1
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Huang Z. Evidence that Alzheimer's Disease Is a Disease of Competitive Synaptic Plasticity Gone Awry. J Alzheimers Dis 2024; 99:447-470. [PMID: 38669548 PMCID: PMC11119021 DOI: 10.3233/jad-240042] [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] [Indexed: 04/28/2024]
Abstract
Mounting evidence indicates that a physiological function of amyloid-β (Aβ) is to mediate neural activity-dependent homeostatic and competitive synaptic plasticity in the brain. I have previously summarized the lines of evidence supporting this hypothesis and highlighted the similarities between Aβ and anti-microbial peptides in mediating cell/synapse competition. In cell competition, anti-microbial peptides deploy a multitude of mechanisms to ensure both self-protection and competitor elimination. Here I review recent studies showing that similar mechanisms are at play in Aβ-mediated synapse competition and perturbations in these mechanisms underpin Alzheimer's disease (AD). Specifically, I discuss evidence that Aβ and ApoE, two crucial players in AD, co-operate in the regulation of synapse competition. Glial ApoE promotes self-protection by increasing the production of trophic monomeric Aβ and inhibiting its assembly into toxic oligomers. Conversely, Aβ oligomers, once assembled, promote the elimination of competitor synapses via direct toxic activity and amplification of "eat-me" signals promoting the elimination of weak synapses. I further summarize evidence that neuronal ApoE may be part of a gene regulatory network that normally promotes competitive plasticity, explaining the selective vulnerability of ApoE expressing neurons in AD brains. Lastly, I discuss evidence that sleep may be key to Aβ-orchestrated plasticity, in which sleep is not only induced by Aβ but is also required for Aβ-mediated plasticity, underlining the link between sleep and AD. Together, these results strongly argue that AD is a disease of competitive synaptic plasticity gone awry, a novel perspective that may promote AD research.
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Affiliation(s)
- Zhen Huang
- Departments of Neuroscience and Neurology, University of Wisconsin-Madison, Madison, WI, USA
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2
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Revol RS, Koistinen NA, Menon PK, Chicote-Gonzàlez A, Iverfeldt K, Ström AL. Alpha-secretase dependent nuclear localization of the amyloid-β precursor protein-binding protein Fe65 promotes DNA repair. Mol Cell Neurosci 2023; 127:103903. [PMID: 37918552 DOI: 10.1016/j.mcn.2023.103903] [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: 06/14/2023] [Revised: 09/29/2023] [Accepted: 10/29/2023] [Indexed: 11/04/2023] Open
Abstract
Fe65 is a brain enriched adaptor protein involved in various cellular processes, including actin cytoskeleton regulation, DNA repair and transcription. A well-studied interacting partner of Fe65 is the transmembrane amyloid-β precursor protein (APP), which can undergo regulated intramembrane proteolysis (RIP). Following β- and γ-secretase-mediated RIP, the released APP intracellular domain (AICD) together with Fe65 can translocate to the nucleus and regulate transcription. In this study, we investigated if Fe65 nuclear localization can also be regulated by different α-secretases, also known to participate in RIP of APP and other transmembrane proteins. We found that in both Phorbol 12-myristate 13-acetate and all-trans retinoic acid differentiated neuroblastoma cells a strong negative impact on Fe65 nuclear localization, equal to the effect observed upon γ-secretase inhibition, could be detected following inhibition of all three (ADAM9, ADAM10 and ADAM17) α-secretases. Moreover, using the comet assay and analysis of Fe65 dependent DNA repair associated posttranslational modifications of histones, we could show that inhibition of α-secretase-mediated Fe65 nuclear translocation resulted in impaired capacity of the cells to repair DNA damage. Taken together this suggests that α-secretase processing of APP and/or other Fe65 interacting transmembrane proteins play an important role in regulating Fe65 nuclear translocation and DNA repair.
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Affiliation(s)
- Rebecca S Revol
- Stockholm University, Department of Biochemistry and Biophysics, 106 91 Stockholm, Sweden
| | - Niina A Koistinen
- Stockholm University, Department of Biochemistry and Biophysics, 106 91 Stockholm, Sweden
| | - Preeti K Menon
- Stockholm University, Department of Biochemistry and Biophysics, 106 91 Stockholm, Sweden
| | | | - Kerstin Iverfeldt
- Stockholm University, Department of Biochemistry and Biophysics, 106 91 Stockholm, Sweden
| | - Anna-Lena Ström
- Stockholm University, Department of Biochemistry and Biophysics, 106 91 Stockholm, Sweden.
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3
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Almenar-Queralt A, dos Santos Chaves R, Kwon EJ, Shah SB. Heads Up! Interlinked Amyloidogenic and Axonal Transport Pathways in Concussion-Induced Neurodegeneration. Neurosci Insights 2022; 17:26331055221129641. [PMID: 36274925 PMCID: PMC9580075 DOI: 10.1177/26331055221129641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 09/29/2022] [Indexed: 11/07/2022] Open
Abstract
Mild traumatic brain injury (mTBI), a condition in which brain function is transiently disrupted by a mechanical force, is a major risk factor for developing Alzheimer’s disease (AD) and other neurodegenerative conditions. In this commentary, we summarize recent findings in human neurons derived from induced pluripotent stem cells, detailing early neuronal events following mild injury that may seed future neurodegeneration. In particular, we discuss interlinked relationships between mTBI and several biological pathways hypothesized to underlie AD progression, including amyloidogenic cleavage of amyloid precursor protein (APP), impairment of axonal transport, and the development of APP-associated axonal swellings. We also describe the implications of these findings for future mechanistic and translational studies.
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Affiliation(s)
- Angels Almenar-Queralt
- Department of Pediatrics, University of California—San Diego, La Jolla, CA, USA,Sanford Consortium for Regenerative Medicine, University of California—San Diego, La Jolla, CA, USA
| | - Rodrigo dos Santos Chaves
- Sanford Consortium for Regenerative Medicine, University of California—San Diego, La Jolla, CA, USA,Department of Orthopaedic Surgery, University of California—San Diego, La Jolla, CA, USA
| | - Ester J. Kwon
- Sanford Consortium for Regenerative Medicine, University of California—San Diego, La Jolla, CA, USA,Department of Bioengineering, University of California—San Diego, La Jolla, CA, USA
| | - Sameer B Shah
- Department of Orthopaedic Surgery, University of California—San Diego, La Jolla, CA, USA,Department of Bioengineering, University of California—San Diego, La Jolla, CA, USA,Research Division, VA San Diego Healthcare System, San Diego, CA, USA,Sameer B Shah, Department of Orthopaedic Surgery, University of California, 9500 Gilman Drive MC 0863, La Jolla, CA 92093, USA.
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4
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Fernandez Bessone I, Navarro J, Martinez E, Karmirian K, Holubiec M, Alloatti M, Goto-Silva L, Arnaiz Yepez C, Martins-de-Souza D, Minardi Nascimento J, Bruno L, Saez TM, Rehen SK, Falzone TL. DYRK1A Regulates the Bidirectional Axonal Transport of APP in Human-Derived Neurons. J Neurosci 2022; 42:6344-6358. [PMID: 35803734 PMCID: PMC9398544 DOI: 10.1523/jneurosci.2551-21.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 06/01/2022] [Accepted: 06/17/2022] [Indexed: 11/21/2022] Open
Abstract
Dyrk1a triplication in Down's syndrome and its overexpression in Alzheimer's disease suggest a role for increased DYRK1A activity in the abnormal metabolism of APP. Transport defects are early phenotypes in the progression of Alzheimer's disease, which lead to APP processing impairments. However, whether DYRK1A regulates the intracellular transport and delivery of APP in human neurons remains unknown. From a proteomic dataset of human cerebral organoids treated with harmine, a DYRK1A inhibitor, we found expression changes in protein clusters associated with the control of microtubule-based transport and in close interaction with the APP vesicle. Live imaging of APP axonal transport in human-derived neurons treated with harmine or overexpressing a dominant negative DYRK1A revealed a reduction in APP vesicle density and enhanced the stochastic behavior of retrograde vesicle transport. Moreover, harmine increased the fraction of slow segmental velocities and changed speed transitions supporting a DYRK1A-mediated effect in the exchange of active motor configuration. Contrarily, the overexpression of DYRK1A in human polarized neurons increased the axonal density of APP vesicles and enhanced the processivity of retrograde APP. In addition, increased DYRK1A activity induced faster retrograde segmental velocities together with significant changes in slow to fast anterograde and retrograde speed transitions, suggesting the facilitation of the active motor configuration. Our results highlight DYRK1A as a modulator of the axonal transport machinery driving APP intracellular distribution in neurons, and stress DYRK1A inhibition as a putative therapeutic intervention to restore APP axonal transport in Down's syndrome and Alzheimer's disease.SIGNIFICANCE STATEMENT Axonal transport defects are early events in the progression of neurodegenerative diseases, such as Alzheimer's disease. However, the molecular mechanisms underlying transport defects remain elusive. Dyrk1a kinase is triplicated in Down's syndrome and overexpressed in Alzheimer's disease, suggesting that DYRK1A dysfunction affects molecular pathways leading to early-onset neurodegeneration. Here, we show by live imaging of human-derived neurons that DYRK1A activity differentially regulates the intracellular trafficking of APP. Further, single-particle analysis revealed DYRK1A as a modulator of axonal transport and the configuration of active motors within the APP vesicle. Our work highlights DYRK1A as a regulator of APP axonal transport and metabolism, supporting DYRK1A inhibition as a therapeutic strategy to restore intracellular dynamics in Alzheimer's disease.
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Affiliation(s)
- Iván Fernandez Bessone
- Instituto de Biología Celular y Neurociencia IBCN, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina C1121ABG
| | - Jordi Navarro
- Instituto de Biología Celular y Neurociencia IBCN, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina C1121ABG
| | - Emanuel Martinez
- Instituto de Biología Celular y Neurociencia IBCN, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina C1121ABG
| | - Karina Karmirian
- D'Or Institute for Research and Education, Rio de Janeiro, Brasil, RJ, 22281-100
- Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Brasil, RJ, 21941-902
| | - Mariana Holubiec
- Instituto de Biología Celular y Neurociencia IBCN, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina C1121ABG
| | - Matias Alloatti
- Instituto de Biología Celular y Neurociencia IBCN, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina C1121ABG
| | - Livia Goto-Silva
- D'Or Institute for Research and Education, Rio de Janeiro, Brasil, RJ, 22281-100
| | - Cayetana Arnaiz Yepez
- Instituto de Biología Celular y Neurociencia IBCN, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina C1121ABG
| | - Daniel Martins-de-Souza
- D'Or Institute for Research and Education, Rio de Janeiro, Brasil, RJ, 22281-100
- Laboratory of Neuroproteomics, University of Campinas Campinas, Brasil, SP, 13083-970
- Instituto Nacional de Biomarcadores Em Neuropsiquiatria, Conselho Nacional de Desenvolvimento Científico e Tecnológico, São Paulo, Brasil, SP, 13083-970
- Experimental Medicine Research Cluster, University of Campinas, Campinas, Brasil, SP, 13083-970
| | | | - Luciana Bruno
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina C1428EGA
| | - Trinidad M Saez
- Instituto de Biología Celular y Neurociencia IBCN, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina C1121ABG
| | - Stevens K Rehen
- D'Or Institute for Research and Education, Rio de Janeiro, Brasil, RJ, 22281-100
- Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Brasil, RJ, 21941-902
| | - Tomás L Falzone
- Instituto de Biología Celular y Neurociencia IBCN, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina C1121ABG
- Instituto de Investigación en Biomedicina de Buenos Aires, Partner Institute of the Max Planck Society, Buenos Aires, Argentina C1425FQD
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5
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Sultan F, Parkin ET. The Amyloid Precursor Protein Plays Differential Roles in the UVA
Resistance and Proliferation of Human Retinal Pigment Epithelial Cells. Protein Pept Lett 2022; 29:313-327. [DOI: 10.2174/0929866529666220217124152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/08/2021] [Accepted: 12/13/2021] [Indexed: 11/22/2022]
Abstract
Background:
Age-related macular degeneration (AMD) can be characterised by
degeneration of retinal pigment epithelial (RPE) cells and the accumulation, in retinal drusen
deposits, of amyloid beta-peptides proteolytically derived, by secretases, from the amyloid precursor
protein (APP). Ultraviolet (UV) light exposure is a risk factor for the development of AMD.
Objectives:
In the current study, we investigated whether APP and/or its proteolysis are linked to the
UVA resistance or proliferation of ARPE-19 human RPE cells.
Methods:
Cell viability was determined, following UVA exposure, with prior small interfering
RNA-mediated APP depletion or secretase inhibitor treatments. APP levels/proteolysis were
analysed by immunoblotting. Cells were also grown in the presence/absence of secretase inhibitors
to assess their effects on longer-term culture growth. Finally, the effects of APP proteolytic
fragments on ARPE-19 cell proliferation were monitored following co-culture with human
embryonic kidney cells stably over-expressing these fragments.
Results:
Endogenous APP was depleted following UVA irradiation and β-secretase, but not α-
secretase, and the processing of the protein was reduced. Experimental APP depletion or γ-secretase
(but not α- or β-secretase) inhibition ablated the detrimental effect of UVA on cell viability. In
contrast, α-secretase, and possibly γ-secretase but not β-secretase activity, appeared to promote the
longer-term proliferation of ARPE-19 cells in the absence of UVA irradiation.
Conclusions:
There are clear but differential links between APP expression/proteolysis and the
proliferation and UVA resistance of ARPE-19 cells indicating that the protein should be
investigated further in relation to the identification of possible drug targets for the treatment of
AMD.
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Affiliation(s)
- Fatima Sultan
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, United
Kingdom
| | - Edward T. Parkin
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, United
Kingdom
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6
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Ahmad F, Liu P. Synaptosome as a tool in Alzheimer's disease research. Brain Res 2020; 1746:147009. [PMID: 32659233 DOI: 10.1016/j.brainres.2020.147009] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/21/2020] [Accepted: 07/04/2020] [Indexed: 12/29/2022]
Abstract
Synapse dysfunction is an integral feature of Alzheimer's disease (AD) pathophysiology. In fact, prodromal manifestation of structural and functional deficits in synapses much prior to appearance of overt pathological hallmarks of the disease indicates that AD might be considered as a degenerative disorder of the synapses. Several research instruments and techniques have allowed us to study synaptic function and plasticity and their alterations in pathological conditions, such as AD. One such tool is the biochemically isolated preparations of detached and resealed synaptic terminals, the "synaptosomes". Because of the preservation of many of the physiological processes such as metabolic and enzymatic activities, synaptosomes have proved to be an indispensable ex vivo model system to study synapse physiology both when isolated from fresh or cryopreserved tissues, and from animal or human post-mortem tissues. This model system has been tremendously successful in the case of post-mortem tissues because of their accessibility relative to acute brain slices or cultures. The current review details the use of synaptosomes in AD research and its potential as a valuable tool in furthering our understanding of the pathogenesis and in devising and testing of therapeutic strategies for the disease.
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Affiliation(s)
- Faraz Ahmad
- Department of Anatomy, School of Biomedical Sciences, Brain Research New Zealand, University of Otago, Dunedin, New Zealand.
| | - Ping Liu
- Department of Anatomy, School of Biomedical Sciences, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
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7
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Saez TMM, Fernandez Bessone I, Rodriguez MS, Alloatti M, Otero MG, Cromberg LE, Pozo Devoto VM, Oubiña G, Sosa L, Buffone MG, Gelman DM, Falzone TL. Kinesin-1-mediated axonal transport of CB1 receptors is required for cannabinoid-dependent axonal growth and guidance. Development 2020; 147:dev184069. [PMID: 32265198 PMCID: PMC7188441 DOI: 10.1242/dev.184069] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 02/23/2020] [Indexed: 12/14/2022]
Abstract
Endocannabinoids (eCB) modulate growth cone dynamics and axonal pathfinding through the stimulation of cannabinoid type-1 receptors (CB1R), the function of which depends on their delivery and precise presentation at the growth cone surface. However, the mechanism involved in the axonal transport of CB1R and its transport role in eCB signaling remains elusive. As mutations in the kinesin-1 molecular motor have been identified in patients with abnormal cortical development and impaired white matter integrity, we studied the defects in axonal pathfinding and fasciculation in mice lacking the kinesin light chain 1 (Klc1-/-) subunit of kinesin-1. Reduced levels of CB1R were found in corticofugal projections and axonal growth cones in Klc1-/- mice. By live-cell imaging of CB1R-eGFP we characterized the axonal transport of CB1R vesicles and described the defects in transport that arise after KLC1 deletion. Cofilin activation, which is necessary for actin dynamics during growth cone remodeling, is impaired in the Klc1-/- cerebral cortex. In addition, Klc1-/- neurons showed expanded growth cones that were unresponsive to CB1R-induced axonal elongation. Together, our data reveal the relevance of kinesin-1 in CB1R axonal transport and in eCB signaling during brain wiring.
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Affiliation(s)
- Trinidad M M Saez
- Instituto de Biología Celular y Neurociencia, IBCN (UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, CP 1121 Buenos Aires, Argentina
| | - Iván Fernandez Bessone
- Instituto de Biología Celular y Neurociencia, IBCN (UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, CP 1121 Buenos Aires, Argentina
| | - María S Rodriguez
- Instituto de Biología Celular y Neurociencia, IBCN (UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, CP 1121 Buenos Aires, Argentina
| | - Matías Alloatti
- Instituto de Biología Celular y Neurociencia, IBCN (UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, CP 1121 Buenos Aires, Argentina
| | - María G Otero
- Instituto de Biología Celular y Neurociencia, IBCN (UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, CP 1121 Buenos Aires, Argentina
| | - Lucas E Cromberg
- Instituto de Biología Celular y Neurociencia, IBCN (UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, CP 1121 Buenos Aires, Argentina
| | - Victorio M Pozo Devoto
- Instituto de Biología Celular y Neurociencia, IBCN (UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, CP 1121 Buenos Aires, Argentina
| | - Gonzalo Oubiña
- Instituto de Biología y Medicina Experimental, IBYME (CONICET), CP 1428 Buenos Aires, Argentina
| | - Lucas Sosa
- Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, CP 5000 Córdoba, Argentina
| | - Mariano G Buffone
- Instituto de Biología y Medicina Experimental, IBYME (CONICET), CP 1428 Buenos Aires, Argentina
| | - Diego M Gelman
- Instituto de Biología y Medicina Experimental, IBYME (CONICET), CP 1428 Buenos Aires, Argentina
| | - Tomás L Falzone
- Instituto de Biología Celular y Neurociencia, IBCN (UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, CP 1121 Buenos Aires, Argentina
- Instituto de Biología y Medicina Experimental, IBYME (CONICET), CP 1428 Buenos Aires, Argentina
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8
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Hansen T, Thant C, White JA, Banerjee R, Thuamsang B, Gunawardena S. Excess active P13K rescues huntingtin-mediated neuronal cell death but has no effect on axonal transport defects. Apoptosis 2020; 24:341-358. [PMID: 30725352 DOI: 10.1007/s10495-019-01520-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
High levels of oxidative stress is detected in neurons affected by many neurodegenerative diseases, including huntington's disease. Many of these diseases also show neuronal cell death and axonal transport defects. While nuclear inclusions/accumulations likely cause cell death, we previously showed that cytoplasmic axonal accumulations can also contribute to neuronal death. However, the cellular mechanisms responsible for activating cell death is unclear. One possibility is that perturbations in normal axonal transport alter the function of the phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT)-pathway, a signal transduction pathway that promotes survival/growth in response to extracellular signals. To test this proposal in vivo, we expressed active PI3K in the context of pathogenic huntingtin (HTT-138Q) in Drosophila larval nerves, which show axonal transport defects and neuronal cell death. We found that excess expression of active P13K significantly suppressed HTT-138Q-mediated neuronal cell death, but had no effect on HTT-138Q-mediated axonal transport defects. Expression of active PI3K also rescued Paraquat-mediated cell death. Further, increased levels of pSer9 (inactive) glycogen synthase kinase 3β was seen in HTT-138Q-mediated larval brains, and in dynein loss of function mutants, indicating the modulation of the pro-survival pathway. Intriguingly, proteins in the PI3K/AKT-pathway showed functional interactions with motor proteins. Taken together our observations suggest that proper axonal transport is likely essential for the normal function of the pro-survival PI3K/AKT-signaling pathway and for neuronal survival in vivo. These results have important implications for targeting therapeutics to early insults during neurodegeneration and death.
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Affiliation(s)
- Timothy Hansen
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, US
| | - Claire Thant
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, US
| | - Joseph A White
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, US
| | - Rupkatha Banerjee
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, US
| | - Bhasirie Thuamsang
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, US
| | - Shermali Gunawardena
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, US. .,The State University of New York at Buffalo, 109 Cooke Hall, North/Amherst Campus, Buffalo, NY, 14260, US.
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9
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Marzo MG, Griswold JM, Ruff KM, Buchmeier RE, Fees CP, Markus SM. Molecular basis for dyneinopathies reveals insight into dynein regulation and dysfunction. eLife 2019; 8:47246. [PMID: 31364990 PMCID: PMC6733598 DOI: 10.7554/elife.47246] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/30/2019] [Indexed: 12/22/2022] Open
Abstract
Cytoplasmic dynein plays critical roles within the developing and mature nervous systems, including effecting nuclear migration, and retrograde transport of various cargos. Unsurprisingly, mutations in dynein are causative of various developmental neuropathies and motor neuron diseases. These ‘dyneinopathies’ define a broad spectrum of diseases with no known correlation between mutation identity and disease state. To circumvent complications associated with dynein studies in human cells, we employed budding yeast as a screening platform to characterize the motility properties of seventeen disease-correlated dynein mutants. Using this system, we determined the molecular basis for several classes of etiologically related diseases. Moreover, by engineering compensatory mutations, we alleviated the mutant phenotypes in two of these cases, one of which we confirmed with recombinant human dynein. In addition to revealing molecular insight into dynein regulation, our data provide additional evidence that the type of disease may in fact be dictated by the degree of dynein dysfunction. Motor proteins maintain order by transporting biomolecules and various structures within living cells. Dynein is one such motor that moves many types of cargoes along tracks called microtubules, which are spread across the cell’s interior. This motor is particularly important in nerve cells, which can be very long and thus depend heavily on motor proteins to ensure cargoes end up where they are needed. This becomes especially apparent in human diseases that arise as a consequence of mutations in the genes that produce components of the dynein motor. It is assumed that these genetic changes simply prevent dynein from working properly, which ultimately affects the health and survival of cells. However, it is currently unknown what specific effect these mutations have on dynein’s role within the cell, and how these changes lead to particular diseases. Marzo et al. have now used dynein from a budding yeast to closely examine 17 mutations in the dynein gene that are associated with developmental and/or motor neuron diseases in humans. For each mutation, various aspects of how dynein moves (e.g. average speed, distance travelled) were measured and quantitatively compared. The results show that the severity of the effect of each mutation can be directly correlated with the type of disease caused by the mutation. In particular, mutations that lead to less severe defects are found in patients that suffer from various motor neuron diseases, while more severe dynein mutations are found in patients with developmental brain disorders. Marzo et al. confirmed the likely structural changes that caused the defects in dynein’s activity in two of the 17 cases, by engineering additional, restorative mutations that lessened the effects of the primary mutation. These findings reveal links between the molecular impact of defects in the dynein gene and human health. They also confirm that budding yeast is a powerful tool for investigating newly discovered dynein mutations that correlate with disease. This study provides a potential system that could be used to screen drugs that might lessen the effects of specific dynein mutations. However, further work is needed to determine how effective this system will be for drug discovery.
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Affiliation(s)
- Matthew G Marzo
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Jacqueline M Griswold
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Kristina M Ruff
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Rachel E Buchmeier
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Colby P Fees
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, United States
| | - Steven M Markus
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
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10
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Penserga T, Kudumala SR, Poulos R, Godenschwege TA. A Role for Drosophila Amyloid Precursor Protein in Retrograde Trafficking of L1-Type Cell Adhesion Molecule Neuroglian. Front Cell Neurosci 2019; 13:322. [PMID: 31354437 PMCID: PMC6640005 DOI: 10.3389/fncel.2019.00322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 07/01/2019] [Indexed: 11/21/2022] Open
Abstract
The role of the Amyloid Precursor Protein (APP) in the pathology of Alzheimer's disease (AD) has been well studied. However, the normal function of APP in the nervous system is poorly understood. Here, we characterized the role of the Drosophila homolog (APPL) in the adult giant fiber (GF) neurons. We find that endogenous APPL is transported from the synapse to the soma in the adult. Live-imaging revealed that retrograde moving APPL vesicles co-traffic with L1-type cell adhesion molecule Neuroglian (Nrg). In APPL null mutants, stationary Nrg vesicles were increased along the axon, and the number of Nrg vesicles moving in retrograde but not anterograde direction was reduced. In contrast, trafficking of endo-lysosomal vesicles, which did not co-localize with APPL in GF axons, was not affected. This suggests that APPL loss of function does not generally disrupt axonal transport but that APPL has a selective role in the effectiveness of retrograde transport of proteins it co-traffics with. While the GF terminals of APPL loss of function animals exhibited pruning defects, APPL gain of function had no disruptive effect on GF morphology and function, or on retrograde axonal transport of Nrg. However, cell-autonomous developmental expression of a secretion-deficient form of APPL (APPL-SD), lacking the α-, β-, and, γ-secretase cleavage sites, resulted in progressive retraction of the GF terminals. Conditional expression of APPL-SD in mature GFs caused accumulation of Nrg in normal sized synaptic terminals, which was associated with severely reduced retrograde flux of Nrg labeled vesicles in the axons. Albeit β-secretase null mutants developed GF terminals they also exhibited Nrg accumulations. This suggests that cleavage defective APPL has a toxic effect on retrograde trafficking and that β-secretase cleavage has a function in Nrg sorting in endosomal compartments at the synapse. In summary, our results suggest a role for APPL and its proteolytic cleavage sites in retrograde trafficking, thus our findings are of relevance to the understanding of the endogenous role of APP as well as to the development of therapeutic treatments of Alzheimer's disease.
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Mechanisms of Toxicity of Industrially Relevant Silicomanganese Dust on Human 1321N1 Astrocytoma Cells: An In Vitro Study. Int J Mol Sci 2019; 20:ijms20030740. [PMID: 30744184 PMCID: PMC6386893 DOI: 10.3390/ijms20030740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 01/27/2019] [Accepted: 02/02/2019] [Indexed: 12/19/2022] Open
Abstract
Tremendous efforts are applied in the ferroalloy industry to control and reduce exposure to dust generated during the production process, as inhalable Mn-containing particulate matter has been linked to neurodegenerative diseases. This study aimed to investigate the toxicity and biological effects of dust particles from laboratory-scale processes where molten silicomanganese (SiMn) was exposed to air, using a human astrocytoma cell line, 1321N1, as model system. Characterization of the dust indicated presence of both nano-sized and larger particles averaging between 100 and 300 nm. The dust consisted mainly of Si, Mn and O. Investigation of cellular mechanisms showed a dose- and time-dependent effect on cell viability, with only minor changes in the expression of proteins involved in apoptosis. Moreover, gene expression of the neurotoxic biomarker amyloid precursor protein (APP) increased, whereas APP protein expression decreased. Finally, induction of gap junctional intercellular communication (GJIC) increased with higher doses and correlated with the other endpoints. Thus, the effects of SiMn dust on 1321N1 cells are highly dependent on the dose of exposure and involves changes in APP, apoptosis-related proteins and intercellular communication.
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12
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Cellular Responses of Industrially Relevant Silica Dust on Human Glial Cells In Vitro. Int J Mol Sci 2019; 20:ijms20020358. [PMID: 30654492 PMCID: PMC6359019 DOI: 10.3390/ijms20020358] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 12/28/2018] [Accepted: 12/28/2018] [Indexed: 12/11/2022] Open
Abstract
Despite the rigorous emission control measures in the ferroalloy industry, there are still emissions of dust during the production of various alloys. Dust particles were collected from laboratory scale processes where oxide particulate matter was formed from liquid silicon (metallurgical grade). The dust was produced in a dry air atmosphere to mimic industrial conditions. To investigate possible effects of ultrafine dust on the central nervous system, a human astrocytic cell line was employed to investigate inflammatory effects of particles as astrocytes play a number of active and neuron supporting roles in the brain. Toxicity on the astrocytes by amorphous silica generated in laboratory scale was compared to crystalline macro-sized silica using several doses to determine toxicological dose response curves. The cell viability experiments indicated that low particle doses of amorphous silica induced a small nonsignificant reduction in cell viability compared to crystalline silica which led to increased levels of toxicity. The gene expression of amyloid precursor protein (APP), a biomarker of neurodegenerative disease, was affected by particle exposure. Furthermore, particle exposure, in a dose-and time-dependent manner, affected the ability of the cells to communicate through gap junction channels. In conclusion, in vitro studies using low doses of particles are important to understand mechanisms of toxicity of occupational exposure to silica particles. However, these studies cannot be extrapolated to real exposure scenarios at work place, therefore, controlling and keeping the particle exposure levels low at the work place, would prevent potential negative health effects.
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13
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Paolino G, Muscardin L, Didona D, Panetta C, Donati M, Mercuri SR, Donati P. Pigmented porokeratosis with dermal deposits of amyloid: the different chromatic features. GIORN ITAL DERMAT V 2018; 155:240-241. [PMID: 29998707 DOI: 10.23736/s0392-0488.18.05935-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Giovanni Paolino
- Department of Dermatology, Sapienza University, Rome, Italy.,Unit of Dermatology and Cosmetology, San Raffaele Hospital, Milan, Italy
| | - Luca Muscardin
- Laboratory of Dermatopathology, San Gallicano Institute of Rome, Rome, Italy
| | - Dario Didona
- Clinic of Dermatology and Allergology, University Clinic of Marburg, Marburg, Germany -
| | - Chiara Panetta
- Laboratory of Dermatopathology, San Gallicano Institute of Rome, Rome, Italy
| | - Michele Donati
- Department of Pathology, Campus Biomedico University, Rome, Italy
| | - Santo R Mercuri
- Unit of Dermatology and Cosmetology, San Raffaele Hospital, Milan, Italy
| | - Pietro Donati
- Laboratory of Dermatopathology, San Gallicano Institute of Rome, Rome, Italy
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14
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Fong LK, Yang MM, Dos Santos Chaves R, Reyna SM, Langness VF, Woodruff G, Roberts EA, Young JE, Goldstein LSB. Full-length amyloid precursor protein regulates lipoprotein metabolism and amyloid-β clearance in human astrocytes. J Biol Chem 2018; 293:11341-11357. [PMID: 29858247 DOI: 10.1074/jbc.ra117.000441] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 05/11/2018] [Indexed: 02/05/2023] Open
Abstract
Mounting evidence suggests that alterations in cholesterol homeostasis are involved in Alzheimer's disease (AD) pathogenesis. Amyloid precursor protein (APP) or multiple fragments generated by proteolytic processing of APP have previously been implicated in the regulation of cholesterol metabolism. However, the physiological function of APP in regulating lipoprotein homeostasis in astrocytes, which are responsible for de novo cholesterol biosynthesis and regulation in the brain, remains unclear. To address this, here we used CRISPR/Cas9 genome editing to generate isogenic APP-knockout (KO) human induced pluripotent stem cells (hiPSCs) and differentiated them into human astrocytes. We found that APP-KO astrocytes have reduced cholesterol and elevated levels of sterol regulatory element-binding protein (SREBP) target gene transcripts and proteins, which were both downstream consequences of reduced lipoprotein endocytosis. To elucidate which APP fragments regulate cholesterol homeostasis and to examine whether familial AD mutations in APP affect lipoprotein metabolism, we analyzed an isogenic allelic series harboring the APP Swedish and APP V717F variants. Only astrocytes homozygous for the APP Swedish (APPSwe/Swe) mutation, which had reduced full-length APP (FL APP) due to increased β-secretase cleavage, recapitulated the APP-KO phenotypes. Astrocytic internalization of β-amyloid (Aβ), another ligand for low-density lipoprotein (LDL) receptors, was also impaired in APP-KO and APPSwe/Swe astrocytes. Finally, impairing cleavage of FL APP through β-secretase inhibition in APPSwe/Swe astrocytes reversed the LDL and Aβ endocytosis defects. In conclusion, FL APP is involved in the endocytosis of LDL receptor ligands and is required for proper cholesterol homeostasis and Aβ clearance in human astrocytes.
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Affiliation(s)
- Lauren K Fong
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093; Sanford Consortium for Regenerative Medicine, La Jolla, California 92093
| | - Max M Yang
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093; Sanford Consortium for Regenerative Medicine, La Jolla, California 92093
| | - Rodrigo Dos Santos Chaves
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093; Sanford Consortium for Regenerative Medicine, La Jolla, California 92093
| | - Sol M Reyna
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093; Sanford Consortium for Regenerative Medicine, La Jolla, California 92093
| | - Vanessa F Langness
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093; Sanford Consortium for Regenerative Medicine, La Jolla, California 92093
| | - Grace Woodruff
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093; Sanford Consortium for Regenerative Medicine, La Jolla, California 92093
| | - Elizabeth A Roberts
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093; Sanford Consortium for Regenerative Medicine, La Jolla, California 92093
| | - Jessica E Young
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093; Department of Pathology and Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington 98195
| | - Lawrence S B Goldstein
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093; Sanford Consortium for Regenerative Medicine, La Jolla, California 92093; Department of Neurosciences, University of California at San Diego, La Jolla, California 92093.
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15
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Otero MG, Bessone IF, Hallberg AE, Cromberg LE, De Rossi MC, Saez TM, Levi V, Almenar-Queralt A, Falzone TL. Proteasome stress leads to APP axonal transport defects by promoting its amyloidogenic processing in lysosomes. J Cell Sci 2018; 131:jcs.214536. [DOI: 10.1242/jcs.214536] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Accepted: 04/25/2018] [Indexed: 01/25/2023] Open
Abstract
Alzheimer Disease (AD) pathology includes the accumulation of poly-ubiquitinated proteins and failures in proteasome-dependent degradation. Whereas the distribution of proteasomes and its role in synaptic function have been studied, whether proteasome activity regulates the axonal transport and metabolism of the amyloid precursor protein (APP), remains elusive. Using live imaging in primary hippocampal neurons, we showed that proteasome inhibition rapidly and severely impairs the axonal transport of APP. Fluorescent cross-correlation analyses and membrane internalization blockage showed that plasma membrane APP do not contribute to transport defects. Moreover, by western blots and double-color APP imaging we demonstrated that proteasome inhibition precludes APP axonal transport by enhancing its endo-lysosomal delivery where β-cleavage is induced. Together, we found that proteasomes controls the distal transport of APP and can re-distribute Golgi-derived vesicles to the endo-lysosomal pathway. This crosstalk between proteasomes and lysosomes regulates APP intracellular dynamics, and defects in proteasome activity can be considered a contributing factor that lead to abnormal APP metabolism in AD.
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Affiliation(s)
- María Gabriela Otero
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
| | - Ivan Fernandez Bessone
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
| | - Alan Earle Hallberg
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
| | - Lucas Eneas Cromberg
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
| | - María Cecilia De Rossi
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica-IQUIBICEN UBA-CONICET, CP1428EGA, Argentina
| | - Trinidad M. Saez
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
- Instituto de Biología y Medicina Experimental, IBYME (CONICET). Vuelta de obligado 2490, Buenos Aires, CP 1428, Argentina
| | - Valeria Levi
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica-IQUIBICEN UBA-CONICET, CP1428EGA, Argentina
| | - Angels Almenar-Queralt
- Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Tomás Luis Falzone
- Instituto de Biología Celular y Neurociencias, IBCN (CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires. Paraguay 2155, Buenos Aires, CP1121, Argentina
- Instituto de Biología y Medicina Experimental, IBYME (CONICET). Vuelta de obligado 2490, Buenos Aires, CP 1428, Argentina
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16
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Iacobucci GJ, Gunawardena S. Ethanol stimulates the in vivo axonal movement of neuropeptide dense-core vesicles in Drosophila motor neurons. J Neurochem 2017; 144:466-482. [PMID: 28960313 DOI: 10.1111/jnc.14230] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 09/10/2017] [Accepted: 09/18/2017] [Indexed: 01/01/2023]
Abstract
Proper neuronal function requires essential biological cargoes to be packaged within membranous vesicles and transported, intracellularly, through the extensive outgrowth of axonal and dendritic fibers. The precise spatiotemporal movement of these cargoes is vital for neuronal survival and, thus, is highly regulated. In this study we test how the axonal movement of a neuropeptide-containing dense-core vesicle (DCV) responds to alcohol stressors. We found that ethanol induces a strong anterograde bias in vesicle movement. Low doses of ethanol stimulate the anterograde movement of neuropeptide-DCV while high doses inhibit bi-directional movement. This process required the presence of functional kinesin-1 motors as reduction in kinesin prevented the ethanol-induced stimulation of the anterograde movement of neuropeptide-DCV. Furthermore, expression of inactive glycogen synthase kinase 3 (GSK-3β) also prevented ethanol-induced stimulation of neuropeptide-DCV movement, similar to pharmacological inhibition of GSK-3β with lithium. Conversely, inhibition of PI3K/AKT signaling with wortmannin led to a partial prevention of ethanol-stimulated transport of neuropeptide-DCV. Taken together, we conclude that GSK-3β signaling mediates the stimulatory effects of ethanol. Therefore, our study provides new insight into the physiological response of the axonal movement of neuropeptide-DCV to exogenous stressors. Cover Image for this Issue: doi: 10.1111/jnc.14165.
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Affiliation(s)
- Gary J Iacobucci
- Department of Biological Sciences, the State University of New York at Buffalo, Buffalo, New York, USA
| | - Shermali Gunawardena
- Department of Biological Sciences, the State University of New York at Buffalo, Buffalo, New York, USA
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17
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Gan KJ, Silverman MA. Imaging organelle transport in primary hippocampal neurons treated with amyloid-β oligomers. Methods Cell Biol 2015; 131:425-51. [PMID: 26794527 DOI: 10.1016/bs.mcb.2015.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We describe a strategy for fluorescent imaging of organelle transport in primary hippocampal neurons treated with amyloid-β (Aβ) peptides that cause Alzheimer's disease (AD). This method enables careful, rigorous analyses of axonal transport defects, which are implicated in AD and other neurodegenerative diseases. Moreover, we present and emphasize guidelines for investigating Aβ-induced mechanisms of axonal transport disruption in the absence of nonspecific, irreversible cellular toxicity. This approach should be accessible to most laboratories equipped with cell culture facilities and a standard fluorescent microscope and may be adapted to other cell types.
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Affiliation(s)
- Kathlyn J Gan
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Michael A Silverman
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada; Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada; Brain Research Centre, University of British Columbia, Vancouver, BC, Canada
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18
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Tong Y, Sun Y, Tian X, Zhou T, Wang H, Zhang T, Zhan R, Zhao L, Kuerban B, Li Z, Wang Q, Jin Y, Fan D, Guo X, Han H, Qin S, Chui D. Phospholipid transfer protein (PLTP) deficiency accelerates memory dysfunction through altering amyloid precursor protein (APP) processing in a mouse model of Alzheimer's disease. Hum Mol Genet 2015; 24:5388-403. [DOI: 10.1093/hmg/ddv262] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 07/06/2015] [Indexed: 01/19/2023] Open
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19
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van der Kant R, Goldstein LSB. Cellular functions of the amyloid precursor protein from development to dementia. Dev Cell 2015; 32:502-15. [PMID: 25710536 DOI: 10.1016/j.devcel.2015.01.022] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Amyloid precursor protein (APP) is a key player in Alzheimer's disease (AD). The Aβ fragments of APP are the major constituent of AD-associated amyloid plaques, and mutations or duplications of the gene coding for APP can cause familial AD. Here we review the roles of APP in neuronal development, signaling, intracellular transport, and other aspects of neuronal homeostasis. We suggest that APP acts as a signaling nexus that transduces information about a range of extracellular conditions, including neuronal damage, to induction of intracellular signaling events. Subtle disruptions of APP signaling functions may be major contributors to AD-causing neuronal dysfunction.
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Affiliation(s)
- Rik van der Kant
- Department of Cellular and Molecular Medicine, University of California-San Diego, La Jolla, CA 92093, USA.
| | - Lawrence S B Goldstein
- Department of Cellular and Molecular Medicine, University of California-San Diego, La Jolla, CA 92093, USA.
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20
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Fe65 Ser228 is phosphorylated by ATM/ATR and inhibits Fe65-APP-mediated gene transcription. Biochem J 2015; 465:413-21. [PMID: 25397632 DOI: 10.1042/bj20140656] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Fe65 binds the amyloid precursor protein (APP) and regulates the secretase-mediated processing of APP into several proteolytic fragments, including amyloid β-peptides (Aβ) and APP intracellular domain (AICD). Aβ accumulation in neural plaques is a pathological feature of Alzheimer's disease (AD) and AICD has important roles in the regulation of gene transcription (in complex with Fe65). It is therefore important to understand how Fe65 is regulated and how this contributes to the function and/or processing of APP. Studies have also implicated Fe65 in the cellular DNA damage response with knockout mice showing increased DNA strand breaks and Fe65 demonstrating a gel mobility shift after DNA damage, consistent with protein phosphorylation. In the present study, we identified Fe65 Ser(228) as a novel target of the ATM (ataxia telangiectasia mutated) and ATR (ataxia-telangiectasia- and Rad3-related protein) protein kinases, in a reaction that occurred independently of APP. Neither phosphorylation nor mutation of Ser(228) affected the Fe65-APP complex, though this was markedly decreased after UV treatment, with a concomitant decrease in the protein levels of APP in cells. Finally, mutation of Ser(228) to alanine (thus blocking phosphorylation) caused a significant increase in Fe65-APP transcriptional activity, whereas phosphomimetic mutants (S(228)D and S(228)E) showed decreased transcriptional activity. These studies identify a novel phosphorylation site within Fe65 and a novel regulatory mechanism for the transcriptional activity of the Fe65-APP complex.
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21
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Chauvin S, Sobel A. Neuronal stathmins: A family of phosphoproteins cooperating for neuronal development, plasticity and regeneration. Prog Neurobiol 2015; 126:1-18. [DOI: 10.1016/j.pneurobio.2014.09.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 09/23/2014] [Accepted: 09/29/2014] [Indexed: 02/06/2023]
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22
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Takei N, Sobu Y, Kimura A, Urano S, Piao Y, Araki Y, Taru H, Yamamoto T, Hata S, Nakaya T, Suzuki T. Cytoplasmic fragment of Alcadein α generated by regulated intramembrane proteolysis enhances amyloid β-protein precursor (APP) transport into the late secretory pathway and facilitates APP cleavage. J Biol Chem 2014; 290:987-95. [PMID: 25406318 DOI: 10.1074/jbc.m114.599852] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The neural type I membrane protein Alcadein α (Alcα), is primarily cleaved by amyloid β-protein precursor (APP) α-secretase to generate a membrane-associated carboxyl-terminal fragment (Alcα CTF), which is further cleaved by γ-secretase to secrete p3-Alcα peptides and generate an intracellular cytoplasmic domain fragment (Alcα ICD) in the late secretory pathway. By association with the neural adaptor protein X11L (X11-like), Alcα and APP form a ternary complex that suppresses the cleavage of both Alcα and APP by regulating the transport of these membrane proteins into the late secretory pathway where secretases are active. However, it has not been revealed how Alcα and APP are directed from the ternary complex formed largely in the Golgi into the late secretory pathway to reach a nerve terminus. Using a novel transgenic mouse line expressing excess amounts of human Alcα CTF (hAlcα CTF) in neurons, we found that expression of hAlcα CTF induced excess production of hAlcα ICD, which facilitated APP transport into the nerve terminus and enhanced APP metabolism, including Aβ generation. In vitro cell studies also demonstrated that excess expression of Alcα ICD released both APP and Alcα from the ternary complex. These results indicate that regulated intramembrane proteolysis of Alcα by γ-secretase regulates APP trafficking and the production of Aβ in vivo.
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Affiliation(s)
- Norio Takei
- From the Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan and
| | - Yuriko Sobu
- From the Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan and
| | - Ayano Kimura
- From the Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan and
| | - Satomi Urano
- From the Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan and
| | - Yi Piao
- From the Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan and
| | - Yoichi Araki
- From the Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan and
| | - Hidenori Taru
- From the Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan and
| | - Tohru Yamamoto
- Department of Molecular Neurobiology, Faculty of Medicine, Kagawa University, Miki-cho 761-0793, Japan
| | - Saori Hata
- From the Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan and
| | - Tadashi Nakaya
- From the Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan and
| | - Toshiharu Suzuki
- From the Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan and
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23
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Abstract
Vesicles, organelles and other intracellular cargo are transported by kinesin and dynein motors, which move in opposite directions along microtubules. This bidirectional cargo movement is frequently described as a 'tug of war' between oppositely directed molecular motors attached to the same cargo. However, although many experimental and modelling studies support the tug-of-war paradigm, numerous knockout and inhibition studies in various systems have found that inhibiting one motor leads to diminished motility in both directions, which is a 'paradox of co-dependence' that challenges the paradigm. In an effort to resolve this paradox, three classes of bidirectional transport models--microtubule tethering, mechanical activation and steric disinhibition--are proposed, and a general mathematical modelling framework for bidirectional cargo transport is put forward to guide future experiments.
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