The Drosophila Wnt5 protein mediates selective axon fasciculation in the embryonic central nervous system.

Abstract

The decision of whether and where to cross the midline, an evolutionarily conserved line of bilateral symmetry in the central nervous system, is the first task for many newly extending axons. We show that Wnt5, a member of the conserved Wnt secreted glycoprotein family, is required for the formation of the anterior of the two midline-crossing commissures present in each Drosophila hemisegment. Initial path finding of pioneering neurons across the midline in both commissures is normal in wnt5 mutant embryos; however, the subsequent separation of the early midline-crossing axons into two distinct commissures does not occur. The majority of the follower axons that normally cross the midline in the anterior commissure fail to do so, remaining tightly associated near their cell bodies, or projecting inappropriately across the midline in between the commissures. The lateral and intermediate longitudinal pathways also fail to form correctly, similarly reflecting earlier failures in pathway defasciculation. Panneural expression of Wnt5 in a wnt5 mutant background rescues both the commissural and longitudinal defects. We show that the Wnt5 protein is predominantly present on posterior commissural axons and at a low level on the anterior commissure and longitudinal projections. Finally, we demonstrate that transcriptional repression of wnt5 in AC neurons by the recently described Wnt5 receptor, Derailed, contributes to this largely posterior commissural localization of Wnt5 protein.

• Authors: Lee G Fradkin, Martijn van Schie, Rene R Wouda, Anja de Jong, Jessica T Kamphorst, Monique Radjkoemar-Bansraj, Jasprina N Noordermeer
• Journal: Developmental biology (Dev Biol) Vol. 272 Issue 2 Pg. 362-75 (Aug 15 2004) ISSN: 0012-1606 [Print] United States
• PMID: 15282154 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Drosophila Proteins
• Egg Proteins
• Membrane Proteins
• Proto-Oncogene Proteins
• RNA, Messenger
• Wnt Proteins
• Wnt5 protein, Drosophila
• por protein, Drosophila
• DRL protein, Drosophila
• Receptor Protein-Tyrosine Kinases

Topics

• Animals
• Animals, Genetically Modified
• Axons (physiology)
• Central Nervous System (embryology)
• Drosophila (embryology)
• Drosophila Proteins (genetics, metabolism)
• Egg Proteins (genetics, metabolism)
• Embryo, Nonmammalian
• Fasciculation (genetics)
• Gene Expression Regulation, Developmental
• Membrane Proteins (genetics, metabolism)
• Mutation
• Neurons (metabolism)
• Proto-Oncogene Proteins (genetics, metabolism)
• RNA, Messenger (metabolism)
• Receptor Protein-Tyrosine Kinases (genetics, metabolism)
• Wnt Proteins