Prominent expression and activity-dependent nuclear translocation of Ca2+/calmodulin-dependent protein kinase Idelta in hippocampal neurons.
Multifunctional Ca2+/calmodulin-dependent protein kinases (CaMKs) including CaMKI, II and IV, are thought to regulate a variety of neuronal functions. Unlike CaMKII, which is regulated by autophosphorylation, CaMKI as well as CaMKIV are activated by CaMKK. In this study, we examined the cellular and subcellular localization of CaMKIdelta, a recently identified fourth isoform of CaMKI, in the mature brain. In situ hybridization analysis demonstrated wide expression of CaMKIdelta mRNA in the adult mouse brain with prominent expression in the hippocampal pyramidal cells. FLAG-tagged CaMKIdelta was localized at the cytoplasm and neurites without nuclear immunoreactivity in approximately 80% of the transfected primary hippocampal neurons. The stimulation with either KCl depolarization or glutamate triggered the nuclear localization of FLAG-tagged CaMKIdelta by two-fold with a peak at 1 min. In contrast, the catalytically inactive mutants of CaMKIdelta remained cytoplasmic without nuclear translocation during KCl depolarization, indicating the requirement of its activation for the nuclear translocation. Furthermore, we showed that immunoprecipitated CaMKIdelta could phosphorylate cAMP response element binding protein (CREB)alphain vitro and that the over-expression of CaMKIdelta enhanced GAL4-CREB-luciferase activity in PC12 cells stimulated by KCl depolarization. Our present study provides the first evidence for the possible involvement of CaMKIdelta in nuclear functions through its nuclear translocation in response to stimuli that trigger intracellular Ca2+ influx.
Sakagami
Hiroyuki
H
Division of Histology, Department of Cell Biology, Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan. hsakagam@gonryo.med.tohoku.ac.jp
Kamata
Akifumi
A
Nishimura
Hideki
H
Kasahara
Jiro
J
Owada
Yuji
Y
Takeuchi
Yusuke
Y
Watanabe
Makoto
M
Fukunaga
Kohji
K
Kondo
Hisatake
H
D000818:Animals; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D005822:Genetic Vectors; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000201:enzymology*; D017403:In Situ Hybridization; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000201:enzymology*; D010766:Phosphorylation; D011189:Potassium Chloride / Q000494:pharmacology; D011247:Pregnancy; D021381:Protein Transport / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection
D017362:Cyclic AMP Response Element-Binding Protein; D018076:DNA, Complementary; D018698:Glutamic Acid; D011189:Potassium Chloride; D008156:Luciferases; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517598:Camk1 protein, mouse; C517599:Camk1 protein, rat; C517681:Pnck protein, mouse; C517682:Pnck protein, rat