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 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 3 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 4 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 5 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 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 6277 31 THE PATHOGENIC ROLE OF PERSISTENT MILK SIGNALING IN MTORC1- AND MILK-MICRORNA-DRIVEN TYPE 2 DIABETES MELLITUS. MILK, THE SECRETORY PRODUCT OF THE LACTATION GENOME, PROMOTES GROWTH OF THE NEWBORN MAMMAL. MILK DELIVERS INSULINOTROPIC AMINO ACIDS, THUS MAINTAINS A MOLECULAR CROSSTALK WITH THE PANCREATIC BETA-CELL OF THE MILK RECIPIENT. HOMEOSTASIS OF BETA-CELLS AND INSULIN PRODUCTION DEPEND ON THE APPROPRIATE MAGNITUDE OF MTORC1 SIGNALING. MTORC1 IS ACTIVATED BY BRANCHED-CHAIN AMINO ACIDS (BCAAS), GLUTAMINE, AND PALMITIC ACID, ABUNDANT NUTRIENT SIGNALS OF COW S MILK. FURTHERMORE, MILK DELIVERS BIOACTIVE EXOSOMAL MICRORNAS. AFTER MILK CONSUMPTION, BOVINE MICRORNA-29B, A MEMBER OF THE DIABETOGENIC MICRORNA-29- FAMILY, REACHES THE SYSTEMIC CIRCULATION AND THE CELLS OF THE MILK CONSUMER. MICRORNA-29B DOWNREGULATES BRANCHEDCHAIN ALPHA-KETOACID DEHYDROGENASE, A POTENTIAL EXPLANATION FOR INCREASED BCAA SERUM LEVELS, THE METABOLIC SIGNATURE OF INSULIN RESISTANCE AND TYPE 2 DIABETES MELLITUS (T2DM). IN NON-OBESE DIABETIC MICE, MICRORNA-29B DOWNREGULATES THE ANTIAPOPTOTIC PROTEIN MCL-1, WHICH LEADS TO EARLY BETA-CELL DEATH. IN ALL MAMMALS EXCEPT NEOLITHIC HUMANS, MILK-DRIVEN MTORC1 SIGNALING IS PHYSIOLOGICALLY RESTRICTED TO THE POSTNATAL PERIOD. IN CONTRAST, CHRONIC HYPERACTIVATED MTORC1 SIGNALING HAS BEEN ASSOCIATED WITH THE DEVELOPMENT OF AGE-RELATED DISEASES OF CIVILIZATION INCLUDING T2DM. NOTABLY, CHRONIC HYPERACTIVATION OF MTORC1 ENHANCES ENDOPLASMIC RETICULUM STRESS THAT PROMOTES APOPTOSIS. IN FACT, HYPERACTIVATED BETA-CELL MTORC1 SIGNALING INDUCED EARLY BETA-CELL APOPTOSIS IN A MOUSE MODEL. THE EPIC-INTERACT STUDY DEMONSTRATED AN ASSOCIATION BETWEEN MILK CONSUMPTION AND T2DM IN FRANCE, ITALY, UNITED KINGDOM, GERMANY, AND SWEDEN. IN CONTRAST, FERMENTED MILK PRODUCTS AND CHEESE EXHIBIT AN INVERSE CORRELATION. SINCE THE EARLY 1950 S, REFRIGERATION TECHNOLOGY ALLOWED WIDESPREAD CONSUMPTION OF FRESH PASTEURIZED MILK, WHICH FACILITATES DAILY INTAKE OF BIOACTIVE BOVINE MICRORNAS. PERSISTENT UPTAKE OF COW S MILK-DERIVED MICRORNAS APPARENTLY TRANSFERS AN OVERLOOKED EPIGENETIC DIABETOGENIC PROGRAM THAT SHOULD NOT REACH THE HUMAN FOOD CHAIN. 2015 8 2702 26 EXCITOTOXICITY AND OVERNUTRITION ADDITIVELY IMPAIR METABOLIC FUNCTION AND IDENTITY OF PANCREATIC BETA-CELLS. A SUSTAINED INCREASE IN INTRACELLULAR CA(2+) CONCENTRATION (REFERRED TO HEREAFTER AS EXCITOTOXICITY), BROUGHT ON BY CHRONIC METABOLIC STRESS, MAY CONTRIBUTE TO PANCREATIC BETA-CELL FAILURE. TO DETERMINE THE ADDITIVE EFFECTS OF EXCITOTOXICITY AND OVERNUTRITION ON BETA-CELL FUNCTION AND GENE EXPRESSION, WE ANALYZED THE IMPACT OF A HIGH-FAT DIET (HFD) ON ABCC8 KNOCKOUT MICE. EXCITOTOXICITY CAUSED BETA-CELLS TO BE MORE SUSCEPTIBLE TO HFD-INDUCED IMPAIRMENT OF GLUCOSE HOMEOSTASIS, AND THESE EFFECTS WERE MITIGATED BY VERAPAMIL, A CA(2+) CHANNEL BLOCKER. EXCITOTOXICITY, OVERNUTRITION, AND THE COMBINATION OF BOTH STRESSES CAUSED SIMILAR BUT DISTINCT ALTERATIONS IN THE BETA-CELL TRANSCRIPTOME, INCLUDING ADDITIVE INCREASES IN GENES ASSOCIATED WITH MITOCHONDRIAL ENERGY METABOLISM, FATTY ACID BETA-OXIDATION, AND MITOCHONDRIAL BIOGENESIS AND THEIR KEY REGULATOR PPARGC1A OVERNUTRITION WORSENED EXCITOTOXICITY-INDUCED MITOCHONDRIAL DYSFUNCTION, INCREASING METABOLIC INFLEXIBILITY AND MITOCHONDRIAL DAMAGE. IN ADDITION, EXCITOTOXICITY AND OVERNUTRITION, INDIVIDUALLY AND TOGETHER, IMPAIRED BOTH BETA-CELL FUNCTION AND IDENTITY BY REDUCING EXPRESSION OF GENES IMPORTANT FOR INSULIN SECRETION, CELL POLARITY, CELL JUNCTION, CILIA, CYTOSKELETON, VESICULAR TRAFFICKING, AND REGULATION OF BETA-CELL EPIGENETIC AND TRANSCRIPTIONAL PROGRAM. SEX HAD AN IMPACT ON ALL BETA-CELL RESPONSES, WITH MALE ANIMALS EXHIBITING GREATER METABOLIC STRESS-INDUCED IMPAIRMENTS THAN FEMALES. TOGETHER, THESE FINDINGS INDICATE THAT A SUSTAINED INCREASE IN INTRACELLULAR CA(2+), BY ALTERING MITOCHONDRIAL FUNCTION AND IMPAIRING BETA-CELL IDENTITY, AUGMENTS OVERNUTRITION-INDUCED BETA-CELL FAILURE. 2020 9 6608 36 TYPE I INTERFERONS AS KEY PLAYERS IN PANCREATIC BETA-CELL DYSFUNCTION IN TYPE 1 DIABETES. TYPE 1 DIABETES (T1D) IS A CHRONIC AUTOIMMUNE DISEASE CHARACTERIZED BY PANCREATIC ISLET INFLAMMATION (INSULITIS) AND SPECIFIC PANCREATIC BETA-CELL DESTRUCTION BY AN IMMUNE ATTACK. ALTHOUGH THE PRECISE UNDERLYING MECHANISMS LEADING TO THE AUTOIMMUNE ASSAULT REMAIN POORLY UNDERSTOOD, IT IS WELL ACCEPTED THAT INSULITIS TAKES PLACE IN THE CONTEXT OF A CONFLICTING DIALOGUE BETWEEN PANCREATIC BETA-CELLS AND THE IMMUNE CELLS. MOREOVER, BOTH HOST GENETIC BACKGROUND (I.E., CANDIDATE GENES) AND ENVIRONMENTAL FACTORS (E.G., VIRAL INFECTIONS) CONTRIBUTE TO THIS INADEQUATE DIALOGUE. ACCUMULATING EVIDENCE INDICATES THAT TYPE I INTERFERONS (IFNS), CYTOKINES THAT ARE CRUCIAL FOR BOTH INNATE AND ADAPTIVE IMMUNE RESPONSES, ACT AS KEY LINKS BETWEEN ENVIRONMENTAL AND GENETIC RISK FACTORS IN THE DEVELOPMENT OF T1D. THIS CHAPTER SUMMARIZES SOME RELEVANT PATHWAYS INVOLVED IN BETA-CELL DYSFUNCTION AND DEATH, AND BRIEFLY REVIEWS HOW ENTEROVIRAL INFECTIONS AND GENETIC SUSCEPTIBILITY CAN IMPACT INSULITIS. MOREOVER, WE PRESENT THE CURRENT EVIDENCE SHOWING THAT, IN BETA-CELLS, TYPE I IFN SIGNALING PATHWAY ACTIVATION LEADS TO SEVERAL OUTCOMES, SUCH AS LONG-LASTING MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) CLASS I HYPEREXPRESSION, ENDOPLASMIC RETICULUM (ER) STRESS, EPIGENETIC CHANGES, AND INDUCTION OF POSTTRANSCRIPTIONAL AS WELL AS POSTTRANSLATIONAL MODIFICATIONS. MHC CLASS I OVEREXPRESSION, WHEN COMBINED WITH ER STRESS AND POSTTRANSCRIPTIONAL/POSTTRANSLATIONAL MODIFICATIONS, MIGHT LEAD TO SUSTAINED NEOANTIGEN PRESENTATION TO IMMUNE SYSTEM AND BETA-CELL APOPTOSIS. THIS KNOWLEDGE SUPPORTS THE CONCEPT THAT TYPE I IFNS ARE IMPLICATED IN THE EARLY STAGES OF T1D PATHOGENESIS. FINALLY, WE HIGHLIGHT THE PROMISING THERAPEUTIC AVENUES FOR T1D TREATMENT DIRECTED AT TYPE I IFN SIGNALING PATHWAY. 2021 10 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 11 4070 37 MATERNAL DIABETES, PROGRAMMING OF BETA-CELL DISORDERS AND INTERGENERATIONAL RISK OF TYPE 2 DIABETES. A SUBSTANTIAL BODY OF EVIDENCE SUGGESTS THAT AN ABNORMAL INTRA-UTERINE MILIEU ELICITED BY MATERNAL METABOLIC DISTURBANCES AS DIVERSE AS MALNUTRITION, PLACENTAL INSUFFICIENCY, DIABETES AND OBESITY MAY BE ABLE TO PROGRAMME SUSCEPTIBILITY OF THE FOETUS TO LATER DEVELOP CHRONIC DEGENERATIVE DISEASES SUCH AS OBESITY, HYPERTENSION, CARDIOVASCULAR DISEASES AND TYPE 2 DIABETES (T2D). AS INSULIN-PRODUCING CELLS HAVE BEEN PLACED CENTRE STAGE IN THE DEVELOPMENT OF T2D, THIS REVIEW EXAMINES DEVELOPMENTAL PROGRAMMING OF THE BETA-CELL MASS (BCM) IN VARIOUS RODENT MODELS OF MATERNAL PROTEIN RESTRICTION, CALORIE RESTRICTION, OVERNUTRITION AND DIABETES. THE MAIN MESSAGE IS THAT WHATEVER THE INITIAL MATERNAL INSULT (F0 GENERATION) AND WHETHER ALONE OR IN COMBINATION, IT GIVES RISE TO THE SAME PROGRAMMED BCM OUTCOME IN THE DAUGHTER GENERATION (F1). THE ALTERED BCM PHENOTYPE IN F1 FEMALES PROHIBITS NORMAL BCM ADAPTATION DURING PREGNANCY AND, THUS, DIABETES (GESTATIONAL DIABETES) ENSUES. THIS GESTATIONAL DIABETES IS THEN PASSED FROM ONE GENERATION (F1) TO THE NEXT (F2, F3 AND SO ON). THIS REVIEW HIGHLIGHTS A NUMBER OF STUDIES THAT HAVE IDENTIFIED EPIGENETIC MECHANISMS THAT MAY CONTRIBUTE TO ALTERED BCM DEVELOPMENT AND BETA-CELL FAILURE, AS OBSERVED IN DIABETES. IN ADDITION TO THEIR ROLE IN INSTILLING THE PROGRAMMED DEFECT, THESE NON-GENOMIC MECHANISMS MAY ALSO BE INVOLVED IN ITS INTERGENERATIONAL TRANSMISSION. 2014 12 426 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 13 5293 28 PROTEASOMAL DEGRADATION OF THE HISTONE ACETYL TRANSFERASE P300 CONTRIBUTES TO BETA-CELL INJURY IN A DIABETES ENVIRONMENT. IN TYPE 2 DIABETES, AMYLOID OLIGOMERS, CHRONIC HYPERGLYCEMIA, LIPOTOXICITY, AND PRO-INFLAMMATORY CYTOKINES ARE DETRIMENTAL TO BETA-CELLS, CAUSING APOPTOSIS AND IMPAIRED INSULIN SECRETION. THE HISTONE ACETYL TRANSFERASE P300, INVOLVED IN REMODELING OF CHROMATIN STRUCTURE BY EPIGENETIC MECHANISMS, IS A KEY UBIQUITOUS ACTIVATOR OF THE TRANSCRIPTIONAL MACHINERY. IN THIS STUDY, WE REPORT THAT LOSS OF P300 ACETYL TRANSFERASE ACTIVITY AND EXPRESSION LEADS TO BETA-CELL APOPTOSIS, AND MOST IMPORTANTLY, THAT STRESS SITUATIONS KNOWN TO BE ASSOCIATED WITH DIABETES ALTER P300 LEVELS AND FUNCTIONAL INTEGRITY. WE FOUND THAT PROTEASOMAL DEGRADATION IS THE MECHANISM SUBSERVING P300 LOSS IN BETA-CELLS EXPOSED TO HYPERGLYCEMIA OR PRO-INFLAMMATORY CYTOKINES. WE ALSO REPORT THAT MELATONIN, A HORMONE PRODUCED IN THE PINEAL GLAND AND KNOWN TO PLAY KEY ROLES IN BETA-CELL HEALTH, PRESERVES P300 LEVELS ALTERED BY THESE TOXIC CONDITIONS. COLLECTIVELY, THESE DATA IMPLY AN IMPORTANT ROLE FOR P300 IN THE PATHOPHYSIOLOGY OF DIABETES. 2018 14 5060 25 PHENYLBUTYRATE AND BETA-CELL FUNCTION: CONTRIBUTION OF HISTONE DEACETYLASES AND ER STRESS INHIBITION. INCIDENCES OF DIABETES ARE INCREASING GLOBALLY DUE TO INVOLVEMENT OF GENETIC AND EPIGENETIC FACTORS. PHENYLBUTYRATE (PBA) IS A US FDA APPROVED DRUG FOR TREATMENT OF UREA CYCLE DISORDER IN CHILDREN. PBA REDUCES ENDOPLASMIC RETICULUM (ER) STRESS AND IS PROVEN AS A POTENT HISTONE DEACETYLASES (HDACS) INHIBITOR. CHRONIC ER STRESS RESULTS IN UNFOLDING PROTEIN RESPONSE, WHICH TRIGGERS APOPTOSIS. ABNORMAL ER HOMOEOSTASIS IS RESPONSIBLE FOR DEFECTIVE PROCESSING OF SEVERAL GENES/PROTEINS AND CONTRIBUTES TO BETA-CELL DEATH/FAILURE. ACCUMULATED EVIDENCES INDICATED THAT HDACS MODULATE KEY BIOCHEMICAL PATHWAYS AND HDAC INHIBITORS IMPROVE BETA-CELL FUNCTION AND INSULIN RESISTANCE BY MODULATING MULTIPLE TARGETS. THIS REVIEW HIGHLIGHTS THE ROLE OF PBA ON BETA-CELL FUNCTIONS, INSULIN RESISTANCE FOR POSSIBLE TREATMENT OF DIABETES THROUGH INHIBITION OF ER STRESS AND HDACS. 2017 15 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 16 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 17 6606 36 TYPE 2 DIABETES ACROSS GENERATIONS: FROM PATHOPHYSIOLOGY TO PREVENTION AND MANAGEMENT. TYPE 2 DIABETES IS NOW A PANDEMIC AND SHOWS NO SIGNS OF ABATEMENT. IN THIS SEMINAR WE REVIEW THE PATHOPHYSIOLOGY OF THIS DISORDER, WITH PARTICULAR ATTENTION TO EPIDEMIOLOGY, GENETICS, EPIGENETICS, AND MOLECULAR CELL BIOLOGY. EVIDENCE IS EMERGING THAT A SUBSTANTIAL PART OF DIABETES SUSCEPTIBILITY IS ACQUIRED EARLY IN LIFE, PROBABLY OWING TO FETAL OR NEONATAL PROGRAMMING VIA EPIGENETIC PHENOMENA. MATERNAL AND EARLY CHILDHOOD HEALTH MIGHT, THEREFORE, BE CRUCIAL TO THE DEVELOPMENT OF EFFECTIVE PREVENTION STRATEGIES. DIABETES DEVELOPS BECAUSE OF INADEQUATE ISLET BETA-CELL AND ADIPOSE-TISSUE RESPONSES TO CHRONIC FUEL EXCESS, WHICH RESULTS IN SO-CALLED NUTRIENT SPILLOVER, INSULIN RESISTANCE, AND METABOLIC STRESS. THE LATTER DAMAGES MULTIPLE ORGANS. INSULIN RESISTANCE, WHILE FORCING BETA CELLS TO WORK HARDER, MIGHT ALSO HAVE AN IMPORTANT DEFENSIVE ROLE AGAINST NUTRIENT-RELATED TOXIC EFFECTS IN TISSUES SUCH AS THE HEART. REVERSAL OF OVERNUTRITION, HEALING OF THE BETA CELLS, AND LESSENING OF ADIPOSE TISSUE DEFECTS SHOULD BE TREATMENT PRIORITIES. 2011 18 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 19 5296 30 PROTECTIVE ROLE OF SODIUM BUTYRATE, A HDAC INHIBITOR ON BETA-CELL PROLIFERATION, FUNCTION AND GLUCOSE HOMEOSTASIS THROUGH MODULATION OF P38/ERK MAPK AND APOPTOTIC PATHWAYS: STUDY IN JUVENILE DIABETIC RAT. TYPE 1 DIABETES (T1D) ALSO KNOWN AS JUVENILE DIABETES IS A CHRONIC AUTOIMMUNE DISORDER THAT PRECIPITATES IN GENETICALLY SUSCEPTIBLE INDIVIDUALS BY ENVIRONMENTAL FACTORS PARTICULARLY DURING EARLY AGE. BOTH GENETIC AND EPIGENETIC FACTORS ARE IMPLICATED IN THE BETA-CELL DEVELOPMENT, PROLIFERATION, DIFFERENTIATION AND FUNCTION. RECENT EVIDENCES SUGGESTED THAT THERE IS A LINK BETWEEN DIABETES AND HISTONE DEACETYLASES (HDACS), BECAUSE HDAC INHIBITORS PROMOTE BETA-CELL DEVELOPMENT, PROLIFERATION AND FUNCTION AS WELL AS IMPROVE GLUCOSE HOMEOSTASIS. SODIUM BUTYRATE (NAB) IS A SHORT CHAIN FATTY ACID HAVING HDAC INHIBITION ACTIVITY. THE PRESENT STUDY WAS AIMED TO INVESTIGATE THE PROTECTIVE ROLE OF NAB TREATMENT ON THE BETA-CELL PROLIFERATION, FUNCTION AND GLUCOSE HOMEOSTASIS AS WELL AS APOPTOSIS IN JUVENILE DIABETIC RAT. DIABETES WAS INDUCED BY SINGLE INJECTION OF STZ (60 MG/KG, I.P.) IN CHILLED CITRATE BUFFER, WHILE NAB (500 MG/KG/DAY) WAS ADMINISTRATED BY I.P. ROUTE FOR 21 DAYS AS PRE- AND POST-TREATMENT SCHEDULE. PLASMA GLUCOSE AND INSULIN LEVELS, HBA1C, GLUCOSE TOLERANCE, APOPTOSIS, AND EXPRESSION OF PROLIFERATING CELL NUCLEAR ANTIGEN (PCNA), P38, P53, CASPASE-3, EXTRACELLULAR SIGNAL-REGULATED KINASE-1/2 (ERK-1/2), FORKHEAD BOX PROTEIN O1 (FOXO1) AND INSULIN RECEPTOR SUBSTRATE-1 (IRS-1) AS WELL AS HISTONE ACETYLATION WERE EVALUATED. NAB TREATMENT DECREASED PLASMA GLUCOSE, HBA1C, BETA-CELL APOPTOSIS AND IMPROVED PLASMA INSULIN LEVEL AND GLUCOSE HOMEOSTASIS THROUGH HDAC INHIBITION AND HISTONE ACETYLATION IN DIABETIC ANIMAL AS COMPARED TO CONTROL. NAB TREATMENT IMPROVED THE BETA-CELL PROLIFERATION, FUNCTION AND GLUCOSE HOMEOSTASIS AS WELL AS REDUCED BETA-CELL APOPTOSIS IN JUVENILE DIABETIC RAT BY THE MODULATION OF P38/ERK MAPK AND APOPTOTIC PATHWAY. 2014 20 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