TY - JOUR A1 - Brodehl, Andreas A1 - Meshkov, Alexey A1 - Myasnikov, Roman A1 - Kiseleva, Anna A1 - Kulikova, Olga A1 - Klauke, Bärbel A1 - Sotnikova, Evgeniia A1 - Stanasiuk, Caroline A1 - Divashuk, Mikhail A1 - Pohl, Greta Marie A1 - Kudryavtseva, Maria A1 - Klingel, Karin A1 - Gerull, Brenda A1 - Zharikova, Anastasia A1 - Gummert, Jan A1 - Koretskiy, Sergey A1 - Schubert, Stephan A1 - Mershina, Elena A1 - Gärtner, Anna A1 - Pilus, Polina A1 - Laser, Kai Thorsten A1 - Sinitsyn, Valentin A1 - Boytsov, Sergey A1 - Drapkina, Oxana A1 - Milting, Hendrik T1 - Hemi- and homozygous loss-of-function mutations in DSG2 (desmoglein-2) cause recessive arrhythmogenic cardiomyopathy with an early onset JF - International Journal of Molecular Sciences N2 - About 50% of patients with arrhythmogenic cardiomyopathy (ACM) carry a pathogenic or likely pathogenic mutation in the desmosomal genes. However, there is a significant number of patients without positive familial anamnesis. Therefore, the molecular reasons for ACM in these patients are frequently unknown and a genetic contribution might be underestimated. Here, we used a next-generation sequencing (NGS) approach and in addition single nucleotide polymor-phism (SNP) arrays for the genetic analysis of two independent index patients without familial medical history. Of note, this genetic strategy revealed a homozygous splice site mutation (DSG2–c.378+1G>T) in the first patient and a nonsense mutation (DSG2–p.L772X) in combination with a large deletion in DSG2 in the second one. In conclusion, a recessive inheritance pattern is likely for both cases, which might contribute to the hidden medical history in both families. This is the first report about these novel loss-of-function mutations in DSG2 that have not been previously identi-fied. Therefore, we suggest performing deep genetic analyses using NGS in combination with SNP arrays also for ACM index patients without obvious familial medical history. In the future, this finding might has relevance for the genetic counseling of similar cases. KW - desmoglein-2 KW - desmocollin-2 KW - DSG2 KW - DSC2 KW - ARVC KW - ACM KW - LVNC KW - cardiomyopathy KW - desmosomes KW - desmin Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-285279 SN - 1422-0067 VL - 22 IS - 7 ER - TY - THES A1 - Hartleb, Annika T1 - Auswirkungen eines Tandem-Peptids auf den intrazellulären Kalziumhaushalt und Arrhythmien von humanen iPS-Kardiomyozyten mit Mutationen in desmosomalen Proteinen T1 - Effects of a tandem peptide on intracellular calcium cycling and arrhythmias of human iPSC cardiomyocytes with mutations in desmosomal proteins N2 - Die arrhythmogene Kardiomyopathie (ACM) ist eine Herzmuskelerkrankung, die durch den fett- und bindegewebigen Umbau von Herzmuskelgewebe charakterisiert ist. Klinisch treten häufig ventrikuläre Herzrhythmusstörungen auf, teilweise bis hin zum plötzlichen Herztod. ACM ist eine genetisch bedingte Erkrankung, die durch Mutationen in desmosomalen Proteinen, wie Plakophilin-2 (PKP2) und Desmoglein-2 (DSG2), entsteht. Die molekularen Mechanismen sind nur teilweise verstanden und aktuell gibt es keine spezifischen Therapiemöglichkeiten. Ziel der Arbeit war es, die therapeutische Wirkung eines DSG2-spezifischen Tandem-Peptids (TP) durch desmosomale Stabilisierung an humanen Kardiomyozyten (KM) in einem ACM-Modell zu untersuchen. KM wurden aus humanen induzierten pluripotenten Stammzellen (hiPS) einer PKP2-Knockout- (PKP2-KO), DSG2-Knockout- (DSG2-KO) und deren isogener Kontrollzelllinie differenziert. Zunächst wurden verschiedene Methoden der beschleunigten Zellreifung getestet. Dann wurden die PKP2- und DSG2-KO-KM anhand von intrazellulären Kalzium-Messungen und Arrhythmie-Analysen phänotypisch charakterisiert. Letztlich wurde die Wirkung des TPs, das an die DSG2 der geschwächten Zellbindungen von PKP2-KO-KM binden sollte, im Vergleich zu entsprechenden Kontrollen untersucht. Die Ergebnisse zeigen, dass mit der Matrigel-Mattress-Kultivierung und einer Hormonbehandlung elektrisch stimulierbare hiPS-KM mit reifen Eigenschaften hergestellt werden konnten. Der Phänotyp der mutationstragenden PKP2-KO-KM und DSG2-KO-KM zeichnete sich durch erhöhte diastolische Kalzium-Konzentrationen und erniedrigte Kalzium-Amplituden sowie durch beschleunigte Kalzium-Kinetik im Sinne der Relaxationszeiten aus. Weiterhin war bei den PKP2-KO-KM die Häufigkeit der Arrhythmien erhöht, die unter beta-adrenerger Stimulation nachließen. Insgesamt konnte keine eindeutige Wirkung des TPs im ACM-Modell gezeigt werden. Das TP hatte nur auf die diastolischen Kalzium-Konzentrationen der PKP2-KO-KM einen therapeutischen Einfluss, allerdings auch auf DSG2-KO-KM, weshalb der Hinweis auf eine fehlende DSG2-Spezifität des TPs entstand. Schlussfolgernd wurde bestätigt, dass sich reife hiPS-KM mit genetischen Veränderungen als Modell zur Untersuchung der Kalziumhomöostase und von Arrhythmien bei der ACM eignen. Sie können grundsätzlich zum Test von therapeutischen Anwendungen genutzt werden. Die Wirksamkeit und Spezifität des getesteten TPs sollte zukünftig weiter überprüft werden. N2 - Arrhythmogenic cardiomyopathy (ACM) is a myocardial disease characterized by fibrofatty remodeling of myocardial tissue. Clinically, ventricular arrhythmias occur, sometimes leading to sudden cardiac death. ACM is a genetic disease that results from desmosomal mutations, such as plakophilin-2 (PKP2) and desmoglein-2 (DSG2). The molecular mechanisms are only partially understood and currently there are no specific therapeutic options. The aim of this work was to investigate the therapeutic effect of a DSG2-specific tandem peptide (TP) by desmosomal stabilization on human cardiomyocytes (CMs) in an ACM model. CMs were differentiated from human induced pluripotent stem cells (hiPSC) of a PKP2 knockout (PKP2-KO), DSG2 knockout (DSG2-KO) and their isogenic control cell line. First, methods of accelerated cell maturation were tested. Then, PKP2- and DSG2-KO-CMs were phenotypically characterized by using intracellular calcium measurements and arrhythmia analyses. Finally, the effect of a TP designed to bind to DSG2 of the weakened cell binding of PKP2-KO-CMs was examined in comparison with corresponding controls. The results show that matrigel mattress cultivation and hormone treatment were able to produce electrically stimulable hiPSC-CMs with mature characteristics. The phenotype of mutant PKP2-KO-CMs and DSG2-KO-CMs was characterized by increased diastolic calcium concentrations and decreased calcium amplitudes, as well as accelerated calcium kinetics in terms of relaxation times. Furthermore, the frequency of arrhythmias was increased in PKP2-KO-CMs and decreased under beta-adrenergic stimulation. Overall, no clear effect of TP was demonstrated in the ACM model. TP only had a therapeutic effect on diastolic calcium concentrations of PKP2-KO-CMs, although it also had an effect on DSG2-KO-CMs, thus suggesting a lack of DSG2 specificity of TP. In conclusion, it was confirmed that mature hiPSC-CMs with genetic alterations are suitable as a model to study calcium cycling and arrhythmias in ACM. In principle, they can be used to test therapeutic applications. The efficacy and specificity of the tested TP should be further evaluated in the future. KW - Herzmuskelkrankheit KW - Arrhythmie KW - Mutation KW - Calcium KW - Induzierte pluripotente Stammzelle KW - Arrhythmogene Kardiomyopathie KW - Tandem-Peptid KW - PKP2 KW - DSG2 KW - Arrhythmogenic cardiomyopathy KW - desmosomal mutations KW - human induced pluripotent stem cells (hiPSC) KW - calcium cycling KW - arrhythmia KW - tandem peptide Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-316579 ER - TY - JOUR A1 - Hartlieb, Eva A1 - Kempf, Bettina A1 - Partilla, Miriam A1 - Vigh, Balázs A1 - Spindler, Volker A1 - Waschke, Jens T1 - Desmoglein 2 Is Less Important than Desmoglein 3 for Keratinocyte Cohesion JF - PLoS ONE N2 - Desmosomes provide intercellular adhesive strength required for integrity of epithelial and some non-epithelial tissues. Within the epidermis, the cadherin-type adhesion molecules desmoglein (Dsg) 1-4 and desmocollin (Dsc) 1-3 build the adhesive core of desmosomes. In keratinocytes, several isoforms of these proteins are co-expressed. However, the contribution of specific isoforms to overall cell cohesion is unclear. Therefore, in this study we investigated the roles of Dsg2 and Dsg3, the latter of which is known to be essential for keratinocyte adhesion based on its autoantibody-induced loss of function in the autoimmune blistering skin disease pemphigus vulgaris (PV). The pathogenic PV antibody AK23, targeting the Dsg3 adhesive domain, led to profound loss of cell cohesion in human keratinocytes as revealed by the dispase-based dissociation assays. In contrast, an antibody against Dsg2 had no effect on cell cohesion although the Dsg2 antibody was demonstrated to interfere with Dsg2 transinteraction by single molecule atomic force microscopy and was effective to reduce cell cohesion in intestinal epithelial Caco-2 cells which express Dsg2 as the only Dsg isoform. To substantiate these findings, siRNA-mediated silencing of Dsg2 or Dsg3 was performed in keratinocytes. In contrast to Dsg3-depleted cells, Dsg2 knockdown reduced cell cohesion only under conditions of increased shear. These experiments indicate that specific desmosomal cadherins contribute differently to keratinocyte cohesion and that Dsg2 compared to Dsg3 is less important in this context. KW - expression KW - inhibition KW - DSG2 KW - cell adhesion KW - desmosomal cadherins KW - pemphigus vulgaris KW - phenotype KW - mice KW - transinteraction KW - reorganization Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-131192 VL - 8 IS - 1 ER -