Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of infarcted and non-infarcted left ventricles at different time points to study the molecular mechanism of myocardial infarction.

ABSTRACT: This dataset is a time series (1 hour [h], 4 hours, 24 hours, 48 hours, 1 week [w], and 8 weeks) intended to compare normal functioning left ventricles [lv + lv2] with infarcted [ilv] and non-infarcted left ventricles [nilv]. ilv samples are taken from the region between the LAD artery and the apex on a mouse with myocardial infarction. Lv2 samples are from the same region in a sham operated mouse. Nilv samples are taken from the region above the infartion and the left ventricle [lv] samples mimic that region in a sham mouse. The lv and lv2 samples can be compared as both are from normal functioning hearts. For more information visit http://cardiogenomics.med.harvard.edu/groups/proj1/pages/mi_home.html

ORGANISM(S): Mus musculus

DISEASE(S): myocardial infarction

SUBMITTER: Martina Schinke

PROVIDER: E-GEOD-775 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:To find which genes were significantly modulated by Valsartan in non-infarcted left ventricle, 4 weeks after coronary artery ligation, and to correlate emerging modulated pathways with histology and cardiac magnetic resonance (CMR) imaging. The goal was to validate the estimation of the systolic dysfunction and of the regions preserved by pharmacological treatment performed with a CMR index. Title of the associated submitted paper: Evaluation of left ventricle function by regional fractional area change (RFAC) in a mouse model of myocardial infarction secondary to Valsartan treatment. Abstract: Purpose: Left ventricle (LV) regional fractional area change (RFAC) measured by cardiac magnetic resonance (CMR) allows the non-invasive localization and quantification of the extent of myocardial infarction (MI), and could be applied to assess the effectiveness of pharmacological or regenerative therapies. Here we investigate the ability of RFAC to identify regional dysfunction and discriminate the effect of pharmacological treatment with valsartan, a selective antagonist of angiotensin II type 1 receptor, in a model of MI. Methods: C57BL/6N mice, undergoing coronary artery ligation, were divided into two groups: untreated (MI) or treated with Valsartan (MI+Val). Sham-operated mice were used as a control. Cardiac dimensions and function were assessed at baseline, 24 hours, 1 and 4 weeks post surgery by CMR and echocardiography. At sacrifice histology and whole-genome gene expression profiling were performed. Results: RFAC was able to detect significant differences between treatment groups whereas the global ejection fraction was not. RFAC showed greater loss of contractility in remote non-infarcted myocardium in MI group than in MI+Val group. Consistently, in the same region MI+Val mice showed reduced myocyte hypertrophy, fibroblast proliferation, and fibrosis and modulation of target genes; in addition, left atrium volumes, appendage length and duct contractility were preserved. Conclusion: In this study, RFAC effectively estimated the degree of systolic dysfunction and discriminated the regions preserved by pharmacological treatment. RFAC index is a promising tool to monitor changes in LV contractility and to assess the effectiveness of therapeutic regimens in clinical settings.

Project description:We report a genome-wide survey of early responses of the mouse heart transcriptome to acute myocardial infarction (AMI). For three regions of the left ventricle (LV), namely ischemic/infarcted tissue (IF), the surviving LV free wall (FW) and the interventricular septum (IVS), 36,899 transcripts were assayed at six time points from 15 min to 48 h post-AMI in both AMI and sham surgery mice. For each transcript, temporal expression patterns were systematically compared between AMI and sham groups, which identified 515 AMI-responsive genes in IF tissue, 35 in the FW, 7 in the IVS, with three genes induced in all three regions. Using the literature, we assigned functional annotations to all 519 nonredundant AMI-induced genes and present two testable models for central signaling pathways induced early post-AMI. First, the early induction of 15 genes involved in assembly and activation of the activator protein-1 (AP-1) family of transcription factors implicates AP-1 as a dominant regulator of earliest post-ischemic molecular events. Second, dramatic increases in transcripts for arginase 1 (ARG1), the enzymes of polyamine biosynthesis and protein inhibitor of nitric oxide synthase (NOS) activity indicates that NO production may be regulated, in part, by inhibition of NOS and coordinate depletion of the NOS substrate, L-arginine. ARG1 was the single most highly induced transcript in the database (121-fold in IF region) and its induction in heart has not been previously reported. Keywords: heart attack, mouse, time course, regional responses We report temporal and regional changes in steady state mRNA levels in the mouse LV following a surgically-induced AMI. Three regions of the infarcted LV were surveyed: IF, FW and IVS. For each region, mRNA levels were assayed at t=0 and six time points after occlusion of the left anterior descending coronary artery (t = 15 min, 1 h, 4 h, 12 h, 24 h, 48 h). As control, an identical time course was carried out in the mouse LV after sham surgery in which the suture was passed under the artery, but not ligated. For sham surgical mice and naïve mice (t=0), the IVS and the LV free wall were harvested and assayed. The AMI and sham time courses were repeated for a total of two independent repetitions of the experiment. For each repetition, 96 GeneChips were hybridized. Thus, for two repetitions, 192 GeneChips (2 x 96) were hybridized. In addition, the naïve time point was assayed a second time during Repetition 1 for six additional GeneChips (two tissues x three chips). The overall total number of samples is 198 GeneChips (192 + 6). Total RNA was isolated from each individual tissue sample. Equal weights of total RNA from 4-10 mice were combined for each LV region, time point and treatment. Copy RNA mixtures were synthesized from each total RNA pool and hybridized to the Affymetrix GeneChip set MG U74 v2 (A, B, and C) that carries 36,899 probe sets. The global normalization of fluorescence emissions for the 198 GeneChips used in this study and their conversion to relative transcript concentrations measured in relative fluorescence units (RFU) was conducted using Robust Multi-array Averaging (RMA; www.bioconductor.org). Each of the 198 Accessions is titled as follows: time point / treatment / tissue, repetition, GeneChip. The additional assays of naïve mice in Repetition 1 are labeled “Naive2”.

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Transcription profiling of infarcted and non-infarcted left ventricles at different time points to study the molecular mechanism of myocardial infarction.

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