Propeptide glycosylation and galectin-3 binding decrease proteolytic activation of human proMMP-9/progelatinase B.

Area of Science:

• Biochemistry
• Enzymology
• Glycobiology

Background:

• Matrix metalloproteinases (MMPs) are crucial enzymes involved in extracellular matrix remodeling.
• MMP-9 propeptide undergoes unique N-linked glycosylation, influencing its activation.
• ProMMP-9 activation is a stepwise process involving cleavage by other proteases.

Purpose of the Study:

• To investigate the role of MMP-9 propeptide glycosylation in its proteolytic activation.
• To identify new cleavage sites within the MMP-9 propeptide.
• To assess the impact of glycosylation on proMMP-9 resistance to various proteases and its activation rate.

Main Methods:

• Chemical synthesis of aglycosyl propeptides and purification of recombinant glycosylated propeptides.
• Western blot analysis to assess proteolysis resistance.
• Zymography and dye-quenched gelatin cleavage assays to evaluate proteolytic activation.
• Analysis of proMMP-9 from Congenital Disorder of Glycosylation patients.

Main Results:

• New cleavage sites in the MMP-9 propeptide by MMP-3 and neutrophil elastase were identified.
• Glycosylated pro-AT exhibited higher resistance to proteolysis compared to aglycosyl forms.
• Larger oligosaccharides on human neutrophil proMMP-9 increased resistance to activation.
• ProMMP-9 from CDG patients showed a higher activation rate by MMP-3.
• Glycan-galectin-3 interactions were found to reduce proMMP-9 activation.

Conclusions:

• MMP-9 propeptide glycosylation is a critical regulatory mechanism for its activation.
• Glycosylation influences proMMP-9 stability and susceptibility to proteolysis.
• This modification plays a significant role in modulating MMP-9 activity in physiological and pathological contexts.