Identification of PITX2 as a novel factor in arrhythmogenic cardiomyopathy pathogenesis [KI]
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE208212 | GEO | 2023/03/02
REPOSITORIES: GEO
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Project description:In this study, we identified a novel heterozygous variant within DSP (c.3562T>C) in a patient diagnosed with ACM. Using CRISPR/Cas9 we corrected patient-derived human induced pluripotent stem cells (hiPSC) and created a knock-in (KI) hiPSC line with the same mutation. Compared to wildtype cardiomyocytes, we observed a prolonged action potential duration (APD) and reduced expression of desmosomal components, which was paralleled by abnormal levels of essential cardiac ion channels. Strikingly, the transcription factor paired-like homeodomain 2 (PITX2), which acts as a repressor of ion channel-related genes, was induced in these cells. Together, we identified PITX2 as a potential missing link between mutations in DSP and the cardiac conductance abnormalities often seen in these patients.
2023-03-02 | GSE208213 | GEO
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.
2023-03-23 | GSE160289 | GEO
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.
2023-03-23 | GSE199925 | GEO
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.
2023-11-18 | PXD020605 | Pride
Project description:Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) are commonly used to model arrhythmogenic cardiomyopathy (ACM), a heritable cardiac disease characterized by severe ventricular arrhythmias, fibrofatty myocardial replacement and progressive ventricular dysfunction. Although ACM is inherited as an autosomal dominant disease, incomplete penetrance and variable expressivity are extremely common, resulting in different clinical manifestations. Here, we propose hiPSC-CMs as a powerful in vitro model to study incomplete penetrance in ACM. Six hiPSC lines were generated from blood samples of three ACM patients carrying a heterozygous deletion of exon 4 in the PKP2 gene, two asymptomatic (ASY) carriers of the same mutation and one healthy control (CTR), all belonging to the same family. Whole exome sequencing was performed in all family members and hiPSC-CMs were examined by ddPCR, western blot, Wes™ immunoassay system, patch clamp, immunofluorescence and RNASeq. Our results show molecular and functional differences between ACM and ASY hiPSC_x0002_CMs, including a higher amount of mutated PKP2 mRNA, a lower expression of the connexin-43 protein, a lower overall density of sodium current, a higher intracellular lipid accumulation and sarcomere disorganization in ACM compared to ASY hiPSC_x0002_CMs. Differentially expressed genes were also found, supporting a predisposition for a fatty phenotype in ACM hiPSC-CMs. These data indicate that hiPSC-CMs are a suitable model to study incomplete penetrance in ACM.
2023-07-14 | GSE222793 | GEO
Project description:Introduction: Atrial fibrillation (AF) is the most common arrhythmia and affects around 1% of the population with increasing incidence and substantial morbidity. Functional effects of genetic variants associated with AF should help to identify targets involved in AF initiation and/or subsequent remodeling. Gene variants next to the gene of the transcription factor PITX2 (paired-like homeodomain transcription factor 2) showed the strongest association with AF. A significant number of AF patients showed reduced PITX2 levels in the left atrium. Mouse models have been used to study functional aspects of PITX2 gene deletion (“knock out”), but there are substantial differences in atrial electrophysiology between mouse and human . HiPSC-CM should be able to bridge the gap, provided the cells reproduce typical characteristics of human atrium. Methods: PITX2 knock out samples from a control cell line of human induced pluripotent stem cells (hiPSC) were obtained. Differentiation and generation of Atrial-like engineered heart tissue (aEHT) was performed. RNA-sequencing (RNA-Seq), Quantitative Real-time PCR (RT-qPCR), Protein analysis by Western Blot, Contraction and force analysis, action potential measurements, Calcium current measurements and differential gene expression analysis were run on the samples. Results: Effective knock out of PITX2 was confirmed by mRNA sequencing and WB. It was shown that PITX2 deficiency reduces contraction force. PITX2 deficiency induces action potential triangulation with more negative maximum diastolic potential. Activation of muscarinic receptors shortens APD in both PITX2 knockout and controls but hyperpolarization is lost in PITX2 knock out. It was shown that Ca2+ current density is smaller in PITX2 knock out than controls. We found that more negative MDP in PITX2 knock out is not associated with higher IK1. Conclusion: We improved atrial differentiation, coming very close to human atrial electrophysiology. We demonstrate that PITX2 deficiency induces key characteristics known from persistent AF.
2024-05-31 | GSE175944 | GEO
Project description:The RNA-Seq studies performed in the endomyocardial biopsy samples from human patients with defined truncating mutations in the DSP gene and normal right ventricular size and function, identified dysregulation of over two-dozen TRs, including the Hippo/cWNT pathways, early in the course of ACM. The findings of the RNA-Seq were corroborated by immunoblotting and immunofluorescence studies showing reduced protein levels of the TRs of the Hippo/cWNT pathways in the ACM hearts. Dysregulation of these pathways early and prior to the onset of cardiac dysfunction suggest their pathogenic role in ACM.
2023-08-24 | GSE156869 | GEO
Project description:Desmosomes are specialized cell-cell junctions critically important in the heart, where their disruption promotes arrhythmogenic cardiomyopathy (ACM). Individuals carrying truncating variants in the desmosomal gene desmoplakin (DSP) often show a prominent inflammatory component in the absence of known antigenic stimuli, termed “hot phase” arrythmia. To assess the role of innate immune activation in DSP-cardiomyopathy, we generated engineered heart tissues (EHTs) from two patients with heterozygous DSP truncation variants (DSPtv, p.E1597X and p.R1951X). We also generated EHTs with homozygous DSP deletion (DSP-/-) for modeling. DSP-/- EHTs revealed impaired force production and reduced conduction velocity compared to isogenic controls, features consistent with ACM. RNA sequencing and protein characterization demonstrated a dramatic increase in innate immune activation in DSP-/- EHTs. Similarly, patient-derived DSPtv EHTs show enhanced sensitivity to inflammatory stimuli seen as reduced contractility and greater cytokine release. Inhibition of NFκB signaling improved baseline force production and mechanical response to strain in DSPtv EHTs, indicating that anti-inflammatory modulation may improve mechanical function in DSP deficient hearts. Furthermore, genomic correction of p.R1951X using adenine base editing reduced inflammatory biomarkers in cultured EHTs. Taken together, these data identify that DSPtv promote innate immune activation, creating an arrhythmogenic substrate in the concealed phase of ACM.
2024-07-03 | GSE248187 | GEO
Project description:The Pitx2 gene encodes a homeobox transcription factor that is required for mammalian development. Disruption of PITX2 expression in humans causes congenital heart diseases and is associated with atrial fibrillation (AF), however, the cellular and molecular processes dictated by Pitx2 during cardiac ontogeny remain unclear. To characterize the role of Pitx2 during murine heart development we sequenced over 75,000 single cardiac cell transcriptomes between two key developmental timepoints in control and Pitx2-null embryos. We uncovered that cardiac cell composition was dramatically altered in mutants at both E10.5 and E13.5. Interestingly, the differentiation dynamics of both anterior and posterior second heart field derived progenitor cells were disrupted in Pitx2 mutants. We also uncovered evidence for defects in left-right asymmetry within atrial cardiomyocyte populations. Furthermore, we were able to detail defects in cardiac outflow tract and valve development associated with Pitx2. Our findings offer insight into Pitx2 biology and provide a compilation of gene expression signatures for further detailing the complexities of heart development that will serve as the foundation for future studies of cardiac morphogenesis, congenital heart disease, and arrhythmogenesis.
2019-06-03 | GSE131181 | GEO
Project description:Pitx2 is the homeobox gene located in proximity to the human 4q25 familial atrial fibrillation locus. Pitx2 haploinsufficient mice are prone to pacing induced atrial fibrillation indicating that reduced Pitx2 promotes an arrhythmogenic substrate within the atrium. Here, we inactivated Pitx2 in postnatal heart and discovered that unstressed adult Pitx2 mutant mice had sinus node dysfunction with impaired atrial conduction, an arrhythmia closely associated with atrial fibrillation. A genome-wide search for Pitx2 transcriptional targets using ChIP-sequencing and RNA expression profiling shows that Pitx2 represses target genes encoding cell junction proteins, ion channels, and critical transcriptional regulators many of which have been implicated in human atrial fibrillation by genome wide association studies. Our findings unveil a Pitx2 postnatal arrhythmogenic function, novel Pitx2 target genes relevant to atrial fibrillation, and reveal that Pitx2 stabilizes the intercalated disc in postnatal atrium.
2014-02-01 | GSE47928 | GEO