IQGAP1 stimulates spine formation and increases spine head size.

<p>(A) Confocal image showing an example of a 17 DIV cultured hippocampal neuron transfected with mock plasmid plus GFP (green) and double stained with MAP2 (red). (B) A high magnification view of a dendritic segment from another neuron of the same culture (C) A 3-D reconstruction of dendritic shafts from a sister culture; note the morphology and density of dendritic spines. (D–G) Confocal images showing a dendritic segment from a neuron co-transfected with myc-tagged-mock plasmid (blue) plus GFP-PSD95 (green) and stained for synaptophysin (red). (G) Merge image; note that GFP-PSD95 (+) spines colocalize with synaptophysin puncta (arrowheads). (H) A Confocal image showing an example of a 17 DIV cultured hippocampal neuron transfected with myc-tagged IQGAP1 WT+GFP (green) and double stained with MAP2 (red). (I) A high magnification view of a dendritic segment from another neuron of the same culture. (J) A 3-D reconstruction of dendritic shafts from a sister culture; note the increase in the number and size of spines. (K–N) Confocal images showing a segment of a dendritic shaft of a neuron co-transfected with myc-tagged-IQGAP1 WT (blue) plus GFP-PSD95 (green) and stained for synaptophysin (red). (N) Merge image. (O–Q) Graphs showing effects of ectopic expression of myc-tagged IQGAP1 WT on spine number, spine type and spine head size. Bars represent mean ± standard deviation. *p<0.0001. The effect of IQGAP1 mutants on spine number is also shown (O).