RESUMEN
The impact of CD28 ligation upon CD4+ and CD8+ T lymphocyte proliferation and cytokine production was assessed. Although costimulation increased the proliferative response of both T cell subsets, cytokine production was most markedly increased in the CD4+ subset, as evidenced by a 40-fold increase in interleukin-2 (IL-2), a 14-fold increase in interleukin-3 (IL-3) and 5-fold increases in interferon gamma and GM-colony-stimulating factor (CSF) production. The CD8+ T cell response to CD28 ligation was less marked, maxima being a 5-fold increase in IL-2 production and 2-fold increases in IL-3 and GM-CSF production. Resolution of CD4+ and CD8+ T cells into their CD44lo (naïve) and CD44hi (memory/effector) subsets revealed that naive CD4+ T cells were the most CD28-responsive subsets. CD28-mediated costimulation promotes distinct differentiation programs in CD4+ versus CD8+ T cells.
Asunto(s)
Antígenos CD28/inmunología , Linfocitos T CD4-Positivos/metabolismo , Linfocitos T CD8-positivos/metabolismo , Citocinas/metabolismo , Animales , Linfocitos T CD4-Positivos/citología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/citología , Linfocitos T CD8-positivos/inmunología , División Celular/inmunología , Citocinas/genética , Receptores de Hialuranos/inmunología , Receptores de Hialuranos/metabolismo , Masculino , Ratones , Ratones Endogámicos BALB C , ARN Mensajero/metabolismo , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Factores de TiempoRESUMEN
Basal transcription of the HIV-1 genome is controlled by a variety of ubiquitous and inducible regulatory factors, some with the ability to associate with the viral DNA sequences within the promoter spanning the long terminal repeat (LTR). In this report we demonstrate that activation of the HIV-1 promoter through the inducible DNA binding NF-kappaB transcription factors can be affected by cdk9 in human astrocytic cells. Our results show that ectopic expression of cdk9, but not its mutant variant which lacks the domain responsible for its kinase activity, augments transcription of the LTR. Moreover, we demonstrate that induction of the NF-kappaB pathway by PMA, or overexpression of its subunits including p50/p65 have a negative effect on the ability of cdk9 to stimulate viral gene transcription in these cells. Results from band-shift experiments demonstrated significant suppression of p50/p65 association to its DNA target motif by cdk9. Further, data from GST pull-down and combined immunoprecipitation/Western blot analysis of the protein extracts from cells expressing cdk9, p50 and p65 have revealed the interaction of cdk9 with both p50 and p65 in the absence of DNA containing the kappaB motif. All of these observations led us to conclude that the interaction of cdk9 with the NF-kappaB factors can determine the ability of NF-kappaB to modulate HIV-1 gene transcription.