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1.
J Virol ; 86(8): 4559-65, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22318152

RESUMO

Human T-cell leukemia virus type 1 (HTLV-1) is a complex retrovirus associated with the lymphoproliferative disease adult T-cell leukemia/lymphoma (ATL) and the neurodegenerative disorder tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). Replication of HTLV-1 is under the control of two major trans-acting proteins, Tax and Rex. Previous studies suggested that Tax activates transcription from the viral long terminal repeat (LTR) through recruitment of cellular CREB and transcriptional coactivators. Other studies reported that Rex acts posttranscriptionally and allows the cytoplasmic export of unspliced or incompletely spliced viral mRNAs carrying gag/pol and env only. As opposed to HIV's Rev-responsive element (RRE), the Rex-responsive element (RxRE) is present in all viral mRNAs in HTLV-1. However, based on indirect observations, it is believed that nuclear export and expression of the doubly spliced tax/rex RNA are Rex independent. In this study, we demonstrate that Rex does stimulate Tax expression, through nuclear-cytoplasmic export of the tax/rex RNA, even though a Rex-independent basal export mechanism exists. This effect was dependent upon the RxRE element and the RNA-binding activity of Rex. In addition, Rex-mediated export of tax/rex RNA was CRM1 dependent and inhibited by leptomycin B treatment. RNA immunoprecipitation (RNA-IP) experiments confirmed Rex binding to the tax/rex RNA in both transfected cells with HTLV-1 molecular clones and HTLV-1-infected T cells. Since both Rex and p30 interact with the tax/rex RNA and with one another, this may offer a temporal and dynamic regulation of HTLV-1 replication. Our results shed light on HTLV-1 replication and reveal a more complex regulatory network than previously anticipated.


Assuntos
Produtos do Gene rex/genética , Produtos do Gene tax/genética , Vírus Linfotrópico T Tipo 1 Humano/genética , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , RNA Mensageiro/metabolismo , RNA Viral/metabolismo , Transporte Ativo do Núcleo Celular , Sequência de Aminoácidos , Sequência de Bases , Linhagem Celular , Nucléolo Celular/metabolismo , Regulação Viral da Expressão Gênica , Ordem dos Genes , Produtos do Gene rex/metabolismo , Produtos do Gene tax/metabolismo , Humanos , Dados de Sequência Molecular
2.
J Cancer Sci ; 8(1)2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34938859

RESUMO

The persistence and spreading of HTLV-I infected cells relies upon their clonal expansion through cellular replication. The development of adult T cell leukemia (ATLL) occurs decades following primary infection by HTLV-I. Moreover, identical provirus integration sites have been found in samples recovered several years apart from infected individuals. These observations suggest that infected cells persist in the host for an extended period of time. To endure long term proliferation, HTLV-I pre-leukemic cells must acquire critical oncogenic events, two of which are the bypassing of apoptosis and replicative senescence. In the early stages of disease, interleukin-2 (IL-2)/IL-2R signaling likely plays a major role in combination with activation of anti-apoptotic pathways. Avoidance of replicative senescence in HTLV-I infected cells is achieved through reactivation of human telomerase (hTERT). We have previously shown that HTLV-I viral Tax transcriptionally activates the hTERT promoter. In this study we demonstrate that Tax can stimulate hTERT enzymatic activity independently of its transcriptional effects. We further show that this occurs through Tax-mediated NF-KB activating functions. Our results suggest that in ATLL cells acquire Tax-transcriptional and post-transcriptional events to elevate telomerase activity.

3.
Hand Surg Rehabil ; 40(2): 145-149, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33309790

RESUMO

The rate of failure or recurrence after ulnar nerve release at the elbow is up to 25%. Various biomaterials have been developed to protect nerves from postoperative adhesions. The aim of this study was to review a case series of 40 surgical revision procedures of the ulnar nerve at the elbow, protected by a collagen membrane (Cova™ ORTHO). Forty patients who had this revision surgery between January 2013 and December 2017 were reviewed: 34 were evaluated in person, 6 were evaluated over the phone. The operation consisted in release of the ulnar nerve, anterior subcutaneous transposition and nerve protection using a collagen membrane. We assessed the following parameters with an average follow-up of 4 years and 3 months: paresthesia, night awakening, quality of life (QuickDASH score) and neuropathic pain (DN4 questionnaire). The outcome was determined with the Gabel & Amadio score. The patients' satisfaction was evaluated. A significant decrease in paresthesia and night awakening was found (p < 0.05). The average Gabel & Amadio score improved from 4.4 to 6.7 with 5 excellent, 19 good, 9 fair, and 1 poor result. The average DN4 was 5/10 and the QuickDASH score was 40.1. Eighty percent of patients were satisfied or very satisfied with the outcome. Surgical revision of the ulnar nerve at the elbow remains a delicate operation without a gold standard. This case series found good or excellent results in 70% of patients. Surgical revision of the ulnar nerve with a collagen membrane is a reliable alternative among other possibilities for ulnar nerve release at the elbow.


Assuntos
Articulação do Cotovelo , Síndromes de Compressão do Nervo Ulnar , Colágeno , Cotovelo , Humanos , Qualidade de Vida
4.
J Virol ; 83(22): 11467-76, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19726513

RESUMO

Human T-lymphotropic virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma, and it encodes a number of nonstructural proteins that are involved in virus replication and immune evasion. The viral protein p12 previously has been characterized to interfere with major histocompatibility complex class, ICAM-1, and ICAM-2 expression, and it activates STAT5. Using a previously established T-cell line immortalized with an HTLV-1 molecular clone deleted for p12, we assessed the role of p12 in regulating cellular growth and virus transmission. These cells were complemented for p12 expression by the transduction of a lentivirus vector expressing p12. We report that p12 conferred a selective growth advantage in vitro and increased the colony formation of human T cells in soft-agar assays. Consistently with previous studies, p12- and p12+ cell lines produced similar amounts of virus particles released into the supernatant of cultured cells, although we found that p12 expression greatly enhanced virus transmission. Moreover, we found that interleukin-2 (IL-2) stimulation also increased HTLV-1 transmission whether p12 was expressed or not, and inversely, that the inhibition of Jak signaling significantly reduced HTLV-1 transmission. Intriguingly, IL-2/Jak signaling was not associated with changes in viral gene expression, viral RNA encapsidation, the maturation of the virus particle, cell-cell adherence, or Gag polarization and virological synapse formation. We do demonstrate, however, that IL-2 stimulation and p12 expression significantly increased the rate of syncytium formation, revealing a novel role for IL-2 signaling and Jak activation in HTLV-1 virus transmission.


Assuntos
Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Janus Quinases/fisiologia , Receptores de Interleucina-2/fisiologia , Proteínas Virais Reguladoras e Acessórias/fisiologia , Divisão Celular/fisiologia , Linhagem Celular Tumoral , Transformação Celular Viral/fisiologia , Humanos , Interleucina-2/fisiologia , Proteínas Oncogênicas de Retroviridae/fisiologia , Fatores de Transcrição STAT/fisiologia , Transdução de Sinais/fisiologia , Replicação Viral/fisiologia
5.
Hand Surg Rehabil ; 38(6): 348-352, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31473335

RESUMO

Our hypothesis was that immediate repetition of a microsurgery-suturing task will improve its execution and outcome. This was an experimental animal study. Ten surgeons were divided into two groups of five surgeons. Each performed two end-to-end carotid anastomoses on the same rat, one after the other. The anastomosis was evaluated by the surgeon and an instructor. The primary endpoint was permeability. The outcome was evaluated using an objective and subjective assessment grid yielding 1 to 3 points per item. The total scores for each of the 10 surgeons were used to compare the anastomosis of carotid 1 versus 2, using the ratings given by the surgeon and the instructor. Twenty anastomoses were performed, but 1 rat died intraoperatively, leaving 18 anastomoses for evaluation. No significant differences were found on the main endpoint of permeability, with all anastomoses being permeable. The surgeon's self-assessment was significantly better for the second carotid artery (P=0.05), but this was not confirmed by the proxy assessment (instructor). The analysis by subgroups-morning versus afternoon-found the second carotid anastomosis was significant better in the self-assessment and proxy assessment for the morning group (P<0.001, P=0.024). There was no significant difference in clamping times. The immediate repetition of a microsurgical procedure seems to favor its execution, which leads us to propose that the more difficult or important anastomosis should be done after an easier or less important one during complex surgeries. LEVEL OF EVIDENCE: 2B.


Assuntos
Anastomose Cirúrgica/educação , Competência Clínica , Educação Médica Continuada/métodos , Microcirurgia/educação , Cirurgiões , Suturas , Animais , Artérias Carótidas/cirurgia , Humanos , Ratos Sprague-Dawley , Grau de Desobstrução Vascular
6.
Mol Cell Biol ; 20(22): 8580-9, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11046153

RESUMO

The dysregulation of cellular apoptosis pathways has emerged as a critical early event associated with the development of many types of human cancers. Numerous viral and cellular oncogenes, aside from their inherent transforming properties, are known to induce programmed cell death, consistent with the hypothesis that genetic defects are required to support tumor survival. Here, we report that nuclear expression of the CREB-binding protein (CBP)/p300-binding domain of the human T-cell lymphotropic virus type 1 (HTLV-1) transactivator, Tax, triggers an apoptotic death-inducing signal during short-term clonal analyses, as well as in transient cell death assays. Coexpression of the antiapoptotic factor Bcl-2 increased serum stimulation; incubation with the chemical caspase inhibitor z-Val-Ala-DL-Asp fluoromethylketone antagonized Tax-induced cell death. The CBP/p300-binding defective Tax mutants K88A and V89A exhibited markedly reduced cytotoxic effects compared to the wild-type Tax protein. Importantly, nuclear expression of the minimal CBP/p300-binding peptide of Tax induced apoptosis in the absence of Tax-dependent transcriptional activities, while its K88A counterpart did not cause cell death. Further, Tax-mediated apoptosis was effectively prevented by ectopic expression of the p300 coactivator. We also report that activation of the NF-kappaB transcription pathway by Tax, under growth arrest conditions, results in apoptosis that occurs independent of direct Tax coactivator effects. Our results allude to a novel pivotal role for the transcriptional coactivator p300 in determining cell fate and raise the possibility that dysregulated coactivator usage may pose an early barrier to transformation that must be selectively overcome as a prerequisite for the initiation of neoplasia.


Assuntos
Apoptose/fisiologia , Caspases/metabolismo , Produtos do Gene tax/metabolismo , Proteínas Nucleares/metabolismo , Transativadores/metabolismo , Clorometilcetonas de Aminoácidos/farmacologia , Sequência de Bases , Sítios de Ligação , Inibidores de Caspase , Núcleo Celular/metabolismo , Inibidores de Cisteína Proteinase/farmacologia , Produtos do Gene tax/genética , Células HeLa , Humanos , Dados de Sequência Molecular , Mutação , NF-kappa B/genética , NF-kappa B/metabolismo , Proteínas Nucleares/genética , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Transativadores/genética
7.
Mol Cell Biol ; 21(21): 7391-402, 2001 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11585920

RESUMO

The proto-oncogene c-myb is essential for a controlled balance between cell growth and differentiation. Aberrant c-Myb activity has been reported for numerous human cancers, and enforced c-Myb transcription can transform cells of lymphoid origin by stimulating cellular proliferation and inhibiting apoptotic pathways. Here we demonstrate that activation of the NF-kappaB pathway by the HTLV-1 Tax protein leads to transcriptional inactivation of c-Myb. This conclusion was supported by the fact that Tax mutants unable to stimulate the NF-kappaB pathway could not inhibit c-Myb transactivating functions. In addition, inhibition of Tax-mediated NF-kappaB activation by coexpression of IkappaBalpha restored c-Myb transcription, and Tax was unable to block c-Myb transcription in a NEMO knockout cell line. Importantly, physiological stimuli, such as signaling with the cellular cytokines tumor necrosis factor alpha, interleukin 1 beta (IL-1beta), and lipopolysaccharide, also inhibited c-Myb transcription. These results uncover a new link between extracellular signaling and c-Myb-dependent transcription. The mechanism underlying NF-kappaB-mediated repression was identified as sequestration of the coactivators CBP/p300 by RelA. Interestingly, an amino-terminal deletion form of p300 lacking the C/H1 and KIX domains and unable to bind RelA retained the ability to stimulate c-Myb transcription and prevented NF-kappaB-mediated repression.


Assuntos
Produtos do Gene tax/metabolismo , Proteínas I-kappa B , NF-kappa B/metabolismo , Proteínas Proto-Oncogênicas c-myb/metabolismo , Transcrição Gênica , Animais , Diferenciação Celular , Divisão Celular , Linhagem Celular , Proteínas de Ligação a DNA/metabolismo , Proteína p300 Associada a E1A , Ativação Enzimática , Deleção de Genes , Immunoblotting , Interleucina-1/metabolismo , Ligases/metabolismo , Luciferases/metabolismo , Camundongos , Camundongos Knockout , Microscopia de Fluorescência , Mutação , Inibidor de NF-kappaB alfa , Proteínas Nucleares/metabolismo , Fenótipo , Plasmídeos/metabolismo , Testes de Precipitina , Ligação Proteica , Estrutura Terciária de Proteína , Proto-Oncogene Mas , Coelhos , Reticulócitos/metabolismo , Transdução de Sinais , Transativadores/metabolismo , Ativação Transcricional , Transfecção
8.
Mol Cell Biol ; 18(9): 5052-61, 1998 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9710589

RESUMO

Human T-cell lymphotropic virus type 1 (HTLV-1) transcriptional activation is mediated by the viral transactivator, Tax, and three 21-bp repeats (Tax response element [TxRE]) located in the U3 region of the viral long terminal repeat (LTR). Each TxRE contains a core cyclic AMP response element (CRE) flanked by 5' G-rich and 3' C-rich sequences. The TxRE binds CREB (CRE-binding protein) and Tax to form a ternary complex and confers Tax-dependent transactivation. Recent data indicate that Tax functions as a specific link to connect CREB-binding protein (CBP)/p300 in a phosphorylation-independent manner to CREB/ATF-1 assembled on the viral 21-bp repeats. Glutathione S-transferase pull-down performed with Tax deletion mutants and peptide competition have localized the site in Tax critical for binding CBP/p300 to a highly protease-sensitive region around amino acid residues 81 to 95 (81QRTSKTLKVLTPPIT95) which lies between the domains previously proposed to be important for CREB binding and Tax subunit dimerization. Amino acid residues around the trypsin- and chymotrypsin-sensitive sites (88KVL90) of Tax bear resemblance to those in the kinase-inducible domain of CREB (129SRRPSYRKILNE140) surrounding Ser-133, which undergoes signal-induced phosphorylation to recruit CBP/p300. Site-directed mutagenesis of residues in this domain (R82A, K85A, K88A, and V89A) resulted in proteins which failed to transactivate from the HTLV-1 LTR in vivo. These mutants (K85A, K88A, and V89A) bind CREB with similar affinities as wild-type Tax, yet interaction with CBP/p300 is abrogated in various biochemical assays, indicating that the recruitment of CBP/p300 is crucial for Tax transactivation. A Tax mutant, M47, defective in the COOH-terminal transactivation domain, continued to interact with CBP/p300, suggesting that interactions with additional cellular factors are required for proper Tax function.


Assuntos
Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/química , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Produtos do Gene tax/química , Produtos do Gene tax/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Cloranfenicol O-Acetiltransferase/biossíntese , Clonagem Molecular , Escherichia coli , Produtos do Gene tax/isolamento & purificação , Glutationa Transferase , Células HeLa , Vírus Linfotrópico T Tipo 1 Humano/genética , Humanos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Reação em Cadeia da Polimerase , Conformação Proteica , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/isolamento & purificação , Proteínas Recombinantes de Fusão/metabolismo , Sequências Repetitivas de Ácido Nucleico , Alinhamento de Sequência , Deleção de Sequência , Transfecção
9.
J Hematol Oncol ; 9(1): 121, 2016 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-27829440

RESUMO

BACKGROUND: Human T-cell leukemia virus type 1 (HTLV-1) infection is associated with adult T-cell leukemia/lymphoma (ATLL), a lymphoproliferative malignancy with a dismal prognosis and limited therapeutic options. Recent evidence shows that HTLV-1-transformed cells present defects in both DNA replication and DNA repair, suggesting that these cells might be particularly sensitive to treatment with a small helicase inhibitor. Because the "Werner syndrome ATP-dependent helicase" encoded by the WRN gene plays important roles in both cellular proliferation and DNA repair, we hypothesized that inhibition of WRN activity could be used as a new strategy to target ATLL cells. METHODS: Our analysis demonstrates an apoptotic effect induced by the WRN helicase inhibitor in HTLV-1-transformed cells in vitro and ATL-derived cell lines. Inhibition of cellular proliferation and induction of apoptosis were demonstrated with cell cycle analysis, XTT proliferation assay, clonogenic assay, annexin V staining, and measurement of mitochondrial transmembrane potential. RESULTS: Targeted inhibition of the WRN helicase induced cell cycle arrest and apoptosis in HTLV-1-transformed leukemia cells. Treatment with NSC 19630 (WRN inhibitor) induces S-phase cell cycle arrest, disruption of the mitochondrial membrane potential, and decreased expression of anti-apoptotic factor Bcl-2. These events were associated with activation of caspase-3-dependent apoptosis in ATL cells. We identified some ATL cells, ATL-55T and LMY1, less sensitive to NSC 19630 but sensitive to another WRN inhibitor, NSC 617145. CONCLUSIONS: WRN is essential for survival of ATL cells. Our studies suggest that targeting the WRN helicase with small inhibitors is a novel promising strategy to target HTLV-1-transformed ATL cells.


Assuntos
Leucemia-Linfoma de Células T do Adulto/tratamento farmacológico , Helicase da Síndrome de Werner/antagonistas & inibidores , Apoptose/efeitos dos fármacos , Caspase 3/metabolismo , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Humanos , Leucemia-Linfoma de Células T do Adulto/patologia , Maleimidas/farmacologia , Células Tumorais Cultivadas , Helicase da Síndrome de Werner/fisiologia
10.
Oncogene ; 19(17): 2155-64, 2000 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-10815807

RESUMO

The c-Myb proto-oncogene is preferentially expressed in hematopoietic lineages, and highly expressed in several leukemia types. The Human T-cell Leukemia Virus Type I (HTLV-I) is the etiological agent of Adult T-cell Leukemia/Lymphoma (ATLL). A previous report suggested that Tax, the viral transactivator, is able to suppress the transactivation potential of c-Myb protein by competing for recruitment of CBP. We tested whether such a competition could affect transcription from the c-Myb promoter in Tax expressing T-cells. Using several c-Myb promoter reporter constructs carrying mutations in various regions, we demonstrate that Tax suppression of c-Myb transactivation results in transrepression of the c-Myb promoter through the Myb responsive elements in Jurkat T-cells. The ability of Tax mutants M22, M47 and V89A to interact with the full-length CBP and p300 proteins in vitro, and their ability to repress the c-Myb promoter, was then evaluated. Although both M47 and M22 bind to CBP and p300 to a similar extent, only M47 was able to repress the c-Myb promoter, suggesting that competition for CBP/p300 binding was not the mechanism underlying Tax's effect. This concept was further supported by the fact that the Tax mutant V89A transrepresses the c-Myb promoter efficiently in spite of an impaired binding to CBP and p300. Therefore, Tax-mediated repression of the c-Myb promoter appears to be independent from a direct competition between c-Myb and Tax for recruitment of CBP/p300. Interestingly, a decreased transcription from the endogenous c-Myb promoter was observed in several HTLV-I transformed T-cell lines. Finally, the ability of Tax to directly repress the endogenous c-Myb promoter was demonstrated in a Jurkat cell line stably transfected with a tax gene driven by a cadmium-inducible promoter.


Assuntos
Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Produtos do Gene tax/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/química , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogênicas c-myb/genética , Transativadores/metabolismo , Proteína de Ligação a CREB , Linhagem Celular Transformada , Transformação Celular Viral , Produtos do Gene tax/genética , Humanos , Células Jurkat/patologia , Células Jurkat/virologia , Mutação , Regiões Promotoras Genéticas , Proto-Oncogene Mas , Proteínas Proto-Oncogênicas c-myb/metabolismo , Elementos de Resposta , Transcrição Gênica
11.
Biochim Biophys Acta ; 427(1): 44-56, 1976 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-4112

RESUMO

A comparison of the conformation of Folch-Pi apoprotein in organic solvent and in aqueous solutions has been made by ESR, infrared and circular dichroism spectroscopy studies. Electrophoresis and ultracentrifugation have been carried out in order to correlate molecular weight and charge of the molecule with its conformation. It appears that the protein is monomeric in organic solution. In water, only one component is present but the molecules behave as a polydisperse system of associating molecules. Hydrophobic interacitons seem to be important for this polymerisation which does not appear to be accompanied by the formation of beta-structure. After the transfer of the protein from organic solution to water, the ESR spectra of the protein labelled on the free SH groups show an heterogeneity in the motional environment of the label which permits to assume that different areas of association exist in the polymeric molecule.


Assuntos
Lipoproteínas , Proteínas do Tecido Nervoso , Apoproteínas , Sítios de Ligação , Dicroísmo Circular , Espectroscopia de Ressonância de Spin Eletrônica , Eletroforese em Gel de Poliacrilamida , Concentração de Íons de Hidrogênio , Substâncias Macromoleculares , Matemática , Peso Molecular , Bainha de Mielina , Concentração Osmolar , Ligação Proteica , Conformação Proteica , Marcadores de Spin , Ultracentrifugação
12.
Biochim Biophys Acta ; 420(2): 323-31, 1976 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-1252461

RESUMO

Acrylamide gel electrophoresis in dodecyl sulfate solutions of Folch-Pi apoprotein shows several bands. The different components were separated by Biogel P-200 filtration and then reduced and carboxymethylated. A comparative study of the amino acid composition, N-terminal sequence and C-terminal amino acid of the different components led to the assumption that their primary sequences are similar. Evidence for a contamination of the protein by free amino acids might explain the difference in terminal groups found by us and by other groups. It has been shown that the purified components can polymerize independently of S-S bond formation or exchange. The polymerization products were found to resist dissociation by dodecyl sulfate. It has been suggested therefore that the differences in migration rates of the various components are related to their shape rather than to their molecular weight.


Assuntos
Lipoproteínas , Proteínas do Tecido Nervoso , Sequência de Aminoácidos , Aminoácidos/análise , Animais , Bovinos , Eletroforese em Gel de Poliacrilamida , Peso Molecular
13.
FEBS Lett ; 172(2): 343-7, 1984 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-18072302

RESUMO

The Folch-Pi proteolipid has been isolated from bovine white matter and characterized with respect to phospholipid and glycolipid composition. The protein-lipid complex has been solubilized in aqueous reverse micelles of di(2-ethylhexyl) sodium sulfosuccinate and isooctane. Solubilization of this otherwise water-insoluble proteolipid requires small amounts of water, the percent of solubility being maximum for a low molar ratio of water to surfactant (Wo = 5.6). Unlike hydrophilic proteins, the extent of incorporation into the micellar system is negligible at 50 mM surfactant and reaches 90Vo only at 300 mM. However, the conformation of the proteolipid in reverse micelles as studied by fluorescence emission spectroscopy and circular dichroism was not affected by variations of the surfactant concentration. These results are consistent with the peculiar properties of the aqueous environment of the proteolipid within the reverse micelles and may reflect the membrane-like character of these bio-assemblies.


Assuntos
Proteína Proteolipídica de Mielina/química , Animais , Bovinos , Dicroísmo Circular , Micelas , Conformação Molecular , Espectrometria de Fluorescência , Água
14.
Biochimie ; 61(4): 523-33, 1979.
Artigo em Inglês | MEDLINE | ID: mdl-486582

RESUMO

The highly hydrophobic myelin Folch-Pi apoprotein can be solubilized in organic as well as in aqueous media. In order to understand the molecular organization changes consecutive to changes in the solvent medium, the environment of intrinsic probes and extrinsic labels has been studied by fluorescence and accessibility to some reagents. In acqueous solution, only two tryptophan residues per protein molecule of 23,500 molecular weight have been shown to fluoresce, and their fluorescence characterisitics indicate an hydrophobic and/or constrained environment. Two ANS binding sites have also been observed having a high quenching effect on the intrinsic chromophore fluorescence. A large accessibility has been evidenced for the protein sulfhydryl groups in chloroform-methanol 2:1 (v/v), both by kinetic study of the protein reaction with a specific reagent, N-(1-anilino-naphtyl-4) maleimide, and by the fluorescence characteristics of this probe once linked to the protein. The free sulfhydryl groups were still reactive in acqueous solution, but extrinsic fluorescence of the labelled apoprotein transferred from chloroform-methanol 2:1 (v/v) into water gave evidence of constraints on the probe or on its environment. Such constraints may contribute to the solubilization in acqueous solution of this highly hydrophobic protein.


Assuntos
Apoproteínas/análise , Proteínas da Mielina/análise , Triptofano/análise , Apoproteínas/metabolismo , Soluções Tampão , Cinética , Proteínas da Mielina/metabolismo , Conformação Proteica , Solubilidade , Soluções , Espectrometria de Fluorescência , Espectrofotometria Atômica
15.
Virus Res ; 30(3): 317-34, 1993 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8109163

RESUMO

Human T-cell leukemia virus (HTLV-I) induces adult T cell leukemia/lymphoma (ATL) and a chronic neurological disease named either tropical spastic paraparesis (TSP) or HTLV-I associated myelopathy (HAM). We report here the establishment and characterization of eight HTLV-I-infected lymphoid cell lines derived either from patients with TSP (5) or from asymptomatic carriers (1). Southern blot analysis of T cell beta chain gene rearrangements indicates that all cell lines are composed of clonal populations. The same type of analysis performed with HTLV-I-specific probes showed that they harbor 1 to 5 copies of full length proviruses often associated with deleted proviruses with a restriction map for BamHI, HindIII, PstI and SacI restriction enzymes resembling those of HTLV-I previously isolated from Japan and Caribbean area. One of the cell lines, 2060, derived from a TSP patient was shown to express a relative large amount of virus easily transmissible to fresh peripheral and cord blood lymphocytes. The full length proviral genome contained in this cell line was cloned and used in transient expression experiments. We showed that the cloned provirus was able to direct the synthesis of the major structural viral proteins, the protease and the tax and rex regulatory proteins. The structural viral proteins could be assembled into free particles detected in the culture medium of transfected cells. Although the infectivity of these viral particles remains to be determined, this new clone can be employed to examine the cell types in which this TSP-derived provirus directs viral protein synthesis and eventually replicates. It should also prove of value in studies on the early cellular events induced by viral products.


Assuntos
Infecções por HTLV-I/microbiologia , Vírus Linfotrópico T Tipo 1 Humano , Animais , Sequência de Bases , Linhagem Celular , Chlorocebus aethiops , Clonagem Molecular , DNA Viral/genética , Guiana Francesa , Expressão Gênica , Genes env , Vírus Linfotrópico T Tipo 1 Humano/genética , Vírus Linfotrópico T Tipo 1 Humano/isolamento & purificação , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Humanos , Martinica , Microscopia Eletrônica , Dados de Sequência Molecular , Provírus/genética , Provírus/isolamento & purificação , Provírus/fisiologia , Integração Viral , Replicação Viral
16.
AIDS Res Hum Retroviruses ; 16(16): 1629-32, 2000 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-11080802

RESUMO

The B-myb gene was identified on the basis of its homology with the protooncogene c-myb, homolog of the avian myeloblastosis virus (AMV) and avian leukemia virus (E26) transforming genes. Several studies using antisense constructs or antisense oligonucleotides as well as overexpression experiments suggest that B-Myb plays an important role in the transition from G(1) to S phase of the cell cycle and that B-Myb expression is cell cycle regulated. We have previously demonstrated that the human T cell lymphotropic virus type 1 (HTLV1) trans-activator Tax is able to repress transcription from c-myb promoter reporter constructs as well as from the endogenous c-myb promoter in human T cells and that this effect is mediated through inhibition of the c-Myb trans-activating functions. Here we report that both HTLV-1 as well as HTLV-2 Tax proteins inhibit c-Myb trans-activation in mouse embryo fibroblasts (MEFs). In addition to c-Myb, B-Myb expression is also markedly downregulated in HTLV-1-transformed cells at both RNA and protein levels. Furthermore, by using a Jurkat T cell line stably transfected with a tax gene driven by a cadmium-inducible promoter (JPX9), we were able to demonstrate that Tax directly represses the endogenous B-myb promoter in T cells. Because c-Myb and B-Myb have been involved in cell cycle progression, our results suggest that Tax, by repressing both c-Myb and B-Myb endogenous promoters, may bypass their requirement for cell cycle progression in HTLV-1-transformed T cells.


Assuntos
Proteínas de Ciclo Celular , Proteínas de Ligação a DNA/genética , Produtos do Gene tax/farmacologia , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Vírus Linfotrópico T Tipo 2 Humano/fisiologia , Linfócitos T/virologia , Transativadores/genética , Ativação Transcricional , Animais , Linhagem Celular Transformada , Transformação Celular Viral , Proteínas de Ligação a DNA/metabolismo , Embrião de Mamíferos/citologia , Fibroblastos , Humanos , Células Jurkat , Camundongos , Regiões Promotoras Genéticas , Transativadores/metabolismo
17.
AIDS Res Hum Retroviruses ; 16(16): 1677-81, 2000 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-11080809

RESUMO

Human T cell lymphotropic virus type II (HTLV-2) was originally isolated from a patient with a hairy T cell leukemia. It has been associated with rare cases of CD8(+) T lymphoproliferative disorders, and has a controversial role as a pathogen. The loss of p53 function, as a consequence of mutation or inactivation, increases the chances of genetic damage. Indeed, the importance of p53 as a tumor suppressor is evident from the fact that over 60% of all human cancers have a mutant or inactive p53. p53 status has been extensively studied in HTLV-1-infected cell lines. Interestingly, despite the fact that p53 mutations have been found in only a minority of cells, the p53 functions were found to be impaired. We have analyzed the functional activity of the p53 tumor suppressor in cells transformed with HTLV-2 subtypes A and B. As with HTLV-1-infected cells, abundant levels of the p53 protein are detected in HTLV-2 virus-infected cell lines. Using p53 reporter plasmid or induction of p53-responsive genes in response to gamma-irradiation, the p53 was found to be transcriptionally inhibited in HTLV-2-infected cells. Interestingly, although Tax-2A and-2B inactivate p53, the Tax-2A protein appears to inhibit p53 function less efficiently than either Tax-1 or Tax-2B in T cells, but not in fibroblasts.


Assuntos
Produtos do Gene tax/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Vírus Linfotrópico T Tipo 2 Humano/fisiologia , Proteína Supressora de Tumor p53/antagonistas & inibidores , Proteína Supressora de Tumor p53/metabolismo , Animais , Linhagem Celular Transformada , Infecções por HTLV-I/virologia , Infecções por HTLV-II/virologia , Humanos , Camundongos , Linfócitos T/virologia , Transcrição Gênica , Ativação Transcricional , Proteína Supressora de Tumor p53/genética
18.
AIDS Res Hum Retroviruses ; 16(16): 1777-81, 2000 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-11080826

RESUMO

Human T cell leukemia/lymphotropic virus types 1 and 2 are two immunologically and phylogenetically related retroviruses that differ in their pathogenicity in vivo. The overall genetic structure of HTLV-1 and -2 is similar. Each contains a unique region at the 3' end of the genome, designated the pX region. p12(I) is a membrane-associated protein encoded by the open reading frame I (ORF I) region of HTLV-1, which lies within the pX region. A corresponding protein, p10(I) is encoded by the ORF I region of HTLV-2 and an additional protein, p11(V), is encoded by ORF V, which overlaps the HTLV-2 ORF I region. As with HTLV-1, the small proteins encoded by the pX region of HTLV-2 appear to be dispensable for viral replication and cellular transformation in vitro. However, the small open reading frames of both viruses are important for viral replication in vivo, which suggests they may play an important role during the viral life cycle. This study was undertaken to investigate and compare the cellular targets of the p10(I), p11(V), and p12(I) putative proteins.


Assuntos
Antígenos de Histocompatibilidade Classe I/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , Vírus Linfotrópico T Tipo 2 Humano/metabolismo , Proteínas dos Retroviridae/genética , Proteínas dos Retroviridae/metabolismo , Regiões 3' não Traduzidas/genética , Linhagem Celular Transformada , Infecções por HTLV-I/virologia , Infecções por HTLV-II/virologia , Células HeLa , Vírus Linfotrópico T Tipo 1 Humano/genética , Vírus Linfotrópico T Tipo 1 Humano/patogenicidade , Vírus Linfotrópico T Tipo 2 Humano/genética , Vírus Linfotrópico T Tipo 2 Humano/patogenicidade , Humanos , ATPases Translocadoras de Prótons/metabolismo , Receptores de Interleucina-2/metabolismo , Linfócitos T/virologia
19.
Maturitas ; 37(2): 95-104, 2000 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-11137328

RESUMO

OBJECTIVE: To assess the biological safety of four hormone replacement treatment (HRT) combinations in women with non insulin dependent diabetes mellitus (NIDDM) or impaired glucose tolerance (IGT). SUBJECTS AND METHODS: Randomized, double-blind, placebo-controlled trial to analyze the variation of fibrinogen, factor VII, PAI1, and TG blood levels in women (n=99), with NIDDM or IGT, receiving a 3-month course of either oral oestradiol (1 or 2 mg) combined with Chlormadinone Acetate 5 mg, or transdermal oestradiol 50 microg/24 h in association with Norethisterone Acetate (11.2 or 22.4 mg), or placebo. Follow-up lasted 3 months. RESULTS: Ninety nine patients, mean age 56 years (SD 5), mean diabetes duration 7 years (S.D. 7), mean glycated hemoglobin (7.3%) were enrolled. There was no significant difference between the groups for any of the primary hemostasis criteria (n=77). Triglycerides (TG) variation significantly differed between groups, P=0.01, from -21% in the large patch group, to +22% in the placebo group (n=82). Treatment administration routes did not significantly differ for any of the criteria. There was a significant difference in the total cholesterol variation between groups, from +8.7% in the placebo group to -10.8% in the oral 1 mg group (P=0.001). CONCLUSION: The treatments had no highly deleterious effect in these patients with NIDDM or with IGT. Long-term trials can be performed with such patients, and an hormone treatment can be prescribed to relieve symptoms. Since these patients had a well-controlled NIDDM, results might be different in less well-controlled diabetes. The data do not support the hypothesis of an impaired oestrogen effect in patients with NIDDM.


Assuntos
Diabetes Mellitus Tipo 2/sangue , Estrogênios/uso terapêutico , Intolerância à Glucose/sangue , Terapia de Reposição Hormonal/métodos , Biomarcadores/sangue , Acetato de Clormadinona/administração & dosagem , Método Duplo-Cego , Quimioterapia Combinada , Estrogênios/administração & dosagem , Estrogênios/efeitos adversos , Feminino , Terapia de Reposição Hormonal/efeitos adversos , Humanos , Consentimento Livre e Esclarecido , Pessoa de Meia-Idade , Noretindrona/administração & dosagem , Noretindrona/análogos & derivados , Acetato de Noretindrona , Pós-Menopausa/sangue
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