title: Mechanosensitive activation of CFTR by increased cell volume and hydrostatic pressure but not shear stress.
abstract: The cystic fibrosis transmembrane conductance regulator (CFTR) is a Cl(-) channel that is essential for electrolyte and fluid homeostasis. Preliminary evidence indicates that CFTR is a mechanosensitive channel. In lung epithelia, CFTR is exposed to different mechanical forces such as shear stress (Ss) and membrane distention. The present study questioned whether Ss and/or stretch influence CFTR activity (wild type, ∆F508, G551D). Human CFTR (hCFTR) was heterologously expressed in Xenopus oocytes and the response to the mechanical stimulus and forskolin/IBMX (FI) was measured by two-electrode voltage-clamp experiments. Ss had no influence on hCFTR activity. Injection of an intracellular analogous solution to increase cell volume alone did not affect hCFTR activity. However, hCFTR activity was augmented by injection after pre-stimulation with FI. The response to injection was similar in channels carrying the common mutations ∆F508 and G551D compared to wild type hCFTR. Stretch-induced CFTR activation was further assessed in Ussing chamber measurements using Xenopus lung preparations. Under control conditions increased hydrostatic pressure (HP) decreased the measured ion current including activation of a Cl(-) secretion that was unmasked by the CFTR inhibitor GlyH-101. These data demonstrate activation of CFTR in vitro and in a native pulmonary epithelium in response to mechanical stress. Mechanosensitive regulation of CFTR is highly relevant for pulmonary physiology that relies on ion transport processes facilitated by pulmonary epithelial cells.
authors.affiliation: Institute of Animal Physiology, Justus-Liebig-University Giessen, Giessen, Germany.
authors.forename: Constanze
authors.initials: C
authors.lastname: Vitzthum
authors.affiliation: Institute of Animal Physiology, Justus-Liebig-University Giessen, Giessen, Germany.
authors.forename: Wolfgang G
authors.initials: WG
authors.lastname: Clauss
authors.affiliation: Department of Physiology, University of Otago, Dunedin, New Zealand. Electronic address: martin.fronius@otago.ac.nz.
authors.forename: Martin
authors.initials: M
authors.lastname: Fronius
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D048429:Cell Size; D002712:Chlorides / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D005260:Female; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D006834:Hydrazines / Q000494:pharmacology; D006874:Hydrostatic Pressure; D015640:Ion Channel Gating / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D009154:Mutation; D009865:Oocytes / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D018408:Patch-Clamp Techniques; D033081:Shear Strength; D013314:Stress, Mechanical; D014982:Xenopus laevis
chemical_list: D002712:Chlorides; D006834:Hydrazines; C548779:N-(2-naphthalenyl)-((3,5-dibromo-2,4-dihydroxyphenyl)methylene)glycine hydrazide; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005576:Colforsin; D015056:1-Methyl-3-isobutylxanthine; D005998:Glycine
keywords: Cell volume, stretch, shear stress; Cystic fibrosis transmembrane conductance regulator; Mechanosensitive; Mechanotransduction