Biology subjects

Del Rosario, J. S.

Publications and source records attributed to Del Rosario, J. S..

8 recordsLinked to original sources

bioRxiv2025

Human sensory neurons exhibit cell-type-specific, pain-associated differences in intrinsic excitability and expression of SCN9A and SCN10A

Despite major advances in pain science, the approval of novel therapeutics has been slow. A major cause for the lack of new analgesics may be fundamental biological differences between humans and model organisms used in preclinical research. Large-scale transcriptional profiling efforts on human dorsal root ganglia (hDRG) have now identified at least 22 distinct neuronal subtypes; however, a significant knowledge gap exists in ascribing functional phenotypes to these diverse neuronal populations. In this study, we use Patch-seq recordings in hDRG to link electrical properties to transcriptionally defined cell types. First, through unbiased clustering of electrophysiological properties from 228 hDRG neurons, we identify three electrophysiological subtypes (E-types). Next, we show that E-types can be mapped onto specific transcriptional classes (T-types) of hDRG neurons. We find that donors pain history is associated with E-type-specific differences in electrical properties, some of which may be associated with higher expression of voltage-gated sodium channels, NaV1.7 and NaV1.8. These results highlight the importance of using multimodal profiling to better understand human sensory neuron biology and may help reveal novel therapeutic targets driving chronic pain. TeaserMapping electrical properties to transcriptional profiles of human sensory neurons offers new insights into pain neurobiology

neuroscience↗

bioRxiv2025

Expression of Fibroblast Growth Factor Receptor 3 (FGFR3) in the Human Peripheral Nervous System: Implications for the Putative Pathogenic Role of FGFR3 Autoantibodies in Neuropathy

IntroductionAutoantibodies to the Fibroblast Growth Factor Receptor 3 (FGFR3-AAbs) have been associated with idiopathic sensory-predominant neuropathy. The pathogenicity of FGFR3-AAbs in this disorder is unknown. Pathogenic mechanisms of autoantibodies in other dysimmune neuropathies commonly involve their direct binding to antigens on either neurons or glia. The expression of FGFR3 in the human peripheral nervous system is unknown. Therefore, as an initial step toward clarifying the pathogenicity of FGFR3-AAbs, we characterized the expression of FGFR3 in nerve (hNerve), dorsal root ganglia (hDRG) and spinal cord (hSC) in human. MethodsFGFR3 mRNA was assayed via in situ hybridization (ISH) on post-mortem sections of hNerve, hDRG and hSC, and by re-analysis of RNA-sequencing data from hDRG. FGFR3 protein was assayed in these tissues using capillary electrophoretic immunoassays (CEIA) with several validated anti-FGFR3 antibodies. ResultsFGFR3 mRNA was not detected in hNerve or hDRG but was abundant in hSC by ISH. FGFR3 protein was absent from hNerve and hDRG by CEIA but was moderately expressed in hSC. DiscussionA direct pathogenic mechanism of FGFR3-AAbs in sensory neuropathy would require the expression of FGFR3 in either neurons or non-neuronal cells in nerve or DRG. Using multiple methods, we did not detect FGFR3 expression at the mRNA or protein levels in these tissues. Given the absence of FGFR3 from hNerve and hDRG, it is improbable that FGFR3-AAbs cause direct damage to the neural components involved in neuropathy and thus are unlikely to be pathogenic, although indirect mechanisms via non-neural cells cannot be excluded.

neuroscience↗

bioRxiv2023

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.

neuroscience↗

bioRxiv2023

Intrinsic Homeostatic Plasticity in Mouse and Human Sensory Neurons

In response to changes in activity induced by environmental cues, neurons in the central nervous system undergo homeostatic plasticity to sustain overall network function during abrupt changes in synaptic strengths. Homeostatic plasticity involves changes in synaptic scaling and regulation of intrinsic excitability. Increases in spontaneous firing and excitability of sensory neurons are evident in some forms of chronic pain in animal models and human patients. However, whether mechanisms of homeostatic plasticity are engaged in sensory neurons under normal conditions or altered after chronic pain is unknown. Here, we showed that sustained depolarization induced by 30mM KCl induces a compensatory decrease in the excitability in mouse and human sensory neurons. Moreover, voltage-gated sodium currents are robustly reduced in mouse sensory neurons contributing to the overall decrease in neuronal excitability. Decreased efficacy of these homeostatic mechanisms could potentially contribute to the development of the pathophysiology of chronic pain.

neuroscience↗

bioRxiv2023

Bradykinin receptor expression and bradykinin-mediated sensitization of human sensory neurons

Bradykinin is a peptide implicated in inflammatory pain in both humans and rodents. In rodent sensory neurons, activation of B1 and B2 bradykinin receptors induces neuronal hyperexcitability. Recent evidence suggests that human and rodent dorsal root ganglia (DRG), which contain the cell bodies of sensory neurons, differ in the expression and function of key GPCRs and ion channels; whether BK receptor expression and function are conserved across species has not been studied in depth. In this study, we used human DRG tissue from organ donors to provide a detailed characterization of bradykinin receptor expression and bradykinin-induced changes in the excitability of human sensory neurons. We found that B2 and, to a lesser extent, B1 receptors are expressed by human DRG neurons and satellite glial cells. B2 receptors were enriched in the nociceptor subpopulation. Using patch-clamp electrophysiology, we found that acute bradykinin increases the excitability of human sensory neurons, while prolonged exposure to bradykinin decreases neuronal excitability in a subpopulation of human DRG neurons. Finally, our analyses suggest that donors history of chronic pain and age may be predictors of higher B1 receptor expression in human DRG neurons. Together, these results indicate that acute BK-induced hyperexcitability, first identified in rodents, is conserved in humans and provide further evidence supporting BK signaling as a potential therapeutic target for treating pain in humans.

neuroscience↗

bioRxiv2021

TMEM120A/TACAN inhibits mechanically activated Piezo2 channels

Mechanically activated Piezo2 channels are key mediators of light touch and proprioception in mice and humans. Relatively little is known about what other proteins regulate Piezo2 activity in a cellular context. TACAN (TMEM120A) was proposed to act as a high threshold mechanically activated ion channel in nociceptive dorsal root ganglion (DRG) neurons. Here we find that TACAN co-expression robustly reduced mechanically activated Piezo2 currents, but did not inhibit mechanically activated Piezo1 and TREK1 currents. TACAN co-expression did not affect cell surface expression of either Piezo1 or Piezo2 and did not have major effects on the cortical actin or tubulin cytoskeleton. TACAN expression alone did not result in the appearance of mechanically activated currents above background. In addition, TACAN and Piezo2 expression in DRG neurons overlapped, and siRNA mediated knockdown of TACAN did not decrease the proportion of slowly adapting mechanically activated currents, but resulted in an increased proportion of rapidly adapting currents. Our data do not support TACAN being a mechanically activated ion channel, and identify it as a negative modulator of Piezo2 channel activity.

neuroscience↗

bioRxiv2020

A Piezo1 open state reveals a multi-fenestrated ion permeation pathway

Force-sensing Piezo channels are essential to many aspects of vertebrate physiology. Activation of Piezo1 is facilitated by the presence of negative membrane lipids in the inner leaflet, such as phosphatidylinositol-4,5-bisphosphate (PIP2). Here, to study how Piezo1 opens, we performed molecular dynamics simulations of Piezo1 in membranes flattened by the periodic boundary effect and with or without PIP2 lipids. The Piezo1 pore spontaneously opens in the asymmetrical bilayer but not in the symmetric membrane or when PIP2 lipids are neutralized. Electrophysiological characterization of putative PIP2-interacting Piezo1 residues suggests the contribution of multiple PIP2 binding sites. Our Piezo1 open state recapitulates ionic selectivity, unitary conductance and mutant phenotypes obtained from numerous experimental studies. Tracking ion diffusion through the open pore reveals the presence of intracellular and extracellular fenestrations, delineating a multi-fenestrated permeation pathway. This open state sheds light on the mechanisms of lipid modulation, permeation, and selectivity in a Piezo channel.

biophysics↗

bioRxiv2019

Gi-Coupled Receptor Activation Potentiates Piezo2 Currents via Gβγ

SUMMARYDysregulation of mechanosensitive Piezo2 channels is a hallmark of mechanical allodynia, yet the cellular mechanisms that sensitize mechanoreceptors are still poorly understood. Activation of Gi-coupled receptors sensitizes Piezo2 currents, but whether Gi-coupled receptors regulate the activity of Piezo2 channels is not known. Here, we found that activation of Gi-coupled receptors potentiates Piezo2 currents in dorsal root ganglion (DRG) neurons and in heterologous systems, but inhibits Piezo1 currents in heterologous systems. The potentiation, or inhibition of Piezo currents is abolished when blocking G{beta}{gamma} with the c-terminal domain of the beta-adrenergic kinase ({beta}ARKct). Pharmacological inhibition of kinases downstream of G{beta}{gamma}, phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK), also abolished the potentiation of Piezo2 currents. Hence, our studies illustrate an indirect mechanism of action of G{beta}{gamma} to sensitize Piezo2 currents after activation of Gi-coupled receptors.

neuroscience↗