Search

Cognitive dysfunction is one of the complications of diabetes. Unfortunately, there is no effective methods to block its progression currently. One of the pathophysiological mechanisms is synaptic protein damage and neuronal signal disruption because of glucose metabolism disorder. Dystroglycan protein, located in the post‐synaptic membrane of neurons, links the intracellular cytoskeleton with extracellular matrix. Abnormal expression of dystroglycan protein affects neuronal biological functions and leads to cognitive impairment. However, there are no relevant studies to observe the changes of β‐dystroglycan protein in diabetes rat brain and in primary neurons under high glucose exposure. Our data demonstrated the alterations of cognitive abilities in the diabetic rats; β‐dystroglycan protein degradation occurred in hippocampal and cortical tissues in diabetic rat brain. We further explored the mechanisms underlying of this phenomenon. When neurons are exposed to high glucose environment in long‐term period, microRNA‐132 (miR‐132) would be down‐regulated in neurons. Matrix Metalloproteinases‐9 (MMP‐9) mRNA, as a target of miR‐132, could be up‐regulated; higher expression and overlay activity of MMP‐9 protein could increase β‐DG protein degradation. In this way, β‐DG degradation may affect structure and functions among the synapses, which related to cognition decline. It may provide some theoretical basis for elucidating the molecular mechanism of diabetes‐induced cognitive dysfunction.

Micro‐RNAs (miRNAs) are highly evolutionarily conserved short‐length/noncoding RNA molecules that modulate a wide range of cellular functions in many cell types by regulating the expression of a variety of targeted genes. miRNAs have also recently emerged as key regulators of neuronal genes mediating the effects of psychostimulant drugs and memory‐related neuroplasticity processes. Smoking is a predominant addictive behaviour associated with millions of deaths worldwide, and nicotine is a potent natural psychoactive agonist of cholinergic receptors, highly abundant in cigarettes. The influence of miRNAs modulation on cholinergic signalling in the nervous system remains however poorly explored. Using miRNA knockout mice and biochemical, electrophysiological and pharmacological approaches, we examined the effects of miR‐132/212 gene disruption on the levels of hippocampal nicotinic acetylcholine receptors, total ERK and phosphorylated ERK (pERK) and MeCP2 protein levels, and studied the impact of nicotine stimulation on hippocampal synaptic transmission and synaptic depression and strengthening. miR‐132/212 deletion significantly altered α7‐nAChR and pERK protein levels, but not total ERK or MeCP2, and resulted in both exacerbated synaptic depression and virtually abolished memory‐related synaptic strengthening upon nicotine stimulation. These observations reveal a functional miRNAs/nicotinergic signalling interplay critical for nicotinic‐receptor expression and neuroplasticity in brain structures relevant for drug addiction and learning and memory functions., Micro‐RNAs are key regulators of neuronal genes mediating the effects of psychostimulant drugs and neuroplasticity. Using miRNA knockout mice and biochemical, electrophysiological and pharmacological approaches, this work describes that miR‐132/212 gene deletion alters molecular elements from the cholinergic signalling pathway (α7‐nAChR and pERK protein levels) and not only exacerbates synaptic depression but also virtually abolishes memory‐related synaptic strengthening upon nicotine stimulation.

Alzheimer's disease (AD) is a kind of neurodegenerative disorder associated with age. Investigations suggest that amyliod-β (Aβ) is implicated in the pathogenesis of AD. The accumulation of Aβ in the brain causes oxidative stress and synaptic toxicity, leads to synaptic dysfunction and neuronal death. Previous investigations suggest that melatonin an endogenous hormone can counteract Aβ-induced neurotoxicity. However, the molecular mechanisms of Aβ-induced toxicity and melatonin treatment remain elusive. Studies indicate that microRNA-132 is crucial for neuronal survival and plays a key role in the pathological process of AD. Moreover, PTEN and FOXO3a two key targets of miR-132 are upregulated in the AD brain. Here, we exposed the primary cultured cortical neurons with Aβ25-35 and treated with melatonin. Our investigations demonstrated that Aβ25-35 exposure significantly decreased the expression of miR-132 and elevated the expression of PTEN and FOXO3a. Whereas, melatonin treatment could rescue the expression of miR-132 and downregulate the level of PTEN and FOXO3a. Moreover, melatonin blocked the nuclear translocation of FOXO3a and thereby suppressed its pro-apoptotic pathways. In addition, our investigations suggested that the over-expression of miR-132 could block Aβ-induced neurotoxicity. We also found that VO-OHpic (PTEN inhibitor) could counteract Aβ-induced neuronal damage, and LY294002 (AKT inhibitor) suppressed the protective effect of melatonin. Together, these results indicate that melatonin exerts its neuroprotective effect in Aβ-induced neurotoxicity via miR-132/PTEN/AKT/FOXO3a pathway. © 2018 BioFactors, 44(6):609-618, 2018.

Cisplatin resistance has long been a major problem that restricts its use. A novel paradigm in tumor biology suggests that gastric tumor chemo-resistance is driven by gastric cancer stem cell-like (GCSCs). Growing evidence has indicated that microRNAs (miRNAs) contributes to chemo-resistance in gastric cancer (GC). Here, Lgr5+ cells derived from gastric cancer cell lines displayed stem cell-like features. Flow cytometry demonstrated the presence of a variable fraction of Lgr5 in 19 out of 20 GC specimens. By comparing the miRNA expression profiles of Lgr5+ GCSCs and Lrg5- cells, we established the upregulation of miR-132 in Lgr5+ GCSCs. The enhanced miR-132 expression correlated chemo-resistance in GC patients. Kaplan-Meier survival curve showed that patients with low miR-132 expression survived obviously longer. Functional assays results indicated that miR-132 promoted cisplatin resistance in Lgr5+ GCSCs in vitro and in vivo. Further dual-luciferase reporter gene assays revealed that SIRT1 was the direct target of miR-132. The expression of miR-132 was inversely correlated with SIRT1 in gastric cancer specimens. Furthermore, through PCR array we discovered ABCG2 was one of the downstream targets of SIRT1. Overexpression of SIRT1 down-regulated ABCG2 expression by promoting the de-acetylation of the transcription factor CREB. CREB was further activated ABCG2 via binding to the promoter of ABCG2 to induce transcription. Thus, we concluded that miR-132 regulated SIRT1/CREB/ABCG2 signaling pathway contributing to the cisplatin resistance and might serve as a novel therapeutic target against gastric cancer.

Background and Aim Although many progresses have been achieved for inflammatory bowel disease (IBD), it is still remained as idiopathic disease to be completely controlled. MicroRNAs (miRNAs) have been identified as key players in many human diseases through degradation or translational inhibition of target genes. Because role of miRNAs in IBD is not completely understood yet, we need to identify miRNAs as novel targets for treatment of IBD. Methods Microarray analysis for miRNAs was performed using dextran sulfate sodium-induced colitis samples and selected differentially regulated miRNAs. Candidate genes were validated using in vitro system and IBD patient samples. Molecular mechanism for regulation of inflammatory signaling was identified using gene modulation system of miRNAs. Results We selected 14 upregulated and 15 downregulated miRNAs through microarray analysis. Among candidate miRNAs, significant upregulation of miR-132 and miR-223 was confirmed in inflamed mouse tissues as well as human IBD patient tissues. Through bioinformatics analysis, we identified FOXO3a as direct target of miRNAs and confirmed regulatory mechanism using luciferase assay. Expression of miRNAs clearly suppressed the level of IκBα through downregulation of FOXO3a, leading to enhanced NF-κB signaling to promote the production of pro-inflammatory cytokines. The downregulation of FOXO3a concurrent with upregulation of cytokines was significantly reversed by sequestration of miRNAs with miRNA sponges. Conclusions Our findings provided the evidences that miR-132 and 223 are critical mediators in positive circuit for pathogenesis of IBD by negatively regulating FOXO3a to enhance the expression of inflammatory cytokines and can be a good therapeutic target for IBD treatment.

Prostate cancer is the second leading cause of cancer-related deaths among men worldwide. Early diagnosis increases survival rates in patients but the survival rate has remained relatively poor over the past years. Increasing evidence shows that altered metabolism is a critical hallmark in prostate cancer. There is a strong need to explore the molecular mechanisms underlying cancer metabolism for prostate cancer therapy. Whether the aberrant expression of microRNA (miRNA) contributes to cancer metabolism is not fully known. In this study, we found that microRNA-132 (miR-132) expression is reduced and thus leads to a metabolic switch in prostate cancer cells. miR-132 performs this role by increasing Glut1 expression, resulting in the enhanced rate of lactate production and glucose uptake. The altered metabolism induced by decreased miR-132 levels confers the rapid growth of the cancer cells. These data indicate that miR-132 is involved in regulating the Warburg effect in prostate cancer by inhibiting Glut1 expression.

MicroRNAs and Yes-associated protein (YAP) play an important role in the occurrence and development of hepatic carcinomas. However, the interaction between microRNAs and YAP was seldom elucidated. In this study, we showed that miR-132 could target YAP gene by using dual-luciferase reporter system. Further quantitative polymerase chain reaction analysis and western blotting showed that miR-132 could significantly reduce the expression of YAP at mRNA and protein levels. Results of annexin V-fluorescein isothiocyanate, 5-ethynyl-2′-deoxyuridine staining and transwell assays showed that miR-132 significantly promoted the cell apoptosis and effectively inhibited the proliferation and invasion of hepatoma cells. These results indicated that miR-132 could inhibit the growth of hepatoma cells by targeting YAP gene and reducing its expression level. Taken together, results from this study would help us to understand the mechanisms for occurrence and development of hepatic carcinoma and provide new targets for diagnosis and treatment of liver cancer. Copyright © 2015 John Wiley & Sons, Ltd.

To assess the involvement of microRNAs (miRNAs) in B-cell receptor (BCR) stimulation, we first evaluated miRNA profiling following IgM cross-linking in chronic lymphocytic leukemia (CLL) cells and in normal B lymphocytes. Second, we combined miRNA and gene expression data to identify putative miRNA functional networks. miRNA profiling showed distinctive patterns of regulation after stimulation in leukemic versus normal B lymphocytes and identified a differential responsiveness to BCR engagement in CLL subgroups according to the immunoglobulin heavy chain variable region mutational status and clinical outcome. The most significantly modulated miRNAs in stimulated CLL are miR-132 and miR-212. Notably, these miRNAs appeared regulated in progressive but not in stable CLL. Accordingly, gene profiling showed a significant transcriptional response to stimulation exclusively in progressive CLL. Based on these findings, we combined miRNA and gene expression data to investigate miR-132 and miR-212 candidate interactions in this CLL subgroup. Correlation analysis pointed to a link between these miRNAs and RB/E2F and TP53 cascades with proproliferative effects, as corroborated by functional analyses. Finally, basal levels of miR-132 and miR-212 were measured in an independent cohort of 20 unstimulated CLL cases and both showed lower expression in progressive compared to stable patients, suggesting an association between the expression of these molecules and disease prognosis. Overall, our results support a model involving miR-132 and miR-212 upregulation in sustaining disease progression in CLL. These miRNAs may therefore provide new valuable strategies for therapeutic intervention. © 2015 Wiley Periodicals, Inc.

MicroRNAs (miRNAs) are a small group of RNAs that are emerging as a new avenue by which autoimmune diseases may be modulated. Accumulating evidence shows that miRNAs are involved in the pathogenesis of MS; however, the interaction of miRNAs with environmentally responsive transcription factors that play prominent roles in MS is unexplored. The activation of aryl hydrocarbon receptor by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alleviates inflammation in experimental autoimmune encephalomyelitis (EAE), the best available model of MS. Therefore, we predicted that TCDD could attenuate EAE by inducing miRNA(s) targeting inflammatory mediators. Here, we show that TCDD induces cholinergic anti-inflammation in EAE mice by upregulating acetylcholinesterase-targeting miR-132. The expression of miR-132 was downregulated in CD4⁺ cells and associated with EAE severity, while TCDD treatment attenuated EAE by inducing the miR-132/acetylcholinesterase module. Silencing miR-132 in vivo abolished TCDD-induced cholinergic anti-inflammation and aggravated EAE. Overexpression of miR-132 in encephalitogenic CD4⁺ cells decreased IL-17 and IFN-γ and suppressed T-cell proliferation. In conclusion, our findings identify a new miRNA-based mechanism through which miR-132 mediates TCDD-induced EAE attenuation, suggesting that miR-132 could be a promising therapeutic target for anti-inflammatory treatment of MS.

MicroRNA-132 (miR-132) has been demonstrated to affect multiple neuronal functions, including dendritic growth and spinogenesis in cultured neurons and brain slices, as well as learning behavior of animals. However, its role in acquisition of temporal-associated memory remains unclear. In this study, we demonstrated that the mature miR-132 level in mouse hippocampus was significantly increased at 30 min after trace fear conditioning, a type of temporal-associated learning, and returned to baseline values in 2 h. We then knocked down miR-132 expression in vivo by infusing a lentivector expressing anti-miR-132 hairpin RNA into the third ventricle near the anterior hippocampi such RNA diffused laterally to both hippocampal formations, later confirmed by histological analysis. This approach successfully reduced hippocampal miR-132 expression in both naive and trace fear conditioned groups, and impaired acquisition of trace fear memory in mice. To our knowledge, this result is the first demonstration of change in temporal learning behavior by reducing microRNA (miRNA) level specifically in the hippocampal region.

The molecular biology and clinical behaviour of gastrointestinal stromal tumours (GISTs) are associated with their anatomical localization (stomach or intestine), and also with the mutation status of the receptor tyrosine kinases KIT and PDGFRA. Twelve GISTs were evaluated for differential miRNA expression signatures by use of microarrays representing 734 human miRNAs. Thirty-two miRNAs were found to be differentially expressed according to localization and mutation status. Differential expression was further analysed and confirmed for four miRNAs (miR-132, miR-221, miR-222, and miR-504) by qRT-PCR in 49 additional GISTs. Differentially expressed miRNAs were functionally mapped to KIT/PDGFRA signalling and G1/S-phase transition of the cell cycle, revealing 22 predicted miRNA/mRNA interactions for ten gene targets from KIT/PDGFRA signalling, and 12 interactions for 12 gene targets of G1/S-phase transition. Moreover, the expression of 44 miRNAs clustered in a genetically imprinted region at 14q32.31 was found to be strongly correlated in the microarray analysis. This was confirmed for two selected miRNAs (miR-134 and miR-370) from the 14q32.31 cluster by qRT-PCR in 49 additional GISTs, and the expression of these two miRNAs was significantly lower in GISTs with 14q loss, and also in GISTs with tumour progress. miRNA profiling may prove to be a key determinant of the biology and clinical features of GISTs.

Activity-dependent changes in gene-expression are believed to underlie the molecular representation of memory. In this study, we report that in vivo activation of neurons rapidly induces the CREB-regulated microRNA miR-132. To determine if production of miR-132 is regulated by neuronal activity its expression in mouse brain was monitored by quantitative RT-PCR (RT-qPCR). Pilocarpine-induced seizures led to a robust, rapid, and transient increase in the primary transcript of miR-132 (pri-miR-132) followed by a subsequent rise in mature microRNA (miR-132). Activation of neurons in the hippocampus, olfactory bulb, and striatum by contextual fear conditioning, odor-exposure, and cocaine-injection, respectively, also increased pri-miR-132. Induction kinetics of pri-miR-132 were monitored and found to parallel those of immediate early genes, peaking at 45 minutes and returning to basal levels within two hours of stimulation. Expression levels of primary and mature-miR-132 increased significantly between postnatal days 10 and 24. We conclude that miR-132 is an activity-dependent microRNA in vivo, and may contribute to the long-lasting proteomic changes required for experience-dependent neuronal plasticity.