Inhibition of G2/M progression in Schizosaccharomyces pombe by a mutant calmodulin kinase II with constitutive activity.
Intracellular signaling by the second messenger Ca2+ through its receptor calmodulin (CaM) regulates cell function via the activation of CaM-dependent enzymes. Previous studies have shown that cell cycle progression at G1/S and G2/M is sensitive to intracellular CaM levels. However, little is known about the CaM-regulated enzymes involved. Protein phosphorylation has been shown to be important for cell-cycle regulation. Because CaM regulates several protein kinases, and at least one protein phosphatase, our studies are focusing on the roles of these enzymes within the cell cycle. As an initial approach to this problem, cDNAs encoding either normal or mutant calcium/calmodulin kinase II (CaMKII) have been expressed in Schizosaccharomyces pombe. The results show that overexpression of a constitutively active mutant CaMKII caused cell-cycle arrest in G2. Arrest was associated with a failure to activate the p34/cdc2 protein kinase. Expression of the mutant CaMKII in strains of S. pombe with altered timing of mitosis revealed that this effect is not mediated either by cdc25+ or wee1+, suggesting that CaMKII may regulate G2/M progression by another mechanism.
Rasmussen
C
C
Department of Anatomy and Cell Biology, University of Alberta, Edmonton, Canada.
Rasmussen
G
G
D000818:Animals; D001483:Base Sequence; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002118:Calcium / Q000502:physiology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics* / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D018797:Cell Cycle Proteins; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000378:metabolism; D007399:Interphase; D008677:Metaphase; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D000072380:NIMA-Related Kinase 1; D000072379:NIMA-Related Kinases; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012568:Schizosaccharomyces / Q000502:physiology*; D015398:Signal Transduction
D002147:Calmodulin; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D000072380:NIMA-Related Kinase 1; D000072379:NIMA-Related Kinases; C442331:NIMA-related kinase 6; C000606920:Nek1 protein, mouse; D017346:Protein Serine-Threonine Kinases; C000606921:fin1 protein, S pombe; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D016203:CDC2 Protein Kinase; D002118:Calcium