P2Y(2) receptor of MDCK cells: cloning, expression, and cell-specific signaling

Madin-Darby canine kidney (MDCK)-D1 cells, a canine renal epithelial cell l ine, co-express at least three different P2Y receptor subtypes: P2Y(1), P2Y (2), and P2Y(11) (24). Stimulation of P2Y receptors in these cells results in the release of arachidonic acid (AA) and metabolites and the elevation o f intracellular cAMP. To define in more precise terms the signaling contrib uted by the MDCK-D1 P2Y(2) (cP2Y(2)) receptor, we have cloned and heterolog ously expressed it in CF2Th (canine thymocyte) cells, a P2Y(2)-null cell. A nalysis by RT-PCR indicated that canine P2Y(2) receptors are expressed in s keletal muscle, spleen, kidney, lung, and liver. When expressed in CF2Th ce lls, cP2Y(2) receptors promoted phospholipase C-mediated phosphatidylinosit ol (PI) hydrolysis [uridine 5'-triphosphate greater than or equal to ATP > adenosine 5'-diphosphate. 2MT-ATP] and mobilization of intracellular Ca2+. In contrast to their actions in MDCK-D1 cells, cP2Y(2) receptors did not st imulate formation of cAMP or AA release when expressed in CF2Th cells. The data indicate that cell setting plays an essential role in the ability of P 2Y receptors to regulate AA release and cAMP formation. In particular, rena l epithelial cells preferentially express components critical for cP2Y(2)-i nduced cAMP formation, including the expression of enzymes involved in the generation and metabolism of AA and receptors that respond to PGE(2).