Transcriptomic characterization of a human in vitro model of arrhythmogenic cardiomyopathy under topological and mechanical stimuli
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ABSTRACT: Cell junctions play an important role in coordinating intercellular communication and intracellular ultrastructures, with desmosomes representing the mechanical component of such intercellular connections. Mutations to desmosomal component proteins compromise both inter- and intracellular signalling and correlate with severe diseases like arrhythmogenic cardiomyopathy (AC), with pathological phenotypes in tissues subjected to intense mechanical stimuli (skin and heart). Here, we explore the consequences of dysfunctional desmosomes in one line of induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) derived from an AC patient with a homozygous pathogenic mutation in desmosomal component protein plakophilin-2 (PKP2). We specifically aim at investigating the response to mechanical stress in an AC-pathological setting. To this aim, we aligned hiPS-CMs on stretchable patterned substrates to mimic the cardiac functional syncytium and compared transcriptomic profiles of PKP2-mutated hiPS-CMs and healthy controls. AC-CMs display altered transcription towards a pro-fibrotic gene expression program, and concurrent dysregulation of gene sets closely associated with cell-to-cell connections. By integrating the culture substrate with a macroscopic stretching setup able to accurately apply cyclic uniaxial elongation, we show how response to mechanical loads in AC-CMs deviates from the canonical mechanical-stress response observed in healthy-CMs.
Project description:Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a familial cardiac disease associated with ventricular arrhythmias and an increased risk of sudden cardiac death. Currently, there are no approved treatments that address the underlying genetic cause of this disease, representing a significant unmet need. Mutations in Plakophilin-2 (PKP2), encoding a desmosomal protein, account for approximately 40% of ARVC cases and result in reduced gene expression. Methods: Our goal is to examine the feasibility and the efficacy of adeno-associated virus 9 (AAV9)-mediated restoration of PKP2 expression in a cardiac specific knock-out mouse model of Pkp2. Results: We show that a single dose of AAV9:PKP2 gene delivery prevents disease development before the onset of cardiomyopathy and attenuates disease progression after overt cardiomyopathy. Restoration of PKP2 expression leads to a significant extension of lifespan by restoring cellular structures of desmosomes and gap junctions, preventing or halting decline in left ventricular ejection fraction, preventing or reversing dilation of the right ventricle, ameliorating ventricular arrhythmia event frequency and severity, and preventing adverse fibrotic remodeling. RNA sequencing analyses show that restoration of PKP2 expression leads to highly coordinated and durable correction of PKP2-associated transcriptional networks beyond desmosomes, revealing a broad spectrum of biological perturbances behind ARVC disease etiology. Conclusions: We identify fundamental mechanisms of PKP2-associated ARVC beyond disruption of desmosome function. The observed PKP2 dose-function relationship indicates that cardiac-selective AAV9:PKP2 gene therapy may be a promising therapeutic approach to treat ARVC patients with PKP2 mutations.
Project description:Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a familial cardiac disease associated with ventricular arrhythmias and an increased risk of sudden cardiac death. Currently, there are no approved treatments that address the underlying genetic cause of this disease, representing a significant unmet need. Mutations in Plakophilin-2 (PKP2), encoding a desmosomal protein, account for approximately 40% of ARVC cases and result in reduced gene expression. Methods: Our goal is to examine the feasibility and the efficacy of adeno-associated virus 9 (AAV9)-mediated restoration of PKP2 expression in a cardiac specific knock-out mouse model of Pkp2. Results: We show that a single dose of AAV9:PKP2 gene delivery prevents disease development before the onset of cardiomyopathy and attenuates disease progression after overt cardiomyopathy. Restoration of PKP2 expression leads to a significant extension of lifespan by restoring cellular structures of desmosomes and gap junctions, preventing or halting decline in left ventricular ejection fraction, preventing or reversing dilation of the right ventricle, ameliorating ventricular arrhythmia event frequency and severity, and preventing adverse fibrotic remodeling. RNA sequencing analyses show that restoration of PKP2 expression leads to highly coordinated and durable correction of PKP2-associated transcriptional networks beyond desmosomes, revealing a broad spectrum of biological perturbances behind ARVC disease etiology. Conclusions: We identify fundamental mechanisms of PKP2-associated ARVC beyond disruption of desmosome function. The observed PKP2 dose-function relationship indicates that cardiac-selective AAV9:PKP2 gene therapy may be a promising therapeutic approach to treat ARVC patients with PKP2 mutations.
Project description:Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a familial cardiac disease associated with ventricular arrhythmias and an increased risk of sudden cardiac death. Currently, there are no approved treatments that address the underlying genetic cause of this disease, representing a significant unmet need. Mutations in Plakophilin-2 (PKP2), encoding a desmosomal protein, account for approximately 40% of ARVC cases and result in reduced gene expression. Methods: Our goal is to examine the feasibility and the efficacy of adeno-associated virus 9 (AAV9)-mediated restoration of PKP2 expression in a cardiac specific knock-out mouse model of Pkp2. Results: We show that a single dose of AAV9:PKP2 gene delivery prevents disease development before the onset of cardiomyopathy and attenuates disease progression after overt cardiomyopathy. Restoration of PKP2 expression leads to a significant extension of lifespan by restoring cellular structures of desmosomes and gap junctions, preventing or halting decline in left ventricular ejection fraction, preventing or reversing dilation of the right ventricle, ameliorating ventricular arrhythmia event frequency and severity, and preventing adverse fibrotic remodeling. RNA sequencing analyses show that restoration of PKP2 expression leads to highly coordinated and durable correction of PKP2-associated transcriptional networks beyond desmosomes, revealing a broad spectrum of biological perturbances behind ARVC disease etiology. Conclusions: We identify fundamental mechanisms of PKP2-associated ARVC beyond disruption of desmosome function. The observed PKP2 dose-function relationship indicates that cardiac-selective AAV9:PKP2 gene therapy may be a promising therapeutic approach to treat ARVC patients with PKP2 mutations.
Project description:Desmosomes are multiprotein adhesion complexes that link intermediate filaments to the plasma membrane, ensuring the mechanical integrity of cells across tissues, but how they participate in the wider signalling network to exert their full function is unclear. To investigate this we performed multiplexed proximity biotinylation (BioID). The combined interactomes of the essential desmosomal proteins desmocollin 2a, plakoglobin and plakophilin 2a (Pkp2a) in Madin-Darby canine kidney epithelial cells were mapped and their differences and commonalities characterised as desmosome matured from Ca2+-dependence to the mature, Ca2+-independent, hyper-adhesive state, which predominates in tissues. Results suggest distinct roles of individual desmosomal proteins in linking to cellular signalling pathways that alter substantially when cells change their adhesion state. Moreover, we find support for our dualistic concept of desmosomes in which the properties of Pkp2a differ from those of the other, more stable proteins. The data provide a requisite resource to unravel the nature of desmosomes.
Project description:Arrhythmogenic cardiomyopathy (ACM) is an inherited progressive cardiomyopathy. The pathophysiological events are well understood, yet the underlying molecular mechanisms remain undefined. Here, we created a novel research platform comprising of patient originated hiPSC-derived cardiomyocytes bearing a pathological PKP2 mutation (PKP2 c.2013delC/WT), a novel knock-in murine model carrying the equivalent mutation (Pkp2 c.1755delA/WT), and human explanted ACM hearts, to identify disease driving mechanisms. Pkp2 c.1755delA/WT mice displayed reduced desmosomal and adherens junctions protein levels and protein disarray of the intercalated discs in areas of active fibrotic remodeling. These findings were validated in hiPSC-derived cardiomyocytes and human explanted ACM hearts. Led by proteomics data, we demonstrated that the ubiquitin-proteasome system was responsible for the observed desmosomal protein degradation. The research platform presented here provides a strong scientific basis to identify bona fide pathological processes and will aid in the development of potential therapies for the prevention of ACM disease progression.
Project description:Purpose: To induce hiPS-CMs maturation by using engineering technics, including culturing on the anisotropic pattern, has been widely explored. However, the underlying mechanisms of the benefits driven by the aligned topographic stimuli are still pending. To obtain insights into the underlying molecular pathways/signaling involved in the facilitation of hiPS-CMs maturation driven by specific topographic stimuli, we performed RNA-seq for the hiPS-CMs samples after culturing on the different patterns Methods: hiPS-CMs cultured on the flat bottom 24-well plate (MS-80240; Sumilon)/random nanofiber substrate (NanoECM, 2401; Funakoshi)/aligned nanofiber substrate (NanoAligned, 2402; Funakoshi) for one week. Then the cells were harvested as Flat, Random, Align group samples. Total RNA was extracted using the RNeasy Plus mini kit (740990.250; Takara), the concentration of RNA was measured by using NanoDrop (2000/2000c Spectrophotometers, Thermo Fisher). The Illumina package bcl2fastq software was used for base-calling. The raw reads were mapped to the human reference genome sequences (GRCh38) using TopHat ver. 2.1.1 in combination with Bowtie2 ver. 2.3.4.1 Results: The principal component analysis(PCA) analysis revealed that the hiPS-CMs from flat and random patterns showed the most variance. And the differentially expressed genes (DEGs) were detected with theDESeq2 package, showed that the flat group samples occupied most of the enrichment gene expression. The enriched DEGs termed by Gene Ontology(GO) Biological Process revealed that the upregulated genes in flat group are mainly related to the regulation of cell movement, including extracellular matrix organization, cell adhesion, and cell migration. The well-known cardiac maturation markers such as MYH7 and TNNI3 showed significantly upregulated in align group, as well as cardiac structural(MLC2, TNNT2, GJA1), and calcium handling relevant genes( CASQ2, CAMK2B, CAV3) also showed a higher expression than that of in flat group. The most up-regulated gene sets related pathways in align group include cardiac development and heart morphogenesis, negative regulation of binding, and microtubule-based process. In contrast, the relative down-regulated gene enriched pathways in align group are mostly involved in KRT gene family, which also plays a role in cell movement Conclusions: hiPS-CMs by culturing on the aligned pattern for a short-term have facilitated maturation of hiPS-CMs. The up-regulated gene sets in align group related to regulating cell cycle pathways. The genome-wide expression analysis provided insights into the underlying molecular pathways/signaling involved in the specific topographic stimuli induced maturation of hiPS-CMs
Project description:Arrhythmogenic cardiomyopathy (ACM) is an inherited progressive cardiomyopathy. The pathophysiological events are well understood, yet the underlying molecular mechanisms remain undefined. Here we use patient originated hiPSC-derived cardiomyocytes bearing a pathogenic PKP2 mutation (PKP2 c.2013delC/WT), a corresponding knock-in mouse model carrying the equivalent murine mutation (Pkp2 c.1755delA/WT), and human explanted ACM hearts, to identify disease driving mechanisms. Pkp2 c.1755delA/WT mice over time displayed signs of ACM as observed by cardiac dysfunction and pathological remodeling. At a molecular level these mice showed a reduction in desmosomal and adherens junction proteins as well as disarray of the intercalated discs in areas of active fibrotic remodeling. These findings were validated in the mutant hiPSC-derived cardiomyocytes as well as human explanted ACM hearts, indicating both the conservation and relevance of protein degradation in the pathogenesis of the disease. Led by proteomics data, we demonstrated that the ubiquitin-proteasome system was responsible for the observed desmosomal protein degradation. These findings show the importance of appropriate disease modeling and provide means for therapeutic intervention for the prevention of ACM disease progression.
Project description:Arrhythmogenic cardiomyopathy (ACM) is an inherited progressive cardiomyopathy. The pathophysiological events are well understood, yet the underlying molecular mechanisms remain undefined. Here we use patient originated hiPSC-derived cardiomyocytes bearing a pathogenic PKP2 mutation (PKP2 c.2013delC/WT), a corresponding knock-in mouse model carrying the equivalent murine mutation (Pkp2 c.1755delA/WT), and human explanted ACM hearts, to identify disease driving mechanisms. Pkp2 c.1755delA/WT mice over time displayed signs of ACM as observed by cardiac dysfunction and pathological remodeling. At a molecular level these mice showed a reduction in desmosomal and adherens junction proteins as well as disarray of the intercalated discs in areas of active fibrotic remodeling. These findings were validated in the mutant hiPSC-derived cardiomyocytes as well as human explanted ACM hearts, indicating both the conservation and relevance of protein degradation in the pathogenesis of the disease. Led by proteomics data, we demonstrated that the ubiquitin-proteasome system was responsible for the observed desmosomal protein degradation. These findings show the importance of appropriate disease modeling and provide means for therapeutic intervention for the prevention of ACM disease progression.
Project description:Plakophilin 2 (PKP2), encodes a plakophilin protein that belongs to the member of desmosomal proteins.PkP2 regulates some cell biological functions, but its downstream genes are not clear, so we constructed a stable cell line using H460 cells and identified its downstream target genes by RNA-seq technology
Project description:Plakophilin2 (PKP2) is a key component of desmosomes mostly recognized for its involvement in the fibro fatty infiltration of heart muscle under defective PKP2. While thoroughly explored in cardiomyocytes, less attention has been given to its role in fat cells. Here we report steadily increased PKP2 during adipogenesis, with expression levels reaching its apex in terminally differentiated adipocytes. Notably, the loss of this protein in adipocytes under a pro-inflammatory microenvironment demonstrates its commitment in maintaining the expression of genes required to nurture cell cycle. Then, we show that diminished expressions of this member of the armadillo repeat family in subcutaneous adipose tissue co-segregate with obesity, being normalized upon mild to intense weight loss. We also demonstrate that impaired PKP2 in human adipocytes breaks cell cycle dynamics to breed premature senescence, a key rheostat for stress induced adipose tissue dysfunction. Conversely, restoring PKP2 in inflamed adipocytes rewires E2F signalling towards re-activation of cell cycle and decreased senescence. Our findings bound the expression of PKP2 in fat cells to the physiopathology of obesity, and uncover a previously unknown defect in cell cycle and activated adipocyte senescence due to impaired PKP2.