Modulation of TRPV4 gating by intra- and extracellular Ca2+.
We have studied the modulation of gating properties of the Ca2+-permeable, cation channel TRPV4 transiently expressed in HEK293 cells. The phorbol ester 4alphaPDD transiently activated a current through TRPV4 in the presence of extracellular Ca2+. Increasing the concentration of extracellular Ca2+ ([Ca2+](e)) reduced the current amplitude and accelerated its decay. This decay was dramatically delayed in the absence of [Ca2+](e). It was also much slower in the presence of [Ca2+](e) in a mutant channel, obtained by a point mutation in the 6th transmembrane domain, F707A. Mutant channels, containing a single mutation in the C-terminus of TRPV4 (E797), were constitutively open. In conclusion, gating of the 4alphaPDD-activated TRPV4 channel depends on both extra- and intracellular Ca2+, and is modulated by mutations of single amino acid residues in the 6th transmembrane domain and the C-terminus of the TRPV4 protein.
Watanabe
Hiroyuki
H
Department of Physiology, Laboratorium voor Fysiologie, Campus Gasthuisberg, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium.
Vriens
Joris
J
Janssens
Annelies
A
Wondergem
Robert
R
Droogmans
Guy
G
Nilius
Bernd
B
D019943:Amino Acid Substitution; D027682:Cation Transport Proteins / Q000187:drug effects / Q000502:physiology*; D002412:Cations / Q000378:metabolism*; D002478:Cells, Cultured; D004594:Electrophysiology; D005110:Extracellular Space; D006801:Humans; D007365:Intercellular Junctions; D015640:Ion Channel Gating / Q000502:physiology*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D009154:Mutation; D010704:Phorbols / Q000494:pharmacology*; D050916:TRPV Cation Channels
D027682:Cation Transport Proteins; D002412:Cations; D007473:Ion Channels; D010704:Phorbols; D050916:TRPV Cation Channels; C416986:TRPV4 protein, human; C033085:phorbol