1 5600 130 ROLES OF VOLTAGE-DEPENDENT SODIUM CHANNELS IN NEURONAL DEVELOPMENT, PAIN, AND NEURODEGENERATION. BESIDES INITIATING AND PROPAGATING ACTION POTENTIALS IN ESTABLISHED NEURONAL CIRCUITS, VOLTAGE-DEPENDENT SODIUM CHANNELS SCULPT AND BOLSTER THE FUNCTIONAL NEURONAL NETWORK FROM EARLY IN EMBRYONIC DEVELOPMENT THROUGH ADULTHOOD (E.G., DIFFERENTIATION OF OLIGODENDROCYTE PRECURSOR CELLS INTO OLIGODENDROCYTES, MYELINATING AXON; COMPETITION BETWEEN NEIGHBORING EQUIPOTENTIAL NEURITES FOR DEVELOPMENT INTO A SINGLE AXON; ENHANCING AND OPPOSING FUNCTIONAL INTERACTIONS WITH ATTRACTIVE AND REPULSIVE MOLECULES FOR AXON PATHFINDING; EXTENDING AND RETRACTING TERMINAL ARBORIZATION OF AXON FOR CORRECT SYNAPSE FORMATION; EXPERIENCE-DRIVEN COGNITION; NEURONAL SURVIVAL; AND REMYELINATION OF DEMYELINATED AXONS). SURPRISINGLY, DIFFERENT PATTERNS OF ACTION POTENTIALS DIRECT HOMEOSTASIS-BASED EPIGENETIC SELECTION FOR NEUROTRANSMITTER PHENOTYPE, THUS EXCITABILITY BY SODIUM CHANNELS SPECIFYING EXPRESSION OF INHIBITORY NEUROTRANSMITTERS. MECHANISMS FOR THESE PLEIOTROPIC EFFECTS OF SODIUM CHANNELS INCLUDE RECIPROCAL INTERACTIONS BETWEEN NEURONS AND GLIA VIA NEUROTRANSMITTERS, GROWTH FACTORS, AND CYTOKINES AT SYNAPSES AND AXONS. SODIUM CHANNELOPATHIES CAUSING PAIN (E.G., ALLODYNIA) AND NEURODEGENERATION (E.G., MULTIPLE SCLEROSIS) DERIVE FROM 1) ELECTROPHYSIOLOGICAL DISTURBANCES BY INSULTS (E.G., ISCHEMIA/HYPOXIA, TOXINS, AND ANTIBODIES); 2) LOSS-OF-PHYSIOLOGICAL FUNCTION OR GAIN-OF-PATHOLOGICAL FUNCTION OF MUTANT SODIUM CHANNEL PROTEINS; 3) SPATIOTEMPORAL INAPPROPRIATE EXPRESSION OF NORMAL SODIUM CHANNEL PROTEINS; OR 4) DE-REPRESSED EXPRESSION OF OTHERWISE SILENT SODIUM CHANNEL GENES. NA(V)1.7 PROVED TO ACCOUNT FOR PAIN IN HUMAN ERYTHERMALGIA AND INFLAMMATION, BEING THE CONVINCING MOLECULAR TARGET OF PAIN TREATMENT. 2006 2 5408 32 REGULATION AND SIGNALING OF THE GPR17 RECEPTOR IN OLIGODENDROGLIAL CELLS. REMYELINATION, NAMELY, THE FORMATION OF NEW MYELIN SHEATHS AROUND DENUDED AXONS, COUNTERACTS AXONAL DEGENERATION AND RESTORES NEURONAL FUNCTION. CONSIDERABLE ADVANCES HAVE BEEN MADE IN UNDERSTANDING THIS REGENERATIVE PROCESS THAT OFTEN FAILS IN DISEASES LIKE MULTIPLE SCLEROSIS, LEAVING AXONS DEMYELINATED AND VULNERABLE TO DAMAGE, THUS CONTRIBUTING TO DISEASE PROGRESSION. THE IDENTIFICATION OF THE MEMBRANE RECEPTOR GPR17 ON A SUBSET OF OLIGODENDROCYTE PRECURSOR CELLS (OPCS), WHICH MEDIATE REMYELINATION IN THE ADULT CENTRAL NERVOUS SYSTEM (CNS), HAS LED TO A HUGE AMOUNT OF EVIDENCE THAT VALIDATED THIS RECEPTOR AS A NEW ATTRACTIVE TARGET FOR REMYELINATING THERAPIES. HERE, WE SUMMARIZE THE ROLE OF GPR17 IN OPC FUNCTION, MYELINATION AND REMYELINATION, DESCRIBING ITS ATYPICAL PHARMACOLOGY, ITS DOWNSTREAM SIGNALING, AND THE GENETIC AND EPIGENETIC FACTORS MODULATING ITS ACTIVITY. WE ALSO HIGHLIGHT CRUCIAL INSIGHTS INTO GPR17 PATHOPHYSIOLOGY COMING FROM THE DEMONSTRATION THAT OLIGODENDROCYTE INJURY, ASSOCIATED WITH INFLAMMATION IN CHRONIC NEURODEGENERATIVE CONDITIONS, IS INVARIABLY CHARACTERIZED BY ABNORMAL AND PERSISTENT GPR17 UPREGULATION, WHICH, IN TURN, IS ACCOMPANIED BY A BLOCK OF OPCS AT IMMATURE PREMYELINATING STAGES. FINALLY, WE DISCUSS THE CURRENT LITERATURE IN LIGHT OF THE POTENTIAL EXPLOITMENT OF GPR17 AS A THERAPEUTIC TARGET TO PROMOTE REMYELINATION. 2020 3 4304 26 MICRORNA-223 PROTECTS NEURONS FROM DEGENERATION IN EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS. MULTIPLE SCLEROSIS IS A CHRONIC INFLAMMATORY, DEMYELINATING, AND NEURODEGENERATIVE DISEASE AFFECTING THE BRAIN, SPINAL CORD AND OPTIC NERVES. NEURONAL DAMAGE IS TRIGGERED BY VARIOUS HARMFUL FACTORS THAT ENGAGE DIVERSE SIGNALLING CASCADES IN NEURONS; THUS, THERAPEUTIC APPROACHES TO PROTECT NEURONS WILL NEED TO FOCUS ON AGENTS THAT CAN TARGET MULTIPLE BIOLOGICAL PROCESSES. WE HAVE THEREFORE FOCUSED OUR ATTENTION ON MICRORNAS: SMALL NON-CODING RNAS THAT PRIMARILY FUNCTION AS POST-TRANSCRIPTIONAL REGULATORS THAT TARGET MESSENGER RNAS AND REPRESS THEIR TRANSLATION INTO PROTEINS. A SINGLE MICRORNA CAN TARGET MANY FUNCTIONALLY RELATED MESSENGER RNAS MAKING MICRORNAS POWERFUL EPIGENETIC REGULATORS. DYSREGULATION OF MICRORNAS HAS BEEN DESCRIBED IN MANY NEURODEGENERATIVE DISEASES INCLUDING MULTIPLE SCLEROSIS. HERE, WE REPORT THAT TWO MICRORNAS, MIR-223-3P AND MIR-27A-3P, ARE UPREGULATED IN NEURONS IN THE EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS MOUSE MODEL OF CNS INFLAMMATION AND IN GREY MATTER-CONTAINING MULTIPLE SCLEROSIS LESIONS. PRIOR WORK HAS SHOWN PERIPHERAL BLOOD MONONUCLEAR CELL CONDITIONED MEDIA CAUSES SUBLETHAL DEGENERATION OF NEURONS IN CULTURE. WE FIND OVEREXPRESSION OF MIR-27A-3P OR MIR-223-3P PROTECTS DISSOCIATED CORTICAL NEURONS FROM CONDITION MEDIA MEDIATED DEGENERATION. INTRODUCTION OF MIR-223-3P IN VIVO IN MOUSE RETINAL GANGLION CELLS PROTECTS THEIR AXONS FROM DEGENERATION IN EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS. IN SILICO ANALYSIS REVEALED THAT MESSENGER RNAS INVOLVED IN GLUTAMATE RECEPTOR SIGNALLING ARE ENRICHED AS MIR-27A-3P AND MIR-223-3P TARGETS. WE OBSERVE THAT ANTAGONISM OF NMDA AND AMPA TYPE GLUTAMATE RECEPTORS PROTECTS NEURONS FROM CONDITION MEDIA DEPENDENT DEGENERATION. OUR RESULTS SUGGEST THAT MIR-223-3P AND MIR-27A-3P ARE UPREGULATED IN RESPONSE TO INFLAMMATION TO MEDIATE A COMPENSATORY NEUROPROTECTIVE GENE EXPRESSION PROGRAM THAT DESENSITIZES NEURONS TO GLUTAMATE BY TARGETING MESSENGER RNAS INVOLVED IN GLUTAMATE RECEPTOR SIGNALLING. 2019 4 4758 32 NOVEL TREATMENT STRATEGIES TARGETING MYELIN AND OLIGODENDROCYTE DYSFUNCTION IN SCHIZOPHRENIA. OLIGODENDROCYTES ARE THE GLIAL CELLS RESPONSIBLE FOR THE FORMATION OF THE MYELIN SHEATH AROUND AXONS. DURING NEURODEVELOPMENT, OLIGODENDROCYTES UNDERGO MATURATION AND DIFFERENTIATION, AND LATER REMYELINATION IN ADULTHOOD. ABNORMALITIES IN THESE PROCESSES HAVE BEEN ASSOCIATED WITH BEHAVIORAL AND COGNITIVE DYSFUNCTIONS AND THE DEVELOPMENT OF VARIOUS MENTAL ILLNESSES LIKE SCHIZOPHRENIA. SEVERAL STUDIES HAVE IMPLICATED OLIGODENDROCYTE DYSFUNCTION AND MYELIN ABNORMALITIES IN THE DISORDER, TOGETHER WITH ALTERED EXPRESSION OF MYELIN-RELATED GENES SUCH AS OLIG2, CNP, AND NRG1. HOWEVER, THE MOLECULAR MECHANISMS SUBJACENT OF THESE ALTERATIONS REMAIN ELUSIVE. SCHIZOPHRENIA IS A SEVERE, CHRONIC PSYCHIATRIC DISORDER AFFECTING MORE THAN 23 MILLION INDIVIDUALS WORLDWIDE AND ITS SYMPTOMS USUALLY APPEAR AT THE BEGINNING OF ADULTHOOD. CURRENTLY, THE MAJOR THERAPEUTIC STRATEGY FOR SCHIZOPHRENIA RELIES ON THE USE OF ANTIPSYCHOTICS. DESPITE THEIR WIDESPREAD USE, THE EFFECTS OF ANTIPSYCHOTICS ON GLIAL CELLS, ESPECIALLY OLIGODENDROCYTES, REMAIN UNCLEAR. THUS, IN THIS REVIEW WE HIGHLIGHT THE CURRENT KNOWLEDGE REGARDING OLIGODENDROCYTE DYSFUNCTION IN SCHIZOPHRENIA, COMPILING DATA FROM (EPI)GENETIC STUDIES AND UP-TO-DATE MODELS TO INVESTIGATE THE ROLE OF OLIGODENDROCYTES IN THE DISORDER. IN ADDITION, WE EXAMINED POTENTIAL TARGETS CURRENTLY INVESTIGATED FOR THE IMPROVEMENT OF SCHIZOPHRENIA SYMPTOMS. RESEARCH IN THIS AREA HAS BEEN INVESTIGATING POTENTIAL BENEFICIAL COMPOUNDS, INCLUDING THE D-AMINO ACIDS D-ASPARTATE AND D-SERINE, THAT ACT AS NMDA RECEPTOR AGONISTS, MODULATING THE GLUTAMATERGIC SIGNALING; THE ANTIOXIDANT N-ACETYLCYSTEINE, A PRECURSOR IN THE SYNTHESIS OF GLUTATHIONE, PROTECTING AGAINST THE REDOX IMBALANCE; AS WELL AS LITHIUM, AN INHIBITOR OF GLYCOGEN SYNTHASE KINASE 3BETA (GSK3BETA) SIGNALING, CONTRIBUTING TO OLIGODENDROCYTE SURVIVAL AND FUNCTIONING. IN CONCLUSION, THERE IS STRONG EVIDENCE LINKING OLIGODENDROCYTE DYSFUNCTION TO THE DEVELOPMENT OF SCHIZOPHRENIA. HENCE, A BETTER UNDERSTANDING OF OLIGODENDROCYTE DIFFERENTIATION, AS WELL AS THE EFFECTS OF ANTIPSYCHOTIC MEDICATION IN THESE CELLS, COULD HAVE POTENTIAL IMPLICATIONS FOR UNDERSTANDING THE DEVELOPMENT OF SCHIZOPHRENIA AND FINDING NEW TARGETS FOR DRUG DEVELOPMENT. 2020 5 80 29 A NEW ROLE FOR THE P2Y-LIKE GPR17 RECEPTOR IN THE MODULATION OF MULTIPOTENCY OF OLIGODENDROCYTE PRECURSOR CELLS IN VITRO. OLIGODENDROCYTE PRECURSOR CELLS (OPCS, ALSO CALLED NG2 CELLS) ARE SCATTERED THROUGHOUT BRAIN PARENCHYMA, WHERE THEY FUNCTION AS A RESERVOIR TO REPLACE LOST OR DAMAGED OLIGODENDROCYTES, THE MYELIN-FORMING CELLS. THE HYPOTHESIS THAT, UNDER SOME CIRCUMSTANCES, OPCS CAN ACTUALLY BEHAVE AS MULTIPOTENT CELLS, THUS GENERATING ASTROCYTES AND NEURONS AS WELL, HAS ARISEN FROM SOME IN VITRO AND IN VIVO EVIDENCE, BUT THE MOLECULAR PATHWAYS CONTROLLING THIS ALTERNATIVE FATE OF OPCS ARE NOT FULLY UNDERSTOOD. THEIR IDENTIFICATION WOULD OPEN NEW OPPORTUNITIES FOR NEURONAL REPLACE STRATEGIES, BY FOSTERING THE INTRINSIC ABILITY OF THE BRAIN TO REGENERATE. HERE, WE SHOW THAT THE ANTI-EPILEPTIC EPIGENETIC MODULATOR VALPROIC ACID (VPA) CAN PROMOTE THE GENERATION OF NEW NEURONS FROM NG2(+) OPCS UNDER NEUROGENIC PROTOCOLS IN VITRO, THROUGH THEIR INITIAL DE-DIFFERENTIATION TO A STEM CELL-LIKE PHENOTYPE THAT THEN EVOLVES TO "HYBRID" CELL POPULATION, SHOWING OPC MORPHOLOGY BUT EXPRESSING THE NEURONAL MARKER BETAIII-TUBULIN AND THE GPR17 RECEPTOR, A KEY DETERMINANT IN DRIVING OPC TRANSITION TOWARDS MYELINATING OLIGODENDROCYTES. UNDER THESE CONDITIONS, THE PHARMACOLOGICAL BLOCKADE OF THE P2Y-LIKE RECEPTOR GPR17 BY CANGRELOR, A DRUG RECENTLY APPROVED FOR HUMAN USE, PARTIALLY MIMICS THE EFFECTS MEDIATED BY VPA THUS ACCELERATING CELLS' NEUROGENIC CONVERSION. THESE DATA SHOW A CO-LOCALIZATION BETWEEN NEURONAL MARKERS AND GPR17 IN VITRO, AND SUGGEST THAT, BESIDES ITS INVOLVEMENT IN OLIGODENDROGENESIS, GPR17 CAN DRIVE THE FATE OF NEURAL PRECURSOR CELLS BY INSTRUCTING PRECURSORS TOWARDS THE NEURONAL LINEAGE. BEING A MEMBRANE RECEPTOR, GPR17 REPRESENTS AN IDEAL "DRUGGABLE" TARGET TO BE EXPLOITED FOR INNOVATIVE REGENERATIVE APPROACHES TO ACUTE AND CHRONIC BRAIN DISEASES. 2016 6 4470 31 MOLECULAR NEUROPATHOLOGY OF ASTROCYTES AND OLIGODENDROCYTES IN ALCOHOL USE DISORDERS. POSTMORTEM STUDIES REVEAL STRUCTURAL AND MOLECULAR ALTERATIONS OF ASTROCYTES AND OLIGODENDROCYTES IN BOTH THE GRAY AND WHITE MATTER (GM AND WM) OF THE PREFRONTAL CORTEX (PFC) IN HUMAN SUBJECTS WITH CHRONIC ALCOHOL ABUSE OR DEPENDENCE. THESE GLIAL CELLULAR CHANGES APPEAR TO PARALLEL AND MAY LARGELY EXPLAIN STRUCTURAL AND FUNCTIONAL ALTERATIONS DETECTED USING NEUROIMAGING TECHNIQUES IN SUBJECTS WITH ALCOHOL USE DISORDERS (AUDS). MOREOVER, DUE TO THE CRUCIAL ROLES OF ASTROCYTES AND OLIGODENDROCYTES IN NEUROTRANSMISSION AND SIGNAL CONDUCTION, THESE CELLS ARE VERY LIKELY MAJOR PLAYERS IN THE MOLECULAR MECHANISMS UNDERPINNING ALCOHOLISM-RELATED CONNECTIVITY DISTURBANCES BETWEEN THE PFC AND RELEVANT INTERCONNECTING BRAIN REGIONS. THE GLIA-MEDIATED ETIOLOGY OF ALCOHOL-RELATED BRAIN DAMAGE IS LIKELY MULTIFACTORIAL SINCE METABOLIC, HORMONAL, HEPATIC AND HEMODYNAMIC FACTORS AS WELL AS DIRECT ACTIONS OF ETHANOL OR ITS METABOLITES HAVE THE POTENTIAL TO DISRUPT DISTINCT ASPECTS OF GLIAL NEUROBIOLOGY. STUDIES IN ANIMAL MODELS OF ALCOHOLISM AND POSTMORTEM HUMAN BRAINS HAVE IDENTIFIED ASTROCYTE MARKERS ALTERED IN RESPONSE TO SIGNIFICANT EXPOSURES TO ETHANOL OR DURING ALCOHOL WITHDRAWAL, SUCH AS GAP-JUNCTION PROTEINS, GLUTAMATE TRANSPORTERS OR ENZYMES RELATED TO GLUTAMATE AND GAMMA-AMINOBUTYRIC ACID (GABA) METABOLISM. CHANGES IN THESE PROTEINS AND THEIR REGULATORY PATHWAYS WOULD NOT ONLY CAUSE GM NEURONAL DYSFUNCTION, BUT ALSO DISTURBANCES IN THE ABILITY OF WM AXONS TO CONVEY IMPULSES. IN ADDITION, ALCOHOLISM ALTERS THE EXPRESSION OF ASTROCYTE AND MYELIN PROTEINS AND OF OLIGODENDROCYTE TRANSCRIPTION FACTORS IMPORTANT FOR THE MAINTENANCE AND PLASTICITY OF MYELIN SHEATHS IN WM AND GM. THESE CHANGES ARE CONCOMITANT WITH EPIGENETIC DNA AND HISTONE MODIFICATIONS AS WELL AS ALTERATIONS IN REGULATORY MICRORNAS (MIRNAS) THAT LIKELY CAUSE PROFOUND DISTURBANCES OF GENE EXPRESSION AND PROTEIN TRANSLATION. KNOWLEDGE IS ALSO AVAILABLE ABOUT INTERACTIONS BETWEEN ASTROCYTES AND OLIGODENDROCYTES NOT ONLY AT THE NODES OF RANVIER (NR), BUT ALSO IN GAP JUNCTION-BASED ASTROCYTE-OLIGODENDROCYTE CONTACTS AND OTHER FORMS OF CELL-TO-CELL COMMUNICATION NOW UNDERSTOOD TO BE CRITICAL FOR THE MAINTENANCE AND FORMATION OF MYELIN. CLOSE INTERACTIONS BETWEEN ASTROCYTES AND OLIGODENDROCYTES ALSO SUGGEST THAT THERAPIES FOR ALCOHOLISM BASED ON A SPECIFIC GLIAL CELL TYPE PATHOLOGY WILL REQUIRE A BETTER UNDERSTANDING OF MOLECULAR INTERACTIONS BETWEEN DIFFERENT CELL TYPES, AS WELL AS CONSIDERING THE POSSIBILITY OF USING COMBINED MOLECULAR APPROACHES FOR MORE EFFECTIVE THERAPIES. 2018 7 2882 25 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 8 5426 28 REGULATION OF SIRTUIN EXPRESSION IN AUTOIMMUNE NEUROINFLAMMATION: INDUCTION OF SIRT1 IN OLIGODENDROCYTE PROGENITOR CELLS. IN MULTIPLE SCLEROSIS (MS) REGENERATION OF OLIGODENDROCYTES FOLLOWING INFLAMMATORY DEMYELINATION IS LIMITED BY THE COMPROMISED ABILITY OF PROGENITORS TO REPOPULATE LESIONED AREAS AND TRANSITION TO FUNCTIONALLY COMPETENT OLIGODENDROCYTES. REGARDING UNDERLYING MECHANISMS, THE INVOLVEMENT OF EPIGENETIC PROCESSES HAS BEEN SUGGESTED, E.G. THE CONTRIBUTION OF HISTONE DEACETYLASES (HDAC) KNOWN TO REGULATE OLIGODENDROCYTE PROGENITOR CELL (OPC) DIFFERENTIATION. HOWEVER, THEIR PRECISE EXPRESSION PATTERNS, PARTICULAR OF REDOX-SENSITIVE NAD(+) HDACS, REMAINS LARGELY UNKNOWN. IN THIS STUDY, WE DETERMINED THE EXPRESSION AND ACTIVITY OF SIRTUINS, MEMBERS OF THE HDAC CLASS III FAMILY WITH A SPECIFIC FOCUS ON SIRT1, PREVIOUSLY ASSOCIATED WITH NEURODEGENERATIVE, INFLAMMATORY AND DEMYELINATING DISORDERS OF THE CENTRAL NERVOUS SYSTEM (CNS). BY INVESTIGATING MOUSE EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS (EAE), A MODEL FOR MS, WE FOUND THAT TRANSCRIPTION OF SIRT1, SIRT2 AND SIRT6 WAS SIGNIFICANTLY INCREASED IN THE CNS DURING CHRONIC DISEASE STAGES. WE CONFIRMED THIS FINDING FOR SIRT1 PROTEIN EXPRESSION AND WERE ABLE TO LOCALIZE UPREGULATED SIRT1 IN NUCLEI OF NG2(+) OR PDGFRALPHA(+) OPCS IN DEMYELINATED BRAIN LESIONS. IN CULTURED MOUSE A2B5(+) OPCS BLOCKADE OF SIRT1 ACTIVITY BY THE SMALL MOLECULE COMPOUND EX527 ENHANCED MITOTIC ACTIVITY BUT DID NOT AFFECT THE CAPACITY TO DIFFERENTIATE. A SIMILAR PATTERN WAS DETECTABLE IN OPCS DERIVED FROM SIRT1-DEFICIENT ANIMALS. TAKEN TOGETHER, OUR DATA SUGGEST THAT SIRT1 INHIBITION MAY HELP TO EXPAND THE ENDOGENOUS POOL OF OPCS WITHOUT AFFECTING THEIR DIFFERENTIATION. 2019 9 710 27 C-TERMINAL DOMAIN SMALL PHOSPHATASE 1 (CTDSP1) REGULATES GROWTH FACTOR EXPRESSION AND AXONAL REGENERATION IN PERIPHERAL NERVE TISSUE. PERIPHERAL NERVE INJURY (PNI) REPRESENTS A MAJOR CLINICAL AND ECONOMIC BURDEN. DESPITE THE ABILITY OF PERIPHERAL NEURONS TO REGENERATE THEIR AXONS AFTER AN INJURY, PATIENTS ARE OFTEN LEFT WITH MOTOR AND/OR SENSORY DISABILITY AND MAY DEVELOP CHRONIC PAIN. SUCCESSFUL REGENERATION AND TARGET ORGAN REINNERVATION REQUIRE COMPREHENSIVE TRANSCRIPTIONAL CHANGES IN BOTH INJURED NEURONS AND SUPPORT CELLS LOCATED AT THE SITE OF INJURY. THE EXPRESSION OF MOST OF THE GENES REQUIRED FOR AXON GROWTH AND GUIDANCE AND FOR SYNAPSIS FORMATION IS REPRESSED BY A SINGLE MASTER TRANSCRIPTIONAL REGULATOR, THE REPRESSOR ELEMENT 1 SILENCING TRANSCRIPTION FACTOR (REST). SUSTAINED INCREASE OF REST LEVELS AFTER INJURY INHIBITS AXON REGENERATION AND LEADS TO CHRONIC PAIN. AS TARGETING OF TRANSCRIPTION FACTORS IS CHALLENGING, WE TESTED WHETHER MODULATION OF REST ACTIVITY COULD BE ACHIEVED THROUGH KNOCKDOWN OF CARBOXY-TERMINAL DOMAIN SMALL PHOSPHATASE 1 (CTDSP1), THE ENZYME THAT STABILIZES REST BY PREVENTING ITS TARGETING TO THE PROTEASOME. TO TEST WHETHER KNOCKDOWN OF CTDSP1 PROMOTES NEUROTROPHIC FACTOR EXPRESSION IN BOTH SUPPORT CELLS LOCATED AT THE SITE OF INJURY AND IN PERIPHERAL NEURONS, WE TRANSFECTED MESENCHYMAL PROGENITOR CELLS (MPCS), A TYPE OF SUPPORT CELLS THAT ARE PRESENT AT HIGH CONCENTRATIONS AT THE SITE OF INJURY, AND DORSAL ROOT GANGLION (DRG) NEURONS WITH REST OR CTDSP1 SPECIFIC SIRNA. WE QUANTIFIED NEUROTROPHIC FACTOR EXPRESSION BY RT-QPCR AND WESTERN BLOT, AND BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) RELEASE IN THE CELL CULTURE MEDIUM BY ELISA, AND WE MEASURED NEURITE OUTGROWTH OF DRG NEURONS IN CULTURE. OUR RESULTS SHOW THAT CTDSP1 KNOCKDOWN PROMOTES NEUROTROPHIC FACTOR EXPRESSION IN BOTH DRG NEURONS AND THE SUPPORT CELLS MPCS, AND PROMOTES DRG NEURON REGENERATION. THERAPEUTICS TARGETING CTDSP1 ACTIVITY MAY, THEREFORE, REPRESENT A NOVEL EPIGENETIC STRATEGY TO PROMOTE PERIPHERAL NERVE REGENERATION AFTER PNI BY PROMOTING THE REGENERATIVE PROGRAM REPRESSED BY INJURY-INDUCED INCREASED LEVELS OF REST IN BOTH NEURONS AND SUPPORT CELLS. 2021 10 2772 37 EXTRACELLULAR ATP AND NEURODEGENERATION. ATP IS A POTENT SIGNALING MOLECULE ABUNDANTLY PRESENT IN THE CNS. IT ELICITS A WIDE ARRAY OF PHYSIOLOGICAL EFFECTS AND IS REGARDED AS THE PHYLOGENETICALLY MOST ANCIENT EPIGENETIC FACTOR PLAYING CRUCIAL BIOLOGICAL ROLES IN SEVERAL DIFFERENT TISSUES. THESE CAN RANGE FROM NEUROTRANSMISSION, SMOOTH MUSCLE CONTRACTION, CHEMOSENSORY SIGNALING, SECRETION AND VASODILATATION, TO MORE COMPLEX PHENOMENA SUCH AS IMMUNE RESPONSES, PAIN, MALE REPRODUCTION, FERTILIZATION AND EMBRYONIC DEVELOPMENT. ATP IS RELEASED INTO THE EXTRACELLULAR SPACE EITHER EXOCYTOTICALLY OR FROM DAMAGED AND DYING CELLS. IT IS OFTEN CO-RELEASED WITH OTHER NEUROTRANSMITTERS AND IT CAN INTERACT WITH GROWTH FACTORS AT BOTH RECEPTOR- AND/OR SIGNAL TRANSDUCTION-LEVEL. ONCE IN THE EXTRACELLULAR ENVIRONMENT, ATP BINDS TO SPECIFIC RECEPTORS TERMED P2. BASED ON PHARMACOLOGICAL PROFILES, ON SELECTIVITY OF COUPLING TO SECOND-MESSENGER PATHWAYS AND ON MOLECULAR CLONING, TWO MAIN SUBCLASSES WITH MULTIPLE SUBTYPES HAVE BEEN DISTINGUISHED. THEY ARE P2X, I.E. FAST CATION-SELECTIVE RECEPTOR CHANNELS (NA+, K+, CA2+), POSSESSING LOW AFFINITY FOR ATP AND RESPONSIBLE FOR FAST EXCITATORY NEUROTRANSMISSION, AND P2Y, I.E. SLOW G PROTEIN-COUPLED METABOTROPIC RECEPTORS, POSSESSING HIGHER AFFINITY FOR THE LIGAND. IN THE NERVOUS SYSTEM, THEY ARE BROADLY EXPRESSED IN BOTH NEURONS AND GLIAL CELLS AND CAN MEDIATE DUAL EFFECTS: SHORT-TERM SUCH AS NEUROTRANSMISSION, AND LONG-TERM SUCH AS TROPHIC ACTIONS. SINCE MASSIVE EXTRACELLULAR RELEASE OF ATP OFTEN OCCURS AFTER METABOLIC STRESS, BRAIN ISCHEMIA AND TRAUMA, PURINERGIC MECHANISMS ARE ALSO CORRELATED TO AND INVOLVED IN THE ETIOPATHOLOGY OF MANY NEURODEGENERATIVE CONDITIONS. FURTHERMORE, EXTRACELLULAR ATP PER SE IS TOXIC FOR PRIMARY NEURONAL DISSOCIATED AND ORGANOTYPIC CNS CULTURES FROM CORTEX, STRIATUM AND CEREBELLUM AND P2 RECEPTORS CAN MEDIATE AND AGGRAVATE HYPOXIC SIGNALING IN MANY CNS NEURONS. CONVERSELY, SEVERAL P2 RECEPTOR ANTAGONISTS ABOLISH THE CELL DEATH FATE OF PRIMARY NEURONAL CULTURES EXPOSED TO EXCESSIVE GLUTAMATE, SERUM/POTASSIUM DEPRIVATION, HYPOGLYCEMIA AND CHEMICAL HYPOXIA. IN PARALLEL WITH THESE DETRIMENTAL EFFECTS, ALSO TROPHIC FUNCTIONS HAVE BEEN EXTENSIVELY DESCRIBED FOR EXTRACELLULAR PURINES (BOTH FOR NEURONAL AND NON-NEURONAL CELLS), BUT THESE MIGHT EITHER AGGRAVATE OR AMELIORATE THE NORMAL CELLULAR CONDITIONS. IN SUMMARY, EXTRACELLULAR ATP PLAYS A VERY COMPLEX ROLE NOT ONLY IN THE REPAIR, REMODELING AND SURVIVAL OCCURRING IN THE NERVOUS SYSTEM, BUT EVEN IN CELL DEATH AND THIS CAN OCCUR EITHER AFTER NORMAL DEVELOPMENTAL CONDITIONS, AFTER INJURY, OR ACUTE AND CHRONIC DISEASES. 2003 11 2856 29 FROM METHYLATION TO MYELINATION: EPIGENOMIC AND TRANSCRIPTOMIC PROFILING OF CHRONIC INACTIVE DEMYELINATED MULTIPLE SCLEROSIS LESIONS. IN THE PROGRESSIVE PHASE OF MULTIPLE SCLEROSIS (MS), THE HAMPERED DIFFERENTIATION CAPACITY OF OLIGODENDROCYTE PRECURSOR CELLS (OPCS) EVENTUALLY RESULTS IN REMYELINATION FAILURE. WE HAVE PREVIOUSLY SHOWN THAT DNA METHYLATION OF ID2/ID4 IS HIGHLY INVOLVED IN OPC DIFFERENTIATION AND REMYELINATION. IN THIS STUDY, WE TOOK AN UNBIASED APPROACH BY DETERMINING GENOME-WIDE DNA METHYLATION PATTERNS WITHIN CHRONICALLY DEMYELINATED MS LESIONS AND INVESTIGATED HOW CERTAIN EPIGENETIC SIGNATURES RELATE TO OPC DIFFERENTIATION CAPACITY. WE COMPARED GENOME-WIDE DNA METHYLATION AND TRANSCRIPTIONAL PROFILES BETWEEN CHRONICALLY DEMYELINATED MS LESIONS AND MATCHED NORMAL-APPEARING WHITE MATTER (NAWM), MAKING USE OF POST-MORTEM BRAIN TISSUE (N = 9/GROUP). DNA METHYLATION DIFFERENCES THAT INVERSELY CORRELATED WITH MRNA EXPRESSION OF THEIR CORRESPONDING GENES WERE VALIDATED FOR THEIR CELL-TYPE SPECIFICITY IN LASER-CAPTURED OPCS USING PYROSEQUENCING. THE CRISPR-DCAS9-DNMT3A/TET1 SYSTEM WAS USED TO EPIGENETICALLY EDIT HUMAN-IPSC-DERIVED OLIGODENDROCYTES TO ASSESS THE EFFECT ON CELLULAR DIFFERENTIATION. OUR DATA SHOW HYPERMETHYLATION OF CPGS WITHIN GENES THAT CLUSTER IN GENE ONTOLOGIES RELATED TO MYELINATION AND AXON ENSHEATHMENT. CELL TYPE-SPECIFIC VALIDATION INDICATES A REGION-DEPENDENT HYPERMETHYLATION OF MBP, ENCODING FOR MYELIN BASIC PROTEIN, IN OPCS OBTAINED FROM WHITE MATTER LESIONS COMPARED TO NAWM-DERIVED OPCS. BY ALTERING THE DNA METHYLATION STATE OF SPECIFIC CPGS WITHIN THE PROMOTOR REGION OF MBP, USING EPIGENETIC EDITING, WE SHOW THAT CELLULAR DIFFERENTIATION AND MYELINATION CAN BE BIDIRECTIONALLY MANIPULATED USING THE CRISPR-DCAS9-DNMT3A/TET1 SYSTEM IN VITRO. OUR DATA INDICATE THAT OPCS WITHIN CHRONICALLY DEMYELINATED MS LESIONS ACQUIRE AN INHIBITORY PHENOTYPE, WHICH TRANSLATES INTO HYPERMETHYLATION OF CRUCIAL MYELINATION-RELATED GENES. ALTERING THE EPIGENETIC STATUS OF MBP CAN RESTORE THE DIFFERENTIATION CAPACITY OF OPCS AND POSSIBLY BOOST (RE)MYELINATION. 2023 12 6139 29 THE ETIOLOGICAL CONTRIBUTION OF GABAERGIC PLASTICITY TO THE PATHOGENESIS OF NEUROPATHIC PAIN. NEUROPATHIC PAIN DEVELOPING AFTER PERIPHERAL OR CENTRAL NERVE INJURY IS THE RESULT OF PATHOLOGICAL CHANGES GENERATED THROUGH COMPLEX MECHANISMS. DISRUPTION IN THE HOMEOSTASIS OF EXCITATORY AND INHIBITORY NEURONS WITHIN THE CENTRAL NERVOUS SYSTEM IS A CRUCIAL FACTOR IN THE FORMATION OF HYPERALGESIA OR ALLODYNIA OCCURRING WITH NEUROPATHIC PAIN. THE CENTRAL GABAERGIC PATHWAY HAS RECEIVED ATTENTION FOR ITS EXTENSIVE DISTRIBUTION AND FUNCTION IN NEURAL CIRCUITS, INCLUDING THE GENERATION AND DEVELOPMENT OF NEUROPATHIC PAIN. GABAERGIC INHIBITORY CHANGES THAT OCCUR IN THE INTERNEURONS ALONG DESCENDING MODULATORY AND NOCICEPTIVE PATHWAYS IN THE CENTRAL NERVOUS SYSTEM ARE BELIEVED TO GENERATE NEURONAL PLASTICITY, SUCH AS SYNAPTIC PLASTICITY OR FUNCTIONAL PLASTICITY OF THE RELATED GENES OR PROTEINS, THAT IS THE FOUNDATION OF PERSISTENT NEUROPATHIC PAIN. THE PRIMARY GABAERGIC PLASTICITY OBSERVED IN NEUROPATHIC PAIN INCLUDES GABAERGIC SYNAPSE HOMO- AND HETEROSYNAPTIC PLASTICITY, DECREASED SYNTHESIS OF GABA, DOWN-EXPRESSION OF GLUTAMIC ACID DECARBOXYLASE AND GABA TRANSPORTER, ABNORMAL EXPRESSION OF NKCC1 OR KCC2, AND DISTURBED FUNCTION OF GABA RECEPTORS. IN THIS REVIEW, WE DESCRIBE POSSIBLE MECHANISMS ASSOCIATED WITH GABAERGIC PLASTICITY, SUCH AS CENTRAL SENSITIZATION AND GABAERGIC INTERNEURON APOPTOSIS, AND THE EPIGENETIC ETIOLOGIES OF GABAERGIC PLASTICITY IN NEUROPATHIC PAIN. MOREOVER, WE SUMMARIZE POTENTIAL THERAPEUTIC TARGETS OF GABAERGIC PLASTICITY THAT MAY ALLOW FOR SUCCESSFUL RELIEF OF HYPERALGESIA FROM NERVE INJURY. FINALLY, WE COMPARE THE EFFECTS OF THE GABAERGIC SYSTEM IN NEUROPATHIC PAIN TO OTHER TYPES OF CHRONIC PAIN TO UNDERSTAND THE CONTRIBUTION OF GABAERGIC PLASTICITY TO NEUROPATHIC PAIN. 2019 13 533 28 ASTROCYTIC TRANSCRIPTION FACTOR REST UPREGULATES GLUTAMATE TRANSPORTER EAAT2, PROTECTING DOPAMINERGIC NEURONS FROM MANGANESE-INDUCED EXCITOTOXICITY. CHRONIC EXPOSURE TO HIGH LEVELS OF MANGANESE (MN) LEADS TO MANGANISM, A NEUROLOGICAL DISORDER WITH SIMILAR SYMPTOMS TO THOSE INHERENT TO PARKINSON'S DISEASE. HOWEVER, THE UNDERLYING MECHANISMS OF THIS PATHOLOGICAL CONDITION HAVE YET TO BE ESTABLISHED. SINCE THE HUMAN EXCITATORY AMINO ACID TRANSPORTER 2 (EAAT2) (GLUTAMATE TRANSPORTER 1 IN RODENTS) IS PREDOMINANTLY EXPRESSED IN ASTROCYTES AND ITS DYSREGULATION IS INVOLVED IN MN-INDUCED EXCITOTOXIC NEURONAL INJURY, CHARACTERIZATION OF THE MECHANISMS THAT MEDIATE THE MN-INDUCED IMPAIRMENT IN EAAT2 FUNCTION IS CRUCIAL FOR THE DEVELOPMENT OF NOVEL THERAPEUTICS AGAINST MN NEUROTOXICITY. REPRESSOR ELEMENT 1-SILENCING TRANSCRIPTION FACTOR (REST) EXERTS PROTECTIVE EFFECTS IN MANY NEURODEGENERATIVE DISEASES. BUT THE EFFECTS OF REST ON EAAT2 EXPRESSION AND ENSUING NEUROPROTECTION ARE UNKNOWN. GIVEN THAT THE EAAT2 PROMOTER CONTAINS REST BINDING SITES, THE PRESENT STUDY INVESTIGATED THE ROLE OF REST IN EAAT2 EXPRESSION AT THE TRANSCRIPTIONAL LEVEL IN ASTROCYTES AND MN-INDUCED NEUROTOXICITY IN AN ASTROCYTE-NEURON COCULTURE SYSTEM. THE RESULTS REVEAL THAT ASTROCYTIC REST POSITIVELY REGULATES EAAT2 EXPRESSION WITH THE RECRUITMENT OF AN EPIGENETIC MODIFIER, CAMP RESPONSE ELEMENT-BINDING PROTEIN-BINDING PROTEIN/P300, TO ITS CONSENSUS BINDING SITES IN THE EAAT2 PROMOTER. MOREOVER, ASTROCYTIC OVEREXPRESSION OF REST ATTENUATES MN-INDUCED REDUCTION IN EAAT2 EXPRESSION, LEADING TO ATTENUATION OF GLUTAMATE-INDUCED NEUROTOXICITY IN THE ASTROCYTE-NEURON COCULTURE SYSTEM. OUR FINDINGS DEMONSTRATE THAT ASTROCYTIC REST PLAYS A CRITICAL ROLE IN PROTECTION AGAINST MN-INDUCED NEUROTOXICITY BY ATTENUATING MN-INDUCED EAAT2 REPRESSION AND THE ENSUING EXCITOTOXIC DOPAMINERGIC NEURONAL INJURY. THIS INDICATES THAT ASTROCYTIC REST COULD BE A POTENTIAL MOLECULAR TARGET FOR THE TREATMENT OF MN TOXICITY AND OTHER NEUROLOGICAL DISORDERS ASSOCIATED WITH EAAT2 DYSREGULATION. 2021 14 3201 27 HDAC2 IN PRIMARY SENSORY NEURONS CONSTITUTIVELY RESTRAINS CHRONIC PAIN BY REPRESSING ALPHA2DELTA-1 EXPRESSION AND ASSOCIATED NMDA RECEPTOR ACTIVITY. ALPHA2DELTA-1 (ENCODED BY THE CACNA2D1 GENE) IS A NEWLY DISCOVERED NMDA RECEPTOR-INTERACTING PROTEIN AND IS THE THERAPEUTIC TARGET OF GABAPENTINOIDS (E.G., GABAPENTIN AND PREGABALIN) FREQUENTLY USED FOR TREATING PATIENTS WITH NEUROPATHIC PAIN. NERVE INJURY CAUSES SUSTAINED ALPHA2DELTA-1 UPREGULATION IN THE DORSAL ROOT GANGLION (DRG), WHICH PROMOTES NMDA RECEPTOR SYNAPTIC TRAFFICKING AND ACTIVATION IN THE SPINAL DORSAL HORN, A HALLMARK OF CHRONIC NEUROPATHIC PAIN. HOWEVER, LITTLE IS KNOWN ABOUT HOW NERVE INJURY INITIATES AND MAINTAINS THE HIGH EXPRESSION LEVEL OF ALPHA2DELTA-1 TO SUSTAIN CHRONIC PAIN. HERE, WE SHOW THAT NERVE INJURY CAUSED HISTONE HYPERACETYLATION AND DIMINISHED ENRICHMENT OF HISTONE DEACETYLASE-2 (HDAC2), BUT NOT HDAC3, AT THE CACNA2D1 PROMOTER IN THE DRG. STRIKINGLY, HDAC2 KNOCKDOWN OR CONDITIONAL KNOCKOUT IN DRG NEURONS IN MALE AND FEMALE MICE CONSISTENTLY INDUCED LONG-LASTING MECHANICAL PAIN HYPERSENSITIVITY, WHICH WAS READILY REVERSED BY BLOCKING NMDA RECEPTORS, INHIBITING ALPHA2DELTA-1 WITH GABAPENTIN OR DISRUPTING THE ALPHA2DELTA-1-NMDA RECEPTOR INTERACTION AT THE SPINAL CORD LEVEL. HDAC2 DELETION IN DRG NEURONS INCREASED HISTONE ACETYLATION LEVELS AT THE CACNA2D1 PROMOTER, UPREGULATED ALPHA2DELTA-1 IN THE DRG, AND POTENTIATED ALPHA2DELTA-1-DEPENDENT NMDA RECEPTOR ACTIVITY AT PRIMARY AFFERENT CENTRAL TERMINALS IN THE SPINAL DORSAL HORN. CORRESPONDINGLY, HDAC2 KNOCKDOWN-INDUCED PAIN HYPERSENSITIVITY WAS BLUNTED IN CACNA2D1 KNOCKOUT MICE. THUS, OUR FINDINGS REVEAL THAT HDAC2 FUNCTIONS AS A PIVOTAL TRANSCRIPTIONAL REPRESSOR OF NEUROPATHIC PAIN VIA CONSTITUTIVELY SUPPRESSING ALPHA2DELTA-1 EXPRESSION AND ENSUING PRESYNAPTIC NMDA RECEPTOR ACTIVITY IN THE SPINAL CORD. HDAC2 ENRICHMENT LEVELS AT THE CACNA2D1 PROMOTER IN DRG NEURONS CONSTITUTE A UNIQUE EPIGENETIC MECHANISM THAT GOVERNS ACUTE-TO-CHRONIC PAIN TRANSITION.SIGNIFICANCE STATEMENT EXCESS ALPHA2DELTA-1 PROTEINS PRODUCED AFTER NERVE INJURY DIRECTLY INTERACT WITH GLUTAMATE NMDA RECEPTORS TO POTENTIATE SYNAPTIC NMDA RECEPTOR ACTIVITY IN THE SPINAL CORD, A PROMINENT MECHANISM OF NERVE PAIN. BECAUSE ALPHA2DELTA-1 UPREGULATION AFTER NERVE INJURY IS LONG LASTING, GABAPENTINOIDS RELIEVE PAIN SYMPTOMS ONLY TEMPORARILY. OUR STUDY DEMONSTRATES FOR THE FIRST TIME THE UNEXPECTED ROLE OF INTRINSIC HDAC2 ACTIVITY AT THE ALPHA2DELTA-1 GENE PROMOTER IN LIMITING ALPHA2DELTA-1 GENE TRANSCRIPTION, NMDA RECEPTOR-DEPENDENT SYNAPTIC PLASTICITY, AND CHRONIC PAIN DEVELOPMENT AFTER NERVE INJURY. THESE FINDINGS CHALLENGE THE PREVAILING VIEW ABOUT THE ROLE OF GENERAL HDAC ACTIVITY IN PROMOTING CHRONIC PAIN. RESTORING THE REPRESSIVE HDAC2 FUNCTION AND/OR REDUCING HISTONE ACETYLATION AT THE ALPHA2DELTA-1 GENE PROMOTER IN PRIMARY SENSORY NEURONS COULD LEAD TO LONG-LASTING RELIEF OF NERVE PAIN. 2022 15 3968 30 LONG-LASTING ANALGESIA VIA TARGETED IN SITU REPRESSION OF NA(V)1.7 IN MICE. CURRENT TREATMENTS FOR CHRONIC PAIN RELY LARGELY ON OPIOIDS DESPITE THEIR SUBSTANTIAL SIDE EFFECTS AND RISK OF ADDICTION. GENETIC STUDIES HAVE IDENTIFIED IN HUMANS KEY TARGETS PIVOTAL TO NOCICEPTIVE PROCESSING. IN PARTICULAR, A HEREDITARY LOSS-OF-FUNCTION MUTATION IN NA(V)1.7, A SODIUM CHANNEL PROTEIN ASSOCIATED WITH SIGNALING IN NOCICEPTIVE SENSORY AFFERENTS, LEADS TO INSENSITIVITY TO PAIN WITHOUT OTHER NEURODEVELOPMENTAL ALTERATIONS. HOWEVER, THE HIGH SEQUENCE AND STRUCTURAL SIMILARITY BETWEEN NA(V) SUBTYPES HAS FRUSTRATED EFFORTS TO DEVELOP SELECTIVE INHIBITORS. HERE, WE INVESTIGATED TARGETED EPIGENETIC REPRESSION OF NA(V)1.7 IN PRIMARY AFFERENTS VIA EPIGENOME ENGINEERING APPROACHES BASED ON CLUSTERED REGULARLY INTERSPACED SHORT PALINDROMIC REPEATS (CRISPR)-DCAS9 AND ZINC FINGER PROTEINS AT THE SPINAL LEVEL AS A POTENTIAL TREATMENT FOR CHRONIC PAIN. TOWARD THIS END, WE FIRST OPTIMIZED THE EFFICIENCY OF NA(V)1.7 REPRESSION IN VITRO IN NEURO2A CELLS AND THEN, BY THE LUMBAR INTRATHECAL ROUTE, DELIVERED BOTH EPIGENOME ENGINEERING PLATFORMS VIA ADENO-ASSOCIATED VIRUSES (AAVS) TO ASSESS THEIR EFFECTS IN THREE MOUSE MODELS OF PAIN: CARRAGEENAN-INDUCED INFLAMMATORY PAIN, PACLITAXEL-INDUCED NEUROPATHIC PAIN, AND BZATP-INDUCED PAIN. OUR RESULTS SHOW EFFECTIVE REPRESSION OF NA(V)1.7 IN LUMBAR DORSAL ROOT GANGLIA, REDUCED THERMAL HYPERALGESIA IN THE INFLAMMATORY STATE, DECREASED TACTILE ALLODYNIA IN THE NEUROPATHIC STATE, AND NO CHANGES IN NORMAL MOTOR FUNCTION IN MICE. WE ANTICIPATE THAT THIS LONG-LASTING ANALGESIA VIA TARGETED IN VIVO EPIGENETIC REPRESSION OF NA(V)1.7 METHODOLOGY WE DUB PAIN LATER, MIGHT HAVE THERAPEUTIC POTENTIAL IN MANAGEMENT OF PERSISTENT PAIN STATES. 2021 16 6531 32 TRANSCRIPTIONAL REGULATION OF BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) BY METHYL CPG BINDING PROTEIN 2 (MECP2): A NOVEL MECHANISM FOR RE-MYELINATION AND/OR MYELIN REPAIR INVOLVED IN THE TREATMENT OF MULTIPLE SCLEROSIS (MS). MULTIPLE SCLEROSIS (MS) IS A CHRONIC PROGRESSIVE, NEUROLOGICAL DISEASE CHARACTERIZED BY THE TARGETED IMMUNE SYSTEM-MEDIATED DESTRUCTION OF CENTRAL NERVOUS SYSTEM (CNS) MYELIN. AUTOREACTIVE CD4+ T HELPER CELLS HAVE A KEY ROLE IN ORCHESTRATING MS-INDUCED MYELIN DAMAGE. ONCE ACTIVATED, CIRCULATING TH1-CELLS SECRETE A VARIETY OF INFLAMMATORY CYTOKINES THAT FOSTER THE BREAKDOWN OF BLOOD-BRAIN BARRIER (BBB) EVENTUALLY INFILTRATING INTO THE CNS. INSIDE THE CNS, THEY BECOME REACTIVATED UPON EXPOSURE TO THE MYELIN STRUCTURAL PROTEINS AND CONTINUE TO PRODUCE INFLAMMATORY CYTOKINES SUCH AS TUMOR NECROSIS FACTOR ALPHA (TNFALPHA) THAT LEADS TO DIRECT ACTIVATION OF ANTIBODIES AND MACROPHAGES THAT ARE INVOLVED IN THE PHAGOCYTOSIS OF MYELIN. PROLIFERATING OLIGODENDROCYTE PRECURSORS (OPS) MIGRATING TO THE LESION SITES ARE CAPABLE OF ACUTE REMYELINATION BUT UNABLE TO COMPLETELY REPAIR OR RESTORE THE IMMUNE SYSTEM-MEDIATED MYELIN DAMAGE. THIS RESULTS IN VARIOUS PERMANENT CLINICAL NEUROLOGICAL DISABILITIES SUCH AS COGNITIVE DYSFUNCTION, FATIGUE, BOWEL/BLADDER ABNORMALITIES, AND NEUROPATHIC PAIN. AT PRESENT, THERE IS NO CURE FOR MS. RECENT REMYELINATION AND/OR MYELIN REPAIR STRATEGIES HAVE FOCUSED ON THE ROLE OF THE NEUROTROPHIN BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) AND ITS UPSTREAM TRANSCRIPTIONAL REPRESSOR METHYL CPG BINDING PROTEIN (MECP2). RESEARCH IN THE FIELD OF EPIGENETIC THERAPEUTICS INVOLVING HISTONE DEACETYLASE (HDAC) INHIBITORS AND LYSINE ACETYL TRANSFERASE (KAT) INHIBITORS IS BEING EXPLORED TO REPRESS THE DETRIMENTAL EFFECTS OF MECP2. THIS REVIEW WILL ADDRESS THE ROLE OF MECP2 AND BDNF IN REMYELINATION AND/OR MYELIN REPAIR AND THE POTENTIAL OF HDAC AND KAT INHIBITORS AS NOVEL THERAPEUTIC INTERVENTIONS FOR MS. 2016 17 4848 19 OPIOID-INDUCED STRUCTURAL AND FUNCTIONAL PLASTICITY OF MEDIUM-SPINY NEURONS IN THE NUCLEUS ACCUMBENS. OPIOID USE DISORDER (OUD) IS A CHRONIC RELAPSING CLINICAL CONDITION WITH TREMENDOUS MORBIDITY AND MORTALITY THAT FREQUENTLY PERSISTS, DESPITE TREATMENT, DUE TO AN INDIVIDUAL'S UNDERLYING PSYCHOLOGICAL, NEUROBIOLOGICAL, AND GENETIC VULNERABILITIES. EVIDENCE SUGGESTS THAT THESE VULNERABILITIES MAY HAVE NEUROCHEMICAL, CELLULAR, AND MOLECULAR BASES. KEY NEUROPLASTIC EVENTS WITHIN THE MESOCORTICOLIMBIC SYSTEM THAT EMERGE THROUGH CHRONIC EXPOSURE TO OPIOIDS MAY HAVE A DETERMINATIVE INFLUENCE ON BEHAVIORAL SYMPTOMS ASSOCIATED WITH OUD. IN PARTICULAR, STRUCTURAL AND FUNCTIONAL ALTERATIONS IN THE DENDRITIC SPINES OF MEDIUM SPINY NEURONS (MSNS) WITHIN THE NUCLEUS ACCUMBENS (NAC) AND ITS DOPAMINERGIC PROJECTIONS FROM THE VENTRAL TEGMENTAL AREA (VTA) ARE BELIEVED TO FACILITATE THESE BEHAVIORAL SEQUELAE. ADDITIONALLY, GLUTAMATERGIC NEURONS FROM THE PREFRONTAL CORTEX, THE BASOLATERAL AMYGDALA, THE HIPPOCAMPUS, AND THE THALAMUS PROJECT TO THESE SAME MSNS, PROVIDING AN ENRICHED TARGET FOR SYNAPTIC PLASTICITY. HERE, WE REVIEW LITERATURE RELATED TO NEUROADAPTATIONS IN NAC MSNS FROM DOPAMINERGIC AND GLUTAMATERGIC PATHWAYS IN OUD. WE ALSO DESCRIBE NEW FINDINGS RELATED TO TRANSCRIPTIONAL, EPIGENETIC, AND MOLECULAR MECHANISMS IN MSN PLASTICITY IN THE DIFFERENT STAGES OF OUD. 2021 18 687 26 BRAINSTEM BRAIN-DERIVED NEUROTROPHIC FACTOR SIGNALING IS REQUIRED FOR HISTONE DEACETYLASE INHIBITOR-INDUCED PAIN RELIEF. OUR PREVIOUS STUDY DEMONSTRATED THAT PERSISTENT PAIN CAN EPIGENETICALLY SUPPRESS THE TRANSCRIPTION OF GAD2 [ENCODING GLUTAMIC ACID DECARBOXYLASE 65 (GAD65)] AND CONSEQUENTLY IMPAIR THE INHIBITORY FUNCTION OF GABAERGIC SYNAPSES IN CENTRAL PAIN-MODULATING NEURONS. THIS CONTRIBUTES TO THE DEVELOPMENT OF PERSISTENT PAIN SENSITIZATION. HISTONE DEACETYLASE (HDAC) INHIBITORS INCREASED GAD65 ACTIVITY CONSIDERABLY, RESTORED GABA SYNAPTIC FUNCTION, AND RENDERED SENSITIZED PAIN BEHAVIOR LESS PRONOUNCED. HOWEVER, THE MOLECULAR MECHANISMS BY WHICH HDAC REGULATES GABAERGIC TRANSMISSION THROUGH GAD65 UNDER PAIN CONDITIONS ARE UNKNOWN. THIS WORK SHOWED THAT HDAC INHIBITOR-INDUCED INCREASES IN COLOCALIZATION OF GAD65 AND SYNAPTIC PROTEIN SYNAPSIN I ON THE PRESYNAPTIC AXON TERMINALS OF THE NUCLEUS RAPHE MAGNUS (NRM) WERE BLOCKED BY A TRKB RECEPTOR ANTAGONIST K252A [(9S,10R,12R)-2,3,9,10,11,12-HEXAHYDRO-10-HYDROXY-9-METHYL-1-OXO-9,12-EPOXY-1H-DIINDOLO[1,2,3-FG:3',2',1'-KL]PYRROLO[3,4-I][1,6]BENZODIAZOCINE-10-CARBOXYLIC ACID METHYL ESTER], INDICATING THAT BDNF-TRKB SIGNALING MAY BE REQUIRED IN GAD65 MODULATION OF GABA SYNAPTIC FUNCTION. AT THE BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) PROMOTER, HDAC INHIBITORS INDUCED SIGNIFICANT INCREASES IN H3 HYPERACETYLATION, CONSISTENT WITH THE INCREASE IN BDNF MRNA AND TOTAL PROTEINS. ALTHOUGH EXOGENOUS BDNF FACILITATED GABA MINIATURE INHIBITORY POSTSYNAPTIC CURRENTS AND GAD65 ACCUMULATION IN NRM NEURONAL SYNAPSES IN NORMAL RATS, IT FAILED TO DO SO IN ANIMALS SUBJECTED TO PERSISTENT INFLAMMATION. IN ADDITION, BLOCKADE OF THE TRKB RECEPTOR WITH K252A HAS NO EFFECT ON MINIATURE INHIBITORY POSTSYNAPTIC CURRENTS AND SYNAPTIC GAD65 ACCUMULATION UNDER NORMAL CONDITIONS. IN ADDITION, THE ANALGESIC EFFECTS OF HDAC INHIBITORS ON BEHAVIOR WERE BLOCKED BY NRM INFUSION OF K252A. THESE FINDINGS SUGGEST THAT BDNF-TRKB SIGNALING IS REQUIRED FOR DRUGS THAT REVERSE THE EPIGENETIC EFFECTS OF CHRONIC PAIN AT THE GENE LEVEL, SUCH AS HDAC INHIBITORS. 2015 19 5006 29 PERIPHERAL NERVE INJURY IS ACCOMPANIED BY CHRONIC TRANSCRIPTOME-WIDE CHANGES IN THE MOUSE PREFRONTAL CORTEX. BACKGROUND: PERIPHERAL NERVE INJURY CAN HAVE LONG-TERM CONSEQUENCES INCLUDING PAIN-RELATED MANIFESTATIONS, SUCH AS HYPERSENSITIVITY TO CUTANEOUS STIMULI, AS WELL AS AFFECTIVE AND COGNITIVE DISTURBANCES, SUGGESTING THE INVOLVEMENT OF SUPRASPINAL MECHANISMS. CHANGES IN BRAIN STRUCTURE AND CORTICAL FUNCTION ASSOCIATED WITH MANY CHRONIC PAIN CONDITIONS HAVE BEEN REPORTED IN THE PREFRONTAL CORTEX (PFC). THE PFC IS IMPLICATED IN PAIN-RELATED CO-MORBIDITIES SUCH AS DEPRESSION, ANXIETY AND IMPAIRED EMOTIONAL DECISION-MAKING ABILITY. WE RECENTLY REPORTED THAT THIS REGION IS SUBJECT TO SIGNIFICANT EPIGENETIC REPROGRAMMING FOLLOWING PERIPHERAL NERVE INJURY, AND NORMALIZATION OF PAIN-RELATED STRUCTURAL, FUNCTIONAL AND EPIGENETIC ABNORMALITIES IN THE PFC ARE ALL ASSOCIATED WITH EFFECTIVE PAIN REDUCTION. IN THIS STUDY, WE USED THE SPARED NERVE INJURY (SNI) MODEL OF NEUROPATHIC PAIN TO TEST THE HYPOTHESIS THAT PERIPHERAL NERVE INJURY TRIGGERS PERSISTENT LONG-LASTING CHANGES IN GENE EXPRESSION IN THE PFC, WHICH ALTER FUNCTIONAL GENE NETWORKS, THUS PROVIDING A POSSIBLE EXPLANATION FOR CHRONIC PAIN ASSOCIATED BEHAVIORS. RESULTS: SNI OR SHAM SURGERY WHERE PERFORMED IN MALE CD1 MICE AT THREE MONTHS OF AGE. SIX MONTHS AFTER INJURY, WE PERFORMED TRANSCRIPTOME-WIDE SEQUENCING (RNASEQ), WHICH REVEALED 1147 DIFFERENTIALLY REGULATED TRANSCRIPTS IN THE PFC IN NERVE-INJURED VS. CONTROL MICE. CHANGES IN GENE EXPRESSION OCCURRED ACROSS A NUMBER OF FUNCTIONAL GENE CLUSTERS ENCODING CARDINAL BIOLOGICAL PROCESSES AS REVEALED BY INGENUITY PATHWAY ANALYSIS. SIGNIFICANTLY ALTERED BIOLOGICAL PROCESSES INCLUDED NEUROLOGICAL DISEASE, SKELETAL MUSCULAR DISORDERS, BEHAVIOR, AND PSYCHOLOGICAL DISORDERS. SEVERAL OF THE CHANGES DETECTED BY RNASEQ WERE VALIDATED BY RT-QPCR AND INCLUDED TRANSCRIPTS WITH KNOWN ROLES IN CHRONIC PAIN AND/OR NEURONAL PLASTICITY INCLUDING THE NMDA RECEPTOR (GLUTAMATE RECEPTOR, IONOTROPIC, NMDA; GRIN1), NEURITE OUTGROWTH (ROUNDABOUT 3; ROBO3), GLIOSIS (GLIAL FIBRILLARY ACIDIC PROTEIN; GFAP), VESICULAR RELEASE (SYNAPTOTAGMIN 2; SYT2), AND NEURONAL EXCITABILITY (VOLTAGE-GATED SODIUM CHANNEL, TYPE I; SCN1A). CONCLUSIONS: THIS STUDY USED AN UNBIASED APPROACH TO DOCUMENT LONG-TERM ALTERATIONS IN GENE EXPRESSION IN THE BRAIN FOLLOWING PERIPHERAL NERVE INJURY. WE PROPOSE THAT THESE CHANGES ARE MAINTAINED AS A MEMORY OF AN INSULT THAT IS TEMPORALLY AND SPATIALLY DISTANT FROM THE INITIAL INJURY. 2013 20 881 21 CHRONIC CLOZAPINE TREATMENT RESTRAINS VIA HDAC2 THE PERFORMANCE OF MGLU2 RECEPTOR AGONISM IN A RODENT MODEL OF ANTIPSYCHOTIC ACTIVITY. PRECLINICAL FINDINGS IN RODENT MODELS POINTED TOWARD ACTIVATION OF METABOTROPIC GLUTAMATE 2/3 (MGLU2/3) RECEPTORS AS A NEW PHARMACOLOGICAL APPROACH TO TREAT PSYCHOSIS. HOWEVER, MORE RECENT STUDIES FAILED TO SHOW CLINICAL EFFICACY OF MGLU2/3 RECEPTOR AGONISM IN SCHIZOPHRENIA PATIENTS. WE PREVIOUSLY PROPOSED THAT LONG-TERM ANTIPSYCHOTIC MEDICATION RESTRICTED THE THERAPEUTIC EFFECTS OF THESE GLUTAMATERGIC AGENTS. HOWEVER, LITTLE IS KNOWN ABOUT THE MOLECULAR MECHANISM UNDERLYING THE POTENTIAL REPERCUSSION OF PREVIOUS ANTIPSYCHOTIC EXPOSURE ON THE THERAPEUTIC PERFORMANCE OF MGLU2/3 RECEPTOR AGONISTS. HERE WE SHOW THAT THIS MALADAPTIVE EFFECT OF ANTIPSYCHOTIC TREATMENT IS MEDIATED MOSTLY VIA HISTONE DEACETYLASE 2 (HDAC2). CHRONIC TREATMENT WITH THE ANTIPSYCHOTIC CLOZAPINE LED TO A DECREASE IN MOUSE FRONTAL CORTEX MGLU2 MRNA, AN EFFECT THAT REQUIRED EXPRESSION OF BOTH HDAC2 AND THE SEROTONIN 5-HT(2A) RECEPTOR. THIS TRANSCRIPTIONAL ALTERATION OCCURRED IN ASSOCIATION WITH HDAC2-DEPENDENT REPRESSIVE HISTONE MODIFICATIONS AT THE MGLU2 PROMOTER. WE FOUND THAT CHRONIC CLOZAPINE TREATMENT DECREASED VIA HDAC2 THE CAPABILITIES OF THE MGLU2/3 RECEPTOR AGONIST LY379268 TO ACTIVATE G-PROTEINS IN THE FRONTAL CORTEX OF MICE. CHRONIC CLOZAPINE TREATMENT BLUNTED THE ANTIPSYCHOTIC-RELATED BEHAVIORAL EFFECTS OF LY379268, AN EFFECT THAT WAS NOT OBSERVED IN HDAC2 KNOCKOUT MICE. MORE IMPORTANTLY, CO-ADMINISTRATION OF THE CLASS I AND II HDAC INHIBITOR SAHA (VORINOSTAT) PRESERVED THE ANTIPSYCHOTIC PROFILE OF LY379268 AND FRONTAL CORTEX MGLU2/3 RECEPTOR DENSITY IN WILD-TYPE MICE. THESE FINDINGS RAISE CONCERNS ON THE DESIGN OF PREVIOUS CLINICAL STUDIES WITH MGLU2/3 AGONISTS, PROVIDING THE RATIONALE FOR THE DEVELOPMENT OF HDAC2 INHIBITORS AS A NEW EPIGENETIC-BASED APPROACH TO IMPROVE THE CURRENTLY LIMITED RESPONSE TO TREATMENT WITH GLUTAMATERGIC ANTIPSYCHOTICS. 2019