Regulation of the desmosome-intermediate filament linkage enables an adaptive mechano-response within the stratified epidermis

Abstract

Skin, the bodys largest mechanosensitive organ, relies on a tension gradient across epidermal layers to maintain structure and function, but how mechanical force contributes to epidermal development and disease pathogenesis is poorly understood. By anchoring intermediate filaments (IF) to the plasma membrane, desmosomes, the most abundant intercellular junctions in the epidermis, help create a supracellular scaffolding that provides mechanical resilience to the tissue. However, the contribution of the desmosome-IF network to the epidermal response to mechanical strain remains unknown. Here we show that the desmosome-IF connection is not only required to induce a proper cellular mechano-response but is actively strengthened in response to stretch through the PP2A-mediated phospho-regulation of the cytoskeletal linker protein desmoplakin (DP). Additionally, we show in human skin dephosphorylated DP localizes to high tension layers, suggesting this mechano-response mechanism is coordinated with the epidermal tension gradient. Furthermore, in models of Carvajal syndrome, a cardio-cutaneous disorder caused by truncating DP mutations, cells lose mechano-responsive behavior and exhibit abnormal morphology in high-tension epidermal layers. Together, these findings identify the DP-IF network as a key component of the response to mechanical strain and show that its disruption compromises epidermal homeostasis and contributes to disease pathogenesis.