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Makiuchi T, Saito-Nakano Y, Nozaki T. Evidence of γ-secretase complex involved in the regulation of intramembrane proteolysis in Entamoeba histolytica. Parasitol Int 2024; 103:102925. [PMID: 39048023 DOI: 10.1016/j.parint.2024.102925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2024] [Accepted: 07/14/2024] [Indexed: 07/27/2024]
Abstract
Presenilins (PSNs) are multifunctional membrane proteins involved in signal transduction, lysosomal acidification, and certain physiological processes related to mitochondria. The aspartic protease activity of PSN and the formation of a γ-secretase complex with other subunits such as nicastrin (NCT) are required for the biological functions. Although PSN is widely conserved in eukaryotes, most studies on PSN were conducted in metazoans. Homologous genes for PSN and NCT (EhPSN and EhNCT, respectively) are encoded in the genome of Entamoeba histolytica, however, their functions remain unknown. In this study, we showed that EhPSN and EhNCT form a complex on the cell membrane, demonstrating that the parasite possesses γ-secretase. The predicted structure of EhPSN was similar to the human homolog, demonstrated by the crystal structure, and phylogenetic analysis indicated good conservation between EhPSN and human PSN, supporting the premise that EhPSN functions as a subunit of γ-secretase. By contrast, EhNCT appears to have undergone remarkable structural changes during its evolution. Blue native-polyacrylamide gel electrophoresis combined with western blotting indicated that a 150-kDa single band contains both EhPSN (estimated molecular size: 47-kDa) and EhNCT (64-kDa), suggesting that the complex also contains other unknown components or post-translational modifications. Coimmunoprecipitation from amebic lysates also confirmed that EhPSN and EhNCT formed a complex. Indirect immunofluorescence analysis revealed that the complex localized to the plasma membrane. Moreover, EhPSN exhibited protease activity, which was suppressed by a γ-secretase inhibitor. This is the first report of a γ-secretase complex in protozoan parasites.
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Affiliation(s)
- Takashi Makiuchi
- Department of Infectious Diseases, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan.
| | - Yumiko Saito-Nakano
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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2
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Almeida MC, Eger SJ, He C, Audouard M, Nikitina A, Glasauer SMK, Han D, Mejía-Cupajita B, Acosta-Uribe J, Villalba-Moreno ND, Littau JL, Elcheikhali M, Rivera EK, Carrettiero DC, Villegas-Lanau CA, Sepulveda-Falla D, Lopera F, Kosik KS. Single-nucleus RNA sequencing demonstrates an autosomal dominant Alzheimer's disease profile and possible mechanisms of disease protection. Neuron 2024; 112:1778-1794.e7. [PMID: 38417436 PMCID: PMC11156559 DOI: 10.1016/j.neuron.2024.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 01/07/2024] [Accepted: 02/09/2024] [Indexed: 03/01/2024]
Abstract
Highly penetrant autosomal dominant Alzheimer's disease (ADAD) comprises a distinct disease entity as compared to the far more prevalent form of AD in which common variants collectively contribute to risk. The downstream pathways that distinguish these AD forms in specific cell types have not been deeply explored. We compared single-nucleus transcriptomes among a set of 27 cases divided among PSEN1-E280A ADAD carriers, sporadic AD, and controls. Autophagy genes and chaperones clearly defined the PSEN1-E280A cases compared to sporadic AD. Spatial transcriptomics validated the activation of chaperone-mediated autophagy genes in PSEN1-E280A. The PSEN1-E280A case in which much of the brain was spared neurofibrillary pathology and harbored a homozygous APOE3-Christchurch variant revealed possible explanations for protection from AD pathology including overexpression of LRP1 in astrocytes, increased expression of FKBP1B, and decreased PSEN1 expression in neurons. The unique cellular responses in ADAD and sporadic AD require consideration when designing clinical trials.
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Affiliation(s)
- Maria Camila Almeida
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Center for Natural and Humans Sciences, Federal University of ABC, Sao Bernardo do Campo, SP 09608020, Brazil
| | - Sarah J Eger
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Caroline He
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Morgane Audouard
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Arina Nikitina
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Stella M K Glasauer
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Dasol Han
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Barbara Mejía-Cupajita
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Grupo de Neurociencias de Antioquia, School of Medicine, Universidad de Antioquia, Medellín 050010, Colombia
| | - Juliana Acosta-Uribe
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Grupo de Neurociencias de Antioquia, School of Medicine, Universidad de Antioquia, Medellín 050010, Colombia
| | - Nelson David Villalba-Moreno
- Molecular Neuropathology of Alzheimer's Disease, Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Jessica Lisa Littau
- Molecular Neuropathology of Alzheimer's Disease, Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Megan Elcheikhali
- Department of Statistics and Applied Probability, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Erica Keane Rivera
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Daniel Carneiro Carrettiero
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Center for Natural and Humans Sciences, Federal University of ABC, Sao Bernardo do Campo, SP 09608020, Brazil
| | | | - Diego Sepulveda-Falla
- Molecular Neuropathology of Alzheimer's Disease, Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Francisco Lopera
- Grupo de Neurociencias de Antioquia, School of Medicine, Universidad de Antioquia, Medellín 050010, Colombia.
| | - Kenneth S Kosik
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
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3
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Guzmán-Ocampo DC, Aguayo-Ortiz R, Velasco-Bolom JL, Gupta PL, Roitberg AE, Dominguez L. Elucidating the Protonation State of the γ-Secretase Catalytic Dyad. ACS Chem Neurosci 2023; 14:261-269. [PMID: 36562727 DOI: 10.1021/acschemneuro.2c00563] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
γ-Secretase (GS) is an intramembrane aspartyl protease that participates in the sequential cleavage of C99 to generate different isoforms of the amyloid-β (Aβ) peptides that are associated with the development of Alzheimer's disease. Due to its importance in the proteolytic processing of C99 by GS, we performed pH replica exchange molecular dynamics (pH-REMD) simulations of GS in its apo and substrate-bound forms to sample the protonation states of the catalytic dyad. We found that the catalytic dyad is deprotonated at physiological pH in our apo form, but the presence of the substrate at the active site displaces its monoprotonated state toward physiological pH. Our results show that Asp257 acts as the general base and Asp385 as the general acid during the cleavage mechanism. We identified different amino acids such as Lys265, Arg269, and the PAL motif interacting with the catalytic dyad and promoting changes in its acid-base behavior. Finally, we also found a significant pKa shift of Glu280 related to the internalization of TM6-CT in the GS-apo form. Our study provides critical mechanistic insight into the GS mechanism and the basis for future research on the genesis of Aβ peptides and the development of Alzheimer's disease.
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Affiliation(s)
- Dulce C Guzmán-Ocampo
- Facultad de Química, Departamento de Fisicoquímica, Universidad Nacional Autónoma de México, Mexico City04510, Mexico
| | - Rodrigo Aguayo-Ortiz
- Facultad de Química, Departamento de Farmacia, Universidad Nacional Autónoma de México, Mexico City04510, Mexico
| | - José-Luis Velasco-Bolom
- Facultad de Química, Departamento de Fisicoquímica, Universidad Nacional Autónoma de México, Mexico City04510, Mexico
| | - Pancham Lal Gupta
- Department of Chemistry, University of Florida, Gainesville, Florida32611-7200, United States
| | - Adrian E Roitberg
- Department of Chemistry, University of Florida, Gainesville, Florida32611-7200, United States
| | - Laura Dominguez
- Facultad de Química, Departamento de Fisicoquímica, Universidad Nacional Autónoma de México, Mexico City04510, Mexico
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4
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Papadopoulou AA, Stelzer W, Silber M, Schlosser C, Spitz C, Haug-Kröper M, Straub T, Müller SA, Lichtenthaler SF, Muhle-Goll C, Langosch D, Fluhrer R. Helical stability of the GnTV transmembrane domain impacts on SPPL3 dependent cleavage. Sci Rep 2022; 12:20987. [PMID: 36470941 PMCID: PMC9722940 DOI: 10.1038/s41598-022-24772-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022] Open
Abstract
Signal-Peptide Peptidase Like-3 (SPPL3) is an intramembrane cleaving aspartyl protease that causes secretion of extracellular domains from type-II transmembrane proteins. Numerous Golgi-localized glycosidases and glucosyltransferases have been identified as physiological SPPL3 substrates. By SPPL3 dependent processing, glycan-transferring enzymes are deactivated inside the cell, as their active site-containing domain is cleaved and secreted. Thus, SPPL3 impacts on glycan patterns of many cellular and secreted proteins and can regulate protein glycosylation. However, the characteristics that make a substrate a favourable candidate for SPPL3-dependent cleavage remain unknown. To gain insights into substrate requirements, we investigated the function of a GxxxG motif located in the transmembrane domain of N-acetylglucosaminyltransferase V (GnTV), a well-known SPPL3 substrate. SPPL3-dependent secretion of the substrate's ectodomain was affected by mutations disrupting the GxxxG motif. Using deuterium/hydrogen exchange and NMR spectroscopy, we studied the effect of these mutations on the helix flexibility of the GnTV transmembrane domain and observed that increased flexibility facilitates SPPL3-dependent shedding and vice versa. This study provides first insights into the characteristics of SPPL3 substrates, combining molecular biology, biochemistry, and biophysical techniques and its results will provide the basis for better understanding the characteristics of SPPL3 substrates with implications for the substrates of other intramembrane proteases.
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Affiliation(s)
- Alkmini A. Papadopoulou
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Walter Stelzer
- grid.6936.a0000000123222966Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Mara Silber
- grid.7892.40000 0001 0075 5874Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany ,grid.7892.40000 0001 0075 5874Institute of Organic Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Christine Schlosser
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Charlotte Spitz
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Martina Haug-Kröper
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Tobias Straub
- grid.5252.00000 0004 1936 973XCore Facility Bioinformatics, Biomedical Center, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
| | - Stephan A. Müller
- grid.424247.30000 0004 0438 0426DZNE – German Center for Neurodegenerative Diseases, Munich, Germany
| | - Stefan F. Lichtenthaler
- grid.424247.30000 0004 0438 0426DZNE – German Center for Neurodegenerative Diseases, Munich, Germany ,grid.15474.330000 0004 0477 2438Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, 81675 Munich, Germany ,grid.452617.3Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Claudia Muhle-Goll
- grid.7892.40000 0001 0075 5874Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany ,grid.7892.40000 0001 0075 5874Institute of Organic Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Dieter Langosch
- grid.6936.a0000000123222966Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Regina Fluhrer
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
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5
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Catania M, Marti A, Rossi G, Fioretti A, Boiocchi C, Ricci M, Gasparini F, Beltrami D, Crepaldi V, Redaelli V, Giaccone G, Fede GD. The novel I213S mutation in PSEN1 gene is located in a hotspot codon associated with familial early-onset Alzheimer's disease. Neurobiol Aging 2022; 112:191-196. [DOI: 10.1016/j.neurobiolaging.2022.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 01/26/2022] [Indexed: 11/28/2022]
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6
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Papadopoulou AA, Fluhrer R. Signaling Functions of Intramembrane Aspartyl-Proteases. Front Cardiovasc Med 2020; 7:591787. [PMID: 33381526 PMCID: PMC7768045 DOI: 10.3389/fcvm.2020.591787] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 11/16/2020] [Indexed: 01/18/2023] Open
Abstract
Intramembrane proteolysis is more than a mechanism to "clean" the membranes from proteins no longer needed. By non-reversibly modifying transmembrane proteins, intramembrane cleaving proteases hold key roles in multiple signaling pathways and often distinguish physiological from pathological conditions. Signal peptide peptidase (SPP) and signal peptide peptidase-like proteases (SPPLs) recently have been associated with multiple functions in the field of signal transduction. SPP/SPPLs together with presenilins (PSs) are the only two families of intramembrane cleaving aspartyl proteases known in mammals. PS1 or PS2 comprise the catalytic center of the γ-secretase complex, which is well-studied in the context of Alzheimer's disease. The mammalian SPP/SPPL family of intramembrane cleaving proteases consists of five members: SPP and its homologous proteins SPPL2a, SPPL2b, SPPL2c, and SPPL3. Although these proteases were discovered due to their homology to PSs, it became evident in the past two decades that no physiological functions are shared between these two families. Based on studies in cell culture models various substrates of SPP/SPPL proteases have been identified in the past years and recently-developed mouse lines lacking individual members of this protease family, will help to further clarify the physiological functions of these proteases. In this review we concentrate on signaling roles of mammalian intramembrane cleaving aspartyl proteases. In particular, we will highlight the signaling roles of PS via its substrates NOTCH, VEGF, and others, mainly focusing on its involvement in vasculature. Delineating also signaling pathways that are affected and/or controlled by SPP/SPPL proteases. From SPP's participation in tumor progression and survival, to SPPL3's regulation of protein glycosylation and SPPL2c's control over cellular calcium stores, various crossovers between proteolytic activity of intramembrane proteases and cell signaling will be described.
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Affiliation(s)
- Alkmini A. Papadopoulou
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Augsburg, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Augsburg, Germany
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
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7
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Lechuga GC, Napoleão-Pêgo P, Bottino CCG, Pinho RT, Provance-Jr DW, De-Simone SG. Trypanosoma cruzi Presenilin-Like Transmembrane Aspartyl Protease: Characterization and Cellular Localization. Biomolecules 2020; 10:biom10111564. [PMID: 33212923 PMCID: PMC7698364 DOI: 10.3390/biom10111564] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/06/2020] [Accepted: 11/09/2020] [Indexed: 02/08/2023] Open
Abstract
The increasing detection of infections of Trypanosoma cruzi, the etiological agent of Chagas disease, in non-endemic regions beyond Latin America has risen to be a major public health issue. With an impact in the millions of people, current treatments rely on antiquated drugs that produce severe side effects and are considered nearly ineffective for the chronic phase. The minimal progress in the development of new drugs highlights the need for advances in basic research on crucial biochemical pathways in T. cruzi to identify new targets. Here, we report on the T. cruzi presenilin-like transmembrane aspartyl enzyme, a protease of the aspartic class in a unique phylogenetic subgroup with T. vivax separate from protozoans. Computational analyses suggest it contains nine transmembrane domains and an active site with the characteristic PALP motif of the A22 family. Multiple linear B-cell epitopes were identified by SPOT-synthesis analysis with Chagasic patient sera. Two were chosen to generate rabbit antisera, whose signal was primarily localized to the flagellar pocket, intracellular vesicles, and endoplasmic reticulum in parasites by whole-cell immunofluorescence. The results suggest that the parasitic presenilin-like enzyme could have a role in the secretory pathway and serve as a target for the generation of new therapeutics specific to the T. cruzi.
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Affiliation(s)
- Guilherme C. Lechuga
- Center for Technological Development in Health/National Institute of Science and Technology for Innovation on Diseases of Neglected Population (INCT-IDPN), FIOCRUZ, Rio de Janeiro 21040-900, Brazil; (G.C.L.); (P.N.-P.); (C.C.G.B.); (D.W.P.-J.)
- Cellular Ultrastructure Laboratory, FIOCRUZ, Oswaldo Cruz Institute, Rio de Janeiro 21040-900, Brazil
| | - Paloma Napoleão-Pêgo
- Center for Technological Development in Health/National Institute of Science and Technology for Innovation on Diseases of Neglected Population (INCT-IDPN), FIOCRUZ, Rio de Janeiro 21040-900, Brazil; (G.C.L.); (P.N.-P.); (C.C.G.B.); (D.W.P.-J.)
| | - Carolina C. G. Bottino
- Center for Technological Development in Health/National Institute of Science and Technology for Innovation on Diseases of Neglected Population (INCT-IDPN), FIOCRUZ, Rio de Janeiro 21040-900, Brazil; (G.C.L.); (P.N.-P.); (C.C.G.B.); (D.W.P.-J.)
| | - Rosa T. Pinho
- Clinical Immunology Laboratory, FIOCRUZ, Oswaldo Cruz Institute, Rio de Janeiro 21040-900, Brazil;
| | - David W. Provance-Jr
- Center for Technological Development in Health/National Institute of Science and Technology for Innovation on Diseases of Neglected Population (INCT-IDPN), FIOCRUZ, Rio de Janeiro 21040-900, Brazil; (G.C.L.); (P.N.-P.); (C.C.G.B.); (D.W.P.-J.)
- Interdisciplinary Medical Research Laboratory, FIOCRUZ, Oswaldo Cruz Institute, Rio de Janeiro 21040-900, Brazil
| | - Salvatore G. De-Simone
- Center for Technological Development in Health/National Institute of Science and Technology for Innovation on Diseases of Neglected Population (INCT-IDPN), FIOCRUZ, Rio de Janeiro 21040-900, Brazil; (G.C.L.); (P.N.-P.); (C.C.G.B.); (D.W.P.-J.)
- Department of Molecular and Cellular Biology, Federal Fluminense University, Niterói 24220-008, Brazil
- Correspondence: ; Tel.: +55-21-3865-8183
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Effect of changes at the conserved + 3 position of mature archaellins on in vitro cleavage by the pre-archaellin peptidase FlaK of Methanococcus maripaludis. Arch Microbiol 2020; 202:1669-1675. [PMID: 32285165 DOI: 10.1007/s00203-020-01873-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/28/2020] [Accepted: 04/01/2020] [Indexed: 10/24/2022]
Abstract
Archaea swim using archaella that are domain-specific rotary type IV pilus-like appendages. The structural components of the archaellum filament are archaellins, initially made as preproteins with type IV pilin-like signal peptides which are removed by signal peptidases that are homologues of prepilin peptidases that remove signal peptides from type IV pilins. N-terminal sequences of archaellins, including the signal peptide cleavage site, are conserved and various positions have been previously shown to be critical for signal peptide removal. Archaellins have an absolute conservation of glycine at the + 3 position from the signal peptide cleavage site. To investigate its role in signal peptide cleavage, I used archaellin variants in which the + 3 glycine was mutated to all other possibilities in in vitro cleavage reactions. Cleavage was observed with ten different amino acids at the + 3 position, indicating that the observed glycine conservation is not required for this essential processing step.
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9
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Galla L, Redolfi N, Pozzan T, Pizzo P, Greotti E. Intracellular Calcium Dysregulation by the Alzheimer's Disease-Linked Protein Presenilin 2. Int J Mol Sci 2020; 21:E770. [PMID: 31991578 PMCID: PMC7037278 DOI: 10.3390/ijms21030770] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/17/2020] [Accepted: 01/21/2020] [Indexed: 12/18/2022] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia. Even though most AD cases are sporadic, a small percentage is familial due to autosomal dominant mutations in amyloid precursor protein (APP), presenilin-1 (PSEN1), and presenilin-2 (PSEN2) genes. AD mutations contribute to the generation of toxic amyloid β (Aβ) peptides and the formation of cerebral plaques, leading to the formulation of the amyloid cascade hypothesis for AD pathogenesis. Many drugs have been developed to inhibit this pathway but all these approaches currently failed, raising the need to find additional pathogenic mechanisms. Alterations in cellular calcium (Ca2+) signaling have also been reported as causative of neurodegeneration. Interestingly, Aβ peptides, mutated presenilin-1 (PS1), and presenilin-2 (PS2) variously lead to modifications in Ca2+ homeostasis. In this contribution, we focus on PS2, summarizing how AD-linked PS2 mutants alter multiple Ca2+ pathways and the functional consequences of this Ca2+ dysregulation in AD pathogenesis.
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Affiliation(s)
- Luisa Galla
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy; (L.G.); (N.R.); (T.P.); (E.G.)
- Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy
| | - Nelly Redolfi
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy; (L.G.); (N.R.); (T.P.); (E.G.)
| | - Tullio Pozzan
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy; (L.G.); (N.R.); (T.P.); (E.G.)
- Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy
- Venetian Institute of Molecular Medicine (VIMM), 35131 Padua, Italy
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy; (L.G.); (N.R.); (T.P.); (E.G.)
- Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy
| | - Elisa Greotti
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy; (L.G.); (N.R.); (T.P.); (E.G.)
- Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy
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10
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Barniol-Xicota M, Verhelst SHL. Isolation of intramembrane proteases in membrane-like environments. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183193. [PMID: 31945321 DOI: 10.1016/j.bbamem.2020.183193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/07/2020] [Accepted: 01/10/2020] [Indexed: 12/24/2022]
Abstract
Intramembrane proteases (IMPs) are proteolytic enzymes embedded in the lipid bilayer, where they cleave transmembrane substrates. The importance of IMPs relies on their role in a wide variety of cellular processes and diseases. In order to study the activity and function of IMPs, their purified form is often desired. The production of pure and active IMPs has proven to be a challenging task. This process unavoidably requires the use of solubilizing agents that will, to some extent, alter the native environment of these proteases. In this review we present the current solubilization and reconstitution techniques that have been applied to IMPs. In addition, we describe how these techniques had an influence on the activity and structural studies of IMPs, focusing on rhomboid proteases and γ-secretase.
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Affiliation(s)
- Marta Barniol-Xicota
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestraat 49, Box 802, B-3000, Belgium.
| | - Steven H L Verhelst
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestraat 49, Box 802, B-3000, Belgium; Leibniz Institute for Analytical Sciences, ISAS, e.V., Otto-Hahn-Str. 6b, 44227 Dortmund, Germany.
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11
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Sharma D, Otto G, Warren EC, Beesley P, King JS, Williams RSB. Gamma secretase orthologs are required for lysosomal activity and autophagic degradation in Dictyostelium discoideum, independent of PSEN (presenilin) proteolytic function. Autophagy 2019; 15:1407-1418. [PMID: 30806144 PMCID: PMC6613883 DOI: 10.1080/15548627.2019.1586245] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mutations in the γ-secretase complex are strongly associated with familial Alzheimer disease. Both proteolytic and non-proteolytic functions for the γ-secretase complex have been previously described in mammalian model organisms, but their relative contributions to disease pathology remain unclear. Here, we dissect the roles of orthologs of the γ-secretase components in the model system Dictyostelium, focusing on endocytosis, lysosomal activity and autophagy. In this model, we show that the orthologs of PSEN (psenA and psenB), Ncstn (nicastrin) and Aph-1 (gamma-secretase subunit Aph-1), are necessary for optimal fluid-phase uptake by macropinocytosis and in multicellular development under basic pH conditions. Disruption of either psenA/B or Aph-1 proteins also leads to disrupted phagosomal proteolysis as well as decreased autophagosomal acidification and autophagic flux. This indicates a general defect in lysosomal trafficking and degradation, which we show leads to the accumulation of ubiquitinated protein aggregates in cells lacking psenA/B and Aph-1 proteins. Importantly, we find that all the endocytic defects observed in Dictyostelium PSEN ortholog mutants can be fully rescued by proteolytically inactive Dictyostelium psenB and human PSEN1 proteins. Our data therefore demonstrates an evolutionarily conserved non-proteolytic role for presenilin, and γ-secretase component orthologs, in maintaining Dictyostelium lysosomal trafficking and autophagy. Abbreviations: Atg8: autophagy protein 8a; Aph-1: gamma-secretase subunit Aph-1; crtA: calreticulin; ER: endoplasmic reticulum; GFP: green fluorescent protein; GSK3B: glycogen synthase kinase 3 beta; Ncstn: nicastrin; PSEN1: presenilin 1; psenA and psenB: Dictyostelium presenilin A and B; TRITC; tetramethylrhodamine isothiocyanate.
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Affiliation(s)
- Devdutt Sharma
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Grant Otto
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Eleanor C Warren
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Philip Beesley
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
| | - Jason S King
- b Department of Biomedical Sciences , University of Sheffield , Sheffield , UK
| | - Robin S B Williams
- a School of Biological Sciences , Royal Holloway, University of London , Egham , UK
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12
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Oikawa N, Walter J. Presenilins and γ-Secretase in Membrane Proteostasis. Cells 2019; 8:cells8030209. [PMID: 30823664 PMCID: PMC6468700 DOI: 10.3390/cells8030209] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 02/26/2019] [Accepted: 02/27/2019] [Indexed: 12/20/2022] Open
Abstract
The presenilin (PS) proteins exert a crucial role in the pathogenesis of Alzheimer disease (AD) by mediating the intramembranous cleavage of amyloid precursor protein (APP) and the generation of amyloid β-protein (Aβ). The two homologous proteins PS1 and PS2 represent the catalytic subunits of distinct γ-secretase complexes that mediate a variety of cellular processes, including membrane protein metabolism, signal transduction, and cell differentiation. While the intramembrane cleavage of select proteins by γ-secretase is critical in the regulation of intracellular signaling pathways, the plethora of identified protein substrates could also indicate an important role of these enzyme complexes in membrane protein homeostasis. In line with this notion, PS proteins and/or γ-secretase has also been implicated in autophagy, a fundamental process for the maintenance of cellular functions and homeostasis. Dysfunction in the clearance of proteins in the lysosome and during autophagy has been shown to contribute to neurodegeneration. This review summarizes the recent knowledge about the role of PS proteins and γ-secretase in membrane protein metabolism and trafficking, and the functional relation to lysosomal activity and autophagy.
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Affiliation(s)
- Naoto Oikawa
- Department of Neurology, University of Bonn, 53127 Bonn, Germany.
| | - Jochen Walter
- Department of Neurology, University of Bonn, 53127 Bonn, Germany.
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13
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Naing SH, Kalyoncu S, Smalley DM, Kim H, Tao X, George JB, Jonke AP, Oliver RC, Urban VS, Torres MP, Lieberman RL. Both positional and chemical variables control in vitro proteolytic cleavage of a presenilin ortholog. J Biol Chem 2018; 293:4653-4663. [PMID: 29382721 DOI: 10.1074/jbc.ra117.001436] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 01/23/2018] [Indexed: 11/06/2022] Open
Abstract
Mechanistic details of intramembrane aspartyl protease (IAP) chemistry, which is central to many biological and pathogenic processes, remain largely obscure. Here, we investigated the in vitro kinetics of a microbial intramembrane aspartyl protease (mIAP) fortuitously acting on the renin substrate angiotensinogen and the C-terminal transmembrane segment of amyloid precursor protein (C100), which is cleaved by the presenilin subunit of γ-secretase, an Alzheimer disease (AD)-associated IAP. mIAP variants with substitutions in active-site and putative substrate-gating residues generally exhibit impaired, but not abolished, activity toward angiotensinogen and retain the predominant cleavage site (His-Thr). The aromatic ring, but not the hydroxyl substituent, within Tyr of the catalytic Tyr-Asp (YD) motif plays a catalytic role, and the hydrolysis reaction incorporates bulk water as in soluble aspartyl proteases. mIAP hydrolyzes the transmembrane region of C100 at two major presenilin cleavage sites, one corresponding to the AD-associated Aβ42 peptide (Ala-Thr) and the other to the non-pathogenic Aβ48 (Thr-Leu). For the former site, we observed more favorable kinetics in lipid bilayer-mimicking bicelles than in detergent solution, indicating that substrate-lipid and substrate-enzyme interactions both contribute to catalytic rates. High-resolution MS analyses across four substrates support a preference for threonine at the scissile bond. However, results from threonine-scanning mutagenesis of angiotensinogen demonstrate a competing positional preference for cleavage. Our results indicate that IAP cleavage is controlled by both positional and chemical factors, opening up new avenues for selective IAP inhibition for therapeutic interventions.
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Affiliation(s)
- Swe-Htet Naing
- School of Chemistry and Biochemistry, Atlanta, Georgia 30332
| | - Sibel Kalyoncu
- School of Chemistry and Biochemistry, Atlanta, Georgia 30332
| | - David M Smalley
- Petit Institute for Bioengineering and Biosciences, Atlanta, Georgia 30332
| | - Hyojung Kim
- School of Chemistry and Biochemistry, Atlanta, Georgia 30332; School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Xingjian Tao
- School of Chemistry and Biochemistry, Atlanta, Georgia 30332
| | - Josh B George
- School of Chemistry and Biochemistry, Atlanta, Georgia 30332
| | - Alex P Jonke
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Ryan C Oliver
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Volker S Urban
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Matthew P Torres
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
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14
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Allosteric Modulation of Intact γ-Secretase Structural Dynamics. Biophys J 2018; 113:2634-2649. [PMID: 29262358 DOI: 10.1016/j.bpj.2017.10.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 09/26/2017] [Accepted: 10/10/2017] [Indexed: 12/20/2022] Open
Abstract
As a protease complex involved in the cleavage of amyloid precursor proteins that lead to the formation of amyloid β fibrils implicated in Alzheimer's disease, γ-secretase is an important target for developing therapeutics against Alzheimer's disease. γ-secretase is composed of four subunits: nicastrin (NCT) in the extracellular (EC) domain, presenilin-1 (PS1), anterior pharynx defective 1, and presenilin enhancer 2 in the transmembrane (TM) domain. NCT and PS1 play important roles in binding amyloid β precursor proteins and modulating PS1 catalytic activity. Yet, the molecular mechanisms of coupling between substrate/modulator binding and catalytic activity remain to be elucidated. Recent determination of intact human γ-secretase cryo-electron microscopy structure has opened the way for a detailed investigation of the structural dynamics of this complex. Our analysis, based on a membrane-coupled anisotropic network model, reveals two types of NCT motions, bending and twisting, with respect to PS1. These underlie the fluctuations between the "open" and "closed" states of the lid-like NCT with respect to a hydrophilic loop 1 (HL1) on PS1, thus allowing or blocking access of the substrate peptide (EC portion) to HL1 and to the neighboring helix TM2. In addition to this alternating access mechanism, fluctuations in the volume of the PS1 central cavity facilitate the exposure of the catalytic site for substrate cleavage. Druggability simulations show that γ-secretase presents several hot spots for either orthosteric or allosteric inhibition of catalytic activity, consistent with experimental data. In particular, a hinge region at the interface between the EC and TM domains, near the interlobe groove of NCT, emerges as an allo-targeting site that would impact the coupling between HL1/TM2 and the catalytic pocket, opening, to our knowledge, new avenues for structure-based design of novel allosteric modulators of γ-secretase protease activity.
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15
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Williamson RL, Laulagnier K, Miranda AM, Fernandez MA, Wolfe MS, Sadoul R, Di Paolo G. Disruption of amyloid precursor protein ubiquitination selectively increases amyloid β (Aβ) 40 levels via presenilin 2-mediated cleavage. J Biol Chem 2017; 292:19873-19889. [PMID: 29021256 PMCID: PMC5712626 DOI: 10.1074/jbc.m117.818138] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 09/30/2017] [Indexed: 11/06/2022] Open
Abstract
Amyloid plaques, a neuropathological hallmark of Alzheimer's disease, are largely composed of amyloid β (Aβ) peptide, derived from cleavage of amyloid precursor protein (APP) by β- and γ-secretases. The endosome is increasingly recognized as an important crossroad for APP and these secretases, with major implications for APP processing and amyloidogenesis. Among various post-translational modifications affecting APP accumulation, ubiquitination of cytodomain lysines may represent a key signal controlling APP endosomal sorting. Here, we show that substitution of APP C-terminal lysines with arginine disrupts APP ubiquitination and that an increase in the number of substituted lysines tends to increase APP metabolism. An APP mutant lacking all C-terminal lysines underwent the most pronounced increase in processing, leading to accumulation of both secreted and intracellular Aβ40. Artificial APP ubiquitination with rapalog-mediated proximity inducers reduced Aβ40 generation. A lack of APP C-terminal lysines caused APP redistribution from endosomal intraluminal vesicles (ILVs) to the endosomal limiting membrane, with a subsequent decrease in APP C-terminal fragment (CTF) content in secreted exosomes, but had minimal effects on APP lysosomal degradation. Both the increases in secreted and intracellular Aβ40 were abolished by depletion of presenilin 2 (PSEN2), recently shown to be enriched on the endosomal limiting membrane compared with PSEN1. Our findings demonstrate that ubiquitin can act as a signal at five cytodomain-located lysines for endosomal sorting of APP. They further suggest that disruption of APP endosomal sorting reduces its sequestration in ILVs and results in PSEN2-mediated processing of a larger pool of APP-CTF on the endosomal membrane.
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Affiliation(s)
| | - Karine Laulagnier
- the Grenoble Institut des Neurosciences, Inserm, Grenoble 38042, France
| | - André M Miranda
- From the Department of Pathology and Cell Biology and
- the Life and Health Sciences Research Institute, School of Medicine, University of Minho and
- Life and Health Sciences Research Institute/3B's Research Group-Biomaterials, Biodegradables, and Biomimetics Associate Laboratory, 4710-057 Braga/Guimarães, Portugal, and
| | - Marty A Fernandez
- the Center for Neurologic Diseases, Harvard University, Boston, Massachusetts 02115
| | - Michael S Wolfe
- the Center for Neurologic Diseases, Harvard University, Boston, Massachusetts 02115
| | - Rémy Sadoul
- the Grenoble Institut des Neurosciences, Inserm, Grenoble 38042, France
| | - Gilbert Di Paolo
- From the Department of Pathology and Cell Biology and
- the Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, New York 10032
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16
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Johnson DS, Li YM, Pettersson M, St George-Hyslop PH. Structural and Chemical Biology of Presenilin Complexes. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a024067. [PMID: 28320827 PMCID: PMC5710098 DOI: 10.1101/cshperspect.a024067] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The presenilin proteins are the catalytic subunits of a tetrameric complex containing presenilin 1 or 2, anterior pharynx defective 1 (APH1), nicastrin, and PEN-2. Other components such as TMP21 may exist in a subset of specialized complexes. The presenilin complex is the founding member of a unique class of aspartyl proteases that catalyze the γ, ɛ, ζ site cleavage of the transmembrane domains of Type I membrane proteins including amyloid precursor protein (APP) and Notch. Here, we detail the structural and chemical biology of this unusual enzyme. Taken together, these studies suggest that the complex exists in several conformations, and subtle long-range (allosteric) shifts in the conformation of the complex underpin substrate access to the catalytic site and the mechanism of action for allosteric inhibitors and modulators. Understanding the mechanics of these shifts will facilitate the design of γ-secretase modulator (GSM) compounds that modulate the relative efficiency of γ, ɛ, ζ site cleavage and/or substrate specificity.
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Affiliation(s)
- Douglas S. Johnson
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts 02139
| | - Yue-Ming Li
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065
| | - Martin Pettersson
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts 02139
| | - Peter H. St George-Hyslop
- Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrookes Hospital, Cambridge CB2 0XY, United Kingdom,Tanz Centre for Research in Neurodegenerative Diseases and Departments of Medicine, Laboratory Medicine and Pathobiology, and Medical Biophysics, University of Toronto, Toronto, Ontario M5T 2S8, Canada
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17
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Somavarapu AK, Kepp KP. Membrane Dynamics of γ-Secretase Provides a Molecular Basis for β-Amyloid Binding and Processing. ACS Chem Neurosci 2017; 8:2424-2436. [PMID: 28841371 DOI: 10.1021/acschemneuro.7b00208] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
γ-Secretase produces β-amyloid (Aβ) within its presenilin (PS1) subunit, mutations in which cause Alzheimer's disease, and current therapies thus seek to modulate its activity. While the general structure is known from recent electron microscopy studies, direct loop and membrane interactions and explicit dynamics relevant to substrate processing remain unknown. We report a modeled structure utilizing the optimal multitemplate information available, including loops and missing side chains, account of maturation cleavage, and explicit all-atom molecular dynamics in the membrane. We observe three distinct conformations of γ-secretase (open, semiopen, and closed) that remarkably differ by tilting of helices 2 and 3 of PS1, directly controlling active site availability. The large hydrophilic loop of PS1 where maturation occurs reveals a new helix segment that parallels the likely helix character of other substrates. The semiopen conformation consistently shows the best fit of Aβ peptides, that is, longer residence before release and by inference more trimming. In contrast, the closed, hydrophobic conformation is largely inactive and the open conformation is active but provides fewer optimal interactions and induces shorter residence time and by inference releases Aβ peptides of longer lengths. Our simulations thus provide a molecular basis for substrate processing and changes in the Aβ42/Aβ40 ratio. Accordingly, selective binding to protect the semiopen "innocent" conformation provides a molecular recipe for effective γ-secretase modulators; we provide the full atomic structures for these states that may play a key role in developing selective γ-secretase modulators for treatment of Alzheimer's disease.
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Affiliation(s)
| | - Kasper P. Kepp
- Technical University of Denmark, DTU Chemistry, DK-2800 Kongens Lyngby, Denmark
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18
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Distinct amyloid precursor protein processing machineries of the olfactory system. Biochem Biophys Res Commun 2017; 495:533-538. [PMID: 29097202 DOI: 10.1016/j.bbrc.2017.10.153] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 10/28/2017] [Indexed: 11/21/2022]
Abstract
Processing of amyloid precursor protein (APP) occurs through sequential cleavages first by β-secretase and then by the γ-secretase complex. However, abnormal processing of APP leads to excessive production of β-amyloid (Aβ) in the central nervous system (CNS), an event which is regarded as a primary cause of Alzheimer's disease (AD). In particular, gene mutations of the γ-secretase complex-which contains presenilin 1 or 2 as the catalytic core-could trigger marked Aβ accumulation. Olfactory dysfunction usually occurs before the onset of typical AD-related symptoms (eg, memory loss or muscle retardation), suggesting that the olfactory system may be one of the most vulnerable regions to AD. To date however, little is known about why the olfactory system is affected so early by AD prior to other regions. Thus, we examined the distribution of secretases and levels of APP processing in the olfactory system under either healthy or pathological conditions. Here, we show that the olfactory system has distinct APP processing machineries. In particular, we identified higher expressions levels and activity of γ-secretase in the olfactory epithelium (OE) than other regions of the brain. Moreover, APP c-terminal fragments (CTF) are markedly detected. During AD progression, we note increased expression of presenilin2 of γ-secretases in the OE, not in the OB, and show that neurotoxic Aβ*56 accumulates more quickly in the OE. Taken together, these results suggest that the olfactory system has distinct APP processing machineries under healthy and pathological conditions. This finding may provide a crucial understanding of the unique APP-processing mechanisms in the olfactory system, and further highlights the correlation between olfactory deficits and AD symptoms.
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19
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Otoguro T, Tanaka T, Kasai H, Yamashita A, Moriishi K. Inhibitory effect of presenilin inhibitor LY411575 on maturation of hepatitis C virus core protein, production of the viral particle and expression of host proteins involved in pathogenicity. Microbiol Immunol 2017; 60:740-753. [PMID: 27797115 DOI: 10.1111/1348-0421.12448] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 10/20/2016] [Accepted: 10/26/2016] [Indexed: 12/12/2022]
Abstract
Hepatitis C virus (HCV) core protein is responsible for the formation of infectious viral particles and induction of pathogenicity. The C-terminal transmembrane region of the immature core protein is cleaved by signal peptide peptidase (SPP) for maturation of the core protein. SPP belongs to the family of presenilin-like aspartic proteases. Some presenilin inhibitors are expected to suppress HCV infection and production; however, this anti-HCV effect has not been investigated in detail. In this study, presenilin inhibitors were screened to identify anti-HCV compounds. Of the 13 presenilin inhibitors tested, LY411575 was the most potent inhibitor of SPP-dependent cleavage of HCV core protein. Production of intracellular core protein and supernatant infectious viral particles from HCV-infected cells was significantly impaired by LY411575 in a dose-dependent manner (half maximum inhibitory concentration = 0.27 μM, cytotoxic concentration of the extracts to cause death to 50% of viable cells > 10 μM). No effect of LY411575 on intracellular HCV RNA in the subgenomic replicon cells was detected. LY411575 synergistically promoted daclatasvir-dependent inhibition of viral production, but not that of viral replication. Furthermore, LY411575 inhibited HCV-related production of reactive oxygen species and expression of NADPH oxidases and vascular endothelial growth factor. Taken together, our data suggest that LY411575 suppresses HCV propagation through SPP inhibition and impairs host gene expressions related to HCV pathogenicity.
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Affiliation(s)
- Teruhime Otoguro
- Department of Microbiology, Graduate School of Medical Science, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi 409-3898, Japan
| | - Tomohisa Tanaka
- Department of Microbiology, Graduate School of Medical Science, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi 409-3898, Japan
| | - Hirotake Kasai
- Department of Microbiology, Graduate School of Medical Science, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi 409-3898, Japan
| | - Atsuya Yamashita
- Department of Microbiology, Graduate School of Medical Science, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi 409-3898, Japan
| | - Kohji Moriishi
- Department of Microbiology, Graduate School of Medical Science, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi 409-3898, Japan
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20
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Presenilin 2 deficiency facilitates Aβ-induced neuroinflammation and injury by upregulating P2X7 expression. SCIENCE CHINA-LIFE SCIENCES 2017; 60:189-201. [DOI: 10.1007/s11427-016-0347-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 12/16/2016] [Indexed: 12/12/2022]
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21
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Kepp KP. Alzheimer's disease due to loss of function: A new synthesis of the available data. Prog Neurobiol 2016; 143:36-60. [PMID: 27327400 DOI: 10.1016/j.pneurobio.2016.06.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 06/10/2016] [Accepted: 06/11/2016] [Indexed: 12/11/2022]
Abstract
Alzheimer's Disease (AD) is a highly complex disease involving a broad range of clinical, cellular, and biochemical manifestations that are currently not understood in combination. This has led to many views of AD, e.g. the amyloid, tau, presenilin, oxidative stress, and metal hypotheses. The amyloid hypothesis has dominated the field with its assumption that buildup of pathogenic β-amyloid (Aβ) peptide causes disease. This paradigm has been criticized, yet most data suggest that Aβ plays a key role in the disease. Here, a new loss-of-function hypothesis is synthesized that accounts for the anomalies of the amyloid hypothesis, e.g. the curious pathogenicity of the Aβ42/Aβ40 ratio, the loss of Aβ caused by presenilin mutation, the mixed phenotypes of APP mutations, the poor clinical-biochemical correlations for genetic variant carriers, and the failure of Aβ reducing drugs. The amyloid-loss view accounts for recent findings on the structure and chemical features of Aβ variants and their coupling to human patient data. The lost normal function of APP/Aβ is argued to be metal transport across neuronal membranes, a view with no apparent anomalies and substantially more explanatory power than the gain-of-function amyloid hypothesis. In the loss-of-function scenario, the central event of Aβ aggregation is interpreted as a loss of soluble, functional monomer Aβ rather than toxic overload of oligomers. Accordingly, new research models and treatment strategies should focus on remediation of the functional amyloid balance, rather than strict containment of Aβ, which, for reasons rationalized in this review, has failed clinically.
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Affiliation(s)
- Kasper P Kepp
- Technical University of Denmark, DTU Chemistry, DK-2800 Kongens Lyngby, Denmark.
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22
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Piccoli E, Rossi G, Rossi T, Pelliccioni G, D'Amato I, Tagliavini F, Di Fede G. Novel PSEN1 mutations (H214N and R220P) associated with familial Alzheimer's disease identified by targeted exome sequencing. Neurobiol Aging 2016; 40:192.e7-192.e11. [PMID: 26925509 DOI: 10.1016/j.neurobiolaging.2016.01.134] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/30/2015] [Accepted: 01/30/2016] [Indexed: 01/21/2023]
Abstract
Autosomal dominant Alzheimer's disease (AD) is caused by mutations in amyloid precursor protein, presenilin 1 (PSEN1), and presenilin 2 genes and is mostly associated with early-onset form of AD (EOAD), whereas very few mutations were also found in late-onset AD (LOAD) cases. Because of the clinical overlapping between AD and other degenerative dementias such as frontotemporal dementias, a wide-spectrum genetic analysis should be envisaged in the differential diagnosis of this group of disorders. We used next-generation sequencing techniques to analyze 10 genes involved in dementia on a cohort of 20 EOAD and 20 LOAD cases. We found 5 rare coding variants (frequency <1%). PSEN1 H214N mutation, identified in a case of familial EOAD and PSEN1 R220P, found in a case of familial LOAD, are predicted to be pathogenic. These findings confirm the contribution of PSEN1 genetic variants also to LOAD, underlining the need of extending the genetic screening of presenilin mutations to LOAD patients. Two variants in microtubule-associated protein tau and 1 in progranulin appeared to be benign polymorphisms, showing no major contribution of these genes to AD.
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Affiliation(s)
- Elena Piccoli
- Division of Neurology V and Neuropathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Giacomina Rossi
- Division of Neurology V and Neuropathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy.
| | - Tommaso Rossi
- Division of Neurology, Geriatric Hospital, INRCA IRCCS, Ancona, Italy
| | | | - Ilaria D'Amato
- Division of Neurology V and Neuropathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Fabrizio Tagliavini
- Division of Neurology V and Neuropathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Giuseppe Di Fede
- Division of Neurology V and Neuropathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
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23
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Somavarapu AK, Kepp KP. Loss of stability and hydrophobicity of presenilin 1 mutations causing Alzheimer's disease. J Neurochem 2016; 137:101-11. [PMID: 26756738 DOI: 10.1111/jnc.13535] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 12/23/2015] [Accepted: 12/29/2015] [Indexed: 12/15/2022]
Abstract
Nearly 200 mutations in the gene coding for presenilin 1 (PSEN1) cause early-onset Alzheimer's disease, yet the molecular mechanism remains obscure. As a meta-analysis, we compiled available clinical and biochemical data for PSEN1 variants and correlated these to chemical properties of the mutants. We found statistically significant relationships between relative Aβ42 levels and clinical age of onset. We then computed chemical properties of the mutants from a variety of computational chemistry tools. Relative Aβ42 levels correlated significantly (95% confidence or more from p-values of linear regression) with loss of hydrophobicity for four different regression analyses (squared correlation coefficient of linear regression R(2) of 0.41-0.53) and with increased polarity (R(2) = 0.47, 0.59) and loss of protein stability (R(2) = 0.39, 0.63) for two independent data sets. Age of onset of patients carrying PSEN1 variants correlated with increased polarity (R(2) = 0.49, 0.40) and loss of stability (R(2) = 0.75, 0.44) of the protein for both data sets. These relations suggest that mutants impair the membrane-associated structural integrity of presenilin by reducing hydrophobic membrane association and overall protein stability. This explains why the many mutations that spread out across the protein and far from the catalytic aspartates can cause disease. The identified molecular determinants of clinical age of symptom onset may be relevant to future presenilin-modulating therapies specifically directed towards increasing the structural integrity and packing of the protein. Close to 200 mutations in presenilin 1 (PSEN1) cause Alzheimer's disease, but the biochemical relating these to disease remains debated. The chemical properties of PSEN1 variants were computed and correlated against clinical age of symptom onset. Loss of stability and hydrophobicity and gain of polarity relate to disease onset, suggesting that mutants impair the membrane structure of PSEN1 and that therapies should increase PSEN1 structural integrity.
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Affiliation(s)
| | - Kasper P Kepp
- Technical University of Denmark, DTU Chemistry, Kongens Lyngby, Denmark
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24
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Fornetti J, Flanders KC, Henson PM, Tan AC, Borges VF, Schedin P. Mammary epithelial cell phagocytosis downstream of TGF-β3 is characterized by adherens junction reorganization. Cell Death Differ 2015; 23:185-96. [PMID: 26113040 PMCID: PMC4716300 DOI: 10.1038/cdd.2015.82] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 03/31/2015] [Accepted: 05/14/2015] [Indexed: 01/17/2023] Open
Abstract
After weaning, during mammary gland involution, milk-producing mammary epithelial cells undergo apoptosis. Effective clearance of these dying cells is essential, as persistent apoptotic cells have a negative impact on gland homeostasis, future lactation and cancer susceptibility. In mice, apoptotic cells are cleared by the neighboring epithelium, yet little is known about how mammary epithelial cells become phagocytic or whether this function is conserved between species. Here we use a rat model of weaning-induced involution and involuting breast tissue from women, to demonstrate apoptotic cells within luminal epithelial cells and epithelial expression of the scavenger mannose receptor, suggesting conservation of phagocytosis by epithelial cells. In the rat, epithelial transforming growth factor-β (TGF-β) signaling is increased during involution, a pathway known to promote phagocytic capability. To test whether TGF-β enhances the phagocytic ability of mammary epithelial cells, non-transformed murine mammary epithelial EpH4 cells were cultured to achieve tight junction impermeability, such as occurs during lactation. TGF-β3 treatment promoted loss of tight junction impermeability, reorganization and cleavage of the adherens junction protein E-cadherin (E-cad), and phagocytosis. Phagocytosis correlated with junction disruption, suggesting junction reorganization is necessary for phagocytosis by epithelial cells. Supporting this hypothesis, epithelial cell E-cad reorganization and cleavage were observed in rat and human involuting mammary glands. Further, in the rat, E-cad cleavage correlated with increased γ-secretase activity and β-catenin nuclear localization. In vitro, pharmacologic inhibitors of γ-secretase or β-catenin reduced the effect of TGF-β3 on phagocytosis to near baseline levels. However, β-catenin signaling through LiCl treatment did not enhance phagocytic capacity, suggesting a model in which both reorganization of cell junctions and β-catenin signaling contribute to phagocytosis downstream of TGF-β3. Our data provide insight into how mammary epithelial cells contribute to apoptotic cell clearance, and in light of the negative consequences of impaired apoptotic cell clearance during involution, may shed light on involution-associated breast pathologies.
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Affiliation(s)
- J Fornetti
- Program in Reproductive Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.,Program in Immunobiology and Cancer, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - K C Flanders
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, Bethesda, MD, USA
| | - P M Henson
- Program in Reproductive Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.,Department of Pediatrics, National Jewish Health, Denver, CO, USA.,Integrated Department of Immunology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - A-C Tan
- Department of Medicine, Division of Medical Oncology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - V F Borges
- Department of Medicine, Division of Medical Oncology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.,Young Women's Breast Cancer Translational Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - P Schedin
- Young Women's Breast Cancer Translational Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.,Knight Cancer Institute and Department of Cell, Developmental & Cancer Biology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, USA
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25
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Langosch D, Scharnagl C, Steiner H, Lemberg MK. Understanding intramembrane proteolysis: from protein dynamics to reaction kinetics. Trends Biochem Sci 2015; 40:318-27. [PMID: 25941170 DOI: 10.1016/j.tibs.2015.04.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 12/12/2022]
Abstract
Intramembrane proteolysis - cleavage of proteins within the plane of a membrane - is a widespread phenomenon that can contribute to the functional activation of substrates and is involved in several diseases. Although different families of intramembrane proteases have been discovered and characterized, we currently do not know how these enzymes discriminate between substrates and non-substrates, how site-specific cleavage is achieved, or which factors determine the rate of proteolysis. Focusing on γ-secretase and rhomboid proteases, we argue that answers to these questions may emerge from connecting experimental readouts, such as reaction kinetics and the determination of cleavage sites, to the structures and the conformational dynamics of substrates and enzymes.
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Affiliation(s)
- D Langosch
- Technische Universität München, Lehrstuhl Chemie der Biopolymere, Weihenstephaner Berg 3, 85354 Freising, and Munich Center for Integrated Protein Science (CIMPS(M)), Germany.
| | - C Scharnagl
- Fakultät für Physik E14, Technische Universität München, Maximus-von-Imhof-Forum 4, 85354 Freising, Germany
| | - H Steiner
- Ludwig-Maximilians-University Munich, Metabolic Biochemistry and DZNE (German Center for Neurodegenerative Diseases), Munich, Germany
| | - M K Lemberg
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Deutsches Krebsforschungszentrum (DKFZ)-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
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26
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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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27
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Porquet D, Andrés-Benito P, Griñán-Ferré C, Camins A, Ferrer I, Canudas AM, Del Valle J, Pallàs M. Amyloid and tau pathology of familial Alzheimer's disease APP/PS1 mouse model in a senescence phenotype background (SAMP8). AGE (DORDRECHT, NETHERLANDS) 2015; 37:9747. [PMID: 25663420 PMCID: PMC4320125 DOI: 10.1007/s11357-015-9747-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 01/22/2015] [Indexed: 05/30/2023]
Abstract
The amyloid precursor protein/presenilin 1 (APP/PS1) mouse model of Alzheimer's disease (AD) has provided robust neuropathological hallmarks of familial AD-like pattern at early ages, whereas senescence-accelerated mouse prone 8 (SAMP8) has a remarkable early senescence phenotype with pathological similarities to AD. The aim of this study was the investigation and characterization of cognitive and neuropathological AD markers in a novel mouse model that combines the characteristics of the APP/PS1 transgenic mouse model with a senescence-accelerated background of SAMP8 mice. Initially, significant differences were found regarding amyloid plaque formation and cognitive abnormalities. Bearing these facts in mind, we determined a general characterization of the main AD brain molecular markers, such as alterations in amyloid pathway, neuroinflammation, and hyperphosphorylation of tau in these mice along their lifetimes. Results from this analysis revealed that APP/PS1 in SAMP8 background mice showed alterations in the pathways studied in comparison with SAMP8 and APP/PS1, demonstrating that a senescence-accelerated background exacerbated the amyloid pathology and maintained the cognitive dysfunction present in APP/PS1 mice. Changes in tau pathology, including the activity of cyclin-dependent kinase 5 (CDK5) and glycogen synthase kinase 3 β (GSK3β), differs, but not in a parallel manner, with amyloid disturbances.
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Affiliation(s)
- D. Porquet
- />Secció de Farmacologia, Departament Farmacologia i Química Terapèutica, Facultat de Farmàcia, Institut de Biomedicina (IBUB), Universitat de Barcelona (UB), Av. Diagonal 643, 08028 Barcelona, Spain
- />Centros de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - P. Andrés-Benito
- />Secció de Farmacologia, Departament Farmacologia i Química Terapèutica, Facultat de Farmàcia, Institut de Biomedicina (IBUB), Universitat de Barcelona (UB), Av. Diagonal 643, 08028 Barcelona, Spain
| | - C. Griñán-Ferré
- />Secció de Farmacologia, Departament Farmacologia i Química Terapèutica, Facultat de Farmàcia, Institut de Biomedicina (IBUB), Universitat de Barcelona (UB), Av. Diagonal 643, 08028 Barcelona, Spain
- />Centros de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - A. Camins
- />Secció de Farmacologia, Departament Farmacologia i Química Terapèutica, Facultat de Farmàcia, Institut de Biomedicina (IBUB), Universitat de Barcelona (UB), Av. Diagonal 643, 08028 Barcelona, Spain
- />Centros de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - I. Ferrer
- />Institut de Neuropatologia de l’Hospital Universitari de Bellvitge (HUB), Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), Universitat de Barcelona (UB), 08907 Bellvitge, Barcelona Spain
- />Centros de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - A. M. Canudas
- />Secció de Farmacologia, Departament Farmacologia i Química Terapèutica, Facultat de Farmàcia, Institut de Biomedicina (IBUB), Universitat de Barcelona (UB), Av. Diagonal 643, 08028 Barcelona, Spain
- />Centros de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - J. Del Valle
- />Secció de Farmacologia, Departament Farmacologia i Química Terapèutica, Facultat de Farmàcia, Institut de Biomedicina (IBUB), Universitat de Barcelona (UB), Av. Diagonal 643, 08028 Barcelona, Spain
- />Grup de Neuroplasticitat i Regeneració, Institut de Neurociències i Departament de Biologia cellular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Barcelona Spain
- />Centros de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Mercè Pallàs
- />Secció de Farmacologia, Departament Farmacologia i Química Terapèutica, Facultat de Farmàcia, Institut de Biomedicina (IBUB), Universitat de Barcelona (UB), Av. Diagonal 643, 08028 Barcelona, Spain
- />Centros de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
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28
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Marinangeli C, Tasiaux B, Opsomer R, Hage S, Sodero AO, Dewachter I, Octave JN, Smith SO, Constantinescu SN, Kienlen-Campard P. Presenilin transmembrane domain 8 conserved AXXXAXXXG motifs are required for the activity of the γ-secretase complex. J Biol Chem 2015; 290:7169-84. [PMID: 25614624 DOI: 10.1074/jbc.m114.601286] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Understanding the molecular mechanisms controlling the physiological and pathological activity of γ-secretase represents a challenging task in Alzheimer disease research. The assembly and proteolytic activity of this enzyme require the correct interaction of the 19 transmembrane domains (TMDs) present in its four subunits, including presenilin (PS1 or PS2), the γ-secretase catalytic core. GXXXG and GXXXG-like motifs are critical for TMDs interactions as well as for protein folding and assembly. The GXXXG motifs on γ-secretase subunits (e.g. APH-1) or on γ-secretase substrates (e.g. APP) are known to be involved in γ-secretase assembly and in Aβ peptide production, respectively. We identified on PS1 and PS2 TMD8 two highly conserved AXXXAXXXG motifs. The presence of a mutation causing an inherited form of Alzheimer disease (familial Alzheimer disease) in the PS1 motif suggested their involvement in the physiopathological configuration of the γ-secretase complex. In this study, we targeted the role of these motifs on TMD8 of PSs, focusing on their role in PS assembly and catalytic activity. Each motif was mutated, and the impact on complex assembly, activity, and substrate docking was monitored. Different amino acid substitutions on the same motif resulted in opposite effects on γ-secretase activity, without affecting the assembly or significantly impairing the maturation of the complex. Our data suggest that AXXXAXXXG motifs in PS TMD8 are key determinants for the conformation of the mature γ-secretase complex, participating in the switch between the physiological and pathological functional conformations of the γ-secretase.
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Affiliation(s)
| | | | | | - Salim Hage
- the Louvain Drug Research Institute, and
| | | | | | | | - Steven O Smith
- the Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794-5215
| | - Stefan N Constantinescu
- the de Duve Institute and Ludwig Institute for Cancer Research, Université Catholique de Louvain, Brussels 1200, Belgium and
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29
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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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30
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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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31
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Henche AL, van Wolferen M, Ghosh A, Albers SV. Dissection of key determinants of cleavage activity in signal peptidase III (SPaseIII) PibD. Extremophiles 2014; 18:905-13. [PMID: 25102813 DOI: 10.1007/s00792-014-0675-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 07/06/2014] [Indexed: 10/24/2022]
Abstract
In Archaea, type IV prepilins and prearchaellins are processed by designated signal peptidase III (SPaseIII) prior to their incorporation into pili and the archaellum, respectively. These peptidases belong to the family of integral membrane aspartic acid proteases that contain two essential aspartate residues of which the second aspartate is located in a conserved GxGD motif. To this group also bacterial type IV prepilin peptidases, Alzheimer disease-related secretases, signal peptide peptidases and signal peptide peptidase-like proteases in humans belong. Here we have performed detailed in vivo analyses to understand the cleavage activity of PibD, SPaseIII from the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius. Using an already established in vivo heterologous system cleavage assay, we could successfully identify the key amino acid residues essential for catalysis of PibD. Furthermore, in trans complementation of a pibD S. acidocaldarius deletion mutant with PibD variants having substituted key amino acids has consolidated our observations of the importance of these residues in catalysis. Based on our data, we propose to re-define class III peptidases/type IV prepilin/prearchaellin peptidases as GxHyD group (rather than GxGD) of proteases [Hy-hydrophobic amino acid].
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Affiliation(s)
- Anna-Lena Henche
- Molecular Biology of Archaea, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043, Marburg, Germany
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32
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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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33
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Evidence of a novel mechanism for partial γ-secretase inhibition induced paradoxical increase in secreted amyloid β protein. PLoS One 2014; 9:e91531. [PMID: 24658363 PMCID: PMC3962361 DOI: 10.1371/journal.pone.0091531] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 02/12/2014] [Indexed: 02/02/2023] Open
Abstract
BACE1 (β-secretase) and α-secretase cleave the Alzheimer's amyloid β protein (Aβ) precursor (APP) to C-terminal fragments of 99 aa (CTFβ) and 83 aa (CTFα), respectively, which are further cleaved by γ-secretase to eventually secrete Aβ and Aα (a.k.a. P3) that terminate predominantly at residues 40 and 42. A number of γ-secretase inhibitors (GSIs), such as N-[N-(3,5-Difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester (DAPT), have been developed with the goal of reducing Aβ to treat Alzheimer's disease (AD). Although most studies show that DAPT inhibits Aβ in a dose-dependent manner several studies have also detected a biphasic effect with an unexpected increase at low doses of DAPT in cell cultures, animal models and clinical trials. In this article, we confirm the increase in Aβ40 and Aβ42 in SH-SY5Y human neuroblastoma cells treated with low doses of DAPT and identify one of the mechanisms for this paradox. We studied the pathway by first demonstrating that stimulation of Aβ, a product of γ-secretase, was accompanied by a parallel increase of its substrate CTFβ, thereby demonstrating that the inhibitor was not anomalously stimulating enzyme activity at low levels. Secondly, we have demonstrated that inhibition of an Aβ degrading activity, endothelin converting enzyme (ECE), yielded more Aβ, but abolished the DAPT-induced stimulation. Finally, we have demonstrated that Aα, which is generated in the secretory pathway before endocytosis, is not subject to the DAPT-mediated stimulation. We therefore conclude that impairment of γ-secretase can paradoxically increase Aβ by transiently skirting Aβ degradation in the endosome. This study adds to the growing body of literature suggesting that preserving γ-secretase activity, rather than inhibiting it, is important for prevention of neurodegeneration.
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34
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Jung JI, Ran Y, Cruz PE, Rosario AM, Ladd TB, Kukar TL, Koo EH, Felsenstein KM, Golde TE. Complex relationships between substrate sequence and sensitivity to alterations in γ-secretase processivity induced by γ-secretase modulators. Biochemistry 2014; 53:1947-57. [PMID: 24620716 PMCID: PMC3985764 DOI: 10.1021/bi401521t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
γ-Secretase
catalyzes the final cleavage of the amyloid precursor
protein (APP), resulting in the production of amyloid-β (Aβ)
peptides with different carboxyl termini. Presenilin (PSEN) and amyloid precursor protein (APP) mutations
linked to early onset familial Alzheimer’s disease modify the
profile of Aβ isoforms generated, by altering both the initial
γ-secretase cleavage site and subsequent processivity in a manner
that leads to increased levels of the more amyloidogenic Aβ42
and in some circumstances Aβ43. Compounds termed γ-secretase
modulators (GSMs) and inverse GSMs (iGSMs) can decrease and increase
levels of Aβ42, respectively. As GSMs lower the level of production
of pathogenic forms of long Aβ isoforms, they are of great interest
as potential Alzheimer’s disease therapeutics. The factors
that regulate GSM modulation are not fully understood; however, there
is a growing body of evidence that supports the hypothesis that GSM
activity is influenced by the amino acid sequence of the γ-secretase
substrate. We have evaluated whether mutations near the luminal border
of the transmembrane domain (TMD) of APP alter the ability of both
acidic, nonsteroidal anti-inflammatory drug-derived carboxylate and
nonacidic,
phenylimidazole-derived classes of GSMs and iGSMs to modulate γ-secretase
cleavage. Our data show that point mutations can dramatically reduce
the sensitivity to modulation of cleavage by GSMs but have weaker
effects on iGSM activity. These studies support the concept that the
effect of GSMs may be substrate selective; for APP, it is dependent
on the amino acid sequence of the substrate near the junction of the
extracellular domain and luminal segment of the TMD.
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Affiliation(s)
- Joo In Jung
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, and McKnight Brain Institute, College of Medicine, University of Florida , Gainesville, Florida 32603, United States
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35
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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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Urban S. Mechanisms and cellular functions of intramembrane proteases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2797-800. [PMID: 23831604 DOI: 10.1016/j.bbamem.2013.07.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The turn of the millennium coincided with the branding of a fundamentally different class of enzyme - proteases that reside immersed inside the membrane. This new field was the convergence of completely separate lines of research focused on cholesterol homeostasis, Alzheimer's disease, and developmental genetics. None intended their ultimate path, but soon became a richly-integrated fabric for an entirely new field: regulated intramembrane proteolysis. Our aim in this Special Issue is to focus on the ancient and nearly ubiquitous enzymes that catalyze this unexpected yet important reaction. The pace of progress has been dramatic, resulting in a rapidly-expanding universe of known cellular functions, and a paradigm shift in the biochemical understanding of these once heretical enzymes. More recently, the first therapeutic successes have been attained by targeting an intramembrane protease. We consider these advances and identify oncoming opportunities in four parts: growing spectra of cellular roles, insights into biochemical mechanisms, therapeutic strategies, and newly-emerging topics. Recent studies also expose challenges for the future, including non-linear relationships between substrate identification and physiological functions, and the need for potent and specific, not broad-class, inhibitors.
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Affiliation(s)
- Siniša Urban
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA.
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