Effects of thrombin receptor activating peptide on phosphoinositide hydrolysis and protein kinase C activation in cultured rat aortic smooth muscle cells: evidence for "tethered-ligand" activation of smooth muscle cell thrombin receptors.
Phosphoinositide hydrolysis and protein kinase C (PKC) activation were examined in response to treatment of rat aortic smooth muscle cells with alpha-thrombin and a seven amino acid thrombin receptor activating peptide (TRAP-7; SFLLRNP). alpha-Thrombin and TRAP-7 stimulated total inositol phosphate (IP) accumulation and phosphorylation of a specific endogenous substrate for activated PKC. Acetylated TRAP-7 and "reverse" TRAP (FSLLRNPNDKYEPF) were ineffective in stimulating signal transduction. The active site inhibitor, MD805 (argatroban), and the anion-binding exosite inhibitor, BMS 180,742, reduced the IP response to alpha-thrombin in a concentration-dependent manner. In contrast, the TRAP-7-induced IP response was not affected by either inhibitor. These data are consistent with the tethered-ligand hypothesis for thrombin receptor activation in rat aortic smooth muscle cells.
Department of Biochemistry, Bristol-Myers Squibb, Princeton, NJ 08543.
M L
ML
Webb
D S
DS
Taylor
C J
CJ
Molloy
D000818:Animals; D001011:Aorta; D001120:Arginine / Q000031:analogs & derivatives; D002478:Cells, Cultured / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism*; D010875:Pipecolic Acids / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface / Q000187:drug effects*; D018179:Receptors, Thrombin; D013449:Sulfonamides; D013917:Thrombin / Q000494:pharmacology*
D010446:Peptide Fragments; D010455:Peptides; D010716:Phosphatidylinositols; D010875:Pipecolic Acids; D011956:Receptors, Cell Surface; D018179:Receptors, Thrombin; D013449:Sulfonamides; C072032:thrombin receptor peptide (42-55); C072028:BMS 180742; D001120:Arginine; D011493:Protein Kinase C; D013917:Thrombin; C031942:argatroban