miR-124 upregulates astrocytic glutamate transporter-1 via the Akt and mTOR signaling pathway post ischemic stroke

DL-3-n-butylphthalide inhibits astrocyte activation in the cortical penumbra of ischemia-reperfusion model rats via AKT signaling

Ischemic stroke triggers rapid activation of astrocytes, which contributes to tissue damage. Dl-3-n-butylphthalide (NBP), an independently developed compound in China for the treatment of ischemic stroke, has unclear molecular mechanisms. In this study, we established a Sprague-Dawley rat model of middle cerebral artery occlusion (MCAO) by occluding the middle cerebral artery for 1.5 h followed by reperfusion for 72 h. We assessed neurological scores, infarct volume, neuronal injury, and the expression levels of GFAP, C3, S100A10, GLT-1, p-AKT/AKT, and p-mTOR/mTOR, as well as immunofluorescence double staining of C3/S100A10 with GFAP and GLT-1 respectively. NBP significantly improved neurological function in MCAO rats, reduced infarct area, alleviated neuronal injury, inhibited A1 astrocyte polarization, promoted A2 astrocyte polarization, and upregulated GLT-1 expression. However, the AKT inhibitor (TCN) weakened NBP's regulatory effects on astrocytes and GLT-1. Finally, immunofluorescence experiments showed that GLT-1 colocalized more effectively with A2 astrocytes than with A1 astrocytes. We demonstrated that NBP reduces astrocyte activation and upregulates GLT-1 expression via the AKT/mTOR pathway, providing new insights into therapeutic strategies for ischemic stroke and valuable clues for drug design.

Identification of Disulfidptosis-Related Genes in Ischemic Stroke by Combining Single-Cell Sequencing, Machine Learning Algorithms, and In Vitro Experiments

BACKGROUND

Ischemic stroke (IS) is a severe neurological disorder with a pathogenesis that remains incompletely understood. Recently, a novel form of cell death known as disulfidptosis has garnered significant attention in the field of ischemic stroke research. This study aims to investigate the mechanistic roles of disulfidptosis-related genes (DRGs) in the context of IS and to examine their correlation with immunopathological features.

METHODS

To enhance our understanding of the mechanistic underpinnings of disulfidptosis in IS, we initially retrieved the expression profile of peripheral blood from human IS patients from the GEO database. We then utilized a suite of machine learning algorithms, including LASSO, random forest, and SVM-RFE, to identify and validate pivotal genes. Furthermore, we developed a predictive nomogram model, integrating multifactorial logistic regression analysis and calibration curves, to evaluate the risk of IS. For the analysis of single-cell sequencing data, we employed a range of analytical tools, such as "Monocle" and "CellChat," to assess the status of immune cell infiltration and to characterize intercellular communication networks. Additionally, we utilized an oxygen-glucose deprivation (OGD) model to investigate the effects of SLC7A11 overexpression on microglial polarization.

RESULTS

This study successfully identified key genes associated with disulfidptosis and developed a reliable nomogram model using machine learning algorithms to predict the risk of ischemic stroke. Examination of single-cell sequencing data showed a robust correlation between disulfidptosis levels and the infiltration of immune cells. Furthermore, "CellChat" analysis elucidated the intricate characteristics of intercellular communication networks. Notably, the TNF signaling pathway was found to be intimately linked with the disulfidptosis signature in ischemic stroke. In an intriguing finding, the OGD model demonstrated that SLC7A11 expression suppresses M1 polarization while promoting M2 polarization in microglia.

CONCLUSION

The significance of our findings lies in their potential to shed light on the pathogenesis of ischemic stroke, particularly by underscoring the pivotal role of disulfidptosis-related genes (DRGs). These insights could pave the way for novel therapeutic strategies targeting DRGs to mitigate the impact of ischemic stroke.

The Roles of Non-coding RNA Targeting Astrocytes in Cerebral Ischemia

Astrocytes are key targets for treating cerebral ischemia in the central nervous system. Non-coding RNAs (ncRNAs) participate in the pathological processes of astrocytes in cerebral ischemia. Recent reports suggest that ncRNAs ameliorate the outcome of cerebral ischemia by mediating astrocytes' inflammatory reaction, oxidative stress, excitotoxicity, autophagy, and apoptosis. Reconstructing cellular systems might offer a promising strategy for treating cerebral ischemia. This review briefly discusses the potential of ncRNAs as drug targets and explores the molecular regulatory mechanisms through which ncRNAs target astrocytes in cerebral ischemia. It provides an overview of the current research, discusses ncRNAs' implications as clinical markers for cerebral ischemia, and anticipates that ongoing research on ncRNAs may contribute to novel therapeutic approaches for treating this condition.

mTOR pathway - a potential therapeutic target in stroke

Stroke is ranked as the second leading cause of death worldwide and a major cause of long-term disability. A potential therapeutic target that could offer favorable outcomes in stroke is the mammalian target of rapamycin (mTOR) pathway. mTOR is a serine/threonine kinase that composes two protein complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), and is regulated by other proteins such as the tuberous sclerosis complex. Through a significant number of signaling pathways, the mTOR pathway can modulate the processes of post-ischemic inflammation and autophagy, both of which play an integral part in the pathophysiological cascade of stroke. Promoting or inhibiting such processes under ischemic conditions can lead to apoptosis or instead sustained viability of neurons. The purpose of this review is to examine the pathophysiological role of mTOR in acute ischemic stroke, while highlighting promising neuroprotective agents such as hamartin for therapeutic modulation of this pathway. The therapeutic potential of mTOR is also discussed, with emphasis on implicated molecules and pathway steps that warrant further elucidation in order for their neuroprotective properties to be efficiently tested in future clinical trials.

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

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

miR-124: A Promising Therapeutic Target for Central Nervous System Injuries and Diseases

Central nervous system injuries and diseases, such as ischemic stroke, spinal cord injury, neurodegenerative diseases, glioblastoma, multiple sclerosis, and the resulting neuroinflammation often lead to death or long-term disability. MicroRNAs are small, non-coding, single-stranded RNAs that regulate posttranscriptional gene expression in both physiological and pathological cellular processes, including central nervous system injuries and disorders. Studies on miR-124, one of the most abundant microRNAs in the central nervous system, have shown that its dysregulation is related to the occurrence and development of pathology within the central nervous system. Herein, we review the molecular regulatory functions, underlying mechanisms, and effective delivery methods of miR-124 in the central nervous system, where it is involved in pathological conditions. The review also provides novel insights into the therapeutic target potential of miR-124 in the treatment of human central nervous system injuries or diseases.

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.

Some miRNA expressions and their targets in ischemic stroke

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

LncRNA BIRF Promotes Brain Ischemic Tolerance Induced By Cerebral Ischemic Preconditioning Through Upregulating GLT-1 via Sponging miR-330-5p

Long noncoding RNAs (lncRNAs) play an important regulatory role in various diseases. However, the role of lncRNAs in brain ischemic tolerance (BIT) induced by cerebral ischemic preconditioning (CIPC) is still unknown. The lncRNA profile of rat cortical astrocytes pretreated with ischemic preconditioning was analyzed by high-throughput sequencing. The results of Cell-Counting Kit-8 (CCK-8) assay showed that a novel lncRNA, NONRATT009133.2, which we referred to as brain ischemia-related factor (BIRF), was highly correlated with BIT. Through bioinformatics analysis, we predicted that BIRF, miR-330-5p, and GLT-1 (also named Slc1a2) might constitute a ceRNA regulatory network in the induction of BIT. We found that BIRF was upregulated by CIPC, which promoted GLT-1 expression and BIT induction. BIRF could directly bind to miR-330-5p. Furthermore, miR-330-5p directly targeted GLT-1, and miR-330-5p inhibited both GLT-1 expression and BIT induction in vitro and in vivo. Moreover, BIRF acts as a molecular sponge to competitively bind to miR-330-5p with GLT-1 mRNA, while the miR-330-5p inhibitor reversed all the effects of BIRF siRNA on GLT-1 expression and neuronal vitality. Taken together, our results demonstrate the important roles of the BIRF/miR-330-5p/GLT-1 axis in the induction of BIT by CIPC. BIRF may be a potentially effective therapeutic strategy against stroke injury.

Brain delivering RNA-based therapeutic strategies by targeting mTOR pathway for axon regeneration after central nervous system injury

Injuries to the central nervous system (CNS) such as stroke, brain, and spinal cord trauma often result in permanent disabilities because adult CNS neurons only exhibit limited axon regeneration. The brain has a surprising intrinsic capability of recovering itself after injury. However, the hostile extrinsic microenvironment significantly hinders axon regeneration. Recent advances have indicated that the inactivation of intrinsic regenerative pathways plays a pivotal role in the failure of most adult CNS neuronal regeneration. Particularly, substantial evidence has convincingly demonstrated that the mechanistic target of rapamycin (mTOR) signaling is one of the most crucial intrinsic regenerative pathways that drive axonal regeneration and sprouting in various CNS injuries. In this review, we will discuss the recent findings and highlight the critical roles of mTOR pathway in axon regeneration in different types of CNS injury. Importantly, we will demonstrate that the reactivation of this regenerative pathway can be achieved by blocking the key mTOR signaling components such as phosphatase and tensin homolog (PTEN). Given that multiple mTOR signaling components are endogenous inhibitory factors of this pathway, we will discuss the promising potential of RNA-based therapeutics which are particularly suitable for this purpose, and the fact that they have attracted substantial attention recently after the success of coronavirus disease 2019 vaccination. To specifically tackle the blood-brain barrier issue, we will review the current technology to deliver these RNA therapeutics into the brain with a focus on nanoparticle technology. We will propose the clinical application of these RNA-mediated therapies in combination with the brain-targeted drug delivery approach against mTOR signaling components as an effective and feasible therapeutic strategy aiming to enhance axonal regeneration for functional recovery after CNS injury.

Dysregulation of mTOR Signaling after Brain Ischemia

In this review, we provide recent data on the role of mTOR kinase in the brain under physiological conditions and after damage, with a particular focus on cerebral ischemia. We cover the upstream and downstream pathways that regulate the activation state of mTOR complexes. Furthermore, we summarize recent advances in our understanding of mTORC1 and mTORC2 status in ischemia–hypoxia at tissue and cellular levels and analyze the existing evidence related to two types of neural cells, namely glia and neurons. Finally, we discuss the potential use of mTORC1 and mTORC2 as therapeutic targets after stroke.

Analysis of expression profiles and bioinformatics suggests that plasma exosomal circular RNAs may be involved in ischemic stroke in the Chinese Han population

Circular RNAs (circRNAs) have been confirmed to be associated with ischemic stroke(IS), but the involvement of exosomal circRNAs in plasma still needs to be extensively discussed. Therefore, we aimed to investigate the expression profile of exosomal circRNAs in plasma and the potential roles and mechanisms of exosomal circRNAs in the pathogenesis of ischemic stroke in the Chinese Han population. In this study, the plasma exosomal circRNA expression profiles of three IS patients and three healthy controls were analyzed using circRNA sequencing. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and circRNA-miRNA-mRNA regulatory network analysis were performed for the aberrantly expressed genes. Protein-protein interaction (PPI) networks and molecular complex detection algorithms (MCODEs) were analyzed by STRING and Cystoscope for functional annotation and construction, respectively. RNA-Seq analysis revealed that a total of 3540 circRNAs were aberrantly expressed in exosomes, 1177 circRNAs were significantly upregulated, and 2363 circRNAs were downregulated in IS patients compared to healthy controls. Bioinformatics analysis revealed that the parental genes of differentially expressed circRNAs as well as the mRNAs predicted in the circRNA-miRNA-mRNA regulatory network are enriched for signaling pathways associated with IS pathology, such as the MAPK signaling pathway, lipid and atherosclerosis, neurotrophic factor signaling pathways, mTOR signaling pathway, the p53 signaling pathway etc. Then, 10 hub genes were identified from the PPI and module networks, including FBXW11, FBXW7, UBE2V2, ANAPC7, CDC27, UBC, CDC5L, POLR2H, POLR2F and RBX1. Overall, the present study provides evidence of an altered plasma exosomal circRNA expression profile and its potential function in IS. Our findings may contribute to the study of the pathogenesis of circRNAs in IS and provide ideas for studying potential diagnostic biomarkers and therapeutic targets for IS.

miR-124 Is Downregulated in Serum of Acute Cerebral Infarct Patients and Shows Diagnostic and Prognostic Value

Acute cerebral infarct (ACI) is a severe subtype of ischemic stroke. microRNAs (miRNAs) are implicated in the pathogenesis of ACI. This study investigated the expression pattern and clinical implication of miR-124 in ACI patients. Serum samples were collected from 108 healthy people and 108 ACI patients at 24 h, 48 h, and 72 h. Serum miR-124 expression was tested using qRT-PCR. The levels of interleukin (IL)-6, IL-8, and C-reactive protein (CRP) were detected using ELISA kits. The correlations between miR-124 expression and infarct classification, infarct size, risk factors, and inflammatory factors were analyzed. The diagnostic efficacy of miR-124 in ACI was analyzed by the ROC curve. ACI patients were assigned to the miR-124 high/low expression group and the incidence of poor prognosis was compared between the two groups. miR-124 expression was poorly expressed in the serum of ACI patients. The area under the ROC curve of miR-124 in the diagnosis of ACI was 0.9527, the specificity was 91.67%, and the sensitivity was 93.52%. miR-124 expression in ACI patients was not affected by infarct classification, infarct size, low-density lipoprotein level, and homocysteine level. miR-124 expression was negatively correlated with IL-6, IL-8, and CRP in ACI patients. Low expression of miR-124 was positively correlated with the poor prognosis of ACI. miR-124 was poorly expressed in the serum of ACI patients and served as a biomarker for the diagnosis and prognosis. This study shall confer a promising novel target for the diagnosis and treatment of ACI.

The p38 MAPK/NF-κB pathway mediates GLT-1 up-regulation during cerebral ischemic preconditioning-induced brain ischemic tolerance in rats

Our previous finding suggests that p38 MAPK contributes to the GLT-1 upregulation during induction of brain ischemic tolerance by cerebral ischemic preconditioning (CIP), however, the underlying mechanism is still unclear. Here, we investigated the molecular mechanisms underlying the CIP-induced GLT-1 upregulation by using Western blotting, Co-immunoprecipitation (Co-IP), electrophoretic mobility shift assay (EMSA) and thionin staining in rat hippocampus CA1 subset. We found that application of BAY11-7082 (an inhibitor of NF-κB), or dihydrokainate (an inhibitor of GLT-1), or SB203580 (an inhibitor of p38 MAPK) could attenuate the CIP-induced neuronal protection in hippocampus CA1 region of rats. Moreover, CIP caused rapid activation of NF-κB, as evidenced by nuclear translocation of NF-κB p50 protein, which led to active p50/p65 dimer formation and increased DNA binding activity. GLT-1 was also increased after CIP. Pretreatment with BAY11-7082 blocked the CIP-induced GLT-1 upregulation. The above results suggest that NF-κB participates in GLT-1 up-regulation during the induction of brain ischemic tolerance by CIP. We also found that pretreatment with SB203580 caused significant reduction of NF-κB p50 protein in nucleus, NF-κB p50/p65 dimer nuclear translocation and DNA binding activity of NF-κB. Together, we conclude that p38 MAPK/NF-κB pathway participates in the mediation of GLT-1 up-regulation during the induction of brain ischemic tolerance induced by CIP.

RVG29-modified microRNA-loaded nanoparticles improve ischemic brain injury by nasal delivery

Effective nose-to-brain delivery needs to be developed to treat neurodegenerative diseases. Regulating miR-124 can effectively improve the symptoms of ischemic brain injury and provide a certain protective effect from brain damage after cerebral ischemia. We used rat models of middle cerebral artery occlusion (t-MCAO) with ischemic brain injury, and we delivered RVG29-NPs-miR124 intranasally to treat neurological damage after cerebral ischemia. Rhoa and neurological scores in rats treated by intranasal administration of RVG29-PEG-PLGA/miRNA-124 were significantly lower than those in PEG-PLGA/miRNA-124 nasal administration and RVG29-PLGA/miRNA-124 nasal administration group treated rats. These results indicate that the nose-to-brain delivery of PLGA/miRNA-124 conjugated with PEG and RVG29 alleviated the symptoms of cerebral ischemia-reperfusion injury. Thus, nasal delivery of RVG29-PEG-PLGA/miRNA-124 could be a new method for treating neurodegenerative diseases.

Mu-Xiang-You-Fang protects PC12 cells against OGD/R-induced autophagy via the AMPK/mTOR signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Mu-Xiang-You-Fang (MXYF) is a classic prescription of Hui medicine. It is composed of five herbs and has been used to treat ischemic stroke for many years. However, the potential pharmacological mechanisms of MXYF remain unclear. The present research is aimed to investigate the protective effect and possible mechanisms of MXYF treatment in an in vitro model of cerebral ischemia-reperfusion injury.

MATERIALS AND METHODS

An oxygen-glucose deprivation and reperfusion (OGD/R) model of PC12 cells was established. The effect of MXYF on the cell viability after OGD/R injury was determined using a cell counting kit (CCK-8) assay. The colorimetric method was used to determine the lactate dehydrogenase (LDH) leakage rate. The calcium concentration was determined by the chemical fluorescence method, and mitochondrial membrane potential was determined using flow cytometry. Monodansylcadaverine (MDC) staining and electron microscopic analysis were then conducted to detect autophagy after oxygen-glucose deprivation and reperfusion in PC12 cells. Immunofluorescence and western blot analyses were used to detect the expression of proteins associated with autophagy.

RESULTS

It was found that MXYF (1, 2, 4 μg/mL) could significantly increase cell viability and mitochondrial membrane potential and decrease the calcium concentration and LDH release rate in PC12 cells. After OGD/R injury in PC12 cells, the number of autophagosomes and autophagolysosome significantly increased. MXYF (4 μg/mL) inhibited the autophagy induced by OGD/R and inhibited the expression of LC3, beclin1, p-AMPK, and ULK1. In contrast, the expression of p-mTOR, p-p70s6k, and p62 was significantly enhanced.

CONCLUSIONS

These findings suggest that MXYF inhibits autophagy after OGD/R-induced PC12 cell injury through the AMPK-mTOR pathway. Thus, MXYF might have therapeutic potential in treating ischemic stroke.