Visualization of intracellular diffusion in endothelial cell using photochromic fluorescent protein

During cell migration, many molecules like proteins are polarized in endothelial cell (EC). The polarized distribution induces various cellular functions among different locations in EC. In recent studies, many biological processes that is strongly related with polarization on plasma membrane were revealed. However, about whether the intracellular events are affected by cell polarization is not well known. To define being differences of molecular property among locations, we visualized molecular diffusion at various polarization domains of cytoplasm, using photoactivation technique with photocromic fluorescent protein "Dronpa". We confirmed that photoactivation technique enables us to visualize fast protein movements and Dronpa enables us to repeat the measurement of intracellular diffusion in the same cell. As a result, we indicated that diffusion coefficient is D=8.2 ±3.1 μm²/s (mean±S. D.) and there seemed to be differences of diffusion coefficient among various domains in endothelial cell.