Potent and specific inhibition of the biological activity of the type-II transmembrane serine protease matriptase by the cyclic microprotein MCoTI-II.
Matriptase is a type-II transmembrane serine protease involved in epithelial homeostasis in both health and disease, and is implicated in the development and progression of a variety of cancers. Matriptase mediates its biological effects both via as yet undefined substrates and pathways, and also by proteolytic cleavage of a variety of well-defined protein substrates, several of which it shares with the closely-related protease hepsin. Development of targeted therapeutic strategies will require discrimination between these proteases. Here we have investigated cyclic microproteins of the squash Momordica cochinchinensis trypsin-inhibitor family (generated by total chemical synthesis) and found MCoTI-II to be a high-affinity (Ki 9 nM) and highly selective (> 1,000-fold) inhibitor of matriptase. MCoTI-II efficiently inhibited the proteolytic activation of pro-hepatocyte growth factor (HGF) by matriptase but not by hepsin, in both purified and cell-based systems, and inhibited HGF-dependent cell scattering. MCoTI-II also selectively inhibited the invasion of matriptase-expressing prostate cancer cells. Using a model of epithelial cell tight junction assembly, we also found that MCoTI-II could effectively inhibit the re-establishment of tight junctions and epithelial barrier function in MDCK-I cells after disruption, consistent with the role of matriptase in regulating epithelial integrity. Surprisingly, MCoTI-II was unable to inhibit matriptase-dependent proteolytic activation of prostasin, a GPI-anchored serine protease also implicated in epithelial homeostasis. These observations suggest that the unusually high selectivity afforded by MCoTI-II and its biological effectiveness might represent a useful starting point for the development of therapeutic inhibitors, and further highlight the role of matriptase in epithelial maintenance.
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Vincent Ellis, PhD, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK, Tel.: +44 1603 592570, E-mail: v.ellis@uea.ac.uk.
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D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D047169:Cyclotides / Q000494:pharmacology*; D004285:Dogs; D017097:Electric Impedance; D057809:HEK293 Cells; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D008297:Male; D058990:Molecular Targeted Therapy; D009361:Neoplasm Invasiveness; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000473:pathology; D011498:Protein Precursors / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D013379:Substrate Specificity; D019108:Tight Junctions / Q000187:drug effects / Q000201:enzymology; D013997:Time Factors; D014162:Transfection; D000099271:Prostasin
D047169:Cyclotides; D017228:Hepatocyte Growth Factor; D011498:Protein Precursors; D012697:Serine Endopeptidases; D015842:Serine Proteinase Inhibitors; D000099271:Prostasin; C086013:pro-hepatocyte growth factor; C409923:trypsin inhibitor MCoTI-II; C485596:ST14 protein, human
Serine protease; cyclotide; epithelial cell; hepatocyte growth factor; matriptase; protease inhibitor; tight junctions