Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 24
Filtrar
1.
Trends Biochem Sci ; 46(4): 270-283, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33303320

RESUMO

RNA G-quadruplexes (RG4s) are four-stranded structures known to control gene expression mechanisms, from transcription to protein synthesis, and DNA-related processes. Their potential impact on RNA biology allows these structures to shape cellular processes relevant to disease development, making their targeting for therapeutic purposes an attractive option. We review here the current knowledge on RG4s, focusing on the latest breakthroughs supporting the notion of transient structures that fluctuate dynamically in cellulo, their interplay with RNA modifications, their role in cell compartmentalization, and their deregulation impacting the host immune response. We emphasize RG4-binding proteins as determinants of their transient conformation and effectors of their biological functions.


Assuntos
Quadruplex G , Biologia , DNA , Biossíntese de Proteínas , RNA/metabolismo
2.
Nucleic Acids Res ; 51(D1): D240-D247, 2023 01 06.
Artigo em Inglês | MEDLINE | ID: mdl-36124670

RESUMO

RNA G-quadruplexes (RG4s) are non-canonical, disease-associated post-transcriptional regulators of gene expression whose functions are driven by RNA-binding proteins (RBPs). Being able to explore transcriptome-wide RG4 formation and interaction with RBPs is thus paramount to understanding how they are regulated and exploiting them as potential therapeutic targets. Towards this goal, we present QUADRatlas (https://rg4db.cibio.unitn.it), a database of experimentally-derived and computationally predicted RG4s in the human transcriptome, enriched with biological function and disease associations. As RBPs are key to their function, we mined known interactions of RG4s with such proteins, complemented with an extensive RBP binding sites dataset. Users can thus intersect RG4s with their potential regulators and effectors, enabling the formulation of novel hypotheses on RG4 regulation, function and pathogenicity. To support this capability, we provide analysis tools for predicting whether an RBP can bind RG4s, RG4 enrichment in a gene set, and de novo RG4 prediction. Genome-browser and table views allow exploring, filtering, and downloading the data quickly for individual genes and in batch. QUADRatlas is a significant step forward in our ability to understand the biology of RG4s, offering unmatched data content and enabling the integrated analysis of RG4s and their interactions with RBPs.


Assuntos
Quadruplex G , RNA , Humanos , Proteínas de Transporte/metabolismo , RNA/genética , RNA/química , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Transcriptoma , Atlas como Assunto
3.
Proc Natl Acad Sci U S A ; 116(35): 17261-17270, 2019 08 27.
Artigo em Inglês | MEDLINE | ID: mdl-31405989

RESUMO

Debilitating cancer-induced muscle wasting, a syndrome known as cachexia, is lethal. Here we report a posttranscriptional pathway involving the RNA-binding protein HuR as a key player in the onset of this syndrome. Under these conditions, HuR switches its function from a promoter of muscle fiber formation to become an inducer of muscle loss. HuR binds to the STAT3 (signal transducer and activator of transcription 3) mRNA, which encodes one of the main effectors of this condition, promoting its expression both in vitro and in vivo. While HuR does not affect the stability and the cellular movement of this transcript, HuR promotes the translation of the STAT3 mRNA by preventing miR-330 (microRNA 330)-mediated translation inhibition. To achieve this effect, HuR directly binds to a U-rich element in the STAT3 mRNA-3'untranslated region (UTR) located within the vicinity of the miR-330 seed element. Even though the binding sites of HuR and miR-330 do not overlap, the recruitment of either one of them to the STAT3-3'UTR negatively impacts the binding and the function of the other factor. Therefore, together, our data establish the competitive interplay between HuR and miR-330 as a mechanism via which muscle fibers modulate, in part, STAT3 expression to determine their fate in response to promoters of muscle wasting.


Assuntos
Proteína Semelhante a ELAV 1/metabolismo , MicroRNAs/metabolismo , Atrofia Muscular/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias Experimentais/metabolismo , Biossíntese de Proteínas , RNA Neoplásico/metabolismo , Fator de Transcrição STAT3/biossíntese , Regiões 3' não Traduzidas , Animais , Proteína Semelhante a ELAV 1/genética , Masculino , Camundongos , Camundongos Knockout , MicroRNAs/genética , Atrofia Muscular/genética , Proteínas de Neoplasias/genética , Neoplasias Experimentais/genética , Neoplasias Experimentais/patologia , RNA Neoplásico/genética , Fator de Transcrição STAT3/genética
4.
Nucleic Acids Res ; 45(4): 1584-1595, 2017 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-28013268

RESUMO

RNA G-quadruplexes (G4s) are formed by G-rich RNA sequences in protein-coding (mRNA) and non-coding (ncRNA) transcripts that fold into a four-stranded conformation. Experimental studies and bioinformatic predictions support the view that these structures are involved in different cellular functions associated to both DNA processes (telomere elongation, recombination and transcription) and RNA post-transcriptional mechanisms (including pre-mRNA processing, mRNA turnover, targeting and translation). An increasing number of different diseases have been associated with the inappropriate regulation of RNA G4s exemplifying the potential importance of these structures on human health. Here, we review the different molecular mechanisms underlying the link between RNA G4s and human diseases by proposing several overlapping models of deregulation emerging from recent research, including (i) sequestration of RNA-binding proteins, (ii) aberrant expression or localization of RNA G4-binding proteins, (iii) repeat associated non-AUG (RAN) translation, (iv) mRNA translational blockade and (v) disabling of protein-RNA G4 complexes. This review also provides a comprehensive survey of the functional RNA G4 and their mechanisms of action. Finally, we highlight future directions for research aimed at improving our understanding on RNA G4-mediated regulatory mechanisms linked to diseases.


Assuntos
Quadruplex G , RNA/química , Biologia Computacional/métodos , Predisposição Genética para Doença , Variação Genética , Humanos , Modelos Biológicos , Polimorfismo de Nucleotídeo Único , RNA/genética , RNA/metabolismo , Precursores de RNA/química , Precursores de RNA/genética , Precursores de RNA/metabolismo , RNA Mensageiro/química , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/metabolismo
5.
EMBO Rep ; 17(4): 508-18, 2016 04.
Artigo em Inglês | MEDLINE | ID: mdl-26964895

RESUMO

Ku heterodimer is a DNA binding protein with a prominent role in DNA repair. Here, we investigate whether and how Ku impacts the DNA damage response by acting as a post-transcriptional regulator of gene expression. We show that Ku represses p53 protein synthesis and p53-mediated apoptosis by binding to a bulged stem-loop structure within the p53 5' UTR However, Ku-mediated translational repression of the p53 mRNA is relieved after genotoxic stress. The underlying mechanism involves Ku acetylation which disrupts Ku-p53 mRNA interactions. These results suggest that Ku-mediated repression of p53 mRNA translation constitutes a novel mechanism linking DNA repair and mRNA translation.


Assuntos
Dano ao DNA/fisiologia , Reparo do DNA , Autoantígeno Ku/metabolismo , Biossíntese de Proteínas , RNA Mensageiro/genética , Proteína Supressora de Tumor p53/genética , Regiões 5' não Traduzidas , Acetilação , Apoptose , Dano ao DNA/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , Humanos , Autoantígeno Ku/genética , Ligação Proteica , RNA Mensageiro/metabolismo , Proteína Supressora de Tumor p53/metabolismo
6.
RNA Biol ; 12(3): 320-9, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25826664

RESUMO

The activation of translation contributes to malignant transformation and is an emerging target for cancer therapies. RNA G-quadruplex structures are general inhibitors of cap-dependent mRNA translation and were recently shown to be targeted for oncoprotein translational activation. In contrast however, the G-quadruplex within the 5'UTR of the human vascular endothelial growth factor A (VEGF) has been shown to be essential for IRES-mediated translation. Since VEGF has a pivotal role in tumor angiogenesis and is a major target of anti-tumoral therapies, we investigated the structure/function relationship of the VEGF G-quadruplex and defined whether it could have a therapeutic potential. We found that the G-quadruplex within the VEGF IRES is dispensable for cap-independent function and activation in stress conditions. However, stabilization of the VEGF G-quadruplex by increasing the G-stretches length or by replacing it with the one of NRAS results in strong inhibition of IRES-mediated translation of VEGF. We also demonstrate that G-quadruplex ligands stabilize the VEGF G-quadruplex and inhibit cap-independent translation in vitro. Importantly, the amount of human VEGF mRNA associated with polysomes decreases in the presence of a highly selective stabilizing G-quadruplex ligand, resulting in reduced VEGF protein expression. Together, our results uncover the existence of functionally silent G-quadruplex structures that are susceptible to conversion into efficient repressors of cap-independent mRNA translation. These findings have implications for the in vivo applications of G-quadruplex-targeting compounds and for anti-angiogenic therapies.


Assuntos
Regiões 5' não Traduzidas , Regulação da Expressão Gênica , Sítios Internos de Entrada Ribossomal , Biossíntese de Proteínas , Fator A de Crescimento do Endotélio Vascular/genética , Sequência de Bases , Quadruplex G , GTP Fosfo-Hidrolases/genética , GTP Fosfo-Hidrolases/metabolismo , Genes Reporter , Células HeLa , Humanos , Luciferases/genética , Luciferases/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Dados de Sequência Molecular , Polirribossomos/genética , Polirribossomos/metabolismo , Fator A de Crescimento do Endotélio Vascular/química , Fator A de Crescimento do Endotélio Vascular/metabolismo
7.
Int J Mol Sci ; 15(2): 2172-90, 2014 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-24481065

RESUMO

Glioblastomas (GBM) are very aggressive and malignant brain tumors, with frequent relapses despite an appropriate treatment combining surgery, chemotherapy and radiotherapy. In GBM, hypoxia is a characteristic feature and activation of Hypoxia Inducible Factors (HIF-1α and HIF-2α) has been associated with resistance to anti-cancer therapeutics. Int6, also named eIF3e, is the "e" subunit of the translation initiation factor eIF3, and was identified as novel regulator of HIF-2α. Eukaryotic initiation factors (eIFs) are key factors regulating total protein synthesis, which controls cell growth, size and proliferation. The functional significance of Int6 and the effect of Int6/EIF3E gene silencing on human brain GBM has not yet been described and its role on the HIFs is unknown in glioma cells. In the present study, we show that Int6/eIF3e suppression affects cell proliferation, cell cycle and apoptosis of various GBM cells. We highlight that Int6 inhibition induces a diminution of proliferation through cell cycle arrest and increased apoptosis. Surprisingly, these phenotypes are independent of global cell translation inhibition and are accompanied by decreased HIF expression when Int6 is silenced. In conclusion, we demonstrate here that Int6/eIF3e is essential for proliferation and survival of GBM cells, presumably through modulation of the HIFs.


Assuntos
Neoplasias Encefálicas/genética , Neoplasias Encefálicas/mortalidade , Fator de Iniciação 3 em Eucariotos/genética , Glioblastoma/genética , Glioblastoma/mortalidade , Apoptose/genética , Pontos de Checagem do Ciclo Celular/genética , Linhagem Celular Tumoral , Proliferação de Células , Fator de Iniciação 3 em Eucariotos/metabolismo , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Modelos Biológicos , Interferência de RNA
8.
NAR Cancer ; 6(2): zcae025, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38828391

RESUMO

Translational reprogramming in response to oncogenic signaling or microenvironmental stress factors shapes the proteome of cancer cells, enabling adaptation and phenotypic changes underlying cell plasticity, tumor progression and response to cancer therapy. Among the mechanisms regulating translation are RNA G-quadruplexes (RG4s), non-canonical four-stranded structures whose conformational modulation by small molecule ligands and RNA-binding proteins affects the expression of cancer proteins. Here, we discuss the role of RG4s in the regulation of mRNA translation by focusing on paradigmatic examples showing their contribution to adaptive mechanisms of mRNA translation in cancer.

9.
Methods Mol Biol ; 2404: 69-81, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34694604

RESUMO

mRNA translation is a key step in gene expression that allows the cell to qualitatively and quantitatively modulate the cell's proteome according to intra- or extracellular signals. Polysome profiling is the most comprehensive technique to study both the translation state of mRNAs and the protein machinery associated with the mRNAs being translated. Here we describe the procedure commonly used in our laboratory to gain insights into the molecular mechanisms underlying translation regulation under pathophysiological conditions.


Assuntos
Biossíntese de Proteínas , Perfilação da Expressão Gênica , Polirribossomos/genética , Polirribossomos/metabolismo , Proteínas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
10.
Cancers (Basel) ; 14(5)2022 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-35267591

RESUMO

Deregulation of mRNA translation is a widespread characteristic of glioblastoma (GBM), aggressive malignant brain tumors that are resistant to conventional therapies. RNA-binding proteins (RBPs) play a critical role in translational regulation, yet the mechanisms and impact of these regulations on cancer development, progression and response to therapy remain to be fully understood. Here, we showed that hnRNP H/F RBPs are potent regulators of translation through several mechanisms that converge to modulate the expression and/or the activity of translation initiation factors. Among these, hnRNP H/F regulate the phosphorylation of eIF4E and its translational targets by controlling RNA splicing of the A-Raf kinase mRNA, which in turn modulates the MEK-ERK/MAPK signaling pathway. The underlying mechanism involves RNA G-quadruplex (RG4s), RNA structures whose modulation phenocopies hnRNP H/F translation regulation in GBM cells. Our results highlighted that hnRNP H/F are essential for key functional pathways regulating proliferation and survival of GBM, highlighting its targeting as a promising strategy for improving therapeutic outcomes.

11.
J Virol ; 84(19): 10139-47, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20631141

RESUMO

Mutations in the internal ribosome entry site (IRES) of hepatitis A virus (HAV) have been associated with enhanced in vitro replication and viral attenuation in animal models. To address the possible role of IRES variability in clinical presentation, IRES sequences were obtained from HAV isolates associated with benign (n = 8) or severe (n = 4) hepatitis. IRES activity was assessed using a bicistronic dual-luciferase expression system in adenocarcinoma (HeLa) and hepatoma (HuH7) cell lines. Activity was higher in HuH7 than in HeLa cells, except for an infrequently isolated genotype IIA strain. Though globally low, significant variation in IRES-dependent translation efficiency was observed between field isolates, reflecting the low but significant genetic variability of this region (94.2% +/- 0.5% nucleotide identity). No mutation was exclusive of benign or severe hepatitis, and variations in IRES activity were not associated with a clinical phenotype, indirectly supporting the preponderance of host factors in determining the clinical presentation.


Assuntos
Regiões 5' não Traduzidas/genética , Vírus da Hepatite A/genética , Vírus da Hepatite A/patogenicidade , Hepatite A/virologia , RNA Viral/genética , Doença Aguda , Adolescente , Adulto , Sequência de Bases , Linhagem Celular , Criança , Primers do DNA/genética , DNA Viral/genética , França , Variação Genética , Genótipo , Células HeLa , Vírus da Hepatite A/isolamento & purificação , Vírus da Hepatite A/fisiologia , Humanos , Pessoa de Meia-Idade , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Mutação , Conformação de Ácido Nucleico , Filogenia , Biossíntese de Proteínas , RNA Viral/química , Virulência/genética , Adulto Jovem
12.
Gut ; 59(7): 934-42, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20442199

RESUMO

BACKGROUND: Plasma hepatitis C virus (HCV) originates from hepatocytes. However, in certain subjects, B cells may harbour both plasma strains and occult HCV strains tha t are not detected in the plasma. The internal ribosome entry site (IRES) of these latter strains is mutated, suggesting that the efficiency of viral translation could drive the cellular tropism of HCV. AIMS: To determine if the translational efficiency of IRES variants in cultured hepatocytes or B cells is correlated with their cellular tropism in vivo. METHODS: The efficiency of IRES of 10 B cell-specific variants and nine plasma variants, isolated from six patients with compartmentalised variants in B cells, was estimated by bicistronic dual luciferase expression in hepatocyte cell types (Huh7), in primary cultured human hepatocytes (PCHs) and in two B cell lines (Raji and Daudi). RESULTS: For each of the six subjects, the plasma IRESes were significantly and repeatedly more efficient than B cell IRESes in Huh7 (1.7+/-0.3 vs 0.7+/-0.2; p<0.01) and PCH cells. In B cell lines, B cell and plasma IRES had similar low efficiencies (0.8+/-0.1 vs 0.9+/-0.1; NS). For three subjects, two IRES variants from the same compartment could be analysed, and had the same efficiency in each cell type. Silencing the lupus antigen, a known IRES trans-acting factor, inhibited plasma IRES variants to a greater extent than B cell-specific IRESes. CONCLUSIONS: B cells can harbour occult variants that have a poor translational efficiency in hepatocytes, strongly suggesting their extra-hepatic origin and raising the hypothesis that competition between HCV variants with different IRESes is driven at a translational level in hepatic, as well as in extra-hepatic, sites.


Assuntos
Linfócitos B/virologia , Hepacivirus/genética , Hepatite C Crônica/virologia , Hepatócitos/virologia , Adulto , Sequência de Bases , Células Cultivadas , Feminino , Hepacivirus/isolamento & purificação , Hepacivirus/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Filogenia , Biossíntese de Proteínas , Alinhamento de Sequência , Células Tumorais Cultivadas , Carga Viral , Tropismo Viral/genética , Replicação Viral/genética
13.
Mol Biol Cell ; 18(12): 5048-59, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17898077

RESUMO

Heterogeneous nuclear ribonucleoprotein (hnRNP) A1 is a nucleocytoplasmic shuttling protein that regulates gene expression through its action on mRNA metabolism and translation. The cytoplasmic redistribution of hnRNP A1 is a regulated process during viral infection and cellular stress. Here, we show that hnRNP A1 is an internal ribosome entry site (IRES) trans-acting factor that binds specifically to the 5' untranslated region of both the human rhinovirus-2 and the human apoptotic peptidase activating factor 1 (apaf-1) mRNAs, thereby regulating their translation. Furthermore, the cytoplasmic redistribution of hnRNP A1 after rhinovirus infection leads to enhanced rhinovirus IRES-mediated translation, whereas the cytoplasmic relocalization of hnRNP A1 after UVC irradiation limits the UVC-triggered translational activation of the apaf-1 IRES. Therefore, this study provides a direct demonstration that IRESs behave as translational enhancer elements regulated by specific trans-acting mRNA binding proteins in given physiological conditions. Our data highlight a new way to regulate protein synthesis in eukaryotes through the subcellular relocalization of a nuclear mRNA-binding protein.


Assuntos
Citoplasma/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas Grupo A-B/metabolismo , Biossíntese de Proteínas/genética , Fator Apoptótico 1 Ativador de Proteases/genética , Fator Apoptótico 1 Ativador de Proteases/metabolismo , Regulação da Expressão Gênica , Células HeLa , Ribonucleoproteína Nuclear Heterogênea A1 , Humanos , Ligação Proteica , Biossíntese de Proteínas/efeitos da radiação , Transporte Proteico , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , Rhinovirus/genética , Rhinovirus/metabolismo , Ribossomos/metabolismo
14.
Nat Commun ; 11(1): 2661, 2020 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-32461552

RESUMO

RNA G-quadruplexes (RG4s) are four-stranded structures known to control mRNA translation of cancer relevant genes. RG4 formation is pervasive in vitro but not in cellulo, indicating the existence of poorly characterized molecular machinery that remodels RG4s and maintains them unfolded. Here, we performed a quantitative proteomic screen to identify cytosolic proteins that interact with a canonical RG4 in its folded and unfolded conformation. Our results identified hnRNP H/F as important components of the cytoplasmic machinery modulating the structural integrity of RG4s, revealed their function in RG4-mediated translation and uncovered the underlying molecular mechanism impacting the cellular stress response linked to the outcome of glioblastoma.


Assuntos
Quadruplex G , Glioblastoma/fisiopatologia , Ribonucleoproteínas Nucleares Heterogêneas Grupo F-H/metabolismo , Neoplasias Encefálicas/fisiopatologia , Linhagem Celular Tumoral , RNA Helicases DEAD-box/metabolismo , Regulação da Expressão Gênica/fisiologia , Instabilidade Genômica/fisiologia , Humanos , RNA Mensageiro/metabolismo
15.
NAR Cancer ; 2(3): zcaa020, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34316689

RESUMO

Intrinsic resistance to current therapies, leading to dismal clinical outcomes, is a hallmark of glioblastoma multiforme (GBM), the most common and aggressive brain tumor. Understanding the underlying mechanisms of such malignancy is, therefore, an urgent medical need. Deregulation of the protein translation machinery has been shown to contribute to cancer initiation and progression, in part by driving selective translational control of specific mRNA transcripts involved in distinct cancer cell behaviors. Here, we focus on eIF3, a multimeric complex with a known role in the initiation of translation and that is frequently deregulated in cancer. Our results show that the deregulated expression of eIF3e, the e subunit of eIF3, in specific GBM regions could impinge on selective protein synthesis impacting the GBM outcome. In particular, eIF3e restricts the expression of proteins involved in the response to cellular stress and increases the expression of key functional regulators of cell stemness. Such a translation program can therefore serve as a double-edged sword promoting GBM tumor growth and resistance to radiation.

16.
Cell Rep ; 26(1): 94-107.e7, 2019 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-30605689

RESUMO

Despite the clinical success of blocking inhibitory immune checkpoint receptors such as programmed cell death-1 (PD-1) in cancer, the mechanisms controlling the expression of these receptors have not been fully elucidated. Here, we identify a post-transcriptional mechanism regulating PD-1 expression in T cells. Upon activation, the PDCD1 mRNA and ribonucleoprotein complexes coalesce into stress granules that require microtubules and the kinesin 1 molecular motor to proceed to translation. Hence, PD-1 expression is highly sensitive to microtubule or stress granule inhibitors targeting this pathway. Evidence from healthy donors and cancer patients reveals a common regulation for the translation of CTLA4, LAG3, TIM3, TIGIT, and BTLA but not of the stimulatory co-receptors OX40, GITR, and 4-1BB mRNAs. In patients, disproportionality analysis of immune-related adverse events for currently used microtubule drugs unveils a significantly higher risk of autoimmunity. Our findings reveal a fundamental mechanism of immunoregulation with great importance in cancer immunotherapy.


Assuntos
Imunoterapia/métodos , Microtúbulos/metabolismo , Linfócitos T/imunologia , Humanos
17.
Oncotarget ; 7(13): 16793-805, 2016 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-26930004

RESUMO

The expression and role of RNA binding proteins (RBPs) controlling mRNA translation during tumor progression remains largely uncharacterized. Analysis by immunohistochemistry of the expression of hnRNP A1, hnRNPH, RBM9/FOX2, SRSF1/ASF/SF2, SRSF2/SC35, SRSF3/SRp20, SRSF7/9G8 in breast tumors shows that the expression of hnRNP A1, but not the other tested RBPs, is associated with metastatic relapse. Strikingly, hnRNP A1, a nuclear splicing regulator, is also present in the cytoplasm of tumor cells of a subset of patients displaying exceedingly worse prognosis. Expression of a cytoplasmic mutant of hnRNP A1 leads to increased translation of the mRNA encoding the tyrosine kinase receptor RON/MTS1R, known for its function in tumor dissemination, and increases cell migration in vitro. hnRNP A1 directly binds to the 5' untranslated region of the RON mRNA and activates its translation through G-quadruplex RNA secondary structures. The correlation between hnRNP A1 and RON tumoral expression suggests that these findings hold clinical relevance.


Assuntos
Neoplasias da Mama/patologia , Regulação Neoplásica da Expressão Gênica/fisiologia , Ribonucleoproteína Nuclear Heterogênea A1/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/mortalidade , Progressão da Doença , Feminino , Ribonucleoproteína Nuclear Heterogênea A1/genética , Humanos , Estimativa de Kaplan-Meier , Biossíntese de Proteínas/fisiologia , RNA Mensageiro , Receptores Proteína Tirosina Quinases/genética
19.
Nat Commun ; 5: 4190, 2014 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-24969639

RESUMO

HuR promotes myogenesis by stabilizing the MyoD, myogenin and p21 mRNAs during the fusion of muscle cells to form myotubes. Here we show that HuR, via a novel mRNA destabilizing activity, promotes the early steps of myogenesis by reducing the expression of the cell cycle promoter nucleophosmin (NPM). Depletion of HuR stabilizes the NPM mRNA, increases NPM protein levels and inhibits myogenesis, while its overexpression elicits the opposite effects. NPM mRNA destabilization involves the association of HuR with the decay factor KSRP as well as the ribonuclease PARN and the exosome. The C terminus of HuR mediates the formation of the HuR-KSRP complex and is sufficient for maintaining a low level of the NPM mRNA as well as promoting the commitment of muscle cells to myogenesis. We therefore propose a model whereby the downregulation of the NPM mRNA, mediated by HuR, KSRP and its associated ribonucleases, is required for proper myogenesis.


Assuntos
Proteínas ELAV/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/genética , Desenvolvimento Muscular/genética , Fibras Musculares Esqueléticas/metabolismo , Proteínas Nucleares/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/metabolismo , Transativadores/metabolismo , Animais , Humanos , Camundongos , Proteína MyoD/genética , Miogenina/genética , Proteínas Nucleares/metabolismo , Nucleofosmina , Regiões Promotoras Genéticas , Estabilidade de RNA
20.
Nat Commun ; 4: 2388, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24005720

RESUMO

Upon muscle injury, the high mobility group box 1 (HMGB1) protein is upregulated and secreted to initiate reparative responses. Here we show that HMGB1 controls myogenesis both in vitro and in vivo during development and after adult muscle injury. HMGB1 expression in muscle cells is regulated at the translational level: the miRNA miR-1192 inhibits HMGB1 translation and the RNA-binding protein HuR promotes it. HuR binds to a cis-element, HuR binding sites (HuRBS), located in the 3'UTR of the HMGB1 transcript, and at the same time miR-1192 is recruited to an adjacent seed element. The binding of HuR to the HuRBS prevents the recruitment of Argonaute 2 (Ago2), overriding miR-1192-mediated translation inhibition. Depleting HuR reduces myoblast fusion and silencing miR-1192 re-establishes the fusion potential of HuR-depleted cells. We propose that HuR promotes the commitment of myoblasts to myogenesis by enhancing the translation of HMGB1 and suppressing the translation inhibition mediated by miR-1192.


Assuntos
Proteínas ELAV/metabolismo , Proteína HMGB1/genética , MicroRNAs/metabolismo , Desenvolvimento Muscular/genética , Biossíntese de Proteínas , Regiões 3' não Traduzidas/genética , Animais , Sequência de Bases , Sítios de Ligação/genética , Extratos Celulares , Linhagem Celular , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Inativação Gênica , Proteína HMGB1/metabolismo , Camundongos , MicroRNAs/genética , Dados de Sequência Molecular , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Mioblastos/metabolismo , Ligação Proteica/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Regeneração/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA