Neurons and ECM regulate occludin localization in brain endothelial cells

We report that extracellular matrix and neurons modulate the expression of occludin, one of the main components of tight junctions, by rat brain endot helial cells (RBE4.B). Of the three extracellular matrix proteins which we tested (collagen I, collagen IV, and laminin), collagen IV stimulated at th e best the expression of occludin mRNA. The corresponding protein, however, was not synthesized. Significant amounts of occludin accumulated only when RBE4.B cells were cultured on collagen IV-coated inserts, in the presence of cortical neurons, plated on laminin-coated companion wells. Finally, occ ludin segregated at the cell periphery, only when endothelial cells were co cultured with neurons for greater than or equal to 1 week. NeuroReport 11:1 081-1084 (C) 2000 Lippincott Williams & Wilkins.