From the laboratory of Dr. Ashley I. Bush, MD, PhD
Director, Laboratory for Oxidation Biology, Genetics and
Aging Unit,
Massachusetts General Hospital, Harvard University
-
Treatment with a copper-zinc
chelator markedly and rapidly inhibits beta-amyloid
accumulation in Alzheimer's disease transgenic
mice.
-
Cherny RA, Atwood CS, Xilinas ME, Gray DN,
Jones WD, McLean CA, Barnham KJ, Volitakis I,
Fraser FW, Kim Y, Huang X, Goldstein LE, Moir RD,
Lim JT, Beyreuther K, Zheng H, Tanzi RE, Masters
CL, Bush AI.
- J Biol Chem 2001 Jun 8;276(23):20466-73
-
Alzheimer's disease amyloid-beta
binds copper and zinc to generate an allosterically
ordered membrane-penetrating structure containing
superoxide dismutase-like subunits.
-
Curtain CC, Ali F, Volitakis I, Cherny RA, Norton
RS, Beyreuther K, Barrow CJ, Masters CL, Bush AI,
Barnham KJ.
- J Neurochem 2001 Mar;76(5):1509-20
-
Homocysteine potentiates copper-
and amyloid beta peptide-mediated toxicity in
primary neuronal cultures: possible risk factors in
the Alzheimer's-type neurodegenerative pathways.
-
White AR, Huang X, Jobling MF, Barrow CJ,
Beyreuther K, Masters CL, Bush AI, Cappai R.
- J Neurochem 2001 Mar;76(5):1509-20
-
Metal chelation as a potential
therapy for Alzheimer's disease.
-
Cuajungco MP, Faget KY, Huang X, Tanzi RE, Bush
AI.
- Ann N Y Acad Sci 2000;920:292-304
-
Redox-active iron mediates
amyloid-beta toxicity.
-
Rottkamp CA, Raina AK, Zhu X, Gaier E, Bush AI,
Atwood CS, Chevion M, Perry G, Smith MA.
- Free Radic Biol Med 2001 Feb 15;30(4):447-50
-
Oxidative processes in
Alzheimer's disease: the role of abeta-metal
interactions.
-
Lynch T, Cherny RA, Bush AI.
- Exp Gerontol 2000 Jul;35(4):445-51
-
Chelation and
intercalation:
complementary properties in a compound for the
treatment of Alzheimer's disease.
-
Cherny RA, Barnham KJ, Lynch T, Volitakis I, Li
QX, McLean CA, Multhaup G, Beyreuther K, Tanzi RE,
Masters CL, Bush AI.
- J Struct Biol 2000 Jun;130(2-3):209-16
-
Characterization of copper
interactions with alzheimer amyloid beta peptides:
identification of an attomolar-affinity copper
binding site on amyloid beta1-42.
-
Atwood CS, Scarpa RC, Huang X, Moir RD, Jones WD,
Fairlie DP, Tanzi RE, Bush AI.
- J Neurochem 2000 Sep;75(3):1219-33
-
Copper catalyzed oxidation of
Alzheimer Abeta.
-
Atwood CS, Huang X, Khatri A, Scarpa RC, Kim YS,
Moir RD, Tanzi RE, Roher AE, Bush AI.
- Cell Mol Biol (Noisy-le-grand) 2000
Jun;46(4):777-83
-
Alzheimer's disease, beta-amyloid
protein and zinc.
-
Huang X, Cuajungco MP, Atwood CS, Moir RD, Tanzi
RE, Bush AI.
- J Nutr 2000 May;130(5S Suppl):1488S-92S
-
Evidence that the beta-amyloid
plaques of Alzheimer's disease represent the redox-silencing
and entombment of abeta by zinc.
-
Cuajungco MP, Goldstein LE, Nunomura A, Smith MA,
Lim JT, Atwood CS, Huang X, Farrag YW, Perry G, Bush
AI.
- J Biol Chem 2000 Jun 30;275(26):19439-42
-
Cu(II) potentiation of alzheimer
abeta neurotoxicity. Correlation with cell-free
hydrogen peroxide production and metal reduction.
-
Huang X, Cuajungco MP, Atwood CS, Hartshorn MA,
Tyndall JD, Hanson GR, Stokes KC, Leopold M,
Multhaup G, Goldstein LE, Scarpa RC, Saunders AJ,
Lim J, Moir RD, Glabe C, Bowden EF, Masters CL,
Fairlie DP, Tanzi RE, Bush AI.
- J Biol Chem 1999 Dec 24;274(52):37111-6
-
The Alzheimer's disease amyloid
precursor protein modulates copper-induced toxicity
and oxidative stress in primary neuronal cultures.
-
White AR, Multhaup G, Maher F, Bellingham S,
Camakaris J, Zheng H, Bush AI, Beyreuther K, Masters
CL, Cappai R.
- J Neurosci 1999 Nov 1;19(21):9170-9
-
Copper levels are increased in
the cerebral cortex and liver of APP and APLP2
knockout mice.
-
White AR, Reyes R, Mercer JF, Camakaris J, Zheng
H, Bush AI, Multhaup G, Beyreuther K, Masters CL,
Cappai R.
- Brain Res 1999 Sep 25;842(2):439-44
-
-
The A beta peptide of Alzheimer's
disease directly produces hydrogen peroxide through
metal ion reduction.
-
Huang X, Atwood CS, Hartshorn MA, Multhaup G,
Goldstein LE, Scarpa RC, Cuajungco MP, Gray DN, Lim
J, Moir RD, Tanzi RE, Bush AI.
- Biochemistry 1999 Jun 15;38(24):7609-16
-
Differential effects of
apolipoprotein E isoforms on metal-induced
aggregation of A beta using physiological
concentrations.
-
Moir RD, Atwood CS, Romano DM, Laurans MH, Huang
X, Bush AI, Smith JD, Tanzi RE.
- Biochemistry 1999 Apr 6;38(14):4595-603
-
-
Role of free radicals and metal
ions in the pathogenesis of Alzheimer's disease.
-
Atwood CS, Huang X, Moir RD, Tanzi RE, Bush AI.
- Met Ions Biol Syst 1999;36:309-64
E-Mail Correspondence
with Dr. Bush Regarding the Role of Heavy Metals and
Aggregation of Amyloid
Date: Mon, 25 Jun 2001 19:33:02 -0400
To: "Affinity Labeling
Technologies, Inc."
From: Ashley Bush
Subject: Re: mercury
Dear Dr. Bush,
Do you believe clioquinol would be equally effective at removing Hg
from the brains of AD patients? Several studies have
suggested that this other sulfyhydryl reactive heavy
metal may also promote amyloid aggregation as well as
inhibit a number of key enzymes involved in the disease
process (see
http://www.altcorp.com/amalgampage.htm).
Sincerely, Curt Pendergrass Ph.D.
Dear Dr Pendergrass,
I visited Dr Haley a couple of years ago
while visiting Allan Butterfield. I am actually quite a
fan of your work, (and have lately started to get my Hg
fillings replaced). I didn't know that you had set up a
company. Very interesting. I actually do not know
whether clioquinol removes Hg. It doesn't work by
removing Cu and Zn from the brain, but by facilitating
equilibria that dissociate Zn and Cu from Abeta, and by
inhibiting hydrogen peroxide production which is
mediated by Cu. Whereas I accept the elevation of Hg in
AD as a distinct possibility, I find the
metallochemistry of Abeta as an SOD-like protein (it
definitely binds Zn and Cu exclusively in vivo), as a
more upstream biochemical argument. Certainly, though,
Hg accumulation would not help the antioxidant systems
cope with the hydrogen peroxide. A few thoughts. You may
wan to contact my commercial folk at www.pranabio.com
to investigate some joint work in this arena if you
think it is of interest. Thanks for your note.
All the best,
Ashley
Ashley I. Bush, MD, PhD
Director, Laboratory for Oxidation Biology, Genetics and
Aging Unit,
Massachusetts General Hospital,
Building 114, 16th Street
Charlestown, MA, 02129-4404, USA
Ph: 617-726-8244
Fax: 617-724-1823
Treatment with a copper-zinc
chelator markedly and rapidly inhibits beta-amyloid
accumulation in Alzheimer's disease transgenic
mice.
Cherny RA, Atwood CS, Xilinas ME, Gray DN,
Jones WD, McLean CA, Barnham KJ, Volitakis I,
Fraser FW, Kim Y, Huang X, Goldstein LE, Moir RD,
Lim JT, Beyreuther K, Zheng H, Tanzi RE, Masters
CL, Bush AI.
Department of Pathology, The University of
Melbourne and, The Mental Health Research
Institute of Victoria, Australia.
- Neuron 2001 Jun;30(3):665-76
Comment in:
Neuron. 2001 Jun;30(3):641-2
Inhibition of neocortical beta-amyloid (Abeta)
accumulation may be essential in an effective
therapeutic intervention for Alzheimer's disease
(AD). Cu and Zn are enriched in Abeta deposits in
AD, which are solubilized by Cu/Zn-selective
chelators in vitro. Here we report a 49% decrease
in brain Abeta deposition (-375 microg/g wet
weight, p = 0.0001) in a blinded study of APP2576
transgenic mice treated orally for 9 weeks with
clioquinol, an antibiotic and bioavailable Cu/Zn
chelator. This was accompanied by a modest
increase in soluble Abeta (1.45% of total cerebral
Abeta); APP, synaptophysin, and GFAP levels were
unaffected. General health and body weight
parameters were significantly more stable in the
treated animals. These results support targeting
the interactions of Cu and Zn with Abeta as a
novel therapy for the prevention and treatment of
AD.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11430801&dopt=Abstract
See comment on this study in WebMDH Health entitled:
Metal Remover Clears Alzheimer's Plaques in Mice
But Will It Improve Disease Symptoms? http://my.webmd.com/content/article/1728.81882
J Biol Chem 2001 Jun 8;276(23):20466-73
Alzheimer's disease amyloid-beta
binds copper and zinc to generate an allosterically
ordered membrane-penetrating structure containing
superoxide dismutase-like subunits.
Curtain CC, Ali F, Volitakis I, Cherny RA, Norton
RS, Beyreuther K, Barrow CJ, Masters CL, Bush AI,
Barnham KJ.
Biomolecular Research Institute, 343 Royal Parade,
Parkville, Victoria 3052, Australia.
Amyloid beta peptide (Abeta) is the major
constituent of extracellular plaques and
perivascular amyloid deposits, the pathognomonic
neuropathological lesions of Alzheimer's disease.
Cu(2+) and Zn(2+) bind Abeta, inducing aggregation
and giving rise to reactive oxygen species. These
reactions may play a deleterious role in the disease
state, because high concentrations of iron, copper,
and zinc have been located in amyloid in diseased
brains. Here we show that coordination of metal ions
to Abeta is the same in both aqueous solution and
lipid environments, with His(6), His(13), and
His(14) all involved. At Cu(2+)/peptide molar ratios
>0.3, Abeta coordinated a second Cu(2+) atom in a
highly cooperative manner. This effect was abolished
if the histidine residues were methylated at
N(epsilon)2, indicating the presence of bridging
histidine residues, as found in the active site of
superoxide dismutase. Addition of Cu(2+) or Zn(2+)
to Abeta in a negatively charged lipid environment
caused a conformational change from beta-sheet to
alpha-helix, accompanied by peptide oligomerization
and membrane penetration. These results suggest that
metal binding to Abeta generated an allosterically
ordered membrane-penetrating oligomer linked by
superoxide dismutase-like bridging histidine
residues.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11274207&dopt=Abstract
J Neurochem 2001 Mar;76(5):1509-20
Homocysteine potentiates copper-
and amyloid beta peptide-mediated toxicity in
primary neuronal cultures: possible risk factors in
the Alzheimer's-type neurodegenerative pathways.
White AR, Huang X, Jobling MF, Barrow CJ,
Beyreuther K, Masters CL, Bush AI, Cappai R.
Department of Pathology, The University of
Melbourne, Victoria, Australia. arwhite@unimelb.edu.au
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11238735&dopt=Abstract
Oxidative stress may have an important role in the
progression of neurodegenerative disorders such as
Alzheimer's disease (AD) and prion diseases.
Oxidative damage could result from interactions
between highly reactive transition metals such as
copper (Cu) and endogenous reducing and/or oxidizing
molecules in the brain. One such molecule,
homocysteine, a thiol-containing amino acid, has
previously been shown to modulate Cu toxicity in
HeLa and endothelial cells in vitro. Due to a
possible link between hyperhomocysteinemia and AD,
we examined whether interaction between homocysteine
and Cu could potentiate Cu neurotoxicity. Primary
mouse neuronal cultures were treated with
homocysteine and either Cu (II), Fe (II or III) or
Zn (II). Homocysteine was shown to selectively
potentiate toxicity from low micromolar
concentrations of Cu. The toxicity of homocysteine/Cu
coincubation was dependent on the ability of
homocysteine to reduce Cu (II) as reflected by the
inhibition of toxicity with the Cu (I)-specific
chelator, bathocuproine disulphonate. This was
supported by data showing that homocysteine reduced
Cu (II) more effectively than cysteine or methionine
but did not reduce Fe (III) to Fe (II). Homocysteine
also generated high levels of hydrogen peroxide in
the presence of Cu (II) and promoted Abeta/Cu-mediated
hydrogen peroxide production and neurotoxicity. The
potentiation of metal toxicity did not involve
excitotoxicity as ionotropic glutamate receptor
antagonists had no effect on neurotoxicity.
Homocysteine alone also had no effect on neuronal
glutathione levels. These studies suggest that
increased copper and/or homocysteine levels in the
elderly could promote significant oxidant damage to
neurons and may represent additional risk factor
pathways which conspire to produce AD or related
neurodegenerative conditions.
Metal chelation as a potential
therapy for Alzheimer's disease.
Cuajungco MP, Faget KY, Huang X, Tanzi RE, Bush
AI.
Laboratory for Oxidation Biology, Massachusetts
General Hospital, and Department of Psychiatry,
Harvard Medical School, Boston, Massachusetts 02115,
USA.
Ann N Y Acad Sci 2000;920:292-304
Alzheimer's disease is a rapidly worsening public
health problem. The current lack of effective
treatments for Alzheimer's disease makes it
imperative to find new pharmacotherapies. At
present, the treatment of symptoms includes use of
acetylcholinesterase inhibitors, which enhance
acetylcholine levels and improve cognitive
functioning. Current reports provide evidence that
the pathogenesis of Alzheimer's disease is linked to
the characteristic neocortical amyloid-beta
deposition, which may be mediated by abnormal metal
interaction with A beta as well as metal-mediated
oxidative stress. In light of these observations, we
have considered the development of drugs that target
abnormal metal accumulation and its adverse
consequences, as well as prevention or reversal of
amyloid-beta plaque formation. This paper reviews
recent observations on the possible etiologic role
of A beta deposition, its redox activity, and its
interaction with transition metals that are enriched
in the neocortex. We discuss the effects of metal
chelators on these processes, list existing drugs
with chelating properties, and explore the promise
of this approach as a basis for medicinal chemistry
in the development of novel Alzheimer's disease
therapeutics.
Redox-active iron mediates
amyloid-beta toxicity.
Rottkamp CA, Raina AK, Zhu X, Gaier E, Bush AI,
Atwood CS, Chevion M, Perry G, Smith MA.
Institute of Pathology, Case Western Reserve
University, Cleveland, OH 44106, USA.
Free Radic Biol Med 2001 Feb 15;30(4):447-50
While amyloid-beta toxicity is mediated by oxidative
stress and can be attenuated by antioxidants, the
actual biochemical mechanism underlying
neurotoxicity remains to be established. However,
since aggregated amyloid-beta can interact with
transition metals, such as iron, both in vitro and
in vivo, we suspected that bound iron might be the
mediator of toxicity such that holo- and apo-amyloid
would have differential effects on cellular
viability. Here we demonstrate that when amyloid-beta
is pretreated with the iron chelator deferoxamine,
neuronal toxicity is significantly attenuated while
conversely, incubation of holo-amyloid-beta with
excess free iron restores toxicity to original
levels. These data, taken together with the known
sequelae of amyloid-beta, suggest that the toxicity
of amyloid-beta is mediated, at least in part, via
redox-active iron that precipitates lipid
peroxidation and cellular oxidative stress.
Oxidative processes in
Alzheimer's disease: the role of abeta-metal
interactions.
Lynch T, Cherny RA, Bush AI.
Department of Pathology, The University of
Melbourne, and Neuropathology Laboratory, The Mental
Health Research Institute of Victoria, Vic. 3052,
Parkville, Australia.
Exp Gerontol 2000 Jul;35(4):445-51
Alzheimer's disease is characterized by signs of a
major oxidative stress in the neocortex and the
concomitant deposition of Amyloid beta (Abeta).
Abeta is a metalloprotein that binds copper, and is
electrochemically active. Abeta converts molecular
oxygen into hydrogen peroxide by reducing copper or
iron, and this may lead to Fenton chemistry.
Hydrogen peroxide is a freely permeable prooxidant
that may be responsible for many of the oxidative
adducts that form in the Alzheimer-affected brain.
The electrochemical activity of various Abeta
species correlates with the peptides' neurotoxicity
in cell culture, and participation in the
neuropathology of Alzheimer's disease. These
reactions present a novel target for Alzheimer
therapeutics.
Publication Types:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10959032&dopt=Abstract
Chelation
and intercalation: complementary properties in a
compound for the treatment of Alzheimer's disease.
Cherny RA, Barnham KJ, Lynch T, Volitakis I, Li
QX, McLean CA, Multhaup G, Beyreuther K, Tanzi RE,
Masters CL, Bush AI.
The Department of Pathology, The University of
Melbourne, Melbourne, Victoria, 3010, Australia.
J Struct Biol 2000 Jun;130(2-3):209-16
Selective application of metal chelators to
homogenates of human Alzheimer's disease (AD) brain
has led us to propose that the architecture of
aggregated beta-amyloid peptide, whether in the form
of plaques or soluble oligomers, is determined at
least in part by high-affinity binding of transition
metals, especially copper and zinc. Of the two
metals, copper is implicated in reactive oxygen
species generating reactions, while zinc appears to
be associated with conformational and antioxidant
activity. We tested the copper chelators trientine,
penicillamine, and bathophenanthroline for their
ability to mobilize brain Abeta as measured against
our benchmark compound bathocuproine (BC). All of
these agents were effective in solubilizing brain
Abeta, although BC was the most consistent across
the range of AD brain tissue samples tested.
Similarly, all of the copper chelators depleted
copper in the high-speed supernatants. BC alone had
no significant effect upon zinc levels in the
soluble fraction. BC extraction of brain tissue from
C100 transgenic mice (which express human Abeta but
do not develop amyloid) revealed SDS-resistant
dimers as Abeta was mobilized from the sedimentable
to the soluble fraction. NMR analysis showed that,
in addition to its copper chelating properties, BC
interacts with Abeta to form a complex independent
of the presence of copper. Such hybrid copper
chelating and "chain breaking" properties
may form the basis of a rational design for a
therapy for Alzheimer's disease. Copyright 2000
Academic Press.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10940226&dopt=Abstract
Characterization of copper
interactions with alzheimer amyloid beta peptides:
identification of an attomolar-affinity copper
binding site on amyloid beta1-42.
Atwood CS, Scarpa RC, Huang X, Moir RD, Jones WD,
Fairlie DP, Tanzi RE, Bush AI.
Laboratory for Oxidation Biology, Massachusetts
General Hospital and Harvard Medical School, Boston
02129-9142, USA.
J Neurochem 2000 Sep;75(3):1219-33
Cu and Zn have been shown to accumulate in the
brains of Alzheimer's disease patients. We have
previously reported that Cu(2+) and Zn(2+) bind
amyloid beta (Abeta), explaining their enrichment in
plaque pathology. Here we detail the stoichiometries
and binding affinities of multiple cooperative
Cu(2+)-binding sites on synthetic Abeta1-40 and
Abeta1-42. We have developed a ligand displacement
technique (competitive metal capture analysis) that
uses metal-chelator complexes to evaluate metal ion
binding to Abeta, a notoriously self-aggregating
peptide. This analysis indicated that there is a
very-high-affinity Cu(2+)-binding site on Abeta1-42
(log K(app) = 17.2) that mediates peptide
precipitation and that the tendency of this peptide
to self-aggregate in aqueous solutions is due to the
presence of trace Cu(2+) contamination (customarily
approximately 0.1 microM). In contrast, Abeta1-40
has much lower affinity for Cu(2+) at this site
(estimated log K(app) = 10.3), explaining why this
peptide is less self-aggregating. The greater
Cu(2+)-binding affinity of Abeta1-42 compared with
Abeta1-40 is associated with significantly
diminished negative cooperativity. The role of trace
metal contamination in inducing Abeta precipitation
was confirmed by the demonstration that Abeta
peptide (10 &mgr;M) remained soluble for 5 days
only in the presence of high-affinity
Cu(2+)-selective chelators.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10936205&dopt=Abstract
Copper catalyzed oxidation
of Alzheimer Abeta.
Atwood CS, Huang X, Khatri A, Scarpa RC, Kim YS,
Moir RD, Tanzi RE, Roher AE, Bush AI.
Massachusetts General Hospital East, Charlestown, MA
02129-9142, USA.
Cell Mol Biol (Noisy-le-grand) 2000 Jun;46(4):777-83
Abeta derived from amyloid plaques of Alzheimer's
disease-affected brain contain several oxidative
posttranslational modifications. In this study we
have characterized the amino acid content of human
amyloid-derived Abeta and compared it with that of
human synthetic Abeta subjected to metal-catalyzed
oxidation. Human amyloid derived Abeta has an
increased content of arginine (46%) and
glutamate/glutamine residues (28%), but a decreased
content of histidine residues (-32%) as compared to
the expected amino acid content. Incubation of
synthetic human Abeta with Cu(II), but not Fe(III),
in the presence of H2O2 similarly induced a decrease
in histidine residues (-79%), but also a decrease in
tyrosine residues (-28%). Our results suggest that
histidine and tyrosine are most vulnerable to metal
mediated oxidative attack, consistent with our
earlier findings that Cu coordinated via histidine
residues is redox competent. Our results suggest
that the loss of histidine residues in human amyloid-derived
Abeta may be a result of Cu oxidation, and that
unidentified post-translational mechanisms operate
to modify other amino acids of Abeta in vivo.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10875439&dopt=Abstract
Alzheimer's disease, beta-amyloid
protein and zinc.
Huang X, Cuajungco MP, Atwood CS, Moir RD, Tanzi
RE, Bush AI.
Laboratory for Oxidation Biology, Genetics and Aging
Unit, Department of Psychiatry, Harvard Medical
School, Massachusetts General Hospital, Charleston,
MA 02129, USA.
J Nutr 2000 May;130(5S Suppl):1488S-92S
Alzheimer's disease (AD) is characterized by amyloid
deposits within the neocortical parenchyma and the
cerebrovasculature. The main component of these
predominantly extracellular collections, Abeta,
which is normally a soluble component of all
biological fluids, is cleaved out of a ubiquitously
expressed parent protein, the amyloid protein
precursor (APP), one of the type 1 integral membrane
glycoproteins. Considerable evidence has indicated
that there is zinc dyshomeostasis and abnormal
cellular zinc mobilization in AD. We have
characterized both APP and Abeta as copper/zinc
metalloproteins. Zinc, copper and iron have recently
been reported to be concentrated to 0.5 to 1 mmol/L
in amyloid plaque. In vitro, rapid Abeta aggregation
is mediated by Zn(II), promoted by the alpha-helical
structure of Abeta, and is reversible with chelation.
In addition, Abeta produces hydrogen peroxide in a
Cu(II)/Fe(III)-dependent manner, and the hydrogen
peroxide formation is quenched by Zn(II). Moreover,
zinc preserves the nontoxic properties of Abeta.
Although the zinc-binding proteins apolipoprotein E
epsilon4 allele and alpha(2)-macroglobulin have been
characterized as two genetic risk factors for AD,
zinc exposure as a risk factor for AD has not been
rigorously studied. Based on our findings, we
envisage that zinc may serve twin roles by both
initiating amyloid deposition and then being
involved in mechanisms attempting to quench
oxidative stress and neurotoxicity derived from the
amyloid mass. Hence, it remains debatable whether
zinc supplementation is beneficial or deleterious
for AD until additional studies clarify the issue.
Publication Types:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10801964&dopt=Abstract
Evidence that the beta-amyloid
plaques of Alzheimer's disease represent the redox-silencing
and entombment of abeta by zinc.
Cuajungco MP, Goldstein LE, Nunomura A, Smith MA,
Lim JT, Atwood CS, Huang X, Farrag YW, Perry G, Bush
AI.
Laboratory for Oxidation Biology, Genetics and Aging
Unit, Massachusetts General Hospital, Charlestown,
Massachusetts 02129, USA.
J Biol Chem 2000 Jun 30;275(26):19439-42
Abeta binds Zn(2+), Cu(2+), and Fe(3+) in vitro, and
these metals are markedly elevated in the neocortex
and especially enriched in amyloid plaque deposits
of individuals with Alzheimer's disease (AD). Zn(2+)
precipitates Abeta in vitro, and Cu(2+) interaction
with Abeta promotes its neurotoxicity, correlating
with metal reduction and the cell-free generation of
H(2)O(2) (Abeta1-42 > Abeta1-40 >
ratAbeta1-40). Because Zn(2+) is redox-inert, we
studied the possibility that it may play an
inhibitory role in H(2)O(2)-mediated Abeta toxicity.
In competition to the cytotoxic potentiation caused
by coincubation with Cu(2+), Zn(2+) rescued primary
cortical and human embryonic kidney 293 cells that
were exposed to Abeta1-42, correlating with the
effect of Zn(2+) in suppressing Cu(2+)-dependent
H(2)O(2) formation from Abeta1-42. Since plaques
contain exceptionally high concentrations of Zn(2+),
we examined the relationship between oxidation (8-OH
guanosine) levels in AD-affected tissue and
histological amyloid burden and found a significant
negative correlation. These data suggest a
protective role for Zn(2+) in AD, where plaques form
as the result of a more robust Zn(2+) antioxidant
response to the underlying oxidative attack.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10801774&dopt=Abstract
Cu(II)
potentiation of alzheimer abeta neurotoxicity.
Correlation with cell-free hydrogen peroxide
production and metal reduction.
Huang X, Cuajungco MP, Atwood CS, Hartshorn MA,
Tyndall JD, Hanson GR, Stokes KC, Leopold M,
Multhaup G, Goldstein LE, Scarpa RC, Saunders AJ,
Lim J, Moir RD, Glabe C, Bowden EF, Masters CL,
Fairlie DP, Tanzi RE, Bush AI.
Laboratory for Oxidation Biology, Genetics and Aging
Unit, and Department of Psychiatry, Harvard Medical
School, Massachusetts General Hospital, Charlestown,
Massachusetts 02129, USA.
J Biol Chem 1999 Dec 24;274(52):37111-6
Oxidative stress markers as well as high
concentrations of copper are found in the vicinity
of Abeta amyloid deposits in Alzheimer's disease.
The neurotoxicity of Abeta in cell culture has been
linked to H(2)O(2) generation by an unknown
mechanism. We now report that Cu(II) markedly
potentiates the neurotoxicity exhibited by Abeta in
cell culture. The potentiation of toxicity is
greatest for Abeta1-42 > Abeta1-40 >>
mouse/rat Abeta1-40, corresponding to their relative
capacities to reduce Cu(II) to Cu(I), form H(2)O(2)
in cell-free assays and to exhibit amyloid
pathology. The copper complex of Abeta1-42 has a
highly positive formal reduction potential (
approximately +500-550 mV versus Ag/AgCl)
characteristic of strongly reducing cuproproteins.
These findings suggest that certain redox active
metal ions may be important in exacerbating and
perhaps facilitating Abeta-mediated oxidative damage
in Alzheimer's disease.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10601271&dopt=Abstract
The Alzheimer's disease amyloid
precursor protein modulates copper-induced toxicity
and oxidative stress in primary neuronal cultures.
White AR, Multhaup G, Maher F, Bellingham S,
Camakaris J, Zheng H, Bush AI, Beyreuther K, Masters
CL, Cappai R.
Department of Pathology, The University of
Melbourne, Parkville, 3052 Victoria, Australia.
J Neurosci 1999 Nov 1;19(21):9170-9
The amyloid precursor protein (APP) of Alzheimer's
disease can reduce copper (II) to copper (I) in a
cell-free system potentially leading to increased
oxidative stress in neurons. We used neuronal
cultures derived from APP knock-out (APP(-/-)) and
wild-type (WT) mice to examine the role of APP in
copper neurotoxicity. WT cortical, cerebellar, and
hippocampal neurons were significantly more
susceptible than their respective APP(-/-) neurons
to toxicity induced by physiological concentrations
of copper but not by zinc or iron. There was no
difference in copper toxicity between APLP2(-/-) and
WT neurons, demonstrating specificity for
APP-associated copper toxicity. Copper uptake was
the same in WT and APP(-/-) neurons, suggesting APP
may interact with copper to induce a localized
increase in oxidative stress through copper (I)
production. This was supported by significantly
higher levels of copper-induced lipid peroxidation
in WT neurons. Treatment of neuronal cultures with a
peptide corresponding to the human APP
copper-binding domain (APP142-166) potentiated
copper but not iron or zinc toxicity. Incubation of
APP142-166 with low-density lipoprotein (LDL) and
copper resulted in significantly increased lipid
peroxidation compared to copper and LDL alone.
Substitution of the copper coordinating histidine
residues with asparagines (APP142-166(H147N, H149N,
H151N)) abrogated the toxic effects. A peptide
corresponding to the zinc-binding domain
(APP181-208) failed to induce copper or zinc
toxicity in neuronal cultures. These data support a
role for the APP copper-binding domain in
APP-mediated copper (I) generation and toxicity in
primary neurons, a process that has important
implications for Alzheimer's disease and other
neurodegenerative disorders.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10531420&dopt=Abstract
Copper levels are increased in
the cerebral cortex and liver of APP and APLP2
knockout mice.
White AR, Reyes R, Mercer JF, Camakaris J, Zheng
H, Bush AI, Multhaup G, Beyreuther K, Masters CL,
Cappai R.
Department of Pathology, The University of
Melbourne, Parkville, Victoria, 3052, Australia.
Brain Res 1999 Sep 25;842(2):439-44
The pathological process in Alzheimer's disease (AD)
involves amyloid beta (Abeta) deposition and
neuronal cell degeneration. The neurotoxic Abeta
peptide is derived from the amyloid precursor
protein (APP), a member of a larger gene family
including the amyloid precursor-like proteins, APLP1
and APLP2. The APP and APLP2 molecules contain metal
binding sites for copper and zinc. The zinc binding
domain (ZnBD) is believed to have a structural
rather than a catalytic role. The activity of the
copper binding domain (CuBD) is unknown, however,
APP reduces copper (II) to copper (I) and this
activity could promote copper-mediated neurotoxicity.
The expression of APP and APLP2 in the brain
suggests they could have an important direct or
indirect role in neuronal metal homeostasis. To
examine this, we measured copper, zinc and iron
levels in the cerebral cortex, cerebellum and
selected non-neuronal tissues from APP (APP(-/-))
and APLP2 (APLP2(-/-)) knockout mice using atomic
absorption spectrophotometry. Compared with matched
wild-type (WT) mice, copper levels were
significantly elevated in both APP(-/-) and
APLP2(-/-) cerebral cortex (40% and 16%,
respectively) and liver (80% and 36%, respectively).
Copper levels were not significantly different
between knockout and WT cerebellum, spleen or serum
samples. There were no significant differences
observed between APP(-/-), APLP2(-/-) and WT mice
zinc or iron levels in any tissue examined. These
findings indicate APP and APLP2 expression
specifically modulates copper homeostasis in the
liver and cerebral cortex, the latter being a region
of the brain particularly involved in AD.
Perturbations to APP metabolism and in particular,
its secretion or release from neurons may alter
copper homeostasis resulting in increased Abeta
accumulation and free radical generation. These data
support a novel mechanism in the APP/Abeta pathway
which leads to AD.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10526140&dopt=Abstract
Aqueous dissolution of
Alzheimer's disease Abeta amyloid deposits by
biometal depletion.
Cherny RA, Legg JT, McLean CA, Fairlie DP, Huang
X, Atwood CS, Beyreuther K, Tanzi RE, Masters CL,
Bush AI.
Department of Pathology, The University of
Melbourne, Parkville, Victoria 3052, Australia.
J Biol Chem 1999 Aug 13;274(33):23223-8
Zn(II) and Cu(II) precipitate Abeta in vitro into
insoluble aggregates that are dissolved by metal
chelators. We now report evidence that these
biometals also mediate the deposition of Abeta
amyloid in Alzheimer's disease, since the
solubilization of Abeta from post-mortem brain
tissue was significantly increased by the presence
of chelators, EGTA, N,N,N',N'-tetrakis(2-pyridyl-methyl)
ethylene diamine, and bathocuproine. Efficient
extraction of Abeta also required Mg(II) and Ca(II).
The chelators were more effective in extracting
Abeta from Alzheimer's disease brain tissue than
age-matched controls, suggesting that metal ions
differentiate the chemical architecture of amyloid
in Alzheimer's disease. Agents that specifically
chelate copper and zinc ions but preserve Mg(II) and
Ca(II) may be of therapeutic value in Alzheimer's
disease.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10438495&dopt=Abstract
The A beta peptide of Alzheimer's
disease directly produces hydrogen peroxide
through
metal ion reduction.
Huang X, Atwood CS, Hartshorn MA, Multhaup G,
Goldstein LE, Scarpa RC, Cuajungco MP, Gray DN, Lim
J, Moir RD, Tanzi RE, Bush AI.
Laboratory for Oxidation Biology, Genetics and Aging
Unit, Massachusetts General Hospital, Charlestown
02129, USA.
Biochemistry 1999 Jun 15;38(24):7609-16
Oxidative stress markers characterize the
neuropathology both of Alzheimer's disease and of
amyloid-bearing transgenic mice. The neurotoxicity
of amyloid A beta peptides has been linked to
peroxide generation in cell cultures by an unknown
mechanism. We now show that human A beta directly
produces hydrogen peroxide (H2O2) by a mechanism
that involves the reduction of metal ions, Fe(III)
or Cu(II), setting up conditions for Fenton-type
chemistry. Spectrophotometric experiments establish
that the A beta peptide reduces Fe(III) and Cu(II)
to Fe(II) and Cu(I), respectively. Spectrochemical
techniques are used to show that molecular oxygen is
then trapped by A beta and reduced to H2O2 in a
reaction that is driven by substoichiometric amounts
of Fe(II) or Cu(I). In the presence of Cu(II) or
Fe(III), A beta produces a positive thiobarbituric-reactive
substance (TBARS) assay, compatible with the
generation of the hydroxyl radical (OH.). The
amounts of both reduced metal and TBARS reactivity
are greatest when generated by A beta 1-42 >>
A beta 1-40 > rat A beta 1-40, a chemical
relationship that correlates with the participation
of the native peptides in amyloid pathology. These
findings indicate that the accumulation of A beta
could be a direct source of oxidative stress in
Alzheimer's disease.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10386999&dopt=Abstract
Differential effects of
apolipoprotein E isoforms on metal-induced
aggregation of A beta using physiological
concentrations.
Moir RD, Atwood CS, Romano DM, Laurans MH, Huang
X, Bush AI, Smith JD, Tanzi RE.
Biochemistry 1999 Apr 6;38(14):4595-603
Genetics and Aging Unit, Department of Neurology,
Massachusetts General Hospital, Charlestown,
Massachusetts 02129-2060, USA.
The epsilon 4 allele of apolipoprotein E (APOE) has
been found to be a risk factor for late-onset
Alzheimer's disease (AD). While the pathogenic
mechanism of APOE in AD is not yet clear, APOE
isoforms appear to differentially influence the
aggregation of A beta, the principal component of
Alzheimer-associated beta-amyloid deposits. To date,
no data are available for the propensity of A beta
to aggregate in the presence of APOE under
conditions where these components are at
physiological concentrations (in cerebrospinal
fluid, APOE and A beta are approximately 100 nM and
approximately 5 nM, respectively). We employed a
novel in vitro filtration assay for detecting
zinc(II)- and copper(II)-induced aggregation of A
beta in solutions containing concentrations of the
peptide that are similar to those reported for human
cerebrospinal fluid. The potential for
resolubilization with EDTA and the relative
densities of zinc- and copper-induced A beta
aggregates were also compared. Zinc-induced A beta
aggregates were found to be denser and less easily
resolubilized than copper-induced precipitates.
Metal-induced aggregation of A beta was studied in
the presence of purified apolipoprotein E2,
apolipoprotein E3, and apolipoprotein E4 under
conditions that approximate the physiological
concentrations and ratios of these proteins. In the
presence of all three APOE isoforms, zinc-induced
aggregation of A beta was attenuated, while
precipitation with copper was enhanced. Consistent
with the increased risk for AD associated with the
epsilon 4 allele of APOE, metal-induced aggregation
of A beta was highest for both zinc and copper in
the presence of apolipoprotein E4. Our data are
consistent with a role for APOE as an in vivo
molecular chaperone for A beta.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10194381&dopt=Abstract
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Role of free radicals and metal
ions in the pathogenesis of Alzheimer's disease.
Atwood CS, Huang X, Moir RD, Tanzi RE, Bush AI.
Department of Psychiatry, Massachusetts General
Hospital, Harvard Medical School, Boston 02114, USA.
Met Ions Biol Syst 1999;36:309-64
Publication Types:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10093929&dopt=Abstract
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