Signaling through the tetraspanin CD82 triggers its association with the cytoskeleton leading to sustained morphological changes and T cell activation

Abstract

In this report, we provide new evidence of a crosstalk between T cell activation and adhesion processes through a functional cytokeleton. We show that CD82 signaling induces long-lasting adhesion, spreading and development of membrane extensions, involving actin polymerization. Addition of various co-stimuli (phorbol 12-myristate 13-acetate or monoclonal antibodies to CD3 or CD2) increases the CD82-induced morphological alterations and, reciprocally, CD82 engagement synergizes with these stimuli to induce T cell activation as indicated by both primary tyrosine phosphorylation and IL-2 production. Different kinases are involved in both processes. CD82 co-signaling involves src kinases including p56 Ick. On the other hand, the CD82-induced alterations of cell morphology are negatively regulated by cAMP-dependent kinases independently of activation of src kinases. Simultaneously with cytoskeletal rearrangements, we observed an inducible association of CD82 with the cytoskeletal matrix. In addition, the potentiating and stabilizing effects induced by CD82 cross-linking on tyrosine phosphorylation were abolished by cytoskeleton-disrupting agents. These results suggest that the actin polymerization triggered by CD82, through its ability to associate with the cytoskeletal matrix, is the primary step involved in the CD82 induced co-stimulatory activity. Our data provide further evidence for a direct role of the actin cytoskeleton as a major component for sustained signal transduction in T cells and suggest that tetraspanins could be "membrane organizers" connecting both surface and intracellular molecules.

Tetraspanins Regulate ADAM10-Mediated Cleavage of TNF-α and Epidermal Growth Factor

“…Tetraspanins have been shown to be coupled to diverse signal transduction pathways, including PKC, tyrosine kinases, and the MAPK pathways (44,(63)(64)(65)(66)(67). As expected, the PKC inhibitor bisindolylmaleimide I blocked the release of TNF-␣ induced by the PKC activator TPA.…”

“…The effect of anti-tetraspanin mAbs on TNF-␣ release is rapid and does not depend on extracellular signaling. Anti-tetraspanins mAbs induce in minutes the phosphorylation of proteins on tyrosine residues in certain B or T lymphoid cell lines (44,63,64). However, we did not detect any induction of tyrosine phosphorylation in the Raji cell line incubated with anti-tetraspanin mAbs (data not shown), and the tyrosine kinase inhibitor herbimycin A did not inhibit the increased release of TNF-␣ produced by anti-tetraspanin mAbs, suggesting that the effect does not rely on protein tyrosine phosphorylation.…”

Tetraspanin KAI1/CD82 suppresses invasion by inhibiting integrin-dependent crosstalk with c-Met receptor and Src kinases

“…In T cells, anti-CD82 antibodies were shown to activate p56lck, a member of Src kinase family; however, this was only observed in the context of costimulation of the T-cell receptor and was not observed upon cell adhesion to anti-CD82 antibodies (Lagaudriere-Gesbert et al, 1998). In CD82-transfected DU145 cells, anti-CD82 antibody enhanced Src kinase activity in cell-cell aggregates in suspension independently of integrins (Jee et al, 2003).…”

Complementary costimulation of human T-cell subpopulations by cluster of differentiation 28 (CD28) and CD81

“…However, additional members of the CD28 family, such as ICOS and several members of the TNF family, such as CD27 and CD137 (4-1BB) are well known T-cell costimulatory molecules (13,14). Less investigated is the costimulatory effect of the tetraspanin family of molecules, including CD9, CD53, CD63, CD81 and CD82 (15)(16)(17)(18)(19)(20)(21)(22)(23)(24). Interestingly, costimulation either by CD9 or by CD81 occurs in CD28-deficient T cells, suggesting either a different or a redundant activation pathway (18,19).…”

“…Most recently, ezrin silencing was shown to reduce cytoskeletal clustering and to modulate TCR signaling (51)(52)(53). The linkage of tetraspanins to the cytoskeleton is not limited to CD81; for example, CD82 was shown to act as a cytoskeletal-dependent costimulatory molecule, which was localized at the TCR engagement site (21).…”