Mislocalization of Adherens Junction- Associated Proteins in a Patient with Darier Disease

Abstract

Darier disease (DD) is an autosomal dominant keratinizing genodermatosis that manifests clinically with red-brown pruritic papules in a seborrheic distribution often in association with palmoplantar pits and dystrophic nail changes. It is caused by mutation in ATP2A2 which encodes a sarco/endoplasmic reticulum calcium ATPase isoform 2 (SERCA2) pump that regulates calcium flux. Consequent alteration of intracellular calcium homeostasis is thought to impair trafficking of cellular adhesion proteins and to lead to aberrant keratinocyte differentiation, contributing to the characteristic histopathologic features of acantholysis and dyskeratosis in DD, though the precise mechanisms are incompletely understood. Previous studies have identified defective localization of desmosomal attachment proteins in skin biopsies and cultured keratinocytes from DD patients, but reports of effects on adherens junction proteins (including calcium-dependent E-cadherin) are conflicting. Here we describe a case of DD presenting with characteristic clinical and histologic features in which we performed immunofluorescence staining of four adherens junction-associated proteins (E-cadherin, α-catenin, β-catenin, and vinculin). In lesional (acantholytic) DD skin, we identified loss of distinctive bright membranous staining that was present at the periphery of keratinocytes throughout the epidermis in the healthy skin of a matched donor. Perilesional (non-acantholytic) portions of DD skin partially recapitulated the normal phenotype. Our findings support a role for SERCA2 dysfunction in impaired assembly of adherens junctions, which together with defective desmosomes contribute to acantholysis in DD.