The human MLH1 cDNA complements DNA mismatch repair defects in Mlh1-deficient mouse embryonic fibroblasts.
The DNA mismatch repair gene hMLH1 is reported to function in mutation avoidance, cell cycle checkpoint control, the cytotoxicity of various DNA-damaging agents, and transcription-coupled nucleotide excision repair. Formal proof of the involvement of hMLH1 in these processes requires single gene complementation. We have stably expressed hMLH1 from a transfected cDNA in Mlh1-deficient mouse embryonic fibroblasts. Expression of hMLH1 restored normal levels of mPMS2 protein, reduced spontaneous base substitution and microsatellite mutations, increased sensitivity to the toxic effects of 6-thioguanine (6-TG), and restored 6-TG-induced cell cycle arrest. Our studies confirm that hMLH1 has an essential role in the maintenance of genomic stability and the potentiation of 6-TG cytotoxicity and provide a system for detailed structure/function analysis of the hMLH1 protein.
Buermeyer
A B
AB
Department of Molecular and Medical Genetics, Oregon Health Sciences University, Portland 97201-3098, USA.
Wilson-Van Patten
C
C
Baker
S M
SM
Liskay
R M
RM
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000633:toxicity; D020137:Base Pair Mismatch; D002352:Carrier Proteins; D002478:Cells, Cultured; D004260:DNA Repair / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics* / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism / Q000502:physiology; D016195:G2 Phase / Q000187:drug effects / Q000502:physiology; D006801:Humans; D051379:Mice; D000070957:MutL Protein Homolog 1; D009154:Mutation; D009363:Neoplasm Proteins / Q000172:deficiency* / Q000235:genetics* / Q000502:physiology; D009687:Nuclear Proteins; D013866:Thioguanine / Q000633:toxicity; D014162:Transfection