Constitutive clathrin-mediated endocytosis of CTLA-4 persists during T cell activation.
J Biol Chem
; 287(12): 9429-40, 2012 Mar 16.
Article
em En
| MEDLINE
| ID: mdl-22262842
ABSTRACT
CTLA-4 is one of the most important negative regulators of the T cell immune response. However, the subcellular distribution of CTLA-4 is unusual for a receptor that interacts with cell surface transmembrane ligands in that CTLA-4 is rapidly internalized from the plasma membrane. It has been proposed that T cell activation can lead to stabilization of CTLA-4 expression at the cell surface. Here we have analyzed in detail the internalization, recycling, and degradation of CTLA-4. We demonstrate that CTLA-4 is rapidly internalized from the plasma membrane in a clathrin- and dynamin-dependent manner driven by the well characterized YVKM trafficking motif. Furthermore, we show that once internalized, CTLA-4 co-localizes with markers of recycling endosomes and is recycled to the plasma membrane. Although we observed limited co-localization of CTLA-4 with lysosomal markers, CTLA-4 was nonetheless degraded in a manner inhibited by lysosomal blockade. T cell activation stimulated mobilization of CTLA-4, as judged by an increase in cell surface expression; however, this pool of CTLA-4 continued to endocytose and was not stably retained at the cell surface. These data support a model of trafficking whereby CTLA-4 is constitutively internalized in a ligand-independent manner undergoing both recycling and degradation. Stimulation of T cells increases CTLA-4 turnover at the plasma membrane; however, CTLA-4 endocytosis continues and is not stabilized during activation of human T cells. These findings emphasize the importance of clathrin-mediated endocytosis in regulating CTLA-4 trafficking throughout T cell activation.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Ativação Linfocitária
/
Linfócitos T CD4-Positivos
/
Endocitose
/
Antígeno CTLA-4
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article