miR-200a-3p promotes b-Amyloid-induced neuronal apoptosis through down-regulation of SIRT1 in Alzheimer's disease

Gga-miR-200a-3p suppresses avian reovirus-induced apoptosis and viral replication via targeting GRB2

Avian reovirus (ARV) is a significant pathogen that causes various clinical diseases in chickens, including viral arthritis, chronic respiratory diseases, retarded growth, and malabsorption syndrome. These conditions result in substantial economic losses for the global poultry industry. MicroRNAs (miRNAs), a type of small noncoding RNAs that regulate gene expression post transcriptionally by silencing or degrading their RNA targets, play crucial roles in response to pathogenic infections. In this study, transfection of DF-1 cells with gga-miR-200a-3p, an upregulated miRNA observed in ARV-infected cells, significantly suppressed ARV-induced apoptosis by directly targeting GRB2 and impeded ARV replication. Conversely, knockdown of endogenous gga-miR-200a-3p in DF-1 cells using a specific miRNA inhibitor enhanced ARV-induced apoptosis and promoted GRB2 expression, thereby facilitating viral growth within cells. Consistently, inhibition of GRB2 activity through siRNA-mediated knockdown reduced viral titers. Therefore, gga-miR-200a-3p plays a vital antiviral role in the host response to ARV infection by suppressing apoptosis via direct targeting of GRB2 protein. This information enhances our understanding of the mechanisms by which host cells combat against ARV infection through self-encoded small RNA molecules and expands our knowledge regarding the involvement of microRNAs in the host response to pathogenic infections.

Short-chain fatty acids abrogate Japanese encephalitis virus-induced inflammation in microglial cells via miR-200a-3p/ZBTB20/IKβα axis

Japanese encephalitis virus (JEV), a member of the Flaviviridae family, is a leading cause of viral encephalitis in humans. Survivors of this infection often develop lifelong neurological sequelae. Short-chain fatty acids (SCFAs) produced in the gut are vital mediators of the gut-brain axis. We aimed to study microRNA-based mechanisms of SCFAs in an in vitro model of JEV infection. N9 microglial cells were pretreated with SCFA cocktail before JEV infection. Cytokine bead analysis, immunoblotting, and PCR were performed to analyze relevant inflammatory markers. microRNA sequencing was performed using Illumina Hiseq, and bioinformatics tools were used for differentially expressed (DE) miRNAs and weighted gene co-expression network analysis (WGCNA). microRNA mimic/inhibitor experiments and luciferase assay were performed to study miRNA-target interaction. A significant reduction in monocyte chemoattractant protein (MCP1) and tumor necrosis factor alpha (TNFα) along with reduced expression of phospho-nuclear factor kappa B (phospho-NF-κB) was observed in SCFA conditions. Significant attenuation of histone deacetylase activity and protein expression was recorded. miRNA sequencing revealed 160 DE miRNAs in SCFA + JEV-treated cells at 6 h post-infection. WGCNA revealed miR-200a-3p, a hub miRNA significantly upregulated in SCFA conditions. Transcription factor ZBTB20 was bioinformatically predicted and validated as a gene target for miR-200a-3p. Further miRNA mimic/inhibitor assay demonstrated that miR-200-3p regulated ZBTB20 along with Iκβα that possibly dampened NF-κB signal activation downstream.

IMPORTANCE

The gut-brain axis plays a pivotal role in the physiological state of an organism. Gut microbiota-derived metabolites are known to play a role in brain disorders including neuroviral infections. Short-chain fatty acids (SCFAs) appear to quench inflammatory markers in Japanese encephalitis virus-infected microglial cells in vitro. Mechanistically, we demonstrate the interaction between miR-200a-3p and ZBTB20 in regulating the canonical nuclear factor kappa B (NF-κB) signaling pathway via transcriptional regulation of Iκβα. Findings of this study pave the way to a better understanding of SCFA mechanisms that can be used to develop strategies against viral neuroinflammation.

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.

Neuroprotective effects of dantrolene in neurodegenerative disease: Role of inhibition of pathological inflammation

Neurodegenerative diseases (NDs) refer to a group of diseases in which slow, continuous cell death is the main pathogenic event in the nervous system. Most NDs are characterized by cognitive dysfunction or progressive motor dysfunction. Treatments of NDs mainly target alleviating symptoms, and most NDs do not have disease-modifying drugs. The pathogenesis of NDs involves inflammation and apoptosis mediated by mitochondrial dysfunction. Dantrolene, approved by the US Food and Drug Administration, acts as a RyRs antagonist for the treatment of malignant hyperthermia, spasticity, neuroleptic syndrome, ecstasy intoxication and exertional heat stroke with tolerable side effects. Recently, dantrolene has also shown therapeutic effects in some NDs. Its neuroprotective mechanisms include the reduction of excitotoxicity, apoptosis and neuroinflammation. In summary, dantrolene can be considered as a potential therapeutic candidate for NDs.

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.

miR-129-5p as a biomarker for pathology and cognitive decline in Alzheimer's disease

BACKGROUND

Alzheimer's dementia (AD) pathogenesis involves complex mechanisms, including microRNA (miRNA) dysregulation. Integrative network and machine learning analysis of miRNA can provide insights into AD pathology and prognostic/diagnostic biomarkers.

METHODS

We performed co-expression network analysis to identify network modules associated with AD, its neuropathology markers, and cognition using brain tissue miRNA profiles from the Religious Orders Study and Rush Memory and Aging Project (ROS/MAP) (N = 702) as a discovery dataset. We performed association analysis of hub miRNAs with AD, its neuropathology markers, and cognition. After selecting target genes of the hub miRNAs, we performed association analysis of the hub miRNAs with their target genes and then performed pathway-based enrichment analysis. For replication, we performed a consensus miRNA co-expression network analysis using the ROS/MAP dataset and an independent dataset (N = 16) from the Gene Expression Omnibus (GEO). Furthermore, we performed a machine learning approach to assess the performance of hub miRNAs for AD classification.

RESULTS

Network analysis identified a glucose metabolism pathway-enriched module (M3) as significantly associated with AD and cognition. Five hub miRNAs (miR-129-5p, miR-433, miR-1260, miR-200a, and miR-221) of M3 had significant associations with AD clinical and/or pathologic traits, with miR129-5p by far the strongest across all phenotypes. Gene-set enrichment analysis of target genes associated with their corresponding hub miRNAs identified significantly enriched biological pathways including ErbB, AMPK, MAPK, and mTOR signaling pathways. Consensus network analysis identified two AD-associated consensus network modules and two hub miRNAs (miR-129-5p and miR-221). Machine learning analysis showed that the AD classification performance (area under the curve (AUC) = 0.807) of age, sex, and APOE ε4 carrier status was significantly improved by 6.3% with inclusion of five AD-associated hub miRNAs.

CONCLUSIONS

Integrative network and machine learning analysis identified miRNA signatures, especially miR-129-5p, as associated with AD, its neuropathology markers, and cognition, enhancing our understanding of AD pathogenesis and leading to better performance of AD classification as potential diagnostic/prognostic biomarkers.

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.

miR-129-5p as a biomarker for pathology and cognitive decline in Alzheimer's disease

Background

Alzheimer's dementia (AD) pathogenesis involves complex mechanisms, including microRNA (miRNA) dysregulation. Integrative network and machine learning analysis of miRNA can provide insights into AD pathology and prognostic/diagnostic biomarkers.

Methods

We performed co-expression network analysis to identify network modules associated with AD, its neuropathology markers, and cognition using brain tissue miRNA profiles from the Religious Orders Study and Rush Memory and Aging Project (ROS/MAP) (N = 702) as a discovery dataset. We performed association analysis of hub miRNAs with AD, its neuropathology markers, and cognition. After selecting target genes of the hub miRNAs, we performed association analysis of the hub miRNAs with their target genes and then performed pathway-based enrichment analysis. For replication, we performed a consensus miRNA co-expression network analysis using the ROS/MAP dataset and an independent dataset (N = 16) from the Gene Expression Omnibus (GEO). Furthermore, we performed a machine learning approach to assess the performance of hub miRNAs for AD classification.

Results

Network analysis identified a glucose metabolism pathway-enriched module (M3) as significantly associated with AD and cognition. Five hub miRNAs (miR-129-5p, miR-433, miR-1260, miR-200a, and miR-221) of M3 had significant associations with AD clinical and/or pathologic traits, with miR129-5p by far the strongest across all phenotypes. Gene-set enrichment analysis of target genes associated with their corresponding hub miRNAs identified significantly enriched biological pathways including ErbB, AMPK, MAPK, and mTOR signaling pathways. Consensus network analysis identified two AD-associated consensus network modules, and two hub miRNAs (miR-129-5p and miR-221). Machine learning analysis showed that the AD classification performance (area under the curve (AUC) = 0.807) of age, sex, and apoE ε4 carrier status was significantly improved by 6.3% with inclusion of five AD-associated hub miRNAs.

Conclusions

Integrative network and machine learning analysis identified miRNA signatures, especially miR-129-5p, as associated with AD, its neuropathology markers, and cognition, enhancing our understanding of AD pathogenesis and leading to better performance of AD classification as potential diagnostic/prognostic biomarkers.

Discerning the Prospects of miRNAs as a Multi-Target Therapeutic and Diagnostic for Alzheimer's Disease

Although over the last few decades, numerous attempts have been made to halt Alzheimer's disease (AD) progression and mitigate its symptoms, only a few have been proven beneficial. Most medications available, still only cater to the symptoms of the disease rather than fixing the cause at the root level. A novel approach involving the use of miRNAs, which work on the principle of gene silencing, is being explored by scientists. Naturally present miRNAs in the biological system help to regulate various genes than may be implicated in AD-like BACE-1 and APP. One miRNA thus, holds the power to keep a check on several genes, conferring it the ability to be used as a multi-target therapeutic. With aging and the onset of diseased pathology, dysregulation of these miRNAs is observed. This flawed miRNA expression is responsible for the unusual buildup of amyloid proteins, fibrillation of tau proteins in the brain, neuronal death and other hallmarks leading to AD. The use of miRNA mimics and miRNA inhibitors provides an attractive perspective for fixing the upregulation and downregulation of miRNAs that led to abnormal cellular activities. Furthermore, the detection of miRNAs in the CSF and serum of diseased patients might be considered an earlier biomarker for the disease. While most of the therapies designed around AD have not succeeded completely, the targeting of dysregulated miRNAs in AD patients might give a new direction to scholars to develop an effective treatment for Alzheimer's disease.

MicroRNA super-resolution imaging in blood for Alzheimer's disease

We propose a novel blood biomarker detection method that uses miRNA super-resolution imaging to enable the early diagnosis of Alzheimer's disease (AD). Here, we report a singlemolecule detection method for visualizing disease-specific miRNA in tissue from an AD mice model, and peripheral blood mononuclear cells (PBMCs) from AD patients. Using optimized Magnified Analysis of Proteome (MAPs), we confirmed that five miRNAs contribute to neurodegenerative disease in the brain hippocampi of 5XFAD and wild-type mice. We also assessed PBMCs isolated from the whole blood of AD patients and a healthy control group, and subsequently analyzed those samples using miRNA super-resolution imaging. We detected more miR-200a-3p expression in the cornu ammonis 1 and dentate gyrus regions of 3 month-old 5XFAD mice than in wild-type mice. Additionally, miRNA super-resolution imaging of blood provides AD diagnosis platform for studying miRNA regulation inside cells at the single molecule level. Our results present a potential liquid biopsy method that could improve the diagnosis of early stage AD and other diseases. [BMB Reports 2023; 56(3): 190-195].

miRNAs and Stem Cells as Promising Diagnostic and Therapeutic Targets for Alzheimer's Disease

Alzheimer's disease (AD) is a cumulative progressive neurodegenerative disease characterized mainly by impairment in cognitive functions accompanied by memory loss, disturbance in behavior and personality, and difficulties in learning. Although the main causes of AD pathogenesis are not fully understood yet, amyloid-β peptides and tau proteins are supposed to be responsible for AD onset and pathogenesis. Various demographic, genetic, and environmental risk factors are involved in AD onset and pathogenesis such as age, gender, several genes, lipids, malnutrition, and poor diet. Significant changes were observed in microRNA (miRNA) levels between normal and AD cases giving hope for a diagnostic procedure for AD through a simple blood test. As yet, only two classes of AD therapeutic drugs are approved by FDA. They are classified as acetylcholinesterase inhibitors and N-methyl-D-aspartate antagonists (NMDA). Unfortunately, they can only treat the symptoms but cannot cure AD or stop its progression. New therapeutic approaches were developed for AD treatment including acitretin due to its ability to cross blood-brain barrier in the brain of rats and mice and induce the expression of ADAM 10 gene, the α-secretase of human amyloid-β protein precursor, stimulating the non-amyloidogenic pathway for amyloid-β protein precursor processing resulting in amyloid-β reduction. Also stem cells may have a crucial role in AD treatment as they can improve cognitive functions and memory in AD rats through regeneration of damaged neurons. This review spotlights on promising diagnostic techniques such as miRNAs and therapeutic approaches such as acitretin and/or stem cells keeping in consideration AD pathogenesis, stages, symptoms, and risk factors.

GH deficiency confers protective advantages against Alzheimer's disease through rescued miRNA expression profile in APP/PS1 mice

Alzheimer's disease (AD) is the most common form of dementia, affecting approximately 6.5 million Americans age 65 or older. AD is characterized by increased cognitive impairment and treatment options available provide minimal disease attenuation. Additionally, diagnostic methods for AD are not conclusive with definitive diagnoses requiring postmortem brain evaluations. Therefore, miRNAs, a class of small, non-coding RNAs, have garnered attention for their ability to regulate a variety of mRNAs and their potential to serve as both therapeutic targets and biomarkers of AD. Several miRNAs have already been implicated with AD and have been found to directly target genes associated with AD pathology. The APP/PS1 mice is an AD model that expresses the human mutated form of the amyloid precursor protein (APP) and presenilin-1 (PS1) genes. In a previous study, it was identified that crossing long-living growth hormone (GH)-deficient Ames dwarf (df/df) mice with APP/PS1 mice provided protection from AD through a reduction in IGF-1, amyloid-β (Aβ) deposition, and gliosis. Hence, we hypothesized that changes in the expression of miRNAs associated with AD mediated such benefits. To test this hypothesis, we sequenced miRNAs in hippocampi of df/df, wild type (+ / +), df/ + /APP/PS1 (phenotypically normal APP/PS1), and df/df/APP/PS1 mice. Results of this study demonstrated significantly upregulated and downregulated miRNAs between df/df/APP/PS1 and df/ + /APP/PS1 mice that suggest the df/df mutation provides protection from AD progression. Additionally, changes in miRNA expression with age were identified in both df/df and wild-type mice as well as df/df/APP/PS1 and APP/PS1 mice, with predictive functional roles in the Pi3k-AKT/mTOR/FOXO pathways potentially contributing to disease pathogenesis.

Neuroprotective Effects of the Psychoactive Compound Biatractylolide (BD) in Alzheimer's Disease

Mitochondria play a central role in the survival or death of neuronal cells, and they are regulators of energy metabolism and cell death pathways. Many studies support the role of mitochondrial dysfunction and oxidative damage in the pathogenesis of Alzheimer's disease. Biatractylolide (BD) is a kind of internal symmetry double sesquiterpene novel ester compound isolated from the Chinese medicinal plant Baizhu, has neuroprotective effects in Alzheimer's disease. We developed a systematic pharmacological model based on chemical pharmacokinetic and pharmacological data to identify potential compounds and targets of Baizhu. The neuroprotective effects of BD in PC12 (rat adrenal pheochromocytoma cells) and SH-SY5Y (human bone marrow neuroblastoma cells) were evaluated by in vitro experiments. Based on the predicted results, we selected 18 active compounds, which were associated with 20 potential targets and 22 signaling pathways. Compound-target, target-disease and target-pathway networks were constructed using Cytoscape 3.2.1. And verified by in vitro experiments that BD could inhibit Aβ by reducing oxidative stress and decreasing CytC release induced mPTP opening. This study provides a theoretical basis for the development of BD as an anti-Alzheimer's disease drug.

Long non-coding RNA MALAT1 protects against Aβ1-42 induced toxicity by regulating the expression of receptor tyrosine kinase EPHA2 via quenching miR-200a/26a/26b in Alzheimer's disease

Altered expressions of Receptor Tyrosine Kinases (RTK) and non-coding (nc) RNAs are known to regulate the pathophysiology of Alzheimer's disease (AD). However, specific understanding of the roles played, especially the mechanistic and functional roles, by long ncRNAs in AD is still elusive. Using mouse tissue qPCR assays we observe changes in the expression levels of 41 lncRNAs in AD mice of which only 7 genes happen to have both human orthologs and AD associations. Post validation of these 7 human lncRNA genes, MEG3 and MALAT1 shows consistent and significant decrease in AD cell, animal models and human AD brain tissues, but MALAT1 showed a more pronounced decrease. Using bioinformatics, qRT-PCR, RNA FISH and RIP techniques, we could establish MALAT1 as an interactor and regulator of miRs-200a, -26a and -26b, all of which are naturally elevated in AD. We could further show that these miRNAs target the RTK EPHA2 and several of its downstream effectors. Expectedly EPHA2 over expression protects against Aβ1-42 induced cytotoxicity. Transiently knocking down MALAT1 validates these unique regulatory facets of AD at the miRNA and protein levels. Although the idea of sponging of miRNAs by lncRNAs in other pathologies is gradually gaining credibility, this novel MALAT1- miR-200a/26a/26b - EPHA2 regulation mechanism in the context of AD pathophysiology promises to become a significant strategy in controlling the disease.

Revisiting the miR-200 Family: A Clan of Five Siblings with Essential Roles in Development and Disease

Over two decades of studies on small noncoding RNA molecules illustrate the significance of microRNAs (miRNAs/miRs) in controlling multiple physiological and pathological functions through post-transcriptional and spatiotemporal gene expression. Among the plethora of miRs that are essential during animal embryonic development, in this review, we elaborate the indispensable role of the miR-200 family (comprising miR-200a, -200b, 200c, -141, and -429) in governing the cellular functions associated with epithelial homeostasis, such as epithelial differentiation and neurogenesis. Additionally, in pathological contexts, miR-200 family members are primarily involved in tumor-suppressive roles, including the reversal of the cancer-associated epithelial–mesenchymal transition dedifferentiation process, and are dysregulated during organ fibrosis. Moreover, recent eminent studies have elucidated the crucial roles of miR-200s in the pathophysiology of multiple neurodegenerative diseases and tissue fibrosis. Lastly, we summarize the key studies that have recognized the potential use of miR-200 members as biomarkers for the diagnosis and prognosis of cancers, elaborating the application of these small biomolecules in aiding early cancer detection and intervention.

Activation of SIRT-1 Signalling in the Prevention of Bipolar Disorder and Related Neurocomplications: Target Activators and Influences on Neurological Dysfunctions

SIRT-1 (silent mating-type information regulation 2 homolog-1) is a protein found in neuronal nuclei, microglia, and astrocyte cells of the brain. It is sometimes referred to as NAD + -dependent deacetylase (nicotinamide adenine dinucleotide). The activation of sirtuins (SIRT-1-7) has been shown to protect against a wide range of disorders, including neurodegenerative and neuropsychiatric disorders. SIRT-1 has gained considerable interest from these families because of its early link to long-life expansion and calorie restriction involvement. SIRT-1 is necessary for gene silencing, cell cycle regulation, fat and glucose metabolism, oxidative stress, ageing, and memory formation. In this review, we investigate the role of SIRT-1 downregulation in the progression of bipolar disorder (BD) and neurological abnormalities, as well as related neurological alterations such as genetic dysfunction, neurotransmitter imbalance, oxidative stress-induced apoptosis, and mitochondrial dysfunction. BD is a psychiatric disease distinguished by extreme mood fluctuations that range from depressive lows to manic highs. BD is a complicated disorder with numerous clinical signs and neurocomplications that produce significant behavioural problems. SIRT-1 deficiency in the brain has been demonstrated to affect the activity of its transcription factors and molecular changes, including genetic defects. SIRT-1 is now being studied as a potential therapeutic target for a range of brain disorders. A recent study also found that activating SIRT-1 signalling performs a protective effect in avoiding depression and mania-like behaviours. Furthermore, this review investigates the potential mechanisms by which SIRT-1 regulates neuronal transmission and neurogenesis. As a result of our review, we revealed that SIRT-1 activators have neuroprotective potential in BD and related neurological dysfunctions.

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.

Sirtuins at the Crossroads between Mitochondrial Quality Control and Neurodegenerative Diseases: Structure, Regulation, Modifications, and Modulators

Sirtuins (SIRT1-SIRT7), a family of nicotinamide adenine dinucleotide (NAD⁺)-dependent enzymes, are key regulators of life span and metabolism. In addition to acting as deacetylates, some sirtuins have the properties of deacylase, decrotonylase, adenosine diphosphate (ADP)-ribosyltransferase, lipoamidase, desuccinylase, demalonylase, deglutarylase, and demyristolyase. Mitochondrial dysfunction occurs early on and acts causally in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Sirtuins are implicated in the regulation of mitochondrial quality control, which is highly associated with the pathogenesis of neurodegenerative diseases. There is growing evidence indicating that sirtuins are promising and well-documented molecular targets for the treatment of mitochondrial dysfunction and neurodegenerative disorders by regulating mitochondrial quality control, including mitochondrial biogenesis, mitophagy, mitochondrial fission/fusion dynamics, and mitochondrial unfolded protein responses (mtUPR). Therefore, elucidation of the molecular etiology of sirtuin-mediated mitochondrial quality control points to new prospects for the treatment of neurodegenerative diseases. However, the mechanisms underlying sirtuin-mediated mitochondrial quality control remain obscure. In this review, we update and summarize the current understanding of the structure, function, and regulation of sirtuins with an emphasis on the cumulative and putative effects of sirtuins on mitochondrial biology and neurodegenerative diseases, particularly their roles in mitochondrial quality control. In addition, we outline the potential therapeutic applications for neurodegenerative diseases of targeting sirtuin-mediated mitochondrial quality control through exercise training, calorie restriction, and sirtuin modulators in neurodegenerative diseases.

miR-200a-3p Regulates PRKACB and Participates in Aluminium-Induced Tau Phosphorylation in PC12 Cells

Aluminium (Al) is an environmental neurotoxin that humans are widely exposed to, but the molecular mechanism of its toxic effects is not fully understood. Many studies have shown that exposure to Al can cause abnormal phosphorylation of the tau protein that is believed as one of pathological features of Alzheimer's disease. Increasing evidence indicates that microRNAs (miRNAs) may be involved in the pathological processes of neurodegenerative diseases and are potential regulatory factors for related target genes. Phosphorylation at Ser-133 of cAMP response element-binding protein (CREB) is one of the major pathways of CREB activation, and phosphorylation at this site is controlled by protein kinase A (PKA). The catalytic subunit of PKA, cAMP-dependent protein kinase catalytic subunit beta (PRKACB), phosphorylates CREB. The target gene prediction software TargetScan showed that PRKACB was one of the target mRNAs of miR-200a-3p. The purpose of this study was to investigate whether miR-200a-3p regulates the PKA/CREB pathway by targeting PRKACB and leads to abnormal phosphorylation of the tau protein in nerve cells. The results showed that Al exposure increased the expression level of miR-200a-3p, and miR-200a-3p increased the expression of targeted downregulated PRKACB, and then decreased the PKA/CREB signalling pathway activity, leading to abnormal hyperphosphorylation of tau.

MiR-29c-3p May Promote the Progression of Alzheimer's Disease through BACE1

The aim of this study was to explore the specific role of miR-29c-3p in Alzheimer's disease (AD). Animal models of AD were established by injecting streptozotocin (STZ) into mice through the lateral ventricle, while cell models of AD were induced by 10 μM β-amyloid (Aβ). We detected miR-29c-3p and β-site amyloid precursor protein cleaving enzyme 1 (BACE1) contents and measured AD cell proliferation and apoptosis. A low miR-29c-3p level and a high BACE1 level were detected in the brain tissue of AD animal models and AD cell models. Aβ-processed cells had markedly lower proliferation activity, higher apoptosis, increased phosphorylation of tau protein was over phosphorylated, but the overexpression of miR-29c-3p or the silencing of BACE1 significantly enhanced the cell proliferation activity and reduced cell apoptosis by regulating the contents of related proteins. Inhibition of miR-29c-3p or overexpression of BACE1 aggravated Aβ-induced side effects. We used Targetscan7.2 to predict the downstream target genes of miR-29c-3p. Then, we detected that there were target binding sites between miR-29c-3p and BACE1. The rescue experiment identified BACE1 as a functional target for miR-29c-3p. AD leads to decreased miR-29c-3p level and increased BACE1 level. MiR-29c-3p has specific binding sites with the 3′-untranslated region (3′-UTR) of BACE1 and thus negatively regulates the BACE1 level, thereby affecting the progression of AD.

Multifaced role of protein deacetylase sirtuins in neurodegenerative disease

Sirtuins, a class III histone/protein deacetylase, is a central regulator of metabolic function and cellular stress response. This plays a pivotal role in the pathogenesis and progression of diseases such as cancer, neurodegeneration, metabolic syndromes, and cardiovascular disease. Sirtuins regulate biological and cellular processes, for instance, mitochondrial biogenesis, lipid and fatty acid oxidation, oxidative stress, gene transcriptional activity, apoptosis, inflammatory response, DNA repair mechanism, and autophagic cell degradation, which are known components for the progression of the neurodegenerative diseases (NDDs). Emerging evidence suggests that sirtuins are the useful molecular targets against NDDs like, Alzheimer's Disease (AD), Parkinson's Disease (PD), Huntington's Disease (HD), and Amyotrophic Lateral Sclerosis (ALS). However, the exact mechanism of neuroprotection mediated through sirtuins remains unsettled. The manipulation of sirtuins activity with its modulators, calorie restriction (CR), and micro RNAs (miR) is a novel therapeutic approach for the treatment of NDDs. Herein, we reviewed the current putative therapeutic role of sirtuins in regulating synaptic plasticity and cognitive functions, which are mediated through the different molecular phenomenon to prevent neurodegeneration. We also explained the implications of sirtuin modulators, and miR based therapies for the treatment of life-threatening NDDs.

The neurobiology of non-coding RNAs and Alzheimer's disease pathogenesis: Pathways, mechanisms and translational opportunities

In the past two decades, advances in sequencing technology and analysis of the human and mouse genome have led to the discovery of many non-protein-coding RNAs (ncRNAs) including: microRNA, small-interfering RNAs, piwi-associated small RNAs, transfer RNA-derived small RNAs, long-non-coding RNAs and circular RNAs. Compared with healthy controls, levels of some ncRNAs are significantly altered in the central nervous system and blood of patients affected by neurodegenerative disorders like Alzheimer's disease (AD). Although the mechanisms are still not fully elucidated, studies have revealed that these highly conserved ncRNAs are important modulators of gene expression, amyloid-β production, tau phosphorylation, inflammation, synaptic plasticity and neuronal survival, all features considered central to AD pathogenesis. Despite considerable difficulties due to their large heterogeneity, and the complexity of their regulatory pathways, research in this rapidly growing field suggests that ncRNAs hold great potential as biomarkers and therapeutic targets against AD. Herein, we summarize the current knowledge regarding the neurobiology of ncRNA in the context of AD pathophysiology.

MicroRNAs as Potential Orchestrators of Alzheimer's Disease-Related Pathologies: Insights on Current Status and Future Possibilities

Alzheimer's disease (AD) is a progressive and deleterious neurodegenerative disease, strongly affecting the cognitive functions and memory of seniors worldwide. Around 58% of the affected patients live in low and middle-income countries, with estimates of increasing deaths caused by AD in the coming decade. AD is a multifactor pathology. Mitochondrial function declines in AD brain and is currently emerging as a hallmark of this disease. It has been considered as one of the intracellular processes severely compromised in AD. Many mitochondrial parameters decline already during aging; mitochondrial efficiency for energy production, reactive oxygen species (ROS) metabolism and the de novo synthesis of pyrimidines, to reach an extensive functional failure, concomitant with the onset of neurodegenerative conditions. Besides its impact on cognitive functions, AD is characterized by loss of synapses, extracellular amyloid plaques composed of the amyloid-β peptide (Aβ), and intracellular aggregates of hyperphosphorylated Tau protein, accompanied by drastic sleep disorders, sensory function alterations and pain sensitization. Unfortunately, till date, effective management of AD-related disorders and early, non-invasive AD diagnostic markers are yet to be found. MicroRNAs (miRNAs) are small non-coding nucleic acids that regulate key signaling pathway(s) in various disease conditions. About 70% of experimentally detectable miRNAs are expressed in the brain where they regulate neurite outgrowth, dendritic spine morphology, and synaptic plasticity. Increasing studies suggest that miRNAs are intimately involved in synaptic function and specific signals during memory formation. This has been the pivotal key for considering miRNAs crucial molecules to be studied in AD. MicroRNAs dysfunctions are increasingly acknowledged as a pivotal contributor in AD via deregulating genes involved in AD pathogenesis. Moreover, miRNAs have been proved to control pain sensitization processes and regulate circadian clock system that affects the sleep process. Interestingly, the differential expression of miRNA panels implies their emerging potential as diagnostic AD biomarkers. In this review, we will present an updated analysis of miRNAs role in regulating signaling processes that are involved in AD-related pathologies. We will discuss the current challenges against wider use of miRNAs and the future promising capabilities of miRNAs as diagnostic and therapeutic means for better management of AD.

A Review of miRNAs as Biomarkers and Effect of Dietary Modulation in Obesity Associated Cognitive Decline and Neurodegenerative Disorders

There has been a progressive increase in the prevalence of obesity and its comorbidities such as type 2 diabetes and cardiovascular diseases worldwide. Recent studies have suggested that the crosstalk between adipose tissue and central nervous system (CNS), through cellular mediators and signaling pathways, may causally link obesity with cognitive decline and give rise to neurodegenerative disorders. Several mechanisms have been proposed in obesity, including inflammation, oxidative stress, insulin resistance, altered lipid and cholesterol homeostasis, which may result in neuroinflammation, altered brain insulin signaling, amyloid-beta (Aβ) deposition and neuronal cell death. Since obesity is associated with functional and morphological alterations in the adipose tissues, the resulting peripheral immune response augments the development and progression of cognitive decline and increases susceptibility of neurodegenerative disorders, such as Alzheimer's Disease (AD) and Parkinson's Disease (PD). Studies have also elucidated an important role of high fat diet in the exacerbation of these clinical conditions. However, the underlying factors that propel and sustain this obesity associated cognitive decline and neurodegeneration, remains highly elusive. Moreover, the mechanisms linking these phenomena are not well-understood. The cumulative line of evidence have demonstrated an important role of microRNAs (miRNAs), a class of small non-coding RNAs that regulate gene expression and transcriptional changes, as biomarkers of pathophysiological conditions. Despite the lack of utility in current clinical practices, miRNAs have been shown to be highly specific and sensitive to the clinical condition being studied. Based on these observations, this review aims to assess the role of several miRNAs and aim to elucidate underlying mechanisms that link obesity with cognitive decline and neurodegenerative disorders. Furthermore, this review will also provide evidence for the effect of dietary modulation which can potentially ameliorate cognitive decline and neurodegenerative diseases associated with obesity.

5,6,7,4'-Tetramethoxyflavanone attenuates NADPH oxidase 1/4 and promotes sirtuin-1 to inhibit cell stress, senescence and apoptosis in Aß25-35-mediated SK-N-SH dysfunction

Amyloidogenesis is a fundamental step of amyloid beta (Aβ) generation-induced toxicity that is commonly reported to disrupt neuronal circuits, function and survival in Alzheimer's disease (AD). The neuroprotective effect of 5,6,7,4'-tetramethoxyflavanone (TMF) from Chormolaela odorata extract on brain degeneration and amyloidogenesis has previously been demonstrated. However, the mechanistic evidence for TMF's effects is still unclear. In this study, we evaluated the neuroprotective effect of TMF in Aβ_25-35-induced toxicity in SK-N-SH neuroblastoma cells. Herein, we demonstrated that TMF exhibited potent antioxidant activity and significantly increased cell viability and decreased ROS production in a dose-dependent manner. Moreover, TMF reversed the effect of Aβ_25-35, which caused energy deprivation and apoptosis, by decreasing the ratio of Bax/Bcl-x_L and reducing mitochondrial membrane potential (Δψ_m), caspase-3 expression, apoptotic cells, and attenuating glucose transporter (Glut-3) expression. In addition, TMF protected against Aβ_25-35-induced cellular senescence by attenuating β-galactosidase, p-21 and p-53 expression and promoted the expression of Sirt-1 and p-Rb. In addition, the effects of TMF on Aβ_25-35 toxicity were related to the upregulation of phase II antioxidant and nuclear factor erythroid 2-related factor-2 (Nrf2) signaling, including superoxide dismutase (SOD), heme oxygenase (HO)-1, and nuclear translocation of Nrf2. Finally, we also found that TMF attenuated Aβ_25-35-reduced synaptic plasticity by increasing the expression of synaptophysin and PSD-95, which was correlated with a decrease in acetylcholine esterase (AChE). Importantly, we found that the protective effects of TMF on Aβ_25-35 were bidirectional, including marked inhibition of NADPH oxidase (NOX)-4 activity and partial activation of Sirt-1, which occurred prior to a reduction in the negative responses. Therefore, TMF may be useful for treating Aβ toxicity in AD.

Systems pharmacology approach uncovers the therapeutic mechanism of medicarpin against scopolamine-induced memory loss

BACKGROUND

Medicarpin is a natural pterocarpan-type phytoalexin widely distributed in many traditional Chinese medicines, such as Astragali Radix. A previous study showed that Astragali Radix demonstrated promising protective effects in neurons. However, there is no reported study on the neuroprotective function and the underlying mechanism of Medicarpin.

PURPOSE

This study aimed to demonstrate the neuroprotective effect of Medicarpin on Alzheimer's disease (AD) and explore the therapeutic mechanisms.

METHOD

First, we carried out animal behavioral tests and biochemical analysis to assess the anti-AD potential of Medicarpin for ameliorating spatial learning and memory and modulating cholinergic metabolism in scopolamine-induced amnesic mice. Subsequently, network proximity prediction was used to measure the network distance between the Medicarpin target network and AD-related endophenotype module. We identified Medicarpin-regulated AD pathological processes and highlighted the key disease targets via network analysis. Finally, experimental approaches including Nissl staining and Western blotting were conducted to validate our network-based findings.

RESULT

In this study, we first observed that Medicarpin can ameliorate cognitive and memory dysfunction and significantly modulate cholinergic metabolism in scopolamine-induced amnesic mice. We then proposed an endophenotype network-based framework to comprehensively explore the AD therapeutic mechanisms of Medicarpin by integrating 25 AD-related endophenotype modules, gold-standard AD seed genes, an experimentally validated drug-target network of Medicarpin, and a global human protein-protein interactome. In silico prediction revealed that the effect of Medicarpin is highly relevant to neuronal apoptosis and synaptic plasticity, which was validated by experimental assays. Network analysis and Western blotting further identified two key targets, GSK-3β and MAPK14 (p38), in the AD-related protein regulatory network, which play key roles in the regulation of neuronal apoptosis and synaptic plasticity by Medicarpin.

CONCLUSIONS

This study presented a powerful endophenotype network-based strategy to explore the mechanisms of action (MOAs) of new AD therapeutics, and first identified Medicarpin as a potential anti-AD candidate by targeting multiple pathways.

Apoptosis and its therapeutic implications in neurodegenerative diseases

Neurodegenerative disorders are characterized by progressive loss of particular populations of neurons. Apoptosis has been implicated in the pathogenesis of neurodegenerative diseases, including Parkinson disease, Alzheimer disease, Huntington disease, and amyotrophic lateral sclerosis. In this review, we focus on the existing notions relevant to comprehending the apoptotic death process, including the morphological features, mediators and regulators of cellular apoptosis. We also highlight the evidence of neuronal apoptotic death in Parkinson disease, Alzheimer disease, Huntington disease, and amyotrophic lateral sclerosis. Additionally, we present evidence of potential therapeutic agents that could modify the apoptotic pathway in the aforementioned neurodegenerative diseases and delay disease progression. Finally, we review the clinical trials that were conducted to evaluate the use of anti-apoptotic drugs in the treatment of the aforementioned neurodegenerative diseases, in order to highlight the essential need for early detection and intervention of neurodegenerative diseases in humans.

miR-200a-3p Attenuates Coronary Microembolization-Induced Myocardial Injury in Rats by Inhibiting TXNIP/NLRP3-Mediated Cardiomyocyte Pyroptosis

Coronary microembolization (CME) commonly develops as a complication after percutaneous coronary intervention (PCI), and associated inflammation is a leading driver of myocardial damage. Cardiomyocyte loss in the context of ischemic myocardial disease has been linked to inflammatory pyroptotic cell death. Additionally, miR-200a-3p dysregulation has been linked to myocardial ischemia-reperfusion and many other pathological conditions. However, how miR-200a-3p impacts cardiomyocyte pyroptosis in the context of CME remains to be assessed. Herein, a rat model of CME was established via the injection of microembolic spheres into the left ventricle. When myocardial tissue samples from these rats were analyzed, miR-200a-3p levels were markedly decreased, whereas thioredoxin-interacting protein (TXNIP) levels were increased. The ability of miR-200a-3p to directly target TXNIP and to control its expression was confirmed via dual-luciferase reporter assay. Adeno-associated virus serotype 9-pre-miR-200a-3p (AAV-miR-200a-3p) construct transfection was then employed as a means of upregulating this miRNA in CME model rats. Subsequent assays, including echocardiography, enzyme-linked immunosorbent assays (ELISAs), hematoxylin-eosin (H&E) staining, hematoxylin-basic fuchsin-picric acid (HBFP) staining, TdT-mediated dUTP nick-end labeling (TUNEL) staining, immunofluorescence staining, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blotting revealed that miR-200a-3p overexpression inhibited cardiomyocyte pyroptosis and alleviated CME-induced myocardial injury by inhibiting the TXNIP/NOD-like receptor family pyrin domain-containing 3 (NLRP3) pathway. The ability of miR-200a-3p to protect against CME-induced myocardial injury thus highlights a novel approach to preventing or treating such myocardial damage in clinical settings.

Differential expression of microRNAs associated with neurodegenerative diseases and diabetic nephropathy in protein l-isoaspartyl methyltransferase-deficient mice

Protein l-isoaspartyl methyltransferase (PIMT/PCMT1), an enzyme repairing isoaspartate residues in peptides and proteins that result from the spontaneous decomposition of normal l-aspartyl and l-asparaginyl residues during aging, has been revealed to be involved in neurodegenerative diseases (NDDs) and diabetes. However, the molecular mechanisms for a putative association of PIMT dysfunction with these diseases have not been clarified. Our study aimed to identify differentially expressed microRNAs (miRNAs) in the brain and kidneys of PIMT-deficient mice and uncover the epigenetic mechanism of PIMT-involved NDDs and diabetic nephropathy (DN). Differentially expressed miRNAs by sequencing underwent target prediction and enrichment analysis in the brain and kidney of PIMT knockout (KO) mice and age-matched wild-type (WT) littermates. Sequence analysis revealed 40 differentially expressed miRNAs in the PIMT KO mouse brain including 25 upregulated miRNAs and 15 downregulated miRNAs. In the PIMT KO mouse kidney, there were 80 differentially expressed miRNAs including 40 upregulated miRNAs and 40 downregulated miRNAs. Enrichment analysis and a systematic literature review of differentially expressed miRNAs indicated the involvement of PIMT deficiency in the pathogenesis in NDDs and DN. Some overlapped differentially expressed miRNAs between the brain and kidney were quantitatively assessed in the brain, kidney, and serum-derived exosomes, respectively. Despite being preliminary, these results may aid in investigating the pathological hallmarks and identify the potential therapeutic targets and biomarkers for PIMT dysfunction-related NDDs and DN.

Protective Role of microRNA-200a in Diabetic Retinopathy Through Downregulation of PDLIM1

Background

Diabetic retinopathy (DR) is a most common microvascular complication and regarded as the leading cause of blindness in the working age population. The involvement of miR-200a in various disorders has become recognized, and the objective of this study was to identify the protective effect of miR-200a in the development of DR.

Methods

The contents of miR-200a and its potential target gene, PDZ and LIM domain protein 1 (PDLIM1), were detected in both in-vivo and in-vitro DR models. Retinal leakage and inflammatory factor concentrations were detected after vitreous injections of miR-200a/PDLIM1 vectors in mice. The cellular viability, apoptosis and cellular migration were investigated using trypan blue staining, flow cytometry and transwell assay with human retinal microvascular endothelial cells (HRMECs). Besides, the prediction and confirmation of miR-200a targeting PDLIM1 were conducted with bioinformation analyses and dual-luciferase reporter assay.

Results

Lower miR-200a and higher PDLIM1 levels were detected in both in-vivo and in-vitro DR models. Besides, it was found that miR-200a treatment would significantly inhibit retinal permeability and inflammatory factors. Through targeting PDLIM1, it was found that miR-200a could improve cellular viability, remit apoptotic status and reduce cellular migration significantly in high glucose-treated HRMECs.

Conclusion

Our results demonstrated that miR-200a could be used as a potential therapy target through down-regulating PDLIM1 in DR.

Interplay of RNA-Binding Proteins and microRNAs in Neurodegenerative Diseases

The number of patients with neurodegenerative diseases (NDs) is increasing, along with the growing number of older adults. This escalation threatens to create a medical and social crisis. NDs include a large spectrum of heterogeneous and multifactorial pathologies, such as amyotrophic lateral sclerosis, frontotemporal dementia, Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and multiple system atrophy, and the formation of inclusion bodies resulting from protein misfolding and aggregation is a hallmark of these disorders. The proteinaceous components of the pathological inclusions include several RNA-binding proteins (RBPs), which play important roles in splicing, stability, transcription and translation. In addition, RBPs were shown to play a critical role in regulating miRNA biogenesis and metabolism. The dysfunction of both RBPs and miRNAs is often observed in several NDs. Thus, the data about the interplay among RBPs and miRNAs and their cooperation in brain functions would be important to know for better understanding NDs and the development of effective therapeutics. In this review, we focused on the connection between miRNAs, RBPs and neurodegenerative diseases.

Molecular imaging of NAD+ -dependent deacetylase SIRT1 in the brain

INTRODUCTION

Aging is an inevitable physiological process and the biggest risk factor of Alzheimer's disease (AD). Developing an imaging tracer to visualize aging-related changes in the brain may provide a useful biomarker in elucidating neuroanatomical mechanisms of AD.

METHODS

We developed and characterized a new tracer that can be used to visualize SIRT1 in brains related to aging and AD by positron emission tomography imaging.

RESULTS

The SIRT1 tracer displayed desirable brain uptake and selectivity, as well as stable metabolism and proper kinetics and distribution in rodent and nonhuman primate brains. This new tracer was further validated by visualizing SIRT1 in brains of AD transgenic mice, compared to nontransgenic animals.

DISCUSSION

Our SIRT1 tracer not only enables, for the first time, the demonstration of SIRT1 in animal brains, but also allows visualization and recapitulation of AD-related SIRT1 neuropathological changes in animal brains.

Deregulated lncRNA MAGI2-AS3 in Alzheimer's disease attenuates amyloid-β induced neurotoxicity and neuroinflammation by sponging miR-374b-5p

BACKGROUND

Alzheimer's disease (AD) is a common neurodegenerative disease, which is characterized by aberrant accumulation of amyloid-β (Aβ) and neuroinflammation. The purpose of this study was to explore the regulatory effects of long non-coding RNA (lncRNA) MAGI2-AS3 and microRNA-374b-5p (miR-374b-5p) on Aβ-induced neurotoxicity and neuroinflammation, as well as the relationship between MAGI2-AS3 and miR-374b-5p in AD patients.

METHODS

A luciferase reporter assay was used to analyze the interaction between MAGI2-AS3 and miR-374b-5p and between miR-374b-5p and beta-site amyloid precursor protein cleaving enzyme 1 (BACE1). SH-SY5Y and BV2 cells treated with Aβ25-35 were used to mimic neuronal injury and neuroinflammation in AD pathogenesis. Cell viability was evaluated using a MTT assay, and pro-inflammatory cytokine levels were measured using ELISA kits. MAGI2-AS3 and miR-374b-5p expression was examined using quantitative real-time PCR.

RESULTS

BACE1 served as a target gene of miR-374b-5p, and MAGI2-AS3 could sponge miR-374b-5p. The expression of MAGI2-AS3 was increased, and miR-374b-5p was decreased in both SH-SY5Y and BV2 cells exposed to Aβ25-35. MAGI2-AS3 reduction enhanced neuronal viability and attenuated neuroinflammation in AD cell models, and miR-374b-5p overexpression led to same effects, but miR-374b-5p inhibition reversed these effects. Serum MAGI2-AS3 and miR-374b-5p levels in AD patients were negatively correlated and correlated with disease severity.

CONCLUSION

The findings indicated that the MAGI2-AS3/miR-374b-5p axis regulates Aβ-induced neurotoxicity in SH-SY5Y cells and neuroinflammation in BV2 cells. The MAGI2-AS3/miR-374b-5p axis may provide novel biomarkers and therapeutic targets for AD.

MiR-485-3p serves as a biomarker and therapeutic target of Alzheimer's disease via regulating neuronal cell viability and neuroinflammation by targeting AKT3

BACKGROUND

Numerous microRNAs (miRNAs) have been identified as functional molecules in Alzheimer's disease (AD) pathogenesis. This study aimed to investigate the diagnostic value of microRNA-485-3p (miR-485-3p) in AD patients, evaluate the effect of miR-485-3p on neuronal viability and neuroinflammation, as well as the underlying molecular mechanisms.

METHODS

Quantitative Real-Time PCR was used to estimate expression of miR-485-3p and AKT3. A ROC analysis was used to evaluate the diagnostic value of miR-485-3p. The correlation of miR-485-3p with patients' MMSE score and inflammatory response was analyzed. Using Aβ-treated SH-SY5Y and BV2 cells models, the effects of miR-485-3p on neuronal proliferation, apoptosis, and neuroinflammation were explored. A luciferase reporter assay was used to confirm the target gene of miR-485-3p in both SH-SY5Y and BV2 cells.

RESULTS

Serum miR-485-3p expression was significantly upregulated in AD patients and cell models, which had a high diagnostic accuracy and correlated with MMSE score and inflammatory response in AD patients. The knockdown of miR-485-3p in SH-SY5Y and BV2 cells was found to significantly reverse the effect of Aβ treatment on neuronal viability and neuroinflammation. AKT3 was determined as a target of miR-485-3p, which might mediate the biological function of miR-485-3p in AD pathogenesis.

CONCLUSION

All the data indicated that increased serum miR-485-3p serves as a diagnostic biomarker in AD patients, and knockdown of miR-485-3p exerts a neuroprotective role by improving neuronal viability and weakening neuroinflammation, which may be mediated by AKT3. This study may provide a novel biomarker and therapeutic target for AD therapy.

Clinical significance of miR-433 in the diagnosis of Alzheimer's disease and its effect on Aβ-induced neurotoxicity by regulating JAK2

BACKGROUND

Numerous microRNAs (miRNAs) have been investigated in the progression of Alzheimer's disease (AD). The purpose of this study was to analyze the expression of miR-433 and its diagnostic value in patients with AD, and to explore the neuroprotective effect of miR-433 in amyloid β (Aβ)-treated SH-SY5Y and SK-N-SH cells.

METHODS

AD patients and AD cell model that established by Aβ treatment were used in this study. Quantitative real-time PCR was used to measure the expression of miR-433. The diagnostic value of miR-433 was evaluated using the receiver operating characteristic analysis. MTT assay was used to examine the viability of Aβ-treated SH-SY5Y and SK-N-SH cells. Bioinformatics and luciferase activity analyses were used to confirm the target gene that might be involved in the mechanisms of miR-433 in AD.

RESULTS

Expression levels of miR-433 were decreased in AD patients and cells compared with the corresponding controls. The decreased miR-433 expression levels in serum and cerebrospinal fluid (CS) were positively correlated with MMSE scores and had relatively high diagnostic accuracy in AD patients. The gain-of-function experiments found that the overexpression of miR-433 could rescue the Aβ-induced inhibition in neuronal viability in SH-SY5Y and SK-N-SH cells. The luciferase activity results showed that JAK2 was a target gene of miR-433 in neuronal cells.

CONCLUSION

All the data of this study showed that miR-433 serves as a candidate diagnostic biomarker for AD patients, and may have the potential as a novel therapeutic target by ameliorating Aβ-induced neurotoxicity.

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.

Regulatory roles of the miR-200 family in neurodegenerative diseases

Neurodegenerative diseases are chronic and progressive disorders which are not effectively treated through adopting conventional therapies. For this unmet medical need, alternative therapeutic methods including gene-based therapies are emphasized. MicroRNAs (miRNAs) are small non-coding RNAs which can regulate gene expression at the post-transcriptional level. In recent years, dysregulated miRNAs have been indicated to be implicated in the occurrence and development of neurodegenerative diseases. They are investigated as candidates for diagnostic and prognostic biomarkers, as well as therapeutic targets. The miR-200 family consists of miR-200a, -200b, -200c, -141, and -429. Numerous studies have found that miR-200 family members are associated with the pathogenesis of neurodegenerative diseases. It is reported that miR-200 family members are aberrantly expressed in several neurodegenerative diseases, participating in various cellular processes including beta-amyloid (Aβ) secretion, alpha-synuclein aggregation and DNA repair, etc. In the present review, we summarize the recent progress in the roles of miR-200 family in neurodegenerative diseases.

Overexpression of miR‑200a‑3p promoted inflammation in sepsis‑induced brain injury through ROS‑induced NLRP3

Sepsis, a systemic inflammatory response syndrome induced by infection, is a common complication of trauma, burns, postoperative infection and critical disease, and is characterized by an acute onset and high fatality rate. The aim of the present study was to explore the possible molecular mechanisms of microRNA-200a-3p (miRNA-200a-3p) on inflammation during sepsis. Reverse transcription-quantitative PCR and gene microarray were used to measure the expression of miRNA-200a-3p. Tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and IL-18 were searched by ELISA. The related proteins expression was measured using western blotting. The expression of miRNA-200a-3p was markedly higher in the sepsis model when compared with the normal control group. In addition, the expression of miRNA-200a-3p was upregulated by the miRNA-200a-3p plasmid in human brain microvascular endothelial cells treated with lipopolysaccharide, which further induced inflammation via the induction of NLR family pyrin domain containing 3 (NLRP3) and suppression of Kelch like ECH associated protein (Keap)-1/nuclear factor erythroid 2 like 2 (Nrf2)/heme oxygenase (HO)-1. The inhibition of Keap1/Nrf2/HO-1 attenuated the effects of anti-miRNA-200a-3p on inflammation. However, the inhibition of NLRP3 attenuated the effects of miRNA-200a-3p on inflammation. In conclusion, to the best of our knowledge, the results of the present study demonstrated for the first time that overexpression of miRNA-200a-3p promoted inflammation in sepsis-induced brain injury through reactive oxygen species-induced NLRP3.

Analysis of transcription factor- and ncRNA-mediated potential pathogenic gene modules in Alzheimer's disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disease that ranks as the fourth most common cause of death in developed countries. In our study, genes differentially expressed between AD and healthy individuals were identified and used to construct protein-protein interaction (PPI) networks. The AD-related PPI network was used to identify functional modules, and enrichment analysis showed that they were significantly involved in “Alzheimer’s disease”, “apoptosis”, and related pathways. We predicted non-coding RNAs and transcription factors that may regulate the functional modules. The expression of hub genes and transcription factors was validated in an independent data set. The results in this study provide several candidates for further research on mechanisms of AD pathogenesis.

Role of miRNAs in Alzheimer's Disease and Possible Fields of Application

miRNAs (or microRNAs) are a class of single-stranded RNA molecules, responsible for post-transcriptional gene silencing through binding to the coding region as well as 3' and 5' untranslated region of target genes. About 70% of experimentally detectable miRNAs are expressed in the brain and some studies suggest that miRNAs are intimately involved in synaptic function and in specific signals during memory formation. More and more evidence demonstrates the possible involvement of miRNAs in Alzheimer's disease (AD). AD is the most common form of senile dementia, a disease that affects memory and cognitive functions. It is a neurodegenerative disorder characterized by loss of synapses, extracellular amyloid plaques composed of the amyloid-β peptide (Aβ), and intracellular aggregates of hyperphosphorylated TAU protein. This review aims to provide an overview of the in vivo studies of the last 5 years in the literature describing the role of the different miRNAs involved in AD. miRNAs hold huge potential as diagnostic and prognostic biomarkers and, at the same time, their modulation could be a potential therapeutic strategy against AD.

MicroRNA-200a-3p Mediates Neuroprotection in Alzheimer-Related Deficits and Attenuates Amyloid-Beta Overproduction and Tau Hyperphosphorylation via Coregulating BACE1 and PRKACB

Alzheimer’s disease (AD) is characterized by two landmark pathologies, the overproduction of amyloid-beta peptides (Aβ), predominated by the β-amyloid protein precursor cleaving enzyme 1 (BACE1), and hyperphosphorylation of the microtubule protein, tau, because of an imbalance in a kinase/phosphatase system that involves the activation of the protein kinase A (PKA). Current evidence indicates that brain microRNAs participate in multiple aspects of AD pathology. Here, the role and underlying molecular mechanisms of microRNA-200a-3p (miR-200a-3p) in mediating neuroprotection against AD-related deficits were investigated. The expression of miR-200a-3p was measured in the hippocampus of APP/PS1 and SAMP8 mice and in an AD cell model in vitro, as well as in blood plasma extracted from AD patients. The targets of miR-200a-3p were determined using bioinformatics and dual-luciferase assay analyses. In addition, cell apoptosis was detected using flow cytometry, and related protein levels were measured using Western blot and enzyme-linked immunosorbent assay (ELISA) techniques. miR-200a-3p was confirmed to be depressed in microarray miRNA profile analysis in vitro and in vivo, suggesting that miR-200a-3p is a potential biomarker of AD. Subsequently, miR-200a-3p was demonstrated to inhibit cell apoptosis accompanied by the inactivation of the Bax/caspase-3 axis and downregulation of Aβ_1-42 and tau phosphorylation levels in vitro. Further mechanistic studies revealed that miR-200a-3p reduced the production of Aβ_1-42 and decreased hyperphosphorylation of tau by regulating the protein translocation of BACE1 and the protein kinase cAMP-activated catalytic subunit beta (PRKACB) associated with the three prime untranslated regions, respectively. Importantly, the function of miR-200a-3p was reversed by overexpression of BACE1 or PRKACB in cultured cells. This resulted in an elevation in cell apoptosis and increases in Aβ_1-42 and tau hyperphosphorylation levels, involving the epitopes threonine 205 and serine 202, 214, 396, and 356, the favorable phosphorylated sites of PKA. In conclusion, our study suggests that miR-200a-3p is implicated in the pathology of AD, exerting neuroprotective effects against Aβ-induced toxicity by two possible mechanisms: one involving the inhibition of Aβ overproduction via suppression of the expression of BACE1 and synergistically decreasing the hyperphosphorylation of tau via attenuation of the expression of PKA.

MicroRNAs in Alzheimer's Disease: Diagnostic Markers or Therapeutic Agents?

MicroRNAs (miRNAs) are small non-coding nucleic acids able to post-transcriptionally regulate gene expression by binding to complementary sequences of target messenger RNA (mRNA). It has been estimated that at least 1% of the human genome encodes miRNA and every miRNA can regulate up to 200 mRNAs. These findings suggest that dysregulation of miRNA expression could be associated with several human pathological conditions including central neurological disorders. Alzheimer’s disease (AD) is a neurodegenerative disorder and the most common cause of dementia in the elderly. The characteristic symptoms are a progressive loss of memory and other cognitive functions due to the impairment of particular types of neurons and synapses, leading to neuronal death. At present, the available symptomatic treatments can only slow down disease progression without stopping it. miRNAs are widely found within the nervous system where they are key regulators of functions such as neurite outgrowth, dendritic spine morphology, neuronal differentiation, and synaptic plasticity. This has been the clue for considering miRNAs crucial molecules to be studied in AD, and nowadays, dysfunction of miRNAs in AD is increasingly recognized. In this review, we summarized existing evidence about miRNAs as biomarkers or therapeutic agents. The field of miRNAs as biomarkers is more advanced in terms of human data, and it is likely that miRNAs will be used successfully in the near future. Given the huge number of miRNAs potentially involved in diagnostics, miRNA panels will be used for specific tasks such as the stage of the disease, the risk prediction, and disease progression. The field of miRNAs as therapeutics is rapidly developing, and it offers a huge variety of solutions. These include positive effects related to beta-amyloid or tau reduction, increased number of neurons, inhibition of apoptosis, protection of synapses, transformation of other cellular elements into missing/deficient neurons in AD, and so on. It is predictable that both areas of research will be carried forward. However, given the absence of an AD therapy able to stop or reverse the disease, it is desirable to accelerate research on miRNAs as therapeutic agents.

Sirtuins in Alzheimer's Disease: SIRT2-Related GenoPhenotypes and Implications for PharmacoEpiGenetics

Sirtuins (SIRT1-7) are NAD⁺-dependent protein deacetylases/ADP ribosyltransferases with important roles in chromatin silencing, cell cycle regulation, cellular differentiation, cellular stress response, metabolism and aging. Sirtuins are components of the epigenetic machinery, which is disturbed in Alzheimer’s disease (AD), contributing to AD pathogenesis. There is an association between the SIRT2-C/T genotype (rs10410544) (50.92%) and AD susceptibility in the APOEε4-negative population (SIRT2-C/C, 34.72%; SIRT2-T/T 14.36%). The integration of SIRT2 and APOE variants in bigenic clusters yields 18 haplotypes. The 5 most frequent bigenic genotypes in AD are 33CT (27.81%), 33CC (21.36%), 34CT (15.29%), 34CC (9.76%) and 33TT (7.18%). There is an accumulation of APOE-3/4 and APOE-4/4 carriers in SIRT2-T/T > SIRT2-C/T > SIRT2-C/C carriers, and also of SIRT2-T/T and SIRT2-C/T carriers in patients who harbor the APOE-4/4 genotype. SIRT2 variants influence biochemical, hematological, metabolic and cardiovascular phenotypes, and modestly affect the pharmacoepigenetic outcome in AD. SIRT2-C/T carriers are the best responders, SIRT2-T/T carriers show an intermediate pattern, and SIRT2-C/C carriers are the worst responders to a multifactorial treatment. In APOE-SIRT2 bigenic clusters, 33CC carriers respond better than 33TT and 34CT carriers, whereas 24CC and 44CC carriers behave as the worst responders. CYP2D6 extensive metabolizers (EM) are the best responders, poor metabolizers (PM) are the worst responders, and ultra-rapid metabolizers (UM) tend to be better responders that intermediate metabolizers (IM). In association with CYP2D6 genophenotypes, SIRT2-C/T-EMs are the best responders. Some Sirtuin modulators might be potential candidates for AD treatment.

Aging, Melatonin, and the Pro- and Anti-Inflammatory Networks

Aging and various age-related diseases are associated with reductions in melatonin secretion, proinflammatory changes in the immune system, a deteriorating circadian system, and reductions in sirtuin-1 (SIRT1) activity. In non-tumor cells, several effects of melatonin are abolished by inhibiting SIRT1, indicating mediation by SIRT1. Melatonin is, in addition to its circadian and antioxidant roles, an immune stimulatory agent. However, it can act as either a pro- or anti-inflammatory regulator in a context-dependent way. Melatonin can stimulate the release of proinflammatory cytokines and other mediators, but also, under different conditions, it can suppress inflammation-promoting processes such as NO release, activation of cyclooxygenase-2, inflammasome NLRP3, gasdermin D, toll-like receptor-4 and mTOR signaling, and cytokine release by SASP (senescence-associated secretory phenotype), and amyloid-β toxicity. It also activates processes in an anti-inflammatory network, in which SIRT1 activation, upregulation of Nrf2 and downregulation of NF-κB, and release of the anti-inflammatory cytokines IL-4 and IL-10 are involved. A perhaps crucial action may be the promotion of macrophage or microglia polarization in favor of the anti-inflammatory phenotype M2. In addition, many factors of the pro- and anti-inflammatory networks are subject to regulation by microRNAs that either target mRNAs of the respective factors or upregulate them by targeting mRNAs of their inhibitor proteins.

Upregulation of miR-200a and miR-204 in MPP+ -treated differentiated PC12 cells as a model of Parkinson's disease

Background

Parkinson's disease (PD) is ranked as the second most common neurodegenerative disorder caused by loss of dopaminergic neurons in the substantia nigra. Micro(mi)RNAs are a class of small noncoding RNAs that regulate gene expression and aberrant expression of them is closely correlated with many neurodegenerative conditions including PD. Silent information regulator 1 (SIRT1) as a known deacetylase and B‐cell lymphoma‐2 (BCL2) as an antiapoptotic factor play vital roles in neural protection and survival.

Methods

Differentiated PC12 cells exposed to MPP⁺ were served here as a known PD model. Cell viability was determined by MTS assay. Apoptotic cells and ROS levels were detected using flow cytometry. Gene selection and miRNA–mRNA interaction analysis were performed through in silico methods. Relative expression of miRNAs and genes was examined by RT‐qPCR.

Results

MPP⁺ exposure markedly reduced cell viability, enhanced oxidative stress, and induced apoptosis in differentiated PC12 cells. Sirt1 and BCL2were shown to be markedly declined in response to MPP⁺, while miR‐200a and miR‐204 were significantly upregulated.

Conclusion

The first novel finding of the current study is altered expression of miR‐200a and miR‐204 in differentiated PC12 cells in response to MPP⁺, suggesting that deregulation of them participate in MPP⁺ neurotoxicity mechanisms, possibly via affecting the expression of Sirt1 and BCL2 as potential targets.

Retracted Article: Berberine alleviates amyloid beta-induced injury in Alzheimer's disease by miR-107/ZNF217

Berberine plays a neuroprotective role in neurodegenerative disorders, including Alzheimer's disease (AD). However, the underlying mechanism by which berberine inhibits AD progression remains largely unclear. The AD model was established using PC12 cells after treatment of amyloid beta (Aβ)_25-35. Cells were transfected with microRNA (miRNA)-107 mimic, inhibitor, zinc finger protein 217 (ZNF217) overexpression or corresponding negative controls. Cell viability, apoptosis and inflammatory cytokine secretion were measured by MTT, flow cytometry or enzyme linked immunosorbent assay, respectively. The expressions of miR-107, ZNF217 and phosphorylated tau (p-Tau) were detected by quantitative real-time polymerase chain reaction or Western blot. The association between miR-107 and ZNF217 was explored by luciferase reporter assay and RNA immunoprecipitation. Berberine attenuated Aβ_25-35-induced viability suppression in PC12 cells. Moreover, berberine inhibited the Aβ_25-35-induced increase of inflammatory cytokine expression, apoptosis and p-Tau level in PC12 cells. miR-107 expression was reduced in Aβ_25-35-treated PC12 cells and its overexpression alleviated Aβ_25-35-induced injury, which was further weakened by combination with berberine. ZNF217 was a target of miR-107 and its addition reversed miR-107-mediated inhibition of inflammatory injury, apoptosis and phosphorylation of tau. Besides, ZNF217 protein level was decreased by berberine via regulating miR-107 in Aβ_25-35-treated PC12 cells. Berberine protected against Aβ_25-35-induced inflammatory injury, apoptosis and phosphorylation of tau by regulating miR-107 and ZNF217, indicating berberine as a promising neuroprotective agent for therapeutics of AD.

Berberine plays a neuroprotective role in neurodegenerative disorders, including Alzheimer's disease (AD).

SIRT1 downregulation mediated Manganese-induced neuronal apoptosis through activation of FOXO3a-Bim/PUMA axis

Manganese (Mn) is an essential trace element. Excessive exposure to Mn may lead to neuronal death and neurodegenerative disorders. Accumulating evidence has shown that silent mating type information regulation 2 homolog 1 (SIRT1) plays a vital role in brain damage. However, whether aberrant SIRT1 levels contribute to Mn-induced neurotoxicity remains unknown. In this study, we report the important role of SIRT1 downregulation during Mn-induced neuronal apoptosis. Mn was found to downregulate SIRT1 protein levels in the rat pheochromocytoma (PC12) cells and mouse brain tissues. Mn enhanced SIRT1 protein degradation and downregulated its gene expression. Furthermore, Mn induced cell apoptosis in a dose-dependent manner both in vitro and in vivo, and resulted in an increase in forkhead box O (FOXO) 3a expression and acetylation. SIRT1 activation by resveratrol clearly attenuated Mn-triggered apoptosis and FOXO3a activation. Mn markedly increased the expression of Bcl-2 interacting mediator of cell death (Bim) and p53-up-regulated modulator of apoptosis (PUMA), whereas downregulation of FOXO3a significantly inhibited their upregulation and subsequent apoptosis. In summary, we determined that Mn downregulated SIRT1 by multiple mechanisms, thus led to apoptosis via activation of the FOXO3a-Bim/PUMA axis in PC12 cells. These findings on the impact of Mn on SIRT1 may lead to an improved understanding of Mn-induced neurotoxicity and provide a molecular target to antagonise Mn-associated neuronal damage.

Non-coding RNA influences in dementia

Dementia is a complex clinical syndrome characterised by progressive decline in cognitive function. It usually presents itself as impairment in memory, loss of judgement, abstract thinking and other disturbances that are severe enough to interfere with activities of daily living. It has long been considered as one of the major challenges at present posing an ever-increasing demand on global health and social care systems. Of all the different forms of dementia, Alzheimer's disease (AD) is the most common. The term non-coding RNA (ncRNA) refers to RNA sequences which do not have the ability to be translated into proteins and therefore mainly fall within the realm of the recently acknowledged ‘dark matter’ of the genome. This genomic dark matter encompasses a whole spectrum of differing ncRNA families such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), PIWI-interacting RNAs (piRNAs), transfer RNAs (tRNAs), small nuclear RNAs (snoRNAs) and circular RNAs (circRNAs), to name but a few. Consequently, due to the widespread influences of miRNAs and lncRNAs across all disease pathways, it is of critical importance for researchers in the field of dementia to focus their attention on possible ncRNA-induced pathogeneses, with the ultimate goal of identifying novel diagnostic procedures and drug targets, together with the development of novel therapies to control such a devastating mental condition in the patient population.

Neuroprotective Effect of Tetrahedral DNA Nanostructures in a Cell Model of Alzheimer's Disease

Accumulating evidence supports the abnormal deposition of amyloid β-peptide (Aβ) as the main cause of Alzheimer's disease (AD). Therefore, fighting against the formation, deposition, and toxicity of Aβ is a basic strategy for the treatment of AD. In the process of in vitro nerve cell culture, screening out drugs that can antagonize a series of toxic reactions caused by β-amyloid deposition has become an effective method for the follow-up treatment of AD. Our previous studies showed that tetrahedral DNA nanostructures (TDNs) had good biocompatibility and had some positive effects on the biological behavior of cells. In this study, the main aim of our work was to explore the effects and potential mechanism of TDNs in protecting neuronal PC12 cells from the toxicity of Aβ. Our study demonstrated that TDNs can protect and rescue PC12 cell death through Aβ25-35-induced PC12 cell apoptosis. Further studies showed that TDNs significantly improved the apoptosis by affecting the abnormal cell cycle, restoring abnormal nuclear morphology and caspase activity. Western blot analysis showed that TDNs could prevent the damage caused by Aβ deposition by activating the ERK1/2 pathway and thus be a potential therapeutic agent with a neuroprotective effect in Alzheimer's disease. Our finding provides a potential application of TDNs in the prevention and treatment of AD.