Introduction of human telomerase reverse transcriptase to normal human fibroblasts enhances DNA repair capacity.
OBJECTIVE
From numerous reports on proteins involved in DNA repair and telomere maintenance that physically associate with human telomerase reverse transcriptase (hTERT), we inferred that hTERT/telomerase might play a role in DNA repair. We investigated this possibility in normal human oral fibroblasts (NHOF) with and without ectopic expression of hTERT/telomerase.


METHODS
To study the effect of hTERT/telomerase on DNA repair, we examined the mutation frequency rate, host cell reactivation rate, nucleotide excision repair capacity, and DNA end-joining activity of NHOF and NHOF capable of expressing hTERT/telomerase (NHOF-T). NHOF-T was obtained by transfecting NHOF with hTERT plasmid.


RESULTS
Compared with parental NHOF and NHOF transfected with empty vector (NHOF-EV), we found that (a) the N-methyl-N'-nitro-N-nitrosoguanidine-induced mutation frequency of an exogenous shuttle vector was reduced in NHOF-T, (b) the host cell reactivation rate of N-methyl-N'-nitro-N-nitrosoguanidine-damaged plasmids was significantly faster in NHOF-T; (c) the nucleotide excision repair of UV-damaged DNA in NHOF-T was faster, and (d) the DNA end-joining capacity in NHOF-T was enhanced. We also found that the above enhanced DNA repair activities in NHOF-T disappeared when the cells lost the capacity to express hTERT/telomerase.


CONCLUSIONS
These results indicated that hTERT/telomerase enhances DNA repair activities in NHOF. We hypothesize that hTERT/telomerase accelerates DNA repair by recruiting DNA repair proteins to the damaged DNA sites.
Shin
Ki-Hyuk
KH
School of Dentistry, University of California, Los Angeles, California 90095, USA.
Kang
Mo K
MK
Dicterow
Erica
E
Kameta
Ayako
A
Baluda
Marcel A
MA
Park
No-Hee
NH
D015139:Blotting, Southern; D002478:Cells, Cultured; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004249:DNA Damage; D004252:DNA Mutational Analysis; D004260:DNA Repair; D004268:DNA-Binding Proteins; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D009154:Mutation; D012333:RNA, Messenger / Q000378:metabolism; D019098:Telomerase / Q000378:metabolism*; D014162:Transfection; D014466:Ultraviolet Rays
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D008769:Methylnitronitrosoguanidine; D004247:DNA; D008156:Luciferases; D019098:Telomerase