title: DNA damage to a single chromosome end delays anaphase onset.
abstract: Chromosome ends contain nucleoprotein structures known as telomeres. Damage to chromosome ends during interphase elicits a DNA damage response (DDR) resulting in cell cycle arrest. However, little is known regarding the signaling from damaged chromosome ends (designated here as "TIPs") during mitosis. In the present study, we investigated the consequences of DNA damage induced at a single TIP in mitosis. We used laser microirradiation to damage mitotic TIPs or chromosome arms (non-TIPs) in PtK2 kidney epithelial cells. We found that damage to a single TIP, but not a non-TIP, delays anaphase onset. This TIP-specific checkpoint response is accompanied by differential recruitment of DDR proteins. Although phosphorylation of H2AX and the recruitment of several repair factors, such as Ku70-Ku80, occur in a comparable manner at both TIP and non-TIP damage sites, DDR factors such as ataxia telangiectasia mutated (ATM), MDC1, WRN, and FANCD2 are specifically recruited to TIPs but not to non-TIPs. In addition, Nbs1, BRCA1, and ubiquitin accumulate at damaged TIPs more rapidly than at damaged non-TIPs. ATR and 53BP1 are not detected at either TIPs or non-TIPs in mitosis. The observed delay in anaphase onset is dependent on the activity of DDR kinases ATM and Chk1, and the spindle assembly checkpoint kinase Mps1. Cells damaged at a single TIP or non-TIP eventually exit mitosis with unrepaired lesions. Damaged TIPs are segregated into micronuclei at a significantly higher frequency than damaged non-TIPs. Together, these findings reveal a mitosis-specific DDR uniquely associated with chromosome ends.
authors: Beckman Laser Institute and Medical Clinic, Irvine, California 92612,; Department of Developmental and Cell Biology, School of Biological Sciences, University of California, Irvine, California 92617.
authors: Bárbara Alcaraz
authors: BA
authors: Silva
authors: Beckman Laser Institute and Medical Clinic, Irvine, California 92612.
authors: Jessica R
authors: JR
authors: Stambaugh
authors: Department of Biological Chemistry, School of Medicine, University of California, Irvine, California 92697-1700, and. Electronic address: kyokomor@uci.edu.
authors: Kyoko
authors: K
authors: Yokomori
authors: Department of Systems Biology, Harvard Medical School and Renal Division, Brigham and Women's Hospital, Boston, Massachusetts 02115. Electronic address: jagesh@hms.harvard.edu.
authors: Jagesh V
authors: JV
authors: Shah
authors: Beckman Laser Institute and Medical Clinic, Irvine, California 92612,; Department of Developmental and Cell Biology, School of Biological Sciences, University of California, Irvine, California 92617,; Department of Biomedical Engineering, University of California, Irvine, California 92617,. Electronic address: mwberns@uci.edu.
authors: Michael W
authors: MW
authors: Berns
mesh_terms: D000705:Anaphase; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D002460:Cell Line; D000071877:Checkpoint Kinase 1; D033481:Chromosomes, Mammalian / Q000378:metabolism*; D004249:DNA Damage; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000378:metabolism; D052236:Fanconi Anemia Complementation Group D2 Protein / Q000378:metabolism; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D007834:Lasers / Q000009:adverse effects*; D010766:Phosphorylation; D048328:Potoroidae; D011494:Protein Kinases / Q000378:metabolism
chemical_list: D052236:Fanconi Anemia Complementation Group D2 Protein; D006657:Histones; D011494:Protein Kinases; D051418:Focal Adhesion Kinase 2; D064007:Ataxia Telangiectasia Mutated Proteins; D000071877:Checkpoint Kinase 1; D005090:Exodeoxyribonucleases
keywords: Anaphase; Chromosomes; Cytokinesis; DNA Damage; DNA Damage Response; Laser Microirradiation; Mitosis