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Published October 2014 | public
Journal Article

Embryological manipulations in the developing Xenopus inner ear reveal an intrinsic role for Wnt signaling in dorsal–ventral patterning

Abstract

Background: The inner ear develops from an ectodermal thickening known as the otic placode into a complex structure that is asymmetrical along both the anterior–posterior (A-P) and dorsal–ventral (D-V) axes. Embryological manipulations in Xenopus allow us to test regenerative potential along specific axes and timing of axis determination. We explore the role of Wnt signaling with gain and loss of function experiments. Results: In contrast to A or P half ablations, D or V half ablations almost never result in mirror duplications or normal ears. Instead there is a loss of structures, especially those associated with the ablated region. Rotation experiments inverting the D-V axis reveal that it is determined by stage 24–26 which is just before expression of the dorsal otic marker Wnt3a. Conditional blocking of canonical Wnt signaling results in reductions in the number of sensory organs and semicircular canals which could be placed in one of three categories, the most common phenotypes being similar to those seen after dorsal ablations. Conclusions: There is less regenerative potential along the D-V axis. Wnt3a protein alone is sufficient to rescue the severe loss of inner ear structures resulting from dorsal but not ventral half ablations.

Additional Information

© 2014 Wiley Periodicals, Inc. Submitted 11 May 2013; First Decision 2 January 2014; Accepted 17 January 2014; Published online 5 February 2014. This work was supported by RO1 Grant DC004061 to A. Collazo from the National Institutes of Health (NIH) and National Institute for Deafness and Other Communication Disorders (NIDCD) and by a National Organization for Hearing Research (NOHR) grant to C. Forristall. This work was also supported by the Oberkotter Foundation through the House Ear Institute/House Research Institute, where much of this work was done. We want to thank the many University of Redlands students who worked on this project. Specifically we acknowledge the work of John Gregorius, Darlynn Korns, Kristen Block, and Gerald Chavez. We also thank the members of the Andy K. Groves, Neil Segil, and Andres Collazo laboratories when they were at the House Ear Institute, for their stimulating discussions of the data presented here. Core resources were provided by the Ahmanson Foundation and NIH to D.J.L. The Xenopus Wnt3a probe was kindly provided by Dr. Randy Moon.

Additional details

Created:
August 22, 2023
Modified:
October 18, 2023