Desmoplakin CSM models unravel mechanisms regulating the binding to intermediate filaments and putative therapeutics for cardiocutaneous diseases

Abstract

Arrhythmogenic cardiomyopathy (AC) is a severe heart condition that can be fatal during intense exercise or in pregnant women. It is induced by mutation (e.g. R2834H) of the carboxyterminus tail of desmoplakin (DP CT), but the lack of knowledge on this region limits the discovery of therapeutic compounds. Here, we have created 3D models of DP CT which show the structural effects of AC-inducing mutations as well as the implications of post-translational modifications (PTMs). Our results suggest that, in absence of PTMs, positively charged wildtype DP CT likely folds back onto negatively-charged plectin repeat 14 of nearby plakin repeat domain C (PRD C) contributing to the recruitment of intermediate filaments (IFs). When phosphorylated and methylated, negatively-charged wildtype DP CT would then fold back onto positively-charged plectin repeat 17 of PRD C, promoting the repulsion of intermediate filaments (IFs). However, by preventing PTMs, the R2834H mutation would lead to the formation of a cytoplasmic mutant desmoplakin with a constitutively positive DP CT tail that would be aberrantly recruited by cytoplasmic IFs instead of desmosomes, potentially weakening cell-cell contacts and promoting AC. Virtual screening of FDA-approved drug libraries identified several promising drug candidates for the treatment of cardiocutaneous diseases through drug repurposing.