Osteopontin is proteolytically processed by matrix metalloproteinase 9

Merry L. Lindsey, Fouad A. Zouein, Yuan Tian, Rugmani Padmanabhan Iyer, Lisandra E. de Castro Brás

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)879-886
Number of pages8
JournalCanadian journal of physiology and pharmacology
Issue number10
StatePublished - Jan 19 2015
Externally publishedYes


  • Cardiac
  • Cleavage sites
  • Fibroblasts
  • MMP-9
  • Mass spectrometry
  • Matrix metalloproteinases
  • Myocardial infarction
  • Osteopontin
  • Peptides
  • Proteomics

ASJC Scopus subject areas

  • Physiology
  • Pharmacology
  • Physiology (medical)


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