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Rezaee N, Fernando WB, Hone E, Sohrabi HR, Johnson SK, Gunzburg S, Martins RN. Potential of Sorghum Polyphenols to Prevent and Treat Alzheimer's Disease: A Review Article. Front Aging Neurosci 2021; 13:729949. [PMID: 34690742 PMCID: PMC8527926 DOI: 10.3389/fnagi.2021.729949] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 08/24/2021] [Indexed: 12/06/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by the excessive deposition of extracellular amyloid-beta peptide (Aβ) and the build-up of intracellular neurofibrillary tangles containing hyperphosphorylated tau proteins. This leads to neuronal damage, cell death and consequently results in memory and learning impairments leading to dementia. Although the exact cause of AD is not yet clear, numerous studies indicate that oxidative stress, inflammation, and mitochondrial dysfunction significantly contribute to its onset and progression. There is no effective therapeutic approach to stop the progression of AD and its associated symptoms. Thus, early intervention, preferably, pre-clinically when the brain is not significantly affected, is a better option for effective treatment. Natural polyphenols (PP) target multiple AD-related pathways such as protecting the brain from Aβ and tau neurotoxicity, ameliorating oxidative damage and mitochondrial dysfunction. Among natural products, the cereal crop sorghum has some unique features. It is one of the major global grain crops but in the developed world, it is primarily used as feed for farm animals. A broad range of PP, including phenolic acids, flavonoids, and condensed tannins are present in sorghum grain including some classes such as proanthocyanidins that are rarely found in others plants. Pigmented varieties of sorghum have the highest polyphenolic content and antioxidant activity which potentially makes their consumption beneficial for human health through different pathways such as oxidative stress reduction and thus the prevention and treatment of neurodegenerative diseases. This review summarizes the potential of sorghum PP to beneficially affect the neuropathology of AD.
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Affiliation(s)
- Nasim Rezaee
- Centre of Excellence for Alzheimer’s Disease Research & Care, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - W.M.A.D. Binosha Fernando
- Centre of Excellence for Alzheimer’s Disease Research & Care, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Eugene Hone
- Centre of Excellence for Alzheimer’s Disease Research & Care, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Hamid R. Sohrabi
- Centre of Excellence for Alzheimer’s Disease Research & Care, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
- Department of Biomedical Sciences, Macquarie University, Sydney, NSW, Australia
- Centre for Healthy Ageing, Health Future Institute, Murdoch University, Murdoch, WA, Australia
| | - Stuart K. Johnson
- School of Molecular and Life Sciences, Faculty of Science and Engineering, Curtin University, Perth, WA, Australia
- Ingredients by Design Pty Ltd., Lesmurdie, WA, Australia
| | | | - Ralph N. Martins
- Centre of Excellence for Alzheimer’s Disease Research & Care, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
- Department of Biomedical Sciences, Macquarie University, Sydney, NSW, Australia
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Ntsapi C, Lumkwana D, Swart C, du Toit A, Loos B. New Insights Into Autophagy Dysfunction Related to Amyloid Beta Toxicity and Neuropathology in Alzheimer's Disease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 336:321-361. [DOI: 10.1016/bs.ircmb.2017.07.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Intracellular Calcium Dysregulation: Implications for Alzheimer's Disease. BIOMED RESEARCH INTERNATIONAL 2016; 2016:6701324. [PMID: 27340665 PMCID: PMC4909906 DOI: 10.1155/2016/6701324] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/15/2016] [Indexed: 12/31/2022]
Abstract
Alzheimer's Disease (AD) is a neurodegenerative disorder characterized by progressive neuronal loss. AD is associated with aberrant processing of the amyloid precursor protein, which leads to the deposition of amyloid-β plaques within the brain. Together with plaques deposition, the hyperphosphorylation of the microtubules associated protein tau and the formation of intraneuronal neurofibrillary tangles are a typical neuropathological feature in AD brains. Cellular dysfunctions involving specific subcellular compartments, such as mitochondria and endoplasmic reticulum (ER), are emerging as crucial players in the pathogenesis of AD, as well as increased oxidative stress and dysregulation of calcium homeostasis. Specifically, dysregulation of intracellular calcium homeostasis has been suggested as a common proximal cause of neural dysfunction in AD. Aberrant calcium signaling has been considered a phenomenon mainly related to the dysfunction of intracellular calcium stores, which can occur in both neuronal and nonneuronal cells. This review reports the most recent findings on cellular mechanisms involved in the pathogenesis of AD, with main focus on the control of calcium homeostasis at both cytosolic and mitochondrial level.
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Zheng K, Dai X, Xiao N, Wu X, Wei Z, Fang W, Zhu Y, Zhang J, Chen X. Curcumin Ameliorates Memory Decline via Inhibiting BACE1 Expression and β-Amyloid Pathology in 5×FAD Transgenic Mice. Mol Neurobiol 2016; 54:1967-1977. [PMID: 26910813 DOI: 10.1007/s12035-016-9802-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 02/16/2016] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is the most common dementia and the trigger of its pathological cascade is widely believed to be the overproduction and accumulation of β-amyloid protein (Aβ) in the affected brain. However, effective AD remedies are still anxiously awaited. Recent evidence suggests that curcumin may be a potential agent for AD treatment. In this study, we used 5×FAD transgenic mice as an AD model to investigate the effects of curcumin on AD. Our results showed that curcumin administration (150 or 300 mg/kg/day, intragastrically, for 60 days) dramatically reduced Aβ production by downregulating BACE1 expression, preventing synaptic degradation, and improving spatial learning and memory impairment of 5×FAD mice. These findings suggest that curcumin is a potential candidate for AD treatment.
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Affiliation(s)
- Kunmu Zheng
- Department of Neurology and Geriatrics, Fujian Institute of Geriatrics, Affiliated Union Hospital of Fujian Medical University, 29 Xinquan Road, Fuzhou, Fujian, 350001, People's Republic of China.,Key Laboratory of Brain Aging and Neurodegenerative Diseases, Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, 29 Xinquan Road, Fuzhou, 350001, China.,Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, 361000, China
| | - Xiaoman Dai
- Department of Neurology and Geriatrics, Fujian Institute of Geriatrics, Affiliated Union Hospital of Fujian Medical University, 29 Xinquan Road, Fuzhou, Fujian, 350001, People's Republic of China.,Key Laboratory of Brain Aging and Neurodegenerative Diseases, Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, 29 Xinquan Road, Fuzhou, 350001, China
| | - Nai'an Xiao
- Key Laboratory of Brain Aging and Neurodegenerative Diseases, Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, 29 Xinquan Road, Fuzhou, 350001, China.,Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, 361000, China
| | - Xilin Wu
- Key Laboratory of Brain Aging and Neurodegenerative Diseases, Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, 29 Xinquan Road, Fuzhou, 350001, China
| | - Zhen Wei
- Key Laboratory of Brain Aging and Neurodegenerative Diseases, Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, 29 Xinquan Road, Fuzhou, 350001, China
| | - Wenting Fang
- Key Laboratory of Brain Aging and Neurodegenerative Diseases, Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, 29 Xinquan Road, Fuzhou, 350001, China
| | - Yuangui Zhu
- Department of Neurology and Geriatrics, Fujian Institute of Geriatrics, Affiliated Union Hospital of Fujian Medical University, 29 Xinquan Road, Fuzhou, Fujian, 350001, People's Republic of China.,Key Laboratory of Brain Aging and Neurodegenerative Diseases, Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, 29 Xinquan Road, Fuzhou, 350001, China
| | - Jing Zhang
- Department of Neurology and Geriatrics, Fujian Institute of Geriatrics, Affiliated Union Hospital of Fujian Medical University, 29 Xinquan Road, Fuzhou, Fujian, 350001, People's Republic of China. .,Key Laboratory of Brain Aging and Neurodegenerative Diseases, Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, 29 Xinquan Road, Fuzhou, 350001, China.
| | - Xiaochun Chen
- Department of Neurology and Geriatrics, Fujian Institute of Geriatrics, Affiliated Union Hospital of Fujian Medical University, 29 Xinquan Road, Fuzhou, Fujian, 350001, People's Republic of China. .,Key Laboratory of Brain Aging and Neurodegenerative Diseases, Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, 29 Xinquan Road, Fuzhou, 350001, China.
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Sun X, Chen WD, Wang YD. β-Amyloid: the key peptide in the pathogenesis of Alzheimer's disease. Front Pharmacol 2015; 6:221. [PMID: 26483691 PMCID: PMC4588032 DOI: 10.3389/fphar.2015.00221] [Citation(s) in RCA: 187] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 09/17/2015] [Indexed: 12/20/2022] Open
Abstract
The amyloid β peptide (Aβ) is a critical initiator that triggers the progression of Alzheimer's Disease (AD) via accumulation and aggregation, of which the process may be caused by Aβ overproduction or perturbation clearance. Aβ is generated from amyloid precursor protein through sequential cleavage of β- and γ-secretases while Aβ removal is dependent on the proteolysis and lysosome degradation system. Here, we overviewed the biogenesis and toxicity of Aβ as well as the regulation of Aβ production and clearance. Moreover, we also summarized the animal models correlated with Aβ that are essential in AD research. In addition, we discussed current immunotherapeutic approaches targeting Aβ to give some clues for exploring the more potentially efficient drugs for treatment of AD.
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Affiliation(s)
- Xiaojuan Sun
- Key Laboratory of Receptors-Mediated Gene Regulation and Drug Discovery, School of Medicine, Henan University Kaifeng, China
| | - Wei-Dong Chen
- Key Laboratory of Receptors-Mediated Gene Regulation and Drug Discovery, School of Medicine, Henan University Kaifeng, China
| | - Yan-Dong Wang
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology Beijing, China
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Vorobyeva AG, Lee R, Miller S, Longen C, Sharoni M, Kandelwal PJ, Kim FJ, Marenda DR, Saunders AJ. Cyclopamine modulates γ-secretase-mediated cleavage of amyloid precursor protein by altering its subcellular trafficking and lysosomal degradation. J Biol Chem 2014; 289:33258-74. [PMID: 25281744 DOI: 10.1074/jbc.m114.591792] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Alzheimer disease (AD) is a progressive neurodegenerative disease leading to memory loss. Numerous lines of evidence suggest that amyloid-β (Aβ), a neurotoxic peptide, initiates a cascade that results in synaptic dysfunction, neuronal death, and eventually cognitive deficits. Aβ is generated by the proteolytic processing of the amyloid precursor protein (APP), and alterations to this processing can result in Alzheimer disease. Using in vitro and in vivo models, we identified cyclopamine as a novel regulator of γ-secretase-mediated cleavage of APP. We demonstrate that cyclopamine decreases Aβ generation by altering APP retrograde trafficking. Specifically, cyclopamine treatment reduced APP-C-terminal fragment (CTF) delivery to the trans-Golgi network where γ-secretase cleavage occurs. Instead, cyclopamine redirects APP-CTFs to the lysosome. These data demonstrate that cyclopamine treatment decreases γ-secretase-mediated cleavage of APP. In addition, cyclopamine treatment decreases the rate of APP-CTF degradation. Together, our data demonstrate that cyclopamine alters APP processing and Aβ generation by inducing changes in APP subcellular trafficking and APP-CTF degradation.
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Affiliation(s)
- Anna G Vorobyeva
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and
| | - Randall Lee
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and
| | - Sean Miller
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and
| | | | - Michal Sharoni
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and
| | - Preeti J Kandelwal
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and
| | - Felix J Kim
- the Departments of Pharmacology and Physiology
| | - Daniel R Marenda
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and Neurobiology and Anatomy, and
| | - Aleister J Saunders
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and Neurobiology and Anatomy, and Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102
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Henriques AG, Oliveira JM, Gomes B, Ruivo R, da Cruz e Silva EF, da Cruz e Silva OAB. Complexing Aβ prevents the cellular anomalies induced by the Peptide alone. J Mol Neurosci 2014; 53:661-8. [PMID: 24599756 PMCID: PMC4112052 DOI: 10.1007/s12031-014-0233-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/10/2014] [Indexed: 12/01/2022]
Abstract
Retention of intracellular secreted APP (isAPP) can be provoked by the neurotoxic peptide Aβ. The latter decreases in the cerebrospinal fluid of Alzheimer’s disease (AD) patients, as a consequence of its cerebral accumulation and deposition into senile plaques. Of similar relevance, secreted APP (sAPP) levels can be associated with AD. The studies here presented, reinforce the link between sAPP and Aβ and address putative therapeutic strategies. Laminin and gelsolin are potential candidates; both prevent Aβ fibril formation by complexing with Aβ, thus attenuating its neurotoxicity. We show that preincubation of Aβ with laminin and gelsolin has the effect of rendering it less potent to isAPP accumulation in cortical neurons. This appears to be related to a decrease in F-actin polymerization, whereas Aβ alone induces the polymerization. Further, Aβ decreases gelsolin levels, and the latter is involved in Aβ removal. Our data indicates that Aβ-laminin and Aβ-gelsolin complexes are less neurotoxic and also less potent than fibrillar Aβ at inducing isAPP retention. These results validate the potential of these proteins as therapeutic strategies that prevent the Aβ-induced effects. In hence, given that Aβ decreases the levels of proteins involved in its own clearance, this may contribute to the mechanisms underlying AD pathology.
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Affiliation(s)
- A. G. Henriques
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - J. M. Oliveira
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - B. Gomes
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - R. Ruivo
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - E. F. da Cruz e Silva
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - O. A. B. da Cruz e Silva
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
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Woods NK, Padmanabhan J. Inhibition of amyloid precursor protein processing enhances gemcitabine-mediated cytotoxicity in pancreatic cancer cells. J Biol Chem 2013; 288:30114-30124. [PMID: 24022491 DOI: 10.1074/jbc.m113.459255] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pancreatic adenocarcinoma or pancreatic cancer is often diagnosed at a very late stage at which point treatment options are minimal. Current chemotherapeutic interventions prolong survival marginally, thereby emphasizing the acute need for better treatment options to effectively manage this disease. Studies from different laboratories have shown that the Alzheimer disease-associated amyloid precursor protein (APP) is overexpressed in various cancers but its significance is not known. Here we sought to determine the role of APP in pancreatic cancer cell survival and proliferation. Our results show that pancreatic cancer cells secrete high levels of sAPPα, the α-secretase cleaved ectodomain fragment of APP, as compared with normal non-cancerous cells. Treatment of cells with batimastat or GI254023X, inhibitors of the α-secretase ADAM10, prevented sAPPα generation and reduced cell survival. Additionally, inhibition of sAPPα significantly reduced anchorage independent growth of the cancer cells. The effect of batimastat on cell survival and colony formation was enhanced when sAPPα downregulation was combined with gemcitabine treatment. Moreover, treatment of batimastat-treated cells with recombinant sAPPα reversed the inhibitory effect of the drug thereby indicating that sAPPα can indeed induce proliferation of cancer cells. Down-regulation of APP and ADAM10 brought about similar results, as did batimastat treatment, thereby confirming that APP processing is important for growth and proliferation of these cells. These results suggest that inhibition of sAPPα generation might enhance the effectiveness of the existing chemotherapeutic regimen for a better outcome.
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Affiliation(s)
- Neha Kabra Woods
- From the USF Health Byrd Alzheimer's Institute, Tampa, Florida 33613 and; the Department of Molecular Medicine, University of South Florida, Tampa, Florida 33612
| | - Jaya Padmanabhan
- From the USF Health Byrd Alzheimer's Institute, Tampa, Florida 33613 and; the Department of Molecular Medicine, University of South Florida, Tampa, Florida 33612.
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Yao J, Irwin R, Chen S, Hamilton R, Cadenas E, Brinton RD. Ovarian hormone loss induces bioenergetic deficits and mitochondrial β-amyloid. Neurobiol Aging 2012; 33:1507-21. [PMID: 21514693 PMCID: PMC3181273 DOI: 10.1016/j.neurobiolaging.2011.03.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 02/15/2011] [Accepted: 03/01/2011] [Indexed: 01/08/2023]
Abstract
Previously, we demonstrated that reproductive senescence was associated with mitochondrial deficits comparable to those of female triple-transgenic Alzheimer's mice (3xTgAD). Herein, we investigated the impact of chronic ovarian hormone deprivation and 17β-estradiol (E2) replacement on mitochondrial function in nontransgenic (nonTg) and 3xTgAD female mouse brain. Depletion of ovarian hormones by ovariectomy (OVX) in nontransgenic mice significantly decreased brain bioenergetics, and induced mitochondrial dysfunction and oxidative stress. In 3xTgAD mice, OVX significantly exacerbated mitochondrial dysfunction and induced mitochondrial β-amyloid and β-amyloid (Aβ)-binding-alcohol-dehydrogenase (ABAD) expression. Treatment with E2 at OVX prevented OVX-induced mitochondrial deficits, sustained mitochondrial bioenergetic function, decreased oxidative stress, and prevented mitochondrial β-amyloid and ABAD accumulation. In vitro, E2 increased maximal mitochondrial respiration in neurons and basal and maximal respiration in glia. Collectively, these data demonstrate that ovarian hormone loss induced a mitochondrial phenotype comparable to a transgenic female model of Alzheimer's disease (AD), which was prevented by E2. These findings provide a plausible mechanism for increased risk of Alzheimer's disease in premenopausally oophorectomized women while also suggesting a therapeutic strategy for prevention.
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Affiliation(s)
- Jia Yao
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90033
| | - Ronald Irwin
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90033
| | - Shuhua Chen
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90033
| | - Ryan Hamilton
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90033
| | - Enrique Cadenas
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90033
| | - Roberta Diaz Brinton
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90033
- Department of Neurology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
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Vieira SI, Rebelo S, Esselmann H, Wiltfang J, Lah J, Lane R, Small SA, Gandy S, da Cruz E Silva EF, da Cruz E Silva OA. Retrieval of the Alzheimer's amyloid precursor protein from the endosome to the TGN is S655 phosphorylation state-dependent and retromer-mediated. Mol Neurodegener 2010; 5:40. [PMID: 20937087 PMCID: PMC2994555 DOI: 10.1186/1750-1326-5-40] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 10/11/2010] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Retrograde transport of several transmembrane proteins from endosomes to the trans-Golgi network (TGN) occurs via Rab 5-containing endosomes, mediated by clathrin and the recently characterized retromer complex. This complex and one of its putative sorting receptor components, SorLA, were reported to be associated to late onset Alzheimer's disease (AD). The pathogenesis of this neurodegenerative disorder is still elusive, although accumulation of amyloidogenic Abeta is a hallmark. This peptide is generated from the sucessive β- and γ- secretase proteolysis of the Alzheimer's amyloid precursor protein (APP), events which are associated with endocytic pathway compartments. Therefore, APP targeting and time of residence in endosomes would be predicted to modulate Abeta levels. However, the formation of an APP- and retromer-containing protein complex with potential functions in retrieval of APP from the endosome to the TGN had, to date, not been demonstrated directly. Further, the motif(s) in APP that regulate its sorting to the TGN have not been characterized. RESULTS Through the use of APP-GFP constructs, we show that APP containing endocytic vesicles targeted for the TGN, are also immunoreactive for clathrin-, Rab 5- and VPS35. Further, they frequently generate protruding tubules near the TGN, supporting an association with a retromer-mediated pathway. Importantly, we show for the first time, that mimicking APP phosphorylation at S655, within the APP 653YTSI656 basolateral motif, enhances APP retrieval via a retromer-mediated process. The phosphomimetic APP S655E displays decreased APP lysosomal targeting, enhanced mature half-life, and decreased tendency towards Abeta production. VPS35 downregulation impairs the phosphorylation dependent APP retrieval to the TGN, and decreases APP half-life. CONCLUSIONS We reported for the first time the importance of APP phosphorylation on S655 in regulating its retromer-mediated sorting to the TGN or lysosomes. Significantly, the data are consistent with known interactions involving the retromer, SorLA and APP. Further, these findings add to our understanding of APP targeting and potentially contribute to our knowledge of sporadic AD pathogenesis representing putative new targets for AD therapeutic strategies.
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Affiliation(s)
- Sandra I Vieira
- Neuroscience, Centre for Cell Biology, Health Sciences Department SACS, University of Aveiro, Aveiro 3810, Portugal.
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Henriques AG, Vieira SI, da Cruz E Silva EF, da Cruz E Silva OAB. Abeta promotes Alzheimer's disease-like cytoskeleton abnormalities with consequences to APP processing in neurons. J Neurochem 2010; 113:761-71. [PMID: 20345756 DOI: 10.1111/j.1471-4159.2010.06643.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Abeta is proteolytically produced from the Alzheimer's amyloid precursor protein (APP). Major properties attributed to Abeta include neurotoxic effects that contribute to Alzheimer's disease neurodegeneration. However, Abeta can also affect APP processing and trafficking that, in neurons, is anterogradelly transported via microtubules in a kinesin-associated manner. Herein we show that Abeta can induce accumulation of intracellular sAPP in primary neuronal cultures. Subcellular fractionation studies and immunofluorescence analysis revealed that upon Abeta exposure sAPP retention was localized to cytoskeleton associated vesicular structures along the neurite processes, positive for an APP N-terminal antibody and negative for an APP C-terminal antibody. These vesicular structures were also positive for kinesin light chain 1 (KLC). We confirm that Abeta alters both actin and microtubule networks. It increases F-actin polymerization and we report for the first time that Abeta decreases alpha-tubulin acetylation. The use of cytoskeleton associated drugs partially reversed the Abeta-induced effects on sAPP secretion. The data here presented show that Abeta causes intracellular sAPP retention by inducing alterations in the cytoskeleton network, thus contributing to impaired APP/sAPP vesicular transport. Moreover, the data strengthens the hypothesis that Abeta-induces neurodegeneration and provides a potential mechanism of action, as impaired vesicular and axonal transport have been linked to Alzheimer's disease pathology.
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Affiliation(s)
- Ana Gabriela Henriques
- Laboratório de Neurociências, Centro de Biologia Celular, Universidade de Aveiro, Aveiro, Portugal
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12
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Kyriazis GA, Wei Z, Vandermey M, Jo DG, Xin O, Mattson MP, Chan SL. Numb endocytic adapter proteins regulate the transport and processing of the amyloid precursor protein in an isoform-dependent manner: implications for Alzheimer disease pathogenesis. J Biol Chem 2008; 283:25492-25502. [PMID: 18599481 PMCID: PMC2533073 DOI: 10.1074/jbc.m802072200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 07/01/2008] [Indexed: 01/10/2023] Open
Abstract
Central to the pathogenesis of Alzheimer disease is the aberrant processing of the amyloid precursor protein (APP) to generate amyloid beta-peptide (Abeta), the principle component of amyloid plaques. The cell fate determinant Numb is a phosphotyrosine binding domain (PTB)-containing endocytic adapter protein that interacts with the carboxyl-terminal domain of APP. The physiological relevance of this interaction is unknown. Mammals produce four alternatively spliced variants of Numb that differ in the length of their PTB and proline-rich region. In the current study, we determined the influence of the four human Numb isoforms on the intracellular trafficking and processing of APP. Stable expression of Numb isoforms that differ in the PTB but not in the proline-rich region results in marked differences in the sorting of APP to the recycling and degradative pathways. Neural cells expressing Numb isoforms that lack the insert in the PTB (short PTB (SPTB)) exhibited marked accumulation of APP in Rab5A-labeled early endosomal and recycling compartments, whereas those expressing isoforms with the insertion in the PTB (long PTB (LPTB)) exhibited reduced amounts of cellular APP and its proteolytic derivatives relative to parental control cells. Neither the activities of the beta- and gamma-secretases nor the expression of APP mRNA were significantly different in the stably transfected cells, suggesting that the differential effects of the Numb proteins on APP metabolism is likely to be secondary to altered APP trafficking. In addition, the expression of SPTB-Numb increases at the expense of LPTB-Numb in neuronal cultures subjected to stress, suggesting a role for Numb in stress-induced Abeta production. Taken together, these results suggest distinct roles for the human Numb isoforms in APP metabolism and may provide a novel potential link between altered Numb isoform expression and increased Abeta generation.
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Affiliation(s)
- George A Kyriazis
- Biomolecular Science Center, University of Central Florida, Orlando, Florida 32816
| | - Zelan Wei
- Biomolecular Science Center, University of Central Florida, Orlando, Florida 32816
| | - Miriam Vandermey
- Biomolecular Science Center, University of Central Florida, Orlando, Florida 32816
| | - Dong-Gyu Jo
- College of Pharmacy, Sungkyunkwan University, Suwon 440-746, Korea
| | - Ouyang Xin
- Laboratory of Neurosciences, NIA, National Institutes of Health, Intramural Research Program, Baltimore, Maryland 21224
| | - Mark P Mattson
- Laboratory of Neurosciences, NIA, National Institutes of Health, Intramural Research Program, Baltimore, Maryland 21224
| | - Sic L Chan
- Biomolecular Science Center, University of Central Florida, Orlando, Florida 32816.
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Grbovic OM, Mathews PM, Jiang Y, Schmidt SD, Dinakar R, Summers-Terio NB, Ceresa BP, Nixon RA, Cataldo AM. Rab5-stimulated up-regulation of the endocytic pathway increases intracellular beta-cleaved amyloid precursor protein carboxyl-terminal fragment levels and Abeta production. J Biol Chem 2003; 278:31261-8. [PMID: 12761223 DOI: 10.1074/jbc.m304122200] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously identified abnormalities of the endocytic pathway in neurons as the earliest known pathology in sporadic Alzheimer's disease (AD) and Down's syndrome brain. In this study, we modeled aspects of these AD-related endocytic changes in murine L cells by overexpressing Rab5, a positive regulator of endocytosis. Rab5-transfected cells exhibited abnormally large endosomes immunoreactive for Rab5 and early endosomal antigen 1, resembling the endosome morphology seen in affected neurons from AD brain. The levels of both Abeta40 and Abeta42 in conditioned medium were increased more than 2.5-fold following Rab5 overexpression. In Rab5 overexpressing cells, the levels of beta-cleaved amyloid precursor protein (APP) carboxyl-terminal fragments (betaCTF), the rate-limiting proteolytic intermediate in Abeta generation, were increased up to 2-fold relative to APP holoprotein levels. An increase in beta-cleaved soluble APP relative to alpha-cleaved soluble APP was also observed following Rab5 overexpression. BetaCTFs were co-localized by immunolabeling to vesicular compartments, including the early endosome and the trans-Golgi network. These results demonstrate a relationship between endosomal pathway activity, betaCTF generation, and Abeta production. Our findings in this model system suggest that the endosomal pathology seen at the earliest stage of sporadic AD may contribute to APP proteolysis along a beta-amyloidogenic pathway.
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Affiliation(s)
- Olivera M Grbovic
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York 10962, USA.
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14
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Maldonado TA, Jones RE, Norris DO. Timing of neurodegeneration and beta-amyloid (Abeta) peptide deposition in the brain of aging kokanee salmon. JOURNAL OF NEUROBIOLOGY 2002; 53:21-35. [PMID: 12360580 DOI: 10.1002/neu.10090] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Brains of kokanee salmon (Oncorhynchus nerka kennerlyi) in one of four reproductive stages (sexually immature, maturing, sexually mature, and spawning) were stained with cresyl violet and silver stain to visualize neurodegeneration. These reproductive stages correlate with increasing somatic aging of kokanee salmon, which die after spawning. Twenty-four regions of each brain were examined. Brains of sexually immature fish exhibited low levels of neurodegeneration, whereas neurodegeneration was more marked in maturing fish and greatest in spawning fish. Neurodegeneration was present in specific regions of the telencephalon, diencephalon, mesencephalon, and rhombencephalon. Pyknotic neurons were observed in all regions previously reported to be immunopositive for A beta. Regions that did not exhibit neurodegeneration during aging included the magnocellular vestibular nucleus, the nucleus lateralis tuberis of the hypothalamus, and Purkinje cells of the cerebellum, all of which also lack A beta; perhaps these regions are neuroprotected. In 14 of 16 brain areas for which data were available on both the increase in A beta deposition and pyknosis, neurodegeneration preceded or appeared more or less simultaneously with A beta production, whereas in only two regions did A beta deposition precede neurodegeneration. This information supports the hypothesis that A beta deposition is a downstream product of neurodegeneration in most brain regions. Other conclusions are that the degree of neurodegeneration varies among brain regions, neurodegeneration begins in maturing fish and peaks in spawning fish, the timing of neurodegeneration varies among brain regions, and some regions do not exhibit accelerated neurodegeneration during aging.
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Affiliation(s)
- Tammy A Maldonado
- Department of Environmental, Population and Organismic Biology, University of Colorado, 334 UCB, Boulder, Colorado 80309-0334, USA
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15
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Mathews PM, Jiang Y, Schmidt SD, Grbovic OM, Mercken M, Nixon RA. Calpain activity regulates the cell surface distribution of amyloid precursor protein. Inhibition of calpains enhances endosomal generation of beta-cleaved C-terminal APP fragments. J Biol Chem 2002; 277:36415-24. [PMID: 12087104 DOI: 10.1074/jbc.m205208200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In murine L cells, treatment with calpeptin or calpain inhibitor III increased Abeta42, but not Abeta40, secretion in a dose-dependent fashion. This correlated with an increase in the levels of amyloid precursor protein (APP) carboxyl-terminal fragments (CTFs). Immunoprecipitation with novel mAbs directed against the carboxyl-terminus of APP or specific for the beta-cleaved CTF showed that generation of both alpha- and beta-cleaved CTFs increase proportionately following inhibition of calpains. Pulse-chase metabolic labeling confirmed that inhibiting calpains increases the production of alpha- and beta-cleaved APP metabolites. Immunolabeling showed greater betaCTF signal in calpeptin-treated cells, primarily in small vesicular compartments that were shown to be predominantly endosomal by colocalization with early endosomal antigen 1. A second mAb, which recognizes an extracellular/luminal epitope found on both APP and betaCTFs, gave more cell surface labeling of calpeptin-treated cells than control cells. Quantitative binding of this antibody confirmed that inhibiting calpains caused a partial redistribution of APP to the cell surface. These results demonstrate that 1) calpain inhibition results in a partial redistribution of APP to the cell surface, 2) this redistribution leads to an increase in both alpha- and beta-cleavage without changing the ratio of alphaCTFs/betaCTFs, and 3) the bulk of the betaCTFs in the cell are within early endosomes, confirming the importance of this compartment in APP processing.
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Affiliation(s)
- Paul M Mathews
- Nathan Kline Institute, Orangeburg, New York 10962, USA.
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16
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Luo Y, Smith JV, Paramasivam V, Burdick A, Curry KJ, Buford JP, Khan I, Netzer WJ, Xu H, Butko P. Inhibition of amyloid-beta aggregation and caspase-3 activation by the Ginkgo biloba extract EGb761. Proc Natl Acad Sci U S A 2002; 99:12197-202. [PMID: 12213959 PMCID: PMC129421 DOI: 10.1073/pnas.182425199] [Citation(s) in RCA: 294] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2002] [Accepted: 07/18/2002] [Indexed: 11/18/2022] Open
Abstract
Standardized extract from the leaves of the Ginkgo biloba tree, labeled EGb761, has been used in clinical trials for its beneficial effects on brain functions, particularly in connection with age-related dementias and Alzheimer's disease (AD). Substantial experimental evidence indicates that EGb761 protects against neuronal damage from a variety of insults, but its cellular and molecular mechanisms remain unknown. Using a neuroblastoma cell line stably expressing an AD-associated double mutation, we report that EGb761 inhibits formation of amyloid-beta (Abeta) fibrils, which are the diagnostic, and possibly causative, feature of AD. The decreased Abeta fibrillogenesis in the presence of EGb761 was observed both in the conditioned medium of this Abeta-secreting cell line and in solution in vitro. In the cells, EGb761 significantly attenuated mitochondrion-initiated apoptosis and decreased the activity of caspase 3, a key enzyme in the apoptosis cell-signaling cascade. These results suggest that (i) neuronal damage in AD might be due to two factors: a direct Abeta toxicity and the apoptosis initiated by the mitochondria; and (ii) multiple cellular and molecular neuroprotective mechanisms, including attenuation of apoptosis and direct inhibition of Abeta aggregation, underlie the neuroprotective effects of EGb761.
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Affiliation(s)
- Yuan Luo
- Departments of Biological Sciences and Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, MS 39406, USA.
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17
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Ferroni S, Marchini C, Ogata T, Schubert P. Recovery of deficient cholinergic calcium signaling by adenosine in cultured rat cortical astrocytes. J Neurosci Res 2002; 68:615-21. [PMID: 12111851 DOI: 10.1002/jnr.10248] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The regulation of the cholinergic calcium signaling in astroglial cells is thought to play a crucial role in the pathogenesis of Alzheimer's disease. We investigated the action of the cell modulator adenosine on acetylcholine (Ach)-mediated intracellular calcium ([Ca(2+)](i)) transients in cultured rat cortical astrocytes using the Ca(2+) imaging technique. The stable adenosine analog 2-chloroadenosine (2ClA) potentiated the [Ca(2+)](i) rise induced by activation of muscarinic Ach receptors by shifting approximately 30-fold the half-effective Ach concentration. This 2ClA effect was maintained upon removal of extracellular Ca(2+), indicating that Ach-induced [Ca(2+)](i) elevation was due mainly to Ca(2+) mobilization from intracellular stores. Pharmacological studies demonstrated that the 2ClA action was mediated by A1 receptors. Incubation with pertussis toxin abrogated the 2ClA effect but left unchanged the [Ca(2+)](i) rise produced by Ach alone. The [Ca(2+)](i) response elicited by Ach alone was abolished upon blockade of muscarinic receptor subtypes that stimulate phospholipase C, whereas the [Ca(2+)](i) elevation generated by the combined action of subthreshold Ach and 2ClA was not affected. Collectively, these results suggest that the impaired cholinergic signaling, the cardinal symptom of Alzheimer's disease, can be reinforced at the second messenger level by an alternative intracellular Ca(2+) mobilizing path, which can be brought into play by the concomitant activation of A1 purinoceptors and muscarinic receptors negatively coupled to adenylyl cyclase.
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Affiliation(s)
- Stefano Ferroni
- Department of Human and General Physiology, University of Bologna, Bologna, Italy.
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18
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Pinnix I, Council JE, Roseberry B, Onstead L, Mallender W, Sucic J, Sambamurti K. Convertases other than furin cleave beta-secretase to its mature form. FASEB J 2001; 15:1810-2. [PMID: 11481238 DOI: 10.1096/fj.00-0891fje] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- I Pinnix
- Department of Neuroscience, Mayo Clinic, Jacksonville, Florida 32224, USA
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19
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Lannfelt L, Nordstedt C. Genetics of Alzheimer's disease--routes to the pathophysiology. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2001; 59:155-61. [PMID: 10961427 DOI: 10.1007/978-3-7091-6781-6_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Considerable advances have been made the last years in the understanding of the pathogenesis of Alzheimer's disease (AD): Several pathogenic mutations have been found in the amyloid precursor protein gene on chromosome 21. Two other dominantly operating genes on chromosome 14 and 1 were recently cloned, named presenilin 1 and 2, respectively. Mutations in these genes give rise to AD with a very early age of onset. Increased Abeta1-42 is most likely the pathogenic mechanism in all these cases. A susceptibility gene for AD has also been found. There is an association between the epsilon4 allele of the apolipoprotein E (APOE) gene and late-onset AD. The epsilon4 allele increases the risk for AD, although some epsilon4 homozygotes may live a long life without developing AD. The mechanism by which APOE epsilon4 promotes development of AD is most likely increased plaque formation. The new knowledge on pathogenic mechanisms of the disease gives opportunities for alternative strategies for therapeutic intervention.
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Affiliation(s)
- L Lannfelt
- Karolinska Institute, Department of Neurotec, Novum KFC, Huddinge University Hospital, Sweden
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20
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Pinnix I, Musunuru U, Tun H, Sridharan A, Golde T, Eckman C, Ziani-Cherif C, Onstead L, Sambamurti K. A novel gamma -secretase assay based on detection of the putative C-terminal fragment-gamma of amyloid beta protein precursor. J Biol Chem 2001; 276:481-7. [PMID: 11035007 DOI: 10.1074/jbc.m005968200] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alzheimer's disease is characterized by the deposits of the 4-kDa amyloid beta peptide (A beta). The A beta protein precursor (APP) is cleaved by beta-secretase to generate a C-terminal fragment, CTF beta, which in turn is cleaved by gamma-secretase to generate A beta. Alternative cleavage of the APP by alpha-secretase at A beta 16/17 generates the C-terminal fragment, CTFalpha. In addition to A beta, endoproteolytic cleavage of CTF alpha and CTF beta by gamma-secretase should yield a C-terminal fragment of 57-59 residues (CTF gamma). However, CTF gamma has not yet been reported in either brain or cell lysates, presumably due to its instability in vivo. We detected the in vitro generation of A beta as well as an approximately 6-kDa fragment from guinea pig brain membranes. We have provided biochemical and pharmacological evidence that this 6-kDa fragment is the elusive CTF gamma, and we describe an in vitro assay for gamma-secretase activity. The fragment migrates with a synthetic peptide corresponding to the 57-residue CTF gamma fragment. Three compounds previously identified as gamma-secretase inhibitors, pepstatin-A, MG132, and a substrate-based difluoroketone (t-butoxycarbonyl-Val-Ile-(S)-4-amino-3-oxo-2, 2-difluoropentanoyl-Val-Ile-OMe), reduced the yield of CTF gamma, providing additional evidence that the fragment arises from gamma-secretase cleavage. Consistent with reports that presenilins are the elusive gamma-secretases, subcellular fractionation studies showed that presenilin-1, CTF alpha, and CTF beta are enriched in the CTF gamma-generating fractions. The in vitro gamma-secretase assay described here will be useful for the detailed characterization of the enzyme and to screen for gamma-secretase inhibitors.
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Affiliation(s)
- I Pinnix
- Mayo Clinic, Jacksonville, Florida 32224, USA
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21
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Maldonado TA, Jones RE, Norris DO. Distribution of beta-amyloid and amyloid precursor protein in the brain of spawning (senescent) salmon: a natural, brain-aging model. Brain Res 2000; 858:237-51. [PMID: 10708675 DOI: 10.1016/s0006-8993(99)02328-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Brain amyloid precursor protein (APP), a normal constituent of neurons, glial cells and cerebrospinal fluid, has several proposed functions (e.g., in neuronal growth and survival). It appears, however, that altered processing of APP is an initial or downstream step in the neuropathology of brain aging, Alzheimer's disease (AD), and Down's syndrome (DS). Some studies suggest that proteolytic cleavage of APP, producing beta-amyloid (Abeta(1-42)), could have neurotoxic or neuroprotective effects. In this study, we utilized antibodies to human APP(695) and Abeta(1-42,) and Congo red staining, to search for amyloid deposition in the brain of semelparous spawning kokanee salmon (Oncorhynchus nerka kennerlyi). Intracellular APP(695) immunoreactivity (APP-ir) was observed in brain regions involved in gustation (glomerulosus complex), olfaction (putative hippocampus, olfactory bulb), vision (optic tectum), the stress response (nucleus preopticus and nucleus lateralis tuberis), reproductive behavior (nucleus preopticus magnocellularis, nucleus preopticus periventricularis, ventral telencephalon), and coordination (cerebellum). Intra- and extra-neuronal Abeta(1-42) immunoreactivity (Abeta-ir) were present in all APP-ir regions except the nucleus lateralis tuberis and Purkinje cells of the cerebellum (coordination). Thus, the relationship between APP and Abeta deposition during brain aging could shed light on the processing of APP into Abeta, neurodegeneration, and possible protection of neurons that are functioning in spawning but senescent salmon. Pacific salmon, with their predictable and synchronized life history, could provide research options not available with the existing models for studies of brain aging and amyloidosis.
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Affiliation(s)
- T A Maldonado
- Laboratory of Comparative Reproduction, Department of Environmental, Population and Organismic Biology, University of Colorado, Campus Box 334, Boulder, CO 80309-0334, USA.
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22
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Johnson JK, McCleary R, Oshita MH, Cotman CW. Initiation and propagation stages of beta-amyloid are associated with distinctive apolipoprotein E, age, and gender profiles. Brain Res 1998; 798:18-24. [PMID: 9666062 DOI: 10.1016/s0006-8993(98)00363-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Several recent studies have defined a relationship between apo-lipoprotein E (apoE) genotype and the risk of various neurodegenerative disorders. However, few studies have examined the influence of apoE on quantitative measures of beta-amyloid (Abeta) accumulation in a large population of autopsy cases. Using a multi-level analysis model, the interrelationships among apoE genotype, gender, age, and Abeta accumulation were investigated. In the population of these cases, there was a strong relationship between the presence of an epsilon4 allele and extent of Abeta in the frontal and entorhinal cortex. That is, when evaluating the presence or absence of significant Abeta (>1% Abeta load), subjects with one and two epsilon4 alleles were 1.9 and 3.5 times more likely to have significant Abeta accumulation than those with no epsilon4 alleles. These risks increased by a multiplicative factor of 1.014 for each year of age (at the time of death). In the subset of cases with significant Abeta (>1% Abeta load), the degree of Abeta load was best predicted by the presence of an epsilon2 allele and gender; females with no epsilon2 alleles had the highest Abeta loads (mean=12.3%), while males with one epsilon2 allele had the lowest amount of Abeta accumulation (mean=8.6%). Our results suggest that the presence of an epsilon4 allele predicts an earlier onset of Abeta deposition that is independent of gender. In contrast, once Abeta deposition has been initiated, the presence of an epsilon2 allele is associated with slower rates of accumulation, with males benefiting from the protective effect more than females.
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Affiliation(s)
- J K Johnson
- Institute for Brain Aging and Dementia, University of California-Irvine, Irvine, CA 92697-4285, USA.
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23
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Pallister C, Jung SS, Shaw I, Nalbantoglu J, Gauthier S, Cashman NR. Lymphocyte content of amyloid precursor protein is increased in Down's syndrome and aging. Neurobiol Aging 1997; 18:97-103. [PMID: 8983037 DOI: 10.1016/s0197-4580(96)00207-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We quantified cellular amyloid precursor protein (APP) in ethanol-permeabilized peripheral lymphocytes from 13 subjects with Alzheimer's disease (AD), 11 subjects with Down's syndrome (DS), and 13 healthy elderly and 31 healthy young controls. APP content was analyzed by indirect immunofluorescence and flow cytometry, using the 22C11 monoclonal antibody (mAb) directed against an N-terminal domain of APP. Authenticity of 22C11 APP signal was confirmed by immunoblotting and flow cytometry studies with the mAb 6E10, directed against the A beta domain of APP. Consistent with gene dosage, patients with DS had 1.51-fold higher lymphocyte APP signal than age-matched normal young subjects (corrected p < 0.05). Both AD patients and elderly control groups had significantly increased lymphocyte APP signal compared to young controls (either comparison corrected p < 0.01). Indeed, increasing age in non-DS subjects was significantly correlated with lymphocyte APP (r = 0.508, p < 0.0001), such that APP immunoreactivity more than doubled from 20 to 80 years. Lymphocyte APP was nonsignificantly higher in AD vs. aged controls in this small sample. Increased cellular APP content in DS and aging may correspond to generalized alterations in expression or processing of this molecule, and suggests a novel determinant for the timing of AD onset.
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Affiliation(s)
- C Pallister
- Department of Microbiology and Immunology, McGill Centre for Studies in Aging, McGill University, Montréal, Canada
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24
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Kaplitt M, Gouras GK, Makimura H, Jovanovic J, Sweeney D, Greengard P, Relkin NR, Gandy S. Apolipoprotein E, A beta-amyloid, and the molecular pathology of Alzheimer's disease. Therapeutic implications. Ann N Y Acad Sci 1996; 802:42-9. [PMID: 8993483 DOI: 10.1111/j.1749-6632.1996.tb32597.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- M Kaplitt
- Cornell University Medical College, New York, New York, USA
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25
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Messier C, Gagnon M. Glucose regulation and cognitive functions: relation to Alzheimer's disease and diabetes. Behav Brain Res 1996; 75:1-11. [PMID: 8800646 DOI: 10.1016/0166-4328(95)00153-0] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Glucose has been found to improve memory in animals and humans. Animal research has revealed that glucose may improve memory through a facilitation of acetylcholine (ACh) synthesis and release in the brain. This glucose-related memory improvement has prompted research in elderly humans. These studies have shown that the memory-improving action of glucose depends on each individuals' blood glucose regulation. Based on these data, researchers have evaluated the effect of glucose on memory in patients with Alzheimer's disease (AD). Results demonstrated that glucose could improve memory in a subset of patients that had abnormalities in their blood glucose regulation. Interestingly, these alterations in blood glucose regulation were believed to depend on the severity of the disease process. Another line of investigation has focused on alterations in brain glucose metabolism. Both animal models and studies with Type II diabetic elderly patients have shown that altered glucose regulation impairs learning and memory processes. It is possible that in AD patients, hyperglycemia exerts a deleterious effect by potentiating the neuronal death produced by other pathological processes taking place such as amyloid deposition. Based on these data, it appears important to find the prevalence of altered glucoregulation at various stages of AD. Secondly, it may be of interest to determine prospectively whether altered glucoregulation is linked to a faster progression of the disease. Finally, if such a relationship is observed, the next logical step would be to determine whether AD patients could benefit from treatments aimed at normalizing blood glucose regulation and improving insulin sensitivity.
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Affiliation(s)
- C Messier
- School of Psychology, University of Ottawa, Ontario, Canada.
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26
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Jaffe A, Toran-Allerand C, Greengard P, Gandy S. Estrogen regulates metabolism of Alzheimer amyloid beta precursor protein. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)36796-0] [Citation(s) in RCA: 254] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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27
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Gandy S, Greengard P. Regulated cleavage of the Alzheimer amyloid precursor protein: molecular and cellular basis. Biochimie 1994; 76:300-3. [PMID: 7819339 DOI: 10.1016/0300-9084(94)90162-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The relative utilization of alternative processing pathways for APP can be regulated by the activation state of certain protein phosphorylation signal transduction pathways. For example, activation of protein kinase C (PKC), or inactivation of protein phosphatases 1 and 2A, leads to a relative increase in utilization of the nonamyloidogenic, 'alpha-secretase' cleavage pathway for APP processing at the expense of other pathways. The molecular and cellular basis for this regulatory event is unknown. The possible mechanisms of regulated APP cleavage include (either singly or in combination): 1) substrate (ie APP) activation; 2) substrate redistribution; 3) enzyme (ie alpha-secretase) activation; or 4) enzyme redistribution. APP is a phosphoprotein; however, recent evidence from studies of the metabolism of mutant APP molecules suggests that changes in the APP cytoplasmic tail phosphorylation state may not be necessary for the phosphorylation-dependent activation of 'alpha-secretase' cleavage. Further, indirect immunofluorescent studies of the subcellular distribution of APP in the absence or presence of phorbol esters (PKC activators) fail to disclose obvious phorbol-induced redistribution of APP immunoreactivity. Taken together, current data suggest that major candidate phosphorylation-state sensitive targets relevant to the molecular basis of PKC-activated processing (or 'regulated cleavage') of APP include the APP ectodomain as well as secretase enzymes and/or other components of the APP trafficking/processing apparatus. Progress in distinguishing among these possibilities is discussed.
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Affiliation(s)
- S Gandy
- Department of Neurology and Neuroscience, Cornell University Medical College, New York, NY 10021
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