miR-30a regulates endothelial tip cell formation and arteriolar branching

The role of microRNAs in defining LSECs cellular identity and in regulating F8 gene expression

Introduction: Coagulation Factor VIII (FVIII) plays a pivotal role in the coagulation cascade, and deficiencies in its levels, as seen in Hemophilia A, can lead to significant health implications. Liver sinusoidal endothelial cells (LSECs) are the main producers and contributors of FVIII in blood, a fact we have previously elucidated through mRNA expression profiling when comparing these cells to other endothelial cell types. Methods: Our current investigation focuses on small microRNAs, analyzing their distinct expression patterns across various endothelial cells and hepatocytes. Results: The outcome of this exploration underscores the discernible microRNAs expression differences that set LSECs apart from both hepatocytes (193 microRNAs at p < 0.05) and other endothelial cells (72 microRNAs at p < 0.05). Notably, the 134 and 35 overexpressed microRNAs in LSECs compared to hepatocytes and other endothelial cells, respectively, shed light on the unique functions of LSECs in the liver. Discussion: Our investigation identified a panel of 10 microRNAs (miR-429, miR-200b-3p, miR-200a-3p, miR-216b-5p, miR-1185-5p, miR-19b-3p, miR-192-5p, miR-122-5p, miR-30c-2-3p, and miR-30a-5p) that distinctly define LSEC identity. Furthermore, our scrutiny extended to microRNAs implicated in F8 regulation, revealing a subset (miR-122-5p, miR-214-3p, miR-204-3p, and miR-2682-5p) whose expression intricately correlates with F8 expression within LSECs. This microRNA cohort emerges as a crucial modulator of F8, both directly through suppression and indirect effects on established F8-related transcription factors. The above microRNAs emerged as potential targets for innovative therapies in Hemophilia A patients.

Role of cell rearrangement and related signaling pathways in the dynamic process of tip cell selection

Angiogenesis is a complex, highly-coordinated and multi-step process of new blood vessel formation from pre-existing blood vessels. When initiated, the sprouting process is spearheaded by the specialized endothelial cells (ECs) known as tip cells, which guide the organization of accompanying stalk cells and determine the function and morphology of the finally-formed blood vessels. Recent studies indicate that the orchestration and coordination of angiogenesis involve dynamic tip cell selection, which is the competitive selection of cells to lead the angiogenic sprouts. Therefore, this review attempt to summarize the underlying mechanisms involved in tip cell specification in a dynamic manner to enable readers to gain a systemic and overall understanding of tip cell formation, involving cooperative interaction of cell rearrangement with Notch and YAP/TAZ signaling. Various mechanical and chemical signaling cues are integrated to ensure the right number of cells at the right place during angiogenesis, thereby precisely orchestrating morphogenic functions that ensure correct patterning of blood vessels. Video Abstract.

miRNAs driving diagnosis, prognosis and progression in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive form of skin malignancy with a high recurrence commonly within two to three years of initial diagnosis. The incidence of MCC has nearly doubled in the past few decades. Options for diagnosing, assessing, and treating MCC are limited. MicroRNAs (miRNAs) are a class of small, non-coding RNA molecules that play an important role in controlling many different aspects of cell biology. Many miRNAs are aberrantly expressed in distinct types of cancer, with some serving as tumor suppressors and others as oncomiRs. Therefore, the future holds great promise for the utilization of miRNAs in enhancing diagnostic, prognostic, and therapeutic approaches for MCC. Accordingly, the goal of this article is to compile, summarize, and discuss the latest research on miRNAs in MCC, highlighting their potential clinical utility as diagnostic and prognostic biomarkers.

MicroRNA-22 coordinates vascular and motor neuronal pathfinding via sema4 during zebrafish development

A precise guiding signal is crucial to orchestrate directional migration and patterning of the complex vascular network and neural system. So far, limited studies have reported the discovery and functions of microRNAs (miRNAs) in guiding vascular and neural pathfinding. Currently, we showed that the deficiency of miRNA-22a, an endothelial-enriched miRNA, caused dramatic pathfinding defects both in intersegmental vessels (ISVs) and primary motor neurons (PMNs) in zebrafish embryos. Furthermore, we found the specific inhibition of miR-22a in endothelial cells (ECs) resulted in patterning defects of both ISVs and PMNs. Neuronal block of miR-22a mainly led to axonal defects of PMN. Sema4c was identified as a potential target of miR-22a through transcriptomic analysis and in silico analysis. Additionally, a luciferase assay and EGFP sensor assay confirmed the binding of miR-22a with 3'-UTR of sema4c. In addition, downregulation of sema4c in the miR-22a morphants significantly neutralized the aberrant patterning of vascular and neural networks. Then we demonstrated that endothelial miR-22a regulates PMNs axonal navigation. Our study revealed that miR-22a acted as a dual regulatory cue coordinating vascular and neuronal patterning, and expanded the repertoire of regulatory molecules, which might be of use therapeutically to guide vessels and nerves in the relevant diseases.

Interdependence of Angiogenesis and Arteriogenesis in Development and Disease

The structure of arterial networks is optimized to allow efficient flow delivery to metabolically active tissues. Optimization of flow delivery is a continuous process involving synchronization of the structure and function of the microcirculation with the upstream arterial network. Risk factors for ischemic cardiovascular diseases, such as diabetes mellitus and hyperlipidemia, adversely affect endothelial function, induce capillary regression, and disrupt the micro- to macrocirculation cross-talk. We provide evidence showing that this loss of synchronization reduces arterial collateral network recruitment upon arterial stenosis, and the long-term clinical outcome of current revascularization strategies in these patient cohorts. We describe mechanisms and signals contributing to synchronized growth of micro- and macrocirculation in development and upon ischemic challenges in the adult organism and identify potential therapeutic targets. We conclude that a long-term successful revascularization strategy should aim at both removing obstructions in the proximal part of the arterial tree and restoring “bottom-up” vascular communication.

Insight Into the Roles of Non-coding RNA in Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease most commonly occurring in premature infants, and its pathological manifestations are alveolar hypoplasia and dysregulation of pulmonary vasculature development. The effective treatment for BPD has not yet been established. Non-coding RNAs, including microRNAs and long non-coding RNAs do not encode proteins, but can perform its biological functions at the RNA level. Non-coding RNAs play an important role in the incidence and development of BPD by regulating the expression of genes related to proliferation, apoptosis, angiogenesis, inflammation and other cell activities of alveolar epithelial cells and vascular endothelial cells. Here we summarize the role of non-coding RNAs in BPD, which provides possible molecular marker and therapeutic target for the diagnosis and treatment of BPD.

Changing Incidence and Mechanism of Pregnancy-Associated Myocardial Infarction in the State of California

Background The objective of this study was to evaluate the temporal trends in pregnancy-associated myocardial infarction (PAMI) in the State of California and explore potential risk factors and mechanisms. Methods and Results The California State Inpatient Database was analyzed from 2003 to 2011 for patients with International Classification of Diseases, Ninth Revision (ICD-9) codes for acute myocardial infarction and pregnancy or postpartum admissions; risk factors were analyzed and compared with pregnant patients without myocardial infarction. A total of 341 patients were identified with PAMI from a total of 5 266 380 pregnancies (incidence of 6.5 per 100 000 pregnancies). Inpatient maternal mortality rate was 7%, and infant mortality rate was 3.5% among patients with PAMI. There was a nonsignificant trend toward an increase in PAMI incidence from 2003 to 2011, possibly attributable to higher incidence of spontaneous coronary artery dissection, vasospasm, and Takotsubo syndrome. PAMI, when compared with pregnant patients without myocardial infarction, was significant for older age (aged >30 years in 72% versus 37%, P<0.0005), higher preponderance of Black race (12% versus 6%, P<0.00005), lower socioeconomic status (median household income in lowest quartile 26% versus 20%, P=0.04), higher prevalence of hypertension (26% versus 7%, P<0.0005), diabetes (7% versus 1%, P<0.0005), anemia (31% versus 7%, P<0.0001), amphetamine use (1% versus 0%, P<0.00005), cocaine use (2% versus 0.2%, P<0.0001), and smoking (6% versus 1%, P=0.0001). Conclusions There has been a trend toward an increase in PAMI incidence in California over the past decade, with an increasing trend in spontaneous coronary artery dissection, vasospasm, and Takotsubo syndrome as mechanisms. These findings warrant further investigation.

Circulating Levels of MicroRNAs Associated With Hypertension: A Cross-Sectional Study in Male and Female South African Participants

MicroRNAs are non-coding, post-transcriptional regulators of gene expression and their dysregulation has been associated with development of various diseases, including hypertension. Consequently, understanding their role in the pathogenesis and progression of disease is essential. Prior research focusing on microRNAs in disease has provided a basis for understanding disease prognosis and offered possible channels for therapeutic interventions. Herein, we aimed to investigate possible differences in the expression profiles of five microRNAs in the blood of participants grouped on the basis of their hypertension status. This was done to elucidate the possible roles played by these microRNAs in the development of hypertension. Using quantitative reverse transcription polymerase chain reaction, we evaluated the expression levels of miR-126-3p, 30a-5p, 182-5p, 30e-3p, and 1299 in the whole blood of 1456 participants, normotensive (n = 573), screen-detected hypertensive (n = 304) and known hypertensive (n = 579). The expression of miR-126-3p and 182-5p was significantly higher in known hypertensives relative to both screen-detected hypertensives and normotensives, and also in screen-detected hypertensives vs normotensives. A significant association between the expression of miR-126-3p, 182-5p, and 30a-5p and known hypertension was also evident. This study demonstrated dysregulated miR-126-3p, 182-5p, and 30a-5p expression in hypertension, highlighting the possible efficacy of these microRNAs as targets for the diagnosis of hypertension as well as the development of microRNA-based therapies.

Matrix stiffness modulates tip cell formation through the p-PXN-Rac1-YAP signaling axis

Endothelial tip cell outgrowth of blood-vessel sprouts marks the initiation of angiogenesis which is critical in physiological and pathophysiological procedures. However, how mechanical characteristics of extracellular matrix (ECM) modulates tip cell formation has been largely neglected. In this study, we found enhanced CD31 expression in the stiffening outer layer of hepatocellular carcinoma than in surrounding soft tissues. Stiffened matrix promoted sprouting from endothelial cell (EC) spheroids and upregulated expressions of tip cell-enriched genes in vitro. Moreover, tip cells showed increased cellular stiffness, more actin cytoskeleton organization and enhanced YAP nuclear transfer than stalk and phalanx ECs. We further uncovered that substrate stiffness regulates FAK and Paxillin phosphorylation in focal adhesion of ECs promoting Rac1 transition from inactive to active state. YAP is subsequently activated and translocated into nucleus, leading to increased tip cell specification. p-Paxillin can also loosen the intercellular connection which also facilitates tip cell specification. Collectively our present study shows that matrix stiffness modulates tip cell formation through p-PXN-Rac1-YAP signaling axis, shedding light on the role of mechanotransduction in tip cell formation. This is of special significance in biomaterial design and treatment of some pathological situations.

•

Mechanotransduction is implicated in angiogenesis and tip cell formation.

•

Tip cells showed different mechanical properties from stalk and phalanx ECs.

•

Paxillin, Rac1 and YAP might be novel treatment targets for some diseases.

•

Material stiffness affects tip cell specification.

Adding a "Notch" to Cardiovascular Disease Therapeutics: A MicroRNA-Based Approach

Dysregulation of the Notch pathway is implicated in the pathophysiology of cardiovascular diseases (CVDs), but, as of today, therapies based on the re-establishing the physiological levels of Notch in the heart and vessels are not available. A possible reason is the context-dependent role of Notch in the cardiovascular system, which would require a finely tuned, cell-specific approach. MicroRNAs (miRNAs) are short functional endogenous, non-coding RNA sequences able to regulate gene expression at post-transcriptional levels influencing most, if not all, biological processes. Dysregulation of miRNAs expression is implicated in the molecular mechanisms underlying many CVDs. Notch is regulated and regulates a large number of miRNAs expressed in the cardiovascular system and, thus, targeting these miRNAs could represent an avenue to be explored to target Notch for CVDs. In this Review, we provide an overview of both established and potential, based on evidence in other pathologies, crosstalks between miRNAs and Notch in cellular processes underlying atherosclerosis, myocardial ischemia, heart failure, calcification of aortic valve, and arrhythmias. We also discuss the potential advantages, as well as the challenges, of using miRNAs for a Notch-based approach for the diagnosis and treatment of the most common CVDs.

MicroRNAs as Important Regulators Mediate the Multiple Differentiation of Mesenchymal Stromal Cells

MicroRNAs (miRNAs) are endogenous short non-encoding RNAs which play a critical role on the output of the proteins, and influence multiple biological characteristics of the cells and physiological processes in the body. Mesenchymal stem/stromal cells (MSCs) are adult multipotent stem cells and characterized by self-renewal and multidifferentiation and have been widely used for disease treatment and regenerative medicine. Meanwhile, MSCs play a critical role in maintaining homeostasis in the body, and dysfunction of MSC differentiation leads to many diseases. The differentiation of MSCs is a complex physiological process and is the result of programmed expression of a series of genes. It has been extensively proven that the differentiation process or programmed gene expression is also regulated accurately by miRNAs. The differentiation of MSCs regulated by miRNAs is also a complex, interdependent, and dynamic process, and a full understanding of the role of miRNAs will provide clues on the appropriate upregulation or downregulation of corresponding miRNAs to mediate the differentiation efficiency. This review summarizes the roles and associated signaling pathways of miRNAs in adipogenesis, chondrogenesis, and osteogenesis of MSCs, which may provide new hints on MSCs or miRNAs as therapeutic strategies for regenerative medicine and biotherapy for related diseases.

The Vital Roles of Mesenchymal Stem Cells and the Derived Extracellular Vesicles in Promoting Angiogenesis After Acute Myocardial Infarction

Acute myocardial infarction (AMI) is an event of ischemic myocardial necrosis caused by acute coronary artery occlusion, which ultimately leads to a large loss of cardiomyocytes. The prerequisite of salvaging ischemic myocardium and improving cardiac function of patients is to provide adequate blood perfusion in the infarcted area. Apart from reperfusion therapy, it is also urgent and imperative to promote angiogenesis. Recently, growing evidence based on promising preclinical data indicates that mesenchymal stem cells (MSCs) can provide therapeutic effects on AMI by promoting angiogenesis. Extracellular vesicles (EVs), membrane-encapsulated vesicles with complex cargoes, including proteins, nucleic acids, and lipids, can be derived from MSCs and represent part of their functions, so EVs also possess the ability to promote angiogenesis. However, poor control of the survival and localization of MSCs hindered clinical transformation and made scientists start looking for new approaches based on MSCs. Identifying the role of MSCs and their derived EVs in promoting angiogenesis can provide a theoretical basis for improved MSC-based methods, and ultimately promote the clinical treatment of AMI. This review highlights potential proangiogenic mechanisms of transplanted MSCs and the derived EVs after AMI and summarizes the latest literature concerning the novel methods based on MSCs to maximize the angiogenesis capability.

MicroRNA-30a regulates acute cerebral ischemia-induced blood-brain barrier damage through ZnT4/zinc pathway

The mechanism of early blood-brain barrier (BBB) disruption after stroke has been intensively studied but still not fully understood. Here, we report that microRNA-30a (miR-30a) could mediate BBB damage using both cellular and animal models of ischemic stroke. In the experiments in vitro, inhibition of miR-30a decreased BBB permeability, prevented the degradation of tight junction proteins, and reduced intracellular free zinc in endothelial cells. We found that the zinc transporter ZnT4 was a direct target of negative regulation by miR-30a, and ZnT4/zinc signaling pathway contributed significantly to miR-30a-mediated BBB damage. Consistent with these in vitro findings, treatment with miR-30a inhibitor reduced zinc accumulation, increased the expression of ZnT4, and prevented the loss of tight junction proteins in microvessels of ischemic animals. Furthermore, inhibition of miR-30a, even at 90 min post onset of middle cerebral artery occlusion, prevented BBB damage, reduced infarct volume, and ameliorated neurological deficits. Together, our findings provide novel insights into the mechanisms of cerebral ischemia-induced BBB disruption and indicate miR-30a as a regulator of BBB function that can be an effective therapeutic target for ischemic stroke.

Transcriptome analysis of arterial and venous circulating miRNAs during hypertension

Most current circulating miRNA biomarkers are derived from peripheral venous blood, whereas miRNA deregulation in arterial blood in disease conditions has been largely ignored. To explore whether peripheral venous blood miRNAs could represent a bona fide specific miRNA deregulation pattern, we selected hypertension, a disease that is particularly associated with vessels, as the model. Circulating miRNA profiles of arterial and venous blood from spontaneously hypertensive (SHR) rats and their corresponding controls (i.e., WKY rats) were investigated by next-generation miRNA sequencing. Little miRNAs were observed between arterial and venous circulating miRNAs in WKY rats. Interestingly, this number was enhanced in SHR hypertensive rats. Bioinformatical analysis of disease association, enriched target genes and the regulatory transcription factors of these differentially expressed miRNAs implied a potential functional link with cardiovascular disease-related functions. Comparisons between arterial and venous miRNAs in hypertension-versus-control conditions also revealed prominent disease association of circulating miRNAs and their target genes in arteries but not in veins. Moreover, a young non-hypertensive animal model in SHR background (i.e. JSHR) was used as a second control for SHR. Additional transcriptomic analysis and droplet digital PCR validation of arterial and venous deregulated miRNAs among SHR and its two controls (WKY, JSHR) revealed a noticeable consensus of artery-deregulated miRNAs in hypertension and two novel arterial circulating signatures (miR-455-3p and miR-140-3p) of hypertension. These results suggest the necessity of re-evaluating the efficacy of certain venous miRNAs identified in previous studies as potential biomarkers in cardiovascular diseases or a wider disease spectrum.

Involvement of miR-30a-5p and miR-30d in Endothelial to Mesenchymal Transition and Early Osteogenic Commitment under Inflammatory Stress in HUVEC

The endothelial to mesenchymal transition (End–MT) can be associated with vascular calcification, by providing mesengenic progenitors. In this study, we investigated a link between End–MT and the osteogenic process and explored the involvement of miR-30a-5p and miR-30d as potential regulators of these processes. End–MT was induced in Human Umbilical Vein Endothelial Cells (HUVEC) through transforming growth factor-β1 (TGF-β1), TGFβ-3 and tumor necrosis factor-α (TNF-α), for 24 h and 6 days. End–MT mediators, mesenchymal and osteo/chondrogenic markers were analyzed through Real-Time PCR, immunofluorescence, flow cytometry and Western Blot. miR-30a-5p and miR-30d over-expression was carried out in HUVEC to explore their effects on End–MT and osteogenic differentiation. HUVEC at 24 h and 6 days gained mesenchymal morphology markers, including matrix metalloproteinase 9 (MMP-9), SLUG, VIMENTIN and α-smooth muscle actin (α-SMA), and a significant migratory potential, notably with TNF-α. After 6 days, the osteo/chondrogenic markers runt-related transcription factor 2 (RUNX-2) and SRY box transcription factor 9 (SOX-9) were upregulated. At this time point, miR-30a-5p and miR-30d decreased. Over-expression of miR-30a-5p and miR-30d affected End–MT mediators and the osteogenic potency in HUVEC, by reducing SLUG, VIMENTIN and RUNX-2. Our data suggest that End–MT represents a key link between inflammation and vascular calcification. Further, miR-30a-5p and miR-30d can regulate both the End–MT and the osteogenic processes, prompting future studies for exploring their potential use as therapeutic targets or biomarkers in vascular diseases.

Chronic Kidney Disease-Associated Inflammation Increases the Risks of Acute Kidney Injury and Mortality after Cardiac Surgery

Cardiovascular mortality increases with decreasing renal function although the cause is yet unknown. Here, we have investigated whether low chronic inflammation in chronic kidney diseases (CKD) could contribute to increased risk for coronary artery diseases (CAD). Thus, a prospective case–control study was conducted in patients with CAD and CKD undergoing coronary artery bypass graft surgery with the aim of detecting differences in cardiovascular outcomes, epicardial adipose tissue volume, and inflammatory marker activity associated with renal dysfunction. Expression of membrane CD14 and CD16, inflammatory cytokines and chemokines, mitogen-activated protein (MAP) kinases and hsa-miR-30a-5p were analyzed in peripheral blood mononuclear cells (PBMCs). Epicardial fat volume and tissue inflammation in perivascular adipose tissue and in the aorta were also studied. In the present study, 151 patients were included, 110 with CAD (51 with CKD) and 41 nonCAD controls (15 with CKD). CKD increased the risk of cardiac surgery–associated acute kidney injury (CSA-AKI) as well as the 30-day mortality after cardiac surgery. Higher counts of CD14⁺⁺CD16⁺ monocytes were associated with vascular inflammation, with an increased expression of IL1β, and with CKD in CAD patients. Expression of hsa-miR-30a-5p was correlated with hypertension. We conclude that CKD patients show an increased risk of CSA-AKI and mortality after cardiovascular surgery, associated with the expansion of the CD14⁺⁺CD16⁺ subset of proinflammatory monocytes and with IL1β expression. We propose that inflammation associated with CKD may contribute to atherosclerosis (ATH) pathogenesis.

Extracellular Vesicle miRNAs in the Promotion of Cardiac Neovascularisation

Cardiovascular disease (CVD) is the leading cause of mortality worldwide claiming almost 17. 9 million deaths annually. A primary cause is atherosclerosis within the coronary arteries, which restricts blood flow to the heart muscle resulting in myocardial infarction (MI) and cardiac cell death. Despite substantial progress in the management of coronary heart disease (CHD), there is still a significant number of patients developing chronic heart failure post-MI. Recent research has been focused on promoting neovascularisation post-MI with the ultimate goal being to reduce the extent of injury and improve function in the failing myocardium. Cardiac cell transplantation studies in pre-clinical models have shown improvement in cardiac function; nonetheless, poor retention of the cells has indicated a paracrine mechanism for the observed improvement. Cell communication in a paracrine manner is controlled by various mechanisms, including extracellular vesicles (EVs). EVs have emerged as novel regulators of intercellular communication, by transferring molecules able to influence molecular pathways in the recipient cell. Several studies have demonstrated the ability of EVs to stimulate angiogenesis by transferring microRNA (miRNA, miR) molecules to endothelial cells (ECs). In this review, we describe the process of neovascularisation and current developments in modulating neovascularisation in the heart using miRNAs and EV-bound miRNAs. Furthermore, we critically evaluate methods used in cell culture, EV isolation and administration.

Folic acid supplement rescues ethanol-induced developmental defects in the zebrafish embryos

Fetal alcohol syndrome (FASD) describes a range of birth defects. Mechanisms of FASD-associated defects are not well understood. It has great significance to investigate whether nutrient supplements like folic acid (FA) can effectively rescue ethanol-induced defects. Moreover, it is very important to determine the optimal time for FA supplementation when it can most effectively antagonize the teratogenic effects of ethanol during embryonic development. Our results indicated that ethanol exposure interrupted the development of zebrafish embryos and induced multiple defects in cardiac function, pharyngeal arch arteries, vessel, craniofacial cartilage, pharyngeal arches, brain, somite and hemoglobin formation. The expressions of critical genes that play important roles in above organs such as tbx1, flk-1, hand2, ngn1, huc, titin, gata-1 and c-myb were reduced, and the apoptosis was increased in ethanol-treated group. FA supplementation could reverse ethanol-induced defects, improve the decreased expressions of above genes and reduce the apoptosis. We also found that giving FA at 6-12 h post-fertilization (hpf), which is at the gastrula period (5.25-10 hpf), can obviously prevent the teratogenicity of ethanol. This research provides clues for elucidating the mechanism of fetal abnormalities caused by alcohol intake and for preventing FASD.

Circulating miR-30a-5p and miR-182-5p in Prediabetes and Screen-Detected Diabetes Mellitus

BACKGROUND

microRNAs (miRNAs) have been touted as potential diagnostic and prognostic biomarkers for various diseases. The aim of the present study was to evaluate the diagnostic value of miR-30a-5p and miR-182-5p for prediabetes and screen-detected type 2 diabetes mellitus (T2DM).

METHODS

The study included 1270 participants (207 prediabetes, 94 screen-detected diabetes and 969 normotolerant) from the Vascular and Metabolic Health (VMH) study. Whole blood levels of miR-30a-5p and miR-182-5p were quantitated by RT-qPCR. Multivariable logistic regressions were used to relate miRNAs with prediabetes or T2DM and receiver operating characteristic (ROC) curves were used to evaluate the ability of each miRNA to diagnose these conditions.

RESULTS

Both miRNAs were significantly highly expressed in individuals with prediabetes or T2DM (both ≥3.2-fold, and p<0.001). We also observed significant under-expression in T2DM relative to prediabetes for miR-182-5p (0.49-fold, p=0.001). Age, sex and BMI-adjusted partial correlation coefficient analysis revealed a significant correlation between the two miRNAs across glucose tolerance statuses (r≥0.932, p<0.001). In normotolerant individuals, both miRNAs showed a negative correlation with waist circumference and positive correlation with HDL-cholesterol whilst in T2DM they correlated positively with hip circumference, 2-hour insulin, HDL- and LDL-cholesterol. Multivariable logistic regressions revealed both miRNAs to be consistently and continuously associated with prediabetes or T2DM (OR≥1.18, 95% 95% CI: 1.10-1.28, p<0.001), while only miR-182-5p associated with a reduced prevalence of T2DM relative to prediabetes (OR: 0.89, 95% CI: 0.83-0.96, p=0.003). In ROC analyses, miR-182-5p almost outperformed HbA1c in diagnosing prediabetes; area under the curve 0.74 vs 0.69.

CONCLUSION

Our findings demonstrate that miR-30a-5p and miR-182-5p are associated with dysglycaemia and could potentially predict prediabetes, particularly miR-182-5p.

MicroRNA expression profile in retina and choroid in oxygen-induced retinopathy model

Background

Ischemic retinopathies (IRs) are leading causes of visual impairment. They are characterized by an initial phase of microvascular degeneration and a second phase of aberrant pre-retinal neovascularization (NV). microRNAs (miRNAs) regulate gene expression, and a number play a role in normal and pathological NV. But, post-transcriptional modulation of miRNAs in the eye during the development of IRs has not been systematically evaluated.

Aims & methods

Using Next Generation Sequencing (NGS) we profiled miRNA expression in the retina and choroid during vasodegenerative and NV phases of oxygen-induced retinopathy (OIR).

Results

Approximately 20% of total miRNAs exhibited altered expression (up- or down-regulation); 6% of miRNA were found highly expressed in retina and choroid of rats subjected to OIR. During OIR-induced vessel degeneration phase, miR-199a-3p, -199a-5p, -1b, -126a-3p displayed a robust decreased expression (> 85%) in the retina. While in the choroid, miR-152-3p, -142-3p, -148a-3p, -532-3p were upregulated (>200%) and miR-96-5p, -124-3p, -9a-3p, -190b-5p, -181a-1-3p, -9a-5p, -183-5p were downregulated (>70%) compared to controls. During peak pathological NV, miR-30a-5p, -30e-5p and 190b-5p were markedly reduced (>70%), and miR-30e-3p, miR-335, -30b-5p strongly augmented (by up to 300%) in the retina. Whereas in choroid, miR-let-7f-5p, miR-126a-5p and miR-101a-3p were downregulated by (>81%), and miR-125a-5p, let-7e-5p and let-7g-5p were upregulated by (>570%) during NV. Changes in miRNA observed using NGS were validated using qRT-PCR for the 24 most modulated miRNAs. In silico approach to predict miRNA target genes (using algorithms of miRSystem database) identified potential new target genes with pro-inflammatory, apoptotic and angiogenic properties.

Conclusion

The present study is the first comprehensive description of retinal/choroidal miRNAs profiling in OIR (using NGS technology). Our results provide a valuable framework for the characterization and possible therapeutic potential of specific miRNAs involved in ocular IR-triggered inflammation, angiogenesis and degeneration.

Comparative analysis of milk microRNA in the therian lineage highlights the evolution of lactation

Milk is a complex secretion that has an important role in mammalian reproduction. It is only recently that sequencing technologies have allowed the identification and quantification of microRNA (miRNA) in milk of a growing number of mammalian species. This provides a novel window on the study of the evolution and functionality of milk through the comparative analysis of milk miRNA content. Here, milk miRNA sequencing data from five species (one marsupial (tammar wallaby) and four eutherians (human, mouse, cow and pig)) have been retrieved from public depositories and integrated in order to perform a comparison of milk miRNA profiles. The study shows that milk miRNA composition varies widely between species, except for a few miRNAs that are ubiquitously expressed in the milk of all mammals and indicates that milk miRNA secretion has broadly evolved during mammalian evolution. The putative functions of the most abundant milk miRNAs are also discussed.

Endothelial miR-30c suppresses tumor growth via inhibition of TGF-β-induced Serpine1

In tumors, extravascular fibrin forms provisional scaffolds for endothelial cell (EC) growth and motility during angiogenesis. We report that fibrin-mediated angiogenesis was inhibited and tumor growth delayed following postnatal deletion of Tgfbr2 in the endothelium of Cdh5-CreERT2 Tgfbr2fl/fl mice (Tgfbr2iECKO mice). ECs from Tgfbr2iECKO mice failed to upregulate the fibrinolysis inhibitor plasminogen activator inhibitor 1 (Serpine1, also known as PAI-1), due in part to uncoupled TGF-β-mediated suppression of miR-30c. Bypassing TGF-β signaling with vascular tropic nanoparticles that deliver miR-30c antagomiRs promoted PAI-1-dependent tumor growth and increased fibrin abundance, whereas miR-30c mimics inhibited tumor growth and promoted vascular-directed fibrinolysis in vivo. Using single-cell RNA-Seq and a NanoString miRNA array, we also found that subtypes of ECs in tumors showed spectrums of Serpine1 and miR-30c expression levels, suggesting functional diversity in ECs at the level of individual cells; indeed, fresh EC isolates from lung and mammary tumor models had differential abilities to degrade fibrin and launch new vessel sprouts, a finding that was linked to their inverse expression patterns of miR-30c and Serpine1 (i.e., miR-30chi Serpine1lo ECs were poorly angiogenic and miR-30clo Serpine1hi ECs were highly angiogenic). Thus, by balancing Serpine1 expression in ECs downstream of TGF-β, miR-30c functions as a tumor suppressor in the tumor microenvironment through its ability to promote fibrin degradation and inhibit blood vessel formation.

A ribosomal DNA-hosted microRNA regulates zebrafish embryonic angiogenesis

MicroRNAs (miRNAs) are single-stranded small non-coding RNAs, generally 18-25 nucleotides in length, that act as repressors of gene expression. miRNAs are encoded by independent genes or processed from a variety of different RNA species. So far, there is no evidence showing that the ribosomal DNA-hosted microRNA is implicated in vertebrate development. Currently, we found a highly expressed small RNA hosted in ribosomal DNA was predicted as a novel miRNA, named miR-ntu1, in zebrafish endothelial cells by deep sequencing analysis. The miRNA was validated by custom-designed Taqman PCR, Northern Blot, and in silico analysis. Furthermore, we demonstrated that miR-ntu1 played a crucial role in zebrafish angiogenesis via modulation of Notch signaling. Our findings provide a notable case that a miRNA hosted in ribosomal DNA is involved in vertebrate development.

MicroRNA-30a as a candidate underlying sex-specific differences in neonatal hyperoxic lung injury: implications for BPD

Premature male neonates are at a greater risk of developing bronchopulmonary dysplasia (BPD). The reasons underlying sexually dimorphic outcomes in premature neonates are not known. The role of miRNAs in mediating sex biases in BPD is understudied. Analysis of the pulmonary transcriptome revealed that a large percentage of angiogenesis-related differentially expressed genes are miR-30a targets. We tested the hypothesis that there is differential expression of miR-30a in vivo and in vitro in neonatal human pulmonary microvascular endothelial cells (HPMECs) upon exposure to hyperoxia. Neonatal male and female mice (C57BL/6) were exposed to hyperoxia [95% fraction of inspired oxygen (FiO2), postnatal day ( PND) 1-5] and euthanized on PND 7 and 21. HPMECs (18-24-wk gestation donors) were subjected to hyperoxia (95% O2 and 5% CO2) or normoxia (air and 5% CO2) up to 72 h. miR-30a expression was increased in both males and females in the acute phase ( PND 7) after hyperoxia exposure. However, at PND 21 (recovery phase), female mice showed significantly higher miR-30a expression in the lungs compared with male mice. Female HPMECs showed greater expression of miR-30a in vitro upon exposure to hyperoxia. Delta-like ligand 4 (Dll4) was an miR-30a target in HPMECs and showed sex-specific differential expression. miR-30a increased angiogenic sprouting in vitro in female HPMECs. Lastly, we show decreased expression of miR-30a and increased expression of DLL4 in human BPD lung samples compared with controls. These results support the hypothesis that miR-30a could, in part, contribute to the sex-specific molecular mechanisms in play that lead to the sexual dimorphism in BPD.

MicroRNAs as Potential Biomarkers in Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare and aggressive type of skin cancer associated with a poor prognosis. This carcinoma was named after its presumed cell of origin, the Merkel cell, which is a mechanoreceptor cell located in the basal epidermal layer of the skin. Merkel cell polyomavirus seems to be the major causal factor for MCC because approximately 80% of all MCCs are positive for viral DNAs. UV exposure is the predominant etiological factor for virus-negative MCCs. Intracellular microRNA analysis between virus-positive and virus-negative MCC cell lines and tumor samples have identified differentially expressed microRNAs. Comparative microRNA profiling has also been performed between MCCs and other non-MCC tumors, but not between normal Merkel cells and malignant Merkel cells. Finally, Merkel cell polyomavirus encodes one microRNA, but its expression in virus-positive MCCs is low, or non-detectable or absent, jeopardizing its biological relevance in tumorigenesis. Here, we review the results of microRNA studies in MCCs and discuss the potential application of microRNAs as biomarkers for the diagnosis, progression and prognosis, and treatment of MCC.

* Glioblastoma Exosomes for Therapeutic Angiogenesis in Peripheral Ischemia

Peripheral ischemia as a result of occlusive vascular disease is a widespread problem in patients older than the age of 65. Angiogenic therapies that can induce microvascular growth have great potential for providing a long-lasting solution for patients with ischemia and would provide an appealing alternative to surgical and percutaneous interventions. However, many angiogenic therapies have seen poor efficacy in clinical trials, suggesting that patients with long-term peripheral ischemia have considerable therapeutic resistance to angiogenic stimuli. Glioblastoma is one of the most angiogenic tumor types, inducing robust vessel growth in the area surrounding the tumor. One major angiogenic mechanism used by the tumor cells to induce blood vessel growth is the production of exosomes and other extracellular vesicles that can carry pro-angiogenic and immunomodulatory signals. Here, we explored whether the pro-angiogenic aspects of glioblastoma-derived exosomes could be harnessed to promote angiogenesis and healing in the context of peripheral ischemic disease. We demonstrate that the exosomes derived from glioblastoma markedly enhance endothelial cell proliferation and increase endothelial tubule formation in vitro. An analysis of the microRNA expression using next generation sequencing identified that exosomes contained a high concentration of miR-221. In addition, we found that glioblastoma exosomes contained significant amounts of the proteoglycans glypican-1 and syndecan-4, which can serve as co-receptors for angiogenic factors, including fibroblast growth factor-2 (FGF-2). In a hindlimb ischemia model in mice, we found that the exosomes promoted enhanced revascularization in comparison to control alginate gels and FGF-2 treatment alone. Taken together, our results support the fact that glioblastoma-derived exosomes have powerful effects in increasing revascularization in the context of peripheral ischemia.

miR-30 Family: A Promising Regulator in Development and Disease

MicroRNAs (miRNAs) are small noncoding RNAs that negatively regulate posttranscriptional expression of target genes. Accumulating evidences have demonstrated that the miR-30 family, as a member of microRNAs, played a crucial regulating role in the development of tissues and organs and the pathogenesis of clinical diseases, which indicated that it may be a promising regulator in development and disease. This review aims to clarify the current progress on the regulating role of miR-30 family in tissues and organs development and related disease and highlight their research prospective in the future.

Mesenchymal stem cells release exosomes that transfer miRNAs to endothelial cells and promote angiogenesis

Mesenchymal stem cells (MSCs) have been found to benefit patients with a variety of ischemic diseases via promoting angiogenesis. It is also well established that exosomes secreted from MSCs deliver bioactive molecules, including microRNAs (miRs) to recipient cells. Therefore, we hypothesized that exosomes secreted from MSCs deliver miRs into endothelial cells and mediate angiogenesis. The pro-angiogenic stimulatory capacity of exosomes was investigated using tube-like structure formation and spheroid-based sprouting of human umbilical vein endothelial cells (HUVECs), and in vivo Matrigel plug assay. The secretion of pro-angiogenic miRs (pro-angiomiRs) from MSCs into culture medium and transfer of the miRs to HUVECs were confirmed using real-time quantitative PCR. Supplementation of the exosome secretion blocker GW4869 (10 μM) reduced the pro-angiomiRs in the MSC-derived conditioned medium (CdM^MSC). Addition of exosomes isolated from CdM^MSC could directly 1) promote HUVEC tube-like structure formation in vitro; 2) mobilize endothelial cells into Matrigel plug subcutaneously transplanted into mice; and 3) increase blood flow inside Matrigel plug. Fluorescence tracking showed that the exosomes were internalized rapidly by HUVECs causing an upregulated expression of pro-angiomiRs in HUVECs. Loss-and-gain function of the pro-angiomiRs (e.g., miR-30b) in MSCs significantly altered the pro-angiogenic properties of these MSC-derived exosomes, which could be associated with the regulation of their targets in HUVECs. These results suggest that exosomal transfer of pro-angiogenic miRs plays an important role in MSC mediated angiogenesis and stem cell-to-endothelial cell communication.

Temporal and spatial expression of fgfbp genes in zebrafish

Fibroblast growth factor binding proteins (FGFBPs) are a class of secreted proteoglycans that function as an extracellular chaperone for locally stored FGFs and enhance FGF signaling. To date, all three human FGFBP genes have been identified and one orthologue fgfbp1a has been studied in zebrafish embryos. Here, we described the cloning and expression patterns of four novel FGFBP orthologues in zebrafish, fgfbp1b, fgfbp2a, fgfbp2b, and fgfbp3. Quantitative PCR and whole-mount in situ hybridization results showed that all transcripts except fgfbp2a are initially expressed in a maternal manner. fgfbp1b, fgfbp2b and fgfbp2a transcripts are expressed broadly in the head at 24 h post-fertilization (hpf), and then become restricted to the pharyngeal tissue, pectoral fins, and liver, respectively. fgfbp3 is abundantly expressed in the central nervous system (CNS) throughout embryonic and larval development. In adults, fgfbp family manifests the tissue specific patterns of expression with fgfbp3 robustly expressed in muscle and heart. Our work offers a starting point to uncover roles of FGFBP family genes and the possible mechanisms of FGF-dependent and -independent actions of FGFBP in vertebrates.

Role of MicroRNA in Endothelial Dysfunction and Hypertension

Purpose of Review

Hypertension is either a cause or a consequence of the endothelial dysfunction and a major risk factor for cardiovascular disease (CVD). In vitro and in vivo studies established that microRNAs (miRNAs) are decisive for endothelial cell gene expression and function in various pathological conditions associated with CVD.

This review provides an overview of the miRNA role in controlling the key connections between endothelial dysfunction and hypertension.

Recent Findings

Herein we summarize the present understanding of mechanisms underlying hypertension and its associated endothelial dysfunction as well as the miRNA role in endothelial cells with accent on the modulation of renin-angiotensin-aldosterone-system, nitric oxide, oxidative stress and on the control of vascular inflammation and angiogenesis in relation to endothelial dysfunction in hypertension. In particular, latest insights in the identification of endothelial-specific microRNAs and their targets are added to the understanding of miRNA significance in hypertension.

Summary

This comprehensive knowledge of the role of miRNAs in endothelial dysfunction and hypertension and of molecular mechanisms proposed for miRNA actions may offer novel diagnostic biomarkers and therapeutic targets for controlling hypertension-associated endothelial dysfunction and other cardiovascular complications.

The somite-secreted factor Maeg promotes zebrafish embryonic angiogenesis

MAM and EGF containing gene (MAEG), also called Epidermal Growth Factor-like domain multiple 6 (EGFL6), belongs to the epidermal growth factor repeat superfamily. The role of Maeg in zebrafish angiogenesis remains unclear. It was demonstrated that maeg was dynamically expressed in zebrafish developing somite during a time window encompassing many key steps in embryonic angiogenesis. Maeg loss-of-function embryos showed reduced endothelial cell number and filopodia extensions of intersegmental vessels (ISVs). Maeg gain-of-function induced ectopic sprouting evolving into a hyperbranched and functional perfused vasculature. Mechanistically we demonstrate that Maeg promotes angiogenesis dependent on RGD domain and stimulates activation of Akt and Erk signaling in vivo. Loss of Maeg or Itgb1, augmented expression of Notch receptors, and inhibiting Notch signaling or Dll4 partially rescued angiogenic phenotypes suggesting that Notch acts downstream of Itgb1. We conclude that Maeg acts as a positive regulator of angiogenic cell behavior and formation of functional vessels.

The potential inhibitory effects of miR‑19b on vulnerable plaque formation via the suppression of STAT3 transcriptional activity

Atherosclerotic plaque growth requires angiogenesis, and acute coronary syndrome (ACS) is usually triggered by the rupture of unstable atherosclerotic plaques. Previous studies have identified typically circulating microRNA (miRNA/miR) profiles in patients with ACS. miRNAs serve important roles in the pathophysiology of atherosclerotic plaque progression. The present study aimed to investigate the potential role and mechanism of miR‑19b in plaque stability. miRNA array data indicated that 28 miRNAs were differentially expressed in the plasma of patients with unstable angina (UA; n=12) compared with in control individuals (n=12), and miR‑19b exhibited the most marked upregulation. Circulating miR‑19b levels were further validated in another independent cohort, which consisted of 34 patients with UA and 24 controls, by quantitative polymerase chain reaction. Gene Ontology annotations of the predicted target genes of miR‑19b suggested that miR‑19b may be involved in endothelial cell (EC) proliferation, migration and angiogenesis, which was confirmed by Cell Counting kit‑8, wound healing and tube formation assays in the present study. Finally, the present study indicated that miR‑19b may suppress signal transducer and activator of transcription 3 (STAT3) tyrosine phosphorylation and transcriptional activity in ECs, as determined by western blot analysis and luciferase reporter assay. In conclusion, the present study revealed that increased miR‑19b expression may delay unstable plaque progression in patients with UA by inhibiting EC proliferation, migration and angiogenesis via the suppression of STAT3 transcriptional activity.

MicroRNA-30b controls endothelial cell capillary morphogenesis through regulation of transforming growth factor beta 2

The importance of microRNA (miRNA) to vascular biology is becoming increasingly evident; however, the function of a significant number of miRNA remains to be determined. In particular, the effect of growth factor regulation of miRNAs on endothelial cell morphogenesis is incomplete. Thus, we aimed to identify miRNAs regulated by pro-angiogenic vascular endothelial growth factor (VEGF) and determine the effects of VEGF-regulated miRNAs and their targets on processes important for angiogenesis. Human umbilical vein endothelial cells (HUVECs) were thus stimulated with VEGF and miRNA levels assessed using microarrays. We found that VEGF altered expression of many miRNA, and for this study focused on one of the most significantly down-regulated miRNA in HUVECs following VEGF treatment, miR-30b. Using specific miRNA mimics, we found that overexpression of miR-30b inhibited capillary morphogenesis in vitro, while depletion of endogenous miR-30b resulted in increased capillary morphogenesis indicating the potential significance of down-regulation of miR-30b as a pro-angiogenic response to VEGF stimulation. MiR-30b overexpression in HUVEC regulated transforming growth factor beta 2 (TGFβ2) production, which led to increased phosphorylation of Smad2, indicating activation of an autocrine TGFβ signaling pathway. Up-regulation of TGFβ2 by miR-30b overexpression was found to be dependent on ATF2 activation, a transcription factor known to regulate TGFβ2 expression, as miR-30b overexpressing cells exhibited increased levels of phosphorylated ATF2 and depletion of ATF2 inhibited miR-30b-induced TGFβ2 expression. However, miR-30b effects on ATF2 were indirect and found to be via targeting of the known ATF2 repressor protein JDP2 whose mRNA levels were indirectly correlated with miR-30b levels. Increased secretion of TGFβ2 from HUVEC was shown to mediate the inhibitory effects of miR-30b on capillary morphogenesis as treatment with a neutralizing antibody to TGFβ2 restored capillary morphogenesis to normal levels in miR-30b overexpressing cells. These results support that the regulation of miR-30b by VEGF in HUVEC is important for capillary morphogenesis, as increased miR-30b expression inhibits capillary morphogenesis through enhanced expression of TGFβ2.

Notch Signaling in Development, Tissue Homeostasis, and Disease

Notch signaling is an evolutionarily highly conserved signaling mechanism, but in contrast to signaling pathways such as Wnt, Sonic Hedgehog, and BMP/TGF-β, Notch signaling occurs via cell-cell communication, where transmembrane ligands on one cell activate transmembrane receptors on a juxtaposed cell. Originally discovered through mutations in Drosophila more than 100 yr ago, and with the first Notch gene cloned more than 30 yr ago, we are still gaining new insights into the broad effects of Notch signaling in organisms across the metazoan spectrum and its requirement for normal development of most organs in the body. In this review, we provide an overview of the Notch signaling mechanism at the molecular level and discuss how the pathway, which is architecturally quite simple, is able to engage in the control of cell fates in a broad variety of cell types. We discuss the current understanding of how Notch signaling can become derailed, either by direct mutations or by aberrant regulation, and the expanding spectrum of diseases and cancers that is a consequence of Notch dysregulation. Finally, we explore the emerging field of Notch in the control of tissue homeostasis, with examples from skin, liver, lung, intestine, and the vasculature.

Tumor angiogenesis revisited: Regulators and clinical implications

Since Judah Folkman hypothesized in 1971 that angiogenesis is required for solid tumor growth, numerous studies have been conducted to unravel the angiogenesis process, analyze its role in primary tumor growth, metastasis and angiogenic diseases, and to develop inhibitors of proangiogenic factors. These studies have led in 2004 to the approval of the first antiangiogenic agent (bevacizumab, a humanized antibody targeting vascular endothelial growth factor) for the treatment of patients with metastatic colorectal cancer. This approval launched great expectations for the use of antiangiogenic therapy for malignant diseases. However, these expectations have not been met and, as knowledge of blood vessel formation accumulates, many of the original paradigms no longer hold. Therefore, the regulators and clinical implications of angiogenesis need to be revisited. In this review, we discuss recently identified angiogenesis mediators and pathways, new concepts that have emerged over the past 10 years, tumor resistance and toxicity associated with the use of currently available antiangiogenic treatment and potentially new targets and/or approaches for malignant and nonmalignant neovascular diseases.

Combretastatin A-4 efficiently inhibits angiogenesis and induces neuronal apoptosis in zebrafish

Cis-stilbene combretastatin A-4 (CA-4) and a large group of its derivant compounds have been shown significant anti-angiogenesis activity. However the side effects even the toxicities of these chemicals were not evaluated adequately. The zebrafish model has become an important vertebrate model for evaluating drug effects. The testing of CA-4 on zebrafish is so far lacking and assessment of CA-4 on this model will provide with new insights of understanding the function of CA-4 on angiogenesis, the toxicities and side effects of CA-4. We discovered that 7-9 ng/ml CA-4 treatments resulted in developmental retardation and morphological malformation, and led to potent angiogenic defects in zebrafish embryos. Next, we demonstrated that intraperitoneal injection of 5, 10 and 20 mg/kg CA-4 obviously inhibited vessel plexus formation in regenerated pectoral fins of adult zebrafish. Interestingly, we proved that CA-4 treatment induced significant cell apoptosis in central nervous system of zebrafish embryos and adults. Furthermore, it was demonstrated that the neuronal apoptosis induced by CA-4 treatment was alleviated in p53 mutants. In addition, notch1a was up-regulated in CA-4 treated embryos, and inhibition of Notch signaling by DAPT partially rescued the apoptosis in zebrafish central nervous system caused by CA-4.

Harnessing gene and drug delivery for vascularizing engineered tissue platforms

Enhancement of tissue vascularization is a therapeutic target for many ischemic conditions, and is crucial for successful engraftment of therapeutic cells for tissue regeneration. The authors present opportunities for using these platforms for dissecting the role of angiogenic mechanisms and highlight recent gene and drug delivery strategies for enhancing vascularization of engineered tissues. Modular tissue engineering is featured as an example.

MicroRNA-30a promotes chondrogenic differentiation of mesenchymal stem cells through inhibiting Delta-like 4 expression

AIMS

MicroRNAs (miRNAs) play important roles in chondrogenic differentiation of mesenchymal stem cells (MSCs). However, the regulation of miR-30a during such process has not yet been well understood. The aim of the study was to investigate the effects of miR-30a on chondrogenic differentiation of MSCs and explore the underlying mechanisms.

MATERIALS AND METHODS

MSCs were isolated from rat bone marrow, and their immunophenotypes and multilineage differentiation potentials were identified. MiR-30a mimics or inhibitor were transfected into rat MSCs and SW1353 cells, respectively, and then the effects of miR-30a on chondrogenic differentiation were detected. The predicted target gene Delta-like 4 (DLL4, a ligand of the Notch signaling family) was verified by luciferase reporter assay, quantitative real time PCR and western blot.

KEY FINDINGS

MiR-30a was significantly up-regulated during chondrogenic differentiation of rat MSCs. Additionally, transfection of miR-30a mimics remarkably promoted the differentiation of rat MSCs into chondrocytes as evidence by the notably increased mRNA and protein expression levels of chondrogenic markers Collagen II and aggrecan as well as the enhanced alcian blue staining intensity, whereas inhibition of miR-30a obviously suppressed such process. Furthermore, during chondrogenesis, DLL4 expression was found to significantly decrease at both mRNA and protein levels, which was negatively regulated by miR-30a through directly targeting the 3'UTR of DLL4.

SIGNIFICANCE

Our results indicate that miR-30a acts as a key promoter for chondrogenic differentiation of MSCs by down-regulating DLL4 expression, and provide a novel insight on miRNA-mediated MSC therapy for cartilage-related disorders including osteoarthritis.

MicroRNA-10a/10b represses a novel target gene mib1 to regulate angiogenesis

AIMS

MicroRNA-10 (miR-10) was originally shown to regulate angiogenesis by directly modulating the levels of membrane-bound fms-related tyrosine kinase 1 (mflt1) and its soluble splice isoform sflt1 post-transcriptionally in zebrafish. Given that flt1 knockdown incompletely rescues the angiogenic phenotypes in miR-10 morphants, flt1 is unlikely to be the only important target of miR-10 in endothelial cells (ECs). It will be interesting to investigate new mechanism responsible for angiogenic defect induced by miR-10 knockdown.

METHODS AND RESULTS

Firstly, we demonstrated that miR-10a and miR-10b (miR-10a/10b) were highly enriched in embryonic zebrafish ECs using deep sequencing, Taqman polymerase chain reaction, and in situ hybridisation. Subsequently, we proved that loss of miR-10a/10b impaired blood vessel outgrowth through regulating tip cell behaviours. Mib1 was identified as a potential direct target of miR-10a/10b through in silicon analysis and in vitro luciferase sensor assay. In vivo reporter assay in zebrafish embryos confirmed the binding of miR-10 with 3'-UTR of zebrafish mib1. Furthermore, inhibition of mib1 and Notch signaling rescued the angiogenic defects in miR-10-deficient zebrafish embryos. In addition, we provided evidences that miR-10 regulates human ECs behaviour through targeting Mib1 as well.

CONCLUSION

Taken together, these results indicate that miR-10 regulates the angiogenic behaviour in a Notch-dependent manner by directly targeting mib1.

MMGZ01, an anti-DLL4 monoclonal antibody, promotes nonfunctional vessels and inhibits breast tumor growth

Increasing evidence suggests that DLL4 (Delta-like 4)-Notch signaling plays a critical role in cell fate determination and differentiation in tissues. Blocking DLL4-Notch signaling results in inhibition of tumor growth, which is associated with increased nonfunctional vessels and poor perfusion in the tumor. We successfully generated a human DLL4 monoclonal antibody MMGZ01 that binds specifically to DLL4 to disrupt the interaction between DLL4 and Notch1. MMGZ01 showed high affinity to DLL4 to inhibit the DLL4-mediated human umbilical vein endothelial cell (HUVEC) phenotype. Furthermore, MMGZ01 stimulated HUVEC vessel sprouting and tubule formation in vitro. In addition, MMGZ01 had a pronounced effect in promoting immature vessels and reduced breast cancer cell growth in vivo. Finally, MMGZ01 treatment inhibited the proliferation of breast cancer cells, induced tumor cell apoptosis, suppressed mammosphere formation, decreased CD44(+)/CD24(-) cell population, and reduced epithelial mesenchymal transition (EMT). These findings suggest that antagonism of the DLL4-Notch signaling pathway might provide a potential therapeutic approach for breast cancer treatment.

MicroRNA-30 mediates anti-inflammatory effects of shear stress and KLF2 via repression of angiopoietin 2

MicroRNAs are endogenously expressed small noncoding RNAs that regulate gene expression. Laminar blood flow induces atheroprotective gene expression in endothelial cells (ECs) in part by upregulating the transcription factor KLF2. Here, we identified KLF2- and flow-responsive miRs that affect gene expression in ECs. Bioinformatic assessment of mRNA expression patterns identified the miR-30-5p seed sequence to be highly enriched in mRNAs that are downregulated by KLF2. Indeed, KLF2 overexpression and shear stress stimulation in vitro and in vivo increased the expression of miR-30-5p family members. Furthermore, we identified angiopoietin 2 (Ang2) as a target of miR-30. MiR-30 overexpression reduces Ang2 levels, whereas miR-30 inhibition by LNA-antimiRs induces Ang2 expression. Consistently, miR-30 reduced basal and TNF-α-induced expression of the inflammatory cell–cell adhesion molecules E-selectin, ICAM1 and VCAM1, which was rescued by stimulation with exogenous Ang2. In summary, KLF2 and shear stress increase the expression of the miR-30-5p family which acts in an anti-inflammatory manner in ECs by impairing the expression of Ang2 and inflammatory cell–cell adhesion molecules. The upregulation of miR-30-5p family members may contribute to the atheroprotective effects of shear stress.

Quantitative and qualitative analysis of small RNAs in human endothelial cells and exosomes provides insights into localized RNA processing, degradation and sorting

Exosomes are small vesicles that mediate cell-cell communication. They contain proteins, lipids and RNA, and evidence is accumulating that these molecules are specifically sorted for release via exosomes. We recently showed that endothelial-cell-produced exosomes promote angiogenesis in vivo in a small RNA-dependent manner. Recent deep sequencing studies in exosomes from lymphocytic origin revealed a broad spectrum of small RNAs. However, selective depletion or incorporation of small RNA species into endothelial exosomes has not been studied extensively. With next generation sequencing, we identified all known non-coding RNA classes, including microRNAs (miRNAs), small nucleolar RNAs, yRNAs, vault RNAs, 5p and 3p fragments of miRNAs and miRNA-like fragments. In addition, we mapped many fragments of messenger RNAs (mRNAs) and mitochondrial RNAs (mtRNAs). The distribution of small RNAs in exosomes revealed a considerable overlap with the distribution in the producing cells. However, we identified a remarkable enrichment of yRNA fragments and mRNA degradation products in exosomes consistent with yRNAs having a role in degradation of structured and misfolded RNAs in close proximity to endosomes. We propose that endothelial endosomes selectively sequester cytoplasmic RNA-degrading machineries taking part in gene regulation. The release of these regulatory RNAs via exosomes may have implications for endothelial cell-cell communication.

Non-coding RNAs and hypertension-unveiling unexpected mechanisms of hypertension by the dark matter of the genome

Hypertension is a major risk factor of cardiovascular diseases and a most important health problem in developed countries. Investigations on pathophysiology of hypertension have been based on gene products from coding region that occupies only about 1% of total genome region. On the other hand, non-coding region that occupies almost 99% of human genome has been regarded as "junk" for a long time and went unnoticed until these days. But recently, it turned out that noncoding region is extensively transcribed to non-coding RNAs and has various functions. This review highlights recent updates on the significance of non-coding RNAs such as micro RNAs and long non-coding RNAs (lncRNAs) on the pathogenesis of hypertension, also providing an introduction to basic biology of noncoding RNAs. For example, microRNAs are associated with hypertension via neuro-fumoral factor, sympathetic nerve activity, ion transporters in kidneys, endothelial function, vascular smooth muscle phenotype transformation, or communication between cells. Although reports of lncRNAs on pathogenesis of hypertension are scarce at the moment, new lncRNAs in relation to hypertension are being discovered at a rapid pace owing to novel techniques such as microarray or next-generation sequencing. In the clinical settings, clinical use of non-coding RNAs in identifying cardiovascular risks or developing novel tools for treating hypertension such as molecular decoy or mimicks is promising, although improvement in chemical modification or drug delivery system is necessary.

Epigenetics and arterial hypertension: the challenge of emerging evidence

Epigenetic phenomena include DNA methylation, post-translational histone modifications, and noncoding RNAs, as major marks. Although similar to genetic features of DNA for their heritability, epigenetic mechanisms differ for their potential reversibility by environmental and nutritional factors, which make them potentially crucial for their role in complex and multifactorial diseases. The function of these mechanisms is indeed gaining interest in relation to arterial hypertension (AH) with emerging evidence from cell culture and animal models as well as human studies showing that epigenetic modifications have major functions within pathways related to AH. Among epigenetic marks, the role of DNA methylation is mostly highlighted given the primary role of this epigenetic feature in mammalian cells. A lower global methylation was observed in DNA of peripheral blood mononuclear cells of hypertensive patients. Moreover, DNA hydroxymethylation appears modifiable by salt intake in a Dahl salt-sensitive rat model. The specific function of DNA methylation in regulating the expression of AH-related genes at promoter site was described for hydroxysteroid (11-beta) dehydrogenase 2 (HSD11B2), somatic angiotensin converting enzyme (sACE), Na+/K+/2Cl- cotransporter 1 (NKCC1), angiotensinogen (AGT), α-adducin (ADD1), and for other crucial genes in endocrine hypertension. Post-translational histone methylation at different histone 3 lysine residues was also observed to control the expression of genes related to AH as lysine-specific demethylase-1(LSD1), HSD11B2, and epithelial sodium channel subunit α (SCNN1A). Noncoding RNAs including several microRNAs influence genes involved in steroidogenesis and the renin-angiotensin-aldosterone pathway. In the present review, the current knowledge on the relationship between the main epigenetic marks and AH will be presented, considering the challenge of epigenetic patterns being modifiable by environmental factors that may lead toward novel implications in AH preventive and therapeutic strategies.

Notch signal integration in the vasculature during remodeling

Notch signaling plays many important roles in homeostasis and remodeling in the vessel wall, and serves a critical role in the communication between endothelial cells and smooth muscle cells. Within blood vessels, Notch signaling integrates with multiple pathways by mechanisms including direct protein–protein interaction, cooperative or synergistic regulation of signal cascades, and co-regulation of transcriptional targets. After establishment of the mature blood vessel, the spectrum and intensity of Notch signaling change during phases of active remodeling or disease progression. These changes can be mediated by regulation via microRNAs and protein stability or signaling, and corresponding changes in complementary signaling pathways. Notch also affects endothelial cells on a system level by regulating key metabolic components. This review will outline the most recent findings of Notch activity in blood vessels, with a focus on how Notch signals integrate with other molecular signaling pathways controlling vascular phenotype.

A microRNA-mediated regulatory loop modulates NOTCH and MYC oncogenic signals in B- and T-cell malignancies

Growing evidence suggests that microRNAs facilitate the cross-talk between transcriptional modules and signal transduction pathways. MYC and NOTCH1 contribute to the pathogenesis of lymphoid malignancies. NOTCH induces MYC, connecting two signaling programs that enhance oncogenicity. Here we show that this relationship is bidirectional and that MYC, via a microRNA intermediary, modulates NOTCH. MicroRNA-30a, a member of family of microRNAs that are transcriptionally suppressed by MYC, directly binds to and inhibits NOTCH1 and NOTCH2 expression. Using a murine model and genetically modified human cell lines, we confirmed that microRNA-30a influences NOTCH expression in a MYC-dependent fashion. In turn, through genetic modulation, we demonstrated that intracellular NOTCH1 and NOTCH2, by inducing MYC, suppressed microRNA-30a. Conversely, pharmacological inhibition of NOTCH decreased MYC expression, and ultimately de-repressedmicroRNA-30a. Examination of genetic models of gain and loss of microRNA-30a in diffuse large B-cell lymphoma (DLBCL) and T-acute lymphoblastic leukemia (T-ALL) cells suggested a tumor suppressive role for this microRNA. Finally, the activity of the microRNA-30a-NOTCH-MYC loop was validated in primary DLBCL and T-ALL samples. These data define the presence of a microRNA-mediated regulatory circuitry that may modulate the oncogenic signals originating from NOTCH and MYC.