MTORC1 functions as a transcriptional regulator of autophagy by preventing nuclear transport of TFEB

Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD USA.
Autophagy (Impact Factor: 11.42). 06/2012; 8(6):903-14. DOI: 10.4161/auto.19653
Source: PubMed

ABSTRACT The mammalian target of rapamycin (MTOR) protein kinase complex is a key component of a pathway that regulates cell growth and proliferation in response to energy levels, hypoxia, nutrients and insulin. Inhibition of MTORC1 strongly induces autophagy by regulating the activity of the ULK protein kinase complex that is required for the formation of autophagosomes. However, the participation of MTORC1 in the expression of autophagy genes has not been characterized. Here we show that MTORC1 regulates nuclear localization and activity of the transcription factor EB (TFEB), a member of the bHLH leucine-zipper family of transcription factors that drives expression of autophagy and lysosomal genes. Under normal nutrient conditions, TFEB is phosphorylated in Ser211 in an MTORC1-dependent manner. This phosphorylation promotes association of TFEB with members of the YWHA (14-3-3) family of proteins and retention of the transcription factor in the cytosol. Pharmacological or genetic inhibition of MTORC1 causes dissociation of the TFEB/YWHA complex and rapid transport of TFEB to the nucleus where it increases transcription of multiple genes implicated in autophagy and lysosomal function. Active TFEB also associates with late endosomal/lysosomal membranes through interaction with the LAMTOR/RRAG/MTORC1 complex. Our results unveil a novel role for MTORC1 in the maintenance of cellular homeostasis by regulating autophagy at the transcriptional level.

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    • "In comparison to the partial rescue of muscle area achieved by other modifiers, such as mblC, DIAP1 overexpression or Atg gene silencing, the recovery obtained upon mTOR overexpression was complete. The fact that mTOR overexpression in model flies dramatically enhanced muscle area recovery and apoptosis activity could be due to the fact that mTOR, besides being a negative regulator of autophagy, regulates protein synthesis driving cell growth and proliferation (Martina et al., 2012). Consequently, the dramatic recovery of muscle area that we observed in model flies could be a combination of the activation of protein synthesis induced by mTOR overexpression and the negative regulation of autophagy. "
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    Journal of Cell Science 06/2015; DOI:10.1242/jcs.173807 · 5.33 Impact Factor
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    • "n to control the transcription of autophagy and lysosomal biogenesis genes in response to nutritional stress ( Settembre and Ballabio , 2011 ) . Upstream negative regulation by the kinases mTORC1 and ERK2 maintains TFEB inactive until intracellular amino acids become depleted ( Settembre et al . , 2011 , 2012 ) or lysosomal function is disrupted ( Martina et al . , 2012 ; Roczniak - Ferguson et al . , 2012 ; Settembre et al . , 2012 ) . Furthermore , we and others have shown that TFEB controls lipid store mobilization under conditions of nutritional deprivation , a function that is conserved between mammals and nematodes ( Cuervo , 2013 ; O ' Rourke and Ruvkun , 2013 ; Settembre et al . , 2013 ) . Due "
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