1 129 167 A UNIQUE VIRULENCE GENE OCCUPIES A PRINCIPAL POSITION IN IMMUNE EVASION BY THE MALARIA PARASITE PLASMODIUM FALCIPARUM. MUTUALLY EXCLUSIVE GENE EXPRESSION, WHEREBY ONLY ONE MEMBER OF A MULTI-GENE FAMILY IS SELECTED FOR ACTIVATION, IS USED BY THE MALARIA PARASITE PLASMODIUM FALCIPARUM TO ESCAPE THE HUMAN IMMUNE SYSTEM AND PERPETUATE LONG-TERM, CHRONIC INFECTIONS. A FAMILY OF GENES CALLED VAR ENCODES THE CHIEF ANTIGENIC AND VIRULENCE DETERMINANT OF P. FALCIPARUM MALARIA. VAR GENES ARE TRANSCRIBED IN A MUTUALLY EXCLUSIVE MANNER, WITH SWITCHING BETWEEN ACTIVE GENES RESULTING IN ANTIGENIC VARIATION. WHILE RECENT WORK HAS SHED CONSIDERABLE LIGHT ON THE EPIGENETIC BASIS FOR VAR GENE ACTIVATION AND SILENCING, HOW SWITCHING IS CONTROLLED REMAINS A MYSTERY. IN PARTICULAR, SWITCHING SEEMS NOT TO BE RANDOM, BUT INSTEAD APPEARS TO BE COORDINATED TO RESULT IN TIMELY ACTIVATION OF INDIVIDUAL GENES LEADING TO SEQUENTIAL WAVES OF ANTIGENICALLY DISTINCT PARASITE POPULATIONS. THE MOLECULAR BASIS FOR THIS APPARENT COORDINATION IS UNKNOWN. HERE WE SHOW THAT VAR2CSA, AN UNUSUAL AND HIGHLY CONSERVED VAR GENE, OCCUPIES A UNIQUE POSITION WITHIN THE VAR GENE SWITCHING HIERARCHY. INDUCTION OF SWITCHING THROUGH THE DESTABILIZATION OF VAR SPECIFIC CHROMATIN USING BOTH GENETIC AND CHEMICAL METHODS REPEATEDLY LED TO THE RAPID AND EXCLUSIVE ACTIVATION OF VAR2CSA. ADDITIONAL EXPERIMENTS DEMONSTRATED THAT THESE REPRESENT "TRUE" SWITCHING EVENTS AND NOT SIMPLY DE-SILENCING OF THE VAR2CSA PROMOTER, AND THAT ACTIVATION IS LIMITED TO THE UNIQUE LOCUS ON CHROMOSOME 12. COMBINED WITH TRANSLATIONAL REPRESSION OF VAR2CSA TRANSCRIPTS, FREQUENT "DEFAULT" SWITCHING TO THIS LOCUS AND DETECTION OF VAR2CSA UNTRANSLATED TRANSCRIPTS IN NON-PREGNANT INDIVIDUALS, THESE DATA SUGGEST THAT VAR2CSA COULD PLAY A CENTRAL ROLE IN COORDINATING SWITCHING, FULFILLING A PREDICTION MADE BY MATHEMATICAL MODELS DERIVED FROM POPULATION SWITCHING PATTERNS. THESE STUDIES PROVIDE THE FIRST INSIGHTS INTO THE MECHANISMS BY WHICH VAR GENE SWITCHING IS COORDINATED AS WELL AS AN EXAMPLE OF HOW A PHARMACOLOGICAL AGENT CAN DISRUPT ANTIGENIC VARIATION IN PLASMODIUM FALCIPARUM. 2015 2 6179 50 THE HUMAN MALARIA PARASITE PLASMODIUM FALCIPARUM CAN SENSE ENVIRONMENTAL CHANGES AND RESPOND BY ANTIGENIC SWITCHING. THE PRIMARY ANTIGENIC AND VIRULENCE DETERMINANT OF THE HUMAN MALARIA PARASITE PLASMODIUM FALCIPARUM IS A VARIANT SURFACE PROTEIN CALLED PFEMP1. DIFFERENT FORMS OF PFEMP1 ARE ENCODED BY A MULTICOPY GENE FAMILY CALLED VAR, AND SWITCHING BETWEEN ACTIVE GENES ENABLES THE PARASITES TO EVADE THE ANTIBODY RESPONSE OF THEIR HUMAN HOSTS. VAR GENE SWITCHING IS KEY FOR THE MAINTENANCE OF CHRONIC INFECTIONS; HOWEVER, WHAT CONTROLS SWITCHING IS UNKNOWN, ALTHOUGH IT HAS BEEN SUGGESTED TO OCCUR AT A CONSTANT FREQUENCY WITH LITTLE OR NO ENVIRONMENTAL INFLUENCE. VAR GENE TRANSCRIPTION IS CONTROLLED EPIGENETICALLY THROUGH THE ACTIVITY OF HISTONE METHYLTRANSFERASES (HMTS). STUDIES IN MODEL SYSTEMS HAVE SHOWN THAT METABOLISM AND EPIGENETIC CONTROL OF GENE EXPRESSION ARE LINKED THROUGH THE AVAILABILITY OF INTRACELLULAR S-ADENOSYLMETHIONINE (SAM), THE PRINCIPAL METHYL DONOR IN BIOLOGICAL METHYLATION MODIFICATIONS, WHICH CAN FLUCTUATE BASED ON NUTRIENT AVAILABILITY. TO DETERMINE WHETHER ENVIRONMENTAL CONDITIONS AND CHANGES IN METABOLISM CAN INFLUENCE VAR GENE EXPRESSION, P. FALCIPARUM WAS CULTURED IN MEDIA WITH ALTERED CONCENTRATIONS OF NUTRIENTS INVOLVED IN SAM METABOLISM. WE FOUND THAT CONDITIONS THAT INFLUENCE LIPID METABOLISM INDUCE VAR GENE SWITCHING, INDICATING THAT PARASITES CAN RESPOND TO CHANGES IN THEIR ENVIRONMENT BY ALTERING VAR GENE EXPRESSION PATTERNS. GENETIC MODIFICATIONS THAT DIRECTLY MODIFIED EXPRESSION OF THE ENZYMES THAT CONTROL SAM LEVELS SIMILARLY LED TO PROFOUND CHANGES IN VAR GENE EXPRESSION, CONFIRMING THAT CHANGES IN SAM AVAILABILITY MODULATE VAR GENE SWITCHING. THESE OBSERVATIONS DIRECTLY CHALLENGE THE PARADIGM THAT ANTIGENIC VARIATION IN P. FALCIPARUM FOLLOWS AN INTRINSIC, PROGRAMED SWITCHING RATE, WHICH OPERATES INDEPENDENTLY OF ANY EXTERNAL STIMULI. 2023 3 2091 47 EPIGENETIC DYSREGULATION OF VIRULENCE GENE EXPRESSION IN SEVERE PLASMODIUM FALCIPARUM MALARIA. CHRONIC INFECTIONS WITH THE HUMAN MALARIA PARASITE PLASMODIUM FALCIPARUM DEPEND ON ANTIGENIC VARIATION. P. FALCIPARUM ERYTHROCYTE MEMBRANE PROTEIN 1 (PFEMP1), THE MAJOR ERYTHROCYTE SURFACE ANTIGEN MEDIATING PARASITE SEQUESTRATION IN THE MICROVASCULATURE, IS ENCODED IN PARASITES BY A HIGHLY DIVERSE FAMILY OF VAR GENES. ANTIGENIC SWITCHING IS MEDIATED BY CLONAL VARIATION IN VAR EXPRESSION, AND RECENT IN VITRO STUDIES HAVE DEMONSTRATED A ROLE FOR EPIGENETIC PROCESSES IN VAR REGULATION. EXPRESSION OF PARTICULAR PFEMP1 VARIANTS MAY RESULT IN PARASITE ENRICHMENT IN DIFFERENT TISSUES, A FACTOR IN THE DEVELOPMENT OF SEVERE DISEASE. HERE, WE STUDY IN VIVO HUMAN INFECTIONS AND PROVIDE EVIDENCE THAT INFECTION-INDUCED STRESS RESPONSES IN THE HOST CAN MODIFY PFEMP1 EXPRESSION VIA THE PERTURBATION OF EPIGENETIC MECHANISMS. OUR WORK SUGGESTS THAT SEVERE DISEASE MAY NOT BE THE DIRECT RESULT OF AN ADAPTIVE VIRULENCE STRATEGY TO MAXIMIZE PARASITE SURVIVAL BUT THAT IT MAY INDICATE A LOSS OF CONTROL OF THE CAREFULLY REGULATED PROCESS OF ANTIGENIC SWITCHING THAT MAINTAINS CHRONIC INFECTIONS. 2012 4 1219 66 CRISPR/CAS9 GENOME EDITING REVEALS THAT THE INTRON IS NOT ESSENTIAL FOR VAR2CSA GENE ACTIVATION OR SILENCING IN PLASMODIUM FALCIPARUM. PLASMODIUM FALCIPARUM RELIES ON MONOALLELIC EXPRESSION OF 1 OF 60 VAR VIRULENCE GENES FOR ANTIGENIC VARIATION AND HOST IMMUNE EVASION. EACH VAR GENE CONTAINS A CONSERVED INTRON WHICH HAS BEEN IMPLICATED IN PREVIOUS STUDIES IN BOTH ACTIVATION AND REPRESSION OF TRANSCRIPTION VIA SEVERAL EPIGENETIC MECHANISMS, INCLUDING INTERACTION WITH THE VAR PROMOTER, PRODUCTION OF LONG NONCODING RNAS (LNCRNAS), AND LOCALIZATION TO REPRESSIVE PERINUCLEAR SITES. HOWEVER, FUNCTIONAL STUDIES HAVE RELIED PRIMARILY ON ARTIFICIAL EXPRESSION CONSTRUCTS. USING THE RECENTLY DEVELOPED P. FALCIPARUM CLUSTERED REGULARLY INTERSPACED SHORT PALINDROMIC REPEATS (CRISPR)/CAS9 SYSTEM, WE DIRECTLY DELETED THE VAR2CSA P. FALCIPARUM 3D7_1200600 (PF3D7_1200600) ENDOGENOUS INTRON, RESULTING IN AN INTRONLESS VAR GENE IN A NATURAL, MARKER-FREE CHROMOSOMAL CONTEXT. DELETION OF THE VAR2CSA INTRON RESULTED IN AN UPREGULATION OF TRANSCRIPTION OF THE VAR2CSA GENE IN RING-STAGE PARASITES AND SUBSEQUENT EXPRESSION OF THE PFEMP1 PROTEIN IN LATE-STAGE PARASITES. INTRON DELETION DID NOT AFFECT THE NORMAL TEMPORAL REGULATION AND SUBSEQUENT TRANSCRIPTIONAL SILENCING OF THE VAR GENE IN TROPHOZOITES BUT DID RESULT IN INCREASED RATES OF VAR GENE SWITCHING IN SOME MUTANT CLONES. TRANSCRIPTIONAL REPRESSION OF THE INTRONLESS VAR2CSA GENE COULD BE ACHIEVED VIA LONG-TERM CULTURE OR PANNING WITH THE CD36 RECEPTOR, AFTER WHICH REACTIVATION WAS POSSIBLE WITH CHONDROITIN SULFATE A (CSA) PANNING. THESE DATA SUGGEST THAT THE VAR2CSA INTRON IS NOT REQUIRED FOR SILENCING OR ACTIVATION IN RING-STAGE PARASITES BUT POINT TO A SUBTLE ROLE IN REGULATION OF SWITCHING WITHIN THE VAR GENE FAMILY.IMPORTANCEPLASMODIUM FALCIPARUM IS THE MOST VIRULENT SPECIES OF MALARIA PARASITE, CAUSING HIGH RATES OF MORBIDITY AND MORTALITY IN THOSE INFECTED. CHRONIC INFECTION DEPENDS ON AN IMMUNE EVASION MECHANISM TERMED ANTIGENIC VARIATION, WHICH IN TURN RELIES ON MONOALLELIC EXPRESSION OF 1 OF ~60 VAR GENES. UNDERSTANDING ANTIGENIC VARIATION AND THE TRANSCRIPTIONAL REGULATION OF MONOALLELIC EXPRESSION IS IMPORTANT FOR DEVELOPING DRUGS AND/OR VACCINES. THE VAR GENE FAMILY ENCODES THE ANTIGENIC SURFACE PROTEINS THAT DECORATE INFECTED ERYTHROCYTES. UNTIL RECENTLY, STUDYING THE UNDERLYING GENETIC ELEMENTS THAT REGULATE MONOALLELIC EXPRESSION IN P. FALCIPARUM WAS DIFFICULT, AND MOST STUDIES RELIED ON ARTIFICIAL SYSTEMS SUCH AS EPISOMAL REPORTER GENES. OUR STUDY WAS THE FIRST TO USE CRISPR/CAS9 GENOME EDITING FOR THE FUNCTIONAL STUDY OF AN IMPORTANT, CONSERVED GENETIC ELEMENT OF VAR GENES-THE INTRON-IN AN ENDOGENOUS, EPISOME-FREE MANNER. OUR FINDINGS SHED LIGHT ON THE ROLE OF THE VAR GENE INTRON IN TRANSCRIPTIONAL REGULATION OF MONOALLELIC EXPRESSION. 2017 5 4395 27 MODM DNA METHYLTRANSFERASE METHYLOME ANALYSIS REVEALS A POTENTIAL ROLE FOR MORAXELLA CATARRHALIS PHASEVARIONS IN OTITIS MEDIA. MORAXELLA CATARRHALIS IS A SIGNIFICANT CAUSE OF OTITIS MEDIA AND EXACERBATIONS OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE. HERE, WE CHARACTERIZE A PHASE-VARIABLE DNA METHYLTRANSFERASE (MODM), WHICH CONTAINS 5'-CAAC-3' REPEATS IN ITS OPEN READING FRAME THAT MEDIATE HIGH-FREQUENCY MUTATION RESULTING IN REVERSIBLE ON/OFF SWITCHING OF MODM EXPRESSION. THREE MODM ALLELES HAVE BEEN IDENTIFIED (MODM1-3), WITH MODM2 BEING THE MOST COMMONLY FOUND ALLELE. USING SINGLE-MOLECULE, REAL-TIME (SMRT) GENOME SEQUENCING AND METHYLOME ANALYSIS, WE HAVE DETERMINED THAT THE MODM2 METHYLATION TARGET IS 5'-GAR(M6)AC-3', AND 100% OF THESE SITES ARE METHYLATED IN THE GENOME OF THE M. CATARRHALIS 25239 MODM2 ON STRAIN. PROTEOMIC ANALYSIS OF MODM2 ON AND OFF VARIANTS REVEALED THAT MODM2 REGULATES EXPRESSION OF MULTIPLE GENES THAT HAVE POTENTIAL ROLES IN COLONIZATION, INFECTION, AND PROTECTION AGAINST HOST DEFENSES. INVESTIGATION OF THE DISTRIBUTION OF MODM ALLELES IN A PANEL OF M. CATARRHALIS STRAINS, ISOLATED FROM THE NASOPHARYNX OF HEALTHY CHILDREN OR MIDDLE EAR EFFUSIONS FROM PATIENTS WITH OTITIS MEDIA, REVEALED A STATISTICALLY SIGNIFICANT ASSOCIATION OF MODM3 WITH OTITIS MEDIA ISOLATES. THE MODULATION OF GENE EXPRESSION VIA THE MODM PHASE-VARIABLE REGULON (PHASEVARION), AND THE SIGNIFICANT ASSOCIATION OF THE MODM3 ALLELE WITH OTITIS MEDIA, SUGGESTS A KEY ROLE FOR MODM PHASEVARIONS IN THE PATHOGENESIS OF THIS ORGANISM. 2014 6 17 44 5' FLANKING REGION OF VAR GENES NUCLEATE HISTONE MODIFICATION PATTERNS LINKED TO PHENOTYPIC INHERITANCE OF VIRULENCE TRAITS IN MALARIA PARASITES. IN THE HUMAN MALARIA PARASITE PLASMODIUM FALCIPARUM ANTIGENIC VARIATION FACILITATES LONG-TERM CHRONIC INFECTION OF THE HOST. THIS IS ACHIEVED BY SEQUENTIAL EXPRESSION OF A SINGLE MEMBER OF THE 60-MEMBER VAR FAMILY. HERE WE SHOW THAT THE 5' FLANKING REGION NUCLEATES EPIGENETIC EVENTS STRONGLY LINKED TO THE MAINTENANCE OF MONO-ALLELIC VAR GENE EXPRESSION PATTERN DURING PARASITE PROLIFERATION. TRI- AND DIMETHYLATION OF HISTONE H3 LYSINE 4 PEAK IN THE 5' UPSTREAM REGION OF TRANSCRIBED VAR AND DURING THE POISED STATE (NON-TRANSCRIBED PHASE OF VAR GENES DURING THE 48 H ASEXUAL LIFE CYCLE), 'BOOKMARKING' THIS MEMBER FOR RE-ACTIVATION AT THE ONSET OF THE NEXT CYCLE. HISTONE H3 LYSINE 9 TRIMETHYLATION ACTS AS AN ANTAGONIST TO LYSINE 4 METHYLATION TO ESTABLISH STABLY SILENT VAR GENE STATES ALONG THE 5' FLANKING AND CODING REGION. FURTHERMORE, WE SHOW THAT COMPETITION EXISTS BETWEEN H3K9 METHYLATION AND H3K9 ACETYLATION IN THE 5' FLANKING REGION AND THAT THESE MARKS CONTRIBUTE EPIGENETICALLY TO REPRESSING OR ACTIVATING VAR GENE EXPRESSION. OUR WORK POINTS TO A PIVOTAL ROLE OF THE HISTONE METHYL MARK WRITING AND READING MACHINERY IN THE PHENOTYPIC INHERITANCE OF VIRULENCE TRAITS IN THE MALARIA PARASITE. 2007 7 1218 59 CRISPR INTERFERENCE OF A CLONALLY VARIANT GC-RICH NONCODING RNA FAMILY LEADS TO GENERAL REPRESSION OF VAR GENES IN PLASMODIUM FALCIPARUM. THE HUMAN MALARIA PARASITE PLASMODIUM FALCIPARUM USES MUTUALLY EXCLUSIVE EXPRESSION OF THE PFEMP1-ENCODING VAR GENE FAMILY TO EVADE THE HOST IMMUNE SYSTEM. DESPITE PROGRESS IN THE MOLECULAR UNDERSTANDING OF THE DEFAULT SILENCING MECHANISM, THE ACTIVATION MECHANISM OF THE UNIQUELY EXPRESSED VAR MEMBER REMAINS ELUSIVE. A GC-RICH NONCODING RNA (NCRNA) GENE FAMILY HAS COEVOLVED WITH PLASMODIUM SPECIES THAT EXPRESS VAR GENES. HERE, WE SHOW THAT THIS NCRNA FAMILY IS TRANSCRIBED IN A CLONALLY VARIANT MANNER, WITH PREDOMINANT TRANSCRIPTION OF A SINGLE MEMBER OCCURRING WHEN THE NCRNA IS LOCATED ADJACENT TO AND UPSTREAM OF AN ACTIVE VAR GENE. WE DEVELOPED A SPECIFIC CRISPR INTERFERENCE (CRISPRI) STRATEGY THAT ALLOWED FOR THE TRANSCRIPTIONAL REPRESSION OF ALL GC-RICH MEMBERS. A LACK OF GC-RICH NCRNA TRANSCRIPTION LED TO THE DOWNREGULATION OF THE ENTIRE VAR GENE FAMILY IN RING-STAGE PARASITES. STRIKINGLY, IN MATURE BLOOD-STAGE PARASITES, THE GC-RICH NCRNA CRISPRI AFFECTED THE TRANSCRIPTION PATTERNS OF OTHER CLONALLY VARIANT GENE FAMILIES, INCLUDING THE DOWNREGULATION OF ALL PFMC-2TM MEMBERS. WE PROVIDE EVIDENCE FOR THE KEY ROLE OF GC-RICH NCRNA TRANSCRIPTION IN VAR GENE ACTIVATION AND DISCOVERED A MOLECULAR LINK BETWEEN THE TRANSCRIPTIONAL CONTROL OF VARIOUS CLONALLY VARIANT MULTIGENE FAMILIES INVOLVED IN PARASITE VIRULENCE. THIS WORK OPENS NEW AVENUES FOR ELUCIDATING THE MOLECULAR PROCESSES THAT CONTROL IMMUNE EVASION AND PATHOGENESIS IN P. FALCIPARUMIMPORTANCEPLASMODIUM FALCIPARUM IS THE DEADLIEST MALARIA PARASITE SPECIES, ACCOUNTING FOR THE VAST MAJORITY OF DISEASE CASES AND DEATHS. THE VIRULENCE OF THIS PARASITE IS RELIANT UPON THE MUTUALLY EXCLUSIVE EXPRESSION OF CYTOADHERENCE PROTEINS ENCODED BY THE 60-MEMBER VAR GENE FAMILY. ANTIGENIC VARIATION OF THIS MULTIGENE FAMILY SERVES AS AN IMMUNE EVASION MECHANISM, ULTIMATELY LEADING TO CHRONIC INFECTION AND PATHOGENESIS. UNDERSTANDING THE REGULATION MECHANISM OF ANTIGENIC VARIATION IS KEY TO DEVELOPING NEW THERAPEUTIC AND CONTROL STRATEGIES. OUR STUDY UNCOVERS A NOVEL LAYER IN THE EPIGENETIC REGULATION OF TRANSCRIPTION OF THIS FAMILY OF VIRULENCE GENES BY MEANS OF A MULTIGENE-TARGETING CRISPR INTERFERENCE APPROACH. 2020 8 340 46 ALTERATIONS IN LOCAL CHROMATIN ENVIRONMENT ARE INVOLVED IN SILENCING AND ACTIVATION OF SUBTELOMERIC VAR GENES IN PLASMODIUM FALCIPARUM. PLASMODIUM FALCIPARUM ERYTHROCYTE MEMBRANE PROTEIN 1 (PFEMP1), ENCODED BY THE VAR GENE FAMILY, UNDERGOES ANTIGENIC VARIATION AND PLAYS AN IMPORTANT ROLE IN CHRONIC INFECTION AND SEVERE MALARIA. ONLY A SINGLE VAR GENE IS TRANSCRIBED PER PARASITE, AND EPIGENETIC CONTROL MECHANISMS ARE FUNDAMENTAL IN THIS STRATEGY OF MUTUALLY EXCLUSIVE TRANSCRIPTION. WE SHOW THAT SUBTELOMERIC UPSB VAR GENE PROMOTERS CARRIED ON EPISOMES ARE SILENCED BY DEFAULT, AND THAT PROMOTER ACTIVATION IS SUFFICIENT TO SILENCE ALL OTHER FAMILY MEMBERS. HOWEVER, THEY ARE ACTIVE BY DEFAULT WHEN PLACED DOWNSTREAM OF A SECOND ACTIVE VAR PROMOTER, UNDERSCORING THE SIGNIFICANCE OF LOCAL CHROMATIN ENVIRONMENT AND NUCLEAR COMPARTMENTALIZATION IN VAR PROMOTER REGULATION. NATIVE CHROMATIN COVERING THE SPE2-REPEAT ARRAY IN UPSB PROMOTERS IS RESISTANT TO NUCLEASE DIGESTION, AND INSERTION OF THESE REGULATORY ELEMENTS INTO A HETEROLOGOUS PROMOTER CAUSES LOCAL ALTERATIONS IN NUCLEOSOMAL ORGANIZATION AND PROMOTER REPRESSION. OUR FINDINGS SUGGEST A COMMON LOGIC UNDERLYING THE TRANSCRIPTIONAL CONTROL OF ALL VAR GENES, AND HAVE IMPORTANT IMPLICATIONS FOR OUR UNDERSTANDING OF THE EPIGENETIC PROCESSES INVOLVED IN THE REGULATION OF THIS MAJOR VIRULENCE GENE FAMILY. 2007 9 2378 26 EPIGENETIC REGULATION OF VASCULAR SMOOTH MUSCLE CELL PHENOTYPE SWITCHING IN ATHEROSCLEROTIC ARTERY REMODELING: A MINI-REVIEW. ATHEROSCLEROSIS IS A CHRONIC INFLAMMATORY DISEASE CHARACTERIZED BY EXTENSIVE REMODELING OF MEDIUM AND LARGE-SIZED ARTERIES. INWARD REMODELING (=LUMEN SHRINKAGE) OF THE VASCULAR WALLS IS THE UNDERLYING CAUSE FOR ISCHEMIA IN TARGET ORGANS. THEREFORE, INWARD REMODELING CAN BE CONSIDERED THE PREDOMINANT FEATURE OF ATHEROSCLEROTIC PATHOLOGY. OUTWARD REMODELING (=LUMEN ENLARGEMENT) IS A PHYSIOLOGICAL RESPONSE COMPENSATING FOR LUMEN SHRINKAGE CAUSED BY NEOINTIMAL HYPERPLASIA, BUT AS A PATHOLOGICAL RESPONSE TO CHANGES IN BLOOD FLOW, OUTWARD REMODELING LEADS TO SUBSTANTIAL ARTERIAL WALL THINNING. THINNED VASCULAR WALLS ARE PRONE TO RUPTURE, AND SUBSEQUENT THROMBUS FORMATION ACCOUNTS FOR THE MAJORITY OF ACUTE CARDIOVASCULAR EVENTS. PATHOLOGICAL REMODELING IS DRIVEN BY INFLAMMATORY CELLS WHICH INDUCE VASCULAR SMOOTH MUSCLE CELLS TO SWITCH FROM QUIESCENT TO A PROLIFERATIVE AND MIGRATORY PHENOTYPE. AFTER DECADES OF INTENSIVE RESEARCH, THE MOLECULAR MECHANISMS OF ARTERIAL REMODELING ARE STARTING TO UNFOLD. IN THIS MINI-REVIEW, WE SUMMARIZE THE CURRENT KNOWLEDGE OF THE EPIGENETIC AND TRANSCRIPTIONAL REGULATION OF VASCULAR SMOOTH MUSCLE CELL PHENOTYPE SWITCHING FROM THE CONTRACTILE TO THE SYNTHETIC PHENOTYPE INVOLVED IN ARTERIAL REMODELING AND DISCUSS POTENTIAL THERAPEUTIC OPTIONS. 2021 10 6261 34 THE MORAXELLA CATARRHALIS PHASE-VARIABLE DNA METHYLTRANSFERASE MODM3 IS AN EPIGENETIC REGULATOR THAT AFFECTS BACTERIAL SURVIVAL IN AN IN VIVO MODEL OF OTITIS MEDIA. BACKGROUND: MORAXELLA CATARRHALIS IS A LEADING CAUSE OF OTITIS MEDIA (OM) AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD). M. CATARRHALIS CONTAINS A TYPE III DNA ADENINE METHYLTRANSFERASE (MODM) THAT IS PHASE-VARIABLY EXPRESSED (I.E., ITS EXPRESSION IS SUBJECT TO RANDOM, REVERSIBLE ON/OFF SWITCHING). MODM HAS SIX TARGET RECOGNITION DOMAIN ALLELES (MODM1-6), AND WE HAVE PREVIOUSLY SHOWN THAT MODM2 IS THE PREDOMINANT ALLELE, WHILE MODM3 IS ASSOCIATED WITH OM. PHASE-VARIABLE DNA METHYLTRANSFERASES MEDIATE EPIGENETIC REGULATION AND MODULATE PATHOGENESIS IN SEVERAL BACTERIA. MODM2 OF M. CATARRHALIS REGULATES THE EXPRESSION OF A PHASEVARION CONTAINING GENES IMPORTANT FOR COLONIZATION AND INFECTION. HERE WE DESCRIBE THE PHASE-VARIABLE EXPRESSION OF MODM3, THE MODM3 METHYLATION SITE AND THE SUITE OF GENES REGULATED WITHIN THE MODM3 PHASEVARION. RESULTS: PHASE-VARIABLE EXPRESSION OF MODM3, MEDIATED BY VARIATION IN LENGTH OF A 5'-(CAAC)(N)-3' TETRANUCLEOTIDE REPEAT TRACT IN THE OPEN READING FRAME WAS DEMONSTRATED IN M. CATARRHALIS STRAIN CCRI-195ME WITH GENESCAN FRAGMENT LENGTH ANALYSIS AND WESTERN IMMUNOBLOT. WE DETERMINED THAT MODM3 IS AN ACTIVE N6-ADENINE METHYLTRANSFERASE THAT METHYLATES THE SEQUENCE 5'-AC(M6)ATC-3'. METHYLATION WAS DETECTED AT ALL 4446 5'-ACATC-3' SITES IN THE GENOME WHEN MODM3 IS EXPRESSED. RNASEQ ANALYSIS IDENTIFIED 31 GENES THAT ARE DIFFERENTIALLY EXPRESSED BETWEEN MODM3 ON AND OFF VARIANTS, INCLUDING FIVE GENES THAT ARE INVOLVED IN THE RESPONSE TO OXIDATIVE AND NITROSATIVE STRESS, WITH POTENTIAL ROLES IN BIOFILM FORMATION AND SURVIVAL IN ANAEROBIC ENVIRONMENTS. AN IN VIVO CHINCHILLA (CHINCHILLA LANIGERA) MODEL OF OTITIS MEDIA DEMONSTRATED THAT TRANSBULLAR CHALLENGE WITH THE MODM3 OFF VARIANT RESULTED IN AN INCREASED MIDDLE EAR BACTERIAL LOAD COMPARED TO A MODM3 ON VARIANT. IN ADDITION, CO-INFECTION EXPERIMENTS WITH NTHI AND M. CATARRHALIS MODM3 ON OR MODM3 OFF VARIANTS REVEALED THAT PHASE VARIATION OF MODM3 ALTERED SURVIVAL OF NTHI IN THE MIDDLE EAR DURING EARLY AND LATE STAGE INFECTION. CONCLUSIONS: PHASE VARIATION OF MODM3 EPIGENETICALLY REGULATES THE EXPRESSION OF A PHASEVARION CONTAINING MULTIPLE GENES THAT ARE POTENTIALLY IMPORTANT IN THE PROGRESSION OF OTITIS MEDIA. 2019 11 2273 39 EPIGENETIC REGULATION ALTERS BIOFILM ARCHITECTURE AND COMPOSITION IN MULTIPLE CLINICAL ISOLATES OF NONTYPEABLE HAEMOPHILUS INFLUENZAE. BIOFILMS PLAY A CRITICAL ROLE IN THE COLONIZATION, PERSISTENCE, AND PATHOGENESIS OF MANY HUMAN PATHOGENS. MULTIPLE MUCOSA-ASSOCIATED PATHOGENS HAVE EVOLVED A MECHANISM OF RAPID ADAPTATION, TERMED THE PHASEVARION, WHICH FACILITATES A COORDINATED REGULATION OF NUMEROUS GENES THROUGHOUT THE BACTERIAL GENOME. THIS EPIGENETIC REGULATION OCCURS VIA PHASE VARIATION OF A DNA METHYLTRANSFERASE, MOD. THE PHASEVARION OF NONTYPEABLE HAEMOPHILUS INFLUENZAE (NTHI) SIGNIFICANTLY AFFECTS THE SEVERITY OF EXPERIMENTAL OTITIS MEDIA AND REGULATES SEVERAL DISEASE-RELATED PROCESSES. HOWEVER, THE ROLE OF THE NTHI PHASEVARION IN BIOFILM FORMATION IS UNCLEAR. THE PRESENT STUDY SHOWS THAT THE PHASEVARIONS OF MULTIPLE NTHI CLINICAL ISOLATES REGULATE IN VITRO BIOFILM FORMATION UNDER DISEASE-SPECIFIC MICROENVIRONMENTAL CONDITIONS. THE IMPACT OF PHASEVARION REGULATION WAS GREATEST UNDER ALKALINE CONDITIONS THAT MIMIC THOSE KNOWN TO OCCUR IN THE MIDDLE EAR DURING DISEASE. UNDER ALKALINE CONDITIONS, NTHI STRAINS THAT EXPRESS THE MODA2 METHYLTRANSFERASE FORMED BIOFILMS WITH SIGNIFICANTLY GREATER BIOMASS AND LESS DISTINCT ARCHITECTURE THAN THOSE FORMED BY A MODA2-DEFICIENT POPULATION. THE BIOFILMS FORMED BY NTHI STRAINS THAT EXPRESS MODA2 ALSO CONTAINED LESS EXTRACELLULAR DNA (EDNA) AND SIGNIFICANTLY LESS EXTRACELLULAR HU, A DNABII DNA-BINDING PROTEIN CRITICAL FOR BIOFILM STRUCTURAL STABILITY. STABLE BIOFILM STRUCTURE IS CRITICAL FOR BACTERIAL PATHOGENESIS AND PERSISTENCE IN MULTIPLE EXPERIMENTAL MODELS OF DISEASE. THESE RESULTS IDENTIFY A ROLE FOR THE PHASEVARION IN REGULATION OF BIOFILM FORMATION, A PROCESS INTEGRAL TO THE CHRONIC NATURE OF MANY INFECTIONS. UNDERSTANDING THE ROLE OF THE PHASEVARION IN BIOFILM FORMATION IS CRITICAL TO THE DEVELOPMENT OF PREVENTION AND TREATMENT STRATEGIES FOR THESE CHRONIC DISEASES.IMPORTANCE UPPER RESPIRATORY TRACT INFECTIONS ARE THE NUMBER ONE REASON FOR A CHILD TO VISIT THE EMERGENCY DEPARTMENT, AND OTITIS MEDIA (MIDDLE EAR INFECTION) RANKS THIRD OVERALL. BIOFILMS CONTRIBUTE SIGNIFICANTLY TO THE CHRONIC NATURE OF BACTERIAL RESPIRATORY TRACT INFECTIONS, INCLUDING OTITIS MEDIA, AND MAKE THESE DISEASES PARTICULARLY DIFFICULT TO TREAT. SEVERAL MUCOSA-ASSOCIATED HUMAN PATHOGENS UTILIZE A MECHANISM OF RAPID ADAPTATION TERMED THE PHASEVARION, OR PHASEVARIABLE REGULON, TO RESIST ENVIRONMENTAL AND HOST IMMUNE PRESSURES. IN THIS STUDY, WE ASSESSED THE ROLE OF THE PHASEVARION IN REGULATION OF BIOFILM FORMATION BY NONTYPEABLE HAEMOPHILUS INFLUENZAE (NTHI), WHICH CAUSES NUMEROUS RESPIRATORY TRACT DISEASES. WE FOUND THAT THE NTHI PHASEVARION REGULATES BIOFILM STRUCTURE AND CRITICAL BIOFILM MATRIX COMPONENTS UNDER DISEASE-SPECIFIC CONDITIONS. THE FINDINGS OF THIS WORK COULD BE SIGNIFICANT IN THE DESIGN OF IMPROVED STRATEGIES AGAINST NTHI INFECTIONS, AS WELL AS DISEASES DUE TO OTHER PATHOGENS THAT UTILIZE A PHASEVARION. 2018 12 6695 34 VARIANT GENE EXPRESSION AND ANTIGENIC VARIATION BY MALARIA PARASITES. MALARIA IS A SIGNIFICANT THREAT THROUGHOUT THE DEVELOPING WORLD. AMONG THE MOST FASCINATING ASPECTS OF THE PROTOZOAN PARASITES RESPONSIBLE FOR THIS DISEASE ARE THE METHODS THEY EMPLOY TO AVOID THE IMMUNE SYSTEM AND PERPETUATE CHRONIC INFECTIONS. KEY AMONG THESE IS ANTIGENIC VARIATION: BY SYSTEMATICALLY ALTERING ANTIGENS THAT ARE DISPLAYED TO THE HOST'S IMMUNE SYSTEM, THE PARASITE RENDERS THE ADAPTIVE IMMUNE RESPONSE INEFFECTIVE. FOR PLASMODIUM FALCIPARUM, THE SPECIES RESPONSIBLE FOR THE MOST SEVERE FORM OF HUMAN MALARIA, THIS PROCESS INVOLVES A COMPLICATED MOLECULAR MECHANISM THAT RESULTS IN CONTINUOUSLY CHANGING PATTERNS OF VARIANT-ANTIGEN-ENCODING GENE EXPRESSION. ALTHOUGH MANY FEATURES OF THIS PROCESS REMAIN OBSCURE, SIGNIFICANT PROGRESS HAS BEEN MADE IN RECENT YEARS TO DECIPHER VARIOUS MOLECULAR ASPECTS OF THE REGULATORY CASCADE THAT CAUSES CHRONIC INFECTION. 2017 13 4493 30 MORAXELLA CATARRHALIS INDUCES INFLAMMATORY RESPONSE OF BRONCHIAL EPITHELIAL CELLS VIA MAPK AND NF-KAPPAB ACTIVATION AND HISTONE DEACETYLASE ACTIVITY REDUCTION. MORAXELLA CATARRHALIS IS A MAJOR CAUSE OF INFECTIOUS EXACERBATIONS OF CHRONIC OBSTRUCTIVE LUNG DISEASE (COPD) AND MAY ALSO CONTRIBUTE TO THE PATHOGENESIS OF COPD. LITTLE IS KNOWN ABOUT M. CATARRHALIS-BRONCHIAL EPITHELIUM INTERACTION. WE INVESTIGATED ACTIVATION OF M. CATARRHALIS INFECTED BRONCHIAL EPITHELIAL CELLS AND CHARACTERIZED THE SIGNAL TRANSDUCTION PATHWAYS. MOREOVER, WE TESTED THE HYPOTHESIS THAT THE M. CATARRHALIS-INDUCED CYTOKINE EXPRESSION IS REGULATED BY ACETYLATION OF HISTONE RESIDUES AND CONTROLLED BY HISTONE DEACETYLASE ACTIVITY (HDAC). WE DEMONSTRATED THAT M. CATARRHALIS INDUCED A STRONG TIME- AND DOSE-DEPENDENT INFLAMMATORY RESPONSE IN THE BRONCHIAL EPITHELIAL CELL LINE (BEAS-2B), CHARACTERIZED BY THE RELEASE OF IL-8 AND GM-CSF. FOR THIS CYTOKINE LIBERATION ACTIVATION OF THE ERK AND P38 MITOGEN-ACTIVATED PROTEIN (MAP) KINASES AND TRANSCRIPTION FACTOR NF-KAPPAB WAS REQUIRED. FURTHERMORE, M. CATARRHALIS-INFECTED BRONCHIAL EPITHELIAL CELLS SHOWED AN ENHANCED ACETYLATION OF HISTONE H3 AND H4 GLOBALLY AND AT THE PROMOTER OF THE IL8 GENE. PREVENTING HISTONE DEACETYLATION BY THE HISTONE DEACETYLASE INHIBITOR TRICHOSTATIN A AUGMENTED THE M. CATARRHALIS-INDUCED IL-8 RESPONSE. AFTER EXPOSURE TO M. CATARRHALIS, WE FOUND A DECREASE IN GLOBAL HISTONE DEACETYLASE EXPRESSION AND ACTIVITY. OUR FINDINGS SUGGEST THAT M. CATARRHALIS-INDUCED ACTIVATION OF IL8 GENE TRANSCRIPTION WAS CAUSED BY INTERFERENCE WITH EPIGENETIC MECHANISMS REGULATING IL8 GENE ACCESSIBILITY. OUR FINDINGS PROVIDE INSIGHT INTO IMPORTANT MOLECULAR AND CELLULAR MECHANISMS OF M. CATARRHALIS-INDUCED ACTIVATION OF HUMAN BRONCHIAL EPITHELIUM. 2006 14 4490 28 MONOCYTE EPIGENETICS AND INNATE IMMUNITY TO MALARIA: YET ANOTHER LEVEL OF COMPLEXITY? CHILDREN UNDER THE AGE OF 5 YEARS LIVING IN AREAS OF MODERATE TO HIGH MALARIA TRANSMISSION ARE HIGHLY SUSCEPTIBLE TO CLINICAL MALARIA WITH FEVER THAT PROMPTS TREATMENT OF BLOOD STAGE INFECTION WITH ANTI-MALARIAL DRUGS. IN CONTRAST, OLDER SCHOOL AGE CHILDREN FREQUENTLY EXPERIENCE SUBCLINICAL MALARIA, I.E. CHRONIC PLASMODIUM FALCIPARUM PARASITEMIA WITHOUT FEVER OR OTHER CLINICAL SYMPTOMS. THE ROLE OF INNATE IMMUNE CELLS IN REGULATING INFLAMMATION AT A LEVEL THAT IS SUFFICIENT TO CONTROL THE PARASITE BIOMASS, WHILE AT THE SAME TIME MAINTAINING A DISEASE-TOLERANT CLINICAL PHENOTYPE, I.E., SUBCLINICAL MALARIA, IS NOT WELL UNDERSTOOD. RECENT STUDIES SUGGEST THAT HOST EPIGENETIC MECHANISMS UNDERLIE THE INNATE IMMUNE HOMEOSTASIS ASSOCIATED WITH SUBCLINICAL MALARIA. THIS CURRENT OPINION ARTICLE PRESENTS EVIDENCE SUPPORTING THE NOTION THAT MODIFICATIONS OF THE HOST MONOCYTE/MACROPHAGE EPIGENOME REGULATE INNATE IMMUNE FUNCTIONS PERTINENT TO SUBCLINICAL MALARIA. 2022 15 3625 53 IN VIVO GENOME AND METHYLOME ADAPTATION OF CAG-NEGATIVE HELICOBACTER PYLORI DURING EXPERIMENTAL HUMAN INFECTION. MULTIPLE STUDIES HAVE DEMONSTRATED RAPID BACTERIAL GENOME EVOLUTION DURING CHRONIC INFECTION WITH HELICOBACTER PYLORI IN CONTRAST, LITTLE WAS KNOWN ABOUT GENETIC CHANGES DURING THE FIRST STAGES OF INFECTION, WHEN SELECTIVE PRESSURE IS LIKELY TO BE HIGHEST. USING SINGLE-MOLECULE, REAL-TIME (SMRT) AND ILLUMINA SEQUENCING TECHNOLOGIES, WE ANALYZED GENOME AND METHYLOME EVOLUTION DURING THE FIRST 10 WEEKS OF INFECTION BY COMPARING THE CAG PATHOGENICITY ISLAND (CAGPAI)-NEGATIVE H. PYLORI CHALLENGE STRAIN BCS 100 WITH PAIRS OF H. PYLORI REISOLATES FROM GASTRIC ANTRUM AND CORPUS BIOPSY SPECIMENS OF 10 HUMAN VOLUNTEERS WHO HAD BEEN INFECTED WITH THIS STRAIN AS PART OF A VACCINE TRIAL. MOST GENETIC CHANGES DETECTED IN THE REISOLATES AFFECTED GENES WITH A SURFACE-RELATED ROLE OR A PREDICTED FUNCTION IN PEPTIDE UPTAKE. APART FROM PHENOTYPIC CHANGES OF THE BACTERIAL ENVELOPE, A DUPLICATION OF THE CATALASE GENE WAS OBSERVED IN ONE REISOLATE, WHICH RESULTED IN HIGHER CATALASE ACTIVITY AND IMPROVED SURVIVAL UNDER OXIDATIVE STRESS CONDITIONS. THE METHYLOMES ALSO VARIED IN SOME OF THE REISOLATES, MOSTLY BY ACTIVITY SWITCHING OF PHASE-VARIABLE METHYLTRANSFERASE (MTASE) GENES. THE OBSERVED IN VIVO MUTATION SPECTRUM WAS REMARKABLE FOR A VERY HIGH PROPORTION OF NONSYNONYMOUS MUTATIONS. ALTHOUGH THE DATA SHOWED SUBSTANTIAL WITHIN-STRAIN GENOME DIVERSITY IN THE CHALLENGE STRAIN, MOST ANTRUM AND CORPUS REISOLATES FROM THE SAME VOLUNTEERS WERE HIGHLY SIMILAR TO EACH OTHER, INDICATING THAT THE CHALLENGE INFECTION REPRESENTS A MAJOR SELECTIVE BOTTLENECK SHAPING THE TRANSMITTED POPULATION. OUR FINDINGS SUGGEST RAPID IN VIVO SELECTION OF H. PYLORI DURING EARLY-PHASE INFECTION PROVIDING ADAPTATION TO DIFFERENT INDIVIDUALS BY COMMON MECHANISMS OF GENETIC AND EPIGENETIC ALTERATIONS.IMPORTANCE EXCEPTIONAL GENETIC DIVERSITY AND VARIABILITY ARE HALLMARKS OF HELICOBACTER PYLORI, BUT THE BIOLOGICAL ROLE OF THIS PLASTICITY REMAINS INCOMPLETELY UNDERSTOOD. HERE, WE HAD THE RARE OPPORTUNITY TO INVESTIGATE THE MOLECULAR EVOLUTION DURING THE FIRST WEEKS OF H. PYLORI INFECTION BY COMPARING THE GENOMES AND EPIGENOMES OF H. PYLORI STRAIN BCS 100 USED TO CHALLENGE HUMAN VOLUNTEERS IN A VACCINE TRIAL WITH THOSE OF BACTERIA REISOLATED FROM THE VOLUNTEERS 10 WEEKS AFTER THE CHALLENGE. THE DATA PROVIDE MOLECULAR INSIGHTS INTO THE PROCESS OF ESTABLISHMENT OF THIS HIGHLY VERSATILE PATHOGEN IN 10 DIFFERENT HUMAN INDIVIDUAL HOSTS, SHOWING, FOR EXAMPLE, SELECTION FOR CHANGES IN HOST-INTERACTION MOLECULES AS WELL AS CHANGES IN EPIGENETIC METHYLATION PATTERNS. THE DATA PROVIDE IMPORTANT CLUES TO THE EARLY ADAPTATION OF H. PYLORI TO NEW HOST NICHES AFTER TRANSMISSION, WHICH WE BELIEVE IS VITAL TO UNDERSTAND ITS SUCCESS AS A CHRONIC PATHOGEN AND DEVELOP MORE EFFICIENT TREATMENTS AND VACCINES. 2020 16 4415 28 MOLECULAR AND CELLULAR MECHANISMS THAT INDUCE ARTERIAL CALCIFICATION BY INDOXYL SULFATE AND P-CRESYL SULFATE. THE PROTEIN-BOUND UREMIC TOXINS, INDOXYL SULFATE (IS) AND P-CRESYL SULFATE (PCS), ARE CONSIDERED TO BE HARMFUL VASCULAR TOXINS. ARTERIAL MEDIA CALCIFICATION, OR THE DEPOSITION OF CALCIUM PHOSPHATE CRYSTALS IN THE ARTERIES, CONTRIBUTES SIGNIFICANTLY TO CARDIOVASCULAR COMPLICATIONS, INCLUDING LEFT VENTRICULAR HYPERTROPHY, HYPERTENSION, AND IMPAIRED CORONARY PERFUSION IN THE ELDERLY AND PATIENTS WITH CHRONIC KIDNEY DISEASE (CKD) AND DIABETES. RECENTLY, WE REPORTED THAT BOTH IS AND PCS TRIGGER MODERATE TO SEVERE CALCIFICATION IN THE AORTA AND PERIPHERAL VESSELS OF CKD RATS. THIS REVIEW DESCRIBES THE MOLECULAR AND CELLULAR MECHANISMS BY WHICH THESE UREMIC TOXINS INDUCE ARTERIAL MEDIA CALCIFICATION. A COMPLEX INTERPLAY BETWEEN INFLAMMATION, COAGULATION, AND LIPID METABOLISM PATHWAYS, INFLUENCED BY EPIGENETIC FACTORS, IS CRUCIAL IN IS/PCS-INDUCED ARTERIAL MEDIA CALCIFICATION. HIGH LEVELS OF GLUCOSE ARE LINKED TO THESE EVENTS, SUGGESTING THAT A GOOD BALANCE BETWEEN GLUCOSE AND LIPID LEVELS MIGHT BE IMPORTANT. ON THE CELLULAR LEVEL, EFFECTS ON ENDOTHELIAL CELLS, WHICH ACT AS THE PRIMARY SENSORS OF CIRCULATING PATHOLOGICAL TRIGGERS, MIGHT BE AS IMPORTANT AS THOSE ON VASCULAR SMOOTH MUSCLE CELLS. ENDOTHELIAL DYSFUNCTION, PROVOKED BY IS AND PCS TRIGGERED OXIDATIVE STRESS, MAY BE CONSIDERED A KEY EVENT IN THE ONSET AND DEVELOPMENT OF ARTERIAL MEDIA CALCIFICATION. IN THIS REVIEW A NUMBER OF IMPORTANT OUTSTANDING QUESTIONS SUCH AS THE ROLE OF MIRNA'S, PHENOTYPIC SWITCHING OF BOTH ENDOTHELIAL AND VASCULAR SMOOTH MUSCLE CELLS AND NEW TYPES OF PROGRAMMED CELL DEATH IN ARTERIAL MEDIA CALCIFICATION RELATED TO PROTEIN-BOUND UREMIC TOXINS ARE PUT FORWARD AND DISCUSSED. 2020 17 5096 43 PLASMODIUM FALCIPARUM SET2 DOMAIN IS ALLOSTERICALLY REGULATED BY ITS PHD-LIKE DOMAIN TO METHYLATE AT H3K36. THE ANTIGENIC VARIATION IS AN ESSENTIAL MECHANISM EMPLOYED BY THE MALARIA PARASITE TO ESTABLISH A CHRONIC INFECTION IN HUMANS. THREE MAJOR VIRULENT PROTEINS EMP1, RIFINS, AND STEVOR HAVE BEEN IMPLICATED IN CONTRIBUTING TO THE ANTIGENIC VARIATION PROCESS AND ARE ENCODED BY MULTIGENE FAMILIES IN PLASMODIUM SPP. THE KEY VIRULENCE FACTOR PFEMP1 IS ENCODED BY VAR GENES, AND IT EXHIBITS A MUTUALLY EXCLUSIVE TRANSCRIPTIONAL SWITCHING BETWEEN VAR GENES, ENSURING AN INDIVIDUAL PARASITE ONLY TRANSCRIBES A SINGLE VAR GENE AT A TIME. EXPRESSION OF VAR GENES IS TIGHTLY REGULATED BY TWO HISTONE EPIGENETIC METHYLATION MARKS H3K36ME3 AND H3K9ME3, OF WHICH THE H3K36ME3 MARK IS HIGHLY ENRICHED ON TRANSCRIPTION START SITES (TSSS) OF SUPPRESSED VAR GENES IN P. FALCIPARUM. HOWEVER, THE MECHANISMS OF H3K36ME3 MARK PROPAGATION ON ALL THE 59 VAR GENES OF P. FALCIPARUM ARE NOT KNOWN. HERE, WE HAVE IDENTIFIED A PHD (PLANT HOMEODOMAIN-LIKE DOMAIN) LIKE DOMAIN PRESENT WITHIN THE PFSET2 PROTEIN THAT SPECIFICALLY BINDS TO THE H3K36ME2 MARK, AN INTERMEDIATE PRODUCT OF THE H3K36ME3 MARK FORMATION ON THE NUCLEOSOME. SURPRISINGLY, WE HAVE FOUND THAT PHD - H3K36ME2 INTERACTION LEADS TO STIMULATION OF SET2 DOMAIN ACTIVITY ON THE NUCLEOSOME SUBSTRATES. THE ALLOSTERIC STIMULATION OF THE PFSET2 DOMAIN BY PHD-LIKE DOMAIN PRESENT WITHIN THE SAME PROTEIN SUGGESTS A NOVEL MECHANISM OF H3K36ME3 MARK PROPAGATION ON VAR GENES OF P. FALCIPARUM. THIS STUDY PROPOSES ALLOSTERIC REGULATION OF PFSET2 PROTEIN BY H3K36ME2 MARK AS AN ESSENTIAL MECHANISM OF VAR GENES SUPPRESSION TO ENSURE SUCCESSFUL ANTIGENIC VARIATION BY THE MALARIA PARASITE. 2021 18 1124 12 COMPLETE GENOME SEQUENCE OF MORAXELLA CATARRHALIS STRAIN CCRI-195ME, ISOLATED FROM THE MIDDLE EAR. MORAXELLA CATARRHALIS IS AN IMPORTANT BACTERIAL PATHOGEN THAT CAUSES OTITIS MEDIA AND EXACERBATIONS OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE. HERE, WE REPORT THE COMPLETE GENOME SEQUENCE OF M. CATARRHALIS STRAIN CCRI-195ME, WHICH CONTAINS THE PHASE-VARIABLE EPIGENETIC REGULATOR MODM3. 2017 19 5596 26 ROLES OF HISTONE ACETYLATION MODIFIERS AND OTHER EPIGENETIC REGULATORS IN VASCULAR CALCIFICATION. VASCULAR CALCIFICATION (VC) IS CHARACTERIZED BY CALCIUM DEPOSITION INSIDE ARTERIES AND IS CLOSELY ASSOCIATED WITH THE MORBIDITY AND MORTALITY OF ATHEROSCLEROSIS, CHRONIC KIDNEY DISEASE, DIABETES, AND OTHER CARDIOVASCULAR DISEASES (CVDS). VC IS NOW WIDELY KNOWN TO BE AN ACTIVE PROCESS OCCURRING IN VASCULAR SMOOTH MUSCLE CELLS (VSMCS) INVOLVING MULTIPLE MECHANISMS AND FACTORS. THESE MECHANISMS SHARE FEATURES WITH THE PROCESS OF BONE FORMATION, SINCE THE PHENOTYPE SWITCHING FROM THE CONTRACTILE TO THE OSTEOCHONDROGENIC PHENOTYPE ALSO OCCURS IN VSMCS DURING VC. IN ADDITION, VC CAN BE REGULATED BY EPIGENETIC FACTORS, INCLUDING DNA METHYLATION, HISTONE MODIFICATION, AND NONCODING RNAS. ALTHOUGH VC IS COMMONLY OBSERVED IN PATIENTS WITH CHRONIC KIDNEY DISEASE AND CVD, SPECIFIC DRUGS FOR VC HAVE NOT BEEN DEVELOPED. THUS, DISCOVERING NOVEL THERAPEUTIC TARGETS MAY BE NECESSARY. IN THIS REVIEW, WE SUMMARIZE THE CURRENT EXPERIMENTAL EVIDENCE REGARDING THE ROLE OF EPIGENETIC REGULATORS INCLUDING HISTONE DEACETYLASES AND PROPOSE THE THERAPEUTIC IMPLICATION OF THESE REGULATORS IN THE TREATMENT OF VC. 2020 20 3656 35 INDUCIBLE PRMT1 ABLATION IN ADULT VASCULAR SMOOTH MUSCLE LEADS TO CONTRACTILE DYSFUNCTION AND AORTIC DISSECTION. VASCULAR SMOOTH MUSCLE CELLS (VSMCS) HAVE REMARKABLE PLASTICITY IN RESPONSE TO DIVERSE ENVIRONMENTAL CUES. ALTHOUGH THESE CELLS ARE VERSATILE, CHRONIC STRESS CAN TRIGGER VSMC DYSFUNCTION, WHICH ULTIMATELY LEADS TO VASCULAR DISEASES SUCH AS AORTIC ANEURYSM AND ATHEROSCLEROSIS. PROTEIN ARGININE METHYLTRANSFERASE 1 (PRMT1) IS A MAJOR ENZYME CATALYZING ASYMMETRIC ARGININE DIMETHYLATION OF PROTEINS THAT ARE SOURCES OF ASYMMETRIC DIMETHYLARGININE (ADMA), AN ENDOGENOUS INHIBITOR OF NITRIC OXIDE SYNTHASE. ALTHOUGH A POTENTIAL ROLE OF PRMT1 IN VASCULAR PATHOGENESIS HAS BEEN PROPOSED, ITS ROLE IN VASCULAR FUNCTION HAS YET TO BE CLARIFIED. HERE, WE INVESTIGATED THE ROLE AND UNDERLYING MECHANISM OF PRMT1 IN VASCULAR SMOOTH MUSCLE CONTRACTILITY AND FUNCTION. THE EXPRESSION OF PRMT1 AND CONTRACTILE-RELATED GENES WAS SIGNIFICANTLY DECREASED IN THE AORTAS OF ELDERLY HUMANS AND PATIENTS WITH AORTIC ANEURYSMS. MICE WITH VSMC-SPECIFIC PRMT1 ABLATION (SMKO) EXHIBITED PARTIAL LETHALITY, LOW BLOOD PRESSURE AND AORTIC DILATION. THE PRMT1-ABLATED AORTAS SHOWED AORTIC DISSECTION WITH ELASTIC FIBER DEGENERATION AND CELL DEATH. EX VIVO AND IN VITRO ANALYSES INDICATED THAT PRMT1 ABLATION SIGNIFICANTLY DECREASED THE CONTRACTILITY OF THE AORTA AND TRACTION FORCES OF VSMCS. PRMT1 ABLATION DOWNREGULATED THE EXPRESSION OF CONTRACTILE GENES SUCH AS MYOCARDIN WHILE UPREGULATING THE EXPRESSION OF SYNTHETIC GENES, THUS CAUSING THE CONTRACTILE TO SYNTHETIC PHENOTYPIC SWITCH OF VSMCS. IN ADDITION, MECHANISTIC STUDIES DEMONSTRATED THAT PRMT1 DIRECTLY REGULATES MYOCARDIN GENE ACTIVATION BY MODULATING EPIGENETIC HISTONE MODIFICATIONS IN THE MYOCARDIN PROMOTER REGION. THUS, OUR STUDY DEMONSTRATES THAT VSMC PRMT1 IS ESSENTIAL FOR VASCULAR HOMEOSTASIS AND THAT ITS ABLATION CAUSES AORTIC DILATION/DISSECTION THROUGH IMPAIRED MYOCARDIN EXPRESSION. 2021