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Brenda Gerull - One of the best experts on this subject based on the ideXlab platform.
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transgenic mice overexpressing DSC2 develop biventricular cardiomyopathy associated with fibrosis and necrosis
Canadian Journal of Cardiology, 2015Co-Authors: Andreas Brodehl, L Garnett, C Diao, Kristina Martens, Anders Nygren, Y X Chen, Darrell D Belke, Brenda GerullAbstract:BACKGROUND: Arrhythmogenic cardiomyopathy (AC) is an inherited heart disease associated with arrhythmias and right or biventricular dilation often leading to sudden cardiac death or heart failure. AC is mainly caused by mutations in five genes encoding cardiac desmosomal proteins (JUP, DSP, PKP2, DSG2 and DSC2). The cardiac desmosomes are cellcell junctions coupling the cardiomyocytes. Desmocollin-2 (DSC2) and desmoglein-2 (DSG2) are members of the cadherin family and mediate the Ca2+-dependent cardiomyocyte adhesion. Plakophilin-2 (PKP2), plakoglobin (JUP) and desmoplakin (DSP) are linker proteins connecting the cytoplasmic domains of these cadherins to the intermediate filament system. However, the molecular and cellular pathomechanisms induced by mutations in these genes are widely unknown limiting the efficient development of therapeutic therapies. PURPOSE: So far, no DSC2 mouse model mimicking an AC is described. The aim of this project was therefore to establish and characterize an adequate mouse model to understand the underlying pathomechanisms in vivo and ex vivo. METHODS: We developed and characterized a transgenic mouse model with a cardiac-specific overexpression of DSC2. Echocardiography was used to characterize the heart function and (immuno)histology was used to characterize the structural defects the transgenic mice. Western-blot analysis and qRTPCR was used to characterize the molecular expression changes of the desmosomal genes. RESULTS: Transgenic mice with a cardiac specific overexpression of DSC2 developed a severe cardiomyopathy shortly after birth with significantly reduced fractional shortening and ejection fractions. Time-dependent functional analysis revealed that the phenotype is deteriorating leading to heart failure and cardiac death after 12 weeks. The myocardial tissue of the septum as well as of both ventricular walls was significantly replaced by fibrosis and was associated with calcification and necrosis in these areas. CONCLUSION: The established cardiac specific overexpressing DSC2 mice are viable but develop a progressive biventricular cardiomyopathy mimicking the clinical phenotype of patients with arrhythmogenic cardiomyopathy. In the future this novel mouse model could contribute to further understanding of the molecular and cellular pathomechanisms leading to AC. 129 INCREASED CARDIAC MITOCHONDRIAL-DERIVED VESICLE FORMATION IN RESPONSE TO ACUTE STRESS AND DOXORUBICIN-INDUCED CARDIOTOXICITY
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Abstract 1051: Mutant Desmocollin-2 Causes Arrhythmogenic Right Ventricular Cardiomyopathy
Circulation, 2006Co-Authors: Arnd Heuser, Eva Plovie, Patrick T. Ellinor, Katja S. Grossmann, Sabine Sasse-klaassen, Ludwig Thierfelder, Calum A. Macrae, Brenda GerullAbstract:Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetically heterogeneous heart muscle disease characterized by progressive fibrous-fatty replacement of right ventricular myocardium and an increased risk of sudden cardiac death. Mutations in desmosomal plaque proteins have been previously described to cause both autosomal dominant and autosomal recessive forms of ARVC. Therefore we hypothesized that mutations in the cardiac desmosomal cadherin, desmocollin-2 (DSC2) might cause ARVC in humans. We identified an A to G transition that affects the highly conserved 3′ splice acceptor site of intron 5 (IVS5–2A > G) of the DSC2 gene in a patient with ARVC diagnosed by the proposed Task force criteria. This splice acceptor site mutation in DSC2 led to the use of a cryptic splice acceptor site with a deletion of the highly conserved cell adhesion recognition (CAR) sequence and a creation of a downstream premature termination codon (PTC). Quantitative analysis of cardiac DSC2 expression in patient specimens revealed a marked reduction in the abundance (3%) of the truncated mutant allele at mRNA level, supporting possible nonsense-mediated mRNA decay. At protein level the wildype DSC2 expression was reduced when compared with control myocardium, suggesting that haploin-sufficiency may contribute to the disease mechanism for this mutation. To further evaluate the consequences of reduced cardiac DSC2 we cloned the zebrafish DSC2 gene, and studied zebrafish embryos with antisense morpholino knockdown of DSC2. These DSC2 knockdown embryos developed morphologic and hemodynamic features of myocardial contractile failure. Ultrastructural analyses of morphant hearts reveal reduced desmosomal plaque area and consistent loss of the desmosome extracellular electron-dense midlines. We conclude that DSC2 mutations can cause ARVC and demonstrate for the first time in vivo that physiologic levels of DSC2 are crucial for normal cardiac desmosome formation, early cardiac morphogenesis and normal cardiac function. The implication of desmosomal cadherin DSC2 as a new disease gene also extends the concept of ARVC as primarily a disorder of the cardiac desmosome.
Guang-hui Yi - One of the best experts on this subject based on the ideXlab platform.
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Oxidized low-density lipoprotein attenuated desmoglein 1 and desmocollin 2 expression via LOX-1/Ca2+/PKC-β signal in human umbilical vein endothelial cells
Biochemical and Biophysical Research Communications, 2015Co-Authors: Yuan-bin Li, Qing-hai Zhang, Zhuang Chen, Zhi-jun He, Guang-hui YiAbstract:Abstract Numerous studies have reported the presence of oxidized LDL (ox-LDL) and expression of its lectin-like receptor, LOX-1, have been shown in atherosclerotic regions. The present study aims to investigate the effects of ox-LDL on expression of desmoglein 1 (DSG1) and desmocollin 2 (DSC2) in endothelial cells, and to explore the role of LOX-1 mediated signal in the permeability injury associated with DSG1 and DSC2 disruption induced by oxidized lipoprotein. RT-PCR and Western blotting were applied to determine the mRNA and protein expression levels of DSG1 and DSC2 in human umbilical vein endothelial cells (HUVECs) respectively. Immunoreactivities of DSG1 and DSC2 were detected by laser scanning confocal microscope (LSCM). HUVEC monolayers permeability was evaluated by FITC-labeled LDL in transwell assay system. The possible signal was assessed using in vitro blocking LOX-1 or Ca2+ channel or PKC. The DSG1 and DSC2 expression were decreased by ox-LDL in concentration- and time-dependent manner. The effects of ox-LDL were mediated by its endothelial receptor, LOX-1. In parallel experiments, ox-LDL increased the influx of extracellular calcium, activation of protein kinase C (PKC) and permeability to LDL, which was inhibited by the LOX-1blocking antibody (10 μg/ml), Ca2+ channel blocker (Diltiazem, 50 μmol/L) and PKC-β inhibitor (hispidin, 4 μmol/L). These results suggested that ox-LDL-induced decrease in DSG1 and DSC2 expression and monolayer barrier injury via calcium uptake and PKC-β activation following up-regulation of LOX-1 is one of the mechanisms of inducing greater permeability in HUVECs.
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Oxidized low-density lipoprotein attenuated desmoglein 1 and desmocollin 2 expression via LOX-1/Ca(2+)/PKC-β signal in human umbilical vein endothelial cells.
Biochemical and biophysical research communications, 2015Co-Authors: Yuan-bin Li, Qing-hai Zhang, Zhuang Chen, Zhi-jun He, Guang-hui YiAbstract:Numerous studies have reported the presence of oxidized LDL (ox-LDL) and expression of its lectin-like receptor, LOX-1, have been shown in atherosclerotic regions. The present study aims to investigate the effects of ox-LDL on expression of desmoglein 1 (DSG1) and desmocollin 2 (DSC2) in endothelial cells, and to explore the role of LOX-1 mediated signal in the permeability injury associated with DSG1 and DSC2 disruption induced by oxidized lipoprotein. RT-PCR and Western blotting were applied to determine the mRNA and protein expression levels of DSG1 and DSC2 in human umbilical vein endothelial cells (HUVECs) respectively. Immunoreactivities of DSG1 and DSC2 were detected by laser scanning confocal microscope (LSCM). HUVEC monolayers permeability was evaluated by FITC-labeled LDL in transwell assay system. The possible signal was assessed using in vitro blocking LOX-1 or Ca(2+) channel or PKC. The DSG1 and DSC2 expression were decreased by ox-LDL in concentration- and time-dependent manner. The effects of ox-LDL were mediated by its endothelial receptor, LOX-1. In parallel experiments, ox-LDL increased the influx of extracellular calcium, activation of protein kinase C (PKC) and permeability to LDL, which was inhibited by the LOX-1blocking antibody (10 μg/ml), Ca(2+) channel blocker (Diltiazem, 50 μmol/L) and PKC-β inhibitor (hispidin, 4 μmol/L). These results suggested that ox-LDL-induced decrease in DSG1 and DSC2 expression and monolayer barrier injury via calcium uptake and PKC-β activation following up-regulation of LOX-1 is one of the mechanisms of inducing greater permeability in HUVECs.
Tommaso Mazza - One of the best experts on this subject based on the ideXlab platform.
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sudden death in mild hypertrophic cardiomyopathy with compound dsg2 DSC2 myh6 mutations revisiting phenotype after genetic assessment in a master runner athlete
Journal of Electrocardiology, 2019Co-Authors: Stefano Castellana, Sandra Mastroianno, Pietro Palumbo, Orazio Palumbo, Tommaso Biagini, Maria Pia Leone, Giovanni De Luca, Domenico Potenza, Cesare Amico, Tommaso MazzaAbstract:Abstract Cardiomyopathies represent a well-known cause of heart failure and sudden death. Although cardiomyopathies are generally categorized in distinct nosographic entities, characterized by single gene-to-disease causal relationships, recently, oligogenic mutations have also been associated to relevant cardiac clinical features. We report the case of a master athlete carrying trigenic mutations in desmoglein-2 ( DSG2 ), desmocollin-2 ( DSC2 ) and heavy chain myosin 6 ( MYH6 ), which determine a mild hypertrophic phenotype associated both to ventricular tachyarrhythmias and atrio-ventricular block. We discuss the differential diagnosis and prognostic approach in patient affected by complex cardiomyopathy phenotype, along with the importance of sport restriction and sudden death prevention.
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Sudden death in mild hypertrophic cardiomyopathy with compound DSG2/DSC2/MYH6 mutations: Revisiting phenotype after genetic assessment in a master runner athlete
Journal of Electrocardiology, 2019Co-Authors: Stefano Castellana, Sandra Mastroianno, Pietro Palumbo, Orazio Palumbo, Tommaso Biagini, Maria Pia Leone, Giovanni De Luca, Domenico Potenza, Cesare Amico, Tommaso MazzaAbstract:Abstract Cardiomyopathies represent a well-known cause of heart failure and sudden death. Although cardiomyopathies are generally categorized in distinct nosographic entities, characterized by single gene-to-disease causal relationships, recently, oligogenic mutations have also been associated to relevant cardiac clinical features. We report the case of a master athlete carrying trigenic mutations in desmoglein-2 ( DSG2 ), desmocollin-2 ( DSC2 ) and heavy chain myosin 6 ( MYH6 ), which determine a mild hypertrophic phenotype associated both to ventricular tachyarrhythmias and atrio-ventricular block. We discuss the differential diagnosis and prognostic approach in patient affected by complex cardiomyopathy phenotype, along with the importance of sport restriction and sudden death prevention.
Youfang Zhang - One of the best experts on this subject based on the ideXlab platform.
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A non-canonical role for desmoglein-2 in endothelial cells: implications for neoangiogenesis
Angiogenesis, 2016Co-Authors: Lisa M. Ebert, M. Zahied Johan, Michaelia P. Cockshell, Kate A. Parham, Kelly L. Betterman, Paceman Szeto, Samantha Boyle, Lokugan Silva, Angela Peng, Youfang ZhangAbstract:Desmogleins (DSG) are a family of cadherin adhesion proteins that were first identified in desmosomes and provide cardiomyocytes and epithelial cells with the junctional stability to tolerate mechanical stress. However, one member of this family, DSG2, is emerging as a protein with additional biological functions on a broader range of cells. Here we reveal that DSG2 is expressed by non-desmosome-forming human endothelial progenitor cells as well as their mature counterparts [endothelial cells (ECs)] in human tissue from healthy individuals and cancer patients. Analysis of normal blood and bone marrow showed that DSG2 is also expressed by CD34^+CD45^dim hematopoietic progenitor cells. An inability to detect other desmosomal components, i.e., DSG1, DSG3 and desmocollin (DSC)2/3, on these cells supports a solitary role for DSG2 outside of desmosomes. Functionally, we show that CD34^+CD45^dimDSG2^+ progenitor cells are multi-potent and pro-angiogenic in vitro. Using a ‘knockout-first’ approach, we generated a Dsg2 loss-of-function strain of mice ( Dsg2 ^lo/lo) and observed that, in response to reduced levels of Dsg2 : (i) CD31^+ ECs in the pancreas are hypertrophic and exhibit altered morphology, (ii) bone marrow-derived endothelial colony formation is impaired, (iii) ex vivo vascular sprouting from aortic rings is reduced, and (iv) vessel formation in vitro and in vivo is attenuated. Finally, knockdown of DSG2 in a human bone marrow EC line reveals a reduction in an in vitro angiogenesis assay as well as relocalisation of actin and VE-cadherin away from the cell junctions, reduced cell–cell adhesion and increased invasive properties by these cells. In summary, we have identified DSG2 expression in distinct progenitor cell subpopulations and show that, independent from its classical function as a component of desmosomes, this cadherin also plays a critical role in the vasculature.
Andreas Brodehl - One of the best experts on this subject based on the ideXlab platform.
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a homozygous DSC2 deletion associated with arrhythmogenic cardiomyopathy is caused by uniparental isodisomy
Journal of Molecular and Cellular Cardiology, 2020Co-Authors: Andreas Brodehl, Caroline Stanasiuk, Jurgen Weiss, Jana Davina Debus, Barbel Klauke, Marcus Andre Deutsch, Hans Ebbinghaus, Anna Gartner, Jens Tiesmeier, T K LaserAbstract:Abstract Aims We aimed to unravel the genetic, molecular and cellular pathomechanisms of DSC2 truncation variants leading to arrhythmogenic cardiomyopathy (ACM). Methods and results We report a homozygous 4-bp DSC2 deletion variant c.1913_1916delAGAA, p.Q638LfsX647hom causing a frameshift carried by an ACM patient. Whole exome sequencing and comparative genomic hybridization analysis support a loss of heterozygosity in a large segment of chromosome 18 indicating segmental interstitial uniparental isodisomy (UPD). Ultrastructural analysis of the explanted myocardium from a mutation carrier using transmission electron microscopy revealed a partially widening of the intercalated disc. Using qRT-PCR we demonstrated that DSC2 mRNA expression was substantially decreased in the explanted myocardial tissue of the homozygous carrier compared to controls. Western blot analysis revealed absence of both full-length desmocollin-2 isoforms. Only a weak expression of the truncated form of desmocollin-2 was detectable. Immunohistochemistry showed that the truncated form of desmocollin-2 did not localize at the intercalated discs. In vitro, transfection experiments using induced pluripotent stem cell derived cardiomyocytes and HT-1080 cells demonstrated an obvious absence of the mutant truncated desmocollin-2 at the plasma membrane. Immunoprecipitation in combination with fluorescence measurements and Western blot analyses revealed an abnormal secretion of the truncated desmocollin-2. Conclusion In summary, we unraveled segmental UPD as the likely genetic reason for a small homozygous DSC2 deletion. We conclude that a combination of nonsense mediated mRNA decay and extracellular secretion is involved in DSC2 related ACM.
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Incorporation of desmocollin‐2 into the plasma membrane requires N‐glycosylation at multiple sites
FEBS Open Bio, 2019Co-Authors: Andreas Brodehl, Caroline Stanasiuk, Dario Anselmetti, Jan Gummert, Hendrik MiltingAbstract:Desmocollin‐2 (DSC2) is a desmosomal protein of the cadherin family. Desmosomes are multiprotein complexes, which are involved in cell adhesion of cardiomyocytes and of keratinocytes. The molecular structure of the complete extracellular domain (ECD) of DSC2 was recently described, revealing three disulfide bridges, four N‐glycosylation sites, and four O‐mannosylation sites. However, the functional relevance of these post‐translational modifications for the protein trafficking of DSC2 to the plasma membrane is still unknown. Here, we generated a set of DSC2 mutants, in which we systematically exchanged all N‐glycosylation sites, O‐mannosylation sites, and disulfide bridges within the ECD and investigated the resulting subcellular localization by confocal laser scanning microscopy. Of note, all single and double N‐glycosylation‐ deficient mutants were efficiently incorporated into the plasma membrane, indicating that the absence of these glycosylation sites has a minor effect on the protein trafficking of DSC2. However, the exchange of multiple N‐glycosylation sites resulted in intracellular accumulation. Colocalization analysis using cell compartment trackers revealed that N‐glycosylation‐ deficient DSC2 mutants were retained within the Golgi apparatus. In contrast, elimination of the four O‐mannosylation sites or the disulfide bridges in the ECD has no obvious effect on the intracellular protein processing of DSC2. These experiments underscore the importance of N‐glycosylation at multiple sites of DSC2 for efficient intracellular transport to the plasma membrane.
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transgenic mice overexpressing DSC2 develop biventricular cardiomyopathy associated with fibrosis and necrosis
Canadian Journal of Cardiology, 2015Co-Authors: Andreas Brodehl, L Garnett, C Diao, Kristina Martens, Anders Nygren, Y X Chen, Darrell D Belke, Brenda GerullAbstract:BACKGROUND: Arrhythmogenic cardiomyopathy (AC) is an inherited heart disease associated with arrhythmias and right or biventricular dilation often leading to sudden cardiac death or heart failure. AC is mainly caused by mutations in five genes encoding cardiac desmosomal proteins (JUP, DSP, PKP2, DSG2 and DSC2). The cardiac desmosomes are cellcell junctions coupling the cardiomyocytes. Desmocollin-2 (DSC2) and desmoglein-2 (DSG2) are members of the cadherin family and mediate the Ca2+-dependent cardiomyocyte adhesion. Plakophilin-2 (PKP2), plakoglobin (JUP) and desmoplakin (DSP) are linker proteins connecting the cytoplasmic domains of these cadherins to the intermediate filament system. However, the molecular and cellular pathomechanisms induced by mutations in these genes are widely unknown limiting the efficient development of therapeutic therapies. PURPOSE: So far, no DSC2 mouse model mimicking an AC is described. The aim of this project was therefore to establish and characterize an adequate mouse model to understand the underlying pathomechanisms in vivo and ex vivo. METHODS: We developed and characterized a transgenic mouse model with a cardiac-specific overexpression of DSC2. Echocardiography was used to characterize the heart function and (immuno)histology was used to characterize the structural defects the transgenic mice. Western-blot analysis and qRTPCR was used to characterize the molecular expression changes of the desmosomal genes. RESULTS: Transgenic mice with a cardiac specific overexpression of DSC2 developed a severe cardiomyopathy shortly after birth with significantly reduced fractional shortening and ejection fractions. Time-dependent functional analysis revealed that the phenotype is deteriorating leading to heart failure and cardiac death after 12 weeks. The myocardial tissue of the septum as well as of both ventricular walls was significantly replaced by fibrosis and was associated with calcification and necrosis in these areas. CONCLUSION: The established cardiac specific overexpressing DSC2 mice are viable but develop a progressive biventricular cardiomyopathy mimicking the clinical phenotype of patients with arrhythmogenic cardiomyopathy. In the future this novel mouse model could contribute to further understanding of the molecular and cellular pathomechanisms leading to AC. 129 INCREASED CARDIAC MITOCHONDRIAL-DERIVED VESICLE FORMATION IN RESPONSE TO ACUTE STRESS AND DOXORUBICIN-INDUCED CARDIOTOXICITY
