[Abstract Title]. - Society for Neuroscience

Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 271.8/HH27
Topic: D.09.b. Receptors
Support: NIH Grant DK065742
EAM award from SIU SOM
Title: Activation of TRPV4 by direct mechanical force
Authors: *D. CAO, L. S. PREMKUMAR;
Pharmacol., Southern Illinois Univ. Sch. Med., Springfield, IL
Abstract: TRPV4 was first described as an osmosensor and recently it has been shown to be
activated by heat (>27°C), low pH, anandamide and the phorbol ester derivative, 4aPDD.
TRPV4 has been shown to be required for hypotonic stimulus-induced nociception and has been
considered as a mechanotransducer in primary afferent nociceptive nerve fibers. However, it is
still not clear whether TRPV4 is activated by direct mechanical force. In this study, we have
investigated the mechanosensitivity of TRPV4 and determined its modulation by PKC. Patch
clamp technique was used to record single channel current. Application of negative pressure via
the patch pipette activated single TRPV4 channel activity in cell-attached patches from
HEK293T cells heterologously expressing TRPV4, but not in vector transfected cells. The single
channel current has an amplitude of 5.6 ± 0.1 pA corresponding to a conductance of 93 ± 2 pS at
+ 60 mV. The single channel characteristics are similar to those activated by application of
4aPDD, a specific TRPV4 agonist. Negative pressure- and 4aPDD- induced single channel
activity was further potentiated by application of phorbol 12,13-dibutyrate (PDBu), a PKC
activator. The specificity of PKC action was confirmed by using the PKC inhibitor,
bisindolylmaleimide. In addition, TRPV4 channel activity could also be induced by sheer flow of
fluid and by hypotonic solution. These results suggest that TRPV4 is a mechanosensitive channel
and is sensitized by activation of PKC, which may play a crucial role in mechanosensitive
responses (This study was supported by grants from NIH (DK065742) and EAM award from
SIU SOM to L.S.P.).
Disclosures: D. Cao, None; L.S. Premkumar, NIH DK065742 to L.S.P., B. Research Grant
(principal investigator, collaborator or consultant and pending grants as well as grants already
received); EAM award from SIU SOM to L.S.P., B. Research Grant (principal investigator,
collaborator or consultant and pending grants as well as grants already received).
Poster
271. Mechanoreceptors