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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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Depolarization induces the lateral expansion of spine head. Hippocampal neurons were transfected with gfp and subjected to CCD imaging on 18–22 DIV. (A) GFP uniformly labels the neuronal contour. (B) Closer magnification of a GFP-filled dendrite. Closed arrow, cotyloid spine; closed arrowhead, flat apex spine; open arrow, thin spine; open arrowhead, filopodium (Table I; Fig. 7 C). (C) The GFP-filled neurons were immunolabeled with synaptophysin (red). The presynaptic terminal labeled by synaptophysin attaches to the cotyloid face on the apex of the spine. Arrowheads indicate putative synaptic cleft. (D) GFP-labeled neurons were transiently treated with high K+ (31 mM) for 2 min, and recovered for 60 min in normal K+ solution, while images were taken serially. The spine rounded up during the depolarization (2 min), and then displayed cotyloid shape again when the stimulation was halted (recovery 5′). The lateral size of the spine became larger than in the original at 15 min after the stimulation (recovery 15′), and it lasted at least for 60 min (recovery 60′). Bar: (A) 60.00 μm; (B) 5.00 μm; (C) 1.00 μm; (D) 1.25 μm.
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fig1: Depolarization induces the lateral expansion of spine head. Hippocampal neurons were transfected with gfp and subjected to CCD imaging on 18–22 DIV. (A) GFP uniformly labels the neuronal contour. (B) Closer magnification of a GFP-filled dendrite. Closed arrow, cotyloid spine; closed arrowhead, flat apex spine; open arrow, thin spine; open arrowhead, filopodium (Table I; Fig. 7 C). (C) The GFP-filled neurons were immunolabeled with synaptophysin (red). The presynaptic terminal labeled by synaptophysin attaches to the cotyloid face on the apex of the spine. Arrowheads indicate putative synaptic cleft. (D) GFP-labeled neurons were transiently treated with high K+ (31 mM) for 2 min, and recovered for 60 min in normal K+ solution, while images were taken serially. The spine rounded up during the depolarization (2 min), and then displayed cotyloid shape again when the stimulation was halted (recovery 5′). The lateral size of the spine became larger than in the original at 15 min after the stimulation (recovery 15′), and it lasted at least for 60 min (recovery 60′). Bar: (A) 60.00 μm; (B) 5.00 μm; (C) 1.00 μm; (D) 1.25 μm.

Mentions: To study the morphological plasticity of postsynaptic spine, we performed time-lapse video imaging of cultured hippocampal neurons visualized with GFP. Rat neurons isolated from embryonic day 18 embryos were transfected with the cDNA for gfp on the sixth day in vitro (DIV), and subjected to time-lapse charge-coupled imaging device (CCD) imaging on 18–22 DIV, when dendrites display numerous mature spines (Fig. 1 A). The GFP diffusely distributed through cytoplasm, and labeled the contour of dendritic protrusions. At this stage, 49% of the protrusions appeared on dendritic surface showed cotyloid appearance (Fig. 1 B, closed arrow), and 17% showed flat-apex mushroom appearance (closed arrowhead; Table I). These two types are the ones classically recognized as typical mature spines with bulged heads connected to the dendritic shaft with short necks. There were also thin spines with long necks (Fig. 1 B, open arrow; 12%), and filopodia (Fig. 1 B, open arrowhead; 22%; Table I). The cotyloid spine top was closely apposed to a presynaptic terminus labeled by synaptophysin, suggesting that this surface forms an adhesive contact with the presynaptic membrane (Fig. 1 C).


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)

Depolarization induces the lateral expansion of spine head. Hippocampal neurons were transfected with gfp and subjected to CCD imaging on 18–22 DIV. (A) GFP uniformly labels the neuronal contour. (B) Closer magnification of a GFP-filled dendrite. Closed arrow, cotyloid spine; closed arrowhead, flat apex spine; open arrow, thin spine; open arrowhead, filopodium (Table I; Fig. 7 C). (C) The GFP-filled neurons were immunolabeled with synaptophysin (red). The presynaptic terminal labeled by synaptophysin attaches to the cotyloid face on the apex of the spine. Arrowheads indicate putative synaptic cleft. (D) GFP-labeled neurons were transiently treated with high K+ (31 mM) for 2 min, and recovered for 60 min in normal K+ solution, while images were taken serially. The spine rounded up during the depolarization (2 min), and then displayed cotyloid shape again when the stimulation was halted (recovery 5′). The lateral size of the spine became larger than in the original at 15 min after the stimulation (recovery 15′), and it lasted at least for 60 min (recovery 60′). Bar: (A) 60.00 μm; (B) 5.00 μm; (C) 1.00 μm; (D) 1.25 μm.
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Related In: Results  -  Collection

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fig1: Depolarization induces the lateral expansion of spine head. Hippocampal neurons were transfected with gfp and subjected to CCD imaging on 18–22 DIV. (A) GFP uniformly labels the neuronal contour. (B) Closer magnification of a GFP-filled dendrite. Closed arrow, cotyloid spine; closed arrowhead, flat apex spine; open arrow, thin spine; open arrowhead, filopodium (Table I; Fig. 7 C). (C) The GFP-filled neurons were immunolabeled with synaptophysin (red). The presynaptic terminal labeled by synaptophysin attaches to the cotyloid face on the apex of the spine. Arrowheads indicate putative synaptic cleft. (D) GFP-labeled neurons were transiently treated with high K+ (31 mM) for 2 min, and recovered for 60 min in normal K+ solution, while images were taken serially. The spine rounded up during the depolarization (2 min), and then displayed cotyloid shape again when the stimulation was halted (recovery 5′). The lateral size of the spine became larger than in the original at 15 min after the stimulation (recovery 15′), and it lasted at least for 60 min (recovery 60′). Bar: (A) 60.00 μm; (B) 5.00 μm; (C) 1.00 μm; (D) 1.25 μm.
Mentions: To study the morphological plasticity of postsynaptic spine, we performed time-lapse video imaging of cultured hippocampal neurons visualized with GFP. Rat neurons isolated from embryonic day 18 embryos were transfected with the cDNA for gfp on the sixth day in vitro (DIV), and subjected to time-lapse charge-coupled imaging device (CCD) imaging on 18–22 DIV, when dendrites display numerous mature spines (Fig. 1 A). The GFP diffusely distributed through cytoplasm, and labeled the contour of dendritic protrusions. At this stage, 49% of the protrusions appeared on dendritic surface showed cotyloid appearance (Fig. 1 B, closed arrow), and 17% showed flat-apex mushroom appearance (closed arrowhead; Table I). These two types are the ones classically recognized as typical mature spines with bulged heads connected to the dendritic shaft with short necks. There were also thin spines with long necks (Fig. 1 B, open arrow; 12%), and filopodia (Fig. 1 B, open arrowhead; 22%; Table I). The cotyloid spine top was closely apposed to a presynaptic terminus labeled by synaptophysin, suggesting that this surface forms an adhesive contact with the presynaptic membrane (Fig. 1 C).

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