Enhanced nuclear factor-kappa B activation induced by tumour necrosis factor-alpha in stably tat-transfected cells is associated with the presence of cell-surface-bound Tat protein.
AIDS
; 10(5): 455-61, 1996 May.
Article
en En
| MEDLINE
| ID: mdl-8724035
ABSTRACT
OBJECTIVE:
An enhanced nuclear factor (NF)-kappa B activation in response to tumour necrosis factor (TNF)-alpha has been observed in stably tat-transfected cells. Recent experimental evidence suggests that Tat may autocrinously influence both cellular physiology and HIV-1 long terminal repeat-directed gene expression in Tat-producing cells. Therefore, the possible association of a Tat autocrinous loop with the enhanced NF-kappa B-binding activity induced by TNF-alpha in Tat-producing cells was studied by anti-Tat antibody blocking experiments. DESIGN ANDMETHODS:
Permanently tat-transfected Jurkat cells, maintained either in the presence or absence of anti-Tat antibody, were studied for the presence of TNF-alpha-induced NF-kappa B-binding activity (quantified by electrophoretic mobility shift assays) and the presence of cell-surface-bound Tat (determined by flow cytometry and confocal microscopy of anti-Tat immunofluorescence-stained cell preparations.RESULTS:
The enhanced production of TNF-alpha-induced NF-kappa B binding activity exhibited by tat-transfected Jurkat cells was completely abolished in cell cultures maintained in the presence of anti-Tat antibody, thus indicating that the increased TNF-alpha-induced NF-kappa B binding activity observed in Jurkat-tat cells was dependent on the presence of Tat protein in an antibody-accessible location. In accordance with these findings, immunofluorescence-stained preparations of unfixed tat-transfected Jurkat cells showed the presence of cell-surface-bound Tat protein which was completely absent in cells incubated in the presence of anti-Tat antibodies.CONCLUSIONS:
This study demonstrates that the enhanced NF-kappa B activation exhibited by stably tat-transfected cells in response to TNF-alpha, is associated with cell surface interaction of extracellularly released Tat protein. These data add further evidence to the possible relevance of a Tat autocrinous loop in the physiology of Tat-producing cells and suggest that in HIV-1-infected cells Tat is likely to behave as a bifunctional molecule which not only acts from within facilitating NF-kappa B recruitment in the viral transcription complex, but may also act from without increasing the availability of activated NF-kappa B.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Linfocitos
/
Productos del Gen tat
/
Membrana Celular
/
FN-kappa B
/
VIH-1
/
Factor de Necrosis Tumoral alfa
Tipo de estudio:
Risk_factors_studies
Límite:
Humans
Idioma:
En
Revista:
AIDS
Asunto de la revista:
SINDROME DA IMUNODEFICIENCIA ADQUIRIDA (AIDS)
Año:
1996
Tipo del documento:
Article
País de afiliación:
Italia