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J. Virol., 11 1997, 8522-8530, Vol 71, No. 11
H Valentin, I Lemasson, S Hamaia, H Casse, S Konig, C Devaux and L Gazzolo
Recruitment and extravasation of T cells through the blood-brain barrier
are favored by adhesion molecule-mediated interactions of circulating T
cells with endothelial cells. Since a common pathological finding in human
T-cell leukemia virus type 1 (HTLV-1)-associated diseases is the
infiltration of HTLV-1-infected T lymphocytes into various organs, we have
looked for the profile of adhesion molecules expressed by
HTLV-1-transformed T cells. Flow cytometry analysis indicated that these
cells were expressing high levels of vascular cell adhesion molecule 1
(VCAM-1 [CD106]), a 110-kDa member of the immunoglobulin gene superfamily,
first identified on endothelial cells stimulated with inflammatory
cytokines. This adhesion molecule was also expressed by T cells obtained
from one patient with HTLV-1-associated myelopathy/tropical spastic
paraparesis but not by activated T cells isolated from one normal blood
donor. The role of the viral trans- activator Tax protein in the induction
of VCAM-1 was first indicated by the detection of this adhesion molecule on
Jurkat T-cell clones stably expressing the tax gene. The effect of Tax on
VCAM-1 gene transcription was next confirmed in JPX-9 cells, a subclone of
Jurkat cells, carrying the tax sequences under the control of an inducible
promoter. Furthermore, deletion and mutation analyses of the VCAM-1
promoter performed with chloramphenicol acetyltransferase constructs
revealed that Tax was trans activating the VCAM-1 promoter via two
NF-kappaB sites present at bp -72 and -57 in the VCAM-1 gene promoter, with
both of them being required for the Tax-induced expression of this adhesion
molecule. Finally, gel mobility shift assays demonstrated the nuclear
translocation of proteins specifically bound to these two NF-kappaB motifs,
confirming that VCAM-1 was induced on Tax-expressing cells in a
kappaB-dependent manner. Collectively, these results therefore suggest that
the exclusive Tax-induced expression of VCAM-1 on T cells may represent a
pivotal event in the progression of HTLV-1-associated diseases.
Copyright © 1997, American Society for Microbiology
Transcriptional activation of the vascular cell adhesion molecule-1 gene in T lymphocytes expressing human T-cell leukemia virus type 1 Tax protein
Immuno-Virologie Moleculaire et Cellulaire (UMR 5537), CNRS-UCB Lyon I, Faculte de Medecine Lyon-RTH, Laennec, France.
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