Expression analysis of beta-secretase 1 (BACE1) and its naturally occurring antisense (BACE1-AS) in blood of epileptic patients

The role of axon guidance molecules in the pathogenesis of epilepsy

Current treatments for epilepsy can only manage the symptoms of the condition but cannot alter the initial onset or halt the progression of the disease. Consequently, it is crucial to identify drugs that can target novel cellular and molecular mechanisms and mechanisms of action. Increasing evidence suggests that axon guidance molecules play a role in the structural and functional modifications of neural networks and that the dysregulation of these molecules is associated with epilepsy susceptibility. In this review, we discuss the essential role of axon guidance molecules in neuronal activity in patients with epilepsy as well as the impact of these molecules on synaptic plasticity and brain tissue remodeling. Furthermore, we examine the relationship between axon guidance molecules and neuroinflammation, as well as the structural changes in specific brain regions that contribute to the development of epilepsy. Ample evidence indicates that axon guidance molecules, including semaphorins and ephrins, play a fundamental role in guiding axon growth and the establishment of synaptic connections. Deviations in their expression or function can disrupt neuronal connections, ultimately leading to epileptic seizures. The remodeling of neural networks is a significant characteristic of epilepsy, with axon guidance molecules playing a role in the dynamic reorganization of neural circuits. This, in turn, affects synapse formation and elimination. Dysregulation of these molecules can upset the delicate balance between excitation and inhibition within a neural network, thereby increasing the risk of overexcitation and the development of epilepsy. Inflammatory signals can regulate the expression and function of axon guidance molecules, thus influencing axonal growth, axon orientation, and synaptic plasticity. The dysregulation of neuroinflammation can intensify neuronal dysfunction and contribute to the occurrence of epilepsy. This review delves into the mechanisms associated with the pathogenicity of axon guidance molecules in epilepsy, offering a valuable reference for the exploration of therapeutic targets and presenting a fresh perspective on treatment strategies for this condition.

Mechanisms of microRNA-132 in central neurodegenerative diseases: A comprehensive review

MicroRNA-132 (miR-132) is a highly conserved molecule that plays a crucial regulatory role in central nervous system (CNS) disorders. The expression levels of miR-132 exhibit variability in various neurological disorders and have been closely linked to disease onset and progression. The expression level of miR-132 in the CNS is regulated by a diverse range of stimuli and signaling pathways, including neuronal migration and integration, dendritic outgrowth, and complexity, synaptogenesis, synaptic plasticity, as well as inflammation and apoptosis activation. The aberrant expression of miR-132 in various central neurodegenerative diseases has garnered widespread attention. Clinical studies have revealed altered miR-132 expression levels in both chronic and acute CNS diseases, positioning miR-132 as a potential biomarker or therapeutic target. An in-depth exploration of miR-132 holds the promise of enhancing our understanding of the mechanisms underlying CNS diseases, thereby offering novel insights and strategies for disease diagnosis and treatment. It is anticipated that this review will assist researchers in recognizing the potential value of miR-132 and in generating innovative ideas for clinical trials related to CNS degenerative diseases.

Tackling seizures in patients with Alzheimer's disease

INTRODUCTION

In past years, a possible bidirectional link between epilepsy and Alzheimer's disease (AD) has been proposed: if AD patients are more likely to develop epilepsy, people with late-onset epilepsy evidence an increased risk of dementia. Furthermore, current research suggested that subclinical epileptiform discharges may be more frequent in patients with AD and network hyperexcitability may hasten cognitive impairment.

AREAS COVERED

In this narrative review, the authors discuss the recent evidence linking AD and epilepsy as well as seizures semeiology and epileptiform activity observed in patients with AD. Finally, anti-seizure medications (ASMs) and therapeutic trials to tackle seizures and network hyperexcitability in this clinical scenario have been summarized.

EXPERT OPINION

There is growing experimental evidence demonstrating a strong connection between seizures, neuronal hyperexcitability, and AD. Epilepsy in AD has shown a good response to ASMs both at the late and prodromal stages. The new generation ASMs with fewer cognitive adverse effects seem to be a preferable option. Data on the possible effects of network hyperexcitability and ASMs on AD progression are still inconclusive. Further clinical trials are mandatory to identify clear guidelines about treatment of subclinical epileptiform discharges in patients with AD without seizures.

Alzheimer's disease and epilepsy: An increasingly recognized comorbidity

Both Alzheimer's disease (AD) and epilepsy are common chronic diseases in older people. Seizures and epileptiform discharges are very prevalent in AD and can occur since any stage of AD. Increasing evidence indicates that AD and epilepsy may be comorbid. Several factors may be related to the underlying mechanism of the comorbidity. Identifying seizures in patients with AD is a challenge because seizures are often clinically non-motor and may overlap with some AD symptoms. Not only seizures but also epileptiform discharges may exacerbate the cognitive decline in AD patients, highlighting the importance of early recognition and treatment. This review provides a comprehensive overview of seizures in AD from multiple aspects to provide more insight.

BACE1: More than just a β-secretase

β-site amyloid precursor protein cleaving enzyme-1 (BACE1) research has historically focused on its actions as the β-secretase responsible for the production of β-amyloid beta, observed in Alzheimer's disease. Although the greatest expression of BACE1 is found in the brain, BACE1 mRNA and protein is also found in many cell types including pancreatic β-cells, adipocytes, hepatocytes, and vascular cells. Pathologically elevated BACE1 expression in these cells has been implicated in the development of metabolic diseases, including type 2 diabetes, obesity, and cardiovascular disease. In this review, we examine key questions surrounding the BACE1 literature, including how is BACE1 regulated and how dysregulation may occur in disease, and understand how BACE1 regulates metabolism via cleavage of a myriad of substrates. The phenotype of the BACE1 knockout mice models, including reduced weight gain, increased energy expenditure, and enhanced leptin signaling, proposes a physiological role of BACE1 in regulating energy metabolism and homeostasis. Taken together with the weight loss observed with BACE1 inhibitors in clinical trials, these data highlight a novel role for BACE1 in regulation of metabolic physiology. Finally, this review aims to examine the possibility that BACE1 inhibitors could provide a innovative treatment for obesity and its comorbidities.

Alzheimer's Disease and microRNA-132: A Widespread Pathological Factor and Potential Therapeutic Target

Alzheimer's disease (AD) is a common neurodegenerative disease in the elderly and is the most common type of dementia. AD is mostly gradual onset, and involves slow, progressive mental decline, accompanied by personality changes; the incidence of AD gradually increases with age. The etiology of AD is unknown, although it is currently believed to be related to abnormal deposition of amyloid β-protein (Aβ) in the brain, hyperphosphorylation of microtubule-associated protein tau, and the release of various cytokines, complements, activators and chemokines by cells. MicroRNAs (miRNAs) are a class of highly conserved non-coding RNAs that regulate gene expression at the post-transcriptional level, and manipulate the functions of intracellular proteins and physiological processes. Emerging studies have shown that miRNA plays an important role in regulating AD-related genes. MiR-132 is known as "NeurimmiR" due to its involvement in numerous neurophysiological and pathological processes. Accumulating pre-clinical results suggest that miR-132 may be involved in the progression of Aβ and tau pathology. Moreover, clinical studies have indicated that decreased circulating miR-132 levels could be used a potential diagnostic biomarker in AD. Here, we review the pathogenic role of miR-132 activity in AD, and the potential of targeting miR-132 for developing future therapeutic strategies.

The function of SUMOylation and its crucial roles in the development of neurological diseases

Neurological diseases are relatively complex diseases of a large system; however, the detailed mechanism of their pathogenesis has not been completely elucidated, and effective treatment methods are still lacking for some of the diseases. The SUMO (small ubiquitin-like modifier) modification is a dynamic and reversible process that is catalyzed by SUMO-specific E1, E2, and E3 ligases and reversed by a family of SENPs (SUMO/Sentrin-specific proteases). SUMOylation covalently conjugates numerous cellular proteins, and affects their cellular localization and biological activity in numerous cellular processes. A wide range of neuronal proteins have been identified as SUMO substrates, and the disruption of SUMOylation results in defects in synaptic plasticity, neuronal excitability, and neuronal stress responses. SUMOylation disorders cause many neurodegenerative diseases, such as Parkinson's disease, Alzheimer's disease, and Huntington's disease. By modulating the ion channel subunit, SUMOylation imbalance is responsible for the development of various channelopathies. The regulation of protein SUMOylation in neurons may provide a new strategy for the development of targeted therapeutic drugs for neurodegenerative diseases and channelopathies.

Long Non-Coding RNA BACE1-AS Modulates Isoflurane-Induced Neurotoxicity to Alzheimer's Disease Through Sponging miR-214-3p

Isoflurane, an anesthetic, can aggravate the progression of Alzheimer's disease (AD). Long non-coding RNA β-secretase 1 (BACE1)-antisense transcript (BACE1-AS) and miR-214-3p are related to AD progression. Nevertheless, it is unclear whether BACE1-AS is involved in the development of isoflurane-mediated AD via miR-214-3p. Amyloid beta peptide (Aβ) was employed to construct the AD cell model. The expression of BACE1-AS and miR-214-3p in the plasma of AD patients and SK-N-SH and SK-N-AS cells treated with Aβ and isoflurane was assessed through quantitative reverse transcription polymerase chain reaction (qRT-PCR). The proliferation and apoptosis of Aβ-treated SK-N-SH and SK-N-AS cells were determined via 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) or flow cytometry assays, respectively. Protein levels of B cell lymphoma 2 (Bcl-2), Bcl-2-associated X (Bax), CyclinD1, microtubule-associated protein A1/1B-light chain3 (LC3 I/LC3 II), p62 and Beclin1 were detected via western blot analysis. The relationship between BACE1-AS and miR-214-3p was verified by dual-luciferase reporter assay. We found that BACE1-AS was upregulated and miR-214-3p was downregulated in the plasma of AD patients and SK-N-SH and SK-N-AS cells treated with Aβ and isoflurane. Both BACE1-AS depletion and miR-214-3p augmentation restored the suppression of proliferation and the facilitation of apoptosis and autophagy of Aβ-treated SK-N-SH and SK-N-AS cells induced by isoflurane. Importantly, BACE1-AS acted as a sponge for miR-214-3p. Additionally, miR-214-3p silencing reversed the influence of BACE1-AS knockdown on isoflurane-mediated proliferation, apoptosis and autophagy in Aβ-induced SK-N-SH and SK-N-AS cells. In conclusion, BACE1-AS aggravated isoflurane-induced neurotoxicity to AD via sponging miR-214-3p.

Suppression of BACE1 and amyloidogenic/RAGE axis by sitagliptin ameliorates PTZ kindling-induced cognitive deficits in rats

The debilitating nature of cognitive impairment in epilepsy and the potential of some traditional antiepileptics to further deteriorate cognitive function are areas of growing concern. Glucagon-like peptide-1 (GLP-1) deficiency has been linked to reduced seizure threshold as well as cognitive dysfunction. Here, we tested whether sitagliptin (SITA), by virtue of its neuroprotective properties, could alleviate both epilepsy and associated cognitive dysfunction in a rat model of kindling epilepsy. Chemical kindling was induced by subconvulsive doses of pentylenetetrazol (PTZ) (30 mg/kg; i.p). SITA (50 mg/kg; p.o) was administered 1 h before PTZ injections. SITA conceivably attenuated PTZ hippocampal histological insult, preserved neuronal integrity and amended neurotransmitter perturbations in rat hippocampi paralleled with enhanced hippocampal GLP-1 levels as well as the downstream cAMP content and protein kinase A (PKA) activity. Moreover, SITA improved cognitive functioning of rats in the Morris water maze which was coupled with hampered hippocampal p(Ser⁴⁰⁴)-tau and β-amyloid proteins. SITA replenished p(Ser⁹)-glycogen synthase kinase-3β (GSK-3β). It also opposed the boosted matrix metalloproteinase-9 (MMP-9), brain-derived neurotrophic factor (BDNF), and insulin-like growth factor-1 (IGF-1) levels associated with PTZ administration along with mitigation of both β-secretase-1 (BACE1) immunoreactivity and receptor for advanced glycation end products (RAGE) protein level in rat hippocampi. In conclusion, SITA subdues epileptic and cognitive upshots of PTZ kindling in rats, which might correspond to the modulation of BACE1, amyloidogenic/RAGE axis as well as GSK-3β/MMP-9/BDNF signaling cascade. SITA effects are probably mediated via boosting GLP-1 and subsequently enhancing GLP-1/GLP-1R signaling.

Expression Analysis of lncRNAs in Refractory and Non-Refractory Epileptic Patients

Long non-coding RNAs (lncRNAs) have been demonstrated to be involved in the pathogenesis of neuropsychiatric disorders such as epilepsy. In the current study, we evaluated expression of eight lncRNAs in 80 epileptic patients (40 refractory and 40 non-refractory ones) and 40 normal individual using quantitative real-time PCR. Bayesian regression model showed significant higher expression of UCA1 in both refractory and non-refractory groups compared with controls (posterior beta of relative expression (RE) = 2.03, P value = 0.003, and posterior beta of RE = 4.05, P value < 0.0001, respectively). Besides, expression of UCA1 was higher in non-refractory patients compared with refractory ones (posterior beta of RE = 2.008, P value = 0.019). When repeating statistical analyses in a gender-based manner, differences in expression of UCA1 were significant in all subgroup analyses except for male non-refractory vs. refractory subgroups analysis. Expression levels of NKILA and ANRIL were higher in both refractory and non-refractory groups compared with controls (posterior beta of RE = 1.565, P value = 0.018, and posterior beta of RE = 1.902, P value = 0.006 for NKILA; posterior beta of RE = 1.304, P value < 0.0001, and posterior beta of RE = 1.603, P value = 0.019 for ANRIL, respectively). However, expression levels of these two lncRNAs were not different between refractory and non-refractory groups. Gender-based analysis for these two lncRNAs revealed similar results except for lack of difference in ANRIL expression between male refractory group and controls. Expression of THRIL was significantly lower in both refractory and non-refractory groups compared with controls (posterior beta of RE = - 0.842, P value = 0.044 and posterior beta of RE = - 1.969, P value < 0.0001, respectively). Furthermore, expression of this lncRNA was lower in non-refractory patients compared with refractory ones (posterior beta of RE = - 1.129, P value = 0.002). However, no significant difference was detected between non-refractory and refractory patients either in males or females. The interactions between gender and relative expressions of PACER, DILC, and MALAT1 were significant, so the results were assessed in gender-based manner. In females, expression of DILC was higher in non-refractory patients compared with refractory ones (posterior beta of RE = 0.959, P value = 0.044). Expression of MALAT1 was lower in female non-refractory patients compared with controls and in female non-refractory patients compared with refractory ones (posterior beta of RE = - 1.35, P value = 0.002, and posterior beta of RE = - 0.942, P value = 0.045, respectively). Finally, expression of PACER was higher in refractory patients vs. controls and non-refractory patients vs. controls in both male and female subgroups. However, comparison between non-refractory and refractory patients revealed significant results only among females. Expression of none of the assessed lncRNAs was correlated with age of study participants. There were robust correlations between expression levels of lncRNAs. The most robust correlations were detected between UCA1 and PACER (r = 0.84, P < 0.0001) and between UCA1 and ANRIL (r = 0.75, P < 0.0001). Taken together, our study demonstrated dysregulation of lncRNAs in peripheral blood of epileptic patients and potentiated them as biomarkers for this neurologic condition.

The Potential Markers of Circulating microRNAs and long non-coding RNAs in Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder and one of the leading causes of disability and mortality in the late life with no curative treatment currently. Thus, it is urgently to establish sensitive and non-invasive biomarkers for AD diagnosis, particularly in the early stage. Recently, emerging number of microRNAs (miRNAs) and long-noncoding RNAs (lncRNAs) are considered as effective biomarkers in various diseases as they possess characteristics of stable, resistant to RNAase digestion and many extreme conditions in circulatory fluid. This review highlights recent advances in the identification of the aberrantly expressed miRNAs and lncRNAs in circulatory network for detection of AD. We summarized the abnormal expressed miRNAs in blood and cerebrospinal fluid (CSF), and detailed discussed the functions and molecular mechanism of serum or plasma miRNAs-miR-195, miR-155, miR-34a, miR-9, miR-206, miR-125b and miR-29 in the regulation of AD progression. In addition, we also elaborated the role of circulating lncRNA major including beta-site APP cleaving enzyme 1 (BACE1) and its antisense lncRNA BACE1-AS in AD pathological advancement. In brief, confirming the aberrantly expressed circulating miRNAs and lncRNAs will provide an effective testing tools for treatment of AD in the future.

Long non-coding RNAs: Diverse roles in various disorders

BACKGROUND

Long non-coding RNAs (lncRNAs) are a group of transcripts larger than 200 nucleotides that are not translated to proteins. These transcripts regulate expression of numerous genes at different levels by acting as decoys, scaffolds, and enhancers. Thus they regulate cell development, differentiation and fate.

OBJECTIVE

To find the role of lncRNAs in various diseases.

METHODS

We searched PubMed and google scholar and summarized the data regarding the role of lncRNAs in cancer and neurologic disorders.

RESULTS

Several recent studies have shown that their expressions are up-/down-regulated in malignant tissues. Consequently, they have suggested that lncRNAs can differentiate cancer samples from normal samples. Their application as biomarker is not limited to cancers. In several neurologic or psychiatric disorders researchers have found aberrant expression of lncRNAs.

CONCLUSIONS

Taken together, lncRNAs constitute a novel vast area of research to find answer to fundamental biologic questions.

Expression analysis of GRIN2B, BDNF, and IL-1β genes in the whole blood of epileptic patients

Epilepsy is a brain disorder with a global prevalence of 1%. It has been attributed to genetics and environmental factors. Despite efforts to identify the molecular pathology of epilepsy, the underlying mechanism is not understood yet. This study was carried out to compare GRIN2B, BDNF, and IL-1β gene expressions in 50 patients suffering from generalized epilepsy with tonic-colonic seizures and 50 age- and sex-matched healthy subjects using TaqMan Real-time PCR. Our results demonstrated significant upregulation of these genes in people with epilepsy compared with healthy subjects. We also found a positive correlation between GRIN2B and BDNF expression (r²=0.4619, p < 0.0001), BDNF and IL-1β expression (r² = 0.515, p < 0.0001), and GRIN2B and IL-1β gene expressions (r² = 0.666, p < 0.0001) which implies the possibility to estimate the expression level of these genes by assessment of expression of one of them. Considering the results of the previous animal studies which showed upregulation of these genes in brain tissues of epileptic animals, the expression levels of GRIN2B, BDNF, and IL-1β in blood samples might be related to their expression in brain samples. Future studies are needed to assess the role of these genes in the pathogenesis of epilepsy and evaluate whether altered expression of these genes along with imaging methods can facilitate subtyping the epilepsy.