Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 5 de 5
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Immunol ; 180(1): 590-600, 2008 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-18097061

RESUMO

The leukocyte integrins have critical roles in host defense and inflammatory tissue injury. We found that integrin alphaDbeta2, a novel but largely uncharacterized member of this family, is restricted to subsets of macrophages and a small population of circulating leukocytes in wild-type mice in the absence of inflammatory challenge and is expressed in regulated fashion during cytokine-induced macrophage differentiation in vitro. alphaDbeta2 is highly displayed on splenic red pulp macrophages and mediates their adhesion to local targets, identifying key functional activity. In response to challenge with Plasmodium berghei, a malarial pathogen that models systemic infection and inflammatory injury, new populations of alphaD+ macrophages evolved in the spleen and liver. Unexpectedly, targeted deletion of alphaD conferred a survival advantage in P. berghei infection over a 30-day observation period. Mechanistic studies demonstrated that the increased survival of alphaD-/- animals at these time points is not attributed to differences in magnitude of anemia or parasitemia or to alterations in splenic microanatomy, each of which is a key variable in the natural history of P. berghei infection, and indicated that an altered pattern of inflammatory cytokines may contribute to the difference in mortality. In contrast to the outcome in malarial challenge, death of alphaD-/- animals was accelerated in a model of Salmonella sepsis, demonstrating differential rather than stereotyped roles for alphaDbeta2 in systemic infection. These studies identify previously unrecognized and unique activities of alphaDbeta2, and macrophages that express it, in host defense and injury.


Assuntos
Antígenos CD11/metabolismo , Cadeias alfa de Integrinas/metabolismo , Macrófagos/imunologia , Malária/imunologia , Plasmodium berghei , Salmonella , Sepse/imunologia , Animais , Antígenos CD11/genética , Citocinas/metabolismo , Inflamação/imunologia , Cadeias alfa de Integrinas/genética , Fígado/imunologia , Ativação de Macrófagos , Malária/mortalidade , Camundongos , Camundongos Knockout , Sepse/mortalidade , Baço/imunologia
2.
BMC Cancer ; 5: 125, 2005 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-16202132

RESUMO

BACKGROUND: The transcription factor activator protein-1 (AP-1) has been implicated in a large variety of biological processes including oncogenic transformation. The tyrosine kinases of the epidermal growth factor receptor (EGFR) constitute the beginning of one signal transduction cascade leading to AP-1 activation and are known to control cell proliferation and differentiation. Drug discovery efforts targeting this receptor and other pathway components have centred on monoclonal antibodies and small molecule inhibitors. Resistance to such inhibitors has already been observed, guiding the prediction of their use in combination therapies with other targeted agents such as RNA interference (RNAi). This study examines the use of RNAi and kinase inhibitors for qualification of components involved in the EGFR/AP-1 pathway of ME180 cells, and their inhibitory effects when evaluated individually or in tandem against multiple components of this important disease-related pathway. METHODS: AP-1 activation was assessed using an ME180 cell line stably transfected with a beta-lactamase reporter gene under the control of AP-1 response element following epidermal growth factor (EGF) stimulation. Immunocytochemistry allowed for further quantification of small molecule inhibition on a cellular protein level. RNAi and RT-qPCR experiments were performed to assess the amount of knockdown on an mRNA level, and immunocytochemistry was used to reveal cellular protein levels for the targeted pathway components. RESULTS: Increased potency of kinase inhibitors was shown by combining RNAi directed towards EGFR and small molecule inhibitors acting at proximal or distal points in the pathway. After cellular stimulation with EGF and analysis at the level of AP-1 activation using a beta-lactamase reporter gene, a 10-12 fold shift or 2.5-3 fold shift toward greater potency in the IC50 was observed for EGFR and MEK-1 inhibitors, respectively, in the presence of RNAi targeting EGFR. CONCLUSION: EGFR pathway components were qualified as targets for inhibition of AP-1 activation using RNAi and small molecule inhibitors. The combination of these two targeted agents was shown to increase the efficacy of EGFR and MEK-1 kinase inhibitors, leading to possible implications for overcoming or preventing drug resistance, lowering effective drug doses, and providing new strategies for interrogating cellular signalling pathways.


Assuntos
Inibidores Enzimáticos/farmacologia , Regulação Enzimológica da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Interferência de RNA , Anticorpos Monoclonais/química , Butadienos/farmacologia , Diferenciação Celular , Proliferação de Células , Relação Dose-Resposta a Droga , Fator de Crescimento Epidérmico/metabolismo , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/metabolismo , Genes Reporter , Humanos , Imuno-Histoquímica , Concentração Inibidora 50 , MAP Quinase Quinase 1/antagonistas & inibidores , Nitrilas/farmacologia , Oligonucleotídeos Antissenso/farmacologia , Fosforilação , Quinazolinas , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais , Fator de Transcrição AP-1/farmacologia , Transfecção , Tirfostinas/farmacologia , beta-Lactamases/metabolismo
3.
Cell ; 122(3): 379-91, 2005 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-16096058

RESUMO

Platelets are specialized hemostatic cells that circulate in the blood as anucleate cytoplasts. We report that platelets unexpectedly possess a functional spliceosome, a complex that processes pre-mRNAs in the nuclei of other cell types. Spliceosome components are present in the cytoplasm of human megakaryocytes and in proplatelets that extend from megakaryocytes. Primary human platelets also contain essential spliceosome factors including small nuclear RNAs, splicing proteins, and endogenous pre-mRNAs. In response to integrin engagement and surface receptor activation, platelets precisely excise introns from interleukin-1beta pre-mRNA, yielding a mature message that is translated into protein. Signal-dependent splicing is a novel function of platelets that demonstrates remarkable specialization in the regulatory repertoire of this anucleate cell. While this mechanism may be unique to platelets, it also suggests previously unrecognized diversity regarding the functional roles of the spliceosome in eukaryotic cells.


Assuntos
Processamento Alternativo , Plaquetas/citologia , Núcleo Celular/metabolismo , Precursores de RNA/metabolismo , Transdução de Sinais/fisiologia , Plaquetas/metabolismo , Plaquetas/ultraestrutura , Núcleo Celular/genética , Citoplasma/genética , Citoplasma/metabolismo , Citoplasma/ultraestrutura , Células HeLa , Humanos , Interleucina-1/genética , Interleucina-1/metabolismo , Megacariócitos/citologia , Megacariócitos/metabolismo , Megacariócitos/ultraestrutura , Precursores de RNA/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transdução de Sinais/genética , Spliceossomos/genética , Spliceossomos/metabolismo , Transcrição Gênica/genética
4.
FEBS Lett ; 512(1-3): 291-7, 2002 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-11852098

RESUMO

Friedreich ataxia is the consequence of frataxin deficiency, most often caused by a GAA repeat expansion in intron 1 of the corresponding gene. Frataxin is a mitochondrial protein involved in iron homeostasis. As an attempt to generate a mouse model of the disease, we introduced a (GAA)(230) repeat within the mouse frataxin gene by homologous recombination. GAA repeat knockin mice were crossed with frataxin knockout mice to obtain double heterozygous mice expressing 25-36% of wild-type frataxin levels. These mice were viable and did not develop anomalies of motor coordination, iron metabolism or response to iron loading. Repeats were meiotically and mitotically stable.


Assuntos
Ataxia de Friedreich/genética , Proteínas de Ligação ao Ferro , Camundongos Mutantes , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Expansão das Repetições de Trinucleotídeos/genética , Alelos , Animais , Homeostase , Ferro/metabolismo , Camundongos , Mitocôndrias/metabolismo , Frataxina
5.
Curr Opin Hematol ; 9(1): 30-5, 2002 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11753075

RESUMO

Leukocyte adhesion deficiency (LAD) syndromes are failures of innate host defenses against bacteria, fungi, and other microorganisms resulting from defective tethering, adhesion, and targeting of myeloid leukocytes to sites of microbial invasion. LAD I and variant LAD I syndromes are caused by mutations that impair expression or function of integrins of the beta 2 class (CD11/CD18 integrins, or "leukocyte" integrins). In contrast, subjects with LAD II have similar clinical features but intact leukocyte integrin expression and function. The molecular basis for LAD II is defective glycosylation of ligands on leukocytes recognized by the selectin family of adhesion molecules as well as defective glycosylation of other glycoconjugates. The defect has recently been attributed to mutations in a novel fucose transporter localized to the Golgi apparatus. Establishing the molecular basis for LAD syndromes has generated insights into mechanisms of leukocyte accumulation relevant to a broad variety of immunodeficiency syndromes as well as to diseases and disorders of unregulated inflammation that result in tissue damage.


Assuntos
Antígenos CD18/fisiologia , Adesão Celular , Síndrome da Aderência Leucocítica Deficitária/imunologia , Leucócitos/imunologia , Selectinas/metabolismo , Antígenos CD18/genética , Endotélio Vascular/metabolismo , Glicosilação , Humanos , Integrinas/agonistas , Integrinas/fisiologia , Síndrome da Aderência Leucocítica Deficitária/genética , Ligantes , Modelos Imunológicos , Mutação , Selectinas/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...