title: HIV glycoprotein gp120 inhibits TCR-CD3-mediated activation of fyn and lck.
abstract: HIV major glycoprotein gp120 interacts with CD4 molecules and perturbs signaling through the TCR-CD3 complex. We examined the effects of gp120 on TCR-CD3-induced phosphorylation and activation of the src-type protein tyrosine kinases (PTK), fyn and lck. gp120 caused minimal changes in lck phosphorylation or lck enzymatic activity, but preincubation of Jurkat cells with gp120 for 20 min strongly inhibited TCR-CD3-mediated phosphorylation and activation of lck and fyn, as well as phosphorylation of CD3 zeta. Inhibition of TCR-CD3 signaling in T cells preincubated with gp120 was paralleled by inhibition of T cell proliferation to the antigen tetanus toxoid. Neither surface CD4 expression nor CD4-lck association was affected by gp120. Furthermore, gp120 inhibited lck phosphorylation induced by cross-linking of TCR-CD3 and CD4 suggesting that the inhibition of lck phosphorylation could not be simply accounted for by sequestration of CD4 molecules. gp120 selectively enhanced the phosphorylation of the lck peptide containing the autoinhibitory tyrosine residue Tyr505 relative to the lck peptide containing the positive regulatory residue Tyr394, suggesting that a qualitative alteration in lck may underlie the inhibition of TCR-CD3 signaling by gp120.
authors.affiliation: Division of Immunology, Children's Hospital, Boston, MA 02115, USA.
authors.forename: T
authors.initials: T
authors.lastname: Morio
authors.forename: T
authors.initials: T
authors.lastname: Chatila
authors.forename: R S
authors.initials: RS
authors.lastname: Geha
mesh_terms: D015704:CD4 Antigens / Q000096:biosynthesis / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D015699:HIV Envelope Protein gp120 / Q000494:pharmacology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000187:drug effects; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors*; D051076:Proto-Oncogene Proteins c-fyn; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects; D013745:Tetanus Toxoid / Q000494:pharmacology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism
chemical_list: D015704:CD4 Antigens; D015699:HIV Envelope Protein gp120; D011518:Proto-Oncogene Proteins; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D013745:Tetanus Toxoid; D011505:Protein-Tyrosine Kinases; C494957:FYN protein, human; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases