Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Nat Commun ; 12(1): 4245, 2021 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-34253722

RESUMO

Tuberous Sclerosis Complex (TSC) is caused by TSC1 or TSC2 mutations, resulting in hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1). Transcription factor EB (TFEB), a master regulator of lysosome biogenesis, is negatively regulated by mTORC1 through a RAG GTPase-dependent phosphorylation. Here we show that lysosomal biogenesis is increased in TSC-associated renal tumors, pulmonary lymphangioleiomyomatosis, kidneys from Tsc2+/- mice, and TSC1/2-deficient cells via a TFEB-dependent mechanism. Interestingly, in TSC1/2-deficient cells, TFEB is hypo-phosphorylated at mTORC1-dependent sites, indicating that mTORC1 is unable to phosphorylate TFEB in the absence of the TSC1/2 complex. Importantly, overexpression of folliculin (FLCN), a GTPase activating protein for RAGC, increases TFEB phosphorylation at the mTORC1 sites in TSC2-deficient cells. Overexpression of constitutively active RAGC is sufficient to relocalize TFEB to the cytoplasm. These findings establish the TSC proteins as critical regulators of lysosomal biogenesis via TFEB and RAGC and identify TFEB as a driver of the proliferation of TSC2-deficient cells.


Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Lisossomos/metabolismo , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Biogênese de Organelas , Proteína 2 do Complexo Esclerose Tuberosa/metabolismo , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Carcinoma de Células Renais/patologia , Núcleo Celular/metabolismo , Proliferação de Células , Feminino , Regulação da Expressão Gênica , Células HEK293 , Células HeLa , Humanos , Neoplasias Renais/patologia , Lisossomos/ultraestrutura , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Fosforilação , Fosfosserina/metabolismo , Transporte Proteico , Proteínas Proto-Oncogênicas/metabolismo , Transcrição Genética , Proteína 2 do Complexo Esclerose Tuberosa/deficiência , Proteínas Supressoras de Tumor/metabolismo
2.
Nat Commun ; 12(1): 808, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-33547292

RESUMO

Sarcomatoid and rhabdoid (S/R) renal cell carcinoma (RCC) are highly aggressive tumors with limited molecular and clinical characterization. Emerging evidence suggests immune checkpoint inhibitors (ICI) are particularly effective for these tumors, although the biological basis for this property is largely unknown. Here, we evaluate multiple clinical trial and real-world cohorts of S/R RCC to characterize their molecular features, clinical outcomes, and immunologic characteristics. We find that S/R RCC tumors harbor distinctive molecular features that may account for their aggressive behavior, including BAP1 mutations, CDKN2A deletions, and increased expression of MYC transcriptional programs. We show that these tumors are highly responsive to ICI and that they exhibit an immune-inflamed phenotype characterized by immune activation, increased cytotoxic immune infiltration, upregulation of antigen presentation machinery genes, and PD-L1 expression. Our findings build on prior work and shed light on the molecular drivers of aggressivity and responsiveness to ICI of S/R RCC.


Assuntos
Antineoplásicos Imunológicos/uso terapêutico , Carcinoma de Células Renais/imunologia , Regulação Neoplásica da Expressão Gênica , Inibidores de Checkpoint Imunológico/uso terapêutico , Proteínas de Checkpoint Imunológico/imunologia , Neoplasias Renais/imunologia , Tumor Rabdoide/imunologia , Antígeno B7-H1/antagonistas & inibidores , Antígeno B7-H1/genética , Antígeno B7-H1/imunologia , Antígeno CTLA-4/antagonistas & inibidores , Antígeno CTLA-4/genética , Antígeno CTLA-4/imunologia , Carcinoma de Células Renais/tratamento farmacológico , Carcinoma de Células Renais/genética , Carcinoma de Células Renais/mortalidade , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidor p16 de Quinase Dependente de Ciclina/imunologia , Perfilação da Expressão Gênica , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Proteínas de Checkpoint Imunológico/genética , Neoplasias Renais/tratamento farmacológico , Neoplasias Renais/genética , Neoplasias Renais/mortalidade , Mutação , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Receptor de Morte Celular Programada 1/genética , Receptor de Morte Celular Programada 1/imunologia , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/imunologia , Estudos Retrospectivos , Tumor Rabdoide/tratamento farmacológico , Tumor Rabdoide/genética , Tumor Rabdoide/mortalidade , Transdução de Sinais , Análise de Sobrevida , Transcrição Genética , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/imunologia , Ubiquitina Tiolesterase/genética , Ubiquitina Tiolesterase/imunologia
3.
Nat Genet ; 52(8): 790-799, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32690948

RESUMO

Epigenetic processes govern prostate cancer (PCa) biology, as evidenced by the dependency of PCa cells on the androgen receptor (AR), a prostate master transcription factor. We generated 268 epigenomic datasets spanning two state transitions-from normal prostate epithelium to localized PCa to metastases-in specimens derived from human tissue. We discovered that reprogrammed AR sites in metastatic PCa are not created de novo; rather, they are prepopulated by the transcription factors FOXA1 and HOXB13 in normal prostate epithelium. Reprogrammed regulatory elements commissioned in metastatic disease hijack latent developmental programs, accessing sites that are implicated in prostate organogenesis. Analysis of reactivated regulatory elements enabled the identification and functional validation of previously unknown metastasis-specific enhancers at HOXB13, FOXA1 and NKX3-1. Finally, we observed that prostate lineage-specific regulatory elements were strongly associated with PCa risk heritability and somatic mutation density. Examining prostate biology through an epigenomic lens is fundamental for understanding the mechanisms underlying tumor progression.


Assuntos
Neoplasias da Próstata/genética , Linhagem Celular , Linhagem Celular Tumoral , Progressão da Doença , Epigenômica/métodos , Regulação Neoplásica da Expressão Gênica/genética , Células HEK293 , Fator 3-alfa Nuclear de Hepatócito/genética , Humanos , Masculino , Próstata/patologia , Neoplasias da Próstata/patologia , Receptores Androgênicos/genética , Sequências Reguladoras de Ácido Nucleico/genética
4.
Cell ; 174(2): 433-447.e19, 2018 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-29909985

RESUMO

Nearly all prostate cancer deaths are from metastatic castration-resistant prostate cancer (mCRPC), but there have been few whole-genome sequencing (WGS) studies of this disease state. We performed linked-read WGS on 23 mCRPC biopsy specimens and analyzed cell-free DNA sequencing data from 86 patients with mCRPC. In addition to frequent rearrangements affecting known prostate cancer genes, we observed complex rearrangements of the AR locus in most cases. Unexpectedly, these rearrangements include highly recurrent tandem duplications involving an upstream enhancer of AR in 70%-87% of cases compared with <2% of primary prostate cancers. A subset of cases displayed AR or MYC enhancer duplication in the context of a genome-wide tandem duplicator phenotype associated with CDK12 inactivation. Our findings highlight the complex genomic structure of mCRPC, nominate alterations that may inform prostate cancer treatment, and suggest that additional recurrent events in the non-coding mCRPC genome remain to be discovered.


Assuntos
Neoplasias de Próstata Resistentes à Castração/patologia , Receptores Androgênicos/genética , Sequenciamento Completo do Genoma , Idoso , Anilidas/uso terapêutico , Quinases Ciclina-Dependentes/genética , Quinases Ciclina-Dependentes/metabolismo , Elementos Facilitadores Genéticos/genética , Duplicação Gênica , Rearranjo Gênico , Genes myc , Loci Gênicos , Haplótipos , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , PTEN Fosfo-Hidrolase/genética , Fenótipo , Antígeno Prostático Específico/sangue , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Neoplasias de Próstata Resistentes à Castração/genética , Inibidores de Proteínas Quinases/uso terapêutico , Piridinas/uso terapêutico
5.
Nat Genet ; 50(7): 937-943, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29955178

RESUMO

Functional redundancy shared by paralog genes may afford protection against genetic perturbations, but it can also result in genetic vulnerabilities due to mutual interdependency1-5. Here, we surveyed genome-scale short hairpin RNA and CRISPR screening data on hundreds of cancer cell lines and identified MAGOH and MAGOHB, core members of the splicing-dependent exon junction complex, as top-ranked paralog dependencies6-8. MAGOHB is the top gene dependency in cells with hemizygous MAGOH deletion, a pervasive genetic event that frequently occurs due to chromosome 1p loss. Inhibition of MAGOHB in a MAGOH-deleted context compromises viability by globally perturbing alternative splicing and RNA surveillance. Dependency on IPO13, an importin-ß receptor that mediates nuclear import of the MAGOH/B-Y14 heterodimer9, is highly correlated with dependency on both MAGOH and MAGOHB. Both MAGOHB and IPO13 represent dependencies in murine xenografts with hemizygous MAGOH deletion. Our results identify MAGOH and MAGOHB as reciprocal paralog dependencies across cancer types and suggest a rationale for targeting the MAGOHB-IPO13 axis in cancers with chromosome 1p deletion.


Assuntos
Cromossomos Humanos Par 1 , Neoplasias/genética , Animais , Linhagem Celular Tumoral , Núcleo Celular/genética , Éxons/genética , Feminino , Deleção de Genes , Células HEK293 , Humanos , Carioferinas/genética , Camundongos , Camundongos Nus , Proteínas Nucleares/genética , Splicing de RNA/genética , RNA Interferente Pequeno/genética
6.
Nature ; 547(7664): 453-457, 2017 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-28678785

RESUMO

Plasticity of the cell state has been proposed to drive resistance to multiple classes of cancer therapies, thereby limiting their effectiveness. A high-mesenchymal cell state observed in human tumours and cancer cell lines has been associated with resistance to multiple treatment modalities across diverse cancer lineages, but the mechanistic underpinning for this state has remained incompletely understood. Here we molecularly characterize this therapy-resistant high-mesenchymal cell state in human cancer cell lines and organoids and show that it depends on a druggable lipid-peroxidase pathway that protects against ferroptosis, a non-apoptotic form of cell death induced by the build-up of toxic lipid peroxides. We show that this cell state is characterized by activity of enzymes that promote the synthesis of polyunsaturated lipids. These lipids are the substrates for lipid peroxidation by lipoxygenase enzymes. This lipid metabolism creates a dependency on pathways converging on the phospholipid glutathione peroxidase (GPX4), a selenocysteine-containing enzyme that dissipates lipid peroxides and thereby prevents the iron-mediated reactions of peroxides that induce ferroptotic cell death. Dependency on GPX4 was found to exist across diverse therapy-resistant states characterized by high expression of ZEB1, including epithelial-mesenchymal transition in epithelial-derived carcinomas, TGFß-mediated therapy-resistance in melanoma, treatment-induced neuroendocrine transdifferentiation in prostate cancer, and sarcomas, which are fixed in a mesenchymal state owing to their cells of origin. We identify vulnerability to ferroptic cell death induced by inhibition of a lipid peroxidase pathway as a feature of therapy-resistant cancer cells across diverse mesenchymal cell-state contexts.


Assuntos
Glutationa Peroxidase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Neoplasias/enzimologia , Caderinas/metabolismo , Morte Celular , Linhagem Celular Tumoral , Linhagem da Célula , Transdiferenciação Celular , Resistencia a Medicamentos Antineoplásicos/genética , Transição Epitelial-Mesenquimal , Humanos , Ferro/metabolismo , Peróxidos Lipídicos/metabolismo , Masculino , Melanoma/tratamento farmacológico , Melanoma/enzimologia , Melanoma/metabolismo , Melanoma/patologia , Mesoderma/efeitos dos fármacos , Mesoderma/enzimologia , Mesoderma/metabolismo , Mesoderma/patologia , Neoplasias/genética , Neoplasias/patologia , Fosfolipídeo Hidroperóxido Glutationa Peroxidase , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/enzimologia , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Proteômica , Proteínas Proto-Oncogênicas B-raf/genética , Reprodutibilidade dos Testes , Homeobox 1 de Ligação a E-box em Dedo de Zinco/genética
7.
Genes Dev ; 29(10): 1074-86, 2015 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-25956904

RESUMO

Colorectal cancer (CRC) remains a major contributor to cancer-related mortality. LIN28A and LIN28B are highly related RNA-binding protein paralogs that regulate biogenesis of let-7 microRNAs and influence development, metabolism, tissue regeneration, and oncogenesis. Here we demonstrate that overexpression of either LIN28 paralog cooperates with the Wnt pathway to promote invasive intestinal adenocarcinoma in murine models. When LIN28 alone is induced genetically, half of the resulting tumors harbor Ctnnb1 (ß-catenin) mutation. When overexpressed in Apc(Min/+) mice, LIN28 accelerates tumor formation and enhances proliferation and invasiveness. In conditional genetic models, enforced expression of a LIN28-resistant form of the let-7 microRNA reduces LIN28-induced tumor burden, while silencing of LIN28 expression reduces tumor volume and increases tumor differentiation, indicating that LIN28 contributes to tumor maintenance. We detected aberrant expression of LIN28A and/or LIN28B in 38% of a large series of human CRC samples (n = 595), where LIN28 expression levels were associated with invasive tumor growth. Our late-stage CRC murine models and analysis of primary human tumors demonstrate prominent roles for both LIN28 paralogs in promoting CRC growth and progression and implicate the LIN28/let-7 pathway as a therapeutic target.


Assuntos
Adenocarcinoma/fisiopatologia , Neoplasias Colorretais/fisiopatologia , Proteínas de Ligação a RNA/metabolismo , Transdução de Sinais , Proteínas Wnt/metabolismo , Animais , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Invasividade Neoplásica/genética , Invasividade Neoplásica/fisiopatologia , Proteínas de Ligação a RNA/genética
8.
Med Oncol ; 28(3): 810-2, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20407853

RESUMO

Lymphomatous involvement of the gallbladder is extremely rare. We report on a 69-year-old woman with a history of an indolent non-Hodgkin's lymphoma who was found to have a new gallbladder lesion on surveillance CT scan. The mass was resected and proved to be a follicular lymphoma with the same immunohistochemical characteristics as her original tumor 12 years prior.


Assuntos
Neoplasias da Vesícula Biliar/patologia , Linfoma Folicular/patologia , Recidiva Local de Neoplasia/patologia , Idoso , Feminino , Neoplasias da Vesícula Biliar/diagnóstico por imagem , Humanos , Linfoma Folicular/diagnóstico por imagem , Recidiva Local de Neoplasia/diagnóstico por imagem , Tomografia Computadorizada por Raios X
9.
Nat Genet ; 42(7): 626-30, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20512147

RESUMO

Recently, genome-wide association studies have implicated the human LIN28B locus in regulating height and the timing of menarche. LIN28B and its homolog LIN28A are functionally redundant RNA-binding proteins that block biogenesis of let-7 microRNAs. lin-28 and let-7 were discovered in Caenorhabditis elegans as heterochronic regulators of larval and vulval development but have recently been implicated in cancer, stem cell aging and pluripotency. The let-7 targets Myc, Kras, Igf2bp1 and Hmga2 are known regulators of mammalian body size and metabolism. To explore the function of the Lin28-Let-7 pathway in vivo, we engineered transgenic mice to express Lin28a and observed in them increased body size, crown-rump length and delayed onset of puberty. Investigation of metabolic and endocrine mechanisms of overgrowth in these transgenic mice revealed increased glucose metabolism and insulin sensitivity. Here we report a mouse that models the human phenotypes associated with genetic variation in the Lin28-Let-7 pathway.


Assuntos
Tamanho Corporal/fisiologia , Estudos de Associação Genética , Proteínas de Ligação a RNA/metabolismo , Maturidade Sexual/fisiologia , Animais , Glicemia/metabolismo , Tamanho Corporal/genética , Feminino , Perfilação da Expressão Gênica , Glucose/metabolismo , Humanos , Insulina/sangue , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , MicroRNAs/genética , MicroRNAs/metabolismo , Modelos Animais , Análise de Sequência com Séries de Oligonucleotídeos , Fenótipo , Proteínas de Ligação a RNA/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Maturidade Sexual/genética , Fatores de Tempo
10.
Cell ; 140(4): 445-9, 2010 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-20178735

RESUMO

Lin28, a highly conserved RNA-binding protein, has emerged as a modulator of the processing of the let-7 microRNA. This role for Lin28 has important implications for our mechanistic understanding of pluripotency, the timing of development, and oncogenesis.


Assuntos
MicroRNAs/genética , Processamento de Proteína Pós-Traducional , Proteínas de Ligação a RNA/genética , Animais , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Neoplasias/metabolismo , Células-Tronco/metabolismo
11.
J Biol Chem ; 284(43): 29269-82, 2009 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-19690161

RESUMO

Kaposi sarcoma-associated herpesvirus-encoded interleukin-6 (vIL-6) and its human cellular homologue (huIL-6) share similar biological functions. Our previous work showed that N-linked glycosylation was required for optimal function of vIL6 but not huIL-6 (1). Here we describe heterogeneity in the composition of the glycans of the two N-linked sites of vIL-6. The Asn-89 site of vIL-6, found to be required for optimal cytokine function, is composed of complex glycans. The Asn-78 site is composed of high mannose glycans, which are dispensable for cytokine function. N-Linked glycosylation at the Asn-89 site was required for intracellular production of functional vIL-6, but endoglycosidase-mediated removal of N-linked glycans from secreted vIL-6 did not impair protein function. With the use of a conformation-specific antibody and tryptic digestion assays, we showed that glycosylation at the Asn-89 site of vIL-6 affected protein conformation. Human IL-6, but not vIL-6, requires IL-6Ralpha for binding to gp130. We tested the hypothesis that the Asn-89 complex glycan of vIL-6 alone was sufficient to confer binding to gp130 independently of IL-6Ralpha. Two mutants of huIL-6, made to contain additional complex N-linked glycans in the region that interacts with IL-6Ralpha, did not confer binding to gp130 independently of IL-6Ralpha. Our findings support the conclusion that complex glycans on Asn-89 of vIL-6 specifically promote a protein conformation that allows the viral cytokine to bind gp130 independently of IL-6Ralpha.


Assuntos
Receptor gp130 de Citocina/metabolismo , Herpesvirus Humano 8/metabolismo , Interleucina-6/metabolismo , Polissacarídeos/metabolismo , Dobramento de Proteína , Receptores de Interleucina-6/metabolismo , Proteínas Virais/metabolismo , Anticorpos Antivirais/farmacologia , Linhagem Celular Tumoral , Receptor gp130 de Citocina/genética , Glucosidases/genética , Glucosidases/metabolismo , Glicosilação , Herpesvirus Humano 8/genética , Humanos , Interleucina-6/genética , Mutação , Polissacarídeos/genética , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/genética , Estrutura Terciária de Proteína/efeitos dos fármacos , Receptores de Interleucina-6/genética , Proteínas Virais/genética
12.
PLoS One ; 4(7): e6143, 2009 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-19582159

RESUMO

BACKGROUND: Segregation of the trophectoderm from the inner cell mass of the embryo represents the first cell-fate decision of mammalian development. Transcription factors essential for specifying trophectoderm have been identified, but the role of microRNAs (miRNAs) in modulating this fate-choice has been largely unexplored. We have compared miRNA expression in embryonic stem cell (ESC)-derived trophectoderm and in staged murine embryos to identify a set of candidate miRNAs likely to be involved in trophectoderm specification. RESULTS: We profiled embryonic stem cells (ESCs) as they were induced to differentiate into trophectodermal cells by ectopic expression of HRas/Q61L. We also profiled murine embryos at progressive stages of preimplantation development (zygote, 2-cell, 4-cell, 8-cell, morula, and blastocyst), which includes the time window in which the trophectoderm is specified in vivo Q61L/H. CONCLUSIONS: We describe miRNA expression changes that occur during trophectoderm specification and validate that our in vitro system faithfully recapitulates trophectoderm specification in vivo. By comparing our in vitro and in vivo datasets, we have identified a minimal set of candidate miRNAs likely to play a role in trophectoderm specification. These miRNAs are predicted to regulate a host of development-associated target genes, and many of these miRNAs have previously reported roles in development and differentiation. Additionally, we highlight a number of miRNAs whose tight developmental regulation may reflect a functional role in other stages of embryogenesis. Our embryo profiling data may be useful to investigators studying trophectoderm specification and other stages of preimplantation development.


Assuntos
Linhagem da Célula , Ectoderma/citologia , MicroRNAs/genética , Animais , Blastocisto , Diferenciação Celular/genética , Camundongos , Células-Tronco Pluripotentes/citologia
13.
Nature ; 460(7257): 909-13, 2009 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-19578360

RESUMO

The rarity and inaccessibility of the earliest primordial germ cells (PGCs) in the mouse embryo thwart efforts to investigate molecular mechanisms of germ-cell specification. stella (also called Dppa3) marks the rare founder population of the germ lineage. Here we differentiate mouse embryonic stem cells carrying a stella transgenic reporter into putative PGCs in vitro. The Stella(+) cells possess a transcriptional profile similar to embryo-derived PGCs, and like their counterparts in vivo, lose imprints in a time-dependent manner. Using inhibitory RNAs to screen candidate genes for effects on the development of Stella(+) cells in vitro, we discovered that Lin28, a negative regulator of let-7 microRNA processing, is essential for proper PGC development. Furthermore, we show that Blimp1 (also called Prdm1), a let-7 target and a master regulator of PGC specification, can rescue the effect of Lin28 deficiency during PGC development, thereby establishing a mechanism of action for Lin28 during PGC specification. Overexpression of Lin28 promotes formation of Stella(+) cells in vitro and PGCs in chimaeric embryos, and is associated with human germ-cell tumours. The differentiation of putative PGCs from embryonic stem cells in vitro recapitulates the early stages of gamete development in vivo, and provides an accessible system for discovering novel genes involved in germ-cell development and malignancy.


Assuntos
Diferenciação Celular , Células Germinativas/citologia , Células Germinativas/metabolismo , Neoplasias Embrionárias de Células Germinativas/metabolismo , Neoplasias Embrionárias de Células Germinativas/patologia , Proteínas de Ligação a RNA/metabolismo , Animais , Linhagem Celular , Proteínas Cromossômicas não Histona , Células-Tronco Embrionárias/citologia , Células-Tronco Embrionárias/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Células Germinativas/patologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Neoplasias Embrionárias de Células Germinativas/genética , Fator 1 de Ligação ao Domínio I Regulador Positivo , Proteínas de Ligação a RNA/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Fatores de Transcrição/metabolismo , Transgenes
14.
Nat Genet ; 41(7): 843-8, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19483683

RESUMO

Multiple members of the let-7 family of miRNAs are often repressed in human cancers, thereby promoting oncogenesis by derepressing targets such as HMGA2, K-Ras and c-Myc. However, the mechanism by which let-7 miRNAs are coordinately repressed is unclear. The RNA-binding proteins LIN28 and LIN28B block let-7 precursors from being processed to mature miRNAs, suggesting that their overexpression might promote malignancy through repression of let-7. Here we show that LIN28 and LIN28B are overexpressed in primary human tumors and human cancer cell lines (overall frequency approximately 15%), and that overexpression is linked to repression of let-7 family miRNAs and derepression of let-7 targets. LIN28 and LIN28b facilitate cellular transformation in vitro, and overexpression is associated with advanced disease across multiple tumor types. Our work provides a mechanism for the coordinate repression of let-7 miRNAs observed in a subset of human cancers, and associates activation of LIN28 and LIN28B with poor clinical prognosis.


Assuntos
Transformação Celular Neoplásica/genética , Proteínas de Ligação a DNA/genética , Regulação Neoplásica da Expressão Gênica , Neoplasias/genética , Proteínas de Ligação a RNA/genética , Animais , Carcinoma Hepatocelular/genética , Linhagem Celular Tumoral , Humanos , Neoplasias Hepáticas/genética , Camundongos , MicroRNAs/genética
15.
J Biol Chem ; 283(31): 21310-4, 2008 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-18550544

RESUMO

The developmentally regulated RNA-binding protein Lin28 blocks processing of let-7 family microRNAs (miRNAs) in embryonic cells. The molecular basis for this selective miRNA processing block is unknown. Here we find that Lin28 selectively binds the terminal loop region of let-7 precursors in vitro and that the loop mediates miRNA processing inhibition in vivo. Additionally, we identify the domains of Lin28 required for this inhibition. These findings establish a regulatory role for the terminal loop of precursors in miRNA maturation and provide insight into the mechanism by which Lin28 negatively regulates let-7 processing.


Assuntos
Regulação da Expressão Gênica , MicroRNAs/metabolismo , Proteínas de Ligação a RNA/química , Sequência de Bases , Linhagem Celular Tumoral , Humanos , Cinética , MicroRNAs/genética , Modelos Biológicos , Dados de Sequência Molecular , Mutagênese , Ligação Proteica , Estrutura Terciária de Proteína , Interferência de RNA , Homologia de Sequência do Ácido Nucleico
16.
Science ; 320(5872): 97-100, 2008 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-18292307

RESUMO

MicroRNAs (miRNAs) play critical roles in development, and dysregulation of miRNA expression has been observed in human malignancies. Recent evidence suggests that the processing of several primary miRNA transcripts (pri-miRNAs) is blocked posttranscriptionally in embryonic stem cells, embryonal carcinoma cells, and primary tumors. Here we show that Lin28, a developmentally regulated RNA binding protein, selectively blocks the processing of pri-let-7 miRNAs in embryonic cells. Using in vitro and in vivo studies, we found that Lin28 is necessary and sufficient for blocking Microprocessor-mediated cleavage of pri-let-7 miRNAs. Our results identify Lin28 as a negative regulator of miRNA biogenesis and suggest that Lin28 may play a central role in blocking miRNA-mediated differentiation in stem cells and in certain cancers.


Assuntos
Células-Tronco Embrionárias/metabolismo , MicroRNAs/metabolismo , Processamento Pós-Transcricional do RNA , Proteínas de Ligação a RNA/metabolismo , Animais , Carcinoma Embrionário , Diferenciação Celular , Linhagem Celular Transformada , Linhagem Celular Tumoral , Reprogramação Celular , Proteínas de Ligação a DNA/metabolismo , Regulação para Baixo , Células-Tronco Embrionárias/citologia , Humanos , Camundongos , Células-Tronco Pluripotentes/citologia , Células-Tronco Pluripotentes/metabolismo , Ligação Proteica , Interferência de RNA , Proteínas de Ligação a RNA/genética , Ribonuclease III/metabolismo , Transfecção , Regulação para Cima
17.
J Exp Med ; 199(4): 503-14, 2004 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-14970177

RESUMO

Kaposi's sarcoma-associated herpesvirus interleukin-6 (vIL-6) is a structural and functional homologue of the human cytokine IL-6 (hIL-6). hIL-6 and vIL-6 exhibit similar biological functions and both act via the gp130 receptor subunit to activate the Janus tyrosine kinase (JAK)1 and signal transducer and activator of transcription (STAT)1/3 pathway. Here we show that vIL-6 is N-linked glycosylated at N78 and N89 and demonstrate that N-linked glycosylation at site N89 of vIL-6 markedly enhances binding to gp130, signaling through the JAK1-STAT1/3 pathway and functions in a cytokine-dependent cell proliferation bioassay. Although hIL-6 is also N-glycosylated at N73 and multiply O-glycosylated, neither N-linked nor O-linked glycosylation is necessary for IL-6 receptor alpha-dependent binding to gp130 or signaling through JAK1-STAT1/3. As distinct from vIL-6, unglycosylated hIL-6 is as potent as glycosylated hIL-6 in stimulating B cell proliferation. These findings highlight distinct functional roles of N-linked glycosylation in viral and cellular IL-6.


Assuntos
Herpesvirus Humano 8/imunologia , Interleucina-6/imunologia , Linfócitos B/imunologia , Divisão Celular/imunologia , Linhagem Celular , Linhagem Celular Tumoral , Clonagem Molecular , Contactinas , Escherichia coli/genética , Glicosilação , Humanos , Interleucina-6/genética , Ativação Linfocitária/imunologia , Moléculas de Adesão de Célula Nervosa/imunologia , Fragmentos de Peptídeos/química , Plasmídeos , Proteínas Recombinantes/imunologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...