Rheb1-mTORC1 maintains macrophage differentiation and phagocytosis in mice.

Ras homolog enriched in brain (Rheb1) is a small GTPase and is known to be a direct activator of mTORC1. Dysregulation of Rheb1 has been shown to impair the cellular-energetic state and cell homeostasis. However, the role of Rheb1 in monocytes/macrophages differentiation and maturation is not clear. Here, we investigate the role of Rheb1 in mouse myelopoiesis using a Rheb1 conditional deletion murine model. We found that the absolute number of macrophages decreased in the bone marrow (BM) of Rheb1-deficient mice. Loss of Rheb1 inhibited the monocyte-to-macrophage differentiation process. Additionally, Rheb1 deletion reduced phagocytosis ability of macrophages by inhibiting the mTORC1 signaling pathway. Furthermore, 3BDO (an activator of mTORC1) rescued the phagocytosis ability of Rheb1-deficient macrophages. Thus, Rheb1 is critical for macrophage production and phagocytosis and executes these activities possibly via mTORC1-dependent pathway.