title: Simultaneous activation and hepatocyte growth factor activator inhibitor 1-mediated inhibition of matriptase induced at activation foci in human mammary epithelial cells.
abstract: Activation of single-chain, latent matriptase, a type II transmembrane serine protease, depends on the weak proteolytic activity of its own zymogen as well as its cognate inhibitor, hepatocyte growth factor activator inhibitor 1 (HAI-1). Oligomerization of matriptase zymogens and HAI-1, and probably its interaction with other proteins, has been proposed to occur during matriptase activation. In the present study, we examined the cellular events associated with matriptase activation triggered either by the physiological inducer sphingosine 1-phosphate (S1P) or by a chemical inducer, the polyanionic compound suramin. S1P-induced matriptase translocation to cell-cell contacts, where it is activated, is an F-actin polymerization-dependent process. Conversely, suramin-induced matriptase accumulation and activation at vesicle-like structures is an F-actin polymerization-independent process. While matriptase activation can occur at different subcellular locations, both S1P- and suramin-induced matriptase accumulation form unique subcellular structures, termed activation foci, where oligomerization of matriptase zymogens and HAI-1 may occur, promoting matriptase activation. Furthermore, matriptase activation may be regulated by intracellular signaling, because Ro 31-8220, a bisindolylmaleimide protein kinase C inhibitor, inhibited both S1P- and suramin-induced activation. The requirement of HAI-1 for matriptase activation and the coincidence of HAI-1 and matriptase in activation foci apparently provide rapid access of HAI-1 for the inhibition of matriptase immediately after its activation. Indeed, all activated matriptase was detected in complexes with HAI-1 only 5 min after suramin stimulation. The close temporospatial coupling of matriptase activation with its inhibition suggests that the proteolytic activity of this enzyme must be well controlled and that the proteolysis of matriptase substrates may be tightly regulated by this mechanism.
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown Univ. Medical Center, 3970 Reservoir Rd. NW, Washington, DC 20057-1412, USA.
authors.forename: Ming-Shyue
authors.initials: MS
authors.lastname: Lee
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Kiyomiya
authors.forename: Christelle
authors.initials: C
authors.lastname: Benaud
authors.forename: Robert B
authors.initials: RB
authors.lastname: Dickson
authors.forename: Chen-Yong
authors.initials: CY
authors.lastname: Lin
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology; D008246:Lysophospholipids / Q000494:pharmacology; D042361:Mammary Glands, Human / Q000187:drug effects / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D021381:Protein Transport / Q000187:drug effects; D053491:Proteinase Inhibitory Proteins, Secretory; D012697:Serine Endopeptidases / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013498:Suramin / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids; D008562:Membrane Glycoproteins; D053491:Proteinase Inhibitory Proteins, Secretory; C109149:SPINT1 protein, human; C015482:protein kinase modulator; C060506:sphingosine 1-phosphate; D013498:Suramin; D012697:Serine Endopeptidases; C485595:matriptase; D013110:Sphingosine