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1.
Dement Geriatr Cogn Disord ; 51(1): 73-79, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35287126

RESUMO

INTRODUCTION: Person-centred care (PCC) is synonymous with best practice in the care of persons with dementia. Despite this, PCC is not routinely assessed, and there is no validated tool for in the acute care setting. We aimed to validate the Person-Centred Assessment Tool (P-CAT) in an acute setting. METHODS: P-CAT was administered independently to a total of 161 nurses (n = 16, from a specialized dementia unit with PCC training; n = 116, geriatric wards; n = 30, medical/surgical wards). The word "residents" was replaced with "patients" in P-CAT. We employed confirmatory factor analysis with principal component extraction to verify the previously reported three- and two-factor solutions. A one-way between-groups ANOVA was then used to investigate group differences in the P-CAT score (total scale and subscale). RESULTS: Factor analysis revealed a two-factor solution (explained variance 42.28%): (i) extent of personalizing care and (ii) amount of organizational and environmental support. Out of the 13 items, only 2 items did not load as expected. The internal consistency reliability of the scale was satisfactory (Cronbach's α = 0.77). Nurses' P-CAT scores were significantly different across ward settings [Welch's F(2,37.20) = 13.01, p < 0.001, ω2 = 0.09], with the highest among those PCC trained. Post hoc analyses revealed a significant difference in mean subscale scores between PCC-trained nurses and nurses from the other two ward settings. P-CAT scores were not significantly correlated with age, r(159) = 0.01, p = 0.861, or with nursing experience, r(159) = 0.04, p = 0.615. DISCUSSION/CONCLUSION: P-CAT possesses adequate validity and reliability as a quantitative assessment tool of PCC in the acute care setting.


Assuntos
Demência , Assistência Centrada no Paciente , Idoso , Demência/diagnóstico , Demência/terapia , Análise Fatorial , Humanos , Psicometria , Reprodutibilidade dos Testes , Inquéritos e Questionários
2.
Elife ; 102021 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-34870592

RESUMO

The Src tyrosine kinase controls cancer-critical protein glycosylation through Golgi to ER relocation of GALNTs enzymes. How Src induces this trafficking event is unknown. Golgi to ER transport depends on the GTP exchange factor (GEF) GBF1 and small GTPase Arf1. Here, we show that Src induces the formation of tubular transport carriers containing GALNTs. The kinase phosphorylates GBF1 on 10 tyrosine residues; two of them, Y876 and Y898, are located near the C-terminus of the Sec7 GEF domain. Their phosphorylation promotes GBF1 binding to the GTPase; molecular modeling suggests partial melting of the Sec7 domain and intramolecular rearrangement. GBF1 mutants defective for these rearrangements prevent binding, carrier formation, and GALNTs relocation, while phosphomimetic GBF1 mutants induce tubules. In sum, Src promotes GALNTs relocation by promoting GBF1 binding to Arf1. Based on residue conservation, similar regulation of GEF-Arf complexes by tyrosine phosphorylation could be a conserved and widespread mechanism.


Assuntos
Fatores de Troca do Nucleotídeo Guanina/genética , Quinases da Família src/genética , Retículo Endoplasmático/metabolismo , Complexo de Golgi/metabolismo , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Humanos , Fosforilação , Transporte Proteico , Quinases da Família src/metabolismo
3.
Nat Commun ; 12(1): 5315, 2021 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-34493720

RESUMO

Human PAK4 is an ubiquitously expressed p21-activated kinase which acts downstream of Cdc42. Since PAK4 is enriched in cell-cell junctions, we probed the local protein environment around the kinase with a view to understanding its location and substrates. We report that U2OS cells expressing PAK4-BirA-GFP identify a subset of 27 PAK4-proximal proteins that are primarily cell-cell junction components. Afadin/AF6 showed the highest relative biotin labelling and links to the nectin family of homophilic junctional proteins. Reciprocally >50% of the PAK4-proximal proteins were identified by Afadin BioID. Co-precipitation experiments failed to identify junctional proteins, emphasizing the advantage of the BioID method. Mechanistically PAK4 depended on Afadin for its junctional localization, which is similar to the situation in Drosophila. A highly ranked PAK4-proximal protein LZTS2 was immuno-localized with Afadin at cell-cell junctions. Though PAK4 and Cdc42 are junctional, BioID analysis did not yield conventional cadherins, indicating their spatial segregation. To identify cellular PAK4 substrates we then assessed rapid changes (12') in phospho-proteome after treatment with two PAK inhibitors. Among the PAK4-proximal junctional proteins seventeen PAK4 sites were identified. We anticipate mammalian group II PAKs are selective for the Afadin/nectin sub-compartment, with a demonstrably distinct localization from tight and cadherin junctions.


Assuntos
Junções Intercelulares/metabolismo , Proteínas dos Microfilamentos/genética , Nectinas/genética , Proteômica/métodos , Proteína cdc42 de Ligação ao GTP/genética , Quinases Ativadas por p21/genética , Biotina/química , Carbono-Nitrogênio Ligases/genética , Carbono-Nitrogênio Ligases/metabolismo , Linhagem Celular Tumoral , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Junções Intercelulares/genética , Junções Intercelulares/ultraestrutura , Marcação por Isótopo , Espectrometria de Massas , Proteínas dos Microfilamentos/metabolismo , Nectinas/metabolismo , Osteoblastos/metabolismo , Osteoblastos/ultraestrutura , Ligação Proteica , Mapeamento de Interação de Proteínas , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transdução de Sinais , Proteína cdc42 de Ligação ao GTP/metabolismo , Quinases Ativadas por p21/metabolismo
4.
Dement Geriatr Cogn Disord ; 50(3): 250-257, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34348291

RESUMO

BACKGROUND: Person-centred care (PCC) is synonymous with best practice in the care of persons with dementia. However, the research focus has been in long-term care settings with less attention in acute hospitals. We aimed to study the perspectives and experiences of nurses implementing PCC in an acute hospital dementia unit (Care for Acute Mentally Infirm Elders [CAMIE]). METHOD: This was an exploratory qualitative study involving individual, face-to-face, semi-structured in-depth interviews. A purposive sample of 10 nurses participated in the interview. We employed an inductive thematic analysis approach to analyse the qualitative data. RESULTS: The findings highlighted the positive experiences, for example, meaningful connection with patients and the challenges, for example, managing challenging behaviour in providing PCC. The initial challenges were due to a lack of prior knowledge and experience. Through formal and informal learning, the nurses built confidence and competence, and also provided support to one other. They emphasized the importance of teamwork and camaraderie in the CAMIE team but raised concerns about the negative perceptions of non-CAMIE nurses on the value of their work. CONCLUSION: Despite the challenges, adequate knowledge and robust organizational level support are the key support for nurses to embrace PCC as their care ethos in the acute care setting.


Assuntos
Demência , Idoso , Demência/terapia , Hospitais , Humanos , Pesquisa Qualitativa
5.
PLoS One ; 14(3): e0214118, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30889231

RESUMO

The enzymes GALNTs add GalNAc sugar to Ser and Thr residues, forming the Tn glycan. GALNTs are activated by trafficking from Golgi to ER, a process driven by the Src kinase and negatively regulated by ERK8. This GALNTs activation (aka GALA) pathway induces high Tn levels and is a key driver of liver tumor growth. Recently, Tabak and colleagues have contested our previous data that EGF stimulation can induce GALNTs relocation. Here, we show that relocation induced by EGF is actually detectable in the very images acquired by Tabak et al. Furthermore, we show that over-expression of EGFR strongly enhances EGF-induced relocation and that EGFR appears required to drive relocation induced by ERK8 depletion. Direct co-localisation of GALNT with the ER marker Calnexin is observed after EGF stimulation. We furthermore propose that quantification of O-glycosylation of the ER resident protein PDIA4 provides a mean to quantify GALA independently of imaging. In sum, we demonstrate that the claimed non-reproducibility was due to experimental imaging conditions, that EGFR is indeed a driver of GALA and propose additional markers to facilitate the study of this pathway.


Assuntos
Retículo Endoplasmático/enzimologia , N-Acetilgalactosaminiltransferases/metabolismo , Retículo Endoplasmático/genética , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Glicosilação , Células HEK293 , Células HeLa , Humanos , N-Acetilgalactosaminiltransferases/genética , Isomerases de Dissulfetos de Proteínas/genética , Isomerases de Dissulfetos de Proteínas/metabolismo
6.
Alzheimers Dement (N Y) ; 4: 19-27, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29955648

RESUMO

INTRODUCTION: Patients with dementia (PWDs) are often subjected to enforced dependency and experience functional decline and emotional distress during hospital stay. Person-centered care (PCC) with specialized psychosocial interventions, minimally obtrusive medical care, and physical restraints-free practice holds potential to improve patient outcomes. We evaluate the effectiveness of an acute hospital dementia unit (Care for Acute Mentally Infirm Elders [CAMIE]) that adopts a PCC protocol. METHODS: Prospective naturalistic cohort study whereby PWDs in the CAMIE unit (n = 170) were compared with a control group in usual care wards (n = 60) over 6 months. Assessments included patient demographics, dementia type and stage, comorbidities (Charlson's Comorbidity Index), acute illness severity, Well-Being, Ill-Being, functional status (Modified Barthel Index), agitation levels (Pittsburgh Agitation Scale), and quality of life (EuroQoL), assessed on admission and discharge. Multivariate analysis of covariance examined the effect of CAMIE versus usual care on pre-post outcomes. RESULTS: CAMIE patients showed statistically significant greater gains in Modified Barthel Index function and Well-Being, decreased Ill-Being and agitation, and greater improvement in EuroQoL index score (effect size: Δ = 0.18) after adjusting for baseline differences that translated to a quality-adjusted life years gain of 0.045, assuming stability over 3 months. Estimating added cost of CAMIE stay over usual care at SGD 1500 (USD 1040) for average length of stay of 15 days per patient, the incremental cost-effectiveness ratio fell within the threshold for cost-effectiveness at USD 23,111. DISCUSSION: PCC for PWDs in acute hospitals not only improves clinical outcomes for patients but is also cost-effective. The results support the adoption of PCC on a wider scale for better care of PWDs.

7.
Sci Signal ; 9(432): rs4, 2016 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-27303058

RESUMO

Focal adhesions are protein complexes that link metazoan cells to the extracellular matrix through the integrin family of transmembrane proteins. Integrins recruit many proteins to these complexes, referred to as the "adhesome." We used proximity-dependent biotinylation (BioID) in U2OS osteosarcoma cells to label proteins within 15 to 25 nm of paxillin, a cytoplasmic focal adhesion protein, and kindlin-2, which directly binds ß integrins. Using mass spectrometry analysis of the biotinylated proteins, we identified 27 known adhesome proteins and 8 previously unknown components close to paxillin. However, only seven of these proteins interacted directly with paxillin, one of which was the adaptor protein Kank2. The proteins in proximity to ß integrin included 15 of the adhesion proteins identified in the paxillin BioID data set. BioID also correctly established kindlin-2 as a cell-cell junction protein. By focusing on this smaller data set, new partners for kindlin-2 were found, namely, the endocytosis-promoting proteins liprin ß1 and EFR3A, but, contrary to previous reports, not the filamin-binding protein migfilin. A model adhesome based on both data sets suggests that focal adhesions contain fewer components than previously suspected and that paxillin lies away from the plasma membrane. These data not only illustrate the power of using BioID and stable isotope-labeled mass spectrometry to define macromolecular complexes but also enable the correct identification of therapeutic targets within the adhesome.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Proteínas de Transporte , Moléculas de Adesão Celular , Proteínas do Citoesqueleto , Adesões Focais , Proteínas Supressoras de Tumor , Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Proteínas Reguladoras de Apoptose , Biotinilação , Células COS , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Moléculas de Adesão Celular/química , Moléculas de Adesão Celular/metabolismo , Linhagem Celular Tumoral , Chlorocebus aethiops , Proteínas do Citoesqueleto/química , Proteínas do Citoesqueleto/metabolismo , Adesões Focais/química , Adesões Focais/metabolismo , Humanos , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Camundongos , Proteínas de Neoplasias/química , Proteínas de Neoplasias/metabolismo , Proteínas Supressoras de Tumor/química , Proteínas Supressoras de Tumor/metabolismo
8.
J Virol ; 89(21): 11116-28, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26311884

RESUMO

UNLABELLED: Coronaviruses are RNA viruses with a large zoonotic reservoir and propensity for host switching, representing a real threat for public health, as evidenced by severe acute respiratory syndrome (SARS) and the emerging Middle East respiratory syndrome (MERS). Cellular factors required for their replication are poorly understood. Using genome-wide small interfering RNA (siRNA) screening, we identified 83 novel genes supporting infectious bronchitis virus (IBV) replication in human cells. Thirty of these hits can be placed in a network of interactions with viral proteins and are involved in RNA splicing, membrane trafficking, and ubiquitin conjugation. In addition, our screen reveals an unexpected role for valosin-containing protein (VCP/p97) in early steps of infection. Loss of VCP inhibits a previously uncharacterized degradation of the nucleocapsid N protein. This inhibition derives from virus accumulation in early endosomes, suggesting a role for VCP in the maturation of virus-loaded endosomes. The several host factors identified in this study may provide avenues for targeted therapeutics. IMPORTANCE: Coronaviruses are RNA viruses representing a real threat for public health, as evidenced by SARS and the emerging MERS. However, cellular factors required for their replication are poorly understood. Using genome-wide siRNA screening, we identified novel genes supporting infectious bronchitis virus (IBV) replication in human cells. The several host factors identified in this study may provide directions for future research on targeted therapeutics.


Assuntos
Adenosina Trifosfatases/metabolismo , Proteínas de Ciclo Celular/metabolismo , Infecções por Coronavirus/transmissão , Endossomos/virologia , Vírus da Bronquite Infecciosa/fisiologia , Liberação de Vírus/fisiologia , Adenosina Trifosfatases/genética , Animais , Western Blotting , Proteínas de Ciclo Celular/genética , Linhagem Celular , Chlorocebus aethiops , Imunofluorescência , Estudo de Associação Genômica Ampla , Humanos , Anotação de Sequência Molecular , RNA Interferente Pequeno/genética , Proteína com Valosina , Células Vero
9.
Virology ; 433(2): 421-30, 2012 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-22995191

RESUMO

In previous studies, the Beaudette strain of coronavirus infectious bronchitis virus (IBV) was adapted from chicken embryo to Vero, a monkey kidney cell line, by serial propagation for 65 passages. To characterize the susceptibility of other human and animal cells to IBV, 15 human and animal cell lines were infected with the Vero-adapted IBV and productive infection was observed in four human cell lines: H1299, HepG2, Hep3B and Huh7. In other cell lines, the virus cannot be propagated beyond passage 5. Interestingly, cellular furin abundance in five human cell lines was shown to be strongly correlated with productive IBV infection. Cleavage of IBV spike protein by furin may contribute to the productive IBV infection in these cells. The findings that IBV could productively infect multiple human and animal cells of diverse tissue and organ origins would provide a useful system for studying the pathogenesis of coronavirus.


Assuntos
Infecções por Coronavirus/etiologia , Furina/metabolismo , Vírus da Bronquite Infecciosa , Animais , Sequência de Bases , Sítios de Ligação , Linhagem Celular , Chlorocebus aethiops , Infecções por Coronavirus/metabolismo , Infecções por Coronavirus/virologia , Proteínas M de Coronavírus , Proteínas do Nucleocapsídeo de Coronavírus , Furina/antagonistas & inibidores , Furina/genética , Técnicas de Silenciamento de Genes , Células Hep G2 , Interações Hospedeiro-Patógeno , Humanos , Vírus da Bronquite Infecciosa/patogenicidade , Vírus da Bronquite Infecciosa/fisiologia , Glicoproteínas de Membrana/metabolismo , Proteínas do Nucleocapsídeo/metabolismo , RNA Interferente Pequeno/genética , Glicoproteína da Espícula de Coronavírus , Células Vero , Proteínas do Envelope Viral/metabolismo , Proteínas da Matriz Viral/metabolismo , Cultura de Vírus
10.
J Virol ; 84(17): 8571-83, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20573827

RESUMO

The involvement of host proteins in the replication and transcription of viral RNA is a poorly understood area for many RNA viruses. For coronaviruses, it was long speculated that replication of the giant RNA genome and transcription of multiple subgenomic mRNA species by a unique discontinuous transcription mechanism may require host cofactors. To search for such cellular proteins, yeast two-hybrid screening was carried out by using the nonstructural protein 14 (nsp14) from the coronavirus infectious bronchitis virus (IBV) as a bait protein, leading to the identification of DDX1, a cellular RNA helicase in the DExD/H helicase family, as a potential interacting partner. This interaction was subsequently confirmed by coimmunoprecipitation assays with cells coexpressing the two proteins and with IBV-infected cells. Furthermore, the endogenous DDX1 protein was found to be relocated from the nucleus to the cytoplasm in IBV-infected cells. In addition to its interaction with IBV nsp14, DDX1 could also interact with the nsp14 protein from severe acute respiratory syndrome coronavirus (SARS-CoV), suggesting that interaction with DDX1 may be a general feature of coronavirus nsp14. The interacting domains were mapped to the C-terminal region of DDX1 containing motifs V and VI and to the N-terminal portion of nsp14. Manipulation of DDX1 expression, either by small interfering RNA-induced knockdown or by overexpression of a mutant DDX1 protein, confirmed that this interaction may enhance IBV replication. This study reveals that DDX1 contributes to efficient coronavirus replication in cell culture.


Assuntos
Infecções por Coronavirus/metabolismo , RNA Helicases DEAD-box/metabolismo , Vírus da Bronquite Infecciosa/fisiologia , Proteínas não Estruturais Virais/metabolismo , Replicação Viral , Animais , Núcleo Celular/metabolismo , Chlorocebus aethiops , Infecções por Coronavirus/genética , Infecções por Coronavirus/virologia , Citoplasma/metabolismo , RNA Helicases DEAD-box/genética , Células HeLa , Humanos , Vírus da Bronquite Infecciosa/genética , Ligação Proteica , Transporte Proteico , Técnicas do Sistema de Duplo-Híbrido , Células Vero , Proteínas não Estruturais Virais/genética
11.
J Virol ; 84(14): 7325-36, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20444893

RESUMO

Coronavirus (CoV) 3C-like proteinase (3CLpro), located in nonstructural protein 5 (nsp5), processes the replicase polyproteins 1a and 1ab (pp1a and pp1ab) at 11 specific sites to produce 12 mature nonstructural proteins (nsp5 to nsp16). Structural and biochemical studies suggest that a conserved Gln residue at the P1 position is absolutely required for efficient cleavage. Here, we investigate the effects of amino acid substitution at the P1 position of 3CLpro cleavage sites of infectious bronchitis virus (IBV) on the cleavage efficiency and viral replication by in vitro cleavage assays and reverse genetic approaches. Our results demonstrated that a P1-Asn substitution at the nsp4-5/Q2779, nsp5-6/Q3086, nsp7-8/Q3462, nsp8-9/Q3672, and nsp9-10/Q3783 sites, a P1-Glu substitution at the nsp8-9/Q3672 site, and a P1-His substitution at the nsp15-16/Q6327 site were tolerated and allowed recovery of infectious mutant viruses, albeit with variable degrees of growth defects. In contrast, a P1-Asn substitution at the nsp6-7/Q3379, nsp12-13/Q4868, nsp13-14/Q5468, and nsp14-15/Q5989 sites, as well as a P1-Pro substitution at the nsp15-16/Q6327 site, abolished 3CLpro-mediated cleavage at the corresponding position and blocked the recovery of infectious viruses. Analysis of the effects of these lethal mutations on RNA synthesis suggested that processing intermediates, such as the nsp6-7, nsp12-13, nsp13-14, nsp14-15, and nsp15-16 precursors, may function in negative-stranded genomic RNA replication, whereas mature proteins may be required for subgenomic RNA (sgRNA) transcription. More interestingly, a mutant 3CLpro with either a P166S or P166L mutation was selected when an IBV infectious cDNA clone carrying the Q6327N mutation at the nsp15-16 site was introduced into cells. Either of the two mutations was proved to enhance significantly the 3CLpro-mediated cleavage efficiency at the nsp15-16 site with a P1-Asn substitution and compensate for the detrimental effects on recovery of infectious virus.


Assuntos
Cisteína Endopeptidases , Vírus da Bronquite Infecciosa , Proteínas Virais , Proteases Virais 3C , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Cisteína Endopeptidases/genética , Cisteína Endopeptidases/metabolismo , Humanos , Vírus da Bronquite Infecciosa/enzimologia , Vírus da Bronquite Infecciosa/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Especificidade por Substrato/genética , Proteínas Virais/genética , Proteínas Virais/metabolismo
12.
PLoS One ; 4(7): e6130, 2009 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-19572016

RESUMO

Coronavirus host and cell specificities are determined by specific interactions between the viral spike (S) protein and host cell receptor(s). Avian coronavirus infectious bronchitis (IBV) has been adapted to embryonated chicken eggs, primary chicken kidney (CK) cells, monkey kidney cell line Vero, and other human and animal cells. Here we report that acquisition of the cell-cell fusion activity by amino acid mutations in the S protein determines the infectivity of IBV in cultured cells. Expression of S protein derived from Vero- and CK-adapted strains showed efficient induction of membrane fusion. However, expression of S protein cloned from the third passage of IBV in chicken embryo (EP3) did not show apparent syncytia formation. By construction of chimeric S constructs and site-directed mutagenesis, a point mutation (L857-F) at amino acid position 857 in the heptad repeat 1 region of S protein was shown to be responsible for its acquisition of the cell-cell fusion activity. Furthermore, a G405-D point mutation in the S1 domain, which was acquired during further propagation of Vero-adapted IBV in Vero cells, could enhance the cell-cell fusion activity of the protein. Re-introduction of L857 back to the S gene of Vero-adapted IBV allowed recovery of variants that contain the introduced L857. However, compensatory mutations in S1 and some distant regions of S2 were required for restoration of the cell-cell fusion activity of S protein carrying L857 and for the infectivity of the recovered variants in cultured cells. This study demonstrates that acquisition of the cell-cell fusion activity in S protein determines the selection and/or adaptation of a coronavirus from chicken embryo to cultured cells of human and animal origins.


Assuntos
Substituição de Aminoácidos , Fusão Celular , Coronavirus/patogenicidade , Glicoproteínas de Membrana/fisiologia , Proteínas do Envelope Viral/fisiologia , Sequência de Aminoácidos , Animais , Western Blotting , Células Cultivadas , Eletroporação , Citometria de Fluxo , Imunofluorescência , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Homologia de Sequência de Aminoácidos , Glicoproteína da Espícula de Coronavírus , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/genética
13.
J Virol Methods ; 160(1-2): 48-56, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19409420

RESUMO

Manipulation of the coronavirus genome to accommodate and express foreign genes is an attractive approach for gene delivery and vaccine development. By using an infectious cloning system developed recently for the avian coronavirus infectious bronchitis virus (IBV), the enhanced green fluorescent protein (EGFP) gene, the firefly luciferase gene and several host and viral genes (eIF3f, SARS ORF6, Dengue virus 1 core protein gene) were inserted into various positions of the IBV genome, and the effects on gene expression, virus recovery, and stability in cell culture were studied. Selected viruses were also inoculated into chicken embryos for studies of foreign gene expression at different tissue level. The results demonstrated the stability of recombinant viruses depends on the intrinsic properties of the foreign gene itself as well as the position at which the foreign genes were inserted. For unstable viruses, the loss of expression of the inserted genes was found to result from a large deletion of the inserted gene and even IBV backbone sequences. This represents a promising system for development of coronavirus-based gene delivery vectors and vaccines against coronavirus and other viral infections in chicken.


Assuntos
Terapia Genética , Vetores Genéticos , Vírus da Bronquite Infecciosa/genética , Vacinas Virais/genética , Animais , Embrião de Galinha , Galinhas , Vírus da Dengue/genética , Genes Reporter , Instabilidade Genômica , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Luciferases de Vaga-Lume/genética , Luciferases de Vaga-Lume/metabolismo , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/genética , Deleção de Sequência , Proteínas Virais/genética , Vacinas Virais/imunologia
14.
Virology ; 379(2): 175-80, 2008 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-18678384

RESUMO

Coronavirus 3C-like proteinase (3CLpro) plays important roles in viral life cycle through extensive processing of the polyproteins 1a and 1ab into 12 mature, non-structural proteins (nsp5-nsp16). Structural and biochemical studies have revealed that all confirmed 3CLpro cleavage sites have a conserved Gln residue at the P1 position, which is thought to be absolutely required for efficient cleavage. Recent studies on murine hepatitis virus (MHV) showed that processing of the 1a polyprotein at the position between nsp10-nsp11 is essential for viral replication. In this report, we investigated the requirement of processing at the equivalent position for replication of avian coronavirus infectious bronchitis virus (IBV), using an infectious cloning system. The results showed that mutation of the P1 Gln to Pro or deletion of the Gln residue in the nsp10-nsp11/12 site completely abolished the 3CLpro-mediated processing, but allowed production of infectious recombinant viruses with variable degrees of growth defect, suggesting that cleavage at the nsp10-nsp11/12 site of IBV is dispensable for viral replication in cultured cells. This study would pave a way for potential vaccine development by generation of attenuated IBV from field isolates through manipulation of the nsp10-nsp11/12 cleavage site. Similar approaches would be also applicable to other human and animal coronaviruses.


Assuntos
Vírus da Bronquite Infecciosa/metabolismo , Proteínas não Estruturais Virais/metabolismo , Proteínas Virais/metabolismo , Substituição de Aminoácidos , Animais , Domínio Catalítico/genética , Chlorocebus aethiops , Proteases 3C de Coronavírus , Cisteína Endopeptidases/química , Cisteína Endopeptidases/genética , Cisteína Endopeptidases/metabolismo , Humanos , Vírus da Bronquite Infecciosa/genética , Vírus da Bronquite Infecciosa/fisiologia , Mutagênese Sítio-Dirigida , Processamento de Proteína Pós-Traducional , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Deleção de Sequência , Células Vero , Replicação Viral
15.
FEBS J ; 274(16): 4211-22, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17645546

RESUMO

The most striking difference between the subgenomic mRNA8 of severe acute respiratory syndrome coronavirus isolated from human and some animal species is the deletion of 29 nucleotides, resulting in splitting of a single ORF (ORF8) into two ORFs (ORF8a and ORF8b). ORF8a and ORF8b are predicted to encode two small proteins, 8a and 8b, and ORF8 a single protein, 8ab (a fusion form of 8a and 8b). To understand the functions of these proteins, we cloned cDNA fragments covering these ORFs into expression plasmids, and expressed the constructs in both in vitro and in vivo systems. Expression of a construct containing ORF8a and ORF8b generated only a single protein, 8a; no 8b protein expression was obtained. Expression of a construct containing ORF8 generated the 8ab fusion protein. Site-directed mutagenesis and enzymatic treatment revealed that protein 8ab is modified by N-linked glycosylation on the N81 residue and by ubiquitination. In the absence of the 8a region, protein 8b undergoes rapid degradation by proteasomes, and addition of proteasome inhibitors inhibits the degradation of protein 8b as well as the protein 8b-induced rapid degradation of the severe acute respiratory syndrome coronavirus E protein. Glycosylation could also stabilize protein 8ab. More interestingly, the two proteins could bind to monoubiquitin and polyubiquitin, suggesting the potential involvement of these proteins in the pathogenesis of severe acute respiratory syndrome coronavirus.


Assuntos
Genoma Viral , RNA Mensageiro/genética , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/metabolismo , Proteínas Virais/metabolismo , Animais , Northern Blotting , Western Blotting , Células COS , Chlorocebus aethiops , Clonagem Molecular , Regulação Viral da Expressão Gênica/efeitos dos fármacos , Glicosilação/efeitos dos fármacos , Humanos , Inibidores de Proteases/farmacologia , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/genética , Síndrome Respiratória Aguda Grave/virologia , Ubiquitina/metabolismo , Células Vero , Proteínas Virais/genética
16.
Virology ; 358(1): 136-47, 2007 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-16979681

RESUMO

Genetic manipulation of the RNA genomes by reverse genetics is a powerful tool to study the molecular biology and pathogenesis of RNA viruses. During construction of an infectious clone from a Vero cell-adapted coronavirus infectious bronchitis virus (IBV), we found that a G-C point mutation at nucleotide position 15526, causing Arg-to-Pro mutation at amino acid position 132 of the helicase protein, is lethal to the infectivity of IBV on Vero cells. When the in vitro-synthesized full-length transcripts containing this mutation were introduced into Vero cells, no infectious virus was rescued. Upon correction of the mutation, infectious virus was recovered. Further characterization of the in vitro-synthesized full-length transcripts containing the G15526C mutation demonstrated that this mutation may block the transcription of subgenomic RNAs. Substitution mutation of the Arg132 residue to a positively charged amino acid Lys affected neither the infectivity of the in vitro-synthesized transcripts nor the growth properties of the rescued virus. However, mutation of the Arg132 residue to Leu, a conserved residue in other coronaviruses at the same position, reduced the recovery rate of the in vitro-synthesized transcripts. The recovered mutant virus showed much smaller-sized plaques. On the contrary, a G-C and a G-A point mutations at nucleotide positions 4330 and 9230, respectively, causing Glu-Gln and Gly-Glu mutations in or near the catalytic centers of the papain-like (Nsp3) and 3C-like (Nsp5) proteinases, did not show detectable detrimental effect on the rescue of infectious viruses and the infectivity of the rescued viruses.


Assuntos
Vírus da Bronquite Infecciosa/crescimento & desenvolvimento , Vírus da Bronquite Infecciosa/genética , Mutação Puntual , RNA Helicases/genética , Proteínas Virais/genética , Replicação Viral/genética , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Animais , Chlorocebus aethiops , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Peptídeo Hidrolases/genética , Peptídeo Hidrolases/fisiologia , RNA Helicases/fisiologia , RNA Viral/metabolismo , Homologia de Sequência de Aminoácidos , Transcrição Gênica , Células Vero , Ensaio de Placa Viral , Proteínas Virais/fisiologia
17.
Biochem Biophys Res Commun ; 336(2): 417-23, 2005 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-16137658

RESUMO

An interesting question posed by the current evidence that severe acute respiratory syndrome coronavirus may be originated from an animal coronavirus is how such an animal coronavirus breaks the host species barrier and becomes zoonotic. In this report, we study the chronological order of genotypic changes in the spike protein of avian coronavirus infectious bronchitis virus (IBV) during its adaptation to a primate cell line. Adaptation of the Beaudette strain of IBV from chicken embryo to Vero cells showed the accumulation of 49 amino acid mutations. Among them, 26 (53.06%) substitutions were located in the S protein. Sequencing analysis and comparison of the S gene demonstrated that the majority of the mutations were accumulated and fixed at passage 7 on Vero cells and minor variants were isolated in several passages. Evidence present suggests that the dominant Vero cell-adapted IBV strain may be derived from the chicken embryo passages by selection of and potential recombination between the minor variants. This may explain why adaptation is a rapid process and the dominant strain, once adapted to a new host cell, becomes relatively stable.


Assuntos
Adaptação Fisiológica/genética , Galinhas/virologia , Chlorocebus aethiops/virologia , Vírus da Bronquite Infecciosa/genética , Glicoproteínas de Membrana/genética , Recombinação Genética/genética , Seleção Genética , Proteínas do Envelope Viral/genética , Sequência de Aminoácidos , Animais , Transferência Genética Horizontal/genética , Variação Genética/genética , Glicoproteínas de Membrana/química , Dados de Sequência Molecular , Primatas/virologia , Glicoproteína da Espícula de Coronavírus , Células Vero , Proteínas do Envelope Viral/química
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