MiRNAs: potential diagnostic and therapeutic targets for cerebral ischaemia

The role of microRNA in neuronal inflammation and survival in the post ischemic brain: a review

Each year, more than 790 000 people in the United States suffer from a stroke. Although progress has been made in diagnosis and treatment of ischemic stroke (IS), new therapeutic interventions to protect the brain during an ischemic insult is highly needed. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression post-transcriptionally. Growing evidence suggests that miRNAs have a profound impact on ischemic stroke progression and are potential targets of novel treatments. Notably, inflammatory pathways play an important role in the pathogenesis of ischemic stroke and its pathophysiologic progression. Experimental and clinical studies have illustrated that inflammatory molecular events collaboratively contribute to neuronal and glial cell survival, edema formation and regression, and vascular integrity. In the present review, we examine recent discoveries regarding miRNAs and their roles in post-ischemic stroke neuropathogenesis.

Influence of the rs6736 Polymorphism on Ischemic Stroke Susceptibility in Han Chinese Individuals via the Disruption of miR-7-1 Binding to the C14orf119 Gene

This study investigates the association between the C14orf119 gene rs6736 polymorphism and ischemic stroke (IS) susceptibility, and explores the influence of the rs6736 polymorphism on the binding between miR-7-1 and the C14orf119 gene. mRNA expression levels were determined in 45 IS patients and 45 matched controls via real-time quantitative PCR. A total of 774 IS patients and 793 matched controls were recruited from a Han Chinese population for genotyping, performed with the Sequenom MassARRAY iPLEX platform. A dual-luciferase reporter assay was used for the analysis of miRNA-mRNA binding. The results showed that the mRNA expression of C14orf119 differed significantly between IS patients and controls (t =  -2.235, P = 0.030). Significant associations were noted between the C14orf119 gene rs6736 polymorphism and IS susceptibility in Han Chinese individuals under the additive model [OR_adj (95% CI) = 0.87 (0.76-1.00) P_adj = 0.048] and dominant model [OR_adj (95% CI) = 0.76 (0.61-0.94), P_adj = 0.014], with adjustment for age and sex. Mutations in the rs6736 polymorphism disrupted the binding of miR-7-1 and the C14orf119 gene. The results of this study show that the rs6736 polymorphism in the 3'-untranslated region of the C14orf119 gene not only is associated with IS but also modifies the binding between miR-7-1 and the C14orf119 gene. The C14orf119 gene may participate in the relationship between IS and miR-7-1.

Extracellular vesicles derived from M2 microglia reduce ischemic brain injury through microRNA-135a-5p/TXNIP/NLRP3 axis

Accumulating evidences have suggested that extracellular vesicles (EVs) are crucial players in the pathogenesis of ischemic brain injury. This study was designed to explore the specific functions of M2 phenotype microglia-derived EVs in ischemic brain injury progression. The expression of microRNA-135a-5p (miR-135a-5p) in M2 microglia-derived EVs was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), followed by the identification of expression relationship among miR-135a-5p, thioredoxin-interacting protein (TXNIP), and nod-like receptor protein 3 (NLRP3) by dual luciferase reporter gene assay. After construction of an oxygen-glucose deprivation/reperfusion (OGD/R) cell model, the effects of miR-135a-5p on the biological characteristics of HT-22 cells were assessed by cell counting kit 8 (CCK-8) assay and flow cytometry. Finally, a mouse model of transient middle cerebral artery occlusion (tMCAO) was established and cerebral infarction volume was determined by triphenyltetrazolium chloride (TTC) staining and the expression of IL-18 and IL-1β in the brain tissue was determined by enzyme-linked immunosorbent assay (ELISA). We found that M2 microglia-derived EVs had high expression of miR-135a-5p, and that miR-135a-5p in M2 microglia-derived EVs negatively regulated the expression of NLRP3 via TXNIP. Overexpression of miR-135a-5p promoted the proliferation but inhibited the apoptosis of neuronal cells, and inhibited the expression of autophagy-related proteins. M2 microglia-derived EVs delivered miR-135a-5p into neuronal cells to inhibit TXNIP expression, which further inhibited the activation of NLRP3 inflammasome, thereby reducing neuronal autophagy and ischemic brain injury. Hence, M2 microglia-derived EVs are novel therapeutic targets for ischemic brain injury treatment.

Typhae pollen polysaccharides protect hypoxia-induced PC12 cell injury via regulation of miR-34a/SIRT1

This current research was performed to investigate the role of typhae pollen polysaccharides (TPP) in hypoxia-treated PC12 cell which was an in vitro cell model of cerebral ischemia. Hypoxia-treated cells were treated with TPP for 12 h. Cell viability and apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2 5-diphenyl-2H-tetrazolium bromide (MTT) assay and flow cytometry, respectively. Cell apoptotic proteins and PI3K/AKT and Ras/Raf/MEK/ERK signal pathway–associated proteins were also examined by western blot. Furthermore, abnormal expression of miR-34a and silent information regulator 1 (SIRT1) was achieved by transfection. Besides, the expression of miR-34a and SIRT1 was examined by quantitative real-time polymerase chain reaction (qRT-PCR). The expression of SIRT1 was detected by qRT-PCR and western blot. The relationship between miR-34a and SIRT1 was verified by luciferase assay. We found that TPP enhanced cell viability and inhibited apoptosis in hypoxia-treated PC12 cells. Moreover, TPP increased the accumulated levels of Bcl-2 while decreased expression of Bax, cleaved Caspase-3, and cleaved PARP. TPP downregulated miR-34a expression while induced by hypoxia. Further results showed that miR-34a overexpression reversed the results led by TPP in cell viability, apoptosis, and its related proteins. In addition, SIRT1 was upregulated by TPP and was verified to be a target of miR-34a. Silence of SIRT1 led to the opposite results led by TPP. In the end, TPP activated PI3K/AKT and Ras/Raf/MEK/ERK signal pathways. In conclusion, TPP plays important roles in regulating cell viability and apoptosis in hypoxia-treated PC12 cells via modulating miR-34a/SIRT1, as well as activating PI3K/AKT and Ras/Raf/MEK/ERK signal pathways.

MicroRNA-342-5p activates the Akt signaling pathway by downregulating PIK3R1 to modify the proliferation and differentiation of vascular smooth muscle cells

Abnormal cell proliferation and invasion of vascular smooth muscle cells are among the primary causes of cardiovascular disease. Studies have shown that microRNA(miR)-342-5p participates in the development of cardiovascular diseases. The current study aimed to explore the role of miR-342-5p in the proliferation and differentiation of mouse aortic vascular smooth muscle (MOVAS) cells. MOVAS cells were transfected with miR-342-5p mimics, miR-342-5p inhibitor or their respective negative controls, and co-transfected with small interfering (si)RNA targeting phosphatidylinositol 3-kinase regulatory subunit α (PIK3R1) and miR-342-5p inhibitor. The cell proliferation of MOVAS cells was detected using the Cell Counting Kit-8, while cell migration and cell invasion were investigated using a wound healing and Transwell assays, respectively. Target genes for miR-342-5p were confirmed using reverse transcription-quantitative PCR (RT-qPCR) and dual luciferase reporter assay. The relative mRNA and protein expression levels of miR-342-5p were measured using RT-qPCR and western blot analysis. MOVAS cells were treated with a PI3K inhibitor (LY294002) to explore the role of miR-342-5p on the Akt pathway. The results revealed that miR-342-5p mimics promoted cell viability, migration and invasion, and increased the expression of vimentin and phosphorylated-Akt but reduced a-smooth muscle actin (α-SMA) and PIK3R1 expression. However, miR-342-5p inhibitor produced the opposite effects. PIK3R1 was the target gene for miR-342-5p and the effect of siPIK3R1 on MOVAS cells was similar to that of miR-342-5p mimics, while siPIK3R1 partially reversed the effect of miR-342-5p inhibitor on MOVAS cells. The Akt signaling pathway was activated by miR-342-5p mimics or siPIK3R1. Moreover, miR-342-5p mimics partially activated the Akt signaling pathway inhibited by LY294002. MiR-342-5p could promote the proliferation and differentiation of MOVAS and phenotypic transformation. The mechanism behind these processes may be associated with the activation of the Akt signaling pathway induced by PIK3R1 inhibition.

Inhibition of microRNA-148b-3p alleviates oxygen-glucose deprivation/reoxygenation-induced apoptosis and oxidative stress in HT22 hippocampal neuron via reinforcing Sestrin2/Nrf2 signalling

MicroRNAs (miRNAs) have emerged as crucial regulators of neuronal injury during cerebral ischaemia/reperfusion injury. Various miRNAs are dysregulated during this pathological process; however, the precise role of these miRNAs in regulating neuronal injury remains largely unknown. In the current study, we explored the potential function of microRNA-148b-3p (miR-148b-3p) in regulating neuronal injury induced by oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro, a cellular model for mimicking cerebral ischaemia/reperfusion injury. We found that miR-148b-3p expression was significantly decreased in neurons in response to OGD/R exposure. Importantly, miR-148b-3p overexpression decreased cell viability and exacerbated apoptosis and reactive oxygen species (ROS) production in OGD/R-exposed neurons. By contrast, miR-148b-3p inhibition improved cell viability and decreased apoptosis and ROS production in OGD/R-exposed neurons. Notably, Sestrin2, a cytoprotective gene, was identified as a miR-148b-3p target gene. miR-148b-3p inhibition markedly increased Sestrin2 expression as well as the activation of nuclear factor erythroid-2-related factor 2 (Nrf2) antioxidant signalling. Moreover, silencing of Sestrin2 or Nrf2 significantly reversed the miR-148-3p-inhibition-mediated protective effect in OGD/R-injured neurons. Overall, these results demonstrate that miR-148b-3p inhibition protects neurons from OGD/R-induced apoptosis and ROS production through reinforcing Nrf2 antioxidant signalling via upregulation of Sestrin2. Our study indicates that the miR-148b-3p/Sestrin2/Nrf2 axis plays an important role in regulating neuronal injury and may serve as a potential therapeutic target for providing neuroprotection during cerebral ischaemia/reperfusion injury.

Sevoflurane prevents miR-181a-induced cerebral ischemia/reperfusion injury

BACKGROUND

Sevoflurane (sevo) has been reported to be an effective neuroprotective agent in cerebral ischemia/reperfusion injury (CIRI). However, the precise molecular mechanism underlying sevo preconditioning in CIRI remains largely unknown.

METHODS

A middle cerebral artery occlusion (MCAO) rat model and primary cortical neurons after oxygen-glucose deprivation and reoxygenation (OGDR) were used as the in vivo and in vitro models of CIRI. The expression profiles of miR-181a and X chromosome-linked inhibitor-of-apoptosis protein (XIAP) in the cerebral cortex of rats and in cortical neurons were examined by qRT-PCR and Western blot, respectively. The infarct volumes were measured by TTC staining and neurological deficits in rats was determined by Zea-Longa scoring criteria. The cell viability, lactate dehydrogenase (LDH) release and apoptotic rate were detected in cortical neurons by MTT assay, LDH analysis and flow cytometry. Western blot analysis was performed to assess the expression of apoptosis-related protein. Luciferase reporter assay was used to confirm the interaction between miR-181a and XIAP.

RESULTS

miR-181a was upregulated and XIAP was downregulated in rats after MCAO. Sevo preconditioning attenuated miR-181a expression and promoted XIAP level in a rat model of CIRI. Sevo preconditioning ameliorated anti-miR-181a-mediated protective effects on cerebral ischemia in rat model of CIRI, presented as the decrease of infarct volume, neurological deficit and apoptosis. Moreover, sevo pretreatment abated miR-181a-induced cellular injury in primary cortical neurons after OGD, embodied by the increase of cell viability, the reduction of LDH release and the decline of apoptosis. Furthermore, miR-181a suppressed XIAP expression by binding to its 3'UTR in cortical neurons, and sevo-mediated increase on XIAP expression was counteracted by miR-181 overexpression in OGDR-treated neurons.

CONCLUSION

Sevo preconditioning protected against CIRI in vitro and in vivo possibly by inhibiting miR-181a and facilitating XIAP.

The MicroRNA Family Both in Normal Development and in Different Diseases: The miR-17-92 Cluster

An increasing number of research studies over recent years have focused on the function of microRNA (miRNA) molecules which have unique characteristics in terms of structure and function. They represent a class of endogenous noncoding single-strand small molecules. An abundance of miRNA clusters has been found in the genomes of various organisms often located in a polycistron. The miR-17-92 family is among the most famous miRNAs and has been identified as an oncogene. The functions of this cluster, together with the seven individual molecules that it comprises, are most related to cancers, so it would not be surprising that they are considered to have involvement in the development of tumors. The miR-17-92 cluster is therefore expected not only to be a tumor marker, but also to perform an important role in the early diagnosis of those diseases and possibly also be a target for tumor biotherapy. The miR-17-92 cluster affects the development of disease by regulating many related cellular processes and multiple target genes. Interestingly, it also has important roles that cannot be ignored in disease of the nervous system and circulation and modulates the growth and development of bone. Therefore, it provides new opportunities for disease prevention, clinical diagnosis, prognosis, and targeted therapy. Here we review the role of the miR-17-92 cluster that has received little attention in relation to neurological diseases, cardiac diseases, and the development of bone and tumors.

Association of MicroRNA-146a and MicroRNA-149 Polymorphisms With Strokes in Asian Populations: An Updated Meta-Analysis

Strokes are a major cause of disability and death worldwide. An association between microRNA-146a (miR-146a) and miR-149 polymorphisms and strokes was inconclusive. This meta-analysis aimed to reevaluate the strength of the association by searching online databases and retrieving relevant case-control studies published between 2000 and 2016. Nine articles including 8 on miR-146a rs2910164 G/C and 3 on miR-149 rs2292832 C/T in 3372 patients with stroke and 4394 controls were included. The miR-149 rs2292832 was significantly associated with the risk of a stroke under allelic (C vs T: odds ratio [OR] = 1.14; 95% confidence interval [CI] = 1.01-1.29; P = .03), homologous (CC vs TT: OR = 1.36; 95% CI = 1.05-1.77; P = .02), and recessive models (CC vs CT + TT: OR = 1.34; 95% CI = 1.05-1.71; P = .02). No correlation was detected between miR-146a rs2910164 and susceptibility to a stroke. In conclusion, the results suggested that miR-149 might be a risk factor for the development of a stroke, while miR-146a might not be. Well-designed studies with large populations are needed to clarify the association between miR-146a and miR-149 polymorphisms and strokes.

Pigmy MicroRNA: surveillance cops in Therapies kingdom

MicroRNAs (miRNAs) are well preserved in every animal. These pigmy sized non-coding RNAs (21-23 nt), scattered in genome, are responsible for micromanaging the versatile gene regulations. Involvement of miRNAs was surveillance cops in all human diseases including cardiovascular defects, tumor formation, reproductive pathways, and neurological and autoimmune disorders. The effective functional role of miRNA can be reduced by chemical entities of antisense oligonucleotides and versatile small molecules that support the views of novel therapy of different human diseases. In this study, we have updated our current understanding for designing and synthesizing miRNA-controlling therapeutic chemicals. We have also proposed various in-vivo delivery strategies and their ongoing challenges to combat the incorporation hurdles in live cells and animals. Lastly, we have demonstrated the current progress of miRNA modulation in the treatment of different human diseases that provides an alternative approach of gene therapy.