1 579 163 BEHAVIORAL AND MOLECULAR NEUROEPIGENETIC ALTERATIONS IN PRENATALLY STRESSED MICE: RELEVANCE FOR THE STUDY OF CHROMATIN REMODELING PROPERTIES OF ANTIPSYCHOTIC DRUGS. WE HAVE RECENTLY REPORTED THAT MICE BORN FROM DAMS STRESSED DURING PREGNANCY (PRS MICE), IN ADULTHOOD, HAVE BEHAVIORAL DEFICITS REMINISCENT OF BEHAVIORS OBSERVED IN SCHIZOPHRENIA (SZ) AND BIPOLAR (BP) DISORDER PATIENTS. FURTHERMORE, WE HAVE SHOWN THAT THE FRONTAL CORTEX (FC) AND HIPPOCAMPUS OF ADULT PRS MICE, LIKE THAT OF POSTMORTEM CHRONIC SZ PATIENTS, ARE CHARACTERIZED BY INCREASES IN DNA-METHYLTRANSFERASE 1 (DNMT1), TEN-ELEVEN METHYLCYTOSINE DIOXYGENASE 1 (TET1) AND EXHIBIT AN ENRICHMENT OF 5-METHYLCYTOSINE (5MC) AND 5-HYDROXYMETHYLCYTOSINE (5HMC) AT NEOCORTICAL GABAERGIC AND GLUTAMATERGIC GENE PROMOTERS. HERE, WE SHOW THAT THE BEHAVIORAL DEFICITS AND THE INCREASED 5MC AND 5HMC AT GLUTAMIC ACID DECARBOXYLASE 67 (GAD1), REELIN (RELN) AND BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) PROMOTERS AND THE REDUCED EXPRESSION OF THE MESSENGER RNAS (MRNAS) AND PROTEINS CORRESPONDING TO THESE GENES IN FC OF ADULT PRS MICE IS REVERSED BY TREATMENT WITH CLOZAPINE (5 MG KG(-1) TWICE A DAY FOR 5 DAYS) BUT NOT BY HALOPERIDOL (1 MG KG(-1) TWICE A DAY FOR 5 DAYS). INTERESTINGLY, CLOZAPINE HAD NO EFFECT ON EITHER THE BEHAVIOR, PROMOTER METHYLATION OR THE EXPRESSION OF THESE MRNAS AND PROTEINS WHEN ADMINISTERED TO OFFSPRING OF NONSTRESSED PREGNANT MICE. CLOZAPINE, BUT NOT HALOPERIDOL, REDUCED THE ELEVATED LEVELS OF DNMT1 AND TET1, AS WELL AS THE ELEVATED LEVELS OF DNMT1 BINDING TO GAD1, RELN AND BDNF PROMOTERS IN PRS MICE SUGGESTING THAT CLOZAPINE, UNLIKE HALOPERIDOL, MAY LIMIT DNA METHYLATION BY INTERFERING WITH DNA METHYLATION DYNAMICS. WE CONCLUDE THAT THE PRS MOUSE MODEL MAY BE USEFUL PRECLINICALLY IN SCREENING FOR THE POTENTIAL EFFICACY OF ANTIPSYCHOTIC DRUGS ACTING ON ALTERED EPIGENETIC MECHANISMS. FURTHERMORE, PRS MICE MAY BE INVALUABLE FOR UNDERSTANDING THE ETIOPATHOGENESIS OF SZ AND BP DISORDER AND FOR PREDICTING TREATMENT RESPONSES AT EARLY STAGES OF THE ILLNESS ALLOWING FOR EARLY DETECTION AND REMEDIAL INTERVENTION. 2016 2 4390 62 MODELING THE MOLECULAR EPIGENETIC PROFILE OF PSYCHOSIS IN PRENATALLY STRESSED MICE. BASED ON POSTMORTEM BRAIN STUDIES, OUR OVERARCHING EPIGENETIC HYPOTHESIS IS THAT CHRONIC SCHIZOPHRENIA (SZ) IS A PSYCHOPATHOLOGICAL CONDITION INVOLVING DYSREGULATION OF THE DYNAMIC EQUILIBRIUM AMONG DNA METHYLATION/DEMETHYLATION NETWORK COMPONENTS AND THE EXPRESSION OF SZ TARGET GENES, INCLUDING GABAERGIC AND GLUTAMATERGIC GENES. SZ HAS A NATURAL COURSE, STARTING WITH A PRODROMAL PHASE, A FIRST EPISODE THAT OCCURS IN ADOLESCENTS OR IN YOUNG ADULTS, AND LATER DETERIORATION OVER THE ADULT YEARS. HENCE, THE EPIGENETIC STATUS AT EACH NEURODEVELOPMENTAL STAGE OF THE DISEASE CANNOT BE STUDIED JUST IN POSTMORTEM BRAIN OF CHRONIC SZ PATIENTS, BUT REQUIRES THE USE OF NEURODEVELOPMENTAL ANIMAL MODELS. WE HAVE DIRECTED THE FOCUS OF OUR RESEARCH TOWARD STUDYING THE EPIGENETIC SIGNATURE OF THE SZ BRAIN IN THE OFFSPRING OF DAMS STRESSED DURING PREGNANCY (PRS MICE). ADULT PRS MICE HAVE BEHAVIORAL DEFICITS REMINISCENT OF BEHAVIORS OBSERVED IN PSYCHOTIC PATIENTS. THE ADULT PRS BRAIN, LIKE THAT OF POSTMORTEM CHRONIC SZ PATIENTS, IS CHARACTERIZED BY A SIGNIFICANT INCREASE IN DNA METHYLTRANSFERASE 1, TET METHYLCYTOSINE DIOXYGENASE 1 (TET1), 5-METHYLCYTOSINE, AND 5-HYDROXYMETHYLCYTOSINE AT SZ CANDIDATE GENE PROMOTERS AND A REDUCTION IN THE EXPRESSION OF GLUTAMATERGIC AND GABAERGIC GENES. IN PRS MICE, MEASUREMENTS OF EPIGENETIC BIOMARKERS FOR SZ CAN BE ASSESSED AT DIFFERENT STAGES OF DEVELOPMENT WITH THE GOAL OF FURTHER ELUCIDATING THE PATHOPHYSIOLOGY OF THIS DISEASE AND PREDICTING TREATMENT RESPONSES AT SPECIFIC STAGES OF THE ILLNESS, WITH PARTICULAR ATTENTION TO EARLY DETECTION AND POSSIBLY EARLY INTERVENTION. 2014 3 5111 31 POLYSOME-CAGE OF TCL1-DRIVEN CHRONIC LYMPHOCYTIC LEUKEMIA REVEALED MULTIPLE N-TERMINALLY ALTERED EPIGENETIC REGULATORS AND A TRANSLATION STRESS SIGNATURE. THE TRANSFORMATION OF NORMAL TO MALIGNANT CELLS IS ACCOMPANIED BY SUBSTANTIAL CHANGES IN GENE EXPRESSION PROGRAMS THROUGH DIVERSE MECHANISMS. HERE, WE EXAMINED THE CHANGES IN THE LANDSCAPE OF TRANSCRIPTION START SITES AND ALTERNATIVE PROMOTER (AP) USAGE AND THEIR IMPACT ON THE TRANSLATOME IN TCL1-DRIVEN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). OUR FINDINGS REVEALED A MARKED ELEVATION OF APS IN CLL B CELLS FROM EMICRO-TCL1 TRANSGENIC MICE, WHICH ARE PARTICULARLY ENRICHED WITH INTRA-GENIC PROMOTERS THAT GENERATE N-TERMINALLY TRUNCATED OR MODIFIED PROTEINS. INTRA-GENIC PROMOTER ACTIVATION IS MEDIATED BY (1) LOSS OF FUNCTION OF 'CLOSED CHROMATIN' EPIGENETIC REGULATORS DUE TO THE GENERATION OF INACTIVE N-TERMINALLY MODIFIED ISOFORMS OR REDUCED EXPRESSION; (2) UPREGULATION OF TRANSCRIPTION FACTORS, INCLUDING C-MYC, TARGETING THE INTRA-GENIC PROMOTERS AND THEIR ASSOCIATED ENHANCERS. EXOGENOUS EXPRESSION OF TCL1 IN MEFS IS SUFFICIENT TO INDUCE INTRA-GENIC PROMOTERS OF EPIGENETIC REGULATORS AND PROMOTE C-MYC EXPRESSION. WE FURTHER FOUND A DRAMATIC TRANSLATION DOWNREGULATION OF TRANSCRIPTS BEARING CNY CAP-PROXIMAL TRINUCLEOTIDES, REMINISCENT OF CELLS UNDERGOING METABOLIC STRESS. THESE FINDINGS UNCOVERED THE ROLE OF TCL1 ONCOGENIC FUNCTION IN ALTERING PROMOTER USAGE AND MRNA TRANSLATION IN LEUKEMOGENESIS. 2022 4 5168 33 PRECONCEPTIONAL PATERNAL EXPOSURE TO A SINGLE TRAUMATIC EVENT AFFECTS POSTNATAL GROWTH OF FEMALE BUT NOT MALE OFFSPRING. ALTHOUGH PRECONCEPTIONAL AND PERICONCEPTIONAL MATERNAL STRESS IS A RECOGNIZED RISK FACTOR FOR OFFSPRING NEURODEVELOPMENTAL DISTURBANCES, LESS IS KNOWN ABOUT THE RELEVANCE OF PATERNAL EXPOSURES. THESE HAVE HITHERTO BEEN INVESTIGATED MAINLY WITH RESPECT TO SUBSTANCE-INDUCED IMPAIRMENT IN THE PROGENY. IN RECENT YEARS, EXPERIENTIAL INFLUENCES ON OFFSPRING HAVE COME INTO FOCUS THROUGH GROWING INSIGHT INTO EPIGENETIC MECHANISMS SUCH AS NONGENETIC MODES OF TRANSMISSION. THE EFFECT OF CHRONIC AND/OR EARLY MANIPULATIONS IN MALES HAS BEEN STUDIED BUT MUCH LESS IS KNOWN ABOUT THE POTENTIAL IMPACT OF SINGULAR MANIPULATIONS IN OLDER INDIVIDUALS. WE INVESTIGATED THE INFLUENCE OF A STRONG STRESSOR EXPOSURE, REMINISCENT OF A TRAUMATIC EVENT, IN ADULT MALE MICE ON OFFSPRING BEHAVIOR. MALE MICE, 6 WEEKS OF AGE, RECEIVED A STRONG FOOTSHOCK AND WERE MATED TO NAIVE FEMALES SEVERAL WEEKS LATER. MALE AND FEMALE OFFSPRING WERE INVESTIGATED IN A VARIETY OF TESTS FOR ANXIETY-LIKE AND DEPRESSION-LIKE BEHAVIORS. IN ADDITION, BODYWEIGHT DEVELOPMENT WAS ASSESSED. ALTHOUGH WE DID NOT OBSERVE ANY ALTERATIONS IN ANXIETY-LIKE AND DEPRESSIVE-LIKE BEHAVIORAL INDICES, WE RECORDED REDUCED BODYWEIGHT DEVELOPMENT IN THE FEMALE OFFSPRING. OUR DATA EMPHASIZE THE RELEVANCE OF SEX AS A (CO)DETERMINANT OF OUTCOMES IN THE WAKE OF PARENTAL MANIPULATIONS. THEY FURTHER SUGGEST THAT THE WINDOW OF VULNERABILITY FOR THE INDUCTION OF PATRILINEAR EFFECTS MIGHT BE WIDER THAN THAT CURRENTLY ASSUMED. 2013 5 1538 48 DNA METHYLATION IN ANIMAL MODELS OF PSYCHOSIS. SCHIZOPHRENIA (SZ) IS A DEBILITATING DISEASE THAT IMPACTS 1% OF THE POPULATION WORLDWIDE. ASSOCIATION STUDIES HAVE SHOWN THAT INHERITED GENETIC MUTATIONS ACCOUNT FOR A PORTION OF DISEASE RISK. HOWEVER, ENVIRONMENTAL FACTORS PLAY AN IMPORTANT ROLE IN THE PATHOPHYSIOLOGY OF THE DISEASE BY ALTERING CELLULAR EPIGENETIC MARKS AT THE LEVEL OF CHROMATIN. POSTMORTEM BRAIN STUDIES OF SZ SUBJECTS SUGGEST THAT THE DYNAMIC EQUILIBRIUM BETWEEN DNA METHYLATION AND DEMETHYLATION NETWORK COMPONENTS IS DISRUPTED AT THE LEVEL OF INDIVIDUAL SZ TARGET GENES. HEREIN, WE REVIEW THE ROLE OF DNA METHYLATION AND DEMETHYLATION IN THE CONTEXT OF WHAT IS CURRENTLY KNOWN REGARDING SZ. FURTHERMORE, WE DESCRIBE THE DEFICITS THAT ACCOMPANY TWO MOUSE MODELS OF SZ. THE CHRONIC METHIONINE MOUSE MODEL OF SZ IS PREDICATED ON THE ADMINISTRATION OF METHIONINE TO SZ PATIENTS AND CONTROLS IN THE CONTEXT OF CLINICAL STUDIES THAT WERE CARRIED OUT DURING THE 1960S AND 1970S. THE PRENATAL RESTRAINT STRESS MODEL OF SZ IS BASED ON A PROLONGED STRESS PARADIGM ADMINISTERED TO PREGNANT DAMS DURING GESTATION DAYS 7-21. THE ADULT OFFSPRING OF THESE DAMS SHOW VARIOUS BEHAVIORAL AND BIOCHEMICAL DEFICITS IN ADULTHOOD. BOTH MODELS ARE EPIGENETIC IN ORIGIN AND MIMIC THE POSITIVE AND NEGATIVE SYMPTOMS, AS WELL AS THE COGNITIVE ENDOPHENOTYPES COMMONLY OBSERVED IN SZ PATIENTS. WE ALSO DISCUSS THE UTILITY OF TYPICAL AND ATYPICAL ANTIPSYCHOTIC DRUGS IN ALLEVIATING THESE SYMPTOMS IN EACH MODEL. 2018 6 2138 31 EPIGENETIC INHERITANCE OF FETAL GENES IN ALLERGIC ASTHMA. ASTHMA HAS BEEN ASSOCIATED WITH AN EXAGGERATED T-HELPER TYPE 2 (TH2) OVER TH1 RESPONSES TO ALLERGIC AND NONALLERGIC STIMULI, WHICH LEADS TO CHRONIC AIRWAY INFLAMMATION AND AIRWAY REMODELING. IN THE PRESENT ARTICLE, WE PROPOSE THAT MANY OF THE GENES INVOLVED IN IGE SYNTHESIS AND AIRWAYS (RE)MODELING IN ASTHMA ARE PERSISTENT OR REMINISCENT FETAL GENES WHICH MAY NOT BE SILENCED DURING EARLY INFANCY (OR LATE PREGNANCY). GENES OF THE EMBRYOLOGIC DIFFERENTIATION OF ECTODERMIC AND ENDODERMIC TISSUES MAY EXPLAIN SOME OF THE PATTERNS OF AIRWAY REMODELING IN ASTHMA. IN UTERO PROGRAMMING LEADS TO GENE EXPRESSION, THE PERSISTENCE OF WHICH MAY BE ASSOCIATED WITH EPIGENETIC INHERITANCE PHENOMENA INDUCED BY NONSPECIFIC ENVIRONMENTAL FACTORS. CLEAR DELINEATION OF THESE ISSUES MAY YIELD NEW INFORMATION ON THE MECHANISMS OF ASTHMA AND NEW TARGETS FOR THERAPEUTIC INTERVENTION AND PRIMARY PREVENTION. 2004 7 4935 33 PATERNAL COCAINE TAKING ELICITS EPIGENETIC REMODELING AND MEMORY DEFICITS IN MALE PROGENY. PATERNAL ENVIRONMENTAL PERTURBATIONS INCLUDING EXPOSURE TO DRUGS OF ABUSE CAN PRODUCE PROFOUND EFFECTS ON THE PHYSIOLOGY AND BEHAVIOR OF OFFSPRING VIA EPIGENETIC MODIFICATIONS. HERE WE SHOW THAT ADULT DRUG-NAIVE MALE OFFSPRING OF COCAINE-EXPOSED SIRES HAVE MEMORY FORMATION DEFICITS AND ASSOCIATED REDUCTIONS IN NMDA RECEPTOR-MEDIATED HIPPOCAMPAL SYNAPTIC PLASTICITY. REDUCED LEVELS OF THE ENDOGENOUS NMDA RECEPTOR CO-AGONIST D-SERINE WERE ACCOMPANIED BY INCREASED EXPRESSION OF THE D-SERINE DEGRADING ENZYME D-AMINO ACID OXIDASE (DAO1) IN THE HIPPOCAMPUS OF COCAINE-SIRED MALE PROGENY. INCREASED DAO1 TRANSCRIPTION WAS ASSOCIATED WITH ENRICHMENT OF PERMISSIVE EPIGENETIC MARKS ON HISTONE PROTEINS IN THE HIPPOCAMPUS OF MALE COCAINE-SIRED PROGENY, SOME OF WHICH WERE ENHANCED NEAR THE DAO1 LOCUS. FINALLY, HIPPOCAMPAL ADMINISTRATION OF D-SERINE REVERSED BOTH THE MEMORY FORMATION AND SYNAPTIC PLASTICITY DEFICITS. COLLECTIVELY, THESE RESULTS DEMONSTRATE THAT PATERNAL COCAINE EXPOSURE PRODUCES EPIGENETIC REMODELING IN THE HIPPOCAMPUS LEADING TO NMDA RECEPTOR-DEPENDENT MEMORY FORMATION AND SYNAPTIC PLASTICITY IMPAIRMENTS ONLY IN MALE PROGENY, WHICH HAS SIGNIFICANT IMPLICATIONS FOR THE MALE DESCENDANTS OF CHRONIC COCAINE USERS. 2017 8 252 31 ADVANCEMENTS IN THE UNDERLYING PATHOGENESIS OF SCHIZOPHRENIA: IMPLICATIONS OF DNA METHYLATION IN GLIAL CELLS. SCHIZOPHRENIA (SZ) IS A CHRONIC AND SEVERE MENTAL ILLNESS FOR WHICH CURRENTLY THERE IS NO CURE. AT PRESENT, THE EXACT MOLECULAR MECHANISM INVOLVED IN THE UNDERLYING PATHOGENESIS OF SZ IS UNKNOWN. THE DISEASE IS THOUGHT TO BE CAUSED BY A COMBINATION OF GENETIC, BIOLOGICAL, PSYCHOLOGICAL, AND ENVIRONMENTAL FACTORS. RECENT STUDIES HAVE SHOWN THAT EPIGENETIC REGULATION IS INVOLVED IN SZ PATHOLOGY. SPECIFICALLY, DNA METHYLATION, ONE OF THE EARLIEST FOUND EPIGENETIC MODIFICATIONS, HAS BEEN EXTENSIVELY LINKED TO MODULATION OF NEURONAL FUNCTION, LEADING TO PSYCHIATRIC DISORDERS SUCH AS SZ. HOWEVER, INCREASING EVIDENCE INDICATES THAT GLIAL CELLS, ESPECIALLY DYSFUNCTIONAL OLIGODENDROCYTES UNDERGO DNA METHYLATION CHANGES THAT CONTRIBUTE TO THE PATHOGENESIS OF SZ. THIS REVIEW PRIMARILY FOCUSES ON DNA METHYLATION INVOLVED IN GLIAL DYSFUNCTIONS IN SZ. CLARIFYING THIS MECHANISM MAY LEAD TO THE DEVELOPMENT OF NEW THERAPEUTIC INTERVENTIONAL STRATEGIES FOR THE TREATMENT OF SZ AND OTHER ILLNESSES BY CORRECTING ABNORMAL METHYLATION IN GLIAL CELLS. 2015 9 2177 26 EPIGENETIC MECHANISMS OF HYPERGLYCEMIC MEMORY. RECENTLY THE CONCEPT EMERGED THAT PROLONGED EXPOSURE TO ALTERED METABOLIC CONDITIONS, INCLUDING HYPERGLYCEMIA, MAY EPIGENETICALLY IMPRINT HUMAN CELLS PERMITTING VERTICAL OR HORIZONTAL TRANSFER TO "DESCENDANTS". ALTHOUGH MECHANISTICALLY ILL UNDERSTOOD, THE HYPERGLYCEMIC/EPIGENETIC MEMORY MAY REPRESENT ONE OF THE MAJOR LIMITATIONS FOR THE APPLICATION OF CELL THERAPY TO TREATMENT OF CHRONIC HEART DISEASE WHERE A RELATIVELY PROLONGED PERIOD OF EX VIVO CELLULAR EXPANSION IS REQUIRED. HYPERGLYCEMIC MEMORY, IN FACT, SEEMS TO CONTRIBUTE TO THE ESTABLISHMENT OF AN EPIGENETIC "REMINISCENCE" OF THE ALTERED METABOLIC STATE, TO WHICH, CELLS FROM DISEASED BODIES HAVE BEEN EXPOSED. THIS REVIEW SUMMARIZES THE MOST RELEVANT CONCEPTS AND OBSERVATIONS ABOUT THE MECHANISMS UNDERLYING THE ONSET OF STABLE INFORMATION INSIDE THE EPIGENOME LEADING TO THE DEVELOPMENT OF A DISEASED PHENOTYPE. SPECIAL ATTENTION IS GIVEN TO EPIGENETIC DRUGS AND HOW THEY HAVE BEEN USED IN EXPERIMENTAL, PRECLINICAL AND CLINICAL SETTINGS TO TREAT DYSMETABOLISM, DIABETES AND THEIR COMPLICATIONS. 2014 10 5974 36 TET1 IN NUCLEUS ACCUMBENS OPPOSES DEPRESSION- AND ANXIETY-LIKE BEHAVIORS. DEPRESSION IS A LEADING CAUSE OF DISEASE BURDEN, YET CURRENT THERAPIES FULLY TREAT <50% OF AFFECTED INDIVIDUALS. INCREASING EVIDENCE IMPLICATES EPIGENETIC MECHANISMS IN DEPRESSION AND ANTIDEPRESSANT ACTION. HERE WE EXAMINED A POSSIBLE ROLE FOR THE DNA DIOXYGENASE, TEN-ELEVEN TRANSLOCATION PROTEIN 1 (TET1), IN DEPRESSION-RELATED BEHAVIORAL ABNORMALITIES. WE APPLIED CHRONIC SOCIAL DEFEAT STRESS, AN ETHOLOGICALLY VALIDATED MOUSE MODEL OF DEPRESSION-LIKE BEHAVIORS, AND EXAMINED TET1 EXPRESSION CHANGES IN NUCLEUS ACCUMBENS (NAC), A KEY BRAIN REWARD REGION. WE SHOW DECREASED TET1 EXPRESSION IN NAC IN STRESS-SUSCEPTIBLE MICE ONLY. SURPRISINGLY, SELECTIVE KNOCKOUT OF TET1 IN NAC NEURONS OF ADULT MICE PRODUCED ANTIDEPRESSANT-LIKE EFFECTS IN SEVERAL BEHAVIORAL ASSAYS. TO IDENTIFY TET1 TARGETS THAT MEDIATE THESE ACTIONS, WE PERFORMED RNASEQ ON NAC AFTER CONDITIONAL DELETION OF TET1 AND FOUND THAT IMMUNE-RELATED GENES ARE THE MOST HIGHLY DYSREGULATED. MOREOVER, MANY OF THESE GENES ARE ALSO UPREGULATED IN THE NAC OF RESILIENT MICE AFTER CHRONIC SOCIAL DEFEAT STRESS. THESE FINDINGS REVEAL A NOVEL ROLE FOR TET1, AN ENZYME IMPORTANT FOR DNA HYDROXYMETHYLATION, IN THE BRAIN'S REWARD CIRCUITRY IN MODULATING STRESS RESPONSES IN MICE. WE ALSO IDENTIFY A SUBSET OF GENES THAT ARE REGULATED BY TET1 IN THIS CIRCUITRY. THESE FINDINGS PROVIDE NEW INSIGHT INTO THE PATHOPHYSIOLOGY OF DEPRESSION, WHICH CAN AID IN FUTURE ANTIDEPRESSANT DRUG DISCOVERY EFFORTS. 2017 11 434 49 ANTIDEPRESSANT-LIKE EFFECT OF SODIUM BUTYRATE IS ASSOCIATED WITH AN INCREASE IN TET1 AND IN 5-HYDROXYMETHYLATION LEVELS IN THE BDNF GENE. BACKGROUND: EPIGENETIC DRUGS LIKE SODIUM BUTYRATE (NAB) SHOW ANTIDEPRESSANT-LIKE EFFECTS IN PRECLINICAL STUDIES, BUT THE EXACT MOLECULAR MECHANISMS OF THE ANTIDEPRESSANT EFFECTS REMAIN UNKNOWN. WHILE RESEARCH USING NAB HAS MAINLY FOCUSED ON ITS ROLE AS A HISTONE DEACETYLASE INHIBITOR (HDACI), THERE IS ALSO EVIDENCE THAT NAB AFFECTS DNA METHYLATION. METHODS: THE PURPOSE OF THIS STUDY WAS TO EXAMINE NAB'S PUTATIVE ANTIDEPRESSANT-LIKE EFFICACY IN RELATION TO DNA METHYLATION CHANGES IN THE PREFRONTAL CORTEX OF AN ESTABLISHED GENETIC RAT MODEL OF DEPRESSION (THE FLINDERS SENSITIVE LINE [FSL]) AND ITS CONTROLS (THE FLINDERS RESISTANT LINE). RESULTS: THE FSL RATS HAD LOWER LEVELS OF TEN-ELEVEN TRANSLOCATION METHYLCYTOSINE DIOXYGENASE 1 (TET1), WHICH CATALYZES THE CONVERSION OF DNA METHYLATION TO HYDROXYMETHYLATION. AS INDICATED BY THE BEHAVIORAL DESPAIR TEST, CHRONIC ADMINISTRATION OF NAB HAD ANTIDEPRESSANT-LIKE EFFECTS IN THE FSL AND WAS ACCOMPANIED BY INCREASED LEVELS OF TET1. THE TET1 UPREGULATION WAS ALSO ASSOCIATED WITH AN INCREASE OF HYDROXYMETHYLATION AND A DECREASE OF METHYLATION IN BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF), A GENE ASSOCIATED WITH NEUROGENESIS AND SYNAPTIC PLASTICITY. THESE EPIGENETIC CHANGES WERE ASSOCIATED WITH A CORRESPONDING BDNF OVEREXPRESSION. CONCLUSIONS: OUR DATA SUPPORT THE ANTIDEPRESSANT EFFICACY OF HDACIS AND SUGGEST THAT THEIR EPIGENETIC EFFECTS MAY ALSO INCLUDE DNA METHYLATION CHANGES THAT ARE MEDIATED BY DEMETHYLATION-FACILITATING ENZYMES LIKE TET1. 2014 12 1332 48 DEPRESSIVE-LIKE PHENOTYPE INDUCED BY PRENATAL DEXAMETHASONE IN MICE IS REVERSED BY DESIPRAMINE. EXPOSURE TO PRENATAL INSULTS HAS BEEN ASSOCIATED WITH AN INCREASED RISK FOR NEUROPSYCHIATRIC DISORDERS, INCLUDING DEPRESSION, BUT THE MECHANISMS ARE STILL POORLY UNDERSTOOD. PERSISTENT ALTERATIONS OF THE HPA AXIS FEEDBACK MECHANISM AS WELL AS ADULT IMPAIRED NEUROGENESIS ARE BELIEVED TO PLAY A RELEVANT ROLE IN THE ETIOLOGY OF DEPRESSION. IN ADDITION, GROWING EVIDENCE POINTS AT EPIGENETIC REPROGRAMMING AS A KEY FACTOR. WE HAVE PREVIOUSLY SHOWN THAT PRENATAL EXPOSURE TO THE SYNTHETIC GLUCOCORTICOID DEXAMETHASONE (DEX) IMPAIRS NEUROGENESIS AND LEADS TO LATE ONSET OF DEPRESSION-LIKE BEHAVIOR THAT DOES NOT RESPOND TO THE SSRI ANTIDEPRESSANT FLUOXETINE (FLX). THE AIMS OF THIS STUDY WERE TO ASSESS THE EFFECT OF DEX PRENATAL EXPOSURE ON THE MORPHOLOGY OF HIPPOCAMPAL GRANULE NEURONS AND ON THE EXPRESSION OF GENES RELATED TO PLASTICITY; AND TO TEST WHETHER THE SNRI ANTIDEPRESSANT DESIPRAMINE (DMI), UNLIKE FLX, COULD COUNTERACT THE EFFECT OF PRENATAL-DEX. C57BL/6 MICE WERE EXPOSED TO DEX (0.05 MG/KG/DAY) IN UTERO AND RECEIVED INTRA-HIPPOCAMPAL INJECTION OF GFP EXPRESSING RETROVIRAL VECTOR FOR LABELING OF NEWBORN GRANULE CELLS AT ELEVEN MONTHS. BY TWELVE MONTHS, DEX MICE SHOWED DEPRESSION-LIKE BEHAVIOR ASSOCIATED WITH DECREASED NEUROGENESIS AND MORPHOLOGICAL ALTERATIONS OF THE NEWBORN GRANULE CELLS IN THE DENTATE GYRUS (DG). FURTHERMORE DEX MICE DISPLAYED ALTERED EXPRESSION OF GENES CONTROLLING NEUROGENESIS AND NEURONAL MORPHOLOGY, SUCH AS CDKN1C, P16, TRKB, DISC1 AND REELIN. CHRONIC TREATMENT WITH DMI LED TO A SIGNIFICANT DECREASE IN IMMOBILITY TIME IN THE FORCED SWIM TEST. IN ADDITION, DMI RESTORED NEUROGENESIS, NEURONAL MORPHOLOGY IN THE DG, AS WELL AS THE EXPRESSION OF ALL RELATED GENES. OUR RESULTS SUGGEST THAT (1) PRENATAL DEX INDUCES EARLY AND PERSISTENT REPROGRAMMING EFFECTS RESULTING IN ALTERED NEUROGENESIS AND NEURONAL MORPHOLOGY; AND (2) DMI TREATMENT REVERSES DEX-INDUCED DEPRESSION BY RESTORING THE EXPRESSION OF GENES RELEVANT TO NEURONAL PLASTICITY. 2017 13 5020 47 PERSISTENT OVEREXPRESSION OF DNA METHYLTRANSFERASE 1 ATTENUATING GABAERGIC INHIBITION IN BASOLATERAL AMYGDALA ACCOUNTS FOR ANXIETY IN RAT OFFSPRING EXPOSED PERINATALLY TO LOW-DOSE BISPHENOL A. 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. WE HAVE SHOWN THAT PERINATAL EXPOSURE TO BISPHENOL A (BPA) AT ENVIRONMENTAL DOSE LEVEL CAUSES LONG-TERM ANXIETY-LIKE BEHAVIORS IN RATS. THE AIM OF THIS STUDY WAS TO EXAMINE EPIGENETIC REPROGRAMMING EFFECT OF BPA ON ANXIETY-RELATED NEUROBEHAVIOR IN THE RAT OFFSPRING. THE RESULTS OF REAL-TIME RT-PCR DISPLAYED THAT THE OVEREXPRESSION OF DNA METHYLTRANSFERASE 1 (DNMT1) MRNA WAS ACCOMPANIED BY THE REDUCTION OF GLUTAMIC ACID DECARBOXYLASE 67 (GAD67) MRNA LEVEL IN THE BASOLATERAL AMYGDALA (BLA) OF POSTNATAL DAY 45 BPA-EXPOSED FEMALE RATS. CHRONIC INTRO-BLA INJECTION WITH 5-ADA-CDR COULD RECTIFY THE GAD67 MRNA EXPRESSION. BEHAVIORAL DATA SHOWED THAT THE ANXIETY-LIKE BEHAVIORS IN BPA-EXPOSED RATS WERE REVERSED BY INTRO-BLA TREATMENT WITH 5-ADA-CDR WHICH COULD BE FURTHER BLOCKED BY PTX. ELECTROPHYSIOLOGICAL STUDY REVEALED BEHAVIORAL ALTERATIONS WERE ASSOCIATED WITH THE INCREASE OF POSTSYNAPTIC NEURONAL EXCITABILITY IN THE CORTICAL-BLA PATHWAY WHICH APPEARED AS MULTISPIKE RESPONSES, PAIRED-PULSE FACILITATION INSTEAD OF PAIRED-PULSE INHIBITION AND LONG-TERM POTENTIATION AND 5-AZA-CDR TREATMENT RESTORED THE INCREASED SYNAPTIC TRANSMISSION IN THE BLA VIA IMPROVING GABAERGIC SYSTEM. THE ABOVE RESULTS SUGGEST THAT THE OVEREXPRESSION OF DNMT1 IN THE BLA IS RESPONSIBLE FOR THE ETIOLOGY OF ANXIETY ASSOCIATED WITH BPA EXPOSURE VIA GABAERGIC DISINHIBITION. IN ADDITION, WE ALSO FIND THESE LONG-TERM NEUROBEHAVIORAL EFFECTS OF DEVELOPMENTAL BPA EXPOSURE ARE REVERSIBLE IN ADOLESCENT PERIOD. 2013 14 4206 53 METABOTROPIC GLUTAMATE 2/3 RECEPTORS AND EPIGENETIC MODIFICATIONS IN PSYCHOTIC DISORDERS: A REVIEW. SCHIZOPHRENIA AND BIPOLAR DISORDER ARE CHRONIC PSYCHIATRIC DISORDERS, BOTH CONSIDERED AS "MAJOR PSYCHOSIS"; THEY ARE THOUGHT TO SHARE SOME PATHOGENETIC FACTORS INVOLVING A DYSFUNCTIONAL GENE X ENVIRONMENT INTERACTION. ALTERATIONS IN THE GLUTAMATERGIC TRANSMISSION HAVE BEEN SUGGESTED TO BE INVOLVED IN THE PATHOGENESIS OF PSYCHOSIS. OUR GROUP DEVELOPED AN EPIGENETIC MODEL OF SCHIZOPHRENIA ORIGINATED BY PRENATAL RESTRAINT STRESS (PRS) PARADIGM IN MICE. PRS MICE DEVELOPED SOME BEHAVIORAL ALTERATIONS OBSERVED IN SCHIZOPHRENIC PATIENTS AND CLASSIC ANIMAL MODELS OF SCHIZOPHRENIA, I.E. DEFICITS IN SOCIAL INTERACTION, LOCOMOTOR ACTIVITY AND PREPULSE INHIBITION. THEY ALSO SHOWED SPECIFIC CHANGES IN PROMOTER DNA METHYLATION ACTIVITY OF GENES RELATED TO SCHIZOPHRENIA SUCH AS REELIN, BDNF AND GAD67, AND ALTERED EXPRESSION AND FUNCTION OF MGLU2/3 RECEPTORS IN THE FRONTAL CORTEX. INTERESTINGLY, BEHAVIORAL AND MOLECULAR ALTERATIONS WERE REVERSED BY TREATMENT WITH MGLU2/3 AGONISTS. BASED ON THESE FINDINGS, WE SPECULATE THAT PHARMACOLOGICAL MODULATION OF THESE RECEPTORS COULD HAVE A GREAT IMPACT ON EARLY PHASE TREATMENT OF PSYCHOSIS TOGETHER WITH THE POSSIBILITY TO MODULATE SPECIFIC EPIGENETIC KEY PROTEIN INVOLVED IN THE DEVELOPMENT OF PSYCHOSIS. IN THIS REVIEW, WE WILL DISCUSS IN MORE DETAILS THE SPECIFIC FEATURES OF THE PRS MICE AS A SUITABLE EPIGENETIC MODEL FOR MAJOR PSYCHOSIS. WE WILL THEN FOCUS ON KEY PROTEINS OF CHROMATIN REMODELING MACHINERY AS POTENTIAL TARGET FOR NEW PHARMACOLOGICAL TREATMENT THROUGH THE ACTIVATION OF METABOTROPIC GLUTAMATE RECEPTORS. 2016 15 3520 30 IGLV3-21R110 IDENTIFIES AN AGGRESSIVE BIOLOGICAL SUBTYPE OF CHRONIC LYMPHOCYTIC LEUKEMIA WITH INTERMEDIATE EPIGENETICS. B-CELL RECEPTOR (BCR) SIGNALING IS CRUCIAL FOR CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) BIOLOGY. IGLV3-21-EXPRESSING B CELLS MAY ACQUIRE A SINGLE POINT MUTATION (R110) THAT TRIGGERS AUTONOMOUS BCR SIGNALING, CONFERRING AGGRESSIVE BEHAVIOR. EPIGENETIC STUDIES HAVE DEFINED 3 CLL SUBTYPES BASED ON METHYLATION SIGNATURES REMINISCENT OF NAIVE-LIKE (N-CLL), INTERMEDIATE (I-CLL), AND MEMORY-LIKE (M-CLL) B CELLS WITH DIFFERENT BIOLOGICAL FEATURES. I-CLL CARRIES A BORDERLINE IGHV MUTATIONAL LOAD AND SIGNIFICANTLY HIGHER USE OF IGHV3-21/IGLV3-21. TO DETERMINE THE CLINICAL AND BIOLOGICAL FEATURES OF IGLV3-21R110 CLL AND ITS RELATIONSHIP TO THESE EPIGENETIC SUBTYPES, WE CHARACTERIZED THE IMMUNOGLOBULIN GENE OF 584 CLL CASES USING WHOLE-GENOME/EXOME AND RNA SEQUENCING. IGLV3-21R110 WAS DETECTED IN 6.5% OF CASES: 30 (38%) OF 79 I-CLLS, 5 (1.7%) OF 291 M-CLLS, AND 1 (0.5%) OF 189 N-CLLS. ALL STEREOTYPE SUBSET 2 CASES CARRIED IGLV3-21R110, WHEREAS 62% OF IGLV3-21R110 I-CLL CASES HAD NONSTEREOTYPED BCR IMMUNOGLOBULINS. IGLV3-21R110 I-CLL HAD A SIGNIFICANTLY HIGHER NUMBER OF SF3B1 AND ATM MUTATIONS AND TOTAL NUMBER OF DRIVER ALTERATIONS. HOWEVER, THE R110 MUTATION WAS THE SOLE ALTERATION IN 1 I-CLL AND WAS ACCOMPANIED ONLY BY DEL(13Q) IN 3. ALTHOUGH IGHV MUTATIONAL STATUS VARIED, IGLV3-21R110 I-CLL TRANSCRIPTOMICALLY RESEMBLED N-CLL/UNMUTATED IGHV CLL WITH A SPECIFIC SIGNATURE INCLUDING WNT5A/B OVEREXPRESSION. IN CONTRAST, I-CLL LACKING IGLV3-21R110 MIRRORED M-CLL/MUTATED IGHV. PATIENTS WITH IGLV3-21R110 I-CLL HAD A SHORT TIME TO FIRST TREATMENT AND OVERALL SURVIVAL SIMILAR TO THOSE OF N-CLL/UNMUTATED IGHV PATIENTS, WHEREAS PATIENTS WITH NON-IGLV3-21R110 I-CLL HAD A GOOD PROGNOSIS SIMILAR TO THAT OF PATIENTS WITH M-CLL/MUTATED IGHV. IGLV3-21R110 DEFINES A CLL SUBGROUP WITH SPECIFIC BIOLOGICAL FEATURES AND AN UNFAVORABLE PROGNOSIS INDEPENDENT OF IGHV MUTATIONAL STATUS AND EPIGENETIC SUBTYPE. 2021 16 3969 44 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 17 2740 28 EXPOSURE TO EARLY LIFE STRESS RESULTS IN EPIGENETIC CHANGES IN NEUROTROPHIC FACTOR GENE EXPRESSION IN A PARKINSONIAN RAT MODEL. EARLY LIFE ADVERSITY INCREASES THE RISK OF MENTAL DISORDERS LATER IN LIFE. CHRONIC EARLY LIFE STRESS MAY ALTER NEUROTROPHIC FACTOR GENE EXPRESSION INCLUDING THOSE FOR BRAIN DERIVED NEUROTROPHIC FACTOR (BDNF) AND GLIAL CELL DERIVED NEUROTROPHIC FACTOR (GDNF) THAT ARE IMPORTANT IN NEURONAL GROWTH, SURVIVAL, AND MAINTENANCE. MATERNAL SEPARATION WAS USED IN THIS STUDY TO MODEL EARLY LIFE STRESS. FOLLOWING UNILATERAL INJECTION OF A MILD DOSE OF 6-HYDROXYDOPAMINE (6-OHDA), WE MEASURED CORTICOSTERONE (CORT) IN THE BLOOD AND STRIATUM OF STRESSED AND NONSTRESSED RATS; WE ALSO MEASURED DNA METHYLATION AND BDNF AND GDNF GENE EXPRESSION IN THE STRIATUM USING REAL TIME PCR. IN THE PRESENCE OF STRESS, WE FOUND THAT THERE WAS INCREASED CORTICOSTERONE CONCENTRATION IN BOTH BLOOD AND STRIATAL TISSUE. FURTHER TO THIS, WE FOUND HIGHER DNA METHYLATION AND DECREASED NEUROTROPHIC FACTOR GENE EXPRESSION. 6-OHDA LESION INCREASED NEUROTROPHIC FACTOR GENE EXPRESSION IN BOTH STRESSED AND NONSTRESSED RATS BUT THIS INCREASE WAS HIGHER IN THE NONSTRESSED RATS. OUR RESULTS SUGGEST THAT EXPOSURE TO EARLY POSTNATAL STRESS INCREASES CORTICOSTERONE CONCENTRATION WHICH LEADS TO INCREASED DNA METHYLATION. THIS EFFECT RESULTS IN DECREASED BDNF AND GDNF GENE EXPRESSION IN THE STRIATUM LEADING TO DECREASED PROTECTION AGAINST SUBSEQUENT INSULTS LATER IN LIFE. 2016 18 5121 20 POSSIBLE IMPRINTING AND MICROCHIMERISM IN CHRONIC LYMPHOCYTIC LEUKEMIA AND RELATED LYMPHOPROLIFERATIVE DISORDERS. BASED ON THE CONCEPT THAT THE TUMOROGENESIS IN CHRONIC LYMPHOCYTIC LEUKAEMIA COMPRISES BOTH AN INITIAL, INHERITED MUTATION AND SUBSEQUENT SOMATIC MUTATIONS, THE PLEIOTYPIC DIVERSITY OF FAMILIAL CHRONIC LYMPHOCYTIC LEUKAEMIA AND RELATED MALIGNANT LYMPHOPROLIFERATIVE DISORDERS IS GENERALLY EXPLAINED BY A REPERTOIRE OF MONOALLELIC POLYGENES IN THE INITIAL MUTATION. EPIGENETIC GENOMIC IMPRINTING IS A LIKELY MECHANISM BEHIND OF THE ASYNCHRONEOUS REPLICATING MONOALLELIC POLYGENES WHICH IS DISCUSSED IN THE LIGHT OF PLEIOTROPHY AND BIRTH ORDER EFFECT. FURTHERMORE, IT IS DISCUSSED THAT ONE POSSIBLE MECHANISM AVAILABLE FOR THE EPIGENETIC TRANSFER OF THESE GENES COULD BE THE PHYSIOLOGICAL PREGNANCY-RELATED MICROCHIMERISM BETWEEN MOTHER AND FETUS. 2008 19 1809 45 EFFECTS OF ANTIPSYCHOTIC DRUGS ON THE EPIGENETIC MODIFICATION OF BRAIN-DERIVED NEUROTROPHIC FACTOR GENE EXPRESSION IN THE HIPPOCAMPI OF CHRONIC RESTRAINT STRESS RATS. RECENT STUDIES HAVE SHOWN THAT ANTIPSYCHOTIC DRUGS HAVE EPIGENETIC EFFECTS. HOWEVER, THE EFFECTS OF ANTIPSYCHOTIC DRUGS ON HISTONE MODIFICATION REMAIN UNCLEAR. THEREFORE, WE INVESTIGATED THE EFFECTS OF ANTIPSYCHOTIC DRUGS ON THE EPIGENETIC MODIFICATION OF THE BDNF GENE IN THE RAT HIPPOCAMPUS. RATS WERE SUBJECTED TO CHRONIC RESTRAINT STRESS (6 H/D FOR 21 D) AND THEN WERE ADMINISTERED WITH EITHER OLANZAPINE (2 MG/KG) OR HALOPERIDOL (1 MG/KG). THE LEVELS OF HISTONE H3 ACETYLATION AND MECP2 BINDING AT BDNF PROMOTER IV WERE ASSESSED WITH CHROMATIN IMMUNOPRECIPITATION ASSAYS. THE MRNA LEVELS OF TOTAL BDNF WITH EXON IV, HDAC5, DNMT1, AND DNMT3A WERE ASSESSED WITH A QUANTITATIVE RT-PCR PROCEDURE. CHRONIC RESTRAINT STRESS RESULTED IN THE DOWNREGULATION OF TOTAL AND EXON IV BDNF MRNA LEVELS AND A DECREASE IN HISTONE H3 ACETYLATION AND AN INCREASE IN MECP2 BINDING AT BDNF PROMOTER IV. FURTHERMORE, THERE WERE ROBUST INCREASES IN THE EXPRESSION OF HDAC5 AND DNMTS. OLANZAPINE ADMINISTRATION LARGELY PREVENTED THESE CHANGES. THE ADMINISTRATION OF HALOPERIDOL HAD NO EFFECT. THESE FINDINGS SUGGEST THAT THE ANTIPSYCHOTIC DRUG OLANZAPINE INDUCED HISTONE MODIFICATION OF BDNF GENE EXPRESSION IN THE HIPPOCAMPUS AND THAT THESE EPIGENETIC ALTERATIONS MAY REPRESENT ONE OF THE MECHANISMS UNDERLYING THE ACTIONS OF ANTIPSYCHOTIC DRUGS. 2018 20 4218 43 METHYL SUPPLEMENTATION ATTENUATES COCAINE-SEEKING BEHAVIORS AND COCAINE-INDUCED C-FOS ACTIVATION IN A DNA METHYLATION-DEPENDENT MANNER. EPIGENETIC MECHANISMS, SUCH AS HISTONE MODIFICATIONS, REGULATE RESPONSIVENESS TO DRUGS OF ABUSE, SUCH AS COCAINE, BUT RELATIVELY LITTLE IS KNOWN ABOUT THE REGULATION OF ADDICTIVE-LIKE BEHAVIORS BY DNA METHYLATION. TO INVESTIGATE THE INFLUENCE OF DNA METHYLATION ON THE LOCOMOTOR-ACTIVATING EFFECTS OF COCAINE AND ON DRUG-SEEKING BEHAVIOR, RATS RECEIVING METHYL SUPPLEMENTATION VIA CHRONIC L-METHIONINE (MET) UNDERWENT EITHER A SENSITIZATION REGIMEN OF INTERMITTENT COCAINE INJECTIONS OR INTRAVENOUS SELF-ADMINISTRATION OF COCAINE, FOLLOWED BY CUE-INDUCED AND DRUG-PRIMED REINSTATEMENT. MET BLOCKED SENSITIZATION TO THE LOCOMOTOR-ACTIVATING EFFECTS OF COCAINE AND ATTENUATED DRUG-PRIMED REINSTATEMENT, WITH NO EFFECT ON CUE-INDUCED REINSTATEMENT OR SUCROSE SELF-ADMINISTRATION AND REINSTATEMENT. FURTHERMORE, UPREGULATION OF DNA METHYLTRANSFERASE 3A AND 3B AND GLOBAL DNA HYPOMETHYLATION WERE OBSERVED IN THE NUCLEUS ACCUMBENS CORE (NAC), BUT NOT IN THE MEDIAL PREFRONTAL CORTEX (MPFC), OF COCAINE-PRETREATED RATS. GLUTAMATERGIC PROJECTIONS FROM THE MPFC TO THE NAC ARE CRITICALLY INVOLVED IN THE REGULATION OF COCAINE-PRIMED REINSTATEMENT, AND ACTIVATION OF BOTH BRAIN REGIONS IS SEEN IN HUMAN ADDICTS WHEN REEXPOSED TO THE DRUG. WHEN COMPARED WITH VEHICLE-PRETREATED RATS, THE IMMEDIATE EARLY GENE C-FOS (A MARKER OF NEURONAL ACTIVATION) WAS UPREGULATED IN THE NAC AND MPFC OF COCAINE-PRETREATED RATS AFTER COCAINE-PRIMED REINSTATEMENT, AND CHRONIC MET TREATMENT BLOCKED ITS INDUCTION IN BOTH REGIONS. COCAINE-INDUCED C-FOS EXPRESSION IN THE NAC WAS ASSOCIATED WITH REDUCED METHYLATION AT CPG DINUCLEOTIDES IN THE C-FOS GENE PROMOTER, EFFECTS REVERSED BY MET TREATMENT. OVERALL, THESE DATA SUGGEST THAT DRUG-SEEKING BEHAVIORS ARE, IN PART, ATTRIBUTABLE TO A DNA METHYLATION-DEPENDENT PROCESS, LIKELY OCCURRING AT SPECIFIC GENE LOCI (E.G., C-FOS) IN THE REWARD PATHWAY. 2015