Project description:Ischemic cardiomyopathy (ICM) leads to congestive heart failure and can cause sudden cardiac death due to arrhythmia. Existing molecular knowledge base of ICM is rudimentary because of lack of specific attribution to cell type and function. This study was designed to investigate cell-specific molecular remodeling of ion channels, exchangers and pumps, which are signaling molecules (SM) involved in electrical, signaling and mechanical functions of the heart. Atrial and ventricular myocytes were isolated by laser-capture microdissection from left atrium and ventricle of healthy and ICM human hearts. SM and their splice variants altered by ICM in cardiomyocytes were identified by splice microarray and validated by RT-PCR. Molecular profiling of ICM-related changes showed that SM in atrial and ventricular myocytes remodel following their unique programs. ICM affected 63 genes in ventricular myocytes and 12 genes in atrial myocytes. Only few of the identified genes were previously linked to human cardiac disfunctions. In our experiments we used 3 healthy hearts rejected from transplantation procedure and explanted ICM hearts from three male patients. Tissue samples were dissected from left ventricle and left atrial appendages. Atrial and ventricular myocytes were laser-capture microdissected from serial 7-8-µm thick cryostat sections. Individual cellular total RNA samples were analyzed on custom-built Human Ion Channel Splice Arrays slides (ExonHit) manufactured on the Ion Channel Splice Array sv1.1 platform representing 287 human SM, including 248 alternatively spliced ones in total 1655 splicing events and supplemented with capabilities to recognize connexins and ryanodine receptors.
Project description:Ischemic cardiomyopathy (ICM) leads to congestive heart failure and can cause sudden cardiac death due to arrhythmia. Existing molecular knowledge base of ICM is rudimentary because of lack of specific attribution to cell type and function. This study was designed to investigate cell-specific molecular remodeling of ion channels, exchangers and pumps, which are signaling molecules (SM) involved in electrical, signaling and mechanical functions of the heart. Atrial and ventricular myocytes were isolated by laser-capture microdissection from left atrium and ventricle of healthy and ICM human hearts. SM and their splice variants altered by ICM in cardiomyocytes were identified by splice microarray and validated by RT-PCR. Molecular profiling of ICM-related changes showed that SM in atrial and ventricular myocytes remodel following their unique programs. ICM affected 63 genes in ventricular myocytes and 12 genes in atrial myocytes. Only few of the identified genes were previously linked to human cardiac disfunctions.
Project description:Molecular remodeling of ion channels, exchangers and pumps in atrial and ventricular myocytes in ischemic cardiomyopathy: left ventricle DCM
Project description:Lamin A/C proteins, encoded by the LMNA gene, are intermediate filament proteins of the nuclear lamina, and predominantly expressed in differentiated cells including cardiomyocytes. Mutations in LMNA are associated with laminopathies, congenital diseases affecting muscle and homeostasis. One of the laminopathies associated with a missense mutation (N195K) in the A-type lamins results in dilated cardiomyopathy (DCM) with arrhythmias and sudden death. However it is unknown how the mutation in this LMNA gene contributes to the mechanism of arrhythmia and sudden death. To investigate this a mouse line expressing the Lmna-N195K (LmnaN195K/N195K) was used. Mutant mice demonstrated reduced fractional shortening, LV mass, wall thickness and dilated cardiomyopathy by echocardiography at 6 weeks consistent with human DCM, and died at an early age (6-7 weeks). Comparative cDNA microarray analysis from LmnaN195K/N195K and the wild type (WT) control ventricles at 6 weeks age revealed significant alterations in the expression of ion channels, transporter proteins, caveolins and associated proteins such as MAP kinases. Transmission electron microscopy analysis showed structural alterations of the ventricular myocytes with increase in number of caveolae. Quantitative Western blot analysis confirmed reduced expression for Cavβ (2 fold) subunits of the L-type Ca2+ channel. In contrast the expression levels of Cav3 (2.5 fold) was significantly increased. To investigate the functional impact of Lmna N195K on the ICa,L, we transiently expressed either the WT LMNA+GFP, Lmna N195K+GFP or GFP (control) in isolated neonatal mouse ventricular myocytes and performed whole cell patch clamp analysis. Transient expression of Lmna N195K significantly reduced (58 %) peak ICa,L (-6.0 ± 2 pA/pF, n=9) compared to GFP control (-14 ± 2 pA/pF, n=8). Expression of WT LMNA did not affect the ICa,L (-14.2 ± 2.5 pA/pF, n=8) compared to control. Conclusion: We conclude that Lmna N195K mutation results in reduced expression of ion channels and scaffolding proteins in the left ventricle with a significant reduction in peak ICa,L in ventricular myocytes and these may contribute to the mechanism of arrhythmia and dilated cardiomyopathy. 6 samples
Project description:We wanted to see whether the set of affected genes in ischemic cardiomyopathy (ICM) is the same or different as compared to dilated cardiomyopathy (DCM). To find this out, we placed the single DCM sample on the same microarray slide with the ICM samples. Analysis of microarray data with ICM samples only showed 63 affected genes, while that carried out with 2 ICM samples PLUS one DCM sample reduced this number to just four genes. From this result we conclude that ICM and DCM affect different sets of genes in ventricular myocytes. Keywords: Expression profiling by array From the associated publication: To find out whether the splice microarray results reported in Table 3 are disease-type specific, we supplemented the same splice microarray of ICM ventricular myocytes with one additional sample prepared from left ventricle of a 41-years old dilated cardiomyopathy male donor. The top-list ANOVA gene score annotation for combined altered CE&P genes in ventricular myocytes (Table 3) was reduced from 63 to just 4 genes (FXYD1 (Gfold = +2.4), HCN2 (-1.5), GLRA1 (-1.8) and GJC1 (-2.3)).
Project description:Loss of KChIP2 during cardiac stress has been suggested to have a transcriptional impact on cardiac ion channels contributing to maladaptive electrical remodeling. Therefore, we tested the consequence of KChIP2 loss, in the absence of cardiac stress, by treating cultured neonatal rat ventricular myocytes with shRNA for KChIP2 and subsequently performed whole-transcriptome microarray analysis to identify gene changes.
Project description:Loss of KChIP2 during cardiac stress has been suggested to have a transcriptional impact on cardiac ion channels through altered miRNA activity, contributing to maladaptive electrical remodeling. Therefore, we tested the consequence of KChIP2 loss, in the absence of cardiac stress, by treating cultured neonatal rat ventricular myocytes with siRNA for KChIP2 and subsequently performed miRNA microarray analysis to identify up-regulation of potential miRNA targets.
Project description:Lamin A/C proteins, encoded by the LMNA gene, are intermediate filament proteins of the nuclear lamina, and predominantly expressed in differentiated cells including cardiomyocytes. Mutations in LMNA are associated with laminopathies, congenital diseases affecting muscle and homeostasis. One of the laminopathies associated with a missense mutation (N195K) in the A-type lamins results in dilated cardiomyopathy (DCM) with arrhythmias and sudden death. However it is unknown how the mutation in this LMNA gene contributes to the mechanism of arrhythmia and sudden death. To investigate this a mouse line expressing the Lmna-N195K (LmnaN195K/N195K) was used. Mutant mice demonstrated reduced fractional shortening, LV mass, wall thickness and dilated cardiomyopathy by echocardiography at 6 weeks consistent with human DCM, and died at an early age (6-7 weeks). Comparative cDNA microarray analysis from LmnaN195K/N195K and the wild type (WT) control ventricles at 6 weeks age revealed significant alterations in the expression of ion channels, transporter proteins, caveolins and associated proteins such as MAP kinases. Transmission electron microscopy analysis showed structural alterations of the ventricular myocytes with increase in number of caveolae. Quantitative Western blot analysis confirmed reduced expression for Cavβ (2 fold) subunits of the L-type Ca2+ channel. In contrast the expression levels of Cav3 (2.5 fold) was significantly increased. To investigate the functional impact of Lmna N195K on the ICa,L, we transiently expressed either the WT LMNA+GFP, Lmna N195K+GFP or GFP (control) in isolated neonatal mouse ventricular myocytes and performed whole cell patch clamp analysis. Transient expression of Lmna N195K significantly reduced (58 %) peak ICa,L (-6.0 ± 2 pA/pF, n=9) compared to GFP control (-14 ± 2 pA/pF, n=8). Expression of WT LMNA did not affect the ICa,L (-14.2 ± 2.5 pA/pF, n=8) compared to control. Conclusion: We conclude that Lmna N195K mutation results in reduced expression of ion channels and scaffolding proteins in the left ventricle with a significant reduction in peak ICa,L in ventricular myocytes and these may contribute to the mechanism of arrhythmia and dilated cardiomyopathy.
Project description:Background: Atrial fibrillation (AF) causes atrial remodeling, and the left atrium (LA) is the favored substrate for maintaining AF. However, it remains unclear if AF remodels both atria differently and contributes to LA arrhythmogenesis and thrombogenesis. Results: AF was associated with differential LA-to-RA gene expression related to specific ion channels and pathways as well as upregulation of thrombogenesis-related genes in the LA appendage. Targeting the molecular mechanisms underlying the LA-to-RA difference and AF-related remodeling in the LA appendage may help provide new therapeutic options in treating AF and preventing thromboembolism in AF. Paired left atrial and right atrial specimens were obtained from 13 patients with persistent AF receiving valvular surgery. The Paired specimens were sent for microarray comparison. Selected results were validated by quantitative real time-PCR (q-PCR) and Western blotting. Ultrastructural changes in the atria were evaluated by immunohistochemistry.
Project description:Note this data set has identical data files: Files GSM40994.txt and GSM40995.txt. 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).