Low affinity Fcγ receptors on murine macrophages:: mitogen-activated protein kinase activation and AP-1 DNA binding activity

Mouse macrophage cell lines such as J774 express Fc receptors for IgG2a immune complexes, which upon binding of the proper ligand, trigger several signal transduction pathways. A surface to nucleus signaling through these receptors has been demonstrated. We describe here the activation of the mitogen-activated protein kinase (MAPK) and an increase in the binding of the activator protein 1 (AP-1) to DNA upon receptor stimulation. The described effects are only partially blocked by inhibitors of the Ca(2+)/diacylglycerol-depcndent protein kinase (PRC), suggesting that differential signaling pathways are activated upon receptor cross-linking and that they converge at or above the MAPK level. These results pave the way to our understanding of Fc gamma R cross-linking induced gene expression regulation. (C) 1999 Elsevier Science B.V. All rights reserved.