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Moors TE, Morella ML, Bertran-Cobo C, Geut H, Udayar V, Timmermans-Huisman E, Ingrassia AMT, Brevé JJP, Bol JGJM, Bonifati V, Jagasia R, van de Berg WDJ. Altered TFEB subcellular localization in nigral neurons of subjects with incidental, sporadic and GBA-related Lewy body diseases. Acta Neuropathol 2024; 147:67. [PMID: 38581586 PMCID: PMC10998821 DOI: 10.1007/s00401-024-02707-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 02/14/2024] [Accepted: 02/14/2024] [Indexed: 04/08/2024]
Abstract
Transcription factor EB (TFEB) is a master regulator of genes involved in the maintenance of autophagic and lysosomal homeostasis, processes which have been implicated in the pathogenesis of GBA-related and sporadic Parkinson's disease (PD), and dementia with Lewy bodies (DLB). TFEB activation results in its translocation from the cytosol to the nucleus. Here, we investigated TFEB subcellular localization and its relation to intracellular alpha-synuclein (aSyn) accumulation in post-mortem human brain of individuals with either incidental Lewy body disease (iLBD), GBA-related PD/DLB (GBA-PD/DLB) or sporadic PD/DLB (sPD/DLB), compared to control subjects. We analyzed nigral dopaminergic neurons using high-resolution confocal and stimulated emission depletion (STED) microscopy and semi-quantitatively scored the TFEB subcellular localization patterns. We observed reduced nuclear TFEB immunoreactivity in PD/DLB patients compared to controls, both in sporadic and GBA-related cases, as well as in iLBD cases. Nuclear depletion of TFEB was more pronounced in neurons with Ser129-phosphorylated (pSer129) aSyn accumulation in all groups. Importantly, we observed previously-unidentified TFEB-immunopositive perinuclear clusters in human dopaminergic neurons, which localized at the Golgi apparatus. These TFEB clusters were more frequently observed and more severe in iLBD, sPD/DLB and GBA-PD/DLB compared to controls, particularly in pSer129 aSyn-positive neurons, but also in neurons lacking detectable aSyn accumulation. In aSyn-negative cells, cytoplasmic TFEB clusters were more frequently observed in GBA-PD/DLB and iLBD patients, and correlated with reduced GBA enzymatic activity as well as increased Braak LB stage. Altered TFEB distribution was accompanied by a reduction in overall mRNA expression levels of selected TFEB-regulated genes, indicating a possible early dysfunction of lysosomal regulation. Overall, we observed cytoplasmic TFEB retention and accumulation at the Golgi in cells without apparent pSer129 aSyn accumulation in iLBD and PD/DLB patients. This suggests potential TFEB impairment at the early stages of cellular disease and underscores TFEB as a promising therapeutic target for synucleinopathies.
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Affiliation(s)
- Tim E Moors
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Martino L Morella
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Cesc Bertran-Cobo
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Hanneke Geut
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Vinod Udayar
- Roche Pharma Research and Early Development; Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center, Basel, Switzerland
| | - Evelien Timmermans-Huisman
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Angela M T Ingrassia
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - John J P Brevé
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - John G J M Bol
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands
| | - Vincenzo Bonifati
- Erasmus MC, Department of Clinical Genetics, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Ravi Jagasia
- Roche Pharma Research and Early Development; Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center, Basel, Switzerland
| | - Wilma D J van de Berg
- Section Clinical Neuroanatomy and Biobanking, Department of Anatomy and Neurosciences, Amsterdam UMC, Vrije University, Amsterdam, The Netherlands.
- Amsterdam Neuroscience, Program Neurodegeneration, Amsterdam, The Netherlands.
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Maji S, Pirozzi M, Ruturaj, Pandey R, Ghosh T, Das S, Gupta A. Copper-independent lysosomal localisation of the Wilson disease protein ATP7B. Traffic 2023; 24:587-609. [PMID: 37846526 DOI: 10.1111/tra.12919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 09/10/2023] [Accepted: 09/23/2023] [Indexed: 10/18/2023]
Abstract
In hepatocytes, the Wilson disease protein ATP7B resides on the trans-Golgi network (TGN) and traffics to peripheral lysosomes to export excess intracellular copper through lysosomal exocytosis. We found that in basal copper or even upon copper chelation, a significant amount of ATP7B persists in the endolysosomal compartment of hepatocytes but not in non-hepatic cells. These ATP7B-harbouring lysosomes lie in close proximity of ~10 nm to the TGN. ATP7B constitutively distributes itself between the sub-domain of the TGN with a lower pH and the TGN-proximal lysosomal compartments. The presence of ATP7B on TGN-lysosome colocalising sites upon Golgi disruption suggested a possible exchange of ATP7B directly between the TGN and its proximal lysosomes. Manipulating lysosomal positioning significantly alters the localisation of ATP7B in the cell. Contrary to previous understanding, we found that upon copper chelation in a copper-replete hepatocyte, ATP7B is not retrieved back to TGN from peripheral lysosomes; rather, ATP7B recycles to these TGN-proximal lysosomes to initiate the next cycle of copper transport. We report a hitherto unknown copper-independent lysosomal localisation of ATP7B and the importance of TGN-proximal lysosomes but not TGN as the terminal acceptor organelle of ATP7B in its retrograde pathway.
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Affiliation(s)
- Saptarshi Maji
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India
| | | | - Ruturaj
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India
| | - Raviranjan Pandey
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India
| | - Tamal Ghosh
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India
| | - Santanu Das
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India
| | - Arnab Gupta
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India
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3
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Wang L, Klionsky DJ, Shen HM. The emerging mechanisms and functions of microautophagy. Nat Rev Mol Cell Biol 2023; 24:186-203. [PMID: 36097284 DOI: 10.1038/s41580-022-00529-z] [Citation(s) in RCA: 107] [Impact Index Per Article: 107.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2022] [Indexed: 02/08/2023]
Abstract
'Autophagy' refers to an evolutionarily conserved process through which cellular contents, such as damaged organelles and protein aggregates, are delivered to lysosomes for degradation. Different forms of autophagy have been described on the basis of the nature of the cargoes and the means used to deliver them to lysosomes. At present, the prevailing categories of autophagy in mammalian cells are macroautophagy, microautophagy and chaperone-mediated autophagy. The molecular mechanisms and biological functions of macroautophagy and chaperone-mediated autophagy have been extensively studied, but microautophagy has received much less attention. In recent years, there has been a growth in research on microautophagy, first in yeast and then in mammalian cells. Here we review this form of autophagy, focusing on selective forms of microautophagy. We also discuss the upstream regulatory mechanisms, the crosstalk between macroautophagy and microautophagy, and the functional implications of microautophagy in diseases such as cancer and neurodegenerative disorders in humans. Future research into microautophagy will provide opportunities to develop novel interventional strategies for autophagy- and lysosome-related diseases.
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Affiliation(s)
- Liming Wang
- School of Biomedical Sciences, Hunan University, Changsha, China
| | - Daniel J Klionsky
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
| | - Han-Ming Shen
- Faculty of Health Sciences, Ministry of Education Frontiers Science Center for Precision Oncology, University of Macau, Macau, China. .,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
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4
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New Insights into the Regulation of mTOR Signaling via Ca 2+-Binding Proteins. Int J Mol Sci 2023; 24:ijms24043923. [PMID: 36835331 PMCID: PMC9959742 DOI: 10.3390/ijms24043923] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Environmental factors are important regulators of cell growth and proliferation. Mechanistic target of rapamycin (mTOR) is a central kinase that maintains cellular homeostasis in response to a variety of extracellular and intracellular inputs. Dysregulation of mTOR signaling is associated with many diseases, including diabetes and cancer. Calcium ion (Ca2+) is important as a second messenger in various biological processes, and its intracellular concentration is tightly regulated. Although the involvement of Ca2+ mobilization in mTOR signaling has been reported, the detailed molecular mechanisms by which mTOR signaling is regulated are not fully understood. The link between Ca2+ homeostasis and mTOR activation in pathological hypertrophy has heightened the importance in understanding Ca2+-regulated mTOR signaling as a key mechanism of mTOR regulation. In this review, we introduce recent findings on the molecular mechanisms of regulation of mTOR signaling by Ca2+-binding proteins, particularly calmodulin (CaM).
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Patra S, Patil S, Klionsky DJ, Bhutia SK. Lysosome signaling in cell survival and programmed cell death for cellular homeostasis. J Cell Physiol 2023; 238:287-305. [PMID: 36502521 DOI: 10.1002/jcp.30928] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/06/2022] [Accepted: 11/24/2022] [Indexed: 12/14/2022]
Abstract
Recent developments in lysosome biology have transformed our view of lysosomes from static garbage disposals that can also act as suicide bags to decidedly dynamic multirole adaptive operators of cellular homeostasis. Lysosome-governed signaling pathways, proteins, and transcription factors equilibrate the rate of catabolism and anabolism (autophagy to lysosomal biogenesis and metabolite pool maintenance) by sensing cellular metabolic status. Lysosomes also interact with other organelles by establishing contact sites through which they exchange cellular contents. Lysosomal function is critically assessed by lysosomal positioning and motility for cellular adaptation. In this setting, mechanistic target of rapamycin kinase (MTOR) is the chief architect of lysosomal signaling to control cellular homeostasis. Notably, lysosomes can orchestrate explicit cell death mechanisms, such as autophagic cell death and lysosomal membrane permeabilization-associated regulated necrotic cell death, to maintain cellular homeostasis. These lines of evidence emphasize that the lysosomes serve as a central signaling hub for cellular homeostasis.
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Affiliation(s)
- Srimanta Patra
- Cancer and Cell Death Laboratory, Department of Life Science, National Institute of Technology, Rourkela, Odisha, India
| | - Shankargouda Patil
- Division of Oral Pathology, Department of Maxillofacial Surgery and Diagnostic Sciences, College of Dentistry, Jazan University, Jazan, Saudi Arabia
| | - Daniel J Klionsky
- Department of Molecular, Cellular and Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Sujit K Bhutia
- Cancer and Cell Death Laboratory, Department of Life Science, National Institute of Technology, Rourkela, Odisha, India
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6
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Cross-linking of the endolysosomal system reveals potential flotillin structures and cargo. Nat Commun 2022; 13:6212. [PMID: 36266287 PMCID: PMC9584938 DOI: 10.1038/s41467-022-33951-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 10/06/2022] [Indexed: 12/24/2022] Open
Abstract
Lysosomes are well-established as the main cellular organelles for the degradation of macromolecules and emerging as regulatory centers of metabolism. They are of crucial importance for cellular homeostasis, which is exemplified by a plethora of disorders related to alterations in lysosomal function. In this context, protein complexes play a decisive role, regulating not only metabolic lysosomal processes but also lysosome biogenesis, transport, and interaction with other organelles. Using cross-linking mass spectrometry, we analyze lysosomes and early endosomes. Based on the identification of 5376 cross-links, we investigate protein-protein interactions and structures of lysosome- and endosome-related proteins. In particular, we present evidence for a tetrameric assembly of the lysosomal hydrolase PPT1 and a heterodimeric structure of FLOT1/FLOT2 at lysosomes and early endosomes. For FLOT1-/FLOT2-positive early endosomes, we identify >300 putative cargo proteins and confirm eleven substrates for flotillin-dependent endocytosis, including the latrophilin family of adhesion G protein-coupled receptors.
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Liu F, Tian T, Zhang Z, Xie S, Yang J, Zhu L, Wang W, Shi C, Sang L, Guo K, Yang Z, Qu L, Liu X, Liu J, Yan Q, Ju HQ, Wang W, Piao HL, Shao J, Zhou T, Lin A. Long non-coding RNA SNHG6 couples cholesterol sensing with mTORC1 activation in hepatocellular carcinoma. Nat Metab 2022; 4:1022-1040. [PMID: 35995997 DOI: 10.1038/s42255-022-00616-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 07/01/2022] [Indexed: 02/06/2023]
Abstract
Cholesterol contributes to the structural basis of biological membranes and functions as a signaling molecule, whose dysregulation has been associated with various human diseases. Here, we report that the long non-coding RNA (lncRNA) SNHG6 increases progression from non-alcoholic fatty liver disease (NAFLD) to hepatocellular carcinoma (HCC) by modulating cholesterol-induced mTORC1 activation. Mechanistically, cholesterol binds ER-anchored FAF2 protein to promote the formation of a SNHG6-FAF2-mTOR complex. As a putative cholesterol effector, SNHG6 enhances cholesterol-dependent mTORC1 lysosomal recruitment and activation via enhancing FAF2-mTOR interaction at ER-lysosome contacts, thereby coordinating mTORC1 kinase cascade activation with cellular cholesterol biosynthesis in a self-amplified cycle to accelerate cholesterol-driven NAFLD-HCC development. Notably, loss of SNHG6 inhibits mTORC1 signaling and impairs growth of patient-derived xenograft liver cancer tumors, identifyifng SNHG6 as a potential target for liver cancer treatment. Together, our findings illustrate the crucial role of organelle-associated lncRNA in organelle communication, nutrient sensing, and kinase cascades.
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Affiliation(s)
- Fangzhou Liu
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
- Cancer Center, Zhejiang University, Hangzhou, China
- Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang, China
| | - Tian Tian
- Department of Medical Biochemistry and Molecular Biology, School of Medicine, Jinan University, Guangzhou, China
| | - Zhen Zhang
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
- Cancer Center, Zhejiang University, Hangzhou, China
- Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang, China
| | - Shanshan Xie
- Cancer Center, Zhejiang University, Hangzhou, China
- Department of Cell Biology and Program in Molecular Cell Biology, Zhejiang University School of Medicine, Hangzhou, China
- Department of Gastroenterology, The Second Affiliated Hospital, School of Medicine and Institute of Gastroenterology, Zhejiang University, Hangzhou, China
| | - Jiecheng Yang
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Linyu Zhu
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Wen Wang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Chengyu Shi
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Lingjie Sang
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Kaiqiang Guo
- Fujian Provincial Key Laboratory of Innovative Drug Target Research and State Key Laboratory of Cellular Stress Biology, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Zuozhen Yang
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Lei Qu
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Xiangrui Liu
- Cancer Center, Zhejiang University, Hangzhou, China
- Department of Cell Biology and Program in Molecular Cell Biology, Zhejiang University School of Medicine, Hangzhou, China
- Department of Gastroenterology, The Second Affiliated Hospital, School of Medicine and Institute of Gastroenterology, Zhejiang University, Hangzhou, China
| | - Jian Liu
- Zhejiang University-University of Edinburgh Institute, Zhejiang University School of Medicine, Haining, China
| | - Qingfeng Yan
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Huai-Qiang Ju
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Wenqi Wang
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - Hai-Long Piao
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Jianzhong Shao
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Tianhua Zhou
- Cancer Center, Zhejiang University, Hangzhou, China.
- Department of Cell Biology and Program in Molecular Cell Biology, Zhejiang University School of Medicine, Hangzhou, China.
- Department of Gastroenterology, The Second Affiliated Hospital, School of Medicine and Institute of Gastroenterology, Zhejiang University, Hangzhou, China.
| | - Aifu Lin
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China.
- Cancer Center, Zhejiang University, Hangzhou, China.
- Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang, China.
- Breast Center of the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
- International School of Medicine, International Institutes of Medicine, The 4th Affiliated Hospital of Zhejiang University School of Medicine, Yiwu, China.
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Armijo ME, Escalona E, Peña D, Farias A, Morin V, Baumann M, Klebl BM, Pincheira R, Castro AF. Blocking the Farnesyl Pocket of PDEδ Reduces Rheb-Dependent mTORC1 Activation and Survival of Tsc2-Null Cells. Front Pharmacol 2022; 13:912688. [PMID: 35814251 PMCID: PMC9260180 DOI: 10.3389/fphar.2022.912688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 05/31/2022] [Indexed: 11/22/2022] Open
Abstract
Rheb is a small GTPase member of the Ras superfamily and an activator of mTORC1, a protein complex master regulator of cell metabolism, growth, and proliferation. Rheb/mTORC1 pathway is hyperactivated in proliferative diseases, such as Tuberous Sclerosis Complex syndrome and cancer. Therefore, targeting Rheb-dependent signaling is a rational strategy for developing new drug therapies. Rheb activates mTORC1 in the cytosolic surface of lysosomal membranes. Rheb’s farnesylation allows its anchorage on membranes, while its proper localization depends on the prenyl-binding chaperone PDEδ. Recently, the use of PDEδ inhibitors has been proposed as anticancer agents because they interrupted KRas signaling leading to antiproliferative effects in KRas-dependent pancreatic cancer cells. However, the effect of PDEδ inhibition on the Rheb/mTORC1 pathway has been poorly investigated. Here, we evaluated the impact of a new PDEδ inhibitor, called Deltasonamide 1, in Tsc2-null MEFs, a Rheb-dependent overactivated mTORC1 cell line. By using a yeast two-hybrid assay, we first validated that Deltasonamide 1 disrupts Rheb-PDEδ interaction. Accordingly, we found that Deltasonamide 1 reduces mTORC1 targets activation. In addition, our results showed that Deltasonamide 1 has antiproliferative and cytotoxic effects on Tsc2-null MEFs but has less effect on Tsc2-wild type MEFs viability. This work proposes the pharmacological PDEδ inhibition as a new approach to target the abnormal Rheb/mTORC1 activation in Tuberous Sclerosis Complex cells.
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Affiliation(s)
- Marisol Estrella Armijo
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
- Laboratorio de Investigación en Ciencias Biomédicas, Departamento de Ciencias Básicas y Morfología, Facultad de Medicina, Universidad Católica de la Santísima Concepción, Concepción, Chile
| | - Emilia Escalona
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Daniela Peña
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Alejandro Farias
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Violeta Morin
- Laboratorio de Proteasas y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | | | | | - Roxana Pincheira
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
- *Correspondence: Roxana Pincheira, ; Ariel Fernando Castro,
| | - Ariel Fernando Castro
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
- *Correspondence: Roxana Pincheira, ; Ariel Fernando Castro,
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Nuclear-targeted 4E-BP1 is dephosphorylated, induces nuclear translocation of eIF4E, and alters mRNA translation. Exp Cell Res 2022; 418:113246. [PMID: 35697076 DOI: 10.1016/j.yexcr.2022.113246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 06/02/2022] [Accepted: 06/04/2022] [Indexed: 11/23/2022]
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) phosphorylates and inhibits eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). This leads to the release of eIF4E from 4E-BP1 and the initiation of eIF4E-dependent mRNA translation. In this study, we examined the expression of a 4E-BP1-based reporter (mTORC1 activity reporter; TORCAR) with various localization signal tags to clarify the relationship between the localization of 4E-BP1 and its phosphorylation. Phosphorylation of 4E-BP1 at threonine 37/46 and serine 65 was efficient at lysosomes and the plasma membrane, whereas it was significantly decreased in the nucleus. In addition, the localization of endogenous eIF4E shifted from the cytoplasm to the nucleus only when nuclear-localized TORCAR was expressed. Nuclear-localized TORCAR decreased cyclin D1 protein levels and altered cell cycle distribution. These data provide an experimental tool to manipulate the localization of endogenous eIF4E without affecting mTORC1 and highlight the important role of nuclear-cytoplasmic shuttling of eIF4E.
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10
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Nowosad A, Besson A. Lysosomes at the Crossroads of Cell Metabolism, Cell Cycle, and Stemness. Int J Mol Sci 2022; 23:ijms23042290. [PMID: 35216401 PMCID: PMC8879101 DOI: 10.3390/ijms23042290] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/11/2022] [Accepted: 02/16/2022] [Indexed: 02/07/2023] Open
Abstract
Initially described as lytic bodies due to their degradative and recycling functions, lysosomes play a critical role in metabolic adaptation to nutrient availability. More recently, the contribution of lysosomal proteins to cell signaling has been established, and lysosomes have emerged as signaling hubs that regulate diverse cellular processes, including cell proliferation and cell fate. Deciphering these signaling pathways has revealed an extensive crosstalk between the lysosomal and cell cycle machineries that is only beginning to be understood. Recent studies also indicate that a number of lysosomal proteins are involved in the regulation of embryonic and adult stem cell fate and identity. In this review, we will focus on the role of the lysosome as a signaling platform with an emphasis on its function in integrating nutrient sensing with proliferation and cell cycle progression, as well as in stemness-related features, such as self-renewal and quiescence.
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Affiliation(s)
- Ada Nowosad
- Molecular, Cellular and Developmental Biology Department (MCD), Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062 Toulouse, France;
- Department of Oncology, KULeuven, Laboratory for Molecular Cancer Biology, Center for Cancer Biology, VIB, 3000 Leuven, Belgium
| | - Arnaud Besson
- Molecular, Cellular and Developmental Biology Department (MCD), Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062 Toulouse, France;
- Correspondence: ; Tel.: +33-561558486
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11
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Loissell-Baltazar YA, Dokudovskaya S. SEA and GATOR 10 Years Later. Cells 2021; 10:cells10102689. [PMID: 34685669 PMCID: PMC8534245 DOI: 10.3390/cells10102689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/30/2021] [Accepted: 10/03/2021] [Indexed: 12/17/2022] Open
Abstract
The SEA complex was described for the first time in yeast Saccharomyces cerevisiae ten years ago, and its human homologue GATOR complex two years later. During the past decade, many advances on the SEA/GATOR biology in different organisms have been made that allowed its role as an essential upstream regulator of the mTORC1 pathway to be defined. In this review, we describe these advances in relation to the identification of multiple functions of the SEA/GATOR complex in nutrient response and beyond and highlight the consequence of GATOR mutations in cancer and neurodegenerative diseases.
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12
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Fernandes SA, Demetriades C. The Multifaceted Role of Nutrient Sensing and mTORC1 Signaling in Physiology and Aging. FRONTIERS IN AGING 2021; 2:707372. [PMID: 35822019 PMCID: PMC9261424 DOI: 10.3389/fragi.2021.707372] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 08/12/2021] [Indexed: 01/10/2023]
Abstract
The mechanistic Target of Rapamycin (mTOR) is a growth-related kinase that, in the context of the mTOR complex 1 (mTORC1), touches upon most fundamental cellular processes. Consequently, its activity is a critical determinant for cellular and organismal physiology, while its dysregulation is commonly linked to human aging and age-related disease. Presumably the most important stimulus that regulates mTORC1 activity is nutrient sufficiency, whereby amino acids play a predominant role. In fact, mTORC1 functions as a molecular sensor for amino acids, linking the cellular demand to the nutritional supply. Notably, dietary restriction (DR), a nutritional regimen that has been shown to extend lifespan and improve healthspan in a broad spectrum of organisms, works via limiting nutrient uptake and changes in mTORC1 activity. Furthermore, pharmacological inhibition of mTORC1, using rapamycin or its analogs (rapalogs), can mimic the pro-longevity effects of DR. Conversely, nutritional amino acid overload has been tightly linked to aging and diseases, such as cancer, type 2 diabetes and obesity. Similar effects can also be recapitulated by mutations in upstream mTORC1 regulators, thus establishing a tight connection between mTORC1 signaling and aging. Although the role of growth factor signaling upstream of mTORC1 in aging has been investigated extensively, the involvement of signaling components participating in the nutrient sensing branch is less well understood. In this review, we provide a comprehensive overview of the molecular and cellular mechanisms that signal nutrient availability to mTORC1, and summarize the role that nutrients, nutrient sensors, and other components of the nutrient sensing machinery play in cellular and organismal aging.
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Affiliation(s)
- Stephanie A. Fernandes
- Max Planck Institute for Biology of Ageing (MPI-AGE), Cologne, Germany
- Cologne Graduate School for Ageing Research (CGA), Cologne, Germany
| | - Constantinos Demetriades
- Max Planck Institute for Biology of Ageing (MPI-AGE), Cologne, Germany
- Cologne Graduate School for Ageing Research (CGA), Cologne, Germany
- University of Cologne, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
- *Correspondence: Constantinos Demetriades,
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13
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Shimada R, Koike H, Hirano T, Kato Y, Saga Y. NANOS2 suppresses the cell cycle by repressing mTORC1 activators in embryonic male germ cells. iScience 2021; 24:102890. [PMID: 34401671 PMCID: PMC8350546 DOI: 10.1016/j.isci.2021.102890] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 06/15/2021] [Accepted: 07/16/2021] [Indexed: 12/25/2022] Open
Abstract
During murine germ cell development, male germ cells enter the mitotically arrested G0 stage, which is an initial step of sexually dimorphic differentiation. The male-specific RNA-binding protein NANOS2 has a key role in suppressing the cell cycle in germ cells. However, the detailed mechanism of how NANOS2 regulates the cell cycle remains unclear. Using single-cell RNA sequencing (scRNA-seq), we extracted the cell cycle state of each germ cell in wild-type and Nanos2-KO testes and revealed that Nanos2 expression starts in mitotic cells and induces mitotic arrest. We identified Rheb, a regulator of mTORC1, and Ptma as possible targets of NANOS2. We propose that repression of the cell cycle is a primary function of NANOS2 and that it is mediated via the suppression of mTORC1 activity through the repression of Rheb in a post-transcriptional manner.
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Affiliation(s)
- Ryuki Shimada
- Department of Genetics, SOKENDAI, Yata 1111, Mishima, Shizuoka 411-8540, Japan.,Mammalian Development Laboratory, Department of Gene Function and Phenomics, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Hiroko Koike
- Department of Genetics, SOKENDAI, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Takamasa Hirano
- Mammalian Development Laboratory, Department of Gene Function and Phenomics, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Yuzuru Kato
- Department of Genetics, SOKENDAI, Yata 1111, Mishima, Shizuoka 411-8540, Japan.,Mammalian Development Laboratory, Department of Gene Function and Phenomics, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Yumiko Saga
- Department of Genetics, SOKENDAI, Yata 1111, Mishima, Shizuoka 411-8540, Japan.,Mammalian Development Laboratory, Department of Gene Function and Phenomics, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan.,Division for the Development of Genetically Engineered Mouse Resources, Genetic Resource Center, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
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14
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Amino Acids in Autophagy: Regulation and Function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1332:51-66. [PMID: 34251638 DOI: 10.1007/978-3-030-74180-8_4] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Autophagy is a dynamic process in which the eukaryotic cells break down intracellular components by lysosomal degradation. Under the normal condition, the basal level of autophagy removes damaged organelles, misfolded proteins, or protein aggregates to keep cells in a homeostatic condition. Deprivation of nutrients (e.g., removal of amino acids) stimulates autophagy activity, promoting lysosomal degradation and the recycling of cellular components for cell survival. Importantly, insulin and amino acids are two main inhibitors of autophagy. They both activate the mTOR complex 1 (mTORC1) signaling pathway to inhibit the autophagy upstream of the uncoordinated-51 like kinase 1/2 (ULK1/2) complex that triggers autophagosome formation. In particular, insulin activates mTORC1 via the PI3K class I-AKT pathway; while amino acids activate mTORC1 either through the PI3K class III (hVps34) pathway or through a variety of amino acid sensors located in the cytosol or lysosomal membrane. These amino acid sensors control the translocation of mTORC1 from the cytosol to the lysosomal surface where mTORC1 is activated by Rheb GTPase, therefore regulating autophagy and the lysosomal protein degradation.
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15
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Amemiya Y, Nakamura N, Ikeda N, Sugiyama R, Ishii C, Maki M, Shibata H, Takahara T. Amino Acid-Mediated Intracellular Ca 2+ Rise Modulates mTORC1 by Regulating the TSC2-Rheb Axis through Ca 2+/Calmodulin. Int J Mol Sci 2021; 22:ijms22136897. [PMID: 34198993 PMCID: PMC8269083 DOI: 10.3390/ijms22136897] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 06/23/2021] [Indexed: 12/13/2022] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a master growth regulator by controlling protein synthesis and autophagy in response to environmental cues. Amino acids, especially leucine and arginine, are known to be important activators of mTORC1 and to promote lysosomal translocation of mTORC1, where mTORC1 is thought to make contact with its activator Rheb GTPase. Although amino acids are believed to exclusively regulate lysosomal translocation of mTORC1 by Rag GTPases, how amino acids increase mTORC1 activity besides regulation of mTORC1 subcellular localization remains largely unclear. Here we report that amino acids also converge on regulation of the TSC2-Rheb GTPase axis via Ca2+/calmodulin (CaM). We showed that the amino acid-mediated increase of intracellular Ca2+ is important for mTORC1 activation and thereby contributes to the promotion of nascent protein synthesis. We found that Ca2+/CaM interacted with TSC2 at its GTPase activating protein (GAP) domain and that a CaM inhibitor reduced binding of CaM with TSC2. The inhibitory effect of a CaM inhibitor on mTORC1 activity was prevented by loss of TSC2 or by an active mutant of Rheb GTPase, suggesting that a CaM inhibitor acts through the TSC2-Rheb axis to inhibit mTORC1 activity. Taken together, in response to amino acids, Ca2+/CaM-mediated regulation of the TSC2-Rheb axis contributes to proper mTORC1 activation, in addition to the well-known lysosomal translocation of mTORC1 by Rag GTPases.
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16
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Abstract
Mechanistic (or mammalian) target of rapamycin complex 1 (mTORC1) is a major signalling kinase in cells that regulates proliferation and metabolism and is controlled by extrinsic and intrinsic signals. The lysosome has received considerable attention as a major hub of mTORC1 activation. However, mTOR has also been located to a variety of other intracellular sites, indicating the possibility of spatial regulation of mTORC1 signalling within cells. In particular, there have been numerous recent reports of mTORC1 activation associated with the Golgi apparatus. Here, we review the evidence for the regulation of mTORC1 signalling at the Golgi in mammalian cells. mTORC1 signalling is closely linked to the morphology of the Golgi architecture; a number of Golgi membrane tethers/scaffolds that influence Golgi architecture in mammalian cells that directly or indirectly regulate mTORC1 activation have been identified. Perturbation of the Golgi mTORC1 pathway arising from fragmentation of the Golgi has been shown to promote oncogenesis. Here, we highlight the potential mechanisms for the activation mTORC1 at the Golgi, which is emerging as a major site for mTORC1 signalling.
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Affiliation(s)
- Christian Makhoul
- The Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Paul A Gleeson
- The Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
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17
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Morozumi Y, Shiozaki K. Conserved and Divergent Mechanisms That Control TORC1 in Yeasts and Mammals. Genes (Basel) 2021; 12:genes12010088. [PMID: 33445779 PMCID: PMC7828246 DOI: 10.3390/genes12010088] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/10/2021] [Accepted: 01/11/2021] [Indexed: 12/23/2022] Open
Abstract
Target of rapamycin complex 1 (TORC1), a serine/threonine-protein kinase complex highly conserved among eukaryotes, coordinates cellular growth and metabolism with environmental cues, including nutrients and growth factors. Aberrant TORC1 signaling is associated with cancers and various human diseases, and TORC1 also plays a key role in ageing and lifespan, urging current active research on the mechanisms of TORC1 regulation in a variety of model organisms. Identification and characterization of the RAG small GTPases as well as their regulators, many of which are highly conserved from yeast to humans, led to a series of breakthroughs in understanding the molecular bases of TORC1 regulation. Recruitment of mammalian TORC1 (mTORC1) by RAGs to lysosomal membranes is a key step for mTORC1 activation. Interestingly, the RAG GTPases in fission yeast are primarily responsible for attenuation of TORC1 activity on vacuoles, the yeast equivalent of lysosomes. In this review, we summarize our current knowledge about the functions of TORC1 regulators on yeast vacuoles, and illustrate the conserved and divergent mechanisms of TORC1 regulation between yeasts and mammals.
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Affiliation(s)
- Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan;
- Correspondence: ; Tel.: +81-743-72-5543
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan;
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA
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18
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Khan KA, Marineau A, Doyon P, Acevedo M, Durette É, Gingras AC, Servant MJ. TRK-Fused Gene (TFG), a protein involved in protein secretion pathways, is an essential component of the antiviral innate immune response. PLoS Pathog 2021; 17:e1009111. [PMID: 33411856 PMCID: PMC7790228 DOI: 10.1371/journal.ppat.1009111] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 10/30/2020] [Indexed: 12/15/2022] Open
Abstract
Antiviral innate immune response to RNA virus infection is supported by Pattern-Recognition Receptors (PRR) including RIG-I-Like Receptors (RLR), which lead to type I interferons (IFNs) and IFN-stimulated genes (ISG) production. Upon sensing of viral RNA, the E3 ubiquitin ligase TNF Receptor-Associated Factor-3 (TRAF3) is recruited along with its substrate TANK-Binding Kinase (TBK1), to MAVS-containing subcellular compartments, including mitochondria, peroxisomes, and the mitochondria-associated endoplasmic reticulum membrane (MAM). However, the regulation of such events remains largely unresolved. Here, we identify TRK-Fused Gene (TFG), a protein involved in the transport of newly synthesized proteins to the endomembrane system via the Coat Protein complex II (COPII) transport vesicles, as a new TRAF3-interacting protein allowing the efficient recruitment of TRAF3 to MAVS and TBK1 following Sendai virus (SeV) infection. Using siRNA and shRNA approaches, we show that TFG is required for virus-induced TBK1 activation resulting in C-terminal IRF3 phosphorylation and dimerization. We further show that the ability of the TRAF3-TFG complex to engage mTOR following SeV infection allows TBK1 to phosphorylate mTOR on serine 2159, a post-translational modification shown to promote mTORC1 signaling. We demonstrate that the activation of mTORC1 signaling during SeV infection plays a positive role in the expression of Viperin, IRF7 and IFN-induced proteins with tetratricopeptide repeats (IFITs) proteins, and that depleting TFG resulted in a compromised antiviral state. Our study, therefore, identifies TFG as an essential component of the RLR-dependent type I IFN antiviral response. Antiviral innate immune response is the first line of defence against the invading viruses through type I interferon (IFN) signaling. However, viruses have devised ways to target signaling molecules for aberrant IFN response and worsen the disease outcome. As such, deciphering the roles of new regulators of innate immunity could transform the antiviral treatment paradigm by introducing novel panviral therapeutics designed to reinforce antiviral host responses. This could be of great use in fighting recent outbreaks of severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome MERS-CoV, and the more recent SARS-CoV-2 causing the COVID-19 pandemic. However, aberrant activation of such pathways can lead to detrimental consequences, including autoimmune diseases. Regulation of type I IFN responses is thus of paramount importance. To prevent an uncontrolled response, signaling events happen in discrete subcellular compartments, therefore, distinguishing sites involved in recognition of pathogens and those permitting downstream signaling. Here, we show TFG as a new regulator of type I IFN response allowing the efficient organization of signaling molecules. TFG, thus, further substantiates the importance of the protein trafficking machinery in the regulation of optimal antiviral responses. Our findings have implications for both antiviral immunity and autoimmune diseases.
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Affiliation(s)
| | | | - Priscilla Doyon
- Faculty of Pharmacy, Université de Montréal, Montréal, Canada
| | - Mariana Acevedo
- Faculty of Pharmacy, Université de Montréal, Montréal, Canada
| | - Étienne Durette
- Faculty of Pharmacy, Université de Montréal, Montréal, Canada
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Marc J. Servant
- Faculty of Pharmacy, Université de Montréal, Montréal, Canada
- * E-mail:
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19
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David Y, Castro IG, Schuldiner M. The Fast and the Furious: Golgi Contact Sites. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2021; 4:1-15. [PMID: 35071979 PMCID: PMC7612241 DOI: 10.1177/25152564211034424] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Contact sites are areas of close apposition between two membranes that coordinate nonvesicular communication between organelles. Such interactions serve a wide range of cellular functions from regulating metabolic pathways to executing stress responses and coordinating organelle inheritance. The past decade has seen a dramatic increase in information on certain contact sites, mostly those involving the endoplasmic reticulum. However, despite its central role in the secretory pathway, the Golgi apparatus and its contact sites remain largely unexplored. In this review, we discuss the current knowledge of Golgi contact sites and share our thoughts as to why Golgi contact sites are understudied. We also highlight what exciting future directions may exist in this emerging field.
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Affiliation(s)
- Yotam David
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Inês G Castro
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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20
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Ahmed AR, Candeo A, D'Abrantes S, Needham SR, Yadav RB, Botchway SW, Parker AW. Directly imaging the localisation and photosensitization properties of the pan-mTOR inhibitor, AZD2014, in living cancer cells. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2020; 213:112055. [PMID: 33142217 PMCID: PMC7762844 DOI: 10.1016/j.jphotobiol.2020.112055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 09/24/2020] [Accepted: 10/12/2020] [Indexed: 12/17/2022]
Abstract
The range of cellular functions the mechanistic target of rapamycin (mTOR) protein performs makes it an attractive drug target for cancer therapy. However, the cellular localisation and mode of action of second generation inhibitors of mTOR is poorly understood despite the level of attention there is in targeting the mTOR protein. We have therefore studied the properties of the pan-mTOR inhibitor AZD2014, an ideal candidate to study because it is naturally fluorescent, characterising its photochemical properties in solution phase (DMSO, PBS and BSA) and within living cells, where it localises within both the nucleus and the cytoplasm but with different excited state lifetimes of 4.8 (+/- 0.5) and 3.9 (+/- 0.4) ns respectively. We measure the uptake of the inhibitor AZD2014 (7 μM) in monolayer HEK293 cells occurring with a half-life of 1 min but observe complex behaviour for 3D spheroids with the core of the spheroid showing a slower uptake and a slow biphasic behaviour at longer times. From a cellular perspective using fluorescence lifetime imaging microscopy AZD2014 was found to interact directly with GFP-tagged mTORC1 proteins including the downstream target, S6K1. We observe light sensitive behaviour of the cells containing AZD2014 which leads to cell death, in both monolayer and spheroids cells, demonstrating the potential of AZD2014 to act as a possible photodynamic drug under both single photon and multiphoton excitation and discuss its use as a photosensitizer. We also briefly characterise another pan-mTOR inhibitor, INK128.
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Affiliation(s)
- Abdullah R Ahmed
- Central Laser Facility, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, UK; Larch House, Woodlands Business Park, Breckland, Linford Wood, Milton Keynes MK14 6FG, UK
| | - Alessia Candeo
- Central Laser Facility, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, UK
| | - Sofia D'Abrantes
- Central Laser Facility, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, UK; CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Gray Laboratories, ORCRB Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Sarah R Needham
- Central Laser Facility, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, UK
| | - Rahul B Yadav
- Evotec (UK) Ltd, 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire OX14 4RZ, UK
| | - Stanley W Botchway
- Central Laser Facility, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, UK.
| | - Anthony W Parker
- Central Laser Facility, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, UK.
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21
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Takahara T, Amemiya Y, Sugiyama R, Maki M, Shibata H. Amino acid-dependent control of mTORC1 signaling: a variety of regulatory modes. J Biomed Sci 2020; 27:87. [PMID: 32799865 PMCID: PMC7429791 DOI: 10.1186/s12929-020-00679-2] [Citation(s) in RCA: 119] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 07/30/2020] [Indexed: 01/10/2023] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is an essential regulator of cell growth and metabolism through the modulation of protein and lipid synthesis, lysosome biogenesis, and autophagy. The activity of mTORC1 is dynamically regulated by several environmental cues, including amino acid availability, growth factors, energy levels, and stresses, to coordinate cellular status with environmental conditions. Dysregulation of mTORC1 activity is closely associated with various diseases, including diabetes, cancer, and neurodegenerative disorders. The discovery of Rag GTPases has greatly expanded our understanding of the regulation of mTORC1 activity by amino acids, especially leucine and arginine. In addition to Rag GTPases, other factors that also contribute to the modulation of mTORC1 activity have been identified. In this review, we discuss the mechanisms of regulation of mTORC1 activity by particular amino acids.
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Affiliation(s)
- Terunao Takahara
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan.
| | - Yuna Amemiya
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Risa Sugiyama
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Masatoshi Maki
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Hideki Shibata
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
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22
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Julian LM, Stanford WL. Organelle Cooperation in Stem Cell Fate: Lysosomes as Emerging Regulators of Cell Identity. Front Cell Dev Biol 2020; 8:591. [PMID: 32733892 PMCID: PMC7358313 DOI: 10.3389/fcell.2020.00591] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 06/17/2020] [Indexed: 12/26/2022] Open
Abstract
Regulation of stem cell fate is best understood at the level of gene and protein regulatory networks, though it is now clear that multiple cellular organelles also have critical impacts. A growing appreciation for the functional interconnectedness of organelles suggests that an orchestration of integrated biological networks functions to drive stem cell fate decisions and regulate metabolism. Metabolic signaling itself has emerged as an integral regulator of cell fate including the determination of identity, activation state, survival, and differentiation potential of many developmental, adult, disease, and cancer-associated stem cell populations and their progeny. As the primary adenosine triphosphate-generating organelles, mitochondria are well-known regulators of stem cell fate decisions, yet it is now becoming apparent that additional organelles such as the lysosome are important players in mediating these dynamic decisions. In this review, we will focus on the emerging role of organelles, in particular lysosomes, in the reprogramming of both metabolic networks and stem cell fate decisions, especially those that impact the determination of cell identity. We will discuss the inter-organelle interactions, cell signaling pathways, and transcriptional regulatory mechanisms with which lysosomes engage and how these activities impact metabolic signaling. We will further review recent data that position lysosomes as critical regulators of cell identity determination programs and discuss the known or putative biological mechanisms. Finally, we will briefly highlight the potential impact of elucidating mechanisms by which lysosomes regulate stem cell identity on our understanding of disease pathogenesis, as well as the development of refined regenerative medicine, biomarker, and therapeutic strategies.
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Affiliation(s)
- Lisa M. Julian
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - William L. Stanford
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
- Ottawa Institute of Systems Biology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
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23
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Chen C, Li J, Qin X, Wang W. Peroxisomal Membrane Contact Sites in Mammalian Cells. Front Cell Dev Biol 2020; 8:512. [PMID: 32714927 PMCID: PMC7344225 DOI: 10.3389/fcell.2020.00512] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 05/28/2020] [Indexed: 12/11/2022] Open
Abstract
Peroxisomes participate in essential cellular metabolic processes, such as oxidation of fatty acids (FAs) and maintenance of reactive oxygen species (ROS) homeostasis. Peroxisomes must communicate with surrounding organelles to exchange information and metabolites. The formation of membrane contact sites (MCSs), where protein-protein or protein-lipid complexes tether the opposing membranes of two organelles, represents an essential means of organelle crosstalk. Peroxisomal MCS (PO-MCS) studies are emerging but are still in the early stages. In this review, we summarize the identified PO-MCSs with the ER, mitochondria, lipid droplets, and lysosomes in mammalian cells and discuss their tethering mechanisms and physiological roles. We also highlight several features of PO-MCSs that may help future studies.
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Affiliation(s)
- Chao Chen
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing Li
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xuhui Qin
- Department of Human Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Wang
- Department of Human Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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24
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Abstract
A complex molecular machinery converges on the surface of lysosomes to ensure that the growth-promoting signaling mediated by mechanistic target of rapamycin complex 1 (mTORC1) is tightly controlled by the availability of nutrients and growth factors. The final step in this activation process is dependent on Rheb, a small GTPase that binds to mTOR and allosterically activates its kinase activity. Here we review the mechanisms that determine the subcellular localization of Rheb (and the closely related RhebL1 protein) as well as the significance of these mechanisms for controlling mTORC1 activation. In particular, we explore how the relatively weak membrane interactions conferred by C-terminal farnesylation are critical for the ability of Rheb to activate mTORC1. In addition to supporting transient membrane interactions, Rheb C-terminal farnesylation also supports an interaction between Rheb and the δ subunit of phosphodiesterase 6 (PDEδ). This interaction provides a potential mechanism for targeting Rheb to membranes that contain Arl2, a small GTPase that triggers the release of prenylated proteins from PDEδ. The minimal membrane targeting conferred by C-terminal farnesylation of Rheb and RhebL1 distinguishes them from other members of the Ras superfamily that possess additional membrane interaction motifs that work with farnesylation for enrichment on the specific subcellular membranes where they engage key effectors. Finally, we highlight diversity in Rheb membrane targeting mechanisms as well as the potential for alternative mTORC1 activation mechanisms across species.
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Affiliation(s)
- Brittany Angarola
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
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25
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Liu GY, Sabatini DM. mTOR at the nexus of nutrition, growth, ageing and disease. Nat Rev Mol Cell Biol 2020; 21:183-203. [PMID: 31937935 PMCID: PMC7102936 DOI: 10.1038/s41580-019-0199-y] [Citation(s) in RCA: 1322] [Impact Index Per Article: 330.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2019] [Indexed: 12/21/2022]
Abstract
The mTOR pathway integrates a diverse set of environmental cues, such as growth factor signals and nutritional status, to direct eukaryotic cell growth. Over the past two and a half decades, mapping of the mTOR signalling landscape has revealed that mTOR controls biomass accumulation and metabolism by modulating key cellular processes, including protein synthesis and autophagy. Given the pathway's central role in maintaining cellular and physiological homeostasis, dysregulation of mTOR signalling has been implicated in metabolic disorders, neurodegeneration, cancer and ageing. In this Review, we highlight recent advances in our understanding of the complex regulation of the mTOR pathway and discuss its function in the context of physiology, human disease and pharmacological intervention.
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Affiliation(s)
- Grace Y Liu
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
- Broad Institute, Cambridge, MA, USA
- The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Broad Institute, Cambridge, MA, USA.
- The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA, USA.
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26
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Huang X, Jiang C, Yu L, Yang A. Current and Emerging Approaches for Studying Inter-Organelle Membrane Contact Sites. Front Cell Dev Biol 2020; 8:195. [PMID: 32292782 PMCID: PMC7118198 DOI: 10.3389/fcell.2020.00195] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 03/09/2020] [Indexed: 12/24/2022] Open
Abstract
Inter-organelle membrane contact sites (MCSs) are classically defined as areas of close proximity between heterologous membranes and established by specific proteins (termed tethers). The interest on MCSs has rapidly increased in the last years, since MCSs play a crucial role in the transfer of cellular components between different organelles and have been involved in important cellular functions such as apoptosis, organelle division and biogenesis, and cell growth. Recently, an unprecedented depth and breadth in insights into the details of MCSs have been uncovered. On one hand, extensive MCSs (organelles interactome) are revealed by comprehensive analysis of organelle network with high temporal-spatial resolution at the system level. On the other hand, more and more tethers involving in MCSs are identified and further works are focusing on addressing the role of these tethers in regulating the function of MCSs at the molecular level. These enormous progresses largely depend on the powerful approaches, including several different types of microscopies and various biochemical techniques. These approaches have greatly accelerated recent advances in MCSs at the system and molecular level. In this review, we summarize the current and emerging approaches for studying MCSs, such as various microscopies, proximity-driven fluorescent signal generation and proximity-dependent biotinylation. In addition, we highlight the advantages and disadvantages of the techniques to provide a general guidance for the study of MCSs.
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Affiliation(s)
- Xue Huang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Chen Jiang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Lihua Yu
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Aimin Yang
- School of Life Sciences, Chongqing University, Chongqing, China
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27
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Ikari S, Lu SL, Hao F, Imai K, Araki Y, Yamamoto YH, Tsai CY, Nishiyama Y, Shitan N, Yoshimori T, Otomo T, Noda T. Starvation-induced autophagy via calcium-dependent TFEB dephosphorylation is suppressed by Shigyakusan. PLoS One 2020; 15:e0230156. [PMID: 32134989 PMCID: PMC7058311 DOI: 10.1371/journal.pone.0230156] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 02/22/2020] [Indexed: 12/11/2022] Open
Abstract
Kampo, a system of traditional Japanese therapy utilizing mixtures of herbal medicine, is widely accepted in the Japanese medical system. Kampo originated from traditional Chinese medicine, and was gradually adopted into a Japanese style. Although its effects on a variety of diseases are appreciated, the underlying mechanisms remain mostly unclear. Using a quantitative tf-LC3 system, we conducted a high-throughput screen of 128 kinds of Kampo to evaluate the effects on autophagy. The results revealed a suppressive effect of Shigyakusan/TJ-35 on autophagic activity. TJ-35 specifically suppressed dephosphorylation of ULK1 and TFEB, among several TORC1 substrates, in response to nutrient deprivation. TFEB was dephosphorylated by calcineurin in a Ca2+ dependent manner. Cytosolic Ca2+ concentration was increased in response to nutrient starvation, and TJ-35 suppressed this increase. Thus, TJ-35 prevents the starvation-induced Ca2+ increase, thereby suppressing induction of autophagy.
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Affiliation(s)
- Sumiko Ikari
- Center for Frontier Oral Science, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Shiou-Ling Lu
- Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Suita, Osaka, Japan
| | - Feike Hao
- Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Suita, Osaka, Japan
- China National Research Institute of Food and Fermentation Industries, Beijing, China
| | - Kenta Imai
- Department of Intracellular Membrane Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Yasuhiro Araki
- Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Suita, Osaka, Japan
| | - Yo-hei Yamamoto
- Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Suita, Osaka, Japan
| | - Chao-Yuan Tsai
- Laboratory of Immune Regulation, Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
| | - Yumi Nishiyama
- Medicinal Botanical Garden, Kobe Pharmaceutical University, Kobe, Hyogo, Japan
| | - Nobukazu Shitan
- Laboratory of Medicinal Cell Biology, Kobe Pharmaceutical University, Kobe, Hyogo, Japan
| | - Tamotsu Yoshimori
- Department of Intracellular Membrane Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Takanobu Otomo
- Department of Molecular and Genetic Medicine, Kawasaki Medical School, Kurashiki, Okayama, Japan
| | - Takeshi Noda
- Center for Frontier Oral Science, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
- Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Suita, Osaka, Japan
- * E-mail:
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28
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Rahmani S, Defferrari MS, Wakarchuk WW, Antonescu CN. Energetic adaptations: Metabolic control of endocytic membrane traffic. Traffic 2019; 20:912-931. [DOI: 10.1111/tra.12705] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 09/11/2019] [Accepted: 10/13/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Sadia Rahmani
- Department of Chemistry and BiologyRyerson University Toronto Ontario Canada
| | | | - Warren W. Wakarchuk
- Department of Chemistry and BiologyRyerson University Toronto Ontario Canada
- Department of Biological SciencesUniversity of Alberta Edmonton Alberta Canada
| | - Costin N. Antonescu
- Department of Chemistry and BiologyRyerson University Toronto Ontario Canada
- Keenan Research Centre for Biomedical Science of St. Michael's Hospital Toronto Ontario Canada
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29
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Angarola B, Ferguson SM. Weak membrane interactions allow Rheb to activate mTORC1 signaling without major lysosome enrichment. Mol Biol Cell 2019; 30:2750-2760. [PMID: 31532697 PMCID: PMC6789162 DOI: 10.1091/mbc.e19-03-0146] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Stable localization of the Rheb GTPase to lysosomes is thought to be required for activation of mTOR complex 1 (mTORC1) signaling. However, the lysosome targeting mechanisms for Rheb remain unclear. We therefore investigated the relationship between Rheb subcellular localization and mTORC1 activation. Surprisingly, we found that Rheb was undetectable at lysosomes. Nonetheless, functional assays in knockout human cells revealed that farnesylation of the C-terminal CaaX motif on Rheb was essential for Rheb-dependent mTORC1 activation. Although farnesylated Rheb exhibited partial endoplasmic reticulum (ER) localization, constitutively targeting Rheb to ER membranes did not support mTORC1 activation. Further systematic analysis of Rheb lipidation revealed that weak, nonselective, membrane interactions support Rheb-dependent mTORC1 activation without the need for a specific lysosome targeting motif. Collectively, these results argue against stable interactions of Rheb with lysosomes and instead that transient membrane interactions optimally allow Rheb to activate mTORC1 signaling.
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Affiliation(s)
- Brittany Angarola
- Departments of Cell Biology and Neuroscience, Yale University School of Medicine, New Haven, CT 06510
| | - Shawn M Ferguson
- Departments of Cell Biology and Neuroscience, Yale University School of Medicine, New Haven, CT 06510
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30
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Zhou C, Wang M, Yang J, Xiong H, Wang Y, Tang J. Integral membrane protein 2A inhibits cell growth in human breast cancer via enhancing autophagy induction. Cell Commun Signal 2019; 17:105. [PMID: 31438969 PMCID: PMC6704577 DOI: 10.1186/s12964-019-0422-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 08/16/2019] [Indexed: 02/06/2023] Open
Abstract
Background Breast cancer is a life-threatening disease in females and the leading cause of mortality among the female population, presenting huge challenges for prognosis and treatment. ITM2A is a member of the BRICHOS superfamily, which are thought to have a chaperone function. ITM2A has been identified to related to ovarian cancer progress recently. However, the biological role of ITM2A in breast cancer remains largely unclear. Methods Quantitative real-time polymerase chain reaction (qRT-PCR), western blotting assay and immunohistochemistry staining were used to analyzed the expression level of ITM2A. The patient overall survival versus ITM2A expression level was evaluated by Kaplan-Meier analysis. MTT assay, EdU incorporation assay and colony formation assay were used to evaluated the role of ITM2A on breast cancer cell proliferation. Autophagy was explored through autophagic flux detection using a confocal microscope and autophagic vacuoles investigation under a transmission electron microscopy (TEM). In vitro kinase assay was used to investigated the phosphorylation modification of ITM2A by HUNK. Results Our data showed that the expression of integral membrane protein 2A (ITM2A) was significantly down-regulated in human breast cancer tissues and cell lines. Kaplan-Meier analysis indicated that patients presenting with reduced ITM2A expression exhibited poor overall survival, and expression significantly correlated with age, progesterone receptor status, TNM classification and tumor stage. ITM2A overexpression significantly inhibited the proliferation of breast cancer cells. By studying several autophagic markers and events in human breast cancer SKBR-3 cells, we further demonstrated that ITM2A is a novel positive regulator of autophagy through an mTOR-dependent manner. Moreover, we found that ITM2A was phosphorylated at T35 by HUNK, a serine/threonine kinase significantly correlated with human breast cancer overall survival and HER2-induced mammary tumorigenesis. Conclusion Our study provided evidence that ITM2A functions as a novel prognostic marker and represents a potential therapeutic target. Electronic supplementary material The online version of this article (10.1186/s12964-019-0422-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Cefan Zhou
- The State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Hubei University of Technology, Wuhan, China
| | - Ming Wang
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan, China
| | - Jing Yang
- Robert H. Lurie Comprehensive Cancer Center, Department of Medicine-Division of Hematology/Oncology, Northwestern University Feinberg School of Medicine, Chicago, USA
| | - Hui Xiong
- Department of Clinical Laboratory, Hospital of Southern University of Science & Technology, Shenzhen, Guangzhou, China.,XiLi People's Hospital, Shenzhen, Guangzhou, China
| | - Yefu Wang
- The State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.
| | - Jingfeng Tang
- The State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China. .,National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Hubei University of Technology, Wuhan, China.
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31
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Walton ZE, Brooks RC, Dang CV. mTOR Senses Intracellular pH through Lysosome Dispersion from RHEB. Bioessays 2019; 41:e1800265. [PMID: 31157925 PMCID: PMC6730656 DOI: 10.1002/bies.201800265] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 04/18/2019] [Indexed: 02/04/2023]
Abstract
Acidity, generated in hypoxia or hypermetabolic states, perturbs homeostasis and is a feature of solid tumors. That acid peripherally disperses lysosomes is a three-decade-old observation, yet one little understood or appreciated. However, recent work has recognized the inhibitory impact this spatial redistribution has on mechanistic target of rapamycin complex 1 (mTORC1), a key regulator of metabolism. This finding argues for a paradigm shift in localization of mTORC1 activator Ras homolog enriched in brain (RHEB), a conclusion several others have now independently reached. Thus, mTORC1, known to sense amino acids, mitogens, and energy to restrict biosynthesis to times of adequate resources, also senses pH and, via dampened mTOR-governed synthesis of clock proteins, regulates the circadian clock to achieve concerted responses to metabolic stress. While this may allow cancer to endure metabolic deprivation, immune cell mTOR signaling likewise exhibits pH sensitivity, suggesting that suppression of antitumor immune function by solid tumor acidity may additionally fuel cancers, an obstacle potentially reversible through therapeutic pH manipulation.
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Affiliation(s)
| | | | - Chi V. Dang
- Ludwig Institute for Cancer Research, New York, NY 10017
- The Wistar Institute, Philadelphia, PA 19104
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32
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Inpanathan S, Botelho RJ. The Lysosome Signaling Platform: Adapting With the Times. Front Cell Dev Biol 2019; 7:113. [PMID: 31281815 PMCID: PMC6595708 DOI: 10.3389/fcell.2019.00113] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/05/2019] [Indexed: 12/12/2022] Open
Abstract
Lysosomes are the terminal degradative compartment of autophagy, endocytosis and phagocytosis. What once was viewed as a simple acidic organelle in charge of macromolecular digestion has emerged as a dynamic organelle capable of integrating cellular signals and producing signal outputs. In this review, we focus on the concept that the lysosome surface serves as a platform to assemble major signaling hubs like mTORC1, AMPK, GSK3 and the inflammasome. These molecular assemblies integrate and facilitate cross-talk between signals such as amino acid and energy levels, membrane damage and infection, and ultimately enable responses such as autophagy, cell growth, membrane repair and microbe clearance. In particular, we review how molecular machinery like the vacuolar-ATPase proton pump, sestrins, the GATOR complexes, and the Ragulator, modulate mTORC1, AMPK, GSK3 and inflammation. We then elaborate how these signals control autophagy initiation and resolution, TFEB-mediated lysosome adaptation, lysosome remodeling, antigen presentation, inflammation, membrane damage repair and clearance. Overall, by being at the cross-roads for several membrane pathways, lysosomes have emerged as the ideal surveillance compartment to sense, integrate and elicit cellular behavior and adaptation in response to changing environmental and cellular conditions.
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Affiliation(s)
- Subothan Inpanathan
- Department of Chemistry and Biology, Graduate Program in Molecular Science, Ryerson University, Toronto, ON, Canada
| | - Roberto J Botelho
- Department of Chemistry and Biology, Graduate Program in Molecular Science, Ryerson University, Toronto, ON, Canada
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33
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Arhzaouy K, Papadopoulos C, Schulze N, Pittman SK, Meyer H, Weihl CC. VCP maintains lysosomal homeostasis and TFEB activity in differentiated skeletal muscle. Autophagy 2019; 15:1082-1099. [PMID: 30654731 DOI: 10.1080/15548627.2019.1569933] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Differentiated tissue is particularly vulnerable to alterations in protein and organelle homeostasis. The essential protein VCP, mutated in hereditary inclusion body myopathy, amyotrophic lateral sclerosis and frontotemporal dementia, is critical for efficient clearance of misfolded proteins and damaged organelles in dividing cells, but its role in terminally differentiated tissue affected by disease mutations is less clear. To understand the relevance of VCP in differentiated tissue, we inactivated it in skeletal muscle of adult mice. Surprisingly, knockout muscle demonstrated a necrotic myopathy with increased macroautophagic/autophagic proteins and damaged lysosomes. This was not solely due to a defect in autophagic degradation because age-matched mice with muscle inactivation of the autophagy essential protein, ATG5, did not demonstrate a myopathy. Notably, myofiber necrosis was preceded by upregulation of LGALS3/Galectin-3, a marker of damaged lysosomes, and TFEB activation, suggesting early defects in the lysosomal system. Consistent with that, myofiber necrosis was recapitulated by chemical induction of lysosomal membrane permeabilization (LMP) in skeletal muscle. Moreover, TFEB was activated after LMP in cells, but activation and nuclear localization of TFEB persisted upon VCP inactivation or disease mutant expression. Our data identifies VCP as central mediator of both lysosomal clearance and biogenesis in skeletal muscle. Abbreviations: AAA: ATPases Associated with diverse cellular Activities; TUBA1A/α-tubulin: tubulin alpha 1a; ATG5: autophagy related 5; ATG7: autophagy related 7; ACTA1: actin alpha 1, skeletal muscle; CLEAR: coordinated lysosomal expression and regulation; CTSB/D: cathepsin B/D; Ctrl: control; DAPI: diamidino-2-phenylindole; EBSS: Earle's balanced salt solution; ELDR: endolysosomal damage response; ESCRT: endosomal sorting complexes required for transport; Gastroc/G: gastrocnemius; H&E: hematoxylin and eosin; HSPA5/GRP78: heat shock protein family A (Hsp70) member 5; IBMPFD/ALS: inclusion body myopathy associated with Paget disease of the bone, frontotemporal dementia and amyotrophic lateral sclerosis; i.p.: intraperitoneal; LAMP1/2: lysosomal-associated membrane protein 1/2; LLOMe: Leu-Leu methyl ester hydrobromide; LGALS3/Gal3: galectin 3; LMP: lysosomal membrane permeabilization; MTOR: mechanistic target of rapamycin kinase; MYL1: myosin light chain 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MSP: multisystem proteinopathy; PBS: phosphate-buffered saline; PCR: polymerase chain reaction; Quad/Q: quadriceps; RHEB: Ras homolog, mTORC1 binding; SQSTM1: sequestosome 1; TFEB: transcription factor EB; TA: tibialis anterior; siRNA: small interfering RNA; SQSTM1/p62, sequestosome 1; TARDBP/TDP-43: TAR DNA binding protein; TBS: Tris-buffered saline; TXFN, tamoxifen; UBXN6/UBXD1: UBX domain protein 6; VCP: valosin containing protein; WT: wild-type.
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Affiliation(s)
- Khalid Arhzaouy
- a Department of Neurology, Hope Center for Neurological Diseases , Washington University School of Medicine , St Louis , MO , USA
| | - Chrisovalantis Papadopoulos
- b Molecular Biology I, Faculty of Biology, Centre for Medical Biotechnology , University of Duisburg-Essen , Essen , Germany
| | - Nina Schulze
- c Imaging Centre Campus Essen (ICCE), Centre for Medical Biotechnology (ZMB) , University of Duisburg-Essen , Essen , Germany
| | - Sara K Pittman
- a Department of Neurology, Hope Center for Neurological Diseases , Washington University School of Medicine , St Louis , MO , USA
| | - Hemmo Meyer
- b Molecular Biology I, Faculty of Biology, Centre for Medical Biotechnology , University of Duisburg-Essen , Essen , Germany
| | - Conrad C Weihl
- a Department of Neurology, Hope Center for Neurological Diseases , Washington University School of Medicine , St Louis , MO , USA
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Chao LH, Avruch J. Cryo-EM insight into the structure of MTOR complex 1 and its interactions with Rheb and substrates. F1000Res 2019; 8. [PMID: 30647914 PMCID: PMC6325617 DOI: 10.12688/f1000research.16109.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/18/2018] [Indexed: 12/31/2022] Open
Abstract
The mechanistic target of rapamycin (MTOR) is a giant protein kinase that, together with the accessory proteins Raptor and mLst8, forms a complex of over 1 MDa known as MTOR complex 1 (MTORC1). MTORC1, through its protein kinase activity, controls the accretion of cell mass through the regulation of gene transcription, mRNA translation, and protein turnover. MTORC1 is activated in an interdependent manner by insulin/growth factors and nutrients, especially amino acids, and is inhibited by stressors such as hypoxia and by the drug rapamycin. The action of insulin/growth factors converges on the small GTPase Rheb, which binds directly to the MTOR polypeptide in MTORC1 and, in its GTP-bound state, initiates kinase activation. Biochemical studies established that MTORC1 exists as a dimer of the MTOR/Raptor/mLst8 trimer, and progressive refinements in cryo-electron microscopy (cryo-EM) have enabled an increasingly clear picture of the architecture of MTORC1, culminating in a deep understanding of how MTORC1 interacts with and phosphorylates its best-known substrates-the eIF-4E binding protein/4E-BP, the p70 S6 kinase/S6K1B, and PRAS40/AKT1S1-and how this is inhibited by rapamycin. Most recently, Rheb-GTP has been shown to bind to MTORC1 in a cooperative manner at an allosteric site remote from the kinase domain that twists the latter into a catalytically competent configuration. Herein, we review the recent cryo-EM and associated biochemical studies of MTORC1 and seek to integrate these new results with the known physiology of MTORC1 regulation and signaling.
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Affiliation(s)
- Luke H Chao
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Joseph Avruch
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Medicine, Harvard Medical School, Boston, MA, USA
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35
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The Golgi architecture and cell sensing. Biochem Soc Trans 2018; 46:1063-1072. [DOI: 10.1042/bst20180323] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 08/06/2018] [Accepted: 08/21/2018] [Indexed: 12/23/2022]
Abstract
An array of signalling molecules are located at the Golgi apparatus, including phosphoinositides, small GTPases, kinases, and phosphatases, which are linked to multiple signalling pathways. Initially considered to be associated predominantly with membrane trafficking, signalling pathways at the Golgi are now recognised to regulate a diverse range of higher-order functions. Many of these signalling pathways are influenced by the architecture of the Golgi. In vertebrate cells, the Golgi consists of individual stacks fused together into a compact ribbon structure and the function of this ribbon structure has been enigmatic. Notably, recent advances have identified a role for the Golgi ribbon in regulation of cellular processes. Fragmentation of the Golgi ribbon results in modulation of many signalling pathways. Various diseases and disorders, including cancer and neurodegeneration, are associated with the loss of the Golgi ribbon and the appearance of a dispersed fragmented Golgi. Here, we review the emerging theme of the Golgi as a cell sensor and highlight the relationship between the morphological status of the Golgi in vertebrate cells and the modulation of signalling networks.
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