Neuroscience 2002 Abstract
| Presentation Number: | 27.17 |
|---|---|
| Abstract Title: | THE ROLE OF THROMBOSPONDIN IN AXON GUIDANCE: ONE MOLECULE, TWO FUNCTIONS? |
| Authors: |
Manning, T. J.*1
; Spitzer, N. C.1
1Department of Biology, University of California at San Diego, La Jolla, CA |
| Primary Theme and Topics |
Development - Axonal and Dendritic Development -- Axon growth and guidance: extracellular signals |
| Secondary Theme and Topics | Development<br />- Axonal and Dendritic Development<br />-- Axon growth and guidance: receptors and signaling mechanisms |
| Session: |
27. Axonal and dendritic development: axon growth and guidance--extracellular signals Poster |
| Presentation Time: | Sunday, November 3, 2002 8:00 AM-9:00 AM |
| Location: | Hall A2-B3 B-21 |
| Keywords: | development, xenopus, growth cone |
Thrombospondin (TSP) is a secreted glycoprotein that exists either in a soluble form or in a bound form associated with the extracellular matrix. This raises the hypothesis that each form exerts distinct effects on axon guidance. Immunostaining of whole mount Xenopus embryos reveals that TSP is associated with axon tracts in the spinal cord during early stages of neuronal development. Since TSP is localized to areas of axon outgrowth, we examined the effects of TSP on neurons developing in vitro. Neurons grown on TSP adsorbed to the culture dish have axons ~60% longer than those grown on tissue culture plastic, and exhibit a prominent increase in filopodia along their length. To assess the effects TSP on axon guidance, we monitored growth cone responses to both a gradient of TSP in solution and when encountering a substrate border of TSP adsorbed to the culture dish. Interestingly, growth cones displayed contrasting behaviors when encountering TSP in these different forms. A soluble gradient of TSP stimulates turning towards higher concentrations while growth cones approaching a substrate-associated border of TSP turn away without crossing. This result suggests that TSP may have different effects on axon outgrowth depending on the manner in which it is presented to the neuron. Fluctuations of intracellular Ca2+ are likely playing a role in TSP-mediated axon guidance. Removal of extracellular Ca2+ from the culture media or chelation of intracellular Ca2+ with Bapta-AM blocks growth cone turning in response to a soluble gradient of TSP. Our studies suggest that TSP plays a role in axon guidance, and exerts different effects depending on its presentation to the growth cone. Supported by NS15918.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2002 Neuroscience Meeting Planner. Orlando, FL: Society for Neuroscience, 2002. Online.
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