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Robles-Flores M, Moreno-Londoño AP, Castañeda-Patlán MC. Signaling Pathways Involved in Nutrient Sensing Control in Cancer Stem Cells: An Overview. Front Endocrinol (Lausanne) 2021; 12:627745. [PMID: 33828530 PMCID: PMC8020906 DOI: 10.3389/fendo.2021.627745] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 02/18/2021] [Indexed: 12/14/2022] Open
Abstract
Cancer cells characteristically have a high proliferation rate. Because tumor growth depends on energy-consuming anabolic processes, including biosynthesis of protein, lipid, and nucleotides, many tumor-associated conditions, including intermittent oxygen deficiency due to insufficient vascularization, oxidative stress, and nutrient deprivation, results from fast growth. To cope with these environmental stressors, cancer cells, including cancer stem cells, must adapt their metabolism to maintain cellular homeostasis. It is well- known that cancer stem cells (CSC) reprogram their metabolism to adapt to live in hypoxic niches. They usually change from oxidative phosphorylation to increased aerobic glycolysis even in the presence of oxygen. However, as opposed to most differentiated cancer cells relying on glycolysis, CSCs can be highly glycolytic or oxidative phosphorylation-dependent, displaying high metabolic plasticity. Although the influence of the metabolic and nutrient-sensing pathways on the maintenance of stemness has been recognized, the molecular mechanisms that link these pathways to stemness are not well known. Here in this review, we describe the most relevant signaling pathways involved in nutrient sensing and cancer cell survival. Among them, Adenosine monophosphate (AMP)-activated protein kinase (AMPK) pathway, mTOR pathway, and Hexosamine Biosynthetic Pathway (HBP) are critical sensors of cellular energy and nutrient status in cancer cells and interact in complex and dynamic ways.
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Affiliation(s)
- Martha Robles-Flores
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico
| | - Angela P Moreno-Londoño
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico
| | - M Cristina Castañeda-Patlán
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico
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202
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Suginohara T, Wakabayashi K, Ato S, Ogasawara R. Effect of 2-deoxyglucose-mediated inhibition of glycolysis on the regulation of mTOR signaling and protein synthesis before and after high-intensity muscle contraction. Metabolism 2021; 114:154419. [PMID: 33161019 DOI: 10.1016/j.metabol.2020.154419] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Glycolysis controls mTORC1 signaling and protein synthesis. In skeletal muscle, glucose metabolism increases with both exercise/contraction intensity and volume, and therefore, high-intensity muscle contraction (HiMC) such as resistance exercise facilitates glycolysis including glucose uptake and glycogen breakdown. However, it is unknown whether glycolysis regulates HiMC-induced mTORC1 activation and increase in protein synthesis. METHODS To determine whether glycolysis regulates basal and HiMC-induced mTORC1 signaling and protein synthesis, we employed 2-deoxyglucose (2-DG) to inhibit glycolysis and isometrically contracted the gastrocnemius muscle of Sprague Dawley rats using percutaneous electrical stimulation. RESULTS Inhibition of glycolysis by 2-DG inhibited basal phosphorylation of p70S6K and 4E-BP1 (downstream targets of mTORC1) and protein synthesis (all P < 0.05) independent of AMPK phosphorylation. AMPK phosphorylation was comparably increased after HiMC at 0 h post HiMC and returned to basal levels 6 h post HiMC in both vehicle- and 2-DG-treated groups. Glycolysis inhibition attenuated muscle contraction-induced phosphorylation of 4E-BP1 at 6 h post HiMC (P < 0.05) but not p70S6K phosphorylation and protein synthesis. CONCLUSION Although glycolysis is involved in basal but not HiMC-induced muscle protein synthesis, it regulates both basal and HiMC-induced mTORC1 signaling, and may play key roles in skeletal muscle adaptation to HiMC.
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Affiliation(s)
- Takeshi Suginohara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Koki Wakabayashi
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Satoru Ato
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan.
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203
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Chen X, Xu X, Chen Y, Cheung JC, Wang H, Jiang J, de Val N, Fox T, Gellert M, Yang W. Structure of an activated DNA-PK and its implications for NHEJ. Mol Cell 2020; 81:801-810.e3. [PMID: 33385326 DOI: 10.1016/j.molcel.2020.12.015] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/17/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023]
Abstract
DNA-dependent protein kinase (DNA-PK), like all phosphatidylinositol 3-kinase-related kinases (PIKKs), is composed of conserved FAT and kinase domains (FATKINs) along with solenoid structures made of HEAT repeats. These kinases are activated in response to cellular stress signals, but the mechanisms governing activation and regulation remain unresolved. For DNA-PK, all existing structures represent inactive states with resolution limited to 4.3 Å at best. Here, we report the cryoelectron microscopy (cryo-EM) structures of DNA-PKcs (DNA-PK catalytic subunit) bound to a DNA end or complexed with Ku70/80 and DNA in both inactive and activated forms at resolutions of 3.7 Å overall and 3.2 Å for FATKINs. These structures reveal the sequential transition of DNA-PK from inactive to activated forms. Most notably, activation of the kinase involves previously unknown stretching and twisting within individual solenoid segments and loosens DNA-end binding. This unprecedented structural plasticity of helical repeats may be a general regulatory mechanism of HEAT-repeat proteins.
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Affiliation(s)
- Xuemin Chen
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiang Xu
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yun Chen
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joyce C Cheung
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Huaibin Wang
- Laboratory of Cell and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jiansen Jiang
- Laboratory of Membrane Proteins and Structural Biology, NHLBI, National Institutes of Health, Bethesda, MD 20892, USA
| | - Natalia de Val
- Cancer Research Technology Program Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21701, USA
| | - Tara Fox
- Cancer Research Technology Program Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21701, USA
| | - Martin Gellert
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Wei Yang
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
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204
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Ramlaul K, Fu W, Li H, de Martin Garrido N, He L, Trivedi M, Cui W, Aylett CHS, Wu G. Architecture of the Tuberous Sclerosis Protein Complex. J Mol Biol 2020; 433:166743. [PMID: 33307091 PMCID: PMC7840889 DOI: 10.1016/j.jmb.2020.166743] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 11/26/2020] [Accepted: 12/02/2020] [Indexed: 12/11/2022]
Abstract
We report the molecular architecture of the TSC protein complex by single-particle cryo-EM. The TSCC forms an elongated scorpion-like structure, with pincer, body and a barbed tail. The body is TSC2, while TSC1 runs along its surface and makes up the pincer, and TBC1D7 the barb. The TSC2 GAP domain is poised to bind a pair of Rheb molecules at a similar separation to the pair in activated mTORC1.
The Tuberous Sclerosis Complex (TSC) protein complex (TSCC), comprising TSC1, TSC2, and TBC1D7, is widely recognised as a key integration hub for cell growth and intracellular stress signals upstream of the mammalian target of rapamycin complex 1 (mTORC1). The TSCC negatively regulates mTORC1 by acting as a GTPase-activating protein (GAP) towards the small GTPase Rheb. Both human TSC1 and TSC2 are important tumour suppressors, and mutations in them underlie the disease tuberous sclerosis. We used single-particle cryo-EM to reveal the organisation and architecture of the complete human TSCC. We show that TSCC forms an elongated scorpion-like structure, consisting of a central “body”, with a “pincer” and a “tail” at the respective ends. The “body” is composed of a flexible TSC2 HEAT repeat dimer, along the surface of which runs the TSC1 coiled-coil backbone, breaking the symmetry of the dimer. Each end of the body is structurally distinct, representing the N- and C-termini of TSC1; a “pincer” is formed by the highly flexible N-terminal TSC1 core domains and a barbed “tail” makes up the TSC1 coiled-coil-TBC1D7 junction. The TSC2 GAP domain is found abutting the centre of the body on each side of the dimerisation interface, poised to bind a pair of Rheb molecules at a similar separation to the pair in activated mTORC1. Our architectural dissection reveals the mode of association and topology of the complex, casts light on the recruitment of Rheb to the TSCC, and also hints at functional higher order oligomerisation, which has previously been predicted to be important for Rheb-signalling suppression.
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Affiliation(s)
- Kailash Ramlaul
- Section for Structural Biology, Department of Infectious Disease, Imperial College London, Exhibition Road, London SW7 2BB, United Kingdom
| | - Wencheng Fu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, The Joint International Research Laboratory of Metabolic & Developmental Sciences MOE, Shanghai Jiao Tong University, Shanghai, China
| | - Hua Li
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, The Joint International Research Laboratory of Metabolic & Developmental Sciences MOE, Shanghai Jiao Tong University, Shanghai, China
| | - Natàlia de Martin Garrido
- Section for Structural Biology, Department of Infectious Disease, Imperial College London, Exhibition Road, London SW7 2BB, United Kingdom
| | - Lin He
- Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai, China
| | - Manjari Trivedi
- Institute of Reproductive and Developmental Biology, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom
| | - Wei Cui
- Institute of Reproductive and Developmental Biology, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom
| | - Christopher H S Aylett
- Section for Structural Biology, Department of Infectious Disease, Imperial College London, Exhibition Road, London SW7 2BB, United Kingdom.
| | - Geng Wu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, The Joint International Research Laboratory of Metabolic & Developmental Sciences MOE, Shanghai Jiao Tong University, Shanghai, China.
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205
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Deaver JW, López SM, Ryan PJ, Nghiem PP, Riechman SE, Fluckey JD. Regulation of cellular anabolism by mTOR: or how I learned to stop worrying and love translation. SPORTS MEDICINE AND HEALTH SCIENCE 2020; 2:195-201. [PMID: 35782997 PMCID: PMC9219308 DOI: 10.1016/j.smhs.2020.11.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 12/15/2022] Open
Affiliation(s)
- J. William Deaver
- Department of Health and Kinesiology, 107 Gilchrist Building, 2929 Research Parkway, Texas A&M University, College Station, TX, USA
| | - Sara Mata López
- Department of Veterinary Integrative Biosciences, 402 Raymond Stotzer Pkwy Building 2, Texas A&M University, College Station, TX, USA
| | - Patrick J. Ryan
- Department of Health and Kinesiology, 107 Gilchrist Building, 2929 Research Parkway, Texas A&M University, College Station, TX, USA
| | - Peter P. Nghiem
- Department of Veterinary Integrative Biosciences, 402 Raymond Stotzer Pkwy Building 2, Texas A&M University, College Station, TX, USA
| | - Steven E. Riechman
- Department of Health and Kinesiology, 107 Gilchrist Building, 2929 Research Parkway, Texas A&M University, College Station, TX, USA
| | - James D. Fluckey
- Department of Health and Kinesiology, 107 Gilchrist Building, 2929 Research Parkway, Texas A&M University, College Station, TX, USA
- Corresponding author. Department of Health and Kinesiology, 107 Gilchrist Building, Room 313, 2929 Research Parkway, Texas A&M University, College Station, TX, 77843-4243, USA.
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206
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Ichimiya T, Yamakawa T, Hirano T, Yokoyama Y, Hayashi Y, Hirayama D, Wagatsuma K, Itoi T, Nakase H. Autophagy and Autophagy-Related Diseases: A Review. Int J Mol Sci 2020; 21:ijms21238974. [PMID: 33255983 PMCID: PMC7729615 DOI: 10.3390/ijms21238974] [Citation(s) in RCA: 151] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/19/2020] [Accepted: 11/24/2020] [Indexed: 12/20/2022] Open
Abstract
Autophagy refers to the process involving the decomposition of intracellular components via lysosomes. Autophagy plays an important role in maintaining and regulating cell homeostasis by degrading intracellular components and providing degradation products to cells. In vivo, autophagy has been shown to be involved in the starvation response, intracellular quality control, early development, and cell differentiation. Recent studies have revealed that autophagy dysfunction is implicated in neurodegenerative diseases and tumorigenesis. In addition to the discovery of certain disease-causing autophagy-related mutations and elucidation of the pathogenesis of conditions resulting from the abnormal degradation of selective autophagy substrates, the activation of autophagy is essential for prolonging life and suppressing aging. This article provides a comprehensive review of the role of autophagy in health, physiological function, and autophagy-related disease.
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Affiliation(s)
- Tadashi Ichimiya
- Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan; (T.I.); (T.Y.); (T.H.); (Y.Y.); (Y.H.); (D.H.); (K.W.)
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo 160-0023, Japan;
| | - Tsukasa Yamakawa
- Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan; (T.I.); (T.Y.); (T.H.); (Y.Y.); (Y.H.); (D.H.); (K.W.)
| | - Takehiro Hirano
- Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan; (T.I.); (T.Y.); (T.H.); (Y.Y.); (Y.H.); (D.H.); (K.W.)
| | - Yoshihiro Yokoyama
- Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan; (T.I.); (T.Y.); (T.H.); (Y.Y.); (Y.H.); (D.H.); (K.W.)
| | - Yuki Hayashi
- Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan; (T.I.); (T.Y.); (T.H.); (Y.Y.); (Y.H.); (D.H.); (K.W.)
| | - Daisuke Hirayama
- Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan; (T.I.); (T.Y.); (T.H.); (Y.Y.); (Y.H.); (D.H.); (K.W.)
| | - Kohei Wagatsuma
- Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan; (T.I.); (T.Y.); (T.H.); (Y.Y.); (Y.H.); (D.H.); (K.W.)
| | - Takao Itoi
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo 160-0023, Japan;
| | - Hiroshi Nakase
- Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan; (T.I.); (T.Y.); (T.H.); (Y.Y.); (Y.H.); (D.H.); (K.W.)
- Correspondence: ; Tel.: +81-11-611-2111
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207
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Tang T, Yang ZY, Wang D, Yang XY, Wang J, Li L, Wen Q, Gao L, Bian XW, Yu SC. The role of lysosomes in cancer development and progression. Cell Biosci 2020; 10:131. [PMID: 33292489 PMCID: PMC7677787 DOI: 10.1186/s13578-020-00489-x] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 10/29/2020] [Indexed: 01/01/2023] Open
Abstract
Lysosomes are an important component of the inner membrane system and participate in numerous cell biological processes, such as macromolecular degradation, antigen presentation, intracellular pathogen destruction, plasma membrane repair, exosome release, cell adhesion/migration and apoptosis. Thus, lysosomes play important roles in cellular activity. In addition, previous studies have shown that lysosomes may play important roles in cancer development and progression through the abovementioned biological processes and that the functional status and spatial distribution of lysosomes are closely related to cancer cell proliferation, energy metabolism, invasion and metastasis, immune escape and tumor-associated angiogenesis. Therefore, identifying the factors and mechanisms that regulate the functional status and spatial distribution of lysosomes and elucidating the relationship between lysosomes and the development and progression of cancer can provide important information for cancer diagnosis and prognosis prediction and may yield new therapeutic targets. This study briefly reviews the above information and explores the potential value of lysosomes in cancer therapy.
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Affiliation(s)
- Tao Tang
- Department of Stem Cell and Regenerative Medicine, Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Ze-Yu Yang
- Department of Stem Cell and Regenerative Medicine, Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Di Wang
- Department of Stem Cell and Regenerative Medicine, Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Xian-Yan Yang
- Department of Stem Cell and Regenerative Medicine, Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Jun Wang
- Department of Stem Cell and Regenerative Medicine, Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Lin Li
- Department of Stem Cell and Regenerative Medicine, Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Qian Wen
- Department of Stem Cell and Regenerative Medicine, Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Lei Gao
- Department of Hematology, Xinqiao Hospital, Third Military Medical University (Army Medical University), Chongqing, 400037, China
| | - Xiu-Wu Bian
- Department of Stem Cell and Regenerative Medicine, Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Shi-Cang Yu
- Department of Stem Cell and Regenerative Medicine, Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China.
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208
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Unraveling the multifaceted nature of the nuclear function of mTOR. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118907. [PMID: 33189783 DOI: 10.1016/j.bbamcr.2020.118907] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/02/2020] [Accepted: 11/08/2020] [Indexed: 01/25/2023]
Abstract
Positioned at the axis between the cell and its environment, mTOR directs a wide range of cellular activity in response to nutrients, growth factors, and stress. Our understanding of the role of mTOR is evolving beyond the spatial confines of the cytosol, and its role in the nucleus becoming ever more apparent. In this review, we will address various studies that explore the role of nuclear mTOR (nmTOR) in specific cellular programs and how these pathways influence one another. To understand the emerging roles of nuclear mTOR, we discuss data and propose plausible mechanisms to offer novel ideas, hypotheses, and future research directions.
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209
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Tannous EA, Yates LA, Zhang X, Burgers PM. Mechanism of auto-inhibition and activation of Mec1 ATR checkpoint kinase. Nat Struct Mol Biol 2020; 28:50-61. [PMID: 33169019 PMCID: PMC7855233 DOI: 10.1038/s41594-020-00522-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 09/24/2020] [Indexed: 01/01/2023]
Abstract
In response to DNA damage or replication fork stalling, the basal activity of Mec1ATR is stimulated in a cell-cycle-dependent manner, leading to cell-cycle arrest and the promotion of DNA repair. Mec1ATR dysfunction leads to cell death in yeast and causes chromosome instability and embryonic lethality in mammals. Thus, ATR is a major target for cancer therapies in homologous recombination-deficient cancers. Here we identify a single mutation in Mec1, conserved in ATR, that results in constitutive activity. Using cryo-electron microscopy, we determine the structures of this constitutively active form (Mec1(F2244L)-Ddc2) at 2.8 Å and the wild type at 3.8 Å, both in complex with Mg2+-AMP-PNP. These structures yield a near-complete atomic model for Mec1-Ddc2 and uncover the molecular basis for low basal activity and the conformational changes required for activation. Combined with biochemical and genetic data, we discover key regulatory regions and propose a Mec1 activation mechanism.
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Affiliation(s)
- Elias A Tannous
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
| | - Luke A Yates
- Section of Structural Biology, Department of Infectious Disease, Imperial College London, South Kensington, London, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Infectious Disease, Imperial College London, South Kensington, London, UK.
| | - Peter M Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA.
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210
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Yang S, Zhang Y, Ting CY, Bettedi L, Kim K, Ghaniam E, Lilly MA. The Rag GTPase Regulates the Dynamic Behavior of TSC Downstream of Both Amino Acid and Growth Factor Restriction. Dev Cell 2020; 55:272-288.e5. [PMID: 32898476 PMCID: PMC7657977 DOI: 10.1016/j.devcel.2020.08.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/30/2020] [Accepted: 08/10/2020] [Indexed: 01/09/2023]
Abstract
The dysregulation of the metabolic regulator TOR complex I (TORC1) contributes to a wide array of human pathologies. Tuberous sclerosis complex (TSC) is a potent inhibitor of TORC1. Here, we demonstrate that the Rag GTPase acts in both the amino-acid-sensing and growth factor signaling pathways to control TORC1 activity through the regulation of TSC dynamics in HeLa cells and Drosophila. We find that TSC lysosomal-cytosolic exchange increases in response to both amino acid and growth factor restriction. Moreover, the rate of exchange mirrors TSC function, with depletions of the Rag GTPase blocking TSC lysosomal mobility and rescuing TORC1 activity. Finally, we show that the GATOR2 complex controls the phosphorylation of TSC2, which is essential for TSC exchange. Our data support the model that the amino acid and growth factor signaling pathways converge on the Rag GTPase to inhibit TORC1 activity through the regulation of TSC dynamics.
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Affiliation(s)
- Shu Yang
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yingbiao Zhang
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chun-Yuan Ting
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lucia Bettedi
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kuikwon Kim
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Elena Ghaniam
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mary A Lilly
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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211
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Yao Y, Hong S, Ikeda T, Mori H, MacDougald OA, Nada S, Okada M, Inoki K. Amino Acids Enhance Polyubiquitination of Rheb and Its Binding to mTORC1 by Blocking Lysosomal ATXN3 Deubiquitinase Activity. Mol Cell 2020; 80:437-451.e6. [PMID: 33157014 PMCID: PMC7665239 DOI: 10.1016/j.molcel.2020.10.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 08/22/2020] [Accepted: 10/02/2020] [Indexed: 01/02/2023]
Abstract
Amino-acid-induced lysosomal mechanistic target of rapamycin complex 1 (mTORC1) localization through the Rag GTPases is a critical step for its activation by Rheb GTPase. However, how the mTORC1 interacts with Rheb on the lysosome remains elusive. We report that amino acids enhance the polyubiquitination of Rheb (Ub-Rheb), which shows a strong binding preference for mTORC1 and supports its activation, while the Ub-Rheb is subjected to subsequent degradation. Mechanistically, we identified ATXN3 as a Ub-Rheb deubiquitinase whose lysosomal localization is blocked by active Rag heterodimer in response to amino acid stimulation. Consistently, cells lacking functional Rag heterodimer on the lysosome accumulate Ub-Rheb, and blockade of its degradation instigates robust lysosomal mTORC1 localization and its activation without the Ragulator-Rag system. Thus, polyubiquitination of Rheb is an important post-translational modification, which facilitates the binding of mTORC1 to Rheb on the lysosome and is another crosstalk between the amino acid and growth factor signaling for mTORC1 activation.
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Affiliation(s)
- Yao Yao
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA
| | - Sungki Hong
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA
| | - Takayuki Ikeda
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA; Department of Biochemistry, Kanazawa Medical University School of Medicine, 1-1 Daigaku, Uchinada, Kahoku-gun, Ishikawa 920-0293, Japan
| | - Hiroyuki Mori
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 E. Catherine St., Ann Arbor, MI 48109-5622, USA
| | - Ormond A MacDougald
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 E. Catherine St., Ann Arbor, MI 48109-5622, USA; Department of Internal Medicine, University of Michigan Medical School, 1500 East Medical Center Drive, Ann Arbor, MI 48109-5368, USA
| | - Shigeyuki Nada
- Department of Oncogene Research, the Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Masato Okada
- Department of Oncogene Research, the Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ken Inoki
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA; Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 E. Catherine St., Ann Arbor, MI 48109-5622, USA; Department of Internal Medicine, University of Michigan Medical School, 1500 East Medical Center Drive, Ann Arbor, MI 48109-5368, USA.
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212
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Hao P, Yu J, Ward R, Liu Y, Hao Q, An S, Xu T. Eukaryotic translation initiation factors as promising targets in cancer therapy. Cell Commun Signal 2020; 18:175. [PMID: 33148274 PMCID: PMC7640403 DOI: 10.1186/s12964-020-00607-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 06/01/2020] [Indexed: 02/08/2023] Open
Abstract
The regulation of the translation of messenger RNA (mRNA) in eukaryotic cells is critical for gene expression, and occurs principally at the initiation phase which is mainly regulated by eukaryotic initiation factors (eIFs). eIFs are fundamental for the translation of mRNA and as such act as the primary targets of several signaling pathways to regulate gene expression. Mis-regulated mRNA expression is a common feature of tumorigenesis and the abnormal activity of eIF complexes triggered by upstream signaling pathways is detected in many tumors, leading to the selective translation of mRNA encoding proteins involved in tumorigenesis, metastasis, or resistance to anti-cancer drugs, and making eIFs a promising therapeutic target for various types of cancers. Here, we briefly outline our current understanding of the biology of eIFs, mainly focusing on the effects of several signaling pathways upon their functions and discuss their contributions to the initiation and progression of tumor growth. An overview of the progress in developing agents targeting the components of translation machinery for cancer treatment is also provided. Video abstract
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Affiliation(s)
- Peiqi Hao
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, 727 Jingming South Road, Kunming, 650500, China.,Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, China
| | - Jiaojiao Yu
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, 727 Jingming South Road, Kunming, 650500, China
| | - Richard Ward
- Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, Scotland, UK
| | - Yin Liu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, China
| | - Qiao Hao
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, China
| | - Su An
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, China.
| | - Tianrui Xu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, China.
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213
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Scaiola A, Mangia F, Imseng S, Boehringer D, Berneiser K, Shimobayashi M, Stuttfeld E, Hall MN, Ban N, Maier T. The 3.2-Å resolution structure of human mTORC2. SCIENCE ADVANCES 2020; 6:6/45/eabc1251. [PMID: 33158864 PMCID: PMC7673708 DOI: 10.1126/sciadv.abc1251] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 09/22/2020] [Indexed: 05/22/2023]
Abstract
The protein kinase mammalian target of rapamycin (mTOR) is the central regulator of cell growth. Aberrant mTOR signaling is linked to cancer, diabetes, and neurological disorders. mTOR exerts its functions in two distinct multiprotein complexes, mTORC1 and mTORC2. Here, we report a 3.2-Å resolution cryo-EM reconstruction of mTORC2. It reveals entangled folds of the defining Rictor and the substrate-binding SIN1 subunits, identifies the carboxyl-terminal domain of Rictor as the source of the rapamycin insensitivity of mTORC2, and resolves mechanisms for mTORC2 regulation by complex destabilization. Two previously uncharacterized small-molecule binding sites are visualized, an inositol hexakisphosphate (InsP6) pocket in mTOR and an mTORC2-specific nucleotide binding site in Rictor, which also forms a zinc finger. Structural and biochemical analyses suggest that InsP6 and nucleotide binding do not control mTORC2 activity directly but rather have roles in folding or ternary interactions. These insights provide a firm basis for studying mTORC2 signaling and for developing mTORC2-specific inhibitors.
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Affiliation(s)
- Alain Scaiola
- Institute for Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Francesca Mangia
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Stefan Imseng
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | | | - Karolin Berneiser
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Mitsugu Shimobayashi
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Edward Stuttfeld
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Michael N Hall
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Nenad Ban
- Institute for Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland.
| | - Timm Maier
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland.
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214
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Teh AH, Yeap KH, Hisano T. Insights into DEPTOR regulation from in silico analysis of DEPTOR complexes. J Struct Biol 2020; 212:107602. [PMID: 32798656 DOI: 10.1016/j.jsb.2020.107602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/21/2020] [Accepted: 08/11/2020] [Indexed: 01/25/2023]
Abstract
DEPTOR is an inhibitor of the mTOR kinase which controls cell growth. DEPTOR consists of two DEP domains and a PDZ domain connected by an unstructured linker, and its stability is tightly regulated through post-translational modifications of its linker region that contains the 286SSGYFS291 degron. Based on the mTORC1 complex, our modelling suggests a possible spatial arrangement of DEPTOR which is characterised to form a dimer. Our model shows that the two PDZ domains of a DEPTOR dimer bind separately to the dimeric mTOR's FAT domains ~130 Å apart, while each of the two extended linkers is sufficiently long to span from the FAT domain to the kinase domain of mTOR and beyond to join a shared dimer of the DEP domains. This places the linker's S299 closest to the kinase's catalytic site, indicating that phosphorylation would start with it and successively upstream towards DEPTOR's degron. The CK1α kinase is reportedly responsible for the phosphorylation of the degron, and our docking analysis further reveals that CK1α contains sites to bind DEPTOR's pS286, pS287 and pT295, which may act as priming phosphates for the phosphorylation of the degron's S291. DEPTOR's linker can also be ubiquitylated by the UbcH5A-SCFβ-TrCP complex without its PDZ dissociating from mTOR according to the modelling. As the catalytic cleft of mTOR's kinase is restricted, interactions between the kinase's unstructured segment surrounding the cleft and DEPTOR's linker, which may involve S293 and S299, may be critical to controlling DEPTOR's access to the catalytic cleft and hence its phosphorylation by mTOR in a manner dependent on mTOR's activation.
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Affiliation(s)
- Aik-Hong Teh
- Centre for Chemical Biology, Universiti Sains Malaysia, 10 Persiaran Bukit Jambul, 11900 Penang, Malaysia; USM-RIKEN International Centre for Ageing Science (URICAS), Universiti Sains Malaysia, 11800 Penang, Malaysia.
| | - Kean-Heng Yeap
- Centre for Chemical Biology, Universiti Sains Malaysia, 10 Persiaran Bukit Jambul, 11900 Penang, Malaysia; USM-RIKEN International Centre for Ageing Science (URICAS), Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Tamao Hisano
- USM-RIKEN International Centre for Ageing Science (URICAS), Universiti Sains Malaysia, 11800 Penang, Malaysia; Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Kanagawa 230-0045, Japan
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215
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Benn CL, Dawson LA. Clinically Precedented Protein Kinases: Rationale for Their Use in Neurodegenerative Disease. Front Aging Neurosci 2020; 12:242. [PMID: 33117143 PMCID: PMC7494159 DOI: 10.3389/fnagi.2020.00242] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/13/2020] [Indexed: 12/12/2022] Open
Abstract
Kinases are an intensively studied drug target class in current pharmacological research as evidenced by the large number of kinase inhibitors being assessed in clinical trials. Kinase-targeted therapies have potential for treatment of a broad array of indications including central nervous system (CNS) disorders. In addition to the many variables which contribute to identification of a successful therapeutic molecule, drug discovery for CNS-related disorders also requires significant consideration of access to the target organ and specifically crossing the blood-brain barrier (BBB). To date, only a small number of kinase inhibitors have been reported that are specifically designed to be BBB permeable, which nonetheless demonstrates the potential for success. This review considers the potential for kinase inhibitors in the context of unmet medical need for neurodegenerative disease. A subset of kinases that have been the focus of clinical investigations over a 10-year period have been identified and discussed individually. For each kinase target, the data underpinning the validity of each in the context of neurodegenerative disease is critically evaluated. Selected molecules for each kinase are identified with information on modality, binding site and CNS penetrance, if known. Current clinical development in neurodegenerative disease are summarized. Collectively, the review indicates that kinase targets with sufficient rationale warrant careful design approaches with an emphasis on improving brain penetrance and selectivity.
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216
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Abstract
The Ras oncogene is notoriously difficult to target with specific therapeutics. Consequently, there is interest to better understand the Ras signaling pathways to identify potential targetable effectors. Recently, the mechanistic target of rapamycin complex 2 (mTORC2) was identified as an evolutionarily conserved Ras effector. mTORC2 regulates essential cellular processes, including metabolism, survival, growth, proliferation and migration. Moreover, increasing evidence implicate mTORC2 in oncogenesis. Little is known about the regulation of mTORC2 activity, but proposed mechanisms include a role for phosphatidylinositol (3,4,5)-trisphosphate - which is produced by class I phosphatidylinositol 3-kinases (PI3Ks), well-characterized Ras effectors. Therefore, the relationship between Ras, PI3K and mTORC2, in both normal physiology and cancer is unclear; moreover, seemingly conflicting observations have been reported. Here, we review the evidence on potential links between Ras, PI3K and mTORC2. Interestingly, data suggest that Ras and PI3K are both direct regulators of mTORC2 but that they act on distinct pools of mTORC2: Ras activates mTORC2 at the plasma membrane, whereas PI3K activates mTORC2 at intracellular compartments. Consequently, we propose a model to explain how Ras and PI3K can differentially regulate mTORC2, and highlight the diversity in the mechanisms of mTORC2 regulation, which appear to be determined by the stimulus, cell type, and the molecularly and spatially distinct mTORC2 pools.
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217
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Saftig P, Puertollano R. How Lysosomes Sense, Integrate, and Cope with Stress. Trends Biochem Sci 2020; 46:97-112. [PMID: 33012625 DOI: 10.1016/j.tibs.2020.09.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/07/2020] [Accepted: 09/08/2020] [Indexed: 12/17/2022]
Abstract
Lysosomes are in the center of the cellular control of catabolic and anabolic processes. These membrane-surrounded acidic organelles contain around 70 hydrolases, 200 membrane proteins, and numerous accessory proteins associated with the cytosolic surface of lysosomes. Accessory and transmembrane proteins assemble in signaling complexes that sense and integrate multiple signals and transmit the information to the nucleus. This communication allows cells to respond to changes in multiple environmental conditions, including nutrient levels, pathogens, energy availability, and lysosomal damage, with the goal of restoring cellular homeostasis. This review summarizes our current understanding of the major molecular players and known pathways that are involved in control of metabolic and stress responses that either originate from lysosomes or regulate lysosomal functions.
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Affiliation(s)
- Paul Saftig
- Biochemical Institute, Christian-Albrechts-Universität Kiel, Kiel, Germany.
| | - Rosa Puertollano
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Bethesda, MD 20892, USA.
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218
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Texada MJ, Koyama T, Rewitz K. Regulation of Body Size and Growth Control. Genetics 2020; 216:269-313. [PMID: 33023929 PMCID: PMC7536854 DOI: 10.1534/genetics.120.303095] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/29/2020] [Indexed: 12/20/2022] Open
Abstract
The control of body and organ growth is essential for the development of adults with proper size and proportions, which is important for survival and reproduction. In animals, adult body size is determined by the rate and duration of juvenile growth, which are influenced by the environment. In nutrient-scarce environments in which more time is needed for growth, the juvenile growth period can be extended by delaying maturation, whereas juvenile development is rapidly completed in nutrient-rich conditions. This flexibility requires the integration of environmental cues with developmental signals that govern internal checkpoints to ensure that maturation does not begin until sufficient tissue growth has occurred to reach a proper adult size. The Target of Rapamycin (TOR) pathway is the primary cell-autonomous nutrient sensor, while circulating hormones such as steroids and insulin-like growth factors are the main systemic regulators of growth and maturation in animals. We discuss recent findings in Drosophila melanogaster showing that cell-autonomous environment and growth-sensing mechanisms, involving TOR and other growth-regulatory pathways, that converge on insulin and steroid relay centers are responsible for adjusting systemic growth, and development, in response to external and internal conditions. In addition to this, proper organ growth is also monitored and coordinated with whole-body growth and the timing of maturation through modulation of steroid signaling. This coordination involves interorgan communication mediated by Drosophila insulin-like peptide 8 in response to tissue growth status. Together, these multiple nutritional and developmental cues feed into neuroendocrine hubs controlling insulin and steroid signaling, serving as checkpoints at which developmental progression toward maturation can be delayed. This review focuses on these mechanisms by which external and internal conditions can modulate developmental growth and ensure proper adult body size, and highlights the conserved architecture of this system, which has made Drosophila a prime model for understanding the coordination of growth and maturation in animals.
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Affiliation(s)
| | - Takashi Koyama
- Department of Biology, University of Copenhagen, 2100, Denmark
| | - Kim Rewitz
- Department of Biology, University of Copenhagen, 2100, Denmark
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219
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Luciani A, Stagi M. How mTORC1 makes sense of nutrients. Kidney Int 2020; 99:295-298. [PMID: 33010258 DOI: 10.1016/j.kint.2020.07.052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 07/23/2020] [Indexed: 10/23/2022]
Affiliation(s)
- Alessandro Luciani
- Mechanisms of Inherited Kidney Diseases Group, Institute of Physiology, University of Zurich, Zurich, Switzerland.
| | - Massimiliano Stagi
- Department of Molecular Physiology & Cell Signalling, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, UK
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220
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Hammel M, Rosenberg DJ, Bierma J, Hura GL, Thapar R, Lees-Miller SP, Tainer JA. Visualizing functional dynamicity in the DNA-dependent protein kinase holoenzyme DNA-PK complex by integrating SAXS with cryo-EM. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 163:74-86. [PMID: 32966823 DOI: 10.1016/j.pbiomolbio.2020.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 08/19/2020] [Accepted: 09/17/2020] [Indexed: 12/27/2022]
Abstract
Assembly of KU and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) at DNA double strand breaks (DSBs) forms DNA-PK holoenzyme as a critical initiating step for non-homologous end joining (NHEJ) repair of DSBs produced by radiation and chemotherapies. Advanced cryo-electron microscopy (cryo-EM) imaging together with breakthrough macromolecular X-ray crystal (MX) structures of KU and DNA-PKcs recently enabled visualization of the ∼600 kDa DNA-PK assembly at near atomic resolution. These important static structures provide the foundation for definition and interpretation of functional movements crucial to mechanistic understanding that can be tested through solution state structure analysis. We herein therefore leverage Cryo-EM and MX structures for the interpretation of synchrotron small-angle X-ray scattering (SAXS) data on DNA-PK conformations in solution to inform the structural mechanism for NHEJ initiation. SAXS, which measures thermodynamic solution-state conformational states and assemblies outside of cryo- and solid-state conditions, unveils the inherent flexibility of KU, DNA-PKcs and DNA-PK. The combined structural measurements reveal mobility of KU80 C-terminal region (KU80CTR), motion/plasticity of HEAT (DNA-PKcs Huntingtin, Elongation Factor 3, PP2 A, and TOR1) regions, allosteric switching upon DNA-PKcs autophosphorylation, and dimeric arrangements of DNA-PK assembly. Importantly, the results uncover displacement of the N-terminal HEAT domain during autophosphorylation as suitable for a regulated release mechanism of DNA-PKcs from DNA-PK to control unproductive access to toxic and mutagenic DNA repair intermediates. These integrated analyses show that the marriage of SAXS with cryo-EM leverages the strengths of both techniques to enable assessment of functional conformations and flexibility defining atomic-resolution molecular mechanisms for DSB repair.
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Affiliation(s)
- Michal Hammel
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Daniel J Rosenberg
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA; Graduate Group in Biophysics, University of California, Berkeley, CA, 94720, USA
| | - Jan Bierma
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Gregory L Hura
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Roopa Thapar
- Department of Cancer Biology, Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, University of Calgary, Alberta, T2N 4N1, Canada
| | - John A Tainer
- Department of Cancer Biology, Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
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221
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Persistent Rheb-induced mTORC1 activation in spinal cord neurons induces hypersensitivity in neuropathic pain. Cell Death Dis 2020; 11:747. [PMID: 32920594 PMCID: PMC7487067 DOI: 10.1038/s41419-020-02966-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 08/21/2020] [Accepted: 08/31/2020] [Indexed: 12/21/2022]
Abstract
The small GTPase Ras homolog enriched in the brain (Rheb) can activate mammalian target of rapamycin (mTOR) and regulate the growth and cell cycle progression. We investigated the role of Rheb-mediated mTORC1 signaling in neuropathic pain. A chronic constriction injury (CCI) model was dopted. CCI induced obvious spinal Rheb expression and phosphorylation of mTOR, S6, and 4-E-BP1. Blocking mTORC1 signal with rapamycin alleviated the neuropathic pain and restored morphine efficacy in CCI model. Immunofluoresence showed a neuronal co-localization of CCI-induced Rheb and pS6. Rheb knockin mouse showed a similar behavioral phenotype as CCI. In spinal slice recording, CCI increased the firing frequency of neurons expressing HCN channels; inhibition of mTORC1 with rapamycin could reverse the increased spinal neuronal activity in neuropathic pain. Spinal Rheb is induced in neuropathic pain, which in turn active the mTORC1 signaling in CCI. Spinal Rheb-mTOR signal plays an important role in regulation of spinal sensitization in neuropathic pain, and targeting mTOR may give a new strategy for pain management.
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222
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Zhang C, Liu Y, Zhang Y, Wang X, Zhang T, Ding J. Molecular basis for the functions of dominantly active Y35N and inactive D60K Rheb mutants in mTORC1 signaling. J Mol Cell Biol 2020; 12:741-744. [PMID: 32470140 PMCID: PMC7749741 DOI: 10.1093/jmcb/mjaa025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/05/2020] [Accepted: 05/25/2020] [Indexed: 11/18/2022] Open
Affiliation(s)
- Chunxiao Zhang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yan Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yifang Zhang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiangxiang Wang
- School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Tianlong Zhang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jianping Ding
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China.,School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
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223
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Jang YG, Choi Y, Jun K, Chung J. Mislocalization of TORC1 to Lysosomes Caused by KIF11 Inhibition Leads to Aberrant TORC1 Activity. Mol Cells 2020; 43:705-717. [PMID: 32759469 PMCID: PMC7468583 DOI: 10.14348/molcells.2020.0089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/15/2020] [Accepted: 06/24/2020] [Indexed: 01/15/2023] Open
Abstract
While the growth factors like insulin initiate a signaling cascade to induce conformational changes in the mechanistic target of rapamycin complex 1 (mTORC1), amino acids cause the complex to localize to the site of activation, the lysosome. The precise mechanism of how mTORC1 moves in and out of the lysosome is yet to be elucidated in detail. Here we report that microtubules and the motor protein KIF11 are required for the proper dissociation of mTORC1 from the lysosome upon amino acid scarcity. When microtubules are disrupted or KIF11 is knocked down, we observe that mTORC1 localizes to the lysosome even in the amino acid-starved situation where it should be dispersed in the cytosol, causing an elevated mTORC1 activity. Moreover, in the mechanistic perspective, we discover that mTORC1 interacts with KIF11 on the motor domain of KIF11, enabling the complex to move out of the lysosome along microtubules. Our results suggest not only a novel way of the regulation regarding amino acid availability for mTORC1, but also a new role of KIF11 and microtubules in mTOR signaling.
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Affiliation(s)
- Yoon-Gu Jang
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Korea
- School of Biological Sciences, Seoul National University, Seoul 0886, Korea
- These authors contributed equally to this work.
| | - Yujin Choi
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Korea
- School of Biological Sciences, Seoul National University, Seoul 0886, Korea
- These authors contributed equally to this work.
| | - Kyoungho Jun
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Korea
- School of Biological Sciences, Seoul National University, Seoul 0886, Korea
| | - Jongkyeong Chung
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Korea
- School of Biological Sciences, Seoul National University, Seoul 0886, Korea
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224
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Melick CH, Jewell JL. Regulation of mTORC1 by Upstream Stimuli. Genes (Basel) 2020; 11:genes11090989. [PMID: 32854217 PMCID: PMC7565831 DOI: 10.3390/genes11090989] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/22/2020] [Accepted: 08/23/2020] [Indexed: 01/08/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) is an evolutionary conserved Ser/Thr protein kinase that senses multiple upstream stimuli to control cell growth, metabolism, and autophagy. mTOR is the catalytic subunit of mTOR complex 1 (mTORC1). A significant amount of research has uncovered the signaling pathways regulated by mTORC1, and the involvement of these signaling cascades in human diseases like cancer, diabetes, and ageing. Here, we review advances in mTORC1 regulation by upstream stimuli. We specifically focus on how growth factors, amino acids, G-protein coupled receptors (GPCRs), phosphorylation, and small GTPases regulate mTORC1 activity and signaling.
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Affiliation(s)
- Chase H. Melick
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA;
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jenna L. Jewell
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA;
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Correspondence:
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225
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Huang L, Peng B, Nayak Y, Wang C, Si F, Liu X, Dou J, Xu H, Peng G. Baicalein and Baicalin Promote Melanoma Apoptosis and Senescence via Metabolic Inhibition. Front Cell Dev Biol 2020; 8:836. [PMID: 32984331 PMCID: PMC7477299 DOI: 10.3389/fcell.2020.00836] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/04/2020] [Indexed: 12/22/2022] Open
Abstract
Malignant melanoma is one of the most common and dangerous skin cancers with a high rate of death every year. Furthermore, N-RAS and B-RAF mutations in melanoma cells increase the difficulties for clinical treatment in patients. Therefore, development of effective and universal drugs against melanoma is urgently needed. Here we demonstrate that baicalein and baicalin, the active components of the Chinese traditional medicinal plant Scutellaria baicalensis Georgi, can significantly inhibit melanoma cell growth and proliferation, suppress tumor cell colony formation and migration, as well as induce apoptosis and senescence in melanoma cells. The anti-tumor effects mediated by baicalein and baicalin are independent of N-RAS and B-RAF mutation statuses in melanoma cells. Mechanistically, we identify that the suppression of baicalein and baicalin on melanoma cells is due to inhibition of tumor cell glucose uptake and metabolism by affecting the mTOR-HIF-1α signaling pathway. In addition, we demonstrated that baicalein and baicalin can suppress tumorigenesis and tumor growth in vivo in the melanoma model. These studies clearly indicate that baicalein and baicalin can control tumor growth and development metabolically and have great potential as novel and universal drugs for melanoma therapy.
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Affiliation(s)
- Lan Huang
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, China.,Division of Infectious Diseases, Allergy and Immunology, Department of Internal Medicine, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Bo Peng
- Division of Infectious Diseases, Allergy and Immunology, Department of Internal Medicine, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Yash Nayak
- Division of Infectious Diseases, Allergy and Immunology, Department of Internal Medicine, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Cindy Wang
- Division of Infectious Diseases, Allergy and Immunology, Department of Internal Medicine, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Fusheng Si
- Division of Infectious Diseases, Allergy and Immunology, Department of Internal Medicine, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Xia Liu
- Division of Infectious Diseases, Allergy and Immunology, Department of Internal Medicine, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Jie Dou
- State Key Laboratory of Natural Medicines, School of Life Sciences and Technology, China Pharmaceutical University, Nanjing, China
| | - Huaxi Xu
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, China
| | - Guangyong Peng
- Division of Infectious Diseases, Allergy and Immunology, Department of Internal Medicine, School of Medicine, Saint Louis University, St. Louis, MO, United States
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Metformin Suppresses Development of the Echinococcus multilocularis Larval Stage by Targeting the TOR Pathway. Antimicrob Agents Chemother 2020; 64:AAC.01808-19. [PMID: 32540980 DOI: 10.1128/aac.01808-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 06/08/2020] [Indexed: 02/06/2023] Open
Abstract
Alveolar echinococcosis (AE) is a severe disease caused by the larval stage of the tapeworm Echinococcus multilocularis Current chemotherapeutic treatment options based on benzimidazoles are of limited effectiveness, which underlines the need to find new antiechinococcosis drugs. Metformin is an antihyperglycemic and antiproliferative agent that shows activity against the related parasite Echinococcus granulosus Hence, we assessed the in vitro and in vivo effects of the drug on E. multilocularis Metformin exerted significant dose-dependent killing effects on in vitro cultured parasite stem cells and protoscoleces and significantly reduced the dedifferentiation of protoscoleces into metacestodes. Likewise, oral administration of metformin (50 mg/kg of body weight/day for 8 weeks) was effective in achieving a significant reduction of parasite weight in a secondary murine AE model. Our results revealed mitochondrial membrane depolarization, activation of Em-AMPK, suppression of Em-TOR, and overexpression of Em-Atg8 in the germinal layer of metformin-treated metacestode vesicles. The opposite effects on the level of active Em-TOR in response to exogenous insulin and rapamycin suggest that Em-TOR is part of the parasite's insulin signaling pathway. Finally, the presence of the key lysosomal pathway components, through which metformin reportedly acts, was confirmed in the parasite by in silico assays. Taken together, these results introduce metformin as a promising candidate for AE treatment. Although our study highlights the importance of those direct mechanisms by which metformin reduces parasite viability, it does not necessarily preclude any additional systemic effects of the drug that might reduce parasite growth in vivo.
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227
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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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228
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Dumas SN, Lamming DW. Next Generation Strategies for Geroprotection via mTORC1 Inhibition. J Gerontol A Biol Sci Med Sci 2020; 75:14-23. [PMID: 30794726 DOI: 10.1093/gerona/glz056] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Indexed: 01/10/2023] Open
Abstract
Inhibition of mTORC1 (mechanistic Target Of Rapamycin Complex 1) with the pharmaceutical rapamycin prolongs the lifespan and healthspan of model organisms including rodents, with evidence now emerging that rapamycin and its analogs may also have rejuvenative effects in dogs and humans. However, the side effects associated with long-term rapamycin treatment, many of which are due to inhibition of a second mTOR complex, mTORC2, have seemed to preclude the routine use of rapamycin as a therapy for age-related diseases. Here, we discuss recent findings suggesting that strong, chronic inhibition of both mTOR complexes may not be necessary to realize the geroprotective effects of rapamycin. Instead, modestly but specifically inhibiting mTORC1 via a variety of emerging techniques, including intermittent or transient treatment with rapamycin derivatives, or specific dietary regimens, may be sufficient to promote health and longevity with reduced side effects. We will also discuss prospects for the development of new molecules that, by harnessing the detailed molecular understanding of mTORC1 signaling developed over the last decade, will provide new routes to the selective inhibition of mTORC1. We conclude that therapies based on the selective inhibition of mTORC1 may soon permit the safer treatment of diseases of aging.
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Affiliation(s)
- Sabrina N Dumas
- William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin.,Department of Medicine, University of Wisconsin-Madison
| | - Dudley W Lamming
- William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin.,Department of Medicine, University of Wisconsin-Madison
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229
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Choi S, Kim H. The Remedial Potential of Lycopene in Pancreatitis through Regulation of Autophagy. Int J Mol Sci 2020; 21:ijms21165775. [PMID: 32806545 PMCID: PMC7460830 DOI: 10.3390/ijms21165775] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 08/05/2020] [Accepted: 08/11/2020] [Indexed: 12/12/2022] Open
Abstract
Autophagy is an evolutionarily conserved process that degrades damaged organelles and recycles macromolecules to support cell survival. However, in certain disease states, dysregulated autophagy can play an important role in cell death. In pancreatitis, the accumulation of autophagic vacuoles and damaged mitochondria and premature activation of trypsinogen are shown in pancreatic acinar cells (PACs), which are the hallmarks of impaired autophagy. Oxidative stress mediates inflammatory signaling and cytokine expression in PACs, and it also causes mitochondrial dysfunction and dysregulated autophagy. Thus, oxidative stress may be a mediator for autophagic impairment in pancreatitis. Lycopene is a natural pigment that contributes to the red color of fruits and vegetables. Due to its antioxidant activity, it inhibited oxidative stress-induced expression of cytokines in experimental models of acute pancreatitis. Lycopene reduces cell death through the activation of 5′-AMP-activated protein kinase-dependent autophagy in certain cells. Therefore, lycopene may ameliorate pancreatitis by preventing oxidative stress-induced impairment of autophagy and/or by directly activating autophagy in PACs.
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230
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Tafur L, Kefauver J, Loewith R. Structural Insights into TOR Signaling. Genes (Basel) 2020; 11:E885. [PMID: 32759652 PMCID: PMC7464330 DOI: 10.3390/genes11080885] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/31/2020] [Accepted: 08/02/2020] [Indexed: 12/31/2022] Open
Abstract
The Target of Rapamycin (TOR) is a highly conserved serine/threonine protein kinase that performs essential roles in the control of cellular growth and metabolism. TOR acts in two distinct multiprotein complexes, TORC1 and TORC2 (mTORC1 and mTORC2 in humans), which maintain different aspects of cellular homeostasis and orchestrate the cellular responses to diverse environmental challenges. Interest in understanding TOR signaling is further motivated by observations that link aberrant TOR signaling to a variety of diseases, ranging from epilepsy to cancer. In the last few years, driven in large part by recent advances in cryo-electron microscopy, there has been an explosion of available structures of (m)TORC1 and its regulators, as well as several (m)TORC2 structures, derived from both yeast and mammals. In this review, we highlight and summarize the main findings from these reports and discuss both the fascinating and unexpected molecular biology revealed and how this knowledge will potentially contribute to new therapeutic strategies to manipulate signaling through these clinically relevant pathways.
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Affiliation(s)
- Lucas Tafur
- Department of Molecular Biology, University of Geneva, 30 quai Ernest-Ansermet, CH1211 Geneva, Switzerland; (L.T.); (J.K.)
| | - Jennifer Kefauver
- Department of Molecular Biology, University of Geneva, 30 quai Ernest-Ansermet, CH1211 Geneva, Switzerland; (L.T.); (J.K.)
| | - Robbie Loewith
- Department of Molecular Biology, University of Geneva, 30 quai Ernest-Ansermet, CH1211 Geneva, Switzerland; (L.T.); (J.K.)
- Swiss National Centre for Competence in Research (NCCR) in Chemical Biology, University of Geneva, Sciences II, Room 3-308, 30 Quai Ernest-Ansermet, CH1211 Geneva, Switzerland
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231
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Liu Y, Zheng Y, Zhou Y, Liu Y, Xie M, Meng W, An M. The expression and significance of mTORC1 in diabetic retinopathy. BMC Ophthalmol 2020; 20:297. [PMID: 32689970 PMCID: PMC7370483 DOI: 10.1186/s12886-020-01553-3] [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: 11/22/2019] [Accepted: 07/06/2020] [Indexed: 01/23/2023] Open
Abstract
Background To investigate the expression and significance of mechanistic target of rapamycin complex 1(mTORC1) in diabetic retinopathy (DR), and to find new targets and new methods for the treatment of DR. Methods A DR rat model was prepared by general feeding combined with intraperitoneal injection of 10% streptozotocin (60 mg/kg). The rats were randomly divided into a control group (NDM group) and a diabetes group (DM group). Three months later, the degrees of retinopathy was determined using hematoxylin and eosin staining, and the levels of p-S6, VEGF, and PEDF proteins were detected by immunohistochemistry and western blotting. Human retinal capillary endothelial cells (HRCECs) were cultured in high glucose (HG) conditions, then treated with rapamycin or transfected with siTSC1.The protein levels of p-S6 were assessed by western blotting. The 5-ethynyl-2′-deoxyuridine assay was used to detect cell proliferation, and the Transwell assay was used to detect cell migration. Results A DM rat model was successfully developed. The expressions of p-S6 and VEGF proteins were significantly increased in the DM group (p < 0.05), and the expression of PEDF protein was significantly decreased compared with the NDM group (p < 0.05). In vitro, the p-S6 protein, as well as cell proliferation and migration, in HG induced HRCECs were increased (p < 0.05) compared with the control (normal glucose) group (p < 0.05). After transfection with siTSC1 to activate mTORC1, the expression of p-S6, as well as cell proliferation and migration, were increased. In contrast, rapamycin decreased p-S6 expression, as well as proliferation and migration, in HG induced HRCECs compared to the control group (p < 0.05). Conclusion mTORC1 plays an important role in DR. After activation, mTORC1 induced expression of the p-S6 protein, regulated the expressions of VEGF and PEDF proteins, and changed the proliferation and migration of endothelial cells. The mTORC1 can therefore be used as a new target,as well as in the treatment of DR.
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Affiliation(s)
- Yanli Liu
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Yarong Zheng
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Yekai Zhou
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Yi Liu
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Mengxuan Xie
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Wenjing Meng
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Meixia An
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China. .,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China.
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232
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N-myristoyltransferase-1 is necessary for lysosomal degradation and mTORC1 activation in cancer cells. Sci Rep 2020; 10:11952. [PMID: 32686708 PMCID: PMC7371688 DOI: 10.1038/s41598-020-68615-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 06/25/2020] [Indexed: 12/31/2022] Open
Abstract
N-myristoyltransferase-1 (NMT1) catalyzes protein myristoylation, a lipid modification that is elevated in cancer cells. NMT1 sustains proliferation and/or survival of cancer cells through mechanisms that are not completely understood. We used genetic and pharmacological inhibition of NMT1 to further dissect the role of this enzyme in cancer, and found an unexpected essential role for NMT1 at promoting lysosomal metabolic functions. Lysosomes mediate enzymatic degradation of vesicle cargo, and also serve as functional platforms for mTORC1 activation. We show that NMT1 is required for both lysosomal functions in cancer cells. Inhibition of NMT1 impaired lysosomal degradation leading to autophagy flux blockade, and simultaneously caused the dissociation of mTOR from the surface of lysosomes leading to decreased mTORC1 activation. The regulation of lysosomal metabolic functions by NMT1 was largely mediated through the lysosomal adaptor LAMTOR1. Accordingly, genetic targeting of LAMTOR1 recapitulated most of the lysosomal defects of targeting NMT1, including defective lysosomal degradation. Pharmacological inhibition of NMT1 reduced tumor growth, and tumors from treated animals had increased apoptosis and displayed markers of lysosomal dysfunction. Our findings suggest that compounds targeting NMT1 may have therapeutic benefit in cancer by preventing mTORC1 activation and simultaneously blocking lysosomal degradation, leading to cancer cell death.
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233
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Zhu Y, Wang R, Chen W, Chen Q, Zhou J. Construction of a prognosis-predicting model based on autophagy-related genes for hepatocellular carcinoma (HCC) patients. Aging (Albany NY) 2020; 12:14582-14592. [PMID: 32681721 PMCID: PMC7425489 DOI: 10.18632/aging.103507] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 06/04/2020] [Indexed: 12/13/2022]
Abstract
Background: Autophagy, a highly conserved cellular catabolic process by which the eukaryotic cells deliver autophagosomes engulfing cellular proteins and organelles to lysosomes for degradation, is critical for maintaining cellular homeostasis in response to various signals and nutrient stresses. The dysregulation of autophagy has been noted in the pathogenesis of cancers. Our study aims to investigate the prognosis-predicting value of autophagy-related genes (ARG) in hepatocellular carcinoma (HCC). Results: The signature was constructed based on eight ARGs, which stratified HCC patients into high- and low-risk groups in terms of overall survival (OS) (Hazard Ratio, HR=4.641, 95% Confidential Interval, CI, 3.365-5.917, P=0.000). The ARG signature is an independent prognostic indicator for HCC patients (HR = 1.286, 95% CI, 1.194-1.385; P < 0.001). The area under the receiver operating characteristic (ROC) curve (AUC) for 5-year survival is 0.765. Conclusion: This study provides a potential prognostic signature for predicting the prognosis of HCC patients and molecular insights into the significance of autophagy in HCC. Methods: Sixty-two differentially expressed ARGs and the clinical characteristics and basic information of the 369 enrolled HCC patients were retrieved from The Cancer Genome Atlas (TCGA) database. the Cox proportional hazard regression analysis was adopted to identify survival-related ARGs, based on which a prognosis predicting signature was constructed.
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Affiliation(s)
- Yayun Zhu
- Department of Liver Surgery and Transplantation, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Ru Wang
- Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Department of Breast Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Wanbin Chen
- Department of Marketing, The Johns Hopkins University Carey Business School, Baltimore, MD 21202, USA
| | - Qiuyu Chen
- Department of Clinical Immunology, Children's Hospital of Fudan University, Shanghai, China
| | - Jian Zhou
- Department of Liver Surgery and Transplantation, Liver Cancer Institute and State Key Laboratory of Genetic Engineering, Fudan University, Shanghai, China.,Key Laboratory of Carcinogenesis and Cancer Invasion, Fudan University, Ministry of Education, Shanghai, China.,Institute of Biomedical Sciences, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Organ Transplantation, Zhongshan Hospital, Fudan University, Shanghai, China
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234
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Powers KT, Szeto JYA, Schaffitzel C. New insights into no-go, non-stop and nonsense-mediated mRNA decay complexes. Curr Opin Struct Biol 2020; 65:110-118. [PMID: 32688260 DOI: 10.1016/j.sbi.2020.06.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 06/10/2020] [Accepted: 06/18/2020] [Indexed: 11/26/2022]
Abstract
Eukaryotes possess a variety of translational control mechanisms which function in the surveillance of mRNAs, discriminating between normal and aberrant translation elongation and termination, triggering mRNA decay. The three major evolutionarily conserved eukaryotic pathways are No-Go, Non-Stop and Nonsense-Mediated mRNA Decay. Recent findings suggest that stalling of the ribosome, due to mRNA secondary structure or translation into poly(A)-stretches, leads to ribosome collisions which are detected by No-Go/Non-Stop mRNA decay factors. Subsequent ribosome ubiquitination at the interface of two collided ribosomes is considered the signal for mRNA decay. Similarly, translation termination at a premature stop codon is slower than normal, leading to recruitment and activation of nonsense-mediated mRNA decay factors, including SMG1-8-9. Here, we detail new insights into the molecular mechanisms of these pathways.
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Affiliation(s)
- Kyle T Powers
- University of Bristol, School of Biochemistry, University Walk, Bristol, BS8 1TD, United Kingdom
| | - Jenn-Yeu Alvin Szeto
- University of Bristol, School of Biochemistry, University Walk, Bristol, BS8 1TD, United Kingdom
| | - Christiane Schaffitzel
- University of Bristol, School of Biochemistry, University Walk, Bristol, BS8 1TD, United Kingdom.
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235
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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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236
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Qian J, Su S, Liu P. Experimental Approaches in Delineating mTOR Signaling. Genes (Basel) 2020; 11:E738. [PMID: 32630768 PMCID: PMC7397015 DOI: 10.3390/genes11070738] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 06/28/2020] [Accepted: 06/30/2020] [Indexed: 11/16/2022] Open
Abstract
The mTOR signaling controls essential biological functions including proliferation, growth, metabolism, autophagy, ageing, and others. Hyperactivation of mTOR signaling leads to a plethora of human disorders; thus, mTOR is an attractive drug target. The discovery of mTOR signaling started from isolation of rapamycin in 1975 and cloning of TOR genes in 1993. In the past 27 years, numerous research groups have contributed significantly to advancing our understanding of mTOR signaling and mTOR biology. Notably, a variety of experimental approaches have been employed in these studies to identify key mTOR pathway members that shape up the mTOR signaling we know today. Technique development drives mTOR research, while canonical biochemical and yeast genetics lay the foundation for mTOR studies. Here in this review, we summarize major experimental approaches used in the past in delineating mTOR signaling, including biochemical immunoprecipitation approaches, genetic approaches, immunofluorescence microscopic approaches, hypothesis-driven studies, protein sequence or motif search driven approaches, and bioinformatic approaches. We hope that revisiting these distinct types of experimental approaches will provide a blueprint for major techniques driving mTOR research. More importantly, we hope that thinking and reasonings behind these experimental designs will inspire future mTOR research as well as studies of other protein kinases beyond mTOR.
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Affiliation(s)
- Jiayi Qian
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.Q.); (S.S.)
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Siyuan Su
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.Q.); (S.S.)
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Pengda Liu
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.Q.); (S.S.)
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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237
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Losiewicz MK, Elghazi L, Fingar DC, Rajala RVS, Lentz SI, Fort PE, Abcouwer SF, Gardner TW. mTORC1 and mTORC2 expression in inner retinal neurons and glial cells. Exp Eye Res 2020; 197:108131. [PMID: 32622801 DOI: 10.1016/j.exer.2020.108131] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/09/2020] [Accepted: 06/24/2020] [Indexed: 02/06/2023]
Abstract
The retina is one of the most metabolically active tissues, yet the processes that control retinal metabolism remains poorly understood. The mTOR complex (mTORC) that drives protein and lipid biogenesis and autophagy has been studied extensively in regards to retinal development and responses to optic nerve injury but the processes that regulate homeostasis in the adult retina have not been determined. We previously demonstrated that normal adult retina has high rates of protein synthesis compared to skeletal muscle, associated with high levels of mechanistic target of rapamycin (mTOR), a kinase that forms multi-subunit complexes that sense and integrate diverse environmental cues to control cell and tissue physiology. This study was undertaken to: 1) quantify expression of mTOR complex 1 (mTORC1)- and mTORC2-specific partner proteins in normal adult rat retina, brain and liver; and 2) to localize these components in normal human, rat, and mouse retinas. Immunoblotting and immunoprecipitation studies revealed greater expression of raptor (exclusive to mTORC1) and rictor (exclusive for mTORC2) in normal rat retina relative to liver or brain, as well as the activating mTORC components, pSIN1 and pPRAS40. By contrast, liver exhibits greater amounts of the mTORC inhibitor, DEPTOR. Immunolocalization studies for all three species showed that mTOR, raptor, and rictor, as well as most other known components of mTORC1 and mTORC2, were primarily localized in the inner retina with mTORC1 primarily in retinal ganglion cells (RGCs) and mTORC2 primarily in glial cells. In addition, phosphorylated ribosomal protein S6, a direct target of the mTORC1 substrate ribosomal protein S6 kinase beta-1 (S6K1), was readily detectable in RGCs, indicating active mTORC1 signaling, and was preserved in human donor eyes. Collectively, this study demonstrates that the inner retina expresses high levels of mTORC1 and mTORC2 and possesses active mTORC1 signaling that may provide cell- and tissue-specific regulation of homeostatic activity. These findings help to define the physiology of the inner retina, which is key for understanding the pathophysiology of optic neuropathies, glaucoma and diabetic retinopathy.
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Affiliation(s)
| | | | | | - Raju V S Rajala
- Departments of Ophthalmology and Physiology, University of Oklahoma Health Sciences Center, United States
| | - Stephen I Lentz
- Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, United States
| | - Patrice E Fort
- Ophthalmology & Visual Sciences, United States; Molecular and Integrative Physiology, University of Michigan Medical School, United States
| | | | - Thomas W Gardner
- Ophthalmology & Visual Sciences, United States; Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, United States; Molecular and Integrative Physiology, University of Michigan Medical School, United States.
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238
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Napolitano G, Di Malta C, Esposito A, de Araujo MEG, Pece S, Bertalot G, Matarese M, Benedetti V, Zampelli A, Stasyk T, Siciliano D, Venuta A, Cesana M, Vilardo C, Nusco E, Monfregola J, Calcagnì A, Di Fiore PP, Huber LA, Ballabio A. A substrate-specific mTORC1 pathway underlies Birt-Hogg-Dubé syndrome. Nature 2020; 585:597-602. [PMID: 32612235 PMCID: PMC7610377 DOI: 10.1038/s41586-020-2444-0] [Citation(s) in RCA: 166] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 04/27/2020] [Indexed: 12/17/2022]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is a key metabolic hub that controls the cellular response to environmental cues by exerting its kinase activity on multiple substrates1–3. However, whether mTORC1 responds to diverse stimuli by differentially phosphorylating specific substrates is poorly understood. Here we show that Transcription Factor EB (TFEB), a master regulator of lysosomal biogenesis and autophagy4,5, is phosphorylated by mTORC1 via a substrate-specific mechanism mediated by RagGTPases. Thus, TFEB phosphorylation is strictly dependent on amino acid-mediated activation of RagC/D GTPase but, unlike other mTORC1 substrates such as S6K and 4E-BP1, insensitive to growth factor-induced Rheb activity. This mechanism plays a crucial role in Birt-Hogg-Dubé (BHD) syndrome, a disorder caused by mutations of the RagC/D activator folliculin (FLCN) and characterized by benign skin tumors, lung and kidney cysts and renal cell carcinoma6,7. We found that constitutive activation of TFEB is the main driver of the kidney abnormalities and paradoxical mTORC1 hyperactivity observed in BHD syndrome. Remarkably, depletion of TFEB in a kidney-specific mouse model of BHD syndrome fully rescued the disease phenotype and associated lethality and normalized mTORC1 activity. Together, these findings identify a substrate-specific control mechanism of mTORC1, whose dysregulation leads to kidney cysts and cancer.
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Affiliation(s)
- Gennaro Napolitano
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy.,Medical Genetics Unit, Department of Medical and Translational Science, Federico II University, Naples, Italy
| | - Chiara Di Malta
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | | | - Mariana E G de Araujo
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Salvatore Pece
- IEO, European Institute of Oncology IRCCS, Milan, Italy.,Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
| | | | - Maria Matarese
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | | | - Angela Zampelli
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Taras Stasyk
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | | | | | - Marcella Cesana
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Claudia Vilardo
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Edoardo Nusco
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | | | - Alessia Calcagnì
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Pier Paolo Di Fiore
- IEO, European Institute of Oncology IRCCS, Milan, Italy.,Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
| | - Lukas A Huber
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.,Austrian Drug Screening Institute (ADSI), Innsbruck, Austria
| | - Andrea Ballabio
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy. .,Medical Genetics Unit, Department of Medical and Translational Science, Federico II University, Naples, Italy. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA. .,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA. .,SSM School for Advanced Studies, Federico II University, Naples, Italy.
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239
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Yu J, Wu C, Wu Q, Huang J, Fu W, Xie X, Li W, Tang W, Xu C, Jin G. PCYT1A suppresses proliferation and migration via inhibiting mTORC1 pathway in lung adenocarcinoma. Biochem Biophys Res Commun 2020; 529:353-361. [PMID: 32703435 DOI: 10.1016/j.bbrc.2020.05.164] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 05/22/2020] [Indexed: 12/26/2022]
Abstract
Lung cancer is one of most common malignant cancer worldwide. It is emerging that PCYT1A, a rate-limiting enzyme required for the biosynthesis of phosphatidylcholine, is associated with cancer progression. However, the biological functions and underlying molecular mechanisms of PCYT1A in lung adenocarcinoma is still unknown. Here we found that PCYT1A suppressed lung adenocarcinoma cancer cell proliferation and migration. Mechanically, PCYT1A served as a novel negative regulator of mTORC1 signaling. PCYT1A knockdown enhanced the malignant proliferation and migration of lung adenocarcinoma cells by activating mTORC1. The promoting effects of PCYT1A silencing on cell proliferation and migration could be abolished when mTORC1 signaling was inhibited by rapamycin or RAPTOR depletion. Importantly, PCYT1A high expression predicted longer survival of lung cancer patients. The expression of PCYT1A was also negatively correlated with mTORC1 activation in the clinical lung cancer samples. We therefore reveal that PCYT1A suppresses proliferation and migration by inhibiting the mTORC1 signaling pathway in lung adenocarcinoma. PCYT1A shows as a potential promising biomarker in lung adenocarcinoma.
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Affiliation(s)
- Jing Yu
- Department of Oncology, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, China; Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), And Key Laboratory of Tumor Immunopathology, Ministry of Education of China, Chongqing, China
| | - Changtao Wu
- Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), And Key Laboratory of Tumor Immunopathology, Ministry of Education of China, Chongqing, China; Department of Colorectal and Anal Surgery, The First Affiliated Hospital, Guangxi Medical University, Nanning, 530021, China
| | - Qi Wu
- Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), And Key Laboratory of Tumor Immunopathology, Ministry of Education of China, Chongqing, China
| | - Jiafeng Huang
- Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), And Key Laboratory of Tumor Immunopathology, Ministry of Education of China, Chongqing, China
| | - Wenjuan Fu
- Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), And Key Laboratory of Tumor Immunopathology, Ministry of Education of China, Chongqing, China
| | - Xuemei Xie
- Department of Pathology, The Affiliated Hospital of North Sichuan Medical College, Nanchong, 637100, China
| | - Wen Li
- Integrative Cancer Center & Cancer Clinical Research Center, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine University of Electronic Science and Technology of China, Chengdu, 610047, China
| | - Weizhong Tang
- Department of Gastrointestinal Surgery, Affiliated Tumor Hospital of Guangxi Medical University, Nanning, 530021, China
| | - Chuan Xu
- Department of Oncology, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, China; Integrative Cancer Center & Cancer Clinical Research Center, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine University of Electronic Science and Technology of China, Chengdu, 610047, China.
| | - Guoxiang Jin
- Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University (Army Medical University), And Key Laboratory of Tumor Immunopathology, Ministry of Education of China, Chongqing, China.
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240
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Shin HR, Zoncu R. The Lysosome at the Intersection of Cellular Growth and Destruction. Dev Cell 2020; 54:226-238. [PMID: 32610045 DOI: 10.1016/j.devcel.2020.06.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/01/2020] [Indexed: 12/27/2022]
Abstract
The lysosome is an essential catabolic organelle that consumes cellular biomass to regenerate basic building blocks that can fuel anabolic reactions. This simple view has evolved more recently to integrate novel functions of the lysosome as a key signaling center, which can steer the metabolic trajectory of cells in response to changes in nutrients, growth factors, and stress. Master protein kinases and transcription factors mediate the growth-promoting and catabolic activities of the lysosome and undergo a complex interplay that enables cellular adaptation to ever-changing metabolic conditions. Understanding how this coordination occurs will shed light on the fundamental logic of how the lysosome functions to control growth in the context of development, tissue homeostasis, and cancer.
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Affiliation(s)
- Hijai R Shin
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA; The Paul F. Glenn Center for Aging Research at the University of California Berkeley, Berkeley, CA 94720, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA; The Paul F. Glenn Center for Aging Research at the University of California Berkeley, Berkeley, CA 94720, USA.
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241
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Hansmann P, Brückner A, Kiontke S, Berkenfeld B, Seebohm G, Brouillard P, Vikkula M, Jansen FE, Nellist M, Oeckinghaus A, Kümmel D. Structure of the TSC2 GAP Domain: Mechanistic Insight into Catalysis and Pathogenic Mutations. Structure 2020; 28:933-942.e4. [PMID: 32502382 DOI: 10.1016/j.str.2020.05.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 02/06/2020] [Accepted: 05/15/2020] [Indexed: 12/17/2022]
Abstract
The TSC complex is the cognate GTPase-activating protein (GAP) for the small GTPase Rheb and a crucial regulator of the mechanistic target of rapamycin complex 1 (mTORC1). Mutations in the TSC1 and TSC2 subunits of the complex cause tuberous sclerosis complex (TSC). We present the crystal structure of the catalytic asparagine-thumb GAP domain of TSC2. A model of the TSC2-Rheb complex and molecular dynamics simulations suggest that TSC2 Asn1643 and Rheb Tyr35 are key active site residues, while Rheb Arg15 and Asp65, previously proposed as catalytic residues, contribute to the TSC2-Rheb interface and indirectly aid catalysis. The TSC2 GAP domain is further stabilized by interactions with other TSC2 domains. We characterize TSC2 variants that partially affect TSC2 functionality and are associated with atypical symptoms in patients, suggesting that mutations in TSC1 and TSC2 might predispose to neurological and vascular disorders without fulfilling the clinical criteria for TSC.
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Affiliation(s)
- Patrick Hansmann
- Westfälische Wilhelms-Universität, Institute of Biochemistry, Wilhelm Klemm-Str. 2, 48149 Münster, Germany
| | - Anne Brückner
- Westfälische Wilhelms-Universität, Institute of Biochemistry, Wilhelm Klemm-Str. 2, 48149 Münster, Germany; Westfälische Wilhelms-Universität, Institute of Molecular Tumor Biology, Robert-Koch-Str. 43, 48149 Münster, Germany
| | - Stephan Kiontke
- Philipps-Universität Marburg, Faculty of Biology, Department of Plant Physiology and Photobiology, Karl-von-Frisch-Str. 8, 35032 Marburg, Germany
| | - Bianca Berkenfeld
- Westfälische Wilhelms-Universität, Institute of Biochemistry, Wilhelm Klemm-Str. 2, 48149 Münster, Germany
| | - Guiscard Seebohm
- University Hospital Münster, Institute for Genetics of Heart Diseases, Department of Cardiovascular Medicine, Robert-Koch-Str. 45, 48149 Münster, Germany
| | - Pascal Brouillard
- Université Catholique de Louvain, de Duve Institute, Human Molecular Genetics, Brussels, Belgium
| | - Miikka Vikkula
- Université Catholique de Louvain, de Duve Institute, Human Molecular Genetics, Brussels, Belgium; WELBIO (Walloon Excellence in Lifesciences and Biotechnology), de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Floor E Jansen
- Department of Child Neurology, Brain Center UMC Utrecht, Utrecht, the Netherlands
| | - Mark Nellist
- Department of Clinical Genetics, Erasmus Medical Center, Wytemaweg 80, 3015 CN Rotterdam, the Netherlands
| | - Andrea Oeckinghaus
- Westfälische Wilhelms-Universität, Institute of Molecular Tumor Biology, Robert-Koch-Str. 43, 48149 Münster, Germany
| | - Daniel Kümmel
- Westfälische Wilhelms-Universität, Institute of Biochemistry, Wilhelm Klemm-Str. 2, 48149 Münster, Germany.
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242
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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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243
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Chen R, Mao L, Shi R, Wang W, Cheng J. circRNA MYLK Accelerates Cervical Cancer via Up-Regulation of RHEB and Activation of mTOR Signaling. Cancer Manag Res 2020; 12:3611-3621. [PMID: 32547198 PMCID: PMC7245433 DOI: 10.2147/cmar.s238172] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/18/2020] [Indexed: 12/16/2022] Open
Abstract
Background Growing evidence directly suggested that circular RNAs (circRNAs) are crucial contributors in the course of cervical cancer (CC) onset and progression. Nevertheless, a large number of circRNAs have not been fully addressed in their function and underlying mechanisms during CC etiology. Purpose Our study focused on the function of circRNA MYLK (myosin light chain kinase), one novel tumor-related circRNA, in CC cell behaviors. Methods Firstly, we evaluated the expression profile of circMYLK in CC cells and in normal Ect1/E6E7 cell line. Moreover, the accurate function of circMYLK in CC cells was assessed via colony formation, CCK-8, EdU, and TUNEL assay. The association among circRNAs, miRNA, and target mRNAs was predicated by bioinformatics methods and validated in mechanical assays. Results We disclosed that circMYLK was up-regulated in CC cell lines and acted as a sponge of miR-1301-3p. Besides, downstream miR-1301-3p was capable of reversing circMYLK-mediated CC cell growth and apoptosis. Furthermore, we validated that circMYLK bound to miR-1301-3p as a sponge to upregulate RHEB (Ras homolog, mTORC1 binding) expression. As annotated in prior works, RHEB was responsible for mTOR signaling transduction. Therefore, we investigated whether circMYLK functioned its tumor-facilitating impact in CC through a RHEB-dependent mTOR signaling activation. Conclusion It was unveiled that circMYLK sponged miR-1301-3p to promote RHEB expression, which resulted in mTOR signaling activation and CC cell malignant growth.
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Affiliation(s)
- Rui Chen
- Department of Gynecology, East Hospital Affiliated to Tongji University, Shanghai 200012, People's Republic of China
| | - Luning Mao
- Department of Pathology, Basic Medical College, Fudan University, Shanghai 200032, People's Republic of China
| | - Rui Shi
- Department of Gynecology, East Hospital Affiliated to Tongji University, Shanghai 200012, People's Republic of China
| | - Wenjing Wang
- Department of Gynecology, East Hospital Affiliated to Tongji University, Shanghai 200012, People's Republic of China
| | - Jingxin Cheng
- Department of Gynecology, East Hospital Affiliated to Tongji University, Shanghai 200012, People's Republic of China
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244
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Ogasawara R, Jensen TE, Goodman CA, Hornberger TA. Resistance Exercise-Induced Hypertrophy: A Potential Role for Rapamycin-Insensitive mTOR. Exerc Sport Sci Rev 2020; 47:188-194. [PMID: 30870215 DOI: 10.1249/jes.0000000000000189] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The mechanistic target of rapamycin (mTOR) exerts both rapamycin-sensitive and rapamycin-insensitive signaling events, and the rapamycin-sensitive components of mTOR signaling have been widely implicated in the pathway through which resistance exercise induces skeletal muscle hypertrophy. This review explores the hypothesis that rapamycin-insensitive components of mTOR signaling also contribute to this highly important process.
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Affiliation(s)
- Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan.,Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | - Thomas E Jensen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | - Craig A Goodman
- Institute of Health and Sport, Victoria University, Melbourne.,Australian Institute for Musculoskeletal Science, Victoria University, St. Albans, Victoria, Australia
| | - Troy A Hornberger
- Department of Comparative Biosciences, and.,School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI
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245
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Riggi M, Kusmider B, Loewith R. The flipside of the TOR coin - TORC2 and plasma membrane homeostasis at a glance. J Cell Sci 2020; 133:133/9/jcs242040. [PMID: 32393676 DOI: 10.1242/jcs.242040] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Target of rapamycin (TOR) is a serine/threonine protein kinase conserved in most eukaryote organisms. TOR assembles into two multiprotein complexes (TORC1 and TORC2), which function as regulators of cellular growth and homeostasis by serving as direct transducers of extracellular biotic and abiotic signals, and, through their participation in intrinsic feedback loops, respectively. TORC1, the better-studied complex, is mainly involved in cell volume homeostasis through regulating accumulation of proteins and other macromolecules, while the functions of the lesser-studied TORC2 are only now starting to emerge. In this Cell Science at a Glance article and accompanying poster, we aim to highlight recent advances in our understanding of TORC2 signalling, particularly those derived from studies in yeast wherein TORC2 has emerged as a major regulator of cell surface homeostasis.
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Affiliation(s)
- Margot Riggi
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland.,Department of Biochemistry, University of Geneva, Geneva, Switzerland.,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Beata Kusmider
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland.,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Robbie Loewith
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland .,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
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246
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Zhu M, Wang XQ. Regulation of mTORC1 by Small GTPases in Response to Nutrients. J Nutr 2020; 150:1004-1011. [PMID: 31965176 DOI: 10.1093/jn/nxz301] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 10/07/2019] [Accepted: 11/18/2019] [Indexed: 12/15/2022] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a highly evolutionarily conserved serine/threonine kinase that regulates cell growth and metabolism in response to multiple environmental cues, such as nutrients, hormones, energy, and stress. Deregulation of mTORC1 can lead to diseases such as diabetes, obesity, and cancer. A series of small GTPases, including Rag, Ras homolog enriched in brain (Rheb), adenosine diphosphate ribosylation factor 1 (Arf1), Ras-related protein Ral-A, Ras homolog (Rho), and Rab, are involved in regulating mTORC1 in response to nutrients, and mTORC1 is differentially regulated via these small GTPases according to specific conditions. Leucine and arginine sensing are considered to be well-confirmed amino acid-sensing signals, activating mTORC1 via a Rag GTPase-dependent mechanism as well as the Ragulator complex and vacuolar H+-adenosine triphosphatase (v-ATPase). Glutamine promotes mTORC1 activation via Arf1 independently of the Rag GTPase. In this review, we summarize current knowledge regarding the regulation of mTORC1 activity by small GTPases in response to nutrients, focusing on the function of small GTPases in mTORC1 activation and how small GTPases are regulated by nutrients.
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Affiliation(s)
- Min Zhu
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong, China
| | - Xiu-Qi Wang
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong, China
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247
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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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248
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Mutvei AP, Nagiec MJ, Hamann JC, Kim SG, Vincent CT, Blenis J. Rap1-GTPases control mTORC1 activity by coordinating lysosome organization with amino acid availability. Nat Commun 2020; 11:1416. [PMID: 32184389 PMCID: PMC7078236 DOI: 10.1038/s41467-020-15156-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 02/17/2020] [Indexed: 02/08/2023] Open
Abstract
The kinase mTOR complex 1 (mTORC1) promotes cellular growth and is frequently dysregulated in cancers. In response to nutrients, mTORC1 is activated on lysosomes by Rag and Rheb guanosine triphosphatases (GTPases) and drives biosynthetic processes. How limitations in nutrients suppress mTORC1 activity remains poorly understood. We find that when amino acids are limited, the Rap1-GTPases confine lysosomes to the perinuclear region and reduce lysosome abundance, which suppresses mTORC1 signaling. Rap1 activation, which is independent of known amino acid signaling factors, limits the lysosomal surface available for mTORC1 activation. Conversely, Rap1 depletion expands the lysosome population, which markedly increases association between mTORC1 and its lysosome-borne activators, leading to mTORC1 hyperactivity. Taken together, we establish Rap1 as a critical coordinator of the lysosomal system, and propose that aberrant changes in lysosomal surface availability can impact mTORC1 signaling output.
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Affiliation(s)
- Anders P Mutvei
- Weill Cornell Medicine, Sandra and Edward Meyer Cancer Center, Belfer Research Building, 413 E. 69th St., New York, NY, 10021, USA.
- Karolinska Institutet, Department of Microbiology, Tumor and Cell biology, Nobels väg 16, KI Solna Campus Karolinska Institutet, Box 280, SE-171 77, Stockholm, Sweden.
- Department of Immunology, Genetics and Pathology, Uppsala University, Rudbeck Laboratory, 751 85, Uppsala, Sweden.
| | - Michal J Nagiec
- Weill Cornell Medicine, Sandra and Edward Meyer Cancer Center, Belfer Research Building, 413 E. 69th St., New York, NY, 10021, USA
| | - Jens C Hamann
- Weill Cornell Medicine, Sandra and Edward Meyer Cancer Center, Belfer Research Building, 413 E. 69th St., New York, NY, 10021, USA
| | - Sang Gyun Kim
- Weill Cornell Medicine, Sandra and Edward Meyer Cancer Center, Belfer Research Building, 413 E. 69th St., New York, NY, 10021, USA
| | - C Theresa Vincent
- Department of Immunology, Genetics and Pathology, Uppsala University, Rudbeck Laboratory, 751 85, Uppsala, Sweden
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - John Blenis
- Weill Cornell Medicine, Sandra and Edward Meyer Cancer Center, Belfer Research Building, 413 E. 69th St., New York, NY, 10021, USA.
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249
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González A, Hall MN, Lin SC, Hardie DG. AMPK and TOR: The Yin and Yang of Cellular Nutrient Sensing and Growth Control. Cell Metab 2020; 31:472-492. [PMID: 32130880 DOI: 10.1016/j.cmet.2020.01.015] [Citation(s) in RCA: 385] [Impact Index Per Article: 96.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The AMPK (AMP-activated protein kinase) and TOR (target-of-rapamycin) pathways are interlinked, opposing signaling pathways involved in sensing availability of nutrients and energy and regulation of cell growth. AMPK (Yin, or the "dark side") is switched on by lack of energy or nutrients and inhibits cell growth, while TOR (Yang, or the "bright side") is switched on by nutrient availability and promotes cell growth. Genes encoding the AMPK and TOR complexes are found in almost all eukaryotes, suggesting that these pathways arose very early during eukaryotic evolution. During the development of multicellularity, an additional tier of cell-extrinsic growth control arose that is mediated by growth factors, but these often act by modulating nutrient uptake so that AMPK and TOR remain the underlying regulators of cellular growth control. In this review, we discuss the evolution, structure, and regulation of the AMPK and TOR pathways and the complex mechanisms by which they interact.
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Affiliation(s)
- Asier González
- Biozentrum, University of Basel, CH4056 Basel, Switzerland
| | - Michael N Hall
- Biozentrum, University of Basel, CH4056 Basel, Switzerland
| | - Sheng-Cai Lin
- School of Life Sciences, Xiamen University, Xiamen, 361102 Fujian, China
| | - D Grahame Hardie
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK.
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de Martín Garrido N, Aylett CHS. Nutrient Signaling and Lysosome Positioning Crosstalk Through a Multifunctional Protein, Folliculin. Front Cell Dev Biol 2020; 8:108. [PMID: 32195250 PMCID: PMC7063858 DOI: 10.3389/fcell.2020.00108] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 02/10/2020] [Indexed: 12/16/2022] Open
Abstract
FLCN was identified as the gene responsible for Birt-Hogg-Dubé (BHD) syndrome, a hereditary syndrome associated with the appearance of familiar renal oncocytomas. Most mutations affecting FLCN result in the truncation of the protein, and therefore loss of its associated functions, as typical for a tumor suppressor. FLCN encodes the protein folliculin (FLCN), which is involved in numerous biological processes; mutations affecting this protein thus lead to different phenotypes depending on the cellular context. FLCN forms complexes with two large interacting proteins, FNIP1 and FNIP2. Structural studies have shown that both FLCN and FNIPs contain longin and differentially expressed in normal versus neoplastic cells (DENN) domains, typically involved in the regulation of small GTPases. Accordingly, functional studies show that FLCN regulates both the Rag and the Rab GTPases depending on nutrient availability, which are respectively involved in the mTORC1 pathway and lysosomal positioning. Although recent structural studies shed light on the precise mechanism by which FLCN regulates the Rag GTPases, which in turn regulate mTORC1, how FLCN regulates membrane trafficking through the Rab GTPases or the significance of the intriguing FLCN-FNIP-AMPK complex formation are questions that still remain unanswered. We discuss the recent progress in our understanding of FLCN regulation of both growth signaling and lysosomal positioning, as well as future approaches to establish detailed mechanisms to explain the disparate phenotypes caused by the loss of FLCN function and the development of BHD-associated and other tumors.
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Affiliation(s)
| | - Christopher H. S. Aylett
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
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