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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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FRAP analysis to measure the mobility of soluble GFP in spine. Neurons were transfected with GFP+mock (A and C) or GFP+W2A-cadherin (B) and subjected to FRAP analyses. Cytochalasin D was applied 30 min before FRAP (C). Spines were imaged over time with 788-ms intervals. Circles (red) represent means, diamonds (blue) indicate individual data sets. F/Finitial, total fluorescence divided by the initial fluorescence.
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fig9: FRAP analysis to measure the mobility of soluble GFP in spine. Neurons were transfected with GFP+mock (A and C) or GFP+W2A-cadherin (B) and subjected to FRAP analyses. Cytochalasin D was applied 30 min before FRAP (C). Spines were imaged over time with 788-ms intervals. Circles (red) represent means, diamonds (blue) indicate individual data sets. F/Finitial, total fluorescence divided by the initial fluorescence.

Mentions: There is possibility that the change in shape of GFP-filled spine is interfered by the alteration of the diffusion rate of soluble GFP. The change in molecular diffusion rate in response to synaptic activity has been observed in the case with the membrane bound form of the GFP (Richards et al., 2004). To assess the extent of the possible influence due to the diffusion rates of GFP, we have performed FRAP experiments in GFP-filled spines under various conditions (Fig. 9). In either condition, the diffusion of soluble GFP was so rapid that we observed subsecond recovery curves as reported previously (Majewska et al., 2000). There was no detectable difference in the FRAP of cadherin-inactivated neurons (Fig. 9 B). Although there was some delay in recovery with the addition of cytochalasin D, submaximal recovery was achieved within 1 s (Fig. 9 C). Therefore, the change in spine size may not be interfered by the diffusion rate of GFP. Moreover, we observed rapid spine motility both before and after depolarization. This suggests that the GFP diffusion was rapid enough to fill the moving spine in this time course. Therefore, the shape change of GFP-filled spine in control, N-cadherin inactivated, and cytochalasin D–treated neurons likely reflect the actual change in spine shape.


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)

FRAP analysis to measure the mobility of soluble GFP in spine. Neurons were transfected with GFP+mock (A and C) or GFP+W2A-cadherin (B) and subjected to FRAP analyses. Cytochalasin D was applied 30 min before FRAP (C). Spines were imaged over time with 788-ms intervals. Circles (red) represent means, diamonds (blue) indicate individual data sets. F/Finitial, total fluorescence divided by the initial fluorescence.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172468&req=5

fig9: FRAP analysis to measure the mobility of soluble GFP in spine. Neurons were transfected with GFP+mock (A and C) or GFP+W2A-cadherin (B) and subjected to FRAP analyses. Cytochalasin D was applied 30 min before FRAP (C). Spines were imaged over time with 788-ms intervals. Circles (red) represent means, diamonds (blue) indicate individual data sets. F/Finitial, total fluorescence divided by the initial fluorescence.
Mentions: There is possibility that the change in shape of GFP-filled spine is interfered by the alteration of the diffusion rate of soluble GFP. The change in molecular diffusion rate in response to synaptic activity has been observed in the case with the membrane bound form of the GFP (Richards et al., 2004). To assess the extent of the possible influence due to the diffusion rates of GFP, we have performed FRAP experiments in GFP-filled spines under various conditions (Fig. 9). In either condition, the diffusion of soluble GFP was so rapid that we observed subsecond recovery curves as reported previously (Majewska et al., 2000). There was no detectable difference in the FRAP of cadherin-inactivated neurons (Fig. 9 B). Although there was some delay in recovery with the addition of cytochalasin D, submaximal recovery was achieved within 1 s (Fig. 9 C). Therefore, the change in spine size may not be interfered by the diffusion rate of GFP. Moreover, we observed rapid spine motility both before and after depolarization. This suggests that the GFP diffusion was rapid enough to fill the moving spine in this time course. Therefore, the shape change of GFP-filled spine in control, N-cadherin inactivated, and cytochalasin D–treated neurons likely reflect the actual change in spine shape.

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