Coordinate control of terminal dendrite patterning and dynamics by the membrane protein Raw

Abstract

The directional flow of information in neurons depends on compartmentalization: dendrites receive inputs whereas axons transmit them. Axons and dendrites likewise contain structurally and functionally distinct subcompartments. Axon/dendrite compartmentalization can be attributed to neuronal polarization, but the developmental origin of subcompartments in axons and dendrites is less well understood. To identify the developmental bases for compartment-specific patterning in dendrites, we screened for mutations that affect discrete dendritic domains in Drosophila sensory neurons. From this screen, we identified mutations that affected distinct aspects of terminal dendrite development with little or no effect on major dendrite patterning. Mutation of one gene, raw, affected multiple aspects of terminal dendrite patterning, suggesting that Raw might coordinate multiple signaling pathways to shape terminal dendrite growth. Consistent with this notion, Raw localizes to branch-points and promotes dendrite stabilization together with the Tricornered (Trc) kinase via effects on cell adhesion. Raw independently influences terminal dendrite elongation through a mechanism that involves modulation of the cytoskeleton, and this pathway is likely to involve the RNA-binding protein Argonaute 1 (AGO1), as raw and AGO1 genetically interact to promote terminal dendrite growth but not adhesion. Thus, Raw defines a potential point of convergence in distinct pathways shaping terminal dendrite patterning.

Regulation of dendrite growth and maintenance by exocytosis

“…Primary and terminal dendrites of C4da neurons differ in their cytoskeletal composition and dynamics (Grueber et al, 2002;Jinushi-Nakao et al, 2007;Lee et al, 2015), which can create differences in membrane tension (Dai and Sheetz, 1999). As membrane tends to flow from a region of low tension to a region of higher tension (Dai and Sheetz, 1995), the resulting tension gradient could then explain how membrane proteins readily diffuse from major branches into terminals, but not in the opposite direction.…”

The SLC36 transporter Pathetic is required for extreme dendrite growth in Drosophila sensory neurons

“…EMS mutagenesis was conducted as previously described (Lee et al 2015). Transgenic lines were generated using P-element-mediated integration, except for UAS-Luciferase reporter lines, which were generated using φC31-mediated integration.…”

Epidermis-Derived Semaphorin Promotes Dendrite Self-Avoidance by Regulating Dendrite-Substrate Adhesion in Drosophila Sensory Neurons

“…To assess whether the Sema-2b/PlexB signaling pathway influences Trc kinase activity in vivo , we used a previously generated antibody that specifically detects phosphorylation on threonine residue 449 (T449) of Trc kinase, which is associated with maximal Trc kinase activation (Tamaskovic et al, 2003; Lee at al., 2014). In the larval body wall, Trc P-T449 immunoreactivity was present at high levels in the axons, dendrites and cell bodies of class IV da neurons (Figures 6A and 6D).…”