1
|
Trambauer J, Sarmiento RMR, Garringer HJ, Salbaum K, Pedro LD, Crusius D, Vidal R, Ghetti B, Paquet D, Baumann K, Lindemann L, Steiner H. γ-Secretase modulator resistance of an aggressive Alzheimer-causing presenilin mutant can be overcome in the heterozygous patient state by a set of advanced compounds. Alzheimers Res Ther 2025; 17:49. [PMID: 39972463 PMCID: PMC11837686 DOI: 10.1186/s13195-025-01680-3] [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: 12/11/2024] [Accepted: 01/20/2025] [Indexed: 02/21/2025]
Abstract
BACKGROUND Amyloid-β peptide (Aβ) species of 42 or 43 amino acids in length (Aβ42/43) trigger Alzheimer´s disease (AD) and are produced in abnormal amounts by mutants of the γ-secretase subunit presenilin-1 (PS1), which represent the primary cause of familial AD (FAD). Lowering these peptides by γ-secretase modulators (GSMs) is increasingly considered a safe strategy to treat AD since these compounds do not affect the overall cleavage of γ-secretase substrates. GSMs were shown to modulate not only wild-type (WT) γ-secretase but also FAD mutants, expanding their potential use also to the familial form of the disease. Unlike most other FAD mutants, the very aggressive PS1 L166P mutant is largely resistant to GSMs. However, these data were mostly obtained from overexpression models, which mimic more the less relevant homozygous state rather than the heterozygous patient situation. METHODS Mouse embryonic fibroblast and induced pluripotent stem cell-derived neuronal PS1 L166P knock-in (KI) cell models were treated with various GSMs and Aβ responses were assessed by immunoassays and/or gel-based analysis. RESULTS We identified GSMs that lower Aβ42 and/or Aβ43 when PS1 L166P is heterozygous, as it is the case in affected patients, and could reduce the amount of pathogenic Aβ species towards WT levels. RO7019009 was the most potent of these compounds, reducing both pathogenic species and concomitantly increasing the short Aβ37 and Aβ38, of which the latter has been associated with delayed AD progression. Another effective compound, the structurally novel indole-type GSM RO5254601 specifically acts on the Aβ42 product line leading to a selective increase of the beneficial Aβ38. Interestingly, we further found that this class of GSMs can bind not only one, but both presenilin fragments suggesting that it targets γ-secretase at an unusual binding site. CONCLUSION Our data show that even highly refractory presenilin FAD mutants are in principle tractable with GSMs extending the possibilities for potential clinical studies in FAD with suitable GSM molecules.
Collapse
Affiliation(s)
- Johannes Trambauer
- Division of Metabolic Biochemistry, Faculty of Medicine, Biomedical Center (BMC), LMU Munich, Feodor-Lynen-Str. 17, Munich, 81377, Germany
- German Center for Neurodegenerative Diseases (DZNE), Munich, 81377, Germany
| | - Rosa Maria Rodriguez Sarmiento
- Pharma Research and Early Development, F. Hoffmann-La Roche AG, Therapeutic Modalities, Small Molecule Research, Roche Innovation Center Basel, Basel, 4070, Switzerland
| | - Holly J Garringer
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Katja Salbaum
- Institute for Stroke and Dementia Research, University Hospital, LMU Munich, Munich, 81377, Germany
| | - Liliana D Pedro
- German Center for Neurodegenerative Diseases (DZNE), Munich, 81377, Germany
- Institute for Stroke and Dementia Research, University Hospital, LMU Munich, Munich, 81377, Germany
| | - Dennis Crusius
- Institute for Stroke and Dementia Research, University Hospital, LMU Munich, Munich, 81377, Germany
| | - Ruben Vidal
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Bernardino Ghetti
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Dominik Paquet
- Institute for Stroke and Dementia Research, University Hospital, LMU Munich, Munich, 81377, Germany
- Munich Cluster of Systems Neurology (SyNergy), Munich, 81377, Germany
| | - Karlheinz Baumann
- Pharma Research and Early Development, F. Hoffmann-La Roche AG, Neuroscience and Rare Diseases Translational Area, Neuroscience Discovery, Roche Innovation Center Basel, Basel, 4070, Switzerland
| | - Lothar Lindemann
- Pharma Research and Early Development, F. Hoffmann-La Roche AG, Neuroscience and Rare Diseases Translational Area, Neuroscience Discovery, Roche Innovation Center Basel, Basel, 4070, Switzerland
| | - Harald Steiner
- Division of Metabolic Biochemistry, Faculty of Medicine, Biomedical Center (BMC), LMU Munich, Feodor-Lynen-Str. 17, Munich, 81377, Germany.
- German Center for Neurodegenerative Diseases (DZNE), Munich, 81377, Germany.
| |
Collapse
|
2
|
Chen SY, Koch M, Chávez-Gutiérrez L, Zacharias M. How Modulator Binding at the Amyloidβ-γ-Secretase Interface Enhances Substrate Binding and Attenuates Membrane Distortion. J Med Chem 2023; 66:16772-16782. [PMID: 38059872 DOI: 10.1021/acs.jmedchem.3c01480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
Inhibition of γ-secretase, an intramembrane protease, to reduce secretion of Amyloid-β (Aβ) peptides has been considered for treating Alzheimer's disease. However, γ-secretase inhibitors suffer from severe side effects. As an alternative, γ-secretase modulators (GSM) reduce the generation of toxic peptides by enhancing the cleavage processivity without diminishing the enzyme activity. Starting from a known γ-secretase structure without substrate but in complex with an E2012 GSM, we generated a structural model that included a bound Aβ43 peptide and studied interactions among enzyme, substrate, GSM, and lipids. Our result suggests that E2012 binding at the enzyme-substrate-membrane interface attenuates the membrane distortion by shielding the substrate-membrane interaction. The model predicts that the E2012 modulation is charge-dependent and explains the preserved hydrogen acceptor and the aromatic ring observed in many imidazole-based GSM. Predicted effects of γ-secretase mutations on E2012 modulation were confirmed experimentally. We anticipate that the study will facilitate the future development of effective GSMs.
Collapse
Affiliation(s)
- Shu-Yu Chen
- Center for Functional Protein Assemblies, Garching 85748, Germany
| | - Matthias Koch
- VIB/KU Leuven, VIB-KU Leuven Center for Brain & Disease Research, Leuven 3000, Belgium
| | | | - Martin Zacharias
- Center for Functional Protein Assemblies, Garching 85748, Germany
| |
Collapse
|
3
|
Koch M, Enzlein T, Chen S, Petit D, Lismont S, Zacharias M, Hopf C, Chávez‐Gutiérrez L. APP substrate ectodomain defines amyloid-β peptide length by restraining γ-secretase processivity and facilitating product release. EMBO J 2023; 42:e114372. [PMID: 37853914 PMCID: PMC10690472 DOI: 10.15252/embj.2023114372] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 09/19/2023] [Accepted: 09/25/2023] [Indexed: 10/20/2023] Open
Abstract
Sequential proteolysis of the amyloid precursor protein (APP) by γ-secretases generates amyloid-β (Aβ) peptides and defines the proportion of short-to-long Aβ peptides, which is tightly connected to Alzheimer's disease (AD) pathogenesis. Here, we study the mechanism that controls substrate processing by γ-secretases and Aβ peptide length. We found that polar interactions established by the APPC99 ectodomain (ECD), involving but not limited to its juxtamembrane region, restrain both the extent and degree of γ-secretases processive cleavage by destabilizing enzyme-substrate interactions. We show that increasing hydrophobicity, via mutation or ligand binding, at APPC99 -ECD attenuates substrate-driven product release and rescues the effects of Alzheimer's disease-associated pathogenic γ-secretase and APP variants on Aβ length. In addition, our study reveals that APPC99 -ECD facilitates the paradoxical production of longer Aβs caused by some γ-secretase inhibitors, which act as high-affinity competitors of the substrate. These findings assign a pivotal role to the substrate ECD in the sequential proteolysis by γ-secretases and suggest it as a sweet spot for the potential design of APP-targeting compounds selectively promoting its processing by these enzymes.
Collapse
Affiliation(s)
- Matthias Koch
- VIB/KU Leuven, VIB‐KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
| | - Thomas Enzlein
- VIB/KU Leuven, VIB‐KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- Center for Mass Spectrometry and Optical Spectroscopy (CeMOS)Mannheim University of Applied SciencesMannheimGermany
| | - Shu‐Yu Chen
- Physics Department and Center of Functional Protein AssembliesTechnical University of MunichGarchingGermany
| | - Dieter Petit
- VIB/KU Leuven, VIB‐KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
| | - Sam Lismont
- VIB/KU Leuven, VIB‐KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
| | - Martin Zacharias
- Physics Department and Center of Functional Protein AssembliesTechnical University of MunichGarchingGermany
| | - Carsten Hopf
- Center for Mass Spectrometry and Optical Spectroscopy (CeMOS)Mannheim University of Applied SciencesMannheimGermany
- Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty MannheimHeidelberg UniversityMannheimGermany
- Medical FacultyHeidelberg UniversityHeidelbergGermany
| | | |
Collapse
|
4
|
Chen SY, Feilen LP, Chávez-Gutiérrez L, Steiner H, Zacharias M. Enzyme-substrate hybrid β-sheet controls geometry and water access to the γ-secretase active site. Commun Biol 2023; 6:670. [PMID: 37355752 PMCID: PMC10290658 DOI: 10.1038/s42003-023-05039-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 06/12/2023] [Indexed: 06/26/2023] Open
Abstract
γ-Secretase is an aspartyl intramembrane protease that cleaves the amyloid precursor protein (APP) involved in Alzheimer's disease pathology and other transmembrane proteins. Substrate-bound structures reveal a stable hybrid β-sheet immediately following the substrate scissile bond consisting of β1 and β2 from the enzyme and β3 from the substrate. Molecular dynamics simulations and enhanced sampling simulations demonstrate that the hybrid β-sheet stability is strongly correlated with the formation of a stable cleavage-compatible active geometry and it also controls water access to the active site. The hybrid β-sheet is only stable for substrates with 3 or more C-terminal residues beyond the scissile bond. The simulation model allowed us to predict the effect of Pro and Phe mutations that weaken the formation of the hybrid β-sheet which were confirmed by experimental testing. Our study provides a direct explanation why γ-secretase preferentially cleaves APP in steps of 3 residues and how the hybrid β-sheet facilitates γ-secretase proteolysis.
Collapse
Affiliation(s)
- Shu-Yu Chen
- Center of Functional Protein Assemblies, Technical University of Munich, Garching, Germany
| | - Lukas P Feilen
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Lucía Chávez-Gutiérrez
- VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
- Department of Neurosciences, Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven, Leuven, Belgium
| | - Harald Steiner
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Biomedical Center (BMC), Division of Metabolic Biochemistry, Faculty of Medicine, LMU Munich, Germany
| | - Martin Zacharias
- Center of Functional Protein Assemblies, Technical University of Munich, Garching, Germany.
| |
Collapse
|
5
|
Li X, Ospitalieri S, Robberechts T, Hofmann L, Schmid C, Rijal Upadhaya A, Koper MJ, von Arnim CAF, Kumar S, Willem M, Gnoth K, Ramakers M, Schymkowitz J, Rousseau F, Walter J, Ronisz A, Balakrishnan K, Thal DR. Seeding, maturation and propagation of amyloid β-peptide aggregates in Alzheimer’s disease. Brain 2022; 145:3558-3570. [PMID: 36270003 DOI: 10.1093/brain/awac202] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 05/18/2022] [Accepted: 05/20/2022] [Indexed: 11/13/2022] Open
Abstract
Abstract
Alzheimer’s disease is neuropathologically characterized by the deposition of the amyloid β-peptide (Aβ) as amyloid plaques. Aβ plaque pathology starts in the neocortex before it propagates into further brain regions. Moreover, Aβ aggregates undergo maturation indicated by the occurrence of post-translational modifications. Here, we show that propagation of Aβ plaques is led by presumably non-modified Aβ followed by Aβ aggregate maturation. This sequence was seen neuropathologically in human brains and in amyloid precursor protein transgenic mice receiving intracerebral injections of human brain homogenates from cases varying in Aβ phase, Aβ load and Aβ maturation stage. The speed of propagation after seeding in mice was best related to the Aβ phase of the donor, the progression speed of maturation to the stage of Aβ aggregate maturation. Thus, different forms of Aβ can trigger propagation/maturation of Aβ aggregates, which may explain the lack of success when therapeutically targeting only specific forms of Aβ.
Collapse
Affiliation(s)
- Xiaohang Li
- Department of Imaging and Pathology, Laboratory of Neuropathology, Leuven Brain Institute, KU-Leuven , Leuven , Belgium
| | - Simona Ospitalieri
- Department of Imaging and Pathology, Laboratory of Neuropathology, Leuven Brain Institute, KU-Leuven , Leuven , Belgium
| | - Tessa Robberechts
- Department of Imaging and Pathology, Laboratory of Neuropathology, Leuven Brain Institute, KU-Leuven , Leuven , Belgium
| | - Linda Hofmann
- Institute of Pathology, Laboratory of Neuropathology, Ulm University , Ulm , Germany
| | - Christina Schmid
- Institute of Pathology, Laboratory of Neuropathology, Ulm University , Ulm , Germany
| | - Ajeet Rijal Upadhaya
- Institute of Pathology, Laboratory of Neuropathology, Ulm University , Ulm , Germany
| | - Marta J Koper
- Department of Imaging and Pathology, Laboratory of Neuropathology, Leuven Brain Institute, KU-Leuven , Leuven , Belgium
- Laboratory for the Research of Neurodegenerative Diseases, Department of Neurosciences, KU-Leuven (University of Leuven), Leuven Brain Institute , Leuven , Belgium
- Center for Brain and Disease Research, VIB , Leuven , Belgium
| | - Christine A F von Arnim
- Department of Neurology, Ulm University , Ulm , Germany
- Division of Geriatrics, University Medical Center Göttingen , Göttingen , Germany
| | - Sathish Kumar
- Department of Neurology, University of Bonn , Bonn , Germany
| | - Michael Willem
- Chair of Metabolic Biochemistry, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-University Munich , Munich , Germany
| | - Kathrin Gnoth
- Department of Drug Design and Target Validation, Fraunhofer Institute for Cell Therapy and Immunology , Halle , Germany
| | - Meine Ramakers
- Center for Brain and Disease Research, VIB , Leuven , Belgium
- Switch Laboratory, Department of Cellular and Molecular Medicine, KU-Leuven , Leuven , Belgium
| | - Joost Schymkowitz
- Center for Brain and Disease Research, VIB , Leuven , Belgium
- Switch Laboratory, Department of Cellular and Molecular Medicine, KU-Leuven , Leuven , Belgium
| | - Frederic Rousseau
- Center for Brain and Disease Research, VIB , Leuven , Belgium
- Switch Laboratory, Department of Cellular and Molecular Medicine, KU-Leuven , Leuven , Belgium
| | - Jochen Walter
- Department of Neurology, University of Bonn , Bonn , Germany
| | - Alicja Ronisz
- Department of Imaging and Pathology, Laboratory of Neuropathology, Leuven Brain Institute, KU-Leuven , Leuven , Belgium
| | - Karthikeyan Balakrishnan
- Institute of Pathology, Laboratory of Neuropathology, Ulm University , Ulm , Germany
- Department of Gene Therapy, Ulm University , Ulm , Germany
| | - Dietmar Rudolf Thal
- Department of Imaging and Pathology, Laboratory of Neuropathology, Leuven Brain Institute, KU-Leuven , Leuven , Belgium
- Institute of Pathology, Laboratory of Neuropathology, Ulm University , Ulm , Germany
- Department of Pathology, UZ-Leuven , Leuven , Belgium
| |
Collapse
|
6
|
Chen SY, Zacharias M. An internal docking site stabilizes substrate binding to γ-secretase: Analysis by molecular dynamics simulations. Biophys J 2022; 121:2330-2344. [PMID: 35598043 PMCID: PMC9279352 DOI: 10.1016/j.bpj.2022.05.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/26/2022] [Accepted: 05/17/2022] [Indexed: 11/02/2022] Open
Abstract
Amyloid precursor protein (APP) is cleaved and processed sequentially by γ-secretase yielding amyloid β (Aβ) peptides of different lengths. Longer Aβ peptides are associated with the formation of neurotoxic plaques related to Alzheimer's disease. Based on the APP substrate-bound structure of γ-secretase, we investigated the enzyme-substrate interaction using molecular dynamics simulations and generated model structures that represent the sequentially cleaved intermediates during the processing reaction. The simulations indicated an internal docking site providing strong enzyme-substrate packing interaction. In the enzyme-substrate complex, it is located close to the region where the helical conformation of the substrate is interrupted and continues toward the active site in an extended conformation. The internal docking site consists of two non-polar pockets that are preferentially filled by large hydrophobic or aromatic substrate side chains to stabilize binding. Placement of smaller residues such as glycine can trigger a shift in the cleavage pattern during the simulations or results in destabilization of substrate binding. The reduced packing by smaller residues also influences the hydration of the active site and the formation of a catalytically active state. The simulations on processed substrate intermediates and a substrate G33I mutation offer an explanation of the experimentally observed relative increase of short Aβ fragment production for this mutation. In addition, studies on a substrate K28A mutation indicate that the internal docking site opposes the tendency of substrate dissociation due to a hydrophobic mismatch at the membrane boundary caused by K28 during processing and substrate movement toward the enzyme active site. The proposed internal docking site could also be useful for the specific design of new γ-secretase modulators.
Collapse
Affiliation(s)
- Shu-Yu Chen
- Physics Department and Center of Functional Protein Assemblies, Technical University of Munich, 85748 Garching, Germany
| | - Martin Zacharias
- Physics Department and Center of Functional Protein Assemblies, Technical University of Munich, 85748 Garching, Germany.
| |
Collapse
|
7
|
Silber M, Hitzenberger M, Zacharias M, Muhle-Goll C. Altered Hinge Conformations in APP Transmembrane Helix Mutants May Affect Enzyme-Substrate Interactions of γ-Secretase. ACS Chem Neurosci 2020; 11:4426-4433. [PMID: 33232115 DOI: 10.1021/acschemneuro.0c00640] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cleavage of substrates by γ-secretase is an inherently slow process where substrate-enzyme affinities cannot be broken down into specific sequence requirements in contrast to soluble proteases. Nevertheless, despite its apparent sequence tolerance single point mutations in amyloid precursor protein can severely affect cleavage efficiencies and change product line preferences. We have determined by NMR spectroscopy the structures of the transmembrane domain of amyloid precursor protein in TFE/water and compared it to that of four mutants: two FAD mutants, V44M and I45T, and the two diglycine hinge mutants, G38L and G38P. In accordance with previous publications, the transmembrane domain is composed of two helical segments connected by the diglycine hinge. Mutations alter kink angles and structural flexibility. Furthermore, to our surprise, we observe different, but specific mutual orientations of N- and C-terminal helical segments in the four mutants compared to the wildtype. We speculate that the observed orientations for G38L, G38P, V44M, and I45T lead to unfavorable interactions with γ-secretase exosites during substrate movement to the enzyme's active site in presenilin and/or for the accommodation into the substrate-binding cavity of presenilin.
Collapse
Affiliation(s)
- Mara Silber
- Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Manuel Hitzenberger
- Physics Department T38, Technical University of Munich, James-Frank-Str. 1, 85748 Garching, Germany
| | - Martin Zacharias
- Physics Department T38, Technical University of Munich, James-Frank-Str. 1, 85748 Garching, Germany
| | - Claudia Muhle-Goll
- Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe, Germany
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| |
Collapse
|
8
|
Substrate recruitment by γ-secretase. Semin Cell Dev Biol 2020; 105:54-63. [DOI: 10.1016/j.semcdb.2020.03.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 03/18/2020] [Accepted: 03/20/2020] [Indexed: 12/27/2022]
|
9
|
Schlepckow K, Monroe KM, Kleinberger G, Cantuti‐Castelvetri L, Parhizkar S, Xia D, Willem M, Werner G, Pettkus N, Brunner B, Sülzen A, Nuscher B, Hampel H, Xiang X, Feederle R, Tahirovic S, Park JI, Prorok R, Mahon C, Liang C, Shi J, Kim DJ, Sabelström H, Huang F, Di Paolo G, Simons M, Lewcock JW, Haass C. Enhancing protective microglial activities with a dual function TREM2 antibody to the stalk region. EMBO Mol Med 2020; 12:e11227. [PMID: 32154671 PMCID: PMC7136959 DOI: 10.15252/emmm.201911227] [Citation(s) in RCA: 187] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 02/12/2020] [Accepted: 02/17/2020] [Indexed: 01/07/2023] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is essential for the transition of homeostatic microglia to a disease-associated microglial state. To enhance TREM2 activity, we sought to selectively increase the full-length protein on the cell surface via reducing its proteolytic shedding by A Disintegrin And Metalloproteinase (i.e., α-secretase) 10/17. We screened a panel of monoclonal antibodies against TREM2, with the aim to selectively compete for α-secretase-mediated shedding. Monoclonal antibody 4D9, which has a stalk region epitope close to the cleavage site, demonstrated dual mechanisms of action by stabilizing TREM2 on the cell surface and reducing its shedding, and concomitantly activating phospho-SYK signaling. 4D9 stimulated survival of macrophages and increased microglial uptake of myelin debris and amyloid β-peptide in vitro. In vivo target engagement was demonstrated in cerebrospinal fluid, where nearly all soluble TREM2 was 4D9-bound. Moreover, in a mouse model for Alzheimer's disease-related pathology, 4D9 reduced amyloidogenesis, enhanced microglial TREM2 expression, and reduced a homeostatic marker, suggesting a protective function by driving microglia toward a disease-associated state.
Collapse
Affiliation(s)
- Kai Schlepckow
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
| | | | - Gernot Kleinberger
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
- Present address:
ISAR Bioscience GmbHPlaneggGermany
| | | | - Samira Parhizkar
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Dan Xia
- Denali Therapeutics Inc.South San FranciscoCAUSA
| | - Michael Willem
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Georg Werner
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Nadine Pettkus
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Bettina Brunner
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
| | - Alice Sülzen
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
| | - Brigitte Nuscher
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Heike Hampel
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Xianyuan Xiang
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
- Graduate School of Systemic NeuroscienceLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Regina Feederle
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
- Munich Cluster for Systems Neurology (SyNergy)MunichGermany
- Helmholtz Center MunichGerman Research Center for Environmental HealthInstitute for Diabetes and ObesityCore Facility Monoclonal Antibody DevelopmentMunichGermany
| | - Sabina Tahirovic
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
| | | | | | - Cathal Mahon
- Denali Therapeutics Inc.South San FranciscoCAUSA
| | | | - Ju Shi
- Denali Therapeutics Inc.South San FranciscoCAUSA
- Present address:
Jazz PharmaceuticalsPalo AltoCAUSA
| | - Do Jin Kim
- Denali Therapeutics Inc.South San FranciscoCAUSA
| | | | - Fen Huang
- Denali Therapeutics Inc.South San FranciscoCAUSA
| | | | - Mikael Simons
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
- Munich Cluster for Systems Neurology (SyNergy)MunichGermany
- Institute of Neuronal Cell Biology (TUM‐NZB)MunichGermany
| | | | - Christian Haass
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
- Munich Cluster for Systems Neurology (SyNergy)MunichGermany
| |
Collapse
|
10
|
Trambauer J, Fukumori A, Steiner H. Pathogenic Aβ generation in familial Alzheimer’s disease: novel mechanistic insights and therapeutic implications. Curr Opin Neurobiol 2020; 61:73-81. [DOI: 10.1016/j.conb.2020.01.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 01/16/2020] [Accepted: 01/23/2020] [Indexed: 01/06/2023]
|
11
|
Trambauer J, Rodríguez Sarmiento RM, Fukumori A, Feederle R, Baumann K, Steiner H. Aβ43-producing PS1 FAD mutants cause altered substrate interactions and respond to γ-secretase modulation. EMBO Rep 2020; 21:e47996. [PMID: 31762188 PMCID: PMC6945062 DOI: 10.15252/embr.201947996] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 12/22/2022] Open
Abstract
Abnormal generation of neurotoxic amyloid-β peptide (Aβ) 42/43 species due to mutations in the catalytic presenilin 1 (PS1) subunit of γ-secretase is the major cause of familial Alzheimer's disease (FAD). Deeper mechanistic insight on the generation of Aβ43 is still lacking, and it is unclear whether γ-secretase modulators (GSMs) can reduce the levels of this Aβ species. By comparing several types of Aβ43-generating FAD mutants, we observe that very high levels of Aβ43 are often produced when presenilin function is severely impaired. Altered interactions of C99, the precursor of Aβ, are found for all mutants and are independent of their particular effect on Aβ production. Furthermore, unlike previously described GSMs, the novel compound RO7019009 can effectively lower Aβ43 production of all mutants. Finally, substrate-binding competition experiments suggest that RO7019009 acts mechanistically after initial C99 binding. We conclude that altered C99 interactions are a common feature of diverse types of PS1 FAD mutants and that also patients with Aβ43-generating FAD mutations could in principle be treated by GSMs.
Collapse
Affiliation(s)
- Johannes Trambauer
- Biomedical Center (BMC), Metabolic BiochemistryLudwig‐Maximilians‐UniversityMunichGermany
| | | | - Akio Fukumori
- Department of Aging NeurobiologyNational Center for Geriatrics and GerontologyObuJapan
- Department of Mental Health PromotionOsaka University Graduate School of MedicineToyonakaJapan
| | - Regina Feederle
- Institute for Diabetes and Obesity, Monoclonal Antibody Core Facility, Helmholtz Center MunichGerman Research Center for Environmental HealthNeuherbergGermany
- German Center for Neurodegenerative Diseases (DZNE)MunichGermany
| | - Karlheinz Baumann
- Roche Pharma Research and Early DevelopmentRoche Innovation Center Basel, F. Hoffmann‐La Roche Ltd.BaselSwitzerland
| | - Harald Steiner
- Biomedical Center (BMC), Metabolic BiochemistryLudwig‐Maximilians‐UniversityMunichGermany
- German Center for Neurodegenerative Diseases (DZNE)MunichGermany
| |
Collapse
|
12
|
Mahmoud WR, Nissan YM, Elsawah MM, Refaey RH, Ragab MF, Amin KM. Neurobehavioral investigation and acetylcholinesterase inhibitory activity study for some new coumarin derivatives. Eur J Med Chem 2019; 182:111651. [DOI: 10.1016/j.ejmech.2019.111651] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/19/2019] [Accepted: 08/27/2019] [Indexed: 12/23/2022]
|
13
|
Petit D, Hitzenberger M, Lismont S, Zoltowska KM, Ryan NS, Mercken M, Bischoff F, Zacharias M, Chávez-Gutiérrez L. Extracellular interface between APP and Nicastrin regulates Aβ length and response to γ-secretase modulators. EMBO J 2019; 38:e101494. [PMID: 31109937 PMCID: PMC6576158 DOI: 10.15252/embj.2019101494] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 04/02/2019] [Accepted: 04/11/2019] [Indexed: 12/20/2022] Open
Abstract
γ-Secretase complexes (GSECs) are multimeric membrane proteases involved in a variety of physiological processes and linked to Alzheimer's disease (AD). Presenilin (PSEN, catalytic subunit), Nicastrin (NCT), Presenilin Enhancer 2 (PEN-2), and Anterior Pharynx Defective 1 (APH1) are the essential subunits of GSECs. Mutations in PSEN and the Amyloid Precursor Protein (APP) cause early-onset AD GSECs successively cut APP to generate amyloid-β (Aβ) peptides of various lengths. AD-causing mutations destabilize GSEC-APP/Aβn interactions and thus enhance the production of longer Aβs, which elicit neurotoxic events underlying pathogenesis. Here, we investigated the molecular strategies that anchor GSEC and APP/Aβn during the sequential proteolysis. Our studies reveal that a direct interaction between NCT ectodomain and APPC99 influences the stability of GSEC-Aβn assemblies and thereby modulates Aβ length. The data suggest a potential link between single-nucleotide variants in NCSTN and AD risk. Furthermore, our work indicates that an extracellular interface between the protease (NCT, PSEN) and the substrate (APP) represents the target for compounds (GSMs) modulating Aβ length. Our findings may guide future rationale-based drug discovery efforts.
Collapse
Affiliation(s)
- Dieter Petit
- VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
- Department of Neurosciences, Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven, Leuven, Belgium
| | - Manuel Hitzenberger
- Physics Department, Theoretical Biophysics (T38), Technical University of Munich, München, Germany
| | - Sam Lismont
- VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
- Department of Neurosciences, Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven, Leuven, Belgium
| | - Katarzyna Marta Zoltowska
- VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
- Department of Neurosciences, Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven, Leuven, Belgium
| | - Natalie S Ryan
- Dementia Research Centre, Department of Neurodegenerative Disease UCL Queen Square Institute of Neurology, London, UK
| | - Marc Mercken
- Janssen Research & Development, Division of Janssen Pharmaceutica NV, Beerse, Belgium
- Janssen Research & Development, Neuroscience biology Turnhoutseweg, Beerse, Belgium
| | - François Bischoff
- Janssen Research & Development, Division of Janssen Pharmaceutica NV, Beerse, Belgium
| | - Martin Zacharias
- Physics Department, Theoretical Biophysics (T38), Technical University of Munich, München, Germany
| | - Lucía Chávez-Gutiérrez
- VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
- Department of Neurosciences, Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven, Leuven, Belgium
| |
Collapse
|
14
|
Katzmarski N, Ziegler-Waldkirch S, Scheffler N, Witt C, Abou-Ajram C, Nuscher B, Prinz M, Haass C, Meyer-Luehmann M. Aβ oligomers trigger and accelerate Aβ seeding. Brain Pathol 2019; 30:36-45. [PMID: 31099449 PMCID: PMC6916291 DOI: 10.1111/bpa.12734] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 05/06/2019] [Indexed: 12/12/2022] Open
Abstract
Aggregation of amyloid‐β (Aβ) that leads to the formation of plaques in Alzheimer's disease (AD) occurs through the stepwise formation of oligomers and fibrils. An earlier onset of aggregation is obtained upon intracerebral injection of Aβ‐containing brain homogenate into human APP transgenic mice that follows a prion‐like seeding mechanism. Immunoprecipitation of these brain extracts with anti‐Aβ oligomer antibodies or passive immunization of the recipient animals abrogated the observed seeding activity, although induced Aβ deposition was still evident. Here, we establish that, together with Aβ monomers, Aβ oligomers trigger the initial phase of Aβ seeding and that the depletion of oligomeric Aβ delays the aggregation process, leading to a transient reduction of seed‐induced Aβ deposits. This work extends the current knowledge about the role of Aβ oligomers beyond its cytotoxic nature by pointing to a role in the initiation of Aβ aggregation in vivo. We conclude that Aβ oligomers are important for the early initiation phase of the seeding process.
Collapse
Affiliation(s)
- Natalie Katzmarski
- Department of Neurology, Medical Center - University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Stephanie Ziegler-Waldkirch
- Department of Neurology, Medical Center - University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Nina Scheffler
- Department of Neurology, Medical Center - University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Christian Witt
- Department of Neurology, Medical Center - University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Claudia Abou-Ajram
- Biomedical Center (BMC), Ludwig-Maximilians-University Munich, Munich, Germany
| | - Brigitte Nuscher
- Biomedical Center (BMC), Ludwig-Maximilians-University Munich, Munich, Germany
| | - Marco Prinz
- Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Insitute of Neuropathology, Medical Center - University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Christian Haass
- Biomedical Center (BMC), Ludwig-Maximilians-University Munich, Munich, Germany.,German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Melanie Meyer-Luehmann
- Department of Neurology, Medical Center - University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| |
Collapse
|
15
|
Götz A, Högel P, Silber M, Chaitoglou I, Luy B, Muhle-Goll C, Scharnagl C, Langosch D. Increased H-Bond Stability Relates to Altered ε-Cleavage Efficiency and Aβ Levels in the I45T Familial Alzheimer's Disease Mutant of APP. Sci Rep 2019; 9:5321. [PMID: 30926830 PMCID: PMC6440955 DOI: 10.1038/s41598-019-41766-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 02/27/2019] [Indexed: 12/15/2022] Open
Abstract
Cleavage of the amyloid precursor protein's (APP) transmembrane domain (TMD) by γ-secretase is a crucial step in the aetiology of Alzheimer's Disease (AD). Mutations in the APP TMD alter cleavage and lead to familial forms of AD (FAD). The majority of FAD mutations shift the preference of initial cleavage from ε49 to ε48, thus raising the AD-related Aβ42/Aβ40 ratio. The I45T mutation is among the few FAD mutations that do not alter ε-site preference, while it dramatically reduces the efficiency of ε-cleavage. Here, we investigate the impact of the I45T mutation on the backbone dynamics of the substrate TMD. Amide exchange experiments and molecular dynamics simulations in solvent and a lipid bilayer reveal an increased stability of amide hydrogen bonds at the ζ- and γ-cleavage sites. Stiffening of the H-bond network is caused by an additional H-bond between the T45 side chain and the TMD backbone, which alters dynamics within the cleavage domain. In particular, the increased H-bond stability inhibits an upward movement of the ε-sites in the I45T mutant. Thus, an altered presentation of ε-sites to the active site of γ-secretase as a consequence of restricted local flexibility provides a rationale for reduced ε-cleavage efficiency of the I45T mutant.
Collapse
Grants
- Deutsche Forschungsgemeinschaft (German Research Foundation)
- Helmholtz-Gemeinschaft (Helmholtz Association)
- Leibniz Supercomputing Centre: Leibniz-Rechenzentrum der Bayerischen Akademie der Wissenschaften, Boltzmannstraße 1, 85748 Garching bei München, Germany, WEB: https://www.lrz.de Gauss Centre for Supercomputing: GCS-Geschäftsstelle Bonn, Ahrstrasse 45, 53175 Bonn, Germany, WEB: http://www.gauss-centre.eu
- Center for Integrated Protein Science: Munich Center For Integrated Protein Science (CIPSM), Butenandtstr. 5 - 13, 81377 Munich, Germany, WEB: http://www.cipsm.de/ Leibniz Supercomputing Centre: Leibniz-Rechenzentrum der Bayerischen Akademie der Wissenschaften, Boltzmannstraße 1, 85748 Garching bei München, Germany, WEB: https://www.lrz.de
Collapse
Affiliation(s)
- Alexander Götz
- Lehrstuhl für Physik synthetischer Biosysteme (E14), Technische Universität München, Maximus-von-Imhof Forum 4, 85354, Freising, Germany
| | - Philipp Högel
- Center for Integrated Protein Science Munich (CIPSM) at the Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354, Freising, Germany
| | - Mara Silber
- Institute of Organic Chemistry and Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Iro Chaitoglou
- Center for Integrated Protein Science Munich (CIPSM) at the Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354, Freising, Germany
| | - Burkhard Luy
- Institute of Organic Chemistry and Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Claudia Muhle-Goll
- Institute of Organic Chemistry and Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Christina Scharnagl
- Lehrstuhl für Physik synthetischer Biosysteme (E14), Technische Universität München, Maximus-von-Imhof Forum 4, 85354, Freising, Germany.
| | - Dieter Langosch
- Center for Integrated Protein Science Munich (CIPSM) at the Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354, Freising, Germany.
| |
Collapse
|
16
|
Amyloid precursor protein-fragments-containing inclusions in cardiomyocytes with basophilic degeneration and its association with cerebral amyloid angiopathy and myocardial fibrosis. Sci Rep 2018; 8:16594. [PMID: 30413735 PMCID: PMC6226444 DOI: 10.1038/s41598-018-34808-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 10/26/2018] [Indexed: 12/12/2022] Open
Abstract
Cardiomyopathies with intracellular inclusions are a distinct subset of cardiomyopathies whereas basophilic degeneration (BD) of the heart describes inclusions in cardiomyocytes of the aging heart, which have not yet been related to a specific disease condition or to a distinct type of protein inclusion. To address the question whether BD represents a specific pathological feature and whether it is linked to a distinct disease condition we studied 62 autopsy cases. BD inclusions exhibited an immunohistochemical staining pattern related to glycosylated, δ- or η-secretase-derived N-terminal cleavage products of the amyloid precursor protein (sAPPδ/η) or shorter fragments of sAPPη. BD aggregates were found in the myocardium of both ventricles and atria with highest amounts in the atria and lowest in the interventricular septum. The frequency of BD-lesions correlated with age, degree of myocardial fibrosis in individuals with arterial hypertension, and the severity of cerebral amyloid angiopathy (CAA). The intracytoplasmic deposition of N-terminal sAPPδ/η fragments in BD indicates a specific inclusion body pathology related to APP metabolism. The correlation with the severity of CAA, which is related to the APP-derived amyloid β-protein, supports this point of view and suggests a possible link between myocardial and cerebrovascular APP-related lesions.
Collapse
|
17
|
Steiner H, Fukumori A, Tagami S, Okochi M. Making the final cut: pathogenic amyloid-β peptide generation by γ-secretase. Cell Stress 2018; 2:292-310. [PMID: 31225454 PMCID: PMC6551803 DOI: 10.15698/cst2018.11.162] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Alzheimer´s disease (AD) is a devastating neurodegenerative disease of the elderly population. Genetic evidence strongly suggests that aberrant generation and/or clearance of the neurotoxic amyloid-β peptide (Aβ) is triggering the disease. Aβ is generated from the amyloid precursor protein (APP) by the sequential cleavages of β- and γ-secretase. The latter cleavage by γ-secretase, a unique and fascinating four-component protease complex, occurs in the APP transmembrane domain thereby releasing Aβ species of 37-43 amino acids in length including the longer, highly pathogenic peptides Aβ42 and Aβ43. The lack of a precise understanding of Aβ generation as well as of the functions of other γ-secretase substrates has been one factor underlying the disappointing failure of γ-secretase inhibitors in clinical trials, but on the other side also been a major driving force for structural and in depth mechanistic studies on this key AD drug target in the past few years. Here we review recent breakthroughs in our understanding of how the γ-secretase complex recognizes substrates, of how it binds and processes β-secretase cleaved APP into different Aβ species, as well as the progress made on a question of outstanding interest, namely how clinical AD mutations in the catalytic subunit presenilin and the γ-secretase cleavage region of APP lead to relative increases of Aβ42/43. Finally, we discuss how the knowledge emerging from these studies could be used to therapeutically target this enzyme in a safe way.
Collapse
Affiliation(s)
- Harald Steiner
- Biomedical Center (BMC), Metabolic Biochemistry, Ludwig-Maximilians-University Munich, Germany.,German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Akio Fukumori
- Department of Aging Neurobiology, National Center for Geriatrics and Gerontology, Obu & Department of Mental Health Promotion, Osaka University Graduate School of Medicine, Toyonaka, Japan
| | - Shinji Tagami
- Neuropsychiatry, Department of Integrated Medicine, Division of Internal Medicine, Osaka University Graduate School of Medicine, Suita, Japan
| | - Masayasu Okochi
- Neuropsychiatry, Department of Integrated Medicine, Division of Internal Medicine, Osaka University Graduate School of Medicine, Suita, Japan
| |
Collapse
|
18
|
Götz A, Scharnagl C. Dissecting conformational changes in APP's transmembrane domain linked to ε-efficiency in familial Alzheimer's disease. PLoS One 2018; 13:e0200077. [PMID: 29966005 PMCID: PMC6028146 DOI: 10.1371/journal.pone.0200077] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 06/19/2018] [Indexed: 02/02/2023] Open
Abstract
The mechanism by which familial Alzheimer's disease (FAD) mutations within the transmembrane domain (TMD) of the Amyloid Precursor Protein (APP) affect ε-endoproteolysis is only poorly understood. Thereby, mutations in the cleavage domain reduce ε-efficiency of γ-secretase cleavage and some even shift entry into production lines. Since cleavage occurs within the TMD, a relationship between processing and TMD structure and dynamics seems obvious. Using molecular dynamic simulations, we dissect the dynamic features of wild-type and seven FAD-mutants into local and global components. Mutations consistently enhance hydrogen-bond fluctuations upstream of the ε-cleavage sites but maintain strong helicity there. Dynamic perturbation-response scanning reveals that FAD-mutants target backbone motions utilized in the bound state. Those motions, obscured by large-scale motions in the pre-bound state, provide (i) a dynamic mechanism underlying the proposed coupling between binding and ε-cleavage, (ii) key sites consistent with experimentally determined docking sites, and (iii) the distinction between mutants and wild-type.
Collapse
Affiliation(s)
- Alexander Götz
- Technical University of Munich, Chair of Physics of Synthetic Biological Systems, Freising, Germany
| | - Christina Scharnagl
- Technical University of Munich, Chair of Physics of Synthetic Biological Systems, Freising, Germany
| |
Collapse
|
19
|
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: 1.4] [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.
Collapse
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
| |
Collapse
|
20
|
Langosch D, Steiner H. Substrate processing in intramembrane proteolysis by γ-secretase - the role of protein dynamics. Biol Chem 2017; 398:441-453. [PMID: 27845877 DOI: 10.1515/hsz-2016-0269] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/08/2016] [Indexed: 01/31/2023]
Abstract
Intramembrane proteases comprise a number of different membrane proteins with different types of catalytic sites. Their common denominator is cleavage within the plane of the membrane, which usually results in peptide bond scission within the transmembrane helices of their substrates. Despite recent progress in the determination of high-resolution structures, as illustrated here for the γ-secretase complex and its substrate C99, it is still unknown how these enzymes function and how they distinguish between substrates and non-substrates. In principle, substrate/non-substrate discrimination could occur at the level of substrate binding and/or cleavage. Focusing on the γ-secretase/C99 pair, we will discuss recent observations suggesting that global motions within a substrate transmembrane helix may be much more important for defining a substrate than local unraveling at cleavage sites.
Collapse
|
21
|
Gerber H, Wu F, Dimitrov M, Garcia Osuna GM, Fraering PC. Zinc and Copper Differentially Modulate Amyloid Precursor Protein Processing by γ-Secretase and Amyloid-β Peptide Production. J Biol Chem 2017; 292:3751-3767. [PMID: 28096459 DOI: 10.1074/jbc.m116.754101] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 01/13/2017] [Indexed: 11/06/2022] Open
Abstract
Recent evidence suggests involvement of biometal homeostasis in the pathological mechanisms in Alzheimer's disease (AD). For example, increased intracellular copper or zinc has been linked to a reduction in secreted levels of the AD-causing amyloid-β peptide (Aβ). However, little is known about whether these biometals modulate the generation of Aβ. In the present study we demonstrate in both cell-free and cell-based assays that zinc and copper regulate Aβ production by distinct molecular mechanisms affecting the processing by γ-secretase of its Aβ precursor protein substrate APP-C99. We found that Zn2+ induces APP-C99 dimerization, which prevents its cleavage by γ-secretase and Aβ production, with an IC50 value of 15 μm Importantly, at this concentration, Zn2+ also drastically raised the production of the aggregation-prone Aβ43 found in the senile plaques of AD brains and elevated the Aβ43:Aβ40 ratio, a promising biomarker for neurotoxicity and AD. We further demonstrate that the APP-C99 histidine residues His-6, His-13, and His-14 control the Zn2+-dependent APP-C99 dimerization and inhibition of Aβ production, whereas the increased Aβ43:Aβ40 ratio is substrate dimerization-independent and involves the known Zn2+ binding lysine Lys-28 residue that orientates the APP-C99 transmembrane domain within the lipid bilayer. Unlike zinc, copper inhibited Aβ production by directly targeting the subunits presenilin and nicastrin in the γ-secretase complex. Altogether, our data demonstrate that zinc and copper differentially modulate Aβ production. They further suggest that dimerization of APP-C99 or the specific targeting of individual residues regulating the production of the long, toxic Aβ species, may offer two therapeutic strategies for preventing AD.
Collapse
Affiliation(s)
- Hermeto Gerber
- From the Foundation Eclosion, CH-1228 Plan-Les-Ouates, and Campus Biotech Innovation Park, CH-1202 Geneva, Switzerland.,the Brain Mind Institute and School of Life Sciences, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland.,the Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland, and
| | - Fang Wu
- the Brain Mind Institute and School of Life Sciences, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland.,the Key Laboratory of Systems Biomedicine, Ministry of Education, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, 200240 Shanghai, China
| | - Mitko Dimitrov
- the Brain Mind Institute and School of Life Sciences, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland
| | - Guillermo M Garcia Osuna
- the Brain Mind Institute and School of Life Sciences, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland
| | - Patrick C Fraering
- From the Foundation Eclosion, CH-1228 Plan-Les-Ouates, and Campus Biotech Innovation Park, CH-1202 Geneva, Switzerland, .,the Brain Mind Institute and School of Life Sciences, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland
| |
Collapse
|
22
|
γ-Secretase Modulators as Aβ42-Lowering Pharmacological Agents to Treat Alzheimer’s Disease. TOPICS IN MEDICINAL CHEMISTRY 2017. [DOI: 10.1007/7355_2016_19] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
|
23
|
Stelzer W, Scharnagl C, Leurs U, Rand KD, Langosch D. The Impact of the ‘Austrian’ Mutation of the Amyloid Precursor Protein Transmembrane Helix is Communicated to the Hinge Region. ChemistrySelect 2016. [DOI: 10.1002/slct.201601090] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Walter Stelzer
- Lehrstuhl Chemie der Biopolymere; Technical University of Munich and Munich Center for Integrated Protein Science (CIPS ); Weihenstephaner Berg 3 85354 Freising Germany
| | - Christina Scharnagl
- Fakultät für Physik E14; Technical University of Munich; Maximus-von-Imhof-Forum 4 85354 Freising Germany
| | - Ulrike Leurs
- Department of Pharmacy; University of Copenhagen; Universitetsparken 2 2100 Copenhagen Denmark
| | - Kasper D. Rand
- Department of Pharmacy; University of Copenhagen; Universitetsparken 2 2100 Copenhagen Denmark
| | - Dieter Langosch
- Lehrstuhl Chemie der Biopolymere; Technical University of Munich and Munich Center for Integrated Protein Science (CIPS ); Weihenstephaner Berg 3 85354 Freising Germany
| |
Collapse
|
24
|
Audagnotto M, Lemmin T, Barducci A, Dal Peraro M. Effect of the Synaptic Plasma Membrane on the Stability of the Amyloid Precursor Protein Homodimer. J Phys Chem Lett 2016; 7:3572-3578. [PMID: 27518597 DOI: 10.1021/acs.jpclett.6b01721] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The proteolytic cleavage of the transmembrane (TM) domain of the amyloid precursor protein (APP) releases amyloid-β (Aβ) peptides, which accumulation in the brain tissue is an early indicator of Alzheimer's disease. We used multiscale molecular dynamics simulations to investigate the stability of APP-TM dimer in realistic models of the synaptic plasma membrane (SPM). Between the two possible dimerization motifs proposed by NMR and EPR, namely G709XXXA713 and G700XXXG704XXXG708, our study revealed that the dimer promoted by the G709XXXA713 motif is not stable in the SPM due to the competition with highly unsaturated lipids that constitute the SPM. Under the same conditions, the dimer promoted by the G700XXXG704XXXG708 motif is instead the most stable species and likely the most biologically relevant. Independently of the dimerization state, both these motifs can be involved in the recruitment of cholesterol molecules.
Collapse
Affiliation(s)
- Martina Audagnotto
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL) , Lausanne 1015, Switzerland
- Swiss Institute of Bioinformatics (SIB) , Lausanne 1015, Switzerland
| | - Thomas Lemmin
- Department of Pharmaceutical Chemistry, University of California-San Francisco , San Francisco, California 94143, United States
| | - Alessandro Barducci
- Inserm, U1054 Montpellier, France
- Université de Montpellier, CNRS, UMR 5048 , Centre de Biochimie Structurale, U1054 Montpellier, France
| | - Matteo Dal Peraro
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL) , Lausanne 1015, Switzerland
- Swiss Institute of Bioinformatics (SIB) , Lausanne 1015, Switzerland
| |
Collapse
|
25
|
Conformational Changes in Transmembrane Domain 4 of Presenilin 1 Are Associated with Altered Amyloid-β 42 Production. J Neurosci 2016; 36:1362-72. [PMID: 26818522 DOI: 10.1523/jneurosci.5090-14.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED γ-Secretase is an intramembrane-cleaving protease that produces amyloid-β peptide 42 (Aβ42), which is the toxic and aggregation-prone species of Aβ that causes Alzheimer's disease. Here, we used the substituted cysteine accessibility method to analyze the structure of transmembrane domains (TMDs) 4 and 5 of human presenilin 1 (PS1), a catalytic subunit of γ-secretase. We revealed that TMD4 and TMD5 face the intramembranous hydrophilic milieu together with TMD1, TMD6, TMD7, and TMD9 of PS1 to form the catalytic pore structure. Notably, we found a correlation in the distance between the cytosolic sides of TMD4/TMD7 and Aβ42 production levels, suggesting that allosteric conformational changes of the cytosolic side of TMD4 affect Aβ42-generating γ-secretase activity. Our results provide new insights into the relationship between the structure and activity of human PS1. SIGNIFICANCE STATEMENT Modulation of γ-secretase activity to reduce toxic amyloid-β peptide species is one plausible therapeutic approaches for Alzheimer's disease. However, precise mechanistic information of γ-secretase still remains unclear. Here we identified the conformational changes in transmembrane domains of presenilin 1 that affect the proteolytic activity of the γ-secretase. Our results highlight the importance of understanding the structural dynamics of presenilin 1 in drug development against Alzheimer's disease.
Collapse
|
26
|
BIIB042, a novel γ-secretase modulator, reduces amyloidogenic Aβ isoforms in primates and rodents and plaque pathology in a mouse model of Alzheimer's disease. Neuropharmacology 2016; 103:57-68. [DOI: 10.1016/j.neuropharm.2015.12.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 11/16/2015] [Accepted: 12/09/2015] [Indexed: 12/16/2022]
|
27
|
Kamp F, Winkler E, Trambauer J, Ebke A, Fluhrer R, Steiner H. Intramembrane proteolysis of β-amyloid precursor protein by γ-secretase is an unusually slow process. Biophys J 2016; 108:1229-37. [PMID: 25762334 DOI: 10.1016/j.bpj.2014.12.045] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 12/19/2014] [Accepted: 12/29/2014] [Indexed: 11/16/2022] Open
Abstract
Intramembrane proteolysis has emerged as a key mechanism required for membrane proteostasis and cellular signaling. One of the intramembrane-cleaving proteases (I-CLiPs), γ-secretase, is also intimately implicated in Alzheimer's disease, a major neurodegenerative disease and leading cause of dementia. High-resolution crystal structural analyses have revealed that I-CLiPs harbor their active sites buried deeply in the membrane bilayer. Surprisingly, however, the key kinetic constants of these proteases, turnover number kcat and catalytic efficiency kcat/KM, are largely unknown. By investigating the kinetics of intramembrane cleavage of the Alzheimer's disease-associated β-amyloid precursor protein in vitro and in human embryonic kidney cells, we show that γ-secretase is a very slow protease with a kcat value similar to those determined recently for rhomboid-type I-CLiPs. Our results indicate that low turnover numbers may be a general feature of I-CLiPs.
Collapse
Affiliation(s)
- Frits Kamp
- Metabolic Biochemistry, Ludwig-Maximilians-University, München, Germany
| | - Edith Winkler
- Metabolic Biochemistry, Ludwig-Maximilians-University, München, Germany
| | | | - Amelie Ebke
- Metabolic Biochemistry, Ludwig-Maximilians-University, München, Germany
| | - Regina Fluhrer
- Metabolic Biochemistry, Ludwig-Maximilians-University, München, Germany; DZNE-German Center for Neurodegenerative Diseases, Munich, Germany
| | - Harald Steiner
- Metabolic Biochemistry, Ludwig-Maximilians-University, München, Germany; DZNE-German Center for Neurodegenerative Diseases, Munich, Germany.
| |
Collapse
|
28
|
Winkler E, Julius A, Steiner H, Langosch D. Homodimerization Protects the Amyloid Precursor Protein C99 Fragment from Cleavage by γ-Secretase. Biochemistry 2015; 54:6149-52. [DOI: 10.1021/acs.biochem.5b00986] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Edith Winkler
- BMC-Biomedical
Center, Metabolic Biochemistry, Ludwig-Maximilians-University, Munich, Germany
| | - Ayse Julius
- Lehrstuhl
Chemie der Biopolymere, Technische Universität München, Weihenstephaner
Berg 3, 85354 Freising, Germany
- Munich Center For Integrated Protein Science (CIPSM), Munich, Germany
| | - Harald Steiner
- BMC-Biomedical
Center, Metabolic Biochemistry, Ludwig-Maximilians-University, Munich, Germany
- DZNE-German Center for Neurodegenerative Diseases, Munich, Germany
| | - Dieter Langosch
- Lehrstuhl
Chemie der Biopolymere, Technische Universität München, Weihenstephaner
Berg 3, 85354 Freising, Germany
- Munich Center For Integrated Protein Science (CIPSM), Munich, Germany
| |
Collapse
|
29
|
Potent benzoazepinone γ-secretase modulators with improved bioavailability. Bioorg Med Chem Lett 2015; 25:3495-500. [DOI: 10.1016/j.bmcl.2015.06.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Revised: 06/04/2015] [Accepted: 06/08/2015] [Indexed: 11/22/2022]
|
30
|
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: 89] [Impact Index Per Article: 8.9] [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.
Collapse
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
| |
Collapse
|
31
|
Oestereich F, Bittner HJ, Weise C, Grohmann L, Janke LK, Hildebrand PW, Multhaup G, Munter LM. Impact of amyloid precursor protein hydrophilic transmembrane residues on amyloid-beta generation. Biochemistry 2015; 54:2777-84. [PMID: 25875527 DOI: 10.1021/acs.biochem.5b00217] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Amyloid-β (Aβ) peptides are likely the molecular cause of neurodegeneration observed in Alzheimer's disease. In the brain, Aβ42 and Aβ40 are toxic and the most important proteolytic fragments generated through sequential processing of the amyloid precursor protein (APP) by β- and γ-secretases. Impeding the generation of Aβ42 and Aβ40 is thus considered as a promising strategy to prevent Alzheimer's disease. We therefore wanted to determine key parameters of the APP transmembrane sequence enabling production of these Aβ species. Here we show that the hydrophilicity of amino acid residues G33, T43, and T48 critically determines the generation of Aβ42 and Aβ40 peptides (amino acid numbering according to Aβ nomenclature starting with aspartic acid 1). First, we performed a comprehensive mutational analysis of glycine residue G33 positioned within the N-terminal half of the APP transmembrane sequence by exchanging it against the 19 other amino acids. We found that hydrophilicity of the residue at position 33 positively correlated with Aβ42 and Aβ40 generation. Second, we analyzed two threonine residues at positions T43 and T48 in the C-terminal half of the APP-transmembrane sequence. Replacement of single threonine residues by hydrophobic valines inversely affected Aβ42 and Aβ40 generation. We observed that threonine mutants affected the initial γ-secretase cut, which is associated with levels of Aβ42 or Aβ40. Overall, hydrophilic residues of the APP transmembrane sequence decide on the exact initial γ-cut and the amounts of Aβ42 and Aβ40.
Collapse
Affiliation(s)
- Felix Oestereich
- †Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir William Osler, H3G 1Y6 Montréal, Canada.,‡Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany.,∥Integrated Program in Neuroscience, McGill University, Montréal, Canada
| | - Heiko J Bittner
- §Institut für Medizinische Physik und Biophysik, Charité, Charitéplatz 1, 10117 Berlin, Germany
| | - Christoph Weise
- ‡Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Lisa Grohmann
- ‡Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Lisa-Kristin Janke
- ‡Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Peter W Hildebrand
- §Institut für Medizinische Physik und Biophysik, Charité, Charitéplatz 1, 10117 Berlin, Germany
| | - Gerhard Multhaup
- †Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir William Osler, H3G 1Y6 Montréal, Canada.,‡Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Lisa-Marie Munter
- †Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir William Osler, H3G 1Y6 Montréal, Canada.,‡Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| |
Collapse
|
32
|
Scharnagl C, Pester O, Hornburg P, Hornburg D, Götz A, Langosch D. Side-chain to main-chain hydrogen bonding controls the intrinsic backbone dynamics of the amyloid precursor protein transmembrane helix. Biophys J 2014; 106:1318-26. [PMID: 24655507 DOI: 10.1016/j.bpj.2014.02.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 01/28/2014] [Accepted: 02/07/2014] [Indexed: 01/19/2023] Open
Abstract
Many transmembrane helices contain serine and/or threonine residues whose side chains form intrahelical H-bonds with upstream carbonyl oxygens. Here, we investigated the impact of threonine side-chain/main-chain backbonding on the backbone dynamics of the amyloid precursor protein transmembrane helix. This helix consists of a N-terminal dimerization region and a C-terminal cleavage region, which is processed by γ-secretase to a series of products. Threonine mutations within this transmembrane helix are known to alter the cleavage pattern, which can lead to early-onset Alzheimer's disease. Circular dichroism spectroscopy and amide exchange experiments of synthetic transmembrane domain peptides reveal that mutating threonine enhances the flexibility of this helix. Molecular dynamics simulations show that the mutations reduce intrahelical amide H-bonding and H-bond lifetimes. In addition, the removal of side-chain/main-chain backbonding distorts the helix, which alters bending and rotation at a diglycine hinge connecting the dimerization and cleavage regions. We propose that the backbone dynamics of the substrate profoundly affects the way by which the substrate is presented to the catalytic site within the enzyme. Changing this conformational flexibility may thus change the pattern of proteolytic processing.
Collapse
Affiliation(s)
| | - Oxana Pester
- Munich Center for Integrated Protein Science (CIPS(M)) at Lehrstuhl Chemie der Biopolymere, Technische Universität München, Freising, Germany
| | - Philipp Hornburg
- Fakultät für Physik E14, Technische Universität München, Freising, Germany
| | - Daniel Hornburg
- Fakultät für Physik E14, Technische Universität München, Freising, Germany
| | - Alexander Götz
- Munich Center for Integrated Protein Science (CIPS(M)) at Lehrstuhl Chemie der Biopolymere, Technische Universität München, Freising, Germany
| | - Dieter Langosch
- Munich Center for Integrated Protein Science (CIPS(M)) at Lehrstuhl Chemie der Biopolymere, Technische Universität München, Freising, Germany
| |
Collapse
|
33
|
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: 1.4] [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.
Collapse
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
| | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Lemmin T, Dimitrov M, Fraering PC, Dal Peraro M. Perturbations of the straight transmembrane α-helical structure of the amyloid precursor protein affect its processing by γ-secretase. J Biol Chem 2014; 289:6763-6774. [PMID: 24469457 PMCID: PMC3945338 DOI: 10.1074/jbc.m113.470781] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Revised: 01/14/2014] [Indexed: 01/30/2023] Open
Abstract
The amyloid precursor protein (APP) is a widely expressed type I transmembrane (TM) glycoprotein present at the neuronal synapse. The proteolytic cleavage by γ-secretase of its C-terminal fragment produces amyloid-β (Aβ) peptides of different lengths, the deposition of which is an early indicator of Alzheimer disease. At present, there is no consensus on the conformation of the APP-TM domain at the biological membrane. Although structures have been determined by NMR in detergent micelles, their conformation is markedly different. Here we show by using molecular simulations that the APP-TM region systematically prefers a straight α-helical conformation once embedded in a membrane bilayer. However, APP-TM is highly flexible, and its secondary structure is strongly influenced by the surrounding lipid environment, as when enclosed in detergent micelles. This behavior is confirmed when analyzing in silico the atomistic APP-TM population observed by residual dipolar couplings and double electron-electron resonance spectroscopy. These structural and dynamic features are critical in the proteolytic processing of APP by the γ-secretase enzyme, as suggested by a series of Gly(700) mutants. Affecting the hydration and flexibility of APP-TM, these mutants invariantly show an increase in the production of Aβ38 compared with Aβ40 peptides, which is reminiscent of the effect of γ-secretase modulators inhibitors.
Collapse
Affiliation(s)
- Thomas Lemmin
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland; Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Mitko Dimitrov
- Brain Mind Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Patrick C Fraering
- Brain Mind Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Matteo Dal Peraro
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland; Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland.
| |
Collapse
|
35
|
Wagner SL, Zhang C, Cheng S, Nguyen P, Zhang X, Rynearson K, Wang R, Li Y, Sisodia SS, Mobley WC, Tanzi RE. Soluble γ-secretase modulators selectively inhibit the production of the 42-amino acid amyloid β peptide variant and augment the production of multiple carboxy-truncated amyloid β species. Biochemistry 2014; 53:702-13. [PMID: 24401146 PMCID: PMC3929337 DOI: 10.1021/bi401537v] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/07/2014] [Indexed: 02/05/2023]
Abstract
Alzheimer's disease (AD) is characterized pathologically by an abundance of extracellular neuritic plaques composed primarily of the 42-amino acid amyloid β peptide variant (Aβ42). In the majority of familial AD (FAD) cases, e.g., those harboring mutations in presenilin 1 (PS1), there is a relative increase in the levels of Aβ42 compared to the levels of Aβ40. We previously reported the characterization of a series of aminothiazole-bridged aromates termed aryl aminothiazole γ-secretase modulators or AGSMs [Kounnas, M. Z., et al. (2010) Neuron 67, 769-780] and showed their potential for use in the treatment of FAD [Wagner, S. L., et al. (2012) Arch. Neurol. 69, 1255-1258]. Here we describe a series of GSMs with physicochemical properties improved compared to those of AGSMs. Specific heterocycle replacements of the phenyl rings in AGSMs provided potent molecules with improved aqueous solubilities. A number of these soluble γ-secretase modulators (SGSMs) potently lowered Aβ42 levels without inhibiting proteolysis of Notch or causing accumulation of amyloid precursor protein carboxy-terminal fragments, even at concentrations approximately 1000-fold greater than their IC50 values for reducing Aβ42 levels. The effects of one potent SGSM on Aβ peptide production were verified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, showing enhanced production of a number of carboxy-truncated Aβ species. This SGSM also inhibited Aβ42 peptide production in a highly purified reconstituted γ-secretase in vitro assay system and retained the ability to modulate γ-secretase-mediated proteolysis in a stably transfected cell culture model overexpressing a human PS1 mutation validating the potential for use in FAD.
Collapse
Affiliation(s)
- Steven L. Wagner
- Department
of Neurosciences, University of California,
San Diego, La Jolla, California 92093-0624, United States
| | - Can Zhang
- Genetics
and Aging Research Unit, Department of Neurology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Soan Cheng
- Department
of Neurosciences, University of California,
San Diego, La Jolla, California 92093-0624, United States
| | - Phuong Nguyen
- Department
of Neurosciences, University of California,
San Diego, La Jolla, California 92093-0624, United States
| | - Xulun Zhang
- The
Center for Molecular Neurobiology, University
of Chicago, Chicago, Illinois 60637, United
States
| | - Kevin
D. Rynearson
- Department
of Neurosciences, University of California,
San Diego, La Jolla, California 92093-0624, United States
| | - Rong Wang
- Department
of Genetics and Genomic Sciences, Icahn
Institute, New York, New York 10029, United
States
| | - Yueming Li
- Molecular
Pharmacology and Chemistry Program, Memorial
Sloan-Kettering Cancer Center, New York, New York 10065, United States
| | - Sangram S. Sisodia
- The
Center for Molecular Neurobiology, University
of Chicago, Chicago, Illinois 60637, United
States
| | - William C. Mobley
- Department
of Neurosciences, University of California,
San Diego, La Jolla, California 92093-0624, United States
| | - Rudolph E. Tanzi
- Genetics
and Aging Research Unit, Department of Neurology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| |
Collapse
|
36
|
Suárez-Calvet M, Belbin O, Pera M, Badiola N, Magrané J, Guardia-Laguarta C, Muñoz L, Colom-Cadena M, Clarimón J, Lleó A. Autosomal-dominant Alzheimer's disease mutations at the same codon of amyloid precursor protein differentially alter Aβ production. J Neurochem 2013; 128:330-9. [PMID: 24117942 DOI: 10.1111/jnc.12466] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 09/20/2013] [Accepted: 10/24/2013] [Indexed: 02/02/2023]
Abstract
Autosomal-dominant Alzheimer's disease (ADAD) is a genetic disorder caused by mutations in Amyloid Precursor Protein (APP) or Presenilin (PSEN) genes. Studying the mechanisms underlying these mutations can provide insight into the pathways that lead to AD pathology. The majority of biochemical studies on APP mutations to-date have focused on comparing mechanisms between mutations at different codons. It has been assumed that amino acid position is a major determinant of protein dysfunction and clinical phenotype. However, the differential effect of mutations at the same codon has not been sufficiently addressed. In the present study we compared the effects of the aggressive ADAD-associated APP I716F mutation with I716V and I716T on APP processing in human neuroglioma and CHO-K1 cells. All APP I716 mutations increased the ratio of Aβ42/40 and changed the product line preference of γ-secretase towards Aβ38 production. In addition, the APP I716F mutation impaired the ε-cleavage and the fourth cleavage of γ-secretase and led to abnormal APP β-CTF accumulation at the plasma membrane. Taken together, these data indicate that APP mutations at the same codon can induce diverse abnormalities in APP processing, some resembling PSEN1 mutations. These differential effects could explain the clinical differences observed among ADAD patients bearing different APP mutations at the same position. The amyloid precursor protein (APP) I716F mutation is associated with autosomal dominant Alzheimer's disease with the youngest age-at-onset for the APP locus. Here, we describe that this mutation, when compared to two other familial Alzheimer's disease mutations at the same codon (I716V and I716T), interfered distinctly with γ-secretase cleavage. While all three mutations direct γ-secretase cleavage towards the 48→38 production line, the APP I716F mutation also impaired the ε-cleavage and the fourth cleavage of γ-secretase, resembling a PSEN1 mutation. These features may contribute to the aggressiveness of this mutation.
Collapse
Affiliation(s)
- Marc Suárez-Calvet
- Department of Neurology, Memory Disorders Unit, Hospital de la Santa Creu i Sant Pau, IIB-Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Alzheimer Laboratory, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | | | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Clustering of plaques contributes to plaque growth in a mouse model of Alzheimer's disease. Acta Neuropathol 2013; 126:179-88. [PMID: 23775142 PMCID: PMC3722456 DOI: 10.1007/s00401-013-1137-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 05/29/2013] [Indexed: 01/20/2023]
Abstract
Amyloid-β (Aβ) plaque deposition plays a central role in the pathogenesis of Alzheimer’s disease (AD). Post-mortem analysis of plaque development in mouse models of AD revealed that plaques are initially small, but then increase in size and become more numerous with age. There is evidence that plaques can grow uniformly over time; however, a complementary hypothesis of plaque development is that small plaques cluster and grow together thereby forming larger plaques. To investigate the latter hypothesis, we studied plaque formation in APPPS1 mice using in vivo two-photon microscopy and immunohistochemical analysis. We used sequential pre- and post-mortem staining techniques to label plaques at different stages of development and to detect newly emerged plaques. Post-mortem analysis revealed that a subset (22 %) of newly formed plaques appeared very close (<40 μm) to pre-existing plaques and that many close plaques (25 %) that were initially separate merged over time to form one single large plaque. Our results suggest that small plaques can cluster together, thus forming larger plaques as a complementary mechanism to simple uniform plaque growth from a single initial plaque. This study deepens our understanding of Aβ deposition and demonstrates that there are multiple mechanisms at play in plaque development.
Collapse
|
38
|
Song Y, Hustedt EJ, Brandon S, Sanders CR. Competition between homodimerization and cholesterol binding to the C99 domain of the amyloid precursor protein. Biochemistry 2013; 52:5051-64. [PMID: 23865807 DOI: 10.1021/bi400735x] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The 99-residue transmembrane C-terminal domain (C99, also known as β-CTF) of the amyloid precursor protein (APP) is the product of the β-secretase cleavage of the full-length APP and is the substrate for γ-secretase cleavage. The latter cleavage releases the amyloid-β polypeptides that are closely associated with Alzheimer's disease. C99 is thought to form homodimers; however, the free energy in favor of dimerization has not previously been quantitated. It was also recently documented that cholesterol forms a 1:1 complex with monomeric C99 in bicelles. Here, the affinities for both homodimerization and cholesterol binding to C99 were measured in bilayered lipid vesicles using both electron paramagnetic resonance (EPR) and Förster resonance energy transfer (FRET) methods. Homodimerization and cholesterol binding were seen to be competitive processes that center on the transmembrane G₇₀₀XXXG₇₀₄XXXG₇₀₈ glycine-zipper motif and adjacent Gly709. On one hand, the observed Kd for cholesterol binding (Kd = 2.7 ± 0.3 mol %) is on the low end of the physiological cholesterol concentration range in mammalian cell membranes. On the other hand, the observed K(d) for homodimerization (K(d) = 0.47 ± 0.15 mol %) likely exceeds the physiological concentration range for C99. These results suggest that the 1:1 cholesterol/C99 complex will be more highly populated than C99 homodimers under most physiological conditions. These observations are of relevance for understanding the γ-secretase cleavage of C99.
Collapse
Affiliation(s)
- Yuanli Song
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | | | | | | |
Collapse
|
39
|
Crump CJ, Johnson DS, Li YM. Development and mechanism of γ-secretase modulators for Alzheimer's disease. Biochemistry 2013; 52:3197-216. [PMID: 23614767 DOI: 10.1021/bi400377p] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
γ-Secretase is an aspartyl intramembranal protease composed of presenilin, Nicastrin, Aph1, and Pen2 with 19 transmembrane domains. γ-Secretase cleaves the amyloid precursor proteins (APP) to release Aβ peptides that likely play a causative role in the pathogenesis of Alzheimer's disease (AD). In addition, γ-secretase cleaves Notch and other type I membrane proteins. γ-Secretase inhibitors (GSIs) have been developed and used for clinical studies. However, clinical trials have shown adverse effects of GSIs that are potentially linked with nondiscriminatory inhibition of Notch signaling, overall APP processing, and other substrate cleavages. Therefore, these findings call for the development of disease-modifying agents that target γ-secretase activity to lower levels of Aβ42 production without blocking the overall processing of γ-secretase substrates. γ-Secretase modulators (GSMs) originally derived from nonsteroidal anti-inflammatory drugs (NSAIDs) display such characteristics and are the focus of this review. However, first-generation GSMs have limited potential because of the low potency and undesired neuropharmacokinetic properties. This generation of GSMs has been suggested to interact with the APP substrate, γ-secretase, or both. To improve the potency and brain availability, second-generation GSMs, including NSAID-derived carboxylic acid and non-NSAID-derived heterocyclic chemotypes, as well as natural product-derived GSMs have been developed. Animal studies of this generation of GSMs have shown encouraging preclinical profiles. Moreover, using potent GSM photoaffinity probes, multiple studies unambiguously have showed that both carboxylic acid and heterocyclic GSMs specifically target presenilin, the catalytic subunit of γ-secretase. In addition, two types of GSMs have distinct binding sites within the γ-secretase complex and exhibit different Aβ profiles. GSMs induce a conformational change of γ-secretase to achieve modulation. Various models are proposed and discussed. Despite the progress of GSM research, many outstanding issues remain to be investigated to achieve the ultimate goal of developing GSMs as effective AD therapies.
Collapse
Affiliation(s)
- Christina J Crump
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center , 1275 York Avenue, New York, New York 10065, United States
| | | | | |
Collapse
|
40
|
Loss of PAFAH1B2 reduces amyloid-β generation by promoting the degradation of amyloid precursor protein C-terminal fragments. J Neurosci 2013; 32:18204-14. [PMID: 23238734 DOI: 10.1523/jneurosci.2681-12.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Amyloid-β peptide (Aβ) is believed to play a central role in the pathogenesis of Alzheimer's disease. In view of the side effects associated with inhibiting the secretases that produce Aβ, new molecular targets are required to provide alternative therapeutic options. We used RNA interference (RNAi) to systematically screen the Drosophila genome to identify genes that modulate Aβ production upon knockdown. RNAi of 41 genes in Drosophila cells significantly lowered Aβ without affecting general secretion or viability. After the γ-secretase complex components, the most potent effect was observed for platelet activating factor acetylhydrolase α (Paf-AHα), and, in mammalian cells, the effect was replicated for its ortholog PAFAH1B2. Knockdown of PAFAH1B2 strongly reduced Aβ secretion from human cells, and this effect was confirmed in primary cells derived from PAFAH1B2 knock-out mice. Reduced Aβ production was not attributable to altered β-amyloid precursor protein (APP) ectodomain shedding but was a result of an enhanced degradation of APP C-terminal fragments (CTFs) in the absence of PAFAH1B2 but not its close homolog PAFAH1B3. Enhanced degradation of APP CTFs was selective because no such effects were obtained for Notch or E-/N-cadherin. Thus, we have identified an important protein that can selectively modify Aβ generation via a novel mechanism, namely enhanced degradation of its immediate precursor. In view of the absence of a neurological phenotype in PAFAH1B2 knock-out mice, targeted downregulation of PAFAH1B2 may be a promising new strategy for lowering Aβ.
Collapse
|
41
|
Pester O, Barrett PJ, Hornburg D, Hornburg P, Pröbstle R, Widmaier S, Kutzner C, Dürrbaum M, Kapurniotu A, Sanders CR, Scharnagl C, Langosch D. The backbone dynamics of the amyloid precursor protein transmembrane helix provides a rationale for the sequential cleavage mechanism of γ-secretase. J Am Chem Soc 2013; 135:1317-29. [PMID: 23265086 PMCID: PMC3560327 DOI: 10.1021/ja3112093] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The etiology of Alzheimer's disease depends on the relative abundance of different amyloid-β (Aβ) peptide species. These peptides are produced by sequential proteolytic cleavage within the transmembrane helix of the 99 residue C-terminal fragment of the amyloid precursor protein (C99) by the intramembrane protease γ-secretase. Intramembrane proteolysis is thought to require local unfolding of the substrate helix, which has been proposed to be cleaved as a homodimer. Here, we investigated the backbone dynamics of the substrate helix. Amide exchange experiments of monomeric recombinant C99 and of synthetic transmembrane domain peptides reveal that the N-terminal Gly-rich homodimerization domain exchanges much faster than the C-terminal cleavage region. MD simulations corroborate the differential backbone dynamics, indicate a bending motion at a diglycine motif connecting dimerization and cleavage regions, and detect significantly different H-bond stabilities at the initial cleavage sites. Our results are consistent with the following hypotheses about cleavage of the substrate: First, the GlyGly hinge may precisely position the substrate within γ-secretase such that its catalytic center must start proteolysis at the known initial cleavage sites. Second, the ratio of cleavage products formed by subsequent sequential proteolysis could be influenced by differential extents of solvation and by the stabilities of H-bonds at alternate initial sites. Third, the flexibility of the Gly-rich domain may facilitate substrate movement within the enzyme during sequential proteolysis. Fourth, dimerization may affect substrate processing by decreasing the dynamics of the dimerization region and by increasing that of the C-terminal part of the cleavage region.
Collapse
Affiliation(s)
- Oxana Pester
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Paul J. Barrett
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, Tennessee USA 37232-8725
| | - Daniel Hornburg
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Philipp Hornburg
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Rasmus Pröbstle
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Simon Widmaier
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Christoph Kutzner
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Milena Dürrbaum
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Aphrodite Kapurniotu
- Fachgebiet Peptidbiochemie, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising, Germany
| | - Charles R. Sanders
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, Tennessee USA 37232-8725
| | - Christina Scharnagl
- Fakultät für Physik E14, Technische Universität München, Maximus-von-Imhof-Forum 4, 85354 Freising, Germany
| | - Dieter Langosch
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| |
Collapse
|
42
|
Ousson S, Saric A, Baguet A, Losberger C, Genoud S, Vilbois F, Permanne B, Hussain I, Beher D. Substrate determinants in the C99 juxtamembrane domains differentially affect γ-secretase cleavage specificity and modulator pharmacology. J Neurochem 2013; 125:610-9. [PMID: 23253155 DOI: 10.1111/jnc.12129] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 12/12/2012] [Accepted: 12/13/2012] [Indexed: 11/29/2022]
Abstract
The molecular mechanisms governing γ-secretase cleavage specificity are not fully understood. Herein, we demonstrate that extending the transmembrane domain of the amyloid precursor protein-derived C99 substrate in proximity to the cytosolic face strongly influences γ-secretase cleavage specificity. Sequential insertion of leucines or replacement of membrane-anchoring lysines by leucines elevated the production of Aβ42, whilst lowering production of Aβ40. A single insertion or replacement was sufficient to produce this phenotype, suggesting that the helical length distal to the ε-site is a critical determinant of γ-secretase cleavage specificity. Replacing the lysine at the luminal membrane border (K28) with glutamic acid (K28E) increased Aβ37 and reduced Aβ42 production. Maintaining a positive charge with an arginine replacement, however, did not alter cleavage specificity. Using two potent and structurally distinct γ-secretase modulators (GSMs), we elucidated the contribution of K28 to the modulatory mechanism. Surprisingly, whilst lowering the potency of the non-steroidal anti-inflammatory drug-type GSM, the K28E mutation converted a heteroaryl-type GSM to an inverse GSM. This result implies the proximal lysine is critical for the GSM mechanism and pharmacology. This region is likely a major determinant for substrate binding and we speculate that modulation of substrate binding is the fundamental mechanism by which GSMs exert their action.
Collapse
Affiliation(s)
- Solenne Ousson
- Global Research and Early Development, Merck Serono SA, Geneva, Switzerland
| | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Kretner B, Fukumori A, Kuhn PH, Pérez-Revuelta BI, Lichtenthaler SF, Haass C, Steiner H. Important functional role of residue x of the presenilin GxGD protease active site motif for APP substrate cleavage specificity and substrate selectivity of γ-secretase. J Neurochem 2013; 125:144-56. [PMID: 23237322 DOI: 10.1111/jnc.12124] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 12/10/2012] [Accepted: 12/10/2012] [Indexed: 11/30/2022]
Abstract
γ-Secretase plays a central role in the generation of the Alzheimer disease-causing amyloid β-peptide (Aβ) from the β-amyloid precursor protein (APP) and is thus a major Alzheimer's disease drug target. As several other γ-secretase substrates including Notch1 and CD44 have crucial signaling functions, an understanding of the mechanism of substrate recognition and cleavage is key for the development of APP selective γ-secretase-targeting drugs. The γ-secretase active site domain in its catalytic subunit presenilin (PS) 1 has been implicated in substrate recognition/docking and cleavage. Highly critical in this process is its GxGD active site motif, whose invariant glycine residues cannot be replaced without causing severe functional losses in substrate selection and/or cleavage efficiency. Here, we have investigated the contribution of the less well characterized residue x of the motif (L383 in PS1) to this function. Extensive mutational analysis showed that processing of APP was overall well-tolerated over a wide range of hydrophobic and hydrophilic mutations. Interestingly, however, most L383 mutants gave rise to reduced levels of Aβ37-39 species, and several increased the pathogenic Aβ42/43 species. Several of the Aβ42/43 -increasing mutants severely impaired the cleavages of Notch1 and CD44 substrates, which were not affected by any other L383 mutation. Our data thus establish an important, but compared with the glycine residues of the motif, overall less critical functional role for L383. We suggest that L383 and the flanking glycine residues form a spatial arrangement in PS1 that is critical for docking and/or cleavage of different γ-secretase substrates.
Collapse
Affiliation(s)
- Benedikt Kretner
- Adolf-Butenandt-Institute, Biochemistry, Ludwig-Maximilians-University, Munich, Germany
| | | | | | | | | | | | | |
Collapse
|
44
|
Bulic B, Ness J, Hahn S, Rennhack A, Jumpertz T, Weggen S. Chemical Biology, Molecular Mechanism and Clinical Perspective of γ-Secretase Modulators in Alzheimer's Disease. Curr Neuropharmacol 2012; 9:598-622. [PMID: 22798753 PMCID: PMC3391656 DOI: 10.2174/157015911798376352] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 10/25/2010] [Accepted: 11/01/2010] [Indexed: 12/25/2022] Open
Abstract
Comprehensive evidence supports that oligomerization and accumulation of amyloidogenic Aβ42 peptides in brain is crucial in the pathogenesis of both familial and sporadic forms of Alzheimer's disease. Imaging studies indicate that the buildup of Aβ begins many years before the onset of clinical symptoms, and that subsequent neurodegeneration and cognitive decline may proceed independently of Aβ. This implies the necessity for early intervention in cognitively normal individuals with therapeutic strategies that prioritize safety. The aspartyl protease γ-secretase catalyses the last step in the cellular generation of Aβ42 peptides, and is a principal target for anti-amyloidogenic intervention strategies. Due to the essential role of γ-secretase in the NOTCH signaling pathway, overt mechanism-based toxicity has been observed with the first generation of γ-secretase inhibitors, and safety of this approach has been questioned. However, two new classes of small molecules, γ-secretase modulators (GSMs) and NOTCH-sparing γ-secretase inhibitors, have revitalized γ-secretase as a drug target in AD. GSMs are small molecules that cause a product shift from Aβ42 towards shorter and less toxic Ab peptides. Importantly, GSMs spare other physiologically important substrates of the γ-secretase complex like NOTCH. Recently, GSMs with nanomolar potency and favorable in vivo properties have been described. In this review, we summarize the knowledge about the unusual proteolytic activity of γ-secretase, and the chemical biology, molecular mechanisms and clinical perspective of compounds that target the γ-secretase complex, with a particular focus on GSMs.
Collapse
Affiliation(s)
- Bruno Bulic
- Research Group Chemical Biology of Neurodegenerative Diseases, Center of Advanced European Studies and Research, D-53175 Bonn, Germany
| | | | | | | | | | | |
Collapse
|
45
|
Wanngren J, Ottervald J, Parpal S, Portelius E, Strömberg K, Borgegård T, Klintenberg R, Juréus A, Blomqvist J, Blennow K, Zetterberg H, Lundkvist J, Rosqvist S, Karlström H. Second generation γ-secretase modulators exhibit different modulation of Notch β and Aβ production. J Biol Chem 2012; 287:32640-50. [PMID: 22851182 DOI: 10.1074/jbc.m112.376541] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The γ-secretase complex is an appealing drug target when the therapeutic strategy is to alter amyloid-β peptide (Aβ) aggregation in Alzheimer disease. γ-Secretase is directly involved in Aβ formation and determines the pathogenic potential of Aβ by generating the aggregation-prone Aβ42 peptide. Because γ-secretase mediates cleavage of many substrates involved in cell signaling, such as the Notch receptor, it is crucial to sustain these pathways while altering the Aβ secretion. A way of avoiding interference with the physiological function of γ-secretase is to use γ-secretase modulators (GSMs) instead of inhibitors of the enzyme. GSMs modify the Aβ formation from producing the amyloid-prone Aβ42 variant to shorter and less amyloidogenic Aβ species. The modes of action of GSMs are not fully understood, and even though the pharmacology of GSMs has been thoroughly studied regarding Aβ generation, knowledge is lacking about their effects on other substrates, such as Notch. Here, using immunoprecipitation followed by MALDI-TOF MS analysis, we found that two novel, second generation GSMs modulate both Notch β and Aβ production. Moreover, by correlating S3-specific Val-1744 cleavage of Notch intracellular domain (Notch intracellular domain) to total Notch intracellular domain levels using immunocytochemistry, we also demonstrated that Notch intracellular domain is not modulated by the compounds. Interestingly, two well characterized, nonsteroidal anti-inflammatory drugs (nonsteroidal anti-inflammatory drug), R-flurbiprofen and sulindac sulfide, affect only Aβ and not Notch β formation, indicating that second generation GSMs and nonsteroidal anti-inflammatory drug-based GSMs have different modes of action regarding Notch processing.
Collapse
Affiliation(s)
- Johanna Wanngren
- Department of Neurobiology, Care Sciences and society, KI-Alzheimer's Disease Research Center, Karolinska Institutet, 14157 Stockholm, Sweden
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Weggen S, Beher D. Molecular consequences of amyloid precursor protein and presenilin mutations causing autosomal-dominant Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2012; 4:9. [PMID: 22494386 PMCID: PMC3334542 DOI: 10.1186/alzrt107] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mutations in both the amyloid precursor protein (APP) and the presenilin (PSEN) genes cause familial Alzheimer's disease (FAD) with autosomal dominant inheritance and early onset of disease. The clinical course and neuropathology of FAD and sporadic Alzheimer's disease are highly similar, and patients with FAD constitute a unique population in which to conduct treatment and, in particular, prevention trials with novel pharmaceutical entities. It is critical, therefore, to exactly defi ne the molecular consequences of APP and PSEN FAD mutations. Both APP and PSEN mutations drive amyloidosis in FAD patients through changes in the brain metabolism of amyloid-β (Aβ) peptides that promote the formation of pathogenic aggregates. APP mutations do not seem to impair the physiological functions of APP. In contrast, it has been proposed that PSEN mutations compromise γ-secretase-dependent and -independent functions of PSEN. However, PSEN mutations have mostly been studied in model systems that do not accurately refl ect the genetic background in FAD patients. In this review, we discuss the reported cellular phenotypes of APP and PSEN mutations, the current understanding of their molecular mechanisms, the need to generate faithful models of PSEN mutations, and the potential bias of APP and PSEN mutations on therapeutic strategies that target Aβ.
Collapse
Affiliation(s)
- Sascha Weggen
- Department of Neuropathology, Heinrich-Heine-University, Moorenstrasse 5, D-40225 Düsseldorf, Germany.
| | | |
Collapse
|
47
|
Jumpertz T, Rennhack A, Ness J, Baches S, Pietrzik CU, Bulic B, Weggen S. Presenilin is the molecular target of acidic γ-secretase modulators in living cells. PLoS One 2012; 7:e30484. [PMID: 22238696 PMCID: PMC3253113 DOI: 10.1371/journal.pone.0030484] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 12/16/2011] [Indexed: 01/19/2023] Open
Abstract
The intramembrane-cleaving protease γ-secretase catalyzes the last step in the generation of toxic amyloid-β (Aβ) peptides and is a principal therapeutic target in Alzheimer's disease. Both preclinical and clinical studies have demonstrated that inhibition of γ-secretase is associated with prohibitive side effects due to suppression of Notch processing and signaling. Potentially safer are γ-secretase modulators (GSMs), which are small molecules that selectively lower generation of the highly amyloidogenic Aβ42 peptides but spare Notch processing. GSMs with nanomolar potency and favorable pharmacological properties have been described, but the molecular mechanism of GSMs remains uncertain and both the substrate amyloid precursor protein (APP) and subunits of the γ-secretase complex have been proposed as the molecular target of GSMs. We have generated a potent photo-probe based on an acidic GSM that lowers Aβ42 generation with an IC50 of 290 nM in cellular assays. By combining in vivo photo-crosslinking with affinity purification, we demonstrated that this probe binds the N-terminal fragment of presenilin (PSEN), the catalytic subunit of the γ-secretase complex, in living cells. Labeling was not observed for APP or any of the other γ-secretase subunits. Binding was readily competed by structurally divergent acidic and non-acidic GSMs suggesting a shared mode of action. These findings indicate that potent acidic GSMs target presenilin to modulate the enzymatic activity of the γ-secretase complex.
Collapse
Affiliation(s)
- Thorsten Jumpertz
- Department of Neuropathology, Heinrich-Heine-University, Duesseldorf, Germany
| | - Andreas Rennhack
- Research Group Chemical Biology of Neurodegenerative Diseases, Center of Advanced European Studies and Research, Bonn, Germany
| | - Julia Ness
- Department of Neuropathology, Heinrich-Heine-University, Duesseldorf, Germany
| | - Sandra Baches
- Department of Neuropathology, Heinrich-Heine-University, Duesseldorf, Germany
| | - Claus U. Pietrzik
- Molecular Neurodegeneration Group, Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Bruno Bulic
- Research Group Chemical Biology of Neurodegenerative Diseases, Center of Advanced European Studies and Research, Bonn, Germany
- * E-mail: (BB); (SW)
| | - Sascha Weggen
- Department of Neuropathology, Heinrich-Heine-University, Duesseldorf, Germany
- * E-mail: (BB); (SW)
| |
Collapse
|
48
|
So PP, Zeldich E, Seyb KI, Huang MM, Concannon JB, King GD, Chen CD, Cuny GD, Glicksman MA, Abraham CR. Lowering of amyloid beta peptide production with a small molecule inhibitor of amyloid-β precursor protein dimerization. AMERICAN JOURNAL OF NEURODEGENERATIVE DISEASE 2012; 1:75-87. [PMID: 22822474 PMCID: PMC3560454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 04/22/2012] [Indexed: 06/01/2023]
Abstract
The amyloid β precursor protein (APP) is a single-pass transmembrane glycoprotein that is ubiquitously expressed in many cell types, including neurons. Amyloidogenic processing of APP by β- and γ-secretases leads to the production of amyloid-β (Aβ) peptides that can oligomerize and aggregate into amyloid plaques, a characteristic hallmark of Alzheimer's disease (AD) brains. Multiple reports suggest that dimerization of APP may play a role in Aβ production; however, it is not yet clear whether APP dimers increase or decrease Aβ and the mechanism is not fully understood. To better understand the relationship between APP dimerization and production of Aβ, a high throughput screen for small molecule modulators of APP dimerization was conducted using APP-Firefly luciferase enzyme complementation to detect APP dimerization. Selected modulators identified from a compound library of 77,440 compounds were tested for their effects on Aβ generation. Two molecules that inhibited APP dimerization produced a reduction in Aβ levels as measured by ELISA. The inhibitors did not change sAPPα or γ-CTF levels, but lowered sAPPβ levels, suggesting that blocking the dimerization is preventing the cleavage by β-secretase in the amyloidogenic processing of APP. To our knowledge, this is the first High Throughput Screen (HTS) effort to identify small molecule modulators of APP dimerization. Inhibition of APP dimerization has previously been suggested as a therapeutic target in AD. The findings reported here further support that modulation of APP dimerization may be a viable means of reducing the production of Aβ.
Collapse
Affiliation(s)
- Pauline Pl So
- Department of Medicine Graduate Program in Molecular Medicine, Boston University School of Medicine, Boston, MA, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Crump CJ, Fish BA, Castro SV, Chau DM, Gertsik N, Ahn K, Stiff C, Pozdnyakov N, Bales KR, Johnson DS, Li YM. Piperidine acetic acid based γ-secretase modulators directly bind to Presenilin-1. ACS Chem Neurosci 2011; 2:705-710. [PMID: 22229075 DOI: 10.1021/cn200098p] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Aβ42 is believed to play a causative role in Alzheimer's disease (AD) pathogenesis. γ-Secretase modulators (GSMs) are actively being pursued as potential AD therapeutics because they selectively alter the cleavage site of the amyloid precursor protein (APP) to reduce the formation of Aβ42. However, the binding partner of acid based GSMs was unresolved until now. We have developed clickable photoaffinity probes based on piperidine acetic acid GSM-1 and identified PS1 as the target within the γ-secretase complex. Furthermore, we provide evidence that allosteric interaction of GSMs with PS1 results in a conformational change in the active site of the γ-secretase complex leading to the observed modulation of γ-secretase activity.
Collapse
Affiliation(s)
- Christina J. Crump
- Molecular Pharmacology
and Chemistry
Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Benjamin A. Fish
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340,
United States
| | - Suita V. Castro
- Molecular Pharmacology
and Chemistry
Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - De-Ming Chau
- Molecular Pharmacology
and Chemistry
Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Natalya Gertsik
- Molecular Pharmacology
and Chemistry
Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Kwangwook Ahn
- Molecular Pharmacology
and Chemistry
Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Cory Stiff
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340,
United States
| | - Nikolay Pozdnyakov
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340,
United States
| | - Kelly R. Bales
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340,
United States
| | - Douglas S. Johnson
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340,
United States
| | - Yue-Ming Li
- Molecular Pharmacology
and Chemistry
Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| |
Collapse
|
50
|
Kukar TL, Ladd TB, Robertson P, Pintchovski SA, Moore B, Bann MA, Ren Z, Jansen-West K, Malphrus K, Eggert S, Maruyama H, Cottrell BA, Das P, Basi GS, Koo EH, Golde TE. Lysine 624 of the amyloid precursor protein (APP) is a critical determinant of amyloid β peptide length: support for a sequential model of γ-secretase intramembrane proteolysis and regulation by the amyloid β precursor protein (APP) juxtamembrane region. J Biol Chem 2011; 286:39804-12. [PMID: 21868378 PMCID: PMC3220543 DOI: 10.1074/jbc.m111.274696] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 08/16/2011] [Indexed: 11/06/2022] Open
Abstract
γ-Secretase is a multiprotein intramembrane cleaving aspartyl protease (I-CLiP) that catalyzes the final cleavage of the amyloid β precursor protein (APP) to release the amyloid β peptide (Aβ). Aβ is the primary component of senile plaques in Alzheimer's disease (AD), and its mechanism of production has been studied intensely. γ-Secretase executes multiple cleavages within the transmembrane domain of APP, with cleavages producing Aβ and the APP intracellular domain (AICD), referred to as γ and ε, respectively. The heterogeneous nature of the γ cleavage that produces various Aβ peptides is highly relevant to AD, as increased production of Aβ 1-42 is genetically and biochemically linked to the development of AD. We have identified an amino acid in the juxtamembrane region of APP, lysine 624, on the basis of APP695 numbering (position 28 relative to Aβ) that plays a critical role in determining the final length of Aβ peptides released by γ-secretase. Mutation of this lysine to alanine (K28A) shifts the primary site of γ-secretase cleavage from 1-40 to 1-33 without significant changes to ε cleavage. These results further support a model where ε cleavage occurs first, followed by sequential proteolysis of the remaining transmembrane fragment, but extend these observations by demonstrating that charged residues at the luminal boundary of the APP transmembrane domain limit processivity of γ-secretase.
Collapse
Affiliation(s)
- Thomas L Kukar
- Emory University, School of Medicine, Department of Pharmacology, Center for Neurodegenerative Disease, Atlanta, Georgia 30322, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|