A non-canonical landscape of the microRNA system

The biology of chronic myeloid leukemia: an overview of the new insights and biomarkers

Chronic myeloid leukemia is one of the onco-hematologic diseases in which the identification of disease markers and therapeutic advances have been particularly impactful. Despite this, significant gaps remain in our understanding of disease pathogenesis, progression, mechanisms of immune escape, and resistance to standard therapies. Recently, advances in technology and biological knowledge have drawn attention to several promising areas of research. Among these, leukemic stem cells, miRNAs, extracellular vesicles, and additional BCR::ABL1 mutations, with particular reference to the ASXL1 gene, have been the most extensively investigated. In this review we summarized and critically commented the main findings on these key topics over the past 5 years, evaluating their potential impact on patient management and their role in the development of new therapeutic strategies.

miRNAs in radiotherapy resistance of cancer; a comprehensive review

While intensity-modulated radiation therapy-based comprehensive therapy increases outcomes, cancer patients still have a low five-year survival rate and a high recurrence rate. The primary factor contributing to cancer patients' poor prognoses is radiation resistance. A class of endogenous non-coding RNAs, known as microRNAs (miRNAs), controls various biological processes in eukaryotes. These miRNAs influence tumor cell growth, death, migration, invasion, and metastasis, which controls how human carcinoma develops and spreads. The correlation between the unbalanced expression of miRNAs and the prognosis and sensitivity to radiation therapy is well-established. MiRNAs have a significant impact on the regulation of DNA repair, the epithelial-to-mesenchymal transition (EMT), and stemness in the tumor radiation response. But because radio resistance is a complicated phenomena, further research is required to fully comprehend these mechanisms. Radiation response rates vary depending on the modality used, which includes the method of delivery, radiation dosage, tumor stage and grade, confounding medical co-morbidities, and intrinsic tumor microenvironment. Here, we summarize the possible mechanisms through which miRNAs contribute to human tumors' resistance to radiation.

Understanding the role of miRNAs in cervical cancer pathogenesis and therapeutic responses

Cervical cancer (CC) is the most common cancer in women and poses a serious threat to health. Despite familiarity with the factors affecting its etiology, initiation, progression, treatment strategies, and even resistance to therapy, it is considered a significant problem for women. However, several factors have greatly affected the previous aspects of CC progression and treatment in recent decades. miRNAs are short non-coding RNA sequences that regulate gene expression by inhibiting translation of the target mRNA. miRNAs play a crucial role in CC pathogenesis by promoting cancer stem cell (CSC) proliferation, postponing apoptosis, continuing the cell cycle, and promoting invasion, angiogenesis, and metastasis. Similarly, miRNAs influence important CC-related molecular pathways, such as the PI3K/AKT/mTOR signaling pathway, Wnt/β-catenin system, JAK/STAT signaling pathway, and MAPK signaling pathway. Moreover, miRNAs affect the response of CC patients to chemotherapy and radiotherapy. Consequently, this review aims to provide an acquainted summary of onco miRNAs and tumor suppressor (TS) miRNAs and their potential role in CC pathogenesis and therapy responses by focusing on the molecular pathways that drive them.

Radio-miRs: a comprehensive view of radioresistance-related microRNAs

Radiotherapy is a key treatment option for a wide variety of human tumors, employed either alone or alongside with other therapeutic interventions. Radiotherapy uses high-energy particles to destroy tumor cells, blocking their ability to divide and proliferate. The effectiveness of radiotherapy is due to genetic and epigenetic factors that determine how tumor cells respond to ionizing radiation. These factors contribute to the establishment of resistance to radiotherapy, which increases the risk of poor clinical prognosis of patients. Although the mechanisms by which tumor cells induce radioresistance are unclear, evidence points out several contributing factors including the overexpression of DNA repair systems, increased levels of reactive oxygen species, alterations in the tumor microenvironment, and enrichment of cancer stem cell populations. In this context, dysregulation of microRNAs or miRNAs, critical regulators of gene expression, may influence how tumors respond to radiation. There is increasing evidence that miRNAs may act as sensitizers or enhancers of radioresistance, regulating key processes such as the DNA damage response and the cell death signaling pathway. Furthermore, expression and activity of miRNAs have shown informative value in overcoming radiotherapy and long-term radiotoxicity, revealing their potential as biomarkers. In this review, we will discuss the molecular mechanisms associated with the response to radiotherapy and highlight the central role of miRNAs in regulating the molecular mechanisms responsible for cellular radioresistance. We will also review radio-miRs, radiotherapy-related miRNAs, either as sensitizers or enhancers of radioresistance that hold promise as biomarkers or pharmacological targets to sensitize radioresistant cells.

Network Analysis Performed on Transcriptomes of Parkinson's Disease Patients Reveals Dysfunction in Protein Translation

Parkinson's disease (PD) is a prevalent neurodegenerative disorder characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra region of the brain. The hallmark pathological feature of PD is the accumulation of misfolded proteins, leading to the formation of intracellular aggregates known as Lewy bodies. Recent data evidenced how disruptions in protein synthesis, folding, and degradation are events commonly observed in PD and may provide information on the molecular background behind its etiopathogenesis. In the present study, we used a publicly available transcriptomic microarray dataset of peripheral blood of PD patients and healthy controls (GSE6613) to investigate the potential dysregulation of elements involved in proteostasis-related processes at the transcriptomic level. Our bioinformatics analysis revealed 375 differentially expressed genes (DEGs), of which 281 were down-regulated and 94 were up-regulated. Network analysis performed on the observed DEGs highlighted a cluster of 36 elements mainly involved in the protein synthesis processes. Different enriched ontologies were related to translation initiation and regulation, ribosome structure, and ribosome components nuclear export. Overall, this data consistently points to a generalized impairment of the translational machinery and proteostasis. Dysregulation of these mechanics has been associated with PD pathogenesis. Understanding the precise regulation of such processes may shed light on the molecular mechanisms of PD and provide potential data for early diagnosis.

Extracellular vesicles-associated miRNAs in triple-negative breast cancer: from tumor biology to clinical relevance

Breast cancer (BC), a heterogeneous group of diseases, is the most frequent type and the leading cause of cancer-related death among women worldwide. Tumor heterogeneity directly impacts cancer progression and treatment, as evidenced by the patients´ diverse prognosis and treatment responses across the distinct molecular subtypes. Triple-negative breast cancer (TNBC), which accounts for 10-20% of all diagnosed BC cases, is an aggressive BC subtype with a challenging prognosis. Current treatment options include systemic chemotherapy and/or target therapies based on PARP and PD-L1 inhibitors for eligible patients. MicroRNAs (miRNAs) are important regulatory non-coding RNAs (ncRNAs) in TNBC tumorigenesis. These molecules are present both intracellularly and released into biofluids, packaged into extracellular vesicles (EVs). Emerging evidence indicates that EVs-associated miRNAs (EVs-miRNAs), transferred from parental to recipient cells, are key mediators of cell-to-cell communication. Considering their stability and abundance in several biofluids, these molecules may reflect the epigenomic composition of their tumors of origin and contribute to mediate tumorigenesis, similar to their intracellular counterparts. This review provides the current knowledge on EVs-miRNAs in the TNBC subtype, focusing on their role in regulating mRNA targets involved in tumor phenotypes and their clinical relevance as promising biomarkers in liquid biopsies.

microRNA-dependent regulation of gene expression in GABAergic interneurons

Information processing within neuronal circuits relies on their proper development and a balanced interplay between principal and local inhibitory interneurons within those circuits. Gamma-aminobutyric acid (GABA)ergic inhibitory interneurons are a remarkably heterogeneous population, comprising subclasses based on their morphological, electrophysiological, and molecular features, with differential connectivity and activity patterns. microRNA (miRNA)-dependent post-transcriptional control of gene expression represents an important regulatory mechanism for neuronal development and plasticity. miRNAs are a large group of small non-coding RNAs (21-24 nucleotides) acting as negative regulators of mRNA translation and stability. However, while miRNA-dependent gene regulation in principal neurons has been described heretofore in several studies, an understanding of the role of miRNAs in inhibitory interneurons is only beginning to emerge. Recent research demonstrated that miRNAs are differentially expressed in interneuron subclasses, are vitally important for migration, maturation, and survival of interneurons during embryonic development and are crucial for cognitive function and memory formation. In this review, we discuss recent progress in understanding miRNA-dependent regulation of gene expression in interneuron development and function. We aim to shed light onto mechanisms by which miRNAs in GABAergic interneurons contribute to sculpting neuronal circuits, and how their dysregulation may underlie the emergence of numerous neurodevelopmental and neuropsychiatric disorders.

Exosome Carrier Effects; Resistance to Digestion in Phagolysosomes May Assist Transfers to Targeted Cells; II Transfers of miRNAs Are Better Analyzed via Systems Approach as They Do Not Fit Conventional Reductionist Stoichiometric Concepts

Carrier effects of extracellular vesicles (EV) like exosomes refer to properties of the vesicles that contribute to the transferred biologic effects of their contents to targeted cells. This can pertain to ingested small amounts of xenogeneic plant miRNAs and oral administration of immunosuppressive exosomes. The exosomes contribute carrier effects on transfers of miRNAs by contributing both to the delivery and the subsequent functional intracellular outcomes. This is in contrast to current quantitative canonical rules that dictate just the minimum copies of a miRNA for functional effects, and thus successful transfers, independent of the EV carrier effects. Thus, we argue here that transfers by non-canonical minute quantities of miRNAs must consider the EV carrier effects of functional low levels of exosome transferred miRNA that may not fit conventional reductionist stoichiometric concepts. Accordingly, we have examined traditional stoichiometry vs. systems biology that may be more appropriate for delivered exosome functional responses. Exosome carrier properties discussed include; their required surface activating interactions with targeted cells, potential alternate targets beyond mRNAs, like reaching a threshold, three dimensional aspects of the RNAs, added EV kinetic dynamic aspects making transfers four dimensional, and unique intracellular release from EV that resist intracellular digestion in phagolysosomes. Together these EV carrier considerations might allow systems analysis. This can then result in a more appropriate understanding of transferred exosome carrier-assisted functional transfers. A plea is made that the miRNA expert community, in collaboration with exosome experts, perform new experiments on molecular and quantitative miRNA functional effects in systems that include EVs, like variation in EV type and surface constituents, delivery, dose and time to hopefully create more appropriate and truly current canonical concepts of the consequent miRNA functional transfers by EVs like exosomes.

The Role of MicroRNAs in Proteostasis Decline and Protein Aggregation during Brain and Skeletal Muscle Aging

Aging can be defined as the progressive deterioration of cellular, tissue, and organismal function over time. Alterations in protein homeostasis, also known as proteostasis, are a hallmark of aging that lead to proteome imbalances and protein aggregation, phenomena that also occur in age-related diseases. Among the various proteostasis regulators, microRNAs (miRNAs) have been reported to play important roles in the post-transcriptional control of genes involved in maintaining proteostasis during the lifespan in several organismal tissues. In this review, we consolidate recently published reports that demonstrate how miRNAs regulate fundamental proteostasis-related processes relevant to tissue aging, with emphasis on the two most studied tissues, brain tissue and skeletal muscle. We also explore an emerging perspective on the role of miRNA regulatory networks in age-related protein aggregation, a known hallmark of aging and age-related diseases, to elucidate potential miRNA candidates for anti-aging diagnostic and therapeutic targets.

MicroRNAs and Stem-like Properties: The Complex Regulation Underlying Stemness Maintenance and Cancer Development

Embryonic stem cells (ESCs) have the extraordinary properties to indefinitely proliferate and self-renew in culture to produce different cell progeny through differentiation. This latter process recapitulates embryonic development and requires rounds of the epithelial-mesenchymal transition (EMT). EMT is characterized by the loss of the epithelial features and the acquisition of the typical phenotype of the mesenchymal cells. In pathological conditions, EMT can confer stemness or stem-like phenotypes, playing a role in the tumorigenic process. Cancer stem cells (CSCs) represent a subpopulation, found in the tumor tissues, with stem-like properties such as uncontrolled proliferation, self-renewal, and ability to differentiate into different cell types. ESCs and CSCs share numerous features (pluripotency, self-renewal, expression of stemness genes, and acquisition of epithelial-mesenchymal features), and most of them are under the control of microRNAs (miRNAs). These small molecules have relevant roles during both embryogenesis and cancer development. The aim of this review was to recapitulate molecular mechanisms shared by ESCs and CSCs, with a special focus on the recently identified classes of microRNAs (noncanonical miRNAs, mirtrons, isomiRs, and competitive endogenous miRNAs) and their complex functions during embryogenesis and cancer development.

Targeting microRNA-mediated gene repression limits adipogenic conversion of skeletal muscle mesenchymal stromal cells

Intramuscular fatty deposits, which are seen in muscular dystrophies and with aging, negatively affect muscle function. The cells of origin of adipocytes constituting these fatty deposits are mesenchymal stromal cells, fibroadipogenic progenitors (FAPs). We uncover a molecular fate switch, involving miR-206 and the transcription factor Runx1, that controls FAP differentiation to adipocytes. Mice deficient in miR-206 exhibit increased adipogenesis following muscle injury. Adipogenic differentiation of FAPs is abrogated by miR-206 mimics. Using a labeled microRNA (miRNA) pull-down and sequencing (LAMP-seq), we identified Runx1 as a miR-206 target, with miR-206 repressing Runx1 translation. In the absence of miR-206 in FAPs, Runx1 occupancy near transcriptional start sites of adipogenic genes and expression of these genes increase. We demonstrate that miR-206 mimicry in vivo limits intramuscular fatty infiltration. Our results provide insight into the underlying molecular mechanisms of FAP fate determination and formation of harmful fatty deposits in skeletal muscle.

Competing Endogenous RNAs in Cervical Carcinogenesis: A New Layer of Complexity

MicroRNAs (miRNAs) regulate gene expression by binding to complementary sequences within target mRNAs. Apart from working ‘solo’, miRNAs may interact in important molecular networks such as competing endogenous RNA (ceRNA) axes. By competing for a limited pool of miRNAs, transcripts such as long noncoding RNAs (lncRNAs) and mRNAs can regulate each other, fine-tuning gene expression. Several ceRNA networks led by different lncRNAs—described here as lncRNA-mediated ceRNAs—seem to play essential roles in cervical cancer (CC). By conducting an extensive search, we summarized networks involved in CC, highlighting the major impacts of such dynamic molecular changes over multiple cellular processes. Through the sponging of distinct miRNAs, some lncRNAs as HOTAIR, MALAT1, NEAT1, OIP5-AS1, and XIST trigger crucial molecular changes, ultimately increasing cell proliferation, migration, invasion, and inhibiting apoptosis. Likewise, several lncRNAs seem to be a sponge for important tumor-suppressive miRNAs (as miR-140-5p, miR-143-3p, miR-148a-3p, and miR-206), impairing such molecules from exerting a negative post-transcriptional regulation over target mRNAs. Curiously, some of the involved mRNAs code for important proteins such as PTEN, ROCK1, and MAPK1, known to modulate cell growth, proliferation, apoptosis, and adhesion in CC. Overall, we highlight important lncRNA-mediated functional interactions occurring in cervical cells and their closely related impact on cervical carcinogenesis.

Subcellular Localization of MicroRNAs by MicroRNA In Situ Hybridization (miR-ISH)

MicroRNAs (miRNAs) are 22-nucleotide RNA sequences that regulate up to 60% of the mammalian transcriptome. Although canonical miRNA-induced silencing complex-mediated messenger RNA degradation occurs in the cytoplasm, miRNAs have been described in other subcellular compartments with potentially novel functions. Currently, there are limited methodologies for visualizing RNA locations within cells to elucidate mechanisms and pathways of miRNA biogenesis, transport, and function. Here, we describe a simple and rapid miRNA in situ hybridization method that can be combined with standard immunofluorescence procedures for subcellular localization of mature and precursor miRNAs.

Diagnostic, Prognostic, and Therapeutic Value of Non-Coding RNA Expression Profiles in Renal Transplantation

End-stage renal disease is a public health problem responsible for millions of deaths worldwide each year. Although transplantation is the preferred treatment for patients in need of renal replacement therapy, long-term allograft survival remains challenging. Advances in high-throughput methods for large-scale molecular data generation and computational analysis are promising to overcome the current limitations posed by conventional diagnostic and disease classifications post-transplantation. Non-coding RNAs (ncRNAs) are RNA molecules that, despite lacking protein-coding potential, are essential in the regulation of epigenetic, transcriptional, and post-translational mechanisms involved in both health and disease. A large body of evidence suggests that ncRNAs can act as biomarkers of renal injury and graft loss after transplantation. Hence, the focus of this review is to discuss the existing molecular signatures of non-coding transcripts and their value to improve diagnosis, predict the risk of rejection, and guide therapeutic choices post-transplantation.

Methylation analysis of MIR200 family in Mexican patients with colorectal cancer

The present study aimed to analyze the methylation pattern of the MIR200 family in the colorectal tissues and peripheral blood of colorectal cancer (CRC) patients. Previous informed consent, 102 samples of colorectal tissues (tumor and adjacent normal tissues) and 40 peripheral blood samples were collected from CRC patients. Additionally, we included a reference group of 40 blood samples. DNA extraction was done for colorectal tissues and peripheral blood. For methylation-specific PCR, we used bisulfite-treated DNA and controls for methylated and unmethylated DNA were included to each assay. PCR fragments were separated by 6% polyacrylamide gel electrophoresis. Methylation-positive and methylation-negative results were confirmed by bisulfite genomic sequencing technique. We analyzed 102 colorectal tissues and 40 blood samples from 51 CRC patients. MIR200B/MIR200A/MIR429 methylation analysis discloses no differences among tissues (p>0.05). However, MIR200C/MIR141 methylation showed differences between colorectal tissues and peripheral blood of CRC patients (p<0.0001) and mainly methylated alleles were observed in peripheral blood. These findings suggest a tissue-specific methylation pattern for the MIR200C/MIR141 promoter.

Functional impact of microRNA regulation in models of extreme stress adaptation

When confronted with severe environmental stress, some animals are able to undergo a substantial reorganization of their cellular environment that enables long-term survival. One molecular mechanism of adaptation that has received considerable attention in recent years has been the action of reversible transcriptome regulation by microRNA. The implementation of new computational and high-throughput experimental approaches has started to uncover the vital contributions of microRNA towards stress adaptation. Indeed, recent studies have suggested that microRNA may have a major regulatory influence over a number of cellular processes that are essential to prolonged environmental stress survival. To date, a number of studies have highlighted the role of microRNA in the regulation of a metabolically depressed state, documenting stress-responsive microRNA expression during mammalian hibernation, frog and insect freeze tolerance, and turtle and marine snail anoxia tolerance. These studies collectively indicate a conserved principle of microRNA stress response across phylogeny. As we are on the verge of dissecting the role of microRNA in environmental stress adaptation, this review summarizes recent research advances and the hallmark expression patterns that facilitate stress survival.

MicroRNA-223 Suppresses the Canonical NF-κB Pathway in Basal Keratinocytes to Dampen Neutrophilic Inflammation

MicroRNA-223 is known as a myeloid-enriched anti-inflammatory microRNA that is dysregulated in numerous inflammatory conditions. Here, we report that neutrophilic inflammation (wound response) is augmented in miR-223-deficient zebrafish, due primarily to elevated activation of the canonical nuclear factor κB (NF-κB) pathway. NF-κB over-activation is restricted to the basal layer of the surface epithelium, although miR-223 is detected throughout the epithelium and in phagocytes. Not only phagocytes but also epithelial cells are involved in miR-223-mediated regulation of neutrophils' wound response and NF-κB activation. Cul1a/b, Traf6, and Tab1 are identified as direct targets of miR-223, and their levels rise in injured epithelium lacking miR-223. In addition, miR-223 is expressed in cultured human bronchial epithelial cells, where it also downregulates NF-κB signaling. Together, this direct connection between miR-223 and the canonical NF-κB pathway provides a mechanistic understanding of the multifaceted role of miR-223 and highlights the relevance of epithelial cells in dampening neutrophil activation.

miR-188-5p emerges as an oncomiRNA to promote gastric cancer cell proliferation and migration via upregulation of SALL4

MicroRNAs (miRNAs) play pivotal roles in modulating key biological processes in gastric cancer (GC). As a newly identified miRNA, the function and potential mechanism of miR-188-5p in GC has not been thoroughly elucidated. Here, quantitative real-time polymerase chain reaction detection showed abnormally higher expression of miR-188-5p in GC cells and tissues. Gain-of-function analysis in vitro showed that miR-188-5p promoted GC cell proliferation and migration, while loss-of-function studies showed the reverse. Targetscan has predicted that phosphatase and tensin homolog (PTEN) was a potential target gene of miR-188-5p. miR-188-5p suppressed PTEN messenger RNA and protein expression and activated downstream AKT/mTOR signaling in GC cells, but luciferase reporter analysis showed that PTEN was not regulated by miR-188-5p via the 3' untranslated region. Furthermore, we observed that miR-188-5p overexpression promoted Sal-like protein 4 (SALL4) protein expression, cellular nuclear translocation, and transcription. Knockdown of SALL4 eliminated the effect of miR-188-5p in GC cells as well as suppression of PTEN. Taken together, our results demonstrate that miR-188-5p promotes GC cell proliferation and migration while suppressing tumor suppressor gene PTEN expression via transcriptional upregulation of oncogene SALL4. We conclude that miR-188-5p acts as an oncomiRNA in GC and may be a promising therapeutic target for GC.

Epigenetic signature for attention-deficit/hyperactivity disorder: identification of miR-26b-5p, miR-185-5p, and miR-191-5p as potential biomarkers in peripheral blood mononuclear cells

Attention-deficit/hyperactivity disorder (ADHD) is one of the most prevalent neurodevelopmental disorders in childhood and persists into adulthood in 40-65% of cases. Given the polygenic and heterogeneous architecture of the disorder and the limited overlap between genetic studies, there is a growing interest in epigenetic mechanisms, such as microRNAs, that modulate gene expression and may contribute to the phenotype. We attempted to clarify the role of microRNAs in ADHD at a molecular level through the first genome-wide integrative study of microRNA and mRNA profiles in peripheral blood mononuclear cells of medication-naive individuals with ADHD and healthy controls. We identified 79 microRNAs showing aberrant expression levels in 56 ADHD cases and 69 controls, with three of them, miR-26b-5p, miR-185-5p, and miR-191-5p, being highly predictive for diagnostic status in an independent dataset of 44 ADHD cases and 46 controls. Investigation of downstream microRNA-mediated mechanisms underlying the disorder, which was focused on differentially expressed, experimentally validated target genes of the three highly predictive microRNAs, provided evidence for aberrant myo-inositol signaling in ADHD and indicated an enrichment of genes involved in neurological disease and psychological disorders. Our comprehensive study design reveals novel microRNA-mRNA expression profiles aberrant in ADHD, provides novel insights into microRNA-mediated mechanisms contributing to the disorder, and highlights promising candidate peripheral biomarkers.

Protective Action of Diazoxide on Isoproterenol-Induced Hypertrophy Is Mediated by Reduction in MicroRNA-132 Expression

INTRODUCTION AND METHODS

The effects of diazoxide on cardiac hypertrophy and miR-132 expression were characterized in adult rats and in cardiomyocytes. Diazoxide effects on reactive oxygen species (ROS) production and on the cAMP-response element binding (CREB) transcription factor's abundance in cardiomyocytes were also analyzed. ROS measurements used a fluorescent dye. Western blot analysis and quantitative Reverse Transcription Polymerase Chain Reaction were used to measure phosphorylated form of CREB (pCREB) abundance and miR-132 expression, respectively.

RESULTS

Isoproterenol (ISO) induced cardiac hypertrophy, an effect that was mitigated by diazoxide. The rate of ROS production, CREB phosphorylation, and miR-132 expression increased after the addition of ISO. H2O2 increased pCREB abundance and miR-132 expression; upregulation of miR-132 was blocked by the specific inhibitor of CREB transcription, 666-15. Consistent with a role of ROS on miR-132 expression, diazoxide prevented the increase in ROS production, miR-132 expression, and pCREB abundance produced by ISO. Phosphorylation of CREB by ISO was prevented by U0126, an inhibitor of mitogen-activated protein kinase.

CONCLUSIONS

Our data first demonstrate that diazoxide mitigates hypertrophy by preventing an increase in miR-132 expression. The mechanism likely involves less ROS production leading to less phosphorylation of CREB. Our data further show that ROS enhance miR-132 transcription, and that ISO effects are probably mediated by the mitogen-activated protein kinase pathway.

MicroRNA-103 Promotes Proliferation and Inhibits Apoptosis in Spinal Osteosarcoma Cells by Targeting p57

Osteosarcoma is one of the most aggressive malignancies with poor prognosis rates. Many studies have demonstrated that miRNAs were involved in osteosarcoma, but the role of miR-103a in osteosarcoma remains elusive. In this study, we detected the expression levels of miR-103 in osteosarcoma and non-osteosarcoma tissues and cell lines. The binding effect of miR-103 on p57 was detected by luciferase reporter assay. After altering expressions of miR-103 or p57, viability, migration, invasion, and apoptosis of MG63 cells and expressions of proteins related with the JNK/STAT and mTOR pathways were all detected. We found the higher expression of miR-103 in osteosarcoma tissues and cell lines compared with non-osteosarcoma tissues and cell lines. miR-103 overexpression promoted survival, migration, and invasion of MG63 cells. Knockdown of miR-103a inhibited cell survival, migration, and invasion by upregulating the expression of p57, which was a target of miR-103. Moreover, miR-103a overexpression activated the JNK/STAT and mTOR pathways probably through inhibiting p57 expression. In conclusion, miR-103a acted as an oncogene in osteosarcoma, probably through activating the JNK/STAT and mTOR pathways by inhibiting p57 expression.

Differential Expression of microRNAs in Peripheral Blood Mononuclear Cells Identifies Autophagy and TGF-Beta-Related Signatures Aberrantly Expressed in Inflammatory Bowel Disease

BACKGROUND AND AIMS

MicroRNAs [miRNAs] have emerged as important regulators in inflammatory bowel disease [IBD]. This study investigated differential expression of miRNAs across clinical phenotypes in a well-characterized cohort of IBD patients and healthy controls [HCs].

METHODS

A cohort of Crohn's disease [CD] and ulcerative colitis [UC] patients and HCs was prospectively accrued. Total RNA was extracted from peripheral blood mononuclear cells for all subjects. miRNA expression was measured using NanoString technologies. The subjects were stratified according to disease activity and location. Statistical significance was assessed per miRNA across outcomes and corrected for multiple testing. miRNA regulation of transcription of important results was confirmed in vitro by a dual luciferase reporter assay and autophagy function was evaluated using immunofluorescence imaging of LC3 puncta in HeLa cells.

RESULTS

In total, 120 subjects were enrolled. Seventy-four miRNAs were differentially expressed across CD, UC and HCs. Comparing quiescent CD [CDq] with HCs we found ten miRNAs upregulated in CDq. When comparing colonic CD [CCD] to UC, seven miRNAs were upregulated in CCD. The most differentially expressed miRNA in CCD vs UC was miR-874-3p, and we showed its possible utility as a biomarker of differential diagnosis. We showed miR-874-3p targets ATG16L1 and reduces its expression in vitro. An miR-874-3p mimic dysregulates autophagy by a reduction of LC3 in vitro.

CONCLUSIONS

We identified unique miRNA signatures expressed in distinct IBD phenotypes. These associations highlight pathways dysregulated by aberrant miRNA expression, revealing possible mechanisms underlying the pathophysiology of IBD, but also suggest a cluster of miRNAs as readily accessible biomarkers to aid in differential diagnosis.

miR-21-5p as a potential biomarker of inflammatory infiltration in the heart upon acute drug-induced cardiac injury in rats

Investigation of genomic changes in cardiotoxicity can provide novel biomarkers and insights into molecular mechanisms of drug-induced cardiac injury (DICI). The main objective of this study was to identify and characterize dysregulated microRNAs (miRNAs) in the heart associated with cardiotoxicity. Wistar rats were dosed once with either isoproterenol (1.5 mg/kg, i.p), allylamine (100 mg/kg, p.o.) or the respective vehicle controls. Heart tissue was collected at 24 h, 48 h and 72 h post-drug administration and used for histopathological assessment, miRNA profiling, immunohistochemical analysis and in situ hybridization. Multiplex analysis of 68 miRNAs in the heart revealed a significant upregulation of several miRNAs (miR-19a-3p, miR-142-3p, miR-155-5p, miR-208b-3p, miR-21-5p) after isoproterenol and one miRNA (miR-21-5p) after allylamine administration. Localization of miR-21-5p was specific to inflammatory cell infiltrates in the heart after both treatments. Immunohistochemical analysis of Stat3, a known miR-21-5p regulator, also confirmed its upregulation in cardiomyocytes and inflammatory cell infiltrates. The toxicity signatures based on miRNA networks, identified in vivo, can potentially be used as mechanistic biomarkers as well as to study cardiotoxicity in vitro in order to develop sensitive tools for early hazard identification and risk assessment.

miRNAs, Melanoma and Microenvironment: An Intricate Network

miRNAs are central players in cancer biology and they play a pivotal role in mediating the network communication between tumor cells and their microenvironment. In melanoma, miRNAs can impair or facilitate a wide array of processes, and here we will focus on: the epithelial to mesenchymal transition (EMT), the immune milieu, and metabolism. Multiple miRNAs can affect the EMT process, even at a distance, for example through exosome-mediated mechanisms. miRNAs also strongly act on some components of the immune system, regulating the activity of key elements such as antigen presenting cells, and can facilitate an immune evasive/suppressive phenotype. miRNAs are also involved in the regulation of metabolic processes, specifically in response to hypoxic stimuli where they can mediate the metabolic switch from an oxidative to a glycolytic metabolism. Overall, this review discusses and summarizes recent findings on miRNA regulation in the melanoma tumor microenvironment, analyzing their potential diagnostic and therapeutic applications.

The evidence for a microRNA product of human DROSHA gene

MicroRNAs are short RNA molecules that regulate function and stability of a large subset of eukaryotic mRNAs. In the main pathway of microRNA biogenesis, a short "hairpin" is excised from a primary transcript by ribonuclease DROSHA, followed by additional nucleolytic processing by DICER and inclusion of the mature microRNA into the RNA-induced silencing complex. We report that a microRNA-like molecule is encoded by human DROSHA gene within a predicted stem-loop element of the respective transcript. This putative mature microRNA is complementary to DROSHA transcript variant 1 and can attenuate expression of the corresponding protein. The findings suggest a possibility for a negative feedback loop, wherein DROSHA processes its own transcript and produces an inhibitor of its own biosynthesis.

Animal Models to Study MicroRNA Function

The discovery of the microRNAs, lin-4 and let-7 as critical mediators of normal development in Caenorhabditis elegans and their conservation throughout evolution has spearheaded research toward identifying novel roles of microRNAs in other cellular processes. To accurately elucidate these fundamental functions, especially in the context of an intact organism, various microRNA transgenic models have been generated and evaluated. Transgenic C. elegans (worms), Drosophila melanogaster (flies), Danio rerio (zebrafish), and Mus musculus (mouse) have contributed immensely toward uncovering the roles of multiple microRNAs in cellular processes such as proliferation, differentiation, and apoptosis, pathways that are severely altered in human diseases such as cancer. The simple model organisms, C. elegans, D. melanogaster, and D. rerio, do not develop cancers but have proved to be convenient systesm in microRNA research, especially in characterizing the microRNA biogenesis machinery which is often dysregulated during human tumorigenesis. The microRNA-dependent events delineated via these simple in vivo systems have been further verified in vitro, and in more complex models of cancers, such as M. musculus. The focus of this review is to provide an overview of the important contributions made in the microRNA field using model organisms. The simple model systems provided the basis for the importance of microRNAs in normal cellular physiology, while the more complex animal systems provided evidence for the role of microRNAs dysregulation in cancers. Highlights include an overview of the various strategies used to generate transgenic organisms and a review of the use of transgenic mice for evaluating preclinical efficacy of microRNA-based cancer therapeutics.

MicroRNAs in neutrophils: potential next generation therapeutics for inflammatory ailments

Neutrophils play fundamental roles in both acute and chronic inflammatory conditions, and directly contribute to the immune pathologies in both infectious and autoimmune ailments. MicroRNAs (miRs) regulate homeostasis in health and disease by fine tuning the expression of a network of genes through post-transcriptional regulation. Many miRs are expressed in restricted tissues, regulated by stress and disease, and are emerging as mediators for intercellular communication. MiR profiles have been recently utilized as biomarkers for diagnosis and prognostic purposes. In addition, several miRs are in clinical development for various diseases. A short list of miRs that regulate hematopoiesis and neutrophil development is identified. Unfortunately, very limited information is available regarding how miRs regulate neutrophil migration and activation in vivo. Extensive future work is required, especially in animal models such as mice, to illustrate the pivotal and complex miR-mediated regulatory network. In addition, zebrafish, a vertebrate model organism with conserved innate immunity, potentiated by the availability of imaging and genetic tools, will provide a platform for rapid discovery and characterization of miRs that are relevant to neutrophilic inflammation. Advances in this field are expected to provide the foundation for highly selective miR-based therapy to manipulate neutrophils in infection and inflammatory disorders.

MicroRNAs in Pregnancy and Gestational Diabetes Mellitus: Emerging Role in Maternal Metabolic Regulation

PURPOSE OF THE REVIEW

This review focuses on the recent emergence of microRNAs (miRNAs) as metabolic and developmental regulators in pregnancy and their role in the development of gestational diabetes mellitus (GDM). MiRNAs are short and stable RNA sequences that repress protein synthesis through interference with messenger RNA translation.

RECENT FINDINGS

The placenta produces numerous miRNAs with some of them being released in the maternal circulation. These miRNA genes are encoded into specific clusters and expressed preferentially by placental cells, in a time-dependent manner. They were shown to be dysregulated in plasma and placenta from women suffering from GDM and associated with pregnancy and birth-related outcomes. The discovery of pregnancy-related miRNAs and their respective characterization will provide us with important information as to their function in maternal and placental metabolic regulation. More studies are needed to determine whether they will be useful for early screening of GDM.

A Macro View of MicroRNAs: The Discovery of MicroRNAs and Their Role in Hematopoiesis and Hematologic Disease

MicroRNAs (MiRNAs) are a class of endogenously encoded ~22 nucleotide, noncoding, single-stranded RNAs that contribute to development, body planning, stem cell differentiation, and tissue identity through posttranscriptional regulation and degradation of transcripts. Given their importance, it is predictable that dysregulation of MiRNAs, which target a wide variety of transcripts, can result in malignant transformation. In this review, we explore the discovery of MiRNAs, their mechanism of action, and the tools that aid in their discovery and study. Strikingly, many of the studies that have expanded our understanding of the contributions of MiRNAs to normal physiology and in the development of diseases have come from studies in the hematopoietic system and hematologic malignancies, with some of the earliest identified functions for mammalian MiRNAs coming from observations made in leukemias. So, with a special focus on the hematologic system, we will discuss how MiRNAs contribute to differentiation of stem cells and how dysregulation of MiRNAs contributes to the development of malignancy, by providing examples of specific MiRNAs that function as oncogenes or tumor suppressors, as well as of defects in MiRNA processing. Finally, we will discuss the promise of MiRNA-based therapeutics and challenges for the future study of disease-causing MiRNAs.

MiR-146a/b: a family with shared seeds and different roots

MicroRNAs are small, noncoding, RNAs known for their powerful modulation of molecular processes, making them a major focus for studying pathological mechanisms. The human miR-146 family of microRNAs consists of two member genes, MIR146A and MIR146B These two microRNAs are located on different chromosomes and exhibit differential regulation in many cases. However, they are nearly identical in sequence, sharing a seed region, and are thus predicted to target the same set of genes. A large proportion of the microRNA (miR)-146 literature focuses on its role in regulating the innate immune response in the context of various pathologies by modulating two widely studied target genes in the toll-like receptor signaling cascade. A growing subset of the literature reports a role of miR-146 in cardiovascular and renal disease, and data suggest there is exciting potential for miR-146 as a diagnostic and therapeutic target. Nevertheless, the published literature is confounded by unclear and imprecise language concerning the specific effects of the two miR-146 family members. The present review will compare the genomic origin and regulation of miR-146a and miR-146b, discuss some approaches to overcome analytical and experimental challenges, and summarize findings in major areas of miR-146 research. Moving forward, careful evaluation of miR-146a/b specificity in analytical and experimental approaches will aid researchers in elucidating the functional relevance of differential regulation of the miR-146 family members in health and disease.

Alterations in micro RNA-messenger RNA (miRNA-mRNA) Coupled Signaling Networks in Sporadic Alzheimer's Disease (AD) Hippocampal CA1

RNA sequencing, DNA microfluidic array, LED-Northern, Western immunoassay and bioinformatics analysis have uncovered a small family of up-regulated human brain enriched microRNAs (miRNAs) and down-regulated messenger RNAs (mRNAs) in short post-mortem interval (PMI) sporadic Alzheimer's disease (AD) brain. At the mRNA level, a large majority of the expression of human brain genes found to be down-regulated in sporadic AD appears to be a consequence of an up-regulation of a specific group of NF-kB-inducible microRNAs (miRNAs). This group of up-regulated miRNAs - including miRNA-34a and miRNA-146a - has strong, energetically favorable, complimentary RNA sequences in the 3' untranslated regions (3'-UTR) of their target mRNAs which ultimately drive the down-regulation in the expression of certain essential brain genes. Interestingly, just 2 significantly up-regulated miRNAs - miRNA-34a and miRNA-146a - appear to down-regulate mRNA targets involved in synaptogenesis (SHANK3), phagocytosis deficits and tau pathology (TREM2), inflammation (CFH; complement factor H) and amyloidogenesis (TSPAN12), all of which are distinguishing pathological features characteristic of middle-to-late stage AD neuropathology. This paper reports the novel finding of parallel miRNA-34a and miRNA-146a up-regulation in sporadic AD hippocampal CA1 RNA pools and proposes an altered miRNA-mRNA coupled signaling network in AD, much of which is supported by current experimental findings in the recent literature.

Role of microRNAs in translation regulation and cancer

MicroRNAs (miRNAs) are pervasively expressed and regulate most biological functions. They function by modulating transcriptional and translational programs and therefore they orchestrate both physiological and pathological processes, such as development, cell differentiation, proliferation, apoptosis and tumor growth. miRNAs work as small guide molecules in RNA silencing, by negatively regulating the expression of several genes both at mRNA and protein level, by degrading their mRNA target and/or by silencing translation. One of the most recent advances in the field is the comprehension of their role in oncogenesis. The number of miRNA genes is increasing and an alteration in the level of miRNAs is involved in the initiation, progression and metastases formation of several tumors. Some tumor types show a distinct miRNA signature that distinguishes them from normal tissues and from other cancer types. Genetic and biochemical evidence supports the essential role of miRNAs in tumor development. Although the abnormal expression of miRNAs in cancer cells is a widely accepted phenomenon, the cause of this dysregulation is still unknown. Here, we discuss the biogenesis of miRNAs, focusing on the mechanisms by which they regulate protein synthesis. In addition we debate on their role in cancer, highlighting their potential to become therapeutic targets.

Use of Mature miRNA Strand Selection in miRNAs Families in Cervical Cancer Development

Aberrant miRNA expression is well recognized as a cancer hallmark, nevertheless miRNA function and expression does not always correlate in patients tissues and cell lines studies. In addition to this issue, miRNA strand usage conduces to increased cell signaling pathways modulation diversifying cellular processes regulation. In cervical cancer, 20 miRNA families are involved in carcinogenesis induction and development to this moment. These families have 5p and 3p strands with different nucleotide (nt) chain sizes. In general, mature 5p strands are larger: two miRNAs of 24 nt, 24 miRNAs of 23 nt, 35 miRNAs of 22 nt and three miRNAs of 21 nt. On the other hand, the 3p strands lengths observed are: seven miRNAs of 23 nt, 50 miRNAs of 22 nt, six miRNAs of 21 nt and four miRNAs of 20 nt. Based on the analysis of the 20 miRNA families associated with cervical cancer, 67 3p strands and 65 5p strands are selected suggesting selectivity and specificity mechanisms regulating cell processes like proliferation, apoptosis, migration, invasion, metabolism and Warburg effect. The insight reviewed here could be used in the miRNA based therapy, diagnosis and prognosis approaches.

LOC100287225, novel long intergenic non-coding RNA, misregulates in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers in the world; therefore, extensive research is needed to find new molecular therapeutic targets and biomarkers. LncRNA (long non-coding RNA), a new class of non-coding RNAs, has a crucial role in the onset and progression of various cancers including colorectal cancer. Research on lncRNA is still at initial stages and underlying molecular mechanisms of the vast majority of lncRNA have remained unclear. LOC100287225 is one of these novel lncRNAs (long intergenic non-coding RNA) located in the long arm of the chromosome 18. The purpose of this study was to determine the expression of LOC100287225 in colorectal tissue, and its misregulation in CRC patients. Quantitative real-time-PCR (qRT-PCR) was used to investigate the LOC100287225 expression in pairs of tumorous and adjacent tumor-free tissues of 39 colorectal cancer patients. Also, the relationship between the clinicopathology and expression of LOC100287225 was determined. QRT-PCR results revealed that not only is LOC100287225 expressed in the intestinal tissue, but has also been misregulated during tumorigenesis. Moreover, LOC100287225 RNA relative expression levels were significantly lower in tumor tissues compared with adjacent tumor-free tissues (P< 0.001). RNA expression level of LOC100287225 did not show significant correlation with clinical characteristics. In conclusion, our study demonstrated that LOC100287225 misregulation could be a potential target for gene therapy in colorectal cancer.

Preliminary evidence for association of genetic variants in pri-miR-34b/c and abnormal miR-34c expression with attention deficit and hyperactivity disorder

Attention deficit and hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder characterized by impairment to sustain attention and inability to control impulses and activity level. The etiology of ADHD is complex, with an estimated heritability of 70-80%. Under the hypothesis that alterations in the processing or target binding of microRNAs (miRNAs) may result in functional alterations predisposing to ADHD, we explored whether common polymorphisms potentially affecting miRNA-mediated regulation are involved in this psychiatric disorder. We performed a comprehensive association study focused on 134 miRNAs in 754 ADHD subjects and 766 controls and found association between the miR-34b/c locus and ADHD. Subsequently, we provided preliminary evidence for overexpression of the miR-34c-3p mature form in peripheral blood mononuclear cells of ADHD subjects. Next, we tested the effect on gene expression of single-nucleotide polymorphisms within the ADHD-associated region and found that rs4938923 in the promoter of the pri-miR-34b/c tags cis expression quantitative trait loci for both miR-34b and miR-34c and has an impact on the expression levels of 681 transcripts in trans, including genes previously associated with ADHD. This gene set was enriched for miR-34b/c binding sites, functional categories related to the central nervous system, such as axon guidance or neuron differentiation, and serotonin biosynthesis and signaling canonical pathways. Our results provide preliminary evidence for the contribution to ADHD of a functional variant in the pri-miR-34b/c promoter, possibly through dysregulation of the expression of mature forms of miR-34b and miR-34c and some target genes. These data highlight the importance of abnormal miRNA function as a potential epigenetic mechanism contributing to ADHD.

H19 non coding RNA-derived miR-675 enhances tumorigenesis and metastasis of breast cancer cells by downregulating c-Cbl and Cbl-b

H19 is a long non-coding RNA precursor of miR-675microRNA. H19 is increasingly described to play key roles in the progression and metastasis of cancers from different tissue origins. We have previously shown that the H19 gene is activated by growth factors and increases breast cancer cell invasion. In this study, we established H19/miR-675 ectopic expression models of MDA-MB-231 breast cancer cells to further investigate the underlying mechanisms of H19 oncogenic action. We showed that overexpression of H19/miR-675 enhanced the aggressive phenotype of breast cancer cells including increased cell proliferation and migration in vitro, and increased tumor growth and metastasis in vivo. Moreover, we identified ubiquitin ligase E3 family (c-Cbl and Cbl-b) as direct targets of miR-675 in breast cancer cells. Using a luciferase assay, we demonstrated that H19, through its microRNA, decreased both c-Cbl and Cbl-b expression in all breast cancer cell lines tested. Thus, by directly binding c-Cbl and Cbl-b mRNA, miR-675 increased the stability and the activation of EGFR and c-Met, leading to sustained activation of Akt and Erk as well as enhanced cell proliferation and migration. Our data describe a novel mechanism of protumoral action of H19 in breast cancer.

A 3'UTR polymorphism marks differential KLRG1 mRNA levels through disruption of a miR-584-5p binding site and associates with pemphigus foliaceus susceptibility

Genetic variations mapping to 3' untranslated regions (3'UTRs) may overlap with microRNA (miRNA) binding sites, therefore potentially interfering with translation inhibition or messenger RNA (mRNA) degradation. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) located within the 3'UTRs of six candidate genes and predicted to interfere with miRNA ligation could account for disease-relevant differential mRNA levels. Focusing on pemphigus foliaceus (PF) - an autoimmune blistering skin condition with unique endemic patterns - we investigated whether nine 3'UTR SNPs from the CD1D, CTLA4, KLRD1, KLRG1, NKG7, and TNFSF13B genes differentially expressed in PF were disease-associated. The heterozygous genotype of the KLRG1 rs1805672 polymorphism was associated with increased predisposition to PF (A/G vs. A/A: P=0.038; OR=1.60), and a trend for augmented susceptibility was observed for carriers of the G allele (P=0.094; OR=1.44). In silico analyses suggested that rs1805672 G allele could disrupt binding of miR-584-5p, and indicated rs1805672 as an expression Quantitative Trait Locus (eQTL), with an effect on KLRG1 gene expression. Dual-luciferase assay showed that miR-584-5p mediated approximately 50% downregulation of the reporter gene's activity through the 3'UTR of KLRG1 harboring rs1805672 A allele (vs. miRNA-negative condition, P=0.006). This silencing relationship was lost after site-directed mutation to G allele (vs. miRNA-negative condition, P=0.391; vs. rs1805672 A allele, P=0.005). Collectively, these results suggest that a disease-associated SNP located within the 3'UTR of KLRG1 directly interferes with miR-584-5p binding, allowing for KLRG1 mRNA differential accumulation, which in turn may contribute to pathogenesis of autoimmune diseases, such as pemphigus.

MicroRNA-184 Modulates Doxorubicin Resistance in Osteosarcoma Cells by Targeting BCL2L1

Background

Early metastasis of osteosarcoma (OS) is highly lethal and responds poorly to drug and radiation therapies. MicroRNAs (miRNAs) are a class of small noncoding RNAs that modulate gene expression at the post-transcriptional level. However, the detailed functions of specific miRNAs are not entirely understood. The aim of the present study was to investigate the role of miR-184 as a mediator of drug resistance in human osteosarcoma.

Material/Methods

qRT-PCR was used to analyze the expression level of miR-184 in OS cell line U-2 OS and MG-63 treated with doxorubicin. MiR-184 agomir or miR-184 antagomir was transferred into cells to regulated miR-184. The target of miR-184 was predicted by TargetScan and confirmed by luciferase reporter assay. Bcl-2-like protein 1 (BCL2L1) expression was detected by Western blot. Cell apoptosis was determined by Annexin V staining and analysis by flow cytometry.

Results

Doxorubicin induced time-dependent expression of miR-184 in OS cell line U-2 OS and MG-63. Luciferase reporter assay identified BCL2L1 as the direct target gene of miR-184. Furthermore, doxorubicin reduced BCL2L1 expression, which was reversed by miR-184 overexpression and further decreased by miR-184 inhibition in OS cells. In addition, miR-184 agomir reduced doxorubicin-induced cell apoptosis, whereas miR-184 antagomir enhanced apoptosis in OS cells, suggesting that up-regulation of miR-184 contributes to chemoresistance of the OS cell line.

Conclusions

Our data show that miR-184 was up-regulated in OS patients treated with doxorubicin therapy and leads to poor response to drug therapy by targeting BCL2L1.

miR-27a and miR-27a* contribute to metastatic properties of osteosarcoma cells

Osteosarcoma (OS) is the most common primary malignant bone tumor in adolescents and young adults. The essential mechanisms underlying osteosarcomagenesis and progression continue to be obscure. MicroRNAs (miRNAs) have far-reaching effects on the cellular biology of development and cancer. We recently reported that unique miRNA signatures associate with the pathogenesis and progression of OS. Of particular interest, we found that higher expression of miR-27a is associated with clinical metastatic disease. We report here that overexpression of miR-27a/miR-27a*, a microRNA pair derived from a single precursor, promotes pulmonary OS metastases formation. By contrast, sequestering miR-27a/miR-27a* by sponge technology suppressed OS cells invasion and metastases formation. miR-27a/miR-27a* directly repressed CBFA2T3 expression among other target genes. We demonstrated that CBFA2T3 is downregulated in majority of OS samples and its over expression significantly attenuated OS metastatic process mediated by miR-27a/miR-27a* underscoring CBFA2T3 functions as a tumor suppressor in OS. These findings establish that miR-27a/miR-27a* pair plays a significant role in OS metastasis and proposes it as a potential diagnostic and therapeutic target in managing OS metastases.

MicroRNA (miRNA) Signaling in the Human CNS in Sporadic Alzheimer's Disease (AD)-Novel and Unique Pathological Features

Of the approximately ~2.65 × 10³ mature microRNAs (miRNAs) so far identified in Homo sapiens, only a surprisingly small but select subset—about 35–40—are highly abundant in the human central nervous system (CNS). This fact alone underscores the extremely high selection pressure for the human CNS to utilize only specific ribonucleotide sequences contained within these single-stranded non-coding RNAs (ncRNAs) for productive miRNA–mRNA interactions and the down-regulation of gene expression. In this article we will: (i) consolidate some of our still evolving ideas concerning the role of miRNAs in the CNS in normal aging and in health, and in sporadic Alzheimer’s disease (AD) and related forms of chronic neurodegeneration; and (ii) highlight certain aspects of the most current work in this research field, with particular emphasis on the findings from our lab of a small pathogenic family of six inducible, pro-inflammatory, NF-κB-regulated miRNAs including miRNA-7, miRNA-9, miRNA-34a, miRNA-125b, miRNA-146a and miRNA-155. This group of six CNS-abundant miRNAs significantly up-regulated in sporadic AD are emerging as what appear to be key mechanistic contributors to the sporadic AD process and can explain much of the neuropathology of this common, age-related inflammatory neurodegeneration of the human CNS.

Dynamic miRNA-mRNA paradigms: New faces of miRNAs

More and more evidences suggested that the flow of genetic information can be spatially and temporally regulated by non-coding RNAs (ncRNAs), such as microRNAs (miRNAs). Although biogenesis and function of miRNAs have been well detailed, elucidation of the dynamic interplays between miRNAs and mRNAs have just begun. Here, we highlighted that the miRNA-mRNA interactions which could take place in different cellular locations. During dynamic interactions, miRNA binding sites included not only 3'UTRs, but also 5'UTRs and CDSs. Under different physiological or pathological conditions, miRNAs could switch from translational inhibition to activation. Dynamic miRNA-mRNA paradigms which suggested a novel tip of the iceberg beneath the gene regulation network will provide clues for function studies of other ncRNAs.

MicroRNA-539 suppresses osteosarcoma cell invasion and migration in vitro and targeting Matrix metallopeptidase-8

MicroRNAs (miRNA) are a class of small, non-coding RNA that involved in different cancer-related processes. Previous studies have been indicated miR-539 as a tumor suppressor during tumorigenesis. However, the role of miR-539 in osteosarcoma is still unclear. In this study, we demonstrate miR-539 was downregulated in osteosarcoma tissues compared to adjacent normal tissue. Functional study suggests miR-539 inhabits the osteosarcoma cell proliferation, invasion and migration. We also identified that MMP8 was a direct target of miR-539 by the luciferase activity assay. These findings provide evidence that miR-539 plays a key role in inhibiting osteosarcoma cell invasion and migration and can regulating MMP8 expression in osteosarcoma cells. These strongly suggest that exogenous miR-539 may have therapeutic value in treating osteosarcoma.

Deregulation of protein translation control, a potential game-changing hypothesis for Parkinson's disease pathogenesis

Protein translation is one of the most fundamental and exquisitely controlled processes in biology, and is energetically demanding. The deregulation of this process is deleterious to cells, as demonstrated by several diseases caused by mutations in protein translation machinery. Emerging evidence now points to a role for protein translation in the pathogenesis of Parkinson's disease (PD); a debilitating neurodegenerative movement disorder. In this paper, we propose a hypothesis that protein translation machinery, PD-associated proteins and PD pathology are connected in a functional network linking cell survival to protein translation control. This hypothesis is a potential game changer in the field of the molecular pathogenesis of PD, with implications for the development of PD diagnostics and disease-modifying therapies.

PTEN ceRNA networks in human cancer

In multiple human cancer types, a close link exists between the expression levels of Phosphatase and Tensin Homolog deleted on chromosome 10 (PTEN) and its oncosuppressive activities. Therefore, an in depth understanding of the molecular mechanisms by which PTEN expression is modulated is crucial in order to achieve a comprehensive knowledge of its biological roles. In recent years, the competition between PTEN mRNA and other RNAs for shared microRNA molecules has emerged as one such mechanism and has brought into focus the coding-independent activities of PTEN and other mRNAs. In this review article, we examine the competing endogenous RNA (ceRNA) partners of PTEN that have been identified so far. We also discuss how PTEN-centered ceRNA networks can contribute to a deeper understanding of PTEN function and tumorigenesis.