Loss of heterozygosity and point mutation at Aprt locus in T cells and fibroblasts of Pms2-/- mice.
Mice null for the Pms2 mismatch repair (MMR) gene exhibit a predisposition to lymphoma, microsatellite repeat instability, and failure of spermatogenesis. To study the role of Pms2 in the maintenance of in vivo genomic integrity in somatic cells, we characterized Aprt mutations in T cells and fibroblasts of 129 x C3H Pms2-/-Aprt+/- mice. The spontaneous frequency of DAP-resistant T lymphocytes, as a consequence of APRT-deficiency, was increased threefold. Point mutation, which accounted for less than 20% of the DAP(r) mutant clones in Pms2+/+ mice, was predominant in the mutant T cell clones from Pms2-/- mice. These point mutations were predominantly TA to CG transitions. Fibroblasts of Pms2-/- mice exhibited only a modest increase in the frequency of clones with point mutations, such that mitotic recombination was still the primary cause of APRT deficiency. Thus, the mutator phenotype as a consequence of PMS2 deficiency is tissue-dependent, which may be related to the tissue-specific tumor proneness of Pms2-/- mice.
Shao
Changshun
C
Department of Genetics, Rutgers, the State University of New Jersey, Piscataway, New Jersey, NJ 08854-8082, USA.
Yin
Moying
M
Deng
Li
L
Stambrook
Peter J
PJ
Doetschman
Thomas
T
Tischfield
Jay A
JA
D000228:Adenine Phosphoribosyltransferase / Q000235:genetics*; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000502:physiology*; D000818:Animals; D020137:Base Pair Mismatch; D001483:Base Sequence; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005260:Female; D005347:Fibroblasts / Q000201:enzymology; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D019656:Loss of Heterozygosity / Q000235:genetics*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000070976:Mismatch Repair Endonuclease PMS2; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics / Q000502:physiology*; D017354:Point Mutation; D013601:T-Lymphocytes / Q000201:enzymology
D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D000228:Adenine Phosphoribosyltransferase; D007041:Hypoxanthine Phosphoribosyltransferase; D000251:Adenosine Triphosphatases; C499533:Pms2 protein, mouse; D000070976:Mismatch Repair Endonuclease PMS2; D045643:DNA Repair Enzymes