1 4180 150 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 2 3715 39 INHERITED EFFECTS OF LOW-DOSE EXPOSURE TO METHYLMERCURY IN NEURAL STEM CELLS. METHYLMERCURY (MEHG) IS AN ENVIRONMENTAL CONTAMINANT WITH RECOGNIZED NEUROTOXIC EFFECTS, PARTICULARLY TO THE DEVELOPING NERVOUS SYSTEM. IN THE PRESENT STUDY, WE SHOW THAT NANOMOLAR CONCENTRATIONS OF MEHG CAN INDUCE LONG-LASTING EFFECTS IN NEURAL STEM CELLS (NSCS). WE INVESTIGATED SHORT-TERM DIRECT AND LONG-TERM INHERITED EFFECTS OF EXPOSURE TO MEHG (2.5 OR 5.0 NM) USING PRIMARY CULTURES OF RAT EMBRYONIC CORTICAL NSCS. WE FOUND THAT MEHG HAD NO ADVERSE EFFECT ON CELL VIABILITY BUT REDUCED NSC PROLIFERATION AND ALTERED THE EXPRESSION OF CELL CYCLE REGULATORS (P16 AND P21) AND SENESCENCE-ASSOCIATED MARKERS. IN ADDITION, WE DEMONSTRATED A DECREASE IN GLOBAL DNA METHYLATION IN THE EXPOSED CELLS, INDICATING THAT EPIGENETIC CHANGES MAY BE INVOLVED IN THE MECHANISMS UNDERLYING THE MEHG-INDUCED EFFECTS. THESE CHANGES WERE OBSERVED IN CELLS DIRECTLY EXPOSED TO MEHG (PARENT CELLS) AND IN THEIR DAUGHTER CELLS CULTURED UNDER MEHG-FREE CONDITIONS. IN AGREEMENT WITH OUR IN VITRO DATA, A TREND WAS FOUND FOR DECREASED CELL PROLIFERATION IN THE SUBGRANULAR ZONE IN THE HIPPOCAMPI OF ADULT MICE EXPOSED TO LOW DOSES OF MEHG DURING THE PERINATAL PERIOD. INTERESTINGLY, THIS IMPAIRED PROLIFERATION HAD A MEASURABLE IMPACT ON THE TOTAL NUMBER OF NEURONS IN THE HIPPOCAMPAL DENTATE GYRUS. IMPORTANTLY, THIS EFFECT COULD BE REVERSED BY CHRONIC ANTIDEPRESSANT TREATMENT. OUR STUDY PROVIDES NOVEL EVIDENCE FOR PROGRAMMING EFFECTS INDUCED BY MEHG IN NSCS AND SUPPORTS THE IDEA THAT DEVELOPMENTAL EXPOSURE TO LOW LEVELS OF MEHG MAY RESULT IN LONG-TERM CONSEQUENCES PREDISPOSING TO NEURODEVELOPMENTAL DISORDERS AND/OR NEURODEGENERATION. 2012 3 3971 47 LONG-LASTING NEUROTOXIC EFFECTS OF EXPOSURE TO METHYLMERCURY DURING DEVELOPMENT. AMONGST ENVIRONMENTAL CHEMICAL CONTAMINANTS, METHYLMERCURY (MEHG) REMAINS A MAJOR CONCERN BECAUSE OF ITS DETRIMENTAL EFFECTS ON DEVELOPING ORGANISMS, WHICH APPEAR TO BE PARTICULARLY SUSCEPTIBLE TO ITS TOXICITY. HERE, WE INVESTIGATED THE EFFECTS OF LOW MEHG LEVELS ON THE DEVELOPMENT OF THE NERVOUS SYSTEM USING BOTH IN VITRO AND IN VIVO EXPERIMENTAL MODELS. IN NEURAL STEM CELLS (NSCS), MEHG DECREASED PROLIFERATION AND NEURONAL DIFFERENTIATION AND INDUCED CELLULAR SENESCENCE ASSOCIATED WITH IMPAIRMENT IN MITOCHONDRIAL FUNCTION AND A CONCOMITANT DECREASE IN GLOBAL DNA METHYLATION. INTERESTINGLY, THE EFFECTS WERE HERITABLE AND COULD BE OBSERVED IN DAUGHTER NSCS NEVER DIRECTLY EXPOSED TO MEHG. BY CHRONICALLY EXPOSING PREGNANT/LACTATING MICE TO MEHG, WE FOUND PERSISTENT BEHAVIOURAL CHANGES IN THE MALE OFFSPRING, WHICH EXHIBITED DEPRESSION-LIKE BEHAVIOUR THAT COULD BE REVERSED BY CHRONIC TREATMENT WITH THE ANTIDEPRESSANT FLUOXETINE. THE BEHAVIOURAL ALTERATIONS WERE ASSOCIATED WITH A DECREASED NUMBER OF PROLIFERATING CELLS AND LOWER EXPRESSION OF BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) MRNA IN THE HIPPOCAMPAL DENTATE GYRUS. MEHG EXPOSURE ALSO INDUCED LONG-LASTING DNA HYPERMETHYLATION, INCREASED HISTONE H3-K27 TRI-METHYLATION AND DECREASED H3 ACETYLATION AT THE BDNF PROMOTER IV, INDICATING THAT EPIGENETIC MECHANISMS PLAY A CRITICAL ROLE IN MEDIATING THE LONG-LASTING EFFECTS OF PERINATAL EXPOSURE TO MEHG. FLUOXETINE TREATMENT RESTORED THE BDNF MRNA EXPRESSION LEVELS, AS WELL AS THE NUMBER OF PROLIFERATING CELLS IN THE GRANULE CELL LAYER OF THE DENTATE GYRUS, WHICH FURTHER SUPPORTS THE HYPOTHESIS THAT LINKS DEPRESSION TO IMPAIRED NEUROGENESIS. ALTOGETHER, OUR FINDINGS HAVE SHOWN THAT LOW CONCENTRATIONS OF MEHG INDUCE LONG-LASTING EFFECTS IN NSCS THAT CAN POTENTIALLY PREDISPOSE INDIVIDUALS TO DEPRESSION, WHICH WE HAVE REPORTED EARLIER TO OCCUR IN EXPERIMENTAL ANIMALS EXPOSED TO MEHG DURING PRENATAL AND EARLY POSTNATAL DEVELOPMENT. 2013 4 947 41 CHRONIC MEHG EXPOSURE MODIFIES THE HISTONE H3K4ME3 EPIGENETIC LANDSCAPE IN CAENORHABDITIS ELEGANS. METHYLMERCURY (MEHG) IS A PERSISTENT ENVIRONMENTAL POLLUTANT THAT OCCURS IN THE FOOD CHAIN, AT OCCUPATIONAL SITES, AND VIA MEDICAL PROCEDURES. EXPOSURE IN HUMANS AND ANIMAL MODELS RESULTS IN RENAL, NEURO, AND REPRODUCTIVE TOXICITIES. IN THIS STUDY, WE DEMONSTRATE THAT CHRONIC EXPOSURE TO MEHG (10MUM) CAUSES EPIGENETIC LANDSCAPE MODIFICATIONS OF HISTONE H3K4 TRIMETHYLATION (H3K4ME3) MARKS IN CAENORHABDITIS ELEGANS USING CHROMATIN IMMUNO-PRECIPITATION SEQUENCING (CHIP-SEQ). THE MODIFICATIONS CORRESPOND TO THE LOCATIONS OF 1467 GENES WITH ENHANCED AND 508 GENES WITH REDUCED SIGNALS. AMONG ENHANCED GENES ARE THOSE ENCODING GLUTATHIONE-S-TRANSFERASES, LIPOCALIN-RELATED PROTEIN AND A CUTICULAR COLLAGEN. CHIP-SEQ ENHANCEMENT OF THESE GENES WAS CONFIRMED WITH INCREASED MRNA EXPRESSION LEVELS REVEALED BY QRT-PCR. FURTHERMORE, WE OBSERVED ENHANCEMENT OF H3K4ME3 MARKS IN THESE GENES IN ANIMALS EXPOSED TO MEHG IN UTERO AND ASSAYED AT L4 STAGE. IN UTERO EXPOSURE ENHANCED MARKS WITHOUT ALTERATIONS IN MRNA EXPRESSION EXCEPT FOR THE LPR-5 GENE. FINALLY, KNOCKDOWN OF LIPOCALIN-RELATED PROTEIN GENE LPR-5, WHICH IS INVOLVED IN INTERCELLULAR SIGNALING, AND CUTICULAR COLLAGEN GENE DPY-7, STRUCTURAL COMPONENT OF THE CUTICLE, BY RNA INTERFERENCE (RNAI) RESULTED IN INCREASED LETHALITY OF ANIMALS AFTER MEHG EXPOSURE. OUR RESULTS PROVIDE NEW DATA ON THE EPIGENETIC LANDSCAPE CHANGES ELICITED BY MEHG EXPOSURE, AS WELL AS DESCRIBE A UNIQUE MODEL FOR STUDYING IN UTERO EFFECTS OF HEAVY METALS. TOGETHER, THESE FINDINGS MAY HELP TO UNDERSTAND THE TOXICOLOGICAL EFFECTS OF MEHG AT THE MOLECULAR LEVEL. 2017 5 6562 33 TRANSIENT AND PERMANENT CHANGES IN DNA METHYLATION PATTERNS IN INORGANIC ARSENIC-MEDIATED EPITHELIAL-TO-MESENCHYMAL TRANSITION. CHRONIC LOW DOSE INORGANIC ARSENIC EXPOSURE CAUSES CELLS TO TAKE ON AN EPITHELIAL-TO-MESENCHYMAL PHENOTYPE, WHICH IS A CRUCIAL PROCESS IN CARCINOGENESIS. INORGANIC ARSENIC IS NOT A MUTAGEN AND THUS EPIGENETIC ALTERATIONS HAVE BEEN IMPLICATED IN THIS PROCESS. INDEED, DURING THE EPITHELIAL-TO-MESENCHYMAL TRANSITION, MORPHOLOGIC CHANGES TO CELLS CORRELATE WITH CHANGES IN CHROMATIN STRUCTURE AND GENE EXPRESSION, ULTIMATELY DRIVING THIS PROCESS. HOWEVER, STUDIES ON THE EFFECTS OF INORGANIC ARSENIC EXPOSURE/WITHDRAWAL ON THE EPITHELIAL-TO-MESENCHYMAL TRANSITION AND THE IMPACT OF EPIGENETIC ALTERATIONS IN THIS PROCESS ARE LIMITED. IN THIS STUDY WE USED HIGH-RESOLUTION MICROARRAY ANALYSIS TO MEASURE THE CHANGES IN DNA METHYLATION IN CELLS UNDERGOING INORGANIC ARSENIC-INDUCED EPITHELIAL-TO-MESENCHYMAL TRANSITION, AND ON THE REVERSAL OF THIS PROCESS, AFTER REMOVAL OF THE INORGANIC ARSENIC EXPOSURE. WE FOUND THAT CELLS EXPOSED TO CHRONIC, LOW-DOSE INORGANIC ARSENIC EXPOSURE SHOWED 30,530 SITES WERE DIFFERENTIALLY METHYLATED, AND WITH INORGANIC ARSENIC WITHDRAWAL SEVERAL DIFFERENTIAL METHYLATED SITES WERE REVERSED, ALBEIT NOT COMPLETELY. FURTHERMORE, THESE CHANGES IN DNA METHYLATION MAINLY CORRELATED WITH CHANGES IN GENE EXPRESSION AT MOST SITES TESTED BUT NOT AT ALL. THIS STUDY SUGGESTS THAT DNA METHYLATION CHANGES ON GENE EXPRESSION ARE NOT CLEAR-CUT AND PROVIDE A PLATFORM TO BEGIN TO UNCOVER THE RELATIONSHIP BETWEEN DNA METHYLATION AND GENE EXPRESSION, SPECIFICALLY WITHIN THE CONTEXT OF INORGANIC ARSENIC TREATMENT. 2017 6 904 44 CHRONIC EXPOSURE TO CADMIUM INDUCES DIFFERENTIAL METHYLATION IN MICE SPERMATOZOA. CADMIUM EXPOSURE IS UBIQUITOUS AND HAS BEEN LINKED TO DISEASES INCLUDING CANCERS AND REPRODUCTIVE DEFECTS. SINCE CADMIUM IS NONMUTAGENIC, IT IS THOUGHT TO EXERT ITS GENE DYSREGULATORY EFFECTS THROUGH EPIGENETIC REPROGRAMMING. SEVERAL STUDIES HAVE IMPLICATED GERMLINE EXPOSURE TO CADMIUM IN DEVELOPMENTAL REPROGRAMMING. HOWEVER, MOST OF THESE STUDIES HAVE FOCUSED ON MATERNAL EXPOSURE, WHILE THE IMPACT ON SPERM FERTILITY AND DISEASE SUSCEPTIBILITY HAS RECEIVED LESS ATTENTION. IN THIS STUDY, WE USED REDUCED REPRESENTATION BISULFITE SEQUENCING TO COMPREHENSIVELY INVESTIGATE THE IMPACT OF CHRONIC CADMIUM EXPOSURE ON MOUSE SPERMATOZOA DNA METHYLATION. ADULT MALE C57BL/J6 MICE WERE PROVIDED WATER WITH OR WITHOUT CADMIUM CHLORIDE FOR 9 WEEKS. SPERM, TESTES, LIVER, AND KIDNEY TISSUES WERE COLLECTED AT THE END OF THE TREATMENT PERIOD. CADMIUM EXPOSURE WAS CONFIRMED THROUGH GENE EXPRESSION ANALYSIS OF METALLOTHIONEIN-1 AND 2, 2 WELL-KNOWN CADMIUM-INDUCED GENES. ANALYSIS OF SPERM DNA METHYLATION CHANGES REVEALED 1788 DIFFERENTIALLY METHYLATED SITES PRESENT AT REGULATORY REGIONS IN SPERM OF MICE EXPOSED TO CADMIUM COMPARED WITH VEHICLE (CONTROL) MICE. FURTHERMORE, MOST OF THESE DIFFERENTIAL METHYLATION CHANGES POSITIVELY CORRELATED WITH CHANGES IN GENE EXPRESSION AT BOTH THE TRANSCRIPTION INITIATION STAGE AS WELL AS THE SPLICING LEVELS. INTERESTINGLY, THE GENES TARGETED BY CADMIUM EXPOSURE ARE INVOLVED IN SEVERAL CRITICAL DEVELOPMENTAL PROCESSES. OUR RESULTS PRESENT A COMPREHENSIVE ANALYSIS OF THE SPERM METHYLOME IN RESPONSE TO CHRONIC CADMIUM EXPOSURE. THESE DATA, THEREFORE, HIGHLIGHT A FOUNDATIONAL FRAMEWORK TO STUDY GENE EXPRESSION PATTERNS THAT MAY AFFECT FERTILITY IN THE EXPOSED INDIVIDUAL AS WELL AS THEIR OFFSPRING, THROUGH PATERNAL INHERITANCE. 2021 7 3042 39 GENOME-WIDE ALTERATION OF HISTONE METHYLATION PROFILES ASSOCIATED WITH COGNITIVE CHANGES IN RESPONSE TO DEVELOPMENTAL ARSENIC EXPOSURE IN MICE. INORGANIC ARSENIC IS A XENOBIOTIC ENTERING THE BODY PRIMARILY THROUGH CONTAMINATED DRINKING WATER AND FOOD. THERE ARE DEFINED MECHANISMS THAT DESCRIBE ARSENIC'S ASSOCIATION WITH INCREASED CANCER INCIDENCE, HOWEVER MECHANISMS EXPLAINING ARSENIC EXPOSURE AND NEURODEVELOPMENTAL OR AGING DISORDERS ARE POORLY DEFINED. IN RECENT YEARS, ARSENIC EFFECTS ON EPIGENOME HAVE BECOME A PARTICULAR FOCUS. WE HYPOTHESIZE THAT HUMAN RELEVANT ARSENIC EXPOSURE DURING PARTICULAR DEVELOPMENTAL WINDOWS, OR LONG-TERM EXPOSURE LATER IN LIFE INDUCE PATHOPHYSIOLOGICAL NEURAL CHANGES THROUGH EPIGENOMIC ALTERATIONS, IN PARTICULAR HISTONE METHYLATION PROFILE, MANIFESTING AS COGNITIVE DECLINE. C57BL/6 WILD-TYPE MICE WERE CONTINUALLY EXPOSED TO SODIUM ARSENITE (100 MICROG/L) IN DRINKING WATER PRIOR TO MATING THROUGH WEANING OF THE EXPERIMENTAL PROGENY. A SECOND COHORT OF AGED APP/PS MICE WERE CHRONICALLY EXPOSED TO THE SAME LEVEL OF ARSENIC. COGNITIVE TESTING, HISTOLOGICAL EXAMINATION OF BRAINS AND GENOME-WIDE METHYLATION LEVELS OF H3K4ME3 AND H3K27ME3 EXAMINED AFTER CHIP-SEQ WERE USED TO DETERMINE THE EFFECTS OF ARSENIC EXPOSURE. DEVELOPMENTAL ARSENIC EXPOSURE CAUSED SIGNIFICANTLY DIMINISHED COGNITION IN WILD-TYPE MICE. THE ANALYSIS OF CHIP-SEQ DATA AND EXPERIMENTS WITH MOUSE EMBRYONIC STEM CELLS DEMONSTRATED THAT EPIGENETIC CHANGES INDUCED BY ARSENIC EXPOSURE TRANSLATED INTO GENE EXPRESSION ALTERATIONS ASSOCIATED WITH NEURONAL DEVELOPMENT AND NEUROLOGICAL DISEASE. INCREASED HIPPOCAMPAL AMYLOID PLAQUES LEVELS OF APP/PS MICE AND COGNITIVE DECLINE PROVIDED EVIDENCE THAT ARSENIC EXPOSURE AGGRAVATED AN EXISTING ALZHEIMER'S DISEASE-LIKE PHENOTYPE. WE SHOW DEVELOPMENTAL ARSENIC EXPOSURE SIGNIFICANTLY IMPACTS HISTONE MODIFICATIONS IN BRAIN WHICH REMAIN PRESENT INTO ADULTHOOD AND PROVIDE A POTENTIAL MECHANISM BY WHICH DEVELOPMENTAL ARSENIC EXPOSURE INFLUENCES COGNITIVE FUNCTIONS. WE ALSO SHOW THAT HUMAN RELEVANT, CHRONIC ARSENIC EXPOSURE HAS DELETERIOUS EFFECTS ON ADULT APP/PS MICE AND EXACERBATES EXISTING ALZHEIMER'S DISEASE-LIKE SYMPTOMS. THE RESULTS DEMONSTRATE HOW DEVELOPMENTAL ARSENIC EXPOSURE IMPACTS THE BRAIN EPIGENOME, LEADING TO ALTERED GENE EXPRESSION LATER IN LIFE. 2022 8 476 49 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 9 1655 29 DOSE-DEPENDENCE, SEX- AND TISSUE-SPECIFICITY, AND PERSISTENCE OF RADIATION-INDUCED GENOMIC DNA METHYLATION CHANGES. RADIATION IS A WELL-KNOWN GENOTOXIC AGENT AND HUMAN CARCINOGEN THAT GIVES RISE TO A VARIETY OF LONG-TERM EFFECTS. ITS DETRIMENTAL INFLUENCE ON CELLULAR FUNCTION IS ACTIVELY STUDIED NOWADAYS. ONE OF THE MOST ANALYZED, YET LEAST UNDERSTOOD LONG-TERM EFFECTS OF IONIZING RADIATION IS TRANSGENERATIONAL GENOMIC INSTABILITY. THE INHERITANCE OF GENOMIC INSTABILITY SUGGESTS THE POSSIBLE INVOLVEMENT OF EPIGENETIC MECHANISMS, SUCH AS CHANGES OF THE METHYLATION OF CYTOSINE RESIDUES LOCATED WITHIN CPG DINUCLEOTIDES. IN THE CURRENT STUDY WE EVALUATED THE DOSE-DEPENDENCE OF THE RADIATION-INDUCED GLOBAL GENOME DNA METHYLATION CHANGES. WE ALSO ANALYZED THE EFFECTS OF ACUTE AND CHRONIC HIGH DOSE (5GY) EXPOSURE ON DNA METHYLATION IN LIVER, SPLEEN, AND LUNG TISSUES OF MALE AND FEMALE MICE AND EVALUATED THE POSSIBLE PERSISTENCE OF THE RADIATION-INDUCED DNA METHYLATION CHANGES. HERE WE REPORT THAT RADIATION-INDUCED DNA METHYLATION CHANGES WERE SEX- AND TISSUE-SPECIFIC, DOSE-DEPENDENT, AND PERSISTENT. IN PARALLEL WE HAVE STUDIED THE LEVELS OF DNA DAMAGE IN THE EXPOSED TISSUES. BASED ON THE CORRELATION BETWEEN THE LEVELS OF DNA METHYLATION AND DNA DAMAGE WE PROPOSE THAT RADIATION-INDUCED GLOBAL GENOME DNA HYPOMETHYLATION IS DNA REPAIR-RELATED. 2004 10 990 40 CHRONIC SOCIAL STRESS INDUCES DNA METHYLATION CHANGES AT AN EVOLUTIONARY CONSERVED INTERGENIC REGION IN CHROMOSOME X. CHRONIC STRESS RESULTING FROM PROLONGED EXPOSURE TO NEGATIVE LIFE EVENTS INCREASES THE RISK OF MOOD AND ANXIETY DISORDERS. ALTHOUGH CHRONIC STRESS CAN CHANGE GENE EXPRESSION RELEVANT FOR BEHAVIOR, MOLECULAR REGULATORS OF THIS CHANGE HAVE NOT BEEN FULLY DETERMINED. ONE PROCESS THAT COULD PLAY A ROLE IS DNA METHYLATION, AN EPIGENETIC PROCESS WHEREBY A METHYL GROUP IS ADDED ONTO NUCLEOTIDES, PREDOMINANTLY CYTOSINE IN THE CPG CONTEXT, AND WHICH CAN BE INDUCED BY CHRONIC STRESS. IT IS UNKNOWN TO WHAT EXTENT CHRONIC SOCIAL DEFEAT, A MODEL OF HUMAN SOCIAL STRESS, INFLUENCES DNA METHYLATION PATTERNS ACROSS THE GENOME. OUR STUDY ADDRESSED THIS QUESTION BY USING A TARGETED-CAPTURE APPROACH CALLED METHYL-SEQ TO INVESTIGATE DNA METHYLATION PATTERNS OF THE DENTATE GYRUS AT PUTATIVE REGULATORY REGIONS ACROSS THE MOUSE GENOME FROM MICE EXPOSED TO 14 DAYS OF SOCIAL DEFEAT. FINDINGS WERE REPLICATED IN INDEPENDENT COHORTS BY BISULFITE-PYROSEQUENCING. TWO DIFFERENTIALLY METHYLATED REGIONS (DMRS) WERE IDENTIFIED. ONE DMR WAS LOCATED AT INTRON 9 OF DROSHA, AND IT SHOWED REDUCED METHYLATION IN STRESSED MICE. THIS OBSERVATION REPLICATED IN ONE OF TWO INDEPENDENT COHORTS. A SECOND DMR WAS IDENTIFIED AT AN INTERGENIC REGION OF CHROMOSOME X, AND METHYLATION IN THIS REGION WAS INCREASED IN STRESSED MICE. THIS METHYLATION DIFFERENCE REPLICATED IN TWO INDEPENDENT COHORTS AND IN MAJOR DEPRESSIVE DISORDER (MDD) POSTMORTEM BRAINS. THESE RESULTS HIGHLIGHT A REGION NOT PREVIOUSLY KNOWN TO BE DIFFERENTIALLY METHYLATED BY CHRONIC SOCIAL DEFEAT STRESS AND WHICH MAY BE INVOLVED IN MDD. 2018 11 5067 38 PHYSICAL ACTIVITY AND DNA METHYLATION IN HUMANS. PHYSICAL ACTIVITY IS A STRONG STIMULUS INFLUENCING THE OVERALL PHYSIOLOGY OF THE HUMAN BODY. EXERCISES LEAD TO BIOCHEMICAL CHANGES IN VARIOUS TISSUES AND EXERT AN IMPACT ON GENE EXPRESSION. EXERCISE-INDUCED CHANGES IN GENE EXPRESSION MAY BE MEDIATED BY EPIGENETIC MODIFICATIONS, WHICH REARRANGE THE CHROMATIN STRUCTURE AND THEREFORE MODULATE ITS ACCESSIBILITY FOR TRANSCRIPTION FACTORS. ONE OF SUCH EPIGENETIC MARK IS DNA METHYLATION THAT INVOLVES AN ATTACHMENT OF A METHYL GROUP TO THE FIFTH CARBON OF CYTOSINE RESIDUE PRESENT IN CG DINUCLEOTIDES (CPG). DNA METHYLATION IS CATALYZED BY A FAMILY OF DNA METHYLTRANSFERASES. THIS REVERSIBLE DNA MODIFICATION RESULTS IN THE RECRUITMENT OF PROTEINS CONTAINING METHYL BINDING DOMAIN AND FURTHER TRANSCRIPTIONAL CO-REPRESSORS LEADING TO THE SILENCING OF GENE EXPRESSION. THE ACCUMULATION OF CPG DINUCLEOTIDES, REFERRED AS CPG ISLANDS, OCCURS AT THE PROMOTER REGIONS IN A GREAT MAJORITY OF HUMAN GENES. THEREFORE, CHANGES IN DNA METHYLATION PROFILE AFFECT THE TRANSCRIPTION OF MULTIPLE GENES. A GROWING BODY OF EVIDENCE INDICATES THAT EXERCISE TRAINING MODULATES DNA METHYLATION IN MUSCLES AND ADIPOSE TISSUE. SOME OF THESE EPIGENETIC MARKERS WERE ASSOCIATED WITH A REDUCED RISK OF CHRONIC DISEASES. THIS REVIEW SUMMARIZES THE CURRENT KNOWLEDGE ABOUT THE INFLUENCE OF PHYSICAL ACTIVITY ON THE DNA METHYLATION STATUS IN HUMANS. 2021 12 1817 38 EFFECTS OF CHRONIC METAL EXPOSURE ON WILD FISH POPULATIONS REVEALED BY HIGH-THROUGHPUT CDNA SEQUENCING. GIVEN THE INHERENT VARIABILITY OF AQUATIC SYSTEMS, PREDICTING THE IN SITU EFFECTS OF CONTAMINANTS ON SUCH ECOSYSTEMS STILL REPRESENTS A MAJOR CHALLENGE FOR ECOTOXICOLOGY. IN THIS CONTEXT, TRANSCRIPTOMIC TOOLS CAN HELP IDENTIFY AND INVESTIGATE THE MECHANISMS OF TOXICITY BEYOND THE TRADITIONAL MORPHOMETRIC, PHYSIOLOGICAL AND POPULATION-LEVEL ENDPOINTS. IN THIS STUDY, WE USED THE 454 SEQUENCING TECHNOLOGY TO EXAMINE THE IN SITU EFFECTS OF CHRONIC METAL (CD, CU) EXPOSURE ON THE YELLOW PERCH (PERCA FLAVESCENS) TRANSCRIPTOME. TOTAL HEPATIC MRNA FROM FISH SAMPLED ALONG A POLYMETALLIC GRADIENT WAS EXTRACTED, REVERSE TRANSCRIBED, LABELED WITH UNIQUE BARCODE SEQUENCES AND SEQUENCED. THIS APPROACH ALLOWED US TO IDENTIFY CORRELATIONS BETWEEN THE TRANSCRIPTION LEVEL OF SINGLE GENES AND THE HEPATIC CONCENTRATIONS OF INDIVIDUAL METALS; 71% OF THE CORRELATIONS ESTABLISHED WERE NEGATIVE. CHRONIC METAL EXPOSURE WAS THUS ASSOCIATED WITH A DECREASE IN THE TRANSCRIPTION LEVELS OF NUMEROUS GENES INVOLVED IN PROTEIN BIOSYNTHESIS, IN THE IMMUNE SYSTEM, AND IN LIPID AND ENERGY METABOLISM. OUR RESULTS SUGGEST THAT THIS MARKED DECREASE COULD RESULT FROM AN IMPAIRMENT OF BILE ACID METABOLISM BY CD AND ENERGY RESTRICTION BUT ALSO FROM THE RECRUITMENT OF SEVERAL GENES INVOLVED IN EPIGENETIC MODIFICATIONS OF HISTONES AND DNA THAT LEAD TO GENE SILENCING. 2011 13 3969 37 LONG-LASTING DEPRESSION-LIKE BEHAVIOR AND EPIGENETIC CHANGES OF BDNF GENE EXPRESSION INDUCED BY PERINATAL EXPOSURE TO METHYLMERCURY. SUBSTANTIAL EVIDENCE INDICATES THAT PREDISPOSITION TO DISEASES CAN BE ACQUIRED DURING EARLY STAGES OF DEVELOPMENT AND INTERACTIONS BETWEEN ENVIRONMENTAL AND GENETIC FACTORS MAY BE IMPLICATED IN THE ONSET OF MANY PATHOLOGICAL CONDITIONS. DATA COLLECTED OVER SEVERAL DECADES HAVE SHOWN THAT CHEMICALS ARE AMONG THE RELEVANT FACTORS THAT CAN ENDANGER CNS. WE PREVIOUSLY SHOWED THAT PERINATAL EXPOSURE TO METHYLMERCURY (MEHG) CAUSES PERSISTENT CHANGES IN LEARNING AND MOTIVATIONAL BEHAVIOR IN MICE. IN THIS STUDY, WE REPORT THAT THE DEPRESSION-LIKE BEHAVIOR IN MEHG-EXPOSED MALE MICE IS REVERSED BY CHRONIC TREATMENT WITH THE ANTIDEPRESSANT FLUOXETINE. BEHAVIORAL ALTERATIONS ARE ASSOCIATED WITH A DECREASE IN BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) MRNA IN THE HIPPOCAMPAL DENTATE GYRUS AND FLUOXETINE TREATMENT RESTORES BDNF MRNA EXPRESSION. WE ALSO SHOW THAT MEHG-EXPOSURE INDUCES LONG-LASTING REPRESSIVE STATE OF THE CHROMATIN STRUCTURE AT THE BDNF PROMOTER REGION, IN PARTICULAR DNA HYPERMETHYLATION, AN INCREASE IN HISTONE H3-K27 TRI-METHYLATION AND A DECREASE IN H3 ACETYLATION AT THE PROMOTER IV. WHILE FLUOXETINE TREATMENT DOES NOT ALTER HYPERMETHYLATION OF H3-K27, IT SIGNIFICANTLY UP-REGULATES H3 ACETYLATION AT THE BDNF PROMOTER IV IN MEHG-EXPOSED MICE. OUR STUDY SHOWS THAT DEVELOPMENTAL EXPOSURE TO LOW LEVELS OF MEHG PREDISPOSES MICE TO DEPRESSION AND INDUCES EPIGENETIC SUPPRESSION OF BDNF GENE EXPRESSION IN THE HIPPOCAMPUS. 2008 14 4093 33 MATERNAL SEPARATION FOLLOWED BY CHRONIC MILD STRESS IN ADULTHOOD IS ASSOCIATED WITH CONCERTED EPIGENETIC REGULATION OF AP-1 COMPLEX GENES. DEPRESSION IS ONE OF THE MOST PREVALENT MENTAL DISEASES WORLDWIDE. PATIENTS WITH PSYCHIATRIC DISEASES OFTEN HAVE A HISTORY OF CHILDHOOD NEGLECT, INDICATING THAT EARLY-LIFE EXPERIENCES PREDISPOSE TO PSYCHIATRIC DISEASES IN ADULTHOOD. TWO STRONG MODELS WERE USED IN THE PRESENT STUDY: THE MATERNAL SEPARATION/EARLY DEPRIVATION MODEL (MS) AND THE CHRONIC MILD STRESS MODEL (CMS). IN BOTH MODELS, WE FOUND CHANGES IN THE EXPRESSION OF A NUMBER OF GENES SUCH AS CREB AND NPY. STRIKINGLY, THERE WAS A CLEAR REGULATION OF EXPRESSION OF FOUR GENES INVOLVED IN THE AP-1 COMPLEX: C-FOS, C-JUN, FOSB, AND JUN-B. INTERESTINGLY, DIFFERENT EXPRESSION LEVELS WERE OBSERVED DEPENDING ON THE MODEL, WHEREAS THE COMBINATION OF THE MODELS RESULTED IN A NORMAL LEVEL OF GENE EXPRESSION. THE EFFECTS OF MS AND CMS ON GENE EXPRESSION WERE ASSOCIATED WITH DISTINCT HISTONE METHYLATION/ACETYLATION PATTERNS OF ALL FOUR GENES. THE EPIGENETIC CHANGES, LIKE GENE EXPRESSION, WERE ALSO DEPENDENT ON THE SPECIFIC STRESSOR OR THEIR COMBINATION. THE OBTAINED RESULTS SUGGEST THAT SINGLE LIFE EVENTS LEAVE A MARK ON GENE EXPRESSION AND THE EPIGENETIC SIGNATURE OF GENE PROMOTERS, BUT A COMBINATION OF DIFFERENT STRESSORS AT DIFFERENT LIFE STAGES CAN FURTHER CHANGE GENE EXPRESSION THROUGH EPIGENETIC FACTORS, POSSIBLY CAUSING THE LONG-LASTING ADVERSE EFFECTS OF STRESS. 2021 15 3072 39 GENOME-WIDE DNA METHYLATION REPROGRAMMING IN RESPONSE TO INORGANIC ARSENIC LINKS INHIBITION OF CTCF BINDING, DNMT EXPRESSION AND CELLULAR TRANSFORMATION. CHRONIC LOW DOSE INORGANIC ARSENIC (IAS) EXPOSURE LEADS TO CHANGES IN GENE EXPRESSION AND EPITHELIAL-TO-MESENCHYMAL TRANSFORMATION. DURING THIS TRANSFORMATION, CELLS ADOPT A FIBROBLAST-LIKE PHENOTYPE ACCOMPANIED BY PROFOUND GENE EXPRESSION CHANGES. WHILE MANY MECHANISMS HAVE BEEN IMPLICATED IN THIS TRANSFORMATION, STUDIES THAT FOCUS ON THE ROLE OF EPIGENETIC ALTERATIONS IN THIS PROCESS ARE JUST EMERGING. DNA METHYLATION CONTROLS GENE EXPRESSION IN PHYSIOLOGIC AND PATHOLOGIC STATES. SEVERAL STUDIES SHOW ALTERATIONS IN DNA METHYLATION PATTERNS IN IAS-MEDIATED PATHOGENESIS, BUT THESE STUDIES FOCUSED ON SINGLE GENES. WE PRESENT A COMPREHENSIVE GENOME-WIDE DNA METHYLATION ANALYSIS USING METHYL-SEQUENCING TO MEASURE CHANGES BETWEEN NORMAL AND IAS-TRANSFORMED CELLS. ADDITIONALLY, THESE DIFFERENTIAL METHYLATION CHANGES CORRELATED POSITIVELY WITH CHANGES IN GENE EXPRESSION AND ALTERNATIVE SPLICING. INTERESTINGLY, MOST OF THESE DIFFERENTIALLY METHYLATED GENES FUNCTION IN CELL ADHESION AND COMMUNICATION PATHWAYS. TO GAIN INSIGHT INTO HOW GENOMIC DNA METHYLATION PATTERNS ARE REGULATED DURING IAS-MEDIATED CARCINOGENESIS, WE SHOW THAT IAS PROBABLY TARGETS CTCF BINDING AT THE PROMOTER OF DNA METHYLTRANSFERASES, REGULATING THEIR EXPRESSION. THESE FINDINGS REVEAL HOW CTCF BINDING REGULATES DNA METHYLTRANSFERASE TO REPROGRAM THE METHYLOME IN RESPONSE TO AN ENVIRONMENTAL TOXIN. 2017 16 2119 34 EPIGENETIC HISTONE MODIFICATION REGULATES DEVELOPMENTAL LEAD EXPOSURE INDUCED HYPERACTIVITY IN RATS. LEAD (PB) EXPOSURE WAS COMMONLY CONSIDERED AS A HIGH ENVIRONMENTAL RISK FACTOR FOR THE DEVELOPMENT OF ATTENTION-DEFICIT/HYPERACTIVITY DISORDER (ADHD). HOWEVER, THE MOLECULAR BASIS OF THIS PATHOLOGICAL PROCESS STILL REMAINS ELUSIVE. IN LIGHT OF THE ROLE OF EPIGENETICS IN MODULATING THE NEUROLOGICAL DISEASE AND THE CAUSATIVE ENVIRONMENT, THE ALTERATIONS OF HISTONE MODIFICATIONS IN THE HIPPOCAMPUS OF RATS EXPOSED BY VARIOUS DOSES OF LEAD, ALONG WITH CONCOMITANT BEHAVIORAL DEFICITS, WERE INVESTIGATED IN THIS STUDY. ACCORDING TO THE FREE AND FORCED OPEN FIELD TEST, THERE SHOWED THAT IN A DOSAGE-DEPENDENT MANNER, LEAD EXPOSURE COULD RESULT IN THE INCREASED LOCOMOTOR ACTIVITY OF RATS, THAT IS, HYPERACTIVITY: A SUBTYPE OF ADHD. WESTERN BLOTTING ASSAYS REVEALED THAT THE LEVELS OF HISTONE ACETYLATION INCREASED SIGNIFICANTLY IN THE HIPPOCAMPUS BY CHRONIC LEAD EXPOSURE, WHILE NO DRAMATIC CHANGES WERE DETECTED IN TERMS OF EXPRESSION YIELDS OF ADHD-RELATED DOPAMINERGIC PROTEINS, INDICATING THAT HISTONE ACETYLATION PLAYS ESSENTIAL ROLES IN THIS TOXICANT-INVOLVED PATHOGENESIS. IN ADDITION, THE INCREASED LEVEL OF HISTONE ACETYLATION MIGHT BE ATTRIBUTED TO THE ENZYMATIC ACTIVITY OF P300, A TYPICAL HISTONE ACETYLTRANSFERASE, AS THE TRANSCRIPTIONAL LEVEL OF P300 WAS SIGNIFICANTLY INCREASED UPON HIGHER-DOSE PB EXPOSURE. IN SUMMARY, THIS STUDY FIRST DISCOVERED THE EPIGENETIC MECHANISM BRIDGING THE ENVIRONMENTAL INFLUENCE (PB) AND THE DISEASE ITSELF (ADHD) IN THE HISTONE MODIFICATION LEVEL, PAVING THE WAY FOR THE COMPREHENSIVE UNDERSTANDING OF ADHD'S ETIOLOGY AND IN FURTHER STEPS, ESTABLISHING THE THERAPY STRATEGY OF THIS WIDESPREAD NEUROLOGICAL DISORDER. 2014 17 1815 26 EFFECTS OF CHRONIC EXPOSURE TO ARSENIC AND ESTROGEN ON EPIGENETIC REGULATORY GENES EXPRESSION AND EPIGENETIC CODE IN HUMAN PROSTATE EPITHELIAL CELLS. CHRONIC EXPOSURES TO ARSENIC AND ESTROGEN ARE KNOWN RISK FACTORS FOR PROSTATE CANCER. THOUGH THE EVIDENCE SUGGESTS THAT EXPOSURE TO ARSENIC OR ESTROGENS CAN DISRUPT NORMAL DNA METHYLATION PATTERNS AND HISTONE MODIFICATIONS, THE MECHANISMS BY WHICH THESE CHEMICALS INDUCE EPIGENETIC CHANGES ARE NOT FULLY UNDERSTOOD. MOREOVER, THE EPIGENETIC EFFECTS OF CO-EXPOSURE TO THESE TWO CHEMICALS ARE NOT KNOWN. THEREFORE, THE OBJECTIVE OF THIS STUDY WAS TO EVALUATE THE EFFECTS OF CHRONIC EXPOSURE TO ARSENIC AND ESTROGEN, BOTH ALONE AND IN COMBINATION, ON THE EXPRESSION OF EPIGENETIC REGULATORY GENES, THEIR CONSEQUENCES ON DNA METHYLATION, AND HISTONE MODIFICATIONS. HUMAN PROSTATE EPITHELIAL CELLS, RWPE-1, CHRONICALLY EXPOSED TO ARSENIC AND ESTROGEN ALONE AND IN COMBINATION WERE USED FOR ANALYSIS OF EPIGENETIC REGULATORY GENES EXPRESSION, GLOBAL DNA METHYLATION CHANGES, AND HISTONE MODIFICATIONS AT PROTEIN LEVEL. THE RESULT OF THIS STUDY REVEALED THAT EXPOSURE TO ARSENIC, ESTROGEN, AND THEIR COMBINATION ALTERS THE EXPRESSION OF EPIGENETIC REGULATORY GENES AND CHANGES GLOBAL DNA METHYLATION AND HISTONE MODIFICATION PATTERNS IN RWPE-1 CELLS. THESE CHANGES WERE SIGNIFICANTLY GREATER IN ARSENIC AND ESTROGEN COMBINATION TREATED GROUP THAN INDIVIDUALLY TREATED GROUP. THE FINDINGS OF THIS STUDY WILL HELP EXPLAIN THE EPIGENETIC MECHANISM OF ARSENIC- AND/OR ESTROGEN-INDUCED PROSTATE CARCINOGENESIS. 2012 18 978 39 CHRONIC OXIDATIVE STRESS CAUSES ESTROGEN-INDEPENDENT AGGRESSIVE PHENOTYPE, AND EPIGENETIC INACTIVATION OF ESTROGEN RECEPTOR ALPHA IN MCF-7 BREAST CANCER CELLS. THE ROLE OF CHRONIC OXIDATIVE STRESS IN THE DEVELOPMENT AND AGGRESSIVE GROWTH OF ESTROGEN RECEPTOR (ER)-POSITIVE BREAST CANCER IS WELL KNOWN; HOWEVER, THE MECHANISTIC UNDERSTANDING IS NOT CLEAR. ESTROGEN-INDEPENDENT GROWTH IS ONE OF THE FEATURES OF AGGRESSIVE SUBTYPE OF BREAST CANCER. THEREFORE, THE OBJECTIVE OF THIS STUDY WAS TO EVALUATE THE EFFECT OF OXIDATIVE STRESS ON ESTROGEN SENSITIVITY AND EXPRESSION OF NUCLEAR ESTROGEN RECEPTORS IN ER-POSITIVE BREAST CANCER CELLS. MCF-7 CELLS CHRONICALLY EXPOSED TO HYDROGEN PEROXIDE WERE USED AS A CELL MODEL IN THIS STUDY, AND THEIR GROWTH IN RESPONSE TO 17-BETA ESTRADIOL WAS EVALUATED BY CELL VIABILITY, CELL CYCLE, AND CELL MIGRATION ANALYSIS. RESULTS WERE FURTHER CONFIRMED AT MOLECULAR LEVEL BY ANALYSIS OF GENE EXPRESSIONS AT TRANSCRIPT AND PROTEIN LEVELS. HISTONE H3 MODIFICATIONS, EXPRESSION OF EPIGENETIC REGULATORY GENES, AND THE EFFECT OF DNA DEMETHYLATION WERE ALSO ANALYZED. LOSS OF GROWTH IN RESPONSE TO ESTROGEN WITH A DECREASE IN ERALPHA EXPRESSION WAS OBSERVED IN MCF-7 CELLS ADAPTED TO CHRONIC OXIDATIVE STRESS. INCREASES IN MTTFA AND NRF1 IN THESE CELLS FURTHER SUGGESTED THE ROLE OF MITOCHONDRIA-DEPENDENT REDOX-SENSITIVE GROWTH SIGNALING AS AN ALTERNATIVE PATHWAY TO ESTROGEN-DEPENDENT GROWTH. CHANGES IN EXPRESSION OF EPIGENETIC REGULATORY GENES, LEVELS OF HISTONE H3 MODIFICATIONS AS WELL AS SIGNIFICANT RESTORATIONS OF BOTH ERALPHA EXPRESSION AND ESTROGEN RESPONSE BY 5-AZA-2'-DEOXYCYTIDINE FURTHER CONFIRMED THE EPIGENETIC BASIS FOR ESTROGEN-INDEPENDENT GROWTH IN THESE CELLS. IN CONCLUSION, RESULTS OF THIS STUDY SUGGEST THAT CHRONIC OXIDATIVE STRESS CAN CONVERT ESTROGEN-DEPENDENT NONAGGRESSIVE BREAST CANCER CELLS INTO ESTROGEN-INDEPENDENT AGGRESSIVE FORM POTENTIALLY BY EPIGENETIC MECHANISM. 2015 19 3738 35 INORGANIC ARSENIC-INDUCED CELLULAR TRANSFORMATION IS COUPLED WITH GENOME WIDE CHANGES IN CHROMATIN STRUCTURE, TRANSCRIPTOME AND SPLICING PATTERNS. BACKGROUND: ARSENIC (AS) EXPOSURE IS A SIGNIFICANT WORLDWIDE ENVIRONMENTAL HEALTH CONCERN. LOW DOSE, CHRONIC ARSENIC EXPOSURE HAS BEEN ASSOCIATED WITH A HIGHER THAN NORMAL RISK OF SKIN, LUNG, AND BLADDER CANCER, AS WELL AS CARDIOVASCULAR DISEASE AND DIABETES. WHILE ARSENIC-INDUCED BIOLOGICAL CHANGES PLAY A ROLE IN DISEASE PATHOLOGY, LITTLE IS KNOWN ABOUT THE DYNAMIC CELLULAR CHANGES RESULTING FROM ARSENIC EXPOSURE AND WITHDRAWAL. RESULTS: IN THESE STUDIES, WE SOUGHT TO UNDERSTAND THE MOLECULAR MECHANISMS BEHIND THE BIOLOGICAL CHANGES INDUCED BY ARSENIC EXPOSURE. A COMPREHENSIVE GLOBAL APPROACH WAS EMPLOYED TO DETERMINE GENOME-WIDE CHANGES TO CHROMATIN STRUCTURE, TRANSCRIPTOME PATTERNS AND SPLICING PATTERNS IN RESPONSE TO CHRONIC LOW DOSE ARSENIC AND ITS SUBSEQUENT WITHDRAWAL. OUR RESULTS SHOW THAT CELLS EXPOSED TO CHRONIC LOW DOSES OF SODIUM ARSENITE HAVE DISTINCT TEMPORAL AND COORDINATED CHROMATIN, GENE EXPRESSION, AND MIRNA CHANGES CONSISTENT WITH DIFFERENTIATION AND ACTIVATION OF MULTIPLE BIOCHEMICAL PATHWAYS. MOST OF THESE TEMPORAL PATTERNS IN GENE EXPRESSION ARE REVERSED WHEN ARSENIC IS WITHDRAWN. HOWEVER, SOME GENE EXPRESSION PATTERNS REMAINED ALTERED, PLAUSIBLY AS A RESULT OF AN ADAPTIVE RESPONSE BY CELLS. ADDITIONALLY, THE CORRELATION OF CHANGES TO GENE EXPRESSION AND CHROMATIN STRUCTURE SOLIDIFY THE ROLE OF CHROMATIN STRUCTURE IN GENE REGULATORY CHANGES DUE TO ARSENITE EXPOSURE. LASTLY, WE SHOW THAT ARSENITE EXPOSURE INFLUENCES GENE REGULATION BOTH AT THE INITIATION OF TRANSCRIPTION AS WELL AS AT THE LEVEL OF SPLICING. CONCLUSIONS: OUR RESULTS SHOW THAT ADAPTATION OF CELLS TO IAS-MEDIATED EMT IS COUPLED TO CHANGES IN CHROMATIN STRUCTURE EFFECTING DIFFERENTIAL TRANSCRIPTIONAL AND SPLICING PATTERNS OF GENES. THESE STUDIES PROVIDE NEW INSIGHTS INTO THE MECHANISM OF IAS-MEDIATED PATHOLOGY, WHICH INCLUDES EPIGENETIC CHROMATIN CHANGES COUPLED WITH CHANGES TO THE TRANSCRIPTOME AND SPLICING PATTERNS OF KEY GENES. 2015 20 1269 36 CYTOSINE METHYLATION CHANGES IN ENHANCER REGIONS OF CORE PRO-FIBROTIC GENES CHARACTERIZE KIDNEY FIBROSIS DEVELOPMENT. BACKGROUND: ONE IN ELEVEN PEOPLE IS AFFECTED BY CHRONIC KIDNEY DISEASE, A CONDITION CHARACTERIZED BY KIDNEY FIBROSIS AND PROGRESSIVE LOSS OF KIDNEY FUNCTION. EPIDEMIOLOGICAL STUDIES INDICATE THAT ADVERSE INTRAUTERINE AND POSTNATAL ENVIRONMENTS HAVE A LONG-LASTING ROLE IN CHRONIC KIDNEY DISEASE DEVELOPMENT. EPIGENETIC INFORMATION REPRESENTS A PLAUSIBLE CARRIER FOR MEDIATING THIS PROGRAMMING EFFECT. HERE WE DEMONSTRATE THAT GENOME-WIDE CYTOSINE METHYLATION PATTERNS OF HEALTHY AND CHRONIC KIDNEY DISEASE TUBULE SAMPLES OBTAINED FROM PATIENTS SHOW SIGNIFICANT DIFFERENCES. RESULTS: WE IDENTIFY DIFFERENTIALLY METHYLATED REGIONS AND VALIDATE THESE IN A LARGE REPLICATION DATASET. THE DIFFERENTIALLY METHYLATED REGIONS ARE RARELY OBSERVED ON PROMOTERS, BUT MOSTLY OVERLAP WITH PUTATIVE ENHANCER REGIONS, AND THEY ARE ENRICHED IN CONSENSUS BINDING SEQUENCES FOR IMPORTANT RENAL TRANSCRIPTION FACTORS. THIS INDICATES THEIR IMPORTANCE IN GENE EXPRESSION REGULATION. A CORE SET OF GENES THAT ARE KNOWN TO BE RELATED TO KIDNEY FIBROSIS, INCLUDING GENES ENCODING COLLAGENS, SHOW CYTOSINE METHYLATION CHANGES CORRELATING WITH DOWNSTREAM TRANSCRIPT LEVELS. CONCLUSIONS: OUR REPORT RAISES THE POSSIBILITY THAT EPIGENETIC DYSREGULATION PLAYS A ROLE IN CHRONIC KIDNEY DISEASE DEVELOPMENT VIA INFLUENCING CORE PRO-FIBROTIC PATHWAYS AND CAN AID THE DEVELOPMENT OF NOVEL BIOMARKERS AND FUTURE THERAPEUTICS. 2013