and Specific Aims.) T-cell activation in response to antigen depends upon stimulation of the T cell antigen receptor and upon signals delivered through accessory T cell molecules, such as CD28. CD28 binds B7 (CD80) and B7-2 (B70), cell-surface molecules expressed by antigen-presenting cells. The current application seeks to define the structural basis for CD28- mediated signaling, with the goal of shedding light on the relationships between signaling pathways and cellular responses. Previous studies have shown that perturbation of CD28 induces its tyrosine phosphorylation. The first specific aim is to characterize the CD28- mediated signals that require cytoplasmic tyrosine residues. CD28 mutants with Phe for Tyr substitutions will be used to determine which Tyr residues are required in order for CD28 to elicit particular early signaling events and to mediate certain cellular responses. In addition, proteins whose interaction with CD28 requires these Tyr residues will be identified. Also, a 50 kD protein that binds CD28 at Tyr 170 and is closely related to phosphatidylinositol 3'-kinase p85 will be characterized. The second specific aim is to determine the importance of the interaction of CD28 with p72itk/emt which is a member of the tec family protein tyrosine kinases. The third specific aim will use a yeast two hybrid system to identify proteins that can interact with the cytoplasmic domain of CD28 independently of its phosphorylation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI026644-11
Application #
6169781
Study Section
Immunobiology Study Section (IMB)
Program Officer
Quill, Helen R
Project Start
1988-08-01
Project End
2004-06-30
Budget Start
2000-07-01
Budget End
2001-06-30
Support Year
11
Fiscal Year
2000
Total Cost
$283,873
Indirect Cost
Name
University of California San Francisco
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
073133571
City
San Francisco
State
CA
Country
United States
Zip Code
94143
Sadra, Ali; Cinek, Tomas; Imboden, John B (2004) Translocation of CD28 to lipid rafts and costimulation of IL-2. Proc Natl Acad Sci U S A 101:11422-7
Chikuma, Shunsuke; Imboden, John B; Bluestone, Jeffrey A (2003) Negative regulation of T cell receptor-lipid raft interaction by cytotoxic T lymphocyte-associated antigen 4. J Exp Med 197:129-35
Cinek, T; Sadra, A; Imboden, J B (2000) Cutting edge: tyrosine-independent transmission of inhibitory signals by CTLA-4. J Immunol 164:8-May
Sadra, A; Cinek, T; Imboden, J B (2000) Multiple probing of an immunoblot membrane using a non-block technique: advantages in speed and sensitivity. Anal Biochem 278:235-7
Sadra, A; Cinek, T; Arellano, J L et al. (1999) Identification of tyrosine phosphorylation sites in the CD28 cytoplasmic domain and their role in the costimulation of Jurkat T cells. J Immunol 162:1966-73
Barz, C; Nagel, T; Truitt, K E et al. (1998) Mutational analysis of CD28-mediated costimulation of Jun-N-terminal kinase and IL-2 production. J Immunol 161:5366-72
Truitt, K E; Nagel, T; Suen, L F et al. (1996) Structural requirements for CD28-mediated costimulation of IL-2 production in Jurkat T cells. J Immunol 156:4539-41
Truitt, K E; Shi, J; Gibson, S et al. (1995) CD28 delivers costimulatory signals independently of its association with phosphatidylinositol 3-kinase. J Immunol 155:4702-10
Truitt, K E; Hicks, C M; Imboden, J B (1994) Stimulation of CD28 triggers an association between CD28 and phosphatidylinositol 3-kinase in Jurkat T cells. J Exp Med 179:1071-6
Truitt, K E; Mills, G B; Turck, C W et al. (1994) SH2-dependent association of phosphatidylinositol 3'-kinase 85-kDa regulatory subunit with the interleukin-2 receptor beta chain. J Biol Chem 269:5937-43

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