[Regulation of PTH gene by calcium and phosphate]

The mechanism of PTH gene regulation by extracellular calcium and phosphate is currently divided into two categories. One is through the transcriptional event in which negative calcium responsive element conserved in the 5'-flanking region of the PTH genes of various species and its binding protein play an crucial role. Another hypothesis is that regulation by calcium and phosphate, especially the effect of hypocalcemia and hypophosphatemia, is triggered by the post-transcriptional regulation of the PTH gene. Although both hypotheses are not mutually exclusive, in vivo effect of low calcium and low phosphate is likely to be exerted chiefly by the post-transcriptional mechanism. However, both studies have never linked their findings to the function of calcium sensing receptors. Here, I will review the current understanding of these molecular events regarding physiological regulation of the PTH gene.