Spinal lumen remodeling under the control of Gli signaling mechanically drives roof plate cells extension

Abstract

Morphogenesis often requires different cell types to coordinate their behaviors for an harmonious developpement. How these different cell type behaviors are synchronized within and between tissues remains one of the important questions to fully understand morphogenesis. We used the zebrafish developing spinal cord to study this question. At later stages of neurogenesis, the lumen of the neural tube remodels, by reducing its height dramatically to form the persisting ventral central canal, a morphogenetic process conserved in vertebrates. By combining genetics, cell signaling manipulation with antagonist drugs and high-resolution in vivo live imaging, we better characterised the dynamics and control of this remodeling process. We showed that the lumen retraction depends on Gli activity regulation, a downstream effector of the Shh morphogen signal. We further established that the lumen retraction is instrumental in the cellular elongation of spinal roof plate cells, a population that forms the ceiling of the spinal cord lumen. Our work therefore establishes that the Gli transcriptional regulators under the control of long-range morphogen Shh control lumen retraction and that this retraction is a key driver of the roof plate cells extension.