RESUMO
CD23 is atypically highly expressed in various chronic diseases, including B-CLL, lupus erythematodes and rheumatoid arthritis. Its expression can be further enhanced by interleukin 4 (IL-4). We have shown before that in B-CLL cells nuclear factor(s) of activated T cells (NF-ATs) show permanent nuclear localization and therefore constitutive transcriptional activity. Here we identify CD23b promoter as a novel target for NF-AT factors in B-CLL cells. The CD23b promoter contains two NF-AT binding sites to which NF-ATp and NF-ATc factors bind with high affinity. Mutations introduced into these sites abolished NF-AT binding and impaired the promoter activity, as did cyclosporin A (CsA), an inhibitor of nuclear transport of NF-ATs. Furthermore, we show that IL-4-induced transcription factor STAT6 cooperates with NF-ATs in the induction of the CD23b promoter activity. These results show that the CD23b promoter is a target for NF-AT factors and suggest that the cooperation between NF-AT and STAT factors might be one of the molecular mechanisms responsible for high-level expression of CD23 on the surface of B-CLL cells.
Assuntos
Proteínas de Ligação a DNA/farmacologia , Leucemia de Células B/metabolismo , Proteínas Nucleares , Regiões Promotoras Genéticas , Receptores de IgE/genética , Fatores de Transcrição/farmacologia , Sequência de Bases , Sítios de Ligação , DNA/química , Proteínas de Ligação a DNA/genética , Ensaio de Desvio de Mobilidade Eletroforética , Regulação Neoplásica da Expressão Gênica , Marcação de Genes , Ionomicina , Leucemia de Células B/imunologia , Dados de Sequência Molecular , Fatores de Transcrição NFATC , Receptores de IgE/biossíntese , Fator de Transcrição STAT6 , Acetato de Tetradecanoilforbol , Transativadores/genética , Transativadores/farmacologia , Fatores de Transcrição/genética , Transfecção , Células Tumorais CultivadasRESUMO
CD23 is constitutively and atypically expressed on malignant B-cells in patients with chronic lymphocytic leukemia. It exists in two isoforms that differ only in a short amino acid sequence at the N-terminus. The CD23a isoform exhibits an endocytosis signal, that renders it more efficient in antigen uptake than CD23b. Therefore, we analyzed the regulation of CD23 isoforms and tested the ability to stimulate T-cell clones by targeting antigen to CD23 on CLL B-cells. Investigation of several stimulators to promote CD23a expression on CLL versus normal B-cells confirmed a different CD23 regulation in B-CLL. We did not find any evidence for a differential regulation of the two CD23 isoforms in B-CLL. However, CD23a is always predominantly expressed with a constant ratio of CD23a:CD23b. We show that antigen targeted to CD23 on CLL B-cells is very efficiently presented. Therefore, CD23 is likely to provide a suitable target for receptor-mediated antigen presentation in B-CLL which can be used to activate a T-cell response.
Assuntos
Linfócitos B/metabolismo , Regulação Leucêmica da Expressão Gênica , Leucemia Linfocítica Crônica de Células B/genética , Proteínas de Neoplasias/biossíntese , Células-Tronco Neoplásicas/metabolismo , Isoformas de Proteínas/biossíntese , Receptores de IgE/biossíntese , Apresentação de Antígeno , Antígenos/metabolismo , Linfócitos B/efeitos dos fármacos , Endocitose , Regulação Leucêmica da Expressão Gênica/efeitos dos fármacos , Humanos , Imunoterapia , Interleucina-4/farmacologia , Leucemia Linfocítica Crônica de Células B/patologia , Ativação Linfocitária , Proteínas de Neoplasias/genética , Células-Tronco Neoplásicas/efeitos dos fármacos , Isoformas de Proteínas/genética , Receptores de IgE/genética , Linfócitos T/imunologia , Células Tumorais Cultivadas/imunologiaRESUMO
An introduction to the concept and practical implementation of a project entitled "Care in families for young people with mental disorders" is presented. In a project five adolescents were placed in fostering families. Continuous care is provided by a professional family care team and the treatment as out-patients at the Department of Child und Adolescent Psychiatry and Psychotherapy, in which they were previously treated, is continued.
Assuntos
Cuidados no Lar de Adoção/organização & administração , Transtornos Mentais/terapia , Psicoterapia/métodos , Adolescente , Terapia Familiar/métodos , Feminino , Cuidados no Lar de Adoção/economia , Alemanha , Humanos , Masculino , Transtornos Mentais/economia , Pacientes Ambulatoriais , Relações Pais-Filho , Equipe de Assistência ao Paciente/organização & administração , Projetos Piloto , Psicoterapia/economiaRESUMO
Human CD23 (the low affinity IgE receptor) is a B cell differentiation marker involved in inflammatory responses. Two isoforms (CD23a and CD23b) are known, which differ only in their cytoplasmic domain. Whereas CD23b expression is specifically induced by IL-4 on B cells and cells of the myeloid lineage, CD23a expression is restricted to B cells. Each isoform is regulated by its own promoter. Pax-5 is a B-cell-restricted transcription factor with an essential role in early and late B cell development. Analyses of the CD23a promoter revealed a Pax-5-binding site, which can compete a high affinity Pax-5-binding site or directly bind Pax-5 protein in electrophoretic mobility shift assays. Introducing mutations into this site abrogates the binding. Expression of Pax-5 in 293 cells resulted in a seven- to tenfold activation of a CD23a core promoter construct. Most importantly, ectopic expression of Pax-5 in the monocytic cell line U-937, which regularly expresses only the CD23b isoform, led to CD23a expression after stimulation with IL-4 and PMA. Our results suggest that Pax-5 is a key regulator of the B-cell-restricted expression of the CD23a isoform.