Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 51
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Plant Cell Physiol ; 65(1): 120-127, 2024 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-37856257

RESUMO

The two-component system (TCS) is a conserved signal transduction module in bacteria. The Hik2-Rre1 system is responsible for transcriptional activation upon high-temperature shift as well as plastoquinone-related redox stress in the cyanobacterium Synechococcus elongatus PCC 7942. As heat-induced de novo protein synthesis was previously shown to be required to quench the heat-activated response, we investigated the underlying mechanism in this study. We found that the heat-inducible transcription activation was alleviated by the overexpression of dnaK2, which is an essential homolog of the highly conserved HSP70 chaperone and whose expression is induced under the control of the Hik2-Rre1 TCS. Phosphorylation of Rre1 correlated with transcription of the regulatory target hspA. The redox stress response was found to be similarly repressed by dnaK2 overexpression. Considered together with the previous information, we propose a negative feedback mechanism of the Hik2-Rre1-dependent stress response that maintains the cellular homeostasis mediated by DnaK2.


Assuntos
Proteínas de Bactérias , Synechococcus , Retroalimentação , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Synechococcus/genética , Synechococcus/metabolismo , Resposta ao Choque Térmico , Proteínas de Choque Térmico HSP70/genética , Regulação Bacteriana da Expressão Gênica
2.
RNA ; 27(1): 12-26, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33028652

RESUMO

Identifying small molecules that selectively bind an RNA target while discriminating against all other cellular RNAs is an important challenge in RNA-targeted drug discovery. Much effort has been directed toward identifying drug-like small molecules that minimize electrostatic and stacking interactions that lead to nonspecific binding of aminoglycosides and intercalators to many stem-loop RNAs. Many such compounds have been reported to bind RNAs and inhibit their cellular activities. However, target engagement and cellular selectivity assays are not routinely performed, and it is often unclear whether functional activity directly results from specific binding to the target RNA. Here, we examined the propensities of three drug-like compounds, previously shown to bind and inhibit the cellular activities of distinct stem-loop RNAs, to bind and inhibit the cellular activities of two unrelated HIV-1 stem-loop RNAs: the transactivation response element (TAR) and the rev response element stem IIB (RREIIB). All compounds bound TAR and RREIIB in vitro, and two inhibited TAR-dependent transactivation and RRE-dependent viral export in cell-based assays while also exhibiting off-target interactions consistent with nonspecific activity. A survey of X-ray and NMR structures of RNA-small molecule complexes revealed that aminoglycosides and drug-like molecules form hydrogen bonds with functional groups commonly accessible in canonical stem-loop RNA motifs, in contrast to ligands that specifically bind riboswitches. Our results demonstrate that drug-like molecules can nonspecifically bind stem-loop RNAs most likely through hydrogen bonding and electrostatic interactions and reinforce the importance of assaying for off-target interactions and RNA selectivity in vitro and in cells when assessing novel RNA-binders.


Assuntos
Aminoglicosídeos/farmacologia , Genes env/efeitos dos fármacos , Repetição Terminal Longa de HIV/efeitos dos fármacos , RNA Viral/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/farmacologia , Aminoglicosídeos/química , Aminoglicosídeos/metabolismo , Pareamento de Bases , Sequência de Bases , Sítios de Ligação , Bioensaio , Descoberta de Drogas , HIV-1/efeitos dos fármacos , HIV-1/genética , HIV-1/metabolismo , Humanos , Ligação de Hidrogênio , Isoquinolinas/química , Isoquinolinas/metabolismo , Isoquinolinas/farmacologia , Conformação de Ácido Nucleico , Pentamidina/química , Pentamidina/metabolismo , Pentamidina/farmacologia , RNA Viral/genética , RNA Viral/metabolismo , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/metabolismo , Eletricidade Estática , Ativação Transcricional/efeitos dos fármacos , Ioimbina/química , Ioimbina/metabolismo , Ioimbina/farmacologia
3.
J Virol ; 96(18): e0098622, 2022 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-36069548

RESUMO

All lentiviruses encode the accessory protein Rev, whose main biological function is to mediate the nuclear export of unspliced and incompletely spliced viral transcripts by binding to a viral cis-acting element (termed the Rev-responsive element, RRE) within the env-encoding region. Equine infectious anemia virus (EIAV) is a member of the lentivirus genus in the Retroviridae family and is considered an important model for the study of lentivirus pathogenesis. Here, we identified a novel transcript from the EIAV genome that encoded a viral protein, named Mat, with an unknown function. The transcript mat was fully spliced and comprised parts of the coding regions of MA and TM. Interestingly, the expression of Mat depended on Rev and the chromosome region maintenance 1 (CRM1) pathway. Rev could specifically bind to Mat mRNA to promote its nuclear export. We further identified that the first exon of Mat mRNA, which was located within the Gag-encoding region, acted as an unreported RRE. Altogether, we identified a novel fully spliced transcript mat with an unusual RRE, which interacted with Rev for nuclear export through the CRM1 pathway. These findings updated the EIAV genome structure, highlighted the diversification of posttranscriptional regulation patterns in EIAV, and may help to expand the understanding of gene transcription and expression of lentivirus. IMPORTANCE In lentiviruses, the nuclear export of viral transcripts is an important step in controlling viral gene expression. Generally, the unspliced and incompletely spliced transcripts are exported via the CRM1-dependent export pathway in a process mediated by the viral Rev protein by binding to the Rev-responsive element (RRE) located within the Env-coding region. However, the completely spliced transcripts are exported via an endogenous cellular pathway, which was Rev independent. Here, we identified a novel fully spliced transcript from EIAV and demonstrated that it encoded a viral protein, termed Mat. Interestingly, we determined that the expression of Mat depended on Rev and identified that the first exon of Mat mRNA could specifically bind to Rev and be exported to the cytoplasm, which suggested that the first exon of Mat mRNA was a second RRE of EIAV. These findings provided important insights into the Rev-dependent nuclear export of completely spliced transcripts in lentiviruses.


Assuntos
Produtos do Gene rev , Vírus da Anemia Infecciosa Equina , Lentivirus Equinos , Animais , Produtos do Gene rev/genética , Cavalos , Vírus da Anemia Infecciosa Equina/metabolismo , Splicing de RNA , RNA Mensageiro/genética , RNA Viral/genética
4.
Epilepsia ; 64(7): 1699-1708, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37073881

RESUMO

Well-designed placebo-controlled clinical trials are critical to the development of novel treatments for epilepsy, but their design has not changed for decades. Patients, clinicians, regulators, and innovators all have concerns that recruiting for trials is challenging, in part, due to the static design of maintaining participants for long periods on add-on placebo when there are an increasing number of options for therapy. A traditional trial maintains participants on blinded treatment for a static period (e.g., 12 weeks of maintenance), during which participants on placebo have an elevated risk of sudden unexpected death in epilepsy compared to patients on an active treatment. Time-to-event trials observe participants on blinded treatment until a key event occurs (e.g., post-randomization seizure count matches pre-randomization monthly seizure count). In this article, we review the evidence for these designs based on re-analysis of prior trials, one published trial that used a time-to-second seizure design, and experience from an ongoing blinded trial. We also discuss remaining concerns regarding time-to-event trials. We conclude that, despite potential limitations, time-to-event trials are a potential promising mechanism to make trials more patient friendly and reduce placebo exposure, which are urgent needs to improve safety and increase recruitment to trials.


Assuntos
Anticonvulsivantes , Epilepsia , Humanos , Anticonvulsivantes/uso terapêutico , Epilepsia/tratamento farmacológico , Epilepsia/induzido quimicamente , Projetos de Pesquisa , Convulsões/tratamento farmacológico , Convulsões/induzido quimicamente , Ensaios Clínicos como Assunto
5.
Dokl Biol Sci ; 513(Suppl 1): S45-S50, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38472686

RESUMO

Delivery of ribonucleoprotein complexes of Cas9 nuclease and guide RNA into target cells with virus-like particles (VLP) is one of the novel methods of genome editing and is suitable for gene therapy of human diseases in the future. The efficiency of genome editing with VLPs depends on the Cas9 packaging into VLPs, the process mediated by the viral Gag protein. To improve the packaging of Cas9 into NanoMEDIC VLPs, plasmid constructs for Cas9 and Gag expression were modified by adding the HIV Rev response element (RRE), which was expected to increase the nuclear export of RRE-containing transcripts into the cytosol via the Rev accessory protein, as described for a Vpr-Cas9-based VLP system. The Cas9 and Gag protein levels in cell lysates were found to increase upon cotransfection with either the Rev-expressing plasmid or the empty control plasmid. The effect was independent of the presence of RRE in the transcript. Moreover, AP21967-induced dimerization of FRB and FKBP12, but not plasmid modification with RRE and/or cotransfection with the Rev-expressing plasmid, was shown to play the major role in Cas9 packaging into NanoMEDIC VLPs. The data indicated that it is impractical to use the RRE-Rev module to enhance the packaging of Cas9 nuclease into VLPs.


Assuntos
HIV-1 , Humanos , HIV-1/genética , Sistemas CRISPR-Cas , RNA Guia de Sistemas CRISPR-Cas , Produtos do Gene gag/genética , Elementos de Resposta
6.
Sensors (Basel) ; 22(13)2022 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-35808283

RESUMO

The Internet of things concept empowered by low-cost sensor technologies and headless computers has upscaled the applicability of vibration monitoring systems in recent years. Raspberry Shake devices are among those systems, constituting a crowdsourcing framework and forming a worldwide seismic network of over a thousand nodes. While Raspberry Shake devices have been proven to densify seismograph arrays efficiently, their potential for structural health monitoring (SHM) is still unknown and is open to discovery. This paper presents recent findings from existing buildings located in Bucharest (Romania) equipped with Raspberry Shake 4D (RS4D) devices, whose signal recorded under multiple seismic events has been analyzed using different modal identification algorithms. The obtained results show that RS4D modules can capture the building vibration behavior despite the short-duration and low-amplitude excitation sources. Based on 15 RS4D device readings from five different multistorey buildings, the results do not indicate damage in terms of modal frequency decay. The findings of this research propose a baseline for future seismic events that can track the changes in vibration characteristics as a consequence of future strong earthquakes. In summary, this research presents multi-device, multi-testbed, and multi-algorithm evidence on the feasibility of RS4D modules as SHM instruments, which are yet to be explored in earthquake engineering.


Assuntos
Terremotos , Rubus , Algoritmos , Movimento (Física) , Vibração
7.
J Virol ; 93(11)2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30867301

RESUMO

The HIV-1 Rev response element (RRE) is a cis-acting RNA element characterized by multiple stem-loops. Binding and multimerization of the HIV Rev protein on the RRE promote the nucleocytoplasmic export of incompletely spliced mRNAs, an essential step in HIV replication. Most of our understanding of the Rev-RRE regulatory axis comes from studies of lab-adapted HIV clones. However, in human infection, HIV evolves rapidly, and mechanistic studies of naturally occurring Rev and RRE sequences are essential to understanding this system. We previously described the functional activity of two RREs found in circulating viruses in a patient followed during the course of HIV infection. The early RRE was less functionally active than the late RRE, despite differing in sequence by only 4 nucleotides. In this study, we describe the sequence, function, and structural evolution of circulating RREs in this patient using plasma samples collected over 6 years of untreated infection. RRE sequence diversity varied over the course of infection, with evidence of selection pressure that led to sequence convergence as disease progressed being found. An increase in RRE functional activity was observed over time, and a key mutation was identified that correlates with a major conformational change in the RRE and increased functional activity. Additional mutations were found that may have contributed to increased activity as a result of greater Shannon entropy in RRE stem-loop II, which is key to primary Rev binding.IMPORTANCE HIV-1 replication requires interaction of the viral Rev protein with a cis-acting regulatory RNA, the Rev response element (RRE), whose sequence changes over time during infection within a single host. In this study, we show that the RRE is subject to selection pressure and that RREs from later time points in infection tend to have higher functional activity. Differences in RRE functional activity are attributable to specific changes in RNA structure. Our results suggest that RRE evolution during infection may be important for HIV pathogenesis and that efforts to develop therapies acting on this viral pathway should take this into account.


Assuntos
Genes env/genética , Genes env/fisiologia , HIV-1/metabolismo , Produtos do Gene rev/genética , Infecções por HIV/virologia , Soropositividade para HIV/genética , HIV-1/fisiologia , Humanos , Mutação , Conformação de Ácido Nucleico , Nucleotídeos/metabolismo , Ligação Proteica , RNA Mensageiro/genética , RNA Viral/genética , Elementos de Resposta/genética , Replicação Viral/genética , Produtos do Gene rev do Vírus da Imunodeficiência Humana/metabolismo , Produtos do Gene rev do Vírus da Imunodeficiência Humana/ultraestrutura
8.
Proc Natl Acad Sci U S A ; 114(39): 10420-10425, 2017 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-28893989

RESUMO

Posttranslational modification of ribosomally synthesized peptides provides an elegant means for the production of biologically active molecules known as RiPPs (ribosomally synthesized and posttranslationally modified peptides). Although the leader sequence of the precursor peptide is often required for turnover, the exact mode of recognition by the modifying enzymes remains unclear for many members of this class of natural products. Here, we have used X-ray crystallography and computational modeling to examine the role of the leader peptide in the biosynthesis of a homolog of streptide, a recently identified peptide natural product with an intramolecular lysine-tryptophan cross-link, which is installed by the radical S-adenosylmethionine (SAM) enzyme, StrB. We present crystal structures of SuiB, a close ortholog of StrB, in various forms, including apo SuiB, SAM-bound SuiB, and a complex of SuiB with SAM and its peptide substrate, SuiA. Although the N-terminal domain of SuiB adopts a typical RRE (RiPP recognition element) motif, which has been implicated in precursor peptide recognition, we observe binding of the leader peptide in the catalytic barrel rather than the N-terminal domain. Computational simulations support a mechanism in which the leader peptide guides posttranslational modification by positioning the cross-linking residues of the precursor peptide within the active site. Together the results shed light onto binding of the precursor peptide and the associated conformational changes needed for the formation of the unique carbon-carbon cross-link in the streptide family of natural products.


Assuntos
Fosfotransferases (Aceptor do Grupo Álcool)/química , S-Adenosilmetionina/química , Streptococcus/metabolismo , Biologia Computacional , Cristalografia por Raios X , Modelos Moleculares , Ligação Proteica , Biossíntese de Proteínas/fisiologia , Processamento de Proteína Pós-Traducional/fisiologia , Sinais Direcionadores de Proteínas/genética , Estrutura Secundária de Proteína , Streptococcus/enzimologia
9.
Retrovirology ; 16(1): 40, 2019 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-31842941

RESUMO

BACKGROUND: The HERV-K (HML-2) viruses are the youngest of the human endogenous retroviruses. They are present as several almost complete proviral copies and numerous fragments in the human genome. Many HERV-K proviruses express a regulatory protein Rec, which binds to an element present in HERV-K mRNAs called the RcRE. This interaction is necessary for the nucleo-cytoplasmic export and expression of HERV-K mRNAs that retain introns and plays a role analogous to that of Rev and the RRE in HIV replication. There are over 900 HERV-K RcREs distributed throughout the human genome. Thus, it was of interest to determine if Rev could functionally interact with selected RcRE elements that map either to HERV-K proviruses or human gene regions. This interaction would have the potential to alter the expression of both HERV-K mRNAs and cellular mRNAs during HIV-1 infection. RESULTS: In this study we employed a combination of RNAseq, bioinformatics and cell-based functional assays. Potential RcREs were identified through a number of bioinformatic approaches. They were then tested for their ability to promote export and translation of a reporter mRNA with a retained intron in conjunction with Rev or Rec. Some of the selected elements functioned well with either Rev, Rec or both, whereas some showed little or no function. Rev function on individual RcREs varied and was also dependent on the Rev sequence. We also performed RNAseq on total and cytoplasmic RNA isolated from SupT1 cells expressing HIV Rev, with or without Tat, or HERV-K Rec. Proviral mRNA from three HERV-K loci (4p16.1b, 22q11.23 and most significantly 3q12.3) accumulated in the cytoplasm in the presence of Rev or Tat and Rev, but not Rec. Consistent with this, the 3' RcRE from 3q12.3 functioned well with HIV-Rev in our reporter assay. In contrast, this RcRE showed little or no function with Rec. CONCLUSIONS: The HIV Rev protein can functionally interact with many RcREs present in the human genome, depending on the RcRE sequence, as well as the Rev sequence. This leads to export of some of the HERV-K proviral mRNAs and also has the potential to change the expression of non-viral genes.


Assuntos
Retrovirus Endógenos/genética , Genoma Humano , HIV-1/genética , Provírus/genética , Produtos do Gene rev do Vírus da Imunodeficiência Humana/metabolismo , Regulação Viral da Expressão Gênica , Células HEK293 , Humanos , RNA Viral/genética , Produtos do Gene rev do Vírus da Imunodeficiência Humana/genética
10.
Bioorg Med Chem Lett ; 29(2): 339-341, 2019 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-30477891

RESUMO

Synthetic neamine mimetics have been evaluated for binding to the HIV-1 Rev response element. Modified neamine derivatives, obtained from reductive amination of neamine, led to identification of new 6-amino modified neamine-type ligands with HIV-1 RRE binding affinity up to 20× that of neamine and up to 6× that of the more complex neomycin itself. This provides a noteworthy structure-activity increase and a useful lead to simplified, chemically accessible mimetics.


Assuntos
Fármacos Anti-HIV/farmacologia , Framicetina/farmacologia , HIV-1/efeitos dos fármacos , Neomicina/farmacologia , RNA Viral/efeitos dos fármacos , Elementos de Resposta/efeitos dos fármacos , Fármacos Anti-HIV/síntese química , Fármacos Anti-HIV/química , Relação Dose-Resposta a Droga , Framicetina/síntese química , Framicetina/química , Estrutura Molecular , Neomicina/análogos & derivados , Neomicina/química , Relação Estrutura-Atividade
11.
Bioorg Med Chem ; 27(8): 1759-1765, 2019 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-30879859

RESUMO

Interaction of HIV-1 rev response element (RRE) RNA with its cognate protein, Rev, is critical for HIV-1 replication. Understanding the mode of interaction between RRE RNA and ligands at the binding site can facilitate RNA molecular recognition as well as provide a strategy for developing anti-HIV therapeutics. Our approach utilizes branched peptides as a scaffold for multivalent binding to RRE IIB (high affinity rev binding site) with incorporation of unnatural amino acids to increase affinity via non-canonical interactions with the RNA. Previous high throughput screening of a 46,656-member library revealed several hits that bound RRE IIB RNA in the sub-micromolar range. In particular, the lead compound, 4B3, displayed a Kd value of 410 nM and demonstrated selectivity towards RRE. A ribonuclease protection assay revealed that 4B3 binds to the stem-loop structure of RRE IIB RNA, which was confirmed by SHAPE analysis with 234 nt long NL4-3 RRE RNA. Our studies further indicated interaction of 4B3 with both primary and secondary Rev binding sites.


Assuntos
HIV-1/genética , Peptídeos/química , RNA Viral/química , Elementos de Resposta/genética , Sítios de Ligação , Humanos , Conformação de Ácido Nucleico , Peptídeos/síntese química , Peptídeos/metabolismo , Ligação Proteica , RNA Viral/metabolismo , Ribonucleases/química , Ribonucleases/metabolismo
12.
J Struct Biol ; 203(2): 102-108, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29605570

RESUMO

HIV-1 Rev mediates the nuclear export of unspliced and partially-spliced viral transcripts for the production of progeny genomes and structural proteins. In this process, four (or more) copies of Rev assemble onto a highly-structured 351-nt region in such viral transcripts, the Rev response element (RRE). How this occurs is not known. The Rev assembly domain has a helical-hairpin structure which associates through three (A-A, B-B and C-C) interfaces. The RRE has the topology of an upper-case letter A, with the two known Rev binding sites mapping onto the legs of the A. We have determined a crystal structure for the Rev assembly domain at 2.25 Šresolution, without resort to either mutations or chaperones. It shows that B-B dimers adopt an arrangement reversed relative to that previously reported, and join through a C-C interface to form tetramers. The new subunit arrangement shows how four Rev molecules can assemble on the two sites on the RRE to form the specificity checkpoint, and how further copies add through A-A interactions. Residues at the C-C interface, specifically the Pro31-Trp45 axis, are a potential target for intervention.


Assuntos
Genes env/fisiologia , HIV-1/genética , HIV-1/metabolismo , RNA Viral/metabolismo , Transporte Ativo do Núcleo Celular/genética , Transporte Ativo do Núcleo Celular/fisiologia , Sítios de Ligação/genética , Sítios de Ligação/fisiologia , Genes env/genética , Ligação Proteica/genética , Ligação Proteica/fisiologia , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Splicing de RNA/genética , Splicing de RNA/fisiologia , RNA Viral/genética
13.
J Virol ; 91(6)2017 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-28053097

RESUMO

Full-length unspliced human immunodeficiency virus type 1 (HIV-1) RNAs serve dual roles in the cytoplasm as mRNAs encoding the Gag and Gag-Pol capsid proteins as well as genomic RNAs (gRNAs) packaged by Gag into virions undergoing assembly at the plasma membrane (PM). Because Gag is sufficient to drive the assembly of virus-like particles even in the absence of gRNA binding, whether viral RNA trafficking plays an active role in the native assembly pathway is unknown. In this study, we tested the effects of modulating the cytoplasmic abundance or distribution of full-length viral RNAs on Gag trafficking and assembly in the context of single cells. Increasing full-length viral RNA abundance or distribution had little-to-no net effect on Gag assembly competency when provided in trans In contrast, artificially tethering full-length viral RNAs or surrogate gag-pol mRNAs competent for Gag synthesis to non-PM membranes or the actin cytoskeleton severely reduced net virus particle production. These effects were explained, in large part, by RNA-directed changes to Gag's distribution in the cytoplasm, yielding aberrant subcellular sites of virion assembly. Interestingly, RNA-dependent disruption of Gag trafficking required either of two cis-acting RNA regulatory elements: the 5' packaging signal (Psi) bound by Gag during genome encapsidation or, unexpectedly, the Rev response element (RRE), which regulates the nuclear export of gRNAs and other intron-retaining viral RNAs. Taken together, these data support a model for native infection wherein structural features of the gag-pol mRNA actively compartmentalize Gag to preferred sites within the cytoplasm and/or PM.IMPORTANCE The spatial distribution of viral mRNAs within the cytoplasm can be a crucial determinant of efficient translation and successful virion production. Here we provide direct evidence that mRNA subcellular trafficking plays an important role in regulating the assembly of human immunodeficiency virus type 1 (HIV-1) virus particles at the plasma membrane (PM). Artificially tethering viral mRNAs encoding Gag capsid proteins (gag-pol mRNAs) to distinct non-PM subcellular locales, such as cytoplasmic vesicles or the actin cytoskeleton, markedly alters Gag subcellular distribution, relocates sites of assembly, and reduces net virus particle production. These observations support a model for native HIV-1 assembly wherein HIV-1 gag-pol mRNA localization helps to confine interactions between Gag, viral RNAs, and host determinants in order to ensure virion production at the right place and right time. Direct perturbation of HIV-1 mRNA subcellular localization may represent a novel antiviral strategy.


Assuntos
Membrana Celular/química , Citoplasma/química , HIV-1/fisiologia , RNA Viral/análise , Vírion/metabolismo , Montagem de Vírus , Produtos do Gene gag do Vírus da Imunodeficiência Humana/metabolismo , Linhagem Celular , Humanos , RNA Mensageiro/análise
14.
J Mol Recognit ; 29(5): 199-209, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26620599

RESUMO

The binding of the HIV-1 Rev protein as an oligomer to a viral RNA element, the Rev-response element (RRE), mediates nuclear export of genomic RNA. Assembly of the Rev-RRE ribonucleoprotein (RNP) complex is nucleated by the binding of the first Rev molecule to stem IIB of the RRE. This is followed by stepwise addition of a total of ~six Rev molecules along the RRE through a combination of RNA-protein and protein-protein interactions. RRE stem II, which forms a three-way junction consisting of stems IIA, IIB and IIC, has been shown to bind to two Rev molecules in a cooperative manner, with the second Rev molecule binding to the junction region of stem II. The results of base substitutions at the stem II junction, and characterization of stem II junction variants selected from a randomized library showed that an "open" flexible structure is preferred for binding of the second Rev molecule, and that binding of the second Rev molecule to the junction region is not sequence-specific. Alanine substitutions of a number of Rev amino acid residues implicated to be important for Rev folding in previous structural studies were found to result in a dramatic decrease in the binding of the second Rev molecule. These results support the model that proper folding of Rev is critical in ensuring that the flexible RRE is able to correctly position Rev molecules for specific RNP assembly, and suggests that targeting Rev folding may be effective in the inhibition of Rev function.


Assuntos
HIV-1/genética , RNA Viral/metabolismo , Produtos do Gene rev do Vírus da Imunodeficiência Humana/química , Produtos do Gene rev do Vírus da Imunodeficiência Humana/metabolismo , Substituição de Aminoácidos , HIV-1/metabolismo , Modelos Moleculares , Conformação de Ácido Nucleico , Dobramento de Proteína , Multimerização Proteica , RNA Viral/química , Elementos de Resposta , Ribonucleoproteínas/metabolismo , Produtos do Gene rev do Vírus da Imunodeficiência Humana/genética
15.
Bioorg Med Chem ; 24(17): 3947-3952, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27091070

RESUMO

A branched peptide containing multiple boronic acids was found to bind RRE IIB selectively and inhibit HIV-1 p24 capsid production in a dose-dependent manner. Structure-activity relationship studies revealed that branching in the peptide is crucial for the low micromolar binding towards RRE IIB, and the peptide demonstrates selectivity towards RRE IIB in the presence of tRNA. Footprinting studies suggest a binding site on the upper stem and internal loop regions of the RNA, which induces enzymatic cleavage of the internal loops of RRE IIB upon binding.


Assuntos
Fármacos Anti-HIV/química , Ácidos Borônicos/química , Peptídeos/química , RNA Viral/química , Fármacos Anti-HIV/farmacologia , Ácidos Borônicos/farmacologia , Proteína do Núcleo p24 do HIV/antagonistas & inibidores , HIV-1/efeitos dos fármacos , HIV-1/genética , Células HeLa , Humanos , Inibidores de Integrase/farmacologia , Lamivudina/farmacologia , Conformação de Ácido Nucleico , Biblioteca de Peptídeos , Peptídeos/farmacologia , Quinolonas/farmacologia , RNA Viral/genética , RNA Viral/metabolismo , Raltegravir Potássico/farmacologia , Elementos de Resposta , Relação Estrutura-Atividade , Replicação Viral/efeitos dos fármacos , Zidovudina/farmacologia
16.
RNA Biol ; 12(2): 123-35, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25668122

RESUMO

Several proteins and RNAs expressed by mammalian viruses have been reported to interfere with RNA interference (RNAi) activity. We investigated the ability of the HIV-1-encoded RNA elements Trans-Activation Response (TAR) and Rev-Response Element (RRE) to alter RNAi. MicroRNA let7-based assays showed that RRE is a potent suppressor of RNAi activity, while TAR displayed moderate RNAi suppression. We demonstrate that RRE binds to TAR-RNA Binding Protein (TRBP), an essential component of the RNA Induced Silencing Complex (RISC). The binding of TAR and RRE to TRBP displaces small interfering (si)RNAs from binding to TRBP. Several stem-deleted RRE mutants lost their ability to suppress RNAi activity, which correlated with a reduced ability to compete with siRNA-TRBP binding. A lentiviral vector expressing TAR and RRE restricted RNAi, but RNAi was restored when Rev or GagPol were coexpressed. Adenoviruses are restricted by RNAi and encode their own suppressors of RNAi, the Virus-Associated (VA) RNA elements. RRE enhanced the replication of wild-type and VA-deficient adenovirus. Our work describes RRE as a novel suppressor of RNAi that acts by competing with siRNAs rather than by disrupting the RISC. This function is masked in lentiviral vectors co-expressed with viral proteins and thus will not affect their use in gene therapy. The potent RNAi suppressive effects of RRE identified in this study could be used to enhance the expression of RNAi restricted viruses used in oncolysis such as adenoviruses.


Assuntos
Genes env , Repetição Terminal Longa de HIV , HIV-1/genética , Interferência de RNA , Proteínas de Ligação a RNA/genética , Adenoviridae/genética , Adenoviridae/metabolismo , Ligação Competitiva , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Células HEK293 , HIV-1/metabolismo , Células HeLa , Interações Hospedeiro-Patógeno , Humanos , Células Jurkat , Lentivirus/genética , Lentivirus/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Conformação de Ácido Nucleico , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , RNA Viral/genética , RNA Viral/metabolismo , Proteínas de Ligação a RNA/metabolismo , Complexo de Inativação Induzido por RNA/genética , Complexo de Inativação Induzido por RNA/metabolismo , Produtos do Gene gag do Vírus da Imunodeficiência Humana/genética , Produtos do Gene gag do Vírus da Imunodeficiência Humana/metabolismo , Produtos do Gene pol do Vírus da Imunodeficiência Humana/genética , Produtos do Gene pol do Vírus da Imunodeficiência Humana/metabolismo
17.
Bioorg Med Chem ; 23(9): 2139-47, 2015 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-25819332

RESUMO

Nucleobase modified neamines with a lysine as the linker (NbK-neamines) were synthesized and their binding toward hairpin RNAs derived from HIV-1 activator region were studied. NbK-neamines were bind those RNAs with micro molar level of binding affinities and compete with corresponding activator peptide for TAR RNA, but not for RRE RNA. GbK-neamine denotes the highest binding affinity with TAR RNA, three to five times higher than other three NbK-neamines. GbK-neamine could be a candidate of potential inhibitor for TAR-Tat.


Assuntos
Framicetina/química , Framicetina/farmacologia , Repetição Terminal Longa de HIV/efeitos dos fármacos , HIV-1/química , HIV-1/genética , Lisina/química , Produtos do Gene tat do Vírus da Imunodeficiência Humana/antagonistas & inibidores , Adenina/química , Citosina/química , Framicetina/síntese química , Guanina/química , Estrutura Molecular , Relação Estrutura-Atividade , Timina/química
18.
Biochim Biophys Acta ; 1828(9): 2204-14, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23747294

RESUMO

We report the first 4-component phase diagram for the lipid bilayer mixture, DSPC/DOPC/POPC/chol (distearoylphosphatidylcholine/dioleoylphosphatidylcholine/1-palmitoyl, 2-oleoylphosphatidylcholine/cholesterol). This phase diagram, which has macroscopic Ld+Lo phase domains, clearly shows that all phase boundaries determined for the 3-component mixture containing DOPC transition smoothly into the boundaries for the 3-component mixture containing POPC, which has nanoscopic phase domains of Ld+Lo. Our studies start from two published ternary phase diagrams, and show how these can be combined into a quaternary phase diagram by study of a few hundred samples of intermediate compositions.


Assuntos
Colesterol/química , Fosfatidilcolinas/química , Transferência Ressonante de Energia de Fluorescência , Transição de Fase
19.
Clin Immunol ; 150(1): 51-63, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24333533

RESUMO

Adoptive immunotherapy using genetically targeted T-cells has recently begun to achieve impressive clinical impact in selected tumor types. Furthermore, long-term follow-up studies indicate thus far that integrating viral vectors do not elicit clinically evident genotoxicity in T-cells, unlike hematopoietic stem cells. The optimism engendered by this clinical experience provides a platform for consideration of the extended use of this technology in other disease types. One area of particular interest entails the harnessing of regulatory T-cells (Tregs) in order to down-regulate unwanted immune responses. Increasing evidence supports the efficacy of this approach in pre-clinical models of autoimmune disease and allograft rejection. Nonetheless, questions remain about optimal host cell, transgene cargo, phenotypic stability of engineered cells in vivo and potential for toxicity. Here, we review the evidence that genetically engineered Tregs can effectively dampen pathogenic immune responses and critically evaluate the prospects for clinical development of this approach.


Assuntos
Imunoterapia Adotiva , Linfócitos T Reguladores/imunologia , Animais , Doenças Autoimunes/imunologia , Humanos , Medição de Risco
20.
Int J Biol Macromol ; 258(Pt 2): 128093, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37981272

RESUMO

Precancerous lesions of gastric carcinoma (PLGC) are the most important stage in the development of gastric cancer, accompanied by significant oxidative stress and inflammatory response. Rosa roxburghii extract (RRE) has unique advantages in anti-PLGC due to its multi-component, high antioxidant and anti-inflammatory activities. However, the astringency and instability of RRE in the digestive tract seriously hinder its clinical application. Herein, we report a chitosan-based food-grade Pickering emulsion (PE) for loading RRE to block unpleasant taste, improve stability, and promote the entry of RRE into gastric epithelial cells through the gastric adhesion of chitosan, thereby enhancing preventive and therapeutic effects against PLGC. This Pickering emulsion is constructed as a water-in-oil (W/O) emulsion stabilized by the food-grade nanoparticles composed of soybean protein isolate (SPI) and chitosan (CS) through electrostatic interaction (defined as RRE@PE). The experimental results showed that RRE@PE performed better efficacy against PLGC than RRE by scavenging or inhibiting reactive oxygen species generation and reducing inflammatory cytokines. This Pickering emulsion enhances the application potential of RRE and is expected to be used for the treatment of clinical patients with PLGC.


Assuntos
Carcinoma , Quitosana , Nanopartículas , Rosa , Neoplasias Gástricas , Humanos , Emulsões , Tamanho da Partícula
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA