R-24 inhibits apoptosis and represses Bim in mouse cardiomyocytes. J Exp Med

Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, San Francisco, CA 94143, USA.
Journal of Experimental Medicine (Impact Factor: 12.52). 03/2011; 208(3):549-60. DOI: 10.1084/jem.20101547
Source: PubMed


Acute myocardial infarction (MI) involves necrotic and apoptotic loss of cardiomyocytes. One strategy to salvage ischemic cardiomyocytes is to modulate gene expression to promote cell survival without disturbing normal cardiac function. MicroRNAs (miRNAs) have emerged as powerful regulators of multiple cellular processes, including apoptosis, suggesting that regulation of miRNA function could serve a cardioprotective function. In this study, we report that miR-24 (miRNA-24) expression is down-regulated in the ischemic border zone of the murine left ventricle after MI. miR-24 suppresses cardiomyocyte apoptosis, in part by direct repression of the BH3-only domain-containing protein Bim, which positively regulates apoptosis. In vivo expression of miR-24 in a mouse MI model inhibited cardiomyocyte apoptosis, attenuated infarct size, and reduced cardiac dysfunction. This antiapoptotic effect on cardiomyocytes in vivo was partially mediated by Bim. Our results suggest that manipulating miRNA levels during stress-induced apoptosis may be a novel therapeutic strategy for cardiac disease.

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    • "We performed genome-wide miRNA expression profiling in rat cardiomyoblasts during the conditions of UPR. We found that miRNAs (miR-206, miR-24, miR-125b, miR-133b) with known function in cardiomyoblasts biology [20–22] were significantly deregulated during the conditions of UPR in H9c2 cells. The expression of miR-7a was upregulated by UPR and simulated in vitro ischemia in cardiomyoblasts. "
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    ABSTRACT: Background Glucose and oxygen deprivation during ischemia is known to affect the homeostasis of the endoplasmic reticulum (ER) in ways predicted to activate the unfolded protein response (UPR). Activation of UPR signalling due to ER stress is associated with the development of myocardial infarction (MI). MicroRNAs (miRNAs) are key regulators of cardiovascular development and deregulation of miRNA expression is involved in the onset of many cardiovascular diseases. However, little is known about the mechanisms regulating the miRNA expression in the cardiovascular system during disease development and progression. Here we performed genome-wide miRNA expression profiling in rat cardiomyoblasts to identify the miRNAs deregulated during UPR, a crucial component of ischemia. Results We found that expression of 86 microRNAs changed significantly during conditions of UPR in H9c2 cardiomyoblasts. We found that miRNAs with known function in cardiomyoblasts biology (miR-206, miR-24, miR-125b, miR-133b) were significantly deregulated during the conditions of UPR in H9c2 cells. The expression of miR-7a was upregulated by UPR and simulated in vitro ischemia in cardiomyoblasts. Further, ectopic expression of miR-7a provides resistance against UPR-mediated apoptosis in cardiomyoblasts. The ample overlap of miRNA expression signature between our analysis and different models of cardiac dysfunction further confirms the role of UPR in cardiovascular diseases. Conclusions This study demonstrates the role of UPR in deregulating the expression of miRNAs in MI. Our results provide novel insights about the molecular mechanisms of deregulated miRNA expression during the heart disease pathogenesis.
    Cell and Bioscience 09/2014; 4(1):56. DOI:10.1186/2045-3701-4-56 · 3.63 Impact Factor
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    • "The identification of these regulatory elements is crucial for the development of ASOs that bind to and inhibit cis-acting elements to alter BIM splicing for therapeutic purposes. Increased BIM expression has been shown to contribute to increased cardiomyocyte and neuronal cell death following ischemia [11], [12]. Therefore, a potential therapeutic approach to reduce cell death is to decrease the expression of exon 4-containing BIM transcripts. "
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    ABSTRACT: Aberrant changes in the expression of the pro-apoptotic protein, BCL-2-like 11 (BIM), can result in either impaired or excessive apoptosis, which can contribute to tumorigenesis and degenerative disorders, respectively. Altering BIM pre-mRNA splicing is an attractive approach to modulate apoptosis because BIM activity is partly determined by the alternative splicing of exons 3 or 4, whereby exon 3-containing transcripts are not apoptotic. Here we identified several cis-acting elements and splicing factors involved in BIM alternative splicing, as a step to better understand the regulation of BIM expression. We analyzed a recently discovered 2,903-bp deletion polymorphism within BIM intron 2 that biased splicing towards exon 3, and which also impaired BIM-dependent apoptosis. We found that this region harbors multiple redundant cis-acting elements that repress exon 3 inclusion. Furthermore, we have isolated a 23-nt intronic splicing silencer at the 3' end of the deletion that is important for excluding exon 3. We also show that PTBP1 and hnRNP C repress exon 3 inclusion, and that downregulation of PTBP1 inhibited BIM-mediated apoptosis. Collectively, these findings start building our understanding of the cis-acting elements and splicing factors that regulate BIM alternative splicing, and also suggest potential approaches to alter BIM splicing for therapeutic purposes.
    PLoS ONE 04/2014; 9(4):e95210. DOI:10.1371/journal.pone.0095210 · 3.23 Impact Factor
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    • "Mature miRNAs can form miRNAinduced silencing complexes, which bind to the 3 0 -untranslated region (3 0 UTR) of target mRNAs to mediate translational repression [6]. Previous studies have suggested that miRNAs play important roles in regulating cell apoptosis [7] [8] [9] and the progression of vascular disease [10] [11]. Amongst the various miRNAs, miR-92a is a component of the miR-17-92 cluster, which is highly expressed in human ECs, particularly in young endothelial cells [12]. "
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    ABSTRACT: Oxidative stress contributes to endothelial cell (EC) dysfunction, which is prevalent in ageing and atherosclerosis. MicroRNAs (miRs) are small, non-coding RNAs that post-transcriptionally regulate gene expression and play a key role in fine-tuning EC functional responses, including apoptosis and angiogenesis. MiR-92a is highly expressed in young endothelial cells in comparison with senescent endothelial cells, which exhibit increased oxidative stress and apoptosis. However, the impact of miR-92a treatment on EC viability and angiogenesis under oxidative stress is unknown. Hydrogen peroxide (H2O2) was used to induce oxidative stress in human umbilical vein endothelial cells (HUVEC). Pre-miR-92a treatment decreased H2O2–induced apoptosis of HUVEC as determined by TUNEL assay. Pre-miR-92a treatment enhanced capillary tube formation by HUVEC under oxidative stress, which was blocked by LY294002, an inhibitor of Akt phosphorylation. Interestingly, we also observed that inhibition of miR-92a by anti-miR-92a antisense can also enhance angiogenesis in HUVEC with and without oxidative stress exposure. Our results show that perturbation of miR-92a levels outside of its narrow “homeostatic” range may trigger endothelial cell angiogenesis, suggesting that the role of miR-92a in regulating angiogenesis is controversial and may vary depending on the experimental model and method of regulating miR-92a.
    Biochemical and Biophysical Research Communications 04/2014; 446(4). DOI:10.1016/j.bbrc.2014.03.035 · 2.30 Impact Factor
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