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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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Involvement of cadherin/actin complex in the rearrangement and the maintenance of spine structure. (A–C) The activity-induced spine expansion is dependent on actin polymerization. Cytochalasin D was applied 30 min before and during imaging (A). The transient rounding up of spines during the depolarization was not affected by cytochalasin D treatment (A, depol). The spine expansion during the recovery phase was inhibited by cytochalasin D treatment (A, recovery 15′–30′). The SCCL of each spine before and 30 min after depolarization is plotted (B). The ratios between resting SCCL and stimulated (30 min) SCCL are shown (C; mean ± SEM). *P < 0.05 to the control. The data were collected from four to five neurons (dendrites) in four to five independent experiments. (D) During (depol) and after the depolarization (recovery 5′), the W2A-cadherin transfected neurons protruded filopodia-like structures on the top of the spines (arrows). These protrusions then fuse with each other and retract while moving in various directions (recovery 30′). (E) The neuron was preincubated (30 min) and imaged with existence of latrunculin B. Note that filopodia-like structures formed on the spine top (arrowheads). Bar: (A) 1.47 μm; (D) 2.35 μm; (E) 2.50 μm.
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fig8: Involvement of cadherin/actin complex in the rearrangement and the maintenance of spine structure. (A–C) The activity-induced spine expansion is dependent on actin polymerization. Cytochalasin D was applied 30 min before and during imaging (A). The transient rounding up of spines during the depolarization was not affected by cytochalasin D treatment (A, depol). The spine expansion during the recovery phase was inhibited by cytochalasin D treatment (A, recovery 15′–30′). The SCCL of each spine before and 30 min after depolarization is plotted (B). The ratios between resting SCCL and stimulated (30 min) SCCL are shown (C; mean ± SEM). *P < 0.05 to the control. The data were collected from four to five neurons (dendrites) in four to five independent experiments. (D) During (depol) and after the depolarization (recovery 5′), the W2A-cadherin transfected neurons protruded filopodia-like structures on the top of the spines (arrows). These protrusions then fuse with each other and retract while moving in various directions (recovery 30′). (E) The neuron was preincubated (30 min) and imaged with existence of latrunculin B. Note that filopodia-like structures formed on the spine top (arrowheads). Bar: (A) 1.47 μm; (D) 2.35 μm; (E) 2.50 μm.

Mentions: The rapid motility of spines is dependent on actin polymerization (Fischer et al., 1998). In addition, cadherin-based adhesion is dependent on linkage to the actin-cytoskeleton, bridged by β- and α-catenins (Gumbiner and McCrea, 1993). Therefore, we examined if the cadherin-dependent spine remodeling is associated with the actin polymerization. Low concentration of cytochalasin D arrests spine motility without significant depolymerization of preexisting actin fibers (Fischer et al., 1998). In the presence of 40 nM cytochalasin D, spines showed rounding up during depolarization, suggesting that the phenomenon is not dependent on actin polymerization (Fig. 8 A). In contrast, no enlargement of the spines was observed during the recovery phase in the presence of cytochalasin D (Fig. 8, A–C). The mean SCCL being 3.14 ± 0.102 μm at rest remained at 3.33 ± 0.137 μm in 30 min of recovery in the presence of cytochalasin D. The data indicate that the activity-induced expansion of spines is dependent on the remodeling of the actin-cytoskeleton, as well as its surface partner, the cadherins.


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)

Involvement of cadherin/actin complex in the rearrangement and the maintenance of spine structure. (A–C) The activity-induced spine expansion is dependent on actin polymerization. Cytochalasin D was applied 30 min before and during imaging (A). The transient rounding up of spines during the depolarization was not affected by cytochalasin D treatment (A, depol). The spine expansion during the recovery phase was inhibited by cytochalasin D treatment (A, recovery 15′–30′). The SCCL of each spine before and 30 min after depolarization is plotted (B). The ratios between resting SCCL and stimulated (30 min) SCCL are shown (C; mean ± SEM). *P < 0.05 to the control. The data were collected from four to five neurons (dendrites) in four to five independent experiments. (D) During (depol) and after the depolarization (recovery 5′), the W2A-cadherin transfected neurons protruded filopodia-like structures on the top of the spines (arrows). These protrusions then fuse with each other and retract while moving in various directions (recovery 30′). (E) The neuron was preincubated (30 min) and imaged with existence of latrunculin B. Note that filopodia-like structures formed on the spine top (arrowheads). Bar: (A) 1.47 μm; (D) 2.35 μm; (E) 2.50 μm.
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fig8: Involvement of cadherin/actin complex in the rearrangement and the maintenance of spine structure. (A–C) The activity-induced spine expansion is dependent on actin polymerization. Cytochalasin D was applied 30 min before and during imaging (A). The transient rounding up of spines during the depolarization was not affected by cytochalasin D treatment (A, depol). The spine expansion during the recovery phase was inhibited by cytochalasin D treatment (A, recovery 15′–30′). The SCCL of each spine before and 30 min after depolarization is plotted (B). The ratios between resting SCCL and stimulated (30 min) SCCL are shown (C; mean ± SEM). *P < 0.05 to the control. The data were collected from four to five neurons (dendrites) in four to five independent experiments. (D) During (depol) and after the depolarization (recovery 5′), the W2A-cadherin transfected neurons protruded filopodia-like structures on the top of the spines (arrows). These protrusions then fuse with each other and retract while moving in various directions (recovery 30′). (E) The neuron was preincubated (30 min) and imaged with existence of latrunculin B. Note that filopodia-like structures formed on the spine top (arrowheads). Bar: (A) 1.47 μm; (D) 2.35 μm; (E) 2.50 μm.
Mentions: The rapid motility of spines is dependent on actin polymerization (Fischer et al., 1998). In addition, cadherin-based adhesion is dependent on linkage to the actin-cytoskeleton, bridged by β- and α-catenins (Gumbiner and McCrea, 1993). Therefore, we examined if the cadherin-dependent spine remodeling is associated with the actin polymerization. Low concentration of cytochalasin D arrests spine motility without significant depolymerization of preexisting actin fibers (Fischer et al., 1998). In the presence of 40 nM cytochalasin D, spines showed rounding up during depolarization, suggesting that the phenomenon is not dependent on actin polymerization (Fig. 8 A). In contrast, no enlargement of the spines was observed during the recovery phase in the presence of cytochalasin D (Fig. 8, A–C). The mean SCCL being 3.14 ± 0.102 μm at rest remained at 3.33 ± 0.137 μm in 30 min of recovery in the presence of cytochalasin D. The data indicate that the activity-induced expansion of spines is dependent on the remodeling of the actin-cytoskeleton, as well as its surface partner, the cadherins.

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