Ishibashi K, Miyamoto K, Taketani Y, Morita K, Takeda E, Sasaki S, Imai M
Department of Pharmacology, Jichi Medical School, Tochigi, Japan.
Biochem Biophys Res Commun. 1998 Sep 18;250(2):252-8. doi: 10.1006/bbrc.1998.9300.
Stanniocalcin (STC) is a Ca- and phosphate-regulating hormone produced by the corpuscles of Stannius in bony fishes. The mammalian homologue of STC has recently been reported (STC1), which stimulates the phosphate uptake of kidney. Here we report the cloning of a second mammalian stanniocalcin (STC2) from the human osteosarcoma cDNA library. STC2 has 302 amino acid residues with 34% identity with STC1 and eel STC. STC2 has a conserved N-glycosylation site and is rich in cysteines as is the case with other stanniocalcins. STC2 has the same exon-intron boundaries as STC1. The culture medium of STC2-transfected CHO cells inhibited the promoter activity of Na-phosphate cotransporter (NaPi-3) and also inhibited the phosphate uptake of a kidney cell line (OK cells). Therefore, the function of STC2 seems to be opposite to that of STC1 on Na-phosphate cotransporter. Northern blot analysis revealed multiple transcripts in number of human tissues with high levels being present in skeletal muscle and heart. STC2 was also expressed in mice widely and its expression was lower in hypophosphatemic mice (Hyp mice) in many organs. We have cloned a widely expressed new human stanniocalcin homologue which suppressed the expression of renal Na-phosphate cotransporter.
鲽鱼降钙素（STC）是一种由硬骨鱼类斯坦尼小体产生的钙和磷调节激素。最近报道了STC的哺乳动物同源物（STC1），它能刺激肾脏对磷的摄取。在此，我们报道了从人骨肉瘤cDNA文库中克隆出的第二种哺乳动物鲽鱼降钙素（STC2）。STC2有302个氨基酸残基，与STC1和鳗鱼STC的同源性为34%。与其他鲽鱼降钙素一样，STC2有一个保守的N-糖基化位点，且富含半胱氨酸。STC2与STC1具有相同的外显子-内含子边界。转染了STC2的CHO细胞的培养基抑制了钠-磷共转运蛋白（NaPi-3）的启动子活性，也抑制了一种肾细胞系（OK细胞）对磷的摄取。因此，STC2在钠-磷共转运蛋白上的功能似乎与STC1相反。Northern印迹分析显示，在多种人类组织中有多个转录本，在骨骼肌和心脏中含量较高。STC2在小鼠中也广泛表达，在许多器官中，其在低磷血症小鼠（Hyp小鼠）中的表达较低。我们克隆了一种广泛表达的新的人类鲽鱼降钙素同源物，它抑制了肾脏钠-磷共转运蛋白的表达。
