Author:

Keywords:

Amino Acid Substitution, Cation Transport Proteins, Cations, Cells, Cultured, Electrophysiology, Extracellular Space, Humans, Intercellular Junctions, Ion Channel Gating, Ion Channels, Mutation, Phorbols, Research Support, Non-U.S. Gov't, TRPV Cation Channels, Science & Technology, Life Sciences & Biomedicine, Cell Biology, TRP channels, TRPV family, Ca2+-dependent inactivation, structure-function relationship, ACTIVATED CALCIUM-CHANNEL, HEAT-EVOKED ACTIVATION, CATION CHANNEL, PORE PROPERTIES, ION-CHANNEL, PERMEATION, CURRENTS, OTRPC4, FAMILY, TRP12, 0601 Biochemistry and Cell Biology, 0606 Physiology, 1116 Medical Physiology, Biochemistry & Molecular Biology, 3101 Biochemistry and cell biology, 3208 Medical physiology

Abstract:

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.