Project description:Central questions like cardiomyocyte subtype emergence during cardiogenesis or availability of cardiomyocyte subtypes for cell replacement therapy require selective identification and purification of atrial and ventricular cardiomyocytes. However, characterization and implementation of pure cardiomyocyte subtypes is still challenging due to technical limitations. Our aim was to identify surface markers enabling the selective detection and purification of atrial and ventricular cardiomyocytes from mouse hearts. In a surface marker screen we found differential expression of CD49f in atrial and ventricular embryonic cardiomyocytes (E13.5). By flow cytometry we could correlate a high CD49f expression with MLC-2a on the single cell level; a low CD49f expression corresponded to MLC-2v. Based on the persisting differential CD49f expression we developed purification protocols for cardiomyocytes subtypes from the developing mouse heart. Flow sorting of E15.5 hearts into ErbB-2+/CD49flow and ErbB-2+/CD49fhigh cells led to a selective depletion (CD49flow) or enrichment of MLC-2a+ cells (CD49fhigh). We found a corresponding CD49f-dependent distribution of MLC-2a when pre-enriched neonatal cardiomyocytes (P2) were flow-sorted into CD49flow and CD49fhigh. Atrial and ventricular identity was confirmed by expression profiling and patch clamp analysis of sorted embryonic hearts, which unequivocally demonstrated that the sorted cells were viable and functional. For the first time, we introduce a non-genetic, antibody-based approach to specifically isolate atrial and ventricular cardiomyocytes from mouse hearts of various developmental stages. This newly gained capability of obtaining highly pure, viable cells will facilitate in-depths characterization of the individual cellular subsets and will aid translational research and therapeutic applications. The dataset comprises four different cardiomyocytes subtypes from the developing mouse heart. Embryonic (E15.5) hearts were dissociated and flow-sorted into ErbB-2+/CD49flow and ErbB-2+/CD49fhigh cardiomyocytes. Neonatal (P2) hearts were dissociated, contaminating non-myocytes were removed by MACS depletion, and the purified cardiomyocytes were flow-sorted into CD49flow and CD49fhigh cardiomyocytes. Four biological replicates were available for each sample groups. Microarray analysis was conducted on the Agilent Whole Mouse Genome Oligo Microarray 8x60K platform.

Project description:GSE2240 contains two different experimental subsets: 1) Comparison of atrial and ventricular gene expression (atrial tissue of patients with sinus rhythm vs. human left ventricular non-failing myocardium) The purpose of our investigation was to identify the transcriptional basis for ultrastructural and functional specialization of human atria and ventricles. Using exploratory microarray analysis (Affymetrix U133A+B), we detected 11,740 transcripts expressed in human heart, representing the most comprehensive report of the human myocardial transcriptome to date. Variation in gene expression between atria and ventricles accounted for the largest differences in this data set, as 3.300 and 2.974 transcripts showed higher expression in atria and ventricles, respectively. Functional classification based on Gene Ontology identified chamber-specific patterns of gene expression and provided molecular insights into the regional specialization of cardiomyocytes, correlating important functional pathways to transcriptional activity: Ventricular myocytes preferentially express genes satisfying contractile and energetic requirements, while atrial myocytes exhibit specific transcriptional activities related to neurohumoral function. In addition, several pro-fibrotic and apoptotic pathways were concentrated in atrial myocardium, substantiating the higher susceptibility of atria to programmed cell death and extracellular matrix remodelling observed in human and experimental animal models of heart failure. Differences in transcriptional profiles of atrial and ventricular myocardium thus provide molecular insights into myocardial cell diversity and distinct region-specific adaptations to physiological and pathophysiological conditions (Barth AS et al., Eur J Physiol, 2005). 2) Comparison of atrial gene expression in patients with permanent atrial fibrillation and sinus rhythm. Atrial fibrillation is associated with increased expression of ventricular myosin isoforms in atrial myocardium, regarded as part of a dedifferentiation process. Whether re-expression of ventricular isoforms in atrial fibrillation is restricted to transcripts encoding for contractile proteins is unknown. Therefore, this study compares atrial mRNA expression in patients with permanent atrial fibrillation to atrial mRNA expression of patients with sinus rhythm as well as to ventricular gene expression using Affymetrix U133 arrays. In atrial myocardium, we identified 1.434 genes deregulated in atrial fibrillation, the majority of which, including key elements of calcium-dependent signaling pathways, displayed down-regulation. Functional classification based on Gene Ontology provided the specific gene sets of the interdependent processes of structural, contractile and electrophysiological remodeling. In addition, we demonstrate for the first time a prominent up-regulation of transcripts involved in metabolic activities, suggesting an adaptive response to an increased metabolic demand in fibrillating atrial myocardium. Ventricular-predominant genes were five times more likely to be up-regulated in atrial fibrillation (174 genes up-regulated, 35 genes down-regulated), while atrial-specific transcripts were predominantly down-regulated (56 genes up-regulated, 564 genes down-regulated). Overall, in atrial myocardium, functional classes of genes characteristic of ventricular myocardium were found to be up-regulated (e.g. metabolic processes) while functional classes predominantly expressed in atrial myocardium were down-regulated in atrial fibrillation (e.g. signal transduction and cell communication). Therefore, dedifferentiation with adoption of a ventricular-like signature is a general feature of the fibrillating atrium, uncovering the transcriptional response pattern in pmAF (Barth AS et al., Circ Res, 2005). Keywords = human myocardium Keywords = atrial fibrillation Keywords = sinus rhythm Keywords = left ventricular gene expression Keywords: other

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BioChIP-seq analysis of atrial and ventricular cardiomyocytes

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