1 2565 119 EPIGENETICS INVOLVEMENT IN OXALIPLATIN-INDUCED POTASSIUM CHANNEL TRANSCRIPTIONAL DOWNREGULATION AND HYPERSENSITIVITY. PERIPHERAL NEUROPATHY IS THE MOST FREQUENT DOSE-LIMITING ADVERSE EFFECT OF OXALIPLATIN. ACUTE PAIN SYMPTOMS THAT ARE INDUCED OR EXACERBATED BY COLD OCCUR IN ALMOST ALL PATIENTS IMMEDIATELY FOLLOWING THE FIRST INFUSIONS. EVIDENCE HAS SHOWN THAT OXALIPLATIN CAUSES ION CHANNEL EXPRESSION MODULATIONS IN DORSAL ROOT GANGLIA NEURONS, WHICH ARE THOUGHT TO CONTRIBUTE TO PERIPHERAL HYPERSENSITIVITY. MOST DYSREGULATED GENES ENCODE ION CHANNELS INVOLVED IN COLD AND MECHANICAL PERCEPTION, NOTEWORTHY MEMBERS OF A SUB-GROUP OF POTASSIUM CHANNELS OF THE K2P FAMILY, TREK AND TRAAK. DOWNREGULATION OF THESE K2P CHANNELS HAS BEEN IDENTIFIED AS AN IMPORTANT TUNER OF ACUTE OXALIPLATIN-INDUCED HYPERSENSITIVITY. WE INVESTIGATED THE MOLECULAR MECHANISMS UNDERLYING THIS PERIPHERAL DYSREGULATION IN A MURINE MODEL OF NEUROPATHIC PAIN TRIGGERED BY A SINGLE OXALIPLATIN ADMINISTRATION. WE FOUND THAT OXALIPLATIN-MEDIATED TREK-TRAAK DOWNREGULATION, AS WELL AS DOWNREGULATION OF OTHER K(+) CHANNELS OF THE K2P AND KV FAMILIES, INVOLVES A TRANSCRIPTION FACTOR KNOWN AS THE NEURON-RESTRICTIVE SILENCER FACTOR (NRSF) AND ITS EPIGENETIC CO-REPRESSORS HISTONE DEACETYLASES (HDACS). NRSF KNOCKDOWN WAS ABLE TO PREVENT MOST OF THESE K(+) CHANNEL MRNA DOWNREGULATION IN MICE DORSAL ROOT GANGLION NEURONS AS WELL AS OXALIPLATIN-INDUCED ACUTE COLD AND MECHANICAL HYPERSENSITIVITY. INTERESTINGLY, PHARMACOLOGICAL INHIBITION OF CLASS I HDAC REPRODUCES THE ANTINOCICEPTIVE EFFECTS OF NRSF KNOCKDOWN AND LEADS TO AN INCREASED K(+) CHANNEL EXPRESSION IN OXALIPLATIN-TREATED MICE. 2021 2 4637 34 NEURON-RESTRICTIVE SILENCER FACTOR CAUSES EPIGENETIC SILENCING OF KV4.3 GENE AFTER PERIPHERAL NERVE INJURY. PERIPHERAL NERVE INJURY CAUSES A VARIETY OF ALTERATIONS IN PAIN-RELATED GENE EXPRESSION IN PRIMARY AFFERENT, WHICH UNDERLIE THE NEURONAL PLASTICITY IN NEUROPATHIC PAIN. ONE OF THE CHARACTERISTIC ALTERATIONS IS A LONG-LASTING DOWNREGULATION OF VOLTAGE-GATED POTASSIUM (K(V)) CHANNEL, INCLUDING K(V)4.3, IN THE DORSAL ROOT GANGLION (DRG). THE PRESENT STUDY SHOWED THAT NERVE INJURY REDUCES THE MESSENGER RNA (MRNA) EXPRESSION LEVEL OF K(V)4.3 GENE, WHICH CONTAINS A CONSERVED NEURON-RESTRICTIVE SILENCER ELEMENT (NRSE), A BINDING SITE FOR NEURON-RESTRICTIVE SILENCER FACTOR (NRSF). MOREOVER, WE FOUND THAT INJURY CAUSES AN INCREASE IN DIRECT NRSF BINDING TO K(V)4.3-NRSE IN THE DRG, USING CHROMATIN IMMUNOPRECIPITATION (CHIP) ASSAY. CHIP ASSAY FURTHER REVEALED THAT ACETYLATION OF HISTONE H4, BUT NOT H3, AT K(V)4.3-NRSE IS MARKEDLY REDUCED AT DAY 7 POST-INJURY. FINALLY, THE INJURY-INDUCED K(V)4.3 DOWNREGULATION WAS SIGNIFICANTLY BLOCKED BY ANTISENSE-KNOCKDOWN OF NRSF. TAKEN TOGETHER, THESE DATA SUGGEST THAT NERVE INJURY CAUSES AN EPIGENETIC SILENCING OF K(V)4.3 GENE MEDIATED THROUGH TRANSCRIPTIONAL SUPPRESSOR NRSF IN THE DRG. 2010 3 4861 34 ORGANIC ANION TRANSPORTER 1 IS AN HDAC4-REGULATED MEDIATOR OF NOCICEPTIVE HYPERSENSITIVITY IN MICE. PERSISTENT PAIN IS SUSTAINED BY MALADAPTIVE CHANGES IN GENE TRANSCRIPTION RESULTING IN ALTERED FUNCTION OF THE RELEVANT CIRCUITS; THERAPIES ARE STILL UNSATISFACTORY. THE EPIGENETIC MECHANISMS AND AFFECTED GENES LINKING NOCICEPTIVE ACTIVITY TO TRANSCRIPTIONAL CHANGES AND PATHOLOGICAL SENSITIVITY ARE UNCLEAR. HERE, WE FOUND THAT, AMONG SEVERAL HISTONE DEACETYLASES (HDACS), SYNAPTIC ACTIVITY SPECIFICALLY AFFECTS HDAC4 IN MURINE SPINAL CORD DORSAL HORN NEURONS. NOXIOUS STIMULI THAT INDUCE LONG-LASTING INFLAMMATORY HYPERSENSITIVITY CAUSE NUCLEAR EXPORT AND INACTIVATION OF HDAC4. THE DEVELOPMENT OF INFLAMMATION-ASSOCIATED MECHANICAL HYPERSENSITIVITY, BUT NEITHER ACUTE NOR BASAL SENSITIVITY, IS IMPAIRED BY THE EXPRESSION OF A CONSTITUTIVELY NUCLEAR LOCALIZED HDAC4 MUTANT. NEXT GENERATION RNA-SEQUENCING REVEALED AN HDAC4-REGULATED GENE PROGRAM COMPRISING MEDIATORS OF SENSITIZATION INCLUDING THE ORGANIC ANION TRANSPORTER OAT1, KNOWN FOR ITS RENAL TRANSPORT FUNCTION. USING PHARMACOLOGICAL AND MOLECULAR TOOLS TO MODULATE OAT1 ACTIVITY OR EXPRESSION, WE CAUSALLY LINK OAT1 TO PERSISTENT INFLAMMATORY HYPERSENSITIVITY IN MICE. THUS, HDAC4 IS A KEY EPIGENETIC REGULATOR THAT TRANSLATES NOCICEPTIVE ACTIVITY INTO SENSITIZATION BY REGULATING OAT1, WHICH IS A POTENTIAL TARGET FOR PAIN-RELIEVING THERAPIES. 2022 4 2470 36 EPIGENETIC TRANSCRIPTIONAL ACTIVATION OF MONOCYTE CHEMOTACTIC PROTEIN 3 CONTRIBUTES TO LONG-LASTING NEUROPATHIC PAIN. A MULTIPLEX ANALYSIS FOR PROFILING THE EXPRESSION OF CANDIDATE GENES ALONG WITH EPIGENETIC MODIFICATION MAY LEAD TO A BETTER UNDERSTANDING OF THE COMPLEX MACHINERY OF NEUROPATHIC PAIN. IN THE PRESENT STUDY, WE FOUND THAT PARTIAL SCIATIC NERVE LIGATION MOST REMARKABLY INCREASED THE EXPRESSION OF MONOCYTE CHEMOTACTIC PROTEIN 3 (MCP-3, KNOWN AS CCL7) A TOTAL OF 33 541 GENES IN THE SPINAL CORD, WHICH LASTED FOR 4 WEEKS. THIS INCREASE IN MCP-3 GENE TRANSCRIPTION WAS ACCOMPANIED BY THE DECREASED TRIMETHYLATION OF HISTONE H3 AT LYS27 AT THE MCP-3 PROMOTER. THE INCREASED MCP-3 EXPRESSION ASSOCIATED WITH ITS EPIGENETIC MODIFICATION OBSERVED IN THE SPINAL CORD WAS ALMOST ABOLISHED IN INTERLEUKIN 6 KNOCKOUT MICE WITH PARTIAL SCIATIC NERVE LIGATION. CONSISTENT WITH THESE FINDINGS, A SINGLE INTRATHECAL INJECTION OF RECOMBINANT PROTEINS OF INTERLEUKIN 6 SIGNIFICANTLY INCREASED MCP-3 MESSENGER RNA WITH A DECREASE IN THE LEVEL OF LYS27 TRIMETHYLATION OF HISTONE H3 AT THE MCP-3 PROMOTER IN THE SPINAL CORD OF MICE. FURTHERMORE, DELETION OF THE C-C CHEMOKINE RECEPTOR TYPE 2 (CCR2) GENE, WHICH ENCODES A RECEPTOR FOR MCP-3, FAILED TO AFFECT THE ACCELERATION OF MCP-3 EXPRESSION IN THE SPINAL CORD AFTER PARTIAL SCIATIC NERVE LIGATION. A ROBUST INCREASE IN MCP-3 PROTEIN, WHICH LASTED FOR UP TO 2 WEEKS AFTER SURGERY, IN THE DORSAL HORN OF THE SPINAL CORD OF MICE WITH PARTIAL SCIATIC NERVE LIGATION WAS SEEN MOSTLY IN ASTROCYTES, BUT NOT MICROGLIA OR NEURONS. ON THE OTHER HAND, THE INCREASES IN BOTH MICROGLIA AND ASTROCYTES IN THE SPINAL CORD BY PARTIAL SCIATIC NERVE LIGATION WERE MOSTLY ABOLISHED IN INTERLEUKIN 6 KNOCKOUT MICE. MOREOVER, THIS INCREASE IN MICROGLIA WAS ALMOST ABOLISHED BY CCR2 GENE DELETION, WHEREAS THE INCREASE IN ASTROCYTES WAS NOT AFFECTED IN NERVE-LIGATED MICE THAT LACKED THE CCR2 GENE. WE ALSO FOUND THAT EITHER IN VIVO OR IN VITRO TREATMENT WITH MCP-3 CAUSED ROBUST MICROGLIA ACTIVATION. UNDER THESE CONDITIONS, INTRATHECAL ADMINISTRATION OF MCP-3 ANTIBODY SUPPRESSED THE INCREASE IN MICROGLIA WITHIN THE MOUSE SPINAL CORD AND NEUROPATHIC PAIN-LIKE BEHAVIOURS AFTER NERVE INJURY. WITH THE USE OF A FUNCTIONAL MAGNETIC RESONANCE IMAGING ANALYSIS, WE DEMONSTRATED THAT A SINGLE INTRATHECAL INJECTION OF MCP-3 INDUCED DRAMATIC INCREASES IN SIGNAL INTENSITY IN PAIN-RELATED BRAIN REGIONS. THESE FINDINGS SUGGEST THAT INCREASED MCP-3 EXPRESSION ASSOCIATED WITH INTERLEUKIN 6 DEPENDENT EPIGENETIC MODIFICATION AT THE MCP-3 PROMOTER AFTER NERVE INJURY, MOSTLY IN SPINAL ASTROCYTES, MAY SERVE TO FACILITATE ASTROCYTE-MICROGLIA INTERACTION IN THE SPINAL CORD AND COULD PLAY A CRITICAL ROLE IN THE NEUROPATHIC PAIN-LIKE STATE. 2013 5 657 32 BLOCKING THE SPINAL FBXO3/CARM1/K(+) CHANNEL EPIGENETIC SILENCING PATHWAY AS A STRATEGY FOR NEUROPATHIC PAIN RELIEF. MANY EPIGENETIC REGULATORS ARE INVOLVED IN PAIN-ASSOCIATED SPINAL PLASTICITY. COACTIVATOR-ASSOCIATED ARGININE METHYLTRANSFERASE 1 (CARM1), AN EPIGENETIC REGULATOR OF HISTONE ARGININE METHYLATION, IS A HIGHLY INTERESTING TARGET IN NEUROPLASTICITY. HOWEVER, ITS POTENTIAL CONTRIBUTION TO SPINAL PLASTICITY-ASSOCIATED NEUROPATHIC PAIN DEVELOPMENT REMAINS POORLY EXPLORED. HERE, WE REPORT THAT NERVE INJURY DECREASED THE EXPRESSION OF SPINAL CARM1 AND INDUCED ALLODYNIA. MOREOVER, DECREASING SPINAL CARM1 EXPRESSION BY FBXO3-MEDIATED CARM1 UBIQUITINATION PROMOTED H3R17ME2 DECREMENT AT THE K(+) CHANNEL PROMOTER, THEREBY CAUSING K(+) CHANNEL EPIGENETIC SILENCING AND THE DEVELOPMENT OF NEUROPATHIC PAIN. REMARKABLY, IN NAIVE RATS, DECREASING SPINAL CARM1 USING CARM1 SIRNA OR A CARM1 INHIBITOR RESULTED IN SIMILAR EPIGENETIC SIGNALING AND ALLODYNIA. FURTHERMORE, INTRATHECAL ADMINISTRATION OF BC-1215 (A NOVEL FBXO3 INHIBITOR) PREVENTED CARM1 UBIQUITINATION TO BLOCK K(+) CHANNEL GENE SILENCING AND AMELIORATE ALLODYNIA AFTER NERVE INJURY. COLLECTIVELY, THE RESULTS REVEAL THAT THIS NEWLY IDENTIFIED SPINAL FBXO3-CARM1-K(+) CHANNEL GENE FUNCTIONAL AXIS PROMOTES NEUROPATHIC PAIN. THESE FINDINGS PROVIDE ESSENTIAL INSIGHTS THAT WILL AID IN THE DEVELOPMENT OF MORE EFFICIENT AND SPECIFIC THERAPIES AGAINST NEUROPATHIC PAIN. 2021 6 4614 33 NERVE EXCITABILITY AND NEUROPATHIC PAIN IS REDUCED BY BET PROTEIN INHIBITION AFTER SPARED NERVE INJURY. NEUROPATHIC PAIN IS A COMMON DISABILITY PRODUCED BY ENHANCED NEURONAL EXCITABILITY AFTER NERVOUS SYSTEM INJURY. THE PATHOPHYSIOLOGICAL CHANGES THAT UNDERLIE THE GENERATION AND MAINTENANCE OF NEUROPATHIC PAIN REQUIRE MODIFICATIONS OF TRANSCRIPTIONAL PROGRAMS. IN PARTICULAR, THERE IS AN INDUCTION OF PRO-INFLAMMATORY NEUROMODULATORS LEVELS, AND CHANGES IN THE EXPRESSION OF ION CHANNELS AND OTHER FACTORS INTERVENING IN THE DETERMINATION OF THE MEMBRANE POTENTIAL IN NEURONAL CELLS. WE HAVE PREVIOUSLY FOUND THAT INHIBITION OF THE BET PROTEINS EPIGENETIC READERS REDUCED NEUROINFLAMMATION AFTER SPINAL CORD INJURY. WITHIN THE PRESENT STUDY WE AIMED TO DETERMINE IF BET PROTEIN INHIBITION MAY ALSO AFFECT NEUROINFLAMMATION AFTER A PERIPHERAL NERVE INJURY, AND IF THIS WOULD BENEFICIALLY ALTER NEURONAL EXCITABILITY AND NEUROPATHIC PAIN. FOR THIS PURPOSE, C57BL/6 FEMALE MICE UNDERWENT SPARED NERVE INJURY (SNI), AND WERE TREATED WITH THE BET INHIBITOR JQ1, OR VEHICLE. ELECTROPHYSIOLOGICAL AND ALGESIMETRY TESTS WERE PERFORMED ON THESE MICE. WE ALSO DETERMINED THE EFFECTS OF JQ1 TREATMENT AFTER INJURY ON NEUROINFLAMMATION, AND THE EXPRESSION OF NEURONAL COMPONENTS IMPORTANT FOR THE MAINTENANCE OF AXON MEMBRANE POTENTIAL. WE FOUND THAT TREATMENT WITH JQ1 AFFECTED NEURONAL EXCITABILITY AND MECHANICAL HYPERALGESIA AFTER SNI IN MICE. BET PROTEIN INHIBITION REGULATED CYTOKINE EXPRESSION AND REDUCED MICROGLIAL REACTIVITY AFTER INJURY. IN ADDITION, JQ1 TREATMENT ALTERED THE EXPRESSION OF SCN3A, SCN9A, KCNA1, KCNQ2, KCNQ3, HCN1 AND HCN2 ION CHANNELS, AS WELL AS THE EXPRESSION OF THE NA(+)/K(+) ATPASE PUMP SUBUNITS. IN CONCLUSION, BOTH, ALTERATION OF INFLAMMATION, AND NEURONAL TRANSCRIPTION, COULD BE THE RESPONSIBLE EPIGENETIC MECHANISMS FOR THE REDUCTION OF EXCITABILITY AND HYPERALGESIA OBSERVED AFTER BET INHIBITION. INHIBITION OF BET PROTEINS IS A PROMISING THERAPY FOR REDUCING NEUROPATHIC PAIN AFTER NEURAL INJURY. PERSPECTIVE: NEUROPATHIC PAIN IS A COMMON DISABILITY PRODUCED BY ENHANCED NEURONAL EXCITABILITY AFTER NERVOUS SYSTEM INJURY. THE UNDERLYING PATHOPHYSIOLOGICAL CHANGES REQUIRE MODIFICATIONS OF TRANSCRIPTIONAL PROGRAMS. THIS STUDY NOTES THAT INHIBITION OF BET PROTEINS IS A PROMISING THERAPY FOR REDUCING NEUROPATHIC PAIN AFTER NEURAL INJURY. 2021 7 3194 33 HDAC INHIBITORS ATTENUATE THE DEVELOPMENT OF HYPERSENSITIVITY IN MODELS OF NEUROPATHIC PAIN. HISTONE DEACETYLASE INHIBITORS (HDACIS) INTERFERE WITH THE EPIGENETIC PROCESS OF HISTONE ACETYLATION AND ARE KNOWN TO HAVE ANALGESIC PROPERTIES IN MODELS OF CHRONIC INFLAMMATORY PAIN. THE AIM OF THIS STUDY WAS TO DETERMINE WHETHER THESE COMPOUNDS COULD ALSO AFFECT NEUROPATHIC PAIN. DIFFERENT CLASS I HDACIS WERE DELIVERED INTRATHECALLY INTO RAT SPINAL CORD IN MODELS OF TRAUMATIC NERVE INJURY AND ANTIRETROVIRAL DRUG-INDUCED PERIPHERAL NEUROPATHY (STAVUDINE, D4T). MECHANICAL AND THERMAL HYPERSENSITIVITY WAS ATTENUATED BY 40% TO 50% AS A RESULT OF HDACI TREATMENT, BUT ONLY IF STARTED BEFORE ANY INSULT. THE DRUGS GLOBALLY INCREASED HISTONE ACETYLATION IN THE SPINAL CORD, BUT APPEARED TO HAVE NO MEASURABLE EFFECTS IN RELEVANT DORSAL ROOT GANGLIA IN THIS TREATMENT PARADIGM, SUGGESTING THAT ANY POTENTIAL MECHANISM SHOULD BE SOUGHT IN THE CENTRAL NERVOUS SYSTEM. MICROARRAY ANALYSIS OF DORSAL CORD RNA REVEALED THE SIGNATURE OF THE SPECIFIC COMPOUND USED (MS-275) AND SUGGESTED THAT ITS MAIN EFFECT WAS MEDIATED THROUGH HDAC1. TAKEN TOGETHER, THESE DATA SUPPORT A ROLE FOR HISTONE ACETYLATION IN THE EMERGENCE OF NEUROPATHIC PAIN. 2013 8 1167 33 CONTRIBUTION OF DORSAL ROOT GANGLION OCTAMER TRANSCRIPTION FACTOR 1 TO NEUROPATHIC PAIN AFTER PERIPHERAL NERVE INJURY. NEUROPATHIC PAIN GENESIS IS RELATED TO GENE ALTERATIONS IN THE DORSAL ROOT GANGLION (DRG) AFTER PERIPHERAL NERVE INJURY. TRANSCRIPTION FACTORS CONTROL GENE EXPRESSION. IN THIS STUDY, WE INVESTIGATED WHETHER OCTAMER TRANSCRIPTION FACTOR 1 (OCT1), A TRANSCRIPTION FACTOR, CONTRIBUTED TO NEUROPATHIC PAIN CAUSED BY CHRONIC CONSTRICTION INJURY (CCI) OF THE SCIATIC NERVE. CHRONIC CONSTRICTION INJURY PRODUCED A TIME-DEPENDENT INCREASE IN THE LEVEL OF OCT1 PROTEIN IN THE IPSILATERAL L4/5 DRG, BUT NOT IN THE SPINAL CORD. BLOCKING THIS INCREASE THROUGH MICROINJECTION OF OCT1 SIRNA INTO THE IPSILATERAL L4/5 DRG ATTENUATED THE INITIATION AND MAINTENANCE OF CCI-INDUCED MECHANICAL ALLODYNIA, HEAT HYPERALGESIA, AND COLD ALLODYNIA AND IMPROVED MORPHINE ANALGESIA AFTER CCI, WITHOUT AFFECTING BASAL RESPONSES TO ACUTE MECHANICAL, HEAT, AND COLD STIMULI AS WELL AS LOCOMOTOR FUNCTIONS. MIMICKING THIS INCREASE THROUGH MICROINJECTION OF RECOMBINANT ADENO-ASSOCIATED VIRUS 5 HARBORING FULL-LENGTH OCT1 INTO THE UNILATERAL L4/5 DRG LED TO MARKED MECHANICAL ALLODYNIA, HEAT HYPERALGESIA, AND COLD ALLODYNIA IN NAIVE RATS. MECHANISTICALLY, OCT1 PARTICIPATED IN CCI-INDUCED INCREASES IN DNMT3A MRNA AND ITS PROTEIN AND DNMT3A-MEDIATED DECREASES IN OPRM1 AND KCNA2 MRNAS AND THEIR PROTEINS IN THE INJURED DRG. THESE FINDINGS INDICATE THAT OCT1 MAY PARTICIPATE IN NEUROPATHIC PAIN AT LEAST IN PART BY TRANSCRIPTIONALLY ACTIVATING DNMT3A AND SUBSEQUENTLY EPIGENETIC SILENCING OF OPRM1 AND KCAN2 IN THE DRG. OCT1 MAY SERVE AS A POTENTIAL TARGET FOR THERAPEUTIC TREATMENTS AGAINST NEUROPATHIC PAIN. 2019 9 710 34 C-TERMINAL DOMAIN SMALL PHOSPHATASE 1 (CTDSP1) REGULATES GROWTH FACTOR EXPRESSION AND AXONAL REGENERATION IN PERIPHERAL NERVE TISSUE. PERIPHERAL NERVE INJURY (PNI) REPRESENTS A MAJOR CLINICAL AND ECONOMIC BURDEN. DESPITE THE ABILITY OF PERIPHERAL NEURONS TO REGENERATE THEIR AXONS AFTER AN INJURY, PATIENTS ARE OFTEN LEFT WITH MOTOR AND/OR SENSORY DISABILITY AND MAY DEVELOP CHRONIC PAIN. SUCCESSFUL REGENERATION AND TARGET ORGAN REINNERVATION REQUIRE COMPREHENSIVE TRANSCRIPTIONAL CHANGES IN BOTH INJURED NEURONS AND SUPPORT CELLS LOCATED AT THE SITE OF INJURY. THE EXPRESSION OF MOST OF THE GENES REQUIRED FOR AXON GROWTH AND GUIDANCE AND FOR SYNAPSIS FORMATION IS REPRESSED BY A SINGLE MASTER TRANSCRIPTIONAL REGULATOR, THE REPRESSOR ELEMENT 1 SILENCING TRANSCRIPTION FACTOR (REST). SUSTAINED INCREASE OF REST LEVELS AFTER INJURY INHIBITS AXON REGENERATION AND LEADS TO CHRONIC PAIN. AS TARGETING OF TRANSCRIPTION FACTORS IS CHALLENGING, WE TESTED WHETHER MODULATION OF REST ACTIVITY COULD BE ACHIEVED THROUGH KNOCKDOWN OF CARBOXY-TERMINAL DOMAIN SMALL PHOSPHATASE 1 (CTDSP1), THE ENZYME THAT STABILIZES REST BY PREVENTING ITS TARGETING TO THE PROTEASOME. TO TEST WHETHER KNOCKDOWN OF CTDSP1 PROMOTES NEUROTROPHIC FACTOR EXPRESSION IN BOTH SUPPORT CELLS LOCATED AT THE SITE OF INJURY AND IN PERIPHERAL NEURONS, WE TRANSFECTED MESENCHYMAL PROGENITOR CELLS (MPCS), A TYPE OF SUPPORT CELLS THAT ARE PRESENT AT HIGH CONCENTRATIONS AT THE SITE OF INJURY, AND DORSAL ROOT GANGLION (DRG) NEURONS WITH REST OR CTDSP1 SPECIFIC SIRNA. WE QUANTIFIED NEUROTROPHIC FACTOR EXPRESSION BY RT-QPCR AND WESTERN BLOT, AND BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) RELEASE IN THE CELL CULTURE MEDIUM BY ELISA, AND WE MEASURED NEURITE OUTGROWTH OF DRG NEURONS IN CULTURE. OUR RESULTS SHOW THAT CTDSP1 KNOCKDOWN PROMOTES NEUROTROPHIC FACTOR EXPRESSION IN BOTH DRG NEURONS AND THE SUPPORT CELLS MPCS, AND PROMOTES DRG NEURON REGENERATION. THERAPEUTICS TARGETING CTDSP1 ACTIVITY MAY, THEREFORE, REPRESENT A NOVEL EPIGENETIC STRATEGY TO PROMOTE PERIPHERAL NERVE REGENERATION AFTER PNI BY PROMOTING THE REGENERATIVE PROGRAM REPRESSED BY INJURY-INDUCED INCREASED LEVELS OF REST IN BOTH NEURONS AND SUPPORT CELLS. 2021 10 3141 36 GLOBAL GENE EXPRESSION AND CHROMATIN ACCESSIBILITY OF THE PERIPHERAL NERVOUS SYSTEM IN ANIMAL MODELS OF PERSISTENT PAIN. BACKGROUND: EFFORTS TO UNDERSTAND GENETIC VARIABILITY INVOLVED IN AN INDIVIDUAL'S SUSCEPTIBILITY TO CHRONIC PAIN SUPPORT A ROLE FOR UPSTREAM REGULATION BY EPIGENETIC MECHANISMS. METHODS: TO EXAMINE THE TRANSCRIPTOMIC AND EPIGENETIC BASIS OF CHRONIC PAIN THAT RESIDES IN THE PERIPHERAL NERVOUS SYSTEM, WE USED RNA-SEQ AND ATAC-SEQ OF THE RAT DORSAL ROOT GANGLION (DRG) TO IDENTIFY NOVEL MOLECULAR PATHWAYS ASSOCIATED WITH PAIN HYPERSENSITIVITY IN TWO WELL-STUDIED PERSISTENT PAIN MODELS INDUCED BY CHRONIC CONSTRICTION INJURY (CCI) OF THE SCIATIC NERVE AND INTRA-PLANTAR INJECTION OF COMPLETE FREUND'S ADJUVANT (CFA) IN RATS. RESULTS: OUR RNA-SEQ STUDIES IDENTIFY A VARIETY OF BIOLOGICAL PROCESS RELATED TO SYNAPSE ORGANIZATION, MEMBRANE POTENTIAL, TRANSMEMBRANE TRANSPORT, AND ION BINDING. INTERESTINGLY, GENES THAT ENCODE TRANSCRIPTIONAL REGULATORS WERE DISPROPORTIONATELY DOWNREGULATED IN BOTH MODELS. OUR ATAC-SEQ DATA PROVIDE A COMPREHENSIVE MAP OF CHROMATIN ACCESSIBILITY CHANGES IN THE DRG. A TOTAL OF 1123 REGIONS SHOWED CHANGES IN CHROMATIN ACCESSIBILITY IN ONE OR BOTH MODELS WHEN COMPARED TO THE NAIVE AND 31 SHARED DIFFERENTIALLY ACCESSIBLE REGIONS (DAR)S. FUNCTIONAL ANNOTATION OF THE DARS IDENTIFIED DISPARATE MOLECULAR FUNCTIONS ENRICHED FOR EACH PAIN MODEL WHICH SUGGESTS THAT CHROMATIN STRUCTURE MAY BE ALTERED DIFFERENTLY FOLLOWING SCIATIC NERVE INJURY AND HIND PAW INFLAMMATION. MOTIF ANALYSIS IDENTIFIED 17 DNA SEQUENCES KNOWN TO BIND TRANSCRIPTION FACTORS IN THE CCI DARS AND 33 IN THE CFA DARS. TWO MOTIFS WERE SIGNIFICANTLY ENRICHED IN BOTH MODELS. CONCLUSIONS: OUR IMPROVED UNDERSTANDING OF THE CHANGES IN CHROMATIN ACCESSIBILITY THAT OCCUR IN CHRONIC PAIN STATES MAY IDENTIFY REGULATORY GENOMIC ELEMENTS THAT PLAY ESSENTIAL ROLES IN MODULATING GENE EXPRESSION IN THE DRG. 2021 11 804 36 CENTRAL ENDOTHELIN-1 CONFERS ANALGESIA BY TRIGGERING SPINAL NEURONAL HISTONE DEACETYLASE 5 (HDAC5) NUCLEAR EXCLUSION IN PERIPHERAL NEUROPATHIC PAIN IN MICE. THE RATIONALE OF SPINAL ADMINISTRATION OF ENDOTHELIN-1(ET-1) MEDIATED ANTI-NOCICEPTIVE EFFECT HAS NOT BEEN ELUCIDATED. ET-1 IS REPORTED TO PROMOTE NUCLEAR EFFLUXION OF HISTONE DEACETYLASE 5 (HDAC5) IN MYOCYTES, AND SPINAL HDAC5 IS IMPLICATED IN MODULATION OF PAIN PROCESSING. IN THIS STUDY, WE AIMED TO INVESTIGATE WHETHER CENTRAL ET-1 PLAYS AN ANTI-NOCICEPTIVE ROLE BY FACILITATING SPINAL HDAC5 NUCLEAR SHUTTLING UNDER NEUROPATHIC PAIN. HERE, WE DEMONSTRATE THAT UPREGULATING SPINAL ET-1 ATTENUATED THE NOCICEPTION INDUCED BY PARTIAL SCIATIC NERVE LIGATION SURGERY AND THIS ANALGESIC EFFECT MEDIATED BY ET-1 WAS ATTENUATED BY INTRATHECAL INJECTION OF ENDOTHELIN A RECEPTOR SELECTIVE INHIBITOR (BQ123) OR BY BLOCKING THE EXPORTATION OF NUCLEAR HDAC5 BY ADENO-ASSOCIATED VIRUSES TARGETING NEURONAL HDAC5 (AVV-HDAC5 S259/498A MUTANT). NOTABLY, ET-1 ADMINISTRATION INCREASED SPINAL GLUTAMATE ACID DECARBOXYLASES (GAD65/67) EXPRESSION VIA INITIATING HDAC5 NUCLEAR EXPORTATION AND INCREASED THE ACETYLATION OF HISTONE 3 AT LYSINE 9 (ACETYL-H3K9) IN THE PROMOTOR REGIONS OF SPINAL GAD1 AND GAD2 GENES. THIS WAS REVERSED BY BLOCKING ENDOTHELIN A RECEPTOR FUNCTION OR BY INHIBITING THE SPINAL NEURONAL NUCLEAR EXPORTATION OF HDAC5. THEREFORE, INDUCING SPINAL GABAERGIC NEURONAL HDAC5 NUCLEAR EXPORTATION MAY BE A NOVEL THERAPEUTIC APPROACH FOR MANAGING NEUROPATHIC PAIN. PERSPECTIVE: NEUROPATHIC PAIN IS INTRACTABLE IN A CLINICAL SETTING, AND EPIGENETIC REGULATION IS CONSIDERED TO CONTRIBUTE TO THIS PROCESSING. CHARACTERIZING THE ANTI-NOCICEPTIVE EFFECT OF ET-1 AND INVESTIGATING THE ASSOCIATED EPIGENETIC MECHANISMS IN ANIMAL MODELS MAY LEAD TO THE DEVELOPMENT OF NEW THERAPEUTIC STRATEGIES AND TARGETS FOR TREATING NEUROPATHIC PAIN. 2021 12 5347 23 RARBETA AGONIST DRUG (C286) DEMONSTRATES EFFICACY IN A PRE-CLINICAL NEUROPATHIC PAIN MODEL RESTORING MULTIPLE PATHWAYS VIA DNA REPAIR MECHANISMS. NEUROPATHIC PAIN (NP) IS ASSOCIATED WITH PROFOUND GENE EXPRESSION ALTERATIONS WITHIN THE NOCICEPTIVE SYSTEM. DNA MECHANISMS, SUCH AS EPIGENETIC REMODELING AND REPAIR PATHWAYS HAVE BEEN IMPLICATED IN NP. HERE WE HAVE USED A RAT MODEL OF PERIPHERAL NERVE INJURY TO STUDY THE EFFECT OF A RECENTLY DEVELOPED RARBETA AGONIST, C286, CURRENTLY UNDER CLINICAL RESEARCH, IN NP. A 4-WEEK TREATMENT INITIATED 2 DAYS AFTER THE INJURY NORMALIZED PAIN SENSATION. GENOME-WIDE AND PATHWAY ENRICHMENT ANALYSIS SHOWED THAT MULTIPLE MECHANISMS PERSISTENTLY ALTERED IN THE SPINAL CORD WERE RESTORED TO PREINJURY LEVELS BY THE AGONIST. CONCOMITANT UPREGULATION OF DNA REPAIR PROTEINS, ATM AND BRCA1, THE LATTER BEING REQUIRED FOR C286-MEDIATED PAIN MODULATION, SUGGESTS THAT EARLY DNA REPAIR MAY BE IMPORTANT TO PREVENT PHENOTYPIC EPIGENETIC IMPRINTS IN NP. THUS, C286 IS A PROMISING DRUG CANDIDATE FOR NEUROPATHIC PAIN AND DNA REPAIR MECHANISMS MAY BE USEFUL THERAPEUTIC TARGETS TO EXPLORE. 2019 13 5599 33 ROLES OF THE NEURON-RESTRICTIVE SILENCER FACTOR IN THE PATHOPHYSIOLOGICAL PROCESS OF THE CENTRAL NERVOUS SYSTEM. THE NEURON-RESTRICTIVE SILENCER FACTOR (NRSF), ALSO KNOWN AS REPRESSOR ELEMENT 1 (RE-1) SILENCING TRANSCRIPTION FACTOR (REST) OR X2 BOX REPRESSOR (XBR), IS A ZINC FINGER TRANSCRIPTION FACTOR THAT IS WIDELY EXPRESSED IN NEURONAL AND NON-NEURONAL CELLS. IT IS A MASTER REGULATOR OF THE NERVOUS SYSTEM, AND THE FUNCTION OF NRSF IS THE BASIS OF NEURONAL DIFFERENTIATION, DIVERSITY, PLASTICITY, AND SURVIVAL. NRSF CAN BIND TO THE NEURON-RESTRICTIVE SILENCER ELEMENT (NRSE), RECRUIT SOME CO-REPRESSORS, AND THEN INHIBIT TRANSCRIPTION OF NRSE DOWNSTREAM GENES THROUGH EPIGENETIC MECHANISMS. IN NEUROGENESIS, NRSF FUNCTIONS NOT ONLY AS A TRANSCRIPTIONAL SILENCER THAT CAN MEDIATE THE TRANSCRIPTIONAL INHIBITION OF NEURON-SPECIFIC GENES IN NON-NEURONAL CELLS AND THUS GIVE NEURON CELLS SPECIFICITY, BUT ALSO AS A TRANSCRIPTIONAL ACTIVATOR TO INDUCE NEURONAL DIFFERENTIATION. MANY STUDIES HAVE CONFIRMED THE ASSOCIATION BETWEEN NRSF AND BRAIN DISORDERS, SUCH AS BRAIN INJURY AND NEURODEGENERATIVE DISEASES. OVEREXPRESSION, UNDEREXPRESSION, OR MUTATION MAY LEAD TO NEUROLOGICAL DISORDERS. IN TUMORIGENESIS, NRSF FUNCTIONS AS AN ONCOGENE IN NEURONAL TUMORS, SUCH AS NEUROBLASTOMAS, MEDULLOBLASTOMAS, AND PHEOCHROMOCYTOMAS, STIMULATING THEIR PROLIFERATION, WHICH RESULTS IN POOR PROGNOSIS. ADDITIONALLY, NRSF-MEDIATED SELECTIVE TARGETS GENE REPRESSION PLAYS AN IMPORTANT ROLE IN THE DEVELOPMENT AND MAINTENANCE OF NEUROPATHIC PAIN CAUSED BY NERVE INJURY, CANCER, AND DIABETES. AT PRESENT, SEVERAL COMPOUNDS THAT TARGET NRSF OR ITS CO-REPRESSORS, SUCH AS REST-VP16 AND X5050, HAVE BEEN SHOWN TO BE CLINICALLY EFFECTIVE AGAINST MANY BRAIN DISEASES, SUCH AS SEIZURES, IMPLYING THAT NRSF AND ITS CO-REPRESSORS MAY BE POTENTIAL AND PROMISING THERAPEUTIC TARGETS FOR NEURAL DISORDERS. IN THE PRESENT REVIEW, WE INTRODUCED THE BIOLOGICAL CHARACTERISTICS OF NRSF; REVIEWED THE PROGRESS TO DATE IN UNDERSTANDING THE ROLES OF NRSF IN THE PATHOPHYSIOLOGICAL PROCESSES OF THE NERVOUS SYSTEM, SUCH AS NEUROGENESIS, BRAIN DISORDERS, NEURAL TUMORIGENESIS, AND NEUROPATHIC PAIN; AND SUGGESTED NEW THERAPEUTIC APPROACHES TO SUCH BRAIN DISEASES. 2022 14 2112 36 EPIGENETIC GENE SILENCING UNDERLIES C-FIBER DYSFUNCTIONS IN NEUROPATHIC PAIN. PERIPHERAL NERVE INJURY CAUSES NEUROPATHIC PAIN, WHICH IS CHARACTERIZED BY THE PARADOXICAL SENSATIONS OF POSITIVE AND NEGATIVE SYMPTOMS. CLINICALLY, NEGATIVE SIGNS ARE FREQUENTLY OBSERVED; HOWEVER, THEIR UNDERLYING MOLECULAR MECHANISMS ARE LARGELY UNKNOWN. DYSFUNCTION OF C-FIBERS IS ASSUMED TO UNDERLIE NEGATIVE SYMPTOMS AND IS ACCOMPANIED BY LONG-LASTING DOWNREGULATION OF NA(V)1.8 SODIUM CHANNEL AND MU-OPIOID RECEPTOR (MOP) IN THE DORSAL ROOT GANGLION (DRG). IN THE PRESENT STUDY, WE FOUND THAT NERVE INJURY UPREGULATES NEURON-RESTRICTIVE SILENCER FACTOR (NRSF) EXPRESSION IN THE DRG NEURONS MEDIATED THROUGH EPIGENETIC MECHANISMS. IN ADDITION, CHROMATIN IMMUNOPRECIPITATION ANALYSIS REVEALED THAT NERVE INJURY PROMOTES NRSF BINDING TO THE NEURON-RESTRICTIVE SILENCER ELEMENT WITHIN MOP AND NA(V)1.8 GENES, THEREBY CAUSING EPIGENETIC SILENCING. FURTHERMORE, NRSF KNOCKDOWN SIGNIFICANTLY BLOCKED NERVE INJURY-INDUCED DOWNREGULATIONS OF MOP AND NA(V)1.8 GENE EXPRESSIONS, C-FIBER HYPOESTHESIA, AND THE LOSSES OF PERIPHERAL MORPHINE ANALGESIA AND NA(V)1.8-SELECTIVE BLOCKER-INDUCED HYPOESTHESIA. TOGETHER, THESE DATA SUGGEST THAT NRSF CAUSES PATHOLOGICAL AND PHARMACOLOGICAL DYSFUNCTION OF C-FIBERS, WHICH UNDERLIES THE NEGATIVE SYMPTOMS IN NEUROPATHIC PAIN. 2010 15 6148 32 THE EXPRESSION OF TRANSCRIPTION FACTORS MECP2 AND CREB IS MODULATED IN INFLAMMATORY PELVIC PAIN. EARLY ACTIVATION OF TRANSCRIPTION FACTORS IS ONE OF THE EPIGENETIC MECHANISMS CONTRIBUTING TO THE INDUCTION AND MAINTENANCE OF CHRONIC PAIN STATES. PREVIOUS STUDIES IDENTIFIED THE CHANGES IN A NUMBER OF NOCICEPTION-RELATED GENES, SUCH AS CALCITONIN GENE-RELATED PEPTIDE (CGRP), SUBSTANCE P (SP), AND BRAIN-DERIVED NEUROTROPIC FACTOR (BDNF) IN THE PELVIC ORGANS AFTER TRANSIENT COLONIC INFLAMMATION. THE GENE AND PROTEIN EXPRESSION OF THESE NEUROPEPTIDES COULD BE MODULATED BY TRANSCRIPTION FACTORS METHYL-CPG-BINDING PROTEIN 2 (MECP2) AND CAMP RESPONSE ELEMENT-BINDING PROTEIN (CREB). IN THIS STUDY, WE AIMED TO EVALUATE TIME-DEPENDENT CHANGES IN THE EXPRESSION LEVELS OF MECP2 AND CREB IN THE LUMBOSACRAL (LS) SPINAL CORD AND SENSORY GANGLIA AFTER INFLAMMATION-INDUCED PELVIC PAIN IN RAT. ADULT SPRAGUE-DAWLEY RATS WERE TREATED WITH 2,4,6-TRINITROBENZENESULFONIC ACID (TNBS) TO INDUCE TRANSIENT COLONIC INFLAMMATION. LS (L6-S2) SPINAL CORD SEGMENTS AND RESPECTIVE DORSAL ROOT GANGLIAS (DRGS) WERE ISOLATED FROM CONTROL AND EXPERIMENTAL ANIMALS AT 1, 2, 6, 24 H AND 3 DAYS POST-TNBS TREATMENT. IMMUNOHISTOCHEMICAL (IHC) LABELING AND WESTERN BLOTTING EXPERIMENTS WERE PERFORMED TO ASSESS THE EXPRESSION OF MECP2, CREB AND THEIR PHOSPHORYLATED FORMS. TOTAL MECP2 EXPRESSION, BUT NOT PHOSPHORYLATED P-MECP2 (PS421MECP2) EXPRESSION WAS DETECTED IN THE CELLS OF THE SPINAL DORSAL HORN UNDER CONTROL CONDITIONS. COLONIC INFLAMMATION TRIGGERED A SIGNIFICANT DECREASE IN THE NUMBER OF MECP2-EXPRESSING NEURONS IN PARALLEL WITH ELEVATED NUMBERS OF PS421MECP2-EXPRESSING CELLS AT 2 H AND 6 H POST-TNBS. THE MAJORITY OF MECP2-POSITIVE CELLS (80 +/- 6%) CO-EXPRESSED CREB. TNBS TREATMENT CAUSED A TRANSIENT UP-REGULATION OF CREB-EXPRESSING CELLS AT 1 H POST-TNBS ONLY. THE NUMBER OF CELLS EXPRESSING PHOSPHORYLATED CREB (PS133CREB) DID NOT CHANGE AT 1 H AND 2 H POST-TNBS, BUT WAS DOWN-REGULATED BY THREE FOLDS AT 6 H POST-TNBS. ANALYSIS OF DRG SECTIONS REVEALED THAT THE NUMBER OF MECP2-POSITIVE NEURONS WAS UP-REGULATED BY TNBS TREATMENT, REACHING THREE-FOLD INCREASE AT 2 H POST-TNBS, AND EIGHT-FOLD INCREASE AT 6 H POST-TNBS (P