N-syndecan (syndecan 3) from neonatal rat brain binds basic fibroblast growth factor

Area of Science:

• Neuroscience
• Biochemistry
• Molecular Biology

Background:

• N-syndecan (syndecan 3) is a cell surface proteoglycan found in neonatal rat brain.
• Its biochemical properties, including heparan sulfate glycosaminoglycan chains and a 120 kDa core protein, are similar to N-syndecan from Schwann cells.

Purpose of the Study:

• To investigate the interactions between purified N-syndecan and various extracellular ligands.
• To identify specific binding partners of N-syndecan in the context of nerve tissue development.

Main Methods:

• Isolation of N-syndecan from neonatal rat brain.
• Solid-phase binding assays to test interactions with growth factors and extracellular matrix molecules.
• Competition assays using soluble and immobilized ligands, and inhibition studies with glycosaminoglycans.

Main Results:

• N-syndecan specifically binds to basic fibroblast growth factor (bFGF) with high affinity (KD = 0.5 nM).
• Binding is mediated by the heparan sulfate chains of N-syndecan, not the core protein.
• Acidic FGF and other heparin-binding proteins did not bind to N-syndecan, indicating specific interaction with bFGF.

Conclusions:

• N-syndecan acts as a specific binding protein for bFGF in the neonatal brain.
• The heparan sulfate chains of N-syndecan are crucial for this interaction.
• N-syndecan may function as a co-receptor for bFGF, playing a role in nerve tissue development.