This is an application to study the biological function of the CD44 molecule of activated T lymphocytes, and to define the parameters that determine high affinity binding of this receptor to the extracellular matrix. Hyaluronan is a specific ligand of CD44 and although abundant very few T-cells bind to it despite expressing the receptor, albeit in an inactive form. The goal of this application is to identify the mechanism that conveys a low affinity (non-binding) CD44 molecule to a high affinity one. In cellular terms high affinity-binding appears to be a feature of activated T-cells, and it follows that the expression of this high affinity-receptor is a regulated event. The biological implications are directed migration in inflammation and metastasis. In more specific terms, one can distinguish between an inactive binding state, an inductive one and a constitutive one. The PI has succeeded in deriving mutant cell lines that represent these three phenotypes, allowing the detailed study proposed here of the molecular conditions governing the three binding states. An important lead has been the demonstration that distinct N-glycosylation patterns are correlated with presence or absence of hyaluronan binding. Using transfections with mutants of glycosylation sites it was shown that absence of carbohydrate on one site at position 25 confers constitutive hyaluronan binding activity on an otherwise inducible cell line. These experiments leave little doubt that N glycosylation implies the action of trans acting genes, and since results of a number of biological experiments, including somatic hybridization, also postulate the existence of 2 genes modulating the CD44 function, the search is on to identify these, A transfection strategy free of prejudice regarding the function of such genes is proposed for their isolation. Finally in the third aim, the immunological function of CD44 is approached by studying the role of CD44 in mediating lymphocyte trafficking.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI031613-09
Application #
6169675
Study Section
Immunobiology Study Section (IMB)
Program Officer
Plaut, Marshall
Project Start
1992-05-01
Project End
2002-02-28
Budget Start
2000-07-01
Budget End
2002-02-28
Support Year
9
Fiscal Year
2000
Total Cost
$399,887
Indirect Cost
Name
Salk Institute for Biological Studies
Department
Type
DUNS #
078731668
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Lesley, Jayne; Gal, Istvan; Mahoney, David J et al. (2004) TSG-6 modulates the interaction between hyaluronan and cell surface CD44. J Biol Chem 279:25745-54
Gal, Istvan; Lesley, Jayne; Ko, Wendy et al. (2003) Role of the extracellular and cytoplasmic domains of CD44 in the rolling interaction of lymphoid cells with hyaluronan under physiologic flow. J Biol Chem 278:11150-8
Hyman, Robert (2002) Lack of a consistent relationship between demethylation of the CD44 promoter and CD44 expression. Immunogenetics 53:914-24
Lesley, Jayne; English, Nicole M; Gal, Istvan et al. (2002) Hyaluronan binding properties of a CD44 chimera containing the link module of TSG-6. J Biol Chem 277:26600-8
Lesley, J; Hascall, V C; Tammi, M et al. (2000) Hyaluronan binding by cell surface CD44. J Biol Chem 275:26967-75
Kim, J H; Glant, T T; Lesley, J et al. (2000) Adhesion of lymphoid cells to CD44-specific substrata: the consequences of attachment depend on the ligand. Exp Cell Res 256:445-53
Lesley, J; English, N; Charles, C et al. (2000) The role of the CD44 cytoplasmic and transmembrane domains in constitutive and inducible hyaluronan binding. Eur J Immunol 30:245-53
English, N M; Lesley, J F; Hyman, R (1998) Site-specific de-N-glycosylation of CD44 can activate hyaluronan binding, and CD44 activation states show distinct threshold densities for hyaluronan binding. Cancer Res 58:3736-42
Perschl, A; Lesley, J; English, N et al. (1995) Role of CD44 cytoplasmic domain in hyaluronan binding. Eur J Immunol 25:495-501
Perschl, A; Lesley, J; English, N et al. (1995) Transmembrane domain of CD44 is required for its detergent insolubility in fibroblasts. J Cell Sci 108 ( Pt 3):1033-41

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