Early-stage apoptosis is associated with DNA-damage-independent ATM phosphorylation and chromatin decondensation in NIH3T3 fibroblasts.

TY - JOUR

T1 - Early-stage apoptosis is associated with DNA-damage-independent ATM phosphorylation and chromatin decondensation in NIH3T3 fibroblasts.

AU - Schou, Kenneth Bødtker

AU - Schneider, Linda

AU - Christensen, Søren Tvorup

AU - Hoffmann, Else Kay

N1 - Keywords: Animals; Apoptosis; Caspase 3; Cell Cycle Proteins; Chromatin; Cycloheximide; DNA Damage; DNA Fragmentation; DNA-Binding Proteins; Enzyme Activation; Hypotonic Solutions; Mice; NIH 3T3 Cells; Phosphorylation; Protein-Serine-Threonine Kinases; Staurosporine; Tumor Necrosis Factor-alpha; Tumor Suppressor Proteins

PY - 2008

Y1 - 2008

N2 - Chromatin condensation and degradation of DNA into internucleosomal DNA fragments are key hallmarks of apoptosis. The phosphorylation of protein kinase ataxia telangiectasia mutated (ATM) and histone H2A.X was recently shown to occur concurrently with apoptotic DNA fragmentation. We have used immunofluorescence microscopy, Western blot analysis and alkali comet assays to show that phosphorylation of ATM in NIH3T3 fibroblasts occurs prior to apoptotic DNA fragmentation, nuclease degradation and phosphorylation of histone H2A.X in cells treated with low levels of either staurosporine (STS) or tumor necrosis factor-alpha mixed with cycloheximide (TNF-alpha/CHX). In extension to previous findings, ATM phosphorylation was associated with chromatin decondensation, i.e., by loss of dense foci of constitutive heterochromatin. These results suggest that chromatin is decondensed and that ATM is activated independently of DNA damage signaling pathways during the very early stages of apoptosis.

AB - Chromatin condensation and degradation of DNA into internucleosomal DNA fragments are key hallmarks of apoptosis. The phosphorylation of protein kinase ataxia telangiectasia mutated (ATM) and histone H2A.X was recently shown to occur concurrently with apoptotic DNA fragmentation. We have used immunofluorescence microscopy, Western blot analysis and alkali comet assays to show that phosphorylation of ATM in NIH3T3 fibroblasts occurs prior to apoptotic DNA fragmentation, nuclease degradation and phosphorylation of histone H2A.X in cells treated with low levels of either staurosporine (STS) or tumor necrosis factor-alpha mixed with cycloheximide (TNF-alpha/CHX). In extension to previous findings, ATM phosphorylation was associated with chromatin decondensation, i.e., by loss of dense foci of constitutive heterochromatin. These results suggest that chromatin is decondensed and that ATM is activated independently of DNA damage signaling pathways during the very early stages of apoptosis.

U2 - 10.1016/j.cellbi.2007.08.019

DO - 10.1016/j.cellbi.2007.08.019

M3 - Journal article

C2 - 17945518

SN - 1065-6995

VL - 32

SP - 107

EP - 113

JO - Cell Biology International

JF - Cell Biology International

IS - 1

ER -