1 2479 116 EPIGENETIC UPREGULATION OF CXCL12 EXPRESSION MEDIATES ANTITUBULIN CHEMOTHERAPEUTICS-INDUCED NEUROPATHIC PAIN. CLINICALLY, MICROTUBULE-TARGETED AGENTS-INDUCED NEUROPATHIC PAIN HAMPERS CHEMOTHERAPEUTICS FOR PATIENTS WITH CANCER. HERE, WE FOUND THAT APPLICATION OF PACLITAXEL OR VINCRISTINE INCREASED THE PROTEIN AND MRNA EXPRESSION OF CXCL12 AND FREQUENCY AND AMPLITUDE OF MINIATURE EXCITATORY POST SYNAPTIC CURRENTS (MEPSCS) IN SPINAL DORSAL HORN NEURONS. SPINAL LOCAL APPLICATION OF CXCL12 INDUCED THE LONG-TERM POTENTIATION OF NOCICEPTIVE SYNAPTIC TRANSMISSION AND INCREASED THE AMPLITUDE OF MEPSCS. INHIBITION OF CXCL12 USING THE TRANSGENIC MICE (CXCL12) OR NEUTRALIZING ANTIBODY OR SIRNA AMELIORATED THE MEPSC'S ENHANCEMENT AND MECHANICAL ALLODYNIA. IN ADDITION, PACLITAXEL AND VINCRISTINE BOTH COULD INCREASE THE PHOSPHORYLATION OF SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION 3 (STAT3) AND THE ACETYLATION OF HISTONE H4 IN THE CXCL12-EXPRESSING NEURONS. IMMUNOPRECIPITATION AND CHROMATIN IMMUNOPRECIPITATION ASSAYS DEMONSTRATED THAT ANTITUBULIN CHEMOTHERAPEUTICS INCREASED THE BINDING OF STAT3 TO THE CXCL12 GENE PROMOTER AND THE INTERACTION BETWEEN STAT3 AND P300, AND CONTRIBUTED TO THE ENHANCED TRANSCRIPTION OF CXCL12 BY INCREASING THE ACETYLATION OF HISTONE H4 IN CXCL12 GENE PROMOTER. INHIBITION OF STAT3 BY INTRATHECAL INJECTION OF ADENO-ASSOCIATED VIRUS ENCODING CRE AND GREEN FLUORESCENT PROTEIN INTO STAT3 MICE OR INHIBITOR S3I-201 INTO RATS SUPPRESSED THE CXCL12 UPSURGE BY DECREASING THE ACETYLATION OF HISTONE H4. FINALLY, BLOCKADE OF CXCR4 BUT NOT CXCR7 AMELIORATED THE PACLITAXEL- OR VINCRISTINE-INDUCED MECHANICAL ALLODYNIA. TOGETHER, THESE RESULTS SUGGESTED THAT ENHANCED INTERACTION BETWEEN STAT3 AND P300 MEDIATED THE EPIGENETIC UPREGULATION OF CXCL12 IN DORSAL HORN NEURONS, WHICH CONTRIBUTED TO THE ANTITUBULIN CHEMOTHERAPEUTICS-INDUCED PERSISTENT PAIN. 2017 2 5514 20 RICHTER'S SYNDROME: BIOLOGY AND THERAPY. RICHTER'S SYNDROME, THAT IS, TRANSFORMATION OF CHRONIC LYMPHOCYTIC LEUKEMIA TO A LARGE CELL OR IMMUNOBLASTIC LYMPHOMA, OCCURS IN UP TO 10% OF PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA. THE ONSET OF RICHTER'S SYNDROME IS CHARACTERIZED BY WORSENING SYSTEMIC SYMPTOMS, RAPID TUMOR GROWTH, AND/OR EXTRANODAL INVOLVEMENT. MEDIAN SURVIVAL WITH CONVENTIONAL CHEMOTHERAPY IS LESS THAN 6 MONTHS. THERAPY WITH MORE RECENT THERAPEUTIC REGIMENS, SUCH AS HYPERCVXD (FRACTIONATED CYCLOPHOSPHAMIDE, VINCRISTINE, LIPOSOMAL DAUNORUBICIN, AND DEXAMETHASONE), AUGMENTED HYPERCVXD, AND YTTRIUM-90 IBRITUMOMAB TIUXETAN, HAS NOT PRODUCED MAJOR IMPROVEMENTS IN RESPONSE RATES OR OVERALL SURVIVAL. IMPROVEMENT IN THE OUTCOME OF PATIENTS WITH RICHTER'S SYNDROME MAY BE AIDED BY A MORE COMPREHENSIVE UNDERSTANDING OF THE PATHOGENESIS OF RICHTER'S SYNDROME; THERAPY COULD THEN BE TARGETED AGAINST SPECIFIC ABNORMALITIES. CURRENT DATA INDICATE THAT THE TRANSFORMATION OF CHRONIC LYMPHOCYTIC LEUKEMIA TO A LARGE-CELL OR IMMUNOBLASTIC LYMPHOMA IS ASSOCIATED WITH ABNORMALITIES IN CELL CYCLE REGULATION (E.G., LOSS OF THE CELL CYCLE INHIBITORS P16(INK4A) AND P27(KIP1) ) AND DNA REPAIR (E.G., MUTATIONS AND/OR DELETIONS OF THE P53, ATM, AND P14(ARF) GENES AND EPIGENETIC SILENCING OF THE MLH1 GENE). HOWEVER, THE CRITICAL EVENT LEADING TO TRANSFORMATION IS UNCLEAR. GIVEN THE POOR PROGNOSIS OF PATIENTS WITH RICHTER'S SYNDROME, EVERY EFFORT SHOULD BE MADE TO ENROLL THESE PATIENTS INTO CLINICAL TRIALS EVALUATING NOVEL AGENTS WITH THE APPROPRIATE CORRELATIVE STUDIES. 2005 3 4172 30 MELATONIN IMPEDES TET1-DEPENDENT MGLUR5 PROMOTER DEMETHYLATION TO RELIEVE PAIN. MELATONIN (N-ACETYL-5-METHOXYTRYPTAMINE)/MT2 RECEPTOR-DEPENDENT EPIGENETIC MODIFICATION REPRESENTS A NOVEL PATHWAY IN THE TREATMENT OF NEUROPATHIC PAIN. BECAUSE SPINAL TEN-ELEVEN TRANSLOCATION METHYLCYTOSINE DIOXYGENASE 1 (TET1)-DEPENDENT EPIGENETIC DEMETHYLATION HAS RECENTLY BEEN LINKED TO PAIN HYPERSENSITIVITY, WE HYPOTHESIZED THAT MELATONIN/MT2-DEPENDENT ANALGESIA INVOLVES SPINAL TET1-DEPENDENT DEMETHYLATION. HERE, WE SHOWED THAT SPINAL TET1 GENE TRANSFER BY INTRATHECAL DELIVERY OF TET1-ENCODING VECTORS TO NAIVE RATS PRODUCED PROFOUND AND LONG-LASTING NOCICEPTIVE HYPERSENSITIVITY. IN ADDITION, ENHANCED TET1 EXPRESSION, TET1-METABOTROPIC GLUTAMATE RECEPTOR SUBTYPE 5 (MGLUR5) PROMOTER COUPLING, DEMETHYLATION AT THE MGLUR5 PROMOTER, AND MGLUR5 EXPRESSION IN DORSAL HORN NEURONS WERE OBSERVED. RATS SUBJECTED TO SPINAL NERVE LIGATION AND INTRAPLANTAR COMPLETE FREUND'S ADJUVANT INJECTION DISPLAYED TACTILE ALLODYNIA AND BEHAVIORAL HYPERALGESIA ASSOCIATED WITH SIMILAR CHANGES IN THE DORSAL HORN. NOTABLY, INTRATHECAL MELATONIN INJECTION REVERSED THE PROTEIN EXPRESSION, PROTEIN-PROMOTER COUPLING, PROMOTER DEMETHYLATION, AND PAIN HYPERSENSITIVITY INDUCED BY TET1 GENE TRANSFER, SPINAL NERVE LIGATION, AND INTRAPLANTAR COMPLETE FREUND'S ADJUVANT INJECTION. ALL THE EFFECTS CAUSED BY MELATONIN WERE BLOCKED BY PRETREATMENT WITH A MT2 RECEPTOR-SELECTIVE ANTAGONIST. IN CONCLUSION, MELATONIN RELIEVES PAIN BY IMPEDING TET1-DEPENDENT DEMETHYLATION OF MGLUR5 IN DORSAL HORN NEURONS THROUGH THE MT2 RECEPTOR. OUR FINDINGS LINK MELATONIN/MT2 SIGNALING TO TET1-DEPENDENT EPIGENETIC DEMETHYLATION OF NOCICEPTIVE GENES FOR THE FIRST TIME AND SUGGEST MELATONIN AS A PROMISING THERAPY FOR THE TREATMENT OF PAIN. 2017 4 4699 47 NFATC2-DEPENDENT EPIGENETIC UPREGULATION OF CXCL14 IS INVOLVED IN THE DEVELOPMENT OF NEUROPATHIC PAIN INDUCED BY PACLITAXEL. BACKGROUND: THE MAJOR DOSE-LIMITING TOXICITY OF PACLITAXEL, ONE OF THE MOST COMMONLY USED DRUGS TO TREAT SOLID TUMOR, IS PAINFUL NEUROPATHY. HOWEVER, THE MOLECULAR MECHANISMS UNDERLYING PACLITAXEL-INDUCED PAINFUL NEUROPATHY ARE LARGELY UNCLARIFIED. METHODS: PAW WITHDRAWAL THRESHOLD WAS MEASURED IN THE RATS FOLLOWING INTRAPERITONEAL INJECTION OF PACLITAXEL. THE QPCR, WESTERN BLOTTING, PROTEIN OR CHROMATIN IMMUNOPRECIPITATION, CHIP-SEQ IDENTIFICATION OF NFATC2 BINDING SITES, AND MICROARRAY ANALYSIS WERE PERFORMED TO EXPLORE THE MOLECULAR MECHANISM. RESULTS: WE FOUND THAT PACLITAXEL TREATMENT INCREASED THE NUCLEAR EXPRESSION OF NFATC2 IN THE SPINAL DORSAL HORN, AND KNOCKDOWN OF NFATC2 WITH NFATC2 SIRNA SIGNIFICANTLY ATTENUATED THE MECHANICAL ALLODYNIA INDUCED BY PACLITAXEL. FURTHER BINDING SITE ANALYSIS UTILIZING CHIP-SEQ ASSAY COMBINING WITH GENE EXPRESSION PROFILE REVEALED A SHIFT OF NFATC2 BINDING SITE CLOSER TO TTS OF TARGET GENES IN DORSAL HORN AFTER PACLITAXEL TREATMENT. WE FURTHER FOUND THAT NFATC2 OCCUPANCY MAY DIRECTLY UPREGULATE THE CHEMOKINE CXCL14 EXPRESSION IN DORSAL HORN, WHICH WAS MEDIATED BY ENHANCED INTERACTION BETWEEN NFATC2 AND P300 AND CONSEQUENTLY INCREASED ACETYLATION OF HISTONE H4 IN CXCL14 PROMOTER REGION. ALSO, KNOCKDOWN OF CXCL14 IN DORSAL HORN SIGNIFICANTLY ATTENUATED MECHANICAL ALLODYNIA INDUCED BY PACLITAXEL. CONCLUSION: THESE RESULTS SUGGESTED THAT ENHANCED INTERACTION BETWEEN P300 AND NFATC2 MEDIATED THE EPIGENETIC UPREGULATION OF CXCL14 IN THE SPINAL DORSAL HORN, WHICH CONTRIBUTED TO THE CHEMOTHERAPEUTIC PACLITAXEL-INDUCED CHRONIC PAIN. 2020 5 1630 38 DNMT3A CONTRIBUTES TO THE DEVELOPMENT AND MAINTENANCE OF BONE CANCER PAIN BY SILENCING KV1.2 EXPRESSION IN SPINAL CORD DORSAL HORN. METASTATIC BONE TUMOR-INDUCED CHANGES IN GENE TRANSCRIPTION AND TRANSLATION IN PAIN-RELATED REGIONS OF THE NERVOUS SYSTEM MAY PARTICIPATE IN THE DEVELOPMENT AND MAINTENANCE OF BONE CANCER PAIN. EPIGENETIC MODIFICATIONS INCLUDING DNA METHYLATION REGULATE GENE TRANSCRIPTION. HERE, WE REPORT THAT INTRATHECAL INJECTION OF DECITABINE, A DNA METHYLTRANSFERASE (DNMT) INHIBITOR, DOSE DEPENDENTLY ATTENUATED THE DEVELOPMENT AND MAINTENANCE OF BONE CANCER PAIN INDUCED BY INJECTING PROSTATE CANCER CELLS INTO THE TIBIA. THE LEVEL OF THE DE NOVO DNMT3A, BUT NOT DNMT3B, TIME DEPENDENTLY INCREASED IN THE IPSILATERAL L4/5 DORSAL HORN (NOT L4/5 DORSAL ROOT GANGLION) AFTER PROSTATE CANCER CELLS INJECTION. BLOCKING THIS INCREASE THROUGH MICROINJECTION OF RECOMBINANT ADENO-ASSOCIATED VIRUS 5 (AAV5) EXPRESSING DNMT3A SHRNA INTO DORSAL HORN RESCUED PROSTATE CANCER CELLS-INDUCED DOWNREGULATION OF DORSAL HORN KV1.2 EXPRESSION AND IMPAIRED PROSTATE CANCER CELLS-INDUCED PAIN HYPERSENSITIVITY. IN TURN, MIMICKING THIS INCREASE THROUGH MICROINJECTION OF AAV5 EXPRESSING FULL-LENGTH DNMT3A INTO DORSAL HORN REDUCED DORSAL HORN KV1.2 EXPRESSION AND PRODUCED PAIN HYPERSENSITIVITY IN THE ABSENCE OF PROSTATE CANCER CELLS INJECTION. ADMINISTRATION OF NEITHER DECITABINE NOR VIRUS AFFECTED LOCOMOTOR FUNCTION AND ACUTE RESPONSES TO MECHANICAL, THERMAL, OR COLD STIMULI. GIVEN THAT DNMT3A MRNA IS CO-EXPRESSED WITH KCNA2 MRNA (ENCODING KV1.2) IN INDIVIDUAL DORSAL HORN NEURONS, OUR FINDINGS SUGGEST THAT INCREASED DORSAL HORN DNMT3A CONTRIBUTES TO BONE CANCER PAIN THROUGH SILENCING DORSAL HORN KV1.2 EXPRESSION. DNMT3A MAY REPRESENT A POTENTIAL NEW TARGET FOR CANCER PAIN MANAGEMENT. 2017 6 4366 35 MIRNA-23A/CXCR4 REGULATES NEUROPATHIC PAIN VIA DIRECTLY TARGETING TXNIP/NLRP3 INFLAMMASOME AXIS. BACKGROUND: CHEMOKINE CXC RECEPTOR 4 (CXCR4) IN SPINAL GLIAL CELLS HAS BEEN IMPLICATED IN NEUROPATHIC PAIN. HOWEVER, THE REGULATORY CASCADES OF CXCR4 IN NEUROPATHIC PAIN REMAIN ELUSIVE. HERE, WE INVESTIGATED THE FUNCTIONAL REGULATORY ROLE OF MIRNAS IN THE PAIN PROCESS AND ITS INTERPLAY WITH CXCR4 AND ITS DOWNSTREAM SIGNALING. METHODS: MIRNAS AND CXCR4 AND ITS DOWNSTREAM SIGNALING MOLECULES WERE MEASURED IN THE SPINAL CORDS OF MICE WITH SCIATIC NERVE INJURY VIA PARTIAL SCIATIC NERVE LIGATION (PSNL). IMMUNOBLOTTING, IMMUNOFLUORESCENCE, IMMUNOPRECIPITATION, AND MAMMAL TWO-HYBRID AND BEHAVIORAL TESTS WERE USED TO EXPLORE THE DOWNSTREAM CXCR4-DEPENDENT SIGNALING PATHWAY. RESULTS: CXCR4 EXPRESSION INCREASED IN SPINAL GLIAL CELLS OF MICE WITH PSNL-INDUCED NEUROPATHIC PAIN. BLOCKING CXCR4 ALLEVIATED THE PAIN BEHAVIOR; CONTRARILY, OVEREXPRESSING CXCR4 INDUCED PAIN HYPERSENSITIVITY. MICRORNA-23A-3P (MIR-23A) DIRECTLY BOUNDS TO 3' UTR OF CXCR4 MRNA. PSNL-INDUCED NEUROPATHIC PAIN SIGNIFICANTLY REDUCED MRNA EXPRESSION OF MIR-23A. OVEREXPRESSION OF MIR-23A BY INTRATHECAL INJECTION OF MIR-23A MIMICS OR LENTIVIRUS REDUCED SPINAL CXCR4 AND PREVENTED PSNL-INDUCED NEUROPATHIC PAIN. IN CONTRAST, KNOCKDOWN OF MIR-23A BY INTRATHECAL INJECTION OF MIR-23A INHIBITOR OR LENTIVIRUS INDUCED PAIN-LIKE BEHAVIOR, WHICH WAS REDUCED BY CXCR4 INHIBITION. ADDITIONALLY, MIR-23A KNOCKDOWN OR CXCR4 OVEREXPRESSION IN NAIVE MICE COULD INCREASE THE THIOREDOXIN-INTERACTING PROTEIN (TXNIP), WHICH WAS ASSOCIATED WITH INDUCTION OF NOD-LIKE RECEPTOR PROTEIN 3 (NLRP3) INFLAMMASOME. INDEED, CXCR4 AND TXNIP WERE CO-EXPRESSED. THE MAMMAL TWO-HYBRID ASSAY REVEALED THE DIRECT INTERACTION BETWEEN CXCR4 AND TXNIP, WHICH WAS INCREASED IN THE SPINAL CORD OF PSNL MICE. IN PARTICULAR, INHIBITION OF TXNIP REVERSED PAIN BEHAVIOR ELICITED BY PSNL, MIR-23A KNOCKDOWN, OR CXCR4 OVEREXPRESSION. MOREOVER, MIR-23A OVEREXPRESSION OR CXCR4 KNOCKDOWN INHIBITED THE INCREASE OF TXNIP AND NLRP3 INFLAMMASOME IN PSNL MICE. CONCLUSIONS: MIR-23A, BY DIRECTLY TARGETING CXCR4, REGULATES NEUROPATHIC PAIN VIA TXNIP/NLRP3 INFLAMMASOME AXIS IN SPINAL GLIAL CELLS. EPIGENETIC INTERVENTIONS AGAINST MIR-23A, CXCR4, OR TXNIP MAY POTENTIALLY SERVE AS NOVEL THERAPEUTIC AVENUES IN TREATING PERIPHERAL NERVE INJURY-INDUCED NOCICEPTIVE HYPERSENSITIVITY. 2018 7 2885 28 G9A PARTICIPATES IN NERVE INJURY-INDUCED KCNA2 DOWNREGULATION IN PRIMARY SENSORY NEURONS. NERVE INJURY-INDUCED DOWNREGULATION OF VOLTAGE-GATED POTASSIUM CHANNEL SUBUNIT KCNA2 IN THE DORSAL ROOT GANGLION (DRG) IS CRITICAL FOR DRG NEURONAL EXCITABILITY AND NEUROPATHIC PAIN GENESIS. HOWEVER, HOW NERVE INJURY CAUSES THIS DOWNREGULATION IS STILL ELUSIVE. EUCHROMATIC HISTONE-LYSINE N-METHYLTRANSFERASE 2, ALSO KNOWN AS G9A, METHYLATES HISTONE H3 ON LYSINE RESIDUE 9 TO PREDOMINANTLY PRODUCE A DYNAMIC HISTONE DIMETHYLATION, RESULTING IN CONDENSED CHROMATIN AND GENE TRANSCRIPTIONAL REPRESSION. WE SHOWED HERE THAT BLOCKING NERVE INJURY-INDUCED INCREASE IN G9A RESCUED KCNA2 MRNA AND PROTEIN EXPRESSION IN THE AXOTOMIZED DRG AND ATTENUATED THE DEVELOPMENT OF NERVE INJURY-INDUCED PAIN HYPERSENSITIVITY. MIMICKING THIS INCREASE DECREASED KCNA2 MRNA AND PROTEIN EXPRESSION, REDUCED KV CURRENT, AND INCREASED EXCITABILITY IN THE DRG NEURONS AND LED TO SPINAL CORD CENTRAL SENSITIZATION AND NEUROPATHIC PAIN-LIKE SYMPTOMS. G9A MRNA IS CO-LOCALIZED WITH KCNA2 MRNA IN THE DRG NEURONS. THESE FINDINGS INDICATE THAT G9A CONTRIBUTES TO NEUROPATHIC PAIN DEVELOPMENT THROUGH EPIGENETIC SILENCING OF KCNA2 IN THE AXOTOMIZED DRG. 2016 8 5780 40 SPINAL RNF20-MEDIATED HISTONE H2B MONOUBIQUITYLATION REGULATES MGLUR5 TRANSCRIPTION FOR NEUROPATHIC ALLODYNIA. TO DATE, HISTONE H2B MONOUBIQUITINATION (H2BUB), A MARK ASSOCIATED WITH TRANSCRIPTIONAL ELONGATION AND ONGOING TRANSCRIPTION, HAS NOT BEEN LINKED TO THE DEVELOPMENT OR MAINTENANCE OF NEUROPATHIC PAIN STATES. HERE, USING MALE SPRAGUE DAWLEY RATS, WE DEMONSTRATED SPINAL NERVE LIGATION (SNL) INDUCED BEHAVIORAL ALLODYNIA AND PROVOKED RING FINGER PROTEIN 20 (RNF20)-DEPENDENT H2BUB IN DORSAL HORN. MOREOVER, SNL PROVOKED RNF20-MEDIATED H2BUB PHOSPHORYLATED RNA POLYMERASE II (RNAPII) IN THE PROMOTER FRAGMENTS OF MGLUR5, THEREBY ENHANCING MGLUR5 TRANSCRIPTION/EXPRESSION IN THE DORSAL HORN. CONVERSELY, FOCAL KNOCKDOWN OF SPINAL RNF20 EXPRESSION REVERSED NOT ONLY SNL-INDUCED ALLODYNIA BUT ALSO RNF20/H2BUB/RNAPII PHOSPHORYLATION-ASSOCIATED SPINAL MGLUR5 TRANSCRIPTION/EXPRESSION. NOTABLY, TNF-ALPHA INJECTION INTO NAIVE RATS AND SPECIFIC NEUTRALIZING ANTIBODY INJECTION INTO SNL-INDUCED ALLODYNIA RATS REVEALED THAT TNF-ALPHA-ASSOCIATED ALLODYNIA INVOLVES THE RNF20/H2BUB/RNAPII TRANSCRIPTIONAL AXIS TO UPREGULATE MGLUR5 EXPRESSION IN THE DORSAL HORN. COLLECTIVELY, OUR FINDINGS INDICATED TNF-ALPHA INDUCES RNF20-DRIVED H2B MONOUBIQUITINATION, WHICH FACILITATES PHOSPHORYLATED RNAPII-DEPENDENT MGLUR5 TRANSCRIPTION IN THE DORSAL HORN FOR THE DEVELOPMENT OF NEUROPATHIC ALLODYNIA.SIGNIFICANCE STATEMENT HISTONE H2B MONOUBIQUITINATION (H2BUB), AN EPIGENETIC POST-TRANSLATIONAL MODIFICATION, POSITIVELY CORRELATED WITH GENE EXPRESSION. HERE, TNF-ALPHA PARTICIPATED IN NEUROPATHIC PAIN DEVELOPMENT BY ENHANCING RNF20-MEDIATED H2BUB, WHICH FACILITATES PHOSPHORYLATED RNAPII-DEPENDENT MGLUR5 TRANSCRIPTION IN DORSAL HORN. OUR FINDING POTENTIALLY IDENTIFIED NEUROPATHIC ALLODYNIA PATHOPHYSIOLOGICAL PROCESSES UNDERPINNING ABNORMAL NOCICEPTION PROCESSING AND OPENS A NEW AVENUE FOR THE DEVELOPMENT OF NOVEL ANALGESICS. 2018 9 2407 32 EPIGENETIC RESTORATION OF VOLTAGE-GATED POTASSIUM CHANNEL KV1.2 ALLEVIATES NERVE INJURY-INDUCED NEUROPATHIC PAIN. VOLTAGE-GATED POTASSIUM CHANNELS (KV) ARE IMPORTANT REGULATORS OF NEURONAL EXCITABILITY FOR ITS ROLE OF REGULATING RESTING MEMBRANE POTENTIAL AND REPOLARIZATION. RECENT STUDIES SHOW THAT KV CHANNELS PARTICIPATE IN NEUROPATHIC PAIN, BUT THE DETAILED UNDERLYING MECHANISMS ARE FAR FROM BEING CLEAR. IN THIS STUDY, WE USED SIRNA, MIR-137 AGOMIR, AND ANTAGOMIR TO REGULATE THE EXPRESSION OF KV1.2 IN SPINAL CORD AND DORSAL ROOT GANGLIA (DRG) OF NAIVE AND CHRONIC CONSTRICTION INJURY (CCI) RATS. KV CURRENTS AND NEURON EXCITABILITY IN DRG NEURONS WERE EXAMINED BY PATCH-CLAMP WHOLE-CELL RECORDING TO VERIFY THE CHANGE IN KV1.2 FUNCTION. THE RESULTS SHOWED THAT KV1.2 WAS DOWN-REGULATED IN DRG AND SPINAL DORSAL HORN (SDH) BY CCI. KNOCKDOWN OF KV1.2 BY INTRATHECALLY INJECTING KCNA2 SIRNA INDUCED SIGNIFICANT MECHANICAL AND THERMAL HYPERSENSITIVITY IN NAIVE RATS. CONCOMITANT WITH THE DOWN-REGULATION OF KV1.2 WAS AN INCREASE IN THE EXPRESSION OF THE MIR-137. THE TARGETING AND REGULATING OF MIR-137 ON KCNA2 WAS VERIFIED BY DUAL-LUCIFERASE REPORTER SYSTEM AND INTRATHECAL INJECTING MIR-137 AGOMIR. FURTHERMORE, RESCUING THE EXPRESSION OF KV1.2 IN CCI RATS, ACHIEVED THROUGH INHIBITING MIR-137, RESTORED THE ABNORMAL KV CURRENTS AND EXCITABILITY IN DRG NEURONS, AND ALLEVIATED MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA. THESE RESULTS INDICATE THAT THE MIR-137-MEDIATED KV1.2 IMPAIRMENT IS A CRUCIAL ETIOPATHOGENESIS FOR THE NERVE INJURY-INDUCED NEUROPATHIC PAIN AND CAN BE A NOVEL POTENTIAL THERAPEUTIC TARGET FOR NEUROPATHIC PAIN MANAGEMENT. 2021 10 2751 32 EXPRESSION OF ACETYL-HISTONE H3 AND ACETYL-HISTONE H4 IN DORSAL ROOT GANGLION AND SPINAL DORSAL HORN IN RAT CHRONIC PAIN MODELS. AIMS: HISTONE ACETYLATION AND DEACETYLATION ARE TWO HISTONE POSTTRANSLATIONAL MODIFICATIONS THAT ARE USUALLY CONTROLLED BY HISTONE ACETYLTRANSFERASES (HATS) AND HISTONE DEACETYLASES (HDACS). ALTHOUGH HATS OR HDACS INHIBITORS COULD RELIEVE PAIN HYPERSENSITIVITIES IN CHRONIC PAIN ANIMAL MODELS, IT IS NOT CLEAR ON THE EXPRESSION OF GLOBAL HISTONE ACETYLATION IN THE DORSAL ROOT GANGLION (DRG) OR SPINAL DORSAL HORN IN CHRONIC PAIN CONDITIONS. MAIN METHODS: A SPINAL NERVE LIGATION (SNL)-INDUCED NEUROPATHIC PAIN MODEL AND A COMPLETE FREUND'S ADJUVANT (CFA)-INDUCED INFLAMMATORY PAIN MODEL IN RATS WERE USED TO EXAMINE THE EXPRESSION OF TOTAL ACETYL-HISTONE H3 (ACH3) AND TOTAL ACETYL-HISTONE H4 (ACH4) BY IMMUNOFLUORESCENCE OR WESTERN BLOT. KEY FINDINGS: ACH3 AND ACH4 NOT ONLY LOCALIZED IN NEURONAL NUCLEI, BUT ALSO IN NUCLEI OF GLIAL CELLS IN THE DRG. UNILATERAL SNL INDUCED THE INCREASE OF ACH3 AND ACH4 EXPRESSION IN THE INJURED LUMBAR 5 (L5) DRG, BUT NOT IN THE UNINJURED L5 DRG OR THE SPINAL DORSAL HORN, WHILE UNILATERAL INTRAPLANTAR INJECTION OF CFA INCREASED ACH3 AND ACH4 EXPRESSION IN THE IPSILATERAL L4/5 SPINAL DORSAL HORN, BUT NOT IN THE L4/5 DRG. SIGNIFICANCE: THESE RESULTS PROVIDE MORPHOLOGICAL EVIDENCE FOR GLOBAL HISTONE ACETYLATION EXPRESSION IN THE DRG AND SPINAL CORD AND INDICATE THE DIFFERENTIAL EXPRESSION IN THE DRG AND SPINAL DORSAL HORN IN DIFFERENT CHRONIC PAIN MODELS. MORE PRECISE EPIGENETIC MECHANISMS OF HISTONE ACETYLATION ON THE TARGET GENES NEED TO BE REVEALED. 2018 11 5574 28 ROLE OF MICRORNA-143 IN NERVE INJURY-INDUCED UPREGULATION OF DNMT3A EXPRESSION IN PRIMARY SENSORY NEURONS. PERIPHERAL NERVE INJURY INCREASED THE EXPRESSION OF THE DNA METHYLTRANSFERASE 3A (DNMT3A) MRNA AND ITS ENCODING DNMT3A PROTEIN IN INJURED DORSAL ROOT GANGLIA (DRG). THIS INCREASE IS CONSIDERED AS AN ENDOGENOUS INSTIGATOR IN NEUROPATHIC PAIN GENESIS THROUGH EPIGENETIC SILENCING OF PAIN-ASSOCIATED GENES (SUCH AS OPRM1) IN INJURED DRG. HOWEVER, HOW DRG DNMT3A IS INCREASED FOLLOWING PERIPHERAL NERVE INJURY IS STILL ELUSIVE. WE REPORTED HERE THAT PERIPHERAL NERVE INJURY CAUSED BY THE FIFTH SPINAL NERVE LIGATION (SNL) DOWNREGULATED MICRORNA (MIR)-143 EXPRESSION IN INJURED DRG. THIS DOWNREGULATION WAS REQUIRED FOR SNL-INDUCED DRG DNMT3A INCREASE AS RESCUING MIR-143 DOWNREGULATION THROUGH MICROINJECTION OF MIR-143 MIMICS INTO INJURED DRG BLOCKED THE SNL-INDUCED INCREASE IN DNMT3A AND RESTORED THE SNL-INDUCED DECREASES IN OPRM1 MRNA AND ITS ENCODING MU OPIOID RECEPTOR (MOR) IN INJURED DRG, IMPAIRED SPINAL CORD CENTRAL SENSITIZATION AND NEUROPATHIC PAIN, AND IMPROVED MORPHINE ANALGESIC EFFECTS FOLLOWING SNL. MIMICKING SNL-INDUCED DRG MIR-143 DOWNREGULATION THROUGH DRG MICROINJECTION OF MIR143 INHIBITORS IN NAIVE RATS INCREASED THE EXPRESSION OF DNMT3A AND REDUCED THE EXPRESSION OF OPRM1 MRNA AND MOR IN INJECTED DRG AND PRODUCED NEUROPATHIC PAIN-LIKE SYMPTOMS. THESE FINDINGS SUGGEST THAT MIR-143 IS A NEGATIVE REGULATOR IN DNMT3A EXPRESSION IN THE DRG UNDER NEUROPATHIC PAIN CONDITIONS AND MAY BE A POTENTIAL TARGET FOR THERAPEUTIC MANAGEMENT OF NEUROPATHIC PAIN. 2017 12 4698 45 NFATC2-DEPENDENT EPIGENETIC DOWNREGULATION OF THE TSC2/BECLIN-1 PATHWAY IS INVOLVED IN NEUROPATHIC PAIN INDUCED BY OXALIPLATIN. NEUROPATHIC PAIN IS A COMMON DOSE-LIMITING SIDE EFFECT OF OXALIPLATIN, WHICH HAMPERS THE EFFECTIVE TREATMENT OF TUMORS. HERE, WE FOUND THAT UPREGULATION OF TRANSCRIPTION FACTOR NFATC2 DECREASED THE EXPRESSION OF BECLIN-1, A CRITICAL MOLECULE IN AUTOPHAGY, IN THE SPINAL DORSAL HORN, AND CONTRIBUTED TO NEUROPATHIC PAIN FOLLOWING OXALIPLATIN TREATMENT. MEANWHILE, MANIPULATING AUTOPHAGY LEVELS BY INTRATHECAL INJECTION OF RAPAMYCIN (RAPA) OR 3-METHYLADENINE (3-MA) DIFFERENTIALLY ALTERED MECHANICAL ALLODYNIA IN OXALIPLATIN-TREATED OR NAIVE RATS. UTILIZING CHROMATIN IMMUNOPRECIPITATION-SEQUENCING (CHIP-SEQ) ASSAY COMBINED WITH BIOINFORMATICS ANALYSIS, WE FOUND THAT NFATC2 NEGATIVELY REGULATED THE TRANSCRIPTION OF TUBEROUS SCLEROSIS COMPLEX PROTEIN 2 (TSC2), WHICH CONTRIBUTED TO THE OXALIPLATIN-INDUCED BECLIN-1 DOWNREGULATION. FURTHER ASSAYS REVEALED THAT NFATC2 REGULATED HISTONE H4 ACETYLATION AND METHYLATION IN THE TSC2 PROMOTER SITE 1 IN RATS' DORSAL HORNS WITH OXALIPLATIN TREATMENT. THESE RESULTS SUGGESTED THAT NFATC2 MEDIATED THE EPIGENETIC DOWNREGULATION OF THE TSC2/BECLIN-1 AUTOPHAGY PATHWAY AND CONTRIBUTED TO OXALIPLATIN-INDUCED MECHANICAL ALLODYNIA, WHICH PROVIDED A NEW THERAPEUTIC INSIGHT FOR CHEMOTHERAPY-INDUCED NEUROPATHIC PAIN. 2023 13 2898 57 GATA3-DEPENDENT EPIGENETIC UPREGULATION OF CCL21 IS INVOLVED IN THE DEVELOPMENT OF NEUROPATHIC PAIN INDUCED BY BORTEZOMIB. THE INCIDENCE OF BORTEZOMIB-INDUCED NEUROPATHIC PAIN HAMPERS THE PROGRESS OF THERAPY FOR NEOPLASIA AND ALSO NEGATIVELY AFFECTS THE QUALITY OF LIFE OF PATIENTS. HOWEVER, THE MOLECULAR MECHANISM UNDERLYING BORTEZOMIB-INDUCED NEUROPATHIC PAIN REMAINS UNKNOWN. IN THIS STUDY, WE FOUND THAT THE APPLICATION OF BORTEZOMIB SIGNIFICANTLY INCREASED THE EXPRESSION OF GATA-BINDING PROTEIN 3 (GATA3) IN THE SPINAL DORSAL HORN, AND INTRATHECAL ADMINISTRATION OF GATA3 SIRNA ATTENUATED MECHANICAL ALLODYNIA. FURTHERMORE, CHROMATIN IMMUNOPRECIPITATION SEQUENCING SHOWED THAT BORTEZOMIB TREATMENT INDUCED THE REDISTRIBUTION OF GATA3 TO TRANSCRIPTIONAL RELEVANT REGIONS. NOTABLY, COMBINED WITH THE RESULTS OF MRNA MICROARRAY, WE FOUND THAT C-C MOTIF CHEMOKINE LIGAND 21 (CCL21) HAD AN INCREASED GATA3 BINDING AND UPREGULATED MRNA EXPRESSION IN THE DORSAL HORN AFTER BORTEZOMIB TREATMENT. NEXT, WE FOUND THAT BORTEZOMIB TREATMENT INDUCED CCL21 UPREGULATION IN THE SPINAL NEURONS, WHICH WAS SIGNIFICANTLY REDUCED UPON GATA3 SILENCING. BLOCKADE OF CCL21 USING THE NEUTRALIZING ANTIBODY OR SPECIAL SIRNA AMELIORATED MECHANICAL ALLODYNIA INDUCED BY BORTEZOMIB. IN ADDITION, BORTEZOMIB TREATMENT INCREASED THE ACETYLATION OF HISTONE H3 AND THE INTERACTION BETWEEN GATA3 AND CREB-BINDING PROTEIN. GATA3 SIRNA SUPPRESSED THE CCL21 UPREGULATION BY DECREASING THE ACETYLATION OF HISTONE H3. TOGETHER, THESE RESULTS SUGGESTED THAT ACTIVATION OF GATA3 MEDIATED THE EPIGENETIC UPREGULATION OF CCL21 IN DORSAL HORN NEURONS, WHICH CONTRIBUTED TO THE BORTEZOMIB-INDUCED NEUROPATHIC PAIN. 2019 14 1654 32 DORSAL ROOT GANGLIA COACTIVATOR-ASSOCIATED ARGININE METHYLTRANSFERASE 1 CONTRIBUTES TO PERIPHERAL NERVE INJURY-INDUCED PAIN HYPERSENSITIVITIES. NEUROPATHIC PAIN IS ASSOCIATED WITH GENE EXPRESSION CHANGES WITHIN THE DORSAL ROOT GANGLION (DRG) AFTER PERIPHERAL NERVE INJURY, WHICH INVOLVES EPIGENETIC MECHANISMS. COACTIVATOR-ASSOCIATED ARGININE METHYLTRANSFERASE 1 (CARM1), AN EPIGENETIC ACTIVATOR, REGULATES GENE TRANSCRIPTIONAL ACTIVITY BY PROTEIN POSTTRANSLATIONAL MODIFICATIONS. HOWEVER, WHETHER CARM1 PLAYS AN ESSENTIAL ROLE IN THE DEVELOPMENT AND MAINTENANCE OF NEUROPATHIC PAIN IS UNKNOWN. WE REPORT HERE THAT PERIPHERAL NERVE INJURY INDUCED THE UPREGULATION OF THE MRNA AND PROTEIN EXPRESSION OF CARM1 IN THE INJURED DRG, AND BLOCKING ITS EXPRESSION THROUGH SMALL INTERFERING RNA (SIRNA) IN THE INJURED DRG ATTENUATED THE DEVELOPMENT AND MAINTENANCE OF NEUROPATHIC PAIN. FURTHERMORE, PHARMACOLOGICAL INHIBITION OF CARM1 MITIGATED PERIPHERAL NERVE INJURY-INDUCED MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA. GIVEN THAT CARM1 INHIBITION OR KNOCKDOWN ATTENUATED THE INDUCTION AND MAINTENANCE OF NEUROPATHIC PAIN AFTER PERIPHERAL NERVE INJURY, OUR FINDINGS SUGGEST THAT CARM1 MAY SERVE AS A PROMISING THERAPEUTIC TARGET FOR NEUROPATHIC PAIN TREATMENT IN CLINICAL APPLICATIONS. 2018 15 742 41 CANNABINOID CB2 RECEPTORS ARE UPREGULATED VIA BIVALENT HISTONE MODIFICATIONS AND CONTROL PRIMARY AFFERENT INPUT TO THE SPINAL CORD IN NEUROPATHIC PAIN. TYPE-2 CANNABINOID RECEPTORS (CB2, ENCODED BY THE CNR2 GENE) ARE MAINLY EXPRESSED IN IMMUNE CELLS, AND CB2 AGONISTS NORMALLY HAVE NO ANALGESIC EFFECT. HOWEVER, NERVE INJURY UPREGULATES CB2 IN THE DORSAL ROOT GANGLION (DRG), FOLLOWING WHICH CB2 STIMULATION REDUCES NEUROPATHIC PAIN. IT IS UNCLEAR HOW NERVE INJURY INCREASES CB2 EXPRESSION OR HOW CB2 ACTIVITY IS TRANSFORMED IN NEUROPATHIC PAIN. IN THIS STUDY, IMMUNOBLOTTING SHOWED THAT SPINAL NERVE LIGATION (SNL) INDUCED A DELAYED AND SUSTAINED INCREASE IN CB2 EXPRESSION IN THE DRG AND DORSAL SPINAL CORD SYNAPTOSOMES. RNASCOPE IN SITU HYBRIDIZATION ALSO SHOWED THAT SNL SUBSTANTIALLY INCREASED CB2 MRNA LEVELS, MOSTLY IN MEDIUM AND LARGE DRG NEURONS. FURTHERMORE, WE FOUND THAT THE SPECIFIC CB2 AGONIST JWH-133 SIGNIFICANTLY INHIBITS THE AMPLITUDE OF DORSAL ROOT-EVOKED GLUTAMATERGIC EXCITATORY POSTSYNAPTIC CURRENTS IN SPINAL DORSAL HORN NEURONS IN SNL RATS, BUT NOT IN SHAM CONTROL RATS; INTRATHECAL INJECTION OF JWH-133 REVERSED PAIN HYPERSENSITIVITY IN SNL RATS, BUT HAD NO EFFECT IN SHAM CONTROL RATS. IN ADDITION, CHROMATIN IMMUNOPRECIPITATION-QPCR ANALYSIS SHOWED THAT SNL INCREASED ENRICHMENT OF TWO ACTIVATING HISTONE MARKS (H3K4ME3 AND H3K9AC) AND DIMINISHED OCCUPANCY OF TWO REPRESSIVE HISTONE MARKS (H3K9ME2 AND H3K27ME3) AT THE CNR2 PROMOTER IN THE DRG. IN CONTRAST, SNL HAD NO EFFECT ON DNA METHYLATION LEVELS AROUND THE CNR2 PROMOTER. OUR FINDINGS SUGGEST THAT PERIPHERAL NERVE INJURY PROMOTES CB2 EXPRESSION IN PRIMARY SENSORY NEURONS VIA EPIGENETIC BIVALENT HISTONE MODIFICATIONS AND THAT CB2 ACTIVATION REDUCES NEUROPATHIC PAIN BY ATTENUATING NOCICEPTIVE TRANSMISSION FROM PRIMARY AFFERENT NERVES TO THE SPINAL CORD. 2022 16 1166 26 CONTRIBUTION OF DNMT1 TO NEUROPATHIC PAIN GENESIS PARTIALLY THROUGH EPIGENETICALLY REPRESSING KCNA2 IN PRIMARY AFFERENT NEURONS. EXPRESSIONAL CHANGES OF PAIN-ASSOCIATED GENES IN PRIMARY SENSORY NEURONS OF DRG ARE CRITICAL FOR NEUROPATHIC PAIN GENESIS. DNA METHYLTRANSFERASE (DNMT)-TRIGGERED DNA METHYLATION SILENCES GENE EXPRESSION. WE SHOW HERE THAT DNMT1, A CANONICAL MAINTENANCE METHYLTRANSFERASE, ACTS AS THE DE NOVO DNMT AND IS REQUIRED FOR NEUROPATHIC PAIN GENESIS LIKELY THROUGH REPRESSING AT LEAST DRG KCNA2 GENE EXPRESSION IN MALE MICE. PERIPHERAL NERVE INJURY UPREGULATED DNMT1 EXPRESSION IN THE INJURED DRG THROUGH THE TRANSCRIPTION FACTOR CAMP RESPONSE ELEMENT BINDING PROTEIN-TRIGGERED TRANSCRIPTIONAL ACTIVATION OF DNMT1 GENE. BLOCKING THIS UPREGULATION PREVENTED NERVE INJURY-INDUCED DNA METHYLATION WITHIN THE PROMOTER AND 5'-UNTRANSLATED REGION OF KCNA2 GENE, RESCUED KCNA2 EXPRESSION AND TOTAL KV CURRENT, ATTENUATED HYPEREXCITABILITY IN THE INJURED DRG NEURONS, AND ALLEVIATED NERVE INJURY-INDUCED PAIN HYPERSENSITIVITIES. GIVEN THAT KCNA2 IS A KEY PLAYER IN NEUROPATHIC PAIN, OUR FINDINGS SUGGEST THAT DRG DNMT1 MAY BE A POTENTIAL TARGET FOR NEUROPATHIC PAIN MANAGEMENT.SIGNIFICANCE STATEMENT IN THE PRESENT STUDY, WE REPORTED THAT DNMT1, A CANONICAL DNA MAINTENANCE METHYLTRANSFERASE, IS UPREGULATED VIA THE ACTIVATION OF THE TRANSCRIPTION FACTOR CREB IN THE INJURED DRG AFTER PERIPHERAL NERVE INJURY. THIS UPREGULATION WAS RESPONSIBLE FOR NERVE INJURY-INDUCED DE NOVO DNA METHYLATION WITHIN THE PROMOTER AND 5'-UNTRANSLATED REGION OF THE KCNA2 GENE, REDUCTIONS IN KCNA2 EXPRESSION AND KV CURRENT AND INCREASES IN NEURONAL EXCITABILITY IN THE INJURED DRG. SINCE PHARMACOLOGICAL INHIBITION OR GENETIC KNOCKDOWN OF DRG DNMT1 ALLEVIATED NERVE INJURY-INDUCED PAIN HYPERSENSITIVITIES, DRG DNMT1 CONTRIBUTES TO NEUROPATHIC PAIN GENESIS PARTIALLY THROUGH REPRESSION OF DRG KCNA2 GENE EXPRESSION. 2019 17 2475 51 EPIGENETIC UP-REGULATION OF ADAMTS4 IN SYMPATHETIC GANGLIA IS INVOLVED IN THE MAINTENANCE OF NEUROPATHIC PAIN FOLLOWING NERVE INJURY. SYMPATHETIC AXONAL SPROUTING INTO DORSAL ROOT GANGLIA IS A MAJOR PHENOMENON IMPLICATED IN NEUROPATHIC PAIN, AND SYMPATHETIC GANGLIA BLOCKAGE MAY RELIEVE SOME INTRACTABLE CHRONIC PAIN IN ANIMAL PAIN MODELS AND CLINICAL CONDITIONS. THESE SUGGEST THAT SYMPATHETIC GANGLIA PARTICIPATED IN THE MAINTENANCE OF CHRONIC PAIN. HOWEVER, THE MOLECULAR MECHANISM UNDERLYING SYMPATHETIC GANGLIA-MEDIATED CHRONIC PAIN IS NOT CLEAR. HERE, WE FOUND THAT SPARED NERVE INJURY TREATMENT UPREGULATED THE EXPRESSION OF ADAMTS4 AND AP-2ALPHA PROTEIN AND MRNA IN THE NORADRENERGIC NEURONS OF SYMPATHETIC GANGLIA DURING NEUROPATHIC PAIN MAINTENANCE. KNOCKDOWN THE ADAMTS4 OR AP-2ALPHA BY INJECTING SPECIFIC RETRO SCAAV-TH (TYROSINE HYDROXYLASE)-SHRNA AMELIORATED THE MECHANICAL ALLODYNIA INDUCED BY SPARED NERVE INJURY ON DAY 21 AND 28. FURTHERMORE, CHROMATIN IMMUNOPRECIPITATION AND COIMMUNOPRECIPITATION ASSAYS FOUND THAT SPARED NERVE INJURY INCREASED THE RECRUITMENT OF AP-2ALPHA TO THE ADAMTS4 GENE PROMOTER, THE INTERACTION BETWEEN AP-2ALPHA AND HISTONE ACETYLTRANSFERASE P300 AND THE HISTONE H4 ACETYLATION ON DAY 28. FINALLY, KNOCKDOWN THE AP-2ALPHA REDUCED THE ACETYLATION OF H4 ON THE PROMOTER REGION OF ADAMTS4 GENE AND SUPPRESSED THE INCREASE OF ADAMTS4 EXPRESSION INDUCED BY SPARED NERVE INJURY. TOGETHER, THESE RESULTS SUGGESTED THAT THE ENHANCED INTERACTION BETWEEN AP-2ALPHA AND P300 MEDIATED THE EPIGENETIC UPREGULATION OF ADAMTS4 IN SYMPATHETIC GANGLIA NORADRENERGIC NEURONS, WHICH CONTRIBUTED TO THE MAINTENANCE OF SPARED NERVE INJURY INDUCED NEUROPATHIC PAIN. 2023 18 6424 34 THE TRANSCRIPTION FACTOR C/EBPBETA IN THE DORSAL ROOT GANGLION CONTRIBUTES TO PERIPHERAL NERVE TRAUMA-INDUCED NOCICEPTIVE HYPERSENSITIVITY. CHANGES IN GENE TRANSCRIPTION IN THE DORSAL ROOT GANGLION (DRG) AFTER NERVE TRAUMA CONTRIBUTE TO THE GENESIS OF NEUROPATHIC PAIN. WE REPORT THAT PERIPHERAL NERVE TRAUMA CAUSED BY CHRONIC CONSTRICTION INJURY (CCI) INCREASED THE ABUNDANCE OF THE TRANSCRIPTION FACTOR C/EBPBETA (CCAAT/ENHANCER BINDING PROTEIN BETA) IN THE DRG. BLOCKING THIS INCREASE MITIGATED THE DEVELOPMENT AND MAINTENANCE OF CCI-INDUCED MECHANICAL, THERMAL, AND COLD PAIN HYPERSENSITIVITIES WITHOUT AFFECTING BASAL RESPONSES TO ACUTE PAIN AND LOCOMOTOR ACTIVITY. CONVERSELY, MIMICKING THIS INCREASE PRODUCED HYPERSENSITIVITY TO MECHANICAL, THERMAL, OR COLD PAIN. IN THE IPSILATERAL DRG, C/EBPBETA PROMOTED A DECREASE IN THE ABUNDANCE OF THE VOLTAGE-GATED POTASSIUM CHANNEL SUBUNIT KV1.2 AND MU OPIOID RECEPTOR (MOR) AT THE MRNA AND PROTEIN LEVELS, WHICH WOULD BE PREDICTED TO INCREASE EXCITABILITY IN THE IPSILATERAL DRG NEURONS AND REDUCE THE EFFICACY OF MORPHINE ANALGESIA. THESE EFFECTS REQUIRED C/EPBBETA-MEDIATED TRANSCRIPTIONAL ACTIVATION OF EHMT2 (EUCHROMATIC HISTONE-LYSINE N-METHYLTRANSFERASE 2), WHICH ENCODES G9A, AN EPIGENETIC SILENCER OF THE GENES ENCODING KV1.2 AND MOR. BLOCKING THE INCREASE IN C/EBPBETA IN THE DRG IMPROVED MORPHINE ANALGESIA AFTER CCI. THESE RESULTS SUGGEST THAT C/EBPBETA IS AN ENDOGENOUS INITIATOR OF NEUROPATHIC PAIN AND COULD BE A POTENTIAL TARGET FOR THE PREVENTION AND TREATMENT OF THIS DISORDER. 2017 19 5266 48 PROMOTED INTERACTION OF C/EBPALPHA WITH DEMETHYLATED CXCR3 GENE PROMOTER CONTRIBUTES TO NEUROPATHIC PAIN IN MICE. DNA METHYLATION HAS BEEN IMPLICATED IN THE PATHOGENESIS OF CHRONIC PAIN. HOWEVER, THE SPECIFIC GENES REGULATED BY DNA METHYLATION UNDER NEUROPATHIC PAIN CONDITION REMAIN LARGELY UNKNOWN. HERE WE INVESTIGATED HOW CHEMOKINE RECEPTOR CXCR3 IS REGULATED BY DNA METHYLATION AND HOW IT CONTRIBUTES TO NEUROPATHIC PAIN INDUCED BY SPINAL NERVE LIGATION (SNL) IN MICE. SNL INCREASED CXCR3 MRNA AND PROTEIN EXPRESSION IN THE NEURONS OF THE SPINAL CORD. MEANWHILE, THE CPG (5'-CYTOSINE-PHOSPHATE-GUANINE-3') ISLAND IN THE CXCR3 GENE PROMOTER REGION WAS DEMETHYLATED, AND THE EXPRESSION OF DNA METHYLTRANSFERASE 3B (DNMT3B) WAS DECREASED. SNL ALSO INCREASED THE BINDING OF CCAAT (CYTIDINE-CYTIDINE-ADENOSINE-ADENOSINE-THYMIDINE)/ENHANCER BINDING PROTEIN ALPHA (C/EBPALPHA) WITH CXCR3 PROMOTER AND DECREASED THE BINDING OF DNMT3B WITH CXCR3 PROMOTER IN THE SPINAL CORD. C/EBPALPHA EXPRESSION WAS INCREASED IN SPINAL NEURONS AFTER SNL, AND INHIBITION OF C/EBPALPHA BY INTRATHECAL SMALL INTERFERING RNA ATTENUATED SNL-INDUCED PAIN HYPERSENSITIVITY AND REDUCED CXCR3 EXPRESSION. FURTHERMORE, SNL-INDUCED MECHANICAL ALLODYNIA AND HEAT HYPERALGESIA WERE MARKEDLY REDUCED IN CXCR3(-/-) MICE. SPINAL INHIBITION OF CXCR3 BY SHRNA OR CXCR3 ANTAGONIST ALSO ATTENUATED ESTABLISHED NEUROPATHIC PAIN. MOREOVER, CXCL10, THE LIGAND OF CXCR3, WAS INCREASED IN SPINAL NEURONS AND ASTROCYTES AFTER SNL. SUPERFUSING SPINAL CORD SLICES WITH CXCL10 ENHANCED SPONTANEOUS EPSCS AND POTENTIATED NMDA-INDUCED AND AMPA-INDUCED CURRENTS OF LAMINA II NEURONS. FINALLY, INTRATHECAL INJECTION OF CXCL10 INDUCED CXCR3-DEPENDENT PAIN HYPERSENSITIVITY IN NAIVE MICE. COLLECTIVELY, OUR RESULTS DEMONSTRATED THAT CXCR3, INCREASED BY DNA DEMETHYLATION AND THE ENHANCED INTERACTION WITH C/EBPALPHA, CAN BE ACTIVATED BY CXCL10 TO FACILITATE EXCITATORY SYNAPTIC TRANSMISSION AND CONTRIBUTE TO THE MAINTENANCE OF NEUROPATHIC PAIN. SIGNIFICANCE STATEMENT: PERIPHERAL NERVE INJURY INDUCES CHANGES OF GENE EXPRESSION IN THE SPINAL CORD THAT MAY CONTRIBUTE TO THE PATHOGENESIS OF NEUROPATHIC PAIN. CXCR3 IS A CHEMOKINE RECEPTOR. WHETHER IT IS INVOLVED IN NEUROPATHIC PAIN AND HOW IT IS REGULATED AFTER NERVE INJURY REMAIN LARGELY UNKNOWN. OUR STUDY DEMONSTRATES THAT SPINAL NERVE LIGATION DOWNREGULATES THE EXPRESSION OF DNMT3B, WHICH MAY CAUSE DEMETHYLATION OF CXCR3 GENE PROMOTER AND FACILITATE THE BINDING OF CCAAT/ENHANCER BINDING PROTEIN ALPHA WITH CXCR3 PROMOTER AND FURTHER INCREASE CXCR3 EXPRESSION IN SPINAL NEURONS. THE UPREGULATED CXCR3 MAY CONTRIBUTE TO NEUROPATHIC PAIN BY FACILITATING CENTRAL SENSITIZATION. OUR STUDY REVEALS AN EPIGENETIC MECHANISM UNDERLYING CXCR3 EXPRESSION AND ALSO SUGGESTS THAT TARGETING THE EXPRESSION OR ACTIVATION OF CXCR3 SIGNALING MAY OFFER NEW THERAPEUTICS FOR NEUROPATHIC PAIN. 2017 20 4615 37 NERVE INJURY DIMINISHES OPIOID ANALGESIA THROUGH LYSINE METHYLTRANSFERASE-MEDIATED TRANSCRIPTIONAL REPRESSION OF MU-OPIOID RECEPTORS IN PRIMARY SENSORY NEURONS. THE MU-OPIOID RECEPTOR (MOR, ENCODED BY OPRM1) AGONISTS ARE THE MAINSTAY ANALGESICS FOR TREATING MODERATE TO SEVERE PAIN. NERVE INJURY CAUSES DOWN-REGULATION OF MORS IN THE DORSAL ROOT GANGLION (DRG) AND DIMINISHES THE OPIOID EFFECT ON NEUROPATHIC PAIN. HOWEVER, THE EPIGENETIC MECHANISMS UNDERLYING THE DIMINISHED MOR EXPRESSION CAUSED BY NERVE INJURY ARE NOT CLEAR. G9A (ENCODED BY EHMT2), A HISTONE 3 AT LYSINE 9 METHYLTRANSFERASE, IS A KEY CHROMATIN REGULATOR RESPONSIBLE FOR GENE SILENCING. IN THIS STUDY, WE DETERMINED THE ROLE OF G9A IN DIMINISHED MOR EXPRESSION AND OPIOID ANALGESIC EFFECTS IN ANIMAL MODELS OF NEUROPATHIC PAIN. WE FOUND THAT NERVE INJURY IN RATS INDUCED A LONG-LASTING REDUCTION IN THE EXPRESSION LEVEL OF MORS IN THE DRG BUT NOT IN THE SPINAL CORD. NERVE INJURY CONSISTENTLY INCREASED THE ENRICHMENT OF THE G9A PRODUCT HISTONE 3 AT LYSINE 9 DIMETHYLATION IN THE PROMOTER OF OPRM1 IN THE DRG. G9A INHIBITION OR SIRNA KNOCKDOWN FULLY REVERSED MOR EXPRESSION IN THE INJURED DRG AND POTENTIATED THE MORPHINE EFFECT ON PAIN HYPERSENSITIVITY INDUCED BY NERVE INJURY. IN MICE LACKING EHMT2 IN DRG NEURONS, NERVE INJURY FAILED TO REDUCE THE EXPRESSION LEVEL OF MORS AND THE MORPHINE EFFECT. IN ADDITION, G9A INHIBITION OR EHMT2 KNOCKOUT IN DRG NEURONS NORMALIZED NERVE INJURY-INDUCED REDUCTION IN THE INHIBITORY EFFECT OF THE OPIOID ON SYNAPTIC GLUTAMATE RELEASE FROM PRIMARY AFFERENT NERVES. OUR FINDINGS INDICATE THAT G9A CONTRIBUTES CRITICALLY TO TRANSCRIPTIONAL REPRESSION OF MORS IN PRIMARY SENSORY NEURONS IN NEUROPATHIC PAIN. G9A INHIBITORS MAY BE USED TO ENHANCE THE OPIOID ANALGESIC EFFECT IN THE TREATMENT OF CHRONIC NEUROPATHIC PAIN. 2016