1 6658 138 UPREGULATED LNCRNA H19 SPONGES MIR-106A-5P AND CONTRIBUTES TO ALDOSTERONE-INDUCED VASCULAR CALCIFICATION VIA ACTIVATING THE RUNX2-DEPENDENT PATHWAY. BACKGROUND: EXCESS ALDOSTERONE IS IMPLICATED IN VASCULAR CALCIFICATION (VC), BUT THE MECHANISM BY WHICH ALDOSTERONE-MR (MINERALOCORTICOID RECEPTOR) COMPLEX PROMOTES VC IS UNCLEAR. EMERGING EVIDENCE INDICATES THAT LONG-NONCODING RNA H19 (H19) PLAYS A CRITICAL ROLE IN VC. WE EXAMINED WHETHER ALDOSTERONE-INDUCED OSTEOGENIC DIFFERENTIATION OF VASCULAR SMOOTH MUSCLE CELLS (VSMCS) THROUGH H19 EPIGENETIC MODIFICATION OF RUNX2 (RUNT-RELATED TRANSCRIPTION FACTOR-2) IN A MR-DEPENDENT MANNER. METHODS: WE INDUCED IN VIVO RAT MODEL OF CHRONIC KIDNEY DISEASE USING A HIGH ADENINE AND PHOSPHATE DIET TO EXPLORE THE RELATIONSHIP AMONG ALDOSTERONE, MR, H19, AND VC. WE ALSO CULTURED HUMAN AORTIC VSMCS TO EXPLORE THE ROLES OF H19 IN ALDOSTERONE-MR COMPLEX-INDUCED OSTEOGENIC DIFFERENTIATION AND CALCIFICATION OF VSMCS. RESULTS: H19 AND RUNX2 WERE SIGNIFICANTLY INCREASED IN ALDOSTERONE-INDUCED VSMC OSTEOGENIC DIFFERENTIATION AND VC, BOTH IN VITRO AND IN VIVO, WHICH WERE SIGNIFICANTLY BLOCKED BY THE MR ANTAGONIST SPIRONOLACTONE. MECHANISTICALLY, OUR FINDINGS REVEAL THAT THE ALDOSTERONE-ACTIVATED MR BOUND TO H19 PROMOTER AND INCREASED ITS TRANSCRIPTIONAL ACTIVITY, AS DETERMINED BY CHROMATIN IMMUNOPRECIPITATION, ELECTROPHORETIC MOBILITY SHIFT ASSAY, AND LUCIFERASE REPORTER ASSAY. SILENCING H19 INCREASED MICRORNA-106A-5P (MIR-106A-5P) EXPRESSION, WHICH SUBSEQUENTLY INHIBITED ALDOSTERONE-INDUCED RUNX2 EXPRESSION AT THE POSTTRANSCRIPTIONAL LEVEL. IMPORTANTLY, WE OBSERVED A DIRECT INTERACTION BETWEEN H19 AND MIR-106A-5P, AND DOWNREGULATION OF MIR-106A-5P EFFICIENTLY REVERSED THE SUPPRESSION OF RUNX2 INDUCED BY H19 SILENCING. CONCLUSIONS: OUR STUDY CLARIFIES A NOVEL MECHANISM BY WHICH UPREGULATION OF H19 CONTRIBUTES TO ALDOSTERONE-MR COMPLEX-PROMOTED RUNX2-DEPENDENT VSMC OSTEOGENIC DIFFERENTIATION AND VC THROUGH SPONGING MIR-106A-5P. THESE FINDINGS HIGHLIGHT A POTENTIAL THERAPEUTIC TARGET FOR ALDOSTERONE-INDUCED VC. 2023 2 5495 29 REVIEW ON CIRCULAR RNAS AND NEW INSIGHTS INTO THEIR ROLES IN CANCER. CIRCULAR RNAS (CIRCRNAS) ARE A VERY INTERESTING CLASS OF CONSERVED SINGLE-STRANDED RNA MOLECULES DERIVED FROM EXONIC OR INTRONIC SEQUENCES BY PRECURSOR MRNA BACK-SPLICING. UNLIKE CANONICAL LINEAR RNAS, CIRCRNAS FORM COVALENTLY CLOSED, CONTINUOUS STABLE LOOPS WITHOUT A 5'END CAP AND 3'END POLY(A) TAIL, AND THEREFORE ARE RESISTANT TO EXONUCLEASE DIGESTION. THE MAJORITY OF CIRCRNAS ARE HIGHLY ABUNDANT, AND CONSERVED ACROSS DIFFERENT SPECIES WITH A TISSUE OR DEVELOPMENTAL-STAGE-SPECIFIC EXPRESSION. CIRCRNAS HAVE BEEN SHOWN TO PLAY IMPORTANT ROLES AS MICRORNA SPONGES, REGULATORS OF GENE SPLICING AND TRANSCRIPTION, RNA-BINDING PROTEIN SPONGES AND PROTEIN/PEPTIDE TRANSLATORS. EMERGING EVIDENCE REVEALS THAT CIRCRNAS FUNCTION IN VARIOUS HUMAN DISEASES, PARTICULARLY CANCERS, AND MAY FUNCTION AS BETTER PREDICTIVE BIOMARKERS AND THERAPEUTIC TARGETS FOR CANCER TREATMENT. IN CONSIDERATION OF THEIR POTENTIAL CLINICAL RELEVANCE, CIRCRNAS HAVE BECOME A NEW RESEARCH HOTSPOT IN THE FIELD OF TUMOR PATHOLOGY. IN THE PRESENT STUDY, THE CURRENT UNDERSTANDING OF THE BIOGENESIS, CHARACTERISTICS, DATABASES, RESEARCH METHODS, BIOLOGICAL FUNCTIONS SUBCELLULAR DISTRIBUTION, EPIGENETIC REGULATION, EXTRACELLULAR TRANSPORT AND DEGRADATION OF CIRCRNAS WAS DISCUSSED. IN PARTICULAR, THE MULTIPLE DATABASES AND METHODS INVOLVED IN CIRCRNA RESEARCH WERE FIRST SUMMARIZED, AND THE RECENT ADVANCES IN DETERMINING THE POTENTIAL ROLES OF CIRCRNAS IN TUMOR GROWTH, MIGRATION AND INVASION, WHICH RENDER CIRCRNAS BETTER PREDICTIVE BIOMARKERS, WERE DESCRIBED. FURTHERMORE, FUTURE PERSPECTIVES FOR THE CLINICAL APPLICATION OF CIRCRNAS IN THE MANAGEMENT OF PATIENTS WITH CANCER WERE PROPOSED, WHICH COULD PROVIDE NEW INSIGHTS INTO CIRCRNAS IN THE FUTURE. 2021 3 6907 23 [THE ROLE OF THE CIRCULAR RNAS IN MULTIPLE SCLEROSIS AND OTHER NEUROIMMUNE DISORDERS]. IN RECENT YEARS NON-CODING RNAS HAVE RECEIVED INCREASING ATTENTION AS AN IMPORTANT EPIGENETIC MECHANISM, WITH PARTICULAR ROLE OF MICRO RNAS. AS THE REGULATION OF MIRNA EXPRESSION IS HIGHLY DYNAMIC AND COMPLEX, GROWING EVIDENCE SUGGESTS THE EXISTENCE OF ANOTHER HIGHER LEVEL OF REGULATORY MECHANISM INVOLVED IN MIRNA ACTIVITY - CIRCULAR RNAS (CIRCRNAS). CIRCRNAS REPRESENT NOVEL, UNIQUE CLASS OF ENDOGENOUS NCRNAS CONTROLLING THE EXPRESSION AND FUNCTION OF MIRNA. THEY ARE CALLED NATURAL MIRNA "SPONGES". ACCUMULATING EVIDENCE REVEALS CIRCRNAS ROLE IN PHYSIOLOGICAL AND PATHOLOGICAL PROCESSES INCLUDING CNS AND IMMUNE REGULATION. PREVIOUS STUDIES IMPLICATED MIRNAS IN REGULATION OF AUTOIMMUNE DEMYELINATION IN MS. MULTIPLE SCLEROSIS IS A CHRONIC NEUROLOGICAL INFLAMMATORY DEMYELINATING DISORDER OF THE CENTRAL NERVOUS SYSTEM. WHILE THE ETIOLOGY OF MS IS STILL NOT FULLY UNDERSTOOD, ACCUMULATING EVIDENCE SUGGESTS THAT IT IS A MULTIFACTORIAL ENTITY WITH SIGNIFICANT INVOLVEMENT OF AUTOIMMUNE PROCESSES. 2022 4 1021 26 CIRCULAR RNA AS AN EPIGENETIC REGULATOR IN CHRONIC LIVER DISEASES. CIRCULAR RNA (CIRCRNA) IS A TYPE OF NON-CODING RNA CHARACTERIZED BY A COVALENTLY CLOSED CONTINUOUS LOOP. CIRCRNA IS GENERATED BY PRE-MRNA THROUGH BACK-SPLICING AND IS PROBABLY CLEARED UP BY EXTRACELLULAR VESICLES. CIRCRNAS PLAY A PIVOTAL ROLE IN THE EPIGENETIC REGULATION OF GENE EXPRESSION AT TRANSCRIPTIONAL AND POST-TRANSCRIPTIONAL LEVELS. RECENTLY, CIRCRNAS HAVE BEEN DEMONSTRATED TO BE INVOLVED IN THE REGULATION OF LIVER HOMEOSTASIS AND DISEASES. HOWEVER, THE EPIGENETIC ROLE AND UNDERLYING MECHANISMS OF CIRCRNAS IN CHRONIC LIVER DISEASES REMAIN UNCLEAR. THIS REVIEW DISCUSSED THE ROLE OF CIRCRNAS IN NON-NEOPLASTIC CHRONIC LIVER DISEASES, INCLUDING ALCOHOLIC LIVER DISEASE (ALD), METABOLIC-ASSOCIATED FATTY LIVER DISEASE (MAFLD), VIRAL HEPATITIS, LIVER INJURY AND REGENERATION, LIVER CIRRHOSIS, AND AUTOIMMUNE LIVER DISEASE. THE REVIEW ALSO HIGHLIGHTED THAT FURTHER EFFORTS ARE URGENTLY NEEDED TO DEVELOP CIRCRNAS AS NOVEL DIAGNOSTICS AND THERAPEUTICS FOR CHRONIC LIVER DISEASES. 2021 5 4297 37 MICRORNA-1224 SPLICING CIRCULARRNA-FILIP1L IN AN AGO2-DEPENDENT MANNER REGULATES CHRONIC INFLAMMATORY PAIN VIA TARGETING UBR5. DYSFUNCTIONS OF GENE TRANSCRIPTION AND TRANSLATION IN THE NOCICEPTIVE PATHWAYS PLAY THE CRITICAL ROLE IN DEVELOPMENT AND MAINTENANCE OF CHRONIC PAIN. CIRCULAR RNAS (CIRCRNAS) ARE EMERGING AS NEW PLAYERS IN REGULATION OF GENE EXPRESSION, BUT WHETHER AND HOW CIRCRNAS ARE INVOLVED IN CHRONIC PAIN REMAIN ELUSIVE. WE SHOWED HERE THAT COMPLETE FREUND'S ADJUVANT-INDUCED CHRONIC INFLAMMATION PAIN SIGNIFICANTLY INCREASED CIRCRNA-FILIP1L (FILAMIN A INTERACTING PROTEIN 1-LIKE) EXPRESSION IN SPINAL NEURONS OF MICE. BLOCKAGE OF THIS INCREASE ATTENUATED COMPLETE FREUND'S ADJUVANT-INDUCED NOCICEPTIVE BEHAVIORS, AND OVEREXPRESSION OF SPINAL CIRCRNA-FILIP1L IN NAIVE MICE MIMICKED THE NOCICEPTIVE BEHAVIORS AS EVIDENCED BY DECREASED THERMAL AND MECHANICAL NOCICEPTIVE THRESHOLD. FURTHERMORE, WE FOUND THAT MATURE CIRCRNA-FILIP1L EXPRESSION WAS NEGATIVELY REGULATED BY MIRNA-1224 VIA BINDING AND SPLICING OF PRECURSOR OF CIRCRNA-FILIP1L (PRE-CIRCRNA-FILIP1L) IN THE ARGONAUTE-2 (AGO2)-DEPENDENT MANNER. INCREASE OF SPINAL CIRCRNA-FILIP1L EXPRESSION RESULTED FROM THE DECREASE OF MIRNA-1224 EXPRESSION UNDER CHRONIC INFLAMMATION PAIN STATE. MIRNA-1224 KNOCKDOWN OR AGO2 OVEREXPRESSION INDUCED NOCICEPTIVE BEHAVIORS IN NAIVE MICE, WHICH WAS PREVENTED BY THE KNOCKDOWN OF SPINAL CIRCRNA-FILIP1L. FINALLY, WE DEMONSTRATED THAT A UBIQUITIN PROTEIN LIGASE E3 COMPONENT N-RECOGNIN 5 (UBR5), VALIDATED AS A TARGET OF CIRCRNA-FILIP1L, PLAYS A PIVOTAL ROLE IN REGULATION OF NOCICEPTION BY SPINAL CIRCRNA-FILIP1L. THESE DATA SUGGEST THAT MIRNA-1224-MEDIATED AND AGO2-DEPENDENT MODULATION OF SPINAL CIRCRNA-FILIP1L EXPRESSION REGULATES NOCICEPTION VIA TARGETING UBR5, REVEALING A NOVEL EPIGENETIC MECHANISM OF INTERACTION BETWEEN MIRNA AND CIRCRNA IN CHRONIC INFLAMMATION PAIN.SIGNIFICANCE STATEMENT CIRCRNAS ARE EMERGING AS NEW PLAYERS IN REGULATION OF GENE EXPRESSION. HERE, WE FOUND THAT THE INCREASE OF CIRCRNA-FILIP1L MEDIATED BY MIRNA-1224 IN AN AGO2-DEPENDENT WAY IN THE SPINAL CORD IS INVOLVED IN REGULATION OF NOCICEPTION VIA TARGETING UBR5 OUR STUDY REVEALS A NOVEL EPIGENETIC MECHANISM OF INTERACTION BETWEEN MIRNA AND CIRCRNA IN CHRONIC INFLAMMATION PAIN. 2019 6 1020 27 CIRCRNAS IN ATHEROSCLEROSIS, WITH SPECIAL EMPHASIS ON THE SPONGY EFFECT OF CIRCRNAS ON MIRNAS. ATHEROSCLEROSIS (AS) IS A CHRONIC INFLAMMATORY DISEASE, WHICH LEADS TO ATHEROSCLEROTIC RUPTURE, LUMEN STENOSIS AND THROMBOSIS, AND OFTEN ENDANGERS LIFE. CIRCULAR RNAS (CIRCRNAS) ARE A SPECIAL CLASS OF NON-CODING RNA MOLECULES, WHOSE ABNORMAL EXPRESSION HAS BEEN PROVED TO BE CLOSELY RELATED TO HUMAN DISEASES, INCLUDING AS. BOTH THE ABNORMAL REGULATION OF CIRCRNAS AND THE SPONGING EFFECT ON MIRNAS WOULD LEAD TO CHANGES IN GENE EXPRESSION IN THE FORM OF EPIGENETIC MODIFICATION, ULTIMATELY LEADING TO THE FORMATION OF AS. CIRCRNAS CAN BE USED AS PERIPHERAL BLOOD MARKERS OF AS, AND PLAY AN IMPORTANT REGULATORY ROLE IN THE PROLIFERATION, MIGRATION, INFLAMMATION AND APOPTOSIS OF VASCULAR SMOOTH MUSCLE CELLS, ENDOTHELIAL CELLS AND MACROPHAGE, WHICH ARE KEY CELLS FOR THE DEVELOPMENT OF AS. THE IN-DEPTH UNDERSTANDING OF CIRCRNAS IN AS NOT ONLY PROVIDES A NEW METHOD FOR THE DIAGNOSIS OF AS, BUT ALSO PROVIDES A NEW IDEA FOR THE TREATMENT OF AS. 2023 7 5716 44 SIRT6 PROTECTS VASCULAR SMOOTH MUSCLE CELLS FROM OSTEOGENIC TRANSDIFFERENTIATION VIA RUNX2 IN CHRONIC KIDNEY DISEASE. VASCULAR CALCIFICATION (VC) IS REGARDED AS AN IMPORTANT PATHOLOGICAL CHANGE LACKING EFFECTIVE TREATMENT AND ASSOCIATED WITH HIGH MORTALITY. SIRTUIN 6 (SIRT6) IS A MEMBER OF THE SIRTUIN FAMILY, A CLASS III HISTONE DEACETYLASE AND A KEY EPIGENETIC REGULATOR. SIRT6 HAS A PROTECTIVE ROLE IN PATIENTS WITH CHRONIC KIDNEY DISEASE (CKD). HOWEVER, THE EXACT ROLE AND MOLECULAR MECHANISM OF SIRT6 IN VC IN PATIENTS WITH CKD REMAIN UNCLEAR. HERE, WE DEMONSTRATED THAT SIRT6 WAS MARKEDLY DOWNREGULATED IN PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMCS) AND IN THE RADIAL ARTERY TISSUE OF PATIENTS WITH CKD WITH VC. SIRT6-TRANSGENIC (SIRT6-TG) MICE SHOWED ALLEVIATED VC, WHILE VASCULAR SMOOTH MUSCLE CELL-SPECIFIC (VSMC-SPECIFIC) SIRT6 KNOCKED-DOWN MICE SHOWED SEVERE VC IN CKD. SIRT6 SUPPRESSED THE OSTEOGENIC TRANSDIFFERENTIATION OF VSMCS VIA REGULATION OF RUNT-RELATED TRANSCRIPTION FACTOR 2 (RUNX2). COIMMUNOPRECIPITATION (CO-IP) AND IMMUNOPRECIPITATION (IP) ASSAYS CONFIRMED THAT SIRT6 BOUND TO RUNX2. MOREOVER, RUNX2 WAS DEACETYLATED BY SIRT6 AND FURTHER PROMOTED NUCLEAR EXPORT VIA EXPORTIN 1 (XPO1), WHICH IN TURN CAUSED DEGRADATION OF RUNX2 THROUGH THE UBIQUITIN-PROTEASOME SYSTEM. THESE RESULTS DEMONSTRATED THAT SIRT6 PREVENTED VC BY SUPPRESSING THE OSTEOGENIC TRANSDIFFERENTIATION OF VSMCS, AND AS SUCH TARGETING SIRT6 MAY BE AN APPEALING THERAPEUTIC TARGET FOR VC IN CKD. 2022 8 5120 29 POSSIBLE EPIGENETIC REGULATORY EFFECT OF DYSREGULATED CIRCULAR RNAS IN EPILEPSY. CIRCULAR RNAS (CIRCRNAS) INVOLVE IN THE EPIGENETIC REGULATION AND ITS MAJOR MECHANISM IS THE SEQUESTRATION OF THE TARGET MICRO RNAS (MIRNAS). WE HYPOTHESIZED THAT CIRCRNAS MIGHT BE RELATED WITH THE PATHOPHYSIOLOGY OF CHRONIC EPILEPSY AND EVALUATED THE ALTERED CIRCRNA EXPRESSIONS AND THEIR POSSIBLE REGULATORY EFFECTS ON THEIR TARGET MIRNAS AND MRNAS IN A MOUSE EPILEPSY MODEL. THE CIRCRNA EXPRESSION PROFILE IN THE HIPPOCAMPUS OF THE PILOCARPINE MICE WAS ANALYZED AND COMPARED WITH CONTROL. THE CORRELATION BETWEEN THE EXPRESSION OF MIRNA BINDING SITES (MIRNA RESPONSE ELEMENTS, MRE) IN THE DYSREGULATED CIRCRNAS AND THE EXPRESSION OF THEIR TARGET MIRNAS WAS EVALUATED. AS MIRNAS ALSO INHIBIT THEIR TARGET MRNAS, CIRCRNA-MIRNA-MRNA REGULATORY NETWORK, COMPRISED OF DYSREGULATED RNAS THAT TARGETS ONE ANOTHER WERE SEARCHED. FOR THE IDENTIFIED NETWORKS, BIOINFORMATICS ANALYSES WERE PERFORMED. AS THE RESULT, FORTY-THREE CIRCRNAS WERE DYSREGULATED IN THE HIPPOCAMPUS (UP-REGULATED, 26; DOWN-REGULATED, 17). THE CHANGE IN THE EXPRESSION OF MRE IN THOSE CIRCRNAS NEGATIVELY CORRELATED WITH THE CHANGE IN THE RELEVANT TARGET MIRNA EXPRESSION (R = -0.461, P<0.001), SUPPORTING THAT CIRCRNAS INHIBIT THEIR TARGET MIRNA. 333 DYSREGULATED CIRCRNA-MIRNA-MRNA NETWORKS WERE IDENTIFIED. GENE ONTOLOGY AND PATHWAY ANALYSES DEMONSTRATED THAT THE UP-REGULATED MRNAS IN THOSE NETWORKS WERE CLOSELY RELATED TO THE MAJOR PROCESSES IN EPILEPSY. AMONG THEM, STRING ANALYSIS IDENTIFIED 37 KEY MRNAS WITH ABUNDANT (>/=4) INTERACTIONS WITH OTHER DYSREGULATED TARGET MRNAS. THE DYSREGULATION OF THE CIRCRNAS WHICH HAD MULTIPLE INTERACTIONS WITH KEY MRNAS WERE VALIDATED BY PCR. WE CONCLUDED THAT DYSREGULATED CIRCRNAS MIGHT HAVE A PATHOPHYSIOLOGIC ROLE IN CHRONIC EPILEPSY BY REGULATING MULTIPLE DISEASE RELEVANT MRNAS VIA CIRCRNA-MIRNA-MRNA INTERACTIONS. 2018 9 4721 21 NONCODING RNAS IN MULTIPLE SCLEROSIS. MULTIPLE SCLEROSIS (MS), A CHRONIC INFLAMMATORY DEMYELINATING DISEASE OF THE CENTRAL NERVOUS SYSTEM, IS CHARACTERIZED BY AXONAL DEGENERATION AND GLIOSIS. ALTHOUGH THE CAUSES OF MS REMAIN UNKNOWN, GENE DYSREGULATION IN THE CENTRAL NERVOUS SYSTEM HAS BEEN ASSOCIATED WITH THE DISEASE PATHOGENESIS. AS SUCH, THE VARIOUS REGULATORS OF GENE EXPRESSION MAY BE CONTRIBUTING FACTORS. THE NONCODING (NC) RNAS HAVE PIQUED THE INTEREST OF MS RESEARCHERS DUE TO THEIR KNOWN FUNCTIONS IN HUMAN PHYSIOLOGY AND VARIOUS PATHOLOGICAL PROCESSES, DESPITE BEING GENERALLY CHARACTERIZED AS TRANSCRIPTS WITHOUT APPARENT PROTEIN-CODING CAPACITY. ACCUMULATING EVIDENCE HAS INDICATED THAT NCRNAS PARTICIPATE IN THE REGULATION OF MS BY ACTING AS EPIGENETIC FACTORS, ESPECIALLY THE LONG (L) NCRNAS AND THE MICRO (MI) RNAS, AND THEY ARE NOW RECOGNIZED AS KEY REGULATORY MOLECULES IN MS. IN THIS REVIEW, WE SUMMARIZE THE MOST CURRENT STUDIES ON THE CONTRIBUTION OF NCRNAS IN MS PATHOGENIC PROCESSES AND DISCUSS THEIR POTENTIAL APPLICATIONS IN THE DIAGNOSIS AND TREATMENT OF MS. 2018 10 1051 26 CLINICAL IMPLICATIONS OF EXOSOME-DERIVED NONCODING RNAS IN LIVER. EXOSOMES, ONE OF THREE MAIN TYPES OF EXTRACELLULAR VESICLES, ARE ~30-100 NM IN DIAMETER AND HAVE A LIPID BILAYER MEMBRANE. THEY ARE WIDELY DISTRIBUTED IN ALMOST ALL BODY FLUIDS. EXOSOMES HAVE THE POTENTIAL TO REGULATE UNKNOWN CELLULAR AND MOLECULAR MECHANISMS IN INTERCELLULAR COMMUNICATION, ORGAN HOMEOSTASIS, AND DISEASES. THEY ARE CRITICAL SIGNAL CARRIERS THAT TRANSFER NUCLEIC ACIDS, PROTEINS, LIPIDS, AND OTHER SUBSTANCES INTO RECIPIENT CELLS, PARTICIPATING IN CELLULAR SIGNAL TRANSDUCTION AND MATERIAL EXCHANGE. NCRNAS ARE NON-PROTEIN-CODING GENES THAT ACCOUNT FOR OVER 90% OF THE GENOME AND INCLUDE MICRORNAS (MIRNAS), LONG NCRNAS (LNCRNAS), AND CIRCULAR RNAS (CIRCRNAS). NCRNAS ARE CRUCIAL FOR PHYSIOLOGICAL AND PATHOLOGICAL ACTIVITIES IN THE LIVER BY PARTICIPATING IN GENE TRANSCRIPTION, POSTTRANSCRIPTIONAL EPIGENETIC REGULATION, AND CELLULAR PROCESSES THROUGH INTERACTING WITH DNA, RNA, OR PROTEINS. RECENT EVIDENCE FROM BOTH CLINICAL AND PRECLINICAL STUDIES INDICATES THAT EXOSOME-DERIVED NONCODING RNAS (NCRNAS) ARE HIGHLY INVOLVED IN THE PROGRESSION OF ACUTE AND CHRONIC LIVER DISEASES BY REGULATING HEPATIC LIPID METABOLISM, INNATE IMMUNITY, VIRAL INFECTION, FIBROSIS, AND CANCER. THEREFORE, EXOSOME-DERIVED NCRNAS HAVE PROMISING POTENTIAL AND CLINICAL IMPLICATIONS FOR THE EARLY DIAGNOSIS, TARGETED THERAPY, AND PROGNOSIS OF LIVER DISEASES. 2022 11 3504 33 IDENTIFICATION OF POTENTIALLY FUNCTIONAL CIRCRNAS AND PREDICTION OF CIRCRNA-MIRNA-MRNA REGULATORY NETWORK IN PERIODONTITIS: BRIDGING THE GAP BETWEEN BIOINFORMATICS AND CLINICAL NEEDS. BACKGROUND AND OBJECTIVE: PERIODONTITIS IS A MULTIFACTORIAL CHRONIC INFLAMMATORY DISEASE THAT CAN LEAD TO THE IRREVERSIBLE DESTRUCTION OF DENTAL SUPPORT TISSUES. AS AN EPIGENETIC FACTOR, THE EXPRESSION OF CIRCRNA IS TISSUE-DEPENDENT AND DISEASE-DEPENDENT. THIS STUDY AIMED TO IDENTIFY NOVEL PERIODONTITIS-ASSOCIATED CIRCRNAS AND PREDICT RELEVANT CIRCRNA-PERIODONTITIS REGULATORY NETWORK BY USING RECENTLY DEVELOPED BIOINFORMATIC TOOLS AND INTEGRATING SEQUENCING PROFILING WITH CLINICAL INFORMATION FOR GETTING A BETTER AND MORE THOROUGH IMAGE OF PERIODONTITIS PATHOGENESIS, FROM GENE TO CLINIC. MATERIAL AND METHODS: HIGH-THROUGHPUT SEQUENCING AND RT-QPCR WERE CONDUCTED TO IDENTIFY DIFFERENTIALLY EXPRESSED CIRCRNAS IN GINGIVAL TISSUES FROM PERIODONTITIS PATIENTS. THE RELATIONSHIP BETWEEN UPREGULATED CIRCRNAS EXPRESSION AND PROBING DEPTH (PD) WAS PERFORMED USING SPEARMAN'S CORRELATION ANALYSIS. BIOINFORMATIC ANALYSES INCLUDING GO ANALYSIS, CIRCRNA-DISEASE ASSOCIATION PREDICTION, AND CIRCRNA-MIRNA-MRNA NETWORK PREDICTION WERE PERFORMED TO CLARIFY POTENTIAL REGULATORY FUNCTIONS OF IDENTIFIED CIRCRNAS IN PERIODONTITIS. A RECEIVER-OPERATING CHARACTERISTIC (ROC) CURVE WAS ESTABLISHED TO ASSESS THE DIAGNOSTIC SIGNIFICANCE OF IDENTIFIED CIRCRNAS. RESULTS: HIGH-THROUGHPUT SEQUENCING IDENTIFIED 70 DIFFERENTIALLY EXPRESSED CIRCRNAS (68 UPREGULATED AND 2 DOWNREGULATED CIRCRNAS) IN HUMAN PERIODONTITIS (FOLD CHANGE >2.0 AND P < .05). THE TOP FIVE UPREGULATED CIRCRNAS WERE VALIDATED BY RT-QPCR THAT HAD STRONG ASSOCIATIONS WITH MULTIPLE HUMAN DISEASES, INCLUDING PERIODONTITIS. THE UPREGULATION OF CIRCRNAS WERE POSITIVELY CORRELATED WITH PD (R = .40-.69, P < .05, MODERATE). A CIRCRNA-MIRNA-MRNA NETWORK WITH THE TOP FIVE UPREGULATED CIRCRNAS, DIFFERENTIALLY EXPRESSED MRNAS, AND OVERLAPPED PREDICTED MIRNAS INDICATED POTENTIAL ROLES OF CIRCRNAS IN IMMUNE RESPONSE, CELL APOPTOSIS, MIGRATION, ADHESION, AND REACTION TO OXIDATIVE STRESS. THE ROC CURVE SHOWED THAT CIRCRNAS HAD POTENTIAL VALUE IN PERIODONTITIS DIAGNOSIS (AUC = 0.7321-0.8667, P < .05). CONCLUSION: CIRCRNA-DISEASE ASSOCIATIONS WERE PREDICTED BY ONLINE BIOINFORMATIC TOOLS. POSITIVE CORRELATION BETWEEN UPREGULATED CIRCRNAS, CIRCPTP4A2, CHR22:23101560-23135351+, CIRCARHGEF28, CIRCBARD1 AND CIRCRASA2, AND PD SUGGESTED FUNCTION OF CIRCRNAS IN PERIODONTITIS. NETWORK PREDICTION FURTHER FOCUSED ON DOWNSTREAM TARGETS REGULATED BY CIRCRNAS DURING PERIODONTITIS PATHOGENESIS. 2022 12 5596 31 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 13 1059 15 CLINICAL PERSPECTIVES OF NON-CODING RNA IN ORAL INFLAMMATORY DISEASES AND NEUROPATHIC PAIN: A NARRATIVE REVIEW. NON-CODING RNAS (NCRNAS) REPRESENT A RESEARCH HOTSPOT BY PLAYING A KEY ROLE IN EPIGENETIC AND TRANSCRIPTIONAL REGULATION OF DIVERSE BIOLOGICAL FUNCTIONS AND DUE TO THEIR INVOLVEMENT IN DIFFERENT DISEASES, INCLUDING ORAL INFLAMMATORY DISEASES. BASED ON NCRNAS' SUITABILITY FOR SALIVARY BIOMARKERS AND THEIR INVOLVEMENT IN NEUROPATHIC PAIN AND TISSUE REGENERATION SIGNALING PATHWAYS, THE PRESENT NARRATIVE REVIEW AIMS TO HIGHLIGHT THE POTENTIAL CLINICAL APPLICATIONS OF NCRNAS IN ORAL INFLAMMATORY DISEASES, WITH AN EMPHASIS ON SALIVARY DIAGNOSTICS, REGENERATIVE DENTISTRY, AND PRECISION MEDICINE FOR NEUROPATHIC OROFACIAL PAIN. 2022 14 4583 21 N6-METHYLADENINE RNA METHYLATION EPIGENETIC MODIFICATION AND KIDNEY DISEASES. RNA METHYLATION MODIFICATION IS A RAPIDLY DEVELOPING FIELD IN EPIGENETICS. N6-METHYLADENSINE (M(6)A) IS THE MOST COMMON INTERNAL MODIFICATION IN EUKARYOTIC MRNA. M(6)A GROUP REGULATES RNA SPLICING, STABILITY, TRANSLOCATION, AND TRANSLATION. ENZYMES CATALYZING THIS PROCESS WERE TERMED AS WRITERS, ERASERS, AND READERS. RECENT STUDIES HAVE FOCUSED ON EXPLORING THE ROLE OF RNA METHYLATION IN HUMAN DISEASES. RNA METHYLATION MODIFICATIONS, PARTICULARLY M(6)A, PLAY IMPORTANT ROLES IN THE PATHOGENESIS OF KIDNEY DISEASES. IN THIS REVIEW, WE PROVIDE A BRIEF DESCRIPTION OF M(6)A AND SUMMARIZE THE IMPACT OF M(6)A ON ACUTE AND CHRONIC KIDNEY DISEASE (CKD) AND POSSIBLE FUTURE STUDY DIRECTIONS FOR THIS RESEARCH. 2023 15 2882 27 G-PROTEIN-COUPLED RECEPTOR GPR17 REGULATES OLIGODENDROCYTE DIFFERENTIATION IN RESPONSE TO LYSOLECITHIN-INDUCED DEMYELINATION. OLIGODENDROCYTES ARE THE MYELIN-PRODUCING CELLS OF THE CENTRAL NERVOUS SYSTEM (CNS). A VARIETY OF BRAIN DISORDERS FROM "CLASSICAL" DEMYELINATING DISEASES, SUCH AS MULTIPLE SCLEROSIS, STROKE, SCHIZOPHRENIA, DEPRESSION, DOWN SYNDROME AND AUTISM, ARE SHOWN MYELINATION DEFECTS. OLIGODENDROCYTE MYELINATION IS REGULATED BY A COMPLEX INTERPLAY OF INTRINSIC, EPIGENETIC AND EXTRINSIC FACTORS. GPR17 (G PROTEIN-COUPLED RECEPTOR 17) IS A G PROTEIN-COUPLED RECEPTOR, AND HAS BEEN IDENTIFIED TO BE A REGULATOR FOR OLIGODENDROCYTE DEVELOPMENT. HERE, WE DEMONSTRATE THAT THE ABSENCE OF GPR17 ENHANCES REMYELINATION IN VIVO WITH A TOXIN-INDUCED MODEL WHEREBY FOCAL DEMYELINATED LESIONS ARE GENERATED IN SPINAL CORD WHITE MATTER OF ADULT MICE BY LOCALIZED INJECTION OF LPC(L-A-LYSOPHOSPHATIDYLCHOLINE). THE INCREASED EXPRESSION OF THE ACTIVATED FORM OF ERK1/2 (PHOSPHO-ERK1/2) IN LESION AREAS SUGGESTED THE POTENTIAL ROLE OF ERK1/2 ACTIVITY ON THE GPR17-DEPENDENT MODULATION OF MYELINATION. THE ABSENCE OF GPR17 ENHANCES REMYELINATION IS CORRELATE WITH THE ACTIVATED ERK1/2 (PHOSPHO-ERK1/2).BEING A MEMBRANE RECEPTOR, GPR17 REPRESENTS AN IDEAL DRUGGABLE TARGET TO BE EXPLOITED FOR INNOVATIVE REGENERATIVE APPROACHES TO ACUTE AND CHRONIC CNS DISEASES. 2018 16 4368 38 MIRNA-DEPENDENT CD4(+) T CELL DIFFERENTIATION IN THE PATHOGENESIS OF MULTIPLE SCLEROSIS. MULTIPLE SCLEROSIS (MS) IS CHARACTERIZED BY MULTIFOCAL LESIONS, CHRONIC INFLAMMATORY CONDITION, AND DEGENERATIVE PROCESSES WITHIN THE CENTRAL NERVOUS SYSTEM (CNS) LEADING TO DEMYELINATION. THE MOST IMPORTANT CELLS INVOLVED IN ITS PATHOGENESIS ARE THOSE WHICH ARE CD4(+), PARTICULARLY PROINFLAMMATORY TH1/TH17 AND REGULATORY TREG. SIGNAL CASCADES ASSOCIATED WITH CD4(+) DIFFERENTIATION ARE REGULATED BY MICRORNAS (MIRNAS): SHORT, SINGLE-STRANDED RNAS, RESPONSIBLE FOR NEGATIVE REGULATION OF GENE EXPRESSION AT THE POSTTRANSCRIPTIONAL LEVEL. SEVERAL MIRNAS HAVE BEEN CONSISTENTLY REPORTED AS SHOWING DYSREGULATED EXPRESSION IN MS, AND THEIR EXPRESSION PATTERNS MAY BE ELEVATED OR DECREASED, DEPENDING ON THE FUNCTION OF SPECIFIC MIRNA IN THE IMMUNE SYSTEM. STUDIES IN MS PATIENTS INDICATE THAT, AMONG OTHERS, MIR-141, MIR-200A, MIR-155, MIR-223, AND MIR-326 ARE UPREGULATED, WHILE MIR-15B, MIR-20B, MIR-26A, AND MIR-30A ARE DOWNREGULATED. DYSREGULATION OF THESE MIRNAS MAY CONTRIBUTE TO THE IMBALANCE BETWEEN PRO- AND ANTI-INFLAMMATORY PROCESSES, SINCE THEIR TARGETS ARE ASSOCIATED WITH THE REGULATION OF TH1/TH17 AND TREG CELL DIFFERENTIATION. HIGHLY EXPRESSED MIRNAS CAN IN TURN SUPPRESS TRANSLATION OF KEY TH1/TH17 DIFFERENTIATION INHIBITORS. MIRNA DYSREGULATION MAY RESULT FROM THE IMPACT OF VARIOUS FACTORS AT EACH STAGE OF THEIR BIOGENESIS. IMMATURE MIRNA UNDERGOES MULTISTAGE TRANSCRIPTIONAL AND POSTTRANSCRIPTIONAL MODIFICATIONS; THEREFORE, ANY PROTEIN INVOLVED IN THE PROCESSING OF MIRNAS CAN POTENTIALLY LEAD TO DISTURBANCES IN THEIR EXPRESSION. EPIGENETIC MODIFICATIONS THAT HAVE A DIRECT IMPACT ON MIRNA GENE TRANSCRIPTION MAY ALSO PLAY AN IMPORTANT ROLE. 2021 17 5234 35 PROFILE ANALYSIS AND FUNCTIONAL MODELING IDENTIFY CIRCULAR RNAS IN NONALCOHOLIC FATTY LIVER DISEASE AS REGULATORS OF HEPATIC LIPID METABOLISM. NONALCOHOLIC FATTY LIVER DISEASE (NAFLD) IS THE LEADING CAUSE OF CHRONIC LIVER DISEASE, ASSOCIATED WITH AN OUTCOME OF HEPATIC FIBROSIS/CIRRHOSIS AND HEPATOCELLULAR CARCINOMA. HOWEVER, LIMITED EXPLORATION OF THE UNDERLYING MECHANISMS HINDERS ITS PREVENTION AND TREATMENT. TO INVESTIGATE THE MECHANISMS OF EPIGENETIC REGULATION IN NAFLD, THE EXPRESSION PROFILE OF CIRCULAR RNA (CIRCRNA) OF RODENTS IN WHICH NAFLD WAS INDUCED BY A HIGH-FAT, HIGH-CHOLESTEROL (HFHC) DIET WAS STUDIED. MODELING OF THE CIRCRNA-MICRORNA (MIRNA) -MRNA REGULATORY NETWORK REVEALED THE FUNCTIONAL CHARACTERISTICS OF NAFLD-SPECIFIC CIRCRNAS. THE TARGETS AND EFFECTS IN THE LIVER OF SUCH NAFLD-SPECIFIC CIRCRNAS WERE FURTHER ASSESSED. OUR RESULTS UNCOVERED THAT THE DOWNREGULATION OF 28 ANNOTATED CIRCRNAS CHARACTERIZES HFHC DIET-INDUCED NAFLD. AMONG THE DOWNREGULATED CIRCRNAS, LONG INTERGENIC NON-PROTEIN CODING RNA, P53 INDUCED TRANSCRIPT (LNCPINT) -DERIVED CIRCRNAS (CIRC_0001452, CIRC_0001453, AND CIRC_0001454) TARGETED BOTH MIR-466I-3P AND MIR-669C-3P. THEIR DEFICIENCY IN NAFLD ABROGATED THE CIRCRNA-BASED INHIBITORY EFFECT ON BOTH MIRNAS, WHICH FURTHER INACTIVATED THE AMPK SIGNALING PATHWAY VIA AMPK-ALPHA1 SUPPRESSION. INHIBITION OF THE AMPK SIGNALING PATHWAY PROMOTES HEPATIC STEATOSIS, DEPENDING ON THE TRANSCRIPTIONAL AND TRANSLATIONAL UPREGULATION OF LIPOGENIC GENES, SUCH AS THOSE ENCODING STEROL REGULATORY ELEMENT-BINDING PROTEIN 1 (SREBP1) AND FATTY ACID SYNTHASE (FASN) IN HEPATOCYTES. THE LEVELS OF LNCPINT-DERIVED CIRCRNAS DISPLAYED A NEGATIVE ASSOCIATION WITH HEPATIC TRIGLYCERIDE (TG) CONCENTRATION. THESE FINDINGS SUGGEST THAT LOSS OF LNCPINT-DERIVED CIRCRNAS MAY UNDERLIE NAFLD VIA MIR-466I-3P- AND MIR-669C-3P-DEPENDENT INACTIVATION OF THE AMPK SIGNALING PATHWAY. 2022 18 6396 33 THE ROLE OF THE MIR-148/-152 FAMILY IN PHYSIOLOGY AND DISEASE. MICRORNAS (MIRNAS) ARE ENDOGENOUSLY ENCODED APPROXIMATELY 22 NT SMALL NON-CODING RNAS. THEY FUNCTION AS KEY PLAYERS OF MANY CELLULAR PROCESSES BY BASE PAIRING WITH TARGET MRNAS AND THEREBY IMPAIRING GENE EXPRESSION AT THE POST-TRANSCRIPTIONAL LEVEL. RECENT FINDINGS DEMONSTRATE A CRITICAL ROLE OF MANY MIRNAS IN IMMUNE CELL DIFFERENTIATION AND IMMUNE RESPONSES, WHICH IS ALSO ASSOCIATED WITH THE DEVELOPMENT AND PROGRESSION OF MANY TUMOR AND NON-TUMOR DISEASES. HERE WE REVIEW THE MULTIFACETED MIRNA-148/-152 FAMILY MEMBERS CONSISTING OF MIR-148A, MIR-148B AND MIR-152. NEXT TO REGULATION MECHANISMS THAT CONTROL THE EXPRESSION OF THIS MIRNA FAMILY, WE WILL FOCUS ON (I) THE ROLE OF MIR-148A IN REGULATING B AND T LYMPHOCYTE FUNCTION AND ITS ROLE IN ASSOCIATED DISEASES AND (II) THE IMPORTANCE OF MIR-148/-152 FAMILY MEMBERS FOR CANCER INITIATION, TUMOR GROWTH AND METASTASIS FORMATION. IN ADDITION, THIS REVIEW AIMS TO HIGHLIGHT SOME SELECTED TARGETS OF THE MIRNA-148/-152 FAMILY MEMBERS, WHICH ARE INVOLVED IN THE BIOLOGY OF CANCER AND MAINTENANCE OF EPIGENETIC PATTERNS. IN CONCLUSION, MEMBERS OF THE MIR-148/-152 FAMILY MIGHT REPRESENT PROGNOSTIC MARKERS AND/OR POTENTIAL THERAPEUTIC TARGETS FOR TREATMENT OF AUTOIMMUNE DISORDERS, CHRONIC INFLAMMATORY DISEASES AND MULTIPLE TYPES OF CANCER. 2017 19 3752 29 INTEGRATED ANALYSIS OF CIRCRNAS AND MRNAS EXPRESSION PROFILE REVEALED THE INVOLVEMENT OF HSA_CIRC_0007919 IN THE PATHOGENESIS OF ULCERATIVE COLITIS. BACKGROUND: ULCERATIVE COLITIS (UC) IS CHARACTERIZED BY CHRONIC INFLAMMATION IN THE COLON AND EPIGENETIC FACTORS UNDERLYING THE OCCURRENCE. CIRCULAR RNAS (CIRCRNAS) HAVE BEEN UNDER INTENSIVE FOCUS DUE TO THE CIRCULAR CONSTRUCT AND GENE-REGULATING FUNCTIONS. HOWEVER, THE CHANGES AND ROLES OF CIRCRNAS IN UC REMAIN UNKNOWN. METHODS: MICROARRAYS WERE USED TO DETECT THE DIFFERENTIALLY EXPRESSED GENES, AND QUANTITATIVE REAL-TIME PCR WAS USED TO IDENTIFY THE CHANGES IN UC. IN SILICO ANALYSES WERE PERFORMED TO PREDICT THE FUNCTIONS OF CIRCRNAS AND MRNAS. IN VITRO, EPITHELIAL CELL LINES WERE STIMULATED BY PRO-INFLAMMATION EFFECTORS TO TEST THE ALTERATIONS IN CIRCRNAS. CIRCRNAS-MICRORNAS-MRNAS NETWORK CLARIFIED THE POTENTIAL MECHANISMS UNDERLYING CIRCRNAS IN UC. THE BINDING SITE BETWEEN HSA_CIRC_0007919 AND MIR-138 OR LET-7A WAS VERIFIED USING DUAL-LUCIFERASE ASSAY. RESULTS: A TOTAL OF 264 SIGNIFICANTLY DYSREGULATED CIRCRNAS AND 1869 DIFFERENTIALLY EXPRESSED MRNAS IN INFLAMED MUCOSA WERE COMPARED WITH THE NON-INFLAMED MUCOSA IN UC. HSA_CIRC_0004662 AND HSA_CIRC_0007919 WERE ALTERED LARGELY IN UC TISSUES. HSA_CIRC_0007919 WAS REDUCED PERSISTENTLY AFTER INFLAMMATORY TREATMENTS, AND IT WAS RELEVANT TO MAYO ENDOSCOPIC SUBSCORES AND THE EXPRESSION OF TIGHT JUNCTION MOLECULES. FINALLY, HSA_CIRC_0007919 COULD HARBOR MIR-138, AND LET-7A TO REGULATE THE TARGETED MRNAS EPC1 AND VIPR1. CONCLUSIONS: SEVERAL CIRCRNAS WERE DIFFERENTIALLY EXPRESSED IN UC. HSA_CIRC_0007919 IS RELATED TO CLINICAL CHARACTERISTICS AND EPITHELIAL INTEGRITY BY BINDING TO HSA-LET-7A, HSA-MIR-138 TO REGULATE THE TARGET GENES. CIRCRNAS, ESPECIALLY HSA_CIRC_0007919, ARE ASSOCIATED WITH THE PATHOGENESIS AND DEVELOPMENT OF UC, WITH POTENTIAL DIAGNOSTIC AND THERAPEUTIC IMPLICATIONS. 2019 20 1019 29 CIRCRNA-MIRNA CROSS-TALK IN THE TRANSITION FROM PAROXYSMAL TO PERMANENT ATRIAL FIBRILLATION. BACKGROUND: ATRIAL FIBRILLATION (AF) IS THE MOST PREVALENT CARDIAC ARRHYTHMIA IN WESTERN COUNTRIES. THE FACTORS GOVERNING THE PROGRESSION OF AF TO A PERMANENT CHRONIC CONDITION ARE STILL NOT WELL CHARACTERIZED. AMONG EPIGENETIC FACTORS, NON-CODING RNAS (NCRNAS) SUCH AS MIRNAS AND LNCRNAS HAVE BEEN RECENTLY DESCRIBED AS IMPORTANT PLAYERS INVOLVED IN THE AF PROGRESSION. WE HYPOTHESIZE ABOUT THE EXISTENCE OF ADDITIONAL REGULATORY LAYERS IN AF INVOLVING AN INTRICATE CROSS-TALK BETWEEN DIFFERENT NCRNA SPECIES, NAMELY MIRNAS AND CIRCRNAS FOR THE ESTABLISHMENT OF A CHRONIC AF CONDITION. METHODS AND RESULTS: WE HAVE PERFORMED AN UNBIASED STUDY ANALYZING THE EXPRESSION PROFILE FOR MIRNAS AND CIRCRNAS IN LEFT-ATRIAL BIOPSIES FROM PATIENTS WITH PAROXYSMAL AND PERMANENT AF BY RNA-SEQ. THE TRANSITION FROM PAROXYSMAL TO PERMANENT AF IS CHARACTERIZED BY A PATTERN OF DOWN-REGULATED MIRNAS, CONCOMITANT TO THE APPEARANCE OF SPECIFIC CIRCRNA SPECIES. THE ANALYSIS OF THE SPONGING ACTIVITIES OF THE CIRCRNAS EXCLUSIVELY EXPRESSED IN PERMANENT AF SAMPLES, ALLOWED US TO DETERMINE THAT THEY COULD BE RESPONSIBLE FOR THE DOWNREGULATION OF SPECIFIC MIRNAS IN ESTABLISHMENT OF A PERMANENT AF CONDITION. CONCLUSION: SPONGING ACTIVITY OF CIRCRNAS SEQUESTERING SPECIFIC MIRNAS IS AN IMPORTANT FACTOR TO BE CONSIDERED FOR THE DETERMINATION OF THE MOLECULAR MECHANISMS INVOLVED IN AF PROGRESSION. 2019