{"gene":"AVPR1B","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2013,"finding":"AVPR1B is the receptor responsible for desmopressin (DDAVP)-induced ACTH secretion selectively in corticotropinoma cells but not in normal pituitary or other adenoma cells. Desmopressin triggered Ca2+ kinetics, ACTH expression/release, and proliferative responses in corticotropinoma primary cultures; an AVPR1B-selective antagonist completely blocked these effects. AVPR1B expression levels in corticotropinomas were dramatically elevated and positively correlated with plasma ACTH levels.","method":"Primary cultures of human corticotropinomas and other pituitary adenomas treated with desmopressin ± selective AVPR1B antagonist; [Ca2+]i kinetics, ACTH secretion/expression assays, quantitative RT-PCR of AVPR expression","journal":"The Journal of clinical endocrinology and metabolism","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Ca2+ imaging, ACTH secretion assay, receptor antagonist blockade, qRT-PCR) in primary human tissue; mechanistic claim directly supported by pharmacological rescue","pmids":["23884782"],"is_preprint":false},{"year":2010,"finding":"Avpr1b on anterior pituitary corticotrophs mediates AVP-stimulated ACTH release in response to acute stress. Both genetic knockout of Avpr1b and pharmacological blockade with a novel Avpr1b antagonist significantly reduced plasma ACTH increases following acute restraint and forced swimming stress. Plasma corticosterone was also reduced in male (but not female) knockout or antagonist-treated mice under restraint stress.","method":"Avpr1b knockout mice vs. wild-type; selective Avpr1b antagonist administration; plasma ACTH and corticosterone measurements after acute stress","journal":"Journal of neuroendocrinology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO corroborated by pharmacological antagonism with two orthogonal approaches across multiple stress paradigms","pmids":["20846299"],"is_preprint":false},{"year":2013,"finding":"V1bR (AVPR1B) blockade with the selective antagonist Nelivaptan negatively affected the increase in blood ACTH caused by acute heat stress in rats, directly confirming the positive role of AVP in regulating ACTH secretion from the pituitary via V1bR. Circulating AVP was found to influence intrapituitary V1bR levels under heat stress conditions.","method":"Rat heat-stress model; Nelivaptan (selective V1bR antagonist) treatment; plasma ACTH/corticosterone by ELISA/chemiluminescence; intrapituitary V1bR and ACTH by western blot","journal":"The Journal of experimental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological blockade with functional hormone readouts, single lab, two orthogonal protein-level endpoints","pmids":["23580725"],"is_preprint":false},{"year":2008,"finding":"Avpr1b in the dorsal hippocampus, but not the ventral hippocampus, mediates anxiety-related behavior in rats. Microinfusion of a selective Avpr1b antagonist (SSR 149415) into the dorsal hippocampus reduced anxiety-like behavior in the elevated plus-maze, whereas the same treatment in the ventral hippocampus had no effect. Neither antagonist reduced anxiety in the shock-probe burying test, indicating response specificity.","method":"Stereotaxic microinfusion of selective Avpr1b antagonist (SSR 149415) into dorsal or ventral hippocampus of rats; elevated plus-maze and shock-probe burying behavioral tests","journal":"Neuropeptides","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — site-specific pharmacological antagonism with behavioral dissociation, single lab","pmids":["18508119"],"is_preprint":false},{"year":2022,"finding":"USP8 mutations in corticotropinoma cells upregulate AVPR1B promoter activity, thereby increasing AVPR1B expression and enhancing ACTH responsiveness to desmopressin (DDAVP) stimulation in Cushing's disease. DDAVP responsiveness correlated with AVPR1B (but not AVPR2) expression levels, and overexpression of mutant USP8 enhanced Avpr1b promoter activity compared to wild-type USP8.","method":"qRT-PCR and immunohistochemistry of AVP receptor expression in 47 Cushing's disease tumor samples; dual-luciferase reporter assay of AVPR1B promoter activity with mutant vs. wild-type USP8 overexpression","journal":"Pituitary","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — luciferase reporter assay plus clinical correlation, single lab, two orthogonal methods","pmids":["35451730"],"is_preprint":false},{"year":2024,"finding":"V1bR (AVPR1B) is expressed exclusively in pancreatic α cells (not β cells). AVP activates V1bR on α cells to stimulate glucagon secretion, and the secreted glucagon then promotes glucose-dependent insulin secretion from β cells in a paracrine manner by activating GLP-1R (but not GCGR) on β cells. AVP-induced insulin secretion from whole islets (but not isolated β cells) was blocked by a V1bR-selective antagonist.","method":"Single-cell transcriptome analysis of islet cell V1bR expression; AVP stimulation of isolated islets vs. purified β cells; V1bR-selective antagonist blockade; glucagon secretion assay; GLP-1R and GCGR antagonist experiments","journal":"Cell & bioscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (scRNA-seq, pharmacological blockade, receptor-specific antagonists), single lab","pmids":["39217353"],"is_preprint":false}],"current_model":"AVPR1B (V1bR) is a G protein-coupled receptor expressed on anterior pituitary corticotrophs and pancreatic α cells that: (1) mediates AVP-stimulated ACTH release in response to acute stress via HPA axis signaling, with genetic knockout or pharmacological antagonism reducing stress-induced ACTH and corticosterone; (2) drives desmopressin-induced ACTH hypersecretion in Cushing's disease corticotropinomas, where its promoter is upregulated by USP8 mutations; (3) mediates a paracrine α-to-β cell crosstalk in pancreatic islets whereby AVP/V1bR-stimulated glucagon secretion promotes glucose-dependent insulin release via GLP-1R; and (4) in the dorsal hippocampus, modulates anxiety-related behavior, with subregion-specific pharmacological dissociation from the Avpr1a subtype."},"narrative":{"mechanistic_narrative":"AVPR1B (V1bR) is a vasopressin-responsive G protein-coupled receptor that couples AVP signaling to neuroendocrine, behavioral, and metabolic outputs [PMID:20846299, PMID:39217353]. On anterior pituitary corticotrophs it mediates AVP-stimulated ACTH release during acute stress, since genetic knockout and selective pharmacological antagonism both blunt stress-induced ACTH and corticosterone responses [PMID:20846299], an effect confirmed across additional stress paradigms and species by antagonist blockade [PMID:23580725]. In Cushing's disease corticotropinomas, AVPR1B is dramatically overexpressed and drives desmopressin-induced ACTH hypersecretion and proliferative/Ca2+ responses that are abolished by an AVPR1B-selective antagonist, with receptor levels correlating with plasma ACTH [PMID:23884782]; this overexpression is driven by USP8 mutations that upregulate AVPR1B promoter activity [PMID:35451730]. Beyond the HPA axis, AVPR1B is expressed exclusively in pancreatic α cells, where AVP-stimulated glucagon secretion promotes glucose-dependent insulin release from β cells via paracrine GLP-1R signaling [PMID:39217353], and in the dorsal hippocampus it modulates anxiety-related behavior in a subregion-specific manner [PMID:18508119].","teleology":[{"year":2008,"claim":"Established that AVPR1B has a central behavioral role beyond endocrine signaling, anatomically localized to the dorsal hippocampus.","evidence":"Site-specific microinfusion of selective Avpr1b antagonist into dorsal vs. ventral hippocampus with elevated plus-maze and shock-probe behavioral tests in rats","pmids":["18508119"],"confidence":"Medium","gaps":["Single lab pharmacological study","Downstream circuit and signaling mechanism in hippocampus not defined","Endogenous AVP source driving the response not identified"]},{"year":2010,"claim":"Demonstrated by genetic and pharmacological convergence that pituitary Avpr1b is required for AVP-driven ACTH release during acute stress, defining its core HPA-axis function.","evidence":"Avpr1b knockout mice and selective antagonist treatment with plasma ACTH/corticosterone measurement after restraint and swim stress","pmids":["20846299"],"confidence":"High","gaps":["Sex-dependent corticosterone effect not mechanistically explained","Intracellular signaling coupling not resolved"]},{"year":2013,"claim":"Identified AVPR1B as the receptor underlying aberrant desmopressin-induced ACTH secretion specifically in corticotropinomas, linking receptor overexpression to disease.","evidence":"Primary cultures of human corticotropinomas and other adenomas with desmopressin ± selective antagonist; Ca2+ imaging, ACTH secretion/expression, qRT-PCR","pmids":["23884782"],"confidence":"High","gaps":["Cause of receptor overexpression not yet established at this stage","Link between Ca2+ signaling and proliferation not detailed"]},{"year":2013,"claim":"Confirmed across species and stress modality that V1bR antagonism blunts ACTH, reinforcing AVP's positive regulation of pituitary ACTH.","evidence":"Rat heat-stress model with Nelivaptan; plasma ACTH/corticosterone and intrapituitary V1bR/ACTH by western blot","pmids":["23580725"],"confidence":"Medium","gaps":["Single lab","Regulation of intrapituitary V1bR levels by circulating AVP not mechanistically dissected"]},{"year":2022,"claim":"Connected AVPR1B overexpression in Cushing's disease to a transcriptional driver, showing USP8 mutations upregulate the AVPR1B promoter.","evidence":"qRT-PCR/IHC of AVP receptors in 47 Cushing's disease tumors plus dual-luciferase AVPR1B promoter assay with mutant vs. wild-type USP8","pmids":["35451730"],"confidence":"Medium","gaps":["Mechanism by which mutant USP8 activates the promoter not defined","Single lab","Selectivity of effect on AVPR1B vs. AVPR2 not fully resolved"]},{"year":2024,"claim":"Extended AVPR1B function to metabolic regulation, defining an α-cell-restricted receptor that orchestrates paracrine α-to-β cell crosstalk.","evidence":"Single-cell transcriptomics of islet V1bR expression; AVP stimulation of whole islets vs. purified β cells with V1bR, GLP-1R, and GCGR antagonists; glucagon/insulin secretion assays","pmids":["39217353"],"confidence":"Medium","gaps":["Single lab","In vivo physiological relevance of the islet circuit not established","Intracellular signaling from V1bR to glucagon release not detailed"]},{"year":null,"claim":"The intracellular G protein coupling and downstream signaling cascade of AVPR1B remains uncharacterized in the available corpus across its endocrine, behavioral, and metabolic contexts.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of receptor-ligand engagement","G protein/second messenger coupling not resolved beyond Ca2+ observations","Unifying mechanism across tissues not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[1,5]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,5]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,5]}],"complexes":[],"partners":[],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P47901","full_name":"Vasopressin V1b receptor","aliases":["AVPR V1b","AVPR V3","Antidiuretic hormone receptor 1b","Vasopressin V3 receptor"],"length_aa":424,"mass_kda":47.0,"function":"Receptor for arginine vasopressin. The activity of this receptor is mediated by G proteins which activate a phosphatidyl-inositol-calcium second messenger system (Microbial infection) During SARS coronavirus-2/SARS-CoV-2 infection, may recognize and internalize the complex formed by AVP/Arg-vasopressin, SARS-CoV-2 spike protein and secreted ACE2 through DNM2/dynamin 2-dependent endocytosis","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/P47901/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/AVPR1B","classification":"Not Classified","n_dependent_lines":6,"n_total_lines":1208,"dependency_fraction":0.004966887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/AVPR1B","total_profiled":1310},"omim":[{"mim_id":"600821","title":"ARGININE VASOPRESSIN RECEPTOR 1A; AVPR1A","url":"https://www.omim.org/entry/600821"},{"mim_id":"600264","title":"ARGININE VASOPRESSIN RECEPTOR 1B; AVPR1B","url":"https://www.omim.org/entry/600264"},{"mim_id":"219080","title":"ACTH-INDEPENDENT MACRONODULAR ADRENAL HYPERPLASIA 1; AIMAH1","url":"https://www.omim.org/entry/219080"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in single","driving_tissues":[{"tissue":"pituitary gland","ntpm":13.8}],"url":"https://www.proteinatlas.org/search/AVPR1B"},"hgnc":{"alias_symbol":["V1bR","VPR3"],"prev_symbol":["AVPR3"]},"alphafold":{"accession":"P47901","domains":[{"cath_id":"1.20.1070.10","chopping":"32-240_273-350","consensus_level":"high","plddt":88.7963,"start":32,"end":350}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P47901","model_url":"https://alphafold.ebi.ac.uk/files/AF-P47901-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P47901-F1-predicted_aligned_error_v6.png","plddt_mean":73.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=AVPR1B","jax_strain_url":"https://www.jax.org/strain/search?query=AVPR1B"},"sequence":{"accession":"P47901","fasta_url":"https://rest.uniprot.org/uniprotkb/P47901.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P47901/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P47901"}},"corpus_meta":[{"pmid":"20828336","id":"PMC_20828336","title":"The vasopressin Avpr1b receptor: molecular and pharmacological studies.","date":"2010","source":"Stress (Amsterdam, Netherlands)","url":"https://pubmed.ncbi.nlm.nih.gov/20828336","citation_count":87,"is_preprint":false},{"pmid":"18384079","id":"PMC_18384079","title":"Combined effects of exonic polymorphisms in CRHR1 and AVPR1B genes in a case/control study for panic disorder.","date":"2008","source":"American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18384079","citation_count":82,"is_preprint":false},{"pmid":"17909131","id":"PMC_17909131","title":"Evidence of an association between the vasopressin V1b receptor gene (AVPR1B) and childhood-onset mood disorders.","date":"2007","source":"Archives of general psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/17909131","citation_count":63,"is_preprint":false},{"pmid":"23884782","id":"PMC_23884782","title":"A cellular and molecular basis for the selective desmopressin-induced ACTH release in Cushing disease patients: key role of AVPR1b receptor and potential therapeutic implications.","date":"2013","source":"The Journal of clinical endocrinology and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/23884782","citation_count":58,"is_preprint":false},{"pmid":"27920663","id":"PMC_27920663","title":"ASD and Genetic Associations with Receptors for Oxytocin and Vasopressin-AVPR1A, AVPR1B, and OXTR.","date":"2016","source":"Frontiers in neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/27920663","citation_count":43,"is_preprint":false},{"pmid":"23422793","id":"PMC_23422793","title":"Family-based study of AVPR1B association and interaction with stressful life events on depression and anxiety in suicide attempts.","date":"2013","source":"Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/23422793","citation_count":25,"is_preprint":false},{"pmid":"18508119","id":"PMC_18508119","title":"Dissociation of the anxiolytic-like effects of Avpr1a and Avpr1b receptor antagonists in the dorsal and ventral hippocampus.","date":"2008","source":"Neuropeptides","url":"https://pubmed.ncbi.nlm.nih.gov/18508119","citation_count":24,"is_preprint":false},{"pmid":"20846299","id":"PMC_20846299","title":"Attenuated stress response to acute restraint and forced swimming stress in arginine vasopressin 1b receptor subtype (Avpr1b) receptor knockout mice and wild-type mice treated with a novel Avpr1b receptor antagonist.","date":"2010","source":"Journal of neuroendocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/20846299","citation_count":23,"is_preprint":false},{"pmid":"19492333","id":"PMC_19492333","title":"Cloning and expression of the gene for an insect haemocyte anti-aggregation protein (VPr3), from the venom of the endoparasitic wasp, Pimpla hypochondriaca.","date":"2009","source":"Archives of insect biochemistry and physiology","url":"https://pubmed.ncbi.nlm.nih.gov/19492333","citation_count":18,"is_preprint":false},{"pmid":"23580725","id":"PMC_23580725","title":"The effect of vasopressin 1b receptor (V1bR) blockade on HPA axis activity in rats exposed to acute heat stress.","date":"2013","source":"The Journal of experimental biology","url":"https://pubmed.ncbi.nlm.nih.gov/23580725","citation_count":17,"is_preprint":false},{"pmid":"22341483","id":"PMC_22341483","title":"Association between functional polymorphism of the AVPR1b gene and polymorphism rs1293651 of the CRHR1 gene and bipolar disorder with psychotic features.","date":"2012","source":"Journal of affective disorders","url":"https://pubmed.ncbi.nlm.nih.gov/22341483","citation_count":16,"is_preprint":false},{"pmid":"35451730","id":"PMC_35451730","title":"Responsiveness to DDAVP in Cushing's disease is associated with USP8 mutations through enhancing AVPR1B promoter activity.","date":"2022","source":"Pituitary","url":"https://pubmed.ncbi.nlm.nih.gov/35451730","citation_count":16,"is_preprint":false},{"pmid":"23962971","id":"PMC_23962971","title":"Epistatic interaction between CRHR1 and AVPR1b variants as a predictor of major depressive disorder.","date":"2013","source":"Psychiatric 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to polycystic ovary syndrome.","date":"2024","source":"Journal of ovarian research","url":"https://pubmed.ncbi.nlm.nih.gov/39501331","citation_count":3,"is_preprint":false},{"pmid":"36367618","id":"PMC_36367618","title":"Correlation Between Sleep Electroencephalogram, Brain-Derived Neurotrophic Factor, AVPR1B Gene Polymorphism, and Suicidal Behavior in Patients with Depression.","date":"2022","source":"Applied biochemistry and biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/36367618","citation_count":2,"is_preprint":false},{"pmid":"39217353","id":"PMC_39217353","title":"V1bR enhances glucose-stimulated insulin secretion by paracrine production of glucagon which activates GLP-1 receptor.","date":"2024","source":"Cell & bioscience","url":"https://pubmed.ncbi.nlm.nih.gov/39217353","citation_count":2,"is_preprint":false},{"pmid":"42047756","id":"PMC_42047756","title":"Arginine-vasopressin systems in autistic phenotype schizophrenia: effect of a genetic variant of AVPR1a and 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Desmopressin triggered Ca2+ kinetics, ACTH expression/release, and proliferative responses in corticotropinoma primary cultures; an AVPR1B-selective antagonist completely blocked these effects. AVPR1B expression levels in corticotropinomas were dramatically elevated and positively correlated with plasma ACTH levels.\",\n      \"method\": \"Primary cultures of human corticotropinomas and other pituitary adenomas treated with desmopressin ± selective AVPR1B antagonist; [Ca2+]i kinetics, ACTH secretion/expression assays, quantitative RT-PCR of AVPR expression\",\n      \"journal\": \"The Journal of clinical endocrinology and metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Ca2+ imaging, ACTH secretion assay, receptor antagonist blockade, qRT-PCR) in primary human tissue; mechanistic claim directly supported by pharmacological rescue\",\n      \"pmids\": [\"23884782\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Avpr1b on anterior pituitary corticotrophs mediates AVP-stimulated ACTH release in response to acute stress. Both genetic knockout of Avpr1b and pharmacological blockade with a novel Avpr1b antagonist significantly reduced plasma ACTH increases following acute restraint and forced swimming stress. Plasma corticosterone was also reduced in male (but not female) knockout or antagonist-treated mice under restraint stress.\",\n      \"method\": \"Avpr1b knockout mice vs. wild-type; selective Avpr1b antagonist administration; plasma ACTH and corticosterone measurements after acute stress\",\n      \"journal\": \"Journal of neuroendocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO corroborated by pharmacological antagonism with two orthogonal approaches across multiple stress paradigms\",\n      \"pmids\": [\"20846299\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"V1bR (AVPR1B) blockade with the selective antagonist Nelivaptan negatively affected the increase in blood ACTH caused by acute heat stress in rats, directly confirming the positive role of AVP in regulating ACTH secretion from the pituitary via V1bR. Circulating AVP was found to influence intrapituitary V1bR levels under heat stress conditions.\",\n      \"method\": \"Rat heat-stress model; Nelivaptan (selective V1bR antagonist) treatment; plasma ACTH/corticosterone by ELISA/chemiluminescence; intrapituitary V1bR and ACTH by western blot\",\n      \"journal\": \"The Journal of experimental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological blockade with functional hormone readouts, single lab, two orthogonal protein-level endpoints\",\n      \"pmids\": [\"23580725\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Avpr1b in the dorsal hippocampus, but not the ventral hippocampus, mediates anxiety-related behavior in rats. Microinfusion of a selective Avpr1b antagonist (SSR 149415) into the dorsal hippocampus reduced anxiety-like behavior in the elevated plus-maze, whereas the same treatment in the ventral hippocampus had no effect. Neither antagonist reduced anxiety in the shock-probe burying test, indicating response specificity.\",\n      \"method\": \"Stereotaxic microinfusion of selective Avpr1b antagonist (SSR 149415) into dorsal or ventral hippocampus of rats; elevated plus-maze and shock-probe burying behavioral tests\",\n      \"journal\": \"Neuropeptides\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site-specific pharmacological antagonism with behavioral dissociation, single lab\",\n      \"pmids\": [\"18508119\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"USP8 mutations in corticotropinoma cells upregulate AVPR1B promoter activity, thereby increasing AVPR1B expression and enhancing ACTH responsiveness to desmopressin (DDAVP) stimulation in Cushing's disease. DDAVP responsiveness correlated with AVPR1B (but not AVPR2) expression levels, and overexpression of mutant USP8 enhanced Avpr1b promoter activity compared to wild-type USP8.\",\n      \"method\": \"qRT-PCR and immunohistochemistry of AVP receptor expression in 47 Cushing's disease tumor samples; dual-luciferase reporter assay of AVPR1B promoter activity with mutant vs. wild-type USP8 overexpression\",\n      \"journal\": \"Pituitary\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — luciferase reporter assay plus clinical correlation, single lab, two orthogonal methods\",\n      \"pmids\": [\"35451730\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"V1bR (AVPR1B) is expressed exclusively in pancreatic α cells (not β cells). AVP activates V1bR on α cells to stimulate glucagon secretion, and the secreted glucagon then promotes glucose-dependent insulin secretion from β cells in a paracrine manner by activating GLP-1R (but not GCGR) on β cells. AVP-induced insulin secretion from whole islets (but not isolated β cells) was blocked by a V1bR-selective antagonist.\",\n      \"method\": \"Single-cell transcriptome analysis of islet cell V1bR expression; AVP stimulation of isolated islets vs. purified β cells; V1bR-selective antagonist blockade; glucagon secretion assay; GLP-1R and GCGR antagonist experiments\",\n      \"journal\": \"Cell & bioscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (scRNA-seq, pharmacological blockade, receptor-specific antagonists), single lab\",\n      \"pmids\": [\"39217353\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"AVPR1B (V1bR) is a G protein-coupled receptor expressed on anterior pituitary corticotrophs and pancreatic α cells that: (1) mediates AVP-stimulated ACTH release in response to acute stress via HPA axis signaling, with genetic knockout or pharmacological antagonism reducing stress-induced ACTH and corticosterone; (2) drives desmopressin-induced ACTH hypersecretion in Cushing's disease corticotropinomas, where its promoter is upregulated by USP8 mutations; (3) mediates a paracrine α-to-β cell crosstalk in pancreatic islets whereby AVP/V1bR-stimulated glucagon secretion promotes glucose-dependent insulin release via GLP-1R; and (4) in the dorsal hippocampus, modulates anxiety-related behavior, with subregion-specific pharmacological dissociation from the Avpr1a subtype.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"AVPR1B (V1bR) is a vasopressin-responsive G protein-coupled receptor that couples AVP signaling to neuroendocrine, behavioral, and metabolic outputs [#1, #5]. On anterior pituitary corticotrophs it mediates AVP-stimulated ACTH release during acute stress, since genetic knockout and selective pharmacological antagonism both blunt stress-induced ACTH and corticosterone responses [#1], an effect confirmed across additional stress paradigms and species by antagonist blockade [#2]. In Cushing's disease corticotropinomas, AVPR1B is dramatically overexpressed and drives desmopressin-induced ACTH hypersecretion and proliferative/Ca2+ responses that are abolished by an AVPR1B-selective antagonist, with receptor levels correlating with plasma ACTH [#0]; this overexpression is driven by USP8 mutations that upregulate AVPR1B promoter activity [#4]. Beyond the HPA axis, AVPR1B is expressed exclusively in pancreatic \\u03b1 cells, where AVP-stimulated glucagon secretion promotes glucose-dependent insulin release from \\u03b2 cells via paracrine GLP-1R signaling [#5], and in the dorsal hippocampus it modulates anxiety-related behavior in a subregion-specific manner [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established that AVPR1B has a central behavioral role beyond endocrine signaling, anatomically localized to the dorsal hippocampus.\",\n      \"evidence\": \"Site-specific microinfusion of selective Avpr1b antagonist into dorsal vs. ventral hippocampus with elevated plus-maze and shock-probe behavioral tests in rats\",\n      \"pmids\": [\"18508119\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single lab pharmacological study\", \"Downstream circuit and signaling mechanism in hippocampus not defined\", \"Endogenous AVP source driving the response not identified\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstrated by genetic and pharmacological convergence that pituitary Avpr1b is required for AVP-driven ACTH release during acute stress, defining its core HPA-axis function.\",\n      \"evidence\": \"Avpr1b knockout mice and selective antagonist treatment with plasma ACTH/corticosterone measurement after restraint and swim stress\",\n      \"pmids\": [\"20846299\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Sex-dependent corticosterone effect not mechanistically explained\", \"Intracellular signaling coupling not resolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified AVPR1B as the receptor underlying aberrant desmopressin-induced ACTH secretion specifically in corticotropinomas, linking receptor overexpression to disease.\",\n      \"evidence\": \"Primary cultures of human corticotropinomas and other adenomas with desmopressin \\u00b1 selective antagonist; Ca2+ imaging, ACTH secretion/expression, qRT-PCR\",\n      \"pmids\": [\"23884782\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Cause of receptor overexpression not yet established at this stage\", \"Link between Ca2+ signaling and proliferation not detailed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Confirmed across species and stress modality that V1bR antagonism blunts ACTH, reinforcing AVP's positive regulation of pituitary ACTH.\",\n      \"evidence\": \"Rat heat-stress model with Nelivaptan; plasma ACTH/corticosterone and intrapituitary V1bR/ACTH by western blot\",\n      \"pmids\": [\"23580725\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single lab\", \"Regulation of intrapituitary V1bR levels by circulating AVP not mechanistically dissected\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Connected AVPR1B overexpression in Cushing's disease to a transcriptional driver, showing USP8 mutations upregulate the AVPR1B promoter.\",\n      \"evidence\": \"qRT-PCR/IHC of AVP receptors in 47 Cushing's disease tumors plus dual-luciferase AVPR1B promoter assay with mutant vs. wild-type USP8\",\n      \"pmids\": [\"35451730\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Mechanism by which mutant USP8 activates the promoter not defined\", \"Single lab\", \"Selectivity of effect on AVPR1B vs. AVPR2 not fully resolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended AVPR1B function to metabolic regulation, defining an \\u03b1-cell-restricted receptor that orchestrates paracrine \\u03b1-to-\\u03b2 cell crosstalk.\",\n      \"evidence\": \"Single-cell transcriptomics of islet V1bR expression; AVP stimulation of whole islets vs. purified \\u03b2 cells with V1bR, GLP-1R, and GCGR antagonists; glucagon/insulin secretion assays\",\n      \"pmids\": [\"39217353\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single lab\", \"In vivo physiological relevance of the islet circuit not established\", \"Intracellular signaling from V1bR to glucagon release not detailed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The intracellular G protein coupling and downstream signaling cascade of AVPR1B remains uncharacterized in the available corpus across its endocrine, behavioral, and metabolic contexts.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No structural model of receptor-ligand engagement\", \"G protein/second messenger coupling not resolved beyond Ca2+ observations\", \"Unifying mechanism across tissues not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [1, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 5]}\n    ],\n    \"complexes\": [],\n    \"partners\": [],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}