32 results on '"Salim Megat"'
Search Results
2. Integrative genetic analysis illuminates ALS heritability and identifies risk genes
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Salim Megat, Natalia Mora, Jason Sanogo, Olga Roman, Alberto Catanese, Najwa Ouali Alami, Axel Freischmidt, Xhuljana Mingaj, Hortense De Calbiac, François Muratet, Sylvie Dirrig-Grosch, Stéphane Dieterle, Nick Van Bakel, Kathrin Müller, Kirsten Sieverding, Jochen Weishaupt, Peter Munch Andersen, Markus Weber, Christoph Neuwirth, Markus Margelisch, Andreas Sommacal, Kristel R. Van Eijk, Jan H. Veldink, Project Mine Als Sequencing Consortium, Géraldine Lautrette, Philippe Couratier, Agnès Camuzat, Isabelle Le Ber, Maurizio Grassano, Adriano Chio, Tobias Boeckers, Albert C. Ludolph, Francesco Roselli, Deniz Yilmazer-Hanke, Stéphanie Millecamps, Edor Kabashi, Erik Storkebaum, Chantal Sellier, and Luc Dupuis
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Science - Abstract
Abstract Amyotrophic lateral sclerosis (ALS) has substantial heritability, in part shared with fronto-temporal dementia (FTD). We show that ALS heritability is enriched in splicing variants and in binding sites of 6 RNA-binding proteins including TDP-43 and FUS. A transcriptome wide association study (TWAS) identified 6 loci associated with ALS, including in NUP50 encoding for the nucleopore basket protein NUP50. Independently, rare variants in NUP50 were associated with ALS risk (P = 3.71.10−03; odds ratio = 3.29; 95%CI, 1.37 to 7.87) in a cohort of 9,390 ALS/FTD patients and 4,594 controls. Cells from one patient carrying a NUP50 frameshift mutation displayed a decreased level of NUP50. Loss of NUP50 leads to death of cultured neurons, and motor defects in Drosophila and zebrafish. Thus, our study identifies alterations in splicing in neurons as critical in ALS and provides genetic evidence linking nuclear pore defects to ALS.
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- 2023
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3. Wild-type FUS corrects ALS-like disease induced by cytoplasmic mutant FUS through autoregulation
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Inmaculada Sanjuan-Ruiz, Noé Govea-Perez, Melissa McAlonis-Downes, Stéphane Dieterle, Salim Megat, Sylvie Dirrig-Grosch, Gina Picchiarelli, Diana Piol, Qiang Zhu, Brian Myers, Chao-Zong Lee, Don W Cleveland, Clotilde Lagier-Tourenne, Sandrine Da Cruz, and Luc Dupuis
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Amyotrophic lateral sclerosis ,Fronto-temporal dementia ,Mouse models ,RNA-binding proteins ,FUS ,Autoregulation ,Neurology. Diseases of the nervous system ,RC346-429 ,Geriatrics ,RC952-954.6 - Abstract
Abstract Mutations in FUS, an RNA-binding protein involved in multiple steps of RNA metabolism, are associated with the most severe forms of amyotrophic lateral sclerosis (ALS). Accumulation of cytoplasmic FUS is likely to be a major culprit in the toxicity of FUS mutations. Thus, preventing cytoplasmic mislocalization of the FUS protein may represent a valuable therapeutic strategy. FUS binds to its own pre-mRNA creating an autoregulatory loop efficiently buffering FUS excess through multiple proposed mechanisms including retention of introns 6 and/or 7. Here, we introduced a wild-type FUS gene allele, retaining all intronic sequences, in mice whose heterozygous or homozygous expression of a cytoplasmically retained FUS protein (Fus ∆NLS) was previously shown to provoke ALS-like disease or postnatal lethality, respectively. Wild-type FUS completely rescued the early lethality caused by the two Fus ∆NLS alleles, and improved the age-dependent motor deficits and reduced lifespan caused by heterozygous expression of mutant FUS∆NLS. Mechanistically, wild-type FUS decreased the load of cytoplasmic FUS, increased retention of introns 6 and 7 in the endogenous mouse Fus mRNA, and decreased expression of the mutant mRNA. Thus, the wild-type FUS allele activates the homeostatic autoregulatory loop, maintaining constant FUS levels and decreasing the mutant protein in the cytoplasm. These results provide proof of concept that an autoregulatory competent wild-type FUS expression could protect against this devastating, currently intractable, neurodegenerative disease.
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- 2021
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4. Cytoplasmic FUS triggers early behavioral alterations linked to cortical neuronal hyperactivity and inhibitory synaptic defects
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Jelena Scekic-Zahirovic, Inmaculada Sanjuan-Ruiz, Vanessa Kan, Salim Megat, Pierre De Rossi, Stéphane Dieterlé, Raphaelle Cassel, Marguerite Jamet, Pascal Kessler, Diana Wiesner, Laura Tzeplaeff, Valérie Demais, Sonu Sahadevan, Katharina M. Hembach, Hans-Peter Muller, Gina Picchiarelli, Nibha Mishra, Stefano Antonucci, Sylvie Dirrig-Grosch, Jan Kassubek, Volker Rasche, Albert Ludolph, Anne-Laurence Boutillier, Francesco Roselli, Magdalini Polymenidou, Clotilde Lagier-Tourenne, Sabine Liebscher, and Luc Dupuis
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Science - Abstract
Mutations in the RNA binding protein FUS are associated with ALS. Here the authors show that in FUS knock-in mice there is a progressive increase in neuronal activity in the frontal cortex which is associated with altered synaptic gene expression.
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- 2021
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5. Synaptic FUS accumulation triggers early misregulation of synaptic RNAs in a mouse model of ALS
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Sonu Sahadevan, Katharina M. Hembach, Elena Tantardini, Manuela Pérez-Berlanga, Marian Hruska-Plochan, Salim Megat, Julien Weber, Petra Schwarz, Luc Dupuis, Mark D. Robinson, Pierre De Rossi, and Magdalini Polymenidou
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Science - Abstract
Mutations in the RNA-binding protein FUS contribute to ALS. Here the authors use CLIP-seq on synaptoneurosomes to identify proteins associated with synapse organization and plasticity that are differentially regulated in a knock-in ALS mouse model.
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- 2021
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6. Sex differences in the role of atypical PKC within the basolateral nucleus of the amygdala in a mouse hyperalgesic priming model
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Daniela Baptista-de-Souza, Diana Tavares-Ferreira, Salim Megat, Ishwarya Sankaranarayanan, Stephanie Shiers, Christopher M. Flores, Sourav Ghosh, Ricardo Luiz Nunes-de-Souza, Azair Canto-de-Souza, and Theodore J. Price
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Sex differences ,Hyperalgesic priming ,Basolateral amygdala ,ZIP ,aPKC ,GluA2 ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Though sex differences in chronic pain have been consistently described in the literature, their underlying neural mechanisms are poorly understood. Previous work in humans has demonstrated that men and women differentially invoke distinct brain regions and circuits in coping with subjective pain unpleasantness. The goal of the present work was to elucidate the molecular mechanisms in the basolateral nucleus of the amygdala (BLA) that modulate hyperalgesic priming, a pain plasticity model, in males and females. We used plantar incision as the first, priming stimulus and prostaglandin E2 (PGE2) as the second stimulus. We sought to assess whether hyperalgesic priming can be prevented or reversed by pharmacologically manipulating molecular targets in the BLA of male or female mice. We found that administering ZIP, a cell-permeable inhibitor of aPKC, into the BLA attenuated aspects of hyperalgesic priming induced by plantar incision in males and females. However, incision only upregulated PKCζ/PKMζ immunoreactivity in the BLA of male mice, and deficits in hyperalgesic priming were seen only when we restricted our analysis to male Prkcz−/− mice. On the other hand, intra-BLA microinjections of pep2m, a peptide that interferes with the trafficking and function of GluA2-containing AMPA receptors, a downstream target of aPKC, reduced mechanical hypersensitivity after plantar incision and disrupted the development of hyperalgesic priming in both male and female mice. In addition, pep2m treatment reduced facial grimacing and restored aberrant behavioral responses in the sucrose splash test in male and female primed mice. Immunofluorescence results demonstrated upregulation of GluA2 expression in the BLA of male and female primed mice, consistent with pep2m findings. We conclude that, in a model of incision-induced hyperalgesic priming, PKCζ/PKMζ in the BLA is critical for the development of hyperalgesic priming in males, while GluA2 in the BLA is crucial for the expression of both reflexive and affective pain-related behaviors in both male and female mice in this model. Our findings add to a growing body of evidence of sex differences in molecular pain mechanisms in the brain.
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- 2020
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7. Therapeutic opportunities for pain medicines via targeting of specific translation signaling mechanisms
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Salim Megat and Theodore J. Price
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Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
As the population of the world ages and as more and more people survive diseases that used to be primary causes of mortality, the incidence of severe chronic pain in most of the world has risen dramatically. This type of pain is very difficult to treat and the opioid overdose epidemic that has become a leading cause of death in the United States and other parts of the world highlights the urgent need to develop new pain therapeutics. A common underlying cause of severe chronic pain is a phenotypic change in pain-sensing neurons in the peripheral nervous system called nociceptors. These neurons play a vital role in detecting potentially injurious stimuli, but when these neurons start to detect very low levels of inflammatory meditators or become spontaneously active, they send spurious pain signals to the brain that are significant drivers of chronic pain. An important question is what drives this phenotypic shift in nociceptors from quiescence under most conditions to sensitization to a broad variety of stimuli and spontaneous activity. The goal of this review is to discuss the critical role that specific translation regulation signaling pathways play in controlling gene expression changes that drive nociceptor sensitization and may underlie the development of spontaneous activity. The focus will be on advances in technologies that allow for identification of such targets and on developments in pharmacology around translation regulation signaling that may yield new pain therapeutics. A key advantage of pharmacological manipulation of these signaling events is that they may reverse phenotypic shifts in nociceptors that drive chronic pain thereby creating the first generation of disease modifying drugs for chronic pain. Keywords: mTOR, MNK, eIF4E, eIF4A, AMPK, Nociceptor, Sensitization
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- 2018
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8. Inhibition of Poly(A)-binding protein with a synthetic RNA mimic reduces pain sensitization in mice
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Paulino Barragán-Iglesias, Tzu-Fang Lou, Vandita D. Bhat, Salim Megat, Michael D. Burton, Theodore J. Price, and Zachary T. Campbell
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Science - Abstract
Poly(A)-binding protein (PABP) is an RNA binding protein with translation function. Here, Barragán-Iglesias and colleagues devise an RNA mimic that inhibits PABP activity, and show that inhibitors can reduce animal’s pain response in vivo when injected locally.
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- 2018
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9. Temporal and sex differences in the role of BDNF/TrkB signaling in hyperalgesic priming in mice and rats
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Jamie K. Moy, Thomas Szabo-Pardi, Dipti V. Tillu, Salim Megat, Grishma Pradhan, Moeno Kume, Marina N. Asiedu, Michael D. Burton, Gregory Dussor, and Theodore J. Price
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Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Brain-derived neurotrophic factor (BDNF) signaling through its cognate receptor, TrkB, is a well-known promoter of synaptic plasticity at nociceptive synapses in the dorsal horn of the spinal cord. Existing evidence suggests that BDNF/TrkB signaling in neuropathic pain is sex dependent. We tested the hypothesis that the effects of BDNF/TrkB signaling in hyperalgesic priming might also be sexually dimorphic. Using the incision postsurgical pain model in male mice, we show that BDNF sequestration with TrkB-Fc administered at the time of surgery blocks the initiation and maintenance of hyperalgesic priming. However, when BDNF signaling was blocked prior to the precipitation of hyperalgesic priming with prostaglandin E2 (PGE2), priming was not reversed. This result is in contrast to our findings in male mice with interleukin-6 (IL6) as the priming stimulus where TrkB-Fc was effective in reversing the maintenance of hyperalgesic priming. Furthermore, in IL6-induced hyperalgesic priming, the BDNF sequestering agent, TrkB-fc, was effective in reversing the maintenance of hyperalgesic priming in male mice; however, when this experiment was conducted in female mice, we did not observe any effect of TrkB-fc. This markedly sexual dimorphic effect in mice is consistent with recent studies showing a similar effect in neuropathic pain models. We tested whether the sexual dimorphic role for BDNF was consistent across species. Importantly, we find that this sexual dimorphism does not occur in rats where TrkB-fc reverses hyperalgesic priming fully in both sexes. Finally, to determine the source of BDNF in hyperalgesic priming in mice, we used transgenic mice (Cx3cr1CreER × Bdnfflx/flx mice) with BDNF eliminated from microglia. From these experiments we conclude that BDNF from microglia does not contribute to hyperalgesic priming and that the key source of BDNF for hyperalgesic priming is likely nociceptors in the dorsal root ganglion. These experiments demonstrate the importance of testing mechanistic hypotheses in both sexes in multiple species to gain insight into complex biology underlying chronic pain. Keywords: BDNF, Hyperalgesic priming, TrkB, Sex differences, IL6
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- 2019
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10. Antidepressants suppress neuropathic pain by a peripheral β2-adrenoceptor mediated anti-TNFα mechanism
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Yohann Bohren, Luc-Henri Tessier, Salim Megat, Hugues Petitjean, Sylvain Hugel, Dorothée Daniel, Mélanie Kremer, Sylvie Fournel, Lutz Hein, Rémy Schlichter, Marie-José Freund-Mercier, Ipek Yalcin, and Michel Barrot
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Allodynia ,Antidepressant ,Adrenoceptor ,Cytokine ,Dorsal root ganglia ,Satellite ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Neuropathic pain is pain arising as a direct consequence of a lesion or disease affecting the somatosensory system. It is usually chronic and challenging to treat. Some antidepressants are first-line pharmacological treatments for neuropathic pain. The noradrenaline that is recruited by the action of the antidepressants on reuptake transporters has been proposed to act through β2-adrenoceptors (β2-ARs) to lead to the observed therapeutic effect. However, the complex downstream mechanism mediating this action remained to be identified. In this study, we demonstrate in a mouse model of neuropathic pain that an antidepressant's effect on neuropathic allodynia involves the peripheral nervous system and the inhibition of cytokine tumor necrosis factor α (TNFα) production. The antiallodynic action of nortriptyline is indeed lost after peripheral sympathectomy, but not after lesion of central descending noradrenergic pathways. More particularly, we report that antidepressant-recruited noradrenaline acts, within dorsal root ganglia, on β2-ARs expressed by non-neuronal satellite cells. This stimulation of β2-ARs decreases the neuropathy-induced production of membrane-bound TNFα, resulting in relief of neuropathic allodynia. This indirect anti-TNFα action was observed with the tricyclic antidepressant nortriptyline, the selective serotonin and noradrenaline reuptake inhibitor venlafaxine and the β2-AR agonist terbutaline. Our data revealed an original therapeutic mechanism that may open novel research avenues for the management of painful peripheral neuropathies.
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- 2013
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11. Haptic stroke testbed for pharmacological evaluation of dynamic allodynia in mouse models.
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Jin Lee, Brian J. Atwood, Salim Megat, Gregory Dussor, Theodore J. Price, and Ann Majewicz Fey
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- 2018
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12. Sex Differences in Nociceptor Translatomes Contribute to Divergent Prostaglandin Signaling in Male and Female Mice
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Armen N. Akopian, Paulino Barragán-Iglesias, Andi Wangzhou, Galo L. Mejia, Stephanie Shiers, Diana Tavares-Ferreira, Salim Megat, Ishwarya Sankaranarayanan, Gregory Dussor, Ruta Uttarkar, Pradipta R. Ray, and Theodore J. Price
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Male ,0301 basic medicine ,Untranslated region ,Nervous system ,medicine.medical_specialty ,Prostaglandin ,Biology ,Article ,Transcriptome ,Mice ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Dorsal root ganglion ,Ganglia, Spinal ,Internal medicine ,medicine ,Animals ,Gene ,Biological Psychiatry ,Sex Characteristics ,Messenger RNA ,Chronic pain ,Nociceptors ,medicine.disease ,Nociception ,030104 developmental biology ,Endocrinology ,medicine.anatomical_structure ,chemistry ,Prostaglandins ,Nociceptor ,Female ,Prostaglandin D2 ,030217 neurology & neurosurgery ,Signal Transduction - Abstract
BackgroundThere are clinically relevant sex differences in acute and chronic pain mechanisms, but we are only beginning to understand their mechanistic basis. Transcriptome analyses of rodent whole dorsal root ganglion (DRG) have revealed sex differences, mostly in immune cells. We examined the transcriptome and translatome of the mouse DRG with the goal of identifying sex differences.MethodsWe used Translating Ribosome Affinity Purification (TRAP) sequencing and behavioral pharmacology to test the hypothesis that nociceptor (Nav1.8 expressing neurons) translatomes would differ by sex.ResultsWe found 66 genes whose mRNA were sex-differentially bound to nociceptor ribosomes. Many of these genes have known neuronal functions but have not been explored in sex differences in pain. We focused on Ptgds, which was increased in female mice. The mRNA encodes the prostaglandin D2 (PGD2) synthesizing enzyme. We observed increased Ptgds protein and PGD2 in female mouse DRG. The Ptgds inhibitor AT-56 caused intense pain behaviors in male mice but was only effective at high doses in females. Conversely, female mice responded more robustly to another major prostaglandin, PGE2, than did male mice. Ptgds protein expression was also higher in female cortical neurons, suggesting DRG findings may be generalizable to other nervous system structures.ConclusionsNociceptor TRAP sequencing (TRAP-seq) reveals unexpected sex differences in one of the oldest known nociceptive signaling molecule families, the prostaglandins. Our results demonstrate that translatome analysis reveals physiologically relevant sex differences important for fundamental protective behaviors driven by nociceptors.
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- 2022
13. Intercellular Arc Signaling Regulates Vasodilation
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Pradipta R. Ray, Tarjani Shukla, June Bryan de la Peña, Jason D. Shepherd, Sarah Loerch, Lokesh Basavarajappa, Paulino Barragán-Iglesias, Salim Megat, Jane Song, Zachary T. Campbell, Nikesh Kunder, Andi Wanghzou, Kenneth Hoyt, Dominique James, Jamie K. Moy, Theodore J. Price, Oswald Steward, and Tzu-Fang Lou
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Male ,Nociception ,Cell signaling ,Nerve Tissue Proteins ,Inflammation ,Biology ,Mice ,Dorsal root ganglion ,Ganglia, Spinal ,medicine ,Animals ,Research Articles ,Mice, Knockout ,Neurons ,Neurogenic inflammation ,Arc (protein) ,General Neuroscience ,Nociceptors ,Peripheral Nervous System Diseases ,Cell biology ,Vasodilation ,Cytoskeletal Proteins ,medicine.anatomical_structure ,Nociceptor ,medicine.symptom ,Immediate early gene ,Signal Transduction - Abstract
Injury responses require communication between different cell types in the skin. Sensory neurons contribute to inflammation and can secrete signaling molecules that affect non-neuronal cells. Despite the pervasive role of translational regulation in nociception, the contribution of activity-dependent protein synthesis to inflammation is not well understood. To address this problem, we examined the landscape of nascent translation in murine dorsal root ganglion (DRG) neurons treated with inflammatory mediators using ribosome profiling. We identified the activity-dependent gene, Arc, as a target of translation in vitro and in vivo. Inflammatory cues promote local translation of Arc in the skin. Arc-deficient male mice display exaggerated paw temperatures and vasodilation in response to an inflammatory challenge. Since Arc has recently been shown to be released from neurons in extracellular vesicles (EVs), we hypothesized that intercellular Arc signaling regulates the inflammatory response in skin. We found that the excessive thermal responses and vasodilation observed in Arc defective mice are rescued by injection of Arc-containing EVs into the skin. Our findings suggest that activity-dependent production of Arc in afferent fibers regulates neurogenic inflammation potentially through intercellular signaling. SIGNIFICANCE STATEMENT Nociceptors play prominent roles in pain and inflammation. We examined rapid changes in the landscape of nascent translation in cultured dorsal root ganglia (DRGs) treated with a combination of inflammatory mediators using ribosome profiling. We identified several hundred transcripts subject to rapid preferential translation. Among them is the immediate early gene (IEG) Arc. We provide evidence that Arc is translated in afferent fibers in the skin. Arc-deficient mice display several signs of exaggerated inflammation which is normalized on injection of Arc containing extracellular vesicles (EVs). Our work suggests that noxious cues can trigger Arc production by nociceptors which in turn constrains neurogenic inflammation in the skin.
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- 2021
14. Loss of nucleoporin Nup50 is a risk factor for amyotrophic lateral sclerosis
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Jan H. Veldink, Edor Kabashi, Sylvie Dirrig-Grosch, Peter M Andersen, Najwa Ouali Alami, Luc Dupuis, Kirsten Sieverding, Axel Freischmidt, Natalia Mora, Albert C. Ludolph, Tobias M. Boeckers, Markus Margelisch, Philippe Couratier, Francesco Roselli, François Muratet, Andreas Sommacal, Chantal Sellier, Géraldine Lautrette, Erik Storkebaum, Markus Weber, Nick H.M. van Bakel, Stéphane Dieterlé, Stéphanie Millecamps, Kristel R. van Eijk, Jochen H. Weishaupt, Alberto Catanese, Kathrin Muller, Salim Megat, Xhuljana Mingaj, Christoph Neuwirth, Jason Sanogo, Hortense de Calbiac, and Deniz Yilmazer-Hanke
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Genetics ,BCS1L ,RNA splicing ,Gene expression ,medicine ,RNA-binding protein ,Genome-wide association study ,Nucleoporin ,Amyotrophic lateral sclerosis ,Biology ,medicine.disease ,Gene - Abstract
The genetic basis of amyotrophic lateral sclerosis (ALS) is still incompletely understood. Using two independent genetic strategies, we show here that a large part of ALS heritability lies in genes expressed in inhibitory and excitatory neurons, especially at splicing sites regulated by a defined set of RNA binding proteins including TDP-43 and FUS. We conducted a transcriptome wide association study (TWAS) and identified 59 loci associated with ALS, including 14 previously identified genes, some of them not previously reaching significance in genome wide association studies. Among the 45 novel genes, several genes are involved in pathways known to be affected in ALS such as mitochondrial metabolism (including ATP5H, ATP5D, BCS1L), proteostasis (including COPS7A, G2E3, TMEM175, USP35) or gene expression and RNA metabolism (including ARID1B, ATXN3, PTBP2, TAF10). Interestingly, decreased expression of NUP50, a constrained gene encoding a nuclear pore basket protein, was associated with ALS in TWAS (Zscore = −4, FDR = 0.034). 11 potentially pathogenic variants (CADD score > 20) in 23 patients were identified in the NUP50 gene, most of them in the region of the protein mediating interaction with Importin alpha, and including 2 frameshift mutations. In cells from two patients carrying NUP50 variants, we showed decreased levels of NUP50 protein. Importantly, knocking down Nup50 led to increased neuronal death associated with p62 and nucleoporin inclusions in cultured neurons, and motor defects in Drosophila and zebrafish models. In all, our study identifies alterations in splicing in neurons as a critical pathogenic process in ALS, uncovers several new loci potentially contributing to ALS missing heritability, and provides genetic evidence linking nuclear pore defects to ALS.
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- 2021
15. Synaptic FUS accumulation triggers early misregulation of synaptic RNAs in a mouse model of ALS
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Pierre De Rossi, Marian Hruska-Plochan, Magdalini Polymenidou, Mark D. Robinson, Elena Tantardini, Luc Dupuis, Salim Megat, Julien Weber, Katharina M. Hembach, Petra Schwarz, Sonu Sahadevan, Manuela Pérez-Berlanga, Universität Zürich [Zürich] = University of Zurich (UZH), Mécanismes Centraux et Périphériques de la Neurodégénérescence, Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM), University hospital of Zurich [Zurich], Dieterle, Stéphane, University of Zurich, and Polymenidou, Magdalini
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0301 basic medicine ,[SDV]Life Sciences [q-bio] ,General Physics and Astronomy ,MESH: Synapses ,Synapse ,Mice ,0302 clinical medicine ,MESH: Animals ,Amyotrophic lateral sclerosis ,MESH: Amyotrophic Lateral Sclerosis ,Cerebral Cortex ,Multidisciplinary ,MESH: RNA-Binding Protein FUS ,Neurodegeneration ,10124 Institute of Molecular Life Sciences ,3100 General Physics and Astronomy ,Cell biology ,[SDV] Life Sciences [q-bio] ,GABAergic ,Microtubule-Associated Proteins ,MESH: Cell Nucleus ,Science ,1600 General Chemistry ,Genetics and Molecular Biology ,Biology ,General Biochemistry, Genetics and Molecular Biology ,Article ,03 medical and health sciences ,1300 General Biochemistry, Genetics and Molecular Biology ,MESH: Mice, Inbred C57BL ,MESH: RNA ,medicine ,Animals ,RNA, Messenger ,Synapse organization ,MESH: Mice ,MESH: RNA, Messenger ,RNA metabolism ,Cell Nucleus ,Messenger RNA ,Amyotrophic Lateral Sclerosis ,RNA ,General Chemistry ,medicine.disease ,MESH: Cerebral Cortex ,Mice, Inbred C57BL ,MESH: Microtubule-Associated Proteins ,Disease Models, Animal ,030104 developmental biology ,General Biochemistry ,Synapses ,570 Life sciences ,biology ,RNA-Binding Protein FUS ,MESH: Disease Models, Animal ,11493 Department of Quantitative Biomedicine ,030217 neurology & neurosurgery ,Nuclear localization sequence - Abstract
Mutations disrupting the nuclear localization of the RNA-binding protein FUS characterize a subset of amyotrophic lateral sclerosis patients (ALS-FUS). FUS regulates nuclear RNAs, but its role at the synapse is poorly understood. Using super-resolution imaging we determined that the localization of FUS within synapses occurs predominantly near the vesicle reserve pool of presynaptic sites. Using CLIP-seq on synaptoneurosomes, we identified synaptic FUS RNA targets, encoding proteins associated with synapse organization and plasticity. Significant increase of synaptic FUS during early disease in a mouse model of ALS was accompanied by alterations in density and size of GABAergic synapses. mRNAs abnormally accumulated at the synapses of 6-month-old ALS-FUS mice were enriched for FUS targets and correlated with those depicting increased short-term mRNA stability via binding primarily on multiple exonic sites. Our study indicates that synaptic FUS accumulation in early disease leads to synaptic impairment, potentially representing an initial trigger of neurodegeneration., Mutations in the RNA-binding protein FUS contribute to ALS. Here the authors use CLIP-seq on synaptoneurosomes to identify proteins associated with synapse organization and plasticity that are differentially regulated in a knock-in ALS mouse model.
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- 2021
16. Wild-type FUS corrects ALS-like disease induced by cytoplasmic mutant FUS through autoregulation
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Melissa McAlonis-Downes, Sandrine Da Cruz, Salim Megat, Qiang Zhu, Noé Govea-Perez, Diana Piol, Gina Picchiarelli, Stéphane Dieterlé, Brian Myers, Luc Dupuis, Don W. Cleveland, Clotilde Lagier-Tourenne, Sylvie Dirrig-Grosch, Inmaculada Sanjuan-Ruiz, and Chao-Zong Lee
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0303 health sciences ,Messenger RNA ,Mutant ,Wild type ,Intron ,Biology ,medicine.disease ,Cell biology ,03 medical and health sciences ,Exon ,0302 clinical medicine ,Mutant protein ,medicine ,Allele ,Amyotrophic lateral sclerosis ,030217 neurology & neurosurgery ,030304 developmental biology - Abstract
Mutations in FUS, an RNA-binding protein involved in multiple steps of RNA metabolism, are associated with the most severe forms of amyotrophic lateral sclerosis (ALS). Accumulation of cytoplasmic FUS is likely to be a major culprit in the toxicity of FUS mutations. Thus, preventing cytoplasmic mislocalization of the FUS protein may represent a valuable therapeutic strategy. FUS binds to its own pre-mRNA creating an autoregulatory loop efficiently buffering FUS excess through multiple proposed mechanisms including retention of introns 6 and/or 7. Here, we introduced a wild-type FUS gene allele, retaining all intronic sequences, in mice whose heterozygous or homozygous expression of a cytoplasmically retained FUS protein (FusΔNLS) was previously shown to provoke ALS-like disease or postnatal lethality, respectively. Wild-type FUS completely rescued the early lethality caused by the two FusΔNLS alleles, and improved age-dependent motor deficit and reduced lifespan associated with the heterozygous expression of FusΔNLS. Mechanistically, wild-type FUS decreased the load of cytoplasmic FUS, increased exon 7 skipping and retention of introns 6 and 7 in the endogenous mouse Fus mRNA, leading to decreased expression of the mutant mRNA. Thus, the wild-type FUS allele activates the homeostatic autoregulatory loop, maintaining constant FUS levels and decreasing the mutant protein in the cytoplasm. These results provide proof of concept that an autoregulatory competent wild-type FUS expression could protect against this devastating, currently intractable, neurodegenerative disease.
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- 2020
17. Antiallodynic action of phosphodiesterase inhibitors in a mouse model of peripheral nerve injury
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Salim Megat, Sylvain Hugel, Sarah H. Journée, Yohann Bohren, Adrien Lacaud, Vincent Lelièvre, Stéphane Doridot, Pascal Villa, Jean-Jacques Bourguignon, Eric Salvat, Remy Schlichter, Marie-José Freund-Mercier, Ipek Yalcin, and Michel Barrot
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Pharmacology ,Disease Models, Animal ,Mice ,Cellular and Molecular Neuroscience ,Hyperalgesia ,Peripheral Nerve Injuries ,Tumor Necrosis Factor-alpha ,Animals ,Neuralgia ,Phosphodiesterase 4 Inhibitors ,Phosphodiesterase 5 Inhibitors ,Rolipram - Abstract
Neuropathic pain arises as a consequence of a lesion or disease affecting the somatosensory nervous system. It is accompanied by neuronal and non-neuronal alterations, including alterations in intracellular second messenger pathways. Cellular levels of 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) are regulated by phosphodiesterase (PDE) enzymes. Here, we studied the impact of PDE inhibitors (PDEi) in a mouse model of peripheral nerve injury induced by placing a cuff around the main branch of the sciatic nerve. Mechanical hypersensitivity, evaluated using von Frey filaments, was relieved by sustained treatment with the non-selective PDEi theophylline and ibudilast (AV-411), with PDE4i rolipram, etazolate and YM-976, and with PDE5i sildenafil, zaprinast and MY-5445, but not by treatments with PDE1i vinpocetine, PDE2i EHNA or PDE3i milrinone. Using pharmacological and knock-out approaches, we show a preferential implication of delta opioid receptors in the action of the PDE4i rolipram and of both mu and delta opioid receptors in the action of the PDE5i sildenafil. Calcium imaging highlighted a preferential action of rolipram on dorsal root ganglia non-neuronal cells, through PDE4B and PDE4D inhibition. Rolipram had anti-neuroimmune action, as shown by its impact on levels of the pro-inflammatory cytokine tumor necrosis factor-α (TNFα) in the dorsal root ganglia of mice with peripheral nerve injury, as well as in human peripheral blood mononuclear cells (PBMCs) stimulated with lipopolysaccharides. This study suggests that PDEs, especially PDE4 and 5, may be targets of interest in the treatment of neuropathic pain.
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- 2022
18. Intercellular Arc signaling regulates vasodilation
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Salim Megat, N. Prakash, J. B. De La Pena, Paulino Barragán-Iglesias, Jamie K. Moy, Pradipta R. Ray, Jane Song, Theodore J. Price, Zachary T. Campbell, Andi Wanghzou, Kenneth Hoyt, Tzu-Fang Lou, Tarjani Shukla, Lokesh Basavarajappa, Sarah Loerch, Oswald Steward, and Jason D. Shepherd
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Male ,Nociception ,Cell type ,Cell signaling ,Arc capsid ,Spinal ,Knockout ,1.1 Normal biological development and functioning ,Nerve Tissue Proteins ,Inflammation ,Medical and Health Sciences ,Mice ,local translation ,Underpinning research ,Translational regulation ,Genetics ,medicine ,Animals ,2.1 Biological and endogenous factors ,Secretion ,Aetiology ,vasodilation ,Neurons ,ribosome profiling ,Neurogenic inflammation ,Neurology & Neurosurgery ,Arc (protein) ,Chemistry ,Pain Research ,Psychology and Cognitive Sciences ,Neurosciences ,Nociceptors ,Peripheral Nervous System Diseases ,translational control ,Translation (biology) ,Arc ,Cell biology ,Cytoskeletal Proteins ,DRG ,neuroinflamation ,Ganglia ,Chronic Pain ,Extracellular vesicle ,medicine.symptom ,Signal Transduction - Abstract
Injury responses require communication between different cell types in the skin. Sensory neurons contribute to inflammation and can secrete signaling molecules that affect non-neuronal cells. Despite the pervasive role of translational regulation in nociception, the contribution of activity-dependent protein synthesis to inflammation is not well understood. To address this problem, we examined the landscape of nascent translation in murine dorsal root ganglion (DRG) neurons treated with inflammatory mediators using ribosome profiling. We identified the activity-dependent gene, Arc, as a target of translation in vitro and in vivo Inflammatory cues promote local translation of Arc in the skin. Arc-deficient male mice display exaggerated paw temperatures and vasodilation in response to an inflammatory challenge. Since Arc has recently been shown to be released from neurons in extracellular vesicles (EVs), we hypothesized that intercellular Arc signaling regulates the inflammatory response in skin. We found that the excessive thermal responses and vasodilation observed in Arc defective mice are rescued by injection of Arc-containing EVs into the skin. Our findings suggest that activity-dependent production of Arc in afferent fibers regulates neurogenic inflammation potentially through intercellular signaling.SIGNIFICANCE STATEMENT Nociceptors play prominent roles in pain and inflammation. We examined rapid changes in the landscape of nascent translation in cultured dorsal root ganglia (DRGs) treated with a combination of inflammatory mediators using ribosome profiling. We identified several hundred transcripts subject to rapid preferential translation. Among them is the immediate early gene (IEG) Arc. We provide evidence that Arc is translated in afferent fibers in the skin. Arc-deficient mice display several signs of exaggerated inflammation which is normalized on injection of Arc containing extracellular vesicles (EVs). Our work suggests that noxious cues can trigger Arc production by nociceptors which in turn constrains neurogenic inflammation in the skin.
- Published
- 2020
19. Sex differences in the role of atypical PKC within the basolateral nucleus of the amygdala in a mouse hyperalgesic priming model
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Azair Canto-de-Souza, Stephanie Shiers, Sourav Ghosh, Christopher M. Flores, Ishwarya Sankaranarayanan, Diana Tavares-Ferreira, Ricardo Luiz Nunes-de-Souza, Salim Megat, Theodore J. Price, Daniela Baptista-de-Souza, Universidade Federal de São Carlos (UFSCar), School of Behavioral and Brain Sciences and Center for Advanced Pain Studies, Neuroscience Therapeutic Area, Yale University School of Medicine, and Universidade Estadual Paulista (Unesp)
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0301 basic medicine ,medicine.medical_specialty ,Neuroscience (miscellaneous) ,AMPA receptor ,Stimulus (physiology) ,Immunofluorescence ,Amygdala ,lcsh:RC321-571 ,aPKC ,03 medical and health sciences ,Hyperalgesic priming ,0302 clinical medicine ,Downregulation and upregulation ,Internal medicine ,Basolateral amygdala ,Sex differences ,medicine ,Original Research Article ,Prostaglandin E2 ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,medicine.diagnostic_test ,business.industry ,Chronic pain ,biochemical phenomena, metabolism, and nutrition ,medicine.disease ,GluA2 ,030104 developmental biology ,Anesthesiology and Pain Medicine ,medicine.anatomical_structure ,Endocrinology ,Neurology (clinical) ,business ,ZIP ,030217 neurology & neurosurgery ,medicine.drug - Abstract
Highlights • Intra-BLA ZIP, a cell-permeable inhibitor of aPKC, attenuated hyperalgesic priming induced by plantar incision in both sexes. • Priming upregulated aPKC in the BLA only in male mice. • Deficits in hyperalgesic priming were only seen in male Prkcz−/− mice. • Pep2m, a peptide that interferes GluA2 AMPA receptors, reduced priming in both male and female mice. • GluA2 expression was upregulated in the BLA of male and female primed mice. • GluA2 in the BLA is crucial for the initiation of both reflexive and affective pain-related behaviors in both sexes., Though sex differences in chronic pain have been consistently described in the literature, their underlying neural mechanisms are poorly understood. Previous work in humans has demonstrated that men and women differentially invoke distinct brain regions and circuits in coping with subjective pain unpleasantness. The goal of the present work was to elucidate the molecular mechanisms in the basolateral nucleus of the amygdala (BLA) that modulate hyperalgesic priming, a pain plasticity model, in males and females. We used plantar incision as the first, priming stimulus and prostaglandin E2 (PGE2) as the second stimulus. We sought to assess whether hyperalgesic priming can be prevented or reversed by pharmacologically manipulating molecular targets in the BLA of male or female mice. We found that administering ZIP, a cell-permeable inhibitor of aPKC, into the BLA attenuated aspects of hyperalgesic priming induced by plantar incision in males and females. However, incision only upregulated PKCζ/PKMζ immunoreactivity in the BLA of male mice, and deficits in hyperalgesic priming were seen only when we restricted our analysis to male Prkcz−/− mice. On the other hand, intra-BLA microinjections of pep2m, a peptide that interferes with the trafficking and function of GluA2-containing AMPA receptors, a downstream target of aPKC, reduced mechanical hypersensitivity after plantar incision and disrupted the development of hyperalgesic priming in both male and female mice. In addition, pep2m treatment reduced facial grimacing and restored aberrant behavioral responses in the sucrose splash test in male and female primed mice. Immunofluorescence results demonstrated upregulation of GluA2 expression in the BLA of male and female primed mice, consistent with pep2m findings. We conclude that, in a model of incision-induced hyperalgesic priming, PKCζ/PKMζ in the BLA is critical for the development of hyperalgesic priming in males, while GluA2 in the BLA is crucial for the expression of both reflexive and affective pain-related behaviors in both male and female mice in this model. Our findings add to a growing body of evidence of sex differences in molecular pain mechanisms in the brain.
- Published
- 2020
20. Intercellular Arc Signaling Regulates Vasodilation
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Jason D. Shepherd, Oswald Steward, Pradipta R. Ray, Nikesh Kunder, Andi Wangzhou, Jane Song, Jamie K. Moy, Theodore J. Price, Paulino Barragán-Iglesias, Tarjani Shukla, Tzu-Fang Lou, Sarah Loerch, Kenneth Hoyt, Salim Megat, June Bryan de la Peña, Lokesh Basavarajappa, and Zachary T. Campbell
- Subjects
Cell type ,Neurogenic inflammation ,Cell signaling ,Arc (protein) ,Chemistry ,Translational regulation ,medicine ,Inflammation ,Translation (biology) ,Extracellular vesicle ,medicine.symptom ,Cell biology - Abstract
Injury responses require communication between different cell types in the skin. Sensory neurons contribute to inflammation and can secrete signaling molecules that affect non-neuronal cells. Despite the pervasive role of translational regulation in nociception, the contribution of activity-dependent protein synthesis to inflammation is not well understood. To address this problem, we examined the landscape of nascent translation in DRG neurons treated with inflammatory mediators using ribosome profiling. We identified the activity-dependent gene, Arc, as a target of privileged translation in vitro and in vivo. Inflammatory cues promote local translation of Arc in the skin. Arc deficient mice display exaggerated paw temperatures and vasodilation in response to an inflammatory challenge. Since Arc has recently been shown to be released from neurons in extracellular vesicles, we hypothesized that intercellular Arc signaling regulates the inflammatory response in skin. We found that the excessive thermal responses and vasodilation observed in Arc defective mice are rescued by injection of Arc-containing extracellular vesicles into the skin. Our findings suggest that activity-dependent production of Arc in afferent fibers regulates neurogenic inflammation through intercellular signaling.
- Published
- 2020
21. Therapeutic opportunities for pain medicines via targeting of specific translation signaling mechanisms
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Theodore J. Price and Salim Megat
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0301 basic medicine ,Pain medicine ,Population ,Neuroscience (miscellaneous) ,Disease ,Article ,lcsh:RC321-571 ,03 medical and health sciences ,Medicine ,education ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,Sensitization ,PI3K/AKT/mTOR pathway ,education.field_of_study ,business.industry ,Chronic pain ,Opioid overdose ,medicine.disease ,3. Good health ,030104 developmental biology ,Anesthesiology and Pain Medicine ,medicine.anatomical_structure ,nervous system ,Nociceptor ,Neurology (clinical) ,business ,Neuroscience - Abstract
As the population of the world ages and as more and more people survive diseases that used to be primary causes of mortality, the incidence of severe chronic pain in most of the world has risen dramatically. This type of pain is very difficult to treat and the opioid overdose epidemic that has become a leading cause of death in the United States and other parts of the world highlights the urgent need to develop new pain therapeutics. A common underlying cause of severe chronic pain is a phenotypic change in pain-sensing neurons in the peripheral nervous system called nociceptors. These neurons play a vital role in detecting potentially injurious stimuli, but when these neurons start to detect very low levels of inflammatory meditators or become spontaneously active, they send spurious pain signals to the brain that are significant drivers of chronic pain. An important question is what drives this phenotypic shift in nociceptors from quiescence under most conditions to sensitization to a broad variety of stimuli and spontaneous activity. The goal of this review is to discuss the critical role that specific translation regulation signaling pathways play in controlling gene expression changes that drive nociceptor sensitization and may underlie the development of spontaneous activity. The focus will be on advances in technologies that allow for identification of such targets and on developments in pharmacology around translation regulation signaling that may yield new pain therapeutics. A key advantage of pharmacological manipulation of these signaling events is that they may reverse phenotypic shifts in nociceptors that drive chronic pain thereby creating the first generation of disease modifying drugs for chronic pain. Keywords: mTOR, MNK, eIF4E, eIF4A, AMPK, Nociceptor, Sensitization
- Published
- 2018
22. A Critical Role for Dopamine D5 Receptors in Pain Chronicity in Male Mice
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Paulino Barragán-Iglesias, Rebecca P. Seal, Stephanie Shiers, Gregory Dussor, Jamie K. Moy, Theodore J. Price, Salim Megat, and Grishma Pradhan
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Male ,0301 basic medicine ,Agonist ,medicine.drug_class ,Receptor expression ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Dopamine ,medicine ,Animals ,Receptors, Dopamine D5 ,Research Articles ,Mice, Knockout ,Sex Characteristics ,Receptors, Dopamine D1 ,General Neuroscience ,Dopaminergic ,Chronic pain ,medicine.disease ,Receptor antagonist ,Mice, Inbred C57BL ,Posterior Horn Cells ,030104 developmental biology ,Hyperalgesia ,Neuropathic pain ,Neuralgia ,Female ,Chronic Pain ,medicine.symptom ,Psychology ,Neuroscience ,030217 neurology & neurosurgery ,medicine.drug - Abstract
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 (DRD5KOmice) to show that carrageenan, interleukin 6, as well as BDNF-induced hyperalgesia and priming are reduced specifically in male mice. These maleDRD5KOmice 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.SIGNIFICANCE STATEMENTPain is the most prominent reason why people seek medical attention, and chronic pain incidence worldwide has been estimated to be as high as 33%. This study provides new insight into how descending dopamine controls pathological pain states. Our work demonstrates that dopaminergic spinal projections are necessary for the maintenance of a chronic pain state in both sexes; however, D5 receptors seem to play a critical role in males whereas females rely more heavily on D1 receptors, an effect that could be explained by sexual dimorphisms in receptor expression levels. Collectively, our work provides new insights into how the dopaminergic system interacts with spinal circuits to promote pain plasticity.
- Published
- 2017
23. The impact of inflammatory mediators on the landscape of nascent translation in the dorsal root ganglion
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Jamie K. Moy, Theodore J. Price, Jane Song, Pradipta R. Ray, June Bryan de la Peña, Tzu-Fang Lou, Oswald Steward, Sarah Loerch, Tarjani Shukla, Salim Megat, Paulino Barragán-Iglesias, Nikesh Kunder, Andi Wanghzou, Kenneth Hoyt, Jason Shepherd, and Lokesh Basavarajappa
- Subjects
Neurogenic inflammation ,Arc (protein) ,business.industry ,P70-S6 Kinase 1 ,Translation (biology) ,Cell biology ,Anesthesiology and Pain Medicine ,Nociception ,medicine.anatomical_structure ,Neurology ,Dorsal root ganglion ,Ribosomal protein s6 ,Translational regulation ,Medicine ,Neurology (clinical) ,business - Abstract
Translational regulation of mRNA permeates nociception. The identities of transcripts subject to translational control are almost entirely unknown. To address this problem, we examine the landscape of nascent translation in DRG neurons treated with inflammatory mediators using ribosome profiling. We identify and validate two targets, the immediate early genes Arc and Fos, as targets of induced translation. Mechanistically, we demonstrate that the ribosomal protein S6 kinase (S6K1) is required for their biosynthesis. Pharmacologic blockade of either S6K1 or Fos attenuates mechanical and thermal hyperalgesia triggered by inflammatory stimuli. Genetic disruption of Arc did not alter pain associated behaviors. However, Arc deficient mice display exaggerated paw temperatures and vasodilation in response to an inflammatory challenge. Since Arc has recently been shown to be released from neurons in extracellular vesicles, we asked if intercellular Arc signaling regulates the inflammatory response in skin. We found that the excessive thermal responses and vasodilation observed in Arc defective mice are rescued by injection of Arc-containing extracellular vesicles into the skin. Collectively, our results suggest that activity-dependent translation in the DRG supports at least two critical functions: neurogenic inflammation (via Arc) and nociception (via Fos).
- Published
- 2021
24. Nociceptor Translational Profiling Reveals the Ragulator-Rag GTPase Complex as a Critical Generator of Neuropathic Pain
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Jamie K. Moy, Theodore J. Price, Patrick M. Dougherty, Gregory Dussor, Nahum Sonenberg, Yan Li, Kevin R. Webster, Pradipta R. Ray, Michael D. Burton, Salim Megat, Robert Y. North, Ayesha Ahmad, Tzu-Fang Lou, Arkady Khoutorsky, Zachary T. Campbell, Andi Wanghzou, Grishma Pradhan, and Paulino Barragán-Iglesias
- Subjects
0301 basic medicine ,Male ,Paclitaxel ,Population ,Mice, Transgenic ,mTORC1 ,Mechanistic Target of Rapamycin Complex 1 ,Protein Serine-Threonine Kinases ,NAV1.8 Voltage-Gated Sodium Channel ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Eukaryotic initiation factor ,Translational regulation ,medicine ,Animals ,education ,Research Articles ,Monomeric GTP-Binding Proteins ,Pain Measurement ,Mice, Knockout ,education.field_of_study ,business.industry ,General Neuroscience ,Gene Expression Profiling ,EIF4E ,Chronic pain ,Nociceptors ,Translation (biology) ,medicine.disease ,Antineoplastic Agents, Phytogenic ,030104 developmental biology ,Eukaryotic Initiation Factor-4E ,Neuropathic pain ,Neuralgia ,Female ,business ,Neuroscience ,Ribosomes ,030217 neurology & neurosurgery ,Signal Transduction - Abstract
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 inScn10a-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, a GTPase 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.SIGNIFICANCE STATEMENTNeuropathic pain affects up to 10% of the population, but its underlying mechanisms are incompletely understood, leading to poor treatment outcomes. We used translating ribosome affinity purification technology to create a comprehensive translational profile of DRG nociceptors in naive mice and at the peak of neuropathic pain induced by paclitaxel treatment. We reveal new insight into how mechanistic target of rapamycin complex 1 is activated in neuropathic pain pointing to a key role of MNK1-eIF4E-mediated translation of a complex of mRNAs that control mechanistic target of rapamycin complex 1 signaling at the surface of the lysosome. We validate this finding using genetic and pharmacological techniques. Our work strongly suggests that MNK1-eIF4E signaling drives CIPN and that a drug in human clinical trials, eFT508, may be a new therapeutic for neuropathic pain.
- Published
- 2019
25. A Dual Noradrenergic Mechanism for the Relief of Neuropathic Allodynia by the Antidepressant Drugs Duloxetine and Amitriptyline
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Ralf Gilsbach, Laurent Nexon, Xavier Wurtz, Dorothée Daniel, Salim Megat, Carl Ernst, Lauriane-Elisabeth Joganah, Pierre-Eric Lutz, Vincent Lelievre, Ipek Yalcin, Jean-François Théroux, Michel Barrot, Rhian Alice Ceredig, Dominique Massotte, Yannick Goumon, Virginie Chavant, Mélanie Kremer, Gustavo Turecki, Adrien Lacaud, Eric Salvat, Institut des Neurosciences Cellulaires et Intégratives (INCI), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Department of Psychiatry [Montréal], McGill University, McGill University = Université McGill [Montréal, Canada], Lutz, Pierre-Eric, Douglas Mental Health University Institute [Montréal], Centre d'Etude et de Traitement de la Douleur [HUS, Strasbourg] (CETD), Les Hôpitaux Universitaires de Strasbourg (HUS), and University of Freiburg [Freiburg]
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Male ,0301 basic medicine ,Nervous system ,neuropathic pain ,amitriptyline ,Pharmacology ,Mice ,Norepinephrine ,chemistry.chemical_compound ,0302 clinical medicine ,TLR2 ,Amitriptyline ,Research Articles ,Mice, Knockout ,General Neuroscience ,duloxetine ,Middle Aged ,Antidepressive Agents ,3. Good health ,Allodynia ,medicine.anatomical_structure ,antidepressants ,Neuropathic pain ,Antidepressant ,Female ,[SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC] ,medicine.symptom ,medicine.drug ,Adult ,Receptor, Adenosine A2A ,medicine.drug_class ,Tricyclic antidepressant ,Duloxetine Hydrochloride ,03 medical and health sciences ,medicine ,Animals ,Humans ,Pain Management ,Duloxetine ,[SDV.NEU] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC] ,Aged ,business.industry ,Mice, Inbred C57BL ,030104 developmental biology ,chemistry ,Opioid ,TNF-α ,Neuralgia ,business ,030217 neurology & neurosurgery - Abstract
In addition to treating depression, antidepressant drugs are also a first-line treatment for neuropathic pain, which is pain secondary to lesion or pathology of the nervous system. Despite the widespread use of these drugs, the mechanism underlying their therapeutic action in this pain context remains partly elusive. The present study combined data collected in male and female mice from a model of neuropathic pain and data from the clinical setting to understand how antidepressant drugs act. We show two distinct mechanisms by which the selective inhibitor of serotonin and noradrenaline reuptake duloxetine and the tricyclic antidepressant amitriptyline relieve neuropathic allodynia. One of these mechanisms is acute, central, and requires descending noradrenergic inhibitory controls and α2Aadrenoceptors, as well as the mu and delta opioid receptors. The second mechanism is delayed, peripheral, and requires noradrenaline from peripheral sympathetic endings and β2adrenoceptors, as well as the delta opioid receptors. We then conducted a transcriptomic analysis in dorsal root ganglia, which suggested that the peripheral component of duloxetine action involves the inhibition of neuroimmune mechanisms accompanying nerve injury, including the downregulation of the TNF-α–NF-κB signaling pathway. Accordingly, immunotherapies against either TNF-α or Toll-like receptor 2 (TLR2) provided allodynia relief. We also compared duloxetine plasma levels in the animal model and in patients and we observed that patients' drug concentrations were compatible with those measured in animals under chronic treatment involving the peripheral mechanism. Our study highlights a peripheral neuroimmune component of antidepressant drugs that is relevant to their delayed therapeutic action against neuropathic pain.SIGNIFICANCE STATEMENTIn addition to treating depression, antidepressant drugs are also a first-line treatment for neuropathic pain, which is pain secondary to lesion or pathology of the nervous system. However, the mechanism by which antidepressant drugs can relieve neuropathic pain remained in part elusive. Indeed, preclinical studies led to contradictions concerning the anatomical and molecular substrates of this action. In the present work, we overcame these apparent contradictions by highlighting the existence of two independent mechanisms. One is rapid and centrally mediated by descending controls from the brain to the spinal cord and the other is delayed, peripheral, and relies on the anti-neuroimmune action of chronic antidepressant treatment.
- Published
- 2018
26. Nociceptor translational profiling reveals the RagA-mTORC1 network as a critical generator of neuropathic pain
- Author
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Pradipta R. Ray, Jamie K. Moy, Theodore J. Price, Robert Y. North, Grishma Pradhan, Tzu-Fang Lou, Kevin R. Webster, Salim Megat, Zachary T. Campbell, Gregory Dussor, Yan Li, Nahum Sonenberg, Andi Wangzhou, Patrick M. Dougherty, Ayesha Ahmad, Arkady Khoutorsky, and Paulino Barragán-Iglesias
- Subjects
0301 basic medicine ,business.industry ,Mechanism (biology) ,EIF4E ,Translation (biology) ,mTORC1 ,3. Good health ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,030220 oncology & carcinogenesis ,Neuropathic pain ,Nociceptor ,Medicine ,Phosphorylation ,Signal transduction ,business ,Neuroscience - Abstract
Pain sensing neurons, nociceptors, are key drivers of neuropathic pain. We used translating ribosome affinity purification (TRAP) to comprehensively characterize up-and down-regulated mRNA translation in Scn10a-positive nociceptors in chemotherapy-induced neuropathic pain. We provide evidence that an underlying mechanism driving these changes in gene expression is a sustained mTORC1 activation driven by MNK1-eIF4E signaling. RagA, a GTPase controlling mTORC1 activity, is identified as a novel target of MNK1-eIF4E signaling, demonstrating a new link between these distinct signaling pathways. Neuropathic pain and RagA translation are strongly attenuated by genetic ablation of eIF4E phosphorylation, MNK1 elimination or treatment with the MNK inhibitor eFT508. We reveal a novel translational circuit for the genesis of neuropathic pain with important implications for next generation neuropathic pain therapeutics.One Sentence SummaryCell-specific sequencing of translating mRNAs elucidates signaling pathology that can be targeted to reverse neuropathic pain
- Published
- 2018
27. Inhibition of Poly(A)-binding protein with a synthetic RNA mimic reduces pain sensitization in mice
- Author
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Tzu-Fang Lou, Vandita D Bhat, Salim Megat, Paulino Barragán-Iglesias, Michael D. Burton, Theodore J. Price, and Zachary T. Campbell
- Subjects
0301 basic medicine ,Science ,Pain ,General Physics and Astronomy ,RNA-binding protein ,Poly(A)-Binding Proteins ,Article ,General Biochemistry, Genetics and Molecular Biology ,Nociceptive Pain ,Mice ,03 medical and health sciences ,Eukaryotic initiation factor 4F ,0302 clinical medicine ,Eukaryotic translation ,Cell Line, Tumor ,Ganglia, Spinal ,Poly(A)-binding protein ,Protein biosynthesis ,Animals ,Humans ,lcsh:Science ,Cells, Cultured ,Pain Measurement ,Neurons ,Messenger RNA ,Multidisciplinary ,biology ,Chemistry ,RNA ,Translation (biology) ,General Chemistry ,3. Good health ,Cell biology ,030104 developmental biology ,biology.protein ,lcsh:Q ,Poly A ,030217 neurology & neurosurgery ,Protein Binding - Abstract
Nociceptors rely on cap-dependent translation to rapidly induce protein synthesis in response to pro-inflammatory signals. Comparatively little is known regarding the role of the regulatory factors bound to the 3′ end of mRNA in nociceptor sensitization. Poly(A)-binding protein (PABP) stimulates translation initiation by bridging the Poly(A) tail to the eukaryotic initiation factor 4F complex associated with the mRNA cap. Here, we use unbiased assessment of PABP binding specificity to generate a chemically modified RNA-based competitive inhibitor of PABP. The resulting RNA mimic, which we designated as the Poly(A) SPOT-ON, is more stable than unmodified RNA and binds PABP with high affinity and selectivity in vitro. We show that injection of the Poly(A) SPOT-ON at the site of an injury can attenuate behavioral response to pain. Collectively, these results suggest that PABP is integral for nociceptive plasticity. The general strategy described here provides a broad new source of mechanism-based inhibitors for RNA-binding proteins and is applicable for in vivo studies., Poly(A)-binding protein (PABP) is an RNA binding protein with translation function. Here, Barragán-Iglesias and colleagues devise an RNA mimic that inhibits PABP activity, and show that inhibitors can reduce animal’s pain response in vivo when injected locally.
- Published
- 2018
28. κ-opioid receptors are not necessary for the antidepressant treatment of neuropathic pain
- Author
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Claire Gaveriaux-Ruff, Brigitte L. Kieffer, Michel Barrot, Ipek Yalcin, Marie-José Freund-Mercier, Salim Megat, Stephane Doridot, and Yohann Bohren
- Subjects
Pharmacology ,chemistry.chemical_classification ,chemistry ,Opioid ,business.industry ,Neuropathic pain ,Medicine ,Antidepressant ,business ,Receptor ,Tricyclic ,medicine.drug - Abstract
Background and Purpose Tricyclic antidepressants are used clinically as first-line treatments for neuropathic pain. Opioid receptors participate in this pain-relieving action, and preclinical studies in receptor-deficient mice have highlighted a critical role for δ-, but not μ-opioid receptors. In this study, we investigated whether κ-opioid (KOP) receptors have a role in the antiallodynic action of tricyclic antidepressants.
- Published
- 2014
29. The landscape of nascent protein synthesis in the DRG at single codon resolution
- Author
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Pradipta R. Ray, P. Barragan Iglesias, Zachary T. Campbell, Jamie K. Moy, Theodore J. Price, Andi Wangzhou, Nikesh Kunder, Salim Megat, Tzu-Fang Lou, and Tarjani Shukla
- Subjects
Anesthesiology and Pain Medicine ,Neurology ,business.industry ,Resolution (electron density) ,Medicine ,Neurology (clinical) ,Computational biology ,Translocon ,business - Published
- 2018
30. Antidepressants suppress neuropathic pain by a peripheral β2-adrenoceptor mediated anti-TNFα mechanism
- Author
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Luc-Henri Tessier, Michel Barrot, Lutz Hein, Sylvie Fournel, Hugues Petitjean, Salim Megat, Yohann Bohren, Mélanie Kremer, Dorothée Daniel, Marie-José Freund-Mercier, Sylvain Hugel, Rémy Schlichter, Ipek Yalcin, Institut des Neurosciences Cellulaires et Intégratives (INCI), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Benephyt, Immunologie et chimie thérapeutiques (ICT), and Cancéropôle du Grand Est-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Male ,[SDV]Life Sciences [q-bio] ,Antidepressant ,Adrenoceptor ,Pharmacology ,Antidepressive Agents, Tricyclic ,Receptors, Tumor Necrosis Factor ,Reuptake ,Etanercept ,Mice ,Norepinephrine ,0302 clinical medicine ,Ganglia, Spinal ,Dorsal root ganglia ,ComputingMilieux_MISCELLANEOUS ,Pain Measurement ,0303 health sciences ,Anti-Inflammatory Agents, Non-Steroidal ,Antibodies, Monoclonal ,3. Good health ,Allodynia ,Neurology ,Neuropathic pain ,medicine.symptom ,medicine.drug ,Agonist ,medicine.drug_class ,Tricyclic antidepressant ,Nortriptyline ,lcsh:RC321-571 ,Lesion ,03 medical and health sciences ,medicine ,Animals ,Adrenergic beta-2 Receptor Agonists ,Cytokine ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,030304 developmental biology ,business.industry ,Tumor Necrosis Factor-alpha ,Infliximab ,Mice, Inbred C57BL ,Satellite ,Immunoglobulin G ,Neuralgia ,Receptors, Adrenergic, beta-2 ,business ,030217 neurology & neurosurgery - Abstract
Neuropathic pain is pain arising as a direct consequence of a lesion or disease affecting the somatosensory system. It is usually chronic and challenging to treat. Some antidepressants are first-line pharmacological treatments for neuropathic pain. The noradrenaline that is recruited by the action of the antidepressants on reuptake transporters has been proposed to act through β2-adrenoceptors (β2-ARs) to lead to the observed therapeutic effect. However, the complex downstream mechanism mediating this action remained to be identified. In this study, we demonstrate in a mouse model of neuropathic pain that an antidepressant's effect on neuropathic allodynia involves the peripheral nervous system and the inhibition of cytokine tumor necrosis factor α (TNFα) production. The antiallodynic action of nortriptyline is indeed lost after peripheral sympathectomy, but not after lesion of central descending noradrenergic pathways. More particularly, we report that antidepressant-recruited noradrenaline acts, within dorsal root ganglia, on β2-ARs expressed by non-neuronal satellite cells. This stimulation of β2-ARs decreases the neuropathy-induced production of membrane-bound TNFα, resulting in relief of neuropathic allodynia. This indirect anti-TNFα action was observed with the tricyclic antidepressant nortriptyline, the selective serotonin and noradrenaline reuptake inhibitor venlafaxine and the β2-AR agonist terbutaline. Our data revealed an original therapeutic mechanism that may open novel research avenues for the management of painful peripheral neuropathies.
- Published
- 2013
31. Neuroligin 2 regulates spinal GABAergic plasticity in hyperalgesic priming, a model of the transition from acute to chronic pain
- Author
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Jamie K. Moy, Theodore J. Price, Salim Megat, Marina N. Asiedu, Ji Young V. Kim, Josef Vagner, and Galo L. Mejia
- Subjects
0301 basic medicine ,Pain Threshold ,Cell Adhesion Molecules, Neuronal ,Synaptogenesis ,Neuroligin ,Nerve Tissue Proteins ,Inhibitory postsynaptic potential ,Article ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Neurotrophic factors ,Neuroplasticity ,medicine ,Animals ,GABAergic Neurons ,Mice, Inbred ICR ,Neuronal Plasticity ,GABAA receptor ,Brain-Derived Neurotrophic Factor ,Chronic pain ,medicine.disease ,Acute Pain ,Disease Models, Animal ,030104 developmental biology ,Anesthesiology and Pain Medicine ,Nociception ,Neurology ,Spinal Cord ,Hyperalgesia ,Neurology (clinical) ,Chronic Pain ,Psychology ,Neuroscience ,030217 neurology & neurosurgery - Abstract
Plasticity in inhibitory receptors, neurotransmission, and networks is an important mechanism for nociceptive signal amplification in the spinal dorsal horn. We studied potential changes in GABAergic pharmacology and its underlying mechanisms in hyperalgesic priming, a model of the transition from acute to chronic pain. We find that while GABAA agonists and positive allosteric modulators reduce mechanical hypersensitivity to an acute insult, they fail to do so during the maintenance phase of hyperalgesic priming. In contrast, GABAA antagonism promotes antinociception and a reduction in facial grimacing after the transition to a chronic pain state. During the maintenance phase of hyperalgesic priming, we observed increased neuroligin (nlgn) 2 expression in the spinal dorsal horn. This protein increase was associated with an increase in nlgn2A splice variant mRNA, which promotes inhibitory synaptogenesis. Disruption of nlgn2 function with the peptide inhibitor, neurolide 2, produced mechanical hypersensitivity in naive mice but reversed hyperalgesic priming in mice previously exposed to brain-derived neurotrophic factor. Neurolide 2 treatment also reverses the change in polarity in GABAergic pharmacology observed in the maintenance of hyperalgesic priming. We propose that increased nlgn2 expression is associated with hyperalgesic priming where it promotes dysregulation of inhibitory networks. Our observations reveal new mechanisms involved in the spinal maintenance of a pain plasticity and further suggest that disinhibitory mechanisms are central features of neuroplasticity in the spinal dorsal horn.
- Published
- 2016
32. The Sciatic Nerve Cuffing Model of Neuropathic Pain in Mice
- Author
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Florent Barthas, Salim Megat, Elisabeth Waltisperger, Mélanie Kremer, Ipek Yalcin, Eric Salvat, and Michel Barrot
- Subjects
Male ,General Chemical Engineering ,Central nervous system ,Somatosensory system ,General Biochemistry, Genetics and Molecular Biology ,Lesion ,Mice ,Medicine ,Animals ,pain ,mouse ,sciatic ,allodynia ,neuropathic pain ,Issue 89 ,model ,General Immunology and Microbiology ,business.industry ,General Neuroscience ,Sciatic Nerve ,Mice, Inbred C57BL ,Disease Models, Animal ,Nociception ,Allodynia ,medicine.anatomical_structure ,Hyperalgesia ,Anesthesia ,Peripheral nerve injury ,Neuropathic pain ,Neuralgia ,Sciatic nerve ,medicine.symptom ,cuff ,Sciatic Neuropathy ,business ,Neuroscience ,von Frey - Abstract
Neuropathic pain arises as a consequence of a lesion or a disease affecting the somatosensory system. This syndrome results from maladaptive changes in injured sensory neurons and along the entire nociceptive pathway within the central nervous system. It is usually chronic and challenging to treat. In order to study neuropathic pain and its treatments, different models have been developed in rodents. These models derive from known etiologies, thus reproducing peripheral nerve injuries, central injuries, and metabolic-, infectious- or chemotherapy-related neuropathies. Murine models of peripheral nerve injury often target the sciatic nerve which is easy to access and allows nociceptive tests on the hind paw. These models rely on a compression and/or a section. Here, the detailed surgery procedure for the "cuff model" of neuropathic pain in mice is described. In this model, a cuff of PE-20 polyethylene tubing of standardized length (2 mm) is unilaterally implanted around the main branch of the sciatic nerve. It induces a long-lasting mechanical allodynia, i.e., a nociceptive response to a normally non-nociceptive stimulus that can be evaluated by using von Frey filaments. Besides the detailed surgery and testing procedures, the interest of this model for the study of neuropathic pain mechanism, for the study of neuropathic pain sensory and anxiodepressive aspects, and for the study of neuropathic pain treatments are also discussed.
- Published
- 2014
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