title: Activation of the amiloride-sensitive epithelial sodium channel by the serine protease mCAP1 expressed in a mouse cortical collecting duct cell line.
abstract: This study examines whether serine proteases can activate the amiloride-sensitive sodium channel (ENaC) in mammalian kidney epithelial cells. The transepithelial sodium transport assessed by amiloride-sensitive short-circuit current appears to be sensitive to aprotinin, a protease inhibitor in a mouse cortical collecting duct cell line (mpkCCD(c14)). This result indicated that serine proteases may be implicated in the regulation of ENaC-mediated sodium transport. Using degenerated oligonucleotides to a previously isolated serine protease from Xenopus, xCAP1 (channel activating protease), a novel full-length serine protease (mCAP1), has been isolated and characterized. RNA analysis showed a broad pattern of expression in tissues (kidney, lung, colon, and salivary glands) expressing ENaC. Reverse transcription-PCR experiments also showed that mCAP1 was abundantly expressed in proximal tubule cells and was also expressed in intact and cultured collecting duct cells. Coexpression of the Xenopus, rat, or human alpha-, beta-, and gamma-ENaC subunits in Xenopus oocytes also showed that mCAP1 induces a significant increase in ENaC-mediated current accompanied by a decrease of channel molecules at the cell surface. It is proposed that this novel mouse channel activating protease may act as a regulator of ENaC within the kidney.
authors.affiliation: Institut de Pharmacologie et de Toxicologie, Université de Lausanne, Switzerland.
authors.forename: Grégoire
authors.initials: G
authors.lastname: Vuagniaux
authors.affiliation: Institut de Pharmacologie et de Toxicologie, Université de Lausanne, Switzerland.
authors.forename: Véronique
authors.initials: V
authors.lastname: Vallet
authors.affiliation: Institut de Pharmacologie et de Toxicologie, Université de Lausanne, Switzerland.
authors.forename: Nicole Fowler
authors.initials: NF
authors.lastname: Jaeger
authors.affiliation: Institut de Pharmacologie et de Toxicologie, Université de Lausanne, Switzerland.
authors.forename: Corinne
authors.initials: C
authors.lastname: Pfister
authors.affiliation: Institut Nationale de la Santé et de la Recherche Médicale U478, Institut Fédératif de Recherche, Paris Cedex, France.
authors.forename: Marcelle
authors.initials: M
authors.lastname: Bens
authors.affiliation: Institut Nationale de la Santé et de la Recherche Médicale U478, Institut Fédératif de Recherche, Paris Cedex, France.
authors.forename: Nicolette
authors.initials: N
authors.lastname: Farman
authors.affiliation: Institut Nationale de la Santé et de la Recherche Médicale U478, Institut Fédératif de Recherche, Paris Cedex, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Courtois-Coutry
authors.affiliation: Institut Nationale de la Santé et de la Recherche Médicale U478, Institut Fédératif de Recherche, Paris Cedex, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Vandewalle
authors.affiliation: Institut de Pharmacologie et de Toxicologie, Université de Lausanne, Switzerland.
authors.forename: Bernard C
authors.initials: BC
authors.lastname: Rossier
authors.affiliation: Institut de Pharmacologie et de Toxicologie, Université de Lausanne, Switzerland.
authors.forename: Edith
authors.initials: E
authors.lastname: Hummler
mesh_terms: D000584:Amiloride / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D007611:Aprotinin / Q000494:pharmacology; D015152:Blotting, Northern; D002460:Cell Line; D018076:DNA, Complementary; D004232:Diuretics / Q000494:pharmacology*; D004594:Electrophysiology; D006801:Humans; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D015222:Sodium Channels / Q000187:drug effects* / Q000378:metabolism*; D014981:Xenopus; D029867:Xenopus Proteins; D000099271:Prostasin
chemical_list: D000584:Amiloride; D007611:Aprotinin; D018076:DNA, Complementary; D004232:Diuretics; D012333:RNA, Messenger; D012697:Serine Endopeptidases; D015842:Serine Proteinase Inhibitors; D012964:Sodium; D015222:Sodium Channels; D029867:Xenopus Proteins; D000099271:Prostasin; C108632:Cap1 protein, Xenopus