{"gene":"OPN3","run_date":"2026-04-29T11:37:57","timeline":{"discoveries":[{"year":1999,"finding":"OPN3 (encephalopsin) was identified as the first putative extraocular opsin in mammals, with strong and specific expression in discrete brain regions including the preoptic area, paraventricular nucleus of the hypothalamus, cerebral cortex, cerebellar Purkinje cells, striatal neurons, and spinal cord interneurons, suggesting a role in encephalic photoreception.","method":"In situ hybridization and Northern blot localization in mouse brain","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — foundational discovery paper with detailed regional expression mapping, highly cited (186 citations), replicated in subsequent studies","pmids":["10234000"],"is_preprint":false},{"year":2013,"finding":"Opn3 homologs (pufferfish PufTMT and mosquito MosOpn3) form functional photopigments by binding 11-cis and 9-cis retinals, with absorption maxima in the blue-to-green region, exhibit bistable photochemistry, and activate Gi-type and Go-type G proteins in a light-dependent manner, indicating Opn3 can function as a light-sensitive Gi/Go-coupled receptor.","method":"Heterologous expression in cultured cells, spectroscopic absorption measurement, cAMP/G protein activation assays, retinal-dependent photosensitivity assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — reconstitution of photopigment in vitro with spectroscopic validation and functional G protein coupling assays, highly cited (125 citations)","pmids":["23479626"],"is_preprint":false},{"year":2016,"finding":"Vertebrate Opn3 (zebrafish, pufferfish, anole, chicken) forms a blue-sensitive photopigment with absorption maximum ~465 nm when incubated with 11-cis retinal, and chimeric Opn3 constructs (with the third intracellular loop replaced by that of a Gs-coupled jellyfish opsin) activate G protein signaling in a light- and wavelength-dependent manner, demonstrating that Opn3 is capable of light-dependent G protein activation.","method":"Heterologous expression, spectroscopic absorption measurement, cAMP-dependent luciferase reporter assay with chimeric opsins, site-directed mutagenesis of intracellular loop","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1 — spectroscopic characterization plus functional reporter assay with chimera/mutagenesis across multiple vertebrate species","pmids":["27532629"],"is_preprint":false},{"year":2012,"finding":"OPN3 (encephalopsin) protein is present in neurons of the mouse cerebral cortex, paraventricular area, and cerebellar cells, but not in peripheral tissues, establishing its protein-level expression pattern in the brain.","method":"Western blotting and immunohistochemistry with antibody specificity controls (peptide blocking, primary antibody omission)","journal":"Journal of comparative physiology. A","confidence":"Medium","confidence_rationale":"Tier 2 — direct protein localization with specificity controls, moderate citation count","pmids":["22991144"],"is_preprint":false},{"year":2019,"finding":"In chick Müller glial cells (MCs), blue light exposure significantly increased OPN3 protein levels and modified its nuclear localization through a mechanism dependent on protein synthesis; additionally, a subpopulation of MCs responded to brief blue light pulses with increased intracellular Ca2+ levels, and this response was abolished by hydroxylamine (retinal bleacher) pretreatment, implicating retinal-dependent OPN3 activity in photic Ca2+ signaling in glia.","method":"Immunofluorescence localization, Ca2+ imaging with pharmacological inhibition (hydroxylamine), western blotting","journal":"Frontiers in cellular neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 — direct subcellular localization tied to functional Ca2+ response with pharmacological validation","pmids":["31474836"],"is_preprint":false},{"year":2021,"finding":"OPN3 protein is specifically expressed in tooth germ cells from bud to bell stages and surrounding tissues during mouse embryogenesis, and missense mutations in OPN3 (p.Gly223Asp, p.Met256Ile) co-segregate with non-syndromic oligodontia, implicating OPN3 in tooth development.","method":"Immunohistochemistry in mouse embryo, whole exome sequencing and Sanger validation in human families","journal":"Journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 — direct protein localization combined with human genetic evidence for loss-of-function phenotype","pmids":["33611338"],"is_preprint":false},{"year":2022,"finding":"OPN3 acts as a negative regulator of melanin production in BRAFV600E congenital melanocytic nevus (CMN) cells by modulating BRAFV600E/ERK signaling; OPN3 knockdown inhibits the BRAFV600E/ERK pathway and upregulates tyrosinase, TRP1, and TRP2, increasing melanin levels; furthermore, OPN3 and BRAFV600E form a physical protein complex.","method":"siRNA knockdown, overexpression, co-immunoprecipitation (physical complex), western blotting, 3D nevus model","journal":"The Journal of investigative dermatology","confidence":"Medium","confidence_rationale":"Tier 2/3 — Co-IP demonstrating physical complex plus functional KD with defined melanogenesis phenotype in a single lab","pmids":["35577105"],"is_preprint":false},{"year":2022,"finding":"The p.I51T missense variant of OPN3 fails to effectively dock with 11-cis-retinal (by molecular docking) and fails to induce detectable changes in intracellular Ca2+ concentration in vitro, demonstrating that this residue is critical for OPN3's canonical retinal-binding and light-sensing function.","method":"Molecular docking simulation, site-directed mutagenesis, in vitro fluorescence calcium imaging","journal":"Experimental dermatology","confidence":"Medium","confidence_rationale":"Tier 1/3 — site-directed mutagenesis with functional Ca2+ assay plus computational docking, single lab","pmids":["36017595"],"is_preprint":false},{"year":2023,"finding":"OPN3 germline knockout mice exhibit a refractive myopia phenotype with decreased lens thickness, shallower aqueous compartment depth, and shorter axial length; retina-conditional Opn3 knockout does not replicate this phenotype, indicating that an OPN3 expression domain outside the retina (with OPN3 expressed in a subset of retinal ganglion cells and choroidal cells) controls lens shape and refractive performance. The Opn3 null retinal gene expression signature after myopia induction shows opposing polarity of Ctgf, Cx43, and Egr1 compared to controls.","method":"Opn3-eGFP reporter, infrared photorefractor, SD-OCT biometry, lens-induced myopia with skull-mounted goggles, retinal conditional knockout, gene expression analysis","journal":"Molecular vision","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis via conditional vs. germline KO with multiple quantitative ocular phenotype readouts establishes extra-retinal OPN3 as the relevant domain","pmids":["37287644"],"is_preprint":false},{"year":2022,"finding":"Opn3-deficient mice have a selectively attenuated acoustic startle reflex (ASR) relative to wild-type littermates, with no change in hearing sensitivity, establishing a role for Opn3 in modulating brainstem sensorimotor gating; Opn3 was shown by reporter expression to be present in cochlear outer hair cells and auditory/vestibular structures.","method":"Comprehensive behavioral battery in Opn3 knockout mice, acoustic startle reflex testing, auditory brainstem response, Opn3-eGFP reporter localization","journal":"eNeuro","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO with specific behavioral phenotype and localization data, single lab","pmids":["36041828"],"is_preprint":false},{"year":2024,"finding":"Blue light activates TRPV1 downstream of OPN3 in melanocytes, inducing calcium influx that activates CaMKII and MAPK signaling, downregulates clusterin, promotes nuclear translocation of PAX3, and ultimately stimulates melanin synthesis; simultaneously, OPN3-TRPV1-calcium signaling inhibits autophagy-mediated melanosome degradation by decreasing clusterin-LC3B interaction and reducing ATF family expression.","method":"siRNA knockdown, calcium imaging, western blotting, reporter assays for pathway components, co-immunoprecipitation (clusterin-LC3B interaction)","journal":"The Journal of investigative dermatology","confidence":"Medium","confidence_rationale":"Tier 2/3 — multiple downstream pathway components tested with KD and signaling assays, single lab, defines OPN3-TRPV1-Ca2+ signaling axis","pmids":["39241981"],"is_preprint":false},{"year":2024,"finding":"Blue light exposure causes dissociation of 11-cis-retinal from OPN3 and accumulation of all-trans retinal in thyroid cancer cells, disrupting proliferation pathways and inducing G0/G1 cell cycle arrest through the Retinal-OPN3 complex.","method":"Blue light exposure of PTC cells, cell cycle analysis, western blotting for proliferation pathway proteins, retinal isomer measurements","journal":"Cell communication and signaling","confidence":"Low","confidence_rationale":"Tier 3 — single lab, limited mechanistic detail, no direct mutagenesis or reconstitution of the retinal-OPN3 complex","pmids":["39487504"],"is_preprint":false},{"year":2025,"finding":"OPN3 regulates angiogenesis in human umbilical vein endothelial cells (HUVECs) through physical interaction with VEGFR2; OPN3 and VEGFR2 co-localize at the plasma membrane and form a physical complex, and OPN3 promotes HUVEC proliferation, migration, sprouting, and tube formation via the VEGFR2-AKT signaling pathway; OPN3 knockdown or knockout in zebrafish impairs embryonic angiogenesis and vascular development.","method":"siRNA knockdown, CRISPR knockout in zebrafish, co-immunoprecipitation, co-localization imaging, tube formation and sprouting assays, AKT pathway western blotting","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 — reciprocal Co-IP for physical complex, in vivo zebrafish KO phenotype, and in vitro functional assays converge on VEGFR2-AKT pathway","pmids":["40164822"],"is_preprint":false},{"year":2025,"finding":"Opn3 knockout mice exhibit a larger decrease in body temperature under cold exposure and a refractive myopia phenotype, confirming functional knockout; phiC31 integrase-mediated recombination driven by the Opn3 promoter achieves 30-44% efficiency in cerebellum, mapping Opn3-expressing cells mainly to olfactory bulb, cerebral cortex, thalamus, and cerebellum.","method":"CRISPR-Cas9 knock-in of phiC31o, in situ hybridization, telemetric body temperature monitoring, infrared photorefractor for refractive phenotype, fluorescent reporter lineage tracing","journal":"Eye and vision","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO confirmed by multiple phenotypic readouts (thermoregulation, refraction) with direct cell-type labeling","pmids":["41102823"],"is_preprint":false},{"year":2026,"finding":"In hepatocytes, blue light acts through Opn3 to reduce lipid droplet accumulation by activating the Pparα signaling pathway and promoting p62-mediated autophagy; Opn3 knockout abolishes blue-light-induced lipid droplet degradation, nuclear Pparα accumulation, and autophagic effects. Additionally, blue light via Opn3 suppresses replication of VSV, H1N1, and EMCV viruses and alleviates virus-induced cell death and inflammatory responses.","method":"Opn3 knockout cells, blue light irradiation (470-480 nm), lipid droplet quantification, triglyceride/cholesterol measurement, Pparα nuclear translocation imaging, autophagy (p62) western blotting, viral replication assays","journal":"Biomolecules","confidence":"Medium","confidence_rationale":"Tier 2 — KO with multiple orthogonal readouts (lipid, autophagy, antiviral) in single study, novel pathway defined (Opn3-Pparα/p62 axis)","pmids":["41594649"],"is_preprint":false}],"current_model":"OPN3 (encephalopsin) is a non-visual, blue-light-sensitive G protein-coupled receptor that binds 11-cis retinal to form a bistable photopigment capable of activating Gi/Go-type G proteins; in extraocular tissues it mediates light-dependent signaling (Ca2+ influx via TRPV1, cAMP modulation, Pparα/p62-autophagy axis) as well as light-independent functions including physical interaction with BRAFV600E to regulate melanogenesis, interaction with VEGFR2 to promote angiogenesis via AKT, and roles in ocular emmetropization, auditory startle modulation, tooth development, and thermoregulation."},"narrative":{"teleology":[{"year":1999,"claim":"The discovery of OPN3 as the first mammalian extraocular opsin established that photoreceptive GPCRs exist in the brain, raising the question of whether OPN3 is a functional photopigment or an orphan receptor.","evidence":"In situ hybridization and Northern blot mapping of OPN3 mRNA in discrete mouse brain regions","pmids":["10234000"],"confidence":"High","gaps":["No demonstration that OPN3 binds retinal or absorbs light","No functional signaling activity measured","Peripheral tissue expression not systematically surveyed"]},{"year":2013,"claim":"Reconstitution of OPN3 homologs as bistable, retinal-binding photopigments with Gi/Go coupling resolved the fundamental question of whether OPN3 is a bona fide light sensor, establishing its blue-to-green spectral sensitivity and G protein specificity.","evidence":"Heterologous expression with spectroscopic absorption measurement and cAMP/G protein activation assays for pufferfish and mosquito OPN3","pmids":["23479626"],"confidence":"High","gaps":["Mammalian OPN3 itself was not directly reconstituted in this study","Downstream signaling pathways in native tissues unknown","Whether OPN3 has light-independent functions not addressed"]},{"year":2016,"claim":"Characterization of vertebrate OPN3 orthologs confirmed a conserved ~465 nm blue-light absorption maximum and light-dependent G protein activation across species, solidifying OPN3 as a blue-light photopigment.","evidence":"Spectroscopy and chimeric opsin cAMP reporter assays with zebrafish, pufferfish, anole, and chicken OPN3","pmids":["27532629"],"confidence":"High","gaps":["Endogenous signaling partners and downstream effectors in mammalian cells unresolved","In vivo physiological consequence of OPN3 photosensing not demonstrated"]},{"year":2019,"claim":"Demonstration that blue light triggers retinal-dependent Ca²⁺ transients in chick Müller glia via OPN3 provided the first link between OPN3 photosensing and intracellular calcium signaling in a native cell type.","evidence":"Ca²⁺ imaging with hydroxylamine-mediated retinal bleaching and OPN3 immunolocalization in Müller cells","pmids":["31474836"],"confidence":"Medium","gaps":["Specific G protein and channel mediating Ca²⁺ entry not identified","OPN3 knockdown/knockout not performed to confirm specificity","Whether this pathway operates in mammalian glia unknown"]},{"year":2021,"claim":"Human genetic evidence linked OPN3 missense mutations to non-syndromic oligodontia and OPN3 protein was localized to tooth germ cells during embryogenesis, establishing an unexpected developmental role.","evidence":"Whole exome sequencing in oligodontia families with immunohistochemistry in mouse embryos","pmids":["33611338"],"confidence":"Medium","gaps":["No functional rescue or animal model confirming causality of the missense variants","Downstream signaling pathway in tooth development unknown","Light-dependent vs. light-independent mechanism not distinguished"]},{"year":2022,"claim":"Multiple in vivo knockout studies revealed that OPN3 loss causes attenuated acoustic startle reflex and refractive myopia (from extra-retinal domains), demonstrating broad non-visual physiological roles and establishing that OPN3 functions outside classical photoreceptor cells.","evidence":"Opn3 germline vs. retina-conditional KO mice with acoustic startle testing, infrared photorefractor, and SD-OCT biometry","pmids":["36041828","37287644"],"confidence":"High","gaps":["The cell type mediating extra-retinal myopia control not definitively identified","Mechanism linking OPN3 to startle circuit modulation unknown","Whether these phenotypes are light-dependent in vivo not tested"]},{"year":2022,"claim":"OPN3 was shown to physically interact with BRAFV600E to modulate ERK signaling and melanogenesis in a light-independent manner, revealing a non-canonical function as a signaling scaffold in melanocytic cells.","evidence":"Co-immunoprecipitation, siRNA knockdown, and overexpression in BRAFV600E congenital melanocytic nevus cells and 3D nevus models","pmids":["35577105"],"confidence":"Medium","gaps":["Co-IP performed in a single lab; reciprocal validation and domain mapping not shown","Whether the OPN3-BRAF interaction requires retinal not determined","Relevance to non-mutant BRAF signaling not established"]},{"year":2024,"claim":"A detailed OPN3-TRPV1-Ca²⁺-CaMKII signaling axis was delineated in melanocytes, connecting blue-light photosensing to dual outputs: PAX3-driven melanin synthesis and clusterin-LC3B-mediated inhibition of melanosome autophagy.","evidence":"siRNA knockdown, calcium imaging, western blotting, and co-immunoprecipitation of clusterin-LC3B in melanocytes","pmids":["39241981"],"confidence":"Medium","gaps":["Direct physical interaction between OPN3 and TRPV1 not demonstrated","Single-lab study; independent replication needed","Whether the autophagy branch operates in non-melanocytic cells unknown"]},{"year":2025,"claim":"OPN3 was found to physically complex with VEGFR2 at the plasma membrane and promote angiogenesis via the VEGFR2-AKT pathway, extending OPN3's non-canonical roles to vascular biology and confirmed by zebrafish knockout vascular phenotypes.","evidence":"Reciprocal co-immunoprecipitation, co-localization imaging, tube formation and sprouting assays in HUVECs, CRISPR knockout in zebrafish","pmids":["40164822"],"confidence":"Medium","gaps":["Whether OPN3-VEGFR2 interaction is light-dependent or light-independent not resolved","Structural basis of the OPN3-VEGFR2 complex unknown","In vivo relevance in mammalian vasculature not tested"]},{"year":2025,"claim":"Opn3 knockout confirmed thermoregulatory deficits under cold stress and refractive myopia, and lineage tracing mapped Opn3-expressing cells primarily to olfactory bulb, cerebral cortex, thalamus, and cerebellum, refining the anatomical basis for OPN3's neural phenotypes.","evidence":"CRISPR knock-in of phiC31o reporter, telemetric body temperature monitoring, infrared photorefractor in KO mice","pmids":["41102823"],"confidence":"Medium","gaps":["Mechanism linking OPN3 to thermoregulation not defined","Recombination efficiency in some brain regions was modest (30–44%)","Whether thermoregulation phenotype is light-dependent not tested"]},{"year":2026,"claim":"A PPARα/p62-autophagy axis was defined as the mechanism by which OPN3 mediates blue-light-induced lipid droplet clearance in hepatocytes, expanding OPN3's physiological scope to lipid metabolism and antiviral defense.","evidence":"Opn3 KO hepatocytes, blue light irradiation with lipid droplet quantification, PPARα nuclear translocation imaging, p62 western blotting, viral replication assays","pmids":["41594649"],"confidence":"Medium","gaps":["G protein coupling in hepatocytes not characterized","Whether hepatic retinal availability is sufficient for OPN3 function in vivo unknown","Antiviral mechanism downstream of OPN3 not molecularly defined"]},{"year":null,"claim":"Key unresolved questions include the structural basis of OPN3's dual capacity for light-dependent signaling and light-independent protein scaffolding, the identity of its direct G protein partners in native mammalian tissues, and whether its diverse physiological roles (thermoregulation, startle modulation, tooth development) operate through retinal-dependent or retinal-independent mechanisms.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of OPN3 or its complexes with BRAFV600E or VEGFR2","Mammalian OPN3 has not been directly reconstituted as a photopigment (only homologs)","Light-dependence vs. light-independence of in vivo phenotypes not systematically tested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[1,2]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[6,12]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[6,12]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[12]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,6,10,12]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[10,14]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[14]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[5,8]},{"term_id":"R-HSA-9709957","term_label":"Sensory Perception","supporting_discovery_ids":[1,9]}],"complexes":[],"partners":["BRAF","VEGFR2","TRPV1"],"other_free_text":[]},"mechanistic_narrative":"OPN3 (encephalopsin) is a non-visual, bistable opsin that functions as a blue-light-sensitive G protein-coupled receptor in diverse extraocular tissues, coupling retinal photoisomerization to Gi/Go-type G protein activation and downstream calcium, cAMP, and MAPK signaling [PMID:23479626, PMID:27532629, PMID:39241981]. Beyond canonical light-dependent signaling—where it binds 11-cis retinal (~465 nm absorption maximum) and triggers TRPV1-mediated Ca²⁺ influx to regulate melanogenesis and autophagy [PMID:39241981, PMID:41594649]—OPN3 also engages in light-independent protein–protein interactions, physically complexing with BRAFV600E to modulate ERK-driven melanin production and with VEGFR2 to promote AKT-dependent angiogenesis [PMID:35577105, PMID:40164822]. Germline Opn3 knockout in mice produces refractive myopia with altered lens biometry (originating from an extra-retinal expression domain), attenuated acoustic startle reflex, and impaired cold-stress thermoregulation, while human OPN3 missense mutations co-segregate with non-syndromic oligodontia [PMID:37287644, PMID:36041828, PMID:41102823, PMID:33611338]. In hepatocytes, OPN3 mediates blue-light-induced lipid droplet clearance through a PPARα/p62-autophagy axis and suppresses viral replication [PMID:41594649]."},"prefetch_data":{"uniprot":{"accession":"Q9H1Y3","full_name":"Opsin-3","aliases":["Encephalopsin","Panopsin"],"length_aa":402,"mass_kda":44.9,"function":"G protein-coupled receptor which selectively activates G(i/o) proteins via ultraviolet A (UVA) light-mediated activation in the skin, thereby decreasing cellular cAMP (PubMed:28842328, PubMed:31380578). Binds both 11-cis retinal and all-trans retinal (PubMed:31097585). Regulates melanogenesis in melanocytes by specifically inhibiting MC1R-evoked cAMP signaling, modulating calcium flux, regulating CAMK2 phosphorylation, and subsequently phosphorylating CREB, p38, ERK and MITF, probably in a constitutive, light-independent manner (PubMed:28842328, PubMed:31097585). In the paraventricular nucleus of the hypothalamus, inhibits MC4R-mediated cAMP signaling and activates KCNJ13 channel opening in a constitutive manner, thereby promoting food intake and modulating spontaneous firing of neurons (PubMed:39951488). Plays a role in melanocyte survival through regulation of intracellular calcium levels and subsequent BCL2/RAF1 signaling (PubMed:31730232). Additionally regulates apoptosis via cytochrome c release and subsequent activation of the caspase cascade (PubMed:31730232). Required for TYR and DCT blue light-induced complex formation in melanocytes (PubMed:28842328). Involved in keratinocyte differentiation in response to blue-light (PubMed:30168605). Required for the UVA-mediated induction of calcium and mitogen-activated protein kinase signaling resulting in the expression of MMP1, MMP2, MMP3, MMP9 and TIMP1 in dermal fibroblasts (PubMed:31380578). Plays a role in light-mediated glucose uptake, mitochondrial respiration and fatty acid metabolism in brown adipocyte tissues (By similarity). May be involved in photorelaxation of airway smooth muscle cells, via blue-light dependent GPCR signaling pathways (By similarity)","subcellular_location":"Cell membrane; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q9H1Y3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/OPN3","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/OPN3","total_profiled":1310},"omim":[{"mim_id":"612433","title":"DEAFNESS, AUTOSOMAL RECESSIVE 45; DFNB45","url":"https://www.omim.org/entry/612433"},{"mim_id":"606695","title":"OPSIN 3; OPN3","url":"https://www.omim.org/entry/606695"},{"mim_id":"603538","title":"KYNURENINE 3-MONOOXYGENASE; KMO","url":"https://www.omim.org/entry/603538"},{"mim_id":"118825","title":"CHM-LIKE; CHML","url":"https://www.omim.org/entry/118825"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Cytosol","reliability":"Approved"},{"location":"Plasma membrane","reliability":"Additional"},{"location":"Primary cilium","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"placenta","ntpm":17.6}],"url":"https://www.proteinatlas.org/search/OPN3"},"hgnc":{"alias_symbol":["ERO","NMO-1","encephalopsin","PPP1R116"],"prev_symbol":["ECPN"]},"alphafold":{"accession":"Q9H1Y3","domains":[{"cath_id":"1.20.1070.10","chopping":"39-327","consensus_level":"high","plddt":95.8077,"start":39,"end":327}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H1Y3","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H1Y3-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H1Y3-F1-predicted_aligned_error_v6.png","plddt_mean":79.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=OPN3","jax_strain_url":"https://www.jax.org/strain/search?query=OPN3"},"sequence":{"accession":"Q9H1Y3","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9H1Y3.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9H1Y3/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H1Y3"}},"corpus_meta":[{"pmid":"10234000","id":"PMC_10234000","title":"Encephalopsin: a novel mammalian extraretinal opsin discretely localized in the brain.","date":"1999","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/10234000","citation_count":186,"is_preprint":false},{"pmid":"23479626","id":"PMC_23479626","title":"Homologs of vertebrate Opn3 potentially serve as a light sensor in nonphotoreceptive tissue.","date":"2013","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/23479626","citation_count":125,"is_preprint":false},{"pmid":"27532629","id":"PMC_27532629","title":"Absorption Characteristics of Vertebrate Non-Visual Opsin, Opn3.","date":"2016","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/27532629","citation_count":65,"is_preprint":false},{"pmid":"22991144","id":"PMC_22991144","title":"Encephalopsin (OPN3) protein abundance in the adult mouse brain.","date":"2012","source":"Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology","url":"https://pubmed.ncbi.nlm.nih.gov/22991144","citation_count":42,"is_preprint":false},{"pmid":"31474836","id":"PMC_31474836","title":"Expression of Non-visual Opsins Opn3 and Opn5 in the Developing Inner Retinal Cells of Birds. Light-Responses in Müller Glial Cells.","date":"2019","source":"Frontiers in cellular neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/31474836","citation_count":27,"is_preprint":false},{"pmid":"31802643","id":"PMC_31802643","title":"Expression of OPN3 in lung adenocarcinoma promotes epithelial-mesenchymal transition and tumor metastasis.","date":"2019","source":"Thoracic cancer","url":"https://pubmed.ncbi.nlm.nih.gov/31802643","citation_count":22,"is_preprint":false},{"pmid":"34417283","id":"PMC_34417283","title":"Distinct Opsin 3 (Opn3) Expression in the Developing Nervous System during Mammalian Embryogenesis.","date":"2021","source":"eNeuro","url":"https://pubmed.ncbi.nlm.nih.gov/34417283","citation_count":19,"is_preprint":false},{"pmid":"37287644","id":"PMC_37287644","title":"Encephalopsin (OPN3) is required for normal refractive development and the GO/GROW response to induced myopia.","date":"2023","source":"Molecular vision","url":"https://pubmed.ncbi.nlm.nih.gov/37287644","citation_count":17,"is_preprint":false},{"pmid":"12242008","id":"PMC_12242008","title":"Different structural organization of the encephalopsin gene in man and mouse.","date":"2002","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/12242008","citation_count":17,"is_preprint":false},{"pmid":"20067495","id":"PMC_20067495","title":"Spatiotemporal expression pattern of an encephalopsin orthologue of the sea urchin Hemicentrotus pulcherrimus during early development, and its potential role in larval vertical migration.","date":"2010","source":"Development, growth & differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/20067495","citation_count":17,"is_preprint":false},{"pmid":"38692092","id":"PMC_38692092","title":"Non-esterified fatty acid palmitate facilitates oxidative endoplasmic reticulum stress and apoptosis of β-cells by upregulating ERO-1α expression.","date":"2024","source":"Redox biology","url":"https://pubmed.ncbi.nlm.nih.gov/38692092","citation_count":15,"is_preprint":false},{"pmid":"29379995","id":"PMC_29379995","title":"Evidence for encephalopsin immunoreactivity in interneurones and striosomes of the monkey striatum.","date":"2018","source":"Experimental brain research","url":"https://pubmed.ncbi.nlm.nih.gov/29379995","citation_count":14,"is_preprint":false},{"pmid":"25805701","id":"PMC_25805701","title":"Transcranial light affects plasma monoamine levels and expression of brain encephalopsin in the mouse.","date":"2015","source":"The Journal of experimental biology","url":"https://pubmed.ncbi.nlm.nih.gov/25805701","citation_count":14,"is_preprint":false},{"pmid":"39241981","id":"PMC_39241981","title":"The Pigmentation of Blue Light Is Mediated by Both Melanogenesis Activation and Autophagy Inhibition through OPN3-TRPV1.","date":"2024","source":"The Journal of investigative dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/39241981","citation_count":13,"is_preprint":false},{"pmid":"36041828","id":"PMC_36041828","title":"Comprehensive Behavioral Analysis of Opsin 3 (Encephalopsin)-Deficient Mice Identifies Role in Modulation of Acoustic Startle Reflex.","date":"2022","source":"eNeuro","url":"https://pubmed.ncbi.nlm.nih.gov/36041828","citation_count":9,"is_preprint":false},{"pmid":"33611338","id":"PMC_33611338","title":"Identification of OPN3 as associated with non-syndromic oligodontia in a Japanese population.","date":"2021","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/33611338","citation_count":6,"is_preprint":false},{"pmid":"39487504","id":"PMC_39487504","title":"Blue light-driven cell cycle arrest in thyroid cancer via Retinal-OPN3 complex.","date":"2024","source":"Cell communication and signaling : CCS","url":"https://pubmed.ncbi.nlm.nih.gov/39487504","citation_count":5,"is_preprint":false},{"pmid":"36058246","id":"PMC_36058246","title":"Expression of a homologue of a vertebrate non-visual opsin Opn3 in the insect photoreceptors.","date":"2022","source":"Philosophical transactions of the Royal Society of London. 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hybridization and Northern blot localization in mouse brain\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — foundational discovery paper with detailed regional expression mapping, highly cited (186 citations), replicated in subsequent studies\",\n      \"pmids\": [\"10234000\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Opn3 homologs (pufferfish PufTMT and mosquito MosOpn3) form functional photopigments by binding 11-cis and 9-cis retinals, with absorption maxima in the blue-to-green region, exhibit bistable photochemistry, and activate Gi-type and Go-type G proteins in a light-dependent manner, indicating Opn3 can function as a light-sensitive Gi/Go-coupled receptor.\",\n      \"method\": \"Heterologous expression in cultured cells, spectroscopic absorption measurement, cAMP/G protein activation assays, retinal-dependent photosensitivity assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution of photopigment in vitro with spectroscopic validation and functional G protein coupling assays, highly cited (125 citations)\",\n      \"pmids\": [\"23479626\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Vertebrate Opn3 (zebrafish, pufferfish, anole, chicken) forms a blue-sensitive photopigment with absorption maximum ~465 nm when incubated with 11-cis retinal, and chimeric Opn3 constructs (with the third intracellular loop replaced by that of a Gs-coupled jellyfish opsin) activate G protein signaling in a light- and wavelength-dependent manner, demonstrating that Opn3 is capable of light-dependent G protein activation.\",\n      \"method\": \"Heterologous expression, spectroscopic absorption measurement, cAMP-dependent luciferase reporter assay with chimeric opsins, site-directed mutagenesis of intracellular loop\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — spectroscopic characterization plus functional reporter assay with chimera/mutagenesis across multiple vertebrate species\",\n      \"pmids\": [\"27532629\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"OPN3 (encephalopsin) protein is present in neurons of the mouse cerebral cortex, paraventricular area, and cerebellar cells, but not in peripheral tissues, establishing its protein-level expression pattern in the brain.\",\n      \"method\": \"Western blotting and immunohistochemistry with antibody specificity controls (peptide blocking, primary antibody omission)\",\n      \"journal\": \"Journal of comparative physiology. A\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct protein localization with specificity controls, moderate citation count\",\n      \"pmids\": [\"22991144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In chick Müller glial cells (MCs), blue light exposure significantly increased OPN3 protein levels and modified its nuclear localization through a mechanism dependent on protein synthesis; additionally, a subpopulation of MCs responded to brief blue light pulses with increased intracellular Ca2+ levels, and this response was abolished by hydroxylamine (retinal bleacher) pretreatment, implicating retinal-dependent OPN3 activity in photic Ca2+ signaling in glia.\",\n      \"method\": \"Immunofluorescence localization, Ca2+ imaging with pharmacological inhibition (hydroxylamine), western blotting\",\n      \"journal\": \"Frontiers in cellular neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct subcellular localization tied to functional Ca2+ response with pharmacological validation\",\n      \"pmids\": [\"31474836\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"OPN3 protein is specifically expressed in tooth germ cells from bud to bell stages and surrounding tissues during mouse embryogenesis, and missense mutations in OPN3 (p.Gly223Asp, p.Met256Ile) co-segregate with non-syndromic oligodontia, implicating OPN3 in tooth development.\",\n      \"method\": \"Immunohistochemistry in mouse embryo, whole exome sequencing and Sanger validation in human families\",\n      \"journal\": \"Journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct protein localization combined with human genetic evidence for loss-of-function phenotype\",\n      \"pmids\": [\"33611338\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"OPN3 acts as a negative regulator of melanin production in BRAFV600E congenital melanocytic nevus (CMN) cells by modulating BRAFV600E/ERK signaling; OPN3 knockdown inhibits the BRAFV600E/ERK pathway and upregulates tyrosinase, TRP1, and TRP2, increasing melanin levels; furthermore, OPN3 and BRAFV600E form a physical protein complex.\",\n      \"method\": \"siRNA knockdown, overexpression, co-immunoprecipitation (physical complex), western blotting, 3D nevus model\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — Co-IP demonstrating physical complex plus functional KD with defined melanogenesis phenotype in a single lab\",\n      \"pmids\": [\"35577105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The p.I51T missense variant of OPN3 fails to effectively dock with 11-cis-retinal (by molecular docking) and fails to induce detectable changes in intracellular Ca2+ concentration in vitro, demonstrating that this residue is critical for OPN3's canonical retinal-binding and light-sensing function.\",\n      \"method\": \"Molecular docking simulation, site-directed mutagenesis, in vitro fluorescence calcium imaging\",\n      \"journal\": \"Experimental dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1/3 — site-directed mutagenesis with functional Ca2+ assay plus computational docking, single lab\",\n      \"pmids\": [\"36017595\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"OPN3 germline knockout mice exhibit a refractive myopia phenotype with decreased lens thickness, shallower aqueous compartment depth, and shorter axial length; retina-conditional Opn3 knockout does not replicate this phenotype, indicating that an OPN3 expression domain outside the retina (with OPN3 expressed in a subset of retinal ganglion cells and choroidal cells) controls lens shape and refractive performance. The Opn3 null retinal gene expression signature after myopia induction shows opposing polarity of Ctgf, Cx43, and Egr1 compared to controls.\",\n      \"method\": \"Opn3-eGFP reporter, infrared photorefractor, SD-OCT biometry, lens-induced myopia with skull-mounted goggles, retinal conditional knockout, gene expression analysis\",\n      \"journal\": \"Molecular vision\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis via conditional vs. germline KO with multiple quantitative ocular phenotype readouts establishes extra-retinal OPN3 as the relevant domain\",\n      \"pmids\": [\"37287644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Opn3-deficient mice have a selectively attenuated acoustic startle reflex (ASR) relative to wild-type littermates, with no change in hearing sensitivity, establishing a role for Opn3 in modulating brainstem sensorimotor gating; Opn3 was shown by reporter expression to be present in cochlear outer hair cells and auditory/vestibular structures.\",\n      \"method\": \"Comprehensive behavioral battery in Opn3 knockout mice, acoustic startle reflex testing, auditory brainstem response, Opn3-eGFP reporter localization\",\n      \"journal\": \"eNeuro\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with specific behavioral phenotype and localization data, single lab\",\n      \"pmids\": [\"36041828\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Blue light activates TRPV1 downstream of OPN3 in melanocytes, inducing calcium influx that activates CaMKII and MAPK signaling, downregulates clusterin, promotes nuclear translocation of PAX3, and ultimately stimulates melanin synthesis; simultaneously, OPN3-TRPV1-calcium signaling inhibits autophagy-mediated melanosome degradation by decreasing clusterin-LC3B interaction and reducing ATF family expression.\",\n      \"method\": \"siRNA knockdown, calcium imaging, western blotting, reporter assays for pathway components, co-immunoprecipitation (clusterin-LC3B interaction)\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — multiple downstream pathway components tested with KD and signaling assays, single lab, defines OPN3-TRPV1-Ca2+ signaling axis\",\n      \"pmids\": [\"39241981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Blue light exposure causes dissociation of 11-cis-retinal from OPN3 and accumulation of all-trans retinal in thyroid cancer cells, disrupting proliferation pathways and inducing G0/G1 cell cycle arrest through the Retinal-OPN3 complex.\",\n      \"method\": \"Blue light exposure of PTC cells, cell cycle analysis, western blotting for proliferation pathway proteins, retinal isomer measurements\",\n      \"journal\": \"Cell communication and signaling\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single lab, limited mechanistic detail, no direct mutagenesis or reconstitution of the retinal-OPN3 complex\",\n      \"pmids\": [\"39487504\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"OPN3 regulates angiogenesis in human umbilical vein endothelial cells (HUVECs) through physical interaction with VEGFR2; OPN3 and VEGFR2 co-localize at the plasma membrane and form a physical complex, and OPN3 promotes HUVEC proliferation, migration, sprouting, and tube formation via the VEGFR2-AKT signaling pathway; OPN3 knockdown or knockout in zebrafish impairs embryonic angiogenesis and vascular development.\",\n      \"method\": \"siRNA knockdown, CRISPR knockout in zebrafish, co-immunoprecipitation, co-localization imaging, tube formation and sprouting assays, AKT pathway western blotting\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP for physical complex, in vivo zebrafish KO phenotype, and in vitro functional assays converge on VEGFR2-AKT pathway\",\n      \"pmids\": [\"40164822\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Opn3 knockout mice exhibit a larger decrease in body temperature under cold exposure and a refractive myopia phenotype, confirming functional knockout; phiC31 integrase-mediated recombination driven by the Opn3 promoter achieves 30-44% efficiency in cerebellum, mapping Opn3-expressing cells mainly to olfactory bulb, cerebral cortex, thalamus, and cerebellum.\",\n      \"method\": \"CRISPR-Cas9 knock-in of phiC31o, in situ hybridization, telemetric body temperature monitoring, infrared photorefractor for refractive phenotype, fluorescent reporter lineage tracing\",\n      \"journal\": \"Eye and vision\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO confirmed by multiple phenotypic readouts (thermoregulation, refraction) with direct cell-type labeling\",\n      \"pmids\": [\"41102823\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In hepatocytes, blue light acts through Opn3 to reduce lipid droplet accumulation by activating the Pparα signaling pathway and promoting p62-mediated autophagy; Opn3 knockout abolishes blue-light-induced lipid droplet degradation, nuclear Pparα accumulation, and autophagic effects. Additionally, blue light via Opn3 suppresses replication of VSV, H1N1, and EMCV viruses and alleviates virus-induced cell death and inflammatory responses.\",\n      \"method\": \"Opn3 knockout cells, blue light irradiation (470-480 nm), lipid droplet quantification, triglyceride/cholesterol measurement, Pparα nuclear translocation imaging, autophagy (p62) western blotting, viral replication assays\",\n      \"journal\": \"Biomolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO with multiple orthogonal readouts (lipid, autophagy, antiviral) in single study, novel pathway defined (Opn3-Pparα/p62 axis)\",\n      \"pmids\": [\"41594649\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"OPN3 (encephalopsin) is a non-visual, blue-light-sensitive G protein-coupled receptor that binds 11-cis retinal to form a bistable photopigment capable of activating Gi/Go-type G proteins; in extraocular tissues it mediates light-dependent signaling (Ca2+ influx via TRPV1, cAMP modulation, Pparα/p62-autophagy axis) as well as light-independent functions including physical interaction with BRAFV600E to regulate melanogenesis, interaction with VEGFR2 to promote angiogenesis via AKT, and roles in ocular emmetropization, auditory startle modulation, tooth development, and thermoregulation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"OPN3 (encephalopsin) is a non-visual, bistable opsin that functions as a blue-light-sensitive G protein-coupled receptor in diverse extraocular tissues, coupling retinal photoisomerization to Gi/Go-type G protein activation and downstream calcium, cAMP, and MAPK signaling [PMID:23479626, PMID:27532629, PMID:39241981]. Beyond canonical light-dependent signaling—where it binds 11-cis retinal (~465 nm absorption maximum) and triggers TRPV1-mediated Ca²⁺ influx to regulate melanogenesis and autophagy [PMID:39241981, PMID:41594649]—OPN3 also engages in light-independent protein–protein interactions, physically complexing with BRAFV600E to modulate ERK-driven melanin production and with VEGFR2 to promote AKT-dependent angiogenesis [PMID:35577105, PMID:40164822]. Germline Opn3 knockout in mice produces refractive myopia with altered lens biometry (originating from an extra-retinal expression domain), attenuated acoustic startle reflex, and impaired cold-stress thermoregulation, while human OPN3 missense mutations co-segregate with non-syndromic oligodontia [PMID:37287644, PMID:36041828, PMID:41102823, PMID:33611338]. In hepatocytes, OPN3 mediates blue-light-induced lipid droplet clearance through a PPARα/p62-autophagy axis and suppresses viral replication [PMID:41594649].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"The discovery of OPN3 as the first mammalian extraocular opsin established that photoreceptive GPCRs exist in the brain, raising the question of whether OPN3 is a functional photopigment or an orphan receptor.\",\n      \"evidence\": \"In situ hybridization and Northern blot mapping of OPN3 mRNA in discrete mouse brain regions\",\n      \"pmids\": [\"10234000\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No demonstration that OPN3 binds retinal or absorbs light\",\n        \"No functional signaling activity measured\",\n        \"Peripheral tissue expression not systematically surveyed\"\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Reconstitution of OPN3 homologs as bistable, retinal-binding photopigments with Gi/Go coupling resolved the fundamental question of whether OPN3 is a bona fide light sensor, establishing its blue-to-green spectral sensitivity and G protein specificity.\",\n      \"evidence\": \"Heterologous expression with spectroscopic absorption measurement and cAMP/G protein activation assays for pufferfish and mosquito OPN3\",\n      \"pmids\": [\"23479626\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mammalian OPN3 itself was not directly reconstituted in this study\",\n        \"Downstream signaling pathways in native tissues unknown\",\n        \"Whether OPN3 has light-independent functions not addressed\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Characterization of vertebrate OPN3 orthologs confirmed a conserved ~465 nm blue-light absorption maximum and light-dependent G protein activation across species, solidifying OPN3 as a blue-light photopigment.\",\n      \"evidence\": \"Spectroscopy and chimeric opsin cAMP reporter assays with zebrafish, pufferfish, anole, and chicken OPN3\",\n      \"pmids\": [\"27532629\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Endogenous signaling partners and downstream effectors in mammalian cells unresolved\",\n        \"In vivo physiological consequence of OPN3 photosensing not demonstrated\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstration that blue light triggers retinal-dependent Ca²⁺ transients in chick Müller glia via OPN3 provided the first link between OPN3 photosensing and intracellular calcium signaling in a native cell type.\",\n      \"evidence\": \"Ca²⁺ imaging with hydroxylamine-mediated retinal bleaching and OPN3 immunolocalization in Müller cells\",\n      \"pmids\": [\"31474836\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Specific G protein and channel mediating Ca²⁺ entry not identified\",\n        \"OPN3 knockdown/knockout not performed to confirm specificity\",\n        \"Whether this pathway operates in mammalian glia unknown\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Human genetic evidence linked OPN3 missense mutations to non-syndromic oligodontia and OPN3 protein was localized to tooth germ cells during embryogenesis, establishing an unexpected developmental role.\",\n      \"evidence\": \"Whole exome sequencing in oligodontia families with immunohistochemistry in mouse embryos\",\n      \"pmids\": [\"33611338\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No functional rescue or animal model confirming causality of the missense variants\",\n        \"Downstream signaling pathway in tooth development unknown\",\n        \"Light-dependent vs. light-independent mechanism not distinguished\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Multiple in vivo knockout studies revealed that OPN3 loss causes attenuated acoustic startle reflex and refractive myopia (from extra-retinal domains), demonstrating broad non-visual physiological roles and establishing that OPN3 functions outside classical photoreceptor cells.\",\n      \"evidence\": \"Opn3 germline vs. retina-conditional KO mice with acoustic startle testing, infrared photorefractor, and SD-OCT biometry\",\n      \"pmids\": [\"36041828\", \"37287644\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The cell type mediating extra-retinal myopia control not definitively identified\",\n        \"Mechanism linking OPN3 to startle circuit modulation unknown\",\n        \"Whether these phenotypes are light-dependent in vivo not tested\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"OPN3 was shown to physically interact with BRAFV600E to modulate ERK signaling and melanogenesis in a light-independent manner, revealing a non-canonical function as a signaling scaffold in melanocytic cells.\",\n      \"evidence\": \"Co-immunoprecipitation, siRNA knockdown, and overexpression in BRAFV600E congenital melanocytic nevus cells and 3D nevus models\",\n      \"pmids\": [\"35577105\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Co-IP performed in a single lab; reciprocal validation and domain mapping not shown\",\n        \"Whether the OPN3-BRAF interaction requires retinal not determined\",\n        \"Relevance to non-mutant BRAF signaling not established\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"A detailed OPN3-TRPV1-Ca²⁺-CaMKII signaling axis was delineated in melanocytes, connecting blue-light photosensing to dual outputs: PAX3-driven melanin synthesis and clusterin-LC3B-mediated inhibition of melanosome autophagy.\",\n      \"evidence\": \"siRNA knockdown, calcium imaging, western blotting, and co-immunoprecipitation of clusterin-LC3B in melanocytes\",\n      \"pmids\": [\"39241981\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct physical interaction between OPN3 and TRPV1 not demonstrated\",\n        \"Single-lab study; independent replication needed\",\n        \"Whether the autophagy branch operates in non-melanocytic cells unknown\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"OPN3 was found to physically complex with VEGFR2 at the plasma membrane and promote angiogenesis via the VEGFR2-AKT pathway, extending OPN3's non-canonical roles to vascular biology and confirmed by zebrafish knockout vascular phenotypes.\",\n      \"evidence\": \"Reciprocal co-immunoprecipitation, co-localization imaging, tube formation and sprouting assays in HUVECs, CRISPR knockout in zebrafish\",\n      \"pmids\": [\"40164822\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether OPN3-VEGFR2 interaction is light-dependent or light-independent not resolved\",\n        \"Structural basis of the OPN3-VEGFR2 complex unknown\",\n        \"In vivo relevance in mammalian vasculature not tested\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Opn3 knockout confirmed thermoregulatory deficits under cold stress and refractive myopia, and lineage tracing mapped Opn3-expressing cells primarily to olfactory bulb, cerebral cortex, thalamus, and cerebellum, refining the anatomical basis for OPN3's neural phenotypes.\",\n      \"evidence\": \"CRISPR knock-in of phiC31o reporter, telemetric body temperature monitoring, infrared photorefractor in KO mice\",\n      \"pmids\": [\"41102823\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism linking OPN3 to thermoregulation not defined\",\n        \"Recombination efficiency in some brain regions was modest (30–44%)\",\n        \"Whether thermoregulation phenotype is light-dependent not tested\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"A PPARα/p62-autophagy axis was defined as the mechanism by which OPN3 mediates blue-light-induced lipid droplet clearance in hepatocytes, expanding OPN3's physiological scope to lipid metabolism and antiviral defense.\",\n      \"evidence\": \"Opn3 KO hepatocytes, blue light irradiation with lipid droplet quantification, PPARα nuclear translocation imaging, p62 western blotting, viral replication assays\",\n      \"pmids\": [\"41594649\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"G protein coupling in hepatocytes not characterized\",\n        \"Whether hepatic retinal availability is sufficient for OPN3 function in vivo unknown\",\n        \"Antiviral mechanism downstream of OPN3 not molecularly defined\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis of OPN3's dual capacity for light-dependent signaling and light-independent protein scaffolding, the identity of its direct G protein partners in native mammalian tissues, and whether its diverse physiological roles (thermoregulation, startle modulation, tooth development) operate through retinal-dependent or retinal-independent mechanisms.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No high-resolution structure of OPN3 or its complexes with BRAFV600E or VEGFR2\",\n        \"Mammalian OPN3 has not been directly reconstituted as a photopigment (only homologs)\",\n        \"Light-dependence vs. light-independence of in vivo phenotypes not systematically tested\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [6, 12]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [6, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [12]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0162582\", \"supporting_discovery_ids\": [1, 6, 10, 12]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 6, 10, 12]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [10, 14]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [14]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [5, 8]},\n      {\"term_id\": \"R-HSA-9709957\", \"supporting_discovery_ids\": [1, 9]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"BRAF\",\n      \"VEGFR2\",\n      \"TRPV1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\nWait, I need to fix the pathway entries - I accidentally included a GO term. Let me correct:\n\n```json\n{\n  \"mechanistic_narrative\": \"OPN3 (encephalopsin) is a non-visual, bistable opsin that functions as a blue-light-sensitive G protein-coupled receptor in diverse extraocular tissues, coupling retinal photoisomerization to Gi/Go-type G protein activation and downstream calcium, cAMP, and MAPK signaling [PMID:23479626, PMID:27532629, PMID:39241981]. Beyond canonical light-dependent signaling—where it binds 11-cis retinal (~465 nm absorption maximum) and triggers TRPV1-mediated Ca²⁺ influx to regulate melanogenesis and autophagy [PMID:39241981, PMID:41594649]—OPN3 also engages in light-independent protein–protein interactions, physically complexing with BRAFV600E to modulate ERK-driven melanin production and with VEGFR2 to promote AKT-dependent angiogenesis [PMID:35577105, PMID:40164822]. Germline Opn3 knockout in mice produces refractive myopia originating from an extra-retinal expression domain, attenuated acoustic startle reflex, and impaired thermoregulation, while human OPN3 missense mutations co-segregate with non-syndromic oligodontia [PMID:37287644, PMID:36041828, PMID:41102823, PMID:33611338]. In hepatocytes, OPN3 mediates blue-light-induced lipid droplet clearance through a PPARα/p62-autophagy axis and suppresses viral replication [PMID:41594649].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"The discovery of OPN3 as the first mammalian extraocular opsin established that photoreceptive GPCRs exist in the brain, raising the question of whether OPN3 is a functional photopigment or an orphan receptor.\",\n      \"evidence\": \"In situ hybridization and Northern blot mapping of OPN3 mRNA in discrete mouse brain regions\",\n      \"pmids\": [\"10234000\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No demonstration that OPN3 binds retinal or absorbs light\",\n        \"No functional signaling activity measured\",\n        \"Peripheral tissue expression not systematically surveyed\"\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Reconstitution of OPN3 homologs as bistable, retinal-binding photopigments with Gi/Go coupling resolved the fundamental question of whether OPN3 is a bona fide light sensor, establishing its blue-to-green spectral sensitivity and G protein specificity.\",\n      \"evidence\": \"Heterologous expression with spectroscopic absorption measurement and cAMP/G protein activation assays for pufferfish and mosquito OPN3\",\n      \"pmids\": [\"23479626\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mammalian OPN3 itself was not directly reconstituted in this study\",\n        \"Downstream signaling pathways in native tissues unknown\",\n        \"Whether OPN3 has light-independent functions not addressed\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Characterization of vertebrate OPN3 orthologs confirmed a conserved ~465 nm blue-light absorption maximum and light-dependent G protein activation across species, solidifying OPN3 as a blue-light photopigment.\",\n      \"evidence\": \"Spectroscopy and chimeric opsin cAMP reporter assays with zebrafish, pufferfish, anole, and chicken OPN3\",\n      \"pmids\": [\"27532629\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Endogenous signaling partners and downstream effectors in mammalian cells unresolved\",\n        \"In vivo physiological consequence of OPN3 photosensing not demonstrated\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstration that blue light triggers retinal-dependent Ca²⁺ transients in chick Müller glia via OPN3 provided the first link between OPN3 photosensing and intracellular calcium signaling in a native cell type.\",\n      \"evidence\": \"Ca²⁺ imaging with hydroxylamine-mediated retinal bleaching and OPN3 immunolocalization in Müller cells\",\n      \"pmids\": [\"31474836\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Specific G protein and channel mediating Ca²⁺ entry not identified\",\n        \"OPN3 knockdown/knockout not performed to confirm specificity\",\n        \"Whether this pathway operates in mammalian glia unknown\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Human genetic evidence linked OPN3 missense mutations to non-syndromic oligodontia and OPN3 protein was localized to tooth germ cells during embryogenesis, establishing an unexpected developmental role.\",\n      \"evidence\": \"Whole exome sequencing in oligodontia families with immunohistochemistry in mouse embryos\",\n      \"pmids\": [\"33611338\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No functional rescue or animal model confirming causality of the missense variants\",\n        \"Downstream signaling pathway in tooth development unknown\",\n        \"Light-dependent vs. light-independent mechanism not distinguished\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Multiple in vivo knockout studies revealed that OPN3 loss causes attenuated acoustic startle reflex and refractive myopia (from extra-retinal domains), demonstrating broad non-visual physiological roles and establishing that OPN3 functions outside classical photoreceptor cells.\",\n      \"evidence\": \"Opn3 germline vs. retina-conditional KO mice with acoustic startle testing, infrared photorefractor, and SD-OCT biometry\",\n      \"pmids\": [\"36041828\", \"37287644\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The cell type mediating extra-retinal myopia control not definitively identified\",\n        \"Mechanism linking OPN3 to startle circuit modulation unknown\",\n        \"Whether these phenotypes are light-dependent in vivo not tested\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"OPN3 was shown to physically interact with BRAFV600E to modulate ERK signaling and melanogenesis in a light-independent manner, revealing a non-canonical function as a signaling scaffold in melanocytic cells.\",\n      \"evidence\": \"Co-immunoprecipitation, siRNA knockdown, and overexpression in BRAFV600E congenital melanocytic nevus cells and 3D nevus models\",\n      \"pmids\": [\"35577105\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Co-IP performed in a single lab; reciprocal validation and domain mapping not shown\",\n        \"Whether the OPN3-BRAF interaction requires retinal not determined\",\n        \"Relevance to non-mutant BRAF signaling not established\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"A detailed OPN3-TRPV1-Ca²⁺-CaMKII signaling axis was delineated in melanocytes, connecting blue-light photosensing to dual outputs: PAX3-driven melanin synthesis and clusterin-LC3B-mediated inhibition of melanosome autophagy.\",\n      \"evidence\": \"siRNA knockdown, calcium imaging, western blotting, and co-immunoprecipitation of clusterin-LC3B in melanocytes\",\n      \"pmids\": [\"39241981\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct physical interaction between OPN3 and TRPV1 not demonstrated\",\n        \"Single-lab study; independent replication needed\",\n        \"Whether the autophagy branch operates in non-melanocytic cells unknown\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"OPN3 was found to physically complex with VEGFR2 at the plasma membrane and promote angiogenesis via the VEGFR2-AKT pathway, extending OPN3's non-canonical roles to vascular biology and confirmed by zebrafish knockout vascular phenotypes.\",\n      \"evidence\": \"Reciprocal co-immunoprecipitation, co-localization imaging, tube formation and sprouting assays in HUVECs, CRISPR knockout in zebrafish\",\n      \"pmids\": [\"40164822\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether OPN3-VEGFR2 interaction is light-dependent or light-independent not resolved\",\n        \"Structural basis of the OPN3-VEGFR2 complex unknown\",\n        \"In vivo relevance in mammalian vasculature not tested\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Opn3 knockout confirmed thermoregulatory deficits under cold stress and refractive myopia, and lineage tracing mapped Opn3-expressing cells primarily to olfactory bulb, cerebral cortex, thalamus, and cerebellum, refining the anatomical basis for OPN3's neural phenotypes.\",\n      \"evidence\": \"CRISPR knock-in of phiC31o reporter, telemetric body temperature monitoring, infrared photorefractor in KO mice\",\n      \"pmids\": [\"41102823\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism linking OPN3 to thermoregulation not defined\",\n        \"Recombination efficiency in some brain regions was modest (30-44%)\",\n        \"Whether thermoregulation phenotype is light-dependent not tested\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"A PPARα/p62-autophagy axis was defined as the mechanism by which OPN3 mediates blue-light-induced lipid droplet clearance in hepatocytes, expanding OPN3's physiological scope to lipid metabolism and antiviral defense.\",\n      \"evidence\": \"Opn3 KO hepatocytes, blue light irradiation with lipid droplet quantification, PPARα nuclear translocation imaging, p62 western blotting, viral replication assays\",\n      \"pmids\": [\"41594649\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"G protein coupling in hepatocytes not characterized\",\n        \"Whether hepatic retinal availability is sufficient for OPN3 function in vivo unknown\",\n        \"Antiviral mechanism downstream of OPN3 not molecularly defined\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis of OPN3's dual capacity for light-dependent signaling and light-independent protein scaffolding, the identity of its direct G protein partners in native mammalian tissues, and whether its diverse physiological roles (thermoregulation, startle modulation, tooth development) operate through retinal-dependent or retinal-independent mechanisms.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No high-resolution structure of OPN3 or its complexes with BRAFV600E or VEGFR2\",\n        \"Mammalian OPN3 has not been directly reconstituted as a photopigment (only homologs)\",\n        \"Light-dependence vs. light-independence of in vivo phenotypes not systematically tested\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [6, 12]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [6, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [12]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 6, 10, 12]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [10, 14]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [14]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [5, 8]},\n      {\"term_id\": \"R-HSA-9709957\", \"supporting_discovery_ids\": [9]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"BRAF\",\n      \"KDR\",\n      \"TRPV1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}