Submitted September 5, 2008
Accepted April 18, 2009
The importance of SLP-76 SAM domain in thymic selection and T cell activation
Shudan Shen, Jasmine Lau, Minghua Zhu, Jianwei Zou, Deirdre Fuller, Qi-jing Li, and Weiguo Zhang*
Department of Immunology, Duke University Medical Center, Durham, NC, United States
* Corresponding author; email: zhang033{at}mc.duke.edu.
The SH2 domain-containing leukocyte phosphoprotein of 76 KD (SLP-76) is a cytosolic adaptor protein essential for thymocyte development and T cell activation. It contains a SAM (sterile-alpha motif) domain, three phosphotyrosine motifs, a proline-rich region, and a SH2 domain. While the other domains have been extensively studied, the role of the SAM domain in SLP-76 function is not known. To understand the function of this domain, we generated SLP-76 knock-in mice with the SAM domain deleted. Analysis of these mice showed that thymocyte development was partially blocked at the DP to SP transition. Positive and negative thymic selection was also impaired. Additionally, we analyzed TCR-mediated signaling in T cells from these mutant mice. TCR-mediated IP3 production, calcium flux, and ERK activation were decreased, leading to defective IL-2 production and proliferation. Moreover, despite normal association between GADS and SLP-76, TCR-mediated formation of SLP-76 microclusters was impaired by the deletion of the SAM domain. Altogether, our data demonstrated that the SAM domain is indispensable for optimal SLP-76 signaling.
