title: Inhibitory role of regucalcin in the regulation of Ca2+ dependent protein kinases activity in rat brain neurons.
abstract: The role of regucalcin in the regulation of protein kinase activity in rat brain neuronal cells obtained from primary culture was investigated. Protein kinase activity was assayed using the 5500 g supernatant fraction of the cell homogenate. Protein kinase activity was significantly raised by the addition of calmodulin (5 microg/ml) or dioctanoylglycerol (5 microg/ml) in the presence of CaCl2 (10(-4) M), indicating that Ca2+/calmodulin-dependent protein kinase and protein kinase C is present in the neuronal cells. The addition of regucalcin (10(-9)-10(-7) M) in the enzyme reaction mixture caused a significant decrease in protein kinase activity in the absence of calmodulin or dioctanoylglycerol without Ca(2+) addition. Moreover, regucalcin completely prevented the activation of protein kinase by the addition of calmodulin or dioctonoylglyceral in the presence of CaCl(2) (10(-4) M). The presence of anti-regucalcin monoclonal antibody (25 or 50 ng/ml) caused a significant elevation of protein kinase activity without CaCl2 addition. Such an effect was significantly inhibited by the addition of trifluoperazine (2x10(-5) M), an antagonist of calmodulin, or staurosporine (10(-6) M), an inhibitor of protein kinase C. The present study demonstrates that endogenous regucalcin in rat brain neuronal cells has an inhibitory effect on Ca2+ dependent protein kinase activity.
authors.affiliation: Laboratory of Endocrinology and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, 52-1 Yada, 422-8526, Shizuoka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hamano
authors.forename: M
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D002265:Carboxylic Ester Hydrolases; D002478:Cells, Cultured; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D009474:Neurons / Q000187:drug effects* / Q000201:enzymology; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D015238:Sulfotransferases; D017871:Calcium-Calmodulin-Dependent Protein Kinases
chemical_list: D000911:Antibodies, Monoclonal; D002135:Calcium-Binding Proteins; D002265:Carboxylic Ester Hydrolases; D047908:Intracellular Signaling Peptides and Proteins; D011494:Protein Kinases; D015238:Sulfotransferases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C513324:Rgn protein, mouse; C028152:alcohol sulfotransferase; C513325:Rgn protein, rat