Chemotaxis, a process leading to movement of cells toward increasing concentrations of chemoattractants, is essential, among others, for recruitment of mast cells within target tissues where they play an important role in innate and adaptive immunity. Chemotaxis is driven by chemoattractants, produced by various cell types, as well as by intrinsic cellular regulators, which are poorly understood. In this study we prepared a new mAb specific for the tetraspanin CD9. Binding of the antibody to bone marrow-derived mast cells triggered activation events that included cell degranulation, Ca(2+) response, dephosphorylation of ezrin/radixin/moesin (ERM) family proteins, and potent tyrosine phosphorylation of the non-T cell activation linker (NTAL) but only weak phosphorylation of the linker for activation of T cells (LAT). Phosphorylation of the NTAL was observed with whole antibody but not with its F(ab)(2) or Fab fragments. This indicated involvement of the Fcγ receptors. As documented by electron microscopy of isolated plasma membrane sheets, CD9 colocalized with the high-affinity IgE receptor (FcεRI) and NTAL but not with LAT. Further tests showed that both anti-CD9 antibody and its F(ab)(2) fragment inhibited mast cell chemotaxis toward antigen. Experiments with bone marrow-derived mast cells deficient in NTAL and/or LAT revealed different roles of these two adaptors in antigen-driven chemotaxis. The combined data indicate that chemotaxis toward antigen is controlled in mast cells by a cross-talk among FcεRI, tetraspanin CD9, transmembrane adaptor proteins NTAL and LAT, and cytoskeleton-regulatory proteins of the ERM family.

• MeSH
• Adaptor Proteins, Signal Transducing metabolism   MeSH
• Tetraspanin 29 physiology   MeSH
• Fusion Regulatory Protein 1, Light Chains metabolism   MeSH
• Antigens metabolism   MeSH
• Models, Biological MeSH
• Cell Membrane metabolism   MeSH
• Chemotaxis MeSH
• Cytoskeleton metabolism   MeSH
• Phosphoproteins metabolism   MeSH
• Phosphorylation MeSH
• Glucuronidase metabolism   MeSH
• Immunoglobulin Fab Fragments chemistry   MeSH
• Rats MeSH
• Mast Cells cytology   MeSH
• Membrane Proteins metabolism   MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Rats, Wistar MeSH
• Receptors, IgE metabolism   MeSH
• Amino Acid Transport System y+ metabolism   MeSH
• Tyrosine chemistry   MeSH
• Calcium metabolism   MeSH
• Protein Binding MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Adaptor Proteins, Signal Transducing MeSH
• Tetraspanin 29 MeSH
• Fusion Regulatory Protein 1, Light Chains MeSH
• Antigens MeSH
• Phosphoproteins MeSH
• Glucuronidase MeSH
• Immunoglobulin Fab Fragments MeSH
• Lat protein, mouse MeSH Browser
• Lat protein, rat MeSH Browser
• Membrane Proteins MeSH
• Receptors, IgE MeSH
• SLC7A8 protein, mouse MeSH Browser
• Slc7a8 protein, rat MeSH Browser
• Amino Acid Transport System y+ MeSH
• Tyrosine MeSH
• Calcium MeSH