Tax oncoprotein trans-represses endogenous B-myb promoter activity in human T cells

C. Nicot, R. Opavsky, R. Mahieux, J. M. Johnson, J. N. Brady, L. Wolff, G. Franchini

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Abstract

The B-myb gene was identified on the basis of its homology with the protooncogene c-myb, homolog of the avian myeloblastosis virus (AMV) and avian leukemia virus (E26) transforming genes. Several studies using antisense constructs or antisense oligonucleotides as well as overexpression experiments suggest that B-Myb plays an important role in the transition from G1 to S phase of the cell cycle and that B-Myb expression is cell cycle regulated. We have previously demonstrated that the human T cell lymphotropic virus type 1 (HTLV-1) trans-activator Tax is able to repress transcription from c, myb promoter reporter constructs as well as from the endogenous c-myb promoter in human T cells and that this effect is mediated through inhibition of the c-Myb trans-activating functions. Here we report that both HTLV-1 as well as HTLV-2 Tax proteins inhibit c-Myb trans-activation in mouse embryo fibroblasts (MEFs). In addition to c-Myb, B-Myb expression is also markedly downregulated in HTLV-1-transformed cells at both RNA and protein levels. Furthermore, by using a Jurkat T cell line stably transfected with a tax gene driven by a cadmium-inducible promoter (JPX9), we were able to demonstrate that Tax directly represses the endogenous B-myb promoter in T cells. Because c-Myb and B-Myb have been involved in cell cycle progression, our results Suggest that Tax, by repressing both c-Myb and B-Myb endogenous promoters, may bypass their requirement for cell cycle progression in HTLV-1-transformed T cells.

Original languageEnglish (US)
Pages (from-to)1629-1632
Number of pages4
JournalAIDS Research and Human Retroviruses
Volume16
Issue number16
DOIs
Publication statusPublished - Nov 1 2000

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ASJC Scopus subject areas

  • Immunology
  • Virology
  • Infectious Diseases

Cite this

Nicot, C., Opavsky, R., Mahieux, R., Johnson, J. M., Brady, J. N., Wolff, L., & Franchini, G. (2000). Tax oncoprotein trans-represses endogenous B-myb promoter activity in human T cells. AIDS Research and Human Retroviruses, 16(16), 1629-1632. https://doi.org/10.1089/08892220050193065