Altered UV resistance and UV mutational spectrum in repair-proficient murine fibroblasts expressing endonuclease V.
In previously reported studies, we transfected repair-proficient murine fibroblasts with the denV gene of bacteriophage T4 and showed that expression of encoded endonuclease V markedly enhanced cyclobutane pyrimidine dimer (CPD) repair and reduced the frequency of ultraviolet radiation (UV)-induced mutations. In the present studies, we compared the spectra of UV-induced mutations at the hprt locus in denV-transfected and control cells. A significant difference in mutation types was observed. While multiple base deletions and single base insertions were found in denV-transfected but not control cells, multiple tandem and non-tandem point mutations identified in control cells were absent in denV-transfected cells. When we compared colony survival following UV exposure in the two cell lines, it appeared that endonuclease V expression did not enhance UV resistance, instead denV-transfected cells had increased susceptibility to low fluences of UV. The effects of endonuclease V expression on UV resistance and on UV mutational spectrum are likely to be due both to the removal of CPDs and to the novel enzymatic activity of endonuclease V.
Kusewitt
D F
DF
Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque 87131, USA. dkusewitt@salud.unm.edu
Dyble
J
J
Sherburn
T E
TE
Ryan
S L
SL
Ji
J Y
JY
D000818:Animals; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D004260:DNA Repair / Q000235:genetics*; D043224:Deoxyribonuclease (Pyrimidine Dimer); D004706:Endodeoxyribonucleases / Q000235:genetics*; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology / Q000528:radiation effects*; D015870:Gene Expression / Q000235:genetics; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics / Q000528:radiation effects; D051379:Mice; D016296:Mutagenesis / Q000235:genetics / Q000528:radiation effects*; D009154:Mutation / Q000235:genetics / Q000528:radiation effects; D011836:Radiation Tolerance / Q000235:genetics / Q000528:radiation effects*; D014466:Ultraviolet Rays
D007041:Hypoxanthine Phosphoribosyltransferase; D004706:Endodeoxyribonucleases; D043224:Deoxyribonuclease (Pyrimidine Dimer)