Clarice Gareri

Down-regulation of miR-23b induces phenotypic switching of vascular smooth muscle cells in vitro and in vivo

AIMS Phenotypic switch of vascular smooth muscle cells (VSMCs) plays a key role in the pathogenesis of different vascular diseases, such as atherosclerosis and restenosis after coronary intervention. MicroRNAs have been identified as key regulators of VSMC biology. The miR-23b is highly expressed in VSMCs and it is involved in differentiation, proliferation, and migration of several non-vascular cell types. However, the role of miR-23b in vascular disease is currently unknown. Thus, the aim of the present study was to evaluate the role of miR-23b on VSMC phenotypic switch in vitro and after vascular injury in vivo. METHODS AND RESULTS To determine the changes of miR-23b expression in the injured arterial wall, we used the standard rat carotid artery balloon injury model. In vivo studies demonstrated that miR-23b is down-regulated after vascular injury. Gain-of-function studies showed that overexpression of miR-23b inhibited VSMC proliferation and migration, whereas the opposite effect was obtained with the in vitro inhibition of miR-23b. We further demonstrated that miR-23b can significantly promote the expression of VSMC marker genes such as smooth muscle α-actin (ACTA2) and smooth muscle myosin heavy chain (MYH11). Overexpression of miR-23b in balloon-injured arteries by Ad-miR-23b markedly decreased neointimal hyperplasia. Finally, miR-23b specifically suppresses urokinase-type plasminogen activator, SMAD family member 3, and transcription factor forkhead box O4 (FoxO4) expression in phenotypically modulated VSMCs. By luciferase reporter assay, we validated the transcription factor FoxO4 as a direct target of miR-23b in VSMCs. CONCLUSIONS We identify miR-23b as a novel regulator of VSMC phenotypic switch in vitro and following vascular injury in vivo.

Non-Coding RNAs: The “Dark Matter” of Cardiovascular Pathophysiology

Large-scale analyses of mammalian transcriptomes have identified a significant number of different RNA molecules that are not translated into protein. In fact, the use of new sequencing technologies has identified that most of the genome is transcribed, producing a heterogeneous population of RNAs which do not encode for proteins (ncRNAs). Emerging data suggest that these transcripts influence the development of cardiovascular disease. The best characterized non-coding RNA family is represented by short highly conserved RNA molecules, termed microRNAs (miRNAs), which mediate a process of mRNA silencing through transcript degradation or translational repression. These microRNAs (miRNAs) are expressed in cardiovascular tissues and play key roles in many cardiovascular pathologies, such as coronary artery disease (CAD) and heart failure (HF). Potential links between other ncRNAs, like long non-coding RNA, and cardiovascular disease are intriguing but the functions of these transcripts are largely unknown. Thus, the functional characterization of ncRNAs is essential to improve the overall understanding of cellular processes involved in cardiovascular diseases in order to define new therapeutic strategies. This review outlines the current knowledge of the different ncRNA classes and summarizes their role in cardiovascular development and disease.

Carbonic Anhydrase Activation Is Associated With Worsened Pathological Remodeling in Human Ischemic Diabetic Cardiomyopathy

Background Diabetes mellitus (DM) has multifactorial detrimental effects on myocardial tissue. Recently, carbonic anhydrases (CAs) have been shown to play a major role in diabetic microangiopathy but their role in the diabetic cardiomyopathy is still unknown. Methods and Results We obtained left ventricular samples from patients with DM type 2 (DM‐T2) and nondiabetic (NDM) patients with postinfarct heart failure who were undergoing surgical coronary revascularization. Myocardial levels of CA‐I and CA‐II were 6‐ and 11‐fold higher, respectively, in DM‐T2 versus NDM patients. Elevated CA‐I expression was mainly localized in the cardiac interstitium and endothelial cells. CA‐I induced by high glucose levels hampers endothelial cell permeability and determines endothelial cell apoptosis in vitro. Accordingly, capillary density was significantly lower in the DM‐T2 myocardial samples (mean±SE=2152±146 versus 4545±211/mm2). On the other hand, CA‐II was mainly upregulated in cardiomyocytes. The latter was associated with sodium‐hydrogen exchanger‐1 hyperphosphorylation, exaggerated myocyte hypertrophy (cross‐sectional area 565±34 versus 412±27 μm2), and apoptotic death (830±54 versus 470±34 per 106 myocytes) in DM‐T2 versus NDM patients. CA‐II is activated by high glucose levels and directly induces cardiomyocyte hypertrophy and death in vitro, which are prevented by sodium‐hydrogen exchanger‐1 inhibition. CA‐II was shown to be a direct target for repression by microRNA‐23b, which was downregulated in myocardial samples from DM‐T2 patients. MicroRNA‐23b is regulated by p38 mitogen‐activated protein kinase, and it modulates high‐glucose CA‐II–dependent effects on cardiomyocyte survival in vitro. Conclusions Myocardial CA activation is significantly elevated in human diabetic ischemic cardiomyopathy. These data may open new avenues for targeted treatment of diabetic heart failure.

Transcoronary concentration gradients of circulating microRNAs in heart failure: Transcoronary gradients of miRNAs in HF

Circulating levels of microRNAs (miRNAs) are emergent promising biomarkers for cardiovascular disease. Altered expression of miRNAs has been related to heart failure (HF) and cardiac remodelling. We measured the concentration gradients across the coronary circulation to assess their usefulness to diagnose HF of different aetiologies.

Non-coding RNAs in vascular remodeling and restenosis

Vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) are crucial in vascular remodeling. They exert pivotal roles in the development and progression of atherosclerosis, vascular response to injury, and restenosis after transcatheter angioplasty. As a witness of their importance in the cardiovascular system, a large body of evidence has accumulated about the role played by micro RNAs (miRNA) in modulating both VSMCs and ECs. More recently, a growing number of long noncoding RNA (lncRNAs) came beneath the spotlights in this research field. Several mechanisms have been revealed by which lncRNAs are able to exert a relevant biological impact on vascular remodeling. The aim of this review is to provide an integrated summary of ncRNAs that exert a relevant biological function in VSMCs and ECs of the vascular wall, with emphasis on the available clinical evidence of the potential usefulness of these molecules as circulating biomarkers of in-stent restenosis.