Homodimerization of Nemo-like kinase is essential for activation and nuclear localization.
Nemo-like kinase (NLK) is an evolutionarily conserved protein kinase that phosphorylates several transcription factors. However, the molecular mechanisms that regulate NLK activity have been poorly understood. Here we show that homodimerization of NLK is required for its activation and nuclear localization. Biochemical analysis revealed that NLK is activated through intermolecular autophosphorylation of NLK dimers at Thr-286. Mutation of NLK at Cys-425, which corresponds to the defect in the Caenorhabditis elegans NLK homologue lit-1, prevented NLK dimerization, rendering NLK defective in both nuclear localization and kinase activity. By contrast, the external addition of nerve growth factor, which has been previously identified as an NLK activator, induced dimerization and Thr-286 autophosphorylation of endogenous NLK proteins. In addition, both dimerization and Thr-286 phosphorylation of NLK were found to be essential for induction of neurite-like cellular processes by NLK. The present findings suggest that dimerization is an initial key event required for the functional activation of NLK.
Division of Cell Regulation Systems, Department of Post-Genome Science Center, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan.
Shizuka
S
Ishitani
Kenji
K
Inaba
Kunihiro
K
Matsumoto
Tohru
T
Ishitani
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D003545:Cysteine / Q000235:genetics; D004789:Enzyme Activation; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D020932:Nerve Growth Factor / Q000494:pharmacology; D016501:Neurites / Q000378:metabolism; D016716:PC12 Cells; D010766:Phosphorylation; D055503:Protein Multimerization; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D051381:Rats; D016415:Sequence Alignment; D013912:Threonine / Q000378:metabolism
D047908:Intracellular Signaling Peptides and Proteins; D013912:Threonine; D020932:Nerve Growth Factor; C470551:NLK protein, human; D017346:Protein Serine-Threonine Kinases; D003545:Cysteine