An integrative approach to the facile functional classification of dorsal root ganglion neuronal subclasses
- 10 March 2020
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 117 (10), 5494-5501
- https://doi.org/10.1073/pnas.1911382117
Abstract
Somatosensory neurons have historically been classified by a variety of approaches, including structural, anatomical, and genetic markers; electrophysiological properties; pharmacological sensitivities; and more recently, transcriptional profile differentiation. These methodologies, used separately, have yielded inconsistent classification schemes. Here, we describe phenotypic differences in response to pharmacological agents as measured by changes in cytosolic calcium concentration for the rapid classification of neurons in vitro; further analysis with genetic markers, whole-cell recordings, and single-cell transcriptomics validated these findings in a functional context. Using this general approach, which we refer to as tripartite constellation analysis (TCA), we focused on large-diameter dorsal-root ganglion (L-DRG) neurons with myelinated axons. Divergent responses to the K-channel antagonist, KM-conopeptide RIIIJ (RIIIJ), reliably identified six discrete functional cell classes. In two neuronal subclasses (L1 and U), block with RIIIJ led to an increase in [Ca](i). Simultaneous electrophysiology and calcium imaging showed that the RIIIJ-elicited increase in [Ca](i), corresponded to different patterns of action potentials (APs), a train of APs in L1 neurons, and sporadic firing in L2 neurons. Genetically labeled mice established that L1 neurons are proprioceptors. The single-cell transcriptomes of L1 and L2 neurons showed that L2 neurons are A delta-low-threshold mechanoreceptors. RIIIJ effects were replicated by application of the K(v)1.1 selective antagonist, Dendrotoxin-K, in several L-DRG subclasses (L1, L2, L3, and L5), suggesting the presence of functional K(v)1.1/K(v)1.2 heteromeric channels. Using this approach on other neuronal subclasses should ultimately accelerate the comprehensive classification and characterization of individual somatosensory neuronal subclasses within a mixed population.Keywords
Funding Information
- U.S. Department of Defense (PR161686)
- HHS | NIH | National Institute of General Medical Sciences (GM48677)
This publication has 24 references indexed in Scilit:
- Classifying neuronal subclasses of the cerebellum through constellation pharmacologyJournal of Neurophysiology, 2016
- Constellation Pharmacology: A New Paradigm for Drug DiscoveryAnnual Review of Pharmacology and Toxicology, 2015
- Defining modulatory inputs into CNS neuronal subclasses by functional pharmacological profilingProceedings of the National Academy of Sciences of the United States of America, 2014
- Using constellation pharmacology to define comprehensively a somatosensory neuronal subclassProceedings of the National Academy of Sciences of the United States of America, 2014
- Characterization of two neuronal subclasses through constellation pharmacologyProceedings of the National Academy of Sciences of the United States of America, 2012
- Functional profiling of neurons through cellular neuropharmacologyProceedings of the National Academy of Sciences of the United States of America, 2012
- Biochemical Characterization of κM-RIIIJ, a Kv1.2 Channel BlockerJournal of Biological Chemistry, 2010
- Distinct potassium channels on pain-sensing neuronsProceedings of the National Academy of Sciences of the United States of America, 2001
- Identification of residues in dendrotoxin K responsible for its discrimination between neuronal K+channels containing Kv1.1 and 1.2 α subunitsJBIC Journal of Biological Inorganic Chemistry, 1999
- Novel effects of dendrotoxin homologues on subtypes of mammalian Kv1 potassium channels expressed in Xenopus oocytesFEBS Letters, 1996