Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 10.768
Filtrar
1.
Adv Exp Med Biol ; 1232: 271-276, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31893420

RESUMO

Adaptation to hypoxia is essential for regulating the survival and functions of hypoxic cells; it is mainly mediated by the hypoxia-inducible factor 1 (HIF1). The alpha subunit of HIF1 (HIF1α) is a well-known regulatory component of HIF1, which is tightly controlled by various types of HIF1α-regulating processes. Previous research has shown that microtubule-regulated HIF1α nuclear translocation is a key factor for HIF1 activation under hypoxia. In this review, we summarize experimental reports on the role of microtubule-associated factors, such as microtubule, dynein, and dynein adaptor protein, in nuclear translocation of HIF1α. Based upon scientific evidence, we propose a bicaudal D homolog (BICD) as a novel HIF1α translocation regulating factor. A deeper understanding of the mechanism of the action of regulatory factors in controlling HIF1α nuclear translocation will provide novel insights into cell biology under hypoxia.


Assuntos
Transporte Ativo do Núcleo Celular , Subunidade alfa do Fator 1 Induzível por Hipóxia , Transporte Ativo do Núcleo Celular/genética , Hipóxia Celular/fisiologia , Núcleo Celular/metabolismo , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Microtúbulos/metabolismo , Transporte Proteico/genética
3.
Expert Opin Investig Drugs ; 29(1): 15-21, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31847605

RESUMO

Introduction: Selinexor is a first-in-class, oral therapeutic that selectively inhibits nuclear export. It has received fast track designation from the FDA for the treatment of relapsed or refractory diffuse large B-cell lymphoma (DLBCL) recently, and continues to be evaluated as a potential treatment for DLBCL.Area covered: This article reviews the available data from clinical trials regarding the efficacy of selinexor in DLBCL and highlights the key toxicity issues and how they may best be managed. Ongoing and future studies in DLBCL are also discussed.Expert opinion: More translational studies are necessary to leverage the unique mechanism action and rationally inform the use of selinexor in combination strategies. There are several different genetic subtypes of DLBCL, but it is not clear if these classifications will identify patients that may benefit from targeted therapies. The broad potential mechanism of action of selinexor will require careful analysis to inform predictive or prognostic biomarkers. Further evaluation of selinexor in combination with standard lymphoma regimens could identify deliverable promising regimens. Future randomized trials are key for registration and to determine the optimal role for this first-in-class agent.


Assuntos
Antineoplásicos/administração & dosagem , Hidrazinas/administração & dosagem , Linfoma Difuso de Grandes Células B/tratamento farmacológico , Triazóis/administração & dosagem , Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Animais , Antineoplásicos/efeitos adversos , Antineoplásicos/farmacologia , Biomarcadores Tumorais/metabolismo , Humanos , Hidrazinas/efeitos adversos , Hidrazinas/farmacologia , Linfoma Difuso de Grandes Células B/patologia , Terapia de Alvo Molecular , Triazóis/efeitos adversos , Triazóis/farmacologia
4.
Nat Commun ; 10(1): 4027, 2019 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-31492837

RESUMO

Cells feel the forces exerted on them by the surrounding extracellular matrix (ECM) environment and respond to them. While many cell fate processes are dictated by these forces, which are highly synchronized in space and time, abnormal force transduction is implicated in the progression of many diseases (muscular dystrophy, cancer). However, material platforms that enable transient, cyclic forces in vitro to recreate an in vivo-like scenario remain a challenge. Here, we report a hydrogel system that rapidly beats (actuates) with spatio-temporal control using a near infra-red light trigger. Small, user-defined mechanical forces (~nN) are exerted on cells growing on the hydrogel surface at frequencies up to 10 Hz, revealing insights into the effect of actuation on cell migration and the kinetics of reversible nuclear translocation of the mechanosensor protein myocardin related transcription factor A, depending on the actuation amplitude, duration and frequency.


Assuntos
Movimento Celular , Matriz Extracelular/metabolismo , Fibroblastos/metabolismo , Hidrogéis/metabolismo , Mecanotransdução Celular , Actinas/metabolismo , Transporte Ativo do Núcleo Celular , Animais , Linhagem Celular , Núcleo Celular/metabolismo , Citoesqueleto/metabolismo , Fibroblastos/citologia , Cinética , Camundongos , Transativadores/metabolismo
5.
Cell Physiol Biochem ; 53(2): 366-387, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31385665

RESUMO

BACKGROUND/AIMS: The extracellular signal-regulated kinases (ERK) 1 and 2 (ERK1/2) are members of the mitogen-activated protein kinase (MAPK) family. Upon stimulation, these kinases translocate from the cytoplasm to the nucleus, where they induce physiological processes such as proliferation and differentiation. The mechanism of translocation of this kinase involves phosphorylation of two Ser residues within a nuclear translocation signal (NTS), which allows binding to importin7 and a subsequent penetration via nuclear pores. However, the regulation of this process and the protein kinases involved are not yet clear. METHODS: To answer this point we developed specific anti phospho-SPS antibody, used this and other antibodies in Western blots and crystalized the phospho-mimetic mutated ERK. RESULTS: Here we show that the phosphorylation of both Ser residues is mediated mainly by casein kinase 2 (CK2) and that active ERK may assist in the phosphorylation of the N-terminal Ser. We also demonstrate that the phosphorylation is dependent on the release of ERK from cytoplasmic anchoring proteins. Crystal structure of the phosphomimetic ERK revealed that the NTS phosphorylation creates an acidic patch in ERK. Our model is that in resting cells ERK is bound to cytoplasmic anchors, which prevent its NTS phosphorylation. Upon stimulation, phosphorylation of the ERK TEY domain releases ERK and allows phosphorylation of its NTS by CK2 and active ERK to generate a negatively charged patch in ERK, binding to importin 7 and nuclear translocation. CONCLUSION: These results provide an important role of CK2 in regulating nuclear ERK activities.


Assuntos
Núcleo Celular/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Transporte Ativo do Núcleo Celular , Caseína Quinase II/metabolismo , Linhagem Celular , Humanos , Carioferinas/metabolismo , Fosforilação , Ligação Proteica , Receptores Citoplasmáticos e Nucleares/metabolismo
6.
Genes Dev ; 33(17-18): 1252-1264, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31395740

RESUMO

Although MAX is regarded as an obligate dimerization partner for MYC, its function in normal development and neoplasia is poorly defined. We show that B-cell-specific deletion of Max has a modest effect on B-cell development but completely abrogates Eµ-Myc-driven lymphomagenesis. While Max loss affects only a few hundred genes in normal B cells, it leads to the global down-regulation of Myc-activated genes in premalignant Eµ-Myc cells. We show that the balance between MYC-MAX and MNT-MAX interactions in B cells shifts in premalignant B cells toward a MYC-driven transcriptional program. Moreover, we found that MAX loss leads to a significant reduction in MYC protein levels and down-regulation of direct transcriptional targets, including regulators of MYC stability. This phenomenon is also observed in multiple cell lines treated with MYC-MAX dimerization inhibitors. Our work uncovers a layer of Myc autoregulation critical for lymphomagenesis yet partly dispensable for normal development.


Assuntos
Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Carcinogênese/genética , Regulação Neoplásica da Expressão Gênica , Linfoma/genética , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Transporte Ativo do Núcleo Celular , Animais , Carcinogênese/efeitos dos fármacos , Linhagem Celular Tumoral , Inibidores Enzimáticos/farmacologia , Deleção de Genes , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Indóis/farmacologia , Cinurenina/genética , Cinurenina/metabolismo , Linfoma/fisiopatologia , Camundongos , Organoides/crescimento & desenvolvimento , Organoides/fisiopatologia , Oximas/farmacologia , Sulfonamidas/farmacologia
7.
Genes Dev ; 33(17-18): 1208-1220, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31416967

RESUMO

The PIWI-interacting RNA (piRNA) pathway is a conserved small RNA-based immune system that protects animal germ cell genomes from the harmful effects of transposon mobilization. In Drosophila ovaries, most piRNAs originate from dual-strand clusters, which generate piRNAs from both genomic strands. Dual-strand clusters use noncanonical transcription mechanisms. Although transcribed by RNA polymerase II, cluster transcripts lack splicing signatures and poly(A) tails. mRNA processing is important for general mRNA export mediated by nuclear export factor 1 (Nxf1). Although UAP56, a component of the transcription and export complex, has been implicated in piRNA precursor export, it remains unknown how dual-strand cluster transcripts are specifically targeted for piRNA biogenesis by export from the nucleus to cytoplasmic processing centers. Here we report that dual-strand cluster transcript export requires CG13741/Bootlegger and the Drosophila nuclear export factor family protein Nxf3. Bootlegger is specifically recruited to piRNA clusters and in turn brings Nxf3. We found that Nxf3 specifically binds to piRNA precursors and is essential for their export to piRNA biogenesis sites, a process that is critical for germline transposon silencing. Our data shed light on how dual-strand clusters compensate for a lack of canonical features of mature mRNAs to be specifically exported via Nxf3, ensuring proper piRNA production.


Assuntos
Transporte Ativo do Núcleo Celular/genética , Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Precursores de RNA/metabolismo , RNA Interferente Pequeno/metabolismo , Proteínas de Ligação a RNA/metabolismo , Animais , Elementos de DNA Transponíveis/genética , Drosophila/genética , Proteínas de Drosophila/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Transporte Nucleocitoplasmático/genética , Proteínas de Ligação a RNA/genética
8.
RNA ; 25(11): 1549-1560, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31439809

RESUMO

The ribosomal protein Rpl1 (uL1 in universal nomenclature) is essential in yeast and constitutes part of the L1 stalk which interacts with E site ligands on the ribosome. Structural studies of nascent pre-60S complexes in yeast have shown that a domain of the Crm1-dependent nuclear export adapter Nmd3, binds in the E site and interacts with Rpl1, inducing closure of the L1 stalk. Based on this observation, we decided to reinvestigate the role of the L1 stalk in nuclear export of pre-60S subunits despite previous work showing that Rpl1-deficient ribosomes are exported from the nucleus and engage in translation. Large cargoes, such as ribosomal subunits, require multiple export factors to facilitate their transport through the nuclear pore complex. Here, we show that pre-60S subunits lacking Rpl1 or truncated for the RNA of the L1 stalk are exported inefficiently. Surprisingly, this is not due to a measurable defect in the recruitment of Nmd3 but appears to result from inefficient recruitment of the Mex67-Mtr2 heterodimer.


Assuntos
Transporte Ativo do Núcleo Celular , Subunidades Ribossômicas Maiores/metabolismo , Saccharomyces cerevisiae/metabolismo , Núcleo Celular/metabolismo , Dimerização , Proteínas de Saccharomyces cerevisiae/metabolismo
9.
Nat Commun ; 10(1): 3827, 2019 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-31444357

RESUMO

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of unknown etiology. Although defects in nucleocytoplasmic transport (NCT) may be central to the pathogenesis of ALS and other neurodegenerative diseases, the molecular mechanisms modulating the nuclear pore function are still largely unknown. Here we show that genetic and pharmacological modulation of actin polymerization disrupts nuclear pore integrity, nuclear import, and downstream pathways such as mRNA post-transcriptional regulation. Importantly, we demonstrate that modulation of actin homeostasis can rescue nuclear pore instability and dysfunction caused by mutant PFN1 as well as by C9ORF72 repeat expansion, the most common mutation in ALS patients. Collectively, our data link NCT defects to ALS-associated cellular pathology and propose the regulation of actin homeostasis as a novel therapeutic strategy for ALS and other neurodegenerative diseases.


Assuntos
Actinas/metabolismo , Esclerose Amiotrófica Lateral/patologia , Neurônios Motores/patologia , Poro Nuclear/patologia , Profilinas/metabolismo , Acrilamidas/farmacologia , Actinas/ultraestrutura , Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Transporte Ativo do Núcleo Celular/genética , Esclerose Amiotrófica Lateral/genética , Biópsia , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Proteína C9orf72/genética , Proteína C9orf72/metabolismo , Linhagem Celular , Córtex Cerebral/citologia , Córtex Cerebral/patologia , Embrião de Mamíferos , Fibroblastos , Humanos , Microscopia Eletrônica de Transmissão , Neurônios Motores/citologia , Mutação , Poro Nuclear/efeitos dos fármacos , Poro Nuclear/ultraestrutura , Cultura Primária de Células , Profilinas/genética , Multimerização Proteica/efeitos dos fármacos , Multimerização Proteica/genética , Pele/citologia , Pele/patologia , Tiazóis/farmacologia , Tiazolidinas/farmacologia
10.
J Toxicol Sci ; 44(8): 535-542, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31378764

RESUMO

Spinocerebellar ataxia type 3 (SCA3) is caused by the expansion of a glutamine-encoding CAG repeat in the ATXN3 gene encoding the protein ataxin-3. The nuclear presence of polyglutamine-expanded ataxin-3 is of critical importance for the pathogenesis of SCA3. Disulfiram, an FDA-approved drug for alcoholism, has also garnered attention in cancer treatment. However, it has shown toxicity in the nervous system. Bearing this in mind, we treated cells expressing ataxin-3 with disulfiram to measure several pathogenic cascades of SCA3, including aggregate formation, soluble ataxin-3 expression and nuclear localization of ataxin-3 and the cytotoxicity, which assess the direct effect of disulfiram on SCA3 cell models. To our knowledge, this is direct evidence that disulfiram elevated the nuclear localization of polyglutamine-expanded ataxin-3 and enhanced the cytotoxicity in a cell model of SCA3. Furthermore, disulfiram did not affect the aggregate formation of polyglutamine-expanded ataxin-3 at least at a single dose. Our findings repurpose disulfiram as a modulator of ataxin-3 nuclear transport that aggravates the pathology of SCA3, which is a new target for disulfiram. This study also represents an important example of determining novel side effects in pre-existing drugs. This study suggests that caution may be warranted when this compound is used to treat alcohol abuse or cancer in patients carrying a SCA3-causing mutation.


Assuntos
Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Dissuasores de Álcool/farmacologia , Dissuasores de Álcool/toxicidade , Ataxina-3/metabolismo , Dissulfiram/farmacologia , Dissulfiram/toxicidade , Doença de Machado-Joseph/etiologia , Dissuasores de Álcool/efeitos adversos , Dissulfiram/efeitos adversos , Células HEK293 , Humanos , Doença de Machado-Joseph/genética
11.
Chem Commun (Camb) ; 55(65): 9649-9652, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31339160

RESUMO

Intracellular delivery of bioactive polyphenols is currently evaluated as a protective strategy for cells under pharmaceutical stress. To this end, the 20mer R5 peptide from the marine diatom C. fusiformis was N-terminally modified with a quercetin derivative. This polyphenol-peptide conjugate was used to generate homogeneous silica particles under biomimetic conditions that are efficiently taken up by eukaryotic cells without being cytotoxic. However, not only was accumulation in the cytoplasm of living cells observed via electron and fluorescence microscopy but also translocation into the nucleus. The latter was only seen when the quercetin-peptide conjugate was present within the silica particles and provides a novel targeting option for silica particles to nuclei.


Assuntos
Núcleo Celular/metabolismo , Corantes Fluorescentes/farmacocinética , Fragmentos de Peptídeos/farmacocinética , Quercetina/análogos & derivados , Quercetina/farmacocinética , Dióxido de Silício/farmacocinética , Transporte Ativo do Núcleo Celular , Biomimética , Diatomáceas/química , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/química , Corantes Fluorescentes/toxicidade , Células HT29 , Humanos , Fragmentos de Peptídeos/síntese química , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/toxicidade , Quercetina/síntese química , Quercetina/toxicidade , Dióxido de Silício/química , Dióxido de Silício/toxicidade
12.
Mol Med Rep ; 20(3): 2227-2235, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31322210

RESUMO

Elevated plasma homocysteine (Hcy), known as hyperhomocysteinemia (HHcy), is an independent risk factor for neurodegenerative diseases. Hcy, even at a low concentration, can promote free radical formation and increase oxidative stress, leading to neuronal death, which may be an important mechanism underlying the pathogenesis of neurodegenerative diseases. Although several reports have indicated that the nuclear translocation of glyceraldehyde 3­phosphate dehydrogenase (GAPDH) may be involved in Hcy­induced apoptosis, the exact mechanism remains to be fully elucidated. The siah E3 ubiquitin protein ligase 1 (siah­1) gene was found to be critical for the translocation of GAPDH from the cytoplasm to the nucleus. In the present study, the role of siah­1 was investigated in the nuclear translocation of GAPDH in rat C6 astroglioma cells treated with Hcy. C6 cells were treated with various concentrations of Hcy for 48 h and the expression level of siah­1 was examined using reverse transcription­quantitative polymerase chain reaction and western blotting analysis. In addition, the subcellular localization of siah­1 and GAPDH and the interaction between these two factors were investigated by immunofluorescence staining and co­immunoprecipitation assay, respectively. The results showed that Hcy at a high concentration increased the expression of siah­1 and induced nuclear translocation of siah­1 and GAPDH. In addition, siah­1 knockdown by siah­1 small interfering RNA significantly decreased the Hcy­induced nuclear accumulation of GAPDH and inhibited the impairment of C6 cells. These findings suggest that siah­1 is involved in Hcy­induced cell damage by promoting the nuclear translocation of GAPDH.


Assuntos
Astrocitoma/metabolismo , Núcleo Celular/metabolismo , Gliceraldeído-3-Fosfato Desidrogenases/metabolismo , Homocisteína/metabolismo , Proteínas Nucleares/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Transporte Ativo do Núcleo Celular , Animais , Astrocitoma/patologia , Linhagem Celular Tumoral , Ratos
13.
J Exp Clin Cancer Res ; 38(1): 296, 2019 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-31288861

RESUMO

BACKGROUND: Karyopherin nuclear transport receptors play important roles in tumour development and drug resistance and have been reported as potential biomarkers and therapeutic targets for tumour treatment. However, IPO5, one of the karyopherin nuclear transport receptor family members, remains largely uncharacterized in tumour progression. METHODS: The TCGA data, quantitative reverse transcription-PCR (qRT-PCR), western blotting, and IHC analyses were used to detect IPO5 expression in CRC tissues. A series of in vivo and in vitro experiments was utilized to demonstrate the function of IPO5 in CRC tissues. Mass spectrometry (MS), CO-IP technology, subcellular fractionation, and immunofluorescence were utilized to investigate the possible mechanisms of CRC. RESULTS: IPO5 was highly expressed and positively correlated with the clinicopathological characteristics of colorectal cancer tissues. Functional experiments indicated that IPO5 could promote the development of CRC. Mechanistically, we screened RASAL2, one cargo of IPO5, and further confirmed that IPO5 bound to the NLS sequence of RASAL2, mediating RASAL2 nuclear translocation and inducing RAS signal activation, thereby promoting the progression of CRC. CONCLUSIONS: Together, our results indicate that IPO5 is overexpressed in colorectal cancer cells. By transporting RASAL2, IPO5 may play a crucial role in CRC.


Assuntos
Proteínas de Transporte/metabolismo , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Neoplasias Colorretais/genética , Neoplasias Colorretais/metabolismo , beta Carioferinas/genética , beta Carioferinas/metabolismo , Transporte Ativo do Núcleo Celular , Adulto , Idoso , Animais , Proteínas de Transporte/química , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Neoplasias Colorretais/patologia , Modelos Animais de Doenças , Resistencia a Medicamentos Antineoplásicos/genética , Feminino , Fluoruracila/farmacologia , Xenoenxertos , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Modelos Biológicos , Gradação de Tumores , Metástase Neoplásica , Estadiamento de Neoplasias , Sinais de Localização Nuclear , Ligação Proteica , Carga Tumoral
14.
Int J Biol Macromol ; 137: 657-665, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31276719

RESUMO

To characterize the immuno-stimulating ingredient from the Korean citrus, Cheongkyool, a crude polysaccharide (CCE-0) was isolated from the pectinase digests of Cheongkyool peels, from which the complex polysaccharide CCE-I was purified to homogeneity by gel filtration. CCE-I highly enhanced the production of IL-6, TNF-α, and NO in RAW 264.7 cell lines. It augmented the mRNA expression of IL-6, TNF-α, and iNOS in a dose-dependent manner. Moreover, CCE-I dose-dependently induced phosphorylation of MAPKs and NF-κB related proteins and led to the nuclear translocation of p65. The effect of CCE-I on NO and IL-6 production was suppressed by treatment with specific antibodies for TLR2, TLR4, and scavenger receptors. Conversely, the primary structure of CCE-I that exhibited potent immunostimulatory activity was characterized by sugar composition, linkage analysis, and oligosaccharide analysis after ß-elimination. The results suggested that CCE-I may be a rhamnogalacturonan-I type, highly branched polysaccharide with short arabinan and galactan side chains.


Assuntos
Citrus/química , Ativação de Macrófagos/efeitos dos fármacos , Pectinas/química , Polissacarídeos/química , Polissacarídeos/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Animais , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Interleucina-6/genética , Espaço Intracelular/efeitos dos fármacos , Espaço Intracelular/metabolismo , Metilação , Camundongos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Óxido Nítrico/metabolismo , Fosforilação/efeitos dos fármacos , Células RAW 264.7 , Fator de Necrose Tumoral alfa/genética
15.
Nat Microbiol ; 4(10): 1671-1679, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31263181

RESUMO

Influenza viruses antagonize key immune defence mechanisms via the virulence factor non-structural protein 1 (NS1). A key mechanism of virulence by NS1 is blocking nuclear export of host messenger RNAs, including those encoding immune factors1-3; however, the direct cellular target of NS1 and the mechanism of host mRNA export inhibition are not known. Here, we identify the target of NS1 as the mRNA export receptor complex, nuclear RNA export factor 1-nuclear transport factor 2-related export protein 1 (NXF1-NXT1), which is the principal receptor mediating docking and translocation of mRNAs through the nuclear pore complex via interactions with nucleoporins4,5. We determined the crystal structure of NS1 in complex with NXF1-NXT1 at 3.8 Å resolution. The structure reveals that NS1 prevents binding of NXF1-NXT1 to nucleoporins, thereby inhibiting mRNA export through the nuclear pore complex into the cytoplasm for translation. We demonstrate that a mutant influenza virus deficient in binding NXF1-NXT1 does not block host mRNA export and is attenuated. This attenuation is marked by the release of mRNAs encoding immune factors from the nucleus. In sum, our study uncovers the molecular basis of a major nuclear function of influenza NS1 protein that causes potent blockage of host gene expression and contributes to inhibition of host immunity.


Assuntos
Núcleo Celular/metabolismo , Vírus da Influenza A/fisiologia , Influenza Humana/metabolismo , RNA Mensageiro/metabolismo , Proteínas não Estruturais Virais/metabolismo , Células A549 , Transporte Ativo do Núcleo Celular , Sítios de Ligação , Células Cultivadas , Cristalografia por Raios X , Humanos , Vírus da Influenza A/genética , Vírus da Influenza A/metabolismo , Modelos Moleculares , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Complexo de Proteínas Formadoras de Poros Nucleares/química , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Proteínas de Transporte Nucleocitoplasmático/química , Proteínas de Transporte Nucleocitoplasmático/genética , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Ligação Proteica , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Proteínas não Estruturais Virais/genética
16.
Cells ; 8(6)2019 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-31181773

RESUMO

Protein nuclear transport is an integral process to many cellular pathways and often plays a critical role during viral infection. To overcome the barrier presented by the nuclear membrane and gain access to the nucleus, virally encoded proteins have evolved ways to appropriate components of the nuclear transport machinery. By binding karyopherins, or the nuclear pore complex, viral proteins influence their own transport as well as the transport of key cellular regulatory proteins. This review covers how viral proteins can interact with different components of the nuclear import machinery and how this influences viral replicative cycles. We also highlight the effects that viral perturbation of nuclear transport has on the infected host and how we can exploit viruses as tools to study novel mechanisms of protein nuclear import. Finally, we discuss the possibility that drugs targeting these transport pathways could be repurposed for treating viral infections.


Assuntos
Transporte Ativo do Núcleo Celular/fisiologia , Poro Nuclear/metabolismo , Vírus/patogenicidade , Interações Hospedeiro-Patógeno , Humanos , Carioferinas/metabolismo , Transporte Proteico , Replicação Viral , Vírus/metabolismo
17.
PLoS Genet ; 15(6): e1008061, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31170156

RESUMO

The nuclear pore complex (NPC) forms a gateway for nucleocytoplasmic transport. The outer ring protein complex of the NPC (the Nup107-160 subcomplex in humans) is a key component for building the NPC. Nup107-160 subcomplexes are believed to be symmetrically localized on the nuclear and cytoplasmic sides of the NPC. However, in S. pombe immunoelectron and fluorescence microscopic analyses revealed that the homologous components of the human Nup107-160 subcomplex had an asymmetrical localization: constituent proteins spNup132 and spNup107 were present only on the nuclear side (designated the spNup132 subcomplex), while spNup131, spNup120, spNup85, spNup96, spNup37, spEly5 and spSeh1 were localized only on the cytoplasmic side (designated the spNup120 subcomplex), suggesting the complex was split into two pieces at the interface between spNup96 and spNup107. This contrasts with the symmetrical localization reported in other organisms. Fusion of spNup96 (cytoplasmic localization) with spNup107 (nuclear localization) caused cytoplasmic relocalization of spNup107. In this strain, half of the spNup132 proteins, which interact with spNup107, changed their localization to the cytoplasmic side of the NPC, leading to defects in mitotic and meiotic progression similar to an spNup132 deletion strain. These observations suggest the asymmetrical localization of the outer ring spNup132 and spNup120 subcomplexes of the NPC is necessary for normal cell cycle progression in fission yeast.


Assuntos
Complexo de Proteínas Formadoras de Poros Nucleares/genética , Poro Nuclear/genética , Proteínas de Schizosaccharomyces pombe/genética , Transporte Ativo do Núcleo Celular/genética , Ciclo Celular/genética , Divisão Celular/genética , Núcleo Celular/genética , Núcleo Celular/ultraestrutura , Citoplasma/genética , Citoplasma/ultraestrutura , Humanos , Meiose/genética , Microscopia de Fluorescência , Membrana Nuclear/genética , Poro Nuclear/ultraestrutura , Ligação Proteica/genética , Saccharomyces cerevisiae/genética , Schizosaccharomyces/genética
18.
Endocrinology ; 160(8): 1999-2014, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31188427

RESUMO

Gonadotropin secretion, which is elicited by GnRH stimulation of the anterior pituitary gonadotropes, is a critical feature of reproductive control and the maintenance of fertility. In addition, activation of the GnRH receptor (GnRHR) regulates transcription and translation of multiple factors that regulate the signaling response and synthesis of gonadotropins. GnRH stimulation results in a broad redistribution of mRNA between active and inactive polyribosomes within the cell, but the mechanism of redistribution is not known. The RNA-binding protein embryonic lethal, abnormal vision, Drosophila-like 1 (ELAVL1) binds to AU-rich elements in mRNA and is one of the most abundant mRNA-binding proteins in eukaryotic cells. It is known to serve as a core component of RNA-binding complexes that direct the fate of mRNA. In LßT2 gonadotropes, we showed that ELAVL1 binds to multiple mRNAs encoding factors that are crucial for gonadotropin synthesis and release. Association with some mRNAs is GnRH sensitive but does not correlate with abundance of binding. We also showed MAPK-dependent changes in intracellular localization of ELAVL1 in response to GnRH stimulation. Knockdown of ELAVL1 gene expression resulted in reduced Lhb and Gnrhr mRNA levels, reduced cell surface expression of GnRHR, and reduced LH secretion in response to GnRH stimulation. Overall, these observations not only support the role of ELAVL1 in GnRHR-mediated regulation of gene expression and LH secretion but also indicate that other factors may contribute to the precise fate of mRNA in response to GnRH stimulation of gonadotropes.


Assuntos
Proteína Semelhante a ELAV 1/fisiologia , Hormônio Liberador de Gonadotropina/farmacologia , Receptores LHRH/genética , Transporte Ativo do Núcleo Celular , Animais , Células Cultivadas , MAP Quinases Reguladas por Sinal Extracelular/fisiologia , Feminino , Regulação da Expressão Gênica , Hormônio Luteinizante/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , RNA Mensageiro/metabolismo
19.
Int J Biol Macromol ; 136: 27-34, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31185242

RESUMO

Lactobacillus acidophilus NCFM, a probiotic generally regarded as safe, carries a proteinaceous surface (S) layer, composed of numerous identical subunits (surface layer protein, Slp). S-layer proteins have been confirmed to possess multiple biological properties, but their role in maintaining the intestinal epithelial barrier is not fully known. We investigated the effects of Slp on tumor necrosis factor (TNF)-α-elicited intestinal barrier dysfunction and explored the underlying molecular mechanism. TNF-α administration markedly induced intestinal epithelial injury and inflammation in Caco-2 cells. Preincubation of Caco-2 cells with Slp at concentrations ranging from 50 to 100 µg/mL for 6 h improved intestinal epithelial cell integrity and permeability, restored ZO-1 and Occludin protein expressions (P < 0.05) and reduced the secretion of interleukin 8 by a maximum of 47.8%. Furthermore, the addition of Slp to Caco-2 cell monolayers attenuated cell apoptosis and inhibited nuclear factor-κB (NF-κB) p65 nucleus translocation by suppressing the activation of NF-κB. Collectively, the ability of Slp to attenuate dysfunction of the intestinal epithelial barrier stimulated by TNF-α and to exert anti-inflammatory effects supports its potential use in the development of functional foods and in the prevention of inflammatory bowel diseases.


Assuntos
Proteínas de Bactérias/farmacologia , Mucosa Intestinal/efeitos dos fármacos , Lactobacillus acidophilus , Glicoproteínas de Membrana/farmacologia , Fator de Necrose Tumoral alfa/farmacologia , Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Proteínas de Bactérias/uso terapêutico , Células CACO-2 , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Inflamação/tratamento farmacológico , Interleucina-8/metabolismo , Mucosa Intestinal/citologia , Mucosa Intestinal/metabolismo , Glicoproteínas de Membrana/uso terapêutico , Permeabilidade/efeitos dos fármacos , Proteínas de Junções Íntimas/metabolismo , Fator de Transcrição RelA/metabolismo
20.
Toxicol Lett ; 313: 108-119, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31251971

RESUMO

Polychlorinated biphenyls (PCBs) are classic persistent organic pollutants (POPs) and are associated with the progression of many cancers, including liver cancer. The present study investigated the effect of 2,3'4,4',5-pentachlorobiphenyl (PCB118) on hepatocellular carcinoma cell proliferation and its underlying mechanisms. The results indicated that PCB118 exposure promotes the proliferation and glycolysis of hepatocellular carcinoma SMMC-7721 cells. Moreover, PCB118 exposure increased the expression level of pyruvate kinase M2 (PKM2) and its nuclear translocation, whereas treatment with PKM2 shRNA suppressed the induction of cell proliferation and glycolysis by PCB118. PCB118 stimulated reactive oxygen species (ROS) production by activating nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Treatment with the antioxidants N-acetyl-L-cysteine (NAC) and superoxide dismutase (SOD) prevented PCB118-induced effects on PKM2, cell proliferation and glycolysis. Furthermore, we found that PCB118 activated NADPH oxidase through the aryl hydrocarbon receptor (AhR) in SMMC-7721 cells. Consistently, treatment with AhR shRNA suppressed PCB118-induced effects on PKM2, cell proliferation and glycolysis. Overall, these results indicated that PCB118 promotes HCC cell proliferation via PKM2-dependent upregulation of glycolysis, which is mediated by AhR/NADPH oxidase-induced ROS production.


Assuntos
Carcinógenos Ambientais/toxicidade , Carcinoma Hepatocelular/enzimologia , Proteínas de Transporte/metabolismo , Proliferação de Células/efeitos dos fármacos , Glicólise/efeitos dos fármacos , Neoplasias Hepáticas/enzimologia , Proteínas de Membrana/metabolismo , Bifenilos Policlorados/toxicidade , Hormônios Tireóideos/metabolismo , Transporte Ativo do Núcleo Celular , Fatores de Transcrição Hélice-Alça-Hélice Básicos/agonistas , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Proteínas de Transporte/genética , Linhagem Celular Tumoral , Humanos , Neoplasias Hepáticas/patologia , Proteínas de Membrana/genética , NADPH Oxidases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores de Hidrocarboneto Arílico/agonistas , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Transdução de Sinais/efeitos dos fármacos , Hormônios Tireóideos/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA