1 5661 101 SEXUAL DIMORPHISM IN EPIGENOMIC RESPONSES OF STEM CELLS TO EXTREME FETAL GROWTH. EXTREME FETAL GROWTH IS ASSOCIATED WITH INCREASED SUSCEPTIBILITY TO A RANGE OF ADULT DISEASES THROUGH AN UNKNOWN MECHANISM OF CELLULAR MEMORY. WE TESTED WHETHER HERITABLE EPIGENETIC PROCESSES IN LONG-LIVED CD34(+) HAEMATOPOIETIC STEM/PROGENITOR CELLS SHOWED EVIDENCE FOR RE-PROGRAMMING ASSOCIATED WITH THE EXTREMES OF FETAL GROWTH. HERE WE SHOW THAT BOTH FETAL GROWTH RESTRICTION AND OVER-GROWTH ARE ASSOCIATED WITH GLOBAL SHIFTS TOWARDS DNA HYPERMETHYLATION, TARGETING CIS-REGULATORY ELEMENTS IN PROXIMITY TO GENES INVOLVED IN GLUCOSE HOMEOSTASIS AND STEM CELL FUNCTION. WE FIND A SEXUALLY DIMORPHIC RESPONSE; INTRAUTERINE GROWTH RESTRICTION IS ASSOCIATED WITH SUBSTANTIALLY GREATER EPIGENETIC DYSREGULATION IN MALES, WHEREAS LARGE FOR GESTATIONAL AGE GROWTH PREDOMINANTLY AFFECTS FEMALES. THE FINDINGS ARE CONSISTENT WITH EXTREME FETAL GROWTH INTERACTING WITH VARIABLE FETAL SUSCEPTIBILITY TO INFLUENCE CELLULAR AGEING AND METABOLIC CHARACTERISTICS THROUGH EPIGENETIC MECHANISMS, POTENTIALLY GENERATING BIOMARKERS THAT COULD IDENTIFY INFANTS AT HIGHER RISK FOR CHRONIC DISEASE LATER IN LIFE. 2014 2 1520 33 DNA METHYLATION AT DIFFERENTIALLY METHYLATED REGIONS OF IMPRINTED GENES IS RESISTANT TO DEVELOPMENTAL PROGRAMMING BY MATERNAL NUTRITION. THE NUTRITIONAL ENVIRONMENT IN WHICH THE MAMMALIAN FETUS OR INFANT DEVELOP IS RECOGNIZED AS INFLUENCING THE RISK OF CHRONIC DISEASES, SUCH AS TYPE 2 DIABETES AND HYPERTENSION, IN A PHENOMENON THAT HAS BECOME KNOWN AS DEVELOPMENTAL PROGRAMMING. THE LATE ONSET OF SUCH DISEASES IN RESPONSE TO EARLIER TRANSIENT EXPERIENCES HAS LED TO THE SUGGESTION THAT DEVELOPMENTAL PROGRAMMING MAY HAVE AN EPIGENETIC COMPONENT, BECAUSE EPIGENETIC MARKS SUCH AS DNA METHYLATION OR HISTONE TAIL MODIFICATIONS COULD PROVIDE A PERSISTENT MEMORY OF EARLIER NUTRITIONAL STATES. ONE CLASS OF GENES THAT HAS BEEN CONSIDERED A POTENTIAL TARGET OR MEDIATOR OF PROGRAMMING EVENTS IS IMPRINTED GENES, BECAUSE THESE GENES CRITICALLY DEPEND UPON EPIGENETIC MODIFICATIONS FOR CORRECT EXPRESSION AND BECAUSE MANY IMPRINTED GENES HAVE ROLES IN CONTROLLING FETAL GROWTH AS WELL AS NEONATAL AND ADULT METABOLISM. IN THIS STUDY, WE HAVE USED AN ESTABLISHED MODEL OF DEVELOPMENTAL PROGRAMMING-ISOCALORIC PROTEIN RESTRICTION TO FEMALE MICE DURING GESTATION OR LACTATION-TO EXAMINE WHETHER THERE ARE EFFECTS ON EXPRESSION AND DNA METHYLATION OF IMPRINTED GENES IN THE OFFSPRING. WE FIND THAT ALTHOUGH EXPRESSION OF SOME IMPRINTED GENES IN LIVER OF OFFSPRING IS ROBUSTLY AND SUSTAINABLY CHANGED, METHYLATION OF THE DIFFERENTIALLY METHYLATED REGIONS (DMRS) THAT CONTROL THEIR MONOALLELIC EXPRESSION REMAINS LARGELY UNALTERED. WE CONCLUDE THAT DEREGULATION OF IMPRINTING THROUGH A GENERAL EFFECT ON DMR METHYLATION IS UNLIKELY TO BE A COMMON FACTOR IN DEVELOPMENTAL PROGRAMMING. 2012 3 4496 21 MORE THAN GENES: THE ADVANCED FETAL PROGRAMMING HYPOTHESIS. MANY LINES OF DATA, INITIAL EPIDEMIOLOGIC STUDIES AS WELL AS SUBSEQUENT EXTENSIVE EXPERIMENTAL STUDIES, INDICATE THAT EARLY-LIFE EVENTS PLAY A POWERFUL ROLE IN INFLUENCING LATER SUCEPTIBILITY TO CERTAIN CHRONIC DISEASES. SUCH EVENTS MIGHT BE OVER- OR UNDERNUTRITION, EXPOSURE TO ENVIRONMENTAL TOXINS, BUT ALSO CHANGES IN HORMONES, IN PARTICULAR STRESS HORMONES. TYPICALLY, THOSE EVENTS ARE TRIGGERED BY THE ENVIRONMENTAL CHALLENGES OF THE MOTHER. HOWEVER, RECENT STUDIES HAVE SHOWN THAT PATERNAL ENVIRONMENTAL OR NUTRITIONAL FACTORS AFFECT THE PHENOTYPE OF THE OFFSPRING AS WELL. THE MATERNAL AND PATERNAL ENVIRONMENTAL FACTORS ACT ON THE PHENOTYPE OF THE OFFSPRING VIA EPIGENETIC MODIFICATION OF ITS GENOME. THE ADVANCED FETAL PROGRAMMING HYPOTHESIS PROPOSES AN ADDITIONAL NON-ENVIRONMENTALLY DRIVEN MECHANISM: MATERNAL AND ALSO PATERNAL GENES MAY INFLUENCE THE MATURATING SPERM, THE OOCYTE, AND LATER THE EMBRYO/FETUS, LEADING TO THEIR EPIGENETIC ALTERATION. THUS, THE OBSERVED PHENOTYPE OF THE OFFSPRING MAY BE ALTERED BY MATERNAL/PATERNAL GENES INDEPENDENT OF THE FETAL GENOME. MEANWHILE, SEVERAL INDEPENDENT ASSOCIATION STUDIES IN HUMANS DEALING WITH METABOLIC AND NEUROLOGICAL TRAITS ALSO SUGGEST THAT MATERNAL GENES MIGHT AFFECT THE OFFSPRING PHENOTYPE INDEPENDENT OF THE TRANSMISSION OF THAT PARTICULAR GENE TO THE OFFSPRING. CONSIDERING THE IMPLICATIONS OF THIS HYPOTHESIS, SOME CONCLUSIONS DRAWN FROM TRANSGENIC OR KNOCKOUT ANIMAL MODELS AND BASED ON THE CAUSALITY BETWEEN A GENETIC ALTERATION AND A PHENOTYPE, NEED TO BE CHALLENGED. POSSIBLE IMPLICATIONS FOR THE DEVELOPMENT, DIAGNOSTIC AND THERAPY OF HUMAN GENETIC DISEASES HAVE TO BE INVESTIGATED. 2014 4 2183 33 EPIGENETIC MECHANISMS RESPONSIBLE FOR THE TRANSGENERATIONAL INHERITANCE OF INTRAUTERINE GROWTH RESTRICTION PHENOTYPES. A POORLY FUNCTIONING PLACENTA RESULTS IN IMPAIRED EXCHANGES OF OXYGEN, NUTRITION, WASTES AND HORMONES BETWEEN THE MOTHER AND HER FETUS. THIS CAN LEAD TO RESTRICTION OF FETAL GROWTH. THESE GROWTH RESTRICTED BABIES ARE AT INCREASED RISK OF DEVELOPING CHRONIC DISEASES, SUCH AS TYPE-2 DIABETES, HYPERTENSION, AND KIDNEY DISEASE, LATER IN LIFE. ANIMAL STUDIES HAVE SHOWN THAT GROWTH RESTRICTED PHENOTYPES ARE SEX-DEPENDENT AND CAN BE TRANSMITTED TO SUBSEQUENT GENERATIONS THROUGH BOTH THE PATERNAL AND MATERNAL LINEAGES. ALTERED EPIGENETIC MECHANISMS, SPECIFICALLY CHANGES IN DNA METHYLATION, HISTONE MODIFICATIONS, AND NON-CODING RNAS THAT REGULATE EXPRESSION OF GENES THAT ARE IMPORTANT FOR FETAL DEVELOPMENT HAVE BEEN SHOWN TO BE ASSOCIATED WITH THE TRANSMISSION PATTERN OF GROWTH RESTRICTED PHENOTYPES. THIS REVIEW WILL DISCUSS THE SUBSEQUENT HEALTH OUTCOMES IN THE OFFSPRING AFTER GROWTH RESTRICTION AND THE TRANSMISSION PATTERNS OF THESE DISEASES. EVIDENCE OF ALTERED EPIGENETIC MECHANISMS IN ASSOCIATION WITH FETAL GROWTH RESTRICTION WILL ALSO BE REVIEWED. 2022 5 2274 28 EPIGENETIC REGULATION AND FETAL PROGRAMMING. FETAL PROGRAMMING ENCOMPASSES THE ROLE OF DEVELOPMENTAL PLASTICITY IN RESPONSE TO ENVIRONMENTAL AND NUTRITIONAL SIGNALS DURING EARLY LIFE AND ITS POTENTIAL ADVERSE CONSEQUENCES (RISK OF CARDIOVASCULAR, METABOLIC AND BEHAVIOURAL DISEASES) IN LATER LIFE. THE FIRST STUDIES IN THIS FIELD HIGHLIGHTED AN ASSOCIATION BETWEEN POOR FETAL GROWTH AND CHRONIC ADULT DISEASES. HOWEVER, ENVIRONMENTAL SIGNALS DURING EARLY LIFE MAY LEAD TO ADVERSE LONG-TERM EFFECTS INDEPENDENTLY OF OBVIOUS EFFECTS ON FETAL GROWTH. ADVERSE LONG-TERM EFFECTS REFLECT A MISMATCH BETWEEN EARLY (FETAL AND NEONATAL) ENVIRONMENTAL CONDITIONS AND THE CONDITIONS THAT THE INDIVIDUAL WILL CONFRONT LATER IN LIFE. THE MECHANISMS UNDERLYING THIS RISK REMAIN UNCLEAR. HOWEVER, EXPERIMENTAL DATA IN RODENTS AND RECENT OBSERVATIONS IN HUMANS SUGGEST THAT EPIGENETIC CHANGES IN REGULATORY GENES AND GROWTH-RELATED GENES PLAY A SIGNIFICANT ROLE IN FETAL PROGRAMMING. IMPROVEMENTS IN OUR UNDERSTANDING OF THE BIOCHEMICAL AND MOLECULAR MECHANISMS AT PLAY IN FETAL PROGRAMMING WOULD MAKE IT POSSIBLE TO IDENTIFY BIOMARKERS FOR DETECTING INFANTS AT HIGH RISK OF ADULT-ONSET DISEASES. SUCH IMPROVEMENTS SHOULD ALSO LEAD TO THE DEVELOPMENT OF PREVENTIVE AND THERAPEUTIC STRATEGIES. 2008 6 1371 28 DEVELOPMENTAL ORIGINS OF HEALTH AND DISEASE: NEW INSIGHTS. EPIDEMIOLOGICAL AND ANIMAL STUDIES SHOW THAT SMALL CHANGES IN THE DEVELOPMENTAL ENVIRONMENT CAN INDUCE PHENOTYPIC CHANGES AFFECTING AN INDIVIDUAL'S RESPONSES TO THEIR LATER ENVIRONMENT. THESE MAY ALTER THE RISK OF CHRONIC DISEASE SUCH AS METABOLIC SYNDROME OR CARDIOVASCULAR DISEASE. RECENT RESEARCH SHOWS THAT ANIMALS EXPOSED TO SUCH A MISMATCH BETWEEN PRENATAL AND POSTNATAL ENVIRONMENT DEVELOP OBESITY, REDUCED ACTIVITY, LEPTIN AND INSULIN RESISTANCE, ELEVATED BLOOD PRESSURE AND VASCULAR ENDOTHELIAL DYSFUNCTION. EPIGENETIC PROCESSES ARE INVOLVED IN SUCH EFFECTS, TARGETED TO PROMOTER REGIONS OF SPECIFIC GENES IN SPECIFIC TISSUES. SUCH FINE CONTROL OF GENE EXPRESSION SUGGESTS THAT THE MECHANISMS HAVE BEEN RETAINED THROUGH EVOLUTION THROUGH THEIR ADAPTIVE ADVANTAGE, RATHER THAN REPRESENTING EXTREME EFFECTS OF DEVELOPMENTAL DISRUPTION AKIN TO TERATOGENESIS. THERE MAY BE ADAPTIVE ADVANTAGE IN A DEVELOPMENTAL CUE INDUCING A PHENOTYPIC CHANGE IN GENERATIONS BEYOND THE IMMEDIATE PREGNANCY, AND A RANGE OF DATA THAT SUPPORT THIS CONCEPT. IN ANIMALS, EPIGENETIC EFFECTS SUCH AS DNA METHYLATION CAN BE PASSED TO SUCCESSIVE GENERATIONS. ENVIRONMENTAL TOXINS, INCLUDING ENDOCRINE DISRUPTORS, MAY INDUCE GREATER RISK OF CHRONIC DISEASE, EVEN AT LOW EXPOSURE LEVELS, IF THEY AFFECT SUCH NORMAL DEVELOPMENTAL EPIGENETIC PROCESSES. APPROPRIATE INTERVENTIONS MAY HAVE LONG-TERM MULTIGENERATIONAL EFFECTS TO REDUCE THE RISK OF CHRONIC DISEASE. 2008 7 4767 24 NUCLEAR AND MITOCHONDRIAL DNA ALTERATIONS IN NEWBORNS WITH PRENATAL EXPOSURE TO CIGARETTE SMOKE. NEWBORNS EXPOSED TO MATERNAL CIGARETTE SMOKE (CS) IN UTERO HAVE AN INCREASED RISK OF DEVELOPING CHRONIC DISEASES, CANCER, AND ACQUIRING DECREASED COGNITIVE FUNCTION IN ADULTHOOD. ALTHOUGH THE LITERATURE REPORTS MANY DELETERIOUS EFFECTS ASSOCIATED WITH MATERNAL CIGARETTE SMOKING ON THE FETUS, THE MOLECULAR ALTERATIONS AND MECHANISMS OF ACTION ARE NOT YET CLEAR. SMOKING MAY ACT DIRECTLY ON NUCLEAR DNA BY INDUCING MUTATIONS OR EPIGENETIC MODIFICATIONS. RECENT STUDIES ALSO INDICATE THAT SMOKING MAY ACT ON MITOCHONDRIAL DNA BY INDUCING A CHANGE IN THE NUMBER OF COPIES TO MAKE UP FOR THE DAMAGE CAUSED BY SMOKING ON THE RESPIRATORY CHAIN AND LACK OF ENERGY. IN ADDITION, INDIVIDUAL GENETIC SUSCEPTIBILITY PLAYS A SIGNIFICANT ROLE IN DETERMINING THE EFFECTS OF SMOKING DURING DEVELOPMENT. FURTHERMORE, PRIOR EXPOSURE OF PATERNAL AND MATERNAL GAMETES TO CIGARETTE SMOKE MAY AFFECT THE HEALTH OF THE DEVELOPING INDIVIDUAL, NOT ONLY THE IN UTERO EXPOSURE. THIS REVIEW EXAMINES THE GENETIC AND EPIGENETIC ALTERATIONS IN NUCLEAR AND MITOCHONDRIAL DNA ASSOCIATED WITH SMOKE EXPOSURE DURING THE MOST SENSITIVE PERIODS OF DEVELOPMENT (PRIOR TO CONCEPTION, PRENATAL AND EARLY POSTNATAL) AND ASSESSES HOW SUCH CHANGES MAY HAVE CONSEQUENCES FOR BOTH FETAL GROWTH AND DEVELOPMENT. 2015 8 3848 28 IS EPIGENETICS AN IMPORTANT LINK BETWEEN EARLY LIFE EVENTS AND ADULT DISEASE? BACKGROUND: EPIGENETIC MECHANISMS PROVIDE ONE POTENTIAL EXPLANATION FOR HOW ENVIRONMENTAL INFLUENCES IN EARLY LIFE CAUSE LONG-TERM CHANGES IN CHRONIC DISEASE SUSCEPTIBILITY. WHEREAS EPIGENETIC DYSREGULATION IS INCREASINGLY IMPLICATED IN VARIOUS RARE DEVELOPMENTAL SYNDROMES AND CANCER, THE ROLE OF EPIGENETICS IN COMPLEX CHRONIC DISEASES, SUCH AS CARDIOVASCULAR DISEASE, TYPE 2 DIABETES AND OBESITY, REMAINS LARGELY UNCHARACTERIZED. EXTENSIVE WORK IN ANIMAL MODELS IS REQUIRED TO DEVELOP SPECIFIC HYPOTHESES THAT CAN BE PRACTICABLY TESTED IN HUMANS. ANIMAL MODELS: WE HAVE DEVELOPED A MOUSE MODEL SHOWING THAT METHYL DONOR SUPPLEMENTATION PREVENTS TRANSGENERATIONAL AMPLIFICATION OF OBESITY, SUGGESTING A ROLE FOR DNA METHYLATION IN THE DEVELOPMENTAL ESTABLISHMENT OF BODY WEIGHT REGULATION. CONCLUSIONS: COUPLING SUCH MODELS WITH RECENTLY DEVELOPED EPIGENOMIC TECHNOLOGIES SHOULD ULTIMATELY ENABLE US TO DETERMINE IF EPIGENETICS IS AN IMPORTANT LINK BETWEEN EARLY LIFE EVENTS AND ADULT DISEASE. 2009 9 2038 25 EPIGENETIC CHANGES PREDISPOSING TO TYPE 2 DIABETES IN INTRAUTERINE GROWTH RETARDATION. EPIDEMIOLOGIC STUDIES HAVE DEMONSTRATED AN ASSOCIATION BETWEEN INTRAUTERINE GROWTH RETARDATION AND A GREATER RISK OF CHRONIC DISEASE, INCLUDING CORONARY HEART DISEASE, HYPERTENSION, STROKE, AND TYPE 2 DIABETES IN ADULTHOOD. AN ADVERSE INTRAUTERINE ENVIRONMENT MAY AFFECT BOTH GROWTH AND DEVELOPMENT OF THE ORGANISM, PERMANENTLY PROGRAMMING ENDOCRINE AND METABOLIC FUNCTIONS. ONE OF THE MECHANISMS OF PROGRAMMING IS THE EPIGENETIC MODIFICATION OF GENE PROMOTERS INVOLVED IN THE CONTROL OF KEY METABOLIC PATHWAYS. THE AIM OF THIS REVIEW IS TO PROVIDE AN OVERVIEW OF THE EXPERIMENTAL EVIDENCE SHOWING THE EFFECTS OF EARLY EXPOSURE TO SUBOPTIMAL ENVIRONMENT ON EPIGENOME. THE KNOWLEDGE OF THE EPIGENETIC MARKERS OF PROGRAMMING MAY ALLOW THE IDENTIFICATION OF SUSCEPTIBLE INDIVIDUALS AND THE DESIGN OF TARGETED PREVENTION STRATEGIES. 2010 10 6133 26 THE EPIGENETIC ROLE OF VITAMIN C IN NEURODEVELOPMENT. THE MATERNAL DIET DURING PREGNANCY IS A KEY DETERMINANT OF OFFSPRING HEALTH. EARLY STUDIES HAVE LINKED POOR MATERNAL NUTRITION DURING GESTATION WITH A PROPENSITY FOR THE DEVELOPMENT OF CHRONIC CONDITIONS IN OFFSPRING. THESE CONDITIONS INCLUDE CARDIOVASCULAR DISEASE, TYPE 2 DIABETES AND EVEN COMPROMISED MENTAL HEALTH. WHILE MULTIPLE FACTORS MAY CONTRIBUTE TO THESE OUTCOMES, DISTURBED EPIGENETIC PROGRAMMING DURING EARLY DEVELOPMENT IS ONE POTENTIAL BIOLOGICAL MECHANISM. THE EPIGENOME IS PROGRAMMED PRIMARILY IN UTERO, AND DURING THIS TIME, THE DEVELOPING FETUS IS HIGHLY SUSCEPTIBLE TO ENVIRONMENTAL FACTORS SUCH AS NUTRITIONAL INSULTS. DURING NEURODEVELOPMENT, EPIGENETIC PROGRAMMING COORDINATES THE FORMATION OF PRIMITIVE CENTRAL NERVOUS SYSTEM STRUCTURES, NEUROGENESIS, AND NEUROPLASTICITY. DYSREGULATED EPIGENETIC PROGRAMMING HAS BEEN IMPLICATED IN THE AETIOLOGY OF SEVERAL NEURODEVELOPMENTAL DISORDERS SUCH AS TATTON-BROWN-RAHMAN SYNDROME. ACCORDINGLY, THERE IS GREAT INTEREST IN DETERMINING HOW MATERNAL NUTRIENT AVAILABILITY IN PREGNANCY MIGHT AFFECT THE EPIGENETIC STATUS OF OFFSPRING, AND HOW SUCH INFLUENCES MAY PRESENT PHENOTYPICALLY. IN RECENT YEARS, A NUMBER OF EPIGENETIC ENZYMES THAT ARE ACTIVE DURING EMBRYONIC DEVELOPMENT HAVE BEEN FOUND TO REQUIRE VITAMIN C AS A COFACTOR. THESE ENZYMES INCLUDE THE TEN-ELEVEN TRANSLOCATION METHYLCYTOSINE DIOXYGENASES (TETS) AND THE JUMONJI C DOMAIN-CONTAINING HISTONE LYSINE DEMETHYLASES THAT CATALYSE THE OXIDATIVE REMOVAL OF METHYL GROUPS ON CYTOSINES AND HISTONE LYSINE RESIDUES, RESPECTIVELY. THESE ENZYMES ARE INTEGRAL TO EPIGENETIC REGULATION AND HAVE FUNDAMENTAL ROLES IN CELLULAR DIFFERENTIATION, THE MAINTENANCE OF PLURIPOTENCY AND DEVELOPMENT. THE DEPENDENCE OF THESE ENZYMES ON VITAMIN C FOR OPTIMAL CATALYTIC ACTIVITY ILLUSTRATES A POTENTIALLY CRITICAL CONTRIBUTION OF THE NUTRIENT DURING MAMMALIAN DEVELOPMENT. THESE INSIGHTS ALSO HIGHLIGHT A POTENTIAL RISK ASSOCIATED WITH VITAMIN C INSUFFICIENCY DURING PREGNANCY. THE LINK BETWEEN VITAMIN C INSUFFICIENCY AND DEVELOPMENT IS PARTICULARLY APPARENT IN THE CONTEXT OF NEURODEVELOPMENT AND HIGH VITAMIN C CONCENTRATIONS IN THE BRAIN ARE INDICATIVE OF IMPORTANT FUNCTIONAL REQUIREMENTS IN THIS ORGAN. ACCORDINGLY, THIS REVIEW CONSIDERS THE EVIDENCE FOR THE POTENTIAL IMPACT OF MATERNAL VITAMIN C STATUS ON NEURODEVELOPMENTAL EPIGENETICS. 2022 11 1929 26 ENVIRONMENTAL EXPOSURE, DNA METHYLATION, AND GENE REGULATION: LESSONS FROM DIETHYLSTILBESTEROL-INDUCED CANCERS. DNA METHYLATION IS AN EPIGENETIC MECHANISM THAT REGULATES CHROMOSOMAL STABILITY AND GENE EXPRESSION. ABNORMAL DNA METHYLATION PATTERNS HAVE BEEN OBSERVED IN MANY TYPES OF HUMAN TUMORS, INCLUDING THOSE OF THE BREAST, PROSTATE, COLON, THYROID, STOMACH, UTERUS, AND CERVIX. WE AND OTHERS HAVE SHOWN THAT EXPOSURE TO A WIDE VARIETY OF XENOBIOTICS DURING CRITICAL PERIODS OF MAMMALIAN DEVELOPMENT CAN PERSISTENTLY ALTER THE PATTERN OF DNA METHYLATION, RESULTING IN POTENTIALLY ADVERSE BIOLOGICAL EFFECTS SUCH AS ABERRANT GENE EXPRESSION. THUS, THIS EPIGENETIC MECHANISM MAY UNDERLIE THE OBSERVED INCREASED RISK IN ADULTHOOD OF SEVERAL CHRONIC DISEASES, INCLUDING CANCER, IN RESPONSE TO XENOBIOTIC EXPOSURES EARLY IN LIFE. WE PRESENT HERE THE LESSONS LEARNED FROM STUDIES ON THE EFFECTS OF PERINATAL DIETHYLSTILBESTEROL (DES) EXPOSURE ON THE METHYLATION PATTERN OF THE PROMOTERS OF SEVERAL ESTROGEN-RESPONSIVE GENES ASSOCIATED WITH THE DEVELOPMENT OF REPRODUCTIVE ORGANS. PERINATAL DES EXPOSURE, WHICH INDUCES EPITHELIAL TUMORS OF THE UTERUS IN MICE AND IS ASSOCIATED WITH SEVERAL REPRODUCTIVE TRACT ABNORMALITIES AND INCREASED VAGINAL AND CERVICAL CANCER RISK IN WOMEN, PROVIDES A CLEAR EXAMPLE OF HOW ESTROGENIC XENOBIOTIC EXPOSURE DURING A CRITICAL PERIOD OF DEVELOPMENT CAN ABNORMALLY DEMETHYLATE DNA SEQUENCES DURING ORGAN DEVELOPMENT AND POSSIBLY INCREASE CANCER RISK LATER IN LIFE. IN ADDITION, NUTRITIONAL FACTORS AND STRESS MAY ALSO ALTER DNA METHYLATION DURING EARLY LIFE AND MODULATE THE RISK OF CANCER AND OTHER CHRONIC DISEASES IN ADULTHOOD. WE SUGGEST THAT DNA METHYLATION STATUS MAY BE INFLUENCED BY ENVIRONMENTAL EXPOSURES IN EARLY LIFE, LEADING TO INCREASED RISK OF CANCER IN ADULTHOOD. 2003 12 4125 28 MECHANISMS OF DISEASE: IN UTERO PROGRAMMING IN THE PATHOGENESIS OF HYPERTENSION. NUTRITIONAL AND OTHER ENVIRONMENTAL CUES DURING DEVELOPMENT CAN PERMANENTLY ALTER THE STRUCTURE, HOMEOSTATIC SYSTEMS, AND FUNCTIONS OF THE BODY. THIS PHENOMENON HAS BEEN REFERRED TO AS 'PROGRAMMING'. EPIDEMIOLOGICAL AND ANIMAL STUDIES SHOW THAT PROGRAMMED EFFECTS OPERATE WITHIN THE NORMAL RANGE OF GROWTH AND DEVELOPMENT, AND INFLUENCE THE RISK OF CHRONIC DISEASE IN ADULT LIFE. WE REVIEW THE EVIDENCE THAT THESE EFFECTS INCLUDE REDUCED NEPHRON NUMBER AND COMPENSATORY ADAPTATIONS, WHICH MIGHT LEAD TO HYPERTENSION, AND PERHAPS ACCELERATE THE DECLINE IN RENAL FUNCTION THAT ACCOMPANIES AGING. THESE PROCESSES MIGHT BE EXACERBATED BY PROGRAMMED CHANGES IN VASCULAR STRUCTURE AND FUNCTION, AND ALTERATIONS IN ENDOCRINE AND METABOLIC HOMEOSTASIS. PROGRAMMED EFFECTS MIGHT BE INITIATED AS EARLY AS THE PERICONCEPTUAL PHASE OF DEVELOPMENT, AND COULD INVOLVE EPIGENETIC CHANGES IN GENE EXPRESSION OR ALTERED STEM CELL ALLOCATION. BETTER UNDERSTANDING OF THESE PROCESSES COULD LEAD TO THE DEVELOPMENT OF NOVEL DIAGNOSTIC AND PREVENTIVE MEASURES, AND TO EARLY DETECTION OF AT-RISK INDIVIDUALS. BY MONITORING BLOOD PRESSURE, WEIGHT, AND RENAL FUNCTION IN CHILDREN, IT MIGHT BE POSSIBLE TO REDUCE THE RISK OF CARDIOVASCULAR AND RENAL DISEASE IN LATER LIFE. 2006 13 4983 27 PATHOPHYSIOLOGY, CELLULAR AND MOLECULAR MECHANISMS OF FOETAL GROWTH RETARDATION. IN MAMMALS, SIZE AT BIRTH IS THE OUTCOME OF LENGTH OF GESTATION AND RATE OF FOETAL GROWTH. IN THE ABSENCE OF PREMATURE DELIVERY, FOETAL SIZE WITHIN SPECIES IS DETERMINED PRINCIPALLY BY FOETAL GROWTH RATE WHICH IS DEPENDENT ON BOTH GENETIC AND EPIGENETIC FACTORS. FAILURE OF EITHER OF THESE MECHANISMS LEADS TO FOETAL GROWTH RETARDATION. IN MAMMALS, INCLUDING HUMAN INFANTS, FOETAL GROWTH RETARDATION CAN OCCUR NATURALLY OR PATHOLOGICALLY. ONE MAJOR CAUSE FOR NATURAL FOETAL GROWTH RETARDATION OR RUNTING IS THE INCREASE IN LITTER SIZE. IN MANY CASES, HOWEVER, THE CAUSE OF RUNTING IS UNKNOWN. PARENTAL GENOTYPE OR ANTIGENIC DIFFERENCES BETWEEN THE MOTHER AND THE DEVELOPING CONCEPTUS MAY BE POTENTIAL CAUSES. PATHOLOGICAL FOETAL GROWTH RETARDATION OR INTRAUTERINE GROWTH RETARDATION (IUGR) IS DUE TO GENETIC CAUSES (CHROMOSOMAL ABNORMALITIES OR INHERITED SYNDROMES) OR EPIGENETIC CAUSES (INTRAUTERINE INFECTIONS, TOXINS AND CHEMICALS, MATERNAL DISEASES OF PREGNANCY AFFECTING THE PLACENTA). THE UNDERLYING PATHOPHYSIOLOGICAL PROCESSES THAT OCCUR AT THE CELLULAR AND MOLECULAR LEVEL IN IUGR ARE STILL UNKNOWN. REDUCTION IN THE SUPPLY OF SUBSTRATES THAT ARE NECESSARY FOR NORMAL CELLULAR FUNCTION, AND ALTERATION IN MEDIATOR MOLECULES THAT REGULATE CELLULAR GROWTH AND DIFFERENTIATION, ARE IMPORTANT MECHANISMS. A DECREASE IN GROWTH PROMOTING FACTORS OR AN INCREASE IN GROWTH INHIBITORY FACTORS MAY LEAD TO GROWTH FAILURE. GROWTH FACTORS AND THEIR RECEPTORS ARE EXPRESSED IN THE DEVELOPING EMBRYO (AS EARLY AS THE 1-2-CELL STAGE), PLACENTA AND MATERNAL UTERINE TISSUES, SUGGESTING THAT THESE MOLECULES MAY PLAY A ROLE IN REGULATING NORMAL GROWTH AND DIFFERENTIATION OF THE CONCEPTUS AS WELL AS MATERNAL REPRODUCTIVE TISSUES. THE LOCAL EXPRESSION WITHIN DEVELOPING TISSUES INDICATES THAT THESE FACTORS ACT IN EITHER AUTOCRINE OR PARACRINE MECHANISM. RECENT STUDIES USING GENE TARGETING TO KNOCK OUT ONE ALLELE OF INSULIN-LIKE GROWTH FACTOR II (IGF II) GENE IN MICE WHICH RESULTED IN GROWTH RETARDED PUPS AT BIRTH, STRONGLY SUPPORT THE IMPORTANCE OF LOCAL IGF II IN REGULATING TISSUE GROWTH. FOETAL GROWTH RETARDATION HAS ALSO BEEN INDUCED EXPERIMENTALLY IN SEVERAL SPECIES USING ONE OF THE FOLLOWING METHODS: (I) MATERNAL UNDERNUTRITION, (II) CHRONIC HYPOXIA, (III) PROLONGED REDUCTION IN UTERINE BLOOD FLOW, (IV) REDUCTION IN PLACENTAL SIZE, AND (V) ENDOCRINE ALTERATIONS. THESE MODELS PROVIDE USEFUL INFORMATION ON THE PHYSIOLOGICAL MECHANISMS UNDERLYING A SPECIFIC TYPE OF GROWTH RETARDATION. THESE IN-VIVO MODELS AND IN-VIVO TISSUE CULTURE MODELS CAN NOW BE ANALYSED BY BIOCHEMICAL AND MOLECULAR BIOLOGICAL TECHNIQUES TO UNRAVEL THE BASIC MECHANISMS THAT UNDERLIE FOETAL GROWTH RETARDATION. 1993 14 6234 31 THE LONG-TERM EFFECTS OF PRENATAL DEVELOPMENT ON GROWTH AND METABOLISM. PEOPLE WHO WERE SMALL AT BIRTH AND HAD POOR INFANT GROWTH HAVE AN INCREASED RISK OF ADULT CARDIOVASCULAR DISEASE, OSTEOPOROSIS, AND TYPE 2 DIABETES, PARTICULARLY IF THEIR RESTRICTED EARLY GROWTH WAS FOLLOWED BY INCREASED CHILDHOOD WEIGHT GAIN. THESE RELATIONS EXTEND ACROSS THE NORMAL RANGE OF BIRTH SIZE IN A GRADED MANNER, SO REDUCED SIZE IS NOT A PREREQUISITE. IN ADDITION, LARGER BIRTH SIZE IS ASSOCIATED WITH RISKS OF OBESITY AND TYPE 2 DIABETES. THE ASSOCIATIONS APPEAR TO REFLECT DEVELOPMENTAL PLASTIC RESPONSES MADE BY THE FETUS AND INFANT BASED ON CUES ABOUT THE ENVIRONMENT, INFLUENCED BY MATERNAL CHARACTERISTICS INCLUDING DIET, BODY COMPOSITION, STRESS, AND EXERCISE LEVELS. THESE RESPONSES INVOLVE EPIGENETIC PROCESSES THAT MODIFY THE OFFSPRING'S PHENOTYPE. VULNERABILITY TO ILL HEALTH RESULTS IF THE ENVIRONMENT IN INFANCY, CHILDHOOD, AND LATER LIFE IS MISMATCHED TO THE PHENOTYPE INDUCED IN DEVELOPMENT, INFORMED BY THE DEVELOPMENTAL CUES. THIS MISMATCH MAY ARISE THROUGH UNBALANCED DIET OR BODY COMPOSITION OF THE MOTHER OR A CHANGE IN LIFESTYLE FACTORS BETWEEN GENERATIONS. THESE INSIGHTS OFFER NEW POSSIBILITIES FOR THE EARLY DIAGNOSIS AND PREVENTION OF CHRONIC DISEASE. 2011 15 2007 29 EPIGENETIC BASIS FOR FETAL ORIGINS OF AGE-RELATED DISEASE. THE CURRENT CONCEPT OF FETAL ORIGINS OF ADULT DISEASES DESCRIBES IN UTERO PROGRAMMING, OR ADAPTATION TO A SPECTRUM OF ADVERSE ENVIRONMENTAL CONDITIONS THAT ULTIMATELY LEADS TO INCREASED SUSCEPTIBILITY TO AGE-RELATED DISEASES (E.G., TYPE 2 DIABETES AND CARDIOVASCULAR DISEASE) LATER IN LIFE. ALTHOUGH THE PRECISE MECHANISM OF THIS BIOLOGICAL MEMORY REMAINS UNCLEAR, MOUNTING EVIDENCE SUGGESTS AN EPIGENETIC BASIS. THE INCREASED SUSCEPTIBILITY TO CHRONIC DISEASE AND INVOLVEMENT OF MULTIPLE ORGAN SYSTEMS THAT IS OBSERVED IS ANALOGOUS TO THE DECLINE IN RESISTANCE TO DISEASE THAT IS TYPICAL OF NORMAL AGING. ALTHOUGH THE CUMULATIVE ENVIRONMENT OVER THE COURSE OF A LIFETIME CAN INDUCE INCREASING EPIGENETIC DYSREGULATION, WE PROPOSE THAT ADVERSE EVENTS THAT OCCUR DURING EARLY DEVELOPMENT CAN INDUCE SIGNIFICANT ADDITIONAL DYSREGULATION OF THE EPIGENOME. HERE, WE DESCRIBE THE CURRENT EVIDENCE FOR FETAL ORIGINS OF ADULT DISEASE AND THE ASSOCIATED ROLE OF EPIGENETIC DYSREGULATION. IN ADDITION, WE PRESENT A NEW PERSPECTIVE ON THE INDUCTION OF EPIGENETIC ALTERATIONS IN UTERO, WHICH SUBSEQUENTLY LEAD TO AN AGING PHENOTYPE MARKED BY INCREASED SUSCEPTIBILITY TO AGE-RELATED DISEASES. 2010 16 3582 23 IMPACT OF PRENATAL AND EARLY LIFE ENVIRONMENTAL EXPOSURES ON NORMAL HUMAN DEVELOPMENT. THE GLOBAL BURDEN AND PATTERN OF DISEASE HAS CHANGED IN RECENT DECADES, WITH FEWER EARLY CHILDHOOD DEATHS AND LONGER LIVES COMPLICATED BY CHRONIC DISEASE. DISRUPTION OF NORMAL HUMAN GROWTH AND DEVELOPMENT BY ADVERSE ENVIRONMENTAL EXPOSURES, ESPECIALLY DURING FOETAL DEVELOPMENT AND EARLY POSTNATAL LIFE INCREASE LIFE-LONG RISK OF CHRONIC DISEASE. THE DEVELOPMENTAL TIMING AND METHOD OF ADVERSE EXPOSURE DETERMINES THE LIKELY IMPACT ON HEALTH AND DEVELOPMENT. WHILE MANY ORGAN SYSTEMS ARE STRUCTURALLY AND FUNCTIONALLY MATURE AT BIRTH, THE CNS, RESPIRATORY AND IMMUNE SYSTEMS ARE NOT AND UNDERGO PROLONGED PERIODS OF POSTNATAL GROWTH AND DEVELOPMENT. AS SUCH, THESE ORGAN SYSTEMS ARE VULNERABLE TO ADVERSE EFFECTS OF BOTH PRENATAL AND POSTNATAL ENVIRONMENTAL EXPOSURES. WHILE THE PRECISE MECHANISMS UNDERLYING CHRONIC DISEASE ARE UNKNOWN, EPIGENETIC MECHANISMS AND THE INDUCTION OF OXIDATIVE STRESS ARE LIKELY TO BE INVOLVED. AN UNDERSTANDING OF THESE PROCESSES IS NECESSARY TO DEVELOP MITIGATION STRATEGIES AIMED AT REDUCING CHRONIC DISEASE PREVALENCE. 2021 17 1801 32 EFFECT OF MATERNAL DIET ON THE EPIGENOME: IMPLICATIONS FOR HUMAN METABOLIC DISEASE. THE RAPID INCREASE IN THE INCIDENCE OF CHRONIC NON-COMMUNICABLE DISEASES OVER THE PAST TWO DECADES CANNOT BE EXPLAINED SOLELY BY GENETIC AND ADULT LIFESTYLE FACTORS. THERE IS NOW CONSIDERABLE EVIDENCE THAT THE FETAL AND EARLY POSTNATAL ENVIRONMENT ALSO STRONGLY INFLUENCES THE RISK OF DEVELOPING SUCH DISEASES IN LATER LIFE. HUMAN STUDIES HAVE SHOWN THAT LOW BIRTH WEIGHT IS ASSOCIATED WITH AN INCREASED RISK OF CVD, TYPE II DIABETES, OBESITY AND HYPERTENSION, ALTHOUGH RECENT STUDIES HAVE SHOWN THAT OVER-NUTRITION IN EARLY LIFE CAN ALSO INCREASE SUSCEPTIBILITY TO FUTURE METABOLIC DISEASE. THESE FINDINGS HAVE BEEN REPLICATED IN A VARIETY OF ANIMAL MODELS, WHICH HAVE SHOWN THAT BOTH MATERNAL UNDER- AND OVER-NUTRITION CAN INDUCE PERSISTENT CHANGES IN GENE EXPRESSION AND METABOLISM WITHIN THE OFFSPRING. THE MECHANISM BY WHICH THE MATERNAL NUTRITIONAL ENVIRONMENT INDUCES SUCH CHANGES IS BEGINNING TO BE UNDERSTOOD AND INVOLVES THE ALTERED EPIGENETIC REGULATION OF SPECIFIC GENES. THE DEMONSTRATION OF A ROLE FOR ALTERED EPIGENETIC REGULATION OF GENES IN THE DEVELOPMENTAL INDUCTION OF CHRONIC DISEASES RAISES THE POSSIBILITY THAT NUTRITIONAL OR PHARMACEUTICAL INTERVENTIONS MAY BE USED TO MODIFY LONG-TERM CARDIO-METABOLIC DISEASE RISK AND COMBAT THIS RAPID RISE IN CHRONIC NON-COMMUNICABLE DISEASES. 2011 18 6426 24 THE TRANSGENERATIONAL TRANSMISSION OF THE PATERNAL TYPE 2 DIABETES-INDUCED SUBFERTILITY PHENOTYPE. DIABETES IS A CHRONIC METABOLIC DISORDER CHARACTERIZED BY HYPERGLYCEMIA AND ASSOCIATED WITH MANY HEALTH COMPLICATIONS DUE TO THE LONG-TERM DAMAGE AND DYSFUNCTION OF VARIOUS ORGANS. A CONSEQUENTIAL COMPLICATION OF DIABETES IN MEN IS REPRODUCTIVE DYSFUNCTION, REDUCED FERTILITY, AND POOR REPRODUCTIVE OUTCOMES. HOWEVER, THE MOLECULAR MECHANISMS RESPONSIBLE FOR DIABETIC ENVIRONMENT-INDUCED SPERM DAMAGE AND OVERALL DECREASED REPRODUCTIVE OUTCOMES ARE NOT FULLY ESTABLISHED. WE EVALUATED THE EFFECTS OF TYPE 2 DIABETES EXPOSURE ON THE REPRODUCTIVE SYSTEM AND THE REPRODUCTIVE OUTCOMES OF MALES AND THEIR MALE OFFSPRING, USING A MOUSE MODEL. WE DEMONSTRATE THAT PATERNAL EXPOSURE TO TYPE 2 DIABETES MEDIATES INTERGENERATIONAL AND TRANSGENERATIONAL EFFECTS ON THE REPRODUCTIVE HEALTH OF THE OFFSPRING, ESPECIALLY ON SPERM QUALITY, AND ON METABOLIC CHARACTERISTICS. GIVEN THE TRANSGENERATIONAL IMPAIRMENT OF REPRODUCTIVE AND METABOLIC PARAMETERS THROUGH TWO GENERATIONS, THESE CHANGES LIKELY TAKE THE FORM OF INHERITED EPIGENETIC MARKS THROUGH THE GERMLINE. OUR RESULTS EMPHASIZE THE IMPORTANCE OF IMPROVING METABOLIC HEALTH NOT ONLY IN WOMEN OF REPRODUCTIVE AGE, BUT ALSO IN POTENTIAL FATHERS, IN ORDER TO REDUCE THE NEGATIVE IMPACTS OF DIABETES ON SUBSEQUENT GENERATIONS. 2021 19 3101 20 GENOMIC IMPRINTING: SENSING THE ENVIRONMENT AND DRIVING THE FETAL GROWTH. PURPOSE OF REVIEW: GENOMIC IMPRINTING IS AN EPIGENETICALLY-DRIVEN PHENOMENON THAT RESPONDS TO ENVIRONMENTAL STIMULI TO DETERMINE THE FETAL GROWTH TRAJECTORY. THIS REVIEW AIMS AT DESCRIBING THE TRANSGENERATIONAL MEANING OF GENOMIC IMPRINTING WHILE SUPPORTING THE STUDY OF GENOMIC IMPRINTING IN PLACENTA FOR THE DETERMINATION OF AN IMPORTANT BIOMARKER OF CHRONIC AND DEVELOPMENTAL DISORDERS IN CHILDREN AS DRIVEN BY THE ENVIRONMENT. RECENT FINDINGS: RECENT WORK HAS SHOWN THAT GENOMIC IMPRINTING REACHES BEYOND THE BASIC SIGNIFICANCE OF AN EPIGENETIC MARK REGULATING GENE EXPRESSION. GENOMIC IMPRINTING HAS BEEN THEORIZED AS THE MAIN DETERMINANT OF EPIGENETIC INHERITANCE. CONCOMITANTLY, NEW STUDIES IN THE FIELD OF MOLECULAR EPIDEMIOLOGY BECAME AVAILABLE THAT TIE THE FETAL GROWTH TRAJECTORY TO GENOMIC IMPRINTING IN RESPONSE TO ENVIRONMENTAL STIMULI, MAKING OF GENOMIC IMPRINTING THE DRIVING FORCE OF THE FETAL GROWTH. WHEN CARRIED OUT IN PLACENTA, THE EFFECTOR OF THE INTRAUTERINE ENVIRONMENT AS CONVEYED BY THE MATERNAL EXPOSURE TO THE GENERAL LIFE ENVIRONMENT, THE STUDY OF GENOMIC IMPRINTING MAY REVEAL CRITICAL INFORMATION ON ALTERATIONS OF THE FETAL GROWTH TRAJECTORY. SUMMARY: THE STUDY OF GENOMIC IMPRINTING PROFILES IN PLACENTAS FROM BIRTH COHORTS OF INDIVIDUALS EXPOSED TO DIFFERENT ENVIRONMENTAL STIMULI CAN PROVIDE A NEW, MUCH NEEDED, TOOL FOR THE ELABORATION OF EFFECTIVE PUBLIC HEALTH INTERVENTION PLANS FOR CHILD HEALTH. 2014 20 5202 30 PRENATAL ORIGINS OF ADULT DISEASE. PURPOSE OF REVIEW: HUMAN EPIDEMIOLOGICAL AND ANIMAL STUDIES SHOW THAT MANY CHRONIC ADULT CONDITIONS HAVE THEIR ANTECEDENTS IN COMPROMISED FETAL AND EARLY POSTNATAL DEVELOPMENT. DEVELOPMENTAL PROGRAMMING IS DEFINED AS THE RESPONSE BY THE DEVELOPING MAMMALIAN ORGANISM TO A SPECIFIC CHALLENGE DURING A CRITICAL TIME WINDOW THAT ALTERS THE TRAJECTORY OF DEVELOPMENT WITH RESULTING PERSISTENT EFFECTS ON PHENOTYPE. MAMMALS PASS MORE BIOLOGICAL MILESTONES BEFORE BIRTH THAN ANY OTHER TIME IN THEIR LIVES. EACH INDIVIDUAL'S PHENOTYPE IS INFLUENCED BY THE DEVELOPMENTAL ENVIRONMENT AS MUCH AS THEIR GENES. A BETTER UNDERSTANDING IS REQUIRED OF GENE-ENVIRONMENT INTERACTIONS LEADING TO ADULT DISEASE. RECENT FINDINGS: DURING DEVELOPMENT, THERE ARE CRITICAL PERIODS OF VULNERABILITY TO SUBOPTIMAL CONDITIONS WHEN PROGRAMMING MAY PERMANENTLY MODIFY DISEASE SUSCEPTIBILITY. PROGRAMMING INVOLVES STRUCTURAL CHANGES IN IMPORTANT ORGANS; ALTERED CELL NUMBER, IMBALANCE IN DISTRIBUTION OF DIFFERENT CELL TYPES WITHIN THE ORGAN, AND ALTERED BLOOD SUPPLY OR RECEPTOR NUMBERS. COMPENSATORY EFFORTS BY THE FETUS MAY CARRY A PRICE. EFFECTS OF PROGRAMMING MAY PASS ACROSS GENERATIONS BY MECHANISMS THAT DO NOT NECESSARILY INVOLVE STRUCTURAL GENE CHANGES. PROGRAMMING OFTEN HAS DIFFERENT EFFECTS IN MALES AND FEMALES. SUMMARY: DEVELOPMENTAL PROGRAMMING SHOWS THAT EPIGENETIC FACTORS PLAY MAJOR ROLES IN DEVELOPMENT OF PHENOTYPE AND PREDISPOSITION TO DISEASE IN LATER LIFE. 2008