Overexpression of MicroRNA-145 Ameliorates Astrocyte Injury by Targeting Aquaporin 4 in Cerebral Ischemic Stroke. Biomed Res Int. 2017;2017:9530951. [PMID: 29057271 PMCID: PMC5615955 DOI: 10.1155/2017/9530951]

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.

miRNAs in cerebrospinal fluid associated with Alzheimer's disease: A systematic review and pathway analysis using a data mining and machine learning approach

Alzheimer's disease (AD) is the most common type and accounts for 60%-70% of the reported cases of dementia. MicroRNAs (miRNAs) are small non-coding RNAs that play a crucial role in gene expression regulation. Although the diagnosis of AD is primarily clinical, several miRNAs have been associated with AD and considered as potential markers for diagnosis and progression of AD. We sought to match AD-related miRNAs in cerebrospinal fluid (CSF) found in the GeoDataSets, evaluated by machine learning, with miRNAs listed in a systematic review, and a pathway analysis. Using machine learning approaches, we identified most differentially expressed miRNAs in Gene Expression Omnibus (GEO), which were validated by the systematic review, using the acronym PECO-Population (P): Patients with AD, Exposure (E): expression of miRNAs, Comparison (C): Healthy individuals, and Objective (O): miRNAs differentially expressed in CSF. Additionally, pathway enrichment analysis was performed to identify the main pathways involving at least four miRNAs selected. Four miRNAs were identified for differentiating between patients with and without AD in machine learning combined to systematic review, and followed the pathways analysis: miRNA-30a-3p, miRNA-193a-5p, miRNA-143-3p, miRNA-145-5p. The pathways epidermal growth factor, MAPK, TGF-beta and ATM-dependent DNA damage response, were regulated by these miRNAs, but only the MAPK pathway presented higher relevance after a randomic pathway analysis. These findings have the potential to assist in the development of diagnostic tests for AD using miRNAs as biomarkers, as well as provide understanding of the relationship between different pathophysiological mechanisms of AD.

Non-coding RNAs and Aquaporin 4: Their Role in the Pathogenesis of Neurological Disorders

Neurological disorders are a major group of non-communicable diseases affecting quality of life. Non-Coding RNAs (ncRNAs) have an important role in the etiology of neurological disorders. In studies on the genesis of neurological diseases, aquaporin 4 (AQP4) expression and activity have both been linked to ncRNAs. The upregulation or downregulation of several ncRNAs leads to neurological disorder progression by targeting AQP4. The role of ncRNAs and AQP4 in neurological disorders is discussed in this review.

Glymphatic and lymphatic communication with systemic responses during physiological and pathological conditions in the central nervous system

Crosstalk between central nervous system (CNS) and systemic responses is important in many pathological conditions, including stroke, neurodegeneration, schizophrenia, epilepsy, etc. Accumulating evidence suggest that signals for central-systemic crosstalk may utilize glymphatic and lymphatic pathways. The glymphatic system is functionally connected to the meningeal lymphatic system, and together these pathways may be involved in the distribution of soluble proteins and clearance of metabolites and waste products from the CNS. Lymphatic vessels in the dura and meninges transport cerebrospinal fluid, in part collected from the glymphatic system, to the cervical lymph nodes, where solutes coming from the brain (i.e., VEGFC, oligomeric α-syn, β-amyloid) might activate a systemic inflammatory response. There is also an element of time since the immune system is strongly regulated by circadian rhythms, and both glymphatic and lymphatic dynamics have been shown to change during the day and night. Understanding the mechanisms regulating the brain-cervical lymph node (CLN) signaling and how it might be affected by diurnal or circadian rhythms is fundamental to find specific targets and timing for therapeutic interventions.

The role of microRNA-325-3p as a critical player in cell death in NSCs and astrocytes

Neural stem cells (NSCs) are defined by their ability to self-renew and generate various cell types within the nervous system. Understanding the underlying mechanism by which NSCs proliferate and differentiate is crucial for the efficient modulation of in vivo neurogenesis. MicroRNAs are small non-coding RNAs controlling gene expression concerned in post-transcriptional control by blocking messenger RNA (mRNA) translation or degrading mRNA. MicroRNAs play a role as modulators by matching target mRNAs. Recent studies have discussed the biological mechanism of microRNA regulation in neurogenesis. To investigate the role of microRNAs in NSCs and NSC-derived glial cells, we screened out NSC-specific microRNAs by using miRNome-wide screening. Then, we induced downregulation by the sponge against the specific microRNA to evaluate the functional role of the microRNA in proliferation, differentiation, and apoptosis in NSCs and NSC-derived astrocytes. We found that microRNA-325-3p is highly expressed in NSCs and astrocytes. Furthermore, we showed that microRNA-325-3p is a regulator of apoptosis by targeting brain-specific angiogenesis inhibitor (BAI1), which is a receptor for apoptotic cells and expressed in the brain and cultured astrocytes. Downregulation of microRNA-325-3p using an inducible sponge system induced cell death by regulating BAI1 in NSCs and NSC-derived astrocytes. Overall, our findings can provide an insight into the potential roles of NSC-specific microRNAs in brain neurogenesis and suggest the possible usage of the microRNAs as biomarkers of neurodegenerative disease.

Depletion of circ_0006459 protects human brain microvascular endothelial cells from oxygen-glucose deprivation-induced damage through the miR-940/FOXJ2 pathway

BACKGROUND

Multiple circular RNAs (circRNAs) play important roles in ischemic stroke. The present study aims to reveal the role and the mechanism of circ_0006459 in ischemic stroke.

METHODS

Human brain microvascular endothelial cells (HBMECs) were treated with oxygen-glucose deprivation (OGD) to mimic an in vitro ischemic stroke model. RNA expression of circ_0006459, microRNA-940 (miR-940), and forkhead box J2 (FOXJ2) was detected by quantitative real-time polymerase chain reaction. Cell proliferation was analyzed by cell counting kit-8 (CCK-8) and 5-Ethynyl-29-deoxyuridine (EdU) assays. Cell apoptotic rate was quantified by flow cytometry analysis. The protein expression of proliferating cell nuclear antigen (PCNA), clusters of differentiation 6 (CDK6), BCL2-associated x protein (Bax), B-cell lymphoma 2 (Bcl2), interleukin-1β (IL-1β), IL-8, IL-18 and tumor necrosis factor-α (TNF-α) was analyzed by Western blotting. The regulatory relationships among circ_0006459, miR-940, and F 《》 OXJ2 were identified by dual-luciferase reporter assay, RNA immunoprecipitation assay, and RNA pull-down assay.

RESULTS

Circ_0006459 and FOXJ2 expression were significantly upregulated, whereas miR-940 expression was downregulated in HBMECs after OGD. Circ_0006459 depletion assuaged OGD-induced inhibition in cell proliferation and promotion in cell apoptosis and inflammation in HBMECs. Circ_0006459 acted as a sponge for miR-940, and miR-940 targeted FOXJ2 in HBMECs. Besides, miR-940 silencing or FOXJ2 overexpression relieved circ_0006459 knockdown-induced promotion in cell proliferation and inhibition in cell apoptosis and inflammation in OGD-induced HBMECs. Further, circ_0006459 depletion decreased FOXJ2 protein expression by interacting with miR-940.

CONCLUSION

Depletion of circ_0006459 protected human brain microvascular endothelial cells from oxygen-glucose deprivation-induced damage through miR-940/FOXJ2 pathway, providing a promising therapeutic target for ischemic stroke.

Peripheral origin exosomal microRNAs aggravate glymphatic system dysfunction in diabetic cognitive impairment

Cognitive dysfunction is one of the common central nervous systems (CNS) complications of diabetes mellitus, which seriously affects the quality of life of patients and results in a huge economic burden. The glymphatic system dysfunction mediated by aquaporin-4 (AQP4) loss or redistribution in perivascular astrocyte endfeet plays a crucial role in diabetes-induced cognitive impairment (DCI). However, the mechanism of AQP4 loss or redistribution in the diabetic states remains unclear. Accumulating evidence suggests that peripheral insulin resistance target tissues and CNS communication affect brain homeostasis and that exosomal miRNAs are key mediators. Glucose and lipid metabolism disorder is an important pathological feature of diabetes mellitus, and skeletal muscle, liver and adipose tissue are the key target insulin resistance organs. In this review, the changes in exosomal miRNAs induced by peripheral metabolism disorders in diabetes mellitus were systematically reviewed. We focused on exosomal miRNAs that could induce low AQP4 expression and redistribution in perivascular astrocyte endfeet, which could provide an interorgan communication pathway to illustrate the pathogenesis of DCI. Furthermore, the mechanisms of exosome secretion from peripheral insulin resistance target tissue and absorption to the CNS were summarized, which will be beneficial for proposing novel and feasible strategies to optimize DCI prevention and/or treatment in diabetic patients.

Regulation of Glial Function by Noncoding RNA in Central Nervous System Disease

Non-coding RNAs (ncRNAs) are a class of functional RNAs that play critical roles in different diseases. NcRNAs include microRNAs, long ncRNAs, and circular RNAs. They are highly expressed in the brain and are involved in the regulation of physiological and pathophysiological processes of central nervous system (CNS) diseases. Mounting evidence indicates that ncRNAs play key roles in CNS diseases. Further elucidating the mechanisms of ncRNA underlying the process of regulating glial function that may lead to the identification of novel therapeutic targets for CNS diseases.

microRNA as a therapeutic for ischemic stroke

microRNA (miRNA) are important regulators of gene expression. miRNA have the potential as a treatment to modulate genes, pathways and cells involved in ischemic stroke. In this review, we specifically present miRNA in stroke as a treatment to decrease thrombosis, reduce blood brain barrier (BBB) disruption and hemorrhagic transformation (HT), modulate inflammation, and modify angiogenesis. miRNA as a treatment for stroke is an emerging area with evidence from animal studies demonstrating its potential. While no miRNA is currently approved for human use, several have shown promise in clinical trials to treat medical conditions, such as miR-122 for hepatitis C. The role of miRNA as a treatment for specific applications in ischemic stroke is presented including a discussion of the benefits and barriers of miRNA as a treatment, and directions for future advancement.

Sodium Danshensu protects against oxygen glucose deprivation/reoxygenation-induced astrocytes injury through regulating NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome and tuberous sclerosis complex-2 (TSC2)/mammalian target of rapamycin (mTOR) pathways

BACKGROUND

Cerebral ischemic stroke is a serious condition with high incidence, mortality, and associated disability. Currently, effective therapeutic options are available for ischemic stroke are limited. Accumulating evidence indicates that sodium Danshensu, mono sodium compound derived from Salvia miltiorrhiza, plays protective roles in ischemic stroke. However, the underlying protective mechanism of sodium Danshensu in cerebral ischemic stroke remains unknown.

METHODS

In the current study, we explored the role and mechanism of sodium Danshensu on astrocytes exposed to oxygen-glucose deprivation/reoxygenation (OGD/R), which mimics the process of ischemia-reperfusion. The impact of sodium Danshensu on cell viability and apoptosis after OGD/R were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-dophenyl tetrazolium bromide (MTT) assay and flow cytometry. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot were used to detect the expression of target messenger RNA (mRNA) and proteins associated with apoptosis and autophagy. The release of lactate dehydrogenase (LDH) was determined, and the production of proinflammatory cytokines were detected using enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

It was found that sodium Danshensu could significantly increase cell viability and decrease LDH release and apoptosis. Besides, it inhibited the production of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. Sodium Danshensu also dose-dependently decreased protein and mRNA levels of nucleotide binding oligomerization NOD-like receptor pyrin domain containing 3 (NLRP3) and high mobility group box 1 (HMGB1), which play a crucial role in promoting ischemic stroke-induced cell injury. Moreover, sodium Danshensu dose-dependently upregulated Beclin 1 expression, downregulated P62 protein expression, and further increased LC3B-II/LC3B-I ratio through inducing autophagy in astrocytes. Additionally, we noticed that sodium Danshensu dose-dependently increased tuberous sclerosis complex-2 (TSC2) protein expression, while significantly reduced the levels of mammalian target of rapamycin (mTOR) in the presence of OGD/R insult.

CONCLUSIONS

These findings suggest that sodium Danshensu protects against OGD/R-induced injury by modulating the NLRP3 inflammasome and TSC2/mTOR pathways.

Neuroprotective effect of the Nrf2/ARE/miRNA145-5p signaling pathway in the early phase of spinal cord injury

AIMS

Spinal cord injury (SCI) is a debilitating neurological condition often associated with chronic neuroinflammation and redox imbalance. Oxidative stress is one of the main hallmark of secondary injury of SCI which is tightly regulated by nuclear factor E2-related factor 2/antioxidant response element (Nrf2/ARE) signaling. In this study, we aimed at investigating the interplay between inflammation-related miRNAs and the Nrf2 pathway in animal model of SCI.

MATERIALS AND METHODS

The expression of selected four validated miRNA-target pairs (miRNA223-3p, miRNA155-5p, miRNA145-5p, and miRNA124-3p) was examined at different time points (6 h, 12 h, 1 day, 3 day and 7 day) after SCI. Further, using GFAP-specific kelch-like ECH-associated protein 1 deletion (Keap1-/-) and whole-body Nrf2-/- knockout mice, we investigated the potential interplay between each miRNA and the Keap1/Nrf2 signaling system.

KEY FINDINGS

The expression of all miRNAs except miRNA155-5p significantly increased 24 h after SCI and decreased after 7 days. Interestingly, Keap1-/- mice only showed significant increase in the miRNA145-5p after 24 h SCI compared to the WT group. In addition, Keap1-/- mice showed significant decrease in CXCL10/12 (CXCL12 increased in Nrf2-/- mice), and TNF-α, and an increase in Mn-SOD and NQO-1 (Mn-SOD and NQO-1 decreased in Nrf2-/- mice) compared to WT mice.

SIGNIFICANCE

Our results suggest that astrocytic hyperactivation of Nrf2 exert neuroprotective effects at least in part through the upregulation of miRNA145-5p, a negative regulator of astrocyte proliferation, and induction of ARE in early phase of SCI. Further studies are needed to investigate the potential interplay between Nrf2 and miRNA145-5p in neuroinflammatory condition.

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.

Roles of Micro Ribonucleic Acids in Astrocytes After Cerebral Stroke

Cerebral stroke is one of the highest-ranking causes of death and the leading cause of disability globally, particularly with an increasing incidence and prevalence in developing countries. Steadily more evidence has indicated that micro ribonucleic acids (miRNAs) have important regulatory functions in gene transcription and translation in the course of cerebral stroke. It is beyond arduous to understand the pathophysiology of cerebral stroke, due in part to the perplexity of influencing the network of the inflammatory response, brain edema, autophagy and neuronal apoptosis. The recent research shows miRNA plays a key role in regulating aquaporin 4 (AQP4), and many essential pathological processes after cerebral stroke. This article reviews the recent knowledge on how miRNA influences the inflammatory response, brain edema, infarction size, and neuronal injury after cerebral stroke. In addition, some miRNAs may serve as potential biomarkers in stroke diagnosis and therapy since the expression of some miRNAs in the blood is stable after cerebral stroke.

Downregulation of long non-coding RNAs in patients with bipolar disorder

The abnormal function of signaling cascades is currently a candidate in the pathophysiology of bipolar disorder (BD). One of the factors involved in activating these signals is oxidative stress. Some long non-coding RNAs (lncRNA) are involved in the oxidative stress. In this study, we compared expression levels of lincRNA-p21, lincRNA-ROR, and lincRNA-PINT in the peripheral blood mononuclear cells (PBMC) from BD patients (n = 50) and healthy individuals (n = 50). Expression levels of lincRNA-p21, lincRNA-ROR, and lincRNA-PINT were significantly reduced in patients with BD compared to controls. In sex-based analyses, down-regulation of these lncRNAs was revealed only in male BD patients compared to male healthy subjects. Also, in BD patients, all three lncRNAs showed a significant pairwise positive correlation in expression level. The area under curve values for lincRNA-p21, lincRNA-ROR, and lincRNA-PINT was 0.66, 0.75, and 0.66, respectively. Thus, the ROC curve analysis showed that lncRNA-ROR might serve as a diagnostic biomarker for distinguishing between BD patients and controls. Altogether, the current study proposes a role for lincRNA-p21, lincRNA-ROR, and lincRNA-PINT in the pathogenesis of bipolar disorder. Moreover, the peripheral expression of these lncRNAs might be useful as potential biomarkers for BD.

Profile and Functional Prediction of Plasma Exosome-Derived CircRNAs From Acute Ischemic Stroke Patients

Stroke is one of the major causes of death and long-term disability, of which acute ischemic stroke (AIS) is the most common type. Although circular RNA (circRNA) expression profiles of AIS patients have been reported to be significantly altered in blood and peripheral blood mononuclear cells, the role of exosome-containing circRNAs after AIS is still unknown. Plasma exosomes from 10 AIS patients and 10 controls were isolated, and through microarray and bioinformatics analysis, the profile and putative function of circRNAs in the plasma exosomes were studied. A total of 198 circRNAs were differentially quantified (|log2 fold change| ≥ 1.00, p < 0.05) between AIS patients and controls. The levels of 12 candidate circRNAs were verified by qRT-PCR, and the quantities of 10 of these circRNAs were consistent with the data of microarray. The functions of host genes of differentially quantified circRNAs, including RNA and protein process, focal adhesion, and leukocyte transendothelial migration, were associated with the development of AIS. As a miRNA sponge, differentially quantified circRNAs had the potential to regulate pathways related to AIS, like PI3K-Akt, AMPK, and chemokine pathways. Of 198 differentially quantified circRNAs, 96 circRNAs possessing a strong translational ability could affect cellular structure and activity, like focal adhesion, tight junction, and endocytosis. Most differentially quantified circRNAs were predicted to bind to EIF4A3 and AGO2—two RNA-binding proteins (RBPs)—and to play a role in AIS. Moreover, four of ten circRNAs with verified levels by qRT-PCR (hsa_circ_0112036, hsa_circ_0066867, hsa_circ_0093708, and hsa_circ_0041685) were predicted to participate in processes of AIS, including PI3K-Akt, AMPK, and chemokine pathways as well as endocytosis, and to be potentially useful as diagnostic biomarkers for AIS. In conclusion, plasma exosome-derived circRNAs were significantly differentially quantified between AIS patients and controls and participated in the occurrence and progression of AIS by sponging miRNA/RBPs or translating into proteins, indicating that circRNAs from plasma exosomes could be crucial molecules in the pathogenesis of AIS and promising candidates as diagnostic biomarkers and therapeutic targets for the condition.

MicroRNA-Enriched Exosomes from Different Sources of Mesenchymal Stem Cells Can Differentially Modulate Functions of Immune Cells and Neurogenesis

Adult Mesenchymal stem cells-derived exosomes carry several biologically active molecules that play prominent roles in controlling disease manifestations. The content of these exosomes, their functions, and effect on the immune cells may differ depending on their tissue sources. Therefore, in this study, we purified the exosomes from three different sources and, using the RNA-Seq approach, highly abundant microRNAs were identified and compared between exosomes and parental cells. The effects of exosomes on different immune cells were studied in vitro by incubating exosomes with PBMC and neutrophils and assessing their functions. The expression levels of several miRNAs varied within the different MSCs and exosomes. Additionally, the expression profile of most of the miRNAs was not similar to that of their respective sources. Exosomes isolated from different sources had different abilities to induce the process of neurogenesis and angiogenesis. Moreover, these exosomes demonstrated their varying effect on PBMC proliferation, neutrophil survival, and NET formation, highlighting their versatility and broad interaction with immune cells. The knowledge gained from this study will improve our understanding of the miRNA landscape of exosomes from hMSCs and provide a resource for further improving our understanding of exosome cargo and their interaction with immune cells.

Emerging Impact of Non-coding RNAs in the Pathology of Stroke

Ischemic stroke (IS) is an acute cerebral vascular event with high mortality and morbidity. Though the precise pathophysiologic routes leading to this condition are not entirely clarified, growing evidence from animal and human experiments has exhibited the impact of non-coding RNAs in the pathogenesis of IS. Various lncRNAs namely MALAT1, linc-SLC22A2, linc-OBP2B-1, linc_luo_1172, linc-DHFRL1-4, SNHG15, linc-FAM98A-3, H19, MEG3, ANRIL, MIAT, and GAS5 are possibly involved in the pathogenesis of IS. Meanwhile, lots of miRNAs contribute in this process. Differential expression of lncRNAs and miRNAs in the sera of IS patients versus unaffected individuals has endowed these transcripts the aptitude to distinguish at risk patients. Despite conduction of comprehensive assays for evaluation of the influence of lncRNAs/miRNAs in the pathogenesis of IS, therapeutic impacts of these transcripts in IS have not been clarified. In the present paper, we review the impact of lncRNAs/miRNAs in the pathobiology of IS through assessment of evidence provided by human and animal studies.

MicroRNA-424 alleviates neurocyte injury by targeting PDCD4 in a cellular model of cerebral ischemic stroke

Cerebral ischemic stroke is the primary cause of stroke-associated mortality and disability, and current therapeutic options are limited and ineffective. The present study aimed to investigate the potential of apoptotic therapy and the role of microRNA (miR)-424 in cerebral ischemic stroke. PC12 cells, a cloned cell line from rat adrenal pheochromocytoma, were treated with CoCl₂ to construct a cellular ischemia model. mRNA and protein levels of programmed cell death protein 4 (PDCD4), Bcl-2, Bax, caspase-3, PI3K and AKT were evaluated using reverse transcription-quantitative PCR and western blot analyses, respectively. Cell Counting Kit-8 assays were performed to examine cell viability in the ischemia model. Flow cytometry was conducted to evaluate the apoptosis of ischemic cells. Furthermore, a luciferase assay was performed to verify the target gene of miR-424. It was revealed that the expression level of miR-424 was downregulated in the ischemia model, while the expression of PDCD4 was upregulated. Moreover, the expression of miR-424 was increased after treatment with miR-424 mimics. The mRNA and protein expression of PDCD4 was upregulated after transfection with pcDNA3.1-PDCD4. PDCD4 was predicted and demonstrated to be a target of miR-424. Notably, overexpression of miR-424 increased cell viability and inhibited apoptosis in the ischemia model, which was reversed by co-treatment with pcDNA3.1-PDCD4. Furthermore, overexpression of miR-424 regulated the expression of PDCD4, Bax, Bcl-2, phosphorylated-PI3K/AKT and caspase-3, which was restored after co-transfection with pcDNA3.1-PDCD4. Collectively, the results indicated that miR-424 regulated the progression of cerebral ischemic stroke in a cellular model by targeting PDCD4.

Downregulation of MicroRNA-145-5p in Activated Microglial Exosomes Promotes Astrocyte Proliferation by Removal of Smad3 Inhibition

In spinal cord injury, microglial activation plays an important role during the inflammatory process. Specifically, the cellular and molecular interactions between microglia and astrocytes are of critical importance. Cells can communicate with each other through the substances carried by exosomes, and overproliferated astrocytes would create a physical and chemical barrier that prevents neurite regeneration, thereby interfering with functional recovery. On the other hand, Smad3 is an important factor in the proliferation, migration, and apoptosis of astrocytes. In this study, supernatant and purified exosomes were collected from LPS-treated microglia and co-cultured with astrocytes. The results showed that astrocytic proliferation was promoted with higher levels of Smad3. Furthermore, miRNA sequencing analysis was performed on microglial exosomes after inflammation. The results revealed a differential expression of miR-145-5p in the exosomes. The Dual-Luciferase assay showed that miR-145-5p could bind to Smad3 mRNA and regulate the levels of Smad3 protein at the post-transcriptional level. Subsequently, exosomes were transfected with miR-145-5p mimics, and astrocytes after mechanical injury were cultured with these exosomes for 24 h. The levels of Smad3 and phosphor-Smad3 proteins were analyzed by western blot and qRT-PCR. CCK8 and flow cytometry showed lower proliferation of astrocytes after co-culturing with the exosomes transfected with the miR-145-5p mimic. This study finds that miR-145-5p was found to be a negative regulator of astrocyte proliferation, and that its downregulation promotes smad3 activity and thus astrocyte proliferation.

microRNA-1906 protects cerebral ischemic injury through activating Janus kinase 2/signal transducer and activator of transcription 3 pathway in rats

This study aimed to investigate the effects of miR-1906 on cerebral ischemic injury and its underlying mechanisms. After 24 h of reperfusion, neurological deficit scores, brain water content and infarct volume were measured. Neuronal apoptosis was detected by using terminal dexynucleotidyl transferase-mediated dUTP nick end labeling assay. Hematoxylin-eosin staining was used to evaluate the histopathological damage of neurons. The expression of miR-1906 was detected by qRT-PCR. And the expressions of Bax, Bcl-2, caspase-3, Janus kinase 2 (JAK2), p-JAK2, signal transducer and activator of transcription 3 (STAT3) and p-STAT3 were measured by western blot. Furthermore, the levels of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β) and IL-6 were measured by ELISA. We found that miR-1906 expression was significantly decreased in the cerebral ischemia injury rats. miR-1906 decreased neurological score, infarct volume, brain water content, neuronal apoptosis and inflammatory factors (TNF-α, IL-6 and IL-1β) expression. In addition, miR-1906 promoted the phosphorylation of JAK2 and STAT3. After treating with JAK2/STAT3 pathway inhibitor AG490, the phosphorylation of JAK2 and STAT3 was inhibited and the effects of miR-1906 on neurological score, infarct volume, brain water content, neuronal apoptosis and inflammatory factors were reversed. miR-1906 could protect cerebral ischemic injury through activating the JAK2/STAT3 pathway in rats.

Role of Aquaporins in Inflammation-a Scientific Curation

Inflammation is a universal response mechanism existing as inter-communicator of biological systems. Uncontrolled or dysregulated inflammation addresses chronic low-grade effects eventually resulting in multimorbidity. Active solute transport across the membrane establishes varying osmotic gradients. Aquaporins (AQPs) are a class of critical ubiquitously expressed transmembrane proteins that aid in fluid and small solute transport via facilitated diffusion over established osmotic gradients. Numerous significant data features the biological functions of AQPs rendering them as an appropriate biomarker of health and diseases. Besides their physiological role in well-balanced inflammatory responses, it is worth noting the dysregulation of AQPs during any undesirable inflammatory event. Most literature to date clearly sets out AQPs as potential drug targets instigating AQP-based therapies. In light of this conception, the current review provides a compendious overview on the propitious and portentous out-turns of AQPs under inflammation.

Association of lncRNA with regulatory molecular factors in brain and their role in the pathophysiology of schizophrenia

Schizophrenia is one of the most agonizing neurodegenerative diseases of the brain. Research undertaken to understand the molecular mechanism of this disease has undergone a transition and currently more emphasis is put on long noncoding RNA (lncRNA). High expression level of lncRNA in the brain contributes to several molecular pathways essential for the proper functioning of neurons, neurotransmitters, and synapses, that are often found dysfunctional in Schizophrenia. Recently, the association of lncRNA with various molecular factors in the brain has been explored to a considerably large extent. This review comprehends the significance of lncRNA in causing profound regulatory effect in the brain and how any alterations to the association of lncRNA with regulatory proteins, enzymes and other noncoding RNA could contribute to the aetiology of Schizophrenia.

Aquaporin 4 and brain-related disorders: Insights into its apoptosis roles

Brain-related disorders are leading global health problems. Various internal and external factors are involved in the progression of brain-related disorders. Inflammatory pathways, oxidative stresses, apoptosis, and deregulations of various channels are critical players in brain-related disorder pathogenesis. Among these players, aquaporins (AQP) have critical roles in various physiological and pathological conditions. AQPs are water channel molecules that permit water to cross the hydrophobic lipid bilayers of cellular membranes. AQP4 is one of the important members of AQP family. AQPs are involved in controlling apoptosis pathways in brain-related disorders. In this regard, several reports have evaluated the pathological effects of AQP4 by targeting the apoptosis-related processes in brain-related disorders. Here, for the first time, we highlight the impact of AQP4 on apoptosis-related processes in brain-related disorders.

Propofol maintains Th17/Treg cell balance and reduces inflammation in rats with traumatic brain injury via the miR‑145‑3p/NFATc2/NF‑κB axis

Propofol is a commonly used intravenous anesthetic. The aim of the study was to examine the mechanism of propofol in traumatic brain injury (TBI) by regulating interleukin (IL)‑17 activity and maintaining the Th17/Treg balance. A rat model with moderate TBI was established using the weight‑drop method. Rats with TBI were regularly injected with propofol and their brain injuries were monitored. The peripheral blood of rats was collected to measure the Th17/Treg ratio. MicroRNA (miR)‑145‑3p expression was detected in the brain tissues of rats and antagomiR‑145‑3p was injected into the lateral ventricles of their brains to verify the effect of miR‑145‑3p on brain injury. The downstream target of miR‑145‑3p was predicted. The targeting relationship between miR‑145‑3p and nuclear factor of activated T cells c2 (NFATc2) was confirmed. NFATC2 expression and phosphorylation of NF‑κB pathway‑related proteins were measured. Propofol alleviated brain injury in rats with TBI and maintained the Th17/Treg balance. Propofol upregulated miR‑145‑3p expression in rat brains, while the inhibition of miR‑145‑3p reversed the effect of propofol on brain injury. A binding relationship was observed between miR‑145‑3p and NFATc2. Furthermore, propofol decreased the phosphorylation of p65 and IκBα, and inhibited activation of the NF‑κB pathway in the brains of rats with TBI. In conclusion, propofol maintained Th17/Treg balance and reduced inflammation in the rats with TBI via the miR‑145‑3p/NFATc2/NF‑κB axis.

Long Noncoding RNA SNHG14 Promotes Ischemic Brain Injury via Regulating miR-199b/AQP4 Axis

BACKGROUND

Ischemic stroke is the leading cause of disability worldwide. Long noncoding RNAs (lncRNAs) play important roles in the pathogenesis of cerebral ischemia. This study aimed to investigate the role and mechanism of lncRNA small nucleolar RNA host gene 14 (SNHG14) in ischemic brain injury.

METHODS

Cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) in mice. The expression of SNHG14 in MCAO mouse model was detected by quantitative real-time PCR (qRT-PCR). The levels of SNHG14, microRNA-199b (miR-199b) and aquaporin 4 (AQP4) in oxygen-glucose deprivation (OGD)-stimulated BV2 cells were determined by qRT-PCR or western blot assay. Cell proliferation and apoptosis were assessed by Cell Counting Kit-8 (CCK-8) assay and flow cytometry. The levels of pro-inflammatory cytokines were measured by enzyme-linked immunosorbent assay (ELISA). The levels of oxidative stress markers were examined using commercial kits. The relationships among SNHG14, miR-199b and AQP4 were confirmed by dual-luciferase reporter assay, RNA immunoprecipitation assay and RNA pull-down assay.

RESULTS

SNHG14 was up-regulated in MCAO mouse model. Depletion of SNHG14 lessened cerebral ischemia in MCAO mouse model. SNHG14 silencing inhibited inflammation and oxidative stress in OGD-exposed BV2 cells. MiR-199b level was decreased, while AQP4 level was increased in OGD-treated BV2 cells. Knockdown of miR-199b reversed the effect of SNHG14 knockdown on ischemic damage in OGD-stimulated BV2 cells. Moreover, AQP4 overexpression abolished the effect of miR-199b on ischemic injury in OGD-treated BV2 cells. Furthermore, SNHG14 indirectly regulate AQP4 expression by sponging miR-199b.

CONCLUSIONS

Knockdown of SNHG14 attenuated ischemic brain injury by inhibiting inflammation and oxidative stress through the miR-199b/AQP4 axis.

Retracted: Sevoflurane improves nerve regeneration and repair of neurological deficit in brain damage rats via microRNA-490-5p/CDK1 axis

BACKGROUND

Sevoflurane (Sevo) is neuroprotective in brain damage, thus our objective was to further investigate the impact of Sevo treatment on nerve regeneration and repair of neurological deficit in brain damage rats by regulating miR-490-5p and cyclin-dependent kinases 1 (CDK1).

METHODS

The rat middle cerebral artery occlusion model was established. miR-490-5p and CDK1 levels in brain tissues were tested. The behavioral changes, the number of glial fibrillary acidic protein (GFAP) positive cells, ionized calcium-binding adapter molecule-1 (Iba-1) and Nestin mRNA expression, the survival and apoptosis of neurons in peripheral tissues of infarct areas were detected by a series of assays. Furthermore, the target relationship between miR-490-5p and CDK1 was verified.

RESULTS

miR-490-5p was reduced and CDK1 was raised in brain tissues of brain damage rats. Sevo raised miR-490-5p and decreased CDK1 to improve neurological deficits, reduce apoptotic neurons, suppress expression levels of GFAP and Iba-1, and increase Nestin expression and the number of surviving neurons in peripheral tissue in infarct area, and alleviate the pathological changes of brain tissues of brain damage rats. CDK1 was negatively regulated by miR-490-5p.

CONCLUSION

Our study presents that Sevo treatment is involved in neurogenesis and repair of neurological deficit of brain damage rats via up-regulating miR-490-5p and inhibiting CDK1.

RNA Localization and Local Translation in Glia in Neurological and Neurodegenerative Diseases: Lessons from Neurons

Cell polarity is crucial for almost every cell in our body to establish distinct structural and functional domains. Polarized cells have an asymmetrical morphology and therefore their proteins need to be asymmetrically distributed to support their function. Subcellular protein distribution is typically achieved by localization peptides within the protein sequence. However, protein delivery to distinct cellular compartments can rely, not only on the transport of the protein itself but also on the transport of the mRNA that is then translated at target sites. This phenomenon is known as local protein synthesis. Local protein synthesis relies on the transport of mRNAs to subcellular domains and their translation to proteins at target sites by the also localized translation machinery. Neurons and glia specially depend upon the accurate subcellular distribution of their proteome to fulfil their polarized functions. In this sense, local protein synthesis has revealed itself as a crucial mechanism that regulates proper protein homeostasis in subcellular compartments. Thus, deregulation of mRNA transport and/or of localized translation can lead to neurological and neurodegenerative diseases. Local translation has been more extensively studied in neurons than in glia. In this review article, we will summarize the state-of-the art research on local protein synthesis in neuronal function and dysfunction, and we will discuss the possibility that local translation in glia and deregulation thereof contributes to neurological and neurodegenerative diseases.

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.

LncRNA NEAT1/miR-128-3p/AQP4 axis regulating spinal cord injury-induced neuropathic pain progression

BACKGROUND

Neuropathic pain (NP) is the comorbidity in spinal cord injury(SCI), which is the hardest to cure. Non-coding RNA dysregulations are related to the development of NP. NEAT1(nuclear paraspeckle assembly transcript 1) is a new type of lncRNA. This study explores the role and specific mechanism of NEAT1 in SCI-mediated NP.

METHODS

Firstly, the NEAT1 expression in SCI rats and the control group was detected with RT-PCR to analyze the relationship between NEAT13 and NP symptoms. Then, SCI rats were intrathecally injected with NEAT13 overexpressing and knocking down lentiviruses. Afterward, ELISA was utilized to assess the expression of IL-6, IL-1β and TNFα in rats. Subsequently, immunohistochemistry was adopted to verify the activation of microglial cells. After that, bioinformatics analysis was employed to further predict the downstream target genes of NEAT1, while RT-PCR and Western blot were conducted to determine the relative expression of miR-128-3p and aquaporin-4(AQP4). Meanwhile, a dual-luciferase reporter assay was performed to further study the targeting relationship between NEAT1 and miR-128-3p, and miR-128-3p and AQP4.

RESULTS

SCI rats showed distinctly higher NEAT1 expression compared with that of the control group. ELISA experiment confirmed that the over-expression of NEAT1 enhanced the expression of IL-6, IL-1β, and TNFα in SCI rats. Other related mechanism studies revealed that NEAT13 targeted and inhibited miR-128-3p as its competing endogenous RNA (ceRNA), and enhanced AQP4 expression, while miR-128-3p targeted AQP4 to regulate its expression.

SUMMARY

NEAT1 affects AQP4 signaling pathway to alleviate the spinal cord injury-induced NP via promoting miR-128-3p expression.

Inhibition of LncRNA MALAT1 Attenuates Cerebral Ischemic Reperfusion Injury via Regulating AQP4 Expression

Stroke is one of the leading causes of mortality and disability worldwide. Long noncoding RNAs (lncRNAs) including MALAT1 have been shown to have critical roles in cerebral ischemia reperfusion injury (CIRI). However, the underlying mechanism of MALAT1 in CIRI has not been elucidated. The present study aimed to investigate the function and potential regulatory mechanism of MALAT1 in cerebral ischemic reperfusion injury. We established the middle cerebral artery occlusion (MCAO) model and oxygen-glucose deprivation/reoxygenation (OGD/RX) model in vivo and in vitro, and then Cell Counting Kit-8 (CCK-8), RT-qPCR, flow cytometry analysis, lactate dehydrogenase (LDH) analysis, and 2,3,5-triphenyltetrazolium chloride (TTC) staining were used to examine cell viability, MALAT1, aquaporin-4 (AQP4) expression, LDH release, and infarct volume, respectively. The level of AQP4 was remarkably upregulated in CIRI 24 h/48 h or OGD/RX 24 h/48 h compared with the sham group. Knockdown of AQP4 could alleviate OGD/RX-induced injury through enhancing cell viability and reducing LDH release and the rate of apoptotic cells. Furthermore, we found that MALAT1 was also increased in OGD/RX 24 h/48 h and silencing of MALAT1 could decrease AQP4. Inhibition of MALAT1 could also protect OGD/RX-induced injury, while the protective effect of MALAT1 siRNA on cerebral ischemic reperfusion was disappeared after transfection with AQP4 plasmid, indicating that MALAT1 may play a protective role in brain stroke through regulating AQP4. Taken together, our study provides evidence that MALAT1 is involved in ischemic stroke by inhibiting AQP4. Therefore, MALAT1 may serve as a potential target for therapeutic intervention in ischemic brain injury.

Astrocytes in the regulation of cerebrovascular functions

Astrocytes are the most numerous type of neuroglia in the brain and have a predominant influence on the cerebrovascular system; they control perivascular homeostasis, the integrity of the blood-brain barrier, the dialogue with the peripheral immune system, the transfer of metabolites from the blood, and blood vessel contractility in response to neuronal activity. These regulatory processes occur in a specialized interface composed of perivascular astrocyte extensions that almost completely cover the cerebral blood vessels. Scientists have only recently started to study how this interface is formed and how it influences cerebrovascular functions. Here, we review the literature on the astrocytes' role in the regulation of the cerebrovascular system. We cover the anatomy and development of the gliovascular interface, the known gliovascular functions, and molecular factors, the latter's implication in certain pathophysiological situations, and recent cutting-edge experimental tools developed to examine the astrocytes' role at the vascular interface. Finally, we highlight some open questions in this field of research.

Role of the neurovascular unit in the process of cerebral ischemic injury

Cerebral ischemic injury exhibits both high morbidity and mortality worldwide. Traditional research of the pathogenesis of cerebral ischemic injury has focused on separate analyses of the involved cell types. In recent years, the neurovascular unit (NVU) mechanism of cerebral ischemic injury has been proposed in modern medicine. Hence, more effective strategies for the treatment of cerebral ischemic injury may be provided through comprehensive analysis of brain cells and the extracellular matrix. However, recent studies that have investigated the function of the NVU in cerebral ischemic injury have been insufficient. In addition, the metabolism and energy conversion of the NVU depend on interactions among multiple cell types, which make it difficult to identify the unique contribution of each cell type. Therefore, in the present review, we comprehensively summarize the regulatory effects and recovery mechanisms of four major cell types (i.e., astrocytes, microglia, brain-microvascular endothelial cells, and neurons) in the NVU under cerebral ischemic injury, as well as discuss the interactions among these cell types in the NVU. Furthermore, we discuss the common signaling pathways and signaling factors that mediate cerebral ischemic injury in the NVU, which may help to provide a theoretical basis for the comprehensive elucidation of cerebral ischemic injury.

Long non‑coding RNA SNHG16 inhibits the oxygen‑glucose deprivation and reoxygenation‑induced apoptosis in human brain microvascular endothelial cells by regulating miR‑15a‑5p/bcl‑2

MicroRNA (miR) 15a-5p can promote ischemia/reperfusion (I/R)-induced apoptosis of cerebral vascular endothelial cells, which is inhibited by long non-coding RNAs (lncRNAs). The present study investigated the potential of lncRNAs targeting miR-15a-5p to regulate oxygen-glucose deprivation and reoxygenation (OGD-R)-induced apoptosis of human brain microvascular endothelial cells (hBMECs). hBMECs were transfected with or without miR-15a-5p or its mutant, together with p-small nucleolar RNA host gene 16 (SNHG16) or its mutant. Following OGD-R, proliferation, apoptosis and miR-15a-5p, SNHG16 and Bcl-2 expression levels were determined using MTT, flow cytometry, reverse transcription-quantitative PCR or western blotting. The potential interaction of SNHG16 with miR-15a-5p was analyzed by pull-down, luciferase and immunoprecipitation assays. OGD-R induced apoptosis of hBMECs and increased miR-15a-5p expression levels in a time-dependent manner. miR-15a-5p overexpression decreased the proliferation of hBMECs and promoted apoptosis by decreasing Bcl-2 expression levels. SNHG16 was pulled-down by miR-15a-5p and anti-Ago2. miR-15a-5p overexpression significantly decreased SNHG16-regulated luciferase activity and hBMEC survival by increasing apoptosis. SNHG16 overexpression decreased miR-15a-5p expression levels in hBMECs. SNHG16 gradually decreased following OGD-R and its overexpression decreased miR-15a-5p expression levels and promoted the proliferation of hBMECs by decreasing apoptosis. SNHG16 enhanced Bcl-2 expression levels in hBMECs, which was abrogated by miR-15a-5p. Bioinformatics suggest that SNHG16 may antagonize the binding of miR-15a-5p to the 3′UTR of Bcl-2 mRNA. These findings suggest that SNHG16 may protect hBMECs from OGD-R-induced apoptosis by antagonizing the miR-15a-5p/bcl-2 axis. Thus, targeting SNHG16-based mechanisms may provide novel therapeutic strategies for treatment of ischemic stroke.

Inhibition of lncRNA LINC00461/miR-216a/aquaporin 4 pathway suppresses cell proliferation, migration, invasion, and chemoresistance in glioma

Long noncoding RNA (lncRNA) LINC00461 (LINC00461) is reported to be related to glioma progression. However, the mechanism of LINC00461 in glioma remains unclear. Expression of LINC00461, miRNA (miR)-216a, and aquaporin 4 (AQP4) was detected using real-time quantitative PCR (RT-qPCR) and western blotting. Proliferation, temozolomide (TMZ) resistance, migration, and invasion were assessed by MTT, colony formation, and transwell assays, respectively. The target binding among miR-216a, LINC00461, and AQP4 was confirmed by the luciferase reporter assay. The tumor growth was monitored in the xenograft experiment. LINC00461 was upregulated, and miR-216a was downregulated in glioma tissues and cells, and LINC00461 upregulation was correlated with large tumor size, higher WHO grade and recurrence, and poor overall survival. LINC00461 knockdown suppressed cell viability, abilities of cell cloning and migration and invasion, and TMZ resistance in glioma. Mechanically, LINC00461 was confirmed to sponge miR-216a to affect AQP4 expression. Rescue assays verified that miR-216a downregulation or AQP4 upregulation abrogated the inhibitory effect of LINC00461 knockdown on cell proliferation, migration, invasion, and TMZ resistance in vitro. Moreover, LINC00461 downregulation blocked the glioma tumor growth in vivo. In conclusion, LINC00461 knockdown inhibits glioma cell proliferation, migration, invasion, and TMZ resistance through miR-216a/AQP4 axis, suggesting LINC00461 as an oncogene in glioma progression.

Extracellular Vesicles Derived from Neural Progenitor Cells--a Preclinical Evaluation for Stroke Treatment in Mice

Stem cells such as mesenchymal stem cells (MSCs) enhance neurological recovery in preclinical stroke models by secreting extracellular vesicles (EVs). Since previous reports have focused on the application of MSC-EVs only, the role of the most suitable host cell for EV enrichment and preclinical stroke treatment remains elusive. The present study aimed to evaluate the therapeutic potential of EVs derived from neural progenitor cells (NPCs) following experimental stroke. Using the PEG technique, EVs were enriched and characterized by electron microscopy, proteomics, rt-PCR, nanosight tracking analysis, and Western blotting. Different dosages of NPC-EVs displaying a characteristic profile in size, shape, cargo protein, and non-coding RNA contents were incubated in the presence of cerebral organoids exposed to oxygen-glucose deprivation (OGD), significantly reducing cell injury when compared with control organoids. Systemic administration of NPC-EVs in male C57BL6 mice following experimental ischemia enhanced neurological recovery and neuroregeneration for as long as 3 months. Interestingly, the therapeutic impact of such NPC-EVs was found to be not inferior to MSC-EVs. Flow cytometric analyses of blood and brain samples 7 days post-stroke demonstrated increased blood concentrations of B and T lymphocytes after NPC-EV delivery, without affecting cerebral cell counts. Likewise, a biodistribution analysis after systemic delivery of NPC-EVs revealed the majority of NPC-EVs to be found in extracranial organs such as the liver and the lung. This proof-of-concept study supports the idea of EVs being a general concept of stem cell–induced neuroprotection under stroke conditions, where EVs contribute to reverting the peripheral post-stroke immunosuppression.

[MicroRNA and their potential role in the pathogenesis of hemorrhagic stroke]

Spontaneous (non-traumatic) intracerebral hemorrhage (ICH), or hemorrhagic stroke, is a common and serious disease with high morbidity and mortality. Current methods of treating hemorrhagic stroke, from conservative to surgical, are insufficient, which justifies the continuation of the study of this condition, including cellular and molecular changes that occur during a stroke. MicroRNAs (miRNAs) are a class of small non-coding RNAs that play an important role in post-transcriptional regulation of gene expression. MicroRNAs are involved in almost all biological processes, including cell proliferation, apoptosis and cell differentiation, and are also key substances in pathophysiological processes in many diseases, and therefore they can be both potential biomarkers and new therapeutic targets in cancer, degenerative and cardiovascular disease. In recent years, a number of studies have been aimed at studying the role of microRNAs in pathophysiological processes in hemorrhagic stroke, such as apoptosis, inflammation, oxidative stress, violation of the blood-brain barrier (BBB) and cerebral edema. The results of the studies demonstrated that changes in miRNA expression may be associated with the prognosis of ICH. In this article, we consider studies related to miRNAs and hemorrhagic stroke, and clarify the complex relationship between them.

LncRNA MALAT1 silencing protects against cerebral ischemia-reperfusion injury through miR-145 to regulate AQP4

BACKGROUND

The present study aimed to verify whether long noncoding RNA (lncRNA) MALAT1 is involved in brain tissue damage induced by ischemia-reperfusion injury, and to explore the mechanism by which MALAT1 regulates aquaporin 4 (AQP4).

METHODS

In this study, we established glucose deprivation (OGD)/reoxygenation (RX) astrocyte cell model and middle cerebral artery occlusion (MCAO)/reperfusion mouse model in vitro and in vivo. Then cell counting kit-8 assay, flow cytometry analysis, Triphenyltetrazolium chloride (TTC) staining, and western blotting were used to determine cell viability, cell apoptosis, cerebral infarction volume, and the abundance of AQP4, respectively.

RESULTS

We found that the level of MALAT1 was significantly upregulated in both the MCAO/reperfusion model and OGD/RX model. Knockdown of MALAT1 increased cell viability and reduced cell apoptosis in MA-C cells, while an AQP4 siRNA combined with a siRNA targeting MALAT1 could not enhance this effect. Further experiments showed that MALAT1 positively regulated AQP4 expression via miR-145. The MALAT1 siRNA did not alleviate the exacerbation of damage after miR-145 inhibitor action. However, an miR-145 inhibitor reversed the protection effects of MALAT1, indicating that MALAT1 silencing protects against cerebral ischemia-reperfusion injury through miR-145. TTC staining showed that the infracted area of whole brain was significantly attenuated in treated with sh-MALAT1 group in vivo.

CONCLUSION

Taken together, our study confirmed that MALAT1 promotes cerebral ischemia-reperfusion injury by affecting AQP4 expression through competitively binding miR-145, indicating that MALAT1 might be a new therapeutic target for treatment cerebral ischemic stroke.

Regulation of AQP4 in the Central Nervous System

Aquaporin-4 (AQP4) is the main water channel protein expressed in the central nervous system (CNS). AQP4 is densely expressed in astrocyte end-feet, and is an important factor in CNS water and potassium homeostasis. Changes in AQP4 activity and expression have been implicated in several CNS disorders, including (but not limited to) epilepsy, edema, stroke, and glioblastoma. For this reason, many studies have been done to understand the various ways in which AQP4 is regulated endogenously, and could be regulated pharmaceutically. In particular, four regulatory methods have been thoroughly studied; regulation of gene expression via microRNAs, regulation of AQP4 channel gating/trafficking via phosphorylation, regulation of water permeability using heavy metal ions, and regulation of water permeability using small molecule inhibitors. A major challenge when studying AQP4 regulation is inter-method variability. A compound or phosphorylation which shows an inhibitory effect in vitro may show no effect in a different in vitro method, or even show an increase in AQP4 expression in vivo. Although a large amount of variability exists between in vitro methods, some microRNAs, heavy metal ions, and two small molecule inhibitors, acetazolamide and TGN-020, have shown promise in the field of AQP4 regulation.

Calcium sensing receptor exerts a negative regulatory action toward vasopressin-induced aquaporin-2 expression and trafficking in renal collecting duct

Vasopressin (AVP) plays a major role in the regulation of water homeostasis by its antidiuretic action on the kidney, mediated by V2 receptors. An increase in plasma sodium concentration stimulates AVP release, which in turn promotes water reabsorption. Upon binding to the V2 receptors in the renal collecting duct, AVP induces the expression and apical membrane insertion of the aquaporin-2 (AQP2) water channels and subsequent water reabsorption. AVP regulates two independent mechanisms: the short-term regulation of AQP2 trafficking and long-term regulation of the total abundance of the AQP2 protein in the cells. On the other hand, several hormones, acting through specific receptors, have been reported to antagonize AVP-mediated water transport in kidney. In this respect, we previously described that high luminal Ca²⁺ in the renal collecting duct attenuates short-term AVP-induced AQP2 trafficking through activation of the Ca²⁺-sensing receptor (CaSR). This effect is due to reduction of AVP-dependent cAMP generation and possibly hydrolysis. Moreover, CaSR signaling reduces AQP2 abundance both via AQP2-targeting miRNA-137 and the proteasomal degradation pathway. This chapter summarizes recent data elucidating the molecular mechanisms underlying the physiological role of the CaSR-dependent regulation of AQP2 expression and trafficking.

Long noncoding RNA LINC00629 restrains the progression of gastric cancer by upregulating AQP4 through competitively binding to miR-196b-5p

Gastric cancer continues to be a common cancer in the world with high incidence and mortality. Accumulating evidence has implicated long noncoding RNAs (lncRNAs) in gastric cancer progression. Here, this study identified the potential role of a novel lncRNA, LINC00629 in gastric cancer and to elucidate the underlying mechanism. Initially, microarray-based gene expression profiling of gastric cancer was employed to identify differentially expressed genes. Next, the expression of LINC00629, microRNA-196b-5p (miR-196b-5p) and aquaporin 4 (AQP4) in clinical gastric cancer tissues was determined and the cell line presenting with the lowest LINC00629 expression was selected. The interaction among LINC00629, miR-196b-5p, and AQP4 was identified. Expression of LINC00629, miR-196b-5p, and AQP4 in gastric cancer cells were altered and then biological behaviors of gastric cancer cells were assessed by 5-ethynyl-2'-deoxyuridine and Transwell assays. Tumor formation in vivo was evaluated in nude mice. In gastric cancer, expression of LINC00629 and AQP4 was downregulated, and expression of miR-196b-5p was upregulated. Proliferation, invasion, and migration of gastric cancer cells were reduced after overexpression of LINC00629. LINC00629 competitively bound to miR-196b-5p, while AQP4 was a target of miR-196b-5p. Either downregulating miR-196b-5p or upregulating AQP4 could restrain the development of gastric cancer in vitro. LINC00629 overexpression repressed the growth of transplanted tumors in vivo. Taken together, LINC00629 competitively bound to miR-196b-5p to upregulate AQP4 expression, thereby inhibiting gastric cancer progression. Therefore, understanding of this mechanism may help to improve gastric cancer treatment.

Renal Ca2+ and Water Handling in Response to Calcium Sensing Receptor Signaling: Physiopathological Aspects and Role of CaSR-Regulated microRNAs

Calcium (Ca²⁺) is a universal and vital intracellular messenger involved in a diverse range of cellular and biological processes. Changes in the concentration of extracellular Ca²⁺ can disrupt the normal cellular activities and the physiological function of these systems. The calcium sensing receptor (CaSR) is a unique G protein-coupled receptor (GPCR) activated by extracellular Ca²⁺ and by other physiological cations, aminoacids, and polyamines. CaSR is the main controller of the extracellular Ca²⁺ homeostatic system by regulating parathyroid hormone (PTH) secretion and, in turn, Ca²⁺ absorption and resorption. Recent advances highlight novel signaling pathways activated by CaSR signaling involving the regulation of microRNAs (miRNAs). miRNAs are naturally-occurring small non-coding RNAs that regulate post-transcriptional gene expression and are involved in several diseases. We previously described that high luminal Ca²⁺ in the renal collecting duct attenuates short-term vasopressin-induced aquaporin-2 (AQP2) trafficking through CaSR activation. Moreover, we demonstrated that CaSR signaling reduces AQP2 abundance via AQP2-targeting miRNA-137. This review summarizes the recent data related to CaSR-regulated miRNAs signaling pathways in the kidney.

Wall shear stress can improve prediction accuracy for transient ischemic attack

BACKGROUND

Early prediction of transient ischemic attack (TIA) has important clinical value. To date, systematic studies on clinical, biochemical, and imaging indicators related to carotid atherosclerosis have been carried out to predict the occurrence of TIA. However, their prediction accuracy is limited.

AIM

To explore the role of combining wall shear stress (WSS) with conventional predictive indicators in improving the accuracy of TIA prediction.

METHODS

A total of 250 patients with atherosclerosis who underwent carotid ultrasonography at Naval Military Medical University Affiliated Gongli Hospital were recruited. Plaque location, plaque properties, stenosis rate, peak systolic velocity, and end diastolic velocity were measured and recorded. The WSS distribution map of the proximal and distal ends of the plaque shoulder was drawn using the shear stress quantitative analysis software, and the average values of WSS were recorded. The laboratory indicators of the subjects were recorded. The patients were followed for 4 years. Patients with TIA were included in a TIA group and the remaining patients were included in a control group. The clinical data, laboratory indicators, and ultrasound characteristics of the two groups were analyzed. Survival curves were plotted by the Kaplan-Meier method. Receiver operating characteristic curves were established to evaluate the accuracy of potential indicators in predicting TIA. Logistic regression model was used to establish combined prediction, and the accuracy of combined predictive indicators for TIA was explored.

RESULTS

The intraclass correlation coefficients of the WSS between the proximal and distal ends of the plaque shoulder were 0.976 and 0.993, respectively, which indicated an excellent agreement. At the end of the follow-up, 30 patients suffered TIA (TIA group) and 204 patients did not (control group). Hypertension (P = 0.037), diabetes (P = 0.026), homocysteine (Hcy) (P = 0.022), fasting blood glucose (P = 0.034), plaque properties (P = 0.000), luminal stenosis rate (P = 0.000), and proximal end WSS (P = 0.000) were independent influencing factors for TIA during follow-up. The accuracy of each indicator for predicting TIA individually was not high (area under the curve [AUC] < 0.9). The accuracy of the combined indicator including WSS (AUC = 0.944) was significantly higher than that of the combined indicator without WSS (AUC = 0.856) in predicting TIA (z = 2.177, P = 0.030). The sensitivity and specificity of the combined indicator including WSS were 86.67% and 92.16%, respectively.

CONCLUSION

WSS at plaque surface combined with hypertension, diabetes, Hcy, blood glucose, plaque properties, and stenosis rate can significantly improve the accuracy of predicting TIA.

Astrocytes in the Pathogenesis of Multiple Sclerosis: An In Situ MicroRNA Study

Astrocytes are increasingly recognized as active contributors to the disease process in multiple sclerosis (MS), rather than being merely reactive. We investigated the expression of a selected microRNA (miRNA) panel that could contribute both to the injury and to the recovery phases of the disease. Individual astrocytes were laser microdissected from brain sections. We then compared the miRNAs’ expressions in MS and control brain samples at different lesional stages in white versus grey matter regions. In active MS lesions, we found upregulation of ischemia-related miRNAs in white but not grey matter, often with reversion to the normal state in inactive lesions. In contrast to our previous findings on MS macrophages, expression of 2 classical inflammatory-related miRNAs, miRNA-155 and miRNA-146a, was reduced in astrocytes from active and chronic active MS lesions in white and grey matter, suggesting a lesser direct pathogenetic role for these miRNAs in astrocytes. miRNAs within the categories regulating aquaporin4 (-100, -145, -320) and glutamate transport/apoptosis/neuroprotection (-124a, -181a, and -29a) showed some contrasting responses. The regional and lesion-stage differences of expression of these miRNAs indicate the remarkable ability of astrocytes to show a wide range of selective responses in the face of differing insults and phases of resolution.

Sex-specific up-regulation of lncRNAs in peripheral blood of patients with schizophrenia

Schizophrenia as a common disabling psychiatric disorder has been associated with dysregulation of several genes and pathways among them are those being regulated by long non-coding RNAs (lncRNAs). Based on the acknowledged roles of lncRNAs in neurodevelopment, in the current study, we assessed expression of six lncRNAs namely HOXA-AS2, Linc-ROR, MALAT1, MEG3, SPRY4-IT1 and UCA1 in peripheral blood of 60 patients with schizophrenia and 60 healthy subjects. HOXA-AS2, Linc-ROR, MEG3, SPRY4-IT1 and UCA1 levels were significantly higher in total patients compared with total controls. However, when evaluating expression of genes in sex-based subgroups, the differences in the expression of these lncRNAs were significant only among females. Assessment of partial correlation between expression of lncRNAs and age of study participants after controlling the effect of sex, revealed significant correlations for HOXA-AS2, MALAT1 and UCA1 in both patients and controls. Besides, expressions of Linc-ROR and SPRY4-IT1 were correlated with age only in patients. Significant pairwise correlations were recognized between expression levels of lncRNAs in both patients with schizophrenia and controls. Based on the area under curve (AUC) values, SPRY4-IT1 had the best performance in differentiation of female patients with schizophrenia from female controls (AUC = 0.85, P < 0.0001). Combination of Linc-ROR, MEG3, SPRY4-IT1 and UCA1 expression levels could differentiate female patients with 95.2% sensitivity, 76.9% specificity and diagnostic power of 0.88 (P < 0.0001). The current study suggests the presence of a sex-based dysregulation of lncRNAs in patients with schizophrenia and their possible application as diagnostic biomarkers.

Cerebrovascular miRNAs correlate with the clearance of Aβ through perivascular route in younger 3xTg-AD mice

The "two-hit vascular hypothesis for Alzheimer's disease (AD)" and amyloid-β (Aβ) oligomer hypothesis suggest that impaired soluble Aβ oligomers clearance through the cerebral vasculature may be an initial step of the AD process. Soluble Aβ oligomers are driven into perivascular spaces from the brain parenchyma and toward peripheral blood flow. The underlying vascular-based mechanism, however, has not been defined. Given that microRNAs (miRNAs), emerging as novel modulators, are involved in numerous physiological and pathological processes, we hypothesized that cerebrovascular miRNAs may regulate the activities of brain blood vessels, which further affects the concentration of Aβ in the AD brain. In this study, perivascular Aβ deposits, higher vascular activation, increased pericyte coverage and up-regulated capillaries miRNAs at 6 months old (6 mo) were found to correlate with the lower Aβ levels of middle AD stage (9 mo) in 3xTg-AD (3xTg) mice. It is implicated that at the early stage of AD when intracellular Aβ appeared, higher expression of vessel-specific miRNAs, elevated pericyte coverage, and activated endothelium facilitate Aβ oligomer clearance through the perivascular route, resulting in a transient reduction of Aβ oligomers at 9 mo. Additionally, ghrelin-induced upregulation of capillary miRNAs and increased pericyte coverage attenuated Aβ burden at 9 mo, in further support of the relationship between vascular miRNAs and Aβ clearance. This work suggests a cerebral microvessel miRNA may boost endothelial highly activated phenotypes to promote elimination of Aβ oligomers through the perivascular drainage pathway and contribute to AD progression. The targeting of brain vessel-specific miRNAs may provide a new rationale for the development of innovative therapeutic strategies for AD treatment.

A Genome-Wide Analysis of the Penumbral Volume in Inbred Mice following Middle Cerebral Artery Occlusion

Following ischemic stroke, the penumbra, at-risk neural tissue surrounding the core infarct, survives for a variable period of time before progressing to infarction. We investigated genetic determinants of the size of penumbra in mice subjected to middle cerebral artery occlusion (MCAO) using a genome-wide approach. 449 male mice from 33 inbred strains underwent MCAO for 6 hours (215 mice) or 24 hours (234 mice). A genome-wide association study using genetic data from the Mouse HapMap project was performed to examine the effects of genetic variants on the penumbra ratio, defined as the ratio of the infarct volume after 6 hours to the infarct volume after 24 hours of MCAO. Efficient mixed model analysis was used to account for strain interrelatedness. Penumbra ratio differed significantly by strain (F = 2.7, P < 0.001) and was associated with 18 significant SNPs, including 6 protein coding genes. We have identified 6 candidate genes for penumbra ratio: Clint1, Nbea, Smtnl2, Rin3, Dclk1, and Slc24a4.

Mesenchymal Stem Cell-Derived Extracellular Vesicle Therapy for Stroke: Challenges and Progress

Stroke is the leading cause of physical disability among adults. Stem cells such as mesenchymal stem cells (MSCs) secrete a variety of bioactive substances, including trophic factors and extracellular vesicles (EVs), into the injured brain, which may be associated with enhanced neurogenesis, angiogenesis, and neuroprotection. EVs are circular membrane fragments (30 nm−1 μm) that are shed from the cell surface and harbor proteins, microRNAs, etc. Since 2013 when it was first reported that intravenous application of MSC-derived EVs in a stroke rat model improved neurological outcomes and increased angiogenesis and neurogenesis, many preclinical studies have shown that stem cell-derived EVs can be used in stroke therapy, as an alternative approach to stem cell infusion. Although scientific research regarding MSC-derived EV therapeutics is still at an early stage, research is rapidly increasing and is demonstrating a promising approach for patients with severe stroke. MSC therapies have already been tested in preclinical studies and clinical trials, and EV-mediated therapy has unique advantages over cell therapies in stroke patients, in terms of biodistribution (overcoming the first pass effect and crossing the blood-brain-barrier), cell-free paradigm (avoidance of cell-related problems such as tumor formation and infarcts caused by vascular occlusion), whilst offering an off-the-shelf approach for acute ischemic stroke. Recently, advances have been made in the understanding of the function and biogenesis of EVs and EVs therapeutics for various diseases. This review presents the most recent advances in MSC-derived EV therapy for stroke, focusing on the application of this strategy for stroke patients.

miR‑29a ameliorates ischemic injury of astrocytes in vitro by targeting the water channel protein aquaporin 4

Ischemic stroke is the main cause of brain injury and results in a high rate of morbidity, disability and mortality. In the present study, we aimed to determine whether miR-29a played a protective role in oxygen glucose deprivation (OGD) injury via regulation of the water channel protein aquaporin 4 (AQP4). Real-time PCR and western blotting were used to assess miR-29a levels and AQP4 protein levels, respectively. Apoptosis was detected by flow cytometry, and lactate dehydrogenase (LDH) was determined by enzyme-linked immunosorbent assay (ELISA). Overexpression of miR-29a was significantly downregulated in OGD-induced primary astrocytes, and transfection with a miR-29a mimic decreased LDH release and apoptosis, and improved cell health in OGD-induced astrocytes. AQP4 was the target of miR-29a, which suppressed AQP4 expression, and knockdown of AQP4 mitigated OGD-induced astrocyte injury. Furthermore, miR-29a regulated AQP4 expression in OGD-induced astrocytes. AQP4 exacerbated astrocyte injury following ischemic stroke, and knockdown of AQP4 protected OGD/RX-induced primary cultured astrocytes against injury. The effect of miR-29a inhibitor on primary astrocytes was lost following AQP4 knockdown. These findings indicated that miR-29a prevented astrocyte injury in vitro by inhibiting AQP4. Thus, miR-29a may protect primary cultured astrocytes after OGD-induced injury by targeting AQP4, and may be a potential therapeutic target for ischemic injury of astrocytes.

miR-145 protects the function of neuronal stem cells through targeting MAPK pathway in the treatment of cerebral ischemic stroke rat

This study is designed to investigate the function of the miR-145 in the protection of neural stem cells (NSCs) through targeting mitogen-activated protein kinase (MAPK) pathway in the treatment of cerebral ischemic stroke rat. In our study, rat NSCs were selected and cultured in complete medium. The light microscopy was used to observe the morphology of NSCs at different times. The quantitative reverse transcriptase real-time polymerase chain reaction (qRT-PCR) was used to detect the miR-145 and other related mRNAs of the MARK pathway. The Western blotting was used to detect the activation of MAPK pathway and neuronal specific markers. The Immunofluorescence was used to detect the expression of the neuron-specific enolase. And the cell viability was detected by Cell Counting Kit (CCK)-8 assay. The flow cytometry was used to test the cell cycle and apoptosis. The ischemic stroke rat models were established and neural stem cell transplantation was performed. The neurological function score, balance beam experiment, and cortical Nissl staining were used to evaluate the postoperative neurological function in rats. The expression of miR-145, extracellular signal-regulated kinase (ERK), and p38 mRNA in rat NSCs increased in a time-dependent manner. Compared with the Blank group, the over-expression of miR-145 promoted the expression of related mRNA and protein of the MAPK pathway in NSCs, while the decreased expression of miR-145 suppressed the MAPK Pathways. Compared with the Blank group, over-expression of miR-145 in NSCs promoted the up-regulation of Cyclin D1, Nestin, neuron-specific enolase (NSE), and Glial fibrillary acidic protein (GFAP) proteins, enhanced the activity of NSCs, and promoted cell proliferation and differentiation, while inhibited the cell apoptosis and the Cleaved-caspase 3 expression. After treatment of NSCs in the SB203580 group, the Nestin, NSE, and GFAP were decreased; cell viability, proliferation and differentiation were inhibited, while Cleaved-caspase 3 protein and cell apoptosis rate increased. The results of animal experiments showed that compared with the Blank group, the walking ability and neurological impairment recovered rapidly in the rats after transplantation of NSCs with over-expression of miR-145, and more neurons were generated in the cortex. After the transplantation of SB203580-treated NSCs, the walking ability and neurological impairment of the rats were slower and the cortical neurons were less. We conclude that miR-145 protects the function of neuronal stem cells through targeting MAPK pathway in the treatment of cerebral ischemic stroke rat.

The Emerging Role of microRNAs in Aquaporin Regulation

Aquaporins (AQPs) are membrane channels widely distributed in human tissues. AQPs are essential for water and energy homeostasis being involved in a broad range of pathophysiological processes such as edema, brain injury, glaucoma, nephrogenic diabetes insipidus, salivary and lacrimal gland dysfunction, cancer, obesity and related metabolic complications. Compelling evidence indicates that AQPs are targets for therapeutic intervention with potential broad application. Nevertheless, efficient AQP modulators have been difficult to find due to either lack of selectivity and stability, or associated toxicity that hamper in vivo studies. MicroRNAs (miRNAs) are naturally occurring small non-coding RNAs that regulate post-transcriptional gene expression and are involved in several diseases. Recent identification of miRNAs as endogenous modulators of AQP expression provides an alternative approach to target these proteins and opens new perspectives for therapeutic applications. This mini-review compiles the current knowledge of miRNA interaction with AQPs highlighting miRNA potential for regulation of AQP-based disorders.