Palmitoylation of plakophilin is required for desmosome assembly

Abstract

Desmosomes are prominent adhesive junctions found in various epithelial tissues. The cytoplasmic domains of desmosomal cadherins interact with a host of desmosomal plaque proteins, including plakophilins, plakoglobin and desmoplakin, which, in turn, recruit the intermediate filament cytoskeleton to sites of cell-cell contact. Although the individual components of the desmosome are known, mechanisms regulating the assembly of this junction are poorly understood. Protein palmitoylation is a posttranslational lipid modification that plays an important role in protein trafficking and function. Here, we demonstrate that multiple desmosomal components are palmitoylated in vivo. Pharmacologic inhibition of palmitoylation disrupts desmosome assembly at cell-cell borders. We mapped the site of plakophilin palmitoylation to a conserved cysteine residue present in the armadillo repeat domain. Mutation of this single cysteine residue prevents palmitoylation, disrupts plakophilin incorporation into the desmosomal plaque and prevents plakophilindependent desmosome assembly. Finally, plakophilin mutants unable to become palmitoylated act in a dominant-negative manner to disrupt proper localization of endogenous desmosome components and decrease desmosomal adhesion. Taken together, these data demonstrate that palmitoylation of desmosomal components is important for desmosome assembly and adhesion.

Palmitoylation of Progressive Rod-Cone Degeneration (PRCD) Regulates Protein Stability and Localization

“…Transient transfection of PRCD wild type and C2Y mutant with 70% confluence hRPE1 cells in 100-mm tissue culture dishes was performed with 100 M 17-ODYA or vehicle DMSO for 48 h (30,46). To facilitate dissolution of 17-ODYA in the medium, 75 l of 20 mM 17-ODYA stock in DMSO (or vehicle DMSO only) was mixed with 150 l of 10% fatty acid-free bovine serum albumin (Sigma) and was added to 15 ml of DMEM, and the mixture was vortexed prior to being added to cells.…”

Desmosomes in acquired disease

“…Recent studies have supported a role for raft association of desmosomal components in regulating adhesion. All desmosomal proteins have been shown to be raft-associated under normal cell culture conditions(Brennan, et al, 2012, Nava, et al, 2007, Resnik, et al, 2011, Roberts, et al, 2014, Stahley, et al, 2014). Functional rafts are also required for desmosome assembly and adhesion (Resnik, et al, 2011, Stahley, et al, 2014).…”

Remodeling of keratin-coupled cell adhesion complexes

“…Integrin a6 is also addressed from the lateral membranes to the basal membrane by the regulators of intracellular trafficking Lgl2 and Clint1. [76,77]. These highly organized cholesterol-enriched sub-regions of the plasma membrane promote stabilization and clustering of transmembrane proteins [78] ( Figure 2).…”