Engagement of MHC class II molecules by staphylococcal superantigens activates src-type protein tyrosine kinases.
Staphylococcal exotoxins (SE) are superantigens that bind to monomorphic determinants on major histocompatibility complex (MHC) class II molecules and stimulate human peripheral blood T lymphocytes in a V beta-specific manner. SE also deliver activation signals via MHC class II molecules that initiate cell adhesion and cytokine gene transcription. These events are preceded by tyrosine phosphorylation and are antagonized by inhibitors of tyrosine kinases, indicating an essential role for these kinases in signaling via class II molecules. We report that stimulation of human peripheral blood monocytes with SE induced rapid and selective activation of the src-related protein tyrosine kinases (PTK) fgr and hck. SE also induced the activation of fgr and lyn in B cells. PTK activation by SE required MHC class II expression, and was greatly potentiated in the presence of T cells bearing toxin-specific V beta chains. These results indicate that in addition to their antigen and superantigen-presenting function, MHC class II molecules act as signal-transducing receptors that are coupled to src-type PTK.
Morio
T
T
Division of Immunology, Children's Hospital, Boston, MA.
Geha
R S
RS
Chatila
T A
TA
D001427:Bacterial Toxins; D004768:Enterotoxins / Q000276:immunology; D004789:Enzyme Activation; D006681:HLA-D Antigens / Q000276:immunology*; D006801:Humans; D009000:Monocytes / Q000378:metabolism*; D010449:Peptide Mapping; D010766:Phosphorylation; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051076:Proto-Oncogene Proteins c-fyn; D051572:Proto-Oncogene Proteins c-hck; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D015398:Signal Transduction; D013210:Staphylococcus / Q000276:immunology*; D018089:Superantigens / Q000276:immunology*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D019061:src-Family Kinases
D001427:Bacterial Toxins; D004768:Enterotoxins; D006681:HLA-D Antigens; D011518:Proto-Oncogene Proteins; D018089:Superantigens; C030107:enterotoxin F, Staphylococcal; C019368:enterotoxin D, Staphylococcal; D019000:Phosphotyrosine; C026066:enterotoxin A, Staphylococcal; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C494957:FYN protein, human; C496631:HCK protein, human; D051076:Proto-Oncogene Proteins c-fyn; D051572:Proto-Oncogene Proteins c-hck; D016392:Proto-Oncogene Proteins pp60(c-src); C060902:lyn protein-tyrosine kinase; C053102:proto-oncogene proteins c-fgr; D019061:src-Family Kinases