Rspo1 and Rspo3 are required for sensory lineage neural crest formation in mouse embryos

Area of Science:

• Developmental biology
• Molecular biology
• Neuroscience

Background:

• R-spondins (Rspos) are secreted proteins that regulate Wnt/β-catenin signaling.
• Wnt1, Wnt3a, Rspo1, and Rspo3 are co-expressed in the spinal cord roof plate during early development.
• This co-expression suggests a role for Rspos in dorsal spinal cord and neural crest cell development alongside Wnt ligands.

Purpose of the Study:

• To investigate the specific roles of Rspo1 and Rspo3 in spinal cord development.
• To determine the necessity of Rspo1 and Rspo3 for Wnt/β-catenin signaling in the developing spinal cord.
• To elucidate the contribution of Rspos to neural crest cell specification.

Main Methods:

• Generation of Rspo1 and Rspo3 double-knock-out (dKO) mouse embryos.
• Analysis of spinal cord development, including patterning, cell proliferation, and roof plate morphology.
• Assessment of Wnt/β-catenin signaling pathway activity.
• Evaluation of neural crest cell development, specifically Ngn2-positive cells.

Main Results:

• Rspo1 and Rspo3 maintained roof-plate-specific expression until late embryonic stages.
• Rspo-dKO embryos showed partially overlapping phenotypes with Wnt1 and Wnt3a dKO embryos.
• A reduction in Ngn2-positive sensory lineage neural crest cells was observed in Rspo-dKO embryos, while other dorsal spinal cord developmental aspects proceeded normally.
• Wnt/β-catenin signaling was not significantly altered in the developing spinal cord of Rspo-dKO embryos.

Conclusions:

• Rspo1 and Rspo3 are dispensable for most developmental processes mediated by roof plate-derived Wnt ligands.
• Rspos play a specific role in the specification of a particular neural crest cell subtype.
• R-spondin modulation of Wnt/β-catenin signaling appears to be context-dependent.