DNA-SCARS: distinct nuclear structures that sustain damage-induced senescence growth arrest and inflammatory cytokine secretion.
DNA damage can induce a tumor suppressive response termed cellular senescence. Damaged senescent cells permanently arrest growth, secrete inflammatory cytokines and other proteins and harbor persistent nuclear foci that contain DNA damage response (DDR) proteins. To understand how persistent damage foci differ from transient foci that mark repairable DNA lesions, we identify sequential events that differentiate transient foci from persistent foci, which we term 'DNA segments with chromatin alterations reinforcing senescence' (DNA-SCARS). Unlike transient foci, DNA-SCARS associate with PML nuclear bodies, lack the DNA repair proteins RPA and RAD51, lack single-stranded DNA and DNA synthesis and accumulate activated forms of the DDR mediators CHK2 and p53. DNA-SCARS form independently of p53, pRB and several other checkpoint and repair proteins but require p53 and pRb to trigger the senescence growth arrest. Importantly, depletion of the DNA-SCARS-stabilizing component histone H2AX did not deplete 53BP1 from DNA-SCARS but diminished the presence of MDC1 and activated CHK2. Furthermore, depletion of H2AX reduced both the p53-dependent senescence growth arrest and p53-independent cytokine secretion. DNA-SCARS were also observed following severe damage to multiple human cell types and mouse tissues, suggesting that they can be used in combination with other markers to identify senescent cells. Thus, DNA-SCARS are dynamically formed distinct structures that functionally regulate multiple aspects of the senescent phenotype.
Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA.
Francis
F
Rodier
Denise P
DP
Muñoz
Robert
R
Teachenor
Victoria
V
Chu
Oanh
O
Le
Dipa
D
Bhaumik
Jean-Philippe
JP
Coppé
Eric
E
Campeau
Christian M
CM
Beauséjour
Sahn-Ho
SH
Kim
Albert R
AR
Davalos
Judith
J
Campisi
D000818:Animals; D002453:Cell Cycle / Q000528:radiation effects*; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D016922:Cellular Senescence / Q000528:radiation effects*; D002843:Chromatin / Q000235:genetics / Q000378:metabolism*; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage / Q000528:radiation effects*; D006657:Histones / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D000071156:Promyelocytic Leukemia Protein; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D014965:X-Rays
D002843:Chromatin; D016207:Cytokines; D006657:Histones; D009687:Nuclear Proteins; D000071156:Promyelocytic Leukemia Protein; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human