MiR-214-3p attenuates cognition defects via the inhibition of autophagy in SAMP8 mouse model of sporadic Alzheimer's disease

NcRNAs: A synergistically antiapoptosis therapeutic tool in Alzheimer's disease

AIMS

The aim of this review is to systematically summarize and analyze the noncoding RNAs (ncRNAs), especially microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), in the cell apoptosis among Alzheimer's disease (AD) in recent years to demonstrate their value in the diagnosis and treatment of AD.

METHODS

We systematically summarized in vitro and in vivo studies focusing on the ncRNAs in the regulation of cell apoptosis among AD in PubMed, ScienceDirect, and Google Scholar.

RESULTS

We discover three patterns of ncRNAs (including 'miRNA-mRNA', 'lncRNA-miRNA-mRNA', and 'circRNA-miRNA-mRNA') form the ncRNA-based regulatory networks in regulating cell apoptosis in AD.

CONCLUSIONS

This review provides a future diagnosis and treatment strategy for AD patients based on ncRNAs.

The Potential of Targeting Autophagy-Related Non-coding RNAs in the Treatment of Alzheimer's and Parkinson's Diseases

Clearance of accumulated protein aggregates is one of the functions of autophagy. Recently, a clearer understanding of non-coding RNAs (ncRNAs) functions documented that ncRNAs have important roles in several biological processes associated with the development and progression of neurodegenerative disorders. Subtypes of ncRNA, including microRNA (miRNA), long noncoding RNA (lncRNA), and circular RNA (circRNA), are commonly dysregulated in neurodegenerative disorders such as Alzheimer and Parkinson diseases. Dysregulation of these non-coding RNAs has been associated with inhibition or stimulation of autophagy. Decreased miR-124 led to decreased/increased autophagy in experimental model of Alzheimer and Parkinson diseases. Increased BACE1-AS showed enhanced autophagy in Alzheimer disease by targeting miR-214-3p, Beclin-1, LC3-I/LC3-II, p62, and ATG5. A significant increase in NEAT1led to stimulated autophagy in experimental model of PD by targeting PINK1, LC3-I, LC3-II, p62 and miR-374c-5p. In addition, increased BDNF-AS and SNHG1 decreased autophagy in MPTP-induced PD by targeting miR-125b-5p and miR-221/222, respectively. The upregulation of circNF1-419 and circSAMD4A resulted in an increased autophagy by regulating Dynamin-1 and miR-29c 3p, respectively. A detailed discussion of miRNAs, circRNAs, and lncRNAs in relation to their autophagy-related signaling pathways is presented in this study.

Exosomes from Hypoxia-treated Mesenchymal Stem Cells: Promoting Neuroprotection in Ischemic Stroke Through miR-214-3p/PTEN Mechanism

Stroke stands as the second leading cause of death globally, surpassed only by ischemic heart disease. It accounts for 9% of total worldwide deaths. Given the swiftly evolving landscape, medical professionals and researchers are devoting increased attention to identifying more effective and safer treatments. Recent years have witnessed a focus on exosomes derived from mesenchymal stem cells cultivated under hypoxic conditions, referred to as Hypo-Exo. These specialized exosomes contain an abundance of components that facilitate the restoration of ischemic tissue, surpassing the content found in normal exosomes. Despite advancements, the precise role of Hypo-Exo in cases of cerebral ischemia remains enigmatic. Therefore, this study was designed to shed light on the potential efficacy of Hypo-Exo in stroke treatment. Our investigations unveiled promising outcomes, as the administration of Hypo-Exo led to improved behavioral deficits and reduced infarct areas in mice affected by ischemic conditions. Notably, these positive effects were hindered when Hypo-Exo loaded with anti-miR-214-3p were introduced, implying that the neuroprotective attributes of Hypo-Exo are reliant on miR-214-3p. This conclusion was substantiated by the high levels of miR-214-3p detected within Hypo-Exo. Furthermore, our examination of the ischemic penumbra zone revealed a gradual and sustained escalation in PTEN expression, a phenomenon effectively countered by Hypo-Exo treatment. Collectively, our findings suggest the existence of a regulatory pathway centered on miR-214-3p within Hypo-Exo. This pathway exerts a downregulating influence on the PTEN/Akt signaling pathway, thereby contributing to the amelioration of neurological function subsequent to ischemia-reperfusion events.

MicroRNAs dysregulated in multiple sclerosis affect the differentiation of CG-4 cells, an oligodendrocyte progenitor cell line

Introduction

Demyelination is one of the hallmarks of multiple sclerosis (MS). While remyelination occurs during the disease, it is incomplete from the start and strongly decreases with its progression, mainly due to the harm to oligodendrocyte progenitor cells (OPCs), causing irreversible neurological deficits and contributing to neurodegeneration. Therapeutic strategies promoting remyelination are still very preliminary and lacking within the current treatment panel for MS.

Methods

In a previous study, we identified 21 microRNAs dysregulated mostly in the CSF of relapsing and/or remitting MS patients. In this study we transfected the mimics/inhibitors of several of these microRNAs separately in an OPC cell line, called CG-4. We aimed (1) to phenotypically characterize their effect on OPC differentiation and (2) to identify corroborating potential mRNA targets via immunocytochemistry, RT-qPCR analysis, RNA sequencing, and Gene Ontology enrichment analysis.

Results

We observed that the majority of 13 transfected microRNA mimics decreased the differentiation of CG-4 cells. We demonstrate, by RNA sequencing and independent RT-qPCR analyses, that miR-33-3p, miR-34c-5p, and miR-124-5p arrest OPC differentiation at a late progenitor stage and miR-145-5p at a premyelinating stage as evidenced by the downregulation of premyelinating oligodendrocyte (OL) [Tcf7l2, Cnp (except for miR-145-5p)] and mature OL (Plp1, Mbp, and Mobp) markers, whereas only miR-214-3p promotes OPC differentiation. We further propose a comprehensive exploration of their change in cell fate through Gene Ontology enrichment analysis. We finally confirm by RT-qPCR analyses the downregulation of several predicted mRNA targets for each microRNA that possibly support their effect on OPC differentiation by very distinctive mechanisms, of which some are still unexplored in OPC/OL physiology.

Conclusion

miR-33-3p, miR-34c-5p, and miR-124-5p arrest OPC differentiation at a late progenitor stage and miR-145-5p at a premyelinating stage, whereas miR-214-3p promotes the differentiation of CG-4 cells. We propose several potential mRNA targets and hypothetical mechanisms by which each microRNA exerts its effect. We hereby open new perspectives in the research on OPC differentiation and the pathophysiology of demyelination/remyelination, and possibly even in the search for new remyelinating therapeutic strategies in the scope of MS.

Unraveling the role of miRNAs in the diagnosis, progression, and therapeutic intervention of Alzheimer's disease

Alzheimer's disease (AD) is a multifaceted, advancing neurodegenerative illness that is responsible for most cases of neurological impairment and dementia in the aged population. As the disease progresses, affected individuals may experience cognitive decline, linguistic problems, affective instability, and behavioral changes. The intricate nature of AD reflects the altered molecular mechanisms participating in the affected human brain. MicroRNAs (miRNAs, miR) are essential for the intricate control of gene expression in neurobiology. miRNAs exert their influence by modulating the transcriptome of brain cells, which typically exhibit substantial genetic activity, encompassing gene transcription and mRNA production. Presently, comprehensive studies are being conducted on AD to identify miRNA-based signatures that are indicative of the disease pathophysiology. These findings can contribute to the advancement of our understanding of the mechanisms underlying this disorder and can inform the development of therapeutic interventions based on miRNA and related RNA molecules. Therefore, this comprehensive review provides a detailed holistic analysis of the latest advances discussing the emerging role of miRNAs in the progression of AD and their possible application as potential biomarkers and targets for therapeutic interventions in future studies.

Autophagy as an Anti-senescent in Aging Neurocytes

Neuron homeostasis is crucial for the organism, and its maintenance is multifactorial, including autophagy. The turnover of aberrant intracellular components is a fundamental pathogenetic mechanism for cell aging. Autophagy is involved in the acceleration of the neurocyte aging process and the modification of cell longevity. Neurocyte aging is a process of loss of cell identity through cellular and subcellular changes that include molecular loss of epigenetics, transcriptomic, proteomic, and autophagy dysfunction. Autophagy dysfunction is the hallmark of neurocyte aging. Cell aging is the credential feature of neurodegenerative diseases. Pathophysiologically, aged neurocytes are characterized by dysregulated autophagy and subsequently neurocyte metabolic stress, resulting in accelerated neurocyte aging. In particular, chaperone- mediated autophagy perturbation results in upregulated expression of aging and apoptosis genes. Aged neurocytes are also characterized by the down-regulation of autophagy-related genes, such as ATG5-ATG12, LC3-II / LC3-I ratio, Beclin-1, and p62. Slowing aging through autophagy targeting is sufficient to improve prognosis in neurodegenerative diseases. Three primary anti-senescent molecules are involved in the aging process: mTOR, AMPK, and Sirtuins. Autophagy therapeutic effects can be applied to reverse and slow aging. This article discusses current advances in the role of autophagy in neurocyte homeostasis, aging, and potential therapeutic strategies to reduce aging and increase cell longevity.

A Comprehensive Review on the Importance of MiRNA-206 in the Animal Model and Human Diseases

MicroRNA-206 (miR-206) is a microRNA that is involved in many human diseases, such as myasthenia gravis, osteoarthritis, depression, cancers, etc. Both inhibition effects and progression roles of miR-206 have been reported for the past few years. High expression of miR-206 was observed in patients with osteoarthritis, gastric cancer and epithelial ovarian cancer compared to normal people. The study also showed that miR-206 promotes cancer progression in breast cancer patients and avascular necrosis of the femoral head. Meanwhile, several studies have shown that expression levels of miR-206 were down-regulated in laryngeal carcinoma cell multiplication, as well as in hepatocellular carcinoma, non-small lung cancer and infantile hemangioma. Moreover, miR-206 was up-regulated in the mild stage of amyotrophic lateral sclerosis patients and then down-regulated in the moderate and severe stages, indicating that miR-206 has the double effects of starting and aggravating the disease. In neuropsychiatric disorders, such as depression, miR-206 also plays an important role in the progression of the disease; the level of miR-206 is most highly expressed in the brains of patients with depression. In the current review, we summarize the role of miR-206 in various diseases, and miR-206 may be developed as a new biomarker for diagnosing diseases in the near future.

Epigenetics of Alzheimer’s Disease: Past, Present and Future

Alzheimer’s disease (AD) exemplifies a looming epidemic lacking effective treatment and manifests with the accumulation of neurofibrillary tangles, amyloid-β plaques, neuroinflammation, behavioral changes, and acute cognitive impairments. It is a complex, multifactorial disorder that arises from the intricate interaction between environment and genetic factors, restrained via epigenetic machinery. Though the research progress has improved the understanding of clinical manifestations and disease advancement, the causal mechanism of detrimental consequences remains undefined. Despite the substantial improvement in recent diagnostic modalities, it is challenging to distinguish AD from other forms of dementia. Accurate diagnosis is a major glitch in AD as it banks on the symptoms and clinical criteria. Several studies are underway in exploring novel and reliable biomarkers for AD. In this direction, epigenetic alterations have transpired as key modulators in AD pathogenesis with the impeding inferences for the management of this neurological disorder. The present chapter aims to discuss the significance of epigenetic modifications reported in the pathophysiology of AD such as DNA methylation, hydroxy-methylation, methylation of mtDNA, histone modifications, and noncoding RNAs. Additionally, the chapter also describes the possible therapeutic avenues that target epigenetic modifications in AD.

Non-Coding RNAs and Neurodegenerative Diseases: Information of their Roles in Apoptosis

Apoptosis can be known as a key factor in the pathogenesis of neurodegenerative disorders. In disease conditions, the rate of apoptosis expands and tissue damage may become apparent. Recently, the scientific studies of the non-coding RNAs (ncRNAs) has provided new information of the molecular mechanisms that contribute to neurodegenerative disorders. Numerous reports have documented that ncRNAs have important contributions to several biological processes associated with the increase of neurodegenerative disorders. In addition, microRNAs (miRNAs), circular RNAs (circRNAs), as well as, long ncRNAs (lncRNAs) represent ncRNAs subtypes with the usual dysregulation in neurodegenerative disorders. Dysregulating ncRNAs has been associated with inhibiting or stimulating apoptosis in neurodegenerative disorders. Therefore, this review highlighted several ncRNAs linked to apoptosis in neurodegenerative disorders. CircRNAs, lncRNAs, and miRNAs were also illustrated completely regarding the respective signaling pathways of apoptosis.

Up-regulating microRNA-214-3p relieves hypoxic-ischemic brain damage through inhibiting TXNIP expression

A list of microRNAs (miRs) has been referred to involve in the development of hypoxic-ischemic brain damage (HIBD). Based on that, we probed the concrete role of miR-214-3p regulating thioredoxin-interacting protein (TXNIP) in the illness. A neonatal HIBD mouse model was established using the Rice-Vannucci method, followed by measurements of miR-214-3p and TXNIP levels in brain tissues. After modeling, mice were given brain injection of the compounds that could alter miR-214-3p and TXNIP expression. Afterward, neurological function, neuronal inflammation, neuronal apoptosis, neuron morphology, and the number of Nissl body were assessed in HIBD mice. The binding of miR-214-3p to TXNIP was analyzed. Lower miR-214-3p and higher TXNIP were analyzed in brain tissues of mice with HIBD. Up-regulating miR-214-3p or depleting TXNIP improved neurological function, reduced neuronal inflammation and neuronal apoptosis, attenuated morphological damage of neurons, and increased the number of Nissl bodies in mice with HIBD. TXNIP was targeted by miR-214-3p and overexpressing TXNIP reversed the therapeutic effect of miR-214-3p on HIBD mice. It is noted that promotion of miR-214-3p relieves HIBD in mice through inhibiting TXNIP expression.

Role of MicroRNAs, Aptamers in Neuroinflammation and Neurodegenerative Disorders

Exploring the microRNAs and aptamers for their therapeutic role as biological drugs has expanded the horizon of its applicability against various human diseases, explicitly targeting the genetic materials. RNA-based therapeutics are widely being explored for the treatment and diagnosis of multiple diseases, including neurodegenerative disorders (NDD). Latter includes microRNA, aptamers, ribozymes, and small interfering RNAs (siRNAs), which control the gene expression mainly at the transcriptional strata. One RNA transcript translates into different protein types; hence, therapies targeted at the transcriptional sphere may have prominent and more extensive effects than alternative therapeutics. Unlike conventional gene therapy, RNAs, upon delivery, can either altogether abolish or alter the synthesis of the protein of interest, therefore, regulating their activities in a controlled and diverse manner. NDDs like Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, Prion disease, and others are characterized by deposition of misfolded protein such as amyloid-ß, tau, α-synuclein, huntingtin and prion proteins. Neuroinflammation, one of the perquisites for neurodegeneration, is induced during neurodegenerative pathogenesis. In this review, we discuss microRNAs and aptamers' role as two different RNA-based approaches for their unique ability to regulate protein production at the transcription level, hence offering many advantages over other biologicals. The microRNA acts either by alleviating the malfunctioning RNA expression or by working as a replacement to lost microRNA. On the contrary, aptamer act as a chemical antibody and forms an aptamer-target complex.

Practical Significance of Biomarkers in Axial Spondyloarthritis: Updates on Diagnosis, Disease Activity, and Prognosis

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that can lead to ankylosis by secondary ossification of inflammatory lesions, with progressive disability and a significant impact on quality of life. It is also a risk factor for the occurrence of comorbidities, especially cardiovascular diseases (CVDs), mood disorders, osteoporosis, and malignancies. Early diagnosis and treatment are needed to prevent or decrease functional decline and to improve the patient's prognosis. In respect of axSpA, there is an unmet need for biomarkers that can help to diagnose the disease, define disease activity and prognosis, and establish personalized treatment approaches. The aim of this review was to summarize the available information regarding the most promising biomarkers for axSpA. We classified and identified six core categories of biomarkers: (i) systemic markers of inflammation; (ii) molecules involved in bone homeostasis; (iii) HLA-B27 and newer genetic biomarkers; (iv) antibody-based biomarkers; (v) microbiome biomarkers; and (vi) miscellaneous biomarkers. Unfortunately, despite efforts to validate new biomarkers, few of them are used in clinical practice; however, we believe that these studies provide useful data that could aid in better disease management.

Is liquid biopsy mature enough for the diagnosis of Alzheimer’s disease?

The preclinical diagnosis and clinical practice for Alzheimer’s disease (AD) based on liquid biopsy have made great progress in recent years. As liquid biopsy is a fast, low-cost, and easy way to get the phase of AD, continual efforts from intense multidisciplinary studies have been made to move the research tools to routine clinical diagnostics. On one hand, technological breakthroughs have brought new detection methods to the outputs of liquid biopsy to stratify AD cases, resulting in higher accuracy and efficiency of diagnosis. On the other hand, diversiform biofluid biomarkers derived from cerebrospinal fluid (CSF), blood, urine, Saliva, and exosome were screened out and biologically verified. As a result, more detailed knowledge about the molecular pathogenesis of AD was discovered and elucidated. However, to date, how to weigh the reports derived from liquid biopsy for preclinical AD diagnosis is an ongoing question. In this review, we briefly introduce liquid biopsy and the role it plays in research and clinical practice. Then, we summarize the established fluid-based assays of the current state for AD diagnostic such as ELISA, single-molecule array (Simoa), Immunoprecipitation–Mass Spectrometry (IP–MS), liquid chromatography–MS, immunomagnetic reduction (IMR), multimer detection system (MDS). In addition, we give an updated list of fluid biomarkers in the AD research field. Lastly, the current outstanding challenges and the feasibility to use a stand-alone biomarker in the joint diagnostic strategy are discussed.

The Potential Role of miRNA-Regulated Autophagy in Alzheimer’s Disease

As a neurodegenerative disease, Alzheimer’s disease (AD) shows a higher incidence during the aging process, mainly revealing the characteristics of a significant decrease in cognition, uncontrolled emotion, and reduced learning and memory capacity, even leading to death. In the prevention and treatment of AD, some pharmacological therapy has been applied in clinical practice. Unfortunately, there are still limited effective treatments for AD due to the absence of clear and defined targets. Currently, it is recognized that the leading causes of AD include amyloid-β peptide (Aβ) deposition, hyperphosphorylation of tau protein, neurofibrillary tangles, mitochondrial dysfunction, and inflammation. With in-depth mechanistic exploration, it has been found that these causes are highly correlated with the dysfunctional status of autophagy. Numerous experimental results have also confirmed that the development and progression of AD is accompanied by an abnormal functional status of autophagy; therefore, regulating the functional status of autophagy has become one of the important strategies for alleviating or arresting the progression of AD. With the increasing attention given to microRNAs (miRNAs), more and more studies have found that a series of miRNAs are involved in the development and progression of AD through the indirect regulation of autophagy. Therefore, regulating autophagy through targeting these miRNAs may be an essential breakthrough for the prevention and treatment of AD. This article summarizes the regulation of miRNAs in autophagy, with the aim of providing a new theoretical reference point for the prevention and treatment of AD through the indirect regulation of miRNA-mediated autophagy.

Diagnosis and Drug Prediction of Parkinson's Disease Based on Immune-Related Genes

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Immune mechanisms play an important role in the development of PD. The purpose of this study was to identify potential differentially expressed immune-related genes (IRGs), signaling pathways, and drugs in PD, which may provide new diagnostic markers and therapeutic targets for PD. Differentially expressed genes (DEGs) and IRGs were respectively obtained from the Gene Expression Omnibus (GEO) dataset and the ImmPort database. Weighted gene co-expression network analysis (WGCNA) was utilized to further identify hub IRGs. Core IRGs were obtained by intersection of DEGs and hub genes in the module of WGCNA, followed by construction of diagnostic models and regulation network establishment of long non-coding RNAs (lncRNAs)-miRNAs-diagnostic IRGs. Analysis of functional enrichment and protein-protein interaction (PPI) network and identification of related drugs of DEGs was performed. LILRB3 and CSF3R were identified as potential diagnostic markers for PD. Two regulatory pairs were identified based on LILRB3 and CSF3R, including XIST-hsa-miR-214-3p/hsa-miR-761-LILRB3 and XIST-hsa-miR-485-5p/hsa-miR-654-5p-CSF3R. LEP and IL1A were drug targets of Olanzapine. MMP9 and HSP90AB1 were drug targets of Bevacizumab. In addition, LEP and MMP9 were respectively drug targets of Lovastatin and Celecoxib. Herpes simplex infection (involved TNFRSF1A) and cytokine-cytokine receptor interaction (involved CSF3R, LEP, and IL1A) were the most remarkably enriched signaling pathways of DEGs. Identified IRGs and related signaling pathways may play critical roles in the development of PD. Additionally, LILRB3 and CSF3R can be considered as potential immune-related diagnostic markers for PD. LEP, IL1A, MMP9, and HSP90AB1 may be regarded as immune-related therapeutic targets for PD.

Regulation of microRNAs in Alzheimer´s disease, type 2 diabetes, and aerobic exercise training

Alzheimer's disease (AD) is the most common type of dementia. The evolution and aggregation of amyloid beta (β) oligomers is linked to insulin resistance in AD, which is also the major characteristic of type 2 diabetes (T2D). Being physically inactive can contribute to the development of AD and/or T2D. Aerobic exercise training (AET), a type of physical exercise, can be useful in preventing or treating the negative outcomes of AD and T2D. AD, T2D and AET can regulate the expression of microRNAs (miRNAs). Here, we review some of the changes in miRNAs expression regulated by AET, AD and T2D. MiRNAs play an important role in the gene regulation of key signaling pathways in both pathologies, AD and T2D. MiRNA dysregulation is evident in AD and has been associated with several neuropathological alterations, such as the development of a reactive gliosis. Expression of miRNAs are associated with many pathophysiological mechanisms involved in T2D like insulin synthesis, insulin resistance, glucose intolerance, hyperglycemia, intracellular signaling, and lipid profile. AET regulates miRNAs levels. We identified 5 miRNAs (miR-21, miR-29a/b, miR-103, miR-107, and miR-195) that regulate gene expression and are modulated by AET on AD and T2D. The identified miRNAs are potential targets to treat the symptoms of AD and T2D. Thus, AET is a non-pharmacological tool that can be used to prevent and fight the negative outcomes in AD and T2D.

Role of miRNAs in Neurodegeneration: From Disease Cause to Tools of Biomarker Discovery and Therapeutics

Neurodegenerative diseases originate from neuronal loss in the central nervous system (CNS). These debilitating diseases progress with age and have become common due to an increase in longevity. The National Institute of Environmental Health Science’s 2021 annual report suggests around 6.2 million Americans are living with Alzheimer’s disease, and there is a possibility that there will be 1.2 million Parkinson’s disease patients in the USA by 2030. There is no clear-cut universal mechanism for identifying neurodegenerative diseases, and therefore, they pose a challenge for neurobiology scientists. Genetic and environmental factors modulate these diseases leading to familial or sporadic forms. Prior studies have shown that miRNA levels are altered during the course of the disease, thereby suggesting that these noncoding RNAs may be the contributing factor in neurodegeneration. In this review, we highlight the role of miRNAs in the pathogenesis of neurodegenerative diseases. Through this review, we aim to achieve four main objectives: First, we highlight how dysregulation of miRNA biogenesis led to these diseases. Second, we highlight the computational or bioinformatics tools required to identify the putative molecular targets of miRNAs, leading to biological molecular pathways or mechanisms involved in these diseases. Third, we focus on the dysregulation of miRNAs and their target genes leading to several neurodegenerative diseases. In the final section, we highlight the use of miRNAs as potential diagnostic biomarkers in the early asymptomatic preclinical diagnosis of these age-dependent debilitating diseases. Additionally, we discuss the challenges and advances in the development of miRNA therapeutics for brain targeting. We list some of the innovative strategies employed to deliver miRNA into target cells and the relevance of these viral and non-viral carrier systems in RNA therapy for neurodegenerative diseases. In summary, this review highlights the relevance of studying brain-enriched miRNAs, the mechanisms underlying their regulation of target gene expression, their dysregulation leading to progressive neurodegeneration, and their potential for biomarker marker and therapeutic intervention. This review thereby highlights ways for the effective diagnosis and prevention of these neurodegenerative disorders in the near future.

Sporadic Alzheimer's Disease- and Neurotoxicity-Related microRNAs Affecting Key Events of Tau-Driven Adverse Outcome Pathway Toward Memory Loss

BACKGROUND

A complex network of aging-related homeostatic pathways that are sensitive to further deterioration in the presence of genetic, systemic, and environmental risk factors, and lifestyle, is implicated in the pathogenesis of progressive neurodegenerative diseases, such as sporadic (late-onset) Alzheimer's disease (sAD).

OBJECTIVE

Since sAD pathology and neurotoxicity share microRNAs (miRs) regulating common as well as overlapping pathological processes, environmental neurotoxic compounds are hypothesized to exert a risk for sAD initiation and progression.

METHODS

Literature search for miRs associated with human sAD and environmental neurotoxic compounds was conducted. Functional miR analysis using PathDip was performed to create miR-target interaction networks.

RESULTS

The identified miRs were successfully linked to the hypothetical starting point and key events of the earlier proposed tau-driven adverse outcome pathway toward memory loss. Functional miR analysis confirmed most of the findings retrieved from literature and revealed some interesting findings. The analysis identified 40 miRs involved in both sAD and neurotoxicity that dysregulated processes governing the plausible adverse outcome pathway for memory loss.

CONCLUSION

Creating miR-target interaction networks related to pathological processes involved in sAD initiation and progression, and environmental chemical-induced neurotoxicity, respectively, provided overlapping miR-target interaction networks. This overlap offered an opportunity to create an alternative picture of the mechanisms underlying sAD initiation and early progression. Looking at initiation and progression of sAD from this new angle may open for new biomarkers and novel drug targets for sAD before the appearance of the first clinical symptoms.

The Neuroepigenetic Landscape of Vertebrate and Invertebrate Models of Neurodegenerative Diseases

Vertebrate and invertebrate models of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, have been paramount to our understanding of the pathophysiology of these conditions; however, the brain epigenetic landscape is less well established in these disease models. DNA methylation, histone modifications, and microRNAs are among commonly studied mechanisms of epigenetic regulation. Genome-wide studies and candidate studies of specific methylation marks, histone marks, and microRNAs have demonstrated the dysregulation of these mechanisms in models of neurodegenerative diseases; however, the studies to date are scarce and inconclusive and the implications of many of these changes are still not fully understood. In this review, we summarize epigenetic changes reported to date in the brain of vertebrate and invertebrate models used to study neurodegenerative diseases, specifically diseases affecting the aging population. We also discuss caveats of epigenetic research so far and the use of disease models to understand neurodegenerative diseases, with the aim of improving the use of model organisms in this context in future studies.

Autophagy and apoptosis cascade: which is more prominent in neuronal death?

Autophagy and apoptosis are two crucial self-destructive processes that maintain cellular homeostasis, which are characterized by their morphology and regulated through signal transduction mechanisms. These pathways determine the fate of cellular organelle and protein involved in human health and disease such as neurodegeneration, cancer, and cardiovascular disease. Cell death pathways share common molecular mechanisms, such as mitochondrial dysfunction, oxidative stress, calcium ion concentration, reactive oxygen species, and endoplasmic reticulum stress. Some key signaling molecules such as p53 and VEGF mediated angiogenic pathway exhibit cellular and molecular responses resulting in the triggering of apoptotic and autophagic pathways. Herein, based on previous studies, we describe the intricate relation between cell death pathways through their common genes and the role of various stress-causing agents. Further, extensive research on autophagy and apoptotic machinery excavates the implementation of selective biomarkers, for instance, mTOR, Bcl-2, BH3 family members, caspases, AMPK, PI3K/Akt/GSK3β, and p38/JNK/MAPK, in the pathogenesis and progression of neurodegenerative diseases. This molecular phenomenon will lead to the discovery of possible therapeutic biomolecules as a pharmacological intervention that are involved in the modulation of apoptosis and autophagy pathways. Moreover, we describe the potential role of micro-RNAs, long non-coding RNAs, and biomolecules as therapeutic agents that regulate cell death machinery to treat neurodegenerative diseases. Mounting evidence demonstrated that under stress conditions, such as calcium efflux, endoplasmic reticulum stress, the ubiquitin-proteasome system, and oxidative stress intermediate molecules, namely p53 and VEGF, activate and cause cell death. Further, activation of p53 and VEGF cause alteration in gene expression and dysregulated signaling pathways through the involvement of signaling molecules, namely mTOR, Bcl-2, BH3, AMPK, MAPK, JNK, and PI3K/Akt, and caspases. Alteration in gene expression and signaling cascades cause neurotoxicity and misfolded protein aggregates, which are characteristics features of neurodegenerative diseases. Excessive neurotoxicity and misfolded protein aggregates lead to neuronal cell death by activating death pathways like autophagy and apoptosis. However, autophagy has a dual role in the apoptosis pathways, i.e., activation and inhibition of the apoptosis signaling. Further, micro-RNAs and LncRNAs act as pharmacological regulators of autophagy and apoptosis cascade, whereas, natural compounds and chemical compounds act as pharmacological inhibitors that rescue neuronal cell death through inhibition of apoptosis and autophagic cell death.

All roads lead to Rome - a review of the potential mechanisms by which exerkines exhibit neuroprotective effects in Alzheimer's disease

Age-related neurodegenerative disorders such as Alzheimer’s disease (AD) have become a critical public health issue due to the significantly extended human lifespan, leading to considerable economic and social burdens. Traditional therapies for AD such as medicine and surgery remain ineffective, impractical, and expensive. Many studies have shown that a variety of bioactive substances released by physical exercise (called “exerkines”) help to maintain and improve the normal functions of the brain in terms of cognition, emotion, and psychomotor coordination. Increasing evidence suggests that exerkines may exert beneficial effects in AD as well. This review summarizes the neuroprotective effects of exerkines in AD, focusing on the underlying molecular mechanism and the dynamic expression of exerkines after physical exercise. The findings described in this review will help direct research into novel targets for the treatment of AD and develop customized exercise therapy for individuals of different ages, genders, and health conditions.

Antisense oligonucleotides for Alzheimer's disease therapy: from the mRNA to miRNA paradigm

Alzheimer's disease (AD) represents a particular therapeutic challenge because its aetiology is very complex, with dynamic progression from preclinical to clinical stages. Several potential therapeutic targets and strategies were tested for AD, in over 2000 clinical trials, but no disease-modifying therapy exists. This failure indicates that AD, as a multifactorial disease, may require multi-targeted approaches and the delivery of therapeutic molecules to the right place and at the right disease stage. Opportunities to meet the challenges of AD therapy appear to come from recent progress in knowledge and methodological advances in the design, synthesis, and targeting of brain mRNA and microRNA with synthetic antisense oligonucleotides (ASOs). Several types of ASOs allow the utilisation of different mechanisms of posttranscriptional regulation and offer enhanced effects over alternative therapeutics. This article reviews ASO-based approaches and targets in preclinical and clinical trials for AD, and presents the future perspective on ASO therapies for AD.

MiR-214-3p plays a protective role in diabetic neuropathic rats by regulating Nav1.3 and TLR4

This study aimed to investigate the functions of miR-214-3p in diabetic neuropathic rodents. The diabetic neuropathy was induced by intraperitoneal injection of streptozotocin (STZ) in rats, and miR-214-3p was delivered via tail vein injection of lentivirus. Hot or cold stimulus tests demonstrated that STZ induced thermal hyperalgesia. Neurophysiological measurements revealed that motor and sensory nerve conduction velocity and nerve blood flow were decreased in diabetic neuropathic rats. However, the STZ-induced hyperalgesia, and reduced nerve conduction velocity and nerve blood flow were all significantly reversed by miR-214-3p administration. HE staining, TUNEL, ELISA, and immunoblotting demonstrated that STZ led to obvious pathological lesion, cell apoptosis, and inflammation in dorsal root ganglion (DRG), evidenced by altered levels of apoptosis-related protein molecules and inflammatory factors, and activation of Toll-like receptor 4 (TLR4)/myeloid differentiation primary response gene 88/nuclear factor kappa B signaling. The pathological alterations in diabetic neuropathic rats in DRG were significantly ameliorated by miR-214-3p application. In addition, sodium channel protein type 3 subunit alpha isoform 1 (Nav1.3) and TLR4 were identified as targets of miR-214-3p via dual-luciferase reporter assay. MiR-214-3p may play its roles by downregulating Nav1.3 and TLR4. In summary, miR-214-3p alleviated diabetes-induced nerve injury, and pathological lesion, cell apoptosis, and inflammation in DRG by regulating Nav1.3 and TLR4 in STZ-induced rats. These findings may provide novel therapeutic targets for clinical treatment of diabetic neuropathy.

MicroRNA-214-5p involves in the protection effect of Dexmedetomidine against neurological injury in Alzheimer's disease via targeting the suppressor of zest 12

OBJECTIVE

Alzheimer's disease (AD) is a neurological disease. Dexmedetomidine (Dex) has been evidenced to exert neuroprotective effects on multiple neurological diseases, while the function of microRNA(miR)- 214-5p on Dex-mediated AD progression via targeting the suppressor of zest 12 (SUZ12) remains unclear. This study obligates to investigate the regulatory functions of Dex, miR-214-5p and SUZ12 on AD.

METHODS

The expression of miR-214-5p and SUZ12 in APPswe/PS1dE9 mice (hereinafter referred to as AD mice) was examined. Thereafter, the AD mice were treated with Dex or increased miR-214-5p or reduced SUZ12 to determine the spatial memory ability, apoptosis of hippocampal neurons and the contents of serum inflammatory and oxidative stress factors of AD mice. Finally, the target relationship between miR-214-5p and SUZ12 was detected.

RESULTS

MiR-214-5p was reduced and SUZ12 was elevated in AD mice. Dex administration reduced the apoptosis of hippocampal neurons, the contents of serum inflammatory factor and oxidative stress, and attenuated the cognitive impairment of AD mice accompanied by up-regulated miR-214-5p and down-regulated SUZ12, and the overexpression of miR-214-5p or reduction of SUZ12 could effectively enhance the Dex-treated effects on AD mice. MiR-214-5p targeted SUZ12.

CONCLUSION

Dex may have a potential neuroprotective effect on AD via the miR-214-5p/SUZ12 axis. This study provides novel therapeutic targets for AD treatment.

miRNA-124-3p targeting of LPIN1 attenuates inflammation and apoptosis in aged male rats cardiopulmonary bypass model of perioperative neurocognitive disorders

Perioperative neurocognitive disorder (PND) is recently recommended to define the cognitive decrease during the perioperative period. However, the disease's underlying mechanisms remain unclear. MicroRNAs (miRNAs) are noncoding RNAs that play a vital role in regulating neuroregeneration and neuronal apoptosis. In this study, miR-124-3p was significantly reduced in the PND rat model after a cardiopulmonary bypass (CPB) procedure. MicroRNA-124 (miR-124)-3p-overexpressed lentivirus was constructed and injected via the intracerebroventricular method before CPB. Morris Water Maze test (WMW) and the Open-Field test (OFT) were used to measure behavior changes, data shows decline of cognitive function of rats after CPB. PND rats expressed higher Aβ and p-Tau Protein by using immunohistochemistry (IHC) analyses and Enzyme-Linked Immune Sorbent Assay (ELISA). Moreover, the results of IHC, ELISA, Western Blot analysis (WB) and Terminal-deoxynucleotidyl Transferase Mediated Nick End Labeling Assay (TUNEL) showed CPB procedure induced inflammation and apoptosis in rats with PND. The data also revealed the protective function of miR-124-3p overexpression against PND in relieving inflammation, cell apoptosis, and alleviating repaired cognitive function. Moreover, miR-124-3p was predicted by directly targeting LPIN1. This study gives a novel viewpoint that miR-124-3p could improve the state of PND via modulating LPIN1, therefore providing a new strategy for preventing and treating PND in a preclinical application.

miR‑214 ameliorates sepsis‑induced acute kidney injury via PTEN/AKT/mTOR‑regulated autophagy

Previous studies have suggested that oxidative stress and autophagy results in acute kidney injury (AKI) during sepsis and microRNA (miR)-214 serves a vital role in the protection of kidneys subjected to oxidative stress. The present study aimed to test whether the renoprotection of miR-214 is related to autophagy in sepsis. The role of autophagy was investigated in a mouse model of cecal ligation and puncture (CLP). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to analyze the expression of miR-214. The structure and function of kidneys harvested from the mice were evaluated. Kidney autophagy levels were detected with immunohistochemical, immunofluorescent and western blotting. It was found that miR-214 could alleviate AKI in septic mice by inhibiting the level of kidney autophagy. Furthermore, miR-214 inhibited autophagy by silencing PTEN expression in the kidney tissues of septic mice. These findings indicated that miR-214 ameliorated CLP-induced AKI by reducing oxidative stress and inhibiting autophagy through the regulation of the PTEN/AKT/mTOR pathway.

The Role of Non-coding RNAs in Alzheimer's Disease: From Regulated Mechanism to Therapeutic Targets and Diagnostic Biomarkers

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder. AD is characterized by the production and aggregation of beta-amyloid (Aβ) peptides, hyperphosphorylated tau proteins that form neurofibrillary tangles (NFTs), and subsequent neuroinflammation, synaptic dysfunction, autophagy and oxidative stress. Non-coding RNAs (ncRNAs) can be used as potential therapeutic targets and biomarkers due to their vital regulatory roles in multiple biological processes involved in disease development. The involvement of ncRNAs in the pathogenesis of AD has been increasingly recognized. Here, we review the ncRNAs implicated in AD and elaborate on their main regulatory pathways, which might have contributions for discovering novel therapeutic targets and drugs for AD.

SAMP8 Mice as a Model of Age-Related Cognition Decline with Underlying Mechanisms in Alzheimer's Disease

Alzheimer's disease (AD) is a highly age-related cognitive decline frequently attacking the elderly. Senescence-accelerated mouse-prone 8 (SAMP8) is an ideal model to study AD, displaying age-related learning and memory disorders. SAMP8 mice exhibit most features of pathogenesis of AD, including an abnormal expression of anti-aging factors, oxidative stress, inflammation, amyloid-β (Aβ) deposits, tau hyperphosphorylation, endoplasmic reticulum stress, abnormal autophagy activity, and disruption of intestinal flora. SAMP8 mice, therefore, have visualized the understanding of AD, and also provided effective ways to find new therapeutic targets. This review focused on the age-related pathogenesis in SAMP8 mice, to advance the understanding of age-related learning and memory decline and clarify the mechanisms. Furthermore, this review will provide extensive foundations for SAMP8 mice used in therapeutics for AD.

PADI4 mediates autophagy and participates in the role of ganoderic acid A monomers in delaying the senescence of Alzheimer's cells through the Akt/mTOR pathway

The effects of PADI4 and GAA on the senescence of Alzheimer's cells were explored in the present work. HT22 cells were treated with Aβ25-35 to establish an Alzheimer's model and were then treated with different concentrations of GAA and transfected with a siPADI4 lentiviral vector. GAA could reverse the effects of Aβ25-35 on inhibiting cell viability and promoting apoptosis and senescence. siPADI4 reduced Aβ25-35-induced cell viability and upregulated Aβ25-35-induced cell apoptosis and senescence, as well as partially reversed the effect of GAA on cells, and these results were confirmed by detecting the expressions of senescence- and apoptosis-related proteins. In addition, siPADI4 was found to promote the phosphorylation of Akt and mTOR, which was partially reversed by GAA. In conclusion, PADI4 mediates autophagy and participates in the role of GAA monomers in delaying the senescence of Alzheimer's cells through the Akt/mTOR pathway.

A Systematic Review of Current Progresses in the Nucleic Acid-Based Therapies for Neurodegeneration with Implications for Alzheimer's Disease

Recently, manipulation of gene expression and switching genes on or off highlight the potential of nucleic acid-based therapies (NA-BTs). Alzheimer's Disease (AD) is a common devastating neurodegenerative disease (NDs) responsible for 60-80% of all cases of dementia and predicted as a main public health concern among aged populations. The aim of this study was to outline the current research in the field of NA-BTs for the treatment of AD disabilities, including strategies to suppress the memory and learning defects, to promote recovery processes, and to reinforce social relationships in these patients. This review was performed via evaluating PubMed reported studies from January 2010 to November 2019. Also, reference lists were checked to find additional studies. All intermediation or complementarity of animal models, case-control and cohort studies, and controlled trials (CTs) on specific NA-BTs to AD were acceptable, although in vitro studies were excluded due to the considerable diversities and heterogeneities. After removing the duplicates according to preferred reporting items for systematic reviews and meta-analyses (PRISMA) instruction, we merged remaining titles across search databases. There are 48 ongoing studies related to the application of nucleic acids in the treatment and diagnosis of AD where more consideration is given to DNA targeting strategies (18 targets for vectors and aptamers), antisense oligonucleotides (10 targets), micro-RNAs mimics (7 targets), antagomiRs (6 targets), small interferences-RNAs (5 targets), as well as mRNAs (2 targets) respectively. All of these targets are grouped into 4 categories according to their role in molecular pathways where amyloid-β (18 targets), neural survival (11 targets), memory and cognition (8 targets), and tau (3 targets) are more targeted pathways, respectively. With recent successes in the systemic delivery of nucleic acids via intravenous injection; it is worth investing in the production of new-generation medicines. There are still several challenges for NA-BTs including, their delivery to the effective modulators, mass production at low cost, sustaining efficacy and minimizing off-target effects. Regarding miRNA-based therapies, given the obvious involvement of miRNAs in numerous facets of brain disease, and the many sophisticated techniques for delivery to the brain, miRNA-based therapies will make new hope for the treatment of neurological diseases such as AD.

The Eminent Role of microRNAs in the Pathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is an irrevocable neurodegenerative condition characterized by the presence of senile plaques comprising amassed β-amyloid peptides (Aβ) and neurofibrillary tangles mainly comprising extremely phosphorylated Tau proteins. Recent studies have emphasized the role of microRNAs (miRNAs) in the development of AD. A number of miRNAs, namely, miR-200a-3p, miR-195, miR-338-5p, miR-34a-5p, miR-125b-5p, miR-132, miR-384, miR-339-5p, miR-135b, miR-425-5p, and miR-339-5p, have been shown to participate in the development of AD through interacting with BACE1. Other miRNAs might affect the inflammatory responses in the course of AD. Aberrant expression of several miRNAs in the plasma samples of AD subjects has been shown to have the aptitude for differentiation of AD subjects from healthy subjects. Finally, a number of AD-modifying agents affect miRNA profile in cell cultures or animal models. We have performed a comprehensive search and summarized the obtained data about the function of miRNAs in AD in the current review article.

Mitochondria-associated endoplasmic reticulum membranes: At the crossroad between familiar and sporadic Alzheimer's disease

Alzheimer's disease (AD) is the leading cause of dementia and is incurable. The widely accepted amyloid hypothesis failed to produce efficient clinical therapies. In contrast, there is increasing evidence suggesting that the disruption of mitochondria-associated endoplasmic reticulum (ER) membranes (MAM) is a critical upstream event of AD pathogenesis. Here, we review MAM's role in some AD symptoms such as plaque formation, tau hyperphosphorylation, synaptic loss, aberrant lipid synthesis, disturbed calcium homeostasis, and abnormal autophagy. At last, we proposed that MAM plays a central role in familial AD (FAD) and sporadic AD (SAD).

Enhanced Autolysosomal Function Ameliorates the Inflammatory Response Mediated by the NLRP3 Inflammasome in Alzheimer's Disease

The pathogenesis of Alzheimer’s disease (AD) involves activation of many NLRP3 inflammatory bodies, which may be related to amyloid β peptide and aggregation of misfolded proteins. Autophagy is an important regulator of inflammatory bodies. However, autophagy shows dynamic changes in the development of AD, and its role in inflammation remains controversial. In this study, the key link between autophagic disorders and the NLRP3 inflammasome in AD was investigated. APP/PS1 double transgenic mice and C57 mice with Aβ_25–35 injected into the lateral ventricle were used as two animal models of AD. Immunofluorescence staining and Western blot analysis showed that NLRP3 inflammasome-related proteins and inflammatory cytokines, such as IL-1α, IL-1β, IL-6, IL-12, and TNF-α, were increased and microglia were activated in the brains of both AD animal models. Endogenous overexpression of the APPswe gene and exogenous addition of Aβ_25–35 increased the expression of NLRP3 inflammasome-related proteins, while exogenous Aβ_25–35 intervention more significantly activated inflammation. Furthermore, LC3 was increased in the AD animal and cell models, and the level of Lamp1 decreased. After overexpression of the primary regulator of lysosomal biogenesis, TFEB, the lysosome protein Lamp1 was increased, and LC3 and inflammatory protein expression were decreased. These results suggest that the NLRP3 inflammasome-mediated inflammatory response is activated in AD animal and cell models, which may be related to the decline in autolysosome function. Overexpression of the TFEB protein can reduce the inflammatory response by improving autolysosome function in AD model cells.

MicroRNAs Regulating Autophagy in Neurodegeneration

Social and economic impacts of neurodegenerative diseases (NDs) become more prominent in our constantly aging population. Currently, due to the lack of knowledge about the aetiology of most NDs, only symptomatic treatment is available for patients. Hence, researchers and clinicians are in need of solid studies on pathological mechanisms of NDs. Autophagy promotes degradation of pathogenic proteins in NDs, while microRNAs post-transcriptionally regulate multiple signalling networks including autophagy. This chapter will critically discuss current research advancements in the area of microRNAs regulating autophagy in NDs. Moreover, we will introduce basic strategies and techniques used in microRNA research. Delineation of the mechanisms contributing to NDs will result in development of better approaches for their early diagnosis and effective treatment.

Competing Endogenous RNA Networks as Biomarkers in Neurodegenerative Diseases

Protein aggregation is classically considered the main cause of neuronal death in neurodegenerative diseases (NDDs). However, increasing evidence suggests that alteration of RNA metabolism is a key factor in the etiopathogenesis of these complex disorders. Non-coding RNAs are the major contributor to the human transcriptome and are particularly abundant in the central nervous system, where they have been proposed to be involved in the onset and development of NDDs. Interestingly, some ncRNAs (such as lncRNAs, circRNAs and pseudogenes) share a common functionality in their ability to regulate gene expression by modulating miRNAs in a phenomenon known as the competing endogenous RNA mechanism. Moreover, ncRNAs are found in body fluids where their presence and concentration could serve as potential non-invasive biomarkers of NDDs. In this review, we summarize the ceRNA networks described in Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis and spinocerebellar ataxia type 7, and discuss their potential as biomarkers of these NDDs. Although numerous studies have been carried out, further research is needed to validate these complex interactions between RNAs and the alterations in RNA editing that could provide specific ceRNET profiles for neurodegenerative disorders, paving the way to a better understanding of these diseases.

LncRNA BACE1-AS Promotes Autophagy-Mediated Neuronal Damage Through The miR-214-3p/ATG5 Signalling Axis In Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease and is characterized by progressive memory loss and cognitive dysfunction. Long non-coding RNAs (lncRNAs) have been shown to be among the most promising biomarkers and therapeutic targets of AD. Here, we aimed to investigate whether lncRNA BACE1-AS plays a role in the potential mechanisms of AD. The expression of BACE1-AS, miR-214-3p and ATG5 mRNA was detected using qRT-PCR. The expression of the LC3, P62, ATG5, Bcl-2, p-Tau and cleaved-caspase 3 proteins was examined using western blot analysis. Cell apoptosis, cytotoxicity and ROS levels were estimated using flow cytometry, an LDH kit and a DCFH-DA assay, respectively. The interaction between BACE1-AS or ATG5 and miR-214-3p was validated using a dual-luciferase reporter assay. HE staining and a TUNEL assay were employed to evaluate hippocampal neuronal injury. The BACE1-AS level was found to be upregulated in serum samples of AD patients, brain tissues of AD transgenic (Tg) mice and Aβ_1-42-treated SH-SY5Y cells. Autophagy activity was increased in both Tg mice and Aβ_1-42-treated cells. BACE1-AS knockdown alleviated Aβ_1-42-induced cell injury. Rapamycin abolished the protective effects of sh BACE1-AS against Aβ_1-42 induced cell injury. BACE1-AS indirectly regulated ATG5 expression by binding miR-214-3p. The miR-214-3p inhibitor reversed the protective effects of sh BACE1-AS and sh ATG5 against Aβ_1-42-induced cell injury. Knockdown of BACE1-AS alleviated neuronal injury by repressing autophagy in vivo. Our findings demonstrate that silencing of BACE1-AS alleviated neuronal injury by regulating autophagy through the miR-214-3p/ATG5 signalling axis in AD.

The Functional Role of microRNAs in the Pathogenesis of Tauopathy

Tauopathies are neurodegenerative disorders which include Alzheimer's disease, Pick's disease, corticobasal degeneration, and progressive supranuclear palsy among others. Pathologically, they are characterized by the accumulation of highly phosphorylated and aggregated tau protein in different brain regions. Currently, the mechanisms responsible for their pathogenesis are not known, and for this reason, there is no cure. MicroRNAs (miRNAs) are abundantly present in the central nervous system where they act as master regulators of pathways considered important for tau post-translational modifications, metabolism, and clearance. Although in recent years, several miRNAs have been reported to be altered in tauopathy, we still do not know whether these changes contribute to the onset and progression of the disorder, or are secondary events following the development of tau neuropathology. Additionally, since miRNAs are relatively stable in biological fluids and their measurement is easy and non-invasive, these small molecules hold the potential to function as biomarkers for tauopathy. Herein, we showcase recent findings on the biological link between miRNAs and the pathogenesis of tauopathy, and present emerging evidence supporting their role as biomarkers and targets for novel therapies against them.

Melatonin exerts neuroprotective effects by inhibiting neuronal pyroptosis and autophagy in STZ-induced diabetic mice

Diabetes mellitus (DM) patients are at a higher risk of developing brain injury characterized by neuronal death. Melatonin, a hormone produced by the pineal gland, exerts neuroprotective effects against brain damage. However, the effect of melatonin on diabetes-induced brain injury has not been elucidated. This study was to evaluate the role of melatonin against neuronal death in DM and to elucidate the underlying mechanisms. Herein, we found that melatonin administration significantly alleviated the neuronal death in both streptozotocin (STZ)-induced diabetic mice and high glucose (HG)-treated neuronal cells. Melatonin inhibited neuronal pyroptosis and excessive autophagy, as evidenced by decreased levels of NLRP3, cleaved caspase-1, GSDMD-N, IL-1β, LC3, Beclin1, and ATG12 both in vivo and in vitro. MicroRNA-214-3p (miR-214-3p) was decreased in DM mice and HG-treated cells, and such a downregulation was corrected by melatonin, which was accompanied by repression of caspase-1 and ATG12. Furthermore, downregulation of miR-214-3p abrogated the anti-pyroptotic and anti-autophagic actions of melatonin in vitro. Our results indicate that melatonin exhibits a neuroprotective effect by inhibiting neuronal pyroptosis and excessive autophagy through modulating the miR-214-3p/caspase-1 and miR-214-3p/ATG12 axes, respectively, and it might be a potential agent for the treatment of brain damage in the setting of DM.

Biomarkers for Alzheimer's Disease Early Diagnosis

Alzheimer's disease (AD) is the most common cause of dementia, affecting the central nervous system (CNS) through the accumulation of intraneuronal neurofibrillary tau tangles (NFTs) and β-amyloid plaques. By the time AD is clinically diagnosed, neuronal loss has already occurred in many brain and retinal regions. Therefore, the availability of early and reliable diagnosis markers of the disease would allow its detection and taking preventive measures to avoid neuronal loss. Current diagnostic tools in the brain, such as magnetic resonance imaging (MRI), positron emission tomography (PET) imaging, and cerebrospinal fluid (CSF) biomarkers (Aβ and tau) detection are invasive and expensive. Brain-secreted extracellular vesicles (BEVs) isolated from peripheral blood have emerged as novel strategies in the study of AD, with enormous potential as a diagnostic evaluation of therapeutics and treatment tools. In addition; similar mechanisms of neurodegeneration have been demonstrated in the brain and the eyes of AD patients. Since the eyes are more accessible than the brain, several eye tests that detect cellular and vascular changes in the retina have also been proposed as potential screening biomarkers. The aim of this study is to summarize and discuss several potential markers in the brain, eye, blood, and other accessible biofluids like saliva and urine, and correlate them with earlier diagnosis and prognosis to identify individuals with mild symptoms prior to dementia.

MicroRNAs in Alzheimer's Disease: Function and Potential Applications as Diagnostic Biomarkers

Alzheimer’s disease (AD) is the most common form of dementia. Although the incidence of AD is high, the rates of diagnosis and treatment are relatively low. Moreover, effective means for the diagnosis and treatment of AD are still lacking. MicroRNAs (miRNAs, miRs) are non-coding RNAs that play regulatory roles by targeting mRNAs. The expression of miRNAs is conserved, temporal, and tissue-specific. Impairment of microRNA function is closely related to AD pathogenesis, including the beta-amyloid and tau hallmarks of AD, and there is evidence that the expression of some microRNAs differs significantly between healthy people and AD patients. These properties of miRNAs endow them with potential diagnostic and therapeutic value in the treatment of this debilitating disease. This review provides comprehensive information about the regulatory function of miRNAs in AD, as well as potential applications as diagnostic biomarkers.

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.

Modulation of MicroRNAs as a Potential Molecular Mechanism Involved in the Beneficial Actions of Physical Exercise in Alzheimer Disease

Alzheimer disease (AD) is one of the most common neurodegenerative diseases, affecting middle-aged and elderly individuals worldwide. AD pathophysiology involves the accumulation of beta-amyloid plaques and neurofibrillary tangles in the brain, along with chronic neuroinflammation and neurodegeneration. Physical exercise (PE) is a beneficial non-pharmacological strategy and has been described as an ally to combat cognitive decline in individuals with AD. However, the molecular mechanisms that govern the beneficial adaptations induced by PE in AD are not fully elucidated. MicroRNAs are small non-coding RNAs involved in the post-transcriptional regulation of gene expression, inhibiting or degrading their target mRNAs. MicroRNAs are involved in physiological processes that govern normal brain function and deregulated microRNA profiles are associated with the development and progression of AD. It is also known that PE changes microRNA expression profile in the circulation and in target tissues and organs. Thus, this review aimed to identify the role of deregulated microRNAs in the pathophysiology of AD and explore the possible role of the modulation of microRNAs as a molecular mechanism involved in the beneficial actions of PE in AD.

miR-214-3p Attenuates Sepsis-Induced Myocardial Dysfunction in Mice by Inhibiting Autophagy through PTEN/AKT/mTOR Pathway

Aims. More than half of the patients with sepsis would develop cardiac dysfunction, which is termed as sepsis-induced myocardial dysfunction (SIMD). Previous studies suggest that autophagy may play an important role in SIMD. The present study investigated whether miR-214-3p could attenuate SIMD by inhibiting autophagy. Main Methods. In this article, we investigated the role of autophagy in a mouse model of cecal ligation and puncture (CLP). The structure and function of hearts harvested from the mice were evaluated. Myocardial autophagy levels were detected with immunohistochemical, immunofluorescent, and Western blot. Key Findings. miR-214-3p can alleviate SIMD in septic mice by inhibiting the level of cardiac autophagy to attenuate myocardial dysfunction. Moreover, this study showed that miR-214-3p inhibited autophagy by silencing PTEN expression in the myocardial tissues of septic mice. Significance. This study showed that miR-214-3p attenuated SIMD through myocardial autophagy inhibition by silencing PTEN expression and activating the AKT/mTOR pathway. The present findings supported that miR-214-3p may be a potential therapeutic target for SIMD.

MicroRNA alterations in neuropathologic cognitive disorders with an emphasis on dementia: Lessons from animal models

Cognitive dysfunction is a state of losing or having difficulties in remembering, learning, focusing, or making decisions that impact individual healthy life. Small single-stranded and nonprotein coding RNAs, microRNAs (miRNAs) participate actively in regulatory processes, incorporate cognitive signaling pathways, and intensely affect cognitive evolution. miRNAs exert their modification activities through translational or transcriptional processes. Reportedly, cognitive impairment and dementia are rising, especially in developing countries. Herein we provided a brief review of original studies addressing miRNA changes in the most common neurological diseases with a focus on dementia and Alzheimer's disease. It must be noted that an increase in the level of certain miRNAs but a decrease in other ones deteriorate cognitive performance. The current review revealed that induction of miR-214-3p, miR-302, miR-21, miR- 200b/c, miR-207, miR-132, miR-188-3p and 5p, and miR-873 improved cognitive impairment in various cognitive tasks. On the other hand, intentionally lowering the level of miR-34a, miR-124, miR-574, and miR-191a enhanced cognitive function and memory. Synaptic dysfunction is a core cause of cognitive dysfunction; miRNA-34, miRNA-34-c, miRNA-124, miRNA-188-5p, miRNA-210-5p, miRNA-335-3p, and miRNA-134 strongly influence synaptic-related mechanisms. The downregulation of miRNA-132 aggregates both amyloid and tau in tauopathy. Concerning the massive burden of neurological diseases worldwide, the future challenge is the translation of animal model knowledge into the detection of pathophysiological stages of neurocognitive disorders and designing efficient therapeutic strategies. While the delivery procedure of agomir or antagomir miRNAs into the brain is invasive and only applied in animal studies, finding a safe and specific delivery route is a priority.

Knockdown of long non-coding RNA TUG1 depresses apoptosis of hippocampal neurons in Alzheimer's disease by elevating microRNA-15a and repressing ROCK1 expression

OBJECTIVE

Many studies have already suggested the role of long non-coding RNAs (lncRNAs) in Alzheimer's disease (AD), but the functions of lncRNA Taurine Upregulated Gene 1 (TUG1) in AD have been scarcely discussed. This study aims to verify how TUG1 affects hippocampal neurons in AD through modulation of microRNA-15a (miR-15a)/Rho-associated protein kinase 1 (ROCK1).

METHOD

AD mice was modeled through injection of β-amyloid 25-35 (Aβ25-35) into the lateral ventricle. After modeling, the mice were injected with altered TUG1 and/or miR-15a agomir lentiviruses. The spatial learning ability and memory ability of mice were detected through Morris water maze test. Hippocampal neuronal apoptosis and oxidative stress indicators in AD mice were then detected. The hippocampal neuron AD model was induced by Aβ25-35. Next, the neurons were, respectively, transfected with altered TUG1 vector and/or miR-15a mimics to determine the proliferation inhibition and apoptosis of hippocampal neurons. The interactions between TUG1 and miR-15a, and between miR-15a and ROCK1 were assessed using bioinformatic prediction, dual luciferase reporter gene assay and RNA-pull-down assay.

RESULTS

In the animal models, Aβ25-35-induced mice exhibited decreased spatial learning and memory ability, obvious pathological injury, promoted hippocampal neuronal apoptosis and decreased antioxidant ability. TUG1 silencing and miR-15a elevation improved spatial learning ability and memory ability, ameliorated pathological injury, depressed neuronal apoptosis, and strengthened antioxidant ability of hippocampal neurons in AD mice. In cellular models, Aβ25-35-treated hippocampal neurons presented inhibited neuronal viability and promoted neuronal apoptosis. TUG1 silencing and miR-15a elevation increased viability and limited apoptosis of Aβ25-35-treated hippocampal neurons. TUG1 specifically bound to miR-15a, and miR-15a targeted ROCK1.

CONCLUSION

Collectively, this study reveals that TUG1 knockdown restricts apoptosis of hippocampal neurons in AD by elevating miR-15a and suppressing ROCK1 expression, and provides a new therapeutic target for AD treatment.

The Regulation of microRNAs in Alzheimer's Disease

MicroRNAs are small non-coding nucleic acids that are responsible for regulating the gene expression by binding to the coding region and 3' and 5' un-translated region of target messenger RNA. Approximately 70% of known microRNAs are expressed in the brain and increasing evidences demonstrate the possible involvement of microRNAs in Alzheimer's disease (AD) according to the statistics. The characteristic symptoms of AD are the progressive loss of memory and cognitive functions due to the deposition of amyloid β (Aβ) peptide, intracellular aggregation of hyperphosphorylated Tau protein, the loss of synapses, and neuroinflammation, as well as dysfunctional autophagy. Therefore, microRNA-mediated regulation for above-mentioned changes may be the potential therapeutic strategies for AD. In this review, the role of specific microRNAs involved in AD and corresponding applications are systematically discussed, including positive effects associated with the reduction of Aβ or Tau protein, the protection of synapses, the inhibition of neuroinflammation, the mitigation of aging, and the induction of autophagy in AD. It will be beneficial to develop effective targets for establishing a cross link between pharmacological intervention and AD in the near future.

Molecular Pathogenesis and Interventional Strategies for Alzheimer's Disease: Promises and Pitfalls

Alzheimer's disease (AD) is a debilitating disorder characterized by age-related dementia, which has no effective treatment to date. β-Amyloid depositions and hyperphosphorylated tau proteins are the main pathological hallmarks, along with oxidative stress, N-methyl-d-aspartate (NMDA) receptor-mediated excitotoxicity, and low levels of acetylcholine. Current pharmacotherapy for AD only provides symptomatic relief and limited improvement in cognitive functions. Many molecules have been explored that show promising outcomes in AD therapy and can regulate cellular survival through different pathways. To have a vivid approach to strategize the treatment regimen, AD physiopathology should be better explained considering diverse etiological factors in conjunction with biochemical disturbances. This Review attempts to discuss different disease modification approaches and address the novel therapeutic targets of AD that might pave the way for new drug discovery using the well-defined targets for therapy of the disease.

Exploring the bi-directional relationship between autophagy and Alzheimer's disease

Alzheimer's disease (AD) is characterized by β-amyloid (Aβ) deposition and Tau phosphorylation, in which its pathogenesis has not been cleared so far. The metabolism of Aβ and Tau is critically affected by the autophagy. Abnormal autophagy is thought to be involved in the pathogenesis of AD, regulating autophagy may become a new strategy for AD treatment. In the early stage of AD, the presence of Aβ and Tau can induce autophagy to promote their clearance by means of mTOR-dependent and independent manners. As AD progress, the autophagy goes aberrant. As a result, Aβ and Tau generate continually, which aggravates both autophagy dysfunction and AD. Besides, several related genes and proteins of AD can also adapt autophagy to make an effect on the AD development. There seems to be a bi-directional relationship between AD pathology and autophagy. At present, this article reviews this relationship from these aspects: (a) the signaling pathways of regulating autophagy; (b) the relationships between the autophagy and the processing of Aβ; (c) Aβ and Tau cause autophagy dysfunction; (d) normal autophagy promotes the clearance of Aβ and Tau; (e) the relationships between the autophagy and both genes and proteins related to AD: TFEB, miRNAs, Beclin-1, Presenilin, and Nrf2; and (f) the small molecules regulating autophagy on AD therapy. All of the above may help to further elucidate the pathogenesis of AD and provide a theoretical basis for clinical treatment of AD.

Plasma MicroRNA Expression Profiles in Psoriasis

Background

Psoriasis is an immune-mediated inflammatory chronic skin disease characterized by chronic inflammation in the dermis, parakeratosis, and excessive epidermal growth. MicroRNAs (miRNAs) are key regulators of immune responses. Although differential expression of miRNAs has been reported in certain inflammatory autoimmune diseases, their role in psoriasis has not been fully illuminated. Our aims were to confirm plasma miRNA expression signatures in psoriasis and to examine their potential influence on psoriasis pathogenesis.

Methods

A miRNome PCR array was used to analyse the plasma of psoriasis patients and healthy donors. We performed miRNA pathway enrichment and target gene network analyses on psoriasis plasma samples.

Results

We found several specific plasma miRNA signatures relevant to psoriasis. The miRNAs targeted pathways associated with psoriasis, such as the VEGF, MAPK, and WNT signaling pathways. Network analysis revealed pivotal deregulated plasma miRNAs and their relevant target genes and pathways regulating psoriasis pathogenesis.

Conclusions

This study analysed the expression of plasma miRNAs and their target pathways, elucidating the pathogenesis of psoriasis; these results may be used to design novel therapeutic strategies and to identify diagnostic biomarkers for psoriasis.

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.