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XB-ART-55896
JCI Insight 2019 Apr 23;5. doi: 10.1172/jci.insight.128013.
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Activation of the calcium sensing receptor attenuates TRPV6-dependent intestinal calcium absorption.

Lee JJ , Liu X , O'Neill D , Beggs MR , Weissgerber P , Flockerzi V , Chen XZ , Dimke H , Alexander RT .


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Plasma calcium (Ca2+) is maintained by amending the release of parathyroid hormone and through direct effects of the Ca2+ sensing receptor (CaSR) in the renal tubule. Combined, these mechanisms alter intestinal Ca2+ absorption by modulating 1,25-dihydroxy vitamin D3 production, bone resorption, and renal Ca2+ excretion. The CaSR is a therapeutic target in the treatment of secondary hyperparathyroidism and hypocalcemia a common complication of calcimimetic therapy. The CaSR is also expressed in intestinal epithelium, however, a direct role in regulating local intestinal Ca2+ absorption is unknown. Chronic CaSR activation decreased expression of genes involved in Ca2+ absorption. In Ussing chambers, increasing extracellular Ca2+ or basolateral application of the calcimimetic cinacalcet decreased net Ca2+ absorption across intestinal preparations acutely. Conversely, Ca2+ absorption increased with decreasing extracellular Ca2+ concentration. These responses were absent in mice expressing a non-functional TRPV6, TRPV6D541A. Cinacalcet also attenuated Ca2+ fluxes through TRPV6 in Xenopus oocytes when co-expressed with the CaSR. Moreover, the phospholipase C inhibitor, U73122, prevented cinacalcet-mediated inhibition of Ca2+ flux. These results reveal a regulatory pathway whereby activation of the CaSR in the basolateral membrane of the intestine directly attenuates local Ca2+ absorption via TRPV6 to prevent hypercalcemia and help explain how calcimimetics induce hypocalcemia.

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Species referenced: Xenopus
Genes referenced: casr trpv6
GO keywords: regulation of calcium ion export across plasma membrane

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References [+] :
Alexander, Klotho prevents renal calcium loss. 2009, Pubmed