Induction of the Mouse Ribonucleotide Reductase R1 and R2 Genes in Response to DNA Damage by UV Light

doi:10.1074/jbc.271.39.23698

Induction of the Mouse Ribonucleotide Reductase R1 and R2 Genes in Response to DNA Damage by UV Light*

From the Department of Medical Biochemistry and Biophysics, Umeå University, S-901 87 Umeå, Sweden

^§To whom correspondence should be addressed. Tel: 46-90-166742; Fax: 46-90-136310.

↵^‡ Present address: Cancer Research Group, Depts. of Pathology and Biochemistry, McMaster University, 1200 Main St. W., Hamilton, Ontario L8N 3Z5, Canada.

Abstract

Ribonucleotide reductase is responsible for the production of deoxyribonucleotides required for DNA synthesis and consists of two nonidentical subunits, proteins R1 and R2. Here we show that the R1 promoter can be induced up to 3-fold, and the R2 promoter is induced up to 10-fold by UV light in a dose-dependent manner. This was demonstrated using serum-starved, synchronized G₀/G₁ mouse fibroblast 3T3 cells stably transformed with different R1 and R2 promoter-luciferase reporter gene constructs. R2 promoter activation requires a minimal promoter, containing a TTTAAA element plus the transcription start, and either three upstream DNA-protein binding regions or one proximal, NF-Y binding region. This is different from proliferation-specific activation of the R2 promoter. Using Northern blotting we show a preferential accumulation of the minor, 1.6-kilobase R2 transcript in irradiated cells, whereas the levels of the major 2.1-kilobase transcript are unchanged. No R2 promoter activation was observed after treatment of mouse cells with agents reported to induce the ribonucleotide reductase genes in Saccharomyces cerevisiae such as hydroxyurea or methylmethane sulfonate. This indicates that activation of ribonucleotide reductase gene expression is specific for nucleotide excision repair in mammalian cells and not part of a general response to DNA damage.

Footnotes

↵* This work was supported by grants from the Swedish Natural Science Research Council and Lion's Cancer Research Foundation, Umeå University. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

kb

kilobase(s)

PBS

phosphatebuffered saline

DMEM

Dulbecco's modified Eagle's medium

nt

nucleotide.
↵²S. Björklund, D. Filatov, E. Skogman, M. Thelander, and L. Thelander, manuscript in preparation.
↵³L. Thelander, unpublished results.
- Received May 30, 1996.