C/EBPβ is required for survival of Ly6C monocytes.

The transcription factor CCAAT/enhancer-binding protein β (C/EBPβ) is highly expressed in monocytes/macrophages. However, its roles in monopoiesis are largely unknown. Here, we investigated the roles of C/EBPβ in monopoiesis. Further subdivision of monocytes revealed that messenger RNA was highly upregulated in Ly6C monocytes in bone marrow. Accordingly, the number of Ly6C monocytes was significantly reduced in mice. Bone marrow chimera experiments and -Cre-mediated deletion of revealed a cell-intrinsic and monocyte-specific requirement for C/EBPβ in monopoiesis. In mice, turnover of Ly6C monocytes was highly accelerated and apoptosis of Ly6C monocytes was increased. Expression of , which encodes a receptor for macrophage colony-stimulating factor, was significantly reduced in Ly6C monocytes of mice. C/EBPβ bound to positive regulatory elements of and promoted its transcription. Collectively, these results indicate that C/EBPβ is a critical factor for Ly6C monocyte survival, at least in part through upregulation of