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Leclerc NR, Dunne TM, Shrestha S, Johnson CP, Kelley JB. TOR signaling regulates GPCR levels on the plasma membrane and suppresses the Saccharomyces cerevisiae mating pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.09.593412. [PMID: 38798445 PMCID: PMC11118302 DOI: 10.1101/2024.05.09.593412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Saccharomyces cerevisiae respond to mating pheromone through the GPCRs Ste2 and Ste3, which promote growth of a mating projection in response to ligand binding. This commitment to mating is nutritionally and energetically taxing, and so we hypothesized that the cell may suppress mating signaling during starvation. We set out to investigate negative regulators of the mating pathway in nutritionally depleted environments. Here, we report that nutrient deprivation led to loss of Ste2 from the plasma membrane. Recapitulating this effect with nitrogen starvation led us to hypothesize that it was due to TORC1 signaling. Rapamycin inhibition of TORC1 impacted membrane levels of all yeast GPCRs. Inhibition of TORC1 also dampened mating pathway output. Deletion analysis revealed that TORC1 repression leads to α-arrestin-directed CME through TORC2-Ypk1 signaling. We then set out to determine whether major downstream effectors of the TOR complexes also downregulate pathway output during mating. We found that autophagy contributes to pathway downregulation through analysis of strains lacking ATG8 . We also show that Ypk1 significantly reduced pathway output. Thus, both autophagy machinery and TORC2-Ypk1 signaling serve as attenuators of pheromone signaling during mating. Altogether, we demonstrate that the stress-responsive TOR complexes coordinate GPCR endocytosis and reduce the magnitude of pheromone signaling, in ligand-independent and ligand-dependent contexts. One Sentence Summary TOR signaling regulates the localization of all Saccharomyces cerevisiae GPCRs during starvation and suppress the mating pathway in the presence and absence of ligand.
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2
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Liu Y, Zhang M, Jang H, Nussinov R. The allosteric mechanism of mTOR activation can inform bitopic inhibitor optimization. Chem Sci 2024; 15:1003-1017. [PMID: 38239681 PMCID: PMC10793652 DOI: 10.1039/d3sc04690g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 12/06/2023] [Indexed: 01/22/2024] Open
Abstract
mTOR serine/threonine kinase is a cornerstone in the PI3K/AKT/mTOR pathway. Yet, the detailed mechanism of activation of its catalytic core is still unresolved, likely due to mTOR complexes' complexity. Its dysregulation was implicated in cancer and neurodevelopmental disorders. Using extensive molecular dynamics (MD) simulations and compiled published experimental data, we determine exactly how mTOR's inherent motifs can control the conformational changes in the kinase domain, thus kinase activity. We also chronicle the critical regulation by the unstructured negative regulator domain (NRD). When positioned inside the catalytic cleft (NRD IN state), mTOR tends to adopt a deep and closed catalytic cleft. This is primarily due to the direct interaction with the FKBP-rapamycin binding (FRB) domain which restricts it, preventing substrate access. Conversely, when outside the catalytic cleft (NRD OUT state), mTOR favors an open conformation, exposing the substrate-binding site on the FRB domain. We further show how an oncogenic mutation (L2427R) promotes shifting the mTOR ensemble toward the catalysis-favored state. Collectively, we extend mTOR's "active-site restriction" mechanism and clarify mutation action. In particular, our mechanism suggests that RMC-5552 (RMC-6272) bitopic inhibitors may benefit from adjustment of the (PEG8) linker length when targeting certain mTOR variants. In the cryo-EM mTOR/RMC-5552 structure, the distance between the allosteric and orthosteric inhibitors is ∼22.7 Å. With a closed catalytic cleft, this linker bridges the sites. However, in our activation mechanism, in the open cleft it expands to ∼24.7 Å, offering what we believe to be the first direct example of how discovering an activation mechanism can potentially increase the affinity of inhibitors targeting mutants.
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Affiliation(s)
- Yonglan Liu
- Cancer Innovation Laboratory, National Cancer Institute Frederick MD 21702 USA
| | - Mingzhen Zhang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research Frederick MD 21702 USA +1-301-846-5579
| | - Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research Frederick MD 21702 USA +1-301-846-5579
| | - Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research Frederick MD 21702 USA +1-301-846-5579
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University Tel Aviv 69978 Israel
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3
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Goul C, Peruzzo R, Zoncu R. The molecular basis of nutrient sensing and signalling by mTORC1 in metabolism regulation and disease. Nat Rev Mol Cell Biol 2023; 24:857-875. [PMID: 37612414 DOI: 10.1038/s41580-023-00641-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2023] [Indexed: 08/25/2023]
Abstract
The Ser/Thr kinase mechanistic target of rapamycin (mTOR) is a central regulator of cellular metabolism. As part of mTOR complex 1 (mTORC1), mTOR integrates signals such as the levels of nutrients, growth factors, energy sources and oxygen, and triggers responses that either boost anabolism or suppress catabolism. mTORC1 signalling has wide-ranging consequences for the growth and homeostasis of key tissues and organs, and its dysregulated activity promotes cancer, type 2 diabetes, neurodegeneration and other age-related disorders. How mTORC1 integrates numerous upstream cues and translates them into specific downstream responses is an outstanding question with major implications for our understanding of physiology and disease mechanisms. In this Review, we discuss recent structural and functional insights into the molecular architecture of mTORC1 and its lysosomal partners, which have greatly increased our mechanistic understanding of nutrient-dependent mTORC1 regulation. We also discuss the emerging involvement of aberrant nutrient-mTORC1 signalling in multiple diseases.
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Affiliation(s)
- Claire Goul
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Roberta Peruzzo
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
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4
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Jakobson CM, Aguilar-Rodríguez J, Jarosz DF. Hsp90 shapes adaptation by controlling the fitness consequences of regulatory variation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.30.564848. [PMID: 37961536 PMCID: PMC10634948 DOI: 10.1101/2023.10.30.564848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The essential stress-responsive chaperone Hsp90 impacts development and adaptation from microbes to humans. Yet despite evidence of its role in evolution, pathogenesis, and oncogenic transformation, the molecular mechanisms by which Hsp90 alters the consequences of mutations remain vigorously debated. Here we exploit the power of nucleotide-resolution genetic mapping in Saccharomyces cerevisiae to uncover more than 1,000 natural variant-to-phenotype associations governed by this molecular chaperone. Strikingly, Hsp90 more frequently modified the phenotypic effects of cis-regulatory variation than variants that altered protein sequence. Moreover, these interactions made the largest contribution to Hsp90-dependent heredity. Nearly all interacting variants-both regulatory and protein-coding-fell within clients of Hsp90 or targets of its direct binding partners. Hsp90 activity affected mutations in evolutionarily young genes, segmental deletions, and heterozygotes, highlighting its influence on variation central to evolutionary novelty. Reconciling the diverse epistatic effects of this chaperone, synthetic transcriptional regulation and reconstructions of natural alleles by genome editing revealed a central role for Hsp90 in regulating the fundamental relationship between activity and phenotype. Our findings establish that non-coding variation is a core driver of Hsp90's influence on heredity, offering a mechanistic explanation for the chaperone's strong effects on evolution and development across species.
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Affiliation(s)
- Christopher M. Jakobson
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
- These authors contributed equally
| | - José Aguilar-Rodríguez
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Biology, Stanford University, Stanford, CA, USA
- These authors contributed equally
| | - Daniel F. Jarosz
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
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5
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Rivas VN, Kaplan JL, Kennedy SA, Fitzgerald S, Crofton AE, Farrell A, Grubb L, Jauregui CE, Grigorean G, Choi E, Harris SP, Stern JA. Multi-Omic, Histopathologic, and Clinicopathologic Effects of Once-Weekly Oral Rapamycin in a Naturally Occurring Feline Model of Hypertrophic Cardiomyopathy: A Pilot Study. Animals (Basel) 2023; 13:3184. [PMID: 37893908 PMCID: PMC10603660 DOI: 10.3390/ani13203184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 10/09/2023] [Accepted: 10/10/2023] [Indexed: 10/29/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) remains the single most common cardiomyopathy in cats, with a staggering prevalence as high as 15%. To date, little to no direct therapeutical intervention for HCM exists for veterinary patients. A previous study aimed to evaluate the effects of delayed-release (DR) rapamycin dosing in a client-owned population of subclinical, non-obstructive, HCM-affected cats and reported that the drug was well tolerated and resulted in beneficial LV remodeling. However, the precise effects of rapamycin in the hypertrophied myocardium remain unknown. Using a feline research colony with naturally occurring hereditary HCM (n = 9), we embarked on the first-ever pilot study to examine the tissue-, urine-, and plasma-level proteomic and tissue-level transcriptomic effects of an intermittent low dose (0.15 mg/kg) and high dose (0.30 mg/kg) of DR oral rapamycin once weekly. Rapamycin remained safe and well tolerated in cats receiving both doses for eight weeks. Following repeated weekly dosing, transcriptomic differences between the low- and high-dose groups support dose-responsive suppressive effects on myocardial hypertrophy and stimulatory effects on autophagy. Differences in the myocardial proteome between treated and control cats suggest potential anti-coagulant/-thrombotic, cellular remodeling, and metabolic effects of the drug. The results of this study closely recapitulate what is observed in the human literature, and the use of rapamycin in the clinical setting as the first therapeutic agent with disease-modifying effects on HCM remains promising. The results of this study establish the need for future validation efforts that investigate the fine-scale relationship between rapamycin treatment and the most compelling gene expression and protein abundance differences reported here.
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Affiliation(s)
- Victor N. Rivas
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
| | - Joanna L. Kaplan
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | | | | | - Amanda E. Crofton
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | | | | | - Carina E. Jauregui
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
| | - Gabriela Grigorean
- Proteomics Core Facility, University of California-Davis, Davis, CA 95616, USA
| | - Eunju Choi
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA;
| | - Samantha P. Harris
- Department of Physiology, College of Medicine-Tucson, University of Arizona, Tucson, AZ 85724, USA
| | - Joshua A. Stern
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA
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6
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Linde-Garelli KY, Rogala KB. Structural mechanisms of the mTOR pathway. Curr Opin Struct Biol 2023; 82:102663. [PMID: 37572585 DOI: 10.1016/j.sbi.2023.102663] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 07/01/2023] [Accepted: 07/07/2023] [Indexed: 08/14/2023]
Abstract
The mTOR signaling pathway is essential for regulating cell growth and mammalian metabolism. The mTOR kinase forms two complexes, mTORC1 and mTORC2, which respond to external stimuli and regulate differential downstream targets. Cellular membrane-associated translocation mediates function and assembly of the mTOR complexes, and recent structural studies have begun uncovering the molecular basis by which the mTOR pathway (1) regulates signaling inputs, (2) recruits substrates, (3) localizes to biological membranes, and (4) becomes activated. Moreover, indications of dysregulated mTOR signaling are implicated in a wide range of diseases and an increasingly comprehensive understanding of structural mechanisms is driving novel translational development.
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Affiliation(s)
- Karen Y Linde-Garelli
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA; Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Kacper B Rogala
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA; Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA.
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7
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Fallone L, Walzer T, Marçais A. Signaling Pathways Leading to mTOR Activation Downstream Cytokine Receptors in Lymphocytes in Health and Disease. Int J Mol Sci 2023; 24:12736. [PMID: 37628917 PMCID: PMC10454121 DOI: 10.3390/ijms241612736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/09/2023] [Accepted: 08/10/2023] [Indexed: 08/27/2023] Open
Abstract
CD8+ T cells and Natural Killer (NK) cells are cytotoxic lymphocytes important in the response to intracellular pathogens and cancer. Their activity depends on the integration of a large set of intracellular and environmental cues, including antigenic signals, cytokine stimulation and nutrient availability. This integration is achieved by signaling hubs, such as the mechanistic target of rapamycin (mTOR). mTOR is a conserved protein kinase that controls cellular growth and metabolism in eukaryotic cells and, therefore, is essential for lymphocyte development and maturation. However, our current understanding of mTOR signaling comes mostly from studies performed in transformed cell lines, which constitute a poor model for comprehending metabolic pathway regulation. Therefore, it is only quite recently that the regulation of mTOR in primary cells has been assessed. Here, we review the signaling pathways leading to mTOR activation in CD8+ T and NK cells, focusing on activation by cytokines. We also discuss how this knowledge can contribute to immunotherapy development, particularly for cancer treatment.
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Affiliation(s)
| | | | - Antoine Marçais
- CIRI—Centre International de Recherche en Infectiologie (Team Lyacts), Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, F-69007 Lyon, France; (L.F.); (T.W.)
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8
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Mannick JB, Lamming DW. Targeting the biology of aging with mTOR inhibitors. NATURE AGING 2023; 3:642-660. [PMID: 37142830 PMCID: PMC10330278 DOI: 10.1038/s43587-023-00416-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 04/07/2023] [Indexed: 05/06/2023]
Abstract
Inhibition of the protein kinase mechanistic target of rapamycin (mTOR) with the Food and Drug Administration (FDA)-approved therapeutic rapamycin promotes health and longevity in diverse model organisms. More recently, specific inhibition of mTORC1 to treat aging-related conditions has become the goal of basic and translational scientists, clinicians and biotechnology companies. Here, we review the effects of rapamycin on the longevity and survival of both wild-type mice and mouse models of human diseases. We discuss recent clinical trials that have explored whether existing mTOR inhibitors can safely prevent, delay or treat multiple diseases of aging. Finally, we discuss how new molecules may provide routes to the safer and more selective inhibition of mTOR complex 1 (mTORC1) in the decade ahead. We conclude by discussing what work remains to be done and the questions that will need to be addressed to make mTOR inhibitors part of the standard of care for diseases of aging.
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Affiliation(s)
| | - Dudley W Lamming
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA.
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9
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Sarkar N, Singh A, Kumar P, Kaushik M. Protein kinases: Role of their dysregulation in carcinogenesis, identification and inhibition. Drug Res (Stuttg) 2023; 73:189-199. [PMID: 36822216 DOI: 10.1055/a-1989-1856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Protein kinases belong to the phosphor-transferases superfamily of enzymes, which "activate" enzymes via phosphorylation. The kinome of an organism is the total set of genes in the genome, which encode for all the protein kinases. Certain mutations in the kinome have been linked to dysregulation of protein kinases, which in turn can lead to several diseases and disorders including cancer. In this review, we have briefly discussed the role of protein kinases in various biochemical processes by categorizing cancer associated phenotypes and giving their protein kinase examples. Various techniques have also been discussed, which are being used to analyze the structure of protein kinases, and associate their roles in the oncogenesis. We have also discussed protein kinase inhibitors and United States Federal Drug Administration (USFDA) approved drugs, which target protein kinases and can serve as a counter to protein kinase dysregulation and mitigate the effects of oncogenesis. Overall, this review briefs about the importance of protein kinases, their roles in oncogenesis on dysregulation and how their inhibition via various drugs can be used to mitigate their effects.
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Affiliation(s)
- Niloy Sarkar
- Nano-Bioconjugate Chemistry Lab, Cluster Innovation Centre, University of Delhi, Delhi, India.,Department of Environmental Studies, University of Delhi, Delhi, India
| | - Amit Singh
- Nano-Bioconjugate Chemistry Lab, Cluster Innovation Centre, University of Delhi, Delhi, India.,Department of Chemistry, University of Delhi, Delhi, India
| | - Pankaj Kumar
- Nano-Bioconjugate Chemistry Lab, Cluster Innovation Centre, University of Delhi, Delhi, India.,Department of Chemistry, University of Delhi, Delhi, India
| | - Mahima Kaushik
- Nano-Bioconjugate Chemistry Lab, Cluster Innovation Centre, University of Delhi, Delhi, India
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10
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Huynh C, Ryu J, Lee J, Inoki A, Inoki K. Nutrient-sensing mTORC1 and AMPK pathways in chronic kidney diseases. Nat Rev Nephrol 2023; 19:102-122. [PMID: 36434160 DOI: 10.1038/s41581-022-00648-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2022] [Indexed: 11/27/2022]
Abstract
Nutrients such as glucose, amino acids and lipids are fundamental sources for the maintenance of essential cellular processes and homeostasis in all organisms. The nutrient-sensing kinases mechanistic target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) are expressed in many cell types and have key roles in the control of cell growth, proliferation, differentiation, metabolism and survival, ultimately contributing to the physiological development and functions of various organs, including the kidney. Dysregulation of these kinases leads to many human health problems, including cancer, neurodegenerative diseases, metabolic disorders and kidney diseases. In the kidney, physiological levels of mTOR and AMPK activity are required to support kidney cell growth and differentiation and to maintain kidney cell integrity and normal nephron function, including transport of electrolytes, water and glucose. mTOR forms two functional multi-protein kinase complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Hyperactivation of mTORC1 leads to podocyte and tubular cell dysfunction and vulnerability to injury, thereby contributing to the development of chronic kidney diseases, including diabetic kidney disease, obesity-related kidney disease and polycystic kidney disease. Emerging evidence suggests that targeting mTOR and/or AMPK could be an effective therapeutic approach to controlling or preventing these diseases.
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Affiliation(s)
- Christopher Huynh
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA.,Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Jaewhee Ryu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Jooho Lee
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Ayaka Inoki
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA.,Department of Internal Medicine, Division of Nephrology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Ken Inoki
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA. .,Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA. .,Department of Internal Medicine, Division of Nephrology, University of Michigan Medical School, Ann Arbor, MI, USA.
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11
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TOR complex 2 is a master regulator of plasma membrane homeostasis. Biochem J 2022; 479:1917-1940. [PMID: 36149412 PMCID: PMC9555796 DOI: 10.1042/bcj20220388] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/17/2022]
Abstract
As first demonstrated in budding yeast (Saccharomyces cerevisiae), all eukaryotic cells contain two, distinct multi-component protein kinase complexes that each harbor the TOR (Target Of Rapamycin) polypeptide as the catalytic subunit. These ensembles, dubbed TORC1 and TORC2, function as universal, centrally important sensors, integrators, and controllers of eukaryotic cell growth and homeostasis. TORC1, activated on the cytosolic surface of the lysosome (or, in yeast, on the cytosolic surface of the vacuole), has emerged as a primary nutrient sensor that promotes cellular biosynthesis and suppresses autophagy. TORC2, located primarily at the plasma membrane, plays a major role in maintaining the proper levels and bilayer distribution of all plasma membrane components (sphingolipids, glycerophospholipids, sterols, and integral membrane proteins). This article surveys what we have learned about signaling via the TORC2 complex, largely through studies conducted in S. cerevisiae. In this yeast, conditions that challenge plasma membrane integrity can, depending on the nature of the stress, stimulate or inhibit TORC2, resulting in, respectively, up-regulation or down-regulation of the phosphorylation and thus the activity of its essential downstream effector the AGC family protein kinase Ypk1. Through the ensuing effect on the efficiency with which Ypk1 phosphorylates multiple substrates that control diverse processes, membrane homeostasis is maintained. Thus, the major focus here is on TORC2, Ypk1, and the multifarious targets of Ypk1 and how the functions of these substrates are regulated by their Ypk1-mediated phosphorylation, with emphasis on recent advances in our understanding of these processes.
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12
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Zhang Z, Fan Q, Luo X, Lou K, Weiss WA, Shokat KM. Brain-restricted mTOR inhibition with binary pharmacology. Nature 2022; 609:822-828. [PMID: 36104566 PMCID: PMC9492542 DOI: 10.1038/s41586-022-05213-y] [Citation(s) in RCA: 24] [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: 10/13/2020] [Accepted: 08/09/2022] [Indexed: 12/15/2022]
Abstract
On-target-off-tissue drug engagement is an important source of adverse effects that constrains the therapeutic window of drug candidates1,2. In diseases of the central nervous system, drugs with brain-restricted pharmacology are highly desirable. Here we report a strategy to achieve inhibition of mammalian target of rapamycin (mTOR) while sparing mTOR activity elsewhere through the use of the brain-permeable mTOR inhibitor RapaLink-1 and the brain-impermeable FKBP12 ligand RapaBlock. We show that this drug combination mitigates the systemic effects of mTOR inhibitors but retains the efficacy of RapaLink-1 in glioblastoma xenografts. We further present a general method to design cell-permeable, FKBP12-dependent kinase inhibitors from known drug scaffolds. These inhibitors are sensitive to deactivation by RapaBlock, enabling the brain-restricted inhibition of their respective kinase targets.
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Affiliation(s)
- Ziyang Zhang
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, CA, USA
| | - Qiwen Fan
- Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, USA
- Department of Neurology, University of California, San Francisco, CA, USA
| | - Xujun Luo
- Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, USA
- Department of Neurology, University of California, San Francisco, CA, USA
| | - Kevin Lou
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, CA, USA
| | - William A Weiss
- Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, USA
- Department of Neurology, University of California, San Francisco, CA, USA
- Department of Pediatrics, University of California, San Francisco, CA, USA
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
| | - Kevan M Shokat
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, CA, USA.
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13
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mTOR substrate phosphorylation in growth control. Cell 2022; 185:1814-1836. [PMID: 35580586 DOI: 10.1016/j.cell.2022.04.013] [Citation(s) in RCA: 117] [Impact Index Per Article: 58.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/05/2022] [Accepted: 04/07/2022] [Indexed: 12/20/2022]
Abstract
The target of rapamycin (TOR), discovered 30 years ago, is a highly conserved serine/threonine protein kinase that plays a central role in regulating cell growth and metabolism. It is activated by nutrients, growth factors, and cellular energy. TOR forms two structurally and functionally distinct complexes, TORC1 and TORC2. TOR signaling activates cell growth, defined as an increase in biomass, by stimulating anabolic metabolism while inhibiting catabolic processes. With emphasis on mammalian TOR (mTOR), we comprehensively reviewed the literature and identified all reported direct substrates. In the context of recent structural information, we discuss how mTORC1 and mTORC2, despite having a common catalytic subunit, phosphorylate distinct substrates. We conclude that the two complexes recruit different substrates to phosphorylate a common, minimal motif.
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14
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Simcox J, Lamming DW. The central moTOR of metabolism. Dev Cell 2022; 57:691-706. [PMID: 35316619 PMCID: PMC9004513 DOI: 10.1016/j.devcel.2022.02.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/20/2022] [Accepted: 02/24/2022] [Indexed: 12/21/2022]
Abstract
The protein kinase mechanistic target of rapamycin (mTOR) functions as a central regulator of metabolism, integrating diverse nutritional and hormonal cues to control anabolic processes, organismal physiology, and even aging. This review discusses the current state of knowledge regarding the regulation of mTOR signaling and the metabolic regulation of the four macromolecular building blocks of the cell: carbohydrate, nucleic acid, lipid, and protein by mTOR. We review the role of mTOR in the control of organismal physiology and aging through its action in key tissues and discuss the potential for clinical translation of mTOR inhibition for the treatment and prevention of diseases of aging.
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Affiliation(s)
- Judith Simcox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
| | - Dudley W Lamming
- William S. Middleton Memorial Veterans Hospital, Madison, WI, USA; Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA.
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15
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Tsverov J, Yegorov K, Powers T. Identification of defined structural elements within TOR2 kinase required for TOR Complex 2 assembly and function in S. cerevisiae. Mol Biol Cell 2022; 33:ar44. [PMID: 35293776 PMCID: PMC9282017 DOI: 10.1091/mbc.e21-12-0611] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
mTOR is a large protein kinase that assembles into two multi-subunit protein complexes, mTORC1 and mTORC2, to regulate cell growth in eukaryotic cells. While significant progress has been made in our understanding of the composition and structure of these complexes, important questions remain regarding the role of specific sequences within mTOR important for complex formation and activity. To address these issues, we have used a molecular genetic approach to explore TOR Complex assembly in budding yeast, where two closely related TOR paralogs, TOR1 and TOR2, partition preferentially into TORC1 versus TORC2, respectively. We previously identified a ∼500 amino acid segment within the N-terminal half of each protein, termed the Major Assembly Specificity (MAS) Domain, which can govern specificity in formation of each complex. In this study, we have extended the use of chimeric TOR1-TOR2 genes as a "sensitized" genetic system to identify specific subdomains rendered essential for TORC2 function, using synthetic lethal interaction analyses. Our findings reveal important design principles underlying the dimeric assembly of TORC2, as well as identify specific segments within the MAS domain critical for TORC2 function, to a level approaching single amino acid resolution. Together these findings highlight the complex and cooperative nature of TOR Complex assembly and function.
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Affiliation(s)
- Jennifer Tsverov
- Department of Molecular and Cellular Biology, College of Biological Sciences, UC Davis
| | - Kristina Yegorov
- Department of Molecular and Cellular Biology, College of Biological Sciences, UC Davis
| | - Ted Powers
- Department of Molecular and Cellular Biology, College of Biological Sciences, UC Davis
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16
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Li L, Zhu T, Song Y, Luo X, Datla R, Ren M. Target of rapamycin controls hyphal growth and pathogenicity through FoTIP4 in Fusarium oxysporum. MOLECULAR PLANT PATHOLOGY 2021; 22:1239-1255. [PMID: 34288333 PMCID: PMC8435236 DOI: 10.1111/mpp.13108] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/21/2021] [Accepted: 06/22/2021] [Indexed: 05/07/2023]
Abstract
Fusarium oxysporum is the causal agent of the devastating Fusarium wilt by invading and colonizing the vascular system in various plants, resulting in substantial economic losses worldwide. Target of rapamycin (TOR) is a central regulator that controls intracellular metabolism, cell growth, and stress responses in eukaryotes, but little is known about TOR signalling in F. oxysporum. In this study, we identified conserved FoTOR signalling pathway components including FoTORC1 and FoTORC2. Pharmacological assays showed that F. oxysporum is hypersensitive to rapamycin in the presence of FoFKBP12 while the deletion mutant strain ΔFofkbp12 is insensitive to rapamycin. Transcriptomic data indicated that FoTOR signalling controls multiple metabolic processes including ribosome biogenesis and cell wall-degrading enzymes (CWDEs). Genetic analysis revealed that FoTOR1 interacting protein 4 (FoTIP4) acts as a new component of FoTOR signalling to regulate hyphal growth and pathogenicity of F. oxysporum. Importantly, transcript levels of genes associated with ribosome biogenesis and CWDEs were dramatically downregulated in the ΔFotip4 mutant strain. Electrophoretic mobility shift assays showed that FoTIP4 can bind to the promoters of ribosome biogenesis- and CWDE-related genes to positively regulate the expression of these genes. These results suggest that FoTOR signalling plays central roles in regulating hyphal growth and pathogenicity of F. oxysporum and provide new insights into FoTOR1 as a target for controlling and preventing Fusarium wilt in plants.
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Affiliation(s)
- Linxuan Li
- Institute of Urban AgricultureChinese Academy of Agricultural SciencesChengdu National Agricultural Science and Technology CenterChengduChina
| | - Tingting Zhu
- Institute of Urban AgricultureChinese Academy of Agricultural SciencesChengdu National Agricultural Science and Technology CenterChengduChina
| | - Yun Song
- Zhengzhou Research BaseState Key Laboratory of Cotton BiologyZhengzhou UniversityZhengzhouChina
- School of Life SciencesLiaocheng UniversityLiaochengChina
| | - Xiumei Luo
- Institute of Urban AgricultureChinese Academy of Agricultural SciencesChengdu National Agricultural Science and Technology CenterChengduChina
| | - Raju Datla
- Global Institute for Food Security in SaskatoonUniversity of SaskatchewanSaskatoonCanada
| | - Maozhi Ren
- Institute of Urban AgricultureChinese Academy of Agricultural SciencesChengdu National Agricultural Science and Technology CenterChengduChina
- Zhengzhou Research BaseState Key Laboratory of Cotton BiologyZhengzhou UniversityZhengzhouChina
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17
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Sato A, Ikeda K. Genetic and Environmental Contributions to Autism Spectrum Disorder Through Mechanistic Target of Rapamycin. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2021; 2:95-105. [PMID: 36325164 PMCID: PMC9616270 DOI: 10.1016/j.bpsgos.2021.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 02/06/2023] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder that affects an individual’s reciprocal social interaction and communication ability. Numerous genetic and environmental conditions are associated with ASD, including tuberous sclerosis complex, phosphatase and tensin homolog hamartoma tumor syndrome, fragile X syndrome, and neurofibromatosis 1. The pathogenic molecular mechanisms of these diseases are integrated into the hyperactivation of mTORC1 (mechanistic target of rapamycin complex 1). Rodent models of these diseases have shown high mTORC1 activity in the brain and ASD-related behavioral deficits, which were reversed by the mTORC1 inhibitor rapamycin. Environmental stress can also affect this signaling pathway. In utero exposure to valproate caused ASD in offspring and enhanced mTORC1 activity in the brain, which was sensitive to mTORC1 inhibition. mTORC1 is a signaling hub for diverse cellular functions, including protein synthesis, through the phosphorylation of its targets, such as ribosomal protein S6 kinases. Metabotropic glutamate receptor 5–mediated synaptic function is also affected by the dysregulation of mTORC1 activity, such as in fragile X syndrome and tuberous sclerosis complex. Reversing these downstream changes that are associated with mTORC1 activation normalizes behavioral defects in rodents. Despite abundant preclinical evidence, few clinical studies have investigated the treatment of ASD and cognitive deficits. Therapeutics other than mTORC1 inhibitors failed to show efficacy in fragile X syndrome and neurofibromatosis 1. mTORC1 inhibitors have been tested mainly in tuberous sclerosis complex, and their effects on ASD and neuropsychological deficits are promising. mTORC1 is a promising target for the pharmacological treatment of ASD associated with mTORC1 activation.
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18
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Navratilova A, Kovar M, Trakovicka A, Pozgajova M. Nickel induced cell impairments are negatively regulated by the Tor1 kinase in Schizosaccharomyces pombe. World J Microbiol Biotechnol 2021; 37:165. [PMID: 34458935 DOI: 10.1007/s11274-021-03130-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 08/17/2021] [Indexed: 11/26/2022]
Abstract
In our study we investigated the effect of different nickel (NiSO4·6H2O) (Ni) concentrations on cell division, cellular morphology and ionome homeostasis of the eukaryotic model organism Schizosaccharomyces pombe. Target of rapamycin (TOR) protein kinase is one of the key regulators of cell growth under different environmental stresses. We analyzed the effect of Ni on cell strains lacking the Tor1 signaling pathway utilizing light-absorbance spectroscopy, visualization, microscopy and inductively coupled plasma optical emission spectroscopy. Interestingly, our findings revealed that Ni mediated cell growth alterations are noticeably lower in Tor1 deficient cells. Greater size of Tor1 depleted cells reached similar quantitative parameters to wild type cells upon incubation with 400 μM Ni. Differences of ion levels among the two tested yeast strains were detected even before Ni addition. Addition of high concentration (1 mM) of the heavy metal, representing acute contamination, caused considerable changes in the ionome of both strains. Strikingly, Tor1 deficient cells displayed largely reduced Ni content after treatment compared to wild type controls (644.1 ± 49 vs. 2096.8 ± 75 μg/g), suggesting its significant role in Ni trafficking. Together our results predict yet undefined role for the Tor1 signaling in metal uptake and/or metabolism.
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Affiliation(s)
- Alica Navratilova
- Department of Genetics and Breeding Biology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94976, Nitra, Slovakia
| | - Marek Kovar
- Department of Plant Physiology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94976, Nitra, Slovakia
| | - Anna Trakovicka
- Department of Genetics and Breeding Biology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94976, Nitra, Slovakia
| | - Miroslava Pozgajova
- AgroBioTech Research Centre, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94976, Nitra, Slovakia.
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19
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Castel P, Dharmaiah S, Sale MJ, Messing S, Rizzuto G, Cuevas-Navarro A, Cheng A, Trnka MJ, Urisman A, Esposito D, Simanshu DK, McCormick F. RAS interaction with Sin1 is dispensable for mTORC2 assembly and activity. Proc Natl Acad Sci U S A 2021; 118:e2103261118. [PMID: 34380736 PMCID: PMC8379911 DOI: 10.1073/pnas.2103261118] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
RAS proteins are molecular switches that interact with effector proteins when bound to guanosine triphosphate, stimulating downstream signaling in response to multiple stimuli. Although several canonical downstream effectors have been extensively studied and tested as potential targets for RAS-driven cancers, many of these remain poorly characterized. In this study, we undertook a biochemical and structural approach to further study the role of Sin1 as a RAS effector. Sin1 interacted predominantly with KRAS isoform 4A in cells through an atypical RAS-binding domain that we have characterized by X-ray crystallography. Despite the essential role of Sin1 in the assembly and activity of mTORC2, we find that the interaction with RAS is not required for these functions. Cells and mice expressing a mutant of Sin1 that is unable to bind RAS are proficient for activation and assembly of mTORC2. Our results suggest that Sin1 is a bona fide RAS effector that regulates downstream signaling in an mTORC2-independent manner.
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Affiliation(s)
- Pau Castel
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
| | - Srisathiyanarayanan Dharmaiah
- National Cancer Institute (NCI) RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702
| | - Matthew J Sale
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
| | - Simon Messing
- National Cancer Institute (NCI) RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702
| | - Gabrielle Rizzuto
- Department of Anatomic Pathology, University of California, San Francisco, CA 94158
| | - Antonio Cuevas-Navarro
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
| | - Alice Cheng
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
| | - Michael J Trnka
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158
| | - Anatoly Urisman
- Department of Anatomic Pathology, University of California, San Francisco, CA 94158
| | - Dominic Esposito
- National Cancer Institute (NCI) RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702
| | - Dhirendra K Simanshu
- National Cancer Institute (NCI) RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702;
| | - Frank McCormick
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158;
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20
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Ballesteros‐Álvarez J, Andersen JK. mTORC2: The other mTOR in autophagy regulation. Aging Cell 2021; 20:e13431. [PMID: 34250734 PMCID: PMC8373318 DOI: 10.1111/acel.13431] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 06/15/2021] [Accepted: 06/24/2021] [Indexed: 12/13/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) has gathered significant attention as a ubiquitously expressed multimeric kinase with key implications for cell growth, proliferation, and survival. This kinase forms the central core of two distinct complexes, mTORC1 and mTORC2, which share the ability of integrating environmental, nutritional, and hormonal cues but which regulate separate molecular pathways that result in different cellular responses. Particularly, mTORC1 has been described as a major negative regulator of endosomal biogenesis and autophagy, a catabolic process that degrades intracellular components and organelles within the lysosomes and is thought to play a key role in human health and disease. In contrast, the role of mTORC2 in the regulation of autophagy has been considerably less studied despite mounting evidence this complex may regulate autophagy in a different and perhaps complementary manner to that of mTORC1. Genetic ablation of unique subunits is currently being utilized to study the differential effects of the two mTOR complexes. RICTOR is the best‐described subunit specific to mTORC2 and as such has become a useful tool for investigating the specific actions of this complex. The development of complex‐specific inhibitors for mTORC2 is also an area of intense interest. Studies to date have demonstrated that mTORC1/2 complexes each signal to a variety of exclusive downstream molecules with distinct biological roles. Pinpointing the particular effects of these downstream effectors is crucial toward the development of novel therapies aimed at accurately modulating autophagy in the context of human aging and disease.
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21
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Lv Z, Yue Z, Shao Y, Li C, Zhao X, Guo M. mTORC2/Rictor is essential for coelomocyte endocytosis in Apostichopus japonicus. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 118:104000. [PMID: 33444645 DOI: 10.1016/j.dci.2021.104000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
Endocytosis plays an important role in the immune defence systems of invertebrates through the interaction between the mechanical target of rapamycin complex 2 (mTORC2) and the AGC kinase family. Rictor is the most important unique subunit protein of mTORC2 and is thought to regulate almost all functions of mTORC2, including endocytosis. In the present study, a novel invertebrate Rictor homologue was identified from Apostichopus japonicus (designated as AjRictor) via the rapid amplification of cDNA ends (RACE). Spatial expression analysis indicated that AjRictor is ubiquitously expressed in all the examined tissues and has the highest transcript level in coelomocytes. Vibrio splendidus challenge in vivo and lipopolysaccharide (LPS) exposure in vitro could remarkably up-regulate the messenger RNA (mRNA) expression of AjRictor compared with the control group. AjRictor knockdown by 0.49- and 0.69-fold resulted in the significant decrease in endocytosis rate by 0.53- (P < 0.01) and 0.59-fold (P < 0.01) in vivo and in vitro compared with the control group, respectively. Similarly, the treatment of coelomocytes with rapamycin for 24 h and the destruction of the assembly of mTORC2 markedly decreased the endocytosis rate of the coelomocytes by 35.92% (P < 0.05). We detected the expression levels of endocytosis-related molecular markers after AjRictor knockdown and rapamycin treatment to further study the molecular mechanism between mTORC2 and endocytosis. Our results showed that AGC kinase family members (PKCα and Pan1) and the phosphorylation level of AktS473 were remarkably decreased after reducing mTORC2 activity; thus, mTORC2/Rictor plays a key role in the immune regulation of endocytosis in coelomocytes. Our current study indicates that mTORC2/Rictor is involved in the coelomocyte endocytosis of sea cucumber and plays an essential regulation role in defending pathogen invasion.
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Affiliation(s)
- Zhimeng Lv
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
| | - Zongxu Yue
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
| | - Yina Shao
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China.
| | - Chenghua Li
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, PR China.
| | - Xuelin Zhao
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
| | - Ming Guo
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
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22
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Grabowska M, Michałek K, Kędzierska-Kapuza K, Kram A, Gill K, Piasecka M. The long-term effects of rapamycin-based immunosuppressive protocols on the expression of renal aquaporins 1, 2, 3 and 4 water channels in rats. Histol Histopathol 2021; 36:459-474. [PMID: 33634832 DOI: 10.14670/hh-18-321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND To this day, the effect of multi-drug immunosuppressive protocols on renal expression of AQPs is unknown. This study aimed to determine the influence of rapamycin-based multi-drug immunosuppressive regimens on the expression of aquaporins (AQPs) 1, 2, 3, and 4 in the rat kidney. METHODS For 6 months, 24 male Wistar rats were administered immunosuppressants, according to the three-drug protocols used in patients after organ transplantation. The rats were divided into four groups: the control group, the TRP group (tacrolimus, rapamycin, prednisone), the CRP group (cyclosporine A, rapamycin, prednisone), and the MRP group (mycophenolate mofetil, rapamycin, prednisone). Selected red cell indices and total calcium were measured in the blood of rats and quantitative analysis of AQP1, AQP2, AQP3 and AQP4 immunoexpression in the kidneys were performed. RESULTS In the TRP and CRP groups, a mild increase of mean corpuscular hemoglobin concentration, hematocrit and total calcium were observed. Moreover, decreased expression of AQP1-4 was found in all experimental groups, with the highest decrease in the CRP group. CONCLUSIONS The long-term immunosuppressive treatment using multi-drug protocols decreased AQP1-4 expressions in renal tubules, possibly leading to impaired urine-concentrating ability in rat.
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Affiliation(s)
- Marta Grabowska
- Department of Histology and Developmental Biology, Pomeranian Medical University, Szczecin, Poland
| | - Katarzyna Michałek
- Department of Physiology, Cytobiology and Proteomics, West Pomeranian University of Technology, Szczecin, Poland
| | - Karolina Kędzierska-Kapuza
- Department of Gastroenterological Surgery and Transplantation, Central Hospital of Ministry of Internal Affairs and Administration in Warsaw, Medical Center for Postgraduate Education, Warsaw, Poland
| | - Andrzej Kram
- Department of Pathology, West Pomeranian Oncology Center, Szczecin, Poland
| | - Kamil Gill
- Department of Histology and Developmental Biology, Pomeranian Medical University, Szczecin, Poland
| | - Małgorzata Piasecka
- Department of Histology and Developmental Biology, Pomeranian Medical University, Szczecin, Poland.
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23
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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: 49] [Impact Index Per Article: 12.3] [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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24
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Schmidt O, Weyer Y, Sprenger S, Widerin MA, Eising S, Baumann V, Angelova M, Loewith R, Stefan CJ, Hess MW, Fröhlich F, Teis D. TOR complex 2 (TORC2) signaling and the ESCRT machinery cooperate in the protection of plasma membrane integrity in yeast. J Biol Chem 2020; 295:12028-12044. [PMID: 32611771 PMCID: PMC7443507 DOI: 10.1074/jbc.ra120.013222] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 06/24/2020] [Indexed: 12/26/2022] Open
Abstract
The endosomal sorting complexes required for transport (ESCRT) mediate evolutionarily conserved membrane remodeling processes. Here, we used budding yeast (Saccharomyces cerevisiae) to explore how the ESCRT machinery contributes to plasma membrane (PM) homeostasis. We found that in response to reduced membrane tension and inhibition of TOR complex 2 (TORC2), ESCRT-III/Vps4 assemblies form at the PM and help maintain membrane integrity. In turn, the growth of ESCRT mutants strongly depended on TORC2-mediated homeostatic regulation of sphingolipid (SL) metabolism. This was caused by calcineurin-dependent dephosphorylation of Orm2, a repressor of SL biosynthesis. Calcineurin activity impaired Orm2 export from the endoplasmic reticulum (ER) and thereby hampered its subsequent endosome and Golgi-associated degradation (EGAD). The ensuing accumulation of Orm2 at the ER in ESCRT mutants necessitated TORC2 signaling through its downstream kinase Ypk1, which repressed Orm2 and prevented a detrimental imbalance of SL metabolism. Our findings reveal compensatory cross-talk between the ESCRT machinery, calcineurin/TORC2 signaling, and the EGAD pathway important for the regulation of SL biosynthesis and the maintenance of PM homeostasis.
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Affiliation(s)
- Oliver Schmidt
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
| | - Yannick Weyer
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Simon Sprenger
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Michael A Widerin
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Sebastian Eising
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Verena Baumann
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Mihaela Angelova
- Cancer Evolution and Genome Instability Laboratory, Francis Crick Institute, London, United Kingdom
| | - Robbie Loewith
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Christopher J Stefan
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Michael W Hess
- Institute for Histology and Embryology, Medical University of Innsbruck, Innsbruck, Austria
| | - Florian Fröhlich
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - David Teis
- Institute for Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
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25
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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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26
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Athanasopoulos A, André B, Sophianopoulou V, Gournas C. Fungal plasma membrane domains. FEMS Microbiol Rev 2020; 43:642-673. [PMID: 31504467 DOI: 10.1093/femsre/fuz022] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/25/2019] [Indexed: 12/11/2022] Open
Abstract
The plasma membrane (PM) performs a plethora of physiological processes, the coordination of which requires spatial and temporal organization into specialized domains of different sizes, stability, protein/lipid composition and overall architecture. Compartmentalization of the PM has been particularly well studied in the yeast Saccharomyces cerevisiae, where five non-overlapping domains have been described: The Membrane Compartments containing the arginine permease Can1 (MCC), the H+-ATPase Pma1 (MCP), the TORC2 kinase (MCT), the sterol transporters Ltc3/4 (MCL), and the cell wall stress mechanosensor Wsc1 (MCW). Additional cortical foci at the fungal PM are the sites where clathrin-dependent endocytosis occurs, the sites where the external pH sensing complex PAL/Rim localizes, and sterol-rich domains found in apically grown regions of fungal membranes. In this review, we summarize knowledge from several fungal species regarding the organization of the lateral PM segregation. We discuss the mechanisms of formation of these domains, and the mechanisms of partitioning of proteins there. Finally, we discuss the physiological roles of the best-known membrane compartments, including the regulation of membrane and cell wall homeostasis, apical growth of fungal cells and the newly emerging role of MCCs as starvation-protective membrane domains.
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Affiliation(s)
- Alexandros Athanasopoulos
- Microbial Molecular Genetics Laboratory, Institute of Biosciences and Applications, National Centre for Scientific Research 'Demokritos,' Patr. Grigoriou E & 27 Neapoleos St. 15341, Agia Paraskevi, Greece
| | - Bruno André
- Molecular Physiology of the Cell laboratory, Université Libre de Bruxelles (ULB), Institut de Biologie et de Médecine Moléculaires, rue des Pr Jeener et Brachet 12, 6041, Gosselies, Belgium
| | - Vicky Sophianopoulou
- Microbial Molecular Genetics Laboratory, Institute of Biosciences and Applications, National Centre for Scientific Research 'Demokritos,' Patr. Grigoriou E & 27 Neapoleos St. 15341, Agia Paraskevi, Greece
| | - Christos Gournas
- Microbial Molecular Genetics Laboratory, Institute of Biosciences and Applications, National Centre for Scientific Research 'Demokritos,' Patr. Grigoriou E & 27 Neapoleos St. 15341, Agia Paraskevi, Greece
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27
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Laribee RN, Weisman R. Nuclear Functions of TOR: Impact on Transcription and the Epigenome. Genes (Basel) 2020; 11:E641. [PMID: 32532005 PMCID: PMC7349558 DOI: 10.3390/genes11060641] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/04/2020] [Accepted: 06/09/2020] [Indexed: 12/15/2022] Open
Abstract
The target of rapamycin (TOR) protein kinase is at the core of growth factor- and nutrient-dependent signaling pathways that are well-known for their regulation of metabolism, growth, and proliferation. However, TOR is also involved in the regulation of gene expression, genomic and epigenomic stability. TOR affects nuclear functions indirectly through its activity in the cytoplasm, but also directly through active nuclear TOR pools. The mechanisms by which TOR regulates its nuclear functions are less well-understood compared with its cytoplasmic activities. TOR is an important pharmacological target for several diseases, including cancer, metabolic and neurological disorders. Thus, studies of the nuclear functions of TOR are important for our understanding of basic biological processes, as well as for clinical implications.
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Affiliation(s)
- R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and Center for Cancer Research, University of Tennessee Health Science Center, 19 South Manassas, Cancer Research Building Rm 318, Memphis, TN 38163, USA
| | - Ronit Weisman
- Department of Natural and Life Sciences, The Open University of Israel, University Road 1, Ra’anana 4353701, Israel
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28
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Tiedemann K, Hussein O, Komarova SV. Role of Altered Metabolic Microenvironment in Osteolytic Metastasis. Front Cell Dev Biol 2020; 8:435. [PMID: 32582711 PMCID: PMC7290111 DOI: 10.3389/fcell.2020.00435] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 05/08/2020] [Indexed: 12/17/2022] Open
Abstract
Metastatic bone disease is generally incurable and leads to pathological fractures, pain, hypercalcemia, spinal cord compression and decreased mobility. The skeleton is the major site of bone metastases from solid cancers, including breast and prostate carcinoma. Bone metastasis is facilitated by activation of bone-resorbing osteoclasts, terminally differentiated multinucleated cells formed by fusion from monocytic precursors. Cancer cells are known to produce specific factors that stimulate osteoclast differentiation and function. Of interest, cancer cells are also known to alter their own bioenergetics increasing the use of glycolysis for their survival and function. Such change in energy utilization by cancer cells would result in altered levels of cell-permeable metabolites, including glucose, lactate, and pyruvate. Osteoclast resorption is energy-expensive, and we have previously demonstrated that during differentiation osteoclasts actively adapt to their bioenergetics microenvironment. We hypothesize that altered bioenergetics state of cancer cells will also modify the bioenergetics substrate availability for the tissue-resident bone cells, potentially creating a favorable milieu for pathological osteolysis. The goals of this review are to analyze how metastasizing cancer cells change the availability of energy substrates in bone microenvironment; and to assess how the altered bioenergetics may affect osteoclast differentiation and activity.
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Affiliation(s)
- Kerstin Tiedemann
- Faculty of Dentistry, McGill University, Montréal, QC, Canada.,Shriners Hospitals for Children - Canada, Montréal, QC, Canada
| | - Osama Hussein
- Department of Surgery, Mansoura University Cancer Center, Mansoura, Egypt
| | - Svetlana V Komarova
- Faculty of Dentistry, McGill University, Montréal, QC, Canada.,Shriners Hospitals for Children - Canada, Montréal, QC, Canada
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29
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Gui Y, Hou Q, Lu Q, Dai C, Li J. Loss of Rictor in tubular cells exaggerates lipopolysaccharide induced renal inflammation and acute kidney injury via Yap/Taz-NF-κB axis. Cell Death Discov 2020; 6:40. [PMID: 32528729 PMCID: PMC7260239 DOI: 10.1038/s41420-020-0274-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/06/2020] [Accepted: 05/12/2020] [Indexed: 12/12/2022] Open
Abstract
Our previous study demonstrated that the mammalian target of rapamycin complex 2 (mTORC2) signaling alleviates renal inflammation and protects against cisplatin-induced AKI. However, the underlying mechanisms for mTORC2 in regulating renal inflammation in AKI remain to be determined. In this study, we found that lipopolysaccharide (LPS) could activate mTORC2 signaling in NRK-52E cells, and blockage of mTORC2 signaling led to Yap/Taz degradation, which in turn activated NF-κB signaling and induced inflammatory cytokines secretion. Overexpression of constitutively active Taz (Taz-S89A) could attenuate the inflammation-amplified role of mTORC2 blockage. In mouse models, tubule-specific deletion of Rictor had higher blood urea nitrogen level, severe morphological injury as well as more inflammatory cells accumulation compared with those in their littermate controls. Overall, these results demonstrate that mTORC2 signaling protects against renal inflammation and dictates the outcome of AKI by modulating Yap/Taz degradation.
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Affiliation(s)
- Yuan Gui
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003 China
- Division of Nephrology, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242 USA
| | - Qing Hou
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003 China
| | - Qingmiao Lu
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003 China
| | - Chunsun Dai
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, 262 North Zhongshan Road, Nanjing, Jiangsu 210003 China
| | - Jianzhong Li
- Department of Nephrology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006 China
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30
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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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31
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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: 369] [Impact Index Per Article: 92.3] [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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32
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Lin Z, Zhang X, Wang J, Liu W, Liu Q, Ye Y, Dai B, Guo D, Zhang P, Yang P, Zhang R, Wang L, Dou K. Translationally controlled tumor protein promotes liver regeneration by activating mTORC2/AKT signaling. Cell Death Dis 2020; 11:58. [PMID: 31974368 PMCID: PMC6978394 DOI: 10.1038/s41419-020-2231-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 12/29/2019] [Accepted: 01/07/2020] [Indexed: 12/17/2022]
Abstract
Translationally controlled tumor protein (TCTP), which is a protein characterized by its potent proliferation promoting activity, has been well studied in the area of growth and tumorigenesis. However, the specific role of TCTP in liver regeneration (LR) and its underlying mechanism remains unclear. In order to investigate the contribution of TCTP during LR, heterozygous TCTP mice were generated, and a mimic LR model was applied to TCTP-knockdown (KD) hepatic cell lines. The results revealed that TCTP-KD impaired LR in mice, and manifested as the following aspects: delayed proliferation of hepatocytes, accompanied by disruption of the mRNA expression of markers of the cell cycle, degenerated lipid metabolism, and abnormal immune response. Furthermore, it was found out that TCTP activated PI3K/AKT signaling by regulating mTORC2. Lastly, the increasing rate of serum TCTP positively correlated to the recovery of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) after liver resection in humans. In summary, the present study is the first to reveal the crucial role of intracellular TCTP in LR.
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Affiliation(s)
- Zhibin Lin
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Xuan Zhang
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Jianlin Wang
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Wei Liu
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Qi Liu
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Yuchen Ye
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Bin Dai
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Dongnan Guo
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Pengcheng Zhang
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Peijun Yang
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Ruohan Zhang
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.
| | - Lin Wang
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.
| | - Kefeng Dou
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.
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33
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Ruan C, Ouyang X, Liu H, Li S, Jin J, Tang W, Xia Y, Su B. Sin1-mediated mTOR signaling in cell growth, metabolism and immune response. Natl Sci Rev 2019; 6:1149-1162. [PMID: 34691993 PMCID: PMC8291397 DOI: 10.1093/nsr/nwz171] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/22/2019] [Accepted: 10/22/2019] [Indexed: 12/22/2022] Open
Abstract
Abstract
The mammalian target of rapamycin (mTOR) is an evolutionarily conserved Ser/Thr protein kinase with essential cellular function via processing various extracellular and intracellular inputs. Two distinct multi-protein mTOR complexes (mTORC), mTORC1 and mTORC2, have been identified and well characterized in eukaryotic cells from yeast to human. Sin1, which stands for Sty1/Spc1-interacting protein1, also known as mitogen-activated protein kinase (MAPK) associated protein (MAPKAP)1, is an evolutionarily conserved adaptor protein. Mammalian Sin1 interacts with many cellular proteins, but it has been widely studied as an essential component of mTORC2, and it is crucial not only for the assembly of mTORC2 but also for the regulation of its substrate specificity. In this review, we summarize our current knowledge of the structure and functions of Sin1, focusing specifically on its protein interaction network and its roles in the mTOR pathway that could account for various cellular functions of mTOR in growth, metabolism, immunity and cancer.
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Affiliation(s)
- Chun Ruan
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xinxing Ouyang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Hongzhi Liu
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Song Li
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jingsi Jin
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Weiyi Tang
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yu Xia
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bing Su
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
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34
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Reidman S, Cohen A, Kupiec M, Weisman R. The cytosolic form of aspartate aminotransferase is required for full activation of TOR complex 1 in fission yeast. J Biol Chem 2019; 294:18244-18255. [PMID: 31641022 DOI: 10.1074/jbc.ra119.010101] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 10/18/2019] [Indexed: 12/17/2022] Open
Abstract
The evolutionarily conserved TOR complex 1 (TORC1) activates cell growth and proliferation in response to nutritional signals. In the fission yeast Schizosaccharomyces pombe, TORC1 is essential for vegetative growth, and its activity is regulated in response to nitrogen quantity and quality. Yet, how TORC1 senses nitrogen is poorly understood. Rapamycin, a specific TOR inhibitor, inhibits growth in S. pombe only under conditions in which the activity of TORC1 is compromised. In a genetic screen for rapamycin-sensitive mutations, we isolated caa1-1, a loss-of-function mutation of the cytosolic form of aspartate aminotransferase (Caa1). We demonstrate that loss of caa1 + partially mimics loss of TORC1 activity and that Caa1 is required for full TORC1 activity. Disruption of caa1 + resulted in aspartate auxotrophy, a finding that prompted us to assess the role of aspartate in TORC1 activation. We found that the amino acids glutamine, asparagine, arginine, aspartate, and serine activate TORC1 most efficiently following nitrogen starvation. The glutamine synthetase inhibitor l-methionine sulfoximine abolished the ability of asparagine, arginine, aspartate, or serine, but not that of glutamine, to induce TORC1 activity, consistent with a central role for glutamine in activating TORC1. Neither addition of aspartate nor addition of glutamine restored TORC1 activity in caa1-deleted cells or in cells carrying a Caa1 variant with a catalytic site substitution, suggesting that the catalytic activity of Caa1 is required for TORC1 activation. Taken together, our results reveal the contribution of the key metabolic enzyme Caa1 to TORC1 activity in S. pombe.
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Affiliation(s)
- Sophie Reidman
- School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Adiel Cohen
- Department of Natural and Life Sciences, the Open University of Israel, University Road 1, 4353701 Ra'anana, Israel
| | - Martin Kupiec
- School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Ronit Weisman
- Department of Natural and Life Sciences, the Open University of Israel, University Road 1, 4353701 Ra'anana, Israel.
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35
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Abstract
We review the mechanisms responsible for amino acid homeostasis in Saccharomyces cerevisiae and other fungi. Amino acid homeostasis is essential for cell growth and survival. Hence, the de novo synthesis reactions, metabolic conversions, and transport of amino acids are tightly regulated. Regulation varies from nitrogen pool sensing to control by individual amino acids and takes place at the gene (transcription), protein (posttranslational modification and allostery), and vesicle (trafficking and endocytosis) levels. The pools of amino acids are controlled via import, export, and compartmentalization. In yeast, the majority of the amino acid transporters belong to the APC (amino acid-polyamine-organocation) superfamily, and the proteins couple the uphill transport of amino acids to the electrochemical proton gradient. Although high-resolution structures of yeast amino acid transporters are not available, homology models have been successfully exploited to determine and engineer the catalytic and regulatory functions of the proteins. This has led to a further understanding of the underlying mechanisms of amino acid sensing and subsequent downregulation of transport. Advances in optical microscopy have revealed a new level of regulation of yeast amino acid transporters, which involves membrane domain partitioning. The significance and the interrelationships of the latest discoveries on amino acid homeostasis are put in context.
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36
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Schmidt O, Weyer Y, Baumann V, Widerin MA, Eising S, Angelova M, Schleiffer A, Kremser L, Lindner H, Peter M, Fröhlich F, Teis D. Endosome and Golgi-associated degradation (EGAD) of membrane proteins regulates sphingolipid metabolism. EMBO J 2019; 38:e101433. [PMID: 31368600 PMCID: PMC6669922 DOI: 10.15252/embj.2018101433] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 05/08/2019] [Accepted: 05/08/2019] [Indexed: 12/13/2022] Open
Abstract
Cellular homeostasis requires the ubiquitin-dependent degradation of membrane proteins. This was assumed to be mediated exclusively either by endoplasmic reticulum-associated degradation (ERAD) or by endosomal sorting complexes required for transport (ESCRT)-dependent lysosomal degradation. We identified in Saccharomyces cerevisiae an additional pathway that selectively extracts membrane proteins at Golgi and endosomes for degradation by cytosolic proteasomes. One endogenous substrate of this endosome and Golgi-associated degradation pathway (EGAD) is the ER-resident membrane protein Orm2, a negative regulator of sphingolipid biosynthesis. Orm2 degradation is initiated by phosphorylation, which triggers its ER export. Once on Golgi and endosomes, Orm2 is poly-ubiquitinated by the membrane-embedded "Defective in SREBP cleavage" (Dsc) ubiquitin ligase complex. Cdc48/VCP then extracts ubiquitinated Orm2 from membranes, which is tightly coupled to the proteasomal degradation of Orm2. Thereby, EGAD prevents the accumulation of Orm2 at the ER and in post-ER compartments and promotes the controlled de-repression of sphingolipid biosynthesis. Thus, the selective degradation of membrane proteins by EGAD contributes to proteostasis and lipid homeostasis in eukaryotic cells.
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Affiliation(s)
- Oliver Schmidt
- Division of Cell BiologyBiocenterMedical University of InnsbruckInnsbruckAustria
| | - Yannick Weyer
- Division of Cell BiologyBiocenterMedical University of InnsbruckInnsbruckAustria
| | - Verena Baumann
- Division of Cell BiologyBiocenterMedical University of InnsbruckInnsbruckAustria
- Present address:
MFPLUniversity of ViennaViennaAustria
| | - Michael A Widerin
- Division of Cell BiologyBiocenterMedical University of InnsbruckInnsbruckAustria
| | - Sebastian Eising
- Department of Biology/ChemistryUniversity of OsnabrückOsnabrückGermany
| | - Mihaela Angelova
- INSERMLaboratory of Integrative Cancer ImmunologySorbonne UniversitéSorbonne Paris CitéUniversité Paris DescartesCentre de Recherche des CordeliersUniversité Paris DiderotParisFrance
| | - Alexander Schleiffer
- Research Institute of Molecular Pathology (IMP)Vienna Biocenter (VBC)ViennaAustria
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna Biocenter (VBC)ViennaAustria
| | - Leopold Kremser
- Division of Clinical Biochemistry, Protein Micro‐Analysis FacilityBiocenterMedical University of InnsbruckInnsbruckAustria
| | - Herbert Lindner
- Division of Clinical Biochemistry, Protein Micro‐Analysis FacilityBiocenterMedical University of InnsbruckInnsbruckAustria
| | | | - Florian Fröhlich
- Department of Biology/ChemistryUniversity of OsnabrückOsnabrückGermany
| | - David Teis
- Division of Cell BiologyBiocenterMedical University of InnsbruckInnsbruckAustria
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37
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Busto JV, Wedlich-Söldner R. Integration Through Separation - The Role of Lateral Membrane Segregation in Nutrient Uptake. Front Cell Dev Biol 2019; 7:97. [PMID: 31294021 PMCID: PMC6603244 DOI: 10.3389/fcell.2019.00097] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 05/21/2019] [Indexed: 12/12/2022] Open
Abstract
Nutrient transporters are prominent and ubiquitous components of the plasma membrane in all cell types. Their expression and regulation are tightly linked to the cells’ needs. Environmental factors such as nutrient starvation or osmotic stress prompt an acute remodeling of transporters and the plasma membrane to efficiently maintain homeostasis in cell metabolism. Lateral confinement of nutrient transporters through dynamic segregation within the plasma membrane has recently emerged as an important phenomenon that facilitates spatiotemporal control of nutrient uptake and metabolic regulation. Here, we review recent studies highlighting the mechanisms connecting the function of amino acid permeases with their endocytic turnover and lateral segregation within the plasma membrane. These findings indicate that actively controlled lateral compartmentalization of plasma membrane components constitutes an important level of regulation during acute cellular adaptations.
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Affiliation(s)
- Jon V Busto
- Institute of Cell Dynamics and Imaging, University of Münster, Münster, Germany.,Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry, University of the Basque Country, Leioa, Spain
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38
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Riggi M, Bourgoint C, Macchione M, Matile S, Loewith R, Roux A. TORC2 controls endocytosis through plasma membrane tension. J Cell Biol 2019; 218:2265-2276. [PMID: 31123183 PMCID: PMC6605812 DOI: 10.1083/jcb.201901096] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 04/11/2019] [Accepted: 05/06/2019] [Indexed: 12/27/2022] Open
Abstract
Target of rapamycin complex 2 (TORC2) is a conserved protein kinase that regulates multiple plasma membrane (PM)-related processes, including endocytosis. Direct, chemical inhibition of TORC2 arrests endocytosis but with kinetics that is relatively slow and therefore inconsistent with signaling being mediated solely through simple phosphorylation cascades. Here, we show that in addition to and independently from regulation of the phosphorylation of endocytic proteins, TORC2 also controls endocytosis by modulating PM tension. Elevated PM tension, upon TORC2 inhibition, impinges on endocytosis at two different levels by (1) severing the bonds between the PM adaptor proteins Sla2 and Ent1 and the actin cytoskeleton and (2) hindering recruitment of Rvs167, an N-BAR-containing protein important for vesicle fission to endocytosis sites. These results underline the importance of biophysical cues in the regulation of cellular and molecular processes.
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Affiliation(s)
- Margot Riggi
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland.,Department of Biochemistry, University of Geneva, Geneva, Switzerland.,iGE3 Institute of Genetics and Genomics of Geneva, Geneva, Switzerland.,Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland
| | - Clélia Bourgoint
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Mariano Macchione
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland.,Department of Organic Chemistry, University of Geneva, Geneva, Switzerland
| | - Stefan Matile
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland.,Department of Organic Chemistry, University of Geneva, Geneva, Switzerland
| | - Robbie Loewith
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland .,iGE3 Institute of Genetics and Genomics of Geneva, Geneva, Switzerland.,Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland
| | - Aurélien Roux
- Department of Biochemistry, University of Geneva, Geneva, Switzerland .,Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland
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39
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Locke MN, Thorner J. Regulation of TORC2 function and localization by Rab5 GTPases in Saccharomyces cerevisiae. Cell Cycle 2019; 18:1084-1094. [PMID: 31068077 DOI: 10.1080/15384101.2019.1616999] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The evolutionarily conserved Target of Rapamycin (TOR) complex-2 (TORC2) is an essential regulator of plasma membrane homeostasis in budding yeast (Saccharomyces cerevisiae). In this yeast, TORC2 phosphorylates and activates the effector protein kinase Ypk1 and its paralog Ypk2. These protein kinases, in turn, carry out all the crucial functions of TORC2 by phosphorylating and thereby controlling the activity of at least a dozen downstream substrates. A previously uncharacterized interplay between the Rab5 GTPases and TORC2 signaling was uncovered through analysis of a newly suspected Ypk1 target. Muk1, one of two guanine nucleotide exchange factors for the Rab5 GTPases, was found to be a physiologically relevant Ypk1 substrate; and, genetic analysis indicates that Ypk1-mediated phosphorylation activates the guanine nucleotide exchange activity of Muk1. Second, it was demonstrated both in vivo and in vitro that the GTP-bound state of the Rab5 GTPase Vps21/Ypt51 physically associates with TORC2 and acts as a direct positive effector required for full TORC2 activity. These interrelationships provide a self-reinforcing control circuit for sustained up-regulation of TORC2-Ypk1 signaling. In this overview, we summarize the experimental basis of these findings, their implications, and speculate as to the molecular basis for Rab5-mediated TORC2 activation.
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Affiliation(s)
- Melissa N Locke
- a Division of Biochemistry, Biophysics & Structural Biology, and Division of Cell & Developmental Biology, Department of Molecular and Cell Biology , University of California at Berkeley , Berkeley , CA , USA
| | - Jeremy Thorner
- a Division of Biochemistry, Biophysics & Structural Biology, and Division of Cell & Developmental Biology, Department of Molecular and Cell Biology , University of California at Berkeley , Berkeley , CA , USA
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40
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Hwang Y, Kim LC, Song W, Edwards DN, Cook RS, Chen J. Disruption of the Scaffolding Function of mLST8 Selectively Inhibits mTORC2 Assembly and Function and Suppresses mTORC2-Dependent Tumor Growth In Vivo. Cancer Res 2019; 79:3178-3184. [PMID: 31085701 DOI: 10.1158/0008-5472.can-18-3658] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 04/05/2019] [Accepted: 05/08/2019] [Indexed: 12/24/2022]
Abstract
mTOR is a serine/threonine kinase that acts in two distinct complexes, mTORC1 and mTORC2, and is dysregulated in many diseases including cancer. mLST8 is a shared component of both mTORC1 and mTORC2, yet little is known regarding how mLST8 contributes to assembly and activity of the mTOR complexes. Here we assessed mLST8 loss in a panel of normal and cancer cells and observed little to no impact on assembly or activity of mTORC1. However, mLST8 loss blocked mTOR association with mTORC2 cofactors RICTOR and SIN1, thus abrogating mTORC2 activity. Similarly, a single pair of mutations on mLST8 with a corresponding mutation on mTOR interfered with mTORC2 assembly and activity without affecting mTORC1. We also discovered a direct interaction between mLST8 and the NH2-terminal domain of the mTORC2 cofactor SIN1. In PTEN-null prostate cancer xenografts, mLST8 mutations disrupting the mTOR interaction motif inhibited AKT S473 phosphorylation and decreased tumor cell proliferation and tumor growth in vivo. Together, these data suggest that the scaffolding function of mLST8 is critical for assembly and activity of mTORC2, but not mTORC1, an observation that could enable therapeutic mTORC2-selective inhibition as a therapeutic strategy. SIGNIFICANCE: These findings show that mLST8 functions as a scaffold to maintain mTORC2 integrity and kinase activity, unveiling a new avenue for development of mTORC2-specific inhibitors.
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Affiliation(s)
- Yoonha Hwang
- Veterans Affairs Medical Center, Tennessee Valley Healthcare System, Nashville, Tennessee
- Division of Rheumatology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Laura C Kim
- Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee
| | - Wenqiang Song
- Veterans Affairs Medical Center, Tennessee Valley Healthcare System, Nashville, Tennessee
- Division of Rheumatology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Deanna N Edwards
- Veterans Affairs Medical Center, Tennessee Valley Healthcare System, Nashville, Tennessee
- Division of Rheumatology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Rebecca S Cook
- Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee
- Deparment of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
- Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee
| | - Jin Chen
- Veterans Affairs Medical Center, Tennessee Valley Healthcare System, Nashville, Tennessee.
- Division of Rheumatology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
- Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee
- Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee
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41
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Dereli Eke E, Arga KY, Dikicioglu D, Eraslan S, Erkol E, Celik A, Kirdar B, Di Camillo B. Identification of Novel Components of Target-of-Rapamycin Signaling Pathway by Network-Based Multi-Omics Integrative Analysis. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2019; 23:274-284. [PMID: 30985253 DOI: 10.1089/omi.2019.0021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Target of rapamycin (TOR) is a major signaling pathway and regulator of cell growth. TOR serves as a hub of many signaling routes, and is implicated in the pathophysiology of numerous human diseases, including cancer, diabetes, and neurodegeneration. Therefore, elucidation of unknown components of TOR signaling that could serve as potential biomarkers and drug targets has a great clinical importance. In this study, our aim is to integrate transcriptomics, interactomics, and regulomics data in Saccharomyces cerevisiae using a network-based multiomics approach to enlighten previously unidentified, potential components of TOR signaling. We constructed the TOR-signaling protein interaction network, which was used as a template to search for TOR-mediated rapamycin and caffeine signaling paths. We scored the paths passing from at least one component of TOR Complex 1 or 2 (TORC1/TORC2) using the co-expression levels of the genes in the transcriptome data of the cells grown in the presence of rapamycin or caffeine. The resultant network revealed seven hitherto unannotated proteins, namely, Atg14p, Rim20p, Ret2p, Spt21p, Ylr257wp, Ymr295cp, and Ygr017wp, as potential components of TOR-mediated rapamycin and caffeine signaling in yeast. Among these proteins, we suggest further deciphering of the role of Ylr257wp will be particularly informative in the future because it was the only protein whose removal from the constructed network hindered the signal transduction to the TORC1 effector kinase Npr1p. In conclusion, this study underlines the value of network-based multiomics integrative data analysis in discovering previously unidentified components of the signaling networks by revealing potential components of TOR signaling for future experimental validation.
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Affiliation(s)
- Elif Dereli Eke
- 1 Department of Information Engineering, University of Padua, Padua, Italy
- 2 Department of Chemical Engineering, Bogazici University, Istanbul, Turkey
| | - Kazim Yalcin Arga
- 3 Department of Bioengineering, Marmara University, Istanbul, Turkey
| | - Duygu Dikicioglu
- 2 Department of Chemical Engineering, Bogazici University, Istanbul, Turkey
- 4 Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | - Serpil Eraslan
- 2 Department of Chemical Engineering, Bogazici University, Istanbul, Turkey
- 5 Diagnostic Centre for Genetic Diseases, Koc University Hospital, Istanbul, Turkey
| | - Emir Erkol
- 6 Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkey
| | - Arzu Celik
- 6 Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkey
| | - Betul Kirdar
- 2 Department of Chemical Engineering, Bogazici University, Istanbul, Turkey
| | - Barbara Di Camillo
- 1 Department of Information Engineering, University of Padua, Padua, Italy
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Martinez Marshall MN, Emmerstorfer-Augustin A, Leskoske KL, Zhang LH, Li B, Thorner J. Analysis of the roles of phosphatidylinositol-4,5- bisphosphate and individual subunits in assembly, localization, and function of Saccharomyces cerevisiae target of rapamycin complex 2. Mol Biol Cell 2019; 30:1555-1574. [PMID: 30969890 PMCID: PMC6724684 DOI: 10.1091/mbc.e18-10-0682] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Eukaryotic cell survival requires maintenance of plasma membrane (PM) homeostasis in response to environmental insults and changes in lipid metabolism. In yeast, a key regulator of PM homeostasis is target of rapamycin (TOR) complex 2 (TORC2), a multiprotein complex containing the evolutionarily conserved TOR protein kinase isoform Tor2. PM localization is essential for TORC2 function. One core TORC2 subunit (Avo1) and two TORC2-associated regulators (Slm1 and Slm2) contain pleckstrin homology (PH) domains that exhibit specificity for binding phosphatidylinositol-4,5-bisphosphate (PtdIns4,5P2). To investigate the roles of PtdIns4,5P2 and constituent subunits of TORC2, we used auxin-inducible degradation to systematically eliminate these factors and then examined localization, association, and function of the remaining TORC2 components. We found that PtdIns4,5P2 depletion significantly reduced TORC2 activity, yet did not prevent PM localization or disassembly of TORC2. Moreover, truncated Avo1 (lacking its C-terminal PH domain) was still recruited to the PM and supported growth. Even when all three PH-containing proteins were absent, the remaining TORC2 subunits were PM-bound. Revealingly, Avo3 localized to the PM independent of both Avo1 and Tor2, whereas both Tor2 and Avo1 required Avo3 for their PM anchoring. Our findings provide new mechanistic information about TORC2 and pinpoint Avo3 as pivotal for TORC2 PM localization and assembly in vivo.
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Affiliation(s)
- Maria Nieves Martinez Marshall
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Anita Emmerstorfer-Augustin
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Kristin L Leskoske
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Lydia H Zhang
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Biyun Li
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Jeremy Thorner
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
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43
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Chiarini F, Evangelisti C, Lattanzi G, McCubrey JA, Martelli AM. Advances in understanding the mechanisms of evasive and innate resistance to mTOR inhibition in cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:1322-1337. [PMID: 30928610 DOI: 10.1016/j.bbamcr.2019.03.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 03/22/2019] [Accepted: 03/26/2019] [Indexed: 12/12/2022]
Abstract
The development of drug-resistance by neoplastic cells is recognized as a major cause of targeted therapy failure and disease progression. The mechanistic (previously mammalian) target of rapamycin (mTOR) is a highly conserved Ser/Thr kinase that acts as the catalytic subunit of two structurally and functionally distinct large multiprotein complexes, referred to as mTOR complex 1 (mTORC1) and mTORC2. Both mTORC1 and mTORC2 play key roles in a variety of healthy cell types/tissues by regulating physiological anabolic and catabolic processes in response to external cues. However, a body of evidence identified aberrant activation of mTOR signaling as a common event in many human tumors. Therefore, mTOR is an attractive target for therapeutic targeting in cancer and this fact has driven the development of numerous mTOR inhibitors, several of which have progressed to clinical trials. Nevertheless, mTOR inhibitors have met with a very limited success as anticancer therapeutics. Among other reasons, this failure was initially ascribed to the activation of several compensatory signaling pathways that dampen the efficacy of mTOR inhibitors. The discovery of these regulatory feedback mechanisms greatly contributed to a better understanding of cancer cell resistance to mTOR targeting agents. However, over the last few years, other mechanisms of resistance have emerged, including epigenetic alterations, compensatory metabolism rewiring and the occurrence of mTOR mutations. In this article, we provide the reader with an updated overview of the mechanisms that could explain resistance of cancer cells to the various classes of mTOR inhibitors.
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Affiliation(s)
- Francesca Chiarini
- CNR Institute of Molecular Genetics, 40136 Bologna, BO, Italy; IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, BO, Italy
| | - Camilla Evangelisti
- CNR Institute of Molecular Genetics, 40136 Bologna, BO, Italy; IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, BO, Italy
| | - Giovanna Lattanzi
- CNR Institute of Molecular Genetics, 40136 Bologna, BO, Italy; IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, BO, Italy
| | - James A McCubrey
- Department of Microbiology & Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
| | - Alberto M Martelli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, BO, Italy.
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44
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Li L, Zhu T, Song Y, Luo X, Feng L, Zhuo F, Li F, Ren M. Functional Characterization of Target of Rapamycin Signaling in Verticillium dahliae. Front Microbiol 2019; 10:501. [PMID: 30918504 PMCID: PMC6424901 DOI: 10.3389/fmicb.2019.00501] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 02/27/2019] [Indexed: 12/11/2022] Open
Abstract
More than 200 plants have been suffering from Verticillium wilt caused by Verticillium dahliae (V. dahliae) across the world. The target of rapamycin (TOR) is a lethal gene and controls cell growth and development in various eukaryotes, but little is known about TOR signaling in V. dahliae. Here, we found that V. dahliae strain is hypersensitive to rapamycin in the presence of rapamycin binding protein VdFKBP12 while the deletion mutant aaavdfkbp12 is insensitive to rapamycin. Heterologous expressing VdFKBP12 in Arabidopsis conferred rapamycin sensitivity, indicating that VdFKBP12 can bridge the interaction between rapamycin and TOR across species. The key across species of TOR complex 1 (TORC1) and TORC2 have been identified in V. dahliae, suggesting that TOR signaling pathway is evolutionarily conserved in eukaryotic species. Furthermore, the RNA-seq analysis showed that ribosomal biogenesis, RNA polymerase II transcription factors and many metabolic processes were significantly suppressed in rapamycin treated cells of V. dahliae. Importantly, transcript levels of genes associated with cell wall degrading enzymes (CWEDs) were dramatically down-regulated in TOR-inhibited cells. Further infection assay showed that the pathogenicity of V. dahliae and occurrence of Verticillium wilt can be blocked in the presence of rapamycin. These observations suggested that VdTOR is a key target of V. dahliae for controlling and preventing Verticillium wilt in plants.
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Affiliation(s)
- Linxuan Li
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Tingting Zhu
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Yun Song
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, China.,National Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
| | - Xiumei Luo
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Li Feng
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Fengping Zhuo
- School of Life Sciences, Chongqing University, Chongqing, China.,School of Chemistry and Chemical Engineering, Chongqing University of Science and Technology, Chongqing, China
| | - Fuguang Li
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, China.,National Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
| | - Maozhi Ren
- School of Life Sciences, Chongqing University, Chongqing, China
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45
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Kumar P, Kundu D, Mondal AK, Nain V, Puria R. Inhibition of TOR signalling in lea1 mutant induces apoptosis in Saccharomyces cerevisiae. ANN MICROBIOL 2019. [DOI: 10.1007/s13213-018-1422-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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46
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Chao LH, Avruch J. Cryo-EM insight into the structure of MTOR complex 1 and its interactions with Rheb and substrates. F1000Res 2019; 8. [PMID: 30647914 PMCID: PMC6325617 DOI: 10.12688/f1000research.16109.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/18/2018] [Indexed: 12/31/2022] Open
Abstract
The mechanistic target of rapamycin (MTOR) is a giant protein kinase that, together with the accessory proteins Raptor and mLst8, forms a complex of over 1 MDa known as MTOR complex 1 (MTORC1). MTORC1, through its protein kinase activity, controls the accretion of cell mass through the regulation of gene transcription, mRNA translation, and protein turnover. MTORC1 is activated in an interdependent manner by insulin/growth factors and nutrients, especially amino acids, and is inhibited by stressors such as hypoxia and by the drug rapamycin. The action of insulin/growth factors converges on the small GTPase Rheb, which binds directly to the MTOR polypeptide in MTORC1 and, in its GTP-bound state, initiates kinase activation. Biochemical studies established that MTORC1 exists as a dimer of the MTOR/Raptor/mLst8 trimer, and progressive refinements in cryo-electron microscopy (cryo-EM) have enabled an increasingly clear picture of the architecture of MTORC1, culminating in a deep understanding of how MTORC1 interacts with and phosphorylates its best-known substrates-the eIF-4E binding protein/4E-BP, the p70 S6 kinase/S6K1B, and PRAS40/AKT1S1-and how this is inhibited by rapamycin. Most recently, Rheb-GTP has been shown to bind to MTORC1 in a cooperative manner at an allosteric site remote from the kinase domain that twists the latter into a catalytically competent configuration. Herein, we review the recent cryo-EM and associated biochemical studies of MTORC1 and seek to integrate these new results with the known physiology of MTORC1 regulation and signaling.
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Affiliation(s)
- Luke H Chao
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Joseph Avruch
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Medicine, Harvard Medical School, Boston, MA, USA
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47
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Boutouja F, Stiehm CM, Platta HW. mTOR: A Cellular Regulator Interface in Health and Disease. Cells 2019; 8:cells8010018. [PMID: 30609721 PMCID: PMC6356367 DOI: 10.3390/cells8010018] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 12/25/2018] [Accepted: 01/01/2019] [Indexed: 12/19/2022] Open
Abstract
The mechanistic target of Rapamycin (mTOR) is a ubiquitously-conserved serine/threonine kinase, which has a central function in integrating growth signals and orchestrating their physiologic effects on cellular level. mTOR is the core component of differently composed signaling complexes that differ in protein composition and molecular targets. Newly identified classes of mTOR inhibitors are being developed to block autoimmune diseases and transplant rejections but also to treat obesity, diabetes, and different types of cancer. Therefore, the selective and context-dependent inhibition of mTOR activity itself might come into the focus as molecular target to prevent severe diseases and possibly to extend life span. This review provides a general introduction to the molecular composition and physiologic function of mTOR complexes as part of the Special Issue “2018 Select Papers by Cells’ Editorial Board Members”.
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Affiliation(s)
- Fahd Boutouja
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Christian M Stiehm
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Harald W Platta
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44801 Bochum, Germany.
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48
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Takeuchi T, Benning C. Nitrogen-dependent coordination of cell cycle, quiescence and TAG accumulation in Chlamydomonas. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:292. [PMID: 31890020 PMCID: PMC6927116 DOI: 10.1186/s13068-019-1635-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 12/12/2019] [Indexed: 05/07/2023]
Abstract
Microalgae hold great promises as sustainable cellular factories for the production of alternative fuels, feeds, and biopharmaceuticals for human health. While the biorefinery approach for fuels along with the coproduction of high-value compounds with industrial, therapeutic, or nutraceutical applications have the potential to make algal biofuels more economically viable, a number of challenges continue to hamper algal production systems at all levels. One such hurdle includes the metabolic trade-off often observed between the increased yields of desired products, such as triacylglycerols (TAG), and the growth of an organism. Initial genetic engineering strategies to improve lipid productivity in microalgae, which focused on overproducing the enzymes involved in fatty acid and TAG biosynthesis or inactivating competing carbon (C) metabolism, have seen some successes albeit at the cost of often greatly reduced biomass. Emergent approaches that aim at modifying the dynamics of entire metabolic pathways by engineering of pertinent transcription factors or signaling networks appear to have successfully achieved a balance between growth and neutral lipid accumulation. However, the biological knowledge of key signaling networks and molecular components linking these two processes is still incomplete in photosynthetic eukaryotes, making it difficult to optimize metabolic engineering strategies for microalgae. Here, we focus on nitrogen (N) starvation of the model green microalga, Chlamydomonas reinhardtii, to present the current understanding of the nutrient-dependent switch between proliferation and quiescence, and the drastic reprogramming of metabolism that results in the storage of C compounds following N starvation. We discuss the potential components mediating the transcriptional repression of cell cycle genes and the establishment of quiescence in Chlamydomonas, and highlight the importance of signaling pathways such as those governed by the target of rapamycin (TOR) and sucrose nonfermenting-related (SnRK) kinases in the coordination of metabolic status with cellular growth. A better understanding of how the cell division cycle is regulated in response to nutrient scarcity and of the signaling pathways linking cellular growth to energy and lipid homeostasis, is essential to improve the prospects of biofuels and biomass production in microalgae.
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Affiliation(s)
- Tomomi Takeuchi
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
| | - Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
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49
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Therapeutic Use of mTOR Inhibitors in Renal Diseases: Advances, Drawbacks, and Challenges. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:3693625. [PMID: 30510618 PMCID: PMC6231362 DOI: 10.1155/2018/3693625] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 09/07/2018] [Accepted: 09/25/2018] [Indexed: 02/06/2023]
Abstract
The mammalian (or mechanistic) target of rapamycin (mTOR) pathway has a key role in the regulation of a variety of biological processes pivotal for cellular life, aging, and death. Impaired activity of mTOR complexes (mTORC1/mTORC2), particularly mTORC1 overactivation, has been implicated in a plethora of age-related disorders, including human renal diseases. Since the discovery of rapamycin (or sirolimus), more than four decades ago, advances in our understanding of how mTOR participates in renal physiological and pathological mechanisms have grown exponentially, due to both preclinical studies in animal models with genetic modification of some mTOR components as well as due to evidence coming from the clinical experience. The main clinical indication of rapamycin is as immunosuppressive therapy for the prevention of allograft rejection, namely, in renal transplantation. However, considering the central participation of mTOR in the pathogenesis of other renal disorders, the use of rapamycin and its analogs meanwhile developed (rapalogues) everolimus and temsirolimus has been viewed as a promising pharmacological strategy. This article critically reviews the use of mTOR inhibitors in renal diseases. Firstly, we briefly overview the mTOR components and signaling as well as the pharmacological armamentarium targeting the mTOR pathway currently available or in the research and development stages. Thereafter, we revisit the mTOR pathway in renal physiology to conclude with the advances, drawbacks, and challenges regarding the use of mTOR inhibitors, in a translational perspective, in four classes of renal diseases: kidney transplantation, polycystic kidney diseases, renal carcinomas, and diabetic nephropathy.
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50
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Decrease in plasma membrane tension triggers PtdIns(4,5)P 2 phase separation to inactivate TORC2. Nat Cell Biol 2018; 20:1043-1051. [PMID: 30154550 PMCID: PMC6237274 DOI: 10.1038/s41556-018-0150-z] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 06/21/2018] [Indexed: 02/06/2023]
Abstract
The target of rapamycin complex 2 (TORC2) plays a key role in maintaining the homeostasis of plasma membrane (PM) tension. TORC2 activation following increased PM tension involves redistribution of the Slm1 and 2 paralogues from PM invaginations known as eisosomes into membrane compartments containing TORC2. How Slm1/2 relocalization is triggered, and if/how this plays a role in TORC2 inactivation with decreased PM tension, is unknown. Using osmotic shocks and palmitoylcarnitine as orthogonal tools to manipulate PM tension, we demonstrate that decreased PM tension triggers spontaneous, energy-independent reorganization of pre-existing phosphatidylinositol-4,5-bisphosphate into discrete invaginated membrane domains, which cluster and inactivate TORC2. These results demonstrate that increased and decreased membrane tension are sensed through different mechanisms, highlighting a role for membrane lipid phase separation in mechanotransduction.
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