The CD4 and CD8 antigens play important roles in immunity by binding to major histocompatibility complex (MHC) antigens and by synergizing with the TCR/CD3 complex in the generation of signals leading to T-cell proliferation. An important issue has been to establish the molecular mechanism by which the CD4/CD8 antigens regulate cell growth. Recently, I reported the novel finding that the CD4 and CD8 antigens are coupled to a protein-tyrosine kinase (p56-lck) from T lymphocytes. Importantly p56-lck is a member of the src family of tyrosine kinases (c-src, c-yes, c-abl, etc.) which have been causally linked to the activation and transformation of mammalian cells. p56-lck is also related to kinase domains which comprise the cytoplasmic tails of the insulin, and epidermal growth factor receptors. Thus, p56-lck may constitute the underlying molecular mechanism of CD4 and CD8 function in the regulation of T-cell growth. Regulation of p56-lck activity may also be important in the development of T cell malignancies and autoimmune disorders. Importantly, the CD4/CD8:p56-lck complex is catalytically active as shown by its ability to undergo autophosphorylation and to phosphorylate various subunits of the CD3 complex (including the CD3 zeta chain). The CD4/CD8:p56-lck complex may thus mediate the cooperative interaction between the Ti/CD3 complex and the CD4/CD8 antigens. In this proposal, we propose to extend this work with a detailed biochemical analysis of the CD4/CD8:p56-lck complex (its size, the identity of other components (4OKd, 8OKd) in the complex, whether p56-lck activity is regulated by ligand binding to CD4/CD8 and the TcR complex etc.). In addition, we will attempt to map the site of p56-lck binding to the cytoplasmic tail of the CD4/CD8 antigens by use of peptides, site-directed mutagenesis and transfection analysis. Lastly, we propose to study the function of P56-lck in the activation and transformation of T cells by transfection with sense and anti-sense p56-lck constructs in various antigen-specific T-cell hybridomas and transformed T cells. This comprehensive approach should provide valuable information on the role played by CD4/CD8:p56-lck complex in T-cell activation and potentially on the development of T-cell leukemias and various lymphoproliferative disorders.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA051887-04
Application #
3196601
Study Section
Allergy and Immunology Study Section (ALY)
Project Start
1990-06-01
Project End
1995-05-31
Budget Start
1993-06-01
Budget End
1994-05-31
Support Year
4
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Dana-Farber Cancer Institute
Department
Type
DUNS #
149617367
City
Boston
State
MA
Country
United States
Zip Code
02215
Liu, J; Kang, H; Raab, M et al. (1998) FYB (FYN binding protein) serves as a binding partner for lymphoid protein and FYN kinase substrate SKAP55 and a SKAP55-related protein in T cells. Proc Natl Acad Sci U S A 95:8779-84
da Silva, A J; Rosenfield, J M; Mueller, I et al. (1997) Biochemical analysis of p120/130: a protein-tyrosine kinase substrate restricted to T and myeloid cells. J Immunol 158:2007-16
Raab, M; da Silva, A J; Findell, P R et al. (1997) Regulation of Vav-SLP-76 binding by ZAP-70 and its relevance to TCR zeta/CD3 induction of interleukin-2. Immunity 6:155-64
Raab, M; Cai, Y C; Bunnell, S C et al. (1995) p56Lck and p59Fyn regulate CD28 binding to phosphatidylinositol 3-kinase, growth factor receptor-bound protein GRB-2, and T cell-specific protein-tyrosine kinase ITK: implications for T-cell costimulation. Proc Natl Acad Sci U S A 92:8891-5
Rudd, C E; Janssen, O; Cai, Y C et al. (1994) Two-step TCR zeta/CD3-CD4 and CD28 signaling in T cells: SH2/SH3 domains, protein-tyrosine and lipid kinases. Immunol Today 15:225-34
Prasad, K V; Janssen, O; Kapeller, R et al. (1993) Src-homology 3 domain of protein kinase p59fyn mediates binding to phosphatidylinositol 3-kinase in T cells. Proc Natl Acad Sci U S A 90:7366-70
Rothstein, D M; da Silva, A; Sugita, K et al. (1993) Human CD4/CD45RA+ and CD4/CD45RA- T cell subsets express CD4-p56lck complexes, CD4-associated lipid kinases, TCR/CD3-p59fyn complexes, and share similar tyrosine kinase substrates. Int Immunol 5:409-18
Prasad, K V; Kapeller, R; Janssen, O et al. (1993) Phosphatidylinositol (PI) 3-kinase and PI 4-kinase binding to the CD4-p56lck complex: the p56lck SH3 domain binds to PI 3-kinase but not PI 4-kinase. Mol Cell Biol 13:7708-17
da Silva, A J; Yamamoto, M; Zalvan, C H et al. (1992) Engagement of the TcR/CD3 complex stimulates p59fyn(T) activity: detection of associated proteins at 72 and 120-130 kD. Mol Immunol 29:1417-25