{"gene":"NPAS2","run_date":"2026-04-29T11:37:57","timeline":{"discoveries":[{"year":2001,"finding":"NPAS2 forms an obligate heterodimer with BMAL1, and the DNA-binding activity of the NPAS2:BMAL1 heterodimer is strongly enhanced by reduced NAD cofactors (NADH and NADPH) and inhibited by their oxidized forms in a purified (cell-free) system.","method":"In vitro DNA-binding assay with purified proteins and NAD cofactors","journal":"Science","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro with purified proteins, replicated across CLOCK:BMAL1 and NPAS2:BMAL1 heterodimers","pmids":["11441146"],"is_preprint":false},{"year":2001,"finding":"NPAS2:BMAL1 heterodimer functions as a transcriptional activator of Per1, Per2, and Cry1 genes (via E-box elements) and represses BMAL1, establishing NPAS2 as a component of the circadian transcriptional feedback loop operative in the mammalian forebrain. Per2 mRNA oscillation in frontal cortex is abolished in NPAS2-deficient mice.","method":"Conditional induction system in neuroblastoma cells, DNA microarrays, Northern blotting, in situ hybridization in NPAS2-knockout mice","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods in cell lines and knockout mice, replicated in vivo","pmids":["11441147"],"is_preprint":false},{"year":2002,"finding":"Both PAS-A and PAS-B domains of NPAS2 bind heme as a prosthetic group; heme-loaded (holo) NPAS2:BMAL1 heterodimers bind DNA avidly under reducing conditions, but low micromolar CO inhibits DNA binding of holo-NPAS2 and promotes formation of inactive BMAL1 homodimers at the expense of NPAS2:BMAL1 heterodimers.","method":"In vitro DNA-binding assay, spectroscopy, heme-binding biochemistry with apo and holo NPAS2 proteins","journal":"Science","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro with defined apo/holo states and gas treatment, multiple orthogonal methods","pmids":["12446832"],"is_preprint":false},{"year":2000,"finding":"NPAS2 is a bHLH-PAS transcription factor whose expression is spatiotemporally coincident with formation of the frontal association/limbic forebrain pathway; NPAS2-deficient mice exhibit deficits in long-term memory in cued and contextual fear tasks, indicating a dedicated regulatory role in memory acquisition.","method":"Targeted lacZ knock-in, behavioral testing (cued and contextual fear conditioning) in knockout mice","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 — clean KO with specific behavioral phenotype, well-controlled study","pmids":["10864874"],"is_preprint":false},{"year":2003,"finding":"NPAS2 plays a substantive role in maintaining circadian locomotor behaviors under normal light-dark and feeding conditions and is critical for food-entrainment adaptability, as shown by disrupted behavioral rhythms and impaired adaptation to restricted feeding schedules in NPAS2-deficient mice.","method":"Locomotor activity monitoring, sleep EEG, restricted food-driven entrainment assays in NPAS2-knockout mice","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 — clean KO with multiple defined behavioral phenotypes, replicated across conditions","pmids":["12843397"],"is_preprint":false},{"year":2001,"finding":"Nuclear receptors RARα and RXRα interact with NPAS2 (MOP4) and negatively regulate CLOCK/MOP4:BMAL1-mediated transcriptional activation of clock gene expression in vascular cells; retinoic acid can phase-shift Per2 mRNA rhythmicity in vivo.","method":"Co-immunoprecipitation, reporter gene assays, in vivo retinoic acid treatment","journal":"Cell","confidence":"Medium","confidence_rationale":"Tier 2 — reciprocal interaction shown and functional consequence measured, single lab","pmids":["11439184"],"is_preprint":false},{"year":2006,"finding":"CRY proteins stabilize unphosphorylated forms of CLOCK(NPAS2) and BMAL1 and cause their nuclear accumulation, inhibiting transcriptional activity without disrupting complex formation or DNA binding; this posttranslational regulation is CRY-specific and is confirmed in Cry double-knockout mice.","method":"Ectopic co-expression, immunofluorescence, Western blot of phosphorylation states, reporter assays, Cry double-KO mouse tissues","journal":"Cell cycle","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods in cells and confirmed in vivo, single lab","pmids":["16628007"],"is_preprint":false},{"year":2006,"finding":"NPAS2 acts as a transcriptional regulator of non-rapid eye movement sleep homeostasis in a sex-dependent manner; in npas2-/- mice, sleep spindle EEG activity is reduced, delta frequency shifts, and the wake-dependent increase in cortical Per2 expression after sleep deprivation is attenuated, implying NPAS2 drives Per2 transcription in cortex in response to sleep pressure.","method":"EEG/EMG recording, sleep deprivation protocol, cortical Per2 mRNA measurement in npas2-/- mice","journal":"PNAS","confidence":"High","confidence_rationale":"Tier 2 — clean KO with multiple EEG and molecular phenotypes, replicated across sex conditions","pmids":["16636276"],"is_preprint":false},{"year":2006,"finding":"The heme-bound bHLH-PAS-A domain of NPAS2 exists predominantly as a dimer; the bHLH domain assists stable heme binding (rate constant >100-fold higher than isolated PAS-A alone) and is required for E-box DNA binding in the presence of heme, as shown by quartz-crystal microbalance and spectroscopic analysis.","method":"Optical absorption and resonance Raman spectroscopy, heme-binding kinetics, quartz-crystal microbalance DNA-binding assay","journal":"FEBS Journal","confidence":"High","confidence_rationale":"Tier 1 — multiple in vitro biophysical and biochemical methods with domain-deletion analysis","pmids":["16704425"],"is_preprint":false},{"year":2008,"finding":"Mutation of the heme axial ligands His119 or His171 in the NPAS2 PAS-A domain impairs heterodimer formation with BMAL1 and abolishes DNA binding to the E-box, demonstrating that heme coordination is required for NPAS2 transcriptional activity.","method":"Site-directed mutagenesis of full-length NPAS2, reporter gene (Per1 promoter) assay in NIH3T3 cells, gel-shift assay with isolated bHLH-PAS-A domain","journal":"Biochemical and Biophysical Research Communications","confidence":"High","confidence_rationale":"Tier 1 — active-site mutagenesis combined with DNA-binding and transcriptional assays","pmids":["18230344"],"is_preprint":false},{"year":2011,"finding":"Interaction of the PAS-A domain with the bHLH domain of NPAS2 shifts heme axial coordination from a Cys170/His119 equilibrium (isolated PAS-A) to a His119/His171 (bis-His) coordination; His119 and His171 are the functional axial ligands in the bHLH-PAS-A context.","method":"Resonance Raman spectroscopy of His and Cys mutants of bHLH-PAS-A domain","journal":"Journal of Inorganic Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — systematic mutagenesis + resonance Raman spectroscopy establishing coordination structure","pmids":["22245004"],"is_preprint":false},{"year":2008,"finding":"NPAS2 and CLOCK have overlapping, redundant roles in circadian transcription of Factor VII in the liver; FVII mRNA rhythms are abolished only in Clock-/-;Npas2-/- double-knockout mice but are robust in each single knockout, and both NPAS2:BMAL1 and CLOCK:BMAL1 activate FVII transcription ~4-fold via E-box elements, with this activation suppressed by PER2 and CRY1.","method":"Double-knockout mouse genetics, reporter gene assays, E-box mutagenesis, plasma FVII measurement","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 1-2 — genetic epistasis with reporter assays and mutagenesis, in vivo and in vitro","pmids":["18316400"],"is_preprint":false},{"year":2010,"finding":"NPAS2 is a direct transcriptional target of RORα and REV-ERBα; both nuclear receptors occupy the NPAS2 promoter at two functional ROR-response elements (ROREs) identified by ChIP/microarray, and both regulate NPAS2 mRNA expression, coordinating the positive arm of the circadian feedback loop.","method":"ChIP/microarray (ChIP-on-chip), luciferase reporter assays with RORE mutants, RT-PCR","journal":"Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — ChIP-on-chip plus functional reporter mutagenesis, two nuclear receptors validated","pmids":["20817722"],"is_preprint":false},{"year":2011,"finding":"NPAS2 and BMAL1 bind to E-box sequences of Per2, Cry1, Dbp, and Per1 in the mouse cerebral cortex in a time-of-day-dependent manner (peak ~ZT6); sleep deprivation decreases NPAS2:BMAL1 binding to Per2 despite increasing Per2 mRNA, and decreases CLOCK:BMAL1 binding to Dbp consistent with reduced Dbp mRNA.","method":"Chromatin immunoprecipitation (ChIP) at multiple zeitgeber times in cerebral cortex, qPCR","journal":"PLoS ONE","confidence":"Medium","confidence_rationale":"Tier 2 — direct ChIP in vivo at multiple time points and after sleep deprivation, single lab","pmids":["22039518"],"is_preprint":false},{"year":2016,"finding":"NPAS2 can compensate for loss of CLOCK in peripheral circadian oscillators (fibroblasts) as well as SCN neurons; knockdown of Npas2 in CLOCK-deficient fibroblasts causes arrhythmicity, demonstrating that NPAS2 sustains autonomous circadian rhythms in peripheral cells.","method":"Single-cell bioluminescence imaging of PER2::LUC in CLOCK-deficient fibroblasts with Npas2 siRNA knockdown, luminometry","journal":"PLoS Genetics","confidence":"High","confidence_rationale":"Tier 2 — genetic complementation and siRNA knockdown with real-time imaging, clear molecular phenotype","pmids":["26895328"],"is_preprint":false},{"year":2013,"finding":"NAD(P)H enhances NPAS2:BMAL1 DNA binding specifically; the N-terminal 1–61 residues of NPAS2 (within the bHLH domain) are sufficient to sense NAD(P)H and mediate this enhancement; NAD(P)+ does not inhibit NPAS2 binding under these assay conditions.","method":"Electrophoretic mobility shift assay (EMSA) with truncation mutants of NPAS2 bHLH domain and various NAD derivatives","journal":"Biochemical and Biophysical Research Communications","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro assay with systematic truncation mutants, single lab","pmids":["23831463"],"is_preprint":false},{"year":2013,"finding":"Cell-autonomous circadian transcription of the Npas2 gene requires a specific RORE in its upstream promoter and endogenous RORα; dominant-negative RORα, RORα siRNA, and RORα-mutant (sg/sg) mouse embryonic fibroblasts all display damped Npas2 transcriptional oscillations.","method":"RORE promoter mutagenesis, dominant-negative and siRNA constructs, RORα-mutant mouse fibroblasts, luciferase reporter","journal":"Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — promoter mutagenesis, multiple genetic tools, and in vivo confirmation in mutant mice","pmids":["24196956"],"is_preprint":false},{"year":2008,"finding":"RNA interference-mediated knockdown of NPAS2 in human cells impairs cell cycle delay in response to mutagen treatment and reduces DNA repair capacity (comet assay); a PCR expression array shows that NPAS2 knockdown represses several cell cycle and DNA repair genes.","method":"RNAi knockdown, comet assay, cell cycle analysis, pathway-based PCR expression array","journal":"Molecular Cancer Research","confidence":"Medium","confidence_rationale":"Tier 2 — multiple assays in KD cells, single lab, functional consequence defined","pmids":["18819933"],"is_preprint":false},{"year":2009,"finding":"Genome-wide ChIP-on-chip identified 26 genomic loci bound by NPAS2 in MCF-7 cells; 16 were confirmed by qPCR, including cancer-related targets ARHGAP29, CDC25A, CDKN2AIP, CX3CL1, ELF4, GNAL, KDELR1, POU4F2, and THRA.","method":"ChIP-on-chip (genome-wide), confirmatory real-time PCR","journal":"Cancer Letters","confidence":"Medium","confidence_rationale":"Tier 2 — genome-wide ChIP with PCR validation, single lab","pmids":["19457610"],"is_preprint":false},{"year":2014,"finding":"NPAS2 directly transcriptionally activates the Drd3 dopamine receptor gene in the nucleus accumbens (NAc); NPAS2 expression is restricted to Drd1+ neurons in NAc; NPAS2 knockdown in NAc reduces cocaine conditioned place preference and disrupts the diurnal rhythm of Drd3 expression.","method":"AAV-shRNA knockdown in NAc, ChIP-seq, conditioned place preference, cell sorting qRT-PCR","journal":"Biological Psychiatry","confidence":"High","confidence_rationale":"Tier 2 — ChIP-seq identifies direct binding, viral knockdown with behavioral and molecular phenotypes, orthogonal methods","pmids":["25444159"],"is_preprint":false},{"year":2010,"finding":"Both CLOCK and NPAS2 bind the Aanat promoter E-box in chicken photoreceptors (ChIP); NPAS2 knockdown damps the circadian rhythm of Aanat mRNA, while CLOCK knockdown reduces Npas2 expression, demonstrating overlapping roles with CLOCK as the dominant regulator of the photoreceptor clockwork.","method":"Gene-specific miRNA knockdown vectors in photoreceptor cell cultures, ChIP, circadian mRNA measurements","journal":"Journal of Neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP shows direct binding, knockdown shows functional redundancy, avian model","pmids":["20345751"],"is_preprint":false},{"year":2017,"finding":"NPAS2 heterodimerizes with BMAL1 to bind the E-box element in the CDC25A promoter and transcriptionally upregulates CDC25A phosphatase, which drives CDK2/4/6 dephosphorylation (promoting cell proliferation) and Bcl-2 upregulation (inhibiting apoptosis) in hepatocellular carcinoma cells.","method":"Co-immunoprecipitation, ChIP, luciferase reporter assay, overexpression/knockdown with cell cycle and apoptosis readouts, xenograft in vivo","journal":"Cell Death & Disease","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP and Co-IP with functional rescue experiments, single lab","pmids":["28333141"],"is_preprint":false},{"year":2017,"finding":"NPAS2 regulates anxiety-like behavior through transcriptional control of Gabra (GABA-A receptor subunit) genes in the ventral striatum; Npas2 null mutant mice show reduced anxiety and decreased sensitivity to diazepam, and NAc-specific Npas2 knockdown reduces Gabra1 expression.","method":"Global Npas2 null mutant behavioral testing (elevated plus maze, light/dark box, open field), AAV-shRNA striatal knockdown, acute/chronic stress Npas2 expression measurement","journal":"Frontiers in Molecular Neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 — KO and region-specific knockdown with behavioral and molecular phenotypes, single lab","pmids":["29163035"],"is_preprint":false},{"year":2019,"finding":"NPAS2 directly transcriptionally activates HIF-1α, which mediates upregulation of glycolytic genes (GLUT1, HK2, GPI, ALDOA, ENO2, PKM2, MCT4) and downregulation of PGC-1α/mitochondrial biogenesis in hepatocellular carcinoma cells, promoting the Warburg effect.","method":"Overexpression/knockdown of NPAS2, luciferase reporter assays, ChIP, in vitro and xenograft in vivo metabolic assays","journal":"Cancer Letters","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP with reporter assays and functional metabolic rescue, single lab","pmids":["31765736"],"is_preprint":false},{"year":2019,"finding":"NPAS2 directly transcriptionally activates Hes1 (a Notch signaling target) in hepatic stellate cells, promoting liver fibrogenesis; NPAS2 is upregulated in hepatic stellate cells after fibrogenic injury.","method":"Luciferase reporter assay, ChIP, NPAS2 overexpression/knockdown in hepatic stellate cells, in vivo fibrosis model","journal":"Molecular Therapy: Nucleic Acids","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP and reporter assays with in vivo fibrosis confirmation, single lab","pmids":["31778954"],"is_preprint":false},{"year":2019,"finding":"NPAS2 regulates excitatory synaptic transmission specifically in D1R-expressing medium spiny neurons (MSNs) of the nucleus accumbens; cell-type-specific Npas2 knockdown in D1R-MSNs (but not D2R-MSNs) increases excitatory drive, blocks cocaine-induced synaptic potentiation, and reduces cocaine conditioned place preference.","method":"Viral-mediated cell-type-specific Npas2 knockdown with Cre-inducible shRNA, electrophysiology (mEPSC), conditioned place preference in Drd1a-tdTomato mice","journal":"Journal of Neuroscience","confidence":"High","confidence_rationale":"Tier 2 — cell-type-specific genetic manipulation with electrophysiology and behavior, orthogonal methods","pmids":["30962277"],"is_preprint":false},{"year":2021,"finding":"NPAS2 interacts with CRY2 by co-immunoprecipitation and directly activates the CX3CL1 promoter; overexpression of NPAS2 upregulates CX3CL1, which activates the downstream AKT/mTOR pathway to inhibit autophagy and protect against cardiomyocyte apoptosis from hypoxia/reoxygenation injury.","method":"Co-immunoprecipitation, luciferase reporter assay (CX3CL1 promoter), overexpression in cardiomyocytes, in vivo rat I/R model","journal":"Aging","confidence":"Medium","confidence_rationale":"Tier 3 — single Co-IP plus reporter assay, in vivo confirmation, single lab","pmids":["34460437"],"is_preprint":false},{"year":2017,"finding":"ARNTL2/NPAS2 forms a heterodimeric complex that induces PER3 and DBP expression, but is a weaker inducer than the canonical ARNTL/NPAS2 dimer; DEC2 blocks ARNTL2/NPAS2-driven expression; TNF promotes nuclear localization of ARNTL2 and induces ARNTL2 and NPAS2 via NF-κB signaling.","method":"Transfection of cloned constructs in HEK293, RT-qPCR, immunofluorescence staining, NF-κB pathway inhibitor (IKK-2 inhibitor IMD-0354)","journal":"Journal of Circadian Rhythms","confidence":"Medium","confidence_rationale":"Tier 3 — transfection/reporter approach with pharmacological inhibition, single lab","pmids":["30210560"],"is_preprint":false},{"year":2022,"finding":"NPAS2 and SIRT1 physically interact (co-immunoprecipitation) in the mouse nucleus accumbens; both show diurnal expression regulated by NAD+; they share transcriptional targets enriched in reward and metabolic pathways (cross-ChIP-seq analysis); NAc-specific Npas2 knockdown or functional Npas2 mutation attenuates SIRT1-mediated increases in cocaine preference.","method":"Co-immunoprecipitation, diurnal NAD+ measurement, ChIP-seq cross-analysis, AAV-shRNA NAc knockdown, cocaine conditioned place preference","journal":"European Journal of Neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus ChIP-seq plus behavioral rescue, single lab","pmids":["35001440"],"is_preprint":false},{"year":2022,"finding":"NPAS2 transcriptionally activates hepatic CYP1A2 by binding to an E-box-like element at −416 bp in the Cyp1a2 promoter; Npas2 knockout mice show decreased CYP1A2 mRNA, protein, and enzymatic activity with loss of diurnal rhythmicity.","method":"Npas2-/- knockout mice, luciferase reporter assay, ChIP-seq, in vivo pharmacokinetic (theophylline/phenacetin) assays","journal":"Biochemical Pharmacology","confidence":"High","confidence_rationale":"Tier 1-2 — ChIP-seq with reporter mutagenesis and in vivo enzymatic confirmation in KO mice","pmids":["36379250"],"is_preprint":false},{"year":2023,"finding":"p53 transcriptionally activates NPAS2 in alveolar type II epithelial cells; NPAS2 in turn promotes epithelial-mesenchymal transition (EMT) by transcriptionally upregulating HES1, and NPAS2 overexpression partially rescues the anti-EMT effects of TP53 knockdown.","method":"Bleomycin-induced fibrosis mouse model, siRNA knockdown, overexpression, luciferase reporter assay, in vitro EMT assays","journal":"Cellular Signalling","confidence":"Medium","confidence_rationale":"Tier 2 — reporter assay showing p53→NPAS2→HES1 axis, functional rescue experiments, single lab","pmids":["37406788"],"is_preprint":false},{"year":2025,"finding":"In macrophages, FTO (m6A demethylase) reduces m6A modification on Npas2 mRNA through a PRRC2A-dependent mechanism, decreasing Npas2 stability; loss of this suppression leads to elevated NPAS2, which activates HIF-1α signaling to promote glycolysis and M1 macrophage activation in diabetic nephropathy.","method":"MeRIP-seq, transcriptome analysis, loss/gain-of-function of FTO and NPAS2 in bone marrow-derived macrophages, db/db mouse model","journal":"FASEB Journal","confidence":"Medium","confidence_rationale":"Tier 2 — MeRIP-seq identifies m6A site, functional epistasis in cells and in vivo, single lab","pmids":["39831513"],"is_preprint":false},{"year":2026,"finding":"mPFC-expressed NPAS2 orchestrates afternoon nap behavior by circadian suppression of dopamine synthesis: NPAS2 transcriptionally activates the repressor POU2F2, which downregulates tyrosine hydroxylase (TH) expression and dopamine production in TH+ mPFC neurons, reducing their wake-promoting activity during nap hours.","method":"In vivo sleep/nap monitoring, ChIP, luciferase reporter assay, viral-mediated region-specific NPAS2 manipulation, TH+ neuron electrophysiology in mice","journal":"Nature Communications","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP and reporter assays defining NPAS2→POU2F2→TH pathway, region-specific manipulation with behavioral and neuronal activity readouts, single lab","pmids":["41839866"],"is_preprint":false},{"year":2025,"finding":"NPAS2 transcriptionally represses LPCAT3 expression in vascular smooth muscle cells (VSMCs); loss of NPAS2 elevates LPCAT3 and accumulation of phosphatidylcholines with two polyunsaturated fatty acyl chains (PC-PUFA2S), promoting ferroptosis-induced VSMC phenotypic switching and ascending thoracic aortic aneurysm progression.","method":"VSMC-specific Npas2 knockout mice, PDGF-BB treatment, ChIP/reporter assays, lipidomic analysis, ATAA mouse model","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 — preprint, single lab, mechanistic model based on ChIP and KO phenotype","pmids":[],"is_preprint":true}],"current_model":"NPAS2 is a heme-binding, NAD(P)H-responsive, CO-sensitive bHLH-PAS transcription factor that forms obligate heterodimers with BMAL1 to activate circadian target genes (Per1, Per2, Cry1, Drd3, CYP1A2, CDC25A, HES1, CX3CL1, and others) via E-box elements; its transcriptional activity is regulated at multiple levels including redox state (NAD(P)H), gas sensing (CO via heme in PAS-A/B domains), CRY-mediated posttranslational stabilization, and RORα/REV-ERBα-dependent transcription of the Npas2 gene itself, while functionally it serves as the predominant circadian transcription factor in forebrain structures (especially nucleus accumbens) where it controls sleep homeostasis, memory, reward sensitivity, and anxiety by regulating dopamine receptor expression, GABAergic signaling, and synaptic plasticity in a cell-type- and sex-specific manner."},"narrative":{"teleology":[{"year":2000,"claim":"NPAS2 was established as a forebrain-enriched bHLH-PAS transcription factor required for long-term memory, revealing that this PAS-domain protein had dedicated neurological functions beyond a predicted role as a generic transcription factor.","evidence":"Targeted lacZ knock-in and behavioral testing (cued and contextual fear conditioning) in Npas2 knockout mice","pmids":["10864874"],"confidence":"High","gaps":["Transcriptional targets mediating the memory phenotype were unknown","Whether NPAS2 functioned as a circadian factor in the brain was not addressed"]},{"year":2001,"claim":"NPAS2 was shown to heterodimerize with BMAL1 and function as a circadian transcription factor activating Per1, Per2, and Cry1 via E-box elements, with DNA-binding activity modulated by NAD(P)H redox state, linking metabolic sensing to the clock mechanism.","evidence":"In vitro DNA-binding assays with purified proteins and NAD cofactors; conditional induction system in neuroblastoma cells, microarrays, and Northern blotting; Per2 oscillation abolished in Npas2-KO forebrain","pmids":["11441146","11441147"],"confidence":"High","gaps":["Whether NAD(P)H acted directly on NPAS2 or through an intermediary was unclear","The heme-binding properties of NPAS2 had not been characterized"]},{"year":2001,"claim":"Retinoic acid receptors RARα and RXRα were found to interact with NPAS2 and negatively regulate NPAS2:BMAL1-driven transcription, identifying a non-core-clock input pathway to circadian gene regulation in vascular cells.","evidence":"Co-immunoprecipitation, reporter gene assays, in vivo retinoic acid treatment shifting Per2 rhythms","pmids":["11439184"],"confidence":"Medium","gaps":["Whether RARα/RXRα regulation of NPAS2 occurs in vivo under physiological retinoid levels was not established","The structural basis of the interaction was not defined"]},{"year":2002,"claim":"Both PAS-A and PAS-B domains of NPAS2 were shown to bind heme, and carbon monoxide was identified as a gaseous signal that inhibits NPAS2:BMAL1 DNA binding and promotes inactive BMAL1 homodimers, establishing NPAS2 as a heme-based gas sensor.","evidence":"In vitro DNA-binding assays with apo/holo NPAS2 proteins, spectroscopy, and CO gas treatment","pmids":["12446832"],"confidence":"High","gaps":["The axial ligand identity for heme coordination was not resolved","Whether CO regulation occurs at physiological intracellular concentrations in vivo was unknown"]},{"year":2003,"claim":"NPAS2 was established as functionally important for circadian locomotor behavior and food-entrainable rhythms in vivo, extending its role from a forebrain transcription factor to a bona fide circadian clock component regulating whole-organism behavioral outputs.","evidence":"Locomotor activity monitoring, sleep EEG, and restricted-feeding entrainment assays in Npas2-KO mice","pmids":["12843397"],"confidence":"High","gaps":["The degree of redundancy between NPAS2 and CLOCK in different tissues was not quantified","Whether NPAS2 was required in the SCN or only in extra-SCN oscillators was unresolved"]},{"year":2006,"claim":"Three advances refined the molecular mechanism: CRY proteins were shown to stabilize unphosphorylated NPAS2 and BMAL1 to repress transcription posttranslationally; NPAS2 was found to regulate NREM sleep homeostasis and cortical Per2 induction in a sex-dependent manner; and the bHLH domain was shown to be required for stable heme binding and E-box DNA recognition.","evidence":"Co-expression, phosphorylation analysis, and reporter assays in cells and Cry-DKO mice; EEG/EMG recording with sleep deprivation in Npas2-KO mice; resonance Raman spectroscopy and QCM DNA-binding assays with domain truncations","pmids":["16628007","16636276","16704425"],"confidence":"High","gaps":["How CRY inhibits transcription while preserving DNA binding was mechanistically unclear","The identity of the functional heme axial ligands was still debated"]},{"year":2008,"claim":"Site-directed mutagenesis of His119 and His171 in PAS-A proved these are the essential heme axial ligands required for BMAL1 heterodimerization and E-box DNA binding, while genetic studies demonstrated NPAS2 and CLOCK are functionally redundant in peripheral circadian transcription.","evidence":"Mutagenesis with Per1-reporter and gel-shift assays in NIH3T3; Clock/Npas2 double-KO mice with FVII rhythmic transcription analysis","pmids":["18230344","18316400"],"confidence":"High","gaps":["Whether heme occupancy in vivo is limiting or constitutive was unknown","The structural basis for NPAS2 vs. CLOCK interchangeability was not defined"]},{"year":2008,"claim":"NPAS2 knockdown in human cells impaired DNA damage-induced cell cycle arrest and repair capacity, suggesting a role for NPAS2 in genotoxic stress responses beyond circadian timekeeping.","evidence":"RNAi knockdown, comet assay, cell cycle analysis, and PCR expression array in human cells","pmids":["18819933"],"confidence":"Medium","gaps":["Direct transcriptional targets mediating DNA repair were not identified by ChIP","Whether this function requires BMAL1 heterodimerization was not tested"]},{"year":2010,"claim":"Npas2 itself was identified as a direct transcriptional target of RORα and REV-ERBα via functional ROR-response elements in its promoter, closing a regulatory loop between the auxiliary and core circadian feedback circuits.","evidence":"ChIP-on-chip, luciferase reporter assays with RORE mutants, RT-PCR; confirmed by RORE mutagenesis and RORα-mutant (sg/sg) fibroblasts","pmids":["20817722","24196956"],"confidence":"High","gaps":["Whether RORα- and REV-ERBα-mediated regulation of Npas2 is tissue-specific was not fully addressed"]},{"year":2011,"claim":"Resonance Raman spectroscopy with systematic mutants resolved the heme coordination mechanism: interdomain interaction between bHLH and PAS-A switches axial ligation from a Cys170/His119 equilibrium to bis-His (His119/His171) coordination, finalizing the structural basis for gas sensing.","evidence":"Resonance Raman spectroscopy of His and Cys mutants of the bHLH-PAS-A domain","pmids":["22245004"],"confidence":"High","gaps":["No crystal structure of the heme-bound bHLH-PAS-A domain exists","How CO binding induces the conformational change that disrupts BMAL1 interaction remains structurally unresolved"]},{"year":2011,"claim":"ChIP in mouse cerebral cortex demonstrated time-of-day-dependent NPAS2:BMAL1 occupancy at Per2, Cry1, Dbp, and Per1 E-boxes in vivo, with sleep deprivation paradoxically decreasing NPAS2 binding at Per2 despite increasing Per2 mRNA, revealing a dissociation between occupancy and transcript output under sleep pressure.","evidence":"Chromatin immunoprecipitation at multiple zeitgeber times in cerebral cortex with and without sleep deprivation","pmids":["22039518"],"confidence":"Medium","gaps":["The mechanism by which Per2 mRNA increases while NPAS2 binding decreases was not explained","Cell-type resolution of cortical ChIP was lacking"]},{"year":2013,"claim":"The NAD(P)H-sensing domain was mapped to residues 1–61 within the bHLH domain, demonstrating that redox sensing and heme-based gas sensing operate through distinct structural elements of NPAS2.","evidence":"EMSA with systematic truncation mutants of the NPAS2 bHLH domain","pmids":["23831463"],"confidence":"Medium","gaps":["The molecular identity of the NAD(P)H-binding site within residues 1–61 was not determined","Whether this redox sensing operates independently of heme in vivo was not tested"]},{"year":2014,"claim":"NPAS2 was shown to be selectively expressed in D1R-positive medium spiny neurons of the nucleus accumbens, where it directly activates Drd3 transcription and regulates cocaine reward; this established NPAS2 as a cell-type-specific circadian regulator of dopaminergic signaling in the reward circuit.","evidence":"AAV-shRNA knockdown in NAc, ChIP-seq identifying Drd3 as direct target, cell sorting qRT-PCR, conditioned place preference","pmids":["25444159"],"confidence":"High","gaps":["Whether NPAS2 regulation of Drd3 involves BMAL1 co-binding at the Drd3 E-box was not shown","The full NPAS2 targetome in D1R-MSNs was not defined"]},{"year":2016,"claim":"NPAS2 was demonstrated to sustain autonomous circadian rhythms in peripheral cells (fibroblasts) in the absence of CLOCK, resolving the longstanding question of whether NPAS2's redundancy with CLOCK extends beyond the forebrain to peripheral oscillators.","evidence":"Single-cell PER2::LUC bioluminescence imaging in CLOCK-deficient fibroblasts with Npas2 siRNA knockdown","pmids":["26895328"],"confidence":"High","gaps":["Whether NPAS2 drives identical or distinct target gene repertoires compared to CLOCK in peripheral tissues was not resolved"]},{"year":2017,"claim":"NPAS2 was linked to cell proliferation and tumor biology through direct transcriptional activation of CDC25A (promoting cell cycle progression) and to anxiety-related behavior through transcriptional regulation of GABA-A receptor subunit genes in the ventral striatum.","evidence":"ChIP, Co-IP, reporter assays, and xenograft models for CDC25A in hepatocellular carcinoma; KO and striatal knockdown with behavioral testing for GABA-A targets","pmids":["28333141","29163035"],"confidence":"Medium","gaps":["Whether CDC25A regulation by NPAS2 is circadian or constitutive was not determined","The specific E-box elements in Gabra genes bound by NPAS2 were not mapped"]},{"year":2019,"claim":"Cell-type-specific manipulation demonstrated that NPAS2 in D1R-MSNs (but not D2R-MSNs) controls excitatory synaptic strength and cocaine-induced synaptic potentiation, while tissue-specific studies identified HES1 and HIF-1α as direct NPAS2 targets linking the circadian clock to Notch signaling, fibrogenesis, and metabolic reprogramming.","evidence":"Cre-inducible cell-type-specific shRNA with electrophysiology in D1R vs. D2R MSNs; ChIP and reporter assays for HES1 in hepatic stellate cells and HIF-1α in hepatocellular carcinoma cells with in vivo models","pmids":["30962277","31778954","31765736"],"confidence":"High","gaps":["How NPAS2 loss increases excitatory drive in D1R-MSNs at the transcriptional target level was not fully elucidated","Whether HIF-1α activation by NPAS2 is E-box-dependent or involves an indirect mechanism was not definitively shown"]},{"year":2022,"claim":"NPAS2 was found to physically interact with SIRT1 in the nucleus accumbens, sharing transcriptional targets in reward and metabolic pathways, and to directly activate hepatic CYP1A2 transcription via an E-box-like element, extending the NPAS2 target repertoire to drug metabolism and NAD+-dependent epigenetic regulation.","evidence":"Co-IP and ChIP-seq cross-analysis with behavioral epistasis for SIRT1 interaction; Npas2-KO mice with ChIP-seq, reporter assays, and pharmacokinetic studies for CYP1A2","pmids":["35001440","36379250"],"confidence":"High","gaps":["Whether SIRT1 deacetylates NPAS2 or BMAL1 in the NPAS2:BMAL1 complex specifically was not tested","The full hepatic NPAS2 cistrome remains incompletely defined"]},{"year":2025,"claim":"Post-transcriptional regulation of Npas2 mRNA by m6A modification was identified: FTO-mediated demethylation destabilizes Npas2 mRNA via PRRC2A, and loss of this suppression elevates NPAS2 to activate HIF-1α-driven glycolysis in macrophages, linking epitranscriptomic regulation of NPAS2 to innate immune metabolic reprogramming.","evidence":"MeRIP-seq, loss/gain-of-function of FTO and NPAS2 in bone marrow-derived macrophages, db/db mouse diabetic nephropathy model","pmids":["39831513"],"confidence":"Medium","gaps":["Whether m6A regulation of Npas2 mRNA occurs in other cell types or is macrophage-specific was not addressed","The specific m6A sites on Npas2 mRNA were not individually validated by site-directed mutagenesis"]},{"year":2026,"claim":"NPAS2 in medial prefrontal cortex was shown to orchestrate afternoon nap behavior by transcriptionally activating POU2F2, which represses tyrosine hydroxylase to suppress dopamine synthesis in TH+ mPFC neurons, establishing a circadian transcriptional cascade governing daytime sleep architecture.","evidence":"ChIP and reporter assays defining NPAS2→POU2F2→TH pathway, region-specific viral NPAS2 manipulation with in vivo nap monitoring and TH+ neuron electrophysiology","pmids":["41839866"],"confidence":"Medium","gaps":["Whether the NPAS2→POU2F2→TH axis operates in other dopaminergic brain regions is unknown","The contribution of BMAL1 to this mPFC-specific function was not tested"]},{"year":null,"claim":"Key unresolved questions include: (1) the crystal or cryo-EM structure of heme-bound NPAS2, alone and in complex with BMAL1 on DNA; (2) the molecular mechanism by which NAD(P)H enhances DNA binding through the bHLH domain; (3) how NPAS2 and CLOCK achieve tissue-specific or target-specific selectivity despite apparent redundancy; and (4) whether the diverse non-circadian functions of NPAS2 (cell cycle, fibrosis, metabolic reprogramming) operate through canonical E-box-dependent BMAL1 heterodimerization or through distinct mechanisms.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of any NPAS2 domain in complex with BMAL1","NAD(P)H-binding site within bHLH residues 1–61 is structurally undefined","Tissue-specific NPAS2 vs. CLOCK cistrome comparison is lacking","Whether NPAS2 can function independently of BMAL1 in any context is untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[1,11,19,21,24,29,32]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0,2,9,13,15]},{"term_id":"GO:0140299","term_label":"molecular sensor activity","supporting_discovery_ids":[0,2,15]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1,6,13,19]}],"pathway":[{"term_id":"R-HSA-9909396","term_label":"Circadian clock","supporting_discovery_ids":[1,4,7,11,12,13,14,16,29]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,1,9,19,21,24,29,32]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[3,19,22,25,32]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[5,23,26]}],"complexes":["NPAS2:BMAL1 heterodimer"],"partners":["BMAL1","CRY1","CRY2","SIRT1","RARA","RXRA","ARNTL2","PER2"],"other_free_text":[]},"mechanistic_narrative":"NPAS2 is a heme-binding bHLH-PAS transcription factor that functions as a core component of the mammalian circadian clock, with a predominant role in forebrain and peripheral tissues where it operates redundantly with CLOCK. NPAS2 forms an obligate heterodimer with BMAL1 to activate transcription of circadian and tissue-specific target genes (Per1, Per2, Cry1, Dbp, Drd3, CYP1A2, CDC25A, HES1, CX3CL1, Aanat) through E-box elements; its DNA-binding activity is enhanced by reduced NAD(P)H cofactors sensed via the N-terminal bHLH domain and inhibited by carbon monoxide binding to heme coordinated by His119/His171 in the PAS-A domain, while CRY proteins stabilize unphosphorylated NPAS2 and RORα/REV-ERBα regulate Npas2 transcription itself via ROR-response elements [PMID:11441146, PMID:12446832, PMID:22245004, PMID:16628007, PMID:20817722]. In the nucleus accumbens, NPAS2 is selectively expressed in D1R-positive medium spiny neurons where it controls dopamine receptor (Drd3) expression, GABAergic signaling (Gabra1), and excitatory synaptic plasticity to regulate cocaine reward sensitivity and anxiety-like behavior [PMID:25444159, PMID:30962277, PMID:29163035]. NPAS2-deficient mice exhibit impaired long-term memory, disrupted non-rapid-eye-movement sleep homeostasis, loss of food-entrainable circadian behavior, and attenuated cortical Per2 oscillations, establishing NPAS2 as a critical regulator of sleep, memory, and behavioral rhythmicity [PMID:10864874, PMID:12843397, PMID:16636276]."},"prefetch_data":{"uniprot":{"accession":"Q99743","full_name":"Neuronal PAS domain-containing protein 2","aliases":["Basic-helix-loop-helix-PAS protein MOP4","Class E basic helix-loop-helix protein 9","bHLHe9","Member of PAS protein 4","PAS domain-containing protein 4"],"length_aa":824,"mass_kda":91.8,"function":"Transcriptional activator which forms a core component of the circadian clock. The circadian clock, an internal time-keeping system, regulates various physiological processes through the generation of approximately 24 hour circadian rhythms in gene expression, which are translated into rhythms in metabolism and behavior. It is derived from the Latin roots 'circa' (about) and 'diem' (day) and acts as an important regulator of a wide array of physiological functions including metabolism, sleep, body temperature, blood pressure, endocrine, immune, cardiovascular, and renal function. Consists of two major components: the central clock, residing in the suprachiasmatic nucleus (SCN) of the brain, and the peripheral clocks that are present in nearly every tissue and organ system. Both the central and peripheral clocks can be reset by environmental cues, also known as Zeitgebers (German for 'timegivers'). The predominant Zeitgeber for the central clock is light, which is sensed by retina and signals directly to the SCN. The central clock entrains the peripheral clocks through neuronal and hormonal signals, body temperature and feeding-related cues, aligning all clocks with the external light/dark cycle. Circadian rhythms allow an organism to achieve temporal homeostasis with its environment at the molecular level by regulating gene expression to create a peak of protein expression once every 24 hours to control when a particular physiological process is most active with respect to the solar day. Transcription and translation of core clock components (CLOCK, NPAS2, BMAL1, BMAL2, PER1, PER2, PER3, CRY1 and CRY2) plays a critical role in rhythm generation, whereas delays imposed by post-translational modifications (PTMs) are important for determining the period (tau) of the rhythms (tau refers to the period of a rhythm and is the length, in time, of one complete cycle). A diurnal rhythm is synchronized with the day/night cycle, while the ultradian and infradian rhythms have a period shorter and longer than 24 hours, respectively. Disruptions in the circadian rhythms contribute to the pathology of cardiovascular diseases, cancer, metabolic syndromes and aging. A transcription/translation feedback loop (TTFL) forms the core of the molecular circadian clock mechanism. Transcription factors, CLOCK or NPAS2 and BMAL1 or BMAL2, form the positive limb of the feedback loop, act in the form of a heterodimer and activate the transcription of core clock genes and clock-controlled genes (involved in key metabolic processes), harboring E-box elements (5'-CACGTG-3') within their promoters. The core clock genes: PER1/2/3 and CRY1/2 which are transcriptional repressors form the negative limb of the feedback loop and interact with the CLOCK|NPAS2-BMAL1|BMAL2 heterodimer inhibiting its activity and thereby negatively regulating their own expression. This heterodimer also activates nuclear receptors NR1D1/2 and RORA/B/G, which form a second feedback loop and which activate and repress BMAL1 transcription, respectively. The NPAS2-BMAL1 heterodimer positively regulates the expression of MAOA, F7 and LDHA and modulates the circadian rhythm of daytime contrast sensitivity by regulating the rhythmic expression of adenylate cyclase type 1 (ADCY1) in the retina. NPAS2 plays an important role in sleep homeostasis and in maintaining circadian behaviors in normal light/dark and feeding conditions and in the effective synchronization of feeding behavior with scheduled food availability. Regulates the gene transcription of key metabolic pathways in the liver and is involved in DNA damage response by regulating several cell cycle and DNA repair genes. Controls the circadian rhythm of NR0B2 expression by binding rhythmically to its promoter (By similarity). Mediates the diurnal variation in the expression of GABARA1 receptor in the brain and contributes to the regulation of anxiety-like behaviors and GABAergic neurotransmission in the ventral striatum (By similarity)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q99743/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/NPAS2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/NPAS2","total_profiled":1310},"omim":[{"mim_id":"612975","title":"SHORT SLEEP, FAMILIAL NATURAL, 1; FNSS1","url":"https://www.omim.org/entry/612975"},{"mim_id":"606200","title":"BASIC HELIX-LOOP-HELIX FAMILY, MEMBER E41; BHLHE41","url":"https://www.omim.org/entry/606200"},{"mim_id":"605339","title":"FMR1 AUTOSOMAL HOMOLOG 2; FXR2","url":"https://www.omim.org/entry/605339"},{"mim_id":"605327","title":"NUCLEAR FACTOR, INTERLEUKIN 3-REGULATED; NFIL3","url":"https://www.omim.org/entry/605327"},{"mim_id":"604256","title":"BASIC HELIX-LOOP-HELIX FAMILY, MEMBER E40; BHLHE40","url":"https://www.omim.org/entry/604256"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/NPAS2"},"hgnc":{"alias_symbol":["MOP4","PASD4","bHLHe9"],"prev_symbol":[]},"alphafold":{"accession":"Q99743","domains":[{"cath_id":"4.10.280.10","chopping":"1-67","consensus_level":"medium","plddt":86.8472,"start":1,"end":67},{"cath_id":"3.30.450.20","chopping":"94-199_222-236","consensus_level":"high","plddt":85.6584,"start":94,"end":236},{"cath_id":"3.30.450.20","chopping":"249-364","consensus_level":"high","plddt":95.433,"start":249,"end":364}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q99743","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q99743-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q99743-F1-predicted_aligned_error_v6.png","plddt_mean":60.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=NPAS2","jax_strain_url":"https://www.jax.org/strain/search?query=NPAS2"},"sequence":{"accession":"Q99743","fasta_url":"https://rest.uniprot.org/uniprotkb/Q99743.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q99743/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q99743"}},"corpus_meta":[{"pmid":"11441146","id":"PMC_11441146","title":"Regulation 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sciences","url":"https://pubmed.ncbi.nlm.nih.gov/26388558","citation_count":8,"is_preprint":false},{"pmid":"37406788","id":"PMC_37406788","title":"Downregulation of a potential therapeutic target NPAS2, regulated by p53, alleviates pulmonary fibrosis by inhibiting epithelial-mesenchymal transition via suppressing HES1.","date":"2023","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/37406788","citation_count":8,"is_preprint":false},{"pmid":"34460437","id":"PMC_34460437","title":"NPAS2 ameliorates myocardial ischaemia/reperfusion injury in rats via CX3CL1 pathways and regulating autophagy.","date":"2021","source":"Aging","url":"https://pubmed.ncbi.nlm.nih.gov/34460437","citation_count":7,"is_preprint":false},{"pmid":"37120564","id":"PMC_37120564","title":"Characterization of molecular subtypes based on chromatin regulators and identification of the role of NPAS2 in lung adenocarcinoma.","date":"2023","source":"Clinical epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/37120564","citation_count":7,"is_preprint":false},{"pmid":"21140207","id":"PMC_21140207","title":"A variant affecting miRNAs binding in the circadian gene Neuronal PAS domain protein 2 (NPAS2) is not associated with breast cancer risk.","date":"2010","source":"Breast cancer research and treatment","url":"https://pubmed.ncbi.nlm.nih.gov/21140207","citation_count":7,"is_preprint":false},{"pmid":"39495286","id":"PMC_39495286","title":"Ellagic Acid Protects against Alcohol-Related Liver Disease by Modulating the Hepatic Circadian Rhythm Signaling through the Gut Microbiota-NPAS2 Axis.","date":"2024","source":"Journal of agricultural and food chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/39495286","citation_count":6,"is_preprint":false},{"pmid":"24196956","id":"PMC_24196956","title":"Nuclear receptor-mediated cell-autonomous oscillatory expression of the circadian transcription factor, neuronal PAS domain protein 2 (NPAS2).","date":"2013","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/24196956","citation_count":6,"is_preprint":false},{"pmid":"26221256","id":"PMC_26221256","title":"Current evidence on the relationship between two common polymorphisms in NPAS2 gene and cancer risk.","date":"2015","source":"International journal of clinical and experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/26221256","citation_count":5,"is_preprint":false},{"pmid":"38584327","id":"PMC_38584327","title":"NPAS2, transcriptionally activated by ARRB1, promotes the malignant behaviours of lung adenocarcinoma cells and regulates the reprogramming of glucose metabolism.","date":"2024","source":"Clinical and experimental pharmacology & physiology","url":"https://pubmed.ncbi.nlm.nih.gov/38584327","citation_count":5,"is_preprint":false},{"pmid":"37328030","id":"PMC_37328030","title":"Thyroid-stimulating hormone-thyroid hormone signaling contributes to circadian regulation through repressing clock2/npas2 in zebrafish.","date":"2023","source":"Journal of genetics and genomics = Yi chuan xue bao","url":"https://pubmed.ncbi.nlm.nih.gov/37328030","citation_count":4,"is_preprint":false},{"pmid":"29355377","id":"PMC_29355377","title":"Prefrontal cortex and dorsomedial hypothalamus mediate food reward-induced effects via npas2 and egr1 expression in rat.","date":"2017","source":"Physiological research","url":"https://pubmed.ncbi.nlm.nih.gov/29355377","citation_count":3,"is_preprint":false},{"pmid":"40820553","id":"PMC_40820553","title":"NPAS2 Deficiency Leads to Antidepressant-Like Behaviors in Mice by Modulating Astrocyte-Mediated Neuroinflammation.","date":"2025","source":"Journal of pineal research","url":"https://pubmed.ncbi.nlm.nih.gov/40820553","citation_count":1,"is_preprint":false},{"pmid":"40476504","id":"PMC_40476504","title":"Circadian gene NPAS2 modulates pain sensitization in CFA-induced inflammatory pain model.","date":"2025","source":"Molecular 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international","url":"https://pubmed.ncbi.nlm.nih.gov/41020491","citation_count":0,"is_preprint":false},{"pmid":"41839866","id":"PMC_41839866","title":"Impact of NPAS2 on mPFC dopamine synthesis and nap behavior.","date":"2026","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/41839866","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.09.23.677952","title":"NPAS2 attenuates VSMC phenotypic switching in ascending thoracic aortic aneurysm via LPCAT3/PC-PUFA2S-mediated ferroptosis","date":"2025-09-25","source":"bioRxiv","url":"https://doi.org/10.1101/2025.09.23.677952","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":40697,"output_tokens":7895,"usd":0.120258},"stage2":{"model":"claude-opus-4-6","input_tokens":11712,"output_tokens":5274,"usd":0.285615},"total_usd":0.405873,"stage1_batch_id":"msgbatch_012ZiiCUBfB62NCTQd4Bk1Jo","stage2_batch_id":"msgbatch_01Xuqq9aUHoQouS7UVGZNStZ","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2001,\n      \"finding\": \"NPAS2 forms an obligate heterodimer with BMAL1, and the DNA-binding activity of the NPAS2:BMAL1 heterodimer is strongly enhanced by reduced NAD cofactors (NADH and NADPH) and inhibited by their oxidized forms in a purified (cell-free) system.\",\n      \"method\": \"In vitro DNA-binding assay with purified proteins and NAD cofactors\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with purified proteins, replicated across CLOCK:BMAL1 and NPAS2:BMAL1 heterodimers\",\n      \"pmids\": [\"11441146\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"NPAS2:BMAL1 heterodimer functions as a transcriptional activator of Per1, Per2, and Cry1 genes (via E-box elements) and represses BMAL1, establishing NPAS2 as a component of the circadian transcriptional feedback loop operative in the mammalian forebrain. Per2 mRNA oscillation in frontal cortex is abolished in NPAS2-deficient mice.\",\n      \"method\": \"Conditional induction system in neuroblastoma cells, DNA microarrays, Northern blotting, in situ hybridization in NPAS2-knockout mice\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods in cell lines and knockout mice, replicated in vivo\",\n      \"pmids\": [\"11441147\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Both PAS-A and PAS-B domains of NPAS2 bind heme as a prosthetic group; heme-loaded (holo) NPAS2:BMAL1 heterodimers bind DNA avidly under reducing conditions, but low micromolar CO inhibits DNA binding of holo-NPAS2 and promotes formation of inactive BMAL1 homodimers at the expense of NPAS2:BMAL1 heterodimers.\",\n      \"method\": \"In vitro DNA-binding assay, spectroscopy, heme-binding biochemistry with apo and holo NPAS2 proteins\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with defined apo/holo states and gas treatment, multiple orthogonal methods\",\n      \"pmids\": [\"12446832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"NPAS2 is a bHLH-PAS transcription factor whose expression is spatiotemporally coincident with formation of the frontal association/limbic forebrain pathway; NPAS2-deficient mice exhibit deficits in long-term memory in cued and contextual fear tasks, indicating a dedicated regulatory role in memory acquisition.\",\n      \"method\": \"Targeted lacZ knock-in, behavioral testing (cued and contextual fear conditioning) in knockout mice\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with specific behavioral phenotype, well-controlled study\",\n      \"pmids\": [\"10864874\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"NPAS2 plays a substantive role in maintaining circadian locomotor behaviors under normal light-dark and feeding conditions and is critical for food-entrainment adaptability, as shown by disrupted behavioral rhythms and impaired adaptation to restricted feeding schedules in NPAS2-deficient mice.\",\n      \"method\": \"Locomotor activity monitoring, sleep EEG, restricted food-driven entrainment assays in NPAS2-knockout mice\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with multiple defined behavioral phenotypes, replicated across conditions\",\n      \"pmids\": [\"12843397\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Nuclear receptors RARα and RXRα interact with NPAS2 (MOP4) and negatively regulate CLOCK/MOP4:BMAL1-mediated transcriptional activation of clock gene expression in vascular cells; retinoic acid can phase-shift Per2 mRNA rhythmicity in vivo.\",\n      \"method\": \"Co-immunoprecipitation, reporter gene assays, in vivo retinoic acid treatment\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal interaction shown and functional consequence measured, single lab\",\n      \"pmids\": [\"11439184\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CRY proteins stabilize unphosphorylated forms of CLOCK(NPAS2) and BMAL1 and cause their nuclear accumulation, inhibiting transcriptional activity without disrupting complex formation or DNA binding; this posttranslational regulation is CRY-specific and is confirmed in Cry double-knockout mice.\",\n      \"method\": \"Ectopic co-expression, immunofluorescence, Western blot of phosphorylation states, reporter assays, Cry double-KO mouse tissues\",\n      \"journal\": \"Cell cycle\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods in cells and confirmed in vivo, single lab\",\n      \"pmids\": [\"16628007\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"NPAS2 acts as a transcriptional regulator of non-rapid eye movement sleep homeostasis in a sex-dependent manner; in npas2-/- mice, sleep spindle EEG activity is reduced, delta frequency shifts, and the wake-dependent increase in cortical Per2 expression after sleep deprivation is attenuated, implying NPAS2 drives Per2 transcription in cortex in response to sleep pressure.\",\n      \"method\": \"EEG/EMG recording, sleep deprivation protocol, cortical Per2 mRNA measurement in npas2-/- mice\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with multiple EEG and molecular phenotypes, replicated across sex conditions\",\n      \"pmids\": [\"16636276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The heme-bound bHLH-PAS-A domain of NPAS2 exists predominantly as a dimer; the bHLH domain assists stable heme binding (rate constant >100-fold higher than isolated PAS-A alone) and is required for E-box DNA binding in the presence of heme, as shown by quartz-crystal microbalance and spectroscopic analysis.\",\n      \"method\": \"Optical absorption and resonance Raman spectroscopy, heme-binding kinetics, quartz-crystal microbalance DNA-binding assay\",\n      \"journal\": \"FEBS Journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple in vitro biophysical and biochemical methods with domain-deletion analysis\",\n      \"pmids\": [\"16704425\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Mutation of the heme axial ligands His119 or His171 in the NPAS2 PAS-A domain impairs heterodimer formation with BMAL1 and abolishes DNA binding to the E-box, demonstrating that heme coordination is required for NPAS2 transcriptional activity.\",\n      \"method\": \"Site-directed mutagenesis of full-length NPAS2, reporter gene (Per1 promoter) assay in NIH3T3 cells, gel-shift assay with isolated bHLH-PAS-A domain\",\n      \"journal\": \"Biochemical and Biophysical Research Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — active-site mutagenesis combined with DNA-binding and transcriptional assays\",\n      \"pmids\": [\"18230344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Interaction of the PAS-A domain with the bHLH domain of NPAS2 shifts heme axial coordination from a Cys170/His119 equilibrium (isolated PAS-A) to a His119/His171 (bis-His) coordination; His119 and His171 are the functional axial ligands in the bHLH-PAS-A context.\",\n      \"method\": \"Resonance Raman spectroscopy of His and Cys mutants of bHLH-PAS-A domain\",\n      \"journal\": \"Journal of Inorganic Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — systematic mutagenesis + resonance Raman spectroscopy establishing coordination structure\",\n      \"pmids\": [\"22245004\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"NPAS2 and CLOCK have overlapping, redundant roles in circadian transcription of Factor VII in the liver; FVII mRNA rhythms are abolished only in Clock-/-;Npas2-/- double-knockout mice but are robust in each single knockout, and both NPAS2:BMAL1 and CLOCK:BMAL1 activate FVII transcription ~4-fold via E-box elements, with this activation suppressed by PER2 and CRY1.\",\n      \"method\": \"Double-knockout mouse genetics, reporter gene assays, E-box mutagenesis, plasma FVII measurement\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — genetic epistasis with reporter assays and mutagenesis, in vivo and in vitro\",\n      \"pmids\": [\"18316400\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"NPAS2 is a direct transcriptional target of RORα and REV-ERBα; both nuclear receptors occupy the NPAS2 promoter at two functional ROR-response elements (ROREs) identified by ChIP/microarray, and both regulate NPAS2 mRNA expression, coordinating the positive arm of the circadian feedback loop.\",\n      \"method\": \"ChIP/microarray (ChIP-on-chip), luciferase reporter assays with RORE mutants, RT-PCR\",\n      \"journal\": \"Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — ChIP-on-chip plus functional reporter mutagenesis, two nuclear receptors validated\",\n      \"pmids\": [\"20817722\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"NPAS2 and BMAL1 bind to E-box sequences of Per2, Cry1, Dbp, and Per1 in the mouse cerebral cortex in a time-of-day-dependent manner (peak ~ZT6); sleep deprivation decreases NPAS2:BMAL1 binding to Per2 despite increasing Per2 mRNA, and decreases CLOCK:BMAL1 binding to Dbp consistent with reduced Dbp mRNA.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) at multiple zeitgeber times in cerebral cortex, qPCR\",\n      \"journal\": \"PLoS ONE\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct ChIP in vivo at multiple time points and after sleep deprivation, single lab\",\n      \"pmids\": [\"22039518\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"NPAS2 can compensate for loss of CLOCK in peripheral circadian oscillators (fibroblasts) as well as SCN neurons; knockdown of Npas2 in CLOCK-deficient fibroblasts causes arrhythmicity, demonstrating that NPAS2 sustains autonomous circadian rhythms in peripheral cells.\",\n      \"method\": \"Single-cell bioluminescence imaging of PER2::LUC in CLOCK-deficient fibroblasts with Npas2 siRNA knockdown, luminometry\",\n      \"journal\": \"PLoS Genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic complementation and siRNA knockdown with real-time imaging, clear molecular phenotype\",\n      \"pmids\": [\"26895328\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"NAD(P)H enhances NPAS2:BMAL1 DNA binding specifically; the N-terminal 1–61 residues of NPAS2 (within the bHLH domain) are sufficient to sense NAD(P)H and mediate this enhancement; NAD(P)+ does not inhibit NPAS2 binding under these assay conditions.\",\n      \"method\": \"Electrophoretic mobility shift assay (EMSA) with truncation mutants of NPAS2 bHLH domain and various NAD derivatives\",\n      \"journal\": \"Biochemical and Biophysical Research Communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro assay with systematic truncation mutants, single lab\",\n      \"pmids\": [\"23831463\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Cell-autonomous circadian transcription of the Npas2 gene requires a specific RORE in its upstream promoter and endogenous RORα; dominant-negative RORα, RORα siRNA, and RORα-mutant (sg/sg) mouse embryonic fibroblasts all display damped Npas2 transcriptional oscillations.\",\n      \"method\": \"RORE promoter mutagenesis, dominant-negative and siRNA constructs, RORα-mutant mouse fibroblasts, luciferase reporter\",\n      \"journal\": \"Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — promoter mutagenesis, multiple genetic tools, and in vivo confirmation in mutant mice\",\n      \"pmids\": [\"24196956\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"RNA interference-mediated knockdown of NPAS2 in human cells impairs cell cycle delay in response to mutagen treatment and reduces DNA repair capacity (comet assay); a PCR expression array shows that NPAS2 knockdown represses several cell cycle and DNA repair genes.\",\n      \"method\": \"RNAi knockdown, comet assay, cell cycle analysis, pathway-based PCR expression array\",\n      \"journal\": \"Molecular Cancer Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple assays in KD cells, single lab, functional consequence defined\",\n      \"pmids\": [\"18819933\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Genome-wide ChIP-on-chip identified 26 genomic loci bound by NPAS2 in MCF-7 cells; 16 were confirmed by qPCR, including cancer-related targets ARHGAP29, CDC25A, CDKN2AIP, CX3CL1, ELF4, GNAL, KDELR1, POU4F2, and THRA.\",\n      \"method\": \"ChIP-on-chip (genome-wide), confirmatory real-time PCR\",\n      \"journal\": \"Cancer Letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genome-wide ChIP with PCR validation, single lab\",\n      \"pmids\": [\"19457610\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"NPAS2 directly transcriptionally activates the Drd3 dopamine receptor gene in the nucleus accumbens (NAc); NPAS2 expression is restricted to Drd1+ neurons in NAc; NPAS2 knockdown in NAc reduces cocaine conditioned place preference and disrupts the diurnal rhythm of Drd3 expression.\",\n      \"method\": \"AAV-shRNA knockdown in NAc, ChIP-seq, conditioned place preference, cell sorting qRT-PCR\",\n      \"journal\": \"Biological Psychiatry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — ChIP-seq identifies direct binding, viral knockdown with behavioral and molecular phenotypes, orthogonal methods\",\n      \"pmids\": [\"25444159\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Both CLOCK and NPAS2 bind the Aanat promoter E-box in chicken photoreceptors (ChIP); NPAS2 knockdown damps the circadian rhythm of Aanat mRNA, while CLOCK knockdown reduces Npas2 expression, demonstrating overlapping roles with CLOCK as the dominant regulator of the photoreceptor clockwork.\",\n      \"method\": \"Gene-specific miRNA knockdown vectors in photoreceptor cell cultures, ChIP, circadian mRNA measurements\",\n      \"journal\": \"Journal of Neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP shows direct binding, knockdown shows functional redundancy, avian model\",\n      \"pmids\": [\"20345751\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"NPAS2 heterodimerizes with BMAL1 to bind the E-box element in the CDC25A promoter and transcriptionally upregulates CDC25A phosphatase, which drives CDK2/4/6 dephosphorylation (promoting cell proliferation) and Bcl-2 upregulation (inhibiting apoptosis) in hepatocellular carcinoma cells.\",\n      \"method\": \"Co-immunoprecipitation, ChIP, luciferase reporter assay, overexpression/knockdown with cell cycle and apoptosis readouts, xenograft in vivo\",\n      \"journal\": \"Cell Death & Disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP and Co-IP with functional rescue experiments, single lab\",\n      \"pmids\": [\"28333141\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"NPAS2 regulates anxiety-like behavior through transcriptional control of Gabra (GABA-A receptor subunit) genes in the ventral striatum; Npas2 null mutant mice show reduced anxiety and decreased sensitivity to diazepam, and NAc-specific Npas2 knockdown reduces Gabra1 expression.\",\n      \"method\": \"Global Npas2 null mutant behavioral testing (elevated plus maze, light/dark box, open field), AAV-shRNA striatal knockdown, acute/chronic stress Npas2 expression measurement\",\n      \"journal\": \"Frontiers in Molecular Neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO and region-specific knockdown with behavioral and molecular phenotypes, single lab\",\n      \"pmids\": [\"29163035\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"NPAS2 directly transcriptionally activates HIF-1α, which mediates upregulation of glycolytic genes (GLUT1, HK2, GPI, ALDOA, ENO2, PKM2, MCT4) and downregulation of PGC-1α/mitochondrial biogenesis in hepatocellular carcinoma cells, promoting the Warburg effect.\",\n      \"method\": \"Overexpression/knockdown of NPAS2, luciferase reporter assays, ChIP, in vitro and xenograft in vivo metabolic assays\",\n      \"journal\": \"Cancer Letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP with reporter assays and functional metabolic rescue, single lab\",\n      \"pmids\": [\"31765736\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"NPAS2 directly transcriptionally activates Hes1 (a Notch signaling target) in hepatic stellate cells, promoting liver fibrogenesis; NPAS2 is upregulated in hepatic stellate cells after fibrogenic injury.\",\n      \"method\": \"Luciferase reporter assay, ChIP, NPAS2 overexpression/knockdown in hepatic stellate cells, in vivo fibrosis model\",\n      \"journal\": \"Molecular Therapy: Nucleic Acids\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP and reporter assays with in vivo fibrosis confirmation, single lab\",\n      \"pmids\": [\"31778954\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"NPAS2 regulates excitatory synaptic transmission specifically in D1R-expressing medium spiny neurons (MSNs) of the nucleus accumbens; cell-type-specific Npas2 knockdown in D1R-MSNs (but not D2R-MSNs) increases excitatory drive, blocks cocaine-induced synaptic potentiation, and reduces cocaine conditioned place preference.\",\n      \"method\": \"Viral-mediated cell-type-specific Npas2 knockdown with Cre-inducible shRNA, electrophysiology (mEPSC), conditioned place preference in Drd1a-tdTomato mice\",\n      \"journal\": \"Journal of Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — cell-type-specific genetic manipulation with electrophysiology and behavior, orthogonal methods\",\n      \"pmids\": [\"30962277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"NPAS2 interacts with CRY2 by co-immunoprecipitation and directly activates the CX3CL1 promoter; overexpression of NPAS2 upregulates CX3CL1, which activates the downstream AKT/mTOR pathway to inhibit autophagy and protect against cardiomyocyte apoptosis from hypoxia/reoxygenation injury.\",\n      \"method\": \"Co-immunoprecipitation, luciferase reporter assay (CX3CL1 promoter), overexpression in cardiomyocytes, in vivo rat I/R model\",\n      \"journal\": \"Aging\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP plus reporter assay, in vivo confirmation, single lab\",\n      \"pmids\": [\"34460437\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ARNTL2/NPAS2 forms a heterodimeric complex that induces PER3 and DBP expression, but is a weaker inducer than the canonical ARNTL/NPAS2 dimer; DEC2 blocks ARNTL2/NPAS2-driven expression; TNF promotes nuclear localization of ARNTL2 and induces ARNTL2 and NPAS2 via NF-κB signaling.\",\n      \"method\": \"Transfection of cloned constructs in HEK293, RT-qPCR, immunofluorescence staining, NF-κB pathway inhibitor (IKK-2 inhibitor IMD-0354)\",\n      \"journal\": \"Journal of Circadian Rhythms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — transfection/reporter approach with pharmacological inhibition, single lab\",\n      \"pmids\": [\"30210560\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"NPAS2 and SIRT1 physically interact (co-immunoprecipitation) in the mouse nucleus accumbens; both show diurnal expression regulated by NAD+; they share transcriptional targets enriched in reward and metabolic pathways (cross-ChIP-seq analysis); NAc-specific Npas2 knockdown or functional Npas2 mutation attenuates SIRT1-mediated increases in cocaine preference.\",\n      \"method\": \"Co-immunoprecipitation, diurnal NAD+ measurement, ChIP-seq cross-analysis, AAV-shRNA NAc knockdown, cocaine conditioned place preference\",\n      \"journal\": \"European Journal of Neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus ChIP-seq plus behavioral rescue, single lab\",\n      \"pmids\": [\"35001440\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"NPAS2 transcriptionally activates hepatic CYP1A2 by binding to an E-box-like element at −416 bp in the Cyp1a2 promoter; Npas2 knockout mice show decreased CYP1A2 mRNA, protein, and enzymatic activity with loss of diurnal rhythmicity.\",\n      \"method\": \"Npas2-/- knockout mice, luciferase reporter assay, ChIP-seq, in vivo pharmacokinetic (theophylline/phenacetin) assays\",\n      \"journal\": \"Biochemical Pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — ChIP-seq with reporter mutagenesis and in vivo enzymatic confirmation in KO mice\",\n      \"pmids\": [\"36379250\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"p53 transcriptionally activates NPAS2 in alveolar type II epithelial cells; NPAS2 in turn promotes epithelial-mesenchymal transition (EMT) by transcriptionally upregulating HES1, and NPAS2 overexpression partially rescues the anti-EMT effects of TP53 knockdown.\",\n      \"method\": \"Bleomycin-induced fibrosis mouse model, siRNA knockdown, overexpression, luciferase reporter assay, in vitro EMT assays\",\n      \"journal\": \"Cellular Signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reporter assay showing p53→NPAS2→HES1 axis, functional rescue experiments, single lab\",\n      \"pmids\": [\"37406788\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In macrophages, FTO (m6A demethylase) reduces m6A modification on Npas2 mRNA through a PRRC2A-dependent mechanism, decreasing Npas2 stability; loss of this suppression leads to elevated NPAS2, which activates HIF-1α signaling to promote glycolysis and M1 macrophage activation in diabetic nephropathy.\",\n      \"method\": \"MeRIP-seq, transcriptome analysis, loss/gain-of-function of FTO and NPAS2 in bone marrow-derived macrophages, db/db mouse model\",\n      \"journal\": \"FASEB Journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — MeRIP-seq identifies m6A site, functional epistasis in cells and in vivo, single lab\",\n      \"pmids\": [\"39831513\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"mPFC-expressed NPAS2 orchestrates afternoon nap behavior by circadian suppression of dopamine synthesis: NPAS2 transcriptionally activates the repressor POU2F2, which downregulates tyrosine hydroxylase (TH) expression and dopamine production in TH+ mPFC neurons, reducing their wake-promoting activity during nap hours.\",\n      \"method\": \"In vivo sleep/nap monitoring, ChIP, luciferase reporter assay, viral-mediated region-specific NPAS2 manipulation, TH+ neuron electrophysiology in mice\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP and reporter assays defining NPAS2→POU2F2→TH pathway, region-specific manipulation with behavioral and neuronal activity readouts, single lab\",\n      \"pmids\": [\"41839866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"NPAS2 transcriptionally represses LPCAT3 expression in vascular smooth muscle cells (VSMCs); loss of NPAS2 elevates LPCAT3 and accumulation of phosphatidylcholines with two polyunsaturated fatty acyl chains (PC-PUFA2S), promoting ferroptosis-induced VSMC phenotypic switching and ascending thoracic aortic aneurysm progression.\",\n      \"method\": \"VSMC-specific Npas2 knockout mice, PDGF-BB treatment, ChIP/reporter assays, lipidomic analysis, ATAA mouse model\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — preprint, single lab, mechanistic model based on ChIP and KO phenotype\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"NPAS2 is a heme-binding, NAD(P)H-responsive, CO-sensitive bHLH-PAS transcription factor that forms obligate heterodimers with BMAL1 to activate circadian target genes (Per1, Per2, Cry1, Drd3, CYP1A2, CDC25A, HES1, CX3CL1, and others) via E-box elements; its transcriptional activity is regulated at multiple levels including redox state (NAD(P)H), gas sensing (CO via heme in PAS-A/B domains), CRY-mediated posttranslational stabilization, and RORα/REV-ERBα-dependent transcription of the Npas2 gene itself, while functionally it serves as the predominant circadian transcription factor in forebrain structures (especially nucleus accumbens) where it controls sleep homeostasis, memory, reward sensitivity, and anxiety by regulating dopamine receptor expression, GABAergic signaling, and synaptic plasticity in a cell-type- and sex-specific manner.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"NPAS2 is a heme-binding bHLH-PAS transcription factor that functions as a core component of the mammalian circadian clock, with a predominant role in forebrain and peripheral tissues where it operates redundantly with CLOCK. NPAS2 forms an obligate heterodimer with BMAL1 to activate transcription of circadian and tissue-specific target genes (Per1, Per2, Cry1, Dbp, Drd3, CYP1A2, CDC25A, HES1, CX3CL1, Aanat) through E-box elements; its DNA-binding activity is enhanced by reduced NAD(P)H cofactors sensed via the N-terminal bHLH domain and inhibited by carbon monoxide binding to heme coordinated by His119/His171 in the PAS-A domain, while CRY proteins stabilize unphosphorylated NPAS2 and RORα/REV-ERBα regulate Npas2 transcription itself via ROR-response elements [PMID:11441146, PMID:12446832, PMID:22245004, PMID:16628007, PMID:20817722]. In the nucleus accumbens, NPAS2 is selectively expressed in D1R-positive medium spiny neurons where it controls dopamine receptor (Drd3) expression, GABAergic signaling (Gabra1), and excitatory synaptic plasticity to regulate cocaine reward sensitivity and anxiety-like behavior [PMID:25444159, PMID:30962277, PMID:29163035]. NPAS2-deficient mice exhibit impaired long-term memory, disrupted non-rapid-eye-movement sleep homeostasis, loss of food-entrainable circadian behavior, and attenuated cortical Per2 oscillations, establishing NPAS2 as a critical regulator of sleep, memory, and behavioral rhythmicity [PMID:10864874, PMID:12843397, PMID:16636276].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"NPAS2 was established as a forebrain-enriched bHLH-PAS transcription factor required for long-term memory, revealing that this PAS-domain protein had dedicated neurological functions beyond a predicted role as a generic transcription factor.\",\n      \"evidence\": \"Targeted lacZ knock-in and behavioral testing (cued and contextual fear conditioning) in Npas2 knockout mice\",\n      \"pmids\": [\"10864874\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Transcriptional targets mediating the memory phenotype were unknown\", \"Whether NPAS2 functioned as a circadian factor in the brain was not addressed\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"NPAS2 was shown to heterodimerize with BMAL1 and function as a circadian transcription factor activating Per1, Per2, and Cry1 via E-box elements, with DNA-binding activity modulated by NAD(P)H redox state, linking metabolic sensing to the clock mechanism.\",\n      \"evidence\": \"In vitro DNA-binding assays with purified proteins and NAD cofactors; conditional induction system in neuroblastoma cells, microarrays, and Northern blotting; Per2 oscillation abolished in Npas2-KO forebrain\",\n      \"pmids\": [\"11441146\", \"11441147\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether NAD(P)H acted directly on NPAS2 or through an intermediary was unclear\", \"The heme-binding properties of NPAS2 had not been characterized\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Retinoic acid receptors RARα and RXRα were found to interact with NPAS2 and negatively regulate NPAS2:BMAL1-driven transcription, identifying a non-core-clock input pathway to circadian gene regulation in vascular cells.\",\n      \"evidence\": \"Co-immunoprecipitation, reporter gene assays, in vivo retinoic acid treatment shifting Per2 rhythms\",\n      \"pmids\": [\"11439184\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether RARα/RXRα regulation of NPAS2 occurs in vivo under physiological retinoid levels was not established\", \"The structural basis of the interaction was not defined\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Both PAS-A and PAS-B domains of NPAS2 were shown to bind heme, and carbon monoxide was identified as a gaseous signal that inhibits NPAS2:BMAL1 DNA binding and promotes inactive BMAL1 homodimers, establishing NPAS2 as a heme-based gas sensor.\",\n      \"evidence\": \"In vitro DNA-binding assays with apo/holo NPAS2 proteins, spectroscopy, and CO gas treatment\",\n      \"pmids\": [\"12446832\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The axial ligand identity for heme coordination was not resolved\", \"Whether CO regulation occurs at physiological intracellular concentrations in vivo was unknown\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"NPAS2 was established as functionally important for circadian locomotor behavior and food-entrainable rhythms in vivo, extending its role from a forebrain transcription factor to a bona fide circadian clock component regulating whole-organism behavioral outputs.\",\n      \"evidence\": \"Locomotor activity monitoring, sleep EEG, and restricted-feeding entrainment assays in Npas2-KO mice\",\n      \"pmids\": [\"12843397\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The degree of redundancy between NPAS2 and CLOCK in different tissues was not quantified\", \"Whether NPAS2 was required in the SCN or only in extra-SCN oscillators was unresolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Three advances refined the molecular mechanism: CRY proteins were shown to stabilize unphosphorylated NPAS2 and BMAL1 to repress transcription posttranslationally; NPAS2 was found to regulate NREM sleep homeostasis and cortical Per2 induction in a sex-dependent manner; and the bHLH domain was shown to be required for stable heme binding and E-box DNA recognition.\",\n      \"evidence\": \"Co-expression, phosphorylation analysis, and reporter assays in cells and Cry-DKO mice; EEG/EMG recording with sleep deprivation in Npas2-KO mice; resonance Raman spectroscopy and QCM DNA-binding assays with domain truncations\",\n      \"pmids\": [\"16628007\", \"16636276\", \"16704425\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How CRY inhibits transcription while preserving DNA binding was mechanistically unclear\", \"The identity of the functional heme axial ligands was still debated\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Site-directed mutagenesis of His119 and His171 in PAS-A proved these are the essential heme axial ligands required for BMAL1 heterodimerization and E-box DNA binding, while genetic studies demonstrated NPAS2 and CLOCK are functionally redundant in peripheral circadian transcription.\",\n      \"evidence\": \"Mutagenesis with Per1-reporter and gel-shift assays in NIH3T3; Clock/Npas2 double-KO mice with FVII rhythmic transcription analysis\",\n      \"pmids\": [\"18230344\", \"18316400\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether heme occupancy in vivo is limiting or constitutive was unknown\", \"The structural basis for NPAS2 vs. CLOCK interchangeability was not defined\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"NPAS2 knockdown in human cells impaired DNA damage-induced cell cycle arrest and repair capacity, suggesting a role for NPAS2 in genotoxic stress responses beyond circadian timekeeping.\",\n      \"evidence\": \"RNAi knockdown, comet assay, cell cycle analysis, and PCR expression array in human cells\",\n      \"pmids\": [\"18819933\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct transcriptional targets mediating DNA repair were not identified by ChIP\", \"Whether this function requires BMAL1 heterodimerization was not tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Npas2 itself was identified as a direct transcriptional target of RORα and REV-ERBα via functional ROR-response elements in its promoter, closing a regulatory loop between the auxiliary and core circadian feedback circuits.\",\n      \"evidence\": \"ChIP-on-chip, luciferase reporter assays with RORE mutants, RT-PCR; confirmed by RORE mutagenesis and RORα-mutant (sg/sg) fibroblasts\",\n      \"pmids\": [\"20817722\", \"24196956\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RORα- and REV-ERBα-mediated regulation of Npas2 is tissue-specific was not fully addressed\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Resonance Raman spectroscopy with systematic mutants resolved the heme coordination mechanism: interdomain interaction between bHLH and PAS-A switches axial ligation from a Cys170/His119 equilibrium to bis-His (His119/His171) coordination, finalizing the structural basis for gas sensing.\",\n      \"evidence\": \"Resonance Raman spectroscopy of His and Cys mutants of the bHLH-PAS-A domain\",\n      \"pmids\": [\"22245004\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No crystal structure of the heme-bound bHLH-PAS-A domain exists\", \"How CO binding induces the conformational change that disrupts BMAL1 interaction remains structurally unresolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"ChIP in mouse cerebral cortex demonstrated time-of-day-dependent NPAS2:BMAL1 occupancy at Per2, Cry1, Dbp, and Per1 E-boxes in vivo, with sleep deprivation paradoxically decreasing NPAS2 binding at Per2 despite increasing Per2 mRNA, revealing a dissociation between occupancy and transcript output under sleep pressure.\",\n      \"evidence\": \"Chromatin immunoprecipitation at multiple zeitgeber times in cerebral cortex with and without sleep deprivation\",\n      \"pmids\": [\"22039518\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The mechanism by which Per2 mRNA increases while NPAS2 binding decreases was not explained\", \"Cell-type resolution of cortical ChIP was lacking\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The NAD(P)H-sensing domain was mapped to residues 1–61 within the bHLH domain, demonstrating that redox sensing and heme-based gas sensing operate through distinct structural elements of NPAS2.\",\n      \"evidence\": \"EMSA with systematic truncation mutants of the NPAS2 bHLH domain\",\n      \"pmids\": [\"23831463\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The molecular identity of the NAD(P)H-binding site within residues 1–61 was not determined\", \"Whether this redox sensing operates independently of heme in vivo was not tested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"NPAS2 was shown to be selectively expressed in D1R-positive medium spiny neurons of the nucleus accumbens, where it directly activates Drd3 transcription and regulates cocaine reward; this established NPAS2 as a cell-type-specific circadian regulator of dopaminergic signaling in the reward circuit.\",\n      \"evidence\": \"AAV-shRNA knockdown in NAc, ChIP-seq identifying Drd3 as direct target, cell sorting qRT-PCR, conditioned place preference\",\n      \"pmids\": [\"25444159\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether NPAS2 regulation of Drd3 involves BMAL1 co-binding at the Drd3 E-box was not shown\", \"The full NPAS2 targetome in D1R-MSNs was not defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"NPAS2 was demonstrated to sustain autonomous circadian rhythms in peripheral cells (fibroblasts) in the absence of CLOCK, resolving the longstanding question of whether NPAS2's redundancy with CLOCK extends beyond the forebrain to peripheral oscillators.\",\n      \"evidence\": \"Single-cell PER2::LUC bioluminescence imaging in CLOCK-deficient fibroblasts with Npas2 siRNA knockdown\",\n      \"pmids\": [\"26895328\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether NPAS2 drives identical or distinct target gene repertoires compared to CLOCK in peripheral tissues was not resolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"NPAS2 was linked to cell proliferation and tumor biology through direct transcriptional activation of CDC25A (promoting cell cycle progression) and to anxiety-related behavior through transcriptional regulation of GABA-A receptor subunit genes in the ventral striatum.\",\n      \"evidence\": \"ChIP, Co-IP, reporter assays, and xenograft models for CDC25A in hepatocellular carcinoma; KO and striatal knockdown with behavioral testing for GABA-A targets\",\n      \"pmids\": [\"28333141\", \"29163035\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether CDC25A regulation by NPAS2 is circadian or constitutive was not determined\", \"The specific E-box elements in Gabra genes bound by NPAS2 were not mapped\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Cell-type-specific manipulation demonstrated that NPAS2 in D1R-MSNs (but not D2R-MSNs) controls excitatory synaptic strength and cocaine-induced synaptic potentiation, while tissue-specific studies identified HES1 and HIF-1α as direct NPAS2 targets linking the circadian clock to Notch signaling, fibrogenesis, and metabolic reprogramming.\",\n      \"evidence\": \"Cre-inducible cell-type-specific shRNA with electrophysiology in D1R vs. D2R MSNs; ChIP and reporter assays for HES1 in hepatic stellate cells and HIF-1α in hepatocellular carcinoma cells with in vivo models\",\n      \"pmids\": [\"30962277\", \"31778954\", \"31765736\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How NPAS2 loss increases excitatory drive in D1R-MSNs at the transcriptional target level was not fully elucidated\", \"Whether HIF-1α activation by NPAS2 is E-box-dependent or involves an indirect mechanism was not definitively shown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"NPAS2 was found to physically interact with SIRT1 in the nucleus accumbens, sharing transcriptional targets in reward and metabolic pathways, and to directly activate hepatic CYP1A2 transcription via an E-box-like element, extending the NPAS2 target repertoire to drug metabolism and NAD+-dependent epigenetic regulation.\",\n      \"evidence\": \"Co-IP and ChIP-seq cross-analysis with behavioral epistasis for SIRT1 interaction; Npas2-KO mice with ChIP-seq, reporter assays, and pharmacokinetic studies for CYP1A2\",\n      \"pmids\": [\"35001440\", \"36379250\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether SIRT1 deacetylates NPAS2 or BMAL1 in the NPAS2:BMAL1 complex specifically was not tested\", \"The full hepatic NPAS2 cistrome remains incompletely defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Post-transcriptional regulation of Npas2 mRNA by m6A modification was identified: FTO-mediated demethylation destabilizes Npas2 mRNA via PRRC2A, and loss of this suppression elevates NPAS2 to activate HIF-1α-driven glycolysis in macrophages, linking epitranscriptomic regulation of NPAS2 to innate immune metabolic reprogramming.\",\n      \"evidence\": \"MeRIP-seq, loss/gain-of-function of FTO and NPAS2 in bone marrow-derived macrophages, db/db mouse diabetic nephropathy model\",\n      \"pmids\": [\"39831513\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether m6A regulation of Npas2 mRNA occurs in other cell types or is macrophage-specific was not addressed\", \"The specific m6A sites on Npas2 mRNA were not individually validated by site-directed mutagenesis\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"NPAS2 in medial prefrontal cortex was shown to orchestrate afternoon nap behavior by transcriptionally activating POU2F2, which represses tyrosine hydroxylase to suppress dopamine synthesis in TH+ mPFC neurons, establishing a circadian transcriptional cascade governing daytime sleep architecture.\",\n      \"evidence\": \"ChIP and reporter assays defining NPAS2→POU2F2→TH pathway, region-specific viral NPAS2 manipulation with in vivo nap monitoring and TH+ neuron electrophysiology\",\n      \"pmids\": [\"41839866\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the NPAS2→POU2F2→TH axis operates in other dopaminergic brain regions is unknown\", \"The contribution of BMAL1 to this mPFC-specific function was not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: (1) the crystal or cryo-EM structure of heme-bound NPAS2, alone and in complex with BMAL1 on DNA; (2) the molecular mechanism by which NAD(P)H enhances DNA binding through the bHLH domain; (3) how NPAS2 and CLOCK achieve tissue-specific or target-specific selectivity despite apparent redundancy; and (4) whether the diverse non-circadian functions of NPAS2 (cell cycle, fibrosis, metabolic reprogramming) operate through canonical E-box-dependent BMAL1 heterodimerization or through distinct mechanisms.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of any NPAS2 domain in complex with BMAL1\", \"NAD(P)H-binding site within bHLH residues 1–61 is structurally undefined\", \"Tissue-specific NPAS2 vs. CLOCK cistrome comparison is lacking\", \"Whether NPAS2 can function independently of BMAL1 in any context is untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [1, 11, 19, 21, 24, 29, 32]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0, 2, 9, 13, 15]},\n      {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [0, 2, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1, 6, 13, 19]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9909396\", \"supporting_discovery_ids\": [1, 4, 7, 11, 12, 13, 14, 16, 29]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 1, 9, 19, 21, 24, 29, 32]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [3, 19, 22, 25, 32]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [5, 23, 26]}\n    ],\n    \"complexes\": [\n      \"NPAS2:BMAL1 heterodimer\"\n    ],\n    \"partners\": [\n      \"BMAL1\",\n      \"CRY1\",\n      \"CRY2\",\n      \"SIRT1\",\n      \"RARA\",\n      \"RXRA\",\n      \"ARNTL2\",\n      \"PER2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}