Bi-directional routing of DNA mismatch repair protein human exonuclease 1 to replication foci and DNA double strand breaks

• Published in: DNA repair Vol. 10; no. 1; pp. 73 - 86
• Main Authors: Liberti, Sascha E., Andersen, Sofie D., Wang, Jing, May, Alfred, Miron, Simona, Perderiset, Mylene, Keijzers, Guido, Nielsen, Finn C., Charbonnier, Jean-Baptiste, Bohr, Vilhelm A., Rasmussen, Lene J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02-01-2011; Elsevier
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Amino Acid Motifs; Amino Acid Substitution; Animals; Bacteriology; Biochemistry, Molecular Biology; Biological and medical sciences; DNA - genetics; DNA - metabolism; DNA Breaks, Double-Stranded - radiation effects; DNA mismatch repair; DNA Mismatch Repair - physiology; DNA Mismatch Repair - radiation effects; DNA Repair Enzymes - genetics; DNA Repair Enzymes - metabolism; DNA Repair Enzymes - radiation effects; DNA Replication - physiology; DNA Replication - radiation effects; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Double strand break; Exodeoxyribonucleases - genetics; Exodeoxyribonucleases - metabolism; Exodeoxyribonucleases - radiation effects; Fundamental and applied biological sciences. Psychology; Growth, nutrition, cell differenciation; HeLa Cells; hEXO1; Humans; Lasers - adverse effects; Life Sciences; Mice; Microbiology; Molecular and cellular biology; Molecular biology; Molecular genetics; Mutagenesis. Repair; MutL Protein Homolog 1; MutS Homolog 3 Protein; NIH 3T3 Cells; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; PCNA; Proliferating Cell Nuclear Antigen - genetics; Proliferating Cell Nuclear Antigen - metabolism; Protein Transport - genetics; Protein Transport - radiation effects; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Recombinant Fusion Proteins - radiation effects; RecQ Helicases - genetics; RecQ Helicases - metabolism; Replication; Replication foci; S Phase; Werner Syndrome Helicase; Double strand break; PCNA; DNA mismatch repair; hEXO1; Replication foci; Human; Double stranded DNA; Replication; Repair; Protein; hEXO1PCNA
• ISSN: 1568-7864; 1568-7856
• DOI: 10.1016/j.dnarep.2010.09.023

Human exonuclease 1 (hEXO1) is implicated in DNA metabolism, including replication, recombination and repair, substantiated by its interactions with PCNA, DNA helicases BLM and WRN, and several DNA mismatch repair (MMR) proteins. We investigated the sub-nuclear localization of hEXO1 during S-phase progression and in response to laser-induced DNA double strand breaks (DSBs). We show that hEXO1 and PCNA co-localize in replication foci. This apparent interaction is sustained throughout S-phase. We also demonstrate that hEXO1 is rapidly recruited to DNA DSBs. We have identified a PCNA interacting protein (PIP-box) region on hEXO1 located in its COOH-terminal (
788QIKLNELW
795). This motif is essential for PCNA binding and co-localization during S-phase. Recruitment of hEXO1 to DNA DSB sites is dependent on the MMR protein hMLH1. We show that two distinct hMLH1 interaction regions of hEXO1 (residues 390–490 and 787–846) are required to direct the protein to the DNA damage site. Our results reveal that protein domains in hEXO1 in conjunction with specific protein interactions control bi-directional routing of hEXO1 between on-going DNA replication and repair processes in living cells.