| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1999: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Monocyte transmigration to the subendothelial space is a key step in atherogenesis and inflammation. Studies on MCP-1 and its receptor CCR2 knockout mice revealed that these molecules play a critical role in atherogenesis and immune response. However, molecular mechanisms of monocyte migration involved in MCP-1/CCR2 are not fully understood. Therefore, we first tried to investigate the role of tyrosine kinases, such as Pyk2 in MCP-1-mediated signal transduction in a monocytic cell line, THP-1 cells. We found that Pyk2 is tyrosine phosphorylated by MCP-1. Lyn, Shc, and paxillin were also found to be tyrosine phosphorylated by MCP-1. By immunoprecipitation and Western blot analysis we found that Pyk2 forms a complex with Lyn, Shc, and paxillin. However, the activation of Lyn was dependent on the kinase activity of Pyk2, but not that of Shc or paxillin. Further, we showed that MCP-1-dependent p38 MAP kinase activation was dependent on Pyk2 activation, but not ERK activation. Thus Pyk2 seems to be a platform signaling molecule in MCP-1-mediated signaling. Next, we examined the molecular mechanisms of integrin activation and chemotaxis. We showed that integrin activation by MCP-1 was blocked by a MEK inhibitor and that MCP-1-mediated chemotaxis was blocked by a p38 MAP kinase inhibitor and a Rho inhibitor. Our data demonstrate that MCP-1-mediated integrin activation and chemotaxis are regulated by two independent signaling pathways.
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