The Journal of Neuroscience, February 15, 2002, 22(4):1338-1349
Eph Receptor Tyrosine Kinase-Mediated Formation of a Topographic
Map in the Drosophila Visual System
Richard
Dearborn Jr1,
Qi
He2,
Sam
Kunes1, and
Yong
Dai1
1 Department of Molecular and Cellular Biology, Harvard
University, Cambridge, Massachusetts 02138, and
2 Department of Biology, City University of New York,
Brooklyn, New York 11210
Roles for Eph receptor tyrosine kinase signaling in the formation
of topographic patterns of axonal connectivity have been well
established in vertebrate visual systems. Here we describe a role for a
Drosophila Eph receptor tyrosine kinase (EPH) in the
control of photoreceptor axon and cortical axon topography in the
developing visual system. Although uniform across the developing eye,
EPH is expressed in a concentration gradient appropriate for conveying
positional information during cortical axon guidance in the
second-order optic ganglion, the medulla. Disruption of this graded
pattern of EPH activity by double-stranded RNA interference or by
ectopic expression of wild-type or dominant-negative transgenes perturbed the establishment of medulla cortical axon topography. In
addition, abnormal midline fasciculation of photoreceptor axons resulted from the eye-specific expression of the dominant-negative EPH
transgene. These observations reveal a conserved role for Eph kinases
as determinants of topographic map formation in vertebrates and invertebrates.
Key words:
Eph receptor; topographic map; visual system; axon
guidance; Drosophila visual system; optic lobe
Copyright © 2002 Society for Neuroscience 0270-6474/02/2241338-12$05.00/0
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