Overexpression of the scaffold WD40 protein WRAP53β enhances the repair of and cell survival from DNA double-strand breaks.
Altered expression of the multifunctional protein WRAP53β (WD40 encoding RNA Antisense to p53), which targets repair factors to DNA double-strand breaks and factors involved in telomere elongation to Cajal bodies, is linked to carcinogenesis. While loss of WRAP53β function has been shown to disrupt processes regulated by this protein, the consequences of its overexpression remain unclear. Here we demonstrate that overexpression of WRAP53β disrupts the formation of and impairs the localization of coilin to Cajal bodies. At the same time, the function of this protein in the repair of DNA double-strand breaks is enhanced. Following irradiation, cells overexpressing WRAP53β exhibit more rapid clearance of phospho-histone H2AX (γH2AX), and more efficient homologous recombination and non-homologous end-joining, in association with fewer DNA breaks. Moreover, in these cells the ubiquitylation of damaged chromatin, which is known to facilitate the recruitment of repair factors and subsequent repair, is elevated. Knockdown of the ubiquitin ligase involved, ring-finger protein 8 (RNF8), which is recruited to DNA breaks by WRAP53β, attenuated this effect, suggesting that overexpression of WRAP53β leads to more rapid repair, as well as improved cell survival, by enhancing RNF8-mediated ubiquitylation at DNA breaks. Our present findings indicate that WRAP53β and RNF8 are rate-limiting factors in the repair of DNA double-strand breaks and raise the possibility that upregulation of WRAP53β may contribute to genomic stability in and survival of cancer cells.
Cancer Centrum Karolinska, Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
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Rassoolzadeh
Cancer Centrum Karolinska, Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
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Böhm
Cancer Centrum Karolinska, Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
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Hedström
Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
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Gad
Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
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Helleday
Cancer Centrum Karolinska, Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
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Henriksson
Cancer Centrum Karolinska, Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
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Farnebo
D045744:Cell Line, Tumor; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism; D020541:Coiled Bodies / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D018832:Molecular Chaperones; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010006:Osteoblasts / Q000378:metabolism* / Q000473:pathology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D059767:Recombinational DNA Repair; D015398:Signal Transduction; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism; D016615:Telomere / Q000737:chemistry / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D054875:Ubiquitination
D002843:Chromatin; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D020033:Protein Isoforms; D034741:RNA, Small Interfering; C486521:RNF8 protein, human; C068921:p80-coilin; D004247:DNA; D044767:Ubiquitin-Protein Ligases; D019098:Telomerase; C535133:WRAP53 protein, human