BDNF in the Development of the Visual System of Xenopus
To explore the role of BDNF during Xenopus visual system development, the expression of BDNF and TrkB, as well as the effect of BDNF during retinal ganglion cell (RGC) development in culture, was examined. BDNF mRNA was found to be expressed in both the developing eye and tectum, peaking at stage 45/46. The expression of BDNF coincided with RGC expression of full-length trkB transcripts, suggesting a functional role for BDNF. In culture, BDNF significantly increased the number of RGCs. The ability of BDNF to rescue differentiated RGCs that had projected to the tectum, the time course of the effect, and the lack of mitogenic response indicate that this neurotrophin promotes survival. The expression of BDNF and TrkB and the responsiveness of RGCs to BDNF coincide with retinal axon terminal arborization and patterning. Our results indicate that BDNF is a relevant neurotrophin for Xenopus RGC development and suggest that it plays a role during visual system patterning.
© 1994 Cell Press. Received 14 April 1993, Revised 26 January 1994. We thank Genentech Inc. for providing the trophic factors used in this work and Drs. E. Escandón and K. Nikolics for performing preliminary BDNF cross-linking studies. We also thank Dr. P. Isackson for providing the Xenopus BDNF cDNA clone, Dr. P. Tsoulfas for the design of PCR primers, and Drs. P. Tsoulfas and F. Kayyem for advise with PCR amplification. We are also grateful to Ors. A. Collazo, G. Serbedzija, and B. Trevarrow for helpful comments on the manuscript and Dr. J. Shih for contributions to several aspects of this work. This work was supported by the Muscular Dystrophy Association, the Helen Hay Whitney Foundation, and NIMH grant MH49176. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 USC Section 1734 solely to indicate this fact.