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De Mena L, Smith MA, Martin J, Dunton KL, Ceballos-Diaz C, Jansen-West KR, Cruz PE, Dillon KD, Rincon-Limas DE, Golde TE, Moore BD, Levites Y. Aß40 displays amyloidogenic properties in the non-transgenic mouse brain but does not exacerbate Aß42 toxicity in Drosophila. Alzheimers Res Ther 2020; 12:132. [PMID: 33069251 PMCID: PMC7568834 DOI: 10.1186/s13195-020-00698-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/29/2020] [Indexed: 11/17/2022]
Abstract
BACKGROUND Self-assembly of the amyloid-β (Aβ) peptide into aggregates, from small oligomers to amyloid fibrils, is fundamentally linked with Alzheimer's disease (AD). However, it is clear that not all forms of Aβ are equally harmful and that linking a specific aggregate to toxicity also depends on the assays and model systems used (Haass et al., J Biol. Chem 269:17741-17748, 1994; Borchelt et al., Neuron 17:1005-1013, 1996). Though a central postulate of the amyloid cascade hypothesis, there remain many gaps in our understanding regarding the links between Aβ deposition and neurodegeneration. METHODS In this study, we examined familial mutations of Aβ that increase aggregation and oligomerization, E22G and ΔE22, and induce cerebral amyloid angiopathy, E22Q and D23N. We also investigated synthetic mutations that stabilize dimerization, S26C, and a phospho-mimetic, S8E, and non-phospho-mimetic, S8A. To that end, we utilized BRI2-Aβ fusion technology and rAAV2/1-based somatic brain transgenesis in mice to selectively express individual mutant Aβ species in vivo. In parallel, we generated PhiC31-based transgenic Drosophila melanogaster expressing wild-type (WT) and Aβ40 and Aβ42 mutants, fused to the Argos signal peptide to assess the extent of Aβ42-induced toxicity as well as to interrogate the combined effect of different Aβ40 and Aβ42 species. RESULTS When expressed in the mouse brain for 6 months, Aβ42 E22G, Aβ42 E22Q/D23N, and Aβ42WT formed amyloid aggregates consisting of some diffuse material as well as cored plaques, whereas other mutants formed predominantly diffuse amyloid deposits. Moreover, while Aβ40WT showed no distinctive phenotype, Aβ40 E22G and E22Q/D23N formed unique aggregates that accumulated in mouse brains. This is the first evidence that mutant Aβ40 overexpression leads to deposition under certain conditions. Interestingly, we found that mutant Aβ42 E22G, E22Q, and S26C, but not Aβ40, were toxic to the eye of Drosophila. In contrast, flies expressing a copy of Aβ40 (WT or mutants), in addition to Aβ42WT, showed improved phenotypes, suggesting possible protective qualities for Aβ40. CONCLUSIONS These studies suggest that while some Aβ40 mutants form unique amyloid aggregates in mouse brains, they do not exacerbate Aβ42 toxicity in Drosophila, which highlights the significance of using different systems for a better understanding of AD pathogenicity and more accurate screening for new potential therapies.
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Affiliation(s)
- Lorena De Mena
- Department of Neurology, McKnight Brain Institute, University of Florida and Norman Fixel Institute for Neurological Diseases, Gainesville, FL, USA
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Michael A Smith
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Jason Martin
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Katie L Dunton
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Carolina Ceballos-Diaz
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | | | - Pedro E Cruz
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Kristy D Dillon
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Diego E Rincon-Limas
- Department of Neurology, McKnight Brain Institute, University of Florida and Norman Fixel Institute for Neurological Diseases, Gainesville, FL, USA
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Todd E Golde
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Brenda D Moore
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA.
| | - Yona Levites
- Center for Translational Research in Neurodegenerative Disease and Department of Neuroscience, Gainesville, FL, USA.
- McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA.
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Chandran JS, Scarrott JM, Shaw PJ, Azzouz M. Gene Therapy in the Nervous System: Failures and Successes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1007:241-257. [PMID: 28840561 DOI: 10.1007/978-3-319-60733-7_13] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Genetic disorders, caused by deleterious changes in the DNA sequence away from the normal genomic sequence, affect millions of people worldwide. Gene therapy as a treatment option for patients is an attractive proposition due to its conceptual simplicity. In principle, gene therapy involves correcting the genetic disorder by either restoring a normal functioning copy of a gene or reducing the toxicity arising from a mutated gene. In this way specific genetic function can be restored without altering the expression of other genes and the proteins they encode. The reality however is much more complex, and as a result the vector systems used to deliver gene therapies have by necessity continued to evolve and improve over time with respect to safety profile, efficiency, and long-term expression. In this chapter we examine the current approaches to gene therapy, assess the different gene delivery systems utilized, and highlight the failures and successes of relevant clinical trials. We do not intend for this chapter to be a comprehensive and exhaustive assessment of all clinical trials that have been conducted in the CNS, but instead will focus on specific diseases that have seen successes and failures with different gene therapy vehicles to gauge how preclinical models have informed the design of clinical trials.
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Affiliation(s)
- Jayanth S Chandran
- Sheffield Institute for Translational Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
| | - Joseph M Scarrott
- Sheffield Institute for Translational Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
| | - Pamela J Shaw
- Sheffield Institute for Translational Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
| | - Mimoun Azzouz
- Sheffield Institute for Translational Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK.
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Chan AWS. Transgenic nonhuman primates for neurodegenerative diseases. Reprod Biol Endocrinol 2004; 2:39. [PMID: 15200672 PMCID: PMC441412 DOI: 10.1186/1477-7827-2-39] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Accepted: 06/16/2004] [Indexed: 01/08/2023] Open
Abstract
Animal models that represent human diseases constitute an important tool in understanding the pathogenesis of the diseases, and in developing effective therapies. Neurodegenerative diseases are complex disorders involving neuropathologic and psychiatric alterations. Although transgenic and knock-in mouse models of Alzheimer's disease, (AD), Parkinson's disease (PD) and Huntington's disease (HD) have been created, limited representation in clinical aspects has been recognized and the rodent models lack true neurodegeneration. Chemical induction of HD and PD in nonhuman primates (NHP) has been reported, however, the role of intrinsic genetic factors in the development of the diseases is indeterminable. Nonhuman primates closely parallel humans with regard to genetic, neuroanatomic, and cognitive/behavioral characteristics. Accordingly, the development of NHP models for neurodegenerative diseases holds greater promise for success in the discovery of diagnoses, treatments, and cures than approaches using other animal species. Therefore, a transgenic NHP carrying a mutant gene similar to that of patients will help to clarify our understanding of disease onset and progression. Additionally, monitoring disease onset and development in the transgenic NHP by high resolution brain imaging technology such as MRI, and behavioral and cognitive testing can all be carried out simultaneously in the NHP but not in other animal models. Moreover, because of the similarity in motor repertoire between NHPs and humans, it will also be possible to compare the neurologic syndrome observed in the NHP model to that in patients. Understanding the correlation between genetic defects and physiologic changes (e.g. oxidative damage) will lead to a better understanding of disease progression and the development of patient treatments, medications and preventive approaches for high risk individuals. The impact of the transgenic NHP model in understanding the role which genetic disorders play in the development of efficacious interventions and medications is foreseeable.
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Affiliation(s)
- Anthony W S Chan
- Yerkes National Primate Research Center and Department of Human Genetics, Emory University, Atlanta, Georgia, USA.
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Park L, Anrather J, Forster C, Kazama K, Carlson GA, Iadecola C. Abeta-induced vascular oxidative stress and attenuation of functional hyperemia in mouse somatosensory cortex. J Cereb Blood Flow Metab 2004; 24:334-42. [PMID: 15091114 DOI: 10.1097/01.wcb.0000105800.49957.1e] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We investigated the role of vascular oxidative stress in the mechanisms of the impairment in cerebrovascular regulation produced by the amyloid-beta peptide (Abeta). In particular, we sought to provide evidence of vascular oxidative stress in mice overexpressing the amyloid precursor protein (APP) and to determine whether the Abeta-induced attenuation in functional hyperemia is mediated by free radical overproduction. Oxidative/nitrosative stress was assessed by 3-nitrotyrosine immunoreactivity, while free radical production was determined in cerebral microvessels by hydroethidine microfluorography. To study functional hyperemia the somatosensory cortex was activated by whisker stimulation while local blood flow was monitored by laser-Doppler flowmetry. It was found that APP mice show signs of oxidative/nitrosative stress in pial and intracerebral blood vessels well before they develop oxidative stress in neurons and glia or amyloid plaques. Treatment of cerebral microvessels isolated from wild-type mice with Abeta (1 microM) increased free radical production as assessed by the hydroethidine technique. The Abeta-induced attenuation of the increase in somatosensory cortex blood flow produced by whisker stimulation was prevented by treatment with the free radical scavengers MnTBAP or tiron. These data provide evidence that in APP mice vascular oxidative stress precedes the development of parenchymal oxidative stress, and that Abeta-produced vascular reactive oxygen species are involved in the attendant attenuation in functional hyperemia. Thus, vascular oxidative stress is an early event in the course of the brain dysfunction produced by APP overexpression and Abeta, and, as such, could be the target of early therapeutic interventions based on antioxidants.
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Affiliation(s)
- Laibaik Park
- Division of Neurobiology, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, New York 10021, USA
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Abstract
There is growing evidence that reduced neurotrophic support is a significant factor in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS). In this review we discuss the structure and functions of neurotrophins such as nerve growth factor, and the role of these proteins and their tyrosine kinase (Trk) receptors in the aetiology and therapy of such diseases. Neurotrophins regulate development and the maintenance of the vertebrate nervous system. In the mature nervous system they affect neuronal survival and also influence synaptic function and plasticity. The neurotrophins are able to bind to two different receptors: all bind to a common receptor p75NTR, and each also binds to one of a family of Trk receptors. By dimerization of the Trk receptors, and subsequent transphosphorylation of the intracellular kinase domain, signalling pathways are activated. We discuss here the structure and function of the neurotrophins and how they have been, or may be, used therapeutically in AD, PD, Huntington's diseases, ALS and peripheral neuropathy. Neurotrophins are central to many aspects of nervous system function. However they have not truly fulfilled their therapeutic potential in clinical trials because of the difficulties of protein delivery and pharmacokinetics in the nervous system. With the recent elucidation of the structure of the neurotrophins bound to their receptors it will now be possible, using a combination of in silico technology and novel screening techniques, to develop small molecule mimetics with much improved pharmacotherapeutic profiles.
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Affiliation(s)
- D Dawbarn
- University of Bristol, Bristol Royal Infirmary, Bristol, UK.
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