Effect of redox balance alterations on cellular localization of LAT and downstream T-cell receptor signaling pathways.
The integral membrane protein linker for activation of T cells (LAT) is a central adapter protein in the T-cell receptor (TCR)-mediated signaling pathways. The cellular localization of LAT is extremely sensitive to intracellular redox balance alterations. Reduced intracellular levels of the antioxidant glutathione (GSH), a hallmark of chronic oxidative stress, resulted in the membrane displacement of LAT, abrogated TCR-mediated signaling and consequently hyporesponsiveness of T lymphocytes. The membrane displacement of LAT is accompanied by a considerable difference in the mobility of LAT upon native and nonreducing denaturing polyacrylamide gel electrophoresis analysis, a finding indicative of a conformational change. Targeted mutation of redox-sensitive cysteine residues within LAT created LAT mutants which remain membrane anchored under conditions of chronic oxidative stress. The expression of redox-insensitive LAT mutants allows for restoration of TCR-mediated signal transduction, whereas CD28-mediated signaling pathways remained impaired. These results are indicative that the membrane displacement of LAT as a result of redox balance alterations is a consequence of a conformational change interfering with the insertion of LAT into the plasma membrane. Conclusively, the data suggest a role for LAT as a crucial intermediate in the sensitivity of TCR signaling and hence T lymphocytes toward chronic oxidative stress.
Gringhuis
Sonja I
SI
Department of Rheumatology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands. s.i.gringhuis@lumc.nl
Papendrecht-van der Voort
Ellen A M
EA
Leow
Angela
A
Nivine Levarht
E W
EW
Breedveld
Ferdinand C
FC
Verweij
Cornelis L
CL
D048868:Adaptor Proteins, Signal Transducing; D019943:Amino Acid Substitution; D018106:CD28 Antigens / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000235:genetics; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D021962:Membrane Microdomains / Q000378:metabolism; D008565:Membrane Proteins; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D011487:Protein Conformation; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D014162:Transfection
D048868:Adaptor Proteins, Signal Transducing; D018106:CD28 Antigens; D002352:Carrier Proteins; D007376:Interleukin-2; C110810:LAT protein, human; D008565:Membrane Proteins; D016328:NF-kappa B; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell