title: Syndecan-2 can promote clearance of T-cell receptor/CD3 from the cell surface.
abstract: T cells express the heparan sulphate proteoglycans syndecan-2 and syndecan-4. Syndecan-4 plays a T-cell inhibitory role; however, the function of syndecan-2 is unknown. In an attempt to examine this function, syndecan-2 was expressed constitutively in Jurkat T cells. Interestingly, the expression of syndecan-2 decreased the surface levels of T-cell receptor (TCR)/CD3 complex, concomitant with intracellular retention of CD3ε and partial degradation of the TCR-ζ chain. Immunofluorescence microscopy revealed that intracellular CD3ε co-located with Rab-4 endosomes. However, the intracellular pool of CD3ε did not recycle to the cell surface. The lower TCR/CD3 surface levels caused by syndecan-2 led to reduced TCR/CD3 responsiveness. We show that the cytosolic PDZ-binding domain of syndecan-2 is not necessary to elicit TCR/CD3 down-regulation. These results identify a previously unrecognized means of controlling surface TCR/CD3 expression by syndecan-2.
authors.affiliation: Departament de Biologia Cellular, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Rovira-Clavé
authors.forename: Maria
authors.initials: M
authors.lastname: Angulo-Ibáñez
authors.forename: Oriol
authors.initials: O
authors.lastname: Noguer
authors.forename: Enric
authors.initials: E
authors.lastname: Espel
authors.forename: Manuel
authors.initials: M
authors.lastname: Reina
mesh_terms: D017252:CD3 Complex / Q000276:immunology*; D015536:Down-Regulation; D006801:Humans; D019169:Jurkat Cells; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D053669:Syndecan-2 / Q000276:immunology*
chemical_list: D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D053669:Syndecan-2