The microRNA miR-181c controls microglia-mediated neuronal apoptosis by suppressing tumor necrosis factor

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.

MicroRNA (miRNA) as a biomarker for diagnosis, prognosis, and therapeutics molecules in neurodegenerative disease

Neurodegenerative diseases that include Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), Huntington's disease (HD), and multiple sclerosis (MS) that arise due to numerous causes like protein accumulation and autoimmunity characterized by neurologic depletion which lead to incapacity in normal physiological function such as thinking and movement in these patients. Glial cells perform an important role in protective neuronal function; in the case of neuroinflammation, glial cell dysfunction can promote the development of neurodegenerative diseases. miRNA that participates in gene regulation and plays a vital role in many biological processes in the body; in the central nervous system (CNS), it can play an essential part in neural maturation and differentiation. In neurodegenerative diseases, miRNA dysregulation occurs, enhancing the development of these diseases. In this review, we discuss neurodegenerative disease (Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS)) and how miRNA is preserved as a diagnostic biomarker or therapeutic agent in these disorders. Finally, we highlight miRNA as therapy.

Molecular Pathogenesis of Ischemic and Hemorrhagic Strokes: Background and Therapeutic Approaches

Stroke represents one of the neurological diseases most responsible for death and permanent disability in the world. Different factors, such as thrombus, emboli and atherosclerosis, take part in the intricate pathophysiology of stroke. Comprehending the molecular processes involved in this mechanism is crucial to developing new, specific and efficient treatments. Some common mechanisms are excitotoxicity and calcium overload, oxidative stress and neuroinflammation. Furthermore, non-coding RNAs (ncRNAs) are critical in pathophysiology and recovery after cerebral ischemia. ncRNAs, particularly microRNAs, and long non-coding RNAs (lncRNAs) are essential for angiogenesis and neuroprotection, and they have been suggested to be therapeutic, diagnostic and prognostic tools in cerebrovascular diseases, including stroke. This review summarizes the intricate molecular mechanisms underlying ischemic and hemorrhagic stroke and delves into the function of miRNAs in the development of brain damage. Furthermore, we will analyze new perspectives on treatment based on molecular mechanisms in addition to traditional stroke therapies.

Could MicroRNA be Neurological Prognosis Biomarkers after Cardiac Arrest?

For patients monitored in intensive care units in the aftermath of a cardiac arrest, one of the well-established difficulties of care after resuscitation is the ability to perform the necessary prognostic assessments as accurately and early as possible. Although current guidelines include algorithms to determine prognosis, there are still missing links and uncertainties. Biomarkers obtained from peripheral blood are generally non-invasive and easy to obtain. Although the potential to use microRNA as a prognostic biomarker after cardiac arrest has received less interest recently, its popularity has increased in the last few years. By identifying prognostic biomarkers within 24 h of cardiac arrest, clinicians in intensive care could gain valuable insights to guide patient outcomes and predict both mortality and survival rates.

Hyperforin ameliorates neuroinflammation and white matter lesions by regulating microglial VEGFR2 /SRC pathway in vascular cognitive impairment mice

AIM

To explore the neuroprotective potential of hyperforin and elucidate its underlying molecular mechanisms involved in its therapeutic effects against vascular cognitive impairment (VCI).

METHODS

The active compounds and possible targets of Hypericum perforatum L. that may be effective against VCI were found by network pharmacology in this research. We utilized bilateral common carotid artery occlusion (BCCAO) surgery to induce a VCI mouse model. Morris water maze (MWM) and Y-maze tests were used to assess VCI mice's cognitive abilities following treatment with hyperforin. To evaluate white matter lesions (WMLs), we utilized Luxol fast blue (LFB) stain and immunofluorescence (IF). Neuroinflammation was assessed using IF, western blot (WB), and enzyme-linked immunosorbent assay (ELISA). The effects of hyperforin on microglia were investigated by subjecting the BV2 microglial cell line to oxygen-glucose deprivation/reperfusion (OGD/R) stimulation. The expressions of VEGFR2 , p-SRC, SRC, VEGFA, and inflammatory markers including IL-10, IL-1β, TNF-α, and IL-6 were subsequently assessed.

RESULTS

The VEGFR2 /SRC signaling pathway is essential for mediating the protective properties of hyperforin against VCI according to network pharmacology analysis. In vivo findings demonstrated that hyperforin effectively improved BCCAO-induced cognitive impairment. Furthermore, staining results showed that hyperforin attenuated WMLs and reduced microglial activation in VCI mice. The hyperforin treatment group's ELISA results revealed a substantial decrease in IL-1β, IL-6, and TNF-α levels. According to the results of in vitro experiments, hyperforin decreased the release of pro-inflammatory mediators (TNF-α, IL-6, and IL-1β) and blocked microglial M1-polarization by modulating the VEGFR2 /SRC signaling pathway.

CONCLUSION

Hyperforin effectively modulated microglial M1 polarization and neuroinflammation by inhibiting the VEGFR2 /SRC signaling pathways, thereby ameliorating WMLs and cognitive impairment in VCI mice.

Hyperoside ameliorates cerebral ischaemic-reperfusion injury by opening the TRPV4 channel in vivo through the IP3-PKC signalling pathway

CONTEXT

Hyperoside (Hyp), one of the active flavones from Rhododendron (Ericaceae), has beneficial effects against cerebrovascular disease. However, the effect of Hyp on vasodilatation has not been elucidated.

OBJECTIVE

To explore the effect of Hyp on vasodilatation in the cerebral basilar artery (CBA) of Sprague-Dawley (SD) rats suffering with ischaemic-reperfusion (IR) injury.

MATERIALS AND METHODS

Sprague-Dawley rats were randomly divided into sham, model, Hyp, Hyp + channel blocker and channel blocker groups. Hyp (50 mg/kg, IC₅₀ = 18.3 μg/mL) and channel blocker were administered via tail vein injection 30 min before ischaemic, followed by 20 min of ischaemic and 2 h of reperfusion. The vasodilation, hyperpolarization, ELISA assay, haematoxylin-eosin (HE), Nissl staining and channel-associated proteins and qPCR were analysed. Rat CBA smooth muscle cells were isolated to detect the Ca²⁺ concentration and endothelial cells were isolated to detect apoptosis rate.

RESULTS

Hyp treatment significantly ameliorated the brain damage induced by IR and evoked endothelium-dependent vasodilation rate (47.93 ± 3.09% vs. 2.99 ± 1.53%) and hyperpolarization (-8.15 ± 1.87 mV vs. -0.55 ± 0.42 mV) by increasing the expression of IP3R, PKC, transient receptor potential vanilloid channel 4 (TRPV4), IK_Ca and SK_Ca in the CBA. Moreover, Hyp administration significantly reduced the concentration of Ca²⁺ (49.08 ± 7.74% vs. 83.52 ± 6.93%) and apoptosis rate (11.27 ± 1.89% vs. 23.44 ± 2.19%) in CBA. Furthermore, these beneficial effects of Hyp were blocked by channel blocker.

DISCUSSION AND CONCLUSIONS

Although Hyp showed protective effect in ischaemic stroke, more clinical trial certification is needed due to the difference between animals and humans.

Functional polymorphism in miR-208 is associated with increased risk for ischemic stroke

BACKGROUND

The miR-208 gene is one of the microRNAs now under active studies, and has been found to play significant roles in an array of cardiovascular diseases. Nevertheless, until now, no studies have examined the relationship between the susceptibility to ischemic stroke (IS) and genetic variations in miR-208. This study explored the association between the miR-208 polymorphisms (rs178642, rs8022522, and rs12894524) and the risk of IS.

METHODS

A total of 205 cases of IS and 211 control subjects were included. The SNPscans genotyping test was employed to determine the genotypes of the three polymorphisms.

RESULTS

Significant correlation was observed between rs8022522 polymorphism and risk of IS on the basis of analyses of genotypes, models and alleles (GA vs. GG: adjusted OR = 2.159, 95% CI: 1.052-4.430, P = 0. 036; AA vs. GG: adjusted OR = 5.154, 95% CI: 1.123-23.660, P = 0.035; dominant model: adjusted OR = 1.746, 95% CI, 1.075-2.838, P = 0.025; G vs. A: adjusted OR = 2.451, 95% CI: 1.374-4.370, P = 0.002).

CONCLUSIONS

The rs8022522 polymorphism of the miR-208 gene is significantly associated with an elevated risk of ischemic stroke in Chinese.

MiR-181c-5p ameliorates learning and memory in sleep-deprived mice via HMGB1/TLR4/NF-κB pathway

Sleep deprivation (SD) can lead to cognitive impairment caused by neuroinflammation. MiR-181c-5p/HMGB1 axis plays a part in anti-inflammation effects. However, the mechanism that miR-181c-5p facilitates learning and memory in SD mice remains unclear. So we investigated the role of miR-181c-5p in learning and memory impairment induced by SD. We overexpressed miR-181c-5p in the mice hippocampus by injecting lentivirus vector-miR-181c-5p (LV-miR-181c-5p) particles. Mice were divided into four groups: control (Ctrl), SD, SD + miR-181c-5p and SD + vector. We found that mice in the third group showed ameliorated learning and memory compared with the fourth group. The content of ionized calcium binding adaptor molecule 1 (IBA-1) in the third group was decreased compared with the fourth group. Moreover, the expression levels of HMGB1, TLR4 and p-NF-κB in the hippocampus of overexpressed miR-181c-5p mice were reduced. In total, miR-181c-5p ameliorated learning and memory in SD mice via the HMGB1/TLR4/NF-κB pathway.

Viral-induced neuronal necroptosis: Detrimental to brain function and regulation by necroptosis inhibitors

Neuronal necroptosis (programmed necrosis) in the CNS naturally occurs through a caspase-independent way and, especially in neurodegenerative diseases (NDDs) such as Alzheimer's disease (AD), Parknson's disease (PD), Amyotrophic Lateral Sclerosis (ALS) and viral infections. Understanding necroptosis pathways (death receptor-dependent and independent), and its connections with other cell death pathways could lead to new insights into treatment. Receptor-interacting protein kinase (RIPK) mediates necroptosis via mixed-lineage kinase-like (MLKL) proteins. RIPK/MLKL necrosome contains FADD, procaspase-8-cellular FLICE-inhibitory proteins (cFLIPs), RIPK1/RIPK3, and MLKL. The necrotic stimuli cause phosphorylation of MLKL and translocate to the plasma membrane, causing an influx of Ca2+ and Na+ ions and, the immediate opening of mitochondrial permeability transition pore (mPTP) with the release of inflammatory cell damage-associated molecular patterns (DAMPs) like mitochondrial DNA (mtDNA), high-mobility group box1 (HMGB1), and interleukin1 (IL-1). The MLKL translocates to the nucleus to induce transcription of the NLRP3 inflammasome complex elements. MLKL-induced NLRP3 activity causes caspase-1 cleavage and, IL-1 activation which promotes neuroinflammation. RIPK1-dependent transcription increases illness-associated microglial and lysosomal abnormalities to facilitate amyloid plaque (Aβ) aggregation in AD. Recent research has linked neuroinflammation and mitochondrial fission with necroptosis. MicroRNAs (miRs) such as miR512-3p, miR874, miR499, miR155, and miR128a regulate neuronal necroptosis by targeting key components of necroptotic pathways. Necroptosis inhibitors act by inhibiting the membrane translocation of MLKL and RIPK1 activity. This review insights into the RIPK/MLKL necrosome-NLRP3 inflammasome interactions during death receptor-dependent and independent neuronal necroptosis, and clinical intervention by miRs to protect the brain from NDDs.

Dual Effects of miR-181b-2-3p/SOX21 Interaction on Microglia and Neural Stem Cells after Gamma Irradiation

Ionizing radiation induces brain inflammation and the impairment of neurogenesis by activating microglia and inducing apoptosis in neurogenic zones. However, the causal relationship between microglial activation and the impairment of neurogenesis as well as the relevant molecular mechanisms involved in microRNA (miR) remain unknown. In the present study, we employed immunohistochemistry and real-time RT-PCR to study the microglial activation and miRNA expression in mouse brains. Real-time RT-PCR, western blot, ELISA, cell proliferation and cytotoxicity assay were used in BV2 and mouse neural stem cells (NSCs). In the mouse model, we found the acute activation of microglia at 1 day and an increased number of microglial cells at 1, 7 and 120 days after irradiation at postnatal day 3 (P3), day 10 (P10) and day 21 (P21), respectively. In cell models, the activation of BV2, a type of microglial cell line, was observed after gamma irradiation. Real-time RT-PCR analysis revealed a deceased expression of miR-181b-2-3p and an increased expression of its target SRY-related high-mobility group box transcription factor 21 (SOX21) in a dose- and time-dependent fashion. The results of the luciferase reporter assay confirmed that SOX21 was the target of miR-181b-2-3p. Furthermore, SOX21 knockdown by siRNA inhibited the activation of microglia, thereby suggesting that the direct interaction of 181b-2-3p with SOX21 might be involved in radiation-induced microglial activation and proliferation. Interestingly, the gamma irradiation of NSCs increased miR-181b-2-3p expression but decreased SOX21 mRNA, which was the opposite of irradiation-induced expression in BV2 cells. As irradiation reduced the viability and proliferation of NSCs, whereas the overexpression of SOX21 restored the impaired cell viability and promoted the proliferation of NSCs, the findings suggest that the radiation-induced interaction of miR-181b-2-3p with SOX21 may play dual roles in microglia and NSCs, respectively, leading to the impairment of brain neurogenesis.

The Role of Mitochondria-Targeting miRNAs in Intracerebral Hemorrhage

Non-traumatic intracerebral hemorrhage (ICH) is the most common type of hemorrhagic stroke, most often occurring between the ages of 45 and 60. Arterial hypertension (AH) is most often the cause of ICH, followed by atherosclerosis, blood diseases, inflammatory changes in cerebral vessels, intoxication and vitamin deficiencies. Cerebral hemorrhage can occur by diapedesis or as a result of a ruptured vessel. AH is difficult to treat, requires surgery and can lead to disability or death. One of the important directions in the study of the pathogenesis of ICH is mitochondrial dysfunction and its regulation. The key role of mitochondrial dysfunction in AH and atherosclerosis, as well as in the development of brain damage after hemorrhage, has been acknowledged. MicroRNAs (miRNAs) are a class of non-coding RNAs (about 18-22 nucleotides) that regulate a variety of biological processes including cell differentiation, proliferation, apoptosis, etc., primarily through gene repression. There is growing evidence to support dysregulated miRNAs in various cardiovascular diseases, including ICH. Further, the realization of miRNAs within mitochondrial compartment has challenged the traditional knowledge of signaling pathways involved in the regulatory network of cardiovascular diseases. However, the role of miRNAs in mitochondrial dysfunction for ICH is still under-appreciated, with comparatively much lesser studies and investigations reported, than those in other cardiovascular diseases. In this review, we summarize the up-to-date findings on the published role miRNAs in mitochondrial function for ICH, and the potential use of miRNAs in clinical settings, such as potential therapeutic targets and non-invasive diagnostic/prognostic biomarker tools.

Molecular Autopsy in Asphyxia Deaths: Diagnostic Perspectives of miRNAs in the Evaluation of Hypoxia Response

The forensic investigation of asphyxia deaths still poses a challenge due to the need to demonstrate vital exposure to hypoxic insult according to high levels of evidence. The pulmonary effects of hypoxia are complex and the understanding of the mechanisms underlying the acute pneumotoxicity induced by hypoxia is still incomplete. Redox imbalance has been suggested as the protagonist of the main acute changes in pulmonary function in the hypoxic context. The development of knowledge in biochemistry and molecular biology has allowed research in forensic pathology to identify some markers useful in immunohistochemical diagnostics of asphyxia deaths. Several studies have highlighted the diagnostic potential of markers belonging to the HIF-1α and NF-kB pathways. The central role of some highly specific microRNAs has recently been recognized in the complex molecular mechanisms involved in the hypoxia response; thus, several research activities are currently aimed at identifying miRNAs involved in the regulation of oxygen homeostasis (hypoxamiR). The aim of the manuscript is to identify, the miRNAs involved in the early stages of the cellular response to hypoxia, in order to characterize the possible implications in the forensic field of the determination of expression profiles. At present, more than 60 miRNAs involved in the hypoxia response with different expression profiles (upregulation and downregulation) have been identified. Despite the multiple and different effects on reprogramming following the hypoxic insult, the evaluation of the diagnostic implications of hypoxamiRs in the forensic field presupposes a specific treatment of the influences on HIF-1α regulation, cell cycle progression, DNA repair, and apoptosis.

Serum microRNAs associated with concussion in football players

Mild Traumatic Brain Injury (mild TBI)/concussion is a common sports injury, especially common in football players. Repeated concussions are thought to lead to long-term brain damage including chronic traumatic encephalopathy (CTE). With the worldwide growing interest in studying sport-related concussion the search for biomarkers for early diagnosis and progression of neuronal injury has also became priority. MicroRNAs are short, non-coding RNAs that regulate gene expression post-transcriptionally. Due to their high stability in biological fluids, microRNAs can serve as biomarkers in a variety of diseases including pathologies of the nervous system. In this exploratory study, we have evaluated changes in the expression of selected serum miRNAs in collegiate football players obtained during a full practice and game season. We found a miRNA signature that can distinguish with good specificity and sensitivity players with concussions from non-concussed players. Furthermore, we found miRNAs associated with the acute phase (let-7c-5p, miR-16-5p, miR-181c-5p, miR-146a-5p, miR-154-5p, miR-431-5p, miR-151a-5p, miR-181d-5p, miR-487b-3p, miR-377-3p, miR-17-5p, miR-22-3p, and miR-126-5p) and those whose changes persist up to 4 months after concussion (miR-17-5p and miR-22-3p).

Neuronal and Glial Communication via Non-Coding RNAs: Messages in Extracellular Vesicles

Extracellular vesicles (EVs) have been increasingly recognized as essential players in cell communication in many organs and systems, including the central nervous system (CNS). A proper interaction between neural cells is fundamental in the regulation of neurophysiological processes and its alteration could induce several pathological phenomena, such as neurodegeneration, neuroinflammation, and demyelination. EVs contain and transfer complex molecular cargoes typical of their cells of origin, such as proteins, lipids, carbohydrates, and metabolites to recipient cells. EVs are also enriched in non-coding RNAs (e.g., microRNAs, lncRNAs, and circRNA), which were formerly considered as cell-intrinsic regulators of CNS functions and pathologies, thus representing a new layer of regulation in the cell-to-cell communication. In this review, we summarize the most recent and advanced studies on the role of EV-derived ncRNAs in the CNS. First, we report the potential of neural stem cell-derived ncRNAs as new therapeutic tools for neurorepair. Then, we discuss the role of neuronal ncRNAs in regulating glia activation, and how alteration in glial ncRNAs influences neuronal survival and synaptic functions. We conclude that EV-derived ncRNAs can act as intercellular signals in the CNS to either propagate neuroinflammatory waves or promote reparative functions.

Effect of chronic intermittent ethanol vapor exposure on RNA content of brain-derived extracellular vesicles

Extracellular vesicles (EVs) are important players in normal biological function and disease pathogenesis. Of the many biomolecules packaged into EVs, coding and noncoding RNA transcripts are of particular interest for their ability to significantly alter cellular and molecular processes. Here we investigate how chronic ethanol exposure impacts EV RNA cargo and the functional outcomes of these changes. Following chronic intermittent ethanol (CIE) vapor exposure, EVs were isolated from male and female C57BL/6J mouse brain. Total RNA from EVs was analyzed by lncRNA/mRNA microarray to survey changes in RNA cargo following vapor exposure. Differential expression analysis of microarray data revealed a number of lncRNA and mRNA types differentially expressed in CIE compared to control EVs. Weighted gene co-expression network analysis identified multiple male and female specific modules related to neuroinflammation, cell death, demyelination, and synapse organization. To functionally test these changes, whole-cell voltage-clamp recordings were used to assess synaptic transmission. Incubation of nucleus accumbens brain slices with EVs led to a reduction in spontaneous excitatory postsynaptic current amplitude, although no changes in synaptic transmission were observed between control and CIE EV administration. These results indicate that CIE vapor exposure significantly changes the RNA cargo of brain-derived EVs, which have the ability to impact neuronal function.

microRNAs associated with the pathogenesis and their role in regulating various signaling pathways during Mycobacterium tuberculosis infection

Despite more than a decade of active study, tuberculosis (TB) remains a serious health concern across the world, and it is still the biggest cause of mortality in the human population. Pathogenic bacteria recognize host-induced responses and adapt to those hostile circumstances. This high level of adaptability necessitates a strong regulation of bacterial metabolic characteristics. Furthermore, the immune reponse of the host virulence factors such as host invasion, colonization, and survival must be properly coordinated by the pathogen. This can only be accomplished by close synchronization of gene expression. Understanding the molecular characteristics of mycobacterial pathogenesis in order to discover therapies that prevent or resolve illness relies on the bacterial capacity to adjust its metabolism and replication in response to various environmental cues as necessary. An extensive literature details the transcriptional alterations of host in response to in vitro environmental stressors, macrophage infection, and human illness. Various studies have recently revealed the finding of several microRNAs (miRNAs) that are believed to play an important role in the regulatory networks responsible for adaptability and virulence in Mycobacterium tuberculosis. We highlighted the growing data on the existence and quantity of several forms of miRNAs in the pathogenesis of M. tuberculosis, considered their possible relevance to disease etiology, and discussed how the miRNA-based signaling pathways regulate bacterial virulence factors.

MicroRNA expression within neuronal-derived small extracellular vesicles in frontotemporal degeneration

MicroRNAs (miRNAs) are small non-coding RNA that are powerful regulators of gene expression and can affect the expression of hundreds of genes. miRNAs can be packed in small extracellular vesicles (SEV) and released into the extracellular space by neurons and microglia to act locally as well as pass through the blood-brain barrier and act systemically. We sought to understand the differences in neuronal SEV miRNA expression between frontotemporal dementia (FTD), Alzheimer's disease (AD), and healthy aging. Plasma was obtained from FTD, AD, and healthy aging participants that were matched based on age, sex, and race/ethnicity. Additionally, a subset of participants also provided paired cerebrospinal fluid samples to compare neuronal SEV miRNAs in plasma and cerebrospinal fluid. Neuronal SEV were isolated using differential ultracentrifugation and antibody conjugated Dynabeads® for the neuronal surface marker, L1CAM. RNA sequencing was performed. 12 FTD, 11 with AD, and 10 healthy aging participants were enrolled in the study. In FTD, SEV miRNA-181c was downregulated compared to healthy controls. In AD, miRNA-122 and miRNA-3591 were downregulated compared to those in healthy controls and FTD. Using an FDR <0.2, only miRNA-21-5p was found to have increased expression in the cerebrospinal fluid compared to plasma in a group of AD and FTD participants. SEV miRNA-181c is significantly downregulated in FTD compared to healthy controls and may mediate its effects through microglial-directed neuroinflammation and interaction with TAR DNA-binding protein 43 (TDP-43) based on pathway analysis. Additionally, the FOXO and Hippo pathways may be important mediators of FTD, based on pathway analysis. Lastly, because only one SEV miRNA was differentially expressed between the plasma and cerebrospinal fluid in paired samples, plasma represents an appropriate biofluid for studying neuronal SEV miRNA.

Transposable elements contribute to the spatiotemporal microRNA landscape in human brain development

Transposable elements (TEs) contribute to the evolution of gene regulatory networks and are dynamically expressed throughout human brain development and disease. One gene regulatory mechanism influenced by TEs is the miRNA system of post-transcriptional control. miRNA sequences frequently overlap TE loci and this miRNA expression landscape is crucial for control of gene expression in adult brain and different cellular contexts. Despite this, a thorough investigation of the spatiotemporal expression of TE-embedded miRNAs in human brain development is lacking. Here, we identify a spatiotemporally dynamic TE-embedded miRNA expression landscape between childhood and adolescent stages of human brain development. These miRNAs sometimes arise from two apposed TEs of the same subfamily, such as for L2 or MIR elements, but in the majority of cases stem from solo TEs. They give rise to in silico predicted high-confidence pre-miRNA hairpin structures, likely represent functional miRNAs, and have predicted genic targets associated with neurogenesis. TE-embedded miRNA expression is distinct in the cerebellum when compared to other brain regions, as has previously been described for gene and TE expression. Furthermore, we detect expression of previously nonannotated TE-embedded miRNAs throughout human brain development, suggestive of a previously undetected miRNA control network. Together, as with non-TE-embedded miRNAs, TE-embedded sequences give rise to spatiotemporally dynamic miRNA expression networks, the implications of which for human brain development constitute extensive avenues of future experimental research. To facilitate interactive exploration of these spatiotemporal miRNA expression dynamics, we provide the "Brain miRTExplorer" web application freely accessible for the community.

A new biomarker to enhance the radiosensitivity of hepatocellular cancer: miRNAs

Aims: This review summarizes findings regarding miRNAs that modulate radiation in hepatocellular carcinoma (HCC) and evaluates their potential clinical therapeutic uses. Materials & methods: We searched the relevant English-language medical databases for papers on miRNAs and radiation therapy for tumors to identify miRNAs that are linked with radiosensitivity and radioresistance, focusing on those associated with HCC radiation. Results: There were 88 papers assessed for miRNAs associated with tumor radiation, 56 of which dealt with radiosensitization, 21 with radioresistance and 11 with radiosensitization for HCC. Conclusion: Further work in this area would enable future evaluation of radiation responses and the potential use of miRNAs as therapeutic agents in HCC patients.

Microglia-induced autophagic death of neurons via IL-6/STAT3/miR-30d signaling following hypoxia/ischemia

BACKGROUND

There is a relationship between autophagy and the occurrence, maintenance, and progression of several neurodegenerative diseases. The activation of microglia after ischemia contributes to neuronal injury via proinflammatory cytokines and neurotoxic elements. The purpose of this study was to evaluate the function of autophagy in the microglia-mediated death of neuronal cells.

METHODS AND RESULTS

Microglial activation by oxygen/glucose deprivation induced both apoptosis and autophagy in neuron-like PC12 cells. Microglia-derived interleukin (IL)-6 induced PC12 cell apoptosis in vitro; however, this effect was inhibited by the autophagy inhibitor chloroquine. Further analysis demonstrated that miR-30d in PC12 cells suppressed microglia-induced PC12 apoptosis and autophagy by directly targeting autophagy protein 5. Moreover, microglia-derived IL-6 activated signal transducer and activator of transcription 3 (STAT3), which can then directly repress miR-30d genes via a conserved STAT3-binding site in its promoter, thereby promoting PC12 cell autophagy and apoptosis.

CONCLUSIONS

Our study identified IL-6-dependent autophagy-related signaling between microglia and neurons, which contributed to neuronal apoptosis. Importantly, we also provided potential therapeutic targets for ischemic treatment via the interruption of proinflammatory signaling.

Chlorogenic Acid Prevents Microglia-Induced Neuronal Apoptosis and Oxidative Stress under Hypoxia-Ischemia Environment by Regulating the MIR497HG/miR-29b-3p/SIRT1 Axis

Background

Chlorogenic acid (CGA) is a polyphenolic compound with antioxidant and anti-inflammatory properties. CGA has been shown to improve neuroinflammation. This study is aimed at elucidating the exact mechanism by which CGA reduces neuroinflammation.

Methods

Oxygen and glucose deprivation (OGD) was utilized to treat BV2 microglia and HT-22 hippocampal neurons to engineer an in vitro model of hypoxic ischemia reperfusion. The levels of inflammatory factors (IL-1β, IL-6, TNF-α, IL-4, and IL-10) and oxidative stress factors (MDA, SOD, and GSH-PX) in microglia were determined by ELISA kits. The neuron proliferation was assessed by CCK-8 assay, and LDH kit was used to determine LDH release in neurons. The fluorescent dye DCF-DA was employed to measure ROS levels in neurons. Correlation of MIR497HG, miR-29b-3p, and SIRT1/NF-κB in neurons and microglia was determined by qRT-PCR. Expressions of inflammatory proteins (COX2, iNOS), oxidative stress pathways (Nrf2, HO-1), and apoptosis-related proteins (Bcl-2, Bax, caspase3, caspase8, and caspase9) in microglia or neurons were determined by western blot. The interactions between MIR497HG and miR-29b-3p, as well as between miR-29b-3p and SIRT1, were determined by dual luciferase assay and RIP assay.

Results

CGA attenuated OGD-mediated inflammation and oxidative stress in microglia and inhibited microglia-mediated neuronal apoptosis. CGA increased the levels of MIR497HG and SIRT1 and suppressed the levels of miR-29b-3p in BV2 and HT-22 cells. MIR497HG knockdown, miR-29b-3p upregulation, and SIRT1 inhibition inhibited CGA-mediated anti-inflammatory and neuronal protective functions. There is a targeting correlation between MIR497HG, miR-29b-3p, and Sirt1. MIR497HG sponges miR-29b-3p to regulate SIRT1 expression in an indirect manner.

Conclusion

CGA upregulates MIR497HG to curb miR-29b-3p expression, hence initiating the SIRT1/NF-κB signaling pathway and repressing OGD-elicited inflammation, oxidative stress, and neuron apoptosis.

Dexmedetomidine attenuates oxygen-glucose deprivation/ reperfusion-induced inflammation through the miR-17-5p/ TLR4/ NF-κB axis

Background

Dexmedetomidine (DEX) is a selective agonist of α2-adrenergic receptors with anesthetic activity and neuroprotective benefits. However, its mechanism of action at the molecular level remains poorly defined. In this study, we investigated the protective effects of DEX on oxygen-glucose deprivation/ reperfusion (OGD/R)-induced neuronal apoptosis in PC12 cells, and evaluated its underlying mechanism(s) of neuroprotection and anti-inflammation.

Methods

An OGD/R model in PC12 cells was established. PC12 cells were cultured and divided into control, OGD/R, and OGD/R + DEX (1 μM, 10 μM, 50 μM) groups. Cell apoptosis was analyzed by flow cytometry and expression profiles were determined by qRT-PCR, western blot analysis, and enzyme linked immunosorbent assays (ELISA). The interaction between miRNA and its downstream targets was evaluated through luciferase reporter assays.

Results

DEX significantly decreased apoptosis rates and inhibited interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin 6 (IL-6) release (P < 0.05). While expression of the pro-apoptotic proteins Bax and Caspase-3 was down-regulated, expression of Bcl-2 was upregulated in a dose-dependent manner (P < 0.05). Interestingly, miR-17-5p expression was down-regulated in the OGD/R group (compared to controls). Toll-like receptor 4 (TLR4), a key regulator of nuclear factor kappa-B (NF-κB) signaling, was identified as a novel target of miR-17-5p in PC12 cells. miR-17-5p expression was upregulated in the OGD/R + DEX group, suppressing TLR4 expression and reducing the secretion of proinflammatory cytokines.

Conclusion

DEX inhibits OGD/R-induced inflammation and apoptosis in PC12 cells by increasing miR-17-5p expression, downregulating TLR4, and inhibiting NF-κB signaling.

MicroRNA-379-5p targets MAP3K2 to reduce autophagy and alleviate neuronal injury following cerebral ischemia via the JNK/c-Jun signaling pathway

MicroRNAs (miRNAs) are abundant in neurons and play key roles in the function and development of the nervous system. This study focuses on the function of miR-379-5p in neurological function recovery during ischemic stroke. The expression of miR-379-5p in the serum of patients with ischemic stroke was determined. Human cerebral cortical neuron cells (HCN-2) were subjected to oxygen/glucose deprivation (OGD) to mimic an ischemic stroke in vitro, whereas mice subjected to middle cerebral artery occlusion (MCAO) were used as an animal model. The serum of patients with ischemic stroke and OGD-treated HCN-2 cells displayed a poor expression of miR-379-5p. Upregulation of miR-379-5p reduced the OGD-induced cell damage and decreased the expression of the autophagy marker protein Beclin1 in cells. Rapamycin, an autophagy activator, blocked the protective functions of miR-379-5p. Further, miR-379-5p directly bound to MAP3K2. MAP3K2 activated the JNK/c-Jun signaling pathway and suppressed the neuroprotective events mediated by miR-379-5p. The in vitro results were reproduced in vivo, where upregulation of miR-379-5p reduced neurological impairment and infarct size in MCAO-induced mice. This study suggested that miR-379-5p showed a neuroprotective effect on ischemic stroke and reduced autophagy of neurons through the suppression of MAP3K2 and the JNK/c-Jun axis.

Non-Coding RNAs Based Molecular Links in Type 2 Diabetes, Ischemic Stroke, and Vascular Dementia

This article reviews recent advances in the study of microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and their functions in type 2 diabetes mellitus (T2DM), ischemic stroke (IS), and vascular dementia (VaD). miRNAs and lncRNAs are gene regulation markers that both regulate translational aspects of a wide range of proteins and biological processes in healthy and disease states. Recent studies from our laboratory and others have revealed that miRNAs and lncRNAs expressed differently are potential therapeutic targets for neurological diseases, especially T2DM, IS, VaD, and Alzheimer's disease (AD). Currently, the effect of aging in T2DM, IS, and VaD and the cellular and molecular pathways are largely unknown. In this article, we highlight results from the works on the molecular connections between T2DM and IS, and IS and VaD. In each disease, we also summarize the pathophysiology and the differential expressions of miRNAs and lncRNAs. Based on current research findings, we hypothesize that 1) T2DM bi-directionally and age-dependently induces IS and VaD, and 2) these changes are precursors to the onset of dementia in elderly people. Research into these hypotheses is required to examine further whether research efforts on reducing T2DM, IS, and VaD may affect dementia and/or delay the AD disease process in the aged population.

CircPTK2-miR-181c-5p-HMGB1: a new regulatory pathway for microglia activation and hippocampal neuronal apoptosis induced by sepsis

BACKGROUND

Circular RNA hsa_circ_0008305 (circPTK2), miR-181c-5p and High mobility group box-1 (HMGB1) had a targeted regulatory relationship through bioinformatics analysis. This study explained the effects of these genes in microglia and sepsis mice.

METHODS

Lipopolysaccharide (LPS) or Cecal Ligation and Puncture (CLP) was used to induce inflammation cell model or sepsis mouse model, as needed. Gene levels were measured by enzyme linked immunosorbent assay (ELISA), quantitative real-time PCR or Western blot, as required. Apoptosis was detected by TUNEL assay, and RNase R was used to test the stability of circPTK2. Targeting relationships between genes were analyzed using bioinformatics analysis and dual luciferase assay. Morris water maze test and mitochondrial membrane potential (MMP) detection were conducted to analyze the effects of genes on cognitive dysfunction of mice.

RESULTS

Lipopolysaccharide induction triggered the release of pro-inflammatory cytokines, the upregulation of HMGB1 and circPTK2, and the downregulation of miR-181c-5p in microglia. Overexpression of HMGB1 enhanced the effect of LPS, while silencing HMGB1 partially counteracted the effect of LPS. Moreover, miR-181c-5p was a target of circPTK2 and bound to HMGB1. MiR-181c-5p mimic partially reversed the functions of LPS and HMGB1 overexpression, reduced the levels of TNF-α, IL-1β, and HMGB1, and inhibited apoptosis. CircPTK2 knockdown had the same effect as miR-181c-5p up-regulation. In vivo, sicircPTK2 improved cognitive function, restored MMP level, inhibited apoptosis, reduced the levels of inflammatory factors and apoptotic factors, and increased the survival rate of CLP-induced mice.

CONCLUSION

Our research reveals that circPTK2 regulates microglia activation and hippocampal neuronal apoptosis induced by sepsis via miR-181c-5p-HMGB1 signaling.

Epigenetics and Communication Mechanisms in Microglia Activation with a View on Technological Approaches

Microglial cells, the immune cells of the central nervous system (CNS), play a crucial role for the proper brain development and function and in CNS homeostasis. While in physiological conditions, microglia continuously check the state of brain parenchyma, in pathological conditions, microglia can show different activated phenotypes: In the early phases, microglia acquire the M2 phenotype, increasing phagocytosis and releasing neurotrophic and neuroprotective factors. In advanced phases, they acquire the M1 phenotype, becoming neurotoxic and contributing to neurodegeneration. Underlying this phenotypic change, there is a switch in the expression of specific microglial genes, in turn modulated by epigenetic changes, such as DNA methylation, histones post-translational modifications and activity of miRNAs. New roles are attributed to microglial cells, including specific communication with neurons, both through direct cell–cell contact and by release of many different molecules, either directly or indirectly, through extracellular vesicles. In this review, recent findings on the bidirectional interaction between neurons and microglia, in both physiological and pathological conditions, are highlighted, with a focus on the complex field of microglia immunomodulation through epigenetic mechanisms and/or released factors. In addition, advanced technologies used to study these mechanisms, such as microfluidic, 3D culture and in vivo imaging, are presented.

Hypoxia-Induced S100A8 Expression Activates Microglial Inflammation and Promotes Neuronal Apoptosis

S100 calcium-binding protein A8 (S100A8), a danger-associated molecular pattern, has emerged as an important mediator of the pro-inflammatory response. Some S100 proteins play a prominent role in neuroinflammatory disorders and increase the secretion of pro-inflammatory cytokines in microglial cells. The aim of this study was to determine whether S100A8 induced neuronal apoptosis during cerebral hypoxia and elucidate its mechanism of action. In this study, we reported that the S100A8 protein expression was increased in mouse neuronal and microglial cells when exposed to hypoxia, and induced neuroinflammation and neuronal apoptosis. S100A8, secreted from neurons under hypoxia, activated the secretion of tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) through phosphorylation of extracellular-signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) in microglia. Also, phosphorylation of ERK via the TLR4 receptor induced the priming of the NLRP3 inflammasome. The changes in Cyclooxygenase-2 (COX-2) expression, a well-known inflammatory activator, were regulated by the S100A8 expression in microglial cells. Knockdown of S100A8 levels by using shRNA revealed that microglial S100A8 expression activated COX-2 expression, leading to neuronal apoptosis under hypoxia. These results suggested that S100A8 may be an important molecule for bidirectional microglia-neuron communication and a new therapeutic target for neurological disorders caused by microglial inflammation during hypoxia.

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.

Hypoxic naked mole-rat brains use microRNA to coordinate hypometabolic fuels and neuroprotective defenses

Naked mole-rats are among the mammalian champions of hypoxia tolerance. They evolved adaptations centered around reducing metabolic rate to overcome the challenges experienced in their underground burrows. In this study, we used next-generation sequencing to investigate one of the factors likely supporting hypoxia tolerance in naked mole-rat brains, posttranscriptional microRNAs (miRNAs). Of the 212 conserved miRNAs identified using small RNA sequencing, 18 displayed significant differential expression during hypoxia. Bioinformatic enrichment revealed that hypoxia-mediated miRNAs were suppressing energy expensive processes including de novo protein translation and cellular proliferation. This suppression occurred alongside the activation of neuroprotective and neuroinflammatory pathways, and the induction of central signal transduction pathways including HIF-1α and NFκB via miR-335, miR-101, and miR-155. MiRNAs also coordinated anaerobic glycolytic fuel sources, where hypoxia-upregulated miR-365 likely suppressed protein levels of ketohexokinase, the enzyme responsible for catalyzing the first committed step of fructose catabolism. This was further supported by a hypoxia-mediated reduction in glucose transporter 5 proteins that import fructose into the cell. Yet, messenger RNA and protein levels of lactate dehydrogenase, which converts pyruvate to lactate in the absence of oxygen, were elevated during hypoxia. Together, this demonstrated the induction of anaerobic glycolysis despite a lack of reliance on fructose as the primary fuel source, suggesting that hypoxic brains are metabolically different than anoxic naked mole-rat brains that were previously found to shift to fructose-based glycolysis. Our findings contribute to the growing body of oxygen-responsive miRNAs "OxymiRs" that facilitate natural miRNA-mediated mechanisms for successful hypoxic exposures.

MicroRNA regulation in hypoxic environments: differential expression of microRNAs in the liver of largemouth bass (Micropterus salmoides)

Environmental changes in intensive aquaculture commonly lead to hypoxic stress for cultured largemouth bass (Micropterus salmoides). To better to understand the hypoxic stress response mechanisms, the miRNA expression profiles of the livers of largemouth bass exposed for 24 h to three different dissolved oxygen levels (7.0 ± 0.2 mg/L as control, 3.0 ± 0.2 mg/L and 1.2 ± 0.2 mg/L) were compared. In this study, a total of 266 known miRNAs were identified, 84 of which were differentially expressed compared with the control group. Thirteen of the differentially expressed miRNAs (miR-15b-5p, miR-30a-3p, miR-133a-3p, miR-19d-5p, miR-1288-3p, miR456, miR-96-5p, miR-23a-3p, miR-23b-5p, miR-214, miR-24, miR-20a-3p, and miR-2188-5p) were significantly enriched in VEGF signaling pathway, MAPK signaling pathway, and phosphatidylinositol signaling system. These miRNAs were significantly downregulated during stress, especially after a 4-h exposure to hypoxia. In contrast, their target genes (vegfa, pla2g4a, raf1a, pik3c2a, clam2a, inpp1, pi4k2b, mtmr14, ip6k, itpkca, map3k7, and Jun) were significant upregulated after 4 h of hypoxic stress. Moreover, two potential hypoxia-tolerance signal transduction pathways (MAPK signaling pathway and phosphatidylinositol signaling system) were revealed, both of which may play important roles in responding to acute hypoxic stress. We see that miRNAs played an important role in regulating gene expression related to physiological responses to hypoxia. Potential functional network regulated by miRNAs under hypoixic stress in the liver of largemouth bass (Micropterus salmoides). Blue boxes indicated that the expression of miRNA or target genes were down-regulated. Red boxes indicated that the expression of miRNA or target genes wasere up-regulated.

Toll-Like Receptor Signaling in Depression

Depression is one of the most prevalent, disabling, and costly mental illnesses currently affecting over 300 million people worldwide. A subset of depressed patients display inflammation as indicated by increased levels of proinflammatory mediators in the blood and cerebrospinal fluid. Longitudinal and experimental studies suggest that this inflammatory profile may causally contribute to the initiation, maintenance, or recurrence of depressive episodes in the context of major depressive disorder (MDD). While the mechanistic pathways that mediate these depressogenic effects have not yet been fully elucidated, toll-like receptor (TLR) signaling is one potential common inflammatory pathway. In this review, we focus on the role that inflammation plays in depression, TLR signaling and its plasticity as a candidate pathway, its regulation by micro ribonucleic acids (miRNAs), and their potential as diagnostic biomarkers for identification of inflammatory subtypes of depression. Pre-clinical and clinical studies have demonstrated that TLR expression and TLR signaling regulators are associated with MDD. Further, TLR expression and signaling is in-turn, regulated in part by miRNAs and some TLR-responsive miRNAs indirectly modulate pathways that are implicated in MDD pathophysiology. These data suggest an intersection between TLR signaling regulation and MDD-linked pathways. While these studies suggest that miRNAs play a role in the pathophysiology of MDD via their regulatory effects on TLR pathways, the utility of miRNAs as biomarkers and potential treatment targets remains to be determined. Developing new and innovative techniques or adapting established immunological approaches to mental health, should be at the forefront in moving the field forward, especially in terms of categorization of inflammatory subtypes in MDD.

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.

MiR-181c-5p Promotes Inflammatory Response during Hypoxia/Reoxygenation Injury by Downregulating Protein Tyrosine Phosphatase Nonreceptor Type 4 in H9C2 Cardiomyocytes

Background

Constitutive nuclear factor kappa B (NFκB) activation has been shown to exacerbate during myocardial ischemia/reperfusion (I/R) injury. We recently showed that miR-181c-5p exacerbated cardiomyocytes injury and apoptosis by directly targeting the 3′-untranslated region of protein tyrosine phosphatase nonreceptor type 4 (PTPN4). However, whether miR-181c-5p mediates cardiac I/R injury through NFκB-mediated inflammation is unknown. Thus, the present study aimed to investigate the role of miR-181c-5p during myocardial I/R injury and explore its mechanism in relation to inflammation in H9C2 cardiomyocytes.

Methods and Results

In hypoxia/reoxygenation (H/R, 6 h hypoxia followed by 6 h reoxygenation)-stimulated H9C2 cardiomyocytes or postischemic myocardium of rat, the expression of miR-181c-5p was significantly upregulated, which was concomitant increased NFκB activity when compared to the nonhypoxic or nonischemic control groups. This is indicative that miR-181c-5p may be involved in NFκB-mediated inflammation during myocardial I/R injury. To investigate the potential role of miR-181c-5p in H/R-induced cell inflammation and injury, H9C2 cardiomyocytes were transfected with the miR-181c-5p agomir. Overexpression of miR-181c-5p significantly aggravated H/R-induced cell injury (increased lactate dehydrogenase (LDH) level) and exacerbated NFκB-mediated inflammation (greater phosphorylation and degradation of IκBα, phosphorylation of p65, and increased levels of proinflammatory cytokines tumor necrosis factor α (TNFα), interleukin (IL)-6, and IL-1β). In contrast, inhibition of miR-181c-5p by its antagomir transfection in vitro had the opposite effect. Furthermore, overexpression of miR-181c-5p significantly enhanced lipopolysaccharide-induced NFκB signalling. Additionally, knockdown of PTPN4, the direct target of miR-181c-5p, significantly aggravated H/R-induced phosphorylation and degradation of IκBα, phosphorylation of p65, and the levels of proinflammatory cytokines. PTPN4 knockdown also cancelled miR-181c-5p antagomir mediated anti-inflammatory effects in H9C2 cardiomyocytes during H/R injury.

Conclusions

It is concluded that miR-181c-5p may exacerbate myocardial I/R injury and NFκB-mediated inflammation via PTPN4, and that targeting miR-181c-5p/PTPN4/NFκB signalling may represent a novel strategy to combat myocardial I/R injury.

MicroRNA-381-3p Functions as a Dual Suppressor of Apoptosis and Necroptosis and Promotes Proliferation of Renal Cancer Cells

Renal cell carcinoma (RCC) is the most common type of kidney cancer. It has a poor prognosis, with approximately 20-30% of patients developing recurrent and/or metastatic diseases that is relatively high resistant to conventional therapy. Resisting cell death is a hallmark of cancer cells. Apoptosis is a form of programmed cell death mediated by the activation of caspases. Necroptosis is a form of regulated necrosis that relies on the activation of receptor-interacting protein kinase 1 (RIPK1), RIPK3 and mixed lineage kinase domain-like protein (MLKL), the substrate of RIPK3. Cancer cells often display apoptosis resistance via upregulation of anti-apoptotic genes and defective necroptosis due to the epigenetic silence of Ripk3. MicroRNAs (miRNAs) are non-coding small RNAs that are involved in numerous biological processes including cell proliferation, differentiation and death. In this study, we screened a set of ∼120 miRNAs for apoptosis-regulating miRNAs and identified miR-381-3p as a suppressor of TNF-induced apoptosis in various cancer cells. Ectopic expression of miR-381-3p inhibits the activation of caspase-8 and caspase-3. The expression level of miR-381-3p inversely correlates with the sensitivity of cancer cells to TNF-induced apoptosis. Moreover, we found that overexpression of miR-381-3p blocks TNF-induced necroptosis by inhibiting the activation of RIPK3 and MLKL. Of note, Kaplan-Meier Plotter analysis demonstrates that papillary RCC patients with high miR-381-3p expression have a lower overall survival than those with low expression level of miR-381-3p. Importantly, miR-381-3p overexpression promotes colony formation in human renal cancer cells. Thus, miR-381-3p acts as an oncogenic miRNA that counteracts both apoptotic and necroptotic signaling pathways. Our findings highlight miR-381-3p as a biomarker for predicting sensitivity to apoptosis and necroptosis, and as a possible therapeutic target for RCC.

δ-Opioid Receptors, microRNAs, and Neuroinflammation in Cerebral Ischemia/Hypoxia

Hypoxia and ischemia are the main underlying pathogenesis of stroke and other neurological disorders. Cerebral hypoxia and/or ischemia (e.g., stroke) can lead to neuronal injury/death and eventually cause serious neurological disorders or even death in the patients. Despite knowing these serious consequences, there are limited neuroprotective strategies against hypoxic and ischemic insults in clinical settings. Recent studies indicate that microRNAs (miRNAs) are of great importance in regulating cerebral responses to hypoxic/ischemic stress in addition to the neuroprotective effect of the δ-opioid receptor (DOR). Moreover, new discovery shows that DOR can regulate miRNA expression and inhibit inflammatory responses to hypoxia/ischemia. We, therefore, summarize available data in current literature regarding the role of DOR and miRNAs in regulating the neuroinflammatory responses in this article. In particular, we focus on microglia activation, cytokine production, and the relevant signaling pathways triggered by cerebral hypoxia/ischemia. The intent of this review article is to provide a novel clue for developing new strategies against neuroinflammatory injury resulting from cerebral hypoxia/ischemia.

Radiosensitization of Hepatocellular Carcinoma through Targeting Radio-Associated MicroRNA

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related deaths worldwide. For patients who are resistant to monotherapy, multimodal therapy is a basic oncologic principle that incorporates surgery, radiotherapy (RT), and chemotherapy providing survival benefits for patients with most types of cancer. Although liver has low tolerance for radiation, high-precision RT for local HCC minimizes the likelihood of radiation-induced liver disease (RILD) in noncancerous liver tissue. RT have several therapeutic benefits, including the down-staging of tumors to make them resectable and repression of metastasis. The DNA damage response (DDR) is a cellular response to irradiation (IR), including DNA repair of injured cells and induction of programmed cell death, thereby resulting in maintenance of cell homeostasis. Molecules that block the activity of proteins in DDR pathways have been found to enhance radiotherapeutic effects. These molecules include antibodies, kinase inhibitors, siRNAs and miRNAs. MicroRNAs (miRNAs) are short non-coding regulatory RNAs binding to the 3'-untranslated regions (3'-UTR) of the messenger RNAs (mRNAs) of target genes, regulating their translation and expression of proteins. Thus, miRNAs and their target genes constitute complicated interactive networks, which interact with other molecules during carcinogenesis. Due to their promising roles in carcinogenesis, miRNAs were shown to be the potential factors that mediated radiosensitivity and optimized outcomes of the combination of systemic therapy and radiotherapy.

Micro RNA 181c-5p: A promising target for post-stroke recovery in socially isolated mice

Dysregulation of microRNAs (miRNAs) has been tied to several neurological disorders, including ischemic stroke. It has also been established that social environments can modulate miRNA profiles. We have previously shown that post-stroke social isolation (SI) is linked to poor stroke outcomes and that miR-181c-5p emerged as one of few lead miRNAs that was downregulated in both stroke and SI. Therefore, in this study we examined the potential role of miR-181c-5p mimic in reversing the detrimental effects of post-stroke SI. Two to three-month-old C57BL/6 male mice were pair-housed (PH) for at least two weeks. After two weeks, mice underwent stroke survival surgery using middle cerebral artery occlusion (MCAO) and were randomly assigned to one of two housing conditions: stroke isolation (ST-ISO) or stroke pair-housing with a healthy partner (ST-PH). ST-ISO mice were randomized to receive either miR-181c-5p mimic or a scrambled RNA (7 mg/kg i.v./day×drug) control at 24 h and 48 h after stroke. The effects of miR-181c-5p mimic treatment were evaluated at 1, 3, and 7 days after stroke at histological, behavioral, and biochemical levels. Target genes of miR-181c-5p were then analyzed by qPCR using an RT2 Profiler qPCR Array of pre-coated miR-181c gene targets. Temporal profile expression data suggested that miR-181c-5p was significantly downregulated (p < 0.05 vs ST-PH) up to 7 days after post-stroke SI. MiR-181c-5p mimic treatment significantly increased miR-181c-5p expression in brain tissue and showed partial swift recovery in sensorimotor deficit. Target gene analysis identified downregulation of several calcium signaling-related genes, e.g., Cpne2 and Gria 1 & 2 after miR-181c-5p mimic treatment. In summary, present data suggests that miR-181c-5p is a potential target for post-stroke SI. Data also suggests that genes related to calcium and glutamate signaling might be involved in the beneficial effect of the miR-181c-5p mimic.

Methamphetamine-induced alterations in intestinal mucosal barrier function occur via the microRNA-181c/ TNF-α/tight junction axis

An enterogenic infection occurs when intestinal mucosal disruption is followed by the invasion of intestinal bacteria into the blood and distant organs, which can result in severe diseases or even death. Our previous study using Rhesus monkeys as an in vivo model revealed that methamphetamine (MA) induced intestinal mucosal barrier damage, which poses a high risk of enterogenic infection. However, how methamphetamine causes intestinal mucosal barrier damage remains largely unknown. In this study, we employed an in vitro model, and found that MA treatment could inhibit the expression of miR-181c, which directly targets and regulates TNF-α, and ultimately induces apoptosis and damages the intestinal barrier. Moreover, we measured TNF-α serum levels as well as the intestinal mucosal barrier damage indicators (diamine oxidase, d-lactic acid, and exotoxin) and found that their levels were significantly higher in MA-dependents than in healthy controls (P < 0.001). To the best of our knowledge, this is the first report evidencing that miR-181c is involved in MA-induced intestinal barrier injury via TNF-α regulation, which introduces novel potential therapeutic targets for MA-dependent intestinal diseases.

Exosomal miR-451 from human umbilical cord mesenchymal stem cells attenuates burn-induced acute lung injury

BACKGROUND

The aim of this study was to investigate the molecular mechanism of human umbilical cord mesenchymal stem cells (MSCs)-derived exosomes (hUCMSC-Exos) in regulating burn-induced acute lung injury (ALI).

METHODS

In this study, we initially isolated exosomes from hUCMSCs and identified them by transmission electron microscopy. The expression of the protein markers CD9 and CD63 in the exosomes was determined by western blot analysis. The expression of miR-451 in the hUCMSC-Exos was determined by qRT-PCR. The levels of TNF-α, IL-1β, and IL-6 in lung tissues and serum as well as the levels of malondialdehyde, myeloperoxidase, superoxide dismutase in lung tissues were detected by ELISA. Hematoxylin-eosin stain was used to observe the morphological changes of lung tissues after burn. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assays were performed to detect apoptosis in lung tissues after burn. The expression of proteins related to the Toll-like receptor 4 (TLR4)/NF-κB signaling pathway in lung tissues after burn was analyzed by western blotting.

RESULTS

Our results showed that hUCMSC-Exos successfully decreased TNF-α, IL-1β, and IL-6 levels in rats after burn, and this reduction was reversed when the miR-451 expression in the hUCMSC-Exo group was inhibited. HUCMSC-Exo-derived miR-451 improves ALI via the TLR4/NF-κB pathway.

CONCLUSION

We demonstrated that exosomes derived from hUCMSCs mediate miR-451 to attenuate burn-induced ALI.

Cortical Neuron-Derived Exosomal MicroRNA-181c-3p Inhibits Neuroinflammation by Downregulating CXCL1 in Astrocytes of a Rat Model with Ischemic Brain Injury

OBJECTIVES

Cortical neuron-released exosomes have been demonstrated to block inflammasome activation in the central nervous system. This study aimed to investigate whether cortical neuron-released exosomal microRNA-181c-3p (miR-181c-3p) affected ischemic brain injury (IBI).

METHODS

An IBI rat model was established by middle cerebral artery occlusion (MCAO). Astrocytes collected from rats were exposed to exosomes derived from cortical neurons to investigate the effect of exosomes on chemokine (C-X-C motif) ligand 1 (CXCL1) expression and inflammatory response. Then, ectopic expression was induced in astrocytes treated with oxygen and glucose deprivation (OGD).

RESULTS

CXCL1 was identified to be an upregulated gene in IBI by microarray-based gene expression profiling. Additionally, upregulation of CXCL1 and promoted inflammatory response was also found in MCAO rats. miR-181c-3p was downregulated in OGD-treated cortical neurons and exosomes derived from OGD-treated cortical neurons. Exosomes derived from OGD-treated cortical neurons decreased the expression of CXCL1 and inflammatory factors in astrocytes, and exosomes delivered miR-181c-3p to decrease CXCL1 expression in astrocytes. CXCL1 was a target gene of miR-181c-3p. Delivery with miR-181c-3p mimic and siRNA against CXCL1 (si-CXCL1) was shown to inhibit inflammation in astrocytes by downregulating CXCL1.

CONCLUSION

Collectively, exosomal miR-181c-3p derived from cortical neurons exerts protective effects on neuroinflammation in astrocytes via downregulation of CXCL1 in an IBI rat model.

Silencing interleukin 1α underlies a novel inhibitory role of miR-181c-5p in alleviating low-grade inflammation of rats with irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common disorder of unknown etiology. Studies have found a close relation between IBS and microRNAs (miRNAs), but the study concerning the relationship between IBS and miR-181c-5p in IBS is still blank. Thus, this study aims to explore the role of miR-181c-5p in IBS via interleukin 1α (IL1A). Initially, microarray analysis was used to retrieve the genes related to IBS and to predict miRNAs regulating IL1A gene. IBS model was then established with abdominal withdraw reflection (AWR) and Bristol stool grading in mice measured. Afterwards, the functional role of miR-181c-5p in IBS was determined using the ectopic expression, depletion and reporter assay experiments, as well as miR-181c-5p and IL1A expression detected. Subsequently, expression of tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), and IL-6 were detected to further determine the effects of miR-181c-5p and IL1A on inflammation in IBS. miR-181c-5p and IL1A might be involved in IBS. miR-181c-5p was found to be decreased while IL1A was increased in IBS rats. In addition, miR-181c-5p could target and inhibit expression of IL1A, and IBS mice exhibited elevated AWR and Bristol stool grading, namely 6 to 7 points (70.4 [38 of 54]). Moreover, with the overexpression of miR-181c-5p or silencing of IL1A, the expression of TNF-α, IL-2, and IL-6 was decreased. Collectively, this study suggested that overexpressed miR-181c-5p could silence IL1A, thus inhibiting low-grade inflammation in IBS rats. miR-181c-5p/IL1A is expected to serve as a novel target for the treatment of IBS.

Screening the Action Targets of Enterovirus 71 in Human SH-SY5Y Cells Using RNA Sequencing Data

Hand, foot, and mouth disease (HFMD) is a common infection for children younger than the age of five. HFMD is mainly induced by coxsackievirus A16 and enterovirus 71 (EV71). EV71-associated HFMD often has serious neurological disease complications. The purpose of this study was to reveal the mechanisms of action of EV71 on neurons. SH-SY5Y cells transfected or untransfected with EV71 were sequenced. After data preprocessing, differentially expressed genes (DEGs) were screened using the limma package in R, and clustering analysis was then performed using the ComplexHeatmap package in R. The DAVID tool was used for EDG enrichment analysis. Protein-protein interactions (PPIs) were predicted using the STRING database and PPI networks were then constructed using Cytoscape software. After pathways involved in the key PPI network nodes were enriched, pathway deviation scores were calculated. Clustering analysis was also conducted for these pathways. There were 978 DEGs in the transfected samples. Upregulated TNF was enriched in NF-kappa B signaling pathway. Among the top 20 nodes in the PPI network, CDK1, STAT3, CCND1, TNF, and MYC had the highest degrees. A total of 28 pathways were enriched for the top 20 nodes, including Epstein-Barr virus infection (p = 3.78E-06), proteoglycans in cancer (p = 4.96E-06), and melanoma (p = 1.99E-05). In addition, clustering analysis showed that these pathways could clearly differentiate the two groups of samples. EV71 may affect neurons by mediating CDK1, STAT3, CCND1, TNF, and MYC, indicating that these genes are promising targets for preventing the neuronal complications of HFMD.

MicroRNA-181c Inhibits Interleukin-6-mediated Beta Cell Apoptosis by Targeting TNF-α Expression

We have previously reported that long-term treatment of beta cells with interleukin-6 (IL-6) is pro-apoptotic. However, little is known about the regulatory mechanisms that are involved. Therefore, we investigated pro-apoptotic changes in mRNA expression in beta cells in response to IL-6 treatment. We analyzed a microarray with RNA from INS-1 beta cells treated with IL-6, and found that TNF-α mRNA was significantly upregulated. Inhibition of TNF-α expression by neutralizing antibodies significantly decreased annexin V staining in cells compared with those treated with a control antibody. We identified three microRNAs that were differentially expressed in INS-1 cells incubated with IL-6. In particular, miR-181c was significantly downregulated in IL-6-treated cells compared with control cells and the decrease of miR-181c was attenuated by STAT-3 signaling inhibition. TNF-α mRNA was a direct target of miR-181c and upregulation of miR-181c by mimics, inhibited IL-6-induced increase in TNF-α mRNA expression. Consequently, reduction of TNF-α mRNA caused by miR-181c mimics enhanced cell viability in IL-6 treated INS-1 cells. These results demonstrated that miR-181c regulation of TNF-α expression plays a role in IL-6-induced beta cell apoptosis.

MicroRNAs and the Genetic Nexus of Brain Aging, Neuroinflammation, Neurodegeneration, and Brain Trauma

Aging is a complex and integrated gradual deterioration of cellular activities in specific organs of the body, which is associated with increased mortality. This deterioration is the primary risk factor for major human pathologies, including cancer, diabetes, cardiovascular disorders, neurovascular disorders, and neurodegenerative diseases. There are nine tentative hallmarks of aging. In addition, several of these hallmarks are increasingly being associated with acute brain injury conditions. In this review, we consider the genes and their functional pathways involved in brain aging as a means of developing new strategies for therapies targeted to the neuropathological processes themselves, but also as targets for many age-related brain diseases. A single microRNA (miR), which is a short, non-coding RNA species, has the potential for targeting many genes simultaneously and, like practically all other cellular processes, genes associated with many features of brain aging and injury are regulated by miRs. We highlight how certain miRs can mediate deregulation of genes involved in neuroinflammation, acute neuronal injury and chronic neurodegenerative diseases. Finally, we review the recent progress in the development of effective strategies to block specific miR functions and discuss future approaches with the prediction that anti-miR drugs may soon be used in the clinic.

Placenta-Derived Cells for Acute Brain Injury

Acute brain injury resulting from ischemic/hemorrhagic or traumatic damage is one of the leading causes of mortality and disability worldwide and is a significant burden to society. Neuroprotective options to counteract brain damage are very limited in stroke and traumatic brain injury (TBI). Given the multifaceted nature of acute brain injury and damage progression, several therapeutic targets may need to be addressed simultaneously to interfere with the evolution of the injury and improve the patient’s outcome. Stem cells are ideal candidates since they act on various mechanisms of protection and repair, improving structural and functional outcomes after experimental stroke or TBI. Stem cells isolated from placenta offer advantages due to their early embryonic origin, ease of procurement, and ethical acceptance. We analyzed the evidence for the beneficial effects of placenta-derived stem cells in acute brain injury, with the focus on experimental studies of TBI and stroke, the engineering strategies pursued to foster cell potential, and characterization of the bioactive molecules secreted by placental cells, known as their secretome, as an alternative cell-free strategy. Results from the clinical application of placenta-derived stem cells for acute brain injury and ongoing clinical trials are summarily discussed.

HMG-CoA Reductase Inhibitors Attenuate Neuronal Damage by Suppressing Oxygen Glucose Deprivation-Induced Activated Microglial Cells

Ischemic stroke is usually followed by inflammatory responses mediated by microglia. However, the effect of statins on directly preventing posthypoxia microglia inflammatory factors to prevent injury to surrounding healthy neurons is unclear. Atorvastatin and rosuvastatin, which have different physical properties regarding their lipid and water solubility, are the most common HMG-CoA reductase inhibitors (statins) and might directly block posthypoxia microglia inflammatory factors to prevent injury to surrounding neurons. Neuronal damage and microglial activation of the peri-infarct areas were investigated by Western blotting and immunofluorescence after 24 hours in a middle cerebral artery occlusion (MCAO) rat model. The decrease in neurons was in accordance with the increase in microglia, which could be reversed by both atorvastatin and rosuvastatin. The effects of statins on blocking secretions from posthypoxia microglia and reducing the secondary damage to surrounding normal neurons were studied in a coculture system in vitro. BV2 microglia were cultured under oxygen glucose deprivation (OGD) for 3 hours and then cocultured following reperfusion for 24 hours in the upper wells of transwell plates with primary neurons being cultured in the bottom wells. Inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and cyclooxygenase-2 (COX2), which are activated by the nuclear factor-kappa B (NF-κB) signaling pathway in OGD-induced BV2 microglia, promoted decreased release of the anti-inflammatory cytokine IL-10 and apoptosis of neurons in the coculture systems according to ELISA and Western blotting. However, pretreatment with atorvastatin or rosuvastatin significantly reduced neuronal death, synaptic injury, and amyloid-beta (Aβ) accumulation, which might lead to increased low-density lipoprotein receptors (LDLRs) in BV2 microglia. We concluded that the proinflammatory mediators released from postischemia damage could cause damage to surrounding normal neurons, while HMG-CoA reductase inhibitors prevented neuronal apoptosis and synaptic injury by inactivating microglia through blocking the NF-κB signaling pathway.

Circular RNA circPTK2 regulates oxygen-glucose deprivation-activated microglia-induced hippocampal neuronal apoptosis via miR-29b-SOCS-1-JAK2/STAT3-IL-1β signaling

Oxygen-glucose deprivation (OGD)-activated microglia contribute to neuronal apoptosis via releasing pro-inflammatory cytokines, and some miRNAs have been reported to be involved in this process. Circular RNAs (circRNAs) have been reported to function as miRNA sponges, but it remains unknown whether and how circRNAs contribute to OGD-activated microglia-induced neuronal apoptosis. Here, we investigated the function and relationship of miR-29b and circPTK2 in OGD-activated microglia-induced neuronal apoptosis. We found upregulation of TNF-α and IL-1β, and downregulation of miR-29b in OGD-activated microglia. miR-29b inhibited OGD-activated microglia-induced neuronal apoptosis. Meanwhile, miR-29b promoted SOCS-1 expression, and suppressed JAK2/STAT3 signaling. In addition, inhibition of JAK2/STAT3 signaling downregulated IL-1β expression, while upregulation of miR-29b or SOCS-1 also inhibited IL-1β production. IL-1β was confirmed to be an apoptosis inducer of hippocampal neurons. Moreover, either SOCS-1 upregulation or blockade of JAK2/STAT3 signaling suppressed OGD-activated microglia-induced neuronal apoptosis. These data suggest that miR-29b inhibits OGD-activated microglia-induced neuronal apoptosis via inducing SOCS-1 expression, blocking JNK2/STAT3 signaling, and inhibiting IL-1β production. circPTK2 was confirmed to inhibit miR-29b expression in OGD model by directly binding to miR-29b. Function assay showed that circPTK2 regulated microglia-induced neuronal apoptosis via sponging miR-29b. Collectively, these findings suggest that circPTK2 regulates OGD-activated microglia-induced neuronal apoptosis via miR-29b-SOCS-1-JAK2/STAT3-IL-1β signaling.