Human TAO kinase 1 induces apoptosis in SH-SY5Y cells.
The human TAO kinase 1 (hTAOK1) is a member of the Ste20 group of kinases with the kinase domain located at the N-terminus. The rat homologue, originally named TAO1, has been demonstrated to be highly expressed in brain. In this study, the human TAO kinase 1 was transfected into human neuroblastoma SH-SY5Y cells and its biological effects on the cell morphology were observed by co-expressing the enhanced green fluorescent protein (EGFP). It was found that after 16 h of transfection the cells had shrunk, and finally became rounded when transfected with wild-type or mutant K57A genes encoding either the kinase domain (residues 1-376) or the full-length molecule (residues 1-1001). Thirty-four hours after transfection, cells floated and apoptotic bodies were observed after nuclear staining with DAPI. On the other hand, the cells that were transfected with the gene encoding the C-terminal regulatory region (residues 377-1001) of hTAOK1, appeared to remain unchanged. In order to know the signaling events involved in the above biological phenomena, caspase-3-like activities of the transfected cells were measured in the absence or presence of JNK inhibitor SP600125, in which caspase-3 and JNK (C-jun-N-terminal kinase) are both known to be critical components of the neuronal apoptosis. The results showed that the apoptotic cells exhibited elevated caspase-3-like activity, which could be reduced by SP600125 to some extent. It is concluded that human TAO kinase 1 induces apoptosis in SH-SY5Y cells and the kinase domain is essential, but its catalytic activity seems to be dispensable in this case.
Wu
Ming-Fang
MF
Central Taiwan University of Science and Technology, Department of Medical Laboratory Science and Biotechnology, Taichung 406, Taiwan.
Wang
Shyang-Guang
SG
D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D014162:Transfection
D000873:Anthracenes; C432165:pyrazolanthrone; D017346:Protein Serine-Threonine Kinases; C115483:TAO1 protein kinase; D048031:JNK Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D053148:Caspase 3