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Structural basis of TRPA1 inhibition by HC-030031 utilizing species-specific differences
Rupali Gupta1,2, Shigeru Saito1,2, Yoshiharu Mori3
1Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, Japan.
Abstract:
Pain is a harmful sensation that arises from noxious stimuli. Transient receptor potential ankyrin 1 (TRPA1) is one target for studying pain mechanisms. TRPA1 is activated by various stimuli such as noxious cold, pungent natural products and environmental irritants. Since TRPA1 is an attractive target for pain therapy, a few TRPA1 antagonists have been developed and some function as analgesic agents. The responses of TRPA1 to agonists and antagonists vary among species and these species differences have been utilized to identify the structural basis of activation and inhibition mechanisms. The TRPA1 antagonist HC-030031 (HC) failed to inhibit frog TRPA1 (fTRPA1) and zebrafish TRPA1 activity induced by cinnamaldehyde (CA), but did inhibit human TRPA1 (hTRPA1) in a heterologous expression system. Chimeric studies between fTRPA1 and hTRPA1, as well as analyses using point mutants, revealed that a single amino acid residue (N855 in hTRPA1) significantly contributes to the inhibitory action of HC. Moreover, the N855 residue and the C-terminus region exhibited synergistic effects on the inhibition by HC. Molecular dynamics simulation suggested that HC stably binds to hTRPA1-N855. These findings provide novel insights into the structure-function relationship of TRPA1 and could lead to the development of more effective analgesics targeted to TRPA1.
Insights
Transient receptor potential ankyrin 1 (TRPA1) antagonists show species-specific activity. A single amino acid (N855) in human TRPA1 is key to HC-030031 inhibition, offering insights for novel pain therapies.
Area of Science:
- Neuroscience
- Pharmacology
- Molecular Biology
Background:
- Pain perception involves noxious stimuli, with Transient Receptor Potential Ankyrin 1 (TRPA1) channels as key targets.
- TRPA1 channels are activated by diverse stimuli including cold, irritants, and natural products.
- TRPA1 antagonists are explored for analgesic potential, but species-specific responses complicate drug development.
Purpose of the Study:
- To investigate the structural basis for species-specific inhibition of TRPA1 channels by the antagonist HC-030031.
- To identify key amino acid residues and regions involved in HC-030031's inhibitory mechanism on TRPA1.
Main Methods:
- Utilized heterologous expression systems for human (hTRPA1) and frog (fTRPA1) TRPA1 channels.
- Performed chimeric studies and point mutagenesis to analyze functional differences.
- Employed molecular dynamics simulations to model antagonist binding.
Main Results:
- The TRPA1 antagonist HC-030031 inhibited hTRPA1 but not fTRPA1 or zebrafish TRPA1 activity.
- A single amino acid residue, N855 in hTRPA1, was identified as crucial for HC-030031's inhibitory action.
- Synergistic effects between N855 and the C-terminus region influenced HC inhibition; molecular dynamics confirmed stable HC binding to hTRPA1-N855.
Conclusions:
- Species differences in TRPA1 channel inhibition by HC-030031 are attributed to specific amino acid residues, particularly N855.
- Understanding these structure-function relationships can guide the development of more effective TRPA1-targeted analgesics.
