Inhibition of MicroRNA-125a Promotes Human Endothelial Cell Proliferation and Viability through an Antiapoptotic Mechanism.

The microRNA-125a (miR-125a) is highly expressed in endothelial cells, but its role in vascular biology is not known. Endothelial cell proliferation and viability play an important role in endothelial healing, and we hypothesize that miR-125a regulates this process. The aim of the present study was to investigate if miR-125a controls human endothelial cell proliferation, viability and endothelial healing, and to assess the mechanisms involved. We showed that overexpression of miR-125a by transfection with miR-125a mimic reduced human umbilical vein endothelial cell (HUVEC) proliferation and viability, and stimulated apoptosis as demonstrated by a miR-125a-induced increase of the proportion of annexin V-positive cells monitored by flow cytometry. Moreover, we showed that the miR-125a mimic downregulated the antiapoptotic Bcl2 protein and upregulated caspase 3, suggesting that these two proteins represent molecular targets for miR-125a. Accordingly, transfection with miR-125a inhibitor, downregulating miR-125a expression, promoted HUVEC proliferation and viability, and reduced apoptosis. Importantly, transfection with miR-125a inhibitor promoted HUVEC tube formation in Matrigel, suggesting that reduction of miR-125a has a proangiogenic effect. In conclusion, downregulation of miR-125a through local transfection with miR-125a inhibitor might be a new way to enhance endothelial cell proliferation and viability, thereby promoting the reendothelialization observed in response to intimal injury. © 2014 S. Karger AG, Basel

Circulating cardio-enriched microRNAs are associated with long-term prognosis following myocardial infarction.

Increased levels of cardio-enriched microRNAs (miRNAs) have been described in patients with myocardial infarction (MI). We wanted to evaluate the diagnostic and prognostic potential of cardio-enriched miRNAs in patients presenting with a suspected acute coronary syndrome (ACS)

Platelets activated during myocardial infarction release functional miRNA which can be taken up by endothelial cells and regulate ICAM1 expression.

Key points Myocardial infarction patients have altered platelet miRNA profilesActivated platelets release miRNAs that can be taken up by endothelial cells and regulate ICAM1 gene expression

The brain-enriched microRNA miR-124 in plasma predicts neurological outcome after cardiac arrest

Introduction: Early prognostication after successful cardiopulmonary resuscitation is difficult, and there is a need for novel methods to estimate the extent of brain injury and predict outcome. In this study, we evaluated the impact of the cardiac arrest syndrome on the plasma levels of selected tissue-specific microRNAs (miRNAs) and assessed their ability to prognosticate death and neurological disability. Methods: We included 65 patients treated with hypothermia after cardiac arrest in the study. Blood samples were obtained at 24 hours and at 48 hours. For miRNA-screening purposes, custom quantitative polymerase chain reaction (qPCR) panels were first used. Thereafter individual miRNAs were assessed at 48 hours with qPCR. miRNAs that successfully predicted prognosis at 48 hours were further analysed at 24 hours. Outcomes were measured according to the Cerebral Performance Category (CPC) score at 6 months after cardiac arrest and stratified into good (CPC score 1 or 2) or poor (CPC scores 3 to 5). Results: At 48 hours, miR-146a, miR-122, miR-208b, miR-21, miR-9 and miR-128 did not differ between the good and poor neurological outcome groups. In contrast, miR-124 was significantly elevated in patients with poor outcomes compared with those with favourable outcomes (P < 0.0001) at 24 hours and 48 hours after cardiac arrest. Analysis of receiver operating characteristic curves at 24 and 48 hours after cardiac arrest showed areas under the curve of 0.87 (95% confidence interval (CI) = 0.79 to 0.96) and 0.89 (95% CI = 0.80 to 0.97), respectively. Conclusions: The brain-enriched miRNA miR-124 is a promising novel biomarker for prediction of neurological prognosis following cardiac arrest

5′UTR Variants of Ribosomal Protein S19 Transcript Determine Translational Efficiency: Implications for Diamond-Blackfan Anemia and Tissue Variability

Background: Diamond-Blackfan anemia (DBA) is a lineage specific and congenital erythroblastopenia. The disease is associated with mutations in genes encoding ribosomal proteins resulting in perturbed ribosomal subunit biosynthesis. The RPS19 gene is mutated in approximately 25 % of DBA patients and a variety of coding mutations have been described, all presumably leading to haploinsufficiency. A subset of patients carries rare polymorphic sequence variants within the 59untranslated region (59UTR) of RPS19. The functional significance of these variants remains unclear. Methodology/Principal Findings: We analyzed the distribution of transcriptional start sites (TSS) for RPS19 mRNAs in testis and K562 cells. Twenty-nine novel RPS19 transcripts were identified with different 59UTR length. Quantification of expressed w.t. 59UTR variants revealed that a short 59UTR correlates with high levels of RPS19. The total levels of RPS19 transcripts showed a broad variation between tissues. We also expressed three polymorphic RPS19 59UTR variants identified in DBA patients. The sequence variants include two insertions (c.-147_-146insGCCA and c.-147_-146insAGCC) and one deletion (c.-144_-141delTTTC). The three 59UTR polymorphisms are associated with a 20–30 % reduction in RPS19 protein levels when compared to the wild-type (w.t.) 59UTR of corresponding length. Conclusions: The RPS19 gene uses a broad range of TSS and a short 59UTR is associated with increased levels of RPS19. Comparisons between tissues showed a broad variation in the total amount of RPS19 mRNA and in the distribution of TS

A Common Missense Variant in the ATP Receptor P2X7 Is Associated with Reduced Risk of Cardiovascular Events

BACKGROUND AND PURPOSE: Extracellular adenosine triphosphate (ATP) regulates inflammatory cells by activation of the P2X(7) receptor. We hypothesized that polymorphisms in P2RX7 influence the risk of ischemic heart disease (IHD), ischemic stroke (IS) and cardiovascular risk factors and tested this hypothesis using genetic association studies. METHODS: Two loss-of-function SNPs in P2RX7 were genotyped in 1244 IHD cases and 2488 controls as well as 5969 individuals with cardiovascular risk factors. Eleven SNPs in a 250 kb region on chromosome 12 spanning P2RX7 as well as neighboring genes OASL, P2RX4 and CAMKK2 were genotyped in 4138 individuals with IS and 2528 controls. Association was examined using linear and logistic regression models with an additive genetic model. RESULTS: The common loss-of-function variant rs3751143 was significantly associated with a decreased risk of IHD in smokers (P = 0.03) as well as decreased risk of IS (OR 0.89; 95% CI = 0.81-0.97; P = 0.012). In addition, an intronic SNP in CAMKK2, rs2686342, were associated with a decreased risk of IS (OR 0.89; 95% CI = 0.82-0.97; P = 0.011). In subgroup analyses, both SNPs were associated with decreased risk of IS in individuals with hypertension (P = 0.045 and 0.015, respectively). CONCLUSIONS: A common loss-of-function missense variant in the gene encoding the P2X(7) receptor is associated with reduced risk of IS and with IHD in smokers. These findings might implicate a role of purinergic signaling in atherogenesis or atherothrombosis

Discovery of Genetic Variation on Chromosome 5q22 Associated with Mortality in Heart Failure

Failure of the human heart to maintain sufficient output of blood for the demands of the body, heart failure, is a common condition with high mortality even with modern therapeutic alternatives. To identify molecular determinant

Clinical and Biological Aspects of Cardiovascular microRNA

Ischemic heart disease is the leading cause of death in high-income parts of the world and is caused mainly by atherosclerosis in the coronary arteries. The rupture of an atherosclerotic plaque with subsequent platelet activation and clot formation can lead to myocardial infarction (MI). Atherosclerosis is a complex process, which involves the accumulation and oxidation of low-density lipoprotein in the vessel wall followed by endothelial inflammation, infiltration of monocytes and proliferation and migration of vascular smooth muscle cells towards the vessel lumen. microRNA (miRNA) is a class of short non-coding RNA which regulate gene expression through part-complimentary binding to target sites preferably within the 3’-UTR of specific mRNAs. miRNAs have pervasive roles in animal biology and aberrant expression of miRNAs have been linked with a wide spectrum of human disease. Additionally, the tissue specific manner of miRNA expression together with remarkable stability in plasma and evidence of release of miRNA from stressed or apoptotic cells have made miRNAs interesting as biomarkers for various diseases. The aim of this thesis was (1) to assess the diagnostic and prognostic value of cardiac-enriched miRNAs in the context of coronary artery disease, (2) to screen for differences in miRNA content in platelets from myocardial infarction patients and elucidate a potential paracrine function for platelet miRNA and (3) to investigate the role of miRNAs in regulating endothelial inflammation in response to extracellular ATP/UTP. In Study I and II, we found that cardiac-enriched miRNAs are increased 100-3000 fold within 12 h following onset of symptoms in patients with myocardial infarction and that the levels of two specific miRNAs, miR-208b and-499-5p, could be used to discriminate MI-patients from non-MI patients and were associated with increased risk of death and development of heart failure. In Study III, we found differentially expressed platelet miRNAs in MI patients compared to healthy controls using RNA-sequencing. Release of miRNAs upon platelet activation, as well as microparticle-dependent transfer of functional platelet-derived miRNA to endothelial cells was also shown in vitro. In Study IV, we showed that the effects of ATP and UTP on cell surface expression of intercellular adhesion molecule 1 (ICAM-1) and leukocyte adhesion is mediated in part by miR-22 in endothelial cells. In conclusion, the levels of circulating cardiac-enriched miRNA have diagnostic and prognostic value in the context of coronary artery disease, platelet-derived miRNA can act as paracrine mediators in endothelial cells and miR-22 plays an anti-inflammatory role in the endothelium

Toward a New Paradigm for Targeted Natriuretic Peptide Enhancement in Heart Failure

The natriuretic peptide system (NPS) plays a fundamental role in maintaining cardiorenal homeostasis, and its potent filling pressure-regulated diuretic and vasodilatory effects constitute a beneficial compensatory mechanism in heart failure (HF). Leveraging the NPS for therapeutic benefit in HF has been the subject of intense investigation during the last three decades and has ultimately reached widespread clinical use in the form of angiotensin receptor-neprilysin inhibition (ARNi). NPS enhancement via ARNi confers beneficial effects on mortality and hospitalization in HF, but inhibition of neprilysin leads to the accumulation of a number of other vasoactive peptides in the circulation, often resulting in hypotension and raising potential concerns over long-term adverse effects. Moreover, ARNi is less effective in the large group of HF patients with preserved ejection fraction. Alternative approaches for therapeutic augmentation of the NPS with increased specificity and efficacy are therefore warranted, and are now becoming feasible particularly with recent development of RNA therapeutics. In this review, the current state-of-the-art in terms of experimental and clinical strategies for NPS augmentation and their implementation will be reviewed and discussed

MicroRNAs in the failing heart - Novel therapeutic targets?

Abstract Heart failure is a common and disabling disease with high mortality that carries substantial societal costs. Current therapeutic strategies are aimed at relieving symptoms, avoiding hospitalization, and prolonging life, but disease progression is ultimately inevitable. MicroRNAs (miRNAs) are short, non-coding RNA molecules with pervasive roles in eukaryotic biology, annealing to complimentary sites on target mRNAs, and repressing gene expression. The fact that miRNAs are dysregulated in many human disorders, including cardiovascular disease, and the relative ease with which endogenous miRNA expression can be altered using synthetic antisense oligos has stirred enthusiasm for these molecules as potential drug targets. The aim of this review article was to summarize the current knowledge on the roles of miRNA in the pathophysiology of heart failure as well as the use of miRNAs as therapeutic targets and diagnostic tools for the disease