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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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Evaluation of spine remodeling on deconvolution and conventional microscopy. (A) Capturing CCD images at short intervals demonstrate rapid movement of a spine. (B) Comparison of a raw CCD image (top) with a deconvoluted image (bottom) of spine. (Right) Thresholded images at half maximal fluorescence intensity. (C) Discernment of the (a) spine width, (b) spine length, and (c) SCCL. (D) Dimensions measured on raw CCD images were plotted against those measured on deconvoluted images. R2 = 0.944 (width), R2 = 0.986 (length), R2= 0.965 (SCCL). (E) The spine width (left) and length (right) of each spine before and 30 min after depolarization are plotted. *P < 0.001. (F) A spine with deeply curved apex. Note that the apex curve extends longitudinally. (G) SCCL of each spine before and 30 min after depolarization are plotted. **P < 0.0006. (H) The ratios between resting spine parameters and stimulated (30 min) spine parameters are shown (mean ± SEM). (I) Temporal profiles of the SCCL of each spine. The SCCL of each spine peaks between 15 and 30 min after the stimulation. The measurements of 26 spines of five neurons (dendrites) were collected from five independent experiments (E, G, and H). Bar: (A) 1.52 μm; (B) 1.40 μm; (F) 1.50 μm.
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fig3: Evaluation of spine remodeling on deconvolution and conventional microscopy. (A) Capturing CCD images at short intervals demonstrate rapid movement of a spine. (B) Comparison of a raw CCD image (top) with a deconvoluted image (bottom) of spine. (Right) Thresholded images at half maximal fluorescence intensity. (C) Discernment of the (a) spine width, (b) spine length, and (c) SCCL. (D) Dimensions measured on raw CCD images were plotted against those measured on deconvoluted images. R2 = 0.944 (width), R2 = 0.986 (length), R2= 0.965 (SCCL). (E) The spine width (left) and length (right) of each spine before and 30 min after depolarization are plotted. *P < 0.001. (F) A spine with deeply curved apex. Note that the apex curve extends longitudinally. (G) SCCL of each spine before and 30 min after depolarization are plotted. **P < 0.0006. (H) The ratios between resting spine parameters and stimulated (30 min) spine parameters are shown (mean ± SEM). (I) Temporal profiles of the SCCL of each spine. The SCCL of each spine peaks between 15 and 30 min after the stimulation. The measurements of 26 spines of five neurons (dendrites) were collected from five independent experiments (E, G, and H). Bar: (A) 1.52 μm; (B) 1.40 μm; (F) 1.50 μm.

Mentions: Although the confocal technology enables us to avoid out-of-focus image blurring, it takes at least tens of seconds to collect data of the area that includes several spines, while the spine changes its shape within several seconds (Fischer et al., 1998). To obtain time-lapse images rapidly enough, we collected only a single focus image at each time point with 6-s intervals by the use of a CCD; these experiments confirmed the rapid spine motility (Fig. 3 A). We measured the dimensions of spines from these single-focus images. Measurements of the (a) width, (b) length, and (c) curve of the apex of the spine (spine cotyloid curve length [SCCL]) were performed on thresholded images at half maximal fluorescence intensity (Fig. 3 C). A possible drawback of this procedure, however, is a limited resolution. Therefore, we obtained optical section images of the GFP-filled spines in fixed neurons, and compared undeconvoluted images with deconvoluted ones (Fig. 3 B). In spite of the relatively low resolution of the undeconvoluted images, the dimensions measured on these undeconvoluted images were very well correlated with those measured on the deconvoluted images (Fig. 3 D). For further accuracy, we averaged the values obtained from 21 time series with 6-s intervals for each time window of 2 min.


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)

Evaluation of spine remodeling on deconvolution and conventional microscopy. (A) Capturing CCD images at short intervals demonstrate rapid movement of a spine. (B) Comparison of a raw CCD image (top) with a deconvoluted image (bottom) of spine. (Right) Thresholded images at half maximal fluorescence intensity. (C) Discernment of the (a) spine width, (b) spine length, and (c) SCCL. (D) Dimensions measured on raw CCD images were plotted against those measured on deconvoluted images. R2 = 0.944 (width), R2 = 0.986 (length), R2= 0.965 (SCCL). (E) The spine width (left) and length (right) of each spine before and 30 min after depolarization are plotted. *P < 0.001. (F) A spine with deeply curved apex. Note that the apex curve extends longitudinally. (G) SCCL of each spine before and 30 min after depolarization are plotted. **P < 0.0006. (H) The ratios between resting spine parameters and stimulated (30 min) spine parameters are shown (mean ± SEM). (I) Temporal profiles of the SCCL of each spine. The SCCL of each spine peaks between 15 and 30 min after the stimulation. The measurements of 26 spines of five neurons (dendrites) were collected from five independent experiments (E, G, and H). Bar: (A) 1.52 μm; (B) 1.40 μm; (F) 1.50 μm.
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fig3: Evaluation of spine remodeling on deconvolution and conventional microscopy. (A) Capturing CCD images at short intervals demonstrate rapid movement of a spine. (B) Comparison of a raw CCD image (top) with a deconvoluted image (bottom) of spine. (Right) Thresholded images at half maximal fluorescence intensity. (C) Discernment of the (a) spine width, (b) spine length, and (c) SCCL. (D) Dimensions measured on raw CCD images were plotted against those measured on deconvoluted images. R2 = 0.944 (width), R2 = 0.986 (length), R2= 0.965 (SCCL). (E) The spine width (left) and length (right) of each spine before and 30 min after depolarization are plotted. *P < 0.001. (F) A spine with deeply curved apex. Note that the apex curve extends longitudinally. (G) SCCL of each spine before and 30 min after depolarization are plotted. **P < 0.0006. (H) The ratios between resting spine parameters and stimulated (30 min) spine parameters are shown (mean ± SEM). (I) Temporal profiles of the SCCL of each spine. The SCCL of each spine peaks between 15 and 30 min after the stimulation. The measurements of 26 spines of five neurons (dendrites) were collected from five independent experiments (E, G, and H). Bar: (A) 1.52 μm; (B) 1.40 μm; (F) 1.50 μm.
Mentions: Although the confocal technology enables us to avoid out-of-focus image blurring, it takes at least tens of seconds to collect data of the area that includes several spines, while the spine changes its shape within several seconds (Fischer et al., 1998). To obtain time-lapse images rapidly enough, we collected only a single focus image at each time point with 6-s intervals by the use of a CCD; these experiments confirmed the rapid spine motility (Fig. 3 A). We measured the dimensions of spines from these single-focus images. Measurements of the (a) width, (b) length, and (c) curve of the apex of the spine (spine cotyloid curve length [SCCL]) were performed on thresholded images at half maximal fluorescence intensity (Fig. 3 C). A possible drawback of this procedure, however, is a limited resolution. Therefore, we obtained optical section images of the GFP-filled spines in fixed neurons, and compared undeconvoluted images with deconvoluted ones (Fig. 3 B). In spite of the relatively low resolution of the undeconvoluted images, the dimensions measured on these undeconvoluted images were very well correlated with those measured on the deconvoluted images (Fig. 3 D). For further accuracy, we averaged the values obtained from 21 time series with 6-s intervals for each time window of 2 min.

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