Experimental design, validation and computational modeling uncover DNA damage sensing by DNA-PK and ATM.
Reliable and efficient detection of DNA damage constitutes a vital capability of human cells to maintain genome stability. Following DNA damage, the histone variant H2AX becomes rapidly phosphorylated by the DNA damage response kinases DNA-PKcs and ATM. H2AX phosphorylation plays a central role in signal amplification leading to chromatin remodeling and DNA repair initiation. The contribution of DNA-PKcs and ATM to H2AX phosphorylation is however puzzling. Although ATM is required, DNA-PKcs can substitute for it. Here we analyze the interplay between DNA-PKcs and ATM with a computational model derived by an iterative workflow: switching between experimental design, experiment and model analysis, we generated an extensive set of time-resolved data and identified a conclusive dynamic signaling model out of several alternatives. Our work shows that DNA-PKcs and ATM enforce a biphasic H2AX phosphorylation. DNA-PKcs can be associated to the initial, and ATM to the succeeding phosphorylation phase of H2AX resulting into a signal persistence detection function for reliable damage sensing. Further, our model predictions emphasize that DNA-PKcs inhibition significantly delays H2AX phosphorylation and associated DNA repair initiation.
Process Systems Engineering Group, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany. flassig@mpi-magdeburg.mpg.de.
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Flassig
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Maubach
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Täger
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Sundmacher
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Naumann
D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism*; D002867:Chromones / Q000494:pharmacology; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects; D051747:DNA-Activated Protein Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004285:Dogs; D006657:Histones / Q000378:metabolism*; D061985:Madin Darby Canine Kidney Cells; D008958:Models, Molecular; D009025:Morpholines / Q000494:pharmacology; D010766:Phosphorylation; D011753:Pyrones / Q000494:pharmacology; D011839:Radiation, Ionizing
C495818:2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one; C499693:8-dibenzothiophen-4-yl-2-morpholin-4-yl-chromen-4-one; D002867:Chromones; D006657:Histones; D009025:Morpholines; D011753:Pyrones; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase