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Post‐secretory activation of Paneth cell α‐defensins in the cecal and colonic lumen of matrix metalloproteinase‐7‐null mice
Author(s) -
Mastroianni Jennifer Rose,
Costales Jessica K.,
Salzman Nita H.,
Ouellette Andre J.
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.952.7
Subject(s) - cecum , ileum , paneth cell , matrix metalloproteinase , chemistry , jejunum , secretion , biochemistry , defensin , microbiology and biotechnology , extracellular matrix , small intestine , biology , peptide , ecology
In mice, Paneth cell α‐defensins, termed cryptdins (Crps), are converted intracellularly from inactive precursors to bactericidal forms by matrix metalloproteinase‐7 (MMP‐7). Because it is possible that other extracellular proteinases may be capable of similar processing, we tested whether secreted proCrps are converted to active forms in the MMP‐7−/− mouse. Protein extracts from complete (organ plus luminal contents) ileum, cecum, and colon of MMP‐7−/− and wild‐type C57Bl/6 mice were compared by gel permeation chromatography and acid‐urea (AU)‐PAGE. As anticipated, MMP‐7−/− ileum lacked appreciable levels of processed Crps. However, high levels of apparent Crps were purified from the cecum and colon of MMP‐7−/− mice. N‐terminal sequencing and mass spectrometry identified α‐defensins consisting of a mixture of native Crps, N‐terminally truncated Crps, and Crps with elongated N termini that retain proregion residues near the proregion‐Crp junction. Thus, secreted mouse proCrps may be processed in the large bowel lumen, even in the absence of the intracellular activating enzyme. Also, the MMP‐7−/− mouse may be a useful model of innate mucosal immunity in the small intestine, but the knockout is not α‐defensin deficient in cecum or distal colon, downstream from the site of precursor secretion in small intestinal crypts of Lieberkühn. Supported by NIH grants DK044632, AI059346, and AI057757.