1 2884 111 G9A IS ESSENTIAL FOR EPIGENETIC SILENCING OF K(+) CHANNEL GENES IN ACUTE-TO-CHRONIC PAIN TRANSITION. NEUROPATHIC PAIN IS A DEBILITATING CLINICAL PROBLEM AND DIFFICULT TO TREAT. NERVE INJURY CAUSES A LONG-LASTING REDUCTION IN K(+) CHANNEL EXPRESSION IN THE DORSAL ROOT GANGLION (DRG), BUT LITTLE IS KNOWN ABOUT THE EPIGENETIC MECHANISMS INVOLVED. WE FOUND THAT NERVE INJURY INCREASED DIMETHYLATION OF LYS9 ON HISTONE H3 (H3K9ME2) AT KCNA4, KCND2, KCNQ2 AND KCNMA1 PROMOTERS BUT DID NOT AFFECT LEVELS OF DNA METHYLATION ON THESE GENES IN DRGS. NERVE INJURY INCREASED ACTIVITY OF EUCHROMATIC HISTONE-LYSINE N-METHYLTRANSFERASE-2 (G9A), HISTONE DEACETYLASES AND ENHANCER OF ZESTE HOMOLOG-2 (EZH2), BUT ONLY G9A INHIBITION CONSISTENTLY RESTORED K(+) CHANNEL EXPRESSION. SELECTIVE KNOCKOUT OF THE GENE ENCODING G9A IN DRG NEURONS COMPLETELY BLOCKED K(+) CHANNEL SILENCING AND CHRONIC PAIN DEVELOPMENT AFTER NERVE INJURY. REMARKABLY, RNA SEQUENCING ANALYSIS REVEALED THAT G9A INHIBITION NOT ONLY REACTIVATED 40 OF 42 SILENCED GENES ASSOCIATED WITH K(+) CHANNELS BUT ALSO NORMALIZED 638 GENES DOWN- OR UPREGULATED BY NERVE INJURY. THUS G9A HAS A DOMINANT FUNCTION IN TRANSCRIPTIONAL REPRESSION OF K(+) CHANNELS AND IN ACUTE-TO-CHRONIC PAIN TRANSITION AFTER NERVE INJURY. 2015 2 6767 36 ZNF382 CONTROLS MOUSE NEUROPATHIC PAIN VIA SILENCER-BASED EPIGENETIC INHIBITION OF CXCL13 IN DRG NEURONS. NERVE INJURY-INDUCED CHANGES OF GENE EXPRESSION IN DORSAL ROOT GANGLION (DRG) ARE CRITICAL FOR NEUROPATHIC PAIN GENESIS. HOWEVER, HOW THESE CHANGES OCCUR REMAINS ELUSIVE. HERE WE REPORT THE DOWN-REGULATION OF ZINC FINGER PROTEIN 382 (ZNF382) IN INJURED DRG NEURONS AFTER NERVE INJURY. RESCUING THIS DOWN-REGULATION ATTENUATES NOCICEPTIVE HYPERSENSITIVITY. CONVERSELY, MIMICKING THIS DOWN-REGULATION PRODUCES NEUROPATHIC PAIN SYMPTOMS, WHICH ARE ALLEVIATED BY C-X-C MOTIF CHEMOKINE 13 (CXCL13) KNOCKDOWN OR ITS RECEPTOR CXCR5 KNOCKOUT. MECHANISTICALLY, AN IDENTIFIED CIS-ACTING SILENCER AT DISTAL UPSTREAM OF THE CXCL13 PROMOTER SUPPRESSES CXCL13 TRANSCRIPTION VIA BINDING TO ZNF382. BLOCKING THIS BINDING OR GENETICALLY DELETING THIS SILENCER ABOLISHES THE ZNF382 SUPPRESSION ON CXCL13 TRANSCRIPTION AND IMPAIRS ZNF382-INDUCED ANTINOCICEPTION. MOREOVER, ZNF382 DOWN-REGULATION DISRUPTS THE REPRESSIVE EPIGENETIC COMPLEX CONTAINING HISTONE DEACETYLASE 1 AND SET DOMAIN BIFURCATED 1 AT THE SILENCER-PROMOTER LOOP, RESULTING IN CXCL13 TRANSCRIPTIONAL ACTIVATION. THUS, ZNF382 DOWN-REGULATION IS REQUIRED FOR NEUROPATHIC PAIN LIKELY THROUGH SILENCER-BASED EPIGENETIC DISINHIBITION OF CXCL13, A KEY NEUROPATHIC PAIN PLAYER, IN DRG NEURONS. 2021 3 6519 30 TRANSCRIPTIONAL AND EPIGENETIC REGULATION OF INTERLEUKIN-2 GENE IN ACTIVATED T CELLS BY MORPHINE. CHRONIC MORPHINE INHIBITS INTERLEUKIN-2 (IL-2) AT BOTH THE TRANSCRIPTIONAL AND PROTEIN SYNTHESIS LEVELS. THE MOLECULAR MECHANISMS BY WHICH MORPHINE DECREASES IL-2 ARE NOT FULLY UNDERSTOOD. THE PRODUCTION OF IL-2 IS TIGHTLY REGULATED BY SEVERAL TRANSCRIPTION FACTORS THAT BIND TO THE IL-2 PROMOTER. HEREIN, WE SHOW THAT CHRONIC MORPHINE TREATMENT RESULTS IN AN INCREASE IN CAMP LEVELS WITH A CONCURRENT UP-REGULATION OF THE CAMP INDUCIBLE REPRESSOR INDUCIBLE CAMP EARLY REPRESSOR (ICER)/CAMP RESPONSE ELEMENT MODULATOR (CREM) AND DOWN-REGULATION OF P-CAMP-RESPONSE ELEMENT-BINDING PROTEIN (CREB) IN ACTIVATED T CELLS. FURTHERMORE, ICER COMPETES FOR P-CREB BINDING TO THE CAMP-RESPONSIVE ELEMENTS (CRES) SITE. THIS LEADS TO THE UNCOUPLING OF CBP/P300 THEREBY ABROGATING IL-2 TRANSCRIPTION. OVEREXPRESSION OF EITHER ANTISENSE CREM OR CREB PLASMID RESCUED MORPHINE-INDUCED INHIBITION OF IL-2 PROMOTER ACTIVITY AND PROTEIN PRODUCTION. IN ADDITION, WE ALSO FOUND THAT CHRONIC MORPHINE TREATMENT INHIBITED THE ACETYLATION AND TRIMETHYLATION OF HISTONES AND DECREASED BOTH DNA DEMETHYLATION AND ACCESSIBILITY OF THE IL-2 PROMOTER. THESE FINDINGS SUGGEST THAT CHRONIC MORPHINE TREATMENT MAY FUNCTION THROUGH BOTH TRANSCRIPTIONAL AND EPIGENETIC MECHANISMS TO INHIBIT IL-2 PRODUCTION. 2007 4 4160 42 MECP2 EPIGENETIC SILENCING OF OPRM1 GENE IN PRIMARY SENSORY NEURONS UNDER NEUROPATHIC PAIN CONDITIONS. OPIOIDS ARE THE LAST OPTION FOR THE PHARMACOLOGICAL TREATMENT OF NEUROPATHIC PAIN, BUT THEIR ANTINOCICEPTIVE EFFECTS ARE LIMITED. DECREASED MU OPIOID RECEPTOR (MOR) EXPRESSION IN THE PERIPHERAL NERVOUS SYSTEM MAY CONTRIBUTE TO THIS. HERE, WE SHOWED THAT NERVE INJURY INDUCED HYPERMETHYLATION OF THE OPRM1 GENE PROMOTER AND AN INCREASED EXPRESSION OF METHYL-CPG BINDING PROTEIN 2 (MECP2) IN INJURED DORSAL ROOT GANGLION (DRG). THE DOWNREGULATION OF MOR IN THE DRG IS CLOSELY RELATED TO THE AUGMENTATION OF MECP2, AN EPIGENETIC REPRESSOR, WHICH COULD RECRUIT HDAC1 AND BIND TO THE METHYLATED REGIONS OF THE OPRM1 GENE PROMOTER. MECP2 KNOCKDOWN RESTORED THE EXPRESSION OF MOR IN INJURED DRG AND ENHANCED THE ANALGESIC EFFECT OF MORPHINE, WHILE THE MIMICKING OF THIS INCREASE VIA THE INTRATHECAL INFUSION OF VIRAL VECTOR-MEDIATED MECP2 WAS SUFFICIENT TO REDUCE MOR IN THE DRG. MOREOVER, HDAC1 INHIBITION WITH SUBEROYLANILIDE HYDROXAMIC ACID, AN HDAC INHIBITOR, ALSO PREVENTED MOR REDUCTION IN THE DRG OF NEUROPATHIC PAIN MICE, CONTRIBUTING TO THE AUGMENTATION OF MORPHINE ANALGESIA EFFECTS. MECHANISTICALLY, UPREGULATED MECP2 PROMOTES THE BINDING OF A HIGH LEVEL OF HDCA1 TO HYPERMETHYLATED REGIONS OF THE OPRM1 GENE PROMOTER, REDUCES THE ACETYLATION OF HISTONE H3 (ACH3) LEVELS OF THE OPRM1 GENE PROMOTER, AND ATTENUATES OPRM1 TRANSCRIPTION IN INJURED DRG. THUS, UPREGULATED MECP2 AND HDAC1 IN OPRM1 GENE PROMOTER SITES, NEGATIVELY REGULATES MOR EXPRESSION IN INJURED DRG, MITIGATING THE ANALGESIC EFFECT OF THE OPIOIDS. TARGETING MECP2/HDAC1 MAY THUS PROVIDE A NEW SOLUTION FOR IMPROVING THE THERAPEUTIC EFFECT OF OPIOIDS IN A CLINICAL SETTING. 2021 5 1166 32 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 6 4615 45 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 7 4163 31 MECP2 REPRESSION OF G9A IN REGULATION OF PAIN AND MORPHINE REWARD. OPIOIDS ARE COMMONLY USED FOR PAIN RELIEF, BUT THEIR STRONG REWARDING EFFECTS DRIVE OPIOID MISUSE AND ABUSE. HOW PAIN AFFECTS THE LIABILITY OF OPIOID ABUSE IS UNKNOWN AT PRESENT. IN THIS STUDY, WE IDENTIFIED AN EPIGENETIC REGULATING CASCADE ACTIVATED BY BOTH PAIN AND THE OPIOID MORPHINE. BOTH PERSISTENT PAIN AND REPEATED MORPHINE UPREGULATED THE TRANSCRIPTIONAL REGULATOR MECP2 IN MOUSE CENTRAL NUCLEUS OF THE AMYGDALA (CEA). CHROMATIN IMMUNOPRECIPITATION ANALYSIS REVEALED THAT MECP2 BOUND TO AND REPRESSED THE TRANSCRIPTIONAL REPRESSOR HISTONE DIMETHYLTRANSFERASE G9A, REDUCING G9A-CATALYZED REPRESSIVE MARK H3K9ME2 IN CEA. REPRESSION OF G9A ACTIVITY INCREASED EXPRESSION OF BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF). BEHAVIORALLY, PERSISTENT INFLAMMATORY PAIN INCREASED THE SENSITIVITY TO ACQUIRING MORPHINE-INDUCED, REWARD-RELATED BEHAVIOR OF CONDITIONED PLACE PREFERENCE IN MICE. LOCAL VIRAL VECTOR-MEDIATED MECP2 OVEREXPRESSION, CRE-INDUCED G9A KNOCKDOWN, AND CEA APPLICATION OF BDNF MIMICKED, WHEREAS MECP2 KNOCKDOWN INHIBITED, THE PAIN EFFECT. THESE RESULTS SUGGEST THAT MECP2 DIRECTLY REPRESSES G9A AS A SHARED MECHANISM IN CENTRAL AMYGDALA FOR REGULATION OF EMOTIONAL RESPONSES TO PAIN AND OPIOID REWARD, AND FOR THEIR BEHAVIORAL INTERACTION. 2014 8 2825 34 FLOW-DEPENDENT EPIGENETIC REGULATION OF IGFBP5 EXPRESSION BY H3K27ME3 CONTRIBUTES TO ENDOTHELIAL ANTI-INFLAMMATORY EFFECTS. RATIONALE: ATHEROSCLEROSIS IS A CHRONIC INFLAMMATORY AND EPIGENETIC DISEASE THAT IS INFLUENCED BY DIFFERENT PATTERNS OF BLOOD FLOW. HOWEVER, THE EPIGENETIC MECHANISM WHEREBY ATHEROPROTECTIVE FLOW CONTROLS ENDOTHELIAL GENE PROGRAMMING REMAINS ELUSIVE. HERE, WE INVESTIGATED THE POSSIBILITY THAT FLOW ALTERS ENDOTHELIAL GENE EXPRESSION THROUGH EPIGENETIC MECHANISMS. METHODS: EN FACE STAINING AND WESTERN BLOT WERE USED TO DETECT PROTEIN EXPRESSION. REAL-TIME PCR WAS USED TO DETERMINE RELATIVE GENE EXPRESSION. RNA-SEQUENCING OF HUMAN UMBILICAL VEIN ENDOTHELIAL CELLS TREATED WITH SIRNA OF ENHANCER OF ZESTE HOMOLOG 2 (EZH2) OR LAMINAR FLOW WAS USED FOR TRANSCRIPTIONAL PROFILING. RESULTS: WE FOUND THAT TRIMETHYLATION OF HISTONE 3 LYSINE 27 (H3K27ME3), A REPRESSIVE EPIGENETIC MARK THAT ORCHESTRATES GENE REPRESSION, WAS REDUCED IN LAMINAR FLOW AREAS OF MOUSE AORTA AND FLOW-TREATED HUMAN ENDOTHELIAL CELLS. THE DECREASE OF H3K27ME3 PARALLELED A REDUCTION IN THE EPIGENETIC "WRITER"-EZH2, THE CATALYTIC SUBUNIT OF THE POLYCOMB REPRESSIVE COMPLEX 2 (PRC2). MOREOVER, LAMINAR FLOW DECREASED EXPRESSION OF EZH2 VIA MECHANOSENSITIVE MIR101. GENOME-WIDE TRANSCRIPTOME PROFILING STUDIES IN ENDOTHELIAL CELLS TREATED WITH EZH2 SIRNA AND FLOW REVEALED THE UPREGULATION OF NOVEL MECHANOSENSITIVE GENE IGFBP5 (INSULIN-LIKE GROWTH FACTOR-BINDING PROTEIN 5), WHICH IS EPIGENETICALLY SILENCED BY H3K27ME3. FUNCTIONALLY, INHIBITION OF H3K27ME3 BY EZH2 SIRNA OR GSK126 (A SPECIFIC EZH2 INHIBITOR) REDUCED H3K27ME3 LEVELS AND MONOCYTE ADHESION TO ENDOTHELIAL CELLS. ADENOVIRAL OVEREXPRESSION OF IGFBP5 ALSO RECAPITULATED THE ANTI-INFLAMMATORY EFFECTS OF H3K27ME3 INHIBITION. MORE IMPORTANTLY, WE OBSERVED EZH2 UPREGULATION, AND IGFBP5 DOWNREGULATION, IN ADVANCED ATHEROSCLEROTIC PLAQUES FROM HUMAN PATIENTS. CONCLUSION: TAKEN TOGETHER, OUR FINDINGS REVEAL THAT ATHEROPROTECTIVE FLOW REDUCES H3K27ME3 AS A CHROMATIN-BASED MECHANISM TO AUGMENT THE EXPRESSION OF GENES THAT CONFER AN ANTI-INFLAMMATORY RESPONSE IN THE ENDOTHELIUM. OUR STUDY EXEMPLIFIES FLOW-DEPENDENT EPIGENETIC REGULATION OF ENDOTHELIAL GENE EXPRESSION, AND ALSO SUGGESTS THAT TARGETING THE EZH2/H3K27ME3/IGFBP5 PATHWAY MAY OFFER NOVEL THERAPEUTICS FOR INFLAMMATORY DISORDERS SUCH AS ATHEROSCLEROSIS. 2018 9 4546 28 MUTANT P53 REGULATES ENHANCER-ASSOCIATED H3K4 MONOMETHYLATION THROUGH INTERACTIONS WITH THE METHYLTRANSFERASE MLL4. MONOMETHYLATION OF HISTONE H3 LYSINE 4 (H3K4ME1) IS ENRICHED AT ENHANCERS THAT ARE PRIMED FOR ACTIVATION AND THE LEVELS OF THIS HISTONE MARK ARE FREQUENTLY ALTERED IN VARIOUS HUMAN CANCERS. YET, HOW ALTERATIONS IN H3K4ME1 ARE ESTABLISHED AND THE CONSEQUENCES OF THESE EPIGENETIC CHANGES IN TUMORIGENESIS ARE NOT WELL UNDERSTOOD. USING CHIP-SEQ IN HUMAN COLON CANCER CELLS, WE DEMONSTRATE THAT MUTANT P53 DEPLETION RESULTS IN DECREASED H3K4ME1 LEVELS AT ACTIVE ENHANCERS THAT REVEAL A STRIKING COLOCALIZATION OF MUTANT P53 AND THE H3K4 MONOMETHYLTRANSFERASE MLL4 FOLLOWING CHRONIC TUMOR NECROSIS FACTOR ALPHA (TNFALPHA) SIGNALING. WE FURTHER REVEAL THAT MUTANT P53 FORMS PHYSIOLOGICAL ASSOCIATIONS AND DIRECT INTERACTIONS WITH MLL4 AND PROMOTES THE ENHANCER BINDING OF MLL4, WHICH IS REQUIRED FOR TNFALPHA-INDUCIBLE H3K4ME1 AND HISTONE H3 LYSINE 27 ACETYLATION (H3K27AC) LEVELS, ENHANCER-DERIVED TRANSCRIPT (ERNA) SYNTHESIS, AND MUTANT P53-DEPENDENT TARGET GENE ACTIVATION. COMPLEMENTARY IN VITRO STUDIES WITH RECOMBINANT CHROMATIN AND PURIFIED PROTEINS DEMONSTRATE THAT BINDING OF THE MLL3/4 COMPLEX AND H3K4ME1 DEPOSITION IS ENHANCED BY MUTANT P53 AND P300-MEDIATED ACETYLATION, WHICH IN TURN REFLECTS A MLL3/4-DEPENDENT ENHANCEMENT OF MUTANT P53 AND P300-DEPENDENT TRANSCRIPTIONAL ACTIVATION. COLLECTIVELY, OUR FINDINGS ESTABLISH A MECHANISM IN WHICH MUTANT P53 COOPERATES WITH MLL4 TO REGULATE ABERRANT ENHANCER ACTIVITY AND TUMOR-PROMOTING GENE EXPRESSION IN RESPONSE TO CHRONIC IMMUNE SIGNALING. 2018 10 3082 37 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 11 1654 36 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 12 1906 29 ENHANCER OF ZESTE HOMOLOG 2-CATALYSED H3K27 TRIMETHYLATION PLAYS A KEY ROLE IN ACUTE-ON-CHRONIC LIVER FAILURE VIA TNF-MEDIATED PATHWAY. ACUTE-ON-CHRONIC LIVER FAILURE IS MAINLY DUE TO HOST IMMUNITY SELF-DESTRUCTION. THE HISTONE H3 LYSINE 27 (H3K27) TRIMETHYLATING ENZYME, ENHANCER OF ZESTE HOMOLOG 2 (EZH2) MEDIATES EPIGENETIC SILENCING OF GENE EXPRESSION AND REGULATES IMMUNITY, ALSO INVOLVES PATHOGENESIS OF SEVERAL LIVER DISEASES. THE CURRENT STUDY WAS TO DETERMINE THE ROLE OF METHYLTRANSFERASE EZH2 AND ITS CATALYSED H3K27 TRIMETHYLATION (H3K27ME3) IN LIVER FAILURE, AND TO FURTHER INVESTIGATE THE POTENTIAL TARGET FOR LIVER FAILURE TREATMENT. EZH2 AND ITS CATALYSED H3K27ME3 WERE DETERMINED IN PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMC) FROM LIVER FAILURE PATIENTS AND KUPFFER CELLS FROM EXPERIMENTAL MICE. FURTHERMORE, GSK126 (AN INHIBITOR FOR EZH2 TRIMETHYLATION FUNCTION) WAS APPLIED IN LIVER FAILURE MICE IN VIVO, AND LIPOPOLYSACCHARIDE-STIMULATED MONONUCLEAR CELLS IN VITRO. EZH2 AND H3K27ME3 WERE SIGNIFICANTLY UPREGULATED IN HUMAN PBMC FROM LIVER FAILURE PATIENTS OR MURINE KUPFFER CELLS FROM THE LIVER FAILURE ANIMALS, RESPECTIVELY. GSK126 AMELIORATED DISEASE SEVERITY IN LIVER FAILURE MICE, WHICH MAYBE ATTRIBUTE TO DOWN-REGULATE CIRCULATING AND HEPATIC PROINFLAMMATORY CYTOKINES, ESPECIALLY TNF VIA REDUCING H3K27ME3. IN-DEPTH CHROMATIN IMMUNOPRECIPITATION ANALYSIS UNRAVELLED THAT DECREASED ENRICHMENT OF H3K27ME3 ON TNF PROMOTOR, RESULTING IN TNF ELEVATION IN KUPFFER CELLS FROM LIVER FAILURE MICE. NUCLEAR FACTOR KAPPA B (NF-KAPPAB) AND PROTEIN KINASE B (AKT) SIGNALLING PATHWAYS WERE ACTIVATED UPON LIPOPOLYSACCHARIDE STIMULATION, BUT ATTENUATED BY USING GSK126, ACCOMPANIED WITH DECREASED TNF IN VITRO. IN CONCLUSION, EZH2 AND H3K27ME3 CONTRIBUTED TO THE PATHOGENESIS OF LIVER FAILURE VIA TRIGGERING TNF AND OTHER INDISPENSABLE PROINFLAMMATORY CYTOKINES. EZH2 WAS TO MODIFY H3K27ME3 ENRICHMENT, AS WELL AS, ACTIVATION OF THE DOWNSTREAM NF-KAPPAB AND AKT SIGNALLING PATHWAYS. 2018 13 2370 28 EPIGENETIC REGULATION OF THE ALTERNATIVELY ACTIVATED MACROPHAGE PHENOTYPE. ALTERNATIVELY ACTIVATED (M2) MACROPHAGES PLAY CRITICAL ROLES IN DIVERSE CHRONIC DISEASES, INCLUDING PARASITE INFECTIONS, CANCER, AND ALLERGIC RESPONSES. HOWEVER, LITTLE IS KNOWN ABOUT THE ACQUISITION AND MAINTENANCE OF THEIR PHENOTYPE. WE REPORT THAT M2-MACROPHAGE MARKER GENES ARE EPIGENETICALLY REGULATED BY RECIPROCAL CHANGES IN HISTONE H3 LYSINE-4 (H3K4) AND HISTONE H3 LYSINE-27 (H3K27) METHYLATION; AND THE LATTER METHYLATION MARKS ARE REMOVED BY THE H3K27 DEMETHYLASE JUMONJI DOMAIN CONTAINING 3 (JMJD3). WE FOUND THAT CONTINUOUS INTERLEUKIN-4 (IL-4) TREATMENT LEADS TO DECREASED H3K27 METHYLATION, AT THE PROMOTER OF M2 MARKER GENES, AND A CONCOMITANT INCREASE IN JMJD3 EXPRESSION. FURTHERMORE, WE DEMONSTRATE THAT IL-4-DEPENDENT JMJD3 EXPRESSION IS MEDIATED BY STAT6, A MAJOR TRANSCRIPTION FACTOR OF IL-4-MEDIATED SIGNALING. AFTER IL-4 STIMULATION, ACTIVATED STAT6 IS INCREASED AND BINDS TO CONSENSUS SITES AT THE JMJD3 PROMOTER. INCREASED JMJD3 CONTRIBUTES TO THE DECREASE OF H3K27 DIMETHYLATION AND TRIMETHYLATION (H3K27ME2/3) MARKS AS WELL AS THE TRANSCRIPTIONAL ACTIVATION OF SPECIFIC M2 MARKER GENES. THE DECREASE IN H3K27ME2/3 AND INCREASE IN JMJD3 RECRUITMENT WERE CONFIRMED BY IN VIVO STUDIES USING A SCHISTOSOMA MANSONI EGG-CHALLENGED MOUSE MODEL, A WELL-STUDIED SYSTEM KNOWN TO SUPPORT AN M2 PHENOTYPE. COLLECTIVELY, THESE DATA INDICATE THAT CHROMATIN REMODELING IS MECHANISTICALLY IMPORTANT IN THE ACQUISITION OF THE M2-MACROPHAGE PHENOTYPE. 2009 14 1652 29 DOPAMINE SIGNALING LEADS TO LOSS OF POLYCOMB REPRESSION AND ABERRANT GENE ACTIVATION IN EXPERIMENTAL PARKINSONISM. POLYCOMB GROUP (PCG) PROTEINS BIND TO AND REPRESS GENES IN EMBRYONIC STEM CELLS THROUGH LINEAGE COMMITMENT TO THE TERMINAL DIFFERENTIATED STATE. PCG REPRESSED GENES ARE COMMONLY CHARACTERIZED BY THE PRESENCE OF THE EPIGENETIC HISTONE MARK H3K27ME3, CATALYZED BY THE POLYCOMB REPRESSIVE COMPLEX 2. HERE, WE PRESENT IN VIVO EVIDENCE FOR A PREVIOUSLY UNRECOGNIZED PLASTICITY OF PCG-REPRESSED GENES IN TERMINALLY DIFFERENTIATED BRAIN NEURONS OF PARKISONIAN MICE. WE SHOW THAT ACUTE ADMINISTRATION OF THE DOPAMINE PRECURSOR, L-DOPA, INDUCES A REMARKABLE INCREASE IN H3K27ME3S28 PHOSPHORYLATION. THE INDUCTION OF THE H3K27ME3S28P HISTONE MARK SPECIFICALLY OCCURS IN MEDIUM SPINY NEURONS EXPRESSING DOPAMINE D1 RECEPTORS AND IS DEPENDENT ON MSK1 KINASE ACTIVITY AND DARPP-32-MEDIATED INHIBITION OF PROTEIN PHOSPHATASE-1. CHROMATIN IMMUNOPRECIPITATION (CHIP) EXPERIMENTS SHOWED THAT INCREASED H3K27ME3S28P WAS ACCOMPANIED BY REDUCED PCG BINDING TO REGULATORY REGIONS OF GENES. AN ANALYSIS OF THE GENOME WIDE DISTRIBUTION OF L-DOPA-INDUCED H3K27ME3S28 PHOSPHORYLATION BY CHIP SEQUENCING (CHIP-SEQ) IN COMBINATION WITH EXPRESSION ANALYSIS BY RNA-SEQUENCING (RNA-SEQ) SHOWED THAT THE INDUCTION OF H3K27ME3S28P CORRELATED WITH INCREASED EXPRESSION OF A SUBSET OF PCG REPRESSED GENES. WE FOUND THAT INDUCTION OF H3K27ME3S28P PERSISTED DURING CHRONIC L-DOPA ADMINISTRATION TO PARKISONIAN MICE AND CORRELATED WITH ABERRANT GENE EXPRESSION. WE PROPOSE THAT DOPAMINERGIC TRANSMISSION CAN ACTIVATE PCG REPRESSED GENES IN THE ADULT BRAIN AND THEREBY CONTRIBUTE TO LONG-TERM MALADAPTIVE RESPONSES INCLUDING THE MOTOR COMPLICATIONS, OR DYSKINESIA, CAUSED BY PROLONGED ADMINISTRATION OF L-DOPA IN PARKINSON'S DISEASE. 2014 15 2425 27 EPIGENETIC SILENCING OF IRF1 DYSREGULATES TYPE III INTERFERON RESPONSES TO RESPIRATORY VIRUS INFECTION IN EPITHELIAL TO MESENCHYMAL TRANSITION. CHRONIC OXIDATIVE INJURY PRODUCED BY AIRWAY DISEASE TRIGGERS A TRANSFORMING GROWTH FACTOR-BETA (TGF-BETA)-MEDIATED EPIGENETIC REPROGRAMMING KNOWN AS THE EPITHELIAL-MESENCHYMAL TRANSITION (EMT). WE OBSERVE THAT EMT SILENCES PROTECTIVE MUCOSAL INTERFERON (IFN)-I AND III PRODUCTION ASSOCIATED WITH ENHANCED RHINOVIRUS (RV) AND RESPIRATORY SYNCYTIAL VIRUS (RSV) REPLICATION. MESENCHYMAL TRANSITIONED CELLS ARE DEFECTIVE IN INDUCIBLE INTERFERON REGULATORY FACTOR 1 (IRF1) EXPRESSION BY OCCLUDING RELA AND IRF3 ACCESS TO THE PROMOTER. IRF1 IS NECESSARY FOR THE EXPRESSION OF TYPE III IFNS (IFNLS 1 AND 2/3). INDUCED BY THE EMT, ZINC FINGER E-BOX BINDING HOMEOBOX 1 (ZEB1) BINDS AND SILENCES IRF1. ECTOPIC ZEB1 IS SUFFICIENT FOR IRF1 SILENCING, WHEREAS ZEB1 KNOCKDOWN PARTIALLY RESTORES IRF1-IFNL UPREGULATION. ZEB1 SILENCES IRF1 THROUGH THE CATALYTIC ACTIVITY OF THE ENHANCER OF ZESTE 2 POLYCOMB REPRESSIVE COMPLEX 2 SUBUNIT (EZH2), FORMING REPRESSIVE H3K27(ME3) MARKS. WE OBSERVE THAT IRF1 EXPRESSION IS MEDIATED BY ZEB1 DE-REPRESSION, AND OUR STUDY DEMONSTRATES HOW AIRWAY REMODELLING/FIBROSIS IS ASSOCIATED WITH A DEFECTIVE MUCOSAL ANTIVIRAL RESPONSE THROUGH ZEB1-INITIATED EPIGENETIC SILENCING. 2017 16 2785 39 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 17 2885 42 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 18 3175 27 H2AX PHOSPHORYLATION REGULATED BY P38 IS INVOLVED IN BIM EXPRESSION AND APOPTOSIS IN CHRONIC MYELOGENOUS LEUKEMIA CELLS INDUCED BY IMATINIB. INCREASING EVIDENCE SUGGESTS THAT HISTONE H2AX PLAYS A CRITICAL ROLE IN REGULATION OF TUMOR CELL APOPTOSIS AND ACTS AS A NOVEL HUMAN TUMOR SUPPRESSOR PROTEIN. HOWEVER, THE ACTION OF H2AX IN CHRONIC MYELOGENOUS LEUKEMIA (CML) CELLS IS UNKNOWN. THE DETAILED MECHANISM AND EPIGENETIC REGULATION BY H2AX REMAIN ELUSIVE IN CANCER CELLS. HERE, WE REPORT THAT H2AX WAS INVOLVED IN APOPTOSIS OF CML CELLS. OVEREXPRESSION OF H2AX INCREASED APOPTOTIC SENSITIVITY OF CML CELLS (K562) INDUCED BY IMATINIB. HOWEVER, OVEREXPRESSION OF SER139-MUTATED H2AX (BLOCKING PHOSPHORYLATION) DECREASED SENSITIVITY OF K562 CELLS TO APOPTOSIS. SIMILARLY, KNOCKDOWN OF H2AX MADE K562 CELLS RESISTANT TO APOPTOTIC INDUCTION. THESE RESULTS REVEALED THAT THE FUNCTION OF H2AX INVOLVED IN APOPTOSIS IS STRICTLY RELATED TO ITS PHOSPHORYLATION (SER139). OUR DATA FURTHER INDICATED THAT IMATINIB MAY STIMULATE MITOGEN-ACTIVATED PROTEIN KINASE (MAPK) FAMILY MEMBER P38, AND H2AX PHOSPHORYLATION FOLLOWED A SIMILAR TIME COURSE, SUGGESTING A PARALLEL RESPONSE. H2AX PHOSPHORYLATION CAN BE BLOCKED BY P38 SIRNA OR ITS INHIBITOR. THESE DATA DEMONSTRATED THAT H2AX PHOSPHORYLATION WAS REGULATED BY P38 MAPK PATHWAY IN K562 CELLS. HOWEVER, THE P38 MAPK DOWNSTREAM, MITOGEN- AND STRESS-ACTIVATED PROTEIN KINASE-1 AND -2, WHICH PHOSPHORYLATED HISTONE H3, WERE NOT REQUIRED FOR H2AX PHOSPHORYLATION DURING APOPTOSIS. FINALLY, WE PROVIDED EPIGENETIC EVIDENCE THAT H2AX PHOSPHORYLATION REGULATED APOPTOSIS-RELATED GENE BIM EXPRESSION. BLOCKING OF H2AX PHOSPHORYLATION INHIBITED BIM GENE EXPRESSION. TAKEN TOGETHER, THESE DATA DEMONSTRATED THAT H2AX PHOSPHORYLATION REGULATED BY P38 IS INVOLVED IN BIM EXPRESSION AND APOPTOSIS IN CML CELLS INDUCED BY IMATINIB. 2014 19 717 37 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 20 2783 33 EZH2 METHYLTRANSFERASE REGULATES NEUROINFLAMMATION AND NEUROPATHIC PAIN. RECENT STUDIES BY US AND OTHERS HAVE SHOWN THAT ENHANCER OF ZESTE HOMOLOG-2 (EZH2), A HISTONE METHYLTRANSFERASE, IN GLIAL CELLS REGULATES THE GENESIS OF NEUROPATHIC PAIN BY MODULATING THE PRODUCTION OF PROINFLAMMATORY CYTOKINES AND CHEMOKINES. IN THIS REVIEW, WE SUMMARIZE RECENT ADVANCES IN THIS RESEARCH AREA. EZH2 IS A SUBUNIT OF POLYCOMB REPRESSIVE COMPLEX 2 (PRC2), WHICH PRIMARILY SERVES AS A HISTONE METHYLTRANSFERASE TO CATALYZE METHYLATION OF HISTONE 3 ON LYSINE 27 (H3K27), ULTIMATELY RESULTING IN TRANSCRIPTIONAL REPRESSION. ANIMALS WITH NEUROPATHIC PAIN EXHIBIT INCREASED EZH2 ACTIVITY AND NEUROINFLAMMATION OF THE INJURED NERVE, SPINAL CORD, AND ANTERIOR CINGULATE CORTEX. INHIBITION OF EZH2 WITH DZNEP OR GSK-126 AMELIORATES NEUROINFLAMMATION AND NEUROPATHIC PAIN. EZH2 PROTEIN EXPRESSION INCREASES UPON ACTIVATION OF TOLL-LIKE RECEPTOR 4 AND CALCITONIN GENE-RELATED PEPTIDE RECEPTORS, DOWNREGULATION OF MIR-124-3P AND MIR-378 MICRORNAS, OR UPREGULATION OF LNCENC1 AND MALAT1 LONG NONCODING RNAS. GENES SUPPRESSED BY EZH2 INCLUDE SUPPRESSOR OF CYTOKINE SIGNALING 3 (SOCS3), NUCLEAR FACTOR (ERYTHROID-DERIVED 2)-LIKE-2 FACTOR (NRF2), MIR-29B-3P, MIR-146A-5P, AND BRAIN-SPECIFIC ANGIOGENESIS INHIBITOR 1 (BAI1). PRO-INFLAMMATORY MEDIATORS FACILITATE NEURONAL ACTIVATION ALONG PAIN-SIGNALING PATHWAYS BY SENSITIZING NOCICEPTORS IN THE PERIPHERY, AS WELL AS ENHANCING EXCITATORY SYNAPTIC ACTIVITIES AND SUPPRESSING INHIBITORY SYNAPTIC ACTIVITIES IN THE CNS. THESE STUDIES COLLECTIVELY REVEAL THAT EZH2 IS IMPLICATED IN SIGNALING PATHWAYS KNOWN TO BE KEY PLAYERS IN THE PROCESS OF NEUROINFLAMMATION AND GENESIS OF NEUROPATHIC PAIN. THEREFORE, TARGETING THE EZH2 SIGNALING PATHWAY MAY OPEN A NEW AVENUE TO MITIGATE NEUROINFLAMMATION AND NEUROPATHIC PAIN. 2023