Transcriptional profiling of thermo-sensitive mouse DRG neurons in healthy and neuropathic conditions

Resumen del póster presentado al International Workshop on Chronic Pain and Itch: Mechanisms and Circuits, celebrado en Alicante (España) del 20 al 22 de octubre de 2021.Most transduction mechanisms for detecting cold environment changes depending on the ion channel's transient receptor melastatin 8 (TRPM8). TRPM8 expressing neurons constitute a well-characterized small population of primary sensory neurons, which detect innocuous cooling and mostly lack nociceptive markers. Although transcriptomic studies have recently identified different molecular TRPM8(+) neurons, they fail to correlate with cold-sensitive neurons' proprieties studied functionally over decades. Imaging calcium experiments have described at least two thermosensory populations; low- and high-threshold cold receptors involved in innocuous or pain cold transduction, respectively. Additionally, it is still unknown whether other mechanisms are implicated in cold sensation apart from the TRPM8 ion channel. To address this question, we used fluorescence-activated cell sorting (FACS) in a transgenic mouse line expressing EYFP under the TRPM8 promoter to purify and sequence TRPM8-expressing DRG neurons in healthy and neuropathic conditions. To compare the transcriptome of TRPM8(+) expressing neurons, we also isolated and sequenced the nonpeptidergic IB4(+) population with high expression of TRPA1 and no overlap with TRPM8. We also compare our RNA-Seq data with recent scRNA-Seq studies in the somatosensory system. After validation using RNAscope, we have molecularly identified a subset of peptidergic TRPM8(+). These neurons express lower levels of TRPM8, coherent with a lower sensitivity to cold and cooling compounds (e.g. menthol and WS-12). Moreover, the genetic alterations obtained after oxaliplatin-induced peripheral neuropathy suggest their contribution to the development of cold hypersensitivity during neuropathic conditions.Supported by Ministerio de Ciencia e Innovación, PID2019-108194RB-100 co-financed by the European Regional Development Fund (ERDF), the “Severo Ochoa” Program for Centers of Excellence in R&D SEV-2017-0723 and a predoctoral fellowship BES-2014-070394.Peer reviewe