Dihydroxyacetone phosphate signals glucose availability to mTORC1

© 2020, The Author(s), under exclusive licence to Springer Nature Limited. The mechanistic target of rapamycin complex 1 (mTORC1) kinase regulates cell growth by setting the balance between anabolic and catabolic processes. To be active, mTORC1 requires the environmental presence of amino acids and glucose. While a mechanistic understanding of amino acid sensing by mTORC1 is emerging, how glucose activates mTORC1 remains mysterious. Here, we used metabolically engineered human cells lacking the canonical energy sensor AMP-activated protein kinase to identify glucose-derived metabolites required to activate mTORC1 independent of energetic stress. We show that mTORC1 senses a metabolite downstream of the aldolase and upstream of the GAPDH-catalysed steps of glycolysis and pinpoint dihydroxyacetone phosphate (DHAP) as the key molecule. In cells expressing a triose kinase, the synthesis of DHAP from DHA is sufficient to activate mTORC1 even in the absence of glucose. DHAP is a precursor for lipid synthesis, a process under the control of mTORC1, which provides a potential rationale for the sensing of DHAP by mTORC1

Small Molecule Enhancers of Endosome-to-Cytosol Import Augment Anti-tumor Immunity

International audienceCross-presentation of antigens by dendritic cells (DCs) is critical for initiation of anti-tumor immune responses. Yet, key steps involved in trafficking of antigens taken up by DCs remain incompletely understood. Here, we screen 700 US Food and Drug Administration (FDA)-approved drugs and identify 37 enhancers of antigen import from endolysosomes into the cytosol. To reveal their mechanism of action, we generate proteomic organellar maps of control and drug-treated DCs (focusing on two compounds, prazosin and tamoxifen). By combining organellar mapping, quantitative proteomics, and microscopy, we conclude that import enhancers undergo lysosomal trapping leading to membrane permeation and antigen release. Enhancing antigen import facilitates cross-presentation of soluble and cell-associated antigens. Systemic administration of prazosin leads to reduced growth of MC38 tumors and to a synergistic effect with checkpoint immunotherapy in a melanoma model. Thus, inefficient antigen import into the cytosol limits antigen cross-presentation, restraining the potency of anti-tumor immune responses and efficacy of checkpoint blockers

SAMTOR is an S-adenosylmethionine sensor for the mTORC1 pathway

mTOR complex 1 (mTORC1) regulates cell growth and metabolism in response to multiple environmental cues. Nutrients signal via the Rag guanosine triphosphatases (GTPases) to promote the localization of mTORC1 to the lysosomal surface, its site of activation. We identified SAMTOR, a previously uncharacterized protein, which inhibits mTORC1 signaling by interacting with GATOR1, the GTPase activating protein (GAP) for RagA/B. We found that the methyl donor S-adenosylmethionine (SAM) disrupts the SAMTOR-GATOR1 complex by binding directly to SAMTOR with a dissociation constant of approximately 7 μM. In cells, methionine starvation reduces SAM levels below this dissociation constant and promotes the association of SAMTOR with GATOR1, thereby inhibiting mTORC1 signaling in a SAMTOR-dependent fashion. Methionine-induced activation of mTORC1 requires the SAM binding capacity of SAMTOR. Thus, SAMTOR is a SAM sensor that links methionine and one-carbon metabolism to mTORC1 signaling.National Institutes of Health (U.S.) (Grant R01 CA103866)National Institutes of Health (U.S.) (Grant R37 AI47389)United States. Department of Defense (Grant W81XWH-07-0448)National Institutes of Health (U.S.) (Fellowship T32 GM007753)National Institutes of Health (U.S.) (Grant T32 GM007753)National Institutes of Health (U.S.) (Grant F30 CA210373)National Institutes of Health (U.S.) (Grant F31 GM121093-01A1)National Science Foundation (U.S.) (Grant 2016197106)Massachusetts Institute of Technology. Paul Gray UROP Fund (Grant 3143900

A histone deacetylase 3 and mitochondrial complex I axis regulates toxic formaldehyde production.

Cells produce considerable genotoxic formaldehyde from an unknown source. We carry out a genome-wide CRISPR-Cas9 genetic screen in metabolically engineered HAP1 cells that are auxotrophic for formaldehyde to find this cellular source. We identify histone deacetylase 3 (HDAC3) as a regulator of cellular formaldehyde production. HDAC3 regulation requires deacetylase activity, and a secondary genetic screen identifies several components of mitochondrial complex I as mediators of this regulation. Metabolic profiling indicates that this unexpected mitochondrial requirement for formaldehyde detoxification is separate from energy generation. HDAC3 and complex I therefore control the abundance of a ubiquitous genotoxic metabolite.Wellcome Senior Clinical Research Fellowship 215477/Z/19/Z (J.A.N.) Lister Institute Research Fellowship (J.A.N.); Addenbrooke’s Charitable Trust (J.A.N.) Medical Research Council (MRC) (K.J.P.) Cancer Research UK (CRUK) C42693/A23273 (K.J.P.) Wellcome Trust 106202/Z/14/Z (K.J.P.) Rubicon ZonMw 45219116 (E.G.) ubicon ZonMW 019.161LW.040 (D.H.E.W.H.) Trinity Hall, Cambridge University (G.B.B) Human Frontier Science Program LT000571/2019-L (G.B.B.) CRUK C60150/A23919 (M.W.) CRUK Clinician Scientist Fellowship C60150/A23919 (M.W.) CRUK C14303/A17197 and A24455 (F.G. and D.H.E.W.H.) Wellcome Trust Early-Career Award 225102/Z/22/Z (E.G.) Wellcome Investigator Award 222497/Z/21/Z (A.K.) MRC Transition Support Fellowship MR/T032413/1 (N.J.M.) NHSBT research grant WPA15-02 (N.J.M.) NIHR Cambridge BRC (N.J.M.) Wellcome Trust Institutional Strategic Support Fund 204845/Z/16/Z ( N.J.M.) Wellcome PhD Training Fellowship for Clinicians 205252/Z/16/Z (P.S.J.B)