title: Evidence for the occurrence of membrane-type serine protease 1/matriptase on the basolateral sides of enterocytes.
abstract: MT-SP1 (membrane-type serine protease 1)/matriptase is an epithelial-derived integral membrane enzyme. The purpose of the present study was to examine whether the enzyme exists on the basolateral side of simple columnar epithelial cells, such as enterocytes, of normal adult animals. Using COS-1 monkey kidney cells transiently transfected with rat MT-SP1/matriptase expression plasmids, we found that the enzyme is post-translationally processed by the cleavage between Gly149 and Ser150, that a portion of the C-terminal part (Ser150-Val855) remains in the cells by association with the NTF (N-terminal fragment) (Met1-Gly149), while the other portions are released into the medium and that the release is increased on activation by co-expression with hepatocyte growth factor activator inhibitor type-1. Western-blot analysis of crude membranes prepared from rat jejunum demonstrated the presence of the NTF but negligible or no occurrence of the C-terminal part of the protein. Fractionation of the crude membranes by ultracentrifugation with Percoll followed by Western-blot analysis showed that the fractionation profile of the NTF correlated significantly with that of E-cadherin, an adhesion molecule on the lateral membrane. Immunostaining of the jejunum demonstrated the occurrence of the NTF on the lateral membranes but not on the apical membranes. These results suggest that considerable MT-SP1/matriptase molecules occur on the basolateral sides of normal epithelial cells and support our hypothesis that a possible physiological function of this enzyme is the control of epithelial-cell turnover by regulating cell-cell and/or cell-substratum adhesions.
authors.affiliation: Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan. tkmone@kais.kyoto-u.ac.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsuzuki
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Murai
authors.forename: Yuka
authors.initials: Y
authors.lastname: Miyake
authors.forename: Kuniyo
authors.initials: K
authors.lastname: Inouye
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Hirayasu
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Iwanaga
authors.forename: Tohru
authors.initials: T
authors.lastname: Fushiki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002448:Cell Adhesion; D002462:Cell Membrane / Q000201:enzymology*; D002522:Chlorocebus aethiops; D020895:Enterocytes / Q000201:enzymology*; D005786:Gene Expression Regulation; D007583:Jejunum / Q000166:cytology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D012697:Serine Endopeptidases / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D012697:Serine Endopeptidases; C485595:matriptase