Monocyte exposure to fine particulate matter results in miRNA release: A link between air pollution and potential clinical complication

Chronic exposure to PM_2.5 contributes to the pathogenesis of numerous disorders, although the underlying mechanisms remain unknown. The study investigated whether exposure of human monocytes to PM_2.5 is associated with alterations in miRNAs. Monocytes were exposed in vitro to PM_2.5 collected during winter and summer, followed by miRNA isolation from monocytes. Additionally, in 140 persons chronically exposed to air pollution, some miRNA patterns were isolated from serum seasonally. Between-season differences in chemical PM_2.5 composition were observed. Some miRNAs were expressed both in monocytes and in human serum.MiR-34c-5p and miR-223-5p expression was more pronounced in winter. Bioinformatics analyses showed that selected miRNAs were involved in the regulation of several pathways. The expression of the same miRNA species in monocytes and serum suggests that these cells are involved in the production of miRNAs implicated in the development of disorders mediated by inflammation, oxidative stress, proliferation, and apoptosis after exposure to PM_2.5.     

Evaluation of microRNA responses in ARPE-19 cells against the oxidative stress

Purpose: This study aimed to determine microRNA (miRNA) expression profile of human retinal pigment epithelium cell (ARPE-19) against the oxidative stress induced by hydrogen peroxide (H₂O₂).

Methods: ARPE-19 cells were incubated with different concentrations of H₂O₂ (200, 600 and 800?μM) for 18?h, and then cell viability, vascular endothelial growth factor levels and total oxidant status were evaluated. Expressions of 1152 miRNA were determined by quantitative real-time PCR in each group.

Results: Expressions of 90 miRNA were significantly changed in the ARPE-19 cells incubated with H₂O₂ compared to control group. However, miR-143-3p was only found to be expressed in groups incubated with H₂O₂. While 24 miRNA (hsa-miR-200c-3p, miR-192-5p, miR-194-5p, miR-141-3p, miR-658, miR-18?b-5p, miR-486-5p, miR-525-3p, miR-493-3p, miR-518d-3p, miR-29?b-1-5p, miR-675-3p, miR-1238-3p, miR-195-3p, miR-1539, miR-490-5p, miR-3200-5p, miR-1273d, miR-130a-5p, miR-30?b-5p, miR-1247-5p, miR-1910-5p, miR27a-5p and miR-200?b-3p) upregulated due to the increased dose of H₂O₂, nine miRNA (hsa-miR-96-5p, miR-33a-5p, miR-345-5p, miR-106?b-3p, miR-1285-3p, miR-23?b-5p, miR-27?b-5p, miR-103a-3p and miR-4289) were also found to be downregulated.

Conclusion: This study suggests that oxidative stress may be an important factor on expression of miRNAs in ARPE-19 cells. These miRNAs may have a role in the pathogenesis of age-related macular degeneration related to oxidative stress. However, this relationship needs to be examined in new studies by evaluation of pathways and target genes.     

Integrative analysis of mRNA and microRNA expression of a human alveolar epithelial cell(A549) exposed to water and organic‐soluble extract from particulate matter (PM)2.5

MicroRNA (miRNA) is now attracting attention as a powerful negative regulator of messenger RNA(mRNA) levels, and is implicated in the modulation of important mRNA networks involved in toxicity. In this study, we assessed the effects of particulate matter 2.5 (PM_2.5), one of the most significant air pollutants, on miRNA and target gene expression. We exposed human alveolar epithelial cell (A549) to two types of PM_2.5[water (W‐PM_2.5) and organic (O‐PM_2.5) soluble extracts] and performed miRNA microarray analysis. A total of 37 miRNAs and 62 miRNAs were altered 1.3‐fold in W‐PM_2.5 and O‐PM_2.5, respectively. Integrated analyses of miRNA and mRNA expression profiles identified negative correlations between miRNA and mRNA in both W‐PM_2.5 and O‐PM_2.5 exposure groups. Gene ontology and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses showed that the 35 W‐PM_2.5 target genes are involved in responses to nutrients, positive regulation of biosynthetic processes, positive regulation of nucleobase, nucleoside, and nucleotide, and nucleic acid metabolic processes; while the 69 O‐PM_2.5 target genes are involved in DNA replication, cell cycle processes, the M phase, and the cell cycle check point. We suggest that these target genes may play important roles in PM_2.5‐induced respiratory toxicity by miRNA regulation. These results demonstrate an integrated miRNA‐mRNA approach for identifying molecular events induced by environmental pollutants in an in vitro human model. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 302–310, 2017.     

Effects of ambient ozone exposure on circulating extracellular vehicle microRNA levels in coronary artery disease patients

ABSTRACT

Exposure to ambient air pollutants such as ozone (O₃) and particulate matter (PM) is associated with increased cardiovascular morbidity and rate of mortality, but the underlying biological mechanisms have yet to be described. Emerging evidence shows that extracellular vehicle (EV) microRNAs (miRNAs) may facilitate cell-to-cell and organ-to-organ communications and play a role in the air pollution-induced cardiovascular effects. This study aims to explore the association between air pollutant exposure and miRNA changes related to cardiovascular diseases. Using a panel study design, 14 participants with coronary artery diseases were enrolled in this study. Each participant had up to 10 clinical visits and their plasma samples were collected and measured for expression of miRNA-21 (miR-21), miR-126, miR-146, miR-150, and miR-155. Mixed effects models adjusted for temperature, humidity, and season were used to examine the association between miRNA levels and exposure to 8-hr O₃ or 24-hr PM_2.5 up to 4 days prior. Results demonstrated that miR-150 expression was positively associated with O₃ exposure at 1–4 days lag and 5day moving average while miR-155 expression tracked with O₃ exposure at lag 0. No significant association was found between miRNA expression and ambient PM_2.5 at any time point. β-blocker and diabetic medication usage significantly modified the correlation between O₃ exposure and miR-150 expression where the link was more prominent among non-users. In conclusion, evidence indicated an association between exposure to ambient O₃ and circulating levels of EV miR-150 and miR-155 was observed. These findings pointed to a future research direction involving miRNA-mediated mechanisms of O₃-induced cardiovascular effects.     

Differential microRNAs expression in seminal plasma of normospermic patients with different sperm DNA fragmentation indexes

Sperm DNA fragmentation index (SDF), as an important supplement to routine semen parameters, has been proposed to discriminate between fertile and infertile men, and predicts the outcomes of natural conception and in vitro fertilization. Unfortunately there are uncertainty and contradictory evidences regarding the importance of SDF. An important reason is the fact that significant and fundamental research about SDF is rare. This study was designed to characterize the microRNA (miRNA) expression profile in seminal plasma of normospermic patients with different SDF and their implications in human fertility. Using next-generation sequencing (NGS), a total of 897 human miRNAs were detected from 10 seminal plasma samples, out of which 431 differentially expressed miRNAs in 5 pairs of seminal plasma samples (each pair of seminal plasma samples obtained from the same male), with 14 miRNAs were identified in all the pairs. According to the fold change and expression level, 7 miRNAs including miR-374b-5p, miR-429, hsa-miR-26b-5p, miR-21−5p, miR-4257, miR-135b-5p and miR-134−5p were selected for further excavation. MiR-374b-5p and miR-26b-5p were significantly different in 3 sets of individual seminal plasma samples with different SDF from total 90 infertile patients (30 patients each set). Our results demonstrate that the profile of miR-374b and miR-26b with significantly decreased expression could be used as a first indication of increased SDF. And miR-374b and miR-26b could serve as adjunct biomarkers for the diagnosis of idiopathic infertile males.     

Differential and unique patterns of synaptic miRNA expression in dorsolateral prefrontal cortex of depressed subjects

Altered synaptic plasticity is often associated with major depressive disorder (MDD). Disease-associated changes in synaptic functions are tightly correlated with altered microRNA (miRNA) expression. Here, we examined the role of miRNAs and their functioning at the synapse in MDD by examining miRNA processing machinery at synapse and sequencing miRNAs and analyzing their functions in synaptic and total tissue fractions obtained from dorsolateral prefrontal cortex (dlPFC) of 15 MDD and 15 matched non-psychiatric control subjects. A total of 333 miRNAs were reliably detected in the total tissue fraction. Multiple testing following the Benjamini–Hochberg false discovery rate [FDR] showed that 18 miRNAs were significantly altered (1 downregulated 4 up and 13 downregulated; p < 0.05) in MDD subjects. Out of 351 miRNAs reliably expressed in the synaptic fraction, 24 were uniquely expressed at synapse. In addition, 8 miRNAs (miR-215-5p, miR-192-5p, miR-202-5p, miR-19b-3p, miR-423-5p, miR-219a-2-3p; miR-511-5p, miR-483-5p showed significant (FDR corrected; p < 0.05) differential regulation in the synaptic fraction from dlPFC of MDD subjects. In vitro transfection studies and gene ontology revealed involvement of these altered miRNAs in synaptic plasticity, nervous system development, and neurogenesis. A shift in expression ratios (synaptic vs. total fraction) of miR-19b-3p, miR-376c-3p, miR-455-3p, and miR-337-3p were also noted in the MDD group. Moreover, an inverse relationship between the expression of precursor (pre-miR-19b-1, pre-miR-199a-1 and pre-miR-199a-2) and mature (miR-19b-3p, miR-199a-3p) miRNAs was found. Although not significantly, several miRNA processing enzymes (DROSHA [95%], DICER [17%], TARBP2 [38%]) showed increased expression patterns in MDD subjects. Our findings provide new insights into the understanding of the regulation of miRNAs at the synapse and their possible roles in MDD pathogenesis.Subject terms: Depression, Depression     

Angiotensin II type 1 receptor signalling regulates microRNA differentially in cardiac fibroblasts and myocytes

BACKGROUND AND PURPOSE

The angiotensin II type 1 receptor (AT₁R) is a key regulator of blood pressure and cardiac contractility and is profoundly involved in development of cardiac disease. Since several microRNAs (miRNAs) have been implicated in cardiac disease, we determined whether miRNAs might be regulated by AT₁R signals in a Gαq/11-dependent or -independent manner.

EXPERIMENTAL APPROACH

We performed a global miRNA array analysis of angiotensin II (Ang II)-mediated miRNA regulation in HEK293N cells overexpressing the AT₁R and focused on separating the role of Gαq/11-dependent and -independent pathways. MiRNA regulation was verified with quantitative PCR in both HEK293N cells and primary cardiac myocytes and fibroblasts.

KEY RESULTS

Our studies revealed five miRNAs (miR-29b, -129-3p, -132, -132* and -212) that were up-regulated by Ang II in HEK293N cells. In contrast, the biased Ang II analogue, [Sar1, Ile4, Ile8] Ang II (SII Ang II), which selectively activates Gαq/11-independent signalling, failed to regulate miRNAs in HEK293N cells. Furthermore, Ang II-induced miRNA regulation was blocked following Gαq/11 and Mek1 inhibition. The observed Ang II regulation of miRNA was confirmed in primary cultures of adult cardiac fibroblasts. Interestingly, Ang II did not regulate miRNA expression in cardiac myocytes, but SII Ang II significantly down-regulated miR-129-3p.

CONCLUSIONS AND IMPLICATIONS

Five miRNAs were regulated by Ang II through mechanisms depending on Gαq/11 and Erk1/2 activation. These miRNAs may be involved in Ang II-mediated cardiac biology and disease, as several of these miRNAs have previously been associated with cardiovascular disease and were found to be regulated in cardiac cells.     

MiR-199a-5p and miR-375 affect colon cancer cell sensitivity to cetuximab by targeting PHLPP1

Objectives: We aimed to analyze the differentially-expressed miRNAs in colon cancer cells in order to identify novel potential biomarkers involved in cancer cell resistance.

Design and methods: We investigated the miRNA expression profile of GEO human colon carcinoma cells, sensitive to the EGFR inhibitor Cetuximab (CTX) and their CTX-resistant counterpart (GEO CR) by using a miRNA chip.

Results: We found 27 upregulated and 10 downregulated miRNAs in GEO CR compared with GEO cells with a fold change ≥ 2. Among the upregulated miRNAs, we focused on miR-199a-5p and miR-375. We report that their enforced expression promotes CTX resistance, whereas their silencing sensitizes to the same drug. The ability of miR-199a-5p and miR-375 to target PHLPP1 (PH domain and leucine-rich repeat protein phosphatase 1), a tumor suppressor that negatively regulates the AKT pathway, accounts, at least in part, for their drug-resistance activity. Indeed, restoration of PHLPP1 increases sensitivity of the GEO cells to CTX and reverts the resistance-promoting effect of miR-199a-5p and miR-375.

Conclusion: This study proposes miR-199a-5p and miR-375 as contributors to CTX resistance in colon cancer and suggests a novel approach based on miRNAs as tools for the therapy of this tumor.     

MicroRNA expression profiling involved in MC-LR-induced hepatotoxicity using high-throughput sequencing analysis

Microcystin-LR (MC-LR), the most common microcystin (MC) present in water is known to pose a significant threat to human health especially hepatotoxicity. However, the specific molecular mechanisms underlying MC-LR-induced hepatic cellular damage still remain to be determined. MicroRNAs (miRNAs) are known to play key roles in cellular processes including development, cell proliferation and responsiveness to stress. Thus, this study aimed to examine, whether miRNAs were involved in the observed MC-LR-mediated liver damage using miRNA profiling of a human normal liver cell line HL7702 using high-throughput sequencing techniques. Protein phosphatase 2A (PP2A) activity, an established biomarker of microcystin toxicity, was determined 24 hr following treatment with the algal toxin to confirm responsiveness. Data demonstrated that MC-LR significantly inhibited PP2A activity in a concentration-dependent manner with inhibitory concentration (IC₅₀) value of 4.6 μM. Compared with control cells, treatment with MC-LR at concentrations of 1, 2.5, 5 or 10 μM significantly modified expression of levels of 3, 10, 9, and 99 miRNAs, respectively. Expression levels of miR-15b-3p were significantly increased in all 4 treatment groups, while miR-4521 expression levels were markedly reduced. In the case of miR-451a, 1, 5 or 10 μM also significantly lowered expression levels. However, a significant rise in miR-451a was noted in cells exposed to 2.5 μM toxin. The results obtained from miRNA differential expression levels were confirmed by real-time fluorescent quantitative PCR (qPCR). Gene Ontology (GO) enrichment analysis of hepatic cells demonstrated that miRNAs significantly altered were involved in systems development, metabolism, and protein binding. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis data showed that target genes of differentially expressed miRNAs in liver cells predominantly participated in mechanistic target of rapamycin kinase (mTOR), Ras, Ras-related protein 1 (Rap1), hypoxia inducible factor 1 (HIF-1), and cancer development. In summary, evidence indicates that MC-LR-induced hepatotoxicity may be associated with alterations in miRNAs. Evidence indicates that alterations in miR-451a, miR-4521 and miR-15b-3p may be involved in the observed MC-LR- induced hepatotoxicity     

MicroRNA expression profiling of Chinese follicular lymphoma by microarray: A preliminary study

BackgroundMicroRNAs (miRNAs) have been widely regarded as crucial regulators in various biological processes involved in carcinogenesis. However, the comprehensive miRNA profiles of Chinese follicular lymphoma (FL) remains completely unknown.MethodsThe Exiqon miRCURY LNA™ microRNA Array (v.18.0) was used to detect the miRNA expression profiles of three Chinese FL samples, and compared to three reactive lymphatic nodes (RLN). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to confirm the selected miRNAs in different series. Three databases (miRAnda, miRBase and TargetScan) were used to predict the putative target genes. Bioinformatic analysis (gene ontology analysis and pathway analysis) was performed for further evaluation.ResultsThe microarray assay demonstrated that 1643 miRNAs were expressed; in which 103 miRNAs were upregulated and 68 miRNAs were downregulated, according to P-value (< 0.05) and fold change (FC > 2-fold). Furthermore, qRT-PCR was used to confirm that miR-17-5p, miR-20a-5p and miR-19a-3p were upregulated, and miR-3615 was downregulated (P < 0.05). Bioinformatic analysis (gene ontology analysis and pathway analysis) was used for further evaluation. Pathway analysis indicated that 25 pathways corresponded to differentially expressed miRNAs (P-value cut-off is 0.05). Furthermore, miR-17-5p, miR-20a-5p and miR-19a-3p were validated by qRT-PCR in an independent series including five FL3a and five RLN cases. Data analysis revealed that the changing trend of miR-19a-3p and miR-17-5p expression in the independent series was basically identical with that of the microarray data.ConclusionsOur results are the first to reveal the miRNA expression profiling of Chinese FL and three upregulated miRNAs. Furthermore, the expression of miR-19a-3p and miR-17-5p were found to be significantly upregulated in FL3a. Further study needs to be urgently performed to reveal its potential role in the pathogenesis of FL in the near future.     

Exposure to PM2.5 causes genetic changes in fetal rat cerebral cortex and hippocampus

PM_2.5 travels along the respiratory tract and enters systemic blood circulation. Studies have shown that PM_2.5 increases the incidence of various diseases not only in adults but also in newborn infants. It causes chronic inflammation in pregnant women and retards fetal development. In this study, pregnant rats were exposed to PM_2.5 for extended periods of time and it was found that PM_2.5 exposure increased immune cells in mother rats. In addition, cytokines and free radicals rapidly accumulated in the amniotic fluid and indirectly affected the fetuses. The authors collected cerebral cortex and hippocampus samples at E18 and analyzed changes of miRNA levels. Expression levels of cortical miR‐6315, miR‐3588, and miR‐466b‐5p were upregulated, and positively correlated with the genes Pkn2 (astrocyte migration), Gorab (neuritogenesis), and Mobp (allergic encephalomyelitis). In contrast, PM_2.5 decreased expression of miR‐338‐5p and let‐7e‐5p, both related to mental development. Further, PM_2.5 exposure increased miR‐3560 and let‐7b‐5p in the hippocampus, two proteins that regulate genes Oxct1 and Lin28b that control ketogenesis and glycosylation, and neural cell differentiation, respectively. miR‐99b‐5p, miR‐92b‐5p, and miR‐99a‐5p were decreased, leading to reduced expression of Kbtbd8 and Adam11 which reduced cell mitosis, migration, and differentiation, and inhibited learning abilities and motor coordination of the fetus. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1412–1425, 2017.     

Aberrant expression of miRNA-192-5p contributes to N,N-dimethylformamide-induced hepatic apoptosis

Excessive exposure to N,N-dimethylformamide (DMF) can lead to occupational liver poisoning in workers; however, the underlying mechanism is not fully clarified. The importance of microRNAs (miRNAs) in chemical-induced hepatotoxicity has been demonstrated. To determine whether miRNAs are also involved in DMF-induced hepatotoxicity, we systematically analyzed the miRNA expression profiles in DMF-treated (75 and 150 mm ) HL-7702 liver cells and controls by high-throughput sequencing. Among the altered miRNAs, miR-192-5p was the most significantly upregulated in HL-7702 cells after DMF exposure and was involved in DMF-mediated cell apoptosis. By contrast, suppression of miR-192-5p in HL-7702 cells attenuated the apoptosis induced by DMF. Furthermore, the anti-apoptotic gene (NIN1/RPN12 binding protein 1 homolog [NOB1]) was predicted to be a potential miR-192-5p target according to bioinformatics analysis. The direct interaction between miR-192-5p and NOB1 was confirmed by the dual-luciferase activity assay in HEK293FT cells. Overexpression of miR-192-5p efficiently reduced NOB1 mRNA and protein expression in HL-7702 cells. Alteration in NOB1 expression influenced DMF-induced hepatotoxicity by affecting hepatic apoptosis. In addition, the inverse correlation between miR-192-5p expression levels and NOB1 expression was further confirmed in DMF-exposed mouse liver tissue samples. These observations demonstrated that promotion of apoptosis from the suppression of NOB1 by miR-192-5p overexpression was responsible for the DMF-induced hepatotoxicity. This work provides the molecular mechanism at the miRNA level for hepatic apoptosis induced by DMF.     

Proteomic characteristics of PM2.5 -induced differentially expressed proteins in human renal tubular epithelial cells

Human renal epithelial (HK-2) cells were treated with PM_2.5 (50 μg/mL) from Shenzhen and Taiyuan, proteomics and bioinformatics were used to screen the differentially expressed proteins (DEPs). A total of 577 DEPs were screened after HK-2 cells exposed to Shenzhen PM_2.5, of which 426 were up-regulated and 151 were down-regulated. A total of 1250 DEPs were screened in HK-2 cells after exposure to Taiyuan PM_2.5, of which 488 were up-regulated and 185 were down-regulated. The top 10 proteins with the highest number of nodes were screened using the interaction network map of DEPs. HK-2 cells exposed to Shenzhen PM_2.5 contained CYR61, CTGF, and THBS1 proteins, while HK-2 cells exposed to Taiyuan PM_2.5 contained ALB, FN1, and CYR61 proteins. Additionally, PM_2.5 components were detected, PM_2.5 samples from Shenzhen and Taiyuan induced obvious changes in DEPs expression, the difference in DEPs between the two cities was probably associated with the different PM_2.5 components.     

Treg responses are associated with PM2.5-induced exacerbation of viral myocarditis

Abstract

The adverse cardiovascular events induced by ambient fine particles (PM_2.5) are paid more attention in the world. The current study was conducted to explore the mechanisms of T regulatory cells (Treg) responses in PM_2.5-induced exacerbation of viral myocarditis. The male BALB/c mice were administered an intratracheal (i.t.) instillation of 10?mg/kg b.w. PM_2.5 suspension. Twenty-four hours later, the mice were injected intraperitoneally (i.p.) with 100?μl of coxsackievirus B3 (CVB3) diluted in Eagle's minimal essential medium (EMEM). Seven days after the treatment, serum, splenetic, and cardiac tissues were examined. The results showed that pre-exposure to PM_2.5 aggravated the cardiac inflammation in the CVB3-infected mice along with an increase of Treg cells in the spleen. The mRNA expressions of interleukin-6 (IL-6), TNF-α, transforming growth factor-β (TGF-β), and Foxp3 were up-regulated in the PM_2.5-pretreated mice than that in the CVB3-treated mice. Similar results were found in the sera. In addition, compared with the CVB3-treated mice, the cardiac protein expression of TGF-β increased in the PM_2.5-pretreated mice. These results demonstrated that preexposure to PM_2.5 exacerbated virus-induced myocarditis possibly through the depression of the immune response and increase of inflammation in myocardium through the Treg responses.     

基于miRNAs的知母水提物体外抑制胃癌细胞SGC7901增殖作用机制

目的 从微小核苷酸（miRNAs）的角度研究知母水提物（aqueous extract from Anemarrhenae Rhizoma,ARAE）体外抑制SGC7901细胞增殖的作用机制。方法 采用MTT法检测ARAE对SGC7901细胞增殖的影响;采用流式细胞术检测ARAE对SGC7901细胞凋亡的影响;采用高通量测序法检测细胞中miRNAs的表达丰度差异;采用miranda、mirbase和targetscan 3个数据库信息比对,预测差异miRNAs的靶基因,并通过KEGG分析靶基因的相关功能;采用实时荧光定量PCR法验证主要靶基因的表达变化。结果 ARAE能明显抑制SGC7901细胞的增殖并诱导其凋亡,调节细胞miR-16-5p、miR-20a-5p、miR-26b-5p和miR-15b-5p的表达水平;并提示这些miRNAs所调控的靶基因主要富集于PI3K-Akt、JAK-STAT和MAPK等信号通路。结论 ARAE可能通过调节SGC7901细胞内miRNAs的表达从而抑制SGC7901细胞增殖,并诱导其凋亡。     

Identification of Novel MicroRNA Signatures Linked to Experimental Autoimmune Myasthenia Gravis Pathogenesis: Down-Regulated miR-145 Promotes Pathogenetic Th17 Cell Response

Emerging evidence demonstrates that miRNAs, a new family of key mRNA regulatory molecules, have crucial roles in controlling and modulating immunity. Their contribution to myasthenia gravis (MG), a T cell-dependent, antibody-mediated nervous system autoimmune disease, has not been thoroughly investigated. In the present study, using a highly sensitive microarray-based approach, we identified 11 miRNAs with differential expression between Peripheral Blood Mononuclear Cells (PBMC) from experimental autoimmune MG (EAMG) rats and control rats. miR-145 is one of the most significantly down-regulated miRNAs in PBMC from EAMG rats. Down-regulation of miR-145 expression was confirmed in PBMC and CD4+CD25- T cells (T effector cells) from both EAMG rats and MG patients by real-time PCR. Bioinformatics target prediction identified two crucial immune-related molecules-CD28 and NFATc1, as putative targets of miR-145. Furthermore, miR-145 inhibited CD28 and NFATc1 expression by directly targeting their 3′-UTRs, which was abolished by mutation of the miR-145 and CD28/NFATc1 binding sites. In vitro up-regulation of miR-145 in CD4+ T cells can significantly reduce CD28 protein levels accompanied by decreased proliferative response. In a dendritic cell (DC)-T cell coculture system, overexpression of miR-145 in AChR-specific CD4+ T cells suppresses NFATc1 expression and T Helper 17 cells level. Finally, we observed that administration of lentiviral-miR-145 decreased the severity of ongoing, established EAMG with decreased IL-17 production, and also decreased serum anti-AChR IgG levels. Our studies provide an important new insight into the pathogenesis of EAMG and MG, which may open a new perspective for the development of effective gene therapy for EAMG/MG.     

Hyper-methylated miR-203 dysregulates ABL1 and contributes to the nickel-induced tumorigenesis

Nickel compounds have been found to be carcinogenic based upon epidemiological, animal and cell culture studies. Previous studies suggest that epigenetic mechanisms play a role in Nickel-induced carcinogenesis such as DNA methylation and histone modification. In this study, we investigated the role of microRNAs (miRNAs) in nickel-induced carcinogenesis. The expression of several miRNAs which may function as tumor suppressor genes revealed a strong downregulation of miR-203 in Ni₃S₂-transformed 16HBE cells (NSTCs). Meanwhile, we observed hypermethylation of CpGs in miR-203 promoter and first exon area, and proved that the hyper-methylated miR-203 was involved in the Nickel-induced tumorigenesis. Moreover, we identified that miR-203 may suppress the tumorigenesis at least in part through negatively regulating its target gene ABL1. Our findings indicate that DNA methylation-associated silencing of tumor suppressor miRNAs contributes to the development of Nickel-induced cancer.