TY - JOUR

T1 - Human Xip1 (C2orf13) is a novel regulator of cellular responses to DNA strand breaks

AU - Bekker-Jensen, Simon

AU - Fugger, Kasper

AU - Danielsen, Jannie Rendtlew

AU - Gromova, Irina

AU - Sehested, Maxwell

AU - Celis, Julio

AU - Bartek, Jiri

AU - Lukas, Jiri

AU - Mailand, Niels

PY - 2007/7/6

Y1 - 2007/7/6

N2 - DNA strand breaks arise continuously as the result of intracellular metabolism and in response to a multitude of genotoxic agents. To overcome such challenges to genomic stability, cells have evolved genome surveillance pathways that detect and repair damaged DNA in a coordinated fashion. Here we identify the previously uncharacterized human protein Xip1 (C2orf13) as a novel component of the checkpoint response to DNA strand breaks. Green fluorescent protein-tagged Xip1 was rapidly recruited to sites of DNA breaks, and this accumulation was dependent on a novel type of zinc finger motif located in the C terminus of Xip1. The initial recruitment kinetics of Xip1 closely paralleled that of XRCC1, a central organizer of single strand break (SSB) repair, and its accumulation was both delayed and sustained when the detection of SSBs was abrogated by inhibition of PARP-1. Xip1 and XRCC1 stably interacted through recognition of CK2 phosphorylation sites in XRCC1 by the Forkhead-associated (FHA) domain of Xip1, and XRCC1 was required to maintain steady-state levels of Xip1. Moreover, Xip1 was phosphorylated on Ser-116 by ataxia telangiectasia-mutated in response to ionizing radiation, further underscoring the potential importance of Xip1 in the DNA damage response. Finally, depletion of Xip1 significantly decreased the clonogenic survival of cells exposed to DNA SSB- or double strand break-inducing agents. Collectively, these findings implicate Xip1 as a new regulator of genome maintenance pathways, which may function to organize DNA strand break repair complexes at sites of DNA damage.

AB - DNA strand breaks arise continuously as the result of intracellular metabolism and in response to a multitude of genotoxic agents. To overcome such challenges to genomic stability, cells have evolved genome surveillance pathways that detect and repair damaged DNA in a coordinated fashion. Here we identify the previously uncharacterized human protein Xip1 (C2orf13) as a novel component of the checkpoint response to DNA strand breaks. Green fluorescent protein-tagged Xip1 was rapidly recruited to sites of DNA breaks, and this accumulation was dependent on a novel type of zinc finger motif located in the C terminus of Xip1. The initial recruitment kinetics of Xip1 closely paralleled that of XRCC1, a central organizer of single strand break (SSB) repair, and its accumulation was both delayed and sustained when the detection of SSBs was abrogated by inhibition of PARP-1. Xip1 and XRCC1 stably interacted through recognition of CK2 phosphorylation sites in XRCC1 by the Forkhead-associated (FHA) domain of Xip1, and XRCC1 was required to maintain steady-state levels of Xip1. Moreover, Xip1 was phosphorylated on Ser-116 by ataxia telangiectasia-mutated in response to ionizing radiation, further underscoring the potential importance of Xip1 in the DNA damage response. Finally, depletion of Xip1 significantly decreased the clonogenic survival of cells exposed to DNA SSB- or double strand break-inducing agents. Collectively, these findings implicate Xip1 as a new regulator of genome maintenance pathways, which may function to organize DNA strand break repair complexes at sites of DNA damage.

KW - Cell Cycle Proteins

KW - Cell Line, Tumor

KW - DNA Breaks, Double-Stranded

KW - DNA Breaks, Single-Stranded

KW - DNA Repair

KW - DNA-Binding Proteins

KW - Genomic Instability

KW - Humans

KW - Phosphoproteins

KW - Phosphorylation

KW - Protein Processing, Post-Translational

KW - Protein Structure, Tertiary

KW - Protein-Serine-Threonine Kinases

KW - Zinc Fingers

U2 - 10.1074/jbc.C700060200

DO - 10.1074/jbc.C700060200

M3 - Journal article

C2 - 17507382

VL - 282

SP - 19638

EP - 19643

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 27

ER -