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Cadherin activity is required for activity-induced spine remodeling.

Okamura K, Tanaka H, Yagita Y, Saeki Y, Taguchi A, Hiraoka Y, Zeng LH, Colman DR, Miki N - J. Cell Biol. (2004)

Bottom Line: N-cadherin-venus fusion protein laterally dispersed along the expanding spine head.Overexpression of dominant-negative forms of N-cadherin resulted in the abrogation of the spine expansion.Inhibition of actin polymerization with cytochalasin D abolished the spine expansion.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Osaka University Medical School, Suita, Japan.

ABSTRACT
Neural activity induces the remodeling of pre- and postsynaptic membranes, which maintain their apposition through cell adhesion molecules. Among them, N-cadherin is redistributed, undergoes activity-dependent conformational changes, and is required for synaptic plasticity. Here, we show that depolarization induces the enlargement of the width of spine head, and that cadherin activity is essential for this synaptic rearrangement. Dendritic spines visualized with green fluorescent protein in hippocampal neurons showed an expansion by the activation of AMPA receptor, so that the synaptic apposition zone may be expanded. N-cadherin-venus fusion protein laterally dispersed along the expanding spine head. Overexpression of dominant-negative forms of N-cadherin resulted in the abrogation of the spine expansion. Inhibition of actin polymerization with cytochalasin D abolished the spine expansion. Together, our data suggest that cadherin-based adhesion machinery coupled with the actin-cytoskeleton is critical for the remodeling of synaptic apposition zone.

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Remodeling of spine in N-cadherin transfected neuron. Neurons were doubly transfected with gfp and N-cadherin-myc and subjected to time-lapse imaging. (A) Retrospective immunostaining with anti-myc antibody confirms that the green neuron overexpresses N-cadherin-myc. N-cadherin-myc is accumulated in spines. (B) Time-lapse imaging of the N-cadherin-myc transfected neuron before, during and after a 2-min depolarization. Spines display rounding up during the depolarization, and the lateral enlargement during the recovery phase. B′ depict magnified images. (C) The SCCL of each spine before and 30 min after depolarization is plotted. The measurements of 42 spines of four neurons (dendrites) were collected from four independent experiments. *P < 0.0000004. Bar: (A) 5.00 μm; (B) 7.33 μm; (B′) 2.00 μm.
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fig6: Remodeling of spine in N-cadherin transfected neuron. Neurons were doubly transfected with gfp and N-cadherin-myc and subjected to time-lapse imaging. (A) Retrospective immunostaining with anti-myc antibody confirms that the green neuron overexpresses N-cadherin-myc. N-cadherin-myc is accumulated in spines. (B) Time-lapse imaging of the N-cadherin-myc transfected neuron before, during and after a 2-min depolarization. Spines display rounding up during the depolarization, and the lateral enlargement during the recovery phase. B′ depict magnified images. (C) The SCCL of each spine before and 30 min after depolarization is plotted. The measurements of 42 spines of four neurons (dendrites) were collected from four independent experiments. *P < 0.0000004. Bar: (A) 5.00 μm; (B) 7.33 μm; (B′) 2.00 μm.

Mentions: To rule out the possible artifact by the overexpression of N-cadherin in the experiments above, we examined the effect of overexpression of N-cadherin on the change in spine shape. We cotransfected N-cadherin and gfp cDNAs into cultured neurons, and confirmed that the green neurons coexpressed abundant recombinant N-cadherin by immunostaining retrospectively (Fig. 6 A). 57% of the dendritic protrusions displayed typical cotyloid spine, whereas only 16% were filopodia (Table I). The data suggest that overexpression of N-cadherin increases the ratio of mature spine and decrease the ratio of filopodia. However, the total number, and the mean length of the protrusions were not changed by the overexpression of N-cadherin (Fig. 7 D; Table II). The morphological responses to membrane depolarization were essentially the same as in the control neurons; the spines rounded up and halted during the depolarization, and became enlarged after the repolarization (Fig. 6 B). The mean SCCL changed from 3.08 ± 0.0975 μm to 4.00 ± 0.134 μm in 30 min of recovery (Fig. 6 C). The extent of the spine enlargement was similar to that in control neurons (1.32× enlargement of SCCL, SEM = 0.0359; Fig. 7 J).


Cadherin activity is required for activity-induced spine remodeling.

Okamura K, Tanaka H, Yagita Y, Saeki Y, Taguchi A, Hiraoka Y, Zeng LH, Colman DR, Miki N - J. Cell Biol. (2004)

Remodeling of spine in N-cadherin transfected neuron. Neurons were doubly transfected with gfp and N-cadherin-myc and subjected to time-lapse imaging. (A) Retrospective immunostaining with anti-myc antibody confirms that the green neuron overexpresses N-cadherin-myc. N-cadherin-myc is accumulated in spines. (B) Time-lapse imaging of the N-cadherin-myc transfected neuron before, during and after a 2-min depolarization. Spines display rounding up during the depolarization, and the lateral enlargement during the recovery phase. B′ depict magnified images. (C) The SCCL of each spine before and 30 min after depolarization is plotted. The measurements of 42 spines of four neurons (dendrites) were collected from four independent experiments. *P < 0.0000004. Bar: (A) 5.00 μm; (B) 7.33 μm; (B′) 2.00 μm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2172468&req=5

fig6: Remodeling of spine in N-cadherin transfected neuron. Neurons were doubly transfected with gfp and N-cadherin-myc and subjected to time-lapse imaging. (A) Retrospective immunostaining with anti-myc antibody confirms that the green neuron overexpresses N-cadherin-myc. N-cadherin-myc is accumulated in spines. (B) Time-lapse imaging of the N-cadherin-myc transfected neuron before, during and after a 2-min depolarization. Spines display rounding up during the depolarization, and the lateral enlargement during the recovery phase. B′ depict magnified images. (C) The SCCL of each spine before and 30 min after depolarization is plotted. The measurements of 42 spines of four neurons (dendrites) were collected from four independent experiments. *P < 0.0000004. Bar: (A) 5.00 μm; (B) 7.33 μm; (B′) 2.00 μm.
Mentions: To rule out the possible artifact by the overexpression of N-cadherin in the experiments above, we examined the effect of overexpression of N-cadherin on the change in spine shape. We cotransfected N-cadherin and gfp cDNAs into cultured neurons, and confirmed that the green neurons coexpressed abundant recombinant N-cadherin by immunostaining retrospectively (Fig. 6 A). 57% of the dendritic protrusions displayed typical cotyloid spine, whereas only 16% were filopodia (Table I). The data suggest that overexpression of N-cadherin increases the ratio of mature spine and decrease the ratio of filopodia. However, the total number, and the mean length of the protrusions were not changed by the overexpression of N-cadherin (Fig. 7 D; Table II). The morphological responses to membrane depolarization were essentially the same as in the control neurons; the spines rounded up and halted during the depolarization, and became enlarged after the repolarization (Fig. 6 B). The mean SCCL changed from 3.08 ± 0.0975 μm to 4.00 ± 0.134 μm in 30 min of recovery (Fig. 6 C). The extent of the spine enlargement was similar to that in control neurons (1.32× enlargement of SCCL, SEM = 0.0359; Fig. 7 J).

Bottom Line: N-cadherin-venus fusion protein laterally dispersed along the expanding spine head.Overexpression of dominant-negative forms of N-cadherin resulted in the abrogation of the spine expansion.Inhibition of actin polymerization with cytochalasin D abolished the spine expansion.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Osaka University Medical School, Suita, Japan.

ABSTRACT
Neural activity induces the remodeling of pre- and postsynaptic membranes, which maintain their apposition through cell adhesion molecules. Among them, N-cadherin is redistributed, undergoes activity-dependent conformational changes, and is required for synaptic plasticity. Here, we show that depolarization induces the enlargement of the width of spine head, and that cadherin activity is essential for this synaptic rearrangement. Dendritic spines visualized with green fluorescent protein in hippocampal neurons showed an expansion by the activation of AMPA receptor, so that the synaptic apposition zone may be expanded. N-cadherin-venus fusion protein laterally dispersed along the expanding spine head. Overexpression of dominant-negative forms of N-cadherin resulted in the abrogation of the spine expansion. Inhibition of actin polymerization with cytochalasin D abolished the spine expansion. Together, our data suggest that cadherin-based adhesion machinery coupled with the actin-cytoskeleton is critical for the remodeling of synaptic apposition zone.

Show MeSH
Related in: MedlinePlus