title: Regulation of pericellular proteolysis by hepatocyte growth factor activator inhibitor type 1 (HAI-1) in trophoblast cells.
abstract: Hepatocyte growth factor activator inhibitor type 1/serine protease inhibitor Kunitz type 1 (HAI-1/SPINT1) is a membrane-bound Kunitz-type serine protease inhibitor that is abundantly expressed on the surface of cytotrophoblasts, and is critically required for the formation of the placenta labyrinth in mice. HAI-1/SPINT1 regulates several membrane-associated cell surface serine proteases, with matriptase being the most cognate target. Matriptase degrades extracellular matrix protein such as laminin and activates other cell surface proteases including prostasin. This study aimed to analyze the role of HAI-1/SPINT1 in pericellular proteolysis of trophoblasts. In HAI-1/SPINT1-deficient mouse placenta, laminin immunoreactivity around trophoblasts was irregular and occasionally showed an intense punctate pattern, which differed significantly from the linear distribution along the basement membrane observed in wild-type placenta. To explore the molecular mechanism underlying this observation, we analyzed the effect of HAI-1/SPINT1 knock down (KD) on pericellular proteolysis in the human trophoblast cell line, BeWo. HAI-1/SPINT1-KD BeWo cells had increased amounts of cellular laminin protein and decreased laminin degradation activity in the culture supernatant. Subsequent analysis indicated that cell-associated matriptase was significantly decreased in KD cells whereas its mRNA level was not altered, suggesting an enhanced release and/or dislocation of matriptase in the absence of HAI-1/SPINT1. Moreover, prostasin activation and pericellular total serine protease activities were significantly suppressed by HAI-1/SPINT1 KD. These observations suggest that HAI-1/SPINT1 is critically required for the cell surface localization of matriptase in trophoblasts, and, in the absence of HAI-1/SPINT1, physiological activation of prostasin and other protease(s) initiated by cell surface matriptase may be impaired.
authors.affiliation: Department of Pathology, Faculty of Medicine, Section of Oncopathology and Regenerative Biology, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan.
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Kohama
authors.forename: Makiko
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Fukushima
authors.forename: Chen-Yong
authors.initials: CY
authors.lastname: Lin
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kataoka
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D006801:Humans; D007797:Laminin / Q000378:metabolism; D051379:Mice; D053491:Proteinase Inhibitory Proteins, Secretory / Q000494:pharmacology / Q000502:physiology*; D059748:Proteolysis; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases / Q000378:metabolism; D057057:Serine Proteases / Q000378:metabolism*; D014327:Trophoblasts / Q000201:enzymology* / Q000378:metabolism / Q000502:physiology; D000099271:Prostasin
chemical_list: D007797:Laminin; D053491:Proteinase Inhibitory Proteins, Secretory; D012697:Serine Endopeptidases; D057057:Serine Proteases; D000099271:Prostasin; C109149:SPINT1 protein, human; C485595:matriptase