Fig. 3: Nutrient-dependent inhibition of mTORC1 by p53 and RFX7.
From: p53-mediated AKT and mTOR inhibition requires RFX7 and DDIT4 and depends on nutrient abundance
Western blot analysis of U2OS cells transfected with indicated siRNAs, treated with 10 µM Nutlin-3a or DMSO control, and cultured in DMEM and (A) HPLM or (C) DMEMphysio. A complementary replicate of (A) with additional measurements is available through Supplementary Fig. 1. B Western blot analysis of RPE-1 and HCTT116 cells transfected with indicated siRNAs, treated with 10 µM Nutlin-3a or DMSO control, and cultured in HPLM. Densitometric quantification relative to siControl DMSO samples and actin levels. D Nutrient-dependent phase model of p53-RFX7-mediated mTORC1 inhibition. The low mTORC1 activity we observed in U2OS cells cultured with physiological nutrient access likely resembles rather normal/medium activity levels, whereas the elevated mTORC1 activity in cells cultured with excess nutrients reflects high or hyper-activity. Both p53 and RFX7 are required to balance mTORC1 activity. Uninduced p53 and RFX7 are required to limit mTORC1 activity under physiological nutrient abundance, but are insufficient to keep high or hyper-activated mTORC1 in check. The activation of p53-RFX7 signaling enables p53 and RFX7 to reduce the activity of hyper-active mTORC1.
