Up-regulation of brain-enriched miR-107 promotes excitatory neurotoxicity through down-regulation of glutamate transporter-1 expression following ischaemic stroke

Non-coding RNAs in acute ischemic stroke: from brain to periphery

Acute ischemic stroke is a clinical emergency and a condition with high morbidity, mortality, and disability. Accurate predictive, diagnostic, and prognostic biomarkers and effective therapeutic targets for acute ischemic stroke remain undetermined. With innovations in high-throughput gene sequencing analysis, many aberrantly expressed non-coding RNAs (ncRNAs) in the brain and peripheral blood after acute ischemic stroke have been found in clinical samples and experimental models. Differentially expressed ncRNAs in the post-stroke brain were demonstrated to play vital roles in pathological processes, leading to neuroprotection or deterioration, thus ncRNAs can serve as therapeutic targets in acute ischemic stroke. Moreover, distinctly expressed ncRNAs in the peripheral blood can be used as biomarkers for acute ischemic stroke prediction, diagnosis, and prognosis. In particular, ncRNAs in peripheral immune cells were recently shown to be involved in the peripheral and brain immune response after acute ischemic stroke. In this review, we consolidate the latest progress of research into the roles of ncRNAs (microRNAs, long ncRNAs, and circular RNAs) in the pathological processes of acute ischemic stroke-induced brain damage, as well as the potential of these ncRNAs to act as biomarkers for acute ischemic stroke prediction, diagnosis, and prognosis. Findings from this review will provide novel ideas for the clinical application of ncRNAs in acute ischemic stroke.

Considering Context-Specific microRNAs in Ischemic Stroke with Three "W": Where, When, and What

MicroRNAs are short non-coding RNA molecules that function as critical regulators of various biological processes through negative regulation of gene expression post-transcriptionally. Recent studies have indicated that microRNAs are potential biomarkers for ischemic stroke. In this review, we first illustrate the pathogenesis of ischemic stroke and demonstrate the biogenesis and transportation of microRNAs from cells. We then discuss several promising microRNA biomarkers in ischemic stroke in a context-specific manner from three dimensions: biofluids selection for microRNA extraction (Where), the timing of sample collection after ischemic stroke onset (When), and the clinical application of the differential-expressed microRNAs during stroke pathophysiology (What). We show that microRNAs have the utilities in ischemic stroke diagnosis, risk stratification, subtype classification, prognosis prediction, and treatment response monitoring. However, there are also obstacles in microRNA biomarker research, and this review will discuss the possible ways to improve microRNA biomarkers. Overall, microRNAs have the potential to assist clinical treatment, and developing microRNA panels for clinical application is worthwhile.

Expansion of plasma MicroRNAs over the first month following human stroke

Few have characterized miRNA expression during the transition from injury to neural repair and secondary neurodegeneration following stroke in humans. We compared expression of 754 miRNAs from plasma samples collected 5, 15, and 30 days post-ischemic stroke from a discovery cohort (n = 55) and 15-days post-ischemic stroke from a validation cohort (n = 48) to healthy control samples (n = 55 and 48 respectively) matched for age, sex, race and cardiovascular comorbidities using qRT-PCR. Eight miRNAs remained significantly altered across all time points in both cohorts including many described in acute stroke. The number of significantly dysregulated miRNAs more than doubled from post-stroke day 5 (19 miRNAs) to days 15 (50 miRNAs) and 30 (57 miRNAs). Twelve brain-enriched miRNAs were significantly altered at one or more time points (decreased expression, stroke versus controls: miR-107; increased expression: miR-99-5p, miR-127-3p, miR-128-3p, miR-181a-3p, miR-181a-5p, miR-382-5p, miR-433-3p, miR-491-5p, miR-495-3p, miR-874-3p, and miR-941). Many brain-enriched miRNAs were associated with apoptosis over the first month post-stroke whereas other miRNAs suggested a transition to synapse regulation and neuronal protection by day 30. These findings suggest that a program of decreased cellular proliferation may last at least 30 days post-stroke, and points to specific miRNAs that could contribute to neural repair in humans.

Epigenetic regulation of neurotransmitter signaling in neurological disorders

Neurotransmission signaling is a highly conserved system attributed to various regulatory events. The excitatory and inhibitory neurotransmitter systems have been extensively studied, and their role in neuronal cell proliferation, synaptogenesis and dendrite formation in the adult brain is well established. Recent research has shown that epigenetic regulation plays a crucial role in mediating the expression of key genes associated with neurotransmitter pathways, including neurotransmitter receptor and transporter genes. The dysregulation of these genes has been linked to a range of neurological disorders such as attention-deficit/hyperactivity disorder, Parkinson's disease and schizophrenia. This article focuses on epigenetic regulatory mechanisms that control the expression of genes associated with four major chemical carriers in the brain: dopamine (DA), Gamma-aminobutyric acid (GABA), glutamate and serotonin. Additionally, we explore how aberrant epigenetic regulation of these genes can contribute to the pathogenesis of relevant neurological disorders. By targeting the epigenetic mechanisms that control neurotransmitter gene expression, there is a promising opportunity to advance the development of more effective treatments for neurological disorders with the potential to significantly improve the quality of life of individuals impacted by these conditions.

lncfos/miR-212-5p/CASP7 Axis-Regulated miR-212-5p Protects the Brain Against Ischemic Damage

miR-212-5p has been reported to be involved in many biological processes. However, the role of miR-212-5p in ischemic stroke remains unclear. This study explored the biological role and potential mechanism of miR-212-5p in ischemic stroke by investigating the lncfos/miR-212-5p/CASP7 axis. A total of 32 patients with ischemic stroke and 32 age- and sex-matched healthy controls (HCs) were enrolled in this study. In addition, 336 rats were used in this study. The rats were subjected to middle cerebral artery occlusion (MCAO) and intracerebroventricular injection of a microRNA (miRNA) agomir, a miRNA antagomir, a short hairpin RNA (shRNA) lentiviral vector, or a negative control. The neurological deficit score was calculated; the infarct volume was measured; histopathological assays were performed; the neuronal apoptosis rate was determined; and the lncfos, miR-212-5p, and CASP7 expression levels in the peri-infarct area were assessed. In this study, we found that the expression level of miR-212-5p was significantly downregulated in the peri-infarct area and blood of the MCAO model rats and the blood of patients with ischemic stroke. A double-luciferase experiment showed that CASP7 was a direct target gene of miR-212-5p and that miR-212-5p was a target miRNA of lncfos. Lateral ventricular injection of the miR-212-5p agomir effectively inhibited the apoptosis induced by ischemic brain damage, reduced the infarct volume, attenuated the neurological deficit symptoms, and downregulated the expression of CASP7 in the peri-infarct area of the MCAO model rats. Suppressing lncfos with sh-fos led to the upregulated expression of miR-212-5p and played a neuroprotective role in the rat MCAO models. We concluded that miR-212-5p plays a neuroprotective role in ischemic stroke and that its function is regulated by the lncfos/miR-212-5p/CASP7 axis. Moreover, miR-212-5p may be a potential biomarker and therapeutic target for ischemic stroke.

MicroRNA-mediated regulation of reactive astrocytes in central nervous system diseases

Astrocytes (AST) are abundant glial cells in the human brain, accounting for approximately 20-50% percent of mammalian central nervous system (CNS) cells. They display essential functions necessary to sustain the physiological processes of the CNS, including maintaining neuronal structure, forming the blood-brain barrier, coordinating neuronal metabolism, maintaining the extracellular environment, regulating cerebral blood flow, stabilizing intercellular communication, participating in neurotransmitter synthesis, and defending against oxidative stress et al. During the pathological development of brain tumors, stroke, spinal cord injury (SCI), neurodegenerative diseases, and other neurological disorders, astrocytes undergo a series of highly heterogeneous changes, which are called reactive astrocytes, and mediate the corresponding pathophysiological process. However, the pathophysiological mechanisms of reactive astrocytes and their therapeutic relevance remain unclear. The microRNAs (miRNAs) are essential for cell differentiation, proliferation, and survival, which play a crucial role in the pathophysiological development of CNS diseases. In this review, we summarize the regulatory mechanism of miRNAs on reactive astrocytes in CNS diseases, which might provide a theoretical basis for the diagnosis and treatment of CNS diseases.

The role of traditional herbal medicine for ischemic stroke: from bench to clinic-A critical review

BACKGROUND

Ischemic stroke (IS) is a leading cause of death and severe long-term disability worldwide. Over the past few decades, considerable progress has been made in anti-ischemic therapies. However, IS remains a tremendous challenge, with favourable clinical outcomes being generally difficult to achieve from candidate drugs in preclinical phase testing. Traditional herbal medicine (THM) has been used to treat stroke for over 2,000 years in China. In modern times, THM as an alternative and complementary therapy have been prescribed in other Asian countries and have gained increasing attention for their therapeutic effects. These millennia of clinical experience allow THM to be a promising avenue for improving clinical efficacy and accelerating drug discovery.

PURPOSE

To summarise the clinical evidence and potential mechanisms of THMs in IS.

METHODS

A comprehensive literature search was conducted in seven electronic databases, including PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, the Chinese National Knowledge Infrastructure, the VIP Information Database, the Chinese Biomedical Literature Database, and the Wanfang Database, from inception to 17 June 2022 to examine the efficacy and safety of THM for IS, and to investigate experimental studies regarding potential mechanisms.

RESULTS

THM is widely prescribed for IS alone or as adjuvant therapy. In clinical trials, THM is generally administered within 72 h of stroke onset and are continuously prescribed for over 3 months. Compared with Western medicine (WM), THM combined with routine WM can significantly improve neurological function defect scores, promote clinical total effective rate, and accelerate the recovery time of stroke with fewer adverse effects (AEs). These effects can be attributed to multiple mechanisms, mainly anti-inflammation, antioxidative stress, anti-apoptosis, brain blood barrier (BBB) modulation, inhibition of platelet activation and thrombus formation, and promotion of neurogenesis and angiogenesis.

CONCLUSIONS

THM may be a promising candidate for IS management to guide clinical applications and as a reference for drug development.

The Protective Effect of Vitexin Compound B-1 on Rat Cerebral I/R Injury through a Mechanism Involving Modulation of miR-92b/NOX4 Pathway

BACKGROUND

Recent studies have uncovered that vitexin compound B-1 (VB-1) can protect neurons against hypoxia/reoxygenation (H/R)-induced oxidative injury through suppressing NOX4 expression.

OBJECTIVE

The aims of this study are to investigate whether VB-1 can protect the rat brain against ischemia/ reperfusion (I/R) injury and whether its effect on NOX4 expression is related to modulation of certain miRNAs expression.

METHODS

Rats were subjected to 2 h of cerebral ischemia followed by 24 h of reperfusion to establish an I/R injury model, which showed an increase in neurological deficit score and infarct volume concomitant with an upregulation of NOX4 expression, increase in NOX activity, and downregulation of miR-92b.

RESULTS

Administration of VB-1 reduced I/R cerebral injury accompanied by a reverse in NOX4 and miR-92b expression. Similar results were achieved in a neuron H/R injury model. Next, we evaluated the association of miR-92b with NOX4 by its mimics in the H/R model. H/R treatment increased neurons apoptosis concomitant with an upregulation of NOX4 and NOX activity while downregulation of miR-92b. All these effects were reversed in the presence of miR-92b mimics, confirming the function of miR-92b in suppressing NOX4 expression.

CONCLUSION

We conclude the protective effect of VB-1 against rat cerebral I/R injury through a mechanism involving modulation of miR-92b/NOX4 pathway.

Gastrodin ameliorates the lipopolysaccharide-induced neuroinflammation in mice by downregulating miR-107-3p

Background: Neuroinflammation plays a pivotal role in the pathogenesis of Central Nervous System (CNS) diseases. The phenolic glucoside gastrodin (GAS), has been known to treat CNS disorders by exerting anti-inflammatory activities. Our aim was to investigate the potential neuroprotective mechanisms of GAS on lipopolysaccharide (LPS)-induced mice. Methods: Male C57BL/6J mice were treated by LPS, before which GAS was adminisrated. The behavior tests such as forced swim test, tail suspension test, and elevated plus maze were performed to evaluate depressive-anxiety-like behaviors. A high-throughput sequencing (HTS) analysis was performed to screen out distinctive miRNAs which were validated using quantitative real-time PCR. Then, miRNA agomir or NC was injected stereotaxically into hippocampus of mice to explore the role of miRNA on GAS in response to LPS. Furthermore, Immunofluorescence and the hematoxylin and eosin (H&E) staining were employed to observe the cellular morphology. The protein levels of pro-inflammatory factors were evaluated by western blot. Finally, the target mRNA of miRNA was predicted using bioinformatics analysis. GO and KEGG enrichment analyses were conducted to clarify the potential function of target protein, which were visualized by bubble charts. Results: The behavioral data showed that mice in the LPS group had obvious depressive-anxiety-like behaviors, and 100 mg/kg GAS could improve these behavioral changes and alleviate the levels of pro-inflammatory cytokines in the hippocampus when mice were exposed to LPS for 6 h. Meanwhile, LPS-induced microglia and astrocyte activation in the CA1, CA2, CA3, and DG regions of the hippocampus were also reversed by GAS. Furthermore, miR-107-3p were screened out and verified for GAS in response to LPS. Importantly, miR-107-3p overexpression negatively abrogated the neuroprotective effects of GAS. Moreover, KPNA1 might be the target molecular of miR-107-3p. KPNA1 might regulate 12 neuroinflammation-related genes, which were mainly involved in cytokine-mediated signaling pathway. Conclusion: These results suggested that GAS might alleviate the LPS-induced neuroinflammation and depressive-anxiety-like behaviors in mice by downregulating miR-107-3p and upregulating the downstream target KPNA1. The indicates miR-107-3p may provide a new strategy for the treatment of CNS diseases.

Adenosine A2A Receptor Antagonist Improves Cognitive Impairment by Inhibiting Neuroinflammation and Excitatory Neurotoxicity in Chronic Periodontitis Mice

The adenosine A_2A receptor antagonist SCH58261 has been reported to have anti-inflammatory effects. However, its role in chronic periodontitis (CP)-induced cognitive impairment, which is associated with Porphyromonas gingivalis lipopolysaccharide (P. gingivalis LPS), remains unclear. This study investigated the role of SCH58261 in mice with CP-induced cognitive impairment. C57BL/6J mice were used to develop CP model by injecting 0.5 mg/kg P. gingivalis LPS into the palatal gingival sulcus of maxillary first molars twice a week for four weeks. The mice were divided into control, P. gingivalis LPS (P-LPS), P-LPS + SCH58261, and SCH58261 groups. The passive avoidance test (PAT) and Morris water maze (MWM) were used to assess cognition in mice. Furthermore, CD73/adenosine, neuroinflammation, glutamate transporters, and glutamate were assessed. Compared with the P-LPS group, 0.1 and 0.5 mg/kg SCH58261 increased latency and decreased error times in PAT, but increased platform crossing number in MWM. SCH58261 inhibited microglial activation, and decreased pro-inflammatory cytokines and glutamate levels, but increased GLT-1 and PSD95 expression in the hippocampus. This was the first report of SCH58261 treatment for CP-induced cognitive impairment, which may be related to its anti-inflammatory activities and anti-glutamate excitatory neurotoxicity. This suggests that SCH58261 can be used as a novel agent to treat cognitive impairment.

Genome-wide microRNA profiles identify miR-107 as a top miRNA associating with expression of the CYP3As and other drug metabolizing cytochrome P450 enzymes in the liver

Cytochrome P450 (CYP) drug metabolizing enzymes are responsible for the metabolism of over 70% of currently used medications with the CYP3A family being the most important CYP enzymes in the liver. Large inter-person variability in expression/activity of the CYP3As greatly affects drug exposure and treatment outcomes, yet the cause of such variability remains elusive. Micro-RNAs (miRNAs) are small noncoding RNAs that negatively regulate gene expression and are involved in diverse cellular processes including metabolism of xenobiotics and therapeutic outcomes. Target prediction and in vitro functional assays have linked several miRNAs to the control of CYP3A4 expression. Yet, their co-expression with CYP3As in the liver remain unclear. In this study, we used genome-wide miRNA profiling in liver samples to identify miRNAs associated with the expression of the CYP3As. We identified and validated both miR-107 and miR-1260 as strongly associated with the expression of CYP3A4, CYP3A5, and CYP3A43. Moreover, we found associations between miR-107 and nine transcription factors (TFs) that regulate CYP3A expression, with estrogen receptor alpha (ESR1) having the largest effect size. Including ESR1 and the other TFs in the regression model either diminished or abolished the associations between miR-107 and the CYP3As, indicating that the role of miR-107 in CYP3A expression may be indirect and occur through these key TFs. Indeed, testing the other nine CYPs previously shown to be regulated by ESR1 identified similar miR-107 associations that were dependent on the exclusion of ESR1 and other key TFs in the regression model. In addition, we found significant differences in miRNA expression profiles in liver samples between race and sex. Together, our results identify miR-107 as a potential epigenetic regulator that is strongly associated with the expression of many CYPs, likely via impacting the CYP regulatory network controlled by ESR1 and other key TFs. Therefore, both genetic and epigenetic factors that alter the expression of miR-107 may have a broad influence on drug metabolism.

Some miRNA expressions and their targets in ischemic stroke

Ischemic stroke (IS) is a global health challenge leading to life-long disabilities or the deaths of patients. IS is a complex disease where genetic and environmental factors are both concerned with the pathophysiology of the condition. Here, we aimed to investigate various microRNA (miRNA) expressions and their targets in IS. A rapid and accurate diagnosis of acute IS is important to perform appropriate treatment. Therefore, there is a need for a more rapid and simple tool to carry out an acute diagnosis of IS. miRNAs are small RNA molecules serving as precious biomarkers due to their easy detection and stability in blood samples. The present systematic review aimed to summarize previous studies investigating several miRNA expressions and their targets in IS.

lncRNA PINK1-AS Aggravates Cerebral Ischemia/Reperfusion Oxidative Stress Injury through Regulating ATF2 by Sponging miR-203

Ischemic stroke is a common disease that led to high mortality and high disability. NADPH oxidase 2- (NOX2-) mediated oxidative stress and long noncoding RNA have important roles in cerebral ischemia/reperfusion (CI/R) injury, whereas whether there is interplay between them remains to be clarified. This study was performed to observe the role of lncRNA PINK1-antisense RNA (PINK1-AS) in NOX2 expression regulation. An in vivo rat model (MCAO) and an in vitro cell model (H/R: hypoxia/reoxygenation) were utilized for CI/R oxidative stress injury investigation. The expression levels of lncRNA PINK1-AS, activating transcription factor 2 (ATF2), NOX2, and caspase-3 and the production level of ROS and cell apoptosis were significantly increased in CI/R injury model rats or in H/R-induced SH-SY5Y cells, but miR-203 was significantly downregulated. There was positive correlation between PINK1-AS expression level and ROS production level. PINK1-AS and ATF2 were found to be putative targets of miR-203. Knockdown of lncRNA PINK1-AS or ATF2 or the overexpression of miR-203 significantly reduced oxidative stress injury via inhibition of NOX2. Overexpression of lncRNA PINK1 significantly led to oxidative stress injury in SH-SY5Y cells through downregulating miR-203 and upregulating ATF2 and NOX2. lncRNA PINK1-AS and ATF2 were the targets of miR-203, and the lncRNA PINK1-AS/miR-203/ATF2/NOX2 axis plays pivotal roles in CI/R injury. Therefore, lncRNA PINK1-AS is a possible target for CR/I injury therapy by sponging miR-203.

A Systematic Review of Body Fluids Biomarkers Associated With Early Neurological Deterioration Following Acute Ischemic Stroke

Biomarkers are objectively measured biological properties of normal and pathological processes. Early neurological deterioration (END) refers to the deterioration of neurological function in a short time after the onset of acute ischemic stroke (AIS) and is associated with adverse outcomes. Although multiple biomarkers have been found to predict END, there are currently no suitable biomarkers to be applied in routine stroke care. According to the Preferred Reporting Items for Systematic Review standards, we present a systematic review, concentrating on body fluids biomarkers that have shown potential to be transferred into clinical practice. We also describe newly reported body fluids biomarkers that can supply different insights into the mechanism of END. In our review, 40 scientific papers were included. Depending on the various mechanisms, sources or physicochemical characteristics of body fluids biomarkers, we classified related biomarkers as inflammation, protease, coagulation, metabolism, oxidative stress, and excitatory neurotoxicity. The body fluids biomarkers whose related articles are limited or mechanisms are unknown are categorized as other biomarkers. The inflammation-related biomarkers, such as neutrophil-to-lymphocyte ratio and hypersensitive C-reactive protein, play a crucial role among the mentioned biomarkers. Considering the vast heterogeneity of stroke progression, using a single body fluids biomarker may not accurately predict the risk of stroke progression, and it is necessary to combine multiple biomarkers (panels, scores, or indices) to improve their capacity to estimate END.

MiR-375-3p mediates reduced pineal function in hypoxia-ischemia brain damage

The functional roles of microRNAs (miRNAs) have been studied in various diseases, including hypoxic-ischemic brain damage (HIBD). However, changes in the expression of miRNAs and the underlying mechanisms in the pineal gland during HIBD remain unknown. Based on the previous study by microRNA array, hundreds of miRNAs showed altered expression patterns in the pineal gland in a rat model of HIBD. MiR-375-3p was found to be significantly upregulated and abundant in the pineal gland. Further investigation in an in vitro HI model of pinealocytes showed that miRNA-375 exacerbated the damage to pineal function. After oxygen-glucose deprivation / reoxygenation (OGD/R), miR-375-3p expression increased, while aralkylamine N-acetyltransferase (AANAT) expression and melatonin (MT) secretion decreased. Overexpression of miRNA-375 in pinealocytes aggravated the influence of OGD/R on AANAT expression and MT secretion. Because miRNA-375 overexpression in pinealocytes induced decreased rasd1 mRNA and protein expression, rasd1 may mediate the effect of miR-375-3p on pineal function. Furthermore, miR-375-3p aggravated the cognitive impairment caused by HIBD in rats, as observed by Morris water maze test, and also affected emotion and circadian rhythm in HIBD-treated rats. Thus, miR-375-3p may be a key regulatory molecule in the pineal gland following HIBD, and targeting of miR-375-3p may represent a new strategy for the treatment of HIBD.

Glutamate transporters: Critical components of glutamatergic transmission

Glutamate is the major excitatory neurotransmitter in the vertebrate central nervous system. Once released, it binds to specific membrane receptors and transporters activating a wide variety of signal transduction cascades, as well as its removal from the synaptic cleft in order to avoid its extracellular accumulation and the overstimulation of extra-synaptic receptors that might result in neuronal death through a process known as excitotoxicity. Although neurodegenerative diseases are heterogenous in clinical phenotypes and genetic etiologies, a fundamental mechanism involved in neuronal degeneration is excitotoxicity. Glutamate homeostasis is critical for brain physiology and Glutamate transporters are key players in maintaining low extracellular Glutamate levels. Therefore, the characterization of Glutamate transporters has been an active area of glutamatergic research for the last 40 years. Transporter activity its regulated at different levels: transcriptional and translational control, transporter protein trafficking and membrane mobility, and through extensive post-translational modifications. The elucidation of these mechanisms has emerged as an important piece to shape our current understanding of glutamate actions in the nervous system.

MiR-30a-5p Regulates GLT-1 Function via a PKCα-Mediated Ubiquitin Degradation Pathway in a Mouse Model of Parkinson's Disease

Glutamate excitotoxicity is caused by dysfunctional glutamate transporters and plays an important role in the pathogenesis of Parkinson's disease (PD); however, the mechanisms that underlie the regulation of glutamate transporters in PD are still not fully elucidated. MicroRNAs(miRNA), which are abundant in astrocytes and neurons, have been reported to play key roles in regulating the translation of glutamate-transporter mRNA. In this study, we hypothesized that the miR-30a-5p contributes to the pathogenesis of PD by regulating the ubiquitin-mediated degradation of glutamate transporter 1 (GLT-1). We demonstrated that short-hairpin RNA-mediated knockdown of miR-30a-5p ameliorated motor deficits and pathological changes like astrogliosis and reactive microgliosis in a mouse model of PD (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice). Western blotting and immunofluorescent labeling revealed that miR-30a-5p suppressed the expression and function of GLT-1 in MPTP-treated mice and specifically in astrocytes treated with 1-methyl-4-phenylpyridinium (MPP⁺) (cell model of PD). Both in vitro and in vivo, we found that miR-30a-5p knockdown promoted glutamate uptake and increased GLT-1 expression by hindering GLT-1 ubiquitination and subsequent degradation in a PKCα-dependent manner. Therefore, we conclude that miR-30a-5p represents a potential therapeutic target for the treatment of PD.

MiRNA-107 contributes to inflammatory pain by down-regulating GLT-1 expression in rat spinal dorsal horn

BACKGROUND

Inflammatory pain is a severe clinical problem that affects the quality of life in patients. However, the currently available treatments for inflammatory pain have limited effect and even causes severe side effects. The aim of this study was to investigate the roles of miRNA-107 and glutamate transporter 1 (GLT-1) in the inflammatory pain of rats induced by complete Freund's adjuvant (CFA).

METHODS

Paw withdrawal threshold (PWT) of rats was measured by von Frey Filaments. The expressions of miRNA-107 and GLT-1 in the lumbar spinal dorsal horn (L4-L6) were measured with real-time quantitative PCR and western blotting analysis. Fluorescent in situ hybridization and fluorescent-immunohistochemistry were employed to detect the expression of miRNA-107, GLT-1 and co-location of miRNA-107 with GLT-1.

RESULTS

Injection of CFA significantly reduced PWT of rats. The miRNA-107 expression level was obviously up-regulated while the GLT-1 expression level was decreased in the spinal dorsal horn of CFA rats. miRNA-107 and GLT-1 were co-expressed in the same cells of the spinal dorsal horn in CFA rats. Ceftriaxone, a selective activator of GLT-1, obviously increased the PWT of CFA rats. Furthermore, antagomir of miRNA-107 reversed the down-regulation of GLT-1 and alleviated CFA-induced mechanical allodynia of CFA rats.

CONCLUSIONS

These results suggest that an increase of miR-107 contributes to inflammatory pain through downregulating GLT-1 expression, implying a promising strategy for pain therapy.

SIGNIFICANCE

The currently available treatments for inflammatory pain has limited effect even causes severe side effects. MiRNAs may have important diagnostic and therapeutic potential in inflammatory pain. In present study, we show a potential spinal mechanism of allodynia in rat inflammatory pain model induced by CFA. Increased miR-107 contribute to inflammatory pain by targeting and downregulating GLT-1 expression, implying a promising strategy for inflammatory pain.

MicroRNA: An Emerging Predictive, Diagnostic, Prognostic and Therapeutic Strategy in Ischaemic Stroke

Stroke continues to be the third-leading cause of death and disability worldwide. The limited availability of diagnostic tools approved therapeutics and biomarkers that help monitor disease progression or predict future events remain as the major challenges in the field of stroke medicine. Hence, attempts to discover safe and efficacious therapeutics and reliable biomarkers are of paramount importance. MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in regulating gene expression. Since miRNAs also play important roles in key mechanisms associated with the pathogenesis of stroke, including energy failure, inflammation and cell death, it is possible that miRNAs may serve as reliable blood-based markers for risk prediction, diagnosis and prognosis of ischaemic stroke. Discovery of better neurological outcome and smaller cerebral infarcts in animal models of ischaemic stroke treated with miRNA agomirs or antagomirs indicate that miRNAs may also play a cerebrovascular protective role after an ischaemic stroke. Nonetheless, further evidences on the optimum time for treatment and route of administration are required before effective translation of these findings into clinical practice. Bearing these in mind, this paper reviews the current literature discussing the involvement of miRNAs in major pathologies associated with ischaemic stroke and evaluates their value as reliable biomarkers and therapeutics for ischaemic stroke.

Can miRNAs Be Considered as Diagnostic and Therapeutic Molecules in Ischemic Stroke Pathogenesis?-Current Status

Ischemic stroke is one of the leading causes of death worldwide. Clinical manifestations of stroke are long-lasting and causing economic burden on the patients and society. Current therapeutic modalities to treat ischemic stroke (IS) are unsatisfactory due to the intricate pathophysiology and poor functional recovery of brain cellular compartment. MicroRNAs (miRNA) are endogenously expressed small non-coding RNA molecules, which can act as translation inhibitors and play a pivotal role in the pathophysiology associated with IS. Moreover, miRNAs may be used as potential diagnostic and therapeutic tools in clinical practice; yet, the complete role of miRNAs is enigmatic during IS. In this review, we explored the role of miRNAs in the regulation of stroke risk factors viz., arterial hypertension, metabolic disorders, and atherosclerosis. Furthermore, the role of miRNAs were reviewed during IS pathogenesis accompanied by excitotoxicity, oxidative stress, inflammation, apoptosis, angiogenesis, neurogenesis, and Alzheimer's disease. The functional role of miRNAs is a double-edged sword effect in cerebral ischemia as they could modulate pathological mechanisms associated with risk factors of IS. miRNAs pertaining to IS pathogenesis could be potential biomarkers for stroke; they could help researchers to identify a particular stroke type and enable medical professionals to evaluate the severity of brain injury. Thus, ascertaining the role of miRNAs may be useful in deciphering their diagnostic role consequently it is plausible to envisage a suitable therapeutic modality against IS.

Low expression of miR‑532‑3p contributes to cerebral ischemia/reperfusion oxidative stress injury by directly targeting NOX2

NADPH oxidase 2 (NOX2) is a major subtype of NOX and is responsible for the generation of reactive oxygen species (ROS) in brain tissues. MicroRNAs (miRNAs/miRs) are important epigenetic regulators of NOX2. The present study aimed to identify the role of NOX2 miRNA-targets in ischemic stroke (IS). A rat cerebral ischemia/reperfusion (CI/R) injury model and a SH-SY5Y cell hypoxia/reoxygenation (H/R) model were used to simulate IS. Gene expression levels, ROS production and apoptosis in tissue or cells were determined, and bioinformatic analysis was conducted for target prediction of miRNA. In vitro experiments, including function-gain and luciferase activity assays, were also performed to assess the roles of miRNAs. The results indicated that NOX2 was significantly increased in brain tissues subjected to I/R and in SH-SY5Y cells subjected to H/R, while the expression of miR-532-3p (putative target of NOX2) was significantly decreased in brain tissues and plasma. Overexpression of miR-532-3p significantly suppressed NOX2 expression and ROS generation in SH-SY5Y cells subjected to H/R, as well as reduced the relative luciferase activity of cells transfected with a reporter gene plasmid. Collectively, these data indicated that miR-532-3p may be a target of NOX2 and a biomarker for CI/R injury. Thus, the present study may provide a novel target for drug development and IS therapy.

Circulating RNAs as Potential Biomarkers in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a complex multi-system neurodegenerative disorder with currently limited diagnostic and no therapeutic options. Despite the intense efforts no clinically applicable biomarkers for ALS are yet established. Most current research is thus focused, in particular, in identifying potential non-invasive circulating biomarkers for more rapid and accurate diagnosis and monitoring of the disease. In this review, we have focused on messenger RNA (mRNA), non-coding RNAs (lncRNAs), micro RNAs (miRNAs) and circular RNA (circRNAs) as potential biomarkers for ALS in peripheral blood serum, plasma and cells. The most promising miRNAs include miR-206, miR-133b, miR-27a, mi-338-3p, miR-183, miR-451, let-7 and miR-125b. To test clinical potential of this miRNA panel, a useful approach may be to perform such analysis on larger multi-center scale using similar experimental design. However, other types of RNAs (lncRNAs, circRNAs and mRNAs) that, together with miRNAs, represent RNA networks, have not been yet extensively studied in blood samples of patients with ALS. Additional research has to be done in order to find robust circulating biomarkers and therapeutic targets that will distinguish key RNA interactions in specific ALS-types to facilitate diagnosis, predict progression and design therapy.

MicroRNA-193b-3p alleviates focal cerebral ischemia and reperfusion-induced injury in rats by inhibiting 5-lipoxygenase expression

AIMS

Ischemic stroke has become one of the main causes of death worldwide. MicroRNAs (miRNAs) have been implicated in cerebral ischemia-reperfusion (I/R) injury and could serve as therapeutic targets. 5-Lipoxygenase (5-LOX) is a key enzyme in the biosynthesis of leukotrienes and has been implicated in inflammatory central nerve system disorders. The objective of this study was to explore the neuroprotective effects of miR-193b-3p against focal cerebral I/R injury in rats by regulating 5-LOX expression.

METHODS AND MATERIALS

Adult male Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion and reperfusion injury. The level of miR-193b-3p expression was observed in the rat cortical peri-infarct region after focal cerebral I/R injury. Bioinformatics analysis was used to predict the binding sites of miR-193b-3p, and a dual-luciferase reporter gene assay was applied to verify the potential interaction between 5-LOX mRNA and miR-193b-3p. Then, rats were injected with a miR-193b-3p agomir (modified and enhanced mimic) or antagomir (modified and enhanced inhibitor) in the right lateral ventricle of the brain. Neurological deficit scores, infarct volumes, neuron damage and 5-LOX enzymatic activity and expression were measured. In an in vitro experiment, cultured PC12 cells were exposed to oxygen-glucose deprivation and reperfusion (OGD/R). OGD/R-induced cells were treated with a miR-193b-3p mimic or inhibitor and 5-LOX siRNA. Cell viability, lactate dehydrogenase release, apoptosis rate and 5-LOX expression were evaluated.

RESULTS

The level of miR-193b-3p expression was increased in the cortical peri-infarct region of rats with cerebral focal I/R injury. The results of the dual-luciferase reporter gene assay showed that a miR-193b-3p binding site was located in the 3' untranslated region (3'UTR) of 5-LOX mRNA. Neurological deficit scores, infarct volumes and neuronal injury were alleviated by miR-193b-3p agomir treatment but aggravated by miR-193b-3p antagomir. Furthermore, leukotriene B4, cysteinyl-leukotrienes and 5-LOX expression in the cortical peri-infarct region of rats with focal cerebral I/R injury were also downregulated by miR-193b-3p agomir treatment but upregulated by miR-193b-3p antagomir. In PC12 cells, miR-193b-3p mimic significantly decreased OGD/R-induced cell death and reduced lactate dehydrogenase release and 5-LOX expression. In contrast, miR-193b-3p inhibitor exacerbated OGD/R-induced injury in PC12 cells. Additionally, the in vitro effects of miR-193b-3p inhibitor on OGD/R-induced cell injury were partially reversed by 5-LOX siRNA treatment.

CONCLUSION

MiR-193b-3p has a potentially neuroprotective effect on focal cerebral I/R-induced injury by inhibiting 5-LOX expression.

miR-652 protects rats from cerebral ischemia/reperfusion oxidative stress injury by directly targeting NOX2

Ischemic stroke is a devastating central nervous disease associated with oxidative stress and NOX2 is the main source of ROS responsible for brain tissue. miRNAs are a class of negative regulator of genes in mammals and involves the pathogenesis of ischemic stroke. This study aims to observe the role of target miRNA(miR-652) of NOX2 in ischemic stroke. A rat cerebral ischemia/reperfusion (CI/R) injury model and an SH-SY5Y cell hypoxia/reoxygenation(H/R) model were used to simulate ischemic stroke, and corresponding gene expression, biochemical indicators and pathophysiological indicators were measured to observe the role of miR-652. NOX2 significantly increased in brain tissues subjected to I/R or in SH-SY5Y cells subjected to H/R, while the expression level of miR-652(potential target of NOX2) significantly decreased in both brain tissues and plasma. Overexpression of miR-652 significantly suppressed NOX2 expression and ROS generation in H/R treated SH-SY5Y cells and reduced the relative luciferase activity of cells transfected with plasmid NOX2-WT (reporter gene plasmid). MiR-652 agomir significantly decreased the expression of NOX2 and ROS generation in brain tissues of CIR rats, as well as tissue injury. These data indicated that miR-652 protected rats from cerebral ischemia reperfusion injury by directly targeting NOX2, is a novel target for ischemic stroke therapy.

Epigenetic Regulation of Excitatory Amino Acid Transporter 2 in Neurological Disorders

Excitatory amino acid transporter 2 (EAAT2) is the predominant astrocyte glutamate transporter involved in the reuptake of the majority of the synaptic glutamate in the mammalian central nervous system (CNS). Gene expression can be altered without changing DNA sequences through epigenetic mechanisms. Mechanisms of epigenetic regulation, include DNA methylation, post-translational modifications of histones, chromatin remodeling, and small non-coding RNAs. This review is focused on neurological disorders, such as glioblastoma multiforme (GBM), Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), Parkinson’s disease (PD), bipolar disorder (BD), and neuroHIV where there is evidence that epigenetics plays a role in the reduction of EAAT2 expression. The emerging field of pharmaco-epigenetics provides a novel avenue for epigenetics-based drug therapy. This review highlights findings on the role of epigenetics in the regulation of EAAT2 in different neurological disorders and discusses the current pharmacological approaches used and the potential use of novel therapeutic approaches to induce EAAT2 expression in neurological disorders using CRISPR/Cas9 technology.

Down-regulation of miR-3068-3p enhances kcnip4-regulated A-type potassium current to protect against glutamate-induced excitotoxicity

The main cause of excitotoxic neuronal death in ischemic stroke is the massive release of glutamate. Recently, microRNAs (miRNAs) have been found to play an essential role in stroke pathology, although the molecular mechanisms remain to be investigated. Here, to identify potential candidate miRNAs involved in excitotoxicity, we treated rat primary cortical neurons with glutamate and found that miR-3068-3p, a novel miRNA, was up-regulated. We hypothesized that restoring miR-3068-3p expression might influence the neuronal injury outcomes. The inhibition of miR-3068-3p, using tough decoy lentiviruses, significantly attenuated the effects of glutamate on neuronal viability and intracellular calcium overload. To unravel the mechanisms, we employed bioinformatics analysis and RNA sequencing to identify downstream target genes. Additional luciferase assays and western blots validated kcnip4, a Kv4-mediated A-type potassium current (I_A ) regulator, as a direct target of miR-3068-3p. The inhibition of miR-3068-3p increased kcnip4 expression and vice versa. In addition, the knockdown of kcnip4 by shRNA abolished the protective effect of miR-3068-3p, and over-expressing kcnip4 alone was sufficient to play a neuroprotective role in excitotoxicity. Moreover the inhibition of miR-3068-3p enhanced the I_A density, and the pharmacological inhibition of I_A abrogated the protective role of miR-3068-3p inhibition and kcnip4 over-expression. Therefore, we conclude that inhibition of miR-3068-3p protects against excitotoxicity via its target gene, kcnip4, and kcnip4-regulated I_A . Our data suggest that the miR-3068-3p/kcnip4 axis may serve as a novel target for the treatment of ischemic stroke.

Altered expression of MiR-186-5p and its target genes after spinal cord ischemia-reperfusion injury in rats

Spinal cord ischemia-reperfusion (I/R) injury remains an unresolved problem, and the mechanism is not fully elaborated. In a rat model of spinal cord I/R injury, we performed microarray analysis to examine the altered expression of microRNAs (miRs) at 24 h after the modelling. miR-186-5p was chosen for further study. An miR mimic or anti-miR oligonucleotide was intrathecally infused before the surgical procedure. The participation of miR-186-5p and its potential target genes based on bioinformatics analysis were analysed next. Pre-treatment with the miR-186-5p mimic improved neurological function and histological assessment scores; reduced Evans Blue extravasation; attenuated spinal cord oedema; and decreased interleukin 15 (IL-15), IL-6, IL-1β, and tumour necrosis factor-α (TNF-α) expression at 24 h after the modelling. KEGG analysis showed that the group of potential target genes of miR-186-5p was notably enriched in several signalling cascades, such as the Wnt, Hippo, and PI3K-AKT pathways. Gene Ontology (GO) analysis revealed that the group of potential target genes of miR-186-5p was significantly enriched in several biological processes, such as 'Wnt signalling pathway', 'regulation of inflammatory response', and 'Toll-like receptor signalling pathway'. We further found that Wnt5a, TLR3, and chemokine (C-X-C motif) ligand 13 (CXCL13) were upregulated after the modelling and the miR-186-5p mimic reduced the induction of the aforementioned target genes. These data provide evidence that upregulation of miR-186-5p improves neurological outcomes induced by spinal cord I/R injury and may inhibit neuroinflammation through Wnt5a-, TLR3-, or CXCL13-mediated signal pathway in spinal cord I/R injury.

Circulating miR-127-3p as a Potential Biomarker for Differential Diagnosis in Frontotemporal Dementia

Given the heterogeneous nature of frontotemporal dementia (FTD), sensitive biomarkers are greatly needed for the accurate diagnosis of this neurodegenerative disorder. Circulating miRNAs have been reported as promising biomarkers for neurodegenerative disorders and processes affecting the central nervous system, especially in aging. The objective of the study was to evaluate if some circulating miRNAs linked with apoptosis (miR-29b-3p, miR-34a-5p, miR-16-5p, miR-17-5p, miR-107, miR-19b-3p, let-7b-5p, miR-26b-5p, and 127-3p) were able to distinguish between FTD patients and healthy controls. For this study, we enrolled 127 subjects, including 54 patients with FTD, 20 patients with Alzheimer's disease (AD), and 53 healthy controls. The qRT-PCR analysis showed a downregulation of miR-127-3p in FTD compared to controls, while the levels of other miRNAs remained unchanged. Then, miR-127-3p expression was also analyzed in AD patients, finding a different expression between two patient groups. A receiver operating characteristic curve was then created for miR-127-3p to discriminate FTD versus AD (AUC: 0.8986), and versus healthy controls (AUC: 0.8057). In conclusion, miR-127-3p could help to diagnose FTD and to distinguish it from AD.

Bioactive Ingredients in Chinese Herbal Medicines That Target Non-coding RNAs: Promising New Choices for Disease Treatment

Chinese herbal medicines (CHMs) are widely used in China and have long been a powerful method to treat diseases in Chinese people. Bioactive ingredients are the main components extracted from herbs that have therapeutic properties. Since artemisinin was discovered to inhibit malaria by Nobel laureate Youyou Tu, extracts from natural plants, particularly bioactive ingredients, have aroused increasing attention among medical researchers. The bioactive ingredients of some CHMs have been found to target various non-coding RNA molecules (ncRNAs), especially miRNAs, lncRNAs, and circRNAs, which have emerged as new treatment targets in numerous diseases. Here we review the evidence that, by regulating the expression of ncRNAs, these ingredients exert protective effects, including pro-apoptosis, anti-proliferation and anti-migration, anti-inflammation, anti-atherosclerosis, anti-infection, anti-senescence, and suppression of structural remodeling. Consequently, they have potential as treatment agents in diseases such as cancer, cardiovascular disease, nervous system disease, inflammatory bowel disease, asthma, infectious diseases, and senescence-related diseases. Although research has been relatively limited and inadequate to date, the promising choices and new alternatives offered by bioactive ingredients for the treatment of the above diseases warrant serious investigation.

Regulatory Mechanism of miR-543-3p on GLT-1 in a Mouse Model of Parkinson's Disease

Parkinson's disease (PD) features the degeneration and death of dopamine neurons in the substantia nigra pars compacta and the formation of Lewy bodies that contain α-synuclein. Among the numerous PD etiologies, glutamate excitotoxicity is a research hot spot, and glutamate transporters play key roles in this theory. It has been shown that the expression of the glutamate transporter is regulated by microRNAs. In this study, we found that the levels of expression and function of glutamate transporter type 1 (GLT-1) were significantly reduced and miR-543-3p was upregulated during the development of PD. Furthermore, our results indicated that GLT-1 plays an important role in the pathomechanism of PD. We found that miR-543-3p can suppress the expression and function of GLT-1 in MPP⁺-treated astrocytes and MPTP-treated mice. Inhibition of miR-543-3p can rescue the expression and function of GLT-1 and relieve dyskinesia in the PD model, which suggests that inhibition of miR-543-3p could serve as a potential therapeutic target for PD.

MicroRNA in Brain pathology: Neurodegeneration the Other Side of the Brain Cancer

The mammalian brain is made up of billions of neurons and supporting cells (glial cells), intricately connected. Molecular perturbations often lead to neurodegeneration by progressive loss of structure and malfunction of neurons, including their death. On the other side, a combination of genetic and cellular factors in glial cells, and less frequently in neurons, drive oncogenic transformation. In both situations, microenvironmental niches influence the progression of diseases and therapeutic responses. Dynamic changes that occur in cellular transcriptomes during the progression of developmental lineages and pathogenesis are controlled through a variety of regulatory networks. These include epigenetic modifications, signaling pathways, and transcriptional and post-transcriptional mechanisms. One prominent component of the latter is small non-coding RNAs, including microRNAs, that control the vast majority of these networks including genes regulating neural stemness, differentiation, apoptosis, projection fates, migration and many others. These cellular processes are also profoundly dependent on the microenvironment, stemness niche, hypoxic microenvironment, and interactions with associated cells including endothelial and immune cells. Significantly, the brain of all other mammalian organs expresses the highest number of microRNAs, with an additional gain in expression in the early stage of neurodegeneration and loss in expression in oncogenesis. However, a mechanistic explanation of the concept of an apparent inverse correlation between the odds of cancer and neurodegenerative diseases is only weakly developed. In this review, we thus will discuss widespread de-regulation of microRNAome observed in these two major groups of brain pathologies. The deciphering of these intricacies is of importance, as therapeutic restoration of pre-pathological microRNA landscape in neurodegeneration must not lead to oncogenesis and vice versa. We thus focus on microRNAs engaged in cellular processes that are inversely regulated in these diseases. We also aim to define the difference in microRNA networks between pro-survival and pro-apoptotic signaling in the brain.

Monogenic, Polygenic, and MicroRNA Markers for Ischemic Stroke

Ischemic stroke (IS) is a leading disease with high mortality and disability, as well as with limited therapeutic window. Biomarkers for earlier diagnosis of IS have long been pursued. Family and twin studies confirm that genetic variations play an important role in IS pathogenesis. Besides DNA mutations found previously by genetic linkage analysis for monogenic IS (Mendelian inheritance), recent studies using genome-wide associated study (GWAS) and microRNA expression profiling have resulted in a large number of DNA and microRNA biomarkers in polygenic IS (sporadic IS), especially in different IS subtypes and imaging phenotypes. The present review summarizes genetic markers discovered by clinical studies and discusses their pathogenic molecular mechanisms involved in developmental or regenerative anomalies of blood vessel walls, neuronal apoptosis, excitotoxic death, inflammation, neurogenesis, and angiogenesis. The possible impact of environment on genetics is addressed as well. We also include a perspective on further studies and clinical application of these IS biomarkers.

Are glutamate transporters neuroprotective or neurodegenerative during cerebral ischemia?

The accumulation of glutamate (Glu) in the synaptic cleft during cerebral ischemia triggers the death of neurons, causing mental or physical handicap. However, the mechanisms of the alteration in Glu homeostasis and the imbalance between the release and clearance of Glu in ischemia are not yet completely understood. Additionally, the role of Glu transporters in regulating Glu concentration in the synaptic cleft is controversial. This review aims to provide readers with an in-depth understanding of Glu transporters in the early or later stages of ischemic events, or in mild or severe cerebral ischemia via alteration of Glu transporter expression, reversal of Glu transporters function, and trafficking between membrane and cytoplasm, to further clarify whether the Glu transporters are neuroprotective or neurodegenerative during cerebral ischemia. We provide the insights for deeper understanding of the mechanism of Glu transporters regulation after different periods and severities of cerebral ischemia.

Microarray Data Analysis of Molecular Mechanism Associated with Stroke Progression

This study aimed to explore the molecular mechanism of stroke and provide a new target in the clinical management. The miRNA dataset GSE97532 (3 blood samples from middle cerebral artery occlusion (MCAO) and 3 from sham operation) and mRNA dataset GSE97533 (3 blood samples from MCAO and 3 from sham operation) were obtained from GEO database. Differentially expressed mRNA (DEGs) and miRNAs (DEMIRs) were screened out between MCAO and sham operation groups. Then, DEMIR-DEG interactions were explored and visualized using Cytoscape software. Moreover, the enrichment analysis was performed on these DEMIRs and DEGs. Furthermore, protein-protein interaction (PPI) network was constructed. Finally, the DEG-target transcription factors (TFs) were investigated using the WebGestal software. The current bioinformatics analysis revealed 38 DEMIRs and 546 DEGs between MCAO and sham operation groups. The DEMIR-DEG analysis revealed 370 relations, such as miR-107-5p-Furin. The top 10 up- and downregulated DEMIRs were mainly enriched in pathways like cAMP signaling pathway. The PPI network analysis revealed 2 modules. The target DEGs of the 10 up- and downregulated DEMIRs in 2 modules were mainly assembled in functions like ATP binding and pathway including ABC transporters. Furthermore, the DEG-TF network analysis identified 5 outstanding TFs including androgen receptor (AR). miR107-5p might take part in the progression of stroke via inhibiting the expression of Furin. TFs like AR might be used as a novel gene therapy target for stroke. Furthermore, cAMP signaling pathway and ATP binding function might be a novel breakthrough for stroke treatment.

MicroRNA-107 regulates anesthesia-induced neural injury in embryonic stem cell derived neurons

Ketamine, though widely used in pediatric anesthesia, may induce cortical neurotoxicity in young patients. This study focused on an in vitro model of rat brain embryonic stem cell (ESC)-derived neurons to investigate the effects of microRNA-107 (miR-107) on ketamine-induced neural injury. Rat brain ESCs were proliferated in vitro and differentiated toward neuronal fate. Ketamine induced neural injury in ESC-derived neurons was inspected by TUNEL and neurite growth assays. Ketamine-induce aberrant miR-107 expression was examined by qRT-PCR. MiR-107 was downregulated in ESCs through lentiviral transduction. Its effect on ketamine-induced neural injury in ESC-derived neurons was then examined. Potential downstream target of miR-107, brain derived neurotrophin factor (BDNF), was inspected by dual-luciferase reporter assay and qRT-PCR. BDNF was knocked down, through siRNA transfection, in NSCs to investigate its functional involvement in miR-107 mediated neural protection in ketamine-injured NSC-derived neurons. Ketamine induced apoptosis, neurite degeneration, and upregulated miR-107 in NSC-derived neurons. Lentivirus-mediated miR-107 downregulation attenuated ketamine-induced neural injury. BDNF was proven to be directly and inversely regulated by miR-107 in NSC-derived neurons. SiRNA-mediated BDNF inhibition reversed the protective effect of miR-107 downregulation on ketamine injury in NSC-derived neurons. MiR-107 / BDNF was demonstrated to be an important epigenetic signaling pathway in regulating ketamine-induced neural injury in cortical neurons. © 2018 The Authors. IUBMB Life published by Wiley Periodicals,Inc. on behalf of International Union of Biochemistry and Molecular Biology., 71(1):20-27, 2019.

Neuroprotection afforded by circadian regulation of intracellular glutathione levels: A key role for miRNAs

Circadian rhythms are approximately 24-h oscillations of physiological and behavioral processes that allow us to adapt to daily environmental cycles. Like many other biological functions, cellular redox status and antioxidative defense systems display circadian rhythmicity. In the central nervous system (CNS), glutathione (GSH) is a critical antioxidant because the CNS is extremely vulnerable to oxidative stress; oxidative stress, in turn, causes several fatal diseases, including neurodegenerative diseases. It has long been known that GSH level shows circadian rhythm, although the mechanism underlying GSH rhythm production has not been well-studied. Several lines of recent evidence indicate that the expression of antioxidant genes involved in GSH homeostasis as well as circadian clock genes are regulated by post-transcriptional regulator microRNA (miRNA), indicating that miRNA plays a key role in generating GSH rhythm. Interestingly, several reports have shown that alterations of miRNA expression as well as circadian rhythm have been known to link with various diseases related to oxidative stress. A growing body of evidence implicates a strong correlation between antioxidative defense, circadian rhythm and miRNA function, therefore, their dysfunctions could cause numerous diseases. It is hoped that continued elucidation of the antioxidative defense systems controlled by novel miRNA regulation under circadian control will advance the development of therapeutics for the diseases caused by oxidative stress.

Genome-wide Integration Study of Circulating miRNAs and Peripheral Whole-Blood mRNAs of Male Acute Ischemic Stroke Patients

Several circulating microRNAs (miRNAs) have been proved to serve as stable biomarkers in blood for acute ischemic stroke (AIS). However, the functions of these biomarkers remain elusive. By conducting the integration analysis of circulating miRNAs and peripheral whole-blood mRNAs using bioinformatics methods, we explored the biological role of these circulating markers in peripheral whole blood at the genome-wide level. Stroke-related circulating miRNA profile data (GSE86291) and peripheral whole-blood mRNA expression data (GSE16561) were collected from the Gene Expression Omnibus (GEO) datasets. We selected male patients to avoid any gender differences in stroke pathology. Male stroke-related miRNAs (M-miRNAs) and mRNAs (M-mRNAs) were detected using GEO2R. Nine M-miRNAs (five up- and four down-regulated) were applied to TargetScan to predict the possible target mRNAs. Next, we intersected these targets with the M-mRNAs (38 up- and three down-regulated) to obtain the male stroke-related overlapped mRNAs (Mo-mRNAs). Finally, we analyzed biological functions of Mo-mRNAs using the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), and constructed networks among the Mo-mRNAs, overlapped M-miRNAs (Mo-miRNAs), and their functions. The Mo-mRNAs were enriched in functions such as platelet degranulation, immune response, and pathways associated with phagosome biology and Staphylococcus aureus infection. This study provides an integrated view of interactions among circulating miRNAs and peripheral whole-blood mRNAs involved in the pathophysiological processes of male AIS.

Cardiovascular disease-related miRNAs expression: potential role as biomarkers and effects of training exercise

Cardiovascular diseases (CVDs) are one of the most important causes of mortality worldwide, therefore the need of effective preventive strategies is imperative. Aging is associated with significant changes in both cardiovascular structure and function that lower the threshold for clinical signs and symptoms, making older people more susceptible to CVDs morbidity and mortality. microRNAs (miRNAs) modulate gene expression at post-transcriptional level and increasing evidence has shown that miRNAs are involved in cardiovascular physiology and in the pathogenesis of CVDs. Physical activity is recommended by the medical community and the cardiovascular benefits of exercise are multifactorial and include important systemic effects on skeletal muscle, the peripheral vasculature, metabolism, and neuroendocrine systems, as well as beneficial modifications within the myocardium itself. In this review we describe the role of miRNAs and their dysregulation in several types of CVDs. We provide an overview of miRNAs in CVDs and of the effects of physical activity on miRNA regulation involved in both cardiovascular pathologies and age-related cardiovascular changes and diseases. Circulating miRNAs in response to acute and chronic sport exercise appear to be modulated following training exercise, and may furthermore serve as potential biomarkers for CVDs and different age-related CVDs.

TNFα and IL-1β modify the miRNA cargo of astrocyte shed extracellular vesicles to regulate neurotrophic signaling in neurons

Astrocytes are known to be critical regulators of neuronal function. However, relatively few mediators of astrocyte to neuron communication have been identified. Recent advancements in the biology of extracellular vesicles have begun to implicate astrocyte derived extracellular vesicles (ADEV) as mediators of astrocyte to neuron communication, suggesting that alterations in the release and/or composition of ADEVs could influence gliotransmission. TNFα and IL-1β are key mediators of glial activation and neuronal damage, but the effects of these cytokines on the release or molecular composition of ADEVs is unknown. We found that ADEVs released in response to IL-1β (ADEV-IL-1β) and TNFα (ADEV-TNFα) were enriched with miRNAs that target proteins involved in neurotrophin signaling. We confirmed that miR-125a-5p and miR-16-5p (both enriched in ADEV-IL-1β and ADEV-TNFα) targeted NTKR3 and its downstream effector Bcl2. Downregulation of these targets in neurons was associated with reductions in dendritic growth, dendritic complexity, reduced spike rates, and burst activity. Molecular interference of miR-125a-5p and miR-16-5p prevented ADEV-IL-1β from reducing dendritic complexity, spike, and burst rates. These findings suggest that astrocytes respond to inflammatory challenge by modifying the miRNA cargo of ADEVs to diminish the activity of target neurons by regulating the translational expression of proteins controlling programs essential for synaptic stability and neuronal excitability.

Circadian Regulation of Glutamate Transporters

L-glutamate is the major excitatory amino acid in the mammalian central nervous system (CNS). This neurotransmitter is essential for higher brain functions such as learning, cognition and memory. A tight regulation of extra-synaptic glutamate levels is needed to prevent a neurotoxic insult. Glutamate removal from the synaptic cleft is carried out by a family of sodium-dependent high-affinity transporters, collectively known as excitatory amino acid transporters. Dysfunction of glutamate transporters is generally involved in acute neuronal injury and neurodegenerative diseases, so characterizing and understanding the mechanisms that lead to the development of these disorders is an important goal in the design of novel treatments for the neurodegenerative diseases. Increasing evidence indicates glutamate transporters are controlled by the circadian system in direct and indirect manners, so in this contribution we focus on the mechanisms of circadian regulation (transcriptional, translational, post-translational and post-transcriptional regulation) of glutamate transport in neuronal and glial cells, and their consequence in brain function.

MicroRNA-107 prevents amyloid-β-induced neurotoxicity and memory impairment in mice

The pathogenesis of Alzheimer's disease (AD) has still not been fully elucidated, however it is thought that the build up of amyloid plaque at least partially causes the symptoms of AD. MicroRNAs (miRNAs) are endogenous non‑coding small RNA molecules that regulate the expression and degradation of proteins. The present study induced symptoms of AD in mice via intraventricular injection of amyloid‑β 1‑42 (Aβ1‑42), which decreased levels of miR‑107. However, miR‑107 levels increased following administration of miR‑107 mimic, a double‑stranded RNA molecule designed to imitate the native miRNA. Intraventricular injection of Aβ1‑42 aggregates led to spatial memory impairments, inhibited hippocampal long‑term potentiation (LTP) and resulted in the loss of pyramidal cells in the CA1 region of the hippocampus. The miR‑107 mimic reversed the impairments of spatial memory and LTP and the loss of pyramidal neurons caused by Aβ neurotoxicity. Furthermore, the miR‑107 mimic reversed the Aβ‑induced increase in Aβ1‑42 and phosphorylated Tau levels. Critically, Aβ1‑42 injection decreased levels of brain‑derived neurotrophic factor and reduced the phosphorylation of tyrosine receptor kinase B and protein kinase B; these changes were reversed following treatment with the miR‑107 mimic. Collectively, these results demonstrated that miR‑107 may be a potential target for the treatment of AD.

Interferon regulatory factor 2 binding protein 2: a new player of the innate immune response for stroke recovery

Ischemic brain injury triggers an inflammatory response. This response is necessary to clear damaged brain tissue but can also exacerbate brain injury. Microglia are the innate immune cells of the brain that execute this critical function. In healthy brain, microglia perform a housekeeping function, pruning unused synapses between neurons. However, microglia become activated to an inflammatory phenotype upon brain injury. Interferon regulatory factors modulate microglial activation and their production of inflammatory cytokines. This review briefly discusses recent findings pertaining to these regulatory mechanisms in the context of stroke recovery.

mir-193 targets ALDH2 and contributes to toxic aldehyde accumulation and tyrosine hydroxylase dysfunction in cerebral ischemia/reperfusion injury

MicroRNAs (miRNAs, miR) play a fundamental role in cerebral ischemia/reperfusion (I/R) injury. However, the role of miRNAs in toxic aldehyde and tyrosine accumulation is not fully elucidated. We constructed a cerebral I/R rat model and found that overexpression of miR-193 was associated with the accumulation of 4-Hydroxynonenal (4-HNE), Malondialdehyde (MDA), and tyrosine, and with the decrease of aldehyde dehydrogenase (ALDH2), tyrosine hydroxylase (TH), and dopamine. To unveil the molecular mechanism of the miR-193-mediated phenotype in I/R injury as described above, we performed bioinformatic analysis and found that ALDH2 was a potential target of miR-193. Through in vitro experiments (such as miR-193 mimic/inhibitor transfection, luciferase reporter gene plasmid transfection, and 4-HNE exposure) and in vivo infusion of miR-193 agomir, we demonstrated that miR-193 directly suppressed the expression of ALDH2 and led to toxic aldehyde accumulation, resulting in dysfunction of tyrosine hydroxylase. The present study suggests that the overexpression of miR-193 in a rat model exacerbated brain injury due to the following sequential process: targeted suppression of ALDH2, aldehyde accumulation, and tyrosine hydroxylase dysfunction, leading to tyrosine accumulation and insufficiency of dopamine synthesis.

Circulating pro-angiogenic and anti-angiogenic microRNA expressions in patients with acute ischemic stroke and their association with disease severity

The main objectives of this study are to evaluate 28 selected pro-angiogenic and anti-angiogenic microRNA (miRNA) expressions in plasma of acute ischemic stroke (AIS) patients and controls and to assess the correlations of these miRNAs with risk and severity of AIS. In the exploring stage, 10 AIS patients and 10 controls with vascular risk factors were enrolled. And in the validating stage, 106 AIS patients and 110 controls with the same eligibility were recruited. Blood samples were collected from participants within 24 h post the onset of symptoms, and plasma levels of miRNAs were evaluated by the qPCR method. In the exploring stage, 11 differentially expressed miRNAs (DEM) were identified and included into the validating stage. In the validating stage, the expression of miR-126, miR-130a, and miR-378 in plasma declined in the AIS patients; however, miR-222, miR-218, and miR-185 plasma levels were elevated. Univariate and multivariate logistic regression analysis disclosed that miR-126, miR-130a, miR-222, miR-218, and miR-185 were independent predicting factors for AIS. When these five DEMs were combined together, they presented a good diagnostic value with an area under curve (AUC) value of 0.767 (95% CI 0.705-0.829), sensitivity of 87.7%, and specificity of 54.5% at best cutoff point. Additionally, miR-126, miR-378, miR-101, miR-222, miR-218, and miR-206 were associated with National Institutes of Health Stroke Scale (NIHSS) score. Circulating miR-126, miR-130a, miR-222, miR-218, and miR-185 could be served as promising and independent biomarkers for risk of AIS, and miR-126, miR-378, miR-222, miR-101, miR-218, and miR-206 could be used for disease severity management of AIS.

Loss of IRF2BP2 in Microglia Increases Inflammation and Functional Deficits after Focal Ischemic Brain Injury

Ischemic stroke causes neuronal cell death and triggers a cascade of inflammatory signals that contribute to secondary brain damage. Microglia, the brain-resident macrophages that remove dead neurons, play a critical role in the brain’s response to ischemic injury. Our previous studies showed that IRF2 binding protein 2 (IRF2BP2) regulates peripheral macrophage polarization, limits their inflammatory response and reduces susceptibility to atherosclerosis. Here, we show that loss of IRF2BP2 in microglia leads to increased inflammatory cytokine expression in response to lipopolysaccharide challenge and impaired activation of anti-inflammatory markers in response to interleukin-4 (IL4) stimulation. Focal ischemic brain injury of the sensorimotor cortex induced by photothrombosis caused more severe functional deficits in mice with IRF2BP2 ablated in macrophages/microglia, associated with elevated expression of inflammatory cytokines in the brain. These mutant mice had larger infarctions 4 days after stroke associated with fewer anti-inflammatory M2 microglia/macrophages recruited to the peri-infarct area, suggesting an impaired clearance of injured tissues. Since IRF2BP2 modulates interferon signaling, and interferon beta (IFNβ) has been reported to be anti-inflammatory and reduce ischemic brain injury, we asked whether loss of IRF2BP2 in macrophages/microglia would affect the response to IFNβ in our stroke model. IFNβ suppressed inflammatory cytokine production of macrophages and reduced infarct volumes at 4 days after photothrombosis in wild type mice. The anti-inflammatory effect of IFNβ was lost in IRF2BP2-deficient macrophages and IFNβ failed to protect mice lacking IRF2BP2 in macrophages/microglia from ischemic injury. In summary, IRF2BP2 expression in macrophages/microglia is important to limit inflammation and stroke injury, in part by mediating the beneficial effect of IFNβ.

Depleted tumor suppressor miR-107 in plasma relates to tumor progression and is a novel therapeutic target in pancreatic cancer

This study explored decreased tumor suppressor microRNA (miRNA) plasma levels in pancreatic cancer (PCa) patients to clarify their potential as novel biomarkers and therapeutic targets. We used the microRNA array-based approach to select candidates by comparing plasma levels between PCa patients and healthy volunteers. Six down-regulated miRNAs (miR-107, miR-126, miR-451, miR-145, miR-491-5p, and miR-146b-5p) were selected. Small- and large-scale analyses using samples from 100 PCa patients and 80 healthy volunteers revealed that miR-107 was the most down-regulated miRNA in PCa patients compared with healthy volunteers (P < 0.0001; area under the receiver-operating characteristic curve, 0.851). A low miR-107 plasma level was significantly associated with advanced T stage, N stage, and liver metastasis and was an independent factor predicting poor prognosis in PCa patients (P = 0.0424; hazard ratio, 2.95). miR-107 overexpression in PCa cells induced G1/S arrest with the production of p21 and inhibited cell proliferation through the transcriptional regulation of Notch2. In vivo, the restoration and maintenance of the miR-107 plasma level significantly inhibited tumor progression in mice. Depletion of the tumor suppressor miR-107 in plasma relates to tumor progression and poor outcomes. The restoration of the plasma miR-107 level might be a novel anticancer treatment strategy for PCa.

MicroRNA in glutamate receptor-dependent neurological diseases

Glutamate-mediated excitotoxicity is the major neuropathological process contributing to numerous neurological diseases. Recently, emerging evidence indicates that microRNAs (miRNAs) play essential roles in the pathophysiology of a wide range of neurological diseases. Notably, there have been significant developments in understanding the biogenesis of miRNAs, their regulatory mechanisms, and their potential as effective biomarkers and therapies. In the present review, we summarize the recent literature that highlights the versatile roles played by miRNAs in glutamate receptor (GluR)-dependent neurological diseases. Based on the reported studies to date, modulation of miRNAs could emerge as a promising therapeutic target for a variety of neurological diseases that were discussed in this review.