Biology subjects

Stangner, K.

Publications and source records attributed to Stangner, K..

3 recordsLinked to original sources

bioRxiv2025

Autoantibodies in patients with arrhythmogenic cardiomyopathy activate GSK-3β resulting in a loss of cardiomyocyte cohesion

Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiac desmosome disease, as more than 50% of affected patients carry pathogenic variants in desmosome protein-coding genes., In this study, we focused on the role and mechanisms of pathogenic and non-pathogenic autoantibodies against intercalated disc (ICD) proteins such as desmoglein2 (DSG2) in ACM patients, healthy relatives and murine ACM models. IgG fractions from ACM patients and healthy relatives, but not murine ACM model-derived or healthy control IgGs, revealed positive ICD staining. Antibodies reducing the loss of cardiomyocyte cohesion were found in three out of five ACM patients. Pathogenic autoantibodies, bound to DSG2 in hiPSC-CMs, cleaved DSG2 and reduced DSG2 interaction at the molecular level. We investigated GSK-3{beta} contribution to the loss of cardiomyocyte cohesion and observed that GSK-3{beta} reduced baseline cardiomyocyte cohesion in cultured cardiomyocytes and cardiac slices. Pathogenic ACM-IgGs activated GSK-3{beta} upstream of p38MAPK, leading to phosphorylation and junctional loss of {beta}-catenin. GSK-3{beta} inhibition rescued the loss of cell cohesion induced by ACM-IgGs in ACM hiPSC-CMs. Pathogenic autoantibodies targeting DSG2 are present in ACM patients and impair cardiomyocyte cohesion in a GSK-3{beta}-dependent manner. In contrast, autoantibodies are absent in murine ACM models and are non-pathogenic in some patients, healthy relatives.

cell biology↗

bioRxiv2025

Apremilast improves cardiomyocyte cohesion and arrhythmia in different models for arrhythmogenic cardiomyopathy

BackgroundArrhythmogenic cardiomyopathy (ACM) is a genetically inherited desmosome heart disease leading to life-threatening arrhythmias and sudden cardiac death. Currently, ACM treatment paradigms are merely symptom targeting. Recently, apremilast was shown to stabilize keratinocyte adhesion in the desmosomal disease pemphigus vulgaris. Therefore, this study investigated whether apremilast can be a therapeutic option for ACM. MethodsHuman induced pluripotent stem cells from a healthy control (hiPSC) and an ACM index patient (ACM-hiPSC) carrying a heterozygous desmoplakin (DSP) gene mutation (c.2854G>T, p.Glu952Ter), confirmed by whole exome sequencing (WES), were established. Cyclic-AMP ELISA, dissociation assay, immunostaining, and Western blotting analyses were performed in human iPSC-derived cardiomyocytes (hiPSC-CMs), murine HL-1 cardiomyocytes, and cardiac slices derived from wild-type (WT) mice, plakoglobin (PG, Jup) knockout (Jup-/-) (murine ACM model) or PG Serine 665 phosphodeficient (JUP-S665A) mice. Microelectrode array (MEA) analyses in ventricular cardiac slices and Langendorff heart perfusion were performed to analyze heart rate variability and arrhythmia. ResultsACM-hiPSC derived cardiomyocytes (ACM-hiPSC-CMs) revealed a significant loss of cohesion, which was rescued by apremilast. Further, treatment with apremilast strengthened basal cardiomyocyte cohesion in HL-1 cells and WT murine cardiac slices, paralleled by phosphorylation of PG at Serine 665 in human and murine models. In HL-1 cells, apremilast in addition activated ERK1/2, inhibition of which abolished apremilast-enhanced cardiomyocyte cohesion. Further, dissociation assays in slice cultures from JUP-S665A and Jup-/- mice revealed that PG is crucial for apremilast-enhanced cardiomyocyte cohesion. In parallel to enhanced cell adhesion, MEA and Langendorff measurements from WT and Jup-/- mice demonstrated decreased heart rate variability and arrhythmia after apremilast treatment. ConclusionsApremilast improves loss of cardiomyocyte cohesion, enhances localization of DSG2, and reduces arrhythmia in human and murine models of ACM ex vivo and in vitro, providing a novel treatment strategy for ACM by preserving desmosome function. Translational perspectiveThe current therapeutic options for patients with arrhythmogenic cardiomyopathy (ACM) include lifestyle changes, treatment with anti-arrhythmic drugs, catheter ablation, implantable cardiac defibrillators, and ultimately, heart transplantation for patients who are having therapy refractory arrhythmia or developed heart failure. However, lifestyle changes, such as restraining from physical endurance activities and {beta}-blocker therapy, are most used in patients carrying genetic variants coding for proteins of the desmosomal complex. Recent advancements hint that strategies enhancing intracellular cAMP could be beneficial in treating desmosomal diseases and can be effective therapeutics, which would be highly relevant for ACM patients. In this study, we show that apremilast improves loss of cardiomyocyte cohesion, enhances localization of desmosomal proteins, and reduces arrhythmia in both human and murine models of ACM ex vivo and in vitro, providing a novel treatment strategy for ACM by preserving desmosome function.

cell biology↗

bioRxiv2023

Catalytic antibodies in arrhythmogenic cardiomyopathy patients cleave desmoglein 2 and N-cadherin and impair cardiomyocyte cohesion

AimsArrhythmogenic cardiomyopathy (AC) is a severe heart disease predisposing to ventricular arrhythmias and sudden cardiac death caused by mutations affecting intercalated disc (ICD) proteins and aggravated by physical exercise. Recently, autoantibodies targeting ICD proteins, including the desmosomal cadherin desmoglein 2 (DSG2), were reported in AC patients and were considered relevant for disease development and progression, particularly in patients without underlying pathogenic mutations. However, it is unclear at present whether these autoantibodies are pathogenic and by which mechanisms show specificity for DSG2 and thus can be used as a diagnostic tool. Methods and ResultsIgG fractions were purified from 15 AC patients and 4 healthy controls. Immunostainings dissociation assays, atomic force microscopy (AFM), western blot analysis and Triton-X-100 assays were performed utilizing human heart left ventricle tissue, HL-1 cells, and murine cardiac slices. Immunostainings revealed that autoantibodies against ICD proteins are prevalent in AC and most autoantibody fractions have catalytic properties and cleave the ICD adhesion molecules DSG2 and N-cadherin, thereby reducing cadherin interactions as revealed by AFM. Furthermore, most of the AC-IgG fractions causing loss of cardiomyocyte cohesion activated p38MAPK, which is known to contribute to a loss of desmosomal adhesion in different cell types, including cardiomyocytes. In addition, p38MAPK inhibition rescued the loss of cardiomyocyte cohesion induced by AC-IgGs. ConclusionOur study demonstrates that catalytic autoantibodies play a pathogenic role by cleaving ICD cadherins and thereby reducing cardiomyocyte cohesion by a mechanism involving p38MAPK activation. Finally, we conclude that DSG2 cleavage by autoantibodies could be used as a diagnostic tool for AC.

cell biology↗