Valérie Metzinger-Le Meuth

miR-143 and miR-145 Molecular Keys to Switch the Phenotype of Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) are able to perform both contractile and synthetic functions, which are associated with changes in morphology, proliferation, and migration rates and are characterized by the specific expression of different marker proteins. Under normal physiological conditions, VSMC rarely proliferate in adult tissues, but undergo major phenotypic changes from the contractile to the synthetic in response to environmental cues, a phenomenon known as switching, or phenotypic modulation.1,2 Phenotypic switching is accompanied by production of abundant cytokines, extracellular matrix, and an increased rate of proliferation and migration. Therefore, the transition of VSMCs from a differentiated phenotype to a dedifferentiated state plays a critical role in the pathogenesis of cardiovascular diseases such as hypertension, vascular injury, and arteriosclerosis.2,3 However, the molecular mechanisms involved in phenotypic switching remain elusive. The last decade has witnessed an exciting discovery that led to a revolution in our understanding of the extensive regulatory gene expression networks modulated by small, untranslated RNAs, microRNAs (miRNAs).4 miRNAs comprise a novel class of endogenous, small RNAs of ≈20 to 25 nucleotides. Although the mature miRNA is very small, it is derived from a transcriptional product of a few hundred to a few thousand nucleotides. This process of maturation is known as miRNA biogenesis, extensively reviewed by Kim.5 Biogenesis of miR-143 and miR-145 is pictorially presented in Figure 1. Functionally, miRNAs are noncoding RNAs that negatively regulate gene expression. In the current, generally accepted model, they act mostly by inducing an inhibition of the translation of their target mRNAs, and, in a minority of cases, via their degradation.6,7 Very recently, however, Bartels team challenged this view by showing that, in a vast majority of cases, mammalian microRNAs act by destabilizing their target mRNAs and decreasing their levels. …

miR-223: An inflammatory oncomiR enters the cardiovascular field.

MicroRNAs (miRNAs) are small, noncoding RNAs of 18-22 nucleotides in length that regulate post-transcriptional expression by base-pairing with target mRNAs. It is now clearly established that miRNAs are involved in most of the cells physiopathological processes (including carcinogenesis and metabolic disorders). This review focuses on miR-223, which was first described as a modulator of hematopoietic lineage differentiation. We outline the role of miR-223 deregulation in several types of cancers and highlight its inclusion in a newly identified and fast-growing family of miRNAs called oncomiRs. We then look at miR-223s emerging role in inflammatory and metabolic disorders, with a particular focus on muscle diseases, type II diabetes, atherosclerosis and vascular calcification. miR-223 is one of the growing number of RNA biomarkers of various human metabolic diseases and is thus of special interest to both researchers and clinicians in the cardiovascular field.

Inorganic phosphate accelerates the migration of vascular smooth muscle cells: evidence for the involvement of miR-223.

Backgound An elevated serum inorganic phosphate (Pi) level is a major risk factor for kidney disease and downstream vascular complications. We focused on the effect of Pi levels on human aortic vascular smooth muscle cells (VSMCs), with an emphasis on the role of microRNAs (miRNAs). Methodology/Principal Findings Exposure of human primary VSMCs in vitro to pathological levels of Pi increased calcification, migration rate and concomitantly reduced cell proliferation and the amount of the actin cytoskeleton. These changes were evidenced by significant downregulation of miRNA-143 (miR-143) and miR-145 and concomitant upregulation of their targets and key markers in synthetic VSMCs, such as Krüppel-like factors−4 and −5 and versican. Interestingly, we also found that miR-223 (a marker of muscle damage and a key factor in osteoclast differentiation) is expressed in VSMCs and is significantly upregulated in Pi-treated cells. Over-expressing miR-223 in VSMCs increased proliferation and markedly enhanced VSMC migration. Additionally, we found that the expression of two of the known miR-223 targets, Mef2c and RhoB, was highly reduced in Pi treated as well as miR-223 over-expressing VSMCs. To complement these in vitro findings, we also observed significant downregulation of miR-143 and miR-145 and upregulation of miR-223 in aorta samples collected from ApoE knock-out mice, which display vascular calcification. Conclusions/Significance Our results suggest that (i) high levels of Pi increase VSMC migration and calcification, (ii) altered expression levels of miR-223 could play a part in this process and (iii) miR-223 is a potential new biomarker of VSMC damage.

Possible involvement of microRNAs in vascular damage in experimental chronic kidney disease

Chronic kidney disease (CKD) is associated with vascular calcifications and atherosclerosis. There is a need for novel predictors to allow earlier diagnosis of these disorders, predict disease progression, and improve assessment of treatment response. We focused on microRNAs since they are implicated in a variety of cellular functions in cardiovascular pathology. We examined changes of microRNA expression in aortas of CKD and non-CKD wild type mice and apolipoprotein E knock-out mice, respectively. Both vascular smooth muscle-specific miR-143 and miR-145 expressions were decreased in states of atherosclerosis and/or CKD or both, and the expression level of protein target Myocardin was increased. The inflammatory miR-223 was increased in more advanced stages of CKD, and specific protein targets NFI-A and GLUT-4 were dramatically decreased. Expression of miR-126 was markedly increased and expression of protein targets VCAM-1 and SDF-1 was altered during the course of CKD. The drug sevelamer, commonly used in CKD, corrected partially these changes in microRNA expression, suggesting a direct link between the observed microRNA alterations and uremic vascular toxicity. Finally, miR-126, -143 and -223 expression levels were deregulated in murine serum during the course of experimental CKD. In conclusion, these miRNAs could have role(s) in CKD vascular remodeling and may therefore represent useful targets to prevent or treat complications of CKD.

miR-126 Is Involved in Vascular Remodeling under Laminar Shear Stress

Morphology and changes in gene expression of vascular endothelium are mainly due to shear stress and inflammation. Cell phenotype modulation has been clearly demonstrated to be controlled by small noncoding micro-RNAs (miRNAs). This study focused on the effect of laminar shear stress (LSS) on human endothelial cells (HUVECs), with an emphasis on the role of miRNA-126 (miR-126). Exposure of HUVECs in vitro to LSS modified the shape of HUVECs and concomitantly regulated the expression of miR-126, vascular cell adhesion molecule 1 (VCAM-1), and syndecan-4 (SDC-4). A significant upregulation of miR-126 during long-term exposure to flow was shown. Interestingly, LSS enhanced SDC-4 expression on the HUVEC membranes. Overexpression of miR-126 in HUVECs decreased the levels of targets stromal cell-derived factor-1 SDF-1/CXCL12 and VCAM-1 but increased the expression of RGS16, CXCR4, and SDC-4. No significant difference in terms of cell proliferation and apoptosis was observed between scramble, anti-miR-126, and pre-miR-126 transfected HUVECs. In Apo-E KO/CKD mice aortas expressing a high level of miR-126, SDC-4 was concomitantly increased. In conclusion, our results suggest that miR-126 (i) is overexpressed by long-term LSS, (ii) has a role in up- and downregulation of genes involved in atherosclerosis, and (iii) affects SDC-4 expression.

The mir-221/222 Cluster is a Key Player in Vascular Biology via the Fine-Tuning of Endothelial Cell Physiology

The discovery of small RNAs has shed new light on microRNA (mRNA) regulation and a range of biological processes. The recognition that miRNAs-221 and -222 are sensitive regulators in the endothelium may enable the identification of novel biomarkers and therapeutic targets. Given that endothelial dysfunction precedes the development of atherosclerosis and contributes to the development of cardiovascular damage, circulating miRNAs produced by Endothelial Cells (ECs) are putative biomarkers for a wide range of cardiovascular diseases. Furthermore, EC proliferation and migration have a critical role in the formation of new blood vessels (angiogenesis), an important component of physiological processes and tumour growth. Hence, the use of anti-angiogenic miRNAs might constitute a novel therapeutic strategy. Along with endothelial angiogenesis, several other processes involving ECs (such as neointimal lesion formation, vascular inflammation, lipoprotein metabolism and hypertension) are critical factors in atherogenesis and atherosclerosis. The fact that human blood-derived progenitor cells, endothelial progenitor cells, umbilical vein ECs and quiescent ECs express high levels of miR-221/222 suggests an important role for this miRNA cluster in endothelial (patho) physiology. The present article reviews current knowledge on miRNAs-221/222s regulation roles in endothelial function and disease in general and angiogenesis in particular.

microRNAs in the pathophysiology of CKD-MBD: Biomarkers and innovative drugs.

microRNAs comprise a novel class of endogenous small non-coding RNAs that have been shown to be implicated in both vascular damage and bone pathophysiology. Chronic kidney disease-mineral bone disorder (CKD-MBD) is characterized by vessel and bone damage secondary to progressive loss of kidney function. In this review, we will describe how several microRNAs have been implicated, in recent years, in cellular and animal models of CKD-MBD, and have been very recently shown to be deregulated in patients with CKD. Particular emphasis has been placed on the endothelial-specific miR-126, a potential biomarker of endothelial dysfunction, and miR-155 and miR-223, which play a role in both vascular smooth muscle cells and osteoclasts, with an impact on the vascular calcification and osteoporosis process. Finally, as these microRNAs may constitute useful targets to prevent or treat complications of CKD-MBD, we will discuss their potential as innovative drugs, describe how they could be delivered in a timely and specific way to vessels and bone by using the most recent techniques such as nanotechnology, viral vectors or CRISPR gene targeting.

Is there adaptation of the exocrine pancreas in wild animal? The case of the Roe Deer

BackgroundPhysiology of the exocrine pancreas has been well studied in domestic and in laboratory animals as well as in humans. However, it remains quite unknown in wildlife mammals. Roe deer and cattle (including calf) belong to different families but have a common ancestor. This work aimed to evaluate in the Roe deer, the adaptation to diet of the exocrine pancreatic functions and regulations related to animal evolution and domestication.ResultsForty bovine were distributed into 2 groups of animals either fed exclusively with a milk formula (monogastric) or fed a dry feed which allowed for rumen function to develop, they were slaughtered at 150 days of age. The 35 Roe deer were wild animals living in the temperate broadleaf and mixed forests, shot during the hunting season and classified in two groups adult and young. Immediately after death, the pancreas was removed for tissue sample collection and then analyzed. When expressed in relation to body weight, pancreas, pancreatic protein weights and enzyme activities measured were higher in Roe deer than in calf. The 1st original feature is that in Roe deer, the very high content in pancreatic enzymes seems to be related to specific digestive products observed (proline-rich proteins largely secreted in saliva) which bind tannins, reducing their deleterious effects on protein digestion. The high chymotrypsin and elastase II quantities could allow recycling of proline-rich proteins. In contrast, domestication and rearing cattle resulted in simplified diet with well digestible components. The 2nd feature is that in wild animal, both receptor subtypes of the CCK/gastrin family peptides were present in the pancreas as in calf, although CCK-2 receptor subtype was previously identified in higher mammals.ConclusionsBovine species could have lost some digestive capabilities (no ingestion of great amounts of tannin-rich plants, capabilities to secrete high amounts of proline-rich proteins) compared with Roe deer species. CCK and gastrin could play an important role in the regulation of pancreatic secretion in Roe deer as in calf. This work, to the best of our knowledge is the first study which compared the Roe deer adaptation to diet with a domesticated animal largely studied.

MicroRNAs Are Associated with Uremic Toxicity, Cardiovascular Calcification, and Disease

BACKGROUND Vascular calcification has been recognized to be a major risk factor in chronic kidney disease (CKD) and downstream cardiovascular complications. Micro-RNAs (miRNAs) are small noncoding RNAs comprising 20-25 nucleotides that regulate gene expression by inhibiting or degrading the target mRNA, and constitute potential new biomarkers and future therapeutic strategies. SUMMARY We tested the relevance of several cardiovascular-specific miRNAs as new biomarkers for CKD, cardiovascular disease, and cardiovascular complications. We have shown, in murine models, that miR-126, miR-143, miR-145, and miR-223 levels and the levels of their specific targets are modulated during the crucial stages of CKD and atherosclerosis. In addition, miRNA levels were correlated with classical biomarkers of CKD and atherosclerosis such as cholesterol, urea, and calcium levels. Dysregulation of these same miRNAs was observed in the serum of CKD, hemodialyzed, and kidney transplant recipients. We also demonstrated correlations between serum miRNAs and uremic toxins. We therefore suggest that miR-126, miR-143, miR-145, and miR-223 are potential biomarkers of vascular calcification and cardiovascular disease associated with CKD. Key Messages: The identification of new biomarkers that can improve the diagnosis and monitoring of CKD and cardiovascular disease patients is crucial in modern medicine. Our data could be particularly useful in the management of cardiovascular disease associated with CKD, provide new light in the understanding of the molecular events underlying cardiovascular disease and cardiovascular calcification, and possibly be used as a treatment strategy to prevent these diseases.

The Involvement of miRNA in Carotid-Related Stroke

Cardiovascular disease is the leading cause of morbidity and mortality in developed countries. Stroke is associated with a marked disability burden and has a major economic impact; this is especially true for carotid artery stroke. Major advances in primary and secondary prevention during the last few decades have helped to tackle this public health problem. However, better knowledge of the physiopathology of stroke and its underlying genetic mechanisms is needed to improve diagnosis and therapy. miRNAs are an important, recently identified class of post-transcriptional regulators of gene expression and are known to be involved in cerebrovascular disease. These endogenous, small, noncoding RNAs may have applications as noninvasive biomarkers and therapeutic tools in practice. Here, we review the involvement of several miRNAs in cell-based and whole-animal models of stroke, with a focus on human miRNA profiling studies of carotid artery stroke. Lastly, we describe the miRNAs’ potential role as a biomarker of stroke.