Expression of a constitutive form of calcium/calmodulin dependent protein kinase II leads to arrest of the cell cycle in G2.
Calcium/calmodulin dependent protein kinase II (CaMKII) is a multifunctional serine/threonine protein kinase. We have created a calcium/calmodulin independent form of this enzyme by truncation. Expression of this enzyme fragment in a rabbit reticulocyte lysate yields a constitutive enzyme with specific activity similar to the activated native enzyme. We have established mammalian cell lines that transiently express this constitutive enzyme using the glucocorticoid-inducible mouse mammary tumor virus long terminal repeat. The transient increase in kinase activity results in a complete cessation of cell cycle progression. This block develops as a consequence of a specific arrest of the cell cycle in G2. During the block, increases in histone H1 kinase activity present in p13 beads or anti-cdc2 immunoprecipitates are seen in parallel with the accumulation of cells at G2, arguing that the arrest is not due to a failure to activate cdc2 as a histone H1 kinase. These results suggest that other changes in serine/threonine protein phosphorylation besides those involved in activation of cdc2 as a histone H1 kinase may be necessary for proper G2-M transition.
Planas-Silva
M D
MD
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030.
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D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000201:enzymology; D016203:CDC2 Protein Kinase / Q000032:analysis / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D002872:Chromosome Deletion; D016213:Cyclins / Q000032:analysis / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D005822:Genetic Vectors; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D010957:Plasmids; D006656:Protamine Kinase / Q000032:analysis / Q000378:metabolism; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
D016213:Cyclins; D012313:RNA; D003907:Dexamethasone; D011494:Protein Kinases; D006656:Protamine Kinase; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D016203:CDC2 Protein Kinase