Human TAO kinase 1 induces apoptosis in SH-SY5Y cells

Authors

  • Ming-Fang Wu,

    1. Central Taiwan University of Science and Technology, Department of Medical Laboratory Science and Biotechnology, Taichung 406, Taiwan
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  • Shyang-Guang Wang

    Corresponding author
    1. Central Taiwan University of Science and Technology, Department of Medical Laboratory Science and Biotechnology, Taichung 406, Taiwan
      Corresponding author at: No.11 Pu-tzu Lane, Pei-tun District, Taichung 406, Taiwan. Tel.: +886 4 2239 1647x6917; fax: +886 4 2239 5474. sgwang@ctust.edu.tw
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Corresponding author at: No.11 Pu-tzu Lane, Pei-tun District, Taichung 406, Taiwan. Tel.: +886 4 2239 1647x6917; fax: +886 4 2239 5474. sgwang@ctust.edu.tw

Abstract

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.

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