Price, Theodore J.
Permanent URI for this collectionhttps://hdl.handle.net/10735.1/4097
Theodore Price is an Associate Professor of Neuroscience. He is alos the head of the Pain Neurobiology Research Group. "Our laboratory is interested in the fundamental principles underlying pain plasticity. Our goal is to develop novel therapeutics based on these discoveries with the potential to either prevent the development of or permanently reverse chronic pain states. We focus on two major areas: 1) plasticity in peripheral nociceptive neurons following injury and, 2) plasticity in central nervous system circuits that results from persistent stimulation of peripheral nociceptors. We utilize molecular, biochemical, genetic, behavioral and electrophysiological techniques combined with an overarching interest in pharmacology and drug discovery to tackle this problem."
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Item Nociceptor Translational Profiling Reveals the Ragulator-Rag GTPase Complex as a Critical Generator of Neuropathic Pain(Soc Neuroscience, 2019-01-16) Megat, Salim; Ray, Pradipta R.; Moy, Jamie K.; Lou, Tzu-Fang; Barragan-Iglesias, Paulino; Li, Yan; Pradhan, Grishma; Wanghzou, Andi; Ahmad, Ayesha; Burton, Michael D.; North, Robert Y.; Dougherty, Patrick M.; Khoutorsky, Arkady; Sonenberg, Nahum; Webster, Nevin R.; Dussor, Gregory; Campbell, Zachary T.; Price, Theodore J.; 0000-0003-4281-3985 (Pradhan, G); 0000-0002-0628-824X (Burton, MD); 0000-0002-3768-6996 (Campbell, ZT); 0000-0002-6971-6221 (Price, TJ); Megat, Salim; Ray, Pradipta R.; Moy, Jamie K.; Lou, Tzu-Fang; Barragan-Iglesias, Paulino; Pradhan, Grishma; Wanghzou, Andi; Ahmad, Ayesha; Burton, Michael D.; Dussor, Gregory; Campbell, Zachary T.; Price, Theodore J.Nociceptors, sensory neurons in the DRG that detect damaging or potentially damaging stimuli, are key drivers of neuropathic pain. Injury to these neurons causes activation of translation regulation signaling, including the mechanistic target of rapamycin complex 1 (mTORC1) and mitogen-activated protein kinase interacting kinase(MNK) eukaryotic initiation factor (eIF) 4E pathways. This is a mechanism driving changes in excitability of nociceptors that is critical for the generation of chronic pain states; however, the mRNAs that are translated to lead to this plasticity have not been elucidated. To address this gap in knowledge, we used translating ribosome affinity purification in male and female mice to comprehensively characterize mRNA translation in Scn10a-positive nociceptors in chemotherapy-induced neuropathic pain (CIPN) caused by paclitaxel treatment. This unbiased method creates a new resource for the field, confirms many findings in the CIPN literature and also find extensive evidence for new target mechanisms that may cause CIPN. We provide evidence that an underlying mechanism of CIPN is sustained mTORC1 activation driven by MNK1-eIF4E signaling. RagA, aGTPase controlling mTORC1 activity, is identified as a novel target of MNK1-eIF4E signaling. This demonstrates a novel translation regulation signaling circuit wherein MNK1-eIF4E activity drives mTORC1 via control of RagA translation. CIPN and RagA translation are strongly attenuated by genetic ablation of eIF4E phosphorylation, MNK1 elimination or treatment with the MNK inhibitor eFT508. We identify a novel translational circuit for the genesis of neuropathic pain caused by chemotherapy with important implications for therapeutics.Item Emerging Neurotechnology for Antinoceptive Mechanisms and Therapeutics Discovery(Elsevier Advanced Technology, 2018-11-13) Black, Bryan J.; Atmaramani, Rahul; Plagens, Sarah; Campbell, Zachary T.; Dussor, Gregory; Price, Theodore J.; Pancrazio, Joseph J.; 0000-0002-3768-6996 (Campbell, ZT); 0000-0002-6971-6221 (Price, TJ); 0000-0001-8276-3690 (Pancrazio, JJ); Black, Bryan J.; Atmaramani, Rahul; Plagens, Sarah; Campbell, Zachary T.; Dussor, Gregory; Price, Theodore J.; Pancrazio, Joseph J.The tolerance, abuse, and potential exacerbation associated with classical chronic pain medications such as opioids creates a need for alternative therapeutics. Phenotypic screening provides a complementary approach to traditional target-based drug discovery. Profiling cellular phenotypes enables quantification of physiologically relevant traits central to a disease pathology without prior identification of a specific drug target. For complex disorders such as chronic pain, which likely involves many molecular targets, this approach may identify novel treatments. Sensory neurons, termed nociceptors, are derived from dorsal root ganglia (DRG) and can undergo changes in membrane excitability during chronic pain. In this review, we describe phenotypic screening paradigms that make use of nociceptor electrophysiology. The purpose of this paper is to review the bioelectrical behavior of DRG neurons, signaling complexity in sensory neurons, various sensory neuron models, assays for bioelectrical behavior, and emerging efforts to leverage microfabrication and microfluidics for assay development. We discuss limitations and advantages of these various approaches and offer perspectives on opportunities for future development.Item The Antidiabetic Drug Metformin Prevents and Reverses Neuropathic Pain and Spinal Cord Microglial Activation in Male but not Female Mice(Academic Press Ltd- Elsevier Science Ltd, 2018-11-01) Inyang, Kufreobong E.; Szabo-Pardi, Thomas; Wentworth, Emma; McDougal, Timothy A.; Dussor, Gregory; Burton, Michael D.; Price, Theodore J.; 0000-0002-6971-6221 (Price, TJ); Dussor, Gregory; Price, Theodore J.; Inyang, Kufreobong E.; Szabo-Pardi, Thomas; Wentworth, Emma; McDougal, Timothy A.Metformin is a widely prescribed drug used in the treatment of type II diabetes. While the drug has many mechanisms of action, most of these converge on AMP activated protein kinase (AMPK), which metformin activates. AMPK is a multifunctional kinase that is a negative regulator of mechanistic target of rapamycin (mTOR) and mitogen activated protein kinase (MAPK) signaling. Activation of AMPK decreases the excitability of dorsal root ganglion neurons and AMPK activators are effective in reducing chronic pain in inflammatory, post-surgical and neuropathic rodent models. We have previously shown that metformin leads to an enduring resolution of neuropathic pain in the spared nerve injury (SNI) model in male mice and rats. The precise mechanism underlying this long-lasting effect is not known. We conducted experiments to investigate the effects of metformin on SNI-induced microglial activation, a process implicated in the maintenance of neuropathic pain that has recently been shown to be sexually dimorphic. We find that metformin is effective at inhibiting development of neuropathic pain when treatment is given around the time of injury and that metformin is likewise effective at reversing neuropathic mechanical hypersensitivity when treatment is initiation weeks after injury. This effect is linked to decreased Iba-1 staining in the dorsal horn, a marker of microglial activation. Importantly, these positive behavioral and microglia effects of metformin were only observed in male mice. We conclude that the neuropathic pain modifying effects of metformin are sex-specific supporting a differential role for microglial activation in male and female mice.Item Activation of the Integrated Stress Response in Nociceptors Drives Methylglyoxal-Induced Pain(Lippincott Williams & Wilkins, 2019-01) Barragan-Iglesias, Paulino; Kuhn, Jasper; Vidal-Cantu, Guadalupe C.; Belen Salinas-Abarca, Ana; Granados-Soto, Vinicio; Dussor, Gregory; Campbell, Zachary T.; Price, Theodore J.; 0000-0002-3768-6996 (Campbell, ZT); 0000-0002-6971-6221 (Price, TJ); Dussor, Gregory; Campbell, Zachary T.; Price, Theodore J.Methylglyoxal (MGO) is a reactive glycolytic metabolite associated with painful diabetic neuropathy at plasma concentrations between 500 nM and 5 μM. The mechanisms through which MGO causes neuropathic pain at these pathological concentrations are not known. Because MGO has been linked to diabetic neuropathic pain, which is prevalent and poorly treated, insight into this unsolved biomedical problem could lead to much needed therapeutics. Our experiments provide compelling evidence that ~ 1-μM concentrations of MGO activate the integrated stress response (ISR) in IB4-positive nociceptors in the dorsal root ganglion (DRG) of mice in vivo and in vitro. Blocking the integrated stress response with a specific inhibitor (ISRIB) strongly attenuates and reverses MGO-evoked pain. Moreover, ISRIB reduces neuropathic pain induced by diabetes in both mice and rats. Our work elucidates the mechanism of action of MGO in the production of pain at pathophysiologically relevant concentrations and suggests a new pharmacological avenue for the treatment of diabetic and other types of MGO-driven neuropathic pain.Item Protease Activated Receptor 2 (PAR2) Activation Causes Migraine-Like Pain Behaviors in Mice(Sage Publications Ltd, 2018-05-31) Hassler, Shayne N.; Ahmad, Fatima B.; Burgos-Vega, Carolina C.; Boitano, Scott; Vagner, Josef; Price, Theodore J.; Dussor, Gregory; 0000-0002-6971-6221 (Price, TJ); Hassler, Shayne N.; Ahmad, Fatima B.; Burgos-Vega, Carolina C.; Price, Theodore J.; Dussor, GregoryBackground Pain is the most debilitating symptom of migraine. The cause of migraine pain likely requires activation of meningeal nociceptors. Mast cell degranulation, with subsequent meningeal nociceptor activation, has been implicated in migraine pathophysiology. Degranulating mast cells release serine proteases that can cleave and activate protease activated receptors. The purpose of these studies was to investigate whether protease activated receptor 2 is a potential generator of nociceptive input from the meninges by using selective pharmacological agents and knockout mice. Methods Ratiometric Ca⁺⁺ imaging was performed on primary trigeminal and dural cell cultures after application of 2at-LIGRL-NH₂, a specific protease activated receptor 2 agonist. Cutaneous hypersensitivity and facial grimace was measured in wild-type and protease activated receptor 2⁻ᐟ⁻ mice after dural application of 2at-LIGRL-NH₂ or compound 48-80, a mast cell degranulator. Behavioral experiments were also conducted in mice after dural application of 2at-LIGRL-NH₂ (2AT) in the presence of either C391, a selective protease activated receptor 2 antagonist, or sumatriptan. Results 2at-LIGRL-NH₂ evoked Ca²⁺ signaling in mouse trigeminal neurons, dural fibroblasts and in meningeal afferents. Dural application of 2at-LIGRL-NH₂ or 48-80 caused dose-dependent grimace behavior and mechanical allodynia that were attenuated by either local or systemic application of C391 as well as in protease activated receptor 2⁻ᐟ⁻ mice. Nociceptive behavior after dural injection of 2at-LIGRL-NH₂ was also attenuated by sumatriptan. Conclusions Functional protease activated receptor 2 receptors are expressed on both dural afferents and fibroblasts and activation of dural protease activated receptor 2 produces migraine-like behavioral responses. Protease activated receptor 2 may link resident immune cells to meningeal nociceptor activation, driving migraine-like pain and implicating protease activated receptor 2 as a therapeutic target for migraine in humans.Item Non-Invasive Dural Stimulation in Mice: A Novel Preclinical Model of Migraine(Sage Publications Ltd, 2018-05-31) Burgos-Vega, Carolina Christina; Quigley, Lilyana D.; dos Santos, Gabriela Trevisan; Yan, Flora; Asiedu, Marina; Jacobs, Blaine; Motina, Marina; Safdar, Nida; Yousuf, Hayyan; Avona, Amanda; Price, Theodore J.; Dussor, Greg; Burgos-Vega, Carolina Christina; Quigley, Lilyana D.; Yan, Flora; Asiedu, Marina; Jacobs, Blaine; Motina, Marina; Safdar, Nida; Yousuf, Hayyan; Avona, Amanda; Price, Theodore J.; Dussor, GregBackground Migraine is characterized by a collection of neurological symptoms in the absence of injury or damage. However, several common preclinical migraine models require significant damage to the skull to stimulate the dura mater, the likely source of afferent signaling leading to head pain. The goal of this study was to determine whether dural stimulation can be performed in mice using an injection that does not cause injury or damage. Methods Using mice, injections of stimuli were administered to the dura mater through the soft tissue at the intersection between the lambdoidal and sagittal sutures. This technique did not require a permanent cannula nor did it cause damage to the skull or dura. Following injection of noxious stimuli, migraine-like behaviors were measured including cutaneous allodynia and facial grimace. The retrograde tracer fluorogold was applied onto the dura using the same injection technique to label trigeminal ganglion cell bodies, which were then testing in vitro using patch-clamp electrophysiology. Results Dural injection of allyl-isothiocyanate, low pH, interleukin-6, or inflammatory soup but not vehicles, led to cephalic/extracephalic allodynia. Facial grimace responses were also observed with allyl-isothiocyanate, pH 6.0, and interleukin-6. Stimulation with interleukin-6 causes priming to normally subthreshold pH 7.0 stimulation of the dura following resolution of the initial interleukin-6 behavior. Systemic injection of sumatriptan at the time of dural stimulation with inflammatory soup decreased the resulting cutaneous hypersensitivity. Trigeminal ganglion cell bodies retrogradely labeled from the dura had low pH-evoked currents similar to those generated by acid-sensing ion channels. Conclusion Non-invasive dural stimulation in mice can be used as a model of migraine in the absence of injury.Item Dural Calcitonin Gene-Related Peptide Produces Female-Specific Responses in Rodent Migraine Models(Society for Neuroscience, 2019-05-29) Avona, Amanda; Burgos-Vega, Carolina; Burton, Michael D.; Akopian, A. N.; Price, Theodore J.; Dussor, Gregory; 0000-0002-6971-6221 (Price, TJ); 0000-0002-0628-824X (Burton, MD); Avona, Amanda; Burgos-Vega, Carolina; Burton, Michael D.; Price, Theodore J.; Dussor, GregoryMigraine is the second leading cause for disability worldwide and the most common neurological disorder. It is also three times more common in women; reasons for this sex difference are not known. Using preclinical behavioral models of migraine, we show that application of calcitonin gene-related peptide (CGRP) to the rat dura mater produces cutaneous periorbital hypersensitivity. Surprisingly, this response was observed only in females; dural CGRP at doses from 1 pg to 3.8 μg produce no responses in males. In females, dural CGRP causes priming to a pH 7.0 solution after animals recover from the initial CGRP-induced allodynia. Dural application of interleukin-6 causes acute responses in males and females but only causes priming to subthreshold dural CGRP (0.1 pg) in females. Intracisternal application of BDNF also causes similar acute hypersensitivity responses in males and females but only priming to subthreshold dural CGRP (0.1 pg) in females. Females were additionally primed to a subthreshold dose of the NO-donor sodium nitroprusside (0.1 mg/kg) following dural CGRP. Finally, the sexually dimorphic responses to dural CGRP were not specific to rats as similar female-specific hypersensitivity responses were seen in mice, where increased grimace responses were also observed. These data are the first to demonstrate that CGRP-induced headache-like behavioral responses at doses up to 3.8 μg are female-specific both acutely and following central and peripheral priming. These data further implicate dural CGRP signaling in the pathophysiology of migraine and propose a model where dural CGRP-based mechanisms contribute to the sexual disparity of this female-biased disorder.SIGNIFICANCE STATEMENT Calcitonin gene-related peptide (CGRP) has long been implicated in the pathophysiology of migraine, and CGRP-based therapeutics are efficacious for the treatment of migraine in humans. However, the location of action for CGRP in migraine remains unclear. We show here that application of CGRP to the cranial meninges causes behavioral responses consistent with headache in preclinical rodent models. Surprisingly, however, these responses are only observed in females. Acute responses to meningeal CGRP are female-specific and sensitization to CGRP after two distinct stimuli are also female-specific. These data implicate the dura mater as a primary location of action for CGRP in migraine and suggest that female-specific mechanisms downstream of CGRP receptor activation contribute to the higher prevalence of migraine in women. Copyright © 2019 the authors.Item Transcriptome Analysis of the Human Tibial Nerve Identifies Sexually Dimorphic Expression of Genes Involved in Pain, Inflammation, and Neuro-Immunity(Frontiers Media S.A.) Ray, Pradipta R.; Khan, Jawad; Wangzhou, Andi; Tavares-Ferreira, Diana; Akopian, A. N.; Dussor, Gregory; Price, Theodore J.; Ray, Pradipta R.; Khan, Jawad; Wangzhou, Andi; Tavares-Ferreira, Diana; Dussor, Gregory; Price, Theodore J.Sex differences in gene expression are important contributors to normal physiology and mechanisms of disease. This is increasingly apparent in understanding and potentially treating chronic pain where molecular mechanisms driving sex differences in neuronal plasticity are giving new insight into why certain chronic pain disorders preferentially affect women vs. men. Large transcriptomic resources are now available and can be used to mine for sex differences to gather insight from molecular profiles using donor cohorts. We performed in-depth analysis of 248 human tibial nerve (hTN) transcriptomes from the GTEx Consortium project to gain insight into sex-dependent gene expression in the peripheral nervous system (PNS). We discover 149 genes with sex differential gene expression. Many of the more abundant genes in men are associated with inflammation and appear to be primarily expressed by glia or immune cells, with some genes downstream of Notch signaling. In women, we find the differentially expressed transcription factor SP4 that is known to drive a regulatory program, and may impact sex differences in PNS physiology. Many of these 149 differentially expressed (DE) genes have some previous association with chronic pain but few of them have been explored thoroughly. Additionally, using clinical data in the GTEx database, we identify a subset of DE, sexually dimorphic genes in diseases associated with chronic pain: arthritis and Type II diabetes. Our work creates a unique resource that identifies sexually dimorphic gene expression in the human PNS with implications for discovery of sex-specific pain mechanisms. © 2019 Ray, Khan, Wangzhou, Tavares-Ferreira, Akopian, Dussor and Price.Item Spinal Inhibition of P2XR or p38 Signaling Disrupts Hyperalgesic Priming in Male, but not Female, Mice(Elsevier Ltd) Paige, Candler; Maruthy, Gayathri B.; Mejia, Galo; Dussor, Gregory; Price, Theodore J.; 0000 0001 3721 4764 (Dussor, G); 0000-0002-6971-6221 (Price, TJ); Paige, Candler; Maruthy, Gayathri B.; Mejia, Galo; Dussor, Gregory; Price, Theodore J.Recent studies have demonstrated sexual dimorphisms in the mechanisms contributing to the development of chronic pain. Here we tested the hypothesis that microglia might preferentially regulate hyperalgesic priming in male mice. We based this hypothesis on evidence that microglia preferentially contribute to neuropathic pain in male mice via ionotropic purinergic receptor (P2XR) or p38 mitogen-activated protein kinase (p38) signaling. Mice given a single-priming injection of the soluble human interleukin-6 receptor (IL-6r) and then a second injection of prostaglandin E2 (PGE2), which unmasks hyperalgesic priming, shows a significant increase in levels of activated microglia at 3 h following the PGE2 injection in both male and female mice. There was no change in microglia following PGE2. Intrathecal injection of the P2X3/4 inhibitor TNP-ATP blocked the initial response to IL-6r in both males and females, but only blocked hyperalgesic priming in male mice. Intrathecally applied p38 inhibitor, skepinone, had no effect on the initial response to IL-6r but attenuated hyperalgesic priming in males only. Neither TNP-ATP nor skepinone could reverse priming once it had already been established in male mice suggesting that these pathways must be inhibited early in the development of hyperalgesic priming to have an effect. Our work is consistent with previous findings that P2XR and p38 inhibition can lead to male-specific effects on pain behaviors in mice. However, given that we did not observe microglial activation at time points where these drugs were effective, our work also questions whether these effects can be completely attributed to microglia. © 2018 IBROItem Haptic Stroke Testbed for Pharmacological Evaluation of Dynamic Allodynia in Mouse Models(IEEE Computer Society) Lee, Jin; Atwood, Brian J.; Megat, Salim; Dussor, Gregory; Price, Theodore J.; Fey, Ann Majewicz; Lee, Jin; Atwood, Brian J.; Megat, Salim; Dussor, Gregory; Price, Theodore J.; Fey, Ann MajewiczDynamic mechanical allodynia is an aggravating neuropathological condition in which light, physical touch leads to pain. Developing pharmaceutical agents to treat this condition requires extensive animal trials using a mouse model, and a laborious process of manually stroking inflicted mouse paws, with a brush or cotton swab, while recording responses to that stimulus. In this paper, we developed an autonomous testing mechanism to create repeatable stroking sensations for mice during dynamic allodynia testing. The chamber consists of a belt driven brush mechanism and light and dark chambers. Additionally, we conducted a human subjects study to determine the baseline variability in human-performed dynamic allodynia testing. Our tactile stoke display is capable of stroking a mouse paw between 1-5 mm/s with a repeatable force. In our human subject experiments, the user applied force ranged from 0.1-9.0 gF with a maximum standard deviation of 4.13 gF. In contrast, our device is capable of producing repeatable brush strokes at 0.69 gF (SD = 0.13 gF) and 1.78 gF (SD = 0.16 gF) for two brushes. Preliminary animal studies show that normal mice are not disturbed by the stroking sensation; however, mice afflicted with allodynia move away from it. On average the injured mice spent 90% of their time in a bright, adverse environment to avoid the brush, whereas normal mice only spent 40% of their time in the bright environment.Item A Critical Role for Dopamine D5 Receptors in Pain Chronicity in Male Mice(Soc Neuroscience) Megat, Salim; Shiers, Stephanie; Moy, Jamie K.; Barragán-Iglesias, Paulino; Pradhan, Grishma; Megat, Salim; Dussor, Gregory; Price, Theodore J.; 0000-0003-2186-6770 (Megat, S); 0000-0002-9646-1850 (Shiers, S); 0000-0001-8579-5540 (Moy, JK); 0000-0003-3178-8606 (Barragán-Iglesias, P); 0000-0002-6971-6221 (Price, TJ); Megat, Salim; Shiers, Stephanie; Moy, Jamie K.; Barragan-Iglesias, Paulino; Pradhan, Grishma; Seal, Rebecca P.; Dussor, Gregory; Price, Theodore J.Dopaminergic modulation of spinal cord plasticity has long been recognized, but circuits affected by this system and the precise receptor subtypes involved in this modulation have not been defined. Dopaminergic modulation from the A11 nucleus of the hypothalamus contributes to plasticity in a model of chronic pain called hyperalgesic priming. Here we tested the hypothesis that the key receptor subtype mediating this effect is the D5 receptor (D5R). We find that a spinally directed lesion of dopaminergic neurons reverses hyperalgesic priming in both sexes and that a D1/D5 antagonist transiently inhibits neuropathic pain. We used mice lacking D5Rs (DRD5KO mice) to show that carrageenan, interleukin 6, as well as BDNF-induced hyperalgesia and priming are reduced specifically in male mice. These male DRD5KO mice also show reduced formalin pain responses and decreased heat pain. To characterize the subtypes of dorsal horn neurons engaged by dopamine signaling in the hyperalgesic priming model, we used c-fos labeling. We find that a mixed D1/D5 agonist given spinally to primed mice activates a subset of neurons in lamina III and IV of the dorsal horn that coexpress PAX2, a transcription factor for GABAergic interneurons. In line with this, we show that gabazine, a GABA-A receptor antagonist, is antihyperalgesic in primed mice exposed to spinal administration of a D1/D5 agonist. Therefore, the D5R, in males, and the D1R, in females, exert a powerful influence over spinal cord circuitry in pathological pain likely via modulation of deep dorsal horn GABAergic neurons.Item eIF4E Phosphorylation Influences BDNF mRNA Translation in Mouse Dorsal Root Ganglion Neurons(Frontiers Media SA) Moy, Jamie K.; Khoutorsky, Arkady; Asiedu, Marina N.; Dussor, Gregory; Price, Theodore J.; 0000-0002-6971-6221 (Price, TJ); Moy, Jamie K.; Asiedu, Marina N.; Dussor, Gregory; Price, Theodore J.Plasticity in dorsal root ganglion (DRG) neurons that promotes pain requires activity-dependent mRNA translation. Protein synthesis inhibitors block the ability of many pain-promoting molecules to enhance excitability in DRG neurons and attenuate behavioral signs of pain plasticity. In line with this, we have recently shown that phosphorylation of the 5' cap-binding protein, eIF4E, plays a pivotal role in plasticity of DRG nociceptors in models of hyperalgesic priming. However, mRNA targets of eIF4E phosphorylation have not been elucidated in the DRG. Brain-derived neurotrophic factor (BDNF) signaling from nociceptors in the DRG to spinal dorsal horn neurons is an important mediator of hyperalgesic priming. Regulatory mechanisms that promote pain plasticity via controlling BDNF expression that is involved in promoting pain plasticity have not been identified. We show that phosphorylation of eIF4E is paramount for BDNF mRNA translation in the DRG. BDNF mRNA translation is reduced in mice lacking eIF4E phosphorylation (eIF4E^(S209A)) and pro-nociceptive factors fail to increase BDNF protein levels in the DRGs of these mice despite robust upregulation of BDNF-201 mRNA levels. Importantly, bypassing the DRG by giving intrathecal injection of BDNF in eIF4E^(S209A) mice creates a strong hyperalgesic priming response that is normally absent or reduced in these mice. We conclude that eIF4E phosphorylation-mediated translational control of BDNF expression is a key mechanism for nociceptor plasticity leading to hyperalgesic priming.Item The MNK–eIF4E Signaling Axis Contributes to Injury-Induced Nociceptive Plasticity and the Development of Chronic Pain(Society for Neuroscience) Moy, Jamie K.; Khoutorsky, A.; Black, Brian J.; Kuhn, Jasper L.; Barragán-Iglesias, Paulino; Megat, Salim; Burton, Michael D.; Burgos-Vega, Carolina C.; Melemedjian, O. K.; Boitano, S.; Vagner, J.; Gkogkas, C. G.; Pancrazio, Joseph J.; Mogil, J. S.; Dussor, Gregory; Sonenberg, N.; Price, Theodore J.; 0000 0001 3721 4764 (Dussor, G); 0000-0001-8579-5540 (Moy, JK); 0000-0001-8571-6486 (Black, B); 0000-0001-6524-9411 (Kuhn JL); 0000-0003-3178-8606 (Barragán-Iglesias, P); 0000-0002-6971-6221 (Price, TJ); Moy, Jamie K.; Asiedu, Marina N.; Black, Brian J.; Kuhn, Jasper L.; Barragán-Iglesias, Paulino; Megat, Salim; Burton, Michael D.; Burgos-Vega, Carolina C.; Pancrazio, Joseph J.; Dussor, Gregory; Price, Theodore J.Injury-induced sensitization of nociceptors contributes to pain states and the development of chronic pain. Inhibiting activity-dependent mRNA translation through mechanistic target of rapamycin and mitogen-activated protein kinase (MAPK) pathways blocks the development of nociceptor sensitization. These pathways convergently signal to the eukaryotic translation initiation factor (eIF) 4F complex to regulate the sensitization of nociceptors, but the details of this process are ill defined. Here we investigated the hypothesis that phosphorylation of the 5β cap-binding protein eIF4E by its specific kinase MAPK interacting kinases (MNKs) 1/2 is a key factor in nociceptor sensitization and the development of chronic pain. Phosphorylation of ser209 on eIF4E regulates the translation of a subset of mRNAs. We show that pronociceptive and inflammatory factors, such as nerve growth factor (NGF), interleukin-6 (IL-6), and carrageenan, produce decreased mechanical and thermal hypersensitivity, decreased affective pain behaviors, and strongly reduced hyperalgesic priming in mice lacking eIF4E phosphorylation (eIF4ES209A). Tests were done in both sexes, and no sex differences were found. Moreover, in patch-clamp electrophysiology and Ca2+ imaging experiments on dorsal root ganglion neurons, NGF- and IL-6-induced increases in excitability were attenuated in neurons from eIF4ES209A mice. These effects were recapitulated in Mnk1/2-/- mice and with the MNK1/2 inhibitor cercosporamide. We also find that cold hypersensitivity induced by peripheral nerve injury is reduced in eIF4ES209A and Mnk1/2-/- mice and following cercosporamide treatment. Our findings demonstrate that the MNK1/2–eIF4E signaling axis is an important contributing factor to mechanisms of nociceptor plasticity and the development of chronic pain.Item Extracellular Phosphorylation of a Receptor Tyrosine Kinase Controls Synaptic Localization of NMDA Receptors and Regulates Pathological PainHanamura, Kenji; Washburn, Halley R.; Sheffler-Collins, Sean I.; Xia, Nan L.; Henderson, Nathan; Tillu, Dipti V.; Hassler, Shayne; Spellman, Daniel S.; Zhang, Guoan; Neubert, Thomas A.; Price, Theodore J.; Dalva, Matthew B.; Hassler, Shayne; Price, Theodore J.Extracellular phosphorylation of proteins was suggested in the late 1800s when it was demonstrated that casein contains phosphate. More recently, extracellular kinases that phosphorylate extracellular serine, threonine, and tyrosine residues of numerous proteins have been identified. However, the functional significance of extracellular phosphorylation of specific residues in the nervous system is poorly understood. Here we show that synaptic accumulation of GluN2B-containing N-methyl-D-aspartate receptors (NMDARs) and pathological pain are controlled by ephrin-B-induced extracellular phosphorylation of a single tyrosine (p*Y504) in a highly conserved region of the fibronectin type III (FN3) domain of the receptor tyrosine kinase EphB2. Ligand-dependent Y504 phosphorylation modulates the EphB-NMDAR interaction in cortical and spinal cord neurons. Furthermore, Y504 phosphorylation enhances NMDAR localization and injury-induced pain behavior. By mediating inducible extracellular interactions that are capable of modulating animal behavior, extracellular tyrosine phosphorylation of EphBs may represent a previously unknown class of mechanism mediating protein interaction and function.Item Oestrogen Receptors Interact with the α-Catalytic Subunit of AMP-Activated Protein Kinase(Portland Press on behalf of the Biochemical Society) Lipovka, Yulia; Chen, Hao; Vagner, Josef; Price, Theodore J. (UT Dallas); Tsao, Tsu-Shuen; Konhilas, John P.Normal and pathological stressors engage the AMP-activated protein kinase (AMPK) signaling axis to protect the cell from energetic pressures. Sex steroid hormones also play a critical role in energy metabolism and significantly modify pathological progression of cardiac disease, diabetes/obesity, and cancer. AMPK is targeted by17β-estradiol (E2), the main circulating estrogen, but the mechanism by which E2 activates AMPK is currently unknown. Using an estrogen receptor α/β (ERα/β) positive (T47D) breast cancer cell line, we validated E2-dependent activation of AMPK that was mediated through ERα (not ERβ) by using three experimental strategies. A series of co-immunoprecipitation experiments showed that both ERs associated with AMPK in cancer and striated (skeletal and cardiac) muscle cells. We further demonstrated direct binding of ERs to the α-catalytic subunit of AMPK within the βγ-subunit binding domain. Finally, both ERs interacted with the upstream LKB1 kinase complex, which is required for E2-dependent activation of AMPK. We conclude that estradiol activates AMPK through ERα by direct interaction with the βγ-binding domain of AMPKα.; Copyright 2015 The Author(s).Item Pharmacogenetic Inhibition of eIF4E-Dependent Mmp9 mRNA Translation Reverses Fragile X Syndrome-Like Phenotypes(Cell Press) Gkogkas, Christos G.; Khoutorsky, Arkady; Cao, Ruifeng; Jafarnejad, Seyed Mehdi; Prager-Khoutorsky, Masha; Giannakas, Nikolaos; Kaminari, Archontia; Fragkouli, Apostolia; Nader, Karim; Price, Theodore J.; Konicek, Bruce W.; Graff, Jeremy R.; Tzinia, Athina K.; Lacaille, Jean-Claude; Sonenberg, NahumFragile X syndrome (FXS) is the leading genetic cause of autism. Mutations in Fmr1 (fragile X mental retardation 1 gene) engender exaggerated translation resulting in dendritic spine dysmorphogenesis, synaptic plasticity alterations, and behavioral deficits in mice, which are reminiscent of FXS phenotypes. Using postmortem brains from FXS patients and Fmr1 knockout mice (Fmr1(-/y)), we show that phosphorylation of the mRNA 5' cap binding protein, eukaryotic initiation factor 4E (eIF4E), is elevated concomitant with increased expression of matrix metalloproteinase 9 (MMP-9) protein. Genetic or pharmacological reduction of eIF4E phosphorylation rescued core behavioral deficits, synaptic plasticity alterations, and dendritic spine morphology defects via reducing exaggerated translation of Mmp9 mRNA in Fmr1(-/y) mice, whereas MMP-9 overexpression produced several FXS-like phenotypes. These results uncover a mechanism of regulation of synaptic function by translational control of Mmp-9 in FXS, which opens the possibility of new treatment avenues for the diverse neurological and psychiatric aspects of FXS.; CopyrightItem The Anti-Diabetic Drug Metformin Protects Against Chemotherapy-Induced Peripheral Neuropathy in a Mouse Model(Public Library of Science) Mao-Ying, Qi; Kavelaars, Annemieke; Krukowski, Karen; Huo, Xiao-Jiao; Zhou, Wenjun; Price, Theodore J.; Cleeland, Charles; Heijnen, Cobi J.Chemotherapy-induced peripheral neuropathy (CIPN) characterized by loss of sensory sensitivity and pain in hands and feet is the major dose-limiting toxicity of many chemotherapeutics. At present, there are no FDA-approved treatments for CIPN. The anti-diabetic drug metformin is the most widely used prescription drug in the world and improves glycemic control in diabetes patients. There is some evidence that metformin enhances the efficacy of cancer treatment. The aim of this study was to test the hypothesis that metformin protects against chemotherapy-induced neuropathic pain and sensory deficits. Mice were treated with cisplatin together with metformin or saline. Cisplatin induced increased sensitivity to mechanical stimulation (mechanical allodynia) as measured using the von Frey test. Co-administration of metformin almost completely prevented the cisplatin-induced mechanical allodynia. Co-administration of metformin also prevented paclitaxel-induced mechanical allodynia. The capacity of the mice to detect an adhesive patch on their hind paw was used as a novel indicator of chemotherapy-induced sensory deficits. Co-administration of metformin prevented the cisplatin-induced increase in latency to detect the adhesive patch indicating that metformin prevents sensory deficits as well. Moreover, metformin prevented the reduction in density of intra-epidermal nerve fibers (IENFs) in the paw that develops as a result of cisplatin treatment. We conclude that metformin protects against pain and loss of tactile function in a mouse model of CIPN. The finding that metformin reduces loss of peripheral nerve endings indicates that mechanism underlying the beneficial effects of metformin includes a neuroprotective activity. Because metformin is widely used for treatment of type II diabetes, has a broad safety profile, and is currently being tested as an adjuvant drug in cancer treatment, clinical translation of these findings could be rapidly achieved. ;