Osteopontin is proteolytically processed by matrix metalloproteinase 9
Osteopontin is robustly upregulated following myocardial infarction (MI), which suggests that it has an important role in post-MI remodeling of the left ventricle (LV). Osteopontin deletion results in increased LV dilation and worsened cardiac function. Thus, osteopontin exerts protective
effects post-MI, but the mechanisms have yet to be defined. Matrix metalloproteinases (MMPs) regulate LV remodeling post-MI, and osteopontin is a known substrate for MMP-2, -3, -7, and -9, although the cleavage sites have not been mapped. Osteopontin-derived peptides can exert distinct biological
functions that may depend on their cleavage sites. We mapped the MMP-9 cleavage sites via LC-MS/MS analysis using label-free and N-terminal labeling methods, and compared them with those of MMP-2, -3, and -7. Each MMP yielded a unique cleavage profile with few overlapping cleavage sites. Using
synthetic peptides, we validated 3 sites for MMP-9 cleavage at amino acid positions 151–152, 193–194, and 195–196. Four peptides were synthesized based on the upstream- and downstream-generated fragments and were tested for biological activity in isolated cardiac fibroblasts.
Two peptides increased cardiac fibroblast migration rates post-wounding (p < 0.05 compared with the negative control). Our study highlights the importance of osteopontin processing, and confirms that different cleavage sites generate osteopontin peptides with distinct biological
functions.
Keywords: MMP-9; MPM-9; cardiac; cardiaque; cleavage sites; fibroblastes; fibroblasts; infarctus du myocarde; mass spectrometry; matrix metalloproteinases; myocardial infarction; métalloprotéinases matricielles; osteopontin; ostéopontine; peptides; proteomics; protéomique; sites de clivage; spectométrie de masse
Document Type: Research Article
Publication date: 01 January 2015
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