This is a continuation application to study the molecular regulation, structure and function of the low affinity IgE receptor (Fc-epsilon-RII), using the mouse system. The overall aim is to gain further insight into the roles this molecule plays in immediate hypersensitivity and in B-cell activation and differentiation.
In aim number 1 the molecular mechanism of IL-4 induced Fc-epsilon-RII up-regulation will be determined. The promoter region of the murine Fc-epsilon-RII gene has been tentatively identified using CAT reporter plasmids. This will be further defined with additional deletion studies and the region that responds to IL-4 will be determined. The mechanism will then be further explored by analysis of DNA-binding proteins that may interact with the IL-4 responsive element. Finally, the role that mRNA stabilization plays in the IL-4- induced Fc-epsilon-RII regulation will also be determined.
In aim number 2, the Fc-epsilon-RII structure necessary for IgE binding will be determined. Current results indicate that the Fc- epsilon-RII forms a trimeric structure analogous to other """"""""coiled-coil"""""""" molecules such as tropomyosin. The region responsible for this receptor- receptor interaction has been identified; it is termed the """"""""stalk"""""""" region of the Fc-epsilon-RII. Additional deletion mutant Fc-epsilon-RII as well as chimeric Fc-epsilon-RII in which the lectin homologous region is attached to the other C-type family """"""""stalk"""""""" will be prepared and analyzed for IgE- binding and oligomer formation. A variety of new biologic activities for the sFc-epsilon-RII have been described in humans.
In aim number 3 the soluble Fc-epsilon-RII constructs prepared in aim number 2 will be analyzed for biologic activity. The sFc- epsilon-RII constructs will be tested for activity against mast cells with respect to mediator and cytokine release and B-cells with respect to costimulation, IgE production and inhibition of a proptosis. These studies will also allow the determination of whether a ligand other than IgE exists for the Fc-epsilon-RII. Two biologic activities for the intact Fc-epsilon-RII have been identified in the current grant period--enhancement of antigen presentation and modification of anti-Ig mediated B-cell activation. Using the mutant Fc-epsilon-RII molecules produced in aim number 2, the correlation between capacity for oligomer formation and biologic activity will be determined.In addition, these mutants, as well as a mutant Fc-epsilon-RII lacking a cytoplasmic tail will be examined for the capacity to modulate internalization and cytoskeletal association. Finally, as these findings indicate new roles for IgE complexes, the effect of in vivo targeting the Fc-epsilon-RII on TH phenotype will be assayed.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
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Immunological Sciences Study Section (IMS)
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Virginia Commonwealth University
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Martin, Rebecca K; Damle, Sheela R; Valentine, Yolander A et al. (2018) B1 Cell IgE Impedes Mast Cell-Mediated Enhancement of Parasite Expulsion through B2 IgE Blockade. Cell Rep 22:1824-1834
Damle, S R; Martin, R K; Cockburn, C L et al. (2018) ADAM10 and Notch1 on murine dendritic cells control the development of type 2 immunity and IgE production. Allergy 73:125-136
Damle, Sheela R; Martin, Rebecca K; Cross, Janet V et al. (2017) Macrophage migration inhibitory factor deficiency enhances immune response to Nippostrongylus brasiliensis. Mucosal Immunol 10:205-214
Lownik, Joseph C; Luker, Andrea J; Damle, Sheela R et al. (2017) ADAM10-Mediated ICOS Ligand Shedding on B Cells Is Necessary for Proper T Cell ICOS Regulation and T Follicular Helper Responses. J Immunol 199:2305-2315
Cooley, Lauren Folgosa; El Shikh, Mohey Eldin; Li, Wei et al. (2016) Impaired immunological synapse in sperm associated antigen 6 (SPAG6) deficient mice. Sci Rep 6:25840
Cooley, Lauren Folgosa; Martin, Rebecca K; Zellner, Hannah B et al. (2015) Increased B Cell ADAM10 in Allergic Patients and Th2 Prone Mice. PLoS One 10:e0124331
Martin, Rebecca K; Brooks, Keith B; Henningsson, Frida et al. (2014) Antigen transfer from exosomes to dendritic cells as an explanation for the immune enhancement seen by IgE immune complexes. PLoS One 9:e110609
Martin, Rebecca K; Saleem, Sheinei J; Folgosa, Lauren et al. (2014) Mast cell histamine promotes the immunoregulatory activity of myeloid-derived suppressor cells. J Leukoc Biol 96:151-9
Folgosa, Lauren; Zellner, Hannah B; El Shikh, Mohey Eldin et al. (2013) Disturbed follicular architecture in B cell A disintegrin and metalloproteinase (ADAM)10 knockouts is mediated by compensatory increases in ADAM17 and TNF-? shedding. J Immunol 191:5951-8
Schlosburg, Joel E; O'Neal, Scott T; Conrad, Daniel H et al. (2011) CB1 receptors mediate rimonabant-induced pruritic responses in mice: investigation of locus of action. Psychopharmacology (Berl) 216:323-31

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