title: A recombinant matriptase causes an increase in caspase-3 activity in a small-intestinal epithelial IEC-6 line cultured on fibronectin-coated plates.
abstract: Matriptase is an epithelial-derived type-II transmembrane serine protease. This protease is expressed prominently in the villus tip of small-intestinal epithelia at which senescent cells undergo shedding and/or apoptosis. The basement membrane of epithelial cells, including small-intestinal epithelial cells, contains extracellular matrix (ECM) proteins such as fibronectin and laminin. We found previously that high concentrations of a recombinant matriptase catalytic domain (r-MatCD) (e.g. 1 μM) caused an increased detachment of and increases in the activity of apoptotic effector caspase-3 in a rat small-intestinal epithelial IEC-6 line cultured on laminin-coated plates and proposed that at sites with its high level of expression, matriptase contributes to promoting shedding and/or detachment-induced death of epithelial cells through a mechanism mediating loss of cell-ECM adhesion. In this study, we found that even without increasing cell detachment, a high concentration of r-MatCD causes an increase in caspase-3 activity in IEC-6 cells cultured on fibronectin-coated plates, suggesting that the recombinant matriptase can cause apoptosis by a mechanism unrelated to cell detachment. Also, r-MatCD-treated IEC-6 cells on fibronectin were found to display spindle-like morphological changes. We suggest that r-MatCD causes apoptosis of IEC-6 on fibronectin by a mechanism involving the disruption of cell integrity.
authors.affiliation: Laboratory of Nutrition, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
authors.forename: Seiya
authors.initials: S
authors.lastname: Mochida
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsuzuki
authors.forename: Kuniyo
authors.initials: K
authors.lastname: Inouye
authors.forename: Tohru
authors.initials: T
authors.lastname: Fushiki