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.
Project description:This research aimed to identify protein biomarkers of right ventricular dysfunction in patients with advanced heart failure with reduced ejection fraction (HFrEF). Samples of myocardium from both, right and left ventricles (RV, LV) were obtained from 10 HFrEF patients with right ventricular dysfunction (RVD), 10 HFrEF patients without RVD (noRVD) undergoing heart transplantation, and 10 non-failing unused donor hearts (Control). Tissue samples were homogenized and extracted using mild Triton X-100 detergent and processed by SP3 extraction to remove the detergent prior the analysis, (LFQ) proteomic analysis identified a total of 4 032 proteins in the left ventricle and 3 788 proteins in the right ventricle.
Project description:The left and right ventricles of the human heart are functionally and developmentally distinct such that genetic or acquired insults can cause dysfunction in one or both ventricles resulting in heart failure. First, we performed unbiased quantitative mass spectrometry on the myocardium of 25-27 pre-mortem cryopreserved non-diseased human hearts to compare the metabolome and proteome between the normal left and right ventricles. Constituents of gluconeogenesis, glycolysis, lipogenesis, lipolysis, fatty acid catabolism, the citrate cycle and oxidative phosphorylation were down-regulated in the left ventricle, while glycogenesis, pyruvate and ketone metabolism were up-regulated. Inter-ventricular significance of these metabolic pathways was then found to be diminished within end-stage dilated cardiomyopathy and ischaemic cardiomyopathy (n = 30-33), while heart failure-associated pathways were increased in the left ventricle relative to the right within ischaemic cardiomyopathy, such as fluid sheer-stress, increased glutamine to glutamate ratio, and down-regulation of contractile proteins indicating a left ventricular pathological bias.
Project description:We created mice, which are deficient for Myc specifically in cardiac myocytes by crossing crossed Myc-floxed mice (Mycfl/fl) and MLC-2VCre/+ mice. Serial analysis of earlier stages of gestation revealed that Myc-deficient mice died prematurely at E13.5-14.5. Morphological analyses of E13.5 Myc-null embryos showed normal ventricular size and structure; however, decreased cardiac myocyte proliferation and increased apoptosis was observed. BrdU incorporation rates were also decreased significantly in Myc-null myocardium. Myc-null mice displayed a 3.67-fold increase in apoptotic cardiomyocytes by TUNEL assay. We examined global gene expression using oligonucleotide microarrays. Numerous genes involved in mitochondrial death pathways were dysregulated including Bnip3L and Birc2. Keywords: wildtype vs Myc-null
Project description:Several inherited arrhythmias primarily affect the right ventricle, including Brugada syndrome and arrhythmogenic cardiomyopathy, however the molecular basis of this chamber predilection is not well understood. Right and left ventricular cardiomyocytes derive from distinct progenitor populations. Here, we show that Hrt2, a gene associated with Brugada syndrome, is a direct target of Wnt signaling in the right ventricle and Notch signaling in the left ventricle. Perturbations of Wnt and Notch signaling during development and in the adult lead to chamber-specific transcriptional effects on Hrt2 expression associated with distinct binding patterns to Hrt2 enhancers. Differential enhancer binding is present at early developmental stages when the signaling pathways are active and persists into adulthood. Consistent with chamber-specific regulation, mice deficient in Wnt transcriptional activity dysregulate only a small fraction of transcripts in common between ventricles. Wnt target gen es important for cellular electrophysiology are differentially regulated, resulting in perturbed cardiac conduction and cellular electrophysiological parameters only within the right ventricle. Ex vivo and in vivo physiologic stimulation of the right ventricle is sufficient to induce ventricular tachycardia in Wnt transcriptionally inactive hearts, while left ventricular stimulation has no effect. Taken together, these data delineate mechanisms underlying ventricular-specific arrhythmia susceptibility due to embryonic programming.
Project description:Several inherited arrhythmias primarily affect the right ventricle, including Brugada syndrome and arrhythmogenic cardiomyopathy, however the molecular basis of this chamber predilection is not well understood. Right and left ventricular cardiomyocytes derive from distinct progenitor populations. Here, we show that Hrt2, a gene associated with Brugada syndrome, is a direct target of Wnt signaling in the right ventricle and Notch signaling in the left ventricle. Perturbations of Wnt and Notch signaling during development and in the adult lead to chamber-specific transcriptional effects on Hrt2 expression associated with distinct binding patterns to Hrt2 enhancers. Differential enhancer binding is present at early developmental stages when the signaling pathways are active and persists into adulthood. Consistent with chamber-specific regulation, mice deficient in Wnt transcriptional activity dysregulate only a small fraction of transcripts in common between ventricles. Wnt target gen es important for cellular electrophysiology are differentially regulated, resulting in perturbed cardiac conduction and cellular electrophysiological parameters only within the right ventricle. Ex vivo and in vivo physiologic stimulation of the right ventricle is sufficient to induce ventricular tachycardia in Wnt transcriptionally inactive hearts, while left ventricular stimulation has no effect. Taken together, these data delineate mechanisms underlying ventricular-specific arrhythmia susceptibility due to embryonic programming.
Project description:We created mice, which are deficient for Myc specifically in cardiac myocytes by crossing crossed Myc-floxed mice (Mycfl/fl) and MLC-2VCre/+ mice. Serial analysis of earlier stages of gestation revealed that Myc-deficient mice died prematurely at E13.5-14.5. Morphological analyses of E13.5 Myc-null embryos showed normal ventricular size and structure; however, decreased cardiac myocyte proliferation and increased apoptosis was observed. BrdU incorporation rates were also decreased significantly in Myc-null myocardium. Myc-null mice displayed a 3.67-fold increase in apoptotic cardiomyocytes by TUNEL assay. We examined global gene expression using oligonucleotide microarrays. Numerous genes involved in mitochondrial death pathways were dysregulated including Bnip3L and Birc2. Hearts were taken from wide type and Myc-null Mouse embryos at E13.5 under the dissecting scope. Cardiac myocyte RNA was isolated using TRIZOL®Reagent Total RNA (100 ng) was hybridized to the Sentrix® MouseRef-8 Expression BeadChip that contains probes for ~24,000 transcripts. GeneChips were scanned using the Hewlett-Packard GeneArray Scanner G2500A. The data were analyzed with Illumina Inc. BeadStudio version 1.5.0.34 and normalized by rank invariant method.