RESUMEN
Transcription of the heat shock protein Hsp90alpha was strongly upregulated in human T-cells by interleukin-4 (IL-4) and to a lesser extent by IL-2, reaching peak levels after 2-3 days of stimulation. Heat shock proteins are induced within minutes under stress conditions, via heat shock factors (HSF), which activate heat shock elements (HSE). IL-4, IL-2 and IL-13 upregulated transcription of a reporter gene coupled to a single HSE site and a minimal promoter. HSE may therefore be involved in cytokine induced heat shock gene transcription in the absence of cellular stress.
Asunto(s)
Proteínas HSP90 de Choque Térmico/genética , Respuesta al Choque Térmico/genética , Interleucina-4/farmacología , Transcripción Genética/fisiología , Secuencia de Bases , Células Cultivadas , Cloranfenicol O-Acetiltransferasa/genética , Regulación de la Expresión Génica , Genes Reporteros/genética , Humanos , Interleucina-2/farmacología , Datos de Secuencia Molecular , Regiones Promotoras Genéticas/genética , ARN Mensajero/biosíntesis , Linfocitos T , Células Tumorales Cultivadas , Regulación hacia ArribaRESUMEN
IL-4 signals on lymphocytes and other cells through a heterodimeric complex of two cytokine receptor proteins, IL-4R alpha and gamma C. IL-4 variants with mutations in the positions Tyr124, and (less efficiently) Arg121 and Ser125 are deficient in interaction with gamma zero and can be applied as IL-4 antagonists. Some cells respond to IL-4 without using gamma zero presumably by recruiting an alternative subunit into the receptor complex. We have investigated the effects of IL-4 mutant proteins on cells bearing this second type of IL-4 receptor complex. Mutations in the amino acid residues Arg 121 and Tyr124, but not Ser125, completely prevented cellular responses mediated by type 2 IL-4 receptors. Both receptor types are therefore affected by mutations in an overlapping but not identical site of the IL-4 molecule.
Asunto(s)
Antígenos CD/análisis , Antígenos CD/metabolismo , Interleucina-4/antagonistas & inhibidores , Interleucina-4/metabolismo , Mutación/inmunología , Fragmentos de Péptidos/inmunología , Receptores de Interleucina/análisis , Receptores de Interleucina/metabolismo , Antígenos CD/genética , Carcinoma de Células Renales , División Celular/efectos de los fármacos , División Celular/genética , División Celular/inmunología , Inhibidores de Crecimiento/farmacología , Humanos , Interleucina-4/genética , Ligandos , Datos de Secuencia Molecular , Receptores de Interleucina/genética , Receptores de Interleucina-4 , Factor de Transcripción STAT6 , Transactivadores/farmacología , Transcripción Genética/inmunología , Células Tumorales CultivadasRESUMEN
Class switching to IgE is preceded by the appearance of epsilon germline transcripts, which are induced by interleukin-4 (IL-4) and by IL-13. A 51-bp fragment of the human epsilon germline promoter conferred in reporter gene assays with the erythroleukemic cell line TF-1 upregulation of transcription by IL-4 or IL-13, and repression by interferon-alpha (IFN-alpha) and IFN-gamma. A central IFN-gamma activated sequence within the 51-bp fragment was sufficient for transcriptional regulation by the cytokines in the absence of its normal flanking regions. In contrast, deletion of either upstream or downstream sequences abolished repression by IFN-alpha or INF-gamma, but not upregulation by IL-4 or IL-13. IL-4 stimulated reporter gene transcription required more than ten times higher concentrations than cell proliferation or tyrosine phosphorylation of the IL-4 receptor.
Asunto(s)
Citocinas/farmacología , Inmunoglobulina E/genética , Regiones Promotoras Genéticas/efectos de los fármacos , Diversidad de Anticuerpos , Secuencia de Bases , Sitios de Unión/genética , Línea Celular , ADN/genética , Elementos de Facilitación Genéticos , Humanos , Región de Cambio de la Inmunoglobulina , Interferón-alfa/farmacología , Interferón gamma/farmacología , Interleucina-13/farmacología , Interleucina-4/farmacología , Datos de Secuencia Molecular , Regulación hacia ArribaRESUMEN
We characterize here a highly efficient antagonist for interleukin-4 (IL-4) in the mouse system. In this double mutant of the murine IL-4 protein, both glutamine 116 and tyrosine 119 were substituted by aspartic acid residues. This variant (QY) bound with similar affinity to the IL-4 receptor alpha subunit as wild type IL-4 without inducing cellular responses. In contrast, QY completely inhibited in a dose-dependent manner the IL-4-induced proliferation of lipopolysaccharide-stimulated murine splenic B-cells, of the murine T cell line CTLL-2, and of the murine pre-B-cell line BA/F3. QY also inhibited the IL-4-stimulated up-regulation of CD23 expression by lipopolysaccharide-stimulated murine splenic B-cells and abolished tyrosine phosphorylation of the transcription factor Stat6 and the tyrosine kinase Jak3 in IL-4-stimulated BA/F3 cells. Selective inhibition of IL-4 may be beneficial in T-helper cell type 2-dominated diseases, like type I hypersensitivity reactions or helminthic infections. The QY mutant could be an attractive tool to study in vivo the therapeutic potential of IL-4 antagonists in mouse systems.