Abstract
The mTORC1 complex supports cell growth and proliferation in response to energy levels, growth factors, and nutrients. The Rag guanosine triphosphatases (GTPases) activate mTORC1 in response to amino acids by promoting its redistribution to lysosomes. In this paper, we identify a novel role for Rags in controlling activation of transcription factor EB (TFEB), a master regulator of autophagic and lysosomal gene expression. Interaction of TFEB with active Rag heterodimers promoted recruitment of TFEB to lysosomes, leading to mTORC1-dependent phosphorylation and inhibition of TFEB. The interaction of TFEB with Rags required the first 30 residues of TFEB and the switch regions of the Rags G domain. Depletion or inactivation of Rags prevented recruitment of TFEB to lysosomes, whereas expression of active Rags induced association of TFEB with lysosomal membranes. Finally, Rag GTPases bound and regulated activation of microphthalmia-associated transcription factor, suggesting a broader role for Rags in the control of gene expression. Our work provides new insight into the molecular mechanisms that link nutrient availability and TFEB localization and activation.