Epigenomic profiling of mouse nucleus accumbens at single-cell resolution.

The nucleus accumbens (NAc) is a key brain region involved in reward processing and is linked to multiple neuropsychiatric conditions such as substance use disorder, depression, and chronic pain. Recent studies have begun to investigate NAc gene expression at a single-cell resolution, however, our understanding of the cellular heterogeneity of the NAc epigenomic landscape remains limited. In this study, we utilize single-nucleus assay for transposase-accessible chromatin using sequencing (snATAC-seq) to map cell-type-specific differences in chromatin accessibility in the NAc. Our findings not only reveal the transcription factors and putative gene regulatory elements that may contribute to these cell-type-specific epigenomic differences but also provide a valuable resource for future studies investigating epigenomic changes that occur in neuropsychiatric disorders.

Projection-TAGs enable multiplex projection tracing and multi-modal profiling of projection neurons.

Single-cell multiomic techniques have sparked immense interest in developing a comprehensive multi-modal map of diverse neuronal cell types and their brain wide projections. However, investigating the spatial organization, transcriptional and epigenetic landscapes of brain wide projection neurons is hampered by the lack of efficient and easily adoptable tools. Here we introduce Projection-TAGs, a retrograde AAV platform that allows multiplex tagging of projection neurons using RNA barcodes. By using Projection-TAGs, we performed multiplex projection tracing of the mouse cortex and high-throughput single-cell profiling of the transcriptional and epigenetic landscapes of the cortical projection neurons. Projection-TAGs can be leveraged to obtain a snapshot of activity-dependent recruitment of distinct projection neurons and their molecular features in the context of a specific stimulus. Given its flexibility, usability, and compatibility, we envision that Projection-TAGs can be readily applied to build a comprehensive multi-modal map of brain neuronal cell types and their projections.

Transcriptomic landscape of mammalian ventral pallidum at single-cell resolution.

The ventral pallidum (VP) is critical for motivated behaviors. While contemporary work has begun to elucidate the functional diversity of VP neurons, the molecular heterogeneity underlying this functional diversity remains incompletely understood. We used snRNA-seq and in situ hybridization to define the transcriptional taxonomy of VP cell types in mice, macaques, and baboons. We found transcriptional conservation between all three species, within the broader neurochemical cell types. Unique dopaminoceptive and cholinergic subclusters were identified and conserved across both primate species but had no homolog in mice. This harmonized consensus VP cellular atlas will pave the way for understanding the structure and function of the VP and identified key neuropeptides, neurotransmitters, and neuro receptors that could be targeted within specific VP cell types for functional investigations.

Harmonized cross-species cell atlases of trigeminal and dorsal root ganglia.

Sensory neurons in the dorsal root ganglion (DRG) and trigeminal ganglion (TG) are specialized to detect and transduce diverse environmental stimuli to the central nervous system. Single-cell RNA sequencing has provided insights into the diversity of sensory ganglia cell types in rodents, nonhuman primates, and humans, but it remains difficult to compare cell types across studies and species. We thus constructed harmonized atlases of the DRG and TG that describe and facilitate comparison of 18 neuronal and 11 non-neuronal cell types across six species and 31 datasets. We then performed single-cell/nucleus RNA sequencing of DRG from both human and the highly regenerative axolotl and found that the harmonized atlas also improves cell type annotation, particularly of sparse neuronal subtypes. We observed that the transcriptomes of sensory neuron subtypes are broadly similar across vertebrates, but the expression of functionally important neuropeptides and channels can vary notably. The resources presented here can guide future studies in comparative transcriptomics, simplify cell-type nomenclature differences across studies, and help prioritize targets for future analgesic development.

Harmonized cross-species cell atlases of trigeminal and dorsal root ganglia.

Peripheral sensory neurons in the dorsal root ganglion (DRG) and trigeminal ganglion (TG) are specialized to detect and transduce diverse environmental stimuli including touch, temperature, and pain to the central nervous system. Recent advances in single-cell RNA-sequencing (scRNA-seq) have provided new insights into the diversity of sensory ganglia cell types in rodents, non-human primates, and humans, but it remains difficult to compare transcriptomically defined cell types across studies and species. Here, we built cross-species harmonized atlases of DRG and TG cell types that describe 18 neuronal and 11 non-neuronal cell types across 6 species and 19 studies. We then demonstrate the utility of this harmonized reference atlas by using it to annotate newly profiled DRG nuclei/cells from both human and the highly regenerative axolotl. We observe that the transcriptomic profiles of sensory neuron subtypes are broadly similar across vertebrates, but the expression of functionally important neuropeptides and channels can vary notably. The new resources and data presented here can guide future studies in comparative transcriptomics, simplify cell type nomenclature differences across studies, and help prioritize targets for future pain therapy development.

Profiling the molecular signature of satellite glial cells at the single cell level reveals high similarities between rodents and humans.

ABSTRACT: Peripheral sensory neurons located in dorsal root ganglia relay sensory information from the peripheral tissue to the brain. Satellite glial cells (SGCs) are unique glial cells that form an envelope completely surrounding each sensory neuron soma. This organization allows for close bidirectional communication between the neuron and its surrounding glial coat. Morphological and molecular changes in SGC have been observed in multiple pathological conditions such as inflammation, chemotherapy-induced neuropathy, viral infection, and nerve injuries. There is evidence that changes in SGC contribute to chronic pain by augmenting the neuronal activity in various rodent pain models. Satellite glial cells also play a critical role in axon regeneration. Whether findings made in rodent model systems are relevant to human physiology have not been investigated. Here, we present a detailed characterization of the transcriptional profile of SGC in mice, rats, and humans at the single cell level. Our findings suggest that key features of SGC in rodent models are conserved in humans. Our study provides the potential to leverage rodent SGC properties and identify potential targets in humans for the treatment of nerve injuries and alleviation of painful conditions.

Sensory neurons display cell-type-specific vulnerability to loss of neuron-glia interactions.

Peripheral nervous system (PNS) injuries initiate transcriptional changes in glial cells and sensory neurons that promote axonal regeneration. While the factors that initiate the transcriptional changes in glial cells are well characterized, the full range of stimuli that initiate the response of sensory neurons remain elusive. Here, using a genetic model of glial cell ablation, we find that glial cell loss results in transient PNS demyelination without overt axonal loss. By profiling sensory ganglia at single-cell resolution, we show that glial cell loss induces a transcriptional injury response preferentially in proprioceptive and Aß RA-LTMR neurons. The transcriptional response of sensory neurons to mechanical injury has been assumed to be a cell-autonomous response. By identifying a similar response in non-injured, demyelinated neurons, our study suggests that this represents a non-cell-autonomous transcriptional response of sensory neurons to glial cell loss and demyelination.

Human and mouse trigeminal ganglia cell atlas implicates multiple cell types in migraine.

Sensitization of trigeminal ganglion neurons contributes to primary headache disorders such as migraine, but the specific neuronal and non-neuronal trigeminal subtypes that are involved remain unclear. We thus developed a cell atlas in which human and mouse trigeminal ganglia are transcriptionally and epigenomically profiled at single-cell resolution. These data describe evolutionarily conserved and human-specific gene expression patterns within each trigeminal ganglion cell type, as well as the transcription factors and gene regulatory elements that contribute to cell-type-specific gene expression. We then leveraged these data to identify trigeminal ganglion cell types that are implicated both by human genetic variation associated with migraine and two mouse models of headache. This trigeminal ganglion cell atlas improves our understanding of the cell types, genes, and epigenomic features involved in headache pathophysiology and establishes a rich resource of cell-type-specific molecular features to guide the development of more selective treatments for headache and facial pain.

Ionic liquid functionalized 3D graphene-carbon nanotubes‒AuPd nanoparticles‒molecularly imprinted copolymer based paracetamol electrochemical sensor: Preparation, characterization and application.

An innovative electrochemical sensor for paracetamol (PCM) determination was fabricated by electropolymerization imprinting on three-dimension (3D) AuPd nanoparticles‒ionic liquid (IL) functionalized graphene‒carbon nanotubes nanocomposite (AuPd/GN-CNTs-IL) modified glassy carbon electrode. The GN-CNTs supported AuPd alloy nanoparticles were prepared via one-pot hydrothermal method in the presence of IL (i.e. 1-hydroxyethyl-3-methyl imidazolium bis[(trifluoromethyl) sulfonyl] imide), which not only promoted the formation of small AuPd alloy nanoparticles, but also acted as "spacer" to prevent the π-π stacking and aggregation of graphene sheets and carbon nanotubes. The resulting composite had large surface area and high electrocatalysis. The PCM imprinted poly(carbazole-co-pyrrole) exhibited good recognition to PCM and had high stability. Based on the synergic effect of PCM imprinted copolymer and 3D AuPd/GN-CNTs-IL nanocomposite, a highly selective and sensitive electrochemical sensor was established. It presented a good linear relationship from 0.10 to 10 µM with a low limit of detection of 50 nM (S/N = 3). The sensor could be applied to the detection of PCM in biological samples, with acceptable recoveries (84.5%-102%). In addition, it was successfully used to monitor the concentration of PCM in urine from a patient with fever cold.

Isolation of Nuclei from Mouse Dorsal Root Ganglia for Single-nucleus Genomics.

Primary somatosensory neurons, whose cell bodies reside in the dorsal root ganglion (DRG) and trigeminal ganglion, are specialized to transmit sensory information from the periphery to the central nervous system. Our molecular understanding of peripheral sensory neurons has been limited by both their heterogeneity and low abundance compared with non-neuronal cell types in sensory ganglia. We describe a protocol to isolate nuclei from mouse DRGs using iodixanol density gradient centrifugation, which enriches for neuronal nuclei while still sampling non-neuronal cells such as satellite glia and Schwann cells. This protocol is compatible with a range of downstream applications such as single-nucleus transcriptional and epigenomic assays.

Transcriptional Reprogramming of Distinct Peripheral Sensory Neuron Subtypes after Axonal Injury.

Primary somatosensory neurons are specialized to transmit specific types of sensory information through differences in cell size, myelination, and the expression of distinct receptors and ion channels, which together define their transcriptional and functional identity. By profiling sensory ganglia at single-cell resolution, we find that all somatosensory neuronal subtypes undergo a similar transcriptional response to peripheral nerve injury that both promotes axonal regeneration and suppresses cell identity. This transcriptional reprogramming, which is not observed in non-neuronal cells, resolves over a similar time course as target reinnervation and is associated with the restoration of original cell identity. Injury-induced transcriptional reprogramming requires ATF3, a transcription factor that is induced rapidly after injury and necessary for axonal regeneration and functional recovery. Our findings suggest that transcription factors induced early after peripheral nerve injury confer the cellular plasticity required for sensory neurons to transform into a regenerative state.

One-step solution synthesis of a two-dimensional semiconducting covalent organometallic nanosheet via the condensation of boronic acid.

In this work, a 2D covalent organometallic nanosheet (COMS) was designed and successfully synthesized through the one-step conjunction of a terpyridine-metal-terpyridine (TMT) sandwich coordinate motif with borate ester covalent heterocyclic (B3O3) linkage via the condensation of boronic acid. The obtained 2D COMS with a cobalt coordination center (2D COMS-Co) showed promising p-type semiconducting properties.

Facile preparation of molecularly imprinted polypyrrole-graphene-multiwalled carbon nanotubes composite film modified electrode for rutin sensing.

In this paper, a novel molecularly imprinted composite film modified electrode was presented for rutin (RT) detection. The modified electrode was fabricated by electropolymerization of pyrrole on a graphene-multiwalled carbon nanotubes composite (G-MWCNTs) coated glassy carbon electrode in the presence of RT. The netlike G-MWCNTs composite, prepared by in situ hydrothermal process, had high conductivity and electrocatalytic activity. At the resulting MIP/G-MWCNTs/GCE electrode RT could produce a sensitive anodic peak in pH 1.87 Britton-Robinson buffer solution. The factors affecting the electrochemical behavior and response of RT on the modified electrode were carefully investigated and optimized. Under the selected conditions, the linear response range of RT was 0.01-1.0µmolL-1 and the detection limit (S/N=3) was 5.0nmolL-1. The electrode was successfully applied to the determination of RT in buckwheat tea and orange juice samples, and the recoveries for standards added were 93.4-105%.