Analysis of microRNA Expression Detected by Microarray of the Cerebral Cortex After Hypoxic-Ischemic Brain Injury

Hypoxic-Ischemic Brain Injury in ECMO: Pathophysiology, Neuromonitoring, and Therapeutic Opportunities

Extracorporeal membrane oxygenation (ECMO), in conjunction with its life-saving benefits, carries a significant risk of acute brain injury (ABI). Hypoxic-ischemic brain injury (HIBI) is one of the most common types of ABI in ECMO patients. Various risk factors, such as history of hypertension, high day 1 lactate level, low pH, cannulation technique, large peri-cannulation PaCO2 drop (∆PaCO2), and early low pulse pressure, have been associated with the development of HIBI in ECMO patients. The pathogenic mechanisms of HIBI in ECMO are complex and multifactorial, attributing to the underlying pathology requiring initiation of ECMO and the risk of HIBI associated with ECMO itself. HIBI is likely to occur in the peri-cannulation or peri-decannulation time secondary to underlying refractory cardiopulmonary failure before or after ECMO. Current therapeutics target pathological mechanisms, cerebral hypoxia and ischemia, by employing targeted temperature management in the case of extracorporeal cardiopulmonary resuscitation (eCPR), and optimizing cerebral O2 saturations and cerebral perfusion. This review describes the pathophysiology, neuromonitoring, and therapeutic techniques to improve neurological outcomes in ECMO patients in order to prevent and minimize the morbidity of HIBI. Further studies aimed at standardizing the most relevant neuromonitoring techniques, optimizing cerebral perfusion, and minimizing the severity of HIBI once it occurs will improve long-term neurological outcomes in ECMO patients.

Role of miR-182 in cardiovascular and cerebrovascular diseases

The treatment of cardiovascular and cerebrovascular diseases have undergone major advances in recent decades, allowing for a more effective prevention of cardiovascular and cerebrovascular events. However, cardiac and cerebral atherothrombotic complications still account for substantial morbidity and mortality worldwide. Novel therapeutic strategies are critical to improve patient outcomes following cardiovascular diseases. miRNAs are small non-coding RNAs, that regulate gene expression. Here, we discuss the role of miR-182 in regulating myocardial proliferation, migration, hypoxia, ischemia, apoptosis and hypertrophy in atherosclerosis, CAD, MI, I/R injury, organ transplant, cardiac hypertrophy, hypertension, heart failure, congenital heart disease and cardiotoxicity. Besides, we also summarize the current progress of miR-182 therapeutics in clinical development and discuss challenges that will need to be overcome to enter the clinic for patients with cardiac disease.

miR-200b-3p antagomir inhibits neuronal apoptosis in oxygen-glucose deprivation (OGD) model through regulating β-TrCP

BACKGROUND

Hypoxia-ischemic brain damage (HIBD) is a primary cause of morbidity and disability in survivors of preterm infants. We previously discovered that miR-200b-3p plays an important role in HIBD via targeting Slit2. This study was designed to identify novel targets of miR-200b-3p and investigate the relationship between miR-200b-3p and its downstream effectors.

METHODS AND RESULTS

Cultured primary rat hippocampal neurons were used in the model of oxygen-glucose deprivation (OGD) and RT-qPCR was utilized to detect the alterations of miR-200b-3p in these cells following the OGD. Our study found that the expression of miR-200b-3p was up-regulated in neurons post OGD. Bioinformatics analysis identified that β transducin repeat-containing protein (β-TrCP) is a target gene of miR-200b-3p, and our luciferase reporter gene assay confirmed that miR-200b-3p can interact with β-TrCP mRNA. Hypoxia-ischemic brain damage was induced in three-day-old SD rats and inhibition of miR-200b-3p by injection of antagomir into bilateral lateral ventricles enhanced β-TrCP expression at both the mRNA and protein levels in rats' brains. TUNEL staining and CCK-8 assays found that the survival of hippocampal neurons in the miR-200b-3p antagomir group was improved significantly (p＜0.05), whereas apoptosis of neurons in the miR-200b-3p antagomir group was significantly decreased (p＜0.05), as compared with the OGD group. However, silencing of β-TrCP by β-TrCP siRNA impaired the neuroprotective effect of miR-200b-3p antagomir. H&E staining showed that miR-200b-3p attenuated the pathological changes in the hippocampal region of rats with HIBD.

CONCLUSION

Our study has demonstrated that β-TrCP is a target gene of miR-200b-3p and that inhibition of miR-200b-3p by antagomir attenuates hypoxia-ischemic brain damage via β-TrCP.

microRNA-93 packaged in extracellular vesicles from mesenchymal stem cells reduce neonatal hypoxic-ischemic brain injury

OBJECTIVE

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have been proposed as a promising strategy for treating ischemia-related diseases. Herein, we probed into the role of miR-93 delivered by BMSC-EVs in hypoxic-ischemic brain injury (HIBD).

METHODS

Neonatal HIBD mouse models and hippocampal neuron models of oxygen glucose deprivation (OGD) were constructed. EVs were isolated from the culture medium of bone marrow MSCs (BMSCs). After co-culture of BMSC-EVs with OGD-exposed hippocampal neurons, the effect of microRNA-93 (miR-93) delivered by BMSC-EVs on OGD-induced hippocampal neurons as well as on HIBD in vivo under transfection of miR-93 mimic or inhibitor was explored. The interaction among miR-93, JMJD3, and p53/KLF2 axis was assessed.

RESULTS

BMSC-EVs prevented OGD-induced hippocampal neuron apoptosis and inflammation, which was associated with their transfer of miR-93 into the hippocampal neurons. miR-93 targeted JMJD3 and downregulated its expression, thus inhibiting the OGD-induced hippocampal neuron apoptosis. By regulating the JMJD3/p53/KLF2 axis, miR-93 in BMSC-EVs reduced the OGD-induced hippocampal neuron apoptosis in vitro as well as alleviating HIBD in vivo.

CONCLUSIONS

The current study highlighted that miR-93 delivered by BMSC-EVs alleviated HIBD in neonatal mice through the JMJD3-dependent p53/KLF2 axis.

Hearing impairment due to Mir183/96/182 mutations suggests both loss and gain of function effects

The microRNA miR-96 is important for hearing, as point mutations in humans and mice result in dominant progressive hearing loss. Mir96 is expressed in sensory cells along with Mir182 and Mir183, but the roles of these closely-linked microRNAs are as yet unknown. Here we analyse mice carrying null alleles of Mir182, and of Mir183 and Mir96 together to investigate their roles in hearing. We found that Mir183/96 heterozygous mice had normal hearing and homozygotes were completely deaf with abnormal hair cell stereocilia bundles and reduced numbers of inner hair cell synapses at four weeks old. Mir182 knockout mice developed normal hearing then exhibited progressive hearing loss. Our transcriptional analyses revealed significant changes in a range of other genes, but surprisingly there were fewer genes with altered expression in the organ of Corti of Mir183/96 null mice compared with our previous findings in Mir96 Dmdo mutants, which have a point mutation in the miR-96 seed region. This suggests the more severe phenotype of Mir96 Dmdo mutants compared with Mir183/96 mutants, including progressive hearing loss in Mir96 Dmdo heterozygotes, is likely to be mediated by the gain of novel target genes in addition to the loss of its normal targets. We propose three mechanisms of action of mutant miRNAs; loss of targets that are normally completely repressed, loss of targets whose transcription is normally buffered by the miRNA, and gain of novel targets. Any of these mechanisms could lead to a partial loss of a robust cellular identity and consequent dysfunction.

Lessons learned from proteome analysis of perinatal neurovascular pathologies

INTRODUCTION

Perinatal and pediatric diseases related to neurovascular disorders cause significant problems during life, affecting a population with a long life expectancy. Early diagnosis and assessment of the severity of these diseases are crucial to establish an appropriate neuroprotective treatment. Currently, physical examination, neuroimaging and clinical judgment are the main tools for diagnosis, although these tests have certain limitations. There is growing interest in the potential value of noninvasive biomarkers that can be used to monitor child patients at risk of brain damage, allowing accurate, and reproducible measurements.

AREAS COVERED

This review describes potential biomarkers for the diagnosis of perinatal neurovascular diseases and discusses the possibilities they open for the classification and treatment of neonatal neurovascular diseases.

EXPERT OPINION

Although high rates of ischemic and hemorrhagic stroke exist in pediatric populations, most studies have focused on biomarkers of hypoxic-ischemic encephalopathy. Inflammatory and neuronal biomarkers such as S-100B and GFAP, in combination with others yet to be discovered, could be considered as part of multiplex panels to diagnose these diseases and potentially for monitoring response to treatments. Ideally, noninvasive biofluids would be the best source for evaluating these biomarkers in proteomic assays in perinatal patients.

Deregulated miR-384 serves as a biomarker in neonatal hypoxic-ischemic encephalopathy and alleviates microglia-mediated neuroinflammation

Microglia-mediated neuroinflammation is important in the pathogenesis of neonatal hypoxic-ischemic encephalopathy (HIE). This study aimed to investigate the expression of microRNA-384 (miR-384) in HIE newborns and evaluate the clinical and functional role of miR-384 in HIE diagnosis and neuroinflammation. The expression of miR-384 was estimated using quantitative real-time PCR. The levels of proinflammatory cytokines were examined using ELISA. Receiver operating characteristic (ROC) analysis was applied to evaluate the diagnostic performance of miR-384. The oxygen-glucose deprivation (OGD) experiment was adopted to activate primary neonatal microglia. A putative target of miR-384 was analyzed by bioinformatics prediction and a luciferase reporter assay. The expression of miR-384 was decreased in the serum of HIE newborns and OGD-induced activated microglia. Serum miR-384 had relatively high diagnostic accuracy for the screening of HIE cases from healthy newborns and the differentiation between newborns with different HIE severities. The OGD-induced increase in microglial neuroinflammation was significantly attenuated by the overexpression of miR-384, and AKT3, as a downstream target of miR-384, was inhibited by miR-384 in activated microglia. The data of this study demonstrated that decreased serum miR-384 expression may be a novel noninvasive biomarker for the diagnosis and progression of neonatal HIE. miR-384 can inhibit the neuroinflammation in activated microglia, which may be mediated by targeting AKT3.

Clinical Implications of Epigenetic Dysregulation in Perinatal Hypoxic-Ischemic Brain Damage

Placental and fetal hypoxia caused by perinatal hypoxic-ischemic events are major causes of stillbirth, neonatal morbidity, and long-term neurological sequelae among surviving neonates. Brain hypoxia and associated pathological processes such as excitotoxicity, apoptosis, necrosis, and inflammation, are associated with lasting disruptions in epigenetic control of gene expression contributing to neurological dysfunction. Recent studies have pointed to DNA (de)methylation, histone modifications, and non-coding RNAs as crucial components of hypoxic-ischemic encephalopathy (HIE). The understanding of epigenetic dysregulation in HIE is essential in the development of new clinical interventions for perinatal HIE. Here, we summarize our current understanding of epigenetic mechanisms underlying the molecular pathology of HI brain damage and its clinical implications in terms of new diagnostic, prognostic, and therapeutic tools.

MicroRNA-9 mediated the protective effect of ferulic acid on hypoxic-ischemic brain damage in neonatal rats

Neonatal hypoxic-ischemic brain damage (HIBD) is prone to cognitive and memory impairments, and there is no effective clinical treatment until now. Ferulic acid (FA) is found within members of the genus Angelica, reportedly shows protective effects on neuronal damage. However, the protective effects of FA on HIBD remains unclear. In this study, using the Morris water maze task, we herein found that the impairment of spatial memory formation in adult rats exposed to HIBD was significantly reversed by FA treatment and the administration of LNA-miR-9. The expression of miRNA-9 was detected by RT-PCR analyses, and the results shown that miRNA-9 was significantly increased in the hippocampus of neonatal rats following HIBD and in the PC12 cells following hypoxic-ischemic injury, while FA and LNA-miR-9 both inhibited the expression of miRNA-9, suggesting that the therapeutic effect of FA was mainly attributed to the inhibition of miRNA-9 expression. Indeed, the silencing of miR-9 by LNA-miR-9 or FA similarly attenuated neuronal damage and cerebral atrophy in the rat hippocampus after HIBD, which was consistent with the restored expression levels of brain-derived neurotrophic factor (BDNF). Therefore, our findings indicate that FA treatment may protect against neuronal death through the inhibition of miRNA-9 induction in the rat hippocampus following hypoxic-ischemic damage.

Circular RNA expression alteration in whole blood of premature infants with periventricular white matter damage

Circular RNAs (circRNAs) are evolutionarily conserved and tissue-specific types of non-coding RNA and can serve as potential diagnostic biomarkers for disease. However, the clinical significance and levels of expression of circRNAs for whole blood samples of prematurely born infants afflicted by diseases such as periventricular white matter damage (PWMD) are largely unknown. Therefore, we sought to identify measures of expression of circRNAs in whole blood samples obtained from prematurely born infants afflicted by PWMD and comparatively in samples from prematurely born infants without PWMD. We found the expression levels of circRNAs which from premature with PWMD has changed. Further analysis suggests that these circRNAs have important roles in PWMD. This study can improve the understanding for the potential of the circRNAs to serve as biomarkers in PWMD. Moreover, these circRNAs may provide evidence for improving diagnosis and treatment for infants afflicted by PWMD, and merits continued research.

Bone mesenchymal stem cell-derived exosomal microRNA-29b-3p prevents hypoxic-ischemic injury in rat brain by activating the PTEN-mediated Akt signaling pathway

BACKGROUND

Mesenchymal stem cells (MSCs) are suspected to exert neuroprotective effects in brain injury, in part through the secretion of extracellular vesicles like exosomes containing bioactive compounds. We now investigate the mechanism by which bone marrow MSCs (BMSCs)-derived exosomes harboring the small non-coding RNA miR-29b-3p protect against hypoxic-ischemic brain injury in rats.

METHODS

We established a rat model of middle cerebral artery occlusion (MCAO) and primary cortical neuron or brain microvascular endothelial cell (BMEC) models of oxygen and glucose deprivation (OGD). Exosomes were isolated from the culture medium of BMSCs. We treated the MCAO rats with BMSC-derived exosomes in vivo, and likewise the OGD-treated neurons and BMECs in vitro. We then measured apoptosis- and angiogenesis-related features using TUNEL and CD31 immunohistochemical staining and in vitro Matrigel angiogenesis assays.

RESULTS

The dual luciferase reporter gene assay showed that miR-29b-3p targeted the protein phosphatase and tensin homolog (PTEN). miR-29b-3p was downregulated and PTEN was upregulated in the brain of MCAO rats and in OGD-treated cultured neurons. MCAO rats and OGD-treated neurons showed promoted apoptosis and decreased angiogenesis, but overexpression of miR-29b-3p or silencing of PTEN could reverse these alterations. Furthermore, miR-29b-3p could negatively regulate PTEN and activate the Akt signaling pathway. BMSCs-derived exosomes also exerted protective effects against apoptosis of OGD neurons and cell apoptosis in the brain samples from MCAO rats, where we also observed promotion of angiogenesis.

CONCLUSION

BMSC-derived exosomal miR-29b-3p ameliorates ischemic brain injury by promoting angiogenesis and suppressing neuronal apoptosis, a finding which may be of great significance in the treatment of hypoxic-ischemic brain injury.

Inhibition of miR-200b-3p alleviates hypoxia-ischemic brain damage via targeting Slit2 in neonatal rats

BACKGROUND

Brain damage in premature infants often occurs in very low birth weight infants (VLBW) as a result of hypoxia-ischemia and can lead to cognitive impairment and movement disorders. Many miRNAs have been demonstrated to participate in hypoxia-ischemic brain damage (HIBD). This study was designed to investigate the roles of miR-200b-3p in brain damage of neonatal rats induced by hypoxia-ischemia.

METHODS AND RESULTS

Three-day-old SD rats were used to establish the model of hypoxia-ischemic brain injury mimicking premature infants. RT-qPCR showed that miR-200b-3p was up-regulated in rat brains at the early stage following hypoxia-ischemic treatment. Bioinformatics analysis identified that Slit2 is a target gene of miR-200b-3p and luciferase reporter gene assay confirmed that miR-200b-3p can interact with and target Slit2 mRNA. Inhibition of miR-200b-3p by antagomir increased Slit2 expression at both the mRNA and protein levels in rat brains. TUNEL assay and transmission electron microscopy (TEM) analysis showed decreased numbers of apoptotic neurons in the hypoxia-ischemia-treated animals as a result of administration of miR-200b-3p antagomir. Administration of miR-200b-3p antagomir attenuated spatial and learning memory loss in the animals induced by hypoxia-ischemia as compared to controls.

CONCLUSION

Our study has demonstrated that Slit2 is a target gene of miR-200b-3p and that the hypoxia-ischemic brain damage in neonatal rats was alleviated by inhibiting miR-200b-3p via Slit2. miR-200b-3p may be a potential therapeutic target of HIBD for further investigation.

lncRNA NEAT1 Binds to MiR-339-5p to Increase HOXA1 and Alleviate Ischemic Brain Damage in Neonatal Mice

Hypoxic-ischemic brain damage (HIBD) is a major cause of fatality and morbidity in neonates. However, current treatment approaches to alleviate HIBD are not effective. Various studies have highlighted the role of microRNAs (miRNAs) in various biological functions in multiple diseases. This study investigated the role of miR-339-5p in HIBD progression. Neonatal HIBD mouse model was induced by ligation of the right common carotid artery. Neuronal cell model exposed to oxygen-glucose deprivation (OGD) was also established. The miR-339-5p expression in mouse brain tissues and neuronal cells was quantified, and the effects of miR-339-5p on neuronal cell activity and apoptosis induced by hypoxia-ischemia were explored. The overexpression or knockdown of long non-coding RNA (lncRNA) nuclear-enriched abundant transcript 1 (NEAT1) in hippocampal neurons was used to determine the effect of lncRNA NEAT1 on the expression of miR-339-5p and homeobox A1 (HOXA1) and apoptosis. Short hairpin RNA targeting lncRNA NEAT1 and miR-339-5p antagomir were used in neonatal HIBD mice to identify their roles in HIBD. Our results revealed that miR-339-5p was downregulated in neonatal HIBD mice and neuronal cells exposed to OGD. Downregulated miR-339-5p promoted neuronal cell viability and suppressed apoptosis during hypoxia-ischemia. Moreover, lncRNA NEAT1 competitively bound to miR-339-5p to increase HOXA1 expression and inhibited neuronal cell apoptosis under hypoxic-ischemic conditions. The key observations of the current study present evidence demonstrating that lncRNA NEAT1 upregulated HOXA1 to alleviate HIBD in mice by binding to miR-339-5p.

Expression and short-term prognostic value of miR-126 and miR-182 in patients with acute stroke

Expression and short-term prognostic value of miR-126 and miR-182 in patients with acute stroke were investigated. In total, 153 patients with acute stroke admitted to the Second Affiliated Hospital of Soochow University from February 2016 to February 2018 were enrolled into the observation group as group A [88 patients with acute cerebral infarction (AIS)] or group B [65 patients with cerebral hemorrhage (ICH)]. Furthermore, 69 healthy people receiving physical examinations in the hospital were enrolled into the control group. The relative expression of miR-126 and miR-182 in all subjects were measured and their correlation with the National Institute of Health stroke scale (NIHSS) and activities of daily living (ADL) scores was analyzed. After 3 months of follow-up, the correlation of miR-126 and miR-182 with the Modified Rankin Scale (MRS) score of patients was investigated. The receiver operating characteristic (ROC) curve was employed to explore the value of miR-126 and miR-182, alone or in combination, in predicting the prognosis of acute stroke patients. Subjects in the control group had markedly higher miR-126 expression and lower miR-182 expression than those in group A and group B in the observation group (P<0.05). Pearson's correlation analysis suggested a notable correlation of miR-126 and miR-182 with NIHSS and ADL scores. Patients with a mild condition or good prognosis had higher miR-126 expression and lower miR-182 expression than patients with a severe condition or poor prognosis (P<0.05). Both miR-126 and miR-182 predicted the prognosis of acute stroke, and the combination of miR-126 and miR-182 presented better accuracy. The expression levels of miR-126 and miR-182 are associated with the neurological function, self-care ability, and prognosis in patients with acute stroke is highly valuable for predicting the prognosis of patients.

Retracted: microRNA-129-5p involved in the neuroprotective effect of dexmedetomidine on hypoxic-ischemic brain injury by targeting COL3A1 through the Wnt/β-catenin signaling pathway in neonatal rats

Our study aims to elucidate the mechanisms how microRNA-129-5p (miR-129-5p) involved in the neuroprotective effect of dexmedetomidine (DEX) on hypoxic-ischemic brain injury (HIBI) by targeting the type III procollagen gene (COL3A1) through the Wnt/β-catenin signaling pathway in neonatal rats. A total of 120 rats were obtained, among which 15 rats were selected as sham group and rest rats as model, DEX, DEX + negative control (DEX + NC), DEX + miR-129-5p mimics, DEX + miR-129-5p inhibitors, DEX + XAV-939, and DEX + miR-129-5p inhibitors + XAV-939 groups. A dual-luciferase reporter assay was performed for the target relationship between miR-129-5p and COL3A1. Weight rate and water content of cerebral hemisphere were detected. Quantitative real-time polymerase chain reaction and Western blot analysis were conducted to detect miR-129-5p expression and expressions of COL3A1, E-cadherin, T-cell factor (TCF)- 4, and β-catenin. The DEX, DEX + miR-129-5p mimics, DEX + XAV-939 groups had increased weight rate of the cerebral hemisphere, but decreased water content of left cerebral hemisphere, levels of COL3A1, β-catenin, TCF-4, and E-cadherin in the hippocampus compared with the model and DEX + miR-129-5p inhibitors groups. COL3A1 was verified as the target gene of the miR-129-5p. Compared with the DEX + NC and DEX + miR-129-5p inhibitors + XAV-939 groups, the DEX + XAV-939 and DEX + miR-129-5p mimics groups had elevated weight rate of the cerebral hemisphere, but reduced water content of left cerebral hemisphere, levels of COL3A1, β-catenin, TCF-4, and E-cadherin in the hippocampus. Our findings demonstrate that miR-129-5p improves the neuroprotective role of DEX in HIBI by targeting COL3A1 through the Wnt/β-catenin signaling pathway in neonatal rats.

The role of microRNAs in newborn brain development and hypoxic ischaemic encephalopathy

Neonates can develop hypoxic-ischaemic encephalopathy (HIE) due to lack of blood supply or oxygen, resulting in a major cause of death and disability among term newborns. However, current definitive treatment of therapeutic hypothermia, will only benefit one out of nine babies. Furthermore, the mechanisms of HIE and therapeutic hypothermia are not fully understood. Recently, microRNAs (miRNAs) have become of interest to many researchers due to their important role in post-transcriptional control and deep evolutionary history. Despite this, role of miRNAs in newborns with HIE remains largely unknown due to limited research in this field. Therefore, this review aims to understand the role of miRNAs in normal brain development and HIE pathophysiology with reliance on extrapolated data from other diseases, ages and species due to current limited data. This will provide us with an overview of how miRNAs in normal brain development changes after HIE. Furthermore, it will indicate how miRNAs are affected specifically or globally by the various pathophysiological events. In addition, we discuss about how drugs and commercially available agents can specifically target certain miRNAs as a mechanism of action and potential safety issue with off-target effects. Improving our understanding of the role of miRNAs on the cellular response after HIE would enhance the success of effective diagnosis, prognosis, and treatment of newborns with HIE.

MiR-1256 suppresses proliferation and migration of non-small cell lung cancer via regulating TCTN1

Mounting evidence has shown that miRNA expression is abnormal in various human cancers. Here, we mainly explored the biological function and the potential mechanisms of miR-1256 in non-small cell lung cancer (NSCLC). The miR-1256 mRNA expression was detected by quantitative real-time PCR and tectonic family member 1 (TCTN1) mRNA expression was detected by immunoblotting. The TCTN1 was identified to be the direct and specific target gene of miR-1256 by luciferase reporter assay. Cell proliferation was examined by methyl thiazolyl tetrazolium assay and migration was detected by transwell assay. MiR-1256 expression was downregulated in NSCLC tissues, whereas the expression of TCTN1 was upregulated, compared with normal tissues. We also found that overexpression of miR-1256 in these NSCLC cell lines inhibited cell proliferation and migration. Furthermore, TCTN1 was identified as a direct target of miR-1256 by luciferase reporter assays. Collectively, these data stated that the inhibitory effect of miR-1256 in NSCLC was realized by upregulating TCTN1, suggesting that miR-1256/TCTN1 axis may play a critical role as NSCLC therapeutic target.

A causal relationship between the neurotherapeutic effects of miR182/7a and decreased expression of PRDM5

BACKGROUND

Spinal cord injury (SCI) is terrible damage resulting in the deficiencies and necrosis of neurology and causes infinite inconvenience to sufferers. The therapy of SCI still meets a larger number of problems. Therefore, the underlying mechanism and novel therapy of acute SCI (ASCI) are urgent to explore.

MATERIALS AND METHODS

The SCI model was established in rats. The expression of miR-182/miR-7a and PRDM5 at mRNA level was detected by quantitative real-time PCR and the protein expression of PRDM5 and c-caspase 3 was assessed by western blotting assays. The apoptosis of spinal cord neurons (SCN) was assessed on flow cytometry. The transfection of cells was performed by Lipofectamine 2000 kit. The relationship between PRDM5 and miR-182/miR-7a was examined by Luciferase assay.

RESULTS

The expression of PRDM5 was up-regulated at either mRNA (2.212 folds) or protein level after SCI in rats, and knockdown of PRDM5 in SCN declined the c-caspase3 expression. In addition, the expression of miR-182 and miR-7a was decreased by 44.6% and 39.3% after SCI in rats. Moreover, the expression of miR-182 and miR-7a were negatively correlated with the level of PRDM5 expression, and the expression of PRDM5 was inhibited due to the increase of miR-182 and/or miR-7a expression. Moreover, both miR-182 and miR-7a could regulate PRDM5 to control SCN apoptosis. According to the BBB score increased 2 folds, the intrathecal injection of miR-182 and miR-7a improved the neurological function of rats.

CONCLUSION

Inhibition of PRDM5 which was apparently negative correlation with miR-182 and miR-7a could suppress the neurons apoptosis to attenuate acute spinal cord injury in rats.

Regulation of mRNA following brain ischemia and reperfusion

There is growing appreciation that mRNA regulation plays important roles in disease and injury. mRNA regulation and ribonomics occur in brain ischemia and reperfusion (I/R) following stroke and cardiac arrest and resuscitation. It was recognized over 40 years ago that translation arrest (TA) accompanies brain I/R and is now recognized as part of the intrinsic stress responses triggered in neurons. However, neuron death correlates to a prolonged TA in cells fated to undergo delayed neuronal death (DND). Dysfunction of mRNA regulatory processes in cells fated to DND prevents them from translating stress-induced mRNAs such as heat shock proteins. The morphological and biochemical studies of mRNA regulation in postischemic neurons are discussed in the context of the large variety of molecular damage induced by ischemic injury. Open issues and areas of future investigation are highlighted. A sober look at the molecular complexity of ischemia-induced neuronal injury suggests that a network framework will assist in making sense of this complexity. The ribonomic network sits between the gene network and the various protein and metabolic networks. Thus, targeting the ribonomic network may prove more effective at neuroprotection than targeting specific molecular pathways, for which all efforts have failed to the present time to stop DND in stroke and after cardiac arrest. WIREs RNA 2017, 8:e1415. doi: 10.1002/wrna.1415 For further resources related to this article, please visit the WIREs website.

MicroRNA: Small RNA mediators of the brains genomic response to environmental stress

The developmental processes that establish the synaptic architecture of the brain while retaining capacity for activity-dependent remodeling, are complex and involve a combination of genetic and epigenetic influences. Dysregulation of these processes can lead to problems with neural circuitry which manifest in humans as a range of neurodevelopmental syndromes, such as schizophrenia, bipolar disorder and fragile X mental retardation. Recent studies suggest that prenatal, postnatal and intergenerational environmental factors play an important role in the aetiology of stress-related psychopathology. A number of these disorders have been shown to display epigenetic changes in the postmortem brain that reflect early life experience. These changes affect the regulation of gene expression though chromatin remodeling (transcriptional) and post-transcriptional influences, especially small noncoding microRNA (miRNA). These dynamic and influential molecules appear to play an important function in both brain development and its adaption to stress. In this review, we examine the role of miRNA in mediating the brain's response to both prenatal and postnatal environmental perturbations and explore how stress- induced alterations in miRNA expression can regulate the stress response via modulation of the immune system. Given the close relationship between environmental stress, miRNA, and brain development/function, we assert that miRNA hold a significant position at the molecular crossroads between neural development and adaptations to environmental stress. A greater understanding of the dynamics that mediate an individual's predisposition to stress-induced neuropathology has major human health benefits and is an important area of research.

The Emerging Role of Epigenetics in Cerebral Ischemia

Despite great progresses in the treatment and prevention of ischemic stroke, it is still among the leading causes of death and serious long-term disability all over the world, indicating that innovative neural regenerative and neuroprotective agents are urgently needed for the development of therapeutic approaches with greater efficacy for ischemic stroke. More and more evidence suggests that a spectrum of epigenetic processes play an important role in the pathophysiology of cerebral ischemia. In the present review, we first discuss recent developments in epigenetic mechanisms, especially their roles in the pathophysiology of cerebral ischemia. Specifically, we focus on DNA methylation, histone deacetylase, histone methylation, and microRNAs (miRNAs) in the regulation of vascular and neuronal regeneration after cerebral ischemia. Additionally, we highlight epigenetic strategies for ischemic stroke treatments, including the inhibition of histone deacetylase enzyme and DNA methyltransferase activities, and miRNAs. These therapeutic strategies are far from clinic use, but preliminary data indicate that neuroprotective agents targeting these pathways can modulate neural cell regeneration and promote brain repair and functional recovery after cerebral ischemia. A better understanding of how epigenetics influences the process and progress of cerebral ischemia will pave the way for discovering more sensitive and specific biomarkers and new targets and therapeutics for ischemic stroke.

Neonatal hypoxic ischemic encephalopathy-related biomarkers in serum and cerebrospinal fluid

Neonatal hypoxic ischemic encephalopathy (HIE) is a common disease caused by perinatal asphyxia, a major cause of neonatal death, neurological behavior, and long-term disability. Currently, the diagnosis and prognosis of neonatal HIE are based on nervous system clinical manifestations, imaging and electrophysiological examination. These take time and late diagnosis allows brain injury to occur in newborns, so that infants of many brain injury missed the best treatment time, left with varying degrees of neurological sequelae. The use of biomarkers to monitor brain injury and evaluate neuroprotective effects might allow the early intervention and treatment of neonatal HIE to reduce mortality rates. This study reviewed the mechanism of neonatal hypoxic ischemic encephalopathy in relation to numerous brain-related biomarkers including NSE, S-100β, GFAP, UCH-L1, Tau protein, miRNA, LDH, and CK-BB. In early diagnosis of neonatal HIE, S-100β and activin A seems to be better biomarkers. Biomarkers with the greatest potential to predict long-term neurologic handicap of neonates with HIE are GFAP and UCH-L1 and when combined with other markers or brain imaging can increase the detection rate of HIE. Tau protein is a unique biological component of nervous tissues, and might have value for neonatal HIE diagnosis. Combination of more than two biological markers should be a future research direction.

Detection and quantification of microRNA in cerebral microdialysate

Background

Secondary brain injury accounts for a major part of the morbidity and mortality in patients with spontaneous aneurysmal subarachnoid hemorrhage (SAH), but the pathogenesis and pathophysiology remain controversial. MicroRNAs (miRNAs) are important posttranscriptional regulators of complementary mRNA targets and have been implicated in the pathophysiology of other types of acute brain injury. Cerebral microdialysis is a promising tool to investigate these mechanisms. We hypothesized that miRNAs would be present in human cerebral microdialysate.

Methods

RNA was extracted and miRNA profiles were established using high throughput real-time quantification PCR on the following material: 1) Microdialysate sampled in vitro from A) a solution of total RNA extracted from human brain, B) cerebrospinal fluid (CSF) from a neurologically healthy patient, and C) a patient with SAH; and 2) cerebral microdialysate and CSF sampled in vivo from two patients with SAH. MiRNAs were categorized according to their relative recovery (RR) and a pathway analysis was performed for miRNAs exhibiting a high RR in vivo.

Results

Seventy-one of the 160 miRNAs detected in CSF were also found in in vivo microdialysate from SAH patients. Furthermore specific miRNAs consistently exhibited either a high or low RR in both in vitro and in vivo microdialysate. Analysis of repeatability showed lower analytical variation in microdialysate than in CSF.

Conclusions

MiRNAs are detectable in cerebral microdialysate; a large group of miRNAs consistently showed a high RR in cerebral microdialysate. Measurement of cerebral interstitial miRNA concentrations may aid in the investigation of secondary brain injury in neurocritical conditions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0505-1) contains supplementary material, which is available to authorized users.