Tumor necrosis factor induces a block in the cotranslation of Fc gamma RIIb mRNA in mouse peritoneal macrophages

Abstract

Macrophage activation results in the secretion of various proteins, such as inflammatory cytokines and proteases. In parallel, cell morphology is altered, and the repertoire of cell surface proteins is modified. One of the main functions of macrophages is phagocytosis via Fc gamma-receptors (Fc gamma R). This study explores the modulation of Fc gamma Rs and their mRNAs following activation of macrophages by tumor necrosis factor. It shows that the cell surface expression of Fc gamma RI and Fc gamma RIIb is strongly reduced in macrophages cultured in the presence of tumor necrosis factor, whereas the mRNA of the Fc gamma RIIb is strongly increased as the result of an increase in mRNA stability. Thus, Fc gamma RIIb expression is modulated during macrophage activation by a new mechanism involving posttranscriptional regulation.