Embryonic lethal abnormal vision proteins and adenine and uridine-rich element mRNAs after global cerebral ischemia and reperfusion in the rat

The Use of Identified Hypoxia-related Genes to Generate Models for Predicting the Prognosis of Cerebral Ischemia‒reperfusion Injury and Developing Treatment Strategies

Cerebral ischemia‒reperfusion injury (CIRI) is a type of secondary brain damage caused by reperfusion after ischemic stroke due to vascular obstruction. In this study, a CIRI diagnostic model was established by identifying hypoxia-related differentially expressed genes (HRDEGs) in patients with CIRI. The ischemia‒reperfusion injury (IRI)-related datasets were downloaded from the Gene Expression Omnibus (GEO) database ( http://www.ncbi.nlm.nih.gov/geo ), and hypoxia-related genes in the Gene Cards database were identified. After the datasets were combined, hypoxia-related differentially expressed genes (HRDEGs) expressed in CIRI patients were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of the HRDEGs were performed using online tools. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were performed with the combined gene dataset. CIRI diagnostic models based on HRDEGs were constructed via least absolute shrinkage and selection operator (LASSO) regression analysis and a support vector machine (SVM) algorithm. The efficacy of the 9 identified hub genes for CIRI diagnosis was evaluated via mRNA‒microRNA (miRNA) interaction, mRNA-RNA-binding protein (RBP) network interaction, immune cell infiltration, and receiver operating characteristic (ROC) curve analyses. We then performed logistic regression analysis and constructed logistic regression models based on the expression of the 9 HRDEGs. We next established a nomogram and calibrated the prediction data. Finally, the clinical utility of the constructed logistic regression model was evaluated via decision curve analysis (DCA). This study revealed 9 critical genes with high diagnostic value, offering new insights into the diagnosis and selection of therapeutic targets for patients with CIRI. : Not applicable.

RNA regulation of inflammatory responses in glia and its potential as a therapeutic target in central nervous system disorders

A major hallmark of neuroinflammation is the activation of microglia and astrocytes with the induction of inflammatory mediators such as IL-1β, TNF-α, iNOS, and IL-6. Neuroinflammation contributes to disease progression in a plethora of neurological disorders ranging from acute CNS trauma to chronic neurodegenerative disease. Posttranscriptional pathways of mRNA stability and translational efficiency are major drivers for the expression of these inflammatory mediators. A common element in this level of regulation centers around the adenine- and uridine-rich element (ARE) which is present in the 3' untranslated region (UTR) of the mRNAs encoding these inflammatory mediators. (ARE)-binding proteins (AUBPs) such as Human antigen R (HuR), Tristetraprolin (TTP) and KH- type splicing regulatory protein (KSRP) are key nodes for directing these posttranscriptional pathways and either promote (HuR) or suppress (TTP and KSRP) glial production of inflammatory mediators. This review will discuss basic concepts of ARE-mediated RNA regulation and its impact on glial-driven neuroinflammatory diseases. We will discuss strategies to target this novel level of gene regulation for therapeutic effect and review exciting preliminary studies that underscore its potential for treating neurological disorders.

Deficiency of the RNA-binding protein ELAVL1/HuR leads to the failure of endogenous and exogenous neuroprotection of retinal ganglion cells

Introduction

ELAVL1/HuR is a keystone regulator of gene expression at the posttranscriptional level, including stress response and homeostasis maintenance. The aim of this study was to evaluate the impact of hur silencing on the age-related degeneration of retinal ganglion cells (RGC), which potentially describes the efficiency of endogenous neuroprotection mechanisms, as well as to assess the exogenous neuroprotection capacity of hur-silenced RGC in the rat glaucoma model.

Methods

The study consisted of in vitro and in vivo approaches. In vitro, we used rat B-35 cells to investigate, whether AAV-shRNA-HuR delivery affects survival and oxidative stress markers under temperature and excitotoxic insults. In vivo approach consisted of two different settings. In first one, 35 eight-week-old rats received intravitreal injection of AAV-shRNA-HuR or AAV-shRNA scramble control. Animals underwent electroretinography tests and were sacrificed 2, 4 or 6 months after injection. Retinas and optic nerves were collected and processed for immunostainings, electron microscopy and stereology. For the second approach, animals received similar gene constructs. To induce chronic glaucoma, 8 weeks after AAV injection, unilateral episcleral vein cauterization was performed. Animals from each group received intravitreal injection of metallothionein II. Animals underwent electroretinography tests and were sacrificed 8 weeks later. Retinas and optic nerves were collected and processed for immunostainings, electron microscopy and stereology.

Results

Silencing of hur induced apoptosis and increased oxidative stress markers in B-35 cells. Additionally, shRNA treatment impaired the cellular stress response to temperature and excitotoxic insults. In vivo, RGC count was decreased by 39% in shRNA-HuR group 6 months after injection, when compared to shRNA scramble control group. In neuroprotection study, the average loss of RGCs was 35% in animals with glaucoma treated with metallothionein and shRNA-HuR and 11.4% in animals with glaucoma treated with metallothionein and the scramble control shRNA. An alteration in HuR cellular content resulted in diminished photopic negative responses in the electroretinogram.

Conclusions

Based on our findings, we conclude that HuR is essential for the survival and efficient neuroprotection of RGC and that the induced alteration in HuR content accelerates both the age-related and glaucoma-induced decline in RGC number and function, further confirming HuR's key role in maintaining cell homeostasis and its possible involvement in the pathogenesis of glaucoma.

Emodin relieves hypoxia-triggered injury via elevation of microRNA-25 in PC-12 cells

Emodin (EMO) possesses extensive pharmacological activities, which has been proven to exert the protective impact in diverse nervous system diseases. Nonetheless, whether EMO emerges a neuro-protective activity in hypoxic-evoked ischemic brain injury is still further probed. The intention of the research is to disclose whether EMO emerges neuro-protective activity in hypoxic-evoked ischemic brain injury. PC-12 received hypoxia administration, and then cell viability, apoptosis and autophagy were estimated. After EMO disposition, the above-involved cellular processes were evaluated again. MiR-25 functions in EMO-affected cells were also estimated. The interrelation between miR-25 and neurofilament light-chain polypeptide gene (NEFL) and the conceivable roles of NEFL in hypoxia-disposed cells were investigated. The latent mechanism was uncovered by mTOR and Notch pathways determination. Hypoxia triumphantly triggered apoptosis and autophagy, but EMO repressed these functions in PC-12 cells. Increased miR-25 was induced by EMO, and inhibited miR-25 abated the impacts of EMO on hypoxia-disposed PC-12 cells. NEFL as a neoteric target gene of miR-25 was predicated, and overexpressed NEFL annulled the functions of EMO in hypoxia-injured cells. EMO activated mTOR and Notch pathways through repressing NEFL. The investigations corroborated that EMO weakened hypoxia-triggered injury via elevating miR-25 by targeting NEFL in PC-12 cells.