Neuroscience 2005 Abstract
| Presentation Number: | 600.10 |
|---|---|
| Abstract Title: | The function of Slit and Robo in <i>Xenopus</i> retinal ganglion cell dendrite development. |
| Authors: |
Hocking, J. C.*1
; Wu, J.2
; McFarlane, S.1
1Hotchkiss Brain Inst., Univ. of Calgary, Calgary, Canada 2TN, 3330 Hospital Dr NW, T2N 4N1, |
| Primary Theme and Topics |
Development - Axonal and Dendritic Development -- Dendritic growth and branching |
| Session: |
600. Dendrite Growth and Branching II Poster |
| Presentation Time: | Tuesday, November 15, 2005 9:00 AM-10:00 AM |
| Location: | Washington Convention Center - Hall A-C, Board # C21 |
| Keywords: | EYE, GUIDANCE, VISION, NEURITE OUTGROWTH |
We previously found Xenopus slit mRNA in the amacrine cells of the developing retina, at the appropriate stages to influence retinal ganglion cell (RGC) dendrite outgrowth and branching (Hocking et al., 2004 SFN abstract). Here, we examined the mRNA expression of the Slit receptors, robo1, robo2 and robo3 in the Xenopus retina by in situ hybridization. Xenopus robo1 (cDNA obtained from Dr. B. Key) showed no expression in the retina. Fragments of the Xenopus laevis robo2 gene were amplified by PCR using primers based on the robo2 sequence in the Xenopus tropicalis genome assembly. Expression of robo3 was examined using two EST sequences obtained from the IMAGE consortium. Starting at stage 32, robo2 is strongly, and robo3 weakly, expressed in RGCs. Since RGCs express Robo receptors, and an adjacent cell population expresses the ligand Slit, we hypothesized that Slit signaling enhances outgrowth of RGC dendritic arbors. To test this, we expressed a rat dominant negative Robo1 (dnRobo1) (Stein and Tessier-Lavigne, 2001) in developing RGCs, with the expectation that it would interfere with the endogenous Robo2 and Robo3 function. CS2-dnRobo1 was injected into blastomeres at the four to eight cell stage, and CS2-GFP was injected into sister embryos to act as a control. The dnRobo1 significantly reduced the arbor size from an average extent of 10.6 +/-0.3 μm across to 7.2+/-1.1 μm, (p<0.05). Also, 53.9+/-4.2% of the cells expressing dnRobo1 had zero or one primary dendrite, compared to 41.2+/-2.2% of the GFP-expressing RGCs. Finally, branching was also inhibited, such that 73.0+/-12.6% of the dnRobo1-expressing RGCs with dendrites had little or no branching, compared to 31.6 +/-2.7% of the GFP-expressing RGCs (p<0.05). In conclusion, our data support that Slit expressed in amacrine cells signals to RGCs through the Robo receptor to enhance dendritic outgrowth and branching.
Supported by AHFMR, NSERC, CIHR
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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