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Lu L, Hong W. From endosomes to the trans-Golgi network. Semin Cell Dev Biol 2014; 31:30-9. [PMID: 24769370 DOI: 10.1016/j.semcdb.2014.04.024] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 04/16/2014] [Accepted: 04/16/2014] [Indexed: 12/11/2022]
Abstract
The retrograde trafficking from endosomes to the trans-Golgi network (TGN) is one of the major endocytic pathways to divert proteins and lipids away from lysosomal degradation. Retrograde transported cargos enter the TGN via two itineraries from either the early endosome/recycling endosome or the late endosome and involve various machinery components such as retromer, sorting nexins, clathrin, small GTPases, tethering factors and SNAREs. Recently, the pathway has been recognized for its role in signal transduction, physiology and pathogenesis of human diseases.
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Affiliation(s)
- Lei Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
| | - Wanjin Hong
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore; School of Pharmaceutical Sciences, Xiamen University, Xiamen, People's Republic of China
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102
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Evidence of a novel mechanism for partial γ-secretase inhibition induced paradoxical increase in secreted amyloid β protein. PLoS One 2014; 9:e91531. [PMID: 24658363 PMCID: PMC3962361 DOI: 10.1371/journal.pone.0091531] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 02/12/2014] [Indexed: 02/02/2023] Open
Abstract
BACE1 (β-secretase) and α-secretase cleave the Alzheimer's amyloid β protein (Aβ) precursor (APP) to C-terminal fragments of 99 aa (CTFβ) and 83 aa (CTFα), respectively, which are further cleaved by γ-secretase to eventually secrete Aβ and Aα (a.k.a. P3) that terminate predominantly at residues 40 and 42. A number of γ-secretase inhibitors (GSIs), such as N-[N-(3,5-Difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester (DAPT), have been developed with the goal of reducing Aβ to treat Alzheimer's disease (AD). Although most studies show that DAPT inhibits Aβ in a dose-dependent manner several studies have also detected a biphasic effect with an unexpected increase at low doses of DAPT in cell cultures, animal models and clinical trials. In this article, we confirm the increase in Aβ40 and Aβ42 in SH-SY5Y human neuroblastoma cells treated with low doses of DAPT and identify one of the mechanisms for this paradox. We studied the pathway by first demonstrating that stimulation of Aβ, a product of γ-secretase, was accompanied by a parallel increase of its substrate CTFβ, thereby demonstrating that the inhibitor was not anomalously stimulating enzyme activity at low levels. Secondly, we have demonstrated that inhibition of an Aβ degrading activity, endothelin converting enzyme (ECE), yielded more Aβ, but abolished the DAPT-induced stimulation. Finally, we have demonstrated that Aα, which is generated in the secretory pathway before endocytosis, is not subject to the DAPT-mediated stimulation. We therefore conclude that impairment of γ-secretase can paradoxically increase Aβ by transiently skirting Aβ degradation in the endosome. This study adds to the growing body of literature suggesting that preserving γ-secretase activity, rather than inhibiting it, is important for prevention of neurodegeneration.
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103
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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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104
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Buggia-Prévot V, Fernandez CG, Riordan S, Vetrivel KS, Roseman J, Waters J, Bindokas VP, Vassar R, Thinakaran G. Axonal BACE1 dynamics and targeting in hippocampal neurons: a role for Rab11 GTPase. Mol Neurodegener 2014; 9:1. [PMID: 24386896 PMCID: PMC4031619 DOI: 10.1186/1750-1326-9-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 12/22/2013] [Indexed: 01/22/2023] Open
Abstract
Background BACE1 is one of the two enzymes that cleave amyloid precursor protein to generate Alzheimer's disease (AD) beta amyloid peptides. It is widely believed that BACE1 initiates APP processing in endosomes, and in the brain this cleavage is known to occur during axonal transport of APP. In addition, BACE1 accumulates in dystrophic neurites surrounding brain senile plaques in individuals with AD, suggesting that abnormal accumulation of BACE1 at presynaptic terminals contributes to pathogenesis in AD. However, only limited information is available on BACE1 axonal transport and targeting. Results By visualizing BACE1-YFP dynamics using live imaging, we demonstrate that BACE1 undergoes bi-directional transport in dynamic tubulo-vesicular carriers along axons in cultured hippocampal neurons and in acute hippocampal slices of transgenic mice. In addition, a subset of BACE1 is present in larger stationary structures, which are active presynaptic sites. In cultured neurons, BACE1-YFP is preferentially targeted to axons over time, consistent with predominant in vivo localization of BACE1 in presynaptic terminals. Confocal analysis and dual-color live imaging revealed a localization and dynamic transport of BACE1 along dendrites and axons in Rab11-positive recycling endosomes. Impairment of Rab11 function leads to a diminution of total and endocytosed BACE1 in axons, concomitant with an increase in the soma. Together, these results suggest that BACE1 is sorted to axons in endosomes in a Rab11-dependent manner. Conclusion Our results reveal novel information on dynamic BACE1 transport in neurons, and demonstrate that Rab11-GTPase function is critical for axonal sorting of BACE1. Thus, we suggest that BACE1 transcytosis in endosomes contributes to presynaptic BACE1 localization.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Gopal Thinakaran
- Department of Neurobiology, The University of Chicago, Chicago, IL 60637, USA.
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105
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Buggia-Prévot V, Fernandez CG, Udayar V, Vetrivel KS, Elie A, Roseman J, Sasse VA, Lefkow M, Meckler X, Bhattacharyya S, George M, Kar S, Bindokas VP, Parent AT, Rajendran L, Band H, Vassar R, Thinakaran G. A function for EHD family proteins in unidirectional retrograde dendritic transport of BACE1 and Alzheimer's disease Aβ production. Cell Rep 2013; 5:1552-63. [PMID: 24373286 PMCID: PMC3932704 DOI: 10.1016/j.celrep.2013.12.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 11/07/2013] [Accepted: 12/03/2013] [Indexed: 11/22/2022] Open
Abstract
Abnormal accumulation of β-secretase (BACE1) in dystrophic neurites and presynaptic β-amyloid (Aβ) production contribute to Alzheimer's disease pathogenesis. Little, however, is known about BACE1 sorting and dynamic transport in neurons. We investigated BACE1 trafficking in hippocampal neurons using live-cell imaging and selective labeling. We report that transport vesicles containing internalized BACE1 in dendrites undergo exclusive retrograde transport toward the soma, whereas they undergo bidirectional transport in axons. Unidirectional dendritic transport requires Eps15-homology-domain-containing (EHD) 1 and 3 protein function. Furthermore, loss of EHD function compromises dynamic axonal transport and overall BACE1 levels in axons. EHD1/3 colocalize with BACE1 and APP β-C-terminal fragments in hippocampal mossy fiber terminals, and their depletion in neurons significantly attenuates Aβ levels. These results demonstrate unidirectional endocytic transport of a dendritic cargo and reveal a role for EHD proteins in neuronal BACE1 transcytosis and Aβ production, processes that are highly relevant for Alzheimer's disease.
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Affiliation(s)
- Virginie Buggia-Prévot
- Departments of Neurobiology, Neurology, and Pathology, The University of Chicago, Chicago, IL 60637, USA
| | - Celia G Fernandez
- Committee on Neurobiology, The University of Chicago, Chicago, IL 60637, USA
| | - Vinod Udayar
- Systems and Cell Biology of Neurodegeneration, Division of Psychiatry Research, University of Zurich, 8008 Zurich, Switzerland
| | - Kulandaivelu S Vetrivel
- Departments of Neurobiology, Neurology, and Pathology, The University of Chicago, Chicago, IL 60637, USA
| | - Aureliane Elie
- Departments of Neurobiology, Neurology, and Pathology, The University of Chicago, Chicago, IL 60637, USA
| | - Jelita Roseman
- Departments of Neurobiology, Neurology, and Pathology, The University of Chicago, Chicago, IL 60637, USA
| | - Verena A Sasse
- Centre for Prions and Protein Folding Diseases, Departments of Medicine and Psychiatry, University of Alberta, Edmonton, AB T6G 2M8, Canada
| | - Margaret Lefkow
- Committee on Neurobiology, The University of Chicago, Chicago, IL 60637, USA
| | - Xavier Meckler
- Departments of Neurobiology, Neurology, and Pathology, The University of Chicago, Chicago, IL 60637, USA
| | - Sohinee Bhattacharyya
- Eppley Institute for Research in Cancer and Allied Diseases and Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Manju George
- Eppley Institute for Research in Cancer and Allied Diseases and Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Satyabrata Kar
- Centre for Prions and Protein Folding Diseases, Departments of Medicine and Psychiatry, University of Alberta, Edmonton, AB T6G 2M8, Canada
| | - Vytautas P Bindokas
- Department of Pharmacological and Physiological Sciences, The University of Chicago, Chicago, IL 60637, USA
| | - Angèle T Parent
- Departments of Neurobiology, Neurology, and Pathology, The University of Chicago, Chicago, IL 60637, USA
| | - Lawrence Rajendran
- Systems and Cell Biology of Neurodegeneration, Division of Psychiatry Research, University of Zurich, 8008 Zurich, Switzerland
| | - Hamid Band
- Eppley Institute for Research in Cancer and Allied Diseases and Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Robert Vassar
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Gopal Thinakaran
- Departments of Neurobiology, Neurology, and Pathology, The University of Chicago, Chicago, IL 60637, USA; Committee on Neurobiology, The University of Chicago, Chicago, IL 60637, USA.
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