1
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Lv K, Tong W. Hidden conformational codes. Blood 2023; 142:1766-1768. [PMID: 37995103 DOI: 10.1182/blood.2023022061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2023] Open
Affiliation(s)
- Kaosheng Lv
- Southern University of Science and Technology
| | - Wei Tong
- Children's Hospital of Philadelphia
- Perelman School of Medicine at the University of Pennsylvania
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2
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Papadopoulos N, Pristavec A, Nédélec A, Levy G, Staerk J, Constantinescu SN. Modulation of human thrombopoietin receptor conformations uncouples JAK2 V617F-driven activation from cytokine-induced stimulation. Blood 2023; 142:1818-1830. [PMID: 37616564 DOI: 10.1182/blood.2022019580] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 07/25/2023] [Accepted: 07/27/2023] [Indexed: 08/26/2023] Open
Abstract
The thrombopoietin receptor (TpoR) plays a central role in myeloproliferative neoplasms (MPNs). Mutations in JAK2, calreticulin, or TpoR itself drive the constitutive activation of TpoR and uncontrolled proliferation and differentiation of hematopoietic stem cells and progenitors. The JAK2 V617F mutation is responsible for most MPNs, and all driver mutants induce pathologic TpoR activation. Existing therapeutic strategies have focused on JAK2 kinase inhibitors that are unable to differentiate between the mutated MPN clone and healthy cells. Surprisingly, the targeting of TpoR itself has remained poorly explored despite its central role in pathology. Here, we performed a comprehensive characterization of human TpoR activation under physiological and pathological conditions, focusing on the JAK2 V617F mutant. Using a system of controlled dimerization of the transmembrane and cytosolic domains of TpoR, we discovered that human TpoR (hTpoR) adopts different dimeric conformations upon Tpo-induced vs JAK2 V617F-mediated activation. We identified the amino acids and specific dimeric conformation of hTpoR responsible for activation in complex with JAK2 V617F and confirmed our findings in the full-length receptor context in hematopoietic cell lines and primary bone marrow cells. Remarkably, we found that the modulation of hTpoR conformations by point mutations allowed for specific inhibition of JAK2 V617F-driven activation without affecting Tpo-induced signaling. Our results demonstrate that modulation of the hTpoR conformation is a viable therapeutic strategy for JAK2 V617F-positive MPNs and set the path for novel drug development by identifying precise residues of hTpoR involved in JAK2 V617F-specific activation.
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Affiliation(s)
- Nicolas Papadopoulos
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, Brussels, Belgium
- Walloon Excellence in Life Sciences and Biotechnology Department, Walloon Excellence Research Institute, Wavre, Belgium
| | - Ajda Pristavec
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Audrey Nédélec
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, Brussels, Belgium
- Walloon Excellence in Life Sciences and Biotechnology Department, Walloon Excellence Research Institute, Wavre, Belgium
| | - Gabriel Levy
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, Brussels, Belgium
- Walloon Excellence in Life Sciences and Biotechnology Department, Walloon Excellence Research Institute, Wavre, Belgium
| | - Judith Staerk
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, Brussels, Belgium
- Centre for Molecular Medicine Norway, Nordic European Molecular Biology Laboratory Partnership, University of Oslo, Oslo, Norway
| | - Stefan N Constantinescu
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- Ludwig Institute for Cancer Research, Brussels, Belgium
- Walloon Excellence in Life Sciences and Biotechnology Department, Walloon Excellence Research Institute, Wavre, Belgium
- Nuffield Department of Medicine, Ludwig Institute for Cancer Research, Oxford University, Oxford, United Kingdom
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3
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Pogozheva ID, Cherepanov S, Park SJ, Raghavan M, Im W, Lomize AL. Structural Modeling of Cytokine-Receptor-JAK2 Signaling Complexes Using AlphaFold Multimer. J Chem Inf Model 2023; 63:5874-5895. [PMID: 37694948 DOI: 10.1021/acs.jcim.3c00926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Homodimeric class 1 cytokine receptors include the erythropoietin (EPOR), thrombopoietin (TPOR), granulocyte colony-stimulating factor 3 (CSF3R), growth hormone (GHR), and prolactin receptors (PRLR). These cell-surface single-pass transmembrane (TM) glycoproteins regulate cell growth, proliferation, and differentiation and induce oncogenesis. An active TM signaling complex consists of a receptor homodimer, one or two ligands bound to the receptor extracellular domains, and two molecules of Janus Kinase 2 (JAK2) constitutively associated with the receptor intracellular domains. Although crystal structures of soluble extracellular domains with ligands have been obtained for all of the receptors except TPOR, little is known about the structure and dynamics of the complete TM complexes that activate the downstream JAK-STAT signaling pathway. Three-dimensional models of five human receptor complexes with cytokines and JAK2 were generated here by using AlphaFold Multimer. Given the large size of the complexes (from 3220 to 4074 residues), the modeling required a stepwise assembly from smaller parts, with selection and validation of the models through comparisons with published experimental data. The modeling of active and inactive complexes supports a general activation mechanism that involves ligand binding to a monomeric receptor followed by receptor dimerization and rotational movement of the receptor TM α-helices, causing proximity, dimerization, and activation of associated JAK2 subunits. The binding mode of two eltrombopag molecules to the TM α-helices of the active TPOR dimer was proposed. The models also help elucidate the molecular basis of oncogenic mutations that may involve a noncanonical activation route. Models equilibrated in explicit lipids of the plasma membrane are publicly available.
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Affiliation(s)
- Irina D Pogozheva
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Stanislav Cherepanov
- Biophysics Program, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Sang-Jun Park
- Departments of Biological Sciences and Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Malini Raghavan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Wonpil Im
- Departments of Biological Sciences and Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Andrei L Lomize
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
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4
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Lin RJ, Sutton J, Bentley T, Vargas-Inchaustegui DA, Nguyen D, Cheng HY, Yoon H, Van Blarcom TJ, Sasu BJ, Panowski SH, Sommer C. Constitutive Turbodomains enhance expansion and antitumor activity of allogeneic BCMA CAR T cells in preclinical models. SCIENCE ADVANCES 2023; 9:eadg8694. [PMID: 37540748 PMCID: PMC10403208 DOI: 10.1126/sciadv.adg8694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 07/05/2023] [Indexed: 08/06/2023]
Abstract
The magnitude of CAR T cell expansion has been associated with clinical efficacy. Although cytokines can augment CAR T cell proliferation, systemically administered cytokines can result in toxicities. To gain the benefits of cytokine signaling while mitigating toxicities, we designed constitutively active synthetic cytokine receptor chimeras (constitutive Turbodomains) that signal in a CAR T cell-specific manner. The modular design of Turbodomains enables diverse cytokine signaling outputs from a single homodimeric receptor chimera and allows multiplexing of different cytokine signals. Turbodomains containing an IL-2/15Rβ-derived signaling domain closely mimicked IL-15 signaling and enhanced CAR T cell potency. Allogeneic TurboCAR T cells targeting BCMA showed no evidence of aberrant proliferation yet displayed enhanced expansion and antitumor activity, prolonging survival and preventing extramedullary relapses in mouse models. These results illustrate the potential of constitutive Turbodomains to achieve selective potentiation of CAR T cells and demonstrate the safety and efficacy of allogeneic BCMA TurboCAR T cells, supporting clinical evaluation in multiple myeloma.
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Affiliation(s)
- Regina J. Lin
- Allogene Therapeutics Inc., 210 E. Grand Avenue, South San Francisco, CA 94080, USA
| | - Janette Sutton
- Allogene Therapeutics Inc., 210 E. Grand Avenue, South San Francisco, CA 94080, USA
| | - Trevor Bentley
- Allogene Therapeutics Inc., 210 E. Grand Avenue, South San Francisco, CA 94080, USA
| | | | - Duy Nguyen
- Allogene Therapeutics Inc., 210 E. Grand Avenue, South San Francisco, CA 94080, USA
| | - Hsin-Yuan Cheng
- Allogene Therapeutics Inc., 210 E. Grand Avenue, South San Francisco, CA 94080, USA
| | - Hayung Yoon
- Allogene Therapeutics Inc., 210 E. Grand Avenue, South San Francisco, CA 94080, USA
| | | | - Barbra J. Sasu
- Allogene Therapeutics Inc., 210 E. Grand Avenue, South San Francisco, CA 94080, USA
| | - Siler H. Panowski
- Allogene Therapeutics Inc., 210 E. Grand Avenue, South San Francisco, CA 94080, USA
| | - Cesar Sommer
- Allogene Therapeutics Inc., 210 E. Grand Avenue, South San Francisco, CA 94080, USA
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5
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Cai T, Lenoir Capello R, Pi X, Wu H, Chou JJ. Structural basis of γ chain family receptor sharing at the membrane level. Science 2023; 381:569-576. [PMID: 37535730 DOI: 10.1126/science.add1219] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 06/23/2023] [Indexed: 08/05/2023]
Abstract
Common γ chain (γc) cytokine receptors, including interleukin-2 (IL-2), IL-4, IL-7, IL-9, IL-15, and IL-21 receptors, are activated upon engagement with a common γc receptor (CD132) by concomitant binding of their ectodomains to an interleukin. In this work, we find that direct interactions between the transmembrane domains (TMDs) of both the γc and the interleukin receptors (ILRs) are also required for receptor activation. Moreover, the same γc TMD can specifically recognize multiple ILR TMDs of diverse sequences within the family. Heterodimer structures of γc TMD bound to IL-7 and IL-9 receptor TMDs-determined in a lipid bilayer-like environment by nuclear magnetic resonance spectroscopy-reveal a conserved knob-into-hole mechanism of recognition that mediates receptor sharing within the membrane. Thus, signaling in the γc receptor family requires specific heterotypic interactions of the TMDs.
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Affiliation(s)
- Tiantian Cai
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Rachel Lenoir Capello
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Xiong Pi
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Hao Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - James J Chou
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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6
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Pogozheva ID, Cherepanov S, Park SJ, Raghavan M, Im W, Lomize AL. Structural modeling of cytokine-receptor-JAK2 signaling complexes using AlphaFold Multimer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.14.544971. [PMID: 37398331 PMCID: PMC10312770 DOI: 10.1101/2023.06.14.544971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Homodimeric class 1 cytokine receptors include the erythropoietin (EPOR), thrombopoietin (TPOR), granulocyte colony-stimulating factor 3 (CSF3R), growth hormone (GHR), and prolactin receptors (PRLR). They are cell-surface single-pass transmembrane (TM) glycoproteins that regulate cell growth, proliferation, and differentiation and induce oncogenesis. An active TM signaling complex consists of a receptor homodimer, one or two ligands bound to the receptor extracellular domains and two molecules of Janus Kinase 2 (JAK2) constitutively associated with the receptor intracellular domains. Although crystal structures of soluble extracellular domains with ligands have been obtained for all the receptors except TPOR, little is known about the structure and dynamics of the complete TM complexes that activate the downstream JAK-STAT signaling pathway. Three-dimensional models of five human receptor complexes with cytokines and JAK2 were generated using AlphaFold Multimer. Given the large size of the complexes (from 3220 to 4074 residues), the modeling required a stepwise assembly from smaller parts with selection and validation of the models through comparisons with published experimental data. The modeling of active and inactive complexes supports a general activation mechanism that involves ligand binding to a monomeric receptor followed by receptor dimerization and rotational movement of the receptor TM α-helices causing proximity, dimerization, and activation of associated JAK2 subunits. The binding mode of two eltrombopag molecules to TM α-helices of the active TPOR dimer was proposed. The models also help elucidating the molecular basis of oncogenic mutations that may involve non-canonical activation route. Models equilibrated in explicit lipids of the plasma membrane are publicly available.
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Affiliation(s)
- Irina D. Pogozheva
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, United States
| | | | - Sang-Jun Park
- Departments of Biological Sciences and Chemistry, Lehigh University, Bethlehem, PA 18015, United States
| | - Malini Raghavan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Wonpil Im
- Departments of Biological Sciences and Chemistry, Lehigh University, Bethlehem, PA 18015, United States
| | - Andrei L. Lomize
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, United States
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7
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Muhammednazaar S, Yao J, Guo R, Rhee MS, Kim KH, Kang SG, Hong H. Lipid Bilayer Strengthens the Cooperative Network of a Membrane-Integral Enzyme. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.30.542905. [PMID: 37398072 PMCID: PMC10312574 DOI: 10.1101/2023.05.30.542905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Lipid bilayer provides a two-dimensional hydrophobic solvent milieu for membrane proteins in cells. Although the native bilayer is widely recognized as an optimal environment for folding and function of membrane proteins, the underlying physical basis remains elusive. Here, employing the intramembrane protease GlpG of Escherichia coli as a model, we elucidate how the bilayer stabilizes a membrane protein and engages the protein's residue interaction network compared to the nonnative hydrophobic medium, micelles. We find that the bilayer enhances GlpG stability by promoting residue burial in the protein interior compared to micelles. Strikingly, while the cooperative residue interactions cluster into multiple distinct regions in micelles, the whole packed regions of the protein act as a single cooperative unit in the bilayer. Molecular dynamics (MD) simulation indicates that lipids less efficiently solvate GlpG than detergents. Thus, the bilayerinduced enhancement of stability and cooperativity likely stems from the dominant intraprotein interactions outcompeting the weak lipid solvation. Our findings reveal a foundational mechanism in the folding, function, and quality control of membrane proteins. The enhanced cooperativity benefits function facilitating propagation of local structural perturbation across the membrane. However, the same phenomenon can render the proteins' conformational integrity vulnerable to missense mutations causing conformational diseases1,2.
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Affiliation(s)
| | - Jiaqi Yao
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Ruiqiong Guo
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - May S Rhee
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Kelly H Kim
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Seung-Gu Kang
- Computational Biology Center, IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598, USA
| | - Heedeok Hong
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
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8
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Desikan H, Kaur A, Pogozheva ID, Raghavan M. Effects of calreticulin mutations on cell transformation and immunity. J Cell Mol Med 2023; 27:1032-1044. [PMID: 36916035 PMCID: PMC10098294 DOI: 10.1111/jcmm.17713] [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: 11/04/2022] [Revised: 02/22/2023] [Accepted: 02/24/2023] [Indexed: 03/16/2023] Open
Abstract
Myeloproliferative neoplasms (MPNs) are cancers involving dysregulated production and function of myeloid lineage hematopoietic cells. Among MPNs, Essential thrombocythemia (ET), Polycythemia Vera (PV) and Myelofibrosis (MF), are driven by mutations that activate the JAK-STAT signalling pathway. Somatic mutations of calreticulin (CRT), an endoplasmic reticulum (ER)-localized lectin chaperone, are driver mutations in approximately 25% of ET and 35% of MF patients. The MPN-linked mutant CRT proteins have novel frameshifted carboxy-domain sequences and lack an ER retention motif, resulting in their secretion. Wild type CRT is a regulator of ER calcium homeostasis and plays a key role in the assembly of major histocompatibility complex (MHC) class I molecules, which are the ligands for antigen receptors of CD8+ T cells. Mutant CRT-linked oncogenesis results from the dysregulation of calcium signalling in cells and the formation of stable complexes of mutant CRT with myeloproliferative leukemia (MPL) protein, followed by downstream activation of the JAK-STAT signalling pathway. The intricate participation of CRT in ER protein folding, calcium homeostasis and immunity suggests the involvement of multiple mechanisms of mutant CRT-linked oncogenesis. In this review, we highlight recent findings related to the role of MPN-linked CRT mutations in the dysregulation of calcium homeostasis, MPL activation and immunity.
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Affiliation(s)
- Harini Desikan
- Department of Microbiology and ImmunologyUniversity of Michigan Medical SchoolAnn ArborMichiganUSA
| | - Amanpreet Kaur
- Department of Microbiology and ImmunologyUniversity of Michigan Medical SchoolAnn ArborMichiganUSA
| | - Irina D. Pogozheva
- Department of Medicinal ChemistryCollege of Pharmacy, University of MichiganAnn ArborMichiganUSA
| | - Malini Raghavan
- Department of Microbiology and ImmunologyUniversity of Michigan Medical SchoolAnn ArborMichiganUSA
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9
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Fu Y, Bedő J, Papenfuss AT, Rubin AF. Integrating deep mutational scanning and low-throughput mutagenesis data to predict the impact of amino acid variants. Gigascience 2022; 12:giad073. [PMID: 37721410 PMCID: PMC10506130 DOI: 10.1093/gigascience/giad073] [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: 02/14/2023] [Revised: 07/02/2023] [Accepted: 08/23/2023] [Indexed: 09/19/2023] Open
Abstract
BACKGROUND Evaluating the impact of amino acid variants has been a critical challenge for studying protein function and interpreting genomic data. High-throughput experimental methods like deep mutational scanning (DMS) can measure the effect of large numbers of variants in a target protein, but because DMS studies have not been performed on all proteins, researchers also model DMS data computationally to estimate variant impacts by predictors. RESULTS In this study, we extended a linear regression-based predictor to explore whether incorporating data from alanine scanning (AS), a widely used low-throughput mutagenesis method, would improve prediction results. To evaluate our model, we collected 146 AS datasets, mapping to 54 DMS datasets across 22 distinct proteins. CONCLUSIONS We show that improved model performance depends on the compatibility of the DMS and AS assays, and the scale of improvement is closely related to the correlation between DMS and AS results.
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Affiliation(s)
- Yunfan Fu
- The Walter and Eliza Hall Institute of Medical Research, Bioinformatics Division, 1G Royal Pde, Parkville, Victoria 3052, Australia
- The University of Melbourne, Department of Medical Biology, Parkville, Victoria 3010, Australia
| | - Justin Bedő
- The Walter and Eliza Hall Institute of Medical Research, Bioinformatics Division, 1G Royal Pde, Parkville, Victoria 3052, Australia
- The University of Melbourne, Department of Medical Biology, Parkville, Victoria 3010, Australia
| | - Anthony T Papenfuss
- The Walter and Eliza Hall Institute of Medical Research, Bioinformatics Division, 1G Royal Pde, Parkville, Victoria 3052, Australia
- The University of Melbourne, Department of Medical Biology, Parkville, Victoria 3010, Australia
- Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
| | - Alan F Rubin
- The Walter and Eliza Hall Institute of Medical Research, Bioinformatics Division, 1G Royal Pde, Parkville, Victoria 3052, Australia
- The University of Melbourne, Department of Medical Biology, Parkville, Victoria 3010, Australia
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10
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Varghese LN, Carreño-Tarragona G, Levy G, Gutiérrez-López de Ocáriz X, Rapado I, Martínez-López J, Ayala R, Constantinescu SN. MPL S505C enhances driver mutations at W515 in essential thrombocythemia. Blood Cancer J 2021; 11:188. [PMID: 34845187 PMCID: PMC8630145 DOI: 10.1038/s41408-021-00583-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/24/2021] [Accepted: 11/18/2021] [Indexed: 11/22/2022] Open
Affiliation(s)
- Leila N Varghese
- Université Catholique de Louvain and de Duve Institute, Brussels, Belgium.,Ludwig Institute for Cancer Research, Brussels, Belgium.,WELBIO (Walloon Excellence in Life Sciences and Biotechnology), Brussels, Belgium
| | - Gonzalo Carreño-Tarragona
- Haematology and Haemotherapy Department, Hospital Universitario 12 de Octubre, I+12, CNIO, Complutense University, CIBERONC, Madrid, Spain
| | - Gabriel Levy
- Université Catholique de Louvain and de Duve Institute, Brussels, Belgium.,Ludwig Institute for Cancer Research, Brussels, Belgium.,WELBIO (Walloon Excellence in Life Sciences and Biotechnology), Brussels, Belgium
| | - Xabier Gutiérrez-López de Ocáriz
- Haematology and Haemotherapy Department, Hospital Universitario 12 de Octubre, I+12, CNIO, Complutense University, CIBERONC, Madrid, Spain
| | - Inmaculada Rapado
- Haematology and Haemotherapy Department, Hospital Universitario 12 de Octubre, I+12, CNIO, Complutense University, CIBERONC, Madrid, Spain
| | - Joaquín Martínez-López
- Haematology and Haemotherapy Department, Hospital Universitario 12 de Octubre, I+12, CNIO, Complutense University, CIBERONC, Madrid, Spain
| | - Rosa Ayala
- Haematology and Haemotherapy Department, Hospital Universitario 12 de Octubre, I+12, CNIO, Complutense University, CIBERONC, Madrid, Spain.
| | - Stefan N Constantinescu
- Université Catholique de Louvain and de Duve Institute, Brussels, Belgium. .,Ludwig Institute for Cancer Research, Brussels, Belgium. .,WELBIO (Walloon Excellence in Life Sciences and Biotechnology), Brussels, Belgium. .,Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
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11
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Roy A, Shrivastva S, Naseer S. In and out: Traffic and dynamics of thrombopoietin receptor. J Cell Mol Med 2021; 25:9073-9083. [PMID: 34448528 PMCID: PMC8500957 DOI: 10.1111/jcmm.16878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/27/2021] [Accepted: 08/04/2021] [Indexed: 12/17/2022] Open
Abstract
Thrombopoiesis had long been a challenging area of study due to the rarity of megakaryocyte precursors in the bone marrow and the incomplete understanding of its regulatory cytokines. A breakthrough was achieved in the early 1990s with the discovery of the thrombopoietin receptor (TpoR) and its ligand thrombopoietin (TPO). This accelerated research in thrombopoiesis, including the uncovering of the molecular basis of myeloproliferative neoplasms (MPN) and the advent of drugs to treat thrombocytopenic purpura. TpoR mutations affecting its membrane dynamics or transport were increasingly associated with pathologies such as MPN and thrombocytosis. It also became apparent that TpoR affected hematopoietic stem cell (HSC) quiescence while priming hematopoietic stem cells (HSCs) towards the megakaryocyte lineage. Thorough knowledge of TpoR surface localization, dimerization, dynamics and stability is therefore crucial to understanding thrombopoiesis and related pathologies. In this review, we will discuss the mechanisms of TpoR traffic. We will focus on the recent progress in TpoR membrane dynamics and highlight the areas that remain unexplored.
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Affiliation(s)
- Anita Roy
- Kusuma School of Biological Sciences, Indian Institute of Technology, New Delhi, India
| | - Saurabh Shrivastva
- Kusuma School of Biological Sciences, Indian Institute of Technology, New Delhi, India
| | - Saadia Naseer
- Kusuma School of Biological Sciences, Indian Institute of Technology, New Delhi, India
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12
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Hitchcock IS, Hafer M, Sangkhae V, Tucker JA. The thrombopoietin receptor: revisiting the master regulator of platelet production. Platelets 2021; 32:770-778. [PMID: 34097561 PMCID: PMC8292222 DOI: 10.1080/09537104.2021.1925102] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 12/25/2022]
Abstract
Thrombopoietin (TPO) and its receptor, MPL, are the primary regulators of platelet production and critical for hematopoietic stem cell (HSC) maintenance. Since TPO was first cloned in 1994, the physiological and pathological roles of TPO and MPL have been well characterized, culminating in the first MPL agonists being approved for the treatment of chronic immune thrombocytopenia in 2008. Dysregulation of the TPO-MPL signaling axis contributes to the pathogenesis of hematological disorders: decreased expression or function results in severe thrombocytopenia progressing to bone marrow failure, while hyperactivation of MPL signaling, either by mutations in the receptor or associated Janus kinase 2 (JAK2), results in pathological myeloproliferation. Despite its importance, it was only recently that the long-running debate over the mechanism by which TPO binding activates MPL has been resolved. This review will cover key aspects of TPO and MPL structure and function and their importance in receptor activation, discuss how these are altered in hematological disorders and consider how a greater understanding could lead to the development of better-targeted and more efficacious therapies.
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Affiliation(s)
- Ian S. Hitchcock
- York Biomedical Research Institute, Department of Biology, University of York, York, UK
| | - Maximillian Hafer
- Department of Biology and Center of Cellular Nanoanalytics, University of Osnabrück, Osnabrück, Germany
| | - Veena Sangkhae
- Center for Iron Disorders, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Julie A. Tucker
- York Biomedical Research Institute, Department of Biology, University of York, York, UK
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13
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Väth K, Mattes C, Reinhard J, Covino R, Stumpf H, Hummer G, Ernst R. Cysteine cross-linking in native membranes establishes the transmembrane architecture of Ire1. J Cell Biol 2021; 220:212449. [PMID: 34196665 PMCID: PMC8256922 DOI: 10.1083/jcb.202011078] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 04/28/2021] [Accepted: 05/19/2021] [Indexed: 02/06/2023] Open
Abstract
The ER is a key organelle of membrane biogenesis and crucial for the folding of both membrane and secretory proteins. Sensors of the unfolded protein response (UPR) monitor the unfolded protein load in the ER and convey effector functions for maintaining ER homeostasis. Aberrant compositions of the ER membrane, referred to as lipid bilayer stress, are equally potent activators of the UPR. How the distinct signals from lipid bilayer stress and unfolded proteins are processed by the conserved UPR transducer Ire1 remains unknown. Here, we have generated a functional, cysteine-less variant of Ire1 and performed systematic cysteine cross-linking experiments in native membranes to establish its transmembrane architecture in signaling-active clusters. We show that the transmembrane helices of two neighboring Ire1 molecules adopt an X-shaped configuration independent of the primary cause for ER stress. This suggests that different forms of stress converge in a common, signaling-active transmembrane architecture of Ire1.
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Affiliation(s)
- Kristina Väth
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,Preclinical Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Carsten Mattes
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,Preclinical Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - John Reinhard
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,Preclinical Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Roberto Covino
- Frankfurt Institute of Advanced Sciences, Goethe-University, Frankfurt, Germany
| | - Heike Stumpf
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,Preclinical Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany.,Institute of Biophysics, Goethe-University, Frankfurt, Germany
| | - Robert Ernst
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,Preclinical Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
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14
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Functional Consequences of Mutations in Myeloproliferative Neoplasms. Hemasphere 2021; 5:e578. [PMID: 34095761 PMCID: PMC8171364 DOI: 10.1097/hs9.0000000000000578] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 04/13/2021] [Indexed: 01/14/2023] Open
Abstract
Driver mutations occur in Janus kinase 2 (JAK2), thrombopoietin receptor (MPL), and calreticulin (CALR) in BCR-ABL1 negative myeloproliferative neoplasms (MPNs). From mutations leading to one amino acid substitution in JAK2 or MPL, to frameshift mutations in CALR resulting in a protein with a different C-terminus, all the mutated proteins lead to pathologic and persistent JAK2-STAT5 activation. The most prevalent mutation, JAK2 V617F, is associated with the 3 entities polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis (MF), while CALR and MPL mutations are associated only with ET and MF. Triple negative ET and MF patients may harbor noncanonical mutations in JAK2 or MPL. One major fundamental question is whether the conformations of JAK2 V617F, MPL W515K/L/A, or CALR mutants differ from those of their wild type counterparts so that a specific treatment could target the clone carrying the mutated driver and spare physiological hematopoiesis. Of great interest, a set of epigenetic mutations can co-exist with the phenotypic driver mutations in 35%–40% of MPNs. These epigenetic mutations, such as TET2, EZH2, ASXL1, or DNMT3A mutations, promote clonal hematopoiesis and increased fitness of aged hematopoietic stem cells in both clonal hematopoiesis of indeterminate potential (CHIP) and MPNs. Importantly, the main MPN driver mutation JAK2 V617F is also associated with CHIP. Accumulation of several epigenetic and splicing mutations favors progression of MPNs to secondary acute myeloid leukemia. Another major fundamental question is how epigenetic rewiring due to these mutations interacts with persistent JAK2-STAT5 signaling. Answers to these questions are required for better therapeutic interventions aimed at preventing progression of ET and PV to MF, and transformation of these MPNs in secondary acute myeloid leukemia.
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15
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Venkatesan A, Geng J, Kandarpa M, Wijeyesakere SJ, Bhide A, Talpaz M, Pogozheva ID, Raghavan M. Mechanism of mutant calreticulin-mediated activation of the thrombopoietin receptor in cancers. J Cell Biol 2021; 220:212031. [PMID: 33909030 PMCID: PMC8085772 DOI: 10.1083/jcb.202009179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 02/10/2021] [Accepted: 03/17/2021] [Indexed: 12/21/2022] Open
Abstract
Myeloproliferative neoplasms (MPNs) are frequently driven by mutations within the C-terminal domain (C-domain) of calreticulin (CRT). CRTDel52 and CRTIns5 are recurrent mutations. Oncogenic transformation requires both mutated CRT and the thrombopoietin receptor (Mpl), but the molecular mechanism of CRT-mediated constitutive activation of Mpl is unknown. We show that the acquired C-domain of CRTDel52 mediates both Mpl binding and disulfide-linked CRTDel52 dimerization. Cysteine mutations within the novel C-domain (C400A and C404A) and the conserved N-terminal domain (N-domain; C163A) of CRTDel52 are required to reduce disulfide-mediated dimers and multimers of CRTDel52. Based on these data and published structures of CRT oligomers, we identify an N-domain dimerization interface relevant to both WT CRT and CRTDel52. Elimination of disulfide bonds and ionic interactions at both N-domain and C-domain dimerization interfaces is required to abrogate the ability of CRTDel52 to mediate cell proliferation via Mpl. Thus, MPNs exploit a natural dimerization interface of CRT combined with C-domain gain of function to achieve cell transformation.
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Affiliation(s)
- Arunkumar Venkatesan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI
| | - Jie Geng
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI
| | - Malathi Kandarpa
- Department of Internal Medicine/Division of Hematology/Oncology, University of Michigan Rogel Cancer Center, Ann Arbor, MI
| | | | - Ashwini Bhide
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI
| | - Moshe Talpaz
- Department of Internal Medicine/Division of Hematology/Oncology, University of Michigan Rogel Cancer Center, Ann Arbor, MI
| | - Irina D Pogozheva
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI
| | - Malini Raghavan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI
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16
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MPL mutations in essential thrombocythemia uncover a common path of activation with eltrombopag dependent on W491. Blood 2020; 135:948-953. [PMID: 31978223 DOI: 10.1182/blood.2019003240] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 01/10/2020] [Indexed: 12/26/2022] Open
Abstract
Mutations in the MPL gene encoding the human thrombopoietin receptor (TpoR) drive sporadic and familial essential thrombocythemias (ETs). We identified 2 ET patients harboring double mutations in cis in MPL, namely, L498W-H499C and H499Y-S505N. Using biochemical and signaling assays along with partial saturation mutagenesis, we showed that L498W is an activating mutation potentiated by H499C and that H499C and H499Y enhance the activity of the canonical S505N mutation. L498W and H499C can activate a truncated TpoR mutant, which lacks the extracellular domain, indicating these mutations act on the transmembrane (TM) cytosolic domain. Using a protein complementation assay, we showed that L498W and H499C strongly drive dimerization of TpoR. Activation by tryptophan substitution is exquisitely specific for position 498. Using structure-guided mutagenesis, we identified upstream amino acid W491 as a key residue required for activation by L498W or canonical activating mutations such as S505N and W515K, as well as by eltrombopag. Structural data point to a common dimerization and activation path for TpoR via its TM domain that is shared between the small-molecule agonist eltrombopag and canonical and novel activating TpoR mutations that all depend on W491, a potentially accessible extracellular residue that could become a target for therapeutic intervention.
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17
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Novel drivers and modifiers of MPL-dependent oncogenic transformation identified by deep mutational scanning. Blood 2020; 135:287-292. [PMID: 31697803 DOI: 10.1182/blood.2019002561] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 09/20/2019] [Indexed: 12/15/2022] Open
Abstract
The single transmembrane domain (TMD) of the human thrombopoietin receptor (TpoR/myeloproliferative leukemia [MPL] protein), encoded by exon 10 of the MPL gene, is a hotspot for somatic mutations associated with myeloproliferative neoplasms (MPNs). Approximately 6% and 14% of JAK2 V617F- essential thrombocythemia and primary myelofibrosis patients, respectively, have "canonical" MPL exon 10 driver mutations W515L/K/R/A or S505N, which generate constitutively active receptors and consequent loss of Tpo dependence. Other "noncanonical" MPL exon 10 mutations have also been identified in patients, both alone and in combination with canonical mutations, but, in almost all cases, their functional consequences and relevance to disease are unknown. Here, we used a deep mutational scanning approach to evaluate all possible single amino acid substitutions in the human TpoR TMD for their ability to confer cytokine-independent growth in Ba/F3 cells. We identified all currently recognized driver mutations and 7 novel mutations that cause constitutive TpoR activation, and a much larger number of second-site mutations that enhance S505N-driven activation. We found examples of both of these categories in published and previously unpublished MPL exon 10 sequencing data from MPN patients, demonstrating that some, if not all, of the new mutations reported here represent likely drivers or modifiers of myeloproliferative disease.
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18
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19
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Wilmes S, Hafer M, Vuorio J, Tucker JA, Winkelmann H, Löchte S, Stanly TA, Pulgar Prieto KD, Poojari C, Sharma V, Richter CP, Kurre R, Hubbard SR, Garcia KC, Moraga I, Vattulainen I, Hitchcock IS, Piehler J. Mechanism of homodimeric cytokine receptor activation and dysregulation by oncogenic mutations. Science 2020; 367:643-652. [PMID: 32029621 PMCID: PMC8117407 DOI: 10.1126/science.aaw3242] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 10/08/2019] [Accepted: 12/20/2019] [Indexed: 12/11/2022]
Abstract
Homodimeric class I cytokine receptors are assumed to exist as preformed dimers that are activated by ligand-induced conformational changes. We quantified the dimerization of three prototypic class I cytokine receptors in the plasma membrane of living cells by single-molecule fluorescence microscopy. Spatial and spatiotemporal correlation of individual receptor subunits showed ligand-induced dimerization and revealed that the associated Janus kinase 2 (JAK2) dimerizes through its pseudokinase domain. Oncogenic receptor and hyperactive JAK2 mutants promoted ligand-independent dimerization, highlighting the formation of receptor dimers as the switch responsible for signal activation. Atomistic modeling and molecular dynamics simulations based on a detailed energetic analysis of the interactions involved in dimerization yielded a mechanistic blueprint for homodimeric class I cytokine receptor activation and its dysregulation by individual mutations.
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Affiliation(s)
- Stephan Wilmes
- Department of Biology and Center of Cellular Nanoanalytics, University of Osnabrück, 49076 Osnabrück, Germany
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Maximillian Hafer
- Department of Biology and Center of Cellular Nanoanalytics, University of Osnabrück, 49076 Osnabrück, Germany
| | - Joni Vuorio
- Department of Physics, University of Helsinki, Helsinki, Finland
- Computational Physics Laboratory, Tampere University, Tampere, Finland
| | - Julie A Tucker
- York Biomedical Research Institute and Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Hauke Winkelmann
- Department of Biology and Center of Cellular Nanoanalytics, University of Osnabrück, 49076 Osnabrück, Germany
| | - Sara Löchte
- Department of Biology and Center of Cellular Nanoanalytics, University of Osnabrück, 49076 Osnabrück, Germany
| | - Tess A Stanly
- York Biomedical Research Institute and Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Katiuska D Pulgar Prieto
- York Biomedical Research Institute and Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Chetan Poojari
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Vivek Sharma
- Department of Physics, University of Helsinki, Helsinki, Finland
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Christian P Richter
- Department of Biology and Center of Cellular Nanoanalytics, University of Osnabrück, 49076 Osnabrück, Germany
| | - Rainer Kurre
- Department of Biology and Center of Cellular Nanoanalytics, University of Osnabrück, 49076 Osnabrück, Germany
| | - Stevan R Hubbard
- Skirball Institute and Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - K Christopher Garcia
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA
- Department of Molecular and Cellular Physiology and Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Ignacio Moraga
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, Helsinki, Finland.
- Computational Physics Laboratory, Tampere University, Tampere, Finland
| | - Ian S Hitchcock
- York Biomedical Research Institute and Department of Biology, University of York, Heslington, York YO10 5DD, UK.
| | - Jacob Piehler
- Department of Biology and Center of Cellular Nanoanalytics, University of Osnabrück, 49076 Osnabrück, Germany.
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20
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MPL membrane domain sequencing goes deep. Blood 2020; 135:236-237. [PMID: 31972012 DOI: 10.1182/blood.2019003482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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21
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Weinstein JY, Elazar A, Fleishman SJ. A lipophilicity-based energy function for membrane-protein modelling and design. PLoS Comput Biol 2019; 15:e1007318. [PMID: 31461441 PMCID: PMC6736313 DOI: 10.1371/journal.pcbi.1007318] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 09/10/2019] [Accepted: 08/01/2019] [Indexed: 01/14/2023] Open
Abstract
Membrane-protein design is an exciting and increasingly successful research area which has led to landmarks including the design of stable and accurate membrane-integral proteins based on coiled-coil motifs. Design of topologically more complex proteins, such as most receptors, channels, and transporters, however, demands an energy function that balances contributions from intra-protein contacts and protein-membrane interactions. Recent advances in water-soluble all-atom energy functions have increased the accuracy in structure-prediction benchmarks. The plasma membrane, however, imposes different physical constraints on protein solvation. To understand these constraints, we recently developed a high-throughput experimental screen, called dsTβL, and inferred apparent insertion energies for each amino acid at dozens of positions across the bacterial plasma membrane. Here, we express these profiles as lipophilicity energy terms in Rosetta and demonstrate that the new energy function outperforms previous ones in modelling and design benchmarks. Rosetta ab initio simulations starting from an extended chain recapitulate two-thirds of the experimentally determined structures of membrane-spanning homo-oligomers with <2.5Å root-mean-square deviation within the top-predicted five models (available online: http://tmhop.weizmann.ac.il). Furthermore, in two sequence-design benchmarks, the energy function improves discrimination of stabilizing point mutations and recapitulates natural membrane-protein sequences of known structure, thereby recommending this new energy function for membrane-protein modelling and design.
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Affiliation(s)
| | - Assaf Elazar
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Sarel Jacob Fleishman
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
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22
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Xie J, Chen X, Gao F, Hou R, Tian T, Zhang Y, Fan L, Hu J, Zhu G, Yang W, Wang H. Two activating mutations of MPL in triple-negative myeloproliferative neoplasms. Cancer Med 2019; 8:5254-5263. [PMID: 31294534 PMCID: PMC6718619 DOI: 10.1002/cam4.2387] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 05/24/2019] [Accepted: 06/17/2019] [Indexed: 12/17/2022] Open
Abstract
MPLW515K or W515L mutation plays an important role in the pathogenesis of myeloproliferative neoplasms (MPNs) through signaling molecules of the cytokine receptor axis. Besides MPLW515K or W515L, more than 30 atypical MPL mutations have been reported in patients who are negative for JAK2V617F, MPLW515K/L, and CALR mutations. Here, we aimed to identify the disease-causing mutations in the triple-negative case of ET. We described two MPL mutations in patients diagnosed with ET by target sequencing the hotspot mutation region of MPL gene. The MPLA497-L498ins4 is an insertion mutation detected recurrently in ET patients, and the MPLW515RQ516E is a novel double-point mutation found in an ET patient. Functional studies of MPLA497-L498ins4 and MPLW515RQ516E revealed that they are gain-of-function mutations. Mutants of MPLA497-L498ins4 and MPLW515RQ516E promoted autonomous proliferation on Ba/F3 cells in the absence of IL-3. Autonomous activation of TPO-R without ligand TPO was observed in MPLA497-L498ins4 and MPLW515RQ516E mutants. Lower percentage of cells in G1 phase and higher percentage of cells in S phase of two atypical MPL mutants were detected after culturing without any cytokines. These two atypical MPL mutations also presented increase in phosphorylation of signaling proteins including JAK2/STAT, PI3K/AKT, and MAPK/RAS. In summary, the MPLA497-L498ins4 and MPLW515RQ516E are gain-of-function mutations which may be novel driving factors participating in the pathogenesis of triple-negative MPN.
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Affiliation(s)
- Juan Xie
- Institute of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Xiuhua Chen
- Institute of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Feng Gao
- Clinical laboratory, The First Hospital of Shanxi Medical University, Taiyuan, China
| | - Ruixia Hou
- Institute of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Tingting Tian
- Institute of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Yaofang Zhang
- Institute of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Lifang Fan
- Institute of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Jinjun Hu
- Institute of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Guiyang Zhu
- Institute of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Wanfang Yang
- Institute of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Hongwei Wang
- Institute of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan, China
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23
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Vainchenker W, Plo I, Marty C, Varghese LN, Constantinescu SN. The role of the thrombopoietin receptor MPL in myeloproliferative neoplasms: recent findings and potential therapeutic applications. Expert Rev Hematol 2019; 12:437-448. [PMID: 31092065 DOI: 10.1080/17474086.2019.1617129] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Introduction: Classical Myeloproliferative Neoplasms (MPNs) include three disorders: Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF). MPNs are associated with constitutive activation of JAK2 leading to persistent cell signaling downstream of the dimeric myeloid cytokine receptors due to mutations in three genes encoding JAK2, calreticulin (CALR) and the thrombopoietin (TPO) receptor (MPL or TPOR). CALR and MPL mutants induce JAK2 activation that depends on MPL expression, thus explaining why they induce megakaryocyte pathologies including ET and PMF, but not PV. In contrast, JAK2 V617F drives all three diseases as it induces persistent signaling via EPOR, G-CSFR (CSF3R) and MPL. Areas Covered: Here, we review how different pathogenic mutations of MPL are translated into active receptors by inducing stable dimerization. We focus on the unique role of MPL on the hematopoietic stem cell (HSC), explaining why MPL is indispensable for the development of all MPNs. Last but not least, we describe how CALR mutants are pathogenic via binding and activation of MPL. Expert Opinion: Altogether, we believe that MPL is an important, but challenging, therapeutic target in MPNs that requires novel strategies to interrupt the specific conformational changes induced by each mutation or pathologic interaction without compromising the key functions of wild type MPL.
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Affiliation(s)
- William Vainchenker
- a UMR1170 , INSERM , Villejuif , France.,b Université Paris-Saclay , Villejuif , France
| | - Isabelle Plo
- a UMR1170 , INSERM , Villejuif , France.,b Université Paris-Saclay , Villejuif , France
| | - Caroline Marty
- a UMR1170 , INSERM , Villejuif , France.,b Université Paris-Saclay , Villejuif , France
| | - Leila N Varghese
- c Ludwig Institute for Cancer Research Brussels , Brussels , Belgium.,d de Duve Institute, Université catholique de Louvain , Brussels , Belgium
| | - Stefan N Constantinescu
- c Ludwig Institute for Cancer Research Brussels , Brussels , Belgium.,d de Duve Institute, Université catholique de Louvain , Brussels , Belgium.,e WELBIO (Walloon Excellence in Life Sciences and Biotechnology) , Brussels , Belgium
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24
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Floss DM, Scheller J. Naturally occurring and synthetic constitutive-active cytokine receptors in disease and therapy. Cytokine Growth Factor Rev 2019; 47:1-20. [PMID: 31147158 DOI: 10.1016/j.cytogfr.2019.05.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 05/15/2019] [Indexed: 02/07/2023]
Abstract
Cytokines control immune related events and are critically involved in a plethora of patho-physiological processes including autoimmunity and cancer development. Mutations which cause ligand-independent, constitutive activation of cytokine receptors are quite frequently found in diseases. Many constitutive-active cytokine receptor variants have been directly connected to disease development and mechanistically analyzed. Nature's solutions to generate constitutive cytokine receptors has been recently adopted by synthetic cytokine receptor biology, with the goal to optimize immune therapeutics. Here, CAR T cell immmunotherapy represents the first example to combine synthetic biology with genetic engineering during therapy. Hence, constitutive-active cytokine receptors are therapeutic targets, but also emerging tools to improve or modulate immunotherapeutic strategies. This review gives a comprehensive insight into the field of naturally occurring and synthetic constitutive-active cytokine receptors.
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Affiliation(s)
- Doreen M Floss
- Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany.
| | - Jürgen Scheller
- Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
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25
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Calreticulin mutants as oncogenic rogue chaperones for TpoR and traffic-defective pathogenic TpoR mutants. Blood 2019; 133:2669-2681. [PMID: 30902807 DOI: 10.1182/blood-2018-09-874578] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 03/12/2019] [Indexed: 01/22/2023] Open
Abstract
Calreticulin (CALR) +1 frameshift mutations in exon 9 are prevalent in myeloproliferative neoplasms. Mutant CALRs possess a new C-terminal sequence rich in positively charged amino acids, leading to activation of the thrombopoietin receptor (TpoR/MPL). We show that the new sequence endows the mutant CALR with rogue chaperone activity, stabilizing a dimeric state and transporting TpoR and mutants thereof to the cell surface in states that would not pass quality control; this function is absolutely required for oncogenic transformation. Mutant CALRs determine traffic via the secretory pathway of partially immature TpoR, as they protect N117-linked glycans from further processing in the Golgi apparatus. A number of engineered or disease-associated TpoRs such as TpoR/MPL R102P, which causes congenital thrombocytopenia, are rescued for traffic and function by mutant CALRs, which can also overcome endoplasmic reticulum retention signals on TpoR. In addition to requiring N-glycosylation of TpoR, mutant CALRs require a hydrophobic patch located in the extracellular domain of TpoR to induce TpoR thermal stability and initial intracellular activation, whereas full activation requires cell surface localization of TpoR. Thus, mutant CALRs are rogue chaperones for TpoR and traffic-defective TpoR mutants, a function required for the oncogenic effects.
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26
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Arai S, Shibazaki C, Adachi M, Maeda Y, Tahara T, Kato T, Miyazaki H, Kuroki R. The non-glycosylated N-terminal domain of human thrombopoietin is a molten globule under native conditions. FEBS J 2019; 286:1717-1733. [PMID: 30675759 DOI: 10.1111/febs.14765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 01/04/2019] [Accepted: 01/22/2019] [Indexed: 11/29/2022]
Abstract
Human thrombopoietin (hTPO) is a primary hematopoietic growth factor that regulates megakaryocytopoiesis and platelet production. The non-glycosylated form of 1-163 residues of hTPO (hTPO163 ) including the N-terminal active site domain (1-153 residues) is a candidate for treating thrombocytopenia. However, the autoantigenicity level of hTPO163 is higher than that of the full-length glycosylated hTPO (ghTPO332 ). In order to clarify the structural and physicochemical properties of hTPO163 , circular dichroism (CD) and differential scanning calorimetry (DSC) analyses were performed. CD analysis indicated that hTPO163 undergoes an induced-fit conformational change (+19.0% for helix and -16.7% for β-strand) upon binding to the neutralizing antibody TN1 in a manner similar to the coupled folding and binding mechanism. Moreover, DSC analysis showed that the thermal transition process of hTPO163 is a multistate transition; hTPO163 is thermally stabilized upon receptor (c-Mpl) binding, as indicated with raising the midpoint (Tm ) temperature of the transition by at least +9.5 K. The conformational variability and stability of hTPO163 indicate that hTPO163 exists as a molten globule under native conditions, which may enable the induced-fit conformational change according to the type of ligands (antibodies and receptor). Additionally, CD and computational analyses indicated that the C-terminal domain (154-332 residues) and glycosylation assists the folding of the N-terminal domain. These observations suggest that the antibody affinity and autoantigenicity of hTPO163 might be reduced, if the conformational variability of hTPO163 is restricted by mutation and/or by the addition of C-terminal domain with glycosylation to keep its conformation suitable for the c-Mpl recognition.
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Affiliation(s)
- Shigeki Arai
- Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology (QST), Tokai, Japan
| | - Chie Shibazaki
- Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology (QST), Tokai, Japan
| | - Motoyasu Adachi
- Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology (QST), Tokai, Japan
| | | | | | - Takashi Kato
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, Japan
| | | | - Ryota Kuroki
- Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Japan
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27
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Gorby C, Martinez-Fabregas J, Wilmes S, Moraga I. Mapping Determinants of Cytokine Signaling via Protein Engineering. Front Immunol 2018; 9:2143. [PMID: 30319612 PMCID: PMC6170656 DOI: 10.3389/fimmu.2018.02143] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 08/30/2018] [Indexed: 12/21/2022] Open
Abstract
Cytokines comprise a large family of secreted ligands that are critical for the regulation of immune homeostasis. Cytokines initiate signaling via dimerization or oligomerization of the cognate receptor subunits, triggering the activation of the Janus Kinases (JAKs)/ signal transducer and activator of transcription (STATs) pathway and the induction of specific gene expression programs and bioactivities. Deregulation of cytokines or their downstream signaling pathways are at the root of many human disorders including autoimmunity and cancer. Identifying and understanding the mechanistic principles that govern cytokine signaling will, therefore, be highly important in order to harness the therapeutic potential of cytokines. In this review, we will analyze how biophysical (ligand-receptor binding geometry and affinity) and cellular (receptor trafficking and intracellular abundance of signaling molecules) parameters shape the cytokine signalosome and cytokine functional pleiotropy; from the initial cytokine binding to its receptor to the degradation of the cytokine receptor complex in the proteasome and/or lysosome. We will also discuss how combining advanced protein engineering with detailed signaling and functional studies has opened promising avenues to tackle complex questions in the cytokine signaling field.
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Affiliation(s)
- Claire Gorby
- Division of Cell Signaling and Immunology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Jonathan Martinez-Fabregas
- Division of Cell Signaling and Immunology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Stephan Wilmes
- Division of Cell Signaling and Immunology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Ignacio Moraga
- Division of Cell Signaling and Immunology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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28
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Polyansky AA, Bocharov EV, Velghe AI, Kuznetsov AS, Bocharova OV, Urban AS, Arseniev AS, Zagrovic B, Demoulin JB, Efremov RG. Atomistic mechanism of the constitutive activation of PDGFRA via its transmembrane domain. Biochim Biophys Acta Gen Subj 2018; 1863:82-95. [PMID: 30253204 DOI: 10.1016/j.bbagen.2018.09.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 09/12/2018] [Accepted: 09/16/2018] [Indexed: 12/14/2022]
Abstract
Single-point mutations in the transmembrane (TM) region of receptor tyrosine kinases (RTKs) can lead to abnormal ligand-independent activation. We use a combination of computational modeling, NMR spectroscopy and cell experiments to analyze in detail the mechanism of how TM domains contribute to the activation of wild-type (WT) PDGFRA and its oncogenic V536E mutant. Using a computational framework, we scan all positions in PDGFRA TM helix for identification of potential functional mutations for the WT and the mutant and reveal the relationship between the receptor activity and TM dimerization via different interfaces. This strategy also allows us design a novel activating mutation in the WT (I537D) and a compensatory mutation in the V536E background eliminating its constitutive activity (S541G). We show both computationally and experimentally that single-point mutations in the TM region reshape the TM dimer ensemble and delineate the structural and dynamic determinants of spontaneous activation of PDGFRA via its TM domain. Our atomistic picture of the coupling between TM dimerization and PDGFRA activation corroborates the data obtained for other RTKs and provides a foundation for developing novel modulators of the pathological activity of PDGFRA.
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Affiliation(s)
- Anton A Polyansky
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, 16/10, 117997 Moscow, Russia; Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Campus Vienna Biocenter 5, A-1030 Vienna, Austria.
| | - Eduard V Bocharov
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, 16/10, 117997 Moscow, Russia; Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny, Moscow region 141700, Russia; National Research Centre "Kurchatov Institute", Akad. Kurchatova pl. 1, Moscow 123182, Russia
| | - Amélie I Velghe
- de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Andrey S Kuznetsov
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, 16/10, 117997 Moscow, Russia; Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny, Moscow region 141700, Russia; Higher School of Economics, Myasnitskaya 20, 101000 Moscow, Russia
| | - Olga V Bocharova
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, 16/10, 117997 Moscow, Russia; Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny, Moscow region 141700, Russia
| | - Anatoly S Urban
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, 16/10, 117997 Moscow, Russia; Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny, Moscow region 141700, Russia
| | - Alexander S Arseniev
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, 16/10, 117997 Moscow, Russia; Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny, Moscow region 141700, Russia
| | - Bojan Zagrovic
- Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Campus Vienna Biocenter 5, A-1030 Vienna, Austria
| | - Jean-Baptiste Demoulin
- de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium.
| | - Roman G Efremov
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, 16/10, 117997 Moscow, Russia; Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny, Moscow region 141700, Russia; Higher School of Economics, Myasnitskaya 20, 101000 Moscow, Russia
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29
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Ferrao RD, Wallweber HJ, Lupardus PJ. Receptor-mediated dimerization of JAK2 FERM domains is required for JAK2 activation. eLife 2018; 7:38089. [PMID: 30044226 PMCID: PMC6078494 DOI: 10.7554/elife.38089] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/24/2018] [Indexed: 12/11/2022] Open
Abstract
Cytokines and interferons initiate intracellular signaling via receptor dimerization and activation of Janus kinases (JAKs). How JAKs structurally respond to changes in receptor conformation induced by ligand binding is not known. Here, we present two crystal structures of the human JAK2 FERM and SH2 domains bound to Leptin receptor (LEPR) and Erythropoietin receptor (EPOR), which identify a novel dimeric conformation for JAK2. This 2:2 JAK2/receptor dimer, observed in both structures, identifies a previously uncharacterized receptor interaction essential to dimer formation that is mediated by a membrane-proximal peptide motif called the ‘switch’ region. Mutation of the receptor switch region disrupts STAT phosphorylation but does not affect JAK2 binding, indicating that receptor-mediated formation of the JAK2 FERM dimer is required for kinase activation. These data uncover the structural and molecular basis for how a cytokine-bound active receptor dimer brings together two JAK2 molecules to stimulate JAK2 kinase activity.
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Affiliation(s)
- Ryan D Ferrao
- Department of Structural Biology, Genentech, Inc., South San Francisco, United States
| | - Heidi Ja Wallweber
- Department of Structural Biology, Genentech, Inc., South San Francisco, United States
| | - Patrick J Lupardus
- Department of Structural Biology, Genentech, Inc., South San Francisco, United States
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30
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Abstract
Toll-like receptor 5 (TLR5) of mammals, birds, and reptiles detects bacterial flagellin and signals as a homodimeric complex. Structural studies using truncated TLR5b of zebrafish confirm the homodimeric TLR5-flagellin interaction. Here we provide evidence that zebrafish (Danio rerio) TLR5 unexpectedly signals as a heterodimer composed of the duplicated gene products drTLR5b and drTLR5a. Flagellin-induced signaling by the zebrafish TLR5 heterodimer increased in the presence of the TLR trafficking chaperone UNC93B1. Targeted exchange of drTLR5b and drTLR5a regions revealed that TLR5 activation needs a heterodimeric configuration of the receptor ectodomain and cytoplasmic domain, consistent with ligand-induced changes in receptor conformation. Structure-guided substitution of the presumed principal flagellin-binding site in human TLR5 with corresponding zebrafish TLR5 residues abrogated human TLR5 activation, indicating a species-specific TLR5-flagellin interaction. Our findings indicate that the duplicated TLR5 of zebrafish underwent subfunctionalization through concerted coevolution to form a unique heterodimeric flagellin receptor that operates fundamentally differently from TLR5 of other species.
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31
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Ramezanpour M, Lee J, Taneva SG, Tieleman DP, Cornell RB. An auto-inhibitory helix in CTP:phosphocholine cytidylyltransferase hijacks the catalytic residue and constrains a pliable, domain-bridging helix pair. J Biol Chem 2018. [PMID: 29519816 DOI: 10.1074/jbc.ra118.002053] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activity of CTP:phosphocholine cytidylyltransferase (CCT), a key enzyme in phosphatidylcholine synthesis, is regulated by reversible interactions of a lipid-inducible amphipathic helix (domain M) with membrane phospholipids. When dissociated from membranes, a portion of the M domain functions as an auto-inhibitory (AI) element to suppress catalysis. The AI helix from each subunit binds to a pair of α helices (αE) that extend from the base of the catalytic dimer to create a four-helix bundle. The bound AI helices make intimate contact with loop L2, housing a key catalytic residue, Lys122 The impacts of the AI helix on active-site dynamics and positioning of Lys122 are unknown. Extensive MD simulations with and without the AI helix revealed that backbone carbonyl oxygens at the point of contact between the AI helix and loop L2 can entrap the Lys122 side chain, effectively competing with the substrate, CTP. In silico, removal of the AI helices dramatically increased αE dynamics at a predicted break in the middle of these helices, enabling them to splay apart and forge new contacts with loop L2. In vitro cross-linking confirmed the reorganization of the αE element upon membrane binding of the AI helix. Moreover, when αE bending was prevented by disulfide engineering, CCT activation by membrane binding was thwarted. These findings suggest a novel two-part auto-inhibitory mechanism for CCT involving capture of Lys122 and restraint of the pliable αE helices. We propose that membrane binding enables bending of the αE helices, bringing the active site closer to the membrane surface.
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Affiliation(s)
- Mohsen Ramezanpour
- From the Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4 and
| | - Jaeyong Lee
- the Departments of Molecular Biology and Biochemistry and
| | | | - D Peter Tieleman
- From the Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4 and
| | - Rosemary B Cornell
- the Departments of Molecular Biology and Biochemistry and .,Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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32
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Anderson SM, Mueller BK, Lange EJ, Senes A. Combination of Cα-H Hydrogen Bonds and van der Waals Packing Modulates the Stability of GxxxG-Mediated Dimers in Membranes. J Am Chem Soc 2017; 139:15774-15783. [PMID: 29028318 PMCID: PMC5927632 DOI: 10.1021/jacs.7b07505] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The GxxxG motif is frequently found at the dimerization interface of a transmembrane structural motif called GASright, which is characterized by a short interhelical distance and a right-handed crossing angle between the helices. In GASright dimers, such as glycophorin A (GpA), BNIP3, and members of the ErbB family, the backbones of the helices are in contact, and they invariably display networks of 4 to 8 weak hydrogen bonds between Cα-H carbon donors and carbonyl acceptors on opposing helices (Cα-H···O═C hydrogen bonds). These networks of weak hydrogen bonds at the helix-helix interface are presumably stabilizing, but their energetic contribution to dimerization has yet to be determined experimentally. Here, we present a computational and experimental structure-based analysis of GASright dimers of different predicted stabilities, which show that a combination of van der Waals packing and Cα-H hydrogen bonding predicts the experimental trend of dimerization propensities. This finding provides experimental support for the hypothesis that the networks of Cα-H hydrogen bonds are major contributors to the free energy of association of GxxxG-mediated dimers. The structural comparison between groups of GASright dimers of different stabilities reveals distinct sequence as well as conformational preferences. Stability correlates with shorter interhelical distances, narrower crossing angles, better packing, and the formation of larger networks of Cα-H hydrogen bonds. The identification of these structural rules provides insight on how nature could modulate stability in GASright and finely tune dimerization to support biological function.
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Affiliation(s)
- Samantha M Anderson
- Department of Biochemistry, University of Wisconsin-Madison , 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - Benjamin K Mueller
- Department of Biochemistry, University of Wisconsin-Madison , 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - Evan J Lange
- Department of Biochemistry, University of Wisconsin-Madison , 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - Alessandro Senes
- Department of Biochemistry, University of Wisconsin-Madison , 433 Babcock Drive, Madison, Wisconsin 53706, United States
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33
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Araki M, Komatsu N. Novel molecular mechanism of cellular transformation by a mutant molecular chaperone in myeloproliferative neoplasms. Cancer Sci 2017; 108:1907-1912. [PMID: 28741795 PMCID: PMC5623763 DOI: 10.1111/cas.13327] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 07/19/2017] [Indexed: 12/03/2022] Open
Abstract
Deregulation of the cytokine‐receptor signaling pathway plays a significant role in tumorigenesis. Such deregulation is frequently caused by alterations in the genes involved in the signaling pathway. At the end of 2013, recurrent somatic mutations in the calreticulin (CALR) gene that encodes a molecular chaperone were identified in a subset of patients with Philadelphia‐chromosome negative myeloproliferative neoplasms (MPN). The present review focuses on the role of CALR mutations in the oncogenic transformations observed in MPN. All the CALR mutations were found to generate a + 1 frameshift in the reading frame on exon 9, which encodes the carboxy (C)‐terminus end of CALR, and thus conferred a common mutant‐specific sequence in all the CALR mutants. The mutant CALR (but not the wild‐type) constitutively activates the thrombopoietin (TPO) receptor, myeloproliferative leukemia protein (MPL), even in the absence of TPO to induce cellular transformation. Preferential interaction between the mutant CALR and MPL is achieved by a presumptive conformational change induced by the mutant‐specific C‐terminus domain, which allows N‐domain binding to MPL. Even though mutant CALR is expressed on the cell surface and is secreted out of cells, it only presents autocrine capacity for MPL activation. These findings define a novel molecular mechanism by which the mutant molecular chaperone constitutively activates the cytokine receptor to induce cellular transformation.
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Affiliation(s)
- Marito Araki
- Department of Transfusion Medicine and Stem Cell Regulation, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Norio Komatsu
- Department of Hematology, Juntendo University Graduate School of Medicine, Tokyo, Japan
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34
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An unusual, activating insertion/deletion MPL mutant in primary myelofibrosis. Leukemia 2017; 31:1838-1839. [PMID: 28529309 DOI: 10.1038/leu.2017.153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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35
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Rethinking JAK2 inhibition: towards novel strategies of more specific and versatile janus kinase inhibition. Leukemia 2017; 31:1023-1038. [DOI: 10.1038/leu.2017.43] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 12/16/2016] [Accepted: 01/10/2017] [Indexed: 12/19/2022]
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36
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Varghese LN, Defour JP, Pecquet C, Constantinescu SN. The Thrombopoietin Receptor: Structural Basis of Traffic and Activation by Ligand, Mutations, Agonists, and Mutated Calreticulin. Front Endocrinol (Lausanne) 2017; 8:59. [PMID: 28408900 PMCID: PMC5374145 DOI: 10.3389/fendo.2017.00059] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 03/17/2017] [Indexed: 12/13/2022] Open
Abstract
A well-functioning hematopoietic system requires a certain robustness and flexibility to maintain appropriate quantities of functional mature blood cells, such as red blood cells and platelets. This review focuses on the cytokine receptor that plays a significant role in thrombopoiesis: the receptor for thrombopoietin (TPO-R; also known as MPL). Here, we survey the work to date to understand how this receptor functions at a molecular level throughout its lifecycle, from traffic to the cell surface, dimerization and binding cognate cytokine via its extracellular domain, through to its subsequent activation of associated Janus kinases and initiation of downstream signaling pathways, as well as the regulation of these processes. Atomic level resolution structures of TPO-R have remained elusive. The identification of disease-causing mutations in the receptor has, however, offered some insight into structure and function relationships, as has artificial means of receptor activation, through TPO mimetics, transmembrane-targeting receptor agonists, and engineering in dimerization domains. More recently, a novel activation mechanism was identified whereby mutated forms of calreticulin form complexes with TPO-R via its extracellular N-glycosylated domain. Such complexes traffic pathologically in the cell and persistently activate JAK2, downstream signal transducers and activators of transcription (STATs), and other pathways. This pathologic TPO-R activation is associated with a large fraction of human myeloproliferative neoplasms.
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Affiliation(s)
- Leila N. Varghese
- Ludwig Institute for Cancer Research, Brussels Branch, Brussels, Belgium
- SIGN Pole, de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Jean-Philippe Defour
- Ludwig Institute for Cancer Research, Brussels Branch, Brussels, Belgium
- SIGN Pole, de Duve Institute, Université catholique de Louvain, Brussels, Belgium
- Department of Clinical Biology, Cliniques universitaires St Luc, Université catholique de Louvain, Brussels, Belgium
| | - Christian Pecquet
- Ludwig Institute for Cancer Research, Brussels Branch, Brussels, Belgium
- SIGN Pole, de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Stefan N. Constantinescu
- Ludwig Institute for Cancer Research, Brussels Branch, Brussels, Belgium
- SIGN Pole, de Duve Institute, Université catholique de Louvain, Brussels, Belgium
- *Correspondence: Stefan N. Constantinescu,
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37
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Deng W, Li R. Juxtamembrane contribution to transmembrane signaling. Biopolymers 2016; 104:317-22. [PMID: 25846274 DOI: 10.1002/bip.22651] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 03/23/2015] [Accepted: 03/30/2015] [Indexed: 12/11/2022]
Abstract
Signaling across the cell membrane mediated by transmembrane receptors plays an important role in diverse biological processes. Recent studies have indicated that, in a number of single-span transmembrane receptors, the intracellular juxtamembrane (JM) sequence linking the transmembrane helix with the rest of the cytoplasmic domain participates directly in the signaling process via several novel mechanisms. This review briefly highlights several modes of JM dynamics in the context of signal transduction that are shared by different types of transmembrane receptors.
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Affiliation(s)
- Wei Deng
- Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Emory University School of Medicine, Atlanta, GA, 30322
| | - Renhao Li
- Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Emory University School of Medicine, Atlanta, GA, 30322
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38
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Trenker R, Call MJ, Call ME. Progress and prospects for structural studies of transmembrane interactions in single-spanning receptors. Curr Opin Struct Biol 2016; 39:115-123. [DOI: 10.1016/j.sbi.2016.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 06/20/2016] [Accepted: 07/01/2016] [Indexed: 11/28/2022]
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39
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Screening for transmembrane association in divisome proteins using TOXGREEN, a high-throughput variant of the TOXCAT assay. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2573-2583. [PMID: 27453198 DOI: 10.1016/j.bbamem.2016.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Revised: 07/15/2016] [Accepted: 07/19/2016] [Indexed: 11/21/2022]
Abstract
TOXCAT is a widely used genetic assay to study interactions of transmembrane helices within the inner membrane of the bacterium Escherichia coli. TOXCAT is based on a fusion construct that links a transmembrane domain of interest with a cytoplasmic DNA-binding domain from the Vibrio cholerae ToxR protein. Interaction driven by the transmembrane domain results in dimerization of the ToxR domain, which, in turn, activates the expression of the reporter gene chloramphenicol acetyl transferase (CAT). Quantification of CAT is used as a measure of the ability of the transmembrane domain to self-associate. Because the quantification of CAT is relatively laborious, we developed a high-throughput variant of the assay, TOXGREEN, based on the expression of super-folded GFP and detection of fluorescence directly in unprocessed cell cultures. Careful side-by-side comparison of TOXCAT and TOXGREEN demonstrates that the methods have comparable response, dynamic range, sensitivity and intrinsic variability both in LB and minimal media. The greatly enhanced workflow makes TOXGREEN much more scalable and ideal for screening, since hundreds of constructs can be rapidly assessed in 96 well plates. Even for small scale investigations, TOXGREEN significantly reduces time, labor and cost associated with the procedure. We demonstrate applicability with a large screening for self-association among the transmembrane domains of bitopic proteins of the divisome (FtsL, FtsB, FtsQ, FtsI, FtsN, ZipA and EzrA) belonging to 11 bacterial species. The analysis confirms a previously reported tendency for FtsB to self-associate, and suggests that the transmembrane domains of ZipA, EzrA and FtsN may also possibly oligomerize.
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40
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Thrombopoietin receptor activation by myeloproliferative neoplasm associated calreticulin mutants. Blood 2016; 127:1325-35. [DOI: 10.1182/blood-2015-11-681932] [Citation(s) in RCA: 229] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 12/07/2015] [Indexed: 02/03/2023] Open
Abstract
Key Points
Calreticulin mutants responsible for myeloproliferative neoplasms specifically activate the thrombopoietin receptor and in turn JAK2. Activation of the thrombopoietin receptor requires the glycan binding site and a novel C-terminal tail of the mutant calreticulin.
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41
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Activation of the thrombopoietin receptor by mutant calreticulin in CALR-mutant myeloproliferative neoplasms. Blood 2016; 127:1307-16. [DOI: 10.1182/blood-2015-09-671172] [Citation(s) in RCA: 194] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 01/13/2016] [Indexed: 01/04/2023] Open
Abstract
Key Points
Mutant CALR induces TPO-independent growth in the human megakaryocytic cell line UT-7/TPO. Mutant CALR binds to the TPO receptor, inducing phosphorylation of JAK2 and activating downstream signaling.
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42
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Nespital T, van der Velden LM, Mensinga A, van der Vaart ED, Strous GJ. Fos-Zippered GH Receptor Cytosolic Tails Act as Jak2 Substrates and Signal Transducers. Mol Endocrinol 2016; 30:290-301. [PMID: 26859362 DOI: 10.1210/me.2015-1315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Members of the Janus kinase (Jak) family initiate the majority of downstream signaling events of the cytokine receptor family. The prevailing principle is that the receptors act in dimers: 2 Jak2 molecules bind to the cytosolic tails of a cytokine receptor family member and initiate Jak-signal transducer and activator of transcription signaling upon a conformational change in the receptor complex, induced by the cognate cytokine. Due to the complexity of signaling complexes, there is a strong need for in vitro model systems. To investigate the molecular details of the Jak2 interaction with the GH receptor (GHR), we used cytosolic tails provided with leucine zippers derived from c-Fos to mimic the dimerized state of GHR. Expressed together with Jak2, fos-zippered tails, but not unzippered tails, were stabilized. In addition, the Jak-signal transducer and activator of transcription signaling pathway was activated by the fos-zippered tails. The stabilization depended also on α-helix rotation of the zippers. Fos-zippered GHR tails and Jak2, both purified from baculovirus-infected insect cells, interacted via box1 with a binding affinity of approximately 40nM. As expected, the Jak kinase inhibitor Ruxolitinib inhibited the stabilization but did not affect the c-Fos-zippered GHR tail-Jak2 interaction. Analysis by blue-native gel electrophoresis revealed high molecular-weight complexes containing both Jak2 and nonphosphorylated GHR tails, whereas Jak2-dissociated tails were highly phosphorylated and monomeric, implying that Jak2 detaches from its substrate upon phosphorylation.
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Affiliation(s)
- Tobias Nespital
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Lieke M van der Velden
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Anneloes Mensinga
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Elisabeth D van der Vaart
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Ger J Strous
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
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43
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Leroy E, Defour JP, Sato T, Dass S, Gryshkova V, Shwe MM, Staerk J, Constantinescu SN, Smith SO. His499 Regulates Dimerization and Prevents Oncogenic Activation by Asparagine Mutations of the Human Thrombopoietin Receptor. J Biol Chem 2015; 291:2974-87. [PMID: 26627830 DOI: 10.1074/jbc.m115.696534] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Indexed: 01/18/2023] Open
Abstract
Ligand binding to the extracellular domain of the thrombopoietin receptor (TpoR) imparts a specific orientation on the transmembrane (TM) and intracellular domains of the receptors that is required for physiologic activation via receptor dimerization. To map the inactive and active dimeric orientations of the TM helices, we performed asparagine (Asn)-scanning mutagenesis of the TM domains of the murine and human TpoR. Substitution of Asn at only one position (S505N) activated the human receptor, whereas Asn substitutions at several positions activated the murine receptor. Second site mutational studies indicate that His(499) near the N terminus of the TM domain is responsible for protecting the human receptor from activation by Asn mutations. Structural studies reveal that the sequence preceding His(499) is helical in the murine receptor but non-helical in peptides corresponding to the TM domain of the inactive human receptor. The activating S505N mutation and the small molecule agonist eltrombopag both induce helix in this region of the TM domain and are associated with dimerization and activation of the human receptor. Thus, His(499) regulates the activation of human TpoR and provides additional protection against activating mutations, such as oncogenic Asn mutations in the TM domain.
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Affiliation(s)
- Emilie Leroy
- From the Ludwig Institute for Cancer Research, 1200 Brussels, Belgium de Duve Institute, Université catholique de Louvain, 1200 Brussels, Belgium
| | - Jean-Philippe Defour
- From the Ludwig Institute for Cancer Research, 1200 Brussels, Belgium de Duve Institute, Université catholique de Louvain, 1200 Brussels, Belgium
| | - Takeshi Sato
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Sharmila Dass
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794-5215, and
| | - Vitalina Gryshkova
- From the Ludwig Institute for Cancer Research, 1200 Brussels, Belgium de Duve Institute, Université catholique de Louvain, 1200 Brussels, Belgium
| | - Myat M Shwe
- From the Ludwig Institute for Cancer Research, 1200 Brussels, Belgium de Duve Institute, Université catholique de Louvain, 1200 Brussels, Belgium
| | - Judith Staerk
- Stem Cell Group, Nordic European Molecular Biology Laboratory Partnership and Center for Molecular Medicine, 0318 Oslo, Norway
| | - Stefan N Constantinescu
- From the Ludwig Institute for Cancer Research, 1200 Brussels, Belgium de Duve Institute, Université catholique de Louvain, 1200 Brussels, Belgium,
| | - Steven O Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794-5215, and
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44
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Li Q, Wong YL, Yueqi Lee M, Li Y, Kang C. Solution structure of the transmembrane domain of the mouse erythropoietin receptor in detergent micelles. Sci Rep 2015; 5:13586. [PMID: 26316120 PMCID: PMC4551963 DOI: 10.1038/srep13586] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 07/31/2015] [Indexed: 12/19/2022] Open
Abstract
Erythropoiesis is regulated by the erythropoietin receptor (EpoR) binding to its ligand. The transmembrane domain (TMD) and the juxtamembrane (JM) regions of the EpoR are important for signal transduction across the cell membrane. We report a solution NMR study of the mouse erythropoietin receptor (mEpoR) comprising the TMD and the JM regions reconstituted in dodecylphosphocholine (DPC) micelles. The TMD and the C-terminal JM region of the mEpoR are mainly α-helical, adopting a similar structure to those of the human EpoR. Residues from S216 to T219 in mEpoR form a short helix. Relaxation study demonstrates that the TMD of the mEpoR is rigid whilst the N-terminal region preceding the TMD is flexible. Fluorescence spectroscopy and sequence analysis indicate that the C-terminal JM region is exposed to the solvent. Helix wheel result shows that there is hydrophilic patch in the TMD of the mEpoR formed by residues S231, S238 and T242, and these residues might be important for the receptor dimerization.
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Affiliation(s)
- Qingxin Li
- Institute of Chemical &Engineering Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Ying Lei Wong
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR), Singapore, 138669 Singapore
| | - Michelle Yueqi Lee
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR), Singapore, 138669 Singapore
| | - Yan Li
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR), Singapore, 138669 Singapore
| | - CongBao Kang
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR), Singapore, 138669 Singapore
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45
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Maruyama IN. Activation of transmembrane cell-surface receptors via a common mechanism? The "rotation model". Bioessays 2015; 37:959-67. [PMID: 26241732 PMCID: PMC5054922 DOI: 10.1002/bies.201500041] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
It has long been thought that transmembrane cell-surface receptors, such as receptor tyrosine kinases and cytokine receptors, among others, are activated by ligand binding through ligand-induced dimerization of the receptors. However, there is growing evidence that prior to ligand binding, various transmembrane receptors have a preformed, yet inactive, dimeric structure on the cell surface. Various studies also demonstrate that during transmembrane signaling, ligand binding to the extracellular domain of receptor dimers induces a rotation of transmembrane domains, followed by rearrangement and/or activation of intracellular domains. The paper here describes transmembrane cell-surface receptors that are known or proposed to exist in dimeric form prior to ligand binding, and discusses how these preformed dimers are activated by ligand binding.
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Affiliation(s)
- Ichiro N Maruyama
- Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
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46
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Li Q, Wong YL, Huang Q, Kang C. Structural insight into the transmembrane domain and the juxtamembrane region of the erythropoietin receptor in micelles. Biophys J 2015; 107:2325-36. [PMID: 25418301 DOI: 10.1016/j.bpj.2014.10.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 10/13/2014] [Accepted: 10/15/2014] [Indexed: 01/06/2023] Open
Abstract
Erythropoietin receptor (EpoR) dimerization is an important step in erythrocyte formation. Its transmembrane domain (TMD) and juxtamembrane (JM) region are essential for signal transduction across the membrane. A construct compassing residues S212-P259 and containing the TMD and JM region of the human EpoR was purified and reconstituted in detergent micelles. The solution structure of the construct was determined in dodecylphosphocholine (DPC) micelles by solution NMR spectroscopy. Structural and dynamic studies demonstrated that the TMD and JM region are an ?-helix in DPC micelles, whereas residues S212-D224 at the N-terminus of the construct are not structured. The JM region is a helix that contains a hydrophobic patch formed by conserved hydrophobic residues (L253, I257, and W258). Nuclear Overhauser effect analysis, fluorescence spectroscopy, and paramagnetic relaxation enhancement experiments suggested that the JM region is exposed to the solvent. The structures of the TMD and JM region of the mouse EpoR were similar to those of the human EpoR.
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Affiliation(s)
- Qingxin Li
- Institute of Chemical & Engineering Sciences, Technology and Research (A(?)STAR), Singapore
| | - Ying Lei Wong
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A(?)STAR), Singapore
| | - Qiwei Huang
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A(?)STAR), Singapore
| | - CongBao Kang
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A(?)STAR), Singapore.
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47
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Waters M, Brooks A. JAK2 activation by growth hormone and other cytokines. Biochem J 2015; 466:1-11. [PMID: 25656053 PMCID: PMC4325515 DOI: 10.1042/bj20141293] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 11/17/2014] [Accepted: 11/24/2014] [Indexed: 12/30/2022]
Abstract
Growth hormone (GH) and structurally related cytokines regulate a great number of physiological and pathological processes. They do this by coupling their single transmembrane domain (TMD) receptors to cytoplasmic tyrosine kinases, either as homodimers or heterodimers. Recent studies have revealed that many of these receptors exist as constitutive dimers rather than being dimerized as a consequence of ligand binding, which has necessitated a new paradigm for describing their activation process. In the present study, we describe a model for activation of the tyrosine kinase Janus kinase 2 (JAK2) by the GH receptor homodimer based on biochemical data and molecular dynamics simulations. Binding of the bivalent ligand reorientates and rotates the receptor subunits, resulting in a transition from a form with parallel TMDs to one where the TMDs separate at the point of entry into the cytoplasm. This movement slides the pseudokinase inhibitory domain of one JAK kinase away from the kinase domain of the other JAK within the receptor dimer-JAK complex, allowing the two kinase domains to interact and trans-activate. This results in phosphorylation and activation of STATs and other signalling pathways linked to this receptor which then regulate postnatal growth, metabolism and stem cell activation. We believe that this model will apply to most if not all members of the class I cytokine receptor family, and will be useful in the design of small antagonists and agonists of therapeutic value.
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Key Words
- class i cytokine receptors
- cytokine receptor signalling
- growth hormone
- growth hormone receptor
- janus kinase 2 (jak2)
- srk family kinases
- cntf, ciliary neurotropic factor
- crh, cytokine receptor homology
- ct-1, cardiotropin-1
- ecd, extracellular domain
- epo, erythropoietin
- fniii, fibronectin iii-like
- gh, growth hormone
- gm-csf, granulocyte-macrophage colony-stimulating factor
- jak, janus kinase
- jm, juxtamembrane
- mab, monoclonal antibody
- osm, oncostatin-m
- pk, pseudokinase
- tmd, transmembrane domain
- tpo, thrombopoietin
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Affiliation(s)
- Michael J. Waters
- *Institute for Molecular Bioscience, The University of Queensland Institute, QLD 4072, Australia
| | - Andrew J. Brooks
- *Institute for Molecular Bioscience, The University of Queensland Institute, QLD 4072, Australia
- †The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, QLD 4072, Australia
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48
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The thrombopoietin receptor P106L mutation functionally separates receptor signaling activity from thrombopoietin homeostasis. Blood 2014; 125:1159-69. [PMID: 25538044 DOI: 10.1182/blood-2014-07-587170] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The interaction between thrombopoietin (THPO) and its receptor c-Mpl regulates downstream cytokine signaling and platelet homeostasis. Hereditary mutations of c-Mpl can either result in loss-of-function and thrombocytopenia or in gain-of-function and thrombocythemia (HT), and are important models to analyze the mechanism of c-Mpl activity. We have analyzed the effect of the c-Mpl P106L gain-of-function and the nearby loss-of-function R102P and F104S mutations, which cause HT or thrombocytopenia, respectively, on posttranslational processing, intracellular trafficking, cell surface expression, and cell proliferation. In contrast to R102P and F104S, the P106L mutant confers cytokine-independent growth and stimulates downstream signaling after THPO treatment in Ba/F3 cells. Despite their opposite function, R102P and P106L, both lead to abnormal subcellular receptor distribution, lack of membrane localization, impaired glycosylation, and elevated THPO serum levels in effected patients. These findings indicate that the activation of downstream signaling by c-Mpl P106L does not require correct processing, trafficking, and cell surface expression of c-Mpl, whereas the negative feedback loop controlling THPO serum levels requires cell surface expression of the receptor. Thus, we propose that the P106L mutation functionally separates the activity of c-Mpl in downstream signaling from that in maintaining platelet homeostasis.
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49
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Waters MJ, Brooks AJ, Chhabra Y. A new mechanism for growth hormone receptor activation of JAK2, and implications for related cytokine receptors. JAKSTAT 2014; 3:e29569. [PMID: 25101218 PMCID: PMC4119067 DOI: 10.4161/jkst.29569] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 06/11/2014] [Accepted: 06/12/2014] [Indexed: 11/25/2022] Open
Abstract
The growth hormone receptor was the first cytokine receptor to be cloned and crystallized, and provides a valuable exemplar for activation of its cognate kinase, JAK2. We review progress in understanding its activation mechanism, in particular the molecular movements made by this constitutively dimerized receptor in response to ligand binding, and how these lead to a separation of JAK-binding Box1 motifs. Such a separation leads to removal of the pseudokinase inhibitory domain from the kinase domain of a partner JAK2 bound to the receptor, and vice versa, leading to apposition of the kinase domains and transactivation. This may be a general mechanism for class I cytokine receptor action.
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Affiliation(s)
- Michael J Waters
- Institute for Molecular Bioscience; The University of Queensland; St. Lucia, QLD Australia
| | - Andrew J Brooks
- Institute for Molecular Bioscience; The University of Queensland; St. Lucia, QLD Australia
| | - Yash Chhabra
- Institute for Molecular Bioscience; The University of Queensland; St. Lucia, QLD Australia
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50
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Brooks AJ, Dai W, O'Mara ML, Abankwa D, Chhabra Y, Pelekanos RA, Gardon O, Tunny KA, Blucher KM, Morton CJ, Parker MW, Sierecki E, Gambin Y, Gomez GA, Alexandrov K, Wilson IA, Doxastakis M, Mark AE, Waters MJ. Mechanism of activation of protein kinase JAK2 by the growth hormone receptor. Science 2014; 344:1249783. [PMID: 24833397 DOI: 10.1126/science.1249783] [Citation(s) in RCA: 280] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Signaling from JAK (Janus kinase) protein kinases to STAT (signal transducers and activators of transcription) transcription factors is key to many aspects of biology and medicine, yet the mechanism by which cytokine receptors initiate signaling is enigmatic. We present a complete mechanistic model for activation of receptor-bound JAK2, based on an archetypal cytokine receptor, the growth hormone receptor. For this, we used fluorescence resonance energy transfer to monitor positioning of the JAK2 binding motif in the receptor dimer, substitution of the receptor extracellular domains with Jun zippers to control the position of its transmembrane (TM) helices, atomistic modeling of TM helix movements, and docking of the crystal structures of the JAK2 kinase and its inhibitory pseudokinase domain with an opposing kinase-pseudokinase domain pair. Activation of the receptor dimer induced a separation of its JAK2 binding motifs, driven by a ligand-induced transition from a parallel TM helix pair to a left-handed crossover arrangement. This separation leads to removal of the pseudokinase domain from the kinase domain of the partner JAK2 and pairing of the two kinase domains, facilitating trans-activation. This model may well generalize to other class I cytokine receptors.
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Affiliation(s)
- Andrew J Brooks
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia.
| | - Wei Dai
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77004, USA
| | - Megan L O'Mara
- The University of Queensland, School of Chemistry and Molecular Biosciences, St Lucia, Queensland 4072, Australia
| | - Daniel Abankwa
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Yash Chhabra
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Rebecca A Pelekanos
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Olivier Gardon
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Kathryn A Tunny
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Kristopher M Blucher
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Craig J Morton
- Biota Structural Biology Laboratory and Australian Cancer Research Foundation (ACRF) Rational Drug Discovery Centre, St Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - Michael W Parker
- Biota Structural Biology Laboratory and Australian Cancer Research Foundation (ACRF) Rational Drug Discovery Centre, St Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia. Department of Biochemistry and Molecular Biology and Bio21 Institute, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Emma Sierecki
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Yann Gambin
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Guillermo A Gomez
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Kirill Alexandrov
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Ian A Wilson
- Scripps Research Institute, La Jolla, CA 92037, USA
| | - Manolis Doxastakis
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77004, USA
| | - Alan E Mark
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia. The University of Queensland, School of Chemistry and Molecular Biosciences, St Lucia, Queensland 4072, Australia
| | - Michael J Waters
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia.
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