title: Piezo2 Expression in Mechanosensitive Dental Primary Afferent Neurons.
abstract: Mechanosensitive ion channels have been suggested to be expressed in dental primary afferent (DPA) neurons to transduce the movement of dentinal fluid since the proposal of hydrodynamic theory. Piezo2, a mechanosensitive, rapidly inactivating (RI) ion channel, has been recently identified in dorsal root ganglion (DRG) neurons to mediate tactile transduction. Here, we examined the expression of Piezo2 in DPA neurons by in situ hybridization, single-cell reverse transcriptase polymerase chain reaction, and whole-cell patch-clamp recordings. DPA neurons with Piezo2 messenger RNA (mRNA) or Piezo2-like currents were further characterized based on their neurochemical and electrophysiological properties. Piezo2 mRNA was found mostly in medium- to large-sized DPA neurons, with the majority of these neurons also positive for Nav1.8, CGRP, and NF200, whereas only a minor population was positive for IB4and peripherin. Whole-cell patch-clamp recordings revealed Piezo2-like, RI currents evoked by mechanical stimulation in a subpopulation of DPA neurons. RI currents were pharmacologically blocked by ruthenium red, a compound known to block Piezo2, and were also reduced by small interfering RNA-mediated Piezo2 knockdown. Piezo2-like currents were observed almost exclusively in IB4-negative DPA neurons, with the current amplitude larger in capsaicin-insensitive DPA neurons than the capsaicin-sensitive population. Our findings show that subpopulation of DPA neurons is indeed mechanically sensitive. Within this subpopulation of mechanosensitive DPA neurons, we have identified the Piezo2 ion channel as a potential transducer for mechanical stimuli, contributing to RI inward currents. Piezo2-positive DPA neurons were characterized as medium- to large-sized neurons with myelinated A-fibers, containing nociceptive peptidergic neurotransmitters.
authors.affiliation: 1 Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea.
authors.forename: J
authors.initials: J
authors.lastname: Won
authors.affiliation: 2 Dental Research Institute and Department of Neurobiology & Physiology, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: H
authors.initials: H
authors.lastname: Vang
authors.affiliation: 1 Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea.
authors.forename: P R
authors.initials: PR
authors.lastname: Lee
authors.affiliation: 2 Dental Research Institute and Department of Neurobiology & Physiology, School of Dentistry, Seoul National University, Seoul, Republic of Korea.|3 Department of Physiology, College of Medicine, Gachon University, Incheon, Republic of Korea (present address).
authors.forename: Y H
authors.initials: YH
authors.lastname: Kim
authors.affiliation: 1 Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea.
authors.forename: H W
authors.initials: HW
authors.lastname: Kim
authors.affiliation: 2 Dental Research Institute and Department of Neurobiology & Physiology, School of Dentistry, Seoul National University, Seoul, Republic of Korea.|4 Department of Neuroscience and Oral Physiology, Osaka University Graduate School of Dentistry, Osaka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kang
authors.affiliation: 1 Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea.|2 Dental Research Institute and Department of Neurobiology & Physiology, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: S B
authors.initials: SB
authors.lastname: Oh
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D005727:Ganglia, Spinal / Q000166:cytology; D017403:In Situ Hybridization; D007473:Ion Channels / Q000378:metabolism*; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009475:Neurons, Afferent / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012430:Ruthenium Red / Q000494:pharmacology
chemical_list: D007473:Ion Channels; C000589204:piezo2 protein, rat; D012430:Ruthenium Red
keywords: electrophysiology; mechanotransduction; molecular biology; neuroscience/neurobiology; pulp biology; sensory neurons