Anti-TRPV2 (aa 744-761) polyclonal antibody

Immunohistochemistry for the transient receptor, potential cation channel subfamily V member 1 (TRPV1) and 2 (TRPV2) was performed on the stellate ganglion and spinal cord in human cadavers. In the stellate ganglion, 25.3% and 16.2% of sympathetic neurons contained TRPV1- and TRPV2-immunoreactivity, respectively. The cell size analysis also demonstrated that proportion of TRPV1- or TRPV2-immunoreactive (-IR) neurons among large (>600 mu m(2)) sympathetic neurons (TRPV1, 30.7%; TRPV2, 27.0%) was higher than among small (<600 mu m(2)) sympathetic neurons (TRPV1, 22.0%; TRPV2, 13.6%). The present study also demonstrated that 10.0% of sympathetic neurons in the stellate ganglion had pericellular TRPV2-IR nerve fibers. Fourteen percent of large neurons and 7.8% of small neurons were surrounded by TRPV2-IR nerve fibers. TRPV2-immunoreactivity was also detected in about 40% of neuronal cell bodies with pericellular TRPV2-IR nerve fibers. In the lateral horn of the human thoracic spinal cord, TRPV2-immunoreactivity was expressed by some neurons and many varicose fibers surrounding TRPV2-immunonegative neurons. TRPV2-IR pericellular fibers in the stellate ganglion may originate from the lateral horn of the spinal cord. There appears to be TRPV1- or TRPV2-IR sympathetic pathway in the human stellate ganglion and spinal cord. (C) 2015 Elsevier Ireland Ltd. All rights reserved.

Multimodal gating is an essential feature of many TRP ion channels, enabling them to respond to complex cellular environments. TRPV1, a pain receptor involved in nociception at the peripheral nerve terminals, can be activated by a range of physical and chemical stimuli ( e. g., capsaicin, proton, and heat) and further sensitized by proinflammatory substances. How a single receptor achieves this multiplicity of functionality is poorly understood at the molecular level. Here, we investigated the structural basis of proton activation of TRPV1. Chimeric channels between rTRPV1 and the low pH-insensitive homolog TRPV2 were constructed by systematically exchanging the extracellular domains and were characterized using whole-cell recording in transiently transfected HEK293 cells. Two discrete domains, one involving the pore helix and the other the S3-S4 linker, were found crucial for direct activation of the channel by low pH. Single residue mutations in either domain (T633A/V538L) abrogated the proton-evoked current while preserving the capsaicin and heat responses and their potentiation by mildly acidic pH. Both residues exert a gating effect through hydrophobic interactions. Our results unravel novel information on the structural basis of channel function, and support the existence of discrete domains for multimodal gating of the channel. In view of the resemblance of the pore of TRPV1 to KcsA, our findings also provide evidence on the pore helix as an active component in channel gating in addition to its role in ion permeation.