1. Modulation of the Transient Receptor Potential Vanilloid Channel TRPV4 by 4α-Phorbol Esters: A Structure−Activity Study
- Author
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Minassi Alberto, Alberto Pagani, Bernd Nilius, Grzegorz Owsianik, Giovanni Appendino, Jean Prenen, Thomas Kjær Klausen, Stine F. Pedersen, Else K. Hoffmann, and Abdellah Ech-Chahad
- Subjects
TRPV4 ,Dose-Response Relationship, Drug ,Esterification ,Chemistry ,Stereochemistry ,Acylation ,TRPV1 ,Rational design ,TRPV Cation Channels ,Ring (chemistry) ,Small molecule ,Cell Line ,Mice ,Structure-Activity Relationship ,Phorbol Esters ,Drug Discovery ,Animals ,Humans ,Molecular Medicine ,Structure–activity relationship ,Binding site ,Ion channel - Abstract
The mechanism of activation of the transient receptor potential vanilloid 4 (TRPV4) channel by 4alpha-phorbol esters was investigated by combining information from chemical modification of 4alpha-phorbol-didecanoate (4alpha-PDD, 2a), site-directed mutagenesis, Ca(2+) imaging, and electrophysiology. Binding of 4alpha-phorbol esters occurs in a loop in the TM3-TM4 domain of TRPV4 that is analogous to the capsaicin binding site of TRPV1, and the ester decoration of ring C and the A,B ring junction are critical for activity. The lipophilic ester groups on ring C serve mainly as a steering element, affecting the orientation of the diterpenoid core into the ligand binding pocket, while the nature of the A,B ring junction plays an essential role in the Ca(2+)-dependence of the TRPV4 response. Taken together, our results show that 4alpha-phorbol is a useful template to investigate the molecular details of TRPV4 activation by small molecules and obtain information for the rational design of structurally simpler ligands for this ion channel.
- Published
- 2009
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