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UV wavelength-dependent regulation of transcription-coupled nucleotide excision repair in p53-deficient human cells.

Abstract：

:Nucleotide excision repair (NER) prevents skin cancer by eliminating highly genotoxic cyclobutane pyrimidine dimers (CPDs) induced in DNA by the UVB component of sunlight. NER consists of two distinct but overlapping subpathways, i.e., global NER, which removes CPD from the genome overall, and transcription-coupled NER (TCNER), which removes CPD uniquely from the transcribed strand of active genes. Previous investigations have clearly established that the p53 tumor suppressor plays a crucial role in the NER process. Here we used the ligation-mediated PCR technique to demonstrate, at nucleotide resolution along two chromosomal genes in human cells, that the requirement for functional p53 in TCNER, but not in global NER, depends on incident UV wavelength. Indeed, relative to an isogenic p53 wild-type counterpart, p53-deficient human lymphoblastoid strains were shown to remove CPD significantly less efficiently along both the transcribed and nontranscribed strands of the c-jun and hprt loci after exposure to polychromatic UVB (290-320 nm). However, in contrast, after irradiation with 254-nm UV, p53 deficiency engendered less efficient CPD repair only along the nontranscribed strands of these target genes. The revelation of this intriguing wavelength-dependent phenomenon reconciles an apparent conflict between previous studies which used either UVB or 254-nm UV to claim, respectively, that p53 is required for, or plays no role whatsoever in, TCNER of CPD. Furthermore, our finding highlights a major caveat in experimental photobiology by providing a prominent example where the extensively used "nonsolar" model mutagen 254-nm UV does not accurately replicate the effects of environmentally relevant UVB.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

Mathonnet G,Leger C,Desnoyers J,Drouin R,Therrien JP,Drobetsky EA

doi

10.1073/pnas.1232161100

keywords:

subject

Has Abstract

pub_date

2003-06-10 00:00:00

pages

7219-24

issue

eissn

0027-8424

issn

1091-6490

pii

1232161100

journal_volume

100

pub_type

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UV wavelength-dependent regulation of transcription-coupled nucleotide excision repair in p53-deficient human cells.