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. Author manuscript; available in PMC: 2016 Jan 7.
Published in final edited form as: Neuron. 2015 Jan 7;85(1):173–189. doi: 10.1016/j.neuron.2014.12.023

Figure 1. Dynamic Dispersion of SynGAP from Spines during LTP.

Figure 1

(A) Dispersion of SynGAP from synapses upon LTP stimulation. GFP-tagged SynGAP was dynamically dispersed upon LTP. mCherry was used as a morphology marker to show spine enlargement during LTP. Enlarged spines (e.g., spines 1–4) dispersed SynGAP. Some “no-response spines” (e.g., spines a–b) failed to disperse SynGAP. Correlations are shown in (D). Scale bar, 5 μm.

(B) Time course of averages of all spine size changes and SynGAP dispersion during LTP (n = 3 independent experiments/neurons that contain 35 spines).

(C) PSD fractionation during LTP also showed dynamic SynGAP dispersion from PSDs during LTP. Error bars indicate ± SEM.

(D) The relationship of “Dispersion of SynGAP from spine” and “Spine enlargement” in sustained phase (60 min) showed a strong and significant positive correlation between SynGAP dispersion and spine enlargement (n = 91 spines from seven independent experiments/neurons, R2 = 0.7288, p < 0.01). Spines 1–4 and a–b in (A) are also displayed. Note that the y intercept of trend line is nearly zero, showing that there was no spine enlargement if the spine failed to disperse SynGAP.

(E) Effects of pharmacological inhibition of “NMDAR-CaMKII,” “small G proteins,” and “actin polymerization” on Spine volume and SynGAP dispersion in the Sustained phase (60 min) (Spine volume: Drug F(9, 40) = 23.97, p < 0.001; SynGAP dispersion: Drug F(9, 40) = 28.00, p < 0.001). These results showed NMDAR-CaMKII pathway involved both in spine enlargement and SynGAP dispersion. Inhibition of “small G proteins, downstream kinase” and “actin polymerization” inhibited spine enlargement but not SynGAP dispersion, suggesting SynGAP dispersion is upstream cellular process of small G protein activation and actin polymerization. Error bars indicate ± SEM.

(F) Effects of pharmacological inhibition of “NMDAR-CaMKII,” “small G proteins,” and “actin polymerization” on Spine volume and SynGAP dispersion in the Acute phase (10 min) (Spine volume: Drug F(9, 40) = 42.13, p < 0.001; SynGAP dispersion: Drug F(9, 40) = 17.44, p < 0.001). Note that spine size enlargement was insensitive to CaMKII inhibition, Rac1 inhibition, and low dose of Latrunculin A (20 nM) treatment only in Acute phase, whereas SynGAP dispersion was still inhibited by CaMKII inhibition also in acute phase, suggesting CaMKII activity is essential for SynGAP dispersion (n = 5 independent experiments/neurons in all conditions, which contain 61 [Ctrl], 60 [APV], 52 [W7], 48 [KN62-4 μM], 50 [KN62-20 μM], 59 [RasDN], 62 [RacDN], 60 [G1152], 51 [LatA-20nM], and 60 [LatA-100nM] spines in total, respectively). Error bars indicate ± SEM.