Larsen, Brian R2; Steffensen, Simon D2; Nielsen, Nis V L3; Friis, Stine2; Godiksen, Sine2; Bornholdt, Jette4; Soendergaard, Christoffer5; Nonboe, Annika Weile5; Andersen, Martin N.6; Poulsen, Steen S.6; Szabo, Roman7; Bugge, Thomas H.7; Lin, Chen-Yong8; Skovbjerg, Hann29; Jensen, Jan Kristian11; Vogel, Lotte K5
1 Department of Molecular Biology and Genetics - Department of Molecular Biology, Department of Molecular Biology and Genetics, Science and Technology, Aarhus University2 Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen3 Department of Molecular Biology and Genetics - Aarhus University4 Department of Biology, Faculty of Science, University of Copenhagen5 Department of Cellular and Molecular Medicine, Faculty of Health Science, University of Copenhagen6 Department of Biomedical Sciences, Faculty of Health Science, University of Copenhagen7 Proteases and Tissue Remodeling Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD 20892, USA8 Department of Biochemistry and Molecular Biology, Greenebaum Cancer Centre, University of Maryland, Baltimore, MD 21201, USA9 Medical Department, Amager Hospital, Copenhagen10 ST Administrative Centre - ST Estates Facilities, ST Administrative Centre, Science and Technology, Aarhus University11 ST Administrative Centre - ST Estates Facilities, ST Administrative Centre, Science and Technology, Aarhus University
Hepatocyte growth factor activator inhibitor-2 (HAI-2) is an inhibitor of many proteases in vitro, including the membrane-bound serine protease, matriptase. Studies of knock-out mice have shown that HAI-2 is essential for placental development only in mice expressing matriptase, suggesting that HAI-2 is important for regulation of matriptase. Previous studies have shown that recombinant expression of matriptase was unsuccessful unless co-expressed with another HAI, HAI-1. In the present study we show that when human matriptase is recombinantly expressed alone in the canine cell line MDCK, then human matriptase mRNA can be detected and the human matriptase ectodomain is shed to the media, suggesting that matriptase expressed alone is rapidly transported through the secretory pathway and shed. Whereas matriptase expressed together with HAI-1 or HAI-2 accumulates on the plasma membrane where it is activated, as judged by cleavage at Arg614 and increased peptidolytic activity of the cell extracts. Mutagenesis of Kunitz domain 1 but not Kunitz domain 2 abolished this function of HAI-2. HAI-2 seems to carry out its function intracellularly as this is where the vast majority of HAI-2 is located and since HAI-2 could not be detected on the basolateral plasma membrane where matriptase resides. However, minor amounts of HAI-2 not undergoing endocytosis could be detected on the apical plasma membrane. Our results suggest that Kunitz domain 1 of HAI-2 cause matriptase to accumulate in a membrane-bound form on the basolateral plasma membrane.
Experimental Cell Research, 2013, Vol 319, Issue 6, p. 918-929