title: Synaptotagmin 3 deficiency in T cells impairs recycling of the chemokine receptor CXCR4 and thereby inhibits CXCL12 chemokine-induced migration.
abstract: Synaptotagmins regulate vesicle trafficking and fusion of vesicles with membranes - processes that have been implicated in cell migration. We therefore hypothesized that synaptotagmins play a role in T-cell migration. Amongst synaptotagmins 1-11, we found synaptotagmin 3 (SYT3) to be the only one that is expressed in T cells. CXCR4-triggered migration was inhibited by antisense synaptotagmin 3 mRNA and by the isolated C2B domain, known to impair oligomerization of all synaptotagmins, but not by a C2B mutant that binds Ca(2+) but does not block oligomerization. The C2B domain also blocked CXCR4-triggered actin polymerization and invasion. However, CXCR4-dependent adhesion in flow was not affected. Surprisingly, we found that little or no SYT3 is present near the plasma membrane but that it is mainly localized in multivesicular bodies, which also contained much of the CXCR4. Impaired SYT3 function blocked CXCR4 recycling and thus led to reduced surface levels of CXCR4. Migration was restored by overexpression of CXCR4. We conclude that STT3 is essential for CXCR4 recycling in T cells and thereby for the maintenance of high CXCR4 surface levels required for migration.
authors.affiliation: Division of Cell Biology, The Netherlands Cancer Institute, 121 Plesmanlaan, 1066CX Amsterdam, The Netherlands.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Masztalerz
authors.forename: Ingrid S
authors.initials: IS
authors.lastname: Zeelenberg
authors.forename: Yvonne M
authors.initials: YM
authors.lastname: Wijnands
authors.forename: Rosalie
authors.initials: R
authors.lastname: de Bruijn
authors.forename: Angelika M
authors.initials: AM
authors.lastname: Drager
authors.forename: Hans
authors.initials: H
authors.lastname: Janssen
authors.forename: Ed
authors.initials: E
authors.lastname: Roos
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000187:drug effects*; D002478:Cells, Cultured; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000494:pharmacology*; D002633:Chemotaxis; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000378:metabolism; D006825:Hybridomas / Q000166:cytology; D051379:Mice; D008819:Mice, Nude; D019718:Receptors, CXCR4 / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D050857:Synaptotagmins / Q000172:deficiency* / Q000235:genetics; D013601:T-Lymphocytes / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D054377:Chemokine CXCL12; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D019718:Receptors, CXCR4; D011993:Recombinant Fusion Proteins; D050857:Synaptotagmins; D049452:Green Fluorescent Proteins; D005982:Glutathione Transferase