Previous Article | Next Article ![]()
J. Virol., Apr 1996, 2525-2532, Vol 70, No. 4
PF Lindholm, M Tamami, J Makowski and JN Brady
Human T-cell lymphotropic virus type 1 Tax1 induces the activation and
nuclear localization of the cellular transcription factor, NF-kappa B.
Treatment of cells with calphostin C, a protein kinase C (PKC) inhibitor,
blocked induction of NF-kappa B DNA binding activity in human T-cell
lymphotropic virus type 1-transformed C81 cells and Tax1- stimulated murine
pre-B cells, suggesting that PKC was an important intermediate in the
NF-kappa B induction pathway. We further demonstrate that Tax1 associates
with, and activates, PKC. PKC was coimmunoprecipitated with anti- Tax1 sera
from Tax1-expressing MT4 extracts and Jurkat extracts in the presence of
exogenous Tax1 protein. In addition, the glutathione-S-transferase-Tax1
protein bound specifically to the alpha, delta, and eta PKC isoenzymes
synthesized in rabbit reticulocyte lysates. The addition of Tax1 to in
vitro kinase reaction mixtures leads to the phosphorylation of Tax1 and an
18-fold increase in the autophosphorylation of PKC. Transfection of Jurkat
cells with wild-type Tax1 stimulated membrane translocation of PKC. In
contrast, Tax1 mutant M22, which fails to stimulate NF-kappa B- dependent
transcription, failed to stimulate membrane translocation of PKC. Tax1 did
not directly increase PKC phosphorylation of I kappa B alpha. Our results
are consistent with a model in which Tax1 interacts with PKC and stimulates
membrane translocation and triggering of the PKC pathway. Subsequent steps
in the PKC cascade likely stimulate phosphorylation of I kappa B alpha.
Copyright © 1996, American Society for Microbiology
Human T-cell lymphotropic virus type 1 Tax1 activation of NF-kappa B: involvement of the protein kinase C pathway
Laboratory of Molecular Virology, National Cancer Institute, Bethesda, Maryland 20892-5005, USA.
This article has been cited by other articles:
| J. Bacteriol. | Mol. Cell. Biol. | Microbiol. Mol. Biol. Rev. |
|---|
| Clin. Vaccine Immunol. | ALL ASM JOURNALS |
|---|