c-fos promoter trans-activation by the tax1 protein of human T-cell leukemia virus type I.

AUTOR(ES)

Fujii, M

RESUMO

To understand the mechanisms of oncogenesis by human T-cell leukemia virus type I, we have investigated the ability of the tax1, protein to modulate transcription of protooncogenes. By using a transient cotransfection assay, we report that the protooncogene fos promoter is transactivated by tax1 in a variety of cell types. Two regions containing upstream sequences between positions -362/-324 and -323/-276 of the c-fos promoter responded to this activation and also conferred tax1 responsiveness to the heterologous herpesvirus thymidine kinase promoter. These two sequences include elements mediating the induction by v-sis-conditioned medium and serum, phorbol ester, or epidermal growth factor, respectively. Furthermore, expression of the endogenous c-fos gene was activated by tax1 in human T-cell leukemia virus type I-infected cell lines. In contrast, no trans-activation of the c-myc or c-Ha-ras promoter was observed.

Documentos Relacionados

• trans activation of the tumor necrosis factor alpha promoter by the human T-cell leukemia virus type I Tax1 protein.
• Transactivation of the proenkephalin gene promoter by the Tax1 protein of human T-cell lymphotropic virus type I.
• Activation of endogenous c-fos proto-oncogene expression by human T-cell leukemia virus type I-encoded p40tax protein in the human T-cell line, Jurkat.
• trans-activation of the simian virus 40 enhancer by a pX product of human T-cell leukemia virus type I.
• E1A-dependent trans-activation of the c-fos promoter requires the TATAA sequence.