title: Channel-forming peptide modulates transepithelial electrical conductance and solute permeability.
abstract: NC-1059, a synthetic channel-forming peptide, transiently increases transepithelial electrical conductance (g(TE)) and ion transport (as indicated by short-circuit current) across Madin-Darby canine kidney (MDCK) cell monolayers in a time- and concentration-dependent manner when apically exposed. g(TE) increases from <2 to >40 mS/cm(2) over the low to middle micromolar range. Dextran polymer (9.5 but not 77 kDa) permeates the monolayer following apical NC-1059 exposure, suggesting that modulation of the paracellular pathway accounts for changes in g(TE). However, concomitant alterations in junctional protein localization (zonula occludens-1, occludin) and cellular morphology are not observed. Effects of NC-1059 on MDCK g(TE) occur in nominally Cl(-)- and Na(+)-free apical media, indicating that permeation by these ions is not required for effects on g(TE), although two-electrode voltage-clamp assays with Xenopus oocytes suggest that both Cl(-) and Na(+) permeate NC-1059 channels with a modest Cl(-) permselectivity (P(Cl):P(Na) = 1.3). MDCK monolayers can be exposed to multiple NC-1059 treatments over days to weeks without diminution of response, alteration in the time course, or loss of responsiveness to physiological and pharmacological secretagogues. Together, these results suggest that NC-1059 represents a valuable tool to investigate tight junction regulation and may be a lead compound for therapeutic interventions.
authors.affiliation: Department of Anatomy and Physiology, 228 Coles Hall, Kansas State University, Manhattan, KS 66506, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Broughman
authors.forename: Robert M
authors.initials: RM
authors.lastname: Brandt
authors.forename: Christy
authors.initials: C
authors.lastname: Hastings
authors.forename: Takeo
authors.initials: T
authors.lastname: Iwamoto
authors.forename: John M
authors.initials: JM
authors.lastname: Tomich
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Schultz
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D016764:Cell Polarity / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism* / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism; D062793:Occludin; D010455:Peptides / Q000494:pharmacology; D010750:Phosphoproteins / Q000187:drug effects / Q000378:metabolism; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism*; D029867:Xenopus Proteins; D062826:Zonula Occludens-1 Protein
chemical_list: D007473:Ion Channels; D008565:Membrane Proteins; C487308:NC-1059; D062793:Occludin; D010455:Peptides; D010750:Phosphoproteins; C569045:TJP1 protein, Xenopus; D029867:Xenopus Proteins; D062826:Zonula Occludens-1 Protein