{"gene":"NMBR","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":1994,"finding":"NMBR (NMB-R) undergoes homologous desensitization upon agonist stimulation via receptor internalization and down-regulation; receptor recovery at the cell surface after agonist removal is independent of new protein synthesis and depends on recycling from an intracellular compartment (blocked by monensin but not cycloheximide), and resensitization to NMB parallels receptor reappearance on the cell surface.","method":"Radioligand binding, [3H]inositol phosphate and [Ca2+]i assays, monensin and cycloheximide treatment in native C-6 glioblastoma cells and stably transfected Balb/3T3 cells expressing cloned rat NMB-R","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal functional assays (ligand binding, IP3 accumulation, Ca2+ imaging) with pharmacological dissection of recycling vs. synthesis in two independent cell systems","pmids":["8163469"],"is_preprint":false},{"year":2014,"finding":"NMBR and GRPR exhibit cross-inhibitory signaling such that loss of NMBR enhances GRPR activity (and vice versa) without upregulating receptor expression, maintaining normal histaminergic itch. GRPR+ neurons act downstream of NMBR+ neurons to integrate NMB-NMBR-encoded histaminergic itch information. NMB signals exclusively through NMBR, whereas GRP can signal through both receptors. NMBR and GRPR together are required for histaminergic itch but GRPR alone is required for chloroquine-evoked (nonhistaminergic) itch.","method":"Nmbr knockout mice, Grpr/Nmbr double-knockout mice, intradermal pruritogen injection with scratching behavior quantification, receptor expression analysis","journal":"The Journal of Neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis via single and double knockout mice with defined behavioral and molecular phenotypes, multiple pruritogens tested","pmids":["25209280"],"is_preprint":false},{"year":2021,"finding":"NMBR co-expressed with NPRC (BNP receptor) in spinal cord laminae I-II mediates cross-signaling: BNP binding to NPRC facilitates NMB-NMBR-encoded histaminergic itch through a Gq-coupled PLCβ-Ca2+ signaling pathway. BNP evoked Ca2+ responses specifically in cells co-expressing both NMBR and NPRC (HEK293 cells and dorsal horn neurons), and NPRC is required for histamine- but not chloroquine-evoked itch.","method":"Npr3 (NPRC) knockout mice, behavioral pruritogen assays, Ca2+ imaging in NMBR/NPRC HEK293 cells and dorsal horn neurons, immunofluorescence co-localization","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic knockout combined with in vitro Ca2+ signaling reconstitution in co-transfected cells and primary neurons, multiple behavioral assays","pmids":["34919054"],"is_preprint":false},{"year":2002,"finding":"Loss of NMBR in female mice results in elevated 5-HT immunoreactivity specifically in the dorsal raphe nucleus and downregulated 5-HT1A receptor gene expression at the whole-brain level, indicating that NMB/NMBR signaling modulates serotonergic neuronal activity in the dorsal raphe. 5-HT depletion by p-CPA reversed the decreased marble-burying behavior seen in NMBR-deficient mice.","method":"Nmbr knockout mice, marble burying behavioral assay, p-CPA pharmacological depletion of 5-HT, immunohistochemistry of brain sections, quantitative RT-PCR for 5-HT1A receptor, HPLC for brain 5-HT content","journal":"Brain Research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — single lab, genetic KO with behavioral and neurochemical readouts but indirect pathway placement","pmids":["12031854"],"is_preprint":false},{"year":2025,"finding":"NMB/NMBR signaling activates a positive feedback loop with the RIG-I innate immune pathway: NMBR activation upregulates TRIM25 (an E3 ubiquitin ligase that targets viral NS1) and promotes K63-linked ubiquitination of RIG-I while transcriptionally suppressing the deubiquitinase CYLD, resulting in enhanced JAK-STAT1 signaling (increased STAT1 phosphorylation) and elevated ISG15 expression, restricting H9N2 influenza virus replication.","method":"NMBR overexpression and knockdown in A549 cells and mouse lung infection model, IFN-β reporter assays, Western blot for STAT1 phosphorylation and ISG15, TRIM25/CYLD expression analysis, ubiquitination assays, viral replication measurement","journal":"Veterinary Microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — single lab, multiple mechanistic readouts (ubiquitination, phosphorylation, gene expression, viral replication) but not yet replicated","pmids":["41242095"],"is_preprint":false},{"year":2025,"finding":"NMB binding to NMBR activates phospholipase Cβ1 (PLCβ1), triggering endoplasmic reticulum Ca2+ release and raising cytosolic Ca2+ levels in granulosa cells. This Ca2+ signal promotes mitochondria-associated ER membrane (MAM) formation via the IRE1α–IP3R–VDAC1 axis, facilitating Ca2+ transfer to mitochondria, enhancing mitochondrial membrane potential, respiratory chain complex activities, and ATP production, ultimately promoting cell cycle progression (S-phase entry, upregulation of CCNE1 and CDK1/2/6). All effects were abolished by an NMBR antagonist.","method":"Exogenous NMB treatment and NMBR antagonist in goat granulosa cells; flow cytometry for cell cycle; Western blot for CCNE1, CDK1/2/6, PLCβ1, IRE1α, IP3R, VDAC1; Ca2+ imaging; mitochondrial membrane potential and ATP assays; ER stress markers","journal":"Journal of Ovarian Research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — single lab, multiple orthogonal cellular assays with pharmacological antagonist control, but no receptor mutagenesis or structural validation","pmids":["41257985"],"is_preprint":false},{"year":2002,"finding":"NMB-R-deficient female mice display impaired recovery of maternal behavior following restraint stress (30 min), with wild-type mice recovering to near-normal maternal behavior within 30 min post-stress while NMBR-null mice remain significantly impaired, establishing a role for NMB/NMBR signaling in stress resilience and stress-related behavioral recovery.","method":"Nmbr knockout mice, restraint stress paradigm, maternal behavior scoring","journal":"Neuroscience Letters","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single behavioral KO study, single lab, no molecular mechanism identified","pmids":["12231437"],"is_preprint":false}],"current_model":"NMBR is a Gq-coupled receptor that, upon NMB binding, activates PLCβ signaling to generate IP3/DAG and elevate intracellular Ca2+; it undergoes agonist-induced internalization and recycling-dependent resensitization; in the spinal cord it cross-inhibits GRPR to maintain histaminergic itch transmission (with GRPR+ neurons acting downstream of NMBR+ neurons), and can be transactivated by NPRC-bound BNP to amplify NMB-encoded itch; in peripheral cells it promotes mitochondrial Ca2+ uptake via the IRE1α–IP3R–VDAC1 MAM axis to drive proliferation; and in innate immune contexts it amplifies RIG-I/TRIM25/STAT1 antiviral signaling while suppressing the deubiquitinase CYLD."},"narrative":{"mechanistic_narrative":"NMBR is a Gq-coupled receptor for neuromedin B (NMB) that signals through phospholipase Cβ to mobilize intracellular Ca2+, governing sensory itch transmission, cell proliferation, and innate antiviral responses [PMID:34919054, PMID:41257985]. Upon agonist binding it undergoes homologous desensitization through internalization and down-regulation, with surface recovery and resensitization depending on recycling from an intracellular compartment rather than new protein synthesis [PMID:8163469]. In the spinal cord, NMBR mediates histaminergic itch and engages in cross-inhibitory signaling with GRPR, with GRPR+ neurons acting downstream of NMBR+ neurons to integrate NMB-encoded itch information; NMB signals exclusively through NMBR while GRP can act through both receptors [PMID:25209280]. NMBR-encoded histaminergic itch is amplified when BNP-bound NPRC, co-expressed with NMBR, facilitates the receptor's Gq–PLCβ–Ca2+ signaling [PMID:34919054]. Beyond sensory neurons, NMB-NMBR-driven PLCβ1 activation and ER Ca2+ release promote MAM formation through the IRE1α–IP3R–VDAC1 axis to enhance mitochondrial Ca2+ uptake, respiration, and cell-cycle progression [PMID:41257985], and NMBR activation amplifies RIG-I/TRIM25/STAT1 antiviral signaling while suppressing the deubiquitinase CYLD to restrict influenza replication [PMID:41242095]. NMBR signaling additionally modulates serotonergic activity in the dorsal raphe and influences stress-related behavior [PMID:12031854].","teleology":[{"year":1994,"claim":"Established that NMBR is a desensitizing GPCR whose signaling capacity is restored not by new receptor synthesis but by recycling of internalized receptor back to the cell surface, defining the basis of its resensitization.","evidence":"Radioligand binding, inositol phosphate and Ca2+ assays with monensin/cycloheximide dissection in glioblastoma and transfected fibroblast cells","pmids":["8163469"],"confidence":"High","gaps":["Identity of the recycling compartment and trafficking machinery not defined","No mapping of receptor residues controlling internalization"]},{"year":2002,"claim":"Linked NMBR signaling to central neuromodulation by showing its loss alters serotonergic tone in the dorsal raphe and downstream behavior, extending NMBR function beyond peripheral signaling.","evidence":"Nmbr knockout mice with behavioral assays, p-CPA 5-HT depletion, immunohistochemistry, RT-PCR and HPLC for 5-HT and 5-HT1A","pmids":["12031854"],"confidence":"Medium","gaps":["Pathway placement is indirect","No direct circuit-level connection between NMBR neurons and raphe serotonergic cells","Sex-specific effects unexplained"]},{"year":2002,"claim":"Implicated NMBR in stress resilience by showing receptor-null mice fail to recover behavior after acute restraint stress.","evidence":"Nmbr knockout mice subjected to restraint stress with maternal behavior scoring","pmids":["12231437"],"confidence":"Low","gaps":["Single behavioral knockout study with no molecular mechanism","No identification of relevant neural substrate","Not independently confirmed"]},{"year":2014,"claim":"Resolved how NMBR and GRPR partition itch modalities, establishing cross-inhibitory signaling and a NMBR→GRPR neuronal hierarchy that maintains histaminergic itch.","evidence":"Single and double Nmbr/Grpr knockout mice with intradermal pruritogen challenge and scratching quantification","pmids":["25209280"],"confidence":"High","gaps":["Molecular basis of receptor cross-inhibition unknown","Mechanism of ligand selectivity (NMB vs GRP) not defined"]},{"year":2021,"claim":"Identified BNP-NPRC as a heterologous facilitator of NMBR signaling, showing co-expressed NPRC amplifies NMB-encoded histaminergic itch through NMBR's Gq–PLCβ–Ca2+ pathway.","evidence":"Npr3 knockout mice, pruritogen behavioral assays, Ca2+ imaging in co-transfected HEK293 cells and dorsal horn neurons, immunofluorescence co-localization","pmids":["34919054"],"confidence":"High","gaps":["Physical mode of NMBR-NPRC functional coupling not resolved","How NPRC, a clearance receptor, transduces a Gq signal unexplained"]},{"year":2025,"claim":"Defined a peripheral proliferative role for NMBR, linking PLCβ1-driven ER Ca2+ release to MAM-mediated mitochondrial Ca2+ uptake and cell-cycle entry in granulosa cells.","evidence":"Exogenous NMB and NMBR antagonist in goat granulosa cells with cell-cycle flow cytometry, Western blot of MAM axis proteins, Ca2+ imaging, mitochondrial function assays","pmids":["41257985"],"confidence":"Medium","gaps":["Single lab, no receptor mutagenesis or structural validation","Generalizability beyond granulosa cells untested","Direct demonstration of receptor-IRE1α coupling absent"]},{"year":2025,"claim":"Placed NMBR in innate antiviral immunity, showing it amplifies RIG-I/TRIM25/STAT1 signaling and suppresses CYLD to restrict influenza replication.","evidence":"NMBR overexpression/knockdown in A549 cells and mouse lung infection, IFN-β reporters, ubiquitination assays, STAT1 phosphorylation and ISG15 Western blot, viral replication measurement","pmids":["41242095"],"confidence":"Medium","gaps":["Single lab, not independently replicated","Mechanism linking NMBR Gq signaling to TRIM25/CYLD regulation unclear","Whether endogenous NMB ligand drives this in vivo unknown"]},{"year":null,"claim":"How NMBR's single Gq-PLCβ-Ca2+ signaling module is differentially routed to produce distinct outcomes across sensory neurons, proliferating cells, and immune cells remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of NMBR or its ligand-receptor interface in the corpus","Mechanism of context-specific downstream coupling unknown","Cross-talk partners (GRPR, NPRC) lack defined physical interaction data"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,2,5]},{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,2,5]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[1,2]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[5]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[4]}],"complexes":[],"partners":["GRPR","NPRC"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P28336","full_name":"Neuromedin-B receptor","aliases":["Epididymis tissue protein Li 185a","Neuromedin-B-preferring bombesin receptor"],"length_aa":390,"mass_kda":43.4,"function":"Receptor for neuromedin-B (PubMed:1655761). Contributes to the maintenance of basal sigh rate through signaling in the pre-Botzinger complex, a cluster of several thousand neurons in the ventrolateral medulla responsible for inspiration during respiratory activity (By similarity). Contributes to the induction of sneezing following exposure to chemical irritants or allergens which causes release of NMB by nasal sensory neurons and activation of NMBR-expressing neurons in the sneeze-evoking region of the brainstem (By similarity). These in turn activate neurons of the caudal ventral respiratory group, giving rise to the sneezing response (By similarity). Contributes to induction of acute itch, possibly through its activation on dorsal root ganglion neurons by the NMB peptide (By similarity). Plays a role in the innate immune response to influenza A virus infection by enhancing interferon alpha expression and reducing expression of IL6 (PubMed:31601264). Plays a role in CSF1-induced proliferation of osteoclast precursors by contributing to the positive regulation of the expression of the CSF1 receptor CSF1R (By similarity)","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/P28336/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/NMBR","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/NMBR","total_profiled":1310},"omim":[{"mim_id":"305670","title":"GASTRIN-RELEASING PEPTIDE RECEPTOR; GRPR","url":"https://www.omim.org/entry/305670"},{"mim_id":"162341","title":"NEUROMEDIN B RECEPTOR; NMBR","url":"https://www.omim.org/entry/162341"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Plasma membrane","reliability":"Supported"},{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Not detected","tissue_distribution":"Not detected","driving_tissues":[],"url":"https://www.proteinatlas.org/search/NMBR"},"hgnc":{"alias_symbol":["BB1","BB1R","BRS1"],"prev_symbol":[]},"alphafold":{"accession":"P28336","domains":[{"cath_id":"1.20.1070.10","chopping":"36-244_257-337","consensus_level":"high","plddt":92.6684,"start":36,"end":337}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P28336","model_url":"https://alphafold.ebi.ac.uk/files/AF-P28336-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P28336-F1-predicted_aligned_error_v6.png","plddt_mean":79.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=NMBR","jax_strain_url":"https://www.jax.org/strain/search?query=NMBR"},"sequence":{"accession":"P28336","fasta_url":"https://rest.uniprot.org/uniprotkb/P28336.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P28336/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P28336"}},"corpus_meta":[{"pmid":"22840528","id":"PMC_22840528","title":"Spectrum and prevalence of mutations involving BrS1- through BrS12-susceptibility genes in a cohort of unrelated patients referred for Brugada syndrome genetic testing: implications for genetic testing.","date":"2012","source":"Journal of the American College of Cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/22840528","citation_count":152,"is_preprint":false},{"pmid":"25209280","id":"PMC_25209280","title":"Cross-inhibition of NMBR and GRPR signaling maintains normal histaminergic itch transmission.","date":"2014","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/25209280","citation_count":50,"is_preprint":false},{"pmid":"8163469","id":"PMC_8163469","title":"Desensitization of neuromedin B receptors (NMB-R) on native and NMB-R-transfected cells involves down-regulation and internalization.","date":"1994","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8163469","citation_count":36,"is_preprint":false},{"pmid":"28500250","id":"PMC_28500250","title":"Characterization of NMB, GRP and their receptors (BRS3, NMBR and GRPR) in chickens.","date":"2017","source":"Journal of molecular endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/28500250","citation_count":27,"is_preprint":false},{"pmid":"12231437","id":"PMC_12231437","title":"Restraint stress impaired maternal behavior in female mice lacking the neuromedin B receptor (NMB-R) gene.","date":"2002","source":"Neuroscience letters","url":"https://pubmed.ncbi.nlm.nih.gov/12231437","citation_count":26,"is_preprint":false},{"pmid":"9248010","id":"PMC_9248010","title":"BRS1, a C30 bis-amino, bis-hydroxy polyunsaturated lipid from an Australian calcareous sponge that inhibits protein kinase C.","date":"1997","source":"Toxicon : official journal of the International Society on Toxinology","url":"https://pubmed.ncbi.nlm.nih.gov/9248010","citation_count":25,"is_preprint":false},{"pmid":"12031854","id":"PMC_12031854","title":"Decreased marble burying behavior in female mice lacking neuromedin-B receptor (NMB-R) implies the involvement of NMB/NMB-R in 5-HT neuron function.","date":"2002","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/12031854","citation_count":25,"is_preprint":false},{"pmid":"34919054","id":"PMC_34919054","title":"BNP facilitates NMB-encoded histaminergic itch via NPRC-NMBR crosstalk.","date":"2021","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/34919054","citation_count":21,"is_preprint":false},{"pmid":"27092952","id":"PMC_27092952","title":"PDE7B, NMBR and EPM2A Variants and Schizophrenia: A Case-Control and Pharmacogenetics Study.","date":"2016","source":"Neuropsychobiology","url":"https://pubmed.ncbi.nlm.nih.gov/27092952","citation_count":11,"is_preprint":false},{"pmid":"34116634","id":"PMC_34116634","title":"BRS1 mediates plant redox regulation and cold responses.","date":"2021","source":"BMC plant biology","url":"https://pubmed.ncbi.nlm.nih.gov/34116634","citation_count":5,"is_preprint":false},{"pmid":"19587437","id":"PMC_19587437","title":"[Expression of NMBR in myometrium in pregnant mice at different gestational ages and its relation with parturition].","date":"2009","source":"Zhong nan da xue xue bao. Yi xue ban = Journal of Central South University. Medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/19587437","citation_count":2,"is_preprint":false},{"pmid":"41242095","id":"PMC_41242095","title":"Neuromedin B and its receptor NMBR inhibit H9N2 infection.","date":"2025","source":"Veterinary microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/41242095","citation_count":0,"is_preprint":false},{"pmid":"41257985","id":"PMC_41257985","title":"Neuromedin B drives goat granulosa cell proliferation via NMBR-mediated calcium homeostasis.","date":"2025","source":"Journal of ovarian research","url":"https://pubmed.ncbi.nlm.nih.gov/41257985","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8949,"output_tokens":2303,"usd":0.030696,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9414,"output_tokens":2877,"usd":0.059498,"stage2_stop_reason":"end_turn"},"total_usd":0.090194,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1994,\n      \"finding\": \"NMBR (NMB-R) undergoes homologous desensitization upon agonist stimulation via receptor internalization and down-regulation; receptor recovery at the cell surface after agonist removal is independent of new protein synthesis and depends on recycling from an intracellular compartment (blocked by monensin but not cycloheximide), and resensitization to NMB parallels receptor reappearance on the cell surface.\",\n      \"method\": \"Radioligand binding, [3H]inositol phosphate and [Ca2+]i assays, monensin and cycloheximide treatment in native C-6 glioblastoma cells and stably transfected Balb/3T3 cells expressing cloned rat NMB-R\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal functional assays (ligand binding, IP3 accumulation, Ca2+ imaging) with pharmacological dissection of recycling vs. synthesis in two independent cell systems\",\n      \"pmids\": [\"8163469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"NMBR and GRPR exhibit cross-inhibitory signaling such that loss of NMBR enhances GRPR activity (and vice versa) without upregulating receptor expression, maintaining normal histaminergic itch. GRPR+ neurons act downstream of NMBR+ neurons to integrate NMB-NMBR-encoded histaminergic itch information. NMB signals exclusively through NMBR, whereas GRP can signal through both receptors. NMBR and GRPR together are required for histaminergic itch but GRPR alone is required for chloroquine-evoked (nonhistaminergic) itch.\",\n      \"method\": \"Nmbr knockout mice, Grpr/Nmbr double-knockout mice, intradermal pruritogen injection with scratching behavior quantification, receptor expression analysis\",\n      \"journal\": \"The Journal of Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis via single and double knockout mice with defined behavioral and molecular phenotypes, multiple pruritogens tested\",\n      \"pmids\": [\"25209280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"NMBR co-expressed with NPRC (BNP receptor) in spinal cord laminae I-II mediates cross-signaling: BNP binding to NPRC facilitates NMB-NMBR-encoded histaminergic itch through a Gq-coupled PLCβ-Ca2+ signaling pathway. BNP evoked Ca2+ responses specifically in cells co-expressing both NMBR and NPRC (HEK293 cells and dorsal horn neurons), and NPRC is required for histamine- but not chloroquine-evoked itch.\",\n      \"method\": \"Npr3 (NPRC) knockout mice, behavioral pruritogen assays, Ca2+ imaging in NMBR/NPRC HEK293 cells and dorsal horn neurons, immunofluorescence co-localization\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout combined with in vitro Ca2+ signaling reconstitution in co-transfected cells and primary neurons, multiple behavioral assays\",\n      \"pmids\": [\"34919054\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Loss of NMBR in female mice results in elevated 5-HT immunoreactivity specifically in the dorsal raphe nucleus and downregulated 5-HT1A receptor gene expression at the whole-brain level, indicating that NMB/NMBR signaling modulates serotonergic neuronal activity in the dorsal raphe. 5-HT depletion by p-CPA reversed the decreased marble-burying behavior seen in NMBR-deficient mice.\",\n      \"method\": \"Nmbr knockout mice, marble burying behavioral assay, p-CPA pharmacological depletion of 5-HT, immunohistochemistry of brain sections, quantitative RT-PCR for 5-HT1A receptor, HPLC for brain 5-HT content\",\n      \"journal\": \"Brain Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — single lab, genetic KO with behavioral and neurochemical readouts but indirect pathway placement\",\n      \"pmids\": [\"12031854\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"NMB/NMBR signaling activates a positive feedback loop with the RIG-I innate immune pathway: NMBR activation upregulates TRIM25 (an E3 ubiquitin ligase that targets viral NS1) and promotes K63-linked ubiquitination of RIG-I while transcriptionally suppressing the deubiquitinase CYLD, resulting in enhanced JAK-STAT1 signaling (increased STAT1 phosphorylation) and elevated ISG15 expression, restricting H9N2 influenza virus replication.\",\n      \"method\": \"NMBR overexpression and knockdown in A549 cells and mouse lung infection model, IFN-β reporter assays, Western blot for STAT1 phosphorylation and ISG15, TRIM25/CYLD expression analysis, ubiquitination assays, viral replication measurement\",\n      \"journal\": \"Veterinary Microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — single lab, multiple mechanistic readouts (ubiquitination, phosphorylation, gene expression, viral replication) but not yet replicated\",\n      \"pmids\": [\"41242095\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"NMB binding to NMBR activates phospholipase Cβ1 (PLCβ1), triggering endoplasmic reticulum Ca2+ release and raising cytosolic Ca2+ levels in granulosa cells. This Ca2+ signal promotes mitochondria-associated ER membrane (MAM) formation via the IRE1α–IP3R–VDAC1 axis, facilitating Ca2+ transfer to mitochondria, enhancing mitochondrial membrane potential, respiratory chain complex activities, and ATP production, ultimately promoting cell cycle progression (S-phase entry, upregulation of CCNE1 and CDK1/2/6). All effects were abolished by an NMBR antagonist.\",\n      \"method\": \"Exogenous NMB treatment and NMBR antagonist in goat granulosa cells; flow cytometry for cell cycle; Western blot for CCNE1, CDK1/2/6, PLCβ1, IRE1α, IP3R, VDAC1; Ca2+ imaging; mitochondrial membrane potential and ATP assays; ER stress markers\",\n      \"journal\": \"Journal of Ovarian Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — single lab, multiple orthogonal cellular assays with pharmacological antagonist control, but no receptor mutagenesis or structural validation\",\n      \"pmids\": [\"41257985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"NMB-R-deficient female mice display impaired recovery of maternal behavior following restraint stress (30 min), with wild-type mice recovering to near-normal maternal behavior within 30 min post-stress while NMBR-null mice remain significantly impaired, establishing a role for NMB/NMBR signaling in stress resilience and stress-related behavioral recovery.\",\n      \"method\": \"Nmbr knockout mice, restraint stress paradigm, maternal behavior scoring\",\n      \"journal\": \"Neuroscience Letters\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single behavioral KO study, single lab, no molecular mechanism identified\",\n      \"pmids\": [\"12231437\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"NMBR is a Gq-coupled receptor that, upon NMB binding, activates PLCβ signaling to generate IP3/DAG and elevate intracellular Ca2+; it undergoes agonist-induced internalization and recycling-dependent resensitization; in the spinal cord it cross-inhibits GRPR to maintain histaminergic itch transmission (with GRPR+ neurons acting downstream of NMBR+ neurons), and can be transactivated by NPRC-bound BNP to amplify NMB-encoded itch; in peripheral cells it promotes mitochondrial Ca2+ uptake via the IRE1α–IP3R–VDAC1 MAM axis to drive proliferation; and in innate immune contexts it amplifies RIG-I/TRIM25/STAT1 antiviral signaling while suppressing the deubiquitinase CYLD.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"NMBR is a Gq-coupled receptor for neuromedin B (NMB) that signals through phospholipase Cβ to mobilize intracellular Ca2+, governing sensory itch transmission, cell proliferation, and innate antiviral responses [#2, #5]. Upon agonist binding it undergoes homologous desensitization through internalization and down-regulation, with surface recovery and resensitization depending on recycling from an intracellular compartment rather than new protein synthesis [#0]. In the spinal cord, NMBR mediates histaminergic itch and engages in cross-inhibitory signaling with GRPR, with GRPR+ neurons acting downstream of NMBR+ neurons to integrate NMB-encoded itch information; NMB signals exclusively through NMBR while GRP can act through both receptors [#1]. NMBR-encoded histaminergic itch is amplified when BNP-bound NPRC, co-expressed with NMBR, facilitates the receptor's Gq–PLCβ–Ca2+ signaling [#2]. Beyond sensory neurons, NMB-NMBR-driven PLCβ1 activation and ER Ca2+ release promote MAM formation through the IRE1α–IP3R–VDAC1 axis to enhance mitochondrial Ca2+ uptake, respiration, and cell-cycle progression [#5], and NMBR activation amplifies RIG-I/TRIM25/STAT1 antiviral signaling while suppressing the deubiquitinase CYLD to restrict influenza replication [#4]. NMBR signaling additionally modulates serotonergic activity in the dorsal raphe and influences stress-related behavior [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Established that NMBR is a desensitizing GPCR whose signaling capacity is restored not by new receptor synthesis but by recycling of internalized receptor back to the cell surface, defining the basis of its resensitization.\",\n      \"evidence\": \"Radioligand binding, inositol phosphate and Ca2+ assays with monensin/cycloheximide dissection in glioblastoma and transfected fibroblast cells\",\n      \"pmids\": [\"8163469\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the recycling compartment and trafficking machinery not defined\", \"No mapping of receptor residues controlling internalization\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Linked NMBR signaling to central neuromodulation by showing its loss alters serotonergic tone in the dorsal raphe and downstream behavior, extending NMBR function beyond peripheral signaling.\",\n      \"evidence\": \"Nmbr knockout mice with behavioral assays, p-CPA 5-HT depletion, immunohistochemistry, RT-PCR and HPLC for 5-HT and 5-HT1A\",\n      \"pmids\": [\"12031854\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Pathway placement is indirect\", \"No direct circuit-level connection between NMBR neurons and raphe serotonergic cells\", \"Sex-specific effects unexplained\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Implicated NMBR in stress resilience by showing receptor-null mice fail to recover behavior after acute restraint stress.\",\n      \"evidence\": \"Nmbr knockout mice subjected to restraint stress with maternal behavior scoring\",\n      \"pmids\": [\"12231437\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single behavioral knockout study with no molecular mechanism\", \"No identification of relevant neural substrate\", \"Not independently confirmed\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Resolved how NMBR and GRPR partition itch modalities, establishing cross-inhibitory signaling and a NMBR→GRPR neuronal hierarchy that maintains histaminergic itch.\",\n      \"evidence\": \"Single and double Nmbr/Grpr knockout mice with intradermal pruritogen challenge and scratching quantification\",\n      \"pmids\": [\"25209280\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of receptor cross-inhibition unknown\", \"Mechanism of ligand selectivity (NMB vs GRP) not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified BNP-NPRC as a heterologous facilitator of NMBR signaling, showing co-expressed NPRC amplifies NMB-encoded histaminergic itch through NMBR's Gq–PLCβ–Ca2+ pathway.\",\n      \"evidence\": \"Npr3 knockout mice, pruritogen behavioral assays, Ca2+ imaging in co-transfected HEK293 cells and dorsal horn neurons, immunofluorescence co-localization\",\n      \"pmids\": [\"34919054\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physical mode of NMBR-NPRC functional coupling not resolved\", \"How NPRC, a clearance receptor, transduces a Gq signal unexplained\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined a peripheral proliferative role for NMBR, linking PLCβ1-driven ER Ca2+ release to MAM-mediated mitochondrial Ca2+ uptake and cell-cycle entry in granulosa cells.\",\n      \"evidence\": \"Exogenous NMB and NMBR antagonist in goat granulosa cells with cell-cycle flow cytometry, Western blot of MAM axis proteins, Ca2+ imaging, mitochondrial function assays\",\n      \"pmids\": [\"41257985\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, no receptor mutagenesis or structural validation\", \"Generalizability beyond granulosa cells untested\", \"Direct demonstration of receptor-IRE1α coupling absent\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Placed NMBR in innate antiviral immunity, showing it amplifies RIG-I/TRIM25/STAT1 signaling and suppresses CYLD to restrict influenza replication.\",\n      \"evidence\": \"NMBR overexpression/knockdown in A549 cells and mouse lung infection, IFN-β reporters, ubiquitination assays, STAT1 phosphorylation and ISG15 Western blot, viral replication measurement\",\n      \"pmids\": [\"41242095\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, not independently replicated\", \"Mechanism linking NMBR Gq signaling to TRIM25/CYLD regulation unclear\", \"Whether endogenous NMB ligand drives this in vivo unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How NMBR's single Gq-PLCβ-Ca2+ signaling module is differentially routed to produce distinct outcomes across sensory neurons, proliferating cells, and immune cells remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of NMBR or its ligand-receptor interface in the corpus\", \"Mechanism of context-specific downstream coupling unknown\", \"Cross-talk partners (GRPR, NPRC) lack defined physical interaction data\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 2, 5]},\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 5]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"GRPR\", \"NPRC\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}