1 3859 138 ISLET STRUCTURE AND FUNCTION IN THE GK RAT. TYPE 2 DIABETES MELLITUS (T2D) ARISES WHEN THE ENDOCRINE PANCREAS FAILS TO SECRETE SUFFICIENT INSULIN TO COPE WITH THE METABOLIC DEMAND BECAUSE OF BETA-CELL SECRETORY DYSFUNCTION AND/OR DECREASED BETA-CELL MASS. DEFINING THE NATURE OF THE PANCREATIC ISLET DEFECTS PRESENT IN T2D HAS BEEN DIFFICULT, IN PART BECAUSE HUMAN ISLETS ARE INACCESSIBLE FOR DIRECT STUDY. THIS REVIEW IS AIMED TO ILLUSTRATE TO WHAT EXTENT THE GOTO-KAKIZAKI RAT, ONE OF THE BEST CHARACTERIZED ANIMAL MODELS OF SPONTANEOUS T2D, HAS PROVED TO BE A VALUABLE TOOL OFFERING SUFFICIENT COMMONALITIES TO STUDY THIS ASPECT. A COMPREHENSIVE COMPENDIUM OF THE MULTIPLE FUNCTIONAL GK ISLET ABNORMALITIES SO FAR IDENTIFIED IS PROPOSED IN THIS PERSPECTIVE. THE PATHOGENESIS OF DEFECTIVE BETA-CELL NUMBER AND FUNCTION IN THE GK MODEL IS ALSO DISCUSSED. IT IS PROPOSED THAT THE DEVELOPMENT OF T2D IN THE GK MODEL RESULTS FROM THE COMPLEX INTERACTION OF MULTIPLE EVENTS: (I) SEVERAL SUSCEPTIBILITY LOCI CONTAINING GENES RESPONSIBLE FOR SOME DIABETIC TRAITS (DISTINCT LOCI ENCODING IMPAIRMENT OF BETA-CELL METABOLISM AND INSULIN EXOCYTOSIS, BUT NO QUANTITATIVE TRAIT LOCUS FOR DECREASED BETA-CELL MASS); (II) GESTATIONAL METABOLIC IMPAIRMENT INDUCING AN EPIGENETIC PROGRAMMING OF THE OFFSPRING PANCREAS (DECREASED BETA-CELL NEOGENESIS AND PROLIFERATION) TRANSMITTED OVER GENERATIONS; AND (III) LOSS OF BETA-CELL DIFFERENTIATION RELATED TO CHRONIC EXPOSURE TO HYPERGLYCAEMIA/HYPERLIPIDAEMIA, ISLET INFLAMMATION, ISLET OXIDATIVE STRESS, ISLET FIBROSIS AND PERTURBED ISLET VASCULATURE. 2010 2 6163 84 THE GK RAT BETA-CELL: A PROTOTYPE FOR THE DISEASED HUMAN BETA-CELL IN TYPE 2 DIABETES? INCREASING EVIDENCE INDICATES THAT DECREASED FUNCTIONAL BETA-CELL MASS IS THE HALLMARK OF TYPE 2 DIABETES (T2D) MELLITUS. NOWADAYS, THE DEBATE FOCUSES ON THE POSSIBLE MECHANISMS RESPONSIBLE FOR ABNORMAL ISLET MICROENVIRONMENT, DECREASED BETA-CELL NUMBER, IMPAIRED BETA-CELL FUNCTION, AND THEIR MULTIFACTORIAL AETIOLOGIES. THIS REVIEW IS AIMED TO ILLUSTRATE TO WHAT EXTEND THE GOTO-KAKIZAKI RAT, ONE OF THE BEST CHARACTERIZED ANIMAL MODELS OF SPONTANEOUS T2D, HAS PROVED BE A VALUABLE TOOL OFFERING SUFFICIENT COMMONALITIES TO STUDY THESE ASPECTS. WE PROPOSE THAT THE DEFECTIVE BETA-CELL MASS AND FUNCTION IN THE GK MODEL REFLECT THE COMPLEX INTERACTIONS OF MULTIPLE PATHOGENIC PLAYERS: (I) SEVERAL INDEPENDENT LOCI CONTAINING GENES RESPONSIBLE FOR SOME DIABETIC TRAITS (BUT NOT DECREASED BETA-CELL MASS); (II) GESTATIONAL METABOLIC IMPAIRMENT INDUCING AN EPIGENETIC PROGRAMMING OF THE PANCREAS (DECREASED BETA-CELL NEOGENESIS AND/OR PROLIFERATION) WHICH IS TRANSMITTED TO THE NEXT GENERATION; AND (III) LOSS OF BETA-CELL DIFFERENTIATION DUE TO CHRONIC EXPOSURE TO HYPERGLYCEMIA/HYPERLIPIDEMIA, INFLAMMATORY MEDIATORS, OXIDATIVE STRESS AND TO PERTURBED ISLET MICROARCHITECTURE. 2009 3 6164 115 THE GK RAT: A PROTOTYPE FOR THE STUDY OF NON-OVERWEIGHT TYPE 2 DIABETES. TYPE 2 DIABETES MELLITUS (T2D) ARISES WHEN THE ENDOCRINE PANCREAS FAILS TO SECRETE SUFFICIENT INSULIN TO COPE WITH THE METABOLIC DEMAND BECAUSE OF BETA-CELL SECRETORY DYSFUNCTION AND/OR DECREASED BETA-CELL MASS. DEFINING THE NATURE OF THE PANCREATIC ISLET DEFECTS PRESENT IN T2D HAS BEEN DIFFICULT, IN PART BECAUSE HUMAN ISLETS ARE INACCESSIBLE FOR DIRECT STUDY. THIS REVIEW IS AIMED TO ILLUSTRATE TO WHAT EXTENT THE GOTO KAKIZAKI RAT, ONE OF THE BEST CHARACTERIZED ANIMAL MODELS OF SPONTANEOUS T2D, HAS PROVED TO BE A VALUABLE TOOL OFFERING SUFFICIENT COMMONALITIES TO STUDY THIS ASPECT. A COMPREHENSIVE COMPENDIUM OF THE MULTIPLE FUNCTIONAL GK ABNORMALITIES SO FAR IDENTIFIED IS PROPOSED IN THIS PERSPECTIVE, TOGETHER WITH THEIR TIME-COURSE AND INTERACTIONS. A SPECIAL FOCUS IS GIVEN TOWARD THE PATHOGENESIS OF DEFECTIVE BETA-CELL NUMBER AND FUNCTION IN THE GK MODEL. IT IS PROPOSED THAT THE DEVELOPMENT OF T2D IN THE GK MODEL RESULTS FROM THE COMPLEX INTERACTION OF MULTIPLE EVENTS: (1) SEVERAL SUSCEPTIBILITY LOCI CONTAINING GENES RESPONSIBLE FOR SOME DIABETIC TRAITS; (2) GESTATIONAL METABOLIC IMPAIRMENT INDUCING AN EPIGENETIC PROGRAMMING OF THE OFFSPRING PANCREAS AND THE MAJOR INSULIN TARGET TISSUES; AND (3) ENVIRONMENTALLY INDUCED LOSS OF BETA-CELL DIFFERENTIATION DUE TO CHRONIC EXPOSURE TO HYPERGLYCEMIA/HYPERLIPIDEMIA, INFLAMMATION, AND OXIDATIVE STRESS. 2012 4 1302 65 DEFECTIVE FUNCTIONAL BETA-CELL MASS AND TYPE 2 DIABETES IN THE GOTO-KAKIZAKI RAT MODEL. INCREASING EVIDENCE INDICATES THAT DECREASED FUNCTIONAL BETA-CELL MASS IS THE HALLMARK OF TYPE 2 DIABETES MELLITUS. THEREFORE, THE DEBATE FOCUSES ON THE POSSIBLE MECHANISMS RESPONSIBLE FOR ABNORMAL ISLET MICROENVIRONMENT, DECREASED BETA-CELL NUMBER, IMPAIRED BETA-CELL FUNCTION AND THEIR MULTIFACTORIAL ETIOLOGIES. THE INFORMATION AVAILABLE ON THE GOTO-KAKIZAKI/PAR RAT LINE, ONE OF THE BEST CHARACTERIZED ANIMAL MODELS OF SPONTANEOUS TYPE 2 DIABETES MELLITUS, ARE REVIEWED IN SUCH A PERSPECTIVE. WE PROPOSE THAT THE DEFECTIVE BETA-CELL MASS AND FUNCTION IN THE GOTO-KAKIZAKI/PAR MODEL REFLECT THE COMPLEX INTERACTIONS OF MULTIPLE PATHOGENIC PLAYERS, INCLUDING SEVERAL INDEPENDENT LOCI CONTAINING GENES RESPONSIBLE FOR SOME DIABETIC TRAITS (BUT NOT DECREASED BETA-CELL MASS), GESTATIONAL METABOLIC IMPAIRMENT INDUCING AN EPIGENETIC PROGRAMMING OF THE PANCREAS (DECREASED BETA-CELL NEOGENESIS), WHICH IS TRANSMITTED TO THE NEXT GENERATION, AND LOSS OF BETA-CELL DIFFERENTIATION DUE TO CHRONIC EXPOSURE TO HYPERGLYCEMIA, INFLAMMATORY MEDIATORS, OXIDATIVE STRESS AND PERTURBED ISLET MICROARCHITECTURE. 2007 5 5250 64 PROGRAMMED DISORDERS OF BETA-CELL DEVELOPMENT AND FUNCTION AS ONE CAUSE FOR TYPE 2 DIABETES? THE GK RAT PARADIGM. NOW THAT THE REDUCTION IN BETA-MASS HAS BEEN CLEARLY ESTABLISHED IN HUMANS WITH TYPE 2 DIABETES MELLITUS (T2DM) 1-4, THE DEBATE FOCUSES ON THE POSSIBLE MECHANISMS RESPONSIBLE FOR DECREASED BETA-CELL NUMBER AND IMPAIRED BETA-CELL FUNCTION AND THEIR MULTIFACTORIAL ETIOLOGY. APPROPRIATE INBRED RODENT MODELS ARE ESSENTIAL TOOLS FOR IDENTIFICATION OF GENES AND ENVIRONMENTAL FACTORS THAT INCREASE THE RISK OF ABNORMAL BETA-CELL FUNCTION AND OF T2DM. THE INFORMATION AVAILABLE IN THE GOTO-KAKIZAKI (GK) RAT, ONE OF THE BEST CHARACTERIZED ANIMAL MODELS OF SPONTANEOUS T2DM, ARE REVIEWED IN SUCH A PERSPECTIVE. WE PROPOSE THAT THE DEFECTIVE BETA-CELL MASS AND FUNCTION IN THE GK MODEL REFLECT THE COMPLEX INTERACTIONS OF THREE PATHOGENIC PLAYERS: (1) SEVERAL INDEPENDENT LOCI CONTAINING GENES CAUSING IMPAIRED INSULIN SECRETION; (2) GESTATIONAL METABOLIC IMPAIRMENT INDUCING A PROGRAMMING OF ENDOCRINE PANCREAS (DECREASED BETA-CELL NEOGENESIS) WHICH IS TRANSMITTED TO THE NEXT GENERATION; AND (3) SECONDARY (ACQUIRED) LOSS OF BETA-CELL DIFFERENTIATION DUE TO CHRONIC EXPOSURE TO HYPERGLYCEMIA (GLUCOTOXICITY). AN IMPORTANT MESSAGE IS THAT THE 'HERITABLE' DETERMINANTS OF T2DM ARE NOT SIMPLY DEPENDANT ON GENETIC FACTORS, BUT PROBABLY INVOLVE TRANSGENERATIONAL EPIGENETIC RESPONSES. 2005 6 599 37 BETA-CELL DIFFERENTIATION STATUS IN TYPE 2 DIABETES. TYPE 2 DIABETES (T2D) AFFECTS 415 MILLION PEOPLE WORLDWIDE AND IS CHARACTERIZED BY CHRONIC HYPERGLYCAEMIA AND INSULIN RESISTANCE, PROGRESSING TO INSUFFICIENT INSULIN PRODUCTION, AS A RESULT OF BETA-CELL FAILURE. OVER TIME, CHRONIC HYPERGLYCAEMIA CAN ULTIMATELY LEAD TO LOSS OF BETA-CELL FUNCTION, LEAVING PATIENTS INSULIN-DEPENDENT. UNTIL RECENTLY THE LOSS OF BETA-CELL MASS SEEN IN T2D WAS CONSIDERED TO BE THE RESULT OF INCREASED RATES OF APOPTOSIS; HOWEVER, IT HAS BEEN PROPOSED THAT APOPTOSIS ALONE CANNOT ACCOUNT FOR THE EXTENT OF BETA-CELL MASS LOSS SEEN IN THE DISEASE, AND THAT A LOSS OF FUNCTION MAY ALSO OCCUR AS A RESULT OF CHANGES IN BETA-CELL DIFFERENTIATION STATUS. IN THE PRESENT REVIEW, WE CONSIDER CURRENT KNOWLEDGE OF DETERMINANTS OF BETA-CELL FATE IN THE CONTEXT OF UNDERSTANDING ITS RELEVANCE TO DISEASE PROCESS IN T2D, AND ALSO THE IMPACT OF A DIABETOGENIC ENVIRONMENT (HYPERGLYCAEMIA, HYPOXIA, INFLAMMATION AND DYSLIPIDAEMIA) ON THE EXPRESSION OF GENES INVOLVED IN MAINTENANCE OF BETA-CELL IDENTITY. WE DESCRIBE CURRENT KNOWLEDGE OF THE IMPACT OF THE DIABETIC MICROENVIRONMENT ON GENE REGULATORY PROCESSES SUCH ALTERNATIVE SPLICING, THE EXPRESSION OF DISALLOWED GENES AND EPIGENETIC MODIFICATIONS. ELUCIDATING THE MOLECULAR MECHANISMS THAT UNDERPIN CHANGES TO BETA-CELL DIFFERENTIATION STATUS AND THE CONCOMITANT BETA-CELL FAILURE OFFERS POTENTIAL TREATMENT TARGETS FOR THE FUTURE MANAGEMENT OF PATIENTS WITH T2D. 2016 7 4263 36 MICRO(RNA) MANAGEMENT AND MISMANAGEMENT OF THE ISLET. PANCREATIC BETA-CELLS LOCATED WITHIN THE ISLETS OF LANGERHANS PLAY A CENTRAL ROLE IN METABOLIC CONTROL. THE MAIN FUNCTION OF THESE CELLS IS TO PRODUCE AND SECRETE INSULIN IN RESPONSE TO A RISE IN CIRCULATING LEVELS OF GLUCOSE AND OTHER NUTRIENTS. THE RELEASE OF INSUFFICIENT INSULIN TO COVER THE ORGANISM NEEDS RESULTS IN CHRONIC HYPERGLYCEMIA AND DIABETES DEVELOPMENT. BETA-CELLS INSURE A HIGHLY SPECIALIZED TASK AND TO EFFICIENTLY ACCOMPLISH THEIR FUNCTION THEY NEED TO EXPRESS A SPECIFIC SET OF GENES. MICRORNAS (MIRNAS) ARE SMALL NONCODING RNAS AND KEY REGULATORS OF GENE EXPRESSION. INDEED, BY PARTIALLY PAIRING TO SPECIFIC SEQUENCES IN THE 3' UNTRANSLATED REGIONS OF TARGET MRNAS, EACH OF THEM CAN CONTROL THE TRANSLATION OF HUNDREDS OF TRANSCRIPTS. IN THIS REVIEW, WE FOCUS ON FEW KEY MIRNAS CONTROLLING ISLET FUNCTION AND DISCUSS: THEIR DIFFERENTIAL EXPRESSION IN TYPE 2 DIABETES (T2D), THEIR REGULATION BY GENETIC AND ENVIRONMENTAL FACTORS, AND THEIR THERAPEUTIC POTENTIAL. GENETIC AND EPIGENETIC CHANGES OR PROLONGED EXPOSURE TO HYPERGLYCEMIA AND/OR HYPERLIPIDEMIA CAN AFFECT THE BETA-CELL MIRNA EXPRESSION PROFILE, RESULTING IN IMPAIRED BETA-CELL FUNCTION AND SURVIVAL LEADING TO THE DEVELOPMENT OF T2D. EXPERIMENTAL APPROACHES PERMITTING TO CORRECT THE LEVEL OF MISEXPRESSED MIRNAS HAVE BEEN SHOWN TO PREVENT OR TREAT T2D IN ANIMAL MODELS, SUGGESTING THAT THESE SMALL RNAS MAY BECOME INTERESTING THERAPEUTIC TARGETS. HOWEVER, TRANSLATION OF THESE EXPERIMENTAL FINDINGS TO THE CLINICS WILL NECESSITATE THE DEVELOPMENT OF INNOVATIVE STRATEGIES ALLOWING SAFE AND SPECIFIC DELIVERY OF COMPOUNDS MODULATING THE LEVEL OF THE RELEVANT MIRNAS TO THE BETA-CELLS. 2020 8 3863 32 IT'S WHAT AND WHEN YOU EAT: AN OVERVIEW OF TRANSCRIPTIONAL AND EPIGENETIC RESPONSES TO DIETARY PERTURBATIONS IN PANCREATIC ISLETS. OUR EVER-CHANGING MODERN ENVIRONMENT IS A SIGNIFICANT CONTRIBUTOR TO THE INCREASED PREVALENCE OF MANY CHRONIC DISEASES, AND PARTICULARLY, TYPE 2 DIABETES MELLITUS (T2DM). ALTHOUGH THE MODERN ERA HAS USHERED IN NUMEROUS CHANGES TO OUR DAILY LIVING CONDITIONS, CHANGES IN "WHAT" AND "WHEN" WE EAT APPEAR TO DISPROPORTIONATELY FUEL THE RISE OF T2DM. THE PANCREATIC ISLET IS A KEY BIOLOGICAL CONTROLLER OF AN ORGANISM'S GLUCOSE HOMEOSTASIS AND THUS PLAYS AN OUTSIZED ROLE TO COORDINATE THE RESPONSE TO ENVIRONMENTAL FACTORS TO PRESERVE EUGLYCEMIA THROUGH A DELICATE BALANCE OF ENDOCRINE OUTPUTS. BOTH SUCCESSFUL AND FAILED ADAPTATION TO DYNAMIC ENVIRONMENTAL STIMULI HAS BEEN POSTULATED TO OCCUR DUE TO CHANGES IN THE TRANSCRIPTIONAL AND EPIGENETIC REGULATION OF PATHWAYS ASSOCIATED WITH ISLET SECRETORY FUNCTION AND SURVIVAL. THEREFORE, IN THIS REVIEW WE EXAMINED AND EVALUATED THE CURRENT EVIDENCE ELUCIDATING THE KEY EPIGENETIC MECHANISMS AND TRANSCRIPTIONAL PROGRAMS UNDERLYING THE ISLET'S COORDINATED RESPONSE TO THE INTERACTION BETWEEN THE TIMING AND THE COMPOSITION OF DIETARY NUTRIENTS COMMON TO MODERN LIFESTYLES. WITH THE EXPLOSION OF NEXT GENERATION SEQUENCING, ALONG WITH THE DEVELOPMENT OF NOVEL INFORMATIC AND -OMIC APPROACHES, FUTURE WORK WILL CONTINUE TO UNRAVEL THE ENVIRONMENTAL-EPIGENETIC RELATIONSHIP IN ISLET BIOLOGY WITH THE GOAL OF IDENTIFYING TRANSCRIPTIONAL AND EPIGENETIC TARGETS ASSOCIATED WITH ISLET PERTURBATIONS IN T2DM. 2022 9 2178 28 EPIGENETIC MECHANISMS OF MACROPHAGE ACTIVATION IN TYPE 2 DIABETES. THE ALARMING RISE OF OBESITY AND TYPE 2 DIABETES (T2D) HAS PUT A TREMENDOUS STRAIN ON GLOBAL HEALTHCARE SYSTEMS. OVER THE PAST DECADE EXTENSIVE RESEARCH HAS FOCUSED ON THE ROLE OF MACROPHAGES AS KEY MEDIATORS OF INFLAMMATION IN T2D. THE INFLAMMATORY ENVIRONMENT IN THE OBESE ADIPOSE TISSUE AND PANCREATIC BETA-CELL ISLETS CREATES AND PERPETUATES IMBALANCED INFLAMMATORY MACROPHAGE ACTIVATION. CONSEQUENCES OF THIS CHRONIC LOW-GRADE INFLAMMATION INCLUDE INSULIN RESISTANCE IN THE ADIPOSE TISSUE AND PANCREATIC BETA-CELL DYSFUNCTION. RECENTLY, THE EMERGING FIELD OF EPIGENETICS HAS PROVIDED NEW INSIGHTS INTO THE PATHOGENESIS OF T2D, WHILE ALSO AFFORDING POTENTIAL NEW OPPORTUNITIES FOR TREATMENT. IN MACROPHAGES, EPIGENETIC MECHANISMS ARE INCREASINGLY BEING RECOGNIZED AS CRUCIAL CONTROLLERS OF THEIR PHENOTYPE. HERE, WE FIRST DESCRIBE THE ROLE OF MACROPHAGES IN T2D. THEN WE ELABORATE ON EPIGENETIC MECHANISMS THAT REGULATE MACROPHAGE ACTIVATION, THEREBY FOCUSING ON T2D. NEXT, WE HIGHLIGHT HOW DIABETIC CONDITIONS SUCH AS HYPERLIPIDEMIA AND HYPERGLYCEMIA COULD INDUCE EPIGENETIC CHANGES THAT PROMOTE AN INFLAMMATORY MACROPHAGE PHENOTYPE. IN CONCLUSION WE DISCUSS POSSIBLE THERAPEUTIC INTERVENTIONS BY TARGETING MACROPHAGE EPIGENETICS AND SPECULATE ON FUTURE RESEARCH DIRECTIONS. 2017 10 1974 41 EPIGENETIC ALTERATIONS CAUSED BY NUTRITIONAL STRESS DURING FETAL PROGRAMMING OF THE ENDOCRINE PANCREAS. NUTRITION DURING CRITICAL PERIODS OF DEVELOPMENT IS ONE OF THE PIVOTAL FACTORS IN ESTABLISHING A LIFELONG HEALTHY METABOLISM. DIFFERENT NUTRITIONAL DEFICIENCIES SUCH AS A LOW AVAILABILITY OF PROTEINS IN THE MATERNAL DIET PRODUCE ALTERATIONS IN OFFSPRING THAT INCLUDE CHANGES IN INSULIN AND GLUCOSE METABOLISM, A DECREASE IN THE SIZE AND NUMBER OF CELLS OF PANCREATIC ISLETS OF LANGERHANS, AND PREMATURE AGEING OF THE SECRETORY FUNCTION OF PANCREATIC BETA CELLS. MOREOVER, IT HAS BEEN REPORTED THAT CHRONIC NUTRITIONAL STRESS IS ASSOCIATED WITH EPIGENETIC ALTERATIONS IN MECHANISMS OF GENE REGULATION DURING PANCREATIC DEVELOPMENT AND FUNCTION. THESE ALTERATIONS CAN LEAD TO DYSFUNCTIONAL STATES IN PANCREATIC BETA CELLS, WHICH IN THE LONG RUN ARE RESPONSIBLE FOR THE ONSET OF METABOLIC DISEASES LIKE TYPE 2 DIABETES. THE PRESENT REVIEW SUMMARIZES THE MOST IMPORTANT EVIDENCE IN RELATION TO THE PARTICIPATION OF EPIGENETIC MECHANISMS IN THE REGULATION OF GENE EXPRESSION DURING THE INTRAUTERINE PROGRAMMING OF THE ENDOCRINE PANCREAS IN ANIMAL MODELS. SUCH MECHANISMS INCLUDE DNA METHYLATION AS WELL AS MODIFICATIONS OF HISTONES AND MICRORNAS (MIRNAS). 2015 11 6335 30 THE ROLE OF DNA METHYLATION IN THE PATHOGENESIS OF TYPE 2 DIABETES MELLITUS. DIABETES MELLITUS (DM) IS A CHRONIC CONDITION CHARACTERISED BY BETA CELL DYSFUNCTION AND PERSISTENT HYPERGLYCAEMIA. THE DISORDER CAN BE DUE TO THE ABSENCE OF ADEQUATE PANCREATIC INSULIN PRODUCTION OR A WEAK CELLULAR RESPONSE TO INSULIN SIGNALLING. AMONG THE THREE TYPES OF DM, NAMELY, TYPE 1 DM (T1DM), TYPE 2 DM (T2DM), AND GESTATIONAL DM (GDM); T2DM ACCOUNTS FOR ALMOST 90% OF DIABETES CASES WORLDWIDE.EPIGENETIC TRAITS ARE STABLY HERITABLE PHENOTYPES THAT RESULT FROM CERTAIN CHANGES THAT AFFECT GENE FUNCTION WITHOUT ALTERING THE GENE SEQUENCE. WHILE EPIGENETIC TRAITS ARE CONSIDERED REVERSIBLE MODIFICATIONS, THEY CAN BE INHERITED MITOTICALLY AND MEIOTICALLY. IN ADDITION, EPIGENETIC TRAITS CAN RANDOMLY ARISE IN RESPONSE TO ENVIRONMENTAL FACTORS OR CERTAIN GENETIC MUTATIONS OR LESIONS, SUCH AS THOSE AFFECTING THE ENZYMES THAT CATALYSE THE EPIGENETIC MODIFICATION. IN THIS REVIEW, WE FOCUS ON THE ROLE OF DNA METHYLATION, A TYPE OF EPIGENETIC MODIFICATION, IN THE PATHOGENESIS OF T2DM. 2020 12 4185 30 METABOLIC ADAPTIONS/REPROGRAMMING IN ISLET BETA-CELLS IN RESPONSE TO PHYSIOLOGICAL STIMULATORS-WHAT ARE THE CONSEQUENCES. IRREVERSIBLE PANCREATIC BETA-CELL DAMAGE MAY BE A RESULT OF CHRONIC EXPOSURE TO SUPRAPHYSIOLOGICAL GLUCOSE OR LIPID CONCENTRATIONS OR CHRONIC EXPOSURE TO THERAPEUTIC ANTI-DIABETIC DRUGS. THE BETA-CELLS ARE ABLE TO RESPOND TO BLOOD GLUCOSE IN A NARROW CONCENTRATION RANGE AND RELEASE INSULIN IN RESPONSE, FOLLOWING ACTIVATION OF METABOLIC PATHWAYS SUCH AS GLYCOLYSIS AND THE TCA CYCLE. THE BETA-CELL CANNOT PROTECT ITSELF FROM GLUCOSE TOXICITY BY BLOCKING GLUCOSE UPTAKE, BUT INDEED RELIES ON ALTERNATIVE METABOLIC PROTECTION MECHANISMS TO AVOID DYSFUNCTION AND DEATH. ALTERATION OF NORMAL METABOLIC PATHWAY FUNCTION OCCURS AS A COUNTER REGULATORY RESPONSE TO HIGH NUTRIENT, INFLAMMATORY FACTOR, HORMONE OR THERAPEUTIC DRUG CONCENTRATIONS. METABOLIC REPROGRAMMING IS A TERM WIDELY USED TO DESCRIBE A CHANGE IN REGULATION OF VARIOUS METABOLIC ENZYMES AND TRANSPORTERS, USUALLY ASSOCIATED WITH CELL GROWTH AND PROLIFERATION AND MAY INVOLVE RESHAPING EPIGENETIC RESPONSES, IN PARTICULAR THE ACETYLATION AND METHYLATION OF HISTONE PROTEINS AND DNA. OTHER METABOLIC MODIFICATIONS SUCH AS MALONYLATION, SUCCINYLATION, HYDROXYBUTYRYLATION, ADP-RIBOSYLATION, AND LACTYLATION, MAY IMPACT REGULATORY PROCESSES, MANY OF WHICH NEED TO BE INVESTIGATED IN DETAIL TO CONTRIBUTE TO CURRENT ADVANCES IN METABOLISM. BY DESCRIBING MULTIPLE MECHANISMS OF METABOLIC ADAPTION THAT ARE AVAILABLE TO THE BETA-CELL ACROSS ITS LIFESPAN, WE HOPE TO IDENTIFY SITES FOR METABOLIC REPROGRAMMING MECHANISMS, MOST OF WHICH ARE INCOMPLETELY DESCRIBED OR UNDERSTOOD. MANY OF THESE MECHANISMS ARE RELATED TO PROMINENT ANTIOXIDANT RESPONSES. HERE, WE HAVE ATTEMPTED TO DESCRIBE THE KEY BETA-CELL METABOLIC ADAPTIONS AND CHANGES WHICH ARE REQUIRED FOR SURVIVAL AND FUNCTION IN VARIOUS PHYSIOLOGICAL, PATHOLOGICAL AND PHARMACOLOGICAL CONDITIONS. 2022 13 2964 28 GENETIC AND EPIGENETIC MECHANISMS UNDERLYING ARSENIC-ASSOCIATED DIABETES MELLITUS: A PERSPECTIVE OF THE CURRENT EVIDENCE. CHRONIC EXPOSURE TO ARSENIC HAS BEEN ASSOCIATED WITH THE DEVELOPMENT OF DIABETES MELLITUS (DM), A DISEASE CHARACTERIZED BY HYPERGLYCEMIA RESULTING FROM DYSREGULATION OF GLUCOSE HOMEOSTASIS. THIS REVIEW SUMMARIZES FOUR MAJOR MECHANISMS BY WHICH ARSENIC INDUCES DIABETES, NAMELY INHIBITION OF INSULIN-DEPENDENT GLUCOSE UPTAKE, PANCREATIC BETA-CELL DAMAGE, PANCREATIC BETA-CELL DYSFUNCTION AND STIMULATION OF LIVER GLUCONEOGENESIS THAT ARE SUPPORTED BY BOTH IN VIVO AND IN VITRO STUDIES. ADDITIONALLY, THE ROLE OF POLYMORPHIC VARIANTS ASSOCIATED WITH ARSENIC TOXICITY AND DISEASE SUSCEPTIBILITY, AS WELL AS EPIGENETIC MODIFICATIONS ASSOCIATED WITH ARSENIC EXPOSURE, ARE CONSIDERED IN THE CONTEXT OF ARSENIC-ASSOCIATED DM. TAKEN TOGETHER, IN VITRO, IN VIVO AND HUMAN GENETIC/EPIGENETIC STUDIES SUPPORT THAT ARSENIC HAS THE POTENTIAL TO INDUCE DM PHENOTYPES AND IMPAIR KEY PATHWAYS INVOLVED IN THE REGULATION OF GLUCOSE HOMEOSTASIS. 2017 14 4891 35 OXIDATIVE STRESS AND INFLAMMATORY MARKERS IN PREDIABETES AND DIABETES. PREDIABETES IS A STATE OF ELEVATED PLASMA GLUCOSE IN WHICH THE THRESHOLD FOR DIABETES HAS NOT YET BEEN REACHED AND CAN PREDISPOSE TO THE DEVELOPMENT OF TYPE 2 DIABETES AND CARDIOVASCULAR DISEASES. INSULIN RESISTANCE AND IMPAIRED BETA-CELL FUNCTION ARE OFTEN ALREADY PRESENT IN PREDIABETES. HYPERGLYCEMIA CAN UPREGULATE MARKERS OF CHRONIC INFLAMMATION AND CONTRIBUTE TO INCREASED REACTIVE OXYGEN SPECIES (ROS) GENERATION, WHICH ULTIMATELY CAUSE VASCULAR DYSFUNCTION. CONVERSELY, INCREASED OXIDATIVE STRESS AND INFLAMMATION CAN LEAD TO INSULIN RESISTANCE AND IMPAIRED INSULIN SECRETION. PROPER TREATMENT OF HYPERGLYCEMIA AND INHIBITION OF ROS OVERPRODUCTION IS CRUCIAL FOR DELAYING ONSET OF DIABETES AND FOR PREVENTION OF CARDIOVASCULAR COMPLICATIONS. THUS, IT IS IMPERATIVE TO DETERMINE THE MECHANISMS INVOLVED IN THE PROGRESSION FROM PREDIABETES TO DIABETES INCLUDING A CLARIFICATION OF HOW OLD AND NEW MEDICATIONS AFFECT OXIDATIVE AND IMMUNE MECHANISMS OF DIABETES. IN THIS REVIEW, WE DISCUSS THE RELATIONSHIP BETWEEN OXIDATIVE STRESS AND HYPERGLYCEMIA ALONG WITH LINKS BETWEEN INFLAMMATION AND PREDIABETES. ADDITIONALLY, THE EFFECTS OF HYPERGLYCEMIC MEMORY, MICROVESICLES, MICRO-RNA, AND EPIGENETIC REGULATION ON INFLAMMATION, OXIDATIVE STATE, AND GLYCEMIC CONTROL ARE HIGHLIGHTED. ADIPOSE TISSUE AND THEIR INFLUENCE ON CHRONIC INFLAMMATION ARE ALSO BRIEFLY REVIEWED. FINALLY, THE ROLE OF IMMUNE-TARGETED THERAPIES AND ANTI-DIABETIC MEDICATION ON GLYCEMIC CONTROL AND OXIDATIVE STRESS ARE DISCUSSED. 2019 15 776 31 CELL- AND TISSUE-SPECIFIC EPIGENETIC CHANGES ASSOCIATED WITH CHRONIC INFLAMMATION IN INSULIN RESISTANCE AND TYPE 2 DIABETES MELLITUS. TYPE 2 DIABETES MELLITUS (T2DM) IS A CHRONIC METABOLIC DISORDER CHARACTERIZED BY HYPERGLYCAEMIA, WHICH CAN CAUSE MICRO- AND MACROVASCULAR COMPLICATIONS. CHRONIC INFLAMMATION MAY BE THE CAUSE AND RESULT OF T2DM, AND ITS RELATED COMPLICATIONS AS AN IMBALANCE BETWEEN PRO- AND ANTI-INFLAMMATORY CYTOKINES CAN AFFECT IMMUNE FUNCTIONS. APART FROM GENETIC CHANGES OCCURRING WITHIN THE BODY RESULTING IN INFLAMMATION IN T2DM, EPIGENETIC MODIFICATIONS CAN MODIFY GENE EXPRESSION IN RESPONSE TO ENVIRONMENTAL CUES SUCH AS AN UNHEALTHY DIET, LACK OF EXERCISE AND OBESITY. THE MOST WIDELY STUDIED EPIGENETIC MODIFICATION, DNA METHYLATION (DNAM), REGULATES GENE EXPRESSION AND MAY MANIPULATE INFLAMMATORY GENES TO INCREASE OR DECREASE INFLAMMATION ASSOCIATED WITH T2DM. THIS REVIEW EXPLORES THE STUDIES RELATED TO EPIGENETIC CHANGES, MORE SPECIFICALLY DNAM, ASSOCIATED WITH CHRONIC INFLAMMATION IN T2DM, AT BOTH THE CELL AND TISSUE LEVELS. STUDYING EPIGENETIC ALTERATIONS DURING INFLAMMATORY RESPONSE, AS A RESULT OF GENETIC AND ENVIRONMENTAL SIGNALS, CREATES OPPORTUNITIES FOR THE DEVELOPMENT OF "EARLY DETECTION/RELATIVE RISK" TESTS TO AID IN PREVENTION OF T2DM. UNDERSTANDING INFLAMMATION IN T2DM AT THE GENE LEVEL IN INFLAMMATION-ASSOCIATED CELLS AND TISSUES MAY PROVIDE FURTHER INSIGHT FOR THE DEVELOPMENT OF SPECIFIC THERAPEUTIC TARGETS FOR THE DISORDER. 2018 16 426 33 ANTI-DIABETIC FUNCTIONS OF SOY ISOFLAVONE GENISTEIN: MECHANISMS UNDERLYING ITS EFFECTS ON PANCREATIC BETA-CELL FUNCTION. TYPE 2 DIABETES IS A RESULT OF CHRONIC INSULIN RESISTANCE AND LOSS OF FUNCTIONAL PANCREATIC BETA-CELL MASS. STRATEGIES TO PRESERVE BETA-CELL MASS AND A GREATER UNDERSTANDING OF THE MECHANISMS UNDERLYING BETA-CELL TURNOVER ARE NEEDED TO PREVENT AND TREAT THIS DEVASTATING DISEASE. GENISTEIN, A NATURALLY OCCURRING SOY ISOFLAVONE, IS REPORTED TO HAVE NUMEROUS HEALTH BENEFITS ATTRIBUTED TO MULTIPLE BIOLOGICAL FUNCTIONS. OVER THE PAST 10 YEARS, NUMEROUS STUDIES HAVE DEMONSTRATED THAT GENISTEIN HAS ANTI-DIABETIC EFFECTS, IN PARTICULAR, DIRECT EFFECTS ON BETA-CELL PROLIFERATION, GLUCOSE-STIMULATED INSULIN SECRETION AND PROTECTION AGAINST APOPTOSIS, INDEPENDENT OF ITS FUNCTIONS AS AN ESTROGEN RECEPTOR AGONIST, ANTIOXIDANT, OR TYROSINE KINASE INHIBITOR. EFFECTS ARE STRUCTURE-SPECIFIC AND NOT COMMON TO ALL FLAVONOIDS. WHILE THERE ARE LIMITED DATA ON THE EFFECTS OF GENISTEIN CONSUMPTION IN HUMANS WITH DIABETES, THERE ARE A PLETHORA OF ANIMAL AND CELL-CULTURE STUDIES THAT DEMONSTRATE A DIRECT EFFECT OF GENISTEIN ON BETA-CELLS AT PHYSIOLOGICALLY RELEVANT CONCENTRATIONS (<10 MUM). THE EFFECTS APPEAR TO INVOLVE CAMP/PKA SIGNALING AND THERE ARE SOME STUDIES THAT SUGGEST AN EFFECT ON EPIGENETIC REGULATION OF GENE EXPRESSION. THIS REVIEW FOCUSES ON THE ANTI-DIABETIC EFFECTS OF GENISTEIN IN BOTH IN VITRO AND IN VIVO MODELS AND POTENTIAL MECHANISMS UNDERLYING ITS DIRECT EFFECTS ON BETA-CELLS. 2013 17 1933 32 ENVIRONMENTAL FACTORS ASSOCIATED WITH TYPE 1 DIABETES. TYPE 1 DIABETES (T1D) IS A CHRONIC AUTOIMMUNE DISORDER THAT LEADS TO PROGRESSIVE PANCREATIC SS-CELL DESTRUCTION AND CULMINATES IN ABSOLUTE INSULIN DEFICIENCY AND STABLE HYPERGLYCAEMIA. IT IS VERY LIKELY THAT ENVIRONMENTAL FACTORS PLAY A ROLE IN TRIGGERING ISLET AUTOIMMUNITY. KNOWING WHETHER THEY HAVE TRUE RELEVANCE IN FAVORING T1D DEVELOPMENT IS ESSENTIAL FOR THE EFFECTIVE PREVENTION OF THE DISEASE. MOREOVER, PREVENTION COULD BE OBTAINED DIRECTLY INTERFERING WITH THE DEVELOPMENT OF AUTOIMMUNITY THROUGH AUTOANTIGEN-BASED IMMUNOTHERAPY. IN THIS NARRATIVE REVIEW, THE PRESENT POSSIBILITIES FOR THE PREVENTION OF T1D ARE DISCUSSED. PRESENTLY, INTERVENTIONS TO PREVENT T1D ARE GENERALLY MADE IN SUBJECTS IN WHOM AUTOIMMUNITY IS ALREADY ACTIVATED AND AUTOANTIBODIES AGAINST PANCREATIC CELL COMPONENTS HAVE BEEN DETECTED. PRACTICALLY, THE GOAL IS TO SLOW DOWN THE IMMUNE PROCESS BY PRESERVING THE NORMAL STRUCTURE OF THE PANCREATIC ISLETS FOR AS LONG AS POSSIBLE. UNFORTUNATELY, PRESENTLY METHODS ABLE TO AVOID THE RISK OF AUTOIMMUNE ACTIVATION ARE NOT AVAILABLE. ELIMINATION OF ENVIRONMENTAL FACTORS ASSOCIATED WITH T1D DEVELOPMENT, REVERSE OF EPIGENETIC MODIFICATIONS THAT FAVOR INITIATION OF AUTOIMMUNITY IN SUBJECTS EXPOSED TO ENVIRONMENTAL FACTORS AND USE OF AUTOANTIGEN-BASED IMMUNOTHERAPY ARE POSSIBLE APPROACHES, ALTHOUGH FOR ALL THESE MEASURES DEFINITIVE CONCLUSIONS CANNOT BE DRAWN. HOWEVER, THE ROAD IS TRACED AND IT IS POSSIBLE THAT IN A NOT SO DISTANT FUTURE AN EFFECTIVE PREVENTION OF THE DISEASE TO ALL THE SUBJECTS AT RISK CAN BE OFFERED. 2019 18 2549 27 EPIGENETICS IN OBESITY AND DIABETES MELLITUS: NEW INSIGHTS. A LONG-TERM COMPLICATION OF OBESITY IS THE DEVELOPMENT OF TYPE 2 DIABETES (T2D). PATIENTS WITH T2D HAVE BEEN DESCRIBED AS HAVING EPIGENETIC MODIFICATIONS. EPIGENETICS IS THE POST-TRANSCRIPTIONAL MODIFICATION OF DNA OR ASSOCIATED FACTORS CONTAINING GENETIC INFORMATION. THESE ENVIRONMENTALLY-INFLUENCED MODIFICATIONS, MAINTAINED DURING CELL DIVISION, CAUSE STABLE CHANGES IN GENE EXPRESSION. EPIGENETIC MODIFICATIONS OF T2D ARE DNA METHYLATION, ACETYLATION, UBIQUITYLATION, SUMOYLATION, AND PHOSPHORYLATION AT THE LYSINE RESIDUE AT THE AMINO TERMINUS OF HISTONES, AFFECTING DNA, HISTONES, AND NON-CODING RNA. DNA METHYLATION HAS BEEN SHOWN IN PANCREATIC ISLETS, ADIPOSE TISSUE, SKELETAL MUSCLE, AND THE LIVER. FURTHERMORE, EPIGENETIC CHANGES HAVE BEEN OBSERVED IN CHRONIC COMPLICATIONS OF T2D, SUCH AS DIABETIC NEPHROPATHY, DIABETIC RETINOPATHY, AND DIABETIC NEUROPATHY. RECENTLY, A NEW DRUG HAS BEEN DEVELOPED WHICH ACTS ON BROMODOMAINS AND EXTRATERMINAL (BET) DOMAIN PROTEINS, WHICH OPERATE LIKE EPIGENETIC READERS AND COMMUNICATE WITH CHROMATIN TO MAKE DNA ACCESSIBLE FOR TRANSCRIPTION BY INHIBITING THEM. THIS DRUG (APABETALONE) IS BEING STUDIED TO PREVENT MAJOR ADVERSE CARDIOVASCULAR EVENTS IN PEOPLE WITH T2D, LOW HDL CHOLESTEROL, CHRONIC KIDNEY FAILURE, AND RECENT CORONARY EVENTS. THIS REVIEW AIMS TO DESCRIBE THE RELATIONSHIP BETWEEN OBESITY, LONG-TERM COMPLICATIONS SUCH AS T2D, AND EPIGENETIC MODIFICATIONS AND THEIR POSSIBLE TREATMENTS. 2023 19 1451 26 DISALLOWED AND ALLOWED GENE EXPRESSION: TWO FACES OF MATURE ISLET BETA CELLS. GLUCOSE HOMEOSTASIS GREATLY DEPENDS ON THE MATCH BETWEEN FLUCTUATING INSULIN DEMANDS AND ADJUSTED RATES OF INSULIN SECRETION, WHICH IS THE FUNCTION OF PANCREATIC BETA CELLS. EMERGING EVIDENCE SUGGESTS THAT WHEN NEONATAL BETA CELLS MATURE, THEY ACQUIRE TWO FACES OF DIFFERENTIATED FUNCTION: AN EXPECTED "VISIBLE FACE" THAT DEPENDS ON SPECIFIC BETA CELL PROTEINS NEEDED FOR REGULATED INSULIN RELEASE, BUT ALSO A "HIDDEN FACE" THAT REPRESSES UBIQUITOUS PROTEINS TO PREVENT INAPPROPRIATE BETA CELL FUNCTION SUCH AS ELEVATED BASAL HORMONE SECRETION OR INSULIN RELEASE TRIGGERED BY EXERCISE. THIS REVIEW HIGHLIGHTS THIS NOVEL CONCEPT, AND WE FIRST PROPOSE THAT HIDDEN FACES MAY ALSO BE RELEVANT FOR OTHER SPECIALIZED TISSUE FUNCTIONS, SUCH AS KETOGENESIS IN THE LIVER. NEXT, WE DISCUSS THREE SCENARIOS IN WHICH ABERRANT GENE EXPRESSION CAUSES ABNORMAL GLUCOSE-INDUCED INSULIN RELEASE AND THE EPIGENETIC REGULATION OF THE HIDDEN FACE IN BETA CELLS. WE CONCLUDE WITH PERSPECTIVES FOR NEW RESEARCH, INCLUDING BETA CELL REPLACEMENT TO CURE DIABETES. 2016 20 3748 36 INSIGHTS INTO THE ROLE OF DNA METHYLATION AND PROTEIN MISFOLDING IN DIABETES MELLITUS. BACKGROUND: DIABETES MELLITUS IS A METABOLIC DISORDER THAT IS CHARACTERIZED BY IMPAIRED GLUCOSE TOLERANCE RESULTING FROM DEFECTS IN INSULIN SECRETION, INSULIN ACTION, OR BOTH. EPIGENETIC MODIFICATIONS, WHICH ARE DEFINED AS INHERITED CHANGES IN GENE EXPRESSION THAT OCCUR WITHOUT CHANGES IN GENE SEQUENCE, ARE INVOLVED IN THE ETIOLOGY OF DIABETES. METHODS: IN THIS REVIEW, WE FOCUSED ON THE ROLE OF DNA METHYLATION AND PROTEIN MISFOLDING AND THEIR CONTRIBUTION TO THE DEVELOPMENT OF BOTH TYPE 1 AND TYPE 2 DIABETES MELLITUS. RESULTS: CHANGES IN DNA METHYLATION IN PARTICULAR ARE HIGHLY ASSOCIATED WITH THE DEVELOPMENT OF DIABETES. PROTEIN FUNCTION IS DEPENDENT ON THEIR PROPER FOLDING IN THE ENDOPLASMIC RETICULUM. DEFECTIVE PROTEIN FOLDING AND CONSEQUENTLY THEIR FUNCTIONS HAVE ALSO BEEN REPORTED TO PLAY A ROLE. EARLY TREATMENT OF DIABETES HAS PROVEN TO BE OF GREAT BENEFIT, AS EVEN TRANSIENT HYPERGLYCEMIA MAY LEAD TO PATHOLOGICAL EFFECTS AND COMPLICATIONS LATER ON. THIS HAS BEEN EXPLAINED BY THE THEORY OF THE DEVELOPMENT OF A METABOLIC MEMORY IN DIABETES. THE BASIS FOR THIS METABOLIC MEMORY WAS ATTRIBUTED TO OXIDATIVE STRESS, CHRONIC INFLAMMATION, NON-ENZYMATIC GLYCATION OF PROTEINS AND IMPORTANTLY, EPIGENETIC CHANGES. THIS HIGHLIGHTS THE IMPORTANCE OF LINKING NEW THERAPEUTICS TARGETING EPIGENETIC MECHANISMS WITH TRADITIONAL ANTIDIABETIC DRUGS. CONCLUSION: ALTHOUGH NEW DATA IS EVOLVING ON THE RELATION BETWEEN DNA METHYLATION, PROTEIN MISFOLDING, AND THE ETIOLOGY OF DIABETES, MORE STUDIES ARE REQUIRED FOR DEVELOPING NEW RELEVANT DIAGNOSTICS AND THERAPEUTICS. 2019