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Nucleic Acids Res. Jun 15, 1998; 26(12): 2859–2864.
PMCID: PMC147643

Overexpression of Rad51 protein stimulates homologous recombination and increases resistance of mammalian cells to ionizing radiation.


Rad51 proteins share both structural and functional homologies with the bacterial recombinase RecA. The human Rad51 (HsRad51) is able to catalyse strand exchange between homologous DNA molecules in vitro . However the biological functions of Rad51 in mammals are largely unknown. In order to address this question, we have cloned hamster Rad51 cDNA and overexpressed the corresponding protein in CHO cells. We found that 2-3-fold overexpression of the protein stimulated the homologous recombination between integrated genes by 20-fold indicating that Rad51 is a functional and key enzyme of an intrachromosomal recombination pathway. Cells overexpressing Rad51 were resistant to ionizing radiation when irradiated in late S/G2phase of the cell cycle. This suggests that Rad51 participate in the repair of double-strand breaks most likely by homologous recombination involving sister chromatids formed after the S phase.

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Selected References

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  • Thompson LH. Evidence that mammalian cells possess homologous recombinational repair pathways. Mutat Res. 1996 Jun 12;363(2):77–88. [PubMed]
  • Hellgren D. Mutagen-induced recombination in mammalian cells in vitro. Mutat Res. 1992 Dec 1;284(1):37–51. [PubMed]
  • Li J, Ayyadevera R, Shmookler Reis RJ. Carcinogens stimulate intrachromosomal homologous recombination at an endogenous locus in human diploid fibroblasts. Mutat Res. 1997 Dec;385(3):173–193. [PubMed]
  • Zhang LH, Jenssen D. Studies on intrachromosomal recombination in SP5/V79 Chinese hamster cells upon exposure to different agents related to carcinogenesis. Carcinogenesis. 1994 Oct;15(10):2303–2310. [PubMed]
  • Whitmore GF, Varghese AJ, Gulyas S. Cell cycle responses of two X-ray sensitive mutants defective in DNA repair. Int J Radiat Biol. 1989 Nov;56(5):657–665. [PubMed]
  • Brendel V, Brocchieri L, Sandler SJ, Clark AJ, Karlin S. Evolutionary comparisons of RecA-like proteins across all major kingdoms of living organisms. J Mol Evol. 1997 May;44(5):528–541. [PubMed]
  • Aboussekhra A, Chanet R, Adjiri A, Fabre F. Semidominant suppressors of Srs2 helicase mutations of Saccharomyces cerevisiae map in the RAD51 gene, whose sequence predicts a protein with similarities to procaryotic RecA proteins. Mol Cell Biol. 1992 Jul;12(7):3224–3234. [PMC free article] [PubMed]
  • Basile G, Aker M, Mortimer RK. Nucleotide sequence and transcriptional regulation of the yeast recombinational repair gene RAD51. Mol Cell Biol. 1992 Jul;12(7):3235–3246. [PMC free article] [PubMed]
  • Shinohara A, Ogawa H, Ogawa T. Rad51 protein involved in repair and recombination in S. cerevisiae is a RecA-like protein. Cell. 1992 May 1;69(3):457–470. [PubMed]
  • Sung P, Robberson DL. DNA strand exchange mediated by a RAD51-ssDNA nucleoprotein filament with polarity opposite to that of RecA. Cell. 1995 Aug 11;82(3):453–461. [PubMed]
  • Namsaraev E, Berg P. Characterization of strand exchange activity of yeast Rad51 protein. Mol Cell Biol. 1997 Sep;17(9):5359–5368. [PMC free article] [PubMed]
  • New JH, Sugiyama T, Zaitseva E, Kowalczykowski SC. Rad52 protein stimulates DNA strand exchange by Rad51 and replication protein A. Nature. 1998 Jan 22;391(6665):407–410. [PubMed]
  • Shinohara A, Ogawa T. Stimulation by Rad52 of yeast Rad51-mediated recombination. Nature. 1998 Jan 22;391(6665):404–407. [PubMed]
  • Sung P. Yeast Rad55 and Rad57 proteins form a heterodimer that functions with replication protein A to promote DNA strand exchange by Rad51 recombinase. Genes Dev. 1997 May 1;11(9):1111–1121. [PubMed]
  • Sugiyama T, Zaitseva EM, Kowalczykowski SC. A single-stranded DNA-binding protein is needed for efficient presynaptic complex formation by the Saccharomyces cerevisiae Rad51 protein. J Biol Chem. 1997 Mar 21;272(12):7940–7945. [PubMed]
  • Yoshimura Y, Morita T, Yamamoto A, Matsushiro A. Cloning and sequence of the human RecA-like gene cDNA. Nucleic Acids Res. 1993 Apr 11;21(7):1665–1665. [PMC free article] [PubMed]
  • Shinohara A, Ogawa H, Matsuda Y, Ushio N, Ikeo K, Ogawa T. Cloning of human, mouse and fission yeast recombination genes homologous to RAD51 and recA. Nat Genet. 1993 Jul;4(3):239–243. [PubMed]
  • Bezzubova O, Shinohara A, Mueller RG, Ogawa H, Buerstedde JM. A chicken RAD51 homologue is expressed at high levels in lymphoid and reproductive organs. Nucleic Acids Res. 1993 Apr 11;21(7):1577–1580. [PMC free article] [PubMed]
  • Ogawa T, Yu X, Shinohara A, Egelman EH. Similarity of the yeast RAD51 filament to the bacterial RecA filament. Science. 1993 Mar 26;259(5103):1896–1899. [PubMed]
  • Benson FE, Stasiak A, West SC. Purification and characterization of the human Rad51 protein, an analogue of E. coli RecA. EMBO J. 1994 Dec 1;13(23):5764–5771. [PMC free article] [PubMed]
  • Baumann P, Benson FE, West SC. Human Rad51 protein promotes ATP-dependent homologous pairing and strand transfer reactions in vitro. Cell. 1996 Nov 15;87(4):757–766. [PubMed]
  • Baumann P, West SC. The human Rad51 protein: polarity of strand transfer and stimulation by hRP-A. EMBO J. 1997 Sep 1;16(17):5198–5206. [PMC free article] [PubMed]
  • Gupta RC, Bazemore LR, Golub EI, Radding CM. Activities of human recombination protein Rad51. Proc Natl Acad Sci U S A. 1997 Jan 21;94(2):463–468. [PMC free article] [PubMed]
  • Benson FE, Baumann P, West SC. Synergistic actions of Rad51 and Rad52 in recombination and DNA repair. Nature. 1998 Jan 22;391(6665):401–404. [PubMed]
  • Haaf T, Golub EI, Reddy G, Radding CM, Ward DC. Nuclear foci of mammalian Rad51 recombination protein in somatic cells after DNA damage and its localization in synaptonemal complexes. Proc Natl Acad Sci U S A. 1995 Mar 14;92(6):2298–2302. [PMC free article] [PubMed]
  • Barlow AL, Benson FE, West SC, Hultén MA. Distribution of the Rad51 recombinase in human and mouse spermatocytes. EMBO J. 1997 Sep 1;16(17):5207–5215. [PMC free article] [PubMed]
  • Lim DS, Hasty P. A mutation in mouse rad51 results in an early embryonic lethal that is suppressed by a mutation in p53. Mol Cell Biol. 1996 Dec;16(12):7133–7143. [PMC free article] [PubMed]
  • Tsuzuki T, Fujii Y, Sakumi K, Tominaga Y, Nakao K, Sekiguchi M, Matsushiro A, Yoshimura Y, MoritaT Targeted disruption of the Rad51 gene leads to lethality in embryonic mice. Proc Natl Acad Sci U S A. 1996 Jun 25;93(13):6236–6240. [PMC free article] [PubMed]
  • Sonoda E, Sasaki MS, Buerstedde JM, Bezzubova O, Shinohara A, Ogawa H, Takata M, Yamaguchi-Iwai Y, Takeda S. Rad51-deficient vertebrate cells accumulate chromosomal breaks prior to cell death. EMBO J. 1998 Jan 15;17(2):598–608. [PMC free article] [PubMed]
  • Vindeløv LL, Christensen IJ, Nissen NI. A detergent-trypsin method for the preparation of nuclei for flow cytometric DNA analysis. Cytometry. 1983 Mar;3(5):323–327. [PubMed]
  • Chen H, Pomeroy-Cloney L, Bjerknes M, Tam J, Jay E. The influence of adenine-rich motifs in the 3' portion of the ribosome binding site on human IFN-gamma gene expression in Escherichia coli. J Mol Biol. 1994 Jul 1;240(1):20–27. [PubMed]
  • Herzing LB, Meyn MS. Novel lacZ-based recombination vectors for mammalian cells. Gene. 1993 Dec 31;137(2):163–169. [PubMed]
  • Meyn MS. High spontaneous intrachromosomal recombination rates in ataxia-telangiectasia. Science. 1993 May 28;260(5112):1327–1330. [PubMed]
  • Kawai S, Nishizawa M. New procedure for DNA transfection with polycation and dimethyl sulfoxide. Mol Cell Biol. 1984 Jun;4(6):1172–1174. [PMC free article] [PubMed]
  • Capizzi RL, Jameson JW. A table for the estimation of the spontaneous mutation rate of cells in culture. Mutat Res. 1973 Jan;17(1):147–148. [PubMed]
  • Bertrand P, Rouillard D, Boulet A, Levalois C, Soussi T, Lopez BS. Increase of spontaneous intrachromosomal homologous recombination in mammalian cells expressing a mutant p53 protein. Oncogene. 1997 Mar 6;14(9):1117–1122. [PubMed]
  • Park MS. Expression of human RAD52 confers resistance to ionizing radiation in mammalian cells. J Biol Chem. 1995 Jun 30;270(26):15467–15470. [PubMed]
  • Hellgren D, Luthman H, Lambert B. Induced recombination between duplicated neo genes stably integrated in the genome of CHO cells. Mutat Res. 1989 Jan;210(1):197–206. [PubMed]
  • Jeggo PA. DNA-PK: at the cross-roads of biochemistry and genetics. Mutat Res. 1997 Jun 9;384(1):1–14. [PubMed]
  • Xia SJ, Shammas MA, Shmookler Reis RJ. Elevated recombination in immortal human cells is mediated by HsRAD51 recombinase. Mol Cell Biol. 1997 Dec;17(12):7151–7158. [PMC free article] [PubMed]
  • Lee SE, Mitchell RA, Cheng A, Hendrickson EA. Evidence for DNA-PK-dependent and -independent DNA double-strand break repair pathways in mammalian cells as a function of the cell cycle. Mol Cell Biol. 1997 Mar;17(3):1425–1433. [PMC free article] [PubMed]
  • Kadyk LC, Hartwell LH. Sister chromatids are preferred over homologs as substrates for recombinational repair in Saccharomyces cerevisiae. Genetics. 1992 Oct;132(2):387–402. [PMC free article] [PubMed]
  • Osman F, Subramani S. Double-strand break-induced recombination in eukaryotes. Prog Nucleic Acid Res Mol Biol. 1998;58:263–299. [PubMed]

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