Cutting Edge: MicroRNA Regulation of Macrophage Fusion into Multinucleated Giant Cells

This is the authors' abstract. We don't add key points for this paper.

Cellular fusion of macrophages into multinucleated giant cells is a distinguishing feature of the granulomatous response to inflammation, infection, and foreign bodies (Kawai and Akira. 2011. Immunity 34: 637-650). We observed a marked increase in fusion of macrophages genetically deficient in Dicer, an enzyme required for canonical microRNA (miRNA) biogenesis. Gene expression profiling of miRNA-deficient macrophages revealed an upregulation of the IL-4-responsive fusion protein Tm7sf4, and analyses identified miR-7a-1 as a negative regulator of macrophage fusion, functioning by directly targeting Tm7sf4 mRNA. miR-7a-1 is itself an IL-4-responsive gene in macrophages, suggesting feedback control of cellular fusion. Collectively, these data indicate that miR-7a-1 functions to regulate IL-4-directed multinucleated giant cell formation.