{"gene":"ERFE","run_date":"2026-04-28T17:46:03","timeline":{"discoveries":[{"year":2019,"finding":"ERFE functions as a secreted BMP antagonist that suppresses hepcidin by interfering with the binding of specific BMP ligands to their receptors; the conserved C1q domain is not required for this BMP-inhibitory activity, and inhibition occurs at the extracellular level through direct interaction of ERFE with BMP ligands.","method":"Gain-of-function screen in Xenopus embryos, ectodermal explant assays, ERFE knockdown (morpholino), domain deletion analysis","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (gain-of-function, loss-of-function, domain mutants) in a well-established in vivo system; consistent with parallel findings reported in the Blood commentary (PMID:30287465)","pmids":["31846624","30287465"],"is_preprint":false},{"year":2019,"finding":"The ERFE-A260S variant leads to elevated ERFE protein levels and impairs iron regulation at the hepatic level by disrupting the BMP/SMAD signaling pathway, acting as a genetic modifier of iron overload severity in congenital dyserythropoietic anemia type II.","method":"Functional characterization of ERFE-A260S variant in hepatic cell system; BMP/SMAD pathway readouts (Western blot, reporter assays); patient genotype-phenotype correlation","journal":"American journal of hematology","confidence":"Medium","confidence_rationale":"Tier 2-3 — cell-based functional assay with pathway readout, single lab study","pmids":["31400017"],"is_preprint":false},{"year":2018,"finding":"EPO suppresses BMP-mediated signaling through an ERFE-dependent mechanism, and ERFE in turn interferes with the binding of a specific set of BMPs to their receptors, thereby decreasing hepcidin expression.","method":"Commentary/synthesis of experimental evidence (epistasis: EPO→ERFE→BMP receptor binding interference→hepcidin suppression); referenced primary work by Arezes et al.","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 — pathway position established by epistasis in referenced primary experiments; single commentary paper in this corpus","pmids":["30287465"],"is_preprint":false},{"year":2023,"finding":"In metabolic syndrome rats, ERFE expression in the spleen is regulated downstream of the EPO/STAT5 signaling pathway; activation of EPO/STAT5/ERFE signaling suppresses hepcidin via inhibition of the BMP/SMAD pathway in the liver.","method":"In vivo rat model (metabolic syndrome + chronic intermittent hypobaric hypoxia); protein expression (Western blot for JAK2, STAT3, STAT5, BMP6, SMAD1, hepcidin); mRNA analysis of ERFE and hepcidin","journal":"Journal of trace elements in medicine and biology","confidence":"Medium","confidence_rationale":"Tier 2-3 — in vivo pathway placement with multiple protein readouts; single lab, single model organism","pmids":["37413927"],"is_preprint":false},{"year":2025,"finding":"METTL14 stabilizes ERFE mRNA through IGF2BP3-dependent m6A modification in renal tubular epithelial cells, and this ERFE upregulation promotes ferroptosis during cisplatin-induced kidney injury; knockdown of ERFE attenuates cisplatin-induced ferroptosis.","method":"MeRIP-PCR (m6A modification on ERFE mRNA); RIP assay (METTL14/IGF2BP3-ERFE binding); Actinomycin D mRNA stability assay; siRNA knockdown; CCK-8 viability assay; ferroptosis marker measurement","journal":"Journal of trace elements in medicine and biology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods (MeRIP, RIP, mRNA stability, KD rescue) in a single lab study","pmids":["41205320"],"is_preprint":false},{"year":2024,"finding":"Osteocytes are a novel source of ERFE that contributes to systemic ERFE levels and hepcidin suppression during stress erythropoiesis; EPO receptor signaling in osteocytes is required for this effect, as mice lacking EPO receptors specifically in osteocytes (Epor flox/flox × Dmp1-Cre) show reduced hepcidin suppression after phlebotomy.","method":"Bulk RNAseq of isolated osteocytes; bone marrow transplant in Erfe-/- mice (genetic rescue); conditional knockout (Epor flox/flox × Dmp1-Cre); phlebotomy stress model; serum hepcidin measurement","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — two complementary genetic mouse models with direct functional readout; preprint, not yet peer-reviewed","pmids":["bio_10.1101_2024.09.27.615409"],"is_preprint":true}],"current_model":"ERFE (erythroferrone/FAM132b) is a secreted C1q/TNF-related protein produced primarily by erythroblasts (and also osteocytes) in response to EPO/STAT5 signaling; it suppresses hepatic hepcidin expression by acting as an extracellular BMP antagonist that directly binds BMP ligands and prevents their engagement with BMP receptors, thereby de-repressing iron absorption, with ERFE mRNA stability itself subject to regulation by METTL14-mediated m6A modification via IGF2BP3."},"narrative":{"teleology":[{"year":2018,"claim":"Establishing the epistatic position of ERFE between EPO signaling and BMP-receptor-mediated hepcidin induction resolved how erythropoietic demand communicates with the hepatic iron-sensing pathway.","evidence":"Synthesis of epistasis experiments (EPO→ERFE→BMP receptor binding interference→hepcidin suppression) referencing primary work by Arezes et al.","pmids":["30287465"],"confidence":"Medium","gaps":["Direct binding between ERFE and specific BMP ligands not yet demonstrated at this stage","Structural basis for ERFE–BMP interaction unknown"]},{"year":2019,"claim":"Demonstrating that ERFE directly interferes with BMP ligand–receptor binding at the extracellular level — and that the C1q domain is dispensable — established the molecular mechanism of hepcidin suppression and narrowed the active region of ERFE.","evidence":"Gain-of-function screen and ectodermal explant assays in Xenopus embryos; ERFE morpholino knockdown; domain deletion constructs","pmids":["31846624","30287465"],"confidence":"High","gaps":["Identity of the minimal BMP-binding domain within ERFE not defined","No structural model of ERFE–BMP complex","Selectivity for individual BMP ligands (BMP2/6/etc.) not quantified biochemically"]},{"year":2019,"claim":"Identification of the ERFE-A260S variant as a functional modifier of BMP/SMAD signaling linked ERFE genetic variation to clinical iron overload in congenital dyserythropoietic anemia type II.","evidence":"Functional characterization of A260S variant in hepatic cells using BMP/SMAD reporter assays and Western blot; genotype–phenotype correlation in patients","pmids":["31400017"],"confidence":"Medium","gaps":["Mechanism by which A260S increases ERFE protein levels not determined","Replication in independent patient cohorts not reported","Effect size relative to other iron-overload modifiers not compared"]},{"year":2023,"claim":"In vivo confirmation that EPO/STAT5 signaling induces ERFE, which in turn suppresses BMP/SMAD-dependent hepcidin in the liver, validated the EPO→STAT5→ERFE→BMP/SMAD→hepcidin axis in a mammalian physiological context.","evidence":"Metabolic syndrome rat model with chronic intermittent hypobaric hypoxia; Western blot for JAK2, STAT3, STAT5, BMP6, SMAD1, hepcidin; mRNA analysis","pmids":["37413927"],"confidence":"Medium","gaps":["Single disease model (metabolic syndrome); generalizability to other erythropoietic stress states not tested","STAT5 direct binding to ERFE promoter not shown in this study"]},{"year":2025,"claim":"Discovery that METTL14-mediated m6A modification stabilizes ERFE mRNA via IGF2BP3 revealed an epitranscriptomic layer of ERFE regulation and an unexpected role for ERFE in promoting ferroptosis in renal tubular cells.","evidence":"MeRIP-PCR, RIP assay for METTL14/IGF2BP3–ERFE mRNA binding, actinomycin D stability assay, siRNA knockdown with ferroptosis marker measurement in cisplatin-treated renal epithelial cells","pmids":["41205320"],"confidence":"Medium","gaps":["Single cell type and injury model (cisplatin nephrotoxicity); relevance to erythropoietic tissues unknown","Whether m6A regulation of ERFE operates during physiological stress erythropoiesis not tested","Downstream mechanism by which ERFE promotes ferroptosis not elucidated"]},{"year":null,"claim":"The structural basis for ERFE–BMP ligand selectivity, the minimal active domain of ERFE, and the physiological contribution of non-erythroblast ERFE sources (e.g., osteocytes) to systemic iron homeostasis remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No crystal or cryo-EM structure of ERFE or ERFE–BMP complex","Quantitative contribution of osteocyte-derived versus erythroblast-derived ERFE to hepcidin regulation in vivo not established in peer-reviewed literature","Whether ERFE-mediated ferroptosis in kidney has pathological relevance beyond cisplatin injury is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,2]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[0,2]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,2,3]}],"complexes":[],"partners":["BMP2","BMP6","IGF2BP3","METTL14"],"other_free_text":[]},"mechanistic_narrative":"ERFE (erythroferrone) is a secreted BMP antagonist that suppresses hepatic hepcidin expression by directly binding BMP ligands in the extracellular space and preventing their engagement with BMP receptors, thereby de-repressing iron absorption and mobilization [PMID:31846624, PMID:30287465]. ERFE is produced by erythroblasts (and osteocytes) downstream of EPO/STAT5 signaling, establishing a hormonal link between erythropoietic drive and iron supply [PMID:37413927, PMID:30287465]. The BMP-inhibitory activity resides outside the conserved C1q domain, and a missense variant (A260S) that elevates ERFE levels acts as a genetic modifier of iron overload severity in congenital dyserythropoietic anemia type II [PMID:31846624, PMID:31400017]."},"prefetch_data":{"uniprot":{"accession":"Q4G0M1","full_name":"Erythroferrone","aliases":["Complement C1q tumor necrosis factor-related protein 15","Myonectin"],"length_aa":354,"mass_kda":37.3,"function":"Iron-regulatory hormone that acts as an erythroid regulator after hemorrhage: produced by erythroblasts following blood loss and mediates suppression of hepcidin (HAMP) expression in the liver, thereby promoting increased iron absorption and mobilization from stores (PubMed:24880340, PubMed:30097509, PubMed:31800957). Promotes lipid uptake into adipocytes and hepatocytes via transcriptional up-regulation of genes involved in fatty acid uptake (By similarity). Inhibits apoptosis and inflammatory response in cardiomyocytes via promotion of sphingosine-1-phosphate (S1P) and cAMP-dependent activation of AKT signaling (By similarity). Inhibits autophagy induced by nutrient deficiency in hepatocytes via promoting the phosphorylation of IRS1, AKT, and MTOR, and thereby subsequent activation of the AKT-MTOR signaling pathway (By similarity). Negatively regulates the differentiation of osteoblasts, potentially via sequestering BMP2, and thereby inhibits the activation of SMAD signaling (By similarity). The reduction in BMP2 signaling in osteoblasts also results in an increase in expression of the osteoclastogenesis-promoting factors TNFSF11/RANKL and SOST, thereby indirectly promotes bone resorption (By similarity)","subcellular_location":"Secreted","url":"https://www.uniprot.org/uniprotkb/Q4G0M1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ERFE","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":77,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ERFE","total_profiled":1310},"omim":[{"mim_id":"615099","title":"ERYTHROFERRONE; ERFE","url":"https://www.omim.org/entry/615099"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"skeletal muscle","ntpm":14.1},{"tissue":"testis","ntpm":12.4},{"tissue":"thyroid gland","ntpm":23.1}],"url":"https://www.proteinatlas.org/search/ERFE"},"hgnc":{"alias_symbol":["FLJ37034","CTRP15","C1QTNF15"],"prev_symbol":["FAM132B"]},"alphafold":{"accession":"Q4G0M1","domains":[{"cath_id":"2.60.120.40","chopping":"206-354","consensus_level":"high","plddt":90.3309,"start":206,"end":354}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q4G0M1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q4G0M1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q4G0M1-F1-predicted_aligned_error_v6.png","plddt_mean":69.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ERFE","jax_strain_url":"https://www.jax.org/strain/search?query=ERFE"},"sequence":{"accession":"Q4G0M1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q4G0M1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q4G0M1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q4G0M1"}},"corpus_meta":[{"pmid":"22351773","id":"PMC_22351773","title":"Myonectin (CTRP15), a novel myokine that links skeletal muscle to systemic lipid homeostasis.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22351773","citation_count":304,"is_preprint":false},{"pmid":"31400017","id":"PMC_31400017","title":"The BMP-SMAD pathway mediates the impaired hepatic iron metabolism associated with the ERFE-A260S variant.","date":"2019","source":"American journal of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/31400017","citation_count":23,"is_preprint":false},{"pmid":"32424654","id":"PMC_32424654","title":"CTRP15 derived from cardiac myocytes attenuates TGFβ1-induced fibrotic response in cardiac fibroblasts.","date":"2020","source":"Cardiovascular drugs and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/32424654","citation_count":16,"is_preprint":false},{"pmid":"35286626","id":"PMC_35286626","title":"CTRP15 promotes macrophage cholesterol efflux and attenuates atherosclerosis by increasing the expression of ABCA1.","date":"2022","source":"Journal of physiology and biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/35286626","citation_count":12,"is_preprint":false},{"pmid":"40036737","id":"PMC_40036737","title":"Interplay between iron metabolism, inflammation, and EPO-ERFE-hepcidin axis in RDEB-associated chronic anemia.","date":"2025","source":"Blood advances","url":"https://pubmed.ncbi.nlm.nih.gov/40036737","citation_count":7,"is_preprint":false},{"pmid":"30287465","id":"PMC_30287465","title":"A long sought after \"receptor\" for ERFE?","date":"2018","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/30287465","citation_count":6,"is_preprint":false},{"pmid":"38726186","id":"PMC_38726186","title":"Combined serum CTRP7 and CTRP15 levels as a novel biomarker for insulin resistance and type 2 diabetes mellitus.","date":"2024","source":"Heliyon","url":"https://pubmed.ncbi.nlm.nih.gov/38726186","citation_count":5,"is_preprint":false},{"pmid":"31846624","id":"PMC_31846624","title":"The secreted BMP antagonist ERFE is required for the development of a functional circulatory system in Xenopus.","date":"2019","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/31846624","citation_count":5,"is_preprint":false},{"pmid":"35463985","id":"PMC_35463985","title":"Effects of Different Ovulation Induction Regimens on Sex Hormone Levels and Serum CTRP3 and CTRP15 Levels in Patients with Polycystic Ovary Syndrome (PCOS).","date":"2022","source":"BioMed research international","url":"https://pubmed.ncbi.nlm.nih.gov/35463985","citation_count":4,"is_preprint":false},{"pmid":"37413927","id":"PMC_37413927","title":"Chronic intermittent hypobaric hypoxia improves iron metabolism disorders via the IL-6/JAK2/STAT3 and Epo/STAT5/ERFE signaling pathways in metabolic syndrome rats.","date":"2023","source":"Journal of trace elements in medicine and biology : organ of the Society for Minerals and Trace Elements (GMS)","url":"https://pubmed.ncbi.nlm.nih.gov/37413927","citation_count":4,"is_preprint":false},{"pmid":"34900801","id":"PMC_34900801","title":"Increased circulating level of CTRP15 in patients with type 2 diabetes mellitus and its relation with inflammation and insulin resistance.","date":"2021","source":"Journal of diabetes and metabolic disorders","url":"https://pubmed.ncbi.nlm.nih.gov/34900801","citation_count":3,"is_preprint":false},{"pmid":"35922561","id":"PMC_35922561","title":"Codon-optimized FAM132b gene therapy prevents dietary obesity by blockading adrenergic response and insulin action.","date":"2022","source":"International journal of obesity (2005)","url":"https://pubmed.ncbi.nlm.nih.gov/35922561","citation_count":2,"is_preprint":false},{"pmid":"41205320","id":"PMC_41205320","title":"METTL14 promotes ferroptosis during the development of cisplatin-induced kidney injury by stabilizing ERFE through IGF2BP3-dependent m6A methylation.","date":"2025","source":"Journal of trace elements in medicine and biology : organ of the Society for Minerals and Trace Elements (GMS)","url":"https://pubmed.ncbi.nlm.nih.gov/41205320","citation_count":0,"is_preprint":false},{"pmid":"41836830","id":"PMC_41836830","title":"Correlation of serum CTRP9 and CTRP15 levels with HOMA-IR and HOMA-B in metabolic syndrome patients with and without coronary artery disease.","date":"2026","source":"Pakistan journal of medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41836830","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.11.03.25339441","title":"<i>Veillonella atypica</i>  supplementation reduces fatigue interference and increases voluntary physical activity: A randomized controlled trial with mechanistic validation in mice","date":"2025-11-06","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.03.25339441","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.09.27.615409","title":"Osteocyte-derived erythroferrone regulates liver hepcidin during stress erythropoiesis","date":"2024-09-30","source":"bioRxiv","url":"https://doi.org/10.1101/2024.09.27.615409","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11050,"output_tokens":1600,"usd":0.028575},"stage2":{"model":"claude-opus-4-6","input_tokens":4855,"output_tokens":1729,"usd":0.10125},"total_usd":0.129825,"stage1_batch_id":"msgbatch_0118RScg3WGaGkaZRtWZbtce","stage2_batch_id":"msgbatch_01Cpfzvtbj42aqp5oYZ5Te2s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2019,\n      \"finding\": \"ERFE functions as a secreted BMP antagonist that suppresses hepcidin by interfering with the binding of specific BMP ligands to their receptors; the conserved C1q domain is not required for this BMP-inhibitory activity, and inhibition occurs at the extracellular level through direct interaction of ERFE with BMP ligands.\",\n      \"method\": \"Gain-of-function screen in Xenopus embryos, ectodermal explant assays, ERFE knockdown (morpholino), domain deletion analysis\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (gain-of-function, loss-of-function, domain mutants) in a well-established in vivo system; consistent with parallel findings reported in the Blood commentary (PMID:30287465)\",\n      \"pmids\": [\"31846624\", \"30287465\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The ERFE-A260S variant leads to elevated ERFE protein levels and impairs iron regulation at the hepatic level by disrupting the BMP/SMAD signaling pathway, acting as a genetic modifier of iron overload severity in congenital dyserythropoietic anemia type II.\",\n      \"method\": \"Functional characterization of ERFE-A260S variant in hepatic cell system; BMP/SMAD pathway readouts (Western blot, reporter assays); patient genotype-phenotype correlation\",\n      \"journal\": \"American journal of hematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — cell-based functional assay with pathway readout, single lab study\",\n      \"pmids\": [\"31400017\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"EPO suppresses BMP-mediated signaling through an ERFE-dependent mechanism, and ERFE in turn interferes with the binding of a specific set of BMPs to their receptors, thereby decreasing hepcidin expression.\",\n      \"method\": \"Commentary/synthesis of experimental evidence (epistasis: EPO→ERFE→BMP receptor binding interference→hepcidin suppression); referenced primary work by Arezes et al.\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pathway position established by epistasis in referenced primary experiments; single commentary paper in this corpus\",\n      \"pmids\": [\"30287465\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In metabolic syndrome rats, ERFE expression in the spleen is regulated downstream of the EPO/STAT5 signaling pathway; activation of EPO/STAT5/ERFE signaling suppresses hepcidin via inhibition of the BMP/SMAD pathway in the liver.\",\n      \"method\": \"In vivo rat model (metabolic syndrome + chronic intermittent hypobaric hypoxia); protein expression (Western blot for JAK2, STAT3, STAT5, BMP6, SMAD1, hepcidin); mRNA analysis of ERFE and hepcidin\",\n      \"journal\": \"Journal of trace elements in medicine and biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — in vivo pathway placement with multiple protein readouts; single lab, single model organism\",\n      \"pmids\": [\"37413927\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"METTL14 stabilizes ERFE mRNA through IGF2BP3-dependent m6A modification in renal tubular epithelial cells, and this ERFE upregulation promotes ferroptosis during cisplatin-induced kidney injury; knockdown of ERFE attenuates cisplatin-induced ferroptosis.\",\n      \"method\": \"MeRIP-PCR (m6A modification on ERFE mRNA); RIP assay (METTL14/IGF2BP3-ERFE binding); Actinomycin D mRNA stability assay; siRNA knockdown; CCK-8 viability assay; ferroptosis marker measurement\",\n      \"journal\": \"Journal of trace elements in medicine and biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (MeRIP, RIP, mRNA stability, KD rescue) in a single lab study\",\n      \"pmids\": [\"41205320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Osteocytes are a novel source of ERFE that contributes to systemic ERFE levels and hepcidin suppression during stress erythropoiesis; EPO receptor signaling in osteocytes is required for this effect, as mice lacking EPO receptors specifically in osteocytes (Epor flox/flox × Dmp1-Cre) show reduced hepcidin suppression after phlebotomy.\",\n      \"method\": \"Bulk RNAseq of isolated osteocytes; bone marrow transplant in Erfe-/- mice (genetic rescue); conditional knockout (Epor flox/flox × Dmp1-Cre); phlebotomy stress model; serum hepcidin measurement\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — two complementary genetic mouse models with direct functional readout; preprint, not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2024.09.27.615409\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"ERFE (erythroferrone/FAM132b) is a secreted C1q/TNF-related protein produced primarily by erythroblasts (and also osteocytes) in response to EPO/STAT5 signaling; it suppresses hepatic hepcidin expression by acting as an extracellular BMP antagonist that directly binds BMP ligands and prevents their engagement with BMP receptors, thereby de-repressing iron absorption, with ERFE mRNA stability itself subject to regulation by METTL14-mediated m6A modification via IGF2BP3.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"ERFE (erythroferrone) is a secreted BMP antagonist that suppresses hepatic hepcidin expression by directly binding BMP ligands in the extracellular space and preventing their engagement with BMP receptors, thereby de-repressing iron absorption and mobilization [PMID:31846624, PMID:30287465]. ERFE is produced by erythroblasts (and osteocytes) downstream of EPO/STAT5 signaling, establishing a hormonal link between erythropoietic drive and iron supply [PMID:37413927, PMID:30287465]. The BMP-inhibitory activity resides outside the conserved C1q domain, and a missense variant (A260S) that elevates ERFE levels acts as a genetic modifier of iron overload severity in congenital dyserythropoietic anemia type II [PMID:31846624, PMID:31400017].\",\n  \"teleology\": [\n    {\n      \"year\": 2018,\n      \"claim\": \"Establishing the epistatic position of ERFE between EPO signaling and BMP-receptor-mediated hepcidin induction resolved how erythropoietic demand communicates with the hepatic iron-sensing pathway.\",\n      \"evidence\": \"Synthesis of epistasis experiments (EPO→ERFE→BMP receptor binding interference→hepcidin suppression) referencing primary work by Arezes et al.\",\n      \"pmids\": [\"30287465\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct binding between ERFE and specific BMP ligands not yet demonstrated at this stage\",\n        \"Structural basis for ERFE–BMP interaction unknown\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrating that ERFE directly interferes with BMP ligand–receptor binding at the extracellular level — and that the C1q domain is dispensable — established the molecular mechanism of hepcidin suppression and narrowed the active region of ERFE.\",\n      \"evidence\": \"Gain-of-function screen and ectodermal explant assays in Xenopus embryos; ERFE morpholino knockdown; domain deletion constructs\",\n      \"pmids\": [\"31846624\", \"30287465\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Identity of the minimal BMP-binding domain within ERFE not defined\",\n        \"No structural model of ERFE–BMP complex\",\n        \"Selectivity for individual BMP ligands (BMP2/6/etc.) not quantified biochemically\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identification of the ERFE-A260S variant as a functional modifier of BMP/SMAD signaling linked ERFE genetic variation to clinical iron overload in congenital dyserythropoietic anemia type II.\",\n      \"evidence\": \"Functional characterization of A260S variant in hepatic cells using BMP/SMAD reporter assays and Western blot; genotype–phenotype correlation in patients\",\n      \"pmids\": [\"31400017\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which A260S increases ERFE protein levels not determined\",\n        \"Replication in independent patient cohorts not reported\",\n        \"Effect size relative to other iron-overload modifiers not compared\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"In vivo confirmation that EPO/STAT5 signaling induces ERFE, which in turn suppresses BMP/SMAD-dependent hepcidin in the liver, validated the EPO→STAT5→ERFE→BMP/SMAD→hepcidin axis in a mammalian physiological context.\",\n      \"evidence\": \"Metabolic syndrome rat model with chronic intermittent hypobaric hypoxia; Western blot for JAK2, STAT3, STAT5, BMP6, SMAD1, hepcidin; mRNA analysis\",\n      \"pmids\": [\"37413927\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single disease model (metabolic syndrome); generalizability to other erythropoietic stress states not tested\",\n        \"STAT5 direct binding to ERFE promoter not shown in this study\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Discovery that METTL14-mediated m6A modification stabilizes ERFE mRNA via IGF2BP3 revealed an epitranscriptomic layer of ERFE regulation and an unexpected role for ERFE in promoting ferroptosis in renal tubular cells.\",\n      \"evidence\": \"MeRIP-PCR, RIP assay for METTL14/IGF2BP3–ERFE mRNA binding, actinomycin D stability assay, siRNA knockdown with ferroptosis marker measurement in cisplatin-treated renal epithelial cells\",\n      \"pmids\": [\"41205320\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single cell type and injury model (cisplatin nephrotoxicity); relevance to erythropoietic tissues unknown\",\n        \"Whether m6A regulation of ERFE operates during physiological stress erythropoiesis not tested\",\n        \"Downstream mechanism by which ERFE promotes ferroptosis not elucidated\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural basis for ERFE–BMP ligand selectivity, the minimal active domain of ERFE, and the physiological contribution of non-erythroblast ERFE sources (e.g., osteocytes) to systemic iron homeostasis remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No crystal or cryo-EM structure of ERFE or ERFE–BMP complex\",\n        \"Quantitative contribution of osteocyte-derived versus erythroblast-derived ERFE to hepcidin regulation in vivo not established in peer-reviewed literature\",\n        \"Whether ERFE-mediated ferroptosis in kidney has pathological relevance beyond cisplatin injury is unknown\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 2, 3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"BMP2\",\n      \"BMP6\",\n      \"IGF2BP3\",\n      \"METTL14\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}