Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 54
Filtrar
1.
RNA Biol ; 20(1): 311-322, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-37294214

RESUMO

The exon junction complex (EJC) plays key roles throughout the lifespan of RNA and is particularly relevant in the nervous system. We investigated the roles of two EJC members, the paralogs MAGOH and MAGOHB, with respect to brain tumour development. High MAGOH/MAGOHB expression was observed in 14 tumour types; glioblastoma (GBM) showed the greatest difference compared to normal tissue. Increased MAGOH/MAGOHB expression was associated with poor prognosis in glioma patients, while knockdown of MAGOH/MAGOHB affected different cancer phenotypes. Reduced MAGOH/MAGOHB expression in GBM cells caused alterations in the splicing profile, including re-splicing and skipping of multiple exons. The binding profiles of EJC proteins indicated that exons affected by MAGOH/MAGOHB knockdown accumulated fewer complexes on average, providing a possible explanation for their sensitivity to MAGOH/MAGOHB knockdown. Transcripts (genes) showing alterations in the splicing profile are mainly implicated in cell division, cell cycle, splicing, and translation. We propose that high MAGOH/MAGOHB levels are required to safeguard the splicing of genes in high demand in scenarios requiring increased cell proliferation (brain development and GBM growth), ensuring efficient cell division, cell cycle regulation, and gene expression (splicing and translation). Since differentiated neuronal cells do not require increased MAGOH/MAGOHB expression, targeting these paralogs is a potential option for treating GBM.


Assuntos
Genes cdc , Glioblastoma , Humanos , Splicing de RNA , Divisão Celular , Núcleo Celular/metabolismo , Glioblastoma/metabolismo , Proteínas Nucleares/metabolismo
2.
RNA ; 25(7): 768-782, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31004009

RESUMO

RNA-binding proteins (RBPs) and miRNAs are critical gene expression regulators that interact with one another in cooperative and antagonistic fashions. We identified Musashi1 (Msi1) and miR-137 as regulators of a molecular switch between self-renewal and differentiation. Msi1 and miR-137 have opposite expression patterns and functions, and Msi1 is repressed by miR-137. Msi1 is a stem-cell protein implicated in self-renewal while miR-137 functions as a proneuronal differentiation miRNA. In gliomas, miR-137 functions as a tumor suppressor while Msi1 is a prooncogenic factor. We suggest that the balance between Msi1 and miR-137 is a key determinant in cell fate decisions and disruption of this balance could contribute to neurodegenerative diseases and glioma development. Genomic analyses revealed that Msi1 and miR-137 share 141 target genes associated with differentiation, development, and morphogenesis. Initial results pointed out that these two regulators have an opposite impact on the expression of their target genes. Therefore, we propose an antagonistic model in which this network of shared targets could be either repressed by miR-137 or activated by Msi1, leading to different outcomes (self-renewal, proliferation, tumorigenesis).


Assuntos
Diferenciação Celular , Transformação Celular Neoplásica/patologia , Regulação Neoplásica da Expressão Gênica , Glioblastoma/patologia , MicroRNAs/genética , Proteínas do Tecido Nervoso/metabolismo , Neurogênese , Proteínas de Ligação a RNA/metabolismo , Animais , Proliferação de Células , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Glioblastoma/genética , Glioblastoma/metabolismo , Humanos , Proteínas do Tecido Nervoso/genética , Proteínas de Ligação a RNA/genética , Transdução de Sinais , Células Tumorais Cultivadas
3.
Nature ; 499(7457): 172-7, 2013 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-23846655

RESUMO

RNA-binding proteins are key regulators of gene expression, yet only a small fraction have been functionally characterized. Here we report a systematic analysis of the RNA motifs recognized by RNA-binding proteins, encompassing 205 distinct genes from 24 diverse eukaryotes. The sequence specificities of RNA-binding proteins display deep evolutionary conservation, and the recognition preferences for a large fraction of metazoan RNA-binding proteins can thus be inferred from their RNA-binding domain sequence. The motifs that we identify in vitro correlate well with in vivo RNA-binding data. Moreover, we can associate them with distinct functional roles in diverse types of post-transcriptional regulation, enabling new insights into the functions of RNA-binding proteins both in normal physiology and in human disease. These data provide an unprecedented overview of RNA-binding proteins and their targets, and constitute an invaluable resource for determining post-transcriptional regulatory mechanisms in eukaryotes.


Assuntos
Regulação da Expressão Gênica/genética , Motivos de Nucleotídeos/genética , Proteínas de Ligação a RNA/metabolismo , Transtorno Autístico/genética , Sequência de Bases , Sítios de Ligação/genética , Sequência Conservada/genética , Células Eucarióticas/metabolismo , Humanos , Dados de Sequência Molecular , Estrutura Terciária de Proteína/genética , Fatores de Processamento de RNA , Estabilidade de RNA/genética , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/genética
4.
Adv Exp Med Biol ; 1157: 29-39, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31342436

RESUMO

Post-transcriptional regulation of gene expression is fundamental for all forms of life, as it critically contributes to the composition and quantity of a cell's proteome. These processes encompass splicing, polyadenylation, mRNA decay, mRNA editing and modification and translation and are modulated by a variety of RNA-binding proteins (RBPs). Alterations affecting RBP expression and activity contribute to the development of different types of cancer. In this chapter, we discuss current research shedding light on the role of different RBPs in gliomas. These studies place RBPs as modulators of critical signaling pathways, establish their relevance as prognostic markers and open doors for new therapeutic strategies.


Assuntos
Glioma , Proteínas de Ligação a RNA , Glioma/fisiopatologia , Humanos , Poliadenilação , Splicing de RNA , Estabilidade de RNA , Proteínas de Ligação a RNA/metabolismo
5.
Bioinformatics ; 33(11): 1735-1737, 2017 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-28158331

RESUMO

MOTIVATION: Global analysis of translation regulation has recently been enabled by the development of Ribosome Profiling, or Ribo-seq, technology. This approach provides maps of ribosome activity for each expressed gene in a given biological sample. Measurements of translation efficiency are generated when Ribo-seq data is analyzed in combination with matched RNA-seq gene expression profiles. Existing computational methods for identifying genes with differential translation across samples are based on sound principles, but require users to choose between accuracy and speed. RESULTS: We present Riborex, a computational tool for mapping genome-wide differences in translation efficiency. Riborex shares a similar mathematical structure with existing methods, but has a simplified implementation. Riborex directly leverages established RNA-seq analysis frameworks for all parameter estimation, providing users with a choice among robust engines for these computations. The result is a method that is dramatically faster than available methods without sacrificing accuracy. AVAILABILITY AND IMPLEMENTATION: https://github.com/smithlabcode/riborex. CONTACT: andrewds@usc.edu. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.


Assuntos
Biossíntese de Proteínas , Ribossomos/metabolismo , Análise de Sequência de RNA/métodos , Software , Transcriptoma , Animais , Biologia Computacional/métodos , Humanos , Camundongos
6.
RNA Biol ; 15(11): 1420-1432, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30362859

RESUMO

RNA binding proteins have emerged as critical oncogenic factors and potential targets in cancer therapy. In this study, we evaluated Musashi1 (Msi1) targeting as a strategy to treat glioblastoma (GBM); the most aggressive brain tumor type. Msi1 expression levels are often high in GBMs and other tumor types and correlate with poor clinical outcome. Moreover, Msi1 has been implicated in chemo- and radio-resistance. Msi1 modulates a range of cancer relevant processes and pathways and regulates the expression of stem cell markers and oncogenic factors via mRNA translation/stability. To identify Msi1 inhibitors capable of blocking its RNA binding function, we performed a ~ 25,000 compound fluorescence polarization screen. NMR and LSPR were used to confirm direct interaction between Msi1 and luteolin, the leading compound. Luteolin displayed strong interaction with Msi1 RNA binding domain 1 (RBD1). As a likely consequence of this interaction, we observed via western and luciferase assays that luteolin treatment diminished Msi1 positive impact on the expression of pro-oncogenic target genes. We tested the effect of luteolin treatment on GBM cells and showed that it reduced proliferation, cell viability, colony formation, migration and invasion of U251 and U343 GBM cells. Luteolin also decreased the proliferation of patient-derived glioma initiating cells (GICs) and tumor-organoids but did not affect normal astrocytes. Finally, we demonstrated the value of combined treatments with luteolin and olaparib (PARP inhibitor) or ionizing radiation (IR). Our results show that luteolin functions as an inhibitor of Msi1 and demonstrates its potential use in GBM therapy.


Assuntos
Glioblastoma/tratamento farmacológico , Luteolina/farmacologia , Proteínas do Tecido Nervoso/antagonistas & inibidores , Proteínas de Ligação a RNA/química , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Terapia Combinada , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Glioblastoma/genética , Glioblastoma/patologia , Glioblastoma/radioterapia , Humanos , Luteolina/química , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/genética , Fenótipo , Ftalazinas/administração & dosagem , Piperazinas/administração & dosagem , RNA/química , RNA/genética , Proteínas de Ligação a RNA/antagonistas & inibidores , Proteínas de Ligação a RNA/genética , Radiação Ionizante , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/farmacologia
7.
Am J Pathol ; 186(9): 2271-8, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27470713

RESUMO

The conserved RNA-binding protein Musashi1 (MSI1) has been characterized as a stem cell marker, controlling the balance between self-renewal and differentiation and as a key oncogenic factor in numerous solid tumors, including glioblastoma. To explore the potential use of MSI1 targeting in therapy, we studied MSI1 in the context of radiation sensitivity. Knockdown of MSI1 led to a decrease in cell survival and an increase in DNA damage compared to control in cells treated with ionizing radiation. We subsequently examined mechanisms of double-strand break repair and found that loss of MSI1 reduces the frequency of nonhomologous end-joining. This phenomenon could be attributed to the decreased expression of DNA-protein kinase catalytic subunit, which we have previously identified as a target of MSI1. Collectively, our results suggest a role for MSI1 in double-strand break repair and that its inhibition may enhance the effect of radiotherapy.


Assuntos
Reparo do DNA/fisiologia , Glioblastoma/patologia , Proteínas do Tecido Nervoso/metabolismo , Polinucleotídeo 5'-Hidroxiquinase/metabolismo , Proteínas de Ligação a RNA/metabolismo , Tolerância a Radiação/fisiologia , Domínio Catalítico/fisiologia , Linhagem Celular Tumoral , Ensaio Cometa , Quebras de DNA de Cadeia Dupla/efeitos da radiação , DNA Catalítico , Imunofluorescência , Humanos , Immunoblotting , Reação em Cadeia da Polimerase
8.
Stem Cells ; 34(1): 220-32, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26369286

RESUMO

The ventricular-subventricular zone harbors neural stem cells (NSCs) that can differentiate into neurons, astrocytes, and oligodendrocytes. This process requires loss of stem cell properties and gain of characteristics associated with differentiated cells. miRNAs function as important drivers of this transition; miR-124, -128, and -137 are among the most relevant ones and have been shown to share commonalities and act as proneurogenic regulators. We conducted biological and genomic analyses to dissect their target repertoire during neurogenesis and tested the hypothesis that they act cooperatively to promote differentiation. To map their target genes, we transfected NSCs with antagomiRs and analyzed differences in their mRNA profile throughout differentiation with respect to controls. This strategy led to the identification of 910 targets for miR-124, 216 for miR-128, and 652 for miR-137. The target sets show extensive overlap. Inspection by gene ontology and network analysis indicated that transcription factors are a major component of these miRNAs target sets. Moreover, several of these transcription factors form a highly interconnected network. Sp1 was determined to be the main node of this network and was further investigated. Our data suggest that miR-124, -128, and -137 act synergistically to regulate Sp1 expression. Sp1 levels are dramatically reduced as cells differentiate and silencing of its expression reduced neuronal production and affected NSC viability and proliferation. In summary, our results show that miRNAs can act cooperatively and synergistically to regulate complex biological processes like neurogenesis and that transcription factors are heavily targeted to branch out their regulatory effect.


Assuntos
Diferenciação Celular/genética , Redes Reguladoras de Genes , MicroRNAs/genética , MicroRNAs/metabolismo , Neurônios/citologia , Neurônios/metabolismo , Fator de Transcrição Sp1/metabolismo , Animais , Proliferação de Células , Autorrenovação Celular , Regulação da Expressão Gênica , Genoma , Humanos , Camundongos , Células-Tronco Neurais/citologia , Oligonucleotídeos Antissenso/metabolismo , Análise de Sequência de RNA , Transfecção
9.
Nucleic Acids Res ; 43(1): 95-103, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25505146

RESUMO

High-throughput protein-RNA interaction data generated by CLIP-seq has provided an unprecedented depth of access to the activities of RNA-binding proteins (RBPs), the key players in co- and post-transcriptional regulation of gene expression. Motif discovery forms part of the necessary follow-up data analysis for CLIP-seq, both to refine the exact locations of RBP binding sites, and to characterize them. The specific properties of RBP binding sites, and the CLIP-seq methods, provide additional information not usually present in the classic motif discovery problem: the binding site structure, and cross-linking induced events in reads. We show that CLIP-seq data contains clear secondary structure signals, as well as technology- and RBP-specific cross-link signals. We introduce Zagros, a motif discovery algorithm specifically designed to leverage this information and explore its impact on the quality of recovered motifs. Our results indicate that using both secondary structure and cross-link modifications can greatly improve motif discovery on CLIP-seq data. Further, the motifs we recover provide insight into the balance between sequence- and structure-specificity struck by RBP binding.


Assuntos
Algoritmos , Proteínas de Ligação a RNA/metabolismo , RNA/química , Regiões 3' não Traduzidas , Sítios de Ligação , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Imunoprecipitação , Modelos Estatísticos , Conformação de Ácido Nucleico , Motivos de Nucleotídeos , RNA/metabolismo , Análise de Sequência de RNA/métodos
10.
RNA Biol ; 13(4): 400-11, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26760575

RESUMO

hnRNPs are polyvalent RNA binding proteins that have been implicated in a range of regulatory roles including splicing, mRNA decay, translation, and miRNA metabolism. A variety of genome wide studies have taken advantage of methods like CLIP and RIP to identify the targets and binding sites of RNA binding proteins. However, due to the complex nature of RNA-binding proteins, these studies are incomplete without assays that characterize the impact of RBP binding on mRNA target expression. Here we used a suite of high-throughput approaches (RIP-Seq, iCLIP, RNA-Seq and shotgun proteomics) to provide a comprehensive view of hnRNP H1s ensemble of targets and its role in splicing, mRNA decay, and translation. The combination of RIP-Seq and iCLIP allowed us to identify a set of 1,086 high confidence target transcripts. Binding site motif analysis of these targets suggests the TGGG tetramer as a prevalent component of hnRNP H1 binding motif, with particular enrichment around intronic hnRNP H1 sites. Our analysis of the target transcripts and binding sites indicates that hnRNP H1s involvement in splicing is 2-fold: it directly affects a substantial number of splicing events, but also regulates the expression of major components of the splicing machinery and other RBPs with known roles in splicing regulation. The identified mRNA targets displayed function enrichment in MAPK signaling and ubiquitin mediated proteolysis, which might be main routes by which hnRNP H1 promotes tumorigenesis.


Assuntos
Ribonucleoproteínas Nucleares Heterogêneas Grupo F-H/genética , Sequenciamento de Nucleotídeos em Larga Escala , Sítios de Ligação , Células HeLa , Ribonucleoproteínas Nucleares Heterogêneas Grupo F-H/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas Grupo F-H/fisiologia , Humanos , Splicing de RNA
11.
Proc Natl Acad Sci U S A ; 108(22): 9232-7, 2011 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-21576456

RESUMO

Cellular imbalances of cholesterol and fatty acid metabolism result in pathological processes, including atherosclerosis and metabolic syndrome. Recent work from our group and others has shown that the intronic microRNAs hsa-miR-33a and hsa-miR-33b are located within the sterol regulatory element-binding protein-2 and -1 genes, respectively, and regulate cholesterol homeostasis in concert with their host genes. Here, we show that miR-33a and -b also regulate genes involved in fatty acid metabolism and insulin signaling. miR-33a and -b target key enzymes involved in the regulation of fatty acid oxidation, including carnitine O-octaniltransferase, carnitine palmitoyltransferase 1A, hydroxyacyl-CoA-dehydrogenase, Sirtuin 6 (SIRT6), and AMP kinase subunit-α. Moreover, miR-33a and -b also target the insulin receptor substrate 2, an essential component of the insulin-signaling pathway in the liver. Overexpression of miR-33a and -b reduces both fatty acid oxidation and insulin signaling in hepatic cell lines, whereas inhibition of endogenous miR-33a and -b increases these two metabolic pathways. Together, these data establish that miR-33a and -b regulate pathways controlling three of the risk factors of metabolic syndrome, namely levels of HDL, triglycerides, and insulin signaling, and suggest that inhibitors of miR-33a and -b may be useful in the treatment of this growing health concern.


Assuntos
Ácidos Graxos/metabolismo , Insulina/metabolismo , MicroRNAs/biossíntese , Animais , Doenças Cardiovasculares/metabolismo , Colesterol/metabolismo , Citoplasma/metabolismo , Drosophila melanogaster/metabolismo , Homeostase , Humanos , Imuno-Histoquímica/métodos , Lipídeos/química , Fosforilação , Processamento Pós-Transcricional do RNA , Transdução de Sinais
12.
Cell Death Dis ; 15(5): 306, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38693105

RESUMO

Colorectal cancers (CRCs) are highly heterogeneous and show a hierarchical organization, with cancer stem cells (CSCs) responsible for tumor development, maintenance, and drug resistance. Our previous studies showed the importance of thyroid hormone-dependent signaling on intestinal tumor development and progression through action on stem cells. These results have a translational value, given that the thyroid hormone nuclear receptor TRα1 is upregulated in human CRCs, including in the molecular subtypes associated with CSC features. We used an established spheroid model generated from the human colon adenocarcinoma cell line Caco2 to study the effects of T3 and TRα1 on spheroid formation, growth, and response to conventional chemotherapies. Our results show that T3 treatment and/or increased TRα1 expression in spheroids impaired the response to FOLFIRI and conferred a survival advantage. This was achieved by stimulating drug detoxification pathways and increasing ALDH1A1-expressing cells, including CSCs, within spheroids. These results suggest that clinical evaluation of the thyroid axis and assessing TRα1 levels in CRCs could help to select optimal therapeutic regimens for patients with CRC. Proposed mechanism of action of T3/TRα1 in colon cancer spheroids. In the control condition, TRα1 participates in maintaining homeostatic cell conditions. The presence of T3 in the culture medium activates TRα1 action on target genes, including the drug efflux pumps ABCG2 and ABCB1. In the case of chemotherapy FOLFIRI, the increased expression of ABC transcripts and proteins induced by T3 treatment is responsible for the augmented efflux of 5-FU and Irinotecan from the cancer cells. Taken together, these mechanisms contribute to the decreased efficacy of the chemotherapy and allow cells to escape the treatment. Created with BioRender.com .


Assuntos
Camptotecina/análogos & derivados , Neoplasias do Colo , Fluoruracila , Células-Tronco Neoplásicas , Esferoides Celulares , Receptores alfa dos Hormônios Tireóideos , Tri-Iodotironina , Humanos , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/patologia , Fluoruracila/farmacologia , Fluoruracila/uso terapêutico , Receptores alfa dos Hormônios Tireóideos/metabolismo , Receptores alfa dos Hormônios Tireóideos/genética , Células CACO-2 , Neoplasias do Colo/metabolismo , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/patologia , Neoplasias do Colo/genética , Esferoides Celulares/efeitos dos fármacos , Esferoides Celulares/metabolismo , Esferoides Celulares/patologia , Tri-Iodotironina/farmacologia , Leucovorina/farmacologia , Leucovorina/uso terapêutico , Camptotecina/farmacologia , Camptotecina/uso terapêutico , Fenótipo , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Família Aldeído Desidrogenase 1/metabolismo , Família Aldeído Desidrogenase 1/genética , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Retinal Desidrogenase/metabolismo , Retinal Desidrogenase/genética , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética
13.
bioRxiv ; 2024 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-38585848

RESUMO

RNA binding proteins (RBPs) containing intrinsically disordered regions (IDRs) are present in diverse molecular complexes where they function as dynamic regulators. Their characteristics promote liquid-liquid phase separation (LLPS) and the formation of membraneless organelles such as stress granules and nucleoli. IDR-RBPs are particularly relevant in the nervous system and their dysfunction is associated with neurodegenerative diseases and brain tumor development. Serpine1 mRNA-binding protein 1 (SERBP1) is a unique member of this group, being mostly disordered and lacking canonical RNA-binding domains. We defined SERBP1's interactome, uncovered novel roles in splicing, cell division and ribosomal biogenesis, and showed its participation in pathological stress granules and Tau aggregates in Alzheimer's brains. SERBP1 preferentially interacts with other G-quadruplex (G4) binders, implicated in different stages of gene expression, suggesting that G4 binding is a critical component of SERBP1 function in different settings. Similarly, we identified important associations between SERBP1 and PARP1/polyADP-ribosylation (PARylation). SERBP1 interacts with PARP1 and its associated factors and influences PARylation. Moreover, protein complexes in which SERBP1 participates contain mostly PARylated proteins and PAR binders. Based on these results, we propose a feedback regulatory model in which SERBP1 influences PARP1 function and PARylation, while PARylation modulates SERBP1 functions and participation in regulatory complexes.

14.
Bioinformatics ; 28(23): 3013-20, 2012 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-23024010

RESUMO

MOTIVATION: Post-transcriptional and co-transcriptional regulation is a crucial link between genotype and phenotype. The central players are the RNA-binding proteins, and experimental technologies [such as cross-linking with immunoprecipitation- (CLIP-) and RIP-seq] for probing their activities have advanced rapidly over the course of the past decade. Statistically robust, flexible computational methods for binding site identification from high-throughput immunoprecipitation assays are largely lacking however. RESULTS: We introduce a method for site identification which provides four key advantages over previous methods: (i) it can be applied on all variations of CLIP and RIP-seq technologies, (ii) it accurately models the underlying read-count distributions, (iii) it allows external covariates, such as transcript abundance (which we demonstrate is highly correlated with read count) to inform the site identification process and (iv) it allows for direct comparison of site usage across cell types or conditions. AVAILABILITY AND IMPLEMENTATION: We have implemented our method in a software tool called Piranha. Source code and binaries, licensed under the GNU General Public License (version 3) are freely available for download from http://smithlab.usc.edu. CONTACT: andrewds@usc.edu SUPPLEMENTARY INFORMATION: Supplementary data available at Bioinformatics online.


Assuntos
Análise de Sequência de RNA/métodos , Software , Sequência de Bases , Sítios de Ligação , Biologia Computacional/métodos , Células HEK293 , Células HeLa , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , RNA/genética , Proteínas de Ligação a RNA/genética
15.
Am J Pathol ; 181(5): 1762-72, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22985791

RESUMO

Musashi1 (Msi1) is a highly conserved RNA-binding protein that is required during the development of the nervous system. Msi1 has been characterized as a stem cell marker, controlling the balance between self-renewal and differentiation, and has also been implicated in tumorigenesis, being highly expressed in multiple tumor types. We analyzed Msi1 expression in a large cohort of medulloblastoma samples and found that Msi1 is highly expressed in tumor tissue compared with normal cerebellum. Notably, high Msi1 expression levels proved to be a sign of poor prognosis. Msi1 expression was determined to be particularly high in molecular subgroups 3 and 4 of medulloblastoma. We determined that Msi1 is required for tumorigenesis because inhibition of Msi1 expression by small-interfering RNAs reduced the growth of Daoy medulloblastoma cells in xenografts. To characterize the participation of Msi1 in medulloblastoma, we conducted different high-throughput analyses. Ribonucleoprotein immunoprecipitation followed by microarray analysis (RIP-chip) was used to identify mRNA species preferentially associated with Msi1 protein in Daoy cells. We also used cluster analysis to identify genes with similar or opposite expression patterns to Msi1 in our medulloblastoma cohort. A network study identified RAC1, CTGF, SDCBP, SRC, PRL, and SHC1 as major nodes of an Msi1-associated network. Our results suggest that Msi1 functions as a regulator of multiple processes in medulloblastoma formation and could become an important therapeutic target.


Assuntos
Neoplasias Cerebelares/genética , Neoplasias Cerebelares/patologia , Redes Reguladoras de Genes/genética , Genes Neoplásicos/genética , Meduloblastoma/genética , Meduloblastoma/patologia , Proteínas do Tecido Nervoso/metabolismo , Proteínas de Ligação a RNA/metabolismo , Animais , Sequência de Bases , Linhagem Celular Tumoral , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Genoma Humano/genética , Células HEK293 , Humanos , Imunoprecipitação , Masculino , Camundongos , Camundongos Nus , Dados de Sequência Molecular , Proteínas do Tecido Nervoso/genética , Análise de Sequência com Séries de Oligonucleotídeos , Prognóstico , Biossíntese de Proteínas/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/genética , Indução de Remissão , Ensaios Antitumorais Modelo de Xenoenxerto
16.
Neuro Oncol ; 25(3): 459-470, 2023 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-35862252

RESUMO

BACKGROUND: The loss of neurogenic tumor suppressor microRNAs miR-124, miR-128, and miR-137 is associated with glioblastoma's undifferentiated state. Most of their impact comes via the repression of a network of oncogenic transcription factors. We conducted a high-throughput functional siRNA screen in glioblastoma cells and identify E74 like ETS transcription factor 4 (ELF4) as the leading contributor to oncogenic phenotypes. METHODS: In vitro and in vivo assays were used to assess ELF4 impact on cancer phenotypes. We characterized ELF4's mechanism of action via genomic and lipidomic analyses. A MAPK reporter assay verified ELF4's impact on MAPK signaling, and qRT-PCR and western blotting were used to corroborate ELF4 regulatory role on most relevant target genes. RESULTS: ELF4 knockdown resulted in significant proliferation delay and apoptosis in GBM cells and long-term growth delay and morphological changes in glioma stem cells (GSCs). Transcriptomic analyses revealed that ELF4 controls two interlinked pathways: 1) Receptor tyrosine kinase signaling and 2) Lipid dynamics. ELF4 modulation directly affected receptor tyrosine kinase (RTK) signaling, as mitogen-activated protein kinase (MAPK) activity was dependent upon ELF4 levels. Furthermore, shotgun lipidomics revealed that ELF4 depletion disrupted several phospholipid classes, highlighting ELF4's importance in lipid homeostasis. CONCLUSIONS: We found that ELF4 is critical for the GBM cell identity by controlling genes of two dependent pathways: RTK signaling (SRC, PTK2B, and TNK2) and lipid dynamics (LRP1, APOE, ABCA7, PLA2G6, and PITPNM2). Our data suggest that targeting these two pathways simultaneously may be therapeutically beneficial to GBM patients.


Assuntos
Neoplasias Encefálicas , Glioblastoma , MicroRNAs , Humanos , Fatores de Transcrição/genética , Glioblastoma/patologia , MicroRNAs/genética , Receptores Proteína Tirosina Quinases/genética , Regulação Neoplásica da Expressão Gênica , Lipídeos , Proliferação de Células , Linhagem Celular Tumoral , Neoplasias Encefálicas/patologia , Proteínas de Ligação a DNA/genética , Proteínas Tirosina Quinases/metabolismo
17.
J Biol Chem ; 286(43): 37063-6, 2011 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-21890634

RESUMO

The ubiquitously expressed RNA-binding protein Hu antigen R (HuR) or ELAVL1 is implicated in a variety of biological processes as well as being linked with a number of diseases, including cancer. Despite a great deal of prior investigation into HuR, there is still much to learn about its function. We take an important step in this direction by conducting cross-linking and immunoprecipitation and RNA sequencing experiments followed by an extensive computational analysis to determine the characteristics of the HuR binding site and impact on the transcriptome. We reveal that HuR targets predominantly uracil-rich single-stranded stretches of varying size, with a strong conservation of structure and sequence composition. Despite the fact that HuR sites are observed in intronic regions, our data do not support a role for HuR in regulating splicing. HuR sites in 3'-UTRs overlap extensively with predicted microRNA target sites, suggesting interplay between the functions of HuR and microRNAs. Network analysis showed that identified targets containing HuR binding sites in the 3' UTR are highly interconnected.


Assuntos
Regiões 3' não Traduzidas/fisiologia , Proteínas ELAV/metabolismo , MicroRNAs/metabolismo , Elementos de Resposta/fisiologia , Proteínas ELAV/genética , Genômica/métodos , Células HeLa , Humanos , MicroRNAs/genética
18.
J Biol Chem ; 286(20): 18066-78, 2011 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-21402708

RESUMO

MicroRNAs function as important regulators of gene expression and are commonly linked to development, differentiation, and diseases such as cancer. To better understand their roles in various biological processes, identification of genes targeted by microRNAs is necessary. Although prediction tools have significantly helped with this task, experimental approaches are ultimately required for extensive target search and validation. We employed two independent yet complementary high throughput approaches to map a large set of mRNAs regulated by miR-122, a liver-specific microRNA implicated in regulation of fatty acid and cholesterol metabolism, hepatitis C infection, and hepatocellular carcinoma. The combination of luciferase reporter-based screening and shotgun proteomics resulted in the identification of 260 proteins significantly down-regulated in response to miR-122 in at least one method, 113 of which contain predicted miR-122 target sites. These proteins are enriched for functions associated with the cell cycle, differentiation, proliferation, and apoptosis. Among these miR-122-sensitive proteins, we identified a large group with strong connections to liver metabolism, diseases, and hepatocellular carcinoma. Additional analyses, including examination of consensus binding motifs for both miR-122 and target sequences, provide further insight into miR-122 function.


Assuntos
Carcinoma Hepatocelular/metabolismo , Genes Neoplásicos , Neoplasias Hepáticas/metabolismo , MicroRNAs/metabolismo , Proteínas de Neoplasias/biossíntese , RNA Neoplásico/metabolismo , Carcinoma Hepatocelular/genética , Linhagem Celular , Humanos , Neoplasias Hepáticas/genética , MicroRNAs/genética , Proteínas de Neoplasias/genética , RNA Neoplásico/genética
19.
Arterioscler Thromb Vasc Biol ; 31(11): 2595-606, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21885851

RESUMO

OBJECTIVE: MicroRNAs play key roles in modulating a variety of cellular processes by posttranscriptional regulation of their target genes. Vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR2), and fibroblast growth factor receptor-1 (FGFR1) were identified by bioinformatic approaches and subsequently validated as targets of microRNA (miR)-16 and miR-424 in endothelial cells (ECs). METHODS AND RESULTS: Mimetics of these microRNAs reduced VEGF, VEGFR2, and FGFR1 expression, whereas specific antagonists enhanced their expression. Expression of mature miR-16 and miR-424 was upregulated on VEGF or basic fibroblast growth factor (bFGF) treatment. This upregulation was accompanied by a parallel increase in primary transcript (pri-miR)-16-1 and pri-miR-16-2 but not in pri-miR-424 levels, indicating a VEGF/bFGF-dependent transcriptional and posttranscriptional regulation of miR-16 and miR-424, respectively. Reduced expression of VEGFR2 and FGFR1 by miR-16 or miR-424 overexpression regulated VEGF and bFGF signaling through these receptors, thereby affecting the activity of downstream components of the pathways. Functionally, miR-16 or miR-424 overexpression reduced proliferation, migration, and cord formation of ECs in vitro, and lentiviral overexpression of miR-16 reduced the ability of ECs to form blood vessels in vivo. CONCLUSION: We conclude that these miRNAs fine-tune the expression of selected endothelial angiogenic mediators in response to these growth factors. Altogether, these findings suggest that miR-16 and miR-424 play important roles in regulating cell-intrinsic angiogenic activity of ECs.


Assuntos
Endotélio Vascular/fisiologia , MicroRNAs/fisiologia , Neovascularização Fisiológica/fisiologia , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/fisiologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/fisiologia , Regiões 3' não Traduzidas/fisiologia , Animais , Bovinos , Movimento Celular/fisiologia , Proliferação de Células , Células Cultivadas , Endotélio Vascular/citologia , Humanos , Camundongos , Camundongos SCID , Transdução de Sinais/fisiologia , Fator A de Crescimento do Endotélio Vascular/fisiologia
20.
Comp Funct Genomics ; 2012: 475731, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22693426

RESUMO

Translation regulation plays important roles in both normal physiological conditions and diseases states. This regulation requires cis-regulatory elements located mostly in 5' and 3' UTRs and trans-regulatory factors (e.g., RNA binding proteins (RBPs)) which recognize specific RNA features and interact with the translation machinery to modulate its activity. In this paper, we discuss important aspects of 5' UTR-mediated regulation by providing an overview of the characteristics and the function of the main elements present in this region, like uORF (upstream open reading frame), secondary structures, and RBPs binding motifs and different mechanisms of translation regulation and the impact they have on gene expression and human health when deregulated.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA