Abstract Body: Introduction: Loss of function (LoF) variants in desmoplakin (DSP) are the most common cause of left-dominant arrhythmogenic cardiomyopathy (ACM). DSP transduces mechanical force to intercalated disks, and DSP LoF leads to diminished cell-cell adhesion with contractile stress.
Hypothesis: We hypothesized that stabilizing desmosomes via EGFR inhibition could partially rescue adhesion failure due to DSP LoF variants.
Methods: Using induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) models with DSP LoF variants, we generated cardiac muscle bundles (CMBs), which exhibit uniaxial contractions at an approximate physiologic workload (8 kPa substrate). We induced acute contractile stress in CMBs with endothelin-1 (ET-1). CMBs were pre-treated with erlotinib (EGFR inhibitor) or downstream signaling inhibitors (ERK, AKT). Adhesion failure was monitored via live-cell imaging. We quantified DSP membrane localization using immunofluorescence and p-ERK/p-AKT signaling via AlphaLISA. RNA-Seq and mass spec-based proteomics were performed.
Results: Erlotinib improved adhesion failure by 34% (<0.0001) and decreased the average area of tissue disruption by 18% (p<0.0001) in DSP LoF CMBs. This mechanical rescue was accompanied by a 3.6-fold increase (p <0.0001) in DSP sarcolemmal co-localization, suggesting enhanced desmosome assembly. Erlotinib reduced the p-ERK/total-ERK ratio (36%±8.2, p= 0.008). Targeted ERK inhibition modestly improved tissue disruption (13.6% improvement, p= 0.0002) while targeted AKT inhibition caused widespread tissue lethality. Omics analysis indicated significant upregulation of TGF-β signaling pathway and Col1A1 in DSP LoF compared to control tissues, which was partially rescued by erlotinib.
Conclusion: The EGFR/ERK axis is a potent modulator of desmosomal mechanical stability. EGFR inhibition partially rescues DSP LoF adhesion failure as a potential upstream therapeutic strategy.