1 2444 142 EPIGENETIC STATES OF NEPHRON PROGENITORS AND EPITHELIAL DIFFERENTIATION. IN MAMMALS, FORMATION OF NEW NEPHRONS ENDS PERINATALLY DUE TO CONSUMPTION OF MESENCHYMAL PROGENITOR CELLS. PREMATURE DEPLETION OF PROGENITORS DUE TO PREMATURITY OR POSTNATAL LOSS OF NEPHRONS DUE TO INJURY CAUSES CHRONIC KIDNEY DISEASE AND HYPERTENSION. INTENSIVE EFFORTS ARE CURRENTLY INVESTED IN DESIGNING REGENERATIVE STRATEGIES TO FORM NEW NEPHRON PROGENITORS FROM PLURIPOTENT CELLS, WHICH UPON FURTHER DIFFERENTIATION PROVIDE A POTENTIAL SOURCE OF NEW NEPHRONS. TO KNOW IF REPROGRAMED RENAL CELLS CAN MAINTAIN THEIR IDENTITY AND FATE REQUIRES KNOWLEDGE OF THE EPIGENETIC STATES OF NATIVE NEPHRON PROGENITORS AND THEIR PROGENY. IN THIS ARTICLE, WE SUMMARIZE CURRENT KNOWLEDGE AND GAPS IN THE EPIGENOMIC LANDSCAPE OF THE DEVELOPING KIDNEY. WE NOW KNOW THAT PAX2/PTIP/H3K4 METHYLTRANSFERASE ACTIVITY PROVIDES THE INITIAL EPIGENETIC SPECIFICATION SIGNAL TO THE METANEPHRIC MESENCHYME. DURING NEPHROGENESIS, THE CAP MESENCHYME HOUSING NEPHRON PROGENITORS IS ENRICHED IN BIVALENT CHROMATIN MARKS; AS TUBULOGENESIS PROCEEDS, THE TUBULAR EPITHELIUM ACQUIRES H3K79ME2. THE LATTER MARK IS UNIQUELY INDUCED DURING EPITHELIAL DIFFERENTIATION. ANALYSIS OF HISTONE LANDSCAPES IN CLONAL METANEPHRIC MESENCHYME CELL LINES AND IN WILMS TUMOR AND NORMAL FETAL KIDNEY HAS REVEALED THAT PROMOTERS OF POISED NEPHROGENESIS GENES CARRY BIVALENT HISTONE SIGNATURES IN PROGENITORS. DIFFERENTIATION OR STIMULATION OF WNT SIGNALING PROMOTES RESOLUTION OF BIVALENCY; THIS DOES NOT OCCUR IN WILMS TUMOR CELLS CONSISTENT WITH THEIR DEVELOPMENTAL ARREST. THE USE OF SMALL CELL NUMBER CHIP-SEQ SHOULD FACILITATE THE CHARACTERIZATION OF THE CHROMATIN LANDSCAPE OF THE METANEPHRIC MESENCHYME AND VARIOUS NEPHRON COMPARTMENTS DURING NEPHROGENESIS. ONLY THEN WE WILL KNOW IF STEM AND SOMATIC CELL REPROGRAMMING INTO KIDNEY PROGENITORS RECAPITULATES NORMAL DEVELOPMENT. 2015 2 2566 51 EPIGENETICS MECHANISMS IN RENAL DEVELOPMENT. APPRECIATION FOR THE ROLE OF EPIGENETIC MODIFICATIONS IN THE DIAGNOSIS AND TREATMENT OF DISEASES IS FAST GAINING ATTENTION. TREATMENT OF CHRONIC KIDNEY DISEASE STEMMING FROM DIABETES OR HYPERTENSION AS WELL AS WILMS TUMOR WILL ALL PROFIT FROM KNOWLEDGE OF THE CHANGES IN THE EPIGENOMIC LANDSCAPES. TO DO SO, IT IS ESSENTIAL TO CHARACTERIZE THE EPIGENOMIC MODIFIERS AND THEIR MODIFICATIONS UNDER NORMAL PHYSIOLOGICAL CONDITIONS. THE TRANSCRIPTION FACTOR PAX2 WAS IDENTIFIED AS A MAJOR EPIGENETIC PLAYER IN THE EARLY SPECIFICATION OF THE KIDNEY. NOTABLY, THE PROGENITORS OF ALL NEPHRONS THAT RESIDE IN THE CAP MESENCHYME DISPLAY A UNIQUE BIVALENT HISTONE SIGNATURE (EXPRESSING REPRESSIVE EPIGENETIC MARKS ALONGSIDE ACTIVATION MARKS) ON LINEAGE-SPECIFIC GENES. THESE CELLS ARE DEEMED POISED FOR DIFFERENTIATION AND COMMITMENT TO THE NEPHROGENIC LINEAGE. IN RESPONSE TO THE APPROPRIATE INDUCING SIGNAL, THESE GENES LOSE THEIR REPRESSIVE HISTONE MARKS, WHICH ALLOW FOR THEIR EXPRESSION IN NASCENT NEPHRON PRECURSORS. SUCH KNOWLEDGE OF THE EPIGENETIC LANDSCAPE AND THE RESULTANT CELL FATE OR BEHAVIOR IN THE DEVELOPING KIDNEY WILL GREATLY IMPROVE THE OVERALL SUCCESS IN DESIGNING REGENERATIVE STRATEGIES AND TISSUE REPROGRAMMING METHODOLOGIES FROM PLURIPOTENT CELLS. 2016 3 5403 33 REGENERATION AFTER ACUTE KIDNEY INJURY REQUIRES PTIP-MEDIATED EPIGENETIC MODIFICATIONS. A TERMINALLY DIFFERENTIATED CELLULAR PHENOTYPE IS THOUGHT TO BE MAINTAINED, AT LEAST IN PART, BY BOTH ACTIVE AND REPRESSIVE HISTONE MARKS. HOWEVER, IT IS UNCLEAR WHETHER REGENERATING CELLS AFTER INJURY NEED TO REPLICATE SUCH EPIGENETIC MARKS TO RECOVER. TO TEST WHETHER RENAL EPITHELIAL CELL REGENERATION IS DEPENDENT ON HISTONE H3K4 METHYLATION, WE GENERATED A MOUSE MODEL THAT DELETED THE PAXIP1 GENE IN MATURE RENAL PROXIMAL TUBULES. PAXIP1 ENCODES PTIP, AN ESSENTIAL PROTEIN IN THE MLL3/4 HISTONE H3K4 METHYLTRANSFERASE COMPLEX. MICE WITH PTIP DELETIONS IN THE ADULT KIDNEY PROXIMAL TUBULES WERE VIABLE AND FERTILE. UPON ACUTE KIDNEY INJURY, SUCH MICE FAILED TO REGENERATE DAMAGED TUBULES, LEADING TO SCARRING AND INTERSTITIAL FIBROSIS. THE INABILITY TO REPAIR DAMAGE WAS LIKELY DUE TO A FAILURE TO REENTER MITOSIS AND REACTIVATE REGULATORY GENES SUCH AS SOX9. PTIP DELETION REDUCED HISTONE H3K4 METHYLATION IN UNINJURED ADULT KIDNEYS BUT DID NOT SIGNIFICANTLY AFFECT FUNCTION OR THE EXPRESSION OF EPITHELIAL SPECIFIC MARKERS. STRIKINGLY, CELL LINEAGE TRACING REVEALED THAT SURVIVING PTIP MUTANT CELLS COULD ALTER THEIR PHENOTYPE AND LOSE EPITHELIAL MARKERS. THESE DATA DEMONSTRATE THAT PTIP AND ASSOCIATED MLL3/4-MEDIATED HISTONE METHYLATION ARE NEEDED FOR REGENERATING PROXIMAL TUBULES AND TO MAINTAIN OR REESTABLISH THE CELLULAR EPITHELIAL PHENOTYPE. 2020 4 1359 29 DEVELOPMENT REFRACTORINESS OF MLL-REARRANGED HUMAN B CELL ACUTE LEUKEMIAS TO REPROGRAMMING INTO PLURIPOTENCY. INDUCED PLURIPOTENT STEM CELLS (IPSCS) ARE A POWERFUL TOOL FOR DISEASE MODELING. THEY ARE ROUTINELY GENERATED FROM HEALTHY DONORS AND PATIENTS FROM MULTIPLE CELL TYPES AT DIFFERENT DEVELOPMENTAL STAGES. HOWEVER, REPROGRAMMING LEUKEMIAS IS AN EXTREMELY INEFFICIENT PROCESS. FEW STUDIES GENERATED IPSCS FROM PRIMARY CHRONIC MYELOID LEUKEMIAS, BUT IPSC GENERATION FROM ACUTE MYELOID OR LYMPHOID LEUKEMIAS (ALL) HAS NOT BEEN ACHIEVED. WE ATTEMPTED TO GENERATE IPSCS FROM DIFFERENT SUBTYPES OF B-ALL TO ADDRESS THE DEVELOPMENTAL IMPACT OF LEUKEMIC FUSION GENES. OKSM(L)-EXPRESSING MONO/POLYCISTRONIC-, RETROVIRAL/LENTIVIRAL/EPISOMAL-, AND SENDAI VIRUS VECTOR-BASED REPROGRAMMING STRATEGIES FAILED TO RENDER IPSCS IN VITRO AND IN VIVO. ADDITION OF TRANSCRIPTOMIC-EPIGENETIC REPROGRAMMING "BOOSTERS" ALSO FAILED TO GENERATE IPSCS FROM B CELL BLASTS AND B-ALL LINES, AND WHEN IPSCS EMERGED THEY LACKED LEUKEMIC FUSION GENES, DEMONSTRATING NON-LEUKEMIC MYELOID ORIGIN. CONVERSELY, MLL-AF4-OVEREXPRESSING HEMATOPOIETIC STEM CELLS/B PROGENITORS WERE SUCCESSFULLY REPROGRAMMED, INDICATING THAT B CELL ORIGIN AND LEUKEMIC FUSION GENE WERE NOT REPROGRAMMING BARRIERS. GLOBAL TRANSCRIPTOME/DNA METHYLOME PROFILING SUGGESTED A DEVELOPMENTAL/DIFFERENTIATION REFRACTORINESS OF MLL-REARRANGED B-ALL TO REPROGRAMMING INTO PLURIPOTENCY. 2016 5 794 28 CELLULAR REPROGRAMMING IN BASIC AND APPLIED BIOMEDICINE: THE DAWN OF REGENERATIVE MEDICINE. FERTILIZATION TRIGGERS A CASCADE OF CELLULAR AND MOLECULAR EVENTS RESTORING THE TOTIPOTENT STATE AND THE POTENTIAL FOR ALL CELL TYPES. HOWEVER, THE PROGRAM QUICKLY DIRECTS DIFFERENTIATION AND CELLULAR COMMITMENT. UNDER THE GENETIC AND EPIGENETIC CONTROL OF THIS PROCESS, WADDINGTON LIKENED THIS TO A THREE-DIMENSIONAL LANDSCAPE WHERE CELLS COULD NOT ASCEND THE SLOPE OR TRAVERSE ONCE CANALIZED THUS LEADING TO CELL FATE DECISIONS AND THE PROGRESSIVE RESTRICTION OF CELLULAR POTENCY. BUT THIS IS NOT THE ONLY POSSIBLE OUTCOME AT LEAST EXPERIMENTALLY. SOMATIC CELL NUCLEAR TRANSFER AND OVEREXPRESSION OF KEY TRANSCRIPTION FACTORS TO GENERATE INDUCED PLURIPOTENT CELLS HAVE CHALLENGED THIS NOTION. THE RETURN TO PLURIPOTENCY AND THE REINSTATEMENT OF PLASTICITY AND HETEROGENEITY ONCE THOUGHT TO BE THE EXCLUSIVE REMIT OF THE DEVELOPING EMBRYO CAN NOW BE REPLICATED IN VITRO. THE FOLLOWING CHAPTER INTRODUCES SOME OF THESE IDEAS AND SUGGESTS THAT THE FUNDAMENTAL PRINCIPLES LEARNED MAY CONSTITUTE THE FIRST STEP TOWARD THE OPPORTUNITY FOR SPECIFIC TISSUE RENEWAL AND REPLACEMENT IN HEALTHY AGING AND THE TREATMENT OF CHRONIC DISEASES-THE AGE OF REGENERATIVE MEDICINE. 2015 6 2866 25 FUNCTIONAL ADULT ACETYLCHOLINE RECEPTOR DEVELOPS INDEPENDENTLY OF MOTOR INNERVATION IN SOL 8 MOUSE MUSCLE CELL LINE. WE HAVE DEFINED CULTURE CONDITIONS, USING A FEEDER LAYER OF CELLS FROM THE EMBRYONIC MESENCHYMAL CELL LINE, 10T1/2 AND A SERUM-FREE MEDIUM, WHICH ALLOW CELLS FROM THE MOUSE MYOGENIC CELL LINE SOL 8 TO FORM CONTRACTING MYOTUBES FOR TWO WEEKS. UNDER THESE CULTURE CONDITIONS, SOL 8 MYOTUBES UNDERGO A MATURATION PROCESS CHARACTERIZED BY A SEQUENTIAL EXPRESSION OF TWO PHENOTYPES. AN EARLY PHENOTYPE IS TYPIFIED BY THE EXPRESSION OF THE NICOTINIC ACETYLCHOLINE RECEPTOR (ACHR) GAMMA-SUBUNIT TRANSCRIPTS AND THE PRESENCE OF LOW CONDUCTANCE ACH-ACTIVATED CHANNELS, TYPICAL OF EMBRYONIC ACHR. A LATE PHENOTYPE IS CHARACTERIZED BY THE EXPRESSION OF ACHR EPSILON-SUBUNIT TRANSCRIPTS, THE DECREASED ACCUMULATION OF GAMMA-SUBUNIT TRANSCRIPTS AND THE APPEARANCE OF HIGH CONDUCTANCE ACH-ACTIVATED CHANNELS, TYPICAL OF ADULT ACHR. THESE RESULTS INDICATE THAT THE EXPRESSION OF FUNCTIONAL ADULT TYPE ACHR DOES NOT REQUIRE THE PRESENCE OF THE MOTOR NERVE AND THEREFORE REPRESENTS AN INTRINSIC FEATURE OF THE SOL 8 MUSCLE CELLS. CHRONIC EXPOSURE OF THE CELLS TO THE VOLTAGE-SENSITIVE NA+ CHANNEL BLOCKING AGENT TETRODOTOXIN DOES NOT AFFECT THE APPEARANCE OF THE ACHR EPSILON-SUBUNIT TRANSCRIPTS BUT PREVENTS THE REDUCTION OF THE STEADY-STATE LEVEL OF THE ACHR GAMMA-SUBUNIT TRANSCRIPTS AND YIELDS A REDUCED PROPORTION OF THE ADULT TYPE CHANNELS. THUS, ACTIVITY SEEMS TO FACILITATE THE SWITCH FROM THE EMBRYONIC TO THE ADULT PHENOTYPE OF THE ACHR PROTEIN. THE SOL 8 CELL SYSTEM MIGHT BE USEFUL TO ANALYSE FURTHER THE GENETIC AND EPIGENETIC REGULATION OF MUSCLE FIBRE MATURATION IN MAMMALS. 1991 7 4513 26 MULTI-OMIC APPROACHES TO ACUTE KIDNEY INJURY AND REPAIR. THE KIDNEY HAS A REMARKABLE REGENERATIVE CAPACITY. IN RESPONSE TO ISCHEMIC OR TOXIC INJURY, PROXIMAL TUBULE CELLS CAN PROLIFERATE TO REBUILD DAMAGED TUBULES AND RESTORE KIDNEY FUNCTION. HOWEVER, SEVERE ACUTE KIDNEY INJURY (AKI) OR RECURRENT AKI EVENTS CAN LEAD TO MALADAPTIVE REPAIR AND DISEASE PROGRESSION FROM AKI TO CHRONIC KIDNEY DISEASE (CKD). THE APPLICATION OF SINGLE CELL TECHNOLOGIES HAS IDENTIFIED INJURED PROXIMAL TUBULE CELL STATES WEEKS AFTER AKI, DISTINGUISHED BY A PRO-INFLAMMATORY SENESCENT MOLECULAR SIGNATURE. EPIGENETIC STUDIES HIGHLIGHTED DYNAMIC CHANGES IN THE CHROMATIN LANDSCAPE OF THE KIDNEY FOLLOWING AKI AND DESCRIBED KEY TRANSCRIPTION FACTORS LINKED TO THE AKI RESPONSE. THE INTEGRATION OF MULTI-OMIC TECHNOLOGIES OPENS NEW POSSIBILITIES TO IMPROVE OUR UNDERSTANDING OF AKI AND THE DRIVING FORCES BEHIND THE AKI-TO-CKD TRANSITION, WITH THE ULTIMATE GOAL OF DESIGNING TAILORED DIAGNOSTIC AND THERAPEUTIC STRATEGIES TO IMPROVE AKI OUTCOMES AND PREVENT KIDNEY DISEASE PROGRESSION. 2021 8 1824 28 EFFECTS OF ENVIRONMENTAL CONDITIONS ON NEPHRON NUMBER: MODELING MATERNAL DISEASE AND EPIGENETIC REGULATION IN RENAL DEVELOPMENT. A GROWING BODY OF EVIDENCE SUGGESTS THAT LOW NEPHRON NUMBERS AT BIRTH CAN INCREASE THE RISK OF CHRONIC KIDNEY DISEASE OR HYPERTENSION LATER IN LIFE. ENVIRONMENTAL STRESSORS, SUCH AS MATERNAL MALNUTRITION, MEDICATION AND SMOKING, CAN INFLUENCE RENAL SIZE AT BIRTH. USING METANEPHRIC ORGAN CULTURES TO MODEL SINGLE-VARIABLE ENVIRONMENTAL CONDITIONS, MODELS OF MATERNAL DISEASE WERE EVALUATED FOR PATTERNS OF DEVELOPMENTAL IMPAIRMENT. WHILE HYPERTHERMIA HAD LIMITED EFFECTS ON RENAL DEVELOPMENT, FETAL IRON DEFICIENCY WAS ASSOCIATED WITH SEVERE IMPAIRMENT OF RENAL GROWTH AND NEPHROGENESIS WITH AN ALL-PROXIMAL PHENOTYPE. CULTURING KIDNEY EXPLANTS UNDER HIGH GLUCOSE CONDITIONS LED TO CELLULAR AND TRANSCRIPTOMIC CHANGES RESEMBLING HUMAN DIABETIC NEPHROPATHY. SHORT-TERM HIGH GLUCOSE CULTURE CONDITIONS WERE SUFFICIENT FOR LONG-TERM ALTERATIONS IN DNA METHYLATION-ASSOCIATED EPIGENETIC MEMORY. FINALLY, THE ROLE OF EPIGENETIC MODIFIERS IN RENAL DEVELOPMENT WAS TESTED USING A SMALL COMPOUND LIBRARY. AMONG THE SELECTED EPIGENETIC INHIBITORS, VARIOUS COMPOUNDS ELICITED AN EFFECT ON RENAL GROWTH, SUCH AS HDAC (ENTINOSTAT, TH39), HISTONE DEMETHYLASE (DEFERASIROX, DEFEROXAMINE) AND HISTONE METHYLTRANSFERASE (CYPROHEPTADINE) INHIBITORS. THUS, METANEPHRIC ORGAN CULTURES PROVIDE A VALUABLE SYSTEM FOR STUDYING METABOLIC CONDITIONS AND A TOOL FOR SCREENING FOR EPIGENETIC MODIFIERS IN RENAL DEVELOPMENT. 2021 9 595 30 BET PROTEINS REGULATE EXPRESSION OF OSR1 IN EARLY KIDNEY DEVELOPMENT. IN UTERO RENAL DEVELOPMENT IS SUBJECT TO MATERNAL METABOLIC AND ENVIRONMENTAL INFLUENCES AFFECTING LONG-TERM RENAL FUNCTION AND THE RISK OF DEVELOPING CHRONIC KIDNEY FAILURE AND CARDIOVASCULAR DISEASE. EPIGENETIC PROCESSES HAVE BEEN IMPLICATED IN THE ORCHESTRATION OF RENAL DEVELOPMENT AND PRENATAL PROGRAMMING OF NEPHRON NUMBER. HOWEVER, THE ROLE OF MANY EPIGENETIC MODIFIERS FOR KIDNEY DEVELOPMENT IS STILL UNCLEAR. BROMODOMAIN AND EXTRA-TERMINAL DOMAIN (BET) PROTEINS ACT AS HISTONE ACETYLATION READER MOLECULES AND PROMOTE GENE TRANSCRIPTION. BET FAMILY MEMBERS BRD2, BRD3 AND BRD4 ARE EXPRESSED IN THE NEPHROGENIC ZONE DURING KIDNEY DEVELOPMENT. HERE, THE EFFECT OF THE BET INHIBITOR JQ1 ON RENAL DEVELOPMENT IS EVALUATED. INHIBITION OF BET PROTEINS VIA JQ1 LEADS TO REDUCED GROWTH OF METANEPHRIC KIDNEY CULTURES, LOSS OF THE NEPHRON PROGENITOR CELL POPULATION, AND PREMATURE AND DISTURBED NEPHRON DIFFERENTIATION. GENE EXPRESSION OF KEY NEPHRON PROGENITOR TRANSCRIPTION FACTOR OSR1 IS DOWNREGULATED AFTER 24 H BET INHIBITION, WHILE LHX1 AND PAX8 EXPRESSION IS INCREASED. MINING OF BRD4 CHIP-SEQ AND GENE EXPRESSION DATA IDENTIFY OSR1 AS A KEY FACTOR REGULATED BY BRD4-CONTROLLED GENE ACTIVATION. INHIBITION OF BRD4 BY BET INHIBITOR JQ1 LEADS TO DOWNREGULATION OF OSR1, THEREBY CAUSING A DISTURBANCE IN THE BALANCE OF NEPHRON PROGENITOR CELL SELF-RENEWAL AND PREMATURE DIFFERENTIATION OF THE NEPHRON, WHICH ULTIMATELY LEADS TO KIDNEY HYPOPLASIA AND DISTURBED NEPHRON DEVELOPMENT. THIS RAISES QUESTIONS ABOUT THE POTENTIAL TERATOGENIC EFFECTS OF BET INHIBITORS FOR EMBRYONIC DEVELOPMENT. IN SUMMARY, OUR WORK HIGHLIGHTS THE ROLE OF BET PROTEINS FOR PRENATAL PROGRAMMING OF NEPHROGENESIS AND IDENTIFIES OSR1 AS A POTENTIAL TARGET OF BET PROTEINS. 2021 10 1378 29 DEVELOPMENTAL PROGRAMS ARE KEPT ALIVE DURING ADULTHOOD BY STEM CELLS: THE AGING ASPECT. STEM CELLS ARE FUNDAMENTAL FOR LIFE-LONG PRESERVATION OF CELLULAR SOMATIC MAINTENANCE. TISSUE-BORNE STEM CELLS REPLENISH WORN-OUT CRITICAL ELEMENTS. PROVIDED THEY REMAIN FIT OVER LIFETIME, ENDURING STEM CELL ACTIVITIES AVERT THE EMERGENCE OF AGE-ASSOCIATED CHRONIC DEGENERATIVE DISEASES AND PATHOLOGIES. ALTHOUGH EXPERIMENTALLY STILL UNCLEAR, IT IS ASSUMED THAT STEM CELLS RESIDE IN PROTECTED NICHES. FRESHLY ISOLATED MESENCHYMAL STEM CELLS EXHIBIT DONOR-SPECIFIC ABERRATIONS, WHICH CANNOT SOLELY BE ASCRIBED TO DIFFERENCES IN GENETIC BACKGROUND. BESIDES INEVITABLY ACCUMULATING INTRINSIC MODIFICATIONS, THE SYSTEMIC ENVIRONMENT ALSO IMPACTS ON BASIC PROPERTIES OF MESENCHYMAL STEM CELLS SUCH AS THEIR INHERENT MULTI-LINEAGE DIFFERENTIATION POTENTIAL. CHRONIC SYSTEMIC ABERRATIONS OVER TIME COMPRISE UNWHOLESOME INFLUENCES, IN PARTICULAR IN TERMS OF REGENERATION AND REPAIR WHEN STEM CELLS RECAPITULATE DISTINCT DEVELOPMENTAL PROGRAMS. DURING OR THEREAFTER, STEM CELLS CAN DIVERSIFY EITHER BECAUSE OF INSUFFICIENTLY SILENCING ACTIVATED BUILDING CYCLES, OR BY ACQUIRING EPIGENETIC DEVIATIONS. 2013 11 5440 38 RENAL DIFFERENTIATION OF AMNIOTIC FLUID STEM CELLS: PERSPECTIVES FOR CLINICAL APPLICATION AND FOR STUDIES ON SPECIFIC HUMAN GENETIC DISEASES. BACKGROUND: OWING TO GROWING RATES OF DIABETES, HYPERTENSION AND THE AGEING POPULATION, THE PREVALENCE OF END-STAGE RENAL DISEASE, DEVELOPED FROM EARLIER STAGES OF CHRONIC KIDNEY DISEASE, AND OF ACUTE RENAL FAILURE IS DRAMATICALLY INCREASING. DIALYSIS AND PREFERABLE RENAL TRANSPLANTATION ARE WIDELY APPLIED THERAPIES FOR THIS INCURABLE CONDITION. HOWEVER THESE OPTIONS ARE LIMITED BECAUSE OF MORBIDITY, SHORTAGE OF COMPATIBLE ORGANS AND COSTS. THEREFORE, STEM CELL-BASED APPROACHES ARE BECOMING INCREASINGLY ACCEPTED AS AN ALTERNATIVE THERAPEUTIC STRATEGY. DESIGN: THIS REVIEW SUMMARIZES THE CURRENT FINDINGS ON THE NEPHROGENIC POTENTIAL OF AMNIOTIC FLUID STEM (AFS) CELLS AND THEIR PUTATIVE IMPLICATIONS FOR CLINICAL APPLICATIONS AND FOR STUDIES ON SPECIFIC HUMAN GENETIC DISEASES. RESULTS: SINCE THEIR DISCOVERY IN 2003, AFS CELLS HAVE BEEN SHOWN TO BE PLURIPOTENT WITH THE POTENTIAL TO FORM EMBRYOID BODIES. COMPARED TO ADULT STEM CELLS, INDUCED PLURIPOTENT STEM CELLS OR EMBRYONIC STEM CELLS, AFS CELLS HARBOUR A VARIETY OF ADVANTAGES, SUCH AS THEIR HIGH DIFFERENTIATION AND PROLIFERATIVE POTENTIAL, NO NEED FOR ECTOPIC INDUCTION OF PLURIPOTENCY AND NO SOMATIC MUTATIONS AND EPIGENETIC MEMORY OF SOURCE CELLS, AND NO TUMOURIGENIC POTENTIAL AND ASSOCIATED ETHICAL CONTROVERSIES, RESPECTIVELY. CONCLUSIONS: RECENTLY, THE RESULTS OF DIFFERENT INDEPENDENT STUDIES PROVIDED EVIDENCE THAT AFS CELLS COULD INDEED BE A POWERFUL TOOL FOR RENAL REGENERATIVE MEDICINE. 2012 12 1449 28 DIRECT LINEAGE REPROGRAMMING FOR INDUCED KERATINOCYTE STEM CELLS: A POTENTIAL APPROACH FOR SKIN REPAIR. SEVERE TRAUMA OR CHRONIC WOUNDS CAN DEPLETE THE KERATINOCYTE STEM CELLS (KSCS) PRESENT IN THE EPIDERMAL BASAL LAYER OR INHIBIT THEIR MIGRATION LEADING TO COMPROMISED WOUND HEALING. SUPPLEMENTING KSCS IS THE KEY TO SOLUTION WHILE LINEAGE REPROGRAMMING PROVIDES A NEW APPROACH TO ACQUIRING KSCS. THROUGH DIRECT LINEAGE REPROGRAMMING, INDUCED KSCS (IKSCS) CAN BE PRODUCED FROM SOMATIC CELLS, WHICH EXHIBIT GREAT APPLICATION POTENTIAL. TWO STRATEGIES ARE CURRENTLY BEING USED TO DIRECTLY GENERATE IKSCS, LINEAGE TRANSCRIPTION FACTOR (TF)-MEDIATED AND PLURIPOTENCY FACTORS-MEDIATED. THIS REVIEW FOCUSES ON LINEAGE TF-MEDIATED DIRECT REPROGRAMMING AND DESCRIBES THE CONVERSION PROCESS ALONG WITH THE UNDERLYING EPIGENETIC MECHANISMS. IT ALSO DISCUSSES OTHER POTENTIAL INDUCTION STRATEGIES TO GENERATE IKSCS AND CHALLENGES ASSOCIATED WITH IN SITU REPROGRAMMING FOR SKIN REPAIR. 2023 13 2693 32 EVOLUTION, KIDNEY DEVELOPMENT, AND CHRONIC KIDNEY DISEASE. THERE IS A GLOBAL EPIDEMIC OF CHRONIC KIDNEY DISEASE (CKD) CHARACTERIZED BY A PROGRESSIVE LOSS OF NEPHRONS, ASCRIBED IN LARGE PART TO A RISING INCIDENCE OF HYPERTENSION, METABOLIC SYNDROME, AND TYPE 2 DIABETES MELLITUS. THERE IS A TEN-FOLD VARIATION IN NEPHRON NUMBER AT BIRTH IN THE GENERAL POPULATION, AND A 50% OVERALL DECREASE IN NEPHRON NUMBER IN THE LAST DECADES OF LIFE. THE VICIOUS CYCLE OF NEPHRON LOSS STIMULATING HYPERTROPHY BY REMAINING NEPHRONS AND RESULTING IN GLOMERULOSCLEROSIS HAS BEEN REGARDED AS MALADAPTIVE, AND ONLY PARTIALLY RESPONSIVE TO ANGIOTENSIN INHIBITION. ADVANCES OVER THE PAST CENTURY IN KIDNEY PHYSIOLOGY, GENETICS, AND DEVELOPMENT HAVE ELUCIDATED MANY ASPECTS OF NEPHRON FORMATION, STRUCTURE AND FUNCTION. PARALLEL ADVANCES HAVE BEEN ACHIEVED IN EVOLUTIONARY BIOLOGY, WITH THE EMERGENCE OF EVOLUTIONARY MEDICINE, A DISCIPLINE THAT PROMISES TO PROVIDE NEW INSIGHT INTO THE TREATMENT OF CHRONIC DISEASE. THIS REVIEW PROVIDES A FRAMEWORK FOR UNDERSTANDING THE ORIGINS OF CONTEMPORARY DEVELOPMENTAL NEPHROLOGY, AND RECENT PROGRESS IN EVOLUTIONARY BIOLOGY. THE ESTABLISHMENT OF EVOLUTIONARY DEVELOPMENTAL BIOLOGY (EVO-DEVO), ECOLOGICAL DEVELOPMENTAL BIOLOGY (ECO-DEVO), AND DEVELOPMENTAL ORIGINS OF HEALTH AND DISEASE (DOHAD) FOLLOWED THE DISCOVERY OF THE HOX GENE FAMILY, THE RECOGNITION OF THE CONTRIBUTION OF CUMULATIVE ENVIRONMENTAL STRESSORS TO THE CHANGING PHENOTYPE OVER THE LIFE CYCLE, AND MECHANISMS OF EPIGENETIC REGULATION. THE MATURATION OF EVOLUTIONARY MEDICINE HAS CONTRIBUTED TO NEW INVESTIGATIVE APPROACHES TO CARDIOVASCULAR DISEASE, CANCER, AND INFECTIOUS DISEASE, AND PROMISES THE SAME FOR CKD. BY INCORPORATING THESE PRINCIPLES, DEVELOPMENTAL NEPHROLOGY IS IDEALLY POSITIONED TO ANSWER IMPORTANT QUESTIONS REGARDING THE FATE OF NEPHRONS FROM EMBRYO THROUGH SENESCENCE. 2019 14 2786 27 EZH2 RESTRICTS THE SMOOTH MUSCLE LINEAGE DURING MOUSE LUNG MESOTHELIAL DEVELOPMENT. DURING DEVELOPMENT, THE LUNG MESODERM GENERATES A VARIETY OF CELL LINEAGES, INCLUDING AIRWAY AND VASCULAR SMOOTH MUSCLE. EPIGENETIC CHANGES IN ADULT LUNG MESODERMAL LINEAGES ARE THOUGHT TO CONTRIBUTE TOWARDS DISEASES SUCH AS IDIOPATHIC PULMONARY FIBROSIS AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE, ALTHOUGH THE FACTORS THAT REGULATE EARLY LUNG MESODERM DEVELOPMENT ARE UNKNOWN. WE SHOW IN MOUSE THAT THE PRC2 COMPONENT EZH2 IS REQUIRED TO RESTRICT SMOOTH MUSCLE DIFFERENTIATION IN THE DEVELOPING LUNG MESOTHELIUM. MESODERMAL LOSS OF EZH2 LEADS TO THE FORMATION OF ECTOPIC SMOOTH MUSCLE IN THE SUBMESOTHELIAL REGION OF THE DEVELOPING LUNG MESODERM. LOSS OF EZH2 SPECIFICALLY IN THE DEVELOPING MESOTHELIUM REVEALS A MESOTHELIAL CELL-AUTONOMOUS ROLE FOR EZH2 IN REPRESSION OF THE SMOOTH MUSCLE DIFFERENTIATION PROGRAM. LOSS OF EZH2 DEREPRESSES EXPRESSION OF MYOCARDIN AND TBX18, WHICH ARE IMPORTANT REGULATORS OF SMOOTH MUSCLE DIFFERENTIATION FROM THE MESOTHELIUM AND RELATED CELL LINEAGES. TOGETHER, THESE FINDINGS UNCOVER AN EZH2-DEPENDENT MECHANISM TO RESTRICT THE SMOOTH MUSCLE GENE EXPRESSION PROGRAM IN THE DEVELOPING MESOTHELIUM AND ALLOW APPROPRIATE CELL FATE DECISIONS TO OCCUR IN THIS MULTIPOTENT MESODERM LINEAGE. 2016 15 2592 29 EPIGENETICS OF RENAL DEVELOPMENT AND DISEASE. AN UNDERSTANDING OF EPIGENETICS IS INDISPENSABLE TO OUR UNDERSTANDING OF GENE REGULATION UNDER NORMAL AND PATHOLOGICAL STATES. THIS KNOWLEDGE WILL HELP WITH DESIGNING BETTER THERAPEUTIC APPROACHES IN REGENERATIVE TISSUE MEDICINE. EPIGENETICS ALLOWS US TO PARSE OUT THE MECHANISMS BY WHICH TRANSCRIPTIONAL REGULATORS GAIN ACCESS TO SPECIFIC GENE LOCI THEREBY IMPRINTING EPIGENETIC INFORMATION AFFECTING CHROMATIN FUNCTION. THIS EPIGENETIC MEMORY FORMS THE BASIS OF CELL LINEAGE SPECIFICATION IN MULTICELLULAR ORGANISMS. POST-TRANSLATIONAL MODIFICATIONS TO DNA AND HISTONES IN THE NUCLEOSOME CORE FORM CHARACTERISTIC EPIGENETIC CODES WHICH ARE DISTINCT FOR SELF-RENEWING AND PRIMED PROGENITOR CELL POPULATIONS. STUDIES OF CHROMATIN MODIFIERS AND MODIFICATIONS IN RENAL DEVELOPMENT AND DISEASE HAVE BEEN GAINING MOMENTUM. BOTH CONGENITAL AND ADULT RENAL DISEASES HAVE A GENE-ENVIRONMENT COMPONENT, WHICH INVOLVES ALTERATIONS TO THE EPIGENETIC INFORMATION IMPRINTED DURING DEVELOPMENT. THIS EPIGENETIC MEMORY MUST BE CHARACTERIZED TO ESTABLISH OPTIMAL TREATMENT OF BOTH ACUTE AND CHRONIC RENAL DISEASES. 2016 16 4674 32 NEW INSIGHTS INTO THE ROLE AND MECHANISM OF PARTIAL EPITHELIAL-MESENCHYMAL TRANSITION IN KIDNEY FIBROSIS. EPITHELIAL-MESENCHYMAL TRANSITION (EMT) IS DESCRIBED AS THE PROCESS IN WHICH INJURED RENAL TUBULAR EPITHELIAL CELLS UNDERGO A PHENOTYPE CHANGE, ACQUIRING MESENCHYMAL CHARACTERISTICS AND MORPHING INTO FIBROBLASTS. INITIALLY, IT WAS WIDELY THOUGHT OF AS A CRITICAL MECHANISM OF FIBROGENESIS UNDERLYING CHRONIC KIDNEY DISEASE. HOWEVER, EVIDENCE THAT RENAL TUBULAR EPITHELIAL CELLS CAN CROSS THE BASEMENT MEMBRANE AND BECOME FIBROBLASTS IN THE RENAL INTERSTITIUM IS RARE, LEADING TO DEBATE ABOUT THE EXISTENCE OF EMT. RECENT RESEARCH HAS DEMONSTRATED THAT AFTER INJURY, RENAL TUBULAR EPITHELIAL CELLS ACQUIRE MESENCHYMAL CHARACTERISTICS AND THE ABILITY TO PRODUCE A VARIETY OF PROFIBROTIC FACTORS AND CYTOKINES, BUT REMAIN ATTACHED TO THE BASEMENT MEMBRANE. ON THIS BASIS, A NEW CONCEPT OF "PARTIAL EPITHELIAL-MESENCHYMAL TRANSITION (PEMT)" WAS PROPOSED TO EXPLAIN THE CONTRIBUTION OF RENAL EPITHELIAL CELLS TO RENAL FIBROGENESIS. IN THIS REVIEW, WE DISCUSS THE CONCEPT OF PEMT AND THE MOST RECENT FINDINGS RELATED TO THIS PROCESS, INCLUDING CELL CYCLE ARREST, METABOLIC ALTERNATION OF EPITHELIAL CELLS, INFILTRATION OF IMMUNE CELLS, EPIGENETIC REGULATION AS WELL AS THE NOVEL SIGNALING PATHWAYS THAT MEDIATE THIS DISTURBED EPITHELIAL-MESENCHYMAL COMMUNICATION. A DEEPER UNDERSTANDING OF THE ROLE AND THE MECHANISM OF PEMT MAY HELP IN DEVELOPING NOVEL THERAPIES TO PREVENT AND HALT FIBROSIS IN KIDNEY DISEASE. 2020 17 1366 23 DEVELOPMENTAL ORIGINS OF CHRONIC KIDNEY DISEASE: SHOULD WE FOCUS ON EARLY LIFE? CHRONIC KIDNEY DISEASE (CKD) IS BECOMING A GLOBAL BURDEN, DESPITE RECENT ADVANCES IN MANAGEMENT. CKD CAN BEGIN IN EARLY LIFE BY SO-CALLED "DEVELOPMENTAL PROGRAMMING" OR "DEVELOPMENTAL ORIGINS OF HEALTH AND DISEASE" (DOHAD). EARLY-LIFE INSULTS CAUSE STRUCTURAL AND FUNCTIONAL CHANGES IN THE DEVELOPING KIDNEY, WHICH IS CALLED RENAL PROGRAMMING. EPIDEMIOLOGICAL AND EXPERIMENTAL EVIDENCE SUPPORTS THE PROPOSITION THAT EARLY-LIFE ADVERSE EVENTS LEAD TO RENAL PROGRAMMING AND MAKE SUBJECTS VULNERABLE TO DEVELOPING CKD AND ITS COMORBIDITIES IN LATER LIFE. IN ADDITION TO LOW NEPHRON ENDOWMENT, SEVERAL MECHANISMS HAVE BEEN PROPOSED FOR RENAL PROGRAMMING. THE DOHAD CONCEPT OPENS A NEW WINDOW TO OFFSET THE PROGRAMMING PROCESS IN EARLY LIFE TO PREVENT THE DEVELOPMENT OF ADULT KIDNEY DISEASE, NAMELY REPROGRAMMING. HERE, WE REVIEW THE KEY THEMES ON THE DEVELOPMENTAL ORIGINS OF CKD. WE HAVE PARTICULARLY FOCUSED ON THE FOLLOWING AREAS: EVIDENCE FROM HUMAN STUDIES SUPPORT FETAL PROGRAMMING OF KIDNEY DISEASE; INSIGHT FROM ANIMAL MODELS OF RENAL PROGRAMMING; HYPOTHETICAL MECHANISMS OF RENAL PROGRAMMING; ALTERATIONS OF RENAL TRANSCRIPTOME IN RESPONSE TO EARLY-LIFE INSULTS; AND THE APPLICATION OF REPROGRAMMING INTERVENTIONS TO PREVENT THE PROGRAMMING OF KIDNEY DISEASE. 2017 18 5329 36 PURINERGIC SIGNALING IN THE LUMEN OF A NORMAL NEPHRON AND IN REMODELED PKD ENCAPSULATED CYSTS. THE NEPHRON IS THE FUNCTIONAL UNIT OF THE KIDNEY. BLOOD AND PLASMA ARE CONTINUALLY FILTERED WITHIN THE GLOMERULI THAT BEGIN EACH NEPHRON. ADENOSINE 5' TRIPHOSPHATE (ATP) AND ITS METABOLITES ARE FREELY FILTERED BY EACH GLOMERULUS AND ENTER THE LUMEN OF EACH NEPHRON BEGINNING AT THE PROXIMAL CONVOLUTED TUBULE (PCT). FLOW RATE, OSMOLALITY, AND OTHER MECHANICAL OR CHEMICAL STIMULI FOR ATP SECRETION ARE PRESENT IN EACH NEPHRON SEGMENT. THESE ATP-RELEASE STIMULI ARE ALSO DIFFERENT IN EACH NEPHRON SEGMENT DUE TO WATER OR SALT PERMEABILITY OR IMPERMEABILITY ALONG DIFFERENT LUMINAL MEMBRANES OF THE CELLS THAT LINE EACH NEPHRON SEGMENT. EACH OF THE ABOVE STIMULI CAN TRIGGER ADDITIONAL ATP RELEASE INTO THE LUMEN OF A NEPHRON SEGMENT. EACH NEPHRON-LINING EPITHELIAL CELL IS A POTENTIAL SOURCE OF SECRETED ATP. TOGETHER WITH FILTERED ATP AND ITS METABOLITES DERIVED FROM THE GLOMERULUS, SECRETED ATP AND ADENOSINE DERIVED FROM CELLS ALONG THE NEPHRON ARE LIKELY THE PRINCIPAL TWO OF SEVERAL NUCLEOTIDE AND NUCLEOSIDE CANDIDATES FOR RENAL AUTOCRINE AND PARACRINE LIGANDS WITHIN THE TUBULAR FLUID OF THE NEPHRON. THIS MINIREVIEW DISCUSSES THE FIRST PRINCIPLES OF PURINERGIC SIGNALING AS THEY RELATE TO THE NEPHRON AND THE URINARY BLADDER. THE REVIEW DISCUSSES HOW THE LUMEN OF A RENAL TUBULE PRESENTS AN IDEAL PURINERGIC SIGNALING MICROENVIRONMENT. THE REVIEW ALSO ILLUSTRATES HOW REMODELED AND ENCAPSULATED CYSTS IN AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE (ADPKD) AND REMODELED PSEUDOCYSTS IN AUTOSOMAL RECESSIVE PKD (ARPKD) OF THE RENAL COLLECTING DUCT LIKELY CREATE AN EVEN MORE IDEAL MICROENVIRONMENT FOR PURINERGIC SIGNALING. ONCE TRAPPED IN THESE CLOSED MICROENVIRONMENTS, PURINERGIC SIGNALING BECOMES CHRONIC AND LIKELY PLAYS A SIGNIFICANT EPIGENETIC AND DETRIMENTAL ROLE IN THE SECONDARY PROGRESSION OF PKD, ONCE THE REMODELING OF THE RENAL TISSUE HAS BEGUN. IN PKD CYSTIC MICROENVIRONMENTS, WE ARGUE THAT NORMAL PURINERGIC SIGNALING WITHIN THE LUMEN OF THE NEPHRON PROVIDES DETRIMENTAL ACCELERATION OF ADPKD ONCE REMODELING IS COMPLETE. 2008 19 2555 20 EPIGENETICS IN RENAL DISEASES. WITH AGING, PREVALENCE OF OBESITY, HYPERTENSION, DIABETES AND RENAL DISEASES HAVE INCREASED GLOBALLY. OVER THE LAST TWO DECADES, THE PREVALENCE OF RENAL DISEASES HAS BEEN INTENSELY INCREASING. RENAL DISEASE AND RENAL PROGRAMMING ARE REGULATED BY EPIGENETIC MODIFICATIONS LIKE DNA METHYLATION AND HISTONE MODIFICATIONS. ENVIRONMENTAL FACTORS HAVE SIGNIFICANT ROLE IN THE PATHOPHYSIOLOGY OF RENAL DISEASE PROGRESSION. UNDERSTANDING THE POTENTIAL OF EPIGENETIC REGULATION OF GENE EXPRESSION MAY BE USEFUL IN RENAL DISEASE PROGNOSIS, DIAGNOSIS AND PROVIDES NOVEL THERAPEUTIC MEASURES. IN A NUTSHELL, THIS CHAPTER TALKS ABOUT THE ROLE OF EPIGENETIC MECHANISMS-DNA METHYLATION, HISTONE MODIFICATION, AND NONCODING RNA IN DIFFERENT RENAL DISEASES. THESE INCLUDE DIABETIC KIDNEY DISEASE, DIABETIC NEPHROPATHY, RENAL FIBROSIS, ETC. 2023 20 2072 26 EPIGENETIC CONVERSION OF HUMAN ADULT BONE MESODERMAL STROMAL CELLS INTO NEUROECTODERMAL CELL TYPES FOR REPLACEMENT THERAPY OF NEURODEGENERATIVE DISORDERS. TISSUE-SPECIFIC STEM CELLS, SUCH AS BONE MARROW-DERIVED MESODERMAL STROMAL CELLS (MSCS), ARE THOUGHT TO BE LINEAGE RESTRICTED AND, THEREFORE, COULD ONLY BE DIFFERENTIATED INTO CELL TYPES OF THE TISSUE OF ORIGIN. SEVERAL RECENT STUDIES, HOWEVER, SUGGEST THAT THESE TYPES OF STEM CELLS MIGHT BE ABLE TO BREAK BARRIERS OF GERM LAYER COMMITMENT AND DIFFERENTIATE IN VITRO AND/OR IN VIVO INTO CELLS OF DIFFERENT TISSUES, SUCH AS NEUROECTODERMAL CELL TYPES. RECENTLY, PROTOCOLS FOR HIGH-YIELD GENERATION OF UNDIFFERENTIATED NEURAL STEM CELL (NSC)-LIKE CELLS FROM MSCS OF PRIMATE AND HUMAN ORIGIN WERE REPORTED. UNDIFFERENTIATED NSCS ARE COMMONLY USED AND ARE MORE SUITABLE FOR NEUROTRANSPLANTATION COMPARED WITH FULLY DIFFERENTIATED NEURAL CELLS, AS DIFFERENTIATED NEURAL CELLS ARE WELL KNOWN TO POORLY SURVIVE DETACHMENT AND SUBSEQUENT TRANSPLANTATION PROCEDURES. THESE HUMAN MSC-DERIVED NSC-LIKE CELLS (MSC-NSCS) GROW IN NEUROSPHERE-LIKE STRUCTURES AND EXPRESS HIGH LEVELS OF EARLY NEUROECTODERMAL MARKERS, BUT LOSE CHARACTERISTICS OF MSCS. IN THE PRESENCE OF SELECTED GROWTH FACTORS, HUMAN MSC-NSCS CAN BE DIFFERENTIATED INTO THE THREE MAIN NEURAL PHENOTYPES: ASTROGLIA, OLIGODENDROGLIA AND NEURONS. COMPARED WITH DIRECT DIFFERENTIATION OF HUMAN MSCS INTO MATURE NEURAL CELLS, THE CONVERSION STEP SEEMS TO BE ESSENTIAL TO GENERATE MATURE FUNCTIONAL NEUROECTODERMAL CELLS. THIS REVIEW DESCRIBES THE TECHNIQUES FOR THE CONVERSION OF HUMAN MSCS INTO NSCS AND SUMMARISES THE DATA ON EPIGENETIC CONVERSION OF HUMAN MSCS INTO IMMATURE NEUROECTODERMAL CELLS. THESE CELLS PROVIDE A POWERFUL TOOL FOR INVESTIGATING THE MOLECULAR MECHANISMS OF NEURAL DIFFERENTIATION, AND MIGHT SERVE AS AN AUTOLOGOUS CELL SOURCE TO TREAT ACUTE AND CHRONIC NEURODEGENERATIVE DISEASES. 2006