Dicer in immune cell development and function

miR-21 Regulates Immune Balance Mediated by Th17/Treg in Peripheral Blood of Septic Rats during the Early Phase through Apoptosis Pathway

Objective

To study the mechanism by which miR-21 regulates the differentiation and function of Th17/Treg cells in sepsis.

Methods

A rat model with sepsis was made by cecal ligation and puncture (CLP). Then, some of the septic rats were transfected with miR-21 mimic or inhibitor by liposome. At 48 hours, lymphocytes and plasma from septic rats were isolated for further experimental detection. The expression of miR-21 in lymphocytes was detected by Polymerase Chain Reaction (PCR); the differentiation of Th17/Treg cells was counted by flow cytometry; lymphocyte apoptosis was observed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay. The caspase-3/9 proteins were tested by Western blot; IL-10 and IL-17 were detected by enzyme-linked immunosorbent assay (ELISA).

Results

Compared with the sepsis group (SP group), the Th17 cells increased significantly, the Treg cells decreased significantly, the apoptosis rate of lymphocytes decreased significantly, the mRNA and proteins of caspase-3/9 decreased significantly, the IL-17 decreased, and the IL-10 increased in the sepsis group transfected with miR-21 (SP + miR-21 mimic group). After transfection of miR-21 inhibitor, the results were almost opposite to those of SP + miR-21 mimic group.

Conclusions

The differentiation and function of Th17/Treg cells were regulated by miR-21 in sepsis through caspase pathway.

DGCR8 deficiency impairs macrophage growth and unleashes the interferon response to mycobacteria

The mycobacterial cell wall glycolipid trehalose-6,6-dimycolate (TDM) activates macrophages through the C-type lectin receptor MINCLE. Regulation of innate immune cells relies on miRNAs, which may be exploited by mycobacteria to survive and replicate in macrophages. Here, we have used macrophages deficient in the microprocessor component DGCR8 to investigate the impact of miRNA on the response to TDM. Deletion of DGCR8 in bone marrow progenitors reduced macrophage yield, but did not block macrophage differentiation. DGCR8-deficient macrophages showed reduced constitutive and TDM-inducible miRNA expression. RNAseq analysis revealed that they accumulated primary miRNA transcripts and displayed a modest type I IFN signature at baseline. Stimulation with TDM in the absence of DGCR8 induced overshooting expression of IFNβ and IFN-induced genes, which was blocked by antibodies to type I IFN. In contrast, signaling and transcriptional responses to recombinant IFNβ were unaltered. Infection with live Mycobacterium bovis Bacille Calmette-Guerin replicated the enhanced IFN response. Together, our results reveal an essential role for DGCR8 in curbing IFNβ expression macrophage reprogramming by mycobacteria.

Widespread transcriptional disruption of the microRNA biogenesis machinery in brain and peripheral tissues of individuals with schizophrenia

In schizophrenia, altered transcription in brain and peripheral tissues may be due to altered expression of the microRNA biogenesis machinery genes. In this study, we explore the expression of these genes both at the cerebral and peripheral levels. We used shinyGEO application to analyze gene expression from ten Gene Expression Omnibus datasets, in order to perform differential expression analyses for eight genes encoding the microRNA biogenesis machinery. First, we compared expression of the candidate genes between control subjects and individuals with schizophrenia in postmortem cerebral samples from seven different brain regions. Then, we compared the expression of the candidate genes between control subjects and individuals with schizophrenia in three peripheral tissues. In brain and peripheral tissues of individuals with schizophrenia, we report distinct altered expression patterns of the microRNA biogenesis machinery genes. In the dorsolateral prefrontal cortex, associative striatum and cerebellum of individuals with schizophrenia, we observed an overexpression pattern of some candidate genes suggesting a heightened miRNA production in these brain regions. Additionally, mixed transcriptional abnormalities were identified in the hippocampus. Moreover, in the blood and olfactory epithelium of individuals with schizophrenia, we observed distinct aberrant transcription patterns of the candidate genes. Remarkably, in individuals with schizophrenia, we report DICER1 overexpression in the dorsolateral prefrontal cortex, hippocampus and cerebellum as well as a congruent DICER1 upregulation in the blood compartment suggesting that it may represent a peripheral marker. Transcriptional disruption of the miRNA biogenesis machinery may contribute to schizophrenia pathogenesis both in brain and peripheral tissues.

The Role of MicroRNAs in Regulatory T Cells

MicroRNAs are a class of conserved, 20 nt-23 nt long, noncoding small RNAs that inhibit expression of their respective target genes in different cell types. Regulatory T cells (Tregs) are a subpopulation of T cells that negatively regulate immune responses, which is essential to immune homeostasis. Recent studies have indicated that microRNAs play an important role in the proliferation, differentiation, and functions of Treg. Here, we review the recent progress in understanding the roles of microRNAs in Treg and their dysregulation in immune-related diseases. This ongoing research continues to expand the understanding of Treg regulation and the mechanisms of immune disorders.

Dietary Lutein Plus Zeaxanthin Intake and DICER1 rs3742330 A > G Polymorphism Relative to Colorectal Cancer Risk

It is unclear whether dietary lutein/zeaxanthin intake in colorectal cancer is associated with microRNA processing involved in DICER1 cleavage for messenger RNA translation. We investigated whether dietary lutein/zeaxanthin intake affects colorectal cancer risk in patients with a DICER1 rs3742330 polymorphism. In this hospital-based case-control study, we recruited 923 colorectal cancer patients and 1,846 controls based on eligibility criteria, a semiquantitative food frequency questionnaire and the DICER1 rs3742330 genotype. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by unconditional logistic regression adjusted for confounders. The highest quartile of lutein/zeaxanthin consumption was inversely associated with a reduced colorectal cancer risk (OR, 95% CI = 0.25, 0.18-0.36). Carrying G allele (AG + GG) showed a significantly reduced colorectal cancer incidence compared with that of AA carriers (OR, 95% CI = 0.71, 0.55-0.91). Those carrying the G allele (AG + GG) along with high lutein/zeaxanthin consumption were markedly associated with a decreased colorectal cancer risk (OR, 95% CI = 0.32, 0.22-0.46, P for interaction = 0.018), particularly for rectal cancer (OR, 95% CI = 0.24, 0.15-0.39, P for interaction = 0.004), compared with that of AA carriers with low lutein/zeaxanthin intakes. In conclusion, colorectal cancer risk was related to an interactive effect between dietary lutein/zeaxanthin intake and the DICER1 rs3742330 polymorphism.

JNK-mediated microglial DICER degradation potentiates inflammatory responses to induce dopaminergic neuron loss

Background

Amplified inflammation is important for the progression of Parkinson’s disease (PD). However, how this enhanced inflammation is regulated remains largely unknown. Deletion of DICER leads to progressive dopamine neuronal loss and induces gliosis. We hypothesized that the homeostasis of microglial DICER would be responsible for the amplified inflammation in the mouse model of PD.

Methods

The microglia or C57BL/6 mice were treated or injected with l-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP) or 1-methyl-4-phenylpyridinium (MPP⁺), respectively, for the model establishment. Microglia and astrocytes sorted by fluorescence-activated cell sorter (FACS) were assayed by quantitative real-time PCR, Western blotting, immunoprecipitation, enzyme-linked immunosorbent assay (ELISA), immunohistofluorescence, and mass spectrometry.

Results

Microglial DICER was phosphorylated at serine 1456 by c-jun N-terminal kinase (JNK) and downregulated in response to 1-methyl-4-phenylpyridinium (MPP⁺), a causative agent in PD. Inhibition of JNK phosphorylation of DICER at serine 1456 rescued the MPP⁺-induced DICER degradation, suppressed microglial inflammatory process, and prevented the loss of tyrosine hydroxylase-expressing neurons in the mouse MPTP model.

Conclusions

JNK-mediated microglial DICER degradation potentiates inflammation to induce dopaminergic neuronal loss. Thus, preventing microglial DICER degradation could be a novel strategy for controlling neuroinflammation in PD.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1218-1) contains supplementary material, which is available to authorized users.

MicroRNAs in neutrophils: potential next generation therapeutics for inflammatory ailments

Neutrophils play fundamental roles in both acute and chronic inflammatory conditions, and directly contribute to the immune pathologies in both infectious and autoimmune ailments. MicroRNAs (miRs) regulate homeostasis in health and disease by fine tuning the expression of a network of genes through post-transcriptional regulation. Many miRs are expressed in restricted tissues, regulated by stress and disease, and are emerging as mediators for intercellular communication. MiR profiles have been recently utilized as biomarkers for diagnosis and prognostic purposes. In addition, several miRs are in clinical development for various diseases. A short list of miRs that regulate hematopoiesis and neutrophil development is identified. Unfortunately, very limited information is available regarding how miRs regulate neutrophil migration and activation in vivo. Extensive future work is required, especially in animal models such as mice, to illustrate the pivotal and complex miR-mediated regulatory network. In addition, zebrafish, a vertebrate model organism with conserved innate immunity, potentiated by the availability of imaging and genetic tools, will provide a platform for rapid discovery and characterization of miRs that are relevant to neutrophilic inflammation. Advances in this field are expected to provide the foundation for highly selective miR-based therapy to manipulate neutrophils in infection and inflammatory disorders.

The epigenetic regulation of Dicer and microRNA biogenesis by Panobinostat

microRNAs (miRs) are small noncoding RNAs that regulate/fine tune many cellular protein networks by targeting mRNAs for either degradation or translational inhibition. Dicer, a type III endoribonuclease, is a critical component in miR biogenesis and is required for mature microRNA production. Abnormal Dicer expression occurs in numerous cancer types and correlates with poor patient prognosis. Recent reports have demonstrated that epigenetic agents, including histone deacetylase inhibitors (HDACi), may regulate Dicer and miR expression. HDACi are a class of epigenetic agents used to treat cancer, viral infections, and inflammatory disorders. However, little is known regarding the epigenetic regulation of miR biogenesis and function. We therefore investigated whether clinically successful HDACi modulated Dicer expression and found that Panobinostat, a clinically approved HDACi, enhanced Dicer expression via posttranscriptional mechanisms. Studies using proteasome inhibitors suggested that Panobinostat regulated the proteasomal degradation of Dicer. Further studies demonstrated that Panobinostat, despite increasing Dicer protein expression, decreased Dicer activity. This suggests that Dicer protein levels do not necessarily correlate with Dicer activity and mature miR levels. Taken together, we present evidence here that Panobinostat posttranscriptionally regulates Dicer/miR biogenesis and suggest Dicer as a potential therapeutic target in cancer.

Role of MicroRNA in the Lung's Innate Immune Response

The immune response to respiratory pathogens must be robust enough to defend the host yet properly constrained such that inflammation-induced tissue damage is avoided. MicroRNA (miRNA) are small noncoding RNA which posttranscriptionally influence gene expression. In this review, we discuss recent experimental evidence of the contribution of miRNA to the lung's response to bacterial and viral pathogens.

MicroRNAs in Type 1 Diabetes: Complex Interregulation of the Immune System, β Cell Function and Viral Infections

Since the discovery of the first mammalian microRNA (miRNA) more than two decades ago, a plethora of miRNAs has been identified in humans, now amounting to more than 2500. Essential for post-transcriptional regulation of gene networks integral for developmental pathways and immune response, it is not surprising that dysregulation of miRNAs is often associated with the aetiology of complex diseases including cancer, diabetes and autoimmune disorders. Despite massive expansion of small RNA studies and extensive investigation in diverse disease contexts, the role of miRNAs in type 1 diabetes has only recently been explored. Key studies using human islets have recently implicated virus-induced miRNA dysregulation as a pivotal mechanism of β cell destruction, while the interplay between miRNAs, the immune system and β cell survival has been illustrated in studies using animal and cellular models of disease. The role of specific miRNAs as major players in immune system homeostasis highlights their exciting potential as therapeutics and prognostic biomarkers of type 1 diabetes.

Gene expression alterations related to mania and psychosis in peripheral blood of patients with a first episode of psychosis

Psychotic disorders affect ~3% of the general population and are among the most severe forms of mental diseases. In early stages of psychosis, clinical aspects may be difficult to distinguish from one another. Undifferentiated psychopathology at the first-episode of psychosis (FEP) highlights the need for biomarkers that can improve and refine differential diagnosis. We investigated gene expression differences between patients with FEP-schizophrenia spectrum (SCZ; N=53) or FEP-Mania (BD; N=16) and healthy controls (N=73). We also verified whether gene expression was correlated to severity of psychotic, manic, depressive symptoms and/or functional impairment. All participants were antipsychotic-naive. After the psychiatric interview, blood samples were collected and the expression of 12 psychotic-disorder-related genes was evaluated by quantitative PCR. AKT1 and DICER1 expression levels were higher in BD patients compared with that in SCZ patients and healthy controls, suggesting that expression of these genes is associated more specifically to manic features. Furthermore, MBP and NDEL1 expression levels were higher in SCZ and BD patients than in healthy controls, indicating that these genes are psychosis related (independent of diagnosis). No correlation was found between gene expression and severity of symptoms or functional impairment. Our findings suggest that genes related to neurodevelopment are altered in psychotic disorders, and some might support the differential diagnosis between schizophrenia and bipolar disorder, with a potential impact on the treatment of these disorders.

The modulation of Dicer regulates tumor immunogenicity in melanoma

MicroRNAs (miRs) are small non-coding RNAs that regulate most cellular protein networks by targeting mRNAs for translational inhibition or degradation. Dicer, a type III endoribonuclease, is a critical component in microRNA biogenesis and is required for mature microRNA production. Abnormal Dicer expression occurs in numerous cancer types and correlates with poor patient prognosis. For example, increased Dicer expression in melanoma is associated with more aggressive tumors (higher tumor mitotic index and depth of invasion) and poor patient prognosis. However, the role that Dicer plays in melanoma development and immune evasion remains unclear. Here, we report on a newly discovered relationship between Dicer expression and tumor immunogenicity. To investigate Dicer's role in regulating melanoma immunogenicity, Dicer knockdown studies were performed. We found that B16F0-Dicer deficient cells exhibited decreased tumor growth compared to control cells and were capable of inducing anti-tumor immunity. The decrease in tumor growth was abrogated in immunodeficient NSG mice and was shown to be dependent upon CD8⁺ T cells. Dicer knockdown also induced a more responsive immune gene profile in melanoma cells. Further studies demonstrated that CD8⁺ T cells preferentially killed Dicer knockdown tumor cells compared to control cells. Taken together, we present evidence which links Dicer expression to tumor immunogenicity in melanoma.

Dicer Is Down-regulated and Correlated with Drosha in Idiopathic Sudden Sensorineural Hearing Loss

Previously, we reported the expression levels of specific microRNA machinery components, DGCR8 and AGO2, and their clinical association in patients with idiopathic sudden hearing loss (SSNHL). In the present study, we investigated the other important components of microRNA machinery and their association with clinical parameters in SSNHL patients. Fifty-seven patients diagnosed with SSNHL and fifty healthy volunteers were included in this study. We evaluated mRNA expression levels of Dicer and Drosha in whole blood of patients with SSNHL and the control group, using RT & real-time PCR analysis. The Dicer mRNA expression level was down-regulated in patients with SSNHL. However, the Drosha mRNA expression level was not significantly altered in patients with SSNHL. Neither the Dicer nor Drosha mRNA expression level was not associated with any clinical parameters, including age, sex, duration of initial treatment from onset (days), initial Pure tone average, Siegel's criteria, WBC, and Erythrocyte sedimentation rate. However, mRNA expression levels of Dicer and Drosha were positively correlated to each other in patients with SSNHL. In this study, we demonstrated for the first time that the Dicer mRNA expression level was down-regulated in patients with SSNHL, suggesting its important role in pathobiology of SSNHL development.

Global microRNA expression is essential for murine mast cell development in vivo

MicroRNAs (miRNAs) are small, noncoding RNAs that have been shown to play a critical role in normal physiology and disease, such as hematopoietic development and cancer. However, their role in mast-cell function and development is poorly understood. The major objective of this study was to determine how global miRNA expression affects mast-cell physiology. The RNase III endonuclease, Dicer, is required for the processing of pre-miRNAs into mature miRNAs. To investigate the effect of global miRNA depletion on mast cells in vivo, we generated a mast-cell-specific knock out of Dicer in mice. Transgenic mice (Mcpt5-Cre) that express Cre selectively in connective tissue mast cells were crossed with mice carrying the floxed conditional Dicer allele (Dicer fl/fl). Mcpt5-Cre × Dicer fl/fl mice with homozygous Dicer gene deletion in mast cells were found to have a profound mast-cell deficiency with near complete loss of peritoneal, gastrointestinal, and skin mast cells. We examined the in vivo functional consequence of mast-cell-specific Dicer deletion using an immunoglobulin-E-dependent passive systemic anaphylaxis murine model. Immunoglobulin-E-sensitized wild type Mcpt5-Cre × Dicer +/+ and heterozygous Mcpt5-Cre × Dicer fl/+ mice show marked hypothermia with antigen; however, homozygous Mcpt5-Cre × Dicer fl/fl mice were completely unresponsive to antigen challenge. These studies suggest a critical role for Dicer and miRNA expression for establishment of tissue compartments of functional mast cells in vivo.