title: Alkbh2 protects against lethality and mutation in primary mouse embryonic fibroblasts.
abstract: Alkylating agents modify DNA and RNA forming adducts that disrupt replication and transcription, trigger cell cycle checkpoints and/or initiate apoptosis. If left unrepaired, some of the damage can be cytotoxic and/or mutagenic. In Escherichia coli, the alkylation repair protein B (AlkB) provides one form of resistance to alkylating agents by eliminating mainly 1-methyladenine and 3-methylcytosine, thereby increasing survival and preventing mutation. To examine the biological role of the mammalian AlkB homologs Alkbh2 and Alkbh3, which both have similar enzymatic activities to that of AlkB, we evaluated the survival and mutagenesis of primary Big Blue mouse embryonic fibroblasts (MEFs) that had targeted deletions in the Alkbh2 or Alkbh3 genes. Both Alkbh2- and Alkbh3-deficient MEFs were ∼2-fold more sensitive to methyl methanesulfonate (MMS) induced cytotoxicity compared to the wild type control cells. Spontaneous mutant frequencies were similar for the wild type, Alkbh2-/- and Alkbh3-/- MEFs (average--1.3×10(-5)). However, despite the similar survival of the two mutant MEFs after MMS treatment, only the Alkbh2-deficient MEFs showed a statistically significant increase in mutant frequency compared to wild type MEFs after MMS treatment. Therefore, although both Alkbh2 and Alkbh3 can protect against MMS-induced cell death, only Alkbh2 shows statistically significant protection of MEF DNA against mutations following treatment with this exogenous methylating agent.
authors.affiliation: Biology Division, Beckman Research Institute, Irell and Manella Graduate School of Biological Sciences, City of Hope National Medical Center, 1450 East Duarte Road, Duarte, CA 91010, United States.
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Nay
authors.forename: Dong-Hyun
authors.initials: DH
authors.lastname: Lee
authors.forename: Steven E
authors.initials: SE
authors.lastname: Bates
authors.forename: Timothy R
authors.initials: TR
authors.lastname: O'Connor
mesh_terms: D000071499:AlkB Homolog 2, Alpha-Ketoglutarate-Dependent Dioxygenase; D000071500:AlkB Homolog 3, Alpha-Ketoglutarate-Dependent Dioxygenase; D000818:Animals; D001483:Base Sequence; D002869:Chromosome Aberrations; D045643:DNA Repair Enzymes / Q000235:genetics* / Q000378:metabolism; D049308:Dioxygenases / Q000235:genetics* / Q000378:metabolism; D053595:Embryonic Stem Cells; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D017353:Gene Deletion; D055786:Gene Knockout Techniques; D023061:Gene Order; D018390:Gene Targeting; D042822:Genomic Instability; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D009153:Mutagens / Q000494:pharmacology; D009154:Mutation / Q000187:drug effects
chemical_list: D009153:Mutagens; D008741:Methyl Methanesulfonate; D049308:Dioxygenases; D000071500:AlkB Homolog 3, Alpha-Ketoglutarate-Dependent Dioxygenase; C511887:Alkbh3 protein, mouse; D000071499:AlkB Homolog 2, Alpha-Ketoglutarate-Dependent Dioxygenase; C511886:Alkbh2 protein, mouse; D045643:DNA Repair Enzymes