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Role of calcium‐binding protein regucalcin in regenerating rat liver
Author(s) -
YAMAGUCHI MASAYOSHI
Publication year - 1998
Publication title -
journal of gastroenterology and hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.214
H-Index - 130
eISSN - 1440-1746
pISSN - 0815-9319
DOI - 10.1111/jgh.1998.13.s1.106
Subject(s) - calcium binding protein , biology , calmodulin , messenger rna , endocrinology , microbiology and biotechnology , medicine , gene expression , calcium , gene , biochemistry
Regucalcin is a novel calcium‐binding protein which does not contain EF‐hand motif as a Ca 2+ ‐binding domain. The organization of the rat regucalcin gene consists of seven exons and six introns. Its mRNA is mainly present in liver but slightly in kidney with a size of 1.8 kb. Hepatic regucalcin mRNA expression is stimulated by various factors including calcium, calcitonin, insulin, and oestrogen in rats. The mRNA is also expressed in hepatoma cells (Morris hepatoma and HepG2). Regucalcin plays a role in the maintenance of cytosolic Ca 2+ homeostasis in liver cells. Moreover, regucalcin has an inhibitory effect on Ca 2+ /calmodulin‐dependent enzyme activation, protein kinase C activation, and many Ca 2+ ‐activated enzymes, indicating a role in the regulation of the Ca 2+ ‐signalling system. Recently, regucalcin has been demonstrated to regulate nuclear function in liver cells. Regucalcin can inhibit Ca 2+ ‐activated nuclear DNA fragmentation in rat isolated liver nuclei. Furthermore, the liver nuclear DNA and RNA syntheses are inhibited by regucalcin. Such an effect of regucalcin is also seen in the nuclei of regenerating rat liver. The regucalcin mRNA level is increased in regenerating liver. These findings suggest that regucalcin plays a regulatory role in the suppression for overexpression of proliferative cells.