Functional and molecular insights into muscle proprioceptors
- Department of Neuroscience, Karolinska Institutet, Sweden
- Laboratory of Neurobiology of Pain & Therapeutics, Department of Neuroscience, Karolinska Institutet, Sweden
Figures
Figure 1
Overview of the dorsal root ganglia (DRG) muscle proprioceptive system.
(A) Examples of behavior that rely on muscle proprioceptive feedback for proper execution. (B) Partial schematic representation of the ascending proprio-brainstem pathways through the external cuneate nucleus (ECu) and supporting skilled forelimb behavior; the question marks indicate putative pathway. (C) Incomplete circuit diagram of the proprioceptive-CNS network for movement control, showing local connections with interneurons (not shown), and emphasizing the ECu as a key processing hub for supraspinal proprioceptive feedback. The schematic also illustrates the peripheral terminations of proprioceptive neurons (PNs) within skeletal muscles and highlights the classic, distinct subtypes of PNs. Abbreviations: Cu, cuneate nucleus; GTO, Golgi tendon organ; MS, muscle spindle.
Box 1—figure 1
A comprehensive atlas of proprioceptive neuron (PN) cell types and their associated functional features.
(A) Uniform Manifold Approximation and Projection (UMAP) visualization of single-cell transcriptomes of PNs from Wu et al. dataset, colored by cell type. Below: representation of the soma sizes of the subtypes proportional to the average soma sizes of the respective PN subtypes observed in situ, from Wu et al. Right: dot plot summarizing the rostro-caudal distribution of PN subtypes in dorsal root ganglia (DRG), as in Wu et al. (shown as averages; C: cervical C2; B: brachial C5-8; T: thoracic T1/4/10; L: lumbar L2-5). The size of the circle reflects the percentage of different subtypes among all PNs in each region. The color intensity reflects how a subtype is distributed along the rostro-caudal axis, where 1 represents its highest representation. (B) Integration of PN sc/snRNAseq datasets. Left: UMAP of an integrated PNs atlas derived from eight distinct datasets. Right: bar graph depicting the datasets contribution to the integrated atlas (see Materials and methods). (C) Heatmap showing marker gene expression for cell types in the integrated PNs atlas. (D) Stacked violin plot showing the expression of sensory neuron operational components across PN cell types, based on the Wu et al. dataset.
Figure 2 with 1 supplement
Key molecular markers defining the functional properties of proprioceptive neuron (PN) subtypes.
This schematic shows representative genes central to the core functions of proprioceptive neurons (PNs), including sensory transduction, axonal conduction, and synaptic transmission. The selected markers are pivotal for neuronal functionality and were chosen for their high and specific expression. Font size is directly proportional to gene expression levels, normalized within each functional category to the most highly expressed gene. Functional categories are separated by white lines. The size of the circle next to each PN subtype name reflects its relative somatic diameter as observed in vivo (Wu et al., 2021).
Figure 2—figure supplement 1
Corresponding cell types between datasets.
(A) Uniform Manifold Approximation and Projection (UMAP) plot of proprioceptive neurons (PNs) from Oliver et al. with Wu et al. nomenclature. NA: non-assigned. (*) This cluster is identified as II3-PNs after subclustering and cluster assignment; cells of this cluster do not express marker genes of the Ib population. (B) Stacked violin plot of cell-type probability scores of cells from Oliver et al. predicted as Wu et al. cell types. (C) Sankey plot representing the cluster and cell correspondence from Oliver et al. to Wu et al. nomenclatures.
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Functional and molecular insights into muscle proprioceptors
eLife 14:e106803.
https://doi.org/10.7554/eLife.106803
