title: Activation of cathepsin B involved in enkephalin production by bradykinin and its cleavage products in cultured fibroblasts of the rat dental pulp.
abstract: Mechanisms of cathepsin B activation involved in methionine-enkephalin (ME) production induced by bradykinin (BK), des-Arg9-BK or L-arginine (L-Arg) were studied using cultured fibroblasts of the rat dental pulp, especially from a viewpoint of intracellular signal transduction. BK, des-Arg9-BK, L-Arg or cysteine enhanced the release of ME-like peptides from the cells, and the release of ME-like peptides induced by des-Arg9-BK was inhibited by des-Arg9-[Leu8]-BK (BK B1-receptor antagonist) and E-64 (a specific inhibitor of cysteine proteinases). The activation of cathepsin B by BK or des-Arg9-BK was inhibited by des-Arg9-[Leu8]-BK or islet-activating protein (IAP), and the activation of cathepsin B by L-Arg was inhibited by Leu-Arg (kyotorphin-receptor antagonist) or Botulinum C3-enzyme. The activation of cathepsin B by those stimulants was dependent on calcium ion. These results suggest that the ME production by BK or des-Arg9-BK may be mediated by Ca(2+)-dependent cathepsin B activation through B1-receptors and IAP-sensitive G-proteins, whereas the production by L-Arg may be mediated by Ca(2+)-dependent cathepsin B activation through kyotorphin-receptor and Botulinum C3-enzyme-sensitive G-proteins. On the other hand, the activation of cathepsin B was inhibited by neomycin B (phospholipase C inhibitor) and various serine/threonine kinase inhibitors. These results indicate that phospholipase C and serine/threonine kinases are involved in the activation of cathepsin B by BK, des-Arg9-BK or L-Arg. Genistein inhibited the activation of cathepsin B by des-Arg9-BK or L-Arg in a different fashion, suggesting that tyrosine kinase(s) is also involved in the activation. Cathepsin B activation by BK or L-Arg but not des-Arg9-BK was inhibited by L-NMMA (inhibitor of NO synthesis), and the activation by L-Arg was enhanced by beta-glycerophosphate (beta-GP: inhibitor of phosphatases), while the activation by BK or des-Arg9-BK was inhibited by beta-GP. These results suggest that BK-induced cathepsin B activation in the fibroblasts may be due to a combined effect of des-Arg9-BK and L-Arg.
authors.affiliation: Department of Pharmacology, Osaka University Faculty of Dentistry, Japan.
authors.forename: B F
authors.initials: BF
authors.lastname: Zhu
authors.forename: T
authors.initials: T
authors.lastname: Kudo
authors.forename: S
authors.initials: S
authors.lastname: Maeda
authors.forename: R
authors.initials: R
authors.lastname: Inoki
mesh_terms: D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001920:Bradykinin / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002478:Cells, Cultured; D003782:Dental Pulp / Q000166:cytology / Q000378:metabolism*; D004744:Enkephalin, Methionine / Q000096:biosynthesis*; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000502:physiology; D005994:Glycerophosphates / Q000494:pharmacology; D008297:Male; D037342:Pertussis Toxin; D011494:Protein Kinases / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D010738:Type C Phospholipases / Q000502:physiology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D005994:Glycerophosphates; D010566:Virulence Factors, Bordetella; D004744:Enkephalin, Methionine; D001120:Arginine; D037342:Pertussis Toxin; D011494:Protein Kinases; D010738:Type C Phospholipases; D002401:Cathepsin B; D019204:GTP-Binding Proteins; D001920:Bradykinin; D002118:Calcium