Morooka Yoshiko, Yamaguchi Masayoshi
Laboratory of Endocrinlogy and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
J Cell Biochem. 2002;85(3):553-60. doi: 10.1002/jcb.10157.
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.
内源调钙素（RC）作为一种钙信号调节蛋白，对氯化钙溶液（10毫克钙/100克体重）腹腔注射大鼠肾皮质细胞质和细胞核中蛋白磷酸酶活性（PPA）增强的抑制作用进行了研究。大鼠单次腹腔注射氯化钙溶液后0.5 - 5小时，肾皮质中的钙含量显著增加。用蛋白质免疫印迹法分析RC蛋白表明，注射钙（10毫克/100克）后0.5 - 5小时，细胞质和细胞核中的RC水平显著升高。在肾皮质的细胞质和细胞核中发现了针对磷酸酪氨酸、磷酸丝氨酸和磷酸苏氨酸的PPA。注射钙（10毫克/100克）后，细胞质和细胞核中针对三种磷酸氨基酸的PPA显著增加。在酶反应中加入抗RC单克隆抗体（25纳克/毫升），正常大鼠肾皮质细胞质和细胞核中针对磷酸酪氨酸、磷酸丝氨酸和磷酸苏氨酸的PPA显著增加。在注射钙的大鼠中，抗RC单克隆抗体（25纳克/毫升）增加细胞质和细胞核中针对三种磷酸氨基酸的PPA的作用显著增强。在酶反应混合物中加入RC（10⁻⁶摩尔），抗RC单克隆抗体（25纳克/毫升）增加正常大鼠和注射钙大鼠细胞质和细胞核中PPA的作用完全被消除。本研究表明，内源RC抑制注射钙大鼠肾皮质细胞质和细胞核中PPA的增强。
