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Wouters Y, Jaspers T, De Strooper B, Dewilde M. Identification and in vivo characterization of a brain-penetrating nanobody. Fluids Barriers CNS 2020; 17:62. [PMID: 33054787 PMCID: PMC7556960 DOI: 10.1186/s12987-020-00226-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/08/2020] [Indexed: 12/11/2022] Open
Abstract
Background Preclinical models to determine blood to brain transport ability of therapeutics are often ambiguous. In this study a method is developed that relies on CNS target-engagement and is able to rank brain-penetrating capacities. This method led to the discovery of an anti-transferrin receptor nanobody that is able to deliver a biologically active peptide to the brain via receptor-mediated transcytosis. Methods Various nanobodies against the mouse transferrin receptor were fused to neurotensin and injected peripherally in mice. Neurotensin is a neuropeptide that causes hypothermia when present in the brain but is unable to reach the brain from the periphery. Continuous body temperature measurements were used as a readout for brain penetration of nanobody-neurotensin fusions after its peripheral administration. Full temperature curves were analyzed using two-way ANOVA with Dunnett multiple comparisons tests. Results One anti-transferrin receptor nanobody coupled to neurotensin elicited a drop in body temperature following intravenous injection. Epitope binning indicated that this nanobody bound a distinct transferrin receptor epitope compared to the non-crossing nanobodies. This brain-penetrating nanobody was used to characterize the in vivo hypothermia model. The hypothermic effect caused by neurotensin is dose-dependent and could be used to directly compare peripheral administration routes and various nanobodies in terms of brain exposure. Conclusion This method led to the discovery of an anti-transferrin receptor nanobody that can reach the brain via receptor-mediated transcytosis after peripheral administration. This method could be used to assess novel proteins for brain-penetrating capabilities using a target-engaging readout.
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Affiliation(s)
- Y Wouters
- VIB Center for Brain & Disease Research, Campus Gasthuisberg O&N4, Herestraat 49, box 602, B-3000, Leuven, Belgium.,Laboratory for the Research of Neurodegenerative Diseases, Department of Neurosciences, Leuven Brain Institute (LBI), KU Leuven, B-3000, Leuven, Belgium
| | - T Jaspers
- VIB Center for Brain & Disease Research, Campus Gasthuisberg O&N4, Herestraat 49, box 602, B-3000, Leuven, Belgium.,Laboratory for the Research of Neurodegenerative Diseases, Department of Neurosciences, Leuven Brain Institute (LBI), KU Leuven, B-3000, Leuven, Belgium
| | - B De Strooper
- VIB Center for Brain & Disease Research, Campus Gasthuisberg O&N4, Herestraat 49, box 602, B-3000, Leuven, Belgium. .,Laboratory for the Research of Neurodegenerative Diseases, Department of Neurosciences, Leuven Brain Institute (LBI), KU Leuven, B-3000, Leuven, Belgium. .,UK Dementia Research Institute, University College London, London, UK.
| | - M Dewilde
- VIB Center for Brain & Disease Research, Campus Gasthuisberg O&N4, Herestraat 49, box 602, B-3000, Leuven, Belgium. .,Laboratory for the Research of Neurodegenerative Diseases, Department of Neurosciences, Leuven Brain Institute (LBI), KU Leuven, B-3000, Leuven, Belgium. .,VIB Discovery Sciences, B-3000, Leuven, Belgium. .,Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, B-3000, Leuven, Belgium.
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Veugelen S, Dewilde M, De Strooper B, Chávez-Gutiérrez L. Screening and Characterization Strategies for Nanobodies Targeting Membrane Proteins. Methods Enzymol 2016; 584:59-97. [PMID: 28065273 DOI: 10.1016/bs.mie.2016.10.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
The study of membrane protein function and structure requires their successful detection, expression, solubilization, and/or reconstitution, which poses a challenging task and relies on the availability of suitable tools. Several research groups have successfully applied Nanobodies in the purification, as well as the functional and structural characterization of membrane proteins. Nanobodies are small, single-chain antibody fragments originating from camelids presenting on average a longer CDR3 which enables them to bind in cavities and clefts (such as active and allosteric sites). Notably, Nanobodies generally bind conformational epitopes making them very interesting tools to stabilize, dissect, and characterize specific protein conformations. In the clinic, several Nanobodies are under evaluation either as potential drug candidates or as diagnostic tools. In recent years, we have successfully generated high-affinity, conformation-sensitive anti-γ-secretase Nanobodies. γ-Secretase is a multimeric membrane protease involved in processing of the amyloid precursor protein with high clinical relevance as mutations in its catalytic subunit (Presenilin) cause early-onset Alzheimer's disease. Advancing our knowledge on the mechanisms governing γ-secretase intramembrane proteolysis through various strategies may lead to novel therapeutic avenues for Alzheimer's disease. In this chapter, we present the strategies we have developed and applied for the screening and characterization of anti-γ-secretase Nanobodies. These protocols could be of help in the generation of Nanobodies targeting other membrane proteins.
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Affiliation(s)
- S Veugelen
- University of Leuven, Leuven, Belgium; VIB Center for Brain and Disease, Leuven, Belgium
| | - M Dewilde
- University of Leuven, Leuven, Belgium; VIB Center for Brain and Disease, Leuven, Belgium
| | - B De Strooper
- University of Leuven, Leuven, Belgium; VIB Center for Brain and Disease, Leuven, Belgium; UCL Institute of Neurology, London, United Kingdom
| | - L Chávez-Gutiérrez
- University of Leuven, Leuven, Belgium; VIB Center for Brain and Disease, Leuven, Belgium.
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3
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Sala Frigerio C, Lau P, Salta E, Tournoy J, Bossers K, Vandenberghe R, Wallin A, Bjerke M, Zetterberg H, Blennow K, De Strooper B. Reduced expression of hsa-miR-27a-3p in CSF of patients with Alzheimer disease. Neurology 2013; 81:2103-6. [DOI: 10.1212/01.wnl.0000437306.37850.22] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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4
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Mandemakers W, Abuhatzira L, Xu H, Caromile LA, Hébert SS, Snellinx A, Morais VA, Matta S, Cai T, Notkins AL, De Strooper B. Co-regulation of intragenic microRNA miR-153 and its host gene Ia-2 β: identification of miR-153 target genes with functions related to IA-2β in pancreas and brain. Diabetologia 2013; 56:1547-56. [PMID: 23595248 PMCID: PMC3671108 DOI: 10.1007/s00125-013-2901-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 02/26/2013] [Indexed: 01/01/2023]
Abstract
AIMS/HYPOTHESIS We analysed the genomic organisation of miR-153, a microRNA embedded in genes that encode two of the major type 1 diabetes autoantigens, islet-associated protein (IA)-2 and IA-2β. We also identified miR-153 target genes that correlated with IA-2β localisation and function. METHODS A bioinformatics approach was used to identify miR-153's genomic organisation. To analyse the co-regulation of miR-153 and IA-2β, quantitative PCR analysis of miR-153 and Ia-2β (also known as Ptprn2) was performed after a glucose stimulation assay in MIN6B cells and isolated murine pancreatic islets, and also in wild-type Ia-2 (also known as Ptprn), Ia-2β single knockout and Ia-2/Ia-2β double knockout mouse brain and pancreatic islets. Bioinformatics identification of miR-153 target genes and validation via luciferase reporter assays, western blotting and quantitative PCR were also carried out. RESULTS Two copies of miR-153, miR-153-1 and miR-153-2, are localised in intron 19 of Ia-2 and Ia-2β, respectively. In rodents, only miR-153-2 is conserved. We demonstrated that expression of miR-153-2 and Ia-2β in rodents is partially co-regulated as demonstrated by a strong reduction of miR-153 expression levels in Ia-2β knockout and Ia-2/Ia-2β double knockout mice. miR-153 levels were unaffected in Ia-2 knockout mice. In addition, glucose stimulation, which increases Ia-2 and Ia-2β expression, also significantly increased expression of miR-153. Several predicted targets of miR-153 were reduced after glucose stimulation in vitro, correlating with the increase in miR-153 levels. CONCLUSIONS/INTERPRETATION This study suggests the involvement of miR-153, IA-2β and miR-153 target genes in a regulatory network, which is potentially relevant to insulin and neurotransmitter release.
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Affiliation(s)
- W. Mandemakers
- VIB Center for the Biology of Disease, Gasthuisberg O&N4, Herestraat 49-bus 602, 3000 Leuven, Belgium
- Center for Human Genetics, LIND and Universitaire Ziekenhuizen, KULeuven, Leuven, Belgium
| | - L. Abuhatzira
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD USA
| | - H. Xu
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD USA
| | - L. A. Caromile
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD USA
| | - S. S. Hébert
- VIB Center for the Biology of Disease, Gasthuisberg O&N4, Herestraat 49-bus 602, 3000 Leuven, Belgium
- Center for Human Genetics, LIND and Universitaire Ziekenhuizen, KULeuven, Leuven, Belgium
- Present Address: Neurosciences, Centre de Recherche du CHUQ (CHUL), RC-9800, 2705 boul. Laurier, Québec, QC Canada
| | - A. Snellinx
- VIB Center for the Biology of Disease, Gasthuisberg O&N4, Herestraat 49-bus 602, 3000 Leuven, Belgium
- Center for Human Genetics, LIND and Universitaire Ziekenhuizen, KULeuven, Leuven, Belgium
| | - V. A. Morais
- VIB Center for the Biology of Disease, Gasthuisberg O&N4, Herestraat 49-bus 602, 3000 Leuven, Belgium
- Center for Human Genetics, LIND and Universitaire Ziekenhuizen, KULeuven, Leuven, Belgium
| | - S. Matta
- VIB Center for the Biology of Disease, Gasthuisberg O&N4, Herestraat 49-bus 602, 3000 Leuven, Belgium
- Center for Human Genetics, LIND and Universitaire Ziekenhuizen, KULeuven, Leuven, Belgium
| | - T. Cai
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD USA
| | - A. L. Notkins
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD USA
| | - B. De Strooper
- VIB Center for the Biology of Disease, Gasthuisberg O&N4, Herestraat 49-bus 602, 3000 Leuven, Belgium
- Center for Human Genetics, LIND and Universitaire Ziekenhuizen, KULeuven, Leuven, Belgium
- Center for Human Genetics-CB4, VIB Center for the Biology of Disease–VIB11, Gasthuisberg O&N4, Herestraat 49-bus 602, 3000 Leuven, Belgium
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Garratt A, Willem M, Saftig P, De Strooper B, Birchmeier C, Haass C. [P76]: Functions of the protease bace1 in the maturation of the nervous system. Int J Dev Neurosci 2006. [DOI: 10.1016/j.ijdevneu.2006.09.138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- A. Garratt
- Max‐Delbrueck‐Center for Molecular MedicineGermany
| | - M. Willem
- Ludwig‐Maximilians‐University of MunichGermany
| | - P. Saftig
- Christian Albrecht University KielGermany
| | | | | | - C. Haass
- Ludwig‐Maximilians‐University of MunichGermany
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Theuns J, Marjaux E, Vandenbulcke M, Van Laere K, Kumar-Singh S, Bormans G, Brouwers N, Van den Broeck M, Vennekens K, Corsmit E, Cruts M, De Strooper B, Van Broeckhoven C, Vandenberghe R. Alzheimer dementia caused by a novel mutation located in the APP C-terminal intracytosolic fragment. Hum Mutat 2006; 27:888-96. [PMID: 16917905 DOI: 10.1002/humu.20402] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Since the first report showing that Alzheimer disease (AD) might be caused by mutations in the amyloid precursor protein gene (APP), 20 different missense mutations have been reported. The majority of early-onset AD mutations alter processing of APP increasing relative levels of Abeta42 peptide, either by increasing Abeta42 or decreasing Abeta40 peptide levels or both. In a diagnostic setting using direct sequence analysis, we identified in one patient with familial early-onset AD a novel mutation in APP (c.2172G>C), predicting a K724N substitution in the intracytosolic fragment. The mutation is located downstream of the epsilon-cleavage site of APP and is the furthermost C-terminal mutation reported to date. In vitro expression of APP K724N cDNA showed an increase in Abeta42 and a decrease in Abeta40 levels resulting in a near three-fold increase of the Abeta42/Abeta40 ratio. Further, in vivo amyloid positron emission tomography (PET) imaging revealed significantly increased cortical amyloid deposits, supporting that in human this novel APP mutation is likely causing disease.
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Affiliation(s)
- J Theuns
- Neurodegenerative Brain Diseases Group, Department of Molecular Genetics, Flanders Interuniversity Institute for Biotechnology, Belgium
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8
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Annaert WG, Esselens C, Baert V, Boeve C, Snellings G, Cupers P, Craessaerts K, De Strooper B. Interaction with telencephalin and the amyloid precursor protein predicts a ring structure for presenilins. Neuron 2001; 32:579-89. [PMID: 11719200 DOI: 10.1016/s0896-6273(01)00512-8] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The carboxyl terminus of presenilin 1 and 2 (PS1 and PS2) binds to the neuron-specific cell adhesion molecule telencephalin (TLN) in the brain. PS1 deficiency results in the abnormal accumulation of TLN in a yet unidentified intracellular compartment. The first transmembrane domain and carboxyl terminus of PS1 form a binding pocket with the transmembrane domain of TLN. Remarkably, APP binds to the same regions via part of its transmembrane domain encompassing the critical residues mutated in familial Alzheimer's disease. Our data surprisingly indicate a spatial dissociation between the binding site and the proposed catalytic site near the critical aspartates in PSs. They provide important experimental evidence to support a ring structure model for PS.
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Affiliation(s)
- W G Annaert
- Laboratory for Neuronal Cell Biology, Department of Human Genetics, Flanders Interuniversity Institute for Biotechnology, KUL-Gasthuisberg, B-3000 Leuven, Belgium.
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9
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Wiltfang J, Esselmann H, Cupers P, Neumann M, Kretzschmar H, Beyermann M, Schleuder D, Jahn H, Rüther E, Kornhuber J, Annaert W, De Strooper B, Saftig P. Elevation of beta-amyloid peptide 2-42 in sporadic and familial Alzheimer's disease and its generation in PS1 knockout cells. J Biol Chem 2001; 276:42645-57. [PMID: 11526104 DOI: 10.1074/jbc.m102790200] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Urea-based beta-amyloid (Abeta) SDS-polyacrylamide gel electrophoresis and immunoblots were used to analyze the generation of Abeta peptides in conditioned medium from primary mouse neurons and a neuroglioma cell line, as well as in human cerebrospinal fluid. A comparable and highly conserved pattern of Abeta peptides, namely, 1-40/42 and carboxyl-terminal-truncated 1-37, 1-38, and 1-39, was found. Besides Abeta1-42, we also observed a consistent elevation of amino-terminal-truncated Abeta2-42 in a detergent-soluble pool in brains of subjects with Alzheimer's disease. Abeta2-42 was also specifically elevated in cerebrospinal fluid samples of Alzheimer's disease patients. To decipher the contribution of potential different gamma-secretases (presenilins (PSs)) in generating the amino-terminal- and carboxyl-terminal-truncated Abeta peptides, we overexpressed beta-amyloid precursor protein (APP)-trafficking mutants in PS1+/+ and PS1-/- neurons. As compared with APP-WT (primary neurons from control or PS1-deficient mice infected with Semliki Forest virus), PS1-/- neurons and PS1+/+ neurons overexpressing APP-Deltact (a slow-internalizing mutant) show a decrease of all secreted Abeta peptide species, as expected, because this mutant is processed mainly by alpha-secretase. This drop is even more pronounced for the APP-KK construct (APP mutant carrying an endoplasmic reticulum retention motif). Surprisingly, Abeta2-42 is significantly less affected in PS1-/- neurons and in neurons transfected with the endocytosis-deficient APP-Deltact construct. Our data confirm that PS1 is closely involved in the production of Abeta1-40/42 and the carboxyl-terminal-truncated Abeta1-37, Abeta1-38, and Abeta1-39, but the amino-terminal-truncated and carboxyl-terminal-elongated Abeta2-42 seems to be less affected by PS1 deficiency. Moreover, our results indicate that the latter Abeta peptide species could be generated by a beta(Asp/Ala)-secretase activity.
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MESH Headings
- Aged
- Aged, 80 and over
- Alzheimer Disease/cerebrospinal fluid
- Alzheimer Disease/metabolism
- Amino Acid Sequence
- Amyloid Precursor Protein Secretases
- Amyloid beta-Peptides/biosynthesis
- Amyloid beta-Peptides/cerebrospinal fluid
- Amyloid beta-Peptides/chemistry
- Animals
- Aspartic Acid Endopeptidases/metabolism
- Brain/metabolism
- Cell Line
- Cells, Cultured
- DNA, Complementary/metabolism
- Electrophoresis, Gel, Two-Dimensional
- Electrophoresis, Polyacrylamide Gel
- Endopeptidases
- Endoplasmic Reticulum/metabolism
- Humans
- Immunoblotting
- Mice
- Mice, Knockout
- Middle Aged
- Molecular Sequence Data
- Mutation
- Neurons/metabolism
- Peptide Fragments/biosynthesis
- Peptide Fragments/cerebrospinal fluid
- Peptide Fragments/chemistry
- Peptides/chemistry
- Precipitin Tests
- Protein Binding
- Protein Structure, Tertiary
- Semliki forest virus/genetics
- Sequence Homology, Amino Acid
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
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Affiliation(s)
- J Wiltfang
- Department of Psychiatry, Molecular Neurobiology, and Department of Biochemistry II, University of Göttingen, D-37073 Göttingen, Germany.
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11
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Abstract
It is widely believed that the pathogenesis of Alzheimer's disease (AD) is intimately, if not causatively, associated with the deposition of approximately 4 kDa beta-amyloid (A beta) peptides in the cerebral cortex and hippocampus of affected individuals. A beta peptides are liberated from transmembrane proteins, termed beta-amyloid precursor proteins (APP), by the concerted action of beta- and gamma-secretase(s). Whereas the identity of beta-secretase is no longer in question, the identity of gamma-secretase, which is responsible for the intramembranous processing of APP, has never been more enigmatic. Considerable evidence has accrued to impugn the presenilins (PS) as the executioners of intramembranous processing of APP. Here, we summarize these observations and review recent evidence that argues against the prevailing hypothesis that PS function as gamma-secretases.
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Affiliation(s)
- S S Sisodia
- Center for Molecular Neurobiology, Dept of Neurobiology, Pharmacology and Physiology, The University of Chicago, IL 60637, USA.
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12
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Vincent B, Paitel E, Saftig P, Frobert Y, Hartmann D, De Strooper B, Grassi J, Lopez-Perez E, Checler F. The disintegrins ADAM10 and TACE contribute to the constitutive and phorbol ester-regulated normal cleavage of the cellular prion protein. J Biol Chem 2001; 276:37743-6. [PMID: 11477090 DOI: 10.1074/jbc.m105677200] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We showed previously that PrPc undergoes constitutive and phorbol ester-regulated cleavage inside the 106-126 toxic domain of the protein, leading to the production of a fragment referred to as N1. Here we show by a pharmacological approach that o-phenanthroline, a general zinc-metalloprotease inhibitors, as well as BB3103 and TAPI, the inhibitors of metalloenzymes ADAM10 (A disintegrin and metalloprotease); and TACE, tumor necrosis factor alpha-converting enzyme; ADAM17), respectively, drastically reduce N1 formation. We set up stable human embryonic kidney 293 transfectants overexpressing human ADAM10 and TACE, and we demonstrate that ADAM10 contributes to constitutive N1 production whereas TACE mainly participates in regulated N1 formation. Furthermore, constitutive N1 secretion is drastically reduced in fibroblasts deficient for ADAM10 whereas phorbol 12,13-dibutyrate-regulated N1 production is fully abolished in TACE-deficient cells. Altogether, our data demonstrate for the first time that disintegrins could participate in the catabolism of glycosyl phosphoinositide-anchored proteins such as PrPc. Second, our study identifies ADAM10 and ADAM17 as the protease candidates responsible for normal cleavage of PrPc. Therefore, these disintegrins could be seen as putative cellular targets of a therapeutic strategy aimed at increasing normal PrPc breakdown and thereby depleting cells of the putative 106-126 "toxic" domain of PrPc.
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Affiliation(s)
- B Vincent
- Institut de Pharmacologie Moléculaire et Cellulaire du CNRS, UMR6097, 06560 Valbonne, France
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13
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Abstract
Signaling via notch receptors and their ligands is an evolutionary ancient and highly conserved mechanism governing cell-fate decisions throughout the animal kingdom. Upon ligand binding, notch receptors are subject to a two-step proteolysis essential for signal transduction. First, the ectodomain is removed by an enzyme cleaving near the outer-membrane surface ("site2"). Consecutively, the notch intracellular domain is liberated by a second protease cutting within the transmembrane sequence ("site3"). The intracellular domain is then transferred to the nucleus to act as a transcriptional coactivator. The proteases involved in notch receptor activation are shared with other proteins undergoing regulated intramembrane proteolysis, with intriguing parallels to APP. Specifically, site3 cleavage of Notch, as well as gamma-secretase processing of APP depend both critically on presenilins 1 and 2. Moreover, ADAM 10 and ADAM 17, the proteases proposed to perform site2 cleavage, are also the most probable candidate alpha-secretases to cleave APP. While the biological significance of APP processing remains to be further elucidated, interference with notch signaling has been shown to have severe consequences both in small animal models as well as in humans. Thus, a growing number of long known genetic syndromes like Alagille syndrome or Fallot's tetralogy can be caused by mutations of genes relevant for the notch signaling pathway. Likewise, the anticipated interference of gamma-secretase inhibitors with site3 cleavage may turn out to be a major obstacle for this therapeutic approach to Alzheimer's disease.
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Affiliation(s)
- D Hartmann
- Center for Human Genetics, Neuronal Cell Biology Laboratory, K.U.Leuven and Flanders Interuniversity Institute for Biotechnology, Leuven, Belgium
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14
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Affiliation(s)
- B D Strooper
- Center for Human Genetics, Neuronal Cell Biology Laboratory, The K.U. Leuven and Flanders Interuniversity Institute for Biotechnology, Herestraat 49 3000 Leuven, Belgium.
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15
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Cupers P, Orlans I, Craessaerts K, Annaert W, De Strooper B. The amyloid precursor protein (APP)-cytoplasmic fragment generated by gamma-secretase is rapidly degraded but distributes partially in a nuclear fraction of neurones in culture. J Neurochem 2001; 78:1168-78. [PMID: 11553691 DOI: 10.1046/j.1471-4159.2001.00516.x] [Citation(s) in RCA: 203] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The gamma-secretase cleavage is the last step in the generation of the beta-amyloid peptide (Abeta) from the amyloid precursor protein (APP). The Abeta precipitates in the amyloid plaques in the brain of Alzheimer's disease patients. The fate of the intracellular APP carboxy-terminal stub generated together with Abeta has been, in contrast, only poorly documented. The analogies between the processing of APP and other transmembrane proteins like SREBP and Notch suggests that this intracellular fragment could have important signalling functions. We demonstrate here that APP-C59 is rapidly degraded (half-life approximately 5 min) when overexpressed in baby hamster kidney cells or primary cultures of neurones by a mechanism that is not inhibited by endosomal/lysosomal or proteasome inhibitors. Furthermore, APP-C59 binds to the DNA binding protein Fe65, although this does not increase the half-life of APP-C59. Finally, we demonstrate that a fraction of APP-C59 becomes redistributed to the nuclear detergent-insoluble pellet, in which the transcription factor SP1 is also present. Overall our results reinforce the analogy between Notch and APP processing, and suggest that the APP intracellular domain, like the Notch intracellular domain, could have a role in signalling events from the plasma membrane to the nucleus.
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Affiliation(s)
- P Cupers
- Neuronal Cell Biology Group, Center for Human Genetics, Flanders Interuniversitary Institute for Biotechnology and Catholic University of Leuven, Leuven, Belgium
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16
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Tomita T, Watabiki T, Takikawa R, Morohashi Y, Takasugi N, Kopan R, De Strooper B, Iwatsubo T. The first proline of PALP motif at the C terminus of presenilins is obligatory for stabilization, complex formation, and gamma-secretase activities of presenilins. J Biol Chem 2001; 276:33273-81. [PMID: 11432849 DOI: 10.1074/jbc.m011152200] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in presenilin (PS) genes cause early-onset familial Alzheimer's disease by increasing production of the amyloidogenic form of amyloid beta peptides ending at residue 42 (Abeta42). PS is an evolutionarily conserved multipass transmembrane protein, and all known PS proteins contain a proline-alanine-leucine-proline (PALP) motif starting at proline (P) 414 (amino acid numbering based on human PS2) at the C terminus. Furthermore, missense mutations that replace the first proline of PALP with leucine (P414L) lead to a loss-of-function of PS in Drosophila melanogaster and Caenorhabditis elegans. To elucidate the roles of the PALP motif in PS structure and function, we analyzed neuro2a as well as PS1/2 null fibroblast cell lines transfected with human PS harboring mutations at the PALP motif. P414L mutation in PS2 (and its equivalent in PS1) abrogated stabilization, high molecular weight complex formation, and entry to Golgi/trans-Golgi network of PS proteins, resulting in failure of Abeta42 overproduction on familial Alzheimer's disease mutant basis as well as of site-3 cleavage of Notch. These data suggest that the first proline of the PALP motif plays a crucial role in the stabilization and formation of the high molecular weight complex of PS, the latter being the active form with intramembrane proteolytic activities.
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Affiliation(s)
- T Tomita
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Cupers P, Bentahir M, Craessaerts K, Orlans I, Vanderstichele H, Saftig P, De Strooper B, Annaert W. The discrepancy between presenilin subcellular localization and gamma-secretase processing of amyloid precursor protein. J Cell Biol 2001; 154:731-40. [PMID: 11502763 PMCID: PMC2196466 DOI: 10.1083/jcb.200104045] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the relationship between PS1 and gamma-secretase processing of amyloid precursor protein (APP) in primary cultures of neurons. Increasing the amount of APP at the cell surface or towards endosomes did not significantly affect PS1-dependent gamma-secretase cleavage, although little PS1 is present in those subcellular compartments. In contrast, almost no gamma-secretase processing was observed when holo-APP or APP-C99, a direct substrate for gamma-secretase, were specifically retained in the endoplasmic reticulum (ER) by a double lysine retention motif. Nevertheless, APP-C99-dilysine (KK) colocalized with PS1 in the ER. In contrast, APP-C99 did not colocalize with PS1, but was efficiently processed by PS1-dependent gamma-secretase. APP-C99 resides in a compartment that is negative for ER, intermediate compartment, and Golgi marker proteins. We conclude that gamma-secretase cleavage of APP-C99 occurs in a specialized subcellular compartment where little or no PS1 is detected. This suggests that at least one other factor than PS1, located downstream of the ER, is required for the gamma-cleavage of APP-C99. In agreement, we found that intracellular gamma-secretase processing of APP-C99-KK both at the gamma40 and the gamma42 site could be restored partially after brefeldin A treatment. Our data confirm the "spatial paradox" and raise several questions regarding the PS1 is gamma-secretase hypothesis.
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Affiliation(s)
- P Cupers
- Center for Human Genetics, Neuronal Cell Biology Group, Flanders Interuniversity Institute for Biotechnology and Catholic University of Leuven, B-3000 Leuven, Belgium
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18
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De Jonghe C, Esselens C, Kumar-Singh S, Craessaerts K, Serneels S, Checler F, Annaert W, Van Broeckhoven C, De Strooper B. Pathogenic APP mutations near the gamma-secretase cleavage site differentially affect Abeta secretion and APP C-terminal fragment stability. Hum Mol Genet 2001; 10:1665-71. [PMID: 11487570 DOI: 10.1093/hmg/10.16.1665] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Release of amyloid beta (Abeta) from the amyloid precursor protein (APP) requires cleavages by beta- and gamma-secretases and plays a crucial role in Alzheimer's disease (AD) pathogenesis. Missense mutations in the APP gene causing familial AD are clustered around the beta-, alpha- and particular gamma-secretase cleavage sites. We systematically compare in primary neurons the effect on APP processing of a series of clinical APP mutations (two of which not characterized before) located in close proximity to the gamma-secretase cleavage site. We confirm and extend previous observations showing that all these mutations (T714I, V715M, V715A, I716V, V717I and V717L) affect gamma-secretase cleavage causing an increased relative ratio of Abeta42 to Abeta40. Taking advantage of these extended series of APP mutations we were able to demonstrate an inverse correlation between these ratios and the age at onset of the disease in the different families. In addition, a subset of mutations caused the accumulation of APP C-terminal fragments indicating that these mutations also influence the stability of APP C-terminal fragments. However, it is unlikely that these fragments contribute significantly to the disease process.
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Affiliation(s)
- C De Jonghe
- Laboratory of Neurogenetics, Department of Molecular Genetics, Flanders Interuniversity Institute for Biotechnology, University of Antwerp, Belgium
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19
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Abstract
The extracellular deposition of short amyloid peptides in the brain of patients is thought to be a central event in the pathogenesis of Alzheimer's Disease. The generation of the amyloid peptide occurs via a regulated cascade of cleavage events in its precursor protein, A beta PP. At least three enzymes are responsible for A beta PP proteolysis and have been tentatively named alpha-, beta- and gamma-secretases. The recent identification of several of these secretases is a major leap in the understanding how these secretases regulate amyloid peptide formation. Members of the ADAM family of metalloproteases are involved in the non-amyloidogenic alpha-secretase pathway. The amyloidogenic counterpart pathway is initiated by the recently cloned novel aspartate protease named BACE. The available data are conclusive and crown BACE as the long-sought beta-secretase. This enzyme is a prime candidate drug target for the development of therapy aiming to lower the amyloid burden in the disease. Finally, the gamma-secretases are intimately linked to the function of the presenilins. These multi-transmembrane domain proteins remain intriguing study objects. The hypothesis that the presenilins constitute a complete novel type of protease family, and are cleaving A beta PP within the transmembrane region, remains an issue of debate. Several questions remain unanswered and direct proof that they exert catalytic activity is still lacking. The subcellular localization of presenilins in neurons, their integration in functional multiprotein complexes and the recent identification of additional modulators of gamma-secretase, like nicastrin, indicate already that several players are involved. Nevertheless, the rapidly increasing knowledge in this area is already paving the road towards selective inhibitors of this secretase as well. It is hoped that such drugs, possibly in concert with the experimental vaccination therapies that are currently tested, will lead to a cure of this inexorable disease.
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Affiliation(s)
- D I Dominguez
- Flanders Interuniversitary Institute for Biotechnology and K.U. Leuven, Neuronal Cell Biology and Gene Transfer Laboratory, Center for Human Genetics, Gasthuisberg, B-3000 Leuven, Belgium
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20
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Abstract
Familial Alzheimer's disease (FAD) is now linked to at least three genes encoding the amyloid precursor protein (APP) on chromosome 21, and presenilin 1 and 2 on chromosome 14 and 1, respectively. FAD cases in whom presenilin mutations occur are more frequent than those with APP mutations. However, altogether they only account for approximately 0.1% of all the people suffering from Alzheimer's disease (AD), and the causes of the remaining 99.9% of the sporadic form of AD or senile dementia remain unknown. Since FAD presents with the same neuropathological features as sporadic AD, i.e., cognitive impairments and the amyloid plaques and tangles in the brain, our working hypothesis is that similar molecular pathogenic mechanisms underly both sporadic and familial AD. It follows that APP and the presenilins must be key players in the disease. Detailed knowledge about the cell biology of these proteins will be a rich source of insight into the pathology of AD, but will also shed light on the fundamental neurobiology of these proteins.
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Affiliation(s)
- W Annaert
- Center for Human Genetics, Flanders Interuniversitary Institute for Biotechnology, Gasthuisberg, KULeuven, Leuven, Belgium
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21
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Affiliation(s)
- B De Strooper
- Center for Human Genetics, Neuronal Cell Biology Laboratory, Katholieke Universiteit Leuven and Flanders Interuniversitary Institute for Biotechnology, 3000 Leuven, Belgium.
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22
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Creemers JW, Ines Dominguez D, Plets E, Serneels L, Taylor NA, Multhaup G, Craessaerts K, Annaert W, De Strooper B. Processing of beta-secretase by furin and other members of the proprotein convertase family. J Biol Chem 2001; 276:4211-7. [PMID: 11071887 DOI: 10.1074/jbc.m006947200] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The amyloid peptide is the main constituent of the amyloid plaques in brain of Alzheimer's disease patients. This peptide is generated from the amyloid precursor protein by two consecutive cleavages. Cleavage at the N terminus is performed by the recently discovered beta-secretase (Bace). This aspartyl protease contains a propeptide that has to be removed to obtain mature Bace. Furin and other members of the furin family of prohormone convertases are involved in this process. Surprisingly, beta-secretase activity, neither at the classical Asp(1) position nor at the Glu(11) position of amyloid precursor protein, seems to be controlled by this maturation step. Furthermore, we show that Glu(11) cleavage is a function of the expression level of Bace, that it depends on the membrane anchorage of Bace, and that Asp(1) cleavage can be followed by Glu(11) cleavage. Our data suggest that pro-Bace could be active as a beta-secretase in the early biosynthetic compartments of the cell and could be involved in the generation of the intracellular pool of the amyloid peptide. We conclude that modulation of the conversion of pro-Bace to mature Bace is not a relevant drug target to treat Alzheimer's disease.
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Affiliation(s)
- J W Creemers
- Center for Human Genetics, Molecular Oncology and Neuronal Cell Biology Laboratories, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
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23
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Ledesma MD, Da Silva JS, Crassaerts K, Delacourte A, De Strooper B, Dotti CG. Brain plasmin enhances APP alpha-cleavage and Abeta degradation and is reduced in Alzheimer's disease brains. EMBO Rep 2000; 1:530-5. [PMID: 11263499 PMCID: PMC1083779 DOI: 10.1093/embo-reports/kvd107] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The proteolytic processing of amyloid precursor protein (APP) has been linked to sphingolipid-cholesterol microdomains (rafts). However, the raft proteases that may be involved in APP cleavage have not yet been identified. In this work we present evidence that the protease plasmin is restricted to rafts of cultured hippocampal neurons. We also show that plasmin increases the processing of human APP preferentially at the alpha-cleavage site, and efficiently degrades secreted amyloidogenic and non-amyloidogenic APP fragments. These results suggest that brain plasmin plays a preventive role in APP amyloidogenesis. Consistently, we show that brain tissue from Alzheimer's disease patients contains reduced levels of plasmin, implying that plasmin downregulation may cause amyloid plaque deposition accompanying sporadic Alzheimer's disease.
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Affiliation(s)
- M D Ledesma
- Cell Biology and Biophysics Program, EMBL, Heidelberg, Germany
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24
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Baekelandt V, Claeys A, Cherepanov P, De Clercq E, De Strooper B, Nuttin B, Debyser Z. DNA-Dependent protein kinase is not required for efficient lentivirus integration. J Virol 2000; 74:11278-85. [PMID: 11070027 PMCID: PMC113232 DOI: 10.1128/jvi.74.23.11278-11285.2000] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
How DNA is repaired after retrovirus integration is not well understood. DNA-dependent protein kinase (DNA-PK) is known to play a central role in the repair of double-stranded DNA breaks. Recently, a role for DNA-PK in retroviral DNA integration has been proposed (R. Daniel, R. A. Katz, and A. M. Skalka, Science 284:644-647, 1999). Reduced transduction efficiency and increased cell death by apoptosis were observed upon retrovirus infection of cultured scid cells. We have used a human immunodeficiency virus (HIV) type 1 (HIV-1)-derived lentivirus vector system to further investigate the role of DNA-PK during integration. We measured lentivirus transduction of scid mouse embryonic fibroblasts (MEF) and xrs-5 or xrs-6 cells. These cells are deficient in the catalytic subunit of DNA-PK and in Ku, the DNA-binding subunit of DNA-PK, respectively. At low vector titers, efficient and stable lentivirus transduction was obtained, excluding an essential role for DNA-PK in lentivirus integration. Likewise, the efficiency of transduction of HIV-derived vectors in scid mouse brain was as efficient as that in control mice, without evidence of apoptosis. We observed increased cell death in scid MEF and xrs-5 or xrs-6 cells, but only after transduction with high vector titers (multiplicity of infection [MOI], >1 transducing unit [TU]/cell) and subsequent passage of the transduced cells. At an MOI of <1 TU/cell, however, transduction efficiency was even higher in DNA-PK-deficient cells than in control cells. Taken together, the data suggest a protective role of DNA-PK against cellular toxicity induced by high levels of retrovirus integrase or integration. Another candidate cellular enzyme that has been claimed to play an important role during retrovirus integration is poly(ADP-ribose) polymerase (PARP). However, no inhibition of lentivirus vector-mediated transduction or HIV-1 replication by 3-methoxybenzamide, a known PARP inhibitor, was observed. In conclusion, DNA-PK and PARP are not essential for lentivirus integration.
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Affiliation(s)
- V Baekelandt
- Laboratory for Experimental Neurosurgery and Neuroanatomy, Katholieke Universiteit Leuven, Leuven, Belgium
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25
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Kumar-Singh S, De Jonghe C, Cruts M, Kleinert R, Wang R, Mercken M, De Strooper B, Vanderstichele H, Löfgren A, Vanderhoeven I, Backhovens H, Vanmechelen E, Kroisel PM, Van Broeckhoven C. Nonfibrillar diffuse amyloid deposition due to a gamma(42)-secretase site mutation points to an essential role for N-truncated A beta(42) in Alzheimer's disease. Hum Mol Genet 2000; 9:2589-98. [PMID: 11063718 DOI: 10.1093/hmg/9.18.2589] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Amyloidogenic processing of the amyloid precursor protein (APP) with deposition in brain of the 42 amino acid long amyloid beta-peptide (A beta(42)) is considered central to Alzheimer's disease (AD) pathology. However, it is generally believed that nonfibrillar pre-amyloid A beta(42) deposits have to mature in the presence of A beta(40) into fibrillar amyloid plaques to cause neurodegeneration. Here, we describe an aggressive form of AD caused by a novel missense mutation in APP (T714I) directly involving gamma-secretase cleavages of APP. The mutation had the most drastic effect on A beta(42)/A beta(40) ratio in vitro of approximately 11-fold, simultaneously increasing A beta(42) and decreasing A beta(40) secretion, as measured by matrix-assisted laser disorption ionization time-of-flight mass spectrometry. This coincided in brain with deposition of abundant and predominant nonfibrillar pre-amyloid plaques composed primarily of N-truncated A beta(42) in complete absence of A beta(40). These data indicate that N-truncated A beta(42) as diffuse nonfibrillar plaques has an essential but undermined role in AD pathology. Importantly, inhibiting secretion of full-length A beta(42 )by therapeutic targeting of APP processing should not result in secretion of an equally toxic N-truncated A beta(42).
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Affiliation(s)
- S Kumar-Singh
- Laboratory of Molecular Genetics, Flanders Interuniversity Institute for Biotechnology, Born-Bunge Foundation, University of Antwerp, Universiteitsplein 1, B-2610, Antwerpen, Belgium
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26
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Baekelandt V, De Strooper B, Nuttin B, Debyser Z. Gene therapeutic strategies for neurodegenerative diseases. Curr Opin Mol Ther 2000; 2:540-54. [PMID: 11249757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Gene transfer into the central nervous system by ex vivo or in vivo techniques is a rapidly emerging field in neuroscience. Potential applications of gene therapy for the nervous system include not only congenital single gene disorders, but also brain tumors and acquired chronic diseases. Considerable progress has been made in the understanding of neurodegenerative diseases such as Parkinson's and Alzheimer's disease. As a result, gene therapy for Parkinson's, and possibly Alzheimer's disease could be regarded as a realistic alternative to the limited treatment options currently available. In this review, we highlight the most important developments in gene transfer techniques as well as the newest insights in the mechanisms of some neurodegenerative disorders and put these into the perspective of gene therapeutic strategies for the central nervous system.
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Affiliation(s)
- V Baekelandt
- Laboratory for Experimental Neurosurgery and Neuroanatomy, CEHA Provisorium 1, Minderbroedersstraat 17, B-3000 Leuven, Belgium.
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27
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Affiliation(s)
- W Annaert
- Neuronal Cell Biology and Gene Transfer Laboratory, Centre for Human Genetics, Flanders Interuniversitary Institute for Biotechnology, Gasthuisberg, KU Leuven, Belgium
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28
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Herreman A, Serneels L, Annaert W, Collen D, Schoonjans L, De Strooper B. Total inactivation of gamma-secretase activity in presenilin-deficient embryonic stem cells. Nat Cell Biol 2000; 2:461-2. [PMID: 10878813 DOI: 10.1038/35017105] [Citation(s) in RCA: 416] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- A Herreman
- Neuronal Cell Biology Laboratory, CME, K.U.Leuven and Flanders Interuniversitary Institute for Biotechnology (VIB4), Belgium
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29
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30
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Abstract
Recent research has identified some key players involved in the proteolytic processing of amyloid precursor protein (APP) to amyloid beta-peptide, the principal component of the amyloid plaques in Alzheimer patients. Interesting parallels exists with the proteolysis of other proteins involved in cell differentiation, cholesterol homeostasis and stress responses. Since the cytoplasmic domain of APP is anchored to a complex protein network that might function in axonal elongation, dendritic arborisation and neuronal cell migration, the proteolysis of APP might be critically involved in intracellular signalling events.
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Affiliation(s)
- B De Strooper
- Center for Human Genetics, Flanders interuniversitary institute for Biotechnology and K. U. Leuven, Belgium. bart.destrooper@med. kuleuven.ac.be
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31
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Abstract
Several mutations in genes that cause the familial form of Alzheimer's Disease (FAD) have been identified. All mutations in the three FAD genes, i.e., amyloid precursor protein (APP), presenilin 1 (PS-1), and presenilin 2 (PS-2) cause an increased production of a longer, more amyloidogenic form of the amyloid peptide corroborating strongly the idea that abnormal processing of APP is central to the pathogenesis. In PS-1 deficient mice, 80% less amyloid peptide was produced. Instead, membrane associated carboxyterminal fragments generated by (alpha- and beta-secretase accumulated suggesting that PS-1 is involved in the gamma-secretase activity cleaving the transmembrane domain of APP after alpha- and beta-secretase cleavage has occured. The clinical mutations in PS-1 which increase the production of betaA41-42 therefore seem to cause a "selective" gain of its normal function. During cortical plate development in PS-1-deficient mice, neurons do not terminate their movement at the outer margin of the cortical plate, but enter the marginal zone and subarachnoid space. These focal heterotopias closely resemble those occuring, e.g., in human lissencephaly type II. The extracellular matrix of the cortical plate and marginal zone was altered as a consequence of a loss of Cajal-Retzius (CR) neurons from the marginal zone. The pathogenesis of this neuronal migration disorder is associated with a reduction and redistribution of notch- immunoreactivity in CR- and cortical plate neurons, a cell surface receptor operative in cell fate selection, which similar to APP is cleaved in its transmembrane domain during activation by a gamma-secretase like protease.
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Affiliation(s)
- P Saftig
- Zentrum Biochemie und Molekulare Zellbiologie, Abteilung Biochemie II, Universität Göttingen, Germany
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Abstract
Alzheimer's disease (AD) research has shown that patients with an inherited form of the disease carry mutations in the presenilin proteins or the amyloid precursor protein (APP). These disease-linked mutations result in increased production of the longer form of amyloid-beta (the primary component of the amyloid deposits found in AD brains). However, it is not clear how the presenilins contribute to this increase. New findings now show that the presenilins affect APP processing through their effects on gamma-secretase, an enzyme that cleaves APP. Also, it is known that the presenilins are involved in the cleavage of the Notch receptor, hinting that they either directly regulate gamma-secretase activity or themselves are protease enzymes. These findings suggest that the presenilins may prove to be valuable molecular targets for the development of drugs to combat AD.
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Affiliation(s)
- C Haass
- Adolf-Butenandt-Institute, Department of Biochemistry, Ludwig-Maximilians University Munich, Germany.
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34
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Herreman A, Hartmann D, Annaert W, Saftig P, Craessaerts K, Serneels L, Umans L, Schrijvers V, Checler F, Vanderstichele H, Baekelandt V, Dressel R, Cupers P, Huylebroeck D, Zwijsen A, Van Leuven F, De Strooper B. Presenilin 2 deficiency causes a mild pulmonary phenotype and no changes in amyloid precursor protein processing but enhances the embryonic lethal phenotype of presenilin 1 deficiency. Proc Natl Acad Sci U S A 1999; 96:11872-7. [PMID: 10518543 PMCID: PMC18379 DOI: 10.1073/pnas.96.21.11872] [Citation(s) in RCA: 387] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutations in the homologous presenilin 1 (PS1) and presenilin 2 (PS2) genes cause the most common and aggressive form of familial Alzheimer's disease. Although PS1 function and dysfunction have been extensively studied, little is known about the function of PS2 in vivo. To delineate the relationships of PS2 and PS1 activities and whether PS2 mutations involve gain or loss of function, we generated PS2 homozygous deficient (-/-) and PS1/PS2 double homozygous deficient mice. In contrast to PS1(-/-) mice, PS2(-/-) mice are viable and fertile and develop only mild pulmonary fibrosis and hemorrhage with age. Absence of PS2 does not detectably alter processing of amyloid precursor protein and has little or no effect on physiologically important apoptotic processes, indicating that Alzheimer's disease-causing mutations in PS2, as in PS1, result in gain of function. Although PS1(+/-) PS2( -/-) mice survive in relatively good health, complete deletion of both PS2 and PS1 genes causes a phenotype closely resembling full Notch-1 deficiency. These results demonstrate in vivo that PS1 and PS2 have partially overlapping functions and that PS1 is essential and PS2 is redundant for normal Notch signaling during mammalian embryological development.
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Affiliation(s)
- A Herreman
- Neuronal Cell Biology Laboratory, K.U.Leuven and Flanders Institute for Biotechnology, 3000 Leuven, Belgium
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Abstract
Mis-sense mutations of presenilin 1 increase the release of amyloidogenic peptide from amyloid precursor protein (APP) and are a major cause of familial Alzheimer's Disease. Loss-of-function mutations of presenilins in the mouse, Caenorhabditis elegans and Drosophila result in severe developmental defects caused by disturbed Notch signalling. Recent studies suggest that the diverse biological roles of presenilin 1 can be explained at the molecular level by its role in the proteolytic cleavage of the integral membrane domains of Notch and APP. This cleavage is a central switch in Notch signalling, while, for APP, its physiological role remains elusive. Evidence that presenilin 1 itself has catalytic properties could explain many of the biological and biochemical alterations caused by presenilin-1 deficiency or clinical mutations in presenilin 1. However, as presenilins reside in the endoplasmic reticulum and the cleavage of Notch and APP is believed to occur close to the cell membrane, the scientific field now faces a 'spatial paradox'.
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Affiliation(s)
- W Annaert
- Neuronal Cell Biology and Gene Transfer Laboratory, Centre for Human Genetics, Flanders Interuniversitary, Institute for Biotechnology (VIB4), Gasthuisberg, KULeuven, B-3000 Leuven, Belgium
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36
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Lévesque L, Annaert W, Craessaerts K, Mathews PM, Seeger M, Nixon RA, Van Leuven F, Gandy S, Westaway D, St George-Hyslop P, De Strooper B, Fraser PE. Developmental expression of wild-type and mutant presenilin-1 in hippocampal neurons from transgenic mice: evidence for novel species-specific properties of human presenilin-1. Mol Med 1999; 5:542-54. [PMID: 10501657 PMCID: PMC2230452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
Presenilins 1 (PS1) and 2 (PS2) are multispanning transmembrane proteins associated with familial Alzheimer disease (FAD). They are developmentally regulated, being expressed at highest levels during neuronal differentiation and are sustained at a lower level throughout life. We investigated the distribution and metabolism of endogenous murine PS1 as well as human wild-type (wtPS1) and the familial AD Met146Leu (M146L) mutant presenilins in dissociated cultures of hippocampal neurons derived from control and transgenic mice. We found that the PS1 endoproteolytic fragments and, to a lesser extent, the full-length protein, were expressed as early as day 3 post-plating. Both species increased until the cells were fully differentiated at day 12. Confocal microscopy revealed that presenilin is present in the Golgi and endoplasmic reticulum and, as in punctate, vesicle-like structures within developing neurites and growth cones. Using a human-specific PS1 antibody, we were able to independently examine the distribution of the transgenic protein which, although similar to the endogenous, showed some unique qualities. These included (i) some heterogeneity in the proteolytic fragments of human PS1; (ii) significantly reduced levels of full-length human PS1, possibly as a result of preferential processing; and (iii) a more discrete intracellular distribution of human PS1. Colocalization with organelle-specific proteins revealed that PS1 was located in a diffuse staining pattern in the MAP2-positive dendrites and in a punctate manner in GAP43-positive axons. PS1 showed considerable overlap with GAP43, particularly at the growth cones. Similar patterns of PS1 distribution were detected in cultures derived from transgenic animals expressing human wild-type or mutant presenilins. The studies demonstrate that mutant presenilins are not grossly different in their processing or distribution within cultured neurons, which may represent more physiological models as compared to transfection systems. Our data also suggest that the molecular pathology associated with PS1 mutations results from subtle alterations in presenilin function, which can be further investigated using these transgenic neuronal cell culture models.
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Affiliation(s)
- L Lévesque
- Department of Medical Biophysics, Laboratory of Medicine and Pathobiology, Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
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37
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Hartmann D, De Strooper B, Saftig P. Presenilin-1 deficiency leads to loss of Cajal-Retzius neurons and cortical dysplasia similar to human type 2 lissencephaly. Curr Biol 1999; 9:719-27. [PMID: 10421573 DOI: 10.1016/s0960-9822(99)80331-5] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BACKGROUND Presenilin-1 (PS1) is a transmembrane protein that is located in the endoplasmic reticulum and the cis Golgi apparatus. Missense mutations of PS1 that modify gamma-secretase function, leading to a pathologic processing of amyloid precursor protein, are an important cause of familial Alzheimer's disease. Physiologically, the presenilins are involved in the Notch and Wnt-beta-catenin signaling pathways. RESULTS PS1-deficient mice develop a cortical dysplasia resembling human type 2 lissencephaly, with leptomeningeal fibrosis and migration of cortical-plate neurons beyond their normal position into the marginal zone and subarachnoid space. This disorder of neuronal migration is associated with the disappearance of the majority of the cells of the marginal zone, notably most of the Cajal-Retzius pioneer neurons, between embryonic days E14 and E18, and is preceded and accompanied by disorganization of Notch-1 immunoreactivity on the neuronal cell membranes. The marginal zone also becomes depleted of the extracellular matrix protein reelin and chondroitin sulfate proteoglycans. At that stage PS1 is transiently expressed in leptomeningeal fibroblasts, which are mandatory for the trophic support of Cajal-Retzius neurons. CONCLUSIONS In agreement with models in which neuronal migration disorders have been linked to a defect in Cajal-Retzius cells, the loss of most of these cells in PS1-deficient mice leads to cortical dysplasia. Because PS1 is normally expressed in the leptomeninges, and these become fibrotic in the PS1-knockout mice, we favor the hypothesis that the loss of Cajal-Retzius cells is caused by a defective trophic interaction with leptomeningeal cells, possibly involving disruption of Notch signaling.
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Affiliation(s)
- D Hartmann
- Anatomisches Institut der CAU Kiel, Otto-Hahn-Platz 8, D-24 118, Kiel, Germany
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De Strooper B, Annaert W, Cupers P, Saftig P, Craessaerts K, Mumm JS, Schroeter EH, Schrijvers V, Wolfe MS, Ray WJ, Goate A, Kopan R. A presenilin-1-dependent gamma-secretase-like protease mediates release of Notch intracellular domain. Nature 1999; 398:518-22. [PMID: 10206645 DOI: 10.1038/19083] [Citation(s) in RCA: 1615] [Impact Index Per Article: 64.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Signalling through the receptor protein Notch, which is involved in crucial cell-fate decisions during development, requires ligand-induced cleavage of Notch. This cleavage occurs within the predicted transmembrane domain, releasing the Notch intracellular domain (NICD), and is reminiscent of gamma-secretase-mediated cleavage of beta-amyloid precursor protein (APP), a critical event in the pathogenesis of Alzheimer's disease. A deficiency in presenilin-1 (PS1) inhibits processing of APP by gamma-secretase in mammalian cells, and genetic interactions between Notch and PS1 homologues in Caenorhabditis elegans indicate that the presenilins may modulate the Notch signalling pathway. Here we report that, in mammalian cells, PS1 deficiency also reduces the proteolytic release of NICD from a truncated Notch construct, thus identifying the specific biochemical step of the Notch signalling pathway that is affected by PS1. Moreover, several gamma-secretase inhibitors block this same step in Notch processing, indicating that related protease activities are responsible for cleavage within the predicted transmembrane domains of Notch and APP. Thus the targeting of gamma-secretase for the treatment of Alzheimer's disease may risk toxicity caused by reduced Notch signalling.
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Affiliation(s)
- B De Strooper
- Neuronal Cell Biology and Gene Transfer Laboratory, Flanders Institute for Biotechnology (VIB4), Center for Human Genetics, KU Leuven, Belgium.
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Zhang Z, Hartmann H, Do VM, Abramowski D, Sturchler-Pierrat C, Staufenbiel M, Sommer B, van de Wetering M, Clevers H, Saftig P, De Strooper B, He X, Yankner BA. Destabilization of beta-catenin by mutations in presenilin-1 potentiates neuronal apoptosis. Nature 1998; 395:698-702. [PMID: 9790190 DOI: 10.1038/27208] [Citation(s) in RCA: 408] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mutations of the presenilin-1 gene are a major cause of familial early-onset Alzheimer's disease. Presenilin-1 can associate with members of the catenin family of signalling proteins, but the significance of this association is unknown. Here we show that presenilin-1 forms a complex with beta-catenin in vivo that increases beta-catenin stability. Pathogenic mutations in the presenilin-1 gene reduce the ability of presenilin-1 to stabilize beta-catenin, and lead to increased degradation of beta-catenin in the brains of transgenic mice. Moreover, beta-catenin levels are markedly reduced in the brains of Alzheimer's disease patients with presenilin-1 mutations. Loss of beta-catenin signalling increases neuronal vulnerability to apoptosis induced by amyloid-beta protein. Thus, mutations in presenilin-1 may increase neuronal apoptosis by altering the stability of beta-catenin, predisposing individuals to early-onset Alzheimer's disease.
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Affiliation(s)
- Z Zhang
- Department of Neurology, Harvard Medical School, The Children's Hospital, Boston, Massachusetts 02115, USA
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Moechars D, Lorent K, Dewachter I, Baekelandt V, De Strooper B, Van Leuven F. Transgenic mice expressing an alpha-secretion mutant of the amyloid precursor protein in the brain develop a progressive CNS disorder. Behav Brain Res 1998; 95:55-64. [PMID: 9754877 DOI: 10.1016/s0166-4328(97)00210-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Expression of alpha-secretion mutant APP/RK in mouse brain results in a progressive disorganization of the central nervous system, exemplified by behavioral deficits, premature death and neuropathology. Here we report on the progressive nature of this CNS disorder as indicated by the age dependency of the neophobic reaction in the open-field test. The earlier reported NMDA hypo-sensitivity in the transgenic APP/RK mice is likely to represent a subtle functional disturbance, since no changes in NMDA receptor density or distribution could be detected. None of the typical neuropathological hallmarks of Alzheimer's Disease, i.e. amyloid deposits and neurofibrillary tangles are detected in the brain of these transgenic mice. Nevertheless, the progressive CNS disorder elicited in the transgenic APP/RK mice recapitulates certain features and symptoms of patients with Alzheimer's disease as discussed.
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Affiliation(s)
- D Moechars
- Experimental Genetics Group, Center for Human Genetics and Vlaams Instituut voor Biotechnologie, K.U. Leuven, Belgium
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Simons M, Keller P, De Strooper B, Beyreuther K, Dotti CG, Simons K. Cholesterol depletion inhibits the generation of beta-amyloid in hippocampal neurons. Proc Natl Acad Sci U S A 1998; 95:6460-4. [PMID: 9600988 PMCID: PMC27798 DOI: 10.1073/pnas.95.11.6460] [Citation(s) in RCA: 870] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The amyloid precursor protein (APP) plays a crucial role in the pathogenesis of Alzheimer's disease. During intracellular transport APP undergoes a series of proteolytic cleavages that lead to the release either of an amyloidogenic fragment called beta-amyloid (Abeta) or of a nonamyloidogenic secreted form consisting of the ectodomain of APP (APPsec). It is Abeta that accumulates in the brain lesions that are thought to cause the disease. By reducing the cellular cholesterol level of living hippocampal neurons by 70% with lovastatin and methyl-beta-cyclodextrin, we show that the formation of Abeta is completely inhibited while the generation of APPsec is unperturbed. This inhibition of Abeta formation is accompanied by increased solubility in the detergent Triton X-100 and is fully reversible by the readdition of cholesterol to previously depleted cells. Our results show that cholesterol is required for Abeta formation to occur and imply a link between cholesterol, Abeta, and Alzheimer's disease.
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Affiliation(s)
- M Simons
- Cell Biology Programme, European Molecular Biology Laboratory, Meyerhofstrasse 1, Postfach 10.2209, D-69012 Heidelberg, Germany.
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De Strooper B, Saftig P, Craessaerts K, Vanderstichele H, Guhde G, Annaert W, Von Figura K, Van Leuven F. Deficiency of presenilin-1 inhibits the normal cleavage of amyloid precursor protein. Nature 1998; 391:387-90. [PMID: 9450754 DOI: 10.1038/34910] [Citation(s) in RCA: 1344] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Point mutations in the presenilin-1 gene (PS1) are a major cause of familial Alzheimer's disease. They result in a selective increase in the production of the amyloidogenic peptide amyloid-beta(1-42) by proteolytic processing of the amyloid precursor protein (APP). Here we investigate whether PS1 is also involved in normal APP processing in neuronal cultures derived from PS1-deficient mouse embryos. Cleavage by alpha- and beta-secretase of the extracellular domain of APP was not affected by the absence of PS1, whereas cleavage by gamma-secretase of the transmembrane domain of APP was prevented, causing carboxyl-terminal fragments of APP to accumulate and a fivefold drop in the production of amyloid peptide. Pulse-chase experiments indicated that PS1 deficiency specifically decreased the turnover of the membrane-associated fragments of APP. As in the regulation of cholesterol metabolism by proteolysis of a membrane-bound transcription factor, PS1 appears to facilitate a proteolytic activity that cleaves the integral membrane domain of APP. Our results indicate that mutations in PS1 that manifest clinically cause a gain of function and that inhibition of PS1 activity is a potential target for anti-amyloidogenic therapy in Alzheimer's disease.
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Affiliation(s)
- B De Strooper
- Experimental Genetics Group, Flemish Institute for Biotechnology (VIB4), Center for Human Genetics, K.U.Leuven, Belgium.
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De Strooper B, Beullens M, Contreras B, Levesque L, Craessaerts K, Cordell B, Moechars D, Bollen M, Fraser P, George-Hyslop PS, Van Leuven F. Phosphorylation, subcellular localization, and membrane orientation of the Alzheimer's disease-associated presenilins. J Biol Chem 1997; 272:3590-8. [PMID: 9013610 DOI: 10.1074/jbc.272.6.3590] [Citation(s) in RCA: 235] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Presenilins 1 and 2 are unglycosylated proteins with apparent molecular mass of 45 and 50 kDa, respectively, in transfected COS-1 and Chinese hamster ovary cells. They colocalize with proteins from the endoplasmic reticulum and the Golgi apparatus in transfected and untransfected cells. In COS-1 cells low amounts of intact endogeneous presenilin 1 migrating at 45 kDa are detected together with relative larger amounts of presenilin 1 fragments migrating between 18 and 30 kDa. The presenilins have a strong tendency to form aggregates (mass of 100-250 kDa) in SDS-polyacrylamide gel electrophoresis, which can be partially resolved when denatured by SDS at 37 degrees C instead of 95 degrees C. Sulfation, glycosaminoglycan modification, or acylation of the presenilins was not observed, but both proteins are posttranslationally phosphorylated on serine residues. The mutations Ala-246 --> Glu or Cys-410 --> Tyr that cause Alzheimer's disease do not interfere with the biosynthesis or phosphorylation of presenilin 1. Finally, using low concentrations of digitonin to selectively permeabilize the cell membrane but not the endoplasmic reticulum membrane, it is demonstrated that the two major hydrophilic domains of presenilin 1 are oriented to the cytoplasm. The current investigation documents the posttranslational modifications and subcellular localization of the presenilins and indicates that postulated interactions with amyloid precursor protein metabolism should occur in the early compartments of the biosynthetic pathway.
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Saftig P, Peters C, von Figura K, Craessaerts K, Van Leuven F, De Strooper B. Amyloidogenic processing of human amyloid precursor protein in hippocampal neurons devoid of cathepsin D. J Biol Chem 1996; 271:27241-4. [PMID: 8910296 DOI: 10.1074/jbc.271.44.27241] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
betaA4-Amyloid peptide, the main component of the amyloid plaques in the brain of Alzheimer's disease patients is produced from amyloid precursor protein (APP) by proteolytical processing. Several lines of evidence suggest a direct role for cathepsin D, the major endosomal/lysosomal aspartic endopeptidase, in betaA4-amyloid peptide generation. Here we tested this hypothesis using primary cultures of hippocampal neurons derived from cathepsin D-deficient (knock out) mice and expressing wild-type human APP and two clinical APP variants via recombinant Semliki Forest virus. We demonstrate APP secretory processing, production of carboxyl-terminal amyloid fragments, and secretion of the betaA4-amyloid peptide in the complete absence of cathepsin D. The results rule out cathepsin D as a critical component of alpha-, beta-, or gamma-secretase and therefore as a primary target for drugs aimed at decreasing the betaA4-amyloid peptide burden in Alzheimer's disease.
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Affiliation(s)
- P Saftig
- Zentrum Biochemie und Molekular Zellbiologie, Abteilung Biochemie II, Universität Göttingen, Gosslerstrasse 12D, 37073 Göttingen,
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Tienari PJ, De Strooper B, Ikonen E, Simons M, Weidemann A, Czech C, Hartmann T, Ida N, Multhaup G, Masters CL, Van Leuven F, Beyreuther K, Dotti CG. The beta-amyloid domain is essential for axonal sorting of amyloid precursor protein. EMBO J 1996. [DOI: 10.1002/j.1460-2075.1996.tb00907.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Tienari PJ, De Strooper B, Ikonen E, Simons M, Weidemann A, Czech C, Hartmann T, Ida N, Multhaup G, Masters CL, Van Leuven F, Beyreuther K, Dotti CG. The beta-amyloid domain is essential for axonal sorting of amyloid precursor protein. EMBO J 1996; 15:5218-29. [PMID: 8895567 PMCID: PMC452266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We have analysed the axonal sorting signals of amyloid precursor protein (APP). Wild-type and mutant versions of human APP were expressed in hippocampal neurons using the Semliki forest virus system. We show that wild-type APP and mutations implicated in Alzheimer's disease and another brain beta-amyloidosis are sorted to the axon. By analysis of deletion mutants we found that the membrane-inserted APP ectodomain but not the cytoplasmic tail is required for axonal sorting. Systematic deletions of the APP ectodomain identified two regions required for axonal delivery: one encoded by exons 11-15 in the carbohydrate domain, the other encoded by exons 16-17 in the juxtamembraneous beta-amyloid domain. Treatment of the cells with the N-glycosylation inhibitor tunicamycin induced missorting of wild-type APP, supporting the importance of glycosylation in axonal sorting of APP. The data revealed a hierarchy of sorting signals on APP: the beta-amyloid-dependent membrane proximal signal was the major contributor to axonal sorting, while N-glycosylation had a weaker effect. Furthermore, recessive somatodendritic signals, most likely in the cytoplasmic tail, directed the protein to the dendrites when the ectodomain was deleted. Analysis of detergent solubility of APP and another axonally delivered protein, hemagglutinin, demonstrated that only hemagglutinin formed CHAPS-insoluble complexes, suggesting distinct mechanisms of axonal sorting for these two proteins. This study is the first delineation of sorting requirements of an axonally targeted protein in polarized neurons and indicates that the beta-amyloid domain plays a major role in axonal delivery of APP.
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Affiliation(s)
- P J Tienari
- Cell Biology Programme, European Molecular Biology Laboratories (EMBL), Heidelberg, Germany
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Moechars D, Lorent K, De Strooper B, Dewachter I, Van Leuven F. Expression in brain of amyloid precursor protein mutated in the alpha-secretase site causes disturbed behavior, neuronal degeneration and premature death in transgenic mice. EMBO J 1996. [DOI: 10.1002/j.1460-2075.1996.tb00468.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Moechars D, Lorent K, De Strooper B, Dewachter I, Van Leuven F. Expression in brain of amyloid precursor protein mutated in the alpha-secretase site causes disturbed behavior, neuronal degeneration and premature death in transgenic mice. EMBO J 1996; 15:1265-74. [PMID: 8635459 PMCID: PMC450029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
A double mutation in the alpha-secretase site in the betaA4 region of mouse amyloid precursor protein (APP) reduced its secretion from COS cells, polarized MDCK cells and rat primary neurons. Expression of this mutant in the brain of mice, using the neuron-specific elements of the mouse Thy-1 gene promoter, resulted in transgenic mice that became progressively hyperactive, displayed seizures and died prematurely. In three different transgenic lines the severity of the phenotype was related directly to the expression levels of the transgene, estimated by both mRNA and protein levels. In addition, homozygous mice derived from each transgenic strain showed more severe symptoms which also occurred earlier in life than in heterozygotes. The observed symptoms were, however, not essentially different in the different lines. Increased aggressiveness, disturbed responses to kainic acid and N-methyl-D-aspartate, neophobia and deficiency in exploratory behavior were demonstrated in these mice. In the brain, the observed neuropathological changes included necrosis, apoptosis and astrogliosis in the hippocampus, cortex and other areas. The data demonstrate that incomplete or incorrect alpha-secretase processing of APP results in severe neurotoxicity and that this effect is expressed in a dominant manner.
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Affiliation(s)
- D Moechars
- Experimental Genetics Group, Center for Human Genetics, Leuven, Belgium
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De Strooper B, Moechars D, Tienari P, Simons M, Beyreuther K, Dotti C, Van Leuven F. 174 Processing of APP in polarized epithelial cells and neurons: relationships among cell types. Neurobiol Aging 1996. [DOI: 10.1016/s0197-4580(96)80176-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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De Strooper B, Wu RR, Jaspers M, Van der Schueren B, Vekemans S, Carmeliet G, Van Leuven F, Van Den Oord J, Cassiman JJ. A 68-kD antigen, which is probably an N-terminal fragment of the VLA-5 alpha 5-subunit, is specific for differentiating keratinocytes. Dermatology 1996; 193:212-20. [PMID: 8944343 DOI: 10.1159/000246248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND During terminal differentiation, basal keratinocytes lose gradually contact with the basement membrane, a process accompanied by the progressive functional down-regulation and loss of integrin expression. Understanding the molecular nature of this complex mechanism will eventually lead to insight into the pathogenesis of differentiation disorders of the epidermis, e.g. psoriasis. OBJECTIVE The monoclonal antibody 8D9 against the very late antigen 5 (VLA-5) integrin subunit was used to study the expression and down-regulation of this protein in several experimental paradigms of keratinocyte differentiation. METHODS Primary cultures of human keratinocytes were prepared and used as such, or after induction of terminal differentiation with methylcellulose and/or calcium. Expression of the 8D9 epitope was analyzed using immunoblotting, protein chemistry and immunocytochemistry on cultured cells and on skin biopsies from control and psoriatic patients. RESULTS AND CONCLUSION The monoclonal antibody 8D9 reacts with the alpha 5-subunit of human VLA-5 integrin and with a 68-kD antigen that is strongly expressed in differentiating keratinocytes in vitro and in the cornified layers of human skin in vivo. Psoriatic skin showed additional immunoreactivity in the upper spinous and granular layers. Based on indirect immunological and chemical evidence we suggest that the 68-kD protein is an amino-terminal degradation product of the alpha 5-subunit, which provides a new and interesting marker of differentiating keratinocytes.
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Affiliation(s)
- B De Strooper
- Center for Human Genetics, University of Leuven, Belgium
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