AMPKα1 deletion in myofibroblasts exacerbates post myocardial infarction fibrosis by a miR-125b and Connexin 43 mechanism
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ABSTRACT: Myofibroblasts (MFs) are crucial components of the fibrotic remodeling after myocardial infarction (MI). We have previously demonstrated the centrality of AMPKα1 in post-MI remodeling. Here, we investigate the effects of MF-specific deletion of AMPKα1 on left ventricular (LV) adaptation following MI, and the underlying molecular mechanisms. Importantly, MF-restricted AMPKα1 conditional knockout (cKO) hearts exhibit exacerbated post-MI adverse LV remodeling and are characterized by exaggerated fibrotic response, compared to wild-type (WT) hearts. Myofibroblast proliferation significantly increases in cKO infarcted hearts, coincident with a significant reduction of Connexin 43 (Cx43) expression in MFs. Mechanistically, lack of AMPKα1 in MFs enhances miR-125b expression, which, in turn, downregulates Cx43. Collectively, our data demonstrate a cardinal role for MF-AMPKα1 in cardiac remodeling, as its lineage-specific inactivation accentuates fibrosis and LV dilatation following MI. The deleterious effects of MF-specific AMPKα1 deletion are mediated via Cx43, and its post-transcriptional regulation by miR-125b.
Project description:Wild type, female, C57BL/6 mice were subjected to sham (n=6) surgery, or TAC + MI to cause progressive LV remodeling (n=12). At 2wks post-TAC, one group of mice underwent de-banding (HF-DB, n=6), whereas in a second group of mice the band remained intact (HF; n = 6). LV remodeling was evaluated by 2D echocardiography at 14 days post-TAC+MI , and 4 wks post-debanding. At 6 wks the hearts were excised and analyzed for changes in gene expression using transcriptional profiling. e-banding in the HF-DB mice resulted in normalization of LV volumes and LV mass, and normalization of cardiac myocyte hypertrophy at 6wks, without significant changes in myofibrillar collagen in the HF and HF-DB mice. Both LV ejection fraction (LVEF) and LV radial strain improved numerically following de-banding; however, both measurements remained significantly depressed in the HF-DB mice compared to sham, and were not significantly different from HF mice at 6wks. Reverse LV remodeling in the HF-DB mouse hearts was accompanied by a partial (80%) normalization of the genes that became dysregulated during LV remodeling, whereas 20% of genes remained persistently dysregulated following reverse LV remodeling.
Project description:Wild type, female, C57BL/6 mice were subjected to sham (n=6) surgery, or TAC + MI to cause progressive LV remodeling (n=13). At 2wks post-TAC, one group of mice underwent de-banding (HF-DB, n=6), whereas in a second group of mice the band remained intact (HF_shDB; n = 7). LV remodeling was evaluated by 2D echocardiography at 14 days post-TAC+MI , and 2 wks post-debanding. At 4 wks the hearts were excised and analyzed for changes in gene expression using transcriptional profiling.
Project description:In this project we explore the role of the master hypoxia regulator, Hypoxia inducible factor-1alpha (Hif-1a), in governing cardiac fibroblast (CF) function in homeostasis and following an acute ischaemic injury - myocardial infarction (MI). CF-specific Hif-1a conditional knockout (cKO) mice were generated by breeding Pdgfra-merCremer (PdgfraMCM/+) Cre recombinase driver mice with Hif-1a-floxed mice (Hif-1aflox/). In Hif-1afl/-; PdgfraMCM/+ progeny, Hif-1a could be conditionally deleted in adult CFs by tamoxifen (tam) administration. We also introduced a Cre-dependent R26tdTomato reporter allele allowing marking of Pdgfra+ CFs and their progeny. In this experiment, we first performed single-cell RNA sequencing (scRNA-seq) on tdTomato+ cells from the hearts of healthy cKO or heterozygous (HET) adult, male mice using the 10x Genomics Chromium system. We also performed scRNA-seq on tdTomato+/CD31-/CD45- cells from the hearts of cKO or HET mice at day-3 post-sham or -MI surgery.
Project description:Sexual dimorphisms are well recognized in various cardiac diseases, including myocardial infarction (MI). MI develops later in women, but once established, it contributes more persistent symptoms and higher mortality than in men. Although mRNA-level sexual dimorphism of MI have been reported, whether miRNA transcriptome also confers such dimorphism remains unknown. Comprehensive understanding of the mRNA- and miRNA-level genetic programs underlying the heart sexual dimorphisms will expectedly improve clinical outcome by facilitating the development of gender specific treatment strategies. Here, by conducting miRNA microarray analysis of human MI samples, we set out to characterize the heart sexual dimorphisms at the level of miRNA transcriptome Human tissue samples, acquired during post-mortem examination and frozen in liquid nitrogen, were provided by the department of pathology, Tokyo Metropolitan Geriatric Hospital after the approval from the ethical committee. Age- and sex-matched cohorts were selected to compare healthy hearts to those with post-MI LV remodeling. Border zone for myocardial infarction was sampled. Total RNA was extracted using Sepasol solution (Sepasol-RNA I super G, nakalai tesque, Japan), and microarray analysis was performed using Affymetrix GeneChip® miRNA 3.0 Arrays
Project description:We developed in vivo reprogramming of myofibroblasts (MFs) into induced hepatocytes (MF-iHeps) using adeno-associated virus serotype 6 (AAV6) vectors expressing hepatic transcription factors in MF fate tracing (Lrat-Cre;R26R-ZsGreen) mice with carbon tetrachloride (CCl4)-induced liver fibrosis. To determine whether MF-iHeps acquire full hepatocyte differentiation, we used microarrays to profile their global gene expression. We isolated MF-iHeps and primary hepatocytes (Heps) from the same mice by laser-capture microdissection (5 and 3 biological replicates, respectively) and hepatic MFs from CCl4-treated littermates isolated by fluorescence-activated cell sorting (3 biological replicates). Total RNA was extracted, transcribed, amplified and biotin labeled. Labeled cDNA targets were hybridized to GeneChip Mouse Gene 1.0 ST arrays (Affymetrix).
Project description:The Murphy Roth Large (MRL) mouse, a strain capable of regenerating right ventricular myocardium, has a high post-myocardial infarction (MI) survival rate compared with C57BL6/J (C57) mice. The biological processes responsible for this survival advantage are unknown. We compared acute post-MI gene expression in C57 and MRL hearts using microarrays and identified promising candidate biological processes underlying increased survival in the MRL. Hearts from both strains were excised at different time points before or after MI for RNA extraction and hybridization to MOE430A arrays. Baseline hearts were excised from healthy mice that had not undergone the MI procedure (day 0). Infarct tissue in this case means tissue taken from the anterior-apical region that would be the infarct region in a post-MI heart. Non-infarct covers the remainder of the LV. Post-MI hearts were excised either 1 or 5 days after MI. We had successful hybridizations for 3 replicates each of C57 day 0 infarct and non-infarct tissue (6 arrays), 4 MRL day 0 infarct and non-infarct tissue (8 arrays), 4 C57 day 1 infarct and non-infarct tissue (8 arrays), 4 MRL day 1 infarct and non-infarct tissue (8 arrays), 4 C57 day 5 infarct and non-infarct tissue (8 arrays), and 4 MRL day 5 infarct and non-infarct tissue (8 arrays).
Project description:Myocardial infarction (MI) is the leading cause for hear failure (HF). Following MI, the non-infarcted region of left ventricle (LV) is critical for maintaining heart function, and disruption of the LV contributes greatly to post-MI HF. Transcriptomic profiling by high-throughput sequencing was performed in a chronic HF pig model, to explore the molecular changes in the post-MI LV related to cardiovascular deterioration. Samples were taken from heart tissue of MI-induced pigs and from control pigs not subjected to MI. Regions of the heart where samples were taken included the site of ischemia (LV ischemia), area bordering ischemia (LV border), area remote to ischemia (LV remote) and the right ventricle (RV).
Project description:We developed in vivo reprogramming of myofibroblasts (MFs) into induced hepatocytes (MF-iHeps) using adeno-associated virus serotype 6 (AAV6) vectors expressing hepatic transcription factors in MF fate tracing (Lrat-Cre;R26R-ZsGreen) mice with carbon tetrachloride (CCl4)-induced liver fibrosis. To determine whether MF-iHeps acquire full hepatocyte differentiation, we used microarrays to profile their global gene expression.
Project description:Myocardial infarction (MI) often results in left ventricular (LV) remodeling followed by heart failure (HF). It is of great clinical importance to understand the molecular mechanisms that trigger transition from compensated LV injury to HF and to identify relevant diagnostic biomarkers. In this study, we performed transcriptional profiling of LVs in rats with a wide range of experimentally induced infarct sizes and of peripheral blood mononuclear cells (PBMCs) in animals that developed HF. We used microarrays to investigate gene expression in the left ventricle (LV) accompanying myocardial infarction and concomitant heart failure (HF) in a well validated model of post-infarcted heart failure and to evaluate their reflection in peripheral blood mononuclear cells (PBMCs) Myocardial infarction (MI) was induced in male Wistar rats by ligation of the proximal left coronary artery. The sham-operated group (control group) was subjected to the same protocol, except that the suture was not tied around the proximal left coronary artery. Sham-operated rats (n=6) and rats with small (n=6), moderate (n=6), and large (n=5) MI size were included into the experiment two months after the operation. Then, left ventricules and blood samples were obtained for RNA extraction and hybridization on Affymetrix microarrays. Microarrays were used to compare the LV and PBMCs transcriptomes of control and experimental animals. The development of heart failure was estimated by echocardiography and catheterization.
Project description:Background. Accumulation of extracellular matrix in the myocardium attenuates cardiac contractile function, and predisposes to arrhythmias and sudden cardiac death. Connective tissue growth factor (CTGF) is a matricellular protein that has been shown to promote development of cardiac fibrosis. Objectives. To investigate for the potential of CTGF monoclonal antibody (CTGF mAb) in protecting from development of cardiac fibrosis following myocardial infarction (MI), and to evaluate its effect during infarct repair and acute cardiac ischemia-reperfusion (I/R) injury. Methods. Mice were subjected to MI or to I/R injury and treated with either control IgG or CTGF mAb. Cultured human cardiac fibroblasts were used to investigate the signalling mechanisms modulated by CTGF mAb. Results. Treatment with CTGF mAb for four days from day three after MI improved survival, attenuated infarct expansion, and resulted in better preserved left ventricular (LV) systolic function. CTGF mAb therapy for six weeks from day seven after MI reduced the MI-induced increase in cardiomyocyte size, heart weight to body weight ratio and remote LV fibrosis. RNA sequencing analysis of LV samples showed that CTGF mAb induced expression of cardiac repair/developmental genes and normalized the MI-induced increase in expression of inflammatory/profibrotic genes. CTGF mAb induced c-Jun N-terminal kinase (JNK) phosphorylation in vivo and in vitro, and inhibition of JNK abrogated the reduced collagen production in CTGF mAb treated fibroblasts. Conclusions. Treatment with CTGF mAb induces expression of cardiac repair/developmental genes and inhibits expression of inflammatory/pro-fibrotic genes in MI hearts providing benefit during post-MI cardiac repair and reducing post-MI cardiac fibrosis.