1 3868 158 JMJD6 EXERTS FUNCTION IN NEUROPATHIC PAIN BY REGULATING NF?KAPPAB FOLLOWING PERIPHERAL NERVE INJURY IN RATS. TREATMENT OF NEUROPATHIC PAIN (NPP) CONTINUES TO BE A MAJOR CHALLENGE, AND THE UNDERLYING MECHANISMS REMAIN TO BE ELUCIDATED. PREVIOUS STUDIES HAVE DEMONSTRATED THAT HISTONE METHYLATION IS IMPORTANT IN SYNAPTIC PLASTICITY OF THE NERVOUS SYSTEM AND MAY AFFECT NUCLEAR FACTOR?KAPPAB (NF?KAPPAB) SIGNALING THROUGH EPIGENETIC MECHANISMS. THE PRESENT STUDY AIMED TO INVESTIGATE THE ROLE OF JUMONJI C DOMAIN 6 (JMJD6), A HISTONE DEMETHYLASE, IN A CHRONIC CONSTRICTION INJURY (CCI) MODEL OF NPP. ON THE THIRD DAY POST?CCI SURGERY, A JMJD6 OVEREXPRESSING LENTIVIRAL VECTOR (LV?JMJD6) WAS INTRATHECALLY INJECTED IN THE RATS. MECHANICAL WITHDRAWAL THRESHOLD AND THERMAL WITHDRAWAL LATENCY WERE ASSESSED PRIOR SURGERY AND ON DAYS 3, 7, 10 AND 14 POST?CCI. THE RESULTS SHOWED THAT INTRATHECAL INJECTION WITH THE LV?JMJD6 ATTENUATED CCI?INDUCED PAIN FACILITATION. THE EXPRESSION OF JMJD6 WAS LOWER FOLLOWING CCI SURGERY, AND ITS EXPRESSION WAS SIGNIFICANTLY INCREASED FOLLOWING INTRATHECAL INJECTION WITH LV?JMJD6, COMPARED WITH LEVELS IN NORMAL SALINE (NS)? AND NEGATIVE CONTROL LENTIVIRAL VECTOR (NC)?TREATED RATS. THE EXPRESSION OF SPINAL NF?KAPPAB PHOSPHORYLATED (P?)P65 SUBUNIT AND ITS DOWNSTREAM PAIN?ASSOCIATED EFFECTORS, INCLUDING INTERLEUKIN 1BETA (IL?1BETA), TUMOR NECROSIS FACTOR?ALPHA (TNF?ALPHA) AND VASCULAR ENDOTHELIAL GROWTH FACTOR (VEGF), WERE INCREASED FOLLOWING CCI SURGERY. INTRATHECAL INJECTION WITH LV?JMJD6 SUPPRESSED ACTIVATION OF THE P?P65 SUBUNIT IN CCI RATS. IN ADDITION, EXPRESSION LEVELS OF ITS DOWNSTREAM EFFECTORS IL?1BETA, TNF?ALPHA AND VEGF WERE ATTENUATED BY INTRATHECAL TREATMENT WITH LV?JMJD6, COMPARED WITH THOSE IN THE NS? AND NC?TREATED CCI RATS. FURTHERMORE, THE JMJD6? AND P65?IMMUNOREACTIVE CELLS OVERLAPPED IN THE SPINAL DORSAL HORN, HOWEVER, CO?IMMUNOPRECIPITATION SHOWED THAT JMJD6 AND THE NF?KAPPAB P65 SUBUNIT DID NOT DIRECTLY INTERACT, INDICATING OTHER FUNCTIONAL CONNECTIONS MAY EXIST BETWEEN THESE FACTORS FOLLOWING CCI SURGERY. COLLECTIVELY, THESE FINDINGS INDICATED AN IMPORTANT MECHANISM UNDERLYING THE PATHOGENESIS OF NPP. JMJD6 MAY EXERT ITS THERAPEUTIC FUNCTION IN NPP BY REGULATING NF?KAPPAB FOLLOWING CCI. 2018 2 3810 47 INTRATHECAL 5-AZACYTIDINE INHIBITS GLOBAL DNA METHYLATION AND METHYL- CPG-BINDING PROTEIN 2 EXPRESSION AND ALLEVIATES NEUROPATHIC PAIN IN RATS FOLLOWING CHRONIC CONSTRICTION INJURY. THE PATHOGENESIS OF NEUROPATHIC PAIN REMAINS LARGELY UNKNOWN. EPIGENETIC MECHANISMS MAY PLAY A MAJOR ROLE IN REGULATING EXPRESSION OF PRO- OR ANTINOCICEPTIVE GENES. DNA METHYLATION IS A MAJOR EPIGENETIC MECHANISM IN VERTEBRATES, AND METHYL- CPG-BINDING PROTEIN 2 (MECP2) IS DIRECTLY INVOLVED IN METHYLATION-MEDIATED GENE SILENCING. TO DETERMINE HOW CHANGES IN GLOBAL DNA METHYLATION AND MECP2 EXPRESSION OCCUR FOLLOWING CHRONIC CONSTRICTION INJURY (CCI) AND HOW REPRESSION OF DNA METHYLATION AFFECTS THESE CHANGES AND ATTENUATES NEUROPATHIC PAIN, WE USED INTRATHECAL 5-AZACYTIDINE, A DNA METHYLTRANSFERASE INHIBITOR, IN CCI RATS. RATS RECEIVED 0.9% SALINE OR 5-AZACYTIDINE (10MUMOL.D(-1)) VIA SPINAL INJECTION ONCE DAILY FROM DAY 3 TO DAY 14 AFTER CCI SURGERY. GLOBAL DNA METHYLATION AND MECP2 EXPRESSION INCREASED IN THE SPINAL CORD IN CCI RATS ON DAY 14 AFTER CCI SURGERY. MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA INDUCED BY CCI WERE ATTENUATED BY INTRATHECAL 5-AZACYTIDINE FROM DAY 5 TO DAY 14 AFTER CCI SURGERY. THE INCREASES IN GLOBAL DNA METHYLATION AND MECP2 EXPRESSION IN THE SPINAL CORD IN CCI RATS WERE ALSO SIGNIFICANTLY INHIBITED BY INTRATHECAL 5-AZACYTIDINE. THESE RESULTS DEMONSTRATE THAT INCREASED GLOBAL DNA METHYLATION AND MECP2 EXPRESSION IN THE SPINAL CORD AFTER NERVE DAMAGE MAY PLAY AN IMPORTANT ROLE IN NEUROPATHIC PAIN. 5-AZACYTIDINE SHOWS POTENTIAL FOR TREATING NEUROPATHIC PAIN. 2011 3 3832 44 INVOLVEMENT OF SPINAL SIRT1 IN DEVELOPMENT OF CHRONIC CONSTRICTION INJURY INDUCED NEUROPATHIC PAIN IN RATS. IT IS KNOWN THAT THE EPIGENETIC PROCESS OF HISTONE ACETYLATION IS INVOLVED IN THE NEUROPATHIC PAIN. THE AIM OF THIS STUDY WAS TO DETERMINE WHETHER SIRTUIN TYPE 1 (SIRT1), AN NAD(+) DEPENDENT DEACETYLASE, AFFECTED ALLODYNIA AND HYPERALGESIA IN NEUROPATHIC PAIN. THE NEUROPATHIC PAIN MODEL WAS ESTABLISHED BY LIGATURE OF THE RIGHT SCIATIC NERVE TO INDUCE CHRONIC CONSTRICTION INJURY (CCI) IN RATS. HISTONE ACETYLTRANSFERASE (HAT) ACTIVITY WAS INCREASED AND, AND HISTONE DEACETYLASE (HDAC) ACTIVITY WAS DECLINED IN TISSUE OF THE SPINAL DORSA HORN IN CCI RATES BY MEANS OF ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA). THE PERSISTENT HYPERALGESIA AND ALLODYNIA CAUSED BY CCI WERE ASSOCIATED WITH DOWNREGULATION OF SIRT1 AND UPREGULATION OF ACETYLATED-H3 (AC-H3) IN TISSUE OF THE SPINAL CORD BY WESTERN BLOT ASSAY, WHICH WAS REVERSED AFTER INTRATHECAL INJECTION OF SIRT1 AGONIST SRT1720. SRT1720 TREATMENT ACHIEVED ANALGESIC THROUGH INHIBITING THE ACETYLATION OF NUCLEAR FACTOR KAPPA B (NF-KAPPAB) AND BLOCKING THE RELEASES OF THE INFLAMMATORY FACTORS INCLUDING TUMOR NECROSIS FACTOR-ALPHA (TNF-ALPHA) AND INTERLEUKIN (IL)-6 BY MEANS OF WESTERN BLOT AND REAL-TIME QUANTITATIVE PCR (RT-PCR), RESPECTIVELY. TAKEN TOGETHER, THESE DATA SUGGEST THAT SIRT1 IN THE SPINAL CORD PLAYS AN IMPORTANT ROLE IN THE NEUROPATHIC PAIN IN THE RAT MODEL. 2018 4 2253 47 EPIGENETIC MODULATION OF WNT SIGNALING CONTRIBUTES TO NEUROPATHIC PAIN IN RATS. PREVIOUS STUDIES HAVE DEMONSTRATED THAT THE WNT/BETA?CATENIN SIGNALING PATHWAY IS CRITICAL TO THE INDUCTION AND MAINTENANCE OF CHRONIC NEUROPATHIC PAIN CAUSED BY PERIPHERAL INFLAMMATION AND NERVE DAMAGE. EMERGING EVIDENCE FROM RECENT STUDIES SUGGESTS THAT EPIGENETIC MECHANISMS MAY ALSO BE CRITICAL TO THE PATHOGENESIS OF CHRONIC PAIN. THE PRESENT STUDY AIMED TO ELUCIDATE THE EPIGENETIC MECHANISMS UNDERLYING ALTERED WNT SIGNALING AND THEIR INVOLVEMENT IN CCI?INDUCED NEUROPATHIC PAIN IN RAT SCIATIC NERVES. THE RESULTS OF THE PRESENT STUDY DEMONSTRATED A SIGNIFICANT INCREASE IN THE EXPRESSION LEVELS OF WNT3A IN THE DORSAL HORN OF THE RATS WITH CCI. IN ADDITION, A SIGNIFICANT INCREASE IN HISTONE H3 ACETYLATION, AND A SIGNIFICANT DECREASE IN CYTOSINE METHYLATION IN THE PROMOTER REGION OF WNT3A WAS OBSERVED IN THE DORSAL HORN OF THE RATS WITH CCI. INTRATHECAL APPLICATION OF XAV939, WHICH ACTS AS AN INHIBITOR OF WNT SIGNALING, SIGNIFICANTLY DECREASED THE EXPRESSION LEVELS OF ACTIVE BETA?CATENIN, AND ATTENUATED THE RAT BEHAVIORAL RESPONSES TO THERMAL AND MECHANICAL PAIN STIMULI. THESE RESULTS SUGGEST THAT THE EPIGENETIC UPREGULATION OF WNT3A IN THE DORSAL HORN CONTRIBUTES TO THE MAINTENANCE OF PAIN?INDUCED BEHAVIOR IN RATS WITH CCI. 2015 5 5781 53 SPINAL SIRT1 ACTIVATION ATTENUATES NEUROPATHIC PAIN IN MICE. ABNORMAL HISTONE ACETYLATION OCCURS DURING NEUROPATHIC PAIN THROUGH AN EPIGENETIC MECHANISM. SILENT INFORMATION REGULATOR 1 (SIR2 OR SIRT1), A NAD-DEPENDENT DEACETYLASE, PLAYS COMPLEX SYSTEMIC ROLES IN A VARIETY OF PROCESSES THROUGH DEACETYLATING ACETYLATED HISTONE AND OTHER SPECIFIC SUBSTRATES. BUT THE ROLE OF SIRT1 IN NEUROPATHIC PAIN IS NOT WELL ESTABLISHED YET. THE PRESENT STUDY WAS INTENDED TO DETECT SIRT1 CONTENT AND ACTIVITY, NICOTINAMIDE (NAM) AND NICOTINAMIDE ADENINE DINUCLEOTIDE (NAD) IN THE SPINAL CORD USING IMMUNOBLOTTING OR MASS SPECTROSCOPY OVER TIME IN MICE FOLLOWING CHRONIC CONSTRICTION INJURY (CCI) OR SHAM SURGERY. IN ADDITION, THE EFFECT OF INTRATHECAL INJECTION OF NAD OR RESVERATROL ON THERMAL HYPERALGESIA AND MECHANICAL ALLODYNIA WAS EVALUATED IN CCI MICE. FINALLY, WE INVESTIGATED WHETHER SIRT1 INHIBITOR EX-527 COULD REVERSE THE ANTI-NOCICEPTIVE EFFECT OF NAD OR RESVERATROL. IT WAS FOUND THAT SPINAL SIRT1 EXPRESSION, DEACETYLASE ACTIVITY AND NAD/NAM DECREASED SIGNIFICANTLY 1, 3, 7, 14 AND 21 DAYS AFTER CCI SURGERY AS COMPARED WITH SHAM GROUP. IN ADDITION, DAILY INTRATHECAL INJECTION OF 5 MICROL 800 MM NAD 1 H BEFORE AND 1 DAY AFTER CCI SURGERY OR SINGLE INTRATHECAL INJECTION OF 5 MICROL 90 MM RESVERATROL 1 H BEFORE CCI SURGERY PRODUCED A TRANSIENT INHIBITORY EFFECT ON THERMAL HYPERALGESIA AND MECHANICAL ALLODYNIA IN CCI MICE. FINALLY, AN INTRATHECAL INJECTION OF 5 MICROL 1.2 MM EX-527 1 H BEFORE NAD OR RESVERATROL ADMINISTRATION REVERSED THE ANTI-NOCICEPTIVE EFFECT OF NAD OR RESVERATROL. THESE DATA INDICATE THAT THE REDUCTION IN SIRT1 DEACETYLASE ACTIVITY MAY BE A FACTOR CONTRIBUTING TO THE DEVELOPMENT OF NEUROPATHIC PAIN IN CCI MICE. OUR FINDINGS SUGGEST THAT THE ENHANCEMENT OF SPINAL NAD/NAM AND/OR SIRT1 ACTIVITY MAY BE A POTENTIALLY PROMISING STRATEGY FOR THE PREVENTION OR TREATMENT OF NEUROPATHIC PAIN. 2014 6 4906 55 P300 EXERTS AN EPIGENETIC ROLE IN CHRONIC NEUROPATHIC PAIN THROUGH ITS ACETYLTRANSFERASE ACTIVITY IN RATS FOLLOWING CHRONIC CONSTRICTION INJURY (CCI). BACKGROUND: NEUROPATHIC PAIN IS DETRIMENTAL TO HUMAN HEALTH; HOWEVER, ITS PATHOGENESIS STILL REMAINS LARGELY UNKNOWN. OVEREXPRESSION OF PAIN-ASSOCIATED GENES AND INCREASED NOCICEPTIVE SOMATO-SENSITIVITY ARE WELL OBSERVED IN NEUROPATHIC PAIN. THE IMPORTANCE OF EPIGENETIC MECHANISMS IN REGULATING THE EXPRESSION OF PRO- OR ANTI-NOCICEPTIVE GENES HAS BEEN REVEALED BY STUDIES RECENTLY, AND WE HYPOTHESIZE THAT THE TRANSCRIPTIONAL COACTIVATOR AND THE HISTONE ACETYLTRANSFERASE E1A BINDING PROTEIN P300 (P300), AS A PART OF THE EPIGENETIC MECHANISMS OF GENE REGULATION, MAY BE INVOLVED IN THE PATHOGENESIS OF NEUROPATHIC PAIN INDUCED BY CHRONIC CONSTRICTION INJURY (CCI). TO TEST THIS HYPOTHESIS, TWO DIFFERENT APPROACHES WERE USED IN THIS STUDY: (I) DOWN-REGULATING P300 WITH SPECIFIC SMALL HAIRPIN RNA (SHRNA) AND (II) CHEMICAL INHIBITION OF P300 ACETYLTRANSFERASE ACTIVITY BY A SMALL MOLECULE INHIBITOR, C646. RESULTS: USING THE CCI RAT MODEL, WE FOUND THAT THE P300 EXPRESSION WAS INCREASED IN THE LUMBAR SPINAL CORD ON DAY 14 AFTER CCI. THE TREATMENT WITH INTRATHECAL P300 SHRNA REVERSED CCI-INDUCED MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA, AND SUPPRESSED THE EXPRESSION OF CYCLOOXYGENASE-2 (COX-2), A NEUROPATHIC PAIN-ASSOCIATED FACTOR. FURTHERMORE, C646, AN INHIBITOR OF P300 ACETYLTRANSFERASE, ALSO ATTENUATED MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA, ACCOMPANIED BY A SUPPRESSED COX-2 EXPRESSION, IN THE SPINAL CORD. CONCLUSIONS: THE RESULTS SUGGEST THAT, THROUGH ITS ACETYLTRANSFERASE ACTIVITY IN THE SPINAL CORD AFTER CCI, P300 EPIGENETICALLY PLAYS AN IMPORTANT ROLE IN NEUROPATHIC PAIN. INHIBITING P300, USING INTERFERING RNA OR C646, MAY BE A PROMISING APPROACH TO THE DEVELOPMENT OF NEW NEUROPATHIC PAIN THERAPIES. 2012 7 2785 50 EZH2 REGULATES SPINAL NEUROINFLAMMATION IN RATS WITH NEUROPATHIC PAIN. ALTERATION IN GENE EXPRESSION ALONG THE PAIN SIGNALING PATHWAY IS A KEY MECHANISM CONTRIBUTING TO THE GENESIS OF NEUROPATHIC PAIN. ACCUMULATING STUDIES HAVE SHOWN THAT EPIGENETIC REGULATION PLAYS A CRUCIAL ROLE IN NOCICEPTIVE PROCESS IN THE SPINAL DORSAL HORN. IN THIS PRESENT STUDY, WE INVESTIGATED THE ROLE OF ENHANCER OF ZESTE HOMOLOG-2 (EZH2), A SUBUNIT OF THE POLYCOMB REPRESSIVE COMPLEX 2, IN THE SPINAL DORSAL HORN IN THE GENESIS OF NEUROPATHIC PAIN IN RATS INDUCED BY PARTIAL SCIATIC NERVE LIGATION. EZH2 IS A HISTONE METHYLTRANSFERASE, WHICH CATALYZES THE METHYLATION OF HISTONE H3 ON K27 (H3K27), RESULTING IN GENE SILENCING. WE FOUND THAT LEVELS OF EZH2 AND TRI-METHYLATED H3K27 (H3K27TM) IN THE SPINAL DORSAL HORN WERE INCREASED IN RATS WITH NEUROPATHIC PAIN ON DAY 3 AND DAY 10 POST NERVE INJURIES. EZH2 WAS PREDOMINANTLY EXPRESSED IN NEURONS IN THE SPINAL DORSAL HORN UNDER NORMAL CONDITIONS. THE NUMBER OF NEURONS WITH EZH2 EXPRESSION WAS INCREASED AFTER NERVE INJURY. MORE STRIKINGLY, NERVE INJURY DRASTICALLY INCREASED THE NUMBER OF MICROGLIA WITH EZH2 EXPRESSION BY MORE THAN SEVENFOLD. INTRATHECAL INJECTION OF THE EZH2 INHIBITOR ATTENUATED THE DEVELOPMENT AND MAINTENANCE OF MECHANICAL AND THERMAL HYPERALGESIA IN RATS WITH NERVE INJURY. SUCH ANALGESIC EFFECTS WERE CONCURRENTLY ASSOCIATED WITH THE REDUCED LEVELS OF EZH2, H3K27TM, IBA1, GFAP, TNF-ALPHA, IL-1BETA, AND MCP-1 IN THE SPINAL DORSAL HORN IN RATS WITH NERVE INJURY. OUR RESULTS HIGHLY SUGGEST THAT TARGETING THE EZH2 SIGNALING PATHWAY COULD BE AN EFFECTIVE APPROACH FOR THE MANAGEMENT OF NEUROPATHIC PAIN. 2017 8 4579 39 N(6)-METHYLADENOSINE METHYLASE METTL3 CONTRIBUTES TO NEUROPATHIC PAIN BY EPIGENETIC SILENCING OF MU OPIOID RECEPTOR. WE AIMED AT EXPLORING THE ROLE AND MECHANISM OF METTL3-MEDIATED M(6)A MODIFICATION IN NEUROPATHIC PAIN. MALE SPRAGUE-DAWLEY RATS WERE RANDOMLY DIVIDED INTO FOUR GROUPS: SHAM OPERATION GROUP (SHAM GROUP), CHRONIC CONSTRICTION INJURY (CCI) OF THE SCIATIC NERVE MODEL GROUP (NPP GROUP), INTRATHECAL INJECTION OF VIRUS DOWN-REGULATED METTL3 + CCI MODEL GROUP (M3 + NPP GROUP) AND INTRATHECAL INJECTION OF NEGATIVE CONTROL VIRUS + CCI MODEL GROUP (SCR + NPP GROUP). THE M3 + NPP GROUP AND THE SCR + NPP GROUP WERE INTRATHECALLY INJECTED WITH VIRUS NINETEEN DAYS BEFORE OPERATION. THE PAW WITHDRAWAL MECHANICAL THRESHOLDS AND PAW WITHDRAWAL LATENCY WERE RESPECTIVELY RECORDED ONE DAY BEFORE OPERATION, THREE DAYS, FIVE DAYS AND SEVEN DAYS AFTER OPERATION. THE RATS WERE SACRIFICED ON THE SEVENTH DAY AFTER OPERATION, AND THEIR SPINAL CORD TISSUES WERE TAKEN. THE FROZEN SECTIONS OF RATS WERE PERFORMED TO OBSERVE THE EXPRESSION OF GREEN FLUORESCENT PROTEIN OF THE VIRUS. THE METHYLATION LEVEL OF RNA, THE PROTEIN EXPRESSION OF M(6)A-RELATED ENZYME (METTL3) AND MU OPIOID RECEPTOR (MOR) IN SPINAL CORD TISSUES OF THE FOUR GROUPS WERE MEASURED. DOWNREGULATION OF METTL3 HAD NO EFFECT ON THE OVERALL METHYLATION LEVEL OF THE SPINAL CORD, BUT IT COULD REGULATE THE METHYLATION LEVEL OF THE OPRM1 GENE RNA ENCODING MOR, PARTIALLY RESTORE THE EXPRESSION OF MOR, AND RELIEVE PAIN IN RATS. IN THE PROCESS OF NPP, METTL3 MAY INHIBIT THE EXPRESSION OF MOR BY REGULATING THE METHYLATION LEVEL OF OPRM1 GENE RNA ENCODING MOR, AND ULTIMATELY PROMOTE THE OCCURRENCE AND DEVELOPMENT OF NPP. 2023 9 2300 42 EPIGENETIC REGULATION OF BDNF EXPRESSION IN THE PRIMARY SENSORY NEURONS AFTER PERIPHERAL NERVE INJURY: IMPLICATIONS IN THE DEVELOPMENT OF NEUROPATHIC PAIN. BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) IS KNOWN TO BE UP-REGULATED IN THE DORSAL ROOT GANGLION (DRG) AFTER PERIPHERAL NERVE INJURY, AND TO CONTRIBUTE TO NEUROPATHIC PAIN. HERE, WE FOUND THAT THERMAL HYPERALGESIA AND MECHANICAL ALLODYNIA AT DAY 7 POST-INJURY WERE INHIBITED ONLY WHEN ANTI-BDNF ANTIBODY WAS INTRATHECALLY ADMINISTRATED AT DAY 2 POST-INJURY. CONSISTENT WITH BEHAVIORAL RESULTS, WESTERN BLOT ANALYSIS SHOWED THAT THE EXPRESSION LEVELS OF BDNF PROTEIN IN THE SPINAL DORSAL HORN WERE MARKEDLY INDUCED DURING EARLY STAGE POST-INJURY. MOREOVER, THE MAXIMAL INCREASE IN BDNF MRNA EXPRESSION IN THE DRG WAS OBSERVED AT DAY 1 POST-INJURY, AND SIGNIFICANTLY ELEVATED LEVELS WERE SUSTAINED FOR AT LEAST 14 DAYS. FOUR OF FIVE BDNF MRNA TRANSCRIPTS WERE UP-REGULATED AFTER NERVE INJURY, AND THE MOST INDUCIBLE TRANSCRIPT WAS EXON I. USING A CHROMATIN IMMUNOPRECIPITATION (CHIP) ASSAY, WE FOUND THAT NERVE INJURY PROMOTES HISTONE H3 AND H4 ACETYLATION, TRANSCRIPTIONALLY ACTIVE MODIFICATIONS, AT BDNF PROMOTER I AT DAY 1 POST-INJURY, AND THE LEVELS OF HISTONE ACETYLATION REMAIN ELEVATED FOR AT LEAST 7 DAYS. TAKEN TOGETHER, OUR FINDINGS SUGGEST THAT AN INITIAL INCREASE IN BDNF EXON I EXPRESSION CONTROLLED BY EPIGENETIC MECHANISMS MIGHT HAVE A CRUCIAL ROLE IN THE DEVELOPMENT OF NEUROPATHIC PAIN. 2013 10 1631 47 DNMT3A METHYLATION IN NEUROPATHIC PAIN. BACKGROUND: MU OPIOID RECEPTOR (MOR) PLAYS A CRUCIAL ROLE IN MEDIATING ANALGESIC EFFECTS OF OPIOIDS AND IS CLOSELY ASSOCIATED WITH THE PATHOLOGIES OF NEUROPATHIC PAIN. PREVIOUS STUDIES HAVE REPORTED THAT PERIPHERAL NERVE INJURY DOWNREGULATES MOR EXPRESSION, BUT THE EPIGENETIC MECHANISMS REMAIN UNKNOWN. OBJECTIVE: THEREFORE, WE INVESTIGATED DNA METHYLTRANSFERASE3A (DNMT3A) EXPRESSION OR METHYLATION CHANGES WITHIN MOR PROMOTER IN THE SPINAL CORD IN A NEUROPATHIC PAIN INDUCED BY A CHRONIC CONSTRICTION INJURY (CCI) MOUSE MODEL AND FURTHER DETERMINED WHETHER THESE INJURY-ASSOCIATED CHANGES ARE REVERSIBLE BY PHARMACOLOGICAL INTERVENTIONS. METHODS: A CCI MOUSE MODEL WAS ESTABLISHED AND TISSUE SPECIMENS OF LUMBAR SPINAL CORDS WERE COLLECTED. THE NOCICEPTION THRESHOLD WAS EVALUATED BY A MODEL HEATED 400 BASE. DNMT3A AND MOR MRNA AND PROTEIN LEVEL WERE DETECTED BY REAL-TIME-POLYMERASE CHAIN REACTION AND WESTERN BLOT, RESPECTIVELY. METHYLATION OF DNMT3A GENE WAS MEASURED BY METHYLATION-SPECIFIC PCR. RESULTS: OUR DATA SHOWED THAT CHRONIC NERVE INJURY LED TO A SIGNIFICANT UPREGULATION OF DNMT3A EXPRESSION THAT WAS ASSOCIATED WITH INCREASED METHYLATION OF MOR GENE PROMOTER AND DECREASED MOR PROTEIN EXPRESSION IN THE SPINAL CORD. INHIBITION OF DNMT3A CATALYTIC ACTIVITY WITH DNMT INHIBITOR RG108 SIGNIFICANTLY BLOCKED THE INCREASE IN METHYLATION OF THE MOR PROMOTER, AND THEN UPREGULATED MOR EXPRESSION AND ATTENUATED THERMAL HYPERALGESIA IN NEUROPATHIC PAIN MICE. CONCLUSION: THIS STUDY DEMONSTRATES THAT AN INCREASE OF DNMT3A EXPRESSION AND MOR METHYLATION EPIGENETICALLY PLAY AN IMPORTANT ROLE IN NEUROPATHIC PAIN. TARGETING DNMT3A TO THE PROMOTER OF MOR GENE BY DNMT INHIBITOR MAY BE A PROMISING APPROACH TO THE DEVELOPMENT OF NEW NEUROPATHIC PAIN THERAPY. 2017 11 5851 51 SUBEROYLANILIDE HYDROXAMIC ACID TRIGGERS AUTOPHAGY BY INFLUENCING THE MTOR PATHWAY IN THE SPINAL DORSAL HORN IN A RAT NEUROPATHIC PAIN MODEL. HISTONE ACETYLATION LEVELS CAN BE UPREGULATED BY TREATING CELLS WITH HISTONE DEACETYLASE INHIBITORS (HDACIS), WHICH CAN INDUCE AUTOPHAGY. AUTOPHAGY FLUX IN THE SPINAL CORD OF RATS FOLLOWING THE LEFT FIFTH LUMBER SPINAL NERVE LIGATION (SNL) IS INVOLVED IN THE PROGRESSION OF NEUROPATHIC PAIN. SUBEROYLANILIDE HYDROXAMIC ACID (SAHA), ONE OF THE HDACIS CAN INTERFERE WITH THE EPIGENETIC PROCESS OF HISTONE ACETYLATION, WHICH HAS BEEN SHOWN TO EASE NEUROPATHIC PAIN. RECENT RESEARCH SUGGEST THAT SAHA CAN STIMULATE AUTOPHAGY VIA THE MAMMALIAN TARGET OF RAPAMYCIN (MTOR) PATHWAY IN SOME TYPES OF CANCER CELLS. HOWEVER, LITTLE IS KNOWN ABOUT THE ROLE OF SAHA AND AUTOPHAGY IN NEUROPATHIC PAIN AFTER NERVE INJURY. IN THE PRESENT STUDY, WE AIM TO INVESTIGATE AUTOPHAGY FLUX AND THE ROLE OF THE MTOR PATHWAY ON SPINAL CELLS AUTOPHAGY ACTIVATION IN NEUROPATHIC PAIN INDUCED BY SNL IN RATS THAT RECEIVED SAHA TREATMENT. AUTOPHAGY-RELATED PROTEINS AND MTOR OR ITS ACTIVE FORM WERE ASSESSED BY USING WESTERN BLOT, IMMUNOHISTOCHEMISTRY, DOUBLE IMMUNOFLUORESCENCE STAINING AND TRANSMISSION ELECTRON MICROSCOPY (TEM). WE FOUND THAT SAHA DECREASED THE PAW MECHANICAL WITHDRAWAL THRESHOLD (PMWT) OF THE LOWER COMPARED WITH SNL. AUTOPHAGY FLUX WAS MAINLY DISRUPTED IN THE ASTROCYTES AND NEURONAL CELLS OF THE SPINAL CORD DORSAL HORN ON POSTSURGICAL DAY 28 AND WAS REVERSED BY DAILY INTRATHECAL INJECTION OF SAHA (N = 100 NMOL/DAY OR N = 200 NMOL/DAY). SAHA ALSO DECREASED MTOR AND PHOSPHORYLATED MTOR (P-MTOR) EXPRESSION, ESPECIALLY P-MTOR EXPRESSION IN ASTROCYTES AND NEURONAL CELLS OF THE SPINAL DORSAL HORN. THESE RESULTS SUGGEST THAT SAHA ATTENUATES NEUROPATHIC PAIN AND CONTRIBUTES TO AUTOPHAGY FLUX IN ASTROCYTES AND NEURONAL CELLS OF THE SPINAL DORSAL HORN VIA THE MTOR SIGNALING PATHWAY. 2019 12 3809 40 INTRAPERITONEAL 5-AZACYTIDINE ALLEVIATES NERVE INJURY-INDUCED PAIN IN RATS BY MODULATING DNA METHYLATION. TO INVESTIGATE THE ROLE OF DNA METHYLATION IN MODULATING CHRONIC NEUROPATHIC PAIN (NPP), IDENTIFY POSSIBLE TARGET GENES OF DNA METHYLATION INVOLVED IN THIS PROCESS, AND PRELIMINARILY CONFIRM THE MEDICINAL VALUE OF THE DNA METHYLTRANSFERASES (DNMTS) INHIBITOR 5-AZACYTIDINE (5-AZA) IN NPP BY TARGETING GENE METHYLATION. TWO RAT NPP MODELS, CHRONIC CONSTRICTION INJURY (CCI) AND SPINAL NERVE LIGATION (SNL), WERE USED. THE DNA METHYLATION PROFILES IN THE LUMBAR SPINAL CORD WERE ASSAYED USING AN ARRAYSTAR RAT REFSEQ PROMOTER ARRAY. THE UNDERLYING GENES WITH DIFFERENTIAL METHYLATION WERE THEN IDENTIFIED AND SUBMITTED TO GENE ONTOLOGY AND PATHWAY ANALYSIS. METHYL-DNA IMMUNOPRECIPITATION QUANTITATIVE PCR (MEDIP-QPCR) AND QUANTITATIVE REVERSE TRANSCRIPTION-PCR (RT-QPCR) WERE USED TO CONFIRM GENE METHYLATION AND EXPRESSION. THE PROTECTIVE FUNCTION OF 5-AZA IN NPP AND GENE EXPRESSION WERE EVALUATED VIA BEHAVIORAL ASSAYS AND RT-QPCR, RESPECTIVELY. ANALYSIS OF THE DNA METHYLATION PATTERNS IN THE LUMBAR SPINAL CORD INDICATED THAT 1205 DIFFERENTIALLY METHYLATED FRAGMENTS IN CCI RATS WERE LOCATED WITHIN DNA PROMOTER REGIONS, INCLUDING 638 HYPERMETHYLATED FRAGMENTS AND 567 HYPOMETHYLATED FRAGMENTS. THE METHYLATION LEVELS OF GRM4, HTR4, ADRB2, KCNF1, GAD2, AND PPARG, WHICH ARE ASSOCIATED WITH LONG-TERM POTENTIATION (LTP) AND GLUTAMATERGIC SYNAPSE PATHWAYS, WERE INCREASED WITH A CORRESPONDING DECREASE IN THEIR MRNA EXPRESSION, IN THE SPINAL CORDS OF CCI RATS. MOREOVER, WE FOUND THAT THE INTRAPERITONEAL INJECTION OF 5-AZA (4 MG/KG) ATTENUATED CCI- OR SNL-INDUCED MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA. FINALLY, THE MRNA EXPRESSION OF HYPERMETHYLATED GENES SUCH AS GRM4, HTR4, ADRB2, KCNF1, AND GAD2 WAS REVERSED AFTER 5-AZA TREATMENT. CCI INDUCED WIDESPREAD METHYLATION CHANGES IN THE DNA PROMOTER REGIONS IN THE LUMBAR SPINAL CORD. INTRAPERITONEAL 5-AZA ALLEVIATED HYPERALGESIA IN CCI AND SNL RATS, AN EFFECT ACCOMPANIED BY THE REVERSED EXPRESSION OF HYPERMETHYLATED GENES. THUS, DNA METHYLATION INHIBITION REPRESENTS A PROMISING EPIGENETIC STRATEGY FOR PROTECTION AGAINST CHRONIC NPP FOLLOWING NERVE INJURY. OUR STUDY LAYS A THEORETICAL FOUNDATION FOR 5-AZA TO BECOME A CLINICAL TARGETED DRUG. 2023 13 3324 54 HISTONE DEACETYLASE 2 IS INVOLVED IN MICRO?OPIOID RECEPTOR SUPPRESSION IN THE SPINAL DORSAL HORN IN A RAT MODEL OF CHRONIC PANCREATITIS PAIN. CHRONIC PAIN OCCURS IN ~85-90% OF CHRONIC PANCREATITIS (CP) PATIENTS. HOWEVER, AS THE PATHOGENESIS OF CP PAIN REMAINS TO BE FULLY UNDERSTOOD, THE CURRENT THERAPIES FOR CP PAIN REMAIN INADEQUATE. EMERGING EVIDENCE HAS SUGGESTED THAT THE EPIGENETIC MODULATIONS OF GENES ARE INVOLVED IN CHRONIC PAIN. IN THE PRESENT STUDY, INTRAPANCREATIC TRINITROBENZENE SULFONIC ACID INFUSIONS WERE USED TO ESTABLISH A CP MODEL IN RATS. MECHANICAL ALLODYNIA WAS MEASURED WITH VON FREY FILAMENTS. IMMUNOFLUORESCENT STAINING ANALYSIS WAS USED TO OBSERVE THE EXPRESSION CHANGES OF HISTONE DEACETYLASE 2 (HDAC2) AND MICRO?OPIOID RECEPTOR (MOR), AND INTRATHECAL ADMINISTRATION OF THE SELECTIVE HDAC2 INHIBITOR AR?42 WAS USED TO ASSESS THE UNDERLYING MECHANISMS. THE EXPRESSION LEVELS OF C?JUN N?TERMINAL KINASE (JNK) IN THE THORACIC SPINAL CORD WERE DETECTED BY WESTERN BLOTTING, AND THE MRNA EXPRESSION LEVELS OF INTERLEUKIN (IL)1?BETA, IL?6 AND TUMOR NECROSIS FACTOR (TNF)?ALPHA WERE DETECTED BY REVERSE TRANSCRIPTION?QUANTITATIVE POLYMERASE CHAIN REACTION. THE RESULTS DEMONSTRATED THAT HDAC2 EXPRESSION WAS UPREGULATED DURING THE COURSE OF CP INDUCTION, WHILE MOR ACTIVITY IN THE THORACIC SPINAL DORSAL HORN WAS SIGNIFICANTLY SUPPRESSED. INTRATHECAL INFUSION OF AR?42 SIGNIFICANTLY ATTENUATED CP?INDUCED MECHANICAL ALLODYNIA, WITH RESCUED MOR ACTIVITY. ADDITIONALLY, HDAC2 FACILITATED THE RELEASE OF INFLAMMATORY CYTOKINES, INCLUDING IL?1BETA, IL?6 AND TNF?ALPHA. THESE RESULTS SUGGESTED THAT THE UNDERLYING MECHANISMS OF HDAC2 REGULATING MOR ACTIVITY UNDER CP INDUCTION MAY OCCUR VIA PROMOTING THE RELEASE OF INFLAMMATORY CYTOKINES, THUS ACTIVATING THE JNK SIGNALING PATHWAY. THE PRESENT STUDY SUGGESTED THAT THE EPIGENETIC?REGULATED DISTURBANCE OF MOR IS DEPENDENT ON THE ENDOGENOUS ANALGESIA SYSTEM IN CP, WHICH MAY A PROVIDE NOVEL THERAPEUTIC STRATEGY FOR TREATING PAIN IN CP. 2018 14 6660 40 UPREGULATION OF CXCR4 THROUGH PROMOTER DEMETHYLATION CONTRIBUTES TO INFLAMMATORY HYPERALGESIA IN RATS. AIM AND METHODS: CHRONIC PAIN ASSOCIATED WITH INFLAMMATION IS A COMMON CLINICAL PROBLEM, AND THE UNDERLYING MECHANISMS YET ARE INCOMPLETELY DEFINED. DNA METHYLATION HAS BEEN IMPLICATED IN THE PATHOGENESIS OF CHRONIC PAIN. HOWEVER, THE SPECIFIC GENES REGULATED BY DNA METHYLATION UNDER INFLAMMATORY PAIN CONDITION REMAIN LARGELY UNKNOWN. HERE, WE INVESTIGATED HOW CHEMOKINE RECEPTOR CXCR4 EXPRESSION IS REGULATED BY DNA METHYLATION AND HOW IT CONTRIBUTES TO INFLAMMATORY PAIN INDUCED BY COMPLETE FREUND'S ADJUVANT (CFA) IN RATS. RESULTS: INTRAPLANTAR INJECTION OF CFA COULD NOT ONLY INDUCE SIGNIFICANT HYPERALGESIA IN RATS, BUT ALSO SIGNIFICANTLY INCREASE THE EXPRESSION OF CXCR4 MRNA AND PROTEIN IN THE DORSAL ROOT GANGLION (DRG). INTRATHECAL INJECTION OF CXCR4 ANTAGONIST AMD3100 SIGNIFICANTLY RELIEVED HYPERALGESIA IN INFLAMMATORY RATS IN A TIME- AND DOSE-DEPENDENT MANNER. BISULFITE SEQUENCING AND METHYLATION-SPECIFIC PCR DEMONSTRATE THAT CFA INJECTION LED TO A SIGNIFICANT DEMETHYLATION OF CPG ISLAND AT CXCR4 GENE PROMOTER. CONSISTENTLY, THE EXPRESSION OF DNMT3B WAS SIGNIFICANTLY DOWNREGULATED AFTER CFA INJECTION. ONLINE SOFTWARE PREDICTION REVEALS THREE BINDING SITES OF P65 IN THE CPG ISLAND OF CXCR4 GENE PROMOTER, WHICH HAS CONFIRMED BY THE CHROMATIN IMMUNOPRECIPITATION ASSAY, CFA TREATMENT SIGNIFICANTLY INCREASES THE RECRUITMENT OF P65 TO CXCR4 GENE PROMOTER. INHIBITION OF NF-KB SIGNALING USING P65 INHIBITOR PYRROLIDINE DITHIOCARBAMATE SIGNIFICANTLY PREVENTED THE INCREASES OF THE CXCR4 EXPRESSION. CONCLUSION: UPREGULATION OF CXCR4 EXPRESSION DUE TO PROMOTER DEMETHYLATION FOLLOWED BY INCREASED RECRUITMENT OF P65 TO PROMOTER OF CXCR4 GENE CONTRIBUTES TO INFLAMMATORY HYPERALGESIA. THESE FINDINGS PROVIDE A THEORETICAL BASIS FOR THE TREATMENT OF CHRONIC PAIN FROM AN EPIGENETIC PERSPECTIVE. 2018 15 3194 37 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 16 6461 45 TIME-COURSE PROGRESSION OF WHOLE TRANSCRIPTOME EXPRESSION CHANGES OF TRIGEMINAL GANGLIA COMPARED TO DORSAL ROOT GANGLIA IN RATS EXPOSED TO NERVE INJURY. MECHANISMS UNDERLYING NEUROPATHIC PAIN (NP) ARE COMPLEX WITH MULTIPLE GENES, THEIR INTERACTIONS, ENVIRONMENTAL AND EPIGENETIC FACTORS BEING IMPLICATED. TRANSCRIPTIONAL CHANGES IN THE TRIGEMINAL (TG) AND DORSAL ROOT (DRG) GANGLIA HAVE BEEN IMPLICATED IN THE DEVELOPMENT AND MAINTENANCE OF NP. DESPITE EFFORTS TO UNRAVEL MOLECULAR MECHANISMS OF NP, MANY REMAIN UNKNOWN. ALSO, MOST OF THE STUDIES FOCUSED ON THE SPINAL SYSTEM. ALTHOUGH THE SPINAL AND TRIGEMINAL SYSTEMS SHARE SOME OF THE MOLECULAR MECHANISMS, DIFFERENCES EXIST. WE USED RNA-SEQUENCING TECHNOLOGY TO IDENTIFY DIFFERENTIALLY EXPRESSED GENES (DEGS) IN THE TG AND DRG AT BASELINE AND 3 TIME-POINTS FOLLOWING THE INFRAORBITAL OR SCIATIC NERVE INJURIES, RESPECTIVELY. PATHWAY ANALYSIS AND COMPARISON ANALYSIS WERE PERFORMED TO IDENTIFY DIFFERENTIALLY EXPRESSED PATHWAYS. ADDITIONALLY, UPSTREAM REGULATOR EFFECTS WERE INVESTIGATED IN THE TWO SYSTEMS. DEG (DIFFERENTIALLY EXPRESSED GENES) ANALYSES IDENTIFIED 3,225 GENES TO BE DIFFERENTIALLY EXPRESSED BETWEEN TG AND DRG IN NAIVE ANIMALS, 1,828 GENES FOUR DAYS POST INJURY, 5,644 AT DAY 8 AND 9,777 DEGS AT 21 DAYS POST INJURY. COMPARISON OF TOP ENRICHED CANONICAL PATHWAYS REVEALED THAT A NUMBER OF SIGNALING PATHWAY WAS SIGNIFICANTLY INHIBITED IN THE TG AND ACTIVATED IN THE DRG AT 21 DAYS POST INJURY. FINALLY, CORT UPSTREAM REGULATOR WAS PREDICTED TO BE INHIBITED IN THE TG WHILE EXPRESSION LEVELS OF CSF1 UPSTREAM REGULATOR WERE SIGNIFICANTLY ELEVATED IN THE DRG AT 21 DAYS POST INJURY. THIS STUDY PROVIDES A BASIS FOR FURTHER IN-DEPTH STUDIES INVESTIGATING TRANSCRIPTIONAL CHANGES, PATHWAYS, AND UPSTREAM REGULATION IN TG AND DRG IN RATS EXPOSED TO PERIPHERAL NERVE INJURIES. 2023 17 6172 48 THE HDAC1/C-JUN COMPLEX IS ESSENTIAL IN THE PROMOTION OF NERVE INJURY-INDUCED NEUROPATHIC PAIN THROUGH JNK SIGNALING. 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. ADMINISTRATION OF A SELECTIVE HDAC1 INHIBITOR (LG325) IN SNI-SUBJECTED MICE SIGNIFICANTLY ATTENUATED BEHAVIOR RELATED TO INJURY-INDUCED PAIN. UNDERSTANDING THE HDAC1 PATHWAY IN EPIGENETIC REGULATION OF PATHOLOGICAL PAIN IS OF GREAT MEDICAL RELEVANCE. SPARED NERVE INJURY (SNI) MICE SHOWED A SIGNIFICANT INCREASE IN THE HDAC1 PROTEIN LEVELS WITHIN SPINAL CORD IN COINCIDENCE WITH THE NOCICEPTIVE PHENOTYPE AT 1 AND 3 WEEKS AFTER NERVE INJURY. NO VARIATION IN HDAC3, DNMT3A, ACH3, MBD3 AND MECP2 LEVELS WAS DETECTED. INCREASED EXPRESSION OF HDAC1 IS ACCOMPANIED BY ACTIVATION OF THE JNK-C-JUN SIGNALING PATHWAY. A ROBUST SPINAL JNK-1 OVERPHOSPHORYLATION WAS OBSERVED POST NERVE-INJURY ALONG WITH A SELECTIVE JNK-DEPENDENT INCREASE IN P-C-JUN AND HDAC1 PROTEIN LEVELS. CO-IMMUNOPRECIPITATION EXPERIMENTS SHOWED THE PRESENCE OF A HETERODIMERIC COMPLEX BETWEEN HDAC1 AND C-JUN IN SNI MICE INDICATING THAT THESE TRANSCRIPTION FACTORS CAN ACT TOGETHER TO REGULATE TRANSCRIPTION THROUGH HETERODIMERIZATION. STIMULATION OF C-JUN PHOSPHORYLATION WAS PREVENTED BY THE SELECTIVE HDAC1 INHIBITOR LG325. WE FOUND THAT HDAC1 WAS ASSOCIATED WITH C-JUN IN NUCLEI OF SPINAL DORSAL HORN ASTROCYTES EXPRESSING JNK. ON THE OTHER HAND, THE PRESENCE OF HDAC1 AND C-JUN INTERACTION WAS NOT DETECTED IN CONTROL MICE. THESE FINDINGS PROVIDE NEW INSIGHTS INTO THE MECHANISMS UNDERLYING THE ANTI-NOCICEPTIVE ACTIVITY OF HDAC INHIBITORS. TAKEN TOGETHER, THESE DATA SUPPORT A ROLE FOR HISTONE DEACETYLASE IN THE EMERGENCE OF NEUROPATHIC PAIN. 2018 18 2477 40 EPIGENETIC UPREGULATION OF CDK5 IN THE DORSAL HORN CONTRIBUTES TO NEUROPATHIC PAIN IN RATS. NUMEROUS REPORTS HAVE SHOWN THAT CYCLIN-DEPENDENT KINASE 5 (CDK5), A PROLINE-DIRECTED SERINE/THREONINE KINASE, CRITICALLY CONTRIBUTES TO THE INDUCTION AND MAINTENANCE OF CHRONIC PAIN INDUCED BY PERIPHERAL INFLAMMATION AND NERVE INJURY. RECENT EVIDENCE HAS ALSO SUGGESTED THE CRITICAL ROLE OF AN EPIGENETIC MECHANISM IN THE SETTING OF CHRONIC PAIN. THE PRESENT STUDY AIMS TO ELUCIDATE THE CYCLIC AMP RESPONSE ELEMENT-BINDING PROTEIN (CREB)-MEDIATED UPREGULATION OF CDK5 AND ITS FUNCTIONAL SIGNIFICANCE IN RATS WITH NEUROPATHIC PAIN INDUCED BY CHRONIC CONSTRICTION INJURY (CCI) IN THE SCIATIC NERVE. SIGNIFICANTLY INCREASED EXPRESSION OF CDK5 WAS OBSERVED IN THE DORSAL HORN OF RATS WITH CCI, AND INTRATHECAL DELIVERY OF CDK5 INHIBITOR ROSCOVITINE SIGNIFICANTLY ATTENUATED THE MECHANICAL ALLODYNIA IN THESE RATS. PHOSPHORYLATION OF CREB AND ITS OCCUPANCY IN THE CDK5 PROMOTER REGION WAS ALSO INCREASED IN THE DORSAL HORN, WHICH LED TO INCREASED HISTONE H4 ACETYLATION IN THE CDK5 PROMOTER REGION AND THE UPREGULATED TRANSCRIPTION OF CDK5. INHIBITION OF CREB ACTIVITY ATTENUATED THE UPREGULATION OF CDK5 AND ALLEVIATED THE MECHANICAL ALLODYNIA IN RATS WITH CCI. THESE RESULTS DEMONSTRATED A CREB-MEDIATED EPIGENETIC UPREGULATION OF CDK5 IN THE DORSAL HORN, WHICH CRITICALLY CONTRIBUTED TO THE MAINTENANCE OF PAINFUL BEHAVIOR IN THE RATS WITH NEUROPATHIC PAIN. 2014 19 3082 43 GENOME-WIDE REDISTRIBUTION OF MECP2 IN DORSAL ROOT GANGLIA AFTER PERIPHERAL NERVE INJURY. BACKGROUND: METHYL-CPG-BINDING PROTEIN 2 (MECP2), A PROTEIN WITH AFFINITY FOR METHYLATED CYTOSINES, IS CRUCIAL FOR NEURONAL DEVELOPMENT AND FUNCTION. MECP2 REGULATES GENE EXPRESSION THROUGH ACTIVATION, REPRESSION AND CHROMATIN REMODELING. MUTATIONS IN MECP2 CAUSE RETT SYNDROME, AND THESE PATIENTS DISPLAY IMPAIRED NOCICEPTION. WE OBSERVED AN INCREASE IN MECP2 EXPRESSION IN MOUSE DORSAL ROOT GANGLIA (DRG) AFTER PERIPHERAL NERVE INJURY. THE FUNCTIONAL IMPLICATION OF INCREASED MECP2 IS LARGELY UNKNOWN. TO IDENTIFY REGIONS OF THE GENOME BOUND BY MECP2 IN THE DRG AND THE CHANGES INDUCED BY NERVE INJURY, A CHROMATIN IMMUNOPRECIPITATION OF MECP2 FOLLOWED BY SEQUENCING (CHIP-SEQ) WAS PERFORMED 4 WEEKS AFTER SPARED NERVE INJURY (SNI). RESULTS: WHILE THE NUMBER OF BINDING SITES ACROSS THE GENOME REMAINED SIMILAR IN THE SNI MODEL AND SHAM CONTROL, SNI INDUCED THE REDISTRIBUTION OF MECP2 TO TRANSCRIPTIONALLY RELEVANT REGIONS. TO DETERMINE HOW DIFFERENTIAL BINDING OF MECP2 CAN AFFECT GENE EXPRESSION IN THE DRG, WE INVESTIGATED MMU-MIR-126, A MICRORNA LOCUS THAT HAD ENRICHED MECP2 BINDING IN THE SNI MODEL. ENRICHED MECP2 BINDING TO MIR-126 LOCUS AFTER NERVE INJURY REPRESSED MIR-126 EXPRESSION, AND THIS WAS NOT MEDIATED BY ALTERATIONS IN METHYLATION PATTERN AT THE MIR-126 LOCUS. DOWNREGULATION OF MIR-126 RESULTED IN THE UPREGULATION OF ITS TWO TARGET GENES DNMT1 AND VEGFA IN NEURO 2A CELLS AND IN SNI MODEL COMPARED TO CONTROL. THESE TARGET GENES WERE SIGNIFICANTLY DOWNREGULATED IN MECP2-NULL MICE COMPARED TO WILD-TYPE LITTERMATES, INDICATING A REGULATORY ROLE FOR MECP2 IN ACTIVATING DNMT1 AND VEGFA EXPRESSION. INTRATHECAL DELIVERY OF MIR-126 WAS NOT SUFFICIENT TO REVERSE NERVE INJURY-INDUCED MECHANICAL AND THERMAL HYPERSENSITIVITY, BUT DECREASED DNMT1 AND VEGFA EXPRESSION IN THE DRG. CONCLUSIONS: OUR STUDY SHOWS A REGULATORY ROLE FOR MECP2 IN THAT CHANGES IN GLOBAL REDISTRIBUTION CAN RESULT IN DIRECT AND INDIRECT MODULATION OF GENE EXPRESSION IN THE DRG. ALTERATIONS IN GENOME-WIDE BINDING OF MECP2 THEREFORE PROVIDE A MOLECULAR BASIS FOR A BETTER UNDERSTANDING OF EPIGENETIC REGULATION-INDUCED MOLECULAR CHANGES UNDERLYING NERVE INJURY. 2016 20 717 60 CALCITONIN GENE-RELATED PEPTIDE REGULATES SPINAL MICROGLIAL ACTIVATION THROUGH THE HISTONE H3 LYSINE 27 TRIMETHYLATION VIA ENHANCER OF ZESTE HOMOLOG-2 IN RATS WITH NEUROPATHIC PAIN. BACKGROUND: CALCITONIN GENE-RELATED PEPTIDE (CGRP) AS A MEDIATOR OF MICROGLIAL ACTIVATION AT THE TRANSCRIPTIONAL LEVEL MAY FACILITATE NOCICEPTIVE SIGNALING. TRIMETHYLATION OF H3 LYSINE 27 (H3K27ME3) BY ENHANCER OF ZESTE HOMOLOG 2 (EZH2) IS AN EPIGENETIC MARK THAT REGULATES INFLAMMATORY-RELATED GENE EXPRESSION AFTER PERIPHERAL NERVE INJURY. IN THIS STUDY, WE EXPLORED THE RELATIONSHIP BETWEEN CGRP AND H3K27ME3 IN MICROGLIAL ACTIVATION AFTER NERVE INJURY, AND ELUCIDATED THE UNDERLYING MECHANISMS IN THE PATHOGENESIS OF CHRONIC NEUROPATHIC PAIN. METHODS: MICROGLIAL CELLS (BV2) WERE TREATED WITH CGRP AND DIFFERENTIALLY ENRICHMENTS OF H3K27ME3 ON GENE PROMOTERS WERE EXAMINED USING CHIP-SEQ. A CHRONIC CONSTRICTION INJURY (CCI) RAT MODEL WAS USED TO EVALUATE THE ROLE OF CGRP ON MICROGLIAL ACTIVATION AND EZH2/H3K27ME3 SIGNALING IN CCI-INDUCED NEUROPATHIC PAIN. RESULTS: OVEREXPRESSIONS OF EZH2 AND H3K27ME3 WERE CONFIRMED IN SPINAL MICROGLIA OF CCI RATS BY IMMUNOFLUORESCENCE. CGRP TREATMENT INDUCED THE INCREASED OF H3K27ME3 EXPRESSION IN THE SPINAL DORSAL HORN AND CULTURED MICROGLIAL CELLS (BV2) THROUGH EZH2. CHIP-SEQ DATA INDICATED THAT CGRP SIGNIFICANTLY ALTERED H3K27ME3 ENRICHMENTS ON GENE PROMOTERS IN MICROGLIA FOLLOWING CGRP TREATMENT, INCLUDING 173 GAINING H3K27ME3 AND 75 LOSING THIS MARK, WHICH MOSTLY ENRICHED IN REGULATION OF CELL GROWTH, PHAGOSOME, AND INFLAMMATION. QRT-PCR VERIFIED EXPRESSIONS OF REPRESENTATIVE CANDIDATE GENES (TRAF3IP2, BCL2L11, ITGAM, DAB2, NLRP12, WNT3, ADAM10) AND REAL-TIME CELL ANALYSIS (RTCA) VERIFIED MICROGLIAL PROLIFERATION. ADDITIONALLY, CGRP TREATMENT AND CCI INCREASED EXPRESSIONS OF ITGAM, ADAM10, MCP-1, AND CX3CR1, KEY MEDIATORS OF MICROGLIAL ACTIVATION IN SPINAL DORSAL HORN AND CULTURED MICROGLIAL CELLS. SUCH INCREASED EFFECTS INDUCED BY CCI WERE SUPPRESSED BY CGRP ANTAGONIST AND EZH2 INHIBITOR, WHICH WERE CONCURRENTLY ASSOCIATED WITH THE ATTENUATED MECHANICAL AND THERMAL HYPERALGESIA IN CCI RATS. CONCLUSION: OUR FINDINGS HIGHLY INDICATE THAT CGRP IS IMPLICATED IN THE GENESIS OF NEUROPATHIC PAIN THROUGH REGULATING MICROGLIAL ACTIVATION VIA EZH2-MEDIATED H3K27ME3 IN THE SPINAL DORSAL HORN. 2021