title: Endogenous regucalcin suppresses the enhancement of protein phosphatase activity in the cytosol and nucleus of kidney cortex in calcium-administered rats.
abstract: The suppressive role of endogenous regucalcin (RC), which is a regulatory protein of calcium signaling, in the enhancement of protein phosphatase activity (PPA) in the cytosol and nucleus of kidney cortex in calcium-administered rats was investigated. Calcium content in the kidney cortex was significantly increased at 0.5-5 h after a single intraperitoneal administration of calcium chloride solution (10 mg Ca/100 g body weight) to rats. The analysis with Western blotting of RC protein showed that RC levels in the cytosol and nucleus were significantly increased 0.5-5 h after the administration of calcium (10 mg/100 g). PPA toward phosphotyrosine, phosphoserine, and phosphothreonine was found in the cytosol and nucleus of kidney cortex. PPA toward three phosphoamino acids in the cytosol and nucleus was significantly increased by the administration of calcium (10 mg/100 g). The presence of anti-RC monoclonal antibody (25 ng/ml) in the enzyme reaction caused a significant increase in PPA toward phosphotyrosine, phosphoserine, and phosphothreonine in the cytosol and nucleus of kidney cortex in normal rats. The effect of anti-RC monoclonal antibody (25 ng/ml) in increasing PPA toward three phosphoamino acids in the cytosol and nucleus was significantly enhanced in calcium-administered rats. The effect of anti-RC monoclonal antibody (25 ng/ml) in increasing PPA in the cytosol and nucleus of normal rats and calcium-administered rats was completely abolished by the addition of RC (10(- 6) M) in the enzyme reaction mixture. The present study suggests that endogenous RC suppresses the enhancement of PPA in the cytosol and nucleus of kidney cortex in calcium-administered rats.
authors.affiliation: Laboratory of Endocrinlogy and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Morooka
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000818:Animals; D002118:Calcium / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D002135:Calcium-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D047908:Intracellular Signaling Peptides and Proteins; D007672:Kidney Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015238:Sulfotransferases
chemical_list: D002135:Calcium-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D015238:Sulfotransferases; C028152:alcohol sulfotransferase; D002265:Carboxylic Ester Hydrolases; C513325:Rgn protein, rat; D010749:Phosphoprotein Phosphatases; D002118:Calcium