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Wlodarczyk J, Bhattacharyya R, Dore K, Ho GPH, Martin DDO, Mejias R, Hochrainer K. Altered Protein Palmitoylation as Disease Mechanism in Neurodegenerative Disorders. J Neurosci 2024; 44:e1225242024. [PMID: 39358031 PMCID: PMC11450541 DOI: 10.1523/jneurosci.1225-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2024] [Revised: 07/12/2024] [Accepted: 07/16/2024] [Indexed: 10/04/2024] Open
Abstract
Palmitoylation, a lipid-based posttranslational protein modification, plays a crucial role in regulating various aspects of neuronal function through altering protein membrane-targeting, stabilities, and protein-protein interaction profiles. Disruption of palmitoylation has recently garnered attention as disease mechanism in neurodegeneration. Many proteins implicated in neurodegenerative diseases and associated neuronal dysfunction, including but not limited to amyloid precursor protein, β-secretase (BACE1), postsynaptic density protein 95, Fyn, synaptotagmin-11, mutant huntingtin, and mutant superoxide dismutase 1, undergo palmitoylation, and recent evidence suggests that altered palmitoylation contributes to the pathological characteristics of these proteins and associated disruption of cellular processes. In addition, dysfunction of enzymes that catalyze palmitoylation and depalmitoylation has been connected to the development of neurological disorders. This review highlights some of the latest advances in our understanding of palmitoylation regulation in neurodegenerative diseases and explores potential therapeutic implications.
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Affiliation(s)
- Jakub Wlodarczyk
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw 02-093, Poland
| | - Raja Bhattacharyya
- Genetics and Aging Research Unit, Department of Neurology, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Kim Dore
- Department of Neurosciences, Center for Neural Circuits and Behavior, UCSD, La Jolla, California 92093
| | - Gary P H Ho
- Department of Neurology, Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115
| | - Dale D O Martin
- Department of Biology, Faculty of Science, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Rebeca Mejias
- Department of Physiology, School of Biology, Universidad de Sevilla, Seville, 41012 Spain
- Instituto de Investigaciones Biomédicas de Sevilla, IBIS/Universidad de Sevilla/Hospital Universitario Virgen del Rocío/Junta de Andalucía/CSIC, Seville 41013, Spain
| | - Karin Hochrainer
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York 10065
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2
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Bamford RA, Zuko A, Eve M, Sprengers JJ, Post H, Taggenbrock RLRE, Fäβler D, Mehr A, Jones OJR, Kudzinskas A, Gandawijaya J, Müller UC, Kas MJH, Burbach JPH, Oguro-Ando A. CNTN4 modulates neural elongation through interplay with APP. Open Biol 2024; 14:240018. [PMID: 38745463 PMCID: PMC11293442 DOI: 10.1098/rsob.240018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 05/16/2024] Open
Abstract
The neuronal cell adhesion molecule contactin-4 (CNTN4) is genetically associated with autism spectrum disorder (ASD) and other psychiatric disorders. Cntn4-deficient mouse models have previously shown that CNTN4 plays important roles in axon guidance and synaptic plasticity in the hippocampus. However, the pathogenesis and functional role of CNTN4 in the cortex has not yet been investigated. Our study found a reduction in cortical thickness in the motor cortex of Cntn4 -/- mice, but cortical cell migration and differentiation were unaffected. Significant morphological changes were observed in neurons in the M1 region of the motor cortex, indicating that CNTN4 is also involved in the morphology and spine density of neurons in the motor cortex. Furthermore, mass spectrometry analysis identified an interaction partner for CNTN4, confirming an interaction between CNTN4 and amyloid-precursor protein (APP). Knockout human cells for CNTN4 and/or APP revealed a relationship between CNTN4 and APP. This study demonstrates that CNTN4 contributes to cortical development and that binding and interplay with APP controls neural elongation. This is an important finding for understanding the physiological function of APP, a key protein for Alzheimer's disease. The binding between CNTN4 and APP, which is involved in neurodevelopment, is essential for healthy nerve outgrowth.
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Affiliation(s)
- Rosemary A. Bamford
- University of Exeter Medical School, University of Exeter, ExeterEX2 5DW, UK
| | - Amila Zuko
- Department of Molecular Neurobiology, Donders Institute for Brain, Cognition and Behaviour and Faculty of Science, Radboud University, Nijmegen, The Netherlands
| | - Madeline Eve
- University of Exeter Medical School, University of Exeter, ExeterEX2 5DW, UK
| | - Jan J. Sprengers
- Department of Translational Neuroscience, UMC Utrecht Brain Center, UMC Utrecht, Utrecht3508 AB, The Netherlands
| | - Harm Post
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht, Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
- Netherlands Proteomics Centre, Utrecht, The Netherlands
| | - Renske L. R. E. Taggenbrock
- Department of Translational Neuroscience, UMC Utrecht Brain Center, UMC Utrecht, Utrecht3508 AB, The Netherlands
| | - Dominique Fäβler
- Institute for Pharmacy and Molecular Biotechnology (IPMB), Functional Genomics, University of Heidelberg, Heidelberg69120, Germany
| | - Annika Mehr
- Institute for Pharmacy and Molecular Biotechnology (IPMB), Functional Genomics, University of Heidelberg, Heidelberg69120, Germany
| | - Owen J. R. Jones
- University of Exeter Medical School, University of Exeter, ExeterEX2 5DW, UK
| | - Aurimas Kudzinskas
- University of Exeter Medical School, University of Exeter, ExeterEX2 5DW, UK
| | - Josan Gandawijaya
- University of Exeter Medical School, University of Exeter, ExeterEX2 5DW, UK
| | - Ulrike C. Müller
- Institute for Pharmacy and Molecular Biotechnology (IPMB), Functional Genomics, University of Heidelberg, Heidelberg69120, Germany
| | - Martien J. H. Kas
- Department of Translational Neuroscience, UMC Utrecht Brain Center, UMC Utrecht, Utrecht3508 AB, The Netherlands
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - J. Peter H. Burbach
- Department of Translational Neuroscience, UMC Utrecht Brain Center, UMC Utrecht, Utrecht3508 AB, The Netherlands
| | - Asami Oguro-Ando
- University of Exeter Medical School, University of Exeter, ExeterEX2 5DW, UK
- Department of Pharmacy, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan
- Research Institute for Science and Technology, Tokyo University of Science, Tokyo, Japan
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3
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Li M, Cheng W, Zhang L, Zhou C, Peng X, Yu S, Zhang W. Novel Roles of RNA m6A Methylation Regulators in the Occurrence of Alzheimer’s Disease and the Subtype Classification. Int J Mol Sci 2022; 23:ijms231810766. [PMID: 36142676 PMCID: PMC9504232 DOI: 10.3390/ijms231810766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/09/2022] [Accepted: 09/10/2022] [Indexed: 11/16/2022] Open
Abstract
Alzheimer’s disease (AD) is one of the most common forms of dementia, closely related to epigenetic factors. N6-methyladenosine (m6A) is the most abundant RNA modification, affecting the pathogenesis and development of neurodegenerative diseases. This study was the first exploration of the combined role of 25 common m6A RNA methylation regulators in AD through the integrated bioinformatics approaches. The 14 m6A regulators related to AD were selected by analyzing differences between AD patients and normal controls. Based on the selected m6A regulators, AD patients could be well classified into two m6A models using consensus clustering. The two clusters of patients had different immune profiles, and m6A regulators were associated with the components of immune cells. Additionally, there were 19 key AD genes obtained by screening differential genes through weighted gene co-expression network and least absolute shrinkage and selection operator regression analysis, which were highly associated with important m6A regulators during the occurrence of AD. More interestingly, NOTCH2 and NME1 could be potential targets for m6A regulation of AD. Taken together, these findings indicate that dysregulation of m6A methylation affects the occurrence of AD and is vital for the subtype classification and immune infiltration of AD.
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Liu T, Zhang T, Nicolas M, Boussicault L, Rice H, Soldano A, Claeys A, Petrova I, Fradkin L, De Strooper B, Potier MC, Hassan BA. The amyloid precursor protein is a conserved Wnt receptor. eLife 2021; 10:69199. [PMID: 34515635 PMCID: PMC8437438 DOI: 10.7554/elife.69199] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 09/01/2021] [Indexed: 12/31/2022] Open
Abstract
The Amyloid Precursor Protein (APP) and its homologues are transmembrane proteins required for various aspects of neuronal development and activity, whose molecular function is unknown. Specifically, it is unclear whether APP acts as a receptor, and if so what its ligand(s) may be. We show that APP binds the Wnt ligands Wnt3a and Wnt5a and that this binding regulates APP protein levels. Wnt3a binding promotes full-length APP (flAPP) recycling and stability. In contrast, Wnt5a promotes APP targeting to lysosomal compartments and reduces flAPP levels. A conserved Cysteine-Rich Domain (CRD) in the extracellular portion of APP is required for Wnt binding, and deletion of the CRD abrogates the effects of Wnts on flAPP levels and trafficking. Finally, loss of APP results in increased axonal and reduced dendritic growth of mouse embryonic primary cortical neurons. This phenotype can be cell-autonomously rescued by full length, but not CRD-deleted, APP and regulated by Wnt ligands in a CRD-dependent manner.
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Affiliation(s)
- Tengyuan Liu
- Paris Brain Institute - Institut du Cerveau, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, Paris, France.,Doctoral School of Biomedical Sciences, Leuven, Belgium
| | - Tingting Zhang
- Paris Brain Institute - Institut du Cerveau, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, Paris, France.,Doctoral School of Biomedical Sciences, Leuven, Belgium
| | - Maya Nicolas
- Doctoral School of Biomedical Sciences, Leuven, Belgium.,Center for Brain and Disease, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Lydie Boussicault
- Paris Brain Institute - Institut du Cerveau, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, Paris, France
| | - Heather Rice
- Center for Brain and Disease, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Alessia Soldano
- Center for Brain and Disease, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Annelies Claeys
- Center for Brain and Disease, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Iveta Petrova
- Laboratory of Developmental Neurobiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Lee Fradkin
- Laboratory of Developmental Neurobiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Bart De Strooper
- Center for Brain and Disease, Leuven, Belgium.,UK Dementia Research institute at University College London, London, United Kingdom
| | - Marie-Claude Potier
- Paris Brain Institute - Institut du Cerveau, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, Paris, France
| | - Bassem A Hassan
- Paris Brain Institute - Institut du Cerveau, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, Paris, France
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5
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Langness VF, van der Kant R, Das U, Wang L, Chaves RDS, Goldstein LSB. Cholesterol-lowering drugs reduce APP processing to Aβ by inducing APP dimerization. Mol Biol Cell 2020; 32:247-259. [PMID: 33296223 PMCID: PMC8098827 DOI: 10.1091/mbc.e20-05-0345] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Amyloid beta (Aβ) is a major component of amyloid plaques, which are a key pathological hallmark found in the brains of Alzheimer’s disease (AD) patients. We show that statins are effective at reducing Aβ in human neurons from nondemented control subjects, as well as subjects with familial AD and sporadic AD. Aβ is derived from amyloid precursor protein (APP) through sequential proteolytic cleavage by BACE1 and γ-secretase. While previous studies have shown that cholesterol metabolism regulates APP processing to Aβ, the mechanism is not well understood. We used iPSC-derived neurons and bimolecular fluorescence complementation assays in transfected cells to elucidate how altering cholesterol metabolism influences APP processing. Altering cholesterol metabolism using statins decreased the generation of sAPPβ and increased levels of full-length APP (flAPP), indicative of reduced processing of APP by BACE1. We further show that statins decrease flAPP interaction with BACE1 and enhance APP dimerization. Additionally, statin-induced changes in APP dimerization and APP-BACE1 are dependent on cholesterol binding to APP. Our data indicate that statins reduce Aβ production by decreasing BACE1 interaction with flAPP and suggest that this process may be regulated through competition between APP dimerization and APP cholesterol binding.
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Affiliation(s)
- Vanessa F Langness
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093.,Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92037
| | - Rik van der Kant
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam de Boelelaan 1087, 1081 HV Amsterdam, The Netherlands.,Alzheimer Center Amsterdam, Department of Neurology, Amsterdam Neuroscience, Amsterdam UMC, De Boelelaan 1118, 1081 HZ Amsterdam, The Netherlands
| | - Utpal Das
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093.,Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92037
| | - Louie Wang
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093.,Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92037
| | - Rodrigo Dos Santos Chaves
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093.,Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92037
| | - Lawrence S B Goldstein
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093.,Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093.,Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92037
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6
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Salazar JL, Yang SA, Yamamoto S. Post-Developmental Roles of Notch Signaling in the Nervous System. Biomolecules 2020; 10:biom10070985. [PMID: 32630239 PMCID: PMC7408554 DOI: 10.3390/biom10070985] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 12/14/2022] Open
Abstract
Since its discovery in Drosophila, the Notch signaling pathway has been studied in numerous developmental contexts in diverse multicellular organisms. The role of Notch signaling in nervous system development has been extensively investigated by numerous scientists, partially because many of the core Notch signaling components were initially identified through their dramatic ‘neurogenic’ phenotype of developing fruit fly embryos. Components of the Notch signaling pathway continue to be expressed in mature neurons and glia cells, which is suggestive of a role in the post-developmental nervous system. The Notch pathway has been, so far, implicated in learning and memory, social behavior, addiction, and other complex behaviors using genetic model organisms including Drosophila and mice. Additionally, Notch signaling has been shown to play a modulatory role in several neurodegenerative disease model animals and in mediating neural toxicity of several environmental factors. In this paper, we summarize the knowledge pertaining to the post-developmental roles of Notch signaling in the nervous system with a focus on discoveries made using the fruit fly as a model system as well as relevant studies in C elegans, mouse, rat, and cellular models. Since components of this pathway have been implicated in the pathogenesis of numerous psychiatric and neurodegenerative disorders in human, understanding the role of Notch signaling in the mature brain using model organisms will likely provide novel insights into the mechanisms underlying these diseases.
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Affiliation(s)
- Jose L. Salazar
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; (J.L.S.); (S.-A.Y.)
| | - Sheng-An Yang
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; (J.L.S.); (S.-A.Y.)
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; (J.L.S.); (S.-A.Y.)
- Department of Neuroscience, BCM, Houston, TX 77030, USA
- Program in Developmental Biology, BCM, Houston, TX 77030, USA
- Development, Disease Models & Therapeutics Graduate Program, BCM, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030, USA
- Correspondence: ; Tel.: +1-832-824-8119
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7
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Ho DM, Artavanis-Tsakonas S, Louvi A. The Notch pathway in CNS homeostasis and neurodegeneration. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2019; 9:e358. [PMID: 31502763 DOI: 10.1002/wdev.358] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/19/2019] [Accepted: 06/23/2019] [Indexed: 12/19/2022]
Abstract
The role of the Notch signaling pathway in neural development has been well established over many years. More recent studies, however, have demonstrated that Notch continues to be expressed and active throughout adulthood in many areas of the central nervous system. Notch signals have been implicated in adult neurogenesis, memory formation, and synaptic plasticity in the adult organism, as well as linked to acute brain trauma and chronic neurodegenerative conditions. NOTCH3 mutations are responsible for the most common form of hereditary stroke, the progressive disorder cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Notch has also been associated with several progressive neurodegenerative diseases, including Alzheimer's disease, multiple sclerosis, and amyotrophic lateral sclerosis. Although numerous studies link Notch activity with CNS homeostasis and neurodegenerative diseases, the data thus far are primarily correlative, rather than functional. Nevertheless, the evidence for Notch pathway activity in specific neural cellular contexts is strong, and certainly intriguing, and points to the possibility that the pathway carries therapeutic promise. This article is categorized under: Nervous System Development > Flies Signaling Pathways > Cell Fate Signaling Nervous System Development > Vertebrates: General Principles.
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Affiliation(s)
- Diana M Ho
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
| | | | - Angeliki Louvi
- Departments of Neurosurgery and Neuroscience and Program on Neurogenetics, Yale School of Medicine, New Haven, Connecticut
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8
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Sheng H, Hu Y, Zhou Y, Fan S, Cao Y, Zhao X, Yang W. A hydroxyphenylquinazolinone-based fluorescent probe for turn-on detection of cysteine with a large Stokes shift and its application in living cells. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2018.07.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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9
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Liang JW, Fang ZY, Huang Y, Liuyang ZY, Zhang XL, Wang JL, Wei H, Wang JZ, Wang XC, Zeng J, Liu R. Application of Weighted Gene Co-Expression Network Analysis to Explore the Key Genes in Alzheimer's Disease. J Alzheimers Dis 2018; 65:1353-1364. [PMID: 30124448 PMCID: PMC6218130 DOI: 10.3233/jad-180400] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2018] [Indexed: 12/16/2022]
Abstract
BACKGROUND Weighted co-expression network analysis (WGCNA) is a powerful systems biology method to describe the correlation of gene expression based on the microarray database, which can be used to facilitate the discovery of therapeutic targets or candidate biomarkers in diseases. OBJECTIVE To explore the key genes in the development of Alzheimer's disease (AD) by using WGCNA. METHODS The whole gene expression data GSE1297 from AD and control human hippocampus was obtained from the GEO database in NCBI. Co-expressed genes were clustered into different modules. Modules of interest were identified through calculating the correlation coefficient between the module and phenotypic traits. GO and pathway enrichment analyses were conducted, and the central players (key hub genes) within the modules of interest were identified through network analysis. The expression of the identified key genes was confirmed in AD transgenic mice through using qRT-PCR. RESULTS Two modules were found to be associated with AD clinical severity, which functioning mainly in mineral absorption, NF-κB signaling, and cGMP-PKG signaling pathways. Through analysis of the two modules, we found that metallothionein (MT), Notch2, MSX1, ADD3, and RAB31 were highly correlated with AD phenotype. Increase in expression of these genes was confirmed in aged AD transgenic mice. CONCLUSION WGCNA analysis can be used to analyze and predict the key genes in AD. MT1, MT2, MSX1, NOTCH2, ADD3, and RAB31 are identified to be the most relevant genes, which may be potential targets for AD therapy.
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Affiliation(s)
- Jia-Wei Liang
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zheng-Yu Fang
- Department of Rehabilitation Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yong Huang
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhen-yu Liuyang
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao-Lin Zhang
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing-Lin Wang
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hui Wei
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jian-Zhi Wang
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao-Chuan Wang
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ji Zeng
- Department of Clinic Laboratory, Pu Ai Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Rong Liu
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
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10
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Alfred V, Vaccari T. Mechanisms of Non-canonical Signaling in Health and Disease: Diversity to Take Therapy up a Notch? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1066:187-204. [PMID: 30030827 DOI: 10.1007/978-3-319-89512-3_9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Non-canonical Notch signaling encompasses a wide range of cellular processes, diverging considerably from the established paradigm. It can dispense of ligand, proteolytic or nuclear activity. Non-canonical Notch signaling events have been studied mostly in the fruit fly Drosophila melanogaster, the organism in which Notch was identified first and a powerful model for understanding signaling outcomes. However, non-canonical events are ill-defined and their involvement in human physiology is not clear, hampering our understanding of diseases arising from Notch signaling alterations. At a time in which therapies based on specific targeting of Notch signaling are still an unfulfilled promise, detailed understanding of non-canonical Notch events might be key to devising more specific and less toxic pharmacologic options. Based on the blueprint of non-canonical signaling in Drosophila, here, we review and rationalize current evidence about non-canonical Notch signaling. Our effort might inform Notch biologists developing new research avenues and clinicians seeking future treatment of Notch-dependent diseases.
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Affiliation(s)
- Victor Alfred
- IFOM, Istituto FIRC di Oncologia Molecolare at IFOM-IEO Campus, Milan, Italy
| | - Thomas Vaccari
- IFOM, Istituto FIRC di Oncologia Molecolare at IFOM-IEO Campus, Milan, Italy.
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy.
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11
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Abstract
Notch signaling is evolutionarily conserved from Drosophila to human. It plays critical roles in neural stem cell maintenance and neurogenesis in the embryonic brain as well as in the adult brain. Notch functions greatly depend on careful regulation and cross-talk with other regulatory mechanisms. Deregulation of Notch signaling is involved in many neurodegenerative diseases and brain disorders. Here, we summarize the fundamental role of Notch in neuronal development and specification and discuss how epigenetic regulation and pathway cross-talk contribute to Notch function. In addition, we cover aberrant alterations of Notch signaling in the diseased brain. The aim of this review is to provide an insight into how Notch signaling works in different contexts to control neurogenesis and its potential effects in diagnoses and therapies of neurodegeneration, brain tumors and disorders.
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Affiliation(s)
- Runrui Zhang
- Embryology and Stem Cell Biology, Department of Biomedicine, University of Basel, Mattenstrasse 28, 4058, Basel, Switzerland
| | - Anna Engler
- Embryology and Stem Cell Biology, Department of Biomedicine, University of Basel, Mattenstrasse 28, 4058, Basel, Switzerland
| | - Verdon Taylor
- Embryology and Stem Cell Biology, Department of Biomedicine, University of Basel, Mattenstrasse 28, 4058, Basel, Switzerland.
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12
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Guénette S, Strecker P, Kins S. APP Protein Family Signaling at the Synapse: Insights from Intracellular APP-Binding Proteins. Front Mol Neurosci 2017; 10:87. [PMID: 28424586 PMCID: PMC5371672 DOI: 10.3389/fnmol.2017.00087] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 03/13/2017] [Indexed: 12/17/2022] Open
Abstract
Understanding the molecular mechanisms underlying amyloid precursor protein family (APP/APP-like proteins, APLP) function in the nervous system can be achieved by studying the APP/APLP interactome. In this review article, we focused on intracellular APP interacting proteins that bind the YENPTY internalization motif located in the last 15 amino acids of the C-terminal region. These proteins, which include X11/Munc-18-interacting proteins (Mints) and FE65/FE65Ls, represent APP cytosolic binding partners exhibiting different neuronal functions. A comparison of FE65 and APP family member mutant mice revealed a shared function for APP/FE65 protein family members in neurogenesis and neuronal positioning. Accumulating evidence also supports a role for membrane-associated APP/APLP proteins in synapse formation and function. Therefore, it is tempting to speculate that APP/APLP C-terminal interacting proteins transmit APP/APLP-dependent signals at the synapse. Herein, we compare our current knowledge of the synaptic phenotypes of APP/APLP mutant mice with those of mice lacking different APP/APLP interaction partners and discuss the possible downstream effects of APP-dependent FE65/FE65L or X11/Mint signaling on synaptic vesicle release, synaptic morphology and function. Given that the role of X11/Mint proteins at the synapse is well-established, we propose a model highlighting the role of FE65 protein family members for transduction of APP/APLP physiological function at the synapse.
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Affiliation(s)
| | - Paul Strecker
- Department of Biology, Division of Human Biology, University of KaiserslauternKaiserslautern, Germany
| | - Stefan Kins
- Department of Biology, Division of Human Biology, University of KaiserslauternKaiserslautern, Germany
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Canu N, Pagano I, La Rosa LR, Pellegrino M, Ciotti MT, Mercanti D, Moretti F, Sposato V, Triaca V, Petrella C, Maruyama IN, Levi A, Calissano P. Association of TrkA and APP Is Promoted by NGF and Reduced by Cell Death-Promoting Agents. Front Mol Neurosci 2017; 10:15. [PMID: 28197073 PMCID: PMC5281621 DOI: 10.3389/fnmol.2017.00015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 01/11/2017] [Indexed: 12/31/2022] Open
Abstract
The amyloid precursor protein (APP) interacts with the tropomyosin receptor kinase A (TrkA) in normal rat, mouse, and human brain tissue but not in Alzheimer's disease (AD) brain tissue. However, it has not been reported whether the two proteins interact directly, and if so, which domains are involved. Clarifying these points will increase our understanding of the role and regulation of the TrkA/APP interaction in normal brain functioning as well as in AD. Here we addressed these questions using bimolecular fluorescence complementation (BiFC) and the proximity ligation assay (PLA). We demonstrated that exogenously expressed APP and TrkA associate through their juxtamembrane/transmembrane domains, to form a complex that localizes mainly to the plasma membrane, endoplasmic reticulum (ER) and Golgi. Formation of the complex was inhibited by p75NTR, ShcC and Mint-2. Importantly, we demonstrated that the association between endogenous APP and TrkA in primary septal neurons were modified by NGF, or by drugs that either inhibit ER-to-Golgi transport or perturb microtubules and microfilaments. Interestingly, several agents that induce cell death [amyloid β (Aβ)-peptide, staurosporine and rapamycin], albeit via different mechanisms, all caused dissociation of APP/TrkA complexes and increased production of C-terminal fragment (β-CTF) APP fragment. These findings open new perspectives for investigating the interplay between these proteins during neurodegeneration and AD.
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Affiliation(s)
- Nadia Canu
- Department of System Medicine, University of Rome "Tor Vergata"Rome, Italy; Institute of Cellular Biology and Neurobiology, National Council of Research of RomeRome, Italy
| | - Ilaria Pagano
- Institute of Cellular Biology and Neurobiology, National Council of Research of Rome Rome, Italy
| | - Luca Rosario La Rosa
- Institute of Cellular Biology and Neurobiology, National Council of Research of Rome Rome, Italy
| | - Marsha Pellegrino
- Institute of Cellular Biology and Neurobiology, National Council of Research of Rome Rome, Italy
| | - Maria Teresa Ciotti
- Institute of Cellular Biology and Neurobiology, National Council of Research of Rome Rome, Italy
| | - Delio Mercanti
- Institute of Cellular Biology and Neurobiology, National Council of Research of Rome Rome, Italy
| | - Fabiola Moretti
- Institute of Cellular Biology and Neurobiology, National Council of Research of Rome Rome, Italy
| | - Valentina Sposato
- Institute of Cellular Biology and Neurobiology, National Council of Research of RomeRome, Italy; European Brain Research InstituteRome, Italy
| | - Viviana Triaca
- Institute of Cellular Biology and Neurobiology, National Council of Research of RomeRome, Italy; European Brain Research InstituteRome, Italy
| | - Carla Petrella
- Institute of Cellular Biology and Neurobiology, National Council of Research of Rome Rome, Italy
| | - Ichiro N Maruyama
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University Okinawa, Japan
| | - Andrea Levi
- Institute of Cellular Biology and Neurobiology, National Council of Research of Rome Rome, Italy
| | - Pietro Calissano
- European Brain Research InstituteRome, Italy; Institute of Cellular Biology and Neurobiology, National Council of Research of RomeRome, Italy
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β-Amyloid precursor protein-b is essential for Mauthner cell development in the zebrafish in a Notch-dependent manner. Dev Biol 2016; 413:26-38. [PMID: 26994945 DOI: 10.1016/j.ydbio.2016.03.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 03/10/2016] [Indexed: 02/05/2023]
Abstract
Amyloid precursor protein (APP) is a transmembrane glycoprotein that has been the subject of intense research because of its implication in Alzheimer's disease. However, the physiological function of APP in the development and maintenance of the central nervous system remains largely unknown. We have previously shown that the APP homologue in zebrafish (Danio rerio), Appb, is required for motor neuron patterning and formation. Here we study the function of Appb during neurogenesis in the zebrafish hindbrain. Partial knockdown of Appb using antisense morpholino oligonucleotides blocked the formation of the Mauthner neurons, uni- or bilaterally, with an aberrant behavior as a consequence of this cellular change. The Appb morphants had decreased neurogenesis, increased notch signaling and notch1a expression at the expense of deltaA/D expression. The Mauthner cell development could be restored either by a general decrease in Notch signaling through γ-secretase inhibition or by a partial knock down of Notch1a. Together, this demonstrates the importance of Appb in neurogenesis and for the first time shows the essential requirement of Appb in the formation of a specific cell type, the Mauthner cell, in the hindbrain during development. Our results suggest that Appb-regulated neurogenesis is mediated through balancing the Notch1a signaling pathway and provide new insights into the development of the Mauthner cell.
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Stanga S, Zanou N, Audouard E, Tasiaux B, Contino S, Vandermeulen G, René F, Loeffler JP, Clotman F, Gailly P, Dewachter I, Octave JN, Kienlen-Campard P. APP-dependent glial cell line-derived neurotrophic factor gene expression drives neuromuscular junction formation. FASEB J 2015; 30:1696-711. [PMID: 26718890 DOI: 10.1096/fj.15-278739] [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] [Received: 07/09/2015] [Accepted: 12/08/2015] [Indexed: 12/13/2022]
Abstract
Besides its crucial role in the pathogenesis of Alzheimer's disease, the knowledge of amyloid precursor protein (APP) physiologic functions remains surprisingly scarce. Here, we show that APP regulates the transcription of the glial cell line-derived neurotrophic factor (GDNF). APP-dependent regulation of GDNF expression affects muscle strength, muscular trophy, and both neuronal and muscular differentiation fundamental for neuromuscular junction (NMJ) maturation in vivo In a nerve-muscle coculture model set up to modelize NMJ formation in vitro, silencing of muscular APP induces a 30% decrease in secreted GDNF levels and a 40% decrease in the total number of NMJs together with a significant reduction in the density of acetylcholine vesicles at the presynaptic site and in neuronal maturation. These defects are rescued by GDNF expression in muscle cells in the conditions where muscular APP has been previously silenced. Expression of GDNF in muscles of amyloid precursor protein null mice corrected the aberrant synaptic morphology of NMJs. Our findings highlight for the first time that APP-dependent GDNF expression drives the process of NMJ formation, providing new insights into the link between APP gene regulatory network and physiologic functions.-Stanga, S., Zanou, N., Audouard, E., Tasiaux, B., Contino, S., Vandermeulen, G., René, F., Loeffler, J.-P., Clotman, F., Gailly, P., Dewachter, I., Octave, J.-N., Kienlen-Campard, P. APP-dependent glial cell line-derived neurotrophic factor gene expression drives neuromuscular junction formation.
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Affiliation(s)
- Serena Stanga
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Nadège Zanou
- Laboratory of Cell Physiology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Emilie Audouard
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Bernadette Tasiaux
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Sabrina Contino
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Gaëlle Vandermeulen
- Advanced Drug Delivery and Biomaterials, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium; and
| | - Frédérique René
- Institut National de la Santé et de la Recherche Médicale, Unité 1118 Mécanismes Centraux et Périphériques de la Neurodégénérescence, Université de Strasbourg, Strasbourg Cedex, France
| | - Jean-Philippe Loeffler
- Institut National de la Santé et de la Recherche Médicale, Unité 1118 Mécanismes Centraux et Périphériques de la Neurodégénérescence, Université de Strasbourg, Strasbourg Cedex, France
| | - Frédéric Clotman
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Philippe Gailly
- Laboratory of Cell Physiology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Ilse Dewachter
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Jean-Noël Octave
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Pascal Kienlen-Campard
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium;
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Decock M, El Haylani L, Stanga S, Dewachter I, Octave JN, Smith SO, Constantinescu SN, Kienlen-Campard P. Analysis by a highly sensitive split luciferase assay of the regions involved in APP dimerization and its impact on processing. FEBS Open Bio 2015; 5:763-73. [PMID: 26500837 PMCID: PMC4588712 DOI: 10.1016/j.fob.2015.09.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 08/07/2015] [Accepted: 09/01/2015] [Indexed: 12/27/2022] Open
Abstract
Amyloid precursor protein (APP) dimerizes more than its C-terminal fragments in cells. Mutations of membrane GXXXG motifs affect Aβ production but not APP dimerization. Deletion of the APP intracellular domain increases APP dimerization.
Alzheimer’s disease (AD) is a neurodegenerative disease that causes progressive loss of cognitive functions, leading to dementia. Two types of lesions are found in AD brains: neurofibrillary tangles and senile plaques. The latter are composed mainly of the β-amyloid peptide (Aβ) generated by amyloidogenic processing of the amyloid precursor protein (APP). Several studies have suggested that dimerization of APP is closely linked to Aβ production. Nevertheless, the mechanisms controlling APP dimerization and their role in APP function are not known. Here we used a new luciferase complementation assay to analyze APP dimerization and unravel the involvement of its three major domains: the ectodomain, the transmembrane domain and the intracellular domain. Our results indicate that within cells full-length APP dimerizes more than its α and β C-terminal fragments, confirming the pivotal role of the ectodomain in this process. Dimerization of the APP transmembrane (TM) domain has been reported to regulate processing at the γ-cleavage site. We show that both non-familial and familial AD mutations in the TM GXXXG motifs strongly modulate Aβ production, but do not consistently change dimerization of the C-terminal fragments. Finally, we found for the first time that removal of intracellular domain strongly increases APP dimerization. Increased APP dimerization is linked to increased non-amyloidogenic processing.
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Key Words
- AD, Alzheimer’s disease
- AICD, APP intracellular domain
- APP
- APP, amyloid precursor protein
- Alzheimer disease
- Amyloid beta peptide
- Aβ, β-amyloid peptide
- CHO, chinese hamster ovary
- CTF, C-terminal fragment
- DAPT, N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester
- DTT, dithiothreitol
- Dimerization
- ECL, enzymatic chemi-luminescence
- ECLIA, electro-chemiluminescence immuno-assay
- FBS, fetal bovine serum
- FRET, fluorescence resonance energy transfer
- GXXXG motifs
- KPI, Kunitz-type protease inhibitor
- NSAIDs, nonsteroidal anti-inflammatory drugs
- PBS, phosphate buffered saline
- PS1/PS2, presenilin1/presenilin2
- RLU, relative light unit
- SP, signal peptide
- Split luciferase
- TM, transmembrane
- YFP, yellow fluorescent protein
- sAPPα, soluble APPα
- sAPPβ, soluble APPβ
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Affiliation(s)
- Marie Decock
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Laetitia El Haylani
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Serena Stanga
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Ilse Dewachter
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Jean-Noël Octave
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Steven O Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Stefan N Constantinescu
- de Duve Institute and Ludwig Institute for Cancer Research, Université catholique de Louvain, Brussels 1200, Belgium
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Bram Y, Lampel A, Shaltiel-Karyo R, Ezer A, Scherzer-Attali R, Segal D, Gazit E. Monitoring and Targeting the Initial Dimerization Stage of Amyloid Self-Assembly. Angew Chem Int Ed Engl 2014; 54:2062-7. [DOI: 10.1002/anie.201408744] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 11/03/2014] [Indexed: 11/11/2022]
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18
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Bram Y, Lampel A, Shaltiel-Karyo R, Ezer A, Scherzer-Attali R, Segal D, Gazit E. Monitoring and Targeting the Initial Dimerization Stage of Amyloid Self-Assembly. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201408744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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Lim S, Haque MM, Kim D, Kim DJ, Kim YK. Cell-based Models To Investigate Tau Aggregation. Comput Struct Biotechnol J 2014; 12:7-13. [PMID: 25505502 PMCID: PMC4262059 DOI: 10.1016/j.csbj.2014.09.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 09/20/2014] [Accepted: 09/24/2014] [Indexed: 12/14/2022] Open
Abstract
Accumulation of abnormal tau aggregates in neuron is an important pathological signature in multiple neurodegenerative disorders including Alzheimer's disease. Tau is a neuron specific microtubule-associated protein that regulates microtubule stability, which is critical for axonal outgrowth and synaptic plasticity. In a pathological condition, tau dissociates from microtubules and forms insoluble aggregates called neurofibrillary tangles (NFTs). The accumulation of NFTs in neuron directly correlates with microtubule dysfunction and neuronal degeneration. Due to the pathophysiological importance of tau, great efforts have been made to understand tau aggregation processes and find therapeutics to halt or reverse the processes. However, progress has been slow due to the lack of a suitable method for monitoring tau aggregation. In this mini-review, we will review the conventional methods for studying tau aggregation, and introduce recent cell-based sensor approaches that allow monitoring tau aggregation in living cells.
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Affiliation(s)
- Sungsu Lim
- Center for Neuro-medicine, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 136-791, Republic of Korea
| | - Md Mamunul Haque
- Center for Neuro-medicine, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 136-791, Republic of Korea ; Biological Chemistry, University of Science and Technology, Daejon 305-333, Republic of Korea
| | - Dohee Kim
- Center for Neuro-medicine, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 136-791, Republic of Korea ; Department of Biotechnology, Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Dong Jin Kim
- Center for Neuro-medicine, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 136-791, Republic of Korea
| | - Yun Kyung Kim
- Center for Neuro-medicine, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 136-791, Republic of Korea
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20
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Lasry I, Golan Y, Berman B, Amram N, Glaser F, Assaraf YG. In situ dimerization of multiple wild type and mutant zinc transporters in live cells using bimolecular fluorescence complementation. J Biol Chem 2014; 289:7275-92. [PMID: 24451381 DOI: 10.1074/jbc.m113.533786] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Zinc transporters (ZnTs) facilitate zinc efflux and zinc compartmentalization, thereby playing a key role in multiple physiological processes and pathological disorders, presumed to be modulated by transporter dimerization. We recently proposed that ZnT2 homodimerization is the underlying basis for the dominant negative effect of a novel heterozygous G87R mutation identified in women producing zinc-deficient milk. To provide direct visual evidence for the in situ dimerization and function of multiple normal and mutant ZnTs, we applied here the bimolecular fluorescence complementation (BiFC) technique, which enables direct visualization of specific protein-protein interactions. BiFC is based upon reconstitution of an intact fluorescent protein including YFP when its two complementary, non-fluorescent N- and C-terminal fragments (termed YN and YC) are brought together by a pair of specifically interacting proteins. Homodimerization of ZnT1, -2, -3, -4, and -7 was revealed by high subcellular fluorescence observed upon co-transfection of non-fluorescent ZnT-YC and ZnT-YN; this homodimer fluorescence localized in the characteristic compartments of each ZnT. The validity of the BiFC assay in ZnT dimerization was further corroborated when high fluorescence was obtained upon co-transfection of ZnT5-YC and ZnT6-YN, which are known to form heterodimers. We further show that BiFC recapitulated the pathogenic role that ZnT mutations play in transient neonatal zinc deficiency. Zinquin, a fluorescent zinc probe applied along with BiFC, revealed the in situ functionality of ZnT dimers. Hence, the current BiFC-Zinquin technique provides the first in situ evidence for the dimerization and function of wild type and mutant ZnTs in live cells.
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Affiliation(s)
- Inbal Lasry
- From the Fred Wyszkowski Cancer Research Laboratory, Department of Biology, and
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Notch-inducible hyperphosphorylated CREB and its ultradian oscillation in long-term memory formation. J Neurosci 2013; 33:12825-34. [PMID: 23904617 DOI: 10.1523/jneurosci.0783-13.2013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Notch is a cell surface receptor that is known to regulate developmental processes by establishing physical contact between neighboring cells. Many recent studies show that it also plays an important role in the formation of long-term memory (LTM) in adults, implying that memory formation requires regulation at the level of cell-cell contacts among brain cells. Neither the target of Notch activity in LTM formation nor the underlying mechanism of regulation is known. We report here results of our studies in adult Drosophila melanogaster showing that Notch regulates dCrebB-17A, the CREB protein. CREB is a transcriptional factor that is pivotal for intrinsic and synaptic plasticity involved in LTM formation. Notch in conjunction with PKC activity upregulates the level of a hyperphosphorylated form of CREB (hyper-PO4 CREB) and triggers its ultradian oscillation, both of which are linked to LTM formation. One of the sites that is phosphorylated in hyper-PO4 CREB is serine 231, which is the functional equivalent of mammalian CREB serine 133, the phosphorylation of which is an important regulator of CREB functions. Our data suggest the model that Notch and PKC activities generate a cyclical accumulation of cytoplasmic hyper-PO4 CREB that is a precursor for generating the nuclear CREB isoforms. Cyclical accumulation of CREB might be important for repetitive aspects of LTM formation, such as memory consolidation. Because Notch, PKC, and CREB have been implicated in many neurodegenerative diseases (e.g., Alzheimer's disease), our data might also shed some light on memory loss and dementia.
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Visualization and quantification of APP intracellular domain-mediated nuclear signaling by bimolecular fluorescence complementation. PLoS One 2013; 8:e76094. [PMID: 24086696 PMCID: PMC3783399 DOI: 10.1371/journal.pone.0076094] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 08/21/2013] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The amyloid precursor protein (APP) intracellular domain (AICD) is released from full-length APP upon sequential cleavage by either α- or β-secretase followed by γ-secretase. Together with the adaptor protein Fe65 and the histone acetyltransferase Tip60, AICD forms nuclear multiprotein complexes (AFT complexes) that function in transcriptional regulation. OBJECTIVE To develop a medium-throughput machine-based assay for visualization and quantification of AFT complex formation in cultured cells. METHODS We used cotransfection of bimolecular fluorescence complementation (BiFC) fusion constructs of APP and Tip60 for analysis of subcellular localization by confocal microscopy and quantification by flow cytometry (FC). RESULTS Our novel BiFC-constructs show a nuclear localization of AFT complexes that is identical to conventional fluorescence-tagged constructs. Production of the BiFC signal is dependent on the adaptor protein Fe65 resulting in fluorescence complementation only after Fe65-mediated nuclear translocation of AICD and interaction with Tip60. We applied the AFT-BiFC system to show that the Swedish APP familial Alzheimer's disease mutation increases AFT complex formation, consistent with the notion that AICD mediated nuclear signaling mainly occurs following APP processing through the amyloidogenic β-secretase pathway. Next, we studied the impact of posttranslational modifications of AICD on AFT complex formation. Mutation of tyrosine 682 in the YENPTY motif of AICD to phenylalanine prevents phosphorylation resulting in increased nuclear AFT-BiFC signals. This is consistent with the negative impact of tyrosine phosphorylation on Fe65 binding to AICD. Finally, we studied the effect of oxidative stress. Our data shows that oxidative stress, at a level that also causes cell death, leads to a reduction in AFT-BiFC signals. CONCLUSION We established a new method for visualization and FC quantification of the interaction between AICD, Fe65 and Tip60 in the nucleus based on BiFC. It enables flow cytometric analysis of AICD nuclear signaling and is characterized by scalability and low background fluorescence.
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Jiang W, Zhang Y, Meng F, Lian B, Chen X, Yu X, Dai E, Wang S, Liu X, Li X, Wang L, Li X. Identification of active transcription factor and miRNA regulatory pathways in Alzheimer’s disease. Bioinformatics 2013; 29:2596-602. [DOI: 10.1093/bioinformatics/btt423] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Cross-linking of cell surface amyloid precursor protein leads to increased β-amyloid peptide production in hippocampal neurons: implications for Alzheimer's disease. J Neurosci 2012; 32:10674-85. [PMID: 22855816 DOI: 10.1523/jneurosci.6473-11.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The accumulation of the β-amyloid peptide (Aβ) in Alzheimer's disease (AD) is thought to play a causative role in triggering synaptic dysfunction in neurons, leading to their eventual demise through apoptosis. Aβ is produced and secreted upon sequential cleavage of the amyloid precursor protein (APP) by β-secretases and γ-secretases. However, while Aβ levels have been shown to be increased in the brains of AD patients, little is known about how the cleavage of APP and the subsequent generation of Aβ is influenced, or whether the cleavage process changes over time. It has been proposed that Aβ can bind APP and promote amyloidogenic processing of APP, further enhancing Aβ production. Proof of this idea has remained elusive because a clear mechanism has not been identified, and the promiscuous nature of Aβ binding complicates the task of demonstrating the idea. To work around these problems, we used an antibody-mediated approach to bind and cross-link cell-surface APP in cultured rat primary hippocampal neurons. Here we show that cross-linking of APP is sufficient to raise the levels of Aβ in viable neurons with a concomitant increase in the levels of the β-secretase BACE1. This appears to occur as a result of a sorting defect that stems from the caspase-3-mediated inactivation of a key sorting adaptor protein, namely GGA3, which prevents the lysosomal degradation of BACE1. Together, our data suggest the occurrence of a positive pathogenic feedback loop involving Aβ and APP in affected neurons possibly allowing Aβ to spread to nearby healthy neurons.
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Ntelios D, Berninger B, Tzimagiorgis G. Numb and Alzheimer's disease: the current picture. Front Neurosci 2012; 6:145. [PMID: 23060745 PMCID: PMC3463830 DOI: 10.3389/fnins.2012.00145] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 09/14/2012] [Indexed: 11/23/2022] Open
Abstract
Twenty-three years ago, numb was identified as a critical regulator in Drosophila sensory organ precursor cell asymmetric divisions. Beyond the recently recognized role in carcinogenesis, Numb seems to be important in Alzheimer’s disease. This assertion comes from the involvement in various processes such as synapse morphogenesis, amyloid precursor protein trafficking, notch signaling, and neurogenesis. The purpose of the present mini-review is to provide the current picture of Numb’s participation in mechanisms underlying Alzheimer’s disease pathogenesis and emphasize potential aspects for future research.
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Affiliation(s)
- Dimitrios Ntelios
- Laboratory of Biological Chemistry, Medical School, Aristotle University of Thessaloniki Thessaloniki, Greece
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26
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Libeu CAP, Descamps O, Zhang Q, John V, Bredesen DE. Altering APP proteolysis: increasing sAPPalpha production by targeting dimerization of the APP ectodomain. PLoS One 2012; 7:e40027. [PMID: 22768208 PMCID: PMC3386930 DOI: 10.1371/journal.pone.0040027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 06/04/2012] [Indexed: 12/13/2022] Open
Abstract
One of the events associated with Alzheimer's disease is the dysregulation of α- versus β-cleavage of the amyloid precursor protein (APP). The product of α-cleavage (sAPPα) has neuroprotective properties, while Aβ1-42 peptide, a product of β-cleavage, is neurotoxic. Dimerization of APP has been shown to influence the relative rate of α- and β- cleavage of APP. Thus finding compounds that interfere with dimerization of the APP ectodomain and increase the α-cleavage of APP could lead to the development of new therapies for Alzheimer's disease. Examining the intrinsic fluorescence of a fragment of the ectodomain of APP, which dimerizes through the E2 and Aβ-cognate domains, revealed significant changes in the fluorescence of the fragment upon binding of Aβ oligomers--which bind to dimers of the ectodomain--and Aβ fragments--which destabilize dimers of the ectodomain. This technique was extended to show that RERMS-containing peptides (APP(695) 328-332), disulfiram, and sulfiram also inhibit dimerization of the ectodomain fragment. This activity was confirmed with small angle x-ray scattering. Analysis of the activity of disulfiram and sulfiram in an AlphaLISA assay indicated that both compounds significantly enhance the production of sAPPα by 7W-CHO and B103 neuroblastoma cells. These observations demonstrate that there is a class of compounds that modulates the conformation of the APP ectodomain and influences the ratio of α- to β-cleavage of APP. These compounds provide a rationale for the development of a new class of therapeutics for Alzheimer's disease.
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Affiliation(s)
- Clare A Peters Libeu
- Buck Institute for Research on Aging, Novato, California, United States of America.
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27
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Ben Khalifa N, Tyteca D, Courtoy P, Renauld J, Constantinescu S, Octave J, Kienlen-Campard P. Contribution of Kunitz Protease Inhibitor and Transmembrane Domains to Amyloid Precursor Protein Homodimerization. NEURODEGENER DIS 2012; 10:92-5. [DOI: 10.1159/000335225] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 11/18/2011] [Indexed: 11/19/2022] Open
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Libeu CP, Poksay KS, John V, Bredesen DE. Structural and functional alterations in amyloid-β precursor protein induced by amyloid-β peptides. J Alzheimers Dis 2011; 25:547-66. [PMID: 21471643 DOI: 10.3233/jad-2011-101938] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Alzheimer's disease-associated amyloid-β (Aβ) peptide is neurotoxic as an oligomer, but not as a monomer, by an unknown mechanism. We showed previously that Aβ interacts with the amyloid-β precursor protein (AβPP), leading to caspase cleavage and cell death induction. To characterize this structure and interaction further, we purified the extracellular domain of AβPP695 (eAβPP) and its complex with Aβ oligomers (AβOs) of varying sizes, and then performed small angle X-ray scattering (SAXS). In the absence of any Aβ, eAβPP was a compact homodimer with a tight association between the E1 and E2 domains. Dimeric Aβ oligomers induced monomerization of eAβPP while larger oligomers also bound eAβPP but preserved the homodimer. Efficient binding of the larger oligomers correlated with the presence of prefibrillar oligomers, suggesting that the eAβPP binding is limited to a conformational subset of Aβ oligomers. Both forms of Aβ bound to eAβPP at the Aβ-cognate region and induced dissociation of the E1 and E2 domains. Our data provide the first structural evidence for Aβ-AβPP binding and suggest a mechanism for differential modulation of AβPP processing and cell death signaling by Aβ dimers versus conformationally-specific larger oligomers.
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29
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Ben Khalifa N, Tyteca D, Marinangeli C, Depuydt M, Collet JF, Courtoy PJ, Renauld JC, Constantinescu S, Octave JN, Kienlen-Campard P. Structural features of the KPI domain control APP dimerization, trafficking, and processing. FASEB J 2011; 26:855-67. [PMID: 22085646 DOI: 10.1096/fj.11-190207] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The two major isoforms of human APP, APP695 and APP751, differ by the presence of a Kunitz-type protease inhibitor (KPI) domain in the extracellular region. APP processing and function is thought to be regulated by homodimerization. We used bimolecular fluorescence complementation (BiFC) to study dimerization of different APP isoforms and mutants. APP751 was found to form significantly more homodimers than APP695. Mutation of dimerization motifs in the TM domain did not affect fluorescence complementation, but native folding of KPI is critical for APP751 homodimerization. APP751 and APP695 dimers were mostly localized at steady state in the Golgi region, suggesting that most of the APP751 and 695 dimers are in the secretory pathway. Mutation of the KPI led to the retention of the APP homodimers in the endoplasmic reticulum. We finally showed that APP751 is more efficiently processed through the nonamyloidogenic pathway than APP695. These findings provide new insight on the particular role of KPI domain in APP dimerization. The correlation observed between dimerization, subcellular localization, and processing suggests that dimerization acts as an efficient regulator of APP trafficking in the secretory compartments that has major consequences on its processing.
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Affiliation(s)
- Naouel Ben Khalifa
- Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
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30
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Abstract
Alzheimer's disease (AD), the leading cause of dementia worldwide, is characterized by the accumulation of the β-amyloid peptide (Aβ) within the brain along with hyperphosphorylated and cleaved forms of the microtubule-associated protein tau. Genetic, biochemical, and behavioral research suggest that physiologic generation of the neurotoxic Aβ peptide from sequential amyloid precursor protein (APP) proteolysis is the crucial step in the development of AD. APP is a single-pass transmembrane protein expressed at high levels in the brain and metabolized in a rapid and highly complex fashion by a series of sequential proteases, including the intramembranous γ-secretase complex, which also process other key regulatory molecules. Why Aβ accumulates in the brains of elderly individuals is unclear but could relate to changes in APP metabolism or Aβ elimination. Lessons learned from biochemical and genetic studies of APP processing will be crucial to the development of therapeutic targets to treat AD.
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31
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Ables JL, Breunig JJ, Eisch AJ, Rakic P. Not(ch) just development: Notch signalling in the adult brain. Nat Rev Neurosci 2011; 12:269-83. [PMID: 21505516 DOI: 10.1038/nrn3024] [Citation(s) in RCA: 323] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Notch pathway is often regarded as a developmental pathway, but components of Notch signalling are expressed and active in the adult brain. With the advent of more sophisticated genetic manipulations, evidence has emerged that suggests both conserved and novel roles for Notch signalling in the adult brain. Not surprisingly, Notch is a key regulator of adult neural stem cells, but it is increasingly clear that Notch signalling also has roles in the regulation of migration, morphology, synaptic plasticity and survival of immature and mature neurons. Understanding the many functions of Notch signalling in the adult brain, and its dysfunction in neurodegenerative disease and malignancy, is crucial to the development of new therapeutics that are centred around this pathway.
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Affiliation(s)
- Jessica L Ables
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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32
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Kaden D, Munter LM, Reif B, Multhaup G. The amyloid precursor protein and its homologues: structural and functional aspects of native and pathogenic oligomerization. Eur J Cell Biol 2011; 91:234-9. [PMID: 21459473 DOI: 10.1016/j.ejcb.2011.01.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 01/24/2011] [Accepted: 01/24/2011] [Indexed: 12/20/2022] Open
Abstract
Over the last 25 years, remarkable progress has been made not only in identifying key molecules of Alzheimer's disease but also in understanding their meaning in the pathogenic state. One hallmark of Alzheimer pathology is the amyloid plaque. A major component of the extracellular deposit is the amyloid-β (Aβ) peptide which is generated from its larger precursor molecule, i.e., the amyloid precursor protein (APP) by consecutive cleavages. Processing is exerted by two enzymes, i.e., the β-secretase and the γ-secretase. We and others have found that the self-association of the amyloid peptide and the dimerization and oligomerization of these proteins is a key factor under native and pathogenic conditions. In particular, the Aβ homodimer represents a nidus for plaque formation and a well defined therapeutic target. Further, dimerization of the APP was reported to increase generation of toxic Aβ whereas heterodimerization with its homologues amyloid precursor like proteins (APLP1 and APLP2) decreased Aβ formation. This review mainly focuses on structural features of the homophilic and heterophilic interactions among APP family proteins. The proposed contact sites are described and the consequences of protein dimerization on their functions and in the pathogenesis of Alzheimer's disease are discussed.
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Affiliation(s)
- Daniela Kaden
- Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
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33
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Munter LM, Botev A, Richter L, Hildebrand PW, Althoff V, Weise C, Kaden D, Multhaup G. Aberrant amyloid precursor protein (APP) processing in hereditary forms of Alzheimer disease caused by APP familial Alzheimer disease mutations can be rescued by mutations in the APP GxxxG motif. J Biol Chem 2010; 285:21636-43. [PMID: 20452985 PMCID: PMC2898405 DOI: 10.1074/jbc.m109.088005] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 05/07/2010] [Indexed: 01/01/2023] Open
Abstract
The identification of hereditary familial Alzheimer disease (FAD) mutations in the amyloid precursor protein (APP) and presenilin-1 (PS1) corroborated the causative role of amyloid-beta peptides with 42 amino acid residues (Abeta42) in the pathogenesis of AD. Although most FAD mutations are known to increase Abeta42 levels, mutations within the APP GxxxG motif are known to lower Abeta42 levels by attenuating transmembrane sequence dimerization. Here, we show that aberrant Abeta42 levels of FAD mutations can be rescued by GxxxG mutations. The combination of the APP-GxxxG mutation G33A with APP-FAD mutations yielded a constant 60% decrease of Abeta42 levels and a concomitant 3-fold increase of Abeta38 levels compared with the Gly(33) wild-type as determined by ELISA. In the presence of PS1-FAD mutations, the effects of G33A were attenuated, apparently attributable to a different mechanism of PS1-FAD mutants compared with APP-FAD mutants. Our results contribute to a general understanding of the mechanism how APP is processed by the gamma-secretase module and strongly emphasize the potential of the GxxxG motif in the prevention of sporadic AD as well as FAD.
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Affiliation(s)
- Lisa-Marie Munter
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany and
| | - Anne Botev
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany and
| | - Luise Richter
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany and
| | - Peter W. Hildebrand
- the Institut für Medizinische Physik und Biophysik, Charité, 10117 Berlin, Germany
| | - Veit Althoff
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany and
| | - Christoph Weise
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany and
| | - Daniela Kaden
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany and
| | - Gerd Multhaup
- From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany and
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34
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Vidi PA, Przybyla JA, Hu CD, Watts VJ. Visualization of G protein-coupled receptor (GPCR) interactions in living cells using bimolecular fluorescence complementation (BiFC). ACTA ACUST UNITED AC 2010; Chapter 5:Unit 5.29. [PMID: 20373507 DOI: 10.1002/0471142301.ns0529s51] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Members of the G protein-coupled receptor (GPCR) superfamily have been shown to homo- and hetero-oligomerize both in vitro and in vivo. Although the functional and pharmacological significance of GPCR oligomerization is far from being completely understood, evidence suggests that, depending on the receptor, oligomerization may influence ligand binding, G protein coupling, and receptor targeting. Bimolecular fluorescence complementation (BiFC) is a technique based on the complementation of fragments from fluorescent proteins that allows the measurement and visualization of protein interactions in living cells. It can be extended to the simultaneous detection of distinct protein-protein interactions using a multicolor setup. This unit describes the application of BiFC and multicolor BiFC to the visualization of GPCR oligomerization in a neuronal cell model. Oligomerization of GPCR fusions to BiFC tags is visualized and measured using fluorescence microscopy and fluorometry. The effect of ligands on the relative formation of distinct oligomeric species is monitored with a ratiometric multicolor BiFC approach.
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35
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Gonçalves SA, Matos JE, Outeiro TF. Zooming into protein oligomerization in neurodegeneration using BiFC. Trends Biochem Sci 2010; 35:643-51. [PMID: 20561791 DOI: 10.1016/j.tibs.2010.05.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 05/10/2010] [Accepted: 05/13/2010] [Indexed: 11/25/2022]
Abstract
Several neurodegenerative diseases are characterized by the accumulation of misfolded and aggregated proteins, which lead to neurotoxicity. However, the nature of those toxic species is controversial. Developments in optical microscopy and live-cell imaging are essential in providing crucial insight into the molecular mechanisms involved. In particular, the technique of bimolecular fluorescence complementation (BiFC) represents a remarkable improvement for observing protein-protein interactions within living cells. Unlike other techniques, BiFC provides spatial and temporal resolution and can be carried out in a physiological environment. Among other applications, BiFC has been used to study molecular determinants of oligomerization in neurodegenerative disorders, thereby promising to unveil novel targets for therapeutics. We review the applicability of BiFC for investigating the molecular basis of neurodegenerative diseases associated with protein misfolding and aggregation.
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Affiliation(s)
- Susana A Gonçalves
- Cell and Molecular Neuroscience Unit, Instituto de Medicina Molecular, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
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36
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Hanley SC, Austin E, Assouline-Thomas B, Kapeluto J, Blaichman J, Moosavi M, Petropavlovskaia M, Rosenberg L. {beta}-Cell mass dynamics and islet cell plasticity in human type 2 diabetes. Endocrinology 2010; 151:1462-72. [PMID: 20176718 DOI: 10.1210/en.2009-1277] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Studies of long-standing type 2 diabetes (T2D) report a deficit in beta-cell mass due to increased apoptosis, whereas neogenesis and replication are unaffected. It is unclear whether these changes are a cause or a consequence of T2D. Moreover, whereas islet morphogenetic plasticity has been demonstrated in vitro, the in situ plasticity of islets, as well as the effect of T2D on endocrine differentiation, is unknown. We compared beta-cell volume, neogenesis, replication, and apoptosis in pancreata from lean and obese (body mass index > or = 27 kg/m(2)) diabetic (5 +/- 2 yr since diagnosis) and nondiabetic cadaveric donors. We also subjected isolated islets from diabetic (3 +/- 1 yr since diagnosis) and nondiabetic donors to an established in vitro model of islet plasticity. Differences in beta-cell volume between diabetic and nondiabetic donors were consistently less pronounced than those reported in long-standing T2D. A compensatory increase in beta-cell neogenesis appeared to mediate this effect. Studies of induced plasticity indicated that islets from diabetic donors were capable of epithelial dedifferentiation but did not demonstrate regenerative potential, as was seen in islets from nondiabetic donors. This deficiency was associated with the overexpression of Notch signaling molecules and a decreased neurogenin-3(+) cell frequency. One interpretation of these results would be that decreased beta-cell volume is a consequence, not a cause, of T2D, mediated by increased apoptosis and attenuated beta-cell (re)generation. However, other explanations are also possible. It remains to be seen whether the morphogenetic plasticity of human islets, deficient in vitro in islets from diabetic donors, is a component of normal beta-cell mass dynamics.
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Affiliation(s)
- Stephen C Hanley
- M.Eng., Montréal General Hospital C9-128, 1650 Cedar Avenue, Montréal, Québec, Canada H3G 1A4
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37
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Kosel D, Heiker JT, Juhl C, Wottawah CM, Blüher M, Mörl K, Beck-Sickinger AG. Dimerization of adiponectin receptor 1 is inhibited by adiponectin. J Cell Sci 2010; 123:1320-8. [PMID: 20332107 DOI: 10.1242/jcs.057919] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AdipoR1 and AdipoR2 are newly discovered members of the huge family of seven-transmembrane receptors, but both receptors are structurally and functionally different from G-protein-coupled receptors. Little is known about the oligomerization of the AdipoRs. Here, we show the presence of endogenous AdipoR1 dimers in various cell lines and human muscle tissue. To directly follow and localize the dimerization, we applied bimolecular fluorescence complementation (BiFC) in combination with flow cytometry. We visualized and quantified AdipoR1 homodimers in HEK293 cells. Moreover, we identified a GxxxG dimerization motif in the fifth transmembrane domain of the AdipoR1. By mutating both glycine residues to phenylalanine or glutamic acid, we were able to modulate the dimerization of AdipoR1, implicating a role for the GxxxG motif in AdipoR1 dimerization. Furthermore, we tested whether the AdipoR1 ligand adiponectin had any influence on receptor dimerization. Interestingly, we found that adiponectin decreases the receptor dimerization in a concentration-dependent manner. This effect is mainly mediated by segments of the collagen-like domain of full-length adiponectin. Accordingly, this is the first direct read-out signal of adiponectin at the AdipoR1 receptor, which revealed the involvement of specific amino acids of both the receptor and the ligand to modulate the quaternary structure of the AdipoR1.
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Affiliation(s)
- David Kosel
- Faculty of Biosciences, Institute of Biochemistry, Leipzig University, Brüderstr 34, 04103 Leipzig, Germany
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38
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Oh SY, Chen CD, Abraham CR. Cell-type dependent modulation of Notch signaling by the amyloid precursor protein. J Neurochem 2010; 113:262-74. [PMID: 20089128 DOI: 10.1111/j.1471-4159.2010.06603.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The amyloid precursor protein is a ubiquitously expressed transmembrane protein that has been long implicated in the pathogenesis of Alzheimer's disease but its normal biological function has remained elusive despite extensive effort. We have previously reported the identification of Notch2 as an amyloid precursor protein interacting protein in E18 rat neurons. Here, we sought to reveal the physiologic consequences of this interaction. We report a functional relationship between amyloid precursor protein and Notch1, which does not affect Delta ligand binding. First, we observed interactions between the amyloid precursor protein and Notch in mouse embryonic stem cells lacking both presenilin 1 and presenilin 2, the active proteolytic components of the gamma-secretase complex, suggesting that these two transmembrane proteins can interact in the absence of presenilin. Next, we demonstrated that the amyloid precursor protein affects Notch signaling by using Notch-dependent luciferase assays in two cell lines, the human embryonic kidney 293 and the monkey kidney, COS7. We found that the amyloid precursor protein exerts opposing effects on Notch signaling in human embryonic kidney 293 vs. COS7 cells. Finally, we show that more Notch Intracellular Domain is found in the nucleus in the presence of exogenous amyloid precursor protein or its intracellular domain, suggesting the mechanism by which the amyloid precursor protein affects Notch signaling in certain cells. Our results provide evidence of potentially important communications between the amyloid precursor protein and Notch.
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Affiliation(s)
- Sun Young Oh
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA
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39
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Reversal of learning deficits in hAPP transgenic mice carrying a mutation at Asp664: a role for early experience. Behav Brain Res 2009; 206:202-7. [PMID: 19751769 DOI: 10.1016/j.bbr.2009.09.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 09/04/2009] [Accepted: 09/07/2009] [Indexed: 11/21/2022]
Abstract
In addition to the cleavages that generate amyloid-beta (Abeta), the Abeta-precursor protein (APP) is processed at Asp664, releasing a second toxic peptide (APP-C31). Transgenic mice otherwise identical to a well-characterized model of AD, PDAPP mice, but carrying a mutation that obliterates Asp664 show a reversal of AD-like deficits in memory and in non-cognitive components of behaviour in spite of accumulating high levels of Abeta. These results suggest that cleavage of APP at Asp664 plays a role in the generation of AD-like deficits, and that a major pathway of Abeta toxicity in vivo, or a pathway that crucially impinges on it, may depend on cleavage of APP at Asp664. Since young PDAPP(D664A) mice showed an akinetic phenotype when first required to swim, we trained a 3-month-old (mo) cohort to criterion (normal swimming), and briefly exposed it to the Morris water maze (MWM) environment prior to training at 7 mo, to avoid potentially confounding effects of the akinetic phenotype in MWM studies. Prior experience decreased floating in PDAPP(D664A) mice but not in PDAPP nor in non-Tg groups. While learning was restored in experienced PDAPP(D664A) mice, it was indistinguishable from both non-Tg as well as from PDAPP mice in naïve PDAPP(D664A) animals. Floating did not correlate with worse performance in naïve PDAPP(D664A) mice, suggesting that the contribution of prior experience to improved performance is related to its cognitive effects but not to non-cognitive components of behaviour. Our results suggest that early experience reduces the contribution of non-cognitive components of behaviour to performance, and may contribute to the restoration of learning at later ages in PDAPP(D664A) mice.
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40
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Gralle M, Botelho MG, Wouters FS. Neuroprotective secreted amyloid precursor protein acts by disrupting amyloid precursor protein dimers. J Biol Chem 2009; 284:15016-25. [PMID: 19336403 DOI: 10.1074/jbc.m808755200] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The amyloid precursor protein (APP) is implied both in cell growth and differentiation and in neurodegenerative processes in Alzheimer disease. Regulated proteolysis of APP generates biologically active fragments such as the neuroprotective secreted ectodomain sAPPalpha and the neurotoxic beta-amyloid peptide. Furthermore, it has been suggested that the intact transmembrane APP plays a signaling role, which might be important for both normal synaptic plasticity and neuronal dysfunction in dementia. To understand APP signaling, we tracked single molecules of APP using quantum dots and quantitated APP homodimerization using fluorescence lifetime imaging microscopy for the detection of Förster resonance energy transfer in living neuroblastoma cells. Using selective labeling with synthetic fluorophores, we show that the dimerization of APP is considerably higher at the plasma membrane than in intracellular membranes. Heparan sulfate significantly contributes to the almost complete dimerization of APP at the plasma membrane. Importantly, this technique for the first time structurally defines the initiation of APP signaling by binding of a relevant physiological extracellular ligand; our results indicate APP as receptor for neuroprotective sAPPalpha, as sAPPalpha binding disrupts APP dimers, and this disruption of APP dimers by sAPPalpha is necessary for the protection of neuroblastoma cells against starvation-induced cell death. Only cells expressing reversibly dimerized wild-type, but not covalently dimerized mutant APP are protected by sAPPalpha. These findings suggest a potentially beneficial effect of increasing sAPPalpha production or disrupting APP dimers for neuronal survival.
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Affiliation(s)
- Matthias Gralle
- Laboratory for Molecular and Cellular Systems, Department of Neurophysiology and Sensory Physiology, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
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41
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Vidi PA, Watts VJ. Fluorescent and bioluminescent protein-fragment complementation assays in the study of G protein-coupled receptor oligomerization and signaling. Mol Pharmacol 2009; 75:733-9. [PMID: 19141658 DOI: 10.1124/mol.108.053819] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Most cellular functions, including signaling by G protein-coupled receptors (GPCRs), are mediated by protein-protein interactions, making the identification and localization of protein complexes key to the understanding of cellular processes. In complement to traditional biochemical techniques, noninvasive resonance energy transfer (RET) and protein-fragment complementation assays (PCAs) now allow protein interactions to be detected in the context of living cells. In this review, fluorescent and bioluminescent PCAs are discussed and their application illustrated with studies on GPCR signaling. Newly developed techniques combining PCA and RET assays for the detection of ternary and quaternary protein complexes are also presented.
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Affiliation(s)
- Pierre-Alexandre Vidi
- Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences, Purdue University, West Lafayette, Indiana 47907-2051, USA
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42
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Kaden D, Voigt P, Munter LM, Bobowski KD, Schaefer M, Multhaup G. Subcellular localization and dimerization of APLP1 are strikingly different from APP and APLP2. J Cell Sci 2009; 122:368-77. [PMID: 19126676 DOI: 10.1242/jcs.034058] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The molecular association between APP and its mammalian homologs has hardly been explored. In systematically addressing this issue, we show by live cell imaging that APLP1 mainly localizes to the cell surface, whereas APP and APLP2 are mostly found in intracellular compartments. Homo- and heterotypic cis interactions of APP family members could be detected by FRET and co-immunoprecipitation analysis and occur in a modular mode. Only APLP1 formed trans interactions, supporting the argument for a putative specific role of APLP1 in cell adhesion. Deletion mutants of APP family members revealed two highly conserved regions as important for the protein crosstalk. In particular, the N-terminal half of the ectodomain was crucial for APP and APLP2 interactions. By contrast, multimerization of APLP1 was only partially dependent on this domain but strongly on the C-terminal half of the ectodomain. We further observed that coexpression of APP with APLP1 or APLP2 leads to diminished generation of Abeta42. The current data suggest that this is due to the formation of heteromeric complexes, opening the way for novel therapeutic strategies targeting these complexes.
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Affiliation(s)
- Daniela Kaden
- Institut für Chemie und Biochemie, Freie Universität Berlin, Berlin, Germany
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43
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Bakota L, Brandt R. Chapter 2 Live‐Cell Imaging in the Study of Neurodegeneration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 276:49-103. [DOI: 10.1016/s1937-6448(09)76002-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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44
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Kerppola TK. Bimolecular fluorescence complementation (BiFC) analysis as a probe of protein interactions in living cells. Annu Rev Biophys 2008; 37:465-87. [PMID: 18573091 DOI: 10.1146/annurev.biophys.37.032807.125842] [Citation(s) in RCA: 496] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protein interactions are a fundamental mechanism for the generation of biological regulatory specificity. The study of protein interactions in living cells is of particular significance because the interactions that occur in a particular cell depend on the full complement of proteins present in the cell and the external stimuli that influence the cell. Bimolecular fluorescence complementation (BiFC) analysis enables direct visualization of protein interactions in living cells. The BiFC assay is based on the association between two nonfluorescent fragments of a fluorescent protein when they are brought in proximity to each other by an interaction between proteins fused to the fragments. Numerous protein interactions have been visualized using the BiFC assay in many different cell types and organisms. The BiFC assay is technically straightforward and can be performed using standard molecular biology and cell culture reagents and a regular fluorescence microscope or flow cytometer.
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Affiliation(s)
- Tom K Kerppola
- Howard Hughes Medical Institute and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0650, USA.
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45
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Makarova A, Bercury KK, Adams KW, Joyner D, Deng M, Spoelgen R, Koker M, Strickland DK, Hyman BT. The LDL receptor-related protein can form homo-dimers in neuronal cells. Neurosci Lett 2008; 442:91-5. [PMID: 18602448 DOI: 10.1016/j.neulet.2008.06.070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Revised: 06/13/2008] [Accepted: 06/18/2008] [Indexed: 10/21/2022]
Abstract
The ability of the low density lipoprotein receptor-related protein (LRP) to form homo-dimers was studied in mouse neuroblastoma and human neuroglioma cells as well as in primary cortical cultures from adult mouse brain. Homo-dimerization of LRP light chain (LC) was shown by several methods including co-immunoprecipitation, fluorescence lifetime imaging microscopy, and bimolecular fluorescence complementation assay. The requirement of intact NPXY motifs of LRP LC for homo-dimerization was ruled out by co-immunoprecipitation assay.
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Affiliation(s)
- Alexandra Makarova
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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46
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Galvan V, Zhang J, Gorostiza OF, Banwait S, Huang W, Ataie M, Tang H, Bredesen DE. Long-term prevention of Alzheimer's disease-like behavioral deficits in PDAPP mice carrying a mutation in Asp664. Behav Brain Res 2008; 191:246-55. [PMID: 18485495 DOI: 10.1016/j.bbr.2008.03.035] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 03/25/2008] [Accepted: 03/28/2008] [Indexed: 11/20/2022]
Abstract
The deficits of Alzheimer's disease (AD) are believed to result, at least in part, from neurotoxicity of beta-amyloid (Abeta), a set of 38-43 amino acid fragments derived from the beta-amyloid precursor protein (APP). In addition, APP generates the APP-C31 and Jcasp toxic fragments intracellularly by cleavage at Asp664. We reported that mutation of Asp664 to Ala in a FAD-human APP transgene prevented AD-like deficits but did not affect Abeta production or deposition in PDAPP mice, arguing that D664A plays a crucial role in the generation of AD-like deficits. Whether D664A simply delays or completely prevents AD-like deficits, however, remained undefined. To address this question, we performed behavioral studies longitudinally on a pretrained mouse cohort at 9 and 13 months (mo) of age. While behavioral deficits were present in PDAPP mice, performance of Tg PDAPP(D664A) mice was not significantly different from non-Tg littermates' across all ages tested. Moreover, aberrant patterns in non-cognitive components of behavior in PDAPP mice were ameliorated in PDAPP(D664A) animals as well. A trend towards poorer retention at 9 mo and poorer learning at 13 mo that did not reach statistical significance was observed in PDAPP(D664A) mice. These results support and extend recent studies showing that cleavage of APP at Asp664 (or protein-protein interactions dependent on Asp664) is a crucial event in the generation of AD-like deficits in PDAPP mice. Our results thus further demonstrate that the D664A mutation either completely precludes, or markedly delays (beyond 13 mo) the appearance of AD-like deficits in this mouse model of AD.
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Affiliation(s)
- Veronica Galvan
- Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA.
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Zerbinatti CV, Cordy JM, Chen CD, Guillily M, Suon S, Ray WJ, Seabrook GR, Abraham CR, Wolozin B. Oxysterol-binding protein-1 (OSBP1) modulates processing and trafficking of the amyloid precursor protein. Mol Neurodegener 2008; 3:5. [PMID: 18348724 PMCID: PMC2323375 DOI: 10.1186/1750-1326-3-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Accepted: 03/18/2008] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED BACKGROUND Evidence from biochemical, epidemiological and genetic findings indicates that cholesterol levels are linked to amyloid-beta (Abeta) production and Alzheimer's disease (AD). Oxysterols, which are cholesterol-derived ligands of the liver X receptors (LXRs) and oxysterol binding proteins, strongly regulate the processing of amyloid precursor protein (APP). Although LXRs have been studied extensively, little is known about the biology of oxysterol binding proteins. Oxysterol-binding protein 1 (OSBP1) is a member of a family of sterol-binding proteins with roles in lipid metabolism, regulation of secretory vesicle generation and signal transduction, and it is thought that these proteins may act as sterol sensors to control a variety of sterol-dependent cellular processes. RESULTS We investigated whether OSBP1 was involved in regulating APP processing and found that overexpression of OSBP1 downregulated the amyloidogenic processing of APP, while OSBP1 knockdown had the opposite effect. In addition, we found that OSBP1 altered the trafficking of APP-Notch2 dimers by causing their accumulation in the Golgi, an effect that could be reversed by treating cells with OSBP1 ligand, 25-hydroxycholesterol. CONCLUSION These results suggest that OSBP1 could play a role in linking cholesterol metabolism with intracellular APP trafficking and Abeta production, and more importantly indicate that OSBP1 could provide an alternative target for Abeta-directed therapeutic.
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Affiliation(s)
- Celina V Zerbinatti
- Department of Pharmacology, Boston University School of Medicine, Boston, MA, 02118, USA.
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Osterfield M, Egelund R, Young LM, Flanagan JG. Interaction of amyloid precursor protein with contactins and NgCAM in the retinotectal system. Development 2008; 135:1189-99. [PMID: 18272596 DOI: 10.1242/dev.007401] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The amyloid precursor protein (APP) plays a central role in Alzheimer's disease, but its actions in normal development are not well understood. Here, a tagged APP ectodomain was used to identify extracellular binding partners in developing chick brain. Prominent binding sites were seen in the olfactory bulb and on retinal axons growing into the optic tectum. Co-precipitation from these tissues and tandem mass spectrometry led to the identification of two associated proteins: contactin 4 and NgCAM. In vitro binding studies revealed direct interactions among multiple members of the APP and contactin protein families. Levels of the APP processing fragment, CTFalpha, were modulated by both contactin 4 and NgCAM. In the developing retinotectal system, APP, contactin 4 and NgCAM are expressed in the retina and tectum in suitable locations to interact. Functional assays revealed regulatory effects of both APP and contactin 4 on NgCAM-dependent growth of cultured retinal axons, demonstrating specific functional interactions among these proteins. These studies identify novel binding and functional interactions among proteins of the APP, contactin and L1CAM families, with general implications for mechanisms of APP action in neural development and disease.
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Affiliation(s)
- Miriam Osterfield
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
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Kerppola TK. Bimolecular fluorescence complementation: visualization of molecular interactions in living cells. Methods Cell Biol 2008; 85:431-70. [PMID: 18155474 DOI: 10.1016/s0091-679x(08)85019-4] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A variety of experimental methods have been developed for the analysis of protein interactions. The majority of these methods either require disruption of the cells to detect molecular interactions or rely on indirect detection of the protein interaction. The bimolecular fluorescence complementation (BiFC) assay provides a direct approach for the visualization of molecular interactions in living cells and organisms. The BiFC approach is based on the facilitated association between two fragments of a fluorescent protein when the fragments are brought together by an interaction between proteins fused to the fragments. The BiFC approach has been used for visualization of interactions among a variety of structurally diverse interaction partners in many different cell types. It enables detection of transient complexes as well as complexes formed by a subpopulation of the interaction partners. It is essential to include negative controls in each experiment in which the interface between the interaction partners has been mutated or deleted. The BiFC assay has been adapted for simultaneous visualization of multiple protein complexes in the same cell and the competition for shared interaction partners. A ubiquitin-mediated fluorescence complementation assay has also been developed for visualization of the covalent modification of proteins by ubiquitin family peptides. These fluorescence complementation assays have a great potential to illuminate a variety of biological interactions in the future.
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Affiliation(s)
- Tom K Kerppola
- Department of Biological Chemistry, Howard Hughes Medical Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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Affiliation(s)
- Michael S Wolfe
- Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
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