Epidermal Growth Factor Like-domain 7 and miR-126 are abnormally expressed in diffuse Systemic Sclerosis fibroblasts

Systemic sclerosis (SSc) is characterized by microangiopathy with impaired reparative angiogenesis and fibrosis. Epidermal Growth Factor Like-domain 7 (EGFL7), firstly described in endothelial cells plays a pivotal role in angiogenesis. Fibroblasts (FBs) are involved in vascular remodeling, under physiological and pathological conditions. In this study, we investigated: (i) the expression of EGFL7 and its miR-126 in patients affected by diffuse cutaneous SSc (dcSSc); (ii) the ability of Transforming Growth Factor-beta (TGF-β) to modulate EGFL7 expression; (iii) the ability of EGFL7 to modulate COL1A1 expression and proliferation/migration, and (iv) the functional role of EGFL7 on angiogenesis. Patients were divided in 2 subsets: patients fulfilling the classification criteria in less than one year from Raynaud’s Phenomenon onset (Early Onset Subset–EOS), and all the others (Long Standing Subset–LSS). We show that EGFL7 expression is increased in EOS dcSSc skin and cultured FBs. EGFL7 is inducible by TGF-β on Healthy Controls (HC) FBs but not in SSc-FBs. EGFL7 decreases COL1A1 expression in EOS SSc-FBs while EGFL7 silencing up-regulates COL1A1 expression. EGFL7 promotes migration/invasion of EOS SSc-FBs but not proliferation. Finally, SSc-FBs, partially inhibit angiogenesis in organotypic coculture assays, and this is reversed by treatment with human recombinant (rh)EGFL7. We conclude that EGFL7 and its specific microRNA miR-126 may be involved in the pathogenesis of SSc vasculopathy and fibrosis.

miR-126 regulates glycogen trophoblast proliferation and DNA methylation in the murine placenta

A functional placenta develops through a delicate interplay of its vascular and trophoblast compartments. We have identified a previously unknown expression domain for the endothelial-specific microRNA miR-126 in trophoblasts of murine and human placentas. Here, we determine the role of miR-126 in placental development using a mouse model with a targeted deletion of miR-126. In addition to vascular defects observed only in the embryo, loss of miR-126 function in the placenta leads to junctional zone hyperplasia at E15.5 at the expense of the labyrinth, reduced placental volume for nutrient exchange and intra-uterine growth restriction of the embryos. Junctional zone hyperplasia results from increased numbers of proliferating glycogen trophoblast (GlyT) progenitors at E13.5 that give rise to an expanded glycogen trophoblast population at E15.5. Transcriptomic profile of miR-126^-/- placentas revealed dysregulation of a large number of GlyT (Prl6a1, Prl7c1, Pcdh12) and trophoblast-specific genes (Tpbpa, Tpbpb, Prld1) and genes with known roles in placental development. We show that miR-126^-/- placentas, but not miR-126^-/- embryos, display aberrant expression of imprinted genes with important roles in glycogen trophoblasts and junctional zone development, including Igf2, H19, Cdkn1c and Phlda2, during mid-gestation. We also show that miR126^-/- placentas display global hypermethylation, including at several imprint control centers. Our findings uncover a novel role for miR-126 in regulating extra-embryonic energy stores, expression of imprinted genes and DNA methylation in the placenta.

LncEGFL7OS regulates human angiogenesis by interacting with MAX at the EGFL7/miR-126 locus

In an effort to identify human endothelial cell (EC)-enriched lncRNAs,~500 lncRNAs were shown to be highly restricted in primary human ECs. Among them, lncEGFL7OS, located in the opposite strand of the EGFL7/miR-126 gene, is regulated by ETS factors through a bidirectional promoter in ECs. It is enriched in highly vascularized human tissues, and upregulated in the hearts of dilated cardiomyopathy patients. LncEGFL7OS silencing impairs angiogenesis as shown by EC/fibroblast co-culture, in vitro/in vivo and ex vivo human choroid sprouting angiogenesis assays, while lncEGFL7OS overexpression has the opposite function. Mechanistically, lncEGFL7OS is required for MAPK and AKT pathway activation by regulating EGFL7/miR-126 expression. MAX protein was identified as a lncEGFL7OS-interacting protein that functions to regulate histone acetylation in the EGFL7/miR-126 promoter/enhancer. CRISPR-mediated targeting of EGLF7/miR-126/lncEGFL7OS locus inhibits angiogenesis, inciting therapeutic potential of targeting this locus. Our study establishes lncEGFL7OS as a human/primate-specific EC-restricted lncRNA critical for human angiogenesis.

Application of Deacetylated Poly-N-Acetyl Glucosamine Nanoparticles for the Delivery of miR-126 for the Treatment of Cecal Ligation and Puncture-Induced Sepsis

Sepsis is an acute inflammatory syndrome in response to infection. In some cases, excessive inflammation from sepsis results in endothelial dysfunction and subsequent increased vascular permeability leading to organ failure. We previously showed that treatment with endothelial progenitor cells, which highly express microRNA-126 (miR-126), improved survival in mice subjected to cecal ligation and puncture (CLP) sepsis. miRNAs are important regulators of gene expression and cell function, play a major role in endothelial homeostasis, and may represent an emerging therapeutic modality. However, delivery of miRNAs to cells in vitro and in vivo is challenging due to rapid degradation by ubiquitous RNases. Herein, we developed a nanoparticle delivery system separately combining deacetylated poly-N-acetyl glucosamine (DEAC-pGlcNAc) polymers with miRNA-126-3p and miRNA-126-5p and testing these combinations in vitro and in vivo. Our results demonstrate that DEAC-pGlcNAc polymers have an appropriate size and zeta potential for cellular uptake and when complexed, DEAC-pGlcNAc protects miRNA from RNase A degradation. Further, DEAC-pGlcNAc efficiently encapsulates miRNAs as evidenced by preventing their migration in an agarose gel. The DEAC-pGlcNAc-miRNA complexes were taken up by multiple cell types and the delivered miRNAs had biological effects on their targets in vitro including pERK and DLK-1. In addition, we found that delivery of DEAC-pGlcNAc alone or DEAC-pGlcNAc:miRNA-126-5p nanoparticles to septic animals significantly improved survival, preserved vascular integrity, and modulated cytokine production. These composite studies support the concept that DEAC-pGlcNAc nanoparticles are an effective platform for delivering miRNAs and that they may provide therapeutic benefit in sepsis.

MicroRNAs in endothelial cell homeostasis and vascular disease

PURPOSE OF REVIEW

Since the first discovery of microRNAs (miRNAs) in 1993, the involvement of miRNAs in different aspects of vascular disease has emerged as an important research field. In this review, we summarize the fundamental roles of miRNAs in controlling endothelial cell functions and their implication with several aspects of vascular dysfunction.

RECENT FINDINGS

MiRNAs have been found to be critical modulators of endothelial homeostasis. The dysregulation of miRNAs has been linked to endothelial dysfunction and the development and progression of vascular disease which and open new opportunities of using miRNAs as potential therapeutic targets for vascular disease.

SUMMARY

Further determination of miRNA regulatory circuits and defining miRNAs-specific target genes remains key to future miRNA-based therapeutic applications toward vascular disease prevention. Many new and unanticipated roles of miRNAs in the control of endothelial functions will assist clinicians and researchers in developing potential therapeutic applications.

The Impact of microRNAs in Breast Cancer Angiogenesis and Progression

OBJECTIVE

The study aims to review the recent data considering the expression profile and the role of microRNAs in breast tumorigenesis, and their impact on -the vital for breast cancer progression- angiogenesis.

METHODS

PubMed was searched for studies focused on data that associate microRNA with breast cancer, using the terms ''breast", "mammary gland", "neoplasia'', "angiogenesis" and ''microRNA'' between 1997-2018.

RESULTS

Aberrant expression of several circulating and tissue miRNAs is observed in human breast neoplasms with the deregulation of several miRNAs having a major participation in breast cancer progression. Angiogenesis seems to be directly affected by either overexpression or down regulation of many miRNAs, defining the overall prognostic rates. Many miRNAs differentially expressed in breast cancer that reveal a key role in suppression - progression and metastasis of breast cancer along with the contribution of the EGF, TNF-a and EGF cytokines. Conclusion Angiogenesis has proven to be vital for tumor development and metastasis while microRNAs are proposed to have multiple biological roles, including participation in immunosuppressive, immunomodulatory and recent studies reveal their implication in angiogenesis and its possible use as prognostic factors in cancer Even though larger studies are needed in order to reach safe conclusions, important steps are made that reveal the connection of serum microRNA expression to the angiogenic course of breast cancer, while miRNAs could be potential prognostic factors for the different breast cancer types.

DICER1 Is Essential for Self-Renewal of Human Embryonic Stem Cells

MicroRNAs (miRNAs) are the effectors of a conserved gene-silencing system with broad roles in post-transcriptional regulation. Due to functional overlaps, assigning specific functions to individual miRNAs has been challenging. DICER1 cleaves pre-miRNA hairpins into mature miRNAs, and previously Dicer1 knockout mouse embryonic stem cells have been generated to study miRNA function in early mouse development. Here we report an essential requirement of DICER1 for the self-renewal of human embryonic stem cells (hESCs). Utilizing a conditional knockout approach, we found that DICER1 deletion led to increased death receptor-mediated apoptosis and failure of hESC self-renewal. We further devised a targeted miRNA screening strategy and uncovered essential pro-survival roles of members of the mir-302-367 and mir-371-373 clusters that bear the seed sequence AAGUGC. This platform is uniquely suitable for dissecting the roles of individual miRNAs in hESC self-renewal and differentiation, which may help us better understand the early development of human embryos.

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Conditional DICER1 knockouts enable the study of its essential requirement in hESCs

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DICER1 deletion leads to increased extrinsic (receptor-mediated) apoptosis

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miRNAs rescue the DICER1 knockout apoptotic phenotype

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This work provides a platform for interrogating miRNA function in hESCs

Circulating miRNAs as biomarkers for early diagnosis of coronary artery disease

INTRODUCTION

Coronary artery disease (CAD) contributes to a huge number of human death worldwide. The early diagnosis can arrest the development of CAD and effectively lower the mortality rate. Recently, circulating miRNAs emerged as CAD biomarkers.

AREAS COVERED

Many efforts were paid to explore early diagnostic biomarkers of CAD. Some proteins have been used as diagnostic golden standard. However, the diagnostic and prognostic value of them is limited. MicroRNAs (miRNAs), a class of small noncoding RNAs, have been illustrated to regulate gene expression. The dysfunction of miRNAs is associated with CAD. MiRNAs presenting stably in body fluids are called circulating miRNAs. The altered expression of specific circulating miRNAs has been discovered in CAD and reported to affect the pathogenesis of CAD. We reviewed the recent data about circulating miRNAs regarding their potential roles in diagnosis, prognosis and therapeutic strategies for CAD. Additionally, we also summarized the current knowledge about circulating miRNA formation and detection.

EXPERT OPINION

Compared with traditional diagnostic tools, circulating miRNAs have many strongpoints, suggesting that circulating miRNAs can serve as promising biomarkers for the early diagnosis and prognosis of CAD.

Endothelial Cell Aging: How miRNAs Contribute?

Endothelial cells (ECs) form monolayers and line the interior surfaces of blood vessels in the entire body. In most mammalian systems, the capacity of endothelial cells to divide is limited and endothelial cells are prone to be senescent. Aging of ECs and resultant endothelial dysfunction lead to a variety of vascular diseases such as atherosclerosis, diabetes mellites, hypertension, and ischemic injury. However, the mechanism by which ECs get old and become senescent and the impact of endothelial senescence on the vascular function are not fully understood. Recent research has unveiled the crucial roles of miRNAs, which are small non-coding RNAs, in regulating endothelial cellular functions, including nitric oxide production, vascular inflammation, and anti-thromboformation. In this review, how senescent-related miRNAs are involved in controlling the functions of ECs will be discussed.

Targetome Analysis Revealed Involvement of MiR-126 in Neurotrophin Signaling Pathway: A Possible Role in Prevention of Glioma Development

OBJECTIVES

For the first time, we used molecular signaling pathway enrichment analysis to determine possible involvement of miR-126 and IRS-1 in neurotrophin pathway.

MATERIALS AND METHODS

In this prospective study, Validated and predicted targets (targetome) of miR-126 were collected following searching miRtarbase (http://mirtarbase.mbc.nctu.edu.tw/) and miRWalk 2.0 databases, respectively. Then, approximate expression of miR-126 targeting in Glioma tissue was examined using UniGene database (http://www.ncbi. nlm.nih.gov/unigene). In silico molecular pathway enrichment analysis was carried out by DAVID 6.7 database (http://david. abcc.ncifcrf.gov/) to explore which signaling pathway is related to miR-126 targeting and how miR-126 attributes to glioma development.

RESULTS

MiR-126 exerts a variety of functions in cancer pathogenesis via suppression of expression of target gene including PI3K, KRAS, EGFL7, IRS-1 and VEGF. Our bioinformatic studies implementing DAVID database, showed the involvement of miR-126 target genes in several signaling pathways including cancer pathogenesis, neurotrophin functions, Glioma formation, insulin function, focal adhesion production, chemokine synthesis and secretion and regulation of the actin cytoskeleton.

CONCLUSIONS

Taken together, we concluded that miR-126 enhances the formation of glioma cancer stem cell probably via down regulation of IRS-1 in neurotrophin signaling pathway.

Development of the renal vasculature

The kidney vasculature has a unique and complex architecture that is central for the kidney to exert its multiple and essential physiological functions with the ultimate goal of maintaining homeostasis. An appropriate development and coordinated assembly of the different vascular cell types and their association with the corresponding nephrons is crucial for the generation of a functioning kidney. In this review we provide an overview of the renal vascular anatomy, histology, and current knowledge of the embryological origin and molecular pathways involved in its development. Understanding the cellular and molecular mechanisms involved in renal vascular development is the first step to advance the field of regenerative medicine.

Differentially expressed miRNAs in premature infants with retinopathy-a bioinformatics analysis

AIM

To reveal the role of miRNAs in retinopathy of prematurity (ROP) by bioinformatics analysis.

METHODS

The raw data of this study came from the researches of Wang et al and Zhao et al who analyzed the microRNA (miRNA) expression profile between ROP and controls. Based on the identified differentially expressed miRNAs, the related target genes, lncRNA and circRNA were predicted. Then we performed functional enrichment analysis to further analyze the functions of target genes.

RESULTS

Hsa-miRNA-128-3p and hsa-miRNA-9-5p showed significantly different expression in both studies. LncRNA of POLDIP2, GAS5, NEFL and UHRF1, circRNA of ZNF280C_hsa_circ_001211 and SIAE_hsa_circ_002083, tar-get gene of QKI showed meaningful differential expression in ROP. Enrichment analysis showed that TGF-β signaling pathway, PI3K-Akt signaling pathway and MAPK signaling pathway might play important roles in the prog-ress of ROP.

CONCLUSION

This research may provide a comprehensive bioinformatics analysis of differentially expressed miRNAs which are possibly involved in ROP.

β-arrestin-biased agonism of β-adrenergic receptor regulates Dicer-mediated microRNA maturation to promote cardioprotective signaling

RATIONALE

MicroRNAs (miRs) are small, non-coding RNAs that function to post-transcriptionally regulate target genes. First transcribed as primary miR transcripts (pri-miRs), they are enzymatically processed by Drosha into premature miRs (pre-miRs) and further cleaved by Dicer into mature miRs. Initially discovered to desensitize β-adrenergic receptor (βAR) signaling, β-arrestins are now well-appreciated to modulate multiple pathways independent of G protein signaling, a concept known as biased signaling. Using the β-arrestin-biased βAR ligand carvedilol, we previously showed that β-arrestin1 (not β-arrestin2)-biased β1AR (not β2AR) cardioprotective signaling stimulates Drosha-mediated processing of six miRs by forming a multi-protein nuclear complex, which includes β-arrestin1, the Drosha microprocessor complex and a single-stranded RNA binding protein hnRNPA1.

OBJECTIVE

Here, we investigate whether β-arrestin-mediated βAR signaling induced by carvedilol could regulate Dicer-mediated miR maturation in the cytoplasm and whether this novel mechanism promotes cardioprotective signaling.

METHODS AND RESULTS

In mouse hearts, carvedilol indeed upregulates three mature miRs, but not their pre-miRs and pri-miRs, in a β-arrestin 1- or 2-dependent manner. Interestingly, carvedilol-mediated activation of miR-466g or miR-532-5p, and miR-674 is dependent on β2ARs and β1ARs, respectively. Mechanistically, β-arrestin 1 or 2 regulates maturation of three newly identified βAR/β-arrestin-responsive miRs (β-miRs) by associating with the Dicer maturation RNase III enzyme on three pre-miRs of β-miRs. Myocardial cell approaches uncover that despite their distinct roles in different cell types, β-miRs act as gatekeepers of cardiac cell functions by repressing deleterious targets.

CONCLUSIONS

Our findings indicate a novel role for βAR-mediated β-arrestin signaling activated by carvedilol in Dicer-mediated miR maturation, which may be linked to its protective mechanisms.

Metazoan MicroRNAs

MicroRNAs (miRNAs) are ∼22 nt RNAs that direct posttranscriptional repression of mRNA targets in diverse eukaryotic lineages. In humans and other mammals, these small RNAs help sculpt the expression of most mRNAs. This article reviews advances in our understanding of the defining features of metazoan miRNAs and their biogenesis, genomics, and evolution. It then reviews how metazoan miRNAs are regulated, how they recognize and cause repression of their targets, and the biological functions of this repression, with a compilation of knockout phenotypes that shows that important biological functions have been identified for most of the broadly conserved miRNAs of mammals.

Mir-126 is a conserved modulator of lymphatic development

Organ homeostasis relies upon cellular and molecular processes that restore tissue structure and function in a timely fashion. Lymphatic vessels help maintain fluid equilibrium by returning interstitial fluid that evades venous uptake back to the circulation. Despite its important role in tissue homeostasis, cancer metastasis, and close developmental origins with the blood vasculature, the number of molecular players known to control lymphatic system development is relatively low. Here we show, using genetic approaches in zebrafish and mice, that the endothelial specific microRNA mir-126, previously implicated in vascular integrity, regulates lymphatic development. In zebrafish, in contrast to mir-126 morphants, double mutants (mir-126a^-/-; mir-126b^-/-, hereafter mir-126^-/-) do not exhibit defects in vascular integrity but develop lymphatic hypoplasia; mir-126^-/- animals fail to develop complete trunk and facial lymphatics, display severe edema and die as larvae. Notably, following MIR-126 inhibition, human Lymphatic Endothelial Cells (hLECs) respond poorly to VEGFA and VEGFC. In this context, we identify a concomitant reduction in Vascular Endothelial Growth Factor Receptor-2 (VEGFR2) and Vascular Endothelial Growth Factor Receptor-3 (VEGFR3, also known as FLT4) expression upon MIR-126 inhibition. In vivo, we further show that flt4^+/- zebrafish embryos exhibit lymphatic defects after mild miR-126 knockdown. Similarly, loss of Mir-126 in Flt4^+/- mice results in embryonic edema and lethality. Thus, our results indicate that miR-126 modulation of Vegfr signaling is essential for lymphatic system development in fish and mammals.

Bone marrow niche trafficking of miR-126 controls the self-renewal of leukemia stem cells in chronic myelogenous leukemia

Leukemia stem cells (LSCs) in individuals with chronic myelogenous leukemia (CML) (hereafter referred to as CML LSCs) are responsible for initiating and maintaining clonal hematopoiesis. These cells persist in the bone marrow (BM) despite effective inhibition of BCR-ABL kinase activity by tyrosine kinase inhibitors (TKIs). Here we show that although the microRNA (miRNA) miR-126 supported the quiescence, self-renewal and engraftment capacity of CML LSCs, miR-126 levels were lower in CML LSCs than in long-term hematopoietic stem cells (LT-HSCs) from healthy individuals. Downregulation of miR-126 levels in CML LSCs was due to phosphorylation of Sprouty-related EVH1-domain-containing 1 (SPRED1) by BCR-ABL, which led to inhibition of the RAN-exportin-5-RCC1 complex that mediates miRNA maturation. Endothelial cells (ECs) in the BM supply miR-126 to CML LSCs to support quiescence and leukemia growth, as shown using mouse models of CML in which Mir126a (encoding miR-126) was conditionally knocked out in ECs and/or LSCs. Inhibition of BCR-ABL by TKI treatment caused an undesired increase in endogenous miR-126 levels, which enhanced LSC quiescence and persistence. Mir126a knockout in LSCs and/or ECs, or treatment with a miR-126 inhibitor that targets miR-126 expression in both LSCs and ECs, enhanced the in vivo anti-leukemic effects of TKI treatment and strongly diminished LSC leukemia-initiating capacity, providing a new strategy for the elimination of LSCs in individuals with CML.

Expression, regulation and function of miR-126 in the mouse choroid vasculature

MicroRNA miR-126 has been shown to be required for proper angiogenesis in several models. However, its expression, regulation and function in the mouse choroid remain unclear. Our previous data has shown that miR-126 expression is enriched in the endothelial cells (ECs) of the mouse choroid. Here we report that a 5.5 kb Egfl7/miR-126 promoter drives the expression of miR-126 in the choroid ECs during choroidal vascular development. The expression of miR-126 in the ECs is regulated by flow stress likely through Krüppel-like transcriptional factors. miR-126^−/− mice show mildly delayed choroidal vascular development, but adult knockout mice develop periphery choroidal vascular lesions. This study suggests that miR-126 is largely dispensable for mouse choroidal development but required for maintaining choroidal vasculature integrity.

EGFL7 reduces CNS inflammation in mouse

Extracellular matrix (ECM) proteins secreted by blood-brain barrier (BBB) endothelial cells (ECs) are implicated in cell trafficking. We discovered that the expression of ECM epidermal growth factor-like protein 7 (EGFL7) is increased in the CNS vasculature of patients with multiple sclerosis (MS), and in mice with experimental autoimmune encephalomyelitis (EAE). Perivascular CD4 T lymphocytes colocalize with ECM-bound EGFL7 in MS lesions. Human and mouse activated T cells upregulate EGFL7 ligand αvβ3 integrin and can adhere to EGFL7 through integrin αvβ3. EGFL7-knockout (KO) mice show earlier onset of EAE and increased brain and spinal cord parenchymal infiltration of T lymphocytes. Importantly, EC-restricted EGFL7-KO is associated with a similar EAE worsening. Finally, treatment with recombinant EGFL7 improves EAE, reduces MCAM expression, and tightens the BBB in mouse. Our data demonstrate that EGFL7 can limit CNS immune infiltration and may represent a novel therapeutic avenue in MS.

Endothelial cells release extracellular matrix components that regulate inflammation. Here the authors demonstrate that the extracellular matrix component epidermal growth factor-like protein 7 regulates inflammation in experimental autoimmune encephalomyelitis in the mouse.

MicroRNAs as predictive biomarkers of response to tyrosine kinase inhibitor therapy in metastatic renal cell carcinoma

Renal cell carcinoma (RCC) accounts for 2%–3% of all malignant tumours. The first-choice treatment in metastatic RCC (mRCC) patients is tyrosine kinase inhibitors (TKIs). Although TKIs may prolong survival of the treated patients who are not primary resistant, almost all of them will eventually develop secondary resistance to the treatment after a progression-free period. To predict treatment response, thus, we need efficient biomarkers for rational indication of TKIs in mRCC. MicroRNAs (miRNAs) not only play important roles in the pathogenesis of many cancers, including RCC but also have been shown to serve as promising diagnostic, prognostic and predictive biomarkers in various cancers. However, the potential of miRNAs to predict response to therapy with TKIs in mRCC has not yet gained sufficient attention. Because personalisation of the TKIs indication in mRCC presents an important unmet medical need, we summarise research on this topic and give an overall insight on the current knowledge in this field.

MicroRNA-126 affects ovarian cancer cell differentiation and invasion by modulating expression of vascular endothelial growth factor

Primary ovarian cancer is the main cause of gynecological cancer-associated mortality. However, the mechanism behind the spread of ovarian cancer requires elucidation. The present study aimed to investigate the effects of microRNA-126 (miR-126) on differentiation and invasion, and its mechanism in primary ovarian cancer. Ovarian cancer SKOV3 cells transfected with LV3-has-miR-126 mimics and LV3-has-miR-126 inhibitor were produced; it was revealedthatLV-miR-126 mimics could induce cell cycle arrest at G₁ phase, suppress cell invasion through Matrigel-coated membranes and downregulate the expression of vascular endothelial growth factor (VEGF). Furthermore, LV-has-miR-126 inhibitor-transfected cells could increase the number of cells in S phase, induce cell invasion and upregulate the expression of VEGF. The present study, to the best of our knowledge, is the first to report that miR-126 may serve tumor suppressor roles by inducing G₁ cell cycle arrest and suppressing invasion in ovarian cancer cells, at least in part by targeting VEGF expression.

miR‑126 is essential for endothelial phenotype expression during endothelial differentiation in adipose‑derived stem cells

The endothelial differentiation of stem cells serves an essential role in vascular development, function and disease. Autograft adipose‑derived stem cells (ADSCs) may be a novel source of cell for use in the study of angiogenesis. microRNA‑126 (miR‑126) has been extensively studied in endothelial cells. However, the effect of miR‑126 on the endothelial differentiation of ADSCs has not been demonstrated. In the present study, it was observed that the expression of miR‑126 was markedly increased during the endothelial differentiation of ADSCs in a time‑dependent manner. The effect of miR‑126 on ADSC differentiation was confirmed by employing up‑ and down‑regulation strategies. The expression of endothelial markers was decreased by miR‑126 inhibitor transfection during endothelial differentiation. The results of the present study suggest that miR‑126 is essential for endothelial phenotype expression, and may promote the progress of endothelial differentiation in ADSCs, providing a novel strategy for modulating vascular formation and function.

MicroRNAs and the response to injury in atherosclerosis

Endothelial cells (ECs) at arterial branching points are physiologically subjected to chronic damage by disturbed blood flow, which triggers a vascular wound healing response. Additional damage by hyperlipid -aemia perturbs this delicate balance of en-dothelial injury and regeneration, and the progressive accumulation of noxious modified lipoproteins leads to macrophage death. Several miRNAs such as miR-92a and miR-712, which modulate EC proliferation and inflammation, are up-regulated by disturbed flow in ECs, and contribute to atherosclerosis. In addition, reduced endothelial levels of miR-126–5p limit the regenerative capacity of ECs, which becomes apparent by insufficient endothelial repair under hyperlipidemic stress. In macrophages, miR-342–5p induces the expression of miR-155 during the progression of atherosclerosis, which promotes inflammatory gene expression and inhibits efferocytosis by targeting Bcl6, thus contributing to necrotic core formation. Deciphering the complex cell- and context-specific effects of miRNAs during vascular wound healing appears essential for the development of miRNA-based therapies of atherosclerosis.

Ghrelin, MicroRNAs, and Critical Limb Ischemia: Hungering for a Novel Treatment Option

Critical limb ischemia (CLI) is the most severe manifestation of peripheral artery disease. It is characterized by chronic pain at rest, skin ulcerations, and gangrene tissue loss. CLI is a highly morbid condition, resulting in a severely diminished quality of life and a significant risk of mortality. The primary goal of therapy for CLI is to restore blood flow to the affected limb, which is only possible by surgery, but is inadvisable in up to 50% of patients. This subset of patients who are not candidates for revascularisation are referred to as "no-option" patients and are the focus of investigation for novel therapeutic strategies. Angiogenesis, arteriogenesis and vasculogenesis are the processes whereby new blood vessel networks form from the pre-existing vasculature and primordial cells, respectively. In therapeutic angiogenesis, exogenous stimulants are administered to promote angiogenesis and augment limb perfusion, offering a potential treatment option for "no option" patients. However, to date, very few clinical trials of therapeutic angiogenesis in patients with CLI have reported clinically significant results, and it remains a major challenge. Ghrelin, a 28-amino acid peptide, is emerging as a potential novel therapeutic for CLI. In pre-clinical models, exogenous ghrelin has been shown to induce therapeutic angiogenesis, promote muscle regeneration, and reduce oxidative stress via the modulation of microRNAs (miRs). miRs are endogenous, small, non-coding ribonucleic acids of ~20-22 nucleotides which regulate gene expression at the post-transcriptional level by either translational inhibition or by messenger ribonucleic acid cleavage. This review focuses on the mounting evidence for the use of ghrelin as a novel therapeutic for CLI, and highlights the miRs which orchestrate these physiological events.

Endothelin signaling regulates mineralization and posttranscriptionally regulates SOST in TMOb cells via miR 126-3p

Previously, our laboratory identified ECE‐1, encoding endothelin‐converting enzyme‐1 (ECE‐1), as a positional candidate for a pleiotropic quantitative trait locus affecting femoral size, shape, and biomechanical performance. We hypothesized that endothelin‐1 (ET‐1) signaling promotes osteogenesis. Exposure of immortalized mouse osteoblast (TMOb) cells to big ET‐1 increased mineralization. Following big ET‐1 treatment, we measured the secretion of insulin‐like‐growth factor‐1 (IGF1), dickkopf‐homolog‐1 protein 1 (DKK1), and sclerostin (SOST). In each case, big ET‐1 signaling changed secretion in a manner that favored increased osteogenic activity. Treatment with ECE‐1, endothelin receptor A (EDNRA), or WNT receptor antagonists inhibited the big ET‐1‐mediated increase in mineralization. In the presence of big ET‐1, message levels of Runx2, Igf1, Dkk1, and Sost are uncoupled from protein production, suggesting posttranscriptional regulation. To evaluate the role of big ET‐1 in normal bone physiology, we inhibited EDNRA signaling during mineralization in the absence of exogenous ET‐1. EDNRA blockade reduced mineralization, decreased IGF1, and increased DKK1 and SOST secretion, responses opposite to those induced by exogenous big ET‐1. Pharmacological and siRNA knockdown to inhibit ECE‐1 reduced mineralization and IGF1 secretion with decreasing DKK1 and decreasing or stable SOST secretion, suggesting a further, unknown role of ECE‐1 in osteoblast maturation. Previously we identified miR 126‐3p as a potential ET‐1‐responsive regulator of SOST in murine cells. Overexpression of miR126‐3p increased mineralization in TMOb cells and decreased SOST secretion. Osteoblasts express the ET‐1 signaling pathway and ET‐1 signaling is necessary for normal osteoblast differentiation and mineralization, acting through regulation of miRs that target osteogenic molecules.

Dysregulated placental microRNAs in Early and Late onset Preeclampsia

INTRODUCTION

To determine the miRNA expression profile in placentas complicated by Preeclampsia (PE) and compare it to uncomplicated pregnancies.

METHODS

Sixteen placentas from women with PE, [11 with early onset PE (EOPE) and 5 with late onset PE (LOPE)], as well as 8 placentas from uncomplicated pregnancies were analyzed using miRNA microarrays. For statistical analyses the MATLAB^® simulation environment was applied. The over-expression of miR-518a-5p was verified using Quantitative Real-Time Polymerase Chain Reaction.

RESULTS

Forty four miRNAs were found dysregulated in PE complicated placentas. Statistical analysis revealed that miR-431, miR-518a-5p and miR-124* were over-expressed in EOPE complicated placentas as compared to controls, whereas miR-544 and miR-3942 were down-regulated in EOPE. When comparing the miRNA expression profile in cases with PE and PE-growth restricted fetuses (FGR), miR-431 and miR-518a-5p were found over-expressed in pregnancies complicated by FGR.

DISCUSSION

Since specific miRNAs can differentiate EOPE and LOPE from uncomplicated placentas, they may be considered as putative PE-specific biomarkers. MiR-518a-5p emerged as a potential diagnostic indicator for EOPE cases as well as for PE-FGR complicated placentas, indicating a potential link to the severity of the disease.

MicroRNA-126a-5p enhances myocardial ischemia-reperfusion injury through suppressing Hspb8 expression

Previously, we found several genes are involved in myocardial ischemia-reperfusion (M-I/R) injury. In this report, we first developed a mouse model of M-I/R injury and demonstrated microRNA-126a-5p was associated with the M-I/R injury by using high-throughput microRNA expression analysis. We further investigated the expression and function of microRNA-126a-5p during mouse M-I/R injury. We observed high expression of microRNA-126a-5p in the M-I/R mice and increased levels of LDH and CK-MB (damage markers) in the serum. H₂O₂ and hypoxia/reoxygenation (H/R) treatment significantly increased the expression of microRNA-126a-5p in H9C2 cells in concentration- and time-dependent manners. Moreover, microRNA-126a-5p overexpression in H9C2 cells inhibited cell viability but increased LDH release and caspase 3 activity. Cardiac function analysis based on the measurements of hemodynamic parameters showed that microRNA-126a-5p expression ablation in M-I/R injured mice led to the reversal of the symptoms caused by M-I/R injury. Transesophageal echocardiography also revealed that the values of LVIDd and LVIDs were decreased while the values of LVFS% and LVEF% were increased in M-I/R injured mice after treatment with microRNA-126a-5p inhibitor, compared with the M-I/R injured mice treated with the control. Bioinformatic analysis demonstrated that Hspb8, a protective protein in myocardium, was the target of microRNA-126a-5p. Thus, these findings indicated that microRNA-126a-5p was up-regulated in mouse M-I/R model and promoted M-I/R injury in vivo through suppressing the expression of Hspb8, which may shed light on the development of potential therapeutic target for M-I/R injury.

The eutheria-specific miR-290 cluster modulates placental growth and maternal-fetal transport

The vertebrate-specific ESCC microRNA family arises from two genetic loci in mammals: miR-290/miR-371 and miR-302. The miR-302 locus is found broadly among vertebrates, whereas the miR-290/miR-371 locus is unique to eutheria, suggesting a role in placental development. Here, we evaluate that role. A knock-in reporter for the mouse miR-290 cluster is expressed throughout the embryo until gastrulation, when it becomes specifically expressed in extraembryonic tissues and the germline. In the placenta, expression is limited to the trophoblast lineage, where it remains highly expressed until birth. Deletion of the miR-290 cluster gene (Mirc5) results in reduced trophoblast progenitor cell proliferation and a reduced DNA content in endoreduplicating trophoblast giant cells. The resulting placenta is reduced in size. In addition, the vascular labyrinth is disorganized, with thickening of the maternal-fetal blood barrier and an associated reduction in diffusion. Multiple mRNA targets of the miR-290 cluster microRNAs are upregulated. These data uncover a crucial function for the miR-290 cluster in the regulation of a network of genes required for placental development, suggesting a central role for these microRNAs in the evolution of placental mammals.

Epigenetic Modification of MicroRNA-200b Contributes to Diabetic Vasculopathy

Hyperglycemia (HG) induces genome-wide cytosine demethylation. Our previous work recognized miR-200b as a critical angiomiR, which must be transiently downregulated to initiate wound angiogenesis. Under HG, miR-200b downregulation is not responsive to injury. Here, we demonstrate that HG may drive vasculopathy by epigenetic modification of a miR promoter. In human microvascular endothelial cells (HMECs), HG also lowered DNA methyltransferases (DNMT-1 and DNMT-3A) and compromised endothelial function as manifested by diminished endothelial nitric oxide (eNOS), lowered LDL uptake, impaired Matrigel tube formation, lower NO production, and compromised VE-cadherin expression. Bisulfite-sequencing documented HG-induced miR-200b promoter hypomethylation in HMECs and diabetic wound-site endothelial cells. In HMECs, HG compromised endothelial function. Methyl donor S-adenosyl-L-methionine (SAM) corrected miR-200b promoter hypomethylaton and rescued endothelial function. In vivo, wound-site administration of SAM to diabetic mice improved wound perfusion by limiting the pathogenic rise of miR-200b. Quantitative stable isotope labeling by amino acids in cell culture (SILAC) proteomics and ingenuity pathway analysis identified HG-induced proteins and principal clusters in HMECs sensitive to the genetic inhibition of miR-200b. This work presents the first evidence of the miR-200b promoter methylation as a critical determinant of diabetic wound angiogenesis.

Antioxidant Therapeutic Strategies for Cardiovascular Conditions Associated with Oxidative Stress

Oxidative stress (OS) refers to the imbalance between the generation of reactive oxygen species (ROS) and the ability to scavenge these ROS by endogenous antioxidant systems, where ROS overwhelms the antioxidant capacity. Excessive presence of ROS results in irreversible damage to cell membranes, DNA, and other cellular structures by oxidizing lipids, proteins, and nucleic acids. Oxidative stress plays a crucial role in the pathogenesis of cardiovascular diseases related to hypoxia, cardiotoxicity and ischemia-reperfusion. Here, we describe the participation of OS in the pathophysiology of cardiovascular conditions such as myocardial infarction, anthracycline cardiotoxicity and congenital heart disease. This review focuses on the different clinical events where redox factors and OS are related to cardiovascular pathophysiology, giving to support for novel pharmacological therapies such as omega 3 fatty acids, non-selective betablockers and microRNAs.

The association of miR-126-3p, miR-126-5p and miR-664-3p expression profiles with outcomes of patients with metastatic colorectal cancer treated with bevacizumab

MicroRNAs regulate the expression of genes involved in several important cancer-related processes including cell adhesion, proliferation, and tumour angiogenesis. Bevacizumab is routinely used in the treatment of patients with metastatic colorectal cancer, but, so far, no reliable biomarker predicting response to bevacizumab has been established. The aim of our retrospective study was to evaluate the association of miR-126-3p, miR-126-5p and miR-664-3p tumour expression levels with outcomes of patients with metastatic colorectal cancer treated with bevacizumab. The study included 63 patients. For the assessment of microRNA expression, gene-specific TaqMan assays were used. The median progression-free survival and overall survival for patients with low tumour expression of miR-126-3p were 8.8 and 20.6 months versus 13.5 months and median overall survival was not reached for patients with high expression ( p = 0.0064 and p = 0.0027), respectively. The median progression-free survival and overall survival for patients with low tumour expression of miR-126-5p were 9.0 and 22.2 months versus 12.0 and 23.4 months for patients with high expression ( p = 0.2113 and 0.6858), respectively. The median progression-free survival and overall survival for patients with low tumour expression of miR-664-3p were 9.1 and 22.5 months versus 8.8 and 23.4 months for patients with high expression ( p = 0.2542 and p = 0.1922), respectively. The multivariable Cox proportional hazards model revealed that miR-126-3p expression was significantly associated with progression-free survival (hazard ratio = 0.28, p = 0.0053) and also with overall survival (hazard ratio = 0.18, p = 0.0046). In conclusion, the results of this study suggest that the expression of miR-126-3p in the tumour tissue was associated with outcome of metastatic colorectal cancer patients treated with bevacizumab.

MicroRNA as Therapeutic Targets for Chronic Wound Healing

Wound healing is a highly complex biological process composed of three overlapping phases: inflammation, proliferation, and remodeling. Impairments at any one or more of these stages can lead to compromised healing. MicroRNAs (miRs) are non-coding RNAs that act as post-transcriptional regulators of multiple proteins and associated pathways. Thus, identification of the appropriate miR involved in the different phases of wound healing could reveal an effective third-generation genetic therapy in chronic wound care. Several miRs have been shown to be upregulated or downregulated during the wound healing process. This article examines the biological processes involved in wound healing, the miR involved at each stage, and how expression levels are modulated in the chronic wound environment. Key miRs are highlighted as possible therapeutic targets, either through underexpression or overexpression, and the healing benefits are interrogated. These are prime miR candidates that could be considered as a gene therapy option for patients suffering from chronic wounds. The success of miR as a gene therapy, however, is reliant on the development of an appropriate delivery system that must be designed to overcome both extracellular and intracellular barriers.

Urinary Excretion of MicroRNA-126 Is a Biomarker for Hemangioma Proliferation

BACKGROUND

Hemangiomas are unique endothelial cell tumors that involute spontaneously, which makes interpreting their response to therapies difficult. The objective of this work was to identify a potential biomarker in the urine of children with infantile hemangiomas that would facilitate testing new therapies.

METHODS

A prospective longitudinal study in children with hemangiomas and age-matched healthy controls was performed to determine whether microRNA-126, which is highly abundant in fetal endothelial cells, was more abundant in the urine of affected children. Prospective ultrasound measurements of hemangioma size and blood flow velocity were obtained as secondary endpoints to document longitudinal changes in untreated hemangiomas.

RESULTS

Urinary microRNA-126 levels were significantly elevated in children with proliferating hemangiomas, and relative levels of urinary microRNA abundance correlated with hemangioma size. Hemangiomas had elevated levels of microRNA abundance compared with healthy controls. Ultrasound data revealed that hemangioma proliferation typically stopped between 6 and 9 months of age. When hemangioma proliferation stopped, urinary microRNA-126 levels in children with hemangiomas dropped to levels observed in healthy age-matched controls.

CONCLUSIONS

These are the first reported results to identify a potential microRNA biomarker in the urine of children with hemangiomas. Measurement of urinary levels of microRNA-126 could potentially be used to monitor hemangioma response to therapies.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, II.

Altered feto-placental vascularization, feto-placental malperfusion and fetal growth restriction in mice with Egfl7 loss of function

EGFL7 is a secreted angiogenic factor produced by embryonic endothelial cells. To understand its role in placental development, we established a novel Egfl7 knockout mouse. The mutant mice have gross defects in chorioallantoic branching morphogenesis and placental vascular patterning. Microangiography and 3D imaging revealed patchy perfusion of Egfl7^-/- placentas marked by impeded blood conductance through sites of narrowed vessels. Consistent with poor feto-placental perfusion, Egfl7 knockout resulted in reduced placental weight and fetal growth restriction. The placentas also showed abnormal fetal vessel patterning and over 50% reduction in fetal blood space. In vitro, placental endothelial cells were deficient in migration, cord formation and sprouting. Expression of genes involved in branching morphogenesis, Gcm1, Syna and Synb, and in patterning of the extracellular matrix, Mmrn1, were temporally dysregulated in the placentas. Egfl7 knockout did not affect expression of the microRNA embedded within intron 7. Collectively, these data reveal that Egfl7 is crucial for placental vascularization and embryonic growth, and may provide insight into etiological factors underlying placental pathologies associated with intrauterine growth restriction, which is a significant cause of infant morbidity and mortality.

miRNAs: micro-managers of anticancer combination therapies

Angiogenesis is one of the hallmarks of cancer progression and as such has been considered a target of therapeutic interest. However, single targeted agents have not fully lived up to the initial promise of anti-angiogenic therapy. Therefore, it has been suggested that combining therapies and agents will be the way forward in the oncology field. In recent years, microRNAs (miRNAs) have received considerable attention as drivers of tumor development and progression, either acting as tumor suppressors or as oncogenes (so-called oncomiRs), as well as in the process of tumor angiogenesis (angiomiRs). Not only from a functional, but also from a therapeutic view, miRNAs are attractive tools. Thus far, several mimics and antagonists of miRNAs have entered clinical development. Here, we review the provenance and promise of miRNAs as targets as well as therapeutics to contribute to anti-angiogenesis-based (combination) treatment of cancer.

MicroRNA miR-126-5p Enhances the Inflammatory Responses of Monocytes to Lipopolysaccharide Stimulation by Suppressing Cylindromatosis in Chronic HIV-1 Infection

Persistent immune activation during chronic human immunodeficiency virus type 1 (HIV-1) infection facilitates immune dysfunction and thereby fuels disease progression. The translocation of bacterial derivatives into blood and the hyperinflammatory responsiveness of monocytes have been considered important causative factors for persistent immune activation. Whether microRNAs (miRNAs) are involved in regulating monocyte-mediated inflammatory responses during chronic HIV-1 infection remains elusive. In this study, we show that miR-126-5p functions as a positive regulator of monocyte-mediated inflammatory responses. Significantly increased miRNA miR-126-5p and decreased cylindromatosis (CYLD) were observed in primary monocytes from chronic HIV-1 patients. Inhibition of miR-126-5p in monocytes from chronic HIV-1 patients attenuated the responsiveness of these cells to lipopolysaccharide (LPS) stimulation. Gain-of-function assays confirmed that miR-126-5p could downregulate CYLD, which in turn caused an upregulation of phosphorylation of JNK protein (pJNK) and enhanced inflammatory responses of monocytes to LPS stimulation. Overall, miR-126-5p upregulates the responsiveness of monocytes to LPS stimulation in chronic HIV-1 infection, and the suppression of miR-126-5p and the promotion of CYLD expression in primary monocytes may represent a practical immune intervention strategy to contain persistent inflammation in chronic HIV-1 infection.IMPORTANCE Monocyte-mediated hyperinflammatory responses during chronic HIV-1 infection are important causative factors driving AIDS progression; however, the underlying mechanism has not been fully addressed. We demonstrated that miR-126-5p, one of the most upregulated miRNAs during chronic HIV-1 infection, could enhance the inflammatory responses of monocytes to LPS by suppressing the inhibitory protein CYLD and thereby unleashing the expression of pJNK in the LPS/Toll-like receptor 4/mitogen-activated protein kinase pathway. This observation reveals a new mechanism for HIV-1 pathogenesis, which could be targeted by immune intervention.

Effects of microRNA-126 on cell proliferation, apoptosis and tumor angiogenesis via the down-regulating ERK signaling pathway by targeting EGFL7 in hepatocellular carcinoma

This study intends to explore the effects of microRNA-126 (miR-126) on cell proliferation, apoptosis, and tumor angiogenesis in hepatocellular carcinoma (HCC) by regulating epidermal growth factor-like domain 7 (EGFL7) through extracellular signal-regulated kinase (ERK) signaling. HCC tissues and adjacent normal tissues were obtained from 184 HCC patients. HCC cells were separately transfected with recombinant plasmids. Western blotting and qRT-PCR were applied to detect miR-126 and EGFL7, ERK, Fas/FasL, Bcl-2, Caspase mRNA and protein levels. CCK8 and TUNEL were performed to determinate cell proliferation and apoptosis. Flow cytometry was used to analyze cell cycle distribution. Rats model of HCC was constructed, and tumor weight and the number of new blood vessels were recorded after 3 weeks of tumor transplantation. Compared with the adjacent normal tissues, HCC tissues exhibited lower miR-126 expression, and higher EGFL7, and ERK mRNA and protein levels. Overexpression of miR-126 in HCC cell lines suppressed EGFL7, ERK, Bcl-2, and P-ERK, and increased apoptotic-associated proteins Fas/FasL and Caspase-3, and it inhibited cell proliferation and induced cell apoptosis. Overexpression of miR-126 in nude mice resulted in reduced tumor weight and less new blood vessels in tumors. The inhibition of miR-126 decreased cell apoptosis, and enhanced cell proliferation and tumor angiogenesis. This study demonstrates that miR-126 might decrease cell proliferation, induce apoptosis, and inhibit tumor angiogenesis in HCC by inhibiting EGFL7 via down-regulating the ERK signaling pathway.

MiR-126 overexpression inhibits high glucose-induced migration and tube formation of rhesus macaque choroid-retinal endothelial cells by obstructing VEGFA and PIK3R2

AIM

The aims of this study are to investigate the relative regulation between miR-126 and VEGF/PI3K/AKT signaling pathway in retinal vascular endothelial cells.

METHODS

Rhesus macaque choroid-retinal endothelial cell line (RF/6A) cells were cultured in high glucose to imitate the conditions occurring in DR. First, we detected the expression of miR-126, VEGFA and PIK3R2 in RF/6A cells on the condition of high glucose by q-PCR and western blot. Then, after addition of miR-126 mimics and miR-126 inhibitor, we investigated the function of miR-126 in RF/6A cells by scratch wound, Transwell migration and tube formation assays, and the effect of miR-126 on the expression of VEGFA, PIK3R2 and AKT. Moreover, bioinformatics analysis and luciferase array were used to confirm the direct or specific regulation of miR-126 to VEGFA or PIK3R2.

RESULTS

Here, first, we found that high glucose could induce the decrease of miR-126 and the increase of VEGFA and PIK3R2 in RF/6A. Then, by scratch wound, Transwell migration and tube formation assays, we found that miR-126 overexpression could inhibit the migration and sprouting of RF/6A cells induced by high glucose, while knockdown of miR-126 led to the opposite results. Moreover, overexpression of miR-126 inhibited the increased expression of VEGFA, PIK3R2, SDF-1α, VCAM-1, and SPRED1, and the activation of AKT1 induced by high glucose and miR-126 inhibitor caused the opposite results which were determined by q-PCR and western blot. In addition, by luciferase assay, we found that miR-126 could directly negatively regulate VEGFA and PIK3R2.

CONCLUSION

Our results suggest that miR-126 overexpression inhibits the migration and sprouting of RF/6A cells induced by high glucose which might possibly be by blocking VEGFA and PIK3R2 in the VEGF/PI3K/AKT signaling pathway.

The Influence of Extracellular RNA on Cell Behavior in Health, Disease and Regeneration

PURPOSE OF REVIEW

An overview of the role of extracellular RNAs (exRNA) in the regulation of homeostasis, disease progression, and regeneration is provided herein. Several exRNAs have been identified as potential biomarkers for disease and disease progression. In addition, the potential of exRNAs as a therapeutic modality is discussed.

RECENT FINDINGS

Fibrotic diseases of the lung, liver, and heart, among other organs share a number of identical exRNAs which play key roles in disease pathogenesis. Though regeneration is limited to only a few tissues in humans, small RNAs (e.g. microRNA) have been shown to be involved in the regenerative process of tissues such as liver and bone. The regulation of healing versus disease appears to be balanced by small RNAs. Because small RNAs are critical to health, they are being investigated as drug targets in multiple ongoing clinical trials. Preclinical studies suggest that promoting or blocking specific small RNAs can provide a novel therapeutic approach.

SUMMARY

exRNA can be utilized for both detection and treatment of disease. Natural and synthetic RNA carriers are being investigated as delivery methods for small RNA molecules. Current and future investigations are likely to lead to expanded applications for exRNAs.

MicroRNAs: Impaired vasculogenesis in metal induced teratogenicity

Certain metals have been known for their toxic effects on embryos and fetal development. The vasculature in early pregnancy is extremely dynamic and plays an important role in organogenesis. Nascent blood vessels in early embryonic life are considered to be a primary and delicate target for many teratogens since the nascent blood islands follow a tightly controlled program to form vascular plexus around and inside the embryo for resourcing optimal ingredients for its development. The state of the distribution of toxic metals, their transport mechanisms and the molecular events by which they notch extra-embryonic and embryonic vasculatures are illustrated. In addition, pharmacological aspects of toxic metal induced teratogenicity have also been portrayed. The work reviewed state of the current knowledge of specific role of microRNAs (miRNAs) that are differentially expressed in response to toxic metals, and how they interfere with the vasculogenesis that manifests into embryonic anomalies.

Protective role of microRNA-126 in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a disease associated with high mortality and morbidity. MicroRNAs (miRNAs) are important regulators of translation and have been reported to be associated with the pathogenesis of numerous cerebrovascular diseases, including ICH. The present study explored the role of miRNA (miR)‑126 in ICH. Adult male Wistar rats were randomly assigned to ICH model and sham groups. ICH was induced by intracerebral injection of collagenase. The mRNA expression levels of miR‑126 in the two groups were determined. The miR‑126 lentivirus expression vector pWPXL‑miR‑126 or negative control vector was then constructed and delivered via intraparenchymal injection. Following transduction, behavioral testing (rotarod and limb placement tests), relative hemorrhagic lesion size, apoptotic cells and protein levels of vascular endothelial growth factor (VEGF)‑A and caspase‑3 were determined. The relative expression levels of miR‑126 were significantly decreased in the ICH group compared to the sham group (P=0.026). Overexpression of miR‑126 significantly improved the relative duration of stay on the rotarod at day 2 (P=0.029) and 3 (P=0.033), and statistically reduced the deficit score (P=0.036), the relative size of hemorrhagic lesion (P=0.019) and the number of apoptotic cortical neurons (P=0.024) compared with the sham group. Additionally, the protein levels of VEGF‑A were significantly elevated, however levels of caspase‑3 were downregulated by overexpression of miR‑126 compared with the negative control group. MiR‑126 therefore exhibits a protective role in ICH. Overexpression of miR‑126 protects against ICH, and may be involved in the process of angiogenesis and exhibit an anti-apoptotic effect.

MiR-126 Affects Brain-Heart Interaction after Cerebral Ischemic Stroke

Cardiovascular diseases are approximately three times higher in patients with neurological deficits than in patients without neurological deficits. MicroRNA-126 (MiR-126) facilitates vascular remodeling and decreases fibrosis and is emerging as an important factor in the pathogenesis of cardiovascular diseases and cerebral stroke. In this study, we tested the hypothesis that decreased miR-126 after ischemic stroke may play an important role in regulating cardiac function. Wild-type (WT), specific conditional-knockout endothelial cell miR-126 (miR-126^EC-/-), and miR-126 knockout control (miR-126^fl/fl) mice were subjected to distal middle cerebral artery occlusion (dMCAo) (n = 10/group). Cardiac hemodynamics and function were measured using transthoracic Doppler echocardiography. Mice were sacrificed at 28 days after dMCAo. WT mice subjected to stroke exhibited significantly decreased cardiac ejection fraction and increased myocyte hypertrophy, fibrosis as well as increased heart inflammation, infiltrating macrophages, and oxidative stress compared to non-stroke animals. Stroke significantly decreased serum and heart miR-126 expression and increased miR-126 target genes, vascular cell adhesion protein-1, and monocyte chemotactic protein-1 gene, and protein expression in the heart compared to non-stroke mice. MiR-126^EC-/- mice exhibited significantly decreased cardiac function and increased cardiomyocyte hypertrophy, fibrosis, and inflammatory factor expression after stroke compared to miR-126^fl/fl stroke mice. Exosomes derived from endothelial cells of miR-126^EC-/- (miR-126^EC-/-EC-Exo) mice exhibited significantly decreased miR-126 expression than exosomes derived from miR-126^fl/fl (miR-126^fl/fl-EC-Exo) mice. Treatment of cardiomyocytes subjected to oxygen glucose deprivation with miR-126^fl/fl-EC-Exo exhibited significantly decreased hypertrophy than with miR-126^EC-/-EC-Exo treatment. Ischemic stroke directly induces cardiac dysfunction. Decreasing miR-126 expression may contribute to cardiac dysfunction after stroke in mice.

Lipoxin A4 stimulates endothelial miR-126-5p expression and its transfer via microvesicles

The proresolution lipid mediator lipoxin (LX)A₄ bestows protective bioactions on endothelial cells. We examined the impact of LXA₄ on transcellular endothelial signaling via microRNA (miR)-containing microvesicles. We report LXA₄ inhibition of MV release by TNF-α-treated HUVECs, associated with the down-regulation of 18 miR in endothelial microvesicles (EMVs) and the up-regulation of miR-126-5p, both in HUVECs and in EMVs. LXA₄ up-regulated miR-126-5p by ∼5-fold in HUVECs and promoted a release of microvesicles (LXA₄-EMVs) that enhanced miR-126-5p by ∼7-fold in recipient HUVECs. In these cells, LXA₄-EMVs abrogated the up-regulation of VCAM-1, induced in recipient HUVECs by EMVs released by untreated or TNF-α-treated HUVECs. LXA₄-EMVs also reduced by ∼40% the expression of SPRED1, which we validated as an miR-126-5p target, whereas they stimulated monolayer repair in an in vitro wound assay. This effect was lost when the EMVs were depleted of miR-126-5p. These results provide evidence that changes in miR expression and microvesicle packaging and transfer represent a mechanism of action of LXA₄, which may be relevant in vascular biology and inflammation.-Codagnone, M., Recchiuti, A., Lanuti, P., Pierdomenico, A. M., Cianci, E., Patruno, S., Mari, V. C., Simiele, F., Di Tomo, P., Pandolfi, A., Romano, M. Lipoxin A₄ stimulates endothelial miR-126-5p expression and its transfer via microvesicles.

Down-regulation of proangiogenic microRNA-126 and microRNA-132 are early modulators of diabetic cardiac microangiopathy

AIM

Microangiopathy due to endothelial dysfunction is a major contributing factor to the development of diabetes-induced cardiovascular disease (CVD). Dysregulation of endothelial-specific microRNAs (miRs) is correlated with impaired angiogenesis and cell survival. We investigated the profile of two angiomiRs, miR-126, and miR-132, in the plasma of type 2 diabetic individuals without any known history of CVD as well as in the cardiac tissues collected from diabetics undergoing cardiac surgery.

METHODS AND RESULTS

The presence of diabetes alone significantly decreased both angiomiRs in the plasma and the myocardium. The down-regulation of angiomiRs was also associated with reduced capillaries and arterioles and increased endothelial cell apoptosis, the hallmark of microangiopathy. Importantly, a time course study in a type 2 diabetic mouse model confirmed that the down-regulation of angiomiRs preceded endothelial apoptosis as well as alterations in the density of the microvasculature. Finally, therapeutic overexpression of both angiomiRs in diabetic aortic rings and human umbilical vein endothelial cells exposed to high glucose (HG) abrogated the deleterious effects of diabetes and HG on cell survival and proliferation and restored their angiogenic potential.

CONCLUSIONS

These novel findings demonstrate that the down-regulation of angiomiRs is a major underlying mechanism for the development of microangiopathy in diabetic hearts. Therefore, therapeutic restoration of angiomiRs could become a potential approach to combat the cardiovascular complications of diabetes.

Differentially expressed miRNAs in oxygen‑induced retinopathy newborn mouse models

The present study aimed to identify microRNAs (miRNAs) involved in regulating retinal neovascularization and retinopathy of prematurity (ROP). A total of 80 healthy C57BL/6 neonatal mice were randomly divided into the oxygen-induced retinopathy (OIR) group (n=40), in which 7-day-old mice were maintained in 75% oxygen conditions for 5 days, or the control group (n=40). Following collection of retinal tissue, retinal angiography and hematoxylin and eosin (H&E) staining were performed. Total RNA was also extracted from retinal tissue, and miRNA microarrays and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were performed to identify differentially expressed miRNAs in the two groups. Retinal angiography and H&E staining revealed damage to retinas in the OIR group. Compared with the control group, 67 miRNAs were differentially expressed in the OIR group, of which 34 were upregulated and 33 were downregulated. Of these differentially expressed miRNAs, 32 exhibited a fold change ≥2, of which 21 were upregulated and 11 were downregulated. The results of RT-qPCR for miR-130a-3p and miR-5107-5p were in accordance with those of the miRNA microarray. The newly identified miRNAs may be important in the development of ROP, and may provide a basis for future research into the mechanisms of ROP.

MicroRNAs as regulators of endothelial cell functions in cardiometabolic diseases

Endothelial cells (ECs) provide nutrients and oxygen essential for tissue homeostasis. Metabolic imbalances and other environmental stimuli, like cytokines or low shear stress, trigger endothelial inflammation, increase permeability, compromise vascular tone, promote cell proliferation, and ultimately cause cell death. These factors contribute to EC dysfunction, which is crucial in the development of cardiometabolic diseases. microRNAs (miRNAs) are small non-coding RNAs that have important functions in the regulation of ECs. In the present review, we discuss the role of miRNAs in various aspects of EC pathology in cardiometabolic diseases like atherosclerosis, type 2 diabetes, obesity, and the metabolic syndrome, and in complication of those pathologies, like ischemia. We also discuss the potential therapeutic applications of miRNAs in promoting angiogenesis and neovascularization in tissues where the endothelium is damaged in different cardiometabolic diseases. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

Fabrication of hydroxyapatite/chitosan composite hydrogels loaded with exosomes derived from miR-126-3p overexpressed synovial mesenchymal stem cells for diabetic chronic wound healing

The exploration of an effective diabetic chronic wound healing process still remains a great challenge. Herein, we used gene overexpression technology to obtain synovial mesenchymal stem cells (SMSCs) and the miR-126-3p highly expressed SMSCs (SMSCs-126). The exosomes derived from miR-126-3p overexpressed SMSCs (SMSCs-126-Exos) with a particle size of 85 nm were encapsulated in hydroxyapatite/chitosan (HAP-CS) composite hydrogels (HAP-CS-SMSCs-126-Exos) as wound dressings. The SMSCs-126-Exos, CS and low-crystallinity HAP nanorods with a length of 200 nm and a diameter of 50 nm are uniformly dispersed within the whole composite hydrogel. The HAP-CS-SMSCs-126-Exos possess the controlled release property of SMSCs-126-Exos for at least 6 days. The released SMSCs-126-Exos nanoparticles stimulate the proliferation and migration of human dermal fibroblasts and human dermal microvascular endothelial cells (HMEC-1). At the same time, the migration and capillary-network formation of HMEC-1 are promoted through the activation of MAPK/ERK and PI3K/AKT. In vivo tests demonstrate that the HAP-CS-SMSCs-126-Exos successfully promote wound surface re-epithelialization, accelerate angiogenesis, and expedite collagen maturity due to the presence of HAP, CS and SMSCs-126-Exos. Therefore, the HAP-CS-SMSCs-126-Exos possess great potential application for diabetic chronic wound healing, and especially provide the possibility of using exosomes derived from modified cells as a new approach to bring wonderful functionality and controllability in future chronic wound therapy.

miR-216 and miR-217 expression is reduced in transgenic mouse models of pancreatic adenocarcinoma, knockout of miR-216/miR-217 host gene is embryonic lethal

Mice harboring a G12D activating Kras mutation are among the most heavily studied models in the field of pancreatic adenocarcinoma (PDAC) research. miRNAs are differentially expressed in PDAC from patients and mouse models of PDAC. To better understand the relationship that Kras activation has on miRNA expression, we profiled the expression of 629 miRNAs in RNA isolated from the pancreas of control, young, and old P48^+/Cre;LSL-KRAS^G12D as well as PDX-1-Cre;LSL-KRAS^G12D mice. One hundred of the differentially expressed miRNAs had increased expression in the advanced disease (old) P48^+/Cre;LSL-KRAS^G12D compared to wild-type mice. Interestingly, the expression of three miRNAs, miR-216a, miR-216b, and miR-217, located within a ∼30-kbp region on 11qA3.3, decreased with age (and phenotype severity) in these mice. miR-216/-217 expression was also evaluated in another acinar-specific ELa-Kras^G12D mouse model and was downregulated as well. As miR-216/-217 are acinar enriched, reduced in human PDAC and target KRAS, we hypothesized that they may maintain acinar differentiation or represent tumor suppressive miRNAs. To test this hypothesis, we deleted a 27.9-kbp region of 11qA3.3 containing the miR-216/-217 host gene in the mouse's germ line. We report that germ line deletion of this cluster is embryonic lethal in the mouse. We estimate that lethality occurs shortly after E9.5. qPCR analysis of the miR-216b and miR-217 expression in the heterozygous animals showed no difference in expression, suggesting haplosufficiency by some type of compensatory mechanism. We present the differential miRNA expression in Kras^G12D transgenic mice and report lethality from deletion of the miR-216/-217 host gene in the mouse's germ line.