TRPA1 mediates mechanical currents in the plasma membrane of mouse sensory neurons.
Mechanosensitive channels serve as essential sensors for cells to interact with their environment. The identity of mechanosensitive channels that underlie somatosensory touch transduction is still a mystery. One promising mechanotransduction candidate is the Transient Receptor Potential Ankyrin 1 (TRPA1) ion channel. To determine the role of TRPA1 in the generation of mechanically-sensitive currents, we used dorsal root ganglion (DRG) neuron cultures from adult mice and applied rapid focal mechanical stimulation (indentation) to the soma membrane. Small neurons (diameter <27 microm) were studied because TRPA1 is functionally present in these neurons which largely give rise to C-fiber afferents in vivo. Small neurons were classified by isolectin B4 binding. Mechanically-activated inward currents were classified into two subtypes: Slowly Adapting and Transient. First, significantly more IB4 negative neurons (84%) responded to mechanical stimulation than IB4 positive neurons (54%). Second, 89% of Slowly Adapting currents were present in IB4 negative neurons whereas only 11% were found in IB4 positive neurons. Third, Slowly Adapting currents were completely absent in IB4 negative neurons from TRPA1-/- mice. Consistent with this, Slowly Adapting currents were abolished in wild type IB4 negative neurons stimulated in the presence of a TRPA1 antagonist, HC-030031. In addition, the amplitude of Transient mechanically-activated currents in IB4 positive neurons from TRPA1-/- mice was reduced by over 60% compared to TRPA1+/+ controls; however, a similar reduction did not occur in wild-type neurons treated with HC-030031. Transfection of TRPA1 in HEK293 cells did not significantly alter the proportion or magnitude of mechanically-activated currents in HEK293 cells, indicating that TRPA1 alone is not sufficient to confer mechanical sensitivity.These parallel genetic and pharmacological data demonstrate that TRPA1 mediates the Slowly Adapting mechanically-activated currents in small-diameter IB4 negative neurons from adult mice. The TRPA1 protein may also contribute to a complex that mediates Transient mechanically-activated currents in small IB4 positive C fiber type neurons.
Vilceanu
Daniel
D
Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America.
Stucky
Cheryl L
CL
D000222:Adaptation, Physiological; D000818:Animals; D001696:Biomechanical Phenomena; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D005786:Gene Expression Regulation; D037102:Lectins / Q000172:deficiency / Q000378:metabolism; D008297:Male; D051379:Mice; D011984:Sensory Receptor Cells / Q000166:cytology* / Q000378:metabolism*; D000074025:TRPA1 Cation Channel; D013997:Time Factors; D050051:Transient Receptor Potential Channels / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
D037102:Lectins; D000074025:TRPA1 Cation Channel; D050051:Transient Receptor Potential Channels; C475685:Trpa1 protein, mouse
Pharmacol Ther. 2009 Sep;123(3):371-85
19501617
J Biol Chem. 2007 May 4;282(18):13180-9
17353192
Neuron. 2006 Apr 20;50(2):277-89
16630838
J Physiol. 2006 Dec 15;577(Pt 3):815-28
17038434
Nature. 2004 Jan 15;427(6971):260-5
14712238
Mol Pain. 2009 Apr 21;5:19
19383149
Nat Rev Mol Cell Biol. 2009 Jan;10(1):44-52
19197331
J Neurosci. 1999 Aug 1;19(15):6497-505
10414978
J Physiol. 2007 Aug 15;583(Pt 1):175-93
17584831
Structure. 2005 Apr;13(4):669-82
15837205
J Biol Chem. 1999 Mar 12;274(11):7325-33
10066796
Mol Pain. 2006 Aug 21;2:28
16923187
Nat Rev Neurosci. 2007 Jul;8(7):510-21
17585304
Physiol Rev. 2008 Oct;88(4):1449-90
18923187
J Neurosci. 2009 Apr 15;29(15):4808-19
19369549
Neurosci Lett. 1999 Oct 8;273(3):179-82
10515188
Nat Neurosci. 2007 Mar;10(3):277-9
17259981
Neurosci Lett. 2008 Jun 20;438(2):221-7
18456404
Cell. 2003 Mar 21;112(6):819-29
12654248
J Neurosci. 2002 Jun 15;22(12):RC228
12045233
J Pain. 2010 Jun;11(6):588-99
20015699
J Invest Dermatol. 2009 Sep;129(9):2312-5
19282836
Eur J Neurosci. 2009 Apr;29(8):1568-78
19419422
Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15959-64
14671322
J Neurophysiol. 2003 Jan;89(1):513-24
12522198
Curr Opin Neurobiol. 2009 Aug;19(4):362-9
19683913
EMBO J. 2009 May 20;28(10):1479-91
19322198
Neuropharmacology. 2009 Jun;56(8):1138-46
19348834
Proc Natl Acad Sci U S A. 2007 Aug 14;104(33):13525-30
17686976
Curr Opin Neurobiol. 2005 Aug;15(4):397-405
16006117
Nature. 2004 Dec 9;432(7018):723-30
15483558