1 1652 133 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 2 4230 38 METHYLATION OF POLYCOMB TARGET GENES IN INTESTINAL CANCER IS MEDIATED BY INFLAMMATION. EPIGENETIC CHANGES ARE STRONGLY ASSOCIATED WITH CANCER DEVELOPMENT. DNA HYPERMETHYLATION IS ASSOCIATED WITH GENE SILENCING AND IS OFTEN OBSERVED IN CPG ISLANDS. RECENTLY, IT WAS SUGGESTED THAT ABERRANT CPG ISLAND METHYLATION IN TUMORS IS DIRECTED BY POLYCOMB (PCG) PROTEINS. HOWEVER, SPECIFIC MECHANISMS RESPONSIBLE FOR METHYLATION OF PCG TARGET GENES IN CANCER ARE NOT KNOWN. CHRONIC INFECTION AND INFLAMMATION CONTRIBUTE TO UP TO 25% OF ALL CANCERS WORLDWIDE. USING GLUTATHIONE PEROXIDASE, GPX1 AND GPX2, DOUBLE KNOCKOUT (GPX1/2-KO) MICE AS A MODEL OF INFLAMMATORY BOWEL DISEASE PREDISPOSING TO INTESTINAL CANCER, WE ANALYZED GENOME-WIDE DNA METHYLATION IN THE MOUSE ILEUM DURING CHRONIC INFLAMMATION, AGING, AND CANCER. WE FOUND THAT INFLAMMATION LEADS TO ABERRANT DNA METHYLATION IN PCG TARGET GENES, WITH 70% OF THE APPROXIMATELY 250 GENES METHYLATED IN THE INFLAMED TISSUE BEING PCG TARGETS IN EMBRYONIC STEM CELLS AND 59% OF THE METHYLATED GENES BEING MARKED BY H3K27 TRIMETHYLATION IN THE ILEUM OF ADULT WILD-TYPE MICE. ACQUISITION OF DNA METHYLATION AT CPG ISLANDS IN THE ILEUM OF GPX1/2-KO MICE FREQUENTLY CORRELATES WITH LOSS OF H3K27 TRIMETHYLATION AT THE SAME LOCI. INFLAMMATION-ASSOCIATED DNA METHYLATION OCCURS PREFERENTIALLY IN TISSUE-SPECIFIC SILENT GENES AND, IMPORTANTLY, IS MUCH MORE FREQUENTLY REPRESENTED IN TUMORS THAN IS AGE-DEPENDENT DNA METHYLATION. SIXTY PERCENT OF ABERRANT METHYLATION FOUND IN TUMORS IS ALSO PRESENT IN THE INFLAMED TISSUE. IN SUMMARY, INFLAMMATION CREATES A SIGNATURE OF ABERRANT DNA METHYLATION, WHICH IS OBSERVED LATER IN THE MALIGNANT TISSUE AND IS DIRECTED BY THE PCG COMPLEX. 2008 3 1161 45 CONTINUOUS DEVELOPMENTAL AND EARLY LIFE TRICHLOROETHYLENE EXPOSURE PROMOTED DNA METHYLATION ALTERATIONS IN POLYCOMB PROTEIN BINDING SITES IN EFFECTOR/MEMORY CD4(+) T CELLS. TRICHLOROETHYLENE (TCE) IS AN INDUSTRIAL SOLVENT AND DRINKING WATER POLLUTANT ASSOCIATED WITH CD4(+) T CELL-MEDIATED AUTOIMMUNITY. IN OUR MOUSE MODEL, DISCONTINUATION OF TCE EXPOSURE DURING ADULTHOOD AFTER DEVELOPMENTAL EXPOSURE DID NOT PREVENT IMMUNOTOXICITY. TO DETERMINE WHETHER PERSISTENT EFFECTS WERE LINKED TO EPIGENETIC CHANGES WE CONDUCTED WHOLE GENOME REDUCED REPRESENTATION BISULFITE SEQUENCING (RRBS) TO EVALUATE METHYLATION OF CPG SITES IN AUTOSOMAL CHROMOSOMES IN ACTIVATED EFFECTOR/MEMORY CD4(+) T CELLS. FEMALE MRL+/+ MICE WERE EXPOSED TO VEHICLE CONTROL OR TCE IN THE DRINKING WATER FROM GESTATION UNTIL ~37 WEEKS OF AGE [POSTNATAL DAY (PND) 259]. IN A SUBSET OF MICE, TCE EXPOSURE WAS DISCONTINUED AT ~22 WEEKS OF AGE (PND 154). AT PND 259, RRBS ASSESSMENT REVEALED MORE GLOBAL METHYLATION CHANGES IN THE CONTINUOUS EXPOSURE GROUP VS. THE DISCONTINUOUS EXPOSURE GROUP. A MAJORITY OF THE DIFFERENTIALLY METHYLATED CPG REGIONS (DMRS) ACROSS PROMOTERS, ISLANDS, AND REGULATORY ELEMENTS WERE HYPERMETHYLATED (~90%). HOWEVER, CONTINUOUS DEVELOPMENTAL TCE EXPOSURE ALTERED THE METHYLATION OF 274 CPG SITES IN PROMOTERS AND CPG ISLANDS. IN CONTRAST, ONLY 4 CPG ISLAND REGIONS WERE DIFFERENTIALLY METHYLATED (HYPERMETHYLATED) IN THE DISCONTINUOUS GROUP. INTERESTINGLY, 2 OF THESE 4 SITES WERE ALSO HYPERMETHYLATED IN THE CONTINUOUS EXPOSURE GROUP, AND BOTH OF THESE ISLAND REGIONS ARE ASSOCIATED WITH LYSINE 27 ON HISTONE H3 (H3K27) INVOLVED IN POLYCOMB COMPLEX-DEPENDENT TRANSCRIPTIONAL REPRESSION VIA H3K27 TRI-METHYLATION. CPG SITES WERE OVERLAPPED WITH THE OPEN REGULATORY ANNOTATION DATABASE. UNLIKE THE DISCONTINUOUS GROUP, CONTINUOUS TCE TREATMENT RESULTED IN 129 DMRS INCLUDING 12 UNIQUE TRANSCRIPTION FACTORS AND REGULATORY ELEMENTS; 80% OF WHICH WERE ENRICHED FOR ONE OR MORE POLYCOMB GROUP (PCG) PROTEIN BINDING REGIONS (I.E., SUZ12, EZH2, JARID2, AND MTF2). PATHWAY ANALYSIS OF THE DMRS INDICATED THAT TCE PRIMARILY ALTERED THE METHYLATION OF GENES ASSOCIATED WITH REGULATION OF CELLULAR METABOLISM AND CELL SIGNALING. THE RESULTS DEMONSTRATED THAT CONTINUOUS DEVELOPMENTAL EXPOSURE TO TCE DIFFERENTIALLY METHYLATED BINDING SITES OF PCG PROTEINS IN EFFECTOR/MEMORY CD4(+) CELLS. THERE WERE MINIMAL YET POTENTIALLY BIOLOGICALLY SIGNIFICANT EFFECTS THAT OCCURRED WHEN EXPOSURE WAS DISCONTINUED. THESE RESULTS POINT TOWARD A NOVEL MECHANISM BY WHICH CHRONIC DEVELOPMENTAL TCE EXPOSURE MAY ALTER TERMINALLY DIFFERENTIATED CD4(+) T CELL FUNCTION IN ADULTHOOD. 2019 4 6176 38 THE HISTONE H3 LYSINE-27 DEMETHYLASE JMJD3 LINKS INFLAMMATION TO INHIBITION OF POLYCOMB-MEDIATED GENE SILENCING. EPIGENETIC CHROMATIN MARKS RESTRICT THE ABILITY OF DIFFERENTIATED CELLS TO CHANGE GENE EXPRESSION PROGRAMS IN RESPONSE TO ENVIRONMENTAL CUES AND TO TRANSDIFFERENTIATE. POLYCOMB GROUP (PCG) PROTEINS MEDIATE GENE SILENCING AND REPRESS TRANSDIFFERENTIATION IN A MANNER DEPENDENT ON HISTONE H3 LYSINE 27 TRIMETHYLATION (H3K27ME3). HOWEVER, MACROPHAGES MIGRATED INTO INFLAMED TISSUES CAN TRANSDIFFERENTIATE, BUT IT IS UNKNOWN WHETHER INFLAMMATION ALTERS PCG-DEPENDENT SILENCING. HERE WE SHOW THAT THE JMJC-DOMAIN PROTEIN JMJD3 IS A H3K27ME DEMETHYLASE EXPRESSED IN MACROPHAGES IN RESPONSE TO BACTERIAL PRODUCTS AND INFLAMMATORY CYTOKINES. JMJD3 BINDS PCG TARGET GENES AND REGULATES THEIR H3K27ME3 LEVELS AND TRANSCRIPTIONAL ACTIVITY. THE DISCOVERY OF AN INDUCIBLE ENZYME THAT ERASES A HISTONE MARK CONTROLLING DIFFERENTIATION AND CELL IDENTITY PROVIDES A LINK BETWEEN INFLAMMATION AND REPROGRAMMING OF THE EPIGENOME, WHICH COULD BE THE BASIS FOR MACROPHAGE PLASTICITY AND MIGHT EXPLAIN THE DIFFERENTIATION ABNORMALITIES IN CHRONIC INFLAMMATION. 2007 5 4727 30 NOTABLE ROLES OF EZH2 AND DNMT1 IN EPIGENETIC DORMANCY OF THE SHP1 GENE DURING THE PROGRESSION OF CHRONIC MYELOID LEUKAEMIA. TUMOR DEVELOPMENT IS ASSOCIATED WITH THE METHYLATION OF CYTOSINE-GUANINE (CPG) ISLANDS. THE OCCURRENCE OF METHYLATION REQUIRES SEVERAL FACTORS, SUCH AS DNA METHYLATION SYSTEMS AND POLYCOMB GROUP (PCG) PROTEINS. AT PRESENT, NOVEL DRUGS ARE NEEDED FOR THE TREATMENT OF CHRONIC MYELOID LEUKAEMIA (CML), PARTICULARLY CONSIDERING THE CURRENT PROGNOSIS OF CML. THE METHYLATION STATUS OF THE SRC HOMOLOGY 2 DOMAIN-CONTAINING TYROSINE PHOSPHATASE 1 (SHP1) GENE, A NEGATIVE REGULATOR OF SIGNAL TRANSDUCTION, HAS BEEN IDENTIFIED AS BEING ALTERED IN NUMEROUS HAEMATOLOGICAL MALIGNANCIES. DNA METHYLTRANSFERASE 1 (DNMT1) AND THE PCG PROTEIN COMPLEX MEMBER ENHANCER OF ZESTE HOMOLOG 2 (EZH2) PARTICIPATE IN A NUMBER OF GENE METHYLATION PROCESSES. THE PRESENT STUDY INVESTIGATED THE METHYLATION STATUS OF THE SHP1 GENE IN CML, AND EXAMINED THE ASSOCIATION BETWEEN DNMT1 AND EZH2 ACTIVITY AND THE SHP1 GENE METHYLATION STATUS TO DEVELOP NOVEL STRATEGIES FOR THE TREATMENT OF CML. THE RESULTS REVEALED THAT SHP1 GENE METHYLATION STATUS WAS ALTERED DURING THE PROGRESSION OF CML. THESE DATA INDICATED THAT SHP1 GENE METHYLATION IS ASSOCIATED WITH THE PROGRESSION OF THIS DISEASE. THE ASSOCIATIONS OF DNMT1 AND EZH2 ACTIVITIES WITH THE METHYLATION STATUS OF THE SHP1 GENE WERE ADDITIONALLY INVESTIGATED VIA CHROMATIN IMMUNOPRECIPITATION. DNMT1 AND EZH2 WERE REVEALED TO BE BOUND TO THE PROMOTER REGION OF THE SHP1 GENE, AND WERE INVOLVED IN THE PROCESS OF SHP1 METHYLATION. FURTHERMORE, DNMT1 AND EZH2 WERE ASSOCIATED WITH DISEASE PROGRESSION. THUS, THE FINDINGS OF THE PRESENT STUDY SUGGEST A NEW TARGET FOR THE TREATMENT OF CML, PARTICULARLY FOR FUTURE DRUG DEVELOPMENT. 2017 6 3865 36 JAK2 REGULATES MISMATCH REPAIR PROTEIN-MEDIATED EPIGENETIC ALTERATIONS IN RESPONSE TO OXIDATIVE DAMAGE. AT SITES OF CHRONIC INFLAMMATION EPITHELIAL CELLS UNDERGO ABERRANT DNA METHYLATION THAT CONTRIBUTES TO TUMORIGENESIS. INFLAMMATION IS ASSOCIATED WITH AN INCREASE IN REACTIVE OXYGEN SPECIES (ROS) THAT CAUSE OXIDATIVE DNA DAMAGE, WHICH HAS ALSO BEEN LINKED TO EPIGENETIC ALTERATIONS. WE PREVIOUSLY DEMONSTRATED THAT IN RESPONSE TO ROS, MISMATCH REPAIR PROTEINS MSH2 AND MSH6 RECRUIT EPIGENETIC SILENCING PROTEINS DNA METHYLTRANSFERASE 1 (DNMT1) AND POLYCOMB REPRESSIVE COMPLEX 2 (PRC2) MEMBERS TO SITES OF DNA DAMAGE, RESULTING IN TRANSCRIPTIONAL REPRESSION OF TUMOR SUPPRESSOR GENES (TSGS). HOWEVER, IT WAS UNCLEAR WHAT SIGNAL IS UNIQUE TO ROS THAT RESULTS IN THE CHROMATIN BINDING OF MSH2 AND MSH6. HEREIN, WE DEMONSTRATE THAT IN RESPONSE TO HYDROGEN PEROXIDE (H(2) O(2) ), JAK2 LOCALIZES TO THE NUCLEUS AND INTERACTS WITH MSH2 AND MSH6. INHIBITION OR KNOCKDOWN OF JAK2 REDUCES THE H(2) O(2) -INDUCED CHROMATIN INTERACTION OF MSH2, MSH6, DNMT1, AND PRC2 MEMBERS, REDUCES H(2) O(2) -INDUCED GLOBAL INCREASE IN TRIMETHYLATION OF LYSINE 27 OF HISTONE H3 (H3K27ME3), AND ABROGATES OXIDATIVE DAMAGE-INDUCED TRANSCRIPTIONAL REPRESSION OF CANDIDATE TSGS. MOREOVER, JAK2 MRNA EXPRESSION IS ASSOCIATED WITH CPG ISLAND METHYLATOR PHENOTYPE (CIMP) STATUS IN HUMAN COLORECTAL CANCER. OUR FINDINGS PROVIDE NOVEL INSIGHT INTO THE CONNECTION BETWEEN KINASE ACTIVATION AND EPIGENETIC ALTERATIONS DURING OXIDATIVE DAMAGE AND INFLAMMATION. ENVIRON. MOL. MUTAGEN. 60:308-319, 2019. (C) 2018 WILEY PERIODICALS, INC. 2019 7 5101 35 POLYCOMB FACTOR PHF19 CONTROLS CELL GROWTH AND DIFFERENTIATION TOWARD ERYTHROID PATHWAY IN CHRONIC MYELOID LEUKEMIA CELLS. POLYCOMB GROUP (PCG) OF PROTEINS ARE A GROUP OF HIGHLY CONSERVED EPIGENETIC REGULATORS INVOLVED IN MANY BIOLOGICAL FUNCTIONS, SUCH AS EMBRYONIC DEVELOPMENT, CELL PROLIFERATION, AND ADULT STEM CELL DETERMINATION. PHD FINGER PROTEIN 19 (PHF19) IS AN ASSOCIATED FACTOR OF POLYCOMB REPRESSOR COMPLEX 2 (PRC2), OFTEN UPREGULATED IN HUMAN CANCERS. IN PARTICULAR, MYELOID LEUKEMIA CELL LINES SHOW INCREASED LEVELS OF PHF19, YET LITTLE IS KNOWN ABOUT ITS FUNCTION. HERE, WE HAVE CHARACTERIZED THE ROLE OF PHF19 IN MYELOID LEUKEMIA CELLS. WE DEMONSTRATED THAT PHF19 DEPLETION DECREASES CELL PROLIFERATION AND PROMOTES CHRONIC MYELOID LEUKEMIA (CML) DIFFERENTIATION. MECHANISTICALLY, WE HAVE SHOWN HOW PHF19 REGULATES THE PROLIFERATION OF CML THROUGH A DIRECT REGULATION OF THE CELL CYCLE INHIBITOR P21. FURTHERMORE, WE OBSERVED THAT MTF2, A PHF19 HOMOLOG, PARTIALLY COMPENSATES FOR PHF19 DEPLETION IN A SUBSET OF TARGET GENES, INSTRUCTING SPECIFIC ERYTHROID DIFFERENTIATION. TAKEN TOGETHER, OUR RESULTS SHOW THAT PHF19 IS A KEY TRANSCRIPTIONAL REGULATOR FOR CELL FATE DETERMINATION AND COULD BE A POTENTIAL THERAPEUTIC TARGET FOR MYELOID LEUKEMIA TREATMENT. 2021 8 912 21 CHRONIC EXPOSURE TO WATER POLLUTANT TRICHLOROETHYLENE INCREASED EPIGENETIC DRIFT IN CD4(+) T CELLS. AIM: AUTOIMMUNE DISEASE AND CD4(+) T-CELL ALTERATIONS ARE INDUCED IN MICE EXPOSED TO THE WATER POLLUTANT TRICHLOROETHYLENE (TCE). WE EXAMINED HERE WHETHER TCE ALTERED GENE-SPECIFIC DNA METHYLATION IN CD4(+) T CELLS AS A POSSIBLE MECHANISM OF IMMUNOTOXICITY. MATERIALS & METHODS: NAIVE AND EFFECTOR/MEMORY CD4(+) T CELLS FROM MICE EXPOSED TO TCE (0.5 MG/ML IN DRINKING WATER) FOR 40 WEEKS WERE EXAMINED BY BISULFITE NEXT-GENERATION DNA SEQUENCING. RESULTS: A PROBABILISTIC MODEL CALCULATED FROM MULTIPLE GENES SHOWED THAT TCE DECREASED METHYLATION CONTROL IN CD4(+) T CELLS. DATA FROM INDIVIDUAL GENES FITTED TO A QUADRATIC REGRESSION MODEL SHOWED THAT TCE INCREASED GENE-SPECIFIC METHYLATION VARIANCE IN BOTH CD4 SUBSETS. CONCLUSION: TCE INCREASED EPIGENETIC DRIFT OF SPECIFIC CPG SITES IN CD4(+) T CELLS. 2016 9 3175 32 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 10 3362 39 HISTONE LYSINE DEMETHYLASE KDM5B MAINTAINS CHRONIC MYELOID LEUKEMIA VIA MULTIPLE EPIGENETIC ACTIONS. THE HISTONE LYSINE DEMETHYLASE KDM5 FAMILY IS IMPLICATED IN NORMAL DEVELOPMENT AND STEM CELL MAINTENANCE BY EPIGENETIC MODULATION OF HISTONE METHYLATION STATUS. DEREGULATION OF THE KDM5 FAMILY HAS BEEN REPORTED IN VARIOUS TYPES OF CANCERS, INCLUDING HEMATOLOGICAL MALIGNANCIES. HOWEVER, THEIR TRANSCRIPTIONAL REGULATORY ROLES IN THE CONTEXT OF LEUKEMIA REMAIN UNCLEAR. HERE, WE FIND THAT KDM5B IS STRONGLY EXPRESSED IN NORMAL CD34(+) HEMATOPOIETIC STEM/PROGENITOR CELLS AND CHRONIC MYELOID LEUKEMIA (CML) CELLS. KNOCKDOWN OF KDM5B IN K562 CML CELLS REDUCED LEUKEMIA COLONY-FORMING POTENTIAL. TRANSCRIPTOME PROFILING OF KDM5B KNOCKDOWN K562 CELLS REVEALED THE DEREGULATION OF GENES INVOLVED IN MYELOID DIFFERENTIATION AND TOLL-LIKE RECEPTOR SIGNALING. THROUGH THE INTEGRATION OF TRANSCRIPTOME AND CHIP-SEQ PROFILING DATA, WE SHOW THAT KDM5B IS ENRICHED AT THE BINDING SITES OF THE GATA AND AP-1 TRANSCRIPTION FACTOR FAMILIES, SUGGESTING THEIR COLLABORATIONS IN THE REGULATION OF TRANSCRIPTION. EVEN THOUGH THE BINDING OF KDM5B SUBSTANTIALLY OVERLAPPED WITH H3K4ME1 OR H3K4ME3 MARK AT GENE PROMOTERS, ONLY A SMALL SUBSET OF THE KDM5B TARGETS SHOWED DIFFERENTIAL EXPRESSION IN ASSOCIATION WITH THE HISTONE DEMETHYLATION ACTIVITY. BY CHARACTERIZING THE INTERACTING PROTEINS IN K562 CELLS, WE DISCOVERED THAT KDM5B RECRUITS PROTEIN COMPLEXES INVOLVED IN THE MRNA PROCESSING MACHINERY, IMPLYING AN ALTERNATIVE EPIGENETIC ACTION MEDIATED BY KDM5B IN GENE REGULATION. OUR STUDY HIGHLIGHTS THE ONCOGENIC FUNCTIONS OF KDM5B IN CML CELLS AND SUGGESTS THAT KDM5B IS VITAL TO THE TRANSCRIPTIONAL REGULATION VIA MULTIPLE EPIGENETIC MECHANISMS. 2020 11 4497 45 MORPHINE LEADS TO GLOBAL GENOME CHANGES IN H3K27ME3 LEVELS VIA A POLYCOMB REPRESSIVE COMPLEX 2 (PRC2) SELF-REGULATORY MECHANISM IN MESCS. BACKGROUND: ENVIRONMENTALLY INDUCED EPIGENETIC CHANGES CAN LEAD TO HEALTH PROBLEMS OR DISEASE, BUT THE MECHANISMS INVOLVED REMAIN UNCLEAR. MORPHINE CAN PASS THROUGH THE PLACENTAL BARRIER LEADING TO ABNORMAL EMBRYO DEVELOPMENT. HOWEVER, THE MECHANISM BY WHICH MORPHINE CAUSES THESE EFFECTS AND HOW THEY SOMETIMES PERSIST INTO ADULTHOOD IS NOT WELL KNOWN. TO UNRAVEL THE MORPHINE-INDUCED CHROMATIN ALTERATIONS INVOLVED IN ABERRANT EMBRYO DEVELOPMENT, WE EXPLORED THE ROLE OF THE H3K27ME3/PRC2 REPRESSIVE COMPLEX IN GENE EXPRESSION AND ITS TRANSMISSION ACROSS CELLULAR GENERATIONS IN RESPONSE TO MORPHINE. RESULTS: USING MOUSE EMBRYONIC STEM CELLS AS A MODEL SYSTEM, WE FOUND THAT CHRONIC MORPHINE TREATMENT INDUCES A GLOBAL DOWNREGULATION OF THE HISTONE MODIFICATION H3K27ME3. CONVERSELY, CHIP-SEQ SHOWED A REMARKABLE INCREASE IN H3K27ME3 LEVELS AT SPECIFIC GENOMIC SITES, PARTICULARLY PROMOTERS, DISRUPTING SELECTIVE TARGET GENES RELATED TO EMBRYO DEVELOPMENT, CELL CYCLE AND METABOLISM. THROUGH A SELF-REGULATORY MECHANISM, MORPHINE DOWNREGULATED THE TRANSCRIPTION OF PRC2 COMPONENTS RESPONSIBLE FOR H3K27ME3 BY ENRICHING HIGH H3K27ME3 LEVELS AT THE PROMOTER REGION. DOWNREGULATION OF PRC2 COMPONENTS PERSISTED FOR AT LEAST 48 H (4 CELL CYCLES) FOLLOWING MORPHINE REMOVAL, THOUGH PROMOTER H3K27ME3 LEVELS RETURNED TO CONTROL LEVELS. CONCLUSIONS: MORPHINE INDUCES TARGETING OF THE PRC2 COMPLEX TO SELECTED PROMOTERS, INCLUDING THOSE OF PRC2 COMPONENTS, LEADING TO CHARACTERISTIC CHANGES IN GENE EXPRESSION AND A GLOBAL REDUCTION IN H3K27ME3. FOLLOWING MORPHINE REMOVAL, ENHANCED PROMOTER H3K27ME3 LEVELS REVERT TO NORMAL SOONER THAN GLOBAL H3K27ME3 OR PRC2 COMPONENT TRANSCRIPT LEVELS. WE SUGGEST THAT H3K27ME3 IS INVOLVED IN INITIATING MORPHINE-INDUCED CHANGES IN GENE EXPRESSION, BUT NOT IN THEIR MAINTENANCE. MODEL OF POLYCOMB REPRESSIVE COMPLEX 2 (PRC2) AND H3K27ME3 ALTERATIONS INDUCED BY CHRONIC MORPHINE EXPOSURE. MORPHINE INDUCES H3K27ME3 ENRICHMENT AT PROMOTERS OF GENES ENCODING CORE MEMBERS OF THE PRC2 COMPLEX AND IS ASSOCIATED WITH THEIR TRANSCRIPTIONAL DOWNREGULATION. 2020 12 1906 36 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 30 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 1268 34 CYTOPLASMATIC COMPARTMENTALIZATION BY BCR-ABL PROMOTES TET2 LOSS-OF-FUNCTION IN CHRONIC MYELOID LEUKEMIA. THE LOSS-OF-FUNCTION OF TEN-ELEVEN-TRANSLOCATION (TET) 2, A FE(2+) -OXOGLUTARATE-DEPENDENT DIOXYGENASE CATALYZING 5 METHYL CYTOSINE (5MC) CONVERSION INTO 5-HYDROXYMETHYLCYTOSINE (5HMC), CONTRIBUTES TO THE HEMATOPOIETIC TRANSFORMATION IN VIVO. THE AIM OF OUR STUDY WAS TO ELUCIDATE ITS ROLE IN THE PHENOTYPE OF CHRONIC MYELOID LEUKEMIA (CML), A MYELOPROLIFERATIVE DISEASE CAUSED BY THE BCR-ABL REARRANGED GENE. WE FIRST CONFIRMED TET2 INTERACTION WITH THE BCR-ABL PROTEIN PREDICTED BY A FOURIER-BASED BIOINFORMATIC METHOD. SUCH INTERACTION LED TO TET2 CYTOPLASMATIC COMPARTMENTALIZATION IN A COMPLEX TETHERED BY THE FUSION PROTEIN TYROSINE KINASE (TK) AND ENCOMPASSING THE FORKHEAD BOX O3A (FOXO3A) TRANSCRIPTION FACTOR. WE THEN FOCUSED THE IMPACT OF TET2 LOSS-OF-FUNCTION ON EPIGENETIC TRANSCRIPTIONAL REGULATION OF BCL2-INTERACTING MEDIATOR (BIM), A PRO-APOPTOTIC PROTEIN TRANSCRIPTIONALLY REGULATED BY FOXO3A. BIM DOWNREGULATION IS A CRITICAL COMPONENT OF CML PROGENITOR EXTENDED SURVIVAL AND IS ALSO INVOLVED IN THE DISEASE RESISTANCE TO IMATINIB (IM). HERE WE REPORTED THAT TET2 RELEASE FROM BCR-ABL PROTEIN FOLLOWING TK INHIBITION IN RESPONSE TO IM TRIGGERS A CHAIN OF EVENTS INCLUDING TET2 NUCLEAR TRANSLOCATION, RE-ACTIVATION OF ITS ENZYMATIC FUNCTION AT 5MC AND RECRUITMENT AT THE BIM PROMOTER FOLLOWED BY BIM TRANSCRIPTIONAL INDUCTION. 5HMC INCREMENT FOLLOWING TET2 RE-ACTIVATION WAS ASSOCIATED WITH THE REDUCTION OF HISTONE H3 TRI-METHYLATION AT LYSINE 9 (H3K9ME3), WHICH MAY CONTRIBUTE WITH DNA DE-METHYLATION REPORTED ELSEWHERE TO RECAST A PERMISSIVE EPIGENETIC "LANDSCAPE" FOR FOXO3A TRANSCRIPTIONAL ACTIVITY. 2012 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 5319 32 PTEN IS FUNDAMENTAL FOR ELIMINATION OF LEUKEMIA STEM CELLS MEDIATED BY GSK126 TARGETING EZH2 IN CHRONIC MYELOGENOUS LEUKEMIA. PURPOSE: LEUKEMIA STEM CELLS (LSCS) ARE AN IMPORTANT SOURCE OF TYROSINE KINASE INHIBITOR RESISTANCE AND DISEASE RELAPSE IN PATIENTS WITH CHRONIC MYELOGENOUS LEUKEMIA (CML). TARGETING LSCS MAY BE AN ATTRACTIVE STRATEGY TO OVERRIDE THIS THORNY PROBLEM. GIVEN THAT EZH2 WAS OVEREXPRESSED IN PRIMARY CML CD34(+) CELLS, OUR PURPOSE IN THIS STUDY WAS TO EVALUATE THE EFFECTS OF TARGETING EZH2 ON CML LSCS AND CLARIFY ITS UNDERLYING MECHANISM.EXPERIMENTAL DESIGN: HUMAN PRIMARY CML CD34(+) CELLS AND RETROVIRALLY BCR-ABL-DRIVEN CML MOUSE MODELS WERE EMPLOYED TO EVALUATE THE EFFECTS OF SUPPRESSION OF EZH2 BY GSK126- OR EZH2-SPECIFIC SHRNA IN VITRO AND IN VIVO RECRUITMENT OF EZH2 AND H3K27ME3 ON THE PROMOTER OF TUMOR-SUPPRESSOR GENE PTEN IN CML CELLS WAS MEASURED BY CHROMATIN IMMUNOPRECIPITATION ASSAY.RESULTS: OUR RESULTS SHOWED THAT PHARMACOLOGIC INHIBITION OF EZH2 BY GSK126 NOT ONLY ELICITED APOPTOSIS AND RESTRICTED CELL GROWTH IN CML BULK LEUKEMIA CELLS, BUT ALSO DECREASED LSCS IN CML CD34(+) CELLS WHILE SPARING THOSE FROM NORMAL BONE MARROW CD34(+) CELLS. SUPPRESSION OF EZH2 BY GSK126 OR SPECIFIC SHRNA PROLONGED SURVIVAL OF CML MICE AND REDUCED THE NUMBER OF LSCS IN MICE. EZH2 KNOCKDOWN RESULTED IN ELEVATION OF PTEN AND LED TO IMPAIRED RECRUITMENT OF EZH2 AND H3K27ME3 ON THE PROMOTER OF PTEN GENE. THE EFFECT OF EZH2 KNOCKDOWN IN THE CML MICE WAS AT LEAST PARTIALLY REVERSED BY PTEN KNOCKDOWN.CONCLUSIONS: THESE FINDINGS IMPROVE THE UNDERSTANDING OF THE EPIGENETIC REGULATION OF STEMNESS IN CML LSCS AND WARRANT CLINICAL TRIAL OF GSK126 IN REFRACTORY PATIENTS WITH CML. CLIN CANCER RES; 24(1); 145-57. (C)2017 AACR. 2018 17 1986 27 EPIGENETIC ALTERATIONS MAY REGULATE TEMPORARY REVERSAL OF CD4(+) T CELL ACTIVATION CAUSED BY TRICHLOROETHYLENE EXPOSURE. PREVIOUS STUDIES HAVE SHOWN THAT SHORT-TERM (4 WEEKS) OR CHRONIC (32 WEEKS) EXPOSURE TO TRICHLOROETHYLENE (TCE) IN DRINKING WATER OF FEMALE MRL+/+ MICE GENERATED CD4(+) T CELLS THAT SECRETED INCREASED LEVELS OF INTERFERON (IFN)-GAMMA AND EXPRESSED AN ACTIVATED (CD44(HI)CD62L(LO)) PHENOTYPE. IN CONTRAST, THE CURRENT STUDY OF SUBCHRONIC TCE EXPOSURE SHOWED THAT MIDWAY IN THE DISEASE PROCESS BOTH OF THESE PARAMETERS OF CD4(+) T CELL ACTIVATION WERE REVERSED. THIS PHASE OF THE DISEASE PROCESS MAY REPRESENT AN ATTEMPT BY THE BODY TO COUNTERACT THE INFLAMMATORY EFFECTS OF TCE. THE DECREASE IN CD4(+) T CELL PRODUCTION OF IFN-GAMMA FOLLOWING SUBCHRONIC TCE EXPOSURE COULD NOT BE ATTRIBUTED TO SKEWING TOWARD A TH2 OR TH17 PHENOTYPE OR TO AN INCREASE IN TREG CELLS. INSTEAD, THE SUPPRESSION CORRESPONDED TO ALTERATIONS IN MARKERS USED TO ASSESS DNA METHYLATION, NAMELY INCREASED EXPRESSION OF RETROTRANSPOSONS IAP (INTRACISTERNAL A PARTICLE) AND MUERV (MURINE ENDOGENOUS RETROVIRUS). ALSO OBSERVED WAS AN INCREASE IN THE EXPRESSION OF DNMT1 (DNA METHYLTRANSFERASE-1) AND DECREASED EXPRESSION OF SEVERAL GENES KNOWN TO BE DOWNREGULATED BY DNA METHYLATION, NAMELY IFNG, IL2, AND CDKN1A. CD4(+) T CELLS FROM A SECOND STUDY IN WHICH MRL+/+ MICE WERE TREATED FOR 17 WEEKS WITH TCE SHOWED A SIMILAR INCREASE IN IAP AND DECREASE IN CDKN1A. IN ADDITION, DNA COLLECTED FROM THE CD4(+) T CELLS IN THE SECOND STUDY SHOWED TCE-DECREASED GLOBAL DNA METHYLATION. THUS, THESE RESULTS DESCRIBED THE BIPHASIC NATURE OF TCE-INDUCED ALTERATIONS IN CD4(+) T CELL FUNCTION AND SUGGESTED THAT THESE CHANGES REPRESENTED POTENTIALLY REVERSIBLE ALTERATIONS IN EPIGENETIC PROCESSES. 2012 18 5675 30 SHIFTS IN PODOCYTE HISTONE H3K27ME3 REGULATE MOUSE AND HUMAN GLOMERULAR DISEASE. HISTONE PROTEIN MODIFICATIONS CONTROL FATE DETERMINATION DURING NORMAL DEVELOPMENT AND DEDIFFERENTIATION DURING DISEASE. HERE, WE SET OUT TO DETERMINE THE EXTENT TO WHICH DYNAMIC CHANGES TO HISTONES AFFECT THE DIFFERENTIATED PHENOTYPE OF ORDINARILY QUIESCENT ADULT GLOMERULAR PODOCYTES. TO DO THIS, WE EXAMINED THE CONSEQUENCES OF SHIFTING THE BALANCE OF THE REPRESSIVE HISTONE H3 LYSINE 27 TRIMETHYLATION (H3K27ME3) MARK IN PODOCYTES. ADRIAMYCIN NEPHROTOXICITY AND SUBTOTAL NEPHRECTOMY (SNX) STUDIES INDICATED THAT DELETION OF THE HISTONE METHYLATING ENZYME EZH2 FROM PODOCYTES DECREASED H3K27ME3 LEVELS AND SENSITIZED MICE TO GLOMERULAR DISEASE. H3K27ME3 WAS ENRICHED AT THE PROMOTER REGION OF THE NOTCH LIGAND JAG1 IN PODOCYTES, AND DEREPRESSION OF JAG1 BY EZH2 INHIBITION OR KNOCKDOWN FACILITATED PODOCYTE DEDIFFERENTIATION. CONVERSELY, INHIBITION OF THE JUMONJI C DOMAIN-CONTAINING DEMETHYLASES JMJD3 AND UTX INCREASED THE H3K27ME3 CONTENT OF PODOCYTES AND ATTENUATED GLOMERULAR DISEASE IN ADRIAMYCIN NEPHROTOXICITY, SNX, AND DIABETES. PODOCYTES IN GLOMERULI FROM HUMANS WITH FOCAL SEGMENTAL GLOMERULOSCLEROSIS OR DIABETIC NEPHROPATHY EXHIBITED DIMINISHED H3K27ME3 AND HEIGHTENED UTX CONTENT. ANALOGOUS TO HUMAN DISEASE, INHIBITION OF JMJD3 AND UTX ABATED NEPHROPATHY PROGRESSION IN MICE WITH ESTABLISHED GLOMERULAR INJURY AND REDUCED H3K27ME3 LEVELS. TOGETHER, THESE FINDINGS INDICATE THAT OSTENSIBLY STABLE CHROMATIN MODIFICATIONS CAN BE DYNAMICALLY REGULATED IN QUIESCENT CELLS AND THAT EPIGENETIC REPROGRAMMING CAN IMPROVE OUTCOMES IN GLOMERULAR DISEASE BY REPRESSING THE REACTIVATION OF DEVELOPMENTAL PATHWAYS. 2018 19 2825 41 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 20 6069 35 THE DIOXIN RECEPTOR IS SILENCED BY PROMOTER HYPERMETHYLATION IN HUMAN ACUTE LYMPHOBLASTIC LEUKEMIA THROUGH INHIBITION OF SP1 BINDING. THE TRANSCRIPTION FACTOR ARYL HYDROCARBON RECEPTOR (AHR) HAS RELEVANT FUNCTIONS IN CELL PROLIFERATION. INTERESTINGLY, THE AHR CAN EITHER PROMOTE OR INHIBIT PROLIFERATION DEPENDING ON THE CELL PHENOTYPE. ALTHOUGH RECENT DATA REVEAL POTENTIAL PATHWAYS FOR AHR SIGNALING IN CELL PROLIFERATION, THE MECHANISMS THAT REGULATE ITS ACTIVITY IN TUMOR CELLS REMAIN UNKNOWN. HERE, WE HAVE ANALYZED PROMOTER HYPERMETHYLATION AS A POTENTIAL MECHANISM CONTROLLING AHR EXPRESSION IN HUMAN TUMOR CELLS. AHR PROMOTER CPG METHYLATION WAS SPORADIC IN A PANEL OF 19 TUMOR CELL LINES EXCEPT FOR THE CHRONIC MYELOID LEUKEMIA (CML) K562 AND THE ACUTE LYMPHOBLASTIC LEUKEMIA (ALL) REH. WHEN COMPARED WITH NORMAL LYMPHOCYTES, REH HAD VERY LOW CONSTITUTIVE AHR EXPRESSION THAT COULD BE ATTRIBUTED TO PROMOTER HYPERMETHYLATION SINCE TREATMENT WITH THE DNA DEMETHYLATING AGENT 5-AZA-2'-DEOXYCITIDINE (AZA) SIGNIFICANTLY INCREASED AHR MRNA AND PROTEIN. THESE RESULTS IN LEUKEMIA-DERIVED CELL LINES WERE FURTHER CONFIRMED IN PRIMARY ALL, WHERE 33% OF THE PATIENTS (7/21) HAD AHR PROMOTER HYPERMETHYLATION. CHROMATIN IMMUNOPRECIPITATION (CHIP) SHOWED THAT METHYLATION IMPAIRED BINDING OF THE TRANSCRIPTION FACTOR SP1 TO THE AHR PROMOTER, THUS PROVIDING A MECHANISM FOR AHR DOWNREGULATION IN REH CELLS. THEREFORE, PROMOTER HYPERMETHYLATION REPRESENTS A NOVEL EPIGENETIC MECHANISM DOWNREGULATING AHR ACTIVITY IN HEMATOLOGICAL MALIGNANCIES SUCH AS ALL. 2006