Mice expressing an error-prone DNA polymerase in mitochondria display elevated replication pausing and chromosomal breakage at fragile sites of mitochondrial DNA.

TitleMice expressing an error-prone DNA polymerase in mitochondria display elevated replication pausing and chromosomal breakage at fragile sites of mitochondrial DNA.
Publication TypeJournal Article
Year of Publication2009
AuthorsBailey, LJ, Cluett, TJ, Reyes, A, Prolla, TA, Poulton, J, Leeuwenburgh, C, Holt, IJ
JournalNucleic Acids Res
Volume37
Issue7
Pagination2327-35
Date Published2009 Apr
ISSN1362-4962
KeywordsAnimals, Chromosome Breakage, Chromosome Fragile Sites, DNA Polymerase gamma, DNA Replication, DNA, Mitochondrial, DNA-Directed DNA Polymerase, Female, Liver, Mice, Mice, Mutant Strains, Mitochondria, Progeria, Sequence Analysis, DNA, Single-Strand Specific DNA and RNA Endonucleases
Abstract

Expression of a proof-reading deficient form of mitochondrial DNA (mtDNA) polymerase gamma, POLG, causes early death accompanied by features of premature ageing in mouse. However, the mechanism of cellular senescence remains unresolved. In addition to high levels of point mutations of mtDNA, the POLG mutator mouse harbours linear mtDNAs. Using one- and two-dimensional agarose gel electrophoresis, we show that the linear mtDNAs derive from replication intermediates and are indicative of replication pausing and chromosomal breakage at the accompanying fragile sites. Replication fork arrest is not random but occurs at specific sites close to two cis-elements known as O(H) and O(L). Pausing at these sites may be enhanced in the case of exonuclease-deficient POLG owing to delayed resumption of DNA replication, or replisome instability. In either case, the mtDNA replication cycle is perturbed and this might explain the progeroid features of the POLG mutator mouse.

DOI10.1093/nar/gkp091
Alternate JournalNucleic Acids Res.
Citation Key10.1093/nar/gkp091
PubMed ID19244310
PubMed Central IDPMC2673436
Grant ListMC_U105663140 / / Medical Research Council / United Kingdom
R01 AG017994 / AG / NIA NIH HHS / United States
AG021905 / AG / NIA NIH HHS / United States
AG17994 / AG / NIA NIH HHS / United States
P30 AG028740 / AG / NIA NIH HHS / United States
AG21042 / AG / NIA NIH HHS / United States
R01 AG021042 / AG / NIA NIH HHS / United States
G0500695 / / Medical Research Council / United Kingdom
R01 AG021905 / AG / NIA NIH HHS / United States
/ / Wellcome Trust / United Kingdom