miR-124 regulates cerebromicrovascular function in APP/PS1 transgenic mice via C1ql3

Mechanisms linking cerebrovascular dysfunction and tauopathy: Adding a layer of epiregulatory complexity

Intracellular accumulation of hyperphosphorylated misfolded tau proteins are found in many neurodegenerative tauopathies, including Alzheimer's disease (AD). Tau pathology can impact cerebrovascular physiology and function through multiple mechanisms. In vitro and in vivo studies have shown that alterations in the blood-brain barrier (BBB) integrity and function can result in synaptic abnormalities and neuronal damage. In the present review, we will summarize how tau proteostasis dysregulation contributes to vascular dysfunction and, conversely, we will examine the factors and pathways leading to tau pathological alterations triggered by cerebrovascular dysfunction. Finally, we will highlight the role epigenetic and epitranscriptomic factors play in regulating the integrity of the cerebrovascular system and the progression of tauopathy including a few observartions on potential therapeutic interventions. LINKED ARTICLES: This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

Microglia-derived extracellular vesicles in homeostasis and demyelination/remyelination processes

Microglia (MG) play a crucial role as the predominant myeloid cells in the central nervous system and are commonly activated in multiple sclerosis. They perform essential functions under normal conditions, such as actively surveying the surrounding parenchyma, facilitating synaptic remodeling, engulfing dead cells and debris, and protecting the brain against infectious pathogens and harmful self-proteins. Extracellular vesicles (EVs) are diverse structures enclosed by a lipid bilayer that originate from intracellular endocytic trafficking or the plasma membrane. They are released by cells into the extracellular space and can be found in various bodily fluids. EVs have recently emerged as a communication mechanism between cells, enabling the transfer of functional proteins, lipids, different RNA species, and even fragments of DNA from donor cells. MG act as both source and recipient of EVs. Consequently, MG-derived EVs are involved in regulating synapse development and maintaining homeostasis. These EVs also directly influence astrocytes, significantly increasing the release of inflammatory cytokines like IL-1β, IL-6, and TNF-α, resulting in a robust inflammatory response. Furthermore, EVs derived from inflammatory MG have been found to inhibit remyelination, whereas Evs produced by pro-regenerative MG effectively promote myelin repair. This review aims to provide an overview of the current understanding of MG-derived Evs, their impact on neighboring cells, and the cellular microenvironment in normal conditions and pathological states, specifically focusing on demyelination and remyelination processes.

Repressor Element-1 Binding Transcription Factor (REST) as a Possible Epigenetic Regulator of Neurodegeneration and MicroRNA-Based Therapeutic Strategies

Neurodegenerative disorders (NDD) have grabbed significant scientific consideration due to their fast increase in prevalence worldwide. The specific pathophysiology of the disease and the amazing changes in the brain that take place as it advances are still the top issues of contemporary research. Transcription factors play a decisive role in integrating various signal transduction pathways to ensure homeostasis. Disruptions in the regulation of transcription can result in various pathologies, including NDD. Numerous microRNAs and epigenetic transcription factors have emerged as candidates for determining the precise etiology of NDD. Consequently, understanding by what means transcription factors are regulated and how the deregulation of transcription factors contributes to neurological dysfunction is important to the therapeutic targeting of pathways that they modulate. RE1-silencing transcription factor (REST) also named neuron-restrictive silencer factor (NRSF) has been studied in the pathophysiology of NDD. REST was realized to be a part of a neuroprotective element with the ability to be tuned and influenced by numerous microRNAs, such as microRNAs 124, 132, and 9 implicated in NDD. This article looks at the role of REST and the influence of various microRNAs in controlling REST function in the progression of Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD) disease. Furthermore, to therapeutically exploit the possibility of targeting various microRNAs, we bring forth an overview of drug-delivery systems to modulate the microRNAs regulating REST in NDD.

Curcumin ameliorates traumatic brain injury via C1ql3-mediated microglia M2 polarization

PURPOSE

Curcumin can regulate the polarization of microglia and alleviate traumatic brain injury (TBI). However, its detailed action mechanism on downregulating Complement 1q-like-3 protein (C1ql3) in TBI is less reported. The purpose of this study is to explore the role and mechanism of curcumin-regulated C1ql3 in TBI.

METHOD

GSE23639 dataset was used to acquire gene data for microglia. C57BL/6 J wild-type (WT) mice were subjected to establish a controlled cortical impact model of TBI. The effects of curcumin (200 mg/kg) on the brain injury, inflammatory cytokine levels, microglia polarization, and C1ql3 protein expression in mice and BV-2 cells were detected by H&E staining, qRT-PCR, immunofluorescence, and Western blot, respectively. The effects of curcumin (5, 10, 20 μmol/L) and lipopolysaccharides (LPS, 1 µg/mL) on the viability of BV-2 cells were determined by MTT assay. After the transfection of C1ql3 overexpression plasmid, C1ql3 expression, IL-1β and IL-6 levels, and the number of CD16+/32+ and CD206+ cells were determined by qRT-PCR, ELISA and flow cytometry, respectively.

RESULT

C1ql3 expression was down-regulated in microglia after the curcumin treatment. Curcumin treatment could alleviate the TBI-induced brain injury in mice, reduce IL-1β and IL-6 levels, promote M2 polarization of microglia, and decrease C1ql3 protein expression. For BV-2 cells, curcumin treatment had no significant toxic effect on cell viability, but reversed the effect of LPS on cells, while C1ql3 overexpression counteracted the effect of curcumin.

CONCLUSION

Curcumin induces M2 microglia polarization through down-regulating C1ql3 expression, which may become a new treatment method for TBI.

AVAILABILITY OF DATA AND MATERIALS

The analyzed data sets generated during the study are available from the corresponding author on reasonable request.

As a Potential Therapeutic Target, C1q Induces Synapse Loss Via Inflammasome-activating Apoptotic and Mitochondria Impairment Mechanisms in Alzheimer's Disease

C1q, the initiator of the classical pathway of the complement system, is activated during Alzheimer's disease (AD) development and progression and is especially associated with the production and deposition of β-amyloid protein (Aβ) and phosphorylated tau in β-amyloid plaques (APs) and neurofibrillary tangles (NFTs). Activation of C1q is responsible for induction of synapse loss, leading to neurodegeneration in AD. Mechanistically, C1q could activate glial cells, which results in the loss of synapses via regulation of synapse pruning and phagocytosis in AD. In addition, C1q induces neuroinflammation by inducing proinflammatory cytokine secretion, which is partially mediated by inflammasome activation. Activation of inflammasomes might mediate the effects of C1q on induction of synapse apoptosis. On the other hand, activation of C1q impairs mitochondria, which hinders the renovation and regeneration of synapses. All these actions of C1q contribute to the loss of synapses during neurodegeneration in AD. Therefore, pharmacological, or genetic interventions targeting C1q may provide potential therapeutic strategies for combating AD.

MicroRNA‑124: an emerging therapeutic target in central nervous system disorders

The central nervous system (CNS) consists of neuron and non-neuron cells including neural stem/precursor cells (NSPCs), neuroblasts, glia cells (mainly astrocyte, oligodendroglia and microglia), which thereby form a precise and complicated network and exert diverse functions through interactions of numerous bioactive ingredients. MicroRNAs (miRNAs), with small size approximately  ~ 21nt and as well-documented post-transcriptional key regulators of gene expression, are a cluster of evolutionarily conserved endogenous non-coding RNAs. More than 2000 different miRNAs has been discovered till now. MicroRNA-124(miR-124), the most brain-rich microRNA, has been validated to possess important functions in the central nervous system, including neural stem cell proliferation and differentiation, cell fate determination, neuron migration, synapse plasticity and cognition, cell apoptosis etc. According to recent studies, herein, we provide a review of this conversant miR-124 to further understand the potential functions and therapeutic and clinical value in brain diseases.

miR-124: A Promising Therapeutic Target for Central Nervous System Injuries and Diseases

Central nervous system injuries and diseases, such as ischemic stroke, spinal cord injury, neurodegenerative diseases, glioblastoma, multiple sclerosis, and the resulting neuroinflammation often lead to death or long-term disability. MicroRNAs are small, non-coding, single-stranded RNAs that regulate posttranscriptional gene expression in both physiological and pathological cellular processes, including central nervous system injuries and disorders. Studies on miR-124, one of the most abundant microRNAs in the central nervous system, have shown that its dysregulation is related to the occurrence and development of pathology within the central nervous system. Herein, we review the molecular regulatory functions, underlying mechanisms, and effective delivery methods of miR-124 in the central nervous system, where it is involved in pathological conditions. The review also provides novel insights into the therapeutic target potential of miR-124 in the treatment of human central nervous system injuries or diseases.

MiR-214-3p Prevents the Development of Perioperative Neurocognitive Disorders in Elderly Rats

OBJECTIVE

This study aimed to identify microRNAs (miRNAs) involved in the development of perioperative neurocognitive disorders (PND).

METHODS

Plasma exosomal miRNA expression was examined in patients before and after cardiopulmonary bypass (CPB) using microarray and qRT-PCR and these patients were diagnosed as PND later. Elderly rats were subjected to CPB, and the cognitive functions were examined. Bioinformatics analysis was conducted to predict the targets of miR-214-3p. Rats were administered rno-miR-214-3p agomir before or after CPB to investigate the role of miR-214-3p in PND development.

RESULTS

We identified 76 differentially expressed plasma exosomal miRNAs in PND patients after surgery (P<0.05, ∣log2FC∣>0.58), including the upregulated hsa-miR-214-3p (P=0.002399392). Prostaglandin-endoperoxide synthase 2 (PTGS2) was predicted as a miR-214-3p target. In rats, CPB reduced the platform crossing numbers and target quadrant stay time, accompanied with hippocampal neuronal necrosis. The rno-miR-214-3p level was significantly increased in plasma exosomes but decreased in rat hippocampus after surgery, exhibiting a negative correlation (P<0.001, r=-0.762). A negative correlation between miR-214-3p and PTGS2 protein expression was also observed in the hippocampus after surgery. Importantly, rno-miR-214-3p agomir treatment, before or after surgery, significantly increased the platform crossing numbers (P=0.035) and target quadrant stay time (P=0.029) compared with negative control. Hippocampal PTGS2 protein level was increased in the untreated surgery group and decreased in response to rno-miR-214-3p agomir treatment before or after surgery (both P<0.05 vs. negative control).

CONCLUSION

These data suggest that miR-214-3p/PTGS2 signaling contributes to the development of PND, serving as a potential therapeutic target for PND.

MicroRNAs in Learning and Memory and Their Impact on Alzheimer’s Disease

Learning and memory formation rely on the precise spatiotemporal regulation of gene expression, such as microRNA (miRNA)-associated silencing, to fine-tune gene expression for the induction and maintenance of synaptic plasticity. Much progress has been made in presenting direct evidence of miRNA regulation in learning and memory. Here, we summarize studies that have manipulated miRNA expression using various approaches in rodents, with changes in cognitive performance. Some of these are involved in well-known mechanisms, such as the CREB-dependent signaling pathway, and some of their roles are in fear- and stress-related disorders, particularly cognitive impairment. We also summarize extensive studies on miRNAs correlated with pathogenic tau and amyloid-β that drive the processes of Alzheimer’s disease (AD). Although altered miRNA profiles in human patients with AD and in mouse models have been well studied, little is known about their clinical applications and therapeutics. Studies on miRNAs as biomarkers still show inconsistencies, and more challenges need to be confronted in standardizing blood-based biomarkers for use in AD.

Non-Coding RNAs as Novel Regulators of Neuroinflammation in Alzheimer's Disease

Alzheimer’s disease (AD) is one of the most common causes of dementia. Although significant breakthroughs have been made in understanding the progression and pathogenesis of AD, it remains a worldwide problem and a significant public health burden. Thus, more efficient diagnostic and therapeutic strategies are urgently required. The latest research studies have revealed that neuroinflammation is crucial in the pathogenesis of AD. Non-coding RNAs (ncRNAs), including long noncoding RNAs (lncRNAs), microRNAs (miRNAs), circular RNAs (circRNAs), PIWI-interacting RNAs (piRNAs), and transfer RNA-derived small RNAs (tsRNAs), have been strongly associated with AD-induced neuroinflammation. Furthermore, several ongoing pre-clinical studies are currently investigating ncRNA as disease biomarkers and therapeutic interventions to provide new perspectives for AD diagnosis and treatment. In this review, the role of different types of ncRNAs in neuroinflammation during AD are summarized in order to improve our understanding of AD etiology and aid in the translation of basic research into clinical practice.

RNA-Seq Profiling of Neutrophil-Derived Microvesicles in Alzheimer's Disease Patients Identifies a miRNA Signature That May Impact Blood-Brain Barrier Integrity

(1) Background: Systemic infection is associated with increased neuroinflammation and accelerated cognitive decline in AD patients. Activated neutrophils produce neutrophil-derived microvesicles (NMV), which are internalised by human brain microvascular endothelial cells and increase their permeability in vitro, suggesting that NMV play a role in blood–brain barrier (BBB) integrity during infection. The current study investigated whether microRNA content of NMV from AD patients is significantly different compared to healthy controls and could impact cerebrovascular integrity. (2) Methods: Neutrophils isolated from peripheral blood samples of five AD and five healthy control donors without systemic infection were stimulated to produce NMV. MicroRNAs isolated from NMV were analysed by RNA-Seq, and online bioinformatic tools were used to identify significantly differentially expressed microRNAs in the NMV. Target and pathway analyses were performed to predict the impact of the candidate microRNAs on vascular integrity. (3) Results: There was no significant difference in either the number of neutrophils (p = 0.309) or the number of NMV (p = 0.3434) isolated from AD donors compared to control. However, 158 microRNAs were significantly dysregulated in AD NMV compared to controls, some of which were associated with BBB dysfunction, including miR-210, miR-20b-5p and miR-126-5p. Pathway analysis revealed numerous significantly affected pathways involved in regulating vascular integrity, including the TGFβ and PDGFB pathways, as well as Hippo, IL-2 and DNA damage signalling. (4) Conclusions: NMV from AD patients contain miRNAs that may alter the integrity of the BBB and represent a novel neutrophil-mediated mechanism for BBB dysfunction in AD and the accelerated cognitive decline seen as a result of a systemic infection.

Dysregulated miRNAs as Biomarkers and Therapeutical Targets in Neurodegenerative Diseases

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

Non-coding RNAs in the regulation of blood–brain barrier functions in central nervous system disorders

The blood–brain barrier (BBB) is an essential component of the neurovascular unit that controls the exchanges of various biological substances between the blood and the brain. BBB damage is a common feature of different central nervous systems (CNS) disorders and plays a vital role in the pathogenesis of the diseases. Non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), long non-coding RNA (lncRNAs), and circular RNAs (circRNAs), are important regulatory RNA molecules that are involved in almost all cellular processes in normal development and various diseases, including CNS diseases. Cumulative evidences have demonstrated ncRNA regulation of BBB functions in different CNS diseases. In this review, we have summarized the miRNAs, lncRNAs, and circRNAs that can be served as diagnostic and prognostic biomarkers for BBB injuries, and demonstrated the involvement and underlying mechanisms of ncRNAs in modulating BBB structure and function in various CNS diseases, including ischemic stroke, hemorrhagic stroke, traumatic brain injury (TBI), spinal cord injury (SCI), multiple sclerosis (MS), Alzheimer's disease (AD), vascular cognitive impairment and dementia (VCID), brain tumors, brain infections, diabetes, sepsis-associated encephalopathy (SAE), and others. We have also discussed the pharmaceutical drugs that can regulate BBB functions via ncRNAs-related signaling cascades in CNS disorders, along with the challenges, perspective, and therapeutic potential of ncRNA regulation of BBB functions in CNS diseases.

Therapeutic Opportunities and Delivery Strategies for Brain Revascularization in Stroke, Neurodegeneration, and Aging

Central nervous system (CNS) diseases, especially acute ischemic events and neurodegenerative disorders, constitute a public health problem with no effective treatments to allow a persistent solution. Failed therapies targeting neuronal recovery have revealed the multifactorial and intricate pathophysiology underlying such CNS disorders as ischemic stroke, Alzheimeŕs disease, amyotrophic lateral sclerosis, vascular Parkisonism, vascular dementia, and aging, in which cerebral microvasculature impairment seems to play a key role. In fact, a reduction in vessel density and cerebral blood flow occurs in these scenarios, contributing to neuronal dysfunction and leading to loss of cognitive function. In this review, we provide an overview of healthy brain microvasculature structure and function in health and the effect of the aforementioned cerebral CNS diseases. We discuss the emerging new therapeutic opportunities, and their delivery approaches, aimed at recovering brain vascularization in this context. SIGNIFICANCE STATEMENT: The lack of effective treatments, mainly focused on neuron recovery, has prompted the search of other therapies to treat cerebral central nervous system diseases. The disruption and degeneration of cerebral microvasculature has been evidenced in neurodegenerative diseases, stroke, and aging, constituting a potential target for restoring vascularization, neuronal functioning, and cognitive capacities by the development of therapeutic pro-angiogenic strategies.

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.

C1q-like 1 is frequently up-regulated in lung adenocarcinoma and contributes to the proliferation and invasion of tumor cells

This study aims to investigate the effects of C1q-like 1 (C1QL1) on the growth and migration of lung adenocarcinoma (LUAD) cells and the underlying mechanism. The expression of C1QL1 in LUAD tissues and its prognostic value were analyzed using the data from The Cancer Genome Atlas (TCGA) database. To investigate the function of C1QL1, loss-of-function and gain-of-function assays were conducted in Calu-3 cells and LTEP-a-2 cells, respectively. Cell growth was evaluated by CCK-8 and colony formation assays. Transwell assays were performed to assess cell invasive and migratory abilities. qRT-PCR and Western blotting were performed to detect RNA and protein expression, respectively. Firstly, we found that C1QL1 was highly expressed and predicted poor outcomes in LUAD patients from TCGA database. Moreover, the mRNA and protein expression levels of C1QL1 were higher in LUAD cells than that in normal lung cells. Results of functional experiments illustrated that depletion of C1QL1 restrained the growth, invasion and migration of Calu-3 cells, meanwhile over-expression of C1QL1 presented the opposite results in LTEP-a-2 cells. Furthermore, we discovered that down-regulation of C1QL1 elevated the protein level of E-cadherin and reduced the protein levels of N-cadherin, Vimentin and Snail in Calu-3 cells, whereas over-expression of C1QL1 led to the opposite outcomes in LTEP-a-2 cells. Our data indicated that C1QL1 functioned as a crucial driver in LUAD cell growth and motility, which might be achieved by modulating epithelial-mesenchymal transition (EMT). These consequences are of important relevance for the design of therapeutic strategies for LUAD.

Aspects of the immune system that impact brain function

The conditions required for effective immune responses to viral or bacterial organisms and chemicals of exogenous origin and to intrinsic molecules of abnormal configuration, are briefly outlined. This is followed by a discussion of endocrine and environmental factors that can lead to excessive continuation of immune activity and persistent elevation of inflammatory responses. Such disproportionate activity becomes increasingly pronounced with aging and some possible reasons for this are considered. The specific vulnerability of the nervous system to prolonged immune events is involved in several disorders frequently found in the aging brain. In addition of being a target for inflammation associated with neurodegenerative disease, the nervous system is also seriously impacted by systemically widespread immune disturbances since there are several means by which immune information can access the CNS. The activation of glial cells and cells of non-nervous origin that form the basis of immune responses within the brain, can occur in differing modes resulting in widely differing consequences. The events underlying the relatively frequent occurrence of derangement and hyperreactivity of the immune system are considered, and a few potential ways of addressing this common condition are described.

MiR-124 and the Underlying Therapeutic Promise of Neurodegenerative Disorders

Neurodegenerative disorders (NDDs) are a group of chronic progressive neurological diseases based on primary neurodegeneration. The common pathological characteristics of various NDDs are neuronal degeneration, deletion, glial cell proliferation, and hypertrophy at specific locations in the nervous system. Proliferation and hypertrophy of microglia are manifestations of inflammation. MicroRNAs (miRNAs) have emerged as pivotal regulators of glial cells. MiRNAs are small non-coding molecules that regulate gene expression. Altered expression of miRNAs has been associated with several NDD pathological processes, among which regulation of the inflammatory response is key and a research hotspot at present. At the same time, miRNAs are also biological markers for diagnosis and potential targets for treating NDDs. MiR-124 is highly conserved and enriched in the mammalian brain. Emerging studies have suggested that miR-124 is closely related to the pathogenesis of NDDs and may be an effective treatment strategy to reduce inflammation associated with NDDs. In this review, we describe a summary of general miRNA biology, implications in pathophysiology, the potential roles of miR-124 associated with inflammation, and the use of miRNA as a future biomarker and an application for NDD therapy.