1 122 116 A SYSTEMATIC REVIEW ON FLUORIDE-INDUCED EPIGENETIC TOXICITY IN MAMMALS. FLUORIDE, ONE OF THE GLOBAL GROUNDWATER CONTAMINANTS, IS UBIQUITOUS IN OUR DAY-TO-DAY LIFE FROM VARIOUS NATURAL AND ANTHROPOGENIC SOURCES. NUMEROUS IN VITRO, IN VIVO, AND EPIDEMIOLOGICAL STUDIES ARE CONDUCTED TO UNDERSTAND THE EFFECT OF FLUORIDE ON BIOLOGICAL SYSTEMS. A LOW CONCENTRATION OF FLUORIDE IS REPORTED TO INCREASE ORAL HEALTH, WHEREAS CHRONIC EXPOSURE TO HIGHER CONCENTRATIONS CAUSES FLUORIDE TOXICITY (FLUOROSIS). IT INCLUDES DENTAL FLUOROSIS, SKELETAL FLUOROSIS, AND FLUORIDE TOXICITY IN SOFT TISSUES. THE MECHANISM OF FLUORIDE TOXICITY HAS BEEN REVIEWED EXTENSIVELY. HOWEVER, EPIGENETIC REGULATION IN FLUORIDE TOXICITY HAS NOT BEEN REVIEWED. THIS SYSTEMATIC REVIEW SUMMARIZES THE CURRENT KNOWLEDGE REGARDING FLUORIDE-INDUCED EPIGENETIC TOXICITY IN THE IN VITRO, IN VIVO, AND EPIDEMIOLOGICAL STUDIES IN MAMMALIAN SYSTEMS. WE EXAMINED FOUR DATABASES FOR THE ASSOCIATION BETWEEN EPIGENETICS AND FLUORIDE EXPOSURE. OUT OF 932 ARTICLES (AS OF 31 MARCH 2022), 39 MET OUR INCLUSION CRITERIA. MOST OF THE STUDIES FOCUSED ON DIFFERENT GENES, AND OVERALL, PRELIMINARY EVIDENCE FOR EPIGENETIC REGULATION OF FLUORIDE TOXICITY WAS IDENTIFIED. WE FURTHER HIGHLIGHT THE NEED FOR EPIGENOME STUDIES RATHER THAN CANDIDATE GENES AND PROVIDE RECOMMENDATIONS FOR FUTURE RESEARCH. OUR RESULTS INDICATE A CORRELATION BETWEEN FLUORIDE EXPOSURE AND EPIGENETIC PROCESSES. FURTHER STUDIES ARE WARRANTED TO ELUCIDATE AND CONFIRM THE MECHANISM OF EPIGENETIC ALTERATIONS MEDIATED FLUORIDE TOXICITY. 2022 2 5555 27 ROLE OF FLUORIDE INDUCED EPIGENETIC ALTERATIONS IN THE DEVELOPMENT OF SKELETAL FLUOROSIS. FLUORIDE IS AN ESSENTIAL TRACE ELEMENT REQUIRED FOR PROPER BONE AND TOOTH DEVELOPMENT. SYSTEMIC HIGH EXPOSURE TO FLUORIDE THROUGH ENVIRONMENTAL EXPOSURE (DRINKING WATER AND FOOD) MAY RESULT IN TOXICITY CAUSING A DISORDER CALLED FLUOROSIS. IN THE PRESENT STUDY, WE INVESTIGATED THE ALTERATION IN DNA METHYLATION PROFILE WITH CHRONIC EXPOSURE (30 DAYS) TO FLUORIDE (8 MG/L) AND ITS RELEVANCE IN THE DEVELOPMENT OF FLUOROSIS. WHOLE GENOME BISULFITE SEQUENCING (WGBS) WAS CARRIED OUT IN HUMAN OSTEOSARCOMA CELLS (HOS) EXPOSED TO FLUORIDE. WHOLE GENOME BISULFITE SEQUENCING (WGBS) AND FUNCTIONAL ANNOTATION OF DIFFERENTIALLY METHYLATED GENES INDICATE ALTERATIONS IN METHYLATION STATUS OF GENES INVOLVED IN BIOLOGICAL PROCESSES ASSOCIATED WITH BONE DEVELOPMENT PATHWAYS. COMBINED ANALYSIS OF PROMOTER DNA HYPER METHYLATION, STRING: FUNCTIONAL PROTEIN ASSOCIATION NETWORKS AND GENE EXPRESSION ANALYSIS REVEALED EPIGENETIC ALTERATIONS IN BMP1, METAP2, MMP11 AND BACH1 GENES, WHICH PLAYS A ROLE IN THE EXTRACELLULAR MATRIX DISASSEMBLY, COLLAGEN CATABOLIC/ORGANIZATION PROCESS, SKELETAL MORPHOGENESIS/DEVELOPMENT, OSSIFICATION AND OSTEOBLAST DEVELOPMENT. THE PRESENT STUDY SHOWS THAT FLUORIDE CAUSES PROMOTER DNA HYPERMETHYLATION IN BMP1, METAP2, MMP11 AND BACH1 GENES WITH SUBSEQUENT DOWN-REGULATION IN THEIR EXPRESSION LEVEL (RNA LEVEL). THE RESULTS IMPLIES THAT FLUORIDE INDUCED DNA HYPERMETHYLATION OF THESE GENES MAY HAMPER EXTRACELLULAR MATRIX DEPOSITION, CARTILAGE FORMATION, ANGIOGENESIS, VASCULAR SYSTEM DEVELOPMENT AND POROSITY OF BONE, THUS PROMOTE SKELETAL FLUOROSIS. 2019 3 908 33 CHRONIC EXPOSURE TO ENVIRONMENTALLY RELEVANT CONCENTRATION OF FLUORIDE IMPAIRS OSTEOBLAST'S COLLAGEN SYNTHESIS AND MATRIX MINERALIZATION: INVOLVEMENT OF EPIGENETIC REGULATION IN SKELETAL FLUOROSIS. GLOBALLY, 200 MILLION PEOPLE ARE SUFFERING FROM TOXIC MANIFESTATIONS OF FLUORIDE(F), DENTAL AND SKELETAL FLUOROSIS; UNFORTUNATELY, THERE IS NO TREATMENT. TO UNRAVEL THE PATHOGENESIS OF SKELETAL FLUOROSIS, WE ESTABLISHED FLUOROSIS MICE BY TREATING ENVIRONMENTALLY RELEVANT CONCENTRATION OF F (15 PPM NAF) THROUGH DRINKING WATER FOR 4 MONTHS. AS IN SKELETAL FLUOROSIS, LOCOMOTOR DISABILITY, CRIPPLING DEFORMITIES OCCUR AND THUS, OUR HYPOTHESIS WAS F MIGHT ADVERSELY AFFECTS COLLAGEN WHICH GIVES THE BONE TENSILE STRENGTH. THIS WORK INEVITABLY HAD TO BE CARRIED OUT ON OSTEOBLAST CELLS, RESPONSIBLE FOR SYNTHESIS, DEPOSITION, AND MINERALIZATION OF BONE MATRIX. ISOLATED OSTEOBLAST CELLS WERE CONFIRMED BY ALP ACTIVITY AND MINERALIZED NODULES FORMATION. EXPRESSION OF COLLAGEN COL1A1, COL1A2, COL1A1 WAS SIGNIFICANTLY REDUCED IN TREATED MICE. FURTHER, A STUDY REVEALED THE INVOLVEMENT OF EPIGENETIC REGULATION BY PROMOTER HYPERMETHYLATION OF COL1A1; EXPRESSIONAL ALTERATIONS OF TRANSCRIPTION FACTORS, CALCIUM CHANNELS AND OTHER GENES E.G., CBFA-1, TGF-BETA1, BMP1, SP1, SP7, NF-(K)B P65, BMP-2, BGLAP, GPRC6A AND CAV(1.2) ARE ASSOCIATED WITH IMPAIRMENT OF COLLAGEN SYNTHESIS, DEPOSITION AND DECREASED MINERALIZATION THUS, ENFEEBLING BONE HEALTH. THIS STUDY INDICATES THE POSSIBLE ASSOCIATION OF EPIGENETIC REGULATION IN SKELETAL FLUOROSIS. HOWEVER, NO ASSOCIATION WAS FOUND BETWEEN POLYMORPHISMS IN THE COL1A1 (RSAI, HINDIII) AND COL1A2 (RSAI, HINDIII) GENES WITH FLUOROSIS IN MICE. 2023 4 5556 28 ROLE OF FLUORIDE INDUCED HISTONE TRIMETHYLATION IN DEVELOPMENT OF SKELETAL FLUOROSIS. CHRONIC EXPOSURE TO FLUORIDE HAS BEEN ASSOCIATED WITH THE DEVELOPMENT OF SKELETAL FLUOROSIS. LIMITED REPORTS ARE AVAILABLE ON FLUORIDE INDUCED HISTONE MODIFICATION. HOWEVER, THE ROLE OF HISTONE MODIFICATION IN THE PATHOGENESIS OF SKELETAL FLUOROSIS IS NOT INVESTIGATED. IN THE PRESENT STUDY, WE HAVE INVESTIGATED THE ROLE OF FLUORIDE INDUCED HISTONE MODIFICATION ON FLUOROSIS DEVELOPMENT USING HUMAN OSTEOSARCOMA (HOS) CELL LINE. THE EXPRESSION OF HISTONE METHYLTRANSFERASES (EHMT1 AND EHZ2) AND LEVEL OF GLOBAL HISTONE TRIMETHYLATION (H3K9 AND H3K27) HAVE BEEN ASSESSED AND OBSERVED TO BE INCREASED SIGNIFICANTLY AFTER FLUORIDE EXPOSURE (8 MG/L). EPITECT CHROMATIN IMMUNOPRECIPITATION (CHIP) QPCR ARRAY (HUMAN TGFBETA/BMP SIGNALING PATHWAY) WAS PERFORMED TO ASSESS THE H3K9 TRIMETHYLATION AT PROMOTER REGIONS OF PATHWAY-SPECIFIC GENES. H3K9 CHIP PCR ARRAY ANALYSIS IDENTIFIED HYPER H3K9 TRIMETHYLATION IN PROMOTER REGIONS OF TGFBR2 AND SMAD3. QPCR AND STRING ANALYSIS WAS CARRIED OUT TO DETERMINE THE REPRESSIVE EPIGENETIC EFFECT OF H3K9 TRIMETHYLATION ON EXPRESSION PATTERN AND FUNCTIONAL ASSOCIATION OF IDENTIFIED GENES. IDENTIFIED GENES (TGFBR2 AND SMAD3) SHOWED DOWN-REGULATION WHICH CONFIRMS THE REPRESSIVE EPIGENETIC EFFECT OF PROMOTER H3K9 HYPER TRIMETHYLATION. EXPRESSION OF TWO OTHER VITAL GENES COL1A1 AND MMP13 INVOLVED IN TGFBR2-SMAD SIGNALING PATHWAY WAS ALSO FOUND TO BE DOWN-REGULATED WITH A DECREASE IN EXPRESSION OF TGFBR2 AND SMAD3. STRING ANALYSIS REVEALED FUNCTIONAL ASSOCIATION AND INVOLVEMENT OF IDENTIFIED GENES TGFBR2, SMAD3, COL1A1 AND MMP13 IN THE COLLAGEN AND CARTILAGE DEVELOPMENT/MORPHOGENESIS, CONNECTIVE TISSUE FORMATION, BIO-MINERAL TISSUE DEVELOPMENT, ENDOCHONDRAL BONE FORMATION, BONE AND SKELETAL MORPHOGENESIS. IN CONCLUSION, PRESENT INVESTIGATION IS A FIRST ATTEMPT TO LINK FLUORIDE INDUCED HYPER H3K9 TRI-METHYLATION MEDIATED REPRESSION OF TGFBR2 AND SMAD3 WITH THE DEVELOPMENT OF SKELETAL FLUOROSIS. 2018 5 907 23 CHRONIC EXPOSURE TO ENVIRONMENTALLY RELEVANT CONCENTRATION OF FLUORIDE ALTERS OGG1 AND RAD51 EXPRESSIONS IN MICE: INVOLVEMENT OF EPIGENETIC REGULATION. CHRONIC EXPOSURE TO FLUORIDE (F) BEYOND THE PERMISSIBLE LIMIT (1.5 PPM) IS KNOWN TO CAUSE DETRIMENTAL HEALTH EFFECTS BY INDUCTION OF OXIDATIVE STRESS-MEDIATED DNA DAMAGE OVERPOWERING THE DNA REPAIR MACHINERY. IN THE PRESENT STUDY, WE ASSESSED F INDUCED OXIDATIVE STRESS THROUGH MONITORING BIOCHEMICAL PARAMETERS AND LOOKED INTO THE EFFECT OF CHRONIC F EXPOSURE ON TWO CRUCIAL DNA REPAIR GENES OGG1 AND RAD51 HAVING IMPORTANT ROLE AGAINST ROS INDUCED DNA DAMAGES. TO ADDRESS THIS ISSUE, WE EXPOSED SWISS ALBINO MICE TO AN ENVIRONMENTALLY RELEVANT CONCENTRATION OF FLUORIDE (15 PPM NAF) FOR 8 MONTHS. RESULTS REVEALED HISTOARCHITECTURAL DAMAGES IN LIVER, BRAIN, KIDNEY AND SPLEEN. DEPLETION OF GSH, INCREASE IN LIPID PEROXIDATION AND CATALASE ACTIVITY IN LIVER AND BRAIN CONFIRMED THE GENERATION OF OXIDATIVE STRESS. QRT-PCR RESULT SHOWED THAT EXPRESSIONS OF OGG1 AND RAD51 WERE ALTERED AFTER F EXPOSURE IN THE AFFECTED ORGANS. PROMOTER HYPERMETHYLATION WAS ASSOCIATED WITH THE DOWNREGULATION OF RAD51. F-INDUCED DNA DAMAGE AND THE COMPROMISED DNA REPAIR MACHINERY TRIGGERED INTRINSIC PATHWAY OF APOPTOSIS IN LIVER AND BRAIN. THE PRESENT STUDY INDICATES THE POSSIBLE ASSOCIATION OF EPIGENETIC REGULATION WITH F INDUCED NEUROTOXICITY. 2020 6 143 22 ABERRANT DNA METHYLATION OF TWO TUMOR SUPPRESSOR GENES, P14(ARF) AND P15(INK4B), AFTER CHRONIC OCCUPATIONAL EXPOSURE TO LOW LEVEL OF BENZENE. BACKGROUND: EXPOSURE TO BENZENE WOULD BE ASSOCIATED WITH MANY DISEASES INCLUDING LEUKEMIA. EPIGENETIC ALTERATIONS SEEM TO BE AMONG THE MAIN MECHANISMS INVOLVED. OBJECTIVE: TO DETERMINE IF CHRONIC OCCUPATIONAL EXPOSURE TO LOW LEVEL OF BENZENE WOULD BE ASSOCIATED WITH DNA METHYLATION. METHODS: GLOBAL DNA METHYLATION AND PROMOTER-SPECIFIC METHYLATION OF THE TWO TUMOR SUPPRESSOR GENES, P14(ARF) AND P15(INK4B), WERE ASSESSED EMPLOYING METHYLATION-SPECIFIC PCR USING THE DNA EXTRACTED FROM 40 PETROCHEMICAL WORKERS EXPOSED TO AMBIENT BENZENE LEVELS OF <1 PPM, AND 31 OFFICE WORKERS NOT EXPOSED TO BENZENE OR ITS DERIVATIVES. RESULTS: WHILE AN INCREASE IN GLOBAL DNA METHYLATION OF 5% IN P14(ARF) (P=0.501) AND 28% IN P15(INK4B) (P=0.02) GENES WAS OBSERVED IN THE EXPOSED GROUP, NO HYPERMETHYLATION IN EITHER OF THE STUDIED GENES WAS OBSERVED IN THE UNEXPOSED GROUP. NO SIGNIFICANT ASSOCIATION WAS FOUND BETWEEN THE FREQUENCY OF ABERRANT METHYLATION AND EITHER OF AGE, WORK EXPERIENCE, AND SMOKING HABIT IN THE EXPOSED GROUP. CONCLUSION: CHRONIC OCCUPATIONAL EXPOSURE TO LOWER THAN THE PERMISSIBLE EXPOSURE LIMIT OF BENZENE MAY STILL RESULT IN DNA METHYLATION OF TUMOR SUPPRESSOR GENES THAT MAY ULTIMATELY LEAD TO DEVELOPMENT OF CANCER. 2018 7 3609 31 IN UTERO ARSENIC EXPOSURE AND EPIGENOME-WIDE ASSOCIATIONS IN PLACENTA, UMBILICAL ARTERY, AND HUMAN UMBILICAL VEIN ENDOTHELIAL CELLS. EXPOSURE TO ARSENIC EARLY IN LIFE HAS BEEN ASSOCIATED WITH INCREASED RISK OF SEVERAL CHRONIC DISEASES AND IS BELIEVED TO ALTER EPIGENETIC PROGRAMMING IN UTERO. IN THE PRESENT STUDY, WE EVALUATE THE EPIGENOME-WIDE ASSOCIATION OF ARSENIC EXPOSURE IN UTERO AND DNA METHYLATION IN PLACENTA (N = 37), UMBILICAL ARTERY (N = 45) AND HUMAN UMBILICAL VEIN ENDOTHELIAL CELLS (HUVEC) (N = 52) IN A BIRTH COHORT USING THE INFINIUM HUMANMETHYLATION450 BEADCHIP ARRAY. UNADJUSTED AND CELL MIXTURE ADJUSTED ASSOCIATIONS FOR EACH TISSUE WERE EXAMINED ALONG WITH ENRICHMENT ANALYSES RELATIVE TO CPG ISLAND LOCATION AND OMNIBUS PERMUTATION TESTS OF ASSOCIATION AMONG BIOLOGICAL PATHWAYS. ONE CPG IN ARTERY (CG26587014) AND 4 CPGS IN PLACENTA (CG12825509; CG20554753; CG23439277; CG21055948) REACHED A BONFERRONI ADJUSTED LEVEL OF SIGNIFICANCE. SEVERAL CPGS WERE DIFFERENTIALLY METHYLATED IN ARTERY AND PLACENTA WHEN CONTROLLING THE FALSE DISCOVERY RATE (Q-VALUE<0.05), BUT NONE IN HUVEC. ENRICHMENT OF HYPOMETHYLATED CPG ISLANDS WAS OBSERVED FOR ARTERY WHILE HYPERMETHYLATION OF OPEN SEA REGIONS WERE PRESENT IN PLACENTA RELATIVE TO PRENATAL ARSENIC EXPOSURE. THE MELANOGENESIS PATHWAY WAS DIFFERENTIALLY METHYLATED IN ARTERY (MAX F P < 0.001), PLACENTA (MAX F P < 0.001), AND HUVEC (MAX F P = 0.02). SIMILARLY, THE INSULIN-SIGNALING PATHWAY WAS DIFFERENTIALLY METHYLATED IN ARTERY (MAX F P = 0.02), PLACENTA (MAX F P = 0.02), AND HUVEC (MAX F P = 0.02). OUR RESULTS SHOW THAT PRENATAL ARSENIC EXPOSURE CAN ALTER DNA METHYLATION IN ARTERY AND PLACENTA BUT NOT IN HUVEC. FURTHER STUDIES ARE NEEDED TO DETERMINE IF THESE ALTERATIONS IN DNA METHYLATION MEDIATE THE EFFECT OF PRENATAL ARSENIC EXPOSURE AND HEALTH OUTCOMES LATER IN LIFE. 2015 8 974 26 CHRONIC OCCUPATIONAL EXPOSURE ENDURED BY TOBACCO FARMERS FROM BRAZIL AND ASSOCIATION WITH DNA DAMAGE. TOBACCO FARMING IS AN IMPORTANT ECONOMIC INCOME IN BRAZIL, ALTHOUGH IT HAS BEEN CHALLENGED AS REGARD THE OCCUPATIONAL EXPOSURE TO BOTH PESTICIDES AND NICOTINE ENDURED BY FARMERS. CHRONIC OCCUPATIONAL EXPOSURE TO COMPLEX MIXTURES CAN LEAD TO HEALTH HAZARDOUS. WE EXAMINED GENOMIC INSTABILITY AND EPIGENETIC CHANGES IN TOBACCO FARMERS OCCUPATIONALLY EXPOSED TO PESTICIDE MIXTURES AND NICOTINE AT TOBACCO FIELDS. DNA DAMAGE WAS ASSESSED BY ALKALINE COMET ASSAY IN BLOOD CELLS. GENOMIC DNA WAS ISOLATED, AND TELOMERE LENGTH WAS MEASURED USING QUANTITATIVE POLYMERASE CHAIN REACTION ASSAY. WE MEASURED 5-METHYL-2'-DEOXYCYTIDINE, A MARKER OF GLOBAL DNA METHYLATION, AND P16 PROMOTER METHYLATION. THE OXIDATIVE PROFILE WAS EVALUATED BY TROLOX EQUIVALENT ANTIOXIDANT CAPACITY AND LIPID PEROXIDATION (THIOBARBITURIC ACID REACTIVE SUBSTANCES) IN SERUM. EXPOSURE PARAMETERS, PLASMA COTININE AND INORGANIC ELEMENT LEVELS, WERE ALSO MEASURED. DNA DAMAGE WAS SIGNIFICANTLY ELEVATED FOR FARMERS IN RELATION TO UNEXPOSED GROUP (P < 0.001; MANN-WHITNEY TEST) AND POSITIVELY ASSOCIATED WITH YEARS OF EXPOSURE. INVERSE RELATIONSHIP BETWEEN DNA DAMAGE AND TOTAL EQUIVALENT ANTIOXIDANT ACTIVITY WAS DEMONSTRATED FOR EXPOSED AND UNEXPOSED GROUPS. EXPOSED GROUP SHOWED SIGNIFICANTLY SHORTER TELOMERES (P < 0.001; UNPAIRED T-TEST) AND DNA HYPOMETHYLATION (P < 0.001; UNPAIRED T-TEST), AS WELL AS P16 HYPERMETHYLATION (P = 0.003; MANN-WHITNEY TEST). LIPID PEROXIDATION WAS INCREASED FOR EXPOSED GROUP IN RELATION TO UNEXPOSED ONE (P = 0.02; MANN-WHITNEY TEST) AND PRESENTED A POSITIVE CORRELATION WITH GLOBAL DNA METHYLATION (P = 0.0264). FARMERS HAVE INCREASED PLASMA COTININE LEVELS (P < 0.001) AND INORGANIC ELEMENTS (PHOSPHORUS, SULPHUR AND CHLORINE) IN RELATION TO UNEXPOSED GROUP. ELEVATED OXIDATIVE STRESS LEVELS DUE TO CHRONIC OCCUPATIONAL PESTICIDE MIXTURES AND NICOTINE EXPOSURE IN TOBACCO FARMERS WERE ASSOCIATED WITH HIGHER DNA DAMAGE, SHORTER TELOMERES AND ALTERED DNA METHYLATION. TELOMERE-ACCELERATED ATTRITION DUE TO EXPOSURE MAY BE POTENTIAL INTERMEDIATE STEP BEFORE A DISEASE STATE. 2018 9 4008 26 LOW DOSE OF URANIUM INDUCES MULTIGENERATIONAL EPIGENETIC EFFECTS IN RAT KIDNEY. PURPOSE: A PROTOCOL OF CHRONIC EXPOSURE TO LOW DOSE OF URANIUM WAS ESTABLISHED IN ORDER TO DISTINGUISH THE SEXUAL DIFFERENCES AND THE DEVELOPMENTAL PROCESS THAT ARE CRITICAL WINDOWS FOR EPIGENETIC EFFECTS OVER GENERATIONS. METHODS: BOTH MALE AND FEMALE RATS WERE CONTAMINATED THROUGH THEIR DRINKING WATER WITH A NON-TOXIC SOLUTION OF URANYL NITRATE FOR 9 MONTHS. THE EXPOSED GENERATION (F0) AND THE FOLLOWING TWO GENERATIONS (F1 AND F2) WERE EXAMINED. CLINICAL MONITORING, GLOBAL DNA METHYLATION PROFILE AND DNA METHYLTRANSFERASES (DNMTS) GENE EXPRESSION WERE ANALYZED IN KIDNEYS. RESULTS: WHILE THE BODY WEIGHT OF F1 MALES INCREASED, A SMALL DECREASE IN KIDNEY AND BODY WEIGHT WAS OBSERVED IN F2 MALES. IN ADDITION, GLOBAL DNA HYPERMETHYLATION PROFILE IN KIDNEY CELLS WAS OBSERVED IN F1 AND F2 MALES. QPCR RESULTS REVEAL A SIGNIFICANT INCREASE OF METHYLTRANSFERASE GENES EXPRESSION (DNMT1 AND DNMT3A) FOR F2 FEMALES. CONCLUSIONS: IN THE FIELD OF PUBLIC HEALTH POLICY AND TO RAISE ATTENTION TO GENERATIONAL EFFECTS FOR THE RISK ASSESSMENT OF THE ENVIRONMENTAL EXPOSURES, LOW DOSES OF URANIUM DO NOT IMPLY CLINICAL EFFECTS ON ADULT EXPOSED RATS. HOWEVER, OUR RESULTS CONFIRM THE IMPORTANCE OF THE DEVELOPMENTAL WINDOWS' SENSITIVITY IN ADDITION TO THE SEXUAL DIMORPHISMS OF THE OFFSPRING. 2018 10 4076 22 MATERNAL HIGH-FAT DIET MODIFIES EPIGENETIC MARKS H3K27ME3 AND H3K27AC IN BONE TO REGULATE OFFSPRING OSTEOBLASTOGENESIS IN MICE. STUDIES FROM BOTH HUMANS AND ANIMAL MODELS INDICATED THAT MATERNAL CHRONIC POOR-QUALITY DIET, ESPECIALLY A HIGH FAT DIET (HFD), IS SIGNIFICANTLY ASSOCIATED WITH REDUCED BONE DENSITY AND CHILDHOOD FRACTURES IN OFFSPRING. WHEN PREVIOUSLY STUDIED IN A RAT MODEL, OUR DATA SUGGESTED THAT MATERNAL HFD CHANGES EPIGENETIC MARKS SUCH AS DNA METHYLATION AND HISTONE MODIFICATIONS TO CONTROL OSTEOBLAST METABOLISM. IN MOUSE EMBRYONIC AND POSTNATAL OFFSPRING BONE SAMPLES, A CHIP-SEQUENCING (CHIP-SEQ)-BASED GENOME-WIDE METHOD WAS USED TO LOCATE THE REPRESSIVE HISTONE MARK H3K27ME3 (MEDIATED VIA THE POLYCOMB HISTONE METHYLTRANSFERASE, EZH2) AND EXPRESSIVE HISTONE MARK H3K27AC (P300/CBP MEDIATED) THROUGHOUT THE GENOME. USING ISOLATED MOUSE EMBRYONIC CELLS FROM FOETAL CALVARIA (OSTEOBLAST-LIKE CELLS), H3K27ME3 CHIP-SEQ SHOWED THAT 147 GENE BODIES AND 26 GENE PROMOTERS IN HFD EMBRYOTIC SAMPLES HAD A GREATER THAN TWOFOLD INCREASE IN H3K27ME PEAKS COMPARED TO CONTROLS. AMONG THE HFD SAMPLES, PTHLH AND COL2A1 THAT ARE IMPORTANT GENES PLAYING ROLES DURING CHONDRO- AND OSTEOGENESIS HAD SIGNIFICANTLY ENRICHED LEVELS OF H3K27ME3. THEIR DECREASED MRNA EXPRESSION WAS CONFIRMED BY REAL-TIME PCR AND STANDARD CHIP ANALYSIS, INDICATING A STRONG ASSOCIATION WITH EZH2 MEDIATED H3K27ME3 EPIGENETIC CHANGES. USING EMBRYONIC CALVARIA OSTEOBLASTIC CELLS AND OFFSPRING BONE SAMPLES, H3K27AC CHIP-SEQ ANALYSIS SHOWED THAT OSTEOBLAST INHIBITOR GENES TNFAIP3 AND TWIST1 HAD SIGNIFICANTLY ENRICHED PEAKS OF H3K27AC IN HFD SAMPLES COMPARED TO CONTROLS. THEIR INCREASED GENE EXPRESSION AND ASSOCIATION WITH H3K27AC WERE ALSO CONFIRMED BY REAL-TIME PCR AND STANDARD CHIP ANALYSIS. THESE FINDINGS INDICATE THAT CHRONIC MATERNAL HFD CHANGES HISTONE TRIMETHYLATION AND ACETYLATION EPIGENETIC MARKS TO REGULATE EXPRESSION OF GENES CONTROLLING OSTEOBLASTOGENESIS. 2022 11 4180 31 MERCURY EXPOSURE INDUCES CYTOSKELETON DISRUPTION AND LOSS OF RENAL FUNCTION THROUGH EPIGENETIC MODULATION OF MMP9 EXPRESSION. MERCURY IS ONE OF THE MAJOR HEAVY METAL POLLUTANTS OCCURRING IN ELEMENTAL, INORGANIC AND ORGANIC FORMS. DUE TO BAN ON MOST INORGANIC MERCURY CONTAINING PRODUCTS, HUMAN EXPOSURE TO MERCURY GENERALLY OCCURS AS METHYLMERCURY (MEHG) BY CONSUMPTION OF CONTAMINATED FISH AND OTHER SEA FOOD. ANIMAL AND EPIDEMIOLOGICAL STUDIES INDICATE THAT MEHG AFFECTS NEURAL AND RENAL FUNCTION. OUR STUDY IS FOCUSED ON NEPHROTOXIC POTENTIAL OF MEHG. IN THIS STUDY, WE HAVE SHOWN FOR THE FIRST TIME HOW MEHG COULD EPIGENETICALLY MODULATE MATRIX METALLOPROTEINASE 9(MMP9) TO PROMOTE NEPHROTOXICITY USING AN ANIMAL MODEL OF SUB CHRONIC MEHG EXPOSURE. MEHG CAUSED RENAL TOXICITY AS WAS SEEN BY INCREASED LEVELS OF SERUM CREATININE AND EXPRESSION OF EARLY NEPHROTOXICITY MARKERS (KIM-1, CLUSTERIN, IP-10, AND TIMP). MEHG EXPOSURE ALSO CORRELATED STRONGLY WITH INDUCTION OF MMP9 MRNA AND PROTEIN IN A DOSE DEPENDENT MANNER. FURTHER, WHILE INDUCTION OF MMP9 PROMOTED CYTOSKELETON DISRUPTION AND LOSS OF CELL-CELL ADHESION (LOSS OF F-ACTIN, VIMENTIN AND FIBRONECTIN), INHIBITION OF MMP9 WAS FOUND TO REDUCE THESE DISRUPTIONS. MECHANISTIC STUDIES BY CHIP ANALYSIS SHOWED THAT MEHG MODULATED MMP9 BY PROMOTING DEMETHYLATION OF ITS REGULATORY REGION TO INCREASE ITS EXPRESSION. BISULFITE SEQUENCING IDENTIFIED CRITICAL CPGS IN THE FIRST EXON OF MMP9 WHICH WERE DEMETHYLATED FOLLOWING MEHG EXPOSURE. CHIP STUDIES ALSO SHOWED LOSS OF METHYL BINDING PROTEIN, MECP2 AND TRANSCRIPTION FACTOR PEA3 AT THE DEMETHYLATED SITE CONFIRMING DECREASED CPG METHYLATION. OUR STUDIES THUS SHOW HOW MEHG COULD EPIGENETICALLY MODULATE MMP9 TO PROMOTE CYTOSKELETON DISRUPTION LEADING TO LOSS OF RENAL FUNCTION. 2017 12 5267 26 PROMOTER ACTIVITY-BASED CASE-CONTROL ASSOCIATION STUDY ON SLC6A4 HIGHLIGHTING HYPERMETHYLATION AND ALTERED AMYGDALA VOLUME IN MALE PATIENTS WITH SCHIZOPHRENIA. ASSOCIATIONS BETWEEN ALTERED DNA METHYLATION OF THE SEROTONIN TRANSPORTER (5-HTT)-ENCODING GENE SLC6A4 AND EARLY LIFE ADVERSITY, MOOD AND ANXIETY DISORDERS, AND AMYGDALA REACTIVITY HAVE BEEN REPORTED. HOWEVER, FEW STUDIES HAVE EXAMINED EPIGENETIC ALTERATIONS OF SLC6A4 IN SCHIZOPHRENIA (SZ). WE EXAMINED CPG SITES OF SLC6A4, WHOSE DNA METHYLATION LEVELS HAVE BEEN REPORTED TO BE ALTERED IN BIPOLAR DISORDER, USING 3 INDEPENDENT COHORTS OF PATIENTS WITH SZ AND AGE-MATCHED CONTROLS. WE FOUND SIGNIFICANT HYPERMETHYLATION OF A CPG SITE IN SLC6A4 IN MALE PATIENTS WITH SZ IN ALL 3 COHORTS. WE SHOWED THAT CHRONIC ADMINISTRATION OF RISPERIDONE DID NOT AFFECT THE DNA METHYLATION STATUS AT THIS CPG SITE USING COMMON MARMOSETS, AND THAT IN VITRO DNA METHYLATION AT THIS CPG SITE DIMINISHED THE PROMOTER ACTIVITY OF SLC6A4. WE THEN GENOTYPED THE 5-HTT-LINKED POLYMORPHIC REGION (5-HTTLPR) AND INVESTIGATED THE RELATIONSHIP AMONG 5-HTTLPR, DNA METHYLATION, AND AMYGDALA VOLUME USING BRAIN IMAGING DATA. WE FOUND THAT PATIENTS HARBORING LOW-ACTIVITY 5-HTTLPR ALLELES SHOWED HYPERMETHYLATION AND THEY SHOWED A NEGATIVE CORRELATION BETWEEN DNA METHYLATION LEVELS AND LEFT AMYGDALA VOLUMES. THESE RESULTS SUGGEST THAT HYPERMETHYLATION OF THE CPG SITE IN SLC6A4 IS INVOLVED IN THE PATHOPHYSIOLOGY OF SZ, ESPECIALLY IN MALE PATIENTS HARBORING LOW-ACTIVITY 5-HTTLPR ALLELES. 2020 13 899 21 CHRONIC EXPOSURE TO A LOW CONCENTRATION OF BISPHENOL A DURING FOLLICLE CULTURE AFFECTS THE EPIGENETIC STATUS OF GERMINAL VESICLES AND METAPHASE II OOCYTES. OBJECTIVE: TO DETERMINE WHETHER EXPOSURE TO LOW CONCENTRATIONS OF THE ENDOCRINE DISRUPTING CHEMICAL BISPHENOL A (BPA) DURING FOLLICLE CULTURE AND OOCYTE GROWTH ALTERS THE METHYLATION STATUS OF DIFFERENTIALLY METHYLATED REGIONS (DMRS) OF IMPRINTED GENES AND HISTONE POSTTRANSLATIONAL MODIFICATION PATTERNS IN MAMMALIAN OOCYTES. DESIGN: COMPARATIVE AND CONTROL STUDY. SETTING: EXPERIMENTAL LABORATORY. ANIMAL(S): C57/BL6JXCBA/CA MICE. INTERVENTION(S): EXPOSURE OF OOCYTES TO 3 NM OR 300 NM BPA DURING FOLLICLE CULTURE FROM PREANTRAL TO ANTRAL STAGE. MAIN OUTCOME MEASURE(S): METHYLATION STATUS OF DMRS OF MATERNALLY IMPRINTED (SNRPN, IGF2R, AND MEST) AND PATERNALLY IMPRINTED GENE(S) (H19) IN MOUSE GERMINAL VESICLE OOCYTES; TRIMETHYLATION OF HISTONE H3K9, ACETYLATION OF HISTONE H4K12, AND DISTANCE BETWEEN CENTROMERES OF SISTER CHROMATIDS IN METAPHASE II OOCYTES. RESULT(S): EXPOSURE TO 3 NM BPA WAS ASSOCIATED WITH SLIGHTLY ACCELERATED FOLLICLE DEVELOPMENT, STATISTICALLY SIGNIFICANT INCREASES IN ALLELE METHYLATION ERRORS IN DMRS OF MATERNALLY IMPRINTED GENES, AND STATISTICALLY SIGNIFICANT DECREASES IN HISTONE H3K9 TRIMETHYLATION AND INTERKINETOCHORE DISTANCE. CONCLUSION(S): THE DISTURBANCES IN OOCYTE GENOMIC IMPRINTING AND MODIFICATION OF POSTTRANSLATIONAL HISTONE AND CENTROMERE ARCHITECTURE PROVIDE THE FIRST LINK BETWEEN LOW BPA EXPOSURES AND INDUCTION OF EPIGENETIC CHANGES THAT MAY CONTRIBUTE TO CHROMOSOME CONGRESSION FAILURES AND MEIOTIC ERRORS, AND TO ALTERED GENE EXPRESSION THAT MIGHT AFFECT HEALTH OF THE OFFSPRING. 2013 14 2031 18 EPIGENETIC CHANGES IN LYMPHOCYTES OF SOLVENT-EXPOSED INDIVIDUALS. AIM: WE INVESTIGATED GLOBAL DNA METHYLATION ALTERATIONS IN LYMPHOCYTES OF SOLVENT WORKERS AND CHRONIC TOXIC ENCEPHALOPATHY (CTE) PATIENTS AND EXPLORED POTENTIAL GENE-ENVIRONMENT INTERACTIONS FOR GST. POPULATION & METHODS: A CROSS-SECTIONAL STUDY WAS SET UP IN 41 REFERENTS, 128 SOLVENT WORKERS AND 23 CTE PATIENTS. RESULTS: WE FOUND A GLOBAL DNA HYPERMETHYLATION IN THE SOLVENT-EXPOSED POPULATION COMPARED WITH THE REFERENTS (P = 0.001, R = -0.544). GLOBAL DNA METHYLATION WAS NEGATIVELY ASSOCIATED WITH EXPOSURE. FURTHERMORE, GSTP1 GENOTYPIC POLYMORPHISM WAS FOUND TO BE SIGNIFICANTLY ASSOCIATED (P = 0.033) WITH GLOBAL DNA HYPOMETHYLATION, WHICH INDICATES A POTENTIAL ROLE FOR GENE-ENVIRONMENT INTERACTION IN THE ETIOLOGY OF SOLVENT-INDUCED NEUROBEHAVIORAL DISORDERS. CONCLUSION: THIS STUDY INDICATES THAT SOLVENT-INDUCED DNA METHYLATION ALTERATIONS HAVE AN IMPACT ON NEUROTOXICITY AND DEVELOPMENT OF CTE. 2012 15 1399 33 DIET-INDUCED OBESITY MODULATES EPIGENETIC RESPONSES TO IONIZING RADIATION IN MICE. BOTH EXPOSURE TO IONIZING RADIATION AND OBESITY HAVE BEEN ASSOCIATED WITH VARIOUS PATHOLOGIES INCLUDING CANCER. THERE IS A CRUCIAL NEED IN BETTER UNDERSTANDING THE INTERACTIONS BETWEEN IONIZING RADIATION EFFECTS (ESPECIALLY AT LOW DOSES) AND OTHER RISK FACTORS, SUCH AS OBESITY. IN ORDER TO EVALUATE RADIATION RESPONSES IN OBESE ANIMALS, C3H AND C57BL/6J MICE FED A CONTROL NORMAL FAT OR A HIGH FAT (HF) DIET WERE EXPOSED TO FRACTIONATED DOSES OF X-RAYS (0.75 GY X4). BONE MARROW MICRONUCLEUS ASSAYS DID NOT SUGGEST A MODULATION OF RADIATION-INDUCED GENOTOXICITY BY HF DIET. USING MSP, WE OBSERVED THAT THE PROMOTERS OF P16 AND DAPK GENES WERE METHYLATED IN THE LIVERS OF C57BL/6J MICE FED A HF DIET (IRRADIATED AND NON-IRRADIATED); MGMT PROMOTER WAS METHYLATED IN IRRADIATED AND/OR HF DIET-FED MICE. IN ADDITION, METHYLATION PCR ARRAYS IDENTIFIED EP300 AND SOCS1 (WHOSE PROMOTERS EXHIBITED HIGHER METHYLATION LEVELS IN NON-IRRADIATED HF DIET-FED MICE) AS POTENTIAL TARGETS FOR FURTHER STUDIES. WE THEN COMPARED MICRORNA REGULATIONS AFTER RADIATION EXPOSURE IN THE LIVERS OF C57BL/6J MICE FED A NORMAL OR AN HF DIET, USING MICRORNA ARRAYS. INTERESTINGLY, RADIATION-TRIGGERED MICRORNA REGULATIONS OBSERVED IN NORMAL MICE WERE NOT OBSERVED IN OBESE MICE. MIR-466E WAS UPREGULATED IN NON-IRRADIATED OBESE MICE. IN VITRO FREE FATTY ACID (PALMITIC ACID, OLEIC ACID) ADMINISTRATION SENSITIZED AML12 MOUSE LIVER CELLS TO IONIZING RADIATION, BUT THE INHIBITION OF MIR-466E COUNTERACTED THIS RADIO-SENSITIZATION, SUGGESTING THAT THE MODULATION OF RADIATION RESPONSES BY DIET-INDUCED OBESITY MIGHT INVOLVE MIR-466E EXPRESSION. ALL TOGETHER, OUR RESULTS SUGGESTED THE EXISTENCE OF DIETARY EFFECTS ON RADIATION RESPONSES (ESPECIALLY EPIGENETIC REGULATIONS) IN MICE, POSSIBLY IN RELATIONSHIP WITH OBESITY-INDUCED CHRONIC OXIDATIVE STRESS. 2014 16 1381 32 DI-(2-ETHYLHEXYL) PHTHALATE TRIGGERS DNA METHYLTRANSFERASE 1 EXPRESSION RESULTING IN ELEVATED CPG-METHYLATION AND ENRICHMENT OF MECP2 IN THE P21 PROMOTER IN VITRO. LEACHING OF THE PLASTIC CONSTITUENTS LEADING TO THEIR CHRONIC EXPOSURE TO HUMANS IS A MAJOR CONCERN FOR OUR ENVIRONMENTAL AND OCCUPATIONAL HEALTH. OUR PREVIOUS AND OTHER NUMEROUS STUDIES HAVE DEMONSTRATED THAT ENVIRONMENTAL CHEMICALS LIKE DI (2-ETHYLHEXYL)-PHTHALATE (DEHP) COULD POSE A RISK TOWARDS THE EPIGENETIC MECHANISMS. YET, THE MECHANISMS UNDERLYING ITS POSSIBLE EPIGENOTOXICITY ARE POORLY UNDERSTOOD. WE AIMED TO ASSESS THE IMPACT OF DEHP EXPOSURE TO THE HUMAN BREAST CANCER CELLS (MCF-7) AND RESULTANT CHANGES IN DNA METHYLATION REGULATORS ULTIMATELY ALTERING THE EXPRESSION OF THE CELL CYCLE REGULATOR P21 AS A MODEL GENE. THE MCF-7 CELLS WERE EXPOSED TO ENVIRONMENTALLY RELEVANT CONCENTRATIONS (50-500 NM) FOR 24 H. THE RESULTS SHOWED THAT DEHP WAS PROLIFERATIVE TOWARDS THE MCF-7 CELLS WHILE IT INDUCED GLOBAL DNA HYPERMETHYLATION WITH SELECTIVE UPREGULATION OF DNMT1 AND MECP2. IN ADDITION, DEHP SIGNIFICANTLY REDUCED P53 PROTEIN AND ITS ENRICHMENT TO THE DNMT1 PROMOTER BINDING SITE, WHILE ELEVATING SP1 AND E2F1 TRANSCRIPTION FACTOR LEVELS, STIMULATING THEIR BINDING TO THE PROMOTER DNA. COINCIDENTLY, INCREASED DNMT1 LEVEL WAS HIGHLY ASSOCIATED WITH LOSS OF P21 EXPRESSION AND INCREASED CYCLIN D1 LEVELS. IMPORTANTLY, THE P21, BUT NOT CYCLIN D1 PROMOTER CPG-DINUCLEOTIDES WERE HYPERMETHYLATED AFTER EXPOSURE TO 500 NM DEHP FOR 24 H. FURTHERMORE, IT WAS OBSERVED THAT DEHP SIGNIFICANTLY ENRICHED DNMT1 AND MECP2 TO THE P21 PROMOTER TO INDUCE DNA METHYLATION-BASED EPIGENETIC SILENCING OF P21, RESULTING IN INCREASED CELL PROLIFERATION. OUR RESULTS SUGGEST DEHP COULD POTENTIALLY INDUCE THE EPIGENETIC ALTERATIONS THAT MIGHT INCREASE THE RISK OF BREAST CANCER, GIVEN THAT THE UNDERLYING MECHANISMS SHOULD BE FULLY ELUCIDATED. 2022 17 3999 24 LOSS OF HDAC3 RESULTS IN NONRECEPTIVE ENDOMETRIUM AND FEMALE INFERTILITY. ENDOMETRIOSIS IS A DISEASE IN WHICH TISSUE THAT NORMALLY GROWS INSIDE THE UTERUS GROWS OUTSIDE THE UTERUS AND CAUSES CHRONIC PELVIC PAIN AND INFERTILITY. HOWEVER, THE EXACT MECHANISMS OF THE PATHOGENESIS OF ENDOMETRIOSIS-ASSOCIATED INFERTILITY ARE UNKNOWN. EPIGENETIC DYSREGULATION HAS RECENTLY BEEN IMPLICATED IN INFERTILITY. HERE, WE REPORT A REDUCTION OF HISTONE DEACETYLASE 3 (HDAC3) PROTEIN AMOUNTS IN EUTOPIC ENDOMETRIUM OF INFERTILE WOMEN WITH ENDOMETRIOSIS COMPARED TO A CONTROL GROUP. TO INVESTIGATE THE EFFECT OF HDAC3 LOSS IN THE UTERUS, WE GENERATED MICE WITH CONDITIONAL ABLATION OF HDAC3 IN PROGESTERONE RECEPTOR (PGR)-POSITIVE CELLS (PGR(CRE/+)HDAC3(F/F) ; HDAC3(D/D) ). LOSS OF HDAC3 IN THE UTERUS OF MICE RESULTS IN INFERTILITY DUE TO IMPLANTATION FAILURE AND DECIDUALIZATION DEFECT. EXPRESSION MICROARRAY AND CHIP-SEQ ANALYSES IDENTIFIED COL1A1 AND COL1A2 AS DIRECT TARGETS OF HDAC3 IN BOTH MICE AND HUMANS. REDUCTION OF HDAC3 ABROGATED DECIDUALIZATION IN A PRIMARY CULTURE OF HUMAN ENDOMETRIAL STROMAL CELLS (HESCS) SIMILAR TO THAT OBSERVED IN INFERTILE PATIENTS WITH ENDOMETRIOSIS. WHEREAS ATTENUATION OF HDAC3 RESULTED IN P300 RECRUITMENT TO COL1A1 AND COL1A2 GENES IN THE UTERUS OF MICE AS WELL AS HESCS, INHIBITION OF P300 PERMITTED HESCS TO UNDERGO DECIDUALIZATION. COLLECTIVELY, WE FOUND ATTENUATION OF HDAC3 AND OVEREXPRESSION OF COLLAGEN TYPE I IN THE EUTOPIC ENDOMETRIUM OF INFERTILE PATIENTS WITH ENDOMETRIOSIS. HDAC3 LOSS CAUSED A DEFECT OF DECIDUALIZATION THROUGH THE ABERRANT TRANSCRIPTIONAL ACTIVATION OF COL1A1 AND COL1A2 GENES IN MICE AND COL1A1 AND COL1A2 GENES IN HUMANS. OUR RESULTS SUGGEST THAT HDAC3 IS CRITICAL FOR ENDOMETRIAL RECEPTIVITY AND DECIDUALIZATION. 2019 18 4224 27 METHYLATION CHANGES IN MUSCLE AND LIVER TISSUES OF MALE AND FEMALE MICE EXPOSED TO ACUTE AND CHRONIC LOW-DOSE X-RAY-IRRADIATION. THE BIOLOGICAL AND GENETIC EFFECTS OF CHRONIC LOW-DOSE RADIATION (LDR) EXPOSURE AND ITS RELATIONSHIP TO CARCINOGENESIS HAVE RECEIVED A LOT OF ATTENTION IN THE RECENT YEARS. FOR EXAMPLE, RADIATION-INDUCED GENOME INSTABILITY, WHICH IS THOUGHT TO BE A PRECURSOR OF TUMOROGENESIS, WAS SHOWN TO HAVE A TRANSGENERATIONAL NATURE. THIS INDICATES A POSSIBLE INVOLVEMENT OF EPIGENETIC MECHANISMS IN LDR-INDUCED GENOME INSTABILITY. GENOMIC DNA METHYLATION IS ONE OF THE MOST IMPORTANT EPIGENETIC MECHANISMS. EXISTING DATA ON RADIATION EFFECTS ON DNA METHYLATION PATTERNS IS LIMITED, AND NO ONE HAS SPECIFICALLY STUDIED THE EFFECTS OF THE LDR. WE REPORT THE FIRST STUDY OF THE EFFECTS OF WHOLE-BODY LDR EXPOSURE ON GLOBAL GENOME METHYLATION IN MUSCLE AND LIVER TISSUES OF MALE AND FEMALE MICE. IN PARALLEL, WE EVALUATED CHANGES IN PROMOTER METHYLATION AND EXPRESSION OF THE TUMOR SUPPRESSOR GENE P16(INKA) AND DNA REPAIR GENE O(6)-METHYLGUANINE-DNA METHYLTRANSFERASE (MGMT). WE OBSERVED DIFFERENT PATTERNS OF RADIATION-INDUCED GLOBAL GENOME DNA METHYLATION IN THE LIVER AND MUSCLE OF EXPOSED MALES AND FEMALES. WE ALSO FOUND SEX AND TISSUE-SPECIFIC DIFFERENCES IN P16(INKA) PROMOTER METHYLATION UPON LDR EXPOSURE. IN MALE LIVER TISSUE, P16(INKA) PROMOTER METHYLATION WAS MORE PRONOUNCED THAN IN FEMALE TISSUE. IN CONTRAST, NO SIGNIFICANT RADIATION-INDUCED CHANGES IN P16(INKA) PROMOTER METHYLATION WERE NOTED IN THE MUSCLE TISSUE OF EXPOSED MALES AND FEMALES. RADIATION ALSO DID NOT SIGNIFICANTLY AFFECT METHYLATION STATUS OF MGMT PROMOTER. WE ALSO OBSERVED SUBSTANTIAL SEX DIFFERENCES IN ACUTE AND CHRONIC RADIATION-INDUCED EXPRESSION OF P16(INKA) AND MGMT GENES. ANOTHER IMPORTANT OUTCOME OF OUR STUDY WAS THE FACT THAT CHRONIC LOW-DOSE RADIATION EXPOSURE PROVED TO BE A MORE POTENT INDUCER OF EPIGENETIC EFFECTS THAN THE ACUTE EXPOSURE. THIS SUPPORTS PREVIOUS FINDINGS THAT CHRONIC EXPOSURE LEADS TO GREATER GENOME DESTABILIZATION THAN ACUTE EXPOSURE. 2004 19 872 28 CHRONIC ALCOHOL EXPOSURE DIFFERENTIALLY ALTERS ONE-CARBON METABOLISM IN RAT LIVER AND BRAIN. BACKGROUND: EPIGENETIC MECHANISMS SUCH AS DNA METHYLATION PLAY AN IMPORTANT ROLE IN REGULATING THE PATHOPHYSIOLOGY OF ALCOHOLISM. CHRONIC ALCOHOL EXPOSURE LEADS TO BEHAVIORAL CHANGES AS WELL AS DECREASED EXPRESSION OF GENES ASSOCIATED WITH SYNAPTIC PLASTICITY. IN THE LIVER, IT HAS BEEN DOCUMENTED THAT CHRONIC ALCOHOL EXPOSURE IMPAIRS METHIONINE SYNTHASE (MS) ACTIVITY LEADING TO A DECREASE IN S-ADENOSYL METHIONINE/S-ADENOSYL HOMOCYSTEINE (SAM/SAH) RATIO WHICH RESULTS IN DNA HYPOMETHYLATION; HOWEVER, IT IS NOT KNOWN WHETHER SIMILAR ALTERATIONS OF SAM AND SAH LEVELS ARE ALSO PRODUCED IN BRAIN. METHODS: MALE ADULT SPRAGUE DAWLEY RATS WERE FED CHRONICALLY WITH LIEBER-DECARLI ETHANOL (ETOH) (9% V/V) OR CONTROL DIET. THE ETOH-DIET-FED RATS WERE WITHDRAWN FOR 0 AND 24 HOURS. THE CEREBELLUM AND LIVER TISSUES WERE DISSECTED AND USED TO INVESTIGATE CHANGES IN ONE-CARBON METABOLISM, SAM, AND SAH LEVELS. RESULTS: WE FOUND THAT CHRONIC ETOH EXPOSURE DECREASED SAM LEVELS, SAM/SAH RATIO, MS, METHYLENE TETRAHYDROFOLATE REDUCTASE, AND BETAINE HOMOCYSTEINE METHYLTRANSFERASE (BHMT) EXPRESSION AND INCREASED METHIONINE ADENOSYLTRANSFERASE-2B (MAT2B) BUT NOT MAT2A EXPRESSION IN THE LIVER. IN CONTRAST, CHRONIC ETOH EXPOSURE DECREASED SAH LEVELS, INCREASED SAM/SAH RATIO AND THE EXPRESSION OF MAT2A AND S-ADENOSYL HOMOCYSTEINE HYDROLASE, WHILE THE LEVELS OF SAM OR BHMT EXPRESSION IN CEREBELLUM REMAINED UNALTERED. HOWEVER, IN BOTH LIVER AND CEREBELLUM, CHRONIC ETOH EXPOSURE DECREASED THE EXPRESSION OF MS AND INCREASED MAT2B EXPRESSION. ALL CHRONIC ETOH-INDUCED CHANGES OF ONE-CARBON METABOLISM IN CEREBELLUM, BUT NOT LIVER, RETURNED TO NEAR-NORMAL LEVELS DURING ETOH WITHDRAWAL. CONCLUSIONS: THESE RESULTS INDICATE A DECREASED "METHYLATION INDEX" IN LIVER AND AN INCREASED "METHYLATION INDEX" IN CEREBELLUM. THE OPPOSING CHANGES OF THE "METHYLATION INDEX" SUGGEST ALTERED DNA METHYLATION IN LIVER AND CEREBELLUM, THUS IMPLICATING ONE-CARBON METABOLISM IN THE PATHOPHYSIOLOGY OF ALCOHOLISM. 2017 20 513 19 ASSOCIATION OF SEROTONIN TRANSPORTER GENE ALUJB METHYLATION WITH MAJOR DEPRESSION, AMYGDALA RESPONSIVENESS, 5-HTTLPR/RS25531 POLYMORPHISM, AND STRESS. DNA METHYLATION PROFILES OF THE SEROTONIN TRANSPORTER GENE (SLC6A4) HAVE BEEN SHOWN TO ALTER SLC6A4 EXPRESSION, DRIVE ANTIDEPRESSANT TREATMENT RESPONSE AND MODIFY BRAIN FUNCTIONS. THIS STUDY INVESTIGATED WHETHER METHYLATION OF AN ALUJB ELEMENT IN THE SLC6A4 PROMOTOR WAS ASSOCIATED WITH MAJOR DEPRESSIVE DISORDER (MDD), AMYGDALA REACTIVITY TO EMOTIONAL FACES, 5-HTTLPR/RS25531 POLYMORPHISM, AND RECENT STRESS. MDD PATIENTS (N=122) AND HEALTHY CONTROLS (HC, N=176) UNDERWENT FMRI DURING AN EMOTIONAL FACE-MATCHING TASK. INDIVIDUAL SLC6A4 ALUJB METHYLATION PROFILES WERE ASCERTAINED AND ASSOCIATED WITH MDD, AMYGDALA REACTIVITY, 5-HTTLPR/RS25531, AND STRESS. SLC6A4 ALUJB METHYLATION WAS SIGNIFICANTLY LOWER IN MDD COMPARED TO HC AND IN STRESSED COMPARED TO LESS STRESSED PARTICIPANTS. LOWER ALUJB METHYLATION WAS PARTICULARLY FOUND IN 5-HTTLPR/RS25531 RISK ALLELE CARRIERS UNDER STRESS AND CORRELATED WITH LESS DEPRESSIVE EPISODES. FMRI ANALYSIS REVEALED A SIGNIFICANT INTERACTION OF ALUJB METHYLATION AND DIAGNOSIS IN THE AMYGDALA, WITH MDD PATIENTS SHOWING LOWER ALUJB METHYLATION ASSOCIATED WITH DECREASED AMYGDALA REACTIVITY. WHILE NO JOINT EFFECT OF ALUJB METHYLATION AND 5-HTTLPR/RS25531 EXISTED, RISK ALLELE CARRIERS SHOWED SIGNIFICANTLY INCREASED BILATERAL AMYGDALA ACTIVATION. THESE FINDINGS SUGGEST A ROLE OF SLC6A4 ALUJB METHYLATION IN MDD, AMYGDALA REACTIVITY, AND STRESS REACTION, PARTLY INTERWOVEN WITH 5-HTTLPR/RS25531 EFFECTS. PATIENTS WITH LOW METHYLATION IN CONJUNCTION WITH A SHORTER MDD HISTORY AND DECREASED AMYGDALA REACTIVITY MIGHT FEATURE A MORE STRESS-ADAPTIVE EPIGENETIC PROCESS, MAYBE VIA THEORETICALLY POSSIBLE ENDOGENOUS ANTIDEPRESSANT-LIKE EFFECTS. IN CONTRAST, PATIENTS WITH HIGHER METHYLATION MIGHT POSSIBLY SUFFER FROM IMPAIRED EPIGENETIC ADAPTION TO CHRONIC STRESS. FURTHER, THE 5-HTTLPR/RS25531 ASSOCIATION WITH AMYGDALA ACTIVATION WAS CONFIRMED IN OUR LARGE SAMPLE. 2018