Effects of stanniocalcin 1 on calcium uptake in zebrafish (Danio rerio) embryo

Tseng D-Y, Chou M-Y, Tseng Y-C, Hsiao C-D, Huang C-J, Kaneko T, Hwang P-P. Effects of stanniocalcin 1 on calcium uptake in zebrafish ( Danio rerio) embryo. Am J Physiol Regul Integr Comp Physiol 296: R549-R557, 2009. First published December 10, 2008; doi: 10.1152/ajpregu.90742.2008. -Stanniocalcin (STC) formerly called hypocalcin or teleocalcin, is a 50-kDa disulfide-linked homodimeric glycoprotein that was originally identified in fish and secreted from the corpuscles of Stannius (CS). One of the main functions of STC-1 is Ca2+ uptake inhibition; however, the mechanisms remain unknown. In the present study, we provide molecular evidence to elucidate how zebrafish STC-1 regulates Ca2+ uptake in zebrafish embryos. In a wide variety of tissues including the kidney, brain, gill, muscle, and skin, zstc-1 was expressed. Incubating zebrafish embryos in low-Ca2+ (0.02 mM) freshwater stimulated whole body Ca2+ influx and zebrafish epithelial Ca2+ channel (zECaC) mRNA expression, while downregulated zstc-1 expression. A morpholino microinjection approach was used to knockdown the zSTC-1 protein, and the results showed that the Ca2+ content, Ca2+ influx, and zECaC mRNA expression all increased in morphants. These data suggest that zSTC-1 negatively regulates ECaC gene expression to reduce Ca2+ uptake in zebrafish embryos.