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Drosophila painless is a Ca2+-requiring channel activated by noxious heat.
J Neurosci. 2008 Oct 01; 28(40):9929-38.JN

Abstract

Thermal changes activate some members of the transient receptor potential (TRP) ion channel super family. They are primary sensors for detecting environmental temperatures. The Drosophila TRP channel Painless is believed responsible for avoidance of noxious heat because painless mutant flies display defects in heat sensing. However, no studies have proven its heat responsiveness. We show that Painless expressed in human embryonic kidney-derived 293 (HEK293) cells is a noxious heat-activated, Ca(2+)-permeable channel, and the function is mostly dependent on Ca(2+). In Ca(2+)-imaging, Painless mediated a robust intracellular Ca(2+) (Ca(2+)(i)) increase during heating, and it showed heat-evoked inward currents in whole-cell patch-clamp mode. Ca(2+) permeability was much higher than that of other cations. Heat-evoked currents were negligible in the absence of extracellular Ca(2+) (Ca(2+)(o)) and Ca(2+)(i), whereas 200 nm Ca(2+)(i) enabled heat activation of Painless. Activation kinetics were significantly accelerated in the presence of Ca(2+)(i). The temperature threshold for Painless activation was 42.6 degrees C in the presence of Ca(2+)(i), whereas the threshold was significantly increased to 44.1 degrees C when only Ca(2+)(o) was present. Temperature thresholds were further reduced after repetitive heating in a Ca(2+)-dependent manner. Ca(2+)-dependent heat activation of Painless was observed at the single-channel level in excised membranes. We found that a Ca(2+)-regulatory site is located in the N-terminal region of Painless. Painless-expressing HEK293 cells were insensitive to various thermosensitive TRP channel activators including allyl isothiocyanate, whereas mammalian TRPA1 inhibitors, ruthenium red, and camphor, reversibly blocked heat activation of Painless. Our results demonstrate that Painless is a direct sensor for noxious heat in Drosophila.

Authors+Show Affiliations

Section of Cell Signaling, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki 444-8787, Japan.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18829951

Citation

Sokabe, Takaaki, et al. "Drosophila Painless Is a Ca2+-requiring Channel Activated By Noxious Heat." The Journal of Neuroscience : the Official Journal of the Society for Neuroscience, vol. 28, no. 40, 2008, pp. 9929-38.
Sokabe T, Tsujiuchi S, Kadowaki T, et al. Drosophila painless is a Ca2+-requiring channel activated by noxious heat. J Neurosci. 2008;28(40):9929-38.
Sokabe, T., Tsujiuchi, S., Kadowaki, T., & Tominaga, M. (2008). Drosophila painless is a Ca2+-requiring channel activated by noxious heat. The Journal of Neuroscience : the Official Journal of the Society for Neuroscience, 28(40), 9929-38. https://doi.org/10.1523/JNEUROSCI.2757-08.2008
Sokabe T, et al. Drosophila Painless Is a Ca2+-requiring Channel Activated By Noxious Heat. J Neurosci. 2008 Oct 1;28(40):9929-38. PubMed PMID: 18829951.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Drosophila painless is a Ca2+-requiring channel activated by noxious heat. AU - Sokabe,Takaaki, AU - Tsujiuchi,Seiya, AU - Kadowaki,Tatsuhiko, AU - Tominaga,Makoto, PY - 2008/10/3/pubmed PY - 2008/10/18/medline PY - 2008/10/3/entrez SP - 9929 EP - 38 JF - The Journal of neuroscience : the official journal of the Society for Neuroscience JO - J Neurosci VL - 28 IS - 40 N2 - Thermal changes activate some members of the transient receptor potential (TRP) ion channel super family. They are primary sensors for detecting environmental temperatures. The Drosophila TRP channel Painless is believed responsible for avoidance of noxious heat because painless mutant flies display defects in heat sensing. However, no studies have proven its heat responsiveness. We show that Painless expressed in human embryonic kidney-derived 293 (HEK293) cells is a noxious heat-activated, Ca(2+)-permeable channel, and the function is mostly dependent on Ca(2+). In Ca(2+)-imaging, Painless mediated a robust intracellular Ca(2+) (Ca(2+)(i)) increase during heating, and it showed heat-evoked inward currents in whole-cell patch-clamp mode. Ca(2+) permeability was much higher than that of other cations. Heat-evoked currents were negligible in the absence of extracellular Ca(2+) (Ca(2+)(o)) and Ca(2+)(i), whereas 200 nm Ca(2+)(i) enabled heat activation of Painless. Activation kinetics were significantly accelerated in the presence of Ca(2+)(i). The temperature threshold for Painless activation was 42.6 degrees C in the presence of Ca(2+)(i), whereas the threshold was significantly increased to 44.1 degrees C when only Ca(2+)(o) was present. Temperature thresholds were further reduced after repetitive heating in a Ca(2+)-dependent manner. Ca(2+)-dependent heat activation of Painless was observed at the single-channel level in excised membranes. We found that a Ca(2+)-regulatory site is located in the N-terminal region of Painless. Painless-expressing HEK293 cells were insensitive to various thermosensitive TRP channel activators including allyl isothiocyanate, whereas mammalian TRPA1 inhibitors, ruthenium red, and camphor, reversibly blocked heat activation of Painless. Our results demonstrate that Painless is a direct sensor for noxious heat in Drosophila. SN - 1529-2401 UR - https://www.unboundmedicine.com/medline/citation/18829951/Drosophila_painless_is_a_Ca2+_requiring_channel_activated_by_noxious_heat_ L2 - http://www.jneurosci.org/cgi/pmidlookup?view=long&pmid=18829951 DB - PRIME DP - Unbound Medicine ER -