Nuclear localization signal and phosphorylation of Serine350 specify intracellular localization of DRAK2.
DAP kinase-related apoptosis-inducing kinase 2 (DRAK2) is a serine/threonine kinase of the death-associated protein kinase family. DRAK2 mediates apoptosis induced by extracellular stimuli, including UV irradiation and interleukin-2, and also regulates T-cell receptor sensitivity in developing thymocytes. During these events, the subcellular localization of DRAK2 changes between the nucleus and cytoplasm. We found that DRAK2 has a putative nuclear-localization signal (NLS) sequence. Mutations in this sequence interfered with DRAK2 localization to the nucleus. Furthermore, green fluorescence protein fused to the putative NLS accumulated in the nucleus, indicating that the putative sequence functions as an NLS. We also found that the function of the NLS was regulated by phosphorylation. Phorbol myristate acetate (PMA) induced the accumulation of DRAK2 in the cytoplasm of NIH3T3 cells, whereas in the absence of PMA, DRAK2 was localized to the nucleus. Ectopic expression of PKC-gamma induced cytoplasmic localization of DRAK2 and PKC-gamma phosphorylated Ser350 flanking the NLS. DRAK2, but not the Ser350Asp mutant, accumulated in the nuclei of ACL-15 cells in response to UV-irradiation. These results suggest that phosphorylation of Ser350 plays an essential role in regulating translocation of DRAK2 to the nucleus from the cytoplasm, possibly by affecting the activity of the NLS.
Kuwahara
Hiroshi
H
Department of Biological Sciences, Graduate School of Science, Osaka University, Machikaneyama-cho, Toyonaka City, Osaka, Japan.
Nishizaki
Michihiko
M
Kanazawa
Hiroshi
H
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D002522:Chlorocebus aethiops; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D019913:Nuclear Localization Signals / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D010768:Phosphoserine / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects / Q000528:radiation effects; D051381:Rats; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014466:Ultraviolet Rays
D019913:Nuclear Localization Signals; D010768:Phosphoserine; C441463:Stk17b protein, rat; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate