miR-9 Upregulation Integrates Post-ischemic Neuronal Survival and Regeneration In Vitro

Stereotactically intracerebral transplantation of neural stem cells for ischemic stroke attenuated inflammatory responses and promoted neurogenesis: an experimental study with monkeys

BACKGROUND

Ischemic stroke is a common neurovascular disorder with high morbidity and mortality. However, the underlying mechanism of stereotactically intracerebral transplantation of human neural stem cells (hNSCs) is not well elucidated.

MATERIALS AND METHODS

Four days after ischemic stroke induced by Rose Bengal photothrombosis, seven cynomolgus monkeys were transplanted with hNSCs or vehicles stereotactically and followed up for 84 days. Behavioral assessments, magnetic resonance imaging, blood tests, and pathological analysis were performed before and after treatment. The proteome profiles of the left and right precentral gyrus and hippocampus were evaluated. Extracellular vesicle micro-RNA (miRNA) from the peripheral blood was extracted and analyzed.

RESULTS

hNSC transplantation reduced the remaining infarcted lesion volume of cynomolgus monkeys with ischemic stroke without remarkable side effects. Proteomic analyses indicated that hNSC transplantation promoted GABAergic and glutamatergic neurogenesis and restored the mitochondrial electron transport chain function in the ischemic infarcted left precentral gyrus or hippocampus. Immunohistochemical staining and quantitative real-time reverse transcription PCR confirmed the promoting effects on neurogenesis and revealed that hNSCs attenuated post-infarct inflammatory responses by suppressing resident glia activation and mediating peripheral immune cell infiltration. Consistently, miRNA-sequencing revealed the miRNAs that were related to these pathways were downregulated after hNSC transplantation.

CONCLUSIONS

This study indicates that hNSCs can be effectively and safely used to treat ischemic stroke by promoting neurogenesis, regulating post-infarct inflammatory responses, and restoring mitochondrial function in both the infarct region and hippocampus.

Growth Factors and Their Application in the Therapy of Hereditary Neurodegenerative Diseases

Hereditary neurodegenerative diseases (hNDDs) such as Alzheimer's, Parkinson's, Huntington's disease, and others are primarily characterized by their progressive nature, severely compromising both the cognitive and motor abilities of patients. The underlying genetic component in hNDDs contributes to disease risk, creating a complex genetic landscape. Considering the fact that growth factors play crucial roles in regulating cellular processes, such as proliferation, differentiation, and survival, they could have therapeutic potential for hNDDs, provided appropriate dosing and safe delivery approaches are ensured. This article presents a detailed overview of growth factors, and explores their therapeutic potential in treating hNDDs, emphasizing their roles in neuronal survival, growth, and synaptic plasticity. However, challenges such as proper dosing, delivery methods, and patient variability can hinder their clinical application.

The miR-9-5p/CXCL11 pathway is a key target of hydrogen sulfide-mediated inhibition of neuroinflammation in hypoxic ischemic brain injury

We previously showed that hydrogen sulfide (H2S) has a neuroprotective effect in the context of hypoxic ischemic brain injury in neonatal mice. However, the precise mechanism underlying the role of H2S in this situation remains unclear. In this study, we used a neonatal mouse model of hypoxic ischemic brain injury and a lipopolysaccharide-stimulated BV2 cell model and found that treatment with L-cysteine, a H2S precursor, attenuated the cerebral infarction and cerebral atrophy induced by hypoxia and ischemia and increased the expression of miR-9-5p and cystathionine β synthase (a major H2S synthetase in the brain) in the prefrontal cortex. We also found that an miR-9-5p inhibitor blocked the expression of cystathionine β synthase in the prefrontal cortex in mice with brain injury caused by hypoxia and ischemia. Furthermore, miR-9-5p overexpression increased cystathionine-β-synthase and H2S expression in the injured prefrontal cortex of mice with hypoxic ischemic brain injury. L-cysteine decreased the expression of CXCL11, an miR-9-5p target gene, in the prefrontal cortex of the mouse model and in lipopolysaccharide-stimulated BV-2 cells and increased the levels of proinflammatory cytokines BNIP3, FSTL1, SOCS2 and SOCS5, while treatment with an miR-9-5p inhibitor reversed these changes. These findings suggest that H2S can reduce neuroinflammation in a neonatal mouse model of hypoxic ischemic brain injury through regulating the miR-9-5p/CXCL11 axis and restoring β-synthase expression, thereby playing a role in reducing neuroinflammation in hypoxic ischemic brain injury.

The microRNAs (miRs) overexpressing mesenchymal stem cells (MSCs) therapy in neurological disorders; hope or hype

Altered expression of multiple miRNAs was found to be extensively involved in the pathogenesis of different neurological disorders including Alzheimer's disease, Parkinson's disease, stroke, epilepsy, multiple sclerosis, amyotrophic lateral sclerosis, and Huntington's disease. One of the biggest concerns within gene-based therapy is the delivery of the therapeutic microRNAs to the intended place, which is obligated to surpass the biological barriers without undergoing degradation in the bloodstream or renal excretion. Hence, the delivery of modified and unmodified miRNA molecules using excellent vehicles is required. In this light, mesenchymal stem cells (MSCs) have attracted increasing attention. The MSCs can be genetically modified to express or overexpress a particular microRNA aimed with promote neurogenesis and neuroprotection. The current review has focused on the therapeutic capabilities of microRNAs-overexpressing MSCs to ameliorate functional deficits in neurological conditions.

Focal ischemic stroke modifies microglia-derived exosomal miRNAs: potential role of mir-212-5p in neuronal protection and functional recovery

BACKGROUND

Ischemic stroke is a severe type of stroke with high disability and mortality rates. In recent years, microglial exosome-derived miRNAs have been shown to be promising candidates for the treatment of ischemic brain injury and exert neuroprotective effects. Mechanisms underlying miRNA dysregulation in ischemic stroke are still being explored. Here, we aimed to verify whether miRNAs derived from exosomes exert effects on functional recovery.

METHODS

MiR-212-5p agomir was employed to upregulate miR-212-5p expression in a rat model of middle cerebral artery occlusion/reperfusion (MCAO/R) as well as an oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro. Western blot analysis, qRT-PCR and immunofluorescence staining and other methods were applied to explore the underlying mechanisms of action of miR-212-5p.

RESULTS

The results of our study found that intervention with miR-212-5p agomir effectively decreased infarct volume and restored motor function in MCAO/R rats. Mechanistically, miR-212-5p agomir significantly reduced the expression of PlexinA2 (PLXNA2). Additionally, the results obtained in vitro were similar to those achieved in vivo.

CONCLUSION

In conclusion, the present study indicated that PLXNA2 may be a target gene of miR-212-5p, and miR-212-5p has great potential as a target for the treatment and diagnosis of ischemic stroke.

Neuronal Responses to Ischemia: Scoping Review of Insights from Human-Derived In Vitro Models

Translation of neuroprotective treatment effects from experimental animal models to patients with cerebral ischemia has been challenging. Since pathophysiological processes may vary across species, an experimental model to clarify human-specific neuronal pathomechanisms may help. We conducted a scoping review of the literature on human neuronal in vitro models that have been used to study neuronal responses to ischemia or hypoxia, the parts of the pathophysiological cascade that have been investigated in those models, and evidence on effects of interventions. We included 147 studies on four different human neuronal models. The majority of the studies (132/147) was conducted in SH-SY5Y cells, which is a cancerous cell line derived from a single neuroblastoma patient. Of these, 119/132 used undifferentiated SH-SY5Y cells, that lack many neuronal characteristics. Two studies used healthy human induced pluripotent stem cell derived neuronal networks. Most studies used microscopic measures and established hypoxia induced cell death, oxidative stress, or inflammation. Only one study investigated the effect of hypoxia on neuronal network functionality using micro-electrode arrays. Treatment targets included oxidative stress, inflammation, cell death, and neuronal network stimulation. We discuss (dis)advantages of the various model systems and propose future perspectives for research into human neuronal responses to ischemia or hypoxia.

Potential Regulation of miRNA-29 and miRNA-9 by Estrogens in Neurodegenerative Disorders: An Insightful Perspective

Finding a link between a hormone and microRNAs (miRNAs) is of great importance since it enables the adjustment of genetic composition or cellular functions without needing gene-level interventions. The dicer-mediated cleavage of precursor miRNAs is an interface link between miRNA and its regulators; any disruption in this process can affect neurogenesis. Besides, the hormonal regulation of miRNAs can occur at the molecular and cellular levels, both directly, through binding to the promoter elements of miRNAs, and indirectly, via regulation of the signaling effects of the post-transcriptional processing proteins. Estrogenic hormones have many roles in regulating miRNAs in the brain. This review discusses miRNAs, their detailed biogenesis, activities, and both the general and estrogen-dependent regulations. Additionally, we highlight the relationship between miR-29, miR-9, and estrogens in the nervous system. Such a relationship could be a possible etiological route for developing various neurodegenerative disorders.

Up-Regulation of miR-9-5p Inhibits Hypoxia-Ischemia Brain Damage Through the DDIT4-Mediated Autophagy Pathways in Neonatal Mice

Introduction

Hypoxia-ischemia (HI) remains the leading cause of cerebral palsy and long-term neurological sequelae in infants. Despite intensive research and many therapeutic approaches, there are limited neuroprotective strategies against HI insults. Herein, we reported that HI insult significantly down-regulated microRNA-9-5p (miR-9-5p) level in the ipsilateral cortex of neonatal mice.

Methods

The biological function and expression patterns of protein in the ischemic hemispheres were evaluated by qRT-PCR, Western Blotting analysis, Immunofluorescence and Immunohistochemistry. Open field test and Y-maze test were applied to detect locomotor activity and exploratory behavior and working memory.

Results

Overexpression of miR-9-5p effectively alleviated brain injury and improved neurological behaviors following HI insult, accompanying with suppressed neuroinflammation and apoptosis. MiR-9-5p directly bound to the 3' untranslated region of DNA damage-inducible transcript 4 (DDIT4) and negatively regulated its expression. Furthermore, miR-9-5p mimics treatment down-regulated light chain 3 II/light chain 3 I (LC3 II/LC3 I) ratio and Beclin-1 expression and decreased LC3B accumulation in the ipsilateral cortex. Further analysis showed that DDIT4 knockdown conspicuously inhibited the HI-up-regulated LC3 II/ LC3 I ratio and Beclin-1 expression, associating with attenuated brain damage.

Conclusion

The study indicates that miR-9-5p-mediated HI injury is regulated by DDIT4-mediated autophagy pathway and up-regulation of miR-9-5p level may provide a potential therapeutic effect on HI brain damage.

Potentials of miR-9-5p in promoting epileptic seizure and improving survival of glioma patients

Background

Epilepsy affects over 70 million people worldwide; however, the underlying mechanisms remain unclear. MicroRNAs (miRNAs) have essential functions in epilepsy. miRNA-9, a brain-specific/enriched miRNA, plays a role in various nervous system diseases and tumors, but whether miRNA-9 is involved in epilepsy and glioma-associated epilepsy remains unknown. Therefore, we aimed to explore the potential role of miR-9-5p in seizures and its effect on the survival of glioma patients, in order to provide new targets for the treatment of epilepsy and glioma.

Methods

The YM500v2 database was used to validate the expression of hsa-miR-9-5p in tissues. Moreover, qRT-PCR was performed to investigate the expression of miR-9-5p in temporal lobe epilepsy patients and rats with lithium-pilocarpine-induced seizures. Recombinant adeno-associated virus containing miR-9-5p was constructed to overexpress miR-9-5p in vivo. The effects of miR-9-5p on the behavior and electroencephalographic activities of the lithium-pilocarpine rat model of epilepsy were tested. Bioinformatics analysis was used to predict the targets of miR-9-5p and explore its potential role in epilepsy and glioma-associated epilepsy.

Results

The expression of miR-9-5p increased at 6 h and 7 days after lithium-pilocarpine-induced seizures in rats. Overexpression of miR-9-5p significantly shortened the latency of seizures and increased seizure intensity at 10 min and 20 min after administration of pilocarpine (P < 0.05). Predicted targets of miR-9-5p were abundant and enriched in the brain, and affected various pathways related to epilepsy and tumor. Survival analysis revealed that overexpression of miR-9-5p significantly improved the survival of patients from with low-grade gliomas and glioblastomas. The involvement of miR-9-5p in the glioma-associated epileptic seizures and the improvement of glioma survival may be related to multiple pathways, including the Rho GTPases and hub genes included SH3PXD2B, ARF6, and ANK2.

Conclusions

miR-9-5p may play a key role in promoting epileptic seizures and improving glioma survival, probably through multiple pathways, including GTPases of the Rho family and hub genes including SH3PXD2B, ARF6 and ANK2. Understanding the roles of miR-9-5p in epilepsy and glioma and the underlying mechanisms may provide a theoretical basis for the diagnosis and treatment of patients with epilepsy and glioma.

The role of microRNAs in neurodegenerative diseases: a review

MicroRNAs (miRNAs) are non-coding RNAs which are essential post-transcriptional gene regulators in various neuronal degenerative diseases and playact a key role in these physiological progresses. Neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, multiple sclerosis, and, stroke, are seriously threats to the life and health of all human health and life kind. Recently, various studies have reported that some various miRNAs can regulate the development of neurodegenerative diseases as well as act as biomarkers to predict these neuronal diseases conditions. Endogenic miRNAs such as miR-9, the miR-29 family, miR-15, and the miR-34 family are generally dysregulated in animal and cell models. They are involved in regulating the physiological and biochemical processes in the nervous system by targeting regulating different molecular targets and influencing a variety of pathways. Additionally, exogenous miRNAs derived from homologous plants and defined as botanmin, such as miR2911 and miR168, can be taken up and transferred by other species to be and then act analogously to endogenic miRNAs to regulate the physiological and biochemical processes. This review summarizes the mechanism and principle of miRNAs in the treatment of some neurodegenerative diseases, as well as discusses several types of miRNAs which were the most commonly reported in diseases. These miRNAs could serve as a study provided some potential biomarkers in neurodegenerative diseases might be an ideal and/or therapeutic targets for neurodegenerative diseases. Finally, the role accounted of the prospective exogenous miRNAs involved in mammalian diseases is described.

Mesenchymal stem cell-derived extracellular vesicle-enclosed miR-93 prevents hypoxic-ischemic brain damage in rats

Hypoxic-ischemic brain damage (HIBD) usually induces chronic neurological disorder and even acute death, but effective neuroprotective strategy is still limited. Herein, we performed this study to clarify the mechanism of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) containing microRNA-93 (miR-93) in influencing this damage via regulation of the histone deacetylase 4 (HDAC4)/B-cell lymphoma-2 (Bcl-2) axis. Initially, differentially expressed Bcl-2 was identified in middle cerebral artery occlusion (MCAO), and the upstream regulatory miR-93 and its potential target HDAC4 were also predicted through bioinformatics analysis. HIBD was modeled in vitro by exposing hippocampal neurons to oxygen-glucose deprivation (OGD) and in vivo by MCAO in rats. EVs were isolated from the bone marrow MSCs of well-grown rats. Our experimental data validated that HDAC4 was highly expressed while miR-93 and Bcl-2 were poorly expressed in MCAO rats. Furthermore, HDAC4 overexpression, through inhibiting Bcl-2 via deacetylation, promoted the infarct volume and pathological changes in hippocampal tissues and neuron apoptosis, and impaired neurobehavioral ability of MCAO rats. Of note, miR-93 was found to target HDAC4. Importantly, MSC-derived EVs overexpressing miR-93 suppressed HDAC4 expression and subsequently impeded the apoptosis of OGD-exposed hippocampal neurons in vitro, and also ameliorated HIBD in vivo. Taken together, miR-93 delivered by MSC-derived EVs can ameliorate HIBD by suppressing hippocampal neuron apoptosis through targeting the HDAC4/Bcl-2 axis, a finding which may be of great significance in the treatment of HIBD.

An integrated chemo-informatics and in vitro experimental approach repurposes acarbose as a post-ischemic neuro-protectant

The increasing prevalence of ischemic stroke combined with limited therapeutic options highlights the compelling need for continued research into the development of future neuro-therapeutics. Death-Associated Protein Kinase 1 (DAPK1) and p53 protein-protein interaction serve as a signaling point for the convergence of apoptosis and necrosis in cerebral ischemia. In this study, we used an integrated chemo-informatics and in vitro experimental drug repurposing strategy to screen potential small-molecule inhibitors of DAPK1-p53 interaction from the United States of America Food and Drug Administration (FDA) approved drug database exhibiting post-ischemic neuroprotective and neuro-regenerative efficacy and mechanisms. The computational docking and molecular dynamics simulation of FDA-approved drugs followed by an in vitro experimental validation identified acarbose, an anti-diabetic medication and caloric restriction mimetic as a potential inhibitor of DAPK1-p53 interaction. The evaluation of post-ischemic neuroprotective and regenerative efficacy and mechanisms of action for acarbose was carried out using a set of experimental methods, including cell viability, proliferation and differentiation assays, fluorescence staining, and gene expression analysis. Post-ischemic administration of acarbose conferred significant neuroprotection against ischemia-reperfusion injury in vitro. The reduced fluorescence emission in cells stained with _pS²⁰ supported the potential of acarbose in inhibiting the DAPK1-p53 interaction. Acarbose prevented mitochondrial and lysosomal dysfunction, and favorably modulated gene expression related to cell survival, inflammation, and regeneration. BrdU staining and neurite outgrowth assay showed a significant increase in cell proliferation and differentiation in acarbose-treated group. This is the first study known to provide mechanistic insight into the post-ischemic neuroprotective and neuro-regenerative potential of acarbose. Our results provide a strong basis for preclinical studies to evaluate the safety and neuroprotective efficacy of acarbose against ischemic stroke.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-022-03130-5.

Neuroprotective and Proneurogenic Effects of Glucosamine in an Internal Carotid Artery Occlusion Model of Ischemia

Neuroprotective, antineuroinflammatory, and proneurogenic effects of glucosamine, a naturally occurring amino sugar, have been reported in various animal models of brain injury including cerebral ischemia and hypoxic brain damage. Given that clinical translation of therapeutic candidates identified in animal models of ischemic stroke has remained unsatisfactory in general, possibly due to inadequacy of existing models, we sought to study the effects of glucosamine in a recently developed, clinical condition mimicking mouse model of internal cerebral artery occlusion. In this model of mild to moderate striatal damage, glucosamine ameliorated behavioral dysfunction, rescued ischemia-induced striatal damage, and suppressed ischemia-induced upregulation of proinflammatory genes in striatal tissue. Further, in ex vivo neurosphere assay involving neural stem cells/neural progenitor cells from subventricular zone, glucosamine increased the number of large neurospheres, along with enhancing mRNA levels of the proliferation markers Nestin, NeuroD1, and Sox2. Lastly, coronal brain sections containing the striatal region with subventricular zone showed increased number of BrdU positive cells and DCX positive cells, a marker for newly differentiating and immature neurons, in glucosamine-treated ischemic mice. Cumulatively, the results confirming neuroprotective, antineuroinflammatory, and proneurogenic effects of glucosamine enhance drug repurposing potential of glucosamine in cerebral ischemia.

Histone deacetylase in neuropathology

Neuroepigenetics, a new branch of epigenetics, plays an important role in the regulation of gene expression. Neuroepigenetics is associated with holistic neuronal function and helps in formation and maintenance of memory and learning processes. This includes neurodevelopment and neurodegenerative defects in which histone modification enzymes appear to play a crucial role. These modifications, carried out by acetyltransferases and deacetylases, regulate biologic and cellular processes such as apoptosis and autophagy, inflammatory response, mitochondrial dysfunction, cell-cycle progression and oxidative stress. Alterations in acetylation status of histone as well as non-histone substrates lead to transcriptional deregulation. Histone deacetylase decreases acetylation status and causes transcriptional repression of regulatory genes involved in neural plasticity, synaptogenesis, synaptic and neural plasticity, cognition and memory, and neural differentiation. Transcriptional deactivation in the brain results in development of neurodevelopmental and neurodegenerative disorders. Mounting evidence implicates histone deacetylase inhibitors as potential therapeutic targets to combat neurologic disorders. Recent studies have targeted naturally-occurring biomolecules and micro-RNAs to improve cognitive defects and memory. Multi-target drug ligands targeting HDAC have been developed and used in cell-culture and animal-models of neurologic disorders to ameliorate synaptic and cognitive dysfunction. Herein, we focus on the implications of histone deacetylase enzymes in neuropathology, their regulation of brain function and plausible involvement in the pathogenesis of neurologic defects.

Knockdown of lncRNA SNHG15 Ameliorates Oxygen and Glucose Deprivation (OGD)-Induced Neuronal Injury via Regulating the miR-9-5p/TIPARP Axis

Stroke is a cerebrovascular disease with impaired nerve function. Long non-coding RNA (lncRNA) is considered to be an important regulator of various diseases. Nevertheless, the role of lncRNA small nucleolar RNA host gene 15 (SNHG15) in cerebral ischemia injury induced by stroke is still unclear. Cell-counting kit 8 assay and flow cytometry were used to detect cell viability and apoptosis, respectively. The caspase3 activity of cells was measured using Caspase3 Activity Assay Kit. Besides, the protein levels of apoptosis markers and TCCD-induced poly (ADP)-ribose polymerase (TIPARP) were determined using western blot analysis. Moreover, quantitative real-time polymerase chain reaction was employed to examine the relative expression of SNHG15 and miR-9-5p. Furthermore, dual-luciferase reporter assay was used to assess the interaction between miR-9-5p and SNHG15 or TIPARP. In addition, biotin-labeled RNA pull-down assay was performed to evaluate the interaction between miR-9-5p and SNHG15 further. Middle cerebral artery occlusion (MCAO) model was constructed to further explore the role of SNHG15 in neuronal injury in vivo. Our data showed that oxygen and glucose deprivation (OGD) could induce N-2a cell injury and enhance SNHG15 expression. Silenced SNHG15 could promote the viability and suppress the apoptosis of OGD-induced N-2a cells. Also, SNHG15 knockdown also could alleviate the neuronal injury of MCAO mice. Mechanistically, SNHG15 could sponge miR-9-5p, and miR-9-5p could target TIPARP. Further experiments revealed that miR-9-5p inhibition or TIPARP overexpression could reverse the suppressive effect of SNHG15 knockdown on OGD-induced N-2a cell injury. Our findings indicated that SNHG15 knockdown inhibited neuronal injury through the miR-9-5p/TIPARP axis, suggesting that SNHG15 might be a potential target for cerebral ischemia injury induced by stroke.

RETRACTED: Inhibition of interleukin-1β plays a protective role in Alzheimer's disease by promoting microRNA-9-5p and downregulating targeting protein for xenopus kinesin-like protein 2

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figs. 2C, 4C, and 5B+E, which appear to have the same eyebrow shaped phenotype as many other publications tabulated here (https://docs.google.com/spreadsheets/d/149EjFXVxpwkBXYJOnOHb6RhAqT4a2llhj9LM60MBffM/edit#gid=0 [docs.google.com]). The journal requested the corresponding author comment on these concerns and provide the raw data. However the authors were not able to satisfactorily fulfil this request and therefore the Editor-in-Chief decided to retract the article.

The neuroprotective effect of MicroRNA-149-5p and coenzymeQ10 by reducing levels of inflammatory cytokines and metalloproteinases following focal brain ischemia in rats

The increase in some factors following cerebral ischemia, especially Matrix metalloproteinase (MMPs) and inflammatory factors lead to blood-brain barrier (BBB) damages, edema and neuronal death. Previous studies have shown that these molecules are miRNA-149-5p (miR-149) and Coenzyme (Co) Q10 targets. Therefore, in this study, the effect of mimic of miRNA-149-5p (mimic miR) and CoQ10 on the expression of metalloproteinase 1 and 2 and inflammatory cytokines following injury caused by cerebral ischemia is investigated. Cerebral ischemia was modeled by Middle Cerebral Artery Occlusion (MCAO). Male Wistar rats were randomly divided into 6 groups: sham (without surgery and treatment), control (MCAO), negative control (NC): MCAO + scrambled miR, vehicle: MCAO + Ethanole, first treatment: MCAO + mimic miR, second treatment: MCAO + Q10. Each group was divided into 6 subgroups to evaluate neurological defects, the volume of tissue damage using 2,3,5-triphenyl tetrazolium chloride (TTC) staining, blood-brain barrier permeability using cerebral Evans Blue (EB) staining, edema by measuring the percentage of brain water, MMP-2,9 mRNA and miR-149-5p levels using Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) and the levels of IL-6 and TNF-α proteins using ELISA. The data obtained from this study showed that the use of mimic miR and Q10 increased the level of miR-149, decreased the extent of neurological defects and tissue damage, increased BBB integrity, decreased brain water percentage and also decreased the level of inflammatory cytokines and MMPs. It seems that the use mimic of miRNA-149-5p and Q10 can have a protective effect on the brain by reducing MMPs and inflammatory factors following cerebral ischemia and this could lead to a new treatment strategy to reduce the complications of cerebral ischemia.

Potential role of exosome in post-stroke reorganization and/or neurodegeneration

Currently, stroke is a common and devastating condition, which is sometimes associated with permanent cerebral damages. Although in early time after stroke, the related treatments are mainly focused on the restoration of cerebral blood flow (CBF), at the same time, some changes are commencing that continue for a long time and need to be specially noticed. Previous studies have proposed several molecular mechanisms in these post-stroke events. Exosomes are a type of vesicle, which are formed and secreted by most cells as a mean to transfer cellular constituents such as proteins, DNA and/or RNA to distant cells. Therefore, they are considered as a novel mechanism of cellular communication. Herein, we reviewed the current knowledge on cascades, which are activated after stroke and consequently lead to the reorganization and/or continuance of tissue damage and development of other disorders such as Neurodegenerative diseases (ND). Thereafter, we summarized the latest proofs about the possible participation of exosomes in transferring some components such as proteins and micro-RNAs (miRs), from the affected areas to other parts of the brain and eventually cause the above-mentioned post-stroke events.

Matrine protects PC12 cells from lipopolysaccharide-evoked inflammatory injury via upregulation of miR-9

Context: Matrine is a well-known anti-inflammatory quinolizidine alkaloid derived from leguminous plant Sophora flavescens Ait. (Leguminosae).Objective: This study was designed to uncover the potential application of matrine in treating spinal cord injury (SCI).Materials and methods: Neuron-like PC12 cells in experimental groups were pre-treated with/without matrine (200 μM) for 24 h and then stimulated by lipopolysaccharide (LPS, 5 μg/mL) for 12 h. PC12 cells in control group were cultured in complete medium. CCK-8 assay, flow cytometry, qRT-PCR, western blot and ELISA were performed to evaluate cell damage. Moreover, after cells were transfected with miR-9 inhibitor for 48 h, above indicators were tested again. qRT-PCR and western blot were also conducted to uncover the downstream effectors and signalling pathways for matrine.Results: LPS (5 μg/mL) decreased cell viability about 50%. Matrine (200 μM) decreased cell viability about 0%, 13.8% and 30% at 24 h, 48 h and 72 h, respectively. The loss of viability, stimulation of apoptosis, and release of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) evoked by LPS were attenuated by the pre-treatment of matrine partly. Meanwhile, LPS reduced miR-9 expression about 60%, but matrine completely reversed LPS-decreased miR-9 level. By silencing miR-9 expression, the protective properties of matrine towards PC12 cells were impeded. Besides, matrine inhibited the activation of JNK and NF-κB pathways even under the condition of LPS. And the impact of matrine on the signalling were attenuated by miR-9 silencing.Discussion and Conclusion: This paper provided in vitro evidence that matrine was able to protect PC12 cells against LPS-evoked damage. The neuroprotective properties of matrine may be due to its regulation of miR-9 expression as well as JNK and NF-κB pathways.

Epigenetic Mechanisms Underlying Adult Post Stroke Neurogenesis

Stroke remains the leading cause of adult disability. Post-stroke neurogenesis contributes to functional recovery. As an intrinsic neurorestorative process, it is important to elucidate the molecular mechanism underlying stroke-induced neurogenesis and to develop therapies designed specifically to augment neurogenesis. Epigenetic mechanisms include DNA methylation, histone modification and its mediation by microRNAs and long-non-coding RNAs. In this review, we highlight how epigenetic factors including DNA methylation, histone modification, microRNAs and long-non-coding RNAs mediate stroke-induced neurogenesis including neural stem cell self-renewal and cell fate determination. We also summarize therapies targeting these mechanisms in the treatment of stroke.

Upregulation of miRNA-9-5p Promotes Angiogenesis after Traumatic Brain Injury by Inhibiting Ptch-1

MicroRNA-9-5p (miRNA-9-5p) is an important regulator of angiogenesis in many pathological states. However, the effect of miRNA-9-5p on angiogenesis after traumatic brain injury (TBI) has not been elucidated. In this study, a controlled cortical impact (CCI) model was used to induce TBI in Sprague-Dawley rats, and an oxygen glucose deprivation (OGD) model was used to mimic the pathological state in vitro. Brain microvascular endothelial cells (BMECs) were extracted from immature rats. The results showed that the level of miRNA-9-5p was significantly increased in the traumatic foci after TBI, and the upregulation of miRNA9-5p promoted the recovery of neurological function. Moreover, the upregulation of miRNA-9-5p with miRNA agomir significantly increased the density of the microvascular and neurons around the traumatic foci in rats after TBI. The results of the in vitro experiments confirmed that the upregulation of miRNA-9-5p with a miRNA mimic improved cellular viability and alleviated cellular apoptosis. Dual luciferase reporter assay validated that miRNA-9-5p was a posttranscriptional modulator of Ptch-1. Activation of the Hedgehog pathway by increasing the level of miRNA-9-5p promoted the migration and tube formation of BMECs in vitro. In addition, we found that the upregulation of miRNA-9-5p activated the Hedgehog pathway and increased the phosphorylation of AKT, which promoted the expression of cyclin D1, MMP-9 and VEGF in BMECs. All these results indicate that the upregulation of miRNA-9-5p promotes angiogenesis and improves neurological functional recovery after TBI, mainly by activating the Hedgehog pathway. MiRNA-9-5p may be a potential new therapeutic target for TBI.

Neuroprotective effects of miR-532-5p against ischemic stroke

Stroke can cause death and disability and has a high incidence with many complications. So far, effective treatment options for stroke are still limited. MicroRNA-532-5p (miR-532-5p) is significantly downregulated in stroke. However, the role of miR-532-5p in ischemic stroke is still unclear. In this study, we established an in vivo middle cerebral artery occlusion (MCAO) model in mice. The expression level of miR-532-5p, neurological score, infarct area, neuronal apoptosis, and phosphoinositide 3-kinase (PI3K)/Akt signaling pathway-related molecules were examined. Low miR-532-5p levels and high phosphatase and tensin homolog deleted on chromosome 10 (PTEN) levels were detected in the mouse MCAO model. MiR-532-5p overexpression improved neurological dysfunction, reduced the infarct area, attenuated neuronal injury and apoptosis, and promoted the activation of the PI3K/Akt signaling pathway in MCAO mice. In vitro, we treated mouse neuroblastoma cells (N2a) with oxygen-glucose deprivation and reperfusion (OGD/R). The expression level of miR-532-5p, cell viability, cell apoptosis, and the PI3K/Akt signaling pathway-related molecules were detected. Consistent with the in vivo tests, the miR-532-5p level was decreased and the PTEN level was increased in OGD-treated N2a cells in vitro. The miR-532-5p mimic increased cell viability, decreased cell apoptosis, and activated the PI3K/Akt signaling pathway. Furthermore, PTEN was verified as a target gene of miR-532-5p by luciferase reporter assay. PTEN overexpression attenuated the protective effect of miR-532-5p in OGD-treated N2a cells. In summary, these findings reveal that miR-532-5p protects against ischemic stroke by inhibiting PTEN and activating the PI3K/Akt signaling pathway and may serve as a novel therapeutic target for ischemic stroke.

The role of histone deacetylase 4 during chondrocyte hypertrophy and endochondral bone development

Chondrocyte hypertrophy represents a crucial turning point during endochondral bone development. This process is tightly regulated by various factors, constituting a regulatory network that maintains normal bone development. Histone deacetylase 4 (HDAC4) is the most well-characterized member of the HDAC class IIa family and participates in different signalling networks during development in various tissues by promoting chromatin condensation and transcriptional repression. Studies have reported that HDAC4-null mice display premature ossification of developing bones due to ectopic and early-onset chondrocyte hypertrophy. Overexpression of HDAC4 in proliferating chondrocytes inhibits hypertrophy and ossification of developing bones, which suggests that HDAC4, as a negative regulator, is involved in the network regulating chondrocyte hypertrophy. Overall, HDAC4 plays a key role during bone development and disease. Thus, understanding the role of HDAC4 during chondrocyte hypertrophy and endochondral bone formation and its features regarding the structure, function, and regulation of this process will not only provide new insight into the mechanisms by which HDAC4 is involved in chondrocyte hypertrophy and endochondral bone development, but will also create a platform for developing a therapeutic strategy for related diseases.

Cite this article:Bone Joint Res. 2020;9(2):82–89.

microRNA-9-5p alleviates blood-brain barrier damage and neuroinflammation after traumatic brain injury

The level of microRNA‐9‐5p (miRNA‐9‐5p) in brain tissues is significantly changed after traumatic brain injury (TBI). However, the effect of miRNA‐9‐5p for brain function in TBI has not been elucidated. In this study, a controlled cortical impact model was used to induce TBI in Sprague–Dawley rats, and an oxygen glucose deprivation model was used to mimic the pathological state in vitro. Brain microvascular endothelial cells (BMECs) and astrocytes were extracted from immature Sprague–Dawley rats and cocultured to reconstruct blood–brain barrier (BBB) in vitro. The results show that the level of miRNA‐9‐5p was significantly increased in brain tissues after TBI, and up‐regulation of miRNA9‐5p contributed to the recovery of neurological function. Up‐regulation of miRNA‐9‐5p with miRNA agomir may significantly alleviate apoptosis, neuroinflammation, and BBB damage in rats after TBI. Moreover, a dual luciferase reporter assay confirmed that miRNA‐9‐5p is a post‐transcriptional modulator of Ptch‐1. In in vitro experiments, the results confirmed that up‐regulation of miRNA‐9‐5p with miRNA mimic alleviates cellular apoptosis, inflammatory response, and BBB damage mainly by inhibiting Ptch‐1. In addition, we found that the activation of Hedgehog pathway was accompanied by inhibition of NF‐κB/MMP‐9 pathway in the BMECs treated with miRNA‐9‐5p mimic. Taken together, these results indicate that up‐regulation of miRNA‐9‐5p alleviates BBB damage and neuroinflammatory responses by activating the Hedgehog pathway and inhibiting NF‐κB/MMP‐9 pathway, which promotes the recovery of neurological function after TBI.

Pharmacological intervention of histone deacetylase enzymes in the neurodegenerative disorders

Reversal of aging symptoms and related disorders are the challenging task where epigenetic is a crucial player that includes DNA methylation, histone modification; chromatin remodeling and regulation that are linked to the progression of various neurodegenerative disorders (NDDs). Overexpression of various histone deacetylase (HDACs) can activate Glycogen synthase kinase 3 which promotes the hyperphosphorylation of tau and inhibits its degradation. While HDAC is important for maintaining the neuronal morphology and brain homeostasis, at the same time, these enzymes are promoting neurodegeneration, if it is deregulated. Different experimental models have also confirmed the neuroprotective effects caused by HDAC enzymes through the regulation of neuronal apoptosis, inflammatory response, DNA damage, cell cycle regulation, and metabolic dysfunction. Apart from transcriptional regulation, protein-protein interaction, histone post-translational modifications, deacetylation mechanism of non-histone protein and direct association with disease proteins have been linked to neuronal imbalance. Histone deacetylases inhibitors (HDACi) can be able to alter gene expression and shown its efficacy on experimental models, and in clinical trials for NDD's and found to be a very promising therapeutic agent with certain limitation, for instance, non-specific target effect, isoform-selectivity, specificity, and limited number of predicted biomarkers. Herein, we discussed (i) the catalytic mechanism of the deacetylation process of various HDAC's in in vivo and in vitro experimental models, (ii) how HDACs are participating in neuroprotection as well as in neurodegeneration, (iii) a comprehensive role of HDACi in maintaining neuronal homeostasis and (iv) therapeutic role of biomolecules to modulate HDACs.

Long Non-Coding RNA SNHG7 Alleviates Oxygen and Glucose Deprivation/Reoxygenation-Induced Neuronal Injury by Modulating miR-9/SIRT1 Axis in PC12 Cells: Potential Role in Ischemic Stroke

OBJECTIVE

The roles of long non-coding RNA (lncRNAs) in ischemic stroke (IS) have been widely illustrated. Here, we focused on the function and mechanism of lncRNA SNHG7 in IS.

METHODS

Middle cerebral artery occlusion (MCAO) was used for inducing mice to establish IS models in vivo. Oxygen and glucose deprivation/reoxygenation (OGD/R) was used for treating PC12 cells to establish IS models in vitro. Relative expression of SNHG7 and miR-9 was determined by qRT-PCR. The neuronal injury was assessed by measuring relative activity of ROS, malondialdehyde (MDA) level and cell viability. Cell viability was determined by MTT assay. Dual-luciferase reporter (DLR) assay was employed to test the target of SNHG7 or miR-9. Western blot was used to determine the protein expression of SIRT1. Apoptosis rate was measured by flow cytometry.

RESULTS

SNHG7 was down-regulated and miR-9 was up-regulated by MCAO treatment in brain tissues of mice and by OGD/R treatment in PC12 cells. Overexpression of SNHG7 or suppression of miR-9 decreased the relative activity of ROS and the MDA level as well as enhancing cell viability, and SNHG7 reduced apoptosis rate in OGD/R-induced PC12 cells (IS cells). MiR-9 was targeted by SNHG7 and SIRT1 was targeted by miR-9. The protein expression of SIRT1 was reduced by OGD/R treatment in PC12 cells. The suppressive effects of SNHG7 on the relative activity of ROS, the MDA level and apoptosis rate as well as the promotion effect of SNHG7 on cell viability were reversed by miR-9 mimics or sh-SIRT1 in IS cells.

CONCLUSION

LncRNA SNHG7 alleviated OGD/R-induced neuronal injury by mediating miR-9/SIRT1 axis in vitro.

Exosomal miRNAs in central nervous system diseases: biomarkers, pathological mediators, protective factors and therapeutic agents

Exosomes are small bilipid layer-enclosed extracellular vesicles that can be found in tissues and biological fluids. As a key cell-to-cell and distant communication mediator, exosomes are involved in various central nervous system (CNS) diseases, potentially through transferring their contents such as proteins, lipids and nucleic acids to the target cells. Exosomal miRNAs, which are small non-coding RNAs in the exosomes, are known to be more stable than free miRNAs and therefore have lasting effects on disease-related gene expressions. There are distinct profiles of exosomal miRNAs in different types of CNS diseases even before the onset of irreversible neurological damages, indicating that exosomal miRNAs within tissues and biological fluids could serve as promising biomarkers. Emerging evidence has also demonstrated the pathological effects of several exosomal miRNAs in CNS diseases via specific modulation of disease-related factors. Moreover, exosomes carry therapeutically beneficial miRNAs across the blood-brain-barrier, which can be exploited as a powerful drug delivery tool to help alleviating multiple CNS diseases. In this review, we summarize the recent progress made in understanding the biological roles of exosomal miRNAs as potential diagnostic biomarkers, pathological regulators, and therapeutic targets/drugs for CNS diseases. A comprehensive discussion of the main concerns and challenges for the applications of exosomal miRNAs in the clinical setting is also provided.

Prediction of miRNA interaction with mRNA of stroke candidate genes

BACKGROUND

The role of miRNA in tissue affected by stroke is actively studied, but it remains unclear which miRNAs and target genes are involved in the development of stroke.

METHODS

The MirTarget program defines the following features of a miRNA binding to a mRNA: the binding start site, the location of the binding site in mRNA, the free energy of a miRNA binding with a mRNA, and the interaction schemes of miRNA and mRNA.

RESULTS

The interaction of 6565 miRNAs with mRNAs of stroke candidate genes was determined. The association of the mRNAs of stroke candidate genes with miRNAs depends on the level of gene expression. Some highly expressed candidate genes are targets of miR-619-5p and miR-5095, which have binding sites located on overlapping mRNA nucleotide sequences (clusters). miR-619-5p and miR-5095 bind to mRNA of 15 genes. Clusters for the binding of miR-1273f,d,e are in mRNAs of highly expressed genes. The start sites of miR-1273d and miR-1273e binding in all clusters are in sequences with one and ten nucleotides, respectively. The clusters of multiple miR-574-5p and ID00470.5p-miR binding sites and the clusters of the miR-466, ID01030.3p-miR, and ID00436.3p-miR binding sites are in mRNAs of some genes expressed at low levels.

CONCLUSION

The organization of miRNA binding sites into clusters reduces the length of mRNA and creates competition between miRNAs for binding to mRNA of a target gene. The characteristics of miRNA associations with target genes can be used to recommend markers for a diagnosis of stroke.

Ceramide and Sphingosine Regulation of Myelinogenesis: Targeting Serine Palmitoyltransferase Using microRNA in Multiple Sclerosis

Ceramide and sphingosine display a unique profile during brain development, indicating their critical role in myelinogenesis. Employing advanced technology such as gas chromatography-mass spectrometry, high performance liquid chromatography, and immunocytochemistry, along with cell culture and molecular biology, we have found an accumulation of sphingosine in brain tissues of patients with multiple sclerosis (MS) and in the spinal cord of rats induced with experimental autoimmune encephalomyelitis. The elevated sphingosine leads to oligodendrocyte death and fosters demyelination. Ceramide elevation by serine palmitoyltransferse (SPT) activation was the primary source of the sphingosine elevation as myriocin, an inhibitor of SPT, prevented sphingosine elevation and protected oligodendrocytes. Supporting this view, fingolimod, a drug used for MS therapy, reduced ceramide generation, thus offering partial protection to oligodendrocytes. Sphingolipid synthesis and degradation in normal development is regulated by a series of microRNAs (miRNAs), and hence, accumulation of sphingosine in MS may be prevented by employing miRNA technology. This review will discuss the current knowledge of ceramide and sphingosine metabolism (synthesis and breakdown), and how their biosynthesis can be regulated by miRNA, which can be used as a therapeutic approach for MS.

M2 microglia-derived exosomes protect the mouse brain from ischemia-reperfusion injury via exosomal miR-124

Rationale: Microglia play a critical role in modulating cell death and neurobehavioral recovery in response to brain injury either by direct cell-cell interaction or indirect secretion of trophic factors. Exosomes secreted from cells are well documented to deliver bioactive molecules to recipient cells to modulate cell function. Here, we aimed to identify whether M2 microglia exert neuroprotection after ischemic attack through an exosome-mediated cell-cell interaction.

Methods: M2 microglia-derived exosomes were intravenously injected into the mouse brain immediately after middle cerebral artery occlusion. Infarct volume, neurological score, and neuronal apoptosis were examined 3 days after ischemic attack. Exosome RNA and target protein expression levels in neurons and brain tissue were determined for the mechanistic study.

Results: Our results showed that the M2 microglia-derived exosomes were taken up by neurons in vitro and in vivo. M2 microglia-derived exosome treatment attenuated neuronal apoptosis after oxygen-glucose deprivation (p<0.05). In vivo results showed that M2 microglia-derived exosome treatment significantly reduced infarct volume and attenuated behavioral deficits 3 days after transient brain ischemia (p<0.05), whereas injection of miR-124 knockdown (miR-124k/d) M2 microglia-derived exosomes partly reversed the neuroprotective effect. Our mechanistic study further demonstrated that ubiquitin-specific protease 14 (USP14) was the direct downstream target of miR-124. Injection of miR-124k/d M2 exosomes plus the USP14 inhibitor, IU1, achieved comparable neuroprotective effect as injection of M2 exosomes alone.

Conclusions: We demonstrated that M2 microglia-derived exosomes attenuated ischemic brain injury and promoted neuronal survival via exosomal miR-124 and its downstream target USP14. M2 microglia-derived exosomes represent a promising avenue for treating ischemic stroke.