Glycocalyx micro- and nanodomains in cell-cell and cell-matrix interactions revealed by enhanced click chemistry.

The glycocalyx consists of glycoproteins, glycolipids and extracellular polysaccharides at the cell surface which mediate viscoelastic and electrostatic barrier function. In molecular interactions, the glycocalyx is thought to segregate locally to facilitate receptor-ligand binding, yet high-resolution maps of glycocalyx domains in cell-cell and cell-matrix interactions are lacking. We here apply TMTH-sulfoximine (THS)-based biorthogonal chemistry in live-cell culture and demonstrate enhanced glycocalyx detection, compared to established dibenzocyclooctyne-based labeling. Using superresolution microscopy in cancer cells, we identify micron-scale diminished glycocalyx in cell-cell contacts and depletion in protrusions at the leading and trailing edges and membrane blebs when cells invade 3D fibrillar matrix. At contacts to collagen fibrils, focal integrin clusters segregate ~350 nm outward from the glycocalyx level, forming adhesion sites of low glycocalyx content. Thus, we identify micro- and nanodomains with altered glycocalyx density using THS-based bioorthogonal labeling of live cells, implicating local glycocalyx downregulation in functional cell-cell and cell-matrix interactions.