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The Journal of Neuroscience, May 15, 1998, 18(10):3757-3766
Removal of Polysialic Acid-Neural Cell Adhesion Molecule Induces
Aberrant Mossy Fiber Innervation and Ectopic Synaptogenesis in the
Hippocampus
Tatsunori
Seki1 and
Urs
Rutishauser2
Departments of 1 Neurosciences and
2 Genetics, Case Western Reserve University, Cleveland,
Ohio 44106
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ABSTRACT |
The mossy fiber axons of both the developing and adult dentate
gyrus express the highly polysialylated form of neural cell adhesion
molecule (NCAM) as they innervate the proximal apical dendrites of
pyramidal cells in the CA3 region of the hippocampus. The present study
used polysialic acid (PSA)-deficient and NCAM mutant mice to evaluate
the role of PSA in mossy fiber development. The results indicate that
removal of PSA by either specific enzymatic degradation or mutation of
the NCAM-180 isoform that carries PSA in the brain causes an aberrant
and persistent innervation of the pyramidal cell layer by mossy fibers,
including excessive collateral sprouting and/or defasciculation of
these processes, as well as formation of ectopic mossy fiber synaptic
boutons. These results are considered in terms of two possible effects of PSA removal: an increase in the number of mossy fibers that can grow
into the pyramidal cell layer and an inhibition of process retraction
by formation of stable junctions including synapses. As these defects
on granule cells in the adult animal and PSA-positive granule cells
continue to be produced in the mature brain, the present findings may
be relevant to previous studies suggesting that PSA-NCAM function
is required for long-term potentiation, long-term depression, and
learning behaviors associated with hippocampus.
Key words:
hippocampal development; polysialic acid; neural cell
adhesion molecule; mossy fiber innervation; mossy fiber synaptogenesis; dentate gyrus
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INTRODUCTION |
The polysialic acid (PSA) moiety of
neural cell adhesion molecule (NCAM) can serve as a negative regulator
of cell interactions and is known to be associated with a variety of
developmental processes that require plasticity in these interactions,
including cell migration and the guidance and targeting of axons (for
review, see Rutishauser and Landmesser, 1996 ). Moreover, PSA expression persists in certain regions of the adult brain known to exhibit physiological plasticity or self-renewal, including the olfactory bulb,
suprachiasmatic nucleus, hippocampus, hypothalamus, and certain nuclei
of the spinal cord (Theodosis et al., 1991; Bofanti et al., 1992; Seki
and Arai, 1993a). In the hippocampus, PSA expression by newly generated
granule cells and their axons occurs both during development and in the
adult (Seki and Arai, 1993b, 1995). In addition to these expression
patterns, the loss of PSA-NCAM in NCAM-deficient mice or wild-type
mice treated with the PSA-specific endoneuraminidase (endo N) has been
associated with alterations in a variety of brain functions, including
learning and memory behaviors (Cremer et al., 1994; Becker et al.,
1996), maintenance of circadian rhythmicity (Shen et al., 1977), and
both long-term potentiation and long-term depression in the hippocampus
(Muller et al., 1996).
Although these expression patterns and correlations with higher-order
tissue functions suggest that PSA-NCAM plays a significant role in
brain physiology, there has been little study of the possible cellular
mechanisms by which these effects are obtained. With the developmental
processes of axon innervation and neural precursor migration, the
details of altered cell position and morphology, as well as the nature
of the interactions being affected by PSA, have been investigated
(Landmesser et al., 1990; Ono et al., 1994; Tang et al., 1994; Daston
et al., 1996). In contrast, the characterization of the architectural
basis for the adult CNS defects has been limited to a brief description
of a delamination of the pyramidal cell layer in the hippocampus of
NCAM mutant mice (Tomasiewics et al., 1994).
Two more detailed studies of hippocampal structure in PSA-deficient
mice have been undertaken: a recent analysis of the mossy fiber layer
by conventional Timm's and Golgi's stainings in adult NCAM-null
mutants (Cremer et al., 1997), and the present study using DiI tracing
and synapsin I labeling of mossy fibers together with an enzymatic and
mutational perturbation of PSA-NCAM. In our approach, we have been
able to obtain a high-resolution description of the mossy fiber
projection and, in particular, of thin fibers and synaptic terminals
located in the pyramidal cell layer. Moreover, by comparing the
enzymatic and mutational models, it has been possible to evaluate the
specific role of PSA and the effects of genetic background differences
that reside in the mutant population.
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MATERIALS AND METHODS |
Animals and reagents. CF1 and 129/SvJ mice were
obtained from Charles River Laboratories (Wilmington, MA) and Jackson
ImmunoResearch (West Grove, PA), respectively. The NCAM-180-deficient
mice were generated as described by Tomasiewics et al. (1994).
Forty-three CF1, nine 129/Sv, and seven NCAM-180-deficient mice were
used for analyzing mossy fiber distribution. Endo N was prepared by the
method of Hallenbeck et al. (1987). Both the anti-PSA antibodies and
endo N have been shown to have a strict specificity for PSA and do not
recognize or affect any other sialic acid-containing structures in the
embryo (Hallenbeck et al., 1987; Sato et al., 1995). The mouse
monoclonal antibody (mAb) 12E3 (IgM) against PSA was prepared as
described by Seki and Arai (1991a). Mouse IgG monoclonal anti-synapsin
I was obtained from Calbiochem (San Diego, CA). Peroxidase-conjugated
goat anti-mouse IgM, peroxidase-conjugated goat anti-mouse IgG,
fluorescein-conjugated goat anti-mouse IgM, and rhodamine-conjugated
goat anti-mouse IgG were purchased from Cappel (West Chester, PA).
Endo N injection. To remove PSA from the brain with endo N,
1 µl of the enzyme (at a dilution of over 1:2000) was injected into
the lateral ventricle of postnatal day 1 (P1) CF1 mice with a glass
micropipette, as described previously (Ono et al., 1994). The endo N
diffused rapidly throughout the brain and removed all detectable PSA
within 1 d for 3-4 weeks. For control mice, the same amount of
boiled endo N was injected in the same manner as with nonboiled endo N
mice. The mossy fiber distribution was analyzed 15 d and 1.5 months after the injection. Each experimental group consisted of 9-12
animals.
Immunohistochemistry. Animals were deeply anesthetized with
sodium pentobarbital and perfused intracardially first with PBS followed by 4% paraformaldehyde in 0.1 M phosphate buffer
(PB), pH 7.4, for light microscopic studies, or by 4% paraformaldehyde and 0.1% glutaraldehyde in PB for electron microscopic studies. The
brains were removed from the skull and post-fixed overnight in 4%
paraformaldehyde in PB at 4°C. The cerebral cortices containing the
hippocampal formation were dissected away from the remaining brain
structure, and 1- to 2-mm-thick slices were cut in a plane transverse
to the septotemporal axis of the hippocampal formation at the
approximate midpoint of the axis. For cryostat sections, the slices
were kept in 20% sucrose in PBS at 4°C overnight, embedded in OTC
compound, and then cut by a cryostat into 10 µm sections. For light
microscopy of vibratome sections and electron microscopy, the slices
were cut by a vibratome into 50 µm thickness.
Cryostat or vibratome sections were washed with PBS and pretreated with
100% methanol containing 0.3% H2O2 for 30 min, followed by washing with PBS. The sections were first reacted with
mouse IgM mAb 12E3 (1:5000) or mouse monoclonal IgG anti-synapsin I (1:50) at 4°C for 24 or 48 hr, and after washing with PBS the sections were incubated at room temperature for 1-2 hr with goat anti-mouse IgM conjugated with peroxidase (1:100) or goat anti-rabbit IgG conjugated with peroxidase (1:100). Next, the sections were washed
with PBS and incubated in 0.02% 3,3'-diaminobenzidine
tetrahydrochloride (DAB) and 0.005% H2O2 in
0.05 M Tris buffer, pH 7.6, for 5-10 min. In vibratome
sections, the sections were preincubated with DAB for 30 min, and then
0.005% H2O2 was added. The sections were counterstained with methyl green.
Immunoelectron microscopy. The vibratome sections were
incubated in 0.1 M NaIO4 (10 min) and then in
NaBH4 (15 min), followed by immersion in 5%
dimethylsulfoxide (30 min) at room temperature. Next, the sections were
incubated with mouse IgM mAb 12E3 (1:5000) for 24-48 hr at 4°C and
then with anti-mouse IgM conjugated with peroxidase (1:100) for 3 hr at
room temperature. The sections were incubated with DAB solution for 30 min and then incubated with a DAB solution containing 0.005%
H202 for 5-10 min. Each of the above steps was
followed by washing with PBS. Finally, the sections were post-fixed
with 1% OsO4 in PB, dehydrated, and embedded in Epon 812. Ultra-thin sections were mounted on uncoated grids, stained with lead
citrate, and examined using a JOEL 1200CX microscope.
DiI labeling and photoconversion. Mice were perfused with
4% paraformaldehyde in PB under deep sodium pentobarbital anesthesia and immersed for 2-6 hr in the same fixative at 4°C. The cerebral cortices containing the hippocampal formation were dissected away from
the remaining brain structure. Then, ~1-mm-thick slices were cut in a
plane transverse to the septotemporal axis of the hippocampal formation
at the approximate midpoint of the axis, and the block of the medial
part of the dentate gyrus containing crescent was cut away. A 1% DiI
solution (Molecular Probes, Junction City, OR) in dimethylformamide was
then placed on the cut surface of the dentate gyrus (the hilus region).
Specimens were stored in the same fixative at 37°C for 1 week. For
photoconversion, the DiI-labeled vibratome sections were put in DAB
solution, and the specimens were illuminated for 1-2 hr with a Nikon
microscope using a 10× objective, an HBO mercury lamp, and a rhodamine
excitation filter (Bartheld et al., 1990). The DAB solution was
replaced every 30 min. The sections were mounted on slide glass and
counterstained with methyl green.
Quantitative analyses. Synapsin I-positive boutons in the
CA3a were counted in every second section, and an average of eight sections per mouse were analyzed. Each group consisted of 9-12 mice.
The statistical significance of the results was assessed by using
Student's t test. Although the terms CA3a-c are primarily based on the terminology of Ishizuka et al. (1990), for convenience in
quantitation of synapses we defined these subdivisions as follows. First, a straight horizontal line was drawn along the lower margin of
the pyramidal cell layer that corresponds to the infrapyramidal mossy
fiber band. Second, the proximal edge of the horizontal line was
determined by a vertical line that makes contact with the proximal edge
of the CA3 pyramidal cell layer, and the distal edge was determined by
a vertical line that makes contact with the outer margin of the
pyramidal cell curve. Third, two vertical lines were made to divide the
horizontal line (between the proximal and distal edges) into three
equal parts and in this study are referred to as CA3c, CA3b, and CA3a,
respectively.
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RESULTS |
PSA expression in the CA3 pyramidal cell layer
In previous studies, PSA-NCAM expression was found throughout the
entire dentate gyrus of early postnatal rats, followed by a persistence
of expression in the mossy fiber layer and a decrease in staining in
other regions (Seki and Arai, 1991b). As shown in Figure
1A, strong PSA
expression is seen in the large suprapyramidal and infrapyramidal mossy
fiber bundles, as well as in intrapyramidal mossy fibers that leave the
infrapyramidal mossy fiber bundle and run across the pyramidal cell
layer to join the suprapyramidal mossy fiber bundle. In addition to
these thick fiber bundles, PSA-positive mossy fibers penetrate into the
CA3 pyramidal cell layer and often display a dotted pattern of PSA
expression. Immunoelectron microscopic observation revealed many
PSA-positive fine fibers among pyramidal cells (Fig.
1B), whereas the pyramidal cells and typical mature
mossy fiber synaptic boutons were devoid of PSA (Fig. 1C).
The PSA-positive fibers contained many vesicles and at various points
made synapse-like junctions with pyramidal cell bodies. These junction
sites were also PSA-negative (Fig. 1B).
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Figure 1.
PSA expression in the hippocampal formation of a
15-d-old CF1 mouse. A, Strong PSA expression is seen in
the large suprapyramidal (SPMF) and
infrapyramidal (IPMF) mossy fiber bundles, as
well as in intrapyramidal mossy fibers that leave IPMF, run across the
pyramidal cell layer, and join the SPMF (small arrows).
In addition to these thick fiber bundles, fine PSA-positive fibers are
found in the pyramidal cell layer (large arrow). At high
magnification (inset) these small fibers often displayed
a dotted pattern of PSA expression (arrow).
GC, Granule cell layer; H, hilus. Scale
bar, 100 µm; inset, 25 µm. B,
Immunoelectron micrograph of PSA on a vesicle containing mossy fiber in
the CA3a pyramidal cell layer. The dotted staining pattern in the
inset of A is apparent as a patchy
distribution of PSA staining in which cell adherence junctions
(arrows) with pyramidal cell (PC) bodies
are located in the PSA-negative regions. Scale bar, 1 µm.
C, Immunoelectron micrograph showing a typical mature
mossy fiber terminal (T) with many
vesicles and several synapse-like junctions (arrows).
Unlike the neighboring darkly immunostained axonal process, this
terminal is PSA-negative. Scale bar, 1 µm.
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Development of mossy fibers in normal and endo N-treated mice
In the normal mouse and rat, innervation of the pyramidal cell
layer by mossy fibers begins in the early postnatal period and reaches
its mature configuration at P12-P15. Initially only suprapyramidal
mossy fibers are observed, but by P6-P9 as the bundle of the
suprapyramidal mossy fibers becomes thicker, large infrapyramidal mossy
fiber bundles are formed, and a few fine collateral sprouts penetrate
into the pyramidal cell layer (Amaral, 1979; Amaral and Dent, 1981;
Gaarskjaer, 1985) (our unpublished observations).
To evaluate the role of PSA in this process, endo N was injected into
the lateral ventricle of P1 mice, resulting in rapid diffusion of the
enzyme throughout the brain, and the mossy fibers and terminal boutons
were examined in P15 and 1.5-month-old mice. This study was greatly
aided by use of a combination of DiI labeling and photoconversion
techniques that enabled visualization of mossy fibers and their
terminal boutons. To establish the efficacy of endo N over this period,
PSA immunoreactivity was monitored at P15, 1 month, and 1.5 months
after the injection. No PSA was detected at P15, there was weak
staining on some granule cells and mossy fibers by P30, and by 1.5 months nearly normal levels of PSA expression had returned.
In mice treated with endo N, we did not observe a change in the overall
pattern or extent of the suprapyramidal bundle (Fig. 2A,B).
The most obvious effect of PSA removal concerned the thin processes in
the CA3 pyramidal cell layer region (Fig. 1A), and an
analysis of this perturbation was performed at P15 (Fig. 2).
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Figure 2.
Mossy fiber distribution in 15-d-old control
(A, C, E,
G) and endo N-injected (B,
D, F, H) CF1 mice.
The mossy fibers were labeled with DiI with photoconversion to a DAB
reaction product (see Materials and Methods). A, B,
Low-magnification micrograph showing that the large suprapyramidal
mossy fiber bundles are similar images in control
(A) and endo N-treated mice
(B). C, D,
Higher-magnification image of the CA3c subfield. In control mice
(C), the intrapyramidal (small
arrow) and infrapyramidal (large arrow) mossy
fibers are compactly bundled. In endo N-treated mice
(D), these bundles are more loosely arranged.
E, F, Higher-magnification image of the
CA3b subfield. In control mice (E), the
infrapyramidal mossy fibers (Figure legend continues)
(arrow) run as a fascicle below the
pyramidal cell layer. In endo N-treated mice
(F), the infrapyramidal mossy fibers are
unfasciculated and wander through the pyramidal cell layer, often
forming synapse-like structures on the pyramidal cells
(arrows). G, H,
Higher-magnification image of the CA3a subfield. In control mice
(G), fibers arising from the suprapyramidal mossy
fibers penetrate into the pyramidal cell layer and display small
varicosities. In endo N-treated mice (H),
such fibers are more numerous and possess a number of clearly defined
synaptic terminals. Scale bars: A, B, 100 µm; C-H, 25 µm.
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In control mice, the suprapyramidal and infrapyramidal mossy fibers
were formed as large compact bundles (Fig.
2A,C,E). The suprapyramidal bundles were observed above the CA3 pyramidal cells (stratum lucidum) and gave rise to a few individual processes penetrating the middle (CA3b) and distal (CA3a) parts of the pyramidal cell layer (Fig. 2E,G). Only a few
of these fine fibers contained mossy fiber boutons. The infrapyramidal
mossy fibers ran below the pyramidal cell layer and then usually curved
dorsally at the point of the proximal and middle CA3 pyramidal cell
layer to join the suprapyramidal mossy fibers (Fig.
2A,C).
In endo N-treated mice, the suprapyramidal mossy fiber bundles were
similar in appearance to those of control mice. However, there were
many more fine processes emanating from this bundle and penetrating
along erratic paths into the middle and distal CA3 pyramidal cell layer
(Fig. 2F,H). Some of these
processes possessed a number of typical mossy fiber boutons. Similarly, infrapyramidal mossy fibers were formed below the CA3 pyramidal cell
layer, but the bundle was less compact, with many fine fibers following
separate paths through the CA3 pyramidal cell layer (Fig.
2D). This behavior was clearest in the middle part of
the CA3 pyramidal cell layer in which the fibers continued to wander within the pyramidal cell layer and displayed numerous mossy fiber boutons (Fig. 2F). The morphological difference
between the infrapyramidal mossy fibers of control and endo N-treated
mice was also clear in electron micrographs (Fig.
3). In control mice, the unmyelinated mossy fiber axons were tightly fasciculated into large bundles. In
contrast, in endo N-treated animals the fascicles were much smaller and
disorganized, with many other elements such as basal dendrites and
terminal boutons penetrating into the bundles.
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Figure 3.
Electron micrograph of infrapyramidal mossy fibers
in the CA3c subfield of 15-d-old control (A) and
endo N-injected (B) CF1 mice. Sections were cut
perpendicular to the mossy fibers. In control mice, unmyelinated mossy
fiber axons were tightly fasciculated in large bundles
(asterisks), whereas in endo N-treated mice, the
fascicles were much smaller and disorganized, with many other elements
such as basal dendrites and terminal boutons penetrating into the
bundles. Scale bar, 2 µm.
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Mossy fiber synaptic boutons
Because mossy fiber boutons were a consistent feature of the
aberrant fibers in the endo N-treated mice, synapsin I
immunohistochemistry was used to identify mossy fiber terminals more
directly. In normal P15 animals, the synapsin I-positive mossy fiber
terminals were visualized as dark spots in a compact band corresponding
to the location of the large suprapyramidal and infrapyramidal mossy fiber bundles (Fig.
4A,C).
Few boutons were detected within the pyramidal cell layer in the CA3b
and CA3a subfields. In endo N-treated mice, the density of synapsin
I-positive boutons in the suprapyramidal mossy fiber bundles was not
significantly changed, although numerous boutons were found scattered
within the pyramidal cell layer in CA3c and CA3b (Fig.
4B,D). These results could be
readily quantitated, and at P15 the number of synapsin I-positive
terminals was approximately seven times greater in the CA3a pyramidal
layer of the PSA-negative mice than in control mice (Fig.
4E).
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Figure 4.
Mossy fiber terminal bouton distribution in the
subfields CA3b (A, B) and CA3a
(C, D) of 15-d-old control
(A, C) and endo N-injected
(B, D) CF1 mice as revealed by synapsin I
immunohistochemistry. A quantitation of mossy fiber bouton density in
the subfield CA3a of control and endo N-injected mice is shown in
E. In control animals, a large number of mossy fiber
boutons are seen in the suprapyramidal and infrapyramidal mossy fiber
band, and only a few are distributed within the pyramidal cell layer.
Significant differences were observed between control and endo
N-treated mice at both P15 and 1.5 months. In endo N-treated mice, a
larger number of boutons are seen scattered within the pyramidal cell
layer. Error bars indicate SD; p < 0.0001. Scale
bar, 25 µm.
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Mossy fiber patterns in young adult mice
An important aspect of the effects of endo N-induced removal of
PSA is that they persist in the adult hippocampus. As
noted above, by 1.5 months after the enzyme treatment at P1, PSA
resumed its normal level and pattern of expression. Nevertheless, the invasion of the infrapyramidal layer with fine mossy fibers persists with irregularly oriented intrapyramidal fine mossy fibers forming a
web between the suprapyramidal and infrapyramidal mossy fiber bundles
(Fig. 5). These aberrant fibers could
well have physiological consequences, because the number of synapsin
I-positive terminals in this region remains five times greater than in
controls (Fig. 4E).
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Figure 5.
Mossy fiber distribution in the CA3b subfield of
1.5-month-old control and endo N-injected (B) CF1
mice. The mossy fibers were labeled with DiI with photoconversion to a
DAB reaction product. In controls (A), the
suprapyramidal, infrapyramidal, and intrapyramidal mossy fibers are
compactly bundled. In endo N-treated animals (B),
the ectopic fibers seen at P15 persists with randomly oriented fine
mossy fibers distributed within the pyramidal cell layer and bearing
typical mossy fiber terminals. Scale bar, 25 µm.
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Development of mossy fibers in NCAM-180-deficient mice
As noted in previous studies on cell migration (Ono et al., 1994),
it is valuable to compare results obtained with endo N with those
produced by mutation of the NCAM gene. The advantage of endo N is that
it can be introduced at a particular stage (P1 in this study) and in
principle only affects PSA, whereas with mutation (in this study, the
creation of a mouse that does not produce the 180 kDa isoform of NCAM
that at these developmental stages carries nearly all of CNS-associated
PSA) it is effective throughout life and does not risk injection
artifacts or possible contaminants.
Before analyzing mossy fiber distribution in the NCAM-180-deficient
mice, it was established that in neonatal brain only very low levels of
PSA (possibly associated with other NCAM isoforms) were found on the
mutant mossy fibers. Another important consideration is the genetic
backgrounds of the controls and mutants. In the present experiments,
mossy fiber distributions were compared among wild-type CF1, wild-type
129/SvJ, and the NCAM-180-deficient mutation on a background containing
genes from both the CF1 and 129 strains. This combination presents a
potential problem, because different mouse strains can have
significantly different patterns of mossy fiber innervation (Barber et
al., 1974; Schwegler and Lipp, 1983), and in particular the 129 strain
has a large bifurcation of the mossy fiber bundles in CA3c and
sometimes CA3b that is not present in CF1 (Fig.
6, compare
A,C,E for 129; Fig. 2,
compare A,C,E for CF1)
or C57BL (Schwegler and Lipp, 1983). However, it may be noted that
Cremer et al. (1997) did not detect a difference in mossy fiber
distribution for 129 and C57BL mice as viewed by Timm's staining.
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Figure 6.
Mossy fiber distribution in 1-month-old
129/SvJ wild-type (A, C,
E, G) and NCAM-180-deficient
(B, D, F,
H) mice. The mossy fibers were labeled with DiI
and the fluorescence photoconverted to a DAB reaction product.
A, B, Low-magnification micrograph
showing that large mossy fiber bundles invade the CA3c pyramidal cell
layer in both 129 wild-type and NCAM-mutant mice. However, only in the
mutant do these fibers extend into the CA3a subfield (double
arrow). C, D,
Higher-magnification image of the CA3c subfield. In the mutant, a
larger number of fine mossy fibers arise from the intrapyramidal
bundle. These ectopic fibers are distributed randomly throughout the
lower part of the pyramidal cell layer and make mossy fiber synaptic
(Figure legend continues) terminals (arrows). E,
F, Higher-magnification image of the CA3b subfield. In
wild-type mice (E), intrapyramidal mossy fiber
bundles merge with supra- and infrapyramidal mossy fibers. In mutant
mice (F), the intrapyramidal mossy fibers track
into the pyramidal cell layer with many fine fibers randomly
distributed between the supra- and intrapyramidal mossy fibers and the
formation of numerous terminal structures. G,
H, Higher-magnification image of the CA3a subfield. In
the mutant mice (H), a disorganized group
of intrapyramidal mossy fibers penetrates into the pyramidal cell
layer. Scale bars: A, B, 100 µm;
C-H, 25 µm.
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Nevertheless, these strain differences between 129 and CF1 mice never
included the type of defasciculated and ectopic fibers seen in the
distal half (CA3a region) of the pyramidal cell layer of the endo
N-treated mice. In fact, the mutant mice used in this study have an
overall bundle pattern most similar to that of the wild-type 129 strain, with a splitting of the mossy fiber layer in CA3c and CA3b
(Fig.
6A,C,E,G),
plus a large number of defasciculated intrapyramidal mossy fiber in
CA3a. That is, in the mutant many fine mossy fibers were found to run
between suprapyramidal and intrapyramidal mossy fiber bundles, forming
a web between them, and many of these fibers displayed large
varicosities characteristic of mossy fiber boutons (Fig.
6D,F,H). Despite
this similarity between the enzyme and mutation-induced perturbations,
it should be noted that the mutant phenotype appears to be more extreme because there is a continued growth of defasciculated intrapyramidal fibers into CA3a (Fig.
6B,H). However, as with the
endo N treatment, we did not observe a change in the NCAM-mutant mice
in the overall pattern or extent of the suprapyramidal bundle (Fig.
6A,B).
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DISCUSSION |
The major finding of this study is that both the genetic deletion
of PSA-NCAM and the enzymatic removal of PSA at P1 from growing mossy
fibers in the hippocampus result in a partial misrouting of these axons
into the pyramidal cell layer. Associated with this change in pattern
is a defasciculation of mossy fiber bundles, wandering of these small
fibers along haphazard paths, and the frequent appearance of mossy
fiber terminals. These fibers and terminals persist in the mature
brain, even after the reappearance of PSA in the enzyme-treated
animals.
This discussion will begin with a comparison of the present study with
the recent report by Cremer et al. (1997). The focus of the earlier
study, which primarily used relatively low-resolution methods such as
Timm's, neurofilament, or tau staining, was on the extent of outgrowth
and reduction in bundle size of mossy fiber axons as detected in the
adult. Our analysis of the developing hippocampus used the
high-resolution DiI tracing methods and the specificity of synapsin I
staining to examine the behavior of both thick and fine fibers, as well
as synaptic terminals, in the mossy fiber and pyramidal cell
layers.
The two studies have yielded similar results with respect to the
divergence of relatively large bundles in the CA3a region of
NCAM-mutant mice. In contrast, in CA3c and CA3b we did not observe such
splitting after endo N treatment, and in our analysis at least, the
branching observed in this region reflected the 129 strain genetic
background rather than the NCAM mutation (Barber et al., 1974;
Schwegler and Lipp, 1983). However, it is also possible that this
discrepancy between the two studies reflects differences between the
null NCAM mutation and our more restricted removal of PSA or the
NCAM-180 isoform.
More importantly, the additional information we have obtained for fine
ectopic fibers and their associated terminals is valuable in
considering the mechanisms by which PSA-related defects are generated.
In particular, we were struck by the persistent invasion of the
pyramidal cell layer by unfasciculated mossy fiber processes and the
formation of many synapses by these fibers within that layer. These
observations lead us to suggest two cellular mechanisms by which
removal of PSA could have produced the observed effects: (1) an
increase in the number of unfasciculated mossy fibers or collaterals
that can grow into the pyramidal cell layer, and (2) an inhibition of
the withdrawal of a normally transient innervation of this region.
There is evidence in the literature supporting each mechanism, and it
is possible that both are relevant.
At first consideration, an increase in the number of unfasciculated
fibers is not an effect that would be expected from loss of PSA. That
is, at the membrane-molecular level, removal of PSA appears to enhance
cell interactions (Rutishauser, 1992), which in vivo can
lead to an increase in axon-axon fasciculation (Landmesser et al.,
1990; Tang et al., 1994). However, in other contexts, such as the
innervation of the tectum by optic fiber extensions (Yin et al., 1995)
and the outgrowth of spinal cord motor axons in culture (Rutishauser et
al., 1988; Acheson et al., 1991), it has been proposed that PSA removal
preferentially enhances growth cone environment interactions, thus
resulting in the type of defasciculation and ectopic innervation
observed here for mossy fibers. Alternatively, it has been suggested
that PSA might contribute positively to fiber fasciculation, and thus
its absence would result in smaller bundles (Cremer et al., 1997).
The second mechanism, an inhibition of fiber withdrawal by the absence
of PSA, fits well with both the effects of PSA on cell membrane
interactions and the fact that in normal hippocampal development there
is a transient innervation of the pyramidal cell layer by mossy fiber
extensions (Amaral, 1979; Amaral and Dent, 1981). These earlier studies
described Golgi-impregnated extensions arising from mossy fiber
expansions that are similar in morphology to the DiI-labeled fiber
collaterals that we found penetrating into the pyramidal cell layer.
The extensions grew to their maximal length at approxiamtely P14 and
then retracted by P28, suggesting that they are transient structures
associated with hyperinnervation. Furthermore, at the ultrastructural
level the extensions were found to contain many vesicles and to have made synaptic junctions with pyramidal cells with a morphology distinct
from that of typical mossy fiber terminals and similar to those
described here for PSA-positive fibers located in the pyramidal cell
layer. Together, these studies suggest that the PSA-positive fibers in
the pyramidal cell layer are transient mossy fiber collaterals or
extensions, form transient synapse-like junctions with pyramidal cells,
and are subsequently withdrawn. Thus the level of such fibers in the
pyramidal cell layer is likely to represent a steady-state level with
active extension and retraction, and if PSA removal either inhibits the
retraction or stabilizes the extension, then the pattern of ectopic
innervation would be both augmented and persistent.
With respect to stabilization, it is notable that the punctate staining
of PSA on mossy fibers was observed to be negatively correlated with
junction formation in that both adherens and synaptic junctions were
found to be free of PSA. This raises the interesting issue of whether
PSA removal promotes junctional contacts that stabilize the ectopic
processes or whether the persistence of the fibers leads to more
junction formation. In the case of synapses, the fact that the number
of terminals increased from day 15 to 1.5 months in both the endo
N-treated and control animals would seem to argue that persistence by
itself is a factor. Nevertheless, the large mossy
fiber terminals seen in the PSA-negative animals at early stages (P15)
are already distinguishable from the relatively small varicosities
found in normal animals and would be consistent with an active role for
PSA in suppressing junction formation in the pyramidal cell layer.
In sum, the role of PSA in morphological development of hippocampal
mossy fibers appears to be the regulation of an exuberant and transient
outgrowth of collaterals and the formation of synapses by those axons.
Given these findings, the role of PSA during normal development of axon
pathways remains to be considered more broadly. PSA is abundantly
expressed on essentially all growing fiber tracts in the developing
CNS, and thus the effects seen here are likely to be relevant to other
situations. With respect to the transient projection of excessive
numbers of or ectopically placed PSA-positive fibers into their target
tissue, it should be noted that such behavior is quite widespread,
including for example the transient contact of climbing fibers with the
soma of Purkinje cells in the cerebellum (Mason and Gregory, 1984;
Altman and Bayer, 1997), exuberant outgrowth of intracortical axons
followed by a selective pruning of early formed branches
(Gomez-DiCesare et al., 1997), and the polyinnervation of muscles by
motor neurons in the peripheral nervous system (Colman et al., 1997).
If the present findings are relevant, then one would predict that PSA
removal might produce a persistence of such immature fiber patterns
with possible physiological consequences arising from the presence of
inappropriate terminals. In fact, our previous studies on the effects
of endo N on tectal innervation by optic fibers (Yin et al., 1995) may
also require additional interpretation in that the apparent
defasciculation of nerve bundles in the tract and rostral tectum could
have been augmented by a persistence of normally transient axonal
explorations in this region.
Finally, whether the behavioral defects observed in NCAM- or
PSA-deficient mice (Cremer et al., 1994; Becker et al., 1996) might
reflect in part the effects seen here in hippocampus remains to be
addressed. Several potentially valid points can be raised. First,
increases in the innervation of the pyramidal cell layer have been
correlated with a defect in avoidance learning (Lipp et al., 1983).
Second, in the mature hippocampus there are many more synapses in the
CA3 pyramidal cell layer of mutant or endo N-treated animals so that a
morphological correlate of physiological function is at least present
in the adult. Third, innervation of CA3 by PSA-positive mossy fibers
continues through much of adulthood, presumably leading to new
connections (Seki and Arai, 1993b, 1995), and it is reasonable to
expect that loss of this PSA would produce defects related to those
found in development. It should also be noted that in epileptic
animals, there is an aberrant growth of mossy fibers in the pyramidal
cell layer that is similar in appearance to the ectopic fibers observed
in the endo N-treated or NCAM mutant animals (Ben-Ari and Represa,
1990; Parent et al., 1997). Obviously this extrapolation from
development to physiology, not to mention the undefined role of the
hippocampus itself in such behaviors, represents an extended
speculation. In any case, the present study provides both new
information of the cellular basis of PSA function and the first pieces
of information related to the long path between the genetic mutation of
the NCAM gene and its associated behavioral phenotypes.
| |
FOOTNOTES |
Received Dec. 29, 1997; revised March 2, 1998; accepted March 9, 1997.
This work was supported in part by National Institutes of Health Grants
HD18369 and NS32779. T.S. was supported in part by the Yamada Science
Foundation. We thank Lynn Landmesser, Karl Herrup, and Alfred Malouf
for critical reviews of this manuscript.
Correspondence should be addressed to Dr. Urs Rutishauser, Department
of Genetics, Case Western Reserve University, 2109 Adelbert Road,
Cleveland, OH 44106.
| |
REFERENCES |
-
Acheson A,
Sunshine JL,
Rutishauser U
(1991)
NCAM polysialic acid can regulate both cell-cell and cell-substrate interactions.
J Cell Biol
114:143-153[Abstract/Free Full Text].
-
Altman J,
Bayer AS
(1997)
In: Development of the cerebellar system. Boca Raton: CRC.
-
Amaral DG
(1979)
Synaptic extensions from the mossy fibers of the fascia dentata.
Anat Embryol (Berl)
155:241-251[Medline].
-
Amaral DG,
Dent JA
(1981)
Development of the mossy fibers of the dentate gyrus. I. A light and electron microscopic study of the mossy fibers and their expansions.
J Comp Neurol
195:51-86[Web of Science][Medline].
-
Barber RP,
Vaughn JE,
Wimer RE,
Wimer CC
(1974)
Genetically-associated variations in the distribution of dentate granule cell synapses upon the pyramidal cell dendrites in mouse hippocampus.
J Comp Neurol
156:417-434[Web of Science][Medline].
-
Bartheld CS,
Cunningham DE,
Rubel E
(1990)
Neuronal tracing with DiI: decalcification, cryosectioning, and photoconversion for light and electron microscopic analysis.
J Histochem Cytochem
38:725-733[Abstract].
-
Becker CG,
Artola A,
Gerardy-Schahn R,
Becker T,
Welzl H,
Schachner M
(1996)
The polysialic acid modification of the neural cell adhesion molecule is involved in spatial learning and hippocampal long-term potentiation.
J Neurosci Res
45:143-152[Web of Science][Medline].
-
Ben-Ari Y,
Represa A
(1990)
Brief seizure episodes induce long-term potentiation and mossy fiber sprouting in the hippocampus.
Trends Neurosci
13:312-318[Web of Science][Medline].
-
Bofanti L,
Olive S,
Poulain DA,
Theodosis DT
(1992)
Mapping of the distribution of polysialylated neural cell adhesion molecule throughout the central nervous system of the adult rat: an immunohistochemical study.
Neuroscience
49:419-436[Web of Science][Medline].
-
Colman H,
Nabekura J,
Lichtman JW
(1997)
Alterations in synaptic strength preceding axon withdrawal.
Science
275:356-361[Abstract/Free Full Text].
-
Cremer H,
Lange R,
Christoph A,
Plomann M,
Vopper G,
Roes J,
Brown R,
Baldwin S,
Kraemer P,
Scheff S,
Dagmar B,
Rajewsky K,
Will W
(1994)
Inactivation of the N-CAM gene in mice results in size reduction of the olfactory bulb and deficits in spatial learning.
Nature
367:455-459[Medline].
-
Cremer H,
Chazal G,
Goridis C,
Represa A
(1997)
NCAM is essential for axonal growth and fasciculation in the hippocampus.
Mol Cell Neurosci
8:323-335[Web of Science][Medline].
-
Daston MM,
Bastmeyer M,
Rutishauser U,
O'Leary DM
(1996)
Spatially restricted increase in polysialic acid enhances corticospinal axon branching related to target recognition and innervation.
J Neurosci
16:5488-5497[Abstract/Free Full Text].
-
Gaarskjaer FB
(1985)
The development of the dentate area and the hippocampal mossy fiber projection of the rat.
J Comp Neurol
241:154-170[Web of Science][Medline].
-
Gomez-DiCesare CM,
Smith K,
Rice FL,
Swann JW
(1997)
Axonal remodeling during postnatal maturation of CA3 hippocampal pyramidal neurons.
J Comp Neurol
384:165-180[Web of Science][Medline].
-
Hallenbeck PC,
Vimr ER,
Yu F,
Bassler B,
Troy FA
(1987)
Purification and properties of a bacteriophage-induced endo-N-acetylneuraminidase specific for poly-
 -2,8-sialosyl carbohydrate units.
J Biol Chem
262:3553-3561[Abstract/Free Full Text]. -
Ishizuka N,
Weber J,
Amaral D
(1990)
Organization of intrahippocampal projections originating from CA3 pyramidal cells in the rat.
J Comp Neurol
195:580-623.
-
Landmesser L,
Dahm L,
Tang J,
Rutishauser U
(1990)
Polysialic acid as a regulator of intramuscular nerve branching during embryonic development.
Neuron
4:655-667[Web of Science][Medline].
-
Lipp HP,
Schwegler H,
Driscoll P
(1983)
Postnatal modification of hippocampal circuitry alters avoidance learning in adult rats.
Science
225:80-82.
-
Mason CA,
Gregory E
(1984)
Postnatal maturation of cerebellar mossy and climbing fibers: transient expression of dual features on single axons.
J Neurosci
4:1715-1735[Abstract].
-
Muller D,
Wang C,
Skibo G,
Toni N,
Cremer H,
Calaora V,
Rougon G,
Kiss JZ
(1996)
PSA-NCAM is required for activity-induced synaptic plasticity.
Neuron
17:413-422[Web of Science][Medline].
-
Ono K,
Tomasiewicz H,
Magnuson T,
Rutishauser U
(1994)
NCAM mutation inhibits tangential neuronal migration and is phenocopied by enzymatic removal of polysialic acid.
Neuron
13:595-609[Web of Science][Medline].
-
Parent JM,
Yu TW,
Leibowitz RT,
Geschwind DH,
Sloviter RS,
Lowenstein DH
(1997)
Dentate granule cell neurogenesis is increased by seizures and contributes to aberrant network reorganization in the adult rat hippocampus.
J Neurosci
17:3727-3738[Abstract/Free Full Text].
-
Rutishauser U (1992) NCAM and its polysialic acid moiety: a
mechanism for pull/push regulation of cell interactions during
development? Development [Suppl 1992]:99-104.
-
Rutishauser U,
Landmesser L
(1996)
Polysialic acid in the vertebrate nervous system: a promoter of plasticity in cell-cell interactions.
Trends Neurosci
19:422-427[Web of Science][Medline].
-
Rutishauser U,
Acheson A,
Hall AK,
Mann DM,
Sunshine J
(1988)
The neural cell adhesion molecule (NCAM) as a regulator of cell-cell interactions.
Science
240:53-57[Abstract/Free Full Text].
-
Sato C,
Kitajima K,
Inoue S,
Seki T,
Troy FA,
Inoue Y
(1995)
Characterization of the antigenic specificity of four different anti-(alpha 2-8-linked polysialic acid) antibodies using lipid-conjugated oligo/polysialic acids.
J Biol Chem
270:18923-18928[Abstract/Free Full Text].
-
Schwegler H,
Lipp HP
(1983)
Hereditary covariations of neuronal circuitry and behavior: correlations between the proportions of hippocampal synaptic fields in the regio inferior and two-way avoidance in mice and rats.
Behav Brain Res
7:1-38[Web of Science][Medline].
-
Seki T,
Arai Y
(1991a)
Expression of highly polysialylated NCAM in the neocortex and piriform cortex of the developing and the adult rat.
Anat Embryol (Berl)
184:395-401[Medline].
-
Seki T,
Arai Y
(1991b)
The persistent expression of a highly polysialylated NCAM in the dentate gyrus of the adult rat.
Neurosci Res
12:503-513[Web of Science][Medline].
-
Seki T,
Arai Y
(1993a)
Distribution and possible roles of the highly polysialylated neural cell adhesion molecule (NCAM-H) in the developing and adult central nervous system.
Neurosci Res
17:265-290[Web of Science][Medline].
-
Seki T,
Arai Y
(1993b)
Highly polysialylated neural cell adhesion molecule (NCAM-H) is expressed by newly generated granule cells in the dentate gyrus of the adult rat.
J Neurosci
13:2351-2358[Abstract].
-
Seki T,
Arai Y
(1995)
Age-related production of new granule cells in the adult dentate gyrus.
NeuroReport
6:2479-2482[Web of Science][Medline].
-
Shen H,
Watanabe M,
Tomasiewicz H,
Rutishauser U,
Magnuson T,
Glass JD
(1977)
Role of neural cell adhesion molecule and polysialic acid in mouse circadian clock function.
J Neurosci
17:5221-5229[Abstract/Free Full Text].
-
Tang J,
Rutishauser U,
Landmesser L
(1994)
Polysialic acid regulates growth cone behavior during sorting of motor axons in the plexus region.
Neuron
13:405-414[Web of Science][Medline].
-
Theodosis DT,
Rougon G,
Poulain DA
(1991)
Retention of embryonic features by an adult neuronal system capable of plasticity: polysialylated neural cell adhesion molecule in the hypothalamo-neurohypophysical system.
Proc Natl Acad Sci USA
88:5494-5498[Abstract/Free Full Text].
-
Tomasiewics H,
Ono K,
Yee D,
Thompson C,
Goridis C,
Rutishauser U,
Magnuson T
(1994)
Genetic deletion of a neural cell adhesion molecule variant (N-CAM-180) produces distinct defects in the central nervous system.
Neuron
11:1163-1174.
-
Yin X,
Watanabe M,
Rutishauser U
(1995)
Effect of polysialic acid on the behavior of retinal ganglion cell axons during growth into the optic tract and tectum.
Development
121:3439-3446[Abstract].
Copyright © 1998 Society for Neuroscience 0270-6474/98/18103757-10$05.00/0
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|
|
|
|
|
|
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|
|
|
|
|
|
|
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|
|
|
|
|
|
|
Y. P. Wu, C.-J. Siao, W. Lu, T.-C. Sung, M. A. Frohman, P. Milev, T. H. Bugge, J. L. Degen, J. M. Levine, R. U. Margolis, et al.
The Tissue Plasminogen Activator (Tpa/Plasmin) Extracellular Proteolytic System Regulates Seizure-Induced Hippocampal Mossy Fiber Outgrowth through a Proteoglycan Substrate
J. Cell Biol.,
March 20, 2000;
148(6):
1295 - 1304.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
G. Chazal, P. Durbec, A. Jankovski, G. Rougon, and H. Cremer
Consequences of Neural Cell Adhesion Molecule Deficiency on Cell Migration in the Rostral Migratory Stream of the Mouse
J. Neurosci.,
February 15, 2000;
20(4):
1446 - 1457.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
A. Sawaguchi, Y. Idate, S. Ide, J.-i. Kawano, R. Nagaike, T. Oinuma, and T. Suganuma
Multistratified Expression of Polysialic Acid and Its Relationship to VAChT-containing Neurons in the Inner Plexiform Layer of Adult Rat Retina
J. Histochem. Cytochem.,
July 1, 1999;
47(7):
919 - 928.
[Abstract]
[Full Text]
|
|
|
|
|
|
|
Y. Ikegaya
Abnormal Targeting of Developing Hippocampal Mossy Fibers after Epileptiform Activities via L-type Ca2+ Channel Activation In Vitro
J. Neurosci.,
January 15, 1999;
19(2):
802 - 812.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
H. Cremer, G. Chazal, A. Carleton, C. Goridis, J.-D. Vincent, and P.-M. Lledo
Long-term but not short-term plasticity at mossy fiber synapses is impaired in neural cell adhesion molecule-deficient mice
PNAS,
October 27, 1998;
95(22):
13242 - 13247.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
S. Inoue and Y. Inoue
Developmental Profile of Neural Cell Adhesion Molecule Glycoforms with a Varying Degree of Polymerization of Polysialic Acid Chains
J. Biol. Chem.,
August 17, 2001;
276(34):
31863 - 31870.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
I. Fujimoto, J. L. Bruses, and U. Rutishauser
Regulation of Cell Adhesion by Polysialic Acid. EFFECTS ON CADHERIN, IMMUNOGLOBULIN CELL ADHESION MOLECULE, AND INTEGRIN FUNCTION AND INDEPENDENCE FROM NEURAL CELL ADHESION MOLECULE BINDING OR SIGNALING ACTIVITY
J. Biol. Chem.,
August 17, 2001;
276(34):
31745 - 31751.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
P. Charles, M. P. Hernandez, B. Stankoff, M. S. Aigrot, C. Colin, G. Rougon, B. Zalc, and C. Lubetzki
Negative regulation of central nervous system myelination by polysialylated-neural cell adhesion molecule
PNAS,
June 20, 2000;
97(13):
7585 - 7590.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
Top
Abstract
Introduction
