Ca(2+)/Calmodulin-dependent protein kinase cascade in Caenorhabditis elegans. Implication in transcriptional activation.
We have recently demonstrated that Caenorhabditis elegans Ca(2+)/calmodulin-dependent protein kinase kinase (CeCaM-KK) can activate mammalian CaM-kinase IV in vitro (Tokumitsu, H., Takahashi, N., Eto, K., Yano, S., Soderling, T.R., and Muramatsu, M. (1999) J. Biol. Chem. 274, 15803-15810). In the present study, we have identified and cloned a target CaM-kinase for CaM-KK in C. elegans, CeCaM-kinase I (CeCaM-KI), which has approximately 60% identity to mammalian CaM-KI. CeCaM-KI has 348 amino acid residues with an apparent molecular mass of 40 kDa, which is activated by CeCaM-KK through phosphorylation of Thr(179) in a Ca(2+)/CaM-dependent manner, resulting in a 30-fold decrease in the K(m) of CeCaM-KI for its peptide substrate. Unlike mammalian CaM-KI, CeCaM-KI is mainly localized in the nucleus of transfected cells because the NH(2)-terminal six residues ((2)PLFKRR(7)) contain a functional nuclear localization signal. We have also demonstrated that CeCaM-KK and CeCaM-KI reconstituted a signaling pathway that mediates Ca(2+)-dependent phosphorylation of cAMP response element-binding protein (CREB) and CRE-dependent transcriptional activation in transfected cells, consistent with nuclear localization of CeCaM-KI. These results suggest that the CaM-KK/CaM-KI cascade is conserved in C. elegans and is functionally operated both in vitro and in intact cells, and it may be involved in Ca(2+)-dependent nuclear events such as transcriptional activation through phosphorylation of CREB.
Eto
K
K
Helix Research Institute, Inc., 1532-3 Yana, Kisarazu-shi, Chiba 292-0812, Japan.
Takahashi
N
N
Kimura
Y
Y
Masuho
Y
Y
Arai
K
K
Muramatsu
M A
MA
Tokumitsu
H
H
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000201:enzymology / Q000235:genetics*; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000201:enzymology; D003001:Cloning, Molecular; D004789:Enzyme Activation; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013045:Species Specificity; D015533:Transcriptional Activation
D017346:Protein Serine-Threonine Kinases; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D017871:Calcium-Calmodulin-Dependent Protein Kinases