Prostaglandin D2 receptor-mediated desensitization of the alpha isoform of the human thromboxane A2 receptor

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Title: Prostaglandin D2 receptor-mediated desensitization of the alpha isoform of the human thromboxane A2 receptor
Authors: Foley, John F.
Kelley-Hickie, Leanne P.
Kinsella, B. Therese
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Date: 15-Jul-2001
Online since: 2011-09-22T13:43:09Z
Abstract: Thromboxane (TX) A2 and prostaglandin (PG) D2 mediate opposing actions in platelets and in vascular and non-vascular smooth muscle. Here, we investigated the effects of stimulation of the PGD2 receptor (DP) on signaling by the TXA2 receptor (TP) expressed in human platelets and in human embryonic kidney (HEK) 293 cells over-expressing the individual TPalpha and TPbeta isoforms. In platelets, the selective DP agonist BW245C abolished TP-mediated mobilization of intracellular calcium ([Ca2+]i) and inhibited platelet aggregation in response to the TXA2 mimetic U46619. DP-mediated desensitization of TP signaling in platelets was prevented by pre-treatment with the cAMP-dependent PKA inhibitor, H-89, but was unaffected by the PKC inhibitor GF 109203X. In HEK 293 cells signaling by TPalpha, but not TPbeta, was subject to DP mediated desensitization in a PKA dependent, PKC independent manner. U46619-induced signaling by TP-328, a truncated variant of TP containing only those residues common to TPalpha and TPbeta, was insensitive to prior DP stimulation indicating that the carboxyl terminal tail of TPalpha contains the target site(s) for DP-mediated desensitization. Mutation of Ser329 to Ala329 within a consensus PKA site in TPalpha rendered the mutant TPalphaS329A insensitive to BW245C-mediated desensitization. Whole cell phosphorylation assays established that TPalpha, but not TPbeta or TPalphaS329A, was subject to DP-mediated phosphorylation and that TPalpha phosphorylation was blocked by the PKA inhibitor H-89. These data establish that TPalpha, but not TPbeta, is subject to DP mediated cross desensitization, which occurs through direct PKA mediated phosphorylation of TPalpha at Ser329.
Funding Details: Health Research Board
Type of material: Journal Article
Publisher: Elsevier
Journal: Biochemical Pharmacology
Volume: 62
Issue: 2
Start page: 229
End page: 239
Copyright (published version): 2001 Elsevier Science Inc.
Keywords: Thromboxane A2 receptorProstaglandin D2 receptorDesensitisationProtein kinase APhosphorylationG protein coupled receptor
Subject LCSH: Thromboxanes
Protein kinases
DOI: 10.1016/S0006-2952(01)00661-X
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Language: en
Status of Item: Peer reviewed
Appears in Collections:Conway Institute Research Collection
Biomolecular and Biomedical Science Research Collection

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