Surface cytotoxic T lymphocyte-associated antigen 4 partitions within lipid rafts and relocates to the immunological synapse under conditions of inhibition of T cell activation

• Published in: The Journal of experimental medicine 2002-05, Vol.195 (10), p.1337-1347
• Main Authors: Darlington, Peter J, Baroja, Miren L, Chau, Thu A, Siu, Eric, Ling, Vincent, Carreno, Beatriz M, Madrenas, Joaquín
• Format: Article
• Language: English
• Subjects: Abatacept; Antigen-Presenting Cells - immunology; Antigens, CD; Antigens, Differentiation - genetics; Antigens, Differentiation - metabolism; CTLA-4 Antigen; Flow Cytometry; Glycosylphosphatidylinositols - metabolism; Humans; Immunoconjugates; Interleukin-2 - antagonists & inhibitors; Jurkat Cells; Lymphocyte Activation; Membrane Microdomains - chemistry; Membrane Microdomains - metabolism; Microscopy, Confocal; Molecular Sequence Data; Protein Transport; Receptors, Antigen, T-Cell - immunology; Signal Transduction; T-Lymphocytes - cytology; T-Lymphocytes - immunology; T-Lymphocytes - metabolism
• ISSN: 0022-1007; 1540-9538
• DOI: 10.1084/jem.20011868

T cell activation through the T cell receptor (TCR) involves partitioning of receptors into discrete membrane compartments known as lipid rafts, and the formation of an immunological synapse (IS) between the T cell and antigen-presenting cell (APC). Compartmentalization of negative regulators of T cell activation such as cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) is unknown. Recent crystal structures of B7-ligated CTLA-4 suggest that it may form lattices within the IS which could explain the mechanism of action of this molecule. Here, we show that after T cell stimulation, CTLA-4 coclusters with the TCR and the lipid raft ganglioside GM1 within the IS. Using subcellular fractionation, we show that most lipid raft-associated CTLA-4 is on the T cell surface. Such compartmentalization is dependent on the cytoplasmic tail of CTLA-4 and can be forced with a glycosylphosphatidylinositol-anchor in CTLA-4. The level of CTLA-4 within lipid rafts increases under conditions of APC-dependent TCR-CTLA-4 coligation and T cell inactivation. However, raft localization, although necessary for inhibition of T cell activation, is not sufficient for CTLA-4-mediated negative signaling. These data demonstrate that CTLA-4 within lipid rafts migrates to the IS where it can potentially form lattice structures and inhibit T cell activation.