Commissural axons switch on responsiveness to Wnt attraction during midline crossing to turn anteriorly after exiting the floor plate. We report here Sonic Hedgehog (Shh) downregulates Shisa2, which inhibits glycosylation and cell surface presentation of Frizzled3 in rodent commissural axon growth cones. Constitutive Shisa2 expression causes randomized turning of post-crossing commissural axons along the anterior-posterior (A-P) axis. Loss of Shisa2 lead to precocious anterior turning of commissural axons before or during midline crossing. Post-crossing commissural axon turning is completely randomized along the A-P axis when Wntless, essential for Wnt secretion, is conditionally knocked out in the floor plate. The regulatory link between Shh and PCP signaling may also occur in other developmental processes.
- Yimin Zou
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: Experiments were conducted in accordance with the NIH Guide for the Care and Use of LaboratoryAnimals and approved by the UCSD Animal Subjects Committee (Approved Protocol #: S06219, S06222).
- Carol A Mason, Columbia University, United States
© 2017, Onishi & Zou
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