MicroRNA-29a regulates pro-inflammatory cytokine secretion and scavenger receptor expression by targeting LPL in oxLDL-stimulated dendritic cells

MicroRNA signatures in the pathogenesis and therapy of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a persistent inflammatory illness of the gastrointestinal tract (GIT) triggered by an inappropriate immune response to environmental stimuli in genetically predisposed persons. Unfortunately, IBD patients' quality of life is negatively impacted by the symptoms associated with the disease. The exact etiology of IBD pathogenesis is not fully understood, but the emerging research indicated that the microRNA (miRNA) plays an important role. miRNAs have been documented to possess a significant role in regulating pro- and anti-inflammatory pathways, in addition to their roles in several physiological processes, including cell growth, proliferation, and apoptosis. Variations in the miRNA profiles might be a helpful prognostic indicator and a valuable tool in the differential diagnosis of IBD. Most interestingly, these miRNAs have a promising therapeutic target in several pre-clinical animal studies and phase 2 clinical studies to alleviate inflammation and improve patient's quality of life. This comprehensive review discusses the current knowledge about the significant physiological role of different miRNAs in the health of the intestinal immune system and addresses the role of the most relevant differentially expressed miRNAs in IBD, identify their potential targets, and emphasize their diagnostic and therapeutic potential for future research.

Expression of miRNAs and proinflammatory cytokines in pregnant women with gestational diabetes mellitus

Altered microRNAs (miRNAs1) and cytokines expression levels are associated with several pregnancy-induced complications. We evaluated the profile of circulating miRNAs (miR-17, miR-29a and miR-181a) and proinflammatory cytokines (TNF-α, IL-1β, IL-6 and IL-17) in women with gestational diabetes mellitus (GDM2), as well as their potential use as GDM biomarkers. The case-control study included 65 pregnant women divided into 2 groups - GDM and control. Expression levels of miRNAs in plasma samples and cytokines mRNA isolated from peripheral blood buffy coat were analyzed by quantitative real-time PCR (qPCR3). Significant miR-29a downregulation was found in GDM compared to the control group, and was even more significant after adjustments for covariates. miR-17 and miR-181a expression levels did not differ between the examined groups. Expression levels of IL-1β were significantly higher in GDM group compared to controls, while TNF-α, IL-6 and IL-17 did not show significant changes in expression between the two groups. As jugded from the ROC curve analysis, miR-29a and IL-1β had a significant capacity to discriminate between CG and GDM. Additionally, a positive correlation was established between IL-1β and TNF-α in the GDM group. GDM appeared to be associated with altered levels of miR-29a and IL-1β making them markers of this condition.

MicroRNAs: Key modulators of inflammation-associated diseases

Inflammation is a multifaceted biological and pathophysiological response to injuries, infections, toxins, and inflammatory mechanisms that plays a central role in the progression of various diseases. MicroRNAs (miRNAs) are tiny, 19-25 nucleotides long, non-coding RNAs that regulate gene expression via post-transcriptional repression. In this review, we highlight the recent findings related to the significant roles of miRNAs in regulating various inflammatory cascades and immunological processes in the context of many lifestyle-related diseases such as diabetes, cardiovascular diseases, cancer, etc. We also converse on how miRNAs can have a dual impact on inflammatory responses, suggesting that regulation of their functions for therapeutic purposes may be disease-specific.

Dynamic Alterations to Hepatic MicroRNA-29a in Response to Long-Term High-Fat Diet and EtOH Feeding

MicroRNA-29a (miR-29a) is a well characterized fibro-inflammatory molecule and its aberrant expression is linked to a variety of pathological liver conditions. The long-term effects of a high-fat diet (HFD) in combination with different levels of EtOH consumption on miR-29a expression and liver pathobiology are unknown. Mice at 8 weeks of age were divided into five groups (calorie-matched diet plus water (CMD) as a control group, HFD plus water (HFD) as a liver disease group, HFD plus 2% EtOH (HFD + 2% E), HFD + 10% E, and HFD + 20% E as intervention groups) and fed for 4, 13, 26, or 39 weeks. At each time point, analyses were performed for liver weight/body weight (BW) ratio, AST/ALT ratio, as well as liver histology assessments, which included inflammation, estimated fat deposition, lipid area, and fibrosis. Hepatic miR-29a was measured and correlations with phenotypic traits were determined. Four-week feeding produced no differences between the groups on all collected phenotypic traits or miR-29a expression, while significant effects were observed after 13 weeks, with EtOH concentration-specific induction of miR-29a. A turning point for most of the collected traits was apparent at 26 weeks, and miR-29a was significantly down-regulated with increasing liver injury. Overall, miR-29a up-regulation was associated with a lower liver/BW ratio, fat deposition, inflammation, and fibrosis, suggesting a protective role of miR-29a against liver disease progression. A HFD plus increasing concentrations of EtOH produces progressive adverse effects on the liver, with no evidence of beneficial effects of low-dose EtOH consumption. Moreover, miR-29a up-regulation is associated with less severe liver injury.

Elevated miR-29c-5p Expression in Nipple Aspirate Fluid Is Associated with Extremely High Mammographic Breast Density

Simple Summary

High mammographic density is a known risk factor for breast cancer. However, the underlying mechanisms of high mammographic density development and breast cancer are unknown. MicroRNAs are potential biomarkers indicative of carcinogenesis and can be assessed in nipple aspirate fluid. We used nipple aspirate fluid from women with very low and extremely high mammographic density to examine differences in expression of multiple miRNAs between both extremes in the spectrum of mammographic density. We found that hsa-miR-29c-5p was upregulated in an extremely high mammographic density context and potential targets were identified that might provide clues of the relationship between high mammographic density and breast cancer risk. Understanding the relationship between high mammographic density and breast cancer is of great value for early breast cancer diagnosis and treatment. With our research we provide new insight into this relationship and further research could determine the effects of dysregulated hsa-miR-29c-5p on the identified candidate targets.

Abstract

High mammographic density (MD) is associated with an increased risk of breast cancer, however the underlying mechanisms are largely unknown. This research aimed to identify microRNAs (miRNAs) that play a role in the development of extremely dense breast tissue. In the discovery phase, 754 human mature miRNAs were profiled in 21 extremely high MD- and 20 very low MD-derived nipple aspirate fluid (NAF) samples from healthy women. In the validation phase, candidate miRNAs were assessed in a cohort of 89 extremely high MD and 81 very low MD NAF samples from healthy women. Independent predictors of either extremely high MD or miRNA expression were identified by logistic regression and linear regression analysis, respectively. mRNA targets and pathways were identified through miRTarBase, TargetScan, and PANTHER pathway analysis. Statistical analysis identified four differentially expressed miRNAs during the discovery phase. During the validation, linear regression (p = 0.029; fold change = 2.10) and logistic regression (p = 0.048; odds ratio = 1.38) showed that hsa-miR-29c-5p was upregulated in extremely high MD-derived NAF. Identified candidate mRNA targets of hsa-miR-29c-5p are CFLAR, DNMT3A, and PTEN. Further validation and exploration of targets and downstream pathways of has-miR-29c-5p will provide better insight into the processes involved in the development of high MD and in the associated increased risk of breast cancer.

Differentially Expressed miRNAs in Ulcerative Colitis and Crohn’s Disease

Differential microRNA (miRNA or miR) regulation is linked to the development and progress of many diseases, including inflammatory bowel disease (IBD). It is well-established that miRNAs are involved in the differentiation, maturation, and functional control of immune cells. miRNAs modulate inflammatory cascades and affect the extracellular matrix, tight junctions, cellular hemostasis, and microbiota. This review summarizes current knowledge of differentially expressed miRNAs in mucosal tissues and peripheral blood of patients with ulcerative colitis and Crohn’s disease. We combined comprehensive literature curation with computational meta-analysis of publicly available high-throughput datasets to obtain a consensus set of miRNAs consistently differentially expressed in mucosal tissues. We further describe the role of the most relevant differentially expressed miRNAs in IBD, extract their potential targets involved in IBD, and highlight their diagnostic and therapeutic potential for future investigations.

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.

An Update on the Role of Extracellular Vesicles in the Pathogenesis of Necrotizing Enterocolitis and Inflammatory Bowel Diseases

Some of the most fundamental influences of microorganisms inhabiting the human intestinal tract are exerted during infant development and impact the maturation of intestinal mucosa and gut immune system. The impact of bacteria on the host gut immune system is partially mediated via released extracellular vesicles (EVs). The heterogeneity in EV content, size, and bacterial species origin can have an impact on intestinal cells, resulting in inflammation and an immune response, or facilitate pathogen entry into the gut wall. In mammals, maintaining the integrity of the gut barrier might also be an evolutionary function of maternal milk EVs. Recently, the usage of EVs has been explored as a novel therapeutic approach in several pathological conditions, including necrotizing enterocolitis (NEC) and inflammatory bowel disease (IBD). In this review, we attempt to summarize the current knowledge of EV biology, followed by a discussion of the role that EVs play in gut maturation and the pathogenesis of NEC and IBD.

Loss of miR-29a/b1 promotes inflammation and fibrosis in acute pancreatitis

MicroRNA-29 (miR-29) is a critical regulator of fibroinflammatory processes in human diseases. In this study, we found a decrease in miR-29a in experimental and human chronic pancreatitis, leading us to investigate the regulatory role of the miR-29a/b1 cluster in acute pancreatitis (AP) utilizing a conditional miR-29a/b1-KO mouse model. miR-29a/b1-sufficient (WT) and -deficient (KO) mice were administered supramaximal caerulein to induce AP and characterized at different time points, utilizing an array of IHC and biochemical analyses for AP parameters. In caerulein-induced WT mice, miR-29a remained dramatically downregulated at injury. Despite high-inflammatory milieu, fibrosis, and parenchymal disarray in the WT mice during early AP, the pancreata fully restored during recovery. miR-29a/b1-KO mice showed significantly greater inflammation, lymphocyte infiltration, macrophage polarization, and ECM deposition, continuing until late recovery with persistent parenchymal disorganization. The increased pancreatic fibrosis was accompanied by enhanced TGFβ1 coupled with persistent αSMA+ PSC activation. Additionally, these mice exhibited higher circulating IL-6 and inflammation in lung parenchyma. Together, this collection of studies indicates that depletion of miR-29a/b1 cluster impacts the fibroinflammatory mechanisms of AP, resulting in (a) aggravated pathogenesis and (b) delayed recovery from the disease, suggesting a protective role of the molecule against AP.

MALAT1 overexpression attenuates AS by inhibiting ox-LDL-stimulated dendritic cell maturation via miR-155-5p/NFIA axis

MALAT1 is associated with dendritic cells (DCs) maturation in Atherosclerosis (AS). This article aims to demystify the role of MALAT1 in AS. We separated immature DCs (iDCs) from healthy volunteers or ApoE-/- mice. And iDCs were treated with oxidized low density lipoprotein (ox-LDL) to induce DCs maturation. We found that ox-LDL promoted the levels of DCs maturation markers including CD83, CD86, IL-12 and IL-6. MALAT1 and NFIA were down-regulated, whereas miR-155-5p was up-regulated in the ox-LDL-treated iDCs. Furthermore, DCs maturation was notably suppressed by MALAT1 overexpression, NFIA overexpression or miR-155-5p knockdown. Moreover, MALAT1 functioned as a competing endogenous RNA to repress miR-155-5p, which controlled its down-stream target, NFIA. In addition, MALAT1 overexpression inhibited ox-LDL-stimulated DCs maturation by regulating miR-155-5p/NFIA axis. In AS mice, MALAT1 overexpression attenuated ox-LDL-stimulated DCs maturation and reduced atherosclerotic plaque area. In summary, our study demonstrates that MALAT1 overexpression attenuates AS by inhibiting ox-LDL-stimulated DCs maturation via miR-155-5p/NFIA axis. Thus, MALAT1/miR-155-5p/NFIA axis can potentially be used in the treatment of AS.

Exploration of the Molecular Mechanism for Lipoprotein Lipase Expression Variations in SH-SY5Y Cells Exposed to Different Doses of Amyloid-Beta Protein

Progressive accumulation of amyloid-β (Aβ) plaques in the brain is a characteristic pathological change in Alzheimer's disease (AD). We previously found the expression of lipoprotein lipase (LPL) was increased in SH-SY5Y cells exposed to low-dose Aβ and decreased in cells with high-dose Aβ exposure, but the molecular mechanism is still unclear. Based on previous studies, the opposite regulation of histone deacetylase2 (HDAC2) and HDAC3 on LPL expression probably explain the above molecular mechanism, in which microRNA-29a and peroxisome proliferator-activated receptor γ (PPARγ) may be involved. This study further revealed the mechanism of HDAC2 and HDAC3 on conversely regulating LPL expression. The results showed that HDAC2 down-regulated microRNA-29a by decreasing histone acetylation (Ace-H3K9) level in its promoter region, subsequently increasing LPL expression directly or through PPARγ/LPL pathway; HDAC3 decreased LPL expression through inhibiting Ace-H3K9 levels in LPL and PPARγ promoter regions and up-regulating microRNA-29a. This study also found that with increasing concentrations of Aβ in cells, HDAC2 and HDAC3 expression were gradually increased, and Ace-H3K9 levels in LPL and PPARγ promoter region regulated by HDAC3 were decreased correspondingly, while Ace-H3K9 levels in microRNA-29a promoter region modulated by HDAC2 were not decreased gradually but presented a U-shaped trend. These may lead to the results that a U-shaped alteration in microRNA-29a expression, subsequently leading to an inverse U-shaped alteration in PPARγ or LPL expression. In conclusion, HDAC2 and HDAC3 at least partly mediate LPL expression variations in different concentrations of Aβ exposed SH-SY5Y cells, in which microRNA-29a and PPARγ are involved, and the histone acetylation level in microRNA-29a promoter region plays a key role.

Role of microRNAs in the Regulation of Dendritic Cell Generation and Function

Dendritic cells (DCs) are antigen-presenting cells with a key role in immune responses. They act as a link between the innate and adaptive systems and they can induce and maintain immunologic tolerance. DCs are subdivided into conventional and plasmacytoid DCs. These cell subsets originate from the same bone marrow precursors and their differentiation process is determined by several extrinsic and intrinsic factors, such as cytokines, transcription factors, and miRNAs. miRNAs are small non-coding RNAs that play a crucial role in modulating physiological and pathological processes mediated by DCs. miRNA deregulation affects many inflammatory conditions and diseases. The aim of this review was to underline the importance of miRNAs in inflammatory processes mediated by DCs in physiological and pathological conditions and to highlight their potential application for future therapies.

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.

Wnt5a/Ror2 pathway contributes to the regulation of cholesterol homeostasis and inflammatory response in atherosclerosis

Atherosclerosis (AS) is characterized by lipids metabolism disorder and inflammatory response. Accumulating evidence has demonstrated that Wingless type 5a (Wnt5a) is implicated in cardiovascular diseases through non-canonical Wnt cascades. However, its precise role during the pathogenesis of AS is still unclear. Therefore, the present study aims to investigate the role and the underlying mechanism of Wnt5a/receptor tyrosine kinase-like orphan receptor 2 (Ror2) pathways in the promotion of AS process through affecting lipid accumulation and inflammation. In atherosclerotic clinical samples, Wnt5a levels were measured by using enzyme-linked immunosorbent assay (ELISA) assay. In vivo experiments were conducted by using apolipoprotein E knockout (apoE^-/-) mice model. Vascular smooth muscle cells (VSMCs) were applied for in vitro studies. Wnt5a was highly expressed in both of atherosclerotic clinical samples and apoE^-/- mice. The knockdown of Wnt5a significantly inhibited cholesterol accumulation and inflammatory response. Additionally, the lipopolysaccharide (LPS)-induced inflammation aggravated the cholesterol accumulation and decreased adenosine triphosphate (ATP)-binding cassette transporter A1 (ABCA1) expression in VSMCs. Depletion of intracellular cholesterol by β-cyclodextrin (β-CD) led to the upregulation of ABCA1 and the inhibition of inflammation. Conversely, the overexpression of Wnt5a inhibited ABCA1 expression, facilitated cholesterol accumulation, impared cholesterol efflux, promoted NF-κB nuclear translocation and the inflammatory cytokines secretion. Moreover, the knockdown of Ror2 increased ABCA1 expression and reduced Wnt5a-induced cholesterol accumulation and inflammatory responses. Furthermore, the knockdown of ABCA1 enhanced cholesterol accumulation and inflammatory response. Therefore, Wnt5a/Ror2 pathway was critical in regulating cholesterol homeostasis and inflammatory response, which might be a promising therapeutic target for AS therapy.

CD 36: Focus on Epigenetic and Post-Transcriptional Regulation

CD36 is a transmembrane protein involved in fatty acid translocation, scavenging for oxidized fatty acids acting as a receptor for adhesion molecules. It is expressed on macrophages, as well as other types of cells, such as endothelial and adipose cells. CD36 participates in muscle lipid uptake, adipose energy storage, and gut fat absorption. Recently, several preclinical and clinical studies demonstrated that upregulation of CD36 is a prerequisite for tumor metastasis. Cancer metastasis-related research emerged much later and has been less investigated, though it is equally or even more important. CD36 protein expression can be modified by epigenetic changes and post-transcriptional interference from non-coding RNAs. Some data indicate modulation of CD36 expression in specific cell types by epigenetic changes via DNA methylation patterns or histone tails, or through miRNA interference, but this is largely unexplored. The few papers addressing this topic refer mostly to lipid metabolism-related pathologies, whereas in cancer research, data are even more scarce. The aim of this review was to summarize major epigenetic and post-transcriptional mechanisms that impact CD36 expression in relation to various pathologies while highlighting the areas in need of further exploration.

Immune-regulatory microRNA expression levels within circulating extracellular vesicles correspond with the appearance of local symptoms after seasonal flu vaccination

Extracellular vesicles (EVs) contain microRNAs (miRNAs) that regulate the innate immune responses, such as the production of pro-inflammatory cytokines. The excessive production of pro-inflammatory cytokines after vaccination can cause local adverse reactions, such as pain, itching, swelling, and redness. Previous studies have shown that circulating EV miR-451a regulates innate immune responses, and miR-451a levels in serum EVs are negatively correlated with the pro-inflammatory cytokine expression levels in response to the influenza vaccine. Since excessive pro-inflammatory cytokine production is a cause of the local adverse reactions to vaccination, we investigated whether miR-451a levels in serum EVs correlate with local symptoms at the vaccination site, such as pain, itching, swelling, and redness. Interestingly, miR-451a levels in serum EVs were inversely correlated with the number of symptoms after vaccination. We determined the level of several other immune-regulatory miRNAs in serum EVs. Using the immune-regulatory miRNA levels of miR-22, miR-29a, miR-451a, and miR-107, we calculated a normalized miRNA level for each healthy donor and found that the normalized miRNA levels were significantly correlated with the number of local symptoms after vaccination. Our data indicated that immune-regulatory miRNA levels in serum EVs can be used as biomarkers to assess local symptoms after influenza vaccination.

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).

MiR-29a inhibited intestinal epithelial cells autophagy partly by decreasing ATG9A in ulcerative colitis

Ulcerative colitis (UC), with high morbidity has become one of the fastest-growing severe illnesses in the world. Although MiR-29a is highly expressed in the tissues of UC patients, the mechanism of miR-29a involved in the specific pathogenesis of UC is not known. In this study, a GFP-light chain 3 (LC3) immunofluorescence assay was used to observe the formation of the autophagic spot; qRT-PCR and western blotting analyses were carried out to detect the expression of autophagy-related proteins, including BECN1, Autophagy-related gene (ATG)5, ATG16L, and transcription factor EB. The dual-fluorescence reporter assay was used to analyze the direct effect of miR-29a on ATG9A; experimental dextran sulfate sodium-induced colitis in mice was used to establish the UC model. Our studies showed that the overexpression of miR-29a not only suppressed the production of GFP-LC3 autophagy spots but also inhibited the level of LC3II/LC3I and upregulated the expression of P62 in HT29 and HCT116 cells. Moreover, the results showed that miR-29a directly targeted the 3'UTR region of ATG9A mRNA to suppress the activation of HT29 and HCT116 cells' autophagy. Also, overexpression of ATG9A rescued rapamycin-induced autophagy that was inhibited by overexpression of miR-29a. In addition, miR-29a also affected the expression of autophagy-related proteins (BECN1, ATG5, ATG16L1, and transcription factor EB). Notably, miR-29a was upregulated, whereas ATG9A was downregulated in the experimental dextran sulfate sodium-induced colitis in mice. In effect, this study showed that miR-29a inhibits rapamycin-induced intestinal epithelial cells' autophagy partly by decreasing ATG9A in UC. These findings may provide new insights that may help control the inflammation in UC.

Tenascin‑C promotes the migration of bone marrow stem cells via toll‑like receptor 4‑mediated signaling pathways: MAPK, AKT and Wnt

There are currently limitations in stem cell therapy due to the low rate of homing and proliferation of cells following transplantation. The present study was designed to investigate the effects of Tenascin-C (TN-C) on bone marrow mesenchymal stem cells (BMSCs) and its underlying mechanisms. BMSCs were obtained from C57BL/6 mice. The survival and proliferation of BMSCs was analyzed by Cell Counting Kit-8 assay, migration was evaluated using the Transwell method, and differentiation was assessed by immunocytochemistry and immunofluorescence. In addition, the levels of proteins were detected by western blotting. High concentrations of TN-C promoted the migration of BMSCs. H₂O₂ at concentrations of 60–90 µmol/ml induced cell death in BMSCs, and thus, it was used to simulate oxidative stress in the microenvironment of acute myocardial infarction (AMI). High concentrations of TN-C were able to protect BMSCs from cell death, and promoted the migration of BMSCs (P<0.05). However, TAK-242 [the inhibitor of Toll-like receptor 4, (TLR4)] reduced the promoting effect of TN-C (P<0.05). By contrast, TN-C had no effect on the proliferation and differentiation of BMSCs. TN-C reduced the phosphorylation levels of p38 mitogen-activated protein kinase (MAPK), and increased the phosphorylation levels of Ser473 protein kinase B (AKT) and β-catenin, all of which were inhibited by TAK-242 (P<0.05). In the simulated AMI microenvironment, TN-C promoted the migration of BMSCs via TLR4-mediated signaling pathways, including MAPK, AKT and Wnt.

Intermittent Fasting Alleviates the Increase of Lipoprotein Lipase Expression in Brain of a Mouse Model of Alzheimer's Disease: Possibly Mediated by β-hydroxybutyrate

Intermittent fasting has been demonstrated to protect against Alzheimer's disease (AD), however, the mechanism is unclear. Histone acetylation and lipoprotein lipase (LPL) are involved in AD progression. Importantly, LPL has been documented to be regulated by histone deacetylases (HDACs) inhibitors (increase histone acetylation level) in adipocyte and mesenchymal stem cells, or by fasting in adipose and muscle tissues. In brain, however, whether histone acetylation or fasting regulates LPL expression is unknown. This study was designed to demonstrate intermittent fasting may protect against AD through increasing β-hydroxybutyrate, a HDACs inhibitor, to regulate LPL. We also investigated microRNA-29a expression associating with regulation of LPL and histone acetylation. The results showed LPL mRNA expression was increased and microRNA-29a expression was decreased in the cerebral cortex of AD model mice (APP/PS1), which were alleviated by intermittent fasting. No significant differences were found in the total expression of LPL protein (brain-derived and located in capillary endothelial cells from peripheral tissues) in the cerebral cortex of APP/PS1 mice. Further study indicated that LPL located in capillary endothelial cells was decreased in the cerebral cortex of APP/PS1 mice, which was alleviated by intermittent fasting. LPL and microRNA-29a expression were separately increased and down-regulated in 2 μM Aβ₂₅₋₃₅-exposed SH-SY5Y cells, but respectively decreased and up-regulated in 10 μM Aβ₂₅₋₃₅-exposed cells, which were all reversed by β-hydroxybutyrate. The increase of HDAC2/3 expression and the decrease of acetylated H3K9 and H4K12 levels were alleviated in APP/PS1 mice by intermittent fasting treatment, as well in 2 or 10 μM Aβ₂₅₋₃₅-exposed cells by β-hydroxybutyrate treatment. These findings above suggested the results from APP/PS1 mice were consistent with those from cells treated with 2 μM Aβ₂₅₋₃₅. Interestingly, LPL expression was reduced (0.2-folds) and microRNA-29a expression was up-regulated (1.7-folds) in HDAC2-silenced cells, but respectively increased (1.3-folds) and down-regulated (0.8-folds) in HDAC3-silenced cells. Furthermore, LPL expression was decreased in cells treated with microRNA-29a mimic and increased with inhibitor treatment. In conclusion, intermittent fasting inhibits the increase of brain-derived LPL expression in APP/PS1 mice partly through β-hydroxybutyrate-mediated down-regulation of microRNA-29a expression. HDAC2/3 may be implicated in the effect of β-hydroxybutyrate on microRNA-29a expression.

Lipoprotein Lipase Expression in Chronic Lymphocytic Leukemia: New Insights into Leukemic Progression

Lipoprotein lipase (LPL) is a central enzyme in lipid metabolism. Due to its catalytic activity, LPL is involved in metabolic pathways exploited by various solid and hematologic malignancies to provide an extra energy source to the tumor cell. We and others described a link between the expression of LPL in the tumor cell and a poor clinical outcome of patients suffering Chronic Lymphocytic Leukemia (CLL). This leukemia is characterized by a slow accumulation of mainly quiescent clonal CD5 positive B cells that infiltrates secondary lymphoid organs, bone marrow and peripheral blood. Despite LPL being found to be a reliable molecular marker for CLL prognosis, its functional role and the molecular mechanisms regulating its expression are still matter of debate. Herein we address some of these questions reviewing the current state of the art of LPL research in CLL and providing some insights into where currently unexplored questions may lead to.

MicroRNA-214 regulates smooth muscle cell differentiation from stem cells by targeting RNA-binding protein QKI

MicroRNA-214(miR-214) has been recently reported to regulate angiogenesis and embryonic stem cells (ESCs) differentiation. However, very little is known about its functional role in vascular smooth muscle cells (VSMCs) differentiation from ESCs. In the present study, we assessed the hypothesis that miR-214 and its target genes play an important role in VSMCs differentiation. Murine ESCs were seeded on collagen-coated flasks and cultured in differentiation medium for 2 to 8 days to allow VSMCs differentiation. miR-214 was significantly upregulated during VSMCs differentiation. miR-214 overexpression and knockdown in differentiating ESCs significantly promoted and inhibited VSMCs -specific genes expression, respectively. Importantly, miR-214 overexpression in ESCs promoted VSMCs differentiation in vivo. Quaking (QKI) was predicted as one of the major targets of miR-214, which was negatively regulated by miR-214. Luciferase assay showed miR-214 substantially inhibited wild type, but not the mutant version of QKI-3-UTR-luciferase activity in differentiating ESCs, further confirming a negative regulation role of miR-214 in QKI gene expression. Mechanistically, our data showed that miR-214 regulated VSMCs gene expression during VSMCs differentiation from ESCs through suppression of QKI. We further demonstrated that QKI down-regulated the expression of SRF, MEF2C and Myocd through transcriptional repression and direct binding to promoters of the SRF, MEF2c and Myocd genes. Taken together, we have uncovered a central role of miR-214 in ESC-VSMC differentiation, and successfully identified QKI as a functional modulating target in miR-214 mediated VSMCs differentiation.

Isothermal amplification detection of miRNA based on the catalysis of nucleases and voltammetric characteristics of silver nanoparticles

MiRNAs are a fascinating kind of biomolecule due to their vital functions in gene regulation and potential value as biomarkers for serious diseases including cancers. Exploiting convenient and sensitive methods for miRNA expression assays is imperative. In this study, we employ an exonuclease (RecJ_f) and a nicking endonuclease (Nt.BbvCI) to catalyse isothermal reactions for the amplified detection of miRNA. The degree of cyclical enzymatic amplification depends on the initial target miRNA level, which can determine the density of DNA probes bound on the electrode surface. Since DNA probes with an amino group at the 3' end are able to locate silver nanoparticles on the electrode, which provide intense stripping responses, the sensitive quantification of miRNA can be achieved. The proposed method has a limit of detection as low as 35 aM, with remarkable specificity, which offers a new approach for investigating miRNA networks and for clinical diagnosis applications.

Dual signaling evoked by oxidized LDLs in vascular cells

The oxidative theory of atherosclerosis relies on the modification of low density lipoproteins (LDLs) in the vascular wall by reactive oxygen species. Modified LDLs, such as oxidized LDLs, are thought to participate in the formation of early atherosclerotic lesions (accumulation of foam cells and fatty streaks), whereas their role in advanced lesions and atherothrombotic events is more debated, because antioxidant supplementation failed to prevent coronary disease events and mortality in intervention randomized trials. As oxidized LDLs and oxidized lipids are present in atherosclerotic lesions and are able to trigger cell signaling on cultured vascular cells and macrophages, it has been proposed that they could play a role in atherogenesis and atherosclerotic vascular remodeling. Oxidized LDLs exhibit dual biological effects, which are dependent on extent of lipid peroxidation, nature of oxidized lipids (oxidized phospholipids, oxysterols, malondialdehyde, α,β-unsaturated hydroxyalkenals), concentration of oxidized LDLs and uptake by scavenger receptors (e.g. CD36, LOX-1, SRA) that signal through different transduction pathways. Moderate concentrations of mildly oxidized LDLs are proinflammatory and trigger cell migration and proliferation, whereas higher concentrations induce cell growth arrest and apoptosis. The balance between survival and apoptotic responses evoked by oxidized LDLs depends on cellular systems that regulate the cell fate, such as ceramide/sphingosine-1-phosphate rheostat, endoplasmic reticulum stress, autophagy and expression of pro/antiapoptotic proteins. In vivo, the intimal concentration of oxidized LDLs depends on the influx (hypercholesterolemia, endothelial permeability), residence time and lipid composition of LDLs, oxidative stress intensity, induction of defense mechanisms (antioxidant systems, heat shock proteins). As a consequence, the local cellular responses to oxidized LDLs may stimulate inflammatory or anti-inflammatory pathways, angiogenic or antiangiogenic responses, survival or apoptosis, thereby contributing to plaque growth, instability, complication (intraplaque hemorrhage, proteolysis, calcification, apoptosis) and rupture. Finally, these dual properties suggest that oxLDLs could be implicated at each step of atherosclerosis development, from early fatty streaks to advanced lesions, depending on the nature and concentration of their oxidized lipid content.

MicroRNA-29a promotes smooth muscle cell differentiation from stem cells by targeting YY1

MicroRNA-29a (miR-29a) has been extensively studied in tumor biology and fibrotic diseases, but little is known about its functional roles in vascular smooth muscle cell (VSMC) differentiation from embryonic stem cells (ESCs). Using well-established VSMC differentiation models, we have observed that miR-29a induces VSMC differentiation from mouse ESCs by negatively regulating YY1, a transcription factor that inhibits muscle cell differentiation and muscle-specific gene expression. Moreover, gene expression levels of three VSMC specific transcriptional factors were up-regulated by miR-29a over-expression, but down-regulated by miR-29a inhibition or YY1 over-expression. Taken together, our data demonstrate that miR-29a and its target gene, YY1, play a regulatory role in VSMC differentiation from ESCs in vitro and in vivo.

Circulating miRNA in patients with non-alcoholic fatty liver disease and coronary artery disease

Background

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and coronary artery disease (CAD) is the cardiac manifestation of metabolic syndrome. NAFLD is strongly linked to CAD and hepatic steatosis is an independent risk factor for CAD and cardiac mortality. The pathogenic mechanism underlying this association remains poorly understood. In this study, we explored expression of circulating microRNAs (miRNAs) in patients with NAFLD and associated CAD.

Results

When compared to patients with NAFLD without CAD, patients with NAFLD and CAD had lower circulating levels of miR-132 (0.24±0.16 vs 0.30±0.11, p=0.03), while the circulating levels of miR-143 were higher (0.96±0.90 vs 0.64±0.77, p=0.02). The levels in circulation demonstrated trends opposite to previously observed intracellular levels in patients with CAD. In obese patients with NAFLD, lower circulating levels of miR-145 (1.42±1.00 vs 2.41±1.80), miR-211 (41.26±20.40 vs 57.56±25.45), miR-146a (2.13±1.40 vs 2.90±1.36) and miR-30c (6.92±4.99 vs 11.0±6.92) were detected when compared to lean patients with NAFLD. For miR-161 (0.59±1.19 vs 0.15±0.14) and miR-241 (0.28±0.29 vs 0.16±0.13), higher circulatory levels were detected in the obese patients with NAFLD. These observations suggest altered circulating levels of miRNAs that may serve to balance intracellular levels of miRNA in target tissues. Additional studies examining paired samples of target and producing tissues as well as respective plasma samples will help delineate the regulatory circuits governing the secretion and the uptake of miRNA in multitissue diseases.

MicroRNA-27 Prevents Atherosclerosis by Suppressing Lipoprotein Lipase-Induced Lipid Accumulation and Inflammatory Response in Apolipoprotein E Knockout Mice

Atherosclerotic lesions are lipometabolic disorder characterized by chronic progressive inflammation in arterial walls. Previous studies have shown that macrophage-derived lipoprotein lipase (LPL) might be a key factor that promotes atherosclerosis by accelerating lipid accumulation and proinflammatory cytokine secretion. Increasing evidence indicates that microRNA-27 (miR-27) has beneficial effects on lipid metabolism and inflammatory response. However, it has not been fully understood whether miR-27 affects the expression of LPL and subsequent development of atherosclerosis in apolipoprotein E knockout (apoE KO) mice. To address these questions and its potential mechanisms, oxidized low-density lipoprotein (ox-LDL)-treated THP-1 macrophages were transfected with the miR-27 mimics/inhibitors and apoE KO mice fed high-fat diet were given a tail vein injection with miR-27 agomir/antagomir, followed by exploring the potential roles of miR-27. MiR-27 agomir significantly down-regulated LPL expression in aorta and peritoneal macrophages by western blot and real-time PCR analyses. We performed LPL activity assay in the culture media and found that miR-27 reduced LPL activity. ELISA showed that miR-27 reduced inflammatory response as analyzed in vitro and in vivo experiments. Our results showed that miR-27 had an inhibitory effect on the levels of lipid both in plasma and in peritoneal macrophages of apoE KO mice as examined by HPLC. Consistently, miR-27 suppressed the expression of scavenger receptors associated with lipid uptake in ox-LDL-treated THP-1 macrophages. In addition, transfection with LPL siRNA inhibited the miR-27 inhibitor-induced lipid accumulation and proinflammatory cytokines secretion in ox-LDL-treated THP-1 macrophages. Finally, systemic treatment revealed that miR-27 decreased aortic plaque size and lipid content in apoE KO mice. The present results provide evidence that a novel antiatherogenic role of miR-27 was closely related to reducing lipid accumulation and inflammatory response via downregulation of LPL gene expression, suggesting a potential strategy to the diagnosis and treatment of atherosclerosis.

Direct Peritoneal Resuscitation Alters Hepatic miRNA Expression after Hemorrhagic Shock

BACKGROUND

MicroRNAs (miRNAs) are small segments of noncoding RNA that regulate gene expression and protein function, and therefore are key regulators of cellular processes including those of the inflammatory cascade after hemorrhagic shock (HS). We have previously shown that direct peritoneal resuscitation (DPR), as an adjunct to traditional IV fluid resuscitation, improves visceral blood flow and reduces pro-inflammatory cytokines released during HS. The effects of DPR on hepatic miRNA (miR) expression patterns after resuscitated HS are not known.

STUDY DESIGN

Male Sprague-Dawley rats were divided into 3 groups: sham (no HS); conventional resuscitation (CR; HS, then resuscitated with shed blood and 2 volumes of saline); and DPR (CR plus 30 mL peritoneal dialysis solution). Animals were sacrificed at 4 hours, and miRNAs were measured using reverse transcription polymerase chain reaction.

RESULTS

Use of DPR downregulated 68 of 92 hepatic miRNAs compared with only 2 of 92 upregulated when compared with CR alone, p < 0.01). Specifically, miR-9-5p, miR-122-5p, and miR-146, which regulate NFκB, were downregulated 4.1-, 3.4-, and 0.86-fold, respectively; miR-29a and miR-126 were upregulated 0.88- and 3.7-fold when DPR was compared with CR.

CONCLUSIONS

Adding DPR downregulated most hepatic miRNAs compared with CR alone. Some miRNAs were affected more significantly, suggesting that although this clinical intervention causes a near-global downregulation of hepatic miRNA, it still targets specific inflammatory pathways. Use of DPR for resuscitation of patients in HS may reduce hepatic inflammation to improve patient outcomes after hemorrhage.

MicroRNA-29a: A potential biomarker in the development of intracranial aneurysm

AIM

To identify serum microRNA-29a (miR-29a) level in patients with intracranial aneurysm and its role in the development of intracranial aneurysm (IA).

METHODS

Case group included 165 IA patients hospitalized in the department of neurosurgery between January 2010 and January 2012 while control group enrolled 220 healthy volunteers. Morning fasting blood samples were collected from peripheral vein. RT-PCR was used for miR-29a detection. Receiver Operating Characteristic (ROC) curve was drawn. Survival curves were drawn for survival analysis with Kaplan-Meier method and Long-rank test was conducted. MiR-29a expression Glasgow Prognosis Score (GOS) was used for prognosis scaling. Multivariate Cox proportional hazards regression analysis was performed for prognosis analysis. Results Cases had significantly higher miR-29a expressions than controls (P<0.05). ROC curve analysis indicated that miR-29a expression in IA had high effectiveness in IA diagnosis. Close associations were identified between miR-29a expression and rupture, Hunt-Hess level and surgical timing (all P<0.05). GOS strongly associated with history of hypertension, aneurysm location, rupture, Hunt-Hess level and miR-29a expression. Patients with low miR-29a expression had longer disease-free survival (DFS) and overall survival (OS) than those with high miR-29a expression (both P<0.05). MiR-29a expression, tumor aneurysm, rupture and Hunt-Hess were risk factors to the prognosis of IA (all P<0.05).

CONCLUSION

MiR-29a may be closely related to IA development and therefore could be a useful predicator of IA prognosis, providing a new target for IA therapy.

Deep Sequencing and Screening of Differentially Expressed MicroRNAs Related to Milk Fat Metabolism in Bovine Primary Mammary Epithelial Cells

Milk fat is a key factor affecting milk quality and is also a major trait targeted in dairy cow breeding. To determine how the synthesis and the metabolism of lipids in bovine milk is regulated at the miRNA level, primary mammary epithelial cells (pMEC) derived from two Chinese Holstein dairy cows that produced extreme differences in milk fat percentage were cultured by the method of tissue nubbles culture. Small RNA libraries were constructed from each of the two pMEC groups, and Solexa sequencing and bioinformatics analysis were then used to determine the abundance of miRNAs and their differential expression pattern between pMECs. Target genes and functional prediction of differentially expressed miRNAs by Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes analysis illustrated their roles in milk fat metabolism. Results show that a total of 292 known miRNAs and 116 novel miRNAs were detected in both pMECs. Identification of known and novel miRNA candidates demonstrated the feasibility and sensitivity of sequencing at the cellular level. Additionally, 97 miRNAs were significantly differentially expressed between the pMECs. Finally, three miRNAs including bta-miR-33a, bta-miR-152 and bta-miR-224 whose predicted target genes were annotated to the pathway of lipid metabolism were screened and verified by real-time qPCR and Western-blotting experiments. This study is the first comparative profiling of the miRNA transcriptome in pMECs that produce different milk fat content.

Transcriptome profiling and pathway analysis of hepatotoxicity induced by tris (2-ethylhexyl) trimellitate (TOTM) in mice

Tris (2-ethylhexyl) trimellitate (TOTM) is commonly used as an alternative plasticizer for medical devices. But very little information was available on its biological effects. In this study, we investigated toxicity effects of TOTM on hepatic differential gene expression analyzed by using high-throughput sequencing analysis for over-represented functions and phenotypically anchored to complementary histopathologic, and biochemical data in the liver of mice. Among 1668 candidate genes, 694 genes were up-regulated and 974 genes were down-regulated after TOTM exposure. Using Gene Ontology analysis, TOTM affected three processes: the cell cycle, metabolic process and oxidative activity. Furthermore, 11 key genes involved in the above processes were validated by real time PCR. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that these genes were involved in the cell cycle pathway, lipid metabolism and oxidative process. It revealed the transcriptome gene expression response to TOTM exposure in mouse, and these data could contribute to provide a clearer understanding of the molecular mechanisms of TOTM-induced hepatotoxicity in human.

miR-29a Participated in Nacre Formation and Immune Response by Targeting Y2R in Pinctada martensii

miR-29a is a conserved miRNA that participates in bone formation and immune response in vertebrates. miR-29a of Pinctada martensii (Pm-miR-29a) was identified in the previous research though deep sequencing. In this report, the precise sequence of mature Pm-miR-29a was validated using miRNA rapid amplification of cDNA ends (miR-RACE) technology. The precursor sequence of Pm-miR-29a was predicted to have 87 bp. Stem loop qRT-PCR analysis showed that Pm-miR-29a was easily detected in all the tissues, although expressions in the mantle and gill were low. The microstructure showed the disrupted growth of the nacre after Pm-miR-29a over-expression, which was induced by mimic injection into P. martensii. Results of the target analysis indicated that neuropeptide Y receptor type 2 (Y2R) was the potential target of Pm-miR-29a. Meanwhile, Pm-miR-29a mimics could obviously inhibit the relative luciferase activity of the reporter containing 3′ UTR (Untranslated Regions) of the Y2R gene. Furthermore, the expression of Y2R was downregulated whereas expressions of interleukin 17 (IL-17) and nuclear factor κB (NF-κB) were upregulated after Pm-miR-29a over-expression in the mantle and gill, thereby suggesting that Pm-miR-29a could activate the immune response of the pearl oyster. Results showed that Pm-miR-29a was involved in nacre formation and immune response by regulating Y2R in pearl oyster P. martensii.

Scavenger receptors and non-coding RNAs: relevance in atherogenesis

Scavenger receptors (SRs), which recognize modified low-density lipoprotein (LDL) by oxidation or acetylation, are a group of receptors on plasma membrane of macrophages and other cell types. These receptors by facilitating modified LDL uptake are a primary step in the intracellular accumulation of modified LDL and formation of fatty streak. Non-coding RNAs (ncRNAs) are a group of functional RNA nucleotides that are not translated into protein, and include microRNAs (miRs), snoRNAs, siRNAs, snRNAs, exRNAs, piRNAs, and the long ncRNAs (lncRNAs). Recently, ncRNAs have received much attention due to their effects in a variety of disease states such as atherosclerotic cardiovascular disease and cancers. A host of ncRNAs, such as miRs and lncRNAs, have been found to be involved in the regulation of SRs and the inflammatory cascade and subsequently atherosclerosis. Here, we review this important area to create interest in this growing field among researchers and clinicians alike.

MicroRNA Profiling of B Cell Subsets from Systemic Lupus Erythematosus Patients Reveals Promising Novel Biomarkers

MicroRNAs control the differentiation and function of B cells, which are considered key elements in the pathogenesis of systemic lupus erythematosus (SLE). However, a common micro(mi)RNA signature has not emerged since published data includes patients of variable ethnic background, type of disease, and organ involvement, as well as heterogeneous cell populations. Here, we aimed at identifying a miRNA signature of purified B cells from renal and non-renal severe SLE patients of Latin American background, a population known to express severe disease. Genome-wide miRNA expression analyses were performed on naive and memory B cells and revealed two categories of miRNA signatures. The first signature represents B cell subset-specific miRNAs deregulated in SLE: 11 and six miRNAs discriminating naive and memory B cells of SLE patients from healthy controls (HC), respectively. Whether the miRNA was up or down-regulated in memory B cells as compared with naive B cells in HC, this difference was abolished in SLE patients, and vice versa. The second signature identifies six miRNAs associated with specific pathologic features affecting renal outcome, providing a further understanding for SLE pathogenesis. Overall, the present work provided promising biomarkers in molecular diagnostics for disease severity as well as potential new targets for therapeutic intervention in SLE.

Identification of novel targets for seasonal allergic rhinitis during and outside the pollen season by microarray analysis

CONCLUSION

FOS, JUN, and DUSP1 could be used as candidate targets for the treatment of seasonal allergic rhinitis (SAR) during the pollen season, while KLF4 and CD163 could be used as candidate targets outside the pollen season.

OBJECTIVES

The aim of this study is to screen novel genes related to SAR during and outside the pollen season, by using microarray analysis.

METHODS

The mRNA expression profile (GSE50101) of CD4(+) T cells from SAR and healthy controls during and outside the pollen season was downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) were then screened with the cut-off criteria of fold change larger than 1.5 and p-value less than 0.05.

RESULTS

A total of 47 DEGs were identified. Ten DEGs were shared by SAR patient samples during and outside the pollen season, while four and 23 DEGs were specific to during and outside the pollen season, respectively. Five miRNAs were screened in this study. Among these miRNAs, miR-139, miR-101, miR-29A, and miR-181 could target FOS; miR-200 and miR-29A could target KLF4; miR-101 and miR-200 could target DUSP1; miR-139 and miR-181 could target JUN and CD163, respectively.

miR-29a promotes scavenger receptor A expression by targeting QKI (quaking) during monocyte-macrophage differentiation

Monocyte differentiation into macrophages results in upregulation of miR-29a and scavenger receptor A (SRA) expression, while the expression of RNA binding protein, QKI is suppressed. Since SRA is a functionally important protein in atherosclerosis, it is imperative to understand the various mechanisms involved in its regulation specially the mechanism involving miR-29a. There are individual studies linking miR-29a to SRA or QKI to monocyte differentiation but there is no evidence of any linkage among them. Therefore, we intend to investigate the association among these three, if any, in terms of regulation of SRA expression. Hence, in this study, the differentiated macrophages were initially transfected with miR-29a or its inhibitor and it was shown that QKI is a direct target of mir-29a. In addition, it was also observed by bioinformatics analysis that 3'UTR in SRA mRNA has QKI binding site. So, we attempted to further understand the role of QKI in SRA regulation. The macrophages were manipulated either with overexpression of QKI or by its ablation and it was observed that QKI suppressed SRA at the transcriptional level. Moreover, with the help of luciferase reporter vector, it was shown that QKI inhibited SRA transcription by binding to QRE region in its 3'UTR mRNA. Furthermore, to link the QKI mediated regulation of SRA expression with its functional activity; we analyzed lipid uptake capacity of macrophages transfected with either ectopic OKI plasmid or ablated for QKI. It was observed that, indeed, QKI upregulation inhibits lipid uptake by repressing SRA expression. Overall, our study demonstrates that miR-29a inhibits QKI, which in turn results in upregulation of SRA and lipid uptake.

MicroRNAs affect dendritic cell function and phenotype

MicroRNA (miRNA) are small, non-coding RNA molecules that have been linked with immunity through regulating/modulating gene expression. A role for these molecules in T-cell and B-cell development and function has been well established. An increasing body of literature now highlights the importance of specific miRNA in dendritic cell (DC) development as well as their maturation process, antigen presentation capacity and cytokine release. Given the unique role of DC within the immune system, linking the innate and adaptive immune responses, understanding how specific miRNA affect DC function is of importance for understanding disease. In this review we summarize recent developments in miRNA and DC research, highlighting the requirement of miRNA in DC lineage commitment from bone marrow progenitors and for the development of subsets such as plasmacytoid DC and conventional DC. In addition, we discuss how infections and tumours modulate miRNA expression and consequently DC function.

MicroRNA-29a induces apoptosis via increasing the Bax:Bcl-2 ratio in dermal fibroblasts of patients with systemic sclerosis

The most prominent feature of systemic sclerosis (SSc) and other diseases associated with fibrosis is the prolonged activation of fibroblasts not eliminated by apoptosis, hence characterized by accumulation of more extra cellular matrix (ECM). We tend to verify if microRNA-29a (miR-29a) as an anti-fibrotic factor could induce apoptosis in SSc fibroblasts. We did not detect apoptosis in SSc fibroblasts. We found that Bcl-2 expression was upregulated in SSc fibroblasts and the ratio of Bax:Bcl-2 in these cells was significantly lower (p = 0.02) compared to normal fibroblasts. Transfection of both SSc and transforming growth factor-β (TGF-β) stimulated fibroblasts by miR-29a mimic, significantly decreased the expression of two anti-apoptotic members of the Bcl-2 family, Bcl-2 (p = 0.0005, p = 0.01) and Bcl-XL (p = 0.0001, p = 0.006), resulted in enhanced Bax:Bcl-2 ratio and induced a high rate of apoptosis. Recently, miR-29 has been introduced as an anti-fibrotic factor with potential therapeutic effect on SSc. Until now, it has not been proposed whether there is a relationship between miR-29a and apoptosis in SSc. According to our results, it seems that miR-29a is a potent inducer of apoptosis in SSc fibroblasts and an attenuator of ECM production in these cells. MiR-29a disrupted the expression profiling of Bcl-2 family proteins (Bax, Bcl-2 and Bcl-XL) which is the central point of dynamic life-death rheostat in many apoptotic pathways. Furthermore, dermal fibroblasts from patients with SSc showed elevation in TNF-α mRNA levels, while restoration of miR-29a decreases TNF-α production in these cells. Although further molecular studies are necessary to investigate the underlying apoptotic pathways, the present findings suggest that anti-fibrotic and pro-apoptotic properties of miR-29a could provide novel benefits toward the development of fibroblast-specific anti-fibrotic therapies.

Sugar-based amphiphilic polymers for biomedical applications: from nanocarriers to therapeutics

Various therapeutics exhibit unfavorable physicochemical properties or stability issues that reduce their in vivo efficacy. Therefore, carriers able to overcome such challenges and deliver therapeutics to specific in vivo target sites are critically needed. For instance, anticancer drugs are hydrophobic and require carriers to solubilize them in aqueous environments, and gene-based therapies (e.g., siRNA or pDNA) require carriers to protect the anionic genes from enzymatic degradation during systemic circulation. Polymeric micelles, which are self-assemblies of amphiphilic polymers (APs), constitute one delivery vehicle class that has been investigated for many biomedical applications. Having a hydrophobic core and a hydrophilic shell, polymeric micelles have been used as drug carriers. While traditional APs are typically comprised of nondegradable block copolymers, sugar-based amphiphilic polymers (SBAPs) synthesized by us are comprised of branched, sugar-based hydrophobic segments and a hydrophilic poly(ethylene glycol) chain. Similar to many amphiphilic polymers, SBAPs self-assemble into polymeric micelles. These nanoscale micelles have extremely low critical micelle concentrations offering stability against dilution, which occurs with systemic administration. In this Account, we illustrate applications of SBAPs for anticancer drug delivery via physical encapsulation within SBAP micelles and chemical conjugation to form SBAP prodrugs capable of micellization. Additionally, we show that SBAPs are excellent at stabilizing liposomal delivery systems. These SBAP-lipid complexes were developed to deliver hydrophobic anticancer therapeutics, achieving preferential uptake in cancer cells over normal cells. Furthermore, these complexes can be designed to electrostatically complex with gene therapies capable of transfection. Aside from serving as a nanocarrier, SBAPs have also demonstrated unique bioactivity in managing atherosclerosis, a major cause of cardiovascular disease. The atherosclerotic cascade is usually triggered by the unregulated uptake of oxidized low-density lipoprotein, a cholesterol carrier, in macrophages of the blood vessel wall; SBAPs can significantly inhibit oxidized low-density lipoprotein uptake in macrophages and abrogate the atherosclerotic cascade. By modification of various functionalities (e.g., branching, stereochemistry, hydrophobicity, and charge) in the SBAP chemical structure, SBAP bioactivity was optimized, and influential structural components were identified. Despite the potential of SBAPs as atherosclerotic therapies, blood stability of the SBAP micelles was not ideal for in vivo applications, and means to stabilize them were pursued. Using kinetic entrapment via flash nanoprecipitation, SBAPs were formulated into nanoparticles with a hydrophobic solute core and SBAP shell. SBAP nanoparticles exhibited excellent physiological stability and enhanced bioactivity compared with SBAP micelles. Further, this method enables encapsulation of additional hydrophobic drugs (e.g., vitamin E) to yield a stable formulation that releases two bioactives. Both as nanoscale carriers and as polymer therapeutics, SBAPs are promising biomaterials for medical applications.

MicroRNA-590 attenuates lipid accumulation and pro-inflammatory cytokine secretion by targeting lipoprotein lipase gene in human THP-1 macrophages

BACKGROUND

Accumulating evidence suggests that microRNA-590 (miR-590) has protective effects on cardiovascular diseases, but the mechanism is unknown. Interestingly, previous studies from our laboratory and others have shown that macrophage-derived lipoprotein lipase (LPL) might accelerate atherosclerosis by promoting lipid accumulation and inflammatory response. However, the regulation of LPL at the post-transcriptional level by microRNAs has not been fully understood. In this study, we explored whether miR-590 affects the expression of LPL and its potential subsequent effects on lipid accumulation and pro-inflammatory cytokine secretion in human THP-1 macrophages.

METHODS AND RESULTS

Using bioinformatics analyses and dual-luciferase reporter assays, we found that miR-590 directly inhibited LPL protein and mRNA expression by targeting LPL 3'UTR. LPL Activity Assays showed that miR-590 reduced LPL activity in the culture media. Oil Red O staining and high-performance liquid chromatography assays showed that miR-590 had inhibitory effects on the lipid accumulation in human THP-1 macrophages. We also illustrated that miR-590 alleviated pro-inflammatory cytokine secretion in human THP-1 macrophages as measured by ELISA. With the method of small interfering RNA, we found that LPL siRNA can inhibit the miR-590 inhibitor-induced increase in lipid accumulation and secretion of pro-inflammatory cytokines in oxLDL-treated human THP-1 macrophages.

CONCLUSIONS

MiR-590 attenuates lipid accumulation and pro-inflammatory cytokine secretion by targeting LPL gene in human THP-1 macrophages. Therefore, targeting miR-590 may offer a promising strategy to treat atherosclerotic cardiovascular diseases.

The role of miR-29 family members in malignant hematopoiesis

AIMS

MicroRNAs of the miR-29 family members were one of the first microRNAs identified as possible therapeutic agents in malignant hematopoiesis. The aim of our review is to summarize the current state of knowledge on miR-29 family members.

METHODS

We performed literature searches involving miR-29 family members and their relationship to individual hematological malignancies, namely acute myeloid leukemia (AML), chronic lymphoblastic leukemia (CLL) and chronic myeloid leukemia (CML). We also searched for subgroups of hematological malignancies, e.g. multiple myeloma, that are regarded as members of the acute or chronic types of leukemias.

RESULTS

A number of genes appear to be regulated by miR-29 family members in various physiological and pathological situations. In our view regulation of Tcl-1, Mcl-1 and DNA methyltransferases is relevant in case of hematological malignancies, hence these are the focus of this review. miR-29 family members also function during normal T-cell and B-cell development.

CONCLUSION

MiR-29 family members appear to govern some general features in commonly heterogenous hematological malignancies and therefore form a potential target for treatment.

Epithelial SCAP/INSIG/SREBP signaling regulates multiple biological processes during perinatal lung maturation

Pulmonary surfactant is required for lung function at birth and throughout postnatal life. Defects in the surfactant system are associated with common pulmonary disorders including neonatal respiratory distress syndrome and acute respiratory distress syndrome in children and adults. Lipogenesis is essential for the synthesis of pulmonary surfactant by type II epithelial cells lining the alveoli. This study sought to identify the role of pulmonary epithelial SREBP, a transcriptional regulator of cellular lipid homeostasis, during a critical time period of perinatal lung maturation in the mouse. Genome wide mRNA expression profiling of lung tissue from transgenic mice with epithelial-specific deletions of Scap (Scap^Δ/Δ, resulting in inactivation of SREBP signaling) or Insig1 and Insig2 (Insig1/2^Δ/Δ, resulting in activation of SREBP signaling) was assessed. Differentially expressed genes responding to SREBP perturbations were identified and subjected to functional enrichment analysis, pathway mapping and literature mining to predict upstream regulators and transcriptional networks regulating surfactant lipid homeostasis. Through comprehensive data analysis and integration, time dependent effects of epithelial SCAP/INSIG/SREBP deletion and defined SCAP/INSIG/SREBP-associated genes, bioprocesses and downstream pathways were identified. SREBP signaling influences epithelial development, cell death and cell proliferation at E17.5, while primarily influencing surfactant physiology, lipid/sterol synthesis, and phospholipid transport after birth. SREBP signaling integrated with the Wnt/β-catenin and glucocorticoid receptor signaling pathways during perinatal lung maturation. SREBP regulates perinatal lung lipogenesis and maturation through multiple mechanisms by interactions with distinct sets of regulatory partners.

MicroRNAs involved in the lipid metabolism and their possible implications for atherosclerosis development and treatment

Hyperlipidemia is a well-accepted risk factor in the development of atherosclerosis. MicroRNAs (miRNAs), a novel class of posttranscriptional regulators of gene expression, are involved in a variety of biological and pathological processes, including the regulation of the lipid metabolism and atherosclerosis. As our knowledge of miRNAs expands, a new class of "circulating miRNAs" has recently been described. It includes miRNAs which may be found in various bodily fluids packaged in microvesicles/exosomes, or bound to specific transporting proteins. High-density lipoprotein (HDL) particles have been identified as one such carrier. As this class of miRNAs likely plays a role in intercellular communication, it may also contribute to the atherosclerosis development and progression. This review aims to provide a comprehensive explanation of the roles of distinct miRNAs involved in the regulation of the lipid metabolism. These microRNAs seem to be promising therapeutic agents, as documented in rodents and African green monkeys. The second part of the review focuses on circulating miRNAs and their involvement in the atherosclerosis, especially as their levels have been described as altered in patients with dyslipidemia/hyperlipidemia. Special emphasis is placed on miRNAs transported in a complex with HDL particles and on those which may be considered potential atherosclerosis biomarkers.

MicroRNA-27a/b regulates cellular cholesterol efflux, influx and esterification/hydrolysis in THP-1 macrophages

RATIONALE

Macrophage cholesterol homeostasis maintenance is the result of a balance between influx, endogenous synthesis, esterification/hydrolysis and efflux. Excessive accumulation of cholesterol leads to foam cell formation, which is the major pathology of atherosclerosis. Previous studies have shown that miR-27 (miR-27a and miR-27b) may play a key role in the progression of atherosclerosis.

OBJECTIVE

We set out to investigate the molecular mechanisms of miR-27a/b in intracellular cholesterol homeostasis.

METHODS AND RESULTS

In the present study, our results have shown that the miR-27 family is highly conserved during evolution, present in mammals and directly targets the 3' UTR of ABCA1, LPL, and ACAT1. apoA1, ABCG1 and SR-B1 lacking miR-27 bind sites should not be influenced by miR-27 directly. miR-27a and miR-27b directly regulated the expression of endogenous ABCA1 in different cells. Treatment with miR-27a and miR-27b mimics reduced apoA1-mediated cholesterol efflux by 33.08% and 44.61% in THP-1 cells, respectively. miR-27a/b also regulated HDL-mediated cholesterol efflux in THP-1 macrophages and affected the expression of apoA1 in HepG2 cells. However, miR-27a/b had no effect on total cellular cholesterol accumulation, but regulated the levels of cellular free cholesterol and cholesterol ester. We further found that miR-27a/b regulated the expression of LPL and CD36, and then affected the ability of THP-1 macrophages to uptake Dil-oxLDL. Finally, we identified that miR-27a/b regulated cholesterol ester formation by targeting ACAT1 in THP-1 macrophages.

CONCLUSION

These findings indicate that miR-27a/b affects the efflux, influx, esterification and hydrolysis of cellular cholesterol by regulating the expression of ABCA1, apoA1, LPL, CD36 and ACAT1.

Combinatorial regulation of lipoprotein lipase by microRNAs during mouse adipogenesis

MicroRNAs (miRNAs) regulate gene expression directly through base pairing to their targets or indirectly through participating in multi-scale regulatory networks. Often miRNAs take part in feed-forward motifs where a miRNA and a transcription factor act on shared targets to achieve accurate regulation of processes such as cell differentiation. Here we show that the expression levels of miR-27a and miR-29a inversely correlate with the mRNA levels of lipoprotein lipase (Lpl), their predicted combinatorial target, and its key transcriptional regulator peroxisome proliferator-activated receptor gamma (Pparg) during 3T3-L1 adipocyte differentiation. More importantly, we show that Lpl, a key lipogenic enzyme, can be negatively regulated by the two miRNA families in a combinatorial fashion on the mRNA and functional level in maturing adipocytes. This regulation is mediated through the Lpl 3'UTR as confirmed by reporter gene assays. In addition, a small mathematical model captures the dynamics of this feed-forward motif and predicts the changes in Lpl mRNA levels upon network perturbations. The obtained results might offer an explanation to the dysregulation of LPL in diabetic conditions and could be extended to quantitative modeling of regulation of other metabolic genes under similar regulatory network motifs.