Abstract
A variety of cellular proteins has the ability to recognize DNA lesions induced by the anti-cancer drug cisplatin, with diverse consequences on their repair and on the therapeutic effectiveness of this drug. We report a novel gene involved in the cell response to cisplatin in vertebrates. The RDM1 gene (for RAD52 Motif 1) was identified while searching databases for sequences showing similarities to RAD52, a protein involved in homologous recombination and DNA double-strand break repair. Ablation of RDM1 in the chicken B cell line DT40 led to a more than 3-fold increase in sensitivity to cisplatin. However, RDM1-/- cells were not hypersensitive to DNA damages caused by ionizing radiation, UV irradiation, or the alkylating agent methylmethane sulfonate. The RDM1 protein displays a nucleic acid binding domain of the RNA recognition motif (RRM) type. By using gel-shift assays and electron microscopy, we show that purified, recombinant chicken RDM1 protein interacts with single-stranded DNA as well as double-stranded DNA, on which it assembles filament-like structures. Notably, RDM1 recognizes DNA distortions induced by cisplatin-DNA adducts in vitro. Finally, human RDM1 transcripts are abundant in the testis, suggesting a possible role during spermatogenesis.
Highlights
The cytotoxic activity of cisplatin (cis-diamminedichloroplatinum (II)) is thought to be due to its interaction with purine bases of our chromosomes and the various DNA adducts that ensue, including monoadducts and interstrand cross-links (ICLs),1 as well as the predominant (1,3- and 1,2-) intrastrand
While searching this database for candidate genes involved in DNA repair and/or recombination, we identified an EST whose deduced aa sequence displayed partial similarity to an N-terminal region of the RAD52 protein
We have shown that ablation of RDM1 in chicken DT40 cells leads to an increase of their sensitivity to cisplatin
Summary
The cytotoxic activity of cisplatin (cis-diamminedichloroplatinum (II)) is thought to be due to its interaction with purine bases of our chromosomes and the various DNA adducts that ensue, including monoadducts and interstrand cross-links (ICLs),1 as well as the predominant (1,3- and 1,2-) intrastrand. The RDM1 gene (for RAD52 Motif 1) was identified while searching databases for sequences showing similarities to RAD52, a protein involved in homologous recombination and DNA double-strand break repair. By using gel-shift assays and electron microscopy, we show that purified, recombinant chicken RDM1 protein interacts with single-stranded DNA as well as doublestranded DNA, on which it assembles filament-like structures.
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