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Elad N, De Strooper B, Lismont S, Hagen W, Veugelen S, Arimon M, Horré K, Berezovska O, Sachse C, Chávez-Gutiérrez L. The dynamic conformational landscape of gamma-secretase. J Cell Sci 2016; 128:589-98. [PMID: 25501811 PMCID: PMC4311135 DOI: 10.1242/jcs.164384] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The structure and function of the gamma-secretase proteases are of great interest because of their crucial roles in cellular and disease processes. We established a novel purification protocol for the gamma-secretase complex that involves a conformation- and complex-specific nanobody, yielding highly pure and active enzyme. Using single particle electron microscopy, we analyzed the gamma-secretase structure and its conformational variability. Under steady-state conditions, the complex adopts three major conformations, which differ in overall compactness and relative position of the nicastrin ectodomain. Occupancy of the active or substrate-binding sites by inhibitors differentially stabilizes subpopulations of particles with compact conformations, whereas a mutation linked to familial Alzheimer disease results in enrichment of extended-conformation complexes with increased flexibility. Our study presents the csecretase complex as a dynamic population of interconverting conformations, involving rearrangements at the nanometer scale and a high level of structural interdependence between subunits. The fact that protease inhibition or clinical mutations, which affect amyloid beta (Abeta) generation, enrich for particular subpopulations of conformers indicates the functional relevance of the observed dynamic changes, which are likely to be instrumental for highly allosteric behavior of the enzyme.
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Affiliation(s)
- Nadav Elad
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium
- Center of Human Genetics, University Hospitals Leuven & Department of Human Genetics, KU Leuven, and Leuven Research Institute for Neuroscience and Disease (LIND), 3000 Leuven, Belgium
| | - Bart De Strooper
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium
- Center of Human Genetics, University Hospitals Leuven & Department of Human Genetics, KU Leuven, and Leuven Research Institute for Neuroscience and Disease (LIND), 3000 Leuven, Belgium
- UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
- Authors for correspondence (; ; )
| | - Sam Lismont
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium
- Center of Human Genetics, University Hospitals Leuven & Department of Human Genetics, KU Leuven, and Leuven Research Institute for Neuroscience and Disease (LIND), 3000 Leuven, Belgium
| | - Wim Hagen
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Meyerhofstrasse1, 69117 Heidelberg, Germany
| | - Sarah Veugelen
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium
- Center of Human Genetics, University Hospitals Leuven & Department of Human Genetics, KU Leuven, and Leuven Research Institute for Neuroscience and Disease (LIND), 3000 Leuven, Belgium
| | - Muriel Arimon
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Katrien Horré
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium
- Center of Human Genetics, University Hospitals Leuven & Department of Human Genetics, KU Leuven, and Leuven Research Institute for Neuroscience and Disease (LIND), 3000 Leuven, Belgium
| | - Oksana Berezovska
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Meyerhofstrasse1, 69117 Heidelberg, Germany
| | - Carsten Sachse
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Meyerhofstrasse1, 69117 Heidelberg, Germany
- Authors for correspondence (; ; )
| | - Lucía Chávez-Gutiérrez
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium
- Center of Human Genetics, University Hospitals Leuven & Department of Human Genetics, KU Leuven, and Leuven Research Institute for Neuroscience and Disease (LIND), 3000 Leuven, Belgium
- Authors for correspondence (; ; )
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102
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Dries DR, Zhu Y, Brooks MM, Forero DA, Adachi M, Cenik B, West JM, Han YH, Yu C, Arbella J, Nordin A, Adolfsson R, Del-Favero J, Lu QR, Callaerts P, Birnbaum SG, Yu G. Loss of Nicastrin from Oligodendrocytes Results in Hypomyelination and Schizophrenia with Compulsive Behavior. J Biol Chem 2016; 291:11647-56. [PMID: 27008863 DOI: 10.1074/jbc.m116.715078] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Indexed: 12/12/2022] Open
Abstract
The biological underpinnings and the pathological lesions of psychiatric disorders are centuries-old questions that have yet to be understood. Recent studies suggest that schizophrenia and related disorders likely have their origins in perturbed neurodevelopment and can result from a large number of common genetic variants or multiple, individually rare genetic alterations. It is thus conceivable that key neurodevelopmental pathways underline the various genetic changes and the still unknown pathological lesions in schizophrenia. Here, we report that mice defective of the nicastrin subunit of γ-secretase in oligodendrocytes have hypomyelination in the central nervous system. These mice have altered dopamine signaling and display profound abnormal phenotypes reminiscent of schizophrenia. In addition, we identify an association of the nicastrin gene with a human schizophrenia cohort. These observations implicate γ-secretase and its mediated neurodevelopmental pathways in schizophrenia and provide support for the "myelination hypothesis" of the disease. Moreover, by showing that schizophrenia and obsessive-compulsive symptoms could be modeled in animals wherein a single genetic factor is altered, our work provides a biological basis that schizophrenia with obsessive-compulsive disorder is a distinct subtype of schizophrenia.
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Affiliation(s)
- Daniel R Dries
- From the Departments of Neuroscience, the Chemistry Department, Juniata College, Huntingdon, Pennsylvania 16652
| | - Yi Zhu
- From the Departments of Neuroscience
| | | | - Diego A Forero
- the Laboratory of NeuroPsychiatric Genetics, Biomedical Sciences Research Group, School of Medicine, Universidad Antonio Nariño, 37-94 Bogotá, Colombia
| | | | | | | | | | - Cong Yu
- From the Departments of Neuroscience
| | - Jennifer Arbella
- the Chemistry Department, Juniata College, Huntingdon, Pennsylvania 16652
| | - Annelie Nordin
- the Division of Psychiatry, Department of Clinical Sciences, Umea University, SE-901 87 Umea, Sweden
| | - Rolf Adolfsson
- the Division of Psychiatry, Department of Clinical Sciences, Umea University, SE-901 87 Umea, Sweden
| | - Jurgen Del-Favero
- the Applied Molecular Genomics Unit, VIB Department of Molecular Genetics, University of Antwerp, 2610 Antwerp, Belgium
| | - Q Richard Lu
- the Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, and Developmental Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Patrick Callaerts
- the Laboratory of Behavioral and Developmental Genetics, Katholieke Universiteit Leuven Center for Human Genetics, VIB Center for the Biology of Disease, 3000 Leuven, Belgium
| | | | - Gang Yu
- From the Departments of Neuroscience,
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103
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Zhang X, Sullivan E, Scimeca M, Wu X, Li YM, Sisodia SS. Evidence That the "Lid" Domain of Nicastrin Is Not Essential for Regulating γ-Secretase Activity. J Biol Chem 2016; 291:6748-53. [PMID: 26887941 DOI: 10.1074/jbc.c115.701649] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Indexed: 11/06/2022] Open
Abstract
Understanding of the structure of the γ-secretase complex consisting of presenilin (PS), anterior pharynx-defective 1 (APH-1), nicastrin (NCT), and presenilin enhancer 2 (PEN-2) is of significant therapeutic interest for the design of γ-secretase modulators for Alzheimer disease. The structure of γ-secretase revealed by cryo-EM approaches suggested a substrate binding mechanism for NCT, a bilobar structure that involved rotation of the two lobes around a central pivot and opening of a "lid" region that facilitates substrate recruitment. To validate this proposal, we expressed NCT that lacks the lid entirely, or a variety of NCT variants that harbor mutations at highly conserved residues in the lid region inNCT-deficient cells, and then assessed their impact on γ-secretase assembly, activity, and stability. In addition, we assessed the impact of mutating a critical residue proposed to be a pivot around which the two lobes of NCT rotate. Our results show that neither the mutations on the lid tested here nor the entire lid deletion has any significant impact on γ-secretase assembly, activity, and stability, and that NCT with the mutation of the proposed pivot rescues γ-secretase activity inNCT-deficient cells in a manner indistinguishable from WT NCT. These findings indicate that the NCT lid is not an essential element necessary for γ-secretase assembly, activity, and stability, and that rotation of the two lobes appears not to be a prerequisite for substrate binding and γ-secretase function.
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Affiliation(s)
- Xulun Zhang
- From the Department of Neurobiology, The University of Chicago, Chicago, Illinois 60637 and
| | - Eric Sullivan
- From the Department of Neurobiology, The University of Chicago, Chicago, Illinois 60637 and
| | - Maggie Scimeca
- From the Department of Neurobiology, The University of Chicago, Chicago, Illinois 60637 and
| | - Xianzhong Wu
- the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Yue-Ming Li
- the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Sangram S Sisodia
- From the Department of Neurobiology, The University of Chicago, Chicago, Illinois 60637 and
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105
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Structural biology of intramembrane proteases: mechanistic insights from rhomboid and S2P to γ-secretase. Curr Opin Struct Biol 2016; 37:97-107. [PMID: 26811996 DOI: 10.1016/j.sbi.2015.12.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 12/14/2015] [Accepted: 12/28/2015] [Indexed: 12/21/2022]
Abstract
Intramembrane proteases catalyze hydrolysis of peptide bond within the lipid bilayer and play a key role in a variety of cellular processes. These membrane-embedded enzymes comprise four major classes: rhomboid serine proteases, site-2 metalloproteases, Rce1-type glutamyl proteases, and aspartyl proteases exemplified by signal peptide peptidase and γ-secretase. In the past several years, three-dimensional structures of representative members of these four classes of intramembrane protease have been reported at atomic resolutions, which reveal distinct protein folds and active site configurations. These structures, together with structure-guided biochemical analyses, shed light on the working mechanisms of water access and substrate entry. In this review, we discuss the shared as well as unique features of these intramembrane proteases, with a focus on presenilin-the catalytic component of γ-secretase.
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106
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Li Y, Liew LSY, Li Q, Kang C. Structure of the transmembrane domain of human nicastrin-a component of γ-secretase. Sci Rep 2016; 6:19522. [PMID: 26776682 PMCID: PMC4726005 DOI: 10.1038/srep19522] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 12/09/2015] [Indexed: 02/04/2023] Open
Abstract
Nicastrin is the largest component of γ-secretase that is an intramembrane protease important in the development of Alzheimer's disease. Nicastrin contains a large extracellular domain, a single transmembrane (TM) domain, and a short C-terminus. Its TM domain is important for the γ-secretase complex formation. Here we report nuclear magnetic resonance (NMR) studies of the TM and C-terminal regions of human nicastrin in both sodium dodecyl sulfate (SDS) and dodecylphosphocholine (DPC) micelles. Structural study and dynamic analysis reveal that the TM domain is largely helical and stable under both SDS and DPC micelles with its N-terminal region undergoing intermediate time scale motion. The TM helix contains a hydrophilic patch that is important for TM-TM interactions. The short C-terminus is not structured in solution and a region formed by residues V697-A702 interacts with the membrane, suggesting that these residues may play a role in the γ-secretase complex formation. Our study provides structural insight into the function of the nicastrin TM domain and the C-terminus in γ-secretase complex.
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Affiliation(s)
- Yan Li
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR), Singapore, 138669 Singapore
| | - Lynette Sin Yee Liew
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR), Singapore, 138669 Singapore
| | - Qingxin Li
- Institute of Chemical &Engineering Sciences, 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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107
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Hu C, Zeng L, Li T, Meyer MA, Cui MZ, Xu X. Nicastrin is required for amyloid precursor protein (APP) but not Notch processing, while anterior pharynx-defective 1 is dispensable for processing of both APP and Notch. J Neurochem 2016; 136:1246-1258. [PMID: 26717550 DOI: 10.1111/jnc.13518] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/20/2015] [Accepted: 12/22/2015] [Indexed: 11/27/2022]
Abstract
The γ-secretase complex is composed of at least four components: presenilin 1 or presenilin-2, nicastrin (NCT), anterior pharynx-defective 1 (Aph-1), and presenilin enhancer 2. In this study, using knockout cell lines, our data demonstrated that knockout of NCT, as well as knockout of presenilin enhancer 2, completely blocked γ-secretase-catalyzed processing of C-terminal fragment (CTF)α and CTFβ, the C-terminal fragments of β-amyloid precursor protein (APP) produced by α-secretase and β-secretase cleavages, respectively. Interestingly, in Aph-1-knockout cells, CTFα and CTFβ were still processed by γ-secretase, indicating Aph-1 is dispensable for APP processing. Furthermore, our results indicate that Aph-1 as well as NCT is not absolutely required for Notch processing, suggesting that NCT is differentially required for APP and Notch processing. In addition, our data revealed that components of the γ-secretase complex are also important for proteasome- and lysosome-dependent degradation of APP and that endogenous APP is mostly degraded by lysosome while exogenous APP is mainly degraded by proteasome. There are unanswered questions regarding the roles of each component of the γ-secretase complex in amyloid precursor protein (APP) and Notch processing. The most relevant, novel finding of this study is that nicastrin (NCT) is required for APP but not Notch processing, while Aph-1 is not essential for processing of both APP and Notch, suggesting NCT as a therapeutic target to restrict Aβ formation without impairing Notch signaling.
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Affiliation(s)
- Chen Hu
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA
| | - Linlin Zeng
- School of Life Sciences, Jilin University, Changchun, China
| | - Ting Li
- Department of Cell Biology, Tianjin Medical University, Tianjin, China
| | | | - Mei-Zhen Cui
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA
| | - Xuemin Xu
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA
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108
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Xiao X, He Y, Li C, Zhang X, Xu H, Wang B. Nicastrin mutations in familial acne inversa impact keratinocyte proliferation and differentiation through the Notch and phosphoinositide 3-kinase/AKT signalling pathways. Br J Dermatol 2016; 174:522-32. [PMID: 26473517 DOI: 10.1111/bjd.14223] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/05/2015] [Indexed: 12/12/2022]
Abstract
BACKGROUND Acne inversa (AI) is a chronic inflammatory skin disease with an autosomal dominant inheritance pattern. Mutations of the gene encoding nicastrin (NCSTN), a cofactor subunit of γ-secretase, are responsible for familial AI. However, whether deficiency of nicastrin is functionally implicated in the biological behaviours of human keratinocytes and related molecular mechanisms remains unknown. OBJECTIVES To study alterations of biological traits and related signalling pathways modulated by nicastrin knockdown in keratinocytes. METHODS A human immortalized keratinocyte cell line (HaCaT) was treated with efficient small interfering (si)RNA-targeted NCSTN. Cell proliferation was measured by CCK-8 assay; cell-cycle and cell apoptosis analyses were detected by flow cytometry. Microarray analysis was applied to uncover impacts of NCSTN silencing on whole-genome expression of HaCaT cells. Altered signalling pathways were further confirmed by real-time polymerase chain reaction, Western blotting and immunohistochemistry in both HaCaT cells and lesions of a patient with AI with NCSTN mutation. RESULTS NCSTN knockdown in HaCaT cells impaired γ-secretase activity, leading to increased cell proliferation and S-phase population. Microarray data also showed that numerous genes and pathways implicated in proliferation and differentiation of keratinocytes were statistically changed. Among these genes, expression levels of several Notch pathway molecules, known as γ-secretase substrates, were validated to be significantly attenuated in both nicastrin-silencing HaCaT cells and the lesion of the patient. Furthermore, a remarkable elevation of expression of phosphoinositide 3-kinase (PI3K), AKT and its activated form pAKT was illustrated in siRNA-treated HaCaT cells. CONCLUSIONS Deficiency of the NCSTN in familial AI may regulate proliferation and differentiation of keratinocytes mainly through the Notch and PI3K/AKT signalling pathways.
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Affiliation(s)
- X Xiao
- Institute of Dermatology, Chinese Academy of Medical Sciences, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China.,Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China
| | - Y He
- Institute of Dermatology, Chinese Academy of Medical Sciences, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China.,Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China
| | - C Li
- Institute of Dermatology, Chinese Academy of Medical Sciences, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China.,Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China
| | - X Zhang
- Institute of Dermatology, Chinese Academy of Medical Sciences, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China.,Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China
| | - H Xu
- Institute of Dermatology, Chinese Academy of Medical Sciences, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China.,Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China
| | - B Wang
- Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, St 12 Jiangwangmiao, Nanjing, Jiangsu, 210042, China.,Institute of Plastic Surgery, Chinese Academy of Medical Sciences, St 33 Ba-Da-Chu Road, Beijing, 100144, China
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109
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Futai E, Osawa S, Cai T, Fujisawa T, Ishiura S, Tomita T. Suppressor Mutations for Presenilin 1 Familial Alzheimer Disease Mutants Modulate γ-Secretase Activities. J Biol Chem 2016; 291:435-46. [PMID: 26559975 PMCID: PMC4697183 DOI: 10.1074/jbc.m114.629287] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 11/07/2015] [Indexed: 12/27/2022] Open
Abstract
γ-Secretase is a multisubunit membrane protein complex containing presenilin (PS1) as a catalytic subunit. Familial Alzheimer disease (FAD) mutations within PS1 were analyzed in yeast cells artificially expressing membrane-bound substrate, amyloid precursor protein, or Notch fused to Gal4 transcriptional activator. The FAD mutations, L166P and G384A (Leu-166 to Pro and Gly-384 to Ala substitution, respectively), were loss-of-function in yeast. We identified five amino acid substitutions that suppress the FAD mutations. The cleavage of amyloid precursor protein or Notch was recovered by the secondary mutations. We also found that secondary mutations alone activated the γ-secretase activity. FAD mutants with suppressor mutations, L432M or S438P within TMD9 together with a missense mutation in the second or sixth loops, regained γ-secretase activity when introduced into presenilin null mouse fibroblasts. Notably, the cells with suppressor mutants produced a decreased amount of Aβ42, which is responsible for Alzheimer disease. These results indicate that the yeast system is useful to screen for mutations and chemicals that modulate γ-secretase activity.
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Affiliation(s)
- Eugene Futai
- From the Department of Molecular and Cell Biology, Graduate School of Agricultural Sciences, Tohoku University, Sendai, Miyagi 981-8555, the Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902,
| | - Satoko Osawa
- the Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences and
| | - Tetsuo Cai
- the Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences and Laboratory of Neuropathology and Neuroscience, Faculty of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tomoya Fujisawa
- From the Department of Molecular and Cell Biology, Graduate School of Agricultural Sciences, Tohoku University, Sendai, Miyagi 981-8555
| | - Shoichi Ishiura
- the Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902
| | - Taisuke Tomita
- the Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences and Laboratory of Neuropathology and Neuroscience, Faculty of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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110
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Hydrogen Sulfide Selectively Inhibits γ-Secretase Activity and Decreases Mitochondrial Aβ Production in Neurons from APP/PS1 Transgenic Mice. Neurochem Res 2015; 41:1145-59. [PMID: 26708452 DOI: 10.1007/s11064-015-1807-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 12/11/2015] [Accepted: 12/12/2015] [Indexed: 10/22/2022]
Abstract
Hydrogen sulfide (H2S) is now considered to be a gasotransmitter and may be involved in the pathological process of Alzheimer's disease (AD). A majority of APP is associated with mitochondria and is a substrate for the mitochondrial γ-secretase. The mitochondria-associated APP metabolism where APP intracellular domains (AICD) and Aβ are generated locally and may contribute to mitochondrial dysfunction in AD. Here, we aimed to investigate the ability of H2S to mediate APP processing in mitochondria and assessed the possible mechanisms underlying H2S-mediated AD development. We treated neurons from APP/PS1 transgenic mice with a range of sodium hydrosulfide (NaHS) concentrations. NaHS attenuated APP processing and decreased Aβ production in mitochondria. Meanwhile, NaHS did not changed BACE-1 and ADAM10 (a disintegrin and metalloprotease 10) protein levels, but NaHS (30 μM) significantly increased the levels of presenilin 1(PS1), PEN-2, and NCT, as well as improved the γ-secretase activity, while NaHS (50 μM) exhibits the opposing effects. Furthermore, the intracellular ATP and the COX IV activity of APP/PS1 neurons were increased after 30 μM NaHS treatment, while the ROS level was decreased and the MMP was stabilized. The effect of NaHS differs from DAPT (a non-selective γ-secretase inhibitor), and it selectively inhibited γ-secretase in vitro, without interacting with Notch and modulating its cleavage. The results indicated that NaHS decreases Aβ accumulation in mitochondria by selectively inhibiting γ-secretase. Thus, we provide a mechanistic view of NaHS is a potential anti-AD drug candidate and it may decrease Aβ deposition in mitochondria by selectively inhibiting γ-secretase activity and therefore protecting the mitochondrial function during AD conditions.
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111
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Nicastrin functions to sterically hinder γ-secretase-substrate interactions driven by substrate transmembrane domain. Proc Natl Acad Sci U S A 2015; 113:E509-18. [PMID: 26699478 DOI: 10.1073/pnas.1512952113] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
γ-Secretase is an intramembrane-cleaving protease that processes many type-I integral membrane proteins within the lipid bilayer, an event preceded by shedding of most of the substrate's ectodomain by α- or β-secretases. The mechanism by which γ-secretase selectively recognizes and recruits ectodomain-shed substrates for catalysis remains unclear. In contrast to previous reports that substrate is actively recruited for catalysis when its remaining short ectodomain interacts with the nicastrin component of γ-secretase, we find that substrate ectodomain is entirely dispensable for cleavage. Instead, γ-secretase-substrate binding is driven by an apparent tight-binding interaction derived from substrate transmembrane domain, a mechanism in stark contrast to rhomboid--another family of intramembrane-cleaving proteases. Disruption of the nicastrin fold allows for more efficient cleavage of substrates retaining longer ectodomains, indicating that nicastrin actively excludes larger substrates through steric hindrance, thus serving as a molecular gatekeeper for substrate binding and catalysis.
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112
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Sparling DP, Yu J, Kim K, Zhu C, Brachs S, Birkenfeld AL, Pajvani UB. Adipocyte-specific blockade of gamma-secretase, but not inhibition of Notch activity, reduces adipose insulin sensitivity. Mol Metab 2015; 5:113-121. [PMID: 26909319 PMCID: PMC4735659 DOI: 10.1016/j.molmet.2015.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 11/18/2015] [Accepted: 11/25/2015] [Indexed: 01/12/2023] Open
Abstract
Objective As the obesity pandemic continues to expand, novel molecular targets to reduce obesity-related insulin resistance and Type 2 Diabetes (T2D) continue to be needed. We have recently shown that obesity is associated with reactivated liver Notch signaling, which, in turn, increases hepatic insulin resistance, opening up therapeutic avenues for Notch inhibitors to be repurposed for T2D. Herein, we tested the systemic effects of γ-secretase inhibitors (GSIs), which prevent endogenous Notch activation, and confirmed these effects through creation and characterization of two different adipocyte-specific Notch loss-of-function mouse models through genetic ablation of the Notch transcriptional effector Rbp-Jk (A-Rbpj) and the obligate γ-secretase component Nicastrin (A-Nicastrin). Methods Glucose homeostasis and both local adipose and systemic insulin sensitivity were examined in GSI-treated, A-Rbpj and A-Nicastrin mice, as well as vehicle-treated or control littermates, with complementary in vitro studies in primary hepatocytes and 3T3-L1 adipocytes. Results GSI-treatment increases hepatic insulin sensitivity in obese mice but leads to reciprocal lowering of adipose glucose disposal. While A-Rbpj mice show normal body weight, adipose development and mass and unchanged adipose insulin sensitivity as control littermates, A-Nicastrin mice are relatively insulin-resistant, mirroring the GSI effect on adipose insulin action. Conclusions Notch signaling is dispensable for normal adipocyte function, but adipocyte-specific γ-secretase blockade reduces adipose insulin sensitivity, suggesting that specific Notch inhibitors would be preferable to GSIs for application in T2D. γ-secretase inhibitors (GSIs) are non-specific inhibitors of Notch signaling. GSI-treatment of obese mice increases hepatic, but lowers adipose insulin sensitivity. Adipocyte-specific Notch inhibition does not affect adipose mass or glucose homeostasis. Adipocyte-specific γ-secretase blockade reduces adipose insulin sensitivity. Specific Notch inhibitors may be preferable to GSIs for treatment of Type 2 Diabetes.
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Affiliation(s)
- David P Sparling
- Departments of Pediatrics, Columbia University, New York, NY 10032, USA
| | - Junjie Yu
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - KyeongJin Kim
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Changyu Zhu
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Sebastian Brachs
- Department of Endocrinology, Diabetes and Nutrition, Center for Cardiovascular Research, Charité - University School of Medicine, Berlin, Germany
| | - Andreas L Birkenfeld
- Section of Metabolic Vascular Medicine, Medical Clinic III and Paul Langerhans Institute Dresden (PLID), a member of the German Center for Diabetes Research (DZD), Technische Universität Dresden, Germany; Section of Diabetes and Nutritional Sciences, Rayne Institute, Denmark Hill Campus, King's College London, UK
| | - Utpal B Pajvani
- Department of Medicine, Columbia University, New York, NY 10032, USA.
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113
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Bai XC, Rajendra E, Yang G, Shi Y, Scheres SHW. Sampling the conformational space of the catalytic subunit of human γ-secretase. eLife 2015; 4. [PMID: 26623517 PMCID: PMC4718806 DOI: 10.7554/elife.11182] [Citation(s) in RCA: 456] [Impact Index Per Article: 50.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 11/30/2015] [Indexed: 12/12/2022] Open
Abstract
Human γ-secretase is an intra-membrane protease that cleaves many different substrates. Aberrant cleavage of Notch is implicated in cancer, while abnormalities in cutting amyloid precursor protein lead to Alzheimer's disease. Our previous cryo-EM structure of γ-secretase revealed considerable disorder in its catalytic subunit presenilin. Here, we describe an image classification procedure that characterizes molecular plasticity at the secondary structure level, and apply this method to identify three distinct conformations in our previous sample. In one of these conformations, an additional transmembrane helix is visible that cannot be attributed to the known components of γ-secretase. In addition, we present a γ-secretase structure in complex with the dipeptidic inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT). Our results reveal how conformational mobility in the second and sixth transmembrane helices of presenilin is greatly reduced upon binding of DAPT or the additional helix, and form the basis for a new model of how substrate enters the transmembrane domain. DOI:http://dx.doi.org/10.7554/eLife.11182.001 An enzyme called gamma-secretase cuts other proteins in cells into smaller pieces. Like most enzymes, gamma-secretase is expected to move through several different three-dimensional shapes to perform its role, and identifying these structures could help us to understand how the enzyme works. One of the proteins that is targeted by gamma-secretase is called amyloid precursor protein, and cutting this protein results in the formation of so-called amyloid-beta peptides. When gamma-secretase doesn't work properly, these amyloid-beta peptides can accumulate in the brain and large accumulations of these peptides have been observed in the brains of patients with Alzheimer's disease. Earlier in 2015, a group of researchers used a technique called cryo-electron microscopy (cryo-EM) to produce a three-dimensional model of gamma-secretase. This revealed that the active site of the enzyme, that is, the region that is used to cut the other proteins, is particularly flexible. Now, Bai et al. – including many of the researchers from the earlier work – studied this flexibility in more detail. For the experiments, gamma-secretase was exposed to an inhibitor molecule that stopped it from cutting other proteins. This meant that the structure of gamma-secretase became more rigid than normal, which made it possible to collect more detailed structural information using cryo-EM. Bai et al. also developed new methods for processing images to separate the images of individual enzyme molecules based on the different shapes they had adopted at the time. These methods make it possible to view a mixture of very similar enzyme structures that differ only in a small region of the protein (in this case the active site). In the future, it would be useful to repeat these imaging experiments using a range of different molecules that alter the activity of gamma-secretase. Furthermore, the new image processing methods developed by Bai et al. could be used to study flexibility in the shapes of other proteins. DOI:http://dx.doi.org/10.7554/eLife.11182.002
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Affiliation(s)
- Xiao-chen Bai
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Eeson Rajendra
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Guanghui Yang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yigong Shi
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
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Lei X, Yu J, Niu Q, Liu J, Fraering PC, Wu F. The FDA-approved natural product dihydroergocristine reduces the production of the Alzheimer's disease amyloid-β peptides. Sci Rep 2015; 5:16541. [PMID: 26567970 PMCID: PMC4644980 DOI: 10.1038/srep16541] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 10/15/2015] [Indexed: 02/05/2023] Open
Abstract
Known γ-secretase inhibitors or modulators display an undesirable pharmacokinetic profile and toxicity and have therefore not been successful in clinical trials for Alzheimer's disease (AD). So far, no compounds from natural products have been identified as direct inhibitors of γ-secretase. To search for bioactive molecules that can reduce the amount of amyloid-beta peptides (Aβ) and that have better pharmacokinetics and an improved safety profile, we completed a screen of ~400 natural products by using cell-based and cell-free γ-secretase activity assays. We identified dihydroergocristine (DHEC), a component of an FDA- (Food and Drug Administration)-approved drug, to be a direct inhibitor of γ-secretase. Micromolar concentrations of DHEC substantially reduced Aβ levels in different cell types, including a cell line derived from an AD patient. Structure-activity relationship studies implied that the key moiety for inhibiting γ-secretase is the cyclized tripeptide moiety of DHEC. A Surface Plasmon Resonance assay showed that DHEC binds directly to γ-secretase and Nicastrin, with equilibrium dissociation constants (Kd) of 25.7 nM and 9.8 μM, respectively. This study offers DHEC not only as a new chemical moiety for selectively modulating the activity of γ-secretase but also a candidate for drug repositioning in Alzheimer's disease.
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Affiliation(s)
- Xiling Lei
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jing Yu
- State Key Laboratory of Microbial Metabolism & School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Qi Niu
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jianhua Liu
- State Key Laboratory of Microbial Metabolism & School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Patrick C. Fraering
- Brain Mind Institute, School of Life Sciences, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | - Fang Wu
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
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Kokawa A, Ishihara S, Fujiwara H, Nobuhara M, Iwata M, Ihara Y, Funamoto S. The A673T mutation in the amyloid precursor protein reduces the production of β-amyloid protein from its β-carboxyl terminal fragment in cells. Acta Neuropathol Commun 2015; 3:66. [PMID: 26531305 PMCID: PMC4632685 DOI: 10.1186/s40478-015-0247-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 10/22/2015] [Indexed: 12/16/2022] Open
Abstract
Introduction The A673T mutation in the amyloid precursor protein (APP) protects against Alzheimer’s disease by reducing β-amyloid protein (Aβ) production. This mutation reduced the release of the soluble APP fragment (sAPPβ), which is processed by β-secretase, suggesting a concomitant decrease in the β-carboxyl fragment of APP (C99), which is a direct substrate of γ-secretase for Aβ production. However, it remains controversial whether the level of C99 is significantly reduced in cells expressing APP that carry A673T as the cause of reduced Aβ production. Here, we investigated the effect of the A673T mutation in C99 on γ-cleavage in cells. Results We found that the level of C99 in cells expressing APP A673T was indistinctive of that observed in cells expressing wild-type APP, although the release of sAPPβ was significantly reduced in the APP A673T cells. In addition, our reconstituted β-secretase assay demonstrated no significant difference in β-cleavage on an APP fragment carrying the A673T mutation compared with the wild-type fragment. Importantly, cells expressing C99 containing the A673T mutation (C99 A2T; in accordance with the Aβ numbering) produced roughly half the level of Aβ compared with the wild-type C99, suggesting that the C99 A2T is an insufficient substrate of γ-secretase in cells. A cell-free γ-secretase assay revealed that Aβ production from the microsomal fraction of cells expressing C99 A2T was diminished. A sucrose gradient centrifugation analysis indicated that the levels of the C99 A2T that was codistributed with γ-secretase components in the raft fractions were reduced significantly. Conclusions Our data indicate that the A673T mutation in APP alters the release of sAPPβ, but not the C99 level, and that the C99 A2T is an inefficient substrate for γ-secretase in cell-based assay. Electronic supplementary material The online version of this article (doi:10.1186/s40478-015-0247-6) contains supplementary material, which is available to authorized users.
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Abstract
Dysfunction of the intramembrane protease γ-secretase is thought to cause Alzheimer's disease, with most mutations derived from Alzheimer's disease mapping to the catalytic subunit presenilin 1 (PS1). Here we report an atomic structure of human γ-secretase at 3.4 Å resolution, determined by single-particle cryo-electron microscopy. Mutations derived from Alzheimer's disease affect residues at two hotspots in PS1, each located at the centre of a distinct four transmembrane segment (TM) bundle. TM2 and, to a lesser extent, TM6 exhibit considerable flexibility, yielding a plastic active site and adaptable surrounding elements. The active site of PS1 is accessible from the convex side of the TM horseshoe, suggesting considerable conformational changes in nicastrin extracellular domain after substrate recruitment. Component protein APH-1 serves as a scaffold, anchoring the lone transmembrane helix from nicastrin and supporting the flexible conformation of PS1. Ordered phospholipids stabilize the complex inside the membrane. Our structure serves as a molecular basis for mechanistic understanding of γ-secretase function.
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Wang X, Cui J, Li W, Zeng X, Zhao J, Pei G. γ-Secretase Modulators and Inhibitors Induce Different Conformational Changes of Presenilin 1 Revealed by FLIM and FRET. J Alzheimers Dis 2015; 47:927-37. [DOI: 10.3233/jad-150313] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Xin Wang
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Jin Cui
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Wei Li
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xianglu Zeng
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Shanghai Key Laboratory of Signaling and Disease Research, Laboratory of Receptor-based Bio-medicine, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jian Zhao
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Gang Pei
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, and the Collaborative Innovation Center for Brain Science, Tongji University, Shanghai, China
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118
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Jo EH, Ahn JS, Mo JS, Yoon JH, Ann EJ, Baek HJ, Lee HJ, Kim SH, Kim MY, Park HS. Akt1 phosphorylates Nicastrin to regulate its protein stability and activity. J Neurochem 2015; 134:799-810. [DOI: 10.1111/jnc.13173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 04/02/2015] [Accepted: 05/05/2015] [Indexed: 11/28/2022]
Affiliation(s)
- Eun-Hye Jo
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Ji-Seon Ahn
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Jung-Soon Mo
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Ji-Hye Yoon
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Eun-Jung Ann
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Hyeong-Jin Baek
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Hye-Jin Lee
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Seol-Hee Kim
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Mi-Yeon Kim
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Hee-Sae Park
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
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119
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López AR, Dimitrov M, Gerber H, Braman V, Hacker DL, Wurm FM, Fraering PC. Production of active glycosylation-deficient γ-secretase complex for crystallization studies. Biotechnol Bioeng 2015; 112:2516-26. [PMID: 26059427 DOI: 10.1002/bit.25675] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/28/2015] [Accepted: 06/01/2015] [Indexed: 12/26/2022]
Abstract
Alzheimer's disease (AD)-associated γ-secretase is a ubiquitously expressed multi-subunit protease complex embedded in the lipid bilayer of cellular compartments including endosomes and the plasma membrane. Although γ-secretase is of crucial interest for AD drug discovery, its atomic structure remains unresolved. γ-Secretase assembly and maturation is a multistep process, which includes extensive glycosylation on nicastrin (NCT), the only γ-secretase subunit having a large extracellular domain. These posttranslational modifications lead to protein heterogeneity that likely prevents the three-dimensional (3D) crystallization of the protease complex. To overcome this issue, we have engineered a Chinese hamster ovary (CHO) cell line deficient in complex sugar modifications (CHO lec1) to overexpress the four subunits of γ-secretase as a functional complex. We purified glycosylation-deficient γ-secretase from this recombinant cell line (CL1-9) and fully glycosylated γ-secretase from a recombinant CHO DG44-derived cell line (SS20). We characterized both complexes biochemically and pharmacologically in vitro. Interestingly, we found that the complex oligosaccharides, which largely decorate the extracellular domain of fully glycosylated NCT, are not involved in the proper assembly and maturation of the complex, and are dispensable for the specific generation, in physiological ratios, of the amyloid precursor protein (APP) cleavage products. In conclusion, we propose a novel bioengineering approach for the production of functional glycosylation-deficient γ-secretase, which may be suitable for crystallization studies. We expect that these findings will contribute both to solving the high-resolution 3D structure of γ-secretase and to structure-based drug discovery for AD.
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Affiliation(s)
- Andrés Ricardo López
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Mitko Dimitrov
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Hermeto Gerber
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Virginie Braman
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - David L Hacker
- Laboratory for Cellular Biotechnology, Institute of Bioengineering and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Florian M Wurm
- Laboratory for Cellular Biotechnology, Institute of Bioengineering and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Patrick C Fraering
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland.
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120
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Chen MK, Hung MC. Proteolytic cleavage, trafficking, and functions of nuclear receptor tyrosine kinases. FEBS J 2015; 282:3693-721. [PMID: 26096795 DOI: 10.1111/febs.13342] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 05/18/2015] [Accepted: 06/09/2015] [Indexed: 01/18/2023]
Abstract
Intracellular localization has been reported for over three-quarters of receptor tyrosine kinase (RTK) families in response to environmental stimuli. Internalized RTK may bind to non-canonical substrates and affect various cellular processes. Many of the intracellular RTKs exist as fragmented forms that are generated by γ-secretase cleavage of the full-length receptor, shedding, alternative splicing, or alternative translation initiation. Soluble RTK fragments are stabilized and intracellularly transported into subcellular compartments, such as the nucleus, by binding to chaperone or transcription factors, while membrane-bound RTKs (full-length or truncated) are transported from the plasma membrane to the ER through the well-established Rab- or clathrin adaptor protein-coated vesicle retrograde trafficking pathways. Subsequent nuclear transport of membrane-bound RTK may occur via two pathways, INFS or INTERNET, with the former characterized by release of receptors from the ER into the cytosol and the latter characterized by release of membrane-bound receptor from the ER into the nucleoplasm through the inner nuclear membrane. Although most non-canonical intracellular RTK signaling is related to transcriptional regulation, there may be other functions that have yet to be discovered. In this review, we summarize the proteolytic processing, intracellular trafficking and nuclear functions of RTKs, and discuss how they promote cancer progression, and their clinical implications.
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Affiliation(s)
- Mei-Kuang Chen
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX, USA.,Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mien-Chie Hung
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX, USA.,Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Center of Molecular Medicine and Graduate Institute of Cancer Biology, China Medical University, Taichung, Taiwan.,Department of Biotechnology, Asia University, Taichung, Taiwan
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121
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Lim A, Moussavi Nik SH, Ebrahimie E, Lardelli M. Analysis of nicastrin gene phylogeny and expression in zebrafish. Dev Genes Evol 2015; 225:171-8. [DOI: 10.1007/s00427-015-0500-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 04/24/2015] [Indexed: 11/24/2022]
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122
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Abstract
The four-component intramembrane protease γ-secretase is intricately linked to the development of Alzheimer's disease. Despite recent structural advances, the transmembrane segments (TMs) of γ-secretase remain to be specifically assigned. Here we report a 3D structure of human γ-secretase at 4.32-Å resolution, determined by single-particle, electron cryomicroscopy in the presence of digitonin and with a T4 lysozyme fused to the amino terminus of presenilin 1 (PS1). The overall structure of this human γ-secretase is very similar to that of wild-type γ-secretase determined in the presence of amphipols. The 20 TMs are unambiguously assigned to the four components, revealing principles of subunit assembly. Within the transmembrane region, PS1 is centrally located, with its amino-terminal fragment (NTF) packing against Pen-2 and its carboxyl-terminal fragment (CTF) interacting with Aph-1. The only TM of nicastrin associates with Aph-1 at the thick end of the TM horseshoe, and the extracellular domain of nicastrin directly binds Pen-2 at the thin end. TM6 and TM7 in PS1, which harbor the catalytic aspartate residues, are located on the convex side of the TM horseshoe. This structure serves as an important framework for understanding the function and mechanism of γ-secretase.
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123
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Chu Y, Peng X, Long Z, Wang K, Luo S, Sharma A, He G. Distribution and expression of Pen-2 in the central nervous system of APP/PS1 double transgenic mice. Acta Biochim Biophys Sin (Shanghai) 2015; 47:258-66. [PMID: 25736404 DOI: 10.1093/abbs/gmv010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The γ-secretase complex catalyzes the final cleavage step of amyloid β-protein precursor (APP) to generate amyloid β (Aβ) peptide, a pathogenic component of senile plaques in the brain of Alzheimer's disease (AD) patients. Recent studies have shown that presenilin enhancer-2 (Pen-2), presenilin (PS, including PS1 and PS2), nicastrin, and anterior pharynx-defective 1 are essential components of the γ-secretase. The structure and function of Pen-2 in vitro have been well defined. However, little is known about the neuroanatomical distribution and expression of Pen-2 in the central nervous system (CNS) of AD model mice. We report here, using various methods such as immunohistochemical staining and immunoblotting, that Pen-2 is widely expressed at specific neuronal cells of major areas in AD model mice, including the olfactory bulb, basal forebrain, striatum, cortex, hippocampus, amygdala, thalamus, hypothalamus, cerebellum, brainstem, and spinal cord. It is co-expressed with PS1 in specific neuronal cells in mouse brain. Pen-2 is distributed much more extensively than extracellular amyloid deposits, suggesting the importance of other factors in localized amyloid deposition. Pen-2 is localized predominantly in cell membrane and cytoplasma in adult AD mice, but only distributed at cell membrane in controls. At the early stages of postnatal development, the expression level of Pen-2 is relatively high in CNS, but declines, gradually in adult mice. The present study provides an anatomical basis for Pen-2 as a key component of γ-secretase complex in the brain of developing and adult mice, and Pen-2 might be closely related to Aβ burden in aging nervous system.
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Affiliation(s)
- Yanan Chu
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China
| | - Xuehua Peng
- Department of Radiology, Pediatric Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Zhiming Long
- Department of Anatomy, Chongqing Medical University, Chongqing 400016, China
| | - Kejian Wang
- Department of Anatomy, Chongqing Medical University, Chongqing 400016, China
| | - Shifang Luo
- Department of Anatomy, Chongqing Medical University, Chongqing 400016, China
| | - Akhilesh Sharma
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China
| | - Guiqiong He
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China Department of Anatomy, Chongqing Medical University, Chongqing 400016, China
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Cleavage of amyloid precursor protein by an archaeal presenilin homologue PSH. Proc Natl Acad Sci U S A 2015; 112:3344-9. [PMID: 25733893 DOI: 10.1073/pnas.1502150112] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Aberrant cleavage of amyloid precursor protein (APP) by γ-secretase contributes to the development of Alzheimer's disease. More than 200 disease-derived mutations have been identified in presenilin (the catalytic subunit of γ-secretase), making modulation of γ-secretase activity a potentially attractive therapeutic opportunity. Unfortunately, the technical challenges in dealing with intact γ-secretase have hindered discovery of modulators and demand a convenient substitute approach. Here we report that, similar to γ-secretase, the archaeal presenilin homolog PSH faithfully processes the substrate APP C99 into Aβ42, Aβ40, and Aβ38. The molar ratio of the cleavage products Aβ42 over Aβ40 by PSH is nearly identical to that by γ-secretase. The proteolytic activity of PSH is specifically suppressed by presenilin-specific inhibitors. Known modulators of γ-secretase also modulate PSH similarly in terms of the Aβ42/Aβ40 ratio. Structural analysis reveals association of a known γ-secretase inhibitor with PSH between its two catalytic aspartate residues. These findings identify PSH as a surrogate protease for the screening of agents that may regulate the protease activity and the cleavage preference of γ-secretase.
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125
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Mao L. NOTCH mutations: multiple faces in human malignancies. Cancer Prev Res (Phila) 2015; 8:259-61. [PMID: 25712049 DOI: 10.1158/1940-6207.capr-15-0063] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 02/16/2015] [Indexed: 11/16/2022]
Abstract
NOTCH proteins have been implicated in multiple cellular functions, such as stem cell maintenance and cell fate determination. Initially identified as proto-oncogenes because they promote the development of certain types of leukemia, inactivating mutations of NOTCH were later reported. Together with the potential distinct functions of NOTCH family members, their ligands and associated niches, the precise roles of NOTCH in human cancers, particularly solid tumors, remain unsettled. In oral squamous cell carcinoma (OSCC), mutations of NOTCH1 are found in 10% to 15% tumors from Caucasian patients, mostly inactivating mutations. Recent studies of OSCC from Chinese patients, however, showed mutation rates of NOTCH1 about 50% with a considerable portion of potential activating mutations. These findings add another twist into the already complex picture of NOTCH alterations in human cancers, calling for further investigation to uncover what role exactly these molecules play in cancer initiation and progression to develop strategies targeting NOTCH signaling for cancer prevention and treatment.
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Affiliation(s)
- Li Mao
- Department of Oncology and Diagnostic Sciences, University of Maryland School of Dentistry, Baltimore, Maryland.
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126
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Gertsik N, Chiu D, Li YM. Complex regulation of γ-secretase: from obligatory to modulatory subunits. Front Aging Neurosci 2015; 6:342. [PMID: 25610395 PMCID: PMC4285130 DOI: 10.3389/fnagi.2014.00342] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 12/09/2014] [Indexed: 11/29/2022] Open
Abstract
γ-Secretase is a four subunit, 19-pass transmembrane enzyme that cleaves amyloid precursor protein (APP), catalyzing the formation of amyloid beta (Aβ) peptides that form amyloid plaques, which contribute to Alzheimer’s disease (AD) pathogenesis. γ-Secretase also cleaves Notch, among many other type I transmembrane substrates. Despite its seemingly promiscuous enzymatic capacity, γ-secretase activity is tightly regulated. This regulation is a function of many cellular entities, including but not limited to the essential γ-secretase subunits, nonessential (modulatory) subunits, and γ-secretase substrates. Regulation is also accomplished by an array of cellular events, such as presenilin (active subunit of γ-secretase) endoproteolysis and hypoxia. In this review we discuss how γ-secretase is regulated with the hope that an advanced understanding of these mechanisms will aid in the development of effective therapeutics for γ-secretase-associated diseases like AD and Notch-addicted cancer.
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Affiliation(s)
- Natalya Gertsik
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center New York, NY, USA ; Biochemistry and Molecular Biology Program, Weill Graduate School of Medical Sciences of Cornell University New York, NY, USA
| | - Danica Chiu
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center New York, NY, USA ; Program of Pharmacology, Weill Graduate School of Medical Sciences of Cornell University New York, NY, USA
| | - Yue-Ming Li
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center New York, NY, USA ; Program of Pharmacology, Weill Graduate School of Medical Sciences of Cornell University New York, NY, USA
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127
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Li Y, Bohm C, Dodd R, Chen F, Qamar S, Schmitt-Ulms G, Fraser PE, St George-Hyslop PH. Structural biology of presenilin 1 complexes. Mol Neurodegener 2014; 9:59. [PMID: 25523933 PMCID: PMC4326451 DOI: 10.1186/1750-1326-9-59] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 12/12/2014] [Indexed: 11/17/2022] Open
Abstract
The presenilin genes were first identified as the site of missense mutations causing early onset autosomal dominant familial Alzheimer's disease. Subsequent work has shown that the presenilin proteins are the catalytic subunits of a hetero-tetrameric complex containing APH1, nicastrin and PEN-2. This complex (variously termed presenilin complex or gamma-secretase complex) performs an unusual type of proteolysis in which the transmembrane domains of Type I proteins are cleaved within the hydrophobic compartment of the membrane. This review describes some of the molecular and structural biology of this unusual enzyme complex. The presenilin complex is a bilobed structure. The head domain contains the ectodomain of nicastrin. The base domain contains a central cavity with a lateral cleft that likely provides the route for access of the substrate to the catalytic cavity within the centre of the base domain. There are reciprocal allosteric interactions between various sites in the complex that affect its function. For instance, binding of Compound E, a peptidomimetic inhibitor to the PS1 N-terminus, induces significant conformational changes that reduces substrate binding at the initial substrate docking site, and thus inhibits substrate cleavage. However, there is a reciprocal allosteric interaction between these sites such that prior binding of the substrate to the initial docking site paradoxically increases the binding of the Compound E peptidomimetic inhibitor. Such reciprocal interactions are likely to form the basis of a gating mechanism that underlies access of substrate to the catalytic site. An increasingly detailed understanding of the structural biology of the presenilin complex is an essential step towards rational design of substrate- and/or cleavage site-specific modulators of presenilin complex function.
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Affiliation(s)
| | | | | | | | | | | | | | - Peter H St George-Hyslop
- Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrookes Hospital, Hills Road, Cambridge CB2 0XY, UK.
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128
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Zhang X, Li Y, Xu H, Zhang YW. The γ-secretase complex: from structure to function. Front Cell Neurosci 2014; 8:427. [PMID: 25565961 PMCID: PMC4263104 DOI: 10.3389/fncel.2014.00427] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 11/27/2014] [Indexed: 12/21/2022] Open
Abstract
One of the most critical pathological features of Alzheimer’s disease (AD) is the accumulation of β-amyloid (Aβ) peptides that form extracellular senile plaques in the brain. Aβ is derived from β-amyloid precursor protein (APP) through sequential cleavage by β- and γ-secretases. γ-secretase is a high molecular weight complex minimally composed of four components: presenilins (PS), nicastrin, anterior pharynx defective 1 (APH-1), and presenilin enhancer 2 (PEN-2). In addition to APP, γ-secretase also cleaves many other type I transmembrane (TM) protein substrates. As a crucial enzyme for Aβ production, γ-secretase is an appealing therapeutic target for AD. Here, we summarize current knowledge on the structure and function of γ-secretase, as well as recent progress in developing γ-secretase targeting drugs for AD treatment.
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Affiliation(s)
- Xian Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University Xiamen, FJ, China
| | - Yanfang Li
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University Xiamen, FJ, China
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University Xiamen, FJ, China ; Degenerative Disease Research Program, Sanford-Burnham Medical Research Institute La Jolla, CA, USA
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University Xiamen, FJ, China
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129
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Morishima-Kawashima M. Molecular mechanism of the intramembrane cleavage of the β-carboxyl terminal fragment of amyloid precursor protein by γ-secretase. Front Physiol 2014; 5:463. [PMID: 25505888 PMCID: PMC4245903 DOI: 10.3389/fphys.2014.00463] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Accepted: 11/11/2014] [Indexed: 01/31/2023] Open
Abstract
Amyloid β-protein (Aβ) plays a central role in the pathogenesis of Alzheimer's disease, the most common age-associated neurodegenerative disorder. Aβ is generated through intramembrane proteolysis of the β-carboxyl terminal fragment (βCTF) of β-amyloid precursor protein (APP) by γ-secretase. The initial cleavage by γ-secretase occurs in the membrane/cytoplasm boundary of the βCTF, liberating the APP intracellular domain (AICD). The remaining βCTFs, which are truncated at the C-terminus (longer Aβs), are then cropped sequentially in a stepwise manner, predominantly at three residue intervals, to generate Aβ. There are two major Aβ product lines which generate Aβ40 and Aβ42 with concomitant release of three and two tripeptides, respectively. Additionally, many alternative cleavages occur, releasing peptides with three to six residues. These modulate the Aβ product lines and define the species and quantity of Aβ generated. Here, we review our current understanding of the intramembrane cleavage of the βCTF by γ-secretase, which may contribute to the future goal of developing an efficient therapeutic strategy for Alzheimer's disease.
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Affiliation(s)
- Maho Morishima-Kawashima
- Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University Sapporo, Japan
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130
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Wasser CR, Masiulis I, Durakoglugil MS, Lane-Donovan C, Xian X, Beffert U, Agarwala A, Hammer RE, Herz J. Differential splicing and glycosylation of Apoer2 alters synaptic plasticity and fear learning. Sci Signal 2014; 7:ra113. [PMID: 25429077 DOI: 10.1126/scisignal.2005438] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Apoer2 is an essential receptor in the central nervous system that binds to the apolipoprotein ApoE. Various splice variants of Apoer2 are produced. We showed that Apoer2 lacking exon 16, which encodes the O-linked sugar (OLS) domain, altered the proteolytic processing and abundance of Apoer2 in cells and synapse number and function in mice. In cultured cells expressing this splice variant, extracellular cleavage of OLS-deficient Apoer2 was reduced, consequently preventing γ-secretase-dependent release of the intracellular domain of Apoer2. Mice expressing Apoer2 lacking the OLS domain had increased Apoer2 abundance in the brain, hippocampal spine density, and glutamate receptor abundance, but decreased synaptic efficacy. Mice expressing a form of Apoer2 lacking the OLS domain and containing an alternatively spliced cytoplasmic tail region that promotes glutamate receptor signaling showed enhanced hippocampal long-term potentiation (LTP), a phenomenon associated with learning and memory. However, these mice did not display enhanced spatial learning in the Morris water maze, and cued fear conditioning was reduced. Reducing the expression of the mutant Apoer2 allele so that the abundance of the protein was similar to that of Apoer2 in wild-type mice normalized spine density, hippocampal LTP, and cued fear learning. These findings demonstrated a role for ApoE receptors as regulators of synaptic glutamate receptor activity and established differential receptor glycosylation as a potential regulator of synaptic function and memory.
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Affiliation(s)
- Catherine R Wasser
- Center for Translational Neurodegeneration Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Irene Masiulis
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Murat S Durakoglugil
- Center for Translational Neurodegeneration Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Courtney Lane-Donovan
- Center for Translational Neurodegeneration Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Xunde Xian
- Center for Translational Neurodegeneration Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Uwe Beffert
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Anandita Agarwala
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Robert E Hammer
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joachim Herz
- Center for Translational Neurodegeneration Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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131
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Zhang X, Hoey R, Koide A, Dolios G, Paduch M, Nguyen P, Wu X, Li Y, Wagner SL, Wang R, Koide S, Sisodia SS. A synthetic antibody fragment targeting nicastrin affects assembly and trafficking of γ-secretase. J Biol Chem 2014; 289:34851-61. [PMID: 25352592 DOI: 10.1074/jbc.m114.609636] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The γ-secretase complex, composed of presenilin, nicastrin (NCT), anterior pharynx-defective 1 (APH-1), and presenilin enhancer 2 (PEN-2), is assembled in a highly regulated manner and catalyzes the intramembranous proteolysis of many type I membrane proteins, including Notch and amyloid precursor protein. The Notch family of receptors plays important roles in cell fate specification during development and in adult tissues, and aberrant hyperactive Notch signaling causes some forms of cancer. γ-Secretase-mediated processing of Notch at the cell surface results in the generation of the Notch intracellular domain, which associates with several transcriptional coactivators involved in nuclear signaling events. On the other hand, γ-secretase-mediated processing of amyloid precursor protein leads to the production of amyloid β (Aβ) peptides that play an important role in the pathogenesis of Alzheimer disease. We used a phage display approach to identify synthetic antibodies that specifically target NCT and expressed them in the single-chain variable fragment (scFv) format in mammalian cells. We show that expression of a NCT-specific scFv clone, G9, in HEK293 cells decreased the production of the Notch intracellular domain but not the production of amyloid β peptides that occurs in endosomal and recycling compartments. Biochemical studies revealed that scFvG9 impairs the maturation of NCT by associating with immature forms of NCT and, consequently, prevents its association with the other components of the γ-secretase complex, leading to degradation of these molecules. The reduced cell surface levels of mature γ-secretase complexes, in turn, compromise the intramembranous processing of Notch.
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Affiliation(s)
| | - Robert Hoey
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
| | - Akiko Koide
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
| | - Georgia Dolios
- the Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Marcin Paduch
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
| | - Phuong Nguyen
- the Department of Neurosciences, University of California, San Diego School of Medicine, La Jolla, California 92093, and
| | - Xianzhong Wu
- Molecular Pharmacology and Chemistry, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Yueming Li
- Molecular Pharmacology and Chemistry, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Steven L Wagner
- the Department of Neurosciences, University of California, San Diego School of Medicine, La Jolla, California 92093, and
| | - Rong Wang
- the Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Shohei Koide
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
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132
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Abstract
The intramembrane protease γ-secretase is a key player in signaling and Alzheimer's disease, but its structural features have remained obscure. A structure reported recently reveals a horseshoe-shaped arrangement of 19 transmembrane helices and an extracellular domain positioned for substrate recognition. This advance bodes well for a finer resolution before long.
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Affiliation(s)
- Michael S Wolfe
- Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | - Dennis J Selkoe
- Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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133
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134
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Chen CY, Malchus NS, Hehn B, Stelzer W, Avci D, Langosch D, Lemberg MK. Signal peptide peptidase functions in ERAD to cleave the unfolded protein response regulator XBP1u. EMBO J 2014; 33:2492-506. [PMID: 25239945 DOI: 10.15252/embj.201488208] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Signal peptide peptidase (SPP) catalyzes intramembrane proteolysis of signal peptides at the endoplasmic reticulum (ER), but has also been suggested to play a role in ER-associated degradation (ERAD). Here, we show that SPP forms a complex with the ERAD factor Derlin1 and the E3 ubiquitin ligase TRC8 to cleave the unfolded protein response (UPR) regulator XBP1u. Cleavage occurs within a so far unrecognized type II transmembrane domain, which renders XBP1u as an SPP substrate through specific sequence features. Additionally, Derlin1 acts in the complex as a substrate receptor by recognizing the luminal tail of XBP1u. Remarkably, this interaction of Derlin1 with XBP1u obviates the need for ectodomain shedding prior to SPP cleavage, commonly required for intramembrane cuts. Furthermore, we show that XBP1u inhibits the UPR transcription factor XBP1s by targeting it toward proteasomal degradation. Thus, we identify an ERAD complex that controls the abundance of XBP1u and thereby tunes signaling through the UPR.
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Affiliation(s)
- Chia-yi Chen
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Nicole S Malchus
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Beate Hehn
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Walter Stelzer
- Lehrstuhl für Chemie der Biopolymere, Department für Biowissenschaftliche Grundlagen, Technische Universität München, Freising, Germany
| | - Dönem Avci
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Dieter Langosch
- Lehrstuhl für Chemie der Biopolymere, Department für Biowissenschaftliche Grundlagen, Technische Universität München, Freising, Germany
| | - Marius K Lemberg
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) DKFZ-ZMBH Allianz, Heidelberg, Germany
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135
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Abstract
γ-Secretase is an intramembrane protease responsible for the generation of amyloid-β (Aβ) peptides. Aberrant accumulation of Aβ leads to the formation of amyloid plaques in the brain of patients with Alzheimer's disease. Nicastrin is the putative substrate-recruiting component of the γ-secretase complex. No atomic-resolution structure had been identified on γ-secretase or any of its four components, hindering mechanistic understanding of γ-secretase function. Here we report the crystal structure of nicastrin from Dictyostelium purpureum at 1.95-Å resolution. The extracellular domain of nicastrin contains a large lobe and a small lobe. The large lobe of nicastrin, thought to be responsible for substrate recognition, associates with the small lobe through a hydrophobic pivot at the center. The putative substrate-binding pocket is shielded from the small lobe by a lid, which blocks substrate entry. These structural features suggest a working model of nicastrin function. Analysis of nicastrin structure provides insights into the assembly and architecture of the γ-secretase complex.
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136
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Abstract
Presenilin is a membrane-embedded intramembrane-cleaving protease with a conserved catalytic G×GD motif. It is the catalytic subunit of γ-secretase, which plays critical roles in developmental biology and the molecular etiology of Alzheimer disease, together with three membrane protein cofactors, nicastrin, Aph-1 and Pen-2. Biochemical and enzymatic analyses have revealed that γ-secretase executes two types of proteolytic activities on a single substrate; an endopeptidase-like cleavage followed by carboxypeptidase-like processive cleavage. Utilizing small molecule inhibitors/modulators together with the substituted cysteine accessibility method, we identified certain residues and regions of presenilin that contribute to the formation of a catalytic pore structure within the lipid bilayer required for its intramembrane-cleaving activity. Recently, determination of the crystal structure of the archaeal presenilin homologue has confirmed the intramembranous location of the two conserved and essential aspartates. In this review, I will introduce the recent progresses in the understanding of the molecular mechanisms of action of this atypical protease.
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Affiliation(s)
- Taisuke Tomita
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
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137
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Han J, Jung S, Jang J, Kam TI, Choi H, Kim BJ, Nah J, Jo DG, Nakagawa T, Nishimura M, Jung YK. OCIAD2 activates γ-secretase to enhance amyloid β production by interacting with nicastrin. Cell Mol Life Sci 2014; 71:2561-76. [PMID: 24270855 PMCID: PMC11113593 DOI: 10.1007/s00018-013-1515-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/31/2013] [Accepted: 11/07/2013] [Indexed: 02/06/2023]
Abstract
The gamma (γ)-secretase holoenzyme is composed of four core proteins and cleaves APP to generate amyloid beta (Aβ), a key molecule that causes major neurotoxicity during the early stage of Alzheimer's disease (AD). However, despite its important role in Aβ production, little is known about the regulation of γ-secretase. OCIAD2, a novel modulator of γ-secretase that stimulates Aβ production, and which was isolated from a genome-wide functional screen using cell-based assays and a cDNA library comprising 6,178 genes. Ectopic expression of OCIAD2 enhanced Aβ production, while reduction of OCIAD2 expression suppressed it. OCIAD2 expression facilitated the formation of an active γ-secretase complex and enhanced subcellular localization of the enzyme components to lipid rafts. OCIAD2 interacted with nicastrin to stimulate γ-secretase activity. OCIAD2 also increased the interaction of nicastrin with C99 and stimulated APP processing via γ-secretase activation, but did not affect Notch processing. In addition, a cell-permeable Tat-OCIAD2 peptide that interfered with the interaction of OCIAD2 with nicastrin interrupted the γ-secretase-mediated AICD production. Finally, OCIAD2 expression was significantly elevated in the brain of AD patients and PDAPP mice. This study identifies OCIAD2 as a selective activator of γ-secretase to increase Aβ generation.
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Affiliation(s)
- Jonghee Han
- Creative Research Initiative (CRI)-Acceleration Research Laboratory, School of Biological Science/Bio-MAX Institute, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-747 Korea
| | - Sunmin Jung
- Creative Research Initiative (CRI)-Acceleration Research Laboratory, School of Biological Science/Bio-MAX Institute, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-747 Korea
| | - Jiyeon Jang
- School of Pharmacy, Sungkyunkwan University, Suwon, Korea
| | - Tae-In Kam
- Creative Research Initiative (CRI)-Acceleration Research Laboratory, School of Biological Science/Bio-MAX Institute, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-747 Korea
| | - Hyunwoo Choi
- Creative Research Initiative (CRI)-Acceleration Research Laboratory, School of Biological Science/Bio-MAX Institute, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-747 Korea
| | - Byung-Ju Kim
- Department of Cell Biology, Albert Einstein College of Medicine, New York City, 10461 NY USA
| | - Jihoon Nah
- Creative Research Initiative (CRI)-Acceleration Research Laboratory, School of Biological Science/Bio-MAX Institute, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-747 Korea
| | - Dong-Gyu Jo
- School of Pharmacy, Sungkyunkwan University, Suwon, Korea
| | - Toshiyuki Nakagawa
- Department of Neurobiology, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Masaki Nishimura
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga Japan
| | - Yong-Keun Jung
- Creative Research Initiative (CRI)-Acceleration Research Laboratory, School of Biological Science/Bio-MAX Institute, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-747 Korea
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138
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Lu P, Bai XC, Ma D, Xie T, Yan C, Sun L, Yang G, Zhao Y, Zhou R, Scheres SHW, Shi Y. Three-dimensional structure of human γ-secretase. Nature 2014; 512:166-170. [PMID: 25043039 DOI: 10.1038/nature13567] [Citation(s) in RCA: 265] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/09/2014] [Indexed: 12/12/2022]
Abstract
The γ-secretase complex, comprising presenilin 1 (PS1), PEN-2, APH-1 and nicastrin, is a membrane-embedded protease that controls a number of important cellular functions through substrate cleavage. Aberrant cleavage of the amyloid precursor protein (APP) results in aggregation of amyloid-β, which accumulates in the brain and consequently causes Alzheimer's disease. Here we report the three-dimensional structure of an intact human γ-secretase complex at 4.5 Å resolution, determined by cryo-electron-microscopy single-particle analysis. The γ-secretase complex comprises a horseshoe-shaped transmembrane domain, which contains 19 transmembrane segments (TMs), and a large extracellular domain (ECD) from nicastrin, which sits immediately above the hollow space formed by the TM horseshoe. Intriguingly, nicastrin ECD is structurally similar to a large family of peptidases exemplified by the glutamate carboxypeptidase PSMA. This structure serves as an important basis for understanding the functional mechanisms of the γ-secretase complex.
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Affiliation(s)
- Peilong Lu
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Xiao-Chen Bai
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Dan Ma
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Tian Xie
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Chuangye Yan
- State Key Laboratory of Bio-membrane and Membrane Biotechnology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Linfeng Sun
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Guanghui Yang
- State Key Laboratory of Bio-membrane and Membrane Biotechnology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Yanyu Zhao
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Rui Zhou
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Sjors H W Scheres
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Yigong Shi
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
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139
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Vahidi A, Glenn G, van der Geer P. Identification and mutagenesis of the TACE and γ-secretase cleavage sites in the colony-stimulating factor 1 receptor. Biochem Biophys Res Commun 2014; 450:782-7. [PMID: 24955855 DOI: 10.1016/j.bbrc.2014.06.061] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 06/12/2014] [Indexed: 01/08/2023]
Abstract
Stimulation of macrophages with phorbolesters, bacterial DNA, or lipopolysaccharides causes regulated intramembrane proteolysis or RIPping of the CSF-1 receptor. This process involves TACE-mediated cleavage in the extracellular domain, followed by γ-secretase-mediated cleavage within the transmembrane region. In the current study, we have identified the TACE cleavage site, which is present twelve residues from the carboxy-terminal end of the extracellular domain. Replacement of fourteen residues at the end of the extracellular domain blocked TACE cleavage. In addition, we identified the γ-secretase cleavage site, which is present four residues from the carboxy-terminal end of the transmembrane region. Replacement of six residues surrounding this site strongly reduced intramembrane cleavage. Our results provide new insights into the molecular physiology of the CSF-1 receptor and contribute to our understanding of substrate selection by TACE and γ-secretase.
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Affiliation(s)
- Arrash Vahidi
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182-1030, USA
| | - Gary Glenn
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182-1030, USA
| | - Peter van der Geer
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182-1030, USA.
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140
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Brady OA, Zhou X, Hu F. Regulated intramembrane proteolysis of the frontotemporal lobar degeneration risk factor, TMEM106B, by signal peptide peptidase-like 2a (SPPL2a). J Biol Chem 2014; 289:19670-80. [PMID: 24872421 DOI: 10.1074/jbc.m113.515700] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The sequential processing of single pass transmembrane proteins via ectodomain shedding followed by intramembrane proteolysis is involved in a wide variety of signaling processes, as well as maintenance of membrane protein homeostasis. Here we report that the recently identified frontotemporal lobar degeneration risk factor TMEM106B undergoes regulated intramembrane proteolysis. We demonstrate that TMEM106B is readily processed to an N-terminal fragment containing the transmembrane and intracellular domains, and this processing is dependent on the activities of lysosomal proteases. The N-terminal fragment is further processed into a small, rapidly degraded intracellular domain. The GxGD aspartyl proteases SPPL2a and, to a lesser extent, SPPL2b are responsible for this intramembrane cleavage event. Additionally, the TMEM106B paralog TMEM106A is also lysosomally localized; however, it is not a specific substrate of SPPL2a or SPPL2b. Our data add to the growing list of proteins that undergo intramembrane proteolysis and may shed light on the regulation of the frontotemporal lobar degeneration risk factor TMEM106B.
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Affiliation(s)
- Owen A Brady
- From the Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853
| | - Xiaolai Zhou
- From the Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853
| | - Fenghua Hu
- From the Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853
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141
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Funamoto S, Sasaki T, Ishihara S, Nobuhara M, Nakano M, Watanabe-Takahashi M, Saito T, Kakuda N, Miyasaka T, Nishikawa K, Saido TC, Ihara Y. Substrate ectodomain is critical for substrate preference and inhibition of γ-secretase. Nat Commun 2014; 4:2529. [PMID: 24108142 PMCID: PMC3826621 DOI: 10.1038/ncomms3529] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 09/02/2013] [Indexed: 01/18/2023] Open
Abstract
Understanding the substrate recognition mechanism of γ-secretase is a key step for establishing substrate-specific inhibition of amyloid β-protein (Aβ) production. However, it is widely believed that γ-secretase is a promiscuous protease and that its substrate-specific inhibition is elusive. Here we show that γ-secretase distinguishes the ectodomain length of substrates and preferentially captures and cleaves substrates containing a short ectodomain. We also show that a subset of peptides containing the CDCYCxxxxCxCxSC motif binds to the amino terminus of C99 and inhibits Aβ production in a substrate-specific manner. Interestingly, these peptides suppress β-secretase-dependent cleavage of APP, but not that of sialyltransferase 1. Most importantly, intraperitoneal administration of peptides into mice results in a significant reduction in cerebral Aβ levels. This report provides direct evidence of the substrate preference of γ-secretase and its mechanism. Our results demonstrate that the ectodomain of C99 is a potent target for substrate-specific anti-Aβ therapeutics to combat Alzheimer’s disease. γ-Secretase inhibitors are studied for their potential to treat Alzheimer’s disease, but their use is limited by side effects. Funamoto et al. show that γ-secretase preferentially cleaves substrates with short ectodomains and that inhibitors based on these ectodomains reduce disease-like pathology in mice.
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Affiliation(s)
- Satoru Funamoto
- 1] Department of Neuropathology, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan [2] Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan
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142
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Ntziachristos P, Lim JS, Sage J, Aifantis I. From fly wings to targeted cancer therapies: a centennial for notch signaling. Cancer Cell 2014; 25:318-34. [PMID: 24651013 PMCID: PMC4040351 DOI: 10.1016/j.ccr.2014.02.018] [Citation(s) in RCA: 284] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Revised: 01/21/2014] [Accepted: 02/21/2014] [Indexed: 12/21/2022]
Abstract
Since Notch phenotypes in Drosophila melanogaster were first identified 100 years ago, Notch signaling has been extensively characterized as a regulator of cell-fate decisions in a variety of organisms and tissues. However, in the past 20 years, accumulating evidence has linked alterations in the Notch pathway to tumorigenesis. In this review, we discuss the protumorigenic and tumor-suppressive functions of Notch signaling, and dissect the molecular mechanisms that underlie these functions in hematopoietic cancers and solid tumors. Finally, we link these mechanisms and observations to possible therapeutic strategies targeting the Notch pathway in human cancers.
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Affiliation(s)
- Panagiotis Ntziachristos
- Howard Hughes Medical Institute and Department of Pathology, NYU School of Medicine, New York, NY 10016, USA; NYU Cancer Institute and Helen L. and Martin S. Kimmel Center for Stem Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Jing Shan Lim
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Julien Sage
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA.
| | - Iannis Aifantis
- Howard Hughes Medical Institute and Department of Pathology, NYU School of Medicine, New York, NY 10016, USA; NYU Cancer Institute and Helen L. and Martin S. Kimmel Center for Stem Cell Biology, NYU School of Medicine, New York, NY 10016, USA.
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143
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Abstract
The Notch signaling pathway is a regulator of self-renewal and differentiation in several tissues and cell types. Notch is a binary cell-fate determinant, and its hyperactivation has been implicated as oncogenic in several cancers including breast cancer and T-cell acute lymphoblastic leukemia (T-ALL). Recently, several studies also unraveled tumor-suppressor roles for Notch signaling in different tissues, including tissues where it was before recognized as an oncogene in specific lineages. Whereas involvement of Notch as an oncogene in several lymphoid malignancies (T-ALL, B-chronic lymphocytic leukemia, splenic marginal zone lymphoma) is well characterized, there is growing evidence involving Notch signaling as a tumor suppressor in myeloid malignancies. It therefore appears that Notch signaling pathway's oncogenic or tumor-suppressor abilities are highly context dependent. In this review, we summarize and discuss latest advances in the understanding of this dual role in hematopoiesis and the possible consequences for the treatment of hematologic malignancies.
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144
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Kamat S, Yeola S, Zhang W, Bianchi L, Driscoll M. NRA-2, a nicalin homolog, regulates neuronal death by controlling surface localization of toxic Caenorhabditis elegans DEG/ENaC channels. J Biol Chem 2014; 289:11916-11926. [PMID: 24567339 DOI: 10.1074/jbc.m113.533695] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hyperactivated DEG/ENaCs induce neuronal death through excessive cation influx and disruption of intracellular calcium homeostasis. Caenorhabditis elegans DEG/ENaC MEC-4 is hyperactivated by the (d) mutation and induces death of touch neurons. The analogous substitution in MEC-10 (MEC-10(d)) co-expressed in the same neurons is only mildly neurotoxic. We exploited the lower toxicity of MEC-10(d) to identify RNAi knockdowns that enhance neuronal death. We report here that knock-out of the C. elegans nicalin homolog NRA-2 enhances MEC-10(d)-induced neuronal death. Cell biological assays in C. elegans neurons show that NRA-2 controls the distribution of MEC-10(d) between the endoplasmic reticulum and the cell surface. Electrophysiological experiments in Xenopus oocytes support this notion and suggest that control of channel distribution by NRA-2 is dependent on the subunit composition. We propose that nicalin/NRA-2 functions in a quality control mechanism to retain mutant channels in the endoplasmic reticulum, influencing the extent of neuronal death. Mammalian nicalin may have a similar role in DEG/ENaC biology, therefore influencing pathological conditions like ischemia.
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Affiliation(s)
- Shaunak Kamat
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Shrutika Yeola
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Wenying Zhang
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Laura Bianchi
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, Florida 33136.
| | - Monica Driscoll
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854.
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145
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Dickey SW, Baker RP, Cho S, Urban S. Proteolysis inside the membrane is a rate-governed reaction not driven by substrate affinity. Cell 2014; 155:1270-81. [PMID: 24315097 DOI: 10.1016/j.cell.2013.10.053] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 08/04/2013] [Accepted: 10/28/2013] [Indexed: 10/25/2022]
Abstract
Enzymatic cleavage of transmembrane anchors to release proteins from the membrane controls diverse signaling pathways and is implicated in more than a dozen diseases. How catalysis works within the viscous, water-excluding, two-dimensional membrane is unknown. We developed an inducible reconstitution system to interrogate rhomboid proteolysis quantitatively within the membrane in real time. Remarkably, rhomboid proteases displayed no physiological affinity for substrates (K(d) ~190 μM/0.1 mol%). Instead, ~10,000-fold differences in proteolytic efficiency with substrate mutants and diverse rhomboid proteases were reflected in k(cat) values alone. Analysis of gate-open mutant and solvent isotope effects revealed that substrate gating, not hydrolysis, is rate limiting. Ultimately, a single proteolytic event within the membrane normally takes minutes. Rhomboid intramembrane proteolysis is thus a slow, kinetically controlled reaction not driven by transmembrane protein-protein affinity. These properties are unlike those of other studied proteases or membrane proteins but are strikingly reminiscent of one subset of DNA-repair enzymes, raising important mechanistic and drug-design implications.
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Affiliation(s)
- Seth W Dickey
- Howard Hughes Medical Institute, Department of Molecular Biology & Genetics, Johns Hopkins University School of Medicine, Room 507 PCTB, 725 North Wolfe Street, Baltimore, MD 21205, USA
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146
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Jiang S, Li Y, Zhang X, Bu G, Xu H, Zhang YW. Trafficking regulation of proteins in Alzheimer's disease. Mol Neurodegener 2014; 9:6. [PMID: 24410826 PMCID: PMC3891995 DOI: 10.1186/1750-1326-9-6] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 12/15/2013] [Indexed: 12/12/2022] Open
Abstract
The β-amyloid (Aβ) peptide has been postulated to be a key determinant in the pathogenesis of Alzheimer’s disease (AD). Aβ is produced through sequential cleavage of the β-amyloid precursor protein (APP) by β- and γ-secretases. APP and relevant secretases are transmembrane proteins and traffic through the secretory pathway in a highly regulated fashion. Perturbation of their intracellular trafficking may affect dynamic interactions among these proteins, thus altering Aβ generation and accelerating disease pathogenesis. Herein, we review recent progress elucidating the regulation of intracellular trafficking of these essential protein components in AD.
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Affiliation(s)
| | | | | | | | | | - Yun-wu Zhang
- Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian 361102, China.
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147
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Tomita T. Secretase inhibitors and modulators for Alzheimer’s disease treatment. Expert Rev Neurother 2014; 9:661-79. [DOI: 10.1586/ern.09.24] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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148
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Voss M, Schröder B, Fluhrer R. Mechanism, specificity, and physiology of signal peptide peptidase (SPP) and SPP-like proteases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2828-39. [PMID: 24099004 DOI: 10.1016/j.bbamem.2013.03.033] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 03/25/2013] [Accepted: 03/29/2013] [Indexed: 01/09/2023]
Abstract
Signal peptide peptidase (SPP) and the homologous SPP-like (SPPL) proteases SPPL2a, SPPL2b, SPPL2c and SPPL3 belong to the family of GxGD intramembrane proteases. SPP/SPPLs selectively cleave transmembrane domains in type II orientation and do not require additional co-factors for proteolytic activity. Orthologues of SPP and SPPLs have been identified in other vertebrates, plants, and eukaryotes. In line with their diverse subcellular localisations ranging from the ER (SPP, SPPL2c), the Golgi (SPPL3), the plasma membrane (SPPL2b) to lysosomes/late endosomes (SPPL2a), the different members of the SPP/SPPL family seem to exhibit distinct functions. Here, we review the substrates of these proteases identified to date as well as the current state of knowledge about the physiological implications of these proteolytic events as deduced from in vivo studies. Furthermore, the present knowledge on the structure of intramembrane proteases of the SPP/SPPL family, their cleavage mechanism and their substrate requirements are summarised. This article is part of a Special Issue entitled: Intramembrane Proteases.
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Affiliation(s)
- Matthias Voss
- Adolf Butenandt Institute for Biochemistry, Ludwig-Maximilians University Munich, Schillerstr. 44, 80336 Munich, Germany
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149
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Wolfe MS. Toward the structure of presenilin/γ-secretase and presenilin homologs. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1828:2886-97. [PMID: 24099007 PMCID: PMC3801419 DOI: 10.1016/j.bbamem.2013.04.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 04/03/2013] [Accepted: 04/11/2013] [Indexed: 01/30/2023]
Abstract
Presenilin is the catalytic component of the γ-secretase complex, a membrane-embedded aspartyl protease that plays a central role in biology and in the pathogenesis of Alzheimer's disease. Upon assembly with its three protein cofactors (nicastrin, Aph-1 and Pen-2), presenilin undergoes autoproteolysis into two subunits, each of which contributes one of the catalytic aspartates to the active site. A family of presenilin homologs, including signal peptide peptidase, possess proteolytic activity without the need for other protein factors, and these simpler intramembrane aspartyl proteases have given insight into the action of presenilin within the γ-secretase complex. Cellular and molecular studies support a nine-transmembrane topology for presenilins and their homologs, and small-molecule inhibitors and cysteine scanning with crosslinking have suggested certain presenilin residues and regions that contribute to substrate recognition and handling. Identification of partial complexes has also offered clues to protein-protein interactions within the γ-secretase complex. Biophysical methods have allowed 3D views of the γ-secretase complex and presenilins. Most recently, the crystal structure of a microbial presenilin homolog has confirmed a nine-transmembrane topology and intramembranous location and proximity of the two conserved and essential aspartates. The crystal structure also provides a platform for the formulation of specific hypotheses regarding substrate interaction and catalysis as well as the pathogenic mechanism of Alzheimer-causing presenilin mutations. This article is part of a Special Issue entitled: Intramembrane Proteases.
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Affiliation(s)
- Michael S Wolfe
- Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, 77 Avenue Louis Pasteur, H.I.M. 754, Boston, MA 02115 USA.
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150
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Sesele K, Thanopoulou K, Paouri E, Tsefou E, Klinakis A, Georgopoulos S. Conditional inactivation of nicastrin restricts amyloid deposition in an Alzheimer's disease mouse model. Aging Cell 2013; 12:1032-40. [PMID: 23826707 DOI: 10.1111/acel.12131] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2013] [Indexed: 12/15/2022] Open
Abstract
Production of Aβ by γ-secretase is a key event in Alzheimer's disease (AD). The γ-secretase complex consists of presenilin (PS) 1 or 2, nicastrin (ncstn), Pen-2, and Aph-1 and cleaves type I transmembrane proteins, including the amyloid precursor protein (APP). Although ncstn is widely accepted as an essential component of the complex required for γ-secretase activity, recent in vitro studies have suggested that ncstn is dispensable for APP processing and Aβ production. The focus of this study was to answer this controversy and evaluate the role of ncstn in Aβ generation and the development of the amyloid-related phenotype in the mouse brain. To eliminate ncstn expression in the mouse brain, we used a ncstn conditional knockout mouse that we mated with an established AD transgenic mouse model (5XFAD) and a neuronal Cre-expressing transgenic mouse (CamKIIα-iCre), to generate AD mice (5XFAD/CamKIIα-iCre/ncstn(f/f) mice) where ncstn was conditionally inactivated in the brain. 5XFAD/CamKIIα-iCre/ncstn(f/f) mice at 10 week of age developed a neurodegenerative phenotype with a significant reduction in Aβ production and formation of Aβ aggregates and the absence of amyloid plaques. Inactivation of nctsn resulted in substantial accumulation of APP-CTFs and altered PS1 expression. These results reveal a key role for ncstn in modulating Aβ production and amyloid plaque formation in vivo and suggest ncstn as a target in AD therapeutics.
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Affiliation(s)
- Katia Sesele
- Department of Cell Biology; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
| | - Kalliopi Thanopoulou
- Department of Cell Biology; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
| | - Evi Paouri
- Department of Cell Biology; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
| | - Eliona Tsefou
- Department of Cell Biology; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
| | - Apostolos Klinakis
- Department of Genetics and Gene Therapy; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
| | - Spiros Georgopoulos
- Department of Cell Biology; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
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