1 6570 129 TRANSPOSABLE ELEMENTS AND THEIR POTENTIAL ROLE IN COMPLEX LUNG DISORDER. TRANSPOSABLE ELEMENTS (TES) ARE A CLASS OF MOBILE GENETIC ELEMENTS (MGES) THAT WERE LONG REGARDED AS JUNK DNA, WHICH MAKE UP APPROXIMATELY 45% OF THE GENOME. ALTHOUGH MOST OF THESE ELEMENTS ARE RENDERED INACTIVE BY MUTATIONS AND OTHER GENE SILENCING MECHANISMS, TES SUCH AS LONG INTERSPERSED NUCLEAR ELEMENTS (LINES) ARE STILL ACTIVE AND TRANSLOCATE WITHIN THE GENOME. DURING TRANSPOSITION, THEY MAY CREATE LESIONS IN THE GENOME, THEREBY ACTING AS EPIGENETIC MODIFIERS. APPROXIMATELY 65 DISEASE-CAUSING LINE INSERTION EVENTS HAVE BEEN REPORTED THUS FAR; HOWEVER, ANY POSSIBLE ROLE OF TES IN COMPLEX DISORDERS IS NOT WELL ESTABLISHED. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) IS ONE SUCH COMPLEX DISEASE THAT IS PRIMARILY CAUSED BY CIGARETTE SMOKING. ALTHOUGH THE EXACT MOLECULAR MECHANISM UNDERLYING COPD REMAINS UNCLEAR, OXIDATIVE STRESS IS THOUGHT TO BE THE MAIN FACTOR IN THE PATHOGENESIS OF COPD. IN THIS REVIEW, WE EXPLORE THE POTENTIAL ROLE OF OXIDATIVE STRESS IN EPIGENETIC ACTIVATION OF TES SUCH AS LINES AND THE SUBSEQUENT CASCADE OF MOLECULAR DAMAGE. RECENT ADVANCEMENTS IN SEQUENCING AND COMPUTATION HAVE EASED THE IDENTIFICATION OF MOBILE ELEMENTS. THEREFORE, A COMPARATIVE STUDY ON THE ACTIVITY OF THESE ELEMENTS AND MARKERS FOR GENOME INSTABILITY WOULD GIVE MORE INSIGHT ON THE RELATIONSHIP BETWEEN MGES AND COMPLEX DISORDER SUCH AS COPD. 2013 2 6397 27 THE ROLE OF TRANSPOSABLE ELEMENTS IN AGING AND CANCER. TRANSPOSABLE ELEMENTS (TES) CONSTITUTE A LARGE PORTION OF THE HUMAN GENOME. VARIOUS MECHANISMS AT THE TRANSCRIPTION AND POST-TRANSCRIPTION LEVELS DEVELOPED TO SUPPRESS TE ACTIVITY IN HEALTHY CONDITIONS. HOWEVER, A GROWING BODY OF EVIDENCE SUGGESTS THAT TE DYSREGULATION IS INVOLVED IN VARIOUS HUMAN DISEASES, INCLUDING AGE-RELATED DISEASES AND CANCER. IN THIS REVIEW, WE EXPLAINED HOW SENSING TES BY THE IMMUNE SYSTEM COULD INDUCE INNATE IMMUNE RESPONSES, CHRONIC INFLAMMATION, AND FOLLOWING AGE-RELATED DISEASES. WE ALSO NOTED THAT INFLAMMAGEING AND EXOGENOUS CARCINOGENS COULD TRIGGER THE UPREGULATION OF TES IN PRECANCEROUS CELLS. INCREASED INFLAMMATION COULD ENHANCE EPIGENETIC PLASTICITY AND UPREGULATION OF EARLY DEVELOPMENTAL TES, WHICH REWIRES THE TRANSCRIPTIONAL NETWORKS AND GIFT THE SURVIVAL ADVANTAGE TO THE PRECANCEROUS CELLS. IN ADDITION, UPREGULATED TES COULD INDUCE GENOME INSTABILITY, ACTIVATION OF ONCOGENES, OR INHIBITION OF TUMOR SUPPRESSORS AND CONSEQUENT CANCER INITIATION AND PROGRESSION. SO, WE SUGGEST THAT TES COULD BE CONSIDERED THERAPEUTIC TARGETS IN AGING AND CANCER. 2023 3 3419 43 HUMAN LINE-1 RETROTRANSPOSONS: IMPACTS ON THE GENOME AND REGULATION BY HOST FACTORS. GENOME SEQUENCING REVEALED THAT NEARLY HALF OF THE HUMAN GENOME IS COMPRISED OF TRANSPOSABLE ELEMENTS. ALTHOUGH MOST OF THESE ELEMENTS HAVE BEEN RENDERED INACTIVE DUE TO MUTATIONS, FULL-LENGTH INTACT LONG INTERSPERSED ELEMENT-1 (LINE-1 OR L1) COPIES RETAIN THE ABILITY TO MOBILIZE THROUGH RNA INTERMEDIATES BY A SO-CALLED "COPY-AND-PASTE" MECHANISM, TERMED RETROTRANSPOSITION. L1 IS THE ONLY KNOWN AUTONOMOUS MOBILE GENETIC ELEMENT IN THE GENOME, AND ITS RETROTRANSPOSITION CONTRIBUTES TO INTER- OR INTRA-INDIVIDUAL GENETIC VARIATION WITHIN THE HUMAN POPULATION. HOWEVER, L1 RETROTRANSPOSITION ALSO POSES A THREAT TO GENOME INTEGRITY DUE TO GENE DISRUPTION AND CHROMOSOMAL INSTABILITY. MOREOVER, RECENT STUDIES SUGGEST THAT ABERRANT L1 EXPRESSION CAN IMPACT HUMAN HEALTH BY CAUSING DISEASES SUCH AS CANCER AND CHRONIC INFLAMMATION THAT MIGHT LEAD TO AUTOIMMUNE DISORDERS. TO COUNTERACT THESE ADVERSE EFFECTS, THE HOST CELLS HAVE EVOLVED MULTIPLE LAYERS OF DEFENSE MECHANISMS AT THE EPIGENETIC, RNA AND PROTEIN LEVELS. INTRIGUINGLY, SEVERAL HOST FACTORS HAVE ALSO BEEN REPORTED TO FACILITATE L1 RETROTRANSPOSITION, SUGGESTING THAT THERE IS COMPETITION BETWEEN NEGATIVE AND POSITIVE REGULATION OF L1 BY HOST FACTORS. HERE, WE SUMMARIZE THE KNOWN HOST PROTEINS THAT REGULATE L1 ACTIVITY AT DIFFERENT STAGES OF THE REPLICATION CYCLE AND DISCUSS HOW THESE FACTORS MODULATE DISEASE-ASSOCIATED PHENOTYPES CAUSED BY L1. 2022 4 857 31 CHROMATIN ARCHITECTURE REVEALS CELL TYPE-SPECIFIC TARGET GENES FOR KIDNEY DISEASE RISK VARIANTS. BACKGROUND: CELL TYPE-SPECIFIC TRANSCRIPTIONAL PROGRAMMING RESULTS FROM THE COMBINATORIAL INTERPLAY BETWEEN THE REPERTOIRE OF ACTIVE REGULATORY ELEMENTS. DISEASE-ASSOCIATED VARIANTS DISRUPT SUCH PROGRAMMING, LEADING TO ALTERED EXPRESSION OF DOWNSTREAM REGULATED GENES AND THE ONSET OF PATHOLOGICAL STATES. HOWEVER, DUE TO THE NON-LINEAR REGULATORY PROPERTIES OF NON-CODING ELEMENTS SUCH AS ENHANCERS, WHICH CAN ACTIVATE TRANSCRIPTION AT LONG DISTANCES AND IN A NON-DIRECTIONAL WAY, THE IDENTIFICATION OF CAUSAL VARIANTS AND THEIR TARGET GENES REMAINS CHALLENGING. HERE, WE PROVIDE A MULTI-OMICS ANALYSIS TO IDENTIFY REGULATORY ELEMENTS ASSOCIATED WITH FUNCTIONAL KIDNEY DISEASE VARIANTS, AND DOWNSTREAM REGULATED GENES. RESULTS: IN ORDER TO UNDERSTAND THE GENETIC RISK OF KIDNEY DISEASES, WE GENERATED A COMPREHENSIVE DATASET OF THE CHROMATIN LANDSCAPE OF HUMAN KIDNEY TUBULE CELLS, INCLUDING TRANSCRIPTION-CENTERED 3D CHROMATIN ORGANIZATION, HISTONE MODIFICATIONS DISTRIBUTION AND TRANSCRIPTOME WITH HICHIP, CHIP-SEQ AND RNA-SEQ. WE IDENTIFIED GENOME-WIDE FUNCTIONAL ELEMENTS AND THOUSANDS OF INTERACTIONS BETWEEN THE DISTAL ELEMENTS AND TARGET GENES. THE RESULTS REVEALED THAT RISK VARIANTS FOR RENAL TUMOR AND CHRONIC KIDNEY DISEASE WERE ENRICHED IN KIDNEY TUBULE CELLS. WE FURTHER PINPOINTED THE TARGET GENES FOR THE VARIANTS AND VALIDATED TWO TARGET GENES BY CRISPR/CAS9 GENOME EDITING TECHNIQUES IN ZEBRAFISH, DEMONSTRATING THAT SLC34A1 AND MTX1 WERE INDISPENSABLE GENES TO MAINTAIN KIDNEY FUNCTION. CONCLUSIONS: OUR RESULTS PROVIDE A VALUABLE MULTI-OMICS RESOURCE ON THE CHROMATIN LANDSCAPE OF HUMAN KIDNEY TUBULE CELLS AND ESTABLISH A BIOINFORMATIC PIPELINE IN DISSECTING FUNCTIONS OF KIDNEY DISEASE-ASSOCIATED VARIANTS BASED ON CELL TYPE-SPECIFIC EPIGENOME. 2021 5 6752 39 WIDESPREAD EXONIZATION OF TRANSPOSABLE ELEMENTS IN HUMAN CODING SEQUENCES IS ASSOCIATED WITH EPIGENETIC REGULATION OF TRANSCRIPTION. TRANSPOSABLE ELEMENTS (TES) HAVE LONG BEEN REGARDED AS SELFISH OR JUNK DNA HAVING LITTLE OR NO ROLE IN THE REGULATION OR FUNCTIONING OF THE HUMAN GENOME. HOWEVER, OVER THE PAST SEVERAL YEARS THIS VIEW CAME TO BE CHALLENGED AS SEVERAL STUDIES PROVIDED ANECDOTAL AS WELL AS GLOBAL EVIDENCE FOR THE CONTRIBUTION OF TES TO THE REGULATORY AND CODING NEEDS OF HUMAN GENES. IN THIS STUDY, WE EXPLORED THE INCORPORATION AND EPIGENETIC REGULATION OF CODING SEQUENCES DONATED BY TES USING GENE EXPRESSION AND OTHER ANCILLARY GENOMICS DATA FROM TWO HUMAN HEMATOPOIETIC CELL-LINES: GM12878 (A LYMPHOBLASTOID CELL LINE) AND K562 (A CHRONIC MYELOGENOUS LEUKEMIA CELL LINE). IN EACH CELL LINE, WE FOUND SEVERAL THOUSAND INSTANCES OF TES DONATING CODING SEQUENCES TO HUMAN GENES. WE COMPARED THE TRANSCRIPTOME ASSEMBLY OF THE RNA SEQUENCING (RNA-SEQ) READS WITH AND WITHOUT THE AID OF A REFERENCE TRANSCRIPTOME AND FOUND THAT THE PERCENTAGE OF GENES THAT INCORPORATE TES IN THEIR CODING SEQUENCES IS SIGNIFICANTLY GREATER THAN THAT OBTAINED FROM THE REFERENCE TRANSCRIPTOME ASSEMBLIES USING REFSEQ AND GENCODE GENE MODELS. WE ALSO USED HISTONE MODIFICATIONS CHROMATIN IMMUNOPRECIPITATION SEQUENCING (CHIP-SEQ) DATA, CAP ANALYSIS OF GENE EXPRESSION (CAGE) DATA AND DNASEI HYPERSENSITIVITY SITE (DHS) DATA TO DEMONSTRATE THE EPIGENETIC REGULATION OF THE TE DERIVED CODING SEQUENCES. OUR RESULTS SUGGEST THAT TES FORM A SIGNIFICANTLY HIGHER PERCENTAGE OF CODING SEQUENCES THAN REPRESENTED IN GENE ANNOTATION DATABASES AND THESE TE DERIVED SEQUENCES ARE EPIGENETICALLY REGULATED IN ACCORDANCE WITH THEIR EXPRESSION IN THE TWO CELL TYPES. 2013 6 825 34 CHARACTERIZATION OF FUNCTIONAL TRANSPOSABLE ELEMENT ENHANCERS IN ACUTE MYELOID LEUKEMIA. TRANSPOSABLE ELEMENTS (TES) HAVE BEEN SHOWN TO HAVE IMPORTANT GENE REGULATORY FUNCTIONS AND THEIR ALTERATION COULD LEAD TO DISEASE PHENOTYPES. ACUTE MYELOID LEUKEMIA (AML) DEVELOPS AS A CONSEQUENCE OF A SERIES OF GENETIC CHANGES IN HEMATOPOIETIC PRECURSOR CELLS, INCLUDING MUTATIONS IN EPIGENETIC FACTORS. HERE, WE SET OUT TO STUDY THE GENE REGULATORY ROLE OF TES IN AML. WE FIRST EXPLORED THE EPIGENETIC LANDSCAPE OF TES IN AML PATIENTS USING ATAC-SEQ DATA. WE SHOW THAT A LARGE NUMBER OF TES IN GENERAL, AND MORE SPECIFICALLY MAMMALIAN-WIDE INTERSPERSED REPEATS (MIRS), ARE MORE ENRICHED IN AML CELLS THAN IN NORMAL BLOOD CELLS. WE OBTAINED A SIMILAR FINDING WHEN ANALYZING HISTONE MODIFICATION DATA IN AML PATIENTS. GENE ONTOLOGY ENRICHMENT ANALYSIS SHOWED THAT GENES NEAR MIRS IN OPEN CHROMATIN REGIONS ARE INVOLVED IN LEUKEMOGENESIS. TO FUNCTIONALLY VALIDATE THEIR REGULATORY ROLE, WE SELECTED 19 MIR REGIONS IN AML CELLS, AND TESTED THEM FOR ENHANCER ACTIVITY IN AN AML CELL LINE (KASUMI-1) AND A CHRONIC MYELOID LEUKEMIA (CML) CELL LINE (K562); THE RESULTS REVEALED SEVERAL MIRS TO BE FUNCTIONAL ENHANCERS. TAKEN TOGETHER, OUR RESULTS SUGGEST THAT TES ARE POTENTIALLY INVOLVED IN MYELOID LEUKEMOGENESIS AND HIGHLIGHT THESE SEQUENCES AS POTENTIAL CANDIDATES HARBORING AML-ASSOCIATED VARIATION. 2020 7 851 23 CHIP-SEQ ANALYSIS OF HUMAN CHRONIC MYELOID LEUKEMIA CELLS. MANY TRANSCRIPTION FACTORS, CHROMATIN-ASSOCIATED PROTEINS AND REGULATORY DNA ELEMENTS ARE GENETICALLY AND/OR EPIGENETICALLY ALTERED IN CANCER, INCLUDING CHRONIC MYELOID LEUKEMIA (CML). THIS LEADS TO DEREGULATION OF TRANSCRIPTION THAT IS OFTEN CAUSALLY LINKED TO THE TUMORIGENIC STATE. CHROMATIN-IMMUNOPRECIPITATION COUPLED WITH MASSIVELY PARALLEL DNA SEQUENCING (CHIP-SEQ) IS THE KEY TECHNOLOGY TO STUDY TRANSCRIPTION AS IT ALLOWS IN VIVO WHOLE-GENOME MAPPING OF EPIGENETIC MODIFICATIONS AND INTERACTIONS OF PROTEINS WITH DNA OR CHROMATIN. HOWEVER, NUMEROUS DNA/CHROMATIN-BINDING PROTEINS, INCLUDING EZH2, REMAIN DIFFICULT TO "CHIP," THUS YIELDING GENOME-WIDE BINDING MAPS OF ONLY SUBOPTIMAL QUALITY. HERE, WE DESCRIBE A CHIP-SEQ PROTOCOL OPTIMIZED FOR HIGH-QUALITY PROTEIN-GENOME BINDING MAPS THAT HAVE PROVEN ESPECIALLY USEFUL FOR STUDYING DIFFICULT TO 'CHIP' TRANSCRIPTION REGULATORY FACTORS IN CHRONIC MYELOID LEUKEMIA (CML) AND RELATED MALIGNANCIES. 2016 8 1562 32 DNA METHYLATION OF ENHANCER ELEMENTS IN MYELOID NEOPLASMS: THINK OUTSIDE THE PROMOTERS? GENE REGULATION THROUGH DNA METHYLATION IS A WELL DESCRIBED PHENOMENON THAT HAS A PROMINENT ROLE IN PHYSIOLOGICAL AND PATHOLOGICAL CELL-STATES. THIS EPIGENETIC MODIFICATION IS USUALLY GROUPED IN REGIONS DENOMINATED CPG ISLANDS, WHICH FREQUENTLY CO-LOCALIZE WITH GENE PROMOTERS, SILENCING THE TRANSCRIPTION OF THOSE GENES. RECENT GENOME-WIDE DNA METHYLATION STUDIES HAVE CHALLENGED THIS PARADIGM, DEMONSTRATING THAT DNA METHYLATION OF REGULATORY REGIONS OUTSIDE PROMOTERS IS ABLE TO INFLUENCE CELL-TYPE SPECIFIC GENE EXPRESSION PROGRAMS UNDER PHYSIOLOGIC OR PATHOLOGIC CONDITIONS. COUPLING GENOME-WIDE DNA METHYLATION ASSAYS WITH HISTONE MARK ANNOTATION HAS ALLOWED FOR THE IDENTIFICATION OF SPECIFIC EPIGENOMIC CHANGES THAT AFFECT ENHANCER REGULATORY REGIONS, REVEALING AN ADDITIONAL LAYER OF COMPLEXITY TO THE EPIGENETIC REGULATION OF GENE EXPRESSION. IN THIS REVIEW, WE SUMMARIZE THE NOVEL EVIDENCE FOR THE MOLECULAR AND BIOLOGICAL REGULATION OF DNA METHYLATION IN ENHANCER REGIONS AND THE DYNAMISM OF THESE CHANGES CONTRIBUTING TO THE FINE-TUNING OF GENE EXPRESSION. WE ALSO ANALYZE THE CONTRIBUTION OF ENHANCER DNA METHYLATION ON THE EXPRESSION OF RELEVANT GENES IN ACUTE MYELOID LEUKEMIA AND CHRONIC MYELOPROLIFERATIVE NEOPLASMS. THE CHARACTERIZATION OF THE ABERRANT ENHANCER DNA METHYLATION PROVIDES NOT ONLY A NOVEL PATHOGENIC MECHANISM FOR DIFFERENT TUMORS BUT ALSO HIGHLIGHTS NOVEL POTENTIAL THERAPEUTIC TARGETS FOR MYELOID DERIVED NEOPLASMS. 2019 9 2050 29 EPIGENETIC COMPONENTS OF MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME UNCOVER POTENTIAL TRANSPOSABLE ELEMENT ACTIVATION. PURPOSE: STUDIES TO DETERMINE EPIGENETIC CHANGES ASSOCIATED WITH MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME (ME/CFS) REMAIN SCARCE; HOWEVER, CURRENT EVIDENCE CLEARLY SHOWS THAT METHYLATION PATTERNS OF GENOMIC DNA AND NONCODING RNA PROFILES OF IMMUNE CELLS DIFFER BETWEEN PATIENTS AND HEALTHY SUBJECTS, SUGGESTING AN ACTIVE ROLE OF THESE EPIGENETIC MECHANISMS IN THE DISEASE. THE PRESENT STUDY COMPARES AND CONTRASTS THE AVAILABLE ME/CFS EPIGENETIC DATA IN AN EFFORT TO EVIDENCE OVERLAPPING PATHWAYS CAPABLE OF EXPLAINING AT LEAST SOME OF THE DYSFUNCTIONAL IMMUNE PARAMETERS LINKED TO THIS DISEASE. METHODS: A SYSTEMATIC SEARCH OF THE LITERATURE EVALUATING THE ME/CFS EPIGENOME LANDSCAPE WAS PERFORMED FOLLOWING THE PREFERRED REPORTING ITEMS FOR SYSTEMATIC REVIEWS AND META-ANALYSES CRITERIA. DIFFERENTIAL DNA METHYLATION AND NONCODING RNA DIFFERENTIAL EXPRESSION PATTERNS ASSOCIATED WITH ME/CFS WERE USED TO SCREEN FOR THE PRESENCE OF TRANSPOSABLE ELEMENTS USING THE DFAM BROWSER, A SEARCH PROGRAM NURTURED WITH THE REPBASE REPETITIVE SEQUENCE DATABASE AND THE REPEATMASKER ANNOTATION TOOL. FINDINGS: UNEXPECTEDLY, PARTICULAR ASSOCIATIONS OF TRANSPOSABLE ELEMENTS AND ME/CFS EPIGENETIC HALLMARKS WERE UNCOVERED. A MODEL FOR THE DISEASE EMERGED INVOLVING TRANSCRIPTIONAL INDUCTION OF ENDOGENOUS DORMANT TRANSPOSONS AND STRUCTURED CELLULAR RNA INTERACTIONS, TRIGGERING THE ACTIVATION OF THE INNATE IMMUNE SYSTEM WITHOUT A CONCOMITANT ACTIVE INFECTION. IMPLICATIONS: REPETITIVE SEQUENCE FILTERS (IE, REPEATMASKER) SHOULD BE AVOIDED WHEN ANALYZING TRANSCRIPTOMIC DATA TO ASSESS THE POTENTIAL PARTICIPATION OF REPETITIVE SEQUENCES ("JUNK REPETITIVE DNA"), REPRESENTING >45% OF THE HUMAN GENOME, IN THE ONSET AND EVOLUTION OF ME/CFS. IN ADDITION, TRANSPOSABLE ELEMENT SCREENINGS AIMED AT DESIGNING COST-EFFECTIVE, FOCUSED EMPIRICAL ASSAYS THAT CAN CONFIRM OR DISPROVE THE SUSPECTED INVOLVEMENT OF TRANSPOSON TRANSCRIPTIONAL ACTIVATION IN THIS DISEASE, FOLLOWING THE PILOT STRATEGY PRESENTED HERE, WILL REQUIRE DATABASES GATHERING LARGE ME/CFS EPIGENETIC DATASETS. 2019 10 3798 37 INTERPLAY BETWEEN ACTIVATION OF ENDOGENOUS RETROVIRUSES AND INFLAMMATION AS COMMON PATHOGENIC MECHANISM IN NEUROLOGICAL AND PSYCHIATRIC DISORDERS. HUMAN ENDOGENOUS RETROVIRUSES (ERVS) ARE ANCESTORIAL RETROVIRAL ELEMENTS THAT WERE INTEGRATED INTO OUR GENOME THROUGH GERMLINE INFECTIONS AND INSERTIONS DURING EVOLUTION. THEY HAVE REPEATEDLY BEEN IMPLICATED IN THE AETIOLOGY AND PATHOPHYSIOLOGY OF NUMEROUS HUMAN DISORDERS, PARTICULARLY IN THOSE THAT AFFECT THE CENTRAL NERVOUS SYSTEM. IN ADDITION TO THE KNOWN ASSOCIATION OF ERVS WITH MULTIPLE SCLEROSIS AND AMYOTROPHIC LATERAL SCLEROSIS, A GROWING NUMBER OF STUDIES LINKS THE INDUCTION AND EXPRESSION OF THESE RETROVIRAL ELEMENTS WITH THE ONSET AND SEVERITY OF NEURODEVELOPMENTAL AND PSYCHIATRIC DISORDERS. ALTHOUGH THESE DISORDERS DIFFER IN TERMS OF OVERALL DISEASE PATHOLOGY AND CAUSALITIES, A CERTAIN DEGREE OF (SUBCLINICAL) CHRONIC INFLAMMATION CAN BE IDENTIFIED IN ALL OF THEM. BASED ON THESE COMMONALITIES, WE DISCUSS THE BIDIRECTIONAL RELATIONSHIP BETWEEN ERV EXPRESSION AND INFLAMMATION AND HIGHLIGHT THAT NUMEROUS ENTRY POINTS TO THIS RECIPROCAL SEQUENCE OF EVENTS EXIST, INCLUDING INITIAL INFECTIONS WITH ERV-ACTIVATING PATHOGENS, EXPOSURE TO NON-INFECTIOUS INFLAMMATORY STIMULI, AND CONDITIONS IN WHICH EPIGENETIC SILENCING OF ERV ELEMENTS IS DISRUPTED. 2023 11 3768 28 INTEGRATIVE EPIGENOMICS IN CHRONIC LYMPHOCYTIC LEUKAEMIA: BIOLOGICAL INSIGHTS AND CLINICAL APPLICATIONS. CHRONIC LYMPHOCYTIC LEUKAEMIA (CLL) IS NOT ONLY CHARACTERISED BY DRIVER GENETIC ALTERATIONS BUT BY EXTENSIVE EPIGENETIC CHANGES. OVER THE LAST DECADE, EPIGENOMIC STUDIES HAVE DESCRIBED THE DNA METHYLOME, CHROMATIN ACCESSIBILITY, HISTONE MODIFICATIONS AND THE THREE-DIMENSIONAL (3D) GENOME ARCHITECTURE OF CLL. BEYOND ITS REGULATORY ROLE, THE DNA METHYLOME CONTAINS IMPRINTS OF THE CELLULAR ORIGIN AND PROLIFERATIVE HISTORY OF CLL CELLS. THESE TWO ASPECTS ARE STRONG INDEPENDENT PROGNOSTIC FACTORS. INTEGRATIVE ANALYSES OF CHROMATIN MARKS HAVE UNCOVERED NOVEL REGULATORY ELEMENTS AND ALTERED TRANSCRIPTION FACTOR NETWORKS AS NON-GENETIC MEANS MEDIATING GENE DEREGULATION IN CLL. ADDITIONALLY, CLL CELLS DISPLAY A DISEASE-SPECIFIC PATTERN OF 3D GENOME INTERACTIONS. FROM THE TECHNOLOGICAL PERSPECTIVE, WE ARE CURRENTLY WITNESSING A TRANSITION FROM BULK OMICS TO SINGLE-CELL ANALYSES. THIS REVIEW AIMS AT SUMMARISING THE MAJOR FINDINGS FROM THE EPIGENOMICS FIELD AS WELL AS PROVIDING A PROSPECT OF THE PRESENT AND FUTURE OF SINGLE-CELL ANALYSES IN CLL. 2023 12 6268 31 THE NEUROEPIGENOME: IMPLICATIONS OF CHEMICAL AND PHYSICAL MODIFICATIONS OF GENOMIC DNA IN SCHIZOPHRENIA. SCHIZOPHRENIA IS A CHRONIC MENTAL ILLNESS WITH A SUBSTANTIAL GENETIC COMPONENT. TO UNFOLD THE COMPLEX ETIOLOGY OF SCHIZOPHRENIA, IT IS IMPORTANT TO UNDERSTAND THE INTERPLAY BETWEEN GENETIC AND NONGENETIC FACTORS. GENETIC FACTORS INVOLVE VARIATION IN THE DNA SEQUENCES OF PROTEIN-CODING GENES, WHICH DIRECTLY CONTRIBUTE TO PHENOTYPIC TRAITS, AND VARIATION IN NONCODING SEQUENCES, WHICH COMPRISE 98% OF THE GENOME AND CONTAIN DNA ELEMENTS KNOWN TO PLAY A ROLE IN REGULATING GENE EXPRESSION. THE EPIGENOME REFERS TO THE CHEMICAL MODIFICATIONS ON BOTH DNA AND THE STRUCTURAL PROTEINS THAT PACKAGE DNA INTO THE NUCLEUS, WHICH TOGETHER REGULATE GENE EXPRESSION IN SPECIFIC CELL TYPES, CONDITIONS, AND DEVELOPMENTAL STAGES. THE DYNAMIC NATURE OF THE EPIGENOME MAKES IT AN IDEAL TOOL TO INVESTIGATE THE RELATIONSHIP BETWEEN INHERITED GENETIC MUTATIONS ASSOCIATED WITH SCHIZOPHRENIA AND ALTERED GENE REGULATION THROUGHOUT THE COURSE OF BRAIN DEVELOPMENT. IN THIS REVIEW, WE FOCUS ON THE CURRENT UNDERSTANDING OF THE ROLE OF EPIGENETIC MARKS AND THEIR THREE-DIMENSIONAL NUCLEAR ORGANIZATION IN THE DEVELOPMENTAL TRAJECTORY OF DISTINCT BRAIN CELL TYPES TO DECIPHER THE COMPLEX GENE REGULATORY MECHANISMS THAT ARE DISRUPTED IN SCHIZOPHRENIA. 2022 13 3740 27 INSIGHT INTO GENETIC PREDISPOSITION TO CHRONIC LYMPHOCYTIC LEUKEMIA FROM INTEGRATIVE EPIGENOMICS. GENOME-WIDE ASSOCIATION STUDIES HAVE PROVIDED EVIDENCE FOR INHERITED GENETIC PREDISPOSITION TO CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). TO GAIN INSIGHT INTO THE MECHANISMS UNDERLYING CLL RISK WE ANALYZE CHROMATIN ACCESSIBILITY, ACTIVE REGULATORY ELEMENTS MARKED BY H3K27AC, AND DNA METHYLATION AT 42 RISK LOCI IN UP TO 486 PRIMARY CLLS. WE IDENTIFY THAT RISK LOCI ARE SIGNIFICANTLY ENRICHED FOR ACTIVE CHROMATIN IN CLL WITH EVIDENCE OF BEING CLL-SPECIFIC OR DIFFERENTIALLY REGULATED IN NORMAL B-CELL DEVELOPMENT. WE THEN USE IN SITU PROMOTER CAPTURE HI-C, IN CONJUNCTION WITH GENE EXPRESSION DATA TO REVEAL LIKELY TARGET GENES OF THE RISK LOCI. CANDIDATE TARGET GENES ARE ENRICHED FOR PATHWAYS RELATED TO B-CELL DEVELOPMENT SUCH AS MYC AND BCL2 SIGNALLING. AT 14 LOCI THE ANALYSIS HIGHLIGHTS 63 VARIANTS AS THE PROBABLE FUNCTIONAL BASIS OF CLL RISK. BY INTEGRATING GENETIC AND EPIGENETIC INFORMATION OUR ANALYSIS REVEALS NOVEL INSIGHTS INTO THE RELATIONSHIP BETWEEN INHERITED PREDISPOSITION AND THE REGULATORY CHROMATIN LANDSCAPE OF CLL. 2019 14 3290 35 HIGH CORTISOL IN 5-YEAR-OLD CHILDREN CAUSES LOSS OF DNA METHYLATION IN SINE RETROTRANSPOSONS: A POSSIBLE ROLE FOR ZNF263 IN STRESS-RELATED DISEASES. BACKGROUND: CHILDHOOD STRESS LEADS TO INCREASED RISK OF MANY ADULT DISEASES, SUCH AS MAJOR DEPRESSION AND CARDIOVASCULAR DISEASE. STUDIES SHOW THAT ADULTS WITH EXPERIENCED CHILDHOOD STRESS HAVE SPECIFIC EPIGENETIC CHANGES, BUT TO UNDERSTAND THE PATHWAYS THAT LEAD TO DISEASE, WE ALSO NEED TO STUDY THE EPIGENETIC LINK PROSPECTIVELY IN CHILDREN. RESULTS: HERE, WE STUDIED A HOMOGENOUS GROUP OF 48 5-YEAR-OLD CHILDREN. BY COMBINING HAIR CORTISOL MEASUREMENTS (A WELL-DOCUMENTED BIOMARKER FOR CHRONIC STRESS), WITH WHOLE-GENOME DNA-METHYLATION SEQUENCING, WE SHOW THAT HIGH CORTISOL ASSOCIATES WITH A GENOME-WIDE DECREASE IN DNA METHYLATION AND TARGETS SHORT INTERSPERSED NUCLEAR ELEMENTS (SINES; A TYPE OF RETROTRANSPOSON) AND GENES IMPORTANT FOR CALCIUM TRANSPORT: PHENOMENA COMMONLY AFFECTED IN STRESS-RELATED DISEASES AND IN BIOLOGICAL AGING. MORE IMPORTANTLY, WE IDENTIFY A ZINC-FINGER TRANSCRIPTION FACTOR, ZNF263, WHOSE BINDING SITES WHERE HIGHLY OVERREPRESENTED IN REGIONS EXPERIENCING METHYLATION LOSS. THIS TYPE OF ZINC-FINGER PROTEIN HAS PREVIOUSLY SHOWN TO BE INVOLVED IN THE DEFENSE AGAINST RETROTRANSPOSONS. CONCLUSIONS: OUR RESULTS SHOW THAT STRESS IN PRESCHOOL CHILDREN LEADS TO CHANGES IN DNA METHYLATION SIMILAR TO THOSE SEEN IN BIOLOGICAL AGING. WE SUGGEST THAT THIS MAY AFFECT FUTURE DISEASE SUSCEPTIBILITY BY ALTERATIONS IN THE EPIGENETIC MECHANISMS THAT KEEP RETROTRANSPOSONS DORMANT. FUTURE TREATMENTS FOR STRESS- AND AGE-RELATED DISEASES MAY THEREFORE SEEK TO TARGET ZINC-FINGER PROTEINS THAT EPIGENETICALLY CONTROL RETROTRANSPOSON REACTIVATION, SUCH AS ZNF263. 2015 15 2642 28 EPIGENOMIC AND TRANSCRIPTOMIC ANALYSIS OF CHRONIC INFLAMMATORY DISEASES. CHRONIC INFLAMMATORY DISEASES (CIDS) HAVE COMPLEX PATHOLOGIES THAT RESULT FROM ABERRANT AND PERSISTENT IMMUNE RESPONSES. HOWEVER, THE PRECISE TRIGGERS AND MECHANISMS REMAIN ELUSIVE. AN IMPORTANT ASPECT OF CID RESEARCH FOCUSES ON EPIGENETICS MODIFICATIONS, WHICH REGULATE GENE EXPRESSION AND PROVIDE A DYNAMIC TRANSCRIPTIONAL RESPONSE TO INFLAMMATION. IN RECENT YEARS, MOUNTING EVIDENCE HAS DEMONSTRATED AN ASSOCIATION BETWEEN EPIGENOMIC AND TRANSCRIPTOMIC DYSREGULATION AND THE PHENOTYPES OF CIDS. IN PARTICULAR, EPIGENETIC CHANGES AT CIS-REGULATORY ELEMENTS HAVE PROVIDED NEW INSIGHTS FOR IMMUNE CELL-SPECIFIC ALTERATIONS THAT CONTRIBUTE TO DISEASE ETIOLOGY. FURTHERMORE, THE ADVANCEMENTS IN SINGLE-CELL GENOMICS PROVIDE NOVEL SOLUTIONS TO CELL TYPE HETEROGENEITY, WHICH HAS LONG POSED CHALLENGES FOR CID DIAGNOSIS AND TREATMENT. IN THIS REVIEW, WE DISCUSS THE CURRENT STATE OF EPIGENOMICS RESEARCH OF CID AND THE INSIGHTS DERIVED FROM SINGLE-CELL TRANSCRIPTOMIC AND EPIGENOMIC STUDIES. 2021 16 3918 31 LINKING ABERRANT CHROMATIN FEATURES IN CHRONIC LYMPHOCYTIC LEUKEMIA TO TRANSCRIPTION FACTOR NETWORKS. IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), A DIVERSE SET OF GENETIC MUTATIONS IS EMBEDDED IN A DEREGULATED EPIGENETIC LANDSCAPE THAT DRIVES CANCEROGENESIS. TO ELUCIDATE THE ROLE OF ABERRANT CHROMATIN FEATURES, WE MAPPED DNA METHYLATION, SEVEN HISTONE MODIFICATIONS, NUCLEOSOME POSITIONS, CHROMATIN ACCESSIBILITY, BINDING OF EBF1 AND CTCF, AS WELL AS THE TRANSCRIPTOME OF B CELLS FROM CLL PATIENTS AND HEALTHY DONORS. A GLOBALLY INCREASED HISTONE DEACETYLASE ACTIVITY WAS DETECTED AND HALF OF THE GENOME COMPRISED TRANSCRIPTIONALLY DOWNREGULATED PARTIALLY DNA METHYLATED DOMAINS DEMARCATED BY CTCF CLL SAMPLES DISPLAYED A H3K4ME3 REDISTRIBUTION AND NUCLEOSOME GAIN AT PROMOTERS AS WELL AS CHANGES OF ENHANCER ACTIVITY AND ENHANCER LINKAGE TO TARGET GENES. A DNA BINDING MOTIF ANALYSIS IDENTIFIED TRANSCRIPTION FACTORS THAT GAINED OR LOST BINDING IN CLL AT SITES WITH ABERRANT CHROMATIN FEATURES. THESE FINDINGS WERE INTEGRATED INTO A GENE REGULATORY ENHANCER CONTAINING NETWORK ENRICHED FOR B-CELL RECEPTOR SIGNALING PATHWAY COMPONENTS. OUR STUDY PREDICTS NOVEL MOLECULAR LINKS TO TARGETS OF CLL THERAPIES AND PROVIDES A VALUABLE RESOURCE FOR FURTHER STUDIES ON THE EPIGENETIC CONTRIBUTION TO THE DISEASE. 2019 17 6571 32 TRANSPOSABLE ELEMENTS CROSS KINGDOM BOUNDARIES AND CONTRIBUTE TO INFLAMMATION AND AGEING: SOMATIC ACQUISITION OF FOREIGN TRANSPOSABLE ELEMENTS AS A CATALYST OF GENOME INSTABILITY, EPIGENETIC DYSREGULATION, INFLAMMATION, SENESCENCE, AND AGEING. THE DE-REPRESSION OF TRANSPOSABLE ELEMENTS (TES) IN MAMMALIAN GENOMES IS THOUGHT TO CONTRIBUTE TO GENOME INSTABILITY, INFLAMMATION, AND AGEING, YET IS VIEWED AS A CELL-AUTONOMOUS EVENT. IN CONTRAST TO MAMMALIAN CELLS, PROKARYOTES CONSTANTLY EXCHANGE GENETIC MATERIAL THROUGH TES, CROSSING BOTH CELL AND SPECIES BARRIERS, CONTRIBUTING TO RAPID MICROBIAL EVOLUTION AND DIVERSITY IN COMPLEX COMMUNITIES SUCH AS THE MAMMALIAN GUT. HERE, IT IS PROPOSED THAT TES RELEASED FROM PROKARYOTES IN THE MICROBIOME OR FROM PATHOGENIC INFECTIONS REGULARLY CROSS THE KINGDOM BARRIER TO THE SOMATIC CELLS OF THEIR EUKARYOTIC HOSTS. IT IS PROPOSED THIS HORIZONTAL TRANSFER OF TES FROM MICROBE TO HOST IS A STOCHASTIC, ONGOING CATALYST OF GENOME DESTABILIZATION, RESULTING IN STRUCTURAL AND EPIGENETIC VARIATIONS, AND ACTIVATION OF WELL-EVOLVED HOST DEFENSE MECHANISMS CONTRIBUTING TO INFLAMMATION, SENESCENCE, AND BIOLOGICAL AGEING. IT IS PROPOSED THAT INNATE IMMUNITY PATHWAYS DEFEND AGAINST THE HORIZONTAL ACQUISITION OF MICROBIAL TES, AND THAT ACTIVATION OF THIS PATHWAY DURING HORIZONTAL TRANSPOSON TRANSFER PROMOTES CHRONIC INFLAMMATION DURING AGEING. FINALLY, IT IS SUGGESTED THAT HORIZONTAL ACQUISITION OF PROKARYOTIC TES INTO MAMMALIAN GENOMES HAS BEEN MASKED AND SUBSEQUENTLY UNDER-REPORTED DUE TO FLAWS IN CURRENT SEQUENCING PIPELINES, AND NEW STRATEGIES TO UNCOVER THESE EVENTS ARE PROPOSED. 2020 18 6800 38 [EPIGENETIC DISTURBANCES IN SYSTEMIC LUPUS ERYTHEMATOSUS]. SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) IS A CHRONIC INFLAMMATORY AUTOIMMUNE DISEASE THAT RESULTS IN UNCONTROLLED IMMUNE SYSTEM ACTIVATION AND OVERPRODUCTION OF AUTOANTIBODIES. THE PATHOGENESIS OF THE DISEASE IS COMPLEX AND NOT FULLY UNDERSTOOD, NEVERTHELESS, GENETIC AND ENVIRONMENTAL FACTORS PLAY AN IMPORTANT ROLE. SO FAR, ABOUT 30 GENES HAVE BEEN IDENTIFIED TO BE INVOLVED IN THE SLE PATHOMECHANISM. HOWEVER, NOT ALL GENETICALLY PREDISPOSED INDIVIDUALS DEVELOP THE DISEASE. THIS PHENOMENON CAN BE ASSOCIATED WITH EPIGENETIC CHANGES THAT OCCUR UNDER THE INFLUENCE OF ENVIRONMENTAL FACTORS. THEY CAN AFFECT GENE EXPRESSION AND ARE POTENTIALLY HEREDITARY, BUT DO NOT LEAD TO CHANGES IN THE NUCLEOTIDE SEQUENCE. EPIGENETIC DYSFUNCTIONS, IDENTIFIED IN THE COURSE OF THE DISEASE, LEAD TO CHANGES IN THE EXPRESSION OF GENES THAT PLAY A KEY ROLE IN MAINTAINING THE BODY'S IMMUNE TOLERANCE. MAJOR MECHANISMS OF EPIGENETIC VARIABILITY ARE: DNA METHYLATION, HISTONE PROTEIN MODIFICATION, NON-CODING RNA EXPRESSION, AS WELL AS GENE IMPRINTING. THE MAJOR EPIGENETIC DYSFUNCTIONS AFFECTING THE PATHOGENESIS OF THE DISEASE ARE GLOBAL HYPOMETHYLATION ON CD4+ T CELLS RESULTING FROM ERK SIGNALING PATHWAY REGULATION, HISTONE HYPOACETYLATION, HISTONE H3 LYSINE METHYLATION, AND REACTIVATION OF INACTIVE CHROMOSOME X. IN LUPUS PATIENTS, VARIOUS EPIGENETIC MECHANISMS INTERACT WITH EACH OTHER, ENHANCING THE EXPRESSION OR SILENCING OF GENES RESPONSIBLE FOR THE PRODUCTION OF PRO-INFLAMMATORY AND ANTI-INFLAMMATORY CYTOKINES AND ACTIVATION OF AUTOREACTIVE B-LYMPHOCYTES. 2018 19 3949 29 LNCRNAS IN T LYMPHOCYTES: RNA REGULATION AT THE HEART OF THE IMMUNE RESPONSE. GENOME-WIDE ANALYSES IN THE LAST DECADE HAVE UNCOVERED THE PRESENCE OF A LARGE NUMBER OF LONG NON-PROTEIN-CODING TRANSCRIPTS THAT SHOW HIGHLY TISSUE- AND STATE-SPECIFIC EXPRESSION PATTERNS. HIGH-THROUGHPUT SEQUENCING ANALYSES IN DIVERSE SUBSETS OF IMMUNE CELLS HAVE REVEALED A COMPLEX AND DYNAMIC EXPRESSION PATTERN FOR THESE LONG NONCODING RNAS (LNCRNAS) THAT CORRELATE WITH THE FUNCTIONAL STATES OF IMMUNE CELLS. ALTHOUGH THE VAST MAJORITY OF LNCRNAS EXPRESSED IN IMMUNE CELLS REMAIN UNSTUDIED, FUNCTIONAL STUDIES PERFORMED ON A SMALL SUBSET HAVE INDICATED THAT THEIR STATE-SPECIFIC EXPRESSIONS PATTERN FREQUENTLY HAS A REGULATORY IMPACT ON THE FUNCTION OF IMMUNE CELLS. IN VIVO AND IN VITRO STUDIES HAVE POINTED TO THE INVOLVEMENT OF LNCRNAS IN A WIDE VARIETY OF CELLULAR PROCESSES, INCLUDING BOTH THE INNATE AND ADAPTIVE IMMUNE RESPONSE THROUGH MECHANISMS RANGING FROM EPIGENETIC AND TRANSCRIPTIONAL REGULATION TO SEQUESTRATION OF FUNCTIONAL MOLECULES IN SUBCELLULAR COMPARTMENTS. THIS REVIEW WILL FOCUS MAINLY ON THE ROLE OF LNCRNAS IN CD4(+) AND CD8(+) T CELLS, WHICH PLAY PIVOTAL ROLES IN ADAPTIVE IMMUNITY. RECENT STUDIES HAVE POINTED TO KEY PHYSIOLOGICAL FUNCTIONS FOR LNCRNAS DURING SEVERAL DEVELOPMENTAL AND FUNCTIONAL STAGES OF THE LIFE CYCLE OF LYMPHOCYTES. ALTHOUGH LNCRNAS PLAY IMPORTANT PHYSIOLOGICAL ROLES IN LYMPHOCYTIC RESPONSE TO ANTIGENIC STIMULATION, DIFFERENTIATION INTO EFFECTOR CELLS, AND SECRETION OF CYTOKINES, THEIR DYSREGULATED EXPRESSION CAN PROMOTE OR SUSTAIN PATHOLOGICAL STATES SUCH AS AUTOIMMUNITY, CHRONIC INFLAMMATION, CANCER, AND VIREMIA. THIS, TOGETHER WITH THEIR HIGHLY CELL TYPE-SPECIFIC EXPRESSION PATTERNS, MAKES LNCRNAS IDEAL THERAPEUTIC TARGETS AND UNDERSCORES THE NEED FOR ADDITIONAL STUDIES INTO THE ROLE OF THESE UNDERSTUDIED TRANSCRIPTS IN ADAPTIVE IMMUNE RESPONSE. 2021 20 5157 26 PRE-NEOPLASTIC EPIGENETIC DISRUPTION OF TRANSCRIPTIONAL ENHANCERS IN CHRONIC INFLAMMATION. CHRONIC PERIODONTITIS (CP) IS A CHRONIC INFLAMMATORY DISEASE INDEPENDENTLY ASSOCIATED WITH HIGHER INCIDENCE OF ORAL CAVITY SQUAMOUS CELL CARCINOMA (OSCC). HOWEVER, THE MOLECULAR MECHANISM RESPONSIBLE FOR THIS INCREASED INCIDENCE IS UNKNOWN. HERE WE PROFILED THE DNA METHYLOME OF CP PATIENTS AND HEALTHY CONTROLS AND COMPARED TO A LARGE SET OF OSCC SAMPLES FROM TCGA. WE OBSERVED A SIGNIFICANT OVERLAP BETWEEN THE ALTERED DNA METHYLATION PATTERNS IN CP AND IN OSCC, SUGGESTING AN EMERGENCE OF A PRE-NEOPLASTIC EPIGENOME IN CP. REMARKABLY, THE HYPERMETHYLATED CPGS IN CP WERE SIGNIFICANTLY ENRICHED FOR ENHANCER ELEMENTS. THIS ABERRANT ENHANCER METHYLATION IS FUNCTIONAL AND ABLE TO DISRUPT ENHANCER ACTIVITY BY PREVENTING THE BINDING OF CHROMATIN LOOPING FACTORS. THIS STUDY PROVIDES NEW INSIGHTS ON THE MOLECULAR MECHANISMS LINKING CHRONIC INFLAMMATION AND TUMOR PREDISPOSITION, HIGHLIGHTING THE ROLE OF EPIGENETIC DISRUPTION OF TRANSCRIPTIONAL ENHANCERS. 2016