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Differentiation of naive CD4 T cells into Th2 cells requires protein expression of GATA3. Interleukin-4 induces STAT6 activation and subsequent GATA3 transcription. Little is known, however, on how T cell receptor-mediated signaling regulates GATA3 and Th2 cell differentiation. Here we demonstrated that T cell receptor-mediated activation of the Ras-ERK MAPK cascade stabilizes GATA3 protein in developing Th2 cells through the inhibition of the ubiquitin-proteasome pathway. Mdm2 was associated with GATA3 and induced ubiquitination on GATA3, suggesting its role as a ubiquitin-protein isopeptide ligase for GATA3 ubiquitination. Thus, the Ras-ERK MAPK cascade controls GATA3 protein stability by a post-transcriptional mechanism and facilitates GATA3-mediated chromatin remodeling at Th2 cytokine gene loci leading to successful Th2 cell differentiation. [ABSTRACT FROM AUTHOR]

Interleukin 5 (IL-5) plays a unique role in allergic inflammatory responses, and the understanding of molecular mechanisms underlying the generation of IL-5producing cells is crucial for the regulation of allergic disorders. Differentiation of naive CD4 T cells into type-2 helper (Th2) cells is accompanied by chromatin remodeling including hyperacetylation of histones H3 and H4 in the nucleosomes associated with the IL-4, IL-13, and IL-5 genes. Histone hyperacetylation of the IL-5 gene displayed a delayed kinetics compared with that of the IL-4 and IL-13 genes, suggesting a distinct remodeling mechanism for the IL-5-gene locus. Here we studied the role of CD28 costimulation in the generation of IL-5-producing cells and the histone hyperacetylation of the IL-5 gene locus. CD28-costimulation selectively enhanced histone hyperacetylation of the IL-5 gene locus that appeared to be mediated through NF-κB activation and subsequent up-regulation of GATA3. The CD28 costimulation-sensitive histone hyperacetylation spanned almost the entire intergenic region between the IL-5 and RAD50 accompanied with intergenic transcript. Thus, this is the first demonstration that CD28 costimulation controls a chromatin-remodeling process during Th2 cell differentiation. [ABSTRACT FROM AUTHOR]

Studies have demonstrated that active-specific immunotherapy has potential for controlling melanoma progression. We developed a polyvalent melanoma gene vaccine using a plasmid vector to deliver the immunogenic human melanoma-associated antigens (MAAs) gp100 and TRP-2. The MAA-containing plasmids were delivered individually in vivo using the hemagglutinating virus Japan (HVJ)–anionic liposome delivery system. C57BL/6 mice were immunized weekly by intramuscular (i.m.) injection or intranasal (i.n.) inoculation for 3 weeks. Although both i.m. and i.n. immunization induced Th1 (T helper) and Th2 cell responses to gp100 and TRP2, the i.m. route induced a better Th1 response. MAA-specific IgG2a, IgG1, and delayed-type hypersensitivity (DTH) responses were induced against both MAAs by i.m. immunization. We assessed the vaccine for its prophylactic and therapeutic effect against the murine B16 F10 melanoma. Animals vaccinated and subsequently challenged with a lethal dose of B16 cells were significantly (P<0.01) protected against tumor progression and had significantly (P<0.01) enhanced survival compared with treatment using control plasmid. We also developed a therapeutic model in which mice were given B16 cells and subsequently immunized with the vaccine or treated with control plasmid. In animals treated with the vaccine, tumor growth was significantly (P<0.01) controlled, and survival was prolonged compared with controls. These studies demonstrate that the polyvalent DNA vaccine induces an effective systemic Th response. [Copyright &y& Elsevier]