action of vitamin d and the receptor, vdra, in calcium handling in zebrafish (danio rerio)行动的维生素d受体,vdra、钙处理斑马鱼(鲐鱼类).pdfVIP

Action of Vitamin D and the Receptor, VDRa, in Calcium Handling in Zebrafish (Danio rerio) 1 1,2 3 2 1,2 Chia-Hao Lin , Che-Hsien Su , Deng-Yu Tseng , Feng-Chun Ding , Pung-Pung Hwang * 1 Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, ROC, 2 Institute of Fishery Science, National Taiwan University, Taipei, Taiwan, ROC, 3 Department of Biological Sciences and Technology, National University of Tainan, Tainan, ROC Abstract The purpose of the present study was to use zebrafish as a model to investigate how vitamin D and its receptors interact to control Ca2+ uptake function. Low-Ca2+ fresh water stimulated Ca2+ influx and expressions of epithelial calcium channel (ecac), vitamin D-25-hydroxylase (cyp2r1), vitamin D receptor a (vdra), and vdrb in zebrafish. Exogenous vitamin D increased Ca2+ influx and expressions of ecac and 25-hydroxyvitamin D -24-hydroxylase (cyp24a1), but downregulated 1a-OHase 3 (cyp27b1) with no effects on other Ca2+ transporters. Morpholino oligonucleotide knockdown of VDRa, but not VDRb, was found as a consequence of calcium uptake inhibition by knockdown of ecac, and ossification of vertebrae is impaired. Taken together, vitamin D-VDRa signaling may stimulate Ca2+ uptake by upregulating ECaC in zebrafish, thereby clarifying the Ca2+-handling function of only a VDR in teleosts. Zebrafish may be useful as a model to explore the function of vitamin D- VDR signaling in Ca2+ homeostasis and the related physiological processes in vertebrates. Citation: Lin C-H, Su C-H, Tseng