Proteomic analysis of the desmosome identifies novel components required for skin integrity

Abstract

Desmosomes are cell-cell adhesions necessary for the maintenance of tissue integrity in the skin and the heart. While the core components of the desmosome have been identified, peripheral components that modulate canonical desmosome functions or that have noncanonical roles remain largely unexplored. Here we used targeted proximity labeling approaches to elaborate the desmosome proteome in epidermal keratinocytes. Quantitative mass spectrometry analysis identified all core desmosome proteins while uncovering a diverse network of new constituents with broad molecular functions. By individually targeting the inner and outer dense plaques, we additionally define proteins enriched in these subcompartments. We validated a number of these novel desmosome-associated proteins and find that many show a dependence upon the core desmosomal protein, desmoplakin, for their localization. We further explored the mechanism of localization and function of two novel desmosome-associated adaptor proteins that we identified, Crk and Crkl. These proteins interacted with Dsg1 and require both Dsg1 and desmoplakin for robust cortical localization. Epidermal deletion of both Crk and CrkL in mice resulted in perinatal lethality with defects in desmosome morphology and keratin organization, thus demonstrating the utility of this dataset in identifying novel proteins required for desmosome-dependent epidermal integrity.