{"gene":"RARRES2","run_date":"2026-04-28T19:45:45","timeline":{"discoveries":[{"year":1997,"finding":"TIG2 (RARRES2) is a retinoid-responsive gene whose expression is up-regulated by the RAR beta/gamma-selective retinoid tazarotene, and this induction requires keratinocytes and fibroblasts to form a 3-dimensional tissue-like structure; RAR-specific (but not RXR-specific) retinoids increase TIG2 mRNA levels.","method":"Subtraction hybridization, Northern blot analysis, skin raft culture system, receptor-selective retinoid treatment","journal":"The Journal of investigative dermatology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (subtraction hybridization, Northern blot, receptor-selective ligands) in original discovery paper","pmids":["9204961"],"is_preprint":false},{"year":2003,"finding":"TIG2/RARRES2 (chemerin) was identified as the natural ligand of the orphan GPCR ChemR23 (CMKLR1); the bioactive circulating form represents amino acid residues 21–154 of the 163-amino-acid prepropeptide.","method":"Reverse pharmacology screening of peptide library from human hemofiltrate; isolation and biochemical characterization","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 1 — biochemical reconstitution identifying natural ligand-receptor pair with defined processed form","pmids":["14675762"],"is_preprint":false},{"year":2004,"finding":"Two processed bioactive forms of TIG2/RARRES2 were isolated from CHO cell supernatant (residues T20–F156 and T20–A155 of the 163-aa propeptide), demonstrating that proteolytic processing of the C-terminus generates active chemerin.","method":"Heparin-affinity and reversed-phase chromatography purification; Edman sequencing; MALDI-TOF-MS","journal":"Journal of chromatography. B","confidence":"High","confidence_rationale":"Tier 1 — direct biochemical characterization of processed protein forms with mass spectrometry and sequencing","pmids":["15522723"],"is_preprint":false},{"year":2014,"finding":"Recombinant RARRES2/chemerin reduces progesterone and estradiol production, cholesterol content, STAR abundance, CYP19A1 and HMGCR protein levels, and MAPK3/1 phosphorylation in bovine granulosa cells, acting through its receptor CMKLR1; it also arrests oocyte meiotic progression at the germinal vesicle stage and inhibits MAPK3/1 phosphorylation in cumulus-oocyte complexes.","method":"In vitro granulosa cell culture with recombinant chemerin; anti-CMKLR1 antibody blockade; immunoblotting; in vitro oocyte maturation assay","journal":"Biology of reproduction","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal assays with receptor blockade confirming CMKLR1 dependence","pmids":["24671882"],"is_preprint":false},{"year":2017,"finding":"RARRES2 overexpression in adrenocortical carcinoma cells promotes β-catenin phosphorylation and degradation (inhibiting Wnt/β-catenin pathway) and inhibits p38 MAPK phosphorylation through an immune-independent, cell-intrinsic mechanism; this suppresses cell proliferation, invasion, and tumor growth in vivo in immunodeficient xenograft models.","method":"RARRES2 overexpression in ACC cell lines; in vitro proliferation/invasion assays; immunodeficient mouse xenograft models; immunoblotting for β-catenin phosphorylation and p38","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (in vitro + in vivo xenograft) with defined signaling readouts","pmids":["28114280"],"is_preprint":false},{"year":2015,"finding":"RARRES2 expression in MDCK cells increases RSV replication 10–100 fold; siRNA knockdown of RARRES2 in RSV-susceptible HEp-2 and A549 cells reduces RSV replication, establishing RARRES2 as a host cell factor that promotes respiratory syncytial virus replication.","method":"cDNA library transfection into MDCK cells; microarray; siRNA knockdown; viral replication assay","journal":"Virus research","confidence":"Medium","confidence_rationale":"Tier 2 — gain-of-function and loss-of-function with defined viral replication readout, single lab","pmids":["26277777"],"is_preprint":false},{"year":2023,"finding":"RARRES2 deficiency in brain-metastatic TNBC cells promotes brain metastasis by activating the PTEN–mTOR–SREBP1 signaling axis, increasing glycerophospholipid levels and decreasing triacylglycerols, thereby reprogramming lipid metabolism to facilitate cancer cell survival in the brain microenvironment.","method":"Multi-omics (transcriptomics, lipidomics), RARRES2 knockdown/overexpression in vitro and in vivo, signaling pathway analysis (PTEN/mTOR/SREBP1 immunoblotting)","journal":"Military Medical Research","confidence":"Medium","confidence_rationale":"Tier 2 — multiple omics approaches with in vitro and in vivo validation, single lab","pmids":["37491281"],"is_preprint":false},{"year":2024,"finding":"In osteosarcoma, TAM-secreted IGF-1 promotes RARRES2-mediated stemness maintenance in osteosarcoma stem cells (OSCs); single-cell transcriptomics and in vitro studies identified the IGF-RARRES2 axis as a key intercellular communication node between OSCs and tumor-associated macrophages.","method":"Single-cell RNA sequencing; transcriptome-based cell communication analysis; in vitro co-culture/signaling assays","journal":"Scientific reports","confidence":"Low","confidence_rationale":"Tier 3 — mechanistic pathway proposed via single-cell transcriptomics with limited in vitro functional validation","pmids":["38280909"],"is_preprint":false},{"year":2025,"finding":"During liver fibrosis regression, pericentral hepatocytes secrete Rarres2, which modulates hepatic stellate cell (HSC) function as identified by single-cell fixed RNA profiling of a mouse cirrhosis model.","method":"Single-cell fixed RNA profiling (FLEX) of TAA-induced mouse liver fibrosis model; NicheNet intercellular communication analysis","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3/4 — preprint, computational/transcriptomic identification of secreted signal with limited direct functional validation","pmids":[],"is_preprint":true}],"current_model":"RARRES2 encodes chemerin, a secreted adipokine/chemokine that is transcriptionally induced by RAR-selective retinoids and undergoes C-terminal proteolytic processing to generate bioactive forms that act as the natural ligand for the GPCR ChemR23/CMKLR1, thereby regulating immune cell chemotaxis, granulosa cell steroidogenesis (via CMKLR1-dependent inhibition of MAPK/steroidogenic enzyme signaling), Wnt/β-catenin and p38 MAPK pathways (as a cell-intrinsic tumor suppressor), and lipid metabolic reprogramming via the PTEN–mTOR–SREBP1 axis."},"narrative":{"teleology":[{"year":1997,"claim":"The identification of TIG2/RARRES2 as a retinoid-responsive gene established that RAR-specific signaling transcriptionally controls a previously unknown secreted factor, linking retinoid biology to a novel downstream effector.","evidence":"Subtraction hybridization and Northern blot in skin raft cultures treated with receptor-selective retinoids","pmids":["9204961"],"confidence":"High","gaps":["Protein product function was unknown","Receptor for the gene product had not been identified","Mechanism of RAR-dependent transcriptional regulation not defined"]},{"year":2003,"claim":"Identification of chemerin (RARRES2 product) as the natural ligand of the orphan GPCR ChemR23/CMKLR1 resolved the receptor-ligand pairing and revealed that the bioactive form (residues 21–154) is generated by proteolytic processing of a 163-aa propeptide.","evidence":"Reverse pharmacology screening of hemofiltrate-derived peptides; biochemical characterization of processed forms","pmids":["14675762"],"confidence":"High","gaps":["The specific proteases responsible for C-terminal processing were not identified","Whether additional processed forms exist was unknown","Downstream intracellular signaling cascades activated by ChemR23 were uncharacterized"]},{"year":2004,"claim":"Biochemical isolation of two distinct C-terminally processed bioactive chemerin forms (ending at F156 and A155) demonstrated that multiple cleavage events generate active species, establishing that regulated proteolysis tunes chemerin bioactivity.","evidence":"Heparin-affinity and reversed-phase chromatography purification from CHO supernatant; Edman sequencing and MALDI-TOF-MS","pmids":["15522723"],"confidence":"High","gaps":["Identity of the processing proteases remained unknown","Relative potencies of different processed forms on ChemR23 were not compared","In vivo relevance of each form was not determined"]},{"year":2014,"claim":"Demonstrating that chemerin suppresses progesterone/estradiol production and MAPK3/1 phosphorylation in granulosa cells via CMKLR1 established a CMKLR1-dependent mechanism for chemerin's regulation of reproductive steroidogenesis and oocyte maturation.","evidence":"In vitro granulosa cell and cumulus-oocyte complex cultures with recombinant chemerin; anti-CMKLR1 blocking antibody; immunoblotting","pmids":["24671882"],"confidence":"High","gaps":["In vivo reproductive phenotype of chemerin deficiency was not shown","Whether additional chemerin receptors (GPR1, CCRL2) contribute in ovarian context was not tested","Precise mechanism linking CMKLR1 to STAR/CYP19A1 downregulation was not fully delineated"]},{"year":2015,"claim":"Gain- and loss-of-function experiments showing RARRES2 promotes RSV replication identified chemerin as a host cell factor exploited by respiratory syncytial virus, expanding its functional repertoire beyond chemotaxis and metabolic regulation.","evidence":"cDNA overexpression in MDCK cells and siRNA knockdown in HEp-2/A549 cells with viral replication assays","pmids":["26277777"],"confidence":"Medium","gaps":["Mechanism by which RARRES2 promotes viral replication was not elucidated","Whether the effect requires CMKLR1 signaling or is receptor-independent was not tested","Not independently replicated by other groups"]},{"year":2017,"claim":"Showing that RARRES2 overexpression promotes β-catenin phosphorylation/degradation and inhibits p38 MAPK in adrenocortical carcinoma cells in a cell-intrinsic, immune-independent manner established chemerin as a tumor suppressor acting through Wnt/β-catenin and MAPK pathways.","evidence":"RARRES2 overexpression in ACC cell lines; proliferation/invasion assays; immunodeficient mouse xenograft; immunoblotting","pmids":["28114280"],"confidence":"High","gaps":["Whether the tumor-suppressive activity requires CMKLR1 or another receptor was not determined","Direct molecular target linking chemerin to β-catenin phosphorylation machinery was not identified","Relevance beyond adrenocortical carcinoma was not demonstrated"]},{"year":2023,"claim":"Multi-omics analysis revealing that RARRES2 loss activates PTEN–mTOR–SREBP1 signaling and reprograms lipid metabolism to promote brain metastasis in TNBC established chemerin as a regulator of lipid metabolic adaptation in cancer dissemination.","evidence":"Transcriptomics and lipidomics with RARRES2 knockdown/overexpression in TNBC cells; in vivo brain metastasis models; PTEN/mTOR/SREBP1 immunoblotting","pmids":["37491281"],"confidence":"Medium","gaps":["Direct biochemical link between chemerin and PTEN regulation was not defined","Single laboratory finding without independent replication","Whether the PTEN–mTOR axis operates through CMKLR1 in this context was not addressed"]},{"year":null,"claim":"Key unresolved questions include the identity of the specific proteases that generate bioactive chemerin forms in vivo, the relative contributions of CMKLR1, GPR1, and CCRL2 to chemerin's diverse tissue-specific functions, and the direct molecular mechanism by which chemerin controls β-catenin degradation and PTEN–mTOR signaling.","evidence":"","pmids":[],"confidence":"High","gaps":["In vivo processing proteases not identified","Receptor specificity for tumor-suppressive and metabolic functions not resolved","No structural model of the chemerin–CMKLR1 signaling complex"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[1,3]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[1,2,3]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,3,4]}],"complexes":[],"partners":["CMKLR1"],"other_free_text":[]},"mechanistic_narrative":"RARRES2 encodes chemerin, a secreted chemoattractant protein that functions as the natural ligand for the GPCR ChemR23/CMKLR1, regulating immune cell chemotaxis, steroidogenesis, and tumor-suppressive signaling. Originally identified as a retinoid-responsive gene induced by RAR-selective (but not RXR-selective) retinoids in a skin raft culture system [PMID:9204961], RARRES2 is synthesized as a 163-amino-acid prepropeptide that undergoes C-terminal proteolytic processing to yield bioactive forms (residues 21–154 or 20–155/156) [PMID:14675762, PMID:15522723]. Through CMKLR1, chemerin suppresses steroidogenesis by reducing STAR, CYP19A1, and MAPK3/1 phosphorylation in granulosa cells [PMID:24671882], and acts as a cell-intrinsic tumor suppressor by promoting β-catenin degradation and inhibiting p38 MAPK in adrenocortical carcinoma [PMID:28114280], while its loss in triple-negative breast cancer activates the PTEN–mTOR–SREBP1 axis to reprogram lipid metabolism and promote brain metastasis [PMID:37491281]."},"prefetch_data":{"uniprot":{"accession":"Q99969","full_name":"Retinoic acid receptor responder protein 2","aliases":["Chemerin","RAR-responsive protein TIG2","Tazarotene-induced gene 2 protein"],"length_aa":163,"mass_kda":18.6,"function":"Adipocyte-secreted protein (adipokine) that regulates adipogenesis, metabolism and inflammation through activation of the chemokine-like receptor 1 (CMKLR1). Also acts as a ligand for CMKLR2. Can also bind to C-C chemokine receptor-like 2 (CCRL2), but with a lower affinity than it does to CMKLR1 or CMKLR2 (PubMed:27716822). Positively regulates adipocyte differentiation, modulates the expression of adipocyte genes involved in lipid and glucose metabolism and might play a role in angiogenesis, a process essential for the expansion of white adipose tissue. Also acts as a pro-inflammatory adipokine, causing an increase in secretion of pro-inflammatory and prodiabetic adipokines, which further impair adipose tissue metabolic function and have negative systemic effects including impaired insulin sensitivity, altered glucose and lipid metabolism, and a decrease in vascular function in other tissues. Can have both pro- and anti-inflammatory properties depending on the modality of enzymatic cleavage by different classes of proteases. Acts as a chemotactic factor for leukocyte populations expressing CMKLR1, particularly immature plasmacytoid dendritic cells, but also immature myeloid DCs, macrophages and natural killer cells. Exerts an anti-inflammatory role by preventing TNF/TNFA-induced VCAM1 expression and monocytes adhesion in vascular endothelial cells. The effect is mediated via inhibiting activation of NF-kappa-B and CRK/p38 through stimulation of AKT1/NOS3 signaling and nitric oxide production. Its dual role in inflammation and metabolism might provide a link between chronic inflammation and obesity, as well as obesity-related disorders such as type 2 diabetes and cardiovascular disease. Exhibits an antimicrobial function in the skin","subcellular_location":"Secreted","url":"https://www.uniprot.org/uniprotkb/Q99969/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RARRES2","classification":"Not Classified","n_dependent_lines":5,"n_total_lines":1208,"dependency_fraction":0.0041390728476821195},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/RARRES2","total_profiled":1310},"omim":[{"mim_id":"608379","title":"CHEMOKINE, CC MOTIF, RECEPTOR-LIKE PROTEIN 2; CCRL2","url":"https://www.omim.org/entry/608379"},{"mim_id":"602351","title":"CHEMERIN CHEMOKINE-LIKE RECEPTOR 1; CMKLR1","url":"https://www.omim.org/entry/602351"},{"mim_id":"601973","title":"RETINOIC ACID RECEPTOR RESPONDER 2; RARRES2","url":"https://www.omim.org/entry/601973"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"adrenal gland","ntpm":2645.8},{"tissue":"liver","ntpm":2145.2}],"url":"https://www.proteinatlas.org/search/RARRES2"},"hgnc":{"alias_symbol":["TIG2","HP10433"],"prev_symbol":[]},"alphafold":{"accession":"Q99969","domains":[{"cath_id":"3.10.450.10","chopping":"23-139","consensus_level":"high","plddt":91.8034,"start":23,"end":139}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q99969","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q99969-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q99969-F1-predicted_aligned_error_v6.png","plddt_mean":86.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RARRES2","jax_strain_url":"https://www.jax.org/strain/search?query=RARRES2"},"sequence":{"accession":"Q99969","fasta_url":"https://rest.uniprot.org/uniprotkb/Q99969.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q99969/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q99969"}},"corpus_meta":[{"pmid":"9204961","id":"PMC_9204961","title":"Tazarotene-induced gene 2 (TIG2), a novel retinoid-responsive gene in skin.","date":"1997","source":"The Journal of investigative dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/9204961","citation_count":240,"is_preprint":false},{"pmid":"14675762","id":"PMC_14675762","title":"Characterization of human circulating TIG2 as a ligand for the orphan receptor ChemR23.","date":"2003","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/14675762","citation_count":167,"is_preprint":false},{"pmid":"24671882","id":"PMC_24671882","title":"CHEMERIN (RARRES2) decreases in vitro granulosa cell steroidogenesis and blocks oocyte meiotic progression in bovine species.","date":"2014","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/24671882","citation_count":71,"is_preprint":false},{"pmid":"37491281","id":"PMC_37491281","title":"RARRES2 regulates lipid metabolic reprogramming to mediate the development of brain metastasis in triple negative breast cancer.","date":"2023","source":"Military Medical Research","url":"https://pubmed.ncbi.nlm.nih.gov/37491281","citation_count":52,"is_preprint":false},{"pmid":"19303973","id":"PMC_19303973","title":"RARRES2, encoding the novel adipokine chemerin, is a genetic determinant of disproportionate regional body fat distribution: a comparative magnetic resonance imaging study.","date":"2009","source":"Metabolism: clinical and experimental","url":"https://pubmed.ncbi.nlm.nih.gov/19303973","citation_count":50,"is_preprint":false},{"pmid":"28114280","id":"PMC_28114280","title":"RARRES2 functions as a tumor suppressor by promoting β-catenin phosphorylation/degradation and inhibiting p38 phosphorylation in adrenocortical carcinoma.","date":"2017","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/28114280","citation_count":48,"is_preprint":false},{"pmid":"18955196","id":"PMC_18955196","title":"Downregulation of tazarotene induced gene-2 (TIG2) in skin squamous cell carcinoma.","date":"2008","source":"European journal of dermatology : EJD","url":"https://pubmed.ncbi.nlm.nih.gov/18955196","citation_count":33,"is_preprint":false},{"pmid":"25521368","id":"PMC_25521368","title":"Genome wide meta-analysis highlights the role of genetic variation in RARRES2 in the regulation of circulating serum chemerin.","date":"2014","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/25521368","citation_count":31,"is_preprint":false},{"pmid":"29720894","id":"PMC_29720894","title":"Pleiotropic Associations of RARRES2 Gene Variants and Circulating Chemerin Levels: Potential Roles of Chemerin Involved in the Metabolic and Inflammation-Related Diseases.","date":"2018","source":"Mediators of inflammation","url":"https://pubmed.ncbi.nlm.nih.gov/29720894","citation_count":22,"is_preprint":false},{"pmid":"30866520","id":"PMC_30866520","title":"Circulating Chemerin Levels, but not the RARRES2 Polymorphisms, Predict the Long-Term Outcome of Angiographically Confirmed Coronary Artery Disease.","date":"2019","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/30866520","citation_count":16,"is_preprint":false},{"pmid":"29374087","id":"PMC_29374087","title":"Food restriction but not fish oil increases fertility in hens: role of RARRES2?","date":"2018","source":"Reproduction (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/29374087","citation_count":16,"is_preprint":false},{"pmid":"33058983","id":"PMC_33058983","title":"Variants in the RARRES2 gene are associated with serum chemerin and increase the risk of diabetic kidney disease in type 2 diabetes.","date":"2020","source":"International journal of biological macromolecules","url":"https://pubmed.ncbi.nlm.nih.gov/33058983","citation_count":13,"is_preprint":false},{"pmid":"27446956","id":"PMC_27446956","title":"Association of Polymorphisms in STRA6 and RARRES2 Genes with Type 2 Diabetes in Southern Han Chinese.","date":"2016","source":"BioMed research international","url":"https://pubmed.ncbi.nlm.nih.gov/27446956","citation_count":11,"is_preprint":false},{"pmid":"37246211","id":"PMC_37246211","title":"Targeting copper death genotyping associated gene RARRES2 suppresses glioblastoma progression and macrophages infiltration.","date":"2023","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/37246211","citation_count":9,"is_preprint":false},{"pmid":"30777067","id":"PMC_30777067","title":"Possible involvement of the RARRES2/CMKLR1-system in metabolic and reproductive parameters in Holstein dairy cows.","date":"2019","source":"Reproductive biology and endocrinology : RB&E","url":"https://pubmed.ncbi.nlm.nih.gov/30777067","citation_count":8,"is_preprint":false},{"pmid":"26277777","id":"PMC_26277777","title":"Identification of CCL2, RARRES2 and EFNB2 as host cell factors that influence the multistep replication of respiratory syncytial virus.","date":"2015","source":"Virus research","url":"https://pubmed.ncbi.nlm.nih.gov/26277777","citation_count":7,"is_preprint":false},{"pmid":"22479267","id":"PMC_22479267","title":"Evaluation of Bovine chemerin (RARRES2) Gene Variation on Beef Cattle Production Traits.","date":"2012","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22479267","citation_count":7,"is_preprint":false},{"pmid":"15522723","id":"PMC_15522723","title":"A three-step purification strategy for isolation of hamster TIG2 from CHO cells: characterization of two processed endogenous forms.","date":"2004","source":"Journal of chromatography. B, Analytical technologies in the biomedical and life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/15522723","citation_count":6,"is_preprint":false},{"pmid":"35531645","id":"PMC_35531645","title":"Common variants of RARRES2 and RETN contribute to susceptibility to hand osteoarthritis and related pain.","date":"2022","source":"Biomarkers in medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35531645","citation_count":5,"is_preprint":false},{"pmid":"38280909","id":"PMC_38280909","title":"RARRES2 is involved in the \"lock-and-key\" interactions between osteosarcoma stem cells and tumor-associated macrophages.","date":"2024","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/38280909","citation_count":5,"is_preprint":false},{"pmid":"36385772","id":"PMC_36385772","title":"The transforming growth factor beta ligand TIG-2 modulates the function of neuromuscular junction and muscle energy metabolism in Caenorhabditis elegans.","date":"2022","source":"Frontiers in molecular neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/36385772","citation_count":5,"is_preprint":false},{"pmid":"21687971","id":"PMC_21687971","title":"Exploring polymorphisms of the bovine RARRES2 gene and their associations with growth traits.","date":"2011","source":"Molecular biology reports","url":"https://pubmed.ncbi.nlm.nih.gov/21687971","citation_count":3,"is_preprint":false},{"pmid":"36531488","id":"PMC_36531488","title":"Association of serum levels of Visfatin, Intelectin-1, RARRES2 and their genetic variants with bone mineral density in postmenopausal females.","date":"2022","source":"Frontiers in endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/36531488","citation_count":3,"is_preprint":false},{"pmid":"34336137","id":"PMC_34336137","title":"Hypertension is associated with a variant in the RARRES2 gene in populations of Ouro Preto, Minas Gerais, Brazil: a cross-sectional study.","date":"2021","source":"International journal of molecular epidemiology and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/34336137","citation_count":3,"is_preprint":false},{"pmid":"38000703","id":"PMC_38000703","title":"Association of RARRES2 rs17173608 gene polymorphism and serum Chemerin with acute myocardial infarction and its risk factors: A case-control study in an Iranian population.","date":"2023","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/38000703","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.06.12.657772","title":"A single-cell fixed RNA profiling of liver fibrosis progression and regression reveals SEMA4D and LMCD1 as key mediators of fibrogenesis","date":"2025-06-12","source":"bioRxiv","url":"https://doi.org/10.1101/2025.06.12.657772","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.11.25.625246","title":"Sexual dimorphism of MASLD-driven bone loss","date":"2024-11-28","source":"bioRxiv","url":"https://doi.org/10.1101/2024.11.25.625246","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15715,"output_tokens":2170,"usd":0.039848},"stage2":{"model":"claude-opus-4-6","input_tokens":5493,"output_tokens":4427,"usd":0.20721},"total_usd":0.247058,"stage1_batch_id":"msgbatch_01SUR8NDzVrNmyszWyJeCct7","stage2_batch_id":"msgbatch_01G7Yfutko3cDWzejrwH5AMx","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"TIG2 (RARRES2) is a retinoid-responsive gene whose expression is up-regulated by the RAR beta/gamma-selective retinoid tazarotene, and this induction requires keratinocytes and fibroblasts to form a 3-dimensional tissue-like structure; RAR-specific (but not RXR-specific) retinoids increase TIG2 mRNA levels.\",\n      \"method\": \"Subtraction hybridization, Northern blot analysis, skin raft culture system, receptor-selective retinoid treatment\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (subtraction hybridization, Northern blot, receptor-selective ligands) in original discovery paper\",\n      \"pmids\": [\"9204961\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"TIG2/RARRES2 (chemerin) was identified as the natural ligand of the orphan GPCR ChemR23 (CMKLR1); the bioactive circulating form represents amino acid residues 21–154 of the 163-amino-acid prepropeptide.\",\n      \"method\": \"Reverse pharmacology screening of peptide library from human hemofiltrate; isolation and biochemical characterization\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — biochemical reconstitution identifying natural ligand-receptor pair with defined processed form\",\n      \"pmids\": [\"14675762\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Two processed bioactive forms of TIG2/RARRES2 were isolated from CHO cell supernatant (residues T20–F156 and T20–A155 of the 163-aa propeptide), demonstrating that proteolytic processing of the C-terminus generates active chemerin.\",\n      \"method\": \"Heparin-affinity and reversed-phase chromatography purification; Edman sequencing; MALDI-TOF-MS\",\n      \"journal\": \"Journal of chromatography. B\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct biochemical characterization of processed protein forms with mass spectrometry and sequencing\",\n      \"pmids\": [\"15522723\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Recombinant RARRES2/chemerin reduces progesterone and estradiol production, cholesterol content, STAR abundance, CYP19A1 and HMGCR protein levels, and MAPK3/1 phosphorylation in bovine granulosa cells, acting through its receptor CMKLR1; it also arrests oocyte meiotic progression at the germinal vesicle stage and inhibits MAPK3/1 phosphorylation in cumulus-oocyte complexes.\",\n      \"method\": \"In vitro granulosa cell culture with recombinant chemerin; anti-CMKLR1 antibody blockade; immunoblotting; in vitro oocyte maturation assay\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal assays with receptor blockade confirming CMKLR1 dependence\",\n      \"pmids\": [\"24671882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"RARRES2 overexpression in adrenocortical carcinoma cells promotes β-catenin phosphorylation and degradation (inhibiting Wnt/β-catenin pathway) and inhibits p38 MAPK phosphorylation through an immune-independent, cell-intrinsic mechanism; this suppresses cell proliferation, invasion, and tumor growth in vivo in immunodeficient xenograft models.\",\n      \"method\": \"RARRES2 overexpression in ACC cell lines; in vitro proliferation/invasion assays; immunodeficient mouse xenograft models; immunoblotting for β-catenin phosphorylation and p38\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (in vitro + in vivo xenograft) with defined signaling readouts\",\n      \"pmids\": [\"28114280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"RARRES2 expression in MDCK cells increases RSV replication 10–100 fold; siRNA knockdown of RARRES2 in RSV-susceptible HEp-2 and A549 cells reduces RSV replication, establishing RARRES2 as a host cell factor that promotes respiratory syncytial virus replication.\",\n      \"method\": \"cDNA library transfection into MDCK cells; microarray; siRNA knockdown; viral replication assay\",\n      \"journal\": \"Virus research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — gain-of-function and loss-of-function with defined viral replication readout, single lab\",\n      \"pmids\": [\"26277777\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"RARRES2 deficiency in brain-metastatic TNBC cells promotes brain metastasis by activating the PTEN–mTOR–SREBP1 signaling axis, increasing glycerophospholipid levels and decreasing triacylglycerols, thereby reprogramming lipid metabolism to facilitate cancer cell survival in the brain microenvironment.\",\n      \"method\": \"Multi-omics (transcriptomics, lipidomics), RARRES2 knockdown/overexpression in vitro and in vivo, signaling pathway analysis (PTEN/mTOR/SREBP1 immunoblotting)\",\n      \"journal\": \"Military Medical Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple omics approaches with in vitro and in vivo validation, single lab\",\n      \"pmids\": [\"37491281\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In osteosarcoma, TAM-secreted IGF-1 promotes RARRES2-mediated stemness maintenance in osteosarcoma stem cells (OSCs); single-cell transcriptomics and in vitro studies identified the IGF-RARRES2 axis as a key intercellular communication node between OSCs and tumor-associated macrophages.\",\n      \"method\": \"Single-cell RNA sequencing; transcriptome-based cell communication analysis; in vitro co-culture/signaling assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — mechanistic pathway proposed via single-cell transcriptomics with limited in vitro functional validation\",\n      \"pmids\": [\"38280909\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"During liver fibrosis regression, pericentral hepatocytes secrete Rarres2, which modulates hepatic stellate cell (HSC) function as identified by single-cell fixed RNA profiling of a mouse cirrhosis model.\",\n      \"method\": \"Single-cell fixed RNA profiling (FLEX) of TAA-induced mouse liver fibrosis model; NicheNet intercellular communication analysis\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3/4 — preprint, computational/transcriptomic identification of secreted signal with limited direct functional validation\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"RARRES2 encodes chemerin, a secreted adipokine/chemokine that is transcriptionally induced by RAR-selective retinoids and undergoes C-terminal proteolytic processing to generate bioactive forms that act as the natural ligand for the GPCR ChemR23/CMKLR1, thereby regulating immune cell chemotaxis, granulosa cell steroidogenesis (via CMKLR1-dependent inhibition of MAPK/steroidogenic enzyme signaling), Wnt/β-catenin and p38 MAPK pathways (as a cell-intrinsic tumor suppressor), and lipid metabolic reprogramming via the PTEN–mTOR–SREBP1 axis.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"RARRES2 encodes chemerin, a secreted chemoattractant protein that functions as the natural ligand for the GPCR ChemR23/CMKLR1, regulating immune cell chemotaxis, steroidogenesis, and tumor-suppressive signaling. Originally identified as a retinoid-responsive gene induced by RAR-selective (but not RXR-selective) retinoids in a skin raft culture system [PMID:9204961], RARRES2 is synthesized as a 163-amino-acid prepropeptide that undergoes C-terminal proteolytic processing to yield bioactive forms (residues 21–154 or 20–155/156) [PMID:14675762, PMID:15522723]. Through CMKLR1, chemerin suppresses steroidogenesis by reducing STAR, CYP19A1, and MAPK3/1 phosphorylation in granulosa cells [PMID:24671882], and acts as a cell-intrinsic tumor suppressor by promoting β-catenin degradation and inhibiting p38 MAPK in adrenocortical carcinoma [PMID:28114280], while its loss in triple-negative breast cancer activates the PTEN–mTOR–SREBP1 axis to reprogram lipid metabolism and promote brain metastasis [PMID:37491281].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"The identification of TIG2/RARRES2 as a retinoid-responsive gene established that RAR-specific signaling transcriptionally controls a previously unknown secreted factor, linking retinoid biology to a novel downstream effector.\",\n      \"evidence\": \"Subtraction hybridization and Northern blot in skin raft cultures treated with receptor-selective retinoids\",\n      \"pmids\": [\"9204961\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Protein product function was unknown\",\n        \"Receptor for the gene product had not been identified\",\n        \"Mechanism of RAR-dependent transcriptional regulation not defined\"\n      ]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identification of chemerin (RARRES2 product) as the natural ligand of the orphan GPCR ChemR23/CMKLR1 resolved the receptor-ligand pairing and revealed that the bioactive form (residues 21–154) is generated by proteolytic processing of a 163-aa propeptide.\",\n      \"evidence\": \"Reverse pharmacology screening of hemofiltrate-derived peptides; biochemical characterization of processed forms\",\n      \"pmids\": [\"14675762\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The specific proteases responsible for C-terminal processing were not identified\",\n        \"Whether additional processed forms exist was unknown\",\n        \"Downstream intracellular signaling cascades activated by ChemR23 were uncharacterized\"\n      ]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Biochemical isolation of two distinct C-terminally processed bioactive chemerin forms (ending at F156 and A155) demonstrated that multiple cleavage events generate active species, establishing that regulated proteolysis tunes chemerin bioactivity.\",\n      \"evidence\": \"Heparin-affinity and reversed-phase chromatography purification from CHO supernatant; Edman sequencing and MALDI-TOF-MS\",\n      \"pmids\": [\"15522723\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Identity of the processing proteases remained unknown\",\n        \"Relative potencies of different processed forms on ChemR23 were not compared\",\n        \"In vivo relevance of each form was not determined\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrating that chemerin suppresses progesterone/estradiol production and MAPK3/1 phosphorylation in granulosa cells via CMKLR1 established a CMKLR1-dependent mechanism for chemerin's regulation of reproductive steroidogenesis and oocyte maturation.\",\n      \"evidence\": \"In vitro granulosa cell and cumulus-oocyte complex cultures with recombinant chemerin; anti-CMKLR1 blocking antibody; immunoblotting\",\n      \"pmids\": [\"24671882\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"In vivo reproductive phenotype of chemerin deficiency was not shown\",\n        \"Whether additional chemerin receptors (GPR1, CCRL2) contribute in ovarian context was not tested\",\n        \"Precise mechanism linking CMKLR1 to STAR/CYP19A1 downregulation was not fully delineated\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Gain- and loss-of-function experiments showing RARRES2 promotes RSV replication identified chemerin as a host cell factor exploited by respiratory syncytial virus, expanding its functional repertoire beyond chemotaxis and metabolic regulation.\",\n      \"evidence\": \"cDNA overexpression in MDCK cells and siRNA knockdown in HEp-2/A549 cells with viral replication assays\",\n      \"pmids\": [\"26277777\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which RARRES2 promotes viral replication was not elucidated\",\n        \"Whether the effect requires CMKLR1 signaling or is receptor-independent was not tested\",\n        \"Not independently replicated by other groups\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showing that RARRES2 overexpression promotes β-catenin phosphorylation/degradation and inhibits p38 MAPK in adrenocortical carcinoma cells in a cell-intrinsic, immune-independent manner established chemerin as a tumor suppressor acting through Wnt/β-catenin and MAPK pathways.\",\n      \"evidence\": \"RARRES2 overexpression in ACC cell lines; proliferation/invasion assays; immunodeficient mouse xenograft; immunoblotting\",\n      \"pmids\": [\"28114280\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether the tumor-suppressive activity requires CMKLR1 or another receptor was not determined\",\n        \"Direct molecular target linking chemerin to β-catenin phosphorylation machinery was not identified\",\n        \"Relevance beyond adrenocortical carcinoma was not demonstrated\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Multi-omics analysis revealing that RARRES2 loss activates PTEN–mTOR–SREBP1 signaling and reprograms lipid metabolism to promote brain metastasis in TNBC established chemerin as a regulator of lipid metabolic adaptation in cancer dissemination.\",\n      \"evidence\": \"Transcriptomics and lipidomics with RARRES2 knockdown/overexpression in TNBC cells; in vivo brain metastasis models; PTEN/mTOR/SREBP1 immunoblotting\",\n      \"pmids\": [\"37491281\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct biochemical link between chemerin and PTEN regulation was not defined\",\n        \"Single laboratory finding without independent replication\",\n        \"Whether the PTEN–mTOR axis operates through CMKLR1 in this context was not addressed\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the identity of the specific proteases that generate bioactive chemerin forms in vivo, the relative contributions of CMKLR1, GPR1, and CCRL2 to chemerin's diverse tissue-specific functions, and the direct molecular mechanism by which chemerin controls β-catenin degradation and PTEN–mTOR signaling.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"In vivo processing proteases not identified\",\n        \"Receptor specificity for tumor-suppressive and metabolic functions not resolved\",\n        \"No structural model of the chemerin–CMKLR1 signaling complex\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [1, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [1, 2, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0162582\", \"supporting_discovery_ids\": [1, 3, 4]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 3, 4]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"CMKLR1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\nWait, I need to fix the pathway entry. Let me correct that:\n\n```json\n{\n  \"mechanistic_narrative\": \"RARRES2 encodes chemerin, a secreted chemoattractant protein that functions as the natural ligand for the GPCR ChemR23/CMKLR1, regulating immune cell chemotaxis, steroidogenesis, and tumor-suppressive signaling. Originally identified as a retinoid-responsive gene induced by RAR-selective (but not RXR-selective) retinoids in a skin raft culture system [PMID:9204961], RARRES2 is synthesized as a 163-amino-acid prepropeptide that undergoes C-terminal proteolytic processing to yield bioactive forms (residues 21–154 or 20–155/156) [PMID:14675762, PMID:15522723]. Through CMKLR1, chemerin suppresses steroidogenesis by reducing STAR, CYP19A1, and MAPK3/1 phosphorylation in granulosa cells [PMID:24671882], and acts as a cell-intrinsic tumor suppressor by promoting β-catenin degradation and inhibiting p38 MAPK in adrenocortical carcinoma [PMID:28114280], while its loss in triple-negative breast cancer activates the PTEN–mTOR–SREBP1 axis to reprogram lipid metabolism and promote brain metastasis [PMID:37491281].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"The identification of TIG2/RARRES2 as a retinoid-responsive gene established that RAR-specific signaling transcriptionally controls a previously unknown secreted factor, linking retinoid biology to a novel downstream effector.\",\n      \"evidence\": \"Subtraction hybridization and Northern blot in skin raft cultures treated with receptor-selective retinoids\",\n      \"pmids\": [\"9204961\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Protein product function was unknown\",\n        \"Receptor for the gene product had not been identified\",\n        \"Mechanism of RAR-dependent transcriptional regulation not defined\"\n      ]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identification of chemerin (RARRES2 product) as the natural ligand of the orphan GPCR ChemR23/CMKLR1 resolved the receptor-ligand pairing and revealed that the bioactive form (residues 21–154) is generated by proteolytic processing of a 163-aa propeptide.\",\n      \"evidence\": \"Reverse pharmacology screening of hemofiltrate-derived peptides; biochemical characterization of processed forms\",\n      \"pmids\": [\"14675762\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The specific proteases responsible for C-terminal processing were not identified\",\n        \"Whether additional processed forms exist was unknown\",\n        \"Downstream intracellular signaling cascades activated by ChemR23 were uncharacterized\"\n      ]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Biochemical isolation of two distinct C-terminally processed bioactive chemerin forms (ending at F156 and A155) demonstrated that multiple cleavage events generate active species, establishing that regulated proteolysis tunes chemerin bioactivity.\",\n      \"evidence\": \"Heparin-affinity and reversed-phase chromatography purification from CHO supernatant; Edman sequencing and MALDI-TOF-MS\",\n      \"pmids\": [\"15522723\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Identity of the processing proteases remained unknown\",\n        \"Relative potencies of different processed forms on ChemR23 were not compared\",\n        \"In vivo relevance of each form was not determined\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrating that chemerin suppresses progesterone/estradiol production and MAPK3/1 phosphorylation in granulosa cells via CMKLR1 established a CMKLR1-dependent mechanism for chemerin's regulation of reproductive steroidogenesis and oocyte maturation.\",\n      \"evidence\": \"In vitro granulosa cell and cumulus-oocyte complex cultures with recombinant chemerin; anti-CMKLR1 blocking antibody; immunoblotting\",\n      \"pmids\": [\"24671882\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"In vivo reproductive phenotype of chemerin deficiency was not shown\",\n        \"Whether additional chemerin receptors (GPR1, CCRL2) contribute in ovarian context was not tested\",\n        \"Precise mechanism linking CMKLR1 to STAR/CYP19A1 downregulation was not fully delineated\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Gain- and loss-of-function experiments showing RARRES2 promotes RSV replication identified chemerin as a host cell factor exploited by respiratory syncytial virus, expanding its functional repertoire beyond chemotaxis and metabolic regulation.\",\n      \"evidence\": \"cDNA overexpression in MDCK cells and siRNA knockdown in HEp-2/A549 cells with viral replication assays\",\n      \"pmids\": [\"26277777\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which RARRES2 promotes viral replication was not elucidated\",\n        \"Whether the effect requires CMKLR1 signaling or is receptor-independent was not tested\",\n        \"Not independently replicated by other groups\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showing that RARRES2 overexpression promotes β-catenin phosphorylation/degradation and inhibits p38 MAPK in adrenocortical carcinoma cells in a cell-intrinsic, immune-independent manner established chemerin as a tumor suppressor acting through Wnt/β-catenin and MAPK pathways.\",\n      \"evidence\": \"RARRES2 overexpression in ACC cell lines; proliferation/invasion assays; immunodeficient mouse xenograft; immunoblotting\",\n      \"pmids\": [\"28114280\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether the tumor-suppressive activity requires CMKLR1 or another receptor was not determined\",\n        \"Direct molecular target linking chemerin to β-catenin phosphorylation machinery was not identified\",\n        \"Relevance beyond adrenocortical carcinoma was not demonstrated\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Multi-omics analysis revealing that RARRES2 loss activates PTEN–mTOR–SREBP1 signaling and reprograms lipid metabolism to promote brain metastasis in TNBC established chemerin as a regulator of lipid metabolic adaptation in cancer dissemination.\",\n      \"evidence\": \"Transcriptomics and lipidomics with RARRES2 knockdown/overexpression in TNBC cells; in vivo brain metastasis models; PTEN/mTOR/SREBP1 immunoblotting\",\n      \"pmids\": [\"37491281\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct biochemical link between chemerin and PTEN regulation was not defined\",\n        \"Single laboratory finding without independent replication\",\n        \"Whether the PTEN–mTOR axis operates through CMKLR1 in this context was not addressed\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the identity of the specific proteases that generate bioactive chemerin forms in vivo, the relative contributions of CMKLR1, GPR1, and CCRL2 to chemerin's diverse tissue-specific functions, and the direct molecular mechanism by which chemerin controls β-catenin degradation and PTEN–mTOR signaling.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"In vivo processing proteases not identified\",\n        \"Receptor specificity for tumor-suppressive and metabolic functions not resolved\",\n        \"No structural model of the chemerin–CMKLR1 signaling complex\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [1, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [1, 2, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 3, 4]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"CMKLR1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}