Modulation of the electrophoretic mobility of the linker for activation of T cells (LAT) by the calcineurin inhibitors CsA and FK506: LAT is a potential substrate for PKC and calcineurin signaling pathways.
The linker for activation of T cells (LAT) is essential for T cell activation. Cyclosporin A (CsA) and FK506, inhibitors of T cell proliferation, have been very useful for preventing autoimmune and inflammatory disease and graft rejection. However, both compounds are associated with side effects. We show that TCR ligation in the presence of FK506 or CsA induced rapid modifications in LAT that modulate the electrophoretic mobility of the molecule in SDS-PAGE. Calcineurin, a target for CsA and FK506, dephosphorylated LAT in vitro and restored its electrophoretic mobility. Stimulating T cells with the protein kinase C (PKC) activator PMA induced a shift in the mobility of LAT, whereas inhibitors of PKC blocked the effect of PMA. Thus, manipulating calcineurin or PKC activation alters the electrophoretic mobility of LAT. These results shed light on the molecular actions of CsA and FK506 in T cells and implicate LAT in mediating the drugs' actions.
Cho
Clifford S
CS
Department of Surgery, Division of Transplantation, University of Wisconsin, H4/749, CSC, 600 Highland Avenue, Madison, WI 53792, USA.
Elkahwaji
Johny
J
Chang
Zheng
Z
Scheunemann
Tara L
TL
Manthei
Eric R
ER
Hamawy
Majed M
MM
D048868:Adaptor Proteins, Signal Transducing; D019703:Calcineurin / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000032:analysis* / Q000378:metabolism; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D019169:Jurkat Cells; D007700:Kinetics; D008565:Membrane Proteins; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D010750:Phosphoproteins / Q000032:analysis* / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology; D016559:Tacrolimus / Q000494:pharmacology*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D007166:Immunosuppressive Agents; C110810:LAT protein, human; D008565:Membrane Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; D016572:Cyclosporine; D011493:Protein Kinase C; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D002118:Calcium; D020123:Sirolimus; D016559:Tacrolimus