The adapter protein Src homology 2 (SH2) domain-containing leukocyte protein of 76 kDa (SLP-76) is critical for multiple aspects of T cell development and function. Through its protein-binding domains, SLP-76 serves as a platform for the assembly of multiple enzymes and adapter proteins that function together to activate second messengers required for TCR signal propagation. The N terminus of SLP-76, which contains three tyrosines that serve as docking sites for SH2 domain-containing proteins, and the central proline-rich region of SLP-76 have been well studied and are known to be important for both thymocyte selection and activation of peripheral T cells. Less is known about the function of the C-terminal SH2 domain of SLP-76. This region inducibly associates with ADAP and HPK1. Combining regulated deletion of endogenous SLP-76 with transgenic expression of a SLP-76 SH2 domain mutant, we demonstrate that the SLP-76 SH2 domain is required for peripheral T cell activation and positive selection of thymocytes, a function not previously attributed to this region. This domain is also important for T cell proliferation, IL-2 production, and phosphorylation of protein kinase D and IκB. ADAP-deficient T cells display similar, but in some cases less severe, defects despite phosphorylation of a negative regulatory site on SLP-76 by HPK1, a function that is lost in SLP-76 SH2 domain mutant T cells.
This work was supported by the National Institutes of Health (to M.S.J. and G.A.K.) and by the Deutsche Forschungsgemeinschaft (GRK1167 to J.D., S.K., and B.S.; SFB854 TP10 to S.K.; and TP12 to S.K. and B.S.).
The online version of this article contains supplemental material.
- Received October 22, 2009.
- Accepted August 22, 2011.
- Copyright © 2011 by The American Association of Immunologists, Inc.