title: Differential recruitment of accessory molecules by FcgammaRI during monocyte differentiation.
abstract: Aggregation of the human high-affinity receptor for immunoglobulin G, FcgammaRI, results in initiation of intracellular signaling cascades. However, as the receptor contains no known signaling motif, it is required to recruit an accessory molecule. The gamma chain has been proposed to fulfil this role. Here, we show that in U937 cells differentiated to a more macrophage-like phenotype with dibutyryl cAMP, FcgammaRI no longer signals through the gamma chain but rather uses FcgammaRIIa to initiate tyrosine phosphorylation. Expression of the gamma chain is, however, increased in the dbcAMP-induced cells, but here the gamma chain specifically associates with the IgA receptor, FcalphaRI. Recruitment of the gamma chain either by FcgammaRI in cytokine-primed cells or by FcalphaRI in dbcAMP-induced cells couples ligand binding to the activation of phosphatidyl choline-specific phospholipase D.
authors.affiliation: Department of Medicine & Therapeutics and Division of Biochemistry & Molecular Biology, University of Glasgow, Glasgow, GB.
authors.forename: A J
authors.initials: AJ
authors.lastname: Cameron
authors.forename: M M
authors.initials: MM
authors.lastname: Harnett
authors.forename: J M
authors.initials: JM
authors.lastname: Allen
mesh_terms: D000936:Antigen-Antibody Complex / Q000378:metabolism / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D003994:Bucladesine / Q000494:pharmacology; D002454:Cell Differentiation; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D009000:Monocytes / Q000276:immunology*; D010713:Phosphatidylcholines / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D011961:Receptors, Fc / Q000378:metabolism; D017452:Receptors, IgG / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction; D020298:U937 Cells
chemical_list: D000936:Antigen-Antibody Complex; D015703:Antigens, CD; C036832:Fc(alpha) receptor; D010713:Phosphatidylcholines; D012333:RNA, Messenger; D011961:Receptors, Fc; D017452:Receptors, IgG; D003994:Bucladesine; D007371:Interferon-gamma; D010739:Phospholipase D