Molecular characterization of TRPA1 channel activation by cysteine-reactive inflammatory mediators

Channels (Austin). Jul-Aug 2008;2(4):287-98. doi: 10.4161/chan.2.4.6745. Epub 2008 Jul 6.

Abstract

TRPA1 is a member of the transient receptor potential (TRP) cation channel family, and is predominantly expressed in nociceptive neurons of dorsal root ganglia (DRG) and trigeminal ganglia. Activation of TRPA1 by environmental irritants such as mustard oil, allicin and acrolein causes acute pain. However, the endogenous ligands that directly activate TRPA1 remain elusive in inflammation. Here, we show that a variety of inflammatory mediators (15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), nitric oxide (NO), hydrogen peroxide (H(2)O(2)), and proton (H(+))) activate human TRPA1 heterologously expressed in HEK cells. These inflammatory mediators induced robust Ca(2+) influx in a subset of mouse DRG neurons. The TRP channel blocker ruthenium red almost completely inhibited neuronal responses by 15d-PGJ(2) and NO, but partially suppressed responses to H(2)O(2) and H(+). Functional characterization of site-directed cysteine mutants of TRPA1 in combination with labeling experiments using biotinylated 15d-PGJ(2) demonstrated that modifications of cytoplasmic N-terminal cysteines (Cys421 and Cys621) were responsible for the activation of TRPA1 by 15d-PGJ(2). In TRPA1 responses to other cysteine-reactive inflammatory mediators, such as NO and H(2)O(2), the extent of impairment by respective cysteine mutations differed from those in TRPA1 responses to 15d-PGJ(2). Interestingly, the Cys421 mutation critically impaired the TRPA1 response to H(+) as well. Our findings suggest that TRPA1 channels are targeted by an array of inflammatory mediators to elicit inflammatory pain in the nervous system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Channels / metabolism*
  • Cell Line
  • Cysteine / chemistry*
  • Ganglia, Spinal / metabolism
  • Humans
  • Hydrogen Peroxide / metabolism
  • Inflammation*
  • Mice
  • Models, Biological
  • Nerve Tissue Proteins / metabolism*
  • Nitric Oxide / metabolism
  • Pain Management
  • Prostaglandin D2 / analogs & derivatives
  • Prostaglandin D2 / metabolism
  • TRPA1 Cation Channel
  • Transient Receptor Potential Channels / metabolism*
  • Trigeminal Ganglion / metabolism

Substances

  • 15-deoxyprostaglandin J2
  • Calcium Channels
  • Nerve Tissue Proteins
  • TRPA1 Cation Channel
  • TRPA1 protein, human
  • Transient Receptor Potential Channels
  • Trpa1 protein, mouse
  • Nitric Oxide
  • Hydrogen Peroxide
  • Cysteine
  • Prostaglandin D2