Endothelial and fibroblast cell-derived heparan sulphate bind with differing affinity to basic fibroblast growth...

Area of Science:

• Biochemistry
• Cell Biology
• Glycobiology

Background:

• Heparan sulphate (HS) plays a crucial role in regulating protein-ligand interactions, including the binding of fibroblast growth factor 2 (FGF2).
• Endothelial cell-derived HS (ECHS) exhibits lower affinity for FGF2 compared to fibroblast-derived HS (FHS).
• Understanding the structural basis for these affinity differences is critical for elucidating HS function in biological processes.

Purpose of the Study:

• To investigate the structural determinants responsible for the differential binding affinities of ECHS and FHS to FGF2.
• To identify specific structural features within HS chains that contribute to FGF2 binding affinity.

Main Methods:

• Enzymatic degradation of intact ECHS and FHS chains using heparinase III.
• Filter binding assays to quantify the binding affinity of HS fragments and intact chains to FGF2.
• Disaccharide compositional analysis of HS oligosaccharides to determine sulphation patterns.

Main Results:

• Heparinase III-resistant fragments of ECHS, 6-7 disaccharides in length, showed FGF2 binding affinity similar to intact ECHS.
• The largest heparinase III-resistant fragments from FHS also exhibited reduced FGF2 binding affinity compared to intact FHS.
• Disaccharide analysis revealed similar sulphation patterns in both ECHS and FHS oligosaccharides, indicating sulphation alone does not explain affinity differences.

Conclusions:

• Neither the sulphation pattern nor the overall length of HS chains are the sole factors governing FGF2 binding affinity.
• The domain organization and frequency of large heparinase III-resistant oligosaccharides within intact HS chains are critical for determining binding affinity.
• These structural features likely regulate other biological functions of HS beyond FGF2 binding.