MicroRNA-19b promotes macrophage cholesterol accumulation and aortic atherosclerosis by targeting ATP-binding cassette transporter A1. Atherosclerosis. 2014;236:215-226. [PMID: 25084135 DOI: 10.1016/j.atherosclerosis.2014.07.005]

Monocytic microRNAs-Novel targets in atherosclerosis therapy

Atherosclerosis is a chronic proinflammatory disease of the vascular wall resulting in narrowing of arteries due to plaque formation, thereby causing reduced blood supply that is the leading cause for diverse end-organ damage with high mortality rates. Monocytes/macrophages, activated by elevated circulating lipoproteins, are significantly involved in the formation and development of atherosclerotic plaques. The imbalance between proinflammatory and anti-inflammatory macrophages, arising from dysregulated macrophage polarization, appears to be a driving force in this process. Proatherosclerotic processes acting on monocytes/macrophages include accumulation of cholesterol in macrophages leading to foam cell formation, as well as dysfunctional efferocytosis, all of which contribute to the formation of unstable plaques. In recent years, microRNAs (miRs) were identified as factors that could modulate monocyte/macrophage function and may therefore interfere with the atherosclerotic process. In this review, we present effects of monocyte/macrophage-derived miRs on atherosclerotic processes in order to reveal new treatment options using miRmimics or antagomiRs.

Functional significance of cholesterol metabolism in cancer: from threat to treatment

Cholesterol is an essential structural component of membranes that contributes to membrane integrity and fluidity. Cholesterol homeostasis plays a critical role in the maintenance of cellular activities. Recently, increasing evidence has indicated that cholesterol is a major determinant by modulating cell signaling events governing the hallmarks of cancer. Numerous studies have shown the functional significance of cholesterol metabolism in tumorigenesis, cancer progression and metastasis through its regulatory effects on the immune response, ferroptosis, autophagy, cell stemness, and the DNA damage response. Here, we summarize recent literature describing cholesterol metabolism in cancer cells, including the cholesterol metabolism pathways and the mutual regulatory mechanisms involved in cancer progression and cholesterol metabolism. We also discuss various drugs targeting cholesterol metabolism to suggest new strategies for cancer treatment.

Epigenetic modifications as therapeutic targets in atherosclerosis: a focus on DNA methylation and non-coding RNAs

Significant progress in the diagnosis and treatment of cardiovascular disease (CVD) has been made in the past decade, yet it remains a leading cause of morbidity and mortality globally, claiming an estimated 17.9 million deaths per year. Although encompassing any condition that affects the circulatory system, including thrombotic blockage, stenosis, aneurysms, blood clots and arteriosclerosis (general hardening of the arteries), the most prevalent underlying hallmark of CVD is atherosclerosis; the plaque-associated arterial thickening. Further, distinct CVD conditions have overlapping dysregulated molecular and cellular characteristics which underlie their development and progression, suggesting some common aetiology. The identification of heritable genetic mutations associated with the development of atherosclerotic vascular disease (AVD), in particular resulting from Genome Wide Association Studies (GWAS) studies has significantly improved the ability to identify individuals at risk. However, it is increasingly recognised that environmentally-acquired, epigenetic changes are key factors associated with atherosclerosis development. Increasing evidence suggests that these epigenetic changes, most notably DNA methylation and the misexpression of non-coding, microRNAs (miRNAs) are potentially both predictive and causal in AVD development. This, together with their reversible nature, makes them both useful biomarkers for disease and attractive therapeutic targets potentially to reverse AVD progression. We consider here the association of aberrant DNA methylation and dysregulated miRNA expression with the aetiology and progression of atherosclerosis, and the potential development of novel cell-based strategies to target these epigenetic changes therapeutically.

c-Jun-mediated miR-19b expression induces endothelial barrier dysfunction in an in vitro model of hemorrhagic shock

BACKGROUND

Our previous data demonstrated that miR-19b expression was increased in human lung microvascular endothelial cells in-vitro-, in-vivo and in patients with hemorrhagic shock, leading to a decrease in syndecan-1 mRNA and protein and resulting in loss of endothelial barrier function. However, the mechanism underlying increased miR-19b expression remains unclear. The objective of the current study was to determine if c-Jun mediates the early responsive microRNA, miR-19b, to cause endothelial barrier dysfunction.

METHOD

Human lung microvascular endothelial cells (HLMEC) or HEK293T cells were transfected with c-Jun overexpressing vector, c-Jun siRNA, miR-19b promoter vector, miR-19b mutated promoter vector, miR-19b oligo inhibitor, then subjected to hypoxia/reoxygenation as in-vitro model of hemorrhagic shock. Levels of protein, miRNA, and luciferase activity were measured. Transwell permeability of endothelial monolayers were also determined. Plasma levels of c-Jun were measured in injured patients with hemorrhagic shock.

RESULT

Hypoxia/reoxygenation induced primary (pri-)miR-19b, mature miR-19b, and c-Jun expression over time in a comparable timeframe. c-Jun silencing by transfection with its specific siRNA reduced both pri-miR-19b and mature miR-19b levels. Conversely, c-Jun overexpression enhanced H/R-induced pri-miR-19b. Studies using a luciferase reporter assay revealed that in cells transfected with vectors containing the wild-type miR-19b promoter and luciferase reporter, c-Jun overexpression or hypoxia/ reoxygenation significantly increased luciferase activity. c-Jun knockdown reduced the luciferase activity in these cells, suggesting that the miR-19b promoter is directly activated by c-Jun. Further, chromatin immunoprecipitation assay confirmed that c-Jun directly bound to the promoter DNA of miR-19b and hypoxia/reoxygenation significantly increased this interaction. Additionally, c-Jun silencing prevented cell surface syndecan-1 loss and endothelial barrier dysfunction in HLMECs after hypoxia/reoxygenation. Lastly, c-Jun was significantly elevated in patients with hemorrhagic shock compared to healthy controls.

CONCLUSION

Transcription factor c-Jun is inducible by hypoxia/reoxygenation, binds to and activates the miR-19b promoter. Using an in-vitro model of hemorrhagic shock, our findings identified a novel cellular mechanism whereby hypoxia/ reoxygenation increases miR-19b transcription by inducing c-Jun and leads to syndecan-1 decrease and endothelial cell barrier dysfunction. This finding supports that miR-19b could be a potential therapeutic target for hemorrhage shock.

Molecular mechanisms for ABCA1-mediated cholesterol efflux

The maintenance of cellular cholesterol homeostasis is essential for normal cell function and viability. Excessive cholesterol accumulation is detrimental to cells and serves as the molecular basis of many diseases, such as atherosclerosis, Alzheimer's disease, and diabetes mellitus. The peripheral cells do not have the ability to degrade cholesterol. Cholesterol efflux is therefore the only pathway to eliminate excessive cholesterol from these cells. This process is predominantly mediated by ATP-binding cassette transporter A1 (ABCA1), an integral membrane protein. ABCA1 is known to transfer intracellular free cholesterol and phospholipids to apolipoprotein A-I (apoA-I) for generating nascent high-density lipoprotein (nHDL) particles. nHDL can accept more free cholesterol from peripheral cells. Free cholesterol is then converted to cholesteryl ester by lecithin:cholesterol acyltransferase to form mature HDL. HDL-bound cholesterol enters the liver for biliary secretion and fecal excretion. Although how cholesterol is transported by ABCA1 to apoA-I remains incompletely understood, nine models have been proposed to explain this effect. In this review, we focus on the current view of the mechanisms underlying ABCA1-mediated cholesterol efflux to provide an important framework for future investigation and lipid-lowering therapy.

Key regulatory miRNAs in lipid homeostasis: implications for cardiometabolic diseases and development of novel therapeutics

Dysregulation of lipid metabolism is associated with cardiovascular/metabolic diseases, including atherosclerosis, liver diseases and type 2 diabetes mellitus (T2DM). Several miRNAs have been reported as regulators of different stages of lipid homeostasis, including cholesterol/fatty acid biosynthesis, degradation, transport, storage, and low-density (LDL) and high-density lipoprotein (HDL) formation. Indeed, various miRNAs are emerging as attractive therapeutic candidates for metabolic/cardiovascular disease (CVD). Here, we summarize the roles of miR-19b, miR-20a, miR-21, miR-27, miR-29, miR-34a, miR-144, miR-148a, and miR-199a in post-transcriptional regulation of genes involved in lipid metabolism and their therapeutic potential. We also discuss experimental strategies for further development of these miRNAs as novel cardiometabolic therapeutics. Teaser: miRNAs have emerged as crucial regulators of lipid homeostasis. Here, we highlight key miRNAs that regulate lipid metabolism and their therapeutic potential in cardiometabolic disease states.

Role of non-coding RNAs on liver metabolism and NAFLD pathogenesis

Obesity and type 2 diabetes are major contributors to the growing prevalence of non-alcoholic fatty liver disease (NAFLD), a chronic liver condition characterized by accumulation of fat in individuals without a significant amount of alcohol intake. The NAFLD spectrum ranges from simple steatosis (early stages, known as NAFL), to non-alcoholic steatohepatitis (NASH), which can progress to fibrosis and cirrhosis or hepatocellular carcinoma. Obesity, type 2 diabetes, and NAFLD are strongly associated with insulin resistance. In the liver, insulin resistance increases hepatic glucose output, lipogenesis, and VLDL secretion, leading to a combination of hyperglycemia and hypertriglyceridemia. Aberrant gene expression is a hallmark of insulin resistance. Non-coding RNAs (ncRNAs) have emerged as prominent regulators of gene expression that operate at the transcriptional, post-transcriptional, and post-translational levels. In the last couple of decades a wealth of studies have provided evidence that most processes of liver metabolism are orchestrated by ncRNAs. This review focuses on the role of microRNAs, long non-coding RNAs and circular RNAs as coordinators of hepatic function, as well as the current understanding on how their dysregulation contributes to abnormal metabolism and pathophysiology in animal models of insulin resistance and NAFLD. Moreover, ncRNAs are emerging as useful biomarkers that may be able to discriminate between the different stages of NAFLD. The potential of ncRNAs as therapeutic drugs for NAFLD treatment and as biomarkers is discussed.

Regulatory Non-coding RNAs in Atherosclerosis

Regulatory RNAs like microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) control vascular and immune cells' phenotype and thus play a crucial role in atherosclerosis. Moreover, the mutual interactions between miRNAs and lncRNAs link both types of regulatory RNAs in a functional network that affects lesion formation. In this review, we deduce novel concepts of atherosclerosis from the analysis of the current data on regulatory RNAs' role in endothelial cells (ECs) and macrophages. In contrast to arterial ECs, which adopt a stable phenotype by adaptation to high shear stress, macrophages are highly plastic and quickly change their activation status. At predilection sites of atherosclerosis, such as arterial bifurcations, ECs are exposed to disturbed laminar flow, which generates a dysadaptive stress response mediated by miRNAs. Whereas the highly abundant miR-126-5p promotes regenerative proliferation of dysadapted ECs, miR-103-3p stimulates inflammatory activation and impairs endothelial regeneration by aberrant proliferation and micronuclei formation. In macrophages, miRNAs are essential in regulating energy and lipid metabolism, which affects inflammatory activation and foam cell formation.Moreover, lipopolysaccharide-induced miR-155 and miR-146 shape inflammatory macrophage activation through their oppositional effects on NF-kB. Most lncRNAs are not conserved between species, except a small group of very long lncRNAs, such as MALAT1, which blocks numerous miRNAs by providing non-functional binding sites. In summary, regulatory RNAs' roles are highly context-dependent, and therapeutic approaches that target specific functional interactions of miRNAs appear promising against cardiovascular diseases.

WITHDRAWN: Role of microRNA-19b-3p on osteoporosis after experimental spinal cord injury in rats

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Genomic Variants and Multilevel Regulation of ABCA1, ABCG1, and SCARB1 Expression in Atherogenesis

Atheroprotective properties of human plasma high-density lipoproteins (HDLs) are determined by their involvement in reverse cholesterol transport (RCT) from the macrophage to the liver. ABCA1, ABCG1, and SR-BI cholesterol transporters are involved in cholesterol efflux from macrophages to lipid-free ApoA-I and HDL as a first RCT step. Molecular determinants of RCT efficiency that may possess diagnostic and therapeutic meaning remain largely unknown. This review summarizes the progress in studying the genomic variants of ABCA1, ABCG1, and SCARB1, and the regulation of their function at transcriptional and post-transcriptional levels in atherosclerosis. Defects in the structure and function of ABCA1, ABCG1, and SR-BI are caused by changes in the gene sequence, such as single nucleotide polymorphism or various mutations. In the transcription initiation of transporter genes, in addition to transcription factors, long noncoding RNA (lncRNA), transcription activators, and repressors are also involved. Furthermore, transcription is substantially influenced by the methylation of gene promoter regions. Post-transcriptional regulation involves microRNAs and lncRNAs, including circular RNAs. The potential biomarkers and targets for atheroprotection, based on molecular mechanisms of expression regulation for three transporter genes, are also discussed in this review.

Infections as Novel Risk Factors of Atherosclerotic Cardiovascular Diseases: Pathophysiological Links and Therapeutic Implications

Atherosclerotic cardiovascular diseases (ASCVD) are the major cause of mortality worldwide. Despite the continuous progress in ASCVD therapy, the residual risk persists beyond the management of traditional risk factors. Several infections including Helicobacter pylori infection, periodontal disease, and viral infections are associated with the increased risk of ASCVD, both directly by damage to the heart muscle and vasculature, and indirectly by triggering a systemic proinflammatory state. Hence, beyond the optimal management of the traditional ASCVD risk factors, infections should be considered as an important non-classical risk factor to enable early diagnosis and appropriate treatment. Here, we summarized the currently available evidence regarding the role of inflammation in ASCVD and the association between the particular infections and pathogens (Helicobacter pylori, periodontal disease, pneumonia, Cytomegalovirus, Human immunodeficiency virus, Herpes simplex virus, and severe acute respiratory syndrome coronavirus 2) on the development and progression of ASCVD. We also speculated about the potential therapeutic implications of the anti-inflammatory and anti-infective drugs on ASCVD outcomes, including drugs routinely administered in patients with ASCVD (statins, P2Y12 receptor inhibitors, and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers) and novel strategies aiming at residual risk reduction (colchicine, anti-cytokine drugs, and methotrexate). Considering the emerging association between infections and ASCVD, it is crucial to determine the possible advantages of infection prevention and treatment in patients with ASCVD.

Therapies Targeted at Non-Coding RNAs in Prevention and Limitation of Myocardial Infarction and Subsequent Cardiac Remodeling-Current Experience and Perspectives

Myocardial infarction is one of the major causes of mortality worldwide and is a main cause of heart failure. This disease appears as a final point of atherosclerotic plaque progression, destabilization, and rupture. As a consequence of cardiomyocytes death during the infarction, the heart undergoes unfavorable cardiac remodeling, which results in its failure. Therefore, therapies aimed to limit the processes of atherosclerotic plaque progression, cardiac damage during the infarction, and subsequent remodeling are urgently warranted. A hopeful therapeutic option for the future medicine is targeting and regulating non-coding RNA (ncRNA), like microRNA, circular RNA (circRNA), or long non-coding RNA (lncRNA). In this review, the approaches targeted at ncRNAs participating in the aforementioned pathophysiological processes involved in myocardial infarction and their outcomes in preclinical studies have been concisely presented.

MicroRNAs and Circular RNAs in Lipoprotein Metabolism

PURPOSE OF REVIEW

Non-coding RNAs (ncRNAs) including microRNAs (miRNAs) and circular RNAs (circRNAs) are pivotal regulators of mRNA and protein expression that critically contribute to cardiovascular pathophysiology. Although little is known about the origin and function of such ncRNAs, they have been suggested as promising biomarkers with powerful therapeutic value in cardiovascular disease (CVD). In this review, we summarize the most recent findings on ncRNAs biology and their implication on cholesterol homeostasis and lipoprotein metabolism that highlight novel therapeutic avenues for treating dyslipidemia and atherosclerosis.

RECENT FINDINGS

Clinical and experimental studies have elucidated the underlying effects that specific miRNAs impose both directly and indirectly regulating circulating high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL) metabolism and cardiovascular risk. Some of these relevant miRNAs include miR-148a, miR-128-1, miR-483, miR-520d, miR-224, miR-30c, miR-122, miR-33, miR-144, and miR-34. circRNAs are known to participate in a variety of physiological and pathological processes due to their abundance in tissues and their stage-specific expression activation. Recent studies have proven that circRNAs may be considered targets of CVD as well. Some of these cirRNAs are circ-0092317, circ_0003546, circ_0028198, and cirFASN that have been suggested to be strongly involved in lipoprotein metabolism; however, their relevance in CVD is still unknown. MicroRNA and cirRNAs have been proposed as powerful therapeutic targets for treating cardiometabolic disorders including atherosclerosis. Here, we discuss the recent findings in the field of lipid and lipoprotein metabolism underscoring the novel mechanisms by which some of these ncRNAs influence lipoprotein metabolism and CVD.

An octimibate derivative, Oxa17, enhances cholesterol efflux and exerts anti-inflammatory and atheroprotective effects in experimental atherosclerosis

Atherosclerotic cardiovascular diseases (ASCVDs), associated with vascular inflammation and lipid dysregulation, are responsible for high morbidity and mortality rates globally. For ASCVD treatment, cholesterol efflux plays an atheroprotective role in ameliorating inflammation and lipid dysregulation. To develop a multidisciplinary agent for promoting cholesterol efflux, octimibate derivatives were screened and investigated for the expression of ATP-binding cassette transporter A1 (ABCA1). Western blotting and qPCR analysis were conducted to determine the molecular mechanism associated with ABCA1 expression in THP-1 macrophages; results revealed that Oxa17, an octimibate derivative, enhanced ABCA1 expression through liver X receptors alpha (LXRα) activation but not through the microRNA pathway. We also investigated the role of Oxa17 in high-fat diet (HFD)-fed mice used as an in vivo atherosclerosis-prone model. In ldlr^-/- mice, Oxa17 increased plasma high-density lipoprotein (HDL) and reduced plaque formation in the aorta. Plaque stability improved via reduction of macrophage accumulation and via narrowing of the necrotic core size under Oxa17 treatment. Our study demonstrates that Oxa17 is a novel and potential agent for ASCVD treatment with atheroprotective and anti-inflammatory properties.

Foam Cells as Therapeutic Targets in Atherosclerosis with a Focus on the Regulatory Roles of Non-Coding RNAs

Atherosclerosis is a major cause of human cardiovascular disease, which is the leading cause of mortality around the world. Various physiological and pathological processes are involved, including chronic inflammation, dysregulation of lipid metabolism, development of an environment characterized by oxidative stress and improper immune responses. Accordingly, the expansion of novel targets for the treatment of atherosclerosis is necessary. In this study, we focus on the role of foam cells in the development of atherosclerosis. The specific therapeutic goals associated with each stage in the formation of foam cells and the development of atherosclerosis will be considered. Processing and metabolism of cholesterol in the macrophage is one of the main steps in foam cell formation. Cholesterol processing involves lipid uptake, cholesterol esterification and cholesterol efflux, which ultimately leads to cholesterol equilibrium in the macrophage. Recently, many preclinical studies have appeared concerning the role of non-encoding RNAs in the formation of atherosclerotic lesions. Non-encoding RNAs, especially microRNAs, are considered regulators of lipid metabolism by affecting the expression of genes involved in the uptake (e.g., CD36 and LOX1) esterification (ACAT1) and efflux (ABCA1, ABCG1) of cholesterol. They are also able to regulate inflammatory pathways, produce cytokines and mediate foam cell apoptosis. We have reviewed important preclinical evidence of their therapeutic targeting in atherosclerosis, with a special focus on foam cell formation.

HDAC3 protects against atherosclerosis through inhibition of inflammation via the microRNA-19b/PPARγ/NF-κB axis

BACKGROUND AND AIMS

Atherosclerosis (AS) is one of the leading causes of cardiovascular diseases. Studies have revealed critical roles of microRNAs (miRNAs) in the progression of AS. This study was conducted to elucidate the role and mechanism by which miR-19b influences AS.

METHODS

Human umbilical vein endothelial cells (HUVECs) were treated with oxidized-low-density lipoprotein (ox-LDL), and an AS mouse model was generated with the help of ApoE^-/- mice using a high-fat diet regimen. The expression patterns of peroxisome proliferator-activated receptor γ (PPARγ), nuclear factor κB (NF-κB)/p65, miR-19b and histone deacetylase 3 (HDAC3) were then characterized by reverse transcription quantitative polymerase chain reaction and Western blot analysis. In addition, the relationship among PPARγ, NF-κB/p65, miR-19b and HDAC3 was evaluated by co-immunoprecipitation, chromatin immunoprecipitation and dual-luciferase reporter gene assays. Gain- and loss-of-function experiments were also performed to examine their functional significance on ox-LDL-induced inflammation in HUVECs. Enzyme-linked immunosorbent assay was applied to determine the expression patterns of inflammatory factors in AS mice.

RESULTS

PPARγ and HDAC3 were poorly expressed, while miR-19b and NF-κB/p65 were highly expressed in ox-LDL-induced HUVECs and arterial tissues of AS mice. PPARγ inhibited ox-LDL-induced inflammation in HUVECs by ubiquitination and degradation of NF-κB/p65. miR-19b, downregulated by HDAC3, targeted PPARγ and negatively-regulated its expression. Upregulated PPARγ or HDAC3 or downregulated miR-19b or NF-κB/p65 reduced TNF-α and IL-1β expression levels in ox-LDL-induced HUVECs and AS mice.

CONCLUSIONS

Collectively, the results show that HDAC3 upregulation prevents inflammation to inhibit AS by inactivating NF-κB/p65 via upregulation of miR-19b-mediated PPARγ, providing a basic therapeutic consideration for AS treatment.

Emerging roles of non-coding RNAs in the metabolic reprogramming of tumor-associated macrophages

Macrophages are the most common immune cells in the tumor microenvironment, and tumor-associated macrophages play an important role in cancer development. Metabolic reprogramming is important for the functional plasticity of macrophages. Studies investigating the relevance of non-coding RNAs (ncRNAs) in human cancer found that ncRNAs can regulate the metabolism of cancer cells and tumor-associated macrophages. NcRNAs include short ncRNAs, long ncRNAs (lncRNAs), and circular RNAs (circRNAs). The most common short ncRNAs are microRNAs, which regulate glucose, lipid, and amino acid metabolism in macrophages by acting on metabolism-related pathways and targeting metabolism-related enzymes and proteins, and are therefore involved in cancer progression. The role of lncRNAs and circRNAs in the metabolism of tumor-associated macrophages remains unclear. LncRNAs affect the glucose metabolism of macrophages, whereas their role in lipid and amino acid metabolism is not clear. CircRNAs regulate amino acid metabolism in macrophages. The roles of ncRNAs in energy metabolism and the underlying mechanisms need to be investigated further. Here, we summarize recent findings on the involvement of ncRNAs in metabolic reprogramming in tumor-associated macrophages, which affect the tumor microenvironment and play important roles in the development of cancer. Improving our understanding of the effects of ncRNAs on metabolic reprogramming of tumor-associated macrophages may facilitate the development of effective clinical therapies.

MicroRNA regulation of cholesterol metabolism

MicroRNAs are small noncoding RNAs that regulate gene expression at the posttranscriptional level. Since many microRNAs have multiple mRNA targets, they are uniquely positioned to regulate the expression of several molecules and pathways simultaneously. For example, the multiple stages of cholesterol metabolism are heavily influenced by microRNA activity. Understanding the scope of microRNAs that control this pathway is highly relevant to diseases of perturbed cholesterol metabolism, most notably cardiovascular disease (CVD). Atherosclerosis is a common cause of CVD that involves inflammation and the accumulation of cholesterol-laden cells in the arterial wall. However, several different cell types participate in atherosclerosis, and perturbations in cholesterol homeostasis may have unique effects on the specialized functions of these various cell types. Therefore, our review discusses the current knowledge of microRNA-mediated control of cholesterol homeostasis, followed by speculation as to how these microRNA-mRNA target interactions might have distinctive effects on different cell types that participate in atherosclerosis.

Grape seed proanthocyanidins suppressed macrophage foam cell formation by miRNA-9 via targeting ACAT1 in THP-1 cells

Abnormal lipid metabolism in macrophages leads to atherosclerosis (AS). Excessive LDL cholesterol uptake by macrophages in the aortic endothelium leads to formation of foam cells. Previous studies suggested that proanthocyanidins effectively suppress this process, while the in-depth mechanism has not been elucidated. In mononuclear THP-1 cells, we found that the oligomeric fraction of proanthocyanidins was more effective in suppressing foam cell formation and 25 μg ml-1 for 48 h were the optimum conditions. Under these model conditions, we investigated gene expression and for the first time reported expression of regulatory microRNA (miRNA). It was found that the proanthocyanidins restrained macrophage foaming mainly by lowering the expression levels of cholesterol influx-related receptors CD36 and SR-A, and promoting the expression of cholesterol efflux-related receptor ABCA1. Further, it was latest revealed that proanthocyanidins could notably inhibit the expression of ACAT1, a key gene for intracellular cholesterol esterification. Further investigation was performed on the expression of regulatory miRNAs (miR-134 for CD36, miR-134, miR-155 for SR-A, miR-155, let-7g for LOX-1, miR-9 for ACAT1, miR-27a, miR-19b, miR-10b and miR-33a for ABCA1). The relative expression of miR-9, a miRNA targeting ACAT1, was decreased after the treatment of proanthocyanidins. It was most likely that proanthocyanidins suppressed the expression of ACAT1 via up-regulating the expression of miR-9, thus lessening the intracellular lipid accumulation and eventually inhibiting macrophage foam cell formation. This assumption was further verified by use of miR-9 mimic and its inhibitor.

miR-19b targets pulmonary endothelial syndecan-1 following hemorrhagic shock

Hemorrhagic shock results in systemic injury to the endothelium contributing to post-shock morbidity and mortality. The mechanism involves syndecan-1, the backbone of the endothelial glycocalyx. We have shown in a rodent model that lung syndecan-1 mRNA is reduced following hemorrhage, whereas the molecular mechanism underlying the mRNA reduction is not clear. In this study, we present evidence that miR-19b targets syndecan-1 mRNA to downregulate its expression. Our results demonstrate that miR-19b was increased in hemorrhagic shock patients and in-vitro specifically bound to syndecan-1 mRNA and caused its degradation. Further, hypoxia/reoxygenation (H/R), our in vitro hemorrhage model, increased miR-19b expression in human lung microvascular endothelial cells, leading to a decrease in syndecan-1 mRNA and protein. H/R insult and miR-19b mimic overexpression comparably exaggerated permeability and enhanced endothelial barrier breakdown. The detrimental role of miR-19b in inducing endothelial dysfunction was confirmed in vivo. Lungs from mice undergoing hemorrhagic shock exhibited a significant increase in miR-19b and a concomitant decrease in syndecan-1 mRNA. Pretreatment with miR-19b oligo inhibitor significantly decreased lung injury, inflammation, and permeability and improved hemodynamics. These findings suggest that inhibition of miR-19b may be a putative therapeutic avenue for mitigating post shock pulmonary endothelial dysfunction in hemorrhage shock.

Brothers in Arms: ABCA1- and ABCG1-Mediated Cholesterol Efflux as Promising Targets in Cardiovascular Disease Treatment

Atherosclerosis is a leading cause of cardiovascular disease worldwide, and hypercholesterolemia is a major risk factor. Preventive treatments mainly focus on the effective reduction of low-density lipoprotein cholesterol, but their therapeutic value is limited by the inability to completely normalize atherosclerotic risk, probably due to the disease complexity and multifactorial pathogenesis. Consequently, high-density lipoprotein cholesterol gained much interest, as it appeared to be cardioprotective due to its major role in reverse cholesterol transport (RCT). RCT facilitates removal of cholesterol from peripheral tissues, including atherosclerotic plaques, and its subsequent hepatic clearance into bile. Therefore, RCT is expected to limit plaque formation and progression. Cellular cholesterol efflux is initiated and propagated by the ATP-binding cassette (ABC) transporters ABCA1 and ABCG1. Their expression and function are expected to be rate-limiting for cholesterol efflux, which makes them interesting targets to stimulate RCT and lower atherosclerotic risk. This systematic review discusses the molecular mechanisms relevant for RCT and ABCA1 and ABCG1 function, followed by a critical overview of potential pharmacological strategies with small molecules to enhance cellular cholesterol efflux and RCT. These strategies include regulation of ABCA1 and ABCG1 expression, degradation, and mRNA stability. Various small molecules have been demonstrated to increase RCT, but the underlying mechanisms are often not completely understood and are rather unspecific, potentially causing adverse effects. Better understanding of these mechanisms could enable the development of safer drugs to increase RCT and provide more insight into its relation with atherosclerotic risk. SIGNIFICANCE STATEMENT: Hypercholesterolemia is an important risk factor of atherosclerosis, which is a leading pathological mechanism underlying cardiovascular disease. Cholesterol is removed from atherosclerotic plaques and subsequently cleared by the liver into bile. This transport is mediated by high-density lipoprotein particles, to which cholesterol is transferred via ATP-binding cassette transporters ABCA1 and ABCG1. Small-molecule pharmacological strategies stimulating these transporters may provide promising options for cardiovascular disease treatment.

A Traditional Korean Diet Alters the Expression of Circulating MicroRNAs Linked to Diabetes Mellitus in a Pilot Trial

The traditional Korean diet (K-diet) is considered to be healthy and circulating microRNAs (miRs) have been proposed as useful markers or targets in diet therapy. We, therefore, investigated the metabolic influence of the K-diet by evaluating the expression of plasma and salivary miRs. Ten women aged 50 to 60 years were divided into either a K-diet or control diet (a Westernized Korean diet) group. Subjects were housed in a metabolic unit-like condition during the two-week dietary intervention. Blood and saliva samples were collected before and after the intervention, and changes in circulating miRs were screened by an miR array and validated by individual RT-qPCRs. In the K-diet group, eight plasma miRs were down-regulated by array (p < 0.05), out of which two miRs linked to diabetes mellitus, hsa-miR26a-5p and hsa-miR126-3p, were validated (p < 0.05). Among five down-regulated salivary miRs, hsa-miR-92-3p and hsa-miR-122a-5p were validated, which are associated with diabetes mellitus, acute coronary syndrome and non-alcoholic fatty liver disease. In the control diet group, validated were down-regulated plasma hsa-miR-25-3p and salivary hsa-miR-31-5p, which are associated with diabetes mellitus, adipogenesis and obesity. The K-diet may influence the metabolic conditions associated with diabetes mellitus, as evidenced by changes in circulating miRs, putative biomarkers for K-diet.

MicroRNA sequences modulating inflammation and lipid accumulation in macrophage “foam” cells: Implications for atherosclerosis

Accumulation of macrophage “foam” cells, laden with cholesterol and cholesteryl ester, within the intima of large arteries, is a hallmark of early “fatty streak” lesions which can progress to complex, multicellular atheromatous plaques, involving lipoproteins from the bloodstream and cells of the innate and adaptive immune response. Sterol accumulation triggers induction of genes encoding proteins mediating the atheroprotective cholesterol efflux pathway. Within the arterial intima, however, this mechanism is overwhelmed, leading to distinct changes in macrophage phenotype and inflammatory status. Over the last decade marked gains have been made in understanding of the epigenetic landscape which influence macrophage function, and in particular the importance of small non-coding micro-RNA (miRNA) sequences in this context. This review identifies some of the miRNA sequences which play a key role in regulating “foam” cell formation and atherogenesis, highlighting sequences involved in cholesterol accumulation, those influencing inflammation in sterol-loaded cells, and novel sequences and pathways which may offer new strategies to influence macrophage function within atherosclerotic lesions.

Small Things Matter: Relevance of MicroRNAs in Cardiovascular Disease

MicroRNAs (miRNAs) are short sequences of non-coding RNA that play an important role in the regulation of gene expression and thereby in many physiological and pathological processes. Furthermore, miRNAs are released in the extracellular space, for example in vesicles, and are detectable in various biological fluids, such as serum, plasma, and urine. Over the last years, it has been shown that miRNAs are crucial in the development of several cardiovascular diseases (CVDs). This review discusses the (patho)physiological implications of miRNAs in CVD, ranging from cardiovascular risk factors (i.e., hypertension, diabetes, dyslipidemia), to atherosclerosis, myocardial infarction, and cardiac remodeling. Moreover, the intriguing possibility of their use as disease-specific diagnostic and prognostic biomarkers for human CVDs will be discussed in detail. Finally, as several approaches have been developed to alter miRNA expression and function (i.e., mimics, antagomirs, and target-site blockers), we will highlight the miRNAs with the most promising therapeutic potential that may represent suitable candidates for therapeutic intervention in future translational studies and ultimately in clinical trials. All in all, this review gives a comprehensive overview of the most relevant miRNAs in CVD and discusses their potential use as biomarkers and even therapeutic targets.

Non-coding RNAs in cardiovascular cell biology and atherosclerosis

Atherosclerosis underlies the predominant number of cardiovascular diseases and remains a leading cause of morbidity and mortality worldwide. The development, progression and formation of clinically relevant atherosclerotic plaques involves the interaction of distinct and over-lapping mechanisms which dictate the roles and actions of multiple resident and recruited cell types including endothelial cells, vascular smooth muscle cells, and monocyte/macrophages. The discovery of non-coding RNAs (ncRNAs) including microRNAs, long non-coding RNAs, and circular RNAs, and their identification as key mechanistic regulators of mRNA and protein expression has piqued interest in their potential contribution to atherosclerosis. Accruing evidence has revealed ncRNAs regulate pivotal cellular and molecular processes during all stages of atherosclerosis including cell invasion, growth, and survival; cellular uptake and efflux of lipids, expression and release of pro- and anti-inflammatory intermediaries, and proteolytic balance. The expression profile of ncRNAs within atherosclerotic lesions and the circulation have been determined with the aim of identifying individual or clusters of ncRNAs which may be viable therapeutic targets alongside deployment as biomarkers of atherosclerotic plaque progression. Consequently, numerous in vivo studies have been convened to determine the effects of moderating the function or expression of select ncRNAs in well-characterized animal models of atherosclerosis. Together, clinicopathological findings and studies in animal models have elucidated the multifaceted and frequently divergent effects ncRNAs impose both directly and indirectly on the formation and progression of atherosclerosis. From these findings' potential novel therapeutic targets and strategies have been discovered which may pave the way for further translational studies and possibly taken forward for clinical application.

Role of microRNAs in Hemophilia and Thrombosis in Humans

MicroRNAs (miRNA) play an important role in gene expression at the posttranscriptional level by targeting the untranslated regions of messenger RNA (mRNAs). These small RNAs have been shown to control cellular physiological processes including cell differentiation and proliferation. Dysregulation of miRNAs have been associated with numerous diseases. In the past few years miRNAs have emerged as potential biopharmaceuticals and the first miRNA-based therapies have entered clinical trials. Our recent studies suggest that miRNAs may also play an important role in the pathology of genetic diseases that are currently considered to be solely due to mutations in the coding sequence. For instance, among hemophilia A patients there exist a small subset, with normal wildtype genes; i.e., lacking in mutations in the coding and non-coding regions of the F8 gene. Similarly, in many patients with missense mutations in the F8 gene, the genetic defect does not fully explain the severity of the disease. Dysregulation of miRNAs that target mRNAs encoding coagulation factors have been shown to disturb gene expression. Alterations in protein levels involved in the coagulation cascade mediated by miRNAs could lead to bleeding disorders or thrombosis. This review summarizes current knowledge on the role of miRNAs in hemophilia and thrombosis. Recognizing and understanding the functions of miRNAs by identifying their targets is important in identifying their roles in health and diseases. Successful basic research may result in the development and improvement of tools for diagnosis, risk evaluation or even new treatment strategies.

Adipose-derived mesenchymal stem cells-derived exosome-mediated microRNA-342-5p protects endothelial cells against atherosclerosis

Exosomes are reported to mediate several disease-related microRNAs (miRNAs) to affect the progression of diseases, including atherosclerosis. Here, we aimed to screen the atherosclerosis-associated miRNAs and preliminarily investigate the potential regulatory mechanism of atherosclerosis. First, the lesion model for human umbilical vein endothelial cells (HUVECs) was favorably constructed. Later, through RNA-sequencing and bioinformatics analyses, miR-342-5p was identified in lesion model for HUVECs. MiR-342-5p overexpression or knockdown evidently promoted or inhibited the apoptosis of HUVECs impaired by H₂O₂. Mechanistically, PPP1R12B was found to have great potential as a target of miR-342-5p in HUVECs impaired by H₂O₂, supported by RNA-sequencing and a series of bioinformatics analyses. Meanwhile, the effect of miR-342-5p on PPP1R12B expression in HUVECs’ lesion model was explored, revealing that miR-342-5p had an inhibitory role in PPP1R12B expression. Additionally, adipose-derived mesenchymal stem cells (ADSCs) in spindle-like shape and their derived exosomes with 30 to 150 nm diameter were characterized. Furthermore, results showed miR-342-5p was evidently decreased in the presence of ADSCs-derived exosomes. These findings indicated ADSCs-derived exosomes restrained the expression of miR-324-5p in lesion model. Collectively, this work demonstrates an atherosclerosis-associated miR-342-5p and reveals a preliminary possible mechanism in which miR-342-5p mediated by ADSCs-derived exosomes protects endothelial cells against atherosclerosis.

Diagnostic and theranostic microRNAs in the pathogenesis of atherosclerosis

MicroRNAs (miRNAs) are a group of small single strand and noncoding RNAs that regulate several physiological and molecular signalling pathways. Alterations of miRNA expression profiles may be involved with pathophysiological processes underlying the development of atherosclerosis and cardiovascular diseases, including changes in the functions of the endothelial cells and vascular smooth muscle cells, such as cell proliferation, migration and inflammation, which are involved in angiogenesis, macrophage function and foam cell formation. Thus, miRNAs can be considered to have a crucial role in the progression, modulation and regulation of every stage of atherosclerosis. Such potential biomarkers will enable us to predict therapeutic response and prognosis of cardiovascular diseases and adopt effective preclinical and clinical treatment strategies. In the present review article, the current data regarding the role of miRNAs in atherosclerosis were summarized and the potential miRNAs as prognostic, diagnostic and theranostic biomarkers in preclinical and clinical studies were further discussed. The highlights of this review are expected to present opportunities for future research of clinical therapeutic approaches in vascular diseases resulting from atherosclerosis with an emphasis on miRNAs.

Interplay between Exosomes and Autophagy in Cardiovascular Diseases: Novel Promising Target for Diagnostic and Therapeutic Application

Exosome, is identified as a nature nanocarrier and intercellular messenger that regulates cell to cell communication. Autophagy is critical in maintenance of protein homeostasis by degradation of damaged proteins and organelles. Autophagy and exosomes take pivotal roles in cellular homeostasis and cardiovascular disease. Currently, the coordinated mechanisms for exosomes and autophagy in the maintenance of cellular fitness are now garnering much attention. In the present review, we discussed the interplay of exosomes and autophagy in the context of physiology and pathology of the heart, which might provide novel insights for diagnostic and therapeutic application of cardiovascular diseases.

Potential microRNA-related targets in clearance pathways of amyloid-β: novel therapeutic approach for the treatment of Alzheimer's disease

Imbalance between amyloid-beta (Aβ) peptide synthesis and clearance results in Aβ deregulation. Failure to clear these peptides appears to cause the development of Alzheimer's disease (AD). In recent years, microRNAs have become established key regulators of biological processes that relate among others to the development and progression of neurodegenerative diseases, such as AD. This review article gives an overview on microRNAs that are involved in the Aβ cascade and discusses their inhibitory impact on their target mRNAs whose products participate in Aβ clearance. Understanding of the mechanism of microRNA in the associated signal pathways could identify novel therapeutic targets for the treatment of AD.

A functional polymorphism in the promoter of miR-17-92 cluster is associated with decreased risk of ischemic stroke

Background

The microRNA-17-92 (miR-17-92) cluster is one of the most extensively studied miRNA clusters. Abnormal expression of the cluster has been found to play important role in different kinds of human diseases, including ischemic stroke (IS). The aim of our study was to investigate the association between three polymorphisms (rs1491034, rs9301654 and rs982873) in the promoter of the miR-17-92 cluster and risk of IS.

Methods

Three hundred and ninety-eight patients with IS and 397 control subjects were included. The genotypes of the three polymorphisms were determined by Snapshot SNP genotyping assay. Relative expression of the cluster in peripheral blood mononuclear cells (PBMCs) of cases and controls were examined by quantitative real-time PCR.

Results

Significant association between rs9301654 polymorphism and risk of IS were observed basing on genotype, model and allele analyses (GA vs. AA: adjusted OR = 0.63, 95% CI: 0.41~0.97, P = 0.037; GG vs. AA: adjusted OR = 0.23, 95% CI: 0.07~0.78, P = 0.018; GA + GG vs. AA: adjusted OR = 0.57, 95% CI: 0.38~0.87, P = 0.009; GA + AA vs. GG: adjusted OR = 0.27, 95% CI: 0.08~0.89, P = 0.032; G vs. A: adjusted OR = 0.58, 95% CI: 0.40~0.83). Haplotype analysis showed that TGC and TGT haplotypes were associated with decreased risk of IS (OR = 0.59, 95% CI: 0.40~0.87, P = 0.007 for TGC haplotype; OR = 0.21, 95% CI: 0.06~0.75, P = 0.009 for TGT haplotype). Importantly, we found the expression of miR-17-5p was significant higher while miR-19a-3p was significant lower in patient with IS compared with the control group (P < 0.01), and patients with rs9301654GG or GA genotype displayed lower level of miR-19a-3p compared with the AA genotype (P < 0.01).

Conclusions

Our findings indicated that rs9301654 polymorphism in the promoter of miR-17-92 cluster may be associated with susceptibility of IS in the Chinese population. However, we found that rs9301654 polymorphism and its respective gene expression did not demonstrate consistent association with IS in the Chinese population. Further studies such as gene-gene interaction are warranted to reveal the role of miR-19a and its regulatory genes in the etiology of IS.

Tanshinone IIA Promotes Macrophage Cholesterol Efflux and Attenuates Atherosclerosis of apoE-/- Mice by Omentin-1/ABCA1 Pathway

BACKGROUND

Tanshinone IIA (Tan IIA) and Omentin-1 have a protective role in the cardiovascular system. However, if and how Tan IIA and Omentin-1 regulate cholesterol metabolism in macrophages has not been fully elucidated.

OBJECTIVE

To investigate the possible mechanisms of Tan IIA and Omentin-1 on preventing macrophage cholesterol accumulation and atherosclerosis development.

METHODS

The effect of Tan IIA on the protein and mRNA levels of Omentin-1 and ATP-binding cassette transporter A1 (ABCA1) in macrophages was examined by Western blot and qRT-PCR assay, respectively. Cholesterol efflux was assessed by liquid scintillation counting (LSC). Cellular lipid droplet was measured by Oil Red O staining, and intracellular lipid content was detected by high performance liquid chromatography (HPLC). In addition, the serum lipid profile of apoE-/- mice was measured by enzymatic method. The size of atherosclerotic lesion areas and content of lipids and collagen in the aortic of apoE-/- mice were examined by Sudan IV, Oil-red O, and Masson staining, respectively.

RESULTS

Tan IIA up-regulated expression of Omentin-1 and ABCA1 in THP-1 macrophages, promoting ABCA1-mediated cholesterol efflux and consequently decreasing cellular lipid content. Consistently, Tan IIA increased reverse cholesterol transport in apoE-/- mice. Plasma levels of high-density lipoprotein cholesterol (HDL-C), ABCA1 expression and atherosclerotic plaque collagen content were increased while plasma levels of low-density lipoprotein cholesterol (LDL-C) and atherosclerotic plaque sizes were reduced in Tan IIA-treated apoE-/- mice. These beneficial effects were, however, essentially blocked by knockdown of Omentin-1.

CONCLUSION

Our results revealed that Tan IIA promotes cholesterol efflux and ameliorates lipid accumulation in macrophages most likely via the Omentin-1/ABCA1 pathway, reducing the development of aortic atherosclerosis.

miR-19 family: A promising biomarker and therapeutic target in heart, vessels and neurons

The miR-19 family, including miR-19a, miR-19b-1 and miR-19b-2, arises from two different paralogous clusters miR-17-92 and miR-106a-363. Although it is identified as oncogenic miRNA, the miR-19 family has also been found to play important roles in regulating normal tissue development. The precise control of miR-19 family level is essential for keeping tissue homeostasis and normal development of organisms. Its dysregulation leads to dysplasia, disease and even cancer. Therefore, this review focuses on the roles of miR-19 family in the development and disease of heart, vessels and neurons to estimate the potential value of miR-19 family as diagnostic biomarker or therapeutic target of cardiac, neurological, and vascular diseases.

Role of cholesterol homeostasis and its efflux pathways in cancer progression

Tumor cells show high avidity for cholesterol in order to support their inherent nature to divide and proliferate. This results in the rewiring of cholesterol homeostatic pathways by influencing not only de novo synthesis but also uptake or efflux pathways of cholesterol. Recent findings have pointed towards the importance of cholesterol efflux in tumor pathogenesis. Cholesterol efflux is the first and foremost step in reverse cholesterol transport and any perturbation in this pathway may lead to the accumulation of intracellular cholesterol, thereby altering the cellular equilibrium. This review addresses the different mechanisms of cholesterol efflux from the cell and highlights their role and regulation in context to tumor development. There are four different routes by which cholesterol can be effluxed from the cell namely, 1) passive diffusion of cholesterol to mature HDL particles, 2) SR-B1 mediated facilitated diffusion, 3) Active efflux to apo A1 via ABCA1 and 4) ABCG1 mediated efflux to mature HDL. These molecular players facilitating cholesterol efflux are engaged in a complex interplay with different signaling pathways. Thus, an understanding of the efflux pathways, their regulation and cross-talk with signaling molecules may provide novel prognostic markers and therapeutic targets to combat the onset of carcinogenesis.

miR-33-5p knockdown attenuates abdominal aortic aneurysm progression via promoting target adenosine triphosphate-binding cassette transporter A1 expression and activating the PI3K/Akt signaling pathway

PURPOSE

The aim of this study was to investigate the role of miR-33-5p in abdominal aortic aneurysm progression, which regulated adenosine triphosphate-binding cassette transporter A1 (ABCA1)-mediated cholesterol efflux and lipid accumulation in THP-1 macrophage-derived foam cells through the PI3K/Akt pathway.

METHODS

Quantitative reverse transcription polymerase chain reaction was used to evaluate the expression level of miR-33-5p and ABCA1 mRNA in abdominal aortic aneurysm patient and normal person tissues. The relationship between miR-33-5p and ABCA1 was examined by dual luciferase report assay. High-performance liquid chromatography was used to evaluate the levels of cholesterol contents. Cholesterol efflux detection was performed by liquid scintillator. The expression of inflammatory cytokines was detected by quantitative reverse transcription polymerase chain reaction. Western blot was applied to determine the expression levels of ABCA1, PI3K (p-PI3K), and Akt (p-Akt).

RESULTS

The quantitative reverse transcription polymerase chain reaction analysis results revealed miR-33-5p overexpression in abdominal aortic aneurysm tissues, but the expression level of ABCA1 was lower in abdominal aortic aneurysm tissues than non-abdominal aortic aneurysm tissues. Subsequently, the dual luciferase report gene assay confirmed that ABCA1 was a target of miR-33-5p, and miR-33-5p-negative regulated ABCA1 expression. Moreover, the expression levels of p-PI3K, p-Akt, and ABCA1 were decreased in THP-1 cell transferred with ABCA1 siRNA, but knockdown of miR-33-5p had an opposite effect. Furthermore, knockdown of miR-33-5p decreased the expression of MMP-2, MMP-9, TNF-α, total cellular cholesterol, and promoted cholesterol efflux in THP-1-derived foam cells. Importantly, LY294002 (PI3K inhibitor) or si-ABCA1 completely inhibited the stimulatory effects of miR-33-5p inhibitor.

CONCLUSION

This study has found that knockdown of miR-33-5p induced ABCA1 expression and promoted inflammatory cytokines and cholesterol efflux likely via activating the PI3K/Akt signaling pathway.

A microRNA‑24‑to‑secretagogin regulatory pathway mediates cholesterol‑induced inhibition of insulin secretion

Hypercholesterolemia is a key factor leading to β‑cell dysfunction, but its underlying mechanisms remain unclear. Secretagogin (Scgn), a Ca2+ sensor protein that is expressed at high levels in the islets, has been shown to play a key role in regulating insulin secretion through effects on the soluble N‑ethylmaleimide‑sensitive factor attachment receptor protein complexes. However, further studies are required to determine whether Scgn plays a role in hypercholesterolemia‑associated β‑cell dysfunction. The present study investigated the involvement of a microRNA‑24 (miR‑24)‑to‑Scgn regulatory pathway in cholesterol‑induced β‑cell dysfunction. In the present study, MIN6 cells were treated with increasing concentrations of cholesterol and then, the cellular functions and changes in the miR‑24‑to‑Scgn signal pathway were observed. Excessive uptake of cholesterol in MIN6 cells increased the expression of miR‑24, resulting in a reduction in Sp1 expression by directly targeting its 3' untranslated region. As a transcriptional activator of Scgn, downregulation of Sp1 decreased Scgn levels and subsequently decreased the phosphorylation of focal adhesion kinase and paxillin, which is regulated by Scgn. Therefore, the focal adhesions in insulin granules were impaired and insulin exocytosis was reduced. The present study concluded that a miR‑24‑to‑Scgn pathway participates in the mechanism regulating cholesterol accumulation‑induced β‑cell dysfunction.

Sortilin promotes macrophage cholesterol accumulation and aortic atherosclerosis through lysosomal degradation of ATP-binding cassette transporter A1 protein

Sortilin is closely associated with hyperlipidemia and the risk of atherosclerosis (AS). The role of sortilin and the underlying mechanism in peripheral macrophage are not fully understood. In this study, we investigated the effect of macrophage sortilin on ATP-binding cassette transporter A1 (ABCA1) expression, ABCA1-mediated cholesterol efflux, and aortic AS. Macrophage sortilin expression was upregulated by oxidized low-density lipoproteins (ox-LDLs) in both concentration- and time-dependent manners. Its expression reached the peak level when cells were incubated with 50 μg/ml ox-LDL for 24 h. Overexpression of sortilin in macrophage reduced cholesterol efflux, leading to an increase in intracellular total cholesterol, free cholesterol, and cholesterol ester. Sortilin was found to bind with ABCA1 protein and suppress macrophage ABCA1 expression, resulting in a decrease in cholesterol efflux from macrophages. The inhibitory effect of sortilin in cholesterol efflux was partially reversed by treatment with chloroquine, a lysosomal inhibitor. On the contrary, the ABCA1 protein level and ABCA1-mediated cholesterol efflux is increased by sortilin short hairpin RNA transfection. The fecal and biliary cholesterol 3H-sterol from cholesterol-laden mouse peritoneal macrophage was reduced by sortilin overexpression through lentivirus vector (LV)-sortilin in low-density lipoprotein receptor knockout mice, which was prevented by co-treatment with chloroquine. Treatment with LV-sortilin reduced plasma high-density lipoprotein and increased plasma ox-LDL levels. Accordingly, aortic lipid deposition and plaque area were exacerbated, and ABCA1 expression was reduced in mice in response to infection with LV-sortilin alone. These effects of LV-sortilin were partially reversed by chloroquine. Sortilin enhances lysosomal degradation of ABCA1 protein and suppresses ABCA1-mediated cholesterol efflux from macrophages, leading to foam cell formation and AS development.

MicroRNA-181a-5p and microRNA-181a-3p cooperatively restrict vascular inflammation and atherosclerosis

MicroRNAs have emerged as important post-transcriptional regulators of gene expression and are involved in diverse diseases and cellular process. Decreased expression of miR-181a has been observed in the patients with coronary artery disease, but its function and mechanism in atherogenesis is not clear. This study was designed to determine the roles of miR-181a-5p, as well as its passenger strand, miR-181a-3p, in vascular inflammation and atherogenesis. We found that the levels of both miR-181a-5p and miR-181a-3p are decreased in the aorta plaque and plasma of apoE^−/− mice in response to hyperlipidemia and in the plasma of patients with coronary artery disease. Rescue of miR-181a-5p and miR-181a-3p significantly retards atherosclerotic plaque formation in apoE^−/− mice. MiR-181a-5p and miR-181a-3p have no effect on lipid metabolism but decrease proinflammatory gene expression and the infiltration of macrophage, leukocyte and T cell into the lesions. In addition, gain-of-function and loss-of-function experiments show that miR-181a-5p and miR-181a-3p inhibit adhesion molecule expression in HUVECs and monocytes-endothelial cell interaction. MiR-181a-5p and miR-181a-3p cooperatively receded endothelium inflammation compared with single miRNA strand. Mechanistically, miR-181a-5p and miR-181a-3p prevent endothelial cell activation through blockade of NF-κB signaling pathway by targeting TAB2 and NEMO, respectively. In conclusion, these findings suggest that miR-181a-5p and miR-181a-3p are both antiatherogenic miRNAs. MiR-181a-5p and miR-181a-3p mimetics retard atherosclerosis progression through blocking NF-κB activation and vascular inflammation by targeting TAB2 and NEMO, respectively. Therefore, restoration of miR-181a-5p and miR-181a-3p may represent a novel therapeutic approach to manage atherosclerosis.

Resistin up-regulates LPL expression through the PPARγ-dependent PI3K/AKT signaling pathway impacting lipid accumulation in RAW264.7 macrophages

Resistin is a cysteine-rich cytokine, which has been indicated as a mediator of insulin resistance and inflammation. Previous studies demonstrated that lipoprotein lipase (LPL) was an important enzyme that could mediate lipid accumulation in macrophages. Additionally, the intracellular molecules phosphatidylinositol 3-kinase (PI3K)/serine-threonine protein kinase (AKT)/peroxisome proliferator-activated receptor (PPARγ) were supposed to be involved in the lipid accumulation process in cells. However, it remains unclear whether resistin was correlated with the dysregulation of lipid metabolism in macrophages. The present study investigated that resistin could up-regulate the expression of LPL and increase the contents of intracellular triglyceride (TG) and total cholesterol (TC) in RAW264.7 macrophages. In addition, intracellular molecules PI3K, AKT and PPARγ were significantly up-regulated and activated in resitin-stimulated RAW264.7 macrophages (P < 0.05). In contrast, the effects of resistin on RAW264.7 macrophages could be abrogated by specific inhibitors for LPL (LPL-siRNA) and PI3K/AKT signaling pathway (LY294002). All together, this study demonstrated that resistin could up-regulate the expression of LPL and induce lipid accumulation in RAW264.7 macrophages. More importantly, the PPARγ-dependent PI3K/AKT signaling pathway was relevant to the lipid accumulation process in resistin-stimulated macrophages.

MiR‑30e and miR‑92a are related to atherosclerosis by targeting ABCA1

Atherosclerosis is a chronic disease characterized by the accumulation of lipids and fibrous elements in the large arteries, which is the principal cause of coronary artery disease. Dysregulated exosomal microRNA (miRNA) levels in serum have been identified in patients with various diseases, including CAD. In the present study, nine candidate miRNAs were detected in the plasma exosome from 42 patients with coronary atherosclerosis, and a higher expression of miR‑30e and miR‑92a was identified in patients. Following bioinformatics analysis and confirmation through immunoblotting, it was demonstrated that ATP binding cassette (ABC)A1 is a direct target of miR‑30e, and miR‑92a. Furthermore, a negative correlation was identified between plasma miR‑30e and ABCA1, or miR‑30e and cholesterol. Thus, the results of the present study suggest that the miR‑30e level in exosomes from serum may have the potential to be a novel diagnostic biomarker for coronary atherosclerosis.

Retracted Article: MicroRNA-135a alleviates lipid accumulation and inflammation of atherosclerosis through targeting lipoprotein lipase

MicroRNAs (miRNAs) have recently attracted increasing attention for their involvement in atherosclerosis (AS). The purpose of this study was to further explore the function and underlying mechanism of miR-135a in AS progression. The expression levels of miR-135a and lipoprotein lipase (LPL) mRNA were detected by qRT-PCR, and LPL protein expression was measured by western blotting. The levels of blood lipids and inflammatory cytokines, and LPL activity were assessed using corresponding Assay Kits, and an HPLC assay was used to determine the levels of free cholesterol (FC), total cholesterol (TC) and cholesterol ester (CE). A Dil-oxLDL binding assay was performed to evaluate the ability of cholesterol uptake. The direct interaction between miR-135a and LPL was confirmed by a dual-luciferase reporter assay and RNA immunoprecipitation assay. Our data indicated that miR-135a was downregulated in serum samples of AS patients and mice. Upregulation of miR-135a alleviated lipid metabolic disorders and inflammation in AS mice. Moreover, miR-135a negatively regulated lipid accumulation and inflammation in ox-LDL-treated THP-1 macrophages. Mechanistically, miR-135a directly targeted LPL and repressed LPL expression. LPL mediated the regulatory effect of miR-135a on lipid accumulation and inflammation in ox-LDL-treated THP-1 macrophages. In conclusion, our study indicated that miR-135a upregulation ameliorated lipid accumulation and inflammation at least partly by targeting LPL in THP-1 macrophages, highlighting miR-135a as a potential antiatherogenic agent.

MicroRNAs (miRNAs) have recently attracted increasing attention for their involvement in atherosclerosis (AS).

MicroRNA-17, MicroRNA-19b, MicroRNA-146a, MicroRNA-302d Expressions in Hepatoblastoma and Clinical Importance

Hepatoblastoma (HB) is the most common liver malignancy in children. The prognosis changes according to the histologic subtypes of HB. In the present study, we aimed to characterize the expression level of selected microRNAs (miRNAs) in HB as well as in histologic subtypes, and to consider the association with the prognosis. A total of 22 HB tumor samples, subtyped as fetal (n=16) and embryonal (n=6), and 10 nontumorous surrounding liver samples were evaluated in this study. Expressions of miR-17, miR-146a, miR-302d, and miR-19b were analyzed in 22 HB tumor samples and 10 nontumorous surrounding liver samples by quantitative real-time polymerase chain reaction. Lower miRNA-17 expression levels were obtained in tumor samples in comparison with nontumorous surrounding liver samples (P=0.028). Lower miRNA-17 expression was significant for predicting prognosis in HB patients (area under receiver-operator characteristic curve=0.875, P=0.044). A higher-level of miR-19b was found in embryonal samples (P=0.008). Overall and event-free survival was not found to correlate with miRNA expression levels (P>0.05). This research finds miRNA-17 and miRNA-19b expression levels can provide important data on diagnosis and prognosis in HB showing different clinical behaviors.

Cholesterol transport system: An integrated cholesterol transport model involved in atherosclerosis

Atherosclerosis, the pathological basis of most cardiovascular disease (CVD), is closely associated with cholesterol accumulation in the arterial intima. Excessive cholesterol is removed by the reverse cholesterol transport (RCT) pathway, representing a major antiatherogenic mechanism. In addition to the RCT, other pathways are required for maintaining the whole-body cholesterol homeostasis. Thus, we propose a working model of integrated cholesterol transport, termed the cholesterol transport system (CTS), to describe body cholesterol metabolism. The novel model not only involves the classical view of RCT but also contains other steps, such as cholesterol absorption in the small intestine, low-density lipoprotein uptake by the liver, and transintestinal cholesterol excretion. Extensive studies have shown that dysfunctional CTS is one of the major causes for hypercholesterolemia and atherosclerosis. Currently, several drugs are available to improve the CTS efficiently. There are also several therapeutic approaches that have entered into clinical trials and shown considerable promise for decreasing the risk of CVD. In recent years, a variety of novel findings reveal the molecular mechanisms for the CTS and its role in the development of atherosclerosis, thereby providing novel insights into the understanding of whole-body cholesterol transport and metabolism. In this review, we summarize the latest advances in this area with an emphasis on the therapeutic potential of targeting the CTS in CVD patients.