title: Phosphorylation and activation of nuclear Ca2+/calmodulin-dependent protein kinase phosphatase (CaMKP-N/PPM1E) by Ca2+/calmodulin-dependent protein kinase I (CaMKI).
abstract: Nuclear Ca(2+)/calmodulin-dependent protein kinase phosphatase (CaMKP-N/PPM1E) is an enzyme that dephosphorylates and downregulates multifunctional Ca(2+)/calmodulin-dependent protein kinases (CaMKs) as well as AMP-dependent protein kinase. In our previous study, we found that zebrafish CaMKP-N (zCaMKP-N) underwent proteolytic processing and translocated to cytosol in a proteasome inhibitor-sensitive manner. In the present study, we found that zCaMKP-N is regulated by phosphorylation at Ser-480. When zCaMKP-N was incubated with the activated CaMKI, time-dependent phosphorylation of the enzyme was observed. This phosphorylation was significantly reduced when Ser-480 was replaced by Ala, suggesting that CaMKI phosphorylates Ser-480 of zCaMKP-N. Phosphorylation-mimic mutants, S480D and S480E, showed higher phosphatase activities than those of wild type and S480A mutant in solution-based phosphatase assay using various substrates. Furthermore, autophosphorylation of CaMKII after ionomycin treatment was more severely attenuated in Neuro2a cells when CaMKII was cotransfected with the phosphorylation-mimic mutant of zCaMKP-N than with the wild-type or non-phosphorylatable zCaMKP-N. These results strongly suggest that phosphorylation of zCaMKP-N at Ser-480 by CaMKI activates CaMKP-N catalytic activity and thereby downregulates multifunctional CaMKs in the cytosol.
authors.affiliation: Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa 761-0795, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Onouchi
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Sueyoshi
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Ishida
authors.forename: Isamu
authors.initials: I
authors.lastname: Kameshita
mesh_terms: D000409:Alanine / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1 / Q000378:metabolism*; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D000071636:Protein Phosphatase 2C; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000235:genetics / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D012694:Serine; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D010749:Phosphoprotein Phosphatases; C000607482:Ppm1e protein, rat; D000071636:Protein Phosphatase 2C; D000409:Alanine