Study of the cytolethal distending toxin (CDT)-activated cell cycle checkpoint. Involvement of the CHK2 kinase.
The bacterial cytolethal distending toxin (CDT) triggers a G2/M cell cycle arrest in eukaryotic cells by inhibiting the CDC25C phosphatase-dependent CDK1 dephosphorylation and activation. We report that upon CDT treatment CDC25C is fully sequestered in the cytoplasmic compartment, an effect that is reminiscent of DNA damage-dependent checkpoint activation. We show that the checkpoint kinase CHK2, an upstream regulator of CDC25C, is phosphorylated and activated after CDT treatment. In contrast to what is observed with other DNA damaging agents, we demonstrate that the activation of CHK2 can only take place during S-phase. Use of wortmannin and caffeine suggests that this effect is not dependent on ATM but rather on another as yet unidentified PI3 kinase family member. These results confirm that the CDT is therefore responsible for specific genomic injuries that block cell proliferation by activating a cell cycle checkpoint.
LBCMCP UMR5088, Université Paul Sabatier, CNRS, Toulouse, France.
F
F
Alby
R
R
Mazars
J
J
de Rycke
E
E
Guillou
V
V
Baldin
J M
JM
Darbon
B
B
Ducommun
D000730:Androstadienes / Q000494:pharmacology; D064007:Ataxia Telangiectasia Mutated Proteins; D001427:Bacterial Toxins / Q000494:pharmacology*; D002110:Caffeine / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D004268:DNA-Binding Proteins; D016195:G2 Phase / Q000187:drug effects / Q000502:physiology; D018816:Genes, cdc / Q000187:drug effects*; D006367:HeLa Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src); D016196:S Phase / Q000187:drug effects / Q000502:physiology; D025521:Tumor Suppressor Proteins; D000077191:Wortmannin; D020687:cdc25 Phosphatases / Q000378:metabolism
D000730:Androstadienes; D001427:Bacterial Toxins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D025521:Tumor Suppressor Proteins; C067044:cytolethal distending toxin; D002110:Caffeine; D011505:Protein-Tyrosine Kinases; C085377:MATK protein, human; D016392:Proto-Oncogene Proteins pp60(c-src); C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; C517009:CDC25C protein, human; D020687:cdc25 Phosphatases; D000077191:Wortmannin