title: Plasma membrane translocation of REDD1 governed by GPCRs contributes to mTORC1 activation.
abstract: The mTORC1 kinase promotes cell growth in response to growth factors by activation of receptor tyrosine kinase. It is regulated by the cellular energy level and the availability of nutrients. mTORC1 activity is also inhibited by cellular stresses through overexpression of REDD1 (regulated in development and DNA damage responses). We report the identification of REDD1 in a fluorescent live-imaging screen aimed at discovering new proteins implicated in G-protein-coupled receptor signaling, based on translocation criteria. Using a sensitive and quantitative plasma membrane localization assay based on bioluminescent resonance energy transfer, we further show that a panel of endogenously expressed GPCRs, through a Ca(2+)/calmodulin pathway, triggers plasma membrane translocation of REDD1 but not of its homolog REDD2. REDD1 and REDD2 share a conserved mTORC1-inhibitory motif characterized at the functional and structural level and differ most in their N-termini. We show that the N-terminus of REDD1 and its mTORC1-inhibitory motif participate in the GPCR-evoked dynamic interaction of REDD1 with the plasma membrane. We further identify REDD1 as a novel effector in GPCR signaling. We show that fast activation of mTORC1 by GPCRs correlates with fast and maximal translocation of REDD1 to the plasma membrane. Overexpression of functional REDD1 leads to a reduction of mTORC1 activation by GPCRs. By contrast, depletion of endogenous REDD1 protein unleashes mTORC1 activity. Thus, translocation to the plasma membrane appears to be an inactivation mechanism of REDD1 by GPCRs, which probably act by sequestering its functional mTORC1-inhibitory motif that is necessary for plasma membrane targeting.
authors: GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 67412 Illkirch, France.
authors: Grégory
authors: G
authors: Michel
authors: Hans W D
authors: HW
authors: Matthes
authors: Muriel
authors: M
authors: Hachet-Haas
authors: Keltouma
authors: K
authors: El Baghdadi
authors: Jan
authors: J
authors: de Mey
authors: Rainer
authors: R
authors: Pepperkok
authors: Jeremy C
authors: JC
authors: Simpson
authors: Jean-Luc
authors: JL
authors: Galzi
authors: Sandra
authors: S
authors: Lecat
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D020013:Calcium Signaling; D002147:Calmodulin / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D004789:Enzyme Activation; D057809:HEK293 Cells; D006801:Humans; D000076222:Mechanistic Target of Rapamycin Complex 1; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D021382:Protein Sorting Signals; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism; D018041:Receptors, Neurokinin-2 / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002147:Calmodulin; C469991:DDIT4 protein, human; C498040:DDIT4L protein, human; D046912:Multiprotein Complexes; D021382:Protein Sorting Signals; D011506:Proteins; D018041:Receptors, Neurokinin-2; D014157:Transcription Factors; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases
keywords: Bioluminescence resonance energy transfer; Ca2+/calmodulin signaling pathway; G-protein-coupled receptors; Plasma membrane translocation; REDD1; mTOR