1 6681 136 USING ZEBRAFISH EMBRYO BIOASSAYS TO IDENTIFY CHEMICALS MODULATING THE REGULATION OF THE EPIGENOME: A CASE STUDY WITH SIMVASTATIN. CONTAMINANTS OF EMERGING CONCERN HAVE BEEN INCREASINGLY ASSOCIATED WITH THE MODULATION OF THE EPIGENOME, LEADING TO POTENTIALLY INHERITED AND PERSISTENT IMPACTS ON APICAL ENDPOINTS. HERE, WE ADDRESS THE PERFORMANCE OF THE OECD TEST NO. 236 FET (FISH EMBRYO ACUTE TOXICITY) IN THE IDENTIFICATION OF CHEMICALS ABLE TO MODULATE THE EPIGENOME. USING ZEBRAFISH (DANIO RERIO) EMBRYOS, ACUTE AND CHRONIC EXPOSURES WERE PERFORMED WITH THE PHARMACEUTICAL, SIMVASTATIN (SIM), A WIDELY PRESCRIBED HYPOCHOLESTEROLEMIC DRUG REPORTED TO INDUCE INTER AND TRANSGENERATIONAL EFFECTS. IN THE PRESENT STUDY, THE EPIGENETIC EFFECTS OF ENVIRONMENTALLY RELEVANT CONCENTRATIONS OF SIM (FROM 8 NG/L TO 2000 NG/L) WERE ADDRESSED FOLLOWING (1) AN ACUTE EMBRYO ASSAY BASED ON OECD TEST NO. 236 FET, (2) A CHRONIC PARTIAL LIFE-CYCLE EXPOSURE USING ADULT ZEBRAFISH (90 DAYS), AND (3) F1 EMBRYOS OBTAINED FROM PARENTAL EXPOSED ANIMALS. SIMVASTATIN INDUCED SIGNIFICANT EFFECTS IN GENE EXPRESSION OF KEY EPIGENETIC BIOMARKERS (DNA METHYLATION AND HISTONE ACETYLATION/DEACETYLATION) IN THE GONADS OF EXPOSED ADULT ZEBRAFISH AND IN 80 HPF ZEBRAFISH EMBRYOS (ACUTE AND CHRONIC PARENTAL INTERGENERATIONAL EXPOSURE), ALBEIT WITH DISTINCT EFFECT PROFILES BETWEEN BIOLOGICAL SAMPLES. IN THE CHRONIC EXPOSURE, SIM IMPACTED PARTICULARLY DNA METHYLTRANSFERASE GENES IN MALES AND FEMALE GONADS, WHEREAS IN F1 EMBRYOS SIM AFFECTED MOSTLY GENES ASSOCIATED WITH HISTONE ACETYLATION/DEACETYLATION. IN THE EMBRYO ACUTE DIRECT EXPOSURE, SIM MODULATED THE EXPRESSION OF BOTH GENES INVOLVED IN DNA METHYLATION AND HISTONE DEACETYLASE. THESE FINDINGS FURTHER SUPPORT THE USE OF EPIGENETIC BIOMARKERS IN ZEBRAFISH EMBRYOS IN A HIGH THROUGHPUT APPROACH TO IDENTIFY AND PRIORITIZE EPIGENOME-MODULATING CHEMICALS. 2023 2 3835 33 IONISING RADIATION INDUCES PROMOTER DNA HYPOMETHYLATION AND PERTURBS TRANSCRIPTIONAL ACTIVITY OF GENES INVOLVED IN MORPHOGENESIS DURING GASTRULATION IN ZEBRAFISH. EMBRYONIC DEVELOPMENT IS PARTICULARLY VULNERABLE TO STRESS AND DNA DAMAGE, AS MUTATIONS CAN ACCUMULATE THROUGH CELL PROLIFERATION IN A WIDE NUMBER OF CELLS AND ORGANS. HOWEVER, THE BIOLOGICAL EFFECTS OF CHRONIC EXPOSURE TO IONISING RADIATION (IR) AT LOW AND MODERATE DOSE RATES (< 6 MGY/H) REMAIN LARGELY CONTROVERSIAL, RAISING CONCERNS FOR ENVIRONMENTAL PROTECTION. THE PRESENT STUDY FOCUSES ON THE MOLECULAR EFFECTS OF IR (0.005 TO 50 MGY/H) ON ZEBRAFISH EMBRYOS AT THE GASTRULA STAGE (6 HPF), AT BOTH THE TRANSCRIPTOMICS AND EPIGENETICS LEVELS. OUR RESULTS SHOW THAT EXPOSURE TO IR MODIFIES THE EXPRESSION OF GENES INVOLVED IN MITOCHONDRIAL ACTIVITY FROM 0.5 TO 50 MGY/H. IN ADDITION, IMPORTANT DEVELOPMENTAL PATHWAYS, NAMELY, THE NOTCH, RETINOIC ACID, BMP AND WNT SIGNALLING PATHWAYS, WERE ALTERED AT 5 AND 50 MGY/H. TRANSCRIPTIONAL CHANGES OF GENES INVOLVED IN THE MORPHOGENESIS OF THE ECTODERM AND MESODERM WERE DETECTED AT ALL DOSE RATES, BUT WERE PROMINENT FROM 0.5 TO 50 MGY/H. AT THE EPIGENETIC LEVEL, EXPOSURE TO IR INDUCED A HYPOMETHYLATION OF DNA IN THE PROMOTER OF GENES THAT COLOCALISED WITH BOTH H3K27ME3 AND H3KME4 HISTONE MARKS AND CORRELATED WITH CHANGES IN TRANSCRIPTIONAL ACTIVITY. FINALLY, PATHWAY ENRICHMENT ANALYSIS DEMONSTRATED THAT THE DNA METHYLATION CHANGES OCCURRED IN THE PROMOTER OF IMPORTANT DEVELOPMENTAL GENES, INCLUDING MORPHOGENESIS OF THE ECTODERM AND MESODERM. TOGETHER, THESE RESULTS SHOW THAT THE TRANSCRIPTIONAL PROGRAM REGULATING MORPHOGENESIS IN GASTRULATING EMBRYOS WAS MODIFIED AT DOSE RATES GREATER THAN OR EQUAL TO 0.5 MGY/H, WHICH MIGHT PREDICT POTENTIAL NEUROGENESIS AND SOMITOGENESIS DEFECTS OBSERVED AT SIMILAR DOSE RATES LATER IN DEVELOPMENT. 2020 3 6078 28 THE EFFECT OF CHRONIC ARSENIC EXPOSURE IN ZEBRAFISH. ARSENIC IS A PREVALENT ENVIRONMENTAL TOXIN AND A GROUP ONE HUMAN CARCINOGENIC AGENT. CHRONIC ARSENIC EXPOSURE HAS BEEN ASSOCIATED WITH MANY HUMAN DISEASES. THE AIM OF THIS STUDY IS TO EVALUATE ZEBRAFISH AS AN ANIMAL MODEL TO ASSESS ARSENIC TOXICITY IN ELEVATED LONG-TERM ARSENIC EXPOSURE. WITH PROLONGED EXPOSURE (6 MONTHS) TO VARIOUS CONCENTRATIONS OF ARSENIC FROM 50 PPB TO 300 PPB, EFFECTS OF ARSENIC ACCUMULATION IN ZEBRAFISH TISSUES, AND PHENOTYPES WERE INVESTIGATED. RESULTS SHOWED THAT THERE ARE NO SIGNIFICANT CHANGES OF ARSENIC RETENTION IN ZEBRAFISH TISSUES, AND ZEBRAFISH DID NOT EXHIBIT ANY VISIBLE TUMOR FORMATION UNDER ARSENIC EXPOSURE CONDITIONS. HOWEVER, THE ZEBRAFISH DEMONSTRATE A DYSFUNCTION IN THEIR NEUROLOGICAL SYSTEM, WHICH IS REFLECTED BY A REDUCTION OF LOCOMOTIVE ACTIVITY. MOREOVER, ELEVATED LEVELS OF THE SUPEROXIDE DISMUTASE (SOD2) PROTEIN WERE DETECTED IN THE EYE AND LIVER, SUGGESTING INCREASED OXIDATIVE STRESS. IN ADDITION, THE PROGENIES OF ARSENIC-TREATED PARENTS DISPLAYED A SMALLER BIOMASS (FOUR-FOLD REDUCTION IN BODY WEIGHT) COMPARED WITH THOSE FROM THEIR PARENTAL CONTROLS. THIS RESULT INDICATES THAT ARSENIC MAY INDUCE GENETIC OR EPIGENETIC CHANGES THAT ARE THEN PASSED ON TO THE NEXT GENERATION. OVERALL, THIS STUDY DEMONSTRATES THAT ZEBRAFISH IS A CONVENIENT VERTEBRATE MODEL WITH ADVANTAGES IN THE EVALUATION OF ARSENIC-ASSOCIATED NEUROLOGICAL DISORDERS AS WELL AS ITS INFLUENCES ON THE OFFSPRING. 2016 4 4008 31 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 5 73 34 A MULTI-GENERATIONAL STUDY ON LOW-DOSE BPA EXPOSURE IN WISTAR RATS: EFFECTS ON MATERNAL BEHAVIOR, FLAVOR INTAKE AND DEVELOPMENT. BISPHENOL A (BPA) IS A COMMON ENDOCRINE DISRUPTOR FOUND AS AN ENVIRONMENTAL AND FOOD CONTAMINANT. IT EXERTS BOTH DEVELOPMENTAL AND BEHAVIORAL EFFECTS, MAINLY WHEN EXPOSURE OCCURS IN EARLY LIFE. THE AIM OF THIS STUDY WAS TO DETERMINE THE MULTI-GENERATIONAL EFFECTS OF CHRONIC, HUMAN-RELEVANT LOW-DOSE EXPOSURE TO BPA ON DEVELOPMENT, MATERNAL BEHAVIOR AND FLAVOR PREFERENCE IN WISTAR RATS. BPA WAS ORALLY ADMINISTERED AT A DAILY DOSE OF 5 MUG/KG BODY WEIGHT TO F0 PREGNANT DAMS FROM THE FIRST DAY OF GESTATION (GD 1) UNTIL THE LAST DAY OF LACTATION (LD 21), AND THEN TO F1 OFFSPRING FROM WEANING (PND 21) TO ADULTHOOD (PND 100). F2 OFFSPRING WERE NOT EXPOSED. DEVELOPMENT AND CLINICAL SIGNS OF TOXICITY WERE ASSESSED DAILY. MATERNAL BEHAVIOR WAS EVALUATED BY OBSERVING NURSING AND PUP-CARING ACTIONS, AS WELL AS "NON-MATERNAL" BEHAVIORS IN F0 AND F1 DAMS FROM PARTURITION UNTIL LD 8. THE FLAVOR PREFERENCES OF F1 AND F2 OFFSPRING WERE EVALUATED BASED ON THE INTAKE OF SWEET, SALT AND FAT SOLUTIONS USING THE TWO-BOTTLE CHOICE TEST ON PND 21-34 AND PND 86-99. BPA EXPOSURE: 1) DECREASED MATERNAL BEHAVIOR IN F1 DAMS, 2) CAUSED DEVELOPMENTAL DEFECTS IN BOTH F1 AND F2 OFFSPRING, WITH A NOTICEABLE DECREASE IN ANOGENITAL DISTANCE IN MALE RATS, AND 3) DID NOT AFFECT FLAVORED SOLUTION INTAKE IN F1, BUT INDUCED CHANGES IN SWEET PREFERENCE IN F2 JUVENILES AND IN SALT AND FAT SOLUTION INTAKES IN F2 ADULTS, AND 4) INDUCED A BODY WEIGHT INCREASE IN THE F2 GENERATION ONLY, WHEREAS FOOD INTAKE AND WATER CONSUMPTION DID NOT CHANGE. TAKEN AS A WHOLE, OUR FINDINGS SHOWED THAT BOTH GESTATIONAL (F0) AND LIFELONG (F1) EXPOSURES TO A HUMAN-RELEVANT DOSE OF BPA COULD INDUCE MULTI-GENERATIONAL EFFECTS ON BOTH DEVELOPMENT AND BEHAVIOR. THESE RESULTS SUGGEST POSSIBLE SELECTIVE NEUROENDOCRINE DEFECTS AND/OR EPIGENETIC CHANGES CAUSED BY BPA EXPOSURE. 2014 6 4875 30 OVEREXPRESSION OF AKT1 ENHANCES ADIPOGENESIS AND LEADS TO LIPOMA FORMATION IN ZEBRAFISH. BACKGROUND: OBESITY IS A COMPLEX, MULTIFACTORIAL DISORDER INFLUENCED BY THE INTERACTION OF GENETIC, EPIGENETIC, AND ENVIRONMENTAL FACTORS. OBESITY INCREASES THE RISK OF CONTRACTING MANY CHRONIC DISEASES OR METABOLIC SYNDROME. RESEARCHERS HAVE ESTABLISHED SEVERAL MAMMALIAN MODELS OF OBESITY TO STUDY ITS UNDERLYING MECHANISM. HOWEVER, A LOWER VERTEBRATE MODEL FOR CONVENIENTLY PERFORMING DRUG SCREENING AGAINST OBESITY REMAINS ELUSIVE. THE SPECIFIC AIM OF THIS STUDY WAS TO CREATE A ZEBRAFISH OBESITY MODEL BY OVER EXPRESSING THE INSULIN SIGNALING HUB OF THE AKT1 GENE. METHODOLOGY/PRINCIPAL FINDINGS: SKIN ONCOGENIC TRANSFORMATION SCREENING SHOWS THAT A STABLE ZEBRAFISH TRANSGENIC OF TG(KRT4HSA.MYRAKT1)(CY18) DISPLAYS SEVERELY OBESE PHENOTYPES AT THE ADULT STAGE. IN TG(KRT4:HSA.MYRAKT1)(CY18), THE EXPRESSION OF EXOGENOUS HUMAN CONSTITUTIVELY ACTIVE AKT1 (MYRAKT1) CAN ACTIVATE ENDOGENOUS DOWNSTREAM TARGETS OF MTOR, GSK-3ALPHA/BETA, AND 70S6K. DURING THE EMBRYONIC TO LARVAL TRANSITORY PHASE, THE SPECIFIC OVER EXPRESSION OF MYRAKT1 IN SKIN CAN PROMOTE HYPERTROPHIC AND HYPERPLASTIC GROWTH. FROM 21 HOUR POST-FERTILIZATION (HPF) ONWARDS, MYRAKT1 TRANSGENE WAS ECTOPICALLY EXPRESSED IN SEVERAL MESENCHYMAL DERIVED TISSUES. THIS MAY BE THE RESULT OF THE INTEGRATION POSITION EFFECT. TG(KRT4:HSA.MYRAKT1)(CY18) CAUSED A RAPID INCREASE OF BODY WEIGHT, HYPERPLASTIC GROWTH OF ADIPOCYTES, ABNORMAL ACCUMULATION OF FAT TISSUES, AND BLOOD GLUCOSE INTOLERANCE AT THE ADULT STAGE. REAL-TIME RT-PCR ANALYSIS SHOWED THE MAJORITY OF KEY GENES ON REGULATING ADIPOGENESIS, ADIPOCYTOKINE, AND INFLAMMATION ARE HIGHLY UPREGULATED IN TG(KRT4:HSA.MYRAKT1)(CY18). IN CONTRAST, THE MYOGENESIS- AND SKELETOGENESIS-RELATED GENE TRANSCRIPTS ARE SIGNIFICANTLY DOWNREGULATED IN TG(KRT4:HSA.MYRAKT1)(CY18), SUGGESTING THAT EXCESS ADIPOCYTE DIFFERENTIATION OCCURS AT THE EXPENSE OF OTHER MESENCHYMAL DERIVED TISSUES. CONCLUSION/SIGNIFICANCE: COLLECTIVELY, THE FINDINGS OF THIS STUDY PROVIDE DIRECT EVIDENCE THAT AKT1 SIGNALING PLAYS AN IMPORTANT ROLE IN BALANCING NORMAL LEVELS OF FAT TISSUE IN VIVO. THE OBESE ZEBRAFISH EXAMINED IN THIS STUDY COULD BE A NEW POWERFUL MODEL TO SCREEN NOVEL DRUGS FOR THE TREATMENT OF HUMAN OBESITY. 2012 7 891 40 CHRONIC EFFECTS OF CLOFIBRIC ACID IN ZEBRAFISH (DANIO RERIO): A MULTIGENERATIONAL STUDY. CLOFIBRIC ACID (CA) IS AN ACTIVE METABOLITE OF THE BLOOD LIPID LOWERING AGENT CLOFIBRATE, A PHARMACEUTICAL DESIGNED TO WORK AS AGONIST OF PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR ALPHA (PPARA). IT IS THE MOST COMMONLY REPORTED FIBRATE IN AQUATIC ENVIRONMENTS WITH LOW DEGRADATION RATE AND POTENTIAL ENVIRONMENTAL PERSISTENCE. PREVIOUS FISH EXPOSURES SHOWED THAT CA MAY IMPACT SPERMATOGENESIS, GROWTH AND THE EXPRESSION OF FAT BINDING PROTEIN GENES. HOWEVER, THERE ARE LIMITED DATA ON THE EFFECTS OF CHRONIC MULTIGENERATIONAL CA EXPOSURES. HERE, WE ASSESSED CHRONIC MULTIGENERATIONAL EFFECTS OF CA EXPOSURE USING ZEBRAFISH (DANIO RERIO) AS A TELEOST MODEL. ZEBRAFISH WERE EXPOSED THROUGH THE DIET TO CA (1 AND 10MG/G) DURING THEIR WHOLE LIFETIME. GROWTH, REPRODUCTION-RELATED PARAMETERS AND EMBRYONIC DEVELOPMENT WERE ASSESSED IN THE EXPOSED FISH (F1 GENERATION) AND THEIR OFFSPRING (F2 GENERATION), TOGETHER WITH MUSCLE TRIGLYCERIDE CONTENT AND GONAD HISTOLOGY. IN ORDER TO STUDY THE POTENTIAL UNDERLYING MECHANISMS, THE TRANSCRIPTION LEVELS OF GENES CODING FOR ENZYMES INVOLVED IN LIPID METABOLISM PATHWAYS WERE DETERMINED. THE RESULTS SHOW THAT CHRONIC LIFE-CYCLE EXPOSURE TO CA INDUCED A SIGNIFICANT REDUCTION IN GROWTH OF F1 GENERATION AND LOWERED TRIGLYCERIDE MUSCLE CONTENT (10MG/G GROUP). ALSO, AN IMPACT IN MALE GONAD DEVELOPMENT WAS OBSERVED TOGETHER WITH A DECREASE IN THE FECUNDITY (10MG/G GROUP) AND HIGHER FREQUENCY OF EMBRYO ABNORMALITIES IN THE OFFSPRING OF FISH EXPOSED TO THE LOWEST CA DOSE. THE PROFILE OF THE TARGET GENES WAS SEX- AND TISSUE-DEPENDENT. IN F1 AN UP-REGULATION OF MALE HEPATIC PPARAA, PPARB AND ACOX TRANSCRIPT LEVELS WAS OBSERVED, SUGGESTING AN ACTIVATION OF THE FATTY ACID METABOLISM (PROVIDED THAT TRANSCRIPT LEVEL CHANGE INDICATES ALSO A PROTEIN LEVEL CHANGE). INTERESTINGLY, THE F2 GENERATION, RAISED WITH CONTROL DIET, DISPLAYED A RESPONSE PATTERN DIFFERENT FROM THAT OBSERVED IN F1, SHOWING AN INCREASE IN WEIGHT IN THE DESCENDANTS OF CA EXPOSED FISH, IN COMPARISON WITH CONTROL ANIMALS, WHICH POINTS TO A MULTIGENERATIONAL EFFECT. 2015 8 701 25 BROWN FAT DNMT3B DEFICIENCY AMELIORATES OBESITY IN FEMALE MICE. OBESITY RESULTS FROM A CHRONIC ENERGY IMBALANCE DUE TO ENERGY INTAKE EXCEEDING ENERGY EXPENDITURE. ACTIVATION OF BROWN FAT THERMOGENESIS HAS BEEN SHOWN TO COMBAT OBESITY. EPIGENETIC REGULATION, INCLUDING DNA METHYLATION, HAS EMERGED AS A KEY REGULATOR OF BROWN FAT THERMOGENIC FUNCTION. HERE WE AIMED TO STUDY THE ROLE OF DNMT3B, A DNA METHYLTRANSFERASE INVOLVED IN DE NOVO DNA METHYLATION, IN THE REGULATION OF BROWN FAT THERMOGENESIS AND OBESITY. WE FOUND THAT THE SPECIFIC DELETION OF DNMT3B IN BROWN FAT PROMOTES THE THERMOGENIC AND MITOCHONDRIAL PROGRAM IN BROWN FAT, ENHANCES ENERGY EXPENDITURE, AND DECREASES ADIPOSITY IN FEMALE MICE FED A REGULAR CHOW DIET. WITH A LEAN PHENOTYPE, THE FEMALE KNOCKOUT MICE ALSO EXHIBIT INCREASED INSULIN SENSITIVITY. IN ADDITION, DNMT3B DEFICIENCY IN BROWN FAT ALSO PREVENTS DIET-INDUCED OBESITY AND INSULIN RESISTANCE IN FEMALE MICE. INTERESTINGLY, OUR RNA-SEQ ANALYSIS REVEALED AN UPREGULATION OF THE PI3K-AKT PATHWAY IN THE BROWN FAT OF FEMALE DNMT3B KNOCKOUT MICE. HOWEVER, MALE DNMT3B KNOCKOUT MICE HAVE NO CHANGE IN THEIR BODY WEIGHT, SUGGESTING THE EXISTENCE OF SEXUAL DIMORPHISM IN THE BROWN FAT DNMT3B KNOCKOUT MODEL. OUR DATA DEMONSTRATE THAT DNMT3B PLAYS AN IMPORTANT ROLE IN THE REGULATION OF BROWN FAT FUNCTION, ENERGY METABOLISM AND OBESITY IN FEMALE MICE. 2021 9 6280 35 THE PLASTICIZER BISPHENOL A PERTURBS THE HEPATIC EPIGENOME: A SYSTEMS LEVEL ANALYSIS OF THE MIRNOME. UBIQUITOUS EXPOSURE TO BISPHENOL A (BPA), AN ENDOCRINE DISRUPTOR (ED), HAS RAISED CONCERNS FOR BOTH HUMAN AND ECOSYSTEM HEALTH. EPIGENETIC FACTORS, INCLUDING MICRORNAS (MIRNAS), ARE KEY REGULATORS OF GENE EXPRESSION DURING CANCER. THE EFFECT OF BPA EXPOSURE ON THE ZEBRAFISH EPIGENOME REMAINS POORLY CHARACTERIZED. ZEBRAFISH REPRESENTS AN EXCELLENT MODEL TO STUDY CANCER AS THE ORGANISM DEVELOPS A DISEASE THAT RESEMBLES HUMAN CANCER. USING ZEBRAFISH AS A SYSTEMS TOXICOLOGY MODEL, WE HYPOTHESIZED THAT CHRONIC BPA-EXPOSURE IMPACTS THE MIRNOME IN ADULT ZEBRAFISH AND ESTABLISHES AN EPIGENOME MORE SUSCEPTIBLE TO CANCER DEVELOPMENT. AFTER A 3 WEEK EXPOSURE TO 100 NM BPA, RNA FROM THE LIVER WAS EXTRACTED TO PERFORM HIGH THROUGHPUT MRNA AND MIRNA SEQUENCING. DIFFERENTIAL EXPRESSION (DE) ANALYSES COMPARING BPA-EXPOSED TO CONTROL SPECIMENS WERE PERFORMED USING ESTABLISHED BIOINFORMATICS PIPELINES. IN THE BPA-EXPOSED LIVER, 6188 MRNAS AND 15 MIRNAS WERE DIFFERENTLY EXPRESSED (Q 30 NG/ ML), AND LARGE FRACTION OF THEM WERE TAKING SUPPLEMENTS DAILY. CONCLUSIONS THESE RESULTS SUGGESTED THAT LEVEL OF FA INGESTION OF JAPANESE PREGNANT WOMEN IS HIGH FOR SUPPORTING NORMAL FETAL DEVELOPMENT. 2020 19 3410 34 HOXA5 UNDERGOES DYNAMIC DNA METHYLATION AND TRANSCRIPTIONAL REPRESSION IN THE ADIPOSE TISSUE OF MICE EXPOSED TO HIGH-FAT DIET. BACKGROUND/OBJECTIVES: THE GENOMIC BASES OF THE ADIPOSE TISSUE ABNORMALITIES INDUCED BY CHRONIC POSITIVE CALORIE EXCESS HAVE BEEN ONLY PARTIALLY ELUCIDATED. WE ADOPTED A GENOME-WIDE APPROACH TO DIRECTLY TEST WHETHER LONG-TERM HIGH-FAT DIET (HFD) EXPOSURE AFFECTS THE DNA METHYLATION PROFILE OF THE MOUSE ADIPOSE TISSUE AND TO IDENTIFY THE FUNCTIONAL CONSEQUENCES OF THESE CHANGES. SUBJECTS/METHODS: WE HAVE USED EPIDIDYMAL FAT OF MICE FED EITHER HIGH-FAT (HFD) OR REGULAR CHOW (STD) DIET FOR 5 MONTHS AND PERFORMED GENOME-WIDE DNA METHYLATION ANALYSES BY METHYLATED DNA IMMUNOPRECIPITATION SEQUENCING (MEDIP-SEQ). MOUSE HOMEOBOX (HOX) GENE DNA METHYLATION PCR, RT-QPCR AND BISULPHITE SEQUENCING ANALYSES WERE THEN PERFORMED. RESULTS: MICE FED THE HFD PROGRESSIVELY EXPANDED THEIR ADIPOSE MASS ACCOMPANIED BY A SIGNIFICANT DECREASE IN GLUCOSE TOLERANCE (P<0.001) AND INSULIN SENSITIVITY (P<0.05). MEDIP-SEQ DATA ANALYSIS REVEALED A UNIFORM DISTRIBUTION OF DIFFERENTIALLY METHYLATED REGIONS (DMR) THROUGH THE ENTIRE ADIPOCYTE GENOME, WITH A HIGHER NUMBER OF HYPERMETHYLATED REGIONS IN HFD MICE (P<0.005). THIS DIFFERENT METHYLATION PROFILE WAS ACCOMPANIED BY INCREASED EXPRESSION OF THE DNMT3A DNA METHYLTRANSFERASE (DNMT; P<0.05) AND THE METHYL-CPG-BINDING DOMAIN PROTEIN MBD3 (P<0.05) GENES IN HFD MICE. GENE ONTOLOGY ANALYSIS REVEALED THAT, IN THE HFD-TREATED MICE, THE HOX FAMILY OF DEVELOPMENT GENES WAS HIGHLY ENRICHED IN DIFFERENTIALLY METHYLATED GENES (P=0.008). TO VALIDATE THIS FINDING, HOXA5, WHICH IS IMPLICATED IN FAT TISSUE DIFFERENTIATION AND REMODELING, HAS BEEN SELECTED AND ANALYZED BY BISULPHITE SEQUENCING, CONFIRMING HYPERMETHYLATION IN THE ADIPOSE TISSUE FROM THE HFD MICE. HOXA5 HYPERMETHYLATION WAS ASSOCIATED WITH DOWNREGULATION OF HOXA5 MRNA AND PROTEIN EXPRESSION. FEEDING ANIMALS PREVIOUSLY EXPOSED TO THE HFD WITH A STANDARD CHOW DIET FOR TWO FURTHER MONTHS IMPROVED THE METABOLIC PHENOTYPE OF THE ANIMALS, ACCOMPANIED BY RETURN OF HOXA5 METHYLATION AND EXPRESSION LEVELS (P<0.05) TO VALUES SIMILAR TO THOSE OF THE CONTROL MICE MAINTAINED UNDER STANDARD CHOW. CONCLUSIONS: HFD INDUCES ADIPOSE TISSUE ABNORMALITIES ACCOMPANIED BY EPIGENETIC CHANGES AT THE HOXA5 ADIPOSE TISSUE REMODELING GENE. 2016 20 930 28 CHRONIC IRRADIATION OF HUMAN CELLS REDUCES HISTONE LEVELS AND DEREGULATES GENE EXPRESSION. OVER THE PAST DECADES, THERE HAVE BEEN HUGE ADVANCES IN UNDERSTANDING CELLULAR RESPONSES TO IONISING RADIATION (IR) AND DNA DAMAGE. THESE STUDIES, HOWEVER, WERE MOSTLY EXECUTED WITH CELL LINES AND MICE USING SINGLE OR MULTIPLE ACUTE DOSES OF RADIATION. HENCE, RELATIVELY LITTLE IS KNOWN ABOUT HOW CONTINUOUS EXPOSURE TO LOW DOSE IONISING RADIATION AFFECTS NORMAL CELLS AND ORGANISMS, EVEN THOUGH OUR CELLS ARE CONSTANTLY EXPOSED TO LOW LEVELS OF RADIATION. WE ADDRESSED THIS ISSUE BY EXAMINING THE CONSEQUENCES OF EXPOSING HUMAN PRIMARY CELLS TO CONTINUOUS IONISING GAMMA-RADIATION DELIVERED AT 6-20 MGY/H. ALTHOUGH THESE DOSE RATES ARE ESTIMATED TO INFLICT FEWER THAN A SINGLE DNA DOUBLE-STRAND BREAK (DSB) PER HOUR PER CELL, THEY STILL CAUSED DOSE-DEPENDENT REDUCTIONS IN CELL PROLIFERATION AND INCREASED CELLULAR SENESCENCE. WE CONCOMITANTLY OBSERVED HISTONE PROTEIN LEVELS TO REDUCE BY UP TO 40%, WHICH IN CONTRAST TO PREVIOUS OBSERVATIONS, WAS NOT MAINLY DUE TO PROTEIN DEGRADATION BUT INSTEAD CORRELATED WITH REDUCED HISTONE GENE EXPRESSION. HISTONE REDUCTIONS WERE ACCOMPANIED BY ENLARGED NUCLEAR SIZE PARALLELED BY AN INCREASE IN GLOBAL TRANSCRIPTION, INCLUDING THAT OF PRO-INFLAMMATORY GENES. THUS, CHRONIC IRRADIATION, EVEN AT LOW DOSE-RATES, CAN INDUCE CELL SENESCENCE AND ALTER GENE EXPRESSION VIA A HITHERTO UNCHARACTERISED EPIGENETIC ROUTE. THESE FEATURES OF CHRONIC RADIATION REPRESENT A NEW ASPECT OF RADIATION BIOLOGY. 2020