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Thien A, Prentzell MT, Holzwarth B, Kläsener K, Kuper I, Boehlke C, Sonntag AG, Ruf S, Maerz L, Nitschke R, Grellscheid SN, Reth M, Walz G, Baumeister R, Neumann-Haefelin E, Thedieck K. TSC1 activates TGF-β-Smad2/3 signaling in growth arrest and epithelial-to-mesenchymal transition. Dev Cell 2015; 32:617-30. [PMID: 25727005 DOI: 10.1016/j.devcel.2015.01.026] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 12/19/2014] [Accepted: 01/22/2015] [Indexed: 11/27/2022]
Abstract
The tuberous sclerosis proteins TSC1 and TSC2 are key integrators of growth factor signaling. They suppress cell growth and proliferation by acting in a heteromeric complex to inhibit the mammalian target of rapamycin complex 1 (mTORC1). In this study, we identify TSC1 as a component of the transforming growth factor β (TGF-β)-Smad2/3 pathway. Here, TSC1 functions independently of TSC2. TSC1 interacts with the TGF-β receptor complex and Smad2/3 and is required for their association with one another. TSC1 regulates TGF-β-induced Smad2/3 phosphorylation and target gene expression and controls TGF-β-induced growth arrest and epithelial-to-mesenchymal transition (EMT). Hyperactive Akt specifically activates TSC1-dependent cytostatic Smad signaling to induce growth arrest. Thus, TSC1 couples Akt activity to TGF-β-Smad2/3 signaling. This has implications for cancer treatments targeting phosphoinositide 3-kinases and Akt because they may impair tumor-suppressive cytostatic TGF-β signaling by inhibiting Akt- and TSC1-dependent Smad activation.
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Affiliation(s)
- Antje Thien
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
| | - Mirja Tamara Prentzell
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, the Netherlands
| | - Birgit Holzwarth
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Kathrin Kläsener
- Molecular Immunology (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Molecular Immunology, Max-Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Ineke Kuper
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, the Netherlands; Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129 Oldenburg, Germany
| | | | - Annika G Sonntag
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Stefanie Ruf
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, the Netherlands; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Research Training Group (RTG) 1104, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Lars Maerz
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Roland Nitschke
- BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Center for Biological Systems Analysis (ZBSA), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | | | - Michael Reth
- Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Molecular Immunology (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Molecular Immunology, Max-Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Gerd Walz
- Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Center for Biological Systems Analysis (ZBSA), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Ralf Baumeister
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Research Training Group (RTG) 1104, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Center for Biological Systems Analysis (ZBSA), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; ZBMZ Centre for Biochemistry and Molecular Cell Research (Faculty of Medicine), Albert-Ludwigs-University Freiburg, 79106 Freiburg, Germany
| | | | - Kathrin Thedieck
- Bioinformatics and Molecular Genetics (Faculty of Biology), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, the Netherlands; BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129 Oldenburg, Germany.
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Thedieck K, Holzwarth B, Prentzell MT, Boehlke C, Kläsener K, Ruf S, Sonntag AG, Maerz L, Grellscheid SN, Kremmer E, Nitschke R, Kuehn EW, Jonker JW, Groen AK, Reth M, Hall MN, Baumeister R. Inhibition of mTORC1 by astrin and stress granules prevents apoptosis in cancer cells. Cell 2013; 154:859-74. [PMID: 23953116 DOI: 10.1016/j.cell.2013.07.031] [Citation(s) in RCA: 207] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 04/03/2013] [Accepted: 07/23/2013] [Indexed: 12/21/2022]
Abstract
Mammalian target of rapamycin complex 1 (mTORC1) controls growth and survival in response to metabolic cues. Oxidative stress affects mTORC1 via inhibitory and stimulatory inputs. Whereas downregulation of TSC1-TSC2 activates mTORC1 upon oxidative stress, the molecular mechanism of mTORC1 inhibition remains unknown. Here, we identify astrin as an essential negative mTORC1 regulator in the cellular stress response. Upon stress, astrin inhibits mTORC1 association and recruits the mTORC1 component raptor to stress granules (SGs), thereby preventing mTORC1-hyperactivation-induced apoptosis. In turn, balanced mTORC1 activity enables expression of stress factors. By identifying astrin as a direct molecular link between mTORC1, SG assembly, and the stress response, we establish a unifying model of mTORC1 inhibition and activation upon stress. Importantly, we show that in cancer cells, apoptosis suppression during stress depends on astrin. Being frequently upregulated in tumors, astrin is a potential clinically relevant target to sensitize tumors to apoptosis.
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Affiliation(s)
- Kathrin Thedieck
- Faculty of Biology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany.
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