Dynamic Superresolution Imaging of Endogenous Proteins on Living Cells at Ultra-High Density

Versatile superresolution imaging methods, able to give dynamic information of endogenous molecules at high density, are still lacking in biological science. Here, superresolved images and diffusion maps of membrane proteins are obtained on living cells. The method consists of recording thousands of single-molecule trajectories that appear sequentially on a cell surface upon continuously labeling molecules of interest. It allows studying any molecules that can be labeled with fluorescent ligands including endogenous membrane proteins on living cells. This approach, named universal PAINT (uPAINT), generalizes the previously developed point-accumulation-for-imaging-in-nanoscale-topography (PAINT) method for dynamic imaging of arbitrary membrane biomolecules. We show here that the unprecedented large statistics obtained by uPAINT on single cells reveal local diffusion properties of specific proteins, either in distinct membrane compartments of adherent cells or in neuronal synapses.