Thrombin-Stimulated Proliferation of Cultured Human Synovial Fibroblasts Through Proteolytic Activation of Proteinase-Activated Receptor-1

• Published in: Journal of Pharmacological Sciences Vol. 108; no. 1; pp. 104 - 111
• Main Authors: Furuhashi, Ikue, Abe, Kazuki, Sato, Toshitsugu, Inoue, Hideo
• Format: Journal Article
• Language: English
• Published: Japan Elsevier B.V 2008; The Japanese Pharmacological Society; Elsevier
• Subjects: Calcium - physiology; Calcium Signaling - drug effects; Cell Proliferation - drug effects; Cells, Cultured; Enzyme Inhibitors - pharmacology; Enzyme-Linked Immunosorbent Assay; Fibroblasts - drug effects; Hemostatics - pharmacology; Humans; Intercellular Signaling Peptides and Proteins - metabolism; PAR mRNA; proliferation; proteinase-activated receptor (PAR)-1; Receptor, PAR-1 - biosynthesis; Receptor, PAR-1 - physiology; Receptors, Thrombin - biosynthesis; Receptors, Thrombin - physiology; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction - drug effects; Stimulation, Chemical; synovial fibroblast; Synovial Fluid - cytology; thrombin; Thrombin - pharmacology; PAR mRNA; proteinase-activated receptor (PAR)-1; thrombin; proliferation; synovial fibroblast
• ISSN: 1347-8613; 1347-8648
• DOI: 10.1254/jphs.08126FP

We examined the mechanism of thrombin on proliferation of synovial fibroblasts obtained from rheumatoid arthritis (RA). Thrombin concentration-dependently induced proliferation of synovial fibroblasts. Proliferation in response to thrombin (10 U /ml) was completely blocked by hirudin. TP367 and TP508, peptides corresponding to 2 noncatalytic regions of thrombin, failed to induce cell proliferation. Thrombin did not induce the production of basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF), and epidermal growth factor (EGF) in synovial fibroblasts. Expression of proteinase-activated receptor (PAR)-1 and PAR-3 mRNAs was observed in synovial fibroblasts. Thrombin and PAR-1 agonist peptide (AP), but not PAR-3 AP, induced intracellular calcium mobilization. PAR-1 AP induced cell proliferation whereas PAR-3 AP and PAR-4 AP had no effect on proliferation. Pertussis toxin (PTX), a Giα protein inhibitor; wortmannin, a PI (phosphatidylinositol) 3-kinase inhibitor; and PD98059, a specific MEK [mitogen-activated protein (MAK) kinase kinase] inhibitor, inhibited the thrombin-induced cell proliferation. Furthermore, the proliferation of synovial fibroblasts was suppressed by U-73122, a PLC (phospholipase C) inhibitor; 2-APB, an antagonist of InsP3 (inositol 1,4,5-triphosphate) receptor; and GF-109203X, a PKC (protein kinase C) inhibitor. These results suggest that thrombin induces the proliferation of RA synovial fibroblasts through the activation of PAR-1, leading to the PTX-sensitive G proteins – PI3 kinase pathway and PTX-insensitive G proteins – PLC (InsP3 receptor) Ca2+-PKC branch.