Plasma membrane Ca2+ ATPase Atp2b1a regulates bone mineralization in zebrafish

The zebrafish transgenic lines provide a possibility to observe the development of tissues and organs in real time. Using the reporter line for the zebrafish plasma membrane Ca2+ ATPase (SqET4), we detected its expression in the epithelium of pharyngeal teeth and analyzed its role in their calcification and that of cranial bones. atp2b1a's expression in the pharyngeal epithelium is faithfully recapitulated in the SqET4 transgenics by GFP expression. We showed by morpholino knockdown of Atp2bla translations as well as chemical inhibition of Atp2bla pump activity using carboxyeosin, that its activity is required to facilitate calcification of the developing pharyngeal teeth by the dental epithelium. Atp2b1 a could be required during calcification of endochondral bones, where it acts at two levels: 1) by exporting Ca2+ from ameloblasts, it provides raw material for calcifying the pharyngeal teeth by adjacent odontoblasts; and 2) by regulating terminal differentiation of pharyngeal epithelial cells, including ameloblasts required for tissue hyper-mineralization. atp2b1a's expression in the pharyngeal epithelium is regulated by the homeodomain transcription factor dix2b. (C) 2013 Elsevier Inc. All rights reserved.