Volume
6, Number 5, October 2004
Pages 461-467
Mar
Pérez, Raquel Cuadros, María J. Benítez, Juan S.
Jiménez (communicated by Jesus Avila)
Interaction of Alzheimer’s disease amyloid ß peptide
fragment 25-35 with tau protein, and with a tau peptide containing the
microtubule binding domain
Abstract: The interaction of amyloid ß (Aß) 25-35
with tau protein and with the peptide 1/2R (KVTSKCGSLGNIHHKPGGG), has
been investigated by chromatography, electron microscopy, and surface
plasmon resonance (SPR). Aß 25-35 comprises the minimum region of
Aß peptide that is able to aggregate into fibrils, and 1/2R contains
residues 307-325 from the tau region involved in microtubule binding.
The results of chromatography showed that Aß 25-35 induces the aggregation
of tau protein and of tau peptide 1/2R. Likewise, the results of electron
microscopy showed that Aß 25-35 increases the tau peptide polymerization
observed in the presence of polyanions like heparin. A decrease in Aß
25-35 aggregation induced by tau peptide was also observed by both techniques.
No direct interaction between tau protein immobilized on the sensor surface
and Aß25-35 could be detected by SPR. However, incubation of tau
protein at room temperature produced the loss of capability of this protein
for interacting with the active biosensor surface. The presence of Aß
25-35 during the incubation of tau protein makes more efficient this loss
of interacting capability with the sensor surface. These results clearly
indicate that Aß 25-35, the peptide region to which the cytotoxic
properties of Aß can be assigned, interacts with the peptide region
of tau protein involved in microtubule binding. This interaction produces
the aggregation of tau peptide and the concomitant disassembling of Aß
25-35, offering thus an explanation to the lack of co-localization of
neurofibrillary tangles and senile plaques in Alzheimer’s disease,
and suggesting the possibility that tau protein may have a protective
action by preventing Aß from adopting the cytotoxic, aggregated
form.
Pages 469-474
Jack
van Horssen, Rob A.I. de Vos, Ernst N.H. Jansen Steur, Guido David, Pieter
Wesseling, Robert M.W. de Waal, Marcel M. Verbeek
Absence of heparan sulfate proteoglycans in Lewy bodies and Lewy
neurites in Parkinson’s disease brains
Abstract: Alpha-Synuclein is the major constituent of Lewy bodies
and Lewy neurites in Parkinson’s disease (PD) and dementia with
Lewy bodies (DLB). Relatively little is known about the exact mechanism
of alpha-synuclein deposition and fibrillization in these alpha-synucleinopathies.
In order to better understand the pathogenesis of alpha-synucleinopathies
it is important to identify molecules that regulate the fibrillization
of alpha-synuclein. Since it has been demonstrated that heparan sulfate
proteoglycans (HSPGs) and glycosaminoglycans (GAGs) promote the conversion
of non-fibrillar amyloid ß-protein (Aß) into neurotoxic fibrillar
Aß in Alzheimer’s disease, they might also be involved in
alpha-synuclein aggregation. It was the aim of our study to examine the
distribution pattern of these macromolecules in PD brains and the possible
association with Lewy bodies and Lewy neurites. Although HSPGs clearly
colocalized with senile plaques, we were unable to identify HSPGs or GAGs
in Lewy bodies and Lewy neurites and therefore concluded that it is likely
that alpha-synuclein fibrillization and stabilization occurs independently
of the presence of HSPGs or GAGs.
Pages 475-482 Manuel
Menéndez
Pathological and clinical heterogeneity of presenilin 1 gene mutations
Abstract: The presenilins are two closely related genes which
implication in familial Alzheimer’s disease (FAD) is well known.
Presenilin 1 gene (PS1) mutations cause heterogeneous disorders and a
bibliographical review of atypical PS1-FAD cases allows us to describe
a great diversity of neuropathological and clinical variations and conclude
that most of them do not strongly depend on the genetic location of the
mutation so other genetic or epigenetic factors may be involved.
Pages 483-488
Hideo
Hara, Alon Monsonego, Katsutoshi Yuasa, Kayo Adachi, Xiao Xiao, Shin’ichi
Takeda, Keikichi Takahashi, Howard L. Weiner, Takeshi Tabira
Development of a safe oral Aß vaccine using recombinant
adeno-associated virus vector for Alzheimer’s disease.
Abstract: A new oral vaccine for Alzheimer's disease was developed
using recombinant adeno-associated virus vector carrying Aß cDNA
(AAV/Aß). Oral administration of the vaccine without adjuvant induced
the expression and secretion of Aß1-43 or Aß1-21 in the epithelial
cell layer of the intestine in amyloid precursor protein transgenic mice.
Serum antibody levels were elevated for more than six months, while T
cell proliferative responses to Aß was not detected. Brain Aß
burden was significantly decreased compared to the control without inflammatory
changes. This oral AAV/Aß vaccine seems to be promising for prevention
and treatment of Alzheimer’s disease.
Pages 489-495
Laura
A. Robertson, Kenneth L. Moya, Kieran C. Breen
The potential role of tau protein O-glycosylation in Alzheimer’s
disease
Abstract: Single O-linked N-acetylglucosamine (O-GlcNAc) sugar residues
have been can compete with phosphate groups to occupy specific sites on
certain nuclear and cytosolic proteins. Here we show that inhibiting cellular
kinase activities resulted in changes in protein O-glycosylation levels
in heat-stable cytoskeletal protein fractions derived from primary neuronal
cells. As increased phosphorylation of the microtubule-associated protein
tau is one of the pathological hallmarks of Alzheimer’s disease,
glycosylation may play an influential role in this process. We observed
a significant decrease in the protein O-GlcNAc glycosylation of a tau-enriched
cytoskeletal fraction generated from AD post-mortem brain samples as compared
with control, suggesting an inverse relationship between the two post-translational
modifications. Finally, cells transfected with the cDNA coding for O-GlcNAc
transferase (OGT) displayed altered tau phosphorylation patterns as compared
with control cells, suggesting that changes in tau glycosylation may influence
its phosphorylation state. The specificity of the changes in the phosphorylation
of individual amino acid residues provides evidence for a targeted O-glycosylation
of tau.
Pages 497-501 Liat
Ben-Avi, Ronen Durst, Shoshi Shpitzen, Eran Leitersdorf, Vardiella Meiner
Apo E genotyping: accurate, simple, high throughput method using
ABI Prism® SNaPshot™ Multiplex System
Abstract: Apolipoprotein E (apo E) is an essential constituent of several
plasma lipoproteins, and plays an important role in lipoprotein metabolism.
The apo E gene exhibits two common functional polymorphisms, producing
3 isoforms known to be associated with the risks of developing cardiovascular
disease and susceptibility to Alzheimer’s disease. Numerous different
methods have been established for determining the three apo E isoforms,
yet there are disadvantages and ambiguities associated with all of them.
We used a method adapted for multiplex automated primer extension analysis
by improving a commercially available protocol (SNaPshot™) and simultaneously
typing apo E single nucleotide polymorphisms (SNPs) encoding for isoforms
at codon 112 and 158. This protocol relies on the extension with fluorescent
dideoxyNTPs of a primer that ends one nucleotide 5’ of a given SNP
(minisequencing). Improvement of the method is achieved by incorporating
into the minisequencing reaction two pooled primers corresponding to both
apo E SNPs followed by analysis on an ABI PRisMS 310 DNA sequencer. We
found full concordance with genotypes determined using universal heteroduplex.
This method is readily available for many laboratories and is a simple,
unequivocal easy to use technique suitable for large amount of clinical
samples that may provide a significant improvement over previously reported
methods for apo E genotyping.
Pages 503-508
Thomas
A. Ala, Robert C. Doss, Christopher J. Sullivan (Communicated by J.
Riley McCarten)
Reversible dementia: A case of cryptococcal meningitis masquerading
as Alzheimer’s disease
Abstract: A 70-year-old man presented to us in 1994 with a three-year
history of worsening dementia. With the exceptions of a Mini-Mental State
exam score of 20 and an inability to tandem walk, his physical and neurological
examinations were normal. His past medical history revealed that in 1992
he had been evaluated at another institution for memory impairment and
bifrontal headaches. A spinal tap had been done in 1992 showing elevated
protein, reduced glucose, and a pleocytosis; his CSF fungal culture and
cryptococcal antigen test were negative. He subsequently was lost to follow-up,
and although his headaches had resolved, his mental status had continued
to worsen. In 1994 his CSF cryptococcal antigen was positive, and his
CSF fungal culture grew C. neoformans. He gradually improved with treatment
for cryptococcal meningitis (CM). With the exception of mild memory impairment,
in 2003 he and his family thought that his mental status had returned
to normal. This case emphasizes that: 1) CM should always be kept in the
differential diagnosis of dementia; 2) CM may be extremely insidious and
difficult to diagnose; and 3) if one is to rule out unequivocally all
possible reversible causes of dementia, one should perform a spinal tap.
Pages 509-514
David
A. Costa, Lars N.G.Nilsson, Kelly R. Bales, Steven M. Paul, Huntington
Potter
Apolipoprotein is required for the formation of filamentous amyloid,
but not for amorphous Aß deposition, in an AßPP/PS double
transgenic mouse model of Alzheimer’s disease
Abstract: To determine the role of apolipoprotein E (apoE) in
the deposition of different forms of Alzheimer amyloid deposit, we studied
mice expressing both mutant human amyloid ß-protein precursor (AßPP)
and presenilin 1 (PS1) that, in addition, were either normal or knocked-out
for apoE. By 7 months of age, extensive deposits of amorphous amyloid
ß (Aß) had developed equally in both lines, indicating that,
when present in high amounts, Aß alone is sufficient for such deposition
to occur. In contrast, filamentous, thioflavine S-positive amyloid deposition
in AßPP/PS mice was catalyzed at least 3000 fold by apoE. Electron
micrographs further illustrated the filamentous nature of Aß deposits
in mice expressing apoE. These and other behavior data indicate that the
primary function of apoE in Alzheimer’s disease is to promote the
polymerization of Aß into mature, beta pleated sheet filaments,
a process that is necessary for inducing cognitive decline. Thus, preventing
apoE from binding to Aß may prove to be an effective means of therapeutic
intervention.
Pages 515-525
Debra
Boyd-Kimball, Rukhsana Sultana, Hafiz Mohmmad-Abdul, D. Allan Butterfield
Rodent Aß(1-42) exhibits oxidative stress properties similar
to those of human Aß(1-42): Implications for proposed mechanisms
of toxicity
Abstract: Alzheimer’s disease is a neurodegenerative disorder
associated with aging and cognitive decline. Amyloid beta peptide (1-42)
[Aß(1-42)] is a primary constituent of senile plaques--a hallmark
of Alzheimer’s disease--and has been implicated in the pathogenesis
of the disease. Previous studies have shown that methionine residue 35
of Aß(1-42) may play a critical role in Aß(1-42)-mediated
oxidative stress and neurotoxicity. Several additional mechanisms of neurotoxicity
have been proposed, including the role of Cu(II) binding and reduction
to produce hydrogen peroxide and the role of peptide aggregation. It has
been reported that rodent Aß is less likely to form larger ß-sheet
structures, and consequently, large aggregates. As a consequence of the
lack of deposition of the peptide in rodent brain, rodent Aß has
been proposed to be non-toxic. Additionally, the sequence of the rodent
variety of Aß(1-42) contains three amino acid substitutions compared
to the human sequence. These substitutions include the shift of arginine
5, trysosine 10, and histidine 13 to glycine, phenylalanine, and arginine,
respectively. This shift in sequence within the Cu(II) binding region
of the peptide results in a decrease in the ability of the rodent Aß
peptide to reduce Cu(II) to Cu(I) compared to the human Aß peptide.
As a result of the effect of the amino acid variations on the ability
of the rodent peptide to reduce Cu(II) to Cu(I) compared to the human
peptide, the rodent Aß has been proposed to lack oxidative stress
properties. In this study, the oxidative stress and neurotoxic properties
of rodent Aß(1-42) [Aß1-42)Rat] were evaluated and compared
to those of human Aß(1-42). Both human Aß(1-42) and Aß(1-42)Rat
were found to have a significant effect on neuronal DNA fragmentation,
loss of neuritic networks, and cell viability. Aß(1-42) Rat was
found to cause a significant increase in both protein oxidation and lipid
peroxidation, similar to Aß(1-42), both of which were inhibited
by the lipid-soluble, chain breaking antioxidant vitamin E, suggesting
that reactive oxygen species play a role in the Aß-mediated toxicity.
Taken together, these results suggest that Cu(II) reduction may not play
a critical role in Aß(1-42)Rat-induced oxidative stress, and that
the oxidative stress exhibited by this peptide may be a consequence of
the presence of methionine 35, similar to the findings associated with
the native human Aß(1-42) peptide.
Pages 527-536
LuGuang
Luo, Edward G Stopa
Thyrotropin releasing hormone inhibits tau phosphorylation by
dual signaling pathways in hippocampal neurons
Abstract: Depletion of thyrotropin releasing hormone (TRH) gene
expression resulted in augmented Tau and glycosynthetase kinase-3ß
(GSK-3ß), in contrast, TRH administration resulted in decreases
of 75% in GSK-3ß and 90% in Tau phosphorylation in cultured rat
hippocampal neurons. To further study TRH regulation of tau phosphorylation,
immunoblotting was used to explore G-protein coupled TRH receptor activation
of the phosphokinase C (PKC) and phosphokinase A (PKA) signaling pathways.
TRH was found to rapidly activate PKA (2.5 fold in 10 min) while it suppressed
PKC (levels decreased by 85% vs. control) in hippocampal neurons. This
process was also discovered to be a cell type-specific response, as TRH
activated PKC in only hypothalamic neurons. Further investigation revealed
that the Src inhibitor Protein Phosphatase 2 (PP2, 50 uM) could block
TRH inhibition of PKC, GSK-3ß, and tau phosphorylation with no effects
on PKA. In addition, the PKC inhibitor GF109203 Bis (10 uM) was also able
to suppress TRH inhibition of GSK-3ß, leading to increased GSK-3ß
activity. Independent of these effects, inhibition of PKA by H89 (10 uM)
significantly blocked TRH inhibition of GSK-3ß. These data suggests
that both PKA and PKC are independently crucial to TRH’s effects
on GSK-3ß, and support the roles of two distinct pathways involving
suppression of PKC via the Src kinase and activation of PKA in mediating
TRH effects on GSK-3ß and tau. These dual signaling pathways between
TRH and tau may provide mechanisms for the precise regulation of tau phosphorylation
and dephosphorylation in neurons.
Pages 537-545
Transcript of Live
Discussion held at the Alzheimer
Research Forum
Axonal Transport Hypothesis Moves on to Implicate Presenilin
Pages 547-568
Proceedings of the 11th International Symposium, “New Frontiers
of Neurochemistry and Neurophysics on Diagnosis and Treatment of Neurological
Diseases,” with participation of the International Society
for Neurochemistry (ISN), in Memory of Vincenzo Lombardi (Martin, Slovakia,
December 4-7, 2003)
Page 569
Book Review: Psychiatry Highlights 2003-2004 Fast Facts Series by
Malcolm Lader. Health Press Ltd., Oxford, UK, 2004, 98 pp. Reviewed by
Alexandre de Mendonça.
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