Apoptotic signaling in response to a single type of DNA lesion, O(6)-methylguanine.
Until now, it has been difficult to establish exactly how a specific DNA lesion signals apoptosis because each DNA damaging agent produces a collection of distinct DNA lesions and produces damage in RNA, protein, and lipids. We have developed a system in human cells that focuses on the response to a single type of DNA lesion, namely O(6)-methylguanine (O(6)MeG). We dissect the signaling pathways involved in O(6)MeG-induced apoptosis, a response dependent on the MutSalpha heterodimer that is normally involved in DNA mismatch repair. O(6)MeG triggers robust activation of caspases associated with both death receptor- and mitochondrial-mediated apoptosis. Despite this, O(6)MeG/MutSalpha-triggered apoptosis is only partly dependent on caspase activation; moreover, it is mediated solely by mitochondrial signaling and not at all by death receptor signaling. Finally, while Bcl-2 and Bcl-x(L), negative regulators of mitochondrial-regulated apoptosis, could effectively block O(6)MeG/MutSalpha-dependent apoptosis, they were unable to prevent the cells from ultimately dying.
Hickman
Mark J
MJ
Department of Biological Engineering and Center for Environmental Health Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Samson
Leona D
LD
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D020137:Base Pair Mismatch; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D053222:Fas Ligand Protein; D044943:Fatty Acid Desaturases / Q000378:metabolism; D006151:Guanosine / Q000031:analogs & derivatives* / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D008769:Methylnitronitrosoguanidine / Q000378:metabolism; D051719:MutS DNA Mismatch-Binding Protein; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051020:bcl-X Protein; D019014:fas Receptor / Q000378:metabolism
D029681:Arabidopsis Proteins; C494811:BCL2L1 protein, human; D001426:Bacterial Proteins; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D004268:DNA-Binding Proteins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; D051020:bcl-X Protein; D019014:fas Receptor; D006151:Guanosine; D008769:Methylnitronitrosoguanidine; C046175:6'-O-methylguanosine; D044943:Fatty Acid Desaturases; C084083:Fad7 protein, Arabidopsis; D020169:Caspases; D000251:Adenosine Triphosphatases; D051719:MutS DNA Mismatch-Binding Protein