1
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Zwakenberg S, Westland D, van Es RM, Rehmann H, Anink J, Ciapaite J, Bosma M, Stelloo E, Liv N, Sobrevals Alcaraz P, Verhoeven-Duif NM, Jans JJM, Vos HR, Aronica E, Zwartkruis FJT. mTORC1 restricts TFE3 activity by auto-regulating its presence on lysosomes. Mol Cell 2024; 84:4368-4384.e6. [PMID: 39486419 DOI: 10.1016/j.molcel.2024.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 07/10/2024] [Accepted: 10/07/2024] [Indexed: 11/04/2024]
Abstract
To stimulate cell growth, the protein kinase complex mTORC1 requires intracellular amino acids for activation. Amino-acid sufficiency is relayed to mTORC1 by Rag GTPases on lysosomes, where growth factor signaling enhances mTORC1 activity via the GTPase Rheb. In the absence of amino acids, GATOR1 inactivates the Rags, resulting in lysosomal detachment and inactivation of mTORC1. We demonstrate that in human cells, the release of mTORC1 from lysosomes depends on its kinase activity. In accordance with a negative feedback mechanism, activated mTOR mutants display low lysosome occupancy, causing hypo-phosphorylation and nuclear localization of the lysosomal substrate TFE3. Surprisingly, mTORC1 activated by Rheb does not increase the cytoplasmic/lysosomal ratio of mTORC1, indicating the existence of mTORC1 pools with distinct substrate specificity. Dysregulation of either pool results in aberrant TFE3 activity and may explain nuclear accumulation of TFE3 in epileptogenic malformations in focal cortical dysplasia type II (FCD II) and tuberous sclerosis (TSC).
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Affiliation(s)
- Susan Zwakenberg
- Center for Molecular Medicine, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands; Oncode Institute, Utrecht, the Netherlands
| | - Denise Westland
- Center for Molecular Medicine, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Robert M van Es
- Center for Molecular Medicine, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands; Oncode Institute, Utrecht, the Netherlands
| | - Holger Rehmann
- Department of Energy and Life Science, Flensburg University of Applied Sciences, Flensburg, Germany
| | - Jasper Anink
- Department of (Neuro)Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Jolita Ciapaite
- Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Marjolein Bosma
- Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Ellen Stelloo
- Center for Molecular Medicine, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Nalan Liv
- Center for Molecular Medicine, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Paula Sobrevals Alcaraz
- Center for Molecular Medicine, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands; Oncode Institute, Utrecht, the Netherlands
| | - Nanda M Verhoeven-Duif
- Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Judith J M Jans
- Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Harmjan R Vos
- Center for Molecular Medicine, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands; Oncode Institute, Utrecht, the Netherlands
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, the Netherlands; Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, the Netherlands
| | - Fried J T Zwartkruis
- Center for Molecular Medicine, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands; Oncode Institute, Utrecht, the Netherlands.
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2
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Acharya A, Demetriades C. mTORC1 activity licenses its own release from the lysosomal surface. Mol Cell 2024; 84:4385-4400.e7. [PMID: 39486418 DOI: 10.1016/j.molcel.2024.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 08/17/2024] [Accepted: 10/07/2024] [Indexed: 11/04/2024]
Abstract
Nutrient signaling converges on mTORC1, which, in turn, orchestrates a physiological cellular response. A key determinant of mTORC1 activity is its shuttling between the lysosomal surface and the cytoplasm, with nutrients promoting its recruitment to lysosomes by the Rag GTPases. Active mTORC1 regulates various cellular functions by phosphorylating distinct substrates at different subcellular locations. Importantly, how mTORC1 that is activated on lysosomes is released to meet its non-lysosomal targets and whether mTORC1 activity itself impacts its localization remain unclear. Here, we show that, in human cells, mTORC1 inhibition prevents its release from lysosomes, even under starvation conditions, which is accompanied by elevated and sustained phosphorylation of its lysosomal substrate TFEB. Mechanistically, "inactive" mTORC1 causes persistent Rag activation, underlining its release as another process actively mediated via the Rags. In sum, we describe a mechanism by which mTORC1 controls its own localization, likely to prevent futile cycling on and off lysosomes.
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Affiliation(s)
- Aishwarya Acharya
- Max Planck Institute for Biology of Ageing (MPI-AGE), 50931 Cologne, Germany; Cologne Graduate School of Ageing Research (CGA), 50931 Cologne, Germany
| | - Constantinos Demetriades
- Max Planck Institute for Biology of Ageing (MPI-AGE), 50931 Cologne, Germany; Cologne Graduate School of Ageing Research (CGA), 50931 Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
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3
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Hosios AM, Wilkinson ME, McNamara MC, Kalafut KC, Torrence ME, Asara JM, Manning BD. mTORC1 regulates a lysosome-dependent adaptive shift in intracellular lipid species. Nat Metab 2022; 4:1792-1811. [PMID: 36536136 PMCID: PMC9799240 DOI: 10.1038/s42255-022-00706-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 11/03/2022] [Indexed: 12/24/2022]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) senses and relays environmental signals from growth factors and nutrients to metabolic networks and adaptive cellular systems to control the synthesis and breakdown of macromolecules; however, beyond inducing de novo lipid synthesis, the role of mTORC1 in controlling cellular lipid content remains poorly understood. Here we show that inhibition of mTORC1 via small molecule inhibitors or nutrient deprivation leads to the accumulation of intracellular triglycerides in both cultured cells and a mouse tumor model. The elevated triglyceride pool following mTORC1 inhibition stems from the lysosome-dependent, but autophagy-independent, hydrolysis of phospholipid fatty acids. The liberated fatty acids are available for either triglyceride synthesis or β-oxidation. Distinct from the established role of mTORC1 activation in promoting de novo lipid synthesis, our data indicate that mTORC1 inhibition triggers membrane phospholipid trafficking to the lysosome for catabolism and an adaptive shift in the use of constituent fatty acids for storage or energy production.
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Affiliation(s)
- Aaron M Hosios
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Meghan E Wilkinson
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Molly C McNamara
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Krystle C Kalafut
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Margaret E Torrence
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - John M Asara
- Mass Spectrometry Core, Beth Israel Deaconess Medical Center, Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Brendan D Manning
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
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4
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Asrani K, Woo J, Mendes AA, Schaffer E, Vidotto T, Villanueva CR, Feng K, Oliveira L, Murali S, Liu HB, Salles DC, Lam B, Argani P, Lotan TL. An mTORC1-mediated negative feedback loop constrains amino acid-induced FLCN-Rag activation in renal cells with TSC2 loss. Nat Commun 2022; 13:6808. [PMID: 36357396 PMCID: PMC9649702 DOI: 10.1038/s41467-022-34617-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/01/2022] [Indexed: 11/12/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) integrates inputs from growth factors and nutrients, but how mTORC1 autoregulates its activity remains unclear. The MiT/TFE transcription factors are phosphorylated and inactivated by mTORC1 following lysosomal recruitment by RagC/D GTPases in response to amino acid stimulation. We find that starvation-induced lysosomal localization of the RagC/D GAP complex, FLCN:FNIP2, is markedly impaired in a mTORC1-sensitive manner in renal cells with TSC2 loss, resulting in unexpected TFEB hypophosphorylation and activation upon feeding. TFEB phosphorylation in TSC2-null renal cells is partially restored by destabilization of the lysosomal folliculin complex (LFC) induced by FLCN mutants and is fully rescued by forced lysosomal localization of the FLCN:FNIP2 dimer. Our data indicate that a negative feedback loop constrains amino acid-induced, FLCN:FNIP2-mediated RagC activity in renal cells with constitutive mTORC1 signaling, and the resulting MiT/TFE hyperactivation may drive oncogenesis with loss of the TSC2 tumor suppressor.
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Affiliation(s)
- Kaushal Asrani
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Juhyung Woo
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Adrianna A. Mendes
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Ethan Schaffer
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Thiago Vidotto
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Clarence Rachel Villanueva
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Kewen Feng
- grid.21107.350000 0001 2171 9311Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Lia Oliveira
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Sanjana Murali
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Hans B. Liu
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Daniela C. Salles
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Brandon Lam
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Pedram Argani
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Tamara L. Lotan
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA ,grid.21107.350000 0001 2171 9311Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD USA ,grid.21107.350000 0001 2171 9311Department of Urology, Johns Hopkins University School of Medicine, Baltimore, MD USA
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5
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Hu G, Li G, Huang D, Zou Y, Yuan X, Ritter JK, Li N, Li PL. Renomedullary exosomes produce antihypertensive effects in reversible two-kidney one-clip renovascular hypertensive mice. Biochem Pharmacol 2022; 204:115238. [PMID: 36055382 PMCID: PMC10777442 DOI: 10.1016/j.bcp.2022.115238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 11/02/2022]
Abstract
The rapid fall in blood pressure following unclipping of the stenotic renal artery in the Goldblatt two-kidney one-clip (2K1C) model of renovascular hypertension is proposed to be due to release of renomedullary vasodepressor lipids, but the mechanism has remained unclear. In this study, we hypothesized that the hypotensive response to unclipping is mediated by exosomes released from the renal medulla. In male C57BL6/J mice made hypertensive by the 2K1C surgery, unclipping of the renal artery after 10 days decreased mean arterial pressure (MAP) by 23 mmHg one hr after unclipping. This effect was accompanied by a 556% increase in the concentration of exosomes in plasma as observed by nanoparticle tracking analysis. Immunohistochemical analysis of exosome markers, CD63 and AnnexinII, showed increased staining in interstitial cells of the inner medulla of stenotic but not contralateral control kidney of clipped 2K1C mice. Treatment with rapamycin, an inducer of exosome release, blunted the hypertensive response to clipping, whereas GW-4869, an exosome biosynthesis inhibitor, prevented both the clipping-induced increase in inner medullary exosome marker staining and the unclipping-induced fall in MAP. Plasma exosomes isolated from unclipped 2K1C mice showed elevated neutral lipid content compared to sham mouse exosomes by flow cytometric analysis after Nile red staining. Exosomes from 2K1C but not sham control mice exerted potent MAP-lowering and diuretic-natriuretic effects in both 2K1C and angiotensin II-infused hypertensive mice. These results are consistent with increased renomedullary synthesis and release of exosomes with elevated antihypertensive neutral lipids in response to increased renal perfusion pressure.
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Affiliation(s)
- Gaizun Hu
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond VA23298, United States
| | - Guangbi Li
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond VA23298, United States
| | - Dandan Huang
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond VA23298, United States
| | - Yao Zou
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond VA23298, United States
| | - Xinxu Yuan
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond VA23298, United States
| | - Joseph K Ritter
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond VA23298, United States
| | - Ningjun Li
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond VA23298, United States
| | - Pin-Lan Li
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond VA23298, United States.
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6
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Hirst J, Hesketh GG, Gingras AC, Robinson MS. Rag GTPases and phosphatidylinositol 3-phosphate mediate recruitment of the AP-5/SPG11/SPG15 complex. J Cell Biol 2021; 220:211690. [PMID: 33464297 PMCID: PMC7814351 DOI: 10.1083/jcb.202002075] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 05/21/2020] [Accepted: 12/02/2020] [Indexed: 12/31/2022] Open
Abstract
Adaptor protein complex 5 (AP-5) and its partners, SPG11 and SPG15, are recruited onto late endosomes and lysosomes. Here we show that recruitment of AP-5/SPG11/SPG15 is enhanced in starved cells and occurs by coincidence detection, requiring both phosphatidylinositol 3-phosphate (PI3P) and Rag GTPases. PI3P binding is via the SPG15 FYVE domain, which, on its own, localizes to early endosomes. GDP-locked RagC promotes recruitment of AP-5/SPG11/SPG15, while GTP-locked RagA prevents its recruitment. Our results uncover an interplay between AP-5/SPG11/SPG15 and the mTORC1 pathway and help to explain the phenotype of AP-5/SPG11/SPG15 deficiency in patients, including the defect in autophagic lysosome reformation.
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Affiliation(s)
- Jennifer Hirst
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK,Jennifer Hirst:
| | - Geoffrey G. Hesketh
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Margaret S. Robinson
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK,Correspondence to Margaret S. Robinson:
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7
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Iffland PH, Barnes AE, Baybis M, Crino PB. Dynamic analysis of 4E-BP1 phosphorylation in neurons with Tsc2 or Depdc5 knockout. Exp Neurol 2020; 334:113432. [PMID: 32781001 DOI: 10.1016/j.expneurol.2020.113432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 07/13/2020] [Accepted: 08/04/2020] [Indexed: 12/15/2022]
Abstract
TSC1 or TSC2 mutations cause Tuberous Sclerosis Complex (TSC), and lead to mechanistic target of rapamycin (mTOR) hyperactivation evidenced by hyperphosphorylation of ribosomal S6 protein and 4-elongation factor binding protein 1 (4E-BP1). Amino acid (AA) levels modulate mTOR-dependent S6 and 4E-BP1 phosphorylation in non-neural cells, but this has not been comprehensively investigated in neurons. The effects of AA levels on mTOR signaling and S6 and 4E-BP1 phosphorylation were analyzed in Tsc2 and Depdc5 (a distinct mTOR regulatory gene associated with epilepsy) CRISPR-edited Neuro2a (N2a) cells and differentiated neurons. Tsc2 or Depdc5 knockout (KO) led to S6 and 4E-BP1 hyperphosphorylation and cell soma enlargement, but while Tsc2 KO N2a cells exhibited reduced S6 phosphorylation (Ser240/244) and cell soma size after incubation in AA free (AAF) media, Depdc5 KO cells did not. Using a CFP/YFP FRET-biosensor coupled to 4E-BP1, we assayed 4E-BP1 phosphorylation in living N2a cells and differentiated neurons following Tsc2 or Depdc5 KO. AAF conditions reduced 4E-BP1 phosphorylation in Tsc2 KO N2a cells but had no effect in Depdc5 KO cells. Rapamycin blocked S6 protein phosphorylation but had no effect on 4E-BP1 phosphorylation, following either Tsc2 or Depdc5 KO. Confocal imaging demonstrated that AAF media promoted movement of mTOR off the lysosome, functionally inactivating mTOR, in Tsc2 KO but not Depdc5 KO cells, demonstrating that AA levels modulate lysosomal mTOR localization and account, in part, for differential effects of AAF conditions following Tsc2 versus Depdc5 KO. AA levels and rapamycin differentially modulate S6 and 4E-BP1 phosphorylation and mTOR lysosomal localization in neurons following Tsc2 KO versus Depdc5 KO. Neuronal mTOR signaling in mTOR-associated epilepsies may have distinct responses to mTOR inhibitors and to levels of cellular amino acids.
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Affiliation(s)
- Philip H Iffland
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - Allan E Barnes
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - Marianna Baybis
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - Peter B Crino
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, United States of America.
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8
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Hong Z, Pedersen NM, Wang L, Torgersen ML, Stenmark H, Raiborg C. PtdIns3P controls mTORC1 signaling through lysosomal positioning. J Cell Biol 2017; 216:4217-4233. [PMID: 29030394 PMCID: PMC5716264 DOI: 10.1083/jcb.201611073] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 07/04/2017] [Accepted: 08/21/2017] [Indexed: 01/06/2023] Open
Abstract
mTORC1 is activated by lysosome positioning and by amino acid–induced phosphatidylinositol 3-phosphate (PtdIns3P). Hong et al. show that amino acids stimulate recruitment of the PtdIns3P-binding protein FYCO1 to lysosomes and promote contacts between FYCO1 lysosomes and ER that contains the PtdIns3P effector Protrudin, mediating lysosome translocation and facilitating mTORC1 activation. The mechanistic target of rapamycin complex 1 (mTORC1) is a protein kinase complex that localizes to lysosomes to up-regulate anabolic processes and down-regulate autophagy. Although mTORC1 is known to be activated by lysosome positioning and by amino acid–stimulated production of phosphatidylinositol 3-phosphate (PtdIns3P) by the lipid kinase VPS34/PIK3C3, the mechanisms have been elusive. Here we present results that connect these seemingly unrelated pathways for mTORC1 activation. Amino acids stimulate recruitment of the PtdIns3P-binding protein FYCO1 to lysosomes and promote contacts between FYCO1 lysosomes and endoplasmic reticulum that contain the PtdIns3P effector Protrudin. Upon overexpression of Protrudin and FYCO1, mTORC1–positive lysosomes translocate to the cell periphery, thereby facilitating mTORC1 activation. This requires the ability of Protrudin to bind PtdIns3P. Conversely, upon VPS34 inhibition, or depletion of Protrudin or FYCO1, mTORC1-positive lysosomes cluster perinuclearly, accompanied by reduced mTORC1 activity under nutrient-rich conditions. Consequently, the transcription factor EB enters the nucleus, and autophagy is up-regulated. We conclude that PtdIns3P-dependent lysosome translocation to the cell periphery promotes mTORC1 activation.
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Affiliation(s)
- Zhi Hong
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, Oslo, Norway.,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo, Norway
| | - Nina Marie Pedersen
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, Oslo, Norway.,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo, Norway
| | - Ling Wang
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, Oslo, Norway.,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo, Norway
| | - Maria Lyngaas Torgersen
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, Oslo, Norway.,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo, Norway
| | - Harald Stenmark
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, Oslo, Norway.,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo, Norway
| | - Camilla Raiborg
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, Oslo, Norway .,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo, Norway
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9
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Vial ML, Zencak D, Grkovic T, Gorse AD, Mackay-Sim A, Mellick GD, Wood SA, Quinn RJ. A Grand Challenge. 2. Phenotypic Profiling of a Natural Product Library on Parkinson's Patient-Derived Cells. JOURNAL OF NATURAL PRODUCTS 2016; 79:1982-1989. [PMID: 27447544 DOI: 10.1021/acs.jnatprod.6b00258] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Harnessing the inherent biological relevance of natural products requires a method for the recognition of biological effects that may subsequently lead to the discovery of particular targets. An unbiased multidimensional profiling method was used to examine the activities of natural products on primary cells derived from a Parkinson's disease patient. The biological signature of 482 natural products was examined using multiparametric analysis to investigate known cellular pathways and organelles implicated in Parkinson's disease such as mitochondria, lysosomes, endosomes, apoptosis, and autophagy. By targeting several cell components simultaneously the chance of finding a phenotype was increased. The phenotypes were then clustered using an uncentered correlation. The multidimensional phenotypic screening showed that all natural products, in our screening set, were biologically relevant compounds as determined by an observed phenotypic effect. Multidimensional phenotypic screening can predict the cellular function and subcellular site of activity of new compounds, while the cluster analysis provides correlation with compounds with known mechanisms of action. This study reinforces the value of natural products as biologically relevant compounds.
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Affiliation(s)
- Marie-Laure Vial
- Eskitis Institute for Drug Discovery, Griffith University , Brisbane, QLD 4111, Australia
| | - Dusan Zencak
- Eskitis Institute for Drug Discovery, Griffith University , Brisbane, QLD 4111, Australia
| | - Tanja Grkovic
- Eskitis Institute for Drug Discovery, Griffith University , Brisbane, QLD 4111, Australia
| | - Alain-Dominique Gorse
- QFAB Bioinformatics, Institute for Molecular Bioscience, The University of Queensland , St Lucia, QLD 4072, Australia
| | - Alan Mackay-Sim
- Eskitis Institute for Drug Discovery, Griffith University , Brisbane, QLD 4111, Australia
| | - George D Mellick
- Eskitis Institute for Drug Discovery, Griffith University , Brisbane, QLD 4111, Australia
| | - Stephen A Wood
- Eskitis Institute for Drug Discovery, Griffith University , Brisbane, QLD 4111, Australia
| | - Ronald J Quinn
- Eskitis Institute for Drug Discovery, Griffith University , Brisbane, QLD 4111, Australia
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10
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Ivanova EA, van den Heuvel LP, Elmonem MA, De Smedt H, Missiaen L, Pastore A, Mekahli D, Bultynck G, Levtchenko EN. Altered mTOR signalling in nephropathic cystinosis. J Inherit Metab Dis 2016; 39:457-464. [PMID: 26909499 DOI: 10.1007/s10545-016-9919-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 01/22/2016] [Accepted: 02/02/2016] [Indexed: 11/27/2022]
Abstract
Lysosomes play a central role in regulating autophagy via activation of mammalian target of rapamycin complex 1 (mTORC1). We examined mTORC1 signalling in the lysosomal storage disease nephropathic cystinosis (MIM 219800), in which accumulation of autophagy markers has been previously demonstrated. Cystinosis is caused by mutations in the lysosomal cystine transporter cystinosin and initially affects kidney proximal tubules causing renal Fanconi syndrome, followed by a gradual development of end-stage renal disease and extrarenal complications. Using proximal tubular kidney cells obtained from healthy donors and from cystinotic patients, we demonstrate that cystinosin deficiency is associated with a perturbed mTORC1 signalling, delayed reactivation of mTORC1 after starvation and abnormal lysosomal retention of mTOR during starvation. These effects could not be reversed by treatment with cystine-depleting drug cysteamine. Altered mTORC1 signalling can contribute to the development of proximal tubular dysfunction in cystinosis and points to new possibilities in therapeutic intervention through modulation of mTORC-dependent signalling cascades.
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Affiliation(s)
- Ekaterina A Ivanova
- Department of Growth and Regeneration, KU Leuven and University Hospitals Leuven, UZ Herestraat 49, 3000, Leuven, Belgium
| | - Lambertus P van den Heuvel
- Department of Growth and Regeneration, KU Leuven and University Hospitals Leuven, UZ Herestraat 49, 3000, Leuven, Belgium
- Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mohamed A Elmonem
- Department of Growth and Regeneration, KU Leuven and University Hospitals Leuven, UZ Herestraat 49, 3000, Leuven, Belgium
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Humbert De Smedt
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Ludwig Missiaen
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Anna Pastore
- Laboratory of Proteomics and Metabolomics, Children's Hospital and Research Institute "Bambino Gesù" IRCCS, Rome, Italy
| | - Djalila Mekahli
- Department of Growth and Regeneration, KU Leuven and University Hospitals Leuven, UZ Herestraat 49, 3000, Leuven, Belgium
| | - Greet Bultynck
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Elena N Levtchenko
- Department of Growth and Regeneration, KU Leuven and University Hospitals Leuven, UZ Herestraat 49, 3000, Leuven, Belgium.
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11
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Cortez C, Real F, Yoshida N. Lysosome biogenesis/scattering increases host cell susceptibility to invasion by Trypanosoma cruzi metacyclic forms and resistance to tissue culture trypomastigotes. Cell Microbiol 2016; 18:748-60. [PMID: 26572924 PMCID: PMC5064668 DOI: 10.1111/cmi.12548] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/08/2015] [Accepted: 11/11/2015] [Indexed: 01/11/2023]
Abstract
A fundamental question to be clarified concerning the host cell invasion by Trypanosoma cruzi is whether the insect-borne and mammalian-stage parasites use similar mechanisms for invasion. To address that question, we analysed the cell invasion capacity of metacyclic trypomastigotes (MT) and tissue culture trypomastigotes (TCT) under diverse conditions. Incubation of parasites for 1 h with HeLa cells in nutrient-deprived medium, a condition that triggered lysosome biogenesis and scattering, increased MT invasion and reduced TCT entry into cells. Sucrose-induced lysosome biogenesis increased HeLa cell susceptibility to MT and resistance to TCT. Treatment of cells with rapamycin, which inhibits mammalian target of rapamycin (mTOR), induced perinuclear lysosome accumulation and reduced MT invasion while augmenting TCT invasion. Metacylic trypomastigotes, but not TCT, induced mTOR dephosphorylation and the nuclear translocation of transcription factor EB (TFEB), a mTOR-associated lysosome biogenesis regulator. Lysosome biogenesis/scattering was stimulated upon HeLa cell interaction with MT but not with TCT. Recently, internalized MT, but not TCT, were surrounded by colocalized lysosome marker LAMP2 and mTOR. The recombinant gp82 protein, the MT-specific surface molecule that mediates invasion, induced mTOR dephosphorylation, nuclear TFEB translocation and lysosome biogenesis/scattering. Taken together, our data clearly indicate that MT invasion is mainly lysosome-dependent, whereas TCT entry is predominantly lysosome-independent.
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Affiliation(s)
- Cristian Cortez
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, R. Pedro de Toledo, 669-6° andar, 04039-032, São Paulo, SP, Brazil
| | - Fernando Real
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, R. Pedro de Toledo, 669-6° andar, 04039-032, São Paulo, SP, Brazil
| | - Nobuko Yoshida
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, R. Pedro de Toledo, 669-6° andar, 04039-032, São Paulo, SP, Brazil
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12
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Zhou X, Clister TL, Lowry PR, Seldin MM, Wong GW, Zhang J. Dynamic Visualization of mTORC1 Activity in Living Cells. Cell Rep 2015; 10:1767-1777. [PMID: 25772363 DOI: 10.1016/j.celrep.2015.02.031] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 01/15/2015] [Accepted: 02/09/2015] [Indexed: 12/18/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) senses diverse signals to regulate cell growth and metabolism. It has become increasingly clear that mTORC1 activity is regulated in time and space inside the cell, but direct interrogation of such spatiotemporal regulation is challenging. Here, we describe a genetically encoded mTORC1 activity reporter (TORCAR) that exhibits a change in FRET in response to phosphorylation by mTORC1. Co-imaging mTORC1 activity and calcium dynamics revealed that a growth-factor-induced calcium transient contributes to mTORC1 activity. Dynamic activity maps generated with the use of subcellularly targeted TORCAR uncovered mTORC1 activity not only in cytosol and at the lysosome but also in the nucleus and at the plasma membrane. Furthermore, a wide distribution of activities was observed upon growth factor stimulation, whereas leucine ester, an amino acid surrogate, induces more compartmentalized activities at the lysosome and in the nucleus. Thus, mTORC1 activities are spatiotemporally regulated in a signal-specific manner.
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Affiliation(s)
- Xin Zhou
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Terri L Clister
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Pamela R Lowry
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Marcus M Seldin
- Department of Physiology and Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - G William Wong
- Department of Physiology and Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jin Zhang
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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13
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Yamamura T, Ohsaki Y, Suzuki M, Shinohara Y, Tatematsu T, Cheng J, Okada M, Ohmiya N, Hirooka Y, Goto H, Fujimoto T. Inhibition of Niemann-Pick-type C1-like1 by ezetimibe activates autophagy in human hepatocytes and reduces mutant α1-antitrypsin Z deposition. Hepatology 2014; 59:1591-9. [PMID: 24214142 DOI: 10.1002/hep.26930] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 11/04/2013] [Indexed: 12/16/2022]
Abstract
UNLABELLED Autophagy can degrade aggregate-prone proteins, but excessive autophagy can have adverse effects. It would be beneficial if autophagy could be enhanced in a cell type-specific manner, but this has been difficult because the basic mechanism of autophagy is common. In the present study we found that inhibition of Niemann-Pick-type C1-like 1 (NPC1L1) by ezetimibe activates autophagy only in hepatocytes and small intestinal epithelia, but not in other cells. Ezetimibe induced accumulation of free cholesterol in the late endosome/lysosome and increased partitioning of a Ragulator component, LAMTOR1, in rafts. The latter change led to down-regulation of mammalian target of rapamycin (mTOR)C1 activity by decreasing mTOR recruitment to the late endosome/lysosome and activated autophagy. A primary effect of ezetimibe was found to be a decrease of free cholesterol in the plasma membrane, because all the results caused by ezetimibe were suppressed by supplementation of cholesterol as a methyl-β-cyclodextrin complex. By enhancing autophagy in human primary hepatocytes with ezetimibe, insoluble mutant α1-antitrypsin Z was reduced significantly. CONCLUSION Inhibition of NPC1L1 by ezetimibe activates autophagy in human hepatocytes by modulating cholesterol homeostasis. Ezetimibe may be used to ameliorate liver degeneration in α1-antitrypsin deficiency.
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Affiliation(s)
- Takeshi Yamamura
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan; Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
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14
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Zhou J, Tan SH, Nicolas V, Bauvy C, Yang ND, Zhang J, Xue Y, Codogno P, Shen HM. Activation of lysosomal function in the course of autophagy via mTORC1 suppression and autophagosome-lysosome fusion. Cell Res 2013; 23:508-23. [PMID: 23337583 PMCID: PMC3616426 DOI: 10.1038/cr.2013.11] [Citation(s) in RCA: 330] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 11/27/2012] [Accepted: 11/30/2012] [Indexed: 12/11/2022] Open
Abstract
Lysosome is a key subcellular organelle in the execution of the autophagic process and at present little is known whether lysosomal function is controlled in the process of autophagy. In this study, we first found that suppression of mammalian target of rapamycin (mTOR) activity by starvation or two mTOR catalytic inhibitors (PP242 and Torin1), but not by an allosteric inhibitor (rapamycin), leads to activation of lysosomal function. Second, we provided evidence that activation of lysosomal function is associated with the suppression of mTOR complex 1 (mTORC1), but not mTORC2, and the mTORC1 localization to lysosomes is not directly correlated to its regulatory role in lysosomal function. Third, we examined the involvement of transcription factor EB (TFEB) and demonstrated that TFEB activation following mTORC1 suppression is necessary but not sufficient for lysosomal activation. Finally, Atg5 or Atg7 deletion or blockage of the autophagosome-lysosome fusion process effectively diminished lysosomal activation, suggesting that lysosomal activation occurring in the course of autophagy is dependent on autophagosome-lysosome fusion. Taken together, this study demonstrates that in the course of autophagy, lysosomal function is upregulated via a dual mechanism involving mTORC1 suppression and autophagosome-lysosome fusion.
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Affiliation(s)
- Jing Zhou
- Department of Physiology, Yong Loo Lin School of Medicine and Saw Swee Hock School of Public Health, National University of Singapore, Singapore 117597
| | - Shi-Hao Tan
- Department of Physiology, Yong Loo Lin School of Medicine and Saw Swee Hock School of Public Health, National University of Singapore, Singapore 117597
- NUS Graduate School for Integrative Sciences and Engineering National University of Singapore, Singapore 117597
| | - Valérie Nicolas
- Microscopy Facility-IFR-141-IPSIT, rue JB Clément, 92296 Châtenay-Malabry, France
- University Paris-Sud, Orsay, France
| | - Chantal Bauvy
- University Paris-Sud, Orsay, France
- INSERM U984, 92296 Châtenay-Malabry, France
| | - Nai-Di Yang
- Department of Physiology, Yong Loo Lin School of Medicine and Saw Swee Hock School of Public Health, National University of Singapore, Singapore 117597
| | - Jianbin Zhang
- Department of Physiology, Yong Loo Lin School of Medicine and Saw Swee Hock School of Public Health, National University of Singapore, Singapore 117597
| | - Yuan Xue
- Reed College, Portland, OR 97202, USA
| | - Patrice Codogno
- University Paris-Sud, Orsay, France
- INSERM U984, 92296 Châtenay-Malabry, France
| | - Han-Ming Shen
- Department of Physiology, Yong Loo Lin School of Medicine and Saw Swee Hock School of Public Health, National University of Singapore, Singapore 117597
- NUS Graduate School for Integrative Sciences and Engineering National University of Singapore, Singapore 117597
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15
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16
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Roczniak-Ferguson A, Petit CS, Froehlich F, Qian S, Ky J, Angarola B, Walther TC, Ferguson SM. The transcription factor TFEB links mTORC1 signaling to transcriptional control of lysosome homeostasis. Sci Signal 2012; 5:ra42. [PMID: 22692423 DOI: 10.1126/scisignal.2002790] [Citation(s) in RCA: 1004] [Impact Index Per Article: 77.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lysosomes are the major cellular site for clearance of defective organelles and digestion of internalized material. Demand on lysosomal capacity can vary greatly, and lysosomal function must be adjusted to maintain cellular homeostasis. Here, we identified an interaction between the lysosome-localized mechanistic target of rapamycin complex 1 (mTORC1) and the transcription factor TFEB (transcription factor EB), which promotes lysosome biogenesis. When lysosomal activity was adequate, mTOR-dependent phosphorylation of TFEB on Ser(211) triggered the binding of 14-3-3 proteins to TFEB, resulting in retention of the transcription factor in the cytoplasm. Inhibition of lysosomal function reduced the mTOR-dependent phosphorylation of TFEB, resulting in diminished interactions between TFEB and 14-3-3 proteins and the translocation of TFEB into the nucleus, where it could stimulate genes involved in lysosomal biogenesis. These results identify TFEB as a target of mTOR and suggest a mechanism for matching the transcriptional regulation of genes encoding proteins of autophagosomes and lysosomes to cellular need. The closely related transcription factors MITF (microphthalmia transcription factor) and TFE3 (transcription factor E3) also localized to lysosomes and accumulated in the nucleus when lysosome function was inhibited, thus broadening the range of physiological contexts under which this regulatory mechanism may prove important.
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17
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Neufeld TP. Autophagy and cell growth--the yin and yang of nutrient responses. J Cell Sci 2012; 125:2359-68. [PMID: 22649254 DOI: 10.1242/jcs.103333] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
As a response to nutrient deprivation and other cell stresses, autophagy is often induced in the context of reduced or arrested cell growth. A plethora of signaling molecules and pathways have been shown to have opposing effects on cell growth and autophagy, and results of recent functional screens on a genomic scale support the idea that these processes might represent mutually exclusive cell fates. Understanding the ways in which autophagy and cell growth relate to one another is becoming increasingly important, as new roles for autophagy in tumorigenesis and other growth-related phenomena are uncovered. This Commentary highlights recent findings that link autophagy and cell growth, and explores the mechanisms underlying these connections and their implications for cell physiology and survival. Autophagy and cell growth can inhibit one another through a variety of direct and indirect mechanisms, and can be independently regulated by common signaling pathways. The central role of the mammalian target of rapamycin (mTOR) pathway in regulating both autophagy and cell growth exemplifies one such mechanism. In addition, mTOR-independent signaling and other more direct connections between autophagy and cell growth will also be discussed.
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Affiliation(s)
- Thomas P Neufeld
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.
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18
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Yan L, Lamb RF. Amino acid sensing and regulation of mTORC1. Semin Cell Dev Biol 2012; 23:621-5. [PMID: 22342805 DOI: 10.1016/j.semcdb.2012.02.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 02/02/2012] [Indexed: 01/08/2023]
Abstract
Amino acids play fundamental roles in the cell both as the building blocks of new proteins and as metabolic precursors. To adapt to their limitation during periods of protein starvation, multiple adaptive mechanisms have evolved, including a rapid cessation of new protein synthesis, an increase in amino acid biosynthesis and transport, and autophagy. Here, we discuss what we currently know about how amino acid limitation is sensed, and how this sensing might be transmitted to mTORC1 to regulate protein synthesis and autophagy.
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Affiliation(s)
- Lijun Yan
- School of Pharmacy, Harbin University of Commerce, Harbin, 150076, PR China.
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19
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Hübner S, Efthymiadis A. Histochemistry and cell biology: the annual review 2010. Histochem Cell Biol 2011; 135:111-40. [PMID: 21279376 DOI: 10.1007/s00418-011-0781-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2011] [Indexed: 10/18/2022]
Abstract
This review summarizes recent advances in histochemistry and cell biology which complement and extend our knowledge regarding various aspects of protein functions, cell and tissue biology, employing appropriate in vivo model systems in conjunction with established and novel approaches. In this context several non-expected results and discoveries were obtained which paved the way of research into new directions. Once the reader embarks on reading this review, it quickly becomes quite obvious that the studies contribute not only to a better understanding of fundamental biological processes but also provide use-oriented aspects that can be derived therefrom.
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Affiliation(s)
- Stefan Hübner
- Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstrasse 6, 97070 Würzburg, Germany.
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