title: TRPV4-mediated regulation of epithelial permeability.
abstract: TRPV4 is a calcium-permeable channel activated by extracellular hypotonicity, polyunsaturated fatty acids, phorbol esters, and heat. We show that TRPV4 is localized in the basolateral membrane of the mouse mammary cell line HC11. Activation of TRPV4 caused an increase in the intracellular Ca(2+) concentration through influx of extracellular Ca(2+), triggering two independent chains of events: 1) a rapid increase in transcellular conductance through the activation of apical large conductance calcium-activated (BK) potassium channels that were blockable by paxilline; 2) a slow increase in paracellular permeability for small solutes. The latter effect was accompanied by a down-regulation of the tight junctional proteins claudin -1, -3, -4, -5, -7, and -8 and by dramatic changes in tight junction morphology, including frequent large breaks in the tight junction strands. This dual modulation of epithelial permeability after TRPV4 activation may be involved in regulating the tonicity across mammary gland epithelia. TRPV4 activation may also be responsible for exudation and edema formation during inflammation processes.-Reiter, B., Kraft, R., Günzel, D., Zeissig, S., Schulzke, J-D., Fromm, M., Harteneck, C. TRPV4-mediated regulation of epithelial permeability.
authors.affiliation: Institut für Pharmakologie, Charité Campus Benjamin Franklin, Berlin, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Reiter
authors.forename: Robert
authors.initials: R
authors.lastname: Kraft
authors.forename: Dorothee
authors.initials: D
authors.lastname: Günzel
authors.forename: Sebastian
authors.initials: S
authors.lastname: Zeissig
authors.forename: Jörg-Dieter
authors.initials: JD
authors.lastname: Schulzke
authors.forename: Michael
authors.initials: M
authors.lastname: Fromm
authors.forename: Christian
authors.initials: C
authors.lastname: Harteneck
mesh_terms: D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002455:Cell Division; D002460:Cell Line; D002463:Cell Membrane Permeability; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D005260:Female; D005614:Freeze Fracturing; D008321:Mammary Glands, Animal / Q000502:physiology*; D008353:Mannitol / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D018408:Patch-Clamp Techniques; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050916:TRPV Cation Channels / Q000235:genetics / Q000502:physiology*
chemical_list: D050916:TRPV Cation Channels; C486576:Trpv4 protein, mouse; D008353:Mannitol; D002118:Calcium