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. 2005 Jun 29;25(26):6105–6118. doi: 10.1523/JNEUROSCI.1432-05.2005

Figure 6.

Figure 6.

Arg promotes axon and dendrite branching in cultured cortical neurons. A, Diagram of Arg and Arg mutants used in these assays. The Arg N-terminal half contains SH3 (3), SH2 (2), and kinase domains. The Arg C-terminal half contains two F-actin-binding domains (F) and a microtubule-binding domain (MT). ArgKI has a point mutation rendering it kinase inactive. ArgΔC lacks the cytoskeleton-binding domains. ArgΔSH3 has a deletion of the SH3 domain, rendering it hyperactive for kinase activity. B, Camera lucida drawings of cortical neurons transfected with vector alone or with expression vectors for Arg and ArgKI made at 4 DIV. C-E, Quantitation of branchpoint number, total length, and branchpoints/length for neurites (C), dendrites (D), and axons (E) in neurons expressing vector alone or expression vectors for Arg, ArgKI, ArgΔC, and ArgΔSH3. All values represent mean ± SE. C, Vector, n = 202 neurons, eight transfections; Arg, n = 197 neurons, eight transfections; ArgKI, n = 187 neurons, six transfections; ArgΔC, n = 93 neurons, six transfections; ArgΔSH3, n = 53 neurons, four transfections. D, E, Vector, n = 126 neurons, five transfections; Arg, n = 123 neurons, five transfections; ArgKI, n = 123 neurons, four transfections; ArgΔC, n = 81 neurons, four transfections; ArgΔSH3, n = 45 neurons, three transfections. For neurites, ANOVA between all transfection conditions is as follows: branchpoints, p < 0.0001; length, p = 0.035; branchpoints/length, p < 0.0001. For dendrites, ANOVA between all transfection conditions: branchpoints, p < 0.0001; dendrite length, p = 0.0023; branchpoints/length, p < 0.0001. For axons, ANOVA between all transfection conditions is as follows: branchpoints, p < 0.0001; axon length, p = 0.0002; branchpoints/length, p < 0.0001. Posthoc Student-Newman-Keuls test for each Arg construct versus vector alone: *p < 0.05. E, F, Cultured cortical neurons immunostained with α-Arg (E) or α-Abl (F) antibodies at 5 or 6 DIV. Phase-contrast images are shown in the right panels. Axons are indicated by white arrowheads. Boxed regions are enlarged below each image. Endogenous Arg is concentrated in growth cones and at phase-dense spots along neurites. Endogenous Abl is present more homogeneously throughout neurites, with a slight concentration in the growth cone. Scale bars, 40 μm.