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Rossetti CL, Alves BL, Peçanha FLM, Franco AT, Nosé V, Carneiro EM, Lew J, Bernal-Mizrachi E, Werneck-de-Castro JP. Defining the In Vivo Role of mTORC1 in Thyrocytes by Studying the TSC2 Conditional Knockout Mouse Model. Thyroid 2024; 34:1047-1057. [PMID: 38661550 DOI: 10.1089/thy.2024.0053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Background: The thyroid gland is susceptible to abnormal epithelial cell growth, often resulting in thyroid dysfunction. The serine-threonine protein kinase mechanistic target of rapamycin (mTOR) regulates cellular metabolism, proliferation, and growth through two different protein complexes, mTORC1 and mTORC2. The PI3K-Akt-mTORC1 pathway's overactivity is well associated with heightened aggressiveness in thyroid cancer, but recent studies indicate the involvement of mTORC2 as well. Methods: To elucidate mTORC1's role in thyrocytes, we developed a novel mouse model with mTORC1 gain of function in thyrocytes by deleting tuberous sclerosis complex 2 (TSC2), an intracellular inhibitor of mTORC1. Results: The resulting TPO-TSC2KO mice exhibited a 70-80% reduction in TSC2 levels, leading to a sixfold increase in mTORC1 activity. Thyroid glands of both male and female TPO-TSC2KO mice displayed rapid enlargement and continued growth throughout life, with larger follicles and increased colloid and epithelium areas. We observed elevated thyrocyte proliferation as indicated by Ki67 staining and elevated cyclin D3 expression in the TPO-TSC2KO mice. mTORC1 activation resulted in a progressive downregulation of key genes involved in thyroid hormone biosynthesis, including thyroglobulin (Tg), thyroid peroxidase (Tpo), and sodium-iodide symporter (Nis), while Tff1, Pax8, and Mct8 mRNA levels remained unaffected. NIS protein expression was also diminished in TPO-TSC2KO mice. Treatment with the mTORC1 inhibitor rapamycin prevented thyroid mass expansion and restored the gene expression alterations in TPO-TSC2KO mice. Although total thyroxine (T4), total triiodothyronine (T3), and TSH plasma levels were normal at 2 months of age, a slight decrease in T4 and an increase in TSH levels were observed at 6 and 12 months of age while T3 remained similar in TPO-TSC2KO compared with littermate control mice. Conclusions: Our thyrocyte-specific mouse model reveals that mTORC1 activation inhibits thyroid hormone (TH) biosynthesis, suppresses thyrocyte gene expression, and promotes growth and proliferation.
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Affiliation(s)
- Camila Ludke Rossetti
- Division of Endocrinology, Diabetes and Metabolism, University of Miami, Miami, Florida, USA
| | - Bruna Lourençoni Alves
- Division of Endocrinology, Diabetes and Metabolism, University of Miami, Miami, Florida, USA
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas, Brazil
| | | | - Aime T Franco
- Division of Endocrinology and Diabetes, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Vania Nosé
- Massachusetts General Hospital, Harvard University, Boston, Massachusetts, USA
| | - Everardo Magalhaes Carneiro
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas, Brazil
| | - John Lew
- Department of Surgery, University of Miami, Miami, Florida, USA
- Miami VA Health Care System, Miami, Florida, USA
| | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Diabetes and Metabolism, University of Miami, Miami, Florida, USA
- Department of Surgery, University of Miami, Miami, Florida, USA
- Miami VA Health Care System, Miami, Florida, USA
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2
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Tabaka O, Lawal S, Del Rio Triana R, Hou M, Fraser A, Gallagher A, San Agustin Ruiz K, Marmarcz M, Dickinson M, Oliveira MM, Klann E, Shrestha P. Aberrant TSC-Rheb axis in Oxytocin receptor+ cells mediate stress-induced anxiety. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.25.600464. [PMID: 38979197 PMCID: PMC11230205 DOI: 10.1101/2024.06.25.600464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Stress is a major risk for the onset of several maladaptive processes including pathological anxiety, a diffuse state of heightened apprehension over anticipated threats1. Pathological anxiety is prevalent in up to 59% of patients with Tuberous Sclerosis complex (TSC)2, a neurodevelopmental disorder (NDD) caused by loss-of-function mutations in genes for Tuberin (Tsc2) and/or Hamartin (Tsc1) that together comprise the eponymous protein complex. Here, we generated cell type-specific heterozygous knockout of Tsc2 in cells expressing oxytocin receptor (OTRCs) to model pathological anxiety-like behaviors observed in TSC patient population. The stress of prolonged social isolation induces a sustained negative affective state that precipitates behavioral avoidance, often by aberrant oxytocin signaling in the limbic forebrain3,4. In response to social isolation, there were striking sex differences in stress susceptibility in conditional heterozygote mice when encountering situations of approach-avoidance conflict. Socially isolated male mutants exhibited behavioral avoidance in anxiogenic environments and sought more social interaction for buffering of stress. In contrast, female mutants developed resilience during social isolation and approached anxiogenic environments, while devaluing social interaction. Systemic and medial prefrontal cortex (mPFC)-specific inhibition of downstream effector of TSC, the integrated stress response (ISR), rescued behavioral approach toward anxiogenic environments and conspecifics in male and female mutant mice respectively. Further, we found that Tsc2 deletion in OTRCs leads to OTR-signaling elicited network suppression, i.e., hypofrontality, in male mPFC, which is relieved by inhibiting the ISR. Our findings present evidence in support of a sexually dimorphic role of prefrontal OTRCs in regulating emotional responses in anxiogenic environments, which goes awry in TSC. Our work has broader implications for developing effective treatments for subtypes of anxiety disorders that are characterized by cell-autonomous ISR and prefrontal network suppression.
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Affiliation(s)
- Olivia Tabaka
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
| | - Saheed Lawal
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
| | | | - Mian Hou
- Center for Neural Science, New York University, New York, NY 10003
| | - Alexandra Fraser
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
| | - Andrew Gallagher
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
| | | | - Maggie Marmarcz
- Center for Neural Science, New York University, New York, NY 10003
| | - Matthew Dickinson
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
| | | | - Eric Klann
- Center for Neural Science, New York University, New York, NY 10003
| | - Prerana Shrestha
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
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3
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Holmberg JC, Riley VA, Sokolov AM, Mukherjee S, Feliciano DM. Protocol for electroporating and isolating murine (sub)ventricular zone cells for single-nuclei omics. STAR Protoc 2024; 5:103095. [PMID: 38823010 PMCID: PMC11179414 DOI: 10.1016/j.xpro.2024.103095] [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: 01/25/2024] [Revised: 03/14/2024] [Accepted: 05/08/2024] [Indexed: 06/03/2024] Open
Abstract
In vivo genetic modification of neural stem cells is necessary to model the origins and pathogenesis of neurological disorders. Electroporation is a technique that applies a transient electrical field to direct charged molecules into living cells to genetically modify the mouse brain. Here, we provide a protocol to electroporate the neural stem cells surrounding the neonatal ventricles. We describe subsequent steps to isolate and prepare nuclei from the cells and their cellular progeny for single-nuclei omics. For complete details on the use and execution of this protocol, please refer to Riley et al.1.
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Affiliation(s)
- Jennie C Holmberg
- Department of Biological Sciences, Clemson University, Clemson, SC 29631, USA.
| | - Victoria A Riley
- Department of Biological Sciences, Clemson University, Clemson, SC 29631, USA
| | - Aidan M Sokolov
- Department of Biological Sciences, Clemson University, Clemson, SC 29631, USA
| | - Sulagna Mukherjee
- Department of Biological Sciences, Clemson University, Clemson, SC 29631, USA
| | - David M Feliciano
- Department of Biological Sciences, Clemson University, Clemson, SC 29631, USA; Center for Human Genetics, Clemson University, Greenwood, SC 29646, USA.
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4
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Lin SM, Rue R, Mukhitov AR, Goel A, Basil MC, Obraztsova K, Babu A, Crnkovic S, Ledwell OA, Ferguson LT, Planer JD, Nottingham AN, Vanka KS, Smith CJ, Cantu E, Kwapiszewska G, Morrisey EE, Evans JF, Krymskaya VP. Hyperactive mTORC1 in lung mesenchyme induces endothelial cell dysfunction and pulmonary vascular remodeling. J Clin Invest 2023; 134:e172116. [PMID: 38127441 PMCID: PMC10866655 DOI: 10.1172/jci172116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 12/20/2023] [Indexed: 12/23/2023] Open
Abstract
Lymphangioleiomyomatosis (LAM) is a progressive cystic lung disease caused by tuberous sclerosis complex 1/2 (TSC1/2) gene mutations in pulmonary mesenchymal cells, resulting in activation of the mechanistic target of rapamycin complex 1 (mTORC1). A subset of patients with LAM develop pulmonary vascular remodeling and pulmonary hypertension. Little, however, is known regarding how LAM cells communicate with endothelial cells (ECs) to trigger vascular remodeling. In end-stage LAM lung explants, we identified EC dysfunction characterized by increased EC proliferation and migration, defective angiogenesis, and dysmorphic endothelial tube network formation. To model LAM disease, we used an mTORC1 gain-of-function mouse model with a Tsc2 KO (Tsc2KO) specific to lung mesenchyme (Tbx4LME-Cre Tsc2fl/fl), similar to the mesenchyme-specific genetic alterations seen in human disease. As early as 8 weeks of age, ECs from mice exhibited marked transcriptomic changes despite an absence of morphological changes to the distal lung microvasculature. In contrast, 1-year-old Tbx4LME-Cre Tsc2fl/fl mice spontaneously developed pulmonary vascular remodeling with increased medial thickness. Single-cell RNA-Seq of 1-year-old mouse lung cells identified paracrine ligands originating from Tsc2KO mesenchyme, which can signal through receptors in arterial ECs. These ECs had transcriptionally altered genes including those in pathways associated with blood vessel remodeling. The proposed pathophysiologic mesenchymal ligand-EC receptor crosstalk highlights the importance of an altered mesenchymal cell/EC axis in LAM and other hyperactive mTORC1-driven diseases. Since ECs in patients with LAM and in Tbx4LME-Cre Tsc2fl/fl mice did not harbor TSC2 mutations, our study demonstrates that constitutively active mTORC1 lung mesenchymal cells orchestrated dysfunctional EC responses that contributed to pulmonary vascular remodeling.
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Affiliation(s)
- Susan M. Lin
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
- Lung Biology Institute, and
| | - Ryan Rue
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
| | - Alexander R. Mukhitov
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
| | - Akansha Goel
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
| | - Maria C. Basil
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
- Lung Biology Institute, and
- Penn Cardiovascular Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kseniya Obraztsova
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
| | | | - Slaven Crnkovic
- Division of Physiology, Medical University of Graz, Graz, Austria
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria
- Institute for Lung Health, Justus-Liebig University Giessen, Giessen, Germany
| | - Owen A. Ledwell
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
| | - Laura T. Ferguson
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
- Lung Biology Institute, and
| | - Joseph D. Planer
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
- Lung Biology Institute, and
| | - Ana N. Nottingham
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
- Lung Biology Institute, and
| | - Kanth Swaroop Vanka
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
| | - Carly J. Smith
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
| | - Edward Cantu
- Lung Biology Institute, and
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Grazyna Kwapiszewska
- Division of Physiology, Medical University of Graz, Graz, Austria
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria
- Institute for Lung Health, Justus-Liebig University Giessen, Giessen, Germany
| | - Edward E. Morrisey
- Lung Biology Institute, and
- Penn Cardiovascular Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jillian F. Evans
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
| | - Vera P. Krymskaya
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine
- Lung Biology Institute, and
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5
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Riley VA, Shankar V, Holmberg JC, Sokolov AM, Neckles VN, Williams K, Lyman R, Mackay TF, Feliciano DM. Tsc2 coordinates neuroprogenitor differentiation. iScience 2023; 26:108442. [PMID: 38107199 PMCID: PMC10724693 DOI: 10.1016/j.isci.2023.108442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 09/22/2023] [Accepted: 11/09/2023] [Indexed: 12/19/2023] Open
Abstract
Neural stem cells (NSCs) of the ventricular-subventricular zone (V-SVZ) generate numerous cell types. The uncoupling of mRNA transcript availability and translation occurs during the progression from stem to differentiated states. The mTORC1 kinase pathway acutely controls proteins that regulate mRNA translation. Inhibiting mTORC1 during differentiation is hypothesized to be critical for brain development since somatic mutations of mTORC1 regulators perturb brain architecture. Inactivating mutations of TSC1 or TSC2 genes cause tuberous sclerosis complex (TSC). TSC patients have growths near the striatum and ventricles. Here, it is demonstrated that V-SVZ NSC Tsc2 inactivation causes striatal hamartomas. Tsc2 removal altered translation factors, translatomes, and translational efficiency. Single nuclei RNA sequencing following in vivo loss of Tsc2 revealed changes in NSC activation states. The inability to decouple mRNA transcript availability and translation delayed differentiation leading to the retention of immature phenotypes in hamartomas. Taken together, Tsc2 is required for translational repression and differentiation.
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Affiliation(s)
- Victoria A. Riley
- Department of Biological Sciences, Clemson University, Clemson, SC, USA
| | - Vijay Shankar
- Department of Biochemistry and Genetics, Clemson University, Clemson, SC, USA
- Center for Human Genetics, Clemson University, Greenwood, SC, USA
| | | | - Aidan M. Sokolov
- Department of Biological Sciences, Clemson University, Clemson, SC, USA
| | | | - Kaitlyn Williams
- Clemson University Genomics and Bioinformatics Facility (CUGBF), Clemson University, Clemson, SC, USA
| | - Rachel Lyman
- Department of Biochemistry and Genetics, Clemson University, Clemson, SC, USA
- Center for Human Genetics, Clemson University, Greenwood, SC, USA
| | - Trudy F.C. Mackay
- Department of Biochemistry and Genetics, Clemson University, Clemson, SC, USA
- Center for Human Genetics, Clemson University, Greenwood, SC, USA
| | - David M. Feliciano
- Department of Biological Sciences, Clemson University, Clemson, SC, USA
- Center for Human Genetics, Clemson University, Greenwood, SC, USA
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6
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Fritsch SD, Sukhbaatar N, Gonzales K, Sahu A, Tran L, Vogel A, Mazic M, Wilson JL, Forisch S, Mayr H, Oberle R, Weiszmann J, Brenner M, Vanhoutte R, Hofmann M, Pirnes-Karhu S, Magnes C, Kühnast T, Weckwerth W, Bock C, Klavins K, Hengstschläger M, Moissl-Eichinger C, Schabbauer G, Egger G, Pirinen E, Verhelst SHL, Weichhart T. Metabolic support by macrophages sustains colonic epithelial homeostasis. Cell Metab 2023; 35:1931-1943.e8. [PMID: 37804836 DOI: 10.1016/j.cmet.2023.09.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 06/23/2023] [Accepted: 09/14/2023] [Indexed: 10/09/2023]
Abstract
The intestinal epithelium has a high turnover rate and constantly renews itself through proliferation of intestinal crypt cells, which depends on insufficiently characterized signals from the microenvironment. Here, we showed that colonic macrophages were located directly adjacent to epithelial crypt cells in mice, where they metabolically supported epithelial cell proliferation in an mTORC1-dependent manner. Specifically, deletion of tuberous sclerosis complex 2 (Tsc2) in macrophages activated mTORC1 signaling that protected against colitis-induced intestinal damage and induced the synthesis of the polyamines spermidine and spermine. Epithelial cells ingested these polyamines and rewired their cellular metabolism to optimize proliferation and defense. Notably, spermine directly stimulated proliferation of colon epithelial cells and colon organoids. Genetic interference with polyamine production in macrophages altered global polyamine levels in the colon and modified epithelial cell proliferation. Our results suggest that macrophages act as "commensals" that provide metabolic support to promote efficient self-renewal of the colon epithelium.
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Affiliation(s)
| | - Nyamdelger Sukhbaatar
- Center for Pathobiochemsitry & Genetics, Medical University of Vienna, Vienna, Austria
| | - Karine Gonzales
- Center for Pathobiochemsitry & Genetics, Medical University of Vienna, Vienna, Austria
| | - Alishan Sahu
- Center for Pathobiochemsitry & Genetics, Medical University of Vienna, Vienna, Austria
| | - Loan Tran
- Department of Pathology, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Institute Applied Diagnostics (LBI AD), Vienna, Austria
| | - Andrea Vogel
- Institute for Vascular Biology, Center for Physiology and Pharmacology, Medical University Vienna, Vienna, Austria; Christian Doppler Laboratory Arginine Metabolism in Rheumatoid Arthritis and Multiple Sclerosis, Vienna, Austria
| | - Mario Mazic
- Center for Pathobiochemsitry & Genetics, Medical University of Vienna, Vienna, Austria
| | - Jayne Louise Wilson
- Center for Pathobiochemsitry & Genetics, Medical University of Vienna, Vienna, Austria
| | - Stephan Forisch
- Center for Pathobiochemsitry & Genetics, Medical University of Vienna, Vienna, Austria
| | - Hannah Mayr
- Center for Pathobiochemsitry & Genetics, Medical University of Vienna, Vienna, Austria
| | - Raimund Oberle
- Center for Pathobiochemsitry & Genetics, Medical University of Vienna, Vienna, Austria
| | - Jakob Weiszmann
- Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria; Vienna Metabolomics Center (VIME), University of Vienna, Vienna, Austria
| | - Martin Brenner
- Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria; Department of Pharmaceutical Sciences/ Pharmacognosy, Faculty of Life Sciences, University of Vienna, Vienna, Austria; Vienna Metabolomics Center (VIME), University of Vienna, Vienna, Austria
| | - Roeland Vanhoutte
- Laboratory of Chemical Biology, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Melanie Hofmann
- Institute for Vascular Biology, Center for Physiology and Pharmacology, Medical University Vienna, Vienna, Austria; Christian Doppler Laboratory Arginine Metabolism in Rheumatoid Arthritis and Multiple Sclerosis, Vienna, Austria
| | - Sini Pirnes-Karhu
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Christoph Magnes
- HEALTH-Institute for Biomedicine and Health Sciences, Joanneum Research Forschungsgesellschaft mbH, Graz, Austria
| | - Torben Kühnast
- Diagnostic and Research Department of Microbiology, Hygiene and Environmental Medicine, Medical University of Graz, Graz, Austria
| | - Wolfram Weckwerth
- Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria; Vienna Metabolomics Center (VIME), University of Vienna, Vienna, Austria
| | - Christoph Bock
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Institute of Artificial Intelligence, Center for Medical Statistics, Informatics, and Intelligent Systems, Medical University of Vienna, Vienna, Austria
| | - Kristaps Klavins
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Markus Hengstschläger
- Center for Pathobiochemsitry & Genetics, Medical University of Vienna, Vienna, Austria
| | - Christine Moissl-Eichinger
- Diagnostic and Research Department of Microbiology, Hygiene and Environmental Medicine, Medical University of Graz, Graz, Austria
| | - Gernot Schabbauer
- Institute for Vascular Biology, Center for Physiology and Pharmacology, Medical University Vienna, Vienna, Austria; Christian Doppler Laboratory Arginine Metabolism in Rheumatoid Arthritis and Multiple Sclerosis, Vienna, Austria
| | - Gerda Egger
- Department of Pathology, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Institute Applied Diagnostics (LBI AD), Vienna, Austria
| | - Eija Pirinen
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Research Unit of Biomedicine and Internal Medicine, Faculty of Medicine, University of Oulu, Oulu, Finland; Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - Steven H L Verhelst
- Laboratory of Chemical Biology, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Thomas Weichhart
- Center for Pathobiochemsitry & Genetics, Medical University of Vienna, Vienna, Austria.
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7
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Bueno‐Beti C, Lim CX, Protonotarios A, Szabo PL, Westaby J, Mazic M, Sheppard MN, Behr E, Hamza O, Kiss A, Podesser BK, Hengstschläger M, Weichhart T, Asimaki A. An mTORC1-Dependent Mouse Model for Cardiac Sarcoidosis. J Am Heart Assoc 2023; 12:e030478. [PMID: 37750561 PMCID: PMC10727264 DOI: 10.1161/jaha.123.030478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/15/2023] [Indexed: 09/27/2023]
Abstract
Background Sarcoidosis is an inflammatory, granulomatous disease of unknown cause affecting multiple organs, including the heart. Untreated, unresolved granulomatous inflammation can lead to cardiac fibrosis, arrhythmias, and eventually heart failure. Here we characterize the cardiac phenotype of mice with chronic activation of mammalian target of rapamycin (mTOR) complex 1 signaling in myeloid cells known to cause spontaneous pulmonary sarcoid-like granulomas. Methods and Results The cardiac phenotype of mice with conditional deletion of the tuberous sclerosis 2 (TSC2) gene in CD11c+ cells (TSC2fl/flCD11c-Cre; termed TSC2KO) and controls (TSC2fl/fl) was determined by histological and immunological stains. Transthoracic echocardiography and invasive hemodynamic measurements were performed to assess myocardial function. TSC2KO animals were treated with either everolimus, an mTOR inhibitor, or Bay11-7082, a nuclear factor-kB inhibitor. Activation of mTOR signaling was evaluated on myocardial samples from sudden cardiac death victims with a postmortem diagnosis of cardiac sarcoidosis. Chronic activation of mTORC1 signaling in CD11c+ cells was sufficient to initiate progressive accumulation of granulomatous infiltrates in the heart, which was associated with increased fibrosis, impaired cardiac function, decreased plakoglobin expression, and abnormal connexin 43 distribution, a substrate for life-threatening arrhythmias. Mice treated with the mTOR inhibitor everolimus resolved granulomatous infiltrates, prevented fibrosis, and improved cardiac dysfunction. In line, activation of mTOR signaling in CD68+ macrophages was detected in the hearts of sudden cardiac death victims who suffered from cardiac sarcoidosis. Conclusions To our best knowledge this is the first animal model of cardiac sarcoidosis that recapitulates major pathological hallmarks of human disease. mTOR inhibition may be a therapeutic option for patients with cardiac sarcoidosis.
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Affiliation(s)
- Carlos Bueno‐Beti
- Clinical Cardiology Academic Group, Molecular and Clinical Research Science InstituteSt George’s University of LondonLondonUnited Kingdom
| | - Clarice X. Lim
- Center for Pathobiochemistry and GeneticsMedical University of ViennaViennaAustria
| | - Alexandros Protonotarios
- Institute of Cardiovascular Science, Clinical Science Research GroupUniversity College LondonLondonUnited Kingdom
| | - Petra Lujza Szabo
- Center for Biomedical ResearchMedical University of ViennaViennaAustria
| | - Joseph Westaby
- Clinical Cardiology Academic Group, Molecular and Clinical Research Science InstituteSt George’s University of LondonLondonUnited Kingdom
| | - Mario Mazic
- Center for Pathobiochemistry and GeneticsMedical University of ViennaViennaAustria
| | - Mary N. Sheppard
- Clinical Cardiology Academic Group, Molecular and Clinical Research Science InstituteSt George’s University of LondonLondonUnited Kingdom
| | - Elijah Behr
- Clinical Cardiology Academic Group, Molecular and Clinical Research Science InstituteSt George’s University of LondonLondonUnited Kingdom
| | - Ouafa Hamza
- Center for Biomedical ResearchMedical University of ViennaViennaAustria
| | - Attila Kiss
- Center for Biomedical ResearchMedical University of ViennaViennaAustria
| | - Bruno K. Podesser
- Center for Biomedical ResearchMedical University of ViennaViennaAustria
| | | | - Thomas Weichhart
- Center for Pathobiochemistry and GeneticsMedical University of ViennaViennaAustria
| | - Angeliki Asimaki
- Clinical Cardiology Academic Group, Molecular and Clinical Research Science InstituteSt George’s University of LondonLondonUnited Kingdom
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8
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Brazill JM, Shin D, Magee K, Majumdar A, Shen IR, Cavalli V, Scheller EL. Knockout of TSC2 in Nav1.8+ neurons predisposes to the onset of normal weight obesity. Mol Metab 2023; 68:101664. [PMID: 36586433 PMCID: PMC9841058 DOI: 10.1016/j.molmet.2022.101664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 12/22/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE Obesity and nutrient oversupply increase mammalian target of rapamycin (mTOR) signaling in multiple cell types and organs, contributing to the onset of insulin resistance and complications of metabolic disease. However, it remains unclear when and where mTOR activation mediates these effects, limiting options for therapeutic intervention. The objective of this study was to isolate the role of constitutive mTOR activation in Nav1.8-expressing peripheral neurons in the onset of diet-induced obesity, bone loss, and metabolic disease. METHODS In humans, loss of function mutations in tuberous sclerosis complex 2 (TSC2) lead to maximal constitutive activation of mTOR. To mirror this in mice, we bred Nav1.8-Cre with TSC2fl/fl animals to conditionally delete TSC2 in Nav1.8-expressing neurons. Male and female mice were studied from 4- to 34-weeks of age and a subset of animals were fed a high-fat diet (HFD) for 24-weeks. Assays of metabolism, body composition, bone morphology, and behavior were performed. RESULTS By lineage tracing, Nav1.8-Cre targeted peripheral sensory neurons, a subpopulation of postganglionic sympathetics, and several regions of the brain. Conditional knockout of TSC2 in Nav1.8-expressing neurons (Nav1.8-TSC2KO) selectively upregulated neuronal mTORC1 signaling. Male, but not female, Nav1.8-TSC2KO mice had a 4-10% decrease in body size at baseline. When challenged with HFD, both male and female Nav1.8-TSC2KO mice resisted diet-induced gains in body mass. However, this did not protect against HFD-induced metabolic dysfunction and bone loss. In addition, despite not gaining weight, Nav1.8-TSC2KO mice fed HFD still developed high body fat, a unique phenotype previously referred to as 'normal weight obesity'. Nav1.8-TSC2KO mice also had signs of chronic itch, mild increases in anxiety-like behavior, and sex-specific alterations in HFD-induced fat distribution that led to enhanced visceral obesity in males and preferential deposition of subcutaneous fat in females. CONCLUSIONS Knockout of TSC2 in Nav1.8+ neurons increases itch- and anxiety-like behaviors and substantially modifies fat storage and metabolic responses to HFD. Though this prevents HFD-induced weight gain, it masks depot-specific fat expansion and persistent detrimental effects on metabolic health and peripheral organs such as bone, mimicking the 'normal weight obesity' phenotype that is of growing concern. This supports a mechanism by which increased neuronal mTOR signaling can predispose to altered adipose tissue distribution, adipose tissue expansion, impaired peripheral metabolism, and detrimental changes to skeletal health with HFD - despite resistance to weight gain.
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Affiliation(s)
- Jennifer M Brazill
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, Saint Louis, MO, USA.
| | - David Shin
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, Saint Louis, MO, USA.
| | - Kristann Magee
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, Saint Louis, MO, USA.
| | - Anurag Majumdar
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, Saint Louis, MO, USA.
| | - Ivana R Shen
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, Saint Louis, MO, USA.
| | - Valeria Cavalli
- Department of Neuroscience, Washington University, Saint Louis, MO, USA; Center of Regenerative Medicine, Washington University School of Medicine, Saint Louis, MO, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, Saint Louis, MO, USA.
| | - Erica L Scheller
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, Saint Louis, MO, USA; Center of Regenerative Medicine, Washington University School of Medicine, Saint Louis, MO, USA; Department of Cell Biology and Physiology, Washington University, Saint Louis, MO, USA; Department of Biomedical Engineering, Washington University, Saint Louis, MO, USA.
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9
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Barone S, Brooks M, Zahedi K, Holliday LS, Bissler J, Yu JJ, Soleimani M. Identification of an Electrogenic 2Cl -/H + Exchanger, ClC5, as a Chloride-Secreting Transporter Candidate in Kidney Cyst Epithelium in Tuberous Sclerosis. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:191-200. [PMID: 36336066 PMCID: PMC9926528 DOI: 10.1016/j.ajpath.2022.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/23/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022]
Abstract
Kidney cyst expansion in tuberous sclerosis complex (TSC) or polycystic kidney disease (PKD) requires active secretion of chloride (Cl-) into the cyst lumen. In PKD, Cl- secretion is primarily mediated via the cystic fibrosis transmembrane conductance regulator (CFTR) in principal cells. Kidney cystogenesis in TSC is predominantly composed of type A intercalated cells, which do not exhibit noticeable expression of CFTR. The identity of the Cl--secreting molecule(s) in TSC cyst epithelia remains speculative. RNA-sequencing analysis results were used to examine the expression of FOXi1, the chief regulator of acid base transporters in intercalated cells, along with localization of Cl- channel 5 (ClC5), in various models of TSC. Results from Tsc2+/- mice showed that the expansion of kidney cysts corresponded to the induction of Foxi1 and correlated with the appearance of ClC5 and H+-ATPase on the apical membrane of cyst epithelia. In various mouse models of TSC, Foxi1 was robustly induced in the kidney, and ClC5 and H+-ATPase were expressed on the apical membrane of cyst epithelia. Expression of ClC5 was also detected on the apical membrane of cyst epithelia in humans with TSC but was absent in humans with autosomal dominant PKD or in a mouse model of PKD. These results indicate that ClC5 is expressed on the apical membrane of cyst epithelia and is a likely candidate mediating Cl- secretion into the kidney cyst lumen in TSC.
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Affiliation(s)
- Sharon Barone
- Research Services, Veterans Health Care Medical Center, Albuquerque, New Mexico; Department of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Marybeth Brooks
- Research Services, Veterans Health Care Medical Center, Albuquerque, New Mexico; Department of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Kamyar Zahedi
- Research Services, Veterans Health Care Medical Center, Albuquerque, New Mexico; Department of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | | | - John Bissler
- Department of Pediatrics, University of Tennessee Health Science Center and Le Bonheur Children's Hospital, Memphis, Tennessee; Department of Pediatrics, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Jane J Yu
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Manoocher Soleimani
- Research Services, Veterans Health Care Medical Center, Albuquerque, New Mexico; Department of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico.
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10
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Huang Z, You X, Chen L, Du Y, Brodeur K, Jee H, Wang Q, Linder G, Darbousset R, Cunin P, Chang MH, Wactor A, Wauford BM, Todd MJC, Wei K, Li Y, Levescot A, Iwakura Y, Pascual V, Baldwin NE, Quartier P, Li T, Gianatasio MT, Hasserjian RP, Henderson LA, Sykes DB, Mellins ED, Canna SW, Charles JF, Nigrovic PA, Lee PY. mTORC1 links pathology in experimental models of Still's disease and macrophage activation syndrome. Nat Commun 2022; 13:6915. [PMID: 36443301 PMCID: PMC9705324 DOI: 10.1038/s41467-022-34480-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 10/26/2022] [Indexed: 11/29/2022] Open
Abstract
Still's disease is a severe inflammatory syndrome characterized by fever, skin rash and arthritis affecting children and adults. Patients with Still's disease may also develop macrophage activation syndrome, a potentially fatal complication of immune dysregulation resulting in cytokine storm. Here we show that mTORC1 (mechanistic target of rapamycin complex 1) underpins the pathology of Still's disease and macrophage activation syndrome. Single-cell RNA sequencing in a murine model of Still's disease shows preferential activation of mTORC1 in monocytes; both mTOR inhibition and monocyte depletion attenuate disease severity. Transcriptomic data from patients with Still's disease suggest decreased expression of the mTORC1 inhibitors TSC1/TSC2 and an mTORC1 gene signature that strongly correlates with disease activity and treatment response. Unrestricted activation of mTORC1 by Tsc2 deletion in mice is sufficient to trigger a Still's disease-like syndrome, including both inflammatory arthritis and macrophage activation syndrome with hemophagocytosis, a cellular manifestation that is reproduced in human monocytes by CRISPR/Cas-mediated deletion of TSC2. Consistent with this observation, hemophagocytic histiocytes from patients with macrophage activation syndrome display prominent mTORC1 activity. Our study suggests a mechanistic link of mTORC1 to inflammation that connects the pathogenesis of Still's disease and macrophage activation syndrome.
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Affiliation(s)
- Zhengping Huang
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA ,grid.38142.3c000000041936754XDivision of Rheumatology, Inflammation, and Immunity, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA USA ,grid.413405.70000 0004 1808 0686Department of Rheumatology and Immunology, Guangdong Second Provincial General Hospital, Guangzhou, China
| | - Xiaomeng You
- grid.38142.3c000000041936754XDepartment of Orthopaedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA USA
| | - Liang Chen
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - Yan Du
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA ,grid.412465.0Department of Rheumatology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Kailey Brodeur
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - Hyuk Jee
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - Qiang Wang
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - Grace Linder
- grid.239552.a0000 0001 0680 8770Blood Bank and Transfusion Medicine Division, Children’s Hospital of Philadelphia, Philadelphia, PA USA
| | - Roxane Darbousset
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - Pierre Cunin
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - Margaret H. Chang
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - Alexandra Wactor
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - Brian M. Wauford
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - Marc J. C. Todd
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - Kevin Wei
- grid.38142.3c000000041936754XDivision of Rheumatology, Inflammation, and Immunity, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA USA
| | - Ying Li
- grid.38142.3c000000041936754XDivision of Rheumatology, Inflammation, and Immunity, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA USA
| | - Anais Levescot
- grid.462336.6Université Paris Cité, Institut Imagine, INSERM UMR1163, Laboratory Intestinal Immunity, Paris, France
| | - Yoichiro Iwakura
- grid.143643.70000 0001 0660 6861Centre for Animal Disease Models, Research Institute for Biomedical Sciences, Tokyo University of Science, Chiba, Japan
| | - Virginia Pascual
- grid.5386.8000000041936877XDepartment of Pediatrics and Drukier Institute for Children’s Health, Weill Cornell Medicine, New York, NY USA
| | - Nicole E. Baldwin
- grid.486749.00000 0004 4685 2620Baylor Scott & White Research Institute, Dallas, TX USA
| | - Pierre Quartier
- grid.5842.b0000 0001 2171 2558Pediatric Immunology, Hematology and Rheumatology Unit, Necker-Enfants Malades Hospital, Assistance Publique-Hopitaux de Paris, Universite de Paris, Paris, France
| | - Tianwang Li
- grid.413405.70000 0004 1808 0686Department of Rheumatology and Immunology, Guangdong Second Provincial General Hospital, Guangzhou, China
| | - Maria T. Gianatasio
- grid.416636.00000 0004 0460 4960Mass General Brigham Healthcare Center - Salem Hospital, Salem, MA USA
| | - Robert P. Hasserjian
- grid.38142.3c000000041936754XDepartment of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA
| | - Lauren A. Henderson
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
| | - David B. Sykes
- grid.32224.350000 0004 0386 9924Center for Regenerative Medicine, Massachusetts General Hospital, Boston, USA
| | - Elizabeth D. Mellins
- grid.168010.e0000000419368956Department of Pediatrics, Program in Immunology, Stanford University, Stanford, CA USA
| | - Scott W. Canna
- grid.239552.a0000 0001 0680 8770Division of Rheumatology, Children’s Hospital of Philadelphia, Philadelphia, PA USA
| | - Julia F. Charles
- grid.38142.3c000000041936754XDivision of Rheumatology, Inflammation, and Immunity, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA USA ,grid.38142.3c000000041936754XDepartment of Orthopaedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA USA
| | - Peter A. Nigrovic
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA ,grid.38142.3c000000041936754XDivision of Rheumatology, Inflammation, and Immunity, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA USA
| | - Pui Y. Lee
- grid.38142.3c000000041936754XDivision of Immunology, Boston Children’s Hospital, Harvard Medical School, Boston, MA USA
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11
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Bernard C, Exposito-Alonso D, Selten M, Sanalidou S, Hanusz-Godoy A, Aguilera A, Hamid F, Oozeer F, Maeso P, Allison L, Russell M, Fleck RA, Rico B, Marín O. Cortical wiring by synapse type-specific control of local protein synthesis. Science 2022; 378:eabm7466. [PMID: 36423280 DOI: 10.1126/science.abm7466] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
Neurons use local protein synthesis to support their morphological complexity, which requires independent control across multiple subcellular compartments up to the level of individual synapses. We identify a signaling pathway that regulates the local synthesis of proteins required to form excitatory synapses on parvalbumin-expressing (PV+) interneurons in the mouse cerebral cortex. This process involves regulation of the TSC subunit 2 (Tsc2) by the Erb-B2 receptor tyrosine kinase 4 (ErbB4), which enables local control of messenger RNA {mRNA} translation in a cell type-specific and synapse type-specific manner. Ribosome-associated mRNA profiling reveals a molecular program of synaptic proteins downstream of ErbB4 signaling required to form excitatory inputs on PV+ interneurons. Thus, specific connections use local protein synthesis to control synapse formation in the nervous system.
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Affiliation(s)
- Clémence Bernard
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - David Exposito-Alonso
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Martijn Selten
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Stella Sanalidou
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Alicia Hanusz-Godoy
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Alfonso Aguilera
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Fursham Hamid
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Fazal Oozeer
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Patricia Maeso
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Leanne Allison
- Centre for Ultrastructural Imaging, King's College London, London SE1 1UL, UK
| | - Matthew Russell
- Centre for Ultrastructural Imaging, King's College London, London SE1 1UL, UK
| | - Roland A Fleck
- Centre for Ultrastructural Imaging, King's College London, London SE1 1UL, UK
| | - Beatriz Rico
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Oscar Marín
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
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12
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Saré RM, Torossian A, Loutaev I, Smith CB. Confirmation of Decreased Rates of Cerebral Protein Synthesis In Vivo in a Mouse Model of Tuberous Sclerosis Complex. eNeuro 2022; 9:ENEURO.0480-21.2022. [PMID: 35851298 PMCID: PMC9347307 DOI: 10.1523/eneuro.0480-21.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 04/29/2022] [Accepted: 05/23/2022] [Indexed: 11/21/2022] Open
Abstract
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that results in intellectual disability and, in ∼50% of patients, autism spectrum disorder. The protein products that are altered in TSC (TSC1 and TSC2) form a complex to inhibit the mammalian target of rapamycin [mTOR; mTOR complex 1 (mTORC1)] pathway. This pathway has been shown to affect the process of mRNA translation through its action on ribosomal protein S6 and 4-elongation binding protein 1. It is thought that mutations in the TSC proteins lead to upregulation of the mTORC1 pathway and consequently an increase in protein synthesis. Unexpectedly, our previous study of a mouse model of TSC (Tsc2Djk +/) demonstrated decreased in vivo rates of protein synthesis throughout the brain. In the present study, we confirm those results in another Tsc2+/- mouse model, one with a different mutation locus and on a mixed background (Tsc2Mjg +/-). We also examine mTORC1 signaling and possible effects of prior isoflurane anesthesia. Because measurements of protein synthesis rates in vivo require surgical preparation of the animal and anesthesia, we examine mTORC1 signaling pathways both under baseline conditions and following recovery from anesthesia. Our results demonstrate regionally selective effects of prior anesthesia. Overall, our results in both in vivo models suggest differences to the central hypothesis regarding TSC and show the importance of studying protein synthesis in vivo Significance StatementProtein synthesis is an important process for brain function. In the disorder, tuberous sclerosis complex (TSC), the inhibition of the mammalian target of rapamycin (mTOR) pathway is reduced and this is thought to lead to excessive protein synthesis. Most studies of protein synthesis in models of TSC have been conducted in vitro We report here confirmation of our previous in vivo study showing decreased brain protein synthesis rates in a second mouse model of TSC, results counter to the central hypothesis regarding TSC. We also explore the possible influence of prior isoflurane exposure on signaling pathways involved in regulation of protein synthesis. This study highlights a novel aspect of TSC and the importance of studying cellular processes in vivo.
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Affiliation(s)
- Rachel Michelle Saré
- Department of Health and Human Services, Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20814
| | - Anita Torossian
- Department of Health and Human Services, Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20814
| | - Inna Loutaev
- Department of Health and Human Services, Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20814
| | - Carolyn Beebe Smith
- Department of Health and Human Services, Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20814
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13
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Wang Y, Punzo C, Ash JD, Lobanova ES. Tsc2 knockout counteracts ubiquitin-proteasome system insufficiency and delays photoreceptor loss in retinitis pigmentosa. Proc Natl Acad Sci U S A 2022; 119:e2118479119. [PMID: 35275792 PMCID: PMC8931319 DOI: 10.1073/pnas.2118479119] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 01/12/2022] [Indexed: 01/18/2023] Open
Abstract
SignificanceStudies in multiple experimental systems have demonstrated that an increase in proteolytic capacity of post-mitotic cells improves cellular resistance to a variety of stressors, delays cellular aging and senescence. Therefore, approaches to increase the ability of cells to degrade misfolded proteins could potentially be applied to the treatment of a broad spectrum of human disorders. An example would be retinal degenerations, which cause irreversible loss of vision and are linked to impaired protein degradation. This study suggests that chronic activation of the mammalian target of rapamycin complex 1 (mTORC1) pathway in degenerating photoreceptor neurons could stimulate the degradation of ubiquitinated proteins and enhance proteasomal activity through phosphorylation.
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Affiliation(s)
- Yixiao Wang
- Department of Ophthalmology, University of Florida, Gainesville, FL 32610
| | - Claudio Punzo
- Department of Ophthalmology and Visual Sciences, University of Massachusetts Medical School, Worcester, MA 01655
| | - John D. Ash
- Department of Ophthalmology, University of Florida, Gainesville, FL 32610
| | - Ekaterina S. Lobanova
- Department of Ophthalmology, University of Florida, Gainesville, FL 32610
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610
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14
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Terry BK, Park R, Cho SH, Crino PB, Kim S. Abnormal activation of Yap/Taz contributes to the pathogenesis of tuberous sclerosis complex. Hum Mol Genet 2022; 31:1979-1996. [PMID: 34999833 PMCID: PMC9239747 DOI: 10.1093/hmg/ddab374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 10/31/2021] [Accepted: 12/27/2021] [Indexed: 01/09/2023] Open
Abstract
The multi-systemic genetic disorder tuberous sclerosis complex (TSC) impacts multiple neurodevelopmental processes including neuronal morphogenesis, neuronal migration, myelination and gliogenesis. These alterations contribute to the development of cerebral cortex abnormalities and malformations. Although TSC is caused by mTORC1 hyperactivation, cognitive and behavioral impairments are not improved through mTORC1 targeting, making the study of the downstream effectors of this complex important for understanding the mechanisms underlying TSC. As mTORC1 has been shown to promote the activity of the transcriptional co-activator Yap, we hypothesized that altered Yap/Taz signaling contributes to the pathogenesis of TSC. We first observed that the levels of Yap/Taz are increased in human cortical tuber samples and in embryonic cortices of Tsc2 conditional knockout (cKO) mice. Next, to determine how abnormal upregulation of Yap/Taz impacts the neuropathology of TSC, we deleted Yap/Taz in Tsc2 cKO mice. Importantly, Yap/Taz/Tsc2 triple conditional knockout (tcKO) animals show reduced cortical thickness and cortical neuron cell size, despite the persistence of high mTORC1 activity, suggesting that Yap/Taz play a downstream role in cytomegaly. Furthermore, Yap/Taz/Tsc2 tcKO significantly restored cortical and hippocampal lamination defects and reduced hippocampal heterotopia formation. Finally, the loss of Yap/Taz increased the distribution of myelin basic protein in Tsc2 cKO animals, consistent with an improvement in myelination. Overall, our results indicate that targeting Yap/Taz lessens the severity of neuropathology in a TSC animal model. This study is the first to implicate Yap/Taz as contributors to cortical pathogenesis in TSC and therefore as potential novel targets in the treatment of this disorder.
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Affiliation(s)
- Bethany K Terry
- Department of Neural Sciences, Lewis Katz School of Medicine, Shriners Hospitals Pediatrics Research Center, Temple University, Philadelphia, PA 19140, USA,Biomedical Sciences Graduate Program, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Raehee Park
- Department of Neural Sciences, Lewis Katz School of Medicine, Shriners Hospitals Pediatrics Research Center, Temple University, Philadelphia, PA 19140, USA
| | - Seo-Hee Cho
- Department of Medicine, Sidney Kimmel Medical College, Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Peter B Crino
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Seonhee Kim
- To whom correspondence should be addressed. Tel: 215-926-9360; Fax: 215-926-9325;
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15
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Shroff UN, Gyarmati G, Izuhara A, Deepak S, Peti-Peterdi J. A new view of macula densa cell protein synthesis. Am J Physiol Renal Physiol 2021; 321:F689-F704. [PMID: 34693742 PMCID: PMC8714974 DOI: 10.1152/ajprenal.00222.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 10/12/2021] [Accepted: 10/15/2021] [Indexed: 11/22/2022] Open
Abstract
Macula densa (MD) cells, a chief sensory cell type in the nephron, are endowed with unique microanatomic features including a high density of protein synthetic organelles and secretory vesicles in basal cell processes ("maculapodia") that suggest a so far unknown high rate of MD protein synthesis. This study aimed to explore the rate and regulation of MD protein synthesis and their effects on glomerular function using novel transgenic mouse models, newly established fluorescence cell biology techniques, and intravital microscopy. Sox2-tdTomato kidney tissue sections and an O-propargyl puromycin incorporation-based fluorescence imaging assay showed that MD cells have the highest level of protein synthesis within the kidney cortex followed by intercalated cells and podocytes. Genetic gain of function of mammalian target of rapamycin (mTOR) signaling specifically in MD cells (in MD-mTORgof mice) or their physiological activation by low-salt diet resulted in further significant increases in the synthesis of MD proteins. Specifically, these included both classic and recently identified MD-specific proteins such as cyclooxygenase 2, microsomal prostaglandin E2 synthase 1, and pappalysin 2. Intravital imaging of the kidney using multiphoton microscopy showed significant increases in afferent and efferent arteriole and glomerular capillary diameters and blood flow in MD-mTORgof mice coupled with an elevated glomerular filtration rate. The presently identified high rate of MD protein synthesis that is regulated by mTOR signaling is a novel component of the physiological activation and glomerular hemodynamic regulatory functions of MD cells that remains to be fully characterized.NEW & NOTEWORTHY This study discovered the high rate of protein synthesis in macula densa (MD) cells by applying direct imaging techniques with single cell resolution. Physiological activation and mammalian target of rapamycin signaling played important regulatory roles in this process. This new feature is a novel component of the tubuloglomerular cross talk and glomerular hemodynamic regulatory functions of MD cells. Future work is needed to elucidate the nature and (patho)physiological role of the specific proteins synthesized by MD cells.
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Affiliation(s)
- Urvi Nikhil Shroff
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California
| | - Georgina Gyarmati
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California
| | - Audrey Izuhara
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California
| | - Sachin Deepak
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California
- Department of Medicine, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California
| | - János Peti-Peterdi
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California
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16
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Braun C, Katholnig K, Kaltenecker C, Linke M, Sukhbaatar N, Hengstschläger M, Weichhart T. p38 regulates the tumor suppressor PDCD4 via the TSC-mTORC1 pathway. Cell Stress 2021; 5:176-182. [PMID: 34917890 PMCID: PMC8645265 DOI: 10.15698/cst2021.12.260] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 11/08/2021] [Accepted: 11/12/2021] [Indexed: 11/21/2022] Open
Abstract
Programmed cell death protein 4 (PDCD4) exerts critical functions as tumor suppressor and in immune cells to regulate inflammatory processes. The phosphoinositide 3-kinase (PI3K) promotes degradation of PDCD4 via mammalian target of rapamycin complex 1 (mTORC1). However, additional pathways that may regulate PDCD4 expression are largely ill-defined. In this study, we have found that activation of the mitogen-activated protein kinase p38 promoted degradation of PDCD4 in macrophages and fibroblasts. Mechanistically, we identified a pathway from p38 and its substrate MAP kinase-activated protein kinase 2 (MK2) to the tuberous sclerosis complex (TSC) to regulate mTORC1-dependent degradation of PDCD4. Moreover, we provide evidence that TSC1 and TSC2 regulate PDCD4 expression via an additional mechanism independent of mTORC1. These novel data extend our knowledge of how PDCD4 expression is regulated by stress- and nutrient-sensing pathways.
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Affiliation(s)
- Clarissa Braun
- Center of Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria
- Clinical Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Karl Katholnig
- Center of Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria
| | - Christopher Kaltenecker
- Department of Internal Medicine III, Division of Nephrology and Dialysis, Medical University of Vienna, Vienna, Austria
| | - Monika Linke
- Center of Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria
| | - Nyamdelger Sukhbaatar
- Center of Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria
| | - Markus Hengstschläger
- Center of Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria
| | - Thomas Weichhart
- Center of Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria
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17
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Tiu GC, Kerr CH, Forester CM, Krishnarao PS, Rosenblatt HD, Raj N, Lantz TC, Zhulyn O, Bowen ME, Shokat L, Attardi LD, Ruggero D, Barna M. A p53-dependent translational program directs tissue-selective phenotypes in a model of ribosomopathies. Dev Cell 2021; 56:2089-2102.e11. [PMID: 34242585 PMCID: PMC8319123 DOI: 10.1016/j.devcel.2021.06.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 03/26/2021] [Accepted: 06/11/2021] [Indexed: 12/13/2022]
Abstract
In ribosomopathies, perturbed expression of ribosome components leads to tissue-specific phenotypes. What accounts for such tissue-selective manifestations as a result of mutations in the ribosome, a ubiquitous cellular machine, has remained a mystery. Combining mouse genetics and in vivo ribosome profiling, we observe limb-patterning phenotypes in ribosomal protein (RP) haploinsufficient embryos, and we uncover selective translational changes of transcripts that controlling limb development. Surprisingly, both loss of p53, which is activated by RP haploinsufficiency, and augmented protein synthesis rescue these phenotypes. These findings are explained by the finding that p53 functions as a master regulator of protein synthesis, at least in part, through transcriptional activation of 4E-BP1. 4E-BP1, a key translational regulator, in turn, facilitates selective changes in the translatome downstream of p53, and this thereby explains how RP haploinsufficiency may elicit specificity to gene expression. These results provide an integrative model to help understand how in vivo tissue-specific phenotypes emerge in ribosomopathies.
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Affiliation(s)
- Gerald C Tiu
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA; Stanford Medical Scientist Training Program, Stanford University, Stanford, CA 94305, USA
| | - Craig H Kerr
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Craig M Forester
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA; Division of Pediatric Allergy, Immunology and Bone Marrow Transplantation, University of California, San Francisco, San Francisco, CA 94143, USA; Children's Hospital Colorado, Division of Pediatric Hematology/Oncology/Bone Marrow Transplant, Colorado, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Pallavi S Krishnarao
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Hannah D Rosenblatt
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Nitin Raj
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Travis C Lantz
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Olena Zhulyn
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Margot E Bowen
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Leila Shokat
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Laura D Attardi
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Davide Ruggero
- Department of Urology, University of California, San Francisco, San Francisco, CA 94143, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA.
| | - Maria Barna
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA.
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18
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HK2 Mediated Glycolytic Metabolism in Mouse Photoreceptors Is Not Required to Cause Late Stage Age-Related Macular Degeneration-Like Pathologies. Biomolecules 2021; 11:biom11060871. [PMID: 34208233 PMCID: PMC8230848 DOI: 10.3390/biom11060871] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/01/2021] [Accepted: 06/09/2021] [Indexed: 12/12/2022] Open
Abstract
Age-related macular degeneration (AMD) is a multifactorial disease of unclear etiology. We previously proposed that metabolic adaptations in photoreceptors (PRs) play a role in disease progression. We mimicked these metabolic adaptations in mouse PRs through deletion of the tuberous sclerosis complex (TSC) protein TSC1. Here, we confirm our previous findings by deletion of the other complex protein, namely TSC2, in rod photoreceptors. Similar to deletion of Tsc1, mice with deletion of Tsc2 in rods develop AMD-like pathologies, including accumulation of apolipoproteins, migration of microglia, geographic atrophy, and neovascular pathologies. Subtle differences between the two mouse models, such as a significant increase in microglia activation with loss of Tsc2, were seen as well. To investigate the role of altered glucose metabolism in disease pathogenesis, we generated mice with simulation deletions of Tsc2 and hexokinase-2 (Hk2) in rods. Although retinal lactate levels returned to normal in mice with Tsc2-Hk2 deletion, AMD-like pathologies still developed. The data suggest that the metabolic adaptations in PRs that cause AMD-like pathologies are independent of HK2-mediated aerobic glycolysis.
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19
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Davogustto GE, Salazar RL, Vasquez HG, Karlstaedt A, Dillon WP, Guthrie PH, Martin JR, Vitrac H, De La Guardia G, Vela D, Ribas-Latre A, Baumgartner C, Eckel-Mahan K, Taegtmeyer H. Metabolic remodeling precedes mTORC1-mediated cardiac hypertrophy. J Mol Cell Cardiol 2021; 158:115-127. [PMID: 34081952 DOI: 10.1016/j.yjmcc.2021.05.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 05/21/2021] [Accepted: 05/26/2021] [Indexed: 11/17/2022]
Abstract
RATIONALE The nutrient sensing mechanistic target of rapamycin complex 1 (mTORC1) and its primary inhibitor, tuberin (TSC2), are cues for the development of cardiac hypertrophy. The phenotype of mTORC1 induced hypertrophy is unknown. OBJECTIVE To examine the impact of sustained mTORC1 activation on metabolism, function, and structure of the adult heart. METHODS AND RESULTS We developed a mouse model of inducible, cardiac-specific sustained mTORC1 activation (mTORC1iSA) through deletion of Tsc2. Prior to hypertrophy, rates of glucose uptake and oxidation, as well as protein and enzymatic activity of glucose 6-phosphate isomerase (GPI) were decreased, while intracellular levels of glucose 6-phosphate (G6P) were increased. Subsequently, hypertrophy developed. Transcript levels of the fetal gene program and pathways of exercise-induced hypertrophy increased, while hypertrophy did not progress to heart failure. We therefore examined the hearts of wild-type mice subjected to voluntary physical activity and observed early changes in GPI, followed by hypertrophy. Rapamycin prevented these changes in both models. CONCLUSION Activation of mTORC1 in the adult heart triggers the development of a non-specific form of hypertrophy which is preceded by changes in cardiac glucose metabolism.
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Affiliation(s)
- Giovanni E Davogustto
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Rebecca L Salazar
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Hernan G Vasquez
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Anja Karlstaedt
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - William P Dillon
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Patrick H Guthrie
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Joseph R Martin
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, USA
| | | | - Gina De La Guardia
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Deborah Vela
- Cardiovascular Pathology Research Laboratory, Texas Heart Institute at CHI St. Luke's Health, and the Department of Pathology and Laboratory Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Aleix Ribas-Latre
- Center for Metabolic and Degenerative Diseases, Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Corrine Baumgartner
- Center for Metabolic and Degenerative Diseases, Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Kristin Eckel-Mahan
- Center for Metabolic and Degenerative Diseases, Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Heinrich Taegtmeyer
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, USA.
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20
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Bozadjieva Kramer N, Lubaczeuski C, Blandino-Rosano M, Barker G, Gittes GK, Caicedo A, Bernal-Mizrachi E. Glucagon Resistance and Decreased Susceptibility to Diabetes in a Model of Chronic Hyperglucagonemia. Diabetes 2021; 70:477-491. [PMID: 33239450 PMCID: PMC7881862 DOI: 10.2337/db20-0440] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 11/18/2020] [Indexed: 02/07/2023]
Abstract
Elevation of glucagon levels and increase in α-cell mass are associated with states of hyperglycemia in diabetes. Our previous studies have highlighted the role of nutrient signaling via mTOR complex 1 (mTORC1) regulation that controls glucagon secretion and α-cell mass. In the current studies we investigated the effects of activation of nutrient signaling by conditional deletion of the mTORC1 inhibitor, TSC2, in α-cells (αTSC2KO). We showed that activation of mTORC1 signaling is sufficient to induce chronic hyperglucagonemia as a result of α-cell proliferation, cell size, and mass expansion. Hyperglucagonemia in αTSC2KO was associated with an increase in glucagon content and enhanced glucagon secretion. This model allowed us to identify the effects of chronic hyperglucagonemia on glucose homeostasis by inducing insulin secretion and resistance to glucagon in the liver. Liver glucagon resistance in αTSC2KO mice was characterized by reduced expression of the glucagon receptor (GCGR), PEPCK, and genes involved in amino acid metabolism and urea production. Glucagon resistance in αTSC2KO mice was associated with improved glucose levels in streptozotocin-induced β-cell destruction and high-fat diet-induced glucose intolerance. These studies demonstrate that chronic hyperglucagonemia can improve glucose homeostasis by inducing glucagon resistance in the liver.
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Affiliation(s)
- Nadejda Bozadjieva Kramer
- Department of Medicine, University of Michigan Medical Center, Ann Arbor, MI
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI
- Graduate Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI
| | - Camila Lubaczeuski
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Manuel Blandino-Rosano
- Department of Medicine, University of Michigan Medical Center, Ann Arbor, MI
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Grant Barker
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - George K Gittes
- UPMC Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburg, PA
| | - Alejandro Caicedo
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
- Veterans Affairs Medical Center, Miami, FL
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21
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Cheah PS, Prabhakar S, Yellen D, Beauchamp RL, Zhang X, Kasamatsu S, Bronson RT, Thiele EA, Kwiatkowski DJ, Stemmer-Rachamimov A, György B, Ling KH, Kaneki M, Tannous BA, Ramesh V, Maguire CA, Breakefield XO. Gene therapy for tuberous sclerosis complex type 2 in a mouse model by delivery of AAV9 encoding a condensed form of tuberin. SCIENCE ADVANCES 2021; 7:eabb1703. [PMID: 33523984 PMCID: PMC7793581 DOI: 10.1126/sciadv.abb1703] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 11/18/2020] [Indexed: 05/06/2023]
Abstract
Tuberous sclerosis complex (TSC) results from loss of a tumor suppressor gene - TSC1 or TSC2, encoding hamartin and tuberin, respectively. These proteins formed a complex to inhibit mTORC1-mediated cell growth and proliferation. Loss of either protein leads to overgrowth lesions in many vital organs. Gene therapy was evaluated in a mouse model of TSC2 using an adeno-associated virus (AAV) vector carrying the complementary for a "condensed" form of human tuberin (cTuberin). Functionality of cTuberin was verified in culture. A mouse model of TSC2 was generated by AAV-Cre recombinase disruption of Tsc2-floxed alleles at birth, leading to a shortened lifespan (mean 58 days) and brain pathology consistent with TSC. When these mice were injected intravenously on day 21 with AAV9-cTuberin, the mean survival was extended to 462 days with reduction in brain pathology. This demonstrates the potential of treating life-threatening TSC2 lesions with a single intravenous injection of AAV9-cTuberin.
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Affiliation(s)
- Pike-See Cheah
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital, and Program in Neuroscience, Harvard Medical School, Boston, MA, USA
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Shilpa Prabhakar
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital, and Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - David Yellen
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital, and Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Roberta L Beauchamp
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Xuan Zhang
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital, and Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Shingo Kasamatsu
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- Shriners Hospitals for Children, Boston, MA, USA
| | - Roderick T Bronson
- Rodent Histopathology Core Facility, Harvard Medical School, Boston, MA, USA
| | - Elizabeth A Thiele
- Herscot Center for Tuberous Sclerosis Complex, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- The Pediatric Epilepsy Program, Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
| | | | | | - Bence György
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - King-Hwa Ling
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Masao Kaneki
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- Shriners Hospitals for Children, Boston, MA, USA
| | - Bakhos A Tannous
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital, and Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Vijaya Ramesh
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Casey A Maguire
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital, and Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Xandra O Breakefield
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital, and Program in Neuroscience, Harvard Medical School, Boston, MA, USA.
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22
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Obraztsova K, Basil MC, Rue R, Sivakumar A, Lin SM, Mukhitov AR, Gritsiuta AI, Evans JF, Kopp M, Katzen J, Robichaud A, Atochina-Vasserman EN, Li S, Carl J, Babu A, Morley MP, Cantu E, Beers MF, Frank DB, Morrisey EE, Krymskaya VP. mTORC1 activation in lung mesenchyme drives sex- and age-dependent pulmonary structure and function decline. Nat Commun 2020; 11:5640. [PMID: 33159078 PMCID: PMC7648630 DOI: 10.1038/s41467-020-18979-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 09/23/2020] [Indexed: 12/22/2022] Open
Abstract
Lymphangioleiomyomatosis (LAM) is a rare fatal cystic lung disease due to bi-allelic inactivating mutations in tuberous sclerosis complex (TSC1/TSC2) genes coding for suppressors of the mechanistic target of rapamycin complex 1 (mTORC1). The origin of LAM cells is still unknown. Here, we profile a LAM lung compared to an age- and sex-matched healthy control lung as a hypothesis-generating approach to identify cell subtypes that are specific to LAM. Our single-cell RNA sequencing (scRNA-seq) analysis reveals novel mesenchymal and transitional alveolar epithelial states unique to LAM lung. This analysis identifies a mesenchymal cell hub coordinating the LAM disease phenotype. Mesenchymal-restricted deletion of Tsc2 in the mouse lung produces a mTORC1-driven pulmonary phenotype, with a progressive disruption of alveolar structure, a decline in pulmonary function, increase of rapamycin-sensitive expression of WNT ligands, and profound female-specific changes in mesenchymal and epithelial lung cell gene expression. Genetic inactivation of WNT signaling reverses age-dependent changes of mTORC1-driven lung phenotype, but WNT activation alone in lung mesenchyme is not sufficient for the development of mouse LAM-like phenotype. The alterations in gene expression are driven by distinctive crosstalk between mesenchymal and epithelial subsets of cells observed in mesenchymal Tsc2-deficient lungs. This study identifies sex- and age-specific gene changes in the mTORC1-activated lung mesenchyme and establishes the importance of the WNT signaling pathway in the mTORC1-driven lung phenotype.
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Affiliation(s)
- Kseniya Obraztsova
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Maria C Basil
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Ryan Rue
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Susan M Lin
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alexander R Mukhitov
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Andrei I Gritsiuta
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jilly F Evans
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Meghan Kopp
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jeremy Katzen
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Elena N Atochina-Vasserman
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Shanru Li
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
- Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Justine Carl
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
- Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Apoorva Babu
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
- Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael P Morley
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
- Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Edward Cantu
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael F Beers
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - David B Frank
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
- Children Hospital of Philadelphia, Philadelphia, PA, USA
- Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Edward E Morrisey
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA
- Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Vera P Krymskaya
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Lung Biology Institute, University of Pennsylvania, Philadelphia, PA, USA.
- Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA.
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Hien A, Molinaro G, Liu B, Huber KM, Richter JD. Ribosome profiling in mouse hippocampus: plasticity-induced regulation and bidirectional control by TSC2 and FMRP. Mol Autism 2020; 11:78. [PMID: 33054857 PMCID: PMC7556950 DOI: 10.1186/s13229-020-00384-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 09/23/2020] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Mutations in TSC2 are the most common cause of tuberous sclerosis (TSC), a disorder with a high incidence of autism and intellectual disability. TSC2 regulates mRNA translation required for group 1 metabotropic glutamate receptor-dependent synaptic long-term depression (mGluR-LTD) and behavior, but the identity of mRNAs responsive to mGluR-LTD signaling is largely unknown. METHODS We utilized Tsc2+/- mice as a mouse model of TSC and prepared hippocampal slices from these animals. We induced mGluR-LTD synaptic plasticity in slices and processed the samples for RNA-seq and ribosome profiling to identify differentially expressed genes in Tsc2+/- and following mGluR-LTD synaptic plasticity. RESULTS Ribosome profiling reveals that in Tsc2+/- mouse hippocampal slices, the expression of several mRNAs was dysregulated: terminal oligopyrimidine (TOP)-containing mRNAs decreased, while FMRP-binding targets increased. Remarkably, we observed the opposite changes of FMRP binding targets in Fmr1-/y hippocampi. In wild-type hippocampus, induction of mGluR-LTD caused rapid changes in the steady-state levels of hundreds of mRNAs, many of which are FMRP targets. Moreover, mGluR-LTD failed to promote phosphorylation of eukaryotic elongation factor 2 (eEF2) in TSC mice, and chemically mimicking phospho-eEF2 with low cycloheximide enhances mGluR-LTD in TSC mice. CONCLUSION These results suggest a molecular basis for bidirectional regulation of synaptic plasticity and behavior by TSC2 and FMRP. Our study also suggests that altered mGluR-regulated translation elongation contributes to impaired synaptic plasticity in Tsc2+/- mice.
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Affiliation(s)
- Annie Hien
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
- Medical Scientist Training Program, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| | - Gemma Molinaro
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Botao Liu
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Kimberly M Huber
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Joel D Richter
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA.
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24
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Van Nostrand JL, Hellberg K, Luo EC, Van Nostrand EL, Dayn A, Yu J, Shokhirev MN, Dayn Y, Yeo GW, Shaw RJ. AMPK regulation of Raptor and TSC2 mediate metformin effects on transcriptional control of anabolism and inflammation. Genes Dev 2020; 34:1330-1344. [PMID: 32912901 PMCID: PMC7528705 DOI: 10.1101/gad.339895.120] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 08/12/2020] [Indexed: 12/12/2022]
Abstract
Here, Van Nostrand et al. investigated the mechanisms of action of the biguanide drug metformin by using a new RaptorAA mouse model, in which AMPK phospho-serine sites Ser722 and Ser792 of RAPTOR were mutated to alanine. The hepatic transcriptional response in mice on a high-fat diet treated with metformin was largely ablated by AMPK deficiency under the conditions examined, indicating the essential role of this kinase and its targets in metformin action in vivo. Despite being the frontline therapy for type 2 diabetes, the mechanisms of action of the biguanide drug metformin are still being discovered. In particular, the detailed molecular interplays between the AMPK and the mTORC1 pathway in the hepatic benefits of metformin are still ill defined. Metformin-dependent activation of AMPK classically inhibits mTORC1 via TSC/RHEB, but several lines of evidence suggest additional mechanisms at play in metformin inhibition of mTORC1. Here we investigated the role of direct AMPK-mediated serine phosphorylation of RAPTOR in a new RaptorAA mouse model, in which AMPK phospho-serine sites Ser722 and Ser792 of RAPTOR were mutated to alanine. Metformin treatment of primary hepatocytes and intact murine liver requires AMPK regulation of both RAPTOR and TSC2 to fully inhibit mTORC1, and this regulation is critical for both the translational and transcriptional response to metformin. Transcriptionally, AMPK and mTORC1 were both important for regulation of anabolic metabolism and inflammatory programs triggered by metformin treatment. The hepatic transcriptional response in mice on high-fat diet treated with metformin was largely ablated by AMPK deficiency under the conditions examined, indicating the essential role of this kinase and its targets in metformin action in vivo.
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Affiliation(s)
- Jeanine L Van Nostrand
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Kristina Hellberg
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - En-Ching Luo
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92037, USA
| | - Eric L Van Nostrand
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92037, USA
| | - Alina Dayn
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Jingting Yu
- Razavi Newman Integrative Genomics and Bioinformatics Core, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Maxim N Shokhirev
- Razavi Newman Integrative Genomics and Bioinformatics Core, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Yelena Dayn
- Transgenic Core Facility, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92037, USA
| | - Reuben J Shaw
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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25
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A glycolytic shift in Schwann cells supports injured axons. Nat Neurosci 2020; 23:1215-1228. [PMID: 32807950 DOI: 10.1038/s41593-020-0689-4] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 07/07/2020] [Indexed: 01/09/2023]
Abstract
Axon degeneration is a hallmark of many neurodegenerative disorders. The current assumption is that the decision of injured axons to degenerate is cell-autonomously regulated. Here we show that Schwann cells (SCs), the glia of the peripheral nervous system, protect injured axons by virtue of a dramatic glycolytic upregulation that arises in SCs as an inherent adaptation to axon injury. This glycolytic response, paired with enhanced axon-glia metabolic coupling, supports the survival of axons. The glycolytic shift in SCs is largely driven by the metabolic signaling hub, mammalian target of rapamycin complex 1, and the downstream transcription factors hypoxia-inducible factor 1-alpha and c-Myc, which together promote glycolytic gene expression. The manipulation of glial glycolytic activity through this pathway enabled us to accelerate or delay the degeneration of perturbed axons in acute and subacute rodent axon degeneration models. Thus, we demonstrate a non-cell-autonomous metabolic mechanism that controls the fate of injured axons.
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26
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Feliciano DM. The Neurodevelopmental Pathogenesis of Tuberous Sclerosis Complex (TSC). Front Neuroanat 2020; 14:39. [PMID: 32765227 PMCID: PMC7381175 DOI: 10.3389/fnana.2020.00039] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/10/2020] [Indexed: 12/22/2022] Open
Abstract
Tuberous sclerosis complex (TSC) is a model disorder for understanding brain development because the genes that cause TSC are known, many downstream molecular pathways have been identified, and the resulting perturbations of cellular events are established. TSC, therefore, provides an intellectual framework to understand the molecular and biochemical pathways that orchestrate normal brain development. The TSC1 and TSC2 genes encode Hamartin and Tuberin which form a GTPase activating protein (GAP) complex. Inactivating mutations in TSC genes (TSC1/TSC2) cause sustained Ras homologue enriched in brain (RHEB) activation of the mammalian isoform of the target of rapamycin complex 1 (mTORC1). TOR is a protein kinase that regulates cell size in many organisms throughout nature. mTORC1 inhibits catabolic processes including autophagy and activates anabolic processes including mRNA translation. mTORC1 regulation is achieved through two main upstream mechanisms. The first mechanism is regulation by growth factor signaling. The second mechanism is regulation by amino acids. Gene mutations that cause too much or too little mTORC1 activity lead to a spectrum of neuroanatomical changes ranging from altered brain size (micro and macrocephaly) to cortical malformations to Type I neoplasias. Because somatic mutations often underlie these changes, the timing, and location of mutation results in focal brain malformations. These mutations, therefore, provide gain-of-function and loss-of-function changes that are a powerful tool to assess the events that have gone awry during development and to determine their functional physiological consequences. Knowledge about the TSC-mTORC1 pathway has allowed scientists to predict which upstream and downstream mutations should cause commensurate neuroanatomical changes. Indeed, many of these predictions have now been clinically validated. A description of clinical imaging and histochemical findings is provided in relation to laboratory models of TSC that will allow the reader to appreciate how human pathology can provide an understanding of the fundamental mechanisms of development.
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Affiliation(s)
- David M Feliciano
- Department of Biological Sciences, Clemson University, Clemson, SC, United States
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27
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Carlin D, Halevi AE, Ewan EE, Moore AM, Cavalli V. Nociceptor Deletion of Tsc2 Enhances Axon Regeneration by Inducing a Conditioning Injury Response in Dorsal Root Ganglia. eNeuro 2019; 6:ENEURO.0168-19.2019. [PMID: 31182472 PMCID: PMC6595439 DOI: 10.1523/eneuro.0168-19.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 05/15/2019] [Accepted: 05/18/2019] [Indexed: 12/30/2022] Open
Abstract
Neurons of the PNS are able to regenerate injured axons, a process requiring significant cellular resources to establish and maintain long-distance growth. Genetic activation of mTORC1, a potent regulator of cellular metabolism and protein translation, improves axon regeneration of peripheral neurons by an unresolved mechanism. To gain insight into this process, we activated mTORC1 signaling in mouse nociceptors via genetic deletion of its negative regulator Tsc2. Perinatal deletion of Tsc2 in nociceptors enhanced initial axon growth after sciatic nerve crush, however by 3 d post-injury axon elongation rate became similar to controls. mTORC1 inhibition prior to nerve injury was required to suppress the enhanced axon growth. Gene expression analysis in purified nociceptors revealed that Tsc2-deficient nociceptors had increased activity of regeneration-associated transcription factors (RATFs), including cJun and Atf3, in the absence of injury. Additionally, nociceptor deletion of Tsc2 activated satellite glial cells and macrophages in the dorsal root ganglia (DRG) in a similar manner to nerve injury. Surprisingly, these changes improved axon length but not percentage of initiating axons in dissociated cultures. The pro-regenerative environment in naïve DRG was recapitulated by AAV8-mediated deletion of Tsc2 in adult mice, suggesting that this phenotype does not result from a developmental effect. Consistently, AAV8-mediated Tsc2 deletion did not improve behavioral recovery after a sciatic nerve crush injury despite initially enhanced axon growth. Together, these data show that neuronal mTORC1 activation induces an incomplete pro-regenerative environment in the DRG that improves initial but not later axon growth after nerve injury.
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Affiliation(s)
- Dan Carlin
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110
| | - Alexandra E Halevi
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO 63110
| | - Eric E Ewan
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110
| | - Amy M Moore
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO 63110
| | - Valeria Cavalli
- Department of Neuroscience, Center of Regenerative Medicine, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110
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28
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Blair JD, Bateup HS. New frontiers in modeling tuberous sclerosis with human stem cell-derived neurons and brain organoids. Dev Dyn 2019; 249:46-55. [PMID: 31070828 DOI: 10.1002/dvdy.60] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/01/2019] [Accepted: 05/02/2019] [Indexed: 12/16/2022] Open
Abstract
Recent advances in human stem cell and genome engineering have enabled the generation of genetically defined human cellular models for brain disorders. These models can be established from a patient's own cells and can be genetically engineered to generate isogenic, controlled systems for mechanistic studies. Given the challenges of obtaining and working with primary human brain tissue, these models fill a critical gap in our understanding of normal and abnormal human brain development and provide an important complement to animal models. Recently, there has been major progress in modeling the neuropathophysiology of the canonical "mTORopathy" tuberous sclerosis complex (TSC) with such approaches. Studies using two- and three-dimensional cultures of human neurons and glia have provided new insights into how mutations in the TSC1 and TSC2 genes impact human neural development and function. Here we discuss recent progress in human stem cell-based modeling of TSC and highlight challenges and opportunities for further efforts in this area.
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Affiliation(s)
- John D Blair
- Department of Molecular and Cell Biology, University of California, Berkeley, California
| | - Helen S Bateup
- Department of Molecular and Cell Biology, University of California, Berkeley, California.,Helen Wills Neuroscience Institute, University of California, Berkeley, California.,Chan Zuckerberg Biohub, San Francisco, California
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29
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Du H, Dreier JR, Zarei M, Wu CL, Bronson RW, Kwiatkowski DJ. A novel mouse model of hemangiopericytoma due to loss of Tsc2. Hum Mol Genet 2019; 27:4169-4175. [PMID: 30124871 DOI: 10.1093/hmg/ddy289] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 08/06/2018] [Indexed: 01/01/2023] Open
Abstract
Hemangiopericytoma (HPC) is a rare vascular tumor, which is thought to originate from pericytes. However, no direct evidence for the cell of origin has been found, and the mechanism of HPC tumorigenesis is poorly understood. Here we report that loss of the tumor suppressor gene Tsc2 in pericytes using a FoxD1 promoter driven cre allele (Foxd1tm1(GFP/cre) Amc, FoxD1GC) leads to the formation of HPC in multiple sites. Tsc2ffFoxD1GC mice had stunted growth with seizures and tail and hind limb tremor with a median survival of 110 days. They also showed recombination in brain, spinal cord, tongue, liver, intestine and skeletal muscle. Distinctive perivascular tumors consisting of cells with oval nuclei and scant cytoplasm were identified in multiple sites in all Tsc2ffFoxD1GC mice. Immunohistochemistry staining showed a high expression of phospho-S6-S240/244, a hallmark of activated mTORC1, as well as pericyte markers NG2 and vimentin in these tumors. In summary, we demonstrate that loss of Tsc2 in pericytes generates HPC, the first mouse model of HPC reported.
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Affiliation(s)
- Heng Du
- Division of Pulmonary Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - John R Dreier
- Division of Pulmonary Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Mahsa Zarei
- Division of Pulmonary Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Department of Veterinary Physiology and Pharmacology, Texas A & M University, College Station, TX
| | - Chin-Lee Wu
- Departments of Pathology and Urology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | | | - David J Kwiatkowski
- Division of Pulmonary Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
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30
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Pita-Thomas W, Mahar M, Joshi A, Gan D, Cavalli V. HDAC5 promotes optic nerve regeneration by activating the mTOR pathway. Exp Neurol 2019; 317:271-283. [PMID: 30910408 DOI: 10.1016/j.expneurol.2019.03.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 03/14/2019] [Accepted: 03/21/2019] [Indexed: 11/30/2022]
Abstract
Neurons in the central nervous system (CNS) regenerate poorly compared to their counterparts in the peripheral nervous system. We previously showed that, in peripheral sensory neurons, nuclear HDAC5 inhibits the expression of regenerative associated genes. After nerve injury, HDAC5 is exported to the cytoplasm to promote axon regeneration. Here we investigated the role of HDAC5 in retinal ganglion cells (RGCs), a CNS neuron which fails to survive and regenerate axons after injury. In contrast to PNS neurons, we found that HDAC5 is mostly cytoplasmic in naïve RGCs and its localization is not affected by optic nerve injury, suggesting that HDAC5 does not directly suppress regenerative associated genes in these cells. Manipulation of the PKCμ pathway, the canonical pathway that regulates HDAC5 localization in PNS neurons by phosphorylating serine 259 and 498, and other pathways that regulate nuclear/cytoplasmic transport, did not affect HDAC5 cytoplasmic localization in RGC. Also, an HDAC5 mutant whose serine 259 and 488 were replaced by alanine (HDAC5AA) to prevent phosphorylation and nuclear export showed a predominantly cytoplasmic localization, suggesting that HDAC5 resides mostly in the cytoplasm in RGCs. Interestingly, expression of HDAC5AA, but not HDAC5 wild type, in RGCs in vivo promoted optic nerve regeneration and RGC survival. Mechanistically, we found that HDAC5AA stimulated the survival and regeneration of RGCs by activating the mTOR pathway. Consistently, the combination of HDAC5AA expression and the stimulation of the immune system by zymosan injection had an additive effect in promoting robust axon regeneration. These results reveal the potential of manipulating HDAC5 phosphorylation state to activate the mTOR pathway, offering a new therapeutic target to design drugs that promote axon regeneration in the optic nerve.
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Affiliation(s)
- Wolfgang Pita-Thomas
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, United States of America
| | - Marcus Mahar
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, United States of America
| | - Avni Joshi
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, United States of America
| | - Di Gan
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, United States of America; Department of Neuroscience, Brandeis University, Waltham, MA 02453, United States of America
| | - Valeria Cavalli
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, United States of America; Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO 63110, United States of America; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, United States of America.
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31
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Lam HC, Siroky BJ, Henske EP. Renal disease in tuberous sclerosis complex: pathogenesis and therapy. Nat Rev Nephrol 2018; 14:704-716. [DOI: 10.1038/s41581-018-0059-6] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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32
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Carlin D, Golden JP, Mogha A, Samineni VK, Monk KR, Gereau RW, Cavalli V. Deletion of Tsc2 in Nociceptors Reduces Target Innervation, Ion Channel Expression, and Sensitivity to Heat. eNeuro 2018; 5:ENEURO.0436-17.2018. [PMID: 29766046 PMCID: PMC5952427 DOI: 10.1523/eneuro.0436-17.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 04/13/2018] [Accepted: 04/16/2018] [Indexed: 01/10/2023] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is known to regulate cellular growth pathways, and its genetic activation is sufficient to enhance regenerative axon growth following injury to the central or peripheral nervous systems. However, excess mTORC1 activation may promote innervation defects, and mTORC1 activity mediates injury-induced hypersensitivity, reducing enthusiasm for the pathway as a therapeutic target. While mTORC1 activity is required for full expression of some pain modalities, the effects of pathway activation on nociceptor phenotypes and sensory behaviors are currently unknown. To address this, we genetically activated mTORC1 in mouse peripheral sensory neurons by conditional deletion of its negative regulator Tuberous Sclerosis Complex 2 (Tsc2). Consistent with the well-known role of mTORC1 in regulating cell size, soma size and axon diameter of C-nociceptors were increased in Tsc2-deleted mice. Glabrous skin and spinal cord innervation by C-fiber neurons were also disrupted. Transcriptional profiling of nociceptors enriched by fluorescence-associated cell sorting (FACS) revealed downregulation of multiple classes of ion channels as well as reduced expression of markers for peptidergic nociceptors in Tsc2-deleted mice. In addition to these changes in innervation and gene expression, Tsc2-deleted mice exhibited reduced noxious heat sensitivity and decreased injury-induced cold hypersensitivity, but normal baseline sensitivity to cold and mechanical stimuli. Together, these data show that excess mTORC1 activity in sensory neurons produces changes in gene expression, neuron morphology and sensory behavior.
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Affiliation(s)
- Dan Carlin
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110
| | - Judith P. Golden
- Washington University Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Amit Mogha
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110
| | - Vijay K. Samineni
- Washington University Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Kelly R. Monk
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110
| | - Robert W. Gereau
- Washington University Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Valeria Cavalli
- Department of Neuroscience, Hope Center for Neurological Disorders and Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO 63110
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33
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Wong KM, Beirowski B. Multiple lines of inhibitory feedback on AKT kinase in Schwann cells lacking TSC1/2 hint at distinct functions of mTORC1 and AKT in nerve development. Commun Integr Biol 2018; 11:e1433441. [PMID: 29497474 PMCID: PMC5824964 DOI: 10.1080/19420889.2018.1433441] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 01/02/2018] [Accepted: 01/19/2018] [Indexed: 11/29/2022] Open
Abstract
During nerve development, Schwann cells (SCs) build multilayered myelin sheaths around axons to accelerate nerve conduction. The mechanistic target of rapamycin complex 1 (mTORC1) downstream of PI3K/AKT signaling lately emerged as a central anabolic regulator of myelination. Using mutant mice with sustained mTORC1 hyperactivity in developing SCs we recently uncovered that mTORC1 impedes developmental myelination by promoting proliferation of immature SCs while antagonizing SC differentiation. In contrast, mTORC1 stimulates myelin production, rather than SC proliferation, in already differentiated SCs. Importantly, these diametrical mTORC1 functions were unmasked under settings of greatly suppressed AKT signaling. Here we demonstrate, inter alia, additional mechanisms of feedback inhibition of AKT by mTORC1, such as strikingly elevated PTEN levels in SCs with disruption of the mTORC1 inhibitory complex, TSC1/2. These data lead us to propose a model wherein mTORC1 and AKT have distinct roles in developing SCs that have to be precisely coordinated for normal myelinogenesis.
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Affiliation(s)
- Keit Men Wong
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Bogdan Beirowski
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.,Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
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34
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Klover PJ, Thangapazham RL, Kato J, Wang JA, Anderson SA, Hoffmann V, Steagall WK, Li S, McCart E, Nathan N, Bernstock JD, Wilkerson MD, Dalgard CL, Moss J, Darling TN. Tsc2 disruption in mesenchymal progenitors results in tumors with vascular anomalies overexpressing Lgals3. eLife 2017; 6. [PMID: 28695825 PMCID: PMC5505700 DOI: 10.7554/elife.23202] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 06/01/2017] [Indexed: 12/19/2022] Open
Abstract
Increased mTORC1 signaling from TSC1/TSC2 inactivation is found in cancer and causes tuberous sclerosis complex (TSC). The role of mesenchymal-derived cells in TSC tumorigenesis was investigated through disruption of Tsc2 in craniofacial and limb bud mesenchymal progenitors. Tsc2cKOPrrx1-cre mice had shortened lifespans and extensive hamartomas containing abnormal tortuous, dilated vessels prominent in the forelimbs. Abnormalities were blocked by the mTORC1 inhibitor sirolimus. A Tsc2/mTORC1 expression signature identified in Tsc2-deficient fibroblasts was also increased in bladder cancers with TSC1/TSC2 mutations in the TCGA database. Signature component Lgals3 encoding galectin-3 was increased in Tsc2-deficient cells and serum of Tsc2cKOPrrx1-cre mice. Galectin-3 was increased in TSC-related skin tumors, angiomyolipomas, and lymphangioleiomyomatosis with serum levels in patients with lymphangioleiomyomatosis correlating with impaired lung function and angiomyolipoma presence. Our results demonstrate Tsc2-deficient mesenchymal progenitors cause aberrant morphogenic signals, and identify an expression signature including Lgals3 relevant for human disease of TSC1/TSC2 inactivation and mTORC1 hyperactivity. DOI:http://dx.doi.org/10.7554/eLife.23202.001 Tuberous sclerosis complex is a genetic condition that causes non-cancerous tumours with lots of blood vessels. It is caused by mutations that inactivate either of two genes known as TSC1 and TSC2. A signalling molecule called mTOR also contributes to the disease, and drugs that block its activity provide some relief for patients. However, mTOR regulates a wide variety of molecules and so researchers are looking for which ones are responsible for the formation of the tumours. Mesenchymal cells produce bone, muscle and other structural tissues in the body. They also support the formation of blood vessels. Mice – which are often used as model animals in health research – also have mesenchymal cells and a gene that is very similar to the human TSC2 gene (known as Tsc2). Klover et al. hypothesized that disrupting the Tsc2 gene specifically in the mesenchymal cells of mice may mimic aspects of tuberous sclerosis complex in humans. The experiments show that disrupting Tsc2 in mesenchymal cells does indeed mimic features of the human disease; the mice had shorter lifespans and they developed many tumours with dilated and winding blood vessels. Treating the mice with a drug that inhibits mTOR caused the tumours to shrink. Further experiments show that the loss of Tsc2 alters the production of many proteins involved metabolism, cell growth and sensing the levels of oxygen. For example, mouse cells that lack Tsc2 produce more of a protein called galectin-3, which appears to help blood vessels and tumours to grow in cancers. Klover et al. also studied tumours from patients with tuberous sclerosis complex and a lung disease that is caused by mutations in TSC2 (called lymphangioleiomyomatosis). The experiments found that many tumours produce higher levels of galactin-3 than normal cells. Bladder cancers with mutations in TSC1 or TSC2 also had higher levels of galectin-3, suggesting that other diseases linked with mutations in these genes may also result in increased production of galectin-3. The findings of Klover et al. suggest that galectin-3 may be a useful marker to assess the severity of tuberous sclerosis complex, lymphangioleiomyomatosis and to detect cancers with mutations in TSC1 or TSC2. The next step is to investigate whether galectin-3 alters blood vessels and tumour growth in these conditions. DOI:http://dx.doi.org/10.7554/eLife.23202.002
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Affiliation(s)
- Peter J Klover
- Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, United States
| | - Rajesh L Thangapazham
- Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, United States
| | - Jiro Kato
- Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Ji-An Wang
- Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, United States
| | - Stasia A Anderson
- Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Victoria Hoffmann
- Diagnostic and Research Services Branch, National Institutes of Health, Bethesda, United States
| | - Wendy K Steagall
- Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Shaowei Li
- Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, United States
| | - Elizabeth McCart
- Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, United States
| | - Neera Nathan
- Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, United States.,Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Joshua D Bernstock
- Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, United States
| | - Matthew D Wilkerson
- Department of Anatomy Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, United States.,The American Genome Center, Uniformed Services University of the Health Sciences, Bethesda, United States
| | - Clifton L Dalgard
- Department of Anatomy Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, United States.,The American Genome Center, Uniformed Services University of the Health Sciences, Bethesda, United States
| | - Joel Moss
- Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Thomas N Darling
- Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, United States
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Lee PY, Sykes DB, Ameri S, Kalaitzidis D, Charles JF, Nelson-Maney N, Wei K, Cunin P, Morris A, Cardona AE, Root DE, Scadden DT, Nigrovic PA. The metabolic regulator mTORC1 controls terminal myeloid differentiation. Sci Immunol 2017; 2:2/11/eaam6641. [PMID: 28763796 DOI: 10.1126/sciimmunol.aam6641] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 04/20/2017] [Indexed: 12/11/2022]
Abstract
Monocytes are derived from hematopoietic stem cells through a series of intermediate progenitor stages, but the factors that regulate this process are incompletely defined. Using a Ccr2/Cx3cr1 dual-reporter system to model murine monocyte ontogeny, we conducted a small-molecule screen that identified an essential role of mechanistic target of rapamycin complex 1 (mTORC1) in the development of monocytes and other myeloid cells. Confirmatory studies using mice with inducible deletion of the mTORC1 component Raptor demonstrated absence of mature circulating monocytes, as well as disruption in neutrophil and dendritic cell development, reflecting arrest of terminal differentiation at the granulocyte-monocyte progenitor stage. Conversely, excess activation of mTORC1 through deletion of the mTORC1 inhibitor tuberous sclerosis complex 2 promoted spontaneous myeloid cell development and maturation. Inhibitor studies and stage-specific expression profiling identified failure to down-regulate the transcription factor Myc by the mTORC1 target ribosomal S6 kinase 1 (S6K1) as the mechanistic basis for disrupted myelopoiesis. Together, these findings define the mTORC1-S6K1-Myc pathway as a key checkpoint in terminal myeloid development.
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Affiliation(s)
- Pui Y Lee
- Division of Immunology, Boston Children's Hospital, Boston, MA 02115, USA.,Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - David B Sykes
- Center for Regenerative Medicine, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA
| | - Sarah Ameri
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Demetrios Kalaitzidis
- Center for Regenerative Medicine, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA
| | - Julia F Charles
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Nathan Nelson-Maney
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Kevin Wei
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Pierre Cunin
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Allyn Morris
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Astrid E Cardona
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - David E Root
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA
| | - David T Scadden
- Center for Regenerative Medicine, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA
| | - Peter A Nigrovic
- Division of Immunology, Boston Children's Hospital, Boston, MA 02115, USA. .,Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA
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mTORC1 promotes proliferation of immature Schwann cells and myelin growth of differentiated Schwann cells. Proc Natl Acad Sci U S A 2017; 114:E4261-E4270. [PMID: 28484008 PMCID: PMC5448230 DOI: 10.1073/pnas.1620761114] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The myelination of axons in peripheral nerves requires precisely coordinated proliferation and differentiation of Schwann cells (SCs). We found that the activity of the mechanistic target of rapamycin complex 1 (mTORC1), a key signaling hub for the regulation of cellular growth and proliferation, is progressively extinguished as SCs differentiate during nerve development. To study the effects of different levels of sustained mTORC1 hyperactivity in the SC lineage, we disrupted negative regulators of mTORC1, including TSC2 or TSC1, in developing SCs of mutant mice. Surprisingly, the phenotypes ranged from arrested myelination in nerve development to focal hypermyelination in adulthood, depending on the level and timing of mTORC1 hyperactivity. For example, mice lacking TSC2 in developing SCs displayed hyperproliferation of undifferentiated SCs incompatible with normal myelination. However, these defects and myelination could be rescued by pharmacological mTORC1 inhibition. The subsequent reconstitution of SC mTORC1 hyperactivity in adult animals resulted in focal hypermyelination. Together our data suggest a model in which high mTORC1 activity promotes proliferation of immature SCs and antagonizes SC differentiation during nerve development. Down-regulation of mTORC1 activity is required for terminal SC differentiation and subsequent initiation of myelination. In distinction to this developmental role, excessive SC mTORC1 activity stimulates myelin growth, even overgrowth, in adulthood. Thus, our work delineates two distinct functions of mTORC1 in the SC lineage essential for proper nerve development and myelination. Moreover, our studies show that SCs retain their plasticity to myelinate and remodel myelin via mTORC1 throughout life.
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Jacobs BL, McNally RM, Kim KJ, Blanco R, Privett RE, You JS, Hornberger TA. Identification of mechanically regulated phosphorylation sites on tuberin (TSC2) that control mechanistic target of rapamycin (mTOR) signaling. J Biol Chem 2017; 292:6987-6997. [PMID: 28289099 PMCID: PMC5409467 DOI: 10.1074/jbc.m117.777805] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 03/08/2017] [Indexed: 12/31/2022] Open
Abstract
Mechanistic target of rapamycin (mTOR) signaling is necessary to generate a mechanically induced increase in skeletal muscle mass, but the mechanism(s) through which mechanical stimuli regulate mTOR signaling remain poorly defined. Recent studies have suggested that Ras homologue enriched in brain (Rheb), a direct activator of mTOR, and its inhibitor, the GTPase-activating protein tuberin (TSC2), may play a role in this pathway. To address this possibility, we generated inducible and skeletal muscle-specific knock-out mice for Rheb (iRhebKO) and TSC2 (iTSC2KO) and mechanically stimulated muscles from these mice with eccentric contractions (EC). As expected, the knock-out of TSC2 led to an elevation in the basal level of mTOR signaling. Moreover, we found that the magnitude of the EC-induced activation of mTOR signaling was significantly blunted in muscles from both inducible and skeletal muscle-specific knock-out mice for Rheb and iTSC2KO mice. Using mass spectrometry, we identified six sites on TSC2 whose phosphorylation was significantly altered by the EC treatment. Employing a transient transfection-based approach to rescue TSC2 function in muscles of the iTSC2KO mice, we demonstrated that these phosphorylation sites are required for the role that TSC2 plays in the EC-induced activation of mTOR signaling. Importantly, however, these phosphorylation sites were not required for an insulin-induced activation of mTOR signaling. As such, our results not only establish a critical role for Rheb and TSC2 in the mechanical activation of mTOR signaling, but they also expose the existence of a previously unknown branch of signaling events that can regulate the TSC2/mTOR pathway.
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Affiliation(s)
- Brittany L Jacobs
- From the Department of Comparative Biosciences and.,the School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706
| | - Rachel M McNally
- From the Department of Comparative Biosciences and.,the School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706
| | - Kook-Joo Kim
- From the Department of Comparative Biosciences and.,the School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706
| | - Rocky Blanco
- From the Department of Comparative Biosciences and.,the School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706
| | - Rachel E Privett
- From the Department of Comparative Biosciences and.,the School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706
| | - Jae-Sung You
- From the Department of Comparative Biosciences and.,the School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706
| | - Troy A Hornberger
- From the Department of Comparative Biosciences and .,the School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706
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Chronic signaling via the metabolic checkpoint kinase mTORC1 induces macrophage granuloma formation and marks sarcoidosis progression. Nat Immunol 2017; 18:293-302. [PMID: 28092373 PMCID: PMC5321578 DOI: 10.1038/ni.3655] [Citation(s) in RCA: 160] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 12/02/2016] [Indexed: 12/14/2022]
Abstract
Aggregation of hypertrophic macrophages constitutes the basis of all granulomatous diseases such as tuberculosis or sarcoidosis and is decisive for disease pathogenesis. However, macrophage-intrinsic pathways driving granuloma initiation and maintenance remain elusive. Here we show that activation of the metabolic checkpoint kinase mTORC1 in macrophages by deletion of Tsc2 was sufficient to induce hypertrophy and proliferation resulting in excessive granuloma formation in vivo. TSC2-deficient macrophages formed mTORC1-dependent granulomatous structures in vitro and showed constitutive proliferation mediated by the neo-expression of cyclin-dependent kinase 4 (CDK4). Moreover, mTORC1 promoted metabolic reprogramming via CDK4 towards increased glycolysis, while simultaneously inhibiting NF-κB signaling and apoptosis. Inhibition of mTORC1 induced apoptosis and completely resolved granulomas in myeloid TSC2-deficient mice. In human sarcoidosis patients mTORC1 activation, macrophage proliferation, and glycolysis were identified as hallmarks that correlated with clinical disease progression. Collectively, TSC2 maintains macrophage quiescence and prevents mTORC1-dependent granulomatous disease with clinical implications for sarcoidosis.
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Ren S, Luo Y, Chen H, Warburton D, Lam HC, Wang LL, Chen P, Henske EP, Shi W. Inactivation of Tsc2 in Mesoderm-Derived Cells Causes Polycystic Kidney Lesions and Impairs Lung Alveolarization. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:3261-3272. [PMID: 27768862 DOI: 10.1016/j.ajpath.2016.08.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 08/09/2016] [Accepted: 08/29/2016] [Indexed: 01/15/2023]
Abstract
The tuberous sclerosis complex (TSC) proteins are critical negative regulators of the mammalian/mechanistic target of rapamycin complex 1 pathway. Germline mutations of TSC1 or TSC2 cause TSC, affecting multiple organs, including the kidney and lung, and causing substantial morbidity and mortality. The mechanisms of organ-specific disease in TSC remain incompletely understood, and the impact of TSC inactivation on mesenchymal lineage cells has not been specifically studied. We deleted Tsc2 specifically in mesoderm-derived mesenchymal cells of multiple organs in mice using the Dermo1-Cre driver. The Dermo1-Cre-driven Tsc2 conditional knockout mice had body growth retardation and died approximately 3 weeks after birth. Significant phenotypes were observed in the postnatal kidney and lung. Inactivation of Tsc2 in kidney mesenchyme caused polycystic lesions starting from the second week of age, with increased cell proliferation, tubular epithelial hyperplasia, and epithelial-mesenchymal transition. In contrast, Tsc2 deletion in lung mesenchyme led to decreased cell proliferation, reduced postnatal alveolarization, and decreased differentiation with reduced numbers of alveolar myofibroblast and type II alveolar epithelial cells. Two major findings thus result from this model: inactivation of Tsc2 in mesoderm-derived cells causes increased cell proliferation in the kidneys but reduced proliferation in the lungs, and inactivation of Tsc2 in mesoderm-derived cells causes epithelial-lined renal cysts. Therefore, Tsc2-mTOR signaling in mesenchyme is essential for the maintenance of renal structure and for lung alveolarization.
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Affiliation(s)
- Siying Ren
- Department of Respiratory Medicine, The Second Xiangya Hospital, Central-South University, Changsha, People's Republic of China; Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Yongfeng Luo
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Hui Chen
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - David Warburton
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California; Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Hilaire C Lam
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Larry L Wang
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Ping Chen
- Department of Respiratory Medicine, The Second Xiangya Hospital, Central-South University, Changsha, People's Republic of China
| | - Elizabeth P Henske
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.
| | - Wei Shi
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California; Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California.
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Taneike M, Nishida K, Omiya S, Zarrinpashneh E, Misaka T, Kitazume-Taneike R, Austin R, Takaoka M, Yamaguchi O, Gambello MJ, Shah AM, Otsu K. mTOR Hyperactivation by Ablation of Tuberous Sclerosis Complex 2 in the Mouse Heart Induces Cardiac Dysfunction with the Increased Number of Small Mitochondria Mediated through the Down-Regulation of Autophagy. PLoS One 2016; 11:e0152628. [PMID: 27023784 PMCID: PMC4811538 DOI: 10.1371/journal.pone.0152628] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 03/10/2016] [Indexed: 11/19/2022] Open
Abstract
Mammalian target of rapamycin complex 1 (mTORC1) is a key regulator of cell growth, proliferation and metabolism. mTORC1 regulates protein synthesis positively and autophagy negatively. Autophagy is a major system to manage bulk degradation and recycling of cytoplasmic components and organelles. Tuberous sclerosis complex (TSC) 1 and 2 form a heterodimeric complex and inactivate Ras homolog enriched in brain, resulting in inhibition of mTORC1. Here, we investigated the effects of hyperactivation of mTORC1 on cardiac function and structure using cardiac-specific TSC2-deficient (TSC2-/-) mice. TSC2-/- mice were born normally at the expected Mendelian ratio. However, the median life span of TSC2-/- mice was approximately 10 months and significantly shorter than that of control mice. TSC2-/- mice showed cardiac dysfunction and cardiomyocyte hypertrophy without considerable fibrosis, cell infiltration or apoptotic cardiomyocyte death. Ultrastructural analysis of TSC2-/- hearts revealed misalignment, aggregation and a decrease in the size and an increase in the number of mitochondria, but the mitochondrial function was maintained. Autophagic flux was inhibited, while the phosphorylation level of S6 or eukaryotic initiation factor 4E -binding protein 1, downstream of mTORC1, was increased. The upregulation of autophagic flux by trehalose treatment attenuated the cardiac phenotypes such as cardiac dysfunction and structural abnormalities of mitochondria in TSC2-/- hearts. The results suggest that autophagy via the TSC2-mTORC1 signaling pathway plays an important role in maintenance of cardiac function and mitochondrial quantity and size in the heart and could be a therapeutic target to maintain mitochondrial homeostasis in failing hearts.
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Affiliation(s)
- Manabu Taneike
- Cardiovascular Division, King’s College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | - Kazuhiko Nishida
- Cardiovascular Division, King’s College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | - Shigemiki Omiya
- Cardiovascular Division, King’s College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | - Elham Zarrinpashneh
- Cardiovascular Division, King’s College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | - Tomofumi Misaka
- Cardiovascular Division, King’s College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | - Rika Kitazume-Taneike
- Cardiovascular Division, King’s College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | - Ruth Austin
- Cardiovascular Division, King’s College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | - Minoru Takaoka
- Cardiovascular Division, King’s College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | - Osamu Yamaguchi
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Michael J. Gambello
- Division of Medical Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Ajay M. Shah
- Cardiovascular Division, King’s College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | - Kinya Otsu
- Cardiovascular Division, King’s College London British Heart Foundation Centre of Excellence, London, United Kingdom
- * E-mail:
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Complex Neurological Phenotype in Mutant Mice Lacking Tsc2 in Excitatory Neurons of the Developing Forebrain(123). eNeuro 2015; 2:eN-NWR-0046-15. [PMID: 26693177 PMCID: PMC4676199 DOI: 10.1523/eneuro.0046-15.2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 09/09/2015] [Accepted: 09/14/2015] [Indexed: 11/25/2022] Open
Abstract
Mutations in the TSC1 and TSC2 genes cause tuberous sclerosis complex (TSC), a genetic disease often associated with epilepsy, intellectual disability, and autism, and characterized by the presence of anatomical malformations in the brain as well as tumors in other organs. The TSC1 and TSC2 proteins form a complex that inhibits mammalian target of rapamycin complex 1 (mTORC1) signaling. Previous animal studies demonstrated that Tsc1 or Tsc2 loss of function in the developing brain affects the intrinsic development of neural progenitor cells, neurons, or glia. However, the interplay between different cellular elements during brain development was not previously investigated. In this study, we generated a novel mutant mouse line (NEX-Tsc2) in which the Tsc2 gene is deleted specifically in postmitotic excitatory neurons of the developing forebrain. Homozygous mutant mice failed to thrive and died prematurely, whereas heterozygous mice appeared normal. Mutant mice exhibited distinct neuroanatomical abnormalities, including malpositioning of selected neuronal populations, neuronal hypertrophy, and cortical astrogliosis. Intrinsic neuronal defects correlated with increased mTORC1 signaling, whereas astrogliosis did not result from altered intrinsic signaling, since these cells were not directly affected by the gene knockout strategy. All neuronal and non-neuronal abnormalities were suppressed by continuous postnatal treatment with the mTORC1 inhibitor RAD001. The data suggest that the loss of Tsc2 and mTORC1 signaling activation in excitatory neurons not only disrupts their intrinsic development, but also disrupts the development of cortical astrocytes, likely through the mTORC1-dependent expression of abnormal signaling proteins. This work thus provides new insights into cell-autonomous and non-cell-autonomous functions of Tsc2 in brain development.
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42
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Moon UY, Park JY, Park R, Cho JY, Hughes LJ, McKenna J, Goetzl L, Cho SH, Crino PB, Gambello MJ, Kim S. Impaired Reelin-Dab1 Signaling Contributes to Neuronal Migration Deficits of Tuberous Sclerosis Complex. Cell Rep 2015; 12:965-78. [PMID: 26235615 PMCID: PMC4536164 DOI: 10.1016/j.celrep.2015.07.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 06/01/2015] [Accepted: 07/07/2015] [Indexed: 01/06/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is associated with neurodevelopmental abnormalities, including defects in neuronal migration. However, the alterations in cell signaling mechanisms critical for migration and final positioning of neurons in TSC remain unclear. Our detailed cellular analyses reveal that reduced Tsc2 in newborn neurons causes abnormalities in leading processes of migrating neurons, accompanied by significantly delayed migration. Importantly, we demonstrate that Reelin-Dab1 signaling is aberrantly regulated in TSC mouse models and in cortical tubers from TSC patients owing to enhanced expression of the E3 ubiquitin ligase Cul5, a known mediator of pDab1 ubiquitination. Likewise, mTORC1 activation by Rheb overexpression generates similar neuronal and Reelin-Dab1 signaling defects, and directly upregulates Cul5 expression. Inhibition of mTORC1 by rapamycin treatment or by reducing Cul5 largely restores normal leading processes and positioning of migrating neurons. Thus, disrupted Reelin-Dab1 signaling is critically involved in the neuronal migration defects of TSC.
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Affiliation(s)
- Uk Yeol Moon
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Jun Young Park
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Raehee Park
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Jennifer Y Cho
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Lucinda J Hughes
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Graduate Program of Biomedical Sciences, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - James McKenna
- Department of Human Genetics, Emory University, School of Medicine, Atlanta, GA 30322, USA
| | - Laura Goetzl
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Obstetrics Gynecology and Reproductive Sciences, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Seo-Hee Cho
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Peter B Crino
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Neurology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Michael J Gambello
- Department of Human Genetics, Emory University, School of Medicine, Atlanta, GA 30322, USA
| | - Seonhee Kim
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
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Commandeur AE, Styer AK, Teixeira JM. Epidemiological and genetic clues for molecular mechanisms involved in uterine leiomyoma development and growth. Hum Reprod Update 2015; 21:593-615. [PMID: 26141720 DOI: 10.1093/humupd/dmv030] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 06/09/2015] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Uterine leiomyomas (fibroids) are highly prevalent benign smooth muscle tumors of the uterus. In the USA, the lifetime risk for women developing uterine leiomyomas is estimated as up to 75%. Except for hysterectomy, most therapies or treatments often provide only partial or temporary relief and are not successful in every patient. There is a clear racial disparity in the disease; African-American women are estimated to be three times more likely to develop uterine leiomyomas and generally develop more severe symptoms. There is also familial clustering between first-degree relatives and twins, and multiple inherited syndromes in which fibroid development occurs. Leiomyomas have been described as clonal and hormonally regulated, but despite the healthcare burden imposed by the disease, the etiology of uterine leiomyomas remains largely unknown. The mechanisms involved in their growth are also essentially unknown, which has contributed to the slow progress in development of effective treatment options. METHODS A comprehensive PubMed search for and critical assessment of articles related to the epidemiological, biological and genetic clues for uterine leiomyoma development was performed. The individual functions of some of the best candidate genes are explained to provide more insight into their biological function and to interconnect and organize genes and pathways in one overarching figure that represents the current state of knowledge about uterine leiomyoma development and growth. RESULTS In this review, the widely recognized roles of estrogen and progesterone in uterine leiomyoma pathobiology on the basis of clinical and experimental data are presented. This is followed by fundamental aspects and concepts including the possible cellular origin of uterine fibroids. The central themes in the subsequent parts are cytogenetic aberrations in leiomyomas and the racial/ethnic disparities in uterine fibroid biology. Then, the attributes of various in vitro and in vivo, human syndrome, rodent xenograft, naturally mutant, and genetically modified models used to study possible molecular mechanisms of leiomyoma development and growth are described. Particular emphasis is placed on known links to fibrosis, hypertrophy, and hyperplasia and genes that are potentially important in these processes. CONCLUSIONS Menstrual cycle-related injury and repair and coinciding hormonal cycling appears to affect myometrial stem cells that, at a certain stage of fibroid development, often obtain cytogenetic aberrations and mutations of Mediator complex subunit 12 (MED12). Mammalian target of rapamycin (mTOR), a master regulator of proliferation, is activated in many of these tumors, possibly by mechanisms that are similar to some human fibrosis syndromes and/or by mutation of upstream tumor suppressor genes. Animal models of the disease support some of these dysregulated pathways in fibroid etiology or pathogenesis, but none are definitive. All of this suggests that there are likely several key mechanisms involved in the disease that, in addition to increasing the complexity of uterine fibroid pathobiology, offer possible approaches for patient-specific therapies. A final model that incorporates many of these reported mechanisms is presented with a discussion of their implications for leiomyoma clinical practice.
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Affiliation(s)
- Arno E Commandeur
- Center for Reproductive Medicine, Women's and Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Aaron K Styer
- Vincent Center for Reproductive Biology, Department of Obstetrics, Gynecology, and Reproductive Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jose M Teixeira
- Department of Obstetrics, Gynecology and Reproductive Biology, College of Human Medicine, Michigan State University, 333 Bostwick Ave NE, 4018A, Grand Rapids, MI, USA Department of Women's Health, Spectrum Health Systems, Grand Rapids, MI, USA
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44
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Kirschstein T, Köhling R. Animal models of tumour-associated epilepsy. J Neurosci Methods 2015; 260:109-17. [PMID: 26092434 DOI: 10.1016/j.jneumeth.2015.06.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 06/05/2015] [Accepted: 06/08/2015] [Indexed: 01/26/2023]
Abstract
Brain tumours cause a sizeable proportion of epilepsies in adulthood, and actually can be etiologically responsible also for childhood epilepsies. Conversely, seizures are often first clinical signs of a brain tumour. Nevertheless, several issues of brain-tumour associated seizures and epilepsies are far from understood, or clarified regarding clinical consensus. These include both the specific mechanisms of epileptogenesis related to different tumour types, the possible relationship between malignancy and seizure emergence, the interaction between tumour mass and surrounding neuronal networks, and - not least - the best treatment options depending on different tumour types. To investigate these issues, experimental models of tumour-induced epilepsies are necessary. This review concentrates on the description of currently used models, focusing on methodological aspects. It highlights advantages and shortcomings of these models, and identifies future experimental challenges.
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Affiliation(s)
- Timo Kirschstein
- Oscar-Langendorff-Institute of Physiology, Rostock University Medical Center, Gertrudenstrasse 9, 18057 Rostock, Germany
| | - Rüdiger Köhling
- Oscar-Langendorff-Institute of Physiology, Rostock University Medical Center, Gertrudenstrasse 9, 18057 Rostock, Germany.
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Pollizzi KN, Patel CH, Sun IH, Oh MH, Waickman AT, Wen J, Delgoffe GM, Powell JD. mTORC1 and mTORC2 selectively regulate CD8⁺ T cell differentiation. J Clin Invest 2015; 125:2090-108. [PMID: 25893604 DOI: 10.1172/jci77746] [Citation(s) in RCA: 291] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 03/12/2015] [Indexed: 12/16/2022] Open
Abstract
Activation of mTOR-dependent pathways regulates the specification and differentiation of CD4+ T effector cell subsets. Herein, we show that mTOR complex 1 (mTORC1) and mTORC2 have distinct roles in the generation of CD8+ T cell effector and memory populations. Evaluation of mice with a T cell-specific deletion of the gene encoding the negative regulator of mTORC1, tuberous sclerosis complex 2 (TSC2), resulted in the generation of highly glycolytic and potent effector CD8+ T cells; however, due to constitutive mTORC1 activation, these cells retained a terminally differentiated effector phenotype and were incapable of transitioning into a memory state. In contrast, CD8+ T cells deficient in mTORC1 activity due to loss of RAS homolog enriched in brain (RHEB) failed to differentiate into effector cells but retained memory characteristics, such as surface marker expression, a lower metabolic rate, and increased longevity. However, these RHEB-deficient memory-like T cells failed to generate recall responses as the result of metabolic defects. While mTORC1 influenced CD8+ T cell effector responses, mTORC2 activity regulated CD8+ T cell memory. mTORC2 inhibition resulted in metabolic reprogramming, which enhanced the generation of CD8+ memory cells. Overall, these results define specific roles for mTORC1 and mTORC2 that link metabolism and CD8+ T cell effector and memory generation and suggest that these functions have the potential to be targeted for enhancing vaccine efficacy and antitumor immunity.
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Pollizzi KN, Waickman AT, Patel CH, Sun IH, Powell JD. Cellular size as a means of tracking mTOR activity and cell fate of CD4+ T cells upon antigen recognition. PLoS One 2015; 10:e0121710. [PMID: 25849206 PMCID: PMC4388710 DOI: 10.1371/journal.pone.0121710] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 02/17/2015] [Indexed: 11/18/2022] Open
Abstract
mTOR is a central integrator of metabolic and immunological stimuli, dictating immune cell activation, proliferation and differentiation. In this study, we demonstrate that within a clonal population of activated T cells, there exist both mTORhi and mTORlo cells exhibiting highly divergent metabolic and immunologic functions. By taking advantage of the role of mTOR activation in controlling cellular size, we demonstrate that upon antigen recognition, mTORhi CD4+ T cells are destined to become highly glycolytic effector cells. Conversely, mTORlo T cells preferentially develop into long-lived cells that express high levels of Bcl-2, CD25, and CD62L. Furthermore, mTORlo T cells have a greater propensity to differentiate into suppressive Foxp3+ T regulatory cells, and this paradigm was also observed in human CD4+ T cells. Overall, these studies provide the opportunity to track the development of effector and memory T cells from naïve precursors, as well as facilitate the interrogation of immunologic and metabolic programs that inform these fates.
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Affiliation(s)
- Kristen N. Pollizzi
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Adam T. Waickman
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Chirag H. Patel
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Im Hong Sun
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Jonathan D. Powell
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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Rozas NS, Redell JB, McKenna J, Moore AN, Gambello MJ, Dash PK. Prolonging the survival of Tsc2 conditional knockout mice by glutamine supplementation. Biochem Biophys Res Commun 2015; 457:635-9. [PMID: 25613864 PMCID: PMC4386275 DOI: 10.1016/j.bbrc.2015.01.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 01/10/2015] [Indexed: 10/24/2022]
Abstract
The genetic disease tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by loss of function mutations in either TSC1 (hamartin) or TSC2 (tuberin), which serve as negative regulators of mechanistic target of rapamycin complex 1 (mTORC1) activity. TSC patients exhibit developmental brain abnormalities and tuber formations that are associated with neuropsychological and neurocognitive impairments, seizures and premature death. Mechanistically, TSC1 and TSC2 loss of function mutations result in abnormally high mTORC1 activity. Thus, the development of a strategy to inhibit abnormally high mTORC1 activity may have therapeutic value in the treatment of TSC. mTORC1 is a master regulator of growth processes, and its activity can be reduced by withdrawal of growth factors, decreased energy availability, and by the immunosuppressant rapamycin. Recently, glutamine has been shown to alter mTORC1 activity in a TSC1-TSC2 independent manner in cells cultured under amino acid- and serum-deprived conditions. Since starvation culture conditions are not physiologically relevant, we examined if glutamine can regulate mTORC1 in non-deprived cells and in a murine model of TSC. Our results show that glutamine can reduce phosphorylation of S6 and S6 kinase, surrogate indicators of mTORC1 activity, in both deprived and non-deprived cells, although higher concentrations were required for non-deprived cultures. When administered orally to TSC2 knockout mice, glutamine reduced S6 phosphorylation in the brain and significantly prolonged their lifespan. Taken together, these results suggest that glutamine supplementation can be used as a potential treatment for TSC.
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Affiliation(s)
- Natalia S Rozas
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, TX 77225, USA
| | - John B Redell
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, TX 77225, USA
| | - James McKenna
- Department of Human Genetics, Emory University, Atlanta, GA 30322, USA
| | - Anthony N Moore
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, TX 77225, USA
| | | | - Pramod K Dash
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, TX 77225, USA.
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Rozas NS, Redell JB, Hill JL, McKenna J, Moore AN, Gambello MJ, Dash PK. Genetic activation of mTORC1 signaling worsens neurocognitive outcome after traumatic brain injury. J Neurotrauma 2014; 32:149-58. [PMID: 25025304 DOI: 10.1089/neu.2014.3469] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Although the mechanisms that contribute to the development of traumatic brain injury (TBI)-related deficits are not fully understood, it has been proposed that altered energy utilization may be a contributing factor. The tuberous sclerosis complex, a heterodimer composed of hamartin/Tsc-1 and tuberin/Tsc-2, is a critical regulatory node that integrates nutritional and growth signals to govern energy using processes by regulating the activity of mechanistic Target of Rapamycin complex 1 (mTORC1). mTORC1 activation results in enhanced protein synthesis, an energy consuming process. We show that mice that have a heterozygous deletion of Tsc2 exhibit elevated basal mTORC1 activity in the cortex and the hippocampus while still exhibiting normal motor and neurocognitive functions. In addition, a mild closed head injury (mCHI) that did not activate mTORC1 in wild-type mice resulted in a further increase in mTORC1 activity in Tsc2(+/KO) mice above the level of activity observed in uninjured Tsc2(+/KO) mice. This enhanced level of increased mTORC1 activity was associated with worsened cognitive function as assessed using the Morris water maze and context discrimination tasks. These results suggest that there is a threshold of increased mTORC1 activity after a TBI that is detrimental to neurobehavioral performance, and interventions to inhibit excessive mTORC1 activation may be beneficial to neurocognitive outcome.
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Affiliation(s)
- Natalia S Rozas
- 1 Department of Neurobiology and Anatomy, the University of Texas Medical School , Houston, Texas
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Kaneko-Tarui T, Commandeur AE, Patterson AL, DeKuiper JL, Petillo D, Styer AK, Teixeira JM. Hyperplasia and fibrosis in mice with conditional loss of the TSC2 tumor suppressor in Müllerian duct mesenchyme-derived myometria. Mol Hum Reprod 2014; 20:1126-34. [PMID: 25189766 DOI: 10.1093/molehr/gau077] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Uterine leiomyomata are the most common tumors found in the female reproductive tract. Despite the high prevalence and associated morbidities of these benign tumors, little is known about the molecular basis of uterine leiomyoma development and progression. Loss of the Tuberous Sclerosis 2 (TSC2) tumor suppressor has been proposed as a mechanism important for the etiology of uterine leiomyomata based on the Eker rat model. However, conflicting evidence showing increased TSC2 expression has been reported in human uterine leiomyomata, suggesting that TSC2 might not be involved in the pathogenesis of this disorder. We have produced mice with conditional deletion of the Tsc2 gene in the myometria to determine whether loss of TSC2 leads to leiomyoma development in murine uteri. Myometrial hyperplasia and increased collagen deposition was observed in Tsc2(cKO) mice compared with control mice, but no leiomyomata were detected by post-natal week 24. Increased signaling activity of mammalian target of rapamycin complex 1, which is normally repressed by TSC2, was also detected in the myometria of Tsc2(cKO) mice. Treatment of the mutant mice with rapamycin significantly inhibited myometrial expansion, but treatment with the progesterone receptor modulator, mifepristone, did not. The ovaries of the Tsc2(cKO) mice appeared normal, but half the mice were infertile and most of the other half became infertile after a single litter, which was likely due to oviductal blockage. Our study shows that although TSC2 loss alone does not lead to leiomyoma development, it does lead to myometrial hyperplasia and fibrosis.
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Affiliation(s)
- Tomoko Kaneko-Tarui
- Vincent Center for Reproductive Biology, Department of Obstetrics, Gynecology, and Reproductive Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Arno E Commandeur
- Vincent Center for Reproductive Biology, Department of Obstetrics, Gynecology, and Reproductive Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Amanda L Patterson
- Department of Obstetrics, Gynecology and Reproductive Biology, College of Human Medicine, Michigan State University, Grand Rapids, MI, USA
| | - Justin L DeKuiper
- Department of Obstetrics, Gynecology and Reproductive Biology, College of Human Medicine, Michigan State University, Grand Rapids, MI, USA
| | - David Petillo
- Department of Obstetrics, Gynecology and Reproductive Biology, College of Human Medicine, Michigan State University, Grand Rapids, MI, USA
| | - Aaron K Styer
- Vincent Center for Reproductive Biology, Department of Obstetrics, Gynecology, and Reproductive Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jose M Teixeira
- Department of Obstetrics, Gynecology and Reproductive Biology, College of Human Medicine, Michigan State University, Grand Rapids, MI, USA
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Tsc2 is a molecular checkpoint controlling osteoblast development and glucose homeostasis. Mol Cell Biol 2014; 34:1850-62. [PMID: 24591652 DOI: 10.1128/mcb.00075-14] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Insulin signaling in osteoblasts regulates global energy balance by stimulating the production of osteocalcin, a bone-derived protein that promotes insulin production and action. To identify the signaling pathways in osteoblasts that mediate insulin's effects on bone and energy metabolism, we examined the function of the tuberous sclerosis 2 (Tsc2) protein, a key target important in coordinating nutrient signaling. Here, we show that loss of Tsc2 in osteoblasts constitutively activates mTOR and destabilizes Irs1, causing osteoblasts to differentiate poorly and become resistant to insulin. Young Tsc2 mutant mice demonstrate hypoglycemia with increased levels of insulin and undercarboxylated osteocalcin. However, with age, Tsc2 mutants develop metabolic features similar to mice lacking the insulin receptor in the osteoblast, including peripheral adiposity, hyperglycemia, and decreased pancreatic β cell mass. These metabolic abnormalities appear to result from chronic elevations in undercarboxylated osteocalcin that lead to downregulation of the osteocalcin receptor and desensitization of the β cell to this hormone. Removal of a single mTOR allele from the Tsc2 mutant mice largely normalizes the bone and metabolic abnormalities. Together, these findings suggest that Tsc2 serves as a key checkpoint in the osteoblast that is required for proper insulin signaling and acts to ensure normal bone acquisition and energy homeostasis.
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