101
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Meckler X, Checler F. Presenilin 1 and Presenilin 2 Target γ-Secretase Complexes to Distinct Cellular Compartments. J Biol Chem 2016; 291:12821-12837. [PMID: 27059953 DOI: 10.1074/jbc.m115.708297] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Indexed: 11/06/2022] Open
Abstract
γ-Secretase complexes achieve the production of amyloid peptides playing a key role in Alzheimer disease. These proteases have many substrates involved in important physiological functions. They are composed of two constant subunits, nicastrin and PEN2, and two variable ones, presenilin (PS1 or PS2) and APH1 (APH1aL, APH1aS, or APH1b). Whether the composition of a given γ-secretase complex determines a specific cellular targeting remains unsolved. Here we combined a bidirectional inducible promoter and 2A peptide technology to generate constructs for the temporary, stoichiometric co-expression of six different combinations of the four γ-secretase subunits including EGFP-tagged nicastrin. These plasmids allow for the formation of functional γ-secretase complexes displaying specific activities and maturations. We show that PS1-containing γ-secretase complexes were targeted to the plasma membrane, whereas PS2-containing ones were addressed to the trans-Golgi network, to recycling endosomes, and, depending on the APH1-variant, to late endocytic compartments. Overall, these novel constructs unravel a presenilin-dependent subcellular targeting of γ-secretase complexes. These tools should prove useful to determine whether the cellular distribution of γ-secretase complexes contributes to substrate selectivity and to delineate regulations of their trafficking.
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Affiliation(s)
- Xavier Meckler
- From the Université de Nice Sophia-Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire CNRS UMR7275, Laboratoire d'Excellence Distalz, Sophia-Antipolis, 06560 Valbonne, France
| | - Frédéric Checler
- From the Université de Nice Sophia-Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire CNRS UMR7275, Laboratoire d'Excellence Distalz, Sophia-Antipolis, 06560 Valbonne, France.
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102
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Diabetes Mellitus Induces Alzheimer's Disease Pathology: Histopathological Evidence from Animal Models. Int J Mol Sci 2016; 17:503. [PMID: 27058526 PMCID: PMC4848959 DOI: 10.3390/ijms17040503] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 03/25/2016] [Accepted: 03/30/2016] [Indexed: 01/07/2023] Open
Abstract
Alzheimer’s disease (AD) is the major causative disease of dementia and is characterized pathologically by the accumulation of senile plaques (SPs) and neurofibrillary tangles (NFTs) in the brain. Although genetic studies show that β-amyloid protein (Aβ), the major component of SPs, is the key factor underlying AD pathogenesis, it remains unclear why advanced age often leads to AD. Interestingly, several epidemiological and clinical studies show that type II diabetes mellitus (DM) patients are more likely to exhibit increased susceptibility to AD. Moreover, growing evidence suggests that there are several connections between the neuropathology that underlies AD and DM, and there is evidence that the experimental induction of DM can cause cognitive dysfunction, even in rodent animal models. This mini-review summarizes histopathological evidence that DM induces AD pathology in animal models and discusses the possibility that aberrant insulin signaling is a key factor in the induction of AD pathology.
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103
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Dries DR, Zhu Y, Brooks MM, Forero DA, Adachi M, Cenik B, West JM, Han YH, Yu C, Arbella J, Nordin A, Adolfsson R, Del-Favero J, Lu QR, Callaerts P, Birnbaum SG, Yu G. Loss of Nicastrin from Oligodendrocytes Results in Hypomyelination and Schizophrenia with Compulsive Behavior. J Biol Chem 2016; 291:11647-56. [PMID: 27008863 DOI: 10.1074/jbc.m116.715078] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Indexed: 12/12/2022] Open
Abstract
The biological underpinnings and the pathological lesions of psychiatric disorders are centuries-old questions that have yet to be understood. Recent studies suggest that schizophrenia and related disorders likely have their origins in perturbed neurodevelopment and can result from a large number of common genetic variants or multiple, individually rare genetic alterations. It is thus conceivable that key neurodevelopmental pathways underline the various genetic changes and the still unknown pathological lesions in schizophrenia. Here, we report that mice defective of the nicastrin subunit of γ-secretase in oligodendrocytes have hypomyelination in the central nervous system. These mice have altered dopamine signaling and display profound abnormal phenotypes reminiscent of schizophrenia. In addition, we identify an association of the nicastrin gene with a human schizophrenia cohort. These observations implicate γ-secretase and its mediated neurodevelopmental pathways in schizophrenia and provide support for the "myelination hypothesis" of the disease. Moreover, by showing that schizophrenia and obsessive-compulsive symptoms could be modeled in animals wherein a single genetic factor is altered, our work provides a biological basis that schizophrenia with obsessive-compulsive disorder is a distinct subtype of schizophrenia.
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Affiliation(s)
- Daniel R Dries
- From the Departments of Neuroscience, the Chemistry Department, Juniata College, Huntingdon, Pennsylvania 16652
| | - Yi Zhu
- From the Departments of Neuroscience
| | | | - Diego A Forero
- the Laboratory of NeuroPsychiatric Genetics, Biomedical Sciences Research Group, School of Medicine, Universidad Antonio Nariño, 37-94 Bogotá, Colombia
| | | | | | | | | | - Cong Yu
- From the Departments of Neuroscience
| | - Jennifer Arbella
- the Chemistry Department, Juniata College, Huntingdon, Pennsylvania 16652
| | - Annelie Nordin
- the Division of Psychiatry, Department of Clinical Sciences, Umea University, SE-901 87 Umea, Sweden
| | - Rolf Adolfsson
- the Division of Psychiatry, Department of Clinical Sciences, Umea University, SE-901 87 Umea, Sweden
| | - Jurgen Del-Favero
- the Applied Molecular Genomics Unit, VIB Department of Molecular Genetics, University of Antwerp, 2610 Antwerp, Belgium
| | - Q Richard Lu
- the Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, and Developmental Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Patrick Callaerts
- the Laboratory of Behavioral and Developmental Genetics, Katholieke Universiteit Leuven Center for Human Genetics, VIB Center for the Biology of Disease, 3000 Leuven, Belgium
| | | | - Gang Yu
- From the Departments of Neuroscience,
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104
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Ochiishi T, Doi M, Yamasaki K, Hirose K, Kitamura A, Urabe T, Hattori N, Kinjo M, Ebihara T, Shimura H. Development of new fusion proteins for visualizing amyloid-β oligomers in vivo. Sci Rep 2016; 6:22712. [PMID: 26982553 PMCID: PMC4793674 DOI: 10.1038/srep22712] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/18/2016] [Indexed: 12/30/2022] Open
Abstract
The intracellular accumulation of amyloid-β (Aβ) oligomers critically contributes to disease progression in Alzheimer’s disease (AD) and can be the potential target of AD therapy. Direct observation of molecular dynamics of Aβ oligomers in vivo is key for drug discovery research, however, it has been challenging because Aβ aggregation inhibits the fluorescence from fusion proteins. Here, we developed Aβ1-42-GFP fusion proteins that are oligomerized and visualize their dynamics inside cells even when aggregated. We examined the aggregation states of Aβ-GFP fusion proteins using several methods and confirmed that they did not assemble into fibrils, but instead formed oligomers in vitro and in live cells. By arranging the length of the liker between Aβ and GFP, we generated two fusion proteins with “a long-linker” and “a short-linker”, and revealed that the aggregation property of fusion proteins can be evaluated by measuring fluorescence intensities using rat primary culture neurons transfected with Aβ-GFP plasmids and Aβ-GFP transgenic C. elegans. We found that Aβ-GFP fusion proteins induced cell death in COS7 cells. These results suggested that novel Aβ-GFP fusion proteins could be utilized for studying the physiological functions of Aβ oligomers in living cells and animals, and for drug screening by analyzing Aβ toxicity.
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Affiliation(s)
- Tomoyo Ochiishi
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Motomichi Doi
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Kazuhiko Yamasaki
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Keiko Hirose
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Akira Kitamura
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan
| | - Takao Urabe
- Department of Neurology, Juntendo University Urayasu Hospital, 2-1-1, Tomioka, Urayasu, Chiba 279-0021, Japan
| | - Nobutaka Hattori
- Department of Neurology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Masataka Kinjo
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan
| | - Tatsuhiko Ebihara
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Hideki Shimura
- Department of Neurology, Juntendo University Urayasu Hospital, 2-1-1, Tomioka, Urayasu, Chiba 279-0021, Japan
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105
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Ochiishi T, Doi M, Yamasaki K, Hirose K, Kitamura A, Urabe T, Hattori N, Kinjo M, Ebihara T, Shimura H. Development of new fusion proteins for visualizing amyloid-β oligomers in vivo. Sci Rep 2016. [PMID: 26982553 DOI: 10.1038/srep22712(2016)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The intracellular accumulation of amyloid-β (Aβ) oligomers critically contributes to disease progression in Alzheimer's disease (AD) and can be the potential target of AD therapy. Direct observation of molecular dynamics of Aβ oligomers in vivo is key for drug discovery research, however, it has been challenging because Aβ aggregation inhibits the fluorescence from fusion proteins. Here, we developed Aβ1-42-GFP fusion proteins that are oligomerized and visualize their dynamics inside cells even when aggregated. We examined the aggregation states of Aβ-GFP fusion proteins using several methods and confirmed that they did not assemble into fibrils, but instead formed oligomers in vitro and in live cells. By arranging the length of the liker between Aβ and GFP, we generated two fusion proteins with "a long-linker" and "a short-linker", and revealed that the aggregation property of fusion proteins can be evaluated by measuring fluorescence intensities using rat primary culture neurons transfected with Aβ-GFP plasmids and Aβ-GFP transgenic C. elegans. We found that Aβ-GFP fusion proteins induced cell death in COS7 cells. These results suggested that novel Aβ-GFP fusion proteins could be utilized for studying the physiological functions of Aβ oligomers in living cells and animals, and for drug screening by analyzing Aβ toxicity.
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Affiliation(s)
- Tomoyo Ochiishi
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Motomichi Doi
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Kazuhiko Yamasaki
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Keiko Hirose
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Akira Kitamura
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan
| | - Takao Urabe
- Department of Neurology, Juntendo University Urayasu Hospital, 2-1-1, Tomioka, Urayasu, Chiba 279-0021, Japan
| | - Nobutaka Hattori
- Department of Neurology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Masataka Kinjo
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan
| | - Tatsuhiko Ebihara
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Hideki Shimura
- Department of Neurology, Juntendo University Urayasu Hospital, 2-1-1, Tomioka, Urayasu, Chiba 279-0021, Japan
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106
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Li N, Liu K, Qiu Y, Ren Z, Dai R, Deng Y, Qing H. Effect of Presenilin Mutations on APP Cleavage; Insights into the Pathogenesis of FAD. Front Aging Neurosci 2016; 8:51. [PMID: 27014058 PMCID: PMC4786568 DOI: 10.3389/fnagi.2016.00051] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 02/26/2016] [Indexed: 11/13/2022] Open
Abstract
Alzheimer disease (AD) is characterized by progressive memory loss, reduction in cognitive functions, and damage to the brain. The β-amyloid precursor protein can be sequentially cleaved by β- secretase and γ-secretase. Mutations in the presenilin1(PS1) are the most common cause of Familial Alzheimer’s disease (FAD). PS1 mutations can alter the activity of γ-secretase on the cleavage of the β-amyloid precursor protein, causing increased Aβ production. Previous studies show that the βAPP-C-terminal fragment is first cleaved by β-scretase, primarily generating long fragments of Aβ48 and Aβ49, followed by the stepwise cleavage of every three amino acid residues at the C terminus, resulting in Aβ48-, 45-, 42 line and Aβ49-, 46-, 43-, 40 line. Here, we used LC-MS/MS to analyze unique peptides IAT, VVIA, ITL, TVI, IVI through sequential cleavage, combined with ELISA to test the level of Aβ42 and Aβ40 for validation. The results show that most FAD mutant PS1 can alter the level of Aβ42 and Aβ40 monitored by the Aβ42/Aβ40 ratio. Among them, six mutants (I143T, H163P, S170F, Q223R, M233V, and G384A) affect the Aβ42/40 ratio through both Aβ49-40 and Aβ48-38 lines; L166P through decreasing the Aβ49-40 line, six mutants (I143V, M146V, G217A, E280A, L381V, and L392V) through increasing the Aβ48-42 line. More importantly, we found some mutations can affect the γ-secretase cleavage preference of α-CTF and β-CTF. In conclusion, we found that the FAD PS1 mutations mainly increase the generation of Aβ42 by decreasing the cleavage of Aβ42–Aβ38 and Aβ43–Aβ40.
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Affiliation(s)
- Nuomin Li
- School of Life Science, Beijing Institute of Technology Beijing, China
| | - Kefu Liu
- School of Life Science, Beijing Institute of Technology Beijing, China
| | - Yunjie Qiu
- School of Life Science, Beijing Institute of Technology Beijing, China
| | - Zehui Ren
- School of Life Science, Beijing Institute of Technology Beijing, China
| | - Rongji Dai
- School of Life Science, Beijing Institute of Technology Beijing, China
| | - Yulin Deng
- School of Life Science, Beijing Institute of Technology Beijing, China
| | - Hong Qing
- School of Life Science, Beijing Institute of Technology Beijing, China
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107
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Ueda N, Tomita T, Yanagisawa K, Kimura N. Retromer and Rab2-dependent trafficking mediate PS1 degradation by proteasomes in endocytic disturbance. J Neurochem 2016; 137:647-58. [PMID: 26896628 DOI: 10.1111/jnc.13586] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 01/21/2016] [Accepted: 02/09/2016] [Indexed: 12/21/2022]
Abstract
Accumulating evidence suggests that endocytic pathway deficits are involved in Alzheimer's disease pathogenesis. Several reports show that endocytic disturbance affects β-amyloid peptide (Aβ) cleavage from β-amyloid precursor protein (APP). Presenilin-1 (PS1) is the catalytic core of the γ-secretase complex required for Aβ generation. Previously, we showed that aging induces endocytic disturbance, resulting in the accumulation of Aβ and APP in enlarged endosomes. It remains unclear, however, whether PS1 localization and function are affected with endocytic disturbance. Here, we report that in endocytic disturbance, PS1 is transported from endosomes to ER/Golgi compartments via retromer trafficking, and that PS1 interacts with vacuolar protein sorting-associated protein 35 both in vitro and in vivo. Moreover, PS1 is degraded by proteasomes via a Rab2-dependent trafficking pathway, only during endocytic disturbance. These findings suggest that PS1 levels and localization in endosomes are regulated by retromer trafficking and ER-associated degradation system, even if endocytic disturbance significantly induces the endosomal accumulation of APP and β-site APP-cleaving enzyme 1. Results of this study also suggest that retromer deficiency can affect PS1 localization in endosomes, where Aβ cleavage mainly occurs, possibly leading to enhanced Aβ pathology. We proposed the following mechanism for intracellular transport of presenilin-1 (PS1). When endosome/lysosome trafficking is disturbed, PS1 is transported from endosome to endoplasmic reticulum (ER)/Golgi compartments via retromer and Rab2-mediated trafficking, and then degraded by endoplasmic reticulum-associated degradation (ERAD). Perturbations in this trafficking can cause abnormal endosomal accumulation of PS1, and then may lead to exacerbated Aβ pathology. Cover Image for this issue: doi: 10.1111/jnc.13318.
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Affiliation(s)
- Naoya Ueda
- Section of Cell Biology and Pathology, Department of Alzheimer's Disease Research, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology (NCGG), Aichi, Japan
| | - Taisuke Tomita
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Katsuhiko Yanagisawa
- Section of Cell Biology and Pathology, Department of Alzheimer's Disease Research, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology (NCGG), Aichi, Japan
| | - Nobuyuki Kimura
- Section of Cell Biology and Pathology, Department of Alzheimer's Disease Research, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology (NCGG), Aichi, Japan
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108
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Pisklakova A, Grigson E, Ozerova M, Chen F, Sullivan DM, Nefedova Y. Anti-myeloma effect of pharmacological inhibition of Notch/gamma-secretase with RO4929097 is mediated by modulation of tumor microenvironment. Cancer Biol Ther 2016; 17:477-85. [PMID: 26934342 DOI: 10.1080/15384047.2016.1156261] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Multiple myeloma (MM), a blood cancer characterized by the uncontrolled proliferation of plasma cells, remains incurable by current therapy. Notch signaling has been implicated in the growth and chemoresistance of various cancer types including MM, and therefore we hypothesized that targeting the Notch pathway could be beneficial for the treatment of this disease. Here, we report an anti-tumor effect of Notch/γ-secretase inhibitor RO4929097 in a pre-clinical model of MM. We demonstrate that this effect was associated with decreased angiogenesis and significant down-regulation of TGF-β1. In addition, we also show that treatment with RO4929097 results in decreased number and functional activity of osteoclasts. Taken together, our data indicate that targeting Notch may be considered as a new strategy to be tested for MM therapy.
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Affiliation(s)
| | - Eileen Grigson
- a H. Lee Moffitt Cancer Center and Research Institute , Tampa , FL , USA.,b The Wistar Institute , Philadelphia , PA , USA
| | - Maria Ozerova
- a H. Lee Moffitt Cancer Center and Research Institute , Tampa , FL , USA
| | - Feng Chen
- a H. Lee Moffitt Cancer Center and Research Institute , Tampa , FL , USA
| | - Daniel M Sullivan
- a H. Lee Moffitt Cancer Center and Research Institute , Tampa , FL , USA
| | - Yulia Nefedova
- a H. Lee Moffitt Cancer Center and Research Institute , Tampa , FL , USA.,b The Wistar Institute , Philadelphia , PA , USA
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109
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Li Y, Liew LSY, Li Q, Kang C. Structure of the transmembrane domain of human nicastrin-a component of γ-secretase. Sci Rep 2016; 6:19522. [PMID: 26776682 PMCID: PMC4726005 DOI: 10.1038/srep19522] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 12/09/2015] [Indexed: 02/04/2023] Open
Abstract
Nicastrin is the largest component of γ-secretase that is an intramembrane protease important in the development of Alzheimer's disease. Nicastrin contains a large extracellular domain, a single transmembrane (TM) domain, and a short C-terminus. Its TM domain is important for the γ-secretase complex formation. Here we report nuclear magnetic resonance (NMR) studies of the TM and C-terminal regions of human nicastrin in both sodium dodecyl sulfate (SDS) and dodecylphosphocholine (DPC) micelles. Structural study and dynamic analysis reveal that the TM domain is largely helical and stable under both SDS and DPC micelles with its N-terminal region undergoing intermediate time scale motion. The TM helix contains a hydrophilic patch that is important for TM-TM interactions. The short C-terminus is not structured in solution and a region formed by residues V697-A702 interacts with the membrane, suggesting that these residues may play a role in the γ-secretase complex formation. Our study provides structural insight into the function of the nicastrin TM domain and the C-terminus in γ-secretase complex.
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Affiliation(s)
- Yan Li
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR), Singapore, 138669 Singapore
| | - Lynette Sin Yee Liew
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR), Singapore, 138669 Singapore
| | - Qingxin Li
- Institute of Chemical &Engineering Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, 138669 Singapore
| | - CongBao Kang
- Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR), Singapore, 138669 Singapore
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110
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Nicastrin functions to sterically hinder γ-secretase-substrate interactions driven by substrate transmembrane domain. Proc Natl Acad Sci U S A 2015; 113:E509-18. [PMID: 26699478 DOI: 10.1073/pnas.1512952113] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
γ-Secretase is an intramembrane-cleaving protease that processes many type-I integral membrane proteins within the lipid bilayer, an event preceded by shedding of most of the substrate's ectodomain by α- or β-secretases. The mechanism by which γ-secretase selectively recognizes and recruits ectodomain-shed substrates for catalysis remains unclear. In contrast to previous reports that substrate is actively recruited for catalysis when its remaining short ectodomain interacts with the nicastrin component of γ-secretase, we find that substrate ectodomain is entirely dispensable for cleavage. Instead, γ-secretase-substrate binding is driven by an apparent tight-binding interaction derived from substrate transmembrane domain, a mechanism in stark contrast to rhomboid--another family of intramembrane-cleaving proteases. Disruption of the nicastrin fold allows for more efficient cleavage of substrates retaining longer ectodomains, indicating that nicastrin actively excludes larger substrates through steric hindrance, thus serving as a molecular gatekeeper for substrate binding and catalysis.
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111
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Sparling DP, Yu J, Kim K, Zhu C, Brachs S, Birkenfeld AL, Pajvani UB. Adipocyte-specific blockade of gamma-secretase, but not inhibition of Notch activity, reduces adipose insulin sensitivity. Mol Metab 2015; 5:113-121. [PMID: 26909319 PMCID: PMC4735659 DOI: 10.1016/j.molmet.2015.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 11/18/2015] [Accepted: 11/25/2015] [Indexed: 01/12/2023] Open
Abstract
Objective As the obesity pandemic continues to expand, novel molecular targets to reduce obesity-related insulin resistance and Type 2 Diabetes (T2D) continue to be needed. We have recently shown that obesity is associated with reactivated liver Notch signaling, which, in turn, increases hepatic insulin resistance, opening up therapeutic avenues for Notch inhibitors to be repurposed for T2D. Herein, we tested the systemic effects of γ-secretase inhibitors (GSIs), which prevent endogenous Notch activation, and confirmed these effects through creation and characterization of two different adipocyte-specific Notch loss-of-function mouse models through genetic ablation of the Notch transcriptional effector Rbp-Jk (A-Rbpj) and the obligate γ-secretase component Nicastrin (A-Nicastrin). Methods Glucose homeostasis and both local adipose and systemic insulin sensitivity were examined in GSI-treated, A-Rbpj and A-Nicastrin mice, as well as vehicle-treated or control littermates, with complementary in vitro studies in primary hepatocytes and 3T3-L1 adipocytes. Results GSI-treatment increases hepatic insulin sensitivity in obese mice but leads to reciprocal lowering of adipose glucose disposal. While A-Rbpj mice show normal body weight, adipose development and mass and unchanged adipose insulin sensitivity as control littermates, A-Nicastrin mice are relatively insulin-resistant, mirroring the GSI effect on adipose insulin action. Conclusions Notch signaling is dispensable for normal adipocyte function, but adipocyte-specific γ-secretase blockade reduces adipose insulin sensitivity, suggesting that specific Notch inhibitors would be preferable to GSIs for application in T2D. γ-secretase inhibitors (GSIs) are non-specific inhibitors of Notch signaling. GSI-treatment of obese mice increases hepatic, but lowers adipose insulin sensitivity. Adipocyte-specific Notch inhibition does not affect adipose mass or glucose homeostasis. Adipocyte-specific γ-secretase blockade reduces adipose insulin sensitivity. Specific Notch inhibitors may be preferable to GSIs for treatment of Type 2 Diabetes.
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Affiliation(s)
- David P Sparling
- Departments of Pediatrics, Columbia University, New York, NY 10032, USA
| | - Junjie Yu
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - KyeongJin Kim
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Changyu Zhu
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Sebastian Brachs
- Department of Endocrinology, Diabetes and Nutrition, Center for Cardiovascular Research, Charité - University School of Medicine, Berlin, Germany
| | - Andreas L Birkenfeld
- Section of Metabolic Vascular Medicine, Medical Clinic III and Paul Langerhans Institute Dresden (PLID), a member of the German Center for Diabetes Research (DZD), Technische Universität Dresden, Germany; Section of Diabetes and Nutritional Sciences, Rayne Institute, Denmark Hill Campus, King's College London, UK
| | - Utpal B Pajvani
- Department of Medicine, Columbia University, New York, NY 10032, USA.
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112
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Neuhaus-Follini A, Bashaw GJ. The Intracellular Domain of the Frazzled/DCC Receptor Is a Transcription Factor Required for Commissural Axon Guidance. Neuron 2015; 87:751-63. [PMID: 26291159 DOI: 10.1016/j.neuron.2015.08.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 07/24/2015] [Accepted: 08/03/2015] [Indexed: 10/23/2022]
Abstract
In commissural neurons of Drosophila, the conserved Frazzled (Fra)/Deleted in Colorectal Cancer (DCC) receptor promotes midline axon crossing by signaling locally in response to Netrin and by inducing transcription of commissureless (comm), an antagonist of Slit-Roundabout midline repulsion, through an unknown mechanism. Here, we show that Fra is cleaved to release its intracellular domain (ICD), which shuttles between the cytoplasm and the nucleus, where it functions as a transcriptional activator. Rescue and gain-of-function experiments demonstrate that the Fra ICD is sufficient to regulate comm expression and that both γ-secretase proteolysis of Fra and Fra's function as a transcriptional activator are required for its ability to regulate comm in vivo. Our data uncover an unexpected role for the Fra ICD as a transcription factor whose activity regulates the responsiveness of commissural axons at the midline and raise the possibility that nuclear signaling may be a common output of axon guidance receptors.
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Affiliation(s)
- Alexandra Neuhaus-Follini
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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113
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Walter J. Twenty Years of Presenilins--Important Proteins in Health and Disease. Mol Med 2015; 21 Suppl 1:S41-8. [PMID: 26605647 DOI: 10.2119/molmed.2015.00163] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 07/01/2015] [Indexed: 01/01/2023] Open
Abstract
Alzheimer's disease (AD) is characterized by progressive decline in cognitive functions associated with depositions of aggregated proteins in the form of extracellular plaques and neurofibrillary tangles in the brain. Extracellular plaques contain characteristic fibrils of amyloid β peptides (Aβ); tangles consist of paired helical filaments of the microtubuli-associated protein tau. Although AD manifests predominantly at ages above 65 years, rare cases show a much earlier onset of disease symptoms with very similar neuropathological characteristics. In 1995, two homologous genes were identified, in which mutations are associated with dominantly inherited familial forms of early onset AD. The genes therefore were dubbed presenilins (PS) and encode polytopic transmembrane proteins. At this time the role of these proteins in the pathogenesis of AD and their biological function in general were completely unknown. However, individuals carrying PS mutations showed alterations in the composition of different length variants of Aβ peptides in blood and cerebrospinal fluid, which indicated the potential involvement of presenilins in the metabolism of Aβ. After 20 years of intense research, the roles of presenilins in Aβ generation as well as important functions in biological processes have been identified. Presenilins represent the catalytic components of protease complexes that directly cleave the amyloid precursor protein (APP) but also many other proteins with important physiological functions. Here, the progress in presenilin research from basic characterization of their cellular functions to the targeting in clinical trials for AD therapy, and potential future directions, will be discussed.
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Affiliation(s)
- Jochen Walter
- Department of Neurology, University of Bonn, Bonn, Germany
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114
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Joshi G, Bekier ME, Wang Y. Golgi fragmentation in Alzheimer's disease. Front Neurosci 2015; 9:340. [PMID: 26441511 PMCID: PMC4585163 DOI: 10.3389/fnins.2015.00340] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 09/08/2015] [Indexed: 11/24/2022] Open
Abstract
The Golgi apparatus is an essential cellular organelle for post-translational modifications, sorting, and trafficking of membrane and secretory proteins. Proper functionality of the Golgi requires the formation of its unique cisternal-stacking morphology. The Golgi structure is disrupted in a variety of neurodegenerative diseases, suggesting a common mechanism and contribution of Golgi defects in neurodegenerative disorders. A recent study on Alzheimer's disease (AD) revealed that phosphorylation of the Golgi stacking protein GRASP65 disrupts its function in Golgi structure formation, resulting in Golgi fragmentation. Inhibiting GRASP65 phosphorylation restores the Golgi morphology from Aβ-induced fragmentation and reduces Aβ production. Perturbing Golgi structure and function in neurons may directly impact trafficking, processing, and sorting of a variety of proteins essential for synaptic and dendritic integrity. Therefore, Golgi defects may ultimately promote the development of AD. In the current review, we focus on the cellular impact of impaired Golgi morphology and its potential relationship to AD disease development.
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Affiliation(s)
- Gunjan Joshi
- Department of Molecular, Cellular and Developmental Biology, University of Michigan Ann Arbor, MI, USA
| | - Michael E Bekier
- Department of Molecular, Cellular and Developmental Biology, University of Michigan Ann Arbor, MI, USA
| | - Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan Ann Arbor, MI, USA ; Department of Neurology, University of Michigan School of Medicine Ann Arbor, MI, USA
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115
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Zhang S, Lei C, Liu P, Zhang M, Tao W, Liu H, Liu M. Association between variant amyloid deposits and motor deficits in FAD-associated presenilin-1 mutations: A systematic review. Neurosci Biobehav Rev 2015; 56:180-92. [DOI: 10.1016/j.neubiorev.2015.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 06/20/2015] [Accepted: 07/06/2015] [Indexed: 01/16/2023]
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116
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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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117
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Bhat AH, Dar KB, Anees S, Zargar MA, Masood A, Sofi MA, Ganie SA. Oxidative stress, mitochondrial dysfunction and neurodegenerative diseases; a mechanistic insight. Biomed Pharmacother 2015; 74:101-10. [PMID: 26349970 DOI: 10.1016/j.biopha.2015.07.025] [Citation(s) in RCA: 605] [Impact Index Per Article: 67.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 07/26/2015] [Indexed: 12/23/2022] Open
Abstract
Mitochondria is one of the main source of oxidative stress (ROS), as it utilizes the oxygen for the energy production. ROS and RNS are normally generated by tightly regulated enzymes. Excessive stimulation of NAD(P)H and electron transport chain leads to the overproduction of ROS, results in oxidative stress, which is a good mediator to injure the cell structures, lipids, proteins, and DNA. Various oxidative events implicated in many diseases due to oxidative stress include alteration in mitochondrial proteins, mitochondrial lipids and mitochondrial DNA, Which in turn leads to the damage to nerve cell as they are metabolically very active. ROS/RNS at moderate concentrations also play roles in normal physiology of many processes like signaling pathways, induction of mitogenic response and in defense against infectious pathogens. Oxidative stress has been considered to be the main cause in the etiology of many diseases, which includes Parkinson's and Alzheimer diseases. Several PD associated genes have been found to be involved in mitochondrial function, dynamics and morphology as well. This review includes source of free radical generation, chemistry and biochemistry of ROS/RNS and mitochondrial dysfunction and the mechanism involved in neurodegenerative diseases.
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Affiliation(s)
- Aashiq Hussain Bhat
- Department of Clinical Biochemistry, University of Kashmir, Srinagar 190006, India
| | - Khalid Bashir Dar
- Department of Clinical Biochemistry, University of Kashmir, Srinagar 190006, India
| | - Suhail Anees
- Department of Clinical Biochemistry, University of Kashmir, Srinagar 190006, India
| | | | - Akbar Masood
- Department of Biochemistry, University of Kashmir, Srinagar 190006, India
| | - Manzoor Ahmad Sofi
- Department of Clinical Biochemistry, University of Kashmir, Srinagar 190006, India
| | - Showkat Ahmad Ganie
- Department of Clinical Biochemistry, University of Kashmir, Srinagar 190006, India.
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118
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Jo EH, Ahn JS, Mo JS, Yoon JH, Ann EJ, Baek HJ, Lee HJ, Kim SH, Kim MY, Park HS. Akt1 phosphorylates Nicastrin to regulate its protein stability and activity. J Neurochem 2015; 134:799-810. [DOI: 10.1111/jnc.13173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 04/02/2015] [Accepted: 05/05/2015] [Indexed: 11/28/2022]
Affiliation(s)
- Eun-Hye Jo
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Ji-Seon Ahn
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Jung-Soon Mo
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Ji-Hye Yoon
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Eun-Jung Ann
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Hyeong-Jin Baek
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Hye-Jin Lee
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Seol-Hee Kim
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Mi-Yeon Kim
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
| | - Hee-Sae Park
- Hormone Research Center; School of Biological Sciences and Technology; Chonnam National University; Gwangju Korea
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119
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López AR, Dimitrov M, Gerber H, Braman V, Hacker DL, Wurm FM, Fraering PC. Production of active glycosylation-deficient γ-secretase complex for crystallization studies. Biotechnol Bioeng 2015; 112:2516-26. [PMID: 26059427 DOI: 10.1002/bit.25675] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/28/2015] [Accepted: 06/01/2015] [Indexed: 12/26/2022]
Abstract
Alzheimer's disease (AD)-associated γ-secretase is a ubiquitously expressed multi-subunit protease complex embedded in the lipid bilayer of cellular compartments including endosomes and the plasma membrane. Although γ-secretase is of crucial interest for AD drug discovery, its atomic structure remains unresolved. γ-Secretase assembly and maturation is a multistep process, which includes extensive glycosylation on nicastrin (NCT), the only γ-secretase subunit having a large extracellular domain. These posttranslational modifications lead to protein heterogeneity that likely prevents the three-dimensional (3D) crystallization of the protease complex. To overcome this issue, we have engineered a Chinese hamster ovary (CHO) cell line deficient in complex sugar modifications (CHO lec1) to overexpress the four subunits of γ-secretase as a functional complex. We purified glycosylation-deficient γ-secretase from this recombinant cell line (CL1-9) and fully glycosylated γ-secretase from a recombinant CHO DG44-derived cell line (SS20). We characterized both complexes biochemically and pharmacologically in vitro. Interestingly, we found that the complex oligosaccharides, which largely decorate the extracellular domain of fully glycosylated NCT, are not involved in the proper assembly and maturation of the complex, and are dispensable for the specific generation, in physiological ratios, of the amyloid precursor protein (APP) cleavage products. In conclusion, we propose a novel bioengineering approach for the production of functional glycosylation-deficient γ-secretase, which may be suitable for crystallization studies. We expect that these findings will contribute both to solving the high-resolution 3D structure of γ-secretase and to structure-based drug discovery for AD.
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Affiliation(s)
- Andrés Ricardo López
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Mitko Dimitrov
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Hermeto Gerber
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Virginie Braman
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - David L Hacker
- Laboratory for Cellular Biotechnology, Institute of Bioengineering and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Florian M Wurm
- Laboratory for Cellular Biotechnology, Institute of Bioengineering and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland
| | - Patrick C Fraering
- Laboratory of Molecular and Cellular Biology of Alzheimer's Disease, Brain Mind Institute and School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland.
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120
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Sun W, Pei L. microRNA Expression Profiling of Propofol-Treated Developing Rat Hippocampal Astrocytes. DNA Cell Biol 2015; 34:511-23. [PMID: 26083276 DOI: 10.1089/dna.2015.2831] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Although propofol exerts toxic effects on the developing central nervous system (CNS), it remains a first-choice anesthetic in the pediatric population. Astrocytes represent a major glial cell population whose role in CNS development is widely appreciated and that has been recently shown to be mediated in large part by microRNAs (miRNAs). In contrast, relatively little is known about the roles of miRNAs in developing astrocytes during propofol treatment. Here, miRNA microarray was used to profile fluctuations in miRNA expression in immature hippocampal astrocytes in response to propofol treatment, and results were subsequently validated using quantitative real-time polymerase chain reaction. Predictive analysis of genes targeted by propofol-regulated miRNAs indicated enrichment of genes in the gene ontology (GO) nervous system development and differentiation category, and in the Kyoto encyclopedia of genes and genomes (KEGG) apoptotic pathway category. A total of 24 (10 short-term dosage and 14 long-term dosage) miRNAs were significantly regulated, one of which was rno-miR-665. Ectopic overexpression and silencing of rno-miR-665 demonstrated its role in the neurotoxic effects of propofol on hippocampal immature astrocytes. We present evidence that the role of rno-miR-665 in anesthesia-induced disturbances in astroglia development may involve direct downregulation of the anti-apoptotic gene Bcl2l1, and subsequent increased caspase-3-mediated apoptosis. Our results shed light on the anesthetic mechanism of propofol and have implications for its use in the clinical setting.
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Affiliation(s)
- Wenchong Sun
- Department of Anesthesiology, The First Affiliated Hospital, China Medical University , Shenyang, China
| | - Ling Pei
- Department of Anesthesiology, The First Affiliated Hospital, China Medical University , Shenyang, China
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121
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Lim A, Moussavi Nik SH, Ebrahimie E, Lardelli M. Analysis of nicastrin gene phylogeny and expression in zebrafish. Dev Genes Evol 2015; 225:171-8. [DOI: 10.1007/s00427-015-0500-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 04/24/2015] [Indexed: 11/24/2022]
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122
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Bohm C, Chen F, Sevalle J, Qamar S, Dodd R, Li Y, Schmitt-Ulms G, Fraser PE, St George-Hyslop PH. Current and future implications of basic and translational research on amyloid-β peptide production and removal pathways. Mol Cell Neurosci 2015; 66:3-11. [PMID: 25748120 PMCID: PMC4503820 DOI: 10.1016/j.mcn.2015.02.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 02/26/2015] [Accepted: 02/27/2015] [Indexed: 01/12/2023] Open
Abstract
Inherited variants in multiple different genes are associated with increased risk for Alzheimer's disease (AD). In many of these genes, the inherited variants alter some aspect of the production or clearance of the neurotoxic amyloid β-peptide (Aβ). Thus missense, splice site or duplication mutants in the presenilin 1 (PS1), presenilin 2 (PS2) or the amyloid precursor protein (APP) genes, which alter the levels or shift the balance of Aβ produced, are associated with rare, highly penetrant autosomal dominant forms of Familial Alzheimer's Disease (FAD). Similarly, the more prevalent late-onset forms of AD are associated with both coding and non-coding variants in genes such as SORL1, PICALM and ABCA7 that affect the production and clearance of Aβ. This review summarises some of the recent molecular and structural work on the role of these genes and the proteins coded by them in the biology of Aβ. We also briefly outline how the emerging knowledge about the pathways involved in Aβ generation and clearance can be potentially targeted therapeutically. This article is part of Special Issue entitled "Neuronal Protein".
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Affiliation(s)
- C Bohm
- Tanz Centre for Research in Neurodegenerative Diseases, Departments of Medicine, Laboratory Medicine and Pathobiology and Medical Biophysics, University of Toronto, Krembil Discovery Tower, 6th Floor-6KD417, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada
| | - F Chen
- Tanz Centre for Research in Neurodegenerative Diseases, Departments of Medicine, Laboratory Medicine and Pathobiology and Medical Biophysics, University of Toronto, Krembil Discovery Tower, 6th Floor-6KD417, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada
| | - J Sevalle
- Tanz Centre for Research in Neurodegenerative Diseases, Departments of Medicine, Laboratory Medicine and Pathobiology and Medical Biophysics, University of Toronto, Krembil Discovery Tower, 6th Floor-6KD417, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada
| | - S Qamar
- Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrookes Hospital, Hills Road, Cambridge CB2 0XY, UK
| | - R Dodd
- Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrookes Hospital, Hills Road, Cambridge CB2 0XY, UK
| | - Y Li
- Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrookes Hospital, Hills Road, Cambridge CB2 0XY, UK
| | - G Schmitt-Ulms
- Tanz Centre for Research in Neurodegenerative Diseases, Departments of Medicine, Laboratory Medicine and Pathobiology and Medical Biophysics, University of Toronto, Krembil Discovery Tower, 6th Floor-6KD417, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada
| | - P E Fraser
- Tanz Centre for Research in Neurodegenerative Diseases, Departments of Medicine, Laboratory Medicine and Pathobiology and Medical Biophysics, University of Toronto, Krembil Discovery Tower, 6th Floor-6KD417, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada
| | - P H St George-Hyslop
- Tanz Centre for Research in Neurodegenerative Diseases, Departments of Medicine, Laboratory Medicine and Pathobiology and Medical Biophysics, University of Toronto, Krembil Discovery Tower, 6th Floor-6KD417, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada; Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrookes Hospital, Hills Road, Cambridge CB2 0XY, UK.
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123
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Cleavage of amyloid precursor protein by an archaeal presenilin homologue PSH. Proc Natl Acad Sci U S A 2015; 112:3344-9. [PMID: 25733893 DOI: 10.1073/pnas.1502150112] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Aberrant cleavage of amyloid precursor protein (APP) by γ-secretase contributes to the development of Alzheimer's disease. More than 200 disease-derived mutations have been identified in presenilin (the catalytic subunit of γ-secretase), making modulation of γ-secretase activity a potentially attractive therapeutic opportunity. Unfortunately, the technical challenges in dealing with intact γ-secretase have hindered discovery of modulators and demand a convenient substitute approach. Here we report that, similar to γ-secretase, the archaeal presenilin homolog PSH faithfully processes the substrate APP C99 into Aβ42, Aβ40, and Aβ38. The molar ratio of the cleavage products Aβ42 over Aβ40 by PSH is nearly identical to that by γ-secretase. The proteolytic activity of PSH is specifically suppressed by presenilin-specific inhibitors. Known modulators of γ-secretase also modulate PSH similarly in terms of the Aβ42/Aβ40 ratio. Structural analysis reveals association of a known γ-secretase inhibitor with PSH between its two catalytic aspartate residues. These findings identify PSH as a surrogate protease for the screening of agents that may regulate the protease activity and the cleavage preference of γ-secretase.
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124
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Vardarajan BN, Zhang Y, Lee JH, Cheng R, Bohm C, Ghani M, Reitz C, Reyes-Dumeyer D, Shen Y, Rogaeva E, St George-Hyslop P, Mayeux R. Coding mutations in SORL1 and Alzheimer disease. Ann Neurol 2015; 77:215-27. [PMID: 25382023 PMCID: PMC4367199 DOI: 10.1002/ana.24305] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 10/10/2014] [Accepted: 10/17/2014] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Common single nucleotide polymorphisms in the SORL1 gene have been associated with late onset Alzheimer disease (LOAD), but causal variants have not been fully characterized nor has the mechanism been established. The study was undertaken to identify functional SORL1 mutations in patients with LOAD. METHODS This was a family- and cohort-based genetic association study. Caribbean Hispanics with familial and sporadic LOAD and similarly aged controls were recruited from the United States and the Dominican Republic, and patients with sporadic disease of Northern European origin were recruited from Canada. Prioritized coding variants in SORL1 were detected by targeted resequencing and validated by genotyping in additional family members and unrelated healthy controls. Variants transfected into human embryonic kidney 293 cell lines were tested for Aβ40 and Aβ42 secretion, and the amount of the amyloid precursor protein (APP) secreted at the cell surface was determined. RESULTS Seventeen coding exonic variants were significantly associated with disease. Two rare variants (rs117260922-E270K and rs143571823-T947M) with minor allele frequency (MAF) < 1% and 1 common variant (rs2298813-A528T) with MAF = 14.9% segregated within families and were deemed deleterious to the coding protein. Transfected cell lines showed increased Aβ40 and Aβ42 secretion for the rare variants (E270K and T947M) and increased Aβ42 secretion for the common variant (A528T). All mutants increased the amount of APP at the cell surface, although in slightly different ways, thereby failing to direct full-length APP into the retromer-recycling endosome pathway. INTERPRETATION Common and rare variants in SORL1 elevate the risk of LOAD by directly affecting APP processing, which in turn can result in increased Aβ40 and Aβ42 secretion.
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Affiliation(s)
- Badri N. Vardarajan
- The Taub Institute for Research on Alzheimer’s Disease and the Aging Brain
- The Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Yalun Zhang
- Tanz Centre for Research in Neurodegenerative Diseases, and Department of Medicine, University of Toronto, Krembil Discovery Tower, 60 Leonard Avenue, Toronto, Ontario, Canada, M5T 2S8
| | - Joseph H. Lee
- The Taub Institute for Research on Alzheimer’s Disease and the Aging Brain
- The Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Cambridge Institute for Medical Research, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK, CB2 0XY
| | - Rong Cheng
- The Taub Institute for Research on Alzheimer’s Disease and the Aging Brain
- The Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Christopher Bohm
- Tanz Centre for Research in Neurodegenerative Diseases, and Department of Medicine, University of Toronto, Krembil Discovery Tower, 60 Leonard Avenue, Toronto, Ontario, Canada, M5T 2S8
| | - Mahdi Ghani
- Tanz Centre for Research in Neurodegenerative Diseases, and Department of Medicine, University of Toronto, Krembil Discovery Tower, 60 Leonard Avenue, Toronto, Ontario, Canada, M5T 2S8
| | - Christiane Reitz
- The Taub Institute for Research on Alzheimer’s Disease and the Aging Brain
- The Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA
- The Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Dolly Reyes-Dumeyer
- The Taub Institute for Research on Alzheimer’s Disease and the Aging Brain
- The Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Yufeng Shen
- The Department Systems Biology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Ekaterina Rogaeva
- Tanz Centre for Research in Neurodegenerative Diseases, and Department of Medicine, University of Toronto, Krembil Discovery Tower, 60 Leonard Avenue, Toronto, Ontario, Canada, M5T 2S8
| | - Peter St George-Hyslop
- Tanz Centre for Research in Neurodegenerative Diseases, and Department of Medicine, University of Toronto, Krembil Discovery Tower, 60 Leonard Avenue, Toronto, Ontario, Canada, M5T 2S8
- Cambridge Institute for Medical Research, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK, CB2 0XY
| | - Richard Mayeux
- The Taub Institute for Research on Alzheimer’s Disease and the Aging Brain
- The Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA
- The Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
- The Department Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA
- The Department of Epidemiology, School of Public Health, Columbia University, New York, NY, USA
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125
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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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126
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Li Y, Bohm C, Dodd R, Chen F, Qamar S, Schmitt-Ulms G, Fraser PE, St George-Hyslop PH. Structural biology of presenilin 1 complexes. Mol Neurodegener 2014; 9:59. [PMID: 25523933 PMCID: PMC4326451 DOI: 10.1186/1750-1326-9-59] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 12/12/2014] [Indexed: 11/17/2022] Open
Abstract
The presenilin genes were first identified as the site of missense mutations causing early onset autosomal dominant familial Alzheimer's disease. Subsequent work has shown that the presenilin proteins are the catalytic subunits of a hetero-tetrameric complex containing APH1, nicastrin and PEN-2. This complex (variously termed presenilin complex or gamma-secretase complex) performs an unusual type of proteolysis in which the transmembrane domains of Type I proteins are cleaved within the hydrophobic compartment of the membrane. This review describes some of the molecular and structural biology of this unusual enzyme complex. The presenilin complex is a bilobed structure. The head domain contains the ectodomain of nicastrin. The base domain contains a central cavity with a lateral cleft that likely provides the route for access of the substrate to the catalytic cavity within the centre of the base domain. There are reciprocal allosteric interactions between various sites in the complex that affect its function. For instance, binding of Compound E, a peptidomimetic inhibitor to the PS1 N-terminus, induces significant conformational changes that reduces substrate binding at the initial substrate docking site, and thus inhibits substrate cleavage. However, there is a reciprocal allosteric interaction between these sites such that prior binding of the substrate to the initial docking site paradoxically increases the binding of the Compound E peptidomimetic inhibitor. Such reciprocal interactions are likely to form the basis of a gating mechanism that underlies access of substrate to the catalytic site. An increasingly detailed understanding of the structural biology of the presenilin complex is an essential step towards rational design of substrate- and/or cleavage site-specific modulators of presenilin complex function.
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Affiliation(s)
| | | | | | | | | | | | | | - Peter H St George-Hyslop
- Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrookes Hospital, Hills Road, Cambridge CB2 0XY, UK.
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127
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Zhang X, Li Y, Xu H, Zhang YW. The γ-secretase complex: from structure to function. Front Cell Neurosci 2014; 8:427. [PMID: 25565961 PMCID: PMC4263104 DOI: 10.3389/fncel.2014.00427] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 11/27/2014] [Indexed: 12/21/2022] Open
Abstract
One of the most critical pathological features of Alzheimer’s disease (AD) is the accumulation of β-amyloid (Aβ) peptides that form extracellular senile plaques in the brain. Aβ is derived from β-amyloid precursor protein (APP) through sequential cleavage by β- and γ-secretases. γ-secretase is a high molecular weight complex minimally composed of four components: presenilins (PS), nicastrin, anterior pharynx defective 1 (APH-1), and presenilin enhancer 2 (PEN-2). In addition to APP, γ-secretase also cleaves many other type I transmembrane (TM) protein substrates. As a crucial enzyme for Aβ production, γ-secretase is an appealing therapeutic target for AD. Here, we summarize current knowledge on the structure and function of γ-secretase, as well as recent progress in developing γ-secretase targeting drugs for AD treatment.
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Affiliation(s)
- Xian Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University Xiamen, FJ, China
| | - Yanfang Li
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University Xiamen, FJ, China
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University Xiamen, FJ, China ; Degenerative Disease Research Program, Sanford-Burnham Medical Research Institute La Jolla, CA, USA
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University Xiamen, FJ, China
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128
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Strömberg K, Eketjäll S, Georgievska B, Tunblad K, Eliason K, Olsson F, Radesäter AC, Klintenberg R, Arvidsson PI, von Berg S, Fälting J, Cowburn RF, Dabrowski M. Combining an amyloid-beta (Aβ) cleaving enzyme inhibitor with a γ-secretase modulator results in an additive reduction of Aβ production. FEBS J 2014; 282:65-73. [DOI: 10.1111/febs.13103] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/31/2014] [Accepted: 10/06/2014] [Indexed: 12/27/2022]
Affiliation(s)
- Kia Strömberg
- Department of Neuroscience; AstraZeneca R&D; CNS/Pain iMED; Södertälje Sweden
| | - Susanna Eketjäll
- AstraZeneca Translational Science Centre; Science for Life Laboratory; Solna Sweden
| | - Biljana Georgievska
- Department of Neuroscience; AstraZeneca R&D; CNS/Pain iMED; Södertälje Sweden
| | - Karin Tunblad
- Department of Neuroscience; AstraZeneca R&D; CNS/Pain iMED; Södertälje Sweden
| | - Kristina Eliason
- Department of Neuroscience; AstraZeneca R&D; CNS/Pain iMED; Södertälje Sweden
| | - Fredrik Olsson
- Department of Neuroscience; AstraZeneca R&D; CNS/Pain iMED; Södertälje Sweden
| | | | - Rebecka Klintenberg
- Department of Neuroscience; AstraZeneca R&D; CNS/Pain iMED; Södertälje Sweden
| | - Per I. Arvidsson
- Project Management, AstraZeneca R&D; CNS/Pain iMED; Södertälje Sweden
| | - Stefan von Berg
- Department of Medicinal Chemistry; R&I iMed; AstraZeneca R&D Mölndal; Sweden
| | - Johanna Fälting
- Project Management, AstraZeneca R&D; CNS/Pain iMED; Södertälje Sweden
| | - Richard F. Cowburn
- Department of Neuroscience; AstraZeneca R&D; CNS/Pain iMED; Södertälje Sweden
| | - Michael Dabrowski
- Department of Neuroscience; AstraZeneca R&D; CNS/Pain iMED; Södertälje Sweden
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129
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Wang X, Huang T, Zhao Y, Zheng Q, Thompson RC, Bu G, Zhang YW, Hong W, Xu H. Sorting nexin 27 regulates Aβ production through modulating γ-secretase activity. Cell Rep 2014; 9:1023-33. [PMID: 25437557 DOI: 10.1016/j.celrep.2014.09.037] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 08/04/2014] [Accepted: 09/18/2014] [Indexed: 12/14/2022] Open
Abstract
Patients with Down syndrome (DS) invariably develop Alzheimer's disease (AD) pathology in their 40s. We have recently found that overexpression of a chromosome 21-encoded microRNA-155 results in decreased levels of the membrane trafficking component, SNX27, diminishing glutamate receptor recycling and thereby impairing synaptic functions in DS. Here, we report a function of SNX27 in regulating β-amyloid (Aβ) generation by modulating γ-secretase activity. Downregulation of SNX27 using RNAi increased Aβ production, whereas overexpression of full-length SNX27, but not SNX27ΔPDZ, reversed the RNAi-mediated Aβ elevation. Moreover, genetic deletion of Snx27 promoted Aβ production and neuronal loss, whereas overexpression of SNX27 using an adeno-associated viral (AAV) vector reduced hippocampal Aβ levels in a transgenic AD mouse model. SNX27 associates with the γ-secretase complex subunit presenilin 1; this interaction dissociates the γ-secretase complex, thus decreasing its proteolytic activity. Our study establishes a molecular mechanism for Aβ-dependent pathogenesis in both DS and AD.
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Affiliation(s)
- Xin Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen 361005, China; Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Timothy Huang
- Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Yingjun Zhao
- Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Qiuyang Zheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen 361005, China; Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Robert C Thompson
- Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Guojun Bu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen 361005, China
| | - Yun-wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen 361005, China; Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Wanjin Hong
- Institute for Biomedical Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen 361005, China; Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen 361005, China; Degenerative Disease Research Program, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA.
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130
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Liang H, Zhang Y, Shi X, Wei T, Lou J. Role of Notch-1 signaling pathway in PC12 cell apoptosis induced by amyloid beta-peptide (25-35). Neural Regen Res 2014; 9:1297-302. [PMID: 25221582 PMCID: PMC4160856 DOI: 10.4103/1673-5374.137577] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2014] [Indexed: 11/12/2022] Open
Abstract
Recent studies have demonstrated that Notch-1 expression is increased in the hippocampus of Alzheimer's disease patients. We speculate that Notch-1 signaling may be involved in PC12 cell apoptosis induced by amyloid beta-peptide (25–35) (Aβ25–35). In the present study, PC12 cells were cultured with different doses (0, 0.1, 1.0, 10 and 100 nmol/L) of N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester, a Notch-1 signaling pathway inhibitor, for 30 minutes. Then cultured cells were induced with Aβ25–35 for 48 hours. Pretreatment of PC12 cells with high doses of N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (> 10 nmol/L) prolonged the survival of PC12 cells after Aβ25–35 induction, decreased the expression of apoptosis-related proteins caspase-3, -8, -9, increased the activity of oxidative stress-related superoxide dismutase and catalase, inhibited the production of active oxygen, and reduced nuclear factor kappa B expression. This study indicates that the Notch-1 signaling pathway plays a pivotal role in Aβ25–35-induced PC12 apoptosis.
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Affiliation(s)
- Huimin Liang
- Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China ; Huaihe Hospital of Henan University, Kaifeng, Henan Province, China
| | - Yaozhou Zhang
- Department of Biotechnology, Xinyang Agricultural College, Xinyang, Henan Province, China
| | - Xiaoyan Shi
- Pharmaceutical College of Henan University, Zhengzhou, Henan Province, China
| | - Tianxiang Wei
- Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China
| | - Jiyu Lou
- Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China
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131
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Alexander AG, Marfil V, Li C. Use of Caenorhabditis elegans as a model to study Alzheimer's disease and other neurodegenerative diseases. Front Genet 2014; 5:279. [PMID: 25250042 PMCID: PMC4155875 DOI: 10.3389/fgene.2014.00279] [Citation(s) in RCA: 189] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 07/31/2014] [Indexed: 12/12/2022] Open
Abstract
Advances in research and technology has increased our quality of life, allowed us to combat diseases, and achieve increased longevity. Unfortunately, increased longevity is accompanied by a rise in the incidences of age-related diseases such as Alzheimer’s disease (AD). AD is the sixth leading cause of death, and one of the leading causes of dementia amongst the aged population in the USA. It is a progressive neurodegenerative disorder, characterized by the prevalence of extracellular Aβ plaques and intracellular neurofibrillary tangles, derived from the proteolysis of the amyloid precursor protein (APP) and the hyperphosphorylation of microtubule-associated protein tau, respectively. Despite years of extensive research, the molecular mechanisms that underlie the pathology of AD remain unclear. Model organisms, such as the nematode, Caenorhabditis elegans, present a complementary approach to addressing these questions. C. elegans has many advantages as a model system to study AD and other neurodegenerative diseases. Like their mammalian counterparts, they have complex biochemical pathways, most of which are conserved. Genes in which mutations are correlated with AD have counterparts in C. elegans, including an APP-related gene, apl-1, a tau homolog, ptl-1, and presenilin homologs, such as sel-12 and hop-1. Since the neuronal connectivity in C. elegans has already been established, C. elegans is also advantageous in modeling learning and memory impairments seen during AD. This article addresses the insights C. elegans provide in studying AD and other neurodegenerative diseases. Additionally, we explore the advantages and drawbacks associated with using this model.
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Affiliation(s)
- Adanna G Alexander
- Department of Biology, City College of New York New York, NY, USA ; Department of Biology, The Graduate Center, City University of New York New York, NY, USA
| | - Vanessa Marfil
- Department of Biology, City College of New York New York, NY, USA
| | - Chris Li
- Department of Biology, City College of New York New York, NY, USA ; Department of Biology, The Graduate Center, City University of New York New York, NY, USA
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132
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Abstract
γ-Secretase is an intramembrane protease responsible for the generation of amyloid-β (Aβ) peptides. Aberrant accumulation of Aβ leads to the formation of amyloid plaques in the brain of patients with Alzheimer's disease. Nicastrin is the putative substrate-recruiting component of the γ-secretase complex. No atomic-resolution structure had been identified on γ-secretase or any of its four components, hindering mechanistic understanding of γ-secretase function. Here we report the crystal structure of nicastrin from Dictyostelium purpureum at 1.95-Å resolution. The extracellular domain of nicastrin contains a large lobe and a small lobe. The large lobe of nicastrin, thought to be responsible for substrate recognition, associates with the small lobe through a hydrophobic pivot at the center. The putative substrate-binding pocket is shielded from the small lobe by a lid, which blocks substrate entry. These structural features suggest a working model of nicastrin function. Analysis of nicastrin structure provides insights into the assembly and architecture of the γ-secretase complex.
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133
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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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134
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Smolarkiewicz M, Skrzypczak T, Michalak M, Leśniewicz K, Walker JR, Ingram G, Wojtaszek P. Gamma-secretase subunits associate in intracellular membrane compartments in Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3015-27. [PMID: 24723404 PMCID: PMC4071823 DOI: 10.1093/jxb/eru147] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Gamma-secretase is a multisubunit complex with intramembrane proteolytic activity. In humans it was identified in genetic screens of patients suffering from familial forms of Alzheimer's disease, and since then it was shown to mediate cleavage of more than 80 substrates, including amyloid precursor protein or Notch receptor. Moreover, in animals, γ-secretase was shown to be involved in regulation of a wide range of cellular events, including cell signalling, regulation of endocytosis of membrane proteins, their trafficking, and degradation. Here we show that genes coding for γ-secretase homologues are present in plant genomes. Also, amino acid motifs crucial for γ-secretase activity are conserved in plants. Moreover, all γ-secretase subunits: PS1/PS2, APH-1, PEN-2, and NCT colocalize and interact with each other in Arabidopsis thaliana protoplasts. The intracellular localization of γ-secretase subunits in Arabidopsis protoplasts revealed a distribution in endomembrane system compartments that is consistent with data from animal studies. Together, our data may be considered as a starting point for analysis of γ-secretase in plants.
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Affiliation(s)
- Michalina Smolarkiewicz
- Department of Molecular and Cellular Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Tomasz Skrzypczak
- Department of Molecular and Cellular Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Michał Michalak
- Department of Molecular and Cellular Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Krzysztof Leśniewicz
- Department of Molecular and Cellular Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - J Ross Walker
- Institute of Molecular Plant Sciences, University of Edinburgh, King's Buildings, Mayfield Rd, Edinburgh EH9 3JH, UK
| | - Gwyneth Ingram
- Institute of Molecular Plant Sciences, University of Edinburgh, King's Buildings, Mayfield Rd, Edinburgh EH9 3JH, UK UMR 5667 CNRS-INRA-ENSL-UCB Lyon I, Reproduction et Développement des Plantes, ENS Lyon, 46, Allée d'Italie, 69364 LYON Cedex 07, France
| | - Przemysław Wojtaszek
- Department of Molecular and Cellular Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
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135
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Abstract
Synaptic dysfunction is widely thought to play a key role in the pathogenesis of Alzheimer's disease (AD). Presenilins, the major gene products involved in familial AD, are essential for short- and long-term synaptic plasticity in mature neurons as well as for the survival of cortical neurons during aging. Presenilin and nicastrin are both indispensable components of the γ-secretase complex, but it remains unknown whether presenilin regulates synaptic function in a γ-secretase-dependent or γ-secretase-independent manner and whether nicastrin plays similar roles in central synapses. In the current study, we address these questions using an electrophysiological approach to analyze nicastrin conditional knockout (cKO) mice in the hippocampal Schaffer collateral pathway. In these mice, we found that, even at 2 mo of age, deletion of nicastrin in excitatory neurons of the postnatal forebrain using Cre recombinase expressed under the control of the αCaMKII promoter led to deficits in presynaptic short-term plasticity including paired-pulse facilitation and frequency facilitation. Depletion of Ca(2+) in the endoplasmic reticulum mimics and occludes the presynaptic facilitation deficits in nicastrin cKO mice, suggesting that disrupted intracellular Ca(2+) homeostasis underlies the presynaptic deficits. In addition, NMDA receptor-mediated responses and long-term potentiation induced by theta-burst stimulation were decreased in nicastrin cKO mice at 3 mo but not at 2 mo of age. Together, these findings show that, similar to presenilins, nicastrin plays essential roles in the regulation of short- and long-term synaptic plasticity, highlighting the importance of γ-secretase in the function of mature synapses.
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136
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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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Wanngren J, Lara P, Ojemalm K, Maioli S, Moradi N, Chen L, Tjernberg LO, Lundkvist J, Nilsson I, Karlström H. Changed membrane integration and catalytic site conformation are two mechanisms behind the increased Aβ42/Aβ40 ratio by presenilin 1 familial Alzheimer-linked mutations. FEBS Open Bio 2014; 4:393-406. [PMID: 24918054 PMCID: PMC4050182 DOI: 10.1016/j.fob.2014.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 04/16/2014] [Accepted: 04/17/2014] [Indexed: 01/11/2023] Open
Abstract
Familial Alzheimer disease (FAD) mutations affect presenilin membrane integration. The transmembrane domains around the catalytic site are vulnerable to changes. All FAD mutations cause changes in the active site of the γ-secretase complex. The FAD mutants lead to a complex processing pattern of the amyloid precursor protein.
The enzyme complex γ-secretase generates amyloid β-peptide (Aβ), a 37–43-residue peptide associated with Alzheimer disease (AD). Mutations in presenilin 1 (PS1), the catalytical subunit of γ-secretase, result in familial AD (FAD). A unifying theme among FAD mutations is an alteration in the ratio Aβ species produced (the Aβ42/Aβ40 ratio), but the molecular mechanisms responsible remain elusive. In this report we have studied the impact of several different PS1 FAD mutations on the integration of selected PS1 transmembrane domains and on PS1 active site conformation, and whether any effects translate to a particular amyloid precursor protein (APP) processing phenotype. Most mutations studied caused an increase in the Aβ42/Aβ40 ratio, but via different mechanisms. The mutations that caused a particular large increase in the Aβ42/Aβ40 ratio did also display an impaired APP intracellular domain (AICD) formation and a lower total Aβ production. Interestingly, seven mutations close to the catalytic site caused a severely impaired integration of proximal transmembrane/hydrophobic sequences into the membrane. This structural defect did not correlate to a particular APP processing phenotype. Six selected FAD mutations, all of which exhibited different APP processing profiles and impact on PS1 transmembrane domain integration, were found to display an altered active site conformation. Combined, our data suggest that FAD mutations affect the PS1 structure and active site differently, resulting in several complex APP processing phenotypes, where the most aggressive mutations in terms of increased Aβ42/Aβ40 ratio are associated with a decrease in total γ-secretase activity.
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Key Words
- AD, Alzheimer disease
- AICD, amyloid precursor protein intracellular domain
- APP, amyloid precursor protein
- Alzheimer disease
- Amyloid β-peptide
- Aβ, amyloid-β peptide
- BD8, blastocyst-derived embryonic stem cells
- Bis-Tris, 2-(bis(2-hydroxyethyl)amino)-2-(hydroxymethyl)propane-1,3-diol
- CHAPSO, 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonic acid
- CRM, column-washed dog pancreas rough microsomes
- CTF, C-terminal fragment
- ER, endoplasmic reticulum
- Endo H, endoglycosidase H
- FAD, familial AD
- FLIM/FRET, Fluorescence Lifetime Imaging/ Fluorescence Resonance Energy Transfer
- GCB, γ-secretase inhibitor coupled to biotin
- GVP, Gal4VP16
- Lep, leader peptidase
- MGD, minimal glycosylation distance
- MSD, Meso Scale Discovery
- Membrane integration
- NTF, N-terminal fragment
- PS, presenilin
- Protein structure
- RM, rough microsomes
- TMD, transmembrane domains
- WT, wild type
- γ-Secretase
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Affiliation(s)
- Johanna Wanngren
- Department of NVS, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden
| | - Patricia Lara
- Department of Biochemistry & Biophysics, Stockholm University, Stockholm, Sweden
| | - Karin Ojemalm
- Department of Biochemistry & Biophysics, Stockholm University, Stockholm, Sweden
| | - Silvia Maioli
- Department of NVS, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden
| | - Nasim Moradi
- Department of Biochemistry & Biophysics, Stockholm University, Stockholm, Sweden
| | - Lu Chen
- Department of Biochemistry & Biophysics, Stockholm University, Stockholm, Sweden
| | - Lars O Tjernberg
- Department of NVS, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden
| | | | - IngMarie Nilsson
- Department of Biochemistry & Biophysics, Stockholm University, Stockholm, Sweden
| | - Helena Karlström
- Department of NVS, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden
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138
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Dawkins E, Small DH. Insights into the physiological function of the β-amyloid precursor protein: beyond Alzheimer's disease. J Neurochem 2014; 129:756-69. [PMID: 24517464 PMCID: PMC4314671 DOI: 10.1111/jnc.12675] [Citation(s) in RCA: 162] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 02/02/2014] [Accepted: 02/03/2014] [Indexed: 12/21/2022]
Abstract
The β-amyloid precursor protein (APP) has been extensively studied for its role as the precursor of the β-amyloid protein (Aβ) of Alzheimer's disease. However, the normal function of APP remains largely unknown. This article reviews studies on the structure, expression and post-translational processing of APP, as well as studies on the effects of APP in vitro and in vivo. We conclude that the published data provide strong evidence that APP has a trophic function. APP is likely to be involved in neural stem cell development, neuronal survival, neurite outgrowth and neurorepair. However, the mechanisms by which APP exerts its actions remain to be elucidated. The available evidence suggests that APP interacts both intracellularly and extracellularly to regulate various signal transduction mechanisms. This article reviews studies on the structure, expression and post-translational processing of β-amyloid precursor protein (APP), as well as studies on the effects of APP in vitro and in vivo. We conclude that the published data provide strong evidence that APP has a trophic function. APP is likely to be involved in neural stem cell development, neuronal survival, neurite outgrowth and neurorepair. However, the mechanisms by which APP exerts its actions remain to be elucidated. The available evidence suggests that APP interacts both intracellularly and extracellularly to regulate various signal transduction mechanisms.
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Affiliation(s)
- Edgar Dawkins
- Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia
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139
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Early onset Alzheimer's disease and oxidative stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2014; 2014:375968. [PMID: 24669286 PMCID: PMC3942075 DOI: 10.1155/2014/375968] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 11/18/2013] [Indexed: 01/30/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia in elderly adults. It is estimated that 10% of the world's population aged more than 60-65 years could currently be affected by AD, and that in the next 20 years, there could be more than 30 million people affected by this pathology. One of the great challenges in this regard is that AD is not just a scientific problem; it is associated with major psychosocial and ethical dilemmas and has a negative impact on national economies. The neurodegenerative process that occurs in AD involves a specific nervous cell dysfunction, which leads to neuronal death. Mutations in APP, PS1, and PS2 genes are causes for early onset AD. Several animal models have demonstrated that alterations in these proteins are able to induce oxidative damage, which in turn favors the development of AD. This paper provides a review of many, although not all, of the mutations present in patients with familial Alzheimer's disease and the association between some of these mutations with both oxidative damage and the development of the pathology.
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140
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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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141
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142
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Ruan L, Lau BWM, Wang J, Huang L, Zhuge Q, Wang B, Jin K, So KF. Neurogenesis in neurological and psychiatric diseases and brain injury: from bench to bedside. Prog Neurobiol 2013; 115:116-37. [PMID: 24384539 DOI: 10.1016/j.pneurobio.2013.12.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 12/08/2013] [Accepted: 12/12/2013] [Indexed: 02/08/2023]
Abstract
Researchers who have uncovered the presence of stem cells in an adult's central nervous system have not only challenged the dogma that new neurons cannot be generated during adulthood, but also shed light on the etiology and disease mechanisms underlying many neurological and psychiatric disorders. Brain trauma, neurodegenerative diseases, and psychiatric disorders pose enormous burdens at both personal and societal levels. Although medications for these disorders are widely used, the treatment mechanisms underlying the illnesses remain largely elusive. In the past decade, an increasing amount of evidence indicate that adult neurogenesis (i.e. generating new CNS neurons during adulthood) may be involved in the pathology of different CNS disorders, and thus neurogenesis may be a potential target area for treatments. Although new neurons were shown to be a major player in mediating treatment efficacy of neurological and psychotropic drugs on cognitive functions, it is still debatable if the altered production of new neurons can cause the disorders. This review hence seeks to discuss pre and current clinical studies that demonstrate the functional impact adult neurogenesis have on neurological and psychiatric illnesses while examining the related underlying disease mechanisms.
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Affiliation(s)
- Linhui Ruan
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA.
| | - Benson Wui-Man Lau
- Department of Rehabilitation Science, The Hong Kong Polytechnic University, Hong Kong, PR China
| | - Jixian Wang
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA
| | - Lijie Huang
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA
| | - Qichuan Zhuge
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China
| | - Brian Wang
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA
| | - Kunlin Jin
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA.
| | - Kwok-Fai So
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China; The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China; Research Centre of Heart, Brain, Hormone and Healthy Aging, Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China; GMH Institute of CNS Regeneration, Jinan University, Guangzhou, PR China.
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143
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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: 33] [Impact Index Per Article: 3.0] [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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144
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Sesele K, Thanopoulou K, Paouri E, Tsefou E, Klinakis A, Georgopoulos S. Conditional inactivation of nicastrin restricts amyloid deposition in an Alzheimer's disease mouse model. Aging Cell 2013; 12:1032-40. [PMID: 23826707 DOI: 10.1111/acel.12131] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2013] [Indexed: 12/15/2022] Open
Abstract
Production of Aβ by γ-secretase is a key event in Alzheimer's disease (AD). The γ-secretase complex consists of presenilin (PS) 1 or 2, nicastrin (ncstn), Pen-2, and Aph-1 and cleaves type I transmembrane proteins, including the amyloid precursor protein (APP). Although ncstn is widely accepted as an essential component of the complex required for γ-secretase activity, recent in vitro studies have suggested that ncstn is dispensable for APP processing and Aβ production. The focus of this study was to answer this controversy and evaluate the role of ncstn in Aβ generation and the development of the amyloid-related phenotype in the mouse brain. To eliminate ncstn expression in the mouse brain, we used a ncstn conditional knockout mouse that we mated with an established AD transgenic mouse model (5XFAD) and a neuronal Cre-expressing transgenic mouse (CamKIIα-iCre), to generate AD mice (5XFAD/CamKIIα-iCre/ncstn(f/f) mice) where ncstn was conditionally inactivated in the brain. 5XFAD/CamKIIα-iCre/ncstn(f/f) mice at 10 week of age developed a neurodegenerative phenotype with a significant reduction in Aβ production and formation of Aβ aggregates and the absence of amyloid plaques. Inactivation of nctsn resulted in substantial accumulation of APP-CTFs and altered PS1 expression. These results reveal a key role for ncstn in modulating Aβ production and amyloid plaque formation in vivo and suggest ncstn as a target in AD therapeutics.
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Affiliation(s)
- Katia Sesele
- Department of Cell Biology; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
| | - Kalliopi Thanopoulou
- Department of Cell Biology; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
| | - Evi Paouri
- Department of Cell Biology; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
| | - Eliona Tsefou
- Department of Cell Biology; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
| | - Apostolos Klinakis
- Department of Genetics and Gene Therapy; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
| | - Spiros Georgopoulos
- Department of Cell Biology; Biomedical Research Foundation; Academy of Athens; Athens 115 27 Greece
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145
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General anesthetics and β-amyloid protein. Prog Neuropsychopharmacol Biol Psychiatry 2013; 47:140-6. [PMID: 22918033 PMCID: PMC3510311 DOI: 10.1016/j.pnpbp.2012.08.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 08/02/2012] [Accepted: 08/02/2012] [Indexed: 11/23/2022]
Abstract
With roughly 234 million people undergoing surgery with anesthesia each year worldwide, it is important to determine whether commonly used anesthetics can induce any neurotoxicity. Alzheimer's disease (AD) is the most common form of age-related dementia, and a rapidly growing health problem. Several studies suggest that anesthesia could be associated with the development of AD. Moreover, studies in cultured cells and animals show that commonly used inhalation anesthetics may induce changes consistent with AD neuropathogenesis, e.g., β-amyloid protein accumulation. Therefore, in this mini review, we focus on the recent research investigating the effects of commonly used anesthetics including isoflurane, sevoflurane, desflurane, nitrous oxide, and propofol, on Aβ accumulation in vitro and in vivo. We further discuss the future direction of the research determining the effects of anesthetics on β-amyloid protein accumulation.
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146
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Schedin-Weiss S, Winblad B, Tjernberg LO. The role of protein glycosylation in Alzheimer disease. FEBS J 2013; 281:46-62. [PMID: 24279329 DOI: 10.1111/febs.12590] [Citation(s) in RCA: 225] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 10/25/2013] [Accepted: 10/28/2013] [Indexed: 12/18/2022]
Abstract
Glycosylation is one of the most common, and the most complex, forms of post-translational modification of proteins. This review serves to highlight the role of protein glycosylation in Alzheimer disease (AD), a topic that has not been thoroughly investigated, although glycosylation defects have been observed in AD patients. The major pathological hallmarks in AD are neurofibrillary tangles and amyloid plaques. Neurofibrillary tangles are composed of phosphorylated tau, and the plaques are composed of amyloid β-peptide (Aβ), which is generated from amyloid precursor protein (APP). Defects in glycosylation of APP, tau and other proteins have been reported in AD. Another interesting observation is that the two proteases required for the generation of amyloid β-peptide (Aβ), i.e. γ-secretase and β-secretase, also have roles in protein glycosylation. For instance, γ-secretase and β-secretase affect the extent of complex N-glycosylation and sialylation of APP, respectively. These processes may be important in AD pathogenesis, as proper intracellular sorting, processing and export of APP are affected by how it is glycosylated. Furthermore, lack of one of the key components of γ-secretase, presenilin, leads to defective glycosylation of many additional proteins that are related to AD pathogenesis and/or neuronal function, including nicastrin, reelin, butyrylcholinesterase, cholinesterase, neural cell adhesion molecule, v-ATPase, and tyrosine-related kinase B. Improved understanding of the effects of AD on protein glycosylation, and vice versa, may therefore be important for improving the diagnosis and treatment of AD patients.
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Affiliation(s)
- Sophia Schedin-Weiss
- Karolinska Institutet Alzheimer Disease Research Center (KI-ADRC), Novum, Stockholm, Sweden
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147
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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: 70] [Impact Index Per Article: 6.4] [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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148
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Li Y, Lu SHJ, Tsai CJ, Bohm C, Qamar S, Dodd RB, Meadows W, Jeon A, McLeod A, Chen F, Arimon M, Berezovska O, Hyman BT, Tomita T, Iwatsubo T, Johnson CM, Farrer LA, Schmitt-Ulms G, Fraser PE, St George-Hyslop PH. Structural interactions between inhibitor and substrate docking sites give insight into mechanisms of human PS1 complexes. Structure 2013; 22:125-35. [PMID: 24210759 PMCID: PMC3887256 DOI: 10.1016/j.str.2013.09.018] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 08/28/2013] [Accepted: 09/21/2013] [Indexed: 11/18/2022]
Abstract
Presenilin-mediated endoproteolysis of transmembrane proteins plays a key role in physiological signaling and in the pathogenesis of Alzheimer disease and some cancers. Numerous inhibitors have been found via library screens, but their structural mechanisms remain unknown. We used several biophysical techniques to investigate the structure of human presenilin complexes and the effects of peptidomimetic γ-secretase inhibitors. The complexes are bilobed. The head contains nicastrin ectodomain. The membrane-embedded base has a central channel and a lateral cleft, which may represent the initial substrate docking site. Inhibitor binding induces widespread structural changes, including rotation of the head and closure of the lateral cleft. These changes block substrate access to the catalytic pocket and inhibit the enzyme. Intriguingly, peptide substrate docking has reciprocal effects on the inhibitor binding site. Similar reciprocal shifts may underlie the mechanisms of other inhibitors and of the “lateral gate” through which substrates access to the catalytic site. The head contains nicastrin ectodomain and overhangs a solute-accessible cavity in base The base has a central channel and a lateral cleft (putative substrate docking site) Inhibitors close the cleft and channel and rotate the head, blocking substrate access
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Affiliation(s)
- Yi Li
- Department of Clinical Neurosciences, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Stephen Hsueh-Jeng Lu
- Department of Clinical Neurosciences, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Ching-Ju Tsai
- Department of Clinical Neurosciences, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Christopher Bohm
- Tanz Centre for Research in Neurodegenerative Diseases, and Departments of Medicine, Laboratory Medicine and Pathobiology, and Medical Biophysics, University of Toronto, Toronto, ON M5S 3H2, Canada
| | - Seema Qamar
- Department of Clinical Neurosciences, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Roger B Dodd
- Department of Clinical Neurosciences, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - William Meadows
- Department of Clinical Neurosciences, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Amy Jeon
- Tanz Centre for Research in Neurodegenerative Diseases, and Departments of Medicine, Laboratory Medicine and Pathobiology, and Medical Biophysics, University of Toronto, Toronto, ON M5S 3H2, Canada
| | - Adam McLeod
- Tanz Centre for Research in Neurodegenerative Diseases, and Departments of Medicine, Laboratory Medicine and Pathobiology, and Medical Biophysics, University of Toronto, Toronto, ON M5S 3H2, Canada
| | - Fusheng Chen
- Tanz Centre for Research in Neurodegenerative Diseases, and Departments of Medicine, Laboratory Medicine and Pathobiology, and Medical Biophysics, University of Toronto, Toronto, ON M5S 3H2, Canada
| | - Muriel Arimon
- Alzheimer Research Unit, MassGeneral Institute for Neurodegenerative Diseases, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Oksana Berezovska
- Alzheimer Research Unit, MassGeneral Institute for Neurodegenerative Diseases, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Bradley T Hyman
- Alzheimer Research Unit, MassGeneral Institute for Neurodegenerative Diseases, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Taisuke Tomita
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, and Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takeshi Iwatsubo
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, and Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Christopher M Johnson
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Lindsay A Farrer
- Departments of Medicine (Biomedical Genetics), Neurology, Ophthalmology, Genetics and Genomics, Biostatistics, and Epidemiology, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA
| | - Gerold Schmitt-Ulms
- Tanz Centre for Research in Neurodegenerative Diseases, and Departments of Medicine, Laboratory Medicine and Pathobiology, and Medical Biophysics, University of Toronto, Toronto, ON M5S 3H2, Canada
| | - Paul E Fraser
- Tanz Centre for Research in Neurodegenerative Diseases, and Departments of Medicine, Laboratory Medicine and Pathobiology, and Medical Biophysics, University of Toronto, Toronto, ON M5S 3H2, Canada
| | - Peter H St George-Hyslop
- Department of Clinical Neurosciences, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK; Tanz Centre for Research in Neurodegenerative Diseases, and Departments of Medicine, Laboratory Medicine and Pathobiology, and Medical Biophysics, University of Toronto, Toronto, ON M5S 3H2, Canada.
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149
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Crowe SE, Ellis-Davies GCR. In vivo characterization of a bigenic fluorescent mouse model of Alzheimer's disease with neurodegeneration. J Comp Neurol 2013; 521:2181-94. [PMID: 23348594 DOI: 10.1002/cne.23306] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 12/14/2012] [Accepted: 01/17/2013] [Indexed: 11/11/2022]
Abstract
The loss of cognitive function in Alzheimer's disease (AD) patients is strongly correlated with the loss of neurons in various regions of the brain. We have created a new fluorescent bigenic mouse model of AD by crossing "H-line" yellow fluorescent protein (YFP) mice with the 5xFAD mouse model, which we call the 5XY mouse model. The 5xFAD mouse has been shown to have significant loss of L5 pyramidal neurons by 12 months of age. These neurons are transgenically labeled with YFP in the 5XY mouse, which enable longitudinal imaging of structural changes. In the 5XY mice, we observed an appearance of axonal dystrophies, with two distinct morphologies in the early stages of the disease progression. Simple swelling dystrophies are transient in nature and are not directly associated with amyloid plaques. Rosette dystrophies are more complex structures that remained stable throughout all imaging sessions, and always surrounded an amyloid plaque. Plaque growth was followed over 4 weeks, and significant growth was seen between weekly imaging sessions. In addition to axonal dystrophy appearance and plaque growth, we were able to follow spine stability in 4-month old 5XY mice, which revealed no significant loss of spines. 5XY mice also showed a striking shrinkage of the neocortex at older ages (12-14 months). The 5XY mouse model may be a valuable tool for studying specific events in the degeneration of the neocortex, and may suggest new avenues for therapeutic intervention.
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Affiliation(s)
- Sarah E Crowe
- Department of Neuroscience, Mount Sinai School of Medicine, New York, New York 10029, USA
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150
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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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