451
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Abstract
Alzheimer's disease (AD) is the most common and devastating neurodegenerative disease of the elderly. Many research findings on familial AD suggest that the mechanisms of the pathogenesis of the disorder is more complex although the overall neuropathology of all cases of AD is surprisingly very similar. Genetic studies on some families have shown that mutations in the genes encoding beta-amyloid precursor protein and presenilins 1 and 2 are responsible for early-onset AD. In addition, apolipoprotein E gene allele E4 and the bleomycin hydrolase locus are shown to be genetic risk factors for late-onset AD in certain sporadic cases. Mitochondrial dysfunctions and age-related oxidative stress may also contribute to degenerative processes in AD. Although several studies support the amyloid cascade hypothesis as the mechanism of the disease, transgenic experiments and recent findings on a variant form of an AD family suggest that A beta deposition may not be sufficient to cause AD. Identification in the future of other genetic, environmental, and age-related factors, may provide additional targets for therapies.
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Affiliation(s)
- B S Shastry
- Eye Research Institute, Oakland University, Rochester, MI 48309, USA
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452
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Cappai R, Mok SS, Galatis D, Tucker DF, Henry A, Beyreuther K, Small DH, Masters CL. Recombinant human amyloid precursor-like protein 2 (APLP2) expressed in the yeast Pichia pastoris can stimulate neurite outgrowth. FEBS Lett 1999; 442:95-8. [PMID: 9923612 DOI: 10.1016/s0014-5793(98)01635-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The human amyloid precursor-like protein 2 (APLP2) is a member of the Alzheimer's disease amyloid precursor protein (APP) gene family. The human APLP2 ectodomain (sAPLP2) was expressed in the yeast Pichia pastoris and the recombinant sAPLP2 was purified from the culture medium in a single step by metal-chelating Sepharose chromatography. The neuritotrophic activity of APLP2 was compared to the APP isoforms sAPP695 and sAPP751 on chick sympathetic neurones. APLP2 had neurite outgrowth-promoting activity similar to that of the APP isoforms. This suggests that APP and APLP2 have a similar or related role and supports the idea of a redundancy in function between the APP-gene family proteins.
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Affiliation(s)
- R Cappai
- Department of Pathology, The University of Melbourne and The Mental Health Research Institute of Victoria, Parkville, Australia.
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453
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454
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Abstract
This article reviews the functional studies that have been carried out on transgenic and knockout animals that are relevant to Alzheimer's disease (AD). The discussion focuses upon the functional characterisation of these strains, particularly upon factors that affect synaptic processes that are thought to contribute to memory formation, including hippocampal long-term potentiation. We examine the use of transgenes associated with amyloid precursor protein and presenilin-1, their mutations linked to early onset familial AD, and the recent attempts to establish double transgenic strains that have an AD-like pathology which occurs with a more rapid onset. The development of new transgenic strains relevant to Alzheimer's disease has rapidly outpaced their characterisation for functional deficits in synaptic plasticity. To date most studies have focused on those transgenes linked to the minority of familial early onset rather than late-onset sporadic AD cases, and have focused on those changes linked to the induction of the early-phase of hippocampal long-term potentiation. Future studies will need to address the question of whether the development of AD pathology can be reversed or at least halted and this will be aided by the use of conditional transgenics in which genes linked to AD can either be switched on or off later in development. Furthermore, it remains to be resolved whether the deficits in synaptic function are specific to the hippocampus and whether deficits affect late-phase long-term potentiation. Nonetheless, the recent advances in genome sciences and the development of transgenic technology have provided a unique opportunity to study how genes associated with human cognitive dysfunction alter synaptic transmission between neurones in the mammalian brain.
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Affiliation(s)
- G R Seabrook
- Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, UK
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455
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Alzheimer amyloid protein precursor in the rat hippocampus: transport and processing through the perforant path. J Neurosci 1998. [PMID: 9822724 DOI: 10.1523/jneurosci.18-23-09629.1998] [Citation(s) in RCA: 186] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Amyloid deposition is a neuropathological hallmark of Alzheimer's disease. The principal component of amyloid deposits is beta amyloid peptide (Abeta), a peptide derived by proteolytic processing of the amyloid precursor protein (APP). APP is axonally transported by the fast anterograde component. Several studies have indicated that Abeta deposits occur in proximity to neuritic and synaptic profiles. Taken together, these latter observations have suggested that APP, axonally transported to nerve terminals, may be processed to Abeta at those sites. To examine the fate of APP in the CNS, we injected [35S]methionine into the rat entorhinal cortex and examined the trafficking and processing of de novo synthesized APP in the perforant pathway and at presynaptic sites in the hippocampal formation. We report that both full-length and processed APP accumulate at presynaptic terminals of entorhinal neurons. Finally, we demonstrate that at these synaptic sites, C-terminal fragments of APP containing the entire Abeta domain accumulate, suggesting that these species may represent the penultimate precursors of synaptic Abeta.
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456
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Fossgreen A, Brückner B, Czech C, Masters CL, Beyreuther K, Paro R. Transgenic Drosophila expressing human amyloid precursor protein show gamma-secretase activity and a blistered-wing phenotype. Proc Natl Acad Sci U S A 1998; 95:13703-8. [PMID: 9811864 PMCID: PMC24883 DOI: 10.1073/pnas.95.23.13703] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The importance of the amyloid precursor protein (APP) in the pathogenesis of Alzheimer's disease (AD) became apparent through the identification of distinct mutations in the APP gene, causing early onset familial AD with the accumulation of a 4-kDa peptide fragment (betaA4) in amyloid plaques and vascular deposits. However, the physiological role of APP is still unclear. In this work, Drosophila melanogaster is used as a model system to analyze the function of APP by expressing wild-type and various mutant forms of human APP in fly tissue culture cells as well as in transgenic fly lines. After expression of full-length APP forms, secretion of APP but not of betaA4 was observed in both systems. By using SPA4CT, a short APP form in which the signal peptide was fused directly to the betaA4 region, transmembrane domain, and cytoplasmic tail, we observed betaA4 release in flies and fly-tissue culture cells. Consequently, we showed a gamma-secretase activity in flies. Interestingly, transgenic flies expressing full-length forms of APP have a blistered-wing phenotype. As the wing is composed of interacting dorsal and ventral epithelial cell layers, this phenotype suggests that human APP expression interferes with cell adhesion/signaling pathways in Drosophila, independently of betaA4 generation.
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Affiliation(s)
- A Fossgreen
- Center for Molecular Biology, University of Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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457
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Naruse S, Thinakaran G, Luo JJ, Kusiak JW, Tomita T, Iwatsubo T, Qian X, Ginty DD, Price DL, Borchelt DR, Wong PC, Sisodia SS. Effects of PS1 deficiency on membrane protein trafficking in neurons. Neuron 1998; 21:1213-21. [PMID: 9856475 DOI: 10.1016/s0896-6273(00)80637-6] [Citation(s) in RCA: 295] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have examined the trafficking and metabolism of the beta-amyloid precursor protein (APP), an APP homolog (APLP1), and TrkB in neurons that lack PS1. We report that PS1-deficient neurons fail to secrete Abeta, and that the rate of appearance of soluble APP derivatives in the conditioned medium is increased. Remarkably, carboxyl-terminal fragments (CTFs) derived from APP and APLP1 accumulate in PS1-deficient neurons. Hence, PS1 plays a role in promoting intramembrane cleavage and/or degradation of membrane-bound CTFs. Moreover, the maturation of TrkB and BDNF-inducible TrkB autophosphorylation is severely compromised in neurons lacking PS1. We conclude that PS1 plays an essential role in modulating trafficking and metabolism of a selected set of membrane and secretory proteins in neurons.
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Affiliation(s)
- S Naruse
- Department of Pharmacological and Physiological Sciences, The University of Chicago, Illinois 60637, USA
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458
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Henry A, Li QX, Galatis D, Hesse L, Multhaup G, Beyreuther K, Masters CL, Cappai R. Inhibition of platelet activation by the Alzheimer's disease amyloid precursor protein. Br J Haematol 1998; 103:402-15. [PMID: 9827912 DOI: 10.1046/j.1365-2141.1998.01005.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The amyloid precursor protein (APP) of Alzheimer's disease is abundantly expressed in the platelet alpha-granule where its role remains unclear. This study describes a novel function for APP in regulating human platelet activation. Preincubation of platelet-rich plasma with recombinant secreted APP (sAPP) isoforms dose-dependently inhibited platelet aggregation and secretion induced by ADP or adrenaline. Similarly, sAPP potently inhibited low-dose thrombin-induced activation in washed platelet suspensions, indicating that the activity does not require plasma cofactors. There were no functional differences between sAPP forms with or without the Kunitz protease inhibitor domain or derived from either alpha- or beta-secretase cleavage. In fact, the N-terminal cysteine-rich region of APP (residues 18-194) was as effective as the entire sAPP region in the inhibition of platelet activation. The inhibitory activity of sAPP correlated with a significant reduction in the agonist-induced production of the arachidonic acid (AA) metabolites thromboxane B2 and prostaglandin E2. However, sAPP did not affect AA-induced platelet aggregation or secretion, indicating the enzymatic conversion of AA was not inhibited. The addition of a threshold dose of AA reversed the sAPP-inhibition of agonist-induced platelet activation. This suggests that sAPP decreases the availability of free AA, although the mechanism is not yet known. These data provide evidence that the release of sAPP upon platelet degranulation may result in negative feedback regulation during platelet activation.
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Affiliation(s)
- A Henry
- Department of Pathology, University of Melbourne and Mental Health Research Institute of Victoria, Parkville, Australia
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459
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Sisodia SS, Gallagher M. A role for the beta-amyloid precursor protein in memory? Proc Natl Acad Sci U S A 1998; 95:12074-6. [PMID: 9770440 PMCID: PMC33903 DOI: 10.1073/pnas.95.21.12074] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- S S Sisodia
- Department of Pharmacological and Physiological Sciences, The University of Chicago, 947 E. 58th Street, Abbott 316, Chicago, IL 60637, USA.
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460
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Picciotto MR, Wickman K. Using knockout and transgenic mice to study neurophysiology and behavior. Physiol Rev 1998; 78:1131-63. [PMID: 9790572 DOI: 10.1152/physrev.1998.78.4.1131] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Reverse genetics, in which detailed knowledge of a gene of interest permits in vivo modification of its expression or function, provides a powerful method for examining the physiological relevance of any protein. Transgenic and knockout mouse models are particularly useful for studies of complex neurobiological problems. The primary aims of this review are to familiarize the nonspecialist with the techniques and limitations of mouse mutagenesis, to describe new technologies that may overcome these limitations, and to illustrate, using representative examples from the literature, some of the ways in which genetically altered mice have been used to analyze central nervous system function. The goal is to provide the information necessary to evaluate critically studies in which mutant mice have been used to study neurobiological problems.
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Affiliation(s)
- M R Picciotto
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA
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461
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Survival of cultured neurons from amyloid precursor protein knock-out mice against Alzheimer's amyloid-beta toxicity and oxidative stress. J Neurosci 1998. [PMID: 9698314 DOI: 10.1523/jneurosci.18-16-06207.1998] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Studies on the amyloid precursor protein (APP) have suggested that it may be neuroprotective against amyloid-beta (Abeta) toxicity and oxidative stress. However, these findings have been obtained from either transfection of cell lines and mice that overexpress human APP isoforms or pretreatment of APP-expressing primary neurons with exogenous soluble APP. The neuroprotective role of endogenously expressed APP in neurons exposed to Abeta or oxidative stress has not been determined. This was investigated using primary cortical and cerebellar neuronal cultures established from APP knock-out (APP-/-) and wild-type (APP+/+) mice. Differences in susceptibility to Abeta toxicity or oxidative stress were not found between APP-/- and APP+/+ neurons. This observation may reflect the expression of the amyloid precursor-like proteins 1 and 2 (APLP1 and APLP2) molecules and supports the theory that APP and the APLPs may have similar functional activities. Increased expression of cell-associated APLP2, but not APLP1, was detected in Abeta-treated APP-/- and APP+/+ cultures but not in H2O2-treated cultures. This suggests that the Abeta toxicity pathway differs from other general forms of oxidative stress. These findings show that Abeta toxicity does not require an interaction of the Abeta peptide with the parental molecule (APP) and is therefore distinct from prion protein neurotoxicity that is dependent on the expression of the parental cellular prion protein.
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462
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Tremml P, Lipp HP, Müller U, Ricceri L, Wolfer DP. Neurobehavioral development, adult openfield exploration and swimming navigation learning in mice with a modified beta-amyloid precursor protein gene. Behav Brain Res 1998; 95:65-76. [PMID: 9754878 DOI: 10.1016/s0166-4328(97)00211-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The processing of beta-amyloid precursor protein (betaAPP) and its metabolites plays an important role in the pathogenesis of Alzheimer's disease (AD) and Down's syndrome. The authors have reported elsewhere that a targeted mutation resulting in low expression of a shortened betaAPP protein (betaAPP(delta/delta)) entails reduced learning abilities. Here the authors investigate whether these effects were caused by postnatal developmental actions of the altered protein. The authors examined 35 mice carrying the betaAPP(delta/delta) mutation for somatic growth and sensorimotor development during the first 4 postnatal weeks (pw) and compared them with 31 wildtype litter-mates. Thereafter, the same mice were tested at about 10 weeks of age for openfield behavior and for swimming navigation learning. Mutant mice showed both transient and long-lasting deficits in development. Body weight deficit started to emerge at postnatal day (pd) 12, peaked with a 15.1% deficit at pd 27 and lasted until pw 33-37. Significant transient deficits in mutant mice during sensorimotor development were observed in three time windows (pd 3-10, pd 11-19 and pd 20-27), long-lasting effects, manifest at pw 8-12 and pw 33-37, emerged at any of the three periods. In the adult mice, exploratory activity of betaAPP mutants in the openfield arena was severely reduced. In the Morris water maze task, mutant mice showed moderate escape performance deficits during the acquisition period but no impairment in spatial memory. The authors conclude that a defective betaAPP gene impairs postnatal somatic development, associated with transient as well as long-lasting neurobehavioral retardation and muscular weakness. Comparison with earlier data suggests that early postnatal handling may attenuate some of the non-cognitive performance deficits in the water maze. Further, the manifestation and time course of behavioral yet not neuropathological symptoms in betaAPP mutant mice resemble in some aspects those of the human Down's syndrome.
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Affiliation(s)
- P Tremml
- Institute of Anatomy, University of Zürich-Irchel, Zürich, Switzerland
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463
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Rassoulzadegan M, Yang Y, Cuzin F. APLP2, a member of the Alzheimer precursor protein family, is required for correct genomic segregation in dividing mouse cells. EMBO J 1998; 17:4647-56. [PMID: 9707424 PMCID: PMC1170794 DOI: 10.1093/emboj/17.16.4647] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The mouse amyloid precursor-like protein 2 (APLP2) belongs to the Alzheimer peptide precursor family. A possible role in pre-implantation development had been suggested previously, and was investigated further by creating a large deletion in the genomic locus. While heterozygous mice developed normally, homozygous embryos were arrested before reaching the blastocyst stage. One-cell embryos which contained protein of maternal origin underwent a limited number of cleavages. The progressive disappearance of the protein at stages 4 and beyond correlated with the appearance of extensive cytopathological effects. Nuclear DNA contents of the arrested embryos departed widely from the normal 2-4C value, thus suggesting a role for the protein in replication and/or segregation of the embryonic genome. Embryonic mortality was not due to the untimely initiation of programmed cell death, and it occurred before the stage at which apoptotic cells normally appear. The same abnormal distribution of DNA contents was seen in primary cultures of Aplp2 +/- embryonic fibroblasts following transfection of an expression vector for Aplp2 antisense RNA with green fluorescent protein (GFP) expressed from a co-transfected construct. Daughter cells derived from a GFP-positive cell showed abnormal DNA contents both >4C and <2C, thus indicating a role for the protein in the mitotic segregation of the genome and establishment of the proper nuclear structure.
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Affiliation(s)
- M Rassoulzadegan
- Unité 470 de l'Institut National de la Santé et de la Recherche Médicale, Université de Nice, 06108 Nice, France.
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464
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Affiliation(s)
- E H Buhl
- MRC Anatomical Neuropharmacology Unit, Oxford University, United Kingdom
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465
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Abstract
Chronic low-level lead exposure is toxic to the developing nervous system. The amyloid beta precursor protein (A beta PP) plays a pivotal role in this developmental process, both as a neurotrophic/neuroprotective factor and as a mediator of cell adhesion. In this study, we have used an in vitro system to examine the interaction between chronic low-level lead and the expression and function of A beta PP. Chronic exposure of the HN9 mouse hippocampal cell line to lead chloride (10(-14) M to 10(-6) M) for 96 hours resulted in a 50% increase in the levels of the particulate form of the protein with a parallel decrease in the soluble form (A beta PP). This effect of lead was reversible following the removal of the toxin. This increase in membrane-bound A beta PP was also paralleled by an increase in cell adhesivity to a fibronectin substrate. In addition, A beta PP also acted to attenuate lead toxicity. Cells which secreted high levels of the protein were resistant to lead toxicity when compared with control cells suggesting that the protein may be acting to chelate the metal and thus attenuating its toxic action within the cell.
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Affiliation(s)
- F D Davey
- Department of Pharmacology and Neuroscience, University of Dundee, Ninewells Hospital Medical School, Scotland, UK
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466
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Nitsch RM, Kim C, Growdon JH. Vasopressin and bradykinin regulate secretory processing of the amyloid protein precursor of Alzheimer's disease. Neurochem Res 1998; 23:807-14. [PMID: 9566621 DOI: 10.1023/a:1022423813362] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The amyloid protein precursor (APP) can be processed via several alternative processing pathways. Alpha-secretase processing by cleavage within the amyloid beta-peptide domain of APP is highly regulated by several external and internal signals including G protein-coupled receptors, protein kinase C and phospholipase A2. In order to demonstrate that G protein-coupled neuropeptide receptors for bradykinin and vasopressin can increase alpha-secretase processing of APP, we stimulated endogenously expressed bradykinin or vasopressin receptors in cell culture with the neuropeptides and measured the secreted ectodomain (APPs) in the conditioned media. Both bradykinin and vasopressin rapidly increased phosphatidylinositol (PI) turnover in PC-12 and in NRK-49F cells, indicating that these cell lines constitutively expressed functional PI-linked receptors for these neuropeptides. Both bradykinin and vasopressin readily stimulated APPs secretion. Increased APPs secretion was concentration-dependent and saturable, and it was blocked by receptor antagonists indicating specific receptor interaction of the peptides. The bradykinin-induced increase in APPs secretion in PC-12 cells was mediated by protein kinase C (PKC), whereas vasopressin receptors in NRK-49F cells were coupled to APP processing by PKC-independent signalling pathways. Our data show that neuropeptides can modulate APP processing in cell culture. In as much as increased alpha-secretase processing is associated with decreased formation of A beta(1-40), a major constituent of amyloid plaques, our findings suggest a possible role for modulating neuropeptide receptors as a strategy for altering amyloid metabolism in Alzheimer's disease brain.
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Affiliation(s)
- R M Nitsch
- Center for Molecular Neurobiology, University of Hamburg, Germany.
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467
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Abstract
The most common cause of dementia occurring in mid- to late-life is Alzheimer's disease (AD). Some cases of AD, particularly those of early onset, are familial and inherited as autosomal dominant disorders linked to the presence of mutant genes that encode the amyloid precursor protein (APP) or the presenilins (PS1 or PS2). These mutant gene products cause dysfunction/death of vulnerable populations of nerve cells important in memory, higher cognitive processes, and behavior. AD affects 7-10% of individuals > 65 years of age and perhaps 40% of individuals > 80 years of age. For the late-onset cases, the principal risk factors are age and apolipoprotein (apoE) allele type, with apoE4 allele being a susceptibility factor. In this review, we briefly discuss the clinical syndrome of AD and the neurobiology/neuropathology of the disease and then focus attention on mutant genes linked to autosomal dominant familial AD (FAD), the biology of the proteins encoded by these genes, and the recent exciting progress in investigations of genetically engineered animal models that express these mutant genes and develop some features of AD.
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Affiliation(s)
- D L Price
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2196, USA. ,
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468
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Allain H, Bentué-Ferrer D, Zekri O, Schück S, Lebreton S, Reymann JM. Experimental and clinical methods in the development of anti-Alzheimer drugs. Fundam Clin Pharmacol 1998; 12:13-29. [PMID: 9523180 DOI: 10.1111/j.1472-8206.1998.tb00919.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methodology used for the development of anti-Alzheimer's disease (AD) drugs raises specific problems which are rarely examined in the literature. While the general development scheme is similar to that required for most drugs, some specific aspects must be analyzed, highly dominated by the dual goal of pharmacology, i.e., to obtain both symptomatic and etiopathogenic drugs. During preclinical studies, aged or lesioned animals are mainly useful for symptomatic drugs, whereas transgenic models or neurodegeneration-induced techniques would probably lead to etiopathogenic drugs potentially slowing down the process of AD. The first administrations of a new compound to human beings raise the question of the activity measurement techniques. Psychometry remains the most informative procedure to detect and analyze the activity of the drugs on the different components of cognition. Electrophysiology and neuroimaging need some complementary studies before they can be proposed as surrogate criteria in phase III trials. At this stage of development, American and the recently published European guidelines are of great help while insisting on long-term (6 months) placebo controlled trials with the use of the triple efficacy criterion: an objective cognition scale, a global assessment, and the opinion of the caregiver. In the long term, pharmacoepidemiology and pharmacoeconomy will have to confirm the rationale of this recent progress in the methodology of anti-AD drug development.
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Affiliation(s)
- H Allain
- Laboratoire de Pharmacologie Expérimentale et Clinique, Faculté de Médecine, Rennes, France
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469
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Abstract
Alzheimer disease (AD) is a genetically heterogeneous and progressive degenerative disorder of the brain. It affects approximately 4 million Americans and causes more than 100,000 deaths each year, and there is no cure. It is estimated that by the year 2020, 14 million Americans will be affected by the disease. Although the major pathology is confined to regions of the brain, some patients show an impaired sense of smell and selective loss of retinal ganglion cells. The biochemical processes that lead to AD are largely unknown. Genetic studies on inherited AD have identified three genes that when mutated can cause an early-onset form of the disease. Mutation of these genes has been shown to increase the production of a unique protein called beta-amyloid, which is the predominant component of neuritic plaques found in the brain of AD patients. Also, one susceptibility gene has been shown to be associated with the risk of late-onset AD in both familial and sporadic forms. The available data support to a large extent the amyloid cascade hypothesis as a mechanism of the disease pathology. The newly identified "AMY plaques" and the future identification of other susceptibility genes may give further clues to the neurodegenerative mechanisms of AD.
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Affiliation(s)
- B S Shastry
- Eye Research Institute, Oakland University, Rochester, Michigan 48309-4480, USA
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470
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Molecular Genetics of Familial Alzheimer Disease. Am J Med Sci 1998. [DOI: 10.1016/s0002-9629(15)40324-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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471
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Abstract
Gene targeting technology in mice by homologous recombination has become an important method to generate loss-of-function of genes in a predetermined locus. Although the inactivation is limited to irreversible alteration of chromosomal DNA and a surprising variety of genes have given unexpected and disappointing results, modification of the basic technology now provides additional choices for a more specific and variety of manipulations of the mouse genome. This includes conditional cell-type specific gene targeting, knockin technique and the induction of the specific balanced chromosomal translocations. In the past decade this technique not only generated a wealth of knowledge concerning the roles of growth factors, oncogenes, hormone receptors and Hox genes but also helped to produce animal models for several human genetic disorders. In the future it may provide more powerful and necessary tools to dissect the psychiatric disorders, understanding the complex central nervous system and to correct the inherited disorders.
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Affiliation(s)
- B S Shastry
- Eye Research Institute, Oakland University, Rochester, Missouri 48309, USA
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472
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Affiliation(s)
- M A Smith
- Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA
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473
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The beta-amyloid precursor protein of Alzheimer's disease enhances neuron viability and modulates neuronal polarity. J Neurosci 1998. [PMID: 9390996 DOI: 10.1523/jneurosci.17-24-09407.1997] [Citation(s) in RCA: 169] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
beta-Amyloid precursor protein (betaPP) can reside at neuron and glial cell surfaces or undergo proteolytic processing into secreted fragments. Although betaPP has been studied extensively, its precise physiological role is unknown. A line of transgenic knock-out mice selectively deficient in betaPP survive and breed but exhibit motor dysfunction and brain gliosis, consistent with a physiological role for betaPP in neuron development. To elucidate these functions, we cultured hippocampal neurons from wild-type and betaPP-deficient mice and compared their ability to attach, survive, and develop neurites. We found that hippocampal neurons from betaPP-deficient mice had diminished viability and retarded neurite development. We also compared the effects of betaPP secretory products, released from wild-type astrocytes, on process outgrowth from wild-type and betaPP-deficient hippocampal neurons. Outgrowth was enhanced at 1 d in the presence of wild-type astrocytes, as compared with betaPP-deficient astrocytes. However, by 3 d, neurons had shorter axons but more minor processes with more branching when cocultured with wild-type astrocytes, as compared with betaPP-deficient astrocytes. Our data demonstrate that cell-associated neuronal betaPP contributes to neuron viability, axonogenesis, and arborization and that betaPP secretory products modulate axon growth, dendrite branching, and dendrite numbers.
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474
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Panegyres PK. The amyloid precursor protein gene: a neuropeptide gene with diverse functions in the central nervous system. Neuropeptides 1997; 31:523-35. [PMID: 9574821 DOI: 10.1016/s0143-4179(97)90000-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The amyloid precursor protein (APP) is a member of a family of proteins found in the central nervous system with a fundamental role in the pathogenesis of Alzheimer's disease. This review describes the experimental evidence that has provided functional insights into this protein and emphasizes the importance of APP in many neurobiological processes.
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Affiliation(s)
- P K Panegyres
- Department of Neuropathology, Royal Perth Hospital, Western Australia.
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475
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Ridet JL, Malhotra SK, Privat A, Gage FH. Reactive astrocytes: cellular and molecular cues to biological function. Trends Neurosci 1997; 20:570-7. [PMID: 9416670 DOI: 10.1016/s0166-2236(97)01139-9] [Citation(s) in RCA: 1327] [Impact Index Per Article: 49.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
For several decades, the reactive gliosis that occurs after an injury to the CNS has been considered one of the major impediments to axonal regeneration. Nevertheless, recent studies have suggested that in certain conditions, reactive astrocytes may provide a permissive substratum to support axonal regrowth. The important criteria, allowing for the distinction between permissive and non-permissive gliosis, are the ultrastructural 3D organization of the scar and more importantly the recognition molecules expressed by reactive astrocytes. Reactive astrocytes express surface molecules and produce various neurotrophic factors and cytokines. The latter in turn might modulate the production of recognition molecules by reactive astrocytes, allowing them to support post-lesional axonal regrowth. Although numerous recent articles have focused on cytokines and cell adhesion molecules, scant attention has been paid to reactive astrocytes. Reactive astrocytes should be considered a key element, like neurons, of a dynamic environment, thus forming with neurons a functional unit involved in homeostasis, plasticity and neurotransmission. Attempts are in progress to identify molecular markers for reactive astrocytes.
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Affiliation(s)
- J L Ridet
- INSERM U. 336, Université Montpellier II, Montpellier, France
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476
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von Koch CS, Zheng H, Chen H, Trumbauer M, Thinakaran G, van der Ploeg LH, Price DL, Sisodia SS. Generation of APLP2 KO mice and early postnatal lethality in APLP2/APP double KO mice. Neurobiol Aging 1997; 18:661-9. [PMID: 9461064 DOI: 10.1016/s0197-4580(97)00151-6] [Citation(s) in RCA: 244] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Amyloid precursor protein (APP) is a member of a larger gene family including amyloid precursor-like proteins (APLP), APLP2 and APLP1. To examine the function of APLP2 in vivo, we generated APLP2 knockout (KO) mice. They are of normal size, fertile, and appear healthy up to 22 months of age. We observed no impaired axonal outgrowth of olfactory sensory neurons following bulbectomy, suggesting against an important role for APLP2 alone in this process. Because APLP2 and APP are highly homologous and may serve similar functions in vivo, we generated mice with targeted APLP2 and APP alleles. Approximately 80% of double KO mice die within the first week after birth, suggesting that APLP2 and APP are required for early postnatal development. The surviving approximately 20% of double KO mice are 20-30% reduced in weight and show difficulty in righting, ataxia, spinning behavior, and a head tilt, suggesting a deficit in balance and/or strength. Adult double KO mice mate poorly, despite apparent normal ovarian and testicular development. Otherwise, double KO mice appear healthy up to 13 months of age. We conclude, that APLP2 and APP can substitute for each other functionally.
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Affiliation(s)
- C S von Koch
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205-2196, USA
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477
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Wolfer DP, Müller U, Stagliar M, Lipp HP. Assessing the effects of the 129/Sv genetic background on swimming navigation learning in transgenic mutants: a study using mice with a modified beta-amyloid precursor protein gene. Brain Res 1997; 771:1-13. [PMID: 9383002 DOI: 10.1016/s0006-8993(97)00673-2] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The Morris water maze is frequently used to screen mutant mice generated by gene targeting. Targeted ES-cells are often derived from 129/Sv or BALB/c mice, known as poor swimming navigation learners. After mating the founders with C57BL/6 mice, the F2 or F3 hybrid generation is typically used for behavioral testing. In hybrid 129/Sv x C57BL/6 mice, a modification of the betaAPP gene entails impaired swimming navigation learning. This is readily detected despite behavioral variability, because wild-type 129/Sv x C57BL/6 hybrids outperform either of the parental strains and provide a control sample with good baseline performance. However, after backcrossing to the 129/Sv(ev) strain, the mutation effects are no longer detectable, masked by the very poor performance of wild-type 129/Sv(ev) mice. We conclude that F2 and F3 generations of 129/Sv x C57BL/6 crosses provide a suitable genetic background for behavioral testing of transgenic mice, provided that the samples are large enough to compensate for genetic and epigenetic variability and provided that normal performance in the control group is verified by comparison against a large database of mice tested under identical conditions. Creating congenic lines by backcrossing to an inbred strain is unlikely to enhance the sensitivity of the Morris test. Backcrossing to 129/Sv(ev) may even reduce it.
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Affiliation(s)
- D P Wolfer
- Department of Anatomy, University of Zürich, Switzerland.
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478
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Theuring F, Thunecke M, Kosciessa U, Turner JD. Transgenic animals as models of neurodegenerative diseases in humans. Trends Biotechnol 1997; 15:320-5. [PMID: 9263480 DOI: 10.1016/s0167-7799(97)01066-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Neurodegenerative diseases are of major socioeconomic importance and represent an enormous challenge for the scientific and medical communities. Advances in molecular genetics during the past decade have begun to provide approaches for the establishment of animal models for these disorders using transgenic technology. Their analysis will lead to better understanding of disease pathogenesis and will be invaluable for the identification of novel diagnostic and therapeutic agents. With the current pace of genomic research, the generation of transgenic animal models, reproducing in full the pathology and symptoms of even complex disorders such as Alzheimer's disease, must now be considered achievable.
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Affiliation(s)
- F Theuring
- Medizinische Fakultät, Humboldt Universität, Institut für Pharmakologie und Toxikologie, Berlin, Germany
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479
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Wong PC, Zheng H, Chen H, Becher MW, Sirinathsinghji DJ, Trumbauer ME, Chen HY, Price DL, Van der Ploeg LH, Sisodia SS. Presenilin 1 is required for Notch1 and DII1 expression in the paraxial mesoderm. Nature 1997; 387:288-92. [PMID: 9153393 DOI: 10.1038/387288a0] [Citation(s) in RCA: 530] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Approximately 10% of cases of Alzheimer's disease are familial and associated with autosomal dominant inheritance of mutations in genes encoding the amyloid precursor protein, presenilin 1 (PS1) and presenilin 2 (PS2). Mutations in PS1 are linked to about 25% of cases of early-onset familial Alzheimer's disease. PS1, which is endoproteolytically processed in vivo, is a multipass transmembrane protein and is a functional homologue of SEL-12, a Caenorhabditis elegans protein that facilitates signalling mediated by the Notch/LIN-12 family of receptors. To examine potential roles for PS1 in facilitating Notch-mediated signalling during mammalian embryogenesis, we generated mice with targeted disruptions of PS1 alleles (PS1-/- mice). PS1-/- embryos exhibited abnormal patterning of the axial skeleton and spinal ganglia, phenotypes traced to defects in somite segmentation and differentiation. Moreover, expression of mRNA encoding Notch1 and Dll1 (delta-like gene 1), a vertebrate Notch ligand, is markedly reduced in the presomitic mesoderm of PS1-/- embryos compared to controls. Hence, PS1 is required for the spatiotemporal expression of Notch1 and Dll1, which are essential for somite segmentation and maintenance of somite borders.
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Affiliation(s)
- P C Wong
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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480
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Masliah E, Westland CE, Rockenstein EM, Abraham CR, Mallory M, Veinberg I, Sheldon E, Mucke L. Amyloid precursor proteins protect neurons of transgenic mice against acute and chronic excitotoxic injuries in vivo. Neuroscience 1997; 78:135-46. [PMID: 9135095 DOI: 10.1016/s0306-4522(96)00553-2] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The beta-amyloid protein precursor (APP) is well conserved across different species and may fulfill important physiological functions within the CNS. While high-level neuronal expression of amyloidogenic forms of human APP results in beta-amyloid production and neurodegeneration, lower levels of neuronal human APP expression in neurons of transgenic mice may primarily accentuate physiological functions of this molecule. To assess the neuroprotective potential of human APP in vivo, mice from seven distinct transgenic lines expressing different human APP isoforms from the neuron-specific enolase promoter were challenged with systemic kainate injections (n=30) or transgene-mediated glial expression of gp120 (n=32), an HIV-1 protein capable of inducing excitotoxic neuronal damage. To quantitate human APP-mediated neuroprotection. the area of neuropil occupied by presynaptic terminals and neuronal dendrites in the neocortex and hippocampus of each mouse was determined using laser scanning confocal microscopy of double-immunolabelled brain sections and computer-aided image analysis. Compared with gp120 singly transgenic controls, mice from three of three human APP751gp120 bigenic lines expressing the 751 amino acid form of human APP at low levels showed significant protection against degeneration of presynaptic terminals; two of these lines also showed significantly less damage to neuronal dendrites. Two of three human APP695/gp120 bigenic lines expressing human APP695 at low levels were protected against presynaptic and dendritic damage, whereas one low expressor line and a human APP695/gp120 bigenic line expressing human APP695 at higher levels showed no significant protection. In the corresponding human APP singly transgenic lines, overexpressing only specific human APP isoforms, significant protection against kainate-induced degeneration of presynaptic terminals and neuronal dendrites was found in two of three human APP751 lines and not in any of the four human APP695 lines tested. These results indicate that human APP can protect neurons against chronic and acute excitotoxic insults in vivo and that human APP isoforms differ in their neuroprotective potential, at least with respect to specific forms of neural injury. It is therefore possible that impairments of neuroprotective human APP functions or aberrant shifts in human APP isoform ratios could contribute to neurodegeneration.
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Affiliation(s)
- E Masliah
- Department of Neurosciences, University of California at San Diego, La Jolla 92093-0624, U.S.A
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481
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Abstract
In the past, structural changes in the brain with aging have been studied using a variety of animal models, with rats and nonhuman primates being the most popular. With the rapid evolution of mouse genetics, murine models have gained increased attention in the neurobiology of aging. The genetic contribution of age-related traits as well as specific mechanistic hypotheses underlying brain aging and age-related neurodegenerative diseases can now be assessed by using genetically-selected and genetically-manipulated mice. Against this background of increased demand for aging research in mouse models, relatively few studies have examined structural alterations with aging in the normal mouse brain, and the data available are almost exclusively restricted to the C57BL/6 strain. Moreover, many older studies have used quantitative techniques which today can be questioned regarding their accuracy. Here we review the state of knowledge about structural changes with aging in outbred, inbred, genetically-selected, and genetically-engineered murine models. Moreover, we suggest several new opportunities that are emerging to study brain aging and age-related neurodegenerative diseases using genetically-defined mouse models. By reviewing the literature, it has become clear to us that in light of the rapid progress in genetically-engineered and selected mouse models for brain aging and age-related neurodegenerative diseases, there is a great and urgent need to study and define morphological changes in the aging brain of normal inbred mice and to analyze the structural changes in genetically-engineered mice more carefully and completely than accomplished to date. Such investigations will broaden knowledge in the neurobiology of aging, particularly regarding the genetics of aging, and possibly identify the most useful murine models.
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Affiliation(s)
- M Jucker
- Gerontology Research Centre, Nathan W. Shock Laboratories, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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482
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Kaltschmidt B, Uherek M, Volk B, Baeuerle PA, Kaltschmidt C. Transcription factor NF-kappaB is activated in primary neurons by amyloid beta peptides and in neurons surrounding early plaques from patients with Alzheimer disease. Proc Natl Acad Sci U S A 1997; 94:2642-7. [PMID: 9122249 PMCID: PMC20142 DOI: 10.1073/pnas.94.6.2642] [Citation(s) in RCA: 469] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Amyloid beta peptide (A beta)-containing plaques are a hallmark of Alzheimer disease. Here, we show that the neurotoxic A beta, a major plaque component, is a potent activator of the transcription factor NF-kappaB in primary neurons. This activation required reactive oxygen intermediates as messengers because an antioxidant prevented A beta-induced NF-kappaB activation. Maximal activation of NF-kappaB was found with 0.1 microM A beta-(1-40) and 0.1 microM A beta-(25-35) fragments, making a role for NF-kappaB in neuroprotection feasible. Using an activity-specific mAb for the p65 NF-kappaB subunit, activation of NF-kappaB also was observed in neurons and astroglia of brain sections from Alzheimer disease patients. Activated NF-kappaB was restricted to cells in the close vicinity of early plaques. Our data suggest that the aberrant gene expression in diseased nervous tissue is at least in part due to A beta-induced activation of NF-kappaB, a potent immediate-early transcriptional regulator of numerous proinflammatory genes.
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Affiliation(s)
- B Kaltschmidt
- Institute of Biochemistry and Molecular Biology, Albert-Ludwigs-University, Freiburg, Germany.
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483
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Esler WP, Stimson ER, Ghilardi JR, Felix AM, Lu YA, Vinters HV, Mantyh PW, Maggio JE. A beta deposition inhibitor screen using synthetic amyloid. Nat Biotechnol 1997; 15:258-63. [PMID: 9062926 DOI: 10.1038/nbt0397-258] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The formation, growth, and maturation of brain amyloid "senile" plaques are essential pathological processes in Alzheimer's disease (AD) and key targets for therapeutic intervention. The process of in vitro deposition of A beta at physiological concentrations onto plaques in AD brain preparations has been well characterized, but is cumbersome for drug discovery. We describe here a high-through put screen for inhibitors of A beta deposition onto a synthetic template (synthaloid) of fibrillar A beta immobilized in a polymer matrix. Synthaloid is indistinguishable from plaques in AD brain (the natural template) in deposition kinetics, pH profile, and structure-activity relationships for both A beta analogs and inhibitors. Synthaloid, in contrast to current A beta aggregation screens, accurately predicted inhibitor potency for A beta deposition onto AD cortex preparations, validating its use in searching for agents that can slow the progression of AD and exposing a previously inaccessible target for drug discovery.
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Affiliation(s)
- W P Esler
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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484
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Mattson MP, Barger SW, Furukawa K, Bruce AJ, Wyss-Coray T, Mark RJ, Mucke L. Cellular signaling roles of TGF beta, TNF alpha and beta APP in brain injury responses and Alzheimer's disease. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1997; 23:47-61. [PMID: 9063586 DOI: 10.1016/s0165-0173(96)00014-8] [Citation(s) in RCA: 199] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
beta-Amyloid precursor protein (beta APP), transforming growth factor beta (TGF beta), and tumor necrosis factor-alpha (TNF alpha) are remarkably pleiotropic neural cytokines/neurotrophic factors that orchestrate intricate injury-related cellular and molecular interactions. The links between these three factors include: their responses to injury; their interactive effects on astrocytes, microglia and neurons; their ability to induce cytoprotective responses in neurons; and their association with cytopathological alterations in Alzheimer's disease. Astrocytes and microglia each produce and respond to TGF beta and TNF alpha in characteristic ways when the brain is injured. TGF beta, TNF alpha and secreted forms of beta APP (sAPP) can protect neurons against excitotoxic, metabolic and oxidative insults and may thereby serve neuroprotective roles. On the other hand, under certain conditions TNF alpha and the fibrillogenic amyloid beta-peptide (A beta) derivative of beta APP can promote damage of neuronal and glial cells, and may play roles in neurodegenerative disorders. Studies of genetically manipulated mice in which TGF beta, TNF alpha or beta APP ligand or receptor levels are altered suggest important roles for each factor in cellular responses to brain injury and indicate that mediators of neural injury responses also have the potential to enhance amyloidogenesis and/or to interfere with neuroregeneration if expressed at abnormal levels or modified by strategic point mutations. Recent studies have elucidated signal transduction pathways of TGF beta (serine/threonine kinase cascades), TNF alpha (p55 receptor linked to a sphingomyelin-ceramide-NF kappa B pathway), and secreted forms of beta APP (sAPP; receptor guanylate cyclase-cGMP-cGMP-dependent kinase-K+ channel activation). Knowledge of these signaling pathways is revealing novel molecular targets on which to focus neuroprotective therapeutic strategies in disorders ranging from stroke to Alzheimer's disease.
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Affiliation(s)
- M P Mattson
- Sanders-Brown Research Center on Aging, University of Kentucky, Lexington 40536-0230, USA.
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485
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486
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Bedell MA, Largaespada DA, Jenkins NA, Copeland NG. Mouse models of human disease. Part II: recent progress and future directions. Genes Dev 1997; 11:11-43. [PMID: 9000048 DOI: 10.1101/gad.11.1.11] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- M A Bedell
- Mammalian Genetics Laboratory, ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, Frederick, Maryland 21702-1201, USA
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487
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Müller DM, Mendla K, Farber SA, Nitsch RM. Muscarinic M1 receptor agonists increase the secretion of the amyloid precursor protein ectodomain. Life Sci 1997; 60:985-91. [PMID: 9121365 DOI: 10.1016/s0024-3205(97)00038-6] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Amyloid deposits in Alzheimer's disease are composed of amyloid beta-peptides (A beta) that are derived from the larger amyloid precursor protein (APP). Proteolytic APP processing is activity-dependent, and it can be regulated by muscarinic acetylcholine receptors. In particular, muscarinic m1 receptor subtypes increase cleavage within the A beta domain, followed by the release of the soluble APP ectodomain (APPs). In this study, we show that the m1-selective agonist talsaclidine concentration-dependently increased APPs release from both transfected human astrocytoma cell lines and rat brain slices. This increase was blocked by atropine. In contrast, the M2 antagonist BIBN 99 failed to increase APPs release, and decreased it at higher concentrations. These results show that talsaclidine can effectively modulate alpha-secretase processing of APP in human cell lines and in brain tissue. The data suggest that talsaclidine may be a useful candidate drug to modulate APP processing in Alzheimer's disease.
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Affiliation(s)
- D M Müller
- Center for Molecular Neurobiology, University of Hamburg, Germany
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488
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Nishimoto I, Okamoto T, Giambarella U, Iwatsubo T. Apoptosis in neurodegenerative diseases. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1997; 41:337-68. [PMID: 9204151 DOI: 10.1016/s1054-3589(08)61064-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- I Nishimoto
- Department of Pharmacology and Neurosciences, Keio University School of Medicine, Tokyo, Japan
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489
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APPL, the Drosophila member of the APP-family, exhibits differential trafficking and processing in CNS neurons. J Neurosci 1996. [PMID: 8764652 DOI: 10.1523/jneurosci.16-15-04638.1996] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The Drosophila Appl gene encodes a transmembrane protein that is expressed exclusively in neurons. Amino acid comparisons show that APPL protein is a member of the amyloid precursor protein (APP)-like family of proteins. Similar to mammalian APP-family proteins, APPL is synthesized as a transmembrane holoprotein and cleaved to release a large secreted amino-terminal domain. Using immunocytochemical methods, we have analyzed the distribution of APPL in the Drosophila CNS. Surprisingly, although APPL is present in all neuronal cell bodies, the neurophil shows sterotypic differential distribution. Double-labeling experiments with different neuronal markers were used to distinguish between APPL associated with neuronal processes or extracellular matrix. The distribution of APPL protein produced from transgenes encoding wild-type (APPL), secretion-defective (APPLsd), and constitutively secreted (APPLs) forms was analyzed in an Appl-deficient background to determine which APPL form is associated with different neuropil regions. We found that APPLsd protein is enriched where APPL immunoreactivity coincides with neuronal processes. In contrast, APPLs preferentially localizes to those parts of the neuropil that show a diffuse APPL signal that rarely colocalizes with processes, and thus seems to be a component of the extracellular matrix. These data indicate that proteolytic cleavage and trafficking of APPL is differentially regulated in different neuronal populations. Through metamorphosis, APPL is especially abundant in growing axons and in areas where synapses are forming. Interestingly, in adult brains, APPL protein is enriched in the mushroom bodies and to a lesser extent in the central complex, structures involved in learning and memory.
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490
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Storey E, Beyreuther K, Masters CL. Alzheimer's disease amyloid precursor protein on the surface of cortical neurons in primary culture co-localizes with adhesion patch components. Brain Res 1996; 735:217-31. [PMID: 8911660 DOI: 10.1016/0006-8993(96)00608-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Immunofluorescence on primary dissociated rat neuronal cultures (cortical, hippocampal, and cerebellar) and organotypic hippocampal cultures was used to investigate the pattern of distribution of cell-surface amyloid protein (APP). Antibodies directed against the extracellular (N-terminal) portion of APP or against the entire molecule, but not against the C-terminal portion, revealed a striking segmental pattern of immunoreactivity along both axons and dendrites of all neuronal types tested. The pattern first developed between 24 and 48 h in culture. The segments showed co-localization with beta 1-integrin and talin immunoreactivities, but not with GAP-43 or clathrin, indicating that they may mark adhesion patches. Confocal laser microscopy supported a surface location for the APP responsible for the segmented pattern on neurites, as did the reduction of segmental immunoreactivity after exposure to mu-calpain or trypsin. It is conjectured that APP may have a role in cell-substratum interactions in the medium term, during such events as synaptic plasticity and neurite stability during extension.
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Affiliation(s)
- E Storey
- Department of Pathology, University of Melbourne, Parkville, Victoria, Australia.
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491
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Sopher BL, Fukuchi K, Kavanagh TJ, Furlong CE, Martin GM. Neurodegenerative mechanisms in Alzheimer disease. A role for oxidative damage in amyloid beta protein precursor-mediated cell death. MOLECULAR AND CHEMICAL NEUROPATHOLOGY 1996; 29:153-68. [PMID: 8971693 DOI: 10.1007/bf02814999] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We have established a stably transformed human neuroblastoma cell line (MC65) that conditionally expresses a C-terminal derivative of the amyloid beta protein precursor (beta PP) termed S beta C (a fusion protein composed of the amino-17 and carboxyl-99 residues of beta PP). Conditional expression of S beta C (mediated by the withdrawal of tetracycline from the culture medium) induces pronounced nuclear DNA fragmentation and cytotoxicity in this cell line. These effects are enhanced by hyperoxygen and suppressed by hypooxygen and antioxidants. This cell line is relatively insensitive to the extracellular application of amyloid beta 25-35, and coculture experiments suggest that this cytotoxicity is mediated by an intracellular process. These findings suggest that the overexpression of the C-terminal domain of beta PP can disrupt normal cellular processes in these cells in such a way as to induce a directed (deoxyribonuclease-mediated) mechanism of cell death. This process appears to be modulated and/or mediated by a reactive oxygen specie(s) (ROS). Consistent with a role for ROS in the process of S beta C-mediated toxicity, we have found that the MC65 cell line is hypersensitive to oxidative stress and that it is this sensitivity that appears (at least in part) to underlie its susceptibility to S beta C.
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Affiliation(s)
- B L Sopher
- Department of Pathology, University of Washington, Seattle 98195-7470, USA
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492
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Storey E, Spurck T, Pickett-Heaps J, Beyreuther K, Masters CL. The amyloid precursor protein of Alzheimer's disease is found on the surface of static but not activity motile portions of neurites. Brain Res 1996; 735:59-66. [PMID: 8905170 DOI: 10.1016/0006-8993(96)00609-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have previously found that the amyloid precursor protein (APP) of Alzheimer's disease is present on the surface of rat cortical neurons in culture, in a segmental pattern which first becomes evident after 24 hours and is fully developed by five days. As APP has previously been reported to have a short half-life in neuronal cell lines, and has been shown to contain binding sites for various extracellular matrix components within its extracellular domain, we hypothesized that APP would be associated with portions of neurites undergoing rapid structural change, such as growth cones. To test this hypothesis, we observed selected neurons by video time-lapse differential interference microscopy on 24-hour-old primary rat neuronal cultures for up to 45 minutes, followed by fixation and immunocytochemistry to ascertain surface APP distribution on those same neurons. In contrast to our predictions, surface APP was not found on active portions of neurites, even if the activity produced no net translational movement. This result indicates that surface APP is actually associated with stable portions of neurites, a conclusion that tallies with other recent results showing that neuronal surface APP has a longer half-life than general cellular APP, and is associated with markers of adhesion patches, which themselves are relatively stable structures.
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Affiliation(s)
- E Storey
- Department of Pathology, University of Melbourne, Parkville, Victoria, Australia
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493
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Affiliation(s)
- D J Selkoe
- Department of Neurology and Program in Neuroscience, Harvard Medical School and Center for Neurologic Diseases, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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494
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Li ZW, Stark G, Götz J, Rülicke T, Gschwind M, Huber G, Müller U, Weissmann C. Generation of mice with a 200-kb amyloid precursor protein gene deletion by Cre recombinase-mediated site-specific recombination in embryonic stem cells. Proc Natl Acad Sci U S A 1996; 93:6158-62. [PMID: 8650236 PMCID: PMC39206 DOI: 10.1073/pnas.93.12.6158] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Gene disruptions and deletions of up to 20kb have been generated by homologous recombination with appropriate targeting vectors in murine embryonic stem (ES) cells. Because we could not obtain a deletion of about 200 kb in the mouse amyloid precursor protein gene by the classical technique, we employed strategies involving the insertion of loxP sites upstream and downstream of the region to be deleted by homologous recombination and elicited excision of the loxP-flanked region by introduction of a Cre expression vector into the ES cells. In the first approach, the loxP sequences were inserted in two successive steps and after each step, ES cell clones were isolated and characterized. Deletion of the loxP-flanked sequence was accomplished by introducing the cre gene in a third step. In the second approach, ES cells containing the upstream loxP cassette were electroporated simultaneously with the downstream loxP targeting vector and the Cre expression plasmid. ES cells were obtained that gave rise to chimeric mice capable of germ-line transmission of the deleted amyloid precursor protein allele.
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Affiliation(s)
- Z W Li
- Institut für Molekularbiologie der Universität Zürich, Switzerland
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495
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Yamatsuji T, Matsui T, Okamoto T, Komatsuzaki K, Takeda S, Fukumoto H, Iwatsubo T, Suzuki N, Asami-Odaka A, Ireland S, Kinane TB, Giambarella U, Nishimoto I. G protein-mediated neuronal DNA fragmentation induced by familial Alzheimer's disease-associated mutants of APP. Science 1996; 272:1349-52. [PMID: 8650548 DOI: 10.1126/science.272.5266.1349] [Citation(s) in RCA: 186] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Missense mutations in the 695-amino acid form of the amyloid precursor protein (APP695) cosegregate with disease phenotype in families with dominantly inherited Alzheimer's disease. These mutations convert valine at position 642 to isoleucine, phenylalanine, or glycine. Expression of these mutant proteins, but not of normal APP695, was shown to induce nucleosomal DNA fragmentation in neuronal cells. Induction of DNA fragmentation required the cytoplasmic domain of the mutants and appeared to be mediated by heterotrimeric guanosine triphosphate-binding proteins (G proteins).
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Affiliation(s)
- T Yamatsuji
- Cardiovascular Research Center, Massachusetts General Hospital, Department of Medicine, Harvard Medical School, Charlestown, MA 02129, USA
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496
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Chow N, Korenberg JR, Chen XN, Neve RL. APP-BP1, a novel protein that binds to the carboxyl-terminal region of the amyloid precursor protein. J Biol Chem 1996; 271:11339-46. [PMID: 8626687 DOI: 10.1074/jbc.271.19.11339] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
beta-Amyloid protein precursors (APPs, 695-770 amino acids) are the source of the 39-43 amino acid beta-amyloid (A beta) peptides that comprise diffuse and fibrillar deposits in the cerebral cortex and vasculature of Alzheimer's disease brains. A beta is thought to play a role in the pathogenesis of Alzheimer's disease, and, hence, considerable effort has been invested in defining the means by which A beta is generated from the APPs. Knowledge of the normal function of the APPs is sure to provide insights into the genesis and pathological persistence of A beta in Alzheimer's disease. APP is a cell surface protein with a large extracellular amino-terminal domain, a single transmembrane segment, and a short cytoplasmic tail. Its location and structural features characteristic of a receptor for signal transduction led us to search for potential effector proteins capable of binding and interacting with its cytoplasmic domain. Here, we report the cloning of a cDNA encoding one such protein. This ubiquitously expressed 59-kDa APP-binding protein, called APP-BP1, is 61% similar to a protein encoded by the Arabidopsis AXR1 gene, required for normal response to the hormone auxin, and is a relative of the ubiquitin activating enzyme E1.
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Affiliation(s)
- N Chow
- Molecular Neurogenetics Laboratory, McLean Hospital, Belmont, Massachusetts 02178, USA
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497
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Affiliation(s)
- B A Yankner
- Department of Neurology, Harvard Medical School, The Children's Hospital, Boston, Massachusetts 02115, USA
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498
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Hendriks L, Van Broeckhoven C. A beta A4 amyloid precursor protein gene and Alzheimer's disease. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 237:6-15. [PMID: 8620894 DOI: 10.1111/j.1432-1033.1996.0006n.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Alzheimer's disease is a senile dementia caused by progressive neurodegeneration of the central nervous system. One of the most prominent pathological characteristics is beta A4 amyloid deposition in senile plaques in the brain parenchyma and in cerebral blood vessels. beta A4 amyloid is processed from a larger integral membrane protein, the beta A4 amyloid precursor protein. Different pathogenic mutations in this protein have been detected in a small number of Alzheimer's disease families. Here functional implications of these mutations on the processing of the precursor protein and the beta A4 amyloid deposition will be discussed with respect to the pathogenesis of Alzheimer's disease and related disorders.
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Affiliation(s)
- L Hendriks
- Born-Bunge Foundation, University of Antwerp, Flemish Institute of Biotechnology, Department of Biochemistry, Belgium
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499
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Loring JF, Paszty C, Rose A, McIntosh TK, Murai H, Pierce JE, Schramm SR, Wymore K, Lee VM, Trojanowski JQ, Peterson KR. Rational design of an animal model for Alzheimer's disease: introduction of multiple human genomic transgenes to reproduce AD pathology in a rodent. Neurobiol Aging 1996; 17:173-82. [PMID: 8744398 DOI: 10.1016/0197-4580(95)02076-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A major obstacle to understanding the pathogenesis of Alzheimer's disease is the lack of easily studied animal models. Our approach is to apply transgenic methods to humanize mice and rats, employing methods that introduce large genomic transgenes, because this improves the level of transgene protein expression and the tissue specificity of expression. Our plan is to reproduce AD pathology in rodents by making them transgenic for several human proteins involved in AD. This report describes transgenic animal lines that we have produced, and summarizes our current approach and future plans. Two human genes known to be involved in AD pathology are the amyloid precursor protein (APP) and the E4 isoform of apolipoprotein E (apoE4). So far, we have produced and analyzed a transgenic line carrying the entire human APP gene cloned in a yeast artificial chromosome. We have also produced but not yet analyzed a mouse carrying the human apoE4 gene. Work is in progress to produce a transgenic line carrying a disease-causing mutation in the human APP gene. As we produce these animals, we are breeding them together, and also breeding them with a mouse line that lacks endogenous apoE, to produce an animal model carrying several human proteins whose interaction is believed to be instrumental in development of AD pathology. These transgenic animals will be useful for dissecting the biochemical and physiological steps leading to AD, and for development of therapies for disease intervention.
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Affiliation(s)
- J F Loring
- GenPharm International, Mountain View, CA 94043, USA
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500
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Aguzzi A, Brandner S, Marino S, Steinbach JP. Transgenic and knockout mice in the study of neurodegenerative diseases. J Mol Med (Berl) 1996; 74:111-26. [PMID: 8846161 DOI: 10.1007/bf01575443] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Accurate animal models are essential for detailed analysis of the mechanisms underlying human neurodegenerative diseases. In addition, they can offer useful paradigms for the development and evaluation of new therapeutic strategies. We review the most popular techniques for modification of the mammalian genome in vivo, and provide a critical evaluation of the available transgenic mouse models for several neurological conditions of humans, including prion diseases, human retroviral diseases, Alzheimer's disease, and motor neuron diseases.
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Affiliation(s)
- A Aguzzi
- Institute of Neuropathology, Department of Pathology, Zürich
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