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Genomic analyses reveal miR-137 broad impact on genes associated with malignant transformation and neuronal differentiation in glioblastoma cells

ABSTRACT: miR-137 plays critical roles in the nervous system and tumor development. An increase in its expression is required for neuronal differentiation while its reduction is implicated in gliomagenesis. To evaluate the potential of miR-137 in glioblastoma therapy, we conducted genome-wide target mapping in glioblastoma cells by measuring levels of associations between PABP and mRNAs in cells transfected with miR-137 mimics vs. controls via RIPSeq. Impact on mRNA levels was also measured by RNASeq. By combining the results of both experimental approaches, 1468 genes were determined to be negatively impacted by miR-137; among them, 595 (40%) contain miR-137 predicted sites. The most relevant targets include oncogenic proteins and players in neurogenesis like c-KIT, YBX1, AKT2, CDC42, CDK6 and TGFβ2. Interestingly, we observed that several identified miR-137 targets are also predicted to be regulated by miR-124, miR-128 and miR-7, which are equally implicated in neuronal differentiation and gliomagenesis. We suggest that the concomitant increase of these four miRNAs in neuronal stem cells or their repression in tumor cells could produce a robust regulatory effect with major consequences to neuronal differentiation and tumorigenesis. Identification of genes affected by miR137 transfection via RIP-Seq and RNA-Seq in U251 and U343 cells

ORGANISM(S): Homo sapiens

SUBMITTER: Tamim S

PROVIDER: S-ECPF-GEOD-53220 | biostudies-other | 2014

REPOSITORIES: biostudies-other

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Project description:BackgroundClostridium botulinum is a diverse group of bacteria characterized by the production of botulinum neurotoxin. Botulinum neurotoxins are classified into serotypes (BoNT/A-G), which are produced by six species/Groups of Clostridia, but the genetic background of the bacteria remains poorly understood. The purpose of this study was to use comparative genomics to provide insights into the genetic diversity and evolutionary history of bacteria that produce the potent botulinum neurotoxin.ResultsComparative genomic analyses of over 170 Clostridia genomes, including our draft genome assemblies for 59 newly sequenced Clostridia strains from six continents and publicly available genomic data, provided in-depth insights into the diversity and distribution of BoNT-producing bacteria. These newly sequenced strains included Group I and II strains that express BoNT/A,/B,/E, or/F as well as bivalent strains. BoNT-producing Clostridia and closely related Clostridia species were delineated with a variety of methods including 16S rRNA gene, concatenated marker genes, core genome and concatenated multi-locus sequencing typing (MLST) gene phylogenies that related whole genome sequenced strains to publicly available strains and sequence types. These analyses illustrated the phylogenetic diversity in each Group and the diversity of genomic backgrounds that express the same toxin type or subtype. Comparisons of the botulinum neurotoxin genes did not identify novel toxin types or variants.ConclusionsThis study represents one of the most comprehensive analyses of whole genome sequence data for Group I and II BoNT-producing strains. Read data and draft genome assemblies generated for 59 isolates will be a resource to the research community. Core genome phylogenies proved to be a powerful tool for differentiating BoNT-producing strains and can provide a framework for the study of these bacteria. Comparative genomic analyses of Clostridia species illustrate the diversity of botulinum-neurotoxin-producing strains and the plasticity of the genomic backgrounds in which bont genes are found.

Project description:GBM (Glioblastoma multiform) is the most malignant tumor type of the central nervous system and has poor diagnostic and clinical outcomes. LncRNAs (Long non-coding RNAs) have been reported to participate in multiple biological and pathological processes, but their underlying mechanism remains poorly understood. Here, we aimed to explore the role of the lncRNA HAS2-AS1 (HAS2 antisense RNA 1) in GBM. GSE103227 was analyzed, and qRT-PCR was performed to measure the expression of HAS2-AS1 in GBM. FISH (Fluorescence in situ hybridization) was performed to verify the localization of HAS2-AS1. The interaction between HAS2-AS1 and miR-137 (microRNA-137) was predicted by LncBook and miRcode followed by dual-luciferase reporter assays, and the relationships among HAS2-AS1, miR-137 and LSD1 (lysine-specific demethylase 1) were assessed by WB (western blot) and qRT-PCR. Colony formation and CCK-8 (cell counting kit-8) assays were performed as functional tests. In vivo, nude mice were used to confirm the function of HAS2-AS1. HAS2-AS1 expression was upregulated in GBM cell lines, and HAS2-AS1 was localized mainly in the cytoplasm. In vitro, high HAS2-AS1 expression promoted proliferation, and knockdown of HAS2-AS1 significantly inhibited proliferation. Furthermore, HAS2-AS1 functioned as a ceRNA (competing endogenous RNA) of miR-137, leading to the disinhibition of its downstream target LSD1. The miR-137 level was downregulated by HAS2-AS1 overexpression and upregulated by HAS2-AS1 knockdown. In a subsequent study, LSD1 expression was negatively regulated by miR-137, while miR-137 reversed the LSD1 expression levels caused by HAS2-AS1. These results were further supported by the nude mouse tumorigenesis experiment; compared with xenografts with high HAS2-AS1 expression, the group with low levels of HAS2-AS1 exhibited suppressed proliferation and better survival. We conclude that lncRNA HAS2-AS1 promotes proliferation by functioning as a miR-137 decoy to increase LSD1 levels and thus might be a possible biomarker for GBM.

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Genomic analyses reveal miR-137 broad impact on genes associated with malignant transformation and neuronal differentiation in glioblastoma cells

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