IRF-1 and miRNA126 modulate VCAM-1 expression in response to a high-fat meal

NSun2 Deficiency Protects Endothelium From Inflammation via mRNA Methylation of ICAM-1

RATIONALE

Vascular endothelial inflammation, including the expression of intercellular adhesion molecule 1 (ICAM-1), is a key event in vascular diseases. However, the mechanisms underlying the regulation of ICAM-1 are largely unknown.

OBJECTIVE

To investigate the mechanisms on the regulation of ICAM-1 by NOP2/Sun domain family, member 2 (NSun2)-mediated mRNA methylation and the impact of NSun2-ICAM-1 regulatory process in vascular inflammation and allograft arteriosclerosis.

METHODS AND RESULTS

By using in vitro, in cells, and in vivo methylation assays, we showed that the tRNA methyltransferase NSun2 methylated the ICAM-1 mRNA. Methylation by NSun2 promoted the translation of ICAM-1, thereby increasing the adhesion of leukocytes to endothelial cells. Tumor necrosis factor-α or homocysteine activated the methyltransferase activity of NSun2 by repressing the phosphorylation of NSun2 by Aurora-B. The levels of ICAM-1 induction and of leukocyte adhesion to vascular endothelium observed with homocysteine treatment in wild-type rats were markedly decreased in NSun2(-/-) rats. In a rat model of aortic allograft, the lack of donor NSun2 impaired the formation of allograft arteriosclerosis.

CONCLUSIONS

NSun2 upregulates the expression of ICAM-1 by methylating ICAM-1 mRNA. This regulatory process impacts on vascular inflammation and allograft arteriosclerosis.

MiRNA-323-5p Promotes U373 Cell Apoptosis by Reducing IGF-1R

BACKGROUND MicroRNA regulates mammalian cell growth in terms of its proliferation and apoptosis by controlling the expression of target genes. MiRNA-323-5p plays an important role in regulating cell growth and death within various types of cells. The function of miRNA-323-5p and its possible molecular mechanism in human cerebral glioma U373 cells remains to be further confirmed. The aim of this study was to investigate the regulation function of miRNA-323-5p in human glioma U373 cell growth, proliferation, and apoptosis. MATERIAL AND METHODS We used human cerebral glioma U373 cells as the cell model; utilized liposome technology (transfected by Lipofectamine2000) in human cerebral glioma U373 cells to over-express miRNA-323-5p (microRNA used as control group); and selected MTT assay and flow cytometry to detect cell growth, proliferation, and apoptosis. We used RT-PCR and Western blotting techniques to study the expression levels of target insulin-like growth factor 1 (IGF-1) receptor protein in U373 cells transfected with miRNA-323-5p. We used liposome transfection techniques in human cerebral glioma U373 cells to over-express or processed knockdown of IGF-1R by siRNA, and then transferred with miRNA-323-5p, thereby investigating the treated human cerebral glioma U373 cells apoptosis situations. RESULTS The over-expression of miRNA-323-5p inhibited the growth and proliferation of human cerebral glioma U373 cells and promoted its apoptosis. The over-expression of miRNA-323-5p also reduced the IGF-1R level. After processing the knockdown of IGF-1R and then transfection with miRNA-323-5p, U373 cells had enhanced apoptosis. The over-expression of IGF-1R inhibited the cells apoptosis induced by miRNA-323-5p. CONCLUSIONS MiRNA-323-5p inhibited human cerebral glioma U373 cell proliferation and promoted its apoptosis by reducing IGF-1R.

Osteoblast-derived WNT-induced secreted protein 1 increases VCAM-1 expression and enhances prostate cancer metastasis by down-regulating miR-126

Bone metastases of prostate cancer (PCa) may cause intractable pain. Wnt-induced secreted protein-1 (WISP-1) belongs to the CCN family (CTGF/CYR61/NOV) that plays a key role in bone formation. We found that osteoblast-conditioned medium (OBCM) stimulates migration and vascular cell adhesion molecule-1 (VCAM-1) expression in human PCa (PC3 and DU145) cells. Osteoblast transfection with WISP-1 shRNA reduced OBCM-mediated PCa migration and VCAM-1 expression. Stimulation of PCa with OBCM or WISP-1 elevated focal adhesion kinase (FAK) and p38 phosphorylation. Either FAK and p38 inhibitors or siRNA abolished osteoblast-derived WISP-1-induced migration and VCAM-1 expression. Osteoblast-derived WISP-1 inhibited miR-126 expression. Moreover, miR-216 mimic reversed the WISP-1-enhanced migration and VCAM-1 expression. This study suggests that osteoblast-derived WISP-1 promotes migration and VCAM-1 expression in human PCa cells by down-regulating miR-126 expression via αvβ1 integrin, FAK, and p38 signaling pathways. Thus, WISP-1 may be a new molecular therapeutic target in PCa bone metastasis.

Effects of short-term walnut consumption on human microvascular function and its relationship to plasma epoxide content

Improved vascular function after the incorporation of walnuts into controlled or high-fat diets has been reported; however, the mechanism(s) underlying this effect of walnuts is(are) poorly defined. The objective of the current study was to evaluate the acute and short-term effects of walnut intake on changes in microvascular function and the relationship of these effects to plasma epoxides, the cytochrome-P450-derived metabolites of fatty acids. Thirty-eight hypercholesterolemic postmenopausal women were randomized to 4 weeks of 5 g or 40 g of daily walnut intake. All outcomes were measured after an overnight fast and 4 h after walnut intake. Microvascular function, assessed as the reactive hyperemia index (RHI), was the primary outcome measure, with serum lipids and plasma epoxides as secondary measures. Compared to 5 g of daily walnut intake, consuming 40 g/d of walnuts for 4 weeks increased the RHI and Framingham RHI. Total cholesterol and low- and high-density cholesterol did not significantly change after walnut intake. The change in RHI after 4 weeks of walnut intake was associated with the change in the sum of plasma epoxides (r=0.65, P=.002) but not with the change in the sum of plasma hydroxyeicosatetraenoic acids. Of the individual plasma epoxides, arachidonic-acid-derived 14(15)-epoxyeicosatrienoic acid was most strongly associated with the change in microvascular function (r=0.72, P<.001). These data support the concept that the intake of walnut-derived fatty acids can favorably affect plasma epoxide production, resulting in improved microvascular function.

Aggravated restenosis and atherogenesis in ApoCIII transgenic mice but lack of protection in ApoCIII knockouts: the effect of authentic triglyceride-rich lipoproteins with and without ApoCIII

AIM

Previously, our group and others have demonstrated a causative relationship between severe hypertriglyceridaemia and atherogenesis in mice. Furthermore, clinical investigations have shown high levels of plasma Apolipoprotein C-III (ApoCIII) associated with hypertriglyceridaemia and even cardiovascular disease. However, it remains unclear whether ApoCIII affects restenosis in vivo, and whether such an effect is mediated by ApoCIII alone, or in combination with hypertriglyceridaemia. We sought to investigate ApoCIII in restenosis and clarify how smooth muscle cells (SMCs) respond to authentic triglyceride-rich lipoproteins (TRLs) with or without ApoCIII (TRLs ± ApoCIII).

METHODS AND RESULTS

ApoCIII transgenic (ApoCIIItg) and knockout (ApoCIII-/-) mice underwent endothelial denudation to model restenosis. Here, ApoCIIItg mice displayed severe hypertriglyceridaemia and increased neointimal formation compared with wild-type (WT) or ApoCIII-/- mice. Furthermore, increased proliferating cell nuclear antigen (PCNA)-positive cells, Mac-3, and vascular cell adhesion protein-1 (VCAM-1) expression, and 4-hydroxynonenal (4HNE) production were found in lesion sites. ApoCIIItg and ApoCIII-/- mice were then crossed to low-density lipoprotein receptor-deficient (Ldlr-/-) mice and fed an atherogenic diet. ApoCIIItg/Ldlr-/- mice had significantly increased atherosclerotic lesions. However, there was no statistical difference in restenosis between ApoCIII-/- and WT mice, and in atherosclerosis between ApoCIII/Ldlr double knockout and Ldlr-/- mice. SMCs were then incubated in vitro with authentic TRLs ± ApoCIII isolated from extreme hypertriglyceridaemia glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1-deficient (GPIHBP1-/-) mice crossed with ApoCIIItg or ApoCIII-/- mice. It was shown that TRLs + ApoCIII promoted SMC proliferation, VCAM-1 expression, and reactive oxygen species (ROS) production, and activated the Akt pathway. Scavenging ROS significantly reduced SMC activation caused by TRLs + ApoCIII.

CONCLUSIONS

Severe hypertriglyceridaemia resulting from ApoCIII overexpression promotes restenosis and atherosclerosis. Furthermore, we demonstrated that TRLs + ApoCIII promotes SMC proliferation.

Noncoding RNAs, cytokines, and inflammation-related diseases

Chronic inflammation is involved in the onset and development of many diseases, including obesity, atherosclerosis, type 2 diabetes, osteoarthritis, autoimmune and degenerative diseases, asthma, periodontitis, and cirrhosis. The inflammation process is mediated by chemokines, cytokines, and different inflammatory cells. Although the molecules and mechanisms that regulate this primary defense mechanism are not fully understood, recent findings offer a putative role of noncoding RNAs, especially microRNAs (miRNAs), in the progression and management of the inflammatory response. These noncoding RNAs are crucial for the stability and maintenance of gene expression patterns that characterize some cell types, tissues, and biologic responses. Several miRNAs, such as miR-126, miR-132, miR-146, miR-155, and miR-221, have emerged as important transcriptional regulators of some inflammation-related mediators. Additionally, little is known about the involvement of long noncoding RNAs, long intergenic noncoding RNAs, and circular RNAs in inflammation-mediated processes and the homeostatic imbalance associated with metabolic disorders. These noncoding RNAs are emerging as biomarkers with diagnosis value, in prognosis protocols, or in the personalized treatment of inflammation-related alterations. In this context, this review summarizes findings in the field, highlighting those noncoding RNAs that regulate inflammation, with emphasis on recognized mediators such as TNF-α, IL-1, IL-6, IL-18, intercellular adhesion molecule 1, VCAM-1, and plasminogen activator inhibitor 1. The down-regulation or antagonism of the noncoding RNAs and the administration of exogenous miRNAs could be, in the near future, a promising therapeutic strategy in the treatment of inflammation-related diseases.

Platelet miRNAs and cardiovascular diseases

Activated platelets play a critical role in the acute complications of atherosclerosis that cause life-threatening ischemic events at late stages of the disease. The miRNAs are a novel class of small, non-coding RNAs that play a significant role in both inflammatory and cardiovascular diseases. The miRNAs are known to be present in platelets and exert important regulatory functions. Here we systematically examine the genes that are regulated by platelet miRNAs (miRNA-223,miRNA-126,miRNA-21, miRNA-24 and miRNA-197) and the association with cardiovascular disease risks. Platelet-secreted miRNAs could be novel biomarkers associated with cardiovascular diseases.

Evidence for a common biological pathway linking three Parkinson's disease-causing genes: parkin, PINK1 and DJ-1

Parkinson's disease (PD) is characterised by the loss of dopaminergic neurons in the midbrain. Autosomal recessive, early-onset cases of PD are predominantly caused by mutations in the parkin, PINK1 and DJ-1 genes. Animal and cellular models have verified a direct link between parkin and PINK1, whereby PINK1 phosphorylates and activates parkin at the outer mitochondrial membrane, resulting in removal of dysfunctional mitochondria via mitophagy. Despite the overwhelming evidence for this interaction, few studies have been able to identify a link for DJ-1 with parkin or PINK1. The aim of this review is to summarise the functions of these three proteins, and to analyse the existing evidence for direct and indirect interactions between them. DJ-1 is able to rescue the phenotype of PINK1-knockout Drosophila models, but not of parkin-knockouts, suggesting that DJ-1 may act in a parallel pathway to that of the PINK1/parkin pathway. To further elucidate a commonality between these three proteins, bioinformatics analysis established that Miro (RHOT1) interacts with parkin and PINK1, and HSPA4 interacts with all three proteins. Furthermore, 30 transcription factors were found to be common amongst all three proteins, with many of them being involved in transcriptional regulation. Interestingly, expression of these proteins and their associated transcription factors are found to be significantly down-regulated in PD patients compared to healthy controls. In summary, this review provides insight into common pathways linking three PD-causing genes and highlights some key questions, the answers to which may provide critical insight into the disease process.

Genetics and causality of triglyceride-rich lipoproteins in atherosclerotic cardiovascular disease

Triglycerides represent 1 component of a heterogeneous pool of triglyceride-rich lipoproteins (TGRLs). The reliance on triglycerides or TGRLs as cardiovascular disease (CVD) risk biomarkers prompted investigations into therapies that lower plasma triglycerides as a means to reduce CVD events. Genetic studies identified TGRL components and pathways involved in their synthesis and metabolism. We advocate that only a subset of genetic mechanisms regulating TGRLs contribute to the risk of CVD events. This "omic" approach recently resulted in new targets for reducing CVD events.

MicroRNA expression in circulating microvesicles predicts cardiovascular events in patients with coronary artery disease

Background

Circulating microRNAs (miRNAs) are differentially regulated and selectively packaged in microvesicles (MVs). We evaluated whether circulating vascular and endothelial miRNAs in patients with stable coronary artery disease have prognostic value for the occurrence of cardiovascular (CV) events.

Methods and Results

Ten miRNAs involved in the regulation of vascular performance—miR‐126, miR‐222, miR‐let7d, miR‐21, miR‐20a, miR‐27a, miR‐92a, miR‐17, miR‐130, and miR‐199a—were quantified in plasma and circulating MVs by reverse transcription polymerase chain reaction in 181 patients with stable coronary artery disease. The median duration of follow‐up for major adverse CV event–free survival was 6.1 years (range: 6.0–6.4 years). Events occurred in 55 patients (31.3%). There was no significant association between CV events and plasma level of the selected miRNAs. In contrast, increased expression of miR‐126 and miR‐199a in circulating MVs was significantly associated with a lower major adverse CV event rate. In univariate analysis, above‐median levels of miR‐126 in circulating MVs were predictors of major adverse CV event–free survival (hazard ratio: 0.485 [95% CI: 0.278 to 0.846]; P=0.007) and percutaneous coronary interventions (hazard ratio: 0.458 [95% CI: 0.222 to 0.945]; P=0.03). Likewise, an increased level of miR‐199a in circulating MVs was associated with a reduced risk of major adverse CV events (hazard ratio: 0.518 [95% CI: 0.299 to 0.898]; P=0.01) and revascularization (hazard ratio: 0.439 [95% CI: 0.232 to 0.832]; P=0.01) in univariate analysis. miRNA expression analysis in plasma compartments revealed that miR‐126 and miR‐199a are present mainly in circulating MVs. MV‐sorting experiments showed that endothelial cells and platelets were found to be the major cell sources of MVs containing miR‐126 and miR‐199a, respectively.

Conclusion

MVs containing miR‐126 and miR‐199a but not freely circulating miRNA expression predict the occurrence of CV events in patients with stable coronary artery disease.

Noncoding RNAs in vascular inflammation and atherosclerosis: recent advances toward therapeutic applications

PURPOSE OF REVIEW

We here highlight recent studies that in vivo demonstrate an involvement of microRNAs in atherosclerotic lesion formation and provide important preclinical evidence of their therapeutic targeting in atherosclerosis, with a particular focus on endothelial cells and macrophages. We also briefly discuss the emerging role of long noncoding RNAs herein.

RECENT FINDINGS

Noncoding RNAs have received considerable attention as regulators of different cell types and functions that dictate the inflammatory response in atherosclerosis. In particular, microRNAs have emerged to control endothelial cell functions by acting as mechanosensors that are regulated by flow, determinants of inflammation in the context of cytokine exposure and hypercholesterolemia and guardians of endothelial homeostasis. In addition, microRNAs control macrophage-driven cytokine production and polarization, and regulate cholesterol metabolism and foam cell formation. By these (cell specific) effects, microRNAs contain or drive atherosclerotic lesion formation and progression in animal models of disease and can be harnessed for therapeutic targeting.

SUMMARY

Given their multifaceted and specific contribution to vascular inflammation and atherosclerosis, and proven amenability for successful modulation in preclinical murine models of atheroscleorosis and large animal studies, miRNAs appear as promising therapeutic targets for treating atherosclerosis.

Endothelial microRNAs and atherosclerosis

The vascular endothelium, a thin layer of endothelial cells (ECs) that line the inner surface of blood vessels, is a critical interface between blood and all tissues. EC activation, dysfunction, and vascular inflammation occur when the endothelium is exposed to various insults such as proinflammatory cytokines, oxidative stress, hypertension, hyperglycemia, aging, and shear stress. These insults lead to the pathogenesis of a range of disease states, including atherosclerosis. Several signaling pathways, especially nuclear factor κB mediated signaling, play crucial roles in these pathophysiological processes. Recently, microRNAs (miRNAs) have emerged as important regulators of EC function by fine-tuning gene expression. In this review, we discuss how miRNAs regulate EC function and vascular inflammation in response to a variety of pathophysiologic stimuli. An understanding of the role of miRNAs in EC activation and dysfunction may provide novel targets and therapeutic opportunities for controlling atherosclerosis and other chronic inflammatory disease states.

Mechanosensing at the vascular interface

Mammals are endowed with a complex set of mechanisms that sense mechanical forces imparted by blood flow to endothelial cells (ECs), smooth muscle cells, and circulating blood cells to elicit biochemical responses through a process referred to as mechanotransduction. These biochemical responses are critical for a host of other responses, including regulation of blood pressure, control of vascular permeability for maintaining adequate perfusion of tissues, and control of leukocyte recruitment during immunosurveillance and inflammation. This review focuses on the role of the endothelial surface proteoglycan/glycoprotein layer-the glycocalyx (GCX)-that lines all blood vessel walls and is an agent in mechanotransduction and the modulation of blood cell interactions with the EC surface. We first discuss the biochemical composition and ultrastructure of the GCX, highlighting recent developments that reveal gaps in our understanding of the relationship between composition and spatial organization. We then consider the roles of the GCX in mechanotransduction and in vascular permeability control and review the prominent interaction of plasma-borne sphingosine-1 phosphate (S1P), which has been shown to regulate both the composition of the GCX and the endothelial junctions. Finally, we consider the association of GCX degradation with inflammation and vascular disease and end with a final section on future research directions.

Postprandial lipaemia and vascular disease

PURPOSE OF REVIEW

In this review we discuss the postprandial pathophysiological mechanisms that promote vascular disease, the evidence for a role of postprandial lipaemia (PPL) in vascular disease and the effect of modifiable and nonmodifiable factors in PPL.

RECENT FINDINGS

PPL refers to the dynamic changes in serum lipids and lipoproteins (mainly in serum triglycerides) that occur after a fat load or a meal. Recent data indicate that postprandial or nonfasting triglyceride levels are better predictors of cardiovascular risk, suggesting that efficiency of postprandial handling of triglyceride-rich lipoproteins plays a role in the causation of vascular disease.

SUMMARY

The recent finding that postprandial serum triglyceride levels are even better than fasting serum triglyceride levels as predictors of vascular disease indicate that it is better to measure an index of triglyceride-rich lipoproteins (in most cases serum triglyceride levels) in the postprandial period than in the postabsorptive fasting state. Moreover, by the time the postabsorptive state is reached, some of these proatherogenic triglyceride-rich lipoprotein changes may be missed in the measurement.

Rapamycin antagonizes TNF induction of VCAM-1 on endothelial cells by inhibiting mTORC2

Rapamycin modulates the ability of the vascular endothelium to mediate inflammation by inhibiting mTORC2 and reducing TNF-induced VCAM-1 expression.

Recruitment of circulating leukocytes into inflamed tissues depends on adhesion molecules expressed by endothelial cells (ECs). Here we report that rapamycin pretreatment reduced the ability of TNF-treated ECs to capture T cells under conditions of venular flow. This functional change was caused by inhibition of TNF-induced expression of vascular cell adhesion molecule-1 (VCAM-1) and could be mimicked by knockdown of mammalian target of rapamycin (mTOR) or rictor, but not raptor, implicating mTORC2 as the target of rapamycin for this effect. Mechanistically, mTORC2 acts through Akt to repress Raf1-MEK1/2-ERK1/2 signaling, and inhibition of mTORC2 consequently results in hyperactivation of ERK1/2. Increased ERK1/2 activity antagonizes VCAM-1 expression by repressing TNF induction of the transcription factor IRF-1. Preventing activation of ERK1/2 reduced the ability of rapamycin to inhibit TNF-induced VCAM-1 expression. In vivo, rapamycin inhibited mTORC2 activity and potentiated activation of ERK1/2. These changes correlated with reduced endothelial expression of TNF-induced VCAM-1, which was restored via pharmacological inhibition of ERK1/2. Functionally, rapamycin reduced infiltration of leukocytes into renal glomeruli, an effect which was partially reversed by inhibition of ERK1/2. These data demonstrate a novel mechanism by which rapamycin modulates the ability of vascular endothelium to mediate inflammation and identifies endothelial mTORC2 as a potential therapeutic target.

PINK1 and its familial Parkinson's disease-associated mutation regulate brain vascular endothelial inflammation

Parkinson's disease (PD) is a debilitating disorder that affects movement. Inflammation-mediated endothelial dysfunction has been found to be involved in neurodegenerative diseases, including PD. More than 40 PTEN-induced putative kinase 1 (PINK1) mutations have been found in PD patients. The effects of PINK1 in vascular inflammation are as yet unknown. In this study, our findings revealed that PINK1 can be increased by the inflammatory cytokine tumor necrosis factor-α in primary human brain microvascular endothelial cells (HBMECs). We found that wild-type PINK1 prevents expression of the adhesion molecule vascular cell adhesion molecule-1 (VCAM-1), thus inhibiting the attachment of monocytes to brain endothelial cells. However, PINK1G309D, the loss-of-function mutation associated with early-onset familial PD, promotes expression of VCAM-1 and exacerbates attachment of monocytes to brain endothelial cells. Mechanism studies revealed that overexpression of wild-type PINK1 inhibits the VCAM-1 promoter by inhibiting the transcriptional activity of interferon regulatory factor 1 (IRF-1). However, PINK1G309D promotes the VCAM-1 promoter by increasing the transcriptional activity of IRF-1.

Circulating miR-30a, miR-126 and let-7b as biomarker for ischemic stroke in humans

Background

Recently, plasma miRNAs have been reported as biomarkers for various diseases. However, the knowledge on the association of plasma miRNAs with ischemic stroke is still lacking. In this study, we investigated whether plasma concentrations of miR-30a, miR-126 and let-7b may be biomarkers for ischemic stroke in humans.

Methods

One hundred ninety seven patients with ischemic stroke were recruited and their blood samples were collected at 24 h, 1 week, 4 weeks, 24 weeks and 48 weeks after symptoms onset, and fifty healthy volunteers were selected as control. Levels of miRNA were quantified by quantitative real-time PCR. Relative expression level of miRNA was calculated using 2^-ΔΔct method. The ability to distinguish the ischemic stroke group from control group was characterized by receiver operating characteristic (ROC) curve, and the area under ROC curve (AUC) was calculated.

Results

Circulating miR-30a and miR-126 levels were markedly down-regulated in all patients with ischemic stroke until 24 weeks. However, circulating let-7b was lower in patients with large-vessel atherosclerosis than healthy volunteers, whereas circulating let-7b had higher level in patients with other kinds of ischemic stroke until 24 weeks. Among all patients, circulating miRNAs levels returned to normal 48 weeks after symptom onset. Receiver operating characteristic (ROC) curve analysis showed that the areas under the curve (AUC) of plasma miR-30a were 0.91, 0.91, 0.92 and 0.93, the miR-126 were 0.92, 0.94, 0.93 and 0.92, and let-7b were 0.93, 0.92, 0.92 and 0.91 at 24 h, 1 w, 4 w and 24 w, respectively.

Conclusions

These data suggest that miR-30a, miR-126 and let-7b might be useful biomarkers for ischemic stroke in humans.

Regulation of SIRT1 by oxidative stress-responsive miRNAs and a systematic approach to identify its role in the endothelium

SIGNIFICANCE

Oxidative stress is a common denominator of various risk factors contributing to endothelial dysfunction and vascular diseases. Accumulated evidence suggests that sirtuin 1 (SIRT1) expression and/or activity is impaired by supraphysiological levels of oxidative stress, which in turn disrupts endothelial homeostasis.

RECENT ADVANCES

Several microRNAs (miRNAs) are induced by oxidative stress and termed as oxidative stress-responsive miRNAs. They may play a role linking the imbalanced redox state with dysregulated SIRT1.

CRITICAL ISSUES

This review summarizes recent findings on oxidative stress-responsive miRNAs and their involvement in SIRT1 regulation. Because of the unique characteristics of miRNAs, research in this new area requires an integrative approach that combines bioinformatics and experimental validation. Thus, a research strategy is discussed to identify the SIRT1-regulating miRNAs under oxidative stress and their functional outcomes in relation to endothelial dysfunction. Additionally, the miRNAs implicated in vascular diseases such as atherosclerosis and abdominal aortic aneurysms are discussed along with the translational potential and challenges of using miRNAs and its analogs as therapeutic agents.

FUTURE DIRECTIONS

Although at its infancy, research on oxidative stress-responsive miRNAs and their regulation of SIRT1 may provide new insights in understanding vascular disorders. Moreover, systematic approaches integrating in silico, in vitro, and in vivo observations can be useful tools in revealing the pathways modulating endothelial biology.

MicroRNA associated with dyslipidemia and coronary disease in humans

MicroRNAs are structural components of an epigenetic mechanism of posttranscriptional regulation of messenger RNA translation. Recently, there has been significant interest in the application of microRNA as a blood-based biomarker of underlying physiological conditions. Dyslipidemia is a complex, heterogeneous condition conferring substantially increased risk for cardiovascular disease. The purpose of this review is to describe the current body of knowledge on the role of microRNA regulation of lipoprotein metabolism in humans and to discuss relevant methodological and study design considerations. We highlight the potential roles for microRNA in gene-environment interactions.

Triglyceride-rich lipoprotein modulates endothelial vascular cell adhesion molecule (VCAM)-1 expression via differential regulation of endoplasmic reticulum stress

Circulating triglyceride-rich lipoproteins (TGRL) from hypertriglyceridemic subjects exacerbate endothelial inflammation and promote monocyte infiltration into the arterial wall. We have recently reported that TGRL isolated from human blood after a high-fat meal can elicit a pro- or anti-atherogenic state in human aortic endothelial cells (HAEC), defined as up- or down-regulation of VCAM-1 expression in response to tumor necrosis factor alpha (TNFα) stimulation, respectively. A direct correlation was found between subjects categorized at higher risk for cardiovascular disease based upon serum triglycerides and postprandial production of TGRL particles that increased VCAM-1-dependent monocyte adhesion to inflamed endothelium. To establish how TGRL metabolism is linked to VCAM-1 regulation, we examined endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) pathways. Regardless of its atherogenicity, the rate and extent of TGRL internalization and lipid droplet formation by HAEC were uniform. However, pro-atherogenic TGRL exacerbated ER membrane expansion and stress following TNFα stimulation, whereas anti-atherogenic TGRL ameliorated such effects. Inhibition of ER stress with a chemical chaperone 4-phenylbutyric acid decreased TNFα-induced VCAM-1 expression and abrogated TGRL's atherogenic effect. Activation of ER stress sensors PKR-like ER-regulated kinase (PERK) and inositol requiring protein 1α (IRE1α), and downstream effectors including eukaryotic initiation factor-2α (eIF2α), spliced X-box-binding protein 1 (sXBP1) and C/EBP homologous protein (CHOP), directly correlated with the atherogenic activity of an individual's TGRL. Modulation of ER stress sensors also correlated with changes in expression of interferon regulatory factor 1 (IRF-1), a transcription factor of Vcam-1 responsible for regulation of its expression. Moreover, knockdown studies using siRNA defined a causal relationship between the PERK/eIF2α/CHOP pathway and IRF-1-mediated VCAM-1 expression. We conclude that ER stress and the UPR contribute to the regulation of Vcam-1 transcription as a function of the atherogenic nature of TGRL.

Gene expression in the vascular wall of the aortic arch in spontaneously hypertensive hyperlipidemic model rats using DNA microarray analysis

AIMS

In recent years, there has been an increase in patients with arteriosclerosis and the risk of lifestyle-related diseases. However, the pathogenesis and medication of atherosclerosis have not been elucidated. We developed a rat model of lifestyle-related diseases by feeding a high-fat diet and 30% sucrose solution (HFDS) to spontaneously hypertensive hyperlipidemic rats (SHHR) and reported that this model is a useful model of early atherosclerosis. In order to elucidate the pathogenesis of early atherosclerosis, we searched for atherosclerosis-related genes by microarray analysis using the aortic arch rat model of lifestyle-related diseases.

MAIN METHODS

Four-month-old male Sprague-Dawley rats and SHHR were each divided into two normal diet (ND) groups and two HFDS groups. After a four-month treatment, the expression of mRNA in the aortic arch was detected using the oligo DNA microarray one-color method and quantified using real-time PCR.

KEY FINDINGS

In this study, we detected 39 genes in microarray analysis. Esm1, Retnlb Mkks, and Grem2 showed particularly marked changes in gene expression in the SHHR-HFDS group. Compared with the SD-ND group, the SHHR-HFDS group had an increase in Mkks gene expression of about 26-fold and an approximately 22-fold increase in the expression of Grem2. Similarly, the expression of Esm1 increased by about 12-fold and that of Retnlg by about 10-fold as shown by quantitative real-time PCR.

SIGNIFICANCE

This study suggested that these four genes might be important in early atherosclerosis development.

Shear stress modulates VCAM-1 expression in response to TNF-α and dietary lipids via interferon regulatory factor-1 in cultured endothelium

Dyslipidemia is a primary risk factor for cardiovascular disease, but the specific mechanisms that determine the localization of atherosclerotic plaques in arteries are not well defined. Triglyceride-rich lipoproteins (TGRL) isolated from human plasma after a high-fat meal modulate TNF-α-induced VCAM-1 expression in cultured human aortic endothelial cells (HAECs) via an interferon regulatory factor (IRF)-1-dependent transcriptional mechanism. We examined whether fluid shear stress acts as a mediator of IRF-1-dependent VCAM-1 expression in response to cytokine and dietary lipids. IRF-1 and VCAM-1 were examined by immunofluorescence in TNF-α-stimulated HAEC monolayers exposed to TGRL and a linear gradient of shear stress ranging from 0 to 16 dyn/cm(2) in a microfluidic device. Shear stress alone modulated TNF-α-induced VCAM-1 expression, eliciting a 150% increase at low shear stress (2 dyn/cm(2)) and a 70% decrease at high shear stress (12 dyn/cm(2)) relative to static. These differences correlated with a 60% increase in IRF-1 expression under low shear stress and a 40% decrease under high shear stress. The addition of TGRL along with cytokine activated a fourfold increase in VCAM-1 expression and a twofold increase in IRF-1 expression. The combined effect of shear stress and TGRL on the upregulation of membrane VCAM-1 was abolished by transfection of HAECs with IRF-1-specific small interfering RNA. In a healthy swine model, elevated levels of endothelial IRF-1 were also observed within atherosusceptible regions of the aorta by Western blot analysis and immunohistochemistry, implicating arterial hemodynamics in the regulation of IRF-1 expression. These data demonstrate direct roles for fluid shear stress and postprandial TGRL from human serum in the regulation of IRF-1 expression and downstream inflammatory responses in HAECs.