Biology subjects

Millet, Q.

Publications and source records attributed to Millet, Q..

7 recordsLinked to original sources

bioRxiv2022

Transcriptomic and proteomic profiling of NaV1.8-expressing mouse nociceptors

Nociceptors play an essential role in both acute pain and chronic pain conditions. and have recently been classified into distinct subsets using single-cell transcriptional profiling. In this study, we examined protein levels in dorsal root ganglia using DIA Mass-spectrometry technologies with NaV1.8Cre+/-; ROSA26-flox-stop-flox-DTA (Diphtheria toxin fragment A) mutant mice (NaV1.8Cre-DTA), in which NaV1.8-expressing neurons (mainly nociceptors) in dorsal root ganglia (DRG) were ablated. The results show that 353 transcripts and 78 proteins, including nociceptor-specific sodium channels NaV1.8 (Scn10a) and NaV1.9 (Scn11a), were specifically expressed in nociceptors of DRG. A comparative analysis revealed that about 40% of nociceptor-specific proteins are shared within the nociceptor-specific transcript dataset. Scatter plots show that the proteome and transcriptome datasets in nociceptors have a moderate correlation (r = 0.4825), indicating the existence of post-transcriptional and post-translational gene regulation in nociceptors. This combined profiling study provides a unique resource for sensory studies, especially for pain research.

neuroscience↗

bioRxiv2020

Silent cold-sensing neurons drive cold allodynia in neuropathic pain states

Neuropathic pain patients often experience innocuous cooling as excruciating pain. The cell and molecular basis of this cold allodynia is little understood. We used in vivo calcium imaging of sensory ganglia to investigate the activity of peripheral cold-sensing neurons in three mouse models of neuropathic pain: oxaliplatin-induced neuropathy, partial sciatic nerve ligation and ciguatera poisoning. In control mice, cold-sensing neurons were few in number and small in size. In neuropathic animals with cold allodynia, a set of normally silent large-diameter neurons became sensitive to cooling. Many silent cold-sensing neurons expressed the nociceptor markers NaV1.8 and CGRP. Ablating these neurons diminished cold allodynia. Blocking KV1 voltage-gated potassium channels was sufficient to trigger de novo cold sensitivity in silent cold-sensing neurons. Thus silent cold-sensing neurons are unmasked in diverse neuropathic pain states and cold allodynia results from peripheral sensitization caused by altered nociceptor excitability. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/073999v1_ufig1.gif" ALT="Figure 1"> View larger version (60K): org.highwire.dtl.DTLVardef@e3aeforg.highwire.dtl.DTLVardef@3f40bdorg.highwire.dtl.DTLVardef@b344baorg.highwire.dtl.DTLVardef@16540ef_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2019

Sensory neuron-derived Nav1.7 contributes to dorsal horn neuron excitability

Expression of the voltage-gated sodium channel Nav1.7 in sensory neurons is required for pain sensation. We examined the role of Nav1.7 in the dorsal horn of the spinal cord using an epitope-tagged knock-in mouse. Immuno-electron microscopy showed the presence of Nav1.7 in dendrites of lamina II neurons, despite the absence of mRNA. Peripheral nervous system-specific Nav1.7 KO mice showed central deficits with lamina II dorsal horn tonic firing neurons more than halved and single spiking neurons more than doubled. Nav1.7 blocker PF05089771 diminished excitability in dorsal horn neurons, but had no effect on Nav1.7 KO mice. These data demonstrate an unsuspected functional role of peripherally generated Nav1.7 in dorsal horn neurons and an expression pattern that would not be predicted by transcriptomic analysis.

neuroscience↗

bioRxiv2018

Analgesia linked to Nav1.7 loss of function requires mu and delta opioid receptors

Functional deletion of the SCN9A gene encoding sodium channel Nav1.7 makes humans and mice pain-free (1,2). Opioid signaling contributes to this analgesic state (3). Here we show that the pharmacological block or deletion of both and {delta} opioid receptors is required to abolish Nav1.7 null opioid-related analgesia.{kappa}-opioid receptor antagonists were without effect. Enkephalins encoded by the Penk gene are upregulated in Nav1.7 nulls (3). Deleting Nfat5, a transcription factor with binding motifs upstream of Penk (4), induces the same level of enkephalin mRNA expression as found in Nav1.7 nulls, but without consequent analgesia. These data confirm that a combination of events linked to SCN9A gene loss is required for analgesia. Higher levels of endogenous enkephalins (3), potentiated opioid receptors (5), diminished electrical excitability (6,7) and loss of neurotransmitter release (2,1) together contribute to the analgesic phenotype found in Nav1.7 null mouse and human mutants. These observations help explain the failure of Nav1.7 channel blockers alone to produce analgesia and suggest new routes for analgesic drug development.

neuroscience↗

bioRxiv2017

Regulation of somatosensory mechanotransduction by Annexin A6

Sensory neuron mechanically-activated slowly adapting currents have been linked to noxious mechanosensation. We identified a Conotoxin, Noxious Mechanosensation Blocker -1, that blocks such currents selectively and inhibits mechanical pain Using an active biotinylated form of the toxin we identified 67 binding proteins in sensory neurons and sensory neuron-derived cell lines using mass spectrometry. Annexin A6 was the most frequently identified binding protein. Annexin A6 knockout mice showed an enhanced sensitivity to mechanical stimuli. An increase in rapidly adapting currents was observed in sensory neurons alongside a decrease in slowly adapting currents. Conversely, overexpression of Annexin A6 in sensory neurons inhibited rapidly adapting currents and augmented slowly adapting currents. Furthermore, co-expression of Annexin A6 with Piezo2 led to an inhibition of Piezo-mediated rapidly adapting currents. AAV-mediated overexpression of Annexin A6 in sensory neurons attenuated mechanical pain in a mouse model of osteoarthritis. These data demonstrate a modulatory role for Annexin A6 in somatosensory mechanotransduction.

neuroscience↗

bioRxiv2017

Brain-derived neurotrophic factor derived from peripheral sensory neurons plays a critical role in pain chronification

Multiple studies support the pro-nociceptive role of brain-derived neurotrophin factor (BDNF) in pain processes in the peripheral and central nervous system. We have previously shown that nociceptor-derived BDNF is implicated in inflammatory pain. Microglial-derived BDNF has also been shown to be involved in neuropathic pain. However, the distinct contribution of primary afferent-derived BNDF to chronic pain processing remains undetermined. In this study, we used Advillin-CreERT2 mice to delete Bdnf from all adult peripheral sensory neurons. Conditional BDNF knockouts were healthy with no sensory neuron loss. Behavioural assays and in vivo electrophysiology indicated that spinal excitability was normal. Following formalin inflammation or neuropathy with a modified Chung model, we observed normal development of acute pain behaviour, but a deficit in second phase formalin-induced nocifensive responses and a reversal of neuropathy-induced mechanical hypersensitivity during the later chronic pain phase in conditional BDNF knockout mice. In contrast, we observed normal development of acute and chronic neuropathic pain in the Seltzer model, indicating differences in the contribution of BDNF to distinct models of neuropathy. We further used a model of hyperalgesic priming to examine the contribution of primary afferent-derived BDNF in the transition from acute to chronic pain, and found that primed BDNF knockout mice do not develop prolonged mechanical hypersensitivity. Our data suggest that BDNF derived from sensory neurons plays a critical role in mediating the transition from acute to chronic pain.

neuroscience↗

bioRxiv2017

Mapping protein interactions of sodium channel NaV1.7 using epitope-tagged gene targeted mice

The voltage-gated sodium channel NaV1.7 plays a critical role in pain pathways. Besides action potential propagation, NaV1.7 regulates neurotransmitter release, integrates depolarizing inputs over long periods and regulates transcription. In order to better understand these functions, we generated an epitope-tagged NaV1.7 mouse that showed normal pain behavior. Analysis of NaV1.7 complexes affinity-purified under native conditions by mass spectrometry revealed 267 NaV1.7 associated proteins including known interactors, such as the sodium channel {beta}3 subunit (Scn3b) and collapsin response mediator protein (Crmp2), and novel interactors. Selected novel NaV1.7 protein interactors membrane-trafficking protein synapototagmin-2 (Syt2), G protein-regulated inducer of neurite outgrowth 1 (Gprin1), L-type amino acid transporter 1 (Lat1) and transmembrane P24 trafficking protein 10 (Tmed10) together with Scn3b and Crmp2 were validated using co-immunoprecipitation and functional assays. The information provided with this physiologically normal epitope-tagged mouse should provide useful insights into the pain mechanisms associated with NaV1.7 channel function.

neuroscience↗