We demonstrate that purified HTLV-I Tax1 protein can be taken up by 70Z/3 lymphoid cells and localized in both the nuclear and cytoplasmic compartments. Introduction of the Tax1 protein into the growth medium of 70Z/3 cells resulted in the rapid and transient induction of NF-κB binding activity in the nuclear fraction. Tax1 activation of NF-κB was not sensitive to either staurosporin or prolonged stimulation with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate, suggesting that Tax1-dependent NF-κB activation did not require the protein kinase C pathway. Purified Tax1 did not directly increase NF-κB binding activity in 70Z/3 cytoplasmic extracts, suggesting that NF-κB induction may require cellular factors. Western blot and competitive radioimmunoassays demonstrated that Tax1 protein was present in the tissue culture media of HTLV-I-transformed cell lines. These results show that extracellular Tax1 may regulate cellular gene expression in noninfected cells.
|Original language||English (US)|
|Number of pages||10|
|State||Published - Dec 1 1990|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)