Expression of adhesion molecules and growth factors in vascular endothelial cell

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Endothelial-leukocyte adhesion molecules such as VCAM-1 and ICAM-1, have been implicated in recruitment of circulating monocytes and T-lymphocytes to atherosclerotic lesions. In addition, smooth muscle growth factors, including PDGF A and B chains and HB-EGF, appear to play crucial role in migration and proliferation of medical smooth muscle cells into atherosclerotic intima. Lysophosphatidylcholine (Ox-LDL), can transcriptionally induce expression of VCAM-1, ICAM-1, PFGF, and HB-EGF in cultured vascular endothelial cells; therefore, we sought to define transcriptional and sibnal transduction mechanisms involved in lyso-PC-induced expression. We have found that elevated levels of intracelluar cyclic AMP inhibited lyso-PC-induced expression of PDGF and ICAM-1. Furthermore, lyso-PC-induced expression of PDGF was dependent upon protein tyrosine phosphorylation. We, therefore, explored the protein that can rapidly phosphorylated in the tyrosine residue. We revealed that a protein with a molecular mass of 130kDa, which was designated p130, was rapidly and transiently tyrosine phosphorylated by lyso-PC. By use of immunoblotting and immunoprecipitation, we have identified p130 as PECAM-1 which was expressed on the intercellular junction of cultured endothelial cells. Our study also have demonstrated that MAP kinases, such as ERK and JNK, were activated by lyso-PC, which appeared to depend upon protein tyrosine phosphorylation.