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Msh2 deficiency increases the mutation frequency in all parts of the mouse colon
Author(s) -
Zhang Shulin,
Lloyd Ruth,
Bowden Gregory,
Glickman Barry W.,
de Boer Johan G.
Publication year - 2002
Publication title -
environmental and molecular mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 87
eISSN - 1098-2280
pISSN - 0893-6692
DOI - 10.1002/em.10113
Subject(s) - msh2 , biology , frameshift mutation , mutation , haploinsufficiency , genetics , dna mismatch repair , mutant , gene , mlh1 , microbiology and biotechnology , cancer research , dna repair , phenotype
The Msh2 DNA mismatch repair gene is one of five genes implicated in the pathogenesis of hereditary nonpolyposis colorectal cancer (HNPCC). To address the possible mechanisms of the site‐specific occurrence of HNPCC, the effect of Msh2 deficiency on mutations in different parts of the colon was investigated using the BC‐1(lacI)/ Msh2 double transgenic mouse. Compared to the Msh2 +/+ mice, Msh2 ‐/‐ mice had an 8–9‐fold increase of mutation frequency (MF) in the lacI gene from the cecum and the proximal and distal colon. The mutational spectra were also significantly different between Msh2 +/+ and Msh 2 ‐/‐ mice, with a significant increase in the frequency of −1 frameshifts and G:C→A:T base substitutions in the repair‐deficient mice. However, in spite of the site‐specific predisposition of HNPCC in humans, we found no significant difference in the MF or mutation spectrum between the three parts of the colon in Msh2 +/+ , Msh2 +/‐ , or Msh2 ‐/‐ mice. In addition, 11 independent mutants harboring complex mutations within the lacI gene were recovered in the Msh2 ‐/‐ mice. Interestingly, while the Msh2 +/‐ mice displayed an overall MF similar to that observed in the wild‐type mice, sequencing revealed a significantly different mutational spectrum between Msh2 +/+ and Msh2 +/‐ mice, mainly characterized by an increase in −1 frameshifts. Due to the prevalence of frameshift mutations in HNPCC patients, this haploinsufficiency effect of the Msh2 gene in safeguarding genomic integrity may have important implications for human carrier status. Environ. Mol. Mutagen. 40:243–250, 2002. © 2002 Wiley‐Liss, Inc.