Key result
Adrenergic signaling, PKC activation, and p38MAPK inhibition enhanced basal cardiomyocyte adhesion via ERK1/2 and induced hyperadhesion, mechanisms partially offset in plakoglobin-deficient mice.
Why the study?
Arrhythmogenic cardiomyopathy therapy is limited because the mechanisms by which desmosomal components control cardiomyocyte function are largely unknown.
Cardiomyocyte adhesion can be stabilized by adrenergic and PKC signaling, offering potential new mechanistic targets for treating arrhythmogenic cardiomyopathy.
Arrhythmogenic cardiomyopathy (AC) is a heart disease often caused by mutations in genes coding for desmosomal proteins, including desmoglein-2 (DSG2), plakoglobin (PG), and desmoplakin (DP). Therapy is based on symptoms and limiting arrhythmia, because the mechanisms by which desmosomal components control cardiomyocyte function are largely unknown. A new paradigm could be to stabilize desmosomal cardiomyocyte adhesion and hyperadhesion, which renders desmosomal adhesion independent from Ca2+. Here, we further characterized the mechanisms behind enhanced cardiomyocyte adhesion and hyperadhesion. Dissociation assays performed in HL-1 cells and murine ventricular cardiac slice cultures allowed us to define a set of signaling pathways regulating cardiomyocyte adhesion under basal and hyperadhesive conditions. Adrenergic signaling, activation of PKC, and inhibition of p38MAPK enhanced cardiomyocyte adhesion, referred to as positive adhesiotropy, and induced hyperadhesion. Activation of ERK1/2 paralleled positive adhesiotropy, whereas adrenergic signaling induced PG phosphorylation at S665 under both basal and hyperadhesive conditions. Adrenergic signaling and p38MAPK inhibition recruited DSG2 to cell junctions. In PG-deficient mice with an AC phenotype, only PKC activation and p38MAPK inhibition enhanced cardiomyocyte adhesion. Our results demonstrate that cardiomyocyte adhesion can be stabilized by different signaling mechanisms, which are in part offset in PG-deficient AC.
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Shoykhet et al. (2020) studied Arrhythmogenic cardiomyopathy. Adrenergic signaling, PKC activation, and p38MAPK inhibition vs. Vehicle/Control was evaluated on Cardiomyocyte adhesion (measured by dissociation assays). Adrenergic signaling, PKC activation, and p38MAPK inhibition enhanced basal cardiomyocyte adhesion via ERK1/2 and induced hyperadhesion, mechanisms partially offset in plakoglobin-deficient mice.
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