Spreading of mammalian DNA-damage response factors studied by ChIP-chip at damaged telomeres.
Phosphorylated histone H2AX (gammaH2AX) is generated in nucleosomes flanking sites of DNA double-strand breaks, triggering the recruitment of DNA-damage response proteins such as MDC1 and 53BP1. Here, we study shortened telomeres in senescent human cells. We show that most telomeres trigger gammaH2AX formation, which spreads up to 570 kb into the subtelomeric regions. Furthermore, we reveal that the spreading patterns of 53BP1 and MDC1 are very similar to that of gammaH2AX, consistent with a structural link between these factors. Moreover, different subsets of telomeres signal in different cell lines, with those that signal tending to equate to the shortest telomeres of the corresponding cell line, thus linking telomere attrition with DNA-damage signalling. Notably, we find that, in some cases, gammaH2AX spreading is modulated in a manner suggesting that H2AX distribution or its ability to be phosphorylated is not uniform along the chromosome. Finally, we observe weak gammaH2AX signals at telomeres of proliferating cells, but not in hTERT immortalised cells, suggesting that low telomerase activity leads to telomere uncapping and senescence in proliferating primary cells.
Meier
Andreas
A
The Wellcome Trust and Cancer Research UK Gurdon Institute, Department of Zoology, University of Cambridge, Cambridge, UK.
Fiegler
Heike
H
Muñoz
Purificacion
P
Ellis
Peter
P
Rigler
Diane
D
Langford
Cordelia
C
Blasco
Maria A
MA
Carter
Nigel
N
Jackson
Stephen P
SP
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D002460:Cell Line; D016922:Cellular Senescence / Q000502:physiology; D047369:Chromatin Immunoprecipitation; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000235:genetics / Q000502:physiology*; D015534:Trans-Activators / Q000378:metabolism; D000071857:Tumor Suppressor p53-Binding Protein 1
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; D047908:Intracellular Signaling Peptides and Proteins; C413163:MDC1 protein, human; D009687:Nuclear Proteins; C498301:TP53BP1 protein, human; D015534:Trans-Activators; D000071857:Tumor Suppressor p53-Binding Protein 1; D019098:Telomerase