scRNA-sequencing reveals subtype-specific transcriptomic perturbations in DRG neurons ofPirt-EGFPfmice in neuropathic pain condition

Abstract

Functionally distinct subtypes/clusters of dorsal root ganglion (DRG) neurons, which differ in soma size and neurochemical properties, may play different roles in nerve regeneration and pain. However, details about transcriptomic changes in different neuronal subtypes under maladaptive neuropathic pain conditions remain unclear. Chronic constriction injury (CCI) of the sciatic nerve represents a well-established model of neuropathic pain that mimics the etiology of clinical conditions. Therefore, we conducted single-cell RNA-sequencing (scRNA-seq) to characterize subtype-specific perturbations of transcriptomes in lumbar DRG neurons 7 days after sciatic CCI. By using Pirt-EGFPf mice that selectively express enhanced green fluorescent protein in DRG neurons, we established a highly efficient purification process to enrich neurons for scRNA-seq. We observed a loss of marker genes in injured neurons of 12 standard neuronal clusters, and the emergence of four prominent CCI-induced clusters at this peak-maintenance phase of neuropathic pain. Importantly, a portion of injured neurons from a subset of the 12 standard clusters (NP1, PEP5, NF1, and NF2) were spared from injury-induced identity loss, suggesting subtype-specific transcriptomic changes in injured neurons. Moreover, uninjured neurons, which are necessary for mediating the evoked pain, also demonstrated subtype-specific transcriptomic perturbations in these clusters, but not others. Notably, male and female mice showed differential transcriptomic changes in multiple neuronal clusters after CCI, suggesting transcriptomic sexual dimorphism in primary sensory neurons after nerve injury. Collectively, these findings may contribute to the identification of new target genes and development of DRG neuron subtype-specific therapies for optimizing neuropathic pain treatment and nerve regeneration.

Spatial transcriptomics and single-nucleus RNA sequencing reveal a transcriptomic atlas of adult human spinal cord

“…The component heterogeneity of somatosensory neurons in the DRG is essential to relay different peripheral inputs to the central nervous system (Abraira and Ginty, 2013;Gatto et al, 2019;Li et al, 2016;Todd, 2010). The heterogeneity in the molecular transcriptomes, neuronal types, and functional properties of DRG neurons in rodents has been well characterized (Hu et al, 2016;Li et al, 2016;Renthal et al, 2020;Usoskin et al, 2015;Wang et al, 2021a;Zhang et al, 2022;Zhou et al, 2022). Recently, emerging evidence has revealed the organization of human DRG somatosensory neurons (Jung et al, 2023;Nguyen et al, 2021;Tavares-Ferreira et al, 2022;Yu et al, 2023).…”

“…However, we still know little about the interactions between the various neuronal components of the DRG and spinal cord. Wang et al reported that DRG TRPV1 + neuron-spinal ErbB4 + neuron connections are involved in heat sensation and that NRG1-ErbB4 signaling is related to heat hypersensitivity induced by nerve injury (Wang et al, 2022). However, which DRG neuronal types secrete NRG1 remains unclear.…”

Satellite Glial Cells Bridge Sensory Neuron Crosstalk in Visceral Pain and Cross-Organ Sensitization

“…The trans-activation of the uninjured afferents as a result of injury to a subset of neighboring afferents has been observed in several disease settings including post colitis or nerve injury pain (Fukuoka et al, 1998;Traub et al, 1999;Gold, 2000;Gold et al, 2003;Obata et al, 2004;Obata et al, 2006;Qiao and Grider, 2009;Lei and Malykhina, 2012;Tran and Crawford, 2020;Kalpachidou et al, 2022). A recent study using single cell RNAseq of DRG neurons in nerve injury models demonstrates distinct molecular profiles in the injured (Sprr1a + ) and uninjured (Sprr1a -) neurons in the same ganglia (Zhang et al, 2022a). For instance, the injured neurons have reduction of potassium and sodium channels, Calca, Sst and Tac1 expression, while the uninjured neurons have upregulation of Cacna2d1, Tgfb1 and Gal, etc.…”

“…For instance, the injured neurons have reduction of potassium and sodium channels, Calca, Sst and Tac1 expression, while the uninjured neurons have upregulation of Cacna2d1, Tgfb1 and Gal, etc. (Zhang et al, 2022a). The uninjured neurons also contain upregulation of many differentially expressed genes (DEGs) that are related to protein biosynthesis, nerve regeneration and pain (Zhang et al, 2022a).…”

“…(Zhang et al, 2022a). The uninjured neurons also contain upregulation of many differentially expressed genes (DEGs) that are related to protein biosynthesis, nerve regeneration and pain (Zhang et al, 2022a).…”