Regulatory Role of MicroRNAs in Brain Development and Function

Stress-Related Roles of Exosomes and Exosomal miRNAs in Common Neuropsychiatric Disorders

Exosomes, natural nanovesicles that contain a cargo of biologically active molecules such as lipids, proteins, and nucleic acids, are released from cells to the extracellular environment. They then act as autocrine, paracrine, or endocrine mediators of communication between cells by delivering their cargo into recipient cells and causing downstream effects. Exosomes are greatly enriched in miRNAs, which are small non-coding RNAs that act both as cytoplasmic post-transcriptional repression agents, modulating the translation of mRNAs into proteins, as well as nuclear transcriptional gene activators. Neuronal exosomal miRNAs have important physiologic functions in the central nervous system (CNS), including cell-to-cell communication, synaptic plasticity, and neurogenesis, as well as modulating stress and inflammatory responses. Stress-induced changes in exosomal functions include effects on neurogenesis and neuroinflammation, which can lead to the appearance of various neuropsychiatric disorders such as schizophrenia, major depression, bipolar disorder, and Alzheimer's and Huntington's diseases. The current knowledge regarding the roles of exosomes in the pathophysiology of common mental disorders is discussed in this review.

Identification of Stage-Specific microRNAs that Govern the Early Stages of Sequential Oral Oncogenesis by Strategically Bridging Human Genetics with Epigenetics and Utilizing an Animal Model

Oral squamous cell carcinoma (OSCC) is a highly prevalent and aggressive malignancy, with mortality rates reaching 60%, mainly due to its excessive diagnostic delay. MiRNAs, a class of crucial epigenetic gene-expression regulators, have emerged as potential diagnostic biomarkers, with >200 molecules exhibiting expressional dysregulation in OSCC. We had previously established an in silico methodology for the identification of the most disease-specific molecules by bridging genetics and epigenetics. Here, we identified the stage-specific miRNAs that govern the asymptomatic early stages of oral tumorigenesis by exploiting seed-matching and the reverse interplay between miRNA levels and their target genes' expression. Incorporating gene-expression data from our group's experimental hamster model of sequential oral oncogenesis, we bioinformatically detected the miRNAs that simultaneously target/regulate >75% of the genes that are characteristically upregulated or downregulated in the consecutive stages of hyperplasia, dysplasia, and early invasion, while exhibiting the opposite expressional dysregulation in OSCC-derived tissue and/or saliva specimens. We found that all stages share the downregulation of miR-34a-5p, miR124-3p, and miR-125b-5p, while miR-1-3p is under-expressed in dysplasia and early invasion. The malignant early-invasion stage is distinguished by the downregulation of miR-147a and the overexpression of miR-155-5p, miR-423-3p, and miR-34a-5p. The identification of stage-specific miRNAs may facilitate their utilization as biomarkers for presymptomatic OSCC diagnosis.

Unleashing the Neurotherapeutic Potential: The Crucial Role of miR-206-3p in Facilitating Hsp90aa1-Mediated Central Nervous System Injuries During Heat Stroke

This study aims to explore the molecular mechanisms of miR-206-3p in regulating Hsp90aa1 and its involvement in the central nervous system (CNS) injury in heat stroke. Weighted gene co-expression network analysis (WGCNA) was performed on the GSE64778 dataset of heat stroke to identify module genes most closely associated with disease characteristics. Through the selection of key genes and predicting upstream miRNAs using RNAInter and miRWalk databases, the regulatory relationship between miR-206-3p and Hsp90aa1 was determined. Through in vitro experiments, various methods, including bioinformatics analysis, dual-luciferase reporter gene assay, RIP experiment, and RNA pull-down experiment, were utilized to validate this regulatory relationship. Furthermore, functional experiments, including CCK-8 assay to test neuron cell viability and flow cytometry to assess neuron apoptosis levels, confirmed the role of miR-206-3p. Transmission electron microscopy, real-time quantitative PCR, DCFH-DA staining, and ATP assay were employed to verify neuronal mitochondrial damage. Heat stroke rat models were constructed, and mNSS scoring and cresyl violet staining were utilized to assess neural functional impairment. Biochemical experiments were conducted to evaluate inflammation, brain water content, and histopathological changes in brain tissue using H&E staining. TUNEL staining was applied to detect neuronal apoptosis in brain tissue. RT-qPCR and Western blot were performed to measure gene and protein expression levels, further validating the regulatory relationship in vivo. Bioinformatics analysis indicated that miR-206-3p regulation of Hsp90aa1 may be involved in CNS injury in heat stroke. In vivo, animal experiments demonstrated that miR-206-3p and Hsp90aa1 co-localized in neurons of the rat hippocampal CA3 region, and with prolonged heat stress, the expression of miR-206-3p gradually increased while the expression of Hsp90aa1 gradually decreased. Further in vitro cellular mechanism validation and functional experiments confirmed that miR-206-3p could inhibit neuronal cell viability and promote apoptosis and mitochondrial damage by targeting Hsp90aa1. In vivo, experiments confirmed that miR-206-3p promotes CNS injury in heat stroke. This study revealed the regulatory relationship between miR-206-3p and Hsp90aa1, suggesting that miR-206-3p could regulate the expression of Hsp90aa1, inhibit neuronal cell viability, and promote apoptosis, thereby contributing to CNS injury in heat stroke.

Constraint therapy promotes motor cortex remodeling and functional improvement by regulating c-Jun/miR-182-5p/Nogo - A signals in hemiplegic cerebral palsy mice

BACKGROUND

Our previous study has confirmed that constraint-induced movement therapy (CIMT) could promote neural remodeling in hemiplegic cerebral palsy (HCP) mice through Nogo-A/NgR/RhoA/ROCK signaling, however, the upstream mechanism was still unclear. Therefore, the present study aimed to further explore the mechanism of CIMT regulating the expression of Nogo-A in HCP mice.

METHOD

HCP mice were well established through ligating the left common carotid artery of 7-day-old pups and being placed in a hypoxic box which was filled with a mixture of 8% oxygen and 92% nitrogen. CIMT intervention was conducted by taping to fix the entire arm of the contralateral side (left) to force the mice to use the affected limb (right). Bioinformatics prediction and luciferase experiment were performed to confirm that miR-182-5p was targeted with Nogo-A. The beam test and grip test were applied to examine the behavioral performance under the intervention of c-Jun and CIMT. Also, immunofluorescence, Golgi staining, and transmission electron microscopy were conducted to show that the lenti-expression of c-Jun could increases the expression of myelin, and downregulates the expression of Nogo-A under the CIMT on HCP mice.

RESULT

(1) The beam walking test and grip test experiment results showed that compared with the control group, the HCP + nCIMT group's forelimb grasping ability and balance coordination ability were decreased (P < 0.05). (2) The results of Golgi staining, and transmission electron microscopy showed that the thickness of myelin sheath and the density of dendritic spines in the HCP + nCIMT group were lower than those in the control group (P < 0.05). Compared with the HCP + nCIMT group, the cerebral cortex myelin sheath thickness, dendrite spine density and nerve filament expression were increased in HCP + CIMT group (P < 0.05). (3) Immunofluorescence staining showed that the expression of Nogo-A in the cerebral cortex of the HCP + nCIMT group was higher than that of the HCP + CIMT group (P < 0.05). Compared with the HCP + CIMT group, the expression of Nogo-A in the HCP + LC + CIMT group was decreased and, in the HCP, + SC + CIMT group was significantly increased (P < 0.05). Compared with the HCP + nCIMT group, the expression of c-Jun in the control, HCP + CIMT, HCP + LC + nCIMT and HCP + LC + CIMT groups was significantly increased, and in the HCP + SC + CIMT was decreased (P < 0.05). (4) Real-time quantitative polymerase chain reaction (RT-qPCR) results showed that the expression level of miR-182-5p in the HCP + LC + CIMT group was more increased than that in the HCP + nCIMT group (P < 0.05). The expression level of miR-182-5p in the HCP + LC + CIMT group was higher than that in the HCP + LC + nCIMT group and the HCP + SC + CIMT group (P < 0.05).

CONCLUSION

These data identified that CIMT might stimulate the remodeling of neurons and myelin in the motor cortex by partially inhibiting the c-Jun/miR-182-5p/Nogo-A pathway, thereby facilitating the grasping performance and balance function of HCP mice.

Review of Disease-Specific microRNAs by Strategically Bridging Genetics and Epigenetics in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most prevalent human malignancies and a global health concern with a poor prognosis despite some therapeutic advances, highlighting the need for a better understanding of its molecular etiology. The genomic landscape of OSCC is well-established and recent research has focused on miRNAs, which regulate gene expression and may be useful non-invasive biomarkers or therapeutic targets. A plethora of findings regarding miRNA expression have been generated, posing challenges for the interpretation and identification of disease-specific molecules. Hence, we opted to identify the most important regulatory miRNAs by bridging genetics and epigenetics, focusing on the key genes implicated in OSCC development. Based on published reports, we have developed custom panels of fifteen major oncogenes and five major tumor suppressor genes. Following a miRNA/target gene interaction analysis and a comprehensive study of the literature, we selected the miRNA molecules which target the majority of these panels that have been reported to be downregulated or upregulated in OSCC, respectively. As a result, miR-34a-5p, miR-155-5p, miR-124-3p, miR-1-3p, and miR-16-5p appeared to be the most OSCC-specific. Their expression patterns, verified targets, and the signaling pathways affected by their dysregulation in OSCC are thoroughly discussed.

Arsenic resistance protein 2 and microRNA biogenesis: Biological implications in cancer development

Arsenic resistance protein 2 (Ars2) is a nuclear protein that plays a critical role in the regulation of microRNA (miRNA) biogenesis. Ars2 is required for cell proliferation and for the early stages of mammalian development through a possible effect on miRNA processing. Increasing evidence reveal that Ars2 is highly expressed in proliferating cancer cells, suggesting that Ars2 may be a potential therapeutic target for cancer. Therefore, development of the novel Ars2 inhibitors could represent the novel therapeutic strategies for treatment of cancer. In this review, we briefly discuss the mechanisms by which Ars2 regulates miRNA biogenesis and its impact on cell proliferation and cancer development. Particularly, we mainly discuss the role of Ars2 in the regulation of cancer development and highlight pharmacological targeting of Ars2 as a promising cancer therapeutic strategy.

Epigenetic regulation and T-cell responses in endometriosis – something other than autoimmunity

Endometriosis is defined as the presence of endometrial-like glands and stroma located outside the uterine cavity. This common, estrogen dependent, inflammatory condition affects up to 15% of reproductive-aged women and is a well-recognized cause of chronic pelvic pain and infertility. Despite the still unknown etiology of endometriosis, much evidence suggests the participation of epigenetic mechanisms in the disease etiopathogenesis. The main rationale is based on the fact that heritable phenotype changes that do not involve alterations in the DNA sequence are common triggers for hormonal, immunological, and inflammatory disorders, which play a key role in the formation of endometriotic foci. Epigenetic mechanisms regulating T-cell responses, including DNA methylation and posttranslational histone modifications, deserve attention because tissue-resident T lymphocytes work in concert with organ structural cells to generate appropriate immune responses and are functionally shaped by organ-specific environmental conditions. Thus, a failure to precisely regulate immune cell transcription may result in compromised immunological integrity of the organ with an increased risk of inflammatory disorders. The coexistence of endometriosis and autoimmunity is a well-known occurrence. Recent research results indicate regulatory T-cell (Treg) alterations in endometriosis, and an increased number of highly active Tregs and macrophages have been found in peritoneal fluid from women with endometriosis. Elimination of the regulatory function of T cells and an imbalance between T helper cells of the Th1 and Th2 types have been reported in the endometria of women with endometriosis-associated infertility. This review aims to present the state of the art in recognition epigenetic reprogramming of T cells as the key factor in the pathophysiology of endometriosis in the context of T-cell-related autoimmunity. The new potential therapeutic approaches based on epigenetic modulation and/or adoptive transfer of T cells will also be outlined.

Exosomes and exosomal non‑coding RNAs throughout human gestation (Review)

In recent years, research on exosomes and their content has been intensive, which has revealed their important role in cell-to-cell communication, and has implicated exosomal biomolecules in a broad spectrum of physiological processes, as well as in the pathogenesis of various diseases. Pregnancy and its normal progression rely highly on the efficient communication between the mother and the fetus, mainly mediated by the placenta. Recent studies have established the placenta as an important source of circulating exosomes and have demonstrated that exosome release into the maternal circulation gradually increases during pregnancy, starting from six weeks of gestation. This orchestrates maternal-fetal crosstalk, including maternal immune tolerance and pregnancy-associated metabolic adaptations. Furthermore, an increased number of secreted exosomes, along with altered patterns of exosomal non-coding RNAs (ncRNAs), especially microRNAs and long non-coding RNAs (lncRNAs), have been observed in a number of pregnancy complications, such as gestational diabetes mellitus and preeclampsia. The early detection of exosomes and specific exosomal ncRNAs in various biological fluids during pregnancy highlights them as promising candidate biomarkers for the diagnosis, prognosis and treatment of numerous pregnancy disorders in adolescents and adults. The present review aimed to provide insight into the current knowledge regarding the potential, only partially elucidated, role of exosomes and exosomal cargo in the regulation and progression of normal pregnancy, as well as their potential dysregulation and contribution to pathological pregnancy situations.

Exposure to nanographene oxide induces gene expression dysregulation in normal human astrocytes

Objective. Nanographene oxide, an oxidation derivative of graphene, is considered to be one of the nanomaterials attractive for biomedical applications, although this nanomaterial is toxic. The increasing exploitation of graphene-based materials necessitates a comprehensive evaluation of the potential impact of these materials on the human health. Moreover, it is necessary to investigate in detail the mechanisms of its toxic effect on living cells particularly at the genome level. The present study aimed to evaluate the impact of low doses of nanographene oxide on the expression of key regulatory genes in normal human astrocytes.

Methods. Normal human astrocytes, line NHA/TS, were exposed to low doses of nanographene oxide (1 and 4 ng/ml) for 24 h. RNA was extracted from the cells and used for cDNA synthesis. The expression levels of NAMPT, TSPAN13, BCAR3, BRCA1, PTGS2, P4HA1, and P4HA2 mRNAs as well as microRNAs were measured by quantitative polymerase chain reaction.

Results. It was found that the low doses of nanographene oxide induced a dysregulation in the expression of the key regulatory genes in normal human astrocytes in dose-dependent (1 and 4 ng/ml) and gene-specific manner. Nanographene oxide also strongly suppressed the expression of NAMPT, BCAR3, and TSPAN13 genes and significantly up-regulated BRCA1, PTGS2, P4HA1, and P4HA2 ones with a more significant effect in P4HA1 and P4HA2 genes. The expression of miR-96-5p and miR-145-5p was also down-regulated in astrocytes treated with nanographene oxide in a dose-dependent manner.

Conclusion. The data obtained demonstrate that the low doses of nanographene oxide disturbed the genome functions by changing the expression levels of key regulatory genes in gene-specific and dose-dependent manner. Moreover, a higher dose of nanographene oxide induced more pronounced changes in expression of genes indicating for both genotoxic and neurotoxic possible effects in the normal human astrocytes.

The impact of single walled carbon nanotubes on the expression of microRNA in zebrafish (Danio rerio) embryos

Objective. Single-walled carbon nanotubes (SWCNTs) are able to cross the blood-brain barrier, penetrate through the cell membrane, and accumulate in the cell nucleus, which purposefully allows their use in the health sciences as imaging probes and drug carriers in the cancer therapy. The aim of this study was to investigate the effect of low doses of SWCNTs on the expression of microRNAs associated with the cell proliferation and the brain development in zebrafish (Danio rerio) embryos. Methods. The zebrafish embryos (72 h post fertilization) were exposed to low doses of SWCNTs (2 and 8 ng/ml of medium) for 24 or 72 h. The microRNAs (miR-19, miR-21, miR-96, miR-143, miR-145, miR-182, and miR-206) expression levels were measured by quantitative polymerase chain reaction analysis. Results. It was found that low doses of SWCNTs elicited dysregulation in the expression of numerous cell proliferation and brain development-related microRNAs (miR-19, miR-21, miR-96, miR-143, miR-145, miR-182, and miR-206) in dose- (2 and 8 ng/ml of medium) as well as malformations in the zebrafish embryos brain development in a time-dependent (24 and 72 h) manner. Conclusion. Taken together, the present data indicate that the low doses of SWCNTs disturbed the genome functions and reduced the miR-19, miR-21, miR-96, miR-143, miR-145, miR-182, and miR-206 expression levels in dose- and time-dependent manners and interrupted the brain development in the zebrafish embryos indicating for both the genotoxic and the neurotoxic interventions.

MicroRNA-193b-3p reduces oxidative stress and mitochondrial damage in rats with cerebral ischemia-reperfusion injury via the seven in absentia homolog 1/Jun N-terminal kinase pathway

Ischemic stroke is one of the major causes of death and disability among adults. This study sought to explore the mechanism of microRNA (miR)-193b-3p in rats with cerebral ischemia-reperfusion (I/R) injury. The cerebral I/R injury models of rats were established using the suture-occluded method. The pathological changes were observed, and oxidative stress (OS) and mitochondrial function indexes in rat brain tissue were examined. The levels of miR-193b-3p and seven in absentia homolog 1 (SIAH1) were detected. miR-193b-3p agomir or antagomir was injected into the lateral ventricle of I/R rats to overexpress or inhibit miR-193b-3p expression. The targeting relationship between miR-193b-3p and SIAH1 was verified. The effect of SIAH1 overexpression on brain injury in I/R rats was investigated by injecting the lentivirus vector into the lateral ventricle. The phosphorylation level of Jun N-terminal kinase (JNK) was identified. miR-193b-3p was lowly expressed in I/R rats. Overexpression of miR-193b-3p alleviated the pathological damage of I/R rats and limited the OS and mitochondrial damage. miR-193b-3p targeted SIAH1. Overexpression of SIAH1 partially reversed the protection of miR-193b-3p overexpression against cerebral I/R injury. p-JNK was up-regulated in I/R rats and overexpression of miR-193b-3p inhibited p-JNK. Overall, overexpression of miR-193b-3p targeted SIAH1 to inhibit the activation of the JNK pathway and protect rats against cerebral I/R injury.

Hippocampal miR-206-3p participates in the pathogenesis of depression via regulating the expression of BDNF

As a widely-known neuropsychiatric disorder, the exact pathogenesis of depression remains elusive. MiRNA-206 (miR-206) is conventionally known as one of the myomiRs and has two forms: miR-206-3p and miR-206-5p. Recently, miR-206 has been demonstrated to regulate the biosynthesis of brain-derived neurotrophic factor (BDNF), a very popular target involved in depression and antidepressant responses. Here we assumed that miR-206 may play a role in depression, and various methods including the chronic social defeat stress (CSDS) model of depression, quantitative real-time reverse transcription PCR, western blotting, immuofluorescence and virus-mediated gene transfer were used together. It was found that CSDS robustly increased the level of miR-206-3p but not miR-206-5p in the hippocampus. Both genetic overexpression of hippocampal miR-206-3p and intranasal administration of AgomiR-206-3p induced not only notable depressive-like behaviors but also significantly decreased hippocampal BDNF signaling cascade and neurogenesis in naïve C57BL/6J mice. In contrast, both genetic knockdown of hippocampal miR-206-3p and intranasal administration of AntagomiR-206-3p produced significant antidepressant-like effects in the CSDS model of depression. Furthermore, it was found that the antidepressant-like effects induced by miR-206-3p inhibition require the hippocampal BDNF-TrkB system. Taken together, hippocampal miR-206-3p participates in the pathogenesis of depression by regulating BDNF biosynthesis and is a feasible antidepressant target.

Emerging Role of Non-coding RNAs in Autism Spectrum Disorder

Autism spectrum disorders (ASD) embrace a diverse set of neurodevelopmental diseases with a multifaceted genetic basis. Non-coding RNAs (ncRNAs) are among putative loci with critical participation in the development of ASD. Expression of some lncRNAs, namely RP11-466P24.2, SYP-AS1, STXBP5-AS1, and IFNG-AS1 has been decreased in ASD, while AK128569, CTD-2516F10.2, MSNP1AS, RPS10P2-AS1, LINC00693, LINC00689, NEAT1, TUG1, and Shank2-AS lncRNAs have been over-expressed in ASD. Expression of several miRNAs which are implicated in the immunological developmental, immune responses, and protein synthesis as well as those participating in the regulation of PI3K/Akt/mTOR and EGFR signaling pathways is dysregulated in the context of ASD. In the present article, we describe investigations which appraised the role of lncRNAs, miRNAs, and circRNAs in the pathobiology of ASD.

Prior nasal delivery of antagomiR-122 prevents radiation-induced brain injury

Radiation-induced brain injury is a major adverse event in head and neck tumor treatment, influencing the quality of life for the more than 50% of patients who undergo radiation therapy and experience long-term survival. However, no effective treatments are available for these patients, and preventative drugs and effective drug-delivery methods must be developed. Based on our results, miR-122-5p was upregulated in the mouse radiation-induced brain injury (RBI) model and patients with nasopharyngeal carcinoma (NPC) who received radiation therapy. Intranasal administration of a single antagomiR-122-5p dose before irradiation effectively alleviated radiation-induced cognitive impairment, neuronal injury, and neuroinflammation in the mouse RBI model. Results further indicated that miR-122-5p inhibition in microglia reduced the levels of proinflammatory cytokines and enhanced the phagocytic function to protect against radiation-induced neuronal injury in cell models. Further, we profiled transcriptome data and verified that Tensin 1 (TNS1) may be the target of miR-122-5p in RBI. In summary, our results reveal a distinct role for miR-122-5p in regulating neuroinflammation in RBI, indicating that a non-invasive strategy for intranasal miR-122-5p administration may be an attractive therapeutic target in RBI, providing new insights for clinical trials. Further systematic safety assessment, optimization of drug administration, and clarity of mechanism will accelerate the process into clinical practice.

miR-214 Alleviates Ischemic Stroke-Induced Neuronal Death by Targeting DAPK1 in Mice

BACKGROUND

Ischemic stroke induces neuronal cell death and causes brain dysfunction. Preventing neuronal cell death after stroke is key to protecting the brain from stroke damage. Nevertheless, preventative measures and treatment strategies for stroke damage are scarce. Emerging evidence suggests that microRNAs (miRNAs) play critical roles in the pathogenesis of central nervous system (CNS) disorders and may serve as potential therapeutic targets.

METHODS

A photochemically induced thrombosis (PIT) mouse model was used as an ischemic stroke model. qRT-PCR was employed to assess changes in miRNAs in ischemic lesions of PIT-stroke mice and primary cultured neurons subjected to oxygen-glucose deprivation (OGD). 2,3,5-triphenyltetrazolium chloride (TTC) staining was performed to evaluate brain infarction tissues in vivo. TUNEL staining was employed to assess neuronal death in vitro. Neurological scores and motor coordination were investigated to evaluate stroke damage, including neurological deficits and motor function.

RESULTS

In vivo and in vitro results demonstrated that levels of miR-124 were significantly decreased following stroke, whereas changes in death-associated protein kinase 1 (DAPK1) levels exhibited the converse pattern. DAPK1 was identified as a direct target of miR-124. N-methyl-D-aspartate (NMDA) and OGD-induced neuronal death was rescued by miR-124 overexpression. Upregulation of miR-124 levels significantly improved PIT-stroke damage, including the overall neurological function in mice.

CONCLUSION

We demonstrate the involvement of the miR-124/DAPK1 pathway in ischemic neuronal death. Our results highlight the therapeutic potential of targeting this pathway for ischemic stroke.

The Potential Role of Exosomes in Child and Adolescent Obesity

Child and adolescent obesity constitute one of the greatest contemporary public health menaces. The enduring disproportion between calorie intake and energy consumption, determined by a complex interaction of genetic, epigenetic, and environmental factors, finally leads to the development of overweight and obesity. Child and adolescent overweight/obesity promotes smoldering systemic inflammation (“para-inflammation”) and increases the likelihood of later metabolic and cardiovascular complications, including metabolic syndrome and its components, which progressively deteriorate during adulthood. Exosomes are endosome-derived extracellular vesicles that are secreted by a variety of cells, are naturally taken-up by target cells, and may be involved in many physiological and pathological processes. Over the last decade, intensive research has been conducted regarding the special role of exosomes and the non-coding (nc) RNAs they contain (primarily micro (mi) RNAs, long (l) non-coding RNAs, messenger (m) RNAs and other molecules) in inter-cellular communications. Through their action as communication mediators, exosomes may contribute to the pathogenesis of obesity and associated disorders. There is increasing evidence that exosomal miRNAs and lncRNAs are involved in pivotal processes of adipocyte biology and that, possibly, play important roles in gene regulation linked to human obesity. This review aims to improve our understanding of the roles of exosomes and their cargo in the development of obesity and related metabolic and inflammatory disorders. We examined their potential roles in adipose tissue physiology and reviewed the scarce data regarding the altered patterns of circulating miRNAs and lncRNAs observed in obese children and adolescents, compared them to the equivalent, more abundant existing findings of adult studies, and speculated on their proposed mechanisms of action. Exosomal miRNAs and lncRNAs could be applied as cardiometabolic risk biomarkers, useful in the early diagnosis and prevention of obesity. Furthermore, the targeting of crucial circulating exosomal cargo to tissues involved in the pathogenesis and maintenance of obesity could provide a novel therapeutic approach to this devastating and management-resistant pandemic.

Systematic Review and Bioinformatic Analysis of microRNA Expression in Autism Spectrum Disorder Identifies Pathways Associated With Cancer, Metabolism, Cell Signaling, and Cell Adhesion

Background: Previous studies have identified differentially expressed microRNAs in autism spectrum disorder (ASD), however, results are discrepant. We aimed to systematically review this topic and perform bioinformatic analysis to identify genes and pathways associated with ASD miRNAs. Methods: Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses, we searched the Web of Science, PubMed, Embase, Scopus, and OVID databases to identify all studies comparing microRNA expressions between ASD persons and non-ASD controls on May 11, 2020. We obtained ASD miRNA targets validated by experimental assays from miRTarBase and performed pathway enrichment analysis using Metascape and DIANA-miRPath v3. 0. Results: Thirty-four studies were included in the systematic review. Among 285 altered miRNAs reported in these studies, 15 were consistently upregulated, 14 were consistently downregulated, and 39 were inconsistently dysregulated. The most frequently altered miRNAs including miR-23a-3p, miR-106b-5p, miR-146a-5p, miR-7-5p, miR-27a-3p, miR-181b-5p, miR-486-3p, and miR-451a. Subgroup analysis of tissues showed that miR-146a-5p, miR-155-5p, miR-1277-3p, miR-21-3p, miR-106b-5p, and miR-451a were consistently upregulated in brain tissues, while miR-4742-3p was consistently downregulated; miR-23b-3p, miR-483-5p, and miR-23a-3p were consistently upregulated in blood samples, while miR-15a-5p, miR-193a-5p, miR-20a-5p, miR-574-3p, miR-92a-3p, miR-3135a, and miR-103a-3p were consistently downregulated; miR-7-5p was consistently upregulated in saliva, miR-23a-3p and miR-32-5p were consistently downregulated. The altered ASD miRNAs identified in at least two independent studies were validated to target many autism risk genes. TNRC6B, PTEN, AGO1, SKI, and SMAD4 were the most frequent targets, and miR-92a-3p had the most target autism risk genes. Pathway enrichment analysis showed that ASD miRNAs are significantly involved in pathways associated with cancer, metabolism (notably Steroid biosynthesis, Fatty acid metabolism, Fatty acid biosynthesis, Lysine degradation, Biotin metabolism), cell cycle, cell signaling (especially Hippo, FoxO, TGF-beta, p53, Thyroid hormone, and Estrogen signaling pathway), adherens junction, extracellular matrix-receptor interaction, and Prion diseases. Conclusions: Altered miRNAs in ASD target autism risk genes and are involved in various ASD-related pathways, some of which are understudied and require further investigation.