CD43-specific activation of T cells induces association of CD43 to Fyn kinase.
CD43, the most abundant membrane protein of T lymphocytes, is able to initiate signal transduction pathways that lead to Ca2+ mobilization and interleukin-2 production, yet the molecular events involved in CD43's signal transduction pathway are poorly understood. In the present report we show that activation of both purified T lymphocytes and Jurkat cells, through CD43 cross-linking with the anti-CD43 L10 monoclonal antibody, induced CD43 association to Fyn kinase. This association is mediated by the Src homology 3 (SH3) domain of Fyn, since a glutathione S-transferase-Fyn SH3 fusion protein was able to precipitate CD43 from lysates of CD43-activated T cells. A synthetic peptide containing the SH3 binding sites of p85, located within the amino acid sequence 300ERQPAPALPPKPPKP314, was able to inhibit binding of CD43 to Fyn as well as to the glutathione S-transferase-Fyn SH3 fusion protein. We also provide evidence that upon CD43 cross-linking, Fyn is tyrosine-phosphorylated in a time-dependent manner. Our results suggest that CD43 cross-linking on the T cell surface induces the interaction between CD43 and Fyn, presumably through the Fyn SH3 domain and a putative SH3 binding site in CD43, leading to Fyn tyrosine phosphorylation and signal propagation.
Pedraza-Alva
G
G
Instituto de Biotecnología/Universidad Nacional Autónoma de Mexico, Apartado Postal 510-3 Cuernavaca, Morelos 62250, México.
Mérida
L B
LB
Burakoff
S J
SJ
Rosenstein
Y
Y
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D016384:Consensus Sequence; D003432:Cross-Linking Reagents; D005434:Flow Cytometry; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology*; D018909:src Homology Domains
D000911:Antibodies, Monoclonal; D018797:Cell Cycle Proteins; D003432:Cross-Linking Reagents; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D005982:Glutathione Transferase; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn