Biology subjects

Vielmuth, F.

Publications and source records attributed to Vielmuth, F..

3 recordsLinked to original sources

bioRxiv2022

Apremilast prevents blistering in human epidermis by stabilization of keratinocyte adhesion in pemphigus.

Pemphigus vulgaris (PV) is a life-threatening blistering skin disease caused by autoantibodies (PV-IgG) destabilizing desmosomal adhesion. Current therapies focus on suppression of autoantibody formation and thus treatments directly stabilizing keratinocyte adhesion would fulfill an unmet medical need. We here demonstrate that apremilast, a phosphodiesterase 4 inhibitor used e.g. in psoriasis, prevents blistering in PV. Apremilast abrogated PV-IgG-induced loss of keratinocyte cohesion in ex-vivo epidermis and in vitro. This was paralleled by inhibition of keratin retraction and desmosome splitting but affected neither desmoglein (Dsg) depletion nor Dsg3 binding properties. Apremilast induced phosphorylation of plakoglobin at serine 665 - a mechanisms which is known to stabilize cardiomyocyte cohesion. Interestingly, keratinocytes phospho-deficient at this side showed altered organization of Dsg1, Dsg3 and keratin filaments and impaired adhesion, which was not rescued by apremilast. These data identified a new mechanism of desmosome regulation and propose that apremilast is protective in pemphigus by stabilizing keratinocyte cohesion.

cell biology↗

bioRxiv2020

Clustering of desmosomal cadherins by desmoplakin is essential for cell-cell adhesion

Desmoplakin (Dp) localizes to desmosomes, linking clusters of desmosomal adhesion molecules to the intermediate filament cytoskeleton. Here, we generated Dp knockout (ko) cell lines of human keratinocytes to study the impact on desmosomal adhesion molecules and desmosome turnover using atomic force microscopy and superresolution imaging. In comparison to ko of another desmosomal component, plakoglobin (Pg), loss of Dp resulted in absence of desmosomes and drastically impaired cell cohesion. In Dp ko, the desmosomal adhesion molecules desmoglein 2 (Dsg2) and desmocollin 3 (Dsc3) were redistributed into small clusters in the cell membrane with no further increase in loss of intercellular adhesion by silencing of Dsg2. This suggests that extradesmosomal cadherins do not significantly contribute to cell cohesion but rather localization within desmosomes is required. Our data outline a crucial role of Dp for both desmosomal molecule clustering and mature desmosome formation and provide novel insights into the regulation of intercellular adhesion.

cell biology↗

bioRxiv2019

The actin binding protein α-adducin modulates desmosomal turnover and plasticity

Intercellular adhesion is essential for tissue integrity and homeostasis. Desmosomes are especially abundant in the epidermis and the myocardium, tissues, which are under constantly changing mechanical stresses. Yet, it is largely unclear whether desmosomal adhesion can be rapidly adapted to changing demands and the mechanisms underlying desmosome turnover are only partially understood. We here show that loss of the actin-binding protein -adducin prevented the ability of cultured keratinocytes or murine epidermis to withstand mechanical stress paralleled with reduced desmosome number. This effect was not caused by decreased levels or impaired adhesive properties of desmosomal molecules but rather by altered desmosome turnover. Mechanistically, reduced cortical actin density in -adducin knockout keratinocytes resulted in increased mobility of the desmosomal adhesion molecule desmoglein 3 (Dsg3) and impaired interactions with E-cadherin, a crucial step in desmosome formation. Accordingly, loss of -adducin prevented increased membrane localization of Dsg3 in response to cyclic stretch or shear stress. Our data demonstrate plasticity of desmosomal molecules in response to mechanical stimuli and unravel a mechanism how the actin cytoskeleton indirectly shapes intercellular adhesion by restricting the mobility of desmosomal molecules.

cell biology↗