1
|
Liu H, Xie Y, Wang X, Abboud MI, Ma C, Ge W, Schofield CJ. Exploring links between 2-oxoglutarate-dependent oxygenases and Alzheimer's disease. Alzheimers Dement 2022; 18:2637-2668. [PMID: 35852137 PMCID: PMC10083964 DOI: 10.1002/alz.12733] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 05/12/2022] [Accepted: 06/10/2022] [Indexed: 01/31/2023]
Abstract
Hypoxia, that is, an inadequate oxygen supply, is linked to neurodegeneration and patients with cardiovascular disease are prone to Alzheimer's disease (AD). 2-Oxoglutarate and ferrous iron-dependent oxygenases (2OGDD) play a key role in the regulation of oxygen homeostasis by acting as hypoxia sensors. 2OGDD also have roles in collagen biosynthesis, lipid metabolism, nucleic acid repair, and the regulation of transcription and translation. Many biological processes in which the >60 human 2OGDD are involved are altered in AD patient brains, raising the question as to whether 2OGDD are involved in the transition from normal aging to AD. Here we give an overview of human 2OGDD and critically discuss their potential roles in AD, highlighting possible relationships with synapse dysfunction/loss. 2OGDD may regulate neuronal/glial differentiation through enzyme activity-dependent mechanisms and modulation of their activity has potential to protect against synapse loss. Work linking 2OGDD and AD is at an early stage, especially from a therapeutic perspective; we suggest integrated pathology and in vitro discovery research to explore their roles in AD is merited. We hope to help enable long-term research on the roles of 2OGDD and, more generally, oxygen/hypoxia in AD. We also suggest shorter term empirically guided clinical studies concerning the exploration of 2OGDD/oxygen modulators to help maintain synaptic viability are of interest for AD treatment.
Collapse
Affiliation(s)
- Haotian Liu
- State Key Laboratory of Medical Molecular Biology & Department of ImmunologyInstitute of Basic Medical Sciences Chinese Academy of Medical SciencesSchool of Basic Medicine Peking Union Medical CollegeBeijingChina
| | - Yong Xie
- State Key Laboratory of Medical Molecular Biology & Department of ImmunologyInstitute of Basic Medical Sciences Chinese Academy of Medical SciencesSchool of Basic Medicine Peking Union Medical CollegeBeijingChina
- National Clinical Research Center for OrthopedicsSports Medicine & RehabilitationDepartment of OrthopedicsGeneral Hospital of Chinese PLABeijingChina
| | - Xia Wang
- State Key Laboratory of Medical Molecular Biology & Department of ImmunologyInstitute of Basic Medical Sciences Chinese Academy of Medical SciencesSchool of Basic Medicine Peking Union Medical CollegeBeijingChina
| | - Martine I. Abboud
- The Chemistry Research LaboratoryDepartment of Chemistry and the Ineos Oxford Institute for Antimicrobial ResearchUniversity of OxfordOxfordUK
| | - Chao Ma
- Department of Human Anatomy, Histology and EmbryologyNeuroscience CenterNational Human Brain Bank for Development and FunctionInstitute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
| | - Wei Ge
- State Key Laboratory of Medical Molecular Biology & Department of ImmunologyInstitute of Basic Medical Sciences Chinese Academy of Medical SciencesSchool of Basic Medicine Peking Union Medical CollegeBeijingChina
| | - Christopher J. Schofield
- The Chemistry Research LaboratoryDepartment of Chemistry and the Ineos Oxford Institute for Antimicrobial ResearchUniversity of OxfordOxfordUK
| |
Collapse
|
2
|
Cho Y, Bae HG, Okun E, Arumugam TV, Jo DG. Physiology and pharmacology of amyloid precursor protein. Pharmacol Ther 2022; 235:108122. [PMID: 35114285 DOI: 10.1016/j.pharmthera.2022.108122] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 01/17/2022] [Accepted: 01/25/2022] [Indexed: 02/06/2023]
Abstract
Amyloid precursor protein (APP) is an evolutionarily conserved transmembrane protein and a well-characterized precursor protein of amyloid-beta (Aβ) peptides, which accumulate in the brains of individuals with Alzheimer's disease (AD)-related pathologies. Aβ has been extensively investigated since the amyloid hypothesis in AD was proposed. Besides Aβ, previous studies on APP and its proteolytic cleavage products have suggested their diverse pathological and physiological functions. However, their roles still have not been thoroughly understood. In this review, we extensively discuss the evolutionarily-conserved biology of APP, including its structure and processing pathway, as well as recent findings on the physiological roles of APP and its fragments in the central nervous system and peripheral nervous system. We have also elaborated upon the current status of APP-targeted therapeutic approaches for AD treatment by discussing inhibitors of several proteases participating in APP processing, including α-, β-, and γ-secretases. Finally, we have highlighted the future perspectives pertaining to further research and the potential clinical role of APP.
Collapse
Affiliation(s)
- Yoonsuk Cho
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, South Korea
| | - Han-Gyu Bae
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, South Korea
| | - Eitan Okun
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan 5290002, Israel; The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 5290002, Israel; The Pauld Feder Laboratory on Alzheimer's Disease Research, Israel
| | - Thiruma V Arumugam
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, South Korea; School of Life Sciences, La Trobe University, Bundoora, Victoria, Australia.
| | - Dong-Gyu Jo
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, South Korea; Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 06351, South Korea; Biomedical Institute for Convergence, Sungkyunkwan University, Suwon 16419, South Korea.
| |
Collapse
|
3
|
Bernabeu-Zornoza A, Coronel R, Palmer C, Monteagudo M, Zambrano A, Liste I. Physiological and pathological effects of amyloid-β species in neural stem cell biology. Neural Regen Res 2019; 14:2035-2042. [PMID: 31397330 PMCID: PMC6788229 DOI: 10.4103/1673-5374.262571] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 04/03/2019] [Indexed: 12/17/2022] Open
Abstract
Although amyloid-β peptide is considered neurotoxic, it may mediate several physiological processes during embryonic development and in the adult brain. The pathological function of amyloid-β peptide has been extensively studied due to its implication in Alzheimer's disease, but its physiological function remains poorly understood. Amyloid-β peptide can be detected in non-aggregated (monomeric) and aggregated (oligomeric and fibrillary) forms. Each form has different cytotoxic and/or physiological properties, so amyloid-β peptide and its role in Alzheimer's disease need to be studied further. Neural stem cells and neural precursor cells are good tools for the study on neurodegenerative diseases and can provide future therapeutic applications in diseases such as Alzheimer's disease. In this review, we provide an outline of the effects of amyloid-β peptide, in monomeric and aggregated forms, on the biology of neural stem cells/neural precursor cells, and discuss the controversies. We also describe the possible molecular targets that could be implicated in these effects, especially GSK3β. A better understanding of amyloid-β peptide (both physiological and pathological), and the signaling pathways involved are essential to advance the field of Alzheimer's disease.
Collapse
Affiliation(s)
- Adela Bernabeu-Zornoza
- Unidad de Regeneración Neural, Unidad Funcional de Investigación de Enfermedades Crónicas. Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Raquel Coronel
- Unidad de Regeneración Neural, Unidad Funcional de Investigación de Enfermedades Crónicas. Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Charlotte Palmer
- Unidad de Regeneración Neural, Unidad Funcional de Investigación de Enfermedades Crónicas. Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - María Monteagudo
- Unidad de Regeneración Neural, Unidad Funcional de Investigación de Enfermedades Crónicas. Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Alberto Zambrano
- Unidad de Regeneración Neural, Unidad Funcional de Investigación de Enfermedades Crónicas. Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| | - Isabel Liste
- Unidad de Regeneración Neural, Unidad Funcional de Investigación de Enfermedades Crónicas. Instituto de Salud Carlos III (ISCIII), Majadahonda, Madrid, Spain
| |
Collapse
|
4
|
Castro MA, Hadziselimovic A, Sanders CR. The vexing complexity of the amyloidogenic pathway. Protein Sci 2019; 28:1177-1193. [PMID: 30897251 PMCID: PMC6566549 DOI: 10.1002/pro.3606] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 03/18/2019] [Accepted: 03/18/2019] [Indexed: 02/06/2023]
Abstract
The role of the amyloidogenic pathway in the etiology of Alzheimer's disease (AD), particularly the common sporadic late onset forms of the disease, is controversial. To some degree, this is a consequence of the failure of drug and therapeutic antibody trials based either on targeting the proteases in this pathway or its amyloid end products. Here, we explore the formidable complexity of the biochemistry and cell biology associated with this pathway. For example, we review evidence that the immediate precursor of amyloid-β, the C99 domain of the amyloid precursor protein (APP), may itself be toxic. We also review important new results that appear to finally establish a direct genetic link between mutations in APP and the sporadic forms of AD. Based on the complexity of amyloidogenesis, it seems possible that a major contributor to the failure of related drug trials is that we have an incomplete understanding of this pathway and how it is linked to Alzheimer's pathogenesis. If so, this highlights a need for further characterization of this pathway, not its abandonment.
Collapse
Affiliation(s)
- Manuel A. Castro
- Departments of Biochemistry and MedicineVanderbilt University School of MedicineNashvilleTennessee 37240
| | - Arina Hadziselimovic
- Departments of Biochemistry and MedicineVanderbilt University School of MedicineNashvilleTennessee 37240
| | - Charles R. Sanders
- Departments of Biochemistry and MedicineVanderbilt University School of MedicineNashvilleTennessee 37240
| |
Collapse
|
5
|
Krasinski CA, Zheng Q, Ivancic VA, Spratt DE, Lazo ND. The Longest Amyloid-β Precursor Protein Intracellular Domain Produced with Aβ42 Forms β-Sheet-Containing Monomers That Self-Assemble and Are Proteolyzed by Insulin-Degrading Enzyme. ACS Chem Neurosci 2018; 9:2892-2897. [PMID: 30067897 DOI: 10.1021/acschemneuro.8b00305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disease resulting in dementia. It is characterized pathologically by extracellular amyloid plaques composed mainly of deposited Aβ42 and intracellular neurofibrillary tangles formed by hyperphosphorylated tau protein. Recent clinical trials targeting Aβ have failed, suggesting that other polypeptides produced from the amyloid-β precursor protein (APP) may be involved in AD. An attractive polypeptide is AICD57, the longest APP intracellular domain (AICD) coproduced with Aβ42. Here, we show that AICD57 forms micelle-like assemblies that are proteolyzed by insulin-degrading enzyme (IDE), indicating that AICD57 monomers are in dynamic equilibrium with AICD57 assemblies. The N-terminal part of AICD57 monomer is not degraded, but its C-terminal part is hydrolyzed, particularly in the YENPTY motif that has been associated with the hyperphosphorylation of tau. Therefore, sustaining IDE activity well into old age holds promise for regulating levels of not only Aβ but also AICD in the aging brain.
Collapse
Affiliation(s)
- Claire A. Krasinski
- Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, Massachusetts 01610, United States
| | - Qiuchen Zheng
- Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, Massachusetts 01610, United States
| | - Valerie A. Ivancic
- Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, Massachusetts 01610, United States
| | - Donald E. Spratt
- Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, Massachusetts 01610, United States
| | - Noel D. Lazo
- Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, Massachusetts 01610, United States
| |
Collapse
|
6
|
Role of Amyloid Precursor Protein (APP) and Its Derivatives in the Biology and Cell Fate Specification of Neural Stem Cells. Mol Neurobiol 2018; 55:7107-7117. [DOI: 10.1007/s12035-018-0914-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/18/2018] [Indexed: 01/31/2023]
|
7
|
Small things matter: Implications of APP intracellular domain AICD nuclear signaling in the progression and pathogenesis of Alzheimer’s disease. Prog Neurobiol 2017; 156:189-213. [DOI: 10.1016/j.pneurobio.2017.05.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/25/2017] [Accepted: 05/30/2017] [Indexed: 01/08/2023]
|
8
|
Salminen A, Kauppinen A, Kaarniranta K. Hypoxia/ischemia activate processing of Amyloid Precursor Protein: impact of vascular dysfunction in the pathogenesis of Alzheimer's disease. J Neurochem 2017; 140:536-549. [DOI: 10.1111/jnc.13932] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 12/05/2016] [Accepted: 12/10/2016] [Indexed: 12/13/2022]
Affiliation(s)
- Antero Salminen
- Department of Neurology; Institute of Clinical Medicine; University of Eastern Finland; Kuopio Finland
| | - Anu Kauppinen
- School of Pharmacy; Faculty of Health Sciences; University of Eastern Finland; Kuopio Finland
| | - Kai Kaarniranta
- Department of Ophthalmology; Institute of Clinical Medicine; University of Eastern Finland; Kuopio Finland
- Department of Ophthalmology; Kuopio University Hospital; Kuopio Finland
| |
Collapse
|
9
|
Khanna MR, Fortini ME. Transcriptomic Analysis of Drosophila Mushroom Body Neurons Lacking Amyloid-β Precursor-Like Protein Activity. J Alzheimers Dis 2016; 46:913-28. [PMID: 26402626 DOI: 10.3233/jad-141491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The amyloid-β protein precursor (AβPP) is subjected to sequential intramembrane proteolysis by α-, β-, andγ-secretases, producing secreted amyloid-β (Aβ) peptides and a cytoplasmically released AβPP Intracellular Domain (AICD). AICD complexes with transcription factors in the nucleus, suggesting that this AβPP fragment serves as an active signaling effector that regulates downstream genes, although its nuclear targets are poorly defined. To further understand this potential signaling mechanism mediated by AβPP, we performed a transcriptomic identification of the Drosophila genome that is regulated by the fly AβPP orthologue in fly mushroom body neurons, which control learning- and memory-based behaviors. We find significant changes in expression of 245 genes, representing approximately 1.6% of the Drosophila genome, with the changes ranging from +6 fold to -40 fold. The largest class of responsive targets corresponds to non-protein coding genes and includes microRNAs that have been previously implicated in Alzheimer's disease pathophysiology. Several genes were identified in our Drosophila microarray analyses that have also emerged as putative AβPP targets in similar mammalian transcriptomic studies. Our results also indicate a role for AβPP in cellular pathways involving the regulation of Drosophila Casein Kinase II, mitochondrial oxidative phosphorylation, RNA processing, and innate immunity. Our findings provide insights into the intracellular events that are regulated by AβPP activity in healthy neurons and that might become dysregulated as a result of abnormal AβPP proteolysis in AD.
Collapse
|
10
|
Puzzo D, Gulisano W, Arancio O, Palmeri A. The keystone of Alzheimer pathogenesis might be sought in Aβ physiology. Neuroscience 2015; 307:26-36. [PMID: 26314631 PMCID: PMC4591241 DOI: 10.1016/j.neuroscience.2015.08.039] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/15/2015] [Accepted: 08/18/2015] [Indexed: 01/17/2023]
Abstract
For several years Amyloid-beta peptide (Aβ) has been considered the main pathogenetic factor of Alzheimer's disease (AD). According to the so called Amyloid Cascade Hypothesis the increase of Aβ triggers a series of events leading to synaptic dysfunction and memory loss as well as to the structural brain damage in the later stage of the disease. However, several evidences suggest that this hypothesis is not sufficient to explain AD pathogenesis, especially considering that most of the clinical trials aimed to decrease Aβ levels have been unsuccessful. Moreover, Aβ is physiologically produced in the healthy brain during neuronal activity and it is needed for synaptic plasticity and memory. Here we propose a model interpreting AD pathogenesis as an alteration of the negative feedback loop between Aβ and its physiological receptors, focusing on alpha7 nicotinic acetylcholine receptors (α7-nAchRs). According to this vision, when Aβ cannot exert its physiological function a negative feedback mechanism would induce a compensatory increase of its production leading to an abnormal accumulation that reduces α7-nAchR function, leading to synaptic dysfunction and memory loss. In this perspective, the indiscriminate Aβ removal might worsen neuronal homeostasis, causing a further impoverishment of learning and memory. Even if further studies are needed to better understand and validate these mechanisms, we believe that to deepen the role of Aβ in physiological conditions might represent the keystone to elucidate important aspects of AD pathogenesis.
Collapse
Affiliation(s)
- D Puzzo
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, Viale A. Doria 6 (ed. 2), University of Catania, Catania 95125, Italy.
| | - W Gulisano
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, Viale A. Doria 6 (ed. 2), University of Catania, Catania 95125, Italy
| | - O Arancio
- Department of Pathology and Cell Biology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, 630 West 168th Street, Columbia University, New York, NY 10032, USA
| | - A Palmeri
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, Viale A. Doria 6 (ed. 2), University of Catania, Catania 95125, Italy
| |
Collapse
|
11
|
Melnyk P, Vingtdeux V, Burlet S, Eddarkaoui S, Grosjean ME, Larchanché PE, Hochart G, Sergheraert C, Estrella C, Barrier M, Poix V, Plancq P, Lannoo C, Hamdane M, Delacourte A, Verwaerde P, Buée L, Sergeant N. Chloroquine and chloroquinoline derivatives as models for the design of modulators of amyloid Peptide precursor metabolism. ACS Chem Neurosci 2015; 6:559-69. [PMID: 25611616 DOI: 10.1021/cn5003013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The amyloid precursor protein (APP) plays a central role in Alzheimer's disease (AD). Preventing deregulated APP processing by inhibiting amyloidogenic processing of carboxy-terminal fragments (APP-CTFs), and reducing the toxic effect of amyloid beta (Aβ) peptides remain an effective therapeutic strategy. We report the design of piperazine-containing compounds derived from chloroquine structure and evaluation of their effects on APP metabolism and ability to modulate the processing of APP-CTF and the production of Aβ peptide. Compounds which retained alkaline properties and high affinity for acidic cell compartments were the most effective. The present study demonstrates that (1) the amino side chain of chloroquine can be efficiently substituted by a bis(alkylamino)piperazine chain, (2) the quinoline nucleus can be replaced by a benzyl or a benzimidazole moiety, and (3) pharmacomodulation of the chemical structure allows the redirection of APP metabolism toward a decrease of Aβ peptide release, and increased stability of APP-CTFs and amyloid intracellular fragment. Moreover, the benzimidazole compound 29 increases APP-CTFs in vivo and shows promising activity by the oral route. Together, this family of compounds retains a lysosomotropic activity which inhibits lysosome-related Aβ production, and is likely to be beneficial for therapeutic applications in AD.
Collapse
Affiliation(s)
- Patricia Melnyk
- Université de Lille, F-59000 Lille, France
- UDSL, EA 4481,
UFR Pharmacie, F-59000 Lille, France
- CNRS UMR8161, F-59000 Lille, France
| | - Valérie Vingtdeux
- Université de Lille, F-59000 Lille, France
- Inserm UMR-S1172, Alzheimer & Tauopathies, Jean-Pierre Aubert Research Center, F-59000 Lille, France
| | | | - Sabiha Eddarkaoui
- Université de Lille, F-59000 Lille, France
- Inserm UMR-S1172, Alzheimer & Tauopathies, Jean-Pierre Aubert Research Center, F-59000 Lille, France
| | - Marie-Eve Grosjean
- Université de Lille, F-59000 Lille, France
- Inserm UMR-S1172, Alzheimer & Tauopathies, Jean-Pierre Aubert Research Center, F-59000 Lille, France
| | | | - Guillaume Hochart
- Université de Lille, F-59000 Lille, France
- UDSL, EA 4481,
UFR Pharmacie, F-59000 Lille, France
- CNRS UMR8161, F-59000 Lille, France
| | | | | | | | | | | | | | - Malika Hamdane
- Université de Lille, F-59000 Lille, France
- Inserm UMR-S1172, Alzheimer & Tauopathies, Jean-Pierre Aubert Research Center, F-59000 Lille, France
| | - André Delacourte
- Université de Lille, F-59000 Lille, France
- Inserm UMR-S1172, Alzheimer & Tauopathies, Jean-Pierre Aubert Research Center, F-59000 Lille, France
| | | | - Luc Buée
- Université de Lille, F-59000 Lille, France
- Inserm UMR-S1172, Alzheimer & Tauopathies, Jean-Pierre Aubert Research Center, F-59000 Lille, France
| | - Nicolas Sergeant
- Université de Lille, F-59000 Lille, France
- Inserm UMR-S1172, Alzheimer & Tauopathies, Jean-Pierre Aubert Research Center, F-59000 Lille, France
| |
Collapse
|
12
|
Abstract
Neuronal apoptosis represents an intrinsic «suicide» program, by which a neuron orchestrates its own destruction. Although engagement of apoptosis requires transcription and protein synthesis, the complete spectrum of genes involved in distinct temporal domains remained unknown until the advent of genomics. In the last 10 years, the genome sequences and the development of high-throughput genomic technologies, such as DNA microarrays, have offered the unprecedented experimental opportunities to explore the transcriptional mechanisms underlying apoptosis from a new systems-level perspective. This review goes over this genomic approach and illustrates the use of microarray methodology to dissecting the multigenic program underlying neuronal apoptosis.
Collapse
Affiliation(s)
- Sebastiano Cavallaro
- Functional Genomics Center, Institute of Neurological Sciences, Italian National Research Council (CNR), Via Paolo Gaifami 18, Catania, 95126, Italy,
| |
Collapse
|
13
|
Kametani F, Haga S. Accumulation of carboxy-terminal fragments of APP increases phosphodiesterase 8B. Neurobiol Aging 2014; 36:634-7. [PMID: 25457556 DOI: 10.1016/j.neurobiolaging.2014.09.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 09/19/2014] [Accepted: 09/30/2014] [Indexed: 11/17/2022]
Abstract
The long-standing "amyloid hypothesis" that Alzheimer's disease is caused by the production and aggregation of amyloid-β faces serious challenges by data recently obtained from neuroimaging studies and amyloid-β amyloid-focused clinical trials. Meanwhile, accumulation of carboxy-terminal fragments (CTFs) of the amyloid precursor protein (APP) may be neurotoxic and may impair synaptic plasticity and long-term memory in Alzheimer's disease, as suggested in murine models. To clarify these issues, we carried out a proteomic analysis of Chinese hamster ovary cells expressing APP CTFs and found that APP-CTF accumulation induced an increase in the level of phosphodiesterase 8B, suggesting that the hydrolysis of cyclic AMP was enhanced.
Collapse
Affiliation(s)
- Fuyuki Kametani
- Department of Dementia and Higher Brain Function, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
| | - Seiichi Haga
- Department of Dementia and Higher Brain Function, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| |
Collapse
|
14
|
Altered Levels of Amyloid Precursor Protein Intracellular Domain-interacting Proteins in Alzheimer Disease. Alzheimer Dis Assoc Disord 2014; 28:283-90. [DOI: 10.1097/wad.0000000000000011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
15
|
Wang J, Yan K, Wu ZQ, Zheng CY, Xu RX, Chen LH, Wen ZM, Zhao HQ, Ma QH. TDP-43 interaction with the intracellular domain of amyloid precursor protein induces p53-associated apoptosis. Neurosci Lett 2014; 569:131-6. [DOI: 10.1016/j.neulet.2014.03.075] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 03/10/2014] [Accepted: 03/29/2014] [Indexed: 12/13/2022]
|
16
|
Hicks DA, Makova NZ, Gough M, Parkin ET, Nalivaeva NN, Turner AJ. The amyloid precursor protein represses expression of acetylcholinesterase in neuronal cell lines. J Biol Chem 2013; 288:26039-26051. [PMID: 23897820 DOI: 10.1074/jbc.m113.461269] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The toxic role of amyloid β peptides in Alzheimer's disease is well documented. Their generation is via sequential β- and γ-secretase cleavage of the membrane-bound amyloid precursor protein (APP). Other APP metabolites include the soluble ectodomains sAPPα and sAPPβ and also the amyloid precursor protein intracellular domain (AICD). In this study, we examined whether APP is involved in the regulation of acetylcholinesterase (AChE), which is a key protein of the cholinergic system and has been shown to accelerate amyloid fibril formation and increase their toxicity. Overexpression of the neuronal specific isoform, APP695, in the neuronal cell lines SN56 and SH-SY5Y substantially decreased levels of AChE mRNA, protein, and catalytic activity. Although similar decreases in mRNA levels were observed of the proline-rich anchor of AChE, PRiMA, no changes were seen in mRNA levels of the related enzyme, butyryl-cholinesterase, nor of the high-affinity choline transporter. A γ-secretase inhibitor did not affect AChE transcript levels or enzyme activity in SN56 (APP695) or SH-SY5Y (APP695) cells, showing that regulation of AChE by APP does not require the generation of AICD or amyloid β peptide. Treatment of wild-type SN56 cells with siRNA targeting APP resulted in a significant up-regulation in AChE mRNA levels. Mutagenesis studies suggest that the observed transcriptional repression of AChE is mediated by the E1 region of APP, specifically its copper-binding domain, but not the C-terminal YENTPY motif. In conclusion, AChE is regulated in two neuronal cell lines by APP in a manner independent of the generation of sAPPα, sAPPβ, and AICD.
Collapse
Affiliation(s)
- David A Hicks
- From the School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Natalia Z Makova
- From the School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Mallory Gough
- the Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YQ, United Kingdom, and
| | - Edward T Parkin
- the Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YQ, United Kingdom, and
| | - Natalia N Nalivaeva
- From the School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom,; the I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Anthony J Turner
- From the School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom,.
| |
Collapse
|
17
|
Delvaux E, Bentley K, Stubbs V, Sabbagh M, Coleman PD. Differential processing of amyloid precursor protein in brain and in peripheral blood leukocytes. Neurobiol Aging 2013; 34:1680-6. [PMID: 23298733 DOI: 10.1016/j.neurobiolaging.2012.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 12/06/2012] [Accepted: 12/06/2012] [Indexed: 12/17/2022]
Abstract
Because amyloid precursor protein (APP) fragments exist in many tissues throughout the body, including the fluid compartments of blood, they have been the focus of numerous investigations into their potential as a biomarker of Alzheimer's disease. Using immunohistochemistry, immunoelectron microscopy, Western blot, and quantitative real-time-polymerase chain reaction (qRT-PCR) analysis we examined whether APP processing in leukocytes is analogous to APP processing in the brain. We show APP immunoreactivity at light and electron microscopic levels in the cytoplasm and nucleus of peripheral blood leukocytes (PBL) yet our Western blot analysis data demonstrated that brain and PBL contain different APP fragments and differentially expressed APP processing enzymes. A Disintegrin and Metalloproteinase domain 10 (ADAM10), nicastrin, and beta-secretase 2 (BACE2) were present in brain but were undetected in PBL. Presenilin 1 and beta-secretase 1 (BACE1) were detected in both tissues but showed different patterns in Western blots. Quantitative PCR results identified Neprilysin as the only processing enzyme we interrogated in which Western and quantitative PCR data coincided. Although our data on differential processing of APP in brain and PBL point to exercising caution when generalizing between blood and brain with regard to mechanisms, they have no implications regarding utility as biomarkers.
Collapse
Affiliation(s)
- Elaine Delvaux
- L.J. Roberts Center for Alzheimer's Research, Banner Sun Health Research Institute, Sun City, AZ, USA.
| | | | | | | | | |
Collapse
|
18
|
El Ayadi A, Stieren ES, Barral JM, Oberhauser AF, Boehning D. Purification and aggregation of the amyloid precursor protein intracellular domain. J Vis Exp 2012:e4204. [PMID: 22952038 DOI: 10.3791/4204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Amyloid precursor protein (APP) is a type I transmembrane protein associated with the pathogenesis of Alzheimer's disease (AD). APP is characterized by a large extracellular domain and a short cytosolic domain termed the APP intracellular domain (AICD). During maturation through the secretory pathway, APP can be cleaved by proteases termed α, β, and γ-secretases. Sequential proteolytic cleavage of APP with β and γ-secretases leads to the production of a small proteolytic peptide, termed Aβ, which is amyloidogenic and the core constituent of senile plaques. The AICD is also liberated from the membrane after secretase processing, and through interactions with Fe65 and Tip60, can translocate to the nucleus to participate in transcription regulation of multiple target genes. Protein-protein interactions involving the AICD may affect trafficking, processing, and cellular functions of holo-APP and its C-terminal fragments. We have recently shown that AICD can aggregate in vitro, and this process is inhibited by the AD-implicated molecular chaperone ubiquilin-1. Consistent with these findings, the AICD has exposed hydrophobic domains and is intrinsically disordered in vitro, however it obtains stable secondary structure when bound to Fe65. We have proposed that ubiquilin-1 prevents inappropriate inter- and intramolecular interactions of AICD, preventing aggregation in vitro and in intact cells. While most studies focus on the role of APP in the pathogenesis of AD, the role of AICD in this process is not clear. Expression of AICD has been shown to induce apoptosis, to modulate signaling pathways, and to regulate calcium signaling. Over-expression of AICD and Fe65 in a transgenic mouse model induces Alzheimer's like pathology, and recently AICD has been detected in brain lysates by western blotting when using appropriate antigen retrieval techniques. To facilitate structural, biochemical, and biophysical studies of the AICD, we have developed a procedure to produce recombinantly large amounts of highly pure AICD protein. We further describe a method for inducing the in vitro thermal aggregation of AICD and analysis by atomic force microscopy. The methods described are useful for biochemical, biophysical, and structural characterization of the AICD and the effects of molecular chaperones on AICD aggregation.
Collapse
Affiliation(s)
- Amina El Ayadi
- Department of Surgery, University of Texas Medical Branch, USA
| | | | | | | | | |
Collapse
|
19
|
Lazarov O, Demars MP. All in the Family: How the APPs Regulate Neurogenesis. Front Neurosci 2012; 6:81. [PMID: 22675290 PMCID: PMC3366480 DOI: 10.3389/fnins.2012.00081] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 05/14/2012] [Indexed: 12/23/2022] Open
Abstract
Recent intriguing evidence suggests that metabolites of amyloid precursor protein (APP), mutated in familial forms of Alzheimer’s disease (AD), play critical roles in developmental and postnatal neurogenesis. Of note is soluble APPα (sAPPα) that regulates neural progenitor cell proliferation. The APP family encompasses a group of ubiquitously expressed and evolutionarily conserved, type I transmembrane glycoproteins, whose functions have yet to be fully elucidated. APP can undergo proteolytic cleavage by mutually exclusive pathways. The subtle structural differences between metabolites generated in the different pathways, as well as their equilibrium, may be crucial for neuronal function. The implications of this new body of evidence are significant. Miscleavage of APP would readily impact developmental and postnatal neurogenesis, which might contribute to cognitive deficits characterizing Alzheimer’s disease. This review will discuss the implications of the role of the APP family in neurogenesis for neuronal development, cognitive function, and brain disorders that compromise learning and memory, such as AD.
Collapse
Affiliation(s)
- Orly Lazarov
- Department of Anatomy and Cell Biology, College of Medicine, The University of Illinois at Chicago Chicago, IL, USA
| | | |
Collapse
|
20
|
Jellinger KA. Interaction between pathogenic proteins in neurodegenerative disorders. J Cell Mol Med 2012; 16:1166-83. [PMID: 22176890 PMCID: PMC3823071 DOI: 10.1111/j.1582-4934.2011.01507.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 12/16/2011] [Indexed: 12/21/2022] Open
Abstract
The misfolding and progressive aggregation of specific proteins in selective regions of the nervous system is a seminal occurrence in many neurodegenerative disorders, and the interaction between pathological/toxic proteins to cause neurodegeneration is a hot topic of current neuroscience research. Despite clinical, genetic and experimental differences, increasing evidence indicates considerable overlap between synucleinopathies, tauopathies and other protein-misfolding diseases. Inclusions, often characteristic hallmarks of these disorders, suggest interactions of pathological proteins enganging common downstream pathways. Novel findings that have shifted our understanding in the role of pathologic proteins in the pathogenesis of Alzheimer, Parkinson, Huntington and prion diseases, have confirmed correlations/overlaps between these and other neurodegenerative disorders. Emerging evidence, in addition to synergistic effects of tau protein, amyloid-β, α-synuclein and other pathologic proteins, suggests that prion-like induction and spreading, involving secreted proteins, are major pathogenic mechanisms in various neurodegenerative diseases, depending on genetic backgrounds and environmental factors. The elucidation of the basic molecular mechanisms underlying the interaction and spreading of pathogenic proteins, suggesting a dualism or triad of neurodegeneration in protein-misfolding disorders, is a major challenge for modern neuroscience, to provide a deeper insight into their pathogenesis as a basis of effective diagnosis and treatment.
Collapse
|
21
|
Amyloid precursor protein binding protein-1 knockdown reduces neuronal differentiation in fetal neural stem cells. Neuroreport 2012; 23:61-6. [PMID: 22182960 DOI: 10.1097/wnr.0b013e32834e7d4f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Amyloid precursor protein binding protein-1 (APP-BP1) was first identified as an interacting protein of APP. In this study, we explored whether APP-BP1 plays a role in neuronal differentiation of fetal neural stem cells. APP-BP1 knockdown by small interfering RNA treatment was found to downregulate neuronal differentiation and to upregulate APP intracellular domain production from APP in fetal neural stem cells. Furthermore, the change in gene expression profiles was systemically examined by DNA microarray. The expression of several genes including ephrin A2 was upregulated by APP-BP1 knockdown as assessed with DNA microarray and reverse transcriptase-polymerase chain reaction. Taken together, our results suggest that APP-BP1 modulates neuronal differentiation by altering gene expression profiles in fetal neural stem cells.
Collapse
|
22
|
Pardossi-Piquard R, Checler F. The physiology of the β-amyloid precursor protein intracellular domain AICD. J Neurochem 2011; 120 Suppl 1:109-124. [PMID: 22122663 DOI: 10.1111/j.1471-4159.2011.07475.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The amyloid-β precursor protein (βAPP) undergoes several cleavages by enzymatic activities called secretases. Numerous studies aimed at studying the biogenesis and catabolic fate of Aβ peptides, the proteinaceous component of the senile plaques that accumulate in Alzheimer's disease-affected brains. Relatively recently, another secretase-mediated β-APP-derived catabolite called APP IntraCellular Domain (AICD) entered the game. Whether AICD corresponded to a biologically inert by-pass product of βAPP processing or whether it could harbor its own function remained questionable. In this study, we review the mechanisms by which AICD is generated and how its production is regulated. Furthermore, we discuss the degradation mechanism underlying its rapid catabolic fate. Finally, we review putative AICD-related functions and more particularly, the numerous studies indicating that AICD could translocate to the nucleus and control at a transcriptional level, the expression of a series of proteins involved in various functions including the control of cell death and Aβ degradation.
Collapse
Affiliation(s)
- Raphaëlle Pardossi-Piquard
- Université de Nice Sophia-Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire UMR6097 CNRS, Equipe labellisée Fondation pour la Recherche Médicale, Sophia-Antipolis, Valbonne, France
| | - Frédéric Checler
- Université de Nice Sophia-Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire UMR6097 CNRS, Equipe labellisée Fondation pour la Recherche Médicale, Sophia-Antipolis, Valbonne, France
| |
Collapse
|
23
|
Nuclear signalling by membrane protein intracellular domains: the AICD enigma. Cell Signal 2011; 24:402-409. [PMID: 22024280 DOI: 10.1016/j.cellsig.2011.10.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 10/10/2011] [Indexed: 01/13/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative illness and the leading cause of dementia in the elderly. The accumulation of amyloid-β peptide (Aβ) is a well-known pathological hallmark associated with the disease. However, Aβ is only one of several metabolites produced by β- and γ-secretase actions on the transmembrane protein, the amyloid precursor protein (APP). A proteolytic fragment termed the APP intracellular domain (AICD) is also produced. By analogy with the Notch signalling pathway, AICD has been proposed as a transcriptional regulator although its mechanism of action and the complement of genes regulated remain controversial. This review will focus on the contributions that studies of APP processing have brought to the understanding of a novel nuclear signalling pathway that may contribute to the pathology of AD and may provide new therapeutic opportunities.
Collapse
|
24
|
The role of lipoprotein receptors on the physiological function of APP. Exp Brain Res 2011; 217:377-87. [PMID: 21947084 DOI: 10.1007/s00221-011-2876-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 09/09/2011] [Indexed: 12/26/2022]
Abstract
In this review, we will primarily focus on the role of members of the low-density lipoprotein receptor (LDL-R) family that are involved in trafficking and processing of the amyloid precursor protein (APP). We will discuss the role of the LDL-receptor family members, low-density lipoprotein receptor-related protein 1 (LRP1), LRP1b, apolipoprotein E receptor 2, sortilin-related receptor (SorLA/LR11) and megalin/LRP2 on the physiological function of APP and its cellular localization. Additionally, we will focus on adaptor proteins that have been shown to influence the physiological function of LDL-R family members in combination with APP processing. The results in this review emphasize that the physiological function of APP cannot be explained by the focus on the APP protein alone but rather in combination with various direct or indirect interaction partners within the cellular environment.
Collapse
|
25
|
Oh Y, Kim EY, Kim Y, Jin J, Jin BK, Jahng GH, Jung MH, Park C, Kang I, Ha J, Choe W. Neuroprotective effects of overexpressed cyclophilin B against Aβ-induced neurotoxicity in PC12 cells. Free Radic Biol Med 2011; 51:905-20. [PMID: 21683784 DOI: 10.1016/j.freeradbiomed.2011.05.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 05/16/2011] [Accepted: 05/24/2011] [Indexed: 11/28/2022]
Abstract
Accumulated amyloid-β (Aβ) is a well-known cause of neuronal apoptosis in Alzheimer disease and functions in part by generating oxidative stress. Our previous work suggested that cyclophilin B (CypB) protects against endoplasmic reticulum (ER) stress. Therefore, in this study we examined the ability of CypB to protect against Aβ toxicity. CypB is present in the neurons of rat and mouse brains, and treating neural cells with Aβ(25-35) mediates apoptotic cell death. Aβ(25-35)-induced neuronal toxicity was inhibited by the overexpression of CypB as measured by cell viability, apoptotic morphology, sub-G1 cell population, intracellular reactive oxygen species accumulation, activated caspase-3, PARP cleavage, Bcl-2 proteins, mitogen-activated protein kinase (MAPK) activation, and phosphoinositide 3-kinase (PI-3-K) activation. CypB/R95A PPIase mutants did not reduce Aβ(25-35) toxicity. We showed that Aβ(25-35)-induced apoptosis is more severe in a CypB knockdown model, confirming that CypB protects against Aβ(25-35)-induced toxicity. Consequently, these findings suggest that CypB may protect against Aβ toxicity by its antioxidant properties, by regulating MAPK and PI-3-K signaling, and through the ER stress pathway.
Collapse
Affiliation(s)
- Yoojung Oh
- Medical Science and Engineering Research Center for Bioreaction to Reactive Oxygen Species, Biomedical Science Institute (BK-21), Kyung Hee University, Seoul 134-727, Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Abstract
Neurological disease, and in particular neurodegenerative diseases, cause significant burdens on both patient and healthcare costs. Despite extensive research, treatment options for patients with these conditions remain limited, and generally, only provide modest symptomatic relief. Aberrant epigenetic post-translational modifications of proteins are emerging as important elements in the pathogenesis of neurological disease. Using Alzheimer’s disease and Huntington’s disease as examples in the following article, some of latest data linking both the histone code and the various proteins that regulate this code to the pathogenesis of neurological disease are discussed. The current evidence suggesting that pharmacologically targeting one such family, the histone deacetylases, may be of potential benefit in the treatment of such diseases is also discussed. Finally, some of the potential mechanisms to specifically target these proteins within the neurological setting are discussed.
Collapse
Affiliation(s)
- Steven G Gray
- Translational Cancer Research Group, Department of Clinical Medicine, Institute of Molecular Medicine, Trinity Centre for Health Sciences, St James’s Hospital, James’s Street, Dublin 8, Ireland
| |
Collapse
|
27
|
γ-Secretase-regulated mechanisms similar to notch signaling may play a role in signaling events, including APP signaling, which leads to Alzheimer's disease. Cell Mol Neurobiol 2011; 31:887-900. [PMID: 21516353 DOI: 10.1007/s10571-011-9688-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 03/30/2011] [Indexed: 01/08/2023]
Abstract
Although γ-secretase was first identified as a protease that cleaves amyloid precursor protein (APP) within the transmembrane domain, thus producing Aβ peptides that are thought to be pathogenic in Alzheimer's disease (AD), its physiological functions have not been fully elucidated. In the canonical Notch signaling pathway, intramembrane cleavage by γ-secretase serves to release an intracellular domain of Notch that shows activity in the nucleus through binding to transcription factors. Many type 1 transmembrane proteins, including Notch, Delta, and APP, have recently been shown to be substrates for γ-secretase, and their intracellular domains are released from the cell membrane following cleavage by γ-secretase. The common enzyme γ-secretase modulates proteolysis and the turnover of possible signaling molecules, which has led to the attractive hypothesis that mechanisms similar to Notch signaling contribute widely to proteolysis-regulated signaling pathways. APP is also likely to have a signaling mechanism, although the physiological functions of APP have not been elucidated. Indeed, we have shown that the intracellular domain of APP alters gene expression and induces neuron-specific apoptosis. These results suggest that APP signaling responds to the onset of AD. Here, we review the possibility of γ-secretase-regulated signaling, including APP signaling, which leads to AD.
Collapse
|