A process of fundamental importance in immunology is the binding of antigen to cell surface-associated immunoglobulin that leads to transmembrane signaling in specialized cells. Antigen-mediated crosslinking of immunoglobulin E-receptor complexes on mast cells and basophils leads to degranulation in the allergic response, while crosslinking of surface immunoglobulin on B lymphocytes by certain antigens is a primary singal for proliferation and differentiation into antibody secreting cells. The critical molecular features of the crosslinking events that lead to a bioloogical response in either of these systems are not understood, and the proposed studies are aimed at elucidating these features. In previous studies on the IgE-receptor system, fluorescence methods have been developed that have allowed the kinetics of binding and crosslinking by model bivalent antigens to e determined. These studies have revealsed that some bivalent antigens can crosslink IgE-receptor complexes very efficiently on the cell surface, yet trigger only a small cellulr degranulation response. Properties such as rate of crosslinking, crosslink lifetime, and rate of dissociation for these antigens will be compared with those of other bivalent antigens that trighger a much stronger biological response. By this means the relationship between these kinetic properties, activation, and inactivation (densensitization) signals will be investigated. Structural factors also play a role in determining the efficacy of crosslinking, and these will be studied using model bivalent antigens of different lengths. Distances between IgE-receptor complexes crosslinked by long, rigid bivalent antigens that trigger degranulation will be mapped by electron microscopic and resonance energy transfer methods. The methodologies developed on the IgE-receptor system will be extended to studies of model antigen binding and crosslinking of dansyl-specific surface immunoglobulin on B cells and hybridoma cell lines. These studies will determine whether the features of crosslinking that are critical for signal tranduction by IgE- receptor complexes on mast cells are also important for transmembrane signaling by surface immunoglobulin on B cells.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
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Allergy and Immunology Study Section (ALY)
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Cornell University
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United States
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Holowka, David; Baird, Barbara (2017) Mechanisms of epidermal growth factor receptor signaling as characterized by patterned ligand activation and mutational analysis. Biochim Biophys Acta Biomembr 1859:1430-1435
Korzeniowski, Marek K; Wisniewski, Eva; Baird, Barbara et al. (2017) Molecular anatomy of the early events in STIM1 activation - oligomerization or conformational change? J Cell Sci 130:2821-2832
Holowka, David; Baird, Barbara (2016) Roles for lipid heterogeneity in immunoreceptor signaling. Biochim Biophys Acta 1861:830-836
Wilson, Joshua D; Shelby, Sarah A; Holowka, David et al. (2016) Rab11 Regulates the Mast Cell Exocytic Response. Traffic 17:1027-41
Sun, Chao; Wakefield, Devin L; Han, Yimo et al. (2016) Graphene Oxide Nanosheets Stimulate Ruffling and Shedding of Mammalian Cell Plasma Membranes. Chem 1:273-286
Korzeniowski, Marek K; Baird, Barbara; Holowka, David (2016) STIM1 activation is regulated by a 14 amino acid sequence adjacent to the CRAC activation domain. AIMS Biophys 3:99-118
Holowka, David; Wilkes, Marcus; Stefan, Christopher et al. (2016) Roles for Ca2+ mobilization and its regulation in mast cell functions: recent progress. Biochem Soc Trans 44:505-9
Cohen, Roy; Holowka, David A; Baird, Barbara A (2015) Real-time imaging of Ca(2+) mobilization and degranulation in mast cells. Methods Mol Biol 1220:347-63
Bryant, Kirsten L; Baird, Barbara; Holowka, David (2015) A novel fluorescence-based biosynthetic trafficking method provides pharmacologic evidence that PI4-kinase III? is important for protein trafficking from the endoplasmic reticulum to the plasma membrane. BMC Cell Biol 16:5
Holowka, David; Korzeniowski, Marek K; Bryant, Kirsten L et al. (2014) Polyunsaturated fatty acids inhibit stimulated coupling between the ER Ca(2+) sensor STIM1 and the Ca(2+) channel protein Orai1 in a process that correlates with inhibition of stimulated STIM1 oligomerization. Biochim Biophys Acta 1841:1210-6

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