Cross-species transcriptomic atlas of dorsal root ganglia reveals species-specific programs for sensory function

Abstract

Sensory neurons of the dorsal root ganglion (DRG) are critical for maintaining tissue homeostasis by sensing and initiating responses to stimuli. While most preclinical studies of DRGs are conducted in rodents, much less is known about the mechanisms of sensory perception in primates. We generated a transcriptome atlas of mouse, guinea pig, cynomolgus monkey, and human DRGs by implementing a common laboratory workflow and multiple data-integration approaches to generate high-resolution cross-species mappings of sensory neuron subtypes. Using our atlas, we identified conserved core modules highlighting subtype-specific biological processes related to inflammatory response. We also identified divergent expression of key genes involved in DRG function, suggesting species-specific adaptations specifically in nociceptors that likely point to divergent function of nociceptors. Among these, we validated that TAFA4, a member of the druggable genome, was expressed in distinct populations of DRG neurons across species, highlighting species-specific programs that are critical for therapeutic development.

Single-Soma Deep RNA Sequencing of Human Dorsal Root Ganglion Neurons Reveals Novel Molecular and Cellular Mechanisms Underlying Somatosensation

“…The copyright holder for this preprint this version posted March 18, 2023. ; https://doi.org/10. 1101/2023 In this study, we sequenced over 1000 DRG neurons from 6 DRGs at the thoracic (T11-T12) and lumbar (L2-L5) levels of three healthy Caucasian human donors, with ~150 to 200 neurons per DRG, which represent 1-2% of the total neurons within a human DRG. Thus, it is necessary to sequence more neurons for a reliable representation.…”

“…Different single-cell RNA-seq approaches, including single-nucleus RNA-seq 21, 23, 86 , spatial transcriptomics 22 , and our LCM-based single soma RNA-seq, have generated four datasets of transcriptome profiles and cell type clusters of human DRG neurons. These datasets and results overlap to some extent but also exhibit some obvious differences (an example shown in Fig.…”

“…Moreover, human DRG/TG neuronal somas are much larger than those of non-neuronal cells, so they are prone to damage by enzyme digestion and mechanical forces during single-cell isolation. Due to these difficulties, single-nucleus RNA-seq and spatial transcriptomics have been employed for human DRG/TG neurons 21–23 . Despite novel insights from these studies, the quantity of transcripts in the nucleus is much lower than those in the soma, and the nuclear transcripts may not represent the full transcriptome profile of the whole cell 24 , while commercially available spatial transcriptomics lack single-neuron resolution.…”

A dual role of microbiota type 17 immunity in tissue repair and pain

“…Moreover, recent transcriptomic analysis of mouse dorsal root ganglia sensory neurons has demonstrated a much wider diversity of sensory neuron subclasses than originally thought 14 . An even more recent study by Jung and colleagues highlighted multiple differences between mouse and human sensory neurons with a species‐specific transcriptomic atlas 15 . At the protein level, the dichotomy of nociceptor subclasses as peptidergic or nonpeptidergic previously described in mice and highlighted in the Enamorado et al .…”

“…14 An even more recent study by Jung and colleagues highlighted multiple differences between mouse and human sensory neurons with a species-specific transcriptomic atlas. 15 At the protein level, the dichotomy of nociceptor subclasses as peptidergic or nonpeptidergic previously described in mice and highlighted in the Enamorado et al's study is not apparent in humans where dorsal root ganglia sensory neurons and spinal cord dorsal horn projections express markers for both subclasses. 16 Another major challenge with clinical translation of rodent immunological research is the multiple species differences in immune cell subsets and therefore different markers used between mice and humans, and as such researchers need to be careful to avoid overstating the clinical importance of studies in mice.…”