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del Dedo JE, Segundo RLS, Vázquez-Bolado A, Sun J, García-Blanco N, Suárez MB, García P, Tricquet P, Chen JS, Dedon PC, Gould KL, Hidalgo E, Hermand D, Moreno S. The Greatwall-Endosulfine-PP2A/B55 pathway controls entry into quiescence by promoting translation of Elongator-tuneable transcripts. Res Sq 2023:rs.3.rs-3616701. [PMID: 38105947 PMCID: PMC10723533 DOI: 10.21203/rs.3.rs-3616701/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Quiescent cells require a continuous supply of proteins to maintain protein homeostasis. In fission yeast, entry into quiescence is triggered by nitrogen stress, leading to the inactivation of TORC1 and the activation of TORC2. Here, we report that the Greatwall-Endosulfine-PPA/B55 pathway connects the downregulation of TORC1 with the upregulation of TORC2, resulting in the activation of Elongator-dependent tRNA modifications essential for sustaining the translation programme during entry into quiescence. This process promotes U34 and A37 tRNA modifications at the anticodon stem loop, enhancing translation efficiency and fidelity of mRNAs enriched for AAA versus AAG lysine codons. Notably, some of these mRNAs encode inhibitors of TORC1, activators of TORC2, tRNA modifiers, and proteins necessary for telomeric and subtelomeric functions. Therefore, we propose a novel mechanism by which cells respond to nitrogen stress at the level of translation, involving a coordinated interplay between the tRNA epitranscriptome and biased codon usage.
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Affiliation(s)
- Javier Encinar del Dedo
- Instituto de Biología Funcional y Genómica, CSIC, University of Salamanca, 37007 Salamanca, Spain
| | - Rafael López-San Segundo
- Instituto de Biología Funcional y Genómica, CSIC, University of Salamanca, 37007 Salamanca, Spain
| | - Alicia Vázquez-Bolado
- Instituto de Biología Funcional y Genómica, CSIC, University of Salamanca, 37007 Salamanca, Spain
| | - Jingjing Sun
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore, Singapore
| | - Natalia García-Blanco
- Instituto de Biología Funcional y Genómica, CSIC, University of Salamanca, 37007 Salamanca, Spain
| | - M. Belén Suárez
- Instituto de Biología Funcional y Genómica, University of Salamanca, CSIC, 37007 Salamanca, Spain
- Departamento de Microbiología y Genética, University of Salamanca, 37007 Salamanca, Spain
| | - Patricia García
- Instituto de Biología Funcional y Genómica, University of Salamanca, CSIC, 37007 Salamanca, Spain
- Departamento de Microbiología y Genética, University of Salamanca, 37007 Salamanca, Spain
| | - Pauline Tricquet
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| | - Jun-Song Chen
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States
| | - Peter C. Dedon
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore, Singapore
- Department of Biological Engineering and Center for Environmental Health Science, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Kathleen L. Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States
| | - Elena Hidalgo
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Damien Hermand
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| | - Sergio Moreno
- Instituto de Biología Funcional y Genómica, CSIC, University of Salamanca, 37007 Salamanca, Spain
- Lead contact
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Biswas B, Gangwar G, Nain V, Gupta I, Thakur A, Puria R. Rapamycin and Torin2 inhibit Candida auris TOR: Insights through growth profiling, docking, and MD simulations. J Biomol Struct Dyn 2023; 41:8445-8461. [PMID: 36264093 DOI: 10.1080/07391102.2022.2134927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 10/03/2022] [Indexed: 10/24/2022]
Abstract
The fungus Candida auris is a pathogen of utmost concern due to its rapid emergence across the globe, acquired antifungal drug tolerance, thermotolerance, and ability to survive in hospital settings and preserved foods. Recent incidences of comorbidity of corona patients with its infection in hospital settings highlighted the importance of understanding the pathobiology and drug tolerance of this fungus on priority. The Target of rapamycin (TOR) is a central regulator of growth across eukaryotes with an illustrated role in fungal pathology. The role of the TOR signalling pathway in the growth of C. auris is yet to be described. In-silico, analysis revealed the presence of highly conserved Tor kinase, components of TORC, and key downstream components in C. auris. Rapamycin and Torin2, the specific inhibitors of Tor reduce the growth of C. auris. An inhibition of Tor leads to cell cycle arrest at the G1 phase with a defect in cytokinesis. Interestingly, with an insignificant difference in growth at 30 and 37 °C, a sharp decline in growth is seen with Torin2 at 37 °C. The heterogeneous response emphasizes the importance of physiology-based differential cellular response at different temperatures. In addition, the inhibition of Tor suppresses the biofilm formation. In silico studies through docking and simulations showed rapamycin and torin2 as specific inhibitors of C. auris Tor kinase (CauTor kinase) and hence can be exploited for a thorough understanding of the TOR signalling pathway in pathobiology and drug tolerance of C. auris. HIGHLIGHTSConservation of TOR signalling pathway in Candida aurisRapamycin and torin2 are specific inhibitors of Cau TorUnderstanding of the role of TOR signalling pathway through the use of inhibitors rapamycin and torin2.Heterogenous response of C. auris to torin2 at different physiological conditions.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Biswambhar Biswas
- Regional Centre for Biotechnology, 3rd Milestone Gurgaon-Faridabad Expressway, Faridabad, Haryana, India
| | - Garima Gangwar
- School of Biotechnology, Gautam Buddha University, Greater Noida, Uttar Pradesh, India
| | - Vikrant Nain
- School of Biotechnology, Gautam Buddha University, Greater Noida, Uttar Pradesh, India
| | - Ishaan Gupta
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Delhi, India
| | - Anil Thakur
- Regional Centre for Biotechnology, 3rd Milestone Gurgaon-Faridabad Expressway, Faridabad, Haryana, India
| | - Rekha Puria
- School of Biotechnology, Gautam Buddha University, Greater Noida, Uttar Pradesh, India
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Zhu XM, Li L, Bao JD, Wang JY, Liang S, Zhao LL, Huang CL, Yan JY, Cai YY, Wu XY, Dong B, Liu XH, Klionsky DJ, Lin FC. MoVast2 combined with MoVast1 regulates lipid homeostasis and autophagy in Magnaporthe oryzae. Autophagy 2023; 19:2353-2371. [PMID: 36803211 PMCID: PMC10351449 DOI: 10.1080/15548627.2023.2181739] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/22/2023] Open
Abstract
Macroautophagy/autophagy is an evolutionarily conserved biological process among eukaryotes that degrades unwanted materials such as protein aggregates, damaged mitochondria and even viruses to maintain cell survival. Our previous studies have demonstrated that MoVast1 acts as an autophagy regulator regulating autophagy, membrane tension, and sterol homeostasis in rice blast fungus. However, the detailed regulatory relationships between autophagy and VASt domain proteins remain unsolved. Here, we identified another VASt domain-containing protein, MoVast2, and further uncovered the regulatory mechanism of MoVast2 in M. oryzae. MoVast2 interacted with MoVast1 and MoAtg8, and colocalized at the PAS and deletion of MoVAST2 results in inappropriate autophagy progress. Through TOR activity analysis, sterols and sphingolipid content detection, we found high sterol accumulation in the ΔMovast2 mutant, whereas this mutant showed low sphingolipids and low activity of both TORC1 and TORC2. In addition, MoVast2 colocalized with MoVast1. The localization of MoVast2 in the MoVAST1 deletion mutant was normal; however, deletion of MoVAST2 leads to mislocalization of MoVast1. Notably, the wide-target lipidomic analyses revealed significant changes in sterols and sphingolipids, the major PM components, in the ΔMovast2 mutant, which was involved in lipid metabolism and autophagic pathways. These findings confirmed that the functions of MoVast1 were regulated by MoVast2, revealing that MoVast2 combined with MoVast1 maintained lipid homeostasis and autophagy balance by regulating TOR activity in M. oryzae.
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Affiliation(s)
- Xue-Ming Zhu
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
| | - Lin Li
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
| | - Jian-Dong Bao
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
| | - Jiao-Yu Wang
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
| | - Shuang Liang
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
| | - Li-Li Zhao
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
| | - Chang-Li Huang
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
| | - Jiong-Yi Yan
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ying-Ying Cai
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xi-Yu Wu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Bo Dong
- Markey Cancer Center, University of Kentucky, College of Medicine, Lexington, KY, USA
| | - Xiao-Hong Liu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Daniel J. Klionsky
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Fu-Cheng Lin
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
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Montellà-Manuel S, Pujol-Carrion N, de la Torre-Ruiz MA. Aft1 Nuclear Localization and Transcriptional Response to Iron Starvation Rely upon TORC2/Ypk1 Signaling and Sphingolipid Biosynthesis. Int J Mol Sci 2023; 24. [PMID: 36768760 DOI: 10.3390/ijms24032438] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 01/20/2023] [Accepted: 01/24/2023] [Indexed: 01/28/2023] Open
Abstract
Iron scarcity provokes a cellular response consisting of the strong expression of high-affinity systems to optimize iron uptake and mobilization. Aft1 is a primary transcription factor involved in iron homeostasis and controls the expression of high-affinity iron uptake genes in Saccharomyces cerevisiae. Aft1 responds to iron deprivation by translocating from the cytoplasm to the nucleus. Here, we demonstrate that the AGC kinase Ypk1, as well as its upstream regulator TOR Complex 2 (TORC2), are required for proper Aft1 nuclear localization following iron deprivation. We exclude a role for TOR Complex 1 (TORC1) and its downstream effector Sch9, suggesting this response is specific for the TORC2 arm of the TOR pathway. Remarkably, we demonstrate that Aft1 nuclear localization and a robust transcriptional response to iron starvation also require biosynthesis of sphingolipids, including complex sphingolipids such as inositol phosphorylceramide (IPC) and upstream precursors, e.g., long-chain bases (LCBs) and ceramides. Furthermore, we observe the deficiency of Aft1 nuclear localization and impaired transcriptional response in the absence of iron when TORC2-Ypk1 is impaired is partially suppressed by exogenous addition of the LCB dihydrosphingosine (DHS). This latter result is consistent with prior studies linking sphingolipid biosynthesis to TORC2-Ypk1 signaling. Taken together, these results reveal a novel role for sphingolipids, controlled by TORC2-Ypk1, for proper localization and activity of Aft1 in response to iron scarcity.
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Nomura W, Ng SP, Takahara T, Maeda T, Kawada T, Goto T, Inoue Y. Roles of phosphatidylserine and phospholipase C in the activation of TOR complex 2 signaling in Saccharomyces cerevisiae. J Cell Sci 2022; 135:276172. [PMID: 35912799 DOI: 10.1242/jcs.259988] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 07/22/2022] [Indexed: 11/20/2022] Open
Abstract
The target of rapamycin (TOR) forms two distinct complexes, TORC1 and TORC2, to exert its functions essential for cellular growth and homeostasis. TORC1 signaling is regulated in response to nutrients such as amino acids and glucose; however, the mechanisms underlying the activation of TORC2 signaling are still poorly understood compared to TORC1 signaling. In the budding yeast Saccharomyces cerevisiae, TORC2 targets protein kinases Ypk1, Ypk2, and Pkc1 for phosphorylation. Plasma membrane stress is known to activate the TORC2-Ypk1/2 signaling. We have previously reported that methylglyoxal (MG), a metabolite derived from glycolysis, activates TORC2-Pkc1 signaling. In this study, we found that MG activates the TORC2-Ypk1/2 and TORC2-Pkc1 signaling, and that phosphatidylserine is involved in the activation of both signaling pathways. We also demonstrated that the Rho-family GTPase Cdc42 contributes to the plasma membrane stress-induced activation of TORC2-Ypk1/2 signaling. Furthermore, we revealed that phosphatidylinositol-specific phospholipase C, Plc1, contributes to the activation of both TORC2-Ypk1/2 and TORC2-Pkc1 signaling.
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Affiliation(s)
- Wataru Nomura
- Laboratory of Molecular Microbiology, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Su-Ping Ng
- Laboratory of Molecular Functions of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Terunao Takahara
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan
| | - Tatsuya Maeda
- Department of Biology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Teruo Kawada
- Laboratory of Molecular Functions of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Tsuyoshi Goto
- Laboratory of Molecular Functions of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Yoshiharu Inoue
- Laboratory of Molecular Microbiology, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
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Sakata KT, Hashii K, Yoshizawa K, Tahara YO, Yae K, Tsuda R, Tanaka N, Maeda T, Miyata M, Tabuchi M. Coordinated regulation of TORC2 signaling by MCC/eisosome-associated proteins, Pil1 and tetraspan membrane proteins during the stress response. Mol Microbiol 2022; 117:1227-1244. [PMID: 35383382 DOI: 10.1111/mmi.14903] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 11/28/2022]
Abstract
MCCs are linear invaginations of the yeast plasma membrane that form stable membrane microdomains. Although over 20 proteins are localized in the MCCs, it is not well understood how these proteins coordinately maintain normal MCC function. Pil1 is a core eisosome protein and is responsible for MCC-invaginated structures. In addition, six-tetraspan membrane proteins (6-Tsp) are localized in the MCCs and classified into two families, the Sur7 family and Nce102 family. To understand the coordinated function of these MCC proteins, single and multiple deletion mutants of Pil1 and 6-Tsp were generated and their MCC structure and growth under various stresses were investigated. Genetic interaction analysis revealed that the Sur7 family and Nce102 function in stress tolerance and normal eisosome assembly, respectively, by cooperating with Pil1. To further understand the role of MCCs/eisosomes in stress tolerance, we screened for suppressor mutants using the SDS-sensitive phenotype of pil1Δ 6-tspΔ cells. This revealed that SDS sensitivity is caused by hyperactivation of Tor kinase complex 2 (TORC2)-Ypk1 signaling. Interestingly, inhibition of sphingolipid metabolism, a well-known downstream pathway of TORC2-Ypk1 signaling, did not rescue the SDS-sensitivity of pil1Δ 6-tspΔ cells. These results suggest that Pil1 and 6-Tsp cooperatively regulate TORC2 signaling during the stress response.
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Affiliation(s)
- Ken-Taro Sakata
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa, Japan
| | - Keisuke Hashii
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa, Japan
| | - Koushiro Yoshizawa
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa, Japan
| | - Yuhei O Tahara
- Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan
| | - Kaori Yae
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa, Japan
| | - Ryohei Tsuda
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa, Japan
| | - Naotaka Tanaka
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa, Japan
| | - Tatsuya Maeda
- Department of Biology, Hamamatsu University School of Medicine, Handayama, Higashi-ku, Hamamatsu, Shizuoka, Japan
| | - Makoto Miyata
- Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan.,The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka, Japan
| | - Mitsuaki Tabuchi
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa, Japan
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Toyoda Y, Saitoh S. Fission Yeast TORC2 Signaling Pathway Ensures Cell Proliferation under Glucose-Limited, Nitrogen-Replete Conditions. Biomolecules 2021; 11:1465. [PMID: 34680098 DOI: 10.3390/biom11101465] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/29/2021] [Accepted: 10/02/2021] [Indexed: 12/25/2022] Open
Abstract
Target of rapamycin (TOR) kinases form two distinct complexes, TORC1 and TORC2, which are evolutionarily conserved among eukaryotes. These complexes control intracellular biochemical processes in response to changes in extracellular nutrient conditions. Previous studies using the fission yeast, Schizosaccharomyces pombe, showed that the TORC2 signaling pathway, which is essential for cell proliferation under glucose-limited conditions, ensures cell-surface localization of a high-affinity hexose transporter, Ght5, by downregulating its endocytosis. The TORC2 signaling pathway retains Ght5 on the cell surface, depending on the presence of nitrogen sources in medium. Ght5 is transported to vacuoles upon nitrogen starvation. In this review, we discuss the molecular mechanisms underlying this regulation to cope with nutritional stress, a response which may be conserved from yeasts to mammals.
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8
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Abstract
Almost three decades after its seminal discovery, our understanding of the remarkable TOR pathway continues to expand. As a TOR complex, TORC2 lies at the nexus of many signaling pathways and directs a diverse array of fundamental processes such as cell survival, proliferation, and metabolism by integrating environmental and intracellular cues. The dysregulation of TORC2 activity disrupts cellular homeostasis and leads to many pathophysiological conditions. With continued efforts at mapping the signaling landscape, the pace of discovery in TORC2 regulation has been accelerated in recent years. Consequently, emerging evidence has expanded the repertoire of upstream regulators and has revealed unexpected diversity in the modes of TORC2 regulation. Multiple environmental cues and plasma membrane proteins that fine-tune TORC2 activity are unfolding. Furthermore, TORC2 signaling is intricately intertwined with other major signaling pathways. Therefore, feedback and crosstalk regulation also extensively modulate TORC2. In this context, we provide a comprehensive overview of revolutionary concepts regarding emerging regulators of TORC2 and discuss evidence of feedback and crosstalk regulation that shed new light on TORC2 biology.
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Affiliation(s)
- Peng An
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Wenyi Xu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Junjie Luo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Yongting Luo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
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9
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Halova L, Cobley D, Franz-Wachtel M, Wang T, Morrison KR, Krug K, Nalpas N, Maček B, Hagan IM, Humphrey SJ, Petersen J. A TOR (target of rapamycin) and nutritional phosphoproteome of fission yeast reveals novel targets in networks conserved in humans. Open Biol 2021; 11:200405. [PMID: 33823663 PMCID: PMC8025308 DOI: 10.1098/rsob.200405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/05/2021] [Indexed: 12/21/2022] Open
Abstract
Fluctuations in TOR, AMPK and MAP-kinase signalling maintain cellular homeostasis and coordinate growth and division with environmental context. We have applied quantitative, SILAC mass spectrometry to map TOR and nutrient-controlled signalling in the fission yeast Schizosaccharomyces pombe. Phosphorylation levels at more than 1000 sites were altered following nitrogen stress or Torin1 inhibition of the TORC1 and TORC2 networks that comprise TOR signalling. One hundred and thirty of these sites were regulated by both perturbations, and the majority of these (119) new targets have not previously been linked to either nutritional or TOR control in either yeasts or humans. Elimination of AMPK inhibition of TORC1, by removal of AMPKα (ssp2::ura4+), identified phosphosites where nitrogen stress-induced changes were independent of TOR control. Using a yeast strain with an ATP analogue-sensitized Cdc2 kinase, we excluded sites that were changed as an indirect consequence of mitotic control modulation by nitrogen stress or TOR signalling. Nutritional control of gene expression was reflected in multiple targets in RNA metabolism, while significant modulation of actin cytoskeletal components points to adaptations in morphogenesis and cell integrity networks. Reduced phosphorylation of the MAPKK Byr1, at a site whose human equivalent controls docking between MEK and ERK, prevented sexual differentiation when resources were sparse but not eliminated.
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Affiliation(s)
- Lenka Halova
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
- Cancer Research UK Manchester Institute, Alderley Park, Macclesfield SK10 4TG, UK
| | - David Cobley
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Mirita Franz-Wachtel
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Tingting Wang
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia 5042, Australia
| | - Kaitlin R. Morrison
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia 5042, Australia
| | - Karsten Krug
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Nicolas Nalpas
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Boris Maček
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Iain M. Hagan
- Cancer Research UK Manchester Institute, Alderley Park, Macclesfield SK10 4TG, UK
| | - Sean J. Humphrey
- Charles Perkins Centre, School of Life and Environmental Sciences, The University of Sydney, Camperdown, New South Wales, Australia
| | - Janni Petersen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia 5042, Australia
- Nutrition and Metabolism, South Australia Health and Medical Research Institute, North Terrace, Adelaide, South Australia 5000, Australia
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Alao JP, Legon L, Rallis C. Crosstalk between the mTOR and DNA Damage Response Pathways in Fission Yeast. Cells 2021; 10:cells10020305. [PMID: 33540829 PMCID: PMC7913062 DOI: 10.3390/cells10020305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 12/14/2022] Open
Abstract
Cells have developed response systems to constantly monitor environmental changes and accordingly adjust growth, differentiation, and cellular stress programs. The evolutionarily conserved, nutrient-responsive, mechanistic target of rapamycin signaling (mTOR) pathway coordinates basic anabolic and catabolic cellular processes such as gene transcription, protein translation, autophagy, and metabolism, and is directly implicated in cellular and organismal aging as well as age-related diseases. mTOR mediates these processes in response to a broad range of inputs such as oxygen, amino acids, hormones, and energy levels, as well as stresses, including DNA damage. Here, we briefly summarize data relating to the interplays of the mTOR pathway with DNA damage response pathways in fission yeast, a favorite model in cell biology, and how these interactions shape cell decisions, growth, and cell-cycle progression. We, especially, comment on the roles of caffeine-mediated DNA-damage override. Understanding the biology of nutrient response, DNA damage and related pharmacological treatments can lead to the design of interventions towards improved cellular and organismal fitness, health, and survival.
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Affiliation(s)
- John-Patrick Alao
- ZEAB Therapeutic, University of East London, Stratford Campus, Water Lane, Stratford, London E15 4LZ, UK;
| | - Luc Legon
- School of Health, Sport and Bioscience, University of East London, Stratford Campus, Water Lane, Stratford, London E15 4LZ, UK;
| | - Charalampos Rallis
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
- Correspondence:
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Bjedov I, Rallis C. The Target of Rapamycin Signalling Pathway in Ageing and Lifespan Regulation. Genes (Basel) 2020; 11:E1043. [PMID: 32899412 PMCID: PMC7565554 DOI: 10.3390/genes11091043] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 08/28/2020] [Accepted: 08/30/2020] [Indexed: 12/11/2022] Open
Abstract
Ageing is a complex trait controlled by genes and the environment. The highly conserved mechanistic target of rapamycin signalling pathway (mTOR) is a major regulator of lifespan in all eukaryotes and is thought to be mediating some of the effects of dietary restriction. mTOR is a rheostat of energy sensing diverse inputs such as amino acids, oxygen, hormones, and stress and regulates lifespan by tuning cellular functions such as gene expression, ribosome biogenesis, proteostasis, and mitochondrial metabolism. Deregulation of the mTOR signalling pathway is implicated in multiple age-related diseases such as cancer, neurodegeneration, and auto-immunity. In this review, we briefly summarise some of the workings of mTOR in lifespan and ageing through the processes of transcription, translation, autophagy, and metabolism. A good understanding of the pathway's outputs and connectivity is paramount towards our ability for genetic and pharmacological interventions for healthy ageing and amelioration of age-related disease.
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Affiliation(s)
- Ivana Bjedov
- UCL Cancer Institute, Paul O’Gorman Building, 72 Huntley Street, London WC1E 6DD, UK
| | - Charalampos Rallis
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
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12
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Schmidt O, Weyer Y, Sprenger S, Widerin MA, Eising S, Baumann V, Angelova M, Loewith R, Stefan CJ, Hess MW, Fröhlich F, Teis D. TOR complex 2 ( TORC2) signaling and the ESCRT machinery cooperate in the protection of plasma membrane integrity in yeast. J Biol Chem 2020; 295:12028-12044. [PMID: 32611771 PMCID: PMC7443507 DOI: 10.1074/jbc.ra120.013222] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 06/24/2020] [Indexed: 12/26/2022] Open
Abstract
The endosomal sorting complexes required for transport (ESCRT) mediate evolutionarily conserved membrane remodeling processes. Here, we used budding yeast (Saccharomyces cerevisiae) to explore how the ESCRT machinery contributes to plasma membrane (PM) homeostasis. We found that in response to reduced membrane tension and inhibition of TOR complex 2 (TORC2), ESCRT-III/Vps4 assemblies form at the PM and help maintain membrane integrity. In turn, the growth of ESCRT mutants strongly depended on TORC2-mediated homeostatic regulation of sphingolipid (SL) metabolism. This was caused by calcineurin-dependent dephosphorylation of Orm2, a repressor of SL biosynthesis. Calcineurin activity impaired Orm2 export from the endoplasmic reticulum (ER) and thereby hampered its subsequent endosome and Golgi-associated degradation (EGAD). The ensuing accumulation of Orm2 at the ER in ESCRT mutants necessitated TORC2 signaling through its downstream kinase Ypk1, which repressed Orm2 and prevented a detrimental imbalance of SL metabolism. Our findings reveal compensatory cross-talk between the ESCRT machinery, calcineurin/TORC2 signaling, and the EGAD pathway important for the regulation of SL biosynthesis and the maintenance of PM homeostasis.
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Affiliation(s)
- Oliver Schmidt
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
| | - Yannick Weyer
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Simon Sprenger
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Michael A Widerin
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Sebastian Eising
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Verena Baumann
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Mihaela Angelova
- Cancer Evolution and Genome Instability Laboratory, Francis Crick Institute, London, United Kingdom
| | - Robbie Loewith
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Christopher J Stefan
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Michael W Hess
- Institute for Histology and Embryology, Medical University of Innsbruck, Innsbruck, Austria
| | - Florian Fröhlich
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - David Teis
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
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13
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Abstract
The target of rapamycin (TOR) protein kinase is at the core of growth factor- and nutrient-dependent signaling pathways that are well-known for their regulation of metabolism, growth, and proliferation. However, TOR is also involved in the regulation of gene expression, genomic and epigenomic stability. TOR affects nuclear functions indirectly through its activity in the cytoplasm, but also directly through active nuclear TOR pools. The mechanisms by which TOR regulates its nuclear functions are less well-understood compared with its cytoplasmic activities. TOR is an important pharmacological target for several diseases, including cancer, metabolic and neurological disorders. Thus, studies of the nuclear functions of TOR are important for our understanding of basic biological processes, as well as for clinical implications.
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Affiliation(s)
- R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and Center for Cancer Research, University of Tennessee Health Science Center, 19 South Manassas, Cancer Research Building Rm 318, Memphis, TN 38163, USA
| | - Ronit Weisman
- Department of Natural and Life Sciences, The Open University of Israel, University Road 1, Ra’anana 4353701, Israel
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14
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Abstract
Target of rapamycin (TOR) is a serine/threonine protein kinase conserved in most eukaryote organisms. TOR assembles into two multiprotein complexes (TORC1 and TORC2), which function as regulators of cellular growth and homeostasis by serving as direct transducers of extracellular biotic and abiotic signals, and, through their participation in intrinsic feedback loops, respectively. TORC1, the better-studied complex, is mainly involved in cell volume homeostasis through regulating accumulation of proteins and other macromolecules, while the functions of the lesser-studied TORC2 are only now starting to emerge. In this Cell Science at a Glance article and accompanying poster, we aim to highlight recent advances in our understanding of TORC2 signalling, particularly those derived from studies in yeast wherein TORC2 has emerged as a major regulator of cell surface homeostasis.
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Affiliation(s)
- Margot Riggi
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland.,Department of Biochemistry, University of Geneva, Geneva, Switzerland.,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Beata Kusmider
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland.,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Robbie Loewith
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland .,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
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15
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Abstract
The yeast plasma membrane is a selective barrier between an erratic environment and the cell's metabolism. Nutrient transporters are the gatekeepers that control the import of molecules feeding into the metabolic pathways. Nutrient import adjusts rapidly to changes in metabolism and the environment, which is accomplished by regulating the surface expression of transporters. Recent studies indicate that the lipid environment in which transporters function regulates ubiquitination efficiency and endocytosis of these proteins. Changes in the lipid environment are caused by lateral movements of the transporters between different membrane domains and by the influence of the extracellular environment on the fluidity of the plasma membrane.
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Affiliation(s)
- Markus Babst
- Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA.
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16
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Tarantelli C, Lupia A, Stathis A, Bertoni F. Is There a Role for Dual PI3K/mTOR Inhibitors for Patients Affected with Lymphoma? Int J Mol Sci 2020; 21:E1060. [PMID: 32033478 PMCID: PMC7037719 DOI: 10.3390/ijms21031060] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 01/31/2020] [Accepted: 02/03/2020] [Indexed: 12/12/2022] Open
Abstract
The activation of the PI3K/AKT/mTOR pathway is a main driver of cell growth, proliferation, survival, and chemoresistance of cancer cells, and, for this reason, represents an attractive target for developing targeted anti-cancer drugs. There are plenty of preclinical data sustaining the anti-tumor activity of dual PI3K/mTOR inhibitors as single agents and in combination in lymphomas. Clinical responses, including complete remissions (especially in follicular lymphoma patients), are also observed in the very few clinical studies performed in patients that are affected by relapsed/refractory lymphomas or chronic lymphocytic leukemia. In this review, we summarize the literature on dual PI3K/mTOR inhibitors focusing on the lymphoma setting, presenting both the three compounds still in clinical development and those with a clinical program stopped or put on hold.
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Affiliation(s)
- Chiara Tarantelli
- Institute of Oncology Research, Faculty of Biomedical Sciences, USI, 6500 Bellinzona, Switzerland;
| | - Antonio Lupia
- Department of Health Sciences, University “Magna Græcia” of Catanzaro, 88100 Catanzaro, Italy;
| | - Anastasios Stathis
- Oncology Institute of Southern Switzerland, 6500 Bellinzona, Switzerland;
- Faculty of Biomedical Sciences, USI, 6900 Lugano, Switzerland
| | - Francesco Bertoni
- Institute of Oncology Research, Faculty of Biomedical Sciences, USI, 6500 Bellinzona, Switzerland;
- Oncology Institute of Southern Switzerland, 6500 Bellinzona, Switzerland;
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17
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Khan R, Raza SHA, Junjvlieke Z, Wang H, Cheng G, Smith SB, Jiang Z, Li A, Zan L. RNA-seq reveal role of bovine TORC2 in the regulation of adipogenesis. Arch Biochem Biophys 2019; 680:108236. [PMID: 31893525 DOI: 10.1016/j.abb.2019.108236] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 12/05/2019] [Accepted: 12/20/2019] [Indexed: 12/18/2022]
Abstract
Low intramuscular adipose tissue (marbling) continues to be challenge for improving beef quality in Chinese cattle. Highly marbled meat is very desirable; hence, methods to increase IMF content have become a key aspect of improving meat quality. Therefore, research on the mechanism of adipogenesis provides invaluable information for the improvement of meat quality. This study investigated the effect of TORC2 and its underlying mechanism on lipid metabolism in bovine adipocytes. The TORC2 gene was downregulated in bovine adipocytes by siRNA, and RNA sequencing was performed. Downregulation of TORC2 negatively affected bovine adipocyte differentiation. In addition, a total of 577 DEGs were found, containing 146 up-regulated and 376 down-regulated genes. KEGG pathway analysis revealed that the DEGs were linked with neuroactive ligand-receptor interaction pathway, calcium signaling pathway, cAMP pathway, chemokine signaling pathway and Wnt signaling pathway. Gene Ontology (GO) term analysis of the DEGs showed that down-regulation of TORC2 gene significantly suppressed the genes regulating important GO terms of adipogenesis-related processes in bovine adipocytes, especially regulation of biological activity, regulation of primary metabolic process, regulation of multicellular organismal process, cell adhesion, lipid metabolic process, secretion, chemical homeostasis, regulation of transport, cell-cell signaling, cAMP metabolic process, cellular calcium ion homeostasis, fat cell differentiation, and cell maturation. In conclusion, our results suggest that TORC2 at least in part regulates lipid metabolism in bovine adipocytes. The results of this study provide a basis for studying the function and molecular mechanism of the TORC2 gene in regulating adipogenesis.
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Affiliation(s)
- Rajwali Khan
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China.
| | - Sayed Haidar Abbas Raza
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China.
| | - Zainaguli Junjvlieke
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Hongbao Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Gong Cheng
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Stephen B Smith
- Department of Animal Science, Texas A&M University, College Station, TX, 77843, USA
| | - Zhongliang Jiang
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Anning Li
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Linsen Zan
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China; National Beef Cattle Improvement Center, Northwest A&F University, Yangling, 712100, China.
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18
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Abstract
The Target of Rapamycin (TOR or mTOR) is a serine/threonine kinase that regulates growth, development, and behaviors by modulating protein synthesis, autophagy, and multiple other cellular processes in response to changes in nutrients and other cues. Over recent years, TOR has been studied intensively in mammalian cell culture and genetic systems because of its importance in growth, metabolism, cancer, and aging. Through its advantages for unbiased, and high-throughput, genetic and in vivo studies, Caenorhabditis elegans has made major contributions to our understanding of TOR biology. Genetic analyses in the worm have revealed unexpected aspects of TOR functions and regulation, and have the potential to further expand our understanding of how growth and metabolic regulation influence development. In the aging field, C. elegans has played a leading role in revealing the promise of TOR inhibition as a strategy for extending life span, and identifying mechanisms that function upstream and downstream of TOR to influence aging. Here, we review the state of the TOR field in C. elegans, and focus on what we have learned about its functions in development, metabolism, and aging. We discuss knowledge gaps, including the potential pitfalls in translating findings back and forth across organisms, but also describe how TOR is important for C. elegans biology, and how C. elegans work has developed paradigms of great importance for the broader TOR field.
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Affiliation(s)
- T Keith Blackwell
- Research Division, Joslin Diabetes Center, Department of Genetics, Harvard Medical School, Harvard Stem Cell Institute, Boston, Massachusetts
| | - Aileen K Sewell
- Department of MCDB, University of Colorado at Boulder, and
- Howard Hughes Medical Institute, Boulder, Colorado
| | - Ziyun Wu
- Research Division, Joslin Diabetes Center, Department of Genetics, Harvard Medical School, Harvard Stem Cell Institute, Boston, Massachusetts
| | - Min Han
- Department of MCDB, University of Colorado at Boulder, and
- Howard Hughes Medical Institute, Boulder, Colorado
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19
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Baker K, Gyamfi IA, Mashanov GI, Molloy JE, Geeves MA, Mulvihill DP. TORC2-Gad8-dependent myosin phosphorylation modulates regulation by calcium. eLife 2019; 8:e51150. [PMID: 31566560 PMCID: PMC6802964 DOI: 10.7554/elife.51150] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 09/26/2019] [Indexed: 01/22/2023] Open
Abstract
Cells respond to changes in their environment through signaling networks that modulate cytoskeleton and membrane organization to coordinate cell-cycle progression, polarized cell growth and multicellular development. Here, we define a novel regulatory mechanism by which the motor activity and function of the fission yeast type one myosin, Myo1, is modulated by TORC2-signalling-dependent phosphorylation. Phosphorylation of the conserved serine at position 742 (S742) within the neck region changes both the conformation of the neck region and the interactions between Myo1 and its associating calmodulin light chains. S742 phosphorylation thereby couples the calcium and TOR signaling networks that are involved in the modulation of myosin-1 dynamics to co-ordinate actin polymerization and membrane reorganization at sites of endocytosis and polarised cell growth in response to environmental and cell-cycle cues.
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Affiliation(s)
- Karen Baker
- School of BiosciencesUniversity of KentCanterburyUnited Kingdom
| | - Irene A Gyamfi
- School of BiosciencesUniversity of KentCanterburyUnited Kingdom
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20
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Khan R, Raza SHA, Junjvlieke Z, Xiaoyu W, Garcia M, Elnour IE, Hongbao W, Linsen Z. Function and Transcriptional Regulation of Bovine TORC2 Gene in Adipocytes: Roles of C/EBP, XBP1, INSM1 and ZNF263. Int J Mol Sci 2019; 20:E4338. [PMID: 31487963 DOI: 10.3390/ijms20184338] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 09/01/2019] [Accepted: 09/01/2019] [Indexed: 12/25/2022] Open
Abstract
The TORC2 gene is a member of the transducer of the regulated cyclic adenosine monophosphate (cAMP) response element binding protein gene family, which plays a key role in metabolism and adipogenesis. In the present study, we confirmed the role of TORC2 in bovine preadipocyte proliferation through cell cycle staining flow cytometry, cell counting assay, 5-ethynyl-2′-deoxyuridine staining (EdU), and mRNA and protein expression analysis of proliferation-related marker genes. In addition, Oil red O staining analysis, immunofluorescence of adiponectin, mRNA and protein level expression of lipid related marker genes confirmed the role of TORC2 in the regulation of bovine adipocyte differentiation. Furthermore, the transcription start site and sub-cellular localization of the TORC2 gene was identified in bovine adipocytes. To investigate the underlying regulatory mechanism of the bovine TORC2, we cloned a 1990 bp of the 5’ untranslated region (5′UTR) promoter region into a luciferase reporter vector and seven vector fragments were constructed through serial deletion of the 5′UTR flanking region. The core promoter region of the TORC2 gene was identified at location −314 to −69 bp upstream of the transcription start site. Based on the results of the transcriptional activities of the promoter vector fragments, luciferase activities of mutated fragments and siRNAs interference, four transcription factors (CCAAT/enhancer-binding protein C/BEPγ, X-box binding protein 1 XBP1, Insulinoma-associated 1 INSM1, and Zinc finger protein 263 ZNF263) were identified as the transcriptional regulators of TORC2 gene. These findings were further confirmed through Electrophoretic Mobility Shift Assay (EMSA) within nuclear extracts of bovine adipocytes. Furthermore, we also identified that C/EBPγ, XBP1, INSM1 and ZNF263 regulate TORC2 gene as activators in the promoter region. We can conclude that TORC2 gene is potentially a positive regulator of adipogenesis. These findings will not only provide an insight for the improvement of intramuscular fat in cattle, but will enhance our understanding regarding therapeutic intervention of metabolic syndrome and obesity in public health as well.
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21
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Ji X, Wang S, Tang H, Zhang Y, Zhou F, Zhang L, Zhu Q, Zhu K, Liu Q, Liu Y, Wang X, Zhou L. PPP1R3C mediates metformin-inhibited hepatic gluconeogenesis. Metabolism 2019; 98:62-75. [PMID: 31181215 DOI: 10.1016/j.metabol.2019.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/15/2019] [Accepted: 06/05/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Metformin has been widely used to alleviate hyperglycemia in patients with type 2 diabetes mainly via suppressing hepatic gluconeogenesis. However, the underlying mechanism remains incompletely clear. Here, we aimed to explore the role of PPP1R3C in metformin-mediated inhibition of hepatic gluconeogenesis. METHODS The differentially expressed genes in primary mouse hepatocytes incubated with 8-Br-cAMP and metformin were analyzed by microarrays. Hepatic glucose production and gluconeogenic gene expressions were detected after adenovirus-mediated overexpression or silence of PPP1R3C in vitro and in vivo. The phosphorylation level and location of transducer of regulated CREB activity 2 (TORC2) were determined by Western blot and immunofluorescence. RESULTS Metformin and adenovirus-mediated activation of AMPK suppressed 8-Br-cAMP-stimulated Ppp1r3c mRNA expression in primary mouse hepatocytes. Overexpression of PPP1R3C in primary mouse hepatocytes or the livers of wild-type mice promoted hepatic glucose production and gluconeogenic gene expressions. On the contrary, adenovirus-mediated knockdown of PPP1R3C in primary mouse hepatocytes decreased hepatic gluconeogenesis, with the suppression of cAMP-stimulated gluconeogenic gene expressions and TORC2 dephosphorylation. Notably, Ppp1r3c expression was increased in the liver of db/db mice. After PPP1R3C silence in the livers of wild-type and db/db mice, blood glucose levels and hepatic glucose production were markedly lowered, with decreased expressions of key gluconeogenic enzymes and transcript factors as well as liver glycogen content. CONCLUSION Metformin-activated AMPK decreases hepatic PPP1R3C expression, leading to the suppression of hepatic gluconeogenesis through blocking cAMP-stimulated TORC2 dephosphorylation. Hepatic specific silence of PPP1R3C provides a promising therapeutic strategy for type 2 diabetes.
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Affiliation(s)
- Xueying Ji
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China
| | - Shushu Wang
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China
| | - Hongju Tang
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China; The Department of Geriatrics, The People's of Wenshan Prefecture, Wenshan 663099, PR China
| | - Yuqing Zhang
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China
| | - Feiye Zhou
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China
| | - Linlin Zhang
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China
| | - Qin Zhu
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China
| | - Kecheng Zhu
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China
| | - Qianqian Liu
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China
| | - Yun Liu
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China
| | - Xiao Wang
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China.
| | - Libin Zhou
- Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, PR China.
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22
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Abstract
Eisosomes are furrows in the yeast plasma membrane that form a membrane domain with distinct lipid and protein composition. Recent studies highlighted the importance of this domain for the regulation of proton-nutrient symporters. The amino acids and other nutrients, which these transporters deliver to the cytoplasm not only feed into metabolic pathways but also activate the metabolic regulator TORC1. Eisosomes have also been shown to harbor the membrane stress sensors Slm1 and Slm2. Membrane tension caused by hypoosmotic shock results in the redistribution of Slm1/2 from eisosomes to TORC2 which in turn regulates lipid synthesis. Therefore, eisosomes function upstream of both TORC1 and TORC2 regulation.
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Affiliation(s)
- Markus Babst
- Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah
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23
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Lie S, Banks P, Lawless C, Lydall D, Petersen J. The contribution of non-essential Schizosaccharomyces pombe genes to fitness in response to altered nutrient supply and target of rapamycin activity. Open Biol 2019; 8:rsob.180015. [PMID: 29720420 PMCID: PMC5990653 DOI: 10.1098/rsob.180015] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 04/06/2018] [Indexed: 12/12/2022] Open
Abstract
Nutrient fluctuations in the cellular environment promote changes in cell metabolism and growth to adapt cell proliferation accordingly. The target of rapamycin (TOR) signalling network plays a key role in the coordination of growth and cell proliferation with the nutrient environment and, importantly, nutrient limitation reduces TOR complex 1 (TORC1) signalling. We have performed global quantitative fitness profiling of the collection of Schizosaccharomyces pombe strains from which non-essential genes have been deleted. We identified genes that regulate fitness when cells are grown in a nutrient-rich environment compared with minimal environments, with varying nitrogen sources including ammonium, glutamate and proline. In addition, we have performed the first global screen for genes that regulate fitness when both TORC1 and TORC2 signalling is reduced by Torin1. Analysis of genes whose deletions altered fitness when nutrients were limited, or when TOR signalling was compromised, identified a large number of genes that regulate transmembrane transport, transcription and chromatin organization/regulation and vesicle-mediated transport. The ability to tolerate reduced TOR signalling placed demands upon a large number of biological processes including autophagy, mRNA metabolic processing and nucleocytoplasmic transport. Importantly, novel biological processes and all processes known to be regulated by TOR were identified in our screens. In addition, deletion of 62 genes conserved in humans gave rise to strong sensitivity or resistance to Torin1, and 29 of these 62 genes have novel links to TOR signalling. The identification of chromatin and transcriptional regulation, nutritional uptake and transport pathways in this powerful genetic model now paves the way for a molecular understanding of how cells adapt to the chronic and acute fluctuations in nutrient supply that all eukaryotes experience at some stage, and which is a key feature of cancer cells within solid tumours.
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Affiliation(s)
- Shervi Lie
- Flinders Centre for Innovation in Cancer, College of Medicine & Public Health, Flinders University, Bedford Park, Adelaide, South Australia 5042, Australia
| | - Peter Banks
- High Throughput Screening Facility, Newcastle Biomedicine, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Conor Lawless
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - David Lydall
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - Janni Petersen
- Flinders Centre for Innovation in Cancer, College of Medicine & Public Health, Flinders University, Bedford Park, Adelaide, South Australia 5042, Australia .,South Australia Health and Medical Research Institute, North Terrace, PO Box 11060, Adelaide, South Australia 5000, Australia
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24
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Alcaide-Gavilán M, Lucena R, Schubert KA, Artiles KL, Zapata J, Kellogg DR. Modulation of TORC2 Signaling by a Conserved Lkb1 Signaling Axis in Budding Yeast. Genetics 2018; 210:155-70. [PMID: 29986907 DOI: 10.1534/genetics.118.301296] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 06/29/2018] [Indexed: 01/03/2023] Open
Abstract
Nutrient availability, growth rate, and cell size are closely linked. For example, in budding yeast, the rate of cell growth is proportional to nutrient availability, cell size is proportional to growth rate, and growth rate is proportional to cell size. Thus, cells grow slowly in poor nutrients and are nearly half the size of cells growing in rich nutrients. Moreover, large cells grow faster than small cells. A signaling network that surrounds TOR kinase complex 2 (TORC2) plays an important role in enforcing these proportional relationships. Cells that lack components of the TORC2 network fail to modulate their growth rate or size in response to changes in nutrient availability. Here, we show that budding yeast homologs of the Lkb1 tumor suppressor kinase are required for normal modulation of TORC2 signaling in response to changes in carbon source. Lkb1 kinases activate Snf1/AMPK to initiate transcription of genes required for utilization of poor carbon sources. However, Lkb1 influences TORC2 signaling via a novel pathway that is independent of Snf1/AMPK. Of the three Lkb1 homologs in budding yeast, Elm1 plays the most important role in modulating TORC2. Elm1 activates a pair of related kinases called Gin4 and Hsl1. Previous work found that loss of Gin4 and Hsl1 causes cells to undergo unrestrained growth during a prolonged mitotic arrest, which suggests that they play a role in linking cell cycle progression to cell growth. We found that Gin4 and Hsl1 also control the TORC2 network. In addition, Gin4 and Hsl1 are themselves influenced by signals from the TORC2 network, consistent with previous work showing that the TORC2 network constitutes a feedback loop. Together, the data suggest a model in which the TORC2 network sets growth rate in response to carbon source, while also relaying signals via Gin4 and Hsl1 that set the critical amount of growth required for cell cycle progression. This kind of close linkage between control of cell growth and size would suggest a simple mechanistic explanation for the proportional relationship between cell size and growth rate.
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Cohen A, Habib A, Laor D, Yadav S, Kupiec M, Weisman R. TOR complex 2 in fission yeast is required for chromatin-mediated gene silencing and assembly of heterochromatic domains at subtelomeres. J Biol Chem 2018; 293:8138-8150. [PMID: 29632066 DOI: 10.1074/jbc.ra118.002270] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/14/2018] [Indexed: 12/21/2022] Open
Abstract
The conserved serine/threonine protein kinase target of rapamycin (TOR) is a major regulator of eukaryotic cellular and organismal growth and a valuable target for drug therapy. TOR forms the core of two evolutionary conserved complexes, TOR complex 1 (TORC1) and TORC2. In the fission yeast Schizosaccharomyces pombe, TORC2 responds to glucose levels and, by activating the protein kinase Gad8 (an orthologue of human AKT), is required for well-regulated cell cycle progression, starvation responses, and cell survival. Here, we report that TORC2-Gad8 is also required for gene silencing and the formation of heterochromatin at the S. pombe mating-type locus and at subtelomeric regions. Deletion of TORC2-Gad8 resulted in loss of the heterochromatic modification of histone 3 lysine 9 dimethylation (H3K9me2) and an increase in euchromatic modifications, including histone 3 lysine 4 trimethylation (H3K4me3) and histone 4 lysine 16 acetylation (H4K16Ac). Accumulation of RNA polymerase II (Pol II) at subtelomeric genes in TORC2-Gad8 mutant cells indicated a defect in silencing at the transcriptional level. Moreover, a concurrent decrease in histone 4 lysine 20 dimethylation (H4K20me2) suggested elevated histone turnover. Loss of gene silencing in cells lacking TORC2-Gad8 is partially suppressed by loss of the anti-silencer Epe1 and fully suppressed by loss of the Pol II-associated Paf1 complex, two chromatin regulators that have been implicated in heterochromatin stability and spreading. Taken together, our findings suggest that TORC2-Gad8 signaling contributes to epigenetic stability at subtelomeric regions and the mating-type locus in S. pombe.
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Affiliation(s)
- Adiel Cohen
- Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana, Israel
| | - Aline Habib
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Dana Laor
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Sudhanshu Yadav
- Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana, Israel
| | - Martin Kupiec
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Ronit Weisman
- Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana, Israel.
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Lucena R, Alcaide-Gavilán M, Schubert K, He M, Domnauer MG, Marquer C, Klose C, Surma MA, Kellogg DR. Cell Size and Growth Rate Are Modulated by TORC2-Dependent Signals. Curr Biol 2017; 28:196-210.e4. [PMID: 29290562 DOI: 10.1016/j.cub.2017.11.069] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 10/19/2017] [Accepted: 11/30/2017] [Indexed: 02/05/2023]
Abstract
The size of all cells, from bacteria to vertebrates, is proportional to the growth rate set by nutrient availability, but the underlying mechanisms are unknown. Here, we show that nutrients modulate cell size and growth rate via the TORC2 signaling network in budding yeast. An important function of the TORC2 network is to modulate synthesis of ceramide lipids, which play roles in signaling. TORC2-dependent control of ceramide signaling strongly influences both cell size and growth rate. Thus, cells that cannot make ceramides fail to modulate their growth rate or size in response to changes in nutrients. PP2A associated with the Rts1 regulatory subunit (PP2ARts1) is embedded in a feedback loop that controls TORC2 signaling and helps set the level of TORC2 signaling to match nutrient availability. Together, the data suggest a model in which growth rate and cell size are mechanistically linked by ceramide-dependent signals arising from the TORC2 network.
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Affiliation(s)
- Rafael Lucena
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Maria Alcaide-Gavilán
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Katherine Schubert
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Maybo He
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Matthew G Domnauer
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Catherine Marquer
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
| | | | | | - Douglas R Kellogg
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
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Tatebe H, Shiozaki K. Evolutionary Conservation of the Components in the TOR Signaling Pathways. Biomolecules 2017; 7:E77. [PMID: 29104218 DOI: 10.3390/biom7040077] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/26/2017] [Accepted: 10/27/2017] [Indexed: 01/08/2023] Open
Abstract
Target of rapamycin (TOR) is an evolutionarily conserved protein kinase that controls multiple cellular processes upon various intracellular and extracellular stimuli. Since its first discovery, extensive studies have been conducted both in yeast and animal species including humans. Those studies have revealed that TOR forms two structurally and physiologically distinct protein complexes; TOR complex 1 (TORC1) is ubiquitous among eukaryotes including animals, yeast, protozoa, and plants, while TOR complex 2 (TORC2) is conserved in diverse eukaryotic species other than plants. The studies have also identified two crucial regulators of mammalian TORC1 (mTORC1), Ras homolog enriched in brain (RHEB) and RAG GTPases. Of these, RAG regulates TORC1 in yeast as well and is conserved among eukaryotes with the green algae and land plants as apparent exceptions. RHEB is present in various eukaryotes but sporadically missing in multiple taxa. RHEB, in the budding yeast Saccharomyces cerevisiae, appears to be extremely divergent with concomitant loss of its function as a TORC1 regulator. In this review, we summarize the evolutionarily conserved functions of the key regulatory subunits of TORC1 and TORC2, namely RAPTOR, RICTOR, and SIN1. We also delve into the evolutionary conservation of RHEB and RAG and discuss the conserved roles of these GTPases in regulating TORC1.
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28
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Pergolizzi B, Bozzaro S, Bracco E. G-Protein Dependent Signal Transduction and Ubiquitination in Dictyostelium. Int J Mol Sci 2017; 18:ijms18102180. [PMID: 29048338 PMCID: PMC5666861 DOI: 10.3390/ijms18102180] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/12/2017] [Accepted: 10/16/2017] [Indexed: 12/20/2022] Open
Abstract
Signal transduction through G-protein-coupled receptors (GPCRs) is central for the regulation of virtually all cellular functions, and it has been widely implicated in human diseases. These receptors activate a common molecular switch that is represented by the heterotrimeric G-protein generating a number of second messengers (cAMP, cGMP, DAG, IP3, Ca2+ etc.), leading to a plethora of diverse cellular responses. Spatiotemporal regulation of signals generated by a given GPCR is crucial for proper signalling and is accomplished by a series of biochemical modifications. Over the past few years, it has become evident that many signalling proteins also undergo ubiquitination, a posttranslational modification that typically leads to protein degradation, but also mediates processes such as protein-protein interaction and protein subcellular localization. The social amoeba Dictyostelium discoideum has proven to be an excellent model to investigate signal transduction triggered by GPCR activation, as cAMP signalling via GPCR is a major regulator of chemotaxis, cell differentiation, and multicellular morphogenesis. Ubiquitin ligases have been recently involved in these processes. In the present review, we will summarize the most significant pathways activated upon GPCRs stimulation and discuss the role played by ubiquitination in Dictyostelium cells.
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Affiliation(s)
- Barbara Pergolizzi
- Department of Clinical and Biological Sciences, University of Turin, AOUS. Luigi, 10043 Orbassano TO, Italy.
| | - Salvatore Bozzaro
- Department of Clinical and Biological Sciences, University of Turin, AOUS. Luigi, 10043 Orbassano TO, Italy.
| | - Enrico Bracco
- Department of Oncology, University of Turin, AOU S. Luigi, 10043 Orbassano TO, Italy.
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Leskoske KL, Roelants FM, Martinez Marshall MN, Hill JM, Thorner J. The Stress-Sensing TORC2 Complex Activates Yeast AGC-Family Protein Kinase Ypk1 at Multiple Novel Sites. Genetics 2017; 207:179-95. [PMID: 28739659 DOI: 10.1534/genetics.117.1124] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 07/16/2017] [Indexed: 01/18/2023] Open
Abstract
Yeast (Saccharomyces cerevisiae) target of rapamycin (TOR) complex 2 (TORC2) is a multi-subunit plasma membrane-associated protein kinase and vital growth regulator. Its essential functions are exerted via phosphorylation and stimulation of downstream protein kinase Ypk1 (and its paralog Ypk2). Ypk1 phosphorylates multiple substrates to regulate plasma membrane lipid and protein composition. Ypk1 function requires phosphorylation of Thr504 in its activation loop by eisosome-associated Pkh1 (and its paralog Pkh2). For cell survival under certain stresses, however, Ypk1 activity requires further stimulation by TORC2-mediated phosphorylation at C-terminal sites, dubbed the “turn” (Ser644) and “hydrophobic” (Thr662) motifs. Here we show that four additional C-terminal sites are phosphorylated in a TORC2-dependent manner, collectively defining a minimal consensus. We found that the newly identified sites are as important for Ypk1 activity, stability, and biological function as Ser644 and Thr662. Ala substitutions at the four new sites abrogated the ability of Ypk1 to rescue the phenotypes of Ypk1 deficiency, whereas Glu substitutions had no ill effect. Combining the Ala substitutions with an N-terminal mutation (D242A), which has been demonstrated to bypass the need for TORC2-mediated phosphorylation, restored the ability to complement a Ypk1-deficient cell. These findings provide new insights about the molecular basis for TORC2-dependent activation of Ypk1.
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Abstract
The control of cell fate, growth and proliferation in response to nitrogen availability is a tightly controlled process, with the two TOR complexes (TORC1 and TORC2) and their effectors playing a central role. PP2A-B55Pab1 has recently been shown to be a key element in this response in fission yeast, where it regulates cell cycle progression and sexual differentiation. Importantly, a recent study from our group has shown that PP2A-B55Pab1 acts as a mediator between the activities of the two TOR signaling modules, enabling a crosstalk that is required to engage in the differentiation program. In this review, we recapitulate the studies that have led to our current understanding of the interplay between TOR complexes. Moreover, we discuss several aspects of the response to nitrogen availability that still require further attention, and which will be important in the future to fully realize the implications of phosphatase activity in the context of TOR signaling.
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Affiliation(s)
- Ruth Martín
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, Gaustadalleen 21, 0349, Oslo, Norway
| | - Sandra Lopez-Aviles
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, Gaustadalleen 21, 0349, Oslo, Norway.
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31
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Abstract
Cell size is amenable by genetic and environmental factors. The highly conserved nutrient-responsive Target of Rapamycin (TOR) signaling pathway regulates cellular metabolic status and growth in response to numerous inputs. Timing and duration of TOR pathway activity is pivotal for both cell mass built up as well as cell cycle progression and is controlled and fine-tuned by the abundance and quality of nutrients, hormonal signals, growth factors, stress, and oxygen. TOR kinases function within two functionally and structurally discrete multiprotein complexes, TORC1 and TORC2, that are implicated in temporal and spatial control of cell size and growth respectively; however, recent data indicate that such functional distinctions are much more complex. Here, we briefly review roles of the two complexes in cellular growth and cytoarchitecture in various experimental model systems.
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Affiliation(s)
- Suam Gonzalez
- School of Health, Sport and Bioscience, University of East LondonLondon, United Kingdom
| | - Charalampos Rallis
- School of Health, Sport and Bioscience, University of East LondonLondon, United Kingdom
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32
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Abstract
The target of rapamycin (TOR) kinase is a conserved regulator of cell growth and functions within 2 different protein complexes, TORC1 and TORC2, where TORC2 positively controls macroautophagy/autophagy during amino acid starvation. Under these conditions, TORC2 signaling inhibits the activity of the calcium-regulated phosphatase calcineurin and promotes the general amino acid control (GAAC) response and autophagy. Here we demonstrate that TORC2 regulates calcineurin by controlling the respiratory activity of mitochondria. In particular, we find that mitochondrial oxidative stress affects the calcium channel regulatory protein Mid1, which we show is an essential upstream activator of calcineurin. Thus, these findings describe a novel regulation for autophagy that involves TORC2 signaling, mitochondrial respiration, and calcium homeostasis.
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Affiliation(s)
- Ariadne Vlahakis
- a Department of Molecular and Cellular Biology , College of Biological Sciences, University of California , Davis , CA , USA
| | - Nerea Lopez Muniozguren
- a Department of Molecular and Cellular Biology , College of Biological Sciences, University of California , Davis , CA , USA
| | - Ted Powers
- a Department of Molecular and Cellular Biology , College of Biological Sciences, University of California , Davis , CA , USA
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33
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Pergolizzi B, Bracco E, Bozzaro S. A new HECT ubiquitin ligase regulating chemotaxis and development in Dictyostelium discoideum. J Cell Sci 2017; 130:551-562. [PMID: 28049717 DOI: 10.1242/jcs.194225] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 12/04/2016] [Indexed: 01/10/2023] Open
Abstract
Cyclic AMP (cAMP) binding to G-protein-coupled receptors (GPCRs) orchestrates chemotaxis and development in Dictyostelium. By activating the RasC-TORC2-PKB (PKB is also known as AKT in mammals) module, cAMP regulates cell polarization during chemotaxis. TORC2 also mediates GPCR-dependent stimulation of adenylyl cyclase A (ACA), enhancing cAMP relay and developmental gene expression. Thus, mutants defective in the TORC2 Pia subunit (also known as Rictor in mammals) are impaired in chemotaxis and development. Near-saturation mutagenesis of a Pia mutant by random gene disruption led to selection of two suppressor mutants in which spontaneous chemotaxis and development were restored. PKB phosphorylation and chemotactic cell polarization were rescued, whereas Pia-dependent ACA stimulation was not restored but bypassed, leading to cAMP-dependent developmental gene expression. Knocking out the gene encoding the adenylylcyclase B (ACB) in the parental strain showed ACB to be essential for this process. The gene tagged in the suppressor mutants encodes a newly unidentified HECT ubiquitin ligase that is homologous to mammalian HERC1, but harbours a pleckstrin homology domain. Expression of the isolated wild-type HECT domain, but not a mutant HECT C5185S form, from this protein was sufficient to reconstitute the parental phenotype. The new ubiquitin ligase appears to regulate cell sensitivity to cAMP signalling and TORC2-dependent PKB phosphorylation.
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Affiliation(s)
- Barbara Pergolizzi
- Department of Clinical and Biological Sciences, University of Torino, AOU S. Luigi, Orbassano (TO) 10043, Italy
| | - Enrico Bracco
- Department of Oncology, University of Torino, AOU S. Luigi, Orbassano (TO) 10043, Italy
| | - Salvatore Bozzaro
- Department of Clinical and Biological Sciences, University of Torino, AOU S. Luigi, Orbassano (TO) 10043, Italy
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Martín R, Portantier M, Chica N, Nyquist-Andersen M, Mata J, Lopez-Aviles S. A PP2A-B55-Mediated Crosstalk between TORC1 and TORC2 Regulates the Differentiation Response in Fission Yeast. Curr Biol 2016; 27:175-188. [PMID: 28041796 PMCID: PMC5266790 DOI: 10.1016/j.cub.2016.11.037] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 09/20/2016] [Accepted: 11/14/2016] [Indexed: 12/20/2022]
Abstract
Extracellular cues regulate cell fate, and this is mainly achieved through the engagement of specific transcriptional programs. The TORC1 and TORC2 complexes mediate the integration of nutritional cues to cellular behavior, but their interplay is poorly understood. Here, we use fission yeast to investigate how phosphatase activity participates in this interplay during the switch from proliferation to sexual differentiation. We find that loss of PP2A-B55Pab1 enhances the expression of differentiation-specific genes and leads to premature conjugation. pab1 deletion brings about a transcriptional profile similar to TORC1 inactivation, and deletion of pab1 overcomes the repression of differentiation genes in cells overexpressing TORC1. Importantly, we show that this effect is mediated by an increased TORC2-AKT (Gad8) signaling. Under nutrient-rich conditions, PP2A-B55Pab1 dephosphorylates Gad8 Ser546, repressing its activity. Conversely, TORC1 inactivation upon starvation leads to the inactivation of PP2A-B55Pab1 through the Greatwall-Endosulfin pathway. This results in the activation of Gad8 and the commitment to differentiation. Thus, PP2A-B55Pab1 enables a crosstalk between the two TOR complexes that controls cell-fate decisions in response to nutrient availability. PP2A-B55Pab1 regulates the differentiation response of fission yeast cells PP2A-B55Pab1 enables a crosstalk between TORC1 and TORC2 TORC1 favors PP2A-B55Pab1 activity to prevent the hyperphosphorylation of Gad8 TORC1 inactivation leads to PP2A-B55Pab1 inhibition, activation of Gad8, and differentiation
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Affiliation(s)
- Ruth Martín
- The Biotechnology Centre of Oslo, University of Oslo, Gaustadalléen 21, Oslo 0349, Norway
| | - Marina Portantier
- The Biotechnology Centre of Oslo, University of Oslo, Gaustadalléen 21, Oslo 0349, Norway
| | - Nathalia Chica
- The Biotechnology Centre of Oslo, University of Oslo, Gaustadalléen 21, Oslo 0349, Norway
| | - Mari Nyquist-Andersen
- The Biotechnology Centre of Oslo, University of Oslo, Gaustadalléen 21, Oslo 0349, Norway
| | - Juan Mata
- Department of Biochemistry, University of Cambridge, Building O, Downing Site, Cambridge CB2 1QW, UK
| | - Sandra Lopez-Aviles
- The Biotechnology Centre of Oslo, University of Oslo, Gaustadalléen 21, Oslo 0349, Norway.
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Abstract
Cell proliferation, metabolism, migration and survival are coordinated through the tight control of two target of rapamycin (TOR) kinase complexes: TORC1 and TORC2. Here, we show that a novel phosphorylation of fission yeast Gad8 (AGC kinase) on the evolutionarily conserved threonine 6 (Thr6) prevents the physical association between Gad8 and TORC2. Accordingly, this block to protein interactions by Gad8 Thr6 phosphorylation decreases TORC2-controlled activation of Gad8. Likewise, phosphorylation of Gad8 Thr6, possibly by PKC, prevents the association of Gad8 with TORC2 thereby increasing TORC2 activity, because it reduces Gad8-mediated feedback inhibition of TORC2. Consistently, the introduction of a Gad8 T6D mutant, that mimics phosphorylation, increased TORC2 activity. Increased PKCPck2 expression prevented Gad8–TORC2 binding and so reduced the TORC2-mediated phosphorylation of Gad8 serine 546 that activates Gad8. Interestingly, independent of the Ser546 phosphorylation status, Gad8 Thr6 phosphorylation is important for remodelling the actin cytoskeleton and survival upon potassium ion and heat stresses. In contrast, Ser546 phosphorylation is required for the control of G1 arrest, mating, cell length at division and vascular size. Finally, these findings reveal a novel mode of TORC2 activation that is essential for cell survival following stress.
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Affiliation(s)
- Wei Du
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Gabriella M Forte
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Duncan Smith
- Biological Mass Spectrometry, Cancer Research UK Manchester Institute, The Paterson Building, Wilmslow Road, Manchester M20 4BX, UK
| | - Janni Petersen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK Flinders Centre for Innovation in Cancer, School of Medicine, Flinders University, Adelaide, South Australia 5001, Australia South Australia Health and Medical Research Institute, North Terrace, PO Box 11060, Adelaide, South Australia 5000, Australia
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Abstract
The directional movement toward extracellular chemical gradients, a process called chemotaxis, is an important property of cells. Central to eukaryotic chemotaxis is the molecular mechanism by which chemoattractant-mediated activation of G-protein coupled receptors (GPCRs) induces symmetry breaking in the activated downstream signaling pathways. Studies with mainly Dictyostelium and mammalian neutrophils as experimental systems have shown that chemotaxis is mediated by a complex network of signaling pathways. Recently, several labs have used extensive and efficient proteomic approaches to further unravel this dynamic signaling network. Together these studies showed the critical role of the interplay between heterotrimeric G-protein subunits and monomeric G proteins in regulating cytoskeletal rearrangements during chemotaxis. Here we highlight how these proteomic studies have provided greater insight into the mechanisms by which the heterotrimeric G protein cycle is regulated, how heterotrimeric G proteins-induced symmetry breaking is mediated through small G protein signaling, and how symmetry breaking in G protein signaling subsequently induces cytoskeleton rearrangements and cell migration.
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Affiliation(s)
- Youtao Liu
- a Department of Cell Biochemistry , University of Groningen , Groningen , The Netherlands
| | - Jesus Lacal
- b Section of Cell and Developmental Biology, Division of Biological Sciences, University of California , San Diego, La Jolla , CA , USA
| | - Richard A Firtel
- b Section of Cell and Developmental Biology, Division of Biological Sciences, University of California , San Diego, La Jolla , CA , USA
| | - Arjan Kortholt
- a Department of Cell Biochemistry , University of Groningen , Groningen , The Netherlands
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37
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Amin DN, Ruiz-Saenz A, Gulizia N, Moasser MM. Chemical probing of HER2-amplified cancer cells identifies TORC2 as a particularly effective secondary target for combination with lapatinib. Oncotarget 2016; 6:41123-33. [PMID: 26516700 PMCID: PMC4747394 DOI: 10.18632/oncotarget.5660] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 09/12/2015] [Indexed: 01/01/2023] Open
Abstract
The clinical impact of HER2 inhibitors in the treatment of HER2-amplified breast cancers has been largely confined to chemotherapy combination regimens, since HER2 inhibitors appear to have very modest efficacies by themselves. This is due to the resilient nature of the functionally relevant HER2-HER3 tumor driver, bidirectionally linked with downstream PI3K/Akt pathway signaling, which can break through the inhibitory effects of most current HER2 or HER3 targeting therapies. A vertical combination approach targeting HER2 and a downstream pathway is a highly rational strategy for much more effective targeted therapy of this disease. However the importance of these downstream pathways in many human tissues and cells significant limits their usefulness as secondary targets by narrowing the therapeutic index of such combination therapies. The secondary target that can afford the highest potential for clinical translation is the one with the highest synergy against tumor cells in combination with HER2-inhibition, allowing the widest therapeutic index for clinical translation. We conducted a comparative analysis of such secondary targets in combination with the HER2 inhibitor lapatinib and find that the inhibition of mTor affords the highest degree of synergy. In further dissecting the individual roles of TORC1 and TORC2 complexes using pharmacologic and genetic tools, we find that it is specifically the inactivation of TORC2 that most synergistically enhances the efficacy of lapatinib. Although inhibitors that selectively target TORC2 are not currently available, these data make a compelling case for their development.
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Affiliation(s)
- Dhara N Amin
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94143, USA
| | - Ana Ruiz-Saenz
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94143, USA
| | - Nathaniel Gulizia
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94143, USA
| | - Mark M Moasser
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94143, USA
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Baker K, Kirkham S, Halova L, Atkin J, Franz-Wachtel M, Cobley D, Krug K, Maček B, Mulvihill DP, Petersen J. TOR complex 2 localises to the cytokinetic actomyosin ring and controls the fidelity of cytokinesis. J Cell Sci 2016; 129:2613-24. [PMID: 27206859 PMCID: PMC4958305 DOI: 10.1242/jcs.190124] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 05/06/2016] [Indexed: 01/30/2023] Open
Abstract
The timing of cell division is controlled by the coupled regulation of growth and division. The target of rapamycin (TOR) signalling network synchronises these processes with the environmental setting. Here, we describe a novel interaction of the fission yeast TOR complex 2 (TORC2) with the cytokinetic actomyosin ring (CAR), and a novel role for TORC2 in regulating the timing and fidelity of cytokinesis. Disruption of TORC2 or its localisation results in defects in CAR morphology and constriction. We provide evidence that the myosin II protein Myp2 and the myosin V protein Myo51 play roles in recruiting TORC2 to the CAR. We show that Myp2 and TORC2 are co-dependent upon each other for their normal localisation to the cytokinetic machinery. We go on to show that TORC2-dependent phosphorylation of actin-capping protein 1 (Acp1, a known regulator of cytokinesis) controls CAR stability, modulates Acp1-Acp2 (the equivalent of the mammalian CAPZA-CAPZB) heterodimer formation and is essential for survival upon stress. Thus, TORC2 localisation to the CAR, and TORC2-dependent Acp1 phosphorylation contributes to timely control and the fidelity of cytokinesis and cell division.
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Affiliation(s)
- Karen Baker
- School of Biosciences, University of Kent, Giles Lane, Canterbury, Kent CT2 7NJ, UK
| | - Sara Kirkham
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Lenka Halova
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Jane Atkin
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | | | - David Cobley
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Karsten Krug
- Proteome Center Tübingen, Auf der Morgenstelle 15, Tübingen 72076, Germany
| | - Boris Maček
- Proteome Center Tübingen, Auf der Morgenstelle 15, Tübingen 72076, Germany
| | - Daniel P Mulvihill
- School of Biosciences, University of Kent, Giles Lane, Canterbury, Kent CT2 7NJ, UK
| | - Janni Petersen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK Flinders Centre for Innovation in Cancer, School of Medicine, Flinders University, Adelaide, SA 5001, Australia South Australia Health and Medical Research Institute, North Terrace, PO Box 11060, Adelaide, SA 5000, Australia
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Allen VW, O'Connor RM, Ulgherait M, Zhou CG, Stone EF, Hill VM, Murphy KR, Canman JC, Ja WW, Shirasu-Hiza MM. period-Regulated Feeding Behavior and TOR Signaling Modulate Survival of Infection. Curr Biol 2015; 26:184-194. [PMID: 26748856 DOI: 10.1016/j.cub.2015.11.051] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 10/16/2015] [Accepted: 11/23/2015] [Indexed: 12/23/2022]
Abstract
Most metazoans undergo dynamic, circadian-regulated changes in behavior and physiology. Currently, it is unknown how circadian-regulated behavior impacts immunity against infection. Two broad categories of defense against bacterial infection are resistance, control of microbial growth, and tolerance, control of the pathogenic effects of infection. Our study of behaviorally arrhythmic Drosophila circadian period mutants identified a novel link between nutrient intake and tolerance of infection with B. cepacia, a bacterial pathogen of rising importance in hospital-acquired infections. We found that infection tolerance in wild-type animals is stimulated by acute exposure to dietary glucose and amino acids. Glucose-stimulated tolerance was induced by feeding or direct injection; injections revealed a narrow window for glucose-stimulated tolerance. In contrast, amino acids stimulated tolerance only when ingested. We investigated the role of a known amino-acid-sensing pathway, the TOR (Target of Rapamycin) pathway, in immunity. TORC1 is circadian regulated and inhibition of TORC1 decreased resistance, as in vertebrates. Surprisingly, inhibition of the less well-characterized TOR complex 2 (TORC2) dramatically increased survival, through both resistance and tolerance mechanisms. This work suggests that dietary intake on the day of infection by B. cepacia can make a significant difference in long-term survival. We further demonstrate that TOR signaling mediates both resistance and tolerance of infection and identify TORC2 as a novel potential therapeutic target for increasing survival of infection.
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Affiliation(s)
- Victoria W Allen
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA
| | - Reed M O'Connor
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA
| | - Matthew Ulgherait
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA
| | - Clarice G Zhou
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA
| | - Elizabeth F Stone
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA
| | - Vanessa M Hill
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA
| | - Keith R Murphy
- Department of Metabolism and Aging, Scripps Research Institute, Jupiter, FL 33458, USA
| | - Julie C Canman
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - William W Ja
- Department of Metabolism and Aging, Scripps Research Institute, Jupiter, FL 33458, USA
| | - Mimi M Shirasu-Hiza
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA.
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40
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Abstract
The Target Of Rapamycin (TOR) is an evolutionarily conserved protein kinase that forms 2 distinct protein complexes referred to as TOR complex 1 (TORC1) and 2 (TORC2). Recent extensive studies have demonstrated that TORC1 is under the control of the small GTPases Rheb and Rag that funnel multiple input signals including those derived from nutritional sources; however, information is scarce as to the regulation of TORC2. A previous study using the model system provided by the fission yeast Schizosaccharomyces pombe identified Ryh1, a Rab-family GTPase, as an activator of TORC2. Here, we show that the nucleotide-binding state of Ryh1 is regulated in response to glucose, mediating this major nutrient signal to TORC2. In glucose-rich growth media, the GTP-bound form of Ryh1 induces TORC2-dependent phosphorylation of Gad8, a downstream target of TORC2 in fission yeast. Upon glucose deprivation, Ryh1 becomes inactive, which turns off the TORC2-Gad8 pathway. During glucose starvation, however, Gad8 phosphorylation by TORC2 gradually recovers independently of Ryh1, implying an additional TORC2 activator that is regulated negatively by glucose. The paired positive and negative regulatory mechanisms may allow fine-tuning of the TORC2-Gad8 pathway, which is essential for growth under glucose-limited environment.
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Affiliation(s)
- Tomoyuki Hatano
- a Graduate School of Biological Sciences , Nara Institute of Science and Technology , Ikoma , Nara , Japan
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41
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Kim TH, Kim MK, Cheong YH, Chae YN, Lee Y, Ka SO, Jung IH, Shin CY, Bae EJ, Son MH. Hepatic role in an early glucose-lowering effect by a novel dipeptidyl peptidase 4 inhibitor, evogliptin, in a rodent model of type 2 diabetes. Eur J Pharmacol 2015; 771:65-76. [PMID: 26621343 DOI: 10.1016/j.ejphar.2015.11.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 11/13/2015] [Accepted: 11/18/2015] [Indexed: 01/13/2023]
Abstract
Although multiple dipeptidyl peptidase 4 (DPP4) inhibitors have shown glucose-lowering effects by preserving pancreatic cells in high-fat diet (HFD)/streptozotocin (STZ)-induced diabetic mice, the hepatic role in regulation of glucose homeostasis by DPP4 inhibitors in HFD/STZ mice remains elusive. In herein study, parallel comparison of effects on the liver (expression of gluconeogenic genes and the linked signaling molecules) and pancreas (islet morphology and relative area of alpha or beta cells) in combination with glucose-lowering effects were made at the end of 2- and 10-week of evogliptin treatment in HFD/STZ mice. Significant control of hyperglycemia was observed from the second week and persisted during 10-week treatment of 0.3% evogliptin in HFD/STZ mice. This effect was accompanied by increased level of plasma glucagon-like peptide-1 and preserved pancreas islet structure. Furthermore, the hepatic increases in gluconeogenic gene expression in HFD/STZ mice was significantly reduced by evogliptin treatment, which was accompanied by the suppression of cAMP response element-binding protein (CREB) phosphorylation and expression of transducer of regulated CREB protein 2. This hepatic effect of evogliptin treatment was reproduced in 2-week study, however, pancreatic beta-cell area was not altered yet although the expression of pancreatic and duodenal homeobox protein 1 was increased. We conclude that the suppression of hepatic gluconeogenesis by evogliptin is followed by preservation of pancreatic islet, leading to remarkable and persistent glucose-lowering effect in HFD/STZ mice. Our findings provide further insight for the hepatic role in DPP4 inhibitor-mediated glucose control in diabetes.
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Affiliation(s)
- Tae-Hyoung Kim
- Drug Discovery Research Laboratories, Dong-A ST Research Institute, #21 Geumhwa-ro, 105Beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do 446-905, Republic of Korea
| | - Mi-Kyung Kim
- Drug Discovery Research Laboratories, Dong-A ST Research Institute, #21 Geumhwa-ro, 105Beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do 446-905, Republic of Korea
| | - Ye-Hwang Cheong
- Drug Discovery Research Laboratories, Dong-A ST Research Institute, #21 Geumhwa-ro, 105Beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do 446-905, Republic of Korea
| | - Yu-Na Chae
- Drug Discovery Research Laboratories, Dong-A ST Research Institute, #21 Geumhwa-ro, 105Beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do 446-905, Republic of Korea
| | - Youngyi Lee
- College of Pharmacy, Woosuk University, Wanju-gun, Jeollabuk-do, Republic of Korea
| | - Sun-O Ka
- Chonbuk National University Medical School, Jeonju-si, Jeollabuk-do, Republic of Korea
| | - Il-Hoon Jung
- Drug Discovery Research Laboratories, Dong-A ST Research Institute, #21 Geumhwa-ro, 105Beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do 446-905, Republic of Korea
| | - Chang-Yell Shin
- Drug Discovery Research Laboratories, Dong-A ST Research Institute, #21 Geumhwa-ro, 105Beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do 446-905, Republic of Korea
| | - Eun Ju Bae
- College of Pharmacy, Woosuk University, Wanju-gun, Jeollabuk-do, Republic of Korea.
| | - Moon-Ho Son
- Drug Discovery Research Laboratories, Dong-A ST Research Institute, #21 Geumhwa-ro, 105Beon-gil, Giheung-gu, Yongin-si, Gyeonggi-do 446-905, Republic of Korea.
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Abstract
The conserved target of rapamycin (TOR) kinase is a central regulator of cell growth in response to nutrient availability. TOR forms 2 structurally and functionally distinct complexes, TORC1 and TORC2, and negatively regulates autophagy via TORC1. Here we demonstrate TOR also operates independently through the TORC2 signaling pathway to promote autophagy upon amino acid limitation. Under these conditions, TORC2, through its downstream target kinase Ypk1, inhibits the Ca(2+)- and Cmd1/calmodulin-dependent phosphatase, calcineurin, to enable the activation of the amino acid-sensing EIF2S1/eIF2α kinase, Gcn2, and promote autophagy. Thus TORC2 signaling regulates autophagy in a pathway distinct from TORC1 to provide a tunable response to the cellular metabolic state.
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Affiliation(s)
- Ariadne Vlahakis
- a Department of Molecular and Cellular Biology; College of Biological Sciences ; University of California, Davis ; Davis , CA USA
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Powles T, Wheater M, Din O, Geldart T, Boleti E, Stockdale A, Sundar S, Robinson A, Ahmed I, Wimalasingham A, Burke W, Sarker SJ, Hussain S, Ralph C. A Randomised Phase 2 Study of AZD2014 Versus Everolimus in Patients with VEGF-Refractory Metastatic Clear Cell Renal Cancer. Eur Urol 2015; 69:450-6. [PMID: 26364551 DOI: 10.1016/j.eururo.2015.08.035] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Accepted: 08/24/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Everolimus is a mammalian target of rapamycin (mTOR) inhibitor used in vascular endothelial growth factor (VEGF)-refractory metastatic renal cell carcinoma (mRCC). It acts on only part of the mTOR complex (TORC1 alone). In vitro data support the use of mTOR inhibitors with broader activity (TORC1 and TORC2). OBJECTIVE The purpose of this study was to determine whether combined TORC1 and TORC2 inhibition with AZD2014 has superior activity to everolimus in VEGF-refractory clear cell mRCC. DESIGN, SETTING, AND PARTICIPANTS Patients with measurable mRCC and VEGF-refractory disease were eligible for this trial. INTERVENTION Starting in February 2013, patients were randomised (1:1) to AZD2014 (50 mg twice daily) or everolimus (10 mg once daily) until progression of disease at 10 centres across the United Kingdom. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Progression-free survival (PFS) was the primary end point and was compared using the stratified log-rank test. Secondary end points included tolerability, response rates, overall survival (OS), and pharmacokinetics (PK) analysis. The study was planned to recruit 120 patients. RESULTS AND LIMITATIONS Recruitment into the trial was stopped early (June 2014) due to lack of efficacy of AZD2014. At that point, 49 patients were randomised (26 to AZD2014 and 23 to everolimus). The PFS for AZD2014 and everolimus was 1.8 and 4.6 mo, respectively (hazard ratio: 2.8 [95% confidence interval (CI), 1.2-6.5]; p=0.01). Progression of disease as the best response to therapy was 69% for AZD2014 and 13% for everolimus (p<0.001). Grade 3-4 adverse events (AEs) occurred in 35% of AZD2014 and 48% of everolimus patients (p=0.3). Only 4% of patients stopped AZD2014 due to AEs. PK analysis suggested concentrations of AZD2014 were compatible with the therapeutic range. Final stratified OS hazard ratio at the time of trial closure (January 2015) was 3.1 (95% CI, 1.1-8.4; p<0.02). CONCLUSIONS The PFS and OS of AZD2014 were inferior to everolimus in this setting despite acceptable AE and PK profiles. PATIENT SUMMARY There is a strong rationale for testing mTOR inhibitors with a broader spectrum of activity than everolimus in metastatic clear cell renal cell carcinoma. AZD2014 is such an agent, but in this study, it was inferior to everolimus despite its attractive toxicity profile.
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Affiliation(s)
- Thomas Powles
- Barts Cancer Institute, Experimental Cancer Medicine Centre, Barts Health, Queen Mary University of London, London, UK; The Royal Free NHS Foundation Trust, London, UK.
| | | | - Omar Din
- Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | | | | | | | | | | | | | - Akhila Wimalasingham
- Barts Cancer Institute, Experimental Cancer Medicine Centre, Barts Health, Queen Mary University of London, London, UK
| | - Wendy Burke
- AstraZeneca UK Limited, Quantitative Clinical Pharmacology, Macclesfield, UK
| | - Shah-Jalal Sarker
- Barts Cancer Institute, Experimental Cancer Medicine Centre, Barts Health, Queen Mary University of London, London, UK
| | - Syed Hussain
- University of Liverpool, Clatterbridge Cancer Centre, Liverpool, UK
| | - Christy Ralph
- St. James's University Hospital, University of Leeds, Leeds, UK
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Kabeche R, Madrid M, Cansado J, Moseley JB. Eisosomes Regulate Phosphatidylinositol 4,5-Bisphosphate (PI(4,5)P2) Cortical Clusters and Mitogen-activated Protein (MAP) Kinase Signaling upon Osmotic Stress. J Biol Chem 2015; 290:25960-73. [PMID: 26359496 DOI: 10.1074/jbc.m115.674192] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Indexed: 01/22/2023] Open
Abstract
Eisosomes are multiprotein structures that generate linear invaginations at the plasma membrane of yeast cells. The core component of eisosomes, the BAR domain protein Pil1, generates these invaginations through direct binding to lipids including phosphoinositides. Eisosomes promote hydrolysis of phosphatidylinositol 4,5 bisphosphate (PI(4,5)P2) by functioning with synaptojanin, but the cellular processes regulated by this pathway have been unknown. Here, we found that PI(4,5)P2 regulation by eisosomes inhibits the cell integrity pathway, a conserved MAPK signal transduction cascade. This pathway is activated by multiple environmental conditions including osmotic stress in the fission yeast Schizosaccharomyces pombe. Activation of the MAPK Pmk1 was impaired by mutations in the phosphatidylinositol (PI) 5-kinase Its3, but this defect was suppressed by removal of eisosomes. Using fluorescent biosensors, we found that osmotic stress induced the formation of PI(4,5)P2 clusters that were spatially organized by eisosomes in both fission yeast and budding yeast cells. These cortical clusters contained the PI 5-kinase Its3 and did not assemble in the its3-1 mutant. The GTPase Rho2, an upstream activator of Pmk1, also co-localized with PI(4,5)P2 clusters under osmotic stress, providing a molecular link between these novel clusters and MAPK activation. Our findings have revealed that eisosomes regulate activation of MAPK signal transduction through the organization of cortical lipid-based microdomains.
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Affiliation(s)
- Ruth Kabeche
- From the Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755 and
| | - Marisa Madrid
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071, Murcia, Spain
| | - José Cansado
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071, Murcia, Spain
| | - James B Moseley
- From the Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755 and
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45
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Jiang SJ, Dong H, Li JB, Xu LJ, Zou X, Wang KF, Lu FE, Yi P. Berberine inhibits hepatic gluconeogenesis via the LKB1-AMPK- TORC2 signaling pathway in streptozotocin-induced diabetic rats. World J Gastroenterol 2015; 21:7777-7785. [PMID: 26167077 PMCID: PMC4491964 DOI: 10.3748/wjg.v21.i25.7777] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 02/14/2015] [Accepted: 03/31/2015] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the molecular mechanisms of berberine inhibition of hepatic gluconeogenesis in a diabetic rat model.
METHODS: The 40 rats were randomly divided into five groups. One group was selected as the normal group. In the remaining groups (n = 8 each), the rats were fed on a high-fat diet for 1 mo and received intravenous injection of streptozotocin for induction of the diabetic models. Berberine (156 mg/kg per day) (berberine group) or metformin (184 mg/kg per day) (metformin group) was intragastrically administered to the diabetic rats and 5-aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR) (0.5 mg/kg per day) (AICAR group) was subcutaneously injected to the diabetic rats for 12 wk. The remaining eight diabetic rats served as the model group. Fasting plasma glucose and insulin levels as well as lipid profile were tested. The expressions of proteins were examined by western blotting. The nuclear translocation of CREB-regulated transcription co-activator (TORC)2 was observed by immunohistochemical staining.
RESULTS: Berberine improved impaired glucose tolerance and decreased plasma hyperlipidemia. Moreover, berberine decreased fasting plasma insulin and homeostasis model assessment of insulin resistance (HOMA-IR). Berberine upregulated protein expression of liver kinase (LK)B1, AMP-activated protein kinase (AMPK) and phosphorylated AMPK (p-AMPK). The level of phophorylated TORC2 (p-TORC2) protein in the cytoplasm was higher in the berberine group than in the model group, and no significant difference in total TORC2 protein level was observed. Immunohistochemical staining revealed that more TORC2 was localized in the cytoplasm of the berberine group than in the model group. Moreover, berberine treatment downregulated protein expression of the key gluconeogenic enzymes (phosphoenolpyruvate carboxykinase and glucose-6-phosphatase) in the liver tissues.
CONCLUSION: Our findings revealed that berberine inhibited hepatic gluconeogenesis via the regulation of the LKB1-AMPK-TORC2 signaling pathway.
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Jevtov I, Zacharogianni M, van Oorschot MM, van Zadelhoff G, Aguilera-Gomez A, Vuillez I, Braakman I, Hafen E, Stocker H, Rabouille C. TORC2 mediates the heat stress response in Drosophila by promoting the formation of stress granules. J Cell Sci 2015; 128:2497-508. [PMID: 26054799 PMCID: PMC4510851 DOI: 10.1242/jcs.168724] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 06/03/2015] [Indexed: 12/29/2022] Open
Abstract
The kinase TOR is found in two complexes, TORC1, which is involved in growth control, and TORC2, whose roles are less well defined. Here, we asked whether TORC2 has a role in sustaining cellular stress. We show that TORC2 inhibition in Drosophila melanogaster leads to a reduced tolerance to heat stress, whereas sensitivity to other stresses is not affected. Accordingly, we show that upon heat stress, both in the animal and Drosophila cultured S2 cells, TORC2 is activated and is required for maintaining the level of its known target, Akt1 (also known as PKB). We show that the phosphorylation of the stress-activated protein kinases is not modulated by TORC2 nor is the heat-induced upregulation of heat-shock proteins. Instead, we show, both in vivo and in cultured cells, that TORC2 is required for the assembly of heat-induced cytoprotective ribonucleoprotein particles, the pro-survival stress granules. These granules are formed in response to protein translation inhibition imposed by heat stress that appears to be less efficient in the absence of TORC2 function. We propose that TORC2 mediates heat resistance in Drosophila by promoting the cell autonomous formation of stress granules.
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Affiliation(s)
- Irena Jevtov
- Institute of Molecular Systems Biology, ETH Zurich, Zurich 8093, Switzerland
| | | | - Marinke M van Oorschot
- Hubrecht Institute of the KNAW and UMC Utrecht, Uppsalalaan 8, Utrecht 3584 CT, Netherlands
| | - Guus van Zadelhoff
- Cellular Protein Chemistry, Utrecht University, Padualaan 8, Utrecht 3584 CH, The Netherlands
| | | | - Igor Vuillez
- Institute of Molecular Systems Biology, ETH Zurich, Zurich 8093, Switzerland
| | - Ineke Braakman
- Cellular Protein Chemistry, Utrecht University, Padualaan 8, Utrecht 3584 CH, The Netherlands
| | - Ernst Hafen
- Institute of Molecular Systems Biology, ETH Zurich, Zurich 8093, Switzerland
| | - Hugo Stocker
- Institute of Molecular Systems Biology, ETH Zurich, Zurich 8093, Switzerland
| | - Catherine Rabouille
- Hubrecht Institute of the KNAW and UMC Utrecht, Uppsalalaan 8, Utrecht 3584 CT, Netherlands Department of Cell Biology, UMC Utrecht, Heidelberglaan 100, Utrecht 3584 CX, The Netherlands
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47
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Caraveo G, Auluck PK, Whitesell L, Chung CY, Baru V, Mosharov EV, Yan X, Ben-Johny M, Soste M, Picotti P, Kim H, Caldwell KA, Caldwell GA, Sulzer D, Yue DT, Lindquist S. Calcineurin determines toxic versus beneficial responses to α-synuclein. Proc Natl Acad Sci U S A 2014; 111:E3544-52. [PMID: 25122673 DOI: 10.1073/pnas.1413201111] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Calcineurin (CN) is a highly conserved Ca(2+)-calmodulin (CaM)-dependent phosphatase that senses Ca(2+) concentrations and transduces that information into cellular responses. Ca(2+) homeostasis is disrupted by α-synuclein (α-syn), a small lipid binding protein whose misfolding and accumulation is a pathological hallmark of several neurodegenerative diseases. We report that α-syn, from yeast to neurons, leads to sustained highly elevated levels of cytoplasmic Ca(2+), thereby activating a CaM-CN cascade that engages substrates that result in toxicity. Surprisingly, complete inhibition of CN also results in toxicity. Limiting the availability of CaM shifts CN's spectrum of substrates toward protective pathways. Modulating CN or CN's substrates with highly selective genetic and pharmacological tools (FK506) does the same. FK506 crosses the blood brain barrier, is well tolerated in humans, and is active in neurons and glia. Thus, a tunable response to CN, which has been conserved for a billion years, can be targeted to rebalance the phosphatase's activities from toxic toward beneficial substrates. These findings have immediate therapeutic implications for synucleinopathies.
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48
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Abstract
The inhibition of the central growth regulatory kinase TOR, which participates in two complexes, TORC1 and TORC2, has been a focus of metabolic and cancer studies for many years. Most studies have dealt with TORC1, the canonical target of rapamycin, and the role of this complex in autophagy, protein synthesis, and cell growth control. Recent work on TORC2 in budding and fission yeast species points to a conserved role of this lesser-known TOR complex in the survival of DNA damage. In budding yeast, TORC2 controls lipid biosynthesis and actin cytoskeleton through downstream AGC kinases, which are now, surprisingly, implicated in the survival of oxidative DNA damage. Preliminary data from mTORC2 modulation in cancer cells suggest that an extension to human chemotherapy is worth exploring.
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Affiliation(s)
- Ronit Weisman
- Department of Natural and Life Sciences, The Open University of Israel, Raanana, Israel
| | - Adiel Cohen
- Department of Natural and Life Sciences, The Open University of Israel, Raanana, Israel
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
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49
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Cohen A, Kupiec M, Weisman R. Glucose activates TORC2-Gad8 protein via positive regulation of the cAMP/cAMP-dependent protein kinase A (PKA) pathway and negative regulation of the Pmk1 protein-mitogen-activated protein kinase pathway. J Biol Chem 2014; 289:21727-37. [PMID: 24928510 DOI: 10.1074/jbc.m114.573824] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The target of rapamycin (TOR) kinase belongs to the highly conserved eukaryotic family of phosphatidylinositol 3-kinase-related kinases. TOR proteins are found at the core of two evolutionary conserved complexes, known as TORC1 and TORC2. In fission yeast, TORC2 is dispensable for proliferation under optimal growth conditions but is required for starvation and stress responses. TORC2 has been implicated in a wide variety of functions; however, the signals that regulate TORC2 activity have so far remained obscure. TORC2 has one known direct substrate, the AGC kinase Gad8, which is related to AKT in human cells. Gad8 is phosphorylated by TORC2 at Ser-546 (equivalent to AKT Ser-473), leading to its activation. Here, we show that glucose is necessary and sufficient to induce Gad8 Ser-546 phosphorylation in vivo and Gad8 kinase activity in vitro. The glucose signal that activates TORC2-Gad8 is mediated via the cAMP/PKA pathway, a major glucose-sensing pathway. By contrast, Pmk1, similar to human extracellular signal-regulated kinases and a major stress-induced mitogen activated protein kinase (MAPK) in fission yeast, inhibits TORC2-dependent Gad8 phosphorylation and activation. Inhibition of TORC2-Gad8 also occurs in response to ionic or osmotic stress, in a manner dependent on the cAMP/PKA and Pmk1-MAPK signaling pathways. Our findings highlight the significance of glucose availability in regulation of TORC2-Gad8 and indicate a novel link between the cAMP/PKA, Pmk1/MAPK, and TORC2-Gad8 signaling.
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Affiliation(s)
- Adiel Cohen
- From the Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana and
| | - Martin Kupiec
- the Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Ronit Weisman
- From the Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana and
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50
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Abstract
Stable compartments of the plasma membrane promote a wide range of cellular functions. In yeast cells, cytosolic structures called eisosomes generate prominent cortical invaginations of unknown function. Through a series of genetic screens in fission yeast, we found that the eisosome proteins Pil1 and Sle1 function with the synaptojanin-like lipid phosphatase Syj1 and its ligand Tax4. This genetic pathway connects eisosome function with the hydrolysis of phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] in cells. Defects in PI(4,5)P2 regulation led to eisosome defects, and we found that the core eisosome protein Pil1 can bind to and tubulate liposomes containing PI(4,5)P2. Mutations in components of the Pil1-Sle1-Syj1-Tax4 pathway suppress the growth and morphology defects of TORC2 mutants, indicating that eisosome-dependent regulation of PI(4,5)P2 feeds into signal transduction pathways. We propose that the geometry of membrane invaginations generates spatial and temporal signals for lipid-mediated signaling events in cells.
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Affiliation(s)
- Ruth Kabeche
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
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