TY - JOUR T1 - Signaling Mechanisms Involved in Protease-Activated Receptor-1-Mediated Interleukin-6 Production by Human Gingival Fibroblasts JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 778 LP - 786 DO - 10.1124/jpet.104.068569 VL - 311 IS - 2 AU - Nobuhisa Tanaka AU - Takao Morita AU - Akihiro Nezu AU - Akihiko Tanimura AU - Itaru Mizoguchi AU - Yosuke Tojyo Y1 - 2004/11/01 UR - http://jpet.aspetjournals.org/content/311/2/778.abstract N2 - Human gingival fibroblasts (HGFs) express protease-activated receptor-1 (PAR-1) at high levels. In cultured HGFs, we studied the signaling pathway of thrombin-induced interleukin-6 (IL-6) production. The PAR-1 agonist peptide SFLLRN mimicked the thrombin-induced IL-6 production in the presence of amastatin, an aminopeptidase inhibitor. Thrombin or a combination of SFLLRN and amastatin also strikingly induced the expression of IL-6 mRNA. Although continuous exposure of HGFs to thrombin rapidly desensitized Ca2+ signaling, the cells did not lose their ability to produce IL-6 in response to thrombin. Similarly, although treatment of HGFs with BAPTA-AM [1,2-bis(O-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid-acetoxymethyl ester], an intracellular Ca2+ chelator, markedly attenuated the thrombin-induced increase in intracellular Ca2+ concentration, the same treatment did not suppress the thrombin-induced IL-6 production. However, thrombin-induced IL-6 production was strongly inhibited by the p38 mitogen-activated protein (MAP) kinase and tyrosine kinase inhibitors, and Western blotting analyses showed that thrombin stimulates p38 MAP kinase phosphorylation. Specific inhibitors that inhibit extracellular signal-regulated kinase 1/2 kinase, phosphatidylinositol 3-kinase, and RhoA kinase also partially suppressed the thrombin-induced IL-6 production, but the effects were smaller than those of the p38 MAP and tyrosine kinase inhibitors. Thus, thrombin induces HGFs to produce IL-6 by activating PAR-1, and the tyrosine kinase- and p38 MAP kinase-dependent pathways, rather than the Ca2+ signaling pathway, may play a crucial role in the IL-6 production. The American Society for Pharmacology and Experimental Therapeutics ER -