Positive cooperativity between the thrombin and bradykinin B2 receptors enhances arachidonic acid release
Open Access
- 1 March 2006
- journal article
- research article
- Published by American Physiological Society in American Journal of Physiology-Heart and Circulatory Physiology
- Vol. 290 (3) , H948-H958
- https://doi.org/10.1152/ajpheart.00868.2005
Abstract
Bradykinin (BK) or kallikreins activate B2 receptors (R) that couple Gαi and Gαq proteins to release arachidonic acid (AA) and elevate intracellular Ca2+ concentration ([Ca2+]i). Thrombin cleaves the protease-activated-receptor-1 (PAR1) that couples Gαi, Gαq, and Gα12/13 proteins. In Chinese hamster ovary cells stably transfected with human B2R, thrombin liberated little AA, but it significantly potentiated AA release by B2R agonists. We explored mechanisms of cooperativity between constitutively expressed PAR1 and B2R. We also examined human endothelial cells expressing both Rs constitutively. The PAR1 agonist hexapeptide (TRAP) was as effective as thrombin. Inhibitors of components of Gαi, Gαq, and Gα12/13 signaling pathways, and a protein kinase C (PKC)-α inhibitor, Gö-6976, blocked potentiation, while phorbol, an activator, enhanced it. Several inhibitors, including a RhoA kinase inhibitor, a [Ca2+]i antagonist, and an inositol-(1,3,4)-trisphosphate R antagonist, reduced mobilization of [Ca2+]i by thrombin and blocked potentiation of AA release by B2R agonists. Because either a nonselective inhibitor (isotetrandrine) of phospholipase A2 (PLA2) or a Ca2+-dependent PLA2 inhibitor abolished potentiation of AA release by thrombin, while a Ca2+-independent PLA2 inhibitor did not, we concluded that the mechanism involves Ca2+-dependent PLA2 activation. Both thrombin and TRAP modified activation and phosphorylation of the B2R induced by BK. In lower concentrations they enhanced it, while higher concentrations inhibited phosphorylation and diminished B2R activation. Protection of the NH2-terminal Ser1-Phe2 bond of TRAP by an aminopeptidase inhibitor made this peptide much more active than the unprotected agonist. Thus PAR1 activation enhances AA release by B2R agonists through signal transduction pathway.Keywords
This publication has 36 references indexed in Scilit:
- Protein Kinase Cα Phosphorylates the TRPC1 Channel and Regulates Store-operated Ca2+ Entry in Endothelial CellsPublished by Elsevier ,2004
- Sensitization of Epidermal Growth Factor-induced Signaling by Bradykinin Is Mediated by c-SrcJournal of Biological Chemistry, 2004
- Thrombin Receptors Activate Go Proteins in Endothelial Cells to Regulate Intracellular Calcium and Cell Shape ChangesPublished by Elsevier ,2002
- Protease‐Activated Receptors: A Means of Converting Extracellular Proteolysis into Intracellular SignalsIUBMB Life, 2002
- Replacement of the Transmembrane Anchor in Angiotensin I-converting Enzyme (ACE) with a Glycosylphosphatidylinositol Tail Affects Activation of the B2 Bradykinin Receptor by ACE InhibitorsJournal of Biological Chemistry, 2000
- Expression of Rat Kallikrein and Epithelial Polarity in Transfected Madin-Darby Canine Kidney CellsHypertension, 1995
- The G proteins of the G alpha i and G alpha q family couple the bradykinin receptor to the release of endothelium-derived relaxing factor.Journal of Clinical Investigation, 1993
- Mediation of growth factor induced DNA synthesis and calcium mobilization by Gq and Gi2.The Journal of cell biology, 1993
- Domains specifying thrombin–receptor interactionNature, 1991
- Pertussis toxin inhibits EGF-, phorbol ester- and insulin-stimulated DNA synthesis in BALBc3T3 cells: Evidence for post-receptor activation of G iαBiochemical and Biophysical Research Communications, 1990