FIGURE 8.

Mammalian Gcn2 is involved in mTORC1 down-regulation in response to amino acid starvation. A, mTORC1-dependent phosphorylation of S6 and 4E-BP1 in wild type (Gcn2 +) and Gcn2 null MEF (Gcn2 −) cells grown under normal conditions. B, WT and Gcn2 null MEF cells were collected after exposure to leucine or histidine starvation for the indicated times. At the end of 2-h starvation, leucine (Leu) or histidine (His) was added back for 15 min. mTORC1 signaling activity in the starved cells and in those after adding back the omitted amino acids was determined by the mTORC1-dependent phosphorylation of S6 and 4E-BP1. The experiments were repeated five times, and representative data are shown.