Abstract
BackgroundProper dendrite patterning is critical for the receiving and processing of information in the nervous system. Cell-autonomous molecules have been extensively studied in dendrite morphogenesis; however, the regulatory mechanisms of environmental factors in dendrite growth remain to be elucidated.ResultsBy evaluating the angle between two primary dendrites (PD-Angle), we found that the directional growth of the primary dendrites of a Drosophila periphery sensory neuron ddaE is regulated by the morphogen molecule Wingless (Wg). During the early stage of dendrite growth, Wg is expressed in a group of epithelial cells posteriorly adjacent to ddaE. When Wg expression is reduced or shifted anteriorly, the PD-Angle is markedly decreased. Furthermore, Wg receptor Frizzled functions together with Flamingo and Dishevelled in transducing the Wg signal into ddaE neuron, and the downstream signal is mediated by non-canonical Wnt pathway through Rac1.ConclusionsIn conclusion, we reveal that epithelia-derived Wg plays a repulsive role in regulating the directional growth of dendrites through the non-canonical Wnt pathway. Thus, our findings provide strong in vivo evidence on how environmental signals serve as spatial cues for dendrite patterning.Electronic supplementary materialThe online version of this article (doi:10.1186/s13041-016-0228-0) contains supplementary material, which is available to authorized users.
Highlights
Proper dendrite patterning is critical for the receiving and processing of information in the nervous system
The PD-Angle of the ddaE neuron is decreased when Wg expression is reduced in the adjacent epithelial cells To study whether the primary dendrites of the ddaE neuron develop according to the environmental signals, we examined the localization of epithelia-derived signals relative to the ddaE neuron at the early dendritogenesis stage, i.e. embryonic stage 13–14
Using wg-Gal4;UASmGFP embryos, we found that in the dorsal region of the abdominal segments 4–6 (AS4-6), Wg was expressed in a small group of epithelial cells adjacent to the dorsal cluster of da neurons (Fig. 1a); as shown in the X-Z or YZ section images, Wg expression was not detected in those neurons (Fig. 1a’)
Summary
Proper dendrite patterning is critical for the receiving and processing of information in the nervous system. Dendrites receive and process most of the information from external stimuli and input neurons; it is essential for dendrites to develop an elaborate arborization pattern Both cell-intrinsic and extrinsic factors play instructive roles in regulating dendrite development [1]. It has been reported that extrinsic factors originating from the ECM and epithelium adjacent to da neurons regulate the tiling, scaling and self-avoidance processes of class IV da neurons [12,13,14,15,16] These factors play essential roles in establishing and maintaining the radial dendrite pattern of class IV neurons, ensuring that the neurons cover the whole body wall of larvae. Whether its directional growth is regulated by environmental cues remains uninvestigated
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