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Structural insights into the formation of repulsive netrin guidance complexes
Jessica M Priest1,2,3, Ev L Nichols4,5, Robert G Smock6
1Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA.
Science Advances
|February 16, 2024
Summary
Heparin binding to Uncoordinated-5 (UNC-5) receptor is crucial for repulsive netrin signaling. This interaction forms a complex that guides cell migration and axon growth, essential for proper development.
Area of Science:
- Molecular and Cellular Biology
- Developmental Biology
- Neuroscience
Background:
- Netrins are guidance cues regulating cell migration and axon growth.
- The Uncoordinated-5 (UNC-5) receptor mediates repulsive responses to netrins.
- The role of heparin in UNC-5-mediated repulsion was previously unclear.
Purpose of the Study:
- To investigate the structural and functional role of heparin in UNC-5-mediated netrin repulsion.
- To elucidate the mechanism by which heparin modulates UNC-5 and UNC-6/netrin interactions.
- To determine the in vivo significance of UNC-5 heparin-binding in Caenorhabditis elegans development.
Main Methods:
- Structural determination of UNC-5 bound to a heparin fragment.
- Directed evolution and structure-based rational design to modulate UNC-5-heparin affinity.
- Biochemical assays to analyze complex formation and receptor binding.
- Genetic analysis in Caenorhabditis elegans using UNC-5 mutants.
Main Results:
- UNC-5 is a heparin-binding protein, and its structure bound to heparin was determined.
- Heparin binding stabilizes a large, rigid complex of UNC-5 and UNC-6/netrin.
- Heparin and UNC-5 binding to UNC-6/netrin exclude the attractive receptor UNC-40/DCC.
- Loss of UNC-5 heparin-binding in C. elegans abrogates cell migration and gonad development.
Conclusions:
- Heparin is a critical regulator of repulsive netrin signaling by forming a stable macromolecular complex with UNC-5 and UNC-6/netrin.
- This glycosaminoglycan-regulated complex is essential for proper cell migration and axon guidance.
- The findings reveal a novel mechanism for controlling directional cell movement during development.
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