Expression of Bcl-2, Bcl-x, and Bax after T cell activation and IL-2 withdrawal.
J Immunol
; 155(5): 2311-7, 1995 Sep 01.
Article
em En
| MEDLINE
| ID: mdl-7650367
ABSTRACT
Bcl-2, bcl-x, and bax genes code for proteins that affect the susceptibility of cells to apoptosis. In general, the expression of bcl-2 or bcl-x inhibits apoptosis while bax promotes apoptosis. We examined the levels of these proteins by immunoblotting in resting and activated T cells and in thymocytes. Bcl-2 and Bax proteins vary coordinately, but Bcl-x varies independently Bcl-2 and Bax are higher in splenic T cells than in thymocytes, and their levels increase even more after T cell activation. In contrast, Bcl-x is almost undetectable in splenic T cells but is manyfold greater in thymocytes and in activated splenic T cells. When CTLL-2 cells or activated T cells are starved of IL (IL-2), the level of Bcl-x but not Bcl-2 protein drops before the onset of apoptosis. Stable transfection of either bcl-2 or bcl-x expression plasmids promotes the survival of CTLL-2 cells in the setting of IL-2 withdrawal. Over 70 to 90% of the transfected cells remain viable at 48 h after IL-2 withdrawal when all of the control transfected cells are apoptotic. These findings suggest that a decrease in Bcl-x protein levels precedes apoptosis after IL-2 withdrawal in T cells and that transfected bcl-2 promotes survival after IL-2 withdrawal by functionally masking this drop in Bcl-x.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Linfócitos T
/
Proteínas Proto-Oncogênicas
/
Interleucina-2
Limite:
Animals
Idioma:
En
Revista:
J Immunol
Ano de publicação:
1995
Tipo de documento:
Article
País de afiliação:
Estados Unidos