Oxidative stress mediated-alterations of the microRNA expression profile in mouse hippocampal neurons

Hippocampal microRNA-181a overexpression participates in anxiety and ethanol related behaviors via regulating the expression of SIRT-1

Understanding the molecular mechanisms underlying anxiety and ethanol-related behaviors is crucial for developing effective therapeutic interventions. This study identifies a novel role for microRNA miR-181a and its target, Sirtuin 1 (SIRT-1), in the hippocampus as contributors to anxiety-like behavior and voluntary ethanol intake. Using male and female C57BL/6 mice, we explored the causal relationship between hippocampal miR-181a expression and these behaviors. Lentivirus vectors were delivered into the hippocampus for focal miR-181a overexpression in mice. Then behaviors were observed by elevated plus maze (EPM) and open field (OF) tests. Results showed that the viral approach employed to overexpress miR-181a, in the hippocampus, resulted in increased anxiety-like behavior in the EPM and OF tests. Additionally, miR-181a overexpression exacerbated voluntary ethanol intake and preference in the two-bottle choice paradigm without affecting saccharin or quinine consumption. Mechanistically, miR-181a gain-of-function reduced SIRT-1 expression in the hippocampus. These findings demonstrate that miR-181a upregulation in the hippocampus promotes anxiety and ethanol-related behaviors, likely through SIRT-1 repression. This work highlights miR-181a as a key molecular mediator in the epigenetic regulation of mood disorders and ethanol consumption.

MicroRNAs: pioneering regulators in Alzheimer's disease pathogenesis, diagnosis, and therapy

This article delves into Alzheimer's disease (AD), a prevalent neurodegenerative condition primarily affecting the elderly. It is characterized by progressive memory and cognitive impairments, severely disrupting daily life. Recent research highlights the potential involvement of microRNAs in the pathogenesis of AD. MicroRNAs (MiRNAs), short non-coding RNAs comprising 20-24 nucleotides, significantly influence gene regulation by hindering translation or promoting degradation of target genes. This review explores the role of specific miRNAs in AD progression, focusing on their impact on β-amyloid (Aβ) peptide accumulation, intracellular aggregation of hyperphosphorylated tau proteins, mitochondrial dysfunction, neuroinflammation, oxidative stress, and the expression of the APOE4 gene. Our insights contribute to understanding AD's pathology, offering new avenues for identifying diagnostic markers and developing novel therapeutic targets.

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.

MicroRNAs and MAPKs: Evidence of These Molecular Interactions in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder known to be the leading cause of dementia worldwide. Many microRNAs (miRNAs) were found deregulated in the brain or blood of AD patients, suggesting a possible key role in different stages of neurodegeneration. In particular, mitogen-activated protein kinases (MAPK) signaling can be impaired by miRNA dysregulation during AD. Indeed, the aberrant MAPK pathway may facilitate the development of amyloid-beta (Aβ) and Tau pathology, oxidative stress, neuroinflammation, and brain cell death. The aim of this review was to describe the molecular interactions between miRNAs and MAPKs during AD pathogenesis by selecting evidence from experimental AD models. Publications ranging from 2010 to 2023 were considered, based on PubMed and Web of Science databases. According to obtained data, several miRNA deregulations may regulate MAPK signaling in different stages of AD and conversely. Moreover, overexpressing or silencing miRNAs involved in MAPK regulation was seen to improve cognitive deficits in AD animal models. In particular, miR-132 is of particular interest due to its neuroprotective functions by inhibiting Aβ and Tau depositions, as well as oxidative stress, through ERK/MAPK1 signaling modulation. However, further investigations are required to confirm and implement these promising results.

MiR-29c Inhibits TNF-α-Induced ROS Production and Apoptosis in Mouse Hippocampal HT22 Cell Line

Recent reports have suggested that abnormal miR-29c expression in hippocampus have been implicated in the pathophysiology of some neurodegenerative and neuropsychiatric diseases. However, the underlying effect of miR-29c in regulating hippocampal neuronal function is not clear. In this study, HT22 cells were infected with lentivirus containing miR-29c or miR-29c sponge. Cell counting kit-8 (CCK8) and lactate dehydrogenase (LDH) assay kit were applied to evaluate cell viability and toxicity before and after TNF-α administration. Reactive oxygen species (ROS) generation and mitochondrial membrane potential (MMP) were measured with fluorescent probes. Hoechst 33258 staining and TUNEL assay were used to evaluate cell apoptosis. The expression of key mRNA/proteins (TNFR1, Bcl-2, Bax, TRADD, FADD, caspase-3, -8 and -9) in the apoptosis pathway was detected by PCR or WB. In addition, the protein expression of microtubule-associated protein-2 (MAP-2), nerve growth-associated protein 43 (GAP-43) and synapsin-1 (SYN-1) was detected by WB. As a result, we found that miR-29c overexpression could improve cell viability, attenuate LDH release, reduce ROS production and inhibit MMP depolarization in TNF-α-treated HT22 cells. Furthermore, miR-29c overexpression was found to decrease apoptotic rate, along with decreased expression of Bax, cleaved caspase-3, cleaved caspase-9, and increased expression of Bcl-2 in TNF-α-treated HT22 cells. However, miR-29c sponge exhibited an opposite effects. In addition, in TNF-α-treated HT22 cells, miR-29c overexpression could decrease the expressions of TNFR1, TRADD, FADD and cleaved caspase-8. However, in HT22 cells transfected with miR-29c sponge, TNF-α-induced the expressions of TNFR1, TRADD, FADD and cleaved caspase-8 was significantly exacerbated. At last, TNF-α-induced the decreased expression of MAP-2, GAP-43 and SYN-1 was reversed by miR-29c but exacerbated by miR-29c sponge. Overall, our study demonstrated that miR-29c protects against TNF-α-induced HT22 cells injury through alleviating ROS production and reduce neuronal apoptosis. Therefore, miR-29c might be a potential therapeutic agent for TNF-α accumulation and toxicity-related brain diseases.

Antagonistic effect of selenium on mercuric chloride in the central immune organs of chickens: The role of microRNA-183/135b-FOXO1/TXNIP/NLRP3 inflammasome axis

Mercury (Hg) is a persistent environmental and industrial pollutant that accumulated in the body and induces oxidative stress and inflammation damage. Selenium (Se) has been reported to antagonize immune organs damage caused by heavy metals. Here, we aimed to investigate the prevent effect of Se on mercuric chloride (HgCl₂ )-induced thymus and bursa of Fabricius (BF) damage in chickens. The results showed that HgCl₂ caused immunosuppression by reducing the relative weight, cortical area of the thymus and BF, and the number of peripheral blood lymphocytes. Meanwhile, HgCl₂ induced oxidative stress and imbalance in cytokines expression in the thymus and BF. Further, we found that thioredoxin-interacting protein (TXNIP) and the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome mediated HgCl₂ -induced oxidative stress and inflammation. Mechanically, the targeting and inhibitory effect of microRNA (miR)-135b/183 on forkhead box O1 (FOXO1) were an upstream event for HgCl₂ -activated TXNIP/NLRP3 inflammasome pathway. Most importantly, Se effectively attenuated the aforementioned damage in the thymus and BF caused by HgCl₂ and inhibited the TXNIP/NLRP3 inflammasome pathway by reversing the expression of FOXO1 through inhibiting miR-135b/183. In conclusion, the miR-135b/183-FOXO1/TXNIP/NLRP3 inflammasome axis might be a novel mechanism for Se to antagonize HgCl₂ -induced oxidative stress and inflammation in the central immune organs of chickens.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Bisphenol A induces miR-708-5p through an ER stress-mediated mechanism altering neuronatin and neuropeptide Y expression in hypothalamic neuronal models

Bisphenol A (BPA) is an endocrine disrupting chemical that promotes obesity. It acts on the hypothalamus by increasing expression of the orexigenic neuropeptides, Npy and Agrp. Exactly how BPA dysregulates energy homeostasis is not completely clear. Since microRNAs (miRNA) have emerged as crucial weight regulators, the question of whether BPA could alter hypothalamic miRNA profiles was examined. Treatment of the mHypoA-59 cell line with 100 μM BPA altered a specific subset of miRNAs, and the most upregulated was miR-708-5p. BPA was found to increase the levels of miR-708-5p, and its parent gene Odz4, through the ER stress-related protein Chop. Overexpression of an miR-708-5p mimic resulted in a reduction of neuronatin, a proteolipid whose loss of expression is associated with obesity, and an increase in orexigenic Npy expression, thus potentially increasing feeding through converging regulatory pathways. Therefore, hypothalamic exposure to BPA can increase miR-708-5p that controls neuropeptides directly linked to obesity.

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.

Adaptive and Biological Responses of Buffalo Granulosa Cells Exposed to Heat Stress under In Vitro Condition

Simple Summary

The pertinent consequences of global warming substantially affect both animal productivity and fertility. Noteworthy, tropical and subtropical animal breeds are productively suited to hot climate conditions. Therefore studying the physiological changes accompanying high temperature, especially in tropically adapted species such as buffalo, will help in understanding the mechanisms that the animal use to accomplish the necessary functions efficiently. Concerning fertility-related activity, granulosa cells are important for the regulation of ovarian function and the completion of oocyte maturation. In this study, the buffalo granulosa cells were examined for their viability, physiological and molecular responses under in vitro heat stress conditions. Buffalo granulosa cells displayed different adaptive responses, at the physiological and molecular levels, to the different heat stress conditions. At 40.5 °C, granulosa cells exhibited a functional persistence compared to the control and other heat-treated groups. These results will provide insights into ways that tropically adapted breeds may be able to maintain better reproductive function when exposed to heat stress compared to temperate breeds.

Abstract

The steroidogenesis capacity and adaptive response of follicular granulosa cells (GCs) to heat stress were assessed together with the underlying regulating molecular mechanisms in Egyptian buffalo. In vitro cultured GCs were exposed to heat stress treatments at 39.5, 40.5, or 41.5 °C for the final 24 h of the culture period (7 days), while the control group was kept under normal conditions (37 °C). Comparable viability was observed between the control and heat-treated GCs at 39.5 and 40.5 °C. A higher release of E2, P4 and IGF-1 was observed in the 40.5 °C group compared with the 39.5 or 41.5 °C groups. The total antioxidant capacity was higher in response to heat stress at 39.5 °C. At 40.5 °C, a significant upregulation pattern was found in the expression of the stress resistance transcripts (SOD2 and NFE2L2) and of CPT2. The relative abundance of ATP5F1A was significantly downregulated for all heat-treated groups compared to the control, while TNFα was downregulated in GCs at 39.5 °C. Expression analyses of stress-related miRNAs (miR-1246, miR-181a and miR-27b) exhibited a significant downregulation in the 40.5 °C group compared to the control, whereas miR-708 was upregulated in the 39.5 and 40.5 °C groups. In conclusion, buffalo GCs exhibited different adaptive responses, to the different heat stress conditions. The integration mechanism between the molecular and secretory actions of the GCs cultured at 40.5 °C might provide possible insights into the biological mechanism through which buffalo GCs react to heat stress.

RNA and Oxidative Stress in Alzheimer's Disease: Focus on microRNAs

Oxidative stress (OS) is one of the major pathomechanisms of Alzheimer's disease (AD), which is closely associated with other key events in neurodegeneration such as mitochondrial dysfunction, inflammation, metal dysregulation, and protein misfolding. Oxidized RNAs are identified in brains of AD patients at the prodromal stage. Indeed, oxidized mRNA, rRNA, and tRNA lead to retarded or aberrant protein synthesis. OS interferes with not only these translational machineries but also regulatory mechanisms of noncoding RNAs, especially microRNAs (miRNAs). MiRNAs can be oxidized, which causes misrecognizing target mRNAs. Moreover, OS affects the expression of multiple miRNAs, and conversely, miRNAs regulate many genes involved in the OS response. Intriguingly, several miRNAs embedded in upstream regulators or downstream targets of OS are involved also in neurodegenerative pathways in AD. Specifically, seven upregulated miRNAs (miR-125b, miR-146a, miR-200c, miR-26b, miR-30e, miR-34a, miR-34c) and three downregulated miRNAs (miR-107, miR-210, miR-485), all of which are associated with OS, are found in vulnerable brain regions of AD at the prodromal stage. Growing evidence suggests that altered miRNAs may serve as targets for developing diagnostic or therapeutic tools for early-stage AD. Focusing on a neuroprotective transcriptional repressor, REST, and the concept of hormesis that are relevant to the OS response may provide clues to help us understand the role of the miRNA system in cellular and organismal adaptive mechanisms to OS.

RAGE signaling is required for AMPA receptor dysfunction in the hippocampus of hyperglycemic mice

Diabetes in humans has been associated for a long time with cognitive dysfunction. In rodent animal models, cognitive dysfunction can manifest as impaired hippocampal synaptic plasticity. Particular attention has been concentrated on the receptor for advanced glycation end products (RAGE), which is implicated in multiple diabetic complications involving the development of vascular and peripheral nerve abnormalities. In this study, we hypothesize that RAGE signaling alters glutamate receptor function and expression, impairing synaptic transmission in the hippocampus. Using preparations of hippocampal slices from male mice, we show a RAGE-dependent decrease in long-term potentiation (LTP) and an increase in paired-pulse facilitation (PPF) following streptozotocin (STZ)-induced diabetes. Consistently, in hippocampal cultures from male and female neonatal mice, high glucose caused a RAGE-dependent reduction of AMPA- but not NMDA-evoked currents, and an increase in cytosolic reactive oxygen species (ROS). Consistently, when cultures were co-treated with high glucose and the RAGE antagonist FPS-ZM1, AMPA-evoked currents were unchanged. Hippocampi from STZ-induced hyperglycemic wild type (WT) mice showed increased RAGE expression concomitant with a decrease of both expression and phosphorylation (Ser 831 and 845) of the AMPA GluA1 subunit. We found these changes correlated to activation of the MAPK pathway, consistent with decreased pJNK/JNK ratio and the JNK kinase, pMEK7. As no changes in expression or phosphorylation of regulatory proteins were observed in hippocampi from STZ-induced hyperglycemic RAGE-KO mice, we report a RAGE-dependent impairment in the hippocampi of hyperglycemic WT mice, with reduced AMPA receptor expression/function and LTP deficits.

Up-regulation of miR-135b expression induced by oxidative stress promotes the apoptosis of renal tubular epithelial cells under high glucose condition

This study aimed to investigate the role and underlying mechanism of miR-135b in high glucose-induced oxidative stress of renal tubular epithelial cells. Here, in vivo experiments found that compared to the control group, miR-135b expression was significantly up-regulated in the diabetes group, whereas BMP7 mRNA and protein levels were down-regulated. In high glucose-treated renal tubular epithelial cells (HK-2) in vitro, oxidative stress was induced, which up-regulated miR-135b expression. In addition, the regulation of miR-135b on BMP7 expression was confirmed in HK-2 cells. Under high glucose conditions, oxidative stress promoted the apoptosis of HK-2 cells through the up-regulation of miR-135b expression. In vivo experiments indicated that interference with miR-135b improved renal function in mice with diabetic nephropathy. In conclusion, these results indicated that the up-regulation of miR-135b expression induced by oxidative stress promotes the apoptosis of HK-2 cells under high glucose conditions.

MiR-708 inhibits MC3T3-E1 cells against H2O2-induced apoptosis through targeting PTEN

Background

The dysregulation of proliferation and apoptosis plays a significant role in the pathogenesis of postmenopausal osteoporosis (PO). MicroRNAs play an important role in regulating apoptosis of MC3T3-E1 cells. However, the role and potential mechanism of miR-708 for regulating H₂O₂-induced apoptosis is unknown. This study aimed to investigate the protective function of miR-708 in H₂O₂-induced apoptosis of MC3T3-E1 osteoblasts.

Methods

MC3T3-E1 was co-cultured with H₂O₂ for 8 h, then, flow cytometry, malondialdehyde (MDA), and glutathione peroxidase (Gpx) levels were measured to establish the oxidative model. MiRNA microarray was performed to assess differentially expressed miRNAs between control and H₂O₂-treated MC3T3-E1 cells. We then performed RT-PCR to identify the relative expression of miR-708 and PTEN. After transfected MC3T3-E1 with miR-708 mimics, flow cytometry, MDA, and Gpx level were performed to identify the apoptosis rate and oxidative stress in these groups. Furthermore, we small interfering RNA of PTEN to identify the role of PTEN in H₂O₂-induced apoptosis of MC3T3-E1 cells.

Results

H₂O₂ (100 nM) could significantly induce the apoptosis of MC3T3-E1 cells. Moreover, H₂O₂ could significantly increase the MDA level and downregulated Gpx level. RT-PCR found that H₂O₂ significantly decrease the level of miR-708. Compared with H₂O₂ group, H₂O₂ + miR-708 mimic significantly decreased the apoptosis rate.

Conclusions

miR-708 plays a protective role in H₂O₂-induced MC3T3-E1 osteoblasts apoptosis and its protective effect is proceeded by regulating ROS level and PTEN expression level.

MicroRNAs in the regulation of cellular redox status and its implications in myocardial ischemia-reperfusion injury

MicroRNAs (miRNAs) are small RNAs that do not encode for proteins and play key roles in the regulation of gene expression. miRNAs are involved in a comprehensive range of biological processes such as cell cycle control, apoptosis, and several developmental and physiological processes. Oxidative stress can affect the expression levels of multiple miRNAs and, conversely, miRNAs may regulate the expression of redox sensors, alter critical components of the cellular antioxidants, interact with the proteasome, and affect DNA repair systems. The number of publications identifying redox-sensitive miRNAs has increased significantly over the last few years, and some miRNA targets such as Nrf2, SIRT1 and NF-κB have been identified. The complex interplay between miRNAs and ROS is discussed together with their role in myocardial ischemia-reperfusion injury and the potential use of circulating miRNAs as biomarkers of myocardial infarction. Detailed knowledge of redox-sensitive miRNAs is needed to be able to effectively use individual compounds or sets of miRNA-modulating compounds to improve the health-related outcomes associated with different diseases.

Down-Regulation of miR-23a-3p Mediates Irradiation-Induced Neuronal Apoptosis

Radiation-induced central nervous system toxicity is a significant risk factor for patients receiving cancer radiotherapy. Surprisingly, the mechanisms responsible for the DNA damage-triggered neuronal cell death following irradiation have yet to be deciphered. Using primary cortical neuronal cultures in vitro, we demonstrated that X-ray exposure induces the mitochondrial pathway of intrinsic apoptosis and that miR-23a-3p plays a significant role in the regulation of this process. Primary cortical neurons exposed to irradiation show the activation of DNA-damage response pathways, including the sequential phosphorylation of ATM kinase, histone H2AX, and p53. This is followed by the p53-dependent up-regulation of the pro-apoptotic Bcl2 family molecules, including the BH3-only molecules PUMA, Noxa, and Bim, leading to mitochondrial outer membrane permeabilization (MOMP) and the release of cytochrome c, which activates caspase-dependent apoptosis. miR-23a-3p, a negative regulator of specific pro-apoptotic Bcl-2 family molecules, is rapidly decreased after neuronal irradiation. By increasing the degradation of PUMA and Noxa mRNAs in the RNA-induced silencing complex (RISC), the administration of the miR-23a-3p mimic inhibits the irradiation-induced up-regulation of Noxa and Puma. These changes result in an attenuation of apoptotic processes such as MOMP, the release of cytochrome c and caspases activation, and a reduction in neuronal cell death. The neuroprotective effects of miR-23a-3p administration may not only involve the direct inhibition of pro-apoptotic Bcl-2 molecules downstream of p53 but also include the attenuation of secondary DNA damage upstream of p53. Importantly, we demonstrated that brain irradiation in vivo results in the down-regulation of miR-23a-3p and the elevation of pro-apoptotic Bcl2-family molecules PUMA, Noxa, and Bax, not only broadly in the cortex and hippocampus, except for Bax, which was up-regulated only in the hippocampus but also selectively in isolated neuronal populations from the irradiated brain. Overall, our data suggest that miR-23a-3p down-regulation contributes to irradiation-induced intrinsic pathways of neuronal apoptosis. These regulated pathways of neurodegeneration may be the target of effective neuroprotective strategies using miR-23a-3p mimics to block their development and increase neuronal survival after irradiation.

Role of the Glyoxalase System in Alzheimer's Disease

Alzheimer's disease (AD) is an insidious and progressive neurodegenerative disease. The main pathological features of AD are the formation of amyloid-β deposits in the anterior cerebral cortex and hippocampus as well as the formation of intracellular neurofibrillary tangles. Thus far, accumulating evidence shows that glycation is closely related to AD. As a final product resulting from the crosslinking of a reducing sugar or other reactive carbonyls and a protein, the advanced glycation end products have been found to be associated with the formation of amyloid-β and neurofibrillary tangles in AD. As a saccharification inhibitor, the glyoxalase system and its substrate methylglyoxal (MG) were certified to be associated with AD onset and development. As an active substance of AGEs, MG could cause direct or indirect damage to nerve cells and tissues. MG is converted to D-lactic acid after decomposition by the glyoxalase system. Under normal circumstances, MG metabolism is in a dynamic equilibrium, whereas MG accumulates in cells in the case of aging or pathological states. Studies have shown that increasing glyoxalase activity and reducing the MG level can inhibit the generation of oxidative stress and AGEs, thereby alleviating the symptoms and signs of AD to some extent. This paper focuses on the relevant mechanisms of action of the glyoxalase system and MG in the pathogenesis of AD, as well as the potential of inhibiting the production of advanced glycation end products in the treatment of AD.

Understanding Epigenetics in the Neurodegeneration of Alzheimer's Disease: SAMP8 Mouse Model

Epigenetics is emerging as the missing link among genetic inheritance, environmental influences, and body and brain health status. In the brain, specific changes in nucleic acids or their associated proteins in neurons and glial cells might imprint differential patterns of gene activation that will favor either cognitive enhancement or cognitive loss for more than one generation. Furthermore, derangement of age-related epigenetic signaling is appearing as a significant risk factor for illnesses of aging, including neurodegeneration and Alzheimer’s disease (AD). In addition, better knowledge of epigenetic mechanisms might provide hints and clues in the triggering and progression of AD. Intense research in experimental models suggests that molecular interventions for modulating epigenetic mechanisms might have therapeutic applications to promote cognitive maintenance through an advanced age. The SAMP8 mouse is a senescence model with AD traits in which the study of epigenetic alterations may unveil epigenetic therapies against the AD.

MicroRNA Expression is Associated with Sepsis Disorders in Critically Ill Polytrauma Patients

A critically ill polytrauma patient is one of the most complex cases to be admitted to the intensive care unit, due to both the primary traumatic complications and the secondary post-traumatic interactions. From a molecular, genetic, and epigenetic point of view, numerous biochemical interactions are responsible for the deterioration of the clinical status of a patient, and increased mortality rates. From a molecular viewpoint, microRNAs are one of the most complex macromolecular systems due to the numerous modular reactions and interactions that they are involved in. Regarding the expression and activity of microRNAs in sepsis, their usefulness has reached new levels of significance. MicroRNAs can be used both as an early biomarker for sepsis, and as a therapeutic target because of their ability to block the complex reactions involved in the initiation, maintenance, and augmentation of the clinical status.

MicroRNA-135b-5p prevents oxygen-glucose deprivation and reoxygenation-induced neuronal injury through regulation of the GSK-3β/Nrf2/ARE signaling pathway

INTRODUCTION

MicroRNAs (miRNAs) are emerging as critical regulators in the pathological process of cerebral ischemia/reperfusion injury. miRNAs play an important role in regulating neuronal survival. miR-135b-5p has been reported as an important miRNA in regulating cell apoptosis. However, the role of miR-135b-5p in regulating neuronal survival remains poorly understood. Here, we aimed to investigate the role of miR-135b-5p in cerebral ischemia/ reperfusion using an in vitro model of oxygen-glucose deprivation and reoxygenation-(OGD/R) induced neuron injury.

MATERIAL AND METHODS

miRNA, mRNA and protein expression was detected by real-time quantitative polymerase chain reaction and Western blot. Cell viability was detected by cell counting kit-8 and lactate dehydrogenase assays. Cell apoptosis was detected by caspase-3 activity assay. Oxidative stress was determined using commercial kits. The target of miR-135b-5p was confirmed by dual-luciferase reporter assay.

RESULTS

We found that miR-135b-5p expression was significantly decreased in hippocampal neurons receiving OGD/R treatment. Overexpression of miR-135b-5p markedly alleviated OGD/R-induced cell injury and oxidative stress, whereas suppression of miR-135b-5p showed the opposite effects. We observed that miR-135b-5p directly targeted the 3'-untranslated region of glycogen synthase kinase-3β (GSK-3β). We found that miR-135b-5p negatively regulates the expression of GSK-3β in hippocampal neurons. Moreover, miR-135b-5p overexpression promotes activation of nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling. However, the restoration of GSK-3β expression significantly reversed the protective effects of miR-135b-5p overexpression.

CONCLUSIONS

Overall, our results suggest that miR-135b-5p protects neurons against OGD/R-induced injury through downregulation of GSK-3β and promotion of the Nrf2/ARE signaling pathway-mediated antioxidant responses.

miR200-regulated CXCL12β promotes fibroblast heterogeneity and immunosuppression in ovarian cancers

High-grade serous ovarian cancers (HGSOC) have been subdivided into molecular subtypes. The mesenchymal HGSOC subgroup, defined by stromal-related gene signatures, is invariably associated with poor patient survival. We demonstrate that stroma exerts a key function in mesenchymal HGSOC. We highlight stromal heterogeneity in HGSOC by identifying four subsets of carcinoma-associated fibroblasts (CAF-S1-4). Mesenchymal HGSOC show high content in CAF-S1 fibroblasts, which exhibit immunosuppressive functions by increasing attraction, survival, and differentiation of CD25⁺FOXP3⁺ T lymphocytes. The beta isoform of the CXCL12 chemokine (CXCL12β) specifically accumulates in the immunosuppressive CAF-S1 subset through a miR-141/200a dependent-mechanism. Moreover, CXCL12β expression in CAF-S1 cells plays a crucial role in CAF-S1 immunosuppressive activity and is a reliable prognosis factor in HGSOC, in contrast to CXCL12α. Thus, our data highlight the differential regulation of the CXCL12α and CXCL12β isoforms in HGSOC, and reveal a CXCL12β-associated stromal heterogeneity and immunosuppressive environment in mesenchymal HGSOC.

Increased Serum miR-206 Level Predicts Conversion from Amnestic Mild Cognitive Impairment to Alzheimer's Disease: A 5-Year Follow-up Study

Evidence suggests that individuals with amnestic mild cognitive impairment (aMCI) tend to progress to probable Alzheimer's disease (AD) with aging. This study was performed to examine whether circulating miRNAs could be potential predictors for the progression of aMCI to AD. A total of 458 patients with aMCI were included in this study, and the clinical data were collected at two time points: the baseline and the follow-up assessment. These aMCI patients were classified into two groups after 5 years: aMCI-stable group (n = 330) and AD-conversion group (n = 128). The expression of miR-206 and miR-132 and the levels of BDNF and SIRT1 in serum were detected using a quantitative real-time RT-PCR (qPCR) and the ELISA method, respectively. Kaplan-Meier method (Log-rank test) was used for univariate survival analysis. Cox proportional hazard model was used to estimate the prognostic value of miRNAs in conversion from aMCI to AD. At the baseline, serum levels of miR-206 in aMCI-AD group were significantly elevated compared to aMCI-aMCI group and the same trend was found at 5-year follow-up time point as well. There were no significant differences in serum levels of miR-132 between the conversion and non-conversion group at both time points. Kaplan-Meier analysis showed significant correlation between AD conversion and higher serum levels of miR-206 for aMCI patients (HR = 3.60, 95% CI: 2.51- 5.36, p < 0.001). Multivariate Cox regression analysis revealed that serum miR-206 and its target BDNF were significant independent predictors for AD conversion (HR = 4.22, p < 0.001). These results suggested that increased serum miR-206 level might be a potential predictor of conversion from aMCI to AD.

Elevation of Peripheral BDNF Promoter Methylation Predicts Conversion from Amnestic Mild Cognitive Impairment to Alzheimer's Disease: A 5-Year Longitudinal Study

Epigenetic aberrations have been identified as biomarkers to predict the risk of Alzheimer's disease (AD). This study aimed to evaluate whether altered DNA methylation status of BDNF promoter could be used as potential epigenetic biomarkers for predicting the progression from amnestic mild cognitive impairment (aMCI) to AD. A total of 506 aMCI patients and 728 cognitively normal controls were recruited in the cross-sectional analyses. Patients (n = 458) from aMCI cohort were classified into two groups after 5-year follow-up: aMCI-stable group (n = 330) and AD-conversion group (n = 128). DNA methylation of BDNF promoter was detected by bisulfite-PCR amplification and pyrosequencing. The DNA methylation levels of CpG1 and CpG2 in promoter I and CpG5 and CpG6 in promoter IV of BDNF gene were significantly higher in the aMCI group than in the control group at baseline and also were increased in the conversion group compared with the non-conversion group at 5-year follow up time point. CpG5 in BDNF promoter IV had the highest AUC of 0.910 (95% CI: 0.817-0.983, p < 0.05). Kaplan-Meier analysis showed a significant AD conversion propensity for aMCI patients with high methylation levels of CpG5 (HR = 1.96, 95% CI: 1.07-2.98, p < 0.001). Multivariate Cox regression analysis revealed elevated methylation status of CpG5 was a significant independent predictor for AD conversion (HR = 3.51, p = 0.013). These results suggest that elevation of peripheral BDNF promoter methylation might be used as potential epigenetic biomarkers for predicting the conversion from aMCI to AD.

Alteration in Intracellular Zn2+ Homeostasis as a Result of TRPM2 Channel Activation Contributes to ROS-Induced Hippocampal Neuronal Death

Transient receptor potential melastatin-related 2 (TRPM2) channel, a molecular sensor for reactive oxygen species (ROS), plays an important role in cognitive dysfunction associated with post-ischemia brain damage thought to result from ROS-induced TRPM2-dependent neuronal death during reperfusion. Emerging evidence further suggests that an alteration in the Zn²⁺ homeostasis is critical in ROS-induced TRPM2-dependent neuronal death. Here we applied genetic and pharmacological interventions to define the role of TRPM2 channel in ROS-induced neuronal death and explore the mechanisms contributing in the alteration in intracellular Zn²⁺ homeostasis in mouse hippocampal neurons. Exposure of neurons to 30–300 μM H₂O₂ for 2–24 h caused concentration/duration-dependent neuronal death, which was significantly suppressed, but not completely prevented, by TRPM2-knockout (TRPM2-KO) and pharmacological inhibition of the TRPM2 channel. H₂O₂-induced neuronal death was also attenuated by treatment with TPEN acting as a Zn²⁺ selective chelator. Single cell imaging demonstrated that H₂O₂ evoked a prominent increase in the intracellular Zn²⁺ concentration, which was completely prevented by TPEN as well as TRPM2-KO and inhibition of the TRPM2 channel. Furthermore, H₂O₂ induced lysosomal Zn²⁺ release and lysosomal dysfunction, and subsequent mitochondrial Zn²⁺ accumulation that provokes mitochondrial dysfunction and ROS generation. These H₂O₂-induced lysosomal/mitochondrial effects were prevented by TRPM2-KO or TPEN. Taken together, our results provide evidence to show that a dynamic alteration in the intracellular Zn²⁺ homeostasis as a result of activation of the TRPM2 channel contributes to ROS-induced hippocampal neuronal death.

miR-708-5p: a microRNA with emerging roles in cancer

MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression post-transcriptionally. They are crucial for normal development and maintaining homeostasis. Researchers have discovered that dysregulated miRNA expression contributes to many pathological conditions, including cancer. miRNAs can augment or suppress tumorigenesis based on their expression and transcribed targetome in various cell types. In recent years, researchers have begun to identify miRNAs commonly dysregulated in cancer. One recently identified miRNA, miR-708-5p, has been shown to have profound roles in promoting or suppressing oncogenesis in a myriad of solid and hematological tumors. This review highlights the diverse, sometimes controversial findings reported for miR-708-5p in cancer, and the importance of further exploring this exciting miRNA.

Neuromuscular electrical stimulation improves skeletal muscle regeneration through satellite cell fusion with myofibers in healthy elderly subjects

The aim of this study was to determine whether neuromuscular electrical stimulation (NMES) affects skeletal muscle regeneration through a reduction of oxidative status in satellite cells of healthy elderly subjects. Satellite cells from the vastus lateralis skeletal muscle of 12 healthy elderly subjects before and after 8 wk of NMES were allowed to proliferate to provide myogenic populations of adult stem cells [myogenic precursor cells (MPCs)]. These MPCs were then investigated in terms of their proliferation, their basal cytoplasmic free Ca2+concentrations, and their expression of myogenic regulatory factors ( PAX3, PAX7, MYF5, MYOD, and MYOG) and micro-RNAs (miR-1, miR-133a/b, and miR-206). The oxidative status of these MPCs was evaluated through superoxide anion production and superoxide dismutase and glutathione peroxidase activities. On dissected single skeletal myofibers, the nuclei were counted to determine the myonuclear density, the fiber phenotype, cross-sectional area, and tension developed. The MPCs obtained after NMES showed increased proliferation rates along with increased cytoplasmic free Ca2+concentrations and gene expression of MYOD and MYOG on MPCs. Muscle-specific miR-1, miR-133a/b, and miR-206 were upregulated. This NMES significantly reduced superoxide anion production, along with a trend to reduction of superoxide dismutase activity. The NMES-dependent stimulation of muscle regeneration enhanced satellite cell fusion with mature skeletal fibers. NMES improved the regenerative capacity of skeletal muscle in elderly subjects. Accordingly, the skeletal muscle strength and mobility of NMES-stimulated elderly subjects significantly improved. NMES may thus be further considered for clinical or ageing populations.

NEW & NOTEWORTHY The neuromuscular electrical stimulation (NMES) effect on skeletal muscle regeneration was assessed in healthy elderly subjects for the first time. NMES improved the regenerative capacity of skeletal muscle through increased myogenic precursor cell proliferation and fusion with mature myofibers. The increased cytoplasmic free Ca2+concentration along with MYOD, MYOG, and micro-RNA upregulation could be related to reduced O2·−production, which, in turn, favors myogenic regeneration. Accordingly, the skeletal muscle strength of NMES-stimulated lower limbs of healthy elderly subjects improved along with their mobility.

Anti-inflammatory effects of millet bran derived-bound polyphenols in LPS-induced HT-29 cell via ROS/miR-149/Akt/NF-κB signaling pathway

The pro-inflammatory and anti-inflammatory maladjustment has been acknowledged as one of the chief causations of inflammatory diseases and even cancers. Previous studies showed that plant-derived polyphenolic compounds were the most potent anti-oxidant and anti-inflammatory agents among all natural compounds. The present study indicates that bound polyphenols of inner shell (BPIS) from foxtail millet bran can display anti-inflammatory effects in LPS-induced HT-29 cells and in nude mice. Mechanistically, BPIS restrained the level of various pro-inflammatory cytokines (IL-1β, IL-6, IL-8), and enhanced the expression level of anti-inflammatory cytokine (IL-10) by blocking the nuclear factor-kappaB (NF-κB)-p65 nuclear translocation. Further, we found the elevated miR-149 expression by BPIS-induced ROS accumulation, directly targeted the Akt expression to block NF-κB nuclear translocation. Taken together, these novel findings provide new insights into the development of BPIS as an anti-inflammatory agent via the signaling cascade of ROS/miR-149/Akt/NF-κB axis.

Identification of Four Oxidative Stress-Responsive MicroRNAs, miR-34a-5p, miR-1915-3p, miR-638, and miR-150-3p, in Hepatocellular Carcinoma

Increasing evidence suggests that oxidative stress plays an essential role during carcinogenesis. However, the underlying mechanism between oxidative stress and carcinogenesis remains unknown. Recently, microRNAs (miRNAs) are revealed to be involved in oxidative stress response and carcinogenesis. This study aims to identify miRNAs in hepatocellular carcinoma (HCC) cells which might involve in oxidative stress response. An integrated analysis of miRNA expression signature was performed by employing robust rank aggregation (RRA) method, and four miRNAs (miR-34a-5p, miR-1915-3p, miR-638, and miR-150-3p) were identified as the oxidative stress-responsive miRNAs. Pathway enrichment analysis suggested that these four miRNAs played an important role in antiapoptosis process. Our data also revealed miR-34a-5p and miR-1915-3p, but not miR-150-3p and miR-638, were regulated by p53 in HCC cell lines under oxidative stress. In addition, clinical investigation revealed that these four miRNAs might be involved in oxidative stress response by targeting oxidative stress-related genes in HCC tissues. Kaplan-Meier analysis showed that these four miRNAs were associated with patients' overall survival. In conclusion, we identified four oxidative stress-responsive miRNAs, which were regulated by p53-dependent (miR-34a-5p and miR-1915-3p) and p53-independent pathway (miR-150-3p and miR-638). These four miRNAs may offer new strategy for HCC diagnosis and prognosis.

A novel fine tuning scheme of miR-200c in modulating lung cell redox homeostasis

Oxidative stress induces miR-200c, the predominant microRNA (miRNA) in lung tissues; however, the antioxidant role and biochemistry of such induction have not been clearly defined. Therefore, a lung adenocarcinoma cell line (A549) and a normal lung fibroblast (MRC-5) were used as models to determine the effects of miR-200c expression on lung antioxidant response. Hydrogen peroxide (H₂O₂) upregulated miR-200c, whose overexpression exacerbated the decrease in cell proliferation, retarded the progression of cells in the G2/M-phase, and increased oxidative stress upon H₂O₂ stimulation. The expression of three antioxidant proteins, superoxide dismutase (SOD)-2, haem oxygenase (HO)-1, and sirtuin (SIRT) 1, was reduced upon H₂O₂ stimulation in miR-200c-overexpressed A549 cells. This phenomenon of increased oxidative stress and antioxidant protein downregulation also occurs simultaneously in miR-200c overexpressed MRC-5 cells. Molecular analysis revealed that miR-200c inhibited the gene expression of HO-1 by directly targeting its 3'-untranslated region. The downregulation of SOD2 and SIRT1 by miR-200c was mediated through zinc finger E-box-binding homeobox 2 (ZEB2) and extracellular signal-regulated kinase 5 (ERK5) pathways, respectively, where knockdown of ZEB2 or ERK5 decreased the expression of SOD2 or SIRT1 in A549 cells. LNA anti-miR-200c transfection in A549 cells inhibited the endogenous miR-200c expression, resulting in increased expressions of antioxidant proteins, reduced oxidative stress and recovered cell proliferation upon H₂O₂ stimulation. These findings indicate that miR-200c fine-tuned the antioxidant response of the lung cells to oxidative stress through several pathways, and thus this study provides novel information concerning the role of miR-200c in modulating redox homeostasis of lung.

Integration of microRNAome, proteomics and metabolomics to analyze arsenic-induced malignant cell transformation

Long-term exposure to arsenic has been linked to tumorigenesis in different organs and tissues, such as skin; however, the detailed mechanism remains unclear. In this present study, we integrated “omics” including microRNAome, proteomics and metabolomics to investigate the potential molecular mechanisms. Compared with non-malignant human keratinocytes (HaCaT), twenty-six miRNAs were significantly altered in arsenic-induced transformed cells. Among these miRNAs, the differential expression of six miRNAs was confirmed using Q-RT-PCR, representing potential oxidative stress genes. Two-dimensional gel electrophoresis (2D-PAGE) and mass spectrometry (MS) were performed to identify the differential expression of proteins in arsenic-induced transformed cells, and twelve proteins were significantly changed. Several proteins were associated with oxidative stress and carcinogenesis including heat shock protein beta-1 (HSPB1), peroxiredoxin-2 (PRDX2). Using ultra-performance liquid chromatography and Q-TOF mass spectrometry (UPLC/Q-TOF MS), 68 metabolites including glutathione, fumaric acid, citric acid, phenylalanine, and tyrosine, related to redox metabolism, glutathione metabolism, citrate cycle, met cycle, phenylalanine and tyrosine metabolism were identified and quantified. Taken together, these results indicated that arsenic-induced transformed cells exhibit alterations in miRNA, protein and metabolite profiles providing novel insights into arsenic-induced cell malignant transformation and identifying early potential biomarkers for cutaneous squamous cell carcinoma induced by arsenic.

Evidence for Ancestral Programming of Resilience in a Two-Hit Stress Model

In a continuously stressful environment, the effects of recurrent prenatal stress (PS) may accumulate across generations and alter stress vulnerability and resilience. Here, we report in female rats that a family history of recurrent ancestral PS facilitates certain aspects of movement performance, and that these benefits are abolished by the experience of a second hit, induced by a silent ischemia during adulthood. Female F4-generation rats with and without a family history of cumulative multigenerational PS (MPS) were tested for skilled motor function before and after the induction of a minor ischemic insult by endothelin-1 infusion into the primary motor cortex. MPS resulted in improved skilled motor abilities and blunted hypothalamic-pituitary-adrenal (HPA) axis function compared to non-stressed rats. Deep sequencing revealed downregulation of miR-708 in MPS rats along with upregulation of its predicted target genes Mapk10 and Rasd2. Through miR-708 stress may regulate mitogen-activated protein kinase (MAPK) pathway activity. Hair trace elemental analysis revealed an increased Na/K ratio, which suggests a chronic shift in adrenal gland function. The ischemic lesion activated the HPA axis in MPS rats only; the lesion, however, abolished the advantage of MPS in skilled reaching. The findings indicate that MPS generates adaptive flexibility in movement, which is challenged by a second stressor, such as a neuropathological condition. Thus, a second “hit” by a stressor may limit behavioral flexibility and neural plasticity associated with ancestral stress.

Linking deregulation of non-coding RNA to the core pathophysiology of Alzheimer's disease: An integrative review

The human genome encodes a vast repertoire of protein non-coding RNAs (ncRNA), some specific to the brain. MicroRNAs, which interfere with the translation of target mRNAs, are of particular interest since their deregulation has been implicated in neurodegenerative disorders like Alzheimer's disease (AD). However, it remains challenging to link the complex body of observations on miRNAs and AD into a coherent framework. Using extensive graphical support, this article discusses how a diverse panoply of miRNAs convergently and divergently impact (and are impacted by) core pathophysiological processes underlying AD: neuroinflammation and oxidative stress; aberrant generation of β-amyloid-42 (Aβ42); anomalies in the production, cleavage and post-translational marking of Tau; impaired clearance of Aβ42 and Tau; perturbation of axonal organisation; disruption of synaptic plasticity; endoplasmic reticulum stress and the unfolded protein response; mitochondrial dysfunction; aberrant induction of cell cycle re-entry; and apoptotic loss of neurons. Intriguingly, some classes of miRNA provoke these cellular anomalies, whereas others act in a counter-regulatory, protective mode. Moreover, changes in levels of certain species of miRNA are a consequence of the above-mentioned anomalies. In addition to miRNAs, circular RNAs, piRNAs, long non-coding RNAs and other types of ncRNA are being increasingly implicated in AD. Overall, a complex mesh of deregulated and multi-tasking ncRNAs reciprocally interacts with core pathophysiological mechanisms underlying AD. Alterations in ncRNAs can be detected in CSF and the circulation as well as the brain and are showing promise as biomarkers, with the ultimate goal clinical exploitation as targets for novel modes of symptomatic and course-altering therapy.

The Influence of Spirulina platensis Filtrates on Caco-2 Proliferative Activity and Expression of Apoptosis-Related microRNAs and mRNA

Spirulina platensis (SP) is a blue-green microalga that has recently raised attention not only as a nutritional component, but also as a source of bioactivities that have therapeutic effects and may find application in medicine, including cancer treatment. In the present study we determined the cytotoxic effect of S. platensis filtrates (SPF) on human colon cancer cell line Caco-2. Three concentrations of SPF were tested-1.25%, 2.5%, and 5% (v/v). We have found that the highest concentration of SPF exerts the strongest anti-proliferative and pro-apoptotic effect on Caco-2 cultures. The SPF negatively affected the morphology of Caco-2 causing colony shrinking and significant inhibition of metabolic and proliferative activity of cells. The wound-healing assay showed that the SPF impaired migratory capabilities of Caco-2. This observation was consistent with lowered mRNA levels for metalloproteinases. Furthermore, SPF decreased the transcript level of pro-survival genes (cyclin D1, surviving, and c-Myc) and reduced the autocrine secretion of Wnt-10b. The cytotoxic effect of SPF involved the modulation of the Bax and Bcl-2 ratio and a decrease of mitochondrial activity, and was related with increased levels of intracellular reactive oxygen species (ROS) and nitric oxide (NO). Moreover, the SPF also caused an increased number of cells in the apoptotic sub-G0 phase and up-regulated expression of mir-145, simultaneously decreasing expression of mir-17 and 146. Obtained results indicate that SPF can be considered as an agent with anti-cancer properties that may be used for colon cancer prevention and treatment.

Genetic variation in the miR-708 gene and its binding targets in bipolar disorder

OBJECTIVE

rs12576775 was found to be associated with bipolar disorder (BD) in a genome-wide association study (GWAS). The GWAS signal implicates genes for the microRNAs miR-708 and miR-5579 and the first exon of the Odd Oz/ten-m homolog 4 gene (ODZ4). In the present study, miR-708, its surrounding region, and its targets were analyzed for potential BD-associated functional variants.

METHODS

The miR-708 gene and surrounding regions were screened for variation using high-resolution melting (HRM) analysis in 1099 cases of BD, followed by genotyping of rare variants in an enlarged sample of 2078 subjects with BD, 1303 subjects with schizophrenia, and 1355 healthy controls. Whole-genome sequencing data from 99 subjects with BD were analyzed for variation in potential miR-708 binding sites. The minor allele frequencies (MAFs) of these variants were compared with those reported in reference individuals.

RESULTS

Three variants detected by HRM were selected to be genotyped. rs754333774 was detected in three cases of BD, two cases of schizophrenia, and no controls. This variant is located 260 base pairs upstream from miR-708 and may play a role in controlling the expression of the miR. Four variants were identified in miR-708 targets binding sites. The MAFs of each of these variants were similar in BD and reference samples.

CONCLUSIONS

We report a single recurrent variant located near the miR-708 gene that may have a role in BD and schizophrenia susceptibility. These findings await replication in independent cohorts, as do functional analyses of the potential consequences of this variant.

Epigenetic Regulation of Oxidative Stress in Ischemic Stroke

The prevalence and incidence of stroke rises with life expectancy. However, except for the use of recombinant tissue-type plasminogen activator, the translation of new therapies for acute stroke from animal models into humans has been relatively unsuccessful. Oxidative DNA and protein damage following stroke is typically associated with cell death. Cause-effect relationships between reactive oxygen species and epigenetic modifications have been established in aging, cancer, acute pancreatitis, and fatty liver disease. In addition, epigenetic regulatory mechanisms during stroke recovery have been reviewed, with focuses mainly on neural apoptosis, necrosis, and neuroplasticity. However, oxidative stress-induced epigenetic regulation in vascular neural networks following stroke has not been sufficiently explored. Improved understanding of the epigenetic regulatory network upon oxidative stress may provide effective antioxidant approaches for treating stroke. In this review, we summarize the epigenetic events, including DNA methylation, histone modification, and microRNAs, that result from oxidative stress following experimental stroke in animal and cell models, and the ways in which epigenetic changes and their crosstalk influence the redox state in neurons, glia, and vascular endothelial cells, helping us to understand the foregone and vicious epigenetic regulation of oxidative stress in the vascular neural network following stroke.

Identification of a microRNA (miR-663a) induced by ER stress and its target gene PLOD3 by a combined microRNome and proteome approach

INTRODUCTION

MicroRNAs (miRs) regulate gene expression to support important physiological functions. Significant evidences suggest that miRs play a crucial role in many pathological events and in the cell response to various stresses.

METHODS

With the aim to identify new miRs induced by perturbation of intracellular calcium homeostasis, we analysed miR expression profiles of thapsigargin (TG)-treated cells by microarray. In order to identify miR-663a-regulated genes, we evaluated proteomic changes in miR-663a-overexpressing cells by two-dimensional differential in-gel electrophoresis coupled to mass spectrometric identification of the differentially represented proteins. Microarray and proteomic analyses were supported by biochemical validation.

RESULTS

Results of microarray revealed 24 differentially expressed miRs; among them, miR-663a turned out to be by ER stress and under the control of the PERK pathway of the unfolded protein response. Proteomic analysis revealed that PLOD3, which is the gene encoding for collagen-modifying lysyl hydroxylase 3 (LH3), is regulated by miR-663a. Luciferase reporter assays demonstrated that miR-663a indeed reduces LH3 expression by targeting to 3'-UTR of PLOD3 mRNA. Interestingly, miR-663a inhibition of LH3 expression generates reduced extracellular accumulation of type IV collagen, thus suggesting the involvement of miR-663a in modulating collagen 4 secretion in physiological conditions and in response to ER stress.

CONCLUSION

The finding of the ER stress-induced PERK-miR-663a pathway may have important implications in the understanding of the molecular mechanisms underlying the function of this miR in normal and/or pathological conditions.

Regulation of miR-200c/141 expression by intergenic DNA-looping and transcriptional read-through

The miR-200 family members have been implicated in stress responses and ovarian tumorigenesis. Here, we find that miR-200c/141 transcription is intimately linked to the transcription of the proximal upstream gene PTPN6 (SHP1) in all physiological conditions tested. PTPN6 and miR-200c/141 are transcriptionally co-regulated by two complementary mechanisms. First, a bypass of the regular PTPN6 polyadenylation signal allows the transcription of the downstream miR-200c/141. Second, the promoters of the PTPN6 and miR-200c/141 transcription units physically interact through a 3-dimensional DNA loop and exhibit similar epigenetic regulation. Our findings highlight that transcription of intergenic miRNAs is a novel outcome of transcriptional read-through and reveal a yet unexplored type of DNA loop associating two closely located promoters. These mechanisms have significant relevance in ovarian cancers and stress response, pathophysiological conditions in which miR-200c/141 exert key functions.

The miR-141/200 familly of micro RNAs control oxidative stress and impact on ovarian tumorigenesis. Here the authors show that the transcription of miR-200c/141 is regulated through transcriptional read-through of the upstream gene PTPN6, and DNA looping linking the PTPN6 and miR-200c/141 promoters.

Genome-wide analysis implicates microRNAs and their target genes in the development of bipolar disorder

Bipolar disorder (BD) is a severe and highly heritable neuropsychiatric disorder with a lifetime prevalence of 1%. Molecular genetic studies have identified the first BD susceptibility genes. However, the disease pathways remain largely unknown. Accumulating evidence suggests that microRNAs, a class of small noncoding RNAs, contribute to basic mechanisms underlying brain development and plasticity, suggesting their possible involvement in the pathogenesis of several psychiatric disorders, including BD. In the present study, gene-based analyses were performed for all known autosomal microRNAs using the largest genome-wide association data set of BD to date (9747 patients and 14 278 controls). Associated and brain-expressed microRNAs were then investigated in target gene and pathway analyses. Functional analyses of miR-499 and miR-708 were performed in rat hippocampal neurons. Ninety-eight of the six hundred nine investigated microRNAs showed nominally significant P-values, suggesting that BD-associated microRNAs might be enriched within known microRNA loci. After correction for multiple testing, nine microRNAs showed a significant association with BD. The most promising were miR-499, miR-708 and miR-1908. Target gene and pathway analyses revealed 18 significant canonical pathways, including brain development and neuron projection. For miR-499, four Bonferroni-corrected significant target genes were identified, including the genome-wide risk gene for psychiatric disorder CACNB2. First results of functional analyses in rat hippocampal neurons neither revealed nor excluded a major contribution of miR-499 or miR-708 to dendritic spine morphogenesis. The present results suggest that research is warranted to elucidate the precise involvement of microRNAs and their downstream pathways in BD.

MicroRNAs as biomarkers of resilience or vulnerability to stress

Identifying novel biomarkers of resilience or vulnerability to stress could provide valuable information for the prevention and treatment of stress-related psychiatric disorders. To investigate the utility of blood microRNAs as biomarkers of resilience or vulnerability to stress, microRNAs were assessed before and after 7days of chronic social defeat in rats. Additionally, microRNA profiles of two important stress-regulatory brain regions, the medial prefrontal cortex (mPFC) and basolateral amygdala (BLA), were assessed. Rats that displayed vulnerability to subsequent chronic stress exhibited reductions in circulating miR-24-2-5p, miR-27a-3p, miR-30e-5p, miR-3590-3p, miR-362-3p, and miR-532-5p levels. In contrast, rats that became resilient to stress displayed reduced levels of miR-139-5p, miR-28-3p, miR-326-3p, and miR-99b-5p compared to controls. In the mPFC, miR-126a-3p and miR-708-5p levels were higher in vulnerability compared to resilient rats. In the BLA, 77 microRNAs were significantly altered by stress but none were significantly different between resilient and vulnerable animals. These results provide proof-of-principle that assessment of circulating microRNAs is useful in identifying individuals who are vulnerable to the effects of future stress or individuals who have become resilient to the effects of stress. Furthermore, these data suggest that microRNAs in the mPFC but not in the BLA are regulators of resilience/vulnerability to stress.

Peroxynitrite-mediated glyoxalase I epigenetic inhibition drives apoptosis in airway epithelial cells exposed to crystalline silica via a novel mechanism involving argpyrimidine-modified Hsp70, JNK, and NF-κB

Glyoxalase I (Glo1) is a cellular defense enzyme involved in the detoxification of methylglyoxal (MG), a cytotoxic by-product of glycolysis, and MG-derived advanced glycation end products (AGEs). Argpyrimidine (AP), one of the major AGEs coming from MG modification of protein arginines, is a proapoptotic agent. Crystalline silica is a well-known occupational health hazard, responsible for a relevant number of pulmonary diseases. Exposure of cells to crystalline silica results in a number of complex biological responses, including apoptosis. The present study was aimed at investigating whether, and through which mechanism, Glo1 was involved in Min-U-Sil 5 crystalline silica-induced apoptosis. Apoptosis, by TdT-mediated dUTP nick-end labeling assay, and transcript and protein levels or enzymatic activity, by quantitative real-time PCR, Western blot, and spectrophotometric methods, respectively, were evaluated in human bronchial BEAS-2B cells exposed or not (control) to crystalline silica and also in experiments with appropriate inhibitors. Reactive oxygen species were evaluated by coumarin-7-boronic acid or Amplex red hydrogen peroxide/peroxidase methods for peroxynitrite (ONOO(-)) or hydrogen peroxide (H2O2) measurements, respectively. Our results showed that Min-U-Sil 5 crystalline silica induced a dramatic ONOO(-)-mediated inhibition of Glo1, leading to AP-modified Hsp70 protein accumulation that, in a mechanism involving JNK and NF-κB, triggered an apoptotic mitochondrial pathway. Inhibition of Glo1 occurred at both functional and transcriptional levels, the latter occurring via ERK1/2 MAPK and miRNA 101 involvement. Taken together, our data demonstrate that Glo1 is involved in the Min-U-Sil 5 crystalline silica-induced BEAS-2B cell mitochondrial apoptotic pathway via a novel mechanism involving Hsp70, JNK, and NF-κB. Because maintenance of an intact respiratory epithelium is a critically important determinant of normal respiratory function, the knowledge of the mechanisms underlying its disruption may provide insight into the genesis, and possibly the prevention, of a number of pathological conditions commonly occurring in silica dust occupational exposure.

The epigenetic dimension of Alzheimer's disease: causal, consequence, or curiosity?

Early-onset, familial Alzheimer's disease (AD) is rare and may be attributed to disease-causinq mutations. By contrast, late onset, sporadic (non-Mendelian) AD is far more prevalent and reflects the interaction of multiple genetic and environmental risk factors, together with the disruption of epigenetic mechanisms controlling gene expression. Accordingly, abnormal patterns of histone acetylation and methylation, as well as anomalies in global and promoter-specific DNA methylation, have been documented in AD patients, together with a deregulation of noncoding RNA. In transgenic mouse models for AD, epigenetic dysfunction is likewise apparent in cerebral tissue, and it has been directly linked to cognitive and behavioral deficits in functional studies. Importantly, epigenetic deregulation interfaces with core pathophysiological processes underlying AD: excess production of Aβ42, aberrant post-translational modification of tau, deficient neurotoxic protein clearance, axonal-synaptic dysfunction, mitochondrial-dependent apoptosis, and cell cycle re-entry. Reciprocally, DNA methylation, histone marks and the levels of diverse species of microRNA are modulated by Aβ42, oxidative stress and neuroinflammation. In conclusion, epigenetic mechanisms are broadly deregulated in AD mainly upstream, but also downstream, of key pathophysiological processes. While some epigenetic shifts oppose the evolution of AD, most appear to drive its progression. Epigenetic changes are of irrefutable importance for AD, but they await further elucidation from the perspectives of pathogenesis, biomarkers and potential treatment.

Pterostilbene and allopurinol reduce fructose-induced podocyte oxidative stress and inflammation via microRNA-377

High dietary fructose is an important causative factor in the development of metabolic syndrome-associated glomerular podocyte oxidative stress and injury. Here, we identified microRNA-377 (miR-377) as a biomarker of oxidative stress in renal cortex of fructose-fed rats, which correlated with podocyte injury and albuminuria in metabolic syndrome. Fructose feeding increased miR-377 expression, decreased superoxide dismutase (SOD) expression and activity, and caused O2(-) and H2O2 overproduction in kidney cortex or glomeruli of rats. This reactive oxygen species induction increased p38 MAPK phosphorylation and thioredoxin-interacting protein (TXNIP) expression and activated the NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome to produce interleukin-1β in kidney glomeruli of fructose-fed rats. These pathological processes were further evaluated in cultured differentiated podocytes exposed to 5mM fructose, or transfected with miR-377 mimic/inhibitor and TXNIP siRNA, or co-incubated with p38 MAPK inhibitor, demonstrating that miR-377 overexpression activates the O2(-)/p38 MAPK/TXNIP/NLRP3 inflammasome pathway to promote oxidative stress and inflammation in fructose-induced podocyte injury. Antioxidants pterostilbene and allopurinol were found to ameliorate fructose-induced hyperuricemia, podocyte injury, and albuminuria in rats. More importantly, pterostilbene and allopurinol inhibited podocyte miR-377 overexpression to increase SOD1 and SOD2 levels and suppress the O2(-)/p38 MAPK/TXNIP/NLRP3 inflammasome pathway activation in vivo and in vitro, consistent with the reduction of oxidative stress and inflammation. These findings suggest that miR-377 plays an important role in glomerular podocyte oxidative stress, inflammation, and injury driven by high fructose. Inhibition of miR-377 by antioxidants may be a promising therapeutic strategy for the prevention of metabolic syndrome-associated glomerular podocyte injury.

Heme oxygenase-1 modulates microRNA expression in cultured astroglia: implications for chronic brain disorders

BACKGROUND

Over-expression of the heme-degrading enzyme, heme oxygenase-1 (HO-1) promotes iron deposition, mitochondrial damage, and autophagy in astrocytes and enhances the vulnerability of nearby neuronal constituents to oxidative injury. These neuropathological features and aberrant brain microRNA (miRNA) expression patterns have been implicated in the etiopathogeneses of various neurodevelopmental and aging-related neurodegenerative disorders.

OBJECTIVE

To correlate glial HO-1 overexpression with altered miRNA patterns, which have been linked to the aforementioned "core" neuropathological features.

METHODS

miRNA microchip assays were performed on HMOX1- and sham-transfected primary rat astroglia and affected miRNAs were further validated by qPCR. The roles of the heme degradation products, carbon monoxide (CO), iron (Fe) and bilirubin on miRNA expression were assessed and salient mRNA targets of the impacted miRNAs were ascertained.

RESULTS

In HMOX1-transfected astrocytes, rno-miR-140*, rno-miR-17, and rno-miR-16 were significantly up-regulated, and rno-miR-297, rno-miR-206, rno-miR-187, rno-miR-181a, rno-miR-138 and rno-miR-29c were down-regulated, compared to sham-transfected controls. CO and Fe were implicated in the HMOX1 effects, whereas bilirubin was inert or counteracted the HMOX1-related changes. mRNA levels of Ngfr, Vglut1, Mapk3, Tnf-α, and Sirt1, known targets of the down-regulated miRNAs and abnormal in various human brain disorders, were significantly increased in the HMOX-1-transfected astrocytes.

CONCLUSIONS

In chronic CNS disorders, altered expression of salient miRNAs and their mRNA targets may contribute to the neural damage accruing from the over-expression of glial HO-1.

MicroRNA-135b regulates ERα, AR and HIF1AN and affects breast and prostate cancer cell growth

MicroRNAs (miRNAs) regulate a wide range of cellular signaling pathways and biological processes in both physiological and pathological states such as cancer. We have previously identified miR-135b as a direct regulator of androgen receptor (AR) protein level in prostate cancer (PCa). We wanted to further explore the relationship of miR-135b to hormonal receptors, particularly estrogen receptor α (ERα). Here we show that miR-135b expression is lower in ERα-positive breast tumors as compared to ERα-negative samples in two independent breast cancer (BCa) patient cohorts (101 and 1302 samples). Additionally, the miR-135b expression is higher in AR-low PCa patient samples (47 samples). We identify ERα as a novel miR-135b target by demonstrating miR-135b binding to the 3'UTR of the ERα and decreased ERα protein and mRNA level upon miR-135b overexpression in BCa cells. MiR-135b reduces proliferation of ERα-positive BCa cells MCF-7 and BT-474 as well as AR-positive PCa cells LNCaP and 22Rv1 when grown in 2D. To identify other genes regulated by miR-135b we performed gene expression studies and found a link to the hypoxia inducible factor 1α (HIF1α) pathway. We show that miR-135b influences the protein level of the inhibitor for hypoxia inducible factor 1α (HIF1AN) and is able to bind to HIF1AN 3'UTR. Our study demonstrates that miR-135b regulates ERα, AR and HIF1AN protein levels through interaction with their 3'UTR regions, and proliferation in ERα-positive BCa and AR-positive PCa cells.