A synthetic peptide based on a glycine-gated chloride channel induces a novel chloride conductance in isolated epithelial cells.
CK(4)-M2GlyR, an aqueous soluble peptide derived from the transmembrane M2 segment of the glycine-gated Cl(-) channel found in postsynaptic membranes of the central nervous system, has previously been shown to increase transepithelial Cl(-) and fluid secretion of epithelial monolayers. The goal of this study was to determine whether CK(4)-M2GlyR exerts these effects via formation of a novel chloride conductance pathway, modulation of endogenous chloride channel activity, or a combination of these effects. Ionic currents were recorded from isolated epithelial cells before and after treatment with the peptide using the whole-cell configuration of the patch-clamp technique. CK(4)-M2GlyR increased whole-cell Cl(-) currents in all epithelial cell lines that were studied, including: Madin-Darby canine kidney cells, a human colonic epithelial cell line (T84), and airway epithelial cells derived from a human cystic fibrosis patient (IB3-1). No evidence was found for modulation of endogenous Cl(-) channels by CK(4)-M2GlyR based on both the electrophysiological properties of the observed currents and the pharmacological profile of the CK(4)-M2GlyR-induced current. These results suggest that CK(4)-M2GlyR increases Cl(-) permeability in epithelial cells directly, by forming a distinct conduction pathway in cell membranes.
Mitchell
K E
KE
Department of Anatomy and Physiology, Kansas State University, Manhattan 66506-5602, USA.
Iwamoto
T
T
Tomich
J
J
Freeman
L C
LC
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002469:Cell Separation; D018118:Chloride Channels / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000502:physiology; D004285:Dogs; D004553:Electric Conductivity; D004594:Electrophysiology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D005998:Glycine / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology; D012996:Solutions; D055672:Static Electricity
C505032:CFTR protein, human; D018118:Chloride Channels; D002712:Chlorides; D036341:Intercellular Signaling Peptides and Proteins; C111087:K4-M2GlyR protein, synthetic; D010455:Peptides; D012996:Solutions; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005998:Glycine