SYK regulates B-cell migration by phosphorylation of the F-actin interacting protein SWAP-70.
B-cell migration into and within lymphoid tissues is not only central to the humoral immune response but also for the development of malignancies and autoimmunity. We previously demonstrated that SWAP-70, an F-actin-binding, Rho GTPase-interacting protein strongly expressed in activated B cells, is necessary for normal B-cell migration in vivo. SWAP-70 regulates integrin-mediated adhesion and cell attachment. Here we show that upon B-cell activation, SWAP-70 is extensively posttranslationally modified and becomes tyrosine phosphorylated by SYK at position 517. This phosphorylation inhibits binding of SWAP-70 to F-actin. Phospho-site mutants of SWAP-70 disrupt B-cell polarization in a dominant-negative fashion in vitro and impair migration in vivo. After CXCL12 stimulation of B cells SYK becomes activated and SWAP-70 is phosphorylated in a SYK-dependent manner. Use of the highly specific SYK inhibitor BAY61-3606 showed SYK activity is necessary for normal chemotaxis and B-cell polarization in vitro and for entry of B cells into lymph nodes in vivo. These findings demonstrate a novel requirement for SYK in migration and polarization of naive recirculating B cells and show that SWAP-70 is an important target of SYK in this pathway.
Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Dresden University of Technology, Fiedlerstrasse 42, Dresden, Germany. 6305glen.pearce@mailbox.tu-dresden.de
Glen
G
Pearce
Tatsiana
T
Audzevich
Rolf
R
Jessberger
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D015153:Blotting, Western; D002465:Cell Movement; D004268:DNA-Binding Proteins / Q000502:physiology*; D005434:Flow Cytometry; D020662:Guanine Nucleotide Exchange Factors / Q000502:physiology*; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D015778:Minor Histocompatibility Antigens; D009687:Nuclear Proteins / Q000502:physiology*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000072377:Syk Kinase; D014443:Tyrosine / Q000378:metabolism*
D000199:Actins; D004268:DNA-Binding Proteins; D020662:Guanine Nucleotide Exchange Factors; D047908:Intracellular Signaling Peptides and Proteins; D015778:Minor Histocompatibility Antigens; D009687:Nuclear Proteins; C113365:Swap70 protein, mouse; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase; C000606897:Syk protein, mouse