Caenorhabditis elegans TRPA-1 functions in mechanosensation


Members of the transient receptor potential (TRP) ion channel family mediate diverse sensory transduction processes in both vertebrates and invertebrates. In particular, members of the TRPA subfamily have distinct thermosensory roles in Drosophila, and mammalian TRPA1 is postulated to have a function in noxious cold sensation and mechanosensation. Here we show that mutations in trpa-1, the C. elegans ortholog of mouse Trpa1, confer specific defects in mechanosensory behaviors related to nose-touch responses and foraging. trpa-1 is expressed and functions in sensory neurons required for these mechanosensory behaviors, and contributes to neural responses of these cells to touch, particularly after repeated mechanical stimulation. Furthermore, mechanical pressure can activate C. elegans TRPA-1 heterologously expressed in mammalian cells. Collectively, these data demonstrate that trpa-1 encodes an ion channel that can be activated in response to mechanical pressure and is required for mechanosensory neuron function, suggesting a possible role in mechanosensory transduction or modulation.

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Figure 1: TRPA-1::GFP fusion protein is expressed in neuron and non-neuronal cell types.
Figure 2: Effect of trpa-1 on head foraging movements.
Figure 3: trpa-1 mutants are defective in the head withdrawal reflex.
Figure 4: trpa-1 mutants have defects in reversal response to nose-touch, but are normal for ASH-mediated osmosensory and chemosensory avoidance behaviors.
Figure 5: Effects of trpa-1 on neural responses to nose-touch in OLQ and ASH.
Figure 6: Mechanical stimuli activate TRPA-1-expressing CHO cells.

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We thank G. Lesa for genomic DNA and technical advice, A. Huang for his assistance with the automated worm tracker, G. Story for technical assistance and T. Jegla for assistance and discussions. We would also like to thank C. Bargmann, Rockefeller University for providing constructs and for help finding a suitable promoter to image the OLQ neurons. A. Fire (Carnegie Institution of Washington) supplied us with GFP expression vectors. We would also like to thank M. de Bono, for comments and guidance in neuronal identification. We thank the C. elegans gene knockout project at Oklahoma Medical Research Facility for providing the ok999 strain, and the National Bioresource Project and the Mitani laboratory (Tokyo Women's Medical University) for providing the tm1402 strain. This research was partially supported by US National Institutes of Health grants R01DE016927 to A.P and R01DA016445 and R01DA018341 to W.R.S., and a Ruth Kirschstein Predoctoral Fellowship to K.S.K.

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Corresponding authors

Correspondence to Ardem Patapoutian or William R Schafer.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Fig. 1

Phylogenetic tree of TRPA subfamily. (PDF 356 kb)

Supplementary Fig. 2

C. elegans TRPA-1 is a member of the TRPA subfamily of TRP channels. (PDF 260 kb)

Supplementary Fig. 3

The full length cTRPA-1 GFP fusion, ljEx114 colocalizes with pdel-2::RFP in the Il1 and OLQ neurons. (PDF 679 kb)

Supplementary Fig. 4

C. elegans TRPA-1 is not required for body touch responses and normal thermotaxis. (PDF 1236 kb)

Supplementary Fig. 5

Baseline cameleon levels in wildtype and trpa-1 mutants, and raw imaging data. (PDF 1447 kb)

Supplementary Fig. 6

Mechanical stimuli activate TRPA-1-expressing CHO cells. (PDF 916 kb)

Supplementary Methods (PDF 117 kb)

Supplementary Results (PDF 160 kb)

Supplementary Video 1

Reversal response to nose touch. As animal makes a nose-on collision with an eyelash, 80% of the time a reversal or backward movement is initiated. (AVI 520 kb)

Supplementary Video 2

Head withdrawal response to nose touch. In addition to a reversal response, 15% of the time animals display a head withdrawal upon encounter with the eyelash. (AVI 299 kb)

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Kindt, K., Viswanath, V., Macpherson, L. et al. Caenorhabditis elegans TRPA-1 functions in mechanosensation. Nat Neurosci 10, 568–577 (2007).

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