A regulatory role for cytoplasmic YVKM motif in CTLA-4 inhibition of TCR signaling
✍ Scribed by Helga Schneider; Silvy da Rocha Dias; Hui Hu; Christopher E. Rudd
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 168 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0014-2980
No coin nor oath required. For personal study only.
✦ Synopsis
CTLA-4 negatively regulates TCR signaling, although the molecular basis for this effect has yet to be elucidated. The cytoplasmic YVKM motif, while binding to phosphatidylinositol 3kinase, SHP-2 and the AP-1/AP-2 clathrin adaptor complexes, has been reported to play no role in CTLA-4 function. In contrast, in this study, we demonstrate that, although not essential, the YVKM motif contributes to optimal CTLA-4 blockage of TCR ´or combined TCR
´/ CD28 signaling. Significantly, dependency on the YVKM motif varied with the mode of antireceptor presentation, where soluble antibody ligation was more dependent on the presence of the motif than immobilized antibody. Previous studies have mainly relied on the use of immobilized antibody. Neither SHP-2 binding, alterations in TCR ´chain phosphorylation, nor ZAP-70 recruitment was involved in CTLA-4 wild-type or mutant inhibition. Overall, our findings clearly implicate the YVKM motif in optimal CTLA-4 function.