[Studies on gap junction formation and junctional communication between cultured endothelial cells and smooth muscle...

Gap junction (GJ) between two contacted cells is the structural basis of intercellular communication. Gap junction transfer plays an important role in regulation of cell proliferation. Cultured endothelial cells (EC) and smooth muscle cells (SMC) were injected with fluorescein Lucifer Yellow by iontophoretic injection, and examined under fluorescein microscope. We have demonstrated that there existed homologous and heterologous GJ and contact mediated dye transfer between cultured EC and SMC. LDL and insulin which promote SMC proliferation may inhibit the junctional communication between SMC and EC. Tumor promoter TPA induced almost complete inhibition of junctional communication between EC and SMC. The results indicate that normally regulative signals of metabolism and growth are transferred between EC and SMC via junctional communication to maintain the vessel wall homeostasis. High dosage LDL and insulin may keep SMC away from normal growth control and induce their proliferation by means of inhibiting junctional communication. It may be one of important mechanisms of atherogenesis.