Fig. 3

Abi acts downstream of Abl and Rac1 via SCAR complex activation. a–d Genetic interactions between abi and Abl regulating synaptic architecture. a Sample confocal images of anti-HRP-stained neuromuscular junction (NMJ) 6/7 in wild type, abi⁵/+, Abl⁴/+, and abi⁵,+/+,Abl⁴. b Quantification of total (top) and satellite (bottom) bouton number reveals a transheterozygous interaction between abi and Abl. c Sample confocal images of anti-HRP-stained NMJ 6/7 in Abl¹/Abl⁴, C155-GAL4/+, C155-GAL4/+; UAS-HA-abi^4YE, and C155-GAL4/+; Abl⁴,+/Abl¹,UAS-HA-abi^4YE. d Quantification of total (top) and satellite (bottom) bouton number reveals that Abl synaptic overgrowth is suppressed by neural overexpression of phospho-mimic Abi-4YE, while Abl-induced synaptic undergrowth is suppressed by decreasing abi gene dose. e–g Genetic interactions between abi and Rac1, SCAR and kette. e Sample confocal images of anti-HRP-stained NMJ 6/7 in Rac1^J11/+, SCAR^Δ37/+, kette^J4–48/+, abi⁵,+/+,Rac1^J11, SCAR^Δ37/+; abi⁵/+, and abi⁵,+/+,kette^J4–48. f Quantification of total (top) and satellite (bottom) bouton number reveals transheterozygous interactions of abi with Rac1, SCAR, and kette but not with WASp. g Quantification of total (top) and satellite (bottom) bouton number reveals that Rac1-G12V-induced overgrowth is suppressed by decreasing abi gene dose. Bar graphs indicate mean ± s.e.m. NMJ number analyzed for each genotype is indicated inside bars. Comparisons made against wild type (b, d, f) or C155-GAL4/+ (g) unless indicated (one-way analysis of variance with Tukey–Kramer post hoc test; *P < 0.001; **P < 0.01; ***P < 0.05; n.s. not significant). Insets (a, c, e) show higher magnification views of boutons marked by white asterisks. Satellite boutons are indicated by arrowheads. Scale bars: 20 μm