Intrinsic Endocardial Defects Contribute to Hypoplastic Left Heart Syndrome.
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ABSTRACT:
SUBMITTER: Miao Y
PROVIDER: S-EPMC7541479 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Hypoplastic left heart syndrome (HLHS) is characterized by underdevelopment of left sided structures including the ventricle, valves, and aorta1. Although the mechanisms of disease pathogenesis remain elusive due to a paucity of candidate genes and animal models, prevailing paradigm suggests that HLHS is a multigenic disease of co-occurring phenotypes2,3. Here, we report that zebrafish lacking two orthologs of the RNA binding protein RBFOX2, a gene previously linked to HLHS in humans4,5, display cardiovascular defects overlapping those in HLHS patients. In contrast to current models, we demonstrate that co-existing ventricular, valve, and aortic deficiencies in rbfox mutant zebrafish arise secondary to impaired myocardial function as all three phenotypes are rescued when Rbfox is expressed specifically in the myocardium. On a molecular and cellular level, we find diminished expression and alternative splicing of sarcomere and mitochondrial components in rbfox-deficient hearts that compromise sarcomere assembly and mitochondrial respiration, respectively. Injection of human RBFOX2 mRNA restores ventricular structure and function in rbfox mutant zebrafish, while HLHS-linked RBFOX2 variants fail to rescue. Taken together, our data suggest that mutations in RBFOX2 are causal for HLHS pathogenesis and provide a complimentary paradigm for HLHS emergence where co-existing ventricular, valve, and aortic deficiencies have a monogenic etiology caused by myocardial dysfunction.
2022-07-12 | MTBLS4176 | MetaboLights
Project description:BackgroundHypoplastic left heart syndrome (HLHS) is one of the most complex congenital cardiac malformations, and the molecular mechanism of heart failure (HF) in HLHS is still elusive.MethodsIntegrative bioinformatics analysis was performed to unravel the underlying genes and mechanisms involved in HF in HLHS. Microarray dataset GSE23959 was screened out for the differentially expressed genes (DEGs), after which the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses were carried out using the Metascape. The protein-protein interaction (PPI) network was generated, and the modules and hub genes were identified with the Cytoscape-plugin. And the integrated network of transcription factor (TF)-DEGs and miRNA-DEGs was constructed, respectively.ResultsA total of 210 DEGs were identified, including 135 up-regulated and 75 down-regulated genes. The functional enrichment analysis of DEGs pointed towards the mitochondrial-related biological processes, cellular components, molecular functions and signaling pathways. A PPI network was constructed including 155 nodes as well as 363 edges. And 15 hub genes, such as NDUFB6, UQCRQ, SDHD, ATP5H, were identified based on three topological analysis methods and mitochondrial components and functions were the most relevant. Furthermore, by integrating network interaction construction, 23 TFs (NFKB1, RELA, HIF1A, VHL, GATA1, PPAR-γ, etc.) as well as several miRNAs (hsa-miR-155-5p, hsa-miR-191-5p, hsa-mir-124-3p, hsa-miR-1-3p, etc.) were detected and indicated the possible involvement of NF-κB signaling pathways in mitochondrial dysfunction in HLHS.ConclusionThe present study applied the integrative bioinformatics analysis and revealed the mitochondrial-related key genes, regulatory pathways, TFs and miRNAs underlying the HF in HLHS, which improved the understanding of disease mechanisms and the development of novel therapeutic targets.
| S-EPMC8684406 | biostudies-literature
Project description:BackgroundComplex molecular programs in specific cell lineages govern human heart development. Hypoplastic left heart syndrome (HLHS) is the most common and severe manifestation within the spectrum of left ventricular outflow tract obstruction defects occurring in association with ventricular hypoplasia. The pathogenesis of HLHS is unknown, but hemodynamic disturbances are assumed to play a prominent role.MethodsTo identify perturbations in gene programs controlling ventricular muscle lineage development in HLHS, we performed whole-exome sequencing of 87 HLHS parent-offspring trios, nuclear transcriptomics of cardiomyocytes from ventricles of 4 patients with HLHS and 15 controls at different stages of heart development, single cell RNA sequencing, and 3D modeling in induced pluripotent stem cells from 3 patients with HLHS and 3 controls.ResultsGene set enrichment and protein network analyses of damaging de novo mutations and dysregulated genes from ventricles of patients with HLHS suggested alterations in specific gene programs and cellular processes critical during fetal ventricular cardiogenesis, including cell cycle and cardiomyocyte maturation. Single-cell and 3D modeling with induced pluripotent stem cells demonstrated intrinsic defects in the cell cycle/unfolded protein response/autophagy hub resulting in disrupted differentiation of early cardiac progenitor lineages leading to defective cardiomyocyte subtype differentiation/maturation in HLHS. Premature cell cycle exit of ventricular cardiomyocytes from patients with HLHS prevented normal tissue responses to developmental signals for growth, leading to multinucleation/polyploidy, accumulation of DNA damage, and exacerbated apoptosis, all potential drivers of left ventricular hypoplasia in absence of hemodynamic cues.ConclusionsOur results highlight that despite genetic heterogeneity in HLHS, many mutations converge on sequential cellular processes primarily driving cardiac myogenesis, suggesting novel therapeutic approaches.
| S-EPMC8542085 | biostudies-literature
Project description:Complex molecular programs in specific cell lineages govern human heart development. Hypoplastic left heart syndrome (HLHS) is the most severe congenital heart defect encompassing a spectrum of left-ventricular hypoplasia occurring in association with outflow-tract obstruction. The current clinical paradigm assumes HLHS is largely of hemodynamic origin. Here, by combining whole-exome sequencing of 87 HLHS parent-offspring trios and transcriptome of cardiomycytes (CMs) from healthy and patient native ventricles at different stages of development we identified perturbations in coherent gene programs controlling ventricular muscle lineage development. Single-cell and 3D molecular/functional modeling with iPSCs demonstrated intrinsic defects in the cell-cycle/ciliogenesis/autophagy hub resulting in disrupted differentiation of early cardiac progenitor (CP) lineages and ultimate defective CM-subtype differentiation/maturation in HLHS. Moreover, premature cellcycle exit of ventricular CM prevents tissue response to cues of developmental growth leading to multinucleation/polyploidy, accumulation of DNA damage, exacerbated apoptosis, and eventually ventricle hypoplasia. Our results highlight how genetic heterogeneity in HLHS converges in perturbations of sequential cellular processes driving cardiogenesis and facilitate potential novel nodes for therapy beside surgical intervention.
2022-02-15 | PXD014812 | Pride
Project description: Not available
| S-EPMC7583658 | biostudies-literature
Project description:Hypoplastic left heart syndrome (HLHS) is a heterogeneous, lethal combination of congenital malformations that result in a heart unable to sustain systemic circulation. The genetic determinants of this disorder are largely unknown. Evidence of copy number variants (CNVs) contributing to the genetic etiology of HLHS and other congenital heart defects (CHDs) has been mounting. However, the functional effects of such CNVs have not been examined, particularly in cases where the variant of interest is found in only a single patient. Initially whole-genome SNP microarrays were employed to detect CNVs in two patient cohorts (N = 70 total) predominantly diagnosed with some form of nonsyndromic HLHS. We discovered 16 rare variants adjacent to or overlapping 20 genes associated with cardiovascular or premature lethality phenotypes in mouse knockout models. Fifteen of the 16 variants were identified in separate patients, suggestive of a private mutation model of disease. We evaluated the impact of selected variants on the expression of nine of these genes through quantitative PCR on cDNA derived from patient heart tissue. Four genes displayed significantly altered expression in patients with an overlapping or proximal CNV verses patients without such CNVs. Thus, rare and private genomic imbalances perturb transcription of genes affecting cardiogenesis in a subset of nonsyndromic HLHS patients. Some of these genes influence extracellular matrix structure, cardiac neural crest development, and coronary vascularization. A total of 70 samples from CHD patients, mostly with nonsyndromic HLHS, yielded SNP genotypes and probe intensity ratios of sufficient quality for CNV identification. Two classes of CNV detection algorithms (HMM and CBS) were employed. After identification, concordant entries were subjected to selection criteria based on rarity and gene content, which produced putative candidate genes for follow-up experiments.
2015-12-10 | E-GEOD-66032 | biostudies-arrayexpress
Project description:Congenital heart disease (CHD) affects up to 1% of live births. Although a genetic etiology is indicated by an increased recurrence risk, sporadic occurrence suggests that CHD genetics is complex. Here, we show that hypoplastic left heart syndrome (HLHS), a severe CHD, is multigenic and genetically heterogeneous. Using mouse forward genetics, we report what is, to our knowledge, the first isolation of HLHS mutant mice and identification of genes causing HLHS. Mutations from seven HLHS mouse lines showed multigenic enrichment in ten human chromosome regions linked to HLHS. Mutations in Sap130 and Pcdha9, genes not previously associated with CHD, were validated by CRISPR-Cas9 genome editing in mice as being digenic causes of HLHS. We also identified one subject with HLHS with SAP130 and PCDHA13 mutations. Mouse and zebrafish modeling showed that Sap130 mediates left ventricular hypoplasia, whereas Pcdha9 increases penetrance of aortic valve abnormalities, both signature HLHS defects. These findings show that HLHS can arise genetically in a combinatorial fashion, thus providing a new paradigm for the complex genetics of CHD.
| S-EPMC5737968 | biostudies-literature
Project description:ObjectiveMicro-RNAs (miRNAs) are important regulators of gene expression through interaction with the 3'UTR of target messenger RNAs (mRNAs). The role of miRNAs has been extensively studied in adult human and nonhuman animal models of heart disease. Hypoplastic left heart syndrome (HLHS) is the most common form of severe congenital heart disease and is an important cause of morbidity and mortality in infants and children. The objective of this work was to analyze the miRNA profile in HLHS patients.Methods and resultsmiRNA profile was determined in the right ventricle with the use of miRNA array, and expression was validated with the use of reverse-transcription polymerase chain reaction (RT-PCR). Based on bioinformatics analysis, targets were selected and their expression analyzed with the use of RT-PCR.We found that the miRNA profile of HLHS is novel, with few similarities between pediatric and adult idiopathic dilated cardiomyopathy. Moreover, our analysis identified putative targets for these miRNAs that are known to be important for cardiac development and disease, and that miRNAs and their putative targets are antithetically regulated. We also found that miRNA expression changes with stage of surgery, suggesting that volume unloading of the ventricle has important consequences for gene expression.ConclusionsOur data suggest a unique miRNA profile for HLHS that may be associated with defects in cardiac development and disease.
| S-EPMC4276459 | biostudies-literature
Project description:Hypoplastic left heart syndrome (HLHS) is one of the most devastating forms of congenital heart defects. Previous studies have only focused on intrinsic defects in the myocardium. However, this does not sufficiently explain the abnormal development of the cardiac valve, septum, and vasculature, which are known to originate from the endocardium. Here, using single-cell RNA profiling, induced pluripotent stem cells, and fetal heart tissue with an underdeveloped left ventricle, we identified a developmentally impaired endocardial cell population in HLHS. The intrinsic endocardial deficits contributed to abnormal endothelial to mesenchymal transition, NOTCH signaling, and extracellular matrix organization, all of which are key factors in valve formation. Consequentially, endocardial abnormalities conferred reduced proliferation and maturation of cardiomyocytes through a disrupted fibronectin-integrin interaction. Several known HLHS de novo mutations all contributed to the abnormal endocardial gene expression through the alteration of promoter/enhancer activities. These mechanistic discoveries provide an alternative angle for early intervention and heart regeneration in HLHS.
2020-08-17 | GSE138979 | GEO
Project description:Hypoplastic left heart syndrome (HLHS) is a clinically and anatomically severe form of congenital heart disease (CHD). Although prior studies suggest that HLHS has a complex genetic inheritance, its etiology remains largely unknown. The goal of this study was to characterize a risk gene in HLHS and its effect on HLHS etiology and outcome. We performed next-generation sequencing on a multigenerational family with a high prevalence of CHD/HLHS, identifying a rare variant in the α-myosin heavy chain (MYH6) gene. A case-control study of 190 unrelated HLHS subjects was then performed and compared with the 1000 Genomes Project. Damaging MYH6 variants, including novel, missense, in-frame deletion, premature stop, de novo, and compound heterozygous variants, were significantly enriched in HLHS cases (P < 1 × 10-5). Clinical outcomes analysis showed reduced transplant-free survival in HLHS subjects with damaging MYH6 variants (P < 1 × 10-2). Transcriptome and protein expression analyses with cardiac tissue revealed differential expression of cardiac contractility genes, notably upregulation of the β-myosin heavy chain (MYH7) gene in subjects with MYH6 variants (P < 1 × 10-3). We subsequently used patient-specific induced pluripotent stem cells (iPSCs) to model HLHS in vitro. Early stages of in vitro cardiomyogenesis in iPSCs derived from two unrelated HLHS families mimicked the increased expression of MYH7 observed in vivo (P < 1 × 10-2), while revealing defective cardiomyogenic differentiation. Rare, damaging variants in MYH6 are enriched in HLHS, affect molecular expression of contractility genes, and are predictive of poor outcome. These findings indicate that the etiology of MYH6-associated HLHS can be informed using iPSCs and suggest utility in future clinical applications.
| S-EPMC5206387 | biostudies-literature