51
|
Reddy PH, Manczak M, Mao P, Calkins MJ, Reddy AP, Shirendeb U. Amyloid-beta and mitochondria in aging and Alzheimer's disease: implications for synaptic damage and cognitive decline. J Alzheimers Dis 2010. [PMID: 20413847 DOI: 10.3233/jad-2010-100504.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This article reviews the role of amyloid-beta (Abeta) and mitochondria in synaptic damage and cognitive decline found in patients with Alzheimer's disease (AD). Recent molecular, cellular, animal model, and postmortem brain studies have revealed that Abeta and mitochondrial abnormalities are key factors that cause synaptic damage and cognitive decline in AD. Abeta is reported to accumulate in subcellular compartments and to impair the normal function of neurons in AD patients. Further, recent studies using biochemical methods and electron microscopy have revealed that the accumulation of Abeta at nerve terminals affect synaptic activities, including the release of neurotransmitters and synaptic vesicles. Recent studies of the relationship between mitochondria and Abeta in AD patients suggest that in mitochondria, structural changes caused by Abeta result in increased mitochondrial fragmentation, decreased mitochondrial fusion, mitochondrial dysfunction, and synaptic damage. This paper discusses the latest research on Abeta, mitochondria, age-dependent factors of AD in the brain, and synaptic damage in AD. This paper also briefly discusses potential mitochondrial therapeutics in the treatment of patients with AD.
Collapse
Affiliation(s)
- P Hemachandra Reddy
- Neurogenetics Laboratory, Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA.
| | | | | | | | | | | |
Collapse
|
52
|
Reddy PH, Manczak M, Mao P, Calkins MJ, Reddy AP, Shirendeb U. Amyloid-beta and mitochondria in aging and Alzheimer's disease: implications for synaptic damage and cognitive decline. J Alzheimers Dis 2010; 20 Suppl 2:S499-512. [PMID: 20413847 DOI: 10.3233/jad-2010-100504] [Citation(s) in RCA: 192] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This article reviews the role of amyloid-beta (Abeta) and mitochondria in synaptic damage and cognitive decline found in patients with Alzheimer's disease (AD). Recent molecular, cellular, animal model, and postmortem brain studies have revealed that Abeta and mitochondrial abnormalities are key factors that cause synaptic damage and cognitive decline in AD. Abeta is reported to accumulate in subcellular compartments and to impair the normal function of neurons in AD patients. Further, recent studies using biochemical methods and electron microscopy have revealed that the accumulation of Abeta at nerve terminals affect synaptic activities, including the release of neurotransmitters and synaptic vesicles. Recent studies of the relationship between mitochondria and Abeta in AD patients suggest that in mitochondria, structural changes caused by Abeta result in increased mitochondrial fragmentation, decreased mitochondrial fusion, mitochondrial dysfunction, and synaptic damage. This paper discusses the latest research on Abeta, mitochondria, age-dependent factors of AD in the brain, and synaptic damage in AD. This paper also briefly discusses potential mitochondrial therapeutics in the treatment of patients with AD.
Collapse
Affiliation(s)
- P Hemachandra Reddy
- Neurogenetics Laboratory, Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA.
| | | | | | | | | | | |
Collapse
|
53
|
Head E, Pop V, Sarsoza F, Kayed R, Beckett TL, Studzinski CM, Tomic JL, Glabe CG, Murphy MP. Amyloid-beta peptide and oligomers in the brain and cerebrospinal fluid of aged canines. J Alzheimers Dis 2010; 20:637-46. [PMID: 20164551 DOI: 10.3233/jad-2010-1397] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The study of Alzheimer's disease (AD) pathogenesis requires the use of animal models that develop some amount of amyloid pathology in the brain. Aged canines (beagles) naturally accumulate human-type amyloid-beta peptide (Abeta) and develop parallel declines in cognitive function. However, the type and quantity of biochemically extracted Abeta in brain and cerebrospinal fluid (CSF), its link to aging, and similarity to human aging has not been examined systematically. Thirty beagles, aged 4.5-15.7 years, were studied. Abeta40 and Abeta42 were measured in CSF by ELISA, and from SDS and formic acid extracted prefrontal cortex. A sample of the contralateral hemisphere, used to assess immunohistochemical amyloid load, was used for comparison. In the brain, increases in Abeta42 were detected at a younger age, prior to increases in Abeta40, and were correlated with an increased amyloid load. In the CSF, Abeta42 decreased with age while Abeta40 levels remained constant. The CSF Abeta42/40 ratio was also a good predictor of the amount of Abeta in the brain. The amount of soluble oligomers in CSF was inversely related to brain extractable Abeta, whereas oligomers in the brain were correlated with SDS soluble Abeta42. These findings indicate that the Abeta in the brain of the aged canine exhibits patterns that mirror Abeta deposited in the human brain. These parallels support the idea that the aged canine is a useful intermediate between transgenic mice and humans for studying the development of amyloid pathology and is a potentially useful model for the refinement of therapeutic interventions.
Collapse
Affiliation(s)
- Elizabeth Head
- Department of Molecular and Biomedical Pharmacology and the Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536-0230, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
54
|
Huttunen HJ, Havas D, Peach C, Barren C, Duller S, Xia W, Frosch MP, Hutter-Paier B, Windisch M, Kovacs DM. The acyl-coenzyme A: cholesterol acyltransferase inhibitor CI-1011 reverses diffuse brain amyloid pathology in aged amyloid precursor protein transgenic mice. J Neuropathol Exp Neurol 2010; 69:777-88. [PMID: 20613640 PMCID: PMC2918281 DOI: 10.1097/nen.0b013e3181e77ed9] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Cerebral accumulation of amyloid-beta (Abeta) is characteristic of Alzheimer disease and of amyloid precursor protein (APP) transgenic mice. Here, we assessed the efficacy of CI-1011, an inhibitor of acyl-coenzyme A:cholesterol acyltransferase, which is suitable for clinical use, in reducing amyloid pathology in both young (6.5 months old) and aged (16 months old) human APP transgenic mice. Treatment of young animals with CI-1011 decreased amyloid plaque load in the cortex and hippocampus and reduced the levels of insoluble Abeta40 and Abeta42 and C-terminal fragments of APP in brain extracts. In aged mice, CI-1011 specifically reduced diffuse amyloid plaques with a minor effect on thioflavin S-positive dense-core plaques. Reduced diffusible amyloid was accompanied by suppression of astrogliosis and enhanced microglial activation. Collectively, these data suggest that CI-1011 treatment reduces amyloid burden in human APP mice by limiting generation and increasing clearance of diffusible Abeta.
Collapse
Affiliation(s)
- Henri J. Huttunen
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
- MassGeneral Institute for Neurodegenerative Disease (MIND) and Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
- Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Daniel Havas
- JSW-Research Forschungslabor GmbH, Institute of Experimental Pharmacology, Grambach/Graz, Austria
| | - Camilla Peach
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
- MassGeneral Institute for Neurodegenerative Disease (MIND) and Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
| | - Cory Barren
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
- MassGeneral Institute for Neurodegenerative Disease (MIND) and Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
| | - Stephan Duller
- JSW-Research Forschungslabor GmbH, Institute of Experimental Pharmacology, Grambach/Graz, Austria
| | - Weiming Xia
- Center for Neurologic Diseases, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Matthew P. Frosch
- MassGeneral Institute for Neurodegenerative Disease (MIND) and Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
| | - Birgit Hutter-Paier
- JSW-Research Forschungslabor GmbH, Institute of Experimental Pharmacology, Grambach/Graz, Austria
| | - Manfred Windisch
- JSW-Research Forschungslabor GmbH, Institute of Experimental Pharmacology, Grambach/Graz, Austria
| | - Dora M. Kovacs
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
- MassGeneral Institute for Neurodegenerative Disease (MIND) and Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
| |
Collapse
|
55
|
Niedowicz DM, Beckett TL, Holler CJ, Weidner AM, Murphy MP. APP(DeltaNL695) expression in murine tissue downregulates CNBP expression. Neurosci Lett 2010; 482:57-61. [PMID: 20621159 DOI: 10.1016/j.neulet.2010.07.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 06/18/2010] [Accepted: 07/02/2010] [Indexed: 11/20/2022]
Abstract
The cellular nucleic acid binding protein (CNBP) is a ubiquitously expressed protein involved in regulation of transcription and translation. CNBP, and its encoding gene ZNF9, have been shown to be involved in type 2 myotonic dystrophy. Both Alzheimer's disease (AD) and sporadic inclusion body myositis (sIBM) are age-related degenerative diseases associated with the accumulation of beta-amyloid. Overexpression of amyloid precursor protein (APP) in mice has been used to generate models of both diseases. We show here that overexpression of APP in skeletal muscle from a mouse model of sIBM reduces the expression of CNBP significantly. We examined CNBP expression in a brain-specific APP-overexpressing strain, and a whole body APP knock-in strain, and found that there was a reduction in CNBP expression in tissue expressing APP(Swe). We conclude that expression of APP(Swe) in murine tissue induces a decrease in CNBP expression. This effect does not appear to be due to alterations in CNBP transcription. APP(Swe) expression may provide a tool for the study of CNBP regulation and clues to the roles of both proteins in disease.
Collapse
Affiliation(s)
- Dana M Niedowicz
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | | | | | | | | |
Collapse
|
56
|
Liu Y, Studzinski C, Beckett T, Murphy MP, Klein RL, Hersh LB. Circulating neprilysin clears brain amyloid. Mol Cell Neurosci 2010; 45:101-7. [PMID: 20558294 DOI: 10.1016/j.mcn.2010.05.014] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2010] [Revised: 05/12/2010] [Accepted: 05/29/2010] [Indexed: 12/20/2022] Open
Abstract
The use of the peptidase neprilysin (NEP) as a therapeutic for lowering brain amyloid burden is receiving increasing attention. We have previously demonstrated that peripheral expression of NEP on the surface of hindlimb muscle lowers brain amyloid burden in a transgenic mouse model of Alzheimer's disease. In this study we now show that using adeno-associated virus expressing a soluble secreted form of NEP (secNEP-AAV8), NEP secreted into plasma is effective in clearing brain Abeta. Soluble NEP expression in plasma was sustained over the 3-month time period it was measured. Secreted NEP decreased plasma Abeta by 30%, soluble brain Abeta by approximately 28%, insoluble brain Abeta by approximately 55%, and Abeta oligomersby 12%. This secNEP did not change plasma levels of substance P or bradykinin, nor did it alter blood pressure. No NEP was detected in CSF, nor did the AAV virus produce brain expression of NEP. Thus the lowering of brain Abeta was due to plasma NEP which altered blood-brain Abeta transport dynamics. Expressing NEP in plasma provides a convenient way to monitor enzyme activity during the course of its therapeutic testing.
Collapse
Affiliation(s)
- Yinxing Liu
- Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, KY 40536-0509, USA
| | | | | | | | | | | |
Collapse
|
57
|
Effects of nonsteroidal anti-inflammatory drugs on amyloid-beta pathology in mouse skeletal muscle. Neurobiol Dis 2010; 39:449-56. [PMID: 20493261 DOI: 10.1016/j.nbd.2010.05.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Revised: 04/26/2010] [Accepted: 05/11/2010] [Indexed: 10/19/2022] Open
Abstract
Sporadic inclusion body myositis (sIBM) is a common age-related inflammatory myopathy characterized by the presence of intracellular inclusions that contain the amyloid-beta (Abeta) peptide, a derivative of the amyloid precursor protein (APP). Abeta is believed to cause Alzheimer's disease (AD), suggesting that a link may exist between the two diseases. If AD and sIBM are linked, then treatments that lower Abeta in brain may prove useful for sIBM. To test this hypothesis, transgenic mice that overexpress APP in skeletal muscle were treated for 6 months with a variety of nonsteroidal anti-inflammatory drugs (NSAIDs; naproxen, ibuprofen, carprofen or R-flurbiprofen), a subset of which reduce Abeta in brain and cultured cells. Only ibuprofen lowered Abeta in muscle, and this was not accompanied by corresponding improvements in phenotype. These results indicate that the effects of NSAIDs in the brain may be different from other tissues and that Abeta alone cannot account for skeletal muscle dysfunction in these mice.
Collapse
|
58
|
Pop V, Head E, Berchtold NC, Glabe CG, Studzinski CM, Weidner AM, Murphy MP, Cotman CW. Aβ aggregation profiles and shifts in APP processing favor amyloidogenesis in canines. Neurobiol Aging 2010; 33:108-20. [PMID: 20434811 DOI: 10.1016/j.neurobiolaging.2010.02.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 02/08/2010] [Accepted: 02/16/2010] [Indexed: 01/02/2023]
Abstract
The aged canine is a higher animal model that naturally accumulates β-amyloid (Aβ) and shows age-related cognitive decline. However, profiles of Aβ accumulation in different species (40 vs. 42), its assembly states, and Aβ precursor protein (APP) processing as a function of age remain unexplored. In this study, we show that Aβ increases progressively with age as detected in extracellular plaques and biochemically extractable Aβ40 and Aβ42 species. Soluble oligomeric forms of the peptide, with specific increases in an Aβ oligomer migrating at 56 kDa, also increase with age. Changes in APP processing could potentially explain why Aβ accumulates, and we show age-related shifts toward decreased total APP protein and nonamyloidogenic (α-secretase) processing coupled with increased amyloidogenic (β-secretase) cleavage of APP. Importantly, we describe Aβ pathology in the cingulate and temporal cortex and provide a description of oligomeric Aβ across the canine lifespan. Our findings are in line with observations in the human brain, suggesting that canines are a valuable higher animal model for the study of Aβ pathogenesis.
Collapse
Affiliation(s)
- Viorela Pop
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States.
| | | | | | | | | | | | | | | |
Collapse
|
59
|
Aluise CD, Robinson RAS, Beckett TL, Murphy MP, Cai J, Pierce WM, Markesbery WR, Butterfield DA. Preclinical Alzheimer disease: brain oxidative stress, Abeta peptide and proteomics. Neurobiol Dis 2010; 39:221-8. [PMID: 20399861 DOI: 10.1016/j.nbd.2010.04.011] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 04/06/2010] [Accepted: 04/09/2010] [Indexed: 02/03/2023] Open
Abstract
Alzheimer disease (AD) is a neurodegenerative disorder characterized clinically by progressive memory loss and subsequent dementia and neuropathologically by senile plaques, neurofibrillary tangles, and synapse loss. Interestingly, a small percentage of individuals with normal antemortem psychometric scores meet the neuropathological criteria for AD (termed 'preclinical' AD (PCAD)). In this study, inferior parietal lobule (IPL) from PCAD and control subjects was compared for oxidative stress markers by immunochemistry, amyloid beta peptide by ELISA, and identification of protein expression differences by proteomics. We observed a significant increase in highly insoluble monomeric Abeta42, but no significant differences in oligomeric Abeta nor in oxidative stress measurements between controls and PCAD subjects. Expression proteomics identified proteins whose trends in PCAD are indicative of cellular protection, possibly correlating with previous studies showing no cell loss in PCAD. Our analyses may reveal processes involved in a period of protection from neurodegeneration that mimic the clinical phenotype of PCAD.
Collapse
Affiliation(s)
- Christopher D Aluise
- Department of Chemistry, Center of Membrane Sciences, and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40506, USA
| | | | | | | | | | | | | | | |
Collapse
|
60
|
Sultana R, Banks WA, Butterfield DA. Decreased levels of PSD95 and two associated proteins and increased levels of BCl2 and caspase 3 in hippocampus from subjects with amnestic mild cognitive impairment: Insights into their potential roles for loss of synapses and memory, accumulation of Abeta, and neurodegeneration in a prodromal stage of Alzheimer's disease. J Neurosci Res 2010; 88:469-77. [PMID: 19774677 DOI: 10.1002/jnr.22227] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Alzheimer's disease (AD) is the most common form of dementia and is pathologically characterized by senile plaques, neurofibrillary tangles, synaptic disruption and loss, and progressive neuronal deficits. The exact mechanism(s) of AD pathogenesis largely remain unknown. With advances in technology diagnosis of a pre-AD stage referred to as amnestic mild cognitive impairment (MCI) has become possible. Amnestic MCI is characterized clinically by memory deficit, but normal activities of daily living and no dementia. In the present study, compared to controls, we observed in hippocampus from subjects with MCI a significantly decreased level of PSD95, a key synaptic protein, and also decreased levels of two proteins associated with PSD95, the N-methyl-D-aspartate receptor, subunit 2A (NR2A) and the low-density lipoprotein receptor-1 (LRP1). PSD95 and NR2A are involved in long-term potentiation, a key component of memory formation, and LRP1 is involved in efflux of amyloid beta-peptide (1-42). Abeta (1-42) conceivably is critical to the pathogenesis of MCI and AD, including the oxidative stress under which brain in both conditions exist. The data obtained from the current study suggest a possible involvement of these proteins in synaptic alterations, apoptosis and consequent decrements in learning and memory associated with the progression of MCI to AD.
Collapse
|
61
|
Age-related loss of phospholipid asymmetry in APP(NLh)/APP(NLh) x PS-1(P264L)/PS-1(P264L) human double mutant knock-in mice: relevance to Alzheimer disease. Neurobiol Dis 2010; 38:104-15. [PMID: 20083199 DOI: 10.1016/j.nbd.2010.01.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 12/26/2009] [Accepted: 01/07/2010] [Indexed: 12/12/2022] Open
Abstract
Using APP(NLh)/APP(NLh) x PS-1(P246L)/PS-1(P246L) human double knock-in (APP/PS-1) mice, we examined whether phosphatidylserine (PtdSer) asymmetry is significantly altered in brain of this familial Alzheimer disease mouse model in an age-dependent manner as a result of oxidative stress, toxic Abeta(1-42) oligomer production, and/or apoptosis. Annexin V (AV) and NBD-PS fluorescence in synaptosomes of wild-type (WT) and APP/PS-1 mice were used to determine PtdSer exposure with age, while Mg(2+) ATPase activity was determined to correlate PtdSer asymmetry changes with PtdSer translocase, flippase, activity. AV and NBD-PS results demonstrated significant PtdSer exposure beginning at 9 months compared to 1-month-old WT controls for both assays, a trend that was exacerbated in synaptosomes of APP/PS-1 mice. Decreasing Mg(2+) ATPase activity confirms that the age-related loss of PtdSer asymmetry is likely due to loss of flippase activity, more prominent in APP/PS-1 brain. Two-site sandwich ELISA on SDS- and FA-soluble APP/PS-1 brain fractions were conducted to correlate Abeta(1-40) and Abeta(1-42) levels with age-related trends determined from the AV, NBD-PS, and Mg(2+) ATPase assays. ELISA revealed a significant increase in both SDS- and FA-soluble Abeta(1-40) and Abeta(1-42) with age, consistent with PtdSer and flippase assay trends. Lastly, because PtdSer exposure is affected by pro-apoptotic caspase-3, levels of both latent and active forms were measured. Western blotting results demonstrated an increase in both active fragments of caspase-3 with age, while levels of pro-caspase-3 decrease. These results are discussed with relevance to loss of lipid asymmetry and consequent neurotoxicity in brain of subjects with Alzheimer disease.
Collapse
|
62
|
Abstract
Alzheimer's disease (AD) pathogenesis is widely believed to be driven by the production and deposition of the amyloid-beta peptide (Abeta). For many years, investigators have been puzzled by the weak to nonexistent correlation between the amount of neuritic plaque pathology in the human brain and the degree of clinical dementia. Recent advances in our understanding of the development of amyloid pathology have helped solve this mystery. Substantial evidence now indicates that the solubility of Abeta, and the quantity of Abeta in different pools, may be more closely related to disease state. The composition of these pools of Abeta reflects different populations of amyloid deposits and has definite correlates with the clinical status of the patient. Imaging technologies, including new amyloid imaging agents based on the chemical structure of histologic dyes, are now making it possible to track amyloid pathology along with disease progression in the living patient. Interestingly, these approaches indicate that the Abeta deposited in AD is different from that found in animal models. In general, deposited Abeta is more easily cleared from the brain in animal models and does not show the same physical and biochemical characteristics as the amyloid found in AD. This raises important issues regarding the development and testing of future therapeutic agents.
Collapse
Affiliation(s)
- M Paul Murphy
- Department of Molecular and Cellular Biochemistry and the Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536-0230, USA.
| | | |
Collapse
|
63
|
Ahmed RR, Holler CJ, Webb RL, Li F, Beckett TL, Murphy MP. BACE1 and BACE2 enzymatic activities in Alzheimer's disease. J Neurochem 2009; 112:1045-53. [PMID: 19968762 DOI: 10.1111/j.1471-4159.2009.06528.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
beta-Secretase is the rate limiting enzymatic activity in the production of the amyloid-beta peptide (Abeta) and is thought to be involved in Alzheimer's disease (AD) pathogenesis. Although BACE1 (beta-site APP Cleaving Enzyme 1, EC 3.4.23.46) has received significant attention, the related BACE2 (EC 3.4.23.45) has not. Though BACE2 is also expressed in the brain, its potential role in AD has not been resolved. In this study, we compared the activities of both BACE1 and BACE2, which were isolated from the same samples of frontal cortex from both AD-affected individuals and age-matched controls. BACE1 activity showed a significant positive correlation with the amount of extractable Abeta, and BACE1 protein and activity were significantly increased in AD cases. Unexpectedly, there were substantial total amounts of BACE2 protein and enzymatic activity in the human brain. BACE2 activity did not change significantly in the AD brain, and was not related to Abeta concentration. These data indicate that BACE1 likely accounts for most of the Abeta produced in the human brain, and that BACE2 activity is not a likely contributor. However, as both forms of BACE compete for the same substrate pool, even small changes in BACE2 activity could have consequences for human disease.
Collapse
Affiliation(s)
- Rachel R Ahmed
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, USA
| | | | | | | | | | | |
Collapse
|
64
|
Cognitive decline in Alzheimer's disease is associated with selective changes in calcineurin/NFAT signaling. J Neurosci 2009; 29:12957-69. [PMID: 19828810 DOI: 10.1523/jneurosci.1064-09.2009] [Citation(s) in RCA: 228] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Upon activation by calcineurin, the nuclear factor of activated T-cells (NFAT) translocates to the nucleus and guides the transcription of numerous molecules involved in inflammation and Ca(2+) dysregulation, both of which are prominent features of Alzheimer's disease (AD). However, NFAT signaling in AD remains relatively uninvestigated. Using isolated cytosolic and nuclear fractions prepared from rapid-autopsy postmortem human brain tissue, we show that NFATs 1 and 3 shifted to nuclear compartments in the hippocampus at different stages of neuropathology and cognitive decline, whereas NFAT2 remained unchanged. NFAT1 exhibited greater association with isolated nuclear fractions in subjects with mild cognitive impairment (MCI), whereas NFAT3 showed a strong nuclear bias in subjects with severe dementia and AD. Similar to NFAT1, calcineurin-Aalpha also exhibited a nuclear bias in the early stages of cognitive decline. But, unlike NFAT1 and similar to NFAT3, the nuclear bias for calcineurin became more pronounced as cognition worsened. Changes in calcineurin/NFAT3 were directly correlated to soluble amyloid-beta (Abeta((1-42))) levels in postmortem hippocampus, and oligomeric Abeta, in particular, robustly stimulated NFAT activation in primary rat astrocyte cultures. Oligomeric Abeta also caused a significant reduction in excitatory amino acid transporter 2 (EAAT2) protein levels in astrocyte cultures, which was blocked by NFAT inhibition. Moreover, inhibition of astrocytic NFAT activity in mixed cultures ameliorated Abeta-dependent elevations in glutamate and neuronal death. The results suggest that NFAT signaling is selectively altered in AD and may play an important role in driving Abeta-mediated neurodegeneration.
Collapse
|
65
|
Sultana R, Perluigi M, Butterfield DA. Oxidatively modified proteins in Alzheimer's disease (AD), mild cognitive impairment and animal models of AD: role of Abeta in pathogenesis. Acta Neuropathol 2009; 118:131-50. [PMID: 19288120 PMCID: PMC2818870 DOI: 10.1007/s00401-009-0517-0] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 03/04/2009] [Accepted: 03/05/2009] [Indexed: 02/06/2023]
Abstract
Oxidative stress has been implicated in the pathogenesis of a number of diseases including Alzheimer's disease (AD). The oxidative stress hypothesis of AD pathogenesis, in part, is based on beta-amyloid peptide (Abeta)-induced oxidative stress in both in vitro and in vivo studies. Oxidative modification of the protein may induce structural changes in a protein that might lead to its functional impairment. A number of oxidatively modified brain proteins were identified using redox proteomics in AD, mild cognitive impairment (MCI) and Abeta models of AD, which support a role of Abeta in the alteration of a number of biochemical and cellular processes such as energy metabolism, protein degradation, synaptic function, neuritic growth, neurotransmission, cellular defense system, long term potentiation involved in formation of memory, etc. All the redox proteomics-identified brain proteins fit well with the appearance of the three histopathological hallmarks of AD, i.e., synapse loss, amyloid plaque formation and neurofibrillary tangle formation and suggest a direct or indirect association of the identified proteins with the pathological and/or biochemical alterations in AD. Further, Abeta models of AD strongly support the notion that oxidative stress induced by Abeta may be a driving force in AD pathogenesis. Studies conducted on arguably the earliest stage of AD, MCI, may elucidate the mechanism(s) leading to AD pathogenesis by identifying early markers of the disease, and to develop therapeutic strategies to slow or prevent the progression of AD. In this review, we summarized our findings of redox proteomics identified oxidatively modified proteins in AD, MCI and AD models.
Collapse
Affiliation(s)
- Rukhsana Sultana
- Department of Chemistry, Center of Membrane Sciences, University of Kentucky, Lexington, KY 40506-0055, USA
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA
| | - Marzia Perluigi
- Department of Biochemical Sciences, University of Rome “La Sapienza”, Rome 00185, Italy
| | - D. Allan Butterfield
- Department of Chemistry, Center of Membrane Sciences, University of Kentucky, Lexington, KY 40506-0055, USA
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA
| |
Collapse
|
66
|
Liu Y, Studzinski C, Beckett T, Guan H, Hersh MA, Murphy MP, Klein R, Hersh LB. Expression of neprilysin in skeletal muscle reduces amyloid burden in a transgenic mouse model of Alzheimer disease. Mol Ther 2009; 17:1381-6. [PMID: 19471248 DOI: 10.1038/mt.2009.115] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Neprilysin (NEP) is a zinc metallopeptidase that efficiently degrades the amyloid beta (Abeta) peptides believed to be involved in the etiology of Alzheimer disease (AD). The focus of this study was to develop a new and tractable therapeutic approach for treating AD using NEP gene therapy. We have introduced adeno-associated virus (AAV) expressing the mouse NEP gene into the hindlimb muscle of 6-month-old human amyloid precursor protein (hAPP) (3X-Tg-AD) mice, an age which correlates with early stage AD. Overexpression of NEP in muscle decreased brain soluble Abeta peptide levels by approximately 60% and decreased amyloid deposits by approximately 50%, with no apparent adverse effects. Expression of NEP on muscle did not affect the levels of a number of other physiological peptides known to be in vitro substrates. These findings demonstrate that peripheral expression of NEP and likely other peptidases represents an alternative to direct administration into brain and illustrates the potential for using NEP expression in muscle for the prevention and treatment of AD.
Collapse
Affiliation(s)
- Yinxing Liu
- Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, Kentucky, USA
| | | | | | | | | | | | | | | |
Collapse
|
67
|
Guan H, Liu Y, Daily A, Police S, Kim MH, Oddo S, LaFerla FM, Pauly JR, Murphy MP, Hersh LB. Peripherally expressed neprilysin reduces brain amyloid burden: a novel approach for treating Alzheimer's disease. J Neurosci Res 2009; 87:1462-73. [PMID: 19021293 DOI: 10.1002/jnr.21944] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A number of therapeutic strategies for treating Alzheimer's disease have focused on reducing amyloid burden in the brain. Among these approaches, the expression of amyloid beta peptide (Abeta)-degrading enzymes in the brain has been shown to be effective but to date not practical for treating patients. We report here a novel strategy for lowering amyloid burden in the brain by peripherally expressing the Abeta-degrading enzyme neprilysin on leukocytes in the 3xTg-AD mouse model of Alzheimer's disease. Through transplantation of lentivirus-transduced bone marrow cells, the Abeta-degrading protease neprilysin was expressed on the surface of leukocytes. This peripheral neprilysin reduced soluble brain Abeta peptide levels by approximately 30% and lowered the accumulation of amyloid beta peptides by 50-60% when transplantation was performed at both young and early adult age. In addition, peripheral neprilysin expression reduced amyloid-dependent performance deficits as measured by the Morris water maze. Unlike other methods designed to lower Abeta levels in blood, which cause a net increase in peptide, neprilysin expression results in the catabolism of Abeta to small, innocuous peptide fragments. These findings demonstrate that peripherally expressed neprilysin, and likely other Abeta-degrading enzymes, has the potential to be utilized as a therapeutic approach to prevent and treat Alzheimer's disease and suggest that this approach should be explored further.
Collapse
Affiliation(s)
- Hanjun Guan
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40536-0509, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
68
|
Svedberg MM, Hall H, Hellström-Lindahl E, Estrada S, Guan Z, Nordberg A, Långström B. [(11)C]PIB-amyloid binding and levels of Abeta40 and Abeta42 in postmortem brain tissue from Alzheimer patients. Neurochem Int 2008; 54:347-57. [PMID: 19162107 DOI: 10.1016/j.neuint.2008.12.016] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 12/18/2008] [Accepted: 12/22/2008] [Indexed: 11/16/2022]
Abstract
beta-Amyloid (Abeta) deposits are one of the major histopathological hallmarks of Alzheimer's disease (AD). The amyloid-imaging positron emission tomography (PET) tracer [(11)C]PIB (N-methyl[(11)C]2-(4'-methylaminophenyl)-6-hydroxy-benzothiazole) is used in the assessment of Abeta deposits in the human brain. [(11)C]PIB-amyloid interaction and insoluble Abeta40 and Abeta42 peptide levels in the brain were quantified in postmortem tissue from nine AD patients and nine age-matched control subjects in the temporal, frontal and parietal cortices and the cerebellum. Autoradiographical studies showed significantly higher densities of specific [(11)C]PIB-amyloid binding in gray matter in the temporal and parietal cortex (62fmol/mg tissue) in AD patients as compared to control subjects, whereas the density was somewhat lower in the frontal cortex (56fmol/mg tissue). No specific binding could be detected in the AD cerebellum or in the tissues from the control subjects (< or =5fmol/mg tissue). Insoluble Abeta40 and total Abeta levels (i.e. sum of Abeta40 and Abeta42) were significantly higher in patients than in controls in all measured cortical regions as determined using ELISA, which was confirmed using immunohistochemistry. The present findings show a more regional selective distribution of [(11)C]PIB amyloid binding than previously reported. Moreover, it is suggested that some of the [(11)C]PIB binding and insoluble Abeta seen in control subjects may be amyloid in the blood vessels.
Collapse
Affiliation(s)
- Marie M Svedberg
- Uppsala University, Department of Biochemistry and Organic Chemistry, Sweden.
| | | | | | | | | | | | | |
Collapse
|
69
|
Studzinski CM, Li F, Bruce-Keller AJ, Fernandez-Kim SO, Zhang L, Weidner AM, Markesbery WR, Murphy MP, Keller JN. Effects of short-term Western diet on cerebral oxidative stress and diabetes related factors in APP x PS1 knock-in mice. J Neurochem 2008; 108:860-6. [PMID: 19046405 DOI: 10.1111/j.1471-4159.2008.05798.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A chronic high fat Western diet (WD) promotes a variety of morbidity factors although experimental evidence for short-term WD mediating brain dysfunction remains to be elucidated. The amyloid precursor protein and presenilin-1 (APP x PS1) knock-in mouse model has been demonstrated to recapitulate some key features of Alzheimer's disease pathology, including amyloid-beta (Abeta) pathogenesis. In this study, we placed 1-month-old APP x PS1 mice and non-transgenic littermates on a WD for 4 weeks. The WD resulted in a significant elevation in protein oxidation and lipid peroxidation in the brain of APP x PS1 mice relative to non-transgenic littermates, which occurred in the absence of increased Abeta levels. Altered adipokine levels were also observed in APP x PS1 mice placed on a short-term WD, relative to non-transgenic littermates. Taken together, these data indicate that short-term WD is sufficient to selectively promote cerebral oxidative stress and metabolic disturbances in APP x PS1 knock-in mice, with increased oxidative stress preceding alterations in Abeta. These data have important implications for understanding how WD may potentially contribute to brain dysfunction and the development of neurodegenerative disorders such as Alzheimer's disease.
Collapse
|
70
|
Molecular polymorphism of Abeta in Alzheimer's disease. Neurobiol Aging 2008; 31:542-8. [PMID: 18619711 DOI: 10.1016/j.neurobiolaging.2008.05.026] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Accepted: 05/28/2008] [Indexed: 01/04/2023]
Abstract
Alzheimer's disease is defined pathologically by the presence of senile plaques, which consist primarily of extracellular aggregates of fibrillar Abeta peptide, and neurofibrillary tangles, which are abnormal, intracellular bundles of fibrillar tau protein. The advent of amyloid binding agents as diagnostic imaging probes for Alzheimer's disease (AD) has made it imperative to understand at a molecular and disease level what these ligands are reporting. In addition to improving the accuracy of diagnosis, we argue that these selective ligands can serve as probes for molecular polymorphisms that may govern the pathogenicity of abnormal protein aggregates.
Collapse
|
71
|
Reddy PH, Beal MF. Amyloid beta, mitochondrial dysfunction and synaptic damage: implications for cognitive decline in aging and Alzheimer's disease. Trends Mol Med 2008; 14:45-53. [PMID: 18218341 DOI: 10.1016/j.molmed.2007.12.002] [Citation(s) in RCA: 698] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 12/02/2007] [Accepted: 12/03/2007] [Indexed: 01/10/2023]
Abstract
Recent studies of postmortem brains from Alzheimer's disease (AD) patients and transgenic mouse models of AD suggest that oxidative damage, induced by amyloid beta (Abeta), is associated with mitochondria early in AD progression. Abeta and amyloid-precursor protein are known to localize to mitochondrial membranes, block the transport of nuclear-encoded mitochondrial proteins to mitochondria, interact with mitochondrial proteins, disrupt the electron-transport chain, increase reactive oxygen species production, cause mitochondrial damage and prevent neurons from functioning normally. Furthermore, accumulation of Abeta at synaptic terminals might contribute to synaptic damage and cognitive decline in patients with AD. Here, we describe recent studies regarding the roles of Abeta and mitochondrial function in AD progression and particularly in synaptic damage and cognitive decline.
Collapse
Affiliation(s)
- P Hemachandra Reddy
- Neurogenetics Laboratory, Neurological Sciences Institute, Oregon Health and Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA.
| | | |
Collapse
|