Nanostructure of the desmosomal plaque

Abstract

Desmosomes are considered one of the most important intercellular junctions with respect to mechanical strength. Therefore, their spatial distribution and structure is of interest with respect to understanding both healthy and diseased tissue. Previous studies have imaged desmosomes in tissue slices using transmission electron microscopy, or low-resolution confocal images, but both these techniques lack the ability to resolve the 3-dimensional structure of the desmosomes. In this work it was possible to determine the 3D-nanostructure of single desmosomal complexes in both mouse and human epidermis, by 3D stimulated emission depletion (STED) microscopy. STED images of desmoplakin and the desmosomal cadherin, desmoglein revealed that desmosomes form ring-like structures, distributed over the cell surface, with diameters of around 1 m. STED images of the tight junction plaque protein ZO1 also displayed ring formations, suggesting a common structure for intercellular junctions. Measurements of the desmosomal plaque protein, desmoplakin showed an increased intercellular plaque distance during the stratum basale (0.23{+/-}0.027{micro}m) to stratum spinosum (0.28{+/-}0.039 {micro}m) transition.