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ENDOCRINE PHYSIOLOGY AND METABOLISM
1Institute of Cellular and Organismic Biology, Academia Sinica, Taipei; 2Department of Biological Sciences and Technology, National University of Tainan, Tainan; 3Institute of Fishery Science, National Taiwan University, Taipei; and 4Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; and 5Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
Submitted 3 September 2008 ; accepted in final form 2 December 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.
Ca2+ uptake; Ca2+ influx
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