The IgE receptor on mast cells and basophils (Fcepsilone R-I) is directly involved in the IgE-mediated activation of these cells. Recently, cDNA coding for the alpha-subunit of the rat Fcepsilone R-I (Fcepsilone R-Ialpha) has been cloned. RNA heterogeneity was subsequently detected, suggesting the presence of variants of Fc epsilone R-Ialpha, including the possible presence of intracellular forms and secretory truncated forms of Fc epsilone R-Ialpha. A new IgE-binding protein, epsilone BP, was found to contain interesting structural features, but its function is yet to be defined. In this research program, we will continue our studies of both Rc epsilone R-I and epsilone BP. First, structure-function relationship of rodent Fcepsilone R-I alpha will be established. Expression of cloned cDNA in mammalian cells by gene transfection will be conducted. Expression of both the surface membrane-bound form and soluble form of the receptor will be pursued. Mutant Fc epsilone R-I alpha in normal rat mast cells. Various protein products predicted from the cDNA cloning results, including the intracellular and secetory truncated forms of Fcepsilone R-I alphs will be generated for structure-function analysis to identify structural elements in FcepsiloneR-Ialphs that are involved in binding to IgE. Second, various forms of FcepsiloneR-Ialpha will be identified. RNase protection analysis and polymerase chain reaction methodology will be employed to identify various RNA forms related to FcepsiloneR-Ialpha in normal rat mast cells. Various protein products predicted from the cDNA cloning results, including the intracellular and secretory truncated forms of FcepsiloneR-Ialpha will be detected in RBL cells. Genomic DNA coding for mouse FCepsiloneR-Ialpha will be cloned and used to extend the above analysis to the mouse system. Third, function of the newly defiend IgE-binding protein (epsiloneBP) will be delineated. Cell types expressing epsilone and the location of epsilone in cells will be identified. If it is established that epsilone is not a cell suface receptor, its role as a soluble protein, regulating IgE synthesis or histamine release form mast cells and basophils will be explored. The long-term goals of this research are: 1) establishment of structure, function and regulation of key components of the IgE system; and 2) development of therapeutic methods for the treatment of human allergic disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI019747-10
Application #
3129138
Study Section
Immunological Sciences Study Section (IMS)
Project Start
1990-08-01
Project End
1994-02-28
Budget Start
1991-03-01
Budget End
1992-02-29
Support Year
10
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Zuberi, R I; Frigeri, L G; Liu, F T (1994) Activation of rat basophilic leukemia cells by epsilon BP, an IgE-binding endogenous lectin. Cell Immunol 156:1-12
Liu, F T; Shenhav, A; Bhat, B et al. (1994) Preparation and characterization of polyclonal and monoclonal antibodies specific for covalently linked DNA/RNA cross sections. Hybridoma 13:499-507
Liu, F T; Frigeri, L G; Gritzmacher, C A et al. (1993) Expression and function of an IgE-binding animal lectin (epsilon BP) in mast cells. Immunopharmacology 26:187-95
Yen, A; Liu, F T; Barrett, K E et al. (1993) Alterations in Fc epsilon RI induced by protoporphyrin plus long-wavelength ultraviolet light in mouse bone marrow-derived mast cells. J Immunol 151:1003-11
Wollenberg, A; de la Salle, H; Hanau, D et al. (1993) Human keratinocytes release the endogenous beta-galactoside-binding soluble lectin immunoglobulin E (IgE-binding protein) which binds to Langerhans cells where it modulates their binding capacity for IgE glycoforms. J Exp Med 178:777-85
Liu, F T (1993) S-type mammalian lectins in allergic inflammation. Immunol Today 14:486-90
Frigeri, L G; Liu, F T (1992) Surface expression of functional IgE binding protein, an endogenous lectin, on mast cells and macrophages. J Immunol 148:861-7
Gritzmacher, C A; Mehl, V S; Liu, F T (1992) Genomic cloning of the gene for an IgE-binding lectin reveals unusual utilization of 5' untranslated regions. Biochemistry 31:9533-8
Hsu, D K; Zuberi, R I; Liu, F T (1992) Biochemical and biophysical characterization of human recombinant IgE-binding protein, an S-type animal lectin. J Biol Chem 267:14167-74
Richards, M L; Katz, D H; Liu, F T (1991) Complete genomic sequence of the murine low affinity Fc receptor for IgE. Demonstration of alternative transcripts and conserved sequence elements. J Immunol 147:1067-74

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