Growth factor control of extracellular proteolysis

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Angiogenesis, the formation of new blood vessels, is a complex process involving growth factors and proteases.
• Basic fibroblast growth factor (bFGF) is a known angiogenic factor.
• Transforming growth factor beta (TGF-beta) acts as a negative regulator of angiogenesis.

Purpose of the Study:

• To elucidate the complex interplay between proteases and growth factors in regulating angiogenesis.
• To investigate the mechanisms by which bFGF and TGF-beta influence angiogenic processes.
• To understand the role of proteases in activating and modulating growth factor activity.

Main Methods:

• Investigated the effects of bFGF on endothelial cells.
• Analyzed the synthesis and cell surface expression of proteases (plasminogen activator, collagenase) and their receptors.
• Examined the activation of latent TGF-beta by protease systems.

Main Results:

• bFGF stimulation led to increased synthesis of plasminogen activator and collagenase in endothelial cells.
• bFGF upregulated plasminogen activator receptors on endothelial cells.
• Proteolytic activation of latent TGF-beta by plasminogen activator and plasmin was observed, forming a self-regulatory loop as TGF-beta induces plasminogen activator inhibitor.

Conclusions:

• Proteases play a critical role in both promoting angiogenesis (via bFGF) and regulating its inhibition (via TGF-beta).
• The release of active bFGF may involve plasmin-mediated cleavage of heparan sulfate complexes.
• A self-regulatory mechanism exists where TGF-beta's inhibitory action is modulated by protease activity, which it also influences.