201
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Zhang X, Yu CJ, Sisodia SS. The topology of pen-2, a γ-secretase subunit, revisited: evidence for a reentrant loop and a single pass transmembrane domain. Mol Neurodegener 2015; 10:39. [PMID: 26296997 PMCID: PMC4546279 DOI: 10.1186/s13024-015-0037-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Accepted: 08/13/2015] [Indexed: 12/04/2022] Open
Abstract
Background The γ-secretase complex, composed of transmembrane proteins termed presenilin (PS), anterior pharynx defective (APH), nicastrin (NCT), and presenilin enhancer-2 (Pen-2) catalyzes intramembranous hydrolysis of a variety of Type I membrane protein substrates. In order to understand aspects of subunit assembly, interactions, dynamics and catalysis, it is essential to clarify the membrane topology of each polypeptide. Hydophathicity plots predict that the 101 amino acid Pen-2 molecule has two hydrophobic domains (HP1 and HP2) that may serve as transmembrane spanning domains. Earlier reports indicated that transiently overexpressed Pen-2 uses these two hydrophobic domains as transmembrane helices that generates a “U-shaped” hairpin topology with both amino- (N-) and carboxyl-(C-) termini facing the lumen. In this report, we have reexamined the topology of endogenous Pen-2 and Pen-2 chimeras that are stably expressed in mammalian cells, and have assessed the function of these molecules in rescuing γ-secretase activity in Pen-2-deficient fibroblasts. Results We confirm that the Pen-2 C-terminus is lumenal, but the N-terminus of Pen-2 is exposed to the cytoplasm, thus indicating that HP1 does not traverse the lipid bilayer as a transmembrane domain. Domain swapping studies reveal the importance of specific regions within the first hydrophobic domain of Pen-2 that are critical for generating the topology that is a prerequisite for mediating PS1 endoproteolysis and γ-secretase activity. Finally, we report that the first fourteen amino acids of the Pen-2 HP1 are required for γ-secretase activity. Conclusions We propose that the first hydrophobic domain of Pen-2 forms a structure similar to a reentrant loop while the second hydrophobic domain spans the lipid bilayer.
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Affiliation(s)
- Xulun Zhang
- Department of Neurobiology, The University of Chicago, 947 E. 58th St. MC0928, Chicago, Il 60637, USA.
| | - Chunjiang J Yu
- Department of Neurobiology, The University of Chicago, 1128 S. Eastside Ave, Oak Park, Chicago, Il 60304, USA.
| | - Sangram S Sisodia
- Department of Neurobiology, The University of Chicago, 947 E. 58th St. MC0928, Chicago, Il 60637, USA.
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202
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Gertsik N, Chau DM, Li YM. γ-Secretase Inhibitors and Modulators Induce Distinct Conformational Changes in the Active Sites of γ-Secretase and Signal Peptide Peptidase. ACS Chem Biol 2015; 10:1925-31. [PMID: 26030233 DOI: 10.1021/acschembio.5b00321] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
γ-Secretase inhibitors (GSIs) and modulators (GSMs) are at the frontline of cancer and Alzheimer's disease research, respectively. While both are therapeutically promising, not much is known about their interactions with proteins other than γ-secretase. Signal peptide peptidase (SPP), like γ-secretase, is a multispan transmembrane aspartyl protease that catalyzes regulated intramembrane proteolysis. We used active site-directed photophore walking probes to study the effects of different GSIs and GSMs on the active sites of γ-secretase and SPP and found that nontransition state GSIs inhibit labeling of γ-secretase by activity-based probes but enhance labeling of SPP. The opposite is true of GSMs, which have little effect on the labeling of γ-secretase but diminish labeling of SPP. These results demonstrate that GSIs and GSMs are altering the structure of not only γ-secretase but also SPP, leading to potential changes in enzyme activity and specificity that may impact the clinical outcomes of these molecules.
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Affiliation(s)
- Natalya Gertsik
- 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
- Clinical
Genetics Unit Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia
| | - Yue-Ming Li
- Molecular
Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
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203
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Cui J, Wang X, Li X, Wang X, Zhang C, Li W, Zhang Y, Gu H, Xie X, Nan F, Zhao J, Pei G. Targeting the γ-/β-secretase interaction reduces β-amyloid generation and ameliorates Alzheimer's disease-related pathogenesis. Cell Discov 2015; 1:15021. [PMID: 27462420 PMCID: PMC4860824 DOI: 10.1038/celldisc.2015.21] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 06/18/2015] [Indexed: 12/19/2022] Open
Abstract
Despite decades of intense global effort, no disease-modifying drugs for Alzheimer’s disease have emerged. Molecules targeting catalytic activities of γ-secretase or β-site APP-cleaving enzyme 1 (BACE1) have been beset by undesired side effects. We hypothesized that blocking the interaction between BACE1 and γ-secretase subunit presenilin-1 (PS1) might offer an alternative strategy to selectively suppress Aβ generation. Through high-throughput screening, we discovered that 3-α-akebonoic acid (3AA) interferes with PS1/BACE1 interaction and reduces Aβ production. Structural analogs of 3AA were systematically synthesized and the functional analog XYT472B was identified. Photo-activated crosslinking and biochemical competition assays showed that 3AA and XYT472B bind to PS1, interfere with PS1/BACE1 interaction, and reduce Aβ production, whereas sparing secretase activities. Furthermore, treatment of APP/PS1 mice with XYT472B alleviated cognitive dysfunction and Aβ-related pathology. Together, our results indicate that chemical interference of PS1/BACE1 interaction is a promising strategy for Alzheimer’s disease therapeutics.
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Affiliation(s)
- Jin Cui
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences , Shanghai, China
| | - Xiaoyin Wang
- State Key Laboratory of Drug Research, The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai, China
| | - Xiaohang Li
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences , Shanghai, China
| | - Xin Wang
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences , Shanghai, China
| | - Chenlu Zhang
- State Key Laboratory of Drug Research, The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai, China
| | - Wei Li
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences , Shanghai, China
| | - Yangming Zhang
- State Key Laboratory of Drug Research, The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai, China
| | - Haifeng Gu
- State Key Laboratory of Drug Research, The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai, China
| | - Xin Xie
- State Key Laboratory of Drug Research, The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai, China
| | - Fajun Nan
- State Key Laboratory of Drug Research, The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai, China
| | - Jian Zhao
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China; Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Gang Pei
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China; School of Life Science and Technology, Collaborative Innovation Center for Brain Science, Tongji University, Shanghai, China
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204
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Abstract
Dysfunction of the intramembrane protease γ-secretase is thought to cause Alzheimer's disease, with most mutations derived from Alzheimer's disease mapping to the catalytic subunit presenilin 1 (PS1). Here we report an atomic structure of human γ-secretase at 3.4 Å resolution, determined by single-particle cryo-electron microscopy. Mutations derived from Alzheimer's disease affect residues at two hotspots in PS1, each located at the centre of a distinct four transmembrane segment (TM) bundle. TM2 and, to a lesser extent, TM6 exhibit considerable flexibility, yielding a plastic active site and adaptable surrounding elements. The active site of PS1 is accessible from the convex side of the TM horseshoe, suggesting considerable conformational changes in nicastrin extracellular domain after substrate recruitment. Component protein APH-1 serves as a scaffold, anchoring the lone transmembrane helix from nicastrin and supporting the flexible conformation of PS1. Ordered phospholipids stabilize the complex inside the membrane. Our structure serves as a molecular basis for mechanistic understanding of γ-secretase function.
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205
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Wang X, Cui J, Li W, Zeng X, Zhao J, Pei G. γ-Secretase Modulators and Inhibitors Induce Different Conformational Changes of Presenilin 1 Revealed by FLIM and FRET. J Alzheimers Dis 2015; 47:927-37. [DOI: 10.3233/jad-150313] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Xin Wang
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Jin Cui
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Wei Li
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xianglu Zeng
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Shanghai Key Laboratory of Signaling and Disease Research, Laboratory of Receptor-based Bio-medicine, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jian Zhao
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Gang Pei
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, and the Collaborative Innovation Center for Brain Science, Tongji University, Shanghai, China
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206
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Modeling the complex pathology of Alzheimer's disease in Drosophila. Exp Neurol 2015; 274:58-71. [PMID: 26024860 DOI: 10.1016/j.expneurol.2015.05.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 05/13/2015] [Accepted: 05/17/2015] [Indexed: 12/18/2022]
Abstract
Alzheimer's disease (AD) is the leading cause of dementia and the most common neurodegenerative disorder. AD is mostly a sporadic disorder and its main risk factor is age, but mutations in three genes that promote the accumulation of the amyloid-β (Aβ42) peptide revealed the critical role of amyloid precursor protein (APP) processing in AD. Neurofibrillary tangles enriched in tau are the other pathological hallmark of AD, but the lack of causative tau mutations still puzzles researchers. Here, we describe the contribution of a powerful invertebrate model, the fruit fly Drosophila melanogaster, to uncover the function and pathogenesis of human APP, Aβ42, and tau. APP and tau participate in many complex cellular processes, although their main function is microtubule stabilization and the to-and-fro transport of axonal vesicles. Additionally, expression of secreted Aβ42 induces prominent neuronal death in Drosophila, a critical feature of AD, making this model a popular choice for identifying intrinsic and extrinsic factors mediating Aβ42 neurotoxicity. Overall, Drosophila has made significant contributions to better understand the complex pathology of AD, although additional insight can be expected from combining multiple transgenes, performing genome-wide loss-of-function screens, and testing anti-tau therapies alone or in combination with Aβ42.
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207
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Grimm MOW, Mett J, Stahlmann CP, Grösgen S, Haupenthal VJ, Blümel T, Hundsdörfer B, Zimmer VC, Mylonas NT, Tanila H, Müller U, Grimm HS, Hartmann T. APP intracellular domain derived from amyloidogenic β- and γ-secretase cleavage regulates neprilysin expression. Front Aging Neurosci 2015; 7:77. [PMID: 26074811 PMCID: PMC4443740 DOI: 10.3389/fnagi.2015.00077] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 04/24/2015] [Indexed: 01/30/2023] Open
Abstract
Alzheimer's disease (AD) is characterized by an accumulation of Amyloid-β (Aβ), released by sequential proteolytic processing of the amyloid precursor protein (APP) by β - and γ-secretase. Aβ peptides can aggregate, leading to toxic Aβ oligomers and amyloid plaque formation. Aβ accumulation is not only dependent on de novo synthesis but also on Aβ degradation. Neprilysin (NEP) is one of the major enzymes involved in Aβ degradation. Here we investigate the molecular mechanism of NEP regulation, which is up to now controversially discussed to be affected by APP processing itself. We found that NEP expression is highly dependent on the APP intracellular domain (AICD), released by APP processing. Mouse embryonic fibroblasts devoid of APP processing, either by the lack of the catalytically active subunit of the γ-secretase complex [presenilin (PS) 1/2] or by the lack of APP and the APP-like protein 2 (APLP2), showed a decreased NEP expression, activity and protein level. Similar results were obtained by utilizing cells lacking a functional AICD domain (APPΔCT15) or expressing mutations in the genes encoding for PS1. AICD supplementation or retransfection with an AICD encoding plasmid could rescue the down-regulation of NEP further strengthening the link between AICD and transcriptional NEP regulation, in which Fe65 acts as an important adaptor protein. Especially AICD generated by the amyloidogenic pathway seems to be more involved in the regulation of NEP expression. In line, analysis of NEP gene expression in vivo in six transgenic AD mouse models (APP and APLP2 single knock-outs, APP/APLP2 double knock-out, APP-swedish, APP-swedish/PS1Δexon9, and APPΔCT15) confirmed the results obtained in cell culture. In summary, in the present study we clearly demonstrate an AICD-dependent regulation of the Aβ-degrading enzyme NEP in vitro and in vivo and elucidate the underlying mechanisms that might be beneficial to develop new therapeutic strategies for the treatment of AD.
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Affiliation(s)
- Marcus O W Grimm
- Department of Experimental Neurology, Saarland University Homburg, Germany ; Department of Neurodegeneration and Neurobiology, Saarland University Homburg, Germany ; Deutsches Institut für DemenzPrävention, Saarland University Homburg, Germany
| | - Janine Mett
- Department of Experimental Neurology, Saarland University Homburg, Germany
| | | | - Sven Grösgen
- Department of Experimental Neurology, Saarland University Homburg, Germany
| | - Viola J Haupenthal
- Department of Experimental Neurology, Saarland University Homburg, Germany
| | - Tamara Blümel
- Department of Experimental Neurology, Saarland University Homburg, Germany
| | | | - Valerie C Zimmer
- Department of Experimental Neurology, Saarland University Homburg, Germany
| | - Nadine T Mylonas
- Department of Experimental Neurology, Saarland University Homburg, Germany
| | - Heikki Tanila
- Department of Neurobiology, A.I. Virtanen Institute, University of Eastern Finland Kuopio, Finland ; Department of Neurology, Kuopio University Hospital Kuopio, Finland
| | - Ulrike Müller
- Department of Functional Genomics, Institute for Pharmacy and Molecular Biotechnology, Heidelberg University Heidelberg, Germany
| | - Heike S Grimm
- Department of Experimental Neurology, Saarland University Homburg, Germany
| | - Tobias Hartmann
- Department of Experimental Neurology, Saarland University Homburg, Germany ; Department of Neurodegeneration and Neurobiology, Saarland University Homburg, Germany ; Deutsches Institut für DemenzPrävention, Saarland University Homburg, Germany
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208
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Overexpression of the Insulin-Like Growth Factor II Receptor Increases β-Amyloid Production and Affects Cell Viability. Mol Cell Biol 2015; 35:2368-84. [PMID: 25939386 DOI: 10.1128/mcb.01338-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 04/20/2015] [Indexed: 12/26/2022] Open
Abstract
Amyloid β (Aβ) peptides originating from amyloid precursor protein (APP) in the endosomal-lysosomal compartments play a critical role in the development of Alzheimer's disease (AD), the most common type of senile dementia affecting the elderly. Since insulin-like growth factor II (IGF-II) receptors facilitate the delivery of nascent lysosomal enzymes from the trans-Golgi network to endosomes, we evaluated their role in APP metabolism and cell viability using mouse fibroblast MS cells deficient in the murine IGF-II receptor and corresponding MS9II cells overexpressing the human IGF-II receptors. Our results show that IGF-II receptor overexpression increases the protein levels of APP. This is accompanied by an increase of β-site APP-cleaving enzyme 1 levels and an increase of β- and γ-secretase enzyme activities, leading to enhanced Aβ production. At the cellular level, IGF-II receptor overexpression causes localization of APP in perinuclear tubular structures, an increase of lipid raft components, and increased lipid raft partitioning of APP. Finally, MS9II cells are more susceptible to staurosporine-induced cytotoxicity, which can be attenuated by β-secretase inhibitor. Together, these results highlight the potential contribution of IGF-II receptor to AD pathology not only by regulating expression/processing of APP but also by its role in cellular vulnerability.
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209
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Dewji NN, Singer SJ, Masliah E, Rockenstein E, Kim M, Harber M, Horwood T. Peptides of presenilin-1 bind the amyloid precursor protein ectodomain and offer a novel and specific therapeutic approach to reduce ß-amyloid in Alzheimer's disease. PLoS One 2015; 10:e0122451. [PMID: 25923432 PMCID: PMC4414571 DOI: 10.1371/journal.pone.0122451] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 02/12/2015] [Indexed: 12/19/2022] Open
Abstract
β-Amyloid (Aβ) accumulation in the brain is widely accepted to be critical to the development of Alzheimer's disease (AD). Current efforts at reducing toxic Aβ40 or 42 have largely focused on modulating γ-secretase activity to produce shorter, less toxic Aβ, while attempting to spare other secretase functions. In this paper we provide data that offer the potential for a new approach for the treatment of AD. The method is based on our previous findings that the production of Aβ from the interaction between the β-amyloid precursor protein (APP) and Presenilin (PS), as part of the γ-secretase complex, in cell culture is largely inhibited if the entire water-soluble NH2-terminal domain of PS is first added to the culture. Here we demonstrate that two small, non-overlapping water-soluble peptides from the PS-1 NH2-terminal domain can substantially and specifically inhibit the production of total Aβ as well as Aβ40 and 42 in vitro and in vivo in the brains of APP transgenic mice. These results suggest that the inhibitory activity of the entire amino terminal domain of PS-1 on Aβ production is largely focused in a few smaller sequences within that domain. Using biolayer interferometry and confocal microscopy we provide evidence that peptides effective in reducing Aβ give a strong, specific and biologically relevant binding with the purified ectodomain of APP 695. Finally, we demonstrate that the reduction of Aβ by the peptides does not affect the catalytic activities of β- or γ-secretase, or the level of APP. P4 and P8 are the first reported protein site-specific small peptides to reduce Aβ production in model systems of AD. These peptides and their derivatives offer new potential drug candidates for the treatment of AD.
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Affiliation(s)
- Nazneen N. Dewji
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, United States of America
- Cenna Biosciences Incorporated, 505 Coast Boulevard, Suite 302, La Jolla, CA, 92037, United States of America
- * E-mail:
| | - S. Jonathan Singer
- Department of Biology, University of California San Diego, La Jolla, CA, 92093, United States of America
- Cenna Biosciences Incorporated, 505 Coast Boulevard, Suite 302, La Jolla, CA, 92037, United States of America
| | - Eliezer Masliah
- Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, United States of America
- Department of Pathology, University of California San Diego, La Jolla, CA, 92093, United States of America
| | - Edward Rockenstein
- Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, United States of America
| | - Mihyun Kim
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, United States of America
- Cenna Biosciences Incorporated, 505 Coast Boulevard, Suite 302, La Jolla, CA, 92037, United States of America
| | - Martha Harber
- FortéBio, Pall Corporation, 1360 Willow Rd, Suite 201, Menlo Park, CA, 94025, United States of America
| | - Taylor Horwood
- Department of Neuroscience Imaging Core, University of California San Diego, La Jolla, CA, 92093, United States of America
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210
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Abstract
The four-component intramembrane protease γ-secretase is intricately linked to the development of Alzheimer's disease. Despite recent structural advances, the transmembrane segments (TMs) of γ-secretase remain to be specifically assigned. Here we report a 3D structure of human γ-secretase at 4.32-Å resolution, determined by single-particle, electron cryomicroscopy in the presence of digitonin and with a T4 lysozyme fused to the amino terminus of presenilin 1 (PS1). The overall structure of this human γ-secretase is very similar to that of wild-type γ-secretase determined in the presence of amphipols. The 20 TMs are unambiguously assigned to the four components, revealing principles of subunit assembly. Within the transmembrane region, PS1 is centrally located, with its amino-terminal fragment (NTF) packing against Pen-2 and its carboxyl-terminal fragment (CTF) interacting with Aph-1. The only TM of nicastrin associates with Aph-1 at the thick end of the TM horseshoe, and the extracellular domain of nicastrin directly binds Pen-2 at the thin end. TM6 and TM7 in PS1, which harbor the catalytic aspartate residues, are located on the convex side of the TM horseshoe. This structure serves as an important framework for understanding the function and mechanism of γ-secretase.
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211
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Murakami K. Conformation-specific antibodies to target amyloid β oligomers and their application to immunotherapy for Alzheimer's disease. Biosci Biotechnol Biochem 2015; 78:1293-305. [PMID: 25130729 DOI: 10.1080/09168451.2014.940275] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Amyloid β-protein (Aβ) oligomers, intermediates of Aβ aggregation, cause cognitive impairment and synaptotoxicity in the pathogenesis of Alzheimer's disease (AD). Immunotherapy using anti-Aβ antibody is one of the most promising approaches for AD treatment. However, most clinical trials using conventional sequence-specific antibodies have proceeded with difficulty. This is probably due to the unintended removal of the non-pathological monomer and fibrils of Aβ as well as the pathological oligomers by these antibodies that recognize Aβ sequence, which is not involved in synaptotoxicity. Several efforts have been made recently to develop conformation-specific antibodies that target the tertiary structure of Aβ oligomers. Here, we review the recent findings of Aβ oligomers and anti-Aβ antibodies including our own, and discuss their potential as therapeutic and diagnostic tools.
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Affiliation(s)
- Kazuma Murakami
- a Division of Food Science and Biotechnology , Graduate School of Agriculture, Kyoto University , Kyoto , Japan
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212
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Cooperative roles of hydrophilic loop 1 and the C-terminus of presenilin 1 in the substrate-gating mechanism of γ-secretase. J Neurosci 2015; 35:2646-56. [PMID: 25673856 DOI: 10.1523/jneurosci.3164-14.2015] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
γ-Secretase is a multisubunit protease complex that is responsible for generating amyloid-β peptides, which are associated with Alzheimer disease. The catalytic subunit of γ-secretase is presenilin 1 (PS1), which contains an initial substrate-binding site that is distinct from the catalytic site. Processive cleavage is suggested in the intramembrane-cleaving mechanism of γ-secretase. However, it largely remains unknown as to how γ-secretase recognizes its substrate during proteolysis. Here, we identified that the α-helical structural region of hydrophilic loop 1 (HL1) and the C-terminal region of human PS1 are distinct substrate-binding sites. Mutational analyses revealed that substrate binding to the HL1 region is critical for both ε- and γ-cleavage, whereas binding to the C-terminal region hampers γ-cleavage. Moreover, we propose that substrate binding triggers conformational changes in PS1, rendering it suitable for catalysis. Our data provide new insights into the complicated catalytic mechanism of PS1.
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213
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Chu Y, Peng X, Long Z, Wang K, Luo S, Sharma A, He G. Distribution and expression of Pen-2 in the central nervous system of APP/PS1 double transgenic mice. Acta Biochim Biophys Sin (Shanghai) 2015; 47:258-66. [PMID: 25736404 DOI: 10.1093/abbs/gmv010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The γ-secretase complex catalyzes the final cleavage step of amyloid β-protein precursor (APP) to generate amyloid β (Aβ) peptide, a pathogenic component of senile plaques in the brain of Alzheimer's disease (AD) patients. Recent studies have shown that presenilin enhancer-2 (Pen-2), presenilin (PS, including PS1 and PS2), nicastrin, and anterior pharynx-defective 1 are essential components of the γ-secretase. The structure and function of Pen-2 in vitro have been well defined. However, little is known about the neuroanatomical distribution and expression of Pen-2 in the central nervous system (CNS) of AD model mice. We report here, using various methods such as immunohistochemical staining and immunoblotting, that Pen-2 is widely expressed at specific neuronal cells of major areas in AD model mice, including the olfactory bulb, basal forebrain, striatum, cortex, hippocampus, amygdala, thalamus, hypothalamus, cerebellum, brainstem, and spinal cord. It is co-expressed with PS1 in specific neuronal cells in mouse brain. Pen-2 is distributed much more extensively than extracellular amyloid deposits, suggesting the importance of other factors in localized amyloid deposition. Pen-2 is localized predominantly in cell membrane and cytoplasma in adult AD mice, but only distributed at cell membrane in controls. At the early stages of postnatal development, the expression level of Pen-2 is relatively high in CNS, but declines, gradually in adult mice. The present study provides an anatomical basis for Pen-2 as a key component of γ-secretase complex in the brain of developing and adult mice, and Pen-2 might be closely related to Aβ burden in aging nervous system.
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Affiliation(s)
- Yanan Chu
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China
| | - Xuehua Peng
- Department of Radiology, Pediatric Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Zhiming Long
- Department of Anatomy, Chongqing Medical University, Chongqing 400016, China
| | - Kejian Wang
- Department of Anatomy, Chongqing Medical University, Chongqing 400016, China
| | - Shifang Luo
- Department of Anatomy, Chongqing Medical University, Chongqing 400016, China
| | - Akhilesh Sharma
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China
| | - Guiqiong He
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China Department of Anatomy, Chongqing Medical University, Chongqing 400016, China
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214
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Matz A, Halamoda-Kenzaoui B, Hamelin R, Mosser S, Alattia JR, Dimitrov M, Moniatte M, Fraering PC. Identification of new Presenilin-1 phosphosites: implication for γ-secretase activity and Aβ production. J Neurochem 2015; 133:409-21. [PMID: 25458374 DOI: 10.1111/jnc.12996] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 11/02/2014] [Accepted: 11/10/2014] [Indexed: 02/02/2023]
Abstract
An important pathological hallmark of Alzheimer's disease (AD) is the deposition of amyloid-beta (Aβ) peptides in the brain parenchyma, leading to neuronal death and impaired learning and memory. The protease γ-secretase is responsible for the intramembrane proteolysis of the amyloid-β precursor protein (APP), which leads to the production of the toxic Aβ peptides. Thus, an attractive therapeutic strategy to treat AD is the modulation of the γ-secretase activity, to reduce Aβ42 production. Because phosphorylation of proteins is a post-translational modification known to modulate the activity of many different enzymes, we used electrospray (LC-MS/MS) mass spectrometry to identify new phosphosites on highly purified human γ-secretase. We identified 11 new single or double phosphosites in two well-defined domains of Presenilin-1 (PS1), the catalytic subunit of the γ-secretase complex. Next, mutagenesis and biochemical approaches were used to investigate the role of each phosphosite in the maturation and activity of γ-secretase. Together, our results suggest that the newly identified phosphorylation sites in PS1 do not modulate γ-secretase activity and the production of the Alzheimer's Aβ peptides. Individual PS1 phosphosites shall probably not be considered therapeutic targets for reducing cerebral Aβ plaque formation in AD. In this study, we identified 11 new phosphosites in Presenilin-1 (PS1), the catalytic subunit of the Alzheimer's γ-secretase complex. By combining a mutagenesis approach with cell-based and cell-free γ-secretase assays, we demonstrate that the new phosphosites do not modulate the maturation and activity of γ-secretase. Individual PS1 phosphosites shall thus not be considered therapeutic targets for reducing cerebral Aβ plaque formation in Alzheimer's Disease. Aβ, amyloid beta.
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Affiliation(s)
- Alexandre Matz
- Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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215
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Cavaleri F. Paradigm shift redefining molecular, metabolic and structural events in Alzheimer's disease involves a proposed contribution by transition metals. Defined lengthy preclinical stage provides new hope to circumvent advancement of disease- and age-related neurodegeneration. Med Hypotheses 2015; 84:460-9. [PMID: 25691377 DOI: 10.1016/j.mehy.2015.01.044] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Accepted: 01/30/2015] [Indexed: 12/28/2022]
Abstract
It is estimated that 5.5 Million North Americans suffer from varying degrees of Alzheimer's disease (AD) and by the year 2050 it may be one in 85 people globally (100 Million). It will be shown that heavy metal toxicity plays a significant role in sporadic AD. Although current literature speaks to involvement of metal ions (via Fenton reaction), studies and reviewers have yet to link cellular events including known structural changes such as amyloid plaque development to this metal toxicity the way it is proposed here. Contrary to the current AD model which positions BACE1 (β-secretase) as an aberrant or AD-advancing enzyme, it is proposed herein that the neuron's protective counteraction to this metal toxicity is, in fact, a justified increase in BACE1 activity and amyloid precursor protein (APP) processing to yield more secreted APP (sAPP) and β-amyloid peptide in response to metal toxicity. This new perspective which justifies a functional role for APP, BACE1 enzyme activity and the peptide products from this activity may at first appear to be counterintuitive. Compelling evidence, however, is presented and a mechanism is shown herein that validate BACE1 recruitment and the resulting β-amyloid protein as strategic countermeasures serving the cell effectively against neuro-impeding disease. It is proposed that β-amyloid peptide chelates and sequesters free heavy metals in the extracellular medium to aggregate as amyloid plaque while unchelated β-amyloid migrates across the cell membrane to chelate intracellular free divalent metals. The sequestered intracellular metal is subsequently chaperoned as a metallo-peptide to cross the plasma membrane and aggregate as amyloid plaques extracellularly. The BACE1 countermeasure is not genetic or metabolic aberration; and this novel conclusion demonstrates that it must not be inhibited as currently targeted. APP, BACE1, β-amyloid peptide, and sAPP play positive roles against the preclinical oxidative load that predates AD symptoms for as long as 20 years. A healthy neuron may tolerate free metal toxicity, such as iron in the case of injury-induced amyloid, for as long as twenty years due to this very BACE1 activity. In later stages, the uncontrolled metals and ROS are compounded by other factors which together overcome this BACE1/β-amyloid protein countermeasure. This results in a sudden increase in IL-1 leading to Tau's hyperphosphorylation as cited and eventually to Tau dissociation from the microtubule cytoskeleton interrupting cell trafficking. At this later stage of AD the β-amyloid protein which once served as a vehicle to escort toxic metals to the extracellular medium and a trap to form a relatively benign extraneuronal disposal site is no longer translocated due to interruption of trafficking and now accumulates intracellularly facilitating hyper-oxidative ROS levels and contributes to irreversible neuron apoptosis.
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Affiliation(s)
- Franco Cavaleri
- Brain Research Center, UBC Hospital, 2211 Wesbrook Mall, Vancouver, BC V6T 2B5, Canada.
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216
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Takasugi N, Sasaki T, Shinohara M, Iwatsubo T, Tomita T. Synthetic ceramide analogues increase amyloid-β 42 production by modulating γ-secretase activity. Biochem Biophys Res Commun 2015; 457:194-9. [DOI: 10.1016/j.bbrc.2014.12.087] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 12/19/2014] [Indexed: 01/02/2023]
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217
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Gertsik N, Chiu D, Li YM. Complex regulation of γ-secretase: from obligatory to modulatory subunits. Front Aging Neurosci 2015; 6:342. [PMID: 25610395 PMCID: PMC4285130 DOI: 10.3389/fnagi.2014.00342] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 12/09/2014] [Indexed: 11/29/2022] Open
Abstract
γ-Secretase is a four subunit, 19-pass transmembrane enzyme that cleaves amyloid precursor protein (APP), catalyzing the formation of amyloid beta (Aβ) peptides that form amyloid plaques, which contribute to Alzheimer’s disease (AD) pathogenesis. γ-Secretase also cleaves Notch, among many other type I transmembrane substrates. Despite its seemingly promiscuous enzymatic capacity, γ-secretase activity is tightly regulated. This regulation is a function of many cellular entities, including but not limited to the essential γ-secretase subunits, nonessential (modulatory) subunits, and γ-secretase substrates. Regulation is also accomplished by an array of cellular events, such as presenilin (active subunit of γ-secretase) endoproteolysis and hypoxia. In this review we discuss how γ-secretase is regulated with the hope that an advanced understanding of these mechanisms will aid in the development of effective therapeutics for γ-secretase-associated diseases like AD and Notch-addicted cancer.
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Affiliation(s)
- Natalya Gertsik
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center New York, NY, USA ; Biochemistry and Molecular Biology Program, Weill Graduate School of Medical Sciences of Cornell University New York, NY, USA
| | - Danica Chiu
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center New York, NY, USA ; Program of Pharmacology, Weill Graduate School of Medical Sciences of Cornell University New York, NY, USA
| | - Yue-Ming Li
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center New York, NY, USA ; Program of Pharmacology, Weill Graduate School of Medical Sciences of Cornell University New York, NY, USA
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218
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Nagai N, Ito Y, Tanino T. Effect of High Glucose Levels on Amyloid β Production in Retinas of Spontaneous Diabetes Mellitus Otsuka Long-Evans Tokushima Fatty Rats. Biol Pharm Bull 2015; 38:601-10. [DOI: 10.1248/bpb.b14-00819] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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219
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Abstract
Increased amyloid beta (Aβ) production by sequential cleavage of the amyloid precursor protein (APP) by the β- and γ-secretases contributes to the etiological basis of Alzheimer's disease (AD). This process requires APP and the secretases to be in the same subcellular compartments, such as the endosomes. Since all membrane organelles in the endomembrane system are kinetically and functionally linked, any defects in the trafficking and sorting machinery would be expected to change the functional properties of the whole system. The Golgi is a primary organelle for protein trafficking, sorting and modifications, and Golgi defects have been reported in AD. Here we hypothesize that Golgi fragmentation in AD accelerates APP trafficking and Aβ production. Furthermore, Golgi defects may perturb the proper trafficking and processing of many essential neuronal proteins, resulting in compromised neuronal function. Therefore, molecular tools that can restore Golgi structure and function could prove useful as potential drugs for AD treatment.
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Affiliation(s)
- Gunjan Joshi
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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220
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Chen WT, Hsieh YF, Huang YJ, Lin CC, Lin YT, Liu YC, Lien CC, Cheng IHJ. G206D Mutation of Presenilin-1 Reduces Pen2 Interaction, Increases Aβ42/Aβ40 Ratio and Elevates ER Ca(2+) Accumulation. Mol Neurobiol 2014; 52:1835-1849. [PMID: 25394380 DOI: 10.1007/s12035-014-8969-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 10/28/2014] [Indexed: 12/23/2022]
Abstract
Early-onset familial Alzheimer's disease (AD) is most commonly associated with the mutations in presenilin-1 (PS1). PS1 is the catalytic component of the γ-secretase complex, which cleaves amyloid precursor protein to produce amyloid-β (Aβ), the major cause of AD. Presenilin enhancer 2 (Pen2) is critical for activating γ-secretase and exporting PS1 from endoplasmic reticulum (ER). Among all the familial AD-linked PS1 mutations, mutations at the G206 amino acid are the most adjacent position to the Pen2 binding site. Here, we characterized the effect of a familial AD-linked PS1 G206D mutation on the PS1-Pen2 interaction and the accompanied alteration in γ-secretase-dependent and -independent functions. We found that the G206D mutation reduced PS1-Pen2 interaction, but did not abolish γ-secretase formation and PS1 endoproteolysis. For γ-secretase-dependent function, the G206D mutation increased Aβ42 production but not Notch cleavage. For γ-secretase-independent function, this mutation disrupted the ER calcium homeostasis but not lysosomal calcium homeostasis and autophagosome maturation. Impaired ER calcium homeostasis may due to the reduced mutant PS1 level in the ER. Although this mutation did not alter the cell survival under stress, both increased Aβ42 ratio and disturbed ER calcium regulation could be the mechanisms underlying the pathogenesis of the familial AD-linked PS1 G206D mutation.
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Affiliation(s)
- Wei-Ting Chen
- Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan.,Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan.,Institute of Biochemistry and Molecular Biology, School of Life Science, National Yang-Ming University, Taipei, Taiwan
| | - Yi-Fang Hsieh
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Yan-Jing Huang
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Che-Ching Lin
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Yen-Tung Lin
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Yu-Chao Liu
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Cheng-Chang Lien
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Irene Han-Juo Cheng
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan. .,Brain Research Center, National Yang-Ming University, Taipei, Taiwan. .,Infection and Immunity Research Center, National Yang-Ming University, Taipei, Taiwan. .,Immunology Center, Taipei Veterans General Hospital, Taipei, Taiwan. .,Institute of Brain Science, School of Medicine, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei, 112, Taiwan.
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221
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Zhang X, Hoey R, Koide A, Dolios G, Paduch M, Nguyen P, Wu X, Li Y, Wagner SL, Wang R, Koide S, Sisodia SS. A synthetic antibody fragment targeting nicastrin affects assembly and trafficking of γ-secretase. J Biol Chem 2014; 289:34851-61. [PMID: 25352592 DOI: 10.1074/jbc.m114.609636] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The γ-secretase complex, composed of presenilin, nicastrin (NCT), anterior pharynx-defective 1 (APH-1), and presenilin enhancer 2 (PEN-2), is assembled in a highly regulated manner and catalyzes the intramembranous proteolysis of many type I membrane proteins, including Notch and amyloid precursor protein. The Notch family of receptors plays important roles in cell fate specification during development and in adult tissues, and aberrant hyperactive Notch signaling causes some forms of cancer. γ-Secretase-mediated processing of Notch at the cell surface results in the generation of the Notch intracellular domain, which associates with several transcriptional coactivators involved in nuclear signaling events. On the other hand, γ-secretase-mediated processing of amyloid precursor protein leads to the production of amyloid β (Aβ) peptides that play an important role in the pathogenesis of Alzheimer disease. We used a phage display approach to identify synthetic antibodies that specifically target NCT and expressed them in the single-chain variable fragment (scFv) format in mammalian cells. We show that expression of a NCT-specific scFv clone, G9, in HEK293 cells decreased the production of the Notch intracellular domain but not the production of amyloid β peptides that occurs in endosomal and recycling compartments. Biochemical studies revealed that scFvG9 impairs the maturation of NCT by associating with immature forms of NCT and, consequently, prevents its association with the other components of the γ-secretase complex, leading to degradation of these molecules. The reduced cell surface levels of mature γ-secretase complexes, in turn, compromise the intramembranous processing of Notch.
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Affiliation(s)
| | - Robert Hoey
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
| | - Akiko Koide
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
| | - Georgia Dolios
- the Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Marcin Paduch
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
| | - Phuong Nguyen
- the Department of Neurosciences, University of California, San Diego School of Medicine, La Jolla, California 92093, and
| | - Xianzhong Wu
- Molecular Pharmacology and Chemistry, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Yueming Li
- Molecular Pharmacology and Chemistry, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Steven L Wagner
- the Department of Neurosciences, University of California, San Diego School of Medicine, La Jolla, California 92093, and
| | - Rong Wang
- the Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Shohei Koide
- Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637
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222
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223
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Abstract
Presenilin is a membrane-embedded intramembrane-cleaving protease with a conserved catalytic G×GD motif. It is the catalytic subunit of γ-secretase, which plays critical roles in developmental biology and the molecular etiology of Alzheimer disease, together with three membrane protein cofactors, nicastrin, Aph-1 and Pen-2. Biochemical and enzymatic analyses have revealed that γ-secretase executes two types of proteolytic activities on a single substrate; an endopeptidase-like cleavage followed by carboxypeptidase-like processive cleavage. Utilizing small molecule inhibitors/modulators together with the substituted cysteine accessibility method, we identified certain residues and regions of presenilin that contribute to the formation of a catalytic pore structure within the lipid bilayer required for its intramembrane-cleaving activity. Recently, determination of the crystal structure of the archaeal presenilin homologue has confirmed the intramembranous location of the two conserved and essential aspartates. In this review, I will introduce the recent progresses in the understanding of the molecular mechanisms of action of this atypical protease.
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Affiliation(s)
- Taisuke Tomita
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
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224
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Allosteric regulation of γ-secretase activity by a phenylimidazole-type γ-secretase modulator. Proc Natl Acad Sci U S A 2014; 111:10544-9. [PMID: 25009180 DOI: 10.1073/pnas.1402171111] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
γ-Secretase is an intramembrane-cleaving protease responsible for the generation of amyloid-β (Aβ) peptides. Recently, a series of compounds called γ-secretase modulators (GSMs) has been shown to decrease the levels of long toxic Aβ species (i.e., Aβ42), with a concomitant elevation of the production of shorter Aβ species. In this study, we show that a phenylimidazole-type GSM allosterically induces conformational changes in the catalytic site of γ-secretase to augment the proteolytic activity. Analyses using the photoaffinity labeling technique and systematic mutational studies revealed that the phenylimidazole-type GSM targets a previously unidentified extracellular binding pocket within the N-terminal fragment of presenilin (PS). Collectively, we provide a model for the mechanism of action of the phenylimidazole-type GSM in which binding at the luminal side of PS induces a conformational change in the catalytic center of γ-secretase to modulate Aβ production.
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225
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Wolfe MS. Unlocking truths of γ-secretase in Alzheimer's disease: what is the translational potential? FUTURE NEUROLOGY 2014; 9:419-429. [PMID: 26146489 DOI: 10.2217/fnl.14.35] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Considerable evidence, particularly from genetics, points to the aggregation-prone amyloid β-peptide as a pathogenic entity in Alzheimer's disease. Hence, the proteases that produce this peptide from its precursor protein have been prime targets for the development of potential therapeutics. One of these proteases, γ-secretase, has been a particular focus. Many inhibitors and modulators of this membrane-embedded protease complex have been identified, with some brought into late-stage clinical trials, where they have spectacularly failed. The reasons for these failures will be discussed, along with recent findings on the mechanism of γ-secretase and of Alzheimer-causing mutations that may suggest new strategies for targeting this enzyme.
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Affiliation(s)
- Michael S Wolfe
- Center for Neurologic Disease, Brigham & Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Tel.: +1 617 525 5511
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226
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Holmes O, Paturi S, Selkoe DJ, Wolfe MS. Pen-2 is essential for γ-secretase complex stability and trafficking but partially dispensable for endoproteolysis. Biochemistry 2014; 53:4393-406. [PMID: 24941111 PMCID: PMC4216188 DOI: 10.1021/bi500489j] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
The
19-transmembrane γ-secretase complex generates the amyloid
β-peptide of Alzheimer’s disease by intramembrane proteolysis
of the β-amyloid precursor
protein. This complex is comprised of presenilin, Aph1, nicastrin,
and Pen-2. The exact function and mechanism of the highly conserved
Pen-2 subunit remain poorly understood. Using systematic mutagenesis,
we confirm and extend our understanding of which key regions and specific
residues play roles in various aspects of γ-secretase function,
including maturation, localization, and activity, but not processivity.
In general, mutations (1) within the first half of transmembrane domain
(TMD) 1 of Pen-2 decreased PS1 endoproteolysis and γ-secretase
proteolytic activity, (2) within the second half of TMD1 increased
proteolytic activity, (3) within the cytosolic loop region decreased
proteolytic activity, (4) within TMD2 decreased PS1 endoproteolysis,
(5) within the first half of TMD2 decreased proteolytic activity,
and (6) within C-terminal residues decreased proteolytic activity.
Specific mutational effects included N33A in TMD1 causing an increase
in γ-secretase complexes at the cell surface and a modest decrease
in stability and the previously unreported I53A mutation in the loop
region reducing stability 10-fold and proteolytic activity by half.
In addition, we confirm that minor PS1 endoproteolysis can occur in
the complete absence of Pen-2. Together, these data suggest that rather
than solely being a catalyst for γ-secretase endoproteolysis,
Pen-2 may also stabilize the complex prior to PS1 endoproteolysis,
allowing time for full assembly and proper trafficking.
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Affiliation(s)
- Oliver Holmes
- Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School , Boston, Massachusetts 02115, United States
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227
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Lu P, Bai XC, Ma D, Xie T, Yan C, Sun L, Yang G, Zhao Y, Zhou R, Scheres SHW, Shi Y. Three-dimensional structure of human γ-secretase. Nature 2014; 512:166-170. [PMID: 25043039 DOI: 10.1038/nature13567] [Citation(s) in RCA: 265] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/09/2014] [Indexed: 12/12/2022]
Abstract
The γ-secretase complex, comprising presenilin 1 (PS1), PEN-2, APH-1 and nicastrin, is a membrane-embedded protease that controls a number of important cellular functions through substrate cleavage. Aberrant cleavage of the amyloid precursor protein (APP) results in aggregation of amyloid-β, which accumulates in the brain and consequently causes Alzheimer's disease. Here we report the three-dimensional structure of an intact human γ-secretase complex at 4.5 Å resolution, determined by cryo-electron-microscopy single-particle analysis. The γ-secretase complex comprises a horseshoe-shaped transmembrane domain, which contains 19 transmembrane segments (TMs), and a large extracellular domain (ECD) from nicastrin, which sits immediately above the hollow space formed by the TM horseshoe. Intriguingly, nicastrin ECD is structurally similar to a large family of peptidases exemplified by the glutamate carboxypeptidase PSMA. This structure serves as an important basis for understanding the functional mechanisms of the γ-secretase complex.
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Affiliation(s)
- Peilong Lu
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Xiao-Chen Bai
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Dan Ma
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Tian Xie
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Chuangye Yan
- State Key Laboratory of Bio-membrane and Membrane Biotechnology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Linfeng Sun
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Guanghui Yang
- State Key Laboratory of Bio-membrane and Membrane Biotechnology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Yanyu Zhao
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Rui Zhou
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Sjors H W Scheres
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Yigong Shi
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
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228
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Holmes O, Paturi S, Wolfe MS, Selkoe DJ. Functional analysis and purification of a Pen-2 fusion protein for γ-secretase structural studies. J Neurochem 2014; 131:94-100. [PMID: 24865334 DOI: 10.1111/jnc.12772] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 05/22/2014] [Indexed: 01/24/2023]
Abstract
The 19-transmembrane, multisubunit γ-secretase complex generates the amyloid β-peptide (Aβ) of Alzheimer's disease (AD) by an unusual intramembrane proteolysis of the β-amyloid precursor protein. The complex, which similarly processes many other type 1 transmembrane substrates, is composed of presenilin, Aph1, nicastrin, and presenilin enhancer (Pen-2), all of which are necessary for proper complex maturation and enzymatic activity. Obtaining a high-resolution atomic structure of the intact complex would greatly aid the rational design of compounds to modulate activity but is a very difficult task. A complementary method is to generate structures for each individual subunit to allow one to build a model of the entire complex. Here, we describe a method by which recombinant human Pen-2 can be purified from bacteria to > 95% purity at milligram quantities per liter, utilizing a maltose binding protein tag to both increase solubility and facilitate purification. Expressing the same construct in mammalian cells, we show that the large N-terminal maltose binding protein tag on Pen-2 still permits incorporation into the complex and subsequent presenilin-1 endoproteolysis, nicastrin glycosylation and proteolytic activity. These new methods provide valuable tools to study the structure and function of Pen-2 and the γ-secretase complex.
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Affiliation(s)
- Oliver Holmes
- Center for Neurologic Diseases, Brigham and Women's Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
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229
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GGA1 overexpression attenuates amyloidogenic processing of the amyloid precursor protein in Niemann-Pick type C cells. Biochem Biophys Res Commun 2014; 450:160-5. [PMID: 24866237 DOI: 10.1016/j.bbrc.2014.05.083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 05/19/2014] [Indexed: 11/23/2022]
Abstract
Alzheimer's disease (AD) and a rare inherited disorder of cholesterol transport, Niemann-Pick type C (NPC) share several similarities including aberrant APP processing and increased Aβ production. Previously, we have shown that the AD-like phenotype in NPC model cells involves cholesterol-dependent enhanced APP cleavage by β-secretase and accumulation of both APP and BACE1 within endocytic compartments. Since retrograde transport of BACE1 from endocytic compartments to the trans-Golgi network (TGN) is regulated by the Golgi-localized γ-ear containing ADP ribosylation factor-binding protein 1 (GGA1), we analyzed in this work a potential role of GGA1 in the AD-like phenotype of NPC1-null cells. Overexpression of GGA1 caused a shift in APP processing towards the non-amyloidogenic pathway by increasing the localization of APP at the cell surface. However, the observed effect appear to be independent on the subcellular localization and phosphorylation state of BACE1. These findings show that the AD-like phenotype of NPC model cells can be partly reverted by promoting a non-amyloidogenic processing of APP through the upregulation of GGA1 supporting its preventive role against AD.
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230
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Wang Y, Thinakaran G, Kar S. Overexpression of the IGF-II/M6P receptor in mouse fibroblast cell lines differentially alters expression profiles of genes involved in Alzheimer's disease-related pathology. PLoS One 2014; 9:e98057. [PMID: 24846272 PMCID: PMC4028253 DOI: 10.1371/journal.pone.0098057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 04/25/2014] [Indexed: 11/29/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common type of senile dementia affecting elderly people. The processing of amyloid precursor protein (APP) leading to the generation of β-amyloid (Aβ) peptide contributes to neurodegeneration and development of AD pathology. The endocytic trafficking pathway, which comprises of the endosomes and lysosomes, acts as an important site for Aβ generation, and endocytic dysfunction has been linked to increased Aβ production and loss of neurons in AD brains. Since insulin-like growth factor-II (IGF-II) receptor plays a critical role in the transport of lysosomal enzymes from the trans-Golgi network to endosomes, it is likely that the receptor may have a role in regulating Aβ metabolism in AD pathology. However, very little is known on how altered levels of the IGF-II receptor can influence the expression/function of various molecules involved in AD pathology. To address this issue, we evaluated the expression profiles of 87 selected genes related to AD pathology in mouse fibroblast MS cells that are deficient in murine IGF-II receptor and corresponding MS9II cells overexpressing ∼500 times the human IGF-II receptors. Our results reveal that an elevation in IGF-II receptor levels alters the expression profiles of a number of genes including APP as well as enzymes regulating Aβ production, degradation and clearance mechanisms. Additionally, it influences the expression of various lysosomal enzymes and protein kinases that are involved in Aβ toxicity. IGF-II receptor overexpression also alters expression of several genes involved in intracellular signalling as well as cholesterol metabolism, which play a critical role in AD pathology. The altered gene profiles observed in this study closely match with the corresponding protein levels, with a few exceptions. These results, taken together, suggest that an elevation in IGF-II receptor levels can influence the expression profiles of transcripts as well as proteins that are involved in AD pathogenesis.
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Affiliation(s)
- Yanlin Wang
- Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, Canada
| | - Gopal Thinakaran
- Departments of Neurobiology, Neurology and Pathology, The University of Chicago, Chicago, Illinois, United States of America
| | - Satyabrata Kar
- Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, Canada
- Department of Medicine (Neurology), University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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231
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Funamoto S, Sasaki T, Ishihara S, Nobuhara M, Nakano M, Watanabe-Takahashi M, Saito T, Kakuda N, Miyasaka T, Nishikawa K, Saido TC, Ihara Y. Substrate ectodomain is critical for substrate preference and inhibition of γ-secretase. Nat Commun 2014; 4:2529. [PMID: 24108142 PMCID: PMC3826621 DOI: 10.1038/ncomms3529] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 09/02/2013] [Indexed: 01/18/2023] Open
Abstract
Understanding the substrate recognition mechanism of γ-secretase is a key step for establishing substrate-specific inhibition of amyloid β-protein (Aβ) production. However, it is widely believed that γ-secretase is a promiscuous protease and that its substrate-specific inhibition is elusive. Here we show that γ-secretase distinguishes the ectodomain length of substrates and preferentially captures and cleaves substrates containing a short ectodomain. We also show that a subset of peptides containing the CDCYCxxxxCxCxSC motif binds to the amino terminus of C99 and inhibits Aβ production in a substrate-specific manner. Interestingly, these peptides suppress β-secretase-dependent cleavage of APP, but not that of sialyltransferase 1. Most importantly, intraperitoneal administration of peptides into mice results in a significant reduction in cerebral Aβ levels. This report provides direct evidence of the substrate preference of γ-secretase and its mechanism. Our results demonstrate that the ectodomain of C99 is a potent target for substrate-specific anti-Aβ therapeutics to combat Alzheimer’s disease. γ-Secretase inhibitors are studied for their potential to treat Alzheimer’s disease, but their use is limited by side effects. Funamoto et al. show that γ-secretase preferentially cleaves substrates with short ectodomains and that inhibitors based on these ectodomains reduce disease-like pathology in mice.
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Affiliation(s)
- Satoru Funamoto
- 1] Department of Neuropathology, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan [2] Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan
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232
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Kanatsu K, Morohashi Y, Suzuki M, Kuroda H, Watanabe T, Tomita T, Iwatsubo T. Decreased CALM expression reduces Aβ42 to total Aβ ratio through clathrin-mediated endocytosis of γ-secretase. Nat Commun 2014; 5:3386. [PMID: 24577224 DOI: 10.1038/ncomms4386] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Accepted: 02/05/2014] [Indexed: 01/08/2023] Open
Abstract
A body of evidence suggests that aberrant metabolism of amyloid-β peptide (Aβ) underlies the aetiology of Alzheimer disease (AD). Recently, a single-nucleotide polymorphism in phosphatidylinositol binding clathrin assembly protein (PICALM/CALM) gene, which encodes a protein implicated in the clathrin-mediated endocytosis, was identified as a genetic protective factor for AD, although its mechanistic details have little been explored. Here we show that loss of CALM leads to the selective decrease in the production ratio of the pathogenic Aβ species, Aβ42. Active form of γ-secretase is constitutively endocytosed via the clathrin-mediated pathway in a CALM dependent manner. Alteration in the rate of clathrin-mediated endocytosis of γ-secretase causes a shift in its steady-state localization, which consequently impacts on the production ratio of Aβ42. Our study identifies CALM as an endogenous modulator of γ-secretase activity by regulating its endocytosis and also as an excellent target for Aβ42-lowering AD therapeutics.
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Affiliation(s)
- Kunihiko Kanatsu
- 1] Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan [2]
| | - Yuichi Morohashi
- 1] Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan [2] Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Tokyo 113-0033, Japan [3]
| | - Mai Suzuki
- Department of Biological Science, Graduate School of Humanities and Sciences, Nara Women's University, Nara 630-8506, Japan
| | - Hiromasa Kuroda
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Toshio Watanabe
- Department of Biological Science, Graduate School of Humanities and Sciences, Nara Women's University, Nara 630-8506, Japan
| | - Taisuke Tomita
- 1] Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan [2] Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Tokyo 113-0033, Japan
| | - Takeshi Iwatsubo
- 1] Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan [2] Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Tokyo 113-0033, Japan [3] Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
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233
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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: 39] [Impact Index Per Article: 3.9] [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.
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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
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234
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Ohki Y, Shimada N, Tominaga A, Osawa S, Higo T, Yokoshima S, Fukuyama T, Tomita T, Iwatsubo T. Binding of longer Aβ to transmembrane domain 1 of presenilin 1 impacts on Aβ42 generation. Mol Neurodegener 2014; 9:7. [PMID: 24410857 PMCID: PMC3896738 DOI: 10.1186/1750-1326-9-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/10/2014] [Indexed: 11/18/2022] Open
Abstract
Background Amyloid-β peptide ending at 42nd residue (Aβ42) is believed as a pathogenic peptide for Alzheimer disease. Although γ-secretase is a responsible protease to generate Aβ through a processive cleavage, the proteolytic mechanism of γ-secretase at molecular level is poorly understood. Results We found that the transmembrane domain (TMD) 1 of presenilin (PS) 1, a catalytic subunit for the γ-secretase, as a key modulatory domain for Aβ42 production. Aβ42-lowering and -raising γ-secretase modulators (GSMs) directly targeted TMD1 of PS1 and affected its structure. A point mutation in TMD1 caused an aberrant secretion of longer Aβ species including Aβ45 that are the precursor of Aβ42. We further found that the helical surface of TMD1 is involved in the binding of Aβ45/48 and that the binding was altered by GSMs as well as TMD1 mutation. Conclusions Binding between PS1 TMD1 and longer Aβ is critical for Aβ42 production.
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Affiliation(s)
| | | | | | | | | | | | | | - Taisuke Tomita
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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235
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Jiang S, Li Y, Zhang X, Bu G, Xu H, Zhang YW. Trafficking regulation of proteins in Alzheimer's disease. Mol Neurodegener 2014; 9:6. [PMID: 24410826 PMCID: PMC3891995 DOI: 10.1186/1750-1326-9-6] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 12/15/2013] [Indexed: 12/12/2022] Open
Abstract
The β-amyloid (Aβ) peptide has been postulated to be a key determinant in the pathogenesis of Alzheimer’s disease (AD). Aβ is produced through sequential cleavage of the β-amyloid precursor protein (APP) by β- and γ-secretases. APP and relevant secretases are transmembrane proteins and traffic through the secretory pathway in a highly regulated fashion. Perturbation of their intracellular trafficking may affect dynamic interactions among these proteins, thus altering Aβ generation and accelerating disease pathogenesis. Herein, we review recent progress elucidating the regulation of intracellular trafficking of these essential protein components in AD.
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Affiliation(s)
| | | | | | | | | | - Yun-wu Zhang
- Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian 361102, China.
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236
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Scarpini E, Cogiamanian F. Alzheimer’s disease: from molecular pathogenesis to innovative therapies. Expert Rev Neurother 2014; 3:619-30. [DOI: 10.1586/14737175.3.5.619] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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237
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Tomita T. Secretase inhibitors and modulators for Alzheimer’s disease treatment. Expert Rev Neurother 2014; 9:661-79. [DOI: 10.1586/ern.09.24] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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238
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Gertsik N, Ballard TE, Am Ende CW, Johnson DS, Li YM. Development of CBAP-BPyne, a probe for γ-secretase and presenilinase. MEDCHEMCOMM 2014; 5:338-341. [PMID: 24914408 DOI: 10.1039/c3md00281k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
γ-Secretase undergoes endoproteolysis of its catalytic subunit, presenilin (PS), to form PS N-terminal and C-terminal fragments (PS1-NTF/CTF), which generate the active site. PS endoproteolysis, catalyzed by presenilinase (PSase), remains poorly understood and requires novel chemical approaches for its mechanistic study. CBAP is a dual inhibitor that suppresses both γ-secretase and PSase activities. To probe γ-secretase and PSase activity in cells, we have synthesized the clickable photoaffinity probe CBAP-BPyne. We found that CBAP-BPyne specifically labels PS1-NTF and signal peptide peptidase (SPP). CBAP-BPyne is a valuable tool to directly study the mechanism of endoproteolysis.
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Affiliation(s)
- Natalya Gertsik
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA ; Biochemistry and Molecular Biology Program, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA
| | - T Eric Ballard
- Pfizer Worldwide Research and Development, Neuroscience Medicinal Chemistry and Chemical Biology, Cambridge, MA 02139, USA ; Pfizer Worldwide Research and Development, Neuroscience Medicinal Chemistry, Groton, CT 06340, USA
| | - Christopher W Am Ende
- Pfizer Worldwide Research and Development, Neuroscience Medicinal Chemistry, Groton, CT 06340, USA
| | - Douglas S Johnson
- Pfizer Worldwide Research and Development, Neuroscience Medicinal Chemistry and Chemical Biology, Cambridge, MA 02139, USA
| | - Yue-Ming Li
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
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239
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Thomas RS, Hvoslef-Eide M, Good MA, Kidd EJ. Inhibition of amyloid-β production by anti-amyloid precursor protein antibodies in primary mouse cortical neurones. Neuroreport 2013; 24:1058-61. [PMID: 24145776 PMCID: PMC4493351 DOI: 10.1097/wnr.0000000000000055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Current therapies for Alzheimer's disease only treat the symptoms of the disease. We have previously developed a novel monoclonal antibody, 2B3, which binds to the β-secretase cleavage site in amyloid precursor protein (APP) and reduces the production of amyloid-β (Aβ) in human cell lines. To determine whether the antibody was likely to be effective in mouse models of amyloid pathology in vivo, we investigated whether 2B3 could also bind to APP in mouse primary cortical neurones. Primary cortical neurones were produced from E15.5-17.5 C57Bl/6 wild-type and transgenic APP/V717I (London mutation) embryos. The percentage of the neuronal population was determined by immunocytochemistry. Cells were treated with 10 μg/ml 2B3 or an irrelevant IgG for 48 h and Aβ40 levels determined by ELISA. The population of cells was found to contain over 75% neurones and 2B3 bound effectively to these cells. No differences in Aβ40 were detected between wild-type and transgenic cells. Importantly, 2B3 significantly inhibited the production of Aβ40 by 75.15±1.37% of the media control, whereas an irrelevant IgG only significantly reduced Aβ40 levels by 23.35±5.55% of the media control. The reduction in Aβ40 produced by 2B3 was significantly greater than that caused by the IgG. These data indicate that 2B3 binds to APP in mouse neurones and can inhibit Aβ40, similar to our previous findings. The antibody is probably therefore acting by steric hindrance of β-secretase and these data suggest that it will be effective in mice in vivo and could be an alternative potential therapy for Alzheimer's disease.
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Affiliation(s)
- Rhian S. Thomas
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff, CF10 3NB, U.K
| | - Martha Hvoslef-Eide
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff, CF10 3NB, U.K
- School of Psychology, Cardiff University, Tower Building, 70 Park Place, Cardiff, CF10 3AT, U.K
| | - Mark A. Good
- School of Psychology, Cardiff University, Tower Building, 70 Park Place, Cardiff, CF10 3AT, U.K
| | - Emma J. Kidd
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff, CF10 3NB, U.K
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240
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Jurisch-Yaksi N, Sannerud R, Annaert W. A fast growing spectrum of biological functions of γ-secretase in development and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2815-27. [PMID: 24099003 DOI: 10.1016/j.bbamem.2013.04.016] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 04/03/2013] [Accepted: 04/11/2013] [Indexed: 12/17/2022]
Abstract
γ-secretase, which assembles as a tetrameric complex, is an aspartyl protease that proteolytically cleaves substrate proteins within their membrane-spanning domain; a process also known as regulated intramembrane proteolysis (RIP). RIP regulates signaling pathways by abrogating or releasing signaling molecules. Since the discovery, already >15 years ago, of its catalytic component, presenilin, and even much earlier with the identification of amyloid precursor protein as its first substrate, γ-secretase has been commonly associated with Alzheimer's disease. However, starting with Notch and thereafter a continuously increasing number of novel substrates, γ-secretase is becoming linked to an equally broader range of biological processes. This review presents an updated overview of the current knowledge on the diverse molecular mechanisms and signaling pathways controlled by γ-secretase, with a focus on organ development, homeostasis and dysfunction. This article is part of a Special Issue entitled: Intramembrane Proteases.
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Affiliation(s)
- Nathalie Jurisch-Yaksi
- Laboratory for Membrane Trafficking, VIB-Center for the Biology of Disease & Department for Human Genetics (KU Leuven), Leuven, Belgium
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241
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Wolfe MS. Toward the structure of presenilin/γ-secretase and presenilin homologs. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1828:2886-97. [PMID: 24099007 PMCID: PMC3801419 DOI: 10.1016/j.bbamem.2013.04.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 04/03/2013] [Accepted: 04/11/2013] [Indexed: 01/30/2023]
Abstract
Presenilin is the catalytic component of the γ-secretase complex, a membrane-embedded aspartyl protease that plays a central role in biology and in the pathogenesis of Alzheimer's disease. Upon assembly with its three protein cofactors (nicastrin, Aph-1 and Pen-2), presenilin undergoes autoproteolysis into two subunits, each of which contributes one of the catalytic aspartates to the active site. A family of presenilin homologs, including signal peptide peptidase, possess proteolytic activity without the need for other protein factors, and these simpler intramembrane aspartyl proteases have given insight into the action of presenilin within the γ-secretase complex. Cellular and molecular studies support a nine-transmembrane topology for presenilins and their homologs, and small-molecule inhibitors and cysteine scanning with crosslinking have suggested certain presenilin residues and regions that contribute to substrate recognition and handling. Identification of partial complexes has also offered clues to protein-protein interactions within the γ-secretase complex. Biophysical methods have allowed 3D views of the γ-secretase complex and presenilins. Most recently, the crystal structure of a microbial presenilin homolog has confirmed a nine-transmembrane topology and intramembranous location and proximity of the two conserved and essential aspartates. The crystal structure also provides a platform for the formulation of specific hypotheses regarding substrate interaction and catalysis as well as the pathogenic mechanism of Alzheimer-causing presenilin mutations. This article is part of a Special Issue entitled: Intramembrane Proteases.
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Affiliation(s)
- Michael S Wolfe
- Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, 77 Avenue Louis Pasteur, H.I.M. 754, Boston, MA 02115 USA.
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242
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Golde TE, Koo EH, Felsenstein KM, Osborne BA, Miele L. γ-Secretase inhibitors and modulators. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1828:2898-907. [PMID: 23791707 PMCID: PMC3857966 DOI: 10.1016/j.bbamem.2013.06.005] [Citation(s) in RCA: 215] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 06/04/2013] [Indexed: 12/11/2022]
Abstract
γ-Secretase is a fascinating, multi-subunit, intramembrane cleaving protease that is now being considered as a therapeutic target for a number of diseases. Potent, orally bioavailable γ-secretase inhibitors (GSIs) have been developed and tested in humans with Alzheimer's disease (AD) and cancer. Preclinical studies also suggest the therapeutic potential for GSIs in other disease conditions. However, due to inherent mechanism based-toxicity of non-selective inhibition of γ-secretase, clinical development of GSIs will require empirical testing with careful evaluation of benefit versus risk. In addition to GSIs, compounds referred to as γ-secretase modulators (GSMs) remain in development as AD therapeutics. GSMs do not inhibit γ-secretase, but modulate γ-secretase processivity and thereby shift the profile of the secreted amyloid β peptides (Aβ) peptides produced. Although GSMs are thought to have an inherently safe mechanism of action, their effects on substrates other than the amyloid β protein precursor (APP) have not been extensively investigated. Herein, we will review the current state of development of GSIs and GSMs and explore pertinent biological and pharmacological questions pertaining to the use of these agents for select indications. This article is part of a Special Issue entitled: Intramembrane Proteases.
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Affiliation(s)
- Todd E Golde
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA.
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243
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p53 in neurodegenerative diseases and brain cancers. Pharmacol Ther 2013; 142:99-113. [PMID: 24287312 DOI: 10.1016/j.pharmthera.2013.11.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 11/07/2013] [Indexed: 12/21/2022]
Abstract
More than thirty years elapsed since a protein, not yet called p53 at the time, was detected to bind SV40 during viral infection. Thousands of papers later, p53 evolved as the main tumor suppressor involved in growth arrest and apoptosis. A lot has been done but the protein has not yet revealed all its secrets. Particularly important is the observation that in totally distinct pathologies where apoptosis is either exacerbated or impaired, p53 appears to play a central role. This is exemplified for Alzheimer's and Parkinson's diseases that represent the two main causes of age-related neurodegenerative affections, where cell death enhancement appears as one of the main etiological paradigms. Conversely, in cancers, about half of the cases are linked to mutations in p53 leading to the impairment of p53-dependent apoptosis. The involvement of p53 in these pathologies has driven a huge amount of studies aimed at designing chemical tools or biological approaches to rescue p53 defects or over-activity. Here, we describe the data linking p53 to neurodegenerative diseases and brain cancers, and we document the various strategies to interfere with p53 dysfunctions in these disorders.
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244
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Trafficking in neurons: Searching for new targets for Alzheimer's disease future therapies. Eur J Pharmacol 2013; 719:84-106. [DOI: 10.1016/j.ejphar.2013.07.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 07/11/2013] [Indexed: 11/22/2022]
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245
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Peltonen HM, Haapasalo A, Hiltunen M, Kataja V, Kosma VM, Mannermaa A. Γ-secretase components as predictors of breast cancer outcome. PLoS One 2013; 8:e79249. [PMID: 24223915 PMCID: PMC3815159 DOI: 10.1371/journal.pone.0079249] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 09/19/2013] [Indexed: 12/26/2022] Open
Abstract
γ-secretase is a large ubiquitously expressed protease complex composed of four core subunits: presenilin, Aph1, PEN-2, and nicastrin. The function of γ-secretase in the cells is to proteolytically cleave various proteins within their transmembrane domains. Presenilin and Aph1 occur as alternative variants belonging to mutually exclusive γ-secretase complexes and providing the complexes with heterogeneous biochemical and physiological properties. γ-secretase is proposed to have a role in the development and progression of cancer and γ-secretase inhibitors are intensively studied for their probable anti-tumor effects in various types of cancer models. Here, we for the first time determined mRNA expression levels of presenilin-1, presenilin-2, Aph1a, Aph1b, PEN-2, and nicastrin in a set of breast cancer tissue samples (N = 55) by quantitative real-time PCR in order to clarify the clinical significance of the expression of different γ-secretase complex components in breast cancer. We found a high positive correlation between the subunit expression levels implying a common regulation of transcription. Our univariate Kaplan-Meier survival analyses established low expression level of γ-secretase complex as a risk factor for breast cancer specific mortality. The tumors expressing low levels of γ-secretase complex were characterized by high histopathological tumor grade, low or no expression of estrogen and progesterone receptors and consequently high probability to fall into the class of triple negative breast cancer tumors. These results may provide novel tools to further categorize breast cancer tumors, especially the highly aggressive and poorly treatable breast cancer type of triple negative cases, and suggest a significant role for γ-secretase in breast cancer.
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Affiliation(s)
- Hanna M. Peltonen
- Institute of Clinical Medicine, Pathology and Forensic Medicine, University of Eastern Finland, Kuopio, Finland
- Biocenter Kuopio and Cancer Center of Eastern Finland, University of Eastern Finland, Kuopio, Finland
- Imaging Center, Clinical Pathology, Kuopio University Hospital, Kuopio, Finland
- * E-mail:
| | - Annakaisa Haapasalo
- Institute of Clinical Medicine – Neurology, University of Eastern Finland, Kuopio, Finland
| | - Mikko Hiltunen
- Institute of Clinical Medicine – Neurology, University of Eastern Finland, Kuopio, Finland
| | - Vesa Kataja
- Institute of Clinical Medicine, Oncology, University of Eastern Finland, Kuopio, Finland
- Cancer Center, Kuopio University Hospital, Kuopio, Finland
| | - Veli-Matti Kosma
- Institute of Clinical Medicine, Pathology and Forensic Medicine, University of Eastern Finland, Kuopio, Finland
- Biocenter Kuopio and Cancer Center of Eastern Finland, University of Eastern Finland, Kuopio, Finland
- Imaging Center, Clinical Pathology, Kuopio University Hospital, Kuopio, Finland
| | - Arto Mannermaa
- Institute of Clinical Medicine, Pathology and Forensic Medicine, University of Eastern Finland, Kuopio, Finland
- Biocenter Kuopio and Cancer Center of Eastern Finland, University of Eastern Finland, Kuopio, Finland
- Imaging Center, Clinical Pathology, Kuopio University Hospital, Kuopio, Finland
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246
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Ye X, Tai W, Bao X, Chen X, Zhang D. FLZ inhibited γ-secretase selectively and decreased Aβ mitochondrial production in APP-SH-SY5Y cells. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2013; 387:75-85. [PMID: 24071813 DOI: 10.1007/s00210-013-0918-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 09/08/2013] [Indexed: 10/26/2022]
Abstract
Amyloid precursor protein (APP) metabolism is a key factor in the pathogenesis of Alzheimer's disease (AD). Amyloid-beta (Aβ) in mitochondria comes from APP mitochondrial metabolism or from the uptake Aβ from outside of mitochondria. It has been recently proposed that mitochondria are involved in the biochemical pathways through which Aβ causes neuronal dysfunction. The accumulated Aβ in mitochondria decreases the level of cytochrome c oxidase (COX IV) and attenuates the ATP production consequently. FLZ is a synthetic cyclic derivative of squamosamide from Annona glabra. In this study, the effect of FLZ on APP processing in mitochondria was investigated in SH-SY5Y cells over-expressing APP695 (wt/Swe). FLZ treatment attenuated APP processing and decreased Aβ production in mitochondria. The mitochondrial function was increased with the upregulation of COX IV both at protein and activity levels. ATP production was also increased after FLZ treatment. The mechanistic study showed that FLZ inhibited γ-secretase activity by decreasing C-terminal fragment protein level of presenilin, the active center of γ-secretase. The effect of FLZ differs from DAPT (a non-selective γ-secretase inhibitor), suggesting FLZ is a selective γ-secretase inhibitor. FLZ selectively inhibited γ-secretase in the cleavage of recombinant C terminus of APP in vitro, without specifically modulating the processing of recombinant Notch intracellular domain. These results indicate that FLZ decreases Aβ accumulation in mitochondria by selectively inhibiting γ-secretase. We propose that FLZ is a potential anti-AD drug candidate, and its mechanism may be improving mitochondrial function by reducing the Aβ burden in mitochondria.
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Affiliation(s)
- Xuan Ye
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, 1 Xian Nong Tan Street, Beijing, 100050, People's Republic of China
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247
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Kitazume S, Yoshihisa A, Yamaki T, Oikawa M, Tachida Y, Ogawa K, Imamaki R, Takeishi Y, Yamamoto N, Taniguchi N. Soluble amyloid precursor protein 770 is a novel biomarker candidate for acute coronary syndrome. Proteomics Clin Appl 2013; 7:657-63. [PMID: 23857744 DOI: 10.1002/prca.201200135] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 03/08/2013] [Accepted: 04/16/2013] [Indexed: 01/02/2023]
Abstract
Most Alzheimer disease patients show deposition of amyloid β (Aβ) peptide in blood vessels as well as the brain parenchyma. We previously found that vascular endothelial cells express amyloid β precursor protein (APP) 770, a different APP isoform from neuronal APP695, and that they produce amyloid β peptide. We analyzed the glycosylation of APP770 and found that O-glycosylated sAPP770 is preferentially processed by proteases for Aβ production. Because the soluble APP cleavage product sAPP is considered to be a possible marker for Alzheimer disease diagnosis, sAPP, consisting of a mixture of these variants, has been widely measured. We hypothesized that measurement of the endothelial APP770 cleavage product in patients separately from that of neuronal APP695 would enable us to discriminate between endothelial and neurological dysfunctions. Our recent findings, showing that the level of plasma sAPP770 is significantly higher in patients with acute coronary syndrome, raise the possibility that sAPP770 could be an indicator of endothelial dysfunction. In this review, we first describe the expression, glycosylation, and processing of APP770, and then discuss sAPP770 as a novel biomarker candidate of acute coronary syndrome.
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Affiliation(s)
- Shinobu Kitazume
- Disease Glycomics Team, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Wako, Saitama, Japan.
| | - Akiomi Yoshihisa
- Department of Advanced Cardiac Therapeutics, Cardiology and Hematology, Fukushima Medical University, Fukushima, Japan
| | - Takayoshi Yamaki
- Department of Advanced Cardiac Therapeutics, Cardiology and Hematology, Fukushima Medical University, Fukushima, Japan
| | - Masayoshi Oikawa
- Department of Advanced Cardiac Therapeutics, Cardiology and Hematology, Fukushima Medical University, Fukushima, Japan
| | - Yuriko Tachida
- Disease Glycomics Team, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Wako, Saitama, Japan
| | - Kazuko Ogawa
- Disease Glycomics Team, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Wako, Saitama, Japan
| | - Rie Imamaki
- Disease Glycomics Team, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Wako, Saitama, Japan
| | - Yasuchika Takeishi
- Department of Advanced Cardiac Therapeutics, Cardiology and Hematology, Fukushima Medical University, Fukushima, Japan
| | - Naomasa Yamamoto
- Department of Biochemistry, School of Pharmaceutical Sciences, Ohu University, Tomita, Koriyama, Fukushima, Japan
| | - Naoyuki Taniguchi
- Disease Glycomics Team, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Wako, Saitama, Japan
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248
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Nagai N, Ito Y. Excessive hydrogen peroxide enhances the attachment of amyloid β1-42 in the lens epithelium of UPL rats, a hereditary model for cataracts. Toxicology 2013; 315:55-64. [PMID: 23941810 DOI: 10.1016/j.tox.2013.08.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 08/03/2013] [Accepted: 08/03/2013] [Indexed: 01/09/2023]
Abstract
Several studies have reported that hydrogen peroxide (H2O2) is related to the toxicity of amyloid β (Aβ), and that the accumulation of Aβ in the lenses of humans causes lens opacification. In this study, we investigate the accumulation of Aβ1-42 in the lenses of UPL rats, which then leads to lens opacification. In addition, we demonstrate the effect of disulfiram eye drops (DSF), a potent radical scavenger, on Aβ1-42 accumulation in the lenses of UPL rats. The H2O2 levels in 46- to 60-day-old UPL rat lenses are significantly higher than in normal rats, and the Aβ1-42 levels in 53- and 60-day-old UPL rats are also increased only in lens epithelium containing capsules (capsule-epithelium), not in the lens cortex and nucleus. However, no increases in amyloid precursor protein (APP), β- or γ-secretase mRNA were observed in lenses of the corresponding ages. It has been thought that Aβ1-42 that accumulates in the lenses of UPL rats is actually produced in another tissue containing neuronal cells, such as brain or retina. Aβ1-42 levels in the brain and retina rise with aging, and the levels of APP, β- and γ-secretase mRNA in the retinas of 53-day-old UPL rats with opaque lenses are significantly higher than in 25-day-old UPL rats with transparent lenses. In contrast to the results in retinas, the levels of APP, β- and γ-secretase mRNA in the brains of 25- and 53-day-old UPL rats are similar. On the other hand, in an in vitro study, Aβ1-42 attachment in the lens capsule-epithelium of UPL rats was found to increase in H2O2. In addition, in an in vivo study, the inhibition of H2O2 by DSF was found to attenuate the increase in Aβ1-42 in the lens capsule-epithelium of 60-day-old UPL rats. Taken together, we hypothesize that excessive H2O2 in the lens enhances the attachment of Aβ1-42 in the lens capsule-epithelium of UPL rats, and that the instillation of DSF has the ability to attenuate the attachment of Aβ1-42 by inhibiting H2O2 production in lens. These findings provide significant information that can be used to design further studies aimed at developing anti-cataract drugs.
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Affiliation(s)
- Noriaki Nagai
- Faculty of Pharmacy, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan
| | - Yoshimasa Ito
- Faculty of Pharmacy, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan.
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249
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Fukuzaki Y, Sugawara H, Yamanoha B, Kogure S. 532 nm low-power laser irradiation recovers γ-secretase inhibitor-mediated cell growth suppression and promotes cell proliferation via Akt signaling. PLoS One 2013; 8:e70737. [PMID: 23950991 PMCID: PMC3737144 DOI: 10.1371/journal.pone.0070737] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 06/27/2013] [Indexed: 02/03/2023] Open
Abstract
Background and Objective The γ-secretase inhibitor (GSI) has been shown to inhibit expression of amyloid beta (Aβ), but GSI also has a side effect of reducing cell survival. Since low-power laser irradiation (LLI) has been known to promote cell survival, we examined whether 532 nm LLI can rescue the GSI side effect or not. Study Design/Materials and Methods The human-derived glioblastoma cells (A-172) were cultured in 35 mm culture dishes or 96-well plate. The center of dish or selected wells was irradiated with 532 nm laser (Nd:YVO4, CW, 60 mW) for 20, 40 and 60 min, respectively. The irradiated cells were photographed at immediately after, 24 and 48 h later and counted. GSI was supplemented in medium 3 h before LLI. The MTT assay was also used to estimate viable cells at 48 h after irradiation. The expression of phosphorylated Akt (p-Akt) or phosphorylated PTEN (p-PTEN) was examined by immunofluorescent staining and measured by fluorescence intensity using the software (BZ-9000, KEYENCE, Japan). Results GSI application depressed cell proliferation as well as cell survival compared to control. GSI down-regulated Aβ but up-regulated p-PTEN and suppressed p-Akt. Application of 532 nm LLI in the presence of GSI significantly recovered the GSI-mediated effects, i.e., LLI could decrease elevated p-PTEN, while increased p-Akt expression with keeping Aβ suppression. The LLI effects had a dose-dependency. Conclusion We confirmed that GSI potently suppressed intracellular Aβ and decreased cell survival. We conclude that a combination of GSI application and 532 nm LLI can increase cell proliferation via Akt activation while keeping PTEN and Aβ suppressed.
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Affiliation(s)
- Yumi Fukuzaki
- Department of Bioinformatics, Graduate School of Engineering, Soka University, Hachioji, Tokyo, Japan
| | - Haruna Sugawara
- Department of Bioinformatics, Graduate School of Engineering, Soka University, Hachioji, Tokyo, Japan
| | - Banri Yamanoha
- Department of Environmental Engineering for Symbiosis, Faculty of Engineering, Soka University, Hachioji, Tokyo, Japan
| | - Shinichi Kogure
- Department of Bioinformatics, Graduate School of Engineering, Soka University, Hachioji, Tokyo, Japan
- * E-mail:
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250
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Zhang S, Zhang M, Cai F, Song W. Biological function of Presenilin and its role in AD pathogenesis. Transl Neurodegener 2013; 2:15. [PMID: 23866842 PMCID: PMC3718700 DOI: 10.1186/2047-9158-2-15] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Accepted: 07/14/2013] [Indexed: 01/06/2023] Open
Abstract
Presenilins (PSs) are the catalytic core of γ-secretase complex. However, the mechanism of FAD-associated PS mutations in AD pathogenesis still remains elusive. Here we review the general biology and mechanism of γ-secretase and focus on the catalytic components – presenilins and their biological functions and contributions to the AD pathogenesis. The functions of presenilins are divided into γ-secretase dependent and γ-secretase independent ones. The γ-secretase dependent functions of presenilins are exemplified by the sequential cleavages in the processing of APP and Notch; the γ-secretase independent functions of presenilins include stabilizing β-catenin in Wnt signaling pathway, regulating calcium homeostasis and their interaction with synaptic transmission.
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Affiliation(s)
- Shuting Zhang
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, Graduate Program in Neuroscience, The University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada.
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