Wnt/Calcium Signaling Mediates Axon Growth and Guidance in the Developing Corpus Callosum

It has been shown in vivo that Wnt5a gradients surround the corpus callosum and guide callosal axons after the midline (postcrossing) by Wnt5a-induced repulsion via Ryk receptors. In dissociated cortical cultures we showed that Wnt5a simultaneously promotes axon outgrowth and repulsion by calcium si...

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Main Authors:	Hutchins, B Ian, Li, Li, Kalil, Katherine
Format:	Online
Language:	English
Published:	Wiley Subscription Services, Inc., A Wiley Company 2011
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3099647/

id	pubmed-3099647
recordtype	oai_dc
spelling	pubmed-30996472011-07-07 Wnt/Calcium Signaling Mediates Axon Growth and Guidance in the Developing Corpus Callosum Hutchins, B Ian Li, Li Kalil, Katherine Research Article It has been shown in vivo that Wnt5a gradients surround the corpus callosum and guide callosal axons after the midline (postcrossing) by Wnt5a-induced repulsion via Ryk receptors. In dissociated cortical cultures we showed that Wnt5a simultaneously promotes axon outgrowth and repulsion by calcium signaling. Here to test the role of Wnt5a/calcium signaling in a complex in vivo environment we used sensorimotor cortical slices containing the developing corpus callosum. Plasmids encoding the cytoplasmic marker DsRed and the genetically encoded calcium indicator GCaMP2 were electroporated into one cortical hemisphere. Postcrossing callosal axons grew 50% faster than pre-crossing axons and higher frequencies of calcium transients in axons and growth cones correlated well with outgrowth. Application of pharmacological inhibitors to the slices showed that signaling pathways involving calcium release through IP3 receptors and calcium entry through TRP channels regulate post-crossing axon outgrowth and guidance. Co-electroporation of Ryk siRNA and DsRed revealed that knock down of the Ryk receptor reduced outgrowth rates of postcrossing but not precrossing axons by 50% and caused axon misrouting. Guidance errors in axons with Ryk knockdown resulted from reduced calcium activity. In the corpus callosum CaMKII inhibition reduced the outgrowth rate of postcrossing (but not precrossing) axons and caused severe guidance errors which resulted from reduced CaMKII-dependent repulsion downstream of Wnt/calcium. We show for the first time that Wnt/Ryk calcium signaling mechanisms regulating axon outgrowth and repulsion in cortical cultures are also essential for the proper growth and guidance of postcrossing callosal axons which involve axon repulsion through CaMKII. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 71: 269–283, 2011. Wiley Subscription Services, Inc., A Wiley Company 2011-04 2010-10-08 /pmc/articles/PMC3099647/ /pubmed/20936661 http://dx.doi.org/10.1002/dneu.20846 Text en Copyright © 2011 Wiley Periodicals, Inc., A Wiley Company http://creativecommons.org/licenses/by/2.5/ Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.5, which does not permit commercial exploitation.
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Hutchins, B Ian Li, Li Kalil, Katherine
spellingShingle	Hutchins, B Ian Li, Li Kalil, Katherine Wnt/Calcium Signaling Mediates Axon Growth and Guidance in the Developing Corpus Callosum
author_facet	Hutchins, B Ian Li, Li Kalil, Katherine
author_sort	Hutchins, B Ian
title	Wnt/Calcium Signaling Mediates Axon Growth and Guidance in the Developing Corpus Callosum
title_short	Wnt/Calcium Signaling Mediates Axon Growth and Guidance in the Developing Corpus Callosum
title_full	Wnt/Calcium Signaling Mediates Axon Growth and Guidance in the Developing Corpus Callosum
title_fullStr	Wnt/Calcium Signaling Mediates Axon Growth and Guidance in the Developing Corpus Callosum
title_full_unstemmed	Wnt/Calcium Signaling Mediates Axon Growth and Guidance in the Developing Corpus Callosum
title_sort	wnt/calcium signaling mediates axon growth and guidance in the developing corpus callosum
description	It has been shown in vivo that Wnt5a gradients surround the corpus callosum and guide callosal axons after the midline (postcrossing) by Wnt5a-induced repulsion via Ryk receptors. In dissociated cortical cultures we showed that Wnt5a simultaneously promotes axon outgrowth and repulsion by calcium signaling. Here to test the role of Wnt5a/calcium signaling in a complex in vivo environment we used sensorimotor cortical slices containing the developing corpus callosum. Plasmids encoding the cytoplasmic marker DsRed and the genetically encoded calcium indicator GCaMP2 were electroporated into one cortical hemisphere. Postcrossing callosal axons grew 50% faster than pre-crossing axons and higher frequencies of calcium transients in axons and growth cones correlated well with outgrowth. Application of pharmacological inhibitors to the slices showed that signaling pathways involving calcium release through IP3 receptors and calcium entry through TRP channels regulate post-crossing axon outgrowth and guidance. Co-electroporation of Ryk siRNA and DsRed revealed that knock down of the Ryk receptor reduced outgrowth rates of postcrossing but not precrossing axons by 50% and caused axon misrouting. Guidance errors in axons with Ryk knockdown resulted from reduced calcium activity. In the corpus callosum CaMKII inhibition reduced the outgrowth rate of postcrossing (but not precrossing) axons and caused severe guidance errors which resulted from reduced CaMKII-dependent repulsion downstream of Wnt/calcium. We show for the first time that Wnt/Ryk calcium signaling mechanisms regulating axon outgrowth and repulsion in cortical cultures are also essential for the proper growth and guidance of postcrossing callosal axons which involve axon repulsion through CaMKII. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 71: 269–283, 2011.
publisher	Wiley Subscription Services, Inc., A Wiley Company
publishDate	2011
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3099647/
_version_	1611455081924788224

Wnt/Calcium Signaling Mediates Axon Growth and Guidance in the Developing Corpus Callosum

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