CtIP links DNA double-strand break sensing to resection.
In response to DNA double-strand breaks (DSBs), cells sense the DNA lesions and then activate the protein kinase ATM. Subsequent DSB resection produces RPA-coated ssDNA that is essential for activation of the DNA damage checkpoint and DNA repair by homologous recombination (HR). However, the biochemical mechanism underlying the transition from DSB sensing to resection remains unclear. Using Xenopus egg extracts and human cells, we show that the tumor suppressor protein CtIP plays a critical role in this transition. We find that CtIP translocates to DSBs, a process dependent on the DSB sensor complex Mre11-Rad50-NBS1, the kinase activity of ATM, and a direct DNA-binding motif in CtIP, and then promotes DSB resection. Thus, CtIP facilitates the transition from DSB sensing to processing: it does so by binding to the DNA at DSBs after DSB sensing and ATM activation and then promoting DNA resection, leading to checkpoint activation and HR.
You
Zhongsheng
Z
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA. zyou@wustl.edu
Shi
Linda Z
LZ
Zhu
Quan
Q
Wu
Peng
P
Zhang
You-Wei
YW
Basilio
Andrew
A
Tonnu
Nina
N
Verma
Inder M
IM
Berns
Michael W
MW
Hunter
Tony
T
D000595:Amino Acid Sequence; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004706:Endodeoxyribonucleases; D004789:Enzyme Activation; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D016415:Sequence Alignment; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C112156:NBN protein, human; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D004706:Endodeoxyribonucleases; C410741:RBBP8 protein, human