Assuntos
Anticorpos Monoclonais/uso terapêutico , Hemoglobinúria Paroxística/tratamento farmacológico , Falência Renal Crônica/terapia , Diálise Renal , Adulto , Anticorpos Monoclonais Humanizados , Hemoglobinúria Paroxística/complicações , Humanos , Falência Renal Crônica/complicações , Masculino , Resultado do TratamentoRESUMO
In addition to promoting cell survival, neurotrophins also can elicit apoptosis in restricted cell types. Recent results indicate that nerve growth factor (NGF) can induce Schwann cell death via engagement of the p75 neurotrophin receptor. Here we describe a novel interaction between the p75 receptor and receptor-interacting protein 2, RIP2 (RICK/CARDIAK), that accounts for the ability of neurotrophins to choose between a survival-versus-death pathway. RIP2, an adaptor protein with a serine threonine kinase and a caspase recruitment domain (CARD), is highly expressed in dissociated Schwann cells and displays an endogenous association with p75. RIP2 binds to the death domain of p75 via its CARD domain in an NGF-dependent manner. The introduction of RIP2 into Schwann cells deficient in RIP2 conferred NGF-dependent nuclear transcription factor-kappaB (NF-kappaB) activity and decreased the cell death induced by NGF. Conversely, the expression of a dominant-negative version of RIP2 protein resulted in a loss of NGF-induced NF-kappaB induction and increased NGF-mediated cell death. These results indicate that adaptor proteins like RIP2 can provide a bifunctional switch for cell survival or cell death decisions mediated by the p75 neurotrophin receptor.
Assuntos
Caspases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Receptores de Fator de Crescimento Neural/metabolismo , Fator 2 Ativador da Transcrição , Animais , Apoptose/fisiologia , Western Blotting , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Células Cultivadas , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Genes Dominantes , Glutationa Transferase/genética , Proteínas de Fluorescência Verde , Humanos , Rim/citologia , Rim/metabolismo , Ligantes , Proteínas Luminescentes/genética , NF-kappa B/metabolismo , Fator de Crescimento Neural/farmacologia , Ligação Proteica/fisiologia , Proteínas Serina-Treonina Quinases/deficiência , Proteínas Serina-Treonina Quinases/genética , Estrutura Terciária de Proteína/fisiologia , Proteínas/genética , Proteínas/metabolismo , Ratos , Receptor de Fator de Crescimento Neural , Proteína Serina-Treonina Quinase 2 de Interação com Receptor , Proteína Serina-Treonina Quinases de Interação com Receptores , Receptores de Fator de Crescimento Neural/genética , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Células de Schwann/citologia , Células de Schwann/efeitos dos fármacos , Células de Schwann/metabolismo , Fator 6 Associado a Receptor de TNF , Fatores de Transcrição/metabolismo , TransfecçãoRESUMO
Neurotrophins rely on Trk tyrosine kinase and p75 receptors for signal transduction. Recently, other roles for these receptors have been identified. Many questions have been raised about the mechanism by which these receptors mediate diverse cellular functions. Studies indicate a great deal of neurotrophin signaling specificity may stem from ligand-receptor selectivity and intracellular protein recruitment.
Assuntos
Antígenos CD/fisiologia , Proteínas de Neoplasias , Fosfoproteínas , Receptores de Fator de Crescimento Neural/fisiologia , Receptores do Fator de Necrose Tumoral/fisiologia , Animais , Antígenos CD/efeitos dos fármacos , Antígenos de Neoplasias , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Contagem de Células , Proteínas de Ligação a DNA/fisiologia , Humanos , Ligantes , Substâncias Macromoleculares , Proteínas de Membrana/fisiologia , Fatores de Crescimento Neural/fisiologia , Proteínas do Tecido Nervoso/fisiologia , Neurônios/metabolismo , Receptores de Fator de Crescimento Neural/classificação , Receptores de Fator de Crescimento Neural/efeitos dos fármacos , Receptores do Fator de Necrose Tumoral/efeitos dos fármacos , Receptores Tipo II do Fator de Necrose Tumoral , Células de Schwann/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Fator de Necrose Tumoral alfa/fisiologiaRESUMO
The Akt family of serine/threonine-directed kinases promotes cellular survival in part by phosphorylating and inhibiting death-inducing proteins. Here we describe a novel functional interaction between Akt and apoptosis signal-regulating kinase 1 (ASK1), a mitogen-activated protein kinase kinase kinase. Akt decreased ASK1 kinase activity stimulated by both oxidative stress and overexpression in 293 cells by phosphorylating a consensus Akt site at serine 83 of ASK1. Activation of the phosphoinositide 3-kinase (PI3-K)/Akt pathway also inhibited the serum deprivation-induced activity of endogenous ASK1 in L929 cells. An association between Akt and ASK1 was detected in cells by coimmunoprecipitation. Phosphorylation by Akt inhibited ASK1-mediated c-Jun N-terminal kinase and activating transcription factor 2 activities in intact cells. Finally, activation of the PI3-K/Akt pathway reduced apoptosis induced by ASK1 in a manner dependent on phosphorylation of serine 83 of ASK1. These results provide the first direct link between Akt and the family of stress-activated kinases.
Assuntos
MAP Quinase Quinase Quinases/metabolismo , Proteínas Serina-Treonina Quinases , Proteínas Proto-Oncogênicas/metabolismo , Sequência de Aminoácidos , Apoptose , Linhagem Celular , Sobrevivência Celular , Células HeLa , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno , MAP Quinase Quinase Quinase 5 , MAP Quinase Quinase Quinases/química , MAP Quinase Quinase Quinases/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Proteínas Proto-Oncogênicas c-akt , Serina/química , Transdução de Sinais , Especificidade por SubstratoRESUMO
The p75 receptor is the founding member of the TNF receptor superfamily. Members in this receptor family share a common cysteine motif repeated two to six times that serves as the ligand binding domain. In addition, several members contain a cytoplasmic region designated the death domain. The neurotrophins NGF, BDNF, NT-3, and NT-4 each bind to the p75 receptor and also more selectively to members of the Trk family of receptor tyrosine kinases. Although the biological functions of p75 have been elusive, recent experimental evidence supports an involvement of this receptor in apoptosis. This presents a counter-intuitive function for neurotrophins, which are normally required for the survival of neurons during development. The life-and-death decisions by neurotrophins appear to be governed by the level of expression and signaling activities of the p75 and Trk tyrosine kinase receptors and their downstream effector molecules. The generation of the correct number of cells in the nervous system is a highly controlled and coordinated process that is the consequence of cell proliferation and cell death decisions. The appropriate number of neuronal and glial cells formed during development guarantees the establishment of proper innervation and functional synaptic connections. One common mechanism to account for the number of viable cells is the ability to form ligand-receptor complexes that promote cell survival under conditions of limiting concentrations of trophic factors. Another diametrically opposed mechanism is to produce ligand-receptor interactions that can activate programmed cell death directly.
Assuntos
Apoptose/fisiologia , Proteínas de Drosophila , Proteínas de Insetos/metabolismo , Proteínas Quinases Ativadas por Mitógeno , Receptores de Fator de Crescimento Neural/fisiologia , Animais , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Diferenciação Celular , Sobrevivência Celular , Humanos , Camundongos , Camundongos Knockout , Proteína Quinase 1 Ativada por Mitógeno , Proteína Quinase 6 Ativada por Mitógeno , Fatores de Crescimento Neural/metabolismo , Neurônios/fisiologia , Receptores Proteína Tirosina Quinases/metabolismo , Receptor do Fator Neutrófico Ciliar , Receptor de Fator de Crescimento Neural , Receptores de Fator de Crescimento Neural/deficiência , Receptores de Fator de Crescimento Neural/metabolismoRESUMO
In addition to the Trk tyrosine kinase receptors, neurotrophins also bind to a second receptor, p75, a member of the tumor necrosis factor receptor superfamily. Several signaling pathways have been implicated for p75 in the absence of Trk receptors, including induction of NF-kappaB and c-Jun kinase activities and increased production of ceramide. However, to date, the mechanisms by which the p75 receptor initiates intracellular signal transduction have not been defined. Here we report a specific interaction between p75 and TRAF6 (tumor necrosis factor receptor-associated factor-6) after transient transfection in HEK293T cells. The interaction was ligand-dependent and maximal at 100 ng/ml of nerve growth factor (NGF). Other neurotrophins also promoted the association of TRAF6 with p75 but to a lesser extent. The binding of TRAF6 was localized to the juxtamembrane region of p75 by co-immunoprecipitation and Western blotting. To assess the functional significance of this interaction, we have tested responses in cultured Schwann cells that express p75 and TRAF6. An NGF-mediated increase in the nuclear localization of the p65 subunit of NF-kappaB could be blocked by the introduction of a dominant negative form of TRAF6 in Schwann cells. These results indicate that TRAF6 can potentially function as a signal transducer for NGF actions through the p75 receptor.
Assuntos
Proteínas/metabolismo , Receptores de Fator de Crescimento Neural/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Transdução de Sinais , Linhagem Celular , Humanos , NF-kappa B/metabolismo , Ligação Proteica , Receptor de Fator de Crescimento Neural , Células de Schwann/metabolismo , Fator 6 Associado a Receptor de TNF , TransfecçãoRESUMO
Toxic oil syndrome (TOS) was caused by the consumption of rapeseed oil contaminated with derivatives of aniline. Many persons who survived the acute phase developed a puzzling, multi-year chronic disease considered to be inflammatory or autoimmune in nature. In attempting to characterize their autoantibodies, we found that 74% of TOS patients with chronic disease had IgG antibodies to C-reactive protein (CRP). This activity was detectable only when CRP was chemically or physically denatured and behaved like a previously described antibody produced by immunization with the CRP monomer. Significant antibody reactivities to other acute phase proteins, especially alpha 1-antitrypsin and fibrinogen (P < 0.025) and ceruloplasmin (P < 0.05) were also observed. IgG antibodies to cryptic epitopes in CRP and other major serum proteins that increase during the acute phase response may reflect an earlier toxin-mediated insult to the liver that included abnormal biosynthesis of and/or damage to acute phase proteins.
Assuntos
Proteínas de Fase Aguda/imunologia , Autoanticorpos/imunologia , Autoantígenos/imunologia , Doenças Autoimunes/induzido quimicamente , Brassica , Proteína C-Reativa/imunologia , Epitopos/imunologia , Óleos de Plantas/efeitos adversos , Compostos de Anilina/intoxicação , Doenças Autoimunes/epidemiologia , Doenças Autoimunes/imunologia , Ceruloplasmina/imunologia , Doença Crônica , Reações Cruzadas , Ácidos Graxos Monoinsaturados , Fibrinogênio/imunologia , Intoxicação/epidemiologia , Intoxicação/imunologia , Desnaturação Proteica , Óleo de Brassica napus , Espanha/epidemiologia , alfa 1-Antitripsina/imunologiaRESUMO
Drug-induced lupus is a serious side effect of certain medications, but the chemical features that confer this property and the underlying pathogenesis are puzzling. Prototypes of all six therapeutic classes of lupus-inducing drugs were highly cytotoxic only in the presence of activated neutrophils. Removal of extracellular hydrogen peroxide before, but not after, exposure of the drug to activated neutrophils prevented cytotoxicity. Neutrophil-dependent cytotoxicity required the enzymatic action of myeloperoxidase, resulting in the chemical transformation of the drug to a reactive product. The capacity of drugs to serve as myeloperoxidase substrates in vitro was associated with the ability to induce lupus in vivo.