| 1. |
- Bergman, Petra, et al.
(författare)
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Next-generation sequencing identifies microRNAs that associate with pathogenic autoimmune neuroinflammation in rats.
- 2013
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 190:8, s. 4066-75
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Tidskriftsartikel (refereegranskat)abstract
- MicroRNAs (miRNAs) are known to regulate most biological processes and have been found dysregulated in a variety of diseases, including multiple sclerosis (MS). In this study, we characterized miRNAs that associate with susceptibility to develop experimental autoimmune encephalomyelitis (EAE) in rats, a well-established animal model of MS. Using Illumina next-generation sequencing, we detected 544 miRNAs in the lymph nodes of EAE-susceptible Dark Agouti and EAE-resistant Piebald Virol Glaxo rats during immune activation. Forty-three miRNAs were found differentially expressed between the two strains, with 81% (35 out of 43) showing higher expression in the susceptible strain. Only 33% of tested miRNAs displayed differential expression in naive lymph nodes, suggesting that a majority of regulated miRNAs are EAE dependent. Further investigation of a selected six miRNAs indicates differences in cellular source and kinetics of expression. Several of the miRNAs, including miR-146a, miR-21, miR-181a, miR-223, and let-7, have previously been implicated in immune system regulation. Moreover, 77% (33 out of 43) of the miRNAs were associated with MS and other autoimmune diseases. Target genes likely regulated by the miRNAs were identified using computational predictions combined with whole-genome expression data. Differentially expressed miRNAs and their targets involve functions important for MS and EAE, such as immune cell migration through targeting genes like Cxcr3 and cellular maintenance and signaling by regulation of Prkcd and Stat1. In addition, we demonstrated that these three genes are direct targets of miR-181a. Our study highlights the impact of multiple miRNAs, displaying diverse kinetics and cellular sources, on development of pathogenic autoimmune inflammation.
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| 2. |
- Fekete, Tünde, et al.
(författare)
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Constraints for monocyte-derived dendritic cell functions under inflammatory conditions.
- 2012
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Ingår i: European Journal of Immunology. - : Wiley. - 0014-2980 .- 1521-4141. ; 42:2, s. 458-69
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Tidskriftsartikel (refereegranskat)abstract
- The activation of TLRs expressed by macrophages or DCs, in the long run, leads to persistently impaired functionality. TLR signals activate a wide range of negative feedback mechanisms; it is not known, however, which of these can lead to long-lasting tolerance for further stimulatory signals. In addition, it is not yet understood how the functionality of monocyte-derived DCs (MoDCs) is influenced in inflamed tissues by the continuous presence of stimulatory signals during their differentiation. Here we studied the role of a wide range of DC-inhibitory mechanisms in a simple and robust model of MoDC inactivation induced by early TLR signals during differentiation. We show that the activation-induced suppressor of cytokine signaling 1 (SOCS1), IL-10, STAT3, miR146a and CD150 (SLAM) molecules possessed short-term inhibitory effects on cytokine production but did not induce persistent DC inactivation. On the contrary, the LPS-induced IRAK-1 downregulation could alone lead to persistent MoDC inactivation. Studying cellular functions in line with the activation-induced negative feedback mechanisms, we show that early activation of developing MoDCs allowed only a transient cytokine production that was followed by the downregulation of effector functions and the preservation of a tissue-resident non-migratory phenotype.
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| 3. |
- Gastaldi, Cécile, et al.
(författare)
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miR-193b/365a cluster controls progression of epidermal squamous cell carcinoma.
- 2014
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 35:5, s. 1110-20
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Tidskriftsartikel (refereegranskat)abstract
- Incidence of cutaneous squamous cell carcinomas (cSCCs) constantly increases in the Caucasian population. Developing preferentially on precancerous lesions such as actinic keratoses due to chronic sunlight exposure, cSCCs result from the malignant transformation of keratinocytes. Although a resection of the primary tumor is usually curative, a subset of aggressive cSCCs shows a high risk of recurrence and metastases. The characterization of the molecular dysfunctions involved in cSCC development should help to identify new relevant targets against these aggressive cSCCs. In that context, we have used small RNA sequencing to identify 100 microRNAs (miRNAs) whose expression was altered during chemically induced mouse skin tumorigenesis. The decreased expression of the miR-193b/365a cluster during tumor progression suggests a tumor suppressor role. Ectopic expression of these miRNAs in tumor cells indeed inhibited their proliferation, clonogenic potential and migration, which were stimulated in normal keratinocytes when these miRNAs were blocked with antisense oligonucleotides. A combination of in silico predictions and transcriptome analyses identified several target genes of interest. We validated KRAS and MAX as direct targets of miR-193b and miR-365a. Repression of these targets using siRNAs mimicked the effects of miR-193b and miR-365a, suggesting that these genes might mediate, at least in part, the tumor-suppressive action of these miRNAs.
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| 4. |
- Lovén, Jakob, et al.
(författare)
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MYCN-regulated microRNAs repress estrogen receptor-alpha (ESR1) expression and neuronal differentiation in human neuroblastoma.
- 2010
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 107:4, s. 1553-8
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Tidskriftsartikel (refereegranskat)abstract
- MYCN, a proto-oncogene normally expressed in the migrating neural crest, is in its amplified state a key factor in the genesis of human neuroblastoma (NB). However, the mechanisms underlying MYCN-mediated NB progression are poorly understood. Here, we present a MYCN-induced miRNA signature in human NB involving the activation and transrepression of several miRNA genes from paralogous clusters. Several family members derived from the miR-17 approximately 92 cluster, including miR-18a and miR-19a, were among the up-regulated miRNAs. Expression analysis of these miRNAs in NB tumors confirmed increased levels in MYCN-amplified samples. Specifically, we show that miR-18a and miR-19a target and repress the expression of estrogen receptor-alpha (ESR1), a ligand-inducible transcription factor implicated in neuronal differentiation. Immunohistochemical staining demonstrated ESR1 expression in human fetal sympathetic ganglia, suggesting a role for ESR1 during sympathetic nervous system development. Concordantly, lentiviral restoration of ESR1 in NB cells resulted in growth arrest and neuronal differentiation. Moreover, lentiviral-mediated inhibition of miR-18a in NB cells led to severe growth retardation, outgrowth of varicosity-containing neurites, and induction of neuronal sympathetic differentiation markers. Bioinformatic analyses of microarray data from NB tumors revealed that high ESR1 expression correlates with increased event-free survival in NB patients and favorable disease outcome. Thus, MYCN amplification may disrupt estrogen signaling sensitivity in primitive sympathetic cells through deregulation of ESR1, thereby preventing the normal induction of neuroblast differentiation. Collectively, our findings demonstrate the molecular consequences of abnormal miRNA transcription in a MYCN-driven tumor and offer unique insights into the pathology underlying MYCN-amplified NB.
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| 5. |
- Meisgen, Florian, et al.
(författare)
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Activation of toll-like receptors alters the microRNA expression profile of keratinocytes.
- 2014
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Ingår i: Experimental dermatology. - : Wiley. - 0906-6705 .- 1600-0625. ; 23:4, s. 281-3
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Tidskriftsartikel (refereegranskat)abstract
- Keratinocytes recognize invading pathogens by various receptors, among them Toll-like receptors (TLRs), and provide the first line of defense in skin immunity. The role of microRNAs in this important defense mechanism has not been explored yet. Our aim was to identify microRNAs involved in the innate immune response of keratinocytes. MicroRNA expression profiling revealed that the TLR2 ligand zymosan, the TLR3 ligand poly(I:C) or the TLR5 ligand flagellin significantly altered the microRNA expression in keratinocytes. The regulation of microRNAs was concentration-dependent and it could be neutralized by siRNAs specific for TLR2, TLR3 and TLR5, respectively, confirming the specificity of the TLR response. Interestingly, one microRNA, miR-146a, was strongly induced by all studied TLR ligands, while other microRNAs were regulated in a TLR- or time point-specific manner. These findings suggest an important role for microRNAs in the innate immune response of keratinocytes and provide a basis for further investigations.
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| 6. |
- Meisgen, Florian, et al.
(författare)
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MiR-146a negatively regulates TLR2-induced inflammatory responses in keratinocytes.
- 2014
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Ingår i: Journal of Investigative Dermatology. - : Elsevier BV. - 0022-202X .- 1523-1747. ; 134:7, s. 1931-1940
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Tidskriftsartikel (refereegranskat)abstract
- Keratinocytes represent the first line of defense against pathogens in the skin and have important roles in initiating and regulating inflammation during infection and autoimmunity. Here we investigated the role of miR-146a in the regulation of the innate immune response of keratinocytes. Toll-like receptor 2 (TLR2) stimulation of primary human keratinocytes resulted in an NF-κB- and mitogen-activated protein kinase-dependent upregulation of miR-146a expression, which was surprisingly long lasting, contrasting with the rapid and transient induction of inflammatory mediators. Overexpression of miR-146a significantly suppressed the production of IL-8, CCL20, and tumor necrosis factor-α, which functionally suppressed the chemotactic attraction of neutrophils by keratinocytes. Inhibition of endogenous miR-146a induced the production of inflammatory mediators even in nonstimulated keratinocytes, and potentiated the effect of TLR2 stimulation. Transcriptomic profiling revealed that miR-146a suppresses the expression of a large number of immune-related genes in keratinocytes. MiR-146a downregulated interleukin-1 receptor-associated kinase 1 and TNF receptor-associated factor 6, two key adapter molecules downstream of TLR signaling, and suppressed NF-κB promoter-binding activity as shown by promoter luciferase experiments. Together, these data identify miR-146a as a regulatory element in keratinocyte innate immunity, which prevents the production of inflammatory mediators under homeostatic conditions and serves as a potent negative feedback regulator after TLR2 stimulation.
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| 7. |
- Meisgen, Florian, et al.
(författare)
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MiR-21 is up-regulated in psoriasis and suppresses T cell apoptosis.
- 2012
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Ingår i: Experimental dermatology. - : Wiley. - 0906-6705 .- 1600-0625. ; 21:4, s. 312-4
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Tidskriftsartikel (refereegranskat)abstract
- MicroRNAs are short non-coding RNAs that regulate gene expression. Previously, in a genome-wide screen, we found deregulation of microRNA expression in psoriasis skin. MicroRNA-21 (miR-21) is one of the microRNAs significantly up-regulated in psoriasis skin lesions. To identify the cell type responsible for the increased miR-21 level, we compared expression of miR-21 in epidermal cells and dermal T cells between psoriasis and healthy skin and found elevated levels of miR-21 in psoriasis in both cell types. In cultured T cells, expression of miR-21 increased markedly upon activation. To explore the function of miR-21 in primary human T helper cells, we inhibited miR-21 using a tiny seed-targeting LNA-anti-miR. Specific inhibition of miR-21 increased the apoptosis rate of activated T cells. Our results suggest that miR-21 suppresses apoptosis in activated T cells, and thus, overexpression of miR-21 may contribute to T cell-derived psoriatic skin inflammation.
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| 8. |
- Pivarcsi, Andor, et al.
(författare)
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Genetic polymorphisms altering microRNA activity in psoriasis--a key to solve the puzzle of missing heritability?
- 2014
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Ingår i: Experimental dermatology. - : Wiley. - 0906-6705 .- 1600-0625. ; 23:9, s. 620-4
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Tidskriftsartikel (refereegranskat)abstract
- Psoriasis is a chronic immune-mediated skin disease in which the balance in the interplay of immune cells and keratinocytes is disturbed. MicroRNAs (miRNAs) are endogenous small regulatory RNAs that stabilize cellular phenotypes and fine-tune signal transduction feedback loops through the regulation of gene networks. Through the regulation of their multiple target genes, miRNAs regulate the development of inflammatory cell subsets and have a significant impact on the magnitude of inflammatory responses. Since the discovery of deregulated miRNA expression in psoriasis, we have learned that they can regulate differentiation, proliferation and cytokine response of keratinocytes, activation and survival of T cells and the crosstalk between immunocytes and keratinocytes through the regulation of chemokine production. In recent years, it became apparent that genetic polymorphisms in miRNA genes and/or in miRNA binding sites of target genes can affect miRNA activity and contribute to disease susceptibility. Psoriasis has a strong genetic background; however, the contribution of genetic variants involving miRNAs is largely unexplored in psoriasis. We propose that changes in miRNA-mediated gene regulation may be a major contributor to the disturbed balance in immune regulation that results in chronic skin inflammation. In this viewpoint essay, we focus on the emerging new aspects of the role of miRNAs in psoriasis and propose that genetic polymorphisms that affect miRNA activity might be important in the pathogenesis of psoriasis.
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| 9. |
- Shimokawa, Takashi, et al.
(författare)
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RNA editing of the GLI1 transcription factor modulates the output of Hedgehog signaling.
- 2013
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Ingår i: RNA Biology. - : Informa UK Limited. - 1547-6286 .- 1555-8584. ; 10:2, s. 321-33
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Tidskriftsartikel (refereegranskat)abstract
- The Hedgehog (HH) signaling pathway has important roles in tumorigenesis and in embryonal patterning. The Glioma-associated oncogene 1 (GLI1) is a key molecule in HH signaling, acting as a transcriptional effector and, moreover, is considered to be a potential therapeutic target for several types of cancer. To extend our previous focus on the implications of alternative splicing for HH signal transduction, we now report on an additional post-transcriptional mechanism with an impact on GLI1 activity, namely RNA editing. The GLI1 mRNA is highly edited at nucleotide 2179 by adenosine deamination in normal cerebellum, but the extent of this modification is reduced in cell lines from the cerebellar tumor medulloblastoma. Additionally, basal cell carcinoma tumor samples exhibit decreased GLI1 editing compared with normal skin. Interestingly, knocking down of either ADAR1 or ADAR2 reduces RNA editing of GLI1. This adenosine to inosine substitution leads to a change from Arginine to Glycine at position 701 that influences not only GLI1 transcriptional activity, but also GLI1-dependent cellular proliferation. Specifically, the edited GLI1, GLI1-701G, has a higher capacity to activate most of the transcriptional targets tested and is less susceptible to inhibition by the negative regulator of HH signaling suppressor of fused. However, the Dyrk1a kinase, implicated in cellular proliferation, is more effective in increasing the transcriptional activity of the non-edited GLI1. Finally, introduction of GLI1-701G into medulloblastoma cells confers a smaller increase in cellular growth relative to GLI1. In conclusion, our findings indicate that RNA editing of GLI1 is a regulatory mechanism that modulates the output of the HH signaling pathway.
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| 10. |
- Sonkoly, Enikö, et al.
(författare)
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MicroRNAs in inflammation and response to injuries induced by environmental pollution.
- 2011
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Ingår i: Mutation research. - : Elsevier BV. - 0027-5107 .- 1873-135X. ; 717:1-2, s. 46-53
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Tidskriftsartikel (refereegranskat)abstract
- MicroRNAs (miRNAs) are small noncoding RNAs that regulate basic biological processes by posttranscriptional suppression of their target genes. Altered miRNA expression may lead to widespread gene expression changes and has been implicated in pathophysiological processes such as cancer and inflammation. In this review, we summarize the present knowledge about the role of miRNAs in inflammation and in the response to environmental agents and pollutants, such as cigarette smoke, ethanol, carcinogenic chemicals such as benzo(a)pyrene (BaP) and dioxin, and UV radiation.
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