Transcriptomic characterization of a human in vitro model of arrhythmogenic cardiomyopathy under topological and mechanical stimuli

Cell junctions play an important role in coordinating intercellular communication and intracellular ultrastructures, with desmosomes representing the mechanical component of such intercellular connections. Mutations to desmosomal component proteins compromise both inter- and intracellular signalling and correlate with severe diseases like arrhythmogenic cardiomyopathy (AC), with pathological phenotypes in tissues subjected to intense mechanical stimuli (skin and heart). Here, we explore the consequences of dysfunctional desmosomes in one line of induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) derived from an AC patient with a homozygous pathogenic mutation in desmosomal component protein plakophilin-2 (PKP2). We specifically aim at investigating the response to mechanical stress in an AC-pathological setting. To this aim, we aligned hiPS-CMs on stretchable patterned substrates to mimic the cardiac functional syncytium and compared transcriptomic profiles of PKP2-mutated hiPS-CMs and healthy controls. AC-CMs display altered transcription towards a pro-fibrotic gene expression program, and concurrent dysregulation of gene sets closely associated with cell-to-cell connections. By integrating the culture substrate with a macroscopic stretching setup able to accurately apply cyclic uniaxial elongation, we show how response to mechanical loads in AC-CMs deviates from the canonical mechanical-stress response observed in healthy-CMs.