1 4000 156 LOSS OF HISTONE H3 K79 METHYLTRANSFERASE DOT1L FACILITATES KIDNEY FIBROSIS BY UPREGULATING ENDOTHELIN 1 THROUGH HISTONE DEACETYLASE 2. BACKGROUND: THE PROGRESSION RATE OF CKD VARIES SUBSTANTIALLY AMONG PATIENTS. THE GENETIC AND EPIGENETIC CONTRIBUTIONS THAT MODIFY HOW INDIVIDUAL PATIENTS RESPOND TO KIDNEY INJURY ARE LARGELY UNKNOWN. EMERGING EVIDENCE HAS SUGGESTED THAT HISTONE H3 K79 METHYLTRANSFERASE DOT1L HAS AN ANTIFIBROTIC EFFECT BY REPRESSING EDN1, WHICH ENCODES ENDOTHELIN 1 IN THE CONNECTING TUBULE/COLLECTING DUCT. METHODS: TO DETERMINE IF DELETION OF THE DOT1L GENE IS A GENETIC AND EPIGENETIC RISK FACTOR THROUGH REGULATING EDN1, WE STUDIED FOUR GROUPS OF MICE: WILD-TYPE MICE, CONNECTING TUBULE/COLLECTING DUCT-SPECIFIC DOT1L CONDITIONAL KNOCKOUT MICE (DOT1L(AC) ), DOT1L AND EDN1 DOUBLE-KNOCKOUT MICE (DE(AC) ), AND EDN1 CONNECTING TUBULE/COLLECTING DUCT-SPECIFIC CONDITIONAL KNOCKOUT MICE (EDN1(AC) ), UNDER THREE EXPERIMENTAL CONDITIONS (STREPTOZOTOCIN-INDUCED DIABETES, DURING NORMAL AGING, AND AFTER UNILATERAL URETERAL OBSTRUCTION). WE USED SEVERAL APPROACHES (COLOCALIZATION, GLUTATHIONE S-TRANSFERASE PULLDOWN, COIMMUNOPRECIPITATION, YEAST TWO-HYBRID, GEL SHIFT, AND CHROMATIN IMMUNOPRECIPITATION ASSAYS) TO IDENTIFY AND CONFIRM INTERACTION OF DOT1A (THE MAJOR DOT1L SPLICING VARIANT IN THE MOUSE KIDNEY) WITH HISTONE DEACETYLASE 2 (HDAC2), AS WELL AS THE FUNCTION OF THE DOT1A-HDAC2 COMPLEX IN REGULATING EDN1 TRANSCRIPTION. RESULTS: IN EACH CASE, DOT1L(AC) MICE DEVELOPED MORE PRONOUNCED KIDNEY FIBROSIS AND KIDNEY MALFUNCTION COMPARED WITH WILD-TYPE MICE. THESE DOT1L(AC) PHENOTYPES WERE AMELIORATED IN THE DOUBLE-KNOCKOUT DE(AC) MICE. THE INTERACTION BETWEEN DOT1A AND HDAC2 PREVENTS THE DOT1A-HDAC2 COMPLEX FROM ASSOCIATION WITH DNA, PROVIDING A COUNTERBALANCING MECHANISM GOVERNING EDN1 TRANSCRIPTION BY MODULATING H3 K79 DIMETHYLATION AND H3 ACETYLATION AT THE EDN1 PROMOTER. CONCLUSIONS: OUR STUDY CONFIRMS DOT1L TO BE A GENETIC AND EPIGENETIC MODIFIER OF KIDNEY FIBROSIS, REVEALS A NEW MECHANISM REGULATING EDN1 TRANSCRIPTION BY DOT1A AND HDAC2, AND REINFORCES ENDOTHELIN 1 AS A THERAPEUTIC TARGET OF KIDNEY FIBROSIS. 2020 2 3824 31 INVESTIGATING THE EPIGENETIC EFFECTS OF A PROTOTYPE SMOKE-DERIVED CARCINOGEN IN HUMAN CELLS. GLOBAL LOSS OF DNA METHYLATION AND LOCUS/GENE-SPECIFIC GAIN OF DNA METHYLATION ARE TWO DISTINCT HALLMARKS OF CARCINOGENESIS. ABERRANT DNA METHYLATION IS IMPLICATED IN SMOKING-RELATED LUNG CANCER. IN THIS STUDY, WE HAVE COMPREHENSIVELY INVESTIGATED THE MODULATION OF DNA METHYLATION CONSEQUENT TO CHRONIC EXPOSURE TO A PROTOTYPE SMOKE-DERIVED CARCINOGEN, BENZO[A]PYRENE DIOL EPOXIDE (B[A]PDE), IN GENOMIC REGIONS OF SIGNIFICANCE IN LUNG CANCER, IN NORMAL HUMAN CELLS. WE HAVE USED A PULLDOWN ASSAY FOR ENRICHMENT OF THE CPG METHYLATED FRACTION OF CELLULAR DNA COMBINED WITH MICROARRAY PLATFORMS, FOLLOWED BY EXTENSIVE VALIDATION THROUGH CONVENTIONAL BISULFITE-BASED ANALYSIS. HERE, WE DEMONSTRATE STRIKINGLY SIMILAR PATTERNS OF DNA METHYLATION IN NON-TRANSFORMED B[A]PDE-TREATED CELLS VS CONTROL USING HIGH-THROUGHPUT MICROARRAY-BASED DNA METHYLATION PROFILING CONFIRMED BY CONVENTIONAL BISULFITE-BASED DNA METHYLATION ANALYSIS. THE ABSENCE OF ABERRANT DNA METHYLATION IN OUR MODEL SYSTEM WITHIN A TIMEFRAME THAT PRECEDES CELLULAR TRANSFORMATION SUGGESTS THAT FOLLOWING CARCINOGEN EXPOSURE, OTHER AS YET UNKNOWN FACTORS (SECONDARY TO CARCINOGEN TREATMENT) MAY HELP INITIATE GLOBAL LOSS OF DNA METHYLATION AND REGION-SPECIFIC GAIN OF DNA METHYLATION, WHICH CAN, IN TURN, CONTRIBUTE TO LUNG CANCER DEVELOPMENT. UNVEILING THE INITIATING EVENTS THAT CAUSE ABERRANT DNA METHYLATION IN LUNG CANCER HAS TREMENDOUS PUBLIC HEALTH RELEVANCE, AS IT CAN HELP DEFINE FUTURE STRATEGIES FOR EARLY DETECTION AND PREVENTION OF THIS HIGHLY LETHAL DISEASE. 2010 3 5683 29 SHORTER TELOMERE LENGTH IN PERIPHERAL BLOOD LYMPHOCYTES OF WORKERS EXPOSED TO POLYCYCLIC AROMATIC HYDROCARBONS. SHORTER TELOMERE LENGTH (TL) IN PERIPHERAL BLOOD LYMPHOCYTES (PBLS) IS PREDICTIVE OF LUNG CANCER RISK. POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) ARE ESTABLISHED LUNG CARCINOGENS THAT CAUSE CHROMOSOME INSTABILITY. WHETHER PAH EXPOSURE AND ITS MOLECULAR EFFECTS ARE LINKED WITH SHORTER TL HAS NEVER BEEN EVALUATED. IN THE PRESENT STUDY, WE INVESTIGATED THE EFFECT OF CHRONIC EXPOSURE TO PAHS ON TL MEASURED IN PBLS OF POLISH MALE NON-CURRENT SMOKING COKEOVEN WORKERS AND MATCHED CONTROLS. PAH EXPOSURE AND MOLECULAR EFFECTS WERE CHARACTERIZED USING MEASURES OF INTERNAL DOSE (URINARY 1-PYRENOL), EFFECTIVE DOSE [ANTI-BENZO[A]PYRENE DIOLEPOXIDE (ANTI-BPDE)-DNA ADDUCT], GENETIC INSTABILITY (MICRONUCLEI, MN) AND DNA METHYLATION [P53 PROMOTER AND ALU AND LONG INTERSPERSED NUCLEAR ELEMENT-1 (LINE-1) REPETITIVE ELEMENTS, AS SURROGATE MEASURES OF GLOBAL METHYLATION] IN PBLS. TL WAS MEASURED BY REAL-TIME POLYMERASE CHAIN REACTION. COKEOVEN WORKERS WERE HEAVILY EXPOSED TO PAHS (79% EXCEEDED THE URINARY 1-PYRENOL BIOLOGICAL EXPOSURE INDEX) AND EXHIBITED LOWER TL (P = 0.038) THAN CONTROLS, AS WELL AS HIGHER LEVELS OF GENETIC AND CHROMOSOMAL ALTERATIONS [I.E. ANTI-BPDE-DNA ADDUCT AND MN (P < 0.0001)] AND EPIGENETIC CHANGES [I.E. P53 GENE-SPECIFIC PROMOTER AND GLOBAL METHYLATION (P