Fig. 4.
Physiological roles for Abl-family kinases. (A) Abl is required for proper F-actin assembly during immune-synapse formation. Wild-type (WT, top) or Abl–/– (bottom) T cells were incubated with latex beads (right panels) coated with anti-T-cell-receptor antibody, and were then stained with phalloidin to reveal the F-actin cytoskeleton (left panels). Wild-type T cells form an immune-synapse-like concentration of F-actin at the bead contact site. The F-actin cytoskeleton remains diffusely localized in Abl–/– T cells. Figure courtesy of Ann Huang and Janis Burkhardt (University of Pennsylvania, Philadelphia, PA). (B) dAbl is required for proper axon guidance. In abdominal segments of wild-type (WT, left) Drosophila embryos, intersegmental neuron group b (ISNb) axons make normal neuromuscular junctions with longitudinal muscles, including muscle 12 (arrows). ISNb growth cones stop short and fail to contact muscle 12 in an Abl mutant (right). Adapted with permission from figure 3 in Wills et al. (Wills et al., 1999b). Figure courtesy of David Van Vactor (Harvard Medical School, Boston, MA). (C) Abl and Arg are required for dendrite stabilization. Camera lucida representations of wild-type (WT, top) or Abl–/– Arg–/– (bottom) cortical-layer-5 pyramidal neurons. Atrophy of dendrite arbors in Abl–/– Arg–/– neurons results in smaller dendrite arbors. (D) dAbl is essential for normal epithelial morphogenesis. Wild-type Drosophila embryos (WT, left) exhibit uniform apical constriction at the ventral furrow during gastrulation (arrow). Cell morphology is visualized using a moesin-GFP that binds to F-actin. An Ablmz mutant depleted for both maternal and zygotic Abl (right) exhibits non-uniform constriction. Figure courtesy of Don Fox and Mark Peifer (University of North Carolina, Chapel Hill, NC).