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XB-ART-5790
J Clin Invest 2003 Feb 01;1113:371-9. doi: 10.1172/JCI16711.
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P2Y6 receptor mediates colonic NaCl secretion via differential activation of cAMP-mediated transport.

Köttgen M, Löffler T, Jacobi C, Nitschke R, Pavenstädt H, Schreiber R, Frische S, Nielsen S, Leipziger J.


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Extracellular nucleotides are important regulators of epithelial ion transport. Here we investigated nucleotide-mediated effects on colonic NaCl secretion and the signal transduction mechanisms involved. Basolateral UDP induced a sustained activation of Cl(-) secretion, which was completely inhibited by 293B, a specific inhibitor of cAMP-stimulated basolateral KCNQ1/KCNE3 K(+) channels. We therefore speculated that a basolateral P2Y(6) receptor could increase cAMP. Indeed UDP elevated cAMP in isolated crypts. We identified an epithelial P2Y(6) receptor using crypt [Ca(2+)](i) measurements, RT-PCR, and immunohistochemistry. To investigate whether the rat P2Y(6)elevates cAMP, we coexpressed the P2Y(1) or P2Y(6) receptor together with the cAMP-regulated cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel in Xenopus oocytes. A two-electrode voltage clamp was used to monitor nucleotide-induced Cl(-) currents. In oocytes expressing the P2Y(1) receptor, ATP transiently activated the endogenous Ca(2+)-activated Cl(-) current, but not CFTR. In contrast, in oocytes expressing the P2Y(6)receptor, UDP transiently activated the Ca(2+)-activated Cl(-) current and subsequently CFTR. CFTR Cl(-) currents were identified by their halide conductance sequence. In summary we find a basolateral P2Y(6) receptor in colonic epithelial cells stimulating sustained NaCl secretion by way of a synergistic increase of [Ca(2+)](i) and cAMP. In support of these data P2Y(6) receptor stimulation differentially activates CFTR in Xenopus oocytes.

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Species referenced: Xenopus
Genes referenced: camp cftr kcne3 kcnq1 p2ry6

References [+] :
Bailey, Evidence for basolateral P2Y(6) receptors along the rat proximal tubule: functional and molecular characterization. 2001, Pubmed