Extracellular interactions and ligand degradation shape the nodal morphogen gradient

Area of Science:

• Developmental Biology
• Cell Signaling
• Biophysics

Background:

• Morphogen gradients are essential for embryonic development.
• Nodal morphogens play a key role in embryonic axis formation.
• Existing models for Nodal gradient formation lack in vivo validation.

Purpose of the Study:

• To elucidate the in vivo mechanisms of Nodal morphogen gradient formation.
• To quantify Nodal ligand interactions and diffusion dynamics.
• To determine the contribution of ligand degradation to gradient shaping.

Main Methods:

• Fluorescence cross-correlation spectroscopy (FCCS) to measure binding affinities.
• Fluorescence correlation spectroscopy (FCS) to determine diffusion coefficients in live zebrafish embryos.
• Computational simulations to model gradient formation.

Main Results:

• Measured in vivo binding affinities of Nodal ligands to Acvr2b and Lefty.
• Quantified diffusion coefficients of Nodal ligands and Lefty inhibitors.
• Demonstrated that ligand degradation significantly shapes the Nodal gradient and its signaling range.

Conclusions:

• Ligand degradation is a critical factor in Nodal morphogen gradient formation.
• A combination of diffusivity, extracellular interactions, and selective ligand destruction shapes the Nodal gradient.
• Findings provide new insights into the biophysical mechanisms of developmental signaling.