RESUMO
The COVID-19 pandemic has had high mortality rates in the elderly and frail worldwide, particularly in care homes. This is driven by the difficulty of isolating care homes from the wider community, the large population sizes within care facilities (relative to typical households), and the age/frailty of the residents. To quantify the mortality risk posed by disease, the case fatality risk (CFR) is an important tool. This quantifies the proportion of cases that result in death. Throughout the pandemic, CFR amongst care home residents in England has been monitored closely. To estimate CFR, we apply both novel and existing methods to data on deaths in care homes, collected by Public Health England and the Care Quality Commission. We compare these different methods, evaluating their relative strengths and weaknesses. Using these methods, we estimate temporal trends in the instantaneous CFR (at both daily and weekly resolutions) and the overall CFR across the whole of England, and dis-aggregated at regional level. We also investigate how the CFR varies based on age and on the type of care required, dis-aggregating by whether care homes include nursing staff and by age of residents. This work has contributed to the summary of measures used for monitoring the UK epidemic.
Assuntos
COVID-19 , Humanos , Idoso , COVID-19/epidemiologia , Pandemias , Casas de Saúde , Densidade Demográfica , Inglaterra/epidemiologiaRESUMO
Disease development in human T-cell leukemia virus type 1 (HTLV-1)-infected individuals is positively correlated with the level of integrated viral DNA in T cells. HTLV-1 replication is positively regulated by Tax and Rex and negatively regulated by the p30 and HBZ proteins. In the present study, we demonstrate that HTLV-1 encodes another negative regulator of virus expression, the p13 protein. Expressed separately, p13 localizes to the mitochondria, whereas in the presence of Tax, part of it is ubiquitinated, stabilized, and rerouted to the nuclear speckles. The p13 protein directly binds Tax, decreases Tax binding to the CBP/p300 transcriptional coactivator, and, by reducing Tax transcriptional activity, suppresses viral expression. Because Tax stabilizes its own repressor, these findings suggest that HTLV-1 has evolved a complex mechanism to control its own replication. Further, these results highlight the importance of studying the function of the HTLV-1 viral proteins, not only in isolation, but also in the context of full viral replication.
Assuntos
Núcleo Celular/metabolismo , Produtos do Gene tax/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Proteínas dos Retroviridae/metabolismo , Replicação Viral/fisiologia , Western Blotting , Linhagem Celular , Regulação Viral da Expressão Gênica , Produtos do Gene tax/genética , Células HEK293 , Células HeLa , Vírus Linfotrópico T Tipo 1 Humano/genética , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , Humanos , Imunoprecipitação , Microscopia Confocal , Membranas Mitocondriais/metabolismo , Ligação Proteica , Proteínas dos Retroviridae/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Replicação Viral/genética , Fatores de Transcrição de p300-CBP/metabolismoRESUMO
Adult T-cell leukemia/lymphoma (ATLL) is an aggressive lymphoproliferative disease of very poor clinical prognosis associated with infection by the human T-cell leukemia virus type I (HTLV-I). Treatment of patients with ATLL using conventional chemotherapy has limited benefit because HTLV-I cells are refractory to most apoptosis-inducing agents. In this study, we report that Celecoxib induces cell death via the intrinsic mitochondrial pathway in HTLV-I transformed leukemia cells. Treatment with Celecoxib was associated with activation of Bax, decreased expression of Mcl-1, loss of the mitochondrial membrane potential and caspase-9-dependent apoptosis. These effects were independent from Bcl-2 and Bcl-xL. We also found that Celecoxib inhibited the Akt/GSK3 beta survival pathway in HTLV-I cells.
Assuntos
Apoptose/efeitos dos fármacos , Inibidores de Ciclo-Oxigenase/farmacologia , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Leucemia-Linfoma de Células T do Adulto/patologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Pirazóis/farmacologia , Sulfonamidas/farmacologia , Proteína X Associada a bcl-2/metabolismo , Celecoxib , Linhagem Celular Transformada , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Leucemia-Linfoma de Células T do Adulto/metabolismo , Mitocôndrias/metabolismo , Proteína de Sequência 1 de Leucemia de Células Mieloides , Proteínas de Neoplasias/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteína bcl-X/metabolismoRESUMO
Human T-cell lymphotrophic virus type I Rex and p30 are both RNA binding regulatory proteins. Rex is a protein that interacts with a responsive element and stimulates nuclear export of incompletely spliced viral RNAs thereby increasing production of virus particles. In contrast, p30 is involved in the nuclear retention of the tax/rex mRNA leading to inhibition of virus expression and possible establishment of viral latency. How these two proteins, with apparent opposite functions, integrate in the viral replication cycle is unknown. Here, we demonstrate that Rex and p30 form ribonucleoprotein ternary complexes onto specific viral mRNA. Our results explain the selective nuclear retention of tax/rex but not other viral mRNAs by p30. Whereas p30 suppresses Rex expression, it did not affect Rex-mediated nuclear export of RNA containing the Rex response element. In contrast, Rex was able to counteract p30-mediated suppression of viral expression and restore cytoplasmic tax/rex mRNA and Tax protein expression. Together, our data demonstrate a complex regulatory mechanism of antagonizing post-transcriptional regulators evolved by human T-cell lymphotrophic virus type I to allow a vigilant control of viral gene expression.
Assuntos
Regulação Viral da Expressão Gênica , Produtos do Gene rex/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/genética , RNA Viral/metabolismo , Proteínas dos Retroviridae/metabolismo , Latência Viral , Replicação Viral , Animais , Células COS , Linhagem Celular , Chlorocebus aethiops , Produtos do Gene rex/genética , Genes Reporter , Humanos , Imunoprecipitação , Plasmídeos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Viral/genética , Proteínas dos Retroviridae/genética , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Human T-cell leukemia virus type I is the etiological agent of adult T-cell leukemia/lymphoma, an aggressive and fatal lymphoproliferative malignancy. The virus has evolved strategies to escape immune clearance by remaining latent in most infected cells in vivo. We demonstrated previously that virally encoded p30 protein is a potent post-transcriptional inhibitor of virus replication (Nicot, C., Dundr, M., Johnson, J. M., Fullen, J. R., Alonzo, N., Fukumoto, R., Princler, G. L., Derse, D., Misteli, T., and Franchini, G. (2004) Nat. Med. 10, 197-201). p30 is unable to shuttle out of the nucleus in heterokaryon assays, suggesting the existence of specific retention signals. Because suppression of virus replication relies on nuclear retention of the tax/rex mRNA by p30, determining the retention features of p30 will offer hints to break latency in infected cells and insights into new therapeutic approaches. In this study, we used live cell imaging technologies to study the kinetics of p30 and to delineate its retention signals and their function in virus replication. Notably, this is the first study to identify p30 nucleolar retention domains. Using mutants of p30 that localized in different cellular compartments, we show that post-transcriptional control of virus replication by p30 occurs in the nucleoplasm. We further demonstrate that p30 nuclear/nucleolar retention is dependent upon de novo RNA transcripts and interactions with components of the ribosomal machinery.
Assuntos
Nucléolo Celular/virologia , Núcleo Celular/virologia , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , RNA/química , Ribossomos/química , Proteínas não Estruturais Virais/fisiologia , Sequência de Aminoácidos , Animais , Células COS , Chlorocebus aethiops , Cinética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Plasmídeos/metabolismo , Ligação Proteica , Ribossomos/metabolismo , Proteínas não Estruturais Virais/metabolismo , Replicação ViralRESUMO
Whereas adaptive immunity has been extensively studied, very little is known about the innate immunity of the host to HTLV-I infection. HTLV-I-infected ATL patients have pronounced immunodeficiency associated with frequent opportunistic infections, and in these patients, concurrent infections with bacteria and/or parasites are known to increase risks of progression to ATL. The Toll-like receptor-4 (TLR4) activation in response to bacterial infection is essential for dendritic cell maturation and links the innate and adaptive immune responses. Recent reports indicate that TLR4 is targeted by viruses such as RSV, HCV, and MMTV. Here we report that HTLV-I has also evolved a protein that interferes with TLR4 signaling; p30 interacts with and inhibits the DNA binding and transcription activity of PU.1 resulting in the down-regulation of the TLR4 expression from the cell surface. Expression of p30 hampers the release of pro-inflammatory cytokines MCP-1, TNF-alpha, and IL-8 and stimulates release of anti-inflammatory IL-10 following stimulation of TLR4 in human macrophage. Finally, we found that p30 increases phosphorylation and inactivation of GSK3-beta a key step for IL-10 production. Our study suggests a novel function of p30, which may instigate immune tolerance by reducing activation of adaptive immunity in ATL patients.
Assuntos
Citocinas/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/química , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Mediadores da Inflamação/metabolismo , Macrófagos/metabolismo , Proteínas dos Retroviridae/fisiologia , Transdução de Sinais/imunologia , Receptor 4 Toll-Like/antagonistas & inibidores , Animais , Células COS , Proteína de Ligação a CREB/fisiologia , Linhagem Celular , Linhagem Celular Tumoral , Chlorocebus aethiops , Proteínas de Ligação a DNA/antagonistas & inibidores , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/fisiologia , Humanos , Mediadores da Inflamação/fisiologia , Macrófagos/virologia , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-ets/metabolismo , Proteínas dos Retroviridae/metabolismo , Receptor 4 Toll-Like/fisiologia , Transativadores/antagonistas & inibidores , Transativadores/genética , Transativadores/metabolismo , Técnicas do Sistema de Duplo-Híbrido , Fatores de Transcrição de p300-CBP/fisiologiaRESUMO
The antiviral thymidine analog azidothymidine (AZT) is used to treat several virus-associated human cancers. However, to date the mechanism of AZT action remains unclear and thus, reasons for treatment failure are unknown. Adult T-cell leukemia/lymphoma (ATL) is an aggressive malignancy of poor prognosis. Here, we report that enduring AZT treatment of T-cell leukemia virus I-infected cells, in vitro and in vivo in ATL patients, results in inhibition of telomerase activity, progressive telomere shortening, and increased p14(ARF) expression. In turn, this elicits stabilization and reactivation of the tumor suppressor p53-dependent transcription, increased expression of the cyclin-dependent kinase inhibitor p21(Waf1), and accumulation of p27(kip1), thereby inducing cellular senescence and tumor cell death. While ATL patients carrying a wild-type p53 enter remission following treatment with AZT, those with a mutated p53 did not respond, and patients' disease relapse was associated with the selection of a tumor clone carrying mutated inactive p53.
Assuntos
Senescência Celular , Telomerase/antagonistas & inibidores , Proteína Supressora de Tumor p53/fisiologia , Zidovudina/farmacologia , Linhagem Celular Tumoral , Inibidor de Quinase Dependente de Ciclina p21/genética , Inibidor de Quinase Dependente de Ciclina p27 , Vírus Linfotrópico T Tipo 1 Humano , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Leucemia-Linfoma de Células T do Adulto , Mutação , Recidiva , Telômero/efeitos dos fármacos , Transcrição Gênica/efeitos dos fármacos , Células Tumorais Cultivadas , Proteína Supressora de Tumor p14ARF/efeitos dos fármacos , Proteína Supressora de Tumor p53/genética , Zidovudina/uso terapêuticoRESUMO
The segments 10 (S10) of the 11 double stranded RNA genomes from Antheraea mylitta cytoplasmic polyhedrosis virus (AmCPV) encoding a novel polyhedrin polypeptide was converted to cDNA, cloned, and sequenced. Three cDNA clones consisting of 1502 (AmCPV10-1), 1120 (AmCPV10-2), and 1415 (AmCPV10-3) nucleotides encoding polyhedrin of 254, 339, and 319 amino acids with molecular masses of 29, 39, and 37 kDa, respectively, were obtained, and verified by Northern analysis. These clones showed 70-94% sequence identity among them but none with any sequences in databases. The expression of AmCPV10-1 cDNA encoded polyhedrin in Sf-9 cells was detected by immunoblot analysis and formation of polyhedra by electron microscopy, as observed in AmCPV-infected gut cells, but no expression of AmCPV10-2 or AmCPV10-3 cDNA was detected, indicating that during AmCPV replication, along with functional S10 RNA, some defective variant forms of S10 RNAs are packaged in virion particles.
Assuntos
Genes Virais , Mariposas/virologia , Reoviridae/genética , Proteínas Virais/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Clonagem Molecular , DNA Complementar/genética , DNA Viral/genética , Expressão Gênica , Variação Genética , Microscopia Eletrônica de Varredura , Dados de Sequência Molecular , Peso Molecular , Reoviridae/fisiologia , Reoviridae/ultraestrutura , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Spodoptera , Proteínas Virais/química , Proteínas Virais/ultraestrutura , Montagem de Vírus , Replicação ViralRESUMO
In immortal cells, the existence of a mechanism for the maintenance of telomere length is critical. In most cases this is achieved by the reactivation of telomerase, a cellular reverse transcriptase that prevents telomere shortening. Here we report that the telomerase gene (hTERT) promoter is up-regulated during transmission of human T-cell lymphotropic virus type-I (HTLV-I) to primary T cells in vitro and in ex vivo adult T-cell leukemia/lymphoma (ATLL) samples, but not asymptomatic carriers. Although Tax impaired induction of human telomerase reverse transcriptase (hTERT) mRNA in response to mitogenic stimulation, transduction of Tax into primary lymphocytes was sufficient to activate and maintain telomerase expression and telomere length when cultured in the absence of any exogenous stimulation. Transient transfection assays revealed that Tax stimulates the hTERT promoter through the nuclear factor kappaB (NF-kappaB) pathway. Consistently, Tax mutants inactive for NF-kappaB activation could not activate the hTERT or sustain telomere length in transduced primary lymphocytes. Analysis of the hTERT promoter occupancy in vivo using chromatin immunoprecipitation assays suggested that an increased binding of c-Myc and Sp1 is involved in the NF-kappaB-mediated activation of the hTERT promoter. This study establishes the role of Tax in regulation of telomerase expression, which may cooperate with other functions of Tax to promote HTLV-I-associated adult T-cell leukemia.