their abundance. Each tissue of a given individual contains a wide range of different sublimons and the most abundant species differ between tissues in a substantially systematic manner. Sublimons are undetectable in rho(0) cells, indicating that they are bona fide derivatives of mtDNA. They are most prominent in post-mitotic tissue subject to oxidative stress. Rearrangement break-points, often defined by short direct repeats, are scattered, but hotspot regions are clearly identifiable, notably near the end of the D-loop. The region between the replication origins is therefore frequently eliminated. One other hotspot region is located adjacent to a known site of protein binding, suggesting that recombination may be facilitated by protein-protein interactions. For a given primary rearrangement, both deleted and partially duplicated species can be detected. Although each sublimon is typically present at a low level, at most a few copies per cell, sublimon abundance in a given tissue can vary over three orders of magnitude between healthy individuals. Collectively, therefore, they can represent a non-negligible fraction of total mtDNA. Their structures are very similar to those of the rearranged molecules found in pathological states, such as adPEO and MNGIE; therefore, we propose that, as in plants, human mtDNA sublimons represent a pool of variant molecules that can become amplified under pathological conditions, thus contributing to cellular dysfunction.

DOI10.1093/hmg/9.19.2821
Alternate JournalHum. Mol. Genet.
Citation Key10.1093/hmg/9.19.2821
PubMed ID11092758
Grant ListMC_U105663140 / / Medical Research Council / United Kingdom