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The Journal of Neuroscience, August 15, 2000, 20(16):6021-6029
Neuropathology in Mice Expressing Human -Synuclein
Herman
van der Putten1,
Karl-Heinz
Wiederhold1,
Alphonse
Probst2,
Samuel
Barbieri1,
Claudia
Mistl2,
Simone
Danner1,
Sabine
Kauffmann1,
Katja
Hofele1,
Will P. J. M.
Spooren1,
Markus A.
Ruegg4,
Shuo
Lin4,
Pico
Caroni3,
Bernd
Sommer1,
Markus
Tolnay2, and
Graeme
Bilbe1
1 Nervous System Research, Novartis Pharma Inc., CH
4002 Basel, Switzerland, 2 Institute for Pathology, CH 4003 Basel, Switzerland, 3 Friedrich Miescher Institute, CH 4058 Basel, Switzerland, and 4 Biozentrum, University of Basel,
CH 4056 Basel, Switzerland
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ABSTRACT |
The presynaptic protein -synuclein is a prime suspect for
contributing to Lewy pathology and clinical aspects of diseases, including Parkinson's disease, dementia with Lewy bodies, and a Lewy
body variant of Alzheimer's disease. -Synuclein accumulates in Lewy
bodies and Lewy neurites, and two missense mutations (A53T and A30P) in
the -synuclein gene are genetically linked to rare familial forms of
Parkinson's disease. Under control of mouse Thy1 regulatory
sequences, expression of A53T mutant human -synuclein in the nervous
system of transgenic mice generated animals with neuronal
-synucleinopathy, features strikingly similar to those observed in
human brains with Lewy pathology, neuronal degeneration, and motor
defects, despite a lack of transgene expression in dopaminergic neurons
of the substantia nigra pars compacta. Neurons in brainstem and motor
neurons appeared particularly vulnerable. Motor neuron pathology
included axonal damage and denervation of neuromuscular junctions in
several muscles examined, suggesting that -synuclein interfered with
a universal mechanism of synapse maintenance. Thy1 transgene expression
of wild-type human -synuclein resulted in similar pathological
changes, thus supporting a central role for mutant and wild-type
-synuclein in familial and idiotypic forms of diseases with neuronal
-synucleinopathy and Lewy pathology. These mouse models provide a
means to address fundamental aspects of -synucleinopathy and test
therapeutic strategies.
Key words:
transgenic mice; -synuclein; wild-type; A53T mutant; Lewy pathology; Parkinson's disease; dementia with Lewy bodies; ubiquitination
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INTRODUCTION |
Idiopathic Parkinson's disease
(PD), dementia with Lewy bodies (DLB), and a Lewy body variant of
Alzheimer's disease (LBVAD) are characterized pathologically by
proteinaceous inclusions in neurons commonly referred to as Lewy
pathology in postmortem brain tissue samples (Forno, 1996 ; Ince
et al., 1998 ; Irizarry et al., 1998 ; Spillantini et al., 1998 ; Takeda
et al., 1998 ; Braak et al., 1999 ). The inclusions occur in the
dystrophic (Lewy) neurites that constitute an important part of the
pathology of PD and DLB (Irizarry et al., 1998 ; Spillantini et al.,
1998 ; Braak et al., 1999 ), in neuronal perikarya (Lewy bodies)
(Forno, 1996 ; Spillantini et al., 1997 ; Wakabayashi et al., 1997 ; Baba
et al., 1998 ; Ince et al., 1998 ; Irizarry et al., 1998 ; Mezey et al.,
1998 ; Spillantini et al., 1998 ; Takeda et al., 1998 ; Braak et al.,
1999 ), and occasionally extracellularly (Den Hartog and Bethlem,
1960 ).
-Synuclein is the major constituent of Lewy bodies and Lewy neurites
(Spillantini et al., 1997 ; Wakabayashi et al., 1997 ; Baba et al., 1998 ;
Ince et al., 1998 ; Irizarry et al., 1998 ; Mezey et al., 1998 ;
Spillantini et al., 1998 ; Takeda et al., 1998 ; Arai et al., 1999 ; Braak
et al., 1999 ; Giasson et al., 2000 ). To lesser and varying degrees,
these inclusions contain ubiquitin (Gai et al., 1995 ), neurofilament
proteins (Forno, 1996 ; Ince et al., 1998 ; Takeda et al., 1998 ),
ubiquitin C-terminal hydrolase (Lowe et al., 1990 ), proteosomal
subunits (Li et al., 1997 ), and a variety of other antigenic
determinants (Pollanen et al., 1993 ). -Synuclein immunoreactivity is
the most sensitive and reliable diagnostic for Lewy-type pathology
(Forno, 1996 ; Spillantini et al., 1997 ; Wakabayashi et al., 1997 ; Baba
et al., 1998 ; Ince et al., 1998 ; Irizarry et al., 1998 ; Mezey et al.,
1998 ; Spillantini et al., 1998 ; Takeda et al., 1998 ; Braak et al.,
1999 ).
Lewy pathology in neurons appears to be central and may contribute
mechanistically to their dysfunction and degeneration in disease.
Altogether, the distribution of -synuclein-containing inclusions in
disorders with Lewy pathology, the discovery of two mutations in the
-synuclein gene linked to early-onset familial PD (Polymeropoulos et
al., 1997 ; Krüger et al., 1998 ), the ability of the protein to
self-aggregate (Conway et al., 1998 , 2000 ; Giasson et al., 1999 ; Narhi
et al., 1999 ; Wood et al., 1999 ), and recent findings in
vivo in transgenic flies (Feany and Bender, 2000 ) and mice
(Masliah et al., 2000 ) are supporting a central role for -synuclein
in the pathophysiology of diseases with Lewy pathology.
Here, we demonstrate pathology with neuronal degeneration and
accompanying motor deficits in mice, by neuronal expression of the A53T
mutant of human -synuclein or its wild-type counterpart. -Synuclein-encoding cDNAs were under control of mouse Thy1
regulatory sequences (Lüthi et al., 1997 ; Sturchler-Pierrat et
al., 1997 ; Wiessner et al., 1999 ) that produced reliably
neuron-specific expression and high protein levels in many central
neurons of the mouse nervous system.
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MATERIALS AND METHODS |
Transgenic mice. Wild-type human -synuclein cDNA
(396 bp) was PCR amplified (2 min, 93°C; three cycles of 15 sec,
93°C; 30 sec, 55°C; 30 sec, 72°C; two cycles of 15 sec, 93°C;
30 sec, 60°C; 30 sec, 72°C; and 30 cycles of 15 sec, 93°C; 30 sec, 66°C; 30 sec, 72°C; oligonucleotides, cgacgacagtgtggtgtaaaggaa
and tgggcacattggaactgagcactt) from 20 ng of human brain cDNA (Clontech,
Palo Alto, CA) and cloned into pMOSBlue (Amersham Pharmacia
Biotech, Little Chalfont, UK). The A53T mutation was
introduced using PCR oligonucleotide-directed mutagenesis (Stratagene,
La Jolla, CA; 30 sec, 93°C; 14 cycles of 30 sec, 93°C; 1 min,
55°C; 13 min, 68°C; oligonucleotides, agtggtgcatggtgtgacaacagtggctgaga and tctcagccactgttgtcacaccatgcaccact). The identity of wild-type and mutant cDNA was confirmed by sequencing and the corresponding blunted (Klenow) cDNAs
(NdeI-SmaI) inserted into the blunted
(XhoI site) Thy1 cassette (Lüthi et al., 1997 ; Sturchler-Pierrat et al., 1997 ; Wiessner et al., 1999 ). For
microinjection, linear NotI DNA fragments comprising
transgene without plasmid vector sequences were isolated. Injection was
into homozygous C57BL/6 mouse eggs. Genotyping was performed by PCR
(oligonucleotides were identical to those used for cloning the human
-synuclein cDNA; 5 min, 95°C; 30 cycles of 30 sec, 95°C; 1 min,
60°C; 1 min, 72°C; 10 min, 72°C) using column-purified (Qiagen,
Hilden, Germany) tail DNA.
Northern blot analysis. Northern blot analysis was performed
with total brain RNA (TriZol method; 10 µg loaded per gel lane). Probes were either 364 (Fig.
1A, probe A)
or 111 bp of the human -synuclein cDNA (Fig. 1A,
probe B; unlike probe A, probe B lacks homology to cDNAs encoding -synuclein-related family members) (Lavedan, 1998 ), or 600 bp of mouse Thy1 3' untranslated
sequences (Lüthi et al., 1997 ) (Fig. 1A,
probe C). Standard procedures were used.

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Figure 1.
Transgene expression. A, Schematic
representation of the transgene. Roman numerals
refer to exons in the endogenous murine Thy1 gene. Boxes
represent a complete -synuclein coding cDNA probe
(A), a C-terminal 111 bp -synuclein cDNA
probe (B), and a Thy1 3' untranslated region
probe (C) (Lüthi et al., 1997 ).
Arrows represent PCR primers for genotyping.
B, Northern blot analysis of 10 µg of total brain RNA
using probe A and brain RNA of a C57BL/6 nontransgenic mouse
(lane 1), a line 9813 mouse (lane 2), a
line 9956 mouse (lane 3), and the single transgenic male
of line 9832 (lane 4). The
arrowhead refers to the transgene mRNA, and the
horizontal bar marks the position of endogenous mouse
-synuclein mRNA. C, Immunoblot analysis showing
increased levels of -synuclein protein in brain homogenates of a
representative mouse of each of the lines 9956 (lane 1),
9813 (lane 2), the single F1 male of line 9832 (lane 3), and C57BL/6 (lane 4).
The polyclonal rabbit antibody used (Chemicon) detects both mouse and
human -synuclein protein. D, Immunoblot using the
antibody LB509 (specifically detects human but not the mouse
-synuclein protein; Zymed) and line 9956 (lane 1),
line 9813 (lane 2), and C57BL/6 (lane 3).
E, F, In situ
hybridization in sagittal brain sections of a line 9813 mouse
(E) and a C57BL/6 mouse (F)
using 35S-labeled cRNA corresponding to probe A
(A). G, H, In
situ hybridization in horizontal brain sections of a line 9813 mouse (G) and a C57BL/6 mouse
(H) using 35S-labeled cRNA
corresponding to probe B (A).
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Immunoblot analysis. For Western blot analysis, 14,000 × g supernatant fractions were used of half-brain
homogenates [homogenized in 2 ml of E-buffer (50 mM Tris-HCl, pH7.4, 1% NP-40, 0.25%
Na-deoxycholate, 150 mM NaCl, 1 mM EDTA, and a cocktail of protease inhibitors (Boehringer Mannheim, Mannheim, Germany) and left on ice for 30 min].
Fifteen, 25, or 50 µg of protein was loaded per lane and separated on
15% SDS-PAGE. After blotting and blocking nonspecific binding,
membranes were incubated with rabbit anti- -synuclein polyclonal
antibody (1:1000; AB5038; Chemicon, Temecula, CA), followed by
alkaline phosphatase (AP)-conjugated anti-rabbit IgG (1:50,0000; AO418; Sigma, St. Louis, MO), or the
anti-human- -synuclein-specific antibody LB509 (1:5000; Zymed, San
Francisco, CA), followed by AP-conjugated anti-mouse IgG1 (1:40,000;
Sigma) and chemiluminescent detection (Clontech).
In situ hybridizations. The spatial distribution pattern of
transgene versus endogenous -synuclein expression was determined by
in situ hybridization (Wiessner et al., 1999 ). cRNA was
transcribed using T7-RNA polymerase and a 364 bp cDNA template
(complete human -synuclein coding region) or a 111 bp cDNA template
(corresponding to the region encoding amino acids 103-140 of human
-synuclein).
Immunocytochemistry. Mice (aged 3.8-6 months) were injected
with pentobarbital (50 mg/ml Nembutal; Abbott laboratories, North Chicago, IL) and perfused transcardially with 0.01 M PBS, followed by 4% paraformaldehyde in
PBS. One brain hemisphere, spinal cord, and hind limb muscle were
embedded in paraffin and cut as 4-µm-thick sections. Vibratome
sections (25 µm) were cut from the other hemisphere for
free-floating immunocytochemical staining using anti- -synuclein mouse monoclonal antibody (1:500; S63320; Transduction Laboratories, Lexington, KY), biotinylated anti-mouse IgG (1:500; E0464; Dako, Copenhagen, Denmark), and the avidin-biotin peroxidase method (Elite
standard kit SK6100; Vector Laboratories, Burlingame, CA). In addition,
the following antibodies were used: AT8 monoclonal, which detects
paired helical filament and hyperphosphorylated tau (1:1000; BR-003;
Innogenetics, Zwijndrecht, Belgium); neurofilament 200 kDa-specific
monoclonal, detecting normal and phosphorylated neurofilaments (1:100;
NCL-NF200; Novocastra, Newcastle, UK); neurofilament M and H monoclonal
(phophorylated forms; 1:500; MAB 1592; Chemicon). Stainings (including
also Congo red and thioflavine S) were as described by
Sturchler-Pierrat et al. (1997) . Deparaffinized sections were used for
Campbell-Switzer silver staining (Campbell et al., 1987 ),
Holmes-Luxol staining (Holmes, 1943 ), and immunostaining with rabbit
anti-ubiquitin Ig fraction (1:200; Z0458; Dako), rabbit anti-glial
fibrillary acidic protein (GFAP) Ig fraction (1:500; Z0334; Dako),
anti-phosphotyrosine mouse monoclonal antibody (1:1500; P3300; Sigma),
and anti-human -synuclein-specific mouse monoclonal antibody (LB509;
1:2000; 18-0215; Zymed) (Baba et al., 1998 ; Jakes et al., 1999 ).
Antigenity was enhanced by treating paraffin sections with concentrated
formic acid for 5 min and microwave heating at 90°C for 60 min before
incubation with anti- -synuclein, microwave heating at 90°C for 30 min before anti-GFAP and anti-phosphotyrosine, and pronase treatment
(37°C, 30 min) before anti-ubiquitin. Nonspecific binding sites were
blocked using normal serum. Bound antibody was visualized using the
avidin-biotin peroxidase method (Elite standard kit SK6100; Vector
Laboratories) and DAB substrate (1718096; Boehringer Mannheim) or
Vector Laboratories AEC substrate (SK-4200). Immunostaining and
confocal analysis of neurofilament and synaptophysin at neuromuscular
junctions (NMJs) were as follows. Mice were killed by
anesthesia. Extensor digitorum longus (EDL) and soleus muscles were
excised and stained with Alexa Fluor 488-labeled -bungarotoxin (1:1000 in F-15 medium; Molecular Probes, Eugene, OR) for 2 hr at
4°C, followed by several rinses with PBS. Muscles then fixed with
cold methanol ( 20°C) and permeabilized with blocking solution (PBS
containing 5% horse serum, 1% BSA, 1% Triton X-100, and 0.1% sodium
azide) for 2 hr at 4°C. Tissue was subsequently incubated with
primary antibodies against either neurofilament (1:500 in blocking
solution; Sigma) or synaptophysin (1:200 in blocking solution; Dako)
and was incubated for 40 hr at 4°C. After several rinses with PBS,
muscles were incubated with Cy3-labeled goat anti-rabbit IgG (1:1000 in
blocking solution; Jackson ImmunoResearch, West Grove, PA) overnight at
4°C. The muscles were thoroughly rinsed with PBS and mounted on glass
slides using Citifluor (Plano). The tissue was examined with a confocal
microscope (model TCS NT; Leica, Nussloch, Germany).
Immunoelectron and electron microscopy. For immunoelectron
microscopy, transgenic and wild-type C57BL/6 mice were perfused transcardially with a mixture of 1.5% picric acid, 0.1%
glutaraldehyde, and 4% paraformaldehyde in 0.1 M
phosphate buffer, pH 7.4. Vibratome sections were stained free-floating
with antibody to -synuclein (LB509; 1:2000) dehydrated in ascending
series of ethanol and acetone, and flat-embedded between glass slide
and coverslips in Embed-812 (Electron Microscopy Sciences, Fort
Washington, PA). Fragments of the spinal cord were then dissected out
and ultrathin sections were cut from the tissue surface, and these were
mounted on copper grids and analyzed with a Zeiss (Oberkochen, Germany) EM900 microscope. For conventional electron microscopy, mice were anesthetized and perfused transcardially with cold saline,
followed by 4% paraformaldehyde and 0.1% glutaraldehyde in 0.1 M cacodylate buffer. Small tissue blocks
were cut out from brainstem and spinal cord, immersion-fixed for 12 hr
at 4°C in the same buffer, and epoxy-embedded, and ultrathin sections
were prepared and placed on 200-mesh copper grids for staining with
uranyl acetate and lead citrate.
Silver-esterase staining of neuromuscular junctions. The
combined silver-esterase technique was applied on gastrocnemius muscle. This muscle was freshly dissected and, after a brief wash in 10 mM EDTA in PBS, the tissue was mounted for
cryostat sectioning and cut (50 µm longitudinal sections). Slides
were rinsed in 80 mM EDTA in PBS before mounting
sections. Sections were dried for 30-120 min at 37°C, immersed in
sodium sulfate (29%) for 3 min, washed in H2O,
and incubated for 25 min at 37°C in acetylcholinesterase staining
solution (Pestronk and Drachman, 1978 ). After washing in
H2O, sections were dehydrated in 70 and 100%
ethanol, respectively, for 1-2 min each. Next, sections were fixed in
buffered formol saline (Pestronk and Drachman, 1978 ) for 30 min at room
temperature, washed in H2O, and pretreated for 30 min at 37°C in 10% chloral hydrate (w/v) containing 1% pyridine
(v/v). After washing in H2O, the sections were
incubated in a freshly prepared solution of 20% silver nitrate
containing 1% cupric sulfate. Calcium carbonate was added to each
slide separately. Incubation was for 40 min at 37° before discarding
the solution, washing in H2O, and incubation for
10 sec and 3-5 min, respectively, in a bath of 1% hydroquinone and
5% sodium sulfite. After washing in H2O,
sections were fixed (2-5 min) in 5% sodium thiosulfate, washed (in
H2O), toned for 5 min in 0.2% sodium
tetrachloroaureate (after adding freshly a drop of glacial acetic
acid), washed (in H2O), immersed in 1% oxalic
acid for 20-120 sec, washed (in H2O), fixed
again in 5% sodium thiosulfate, washed (in H2O),
dehydrated in ethanol, air dried, rinsed in xylene, air dried, and mounted.
Rotating rod. The mice were trained twice daily and on two
successive days to stay on a rotating rod (Technical and Scientific Equipment, Bad Homburg, Germany) for 150 sec (speed of 12 rpm). Subsequently, the animals were tested on the rotating rod once weekly,
three times and at three different speeds (i.e., 12, 24, and 36 rpm).
The cutoff time used for measuring the endurance performance in all of
these experiments was 60 sec. The plotted mean endurance performance on
a particular test day was the mean of the three performances at the
given speed. Statistical evaluation of the data were using repeated
measures ANOVA.
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RESULTS |
Six transgenic C57BL/6 lines were produced, each expressing a
Thy1 SNA53T transgene to a different level. The two lines described in this report (9813 and 9956) expressed transgene mRNA levels (Fig.
1B, mRNA levels were 9832 > 9813 > 9956 as shown for three lines; others not shown) that each resulted in
increased levels of -synuclein protein in brain (Fig. 1C,
antibody cross-reacting with mouse and human -synuclein; Fig.
1D, antibody detecting only human -synuclein). In
both lines, transgene expression occurred in neurons throughout the
telencephalon, brainstem, and spinal cord, as shown in a representative
sagittal section of a mouse brain of line 9813 (Fig.
1E). In situ hybridization with a cRNA probe that corresponds to the full-length coding sequence of human -synuclein (Fig. 1A, probe A), shows
the transgene mRNA expression pattern superimposed on that of
endogenous mouse -synuclein, the latter being apparent mainly in the
telencephalon (Fig. 1F). Transgene expression pattern
was also monitored specifically using a cRNA probe that corresponds to
111 bp encoding the C-terminal 37 amino acids of human -synuclein
(Fig. 1A, probe B). This probe is 87.5%
homologous to mouse cDNA but has nucleotide differences occurring every
10-20 bp. As a result and as shown in a pair of horizontal sections,
this probe detects no signal above background (as verified also by
Northern blot analysis; data not shown) in the nontransgenic C57BL/6
mouse brain (Fig. 1H), whereas the signal in the
transgenic brain reflects specifically the transgene expression pattern
(Fig. 1G).
In all of the mice of lines 9813 and 9956, we observed an early-onset
(>3 weeks of age) and a progressive decline of motor performance. A
more severe motor deficit was seen in a single transgenic F1 male of a
third independent founder (line 9832). This male died at an age of 5 weeks and the line was lost. Brain transgene mRNA levels in the line
9832 single F1 male (Fig. 1B, lane
4) superseded those detected in line 9813.
The progressive decline in motor performance was measured in a rotating
rod experiment. A group of transgenic (n = 7) versus nontransgenic (n = 12) littermate males of line 9813 were compared, starting at age 40 d and up to age 200 d (Fig.
2). The results show a progressive
decline in motor performance and a dramatic reduction in endurance of
the transgenic mice to remain on the rotating rod. A similar difference
and effect was observed when comparing aging (40-200 d) female
transgenic (n = 15) versus nontransgenic (n = 8; data not shown) mice of line 9813. The ANOVA
indicated a highly significant effect of genotype
(p < 0.001), as well as a significant age,
speed, and genotype interaction (p < 0.005; repeated measures ANOVA for two trial factors). A comparison of the performance curves of the two groups (transgenic and wild-type) revealed that, at both speeds 12 and 36 rpm, the performance of the
transgenic animals differed significantly (p < 0.001) from that of their nontransgenic littermates.

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Figure 2.
Rotating rod performance of transgenic mice.
Starting at age 40 d and up to age 200 d, transgenic
(n = 7) and C57BL/6 nontransgenic
(n = 12) littermate male mice were tested for
endurance to stay on the rotating rod. The mice were tested weekly, and
their performance is shown for two different rotation speeds, speed 1 (12 rpm) and speed 3 (36 rpm). C57BL/6 mice showed maximum endurance
performance (60 sec) at both speeds and as shown for speed 3 (36 rpm).
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The pronounced motor phenotype found in all of the mice of both A53T
transgenic lines and the documented expression of Thy1-based transgenes
in motor neurons (Aigner et al., 1995 ) prompted us to examine more
closely the pathological changes in these cells. In the anterior horns
of the spinal cord, ~80% of the motor neurons expressed the human
-synuclein A53T mutant protein, as shown by immunoreactivity for the
human -synuclein-specific antibody LB509 (Baba et al., 1998 ; Jakes
et al., 1999 ). Specific to the transgenic mice, many of these cells
showed diffuse perikaryal -synuclein staining (Fig.
3A) and some also showed
Lewy-like pathology (Fig. 3C, D) with pronounced
ubiquitin immunoreactivity (Fig. 3D). Furthermore, staining
with the Campbell-Switzer pyridine silver technique (Campbell et al.,
1987 ) (Fig. 3C), a routine and sensitive method used to
detect Lewy-type changes in human brain tissue (Braak and Braak, 1999 ;
Sandmann-Keil et al., 1999 ), revealed intense staining. These results
indicate that (rodent) motor neurons are susceptible to Lewy-like
changes when expressing the A53T mutant of human -synuclein. Other
changes associated with the development of the motor neuron pathology
(and seen also in other affected brain regions; data not shown)
included astrocytic gliosis (Fig. 3E) and microglial
activation (Fig. 3F).

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Figure 3.
Lewy-like pathology in the transgenic mouse spinal
cord. A-H correspond to sections through the anterior
horn. A, Prominent perikaryal and proximal neuritic
-synuclein staining of motor neurons in a transgenic mouse spinal
cord section but not in C57BL/6 (B).
C, Campbell-Switzer-stained motor neurons in a
transgenic mouse spinal cord, which also immunoreacted with
anti-ubiquitin antibody (D). E,
G, Anti-GFAP and anti-phosphotyrosine antibody stainings
(F, H) in transgenic
(E, F) versus nontransgenic
(G, H) C57BL/6 spinal cord show evidence for
astrocytic gliosis (E) and reactive microglia
(F) specific to the transgenic tissue. Scale
bars: A-D (in D), 20 µm;
E-H (in H), 20 µm.
Magnification: A-D, 250×; E-H,
200×.
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Spinal roots (Fig. 4A)
and nerve fiber bundles in muscles (Fig. 4C) immunostained
for -synuclein. Axonal degeneration was apparent in spinal roots,
with nerve fibers showing breakdown and segmentation into ellipsoids of
the myelin sheath (Fig. 4B). Also, skeletal muscles
contained small angular fibers (Fig. 4D, arrowheads), indicating neurogenic muscular atrophy,
consistent with the denervation and neuropathology observed to varying
degrees at NMJs of gastrocnemius muscle taken from several line 9813 mice (n = 7, age 6.5 months; Fig.
4E-J). Depending on the individual mouse,
10-40% of the synapses were denervated and thinning of preterminal
nerves, and/or swellings were detected in at least 50% of innervated
synapses. Pathological changes were also observed in two other muscles,
the EDL, containing fast-twitch muscle fibers, and the soleus, which
contains mostly slow-twitch muscle fibers (Fig.
5). Whereas the structure of the
postsynaptic apparatus, visualized by -bungarotoxin, was similar in
transgenic and wild-type mice, the presynaptic motor neurons showed
clear signs of degeneration. In transgenic but not in wild-type C57BL/6
littermates, NMJs often showed a reduction in the neurofilament
staining, indicating that motor neurons were about to retract from
synapses (Fig. 5C, D). Moreover, neurofilament
staining in more proximal regions of the motor nerve was discontinuous
(data not shown). The hypothesis that motor neurons abandon synaptic
sites was supported in staining for the synaptic vesicle protein
synaptophysin (Fig. 5A, B). In wild-type animals, synaptophysin matches the outline of the
postsynaptic acetylcholine receptors (AChRs) (Fig.
5A). In transgenic animals, synaptophysin appeared punctated
and thinner so that it did not cover the entire area of AChR aggregates
(Fig. 5B). The finding that neurodegeneration including
denervation of NMJs is observed in all of the muscles examined suggests
that a universal mechanism of synapse maintenance is affected by
transgene expression of human -synuclein. Together with the
neuropathological changes detected in central areas (see below),
including some that are involved in motor function (e.g., globus
pallidus; data not shown), these findings provide a likely explanation
for the observed reduction in complex motor performance.

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Figure 4.
Neuromuscular degeneration. A,
Longitudinal section of a spinal root with human
-synuclein-immunoreactive (LB509 antibody) nerve fibers that are
specific to the transgenic mice (C57BL/6 not shown).
B, Holmes-Luxol-stained spinal root showing axonal
degeneration with breakdown and segmentation of myelin into ellipsoids
("digestive chambers"). C, Cross-sectioned bundle of
nerve fibers in a muscle showing strongly human -synuclein-specific
(antibody LB509) immunoreactive axons. D,
Cross-sectioned muscle fiber bundle containing small angular fibers
consistent with denervation (arrowheads), indicating
neurogenic muscle atrophy (Holmes-Luxol stain). Scale bars:
A-D, 20 µm. E-J, Medial gastrocnemius
NMJs from C57BL/6 (E) and two different line 9813 mice (mouse 1, F-H; mouse 2, I,
J), aged 6.5 months. The combined silver-esterase
reaction reveals nerves in black and the synaptic
acetylcholine esterase reaction product (asterisks) in
blue. NMJs in the transgenic mice show
neuropathological changes ranging from swellings of preterminal nerves
(F, arrow), thinning out of the
preterminal nerve (G), retraction of the nerve
from the synaptic region (H), to complete
denervation (I, arrows). A thin and
characteristically twisted nerve sprout (arrows) has
regrown to a denervated synapse shown in J. Dark
ovals (in I and J) are
attributable to background labeling of nuclei. Scale bar, 40 µm. Magnification: A, 100×; B,
C, 400×; D, 200×; E-J,
400×.
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Figure 5.
Neurodegeneration of soleus neuromuscular
junctions. A-D, The structure of the
postsynaptic apparatus is visualized by -bungarotoxin staining of
AChRs (green), which was similar in C57BL/6
(A, C) and transgenic (B,
D) mice. Costainings are shown for -bungarotoxin
(green) and synaptophysin (A,
B), and -bungarotoxin and neurofilament
(C, D). Scale bar, 3 µm. Magnification,
700×.
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To investigate pathological changes in the brain more closely, animals
of both lines, aged 12 weeks and older (n = 19), were examined by applying immunohistochemical techniques routinely used to
assess Lewy pathology in human brain (Gai et al., 1995 ; Forno, 1996 ;
Spillantini et al., 1997 ; Wakabayashi et al., 1997 ; Baba et al., 1998 ;
Ince et al., 1998 ; Mezey et al., 1998 ; Takeda et al., 1998 ). In
transgenic mouse brains, many neurons in the telencephalon (Fig.
6A,B,D,E)
and brainstem (Fig.
7B,C)
showed intense -synuclein staining in cell bodies and dendrites.
This pattern was seen when using an antibody that specifically detects human but not mouse -synuclein (Fig.
6A,D; for negative control, see
Fig. 3B). It was also seen when using an antibody that
detects both mouse and human -synuclein (Figs.
6B,E,
7B,C) and in sharp contrast to the
axonal and presynaptic distribution of endogenous mouse
-synuclein in the nervous system of nontransgenic mice (Fig. 6
C, F).

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Figure 6.
-Synuclein protein expression in the transgenic
mouse brain. A-F, -Synuclein staining in the
hippocampal CA1 region (A, B) and
neocortex (D, E) of a transgenic mouse
compared with the respective regions in a nontransgenic C57BL/6 mouse
(C, F). Unlike in the transgenic
brain, the C57BL/6 hippocampus lacks -synuclein immunoreactivity in
CA1 pyramidal cell bodies in stratum pyramidale (st.p.).
In both mice, immunostaining is prominent in stratum radiatum
(st.r.). Strongly immunoreactive neurites (i.e., CA1
cell dendrites) in stratum radiatum are specific to the transgenic
brain. Similar dendritic structures in the C57BL/6 brain appear pale
and without -synuclein. Immunostaining was in paraffin
(A, D; human -synuclein-specific
antibody LB509) and free-floating brain sections (B,
C, E, F; antibody detects
both mouse and human -synuclein). Scale bars: A,
D (in D), 20 µm (250× magnification);
B, C, E, F (in F), 20 µm
(200× magnification).
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Figure 7.
-Synuclein and ubiquitin in transgenic mouse
and human PD brain. A-F, Sections are shown of a human
PD substantia nigra (A, D) and a
transgenic mouse brain pontine reticular nucleus (B,
C, E, F)
immunostained for -synuclein (A-C) and
ubiquitin (D-F). Note the prominent
somatodendritic staining for -synuclein and the neuritic staining
for ubiquitin in both human and mouse neurons. Lewy-like neurites are
indicated by arrowheads. A cell of the substantia nigra
in the human PD brain shows a Lewy body inclusion (A,
arrow). G, H, Two
consecutive 3 µm paraffin sections of the same group of cells in a
cerebellar nucleus, stained for -synuclein (LB509 antibody;
G) and ubiquitin (H).
G, Several neurons showing similar degrees of perikaryal
-synuclein immunoreactivity. Many cross-sectioned neurites are also
stained. H, Abundant ubiquitin immunoreactivity is seen
in only one of the three grouped cells and a nearby neurite
(arrowheads in H and G
indicate the same cell and neurite showing -synuclein
immunoreactivity). In addition, compared with the number of
-synuclein-positive neurites in G, in
H a smaller number of these structures (dark and
punctate) show immunoreactivity for ubiquitin. Scale bars:
A, D, 20 µm (magnification:
A, 320×; D, 630×); B, C,
E-H (in H), 20 µm
(magnification, 400×).
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Increased perikaryal and neuritic staining of neurons by -synuclein
antibodies is one characteristic feature in the diseased human brain
(Spillantini et al., 1997 ; Wakabayashi et al., 1997 ; Baba et al., 1998 ;
Irizarry et al., 1998 ; Mezey et al., 1998 ; Spillantini et al., 1998 ;
Braak et al., 1999 ). Compared with affected neurons in human PD brain
(Fig. 7A), -synuclein staining in transgenic mouse brains
showed heterogeneous changes in neurites, very similar to those
observed in human brain (Forno, 1996 ; Wakabayashi et al., 1997 ;
Spillantini et al., 1997 ; Baba et al., 1998 ; Ince et al., 1998 ;
Irizarry et al., 1998 ; Mezey et al., 1998 ; Spillantini et al., 1998 ;
Takeda et al., 1998 ; Braak et al., 1999 ). Frequently observed changes
included sausage-like enlargements of proximal and distal neuritic
segments, thick or fine thread-like inclusions, as well as beaded or
spindle-shaped neurites (Fig.
7B,C). They were most prominent and
frequent in areas including the nucleus centralis oralis pontis, the
nucleus vestibularis lateralis, the deep cerebellar nuclei, the deep
aspects of the tectal plate, and as shown above (Fig. 3), motor nuclei
in the spinal cord.
Immunostaining for ubiquitin is also frequently used to visualize Lewy
pathology in human brain (Gai et al., 1995 ; Forno, 1996 ; Spillantini et
al., 1997 ; Wakabayashi et al., 1997 ; Baba et al., 1998 ; Ince et al.,
1998 ; Irizarry et al., 1998 ; Mezey et al., 1998 ; Spillantini et al.,
1998 ; Takeda et al., 1998 ; Braak et al., 1999 ; Gómez-Tortosa et
al., 2000b ). In the transgenic mice, dystrophic neurites and cell
bodies occasionally stained intensely for ubiquitin (Fig.
7E,F). The stained neurites
displayed morphological features (Fig.
7E,F) similar to those seen
in human brains (Fig. 7D) with Lewy pathology (Gai et al.,
1995 ; Forno, 1996 ; Spillantini et al., 1997 ; Wakabayashi et al., 1997 ;
Baba et al., 1998 ; Ince et al., 1998 ; Irizarry et al., 1998 ; Mezey et
al., 1998 ; Spillantini et al., 1998 ; Takeda et al., 1998 ; Braak et al.,
1999 ). However, both neuronal cell bodies and neurites with ubiquitin
immunostaining were less frequent when compared with
-synuclein-positive cells and neurites (Fig.
7G,H) and were restricted primarily
to those regions that showed the most pronounced -synuclein
immunopathology in cells and neurites, including the nucleus centralis
oralis pontis, the nucleus vestibularis lateralis, the deep cerebellar
nuclei, the deep aspects of the tectal plate, and motor nuclei in the
spinal cord. Within each of these regions, neurons and neurites showed
no significant ubiquitin immunostaining, weak staining (with variable
degrees of punctate cytoplasmic and/or perinuclear immunolabeling), or
an intense ubiquitin immunostaining, as illustrated in two consecutive
3 µm paraffin sections (Fig. 7G,H).
These sections show the same set of cells and neuritic structures in a
cerebellar nucleus, stained for -synuclein (Fig. 7G) and
ubiquitin (Fig. 7H).
Ubiquitin compared with -synuclein immunopathology in human brains
with Lewy bodies and Lewy neurites is also less frequent (Forno, 1996 ;
Ince et al., 1998 ; Irizarry et al., 1998 ; Spillantini et al., 1998 ;
Takeda et al., 1998 ; Braak et al., 1999 ; Gómez-Tortosa et al.,
2000b ), suggesting that ubiquitination might be a late event in the
development of the pathology in mouse and human. Curiously,
ubiquitination was evident in some but not all of the mice with
-synuclein immunopathology, and the phenomenon was observed in both
lines (9813 and 9956) and sexes. For example, in one group of five
6-month-old transgenic mice of line 9813 that were processed
simultaneously for pathology, only two of the five animals showed a
prominent ubiquitin immunopathology in the restricted brain regions.
The stochastic manner in which ubiquitination appeared led us to
compare transgene mRNA levels between different mice and sexes within
each line but no differences between either individuals or sexes were
detected (data not shown). Apparently, factors other than these or
strain genetic background (all mice are C57BL/6) play a role in this phenomenon.
Finally, ultrastructural features of the human -synuclein-positive
neuronal inclusions were characterized by immunoelectron and
conventional electron microscopy. In contrast to nontransgenic C57BL/6
mice, which showed no staining with the LB509 human
-synuclein-specific antibody (data not shown; for reference, see
Fig. 3B), neurons of transgenic mice showed
-synuclein-containing granular deposits (Fig.
8A,B).
Using conventionally stained ultrathin sections, brainstem and spinal
cord tissue of transgenic but not nontransgenic mice showed dendrites
(often dilated) containing electron-dense finely structured granular
material (Fig. 8C). -Synuclein-immunoreactive fibrillar
components as seen in human brains with Lewy pathology (Spillantini et
al., 1997 ; Wakabayashi et al., 1997 ; Goedert et al., 1998 ; Takeda et
al., 1998 ) were not seen.

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Figure 8.
Ultrastructural features of neurons in
Thy1 SNA53T mice. Shown are immunoelectron (A,
B) and a conventional micrograph
(C) of spinal cord gray matter. A,
B, Five-month-old Thy1 SNA53T mouse of line 9813. The
immunoelectron micrographs are specifically stained for human but not
mouse -synuclein (LB509 antibody). A, Longitudinal
section through a small dendritic appendage showing prominent staining
of elements in the dendritic cytoplasm. B, Immunolabeled
cross-sectioned dendrite, showing the fine granular composition of the
-synuclein-containing structures, which occasionally appeared
attached to the endoplasmic reticulum and mitochondria, for example.
C, Conventionally stained electron micrograph of a
brainstem section of a 4-month-old transgenic mouse showing fine
granular electron-dense material in dendritic profiles, most evident in
the cross-sectioned dendrite located in the top right
part between the three larger and a smaller myelinated axon. Scale
bars: A, 1.7 µm (4500× magnification);
B, 0.6 µm (12,000× magnification); C,
1.9 µm (5000× magnification).
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The vast majority of human cases with Lewy pathology are idiopathic,
and -synuclein mutations in the coding region, other than A53T and
A30P, have not been found in cohorts of familial or sporadic PD (Chan
et al., 1998 ; Farrer et al., 1998 ; The French Parkinson's Disease
Study Group, 1998 ; Vaughan et al., 1998 ). To test whether the pathology
seen in the mice is unique for the A53T mutant of -synuclein, in
which case it could bear little on idiopathic forms of the diseases, we
also generated transgenic lines (n = 5) expressing
wild-type human -synuclein. Wild-type human -synuclein ( SNwt)
expression was under control of the mouse Thy1 regulatory sequences as
for the A53T mutant (Fig. 1A). Mice of one of these
lines (S969) showed a motor phenotype and expressed brain transgene
mRNA and protein levels similar to those in seen in Thy1 SNA53T mice
of line 9813 (data not shown). Brain and spinal cord contained many
neurons with pronounced -synuclein immunostaining in cell perikarya
and dendrites (Fig. 9). Cells and
neurites with Lewy-like features were prominent and frequent mainly in
those areas of the CNS as reported for the Thy1 SNA53T mice.
Two representative examples shown are from the deep mesencephalic nucleus (Fig. 9D) and the spinal cord (Fig.
9E,F). Gastrocnemius neuromuscular junctions showed in some regions over 50% denervation, and sprouting was often seen at the remaining endplates like in the
A53T mice (data not shown). In conclusion, like its A53T mutant, expression of wild-type human -synuclein can cause pathogenicity in
central neurons.

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Figure 9.
Immunopathology in Thy1 SNwt.
A, Cerebral cortex showing prominent somatic and
axodendritic -synuclein immunostaining on neurons of the deep
cortical layers. B, CA1 region of the hippocampus
showing prominent -synuclein immunostaining in principal cell somata
and dendrites. C, CA3 sector of the hippocampus. Note
some pyramidal cells with prominent cytoplasmic staining next to
unstained cells and the immunostaining of the mossy fiber terminals.
D, Deep mesencephalic nucleus with a neuron showing a
strong -synuclein immunostaining in soma and proximal
dendrites. Note the presence of unstained axons in the vicinity.
E, Spinal cord longitudinal section with
-synuclein-immunostained motor neurons and enlarged proximal
dendrites (arrow). F, Same area as in
E showing ubiquitin immunostaining in the cytoplasm of
some neurons. Scale bars: A, B (in
B), 20 µm; C, D (in
D), 20 µm; E, F (in
F), 20 µm. Magnification: A,
B, 100×; C, D, 250×;
E, F, 320×.
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 |
DISCUSSION |
The transgenic mice described here cover a remarkable spectrum of
the pathological changes that are seen in postmortem brain tissue of
DLB, PD, and LBVAD patients. Our results identify the A53T mutant of
human -synuclein and its wild-type counterpart as pathogenic agents
that can drive the formation of extranigral pathology in rodent central
neurons. The A53T mutation may enhance but is not required for
pathogenicity of the human protein. This finding is in
agreement with recent reports describing its pathogenicity in
transgenic mice (Masliah et al., 2000 ) and Drosophila
(Feany and Bender, 2000 ). Expression of the human -synuclein A30P
mutant has also revealed changes in neurons that are reminiscent of
Lewy-like pathology in both the mouse (Kahle et al., 2000a ,b ) and the
fly (Feany and Bender, 2000 ). Therefore, all three human -synuclein proteins can be pathogenic in neurons in vivo. In each
case, their expression resulted in aberrant perikaryal and dendritic
accumulations of -synuclein in neurons, suggesting that this could
play a central role in the development of the pathology. In our mice,
human -synuclein expression also induced motor neuron degeneration,
with profound effects on axonal integrity, and denervation of NMJs in
several muscles examined. These observations suggest that -synuclein (over)expression affects a (perhaps universal) mechanism of synapse maintenance. Whether the three human -synuclein proteins affect one
or different (for example, axonal transport; Jenssen et al., 1999 ) mechanisms and with similar or different thresholds for pathogenicity remains to be determined. However, because the
-synuclein gene is infrequently mutated in its coding sequence, it
will be key to identify and study cellular processes that facilitate
-synuclein protein accumulation, such as after insult (Kowall et
al., 2000 ; Vila et al., 2000 ), or its degradation, which likely
involves the proteasome-ubiquitin pathway (Leroy et al., 1998 ; Bennett et al., 1999 ).
An interesting feature of the pathology in our transgenic mice and in
human diseases with Lewy pathology (Braak et al., 1996 ; Forno, 1996 ;
Ince et al., 1998 ; Takeda et al., 1998 ; Braak et al., 2000 ) is a
selective and topographically confined vulnerability of neurons to
develop Lewy (human) or Lewy-like (mouse) pathology. In the mice,
prominently affected areas included the nucleus centralis oralis
pontis, the nucleus vestibularis lateralis, the deep cerebellar nuclei,
the deep aspects of the tectal plate, and motor nuclei in the spinal
cord. Of course, the pattern in the mouse is dictated a
priori by the properties of the Thy1 gene-based expression
cassette. This cassette yielded widespread neuronal expression of
-synuclein. However, pathology was most pronounced in certain brain
regions, suggesting that some neurons are more vulnerable. Perhaps
modulators of -synucleinopathy vary regionally in the brain. The
Thy1 cassette generally fails to express in dopaminergic neurons of the
substantia nigra pars compacta (S. Bischoff and H. van der Putten,
unpublished observations), and we confirmed this to be the case also in
the A53T transgenic mice (data not shown). In the human brain, the dopaminergic cells of the substantia nigra pars compacta appear most
sensitive to develop Lewy pathology, and the resulting nigral lesions
are primarily involved in the clinical symptoms of PD (Forno, 1996 ;
Spillantini et al., 1997 ; Wakabayashi et al., 1997 ; Baba et al., 1998 ;
Ince et al., 1998 ; Irizarry et al., 1998 ; Mezey et al., 1998 ;
Spillantini et al., 1998 ; Takeda et al., 1998 ; Braak et al., 1999 ).
Furthermore, when using transgene cassettes that allow for expression
in dopaminergic neurons, these cells seem highly prone to develop
Lewy-like pathology in both mouse (Masliah et al., 2000 ) and fly (Feany
and Bender, 2000 ). However, extranigral Lewy pathology is very common
in both PD and DLB brains (Gai et al., 1995 ; Braak et al., 1996 , 2000 ;
Forno, 1996 ; Gómez-Tortosa et al., 2000a ), and it is suspected to
contribute to the variable cognitive and neuropsychiatric features in
these diseases. By excluding transgene effects in dopaminergic neurons
of the substantia nigra pars compacta, Thy1 SN mice seem particularly
useful to address and model extranigral aspects of the pathology as it
is seen in PD and DLB.
The remarkable spectrum of pathological changes seen in the mice
included subsets of central neurons showing -synuclein-stained perikarya, dendrites, Lewy-like neurites, and a smaller subset of these
cells staining for ubiquitin. In contrast, no pathological staining was
observed when using antibodies that detect paired helical filament and
hyperphosphorylated tau, neurofilaments, or when using stains to detect
A plaque-like pathology (Sturchler-Pierrat et al., 1997 ; data not
shown). Ubiquitination was evident in some but not in all aged-matched
female and male mice, and this phenomenon was observed in both A53T
lines. Because all of the mice were C57BL/6 and no variation in
transgene expression was detected between individuals or sexes within a
line, factors other than these seem to account for ubiquitination
occurring in a stochastic manner.
Like in human PD and DLB brains (Forno, 1996 ; Ince et al., 1998 ;
Irizarry et al., 1998 ; Spillantini et al., 1998 ; Takeda et al., 1998 ;
Braak et al., 1999 ; Gómez-Tortosa et al., 2000b ), ubiquitination
in transgenic mouse neurons appears to be a late modification in cells
with -synuclein pathology. It was evident in only a subset of human
-synuclein-immunopositive mouse neurons and neurites (Fig.
7G, H) and found mainly in those brain
regions that showed the most pronounced -synuclein immunopathology.
A quantification of the number of perikarya and neurites showing ubiquitin versus -synuclein immunopathology was not attempted because, unlike in human brains with Lewy pathology, the pattern and
the intensity of ubiquitin immunolabeling was very heterogeneous. In
DLB, percentages of -synuclein-positive but ubiquitin-negative structures ranged only from 2 to 10% depending on brain region (Gómez-Tortosa et al., 2000b ). Morphologically, and compared with
classical Lewy bodies, these structures corresponded to less aggregated
and less compact -synuclein inclusions, such as pale bodies (Dale et
al., 1992 ). -Synuclein compared with ubiquitin antibodies thus
showed higher sensitivity for identifying less aggregated and less
compacted inclusions but little differences with respect to identifying
classical Lewy bodies. In the mice, we have not seen classical
Lewy body-like structures. Perikarya and neurites contained less
compact and more diffuse -synuclein-immunopositive material. A
significant proportion of -synuclein-immunopositive perikarya
and neurites failed to show or had different degrees of punctate
ubiquitin staining. Only occasional cells and neurites showed very
intense ubiquitin immunostaining (Fig. 7G,
H). Therefore, compared with human brains with Lewy
pathology, the majority of -synuclein-positive inclusions in the
mice may represent less compact -synuclein conglomerates associated
with pre-ubiquitination or early stages of ubiquitination. In
human brains, ubiquitinated structures represent mainly classical Lewy
bodies and Lewy neurites, and punctate ubiquitin immunopathology is
less frequent (Gómez-Tortosa et al., 2000b ). Perhaps aging and/or
species differences account for these observations and also for the
prominent, diffuse, ubiquitin staining seen in the cytoplasm of
occasional mouse but not human neuronal cell bodies (Fig.
6E,F) in which it is usually
confined to Lewy bodies (Gai et al., 1995 ; Forno, 1996 ; Ince et al.,
1998 ; Irizarry et al., 1998 ; Spillantini et al., 1998 ; Takeda et al., 1998 ; Braak et al., 1999 ; Gómez-Tortosa et al., 2000b ).
Morphologically, ubiquitin staining of dystrophic neurites is
remarkably similar in both species (Fig. 7D-F,
H).
Using transmission and immunoelectron microscopy, human -synuclein
A53T-immunoreactive granular material was detected in cytoplasm,
dendrites, and occasionally in axons of A53T mice. Granular material
with -synuclein has been seen in human tissue with Lewy pathology
and in partially purified human Lewy bodies (Arima et al., 1998 ; Baba
et al., 1998 ; Goedert et al., 1998 ; Wakabayashi et al., 1998 ). We did
not detect the typical -synuclein decorated Lewy body filaments as
seen in material extracted from human DLB cingulate cortex (Spillantini
et al., 1998 ), in tissue sections from human PD and DLB brain (Arima et
al., 1998 ; Baba et al., 1998 ; Wakabayashi et al., 1998 ), and in
synthetic -synuclein filaments (Conway et al., 1998 ; Crowther et
al., 1998 ; El-Agnaf et al., 1998 ; Giasson et al., 1999 ; Narhi et al.,
1999 ; Wood et al., 1999 ). This could relate to insufficient aging of
the mice and/or species differences. Others recently reported granular but no fibrillar material in mice expressing wild-type human
-synuclein (Masliah et al., 2000 ), whereas in Drosophila
fibrillar material was seen (Feany and Bender, 2000 ). These different
findings are intriguing because the identity of the pathogenic species
in diseases with Lewy pathology and its relationship to the
-synuclein-containing fibril has not been elucidated, and it is not
known whether Lewy bodies in human diseases are cytotoxic, harmless
side products, or markers of cell damage. Irrespective, and
likely more important, are the several other striking similarities seen
between the pathology in human and the transgenic mice. All three
(wild-type, A30P, and A53T) -synuclein proteins produce
nonfibrillar oligomers (Conway et al., 2000 ) that perhaps are
critical in pathogenesis, whereas fibrils and/or Lewy bodies could
represent harmless epiphenomena.
In conclusion, the changes in the transgenic mice correlate with
neurodegeneration, confirming that such mouse models provide a useful
means to address fundamental aspects of disorders with -synucleinopathy and novel animal models for testing therapeutic strategies.
 |
FOOTNOTES |
Received April 5, 2000; revised May 22, 2000; accepted May 25, 2000.
We thank Hanny Richener, Claudia Falk, Dr. Edgar Kaeslin, Corina
Schneider and Areejittra Soontornmalai, Rita Meyerhofer, and Dr.
Reinhard Bergmann for assistance with cloning, DNA microinjections, histology, behavioral analysis, and statistical advice, respectively.
Correspondence should be addressed to Herman van der Putten at the
above address. E-mail: p_herman.van_der_putten{at}pharma.novartis.com.
 |
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10813 - 10818.
[Abstract]
[Full Text]
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M. K. Lee, W. Stirling, Y. Xu, X. Xu, D. Qui, A. S. Mandir, T. M. Dawson, N. G. Copeland, N. A. Jenkins, and D. L. Price
Human alpha -synuclein-harboring familial Parkinson's disease-linked Ala-53 right-arrow Thr mutation causes neurodegenerative disease with alpha -synuclein aggregation in transgenic mice
PNAS,
June 25, 2002;
99(13):
8968 - 8973.
[Abstract]
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N. Golts, H. Snyder, M. Frasier, C. Theisler, P. Choi, and B. Wolozin
Magnesium Inhibits Spontaneous and Iron-induced Aggregation of alpha -Synuclein
J. Biol. Chem.,
May 3, 2002;
277(18):
16116 - 16123.
[Abstract]
[Full Text]
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R. G. Perez, J. C. Waymire, E. Lin, J. J. Liu, F. Guo, and M. J. Zigmond
A Role for alpha -Synuclein in the Regulation of Dopamine Biosynthesis
J. Neurosci.,
April 15, 2002;
22(8):
3090 - 3099.
[Abstract]
[Full Text]
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D. Kirik, C. Rosenblad, C. Burger, C. Lundberg, T. E. Johansen, N. Muzyczka, R. J. Mandel, and A. Bjorklund
Parkinson-Like Neurodegeneration Induced by Targeted Overexpression of alpha -Synuclein in the Nigrostriatal System
J. Neurosci.,
April 1, 2002;
22(7):
2780 - 2791.
[Abstract]
[Full Text]
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H.-J. Lee, C. Choi, and S.-J. Lee
Membrane-bound alpha -Synuclein Has a High Aggregation Propensity and the Ability to Seed the Aggregation of the Cytosolic Form
J. Biol. Chem.,
January 4, 2002;
277(1):
671 - 678.
[Abstract]
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P. J. Kahle, M. Neumann, L. Ozmen, V. Muller, S. Odoy, N. Okamoto, H. Jacobsen, T. Iwatsubo, J. Q. Trojanowski, H. Takahashi, et al.
Selective Insolubility of {alpha}-Synuclein in Human Lewy Body Diseases Is Recapitulated in a Transgenic Mouse Model
Am. J. Pathol.,
December 1, 2001;
159(6):
2215 - 2225.
[Abstract]
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M. Meins, P. Piosik, N. Schaeren-Wiemers, S. Franzoni, E. Troncoso, J. Z. Kiss, C. Brosamle, M. E. Schwab, Z. Molnar, and D. Monard
Progressive Neuronal and Motor Dysfunction in Mice Overexpressing the Serine Protease Inhibitor Protease Nexin-1 in Postmitotic Neurons
J. Neurosci.,
November 15, 2001;
21(22):
8830 - 8841.
[Abstract]
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E. Paxinou, Q. Chen, M. Weisse, B. I. Giasson, E. H. Norris, S. M. Rueter, J. Q. Trojanowski, V. M.-Y. Lee, and H. Ischiropoulos
Induction of {alpha}-Synuclein Aggregation by Intracellular Nitrative Insult
J. Neurosci.,
October 15, 2001;
21(20):
8053 - 8061.
[Abstract]
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Y. Tanaka, S. Engelender, S. Igarashi, R. K. Rao, T. Wanner, R. E. Tanzi, A. Sawa, V. L. Dawson, T. M. Dawson, and C. A. Ross
Inducible expression of mutant {{alpha}}-synuclein decreases proteasome activity and increases sensitivity to mitochondria-dependent apoptosis
Hum. Mol. Genet.,
April 1, 2001;
10(9):
919 - 926.
[Abstract]
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M. S. Nielsen, H. Vorum, E. Lindersson, and P. H. Jensen
Ca2+ Binding to alpha -Synuclein Regulates Ligand Binding and Oligomerization
J. Biol. Chem.,
June 15, 2001;
276(25):
22680 - 22684.
[Abstract]
[Full Text]
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