Members of the CUGBP Elav-like family of RNA-binding proteins are expressed in distinct populations of primary sensory neurons.

Primary sensory dorsal root ganglia (DRG) neurons are diverse, with distinct populations that respond to specific stimuli. Previously, we observed that functionally distinct populations of DRG neurons express mRNA transcript variants with different 3' untranslated regions (3'UTRs). 3'UTRs harbor binding sites for interaction with RNA-binding proteins (RBPs) for transporting mRNAs to subcellular domains, modulating transcript stability, and regulating the rate of translation.

Regulation of Mitochondrial Function by Epac2 Contributes to Acute Inflammatory Hyperalgesia.

G-coupled receptors signaling through cAMP provide a key mechanism for the sensitization of nociceptive sensory neurons, and the cAMP effector Epac has been implicated in the transition from acute to chronic pain. Epac exerts its effects through Rap1 and protein kinase C (PKC). To identify targets of Epac-PKC signaling in sensory neurons of the mouse dorsal root ganglion (DRG), we profiled PKC substrate proteins phosphorylated in response to the activation of Epac with the proinflammatory prostaglandin E2 (PGE2).

A Novel Mechanism for Zika Virus Host-Cell Binding.

Zika virus (ZIKV) recently emerged in the Western Hemisphere with previously unrecognized or unreported clinical presentations. Here, we identify two putative binding mechanisms of ancestral and emergent ZIKV strains featuring the envelope (E) protein residue asparagine 154 (ASN154) and viral phosphatidylserine (PS). Synthetic peptides representing the region containing ASN154 from strains PRVABC59 (Puerto Rico 2015) and MR_766 (Uganda 1947) were exposed to neuronal cells and fibroblasts to model ZIKV E protein/cell interactions and bound MDCK or Vero cells and primary neurons significantly.

Phospho-substrate profiling of Epac-dependent protein kinase C activity.

Exchange protein directly activated by cAMP (Epac) and protein kinase A are effectors for cAMP with distinct actions and regulatory mechanisms. Epac is a Rap guanine nucleotide exchange factor that activates Rap1; protein kinase C (PKC) is a major downstream target of Epac-Rap1 signaling that has been implicated in a variety of pathophysiological processes, including cardiac hypertrophy, cancer, and nociceptor sensitization leading to chronic pain. Despite the implication of both Epac and PKC in these processes, few downstream targets of Epac-PKC signaling have been identified.

Deletion of the murine ATP/UTP receptor P2Y2 alters mechanical and thermal response properties in polymodal cutaneous afferents.

P2Y2 is a member of the P2Y family of G protein-coupled nucleotide receptors that is widely co-expressed with TRPV1 in peripheral sensory neurons of the dorsal root ganglia. To characterize P2Y2 function in cutaneous afferents, intracellular recordings from mouse sensory neurons were made using an ex vivo preparation in which hindlimb skin, saphenous nerve, dorsal root ganglia and spinal cord are dissected intact. The peripheral response properties of individual cutaneous C-fibers were analyzed using digitally controlled mechanical and thermal stimuli in male P2Y2(+/+) and P2Y2(-/-) mice.

Neurturin overexpression in skin enhances expression of TRPM8 in cutaneous sensory neurons and leads to behavioral sensitivity to cool and menthol.

Neurturin (NRTN) is a member of the glial cell line-derived neurotrophic factor family of ligands that exerts its actions via Ret tyrosine kinase and GFRα2. Expression of the Ret-GFRα2 coreceptor complex is primarily restricted to the peripheral nervous system and is selectively expressed by sensory neurons that bind the isolectin B(4) (IB(4)). To determine how target-derived NRTN affects sensory neuron properties, transgenic mice that overexpress NRTN in keratinocytes (NRTN-OE mice) were analyzed.

Phenotypic switching of nonpeptidergic cutaneous sensory neurons following peripheral nerve injury.

In adult mammals, the phenotype of half of all pain-sensing (nociceptive) sensory neurons is tonically modulated by growth factors in the glial cell line-derived neurotrophic factor (GDNF) family that includes GDNF, artemin (ARTN) and neurturin (NRTN). Each family member binds a distinct GFRα family co-receptor, such that GDNF, NRTN and ARTN bind GFRα1, -α2, and -α3, respectively. Previous studies revealed transcriptional regulation of all three receptors in following axotomy, possibly in response to changes in growth factor availability.

Purinergic receptor P2Y1 regulates polymodal C-fiber thermal thresholds and sensory neuron phenotypic switching during peripheral inflammation.

We have recently found that, following complete Freund's adjuvant (CFA)-induced inflammation, cutaneous polymodal nociceptors (CPM) lacking the transient receptor potential vanilloid 1 (TRPV1) are sensitized to heat stimuli. In order to determine possible mechanisms playing a role in this change, we examined gene expression in the L2/L3 sensory ganglia following CFA injection into the hairy hind paw skin and found that G-protein-coupled purinoreceptor P2Y1 expression was increased. This receptor is of particular interest, as most CPMs innervating mouse hairy skin bind isolectin B4, which co-localizes with P2Y1.

The ADP receptor P2Y1 is necessary for normal thermal sensitivity in cutaneous polymodal nociceptors.

Background: P2Y1 is a member of the P2Y family of G protein-coupled nucleotide receptors expressed in peripheral sensory neurons. Using ratiometric calcium imaging of isolated dorsal root ganglion neurons, we found that the majority of neurons responding to adenosine diphosphate, the preferred endogenous ligand, bound the lectin IB4 and expressed the ATP-gated ion channel P2X3. These neurons represent the majority of epidermal afferents in hairy skin, and are predominantly C-fiber polymodal nociceptors (CPMs), responding to mechanical stimulation, heat and in some cases cold.

Gi- and Gq-coupled ADP (P2Y) receptors act in opposition to modulate nociceptive signaling and inflammatory pain behavior.

Background: Investigations of nucleotide signaling in nociception to date have focused on actions of adenosine triphosphate (ATP). Both ATP-gated ion channels (P2X receptors) and G protein-coupled (P2Y) receptors contribute to nociceptive signaling in peripheral sensory neurons. In addition, several studies have implicated the Gq-coupled adenosine diphosphate (ADP) receptor P2Y1 in sensory transduction.

The P2Y2 receptor sensitizes mouse bladder sensory neurons and facilitates purinergic currents.

Sensitization of bladder afferents is an underlying contributor to the development and maintenance of painful bladder syndrome/interstitial cystitis. Extracellular purines and pyrimidines (e.g.

In search of analgesia: emerging roles of GPCRs in pain.

Of all clinically marketed drugs, greater than thirty percent are modulators of G protein-coupled receptors (GPCRs). Nearly 400 GPCRs (i.e.

Thermal nociception and TRPV1 function are attenuated in mice lacking the nucleotide receptor P2Y2.

Recent studies indicate that ATP and UTP act at G protein-coupled (P2Y) nucleotide receptors to excite nociceptive sensory neurons; nucleotides also potentiate signaling through the pro-nociceptive capsaicin receptor, TRPV1. We demonstrate here that P2Y(2) is the principal UTP receptor in somatosensory neurons: P2Y(2) is highly expressed in dorsal root ganglia and P2Y(2)-/- mice showed profound deficits in UTP-evoked calcium transients and potentiation of capsaicin responses. P2Y(2)-/- mice were also deficient in the detection of painful heat: baseline thermal response latencies were increased and mutant mice failed to develop thermal hypersensitivity in response to inflammatory injury (injection of complete Freund's adjuvant into the hindpaw).

Production of dissociated sensory neuron cultures and considerations for their use in studying neuronal function and plasticity.

Dissociated primary sensory neurons are commonly used to study growth factor-dependent cell survival, axon outgrowth, differentiation and basic mechanisms of sensory physiology and pain. Spinal or trigeminal sensory neurons can be collected from embryos, neonates or adults, treated with enzymes that degrade the extracellular matrix, triturated and grown in defined media with or without growth factors and additional animal sera. Production of cultures can take as little as 2.

Glial cell line-derived neurotrophic factor family members sensitize nociceptors in vitro and produce thermal hyperalgesia in vivo.

Nerve growth factor (NGF) has been implicated as an effector of inflammatory pain because it sensitizes primary afferents to noxious thermal, mechanical, and chemical [e.g., capsaicin, a transient receptor potential vanilloid receptor 1 (TRPV1) agonist] stimuli and because NGF levels increase during inflammation.

Artemin overexpression in skin enhances expression of TRPV1 and TRPA1 in cutaneous sensory neurons and leads to behavioral sensitivity to heat and cold.

Artemin, a neuronal survival factor in the glial cell line-derived neurotrophic factor family, binds the glycosylphosphatidylinositol-anchored protein GFRalpha3 and the receptor tyrosine kinase Ret. Expression of the GFRalpha3 receptor is primarily restricted to the peripheral nervous system and is found in a subpopulation of nociceptive sensory neurons of the dorsal root ganglia (DRGs) that coexpress the Ret and TrkA receptor tyrosine kinases and the thermosensitive channel TRPV1. To determine how artemin affects sensory neuron properties, transgenic mice that overexpress artemin in skin keratinocytes (ART-OE mice) were analyzed.

ASIC3, an acid-sensing ion channel, is expressed in metaboreceptive sensory neurons.

Background: ASIC3, the most sensitive of the acid-sensing ion channels, depolarizes certain rat sensory neurons when lactic acid appears in the extracellular medium. Two functions have been proposed for it: 1) ASIC3 might trigger ischemic pain in heart and muscle; 2) it might contribute to some forms of touch mechanosensation. Here, we used immunocytochemistry, retrograde labelling, and electrophysiology to ask whether the distribution of ASIC3 in rat sensory neurons is consistent with either of these hypotheses.

Overexpression of NGF or GDNF alters transcriptional plasticity evoked by inflammation.

Transcriptional changes evoked in nociceptive sensory neurons by inflammatory injury play a substantial role in the generation of and recovery from painful hypersensitivity. Transgenic mice overexpressing nerve growth factor (NGF) or glial cell line-derived neurotrophic factor (GDNF) in the skin possess a greatly increased number of nociceptors. Surprisingly, NGF-overexpressers display reduced hypersensitivity and recovered more rapidly in response to inflammation, suggesting a compensatory suppression of nociceptive transmission in these mice.

The P2Y agonist UTP activates cutaneous afferent fibers.

The majority of adenosine triphosphate (ATP)-induced nociceptive transduction and pain has been attributed to ionotropic P2X3 receptors. Metabotropic P2Y receptors, some of which bind pyrimidines as well as purines, have received little attention. Here we have examined the ability of P2Y receptor signaling to evoke action potential firing in functionally identified afferent fibers using the skin nerve preparation from adult mouse.

Transgenic mice possessing increased numbers of nociceptors do not exhibit increased behavioral sensitivity in models of inflammatory and neuropathic pain.

At least two classes of neciceptors can be distinguished based on their growth factor requirements: glial cell-line derived neurotrophic factor (GDNF)- and nerve growth factor (NGF)-dependent primary afferent neurons. Based on numerous anatomical and biochemical differences, GDNF- and NGF-dependent neurons have been proposed to be involved in the development of different types of persistent pain. To examine this hypothesis we used two lines of transgenic mice that contained a supernormal number of either NGF- or GDNF-dependent neurons (referred to as NGF-OE and GDNF-OE mice, respectively).

ATP and UTP excite sensory neurons and induce CREB phosphorylation through the metabotropic receptor, P2Y2.

Extracellular ATP rapidly excites nociceptive sensory neurons by opening ATP-gated ion channels (P2X receptors). Here, we describe two actions of both ATP and UTP on rat sensory neurons that are relatively slow and sustained: phosphorylation of the transcription factor CREB and delayed action potential firing that persists for tens of seconds after removal of the ligand. The pharmacology of these responses indicates that they are mediated by the metabotropic receptor P2Y2, and not by P2X receptors.