RESUMO
Human T-cell leukemia virus type I (HTLV-I) is the etiologic agent for adult T-cell leukemia and the neurological disorder tropical spastic paraparesis/HTLV-I-associated myelopathy. CD4+ T lymphocytes, the primary hosts for HTLV-I, undergo a series of changes that lead to T-cell activation, immortalization, and transformation. To gain insight into the genetic differences between activated and HTLV-I-infected lymphocytes, we performed Affymetrix GeneChip analysis of activated and HTLV-I-infected cells. Using the Hu6800 GeneChip, we identified approximately 763 genes that had differentially regulated expression in at least three of five HTLV-I cell lines. Classification of these genes into functional groups including cellular receptors, kinases, phosphatases, cytokines, signal proteins, and transcription factors provides insight into genes and pathways that are differentially regulated during HTLV-I transformation.
Assuntos
Vírus Linfotrópico T Tipo 1 Humano/genética , Ativação Linfocitária/genética , Linfócitos T/fisiologia , Linfócitos T/virologia , Apoptose/genética , Proteínas de Ciclo Celular/biossíntese , Proteínas de Ciclo Celular/genética , Transformação Celular Viral/genética , Transformação Celular Viral/imunologia , Células Cultivadas , Citocinas/biossíntese , Citocinas/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Regulação Viral da Expressão Gênica , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , Humanos , Subunidade alfa de Receptor de Interleucina-2 , Células Jurkat/metabolismo , Células Jurkat/fisiologia , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Receptores de Interleucina/biossíntese , Receptores de Interleucina/genética , Linfócitos T/imunologia , Linfócitos T/metabolismo , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genética , Transcrição Gênica , TransfecçãoRESUMO
The p53 tumor suppressor protein plays a critical role in mediating cellular response to stress. Upon DNA damage, post-translational modifications stabilize and activate this nuclear phosphoprotein. To determine the effect of phosphorylation site mutants in the context of the whole p53 protein, we performed reporter assays in p53 and MDM2 knockout mouse embryonic fibroblasts transfected with full-length p53 constructs. We show that mutation of S37 causes a decrease in p53 transcriptional activity compared to wild-type p53. Our data further suggest that the dephosphorylation of p53 at S37 is a regulated event involving protein phosphatase 2A (PP2A). Coimmunoprecipitation and immunofluorescence microscopy studies demonstrate that PP2A and p53 associate with one another in vivo following gamma-irradiation. Consistent with these observations, phosphorylated S37 accumulates in cell extracts prepared from gamma-irradiated Molt-4 cells in the presence of okadaic acid. Furthermore, in vitro phosphatase assays show that PP2A dephosphorylates p53 at S37. These results suggest that dephosphorylation of p53 at S37 plays a role in the transcriptional regulation of the p53 protein in response to DNA damage.