Alpha-thrombin and trypsin use different receptors to stimulate arachidonic acid metabolism.
Rat liver cells (the C-9 cell line) are stimulated to metabolize arachidonic acid by alpha-thrombin, its receptor polypeptide, gamma-thrombin, and trypsin. Prostaglandin (PG) I2 synthesis stimulated by alpha-thrombin is inhibited by dansylarginine N-(3-ethyl-1,5-pentanediyl) amide (DAPA), by hirudin, by the synthetic tyrosine-sulfated dodecapeptide corresponding to residues 53-64 of hirudin (hirugen), by the Tyr(SO3H)63-hirudin fragment 54-65 and by rabbit lung thrombomodulin. Stimulation of arachidonic acid metabolism by the receptor octapeptide, SFLLRNPN, is not affected by DAPA or hirudin. gamma-Thrombin stimulates arachidonic acid metabolism but at 300 to 400-fold higher concentrations. Trypsin stimulates arachidonic acid metabolism. Trypsin's proteolytic activity is required--its ability to stimulate is abolished if it is incubated with Na-p-tosyl-L-lysine chloromethyl ketone (TLCK) or bovine pancreatic trypsin inhibitor. Prior treatment of the rat liver cells with alpha-thrombin blocks subsequent stimulation by alpha-thrombin, but not by trypsin, whereas prior treatment with trypsin blocks subsequent stimulation by trypsin, but not the activity stimulated by alpha-thrombin. Prior treatment of the cells with the serine-proteases, chymotrypsin, pancreatic or neutrophil elastase and thrombocytin from Bothrups atrox venom, block alpha-thrombin's activation of PGI2 production, but not the activity stimulated by trypsin. These findings indicate that alpha-thrombin and trypsin stimulate PGI2 production via different receptors.
Levine
L
L
Department of Biochemistry, Brandeis University, Waltham, MA 02254.
D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002478:Cells, Cultured; D003619:Dansyl Compounds / Q000494:pharmacology; D011464:Epoprostenol / Q000378:metabolism*; D006629:Hirudins / Q000031:analogs & derivatives / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D044464:Receptor, PAR-2; D011956:Receptors, Cell Surface / Q000145:classification / Q000378:metabolism*; D018179:Receptors, Thrombin / Q000378:metabolism; D013917:Thrombin / Q000378:metabolism*; D018180:Thrombomodulin / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism*
D003619:Dansyl Compounds; D006629:Hirudins; D010446:Peptide Fragments; D044464:Receptor, PAR-2; D011956:Receptors, Cell Surface; D018179:Receptors, Thrombin; D018180:Thrombomodulin; C062510:hirugen; C019162:dansylarginine N-(3-ethyl-1,5-pentanediyl)amide; D001120:Arginine; D011464:Epoprostenol; D014357:Trypsin; D013917:Thrombin