The Role of MicroRNAs in Patients with Amyotrophic Lateral Sclerosis

Engineered smart materials for RNA based molecular therapy to treat Glioblastoma

Glioblastoma (GBM) is an aggressive malignancy of the central nervous system (CNS) that remains incurable despite the multitude of improvements in cancer therapeutics. The conventional chemo and radiotherapy post-surgery have only been able to improve the prognosis slightly; however, the development of resistance and/or tumor recurrence is almost inevitable. There is a pressing need for adjuvant molecular therapies that can successfully and efficiently block tumor progression. During the last few decades, non-coding RNAs (ncRNAs) have emerged as key players in regulating various hallmarks of cancer including that of GBM. The levels of many ncRNAs are dysregulated in cancer, and ectopic modulation of their levels by delivering antagonists or overexpression constructs could serve as an attractive option for cancer therapy. The therapeutic potential of several types of ncRNAs, including miRNAs, lncRNAs, and circRNAs, has been validated in both in vitro and in vivo models of GBM. However, the delivery of these RNA-based therapeutics is highly challenging, especially to the tumors of the brain as the blood-brain barrier (BBB) poses as a major obstacle, among others. Also, since RNA is extremely fragile in nature, careful considerations must be met while designing a delivery agent. In this review we have shed light on how ncRNA therapy can overcome the limitations of its predecessor conventional therapy with an emphasis on smart nanomaterials that can aide in the safe and targeted delivery of nucleic acids to treat GBM. Additionally, critical gaps that currently exist for successful transition from viral to non-viral vector delivery systems have been identified. Finally, we have provided a perspective on the future directions, potential pathways, and target areas for achieving rapid clinical translation of, RNA-based macromolecular therapy to advance the effective treatment of GBM and other related diseases.

Differential Expression of miRNAs in Amyotrophic Lateral Sclerosis Patients

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease that affects nerve cells in the brain and spinal cord, causing loss of muscle control, muscle atrophy and in later stages, death. Diagnosis has an average delay of 1 year after symptoms onset, which impairs early management. The identification of a specific disease biomarker could help decrease the diagnostic delay. MicroRNA (miRNA) expression levels have been proposed as ALS biomarkers, and altered function has been reported in ALS pathogenesis. The aim of this study was to assess the differential expression of plasma miRNAs in ALS patients and two control populations (healthy controls and ALS-mimic disorders). For that, 16 samples from each group were pooled, and then 1008 miRNAs were assessed through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). From these, ten candidate miRNAs were selected and validated in 35 ALS patients, 16 ALS-mimic disorders controls and 15 healthy controls. We also assessed the same miRNAs in two different time points of disease progression. Although we were unable to determine a miRNA signature to use as disease or condition marker, we found that miR-7-2-3p, miR-26a-1-3p, miR-224-5p and miR-206 are good study candidates to understand the pathophysiology of ALS.

Biomarkers in Duchenne Muscular Dystrophy: Current Status and Future Directions

 Duchenne muscular dystrophy is a severe, X-linked disease characterized by decreased muscle mass and function in children. Genetic and biochemical research over the years has led to the characterization of the cause and the pathophysiology of the disease. Moreover, the elucidation of genetic mechanisms underlining Duchenne muscular dystrophy has allowed for the design of innovative personalized therapies.The identification of specific, accurate, and sensitive biomarkers is becoming crucial for evaluating muscle disease progression and response to therapies, disease monitoring, and the acceleration of drug development and related regulatory processes.This review illustrated the up-to-date progress in the development of candidate biomarkers in DMD at the level of proteins, metabolites, micro-RNAs (miRNAs) and genetic modifiers also highlighting the complexity of translating research results to clinical practice.We highlighted the challenges encountered in translating biomarkers into the clinical context and the existing bottlenecks hampering the adoption of biomarkers as surrogate endpoints. These challenges could be overcome by national and international collaborative efforts, multicenter data sharing, definition of public biobanks and patients' registries, and creation of large cohorts of patients. Novel statistical tools/ models suitable to analyze small patient numbers are also required.Finally, collaborations with pharmaceutical companies would greatly benefit biomarker discovery and their translation in clinical trials.

Recent Advances in the Roles of MicroRNA and MicroRNA-Based Diagnosis in Neurodegenerative Diseases

Neurodegenerative diseases manifest as progressive loss of neuronal structures and their myelin sheaths and lead to substantial morbidity and mortality, especially in the elderly. Despite extensive research, there are few effective treatment options for the diseases. MicroRNAs have been shown to be involved in the developmental processes of the central nervous system. Mounting evidence suggest they play an important role in the development of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. However, there are few reviews regarding the roles of miRNAs in neurodegenerative diseases. This review summarizes the recent developments in the roles of microRNAs in neurodegenerative diseases and presents the application of microRNA-based methods in the early diagnosis of these diseases.

Dysregulated miRNAs as Biomarkers and Therapeutical Targets in Neurodegenerative Diseases

Alzheimer’s disease (AD), Parkinson’s disease (PD), and Amyotrophic Lateral Sclerosis (ALS) are representative neurodegenerative diseases (NDs) characterized by degeneration of selective neurons, as well as the lack of effective biomarkers and therapeutic treatments. In the last decade, microRNAs (miRNAs) have gained considerable interest in diagnostics and therapy of NDs, owing to their aberrant expression and their ability to target multiple molecules and pathways. Here, we provide an overview of dysregulated miRNAs in fluids (blood or cerebrospinal fluid) and nervous tissue of AD, PD, and ALS patients. By emphasizing those that are commonly dysregulated in these NDs, we highlight their potential role as biomarkers or therapeutical targets and describe the use of antisense oligonucleotides as miRNA therapies.

miRNAs: A potentially valuable tool in pesticide toxicology assessment-current experimental and epidemiological data review

miRNAs are responsible for the regulation of many cellular processes such as development, cell differentiation, proliferation, apoptosis, and tumor growth. Several studies showed that they can also serve as specific, stable, and sensitive markers of chemical exposure. In this review, current experimental and epidemiological data evidencing deregulation in miRNA expression in response to fungicides, insecticides or herbicides were analyzed. As shown by Venn's diagrams, miR-363 and miR-9 deregulation is associated with fungicide exposure in vitro and in vivo, while let-7, miR-155, miR-181 and miR-21 were found to be commonly deregulated by at least three different insecticides. Furthermore, let-7, miR-30, miR-126, miR-181 and miR-320 were commonly deregulated by 3 different herbicides. Notably, these 5 miRNAs were also found to be deregulated by one or more insecticides, suggesting their participation in the cellular response to pesticides, regardless of their chemical structure. All these miRNAs have been proposed as potential biomarkers for fungicide, insecticide, or herbicide exposure. These results allow us to improve our understanding of the molecular mechanisms of toxicity upon pesticide exposure, although further studies are needed to confirm these miRNAs as definitive (not potential) biomarkers of pesticide exposure.

Circulating small RNA signatures differentiate accurately the subtypes of muscular dystrophies: small-RNA next-generation sequencing analytics and functional insights

Muscular dystrophies are a group of rare and severe inherited disorders mainly affecting the muscle tissue. Duchene Muscular Dystrophy, Myotonic Dystrophy types 1 and 2, Limb Girdle Muscular Dystrophy and Facioscapulohumeral Muscular Dystrophy are some of the members of this family of disorders. In addition to the current diagnostic tools, there is an increasing interest for the development of novel non-invasive biomarkers for the diagnosis and monitoring of these diseases. miRNAs are small RNA molecules characterized by high stability in blood thus making them ideal biomarker candidates for various diseases. In this study, we present the first genome-wide next-generation small RNA sequencing in serum samples of five different types of muscular dystrophy patients and healthy individuals. We identified many small RNAs including miRNAs, lncRNAs, tRNAs, snoRNAs and snRNAs, that differentially discriminate the muscular dystrophy patients from the healthy individuals. Further analysis of the identified miRNAs showed that some miRNAs can distinguish the muscular dystrophy patients from controls and other miRNAs are specific to the type of muscular dystrophy. Bioinformatics analysis of the target genes for the most significant miRNAs and the biological role of these genes revealed different pathways that the dysregulated miRNAs are involved in each type of muscular dystrophy investigated. In conclusion, this study shows unique signatures of small RNAs circulating in five types of muscular dystrophy patients and provides a useful resource for future studies for the development of miRNA biomarkers in muscular dystrophies and for their involvement in the pathogenesis of the disorders.

Insights into the identification of a molecular signature for amyotrophic lateral sclerosis exploiting integrated microRNA profiling of iPSC-derived motor neurons and exosomes

Amyotrophic lateral sclerosis (ALS) is a rare neurodegenerative disorder characterized by progressive degeneration of motor neurons (MNs). Most cases are sporadic, whereas 10% are familial. The pathological mechanisms underlying the disease are partially understood, but it is increasingly being recognized that alterations in RNA metabolism and deregulation of microRNA (miRNA) expression occur in ALS. In this study, we performed miRNA expression profile analysis of iPSC-derived MNs and related exosomes from familial patients and healthy subjects. We identified dysregulation of miR-34a, miR-335 and miR-625-3p expression in both MNs and exosomes. These miRNAs regulate genes and pathways which correlate with disease pathogenesis, suggesting that studying miRNAs deregulation can contribute to deeply investigate the molecular mechanisms underlying the disease. We also assayed the expression profile of these miRNAs in the cerebrospinal fluid (CSF) of familial (fALS) and sporadic patients (sALS) and we identified a significant dysregulation of miR-34a-3p and miR-625-3p levels in ALS compared to controls. Taken together, all these findings suggest that miRNA analysis simultaneously performed in different human biological samples could represent a promising molecular tool to understand the etiopathogenesis of ALS and to develop new potential miRNA-based strategies in this new propitious therapeutic era.

Lack of an association between SCFD1 rs10139154 polymorphism and amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease. Through a genome‑wide association study (GWAS), the Sec1 family domain‑containing protein 1 (SCFD1) rs10139154 variant at 14q12 has emerged as a risk factor gene for ALS. Moreover, it has been reported to influence the age at onset (AAO) of patients with ALS. The aim of the present study was to assess the association of the SCFD1 rs10139154 polymorphism with the risk of developing ALS. For this purpose, 155 patients with sporadic ALS and 155 healthy controls were genotyped for the SCFD1 rs10139154. The effect of the SCFD1 rs10139154 polymorphism was then examined on the following parameters: i) The risk of developing ALS; ii) the AAO of ALS; iii) the site of ALS onset (patients with bulbar onset ALS vs. healthy controls; and patients with limb onset ALS vs. healthy controls); and iv) the AAO of ALS onset with subgroup analyses based on the site of onset (bulbar and limb, crude and adjusted for sex). The analysis of all the outcomes was performed assuming five genetic models. Crude and adjusted analyses were applied. The threshold for statistical significance was set at 0.05. The results revealed no association between SCFD1 rs10139154 and any of the examined phenotypes in any of the models examined. On the whole, based on the findings of the present study, SCFD1 rs10139154 does not appear to play a determining role in the risk of developing ALS.

The Biogenesis of miRNAs and Their Role in the Development of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects upper and lower motor neurons. As there is no effective treatment for ALS, it is particularly important to screen key gene therapy targets. The identifications of microRNAs (miRNAs) have completely changed the traditional view of gene regulation. miRNAs are small noncoding single-stranded RNA molecules involved in the regulation of post-transcriptional gene expression. Recent advances also indicate that miRNAs are biomarkers in many diseases, including neurodegenerative diseases. In this review, we summarize recent advances regarding the mechanisms underlying the role of miRNAs in ALS pathogenesis and its application to gene therapy for ALS. The potential of miRNAs to target diverse pathways opens a new avenue for ALS therapy.

Identification of let-7f and miR-338 as plasma-based biomarkers for sporadic amyotrophic lateral sclerosis using meta-analysis and empirical validation

Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disease that in most cases occurs sporadic (sALS). The disease is not curable, and its pathogenesis mechanisms are not well understood yet. Given the intricacy of underlying molecular interactions and heterogeneity of ALS, the discovery of molecules contributing to disease onset and progression will open a new avenue for advancement in early diagnosis and therapeutic intervention. Here we conducted a meta-analysis of 12 circulating miRNA profiling studies using the robust rank aggregation (RRA) method, followed by enrichment analysis and experimental verification. We identified miR-451a and let-7f-5p as meta-signature miRNAs whose targets are involved in critical pathogenic pathways underlying ALS, including ‘FoxO signaling pathway’, ‘MAPK signaling pathway’, and ‘apoptosis’. A systematic review of 7 circulating gene profiling studies elucidated that 241 genes up-regulated in sALS circulation with concomitant being targets of the meta-signature miRNAs. Protein–protein interaction (PPI) network analysis of the candidate targets using MCODE algorithm revealed the main subcluster is involved in multiple cascades eventually leads apoptosis, including ‘positive regulation of neuron apoptosis. Besides, we validated the meta-analysis results using RT-qPCR. Indeed, relative expression analysis verified let-7f-5p and miR-338-3p as significantly down-regulated and up-regulated biomarkers in the plasma of sALS patients, respectively. Receiver operating characteristic (ROC) analysis also highlighted the let-7f-5p and miR-338-3p potential as robustness plasma biomarkers for diagnosis and potential therapeutic targets of sALS disease.

Neuromuscular Junction Dysfunction in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurological disorder characterized by progressive degeneration of motor neurons leading to skeletal muscle denervation. Earlier studies have shown that motor neuron degeneration begins in motor cortex and descends to the neuromuscular junction (NMJ) in a dying forward fashion. However, accumulating evidences support that ALS is a distal axonopathy where early pathological changes occur at the NMJ, prior to onset of clinical symptoms and propagates towards the motor neuron cell body supporting "dying back" hypothesis. Despite several evidences, series of events triggering NMJ disassembly in ALS are still obscure. Neuromuscular junction is a specialized tripartite chemical synapse which involves a well-coordinated communication among the presynaptic motor neuron, postsynaptic skeletal muscle, and terminal Schwann cells. This review provides comprehensive insight into the role of NMJ in ALS pathogenesis. We have emphasized the molecular alterations in cellular components of NMJ leading to loss of effective neuromuscular transmission in ALS. Further, we provide a preview into research involved in exploring NMJ as potential target for designing effective therapies for ALS.

Systems Biology to Address Unmet Medical Needs in Neurological Disorders

Neurological diseases are highly prevalent and constitute a significant cause of mortality and disability. Neurological disorders encompass a heterogeneous group of neurodegenerative conditions, broadly characterized by injury to the peripheral and/or central nervous system. Although the etiology of neurological diseases varies greatly, they share several characteristics, such as heterogeneity of clinical presentation, non-cell autonomous nature, and diversity of cellular, subcellular, and molecular pathways. Systems biology has emerged as a valuable platform for addressing the challenges of studying heterogeneous neurological diseases. Systems biology has manifold applications to address unmet medical needs for neurological illness, including integrating and correlating different large datasets covering the transcriptome, epigenome, proteome, and metabolome associated with a specific condition. This is particularly useful for disentangling the heterogeneity and complexity of neurological conditions. Hence, systems biology can help in uncovering pathophysiology to develop novel therapeutic targets and assessing the impact of known treatments on disease progression. Additionally, systems biology can identify early diagnostic biomarkers, to help diagnose neurological disease preceded by a long subclinical phase, as well as define the exposome, the collection of environmental toxicants that increase risk of certain neurological diseases. In addition to these current applications, there are numerous potential emergent uses, such as precision medicine.

Therapeutic application of rTMS in neurodegenerative and movement disorders: A review

Transcranial magnetic stimulation (TMS) is a non-invasive form of brain stimulation that makes use of the magnetic field generated when an electric current passes through a magnetic coil placed over the scalp. It can be applied as a single stimulus at a time, in pairs of stimuli, or repetitively in trains of stimuli (repetitive TMS, rTMS). RTMS can induce changes in brain activity, whose after-effects reflect the processes of long-term potentiation and long-term depression, as certain protocols, namely those using low frequencies (≤1 Hz) seem to suppress cortical excitability, while those using high frequencies (>1 Hz) seem to enhance it. It is a technique with very few and mostly mild side-effects, whose effects can persist for long time periods, and as such, it has been studied as a potential treatment option in a multitude of neurodegenerative diseases, including those affecting movement. Although rTMS has received approval as a treatment strategy of only a few aspects in movement disorders in the latest guidelines, its further use seems to also be promising in their context. In this review, we gathered the available literature on the therapeutic application of rTMS in movement disorders, namely Parkinson's disease, Amyotrophic Lateral Sclerosis, Huntington's disease, Dystonia, Tic disorders and Essential Tremor.

Exosomes in Ageing and Motor Neurone Disease: Biogenesis, Uptake Mechanisms, Modifications in Disease and Uses in the Development of Biomarkers and Therapeutics

Intercellular communication between neurons and their surrounding cells occurs through the secretion of soluble molecules or release of vesicles such as exosomes into the extracellular space, participating in brain homeostasis. Under neuro-degenerative conditions associated with ageing, such as amyotrophic lateral sclerosis (ALS), Alzheimer's or Parkinson's disease, exosomes are suspected to propagate toxic proteins. The topic of this review is the role of exosomes in ageing conditions and more specifically in ALS. Our current understanding of exosomes and exosome-related mechanisms is first summarized in a general sense, including their biogenesis and secretion, heterogeneity, cellular interaction and intracellular fate. Their role in the Central Nervous System (CNS) and ageing of the neuromotor system is then considered in the context of exosome-induced signaling. The review then focuses on exosomes in age-associated neurodegenerative disease. The role of exosomes in ALS is highlighted, and their use as potential biomarkers to diagnose and prognose ALS is presented. The therapeutic implications of exosomes for ALS are considered, whether as delivery vehicles, neurotoxic targets or as corrective drugs in and of themselves. A diverse set of mechanisms underpin the functional roles, both confirmed and potential, of exosomes, generally in ageing and specifically in motor neurone disease. Aspects of their contents, biogenesis, uptake and modifications offer many plausible routes towards the development of novel biomarkers and therapeutics.

The Emerging Role of Long Non-Coding RNAs and MicroRNAs in Neurodegenerative Diseases: A Perspective of Machine Learning

Neurodegenerative diseases (NDs) are characterized by progressive neuronal dysfunction and death of brain cells population. As the early manifestations of NDs are similar, their symptoms are difficult to distinguish, making the timely detection and discrimination of each neurodegenerative disorder a priority. Several investigations have revealed the importance of microRNAs and long non-coding RNAs in neurodevelopment, brain function, maturation, and neuronal activity, as well as its dysregulation involved in many types of neurological diseases. Therefore, the expression pattern of these molecules in the different NDs have gained significant attention to improve the diagnostic and treatment at earlier stages. In this sense, we gather the different microRNAs and long non-coding RNAs that have been reported as dysregulated in each disorder. Since there are a vast number of non-coding RNAs altered in NDs, some sort of synthesis, filtering and organization method should be applied to extract the most relevant information. Hence, machine learning is considered as an important tool for this purpose since it can classify expression profiles of non-coding RNAs between healthy and sick people. Therefore, we deepen in this branch of computer science, its different methods, and its meaningful application in the diagnosis of NDs from the dysregulated non-coding RNAs. In addition, we demonstrate the relevance of machine learning in NDs from the description of different investigations that showed an accuracy between 85% to 95% in the detection of the disease with this tool. All of these denote that artificial intelligence could be an excellent alternative to help the clinical diagnosis and facilitate the identification diseases in early stages based on non-coding RNAs.

Epigenetic dysregulation in various types of cells exposed to extremely low-frequency magnetic fields

Epigenetic mechanisms regulate gene expression, without changing the DNA sequence, and establish cell-type-specific temporal and spatial expression patterns. Alterations of epigenetic marks have been observed in several pathological conditions, including cancer and neurological disorders. Emerging evidence indicates that a variety of environmental factors may cause epigenetic alterations and eventually influence disease risks. Humans are increasingly exposed to extremely low-frequency magnetic fields (ELF-MFs), which in 2002 were classified as possible carcinogens by the International Agency for Research on Cancer. This review summarizes the current knowledge of the link between the exposure to ELF-MFs and epigenetic alterations in various cell types. In spite of the limited number of publications, available evidence indicates that ELF-MF exposure can be associated with epigenetic changes, including DNA methylation, modifications of histones and microRNA expression. Further research is needed to investigate the molecular mechanisms underlying the observed phenomena.

The Novel Regulatory Role of lncRNA-miRNA-mRNA Axis in Amyotrophic Lateral Sclerosis: An Integrated Bioinformatics Analysis

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease that primarily affects motor neurons, causing muscle atrophy, bulbar palsy, and pyramidal tract signs. However, the aetiology and pathogenesis of ALS have not been elucidated to date. In this study, a competitive endogenous RNA (ceRNA) network was constructed by analyzing the expression profiles of messenger RNAs (mRNAs) and long noncoding RNAs (lncRNAs) that were matched by 7 ALS samples and 4 control samples, and then a protein-protein interaction (PPI) network was constructed to identify the genes related to ALS. Gene Ontology (GO) was used to study the potential functions of differentially expressed mRNAs (DEmRNAs) in the ceRNA network. For the ALS and control groups, 247177 potential lncRNA-mRNA ceRNA relationship pairs were screened. Analysis of significant relationship pairs demonstrated that the PPI modules formed by the MALAT1-regulated SYNRG, ITSN2, PICALM, AP3B1, and AAK1 genes may play important roles in the pathogenesis of ALS, and these results may help to characterize the pathogenesis of ALS.

Lack of association between TREM2 rs75932628 variant and amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a multifactorial neurodegenerative disease. Inflammatory processes are among the mechanisms that are implicated in ALS pathogenesis. The TREM2 rs75932628 T variant may influence the regulatory effect of TREM2 on inflammation. Studies regarding the role of the rs75932628 variant in ALS have yielded inconsistent results, so far. To assess the role of TREM2 rs75932628 on ALS risk. We genotyped 155 patients with sporadic ALS and 155 healthy controls for TREM2 rs75932628. We also merged and meta-analyzed our data with data from previous studies (with a total of 7524 ALS cases and 14,675 controls), regarding TREM2 rs75932628 and ALS. No ALS or healthy subjects carried the TREM2 rs75932628-T variant. Results from meta-analyses (overall approach and sensitivity analyses) yielded no significant results for possible connection between TREM2 rs75932628-T variant and ALS. Based on our results, TREM2 rs75932628 does not seem to play a determining role to the pathophysiology of ALS.

MicroRNA-149 is downregulated in Alzheimer's disease and inhibits β-amyloid accumulation and ameliorates neuronal viability through targeting BACE1

Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) plays a critical role in Alzheimer's disease (AD) pathogenesis. This study aimed to investigate the relationship between microRNA-149 (miR-149) and BACE1, and evaluate the clinical significance and biological function of miR-149 in AD progression. Bioinformatics analysis and a luciferase reporter assay were used to confirm the interaction between miR-149 and BACE1. Expression of miR-149 and BACE1 was estimated using quantitative real-time PCR. The clinical significance of miR-149 in AD diagnosis and severity determination was evaluated using ROC analysis. The effect of miR-149 on Aβ accumulation and neuronal viability was analyzed in Aβ-treated SH-SY5Y cells. miR-149 was found directly binding the 3'-UTR of BACE1 and was negatively correlated with BACE1 in AD patients and cell model. Serum miR-149 expression was downregulated in AD patients and served as a potential diagnostic biomarker. The overexpression of miR-149 in Aβ-treated SH-SY5Y cells resulted in inhibited Aβ accumulation and enhanced neuronal viability. This study demonstrated that serum miR-149 is decreased in AD patients and serves as a candidate diagnostic biomarker, and that the overexpression of miR-149 may suppress Aβ accumulation and promote neuronal viability by targeting BACE1 in AD model cells.

Parkinson's disease and pesticides: Are microRNAs the missing link?

Parkinson's disease (PD) is a common neurodegenerative disorder that leads to significant morbidity and decline in the quality of life. It develops due to loss of dopaminergic neurons in the substantia nigra pars compacta, and among its pathogenic factors oxidative stress plays a critical role in disease progression. Pesticides are a broad class of chemicals widely used in agriculture and households for the protection of crops from insects and fungi. Several of them have been incriminated as risk factors for PD, but the underlying mechanisms have yet to be fully understood. MicroRNAs (miRNAs) are small, non-coding RNA molecules that play an important role in regulating mRNA translation and protein synthesis. miRNA levels have been shown to be affected in several diseases as well. Since the studies on the association between pesticides and PD have yet to reach definitive conclusions, here we review recent evidence on deregulated microRNAs upon pesticide exposure, and attempt to find an overlap between miRNAs deregulated in PD and pesticides, as a missing link between the two, and enhance future research in this direction.

The role of MiRNA-21 in gliomas: Hope for a novel therapeutic intervention?

Gliomas are the most common primary brain tumors in adults. They are generally very resistant to treatment and are therefore associated with negative outcomes. MicroRNAs (miRNAs) are small, non-coding RNA molecules that affect many cellular processes by regulating gene expression and, post-transcriptionally, the translation of mRNAs. MiRNA-21 has been consistently shown to be upregulated in glioma and research has shown that it is involved in a wide variety of biological pathways, promoting tumor cell survival and invasiveness. Furthermore, it has been implicated in resistance to treatment, both against chemotherapy and radiotherapy. In this review, we gathered the existent data on miRNA-21 and gliomas, in terms of its expression levels, association with grade and prognosis, the pathways it involves and its targets in glioma, and finally how it leads to treatment resistance. Furthermore, we discuss how this knowledge could be applied in clinical practice in the years to come. To our knowledge, this is the first review to assess in extent and depth the role of miRNA-21 in gliomas.

CYP1A2 rs762551 polymorphism and risk for amyotrophic lateral sclerosis

BACKGROUND

Genetic variability is considered to confer susceptibility to amyotrophic lateral sclerosis (ALS). Oxidative stress is a significant contributor to ALS-related neurodegeneration, and it is regulated by cytochromes P450 (CYPs), such as CYP1A2; these are responsible for the oxidative metabolism of both exogenous and endogenous substrates in the brain, subsequently impacting ALS. The function of CYP1A2 is largely affected by genetic variability; however, the impact of CYP1A2 polymorphisms in ALS remains underinvestigated.

OBJECTIVE

This study aims to examine the possible association of ALS with the CYP1A2 rs762551 polymorphism, which codes for the high inducibility form of the enzyme.

METHODS

One hundred and fifty-five patients with sporadic ALS and 155 healthy controls were genotyped for the CYP1A2 rs762551. Statistical testing for the association of CYP1A2 rs762551 with risk for ALS was performed using SNPstats.

RESULTS

The CYP1A2 rs762551 C allele was associated with a decreased risk of ALS development. In the subgroup analysis according to the ALS site of onset, an association between CYP1A2 rs762551 and limb and bulbar onset of ALS was shown. Cox proportional-hazard regression analyses revealed a significant effect of the CYP1A2 rs762551 on the age of onset of ALS.

CONCLUSIONS

Based on our results, a primarily potential link between the CYP1A2 rs762551 polymorphism and ALS risk could exist.

The New CIC Mutation Associates with Mental Retardation and Severity of Seizure in Turkish Child with a Rare Class I Glucose-6-Phosphate Dehydrogenase Deficiency

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive disease that causes acute or chronic hemolytic anemia and potentially leads to severe jaundice in response to oxidative agents. Capicua transcriptional repressor (CIC) is an important gene associated with mental retardation, autosomal dominant 45. Affiliated tissues including skin, brain, bone, and related phenotypes are intellectual disability and seizures. Clinical, biochemical, and whole exome analysis are carried out in a Turkish family. Mutation analysis of G6PD and CIC genes by Sanger sequencing in the whole family was carried out to reveal the effect of these mutations on the patient's clinical outcome. Here, we present the case of epilepsy in an 8-year-old child with a hemizygous variation in G6PD gene and heterozygous mutation in CIC gene, resulting in focal epileptiform activity and hypsarrhythmia in electroencephalography (EEG), seizures, psychomotor retardation, speech impairment, intellectual disability, developmental regression, and learning difficulties. Whole exome sequencing confirmed the diagnosis of X-linked increased susceptibility for hemolytic anemia due to G6PD deficiency and mental retardation type 45 due to CIC variant, which explained the development of epileptic seizures. Considering CIC variant and relevant relation with the severity and course of the disease, G6PD mutations sustained through the family are defined as hereditary. Our findings could represent the importance of variants found in G6PD as well as CIC genes linked to the severity of epilepsy, which was presumed based on the significant changes in protein configuration.

Genetic Risk Factors for Essential Tremor: A Review

Highlights

In the current review, we thoroughly reviewed 74 identified articles regarding genes and genetic loci that confer susceptibility to ET. Over 50 genes/genetic loci have been examined for possible association with ET, but consistent results failed to be reported raising the need for collaborative multiethnic studies.

Background:

Essential tremor (ET) is a common movement disorder, which is mainly characterized by bilateral tremor (postural and/or kinetic) in the upper limbs, with other parts of the body possibly involved. While the pathophysiology of ET is still unclear, there is accumulating evidence indicating that genetic variability may be heavily involved in ET pathogenesis. This review focuses on the role of genetic risk factors in ET susceptibility.

Methods:

The PubMed database was searched for articles written in English, for studies with humans with ET, controls without ET, and genetic variants. The terms “essential tremor” and “polymorphism” (as free words) were used during search. We also performed meta-analyses for the most examined genetic variants.

Results:

Seventy four articles concerning LINGO1, LINGO2, LINGO4, SLC1A2, STK32B, PPARGC1A, CTNNA3, DRD3, ALAD, VDR, HMOX1, HMOX2, LRRK1,LRRK2, GBA, SNCA, MAPT, FUS, CYPsIL17A, IL1B, NOS1, ADH1B, TREM2, RIT2, HNMT, MTHFR, PPP2R2B, GSTP1, PON1, GABA receptors and GABA transporter, HS1BP3, ADH2, hSKCa3 and CACNL1A4 genes, and ETM genetic loci were included in the current review. Results from meta-analyses revealed a marginal association for the STK32B rs10937625 and a marginal trend for association (in sensitivity analysis) for the LINGO1 rs9652490, with ET.

Discussion:

Quite a few variants have been examined for their possible association with ET. LINGO1 rs9652490 and STK32B rs10937625 appear to influence, to some extent, ET susceptibility. However, the conflicting results and the lack of replication for many candidate genes raise the need for collaborative multiethnic studies.

Cytoplasmic TDP43 Binds microRNAs: New Disease Targets in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal, and incurable neurodegenerative disease. Recent studies suggest that dysregulation of gene expression by microRNAs (miRNAs) may play an important role in ALS pathogenesis. The reversible nature of this dysregulation makes miRNAs attractive pharmacological targets and a potential therapeutic avenue. Under physiological conditions, miRNA biogenesis, which begins in the nucleus and includes further maturation in the cytoplasm, involves trans-activation response element DNA/RNA-binding protein of 43 kDa (TDP43). However, TDP43 mutations or stress trigger TDP43 mislocalization and inclusion formation, a hallmark of most ALS cases, that may lead to aberrant protein/miRNA interactions in the cytoplasm. Herein, we demonstrated that TDP43 exhibits differential binding affinity for select miRNAs, which prompted us to profile miRNAs that preferentially bind cytoplasmic TDP43. Using cellular models expressing TDP43 variants and miRNA profiling analyses, we identified differential levels of 65 cytoplasmic TDP43-associated miRNAs. Of these, approximately 30% exhibited levels that differed by more than 3-fold in the cytoplasmic TDP43 models relative to our control model. The hits included both novel miRNAs and miRNAs previously associated with ALS that potentially regulate several predicted genes and pathways that may be important for pathogenesis. Accordingly, these findings highlight specific miRNAs that may shed light on relevant disease pathways and could represent potential biomarkers and reversible treatment targets for ALS.

Organochlorine pesticide levels in Greek patients with Parkinson's disease

Background

Parkinson’s disease (PD) is a neurodegenerative disease, mostly presenting with characteristic motor symptoms. Organochlorines (OC) are a class of widely-used pesticides that have been included among the list of environmental factors incriminated in PD pathogenesis. However, most studies reporting this association are based on questionnaires, and few have reported exposure data.

Aim

To examine the relationship between OC blood concentrations and PD risk.

Methods

In the present study, we studied the concentrations of 8 OC compounds (hexachlorobenzene, heptachlor, hepachlor epoxide, c-chlordane, a-chlordane, p,p’-DDE, DDD, DDT) in 104 Greek PD patients and 110 healthy controls.

Results

All substances studied were present in at least one sample. The most frequently detected (above the level of quantification) pesticides were p,p’-DDE (n = 214, 100 % of both groups) and hexachlorobenzene, HCB (n = 189, cases 46.5 %, controls 53.5 %). Higher levels of DDE were detected among PD patients in comparison to controls by using logistic regression analysis to control for confounders [Odds Ratio, OR (95 % confidence interval, C.I.)]: 2.592,(1.29–5.21)], whilst lower levels of HCB were detect among PD patients [OR,95 %CI:0.176(0.09−0.35)].

Conclusions

Our data suggest that exposure to specific OCs is related to the risk of PD. Further studies, using real exposure data, are needed in order to confirm and extend these findings.

Toxic-Metal-Induced Alteration in miRNA Expression Profile as a Proposed Mechanism for Disease Development

Toxic metals are extensively found in the environment, households, and workplaces and contaminate food and drinking water. The crosstalk between environmental exposure to toxic metals and human diseases has been frequently described. The toxic mechanism of action was classically viewed as the ability to dysregulate the redox status, production of inflammatory mediators and alteration of mitochondrial function. Recently, growing evidence showed that heavy metals might exert their toxicity through microRNAs (miRNA)—short, single-stranded, noncoding molecules that function as positive/negative regulators of gene expression. Aberrant alteration of the endogenous miRNA has been directly implicated in various pathophysiological conditions and signaling pathways, consequently leading to different types of cancer and human diseases. Additionally, the gene-regulatory capacity of miRNAs is particularly valuable in the brain—a complex organ with neurons demonstrating a significant ability to adapt following environmental stimuli. Accordingly, dysregulated miRNAs identified in patients suffering from neurological diseases might serve as biomarkers for the earlier diagnosis and monitoring of disease progression. This review will greatly emphasize the effect of the toxic metals on human miRNA activities and how this contributes to progression of diseases such as cancer and neurodegenerative disorders (NDDs).

Functional roles and networks of non-coding RNAs in the pathogenesis of neurodegenerative diseases

Recent transcriptome analyses have revealed that noncoding RNAs (ncRNAs) are broadly expressed in mammalian cells and abundant in the CNS, with tissue and cell type-specific expression patterns. Moreover, ncRNAs have been found to intricately and dynamically regulate various signaling pathways in neurodegeneration. As such, some antisense transcripts and microRNAs are known to directly affect neurodegeneration in disease contexts. The functions of ncRNAs in pathogenesis are unique for each disorder, as are the pertinent networks of ncRNA/miRNA/mRNA that mediate these functions. Thus, further understanding of ncRNA biogenesis and effects might aid the discovery of diagnostic biomarkers or development of effective therapeutics for neurodegenerative disorders. Here, we review the ncRNAs that have so far been identified in major neurodegenerative disease etiology and the mechanisms that link ncRNAs with disease-specific phenotypes, such as HTT aggregation in HD, α-synuclein in PD, and Aβ plaques and hyperphosphorylated Tau in AD. We also summarize the known lncRNA/miRNA/mRNA networks that participate in neurodegenerative diseases, and we discuss ncRNA-related treatments shown to delay disease onset and prolong lifespan in rodent models.

Downregulation of miR-335-5P in Amyotrophic Lateral Sclerosis Can Contribute to Neuronal Mitochondrial Dysfunction and Apoptosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease for which the pathophysiological mechanisms of motor neuron loss are not precisely clarified. Environmental and epigenetic mechanisms such as microRNAs (miRNAs) could have a role in disease progression. We studied the expression pattern of miRNAs in ALS serum from 60 patients and 29 healthy controls. We also analyzed how deregulated miRNAs found in serum affected cellular pathways such as apoptosis, autophagy and mitochondrial physiology in SH-SY5Y cells. We found that miR-335-5p was downregulated in ALS serum. SH-SY5Y cells were transfected with a specific inhibitor of miR-335-5p and showed abnormal mitochondrial morphology, with an increment of reactive species of oxygen and superoxide dismutase activity. Pro-apoptotic caspases-3 and 7 also showed an increased activity in transfected cells. The downregulation of miR-335-5p, which has an effect on mitophagy, autophagy and apoptosis in SH-SY5Y neuronal cells could have a role in the motor neuron loss observed in ALS.

Combining feature selection and shape analysis uncovers precise rules for miRNA regulation in Huntington's disease mice

Background

MicroRNA (miRNA) regulation is associated with several diseases, including neurodegenerative diseases. Several approaches can be used for modeling miRNA regulation. However, their precision may be limited for analyzing multidimensional data. Here, we addressed this question by integrating shape analysis and feature selection into miRAMINT, a methodology that we used for analyzing multidimensional RNA-seq and proteomic data from a knock-in mouse model (Hdh mice) of Huntington’s disease (HD), a disease caused by CAG repeat expansion in huntingtin (htt). This dataset covers 6 CAG repeat alleles and 3 age points in the striatum and cortex of Hdh mice.

Results

Remarkably, compared to previous analyzes of this multidimensional dataset, the miRAMINT approach retained only 31 explanatory striatal miRNA-mRNA pairs that are precisely associated with the shape of CAG repeat dependence over time, among which 5 pairs with a strong change of target expression levels. Several of these pairs were previously associated with neuronal homeostasis or HD pathogenesis, or both. Such miRNA-mRNA pairs were not detected in cortex.

Conclusions

These data suggest that miRNA regulation has a limited global role in HD while providing accurately-selected miRNA-target pairs to study how the brain may compute molecular responses to HD over time. These data also provide a methodological framework for researchers to explore how shape analysis can enhance multidimensional data analytics in biology and disease.

Role of Nuclear Factor Kappa B (NF-κB) Signalling in Neurodegenerative Diseases: An Mechanistic Approach

A transcriptional regulatory nuclear factor kappa B (NF-κB) protein is a modulator of cellular biological activity via binding to a promoter region in the nucleus and transcribing various protein genes. The recent research implicated the intensive role of nuclear factor kappa B (NF-κB) in diseases like autoimmune disorder, inflammatory, cardiovascular and neurodegenerative diseases. Therefore, targeting the nuclear factor kappa B (NF-κB) protein offers a new opportunity as a therapeutic approach. Activation of IκB kinase/NF-κB signaling pathway leads to the development of various pathological conditions in human beings, such as neurodegenerative, inflammatory disorders, autoimmune diseases, and cancer. Therefore, the transcriptional activity of IκB kinase/NF- κB is strongly regulated at various cascade pathways. The nuclear factor NF-kB pathway plays a major role in the expression of pro-inflammatory genes, including cytokines, chemokines, and adhesion molecules. In response to the diverse stimuli, the cytosolic sequestered NF-κB in an inactivated form by binding with an inhibitor molecule protein (IkB) gets phosphorylated and translocated into the nucleus further transcribing various genes necessary for modifying various cellular functions. The various researches confirmed the role of different family member proteins of NF-κB implicated in expressing various genes products and mediating various cellular cascades. MicroRNAs, as regulators of NF- κB microRNAs play important roles in the regulation of the inflammatory process. Therefore, the inhibitor of NF-κB and its family members plays a novel therapeutic target in preventing various diseases. Regulation of NF- κB signaling pathway may be a safe and effective treatment strategy for various disorders.

miRNA Profiling for Early Detection and Treatment of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disorder caused by out of frame mutations in the dystrophin gene. The hallmark symptoms of the condition include progressive degeneration of skeletal muscle, cardiomyopathy, and respiratory dysfunction. The most recent advances in therapeutic strategies for the treatment of DMD involve exon skipping or administration of minidystrophin, but these strategies are not yet universally available, nor have they proven to be a definitive cure for all DMD patients. Early diagnosis and tracking of symptom progression of DMD usually relies on creatine kinase tests, evaluation of patient performance in various ambulatory assessments, and detection of dystrophin from muscle biopsies, which are invasive and painful for the patient. While the current research focuses primarily on restoring functional dystrophin, accurate and minimally invasive methods to detect and track both symptom progression and the success of early DMD treatments are not yet available. In recent years, several groups have identified miRNA signature changes in DMD tissue samples, and a number of promising studies consistently detected changes in circulating miRNAs in blood samples of DMD patients. These results could potentially lead to non-invasive detection methods, new molecular approaches to treating DMD symptoms, and new methods to monitor of the efficacy of the therapy. In this review, we focus on the role of circulating miRNAs in DMD and highlight their potential both as a biomarker in the early detection of disease and as a therapeutic target in the prevention and treatment of DMD symptoms.

Biological Significance of microRNA Biomarkers in ALS-Innocent Bystanders or Disease Culprits?

MicroRNAs (miRNAs) represent potential biomarkers for neurodegenerative disorders including amyotrophic lateral sclerosis (ALS). However, whether expression changes of individual miRNAs are simply an indication of cellular dysfunction and degeneration, or actually promote functional changes in target gene expression relevant to disease pathogenesis, is unclear. Here we used bioinformatics to test the hypothesis that ALS-associated miRNAs exert their effects through targeting genes implicated in disease etiology. We documented deregulated miRNAs identified in studies of ALS patients, noting variations in participants, tissue samples, miRNA detection or quantification methods used, and functional or bioinformatic assessments (if performed). Despite lack of experimental standardization, overlap of many deregulated miRNAs between studies was noted; however, direction of reported expression changes did not always concur. The use of in silico predictions of target genes for the most commonly deregulated miRNAs, cross-referenced to a selection of previously identified ALS genes, did not support our hypothesis. Specifically, although deregulated miRNAs were predicted to commonly target ALS genes, random miRNAs gave similar predictions. To further investigate biological patterns in the deregulated miRNAs, we grouped them by tissue source in which they were identified, indicating that for a core of frequently detected miRNAs, blood/plasma/serum may be useful for future profiling experiments. We conclude that in silico predictions of gene targets of deregulated ALS miRNAs, at least using currently available algorithms, are unlikely to be sufficient in informing disease pathomechanisms. We advocate experimental functional testing of candidate miRNAs and their predicted targets, propose miRNAs to prioritise, and suggest a concerted move towards protocol standardization for biomarker identification.

ERCC6L2 rs591486 polymorphism and risk for amyotrophic lateral sclerosis in Greek population

BACKGROUND

Α number of genetic variants have been associated with amyotrophic lateral sclerosis (ALS). A recent study supports that rs591486 across the ERCC6L2 gene and exposure to pesticides seem to have a joint effect on the development of Parkinson's disease, a disease which shares a few common characteristics with ALS.

OBJECTIVE

To detect a possible contribution of rs591486 ERCC6L2 to ALS.

METHODS

A total of 155 patients with ALS and 155 healthy controls were included in the study and genotyped for rs591486. Using logistic regression analyses (crude and adjusted for age and sex), rs591486 was tested for association with ALS risk. Subgroup analysis based on ALS site of onset was also performed. Cox regression analysis was applied in order for the effect of ERCC6L2 rs591486 on ALS age of onset to be tested.

RESULTS

Adjusted analysis showed that ERCC6L2 rs591486 was associated with an increased risk of ALS development, in dominant [odds ratio, OR (95% confidence interval, CI) 2.15 (1.04-4.46), p = 0.037] and over-dominant [OR (95%CI) = 1.91 (1.01-3.60), p = 0.043], modes. Subgroup analysis based on ALS site of onset revealed an association between ERCC6L2 rs591486 and ALS with limb onset. Results for Cox regression analysis indicated that G/A carriers had a lower age of ALS limb onset when compared to G/G carriers.

CONCLUSIONS

The current study provides preliminary indication for an implication of ERCC6L2 rs591486 in ALS development, as a possible genetic risk factor. These results possibly suggest that oxidative stress may be the main contributor in the pathophysiology of ALS.