The interplay between microRNAs and histone deacetylases in neurological diseases

Molecular mechanism of HDAC6-mediated pyroptosis in neurological function recovery after cardiopulmonary resuscitation in rats

Brain injury after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) is the leading cause of neurological dysfunction and death. This study aimed to explore the mechanism of histone deacetylase 6 (HDAC6) in neurofunctional recovery following CA/CPR in rats. A rat model was established by CA/CPR treatment. Adenovirus-packaged sh-HDAC6 was injected into the tail vein. To evaluate the neurofunction of rats, survival time, neurofunctional scores, serum NSE/S100B, and brain water content were measured and Morris water maze test was performed. HDAC6, microRNA (miR)-138-5p, Nod-like receptor protein 3 (NLRP3), and pyroptotic factor levels were determined by real-time quantitative polymerase chain reaction or Western blot assay. HDAC6 and H3K9ac enrichment on miR-138-5p promoter were examined by chromatin immunoprecipitation. miR-138-5p-NLRP3 binding was analyzed by dual-luciferase reporter assay. NLRP3 inflammasome was activated with nigericin sodium salt. After CPR treatment, HDAC6 was highly expressed, while miR-138-5p was downregulated. HDAC6 downregulation improved neurofunction and reduced pyroptosis. HDAC6 enrichment on the miR-138-5p promoter deacetylated H3K9ac, inhibiting miR-138-5p, and promoting NLRP3-mediated pyroptosis. Downregulating miR-138-5p partially reversed the protective effect of HDAC6 inhibition after CPR. In Conclusion, HDAC6 enrichment on miR-138-5p promoter deacetylated H3K9ac, inhibiting miR-138-5p expression and promoting NLRP3-mediated pyroptosis, worsening neurological dysfunction in rats after CPR.

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

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

IMPORTANCE

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

Aberrant expression and regulatory role of histone deacetylase 9 in vascular endothelial cell injury in intracranial aneurysm

Intracranial aneurysm (IA) is one of the most challenging cerebrovascular lesions for clinicians. The aim of this study was to investigate the abnormal expression and role of histone deacetylase 9 (HDAC9) in IA-associated injury of vascular endothelial cells (VECs). First, IA tissue and normal arterial tissue were collected and VECs were isolated from IA patients. The expression levels of HDAC9, microRNA (miR)-34a-5p, and vascular endothelial growth factor-A (VEGFA) were determined. Cell viability, proliferation, apoptosis, and migration were assessed by Cell Counting Kit-8 (CCK-8) assay, EdU staining, TUNEL staining, and transwell assay. The binding of miR-34a-5p to VEGFA was analyzed by the dual-luciferase assay, and the accumulation of HDAC9 and lysine histone acetylation at H3 (H3K9, H3K14, and H3K18) on the miR-34a-5p promoter was detected by the chromatin immunoprecipitation assay. The results showed that HDAC9 and VEGFA were increased and miR-34a-5p was decreased in IA tissues and cells. Silencing of HDAC9 inhibited apoptosis and increased viability, proliferation, and migration of VECs, whereas overexpression of HDAC9 exerted the opposite functions. HDAC9 accumulated at the miR-34a-5p promoter to decrease miR-34a-5p expression by reducing H3 locus-specific acetylation and further promoted VEGFA expression. Knockdown of miR-34a-5p or VEGFA overexpression reversed the protective role of HDAC9 silencing in VECs injury. In conclusion, our study suggests that HDAC9 may be a therapeutic target for IA.

A Review of PARP-1 Inhibitors: Assessing Emerging Prospects and Tailoring Therapeutic Strategies

Eukaryotic organisms contain an enzyme family called poly (ADP-ribose) polymerases (PARPs), which is responsible for the poly (ADP-ribosylation) of DNA-binding proteins. PARPs are members of the cell signaling enzyme class. PARP-1, the most common isoform of the PARP family, is responsible for more than 90% of the tasks carried out by the PARP family as a whole. A superfamily consisting of 18 PARPs has been found. In order to synthesize polymers of ADP-ribose (PAR) and nicotinamide, the DNA damage nick monitor PARP-1 requires NAD+ as a substrate. The capability of PARP-1 activation to boost the transcription of proinflammatory genes, its ability to deplete cellular energy pools, which leads to cell malfunction and necrosis, and its involvement as a component in the process of DNA repair are the three consequences of PARP-1 activation that are of particular significance in the process of developing new drugs. As a result, the pharmacological reduction of PARP-1 may result in an increase in the cytotoxicity toward cancer cells.

MicroRNA-Mediated Regulation of Histone-Modifying Enzymes in Cancer: Mechanisms and Therapeutic Implications

In the past decade, significant advances in molecular research have provided a deeper understanding of the intricate regulatory mechanisms involved in carcinogenesis. MicroRNAs, short non-coding RNA sequences, exert substantial influence on gene expression by repressing translation or inducing mRNA degradation. In the context of cancer, miRNA dysregulation is prevalent and closely associated with various stages of carcinogenesis, including initiation, progression, and metastasis. One crucial aspect of the cancer phenotype is the activity of histone-modifying enzymes that govern chromatin accessibility for transcription factors, thus impacting gene expression. Recent studies have revealed that miRNAs play a significant role in modulating these histone-modifying enzymes, leading to significant implications for genes related to proliferation, differentiation, and apoptosis in cancer cells. This article provides an overview of current research on the mechanisms by which miRNAs regulate the activity of histone-modifying enzymes in the context of cancer. Both direct and indirect mechanisms through which miRNAs influence enzyme expression are discussed. Additionally, potential therapeutic implications arising from miRNA manipulation to selectively impact histone-modifying enzyme activity are presented. The insights from this analysis hold significant therapeutic promise, suggesting the utility of miRNAs as tools for the precise regulation of chromatin-related processes and gene expression. A contemporary focus on molecular regulatory mechanisms opens therapeutic pathways that can effectively influence the control of tumor cell growth and dissemination.

Epigenetic effects of short-chain fatty acids from the large intestine on host cells

Adult humans harbor at least as many microbial cells as eukaryotic ones. The largest compartment of this diverse microbial population, the gut microbiota, encompasses the collection of bacteria, archaea, viruses, and eukaryotic organisms that populate the gastrointestinal tract, and represents a complex and dynamic ecosystem that has been increasingly implicated in health and disease. The gut microbiota carries ∼100-to-150-times more genes than the human genome and is intimately involved in development, homeostasis, and disease. Of the several microbial metabolites that have been studied, short-chain fatty acids emerge as a group of molecules that shape gene expression in several types of eukaryotic cells by multiple mechanisms, which include DNA methylation changes, histone post-translational modifications, and microRNA-mediated gene silencing. Butyric acid, one of the most extensively studied short-chain fatty acids, reaches higher concentrations in the colonic lumen, where it provides a source of energy for healthy colonocytes, and its concentrations decrease towards the bottom of the colonic crypts, where stem cells reside. The lower butyric acid concentration in the colonic crypts allows undifferentiated cells, such as stem cells, to progress through the cell cycle, pointing towards the importance of the crypts in providing them with a protective niche. In cancerous colonocytes, which metabolize relatively little butyric acid and mostly rely on glycolysis, butyric acid preferentially acts as a histone deacetylase inhibitor, leading to decreased cell proliferation and increased apoptosis. A better understanding of the interface between the gut microbiota metabolites and epigenetic changes in eukaryotic cells promises to unravel in more detail processes that occur physiologically and as part of disease, help develop novel biomarkers, and identify new therapeutic modalities.

Opioids and opioid receptors; understanding pharmacological mechanisms as a key to therapeutic advances and mitigation of the misuse crisis

Opioids are a mainstay in acute pain management and produce their effects and side effects (e.g., tolerance, opioid-use disorder and immune suppression) by interaction with opioid receptors. I will discuss opioid pharmacology in some controversial areas of enquiry of anaesthetic relevance. The main opioid target is the µ (mu,MOP) receptor but other members of the opioid receptor family, δ (delta; DOP) and κ (kappa; KOP) opioid receptors also produce analgesic actions. These are naloxone-sensitive. There is important clinical development relating to the Nociceptin/Orphanin FQ (NOP) receptor, an opioid receptor that is not naloxone-sensitive. Better understanding of the drivers for opioid effects and side effects may facilitate separation of side effects and production of safer drugs. Opioids bind to the receptor orthosteric site to produce their effects and can engage monomer or homo-, heterodimer receptors. Some ligands can drive one intracellular pathway over another. This is the basis of biased agonism (or functional selectivity). Opioid actions at the orthosteric site can be modulated allosterically and positive allosteric modulators that enhance opioid action are in development. As well as targeting ligand-receptor interaction and transduction, modulating receptor expression and hence function is also tractable. There is evidence for epigenetic associations with different types of pain and also substance misuse. As long as the opioid narrative is defined by the 'opioid crisis' the drive to remove them could gather pace. This will deny use where they are effective, and access to morphine for pain relief in low income countries.

Characterisation of miRNA Expression in Dental Pulp Cells during Epigenetically-Driven Reparative Processes

Within regenerative endodontics, exciting opportunities exist for the development of next-generation targeted biomaterials that harness epigenetic machinery, including microRNAs (miRNAs), histone acetylation, and DNA methylation, which are used to control pulpitis and to stimulate repair. Although histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors (DNMTi) induce mineralisation in dental pulp cell (DPC) populations, their interaction with miRNAs during DPC mineralisation is not known. Here, small RNA sequencing and bioinformatic analysis were used to establish a miRNA expression profile for mineralising DPCs in culture. Additionally, the effects of a HDACi, suberoylanilide hydroxamic acid (SAHA), and a DNMTi, 5-aza-2'-deoxycytidine (5-AZA-CdR), on miRNA expression, as well as DPC mineralisation and proliferation, were analysed. Both inhibitors increased mineralisation. However, they reduced cell growth. Epigenetically-enhanced mineralisation was accompanied by widespread changes in miRNA expression. Bioinformatic analysis identified many differentially expressed mature miRNAs that were suggested to have roles in mineralisation and stem cell differentiation, including regulation of the Wnt and MAPK pathways. Selected candidate miRNAs were demonstrated by qRT-PCR to be differentially regulated at various time points in mineralising DPC cultures treated with SAHA or 5-AZA-CdR. These data validated the RNA sequencing analysis and highlighted an increased and dynamic interaction between miRNA and epigenetic modifiers during the DPC reparative processes.

The Functional Role and Regulatory Mechanism of FTO m6A RNA Demethylase in Human Uterine Leiomyosarcoma

Uterine leiomyosarcoma (uLMS) is the most frequent subtype of uterine sarcoma that presents a poor prognosis and high rates of recurrence and metastasis. The origin and molecular mechanism underlying and driving its clinical and biological behavior remain largely unknown. Recently, we and others have revealed the role of microRNAs, DNA methylation, and histone modifications in contributing to the pathogenesis of uLMS. However, the connection between reversible m6A RNA methylation and uLMS pathogenesis remains unclear. In this study, we assessed the role and mechanism of FTO m6A RNA demethylase in the pathogenesis of uLMS. Immunohistochemistry analysis revealed that the levels of RNA demethylases FTO and ALKBH5 were aberrantly upregulated in uLMS tissues compared to adjacent myometrium with a significant change by histochemical scoring assessment (p < 0.01). Furthermore, the inhibition of FTO demethylase with its small, potent inhibitor (Dac51) significantly decreased the uLMS proliferation dose-dependently via cell cycle arrest. Notably, RNA-seq analysis revealed that the inhibition of FTO with Dac51 exhibited a significant decrease in cell-cycle-related genes, including several CDK members, and a significant increase in the expression of CDKN1A, which correlated with a Dac51-exerted inhibitory effect on cell proliferation. Moreover, Dac51 treatment allowed the rewiring of several critical pathways, including TNFα signaling, KRAS signaling, inflammation response, G2M checkpoint, and C-Myc signaling, among others, leading to the suppression of the uLMS phenotype. Moreover, transcription factor (TF) analyses suggested that epitranscriptional alterations by Dac51 may alter the cell cycle-related gene expression via TF-driven pathways and epigenetic networks in uLMS cells. This intersection of RNA methylation and other epigenetic controls and pathways provides a framework to better understand uterine diseases, particularly uLMS pathogenesis with a dysregulation of RNA methylation machinery. Therefore, targeting the vulnerable epitranscriptome may provide an additional regulatory layer for a promising and novel strategy for treating patients with this aggressive uterine cancer.

Targeting Class I Histone Deacetylases in Human Uterine Leiomyosarcoma

Uterine leiomyosarcoma (uLMS) is the most frequent subtype of uterine sarcoma that presents a poor prognosis, high rates of recurrence, and metastasis. Currently, the molecular mechanism of the origin and development of uLMS is unknown. Class I histone deacetylases (including HDAC1, 2, 3, and 8) are one of the major classes of the HDAC family and catalyze the removal of acetyl groups from lysine residues in histones and cellular proteins. Class I HDACs exhibit distinct cellular and subcellular expression patterns and are involved in many biological processes and diseases through diverse signaling pathways. However, the link between class I HDACs and uLMS is still being determined. In this study, we assessed the expression panel of Class I HDACs in uLMS and characterized the role and mechanism of class I HDACs in the pathogenesis of uLMS. Immunohistochemistry analysis revealed that HDAC1, 2, and 3 are aberrantly upregulated in uLMS tissues compared to adjacent myometrium. Immunoblot analysis demonstrated that the expression levels of HDAC 1, 2, and 3 exhibited a graded increase from normal and benign to malignant uterine tumor cells. Furthermore, inhibition of HDACs with Class I HDACs inhibitor (Tucidinostat) decreased the uLMS proliferation in a dose-dependent manner. Notably, gene set enrichment analysis of differentially expressed genes (DEGs) revealed that inhibition of HDACs with Tucidinostat altered several critical pathways. Moreover, multiple epigenetic analyses suggested that Tucidinostat may alter the transcriptome via reprogramming the oncogenic epigenome and inducing the changes in microRNA-target interaction in uLMS cells. In the parallel study, we also determined the effect of DL-sulforaphane on the uLMS. Our study demonstrated the relevance of class I HDACs proteins in the pathogenesis of malignant uLMS. Further understanding the role and mechanism of HDACs in uLMS may provide a promising and novel strategy for treating patients with this aggressive uterine cancer.

Trehalose Attenuates Learning and Memory Impairments in Aged Rats via Overexpression of miR-181c

MicroRNAs have been recognized as important regulators of the aging process. Trehalose, a natural disaccharide, displays protective effects against neuronal impairment through several mechanisms. However, little is known about the interactive effects of aging and trehalose on behavioral function and underlying miRNA expression patterns in the hippocampus of young and old rats. Male Wistar rats were divided into four groups. Two groups of aged (24 months) and young (4 months) rats were administered 2% trehalose solution for 30 days. Two other groups of aged and young rats received regular tap water. At the end of treatment, rats were assessed for cognitive behavior using the Morris water maze test. The expression level of miR-181c and mir-34c was also measured by qRT-PCR. We found that trehalose treatment reduced learning and memory impairment in old rats compared to control old animals (p < 0.05). In contrast, cognitive performance was not significantly improved in trehalose-treated young rats in comparison with young controls (p > 0.05). We also showed that the expression level of miR-181c was significantly increased in trehalose-treated rats (p < 0.01). However, analysis of miR-34c expression level indicated no significant difference between trehalose-treated old rats and non-treated old animals (p > 0.05). Our results indicated that trehalose treatment improved learning and memory function in aged rats by targeting miR-181c. Therefore, trehalose administration may provide a therapeutic strategy to ameliorate age-associated cognitive impairment.

Elucidating miRNA Function in Cancer Biology via the Molecular Genetics' Toolbox

Micro-RNA (miRNAs) are short non-coding RNAs of about 18-20 nucleotides in length and are implicated in many cellular processes including proliferation, development, differentiation, apoptosis and cell signaling. Furthermore, it is well known that miRNA expression is frequently dysregulated in many cancers. Therefore, this review will highlight the various mechanisms by which microRNAs are dysregulated in cancer. Further highlights include the abundance of molecular genetics tools that are currently available to study miRNA function as well as their advantages and disadvantages with a special focus on various CRISPR/Cas systems This review provides general workflows and some practical considerations when studying miRNA function thus enabling researchers to make informed decisions in regards to the appropriate molecular genetics tool to be utilized for their experiments.

Parent-of-origin effects on nuclear chromatin organization and behavior in a Drosophila model for Williams-Beuren Syndrome

Prognosis of neuropsychiatric disorders in progeny requires consideration of individual (1) parent-of-origin effects (POEs) relying on (2) the nerve cell nuclear 3D chromatin architecture and (3) impact of parent-specific miRNAs. Additionally, the shaping of cognitive phenotypes in parents depends on both learning acquisition and forgetting, or memory erasure. These processes are independent and controlled by different signal cascades: the first is cAMPdependent, the second relies on actin remodeling by small GTPase Rac1 - LIMK1 (LIM-kinase 1). Simple experimental model systems such as Drosophila help probe the causes and consequences leading to human neurocognitive pathologies. Recently, we have developed a Drosophila model for Williams-Beuren Syndrome (WBS): a mutant agn^ts3 of the agnostic locus (X:11AB) harboring the dlimk1 gene. The agn^ts3 mutation drastically increases the frequency of ectopic contacts (FEC) in specific regions of intercalary heterochromatin, suppresses learning/memory and affects locomotion. As is shown in this study, the polytene X chromosome bands in reciprocal hybrids between agn^ts3 and the wild type strain Berlin are heterogeneous in modes of FEC regulation depending either on maternal or paternal gene origin. Bioinformatic analysis reveals that FEC between X:11AB and the other X chromosome bands correlates with the occurrence of short (~30 bp) identical DNA fragments partly homologous to Drosophila 372-bp satellite DNA repeat. Although learning acquisition in a conditioned courtship suppression paradigm is similar in hybrids, the middle-term memory formation shows patroclinic inheritance. Seemingly, this depends on changes in miR-974 expression. Several parameters of locomotion demonstrate heterosis. Our data indicate that the agn^ts3 locus is capable of trans-regulating gene activity via POEs on the chromatin nuclear organization, thereby affecting behavior.

Chromatin Structure and "DNA Sequence View": The Role of Satellite DNA in Ectopic Pairing of the Drosophila X Polytene Chromosome

Chromatin 3D structure plays a crucial role in regulation of gene activity. Previous studies have envisioned spatial contact formations between chromatin domains with different epigenetic properties, protein compositions and transcription activity. This leaves specific DNA sequences that affect chromosome interactions. The Drosophila melanogaster polytene chromosomes are involved in non-allelic ectopic pairing. The mutant strain agnts3, a Drosophila model for Williams-Beuren syndrome, has an increased frequency of ectopic contacts (FEC) compared to the wild-type strain Canton-S (CS). Ectopic pairing can be mediated by some specific DNA sequences. In this study, using our Homology Segment Analysis software, we estimated the correlation between FEC and frequency of short matching DNA fragments (FMF) for all sections of the X chromosome of Drosophila CS and agnts3 strains. With fragment lengths of 50 nucleotides (nt), CS showed a specific FEC-FMF correlation for 20% of the sections involved in ectopic contacts. The correlation was unspecific in agnts3, which may indicate the alternative epigenetic mechanisms affecting FEC in the mutant strain. Most of the fragments that specifically contributed to FMF were related to 1.688 or 372-bp middle repeats. Thus, middle repetitive DNA may serve as an organizer of ectopic pairing.

HDAC Screening Identifies the HDAC Class I Inhibitor Romidepsin as a Promising Epigenetic Drug for Biliary Tract Cancer

Simple Summary

Biliary tract cancer (BTC) is a rare disease with dismal outcomes. Therefore, the investigation of new therapeutic targets is urgently required. In this study, we demonstrate that histone deacetylases (HDACs) are expressed in BTC cell lines and that treatment of BTC cells with different HDAC class inhibitors reduces cell viability. Specifically, we found that BTC cells are vulnerable to the HDAC class I inhibitor romidepsin. Treatment with romidepsin resulted in apoptotic cell death of BTC cells and reduced HDAC activity. Furthermore, romidepsin augmented the cytotoxic effect of the standard chemotherapeutic cisplatin. HDAC class I proteins were also expressed in BTC patient samples. We detected that BTC patients with high HDAC-2-expressing tumors showed a significantly shorter survival. In summary, we were able to demonstrate that BTC cells are vulnerable to HDAC inhibition and that the HDAC class I inhibitor romidepsin might be a promising anti-BTC substance.

Abstract

Inhibition of histone deacetylases (HDACs) is a promising anti-cancer approach. For biliary tract cancer (BTC), only limited therapeutic options are currently available. Therefore, we performed a comprehensive investigation of HDAC expression and pharmacological HDAC inhibition into a panel of eight established BTC cell lines. The screening results indicate a heterogeneous expression of HDACs across the studied cell lines. We next tested the effect of six established HDAC inhibitors (HDACi) covering pan- and class-specific HDACis on cell viability of BTC cells and found that the effect (i) is dose- and cell-line-dependent, (ii) does not correlate with HDAC isoform expression, and (iii) is most pronounced for romidepsin (a class I HDACi), showing the highest reduction in cell viability with IC₅₀ values in the low-nM range. Further analyses demonstrated that romidepsin induces apoptosis in BTC cells, reduces HDAC activity, and increases acetylation of histone 3 lysine 9 (H3K9Ac). Similar to BTC cell lines, HDAC 1/2 proteins were heterogeneously expressed in a cohort of resected BTC specimens (n = 78), and their expression increased with tumor grading. The survival of BTC patients with high HDAC-2-expressing tumors was significantly shorter. In conclusion, HDAC class I inhibition in BTC cells by romidepsin is highly effective in vitro and encourages further in vivo evaluation in BTC. In situ assessment of HDAC 2 expression in BTC specimens indicates its importance for oncogenesis and/or progression of BTC as well as for the prognosis of BTC patients.

An Assessment on Ethanol-Blended Gasoline/Diesel Fuels on Cancer Risk and Mortality

Although cancer is traditionally considered a genetic disease, the epigenetic abnormalities, including DNA hypermethylation, histone deacetylation, and/or microRNA dysregulation, have been demonstrated as a hallmark of cancer. Compared with gene mutations, aberrant epigenetic changes occur more frequently, and cellular epigenome is more susceptible to change by environmental factors. Excess cancer risks are positively associated with exposure to occupational and environmental chemical carcinogens, including those from gasoline combustion exhausted in vehicles. Of note, previous studies proposed particulate matter index (PMI) as a measure for gasoline sooting tendency, and showed that, compared with the other molecules in gasoline, 1,2,4-Trimethylbenzene, 2-methylnaphthalene and toluene significantly contribute to PMI of the gasoline blends. Mechanistically, both epigenome and genome are important in carcinogenicity, and the genotoxicity of chemical agents has been thoroughly studied. However, less effort has been put into studying the epigenotoxicity. Moreover, as the blending of ethanol into gasoline substitutes for carcinogens, like benzene, toluene, xylene, butadiene, and polycyclic aromatic hydrocarbons, etc., a reduction of secondary aromatics has been achieved in the atmosphere. This may lead to diminished cancer initiation and progression through altered cellular epigenetic landscape. The present review summarizes the most important findings in the literature on the association between exposures to carcinogens from gasoline combustion, cancer epigenetics and the potential epigenetic impacts of biofuels.

Repurposing Belinostat for Alleviation of Atopic Dermatitis

Atopic dermatitis (AD) is a highly prevalent chronic inflammatory skin disease that is characterized by intense pruritus, seriously affecting patients' quality of life. Its pathophysiology, which involves both the adaptive and innate immune responses as well as skin barrier defects, is still poorly understood. We recently identified a microRNA, miR-335, as a key driver of keratinocyte differentiation and cornification, which is essential for the establishment of a healthy skin barrier. However, expression of miR-335 is lost in AD, leading to barrier defect. We further demonstrated how belinostat, a histone deacetylase inhibitor, can effectively restore miR-335 and resolve the barrier defect in a dry skin model. Here, in this commentary, we highlight the role of belinostat in the treatment of AD and discuss the need for more research into crosstalk between epigenetic and non-coding RNA-based regulation, as well as possible therapeutic strategies targeting the epigenome.

GeromiRs Are Downregulated in the Tumor Microenvironment during Colon Cancer Colonization of the Liver in a Murine Metastasis Model

Cancer is a phenomenon broadly related to ageing in various ways such as cell cycle deregulation, metabolic defects or telomerases dysfunction as principal processes. Although the tumor cell is the main actor in cancer progression, it is not the only element of the disease. Cells and the matrix surrounding the tumor, called the tumor microenvironment (TME), play key roles in cancer progression. Phenotypic changes of the TME are indispensable for disease progression and a few of these transformations are produced by epigenetic changes including miRNA dysregulation. In this study, we found that a specific group of miRNAs in the liver TME produced by colon cancer called geromiRs, which are miRNAs related to the ageing process, are significantly downregulated. The three principal cell types involved in the liver TME, namely, liver sinusoidal endothelial cells, hepatic stellate (Ito) cells and Kupffer cells, were isolated from a murine hepatic metastasis model, and the miRNA and gene expression profiles were studied. From the 115 geromiRs and their associated hallmarks of aging, which we compiled from the literature, 75 were represented in the used microarrays, 26 out of them were downregulated in the TME cells during colon cancer colonization of the liver, and none of them were upregulated. The histone modification hallmark of the downregulated geromiRs is significantly enriched with the geromiRs miR-15a, miR-16, miR-26a, miR-29a, miR-29b and miR-29c. We built a network of all of the geromiRs downregulated in the TME cells and their gene targets from the MirTarBase database, and we analyzed the expression of these geromiR gene targets in the TME. We found that Cercam and Spsb4, identified as prognostic markers in a few cancer types, are associated with downregulated geromiRs and are upregulated in the TME cells.

Noncoding RNAs and Intracerebral Hemorrhage

BACKGROUND & OBJECTIVE

Intracerebral hemorrhage (ICH) is the most devastating subtype of stroke, for which there are few effective interventions. Computed tomography is accepted as the gold standard for diagnosis, whereas surgical evacuation is the main treatment for ICH. However, in emergency rooms, time is limited and information regarding a patient's clinical status or tolerance is typically not available. Many studies over the last decade have investigated the fundamental mechanisms of ICH and especially hematoma, which not only cause physical damage but also release toxins that have detrimental effects. However, there remain many gaps in our understanding of ICH. Compared to ischemic stroke, there is little known about the ICH pathogenesis and treatment options, and few specific biomarkers are available for monitoring disease progression, which include hematoma enlargement and perihematoma edema. Noncoding RNAs (ncRNAs) are involved in various biological processes and are potential biomarkers and therapeutic tools in central nervous system diseases. Recent studies have examined the role of ncRNAs including microRNAs, long noncoding RNAs, and circular RNAs-the three main subgroups associated with stroke-in ICH models. A deeper understanding of the functions of ncRNAs in different biological processes can provide a basis for developing more effective therapeutic strategies to prevent neuronal damage following ICH. In clinical settings, ncRNAs can serve as biomarkers for predicting the degree of injury resulting from ICH.

CONCLUSION

In this review, we discuss the current state of knowledge of the role of ncRNAs in ICH.

The expression of microRNA 146a in patients with ischemic stroke: an observational study

Aim

We conducted the present prospective study to assess the level of microRNA (miRNA) 146a in patients with ischemic stroke and its correlation with patients' characteristics.

Methods

We conducted an observational study that included adult patients (≥18 years old) who presented within 24 hrs after the onset of the symptoms of acute ischemic stroke. In addition, age- and sex-matched healthy volunteers were included as control group. The primary outcome in the present study was the difference in miRNA 146a expression between patients with ischemic stroke and control group participants. The expression of miRNA 146a was measured using quantitative real-time PCR. Quantitative real-time PCR amplification and analysis were performed using Rotor-Gene Q thermal cycler.

Results

The present study included 44 patients with ischemic stroke and 22 matched controls. Regarding the primary outcome of the present study, the median expression of miRNA 146a in patients with ischemic stroke was -1.98 fold (IQR -27.1-3.9) compared to 1.75 fold (IQR -2.25-5.27) in control group (P<0.001). However, the subgroup analysis showed that the expression of miRNA 146a was significantly downregulated in comatosed patients only (P<0.001). The expression of miRNA 146a correlated negatively with Glasgow Coma Scale score in comatose patients (r=-0.352, P=0.022).

Conclusion

In conclusion, the expression of miRNA 146a is significantly downregulated in ischemic stroke patients. Further studies are needed to assess its diagnostic utility and therapeutic potentials.

The Roles of MicroRNAs in Stroke: Possible Therapeutic Targets

Stroke is one of the most devastating diseases worldwide. In recent years, a great number of studies have focused on the effects of microRNAs (miRNAs) on stroke and the results demonstrated that the expressions of miRNAs are associated with the prognosis of stroke. In the present study, we review relevant articles regarding miRNAs and stroke and will explain the complex link between both. The miRNAs participate extensively in the pathophysiology following the stroke, including apoptosis, neuroinflammation, oxidative stress, blood–brain barrier (BBB) disruption and brain edema. The information about the stroke–miRNA system may be helpful for therapeutic and diagnostic methods in stroke treatment.

MicroRNA-214-3p inhibits proliferation and cell cycle progression by targeting MELK in hepatocellular carcinoma and correlates cancer prognosis

Background

MicroRNAs are considered as potential regulators in various biological pathways and contribute to the diagnosis and prognosis of cancers. MicroRNA-214-3p (miR-214-3p) was proved to be correlated with various cancers in recent studies. However, the biological functions of miR-214-3p in hepatocellular carcinoma (HCC) and its association with the prognosis of HCC after liver transplantation are still unevaluated. Here we intended to elucidate the functional implication of miR-214-3p in regulation of cell proliferation and apoptosis and its potential prediction of clinical prognosis of HCC patients.

Methods

Expressions of miR-214-3p in 98 HCC patients and three HCC cell lines were detected by quantitative reverse transcription PCR (qRT-PCR) to explore the association of miR-214-3p expression and clinicopathological characteristics. The effects of miR-214-3p on cell proliferation and apoptosis were examined by proliferation and flow cytometry assay, respectively. The direct target gene of miR-214-3p was also detected by luciferase reporter assay.

Results

The effects of miR-214-3p on cell proliferation and apoptosis were examined by proliferation and flow cytometry assay, respectively. The direct target gene of miR-214-3p was also detected by luciferase reporter assay. The results showed that miR-214-3p expression was downregulated in primary HCC samples compared with normal liver tissues, and was decreased in HCC recurrence species compared with non-recurrence controls (P = 0.001). Low miR-214-3p level was associated with poor overall survival (OS) (Log rank P = 0.003) and recurrence-free survival (RFS) (Log rank P = 0.007). Moreover, miR-214-3p precursor transfection resulted in decreased cell proliferation, cell cycle arrest at G1 phase, and enhanced cell apoptosis in HepG2 and HUH-7 cells. Further investigation showed that miR-214-3p could regulate its target gene maternal embryonic leucine zipper kinase (MELK) by directly binding to MELK-3′-UTR.

Conclusions

miR-214-3p suppresses HCC progression by directly down-regulating MELK expression, indicating a potential therapeutic target for the treatment and prognosis of HCC patients.

Emerging Roles of microRNAs in Ischemic Stroke: As Possible Therapeutic Agents

Stroke is one of the leading causes of death and physical disability worldwide. The consequences of stroke injuries are profound and persistent, causing in considerable burden to both the individual patient and society. Current treatments for ischemic stroke injuries have proved inadequate, partly owing to an incomplete understanding of the cellular and molecular changes that occur following ischemic stroke. MicroRNAs (miRNA) are endogenously expressed RNA molecules that function to inhibit mRNA translation and have key roles in the pathophysiological processes contributing to ischemic stroke injuries. Potential therapeutic areas to compensate these pathogenic processes include promoting angiogenesis, neurogenesis and neuroprotection. Several miRNAs, and their target genes, are recognized to be involved in these recoveries and repair mechanisms. The capacity of miRNAs to simultaneously regulate several target genes underlies their unique importance in ischemic stroke therapeutics. In this Review, we focus on the role of miRNAs as potential diagnostic and prognostic biomarkers, as well as promising therapeutic agents in cerebral ischemic stroke.

Epigenetics in Stroke Recovery

Abstract: While the death rate from stroke has continually decreased due to interventions in the hyperacute stage of the disease, long-term disability and institutionalization have become common sequelae in the aftermath of stroke. Therefore, identification of new molecular pathways that could be targeted to improve neurological recovery among survivors of stroke is crucial. Epigenetic mechanisms such as post-translational modifications of histone proteins and microRNAs have recently emerged as key regulators of the enhanced plasticity observed during repair processes after stroke. In this review, we highlight the recent advancements in the evolving field of epigenetics in stroke recovery.

Involvement of upregulation of miR-210 in a rat epilepsy model

Epilepsy is a common type of neurological disorder with complex etiology. The mechanisms are still not clear. MicroRNAs are endogenous noncoding RNAs with many physiological activities. Multiple microRNAs were abnormally expressed in status epilepticus, including miR-210. In this study, we applied lithium chloride and pilocarpine to induce epileptic activity and aimed to disclose the potential mechanisms. Our data showed that miR-210 was significantly upregulated in hippocampus one day after modeling (P<0.05 vs control) and the high expression of miR-210 lasted for at least 30 days. By contrast, γ-aminobutyric acid (GABA) level significantly decreased concurrently after modeling (P<0.05 vs control). To question whether miR-210 could be a potential therapeutic target for epilepsy, miR-210 inhibitor was administrated through intrahippocampal injection after epilepsy modeling. Our data showed that morphological changes of hippocampal neurons and apoptosis triggered by epilepsy were mitigated by miR-210 inhibition. More importantly, the expressions of GABA-related proteins, including GABAA receptor α1, glutamate decarboxylase, and GABA transporter 1, were significantly elevated after epilepsy modeling in both mRNA and protein levels 3 days postmodeling (P<0.05 vs control), which were mitigated by miR-210 inhibitor treatment (P<0.05 vs model). In addition, epilepsy-induced upregulation of GABA transaminase was alleviated by miR-210 inhibitor. Taken together, these data implicated potential roles of miR-210 in lithium chloride-pilocarpine-induced epilepsy model and miR-210 could serve as a potential therapeutic target in status epilepticus.

Scriptaid Treatment Decreases DNA Methyltransferase 1 Expression by Induction of MicroRNA-152 Expression in Porcine Somatic Cell Nuclear Transfer Embryos

Abnormal epigenetic reprogramming of donor nuclei after somatic cell nuclear transfer (SCNT) is thought to be the main cause of low cloning efficiencies. A growing body of evidence has demonstrated a positive role of Scriptaid, a histone deacetylase inhibitor (HDACi) that belongs to an existing class of hydroxamic acid-containing HDACis, on the development competence of cloned embryos in many species. The present study investigated the effects of Scriptaid on the development of porcine SCNT embryos in vitro and its mechanism. Treatment with 300 or 500 nM Scriptaid for 20 h after activation significantly increased the percentage of SCNT embryos that developed to the blastocyst stage and the total number of cells per blastocyst and significantly decreased the percentage of apoptotic cells in blastocysts. Scriptaid treatment significantly increased the level of histone H3 acetylated at K9 and the conversion of 5-methylcytosine into 5-hydroxymethylcytosine and significantly decreased the level of histone H3 trimethylated at K9 at the pronuclear stage. As a potential mechanism for the DNA methylation changes, our results showed that the expression of DNA methyltransferase 1 was frequently down-regulated in Scriptaid-treated embryos in comparison with untreated embryos and was inversely correlated to endogenous microRNA-152 (miR-152). Taken together, these findings illustrated a crucial functional crosstalk between miR-152 and DNMT1. Meanwhile, mRNA and protein levels of POU5F1 and CDX2 were increased in Scriptaid-treated embryos. mRNA levels of Caspase3, and Bax were significantly decreased and that of Bcl-xL was significantly increased in Scriptaid-treated embryos. In conclusion, these observations would contribute to uncover the nuclear reprogramming mechanisms underlying the effects of Scriptaid on the improvement of porcine SCNT embryos.