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

Abstract

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.