Semaphorins are a large family of molecules that repulse growth cones, but in some cases also attract them. The analyses of semaphorins and their neuropilin/plexin receptors have made important advances in our understanding of how growth cones are guided to their targets. However, our understanding of the function of semaphorins is still incomplete. First, the functional analysis of vertebrate semaphorins has been mostly of the secreted, Class 3 semaphorins. Our understanding of the function of the large transmembrane, Class 4 semaphorins is limited to Sema4D/CD100which plays a vital role in the immune system, but no nervous system function is known for any Class 4 semaphorin. This application will examine how Sema4E, a novel Class 4 semaphorin recently cloned by our lab, guides growth cones in the zebrafish embryo. Second, most vertebrate semaphorins that affect neurons exhibit a repulsive effect on axons, although in certain circumstances semaphorins can attract growth cones in vitro. Nevertheless, there are no examples of attractive actions on axons by a vertebrate semaphorin in vivo. This application will examine whether Sema3D, whose function is unknown in any organism, attracts and/or induces branching by axons in vivo in zebrafish embryos. The accessibility, manipulability, and transparency of the embryo have led to high resolution, cellular analyses of how specific growth cones find their targets in zebrafish. Furthermore, our laboratory has generated transgenic zebrafish in which several semaphorins can be induced, shown that transgenes can be activated in individual cells by focusing a laser microbeam onto cells, """"""""knocked down"""""""" semaphorins by injection of morpholino antisense oligos and applied dominant negative strategies. Preliminary evidence suggests that Sema4E and Sema3Al may restrict branchiomotor axons to their normal pathway, while Sema3D may attract or induce branching within the pharyngeal arch targets of these axons. This application will use these transgenic lines and generate new ones in order to assay both gain- and loss-of-function phenotypes for Sema4E, Sema3Al, and Sema3D to clarify their roles for guidance of the branchiomotor growth cones to and within the pharyngeal arches that they innervate.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Molecular, Cellular and Developmental Neurosciences 2 (MDCN)
Program Officer
Mamounas, Laura
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Michigan Ann Arbor
Schools of Arts and Sciences
Ann Arbor
United States
Zip Code
Saint-Amant, Louis; Sprague, Shawn M; Hirata, Hiromi et al. (2008) The zebrafish ennui behavioral mutation disrupts acetylcholine receptor localization and motor axon stability. Dev Neurobiol 68:45-61
Sato-Maeda, Mika; Tawarayama, Hiroshi; Obinata, Masuo et al. (2006) Sema3a1 guides spinal motor axons in a cell- and stage-specific manner in zebrafish. Development 133:937-47
Cui, Wilson W; Low, Sean E; Hirata, Hiromi et al. (2005) The zebrafish shocked gene encodes a glycine transporter and is essential for the function of early neural circuits in the CNS. J Neurosci 25:6610-20
Li, Qin; Shirabe, Komei; Thisse, Christine et al. (2005) Chemokine signaling guides axons within the retina in zebrafish. J Neurosci 25:1711-7
Li, Qin; Shirabe, Komei; Kuwada, John Y (2004) Chemokine signaling regulates sensory cell migration in zebrafish. Dev Biol 269:123-36
Liu, Yan; Berndt, Jason; Su, Fengyun et al. (2004) Semaphorin3D guides retinal axons along the dorsoventral axis of the tectum. J Neurosci 24:310-8
Xiao, Tong; Shoji, Wataru; Zhou, Weibin et al. (2003) Transmembrane sema4E guides branchiomotor axons to their targets in zebrafish. J Neurosci 23:4190-8
Shoji, Wataru; Isogai, Sumio; Sato-Maeda, Mika et al. (2003) Semaphorin3a1 regulates angioblast migration and vascular development in zebrafish embryos. Development 130:3227-36
Scheer, Nico; Riedl, Iris; Warren, J T et al. (2002) A quantitative analysis of the kinetics of Gal4 activator and effector gene expression in the zebrafish. Mech Dev 112:9-14
Blechinger, Scott R; Evans, Tyler G; Tang, Ping Tao et al. (2002) The heat-inducible zebrafish hsp70 gene is expressed during normal lens development under non-stress conditions. Mech Dev 112:213-5

Showing the most recent 10 out of 13 publications