MicroRNAs and the Genetic Nexus of Brain Aging, Neuroinflammation, Neurodegeneration, and Brain Trauma

Age-dependent increase in apoptosis is associated with dysregulation of miR-92a/Akt/mTOR and NF-κB signaling pathways in male rats

Brain aging is the leading risk factor for most neurodegenerative diseases and has been linked with high rates of neuron loss. Thus, identifying molecular mechanisms underlying neuron loss and pharmacological modulation may be of great importance for slowing or preventing age-related diseases. Herein, we investigated the roles of miR-92a, Akt, mTOR, and NF-κB in age-associated apoptosis in the hippocampus (a critical structure involved in brain aging) of male rats alone and in combination with prazosin. Twenty-four male Wistar rats were grouped into young control (3-month-old), aged (18-month-old), and aged + prazosin groups (n = 8 for each). Prazosin (1 mg/kg; i.p.) was administered for 4 weeks to aged rats. Apoptosis was detected by TUNEL staining. Western blot for Akt, mTOR, and NF-κB was conducted. miR-92a gene expression was performed by using RT-PCR. The results indicated a marked enhancement of apoptosis in the aging hippocampus. We also detected substantial up-regulation of NF-κB as well as substantial down-regulation of phosphorylated-Akt and mTOR in the aging hippocampus. Moreover, miR-92a gene expression was markedly reduced in the aging hippocampus. Treatment with prazosin significantly suppressed apoptosis and reversed miR-92a gene expression, as well as Akt, mTOR, and NF-κB protein expressions in the aging hippocampus. Considering the NF-κB regulatory role on miRNAs, our results suggest that NF-κB may be a negative transcriptional regulator of miR-92a, which in turn could regulate the Akt/mTOR signaling. In this regard, NF-κB upregulation may mediate the downregulation of miR-92a/Akt/mTOR axis, and thereby contribute to age-related neurodegeneration. This may provide a novel treatment target for delaying or preventing age-related problems.

MiRNA Dysregulation in Brain Injury: An In Silico Study to Clarify the Role of a MiRNA Set

BACKGROUND

The identification of specific circulating miRNAs has been proposed as a valuable tool for elucidating the pathophysiology of brain damage or injury and predicting patient outcomes.

OBJECTIVE

This study aims to apply several bioinformatic tools in order to clarify miRNA interactions with potential genes involved in brain injury, emphasizing the need of using a computational approach to determine the most likely correlations between miRNAs and target genes. Specifically, this study centers on elucidating the roles of miR-34b, miR-34c, miR-135a, miR-200c, and miR-451a.

METHODS

After a careful evaluation of different software available (analyzing the strengths and limitations), we applied three tools, one to perform an analysis of the validated targets (miRTarBase), and two to evaluate functional annotations (miRBase and TAM 2.0).

RESULTS

Research findings indicate elevated levels of miR-135a and miR-34b in patients with traumatic brain injury (TBI) within the first day post-injury, while miR-200c and miR-34c were found to be upregulated after 7 days. Moreover, miR-451a and miR-135a were found overexpressed in the serum, while miRNAs 34b, 34c, and 200c, had lower serum levels at baseline post brain injury.

CONCLUSION

This study emphasizes the use of computational methods in determining the most likely relationships between miRNAs and target genes by investigating several bioinformatic techniques to elucidate miRNA interactions with potential genes. Specifically, this study focuses on the functions of miR-34b, miR-34c, miR-135a, miR-200c, and miR-451a, providing an up-to-date overview and suggesting future research directions for identifying theranomiRNAs related to brain injury, both at the tissue and serum levels.

The epigenetics of frailty

The conceptual change of frailty, from a physical to a biopsychosocial phenotype, expanded the field of frailty, including social and behavioral domains with critical interaction between different frailty models. Environmental exposures - including physical exercise, psychosocial factors and diet - may play a role in the frailty pathophysiology. Complex underlying mechanisms involve the progressive interactions of genetics with epigenetics and of multimorbidity with environmental factors. Here we review the literature on possible mechanisms explaining the association between epigenetic hallmarks (i.e., global DNA methylation, DNA methylation age acceleration and microRNAs) and frailty, considered as biomarkers of aging. Frailty could be considered the result of environmental epigenetic factors on biological aging, caused by conflicting DNA methylation age and chronological age.

Post-traumatic Stress Disorder: Focus on Neuroinflammation

Post-traumatic stress disorder (PTSD), gaining increasing attention, is a multifaceted psychiatric disorder that occurs following a stressful or traumatic event or series of events. Recently, several studies showed a close relationship between PTSD and neuroinflammation. Neuroinflammation, a defense response of the nervous system, is associated with the activation of neuroimmune cells such as microglia and astrocytes and with changes in inflammatory markers. In this review, we first analyzed the relationship between neuroinflammation and PTSD: the effect of stress-derived activation of the hypothalamic-pituitary-adrenal (HPA) axis on the main immune cells in the brain and the effect of stimulated immune cells in the brain on the HPA axis. We then summarize the alteration of inflammatory markers in brain regions related to PTSD. Astrocytes are neural parenchymal cells that protect neurons by regulating the ionic microenvironment around neurons. Microglia are macrophages of the brain that coordinate the immunological response. Recent studies on these two cell types provided new insight into neuroinflammation in PTSD. These contribute to promoting comprehension of neuroinflammation, which plays a pivotal role in the pathogenesis of PTSD.

Daphne genkwa flower extract promotes the neuroprotective effects of microglia

BACKGROUND

Microglia are innate immune cells in the central nervous system that play a crucial role in neuroprotection by releasing neurotrophic factors, removing pathogens through phagocytosis, and regulating brain homeostasis. The constituents extracted from the roots and stems of the Daphne genkwa plant have shown neuroprotective effects in an animal model of Parkinson's disease. However, the effect of Daphne genkwa plant extract on microglia has yet to be demonstrated.

PURPOSE

To study the anti-inflammatory and neuroprotective effects of Daphne genkwa flower extract (GFE) in microglia and explore the underlying mechanisms.

METHODS

In-vitro mRNA expression levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase, Arginase1, and brain derived neurotropic factor (BDNF) were analyzed by reverse transcription polymerase chain reaction in microglia cells. Nitric oxide (NO) and TNF-α protein were respectively analyzed by Griess reagent and Enzyme Linked Immunosorbent Assay. Immunoreactivity of Iba-1, Neu-N, and BDNF in mouse brain were analyzed by immunofluorescence staining. Phagocytosis capacity of microglia was examined using fluorescent zymosan-red particles.

RESULTS

GFE significantly inhibited lipopolysaccharide (LPS)-induced neuroinflammation and promoted neuroprotection both in vitro and in vivo. First, GFE inhibited the LPS-induced inflammatory factors NO, iNOS, and TNF-α in microglial cell lines and primary glial cells, thus demonstrating anti-inflammatory effects. Arginase1 and BDNF mRNA levels were increased in primary glial cells treated with GFE. Phagocytosis was also increased in microglia treated with GFE, suggesting a neuroprotective effect of GFE. In vivo, neuroprotective and anti-neuroinflammatory effects of GFE were also found in the mouse brain, as oral administration of GFE significantly inhibited LPS-induced neuronal loss and inflammatory activation of microglia.

CONCLUSION

GFE has anti-inflammatory effects and promotes microglial neuroprotective effects. GFE inhibited the pro-inflammatory mediators and enhanced neuroprotective microglia activity by increasing BDNF expression and phagocytosis. These novel findings of the GFE effect on microglia show an innovative approach that can potentially promote neuroprotection for the prevention of neurodegenerative diseases.

miRNome Profiling Detects miR-101-3p and miR-142-5p as Putative Blood Biomarkers of Frailty Syndrome

Frailty is an aging-related pathology, defined as a state of increased vulnerability to stressors, leading to a limited capacity to meet homeostatic demands. Extracellular microRNAs (miRNAs) were proposed as potential biomarkers of various disease conditions, including age-related pathologies. The primary objective of this study was to identify blood miRNAs that could serve as potential biomarkers and candidate mechanisms of frailty. Using the Fried index, we enrolled 22 robust and 19 frail subjects. Blood and urine samples were analysed for several biochemical parameters. We observed that sTNF-R was robustly upregulated in the frail group, indicating the presence of an inflammatory state. Further, by RNA-seq, we profiled 2654 mature miRNAs in the whole blood of the two groups. Expression levels of selected differentially expressed miRNAs were validated by qPCR, and target prediction analyses were performed for the dysregulated miRNAs. We identified 2 miRNAs able to significantly differentiate frail patients from robust subjects. Both miR-101-3p and miR-142-5p were found to be downregulated in the frail vs. robust group. Finally, using bioinformatics targets prediction tools, we explored the potential molecular mechanisms and cellular pathways regulated by the two miRNAs and potentially involved in frailty.

Kynurenine Pathway Metabolites as Biomarkers in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that deteriorates cognitive function. Patients with AD generally exhibit neuroinflammation, elevated beta-amyloid (Aβ), tau phosphorylation (p-tau), and other pathological changes in the brain. The kynurenine pathway (KP) and several of its metabolites, especially quinolinic acid (QA), are considered to be involved in the neuropathogenesis of AD. The important metabolites and key enzymes show significant importance in neuroinflammation and AD. Meanwhile, the discovery of changed levels of KP metabolites in patients with AD suggests that KP metabolites may have a prominent role in the pathogenesis of AD. Further, some KP metabolites exhibit other effects on the brain, such as oxidative stress regulation and neurotoxicity. Both analogs of the neuroprotective and antineuroinflammation metabolites and small molecule enzyme inhibitors preventing the formation of neurotoxic and neuroinflammation compounds may have potential therapeutic significance. This review focused on the KP metabolites through the relationship of neuroinflammation in AD, significant KP metabolites, and associated molecular mechanisms as well as the utility of these metabolites as biomarkers and therapeutic targets for AD. The objective is to provide references to find biomarkers and therapeutic targets for patients with AD.

Forkhead Box 1(FoxO1) mediates psychological stress-induced neuroinflammation

OBJECTIVES

 Neuroinflammation plays a key role in cerebrovascular disease (CVD). Neuropsychiatric disorders appear to share an epidemiological association with inflammation, but the mechanisms are unclear. Forkhead box 1 (FoxO1) regulates inflammatory signaling in diabetes and cardiovascular diseases, but its role in psychological stress-induced neuroinflammation remains unknown. Therefore, we investigated the potential involvement of FoxO1 in repeated social defeat stress (RSDS)-induced neuroinflammation.

METHODS

 6-week-old male C57BL/6 J mice were randomly divided into RSDS or control groups. In the RSDS group, mice (18-22 g) were individually subjected to social defeat by an 8-week-old CD-1 mouse (28-32 g) for 10 min daily for 10 consecutive days. At 24 h after this 10-day process, corticosterone (CORT), epinephrine (EPI), hydrogen peroxide, and inflammatory factors (TNF-α, IL-6, IL-1β, and VCAM-1) from serum and brain tissues were assayed using ELISA, real-time PCR, and Western blot. Iba-1 was determined by immunofluorescence (IF), and FoxO1 siRNA was transfected into BV2 cells to further analyze the expression of inflammatory factors.

RESULTS

RSDS significantly increased the levels of TNF-α, IL-6, IL-1β, and VCAM-1 in the serum; it also increased both mRNA and protein expression of these in the brain. FoxO1 was significantly increased after stress, while its knockdown significantly suppressed stress-induced inflammation. Immunofluorescence demonstrated the activation of microglia in the setting of RSDS.

CONCLUSION

RSDS induced a measurable inflammatory response in the blood and brain, and FoxO1 was demonstrated in vitro to aggravate stress-induced inflammation.

The Potential Role of miRNAs in Cognitive Frailty

Frailty is an aging related condition, which has been defined as a state of enhanced vulnerability to stressors, leading to a limited capacity to meet homeostatic demands. Cognitive impairment is also frequent in older people, often accompanying frailty. Age is the main independent risk factor for both frailty and cognitive impairment, and compelling evidence suggests that similar age-associated mechanisms could underlie both clinical conditions. Accordingly, it has been suggested that frailty and cognitive impairment share common pathways, and some authors proposed "cognitive frailty" as a single complex phenotype. Nevertheless, so far, no clear common underlying pathways have been discovered for both conditions. microRNAs (miRNAs) have emerged as key fine-tuning regulators in most physiological processes, as well as pathological conditions. Importantly, miRNAs have been proposed as both peripheral biomarkers and potential molecular factors involved in physiological and pathological aging. In this review, we discuss the evidence linking changes of selected miRNAs expression with frailty and cognitive impairment. Overall, miR-92a-5p and miR-532-5p, as well as other miRNAs implicated in pathological aging, should be investigated as potential biomarkers (and putative molecular effectors) of cognitive frailty.

A Novel Long-Noncoding RNA LncZFAS1 Prevents MPP+-Induced Neuroinflammation Through MIB1 Activation

Parkinson's disease remains one of the leading neurodegenerative diseases in developed countries. Despite well-defined symptomology and pathology, the complexity of Parkinson's disease prevents a full understanding of its etiological mechanism. Mechanistically, α-synuclein misfolding and aggregation appear to be central for disease progression, but mitochondrial dysfunction, dysfunctional protein clearance and ubiquitin/proteasome systems, and neuroinflammation have also been associated with Parkinson's disease. Particularly, neuroinflammation, which was initially thought to be a side effect of Parkinson's disease pathogenesis, has now been recognized as driver of Parkinson's disease exacerbation. Next-generation sequencing has been used to identify a plethora of long noncoding RNAs (lncRNA) with important transcriptional regulatory functions. Moreover, a myriad of lncRNAs are known to be regulators of inflammatory signaling and neurodegenerative diseases, including IL-1β secretion and Parkinson's disease. Here, LncZFAS1 was identified as a regulator of inflammasome activation, and pyroptosis in human neuroblast SH-SY5Y cells following MPP⁺ treatment, a common in vitro Parkinson's disease cell model. Mechanistically, TXNIP ubiquitination through MIB1 E3 ubiquitin ligase regulates NLRP3 inflammasome activation in neuroblasts. In contrast, MPP⁺ activates the NLPR3 inflammasome through miR590-3p upregulation and direct interference with MIB1-dependent TXNIP ubiquitination. LncZFAS overexpression inhibits this entire pathway through direct interference with miR590-3p, exposing a novel research idea regarding the mechanism of Parkinson's disease.

The emerging role of noncoding RNAs in neuroinflammation: Implications in pathogenesis and therapeutic approaches

Noncoding RNAs (ncRNAs) are important regulators of gene expression in different cell processes. Due to their ability in monitoring neural development genes, these transcripts confer neurons with the potential to exert broad control over the expression of genes for performing neurobiological functions. Although the change of ncRNA expression in different neurodegenerative diseases has been reviewed elsewhere, only recent evidence drove our attention to unravel the involvement of these molecules in neuroinflammation within these devastating disorders. Remarkably, the interactions between ncRNAs and inflammatory pathways are not fully recognized. Therefore, this review has focused on the interplay between diverse inflammatory pathways and the related ncRNAs, including microRNAs, long noncoding RNAs, and competing endogenous RNAs in Alzheimer's disease, Parkinson's diseases, amyotrophic lateral sclerosis, epilepsy, multiple sclerosis, Huntington's disease, and prion diseases. Providing novel insights in the field of combining biomarkers is a critical step for using them as diagnostic tools and therapeutic targets in clinical settings.

The Pathogenesis and Treatment of Cardiovascular Autonomic Dysfunction in Parkinson's Disease: What We Know and Where to Go

Cardiovascular autonomic dysfunctions (CAD) are prevalent in Parkinson’s disease (PD). It contributes to the development of cognitive dysfunction, falls and even mortality. Significant progress has been achieved in the last decade. However, the underlying mechanisms and effective treatments for CAD have not been established yet. This review aims to help clinicians to better understand the pathogenesis and therapeutic strategies. The literatures about CAD in patients with PD were reviewed. References for this review were identified by searches of PubMed between 1972 and March 2021, with the search term “cardiovascular autonomic dysfunctions, postural hypotension, orthostatic hypotension (OH), supine hypertension (SH), postprandial hypotension, and nondipping”. The pathogenesis, including the neurogenic and non-neurogenic mechanisms, and the current pharmaceutical and non-pharmaceutical treatment for CAD, were analyzed. CAD mainly includes four aspects, which are OH, SH, postprandial hypotension and nondipping, among them, OH is the main component. Both non-neurogenic and neurogenic mechanisms are involved in CAD. Failure of the baroreflex circulate, which includes the lesions at the afferent, efferent or central components, is an important pathogenesis of CAD. Both non-pharmacological and pharmacological treatment alleviate CAD-related symptoms by acting on the baroreflex reflex circulate. However, pharmacological strategy has the limitation of failing to enhance baroreflex sensitivity and life quality. Novel OH treatment drugs, such as pyridostigmine and atomoxetine, can effectively improve OH-related symptoms via enhancing residual sympathetic tone, without adverse reactions of supine hypertension. Baroreflex impairment is a crucial pathological mechanism associated with CAD in PD. Currently, non-pharmacological strategy was the preferred option for its advantage of enhancing baroreflex sensitivity. Pharmacological treatment is a second-line option. Therefore, to find drugs that can enhance baroreflex sensitivity, especially via acting on its central components, is urgently needed in the scientific research and clinical practice.

Plasma microRNAs are associated with domain-specific cognitive function in people with HIV

OBJECTIVE

Cognitive impairment remains common in people with HIV (PWH) on antiretroviral therapy (ART). The clinical presentation and severity are highly variable in PWH suggesting that the pathophysiological mechanisms of cognitive complications are likely complex and multifactorial. MicroRNA (miRNA) expression changes may be linked to cognition as they are gene regulators involved in immune and stress responses as well as the development, plasticity, and differentiation of neurons. We examined plasma miRNA expression changes in relation to domain-specific and global cognitive function in PWH.

DESIGN

Cross-sectional observational study.

METHODS

Thirty-three PWH receiving care at the Southern Alberta Clinic, Canada completed neuropsychological (NP) testing and blood draw. Plasma miRNA extraction was followed by array hybridization. Random forest analysis was used to identify the top 10 miRNAs upregulated and downregulated in relation to cognition.

RESULTS

Few miRNAs were identified across cognitive domains; however, when evident a miRNA was only associated with two or three domains. Notably, miR-127-3p was related to learning/memory and miR-485-5p to motor function, miRNAs previously identified in CSF or plasma in Alzheimer's and Parkinson's, respectively. Using miRNET 2.0, a software-platform for understanding the biological relevance of the miRNA-targets (genes) relating to cognition through a network-based approach, we identified genes involved in signaling, cell cycle, and transcription relating to executive function, learning/memory, and language.

CONCLUSION

Findings support the idea that evaluating miRNA expression (or any molecular measure) in the context of global NP function might exclude miRNAs that could be important contributors to the domain-specific mechanisms leading to the variable neuropsychiatric outcomes seen in PWH.

MicroRNA-410 serves as a candidate biomarker in hypoxic-ischemic encephalopathy newborns and provides neuroprotection in oxygen-glucose deprivation-injured PC12 and SH-SY5Y cells

BACKGROUND

MicroRNA-410 (miR-410) has been found to be deregulated in neonatal hypoxic-ischemic encephalopathy (HIE). However, the clinical significance and biological function of miR-410 remain largely elusive. This study aims to investigate the expression and diagnostic performance of miR-410 in HIE newborns, and explores the neuroprotective effect of miR-410 in an oxygen-glucose deprivation (OGD)-induced cell injury model.

METHODS

Expression of miR-410 was examined using quantitative real-time PCR, and its diagnostic performance was evaluated using a receiver operating characteristic analysis. We used OGD-injured PC12 and SH-SY5Y cells to construct an in vitro HIE model. The effect of miR-410 on OGD-induced cell injury was analyzed by assessing cell viability and apoptosis. Enzyme-linked immunosorbent assay was used to evaluate inflammation in cell model. A target gene was assessed according to the luciferase reporter assay.

RESULTS

Serum miR-410 expression was significantly decreased in HIE newborns and OGD-injured cell model. The reduced miR-410 expression served as a biomarker for the diagnosis and progression of HIE. The OGD-induced impaired cell viability, enhanced cell apoptosis, and activated neuroinflammation were abrogated by the overexpression of miR-140 in both PC12 and SH-SY5S cells. Regarding the mechanisms underlying the function of miR-410, phosphatase and tensin homolog (PTEN) was proposed as a direct target of miR-410.

CONCLUSION

All data revealed that serum downregulated miR-410 in HIE serves as candidate diagnostic biomarker, and that miR-410 exerts a neuroprotective role in OGD-injured cells by improving cell viability and inhibiting cell apoptosis through targeting PTEN.

BK Channel-Mediated Microglial Phagocytosis Alleviates Neurological Deficit After Ischemic Stroke

Microglial phagocytosis benefits neurological recovery after stroke. Large-conductance Ca2⁺-activated K⁺ currents are expressed in activated microglia, and BK channel knockout aggravates cerebral ischemic injury. However, the effect of BK channels on microglial phagocytosis after ischemic stroke remains unknown. Here, we explored whether BK channel activation is beneficial for neurological outcomes through microglial phagocytosis after ischemic stroke. ICR mice after transient middle cerebral artery occlusion (tMCAO) were treated with dimethyl sulfoxide (DMSO), BK channel activator NS19504, and inhibitor Paxilline. The results showed a decrease in BK channel expression after tMCAO. BK channel activator NS19504 alleviates neurological deficit after experimental modeling of tMCAO in mice compared to the control. Furthermore, we treated primary microglia with DMSO, NS19504, and Paxilline after oxygen glucose deprivation (OGD). NS19504 promoted primary microglial phagocytosing fluorescent beads and neuronal debris, which reduced neuronal apoptosis after stroke. These effects could be reversed by BK channel inhibitor Paxilline. Finally, NS19504 increased relative phosphorylated extracellular signal-regulated kinase 1/2 expression compared to the Paxilline group at the third day after stroke. Our findings indicate that microglial BK channels are a potential target for acute stage of ischemic stroke therapy.

Integrative Analysis of lncRNA and mRNA and Profiles in Postoperative Delirium Patients

Delirium is a common serious complication that often occurs after major surgery. The goals of this study were to explore the expression profiles and functional networks of long non-coding RNAs (lncRNAs) and mRNAs in patients of postoperative delirium (POD). Microarray analysis was performed on the peripheral blood samples to identify differentially expressed (DE) lncRNAs and mRNAs in 4 POD patients and 4 non-POD volunteers. DE lncRNAs and mRNAs were validated by quantitative reverse transcription PCR (RT-qPCR). Bioinformatic analyses were performed to identify the critical biological functions and signaling pathways involved in POD. A total of 1195 DE lncRNAs and 735 DE mRNAs were identified between the POD and non-POD groups. Verified by the RT-qPCR, we identified 14 DE lncRNAs that may relate to the pathogenesis of POD. These 14 DE lncRNAs play important regulatory roles in “glutamate and 5-hydroxytryptamine,” “synaptotagmin 7,” “transient receptor potential channel,” “interleukin-2 production.” There was a regulatory relationship between lncRNA ENST00000530057 and synaptotagmin (Syt) 7 mRNA. The mRNA level of PCLO was up-regulated in POD group. This study showed abundant DE lncRNAs and mRNAs in POD that might help in deciphering the disease pathogenesis.

Long-term chronic caloric restriction alters miRNA profiles in the brain of ageing mice

Calorie restriction (CR) has been shown to be one of the most effective methods in alleviating the effects of ageing and age-related diseases. Although the protective effects of CR have been reported, the exact molecular mechanism still needs to be clarified. This study aims to determine differentially expressed (DE) miRNAs and altered gene pathways due to long-term chronic (CCR) and intermittent (ICR) CR in the brain of mice to understand the preventive roles of miRNAs resulting from long-term CR. Ten weeks old mice were enrolled into three different dietary groups; ad libitum, CCR or ICR, and fed until 82 weeks of age. miRNAs were analysed using GeneChip 4.1 microarray and the target of DE miRNAs was determined using miRNA target databases. Out of a total 3,163 analysed miRNAs, 55 of them were differentially expressed either by different CR protocols or by ageing. Brain samples from the CCR group had increased expression levels of mmu-miR-713 while decreasing expression levels of mmu-miR-184-3p and mmu-miR-351-5p compared to the other dietary groups. Also, current results indicated that CCR showed better preventive effects than that of ICR. Thus, CCR may perform its protective effects by modulating these specific miRNAs since they are shown to play roles in neurogenesis, chromatin and histone regulation. In conclusion, these three miRNAs could be potential targets for neurodegenerative and ageing-related diseases and may play important roles in the protective effects of CR in the brain.

Age-Dependent Sensitivity to the Neurotoxic Environmental Metabolite, 1,2-Diacetylbenzene

1,2-Diacetylbenzene (DAB) is a metabolite of 1,2-diethylbenzene, which is commonly used in the manufacture of plastics and gasoline. We examined the neurotoxic effects of DAB in young and old rats, particularly its effects on hippocampus. Previously, we reported DAB impairs hippocampal neurogenesis but that the underlying mechanism remained unclear. In this study, we evaluate the toxicities exhibited by DAB in the hippocampi of 6-month-old (young) and 20-month-old (old) male SD rats by treating animals intraperitoneally with DAB at 3 mg/kg/day for 1 week. Hippocampal areas were dissected from brains and RNA was extracted and subjected to RNA-seq analysis. RNA results showed animals exhibited age-dependent sensitivity to the neurotoxic effects of DAB. We observed that inflammatory pathways were up-regulated in old rats but that metabolism- and detoxification-related pathways were up-regulated in young rats. This result in old rats, especially upregulation of the TREM1 signaling pathway (an inflammatory response involved in Alzheimer’s disease (AD)) was confirmed by RT-PCR. Our study results provide a better understanding of age-dependent responses to DAB and new insight into the association between DAB and AD.

Exploring the secrets of brain transcriptional regulation: developing methodologies, recent significant findings, and perspectives

Exploring and revealing the secret of the function of the human brain has been the dream of mankind and science. Delineating brain transcriptional regulation has been extremely challenging, but recent technological advances have facilitated a deeper investigation of molecular processes in the brain. Tracing the molecular regulatory mechanisms of different gene expression profiles in the brain is divergent and has made it possible to connect spatial and temporal variations in gene expression to distributed properties of brain structure and function. Here, we review the molecular diversity of the brain among rodents, non-human primates and humans. We also discuss the molecular mechanism of non-coding DNA/RNA at the transcriptional/post-transcriptional level based on recent technical advances to highlight an improved understanding of the complex transcriptional network in the brain. Spatiotemporal and single-cell transcriptomics have attempted to gain novel insight into the development and evolution of the brain as well as the progression of human diseases. Although it is clear that the field is developing and challenges remain to be resolved, the impressive recent progress provides a solid foundation to better understand the brain and evidence-based recommendations for the diagnosis and treatment of brain diseases.

MicroRNA-298 reduces levels of human amyloid-β precursor protein (APP), β-site APP-converting enzyme 1 (BACE1) and specific tau protein moieties

Alzheimer's disease (AD) is the most common age-related form of dementia, associated with deposition of intracellular neuronal tangles consisting primarily of hyperphosphorylated microtubule-associated protein tau (p-tau) and extracellular plaques primarily comprising amyloid- β (Aβ) peptide. The p-tau tangle unit is a posttranslational modification of normal tau protein. Aβ is a neurotoxic peptide excised from the amyloid-β precursor protein (APP) by β-site APP-cleaving enzyme 1 (BACE1) and the γ-secretase complex. MicroRNAs (miRNAs) are short, single-stranded RNAs that modulate protein expression as part of the RNA-induced silencing complex (RISC). We identified miR-298 as a repressor of APP, BACE1, and the two primary forms of Aβ (Aβ40 and Aβ42) in a primary human cell culture model. Further, we discovered a novel effect of miR-298 on posttranslational levels of two specific tau moieties. Notably, miR-298 significantly reduced levels of ~55 and 50 kDa forms of the tau protein without significant alterations of total tau or other forms. In vivo overexpression of human miR-298 resulted in nonsignificant reduction of APP, BACE1, and tau in mice. Moreover, we identified two miR-298 SNPs associated with higher cerebrospinal fluid (CSF) p-tau and lower CSF Aβ42 levels in a cohort of human AD patients. Finally, levels of miR-298 varied in postmortem human temporal lobe between AD patients and age-matched non-AD controls. Our results suggest that miR-298 may be a suitable target for AD therapy.

The Effect of Melatonin Modulation of Non-coding RNAs on Central Nervous System Disorders: An Updated Review

Melatonin is a hormone produced in and secreted by the pineal gland. Besides its role in regulating circadian rhythms, melatonin has a wide range of protective functions in the central nervous system (CNS) disorders. The mechanisms underlying this protective function are associated with the regulatory effects of melatonin on related genes and proteins. In addition to messenger ribonucleic acid (RNA) that can be translated into protein, an increasing number of non-coding RNAs in the human body are proven to participate in many diseases. This review discusses the current progress of research on the effects of melatonin modulation of non-coding RNAs (ncRNAs), including microRNA, long ncRNA, and circular RNA. The role of melatonin in regulating common pathological mechanisms through these ncRNAs is also summarized. Furthermore, the ncRNAs, currently shown to be involved in melatonin signaling in CNS diseases, are discussed. The information compiled in this review will open new avenues for future research into melatonin mechanisms and provide a further understanding of ncRNAs in the CNS.

Decreased miR-132 plays a crucial role in diabetic encephalopathy by regulating the GSK-3β/Tau pathway

Diabetic encephalopathy (DE) is a global concern and Gordian knot worldwide. miRNA-132 (miR-132) is a class of negative gene regulators that promote diabetic pathologic mechanisms and its complications. However, the molecular mechanisms of miR-132 in DE are elusive, thus an alternative therapeutic strategy is urgently in demand. The present study explored the protective effect and the underlying mechanism of miR-132 on DE via the GSK-β/Tau signaling pathway. Experimentally, a type 2 DM rat model was developed by incorporating a high-fat diet and streptozotocin injection. Further, the DE model was screened via the Morris Water Maze test. Primary hippocampal neurons and HT-22 cells were used for in vitro analysis. We found that hyperglycemia exacerbates cognitive impairment in T2DM rats. When we isolated the primary hippocampus neurons, the expression of miR-132 RNA was low in both the DE hippocampus and primary neurons. GSK-3β and Tau 404 were highly expressed in injured HT-22 cells and diabetic hippocampal tissues. miR-132 downregulated the expression of GSK-3β. Besides, a binding and colocalized relationship between GSK3β and Tau was also reported. These findings suggest that miR-132 exerts protective effects from DE injury by repressing GSK-3β expression and alleviating Tau hyperphosphorylation in HT-22 cells and hippocampus tissues.

Serum microRNA as indicators of Wolfram syndrome's progression in neuroimaging studies

INTRODUCTION

Patients with the ultra-rare Wolfram syndrome (WFS) develop insulin-dependent diabetes and progressive neurodegeneration. The aim of the study was to quantify microRNAs (miRNAs) in sera from patients with WFS, correlate their expression with neurological imaging over time and compare miRNA levels with those observed in patients with type 1 diabetes mellitus (T1DM).

RESEARCH DESIGN AND METHODS

We quantified miRNA expression (Qiagen, Germany) in two groups of patients: with WFS at study entry (n=14) and after 2 years of follow-up and in 15 glycated hemoglobin-matched (p=0.72) patients with T1DM.

RESULTS

We observed dynamic changes in the expression of multiple miRNAs in patients with WFS parallel to disease progression and in comparison to the T1DM patients group. Among miRNAs that differed between baseline and follow-up WFS samples, the level of 5 increased over time (miR-375, miR-30d-5p, miR-30e-30, miR-145-5p and miR-193a-5p) and was inversely correlated with macular average thickness, while the expression of 2 (let-7g-5p and miR-22-3p) decreased and was directly correlated with neuroimaging indicators of neurodegeneration.

CONCLUSIONS

Our findings show for the first time that serum miRNAs can be used as easily accessible indicators of disease progression in patients with WFS, potentially facilitating clinical trials on mitigating neurodegeneration.

Mesenchymal stem cell-derived extracellular vesicle-based therapies protect against coupled degeneration of the central nervous and vascular systems in stroke

Stem cell-based treatments have been suggested as promising candidates for stroke. Recently, mesenchymal stem cells (MSCs) have been reported as potential therapeutics for a wide range of diseases. In particular, clinical trial studies have suggested MSCs for stroke therapy. The focus of MSC treatments has been directed towards cell replacement. However, recent research has lately highlighted their paracrine actions. The secretion of extracellular vesicles (EVs) is offered to be the main therapeutic mechanism of MSC therapy. However, EV-based treatments may provide a wider therapeutic window compared to tissue plasminogen activator (tPA), the traditional treatment for stroke. Exosomes are nano-sized EVs secreted by most cell types, and can be isolated from conditioned cell media or body fluids such as plasma, urine, and cerebrospinal fluid (CSF). Exosomes apply their effects through targeting their cargos such as microRNAs (miRs), DNAs, messenger RNAs, and proteins at the host cells, which leads to a shift in the behavior of the recipient cells. It has been indicated that exosomes, in particular their functional cargoes, play a significant role in the coupled pathogenesis and recovery of stroke through affecting the neurovascular unit (NVU). Therefore, it seems that exosomes could be utilized as diagnostic and therapeutic tools in stroke treatment. The miRs are small endogenous non-coding RNA molecules which serve as the main functional cargo of exosomes, and apply their effects as epigenetic regulators. These versatile non-coding RNA molecules are involved in various stages of stroke and affect stroke-related factors. Moreover, the involvement of aging-induced changes to specific miRs profile in stroke further highlights the role of miRs. Thus, miRs could be utilized as diagnostic, prognostic, and therapeutic tools in stroke. In this review, we discuss the roles of stem cells, exosomes, and their application in stroke therapy. We also highlight the usage of miRs as a therapeutic choice in stroke therapy.

miRNA degradation in the mammalian brain

MicroRNAs (miRNAs) are short, noncoding RNAs that are evolutionarily conserved across many different species. miRNA regulation of gene expression, specifically in the context of the mammalian brain, has been well characterized; however, the regulation of miRNA degradation is still a focus of ongoing research. This review focuses on recent findings concerning the cellular mechanisms that govern miRNA degradation, with an emphasis on target-mediated miRNA degradation and how this phenomenon is uniquely poised to maintain homeostasis in neuronal systems.

Anabolic-androgenic steroids and brain injury: miRNA evaluation in users compared to cocaine abusers and elderly people

Anabolic-androgenic steroids (AASs) can be used to treat both hormonal diseases and other pathologies characterized by muscle loss (aging, cancer, and AIDS). Even if the adverse effects related to the misuse of AASs have been well studied in different systems and apparatuses, knowledge about brain damage is poor.In this scenario, this experimental study aimed to analyze the role of several microRNAs (miRNAs) in brain damage after AAS misuse, to better comprehend the underlying mechanisms. The research hypothesis at the base of this experimental study is that the chronic use of AASs may be associated to brain damage with a dysregulation of these miRNAs. Moreover, miRNA expression values were compared among three different groups, "AAS" group, "Cocaine" group and "Aging" group, in order to define if AAS brain damage can be compared with the brain impairment linked to aging and/or cocaine assumption.This experimental study revealed that the tested miRNAs (hsa-miR-21-5p, hsa-miR-34a-5p, hsa-miR-124-5p, hsa-miR-132-3p, and hsa-miR-144-3p) were overexpressed in all enrolled groups. In the light of the presented results, the identification of specific circulating and/or tissue biomarkers is challenging for the scientific community. Further studies with larger samples are needed to confirm these interesting findings.

MicroRNA-138 promotes neuroblastoma SH-SY5Y cell apoptosis by directly targeting DEK in Alzheimer's disease cell model

BACKGROUND

Alzheimer's disease (AD) is a progressive neuro-degenerative disease with a major manifestation of dementia. MicroRNAs were reported to regulate the transcript expression in patients with Alzheimer's disease (AD). In this study, we investigated the roles of miR-138, a brain-enriched miRNA, in the AD cell model.

METHODS

The targets of miRNA-138 was predicted by bioinformatic analysis. The expression levels of DEK at both mRNA and protein levels were determined by qRT-PCR and Western blot, respectively. Luciferase assays were carried out to examine cell viabilities. Hoechst 33258 staining was used to detect cell apoptosis.

RESULTS

Our results demonstrated that the expression levels of miR-138 were increased in AD model, and DEK was a target of miR-138. Overexpression of miR-138 in SH-SY5Y cells obviously down-regulated the expression of DEK in SH-SY5Y cells, resulting in the inactivation of AKT and increased expression levels of proapoptotic caspase-3. MiR-138 mediated-suppression of DEK increased the susceptibility of cell apoptosis.

CONCLUSIONS

MicroRNA-138 promotes cell apoptosis of SH-SY5Y by targeting DEK in SH-SY5Y AD cell model. The regulation of miR-138 may contribute to AD via down-regulation of the DEK/AKT pathway.

Neuroprotective and Anti-Neuroinflammatory Effects of a Poisonous Plant Croton Tiglium Linn. Extract

Neuroinflammation is involved in various neurological diseases. Activated microglia secrete many pro-inflammatory factors and induce neuronal cell death. Thus, the inhibition of excessive proinflammatory activity of microglia leads to a therapeutic effect that alleviates the progression of neuronal degeneration. In this study, we investigated the effect of Croton tiglium (C. tiglium) Linn. extract (CTE) on the production of pro- and anti-inflammatory mediators in microglia and astrocytes via RT-PCR, Western blot, and nitric oxide assay. Neurotoxicity was measured by cell viability assay and GFP image analysis. Phagocytosis of microglia was measured using fluorescent zymosan particles. CTE significantly inhibited the production of neurotoxic inflammatory factors, including nitric oxide and tumor necrosis factor-α. In addition, CTE increased the production of the neurotrophic factor, brain-derived neurotrophic factor, and the M2 phenotype of microglia. The culture medium retained after CTE treatment increased the survival of neurons, thereby indicating the neuroprotective effect of CTE. Our findings indicated that CTE inhibited pro-inflammatory response and increased the neuroprotective ability of microglia. In conclusion, although CTE is known to be a poisonous plant and listed on the FDA poisonous plant database, it can be used as a medicine if the amount is properly controlled. Our results suggested the potential benefits of CTE as a therapeutic agent for different neurodegenerative disorders involving neuroinflammation.

MicroRNA sequencing of rat hippocampus and human biofluids identifies acute, chronic, focal and diffuse traumatic brain injuries

High-throughput sequencing technologies could improve diagnosis and classification of TBI subgroups. Because recent studies showed that circulating microRNAs (miRNAs) may serve as noninvasive markers of TBI, we performed miRNA-seq to study TBI-induced changes in rat hippocampal miRNAs up to one year post-injury. We used miRNA PCR arrays to interrogate differences in serum miRNAs using two rat models of TBI (controlled cortical impact [CCI] and fluid percussion injury [FPI]). The translational potential of our results was evaluated by miRNA-seq analysis of human control and TBI (acute and chronic) serum samples. Bioinformatic analyses were performed using Ingenuity Pathway Analysis, miRDB, and Qlucore Omics Explorer. Rat miRNA profiles identified TBI across all acute and chronic intervals. Rat CCI and FPI displayed distinct serum miRNA profiles. Human miRNA profiles identified TBI across all acute and chronic time points and, at 24 hours, discriminated between focal and diffuse injuries. In both species, predicted gene targets of differentially expressed miRNAs are involved in neuroplasticity, immune function and neurorestoration. Chronically dysregulated miRNAs (miR-451a, miR-30d-5p, miR-145-5p, miR-204-5p) are linked to psychiatric and neurodegenerative disorders. These data suggest that circulating miRNAs in biofluids can be used as "molecular fingerprints" to identify acute, chronic, focal or diffuse TBI and potentially, presence of neurodegenerative sequelae.

Investigation of key miRNAs and their target genes involved in cell apoptosis during intervertebral disc degeneration development using bioinformatics methods

BACKGROUND

The aim of this study was to identify important miRNAs and their target genes involved in cell apoptosis in intervertebral disc degeneration (IDD) patients.

METHODS

The dataset, GSE63492, was obtained from the gene expression omnibus platform. After preprocessing, the differentially expressed miRNAs (DEMs) and their target genes were identified using the Limma package and miRWalk2.0 database, respectively. The clusterProfiler package in R was used to perform functional enrichment analysis of these target genes. Subsequently, protein-protein interaction (PPI) network and subnet clusters of the coregulated genes were conducted using the STRING database and MCODE, respectively. Further, the co-regulatory network of the key miRNAs and PPI networks were visualized using Cytoscape. Finally, cell apoptosis-related pathways and the genes enriched in these pathways were identified.

RESULTS

The genes targeted by the upregulated (hsa-miR-302c-5p, hsa-miR-631, hsa-let-7f-1-3p, hsa-miR-3675-3p, and hsa-miR-585-3p) and downregulated miRNAs (hsa-miR-185-5p, hsa-miR-486-5p, hsa-miR-4306, and hsa-miR-4674) were interrelated with cell apoptosis-related pathways. MAPK1 and MAPK3 were targeted by hsa-miR-185-5p, while GSK3B was targeted hsa-miR-4306, hsa-miR-486-5p, hsa-miR-185-5p, hsa-let-7f-1-3p, and hsa-miR-631. Besides, MAPK3 and VEGFA were regulated by hsa-miR-3675-3p and hsa-miR-631, respectively.

CONCLUSIONS

The expression of GSK3B may be coregulated by miR-4306, miR-185-5p, miR-486-5p, hsa-let-7f-1-3p, and miR-631 and may affect IDD development. Besides, miR-185-5p and miR-3675-3p may control nucleus pulposus (NP) cell apoptosis through the MAPK signaling pathway in IDD patients. VEGFA expression may be regulated by miR-631, and help maintain NP cell survival in IDD patients. Our findings may help guide further research into the role of miRNAs in IDD progression.

Models of poststroke depression and assessments of core depressive symptoms in rodents: How to choose?

Our previous studies have indicated that depression and declined cognition have been involved in some neurodegenerative diseases including Stroke, Parkinson's diseases and Vascular Parkinsonism. Post-stroke depression (PSD) is the most common psychiatric disorder following a stroke and has high morbidity and mortality. Studies on PSD are increasingly common, but the specific mechanisms remain unknown. Current research mainly includes clinical and animal aspects. Questionnaires and peripheral blood examination are two of the most common methods used to study clinical PSD. The results of questionnaires are influenced by multiple factors such as disease history, education background, occupation, economic status, family relationships and social support. There are certain limitations to blood sample testing; for example, it is influenced by cerebrovascular diseases and some other disruptions of the internal environment. It is difficult for either method to fully clarify the pathophysiological mechanism of PSD. Animal models provide alternative methods to further understand the pathophysiological mechanisms of PSD, such as the involvement of neuronal circuits and cytokines. More than ten animal models of PSD have been developed, and new models are constantly being introduced. Therefore, it is important to choose the appropriate model for any given study. In this paper, we will discuss the characteristics of the different models of PSD and comment on the advantages and disadvantages of each model, drawing from research on model innovation. Finally, we briefly describe the current assessment methods for the core symptoms of PSD models, point out the shortcomings, and present the improved sucrose preference test as a rational evaluation of anhedonia.

An investigation of microRNA-103 and microRNA-107 as potential blood-based biomarkers for disease risk and progression of Alzheimer's disease

BACKGROUND

This study aimed to assess the correlation of circulating microRNA-103 (miR-103) and microRNA-107 (miR-107) with disease risk and cognitive impairment of Alzheimer's disease (AD).

METHODS

Plasma samples from 120 AD patients, 120 Parkinson's disease (PD) patients (served as disease control), and 120 healthy controls were collected for miR-103 and miR-107 detections using real-time quantitative polymerase chain reaction. Mini-Mental State Examination (MMSE) score was documented and was used to accordingly assess the dementia severity.

RESULTS

miR-103 expression was decreased in AD patients compared with PD patients and healthy controls, and receiver operating characteristic (ROC) curve analyses illustrated that it was able to differentiate AD patients from PD patients and healthy controls. Additionally, miR-103 positively correlated with MMSE score and negatively correlated with dementia severity in AD patients. miR-107 expression was lower in AD patients compared with healthy controls but similar between AD patients and PD patients, and ROC curve analyses revealed that it was able to differentiate AD patients from healthy controls but not AD patients from PD patients. miR-107 was positively correlated with MMSE score and negatively correlated with dementia severity in AD patients, while the correlation coefficient of miR-107 with MMSE score was lower than that of miR-103 with MMSE score. Besides, miR-103 was positively correlated with miR-107 in AD patients, PD patients, and healthy controls.

CONCLUSION

miR-103 may be a better choice than miR-107 to serve as a potential biomarker for disease risk and disease progression of AD.

Novel Insights on Systemic and Brain Aging, Stroke, Amyotrophic Lateral Sclerosis, and Alzheimer's Disease

The mechanisms that underlie the pathophysiology of aging, amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD) and stroke are not fully understood and have been the focus of intense and constant investigation worldwide. Studies that provide insights on aging and age-related disease mechanisms are critical for advancing novel therapies that promote successful aging and prevent or cure multiple age-related diseases. The April 2019 issue of the journal, "Aging & Disease" published a series of articles that confer fresh insights on numerous age-related conditions and diseases. The age-related topics include the detrimental effect of overweight on energy metabolism and muscle integrity, senoinflammation as the cause of neuroinflammation, the link between systemic C-reactive protein and brain white matter loss, the role of miR-34a in promoting healthy heart and brain, the potential of sirtuin 3 for reducing cardiac and pulmonary fibrosis, and the promise of statin therapy for ameliorating asymptomatic intracranial atherosclerotic stenosis. Additional aging-related articles highlighted the involvement of miR-181b-5p and high mobility group box-1 in hypertension, Yes-associated protein in cataract formation, multiple miRs and long noncoding RNAs in coronary artery disease development, the role of higher meat consumption on sleep problems, and the link between glycated hemoglobin and depression. The topics related to ALS suggested that individuals with higher education and living in a rural environment have a higher risk for developing ALS, and collagen XIX alpha 1 is a prognostic biomarker of ALS. The topics discussed on AD implied that extracellular amyloid β42 is likely the cause of intraneuronal neurofibrillary tangle accumulation in familial AD and traditional oriental concoctions may be useful for slowing down the progression of AD. The article on stroke suggested that inhibition of the complement system is likely helpful in promoting brain repair after ischemic stroke. The significance of the above findings for understanding the pathogenesis in aging, ALS, AD, and stroke, slowing down the progression of aging, ALS and AD, and promoting brain repair after stroke are discussed.

MiR-34a and stroke: Assessment of non-modifiable biological risk factors in cerebral ischemia

Aging of the nervous system, and the occurrence of age-related brain diseases such as stroke, are associated with changes to a variety of cellular processes controlled by many distinct genes. MicroRNAs (miRNAs), short non-coding functional RNAs that can induce translational repression or site-specific cleavage of numerous target mRNAs, have recently emerged as important regulators of cellular senescence, aging, and the response to neurological insult. Here, we focused on the assessment of the role of miR-34a in stroke. We noted increases in miR-34a expression in the blood of stroke patients as well as in blood and brain of mice subjected to experimental stroke. Our methodical genetic manipulation of miR-34a expression substantially impacted stroke-associated preclinical outcomes and we have in vitro evidence that these changes may be driven at least in part by disruptions to blood brain barrier integrity and mitochondrial oxidative phosphorylation in endothelial cells. Finally, aging, independent of brain injury, appears to be associated with shifts in circulating miRNA profiles. Taken together, these data support a role for miRNAs, and specifically miR-34a, in brain aging and the physiological response to age-related neurological insult, and lay the groundwork for future investigation of this novel therapeutic target.