MicroRNA 223 Targeting ATG16L1 Affects Microglial Autophagy in the Kainic Acid Model of Temporal Lobe Epilepsy

Status epilepticus alters hippocampal ultrastructure in kainic acid rat model

Kainic acid (KA) model of epilepsy is a reliable tool to study temporal lobe epilepsy (TLE), the most common type of partial epilepsy in adults. Substantial body of data suggest that the KA-induced status epilepticus (SE) leads to several molecular and structural changes in the hippocampus, including sclerosis, sprouting of mossy fiber, reorganization of inter-neuronal networks, alterations in neuropeptide signaling, gliosis, and synaptic transmission dysregulation. However, no details on the ultrastructural changes, especially in relationship to synapses are available. This information is important in providing a comprehensive understanding of subtle changes that occur in this debilitating disease. Thus, in this study, applying electron-microscopic morphometric analysis, we evaluated the ultrastructural effects of KA on the CA1 region of the hippocampus, an area intimately involved in SE. The total number of synaptic vesicles (SVs), the number of docking SVs, the length of synapse active zone (AZ) and the number and area of presynaptic and postsynaptic mitochondria in axo-dendritic (excitatory) synapses were measured at 24 h, and 8 and 21 days after KA administration. Results indicate a decrease in the total number and docking of SVs, an increase in the length of AZ and the number and area of presynaptic and postsynaptic mitochondria, which were more prominent at 8 days after KA injection. The findings suggest a time-dependent ultrastructural changes in CA1 region of the hippocampus in an animal model of focal epilepsy.

Autophagy-related genes in mesial temporal lobe epilepsy: an integrated bioinformatics analysis

BACKGROUND

Autophagy plays essential roles in the development and pathogenesis of mesial temporal lobe epilepsy (mTLE). In this research, we aim to identify and validate the autophagy-related genes associated with mTLE through bioinformatics analysis and experimental validations.

METHODS

We obtained the dataset GSE143272 and high-throughput sequencing results of mTLE from public databases. Potential differentially expressed autophagy-related genes related to mTLE were identified using R software. Subsequently, genomes pathway enrichment analysis, protein-protein interactions (PPIs), and the gene ontology (GO) enrichment were performed for the selected autophagy-related genes. The mRNA expression profiles of hub genes were then used to establish a least absolute shrinkage and selection operator (LASSO) model. Finally, seven hub candidate autophagy-related genes were confirmed in hippocampus using the lithium-pilocarpine chronic epilepsy model.

RESULTS

A total of 40 differential expression genes (DEGs) among the core autophagy-related genes were identified. The analysis results of PPI revealed that interactions among these DEGs. KEGG pathway and GO analysis of selected candidate autophagy-related genes indicated that those enriched terms mainly focused on macroautophagy, regulation of autophagy, cellular response to extracellular stimulus and mitochondrion disassembly. The results suggested that SQSTM1, VEGFA, BNIP and WIPI2 were consistent with the bioinformatics analysis. The expression levels of SQSTM1 and VEGFA in epilepsy model samples were significantly higher than those in normal control, while BNIP and WIPI2 expression levels were notably decreased. The final hub gene-based LASSO regression model accurately predicted the occurrence of epilepsy (AUC = 0.88).

CONCLUSIONS

Through bioinformatics analysis of public data, we identified 40 candidate autophagy-related genes associated with mTLE. SQSTM1, VEGFA, BNIP and WIPI2 may play significant roles in autophagy, influencing the onset and development of mTLE by regulating autophagy pathway. These findings deepen our understanding of mTLE, and may serve as sensitive and valuable indicators for the prognosis and diagnosis of this condition.

The emerging role of miRNAs in epilepsy: From molecular signatures to diagnostic potential

Epilepsy is a medical condition characterized by intermittent seizures accompanied by changes in consciousness. Epilepsy significantly impairs the daily functioning and overall well-being of affected individuals. Epilepsy is a chronic neurological disorder characterized by recurrent seizures resulting from various dysfunctions in brain activity. The molecular processes underlying changes in neuronal structure, impaired apoptotic responses in neurons, and disruption of regenerative pathways in glial cells in epilepsy remain unknown. MicroRNAs (miRNAs) play a crucial role in regulating apoptosis, autophagy, oxidative stress, neuroinflammation, and the body's regenerative and immune responses. miRNAs have been shown to influence many pathogenic processes in epilepsy including inflammatory responses, neuronal necrosis and apoptosis, dendritic growth, synaptic remodeling, and other processes related to the development of epilepsy. Therefore, the purpose of our current analysis was to determine the role of miRNAs in the etiology and progression of epilepsy. Furthermore, they have been examined for their potential application as biomarkers and therapeutic targets.

Epigenetic regulation in epilepsy: A novel mechanism and therapeutic strategy for epilepsy

Epilepsy is a common neurological disorder characterized by recurrent seizures with excessive and abnormal neuronal discharges. Epileptogenesis is usually involved in neuropathological processes such as ion channel dysfunction, neuronal injury, inflammatory response, synaptic plasticity, gliocyte proliferation and mossy fiber sprouting, currently the pathogenesis of epilepsy is not yet completely understood. A growing body of studies have shown that epigenetic regulation, such as histone modifications, DNA methylation, noncoding RNAs (ncRNAs), N6-methyladenosine (m6A) and restrictive element-1 silencing transcription factor/neuron-restrictive silencing factor (REST/NRSF) are also involved in epilepsy. Through epigenetic studies, we found that the synaptic dysfunction, nerve damage, cognitive dysfunction and brain development abnormalities are affected by epigenetic regulation of epilepsy-related genes in patients with epilepsy. However, the functional roles of epigenetics in pathogenesis and treatment of epilepsy are still to be explored. Therefore, profiling the array of genes that are epigenetically dysregulated in epileptogenesis is likely to advance our understanding of the mechanisms underlying the pathophysiology of epilepsy and may for the amelioration of these serious human conditions provide novel insight into therapeutic strategies and diagnostic biomarkers for epilepsy to improve serious human condition.

Stabilization of mitochondrial function by chlorogenic acid protects against kainic acid-induced seizures and neuronal cell death in rats

The current study investigated the effect of chlorogenic acid, a polyphenolic compound found in numerous plant products, on a kainic acid-induced seizure rat model and its potential mechanism. Rats were administered chlorogenic acid (10 and 50 mg/kg) intraperitoneally for 30 min before kainic acid (15 mg/kg) intraperitoneal administration. Pretreatment with chlorogenic acid decreased the seizure score, increased the latency to onset of the first seizure, and decreased the mortality rate. Chlorogenic acid pretreatment also resulted in a significant reduction in glutamate elevation and neuronal death in the hippocampus of kainic acid-treated rats. In addition, electron microscopy revealed that kainic acid-induced changes in hippocampal mitochondrial structure were prevented by chlorogenic acid pretreatment. Additionally, the levels of mitochondrial function-related proteins, including sirtuin 3, Complex I, glutamate dehydrogenase 1 and ATP synthase, were increased, and the level of the mitochondrial damage marker cytochrome C was decreased in the hippocampus of chlorogenic acid/kainic acid rats. Furthermore, the expression of mitochondrial biogenesis-related proteins [AMP-activated protein kinase (AMPK), sirtuin1, and peroxisome proliferator-activated receptor γ-coactivator-1α (PGC-1α)] and mitophagy-related proteins [phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1), Parkin, and microtubule-associated protein 1 light chain 3 (LC3)] was decreased in the hippocampus of kainic acid-treated rats, which was reversed by chlorogenic acid pretreatment. These observations reveal the marked neuroprotective potential of chlorogenic acid against kainic acid-induced neurotoxicity and seizures through prevention of glutamate increase and preservation of AMPK/sirtuin 1/PGC-1α-mediated mitochondrial biogenesis and PINK1/Parkin-induced mitophagy to maintain adequate mitochondrial homeostasis and function.

RNA therapeutics for epilepsy: An emerging modality for drug discovery

Drug discovery in epilepsy began with the finding of potassium bromide by Sir Charles Locock in 1857. The following century witnessed the introduction of phenotypic screening tests for discovering antiseizure medications (ASMs). Despite the high success rate of developing ASMs, they have so far failed in eliminating drug resistance and in delivering disease-modifying treatments. This emphasizes the need for new drug discovery strategies in epilepsy. RNA-based drugs have recently shown promise as a new modality with the potential of providing disease modification and counteracting drug resistance in epilepsy. RNA therapeutics can be directed either toward noncoding RNAs, such as microRNAs, long noncoding RNAs (ncRNAs), and circular RNAs, or toward messenger RNAs. The former show promise in sporadic, nongenetic epilepsies, as interference with ncRNAs allows for modulation of entire disease pathways, whereas the latter seem more promising in monogenic childhood epilepsies. Here, we describe therapeutic strategies for modulating disease-associated RNA molecules and highlight the potential of RNA therapeutics for the treatment of different patient populations such as sporadic, drug-resistant epilepsy, and childhood monogenic epilepsies.

Evaluation of MicroRNAs in Pediatric Epilepsy

OBJECTIVE

The pathophysiology of epilepsy remains unknown. Recent research has shown that microRNA expression changes in epileptic adults. In the present work, we aimed to identify serum microRNA expression in drug-responsive and resistant children with idiopathic general- ized epilepsy.

MATERIALS AND METHODS

The study included 43 (20 male and 23 female) epilepsy patients and 66 (43 male and 23 female) control subjects. The mean ages of the groups were 113.41 ± 61.83 and 105.46 ± 62.31 months, respectively. Twenty-eight epileptic patients were classi- fied as drug resistant. Thirteen of the controls were the siblings of patients with epilepsy. The study only included children with idiopathic generalized epilepsy who had normal brain mag- netic resonance imaging. The serum microRNA expressions (microRNA-181a, microRNA-155, microRNA-146, and microRNA-223) were investigated. Expressions of serum microRNA-181a, microRNA-155, microRNA-146, and microRNA-223 were previously investigated in epilepsy patients and children with febrile seizures. Therefore, these microRNAs were chosen. The expressions of serum levels of microRNAs were determined using quantitative real-time poly- merase chain reaction.

RESULTS

The results indicated that the expressions of serum microRNA-155 and microRNA-223 were elevated in epileptic children (P < .05). The expression of the same microRNAs was also elevated in individuals with drug-resistant epilepsy compared to healthy controls (P < .05). microRNA-146a, microRNA-155, and microRNA-223 expressions were higher in drug-resistant patients than in drug-responsive children (P < .05). A logistic regression study determined that an increase of microRNA-155 was a risk for epilepsy, while a decrease of microRNA-146a risk for epilepsy.

CONCLUSION

Few researchers have investigated the function of microRNAs in the develop- ment of childhood epilepsy. Our findings revealed that epilepsy patients have abnormal microRNAexpression.

Molecular Mechanism and Regulation of Autophagy and Its Potential Role in Epilepsy

Autophagy is an evolutionally conserved degradation mechanism for maintaining cell homeostasis whereby cytoplasmic components are wrapped in autophagosomes and subsequently delivered to lysosomes for degradation. This process requires the concerted actions of multiple autophagy-related proteins and accessory regulators. In neurons, autophagy is dynamically regulated in different compartments including soma, axons, and dendrites. It determines the turnover of selected materials in a spatiotemporal control manner, which facilitates the formation of specialized neuronal functions. It is not surprising, therefore, that dysfunctional autophagy occurs in epilepsy, mainly caused by an imbalance between excitation and inhibition in the brain. In recent years, much attention has been focused on how autophagy may cause the development of epilepsy. In this article, we overview the historical landmarks and distinct types of autophagy, recent progress in the core machinery and regulation of autophagy, and biological roles of autophagy in homeostatic maintenance of neuronal structures and functions, with a particular focus on synaptic plasticity. We also discuss the relevance of autophagy mechanisms to the pathophysiology of epileptogenesis.

Comprehensive analysis of ncRNA involvement in brain microglia immunology

Microglia is a major class of brain-resident myeloid cells and non-coding RNAs (ncRNAs) serves as key regulators in microglia homeostasis and inflammatory process. Here, we constructed the systematical association between microglia and ncRNAs including miRNAs, lncRNAs and circRNAs from two aspects, manual retrieval and computational detection. A total of 648 experimental verified ncRNA-microglia associations were obtained from published studies, including ncRNA regulatory patterns within different experimental models. Furthermore, we extracted 9 miRNA and 1 lncRNA expression profiles from the GEO database. Also, we obtained 31 sample-match miRNA and mRNA expression profiles, containing a total of 2335 normal or disordered brain samples. Finally, we developed a platform named MG-ncRexplorer (http://bio-bigdata.hrbmu.edu.cn/MG-ncRexplorer/), exploring the associations between ncRNAs and microglia among experimental validated and computational detection. To demonstrate the usage of MG-ncRexplorer, we constructed regulatory target networks based on manual retrieval associations and identified risk glioma miRNAs among multiple high-throughput expression profiles.

Specific microRNAs for Modulation of Autophagy in Spinal Cord Injury

The treatment of spinal cord injury (SCI) is currently a major challenge, with a severe lack of effective therapies for yielding meaningful improvements in function. Therefore, there is a great opportunity for the development of novel treatment strategies for SCI. The modulation of autophagy, a process by which a cell degrades and recycles unnecessary or harmful components (protein aggregates, organelles, etc.) to maintain cellular homeostasis and respond to a changing microenvironment, is thought to have potential for treating many neurodegenerative conditions, including SCI. The discovery of microRNAs (miRNAs), which are short ribonucleotide transcripts for targeting of specific messenger RNAs (mRNAs) for silencing, shows prevention of the translation of mRNAs to the corresponding proteins affecting various cellular processes, including autophagy. The number of known miRNAs and their targets continues to grow rapidly. This review article aims to explore the relationship between autophagy and SCI, specifically with the intent of identifying specific miRNAs that can be useful to modulate autophagy for neuroprotection and the improvement of functional recovery in SCI.