TTK/hMps1 participates in the regulation of DNA damage checkpoint response by phosphorylating CHK2 on threonine 68.
CHK2/hCds1 plays important roles in the DNA damage-induced cell cycle checkpoint by phosphorylating several important targets, such as Cdc25 and p53. To obtain a better understanding of the CHK2 signaling pathway, we have carried out a yeast two-hybrid screen to search for potential CHK2-interacting proteins. Here, we report the identification of the mitotic checkpoint kinase, TTK/hMps1, as a novel CHK2-interacting protein. TTK/hMps1 directly phosphorylates CHK2 on Thr-68 in vitro. Expression of a TTK kinase-dead mutant, TTK(D647A), interferes with the G(2)/M arrest induced by either ionizing radiation or UV light. Interestingly, induction of CHK2 Thr-68 phosphorylation and of several downstream events, such as cyclin B1 accumulation and Cdc2 Tyr-15 phosphorylation, is also affected. Furthermore, ablation of TTK expression using small interfering RNA results not only in reduced CHK2 Thr-68 phosphorylation, but also in impaired growth arrest. Our results are consistent with a model in which TTK functions upstream from CHK2 in response to DNA damage and suggest possible cross-talk between the spindle assembly checkpoint and the DNA damage checkpoint.
Wei
Jen-Hsuan
JH
Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.
Chou
Yi-Fan
YF
Ou
Yi-Hung
YH
Yeh
Yen-Hsiu
YH
Tyan
Shiaw-Wei
SW
Sun
Te-Ping
TP
Shen
Chen-Yang
CY
Shieh
Sheau-Yann
SY
D015153:Blotting, Western; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism* / Q000502:physiology*; D002455:Cell Division; D002460:Cell Line; D045744:Cell Line, Tumor; D064447:Checkpoint Kinase 2; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D004249:DNA Damage; D004926:Escherichia coli / Q000378:metabolism; D016195:G2 Phase; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D008954:Models, Biological; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism* / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D011505:Protein-Tyrosine Kinases; D034741:RNA, Small Interfering / Q000378:metabolism; D011839:Radiation, Ionizing; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D013912:Threonine / Q000737:chemistry*; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D014443:Tyrosine / Q000737:chemistry; D014466:Ultraviolet Rays
C534699:CCNB1 protein, human; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; D013912:Threonine; D014443:Tyrosine; D005982:Glutathione Transferase; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; D011505:Protein-Tyrosine Kinases; C578634:CHEK2 protein, human; D017346:Protein Serine-Threonine Kinases; C075840:TTK protein, human