Regucalcin increases Ca2+-ATPase activity in the mitochondria of brain tissues of normal and transgenic rats.
The role of regucalcin, which is a regulatory protein in intracellular signaling, in the regulation of Ca(2+)-ATPase activity in the mitochondria of brain tissues was investigated. The addition of regucalcin (10(-10) to 10(-8) M), which is a physiologic concentration in rat brain tissues, into the enzyme reaction mixture containing 25 microM calcium chloride caused a significant increase in Ca(2+)-ATPase activity, while it did not significantly change in Mg(2+)-ATPase activity. The effect of regucalcin (10(-9) M) in increasing mitochondrial Ca(2+)-ATPase activity was completely inhibited in the presence of ruthenium red (10(-7) M) or lanthanum chloride (10(-7) M), both of which are inhibitors of mitochondrial uniporter activity. Whether the effect of regucalcin is modulated in the presence of calmodulin or dibutyryl cyclic AMP (DcAMP) was examined. The effect of regucalcin (10(-9) M) in increasing Ca(2+)-ATPase activity was not significantly enhanced in the presence of calmodulin (2.5 microg/ml) which significantly increased the enzyme activity. DcAMP (10(-6) to 10(-4) M) did not have a significant effect on Ca(2+)-ATPase activity. The effect of regucalcin (10(-9) M) in increasing Ca(2+)-ATPase activity was not seen in the presence of DcAMP (10(-4) M). Regucalcin levels were significantly increased in the brain tissues or the mitochondria obtained from regucalcin transgenic (RC TG) rats. The mitochondrial Ca(2+)-ATPase activity was significantly increased in RC TG rats as compared with that of wild-type rats. This study demonstrates that regucalcin has a role in the regulation of Ca(2+)-ATPase activity in the brain mitochondria of rats.
Yamaguchi
Masayoshi
M
Laboratory of Endocrinology and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan. yamamasa1155@yahoo.co.jp
Takakura
Yusei
Y
Nakagawa
Taeko
T
D000818:Animals; D030801:Animals, Genetically Modified; D001921:Brain / Q000201:enzymology* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism*; D007811:Lanthanum / Q000494:pharmacology; D008099:Liver / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012430:Ruthenium Red / Q000494:pharmacology
D002135:Calcium-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C028521:lanthanum chloride; D012430:Ruthenium Red; D007811:Lanthanum; D002265:Carboxylic Ester Hydrolases; C513325:Rgn protein, rat; D000252:Calcium-Transporting ATPases; D002118:Calcium