Engagement of the T cell antigen receptor (TCR) initiates a cascade of signaling events that ultimately leads to cytokine gene expression, cellular proliferation and induction of T-cell effector functions. Non-receptor protein tyrosine kinases (PTKs) link the TCR with proximal signaling events through tyrosine phosphorylation of multiple adapter and effector proteins. These events lead to the activation of multiple biochemical pathways in the cytoplasm and signals to the nucleus. One of the key cytoplasmic enzymes activated upon TCR ligation by the PTKs is phospholipase C-gamma1 (PLC-gamma1). The enzymatic role of PLC-gamma1 in generating second messengers has been well documented. More recently, studies done using genetically deficient Jurkat T cell lines and gene-targeted mice have shown that optimal tyrosine phosphorylation of PLC-gamma1 requires the activity of multiple PTKs and adapter proteins. We have identified the adapter SKAP-HOM in a three-hybrid screen designed to find phosphoproteins that interact with PLC-gamma1. Using the powerful new technique of siRNA, we have knocked down expression ot SKAP55, a SKAP-HOM related protein, in Jurkat T cells and found a novel role for this adapter as a negative regulator of TCR signaling.
The specific aims of this proposal are: (1) to elucidate the molecular mechanism by which SKAP55 negatively regulates PLC-gamma1 signaling in the Jurkat T cell line (2) to determine the basis of the SKAP55-PLC-gamma1 interaction and the role of the SKAP55 PH domain (3) to use knock-down technology to explore the function of SKAP55 and SKAP-HOM in non-transformed human T cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
5F32AI056895-03
Application #
6910830
Study Section
Special Emphasis Panel (ZRG1-F07 (20))
Program Officer
Prograis, Lawrence J
Project Start
2003-07-01
Project End
2006-06-30
Budget Start
2005-07-01
Budget End
2006-06-30
Support Year
3
Fiscal Year
2005
Total Cost
$49,928
Indirect Cost
Name
Sanford-Burnham Medical Research Institute
Department
Type
DUNS #
020520466
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Kosco, Karena A; Cerignoli, Fabio; Williams, Scott et al. (2008) SKAP55 modulates T cell antigen receptor-induced activation of the Ras-Erk-AP1 pathway by binding RasGRP1. Mol Immunol 45:510-22