Repair deficient mice reveal mABH2 as the primary oxidative demethylase for repairing 1meA and 3meC lesions in DNA.
Two human homologs of the Escherichia coli AlkB protein, denoted hABH2 and hABH3, were recently shown to directly reverse 1-methyladenine (1meA) and 3-methylcytosine (3meC) damages in DNA. We demonstrate that mice lacking functional mABH2 or mABH3 genes, or both, are viable and without overt phenotypes. Neither were histopathological changes observed in the gene-targeted mice. However, in the absence of any exogenous exposure to methylating agents, mice lacking mABH2, but not mABH3 defective mice, accumulate significant levels of 1meA in the genome, suggesting the presence of a biologically relevant endogenous source of methylating agent. Furthermore, embryonal fibroblasts from mABH2-deficient mice are unable to remove methyl methane sulfate (MMS)-induced 1meA from genomic DNA and display increased cytotoxicity after MMS exposure. In agreement with these results, we found that in vitro repair of 1meA and 3meC in double-stranded DNA by nuclear extracts depended primarily, if not solely, on mABH2. Our data suggest that mABH2 and mABH3 have different roles in the defense against alkylating agents.
Ringvoll
Jeanette
J
Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet-Radiumhospitalet HF, University of Oslo, Oslo, Norway.
Nordstrand
Line M
LM
Vågbø
Cathrine B
CB
Talstad
Vivi
V
Reite
Karen
K
Aas
Per Arne
PA
Lauritzen
Knut H
KH
Liabakk
Nina Beate
NB
Bjørk
Alexandra
A
Doughty
Richard William
RW
Falnes
Pål Ø
PØ
Krokan
Hans E
HE
Klungland
Arne
A
D000225:Adenine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D000071499:AlkB Homolog 2, Alpha-Ketoglutarate-Dependent Dioxygenase; D000071500:AlkB Homolog 3, Alpha-Ketoglutarate-Dependent Dioxygenase; D000483:Alleles; D000818:Animals; D002460:Cell Line; D003596:Cytosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D049308:Dioxygenases; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D015394:Molecular Structure; D014018:Tissue Distribution
D004268:DNA-Binding Proteins; C036386:3-methylcytosine; C008407:1-methyladenine; D003596:Cytosine; D004247:DNA; D049308:Dioxygenases; C486439:ALKBH3 protein, human; D000071500:AlkB Homolog 3, Alpha-Ketoglutarate-Dependent Dioxygenase; C486440:ALKBH2 protein, human; D000071499:AlkB Homolog 2, Alpha-Ketoglutarate-Dependent Dioxygenase; C511886:Alkbh2 protein, mouse; D045643:DNA Repair Enzymes; D000225:Adenine