1 3633 127 INCREASE IN HDAC9 SUPPRESSES MYOBLAST DIFFERENTIATION VIA EPIGENETIC REGULATION OF AUTOPHAGY IN HYPOXIA. EXTREMELY REDUCED OXYGEN (O(2)) LEVELS ARE DETRIMENTAL TO MYOGENIC DIFFERENTIATION AND MULTINUCLEATED MYOTUBE FORMATION, AND CHRONIC EXPOSURE TO HIGH-ALTITUDE HYPOXIA HAS BEEN REPORTED TO BE AN IMPORTANT FACTOR IN SKELETAL MUSCLE ATROPHY. HOWEVER, HOW CHRONIC HYPOXIA CAUSES MUSCLE DYSFUNCTION REMAINS UNKNOWN. IN THE PRESENT STUDY, WE FOUND THAT SEVERE HYPOXIA (1% O(2)) SIGNIFICANTLY INHIBITED THE FUNCTION OF C2C12 CELLS (FROM A MYOBLAST CELL LINE). IMPORTANTLY, THE IMPAIRMENT WAS CONTINUOUSLY MANIFESTED EVEN DURING CULTURE UNDER NORMOXIC CONDITIONS FOR SEVERAL PASSAGES. MECHANISTICALLY, WE REVEALED THAT HISTONE DEACETYLASES 9 (HDAC9), A MEMBER OF THE HISTONE DEACETYLASE FAMILY, WAS SIGNIFICANTLY INCREASED IN C2C12 CELLS UNDER HYPOXIC CONDITIONS, THEREBY INHIBITING INTRACELLULAR AUTOPHAGY LEVELS BY DIRECTLY BINDING TO THE PROMOTER REGIONS OF ATG7, BECLIN1, AND LC3. THIS PHENOMENON RESULTED IN THE SEQUENTIAL DEPHOSPHORYLATION OF GSK3BETA AND INACTIVATION OF THE CANONICAL WNT PATHWAY, IMPAIRING THE FUNCTION OF THE C2C12 CELLS. TAKEN TOGETHER, OUR RESULTS SUGGEST THAT HYPOXIA-INDUCED MYOBLAST DYSFUNCTION IS DUE TO ABERRANT EPIGENETIC REGULATION OF AUTOPHAGY, AND OUR EXPERIMENTAL EVIDENCE REVEALS THE POSSIBLE MOLECULAR PATHOGENESIS RESPONSIBLE FOR SOME MUSCLE DISEASES CAUSED BY CHRONIC HYPOXIA AND SUGGESTS A POTENTIAL THERAPEUTIC OPTION. 2019 2 1035 35 CLASS I HISTONE DEACETYLASE INHIBITION IMPROVES PANCREATITIS OUTCOME BY LIMITING LEUKOCYTE RECRUITMENT AND ACINAR-TO-DUCTAL METAPLASIA. BACKGROUND AND PURPOSE: PANCREATITIS IS A COMMON INFLAMMATION OF THE PANCREAS WITH RISING INCIDENCE IN MANY COUNTRIES. DESPITE IMPROVEMENTS IN DIAGNOSTIC TECHNIQUES, THE DISEASE IS ASSOCIATED WITH HIGH RISK OF SEVERE MORBIDITY AND MORTALITY AND THERE IS AN URGENT NEED FOR NEW THERAPEUTIC INTERVENTIONS. IN THIS STUDY, WE EVALUATED WHETHER HISTONE DEACETYLASES (HDACS), KEY EPIGENETIC REGULATORS OF GENE TRANSCRIPTION, ARE INVOLVED IN THE DEVELOPMENT OF THE DISEASE. EXPERIMENTAL APPROACH: WE ANALYSED HDAC REGULATION DURING CERULEIN-INDUCED ACUTE, CHRONIC AND AUTOIMMUNE PANCREATITIS USING DIFFERENT TRANSGENIC MOUSE MODELS. THE FUNCTIONAL RELEVANCE OF CLASS I HDACS WAS TESTED WITH THE SELECTIVE INHIBITOR MS-275 IN VIVO UPON PANCREATITIS INDUCTION AND IN VITRO IN ACTIVATED MACROPHAGES AND PRIMARY ACINAR CELL EXPLANTS. KEY RESULTS: HDAC EXPRESSION AND ACTIVITY WERE UP-REGULATED IN A TIME-DEPENDENT MANNER FOLLOWING INDUCTION OF PANCREATITIS, WITH THE HIGHEST ABUNDANCE OBSERVED FOR CLASS I HDACS. CLASS I HDAC INHIBITION DID NOT PREVENT THE INITIAL ACINAR CELL DAMAGE. HOWEVER, IT EFFECTIVELY REDUCED THE INFILTRATION OF INFLAMMATORY CELLS, INCLUDING MACROPHAGES AND T CELLS, IN BOTH ACUTE AND CHRONIC PHASES OF THE DISEASE, AND DIRECTLY DISRUPTED MACROPHAGE ACTIVATION. IN ADDITION, MS-275 TREATMENT REDUCED DNA DAMAGE IN ACINAR CELLS AND LIMITED ACINAR DE-DIFFERENTIATION INTO ACINAR-TO-DUCTAL METAPLASIA IN A CELL-AUTONOMOUS MANNER BY IMPEDING THE EGF RECEPTOR SIGNALLING AXIS. CONCLUSIONS AND IMPLICATIONS: THESE RESULTS DEMONSTRATE THAT CLASS I HDACS ARE CRITICALLY INVOLVED IN THE DEVELOPMENT OF ACUTE AND CHRONIC FORMS OF PANCREATITIS AND SUGGEST THAT BLOCKADE OF CLASS I HDAC ISOFORMS IS A PROMISING TARGET TO IMPROVE THE OUTCOME OF THE DISEASE. 2017 3 476 38 ARSENIC INDUCES FIBROGENIC CHANGES IN HUMAN KIDNEY EPITHELIAL CELLS POTENTIALLY THROUGH EPIGENETIC ALTERATIONS IN DNA METHYLATION. ARSENIC CONTAMINATION IS A SIGNIFICANT PUBLIC HEALTH ISSUE, AND KIDNEY IS ONE OF THE TARGET ORGAN FOR ARSENIC-INDUCED ADVERSE EFFECTS. RENAL FIBROSIS IS A WELL-KNOWN PATHOLOGICAL STAGE FREQUENTLY OBSERVED IN PROGRESSIVE CHRONIC KIDNEY DISEASE (CKD). EPIDEMIOLOGICAL STUDIES IMPLICATE ARSENIC EXPOSURE TO CKD, BUT THE ROLE OF ARSENIC IN KIDNEY FIBROSIS AND THE UNDERLYING MECHANISM IS STILL UNCLEAR. IT IS IN THIS CONTEXT THAT THE CURRENT STUDY EVALUATED THE EFFECTS OF LONG-TERM ARSENIC EXPOSURE ON THE CELLULAR RESPONSE IN MORPHOLOGY, AND MARKER GENES EXPRESSION WITH RESPECT TO FIBROSIS USING HUMAN KIDNEY 2 (HK-2) EPITHELIAL CELLS. RESULTS OF THIS STUDY REVEALED THAT IN ADDITION TO INCREASED GROWTH, HK-2 CELLS UNDERWENT PHENOTYPIC, BIOCHEMICAL AND MOLECULAR CHANGES INDICATIVE OF EPITHELIAL-MESENCHYMAL TRANSITION (EMT) IN RESPONSE TO THE EXPOSURE TO ARSENIC. MOST IMPORTANTLY, THE ARSENIC-EXPOSED CELLS ACQUIRED THE PATHOGENIC FEATURES OF FIBROSIS AS SUPPORTED BY INCREASED EXPRESSION OF MARKERS FOR FIBROSIS, SUCH AS COLLAGEN I, FIBRONECTIN, TRANSFORMING GROWTH FACTOR BETA, AND ALPHA-SMOOTH MUSCLE ACTIN. UPREGULATION OF FIBROSIS ASSOCIATED SIGNALING MOLECULES SUCH AS TISSUE INHIBITOR OF METALLOPROTEINASES-3 AND MATRIX METALLOPROTEINASE-2 AS WELL AS ACTIVATION OF AKT WAS ALSO OBSERVED. ADDITIONALLY, THE EXPRESSION OF EPIGENETIC GENES (DNA METHYLTRANSFERASES 3A AND 3B; METHYL-CPG BINDING DOMAIN 4) WAS INCREASED IN ARSENIC-EXPOSED CELLS. TREATMENT WITH DNA METHYLATION INHIBITOR 5-AZA-2'-DC REVERSED THE EMT PROPERTIES AND RESTORED THE LEVEL OF PHOSPHO-AKT. TOGETHER, THESE DATA FOR THE FIRST TIME SUGGEST THAT LONG-TERM EXPOSURE TO ARSENIC CAN INCREASE THE RISK OF KIDNEY FIBROSIS. ADDITIONALLY, OUR DATA SUGGEST THAT THE ARSENIC-INDUCED FIBROTIC CHANGES ARE, AT LEAST IN PART, MEDIATED BY DNA METHYLATION AND THEREFORE POTENTIALLY CAN BE REVERSED BY EPIGENETIC THERAPEUTICS. 2019 4 3935 40 LIVER-SPECIFIC KNOCKDOWN OF CLASS IIA HDACS HAS LIMITED EFFICACY ON GLUCOSE METABOLISM BUT ENTAILS SEVERE ORGAN SIDE EFFECTS IN MICE. HISTONE DEACETYLASES (HDACS) ARE IMPORTANT REGULATORS OF EPIGENETIC GENE MODIFICATION THAT ARE INVOLVED IN THE TRANSCRIPTIONAL CONTROL OF METABOLISM. IN PARTICULAR CLASS IIA HDACS HAVE BEEN SHOWN TO AFFECT HEPATIC GLUCONEOGENESIS AND PREVIOUS APPROACHES REVEALED THAT THEIR INHIBITION REDUCES BLOOD GLUCOSE IN TYPE 2 DIABETIC MICE. IN THE PRESENT STUDY, WE AIMED TO EVALUATE THE POTENTIAL OF CLASS IIA HDAC INHIBITION AS A THERAPEUTIC OPPORTUNITY FOR THE TREATMENT +OF METABOLIC DISEASES. FOR THAT, SIRNAS SELECTIVELY TARGETING HDAC4, 5 AND 7 WERE SELECTED AND USED TO ACHIEVE A COMBINATORIAL KNOCKDOWN OF THESE THREE CLASS IIA HDAC ISOFORMS. SUBSEQUENTLY, THE HEPATOCELLULAR EFFECTS AS WELL AS THE IMPACT ON GLUCOSE AND LIPID METABOLISM WERE ANALYZED IN VITRO AND IN VIVO. THE TRIPLE KNOCKDOWN RESULTED IN A STATISTICALLY SIGNIFICANT DECREASE OF GLUCONEOGENIC GENE EXPRESSION IN MURINE AND HUMAN HEPATOCYTE CELL MODELS. A SIMILAR HDAC-INDUCED DOWNREGULATION OF HEPATIC GLUCONEOGENESIS GENES COULD BE ACHIEVED IN MICE USING A LIVER-SPECIFIC LIPID NANOPARTICLE SIRNA FORMULATION. HOWEVER, THE EFFICACY ON WHOLE BODY GLUCOSE METABOLISM ASSESSED BY PYRUVATE-TOLERANCE TESTS WERE ONLY LIMITED AND DID NOT OUTWEIGH THE SAFETY FINDINGS OBSERVED BY HISTOPATHOLOGICAL ANALYSIS IN SPLEEN AND KIDNEY. MECHANISTICALLY, AFFYMETRIX GENE EXPRESSION STUDIES PROVIDE EVIDENCE THAT CLASS IIA HDACS DIRECTLY TARGET OTHER KEY FACTORS BEYOND THE DESCRIBED FORKHEAD BOX (FOXP) TRANSCRIPTION REGULATORS, SUCH AS HEPATOCYTE NUCLEAR FACTOR 4 ALPHA (HNF4A). DOWNSTREAM OF THESE FACTORS SEVERAL ADDITIONAL PATHWAYS WERE REGULATED NOT MERELY INCLUDING GLUCOSE AND LIPID METABOLISM AND TRANSPORT. IN CONCLUSION, THE LIVER-DIRECTED COMBINATORIAL KNOCKDOWN OF HDAC4, 5 AND 7 BY THERAPEUTIC SIRNAS AFFECTED MULTIPLE PATHWAYS IN VITRO, LEADING IN VIVO TO THE DOWNREGULATION OF GENES INVOLVED IN GLUCONEOGENESIS. HOWEVER, THE EFFECTS ON GENE EXPRESSION LEVEL WERE NOT PARALLELED BY A SIGNIFICANT REDUCTION OF GLUCONEOGENESIS IN MICE. COMBINED KNOCKDOWN OF HDAC ISOFORMS WAS ASSOCIATED WITH SEVERE ADVERSE EFFECTS IN VIVO, CHALLENGING THIS APPROACH AS A TREATMENT OPTION FOR CHRONIC METABOLIC DISORDERS LIKE TYPE 2 DIABETES. 2020 5 3342 32 HISTONE DEACETYLASE9 REPRESENTS THE EPIGENETIC PROMOTION OF M1 MACROPHAGE POLARIZATION AND INFLAMMATORY RESPONSE VIA TLR4 REGULATION. ATHEROSCLEROSIS IS A CHRONIC INFLAMMATORY RESPONSE MEDIATED BY VARIOUS FACTORS, WHERE EPIGENETIC REGULATION INVOLVING HISTONE DEACETYLATION IS ENVISAGED TO MODULATE THE EXPRESSION OF RELATED PROTEINS BY REGULATING THE BINDING OF TRANSCRIPTION FACTORS TO DNA, THEREBY INFLUENCING THE DEVELOPMENT OF ATHEROSCLEROSIS. THE MECHANISM OF ATHEROSCLEROSIS BY HISTONE DEACETYLATION IS PARTLY KNOWN; HENCE, THIS PROJECT AIMED AT INVESTIGATING THE ROLE OF HISTONE DEACETYLASE 9 (HDAC9) IN ATHEROSCLEROSIS. FOR THIS PURPOSE, SERUM WAS SEPARATED FROM BLOOD SAMPLES FOLLOWING CLOTTING AND CENTRIFUGATION FROM ATHEROSCLEROTIC AND HEALTHY PATIENTS (N = 40 EACH), AND THEN, VARIOUS TESTS WERE PERFORMED. THE RESULTS INDICATED THAT TOLL-LIKE RECEPTOR 4 (TLR4) WAS NOT ONLY POSITIVELY CORRELATED TO THE HDAC9 GENE, BUT WAS ALSO UPREGULATED IN ATHEROSCLEROSIS, WHERE IT WAS ALSO SIGNIFICANTLY UPREGULATED IN THE ATHEROSCLEROSIS CELL MODEL OF OXIDIZED LOW-DENSITY LIPOPROTEIN-INDUCED MACROPHAGES. CONVERSELY, THE TLR4 WAS SIGNIFICANTLY DOWNREGULATED IN INSTANCES OF LOSS OF HDAC9 FUNCTION, CEMENTING THE BRIDGING RELATIONSHIP BETWEEN HDAC9 AND MACROPHAGE POLARIZATION, WHERE THE HDAC9 WAS FOUND TO UPREGULATE M1 MACROPHAGE POLARIZATION WHICH TRANSLATED INTO THE RELEASE OF HIGHER CONTENT OF PROINFLAMMATORY CYTOKINES SUCH AS INTERLEUKIN-1BETA (IL-1BETA) AND TUMOR NECROSIS FACTOR-ALPHA (TNF-ALPHA), WHICH TEND TO SIGNIFICANTLY DECREASE FOLLOWING THE DELETION OF TLR4. HENCE, THIS STUDY REPORTS NOVEL RELATION BETWEEN EPIGENETIC CONTROL AND ATHEROSCLEROSIS, WHICH COULD PARTLY BE EXPLAINED BY HISTONE DEACETYLATION. 2022 6 6232 35 THE LONG NONCODING RNA MEG3 REGULATES MYOBLAST PLASTICITY AND MUSCLE REGENERATION THROUGH EPITHELIAL-MESENCHYMAL TRANSITION. FORMATION OF SKELETAL MUSCLE IS AMONG THE MOST STRIKING EXAMPLES OF CELLULAR PLASTICITY IN ANIMAL TISSUE DEVELOPMENT, AND WHILE MUSCLE PROGENITOR CELLS ARE REPROGRAMMED BY EPITHELIAL-MESENCHYMAL TRANSITION (EMT) TO MIGRATE DURING EMBRYONIC DEVELOPMENT, THE REGULATION OF EMT IN POST-NATAL MYOGENESIS REMAINS POORLY UNDERSTOOD. HERE, WE DEMONSTRATE THAT THE LONG NONCODING RNA (LNCRNA) MEG3 REGULATES EMT IN MYOBLAST DIFFERENTIATION AND SKELETAL MUSCLE REGENERATION. CHRONIC INHIBITION OF MEG3 IN C2C12 MYOBLASTS INDUCED EMT, AND SUPPRESSED CELL STATE TRANSITIONS REQUIRED FOR DIFFERENTIATION. FURTHERMORE, ADENOVIRAL MEG3 KNOCKDOWN COMPROMISED MUSCLE REGENERATION, WHICH WAS ACCOMPANIED BY ABNORMAL MESENCHYMAL GENE EXPRESSION AND INTERSTITIAL CELL PROLIFERATION. TRANSCRIPTOMIC AND PATHWAY ANALYSES OF MEG3-DEPLETED C2C12 MYOBLASTS AND INJURED SKELETAL MUSCLE REVEALED A SIGNIFICANT DYSREGULATION OF EMT-RELATED GENES, AND IDENTIFIED TGFBETA AS A KEY UPSTREAM REGULATOR. IMPORTANTLY, INHIBITION OF TGFBETAR1 AND ITS DOWNSTREAM EFFECTORS, AND THE EMT TRANSCRIPTION FACTOR SNAI2, RESTORED MANY ASPECTS OF MYOGENIC DIFFERENTIATION IN MEG3-DEPLETED MYOBLASTS IN VITRO WE FURTHER DEMONSTRATE THAT REDUCTION OF MEG3-DEPENDENT EZH2 ACTIVITY RESULTS IN EPIGENETIC ALTERATIONS ASSOCIATED WITH TGFBETA ACTIVATION. THUS, MEG3 REGULATES MYOBLAST IDENTITY TO FACILITATE PROGRESSION INTO DIFFERENTIATION. 2021 7 3341 38 HISTONE DEACETYLASE-2 IS INVOLVED IN STRESS-INDUCED COGNITIVE IMPAIRMENT VIA HISTONE DEACETYLATION AND PI3K/AKT SIGNALING PATHWAY MODIFICATION. EXPOSURE TO CHRONIC STRESS UPREGULATES BLOOD GLUCOCORTICOID LEVELS AND IMPAIRS COGNITION VIA DIVERSE EPIGENETIC MECHANISMS, SUCH AS HISTONE DEACETYLATION. HISTONE DEACETYLATION CAN LEAD TO TRANSCRIPTIONAL SILENCING OF MANY PROTEINS INVOLVED IN COGNITION AND MAY ALSO CAUSE LEARNING AND MEMORY DYSFUNCTION. HISTONE DEACETYLASE?2 (HDAC2) HAS BEEN DEMONSTRATED TO EPIGENETICALLY BLOCK COGNITION VIA A REDUCTION IN THE HISTONE ACETYLATION LEVEL; HOWEVER, IT IS UNKNOWN WHETHER HDAC2 IS INVOLVED IN THE COGNITIVE DECLINE INDUCED BY CHRONIC STRESS. TO THE BEST OF AUTHORS' KNOWLEDGE, THIS IS THE FIRST STUDY TO DEMONSTRATE THAT THE STRESS HORMONE CORTICOSTEROID UPREGULATE HDAC2 PROTEIN LEVELS IN NEURO?2A CELLS AND CAUSE CELL INJURIES. HDAC2 KNOCKDOWN RESULTED IN A SIGNIFICANT AMELIORATION OF THE PATHOLOGICAL CHANGES IN N2A CELLS VIA THE UPREGULATION OF HISTONE ACETYLATION AND MODIFICATIONS IN THE PHOSPHOINOSITIDE 3?KINASE/PROTEIN KINASE B SIGNALING PATHWAY. IN ADDITION, THE HDAC2 PROTEIN LEVELS WERE UPREGULATED IN 12?MONTH?OLD FEMALE C57BL/6J MICE UNDER CHRONIC STRESS IN VIVO. TAKEN TOGETHER, THESE FINDINGS SUGGESTED THAT HDAC2 MAY BE AN IMPORTANT NEGATIVE REGULATOR INVOLVED IN CHRONIC STRESS?INDUCED COGNITIVE IMPAIRMENT. 2017 8 2493 29 EPIGENETICS AND CHROMATIN REMODELING PLAY A ROLE IN LUNG DISEASE. EPIGENETICS IS DEFINED AS HERITABLE CHANGES THAT AFFECT GENE EXPRESSION WITHOUT ALTERING THE DNA SEQUENCE. EPIGENETIC REGULATION OF GENE EXPRESSION IS FACILITATED THROUGH DIFFERENT MECHANISMS SUCH AS DNA METHYLATION, HISTONE MODIFICATIONS AND RNA-ASSOCIATED SILENCING BY SMALL NON-CODING RNAS. ALL THESE MECHANISMS ARE CRUCIAL FOR NORMAL DEVELOPMENT, DIFFERENTIATION AND TISSUE-SPECIFIC GENE EXPRESSION. THESE THREE SYSTEMS INTERACT AND STABILIZE ONE ANOTHER AND CAN INITIATE AND SUSTAIN EPIGENETIC SILENCING, THUS DETERMINING HERITABLE CHANGES IN GENE EXPRESSION. HISTONE ACETYLATION REGULATES DIVERSE CELLULAR FUNCTIONS INCLUDING INFLAMMATORY GENE EXPRESSION, DNA REPAIR AND CELL PROLIFERATION. TRANSCRIPTIONAL COACTIVATORS POSSESS INTRINSIC HISTONE ACETYLTRANSFERASE ACTIVITY AND THIS ACTIVITY DRIVES INFLAMMATORY GENE EXPRESSION. ELEVEN CLASSICAL HISTONE DEACETYLASES (HDACS) ACT TO REGULATE THE EXPRESSION OF DISTINCT SUBSETS OF INFLAMMATORY/IMMUNE GENES. THUS, LOSS OF HDAC ACTIVITY OR THE PRESENCE OF HDAC INHIBITORS CAN FURTHER ENHANCE INFLAMMATORY GENE EXPRESSION BY PRODUCING A GENE-SPECIFIC CHANGE IN HAT ACTIVITY. FOR EXAMPLE, HDAC2 EXPRESSION AND ACTIVITY ARE REDUCED IN LUNG MACROPHAGES, BIOPSY SPECIMENS, AND BLOOD CELLS FROM PATIENTS WITH SEVERE ASTHMA AND SMOKING ASTHMATICS, AS WELL AS IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD). THIS MAY ACCOUNT, AT LEAST IN PART, FOR THE ENHANCED INFLAMMATION AND REDUCED STEROID RESPONSIVENESS SEEN IN THESE PATIENTS. OTHER PROTEINS, PARTICULARLY TRANSCRIPTION FACTORS, ARE ALSO ACETYLATED AND ARE TARGETS FOR DEACETYLATION BY HDACS AND SIRTUINS, A RELATED FAMILY OF 7 PREDOMINANTLY PROTEIN DEACETYLASES. THUS THE ACETYLATION/DEACETYLATION STATUS OF NF-KAPPAB AND THE GLUCOCORTICOID RECEPTOR CAN ALSO AFFECT THE OVERALL EXPRESSION PATTERN OF INFLAMMATORY GENES AND REGULATE THE INFLAMMATORY RESPONSE. UNDERSTANDING AND TARGETING SPECIFIC ENZYMES INVOLVED IN THIS PROCESS MIGHT LEAD TO NEW THERAPEUTIC AGENTS, PARTICULARLY IN SITUATIONS IN WHICH CURRENT ANTI-INFLAMMATORY THERAPIES ARE SUBOPTIMAL. 2011 9 3720 32 INHIBITION OF CLASS I HISTONE DEACETYLASES ABROGATES TUMOR GROWTH FACTOR BETA EXPRESSION AND DEVELOPMENT OF FIBROSIS DURING CHRONIC PANCREATITIS. PANCREATIC FIBROSIS IS THE HALLMARK OF CHRONIC PANCREATITIS, A HIGHLY DEBILITATING DISEASE FOR WHICH THERE IS CURRENTLY NO CURE. THE KEY EVENT AT THE BASIS OF PANCREATIC FIBROSIS IS THE DEPOSITION OF EXTRACELLULAR MATRIX PROTEINS BY ACTIVATED PANCREATIC STELLATE CELLS (PSCS). TRANSFORMING GROWTH FACTOR BETA (TGFBETA) IS A POTENT PROFIBROTIC FACTOR IN THE PANCREAS AS IT PROMOTES THE ACTIVATION OF PSC; THUS, PHARMACOLOGIC INTERVENTIONS THAT EFFECTIVELY REDUCE TGFBETA EXPRESSION HARBOR CONSIDERABLE THERAPEUTIC POTENTIAL IN THE TREATMENT OF CHRONIC PANCREATITIS. IN THIS STUDY, WE INVESTIGATED WHETHER TGFBETA EXPRESSION IS REDUCED BY PHARMACOLOGIC INHIBITION OF THE EPIGENETIC MODIFIERS HISTONE DEACETYLASES (HDACS). TO ADDRESS THIS AIM, CHRONIC PANCREATITIS WAS INDUCED IN C57BL/6 MICE WITH SERIAL INJECTIONS OF CERULEIN, AND THE SELECTIVE CLASS 1 HDAC INHIBITOR MS-275 WAS ADMINISTERED IN VIVO IN A PREVENTIVE AND THERAPEUTIC MANNER. BOTH MS-275 REGIMENS POTENTLY REDUCED DEPOSITION OF EXTRACELLULAR MATRIX AND DEVELOPMENT OF FIBROSIS IN THE PANCREAS AFTER 4 WEEKS OF CHRONIC PANCREATITIS. REDUCED PANCREATIC FIBROSIS WAS CONCOMITANT WITH LOWER EXPRESSION OF PANCREATIC TGFBETA AND CONSEQUENT REDUCED PSC ACTIVATION. IN SEARCH OF THE CELL TYPES TARGETED BY THE INHIBITOR, WE FOUND THAT MS-275 TREATMENT ABROGATED THE EXPRESSION OF TGFBETA IN ACINAR CELLS STIMULATED BY CERULEIN TREATMENT. OUR STUDY DEMONSTRATES THAT MS-275 IS AN EFFECTIVE ANTIFIBROTIC AGENT IN THE CONTEXT OF EXPERIMENTAL CHRONIC PANCREATITIS AND THUS MAY CONSTITUTE A VALID THERAPEUTIC INTERVENTION FOR THIS SEVERE DISEASE. 2018 10 4702 37 NICOTINE-INDUCED OXIDATIVE STRESS CONTRIBUTES TO EMT AND STEMNESS DURING NEOPLASTIC TRANSFORMATION THROUGH EPIGENETIC MODIFICATIONS IN HUMAN KIDNEY EPITHELIAL CELLS. NICOTINE IS A COMPONENT OF CIGARETTE SMOKE AND MOUNTING EVIDENCE SUGGESTS TOXICITY AND CARCINOGENICITY OF TOBACCO SMOKE IN KIDNEY. CARCINOGENICITY OF NICOTINE ITSELF IN KIDNEY AND THE UNDERLYING MOLECULAR MECHANISMS ARE NOT WELL-UNDERSTOOD. HENCE, THE OBJECTIVE OF THIS STUDY WAS TO DETERMINE THE CARCINOGENIC EFFECTS OF CHRONIC NICOTINE EXPOSURE IN HK-2 HUMAN KIDNEY EPITHELIAL CELLS. THE EFFECTS OF NICOTINE EXPOSURE ON THE EXPRESSION OF GENES FOR CELLULAR REPROGRAMMING, REDOX STATUS, AND GROWTH SIGNALING PATHWAYS WERE ALSO EVALUATED TO UNDERSTAND THE MOLECULAR MECHANISMS. RESULTS REVEALED THAT CHRONIC EXPOSURE TO NICOTINE INDUCED GROWTH AND NEOPLASTIC TRANSFORMATION IN HK-2 CELLS. INCREASED LEVELS OF INTRACELLULAR REACTIVE OXYGEN SPECIES (ROS), ACQUIRED STEM CELL-LIKE SPHERE FORMATION, AND EPITHELIAL-MESENCHYMAL-TRANSITION (EMT) CHANGES WERE OBSERVED IN NICOTINE EXPOSED CELLS. TREATMENT WITH ANTIOXIDANT N-ACETYL CYSTEINE (NAC) RESULTED IN ABROGATION OF EMT AND STEMNESS IN HK-2 CELLS, INDICATING THE ROLE OF NICOTINE-INDUCED ROS IN THESE MORPHOLOGICAL CHANGES. THE RESULT ALSO SUGGESTS THAT ROS CONTROLS THE STEMNESS THROUGH REGULATION OF AKT PATHWAY DURING EARLY STAGES OF CARCINOGENESIS. ADDITIONALLY, THE EXPRESSION OF EPIGENETIC REGULATORY GENES WAS ALTERED IN NICOTINE-EXPOSED CELLS AND THE CHANGES WERE REVERSED BY NAC. THE EPIGENETIC THERAPEUTICS 5-AZA-2'-DEOXYCYTIDINE AND TRICHOSTATIN A ALSO ABROGATED THE STEMNESS. THIS SUGGESTS THE NICOTINE-INDUCED OXIDATIVE STRESS CAUSED EPIGENETIC ALTERATIONS CONTRIBUTING TO STEMNESS DURING NEOPLASTIC TRANSFORMATION. TO OUR KNOWLEDGE, THIS IS THE FIRST REPORT SHOWING THE ROS-MEDIATED EPIGENETIC MODIFICATIONS AS THE UNDERLYING MECHANISM FOR CARCINOGENICITY OF NICOTINE IN HUMAN KIDNEY EPITHELIAL CELLS. THIS STUDY FURTHER SUGGESTS THE POTENTIAL OF EPIGENETIC THERAPEUTICS FOR PHARMACOLOGICAL INTERVENTION IN NICOTINE-INDUCED KIDNEY CANCER. 2019 11 2380 25 EPIGENETIC REGULATION OF WNT SIGNALING IN CHRONIC LYMPHOCYTIC LEUKEMIA. CERTAIN WNT AND WNT NETWORK TARGET GENES ARE EXPRESSED AT HIGHER OR LOWER LEVELS IN CHRONIC LYMPHOCYTIC LEUKEMIA COMPARED WITH NORMAL B-CELLS. THIS INCLUDES UPREGULATION OF NUCLEAR COMPLEX GENES, AS WELL AS GENES FOR CYTOPLASMIC PROTEINS AND WNT LIGANDS AND THEIR COGNATE RECEPTORS. IN ADDITION, EPIGENETIC SILENCING OF SEVERAL NEGATIVE REGULATORS OF THE WNT PATHWAY HAVE BEEN IDENTIFIED. THE BALANCE BETWEEN EPIGENETIC DOWNREGULATION OF NEGATIVE EFFECTOR GENES AND INCREASED EXPRESSION OF POSITIVE EFFECTOR GENES DEMONSTRATE THAT THE EPIGENETIC DOWNREGULATION OF WNT ANTAGONISTS IS ONE MECHANISM, PERHAPS THE MAIN MECHANISM, THAT IS PERMISSIVE TO ACTIVE WNT SIGNALING IN CHRONIC LYMPHOCYTIC LEUKEMIA. MOREOVER, CONSTITUTIVE ACTIVATION OF THE WNT NETWORK AND TARGET GENES IS LIKELY TO IMPACT ON ADDITIONAL INTERACTING SIGNALING PATHWAYS. BASED ON PUBLISHED STUDIES, WE PROPOSE A MODEL OF WNT SIGNALING THAT INVOLVES MAINLY PERMISSIVE EXPRESSION, AND SOMETIMES OVEREXPRESSION, OF POSITIVE EFFECTORS AND DOWNREGULATION OF NEGATIVE REGULATORS IN THE NETWORK. IN THIS MODEL, DNA METHYLATION, HISTONE MODIFICATIONS AND ALTERED EXPRESSION OF MICRORNA MOLECULES INTERACT TO ALLOW CONTINUOUS WNT SIGNALING. 2010 12 4768 30 NUCLEAR EFFECTS OF ETHANOL-INDUCED PROTEASOME INHIBITION IN LIVER CELLS. ALCOHOL INGESTION CAUSES ALTERATION IN SEVERAL CELLULAR MECHANISMS, AND LEADS TO INFLAMMATION, APOPTOSIS, IMMUNOLOGICAL RESPONSE DEFECTS, AND FIBROSIS. THESE PHENOMENA ARE ASSOCIATED WITH SIGNIFICANT CHANGES IN THE EPIGENETIC MECHANISMS, AND SUBSEQUENTLY, TO LIVER CELL MEMORY. THE UBIQUITIN-PROTEASOME PATHWAY IS ONE OF THE VITAL PATHWAYS IN THE CELL THAT BECOMES DYSFUNCTIONAL AS A RESULT OF CHRONIC ETHANOL CONSUMPTION. INHIBITION OF THE PROTEASOME ACTIVITY IN THE NUCLEUS CAUSES CHANGES IN THE TURNOVER OF TRANSCRIPTIONAL FACTORS, HISTONE MODIFYING ENZYMES, AND THEREFORE, AFFECTS EPIGENETIC MECHANISMS. ALCOHOL CONSUMPTION HAS BEEN ASSOCIATED WITH AN INCREASE IN HISTONE ACETYLATION AND A DECREASE IN HISTONE METHYLATION, WHICH LEADS TO GENE EXPRESSION CHANGES. DNA AND HISTONE MODIFICATIONS THAT RESULT FROM ETHANOL-INDUCED PROTEASOME INHIBITION ARE KEY PLAYERS IN REGULATING GENE EXPRESSION, ESPECIALLY GENES INVOLVED IN THE CELL CYCLE, IMMUNOLOGICAL RESPONSES, AND METABOLISM OF ETHANOL. THE PRESENT REVIEW HIGHLIGHTS THE CONSEQUENCES OF ETHANOL-INDUCED PROTEASOME INHIBITION IN THE NUCLEUS OF LIVER CELLS THAT ARE CHRONICALLY EXPOSED TO ETHANOL. 2009 13 1442 36 DIFFERENTIAL RESPONSE OF HUMAN HEPATOCYTE CHROMATIN TO HDAC INHIBITORS AS A FUNCTION OF MICROENVIRONMENTAL GLUCOSE LEVEL. DIABETES IS A COMPLEX MULTIFACTORIAL DISORDER CHARACTERIZED BY CHRONIC HYPERGLYCEMIA DUE TO IMPAIRED INSULIN SECRETION. RECENT OBSERVATIONS SUGGEST THAT THE COMPLEXITY OF THE DISEASE CANNOT BE ENTIRELY ACCOUNTED FOR GENETIC PREDISPOSITION AND A COMPELLING ARGUMENT FOR AN EPIGENETIC COMPONENT IS RAPIDLY EMERGING. THE USE OF HISTONE DEACETYLASE INHIBITOR (HDACI) IN CLINICAL SETTING IS AN EMERGING AREA OF INVESTIGATION. IN THIS STUDY, WE HAVE AIMED TO UNDERSTAND AND COMPARE THE RESPONSE OF HEPATOCYTE CHROMATIN TO VALPROIC ACID (VPA) AND TRICHOSTATIN A (TSA) TREATMENTS UNDER NORMOGLYCEMIC OR HYPERGLYCEMIC CONDITIONS TO EXPAND OUR KNOWLEDGE ABOUT THE CONSEQUENCES OF HDACI TREATMENT IN A DIABETES CELL MODEL. UNDER NORMOGLYCEMIC CONDITIONS, THESE TREATMENTS PROMOTED CHROMATIN REMODELING, AS ASSESSED BY IMAGE ANALYSIS AND H3K9AC AND H3K9ME2 ABUNDANCE. SIMULTANEOUSLY, H3K9AC MARKS SHIFTED TO THE NUCLEAR PERIPHERY ACCOMPANIED BY HP1 DISSOCIATION FROM THE HETEROCHROMATIN AND A G1 CELL CYCLE ARREST. MORE STRIKING CHANGES IN THE CELL CYCLE PROGRESSION AND MITOTIC RATIOS REQUIRED DRASTIC TREATMENT. UNDER HYPERGLYCEMIC CONDITIONS, HIGH GLUCOSE PER SE PROMOTED CHROMATIN CHANGES SIMILAR TO THOSE PROMOTED BY VPA AND TSA. NONETHELESS, THESE RESULTS WERE NOT INTENSIFIED IN CELLS TREATED WITH HDACIS UNDER HYPERGLYCEMIC CONDITIONS. DESPITE THE ABSENCE OF MORPHOLOGICAL CHANGES BEING PROMOTED, HDACI TREATMENT SEEMS TO CONFER A PHYSIOLOGICAL MEANING, AMELIORATING THE CELLULAR HYPERGLYCEMIC STATE THROUGH REDUCTION OF GLUCOSE PRODUCTION. THESE OBSERVATIONS ALLOW US TO CONCLUDE THAT THE GLUCOSE LEVEL TO WHICH THE HEPATOCYTES ARE SUBJECTED AFFECTS HOW CHROMATIN RESPONDS TO HDACI AND THEIR ACTION UNDER HIGH-GLUCOSE ENVIRONMENT MIGHT NOT REFLECT ON CHROMATIN REMODELING. J. CELL. PHYSIOL. 231: 2257-2265, 2016. (C) 2016 WILEY PERIODICALS, INC. 2016 14 141 35 ABERRANT DNA METHYLATION OF MTOR PATHWAY GENES PROMOTES INFLAMMATORY ACTIVATION OF IMMUNE CELLS IN DIABETIC KIDNEY DISEASE. DNA METHYLATION HAS BEEN IMPLICATED IN THE PATHOGENESIS OF DIABETIC KIDNEY DISEASE (DKD), BUT THE UNDERLYING MECHANISMS REMAIN UNCLEAR. IN THIS STUDY, WE TESTED THE HYPOTHESIS THAT ABERRANT DNA METHYLATION IN PERIPHERAL IMMUNE CELLS CONTRIBUTES TO DKD PROGRESSION. WE SHOWED THAT LEVELS OF DNA METHYLTRANSFERASE 1 (DNMT1), A KEY ENZYME FOR DNA METHYLATION, WERE INCREASED ALONG WITH INFLAMMATORY ACTIVITY OF PERIPHERAL BLOOD MONONUCLEAR CELLS IN DKD PATIENTS. INHIBITION OF DNMT1 WITH 5-AZA-2'-DEOXYCYTIDINE (5-AZA) MARKEDLY INCREASED THE PROPORTION OF CD4(+)CD25(+) REGULATORY T CELLS IN PERIPHERAL BLOOD MONONUCLEAR CELLS IN CULTURE AND IN DIABETIC ANIMALS. ADOPTIVE TRANSFER OF IMMUNE CELLS FROM 5-AZA-TREATED ANIMALS SHOWED BENEFICIAL EFFECTS ON THE HOST IMMUNE SYSTEM, RESULTING IN A SIGNIFICANT IMPROVEMENT OF DKD. USING GENOME-WIDE DNA METHYLATION ASSAYS, WE IDENTIFIED THE DIFFERENTIALLY METHYLATED CYTOSINES IN THE PROMOTER REGIONS OF MAMMALIAN TARGET OF RAPAMYCIN (MTOR) REGULATORS IN PERIPHERAL BLOOD MONONUCLEAR CELLS OF DIABETIC PATIENTS. FURTHER, MRNA ARRAYS CONFIRMED THE CONSISTENT INDUCTION OF GENES EXPRESSED IN THE MTOR PATHWAY. IMPORTANTLY, DOWN-REGULATION OF DNMT1 EXPRESSION VIA RNA INTERFERENCE RESULTED IN PROMINENT CYTOSINE DEMETHYLATION OF MTOR NEGATIVE REGULATORS AND SUBSEQUENT DECREASE OF MTOR ACTIVITY. LASTLY, MODULATION OF MTOR RESULTED IN CHANGES IN THE EFFECT OF 5-AZA ON DIABETIC IMMUNE CELLS. THUS, UP-REGULATION OF DNMT1 IN DIABETIC IMMUNE CELLS INDUCES ABERRANT CYTOSINE METHYLATION OF THE UPSTREAM REGULATORS OF MTOR, LEADING TO PATHOGENIC ACTIVATION OF THE MTOR PATHWAY AND CONSEQUENT INFLAMMATION IN DIABETIC KIDNEYS. HENCE, THIS STUDY HIGHLIGHTS THERAPEUTIC POTENTIAL OF TARGETING EPIGENETIC EVENTS IN IMMUNE SYSTEM FOR TREATING DKD. 2019 15 3795 30 INTERLEUKIN-6 CONTRIBUTES TO GROWTH IN CHOLANGIOCARCINOMA CELLS BY ABERRANT PROMOTER METHYLATION AND GENE EXPRESSION. THE ASSOCIATION BETWEEN CHRONIC INFLAMMATION AND THE DEVELOPMENT AND PROGRESSION OF MALIGNANCY IS EXEMPLIFIED IN THE BILIARY TRACT WHERE PERSISTENT INFLAMMATION STRONGLY PREDISPOSES TO CHOLANGIOCARCINOMA. THE INFLAMMATORY CYTOKINE INTERLEUKIN-6 (IL-6) ENHANCES TUMOR GROWTH IN CHOLANGIOCARCINOMA BY ALTERED GENE EXPRESSION VIA AUTOCRINE MECHANISMS. IL-6 CAN REGULATE THE ACTIVITY OF DNA METHYLTRANSFERASES, AND MOREOVER, ABERRANT DNA METHYLATION CAN CONTRIBUTE TO CARCINOGENESIS. WE THEREFORE INVESTIGATED THE EFFECT OF CHRONIC EXPOSURE TO IL-6 ON METHYLATION-DEPENDENT GENE EXPRESSION AND TRANSFORMED CELL GROWTH IN HUMAN CHOLANGIOCARCINOMA. THE RELATIONSHIP BETWEEN AUTOCRINE IL-6 PATHWAYS, DNA METHYLATION, AND TRANSFORMED CELL GROWTH WAS ASSESSED USING MALIGNANT CHOLANGIOCYTES STABLY TRANSFECTED TO OVEREXPRESS IL-6. TREATMENT WITH THE DNA METHYLATION INHIBITOR 5-AZA-2'-DEOXYCYTIDINE DECREASED CELL PROLIFERATION, GROWTH IN SOFT AGAR, AND METHYLCYTOSINE CONTENT OF MALIGNANT CHOLANGIOCYTES. HOWEVER, THIS EFFECT WAS NOT OBSERVED IN IL-6-OVEREXPRESSING CELLS. IL-6 OVEREXPRESSION RESULTED IN THE ALTERED EXPRESSION AND PROMOTER METHYLATION OF SEVERAL GENES, INCLUDING THE EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR). EGFR PROMOTER METHYLATION WAS DECREASED AND GENE AND PROTEIN EXPRESSION WAS INCREASED BY IL-6. THUS, EPIGENETIC REGULATION OF GENE EXPRESSION BY IL-6 CAN CONTRIBUTE TO TUMOR PROGRESSION BY ALTERING PROMOTER METHYLATION AND GENE EXPRESSION OF GROWTH-REGULATORY PATHWAYS, SUCH AS THOSE INVOLVING EGFR. MOREOVER, ENHANCED IL-6 EXPRESSION MAY DECREASE THE SENSITIVITY OF TUMOR CELLS TO THERAPEUTIC TREATMENTS USING METHYLATION INHIBITORS. THESE OBSERVATIONS HAVE IMPORTANT IMPLICATIONS FOR CANCER TREATMENT AND PROVIDE A MECHANISM BY WHICH PERSISTENT CYTOKINE STIMULATION CAN PROMOTE TUMOR GROWTH. 2006 16 3348 34 HISTONE DEACETYLASES MEET MICRORNA-ASSOCIATED MMP-9 EXPRESSION REGULATION IN GLUCOCORTICOID-SENSITIVE AND -RESISTANT CELL LINES. GLUCOCORTICOIDS ARE LARGELY USED IN THE TREATMENT OF INFLAMMATORY PATHOLOGIES AND/OR HEMATOLOGICAL MALIGNANCIES AND REGULATE THE EXPRESSION OF A VARIETY OF GENES INVOLVED IN INFLAMMATION OR METASTASIS SUCH AS MATRIX METALLOPROTEINASES (MMP). LONG-TERM EXPOSURE TO GLUCOCORTICOIDS CAN RESULT IN FAILURE OF RESPONSIVENESS, WHICH IS OFTEN ASSOCIATED WITH AN UNWANTED GENE EXPRESSION. EPIGENETIC MECHANISMS ARE INVOLVED IN GENE EXPRESSION MODULATED AFTER DEVELOPMENT OF GLUCOCORTICOID RESISTANCE BUT HOW THESE MECHANISMS TAKE PLACE MUST BE FURTHER STUDIED. THE EFFECTS OF HDAC INHIBITORS (HDACI) IN A CONTEXT OF GLUCOCORTICOID RESISTANCE ARE STILL NOT WELL UNDERSTOOD AND NEED TO BE FURTHER INVESTIGATED. WE HYPOTHESIZED THAT ACQUIRED GLUCOCORTICOID RESISTANCE ASSOCIATED TO HDACI COULD DISTURBS EPIGENETIC LANDSCAPE, ESPECIALLY MIR EXPRESSION, LEADING TO A MODULATION OF MMP-9 GENE EXPRESSION AND/OR PROTEIN SECRETION, DESCRIBED AS LARGELY INVOLVED IN BONE REMODELING AND TUMOR INVASION IN MULTIPLE MYELOMA. TO THIS AIM, WE USED SENSITIVE RPMI-8226 CELL LINE AND ITS DEXAMETHASONE- AND METHYLPREDNISOLONE-RESISTANT DERIVATIVES. THE RESISTANT CELL LINES DISPLAYED AN 'OPEN CHROMATIN' AND AN MMP-9 OVEREXPRESSION COMPARATIVELY TO THE SENSITIVE CELL LINE. HDACI TREATMENT WITH MS-275 INCREASED EVEN MORE MMP-9 OVEREXPRESSION NOT ONLY AT AN MRNA LEVEL BUT ALSO AT THE PROTEIN LEVEL. WE SHOWED THAT MMP-9 EXPRESSION REGULATION WAS NOT DIRECTLY LINKED WITH HAT/HDAC BALANCE ALTERATIONS BUT RATHER WITH THE DEREGULATION OF MMP-9-TARGETING MIRS. THEN, WE FIRST DEMONSTRATED THAT MIR?149 DOWNREGULATION WAS DIRECTLY INVOLVED IN THE MMP-9 OVEREXPRESSION FOLLOWING A CHRONIC GLUCOCORTICOID EXPOSURE AND THAT MS-275 COULD AMPLIFY THIS OVEREXPRESSION BY INHIBITION OF MIR?149 EXPRESSION AND MIR?520C OVEREXPRESSION. TAKEN TOGETHER, THESE RESULTS INDICATE THAT THE USE OF HDACI IN A CONTEXT OF ACQUIRED GLUCOCORTICOID RESISTANCE COULD MODIFY THE EPIGENETIC LANDSCAPE, HIGHLIGHTING THE IMPORTANCE OF TAKING THE GLUCOCORTICOID RESPONSE STATUS INTO CONSIDERATION IN TREATMENT WITH HDACI. 2017 17 2228 29 EPIGENETIC MODIFICATIONS OF HISTONES IN PERIODONTAL DISEASE. PERIODONTITIS IS A CHRONIC INFECTIOUS DISEASE DRIVEN BY DYSBIOSIS, AN IMBALANCE BETWEEN COMMENSAL BACTERIA AND THE HOST ORGANISM. PERIODONTITIS IS A LEADING CAUSE OF TOOTH LOSS IN ADULTS AND OCCURS IN ABOUT 50% OF THE US POPULATION. IN ADDITION TO THE CLINICAL CHALLENGES ASSOCIATED WITH TREATING PERIODONTITIS, THE PROGRESSION AND CHRONIC NATURE OF THIS DISEASE SERIOUSLY AFFECT HUMAN HEALTH. EMERGING EVIDENCE SUGGESTS THAT PERIODONTITIS IS ASSOCIATED WITH MECHANISMS BEYOND BACTERIA-INDUCED PROTEIN AND TISSUE DEGRADATION. HERE, WE HYPOTHESIZE THAT BACTERIA ARE ABLE TO INDUCE EPIGENETIC MODIFICATIONS IN ORAL EPITHELIAL CELLS MEDIATED BY HISTONE MODIFICATIONS. IN THIS STUDY, WE FOUND THAT DYSBIOSIS IN VIVO LED TO EPIGENETIC MODIFICATIONS, INCLUDING ACETYLATION OF HISTONES AND DOWNREGULATION OF DNA METHYLTRANSFERASE 1. IN ADDITION, IN VITRO EXPOSURE OF ORAL EPITHELIAL CELLS TO LIPOPOLYSACCHARIDES RESULTED IN HISTONE MODIFICATIONS, ACTIVATION OF TRANSCRIPTIONAL COACTIVATORS, SUCH AS P300/CBP, AND ACCUMULATION OF NUCLEAR FACTOR-KAPPAB (NF-KAPPAB). GIVEN THAT ORAL EPITHELIAL CELLS ARE THE FIRST LINE OF DEFENSE FOR THE PERIODONTIUM AGAINST BACTERIA, WE ALSO EVALUATED WHETHER ACTIVATION OF PATHOGEN RECOGNITION RECEPTORS INDUCED HISTONE MODIFICATIONS. WE FOUND THAT ACTIVATION OF THE TOLL-LIKE RECEPTORS 1, 2, AND 4 AND THE NUCLEOTIDE-BINDING OLIGOMERIZATION DOMAIN PROTEIN 1 INDUCED HISTONE ACETYLATION IN ORAL EPITHELIAL CELLS. OUR FINDINGS CORROBORATE THE EMERGING CONCEPT THAT EPIGENETIC MODIFICATIONS PLAY A ROLE IN THE DEVELOPMENT OF PERIODONTITIS. 2016 18 5279 25 PROMOTER-SPECIFIC RELEVANCE OF HISTONE MODIFICATIONS INDUCED BY DEXAMETHASONE DURING THE REGULATION OF PRO-INFLAMMATORY MEDIATORS. GLUCOCORTICOSTEROIDS (GCS) ARE WIDELY USED TO TREAT DIFFERENT KINDS OF CHRONIC INFLAMMATORY AND IMMUNE DISEASES THROUGH TRANSCRIPTIONAL REGULATION OF INFLAMMATORY GENES. MODULATION OF GENE EXPRESSION BY GCS IS KNOWN TO OCCUR THROUGH DIVERSE MECHANISMS OF VARYING RELEVANCE TO SPECIFIC CLASSES OF GENES. EPIGENETIC MODIFICATIONS ARE INDEED A PIVOTAL REGULATORY FEATURE OF GLUCOCORTICOID RECEPTOR AND OTHER TRANSCRIPTION FACTORS. IN THIS STUDY, HISTONE POST-TRANSLATIONAL MODIFICATIONS WERE INVESTIGATED FOR THEIR INVOLVEMENT IN THE REGULATION OF SELECTED PRO-INFLAMMATORY GENES - EXPRESSED IN HUMAN MONOCYTE-DERIVED MACROPHAGES - IN RESPONSE TO TREATMENT WITH SYNTHETIC GC DEXAMETHASONE (DEX). WE SHOW THAT HISTONE TAIL ACETYLATION STATUS IS MODIFIED FOLLOWING DEX ADMINISTRATION, THROUGH DISTINCT AND ALTERNATIVE MECHANISMS AT THE PROMOTERS OF INTERLEUKIN-8 AND INTERLEUKIN-23. IN ADDITION TO HISTONE H3 ACETYLATION, OUR RESULTS DEMONSTRATE THAT H3 LYSINE 4 TRIMETHYLATION IS AFFECTED FOLLOWING DRUG TREATMENT. 2014 19 5711 38 SIRT1 IS A HIGHLY NETWORKED PROTEIN THAT MEDIATES THE ADAPTATION TO CHRONIC PHYSIOLOGICAL STRESS. SIRT1 IS A NAD(+)-DEPENDENT PROTEIN DEACETYLASE THAT HAS A VERY LARGE NUMBER OF ESTABLISHED PROTEIN SUBSTRATES AND AN EQUALLY IMPRESSIVE LIST OF BIOLOGICAL FUNCTIONS THOUGHT TO BE REGULATED BY ITS ACTIVITY. PERHAPS AS NOTABLE IS THE REMARKABLE NUMBER OF POINTS OF CONFLICT CONCERNING THE ROLE OF SIRT1 IN BIOLOGICAL PROCESSES. FOR EXAMPLE, EVIDENCE EXISTS SUGGESTING THAT SIRT1 IS A TUMOR SUPPRESSOR, IS AN ONCOGENE, OR HAS NO EFFECT ON ONCOGENESIS. SIMILARLY, SIRT1 IS VARIABLY REPORTED TO INDUCE, INHIBIT, OR HAVE NO EFFECT ON AUTOPHAGY. WE BELIEVE THAT THE RESOLUTION OF MANY CONFLICTING RESULTS IS POSSIBLE BY CONSIDERING RECENT REPORTS INDICATING THAT SIRT1 IS AN IMPORTANT HUB INTERACTING WITH A COMPLEX NETWORK OF PROTEINS THAT COLLECTIVELY REGULATE A WIDE VARIETY OF BIOLOGICAL PROCESSES INCLUDING CANCER AND AUTOPHAGY. A NUMBER OF THE INTERACTING PROTEINS ARE THEMSELVES HUBS THAT, LIKE SIRT1, UTILIZE INTRINSICALLY DISORDERED REGIONS FOR THEIR PROMISCUOUS INTERACTIONS. MANY STUDIES INVESTIGATING SIRT1 FUNCTION HAVE BEEN CARRIED OUT ON CELL LINES CARRYING UNDETERMINED NUMBERS OF ALTERATIONS TO THE PROTEINS COMPRISING THE SIRT1 NETWORK OR ON INBRED MOUSE STRAINS CARRYING FIXED MUTATIONS AFFECTING SOME OF THESE PROTEINS. THUS, THE EFFECTS OF MODULATING SIRT1 AMOUNT AND/OR ACTIVITY ARE IMPORTANTLY DETERMINED BY THE GENETIC BACKGROUND OF THE CELL (OR THE INBRED STRAIN OF MICE), AND THE EFFECTS ATTRIBUTED TO SIRT1 ARE SYNTHETIC WITH THE BACKGROUND OF MUTATIONS AND EPIGENETIC DIFFERENCES BETWEEN CELLS AND ORGANISMS. WORK ON MICE CARRYING ALTERATIONS TO THE SIRT1 GENE SUGGESTS THAT THE NETWORK IN WHICH SIRT1 FUNCTIONS PLAYS AN IMPORTANT ROLE IN MEDIATING PHYSIOLOGICAL ADAPTATION TO VARIOUS SOURCES OF CHRONIC STRESS SUCH AS CALORIE RESTRICTION AND CALORIE OVERLOAD. WHETHER THE CATALYTIC ACTIVITY OF SIRT1 AND THE NUCLEAR CONCENTRATION OF THE CO-FACTOR, NAD(+), ARE RESPONSIBLE FOR MODULATING THIS ACTIVITY REMAINS TO BE DETERMINED. HOWEVER, THE EFFECT OF MODULATING SIRT1 ACTIVITY MUST BE INTERPRETED IN THE CONTEXT OF THE CELL OR TISSUE UNDER INVESTIGATION. INDEED, FOR SIRT1, WE ARGUE THAT CONTEXT IS EVERYTHING. 2013 20 4497 30 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