The ubiquitin-interacting motif containing protein RAP80 interacts with BRCA1 and functions in DNA damage repair response.

Abstract

In this study, we examine the potential role of receptor-associated protein 80 (RAP80), a nuclear protein containing two ubiquitin-interacting motifs (UIM), in DNA damage response and double-strand break (DSB) repair. We show that following ionizing radiation and treatment with DNA-damaging agents, RAP80 translocates to discrete nuclear foci that colocalize with those of gamma-H2AX. The UIMs and the region of amino acids 204 to 304 are critical for the relocalization of RAP80 to ionizing radiation-induced foci (IRIF). These observations suggest that RAP80 becomes part of a DNA repair complex at the sites of IRIF. We also show that RAP80 forms a complex with the tumor repressor BRCA1 and that this interaction is mediated through the BRCA1 COOH-terminal repeats of BRCA1. The UIMs are not required for the interaction of RAP80 with BRCA1. Knockdown of RAP80 in HEK293 cells significantly reduced DSB-induced homology-directed recombination (HDR). Moreover, inhibition of RAP80 expression by small interfering RNA increased radiosensitivity, whereas increased radioresistance was observed in human breast cancer MCF-7 cells with overexpression of RAP80. Taken together, our data suggest that RAP80 plays an important role in DNA damage response signaling and HDR-mediated DSB repair. We further show that RAP80 can function as a substrate of the ataxia-telangiectasia mutated protein kinase in vitro, which phosphorylates RAP80 at Ser(205) and Ser(402). We show that this phosphorylation is not required for the migration of RAP80 to IRIF.

• Authors: Jun Yan, Yong-Sik Kim, Xiao-Ping Yang, Li-Ping Li, Grace Liao, Fen Xia, Anton M Jetten
• Journal: Cancer research (Cancer Res) Vol. 67 Issue 14 Pg. 6647-56 (Jul 15 2007) ISSN: 0008-5472 [Print] United States
• PMID: 17621610 (Publication Type: Journal Article, Research Support, N.I.H., Intramural)

Chemical References

• BRCA1 Protein
• BRCA1 protein, human
• Carrier Proteins
• Cell Cycle Proteins
• DNA-Binding Proteins
• Histone Chaperones
• Nuclear Proteins
• Tumor Suppressor Proteins
• UIMC1 protein, human
• Ubiquitin
• ATM protein, human
• Ataxia Telangiectasia Mutated Proteins
• Protein Serine-Threonine Kinases

Topics

• Amino Acid Motifs
• Amino Acid Sequence
• Ataxia Telangiectasia Mutated Proteins
• BRCA1 Protein (metabolism)
• Carrier Proteins (metabolism, physiology)
• Cell Cycle Proteins (physiology)
• Cell Line, Tumor
• DNA Damage
• DNA Repair
• DNA-Binding Proteins (physiology)
• Histone Chaperones
• Humans
• Molecular Sequence Data
• Nuclear Proteins (metabolism, physiology)
• Protein Serine-Threonine Kinases (physiology)
• Protein Structure, Tertiary
• Protein Transport
• Sequence Homology, Amino Acid
• Signal Transduction
• Tumor Suppressor Proteins (physiology)
• Ubiquitin (chemistry)