Strand specificity for UV-induced DNA repair and mutations in the Chinese hamster HPRT gene.
DNA excision repair modulates the mutagenic effect of many genotoxic agents. The recently observed strand specificity for removal of UV-induced cyclobutane dimers from actively transcribed genes in mammalian cells could influence the nature and distribution of mutations in a particular gene. To investigate this, we have analyzed UV-induced DNA repair and mutagenesis in the same gene, i.e. the hypoxanthine phosphoribosyl-transferase (hprt) gene. In 23 hprt mutants from V79 Chinese hamster cells induced by 2 J/m2 UV we found a strong strand bias for mutation induction: assuming that pre-mutagenic lesions occur at dipyrimidine sequences, 85% of the mutations could be attributed to lesions in the nontranscribed strand. Analysis of DNA repair in the hprt gene revealed that more than 90% of the cyclobutane dimers were removed from the transcribed strand within 8 hours after irradiation with 10 J/m2 UV, whereas virtually no dimer removal could be detected from the nontranscribed strand even up to 24 hr after UV. These data present the first proof that strand specific repair of DNA lesions in an expressed mammalian gene is associated with a strand specificity for mutation induction.
Department of Radiation Genetics and Chemical Mutagenesis, State University of Leiden, The Netherlands.
H
H
Vrieling
J
J
Venema
M L
ML
van Rooyen
A
A
van Hoffen
P
P
Menichini
M Z
MZ
Zdzienicka
J W
JW
Simons
L H
LH
Mullenders
A A
AA
van Zeeland
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000528:radiation effects; D004260:DNA Repair; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D007700:Kinetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D012150:Polymorphism, Restriction Fragment Length; D014466:Ultraviolet Rays
D004247:DNA; D007041:Hypoxanthine Phosphoribosyltransferase