{"gene":"CCL23","run_date":"2026-04-28T17:28:52","timeline":{"discoveries":[{"year":1999,"finding":"CCL23 (MPIF-1) binds specifically to CCR1 on monocytes and dendritic cells, competing with MIP-1α but not MIP-1β or MCP-1 for binding sites. Signal transduction proceeds through G proteins (pertussis toxin-sensitive), leading to phospholipase C activation, protein kinase C, calcium flux from both extracellular and intracellular pools, and phospholipase A2 activation, which is required for filamentous actin formation and chemotaxis.","method":"Radioligand competition binding ([125I]MIP-1α), calcium flux assays in CCR1-transfected HEK-293 cells and primary monocytes/DCs, GTP-γS inhibition, pertussis toxin pretreatment, PLC inhibitors, PLA2 inhibitors, [3H]arachidonic acid release assay","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal biochemical assays with pharmacological inhibitors in both transfected cells and primary cells","pmids":["9886417"],"is_preprint":false},{"year":2000,"finding":"CCL23 (MPIF-1) is a monomeric CC chemokine. NMR solution structure reveals a canonical chemokine fold (three β-strands and an overlying α-helix) plus two additional cysteines forming an extra disulfide bond beyond the conserved four. The extended N-terminus exists as a proprotein form; both full-length and truncated forms are monomers. The highly basic protein (pI >9) contains distinct positively charged pockets consistent with proteoglycan binding.","method":"NMR spectroscopy with backbone dynamics analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — solution structure determined by NMR with dynamics analysis","pmids":["11060285"],"is_preprint":false},{"year":2000,"finding":"CCL23 (CKβ-8) is chemotactic for human osteoclast precursors (TRAP-positive mononuclear cells from osteoclastoma tissue) at EC(max) of 0.1–0.3 nM, and this activity is partially cross-desensitized by RANTES and MIP-1α, implicating CCR1 as the mediating receptor. CCL23 had no chemotactic activity on osteoblasts.","method":"Chemotaxis assay with CCR1 cross-desensitization experiments; in situ hybridization for CCL23 mRNA in human fetal bone; immunolocalization of protein in osteophytic tissue","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2-3 — chemotaxis with receptor cross-desensitization; single lab","pmids":["10737895"],"is_preprint":false},{"year":1999,"finding":"CCL23 (MPIF-1) is constitutively produced and released by monocyte-derived dendritic cells but not by macrophages or resting monocytes. CD40 ligation and IFN-γ treatment, unlike LPS or TNF-α, suppress MPIF-1 transcript and protein release from dendritic cells, indicating a distinct regulatory program compared to other CC/CXC chemokines.","method":"ELISA, Northern blot for MPIF-1 transcript, stimulation of monocyte-derived and CD34+-derived DCs with LPS, TNF-α, CD40L, IFN-γ","journal":"Journal of leukocyte biology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple stimuli tested with both protein and mRNA readouts in primary cells; single lab","pmids":["10380905"],"is_preprint":false},{"year":2005,"finding":"CCL23 promotes chemotactic migration and tube formation of vascular endothelial cells and neovascularization in the chick chorioallantoic membrane via CCR1 (blocked by pertussis toxin or anti-CCR1 antibody). An N-terminally truncated form of CCL23 is at least 100-fold more potent than the intact form in angiogenic activity and comparable to FGF.","method":"Transwell chemotaxis assay, endothelial tube formation assay, chick chorioallantoic membrane neovascularization assay, pertussis toxin and antibody neutralization","journal":"Cytokine","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro and in vivo angiogenesis assays with receptor-blocking and Gi-protein inhibition, N-terminal truncation structure-activity comparison","pmids":["15927850"],"is_preprint":false},{"year":2005,"finding":"CCL23 enhances expression of MMP-2 (but not MMP-9, TIMP-1, TIMP-2, or MT1-MMP) in endothelial cells at the transcriptional level, and promotes endothelial cell invasion through Matrigel in an MMP-2-dependent manner (blocked by MMP inhibitors GM6001 and MMP-2 Inhibitor I, as well as anti-CCL23 and anti-CCR1 antibodies).","method":"RT-PCR, Western blot, MMP-2/Luc reporter gene assay, Matrigel invasion assay, neutralizing antibody blockade, MMP inhibitor studies","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods (transcriptional reporter, protein, invasion, inhibitors) in a single lab","pmids":["16378600"],"is_preprint":false},{"year":2007,"finding":"Proinflammatory proteases cleave the alternatively spliced CCL23 isoform (CKβ8-1) immediately N-terminal to the 18-residue inserted domain, releasing a peptide termed SHAAGtide that acts as a potent FPRL1 (CCR12) agonist (50-100-fold more potent than other known FPRL1 ligands) and recruits monocytes and neutrophils in vitro and in vivo, while the remaining CCL23 body retains enhanced CCR1 activity. Sequential further cleavage within SHAAGtide abolishes FPRL1 activity.","method":"Protease incubation with synovial fluid and defined proteases, calcium flux assay, Transwell migration assay, in vivo leukocyte recruitment, MALDI-TOF-MS cleavage site mapping","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 — biochemical cleavage mapping by MS, functional receptor assays (CCR1 and FPRL1), in vitro and in vivo validation","pmids":["17513790"],"is_preprint":false},{"year":2007,"finding":"IL-4 and IL-13 induce CCL23 expression in human peripheral blood monocytes in a STAT6-dependent manner. A canonical STAT6 binding site in the CCL23 promoter is required for IL-4 responsiveness; mutation of this site abolishes induction, and two tandem copies confer responsiveness to a heterologous promoter. A downstream negative cis-element suppresses IL-4-induced CCL23 expression.","method":"Promoter reporter gene assays with STAT6 site mutagenesis, monocyte stimulation with IL-4/IL-13, EMSA, heterologous promoter constructs","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 — promoter reporter with site-specific mutagenesis and EMSA, multiple cytokine conditions","pmids":["17371990"],"is_preprint":false},{"year":2007,"finding":"The CCL23 promoter region −293 to +31 is critical for PMA-induced expression in U937 monocytoid cells. Transcription factor binding sites at −269/−264 (NFAT), −167/−159 (NF-κB), and −51/−43 (AP-1) are each required for PMA-induced CCL23 expression, confirmed by factor binding and pathway-specific inhibitor studies.","method":"Serial deletion reporter analysis, EMSA for transcription factor binding, pharmacological signal pathway inhibitors","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 — promoter deletion + EMSA + inhibitor confirmation; single lab","pmids":["17368823"],"is_preprint":false},{"year":2009,"finding":"CCL23 (CKβ8) and its isoform CKβ8-1 induce chemotaxis and cell migration through a Gi/Go protein → PLC → PKCδ → NF-κB signaling pathway. Both isoforms activate NF-κB and increase mRNA expression of pro-inflammatory cytokines and adhesion molecules. CKβ8 and CKβ8-1 mRNA levels are elevated in foam cells, implicating CCL23 in atherosclerosis-related inflammation.","method":"Transwell chemotaxis assay with pharmacological inhibitors (Gi/Go, PLC, PKCδ, NF-κB), NF-κB activation assays, RT-PCR for inflammatory mediators in foam cells","journal":"Life sciences","confidence":"Medium","confidence_rationale":"Tier 2 — chemotaxis with multiple inhibitors delineating pathway order; single lab","pmids":["19951712"],"is_preprint":false},{"year":2009,"finding":"CCL23 up-regulates KDR/Flk-1 (VEGFR2) mRNA and protein expression in endothelial cells primarily at the transcriptional level, mediated through SAPK/JNK phosphorylation. CCL23-induced KDR/Flk-1 up-regulation potentiates VEGF-induced ERK phosphorylation and enhances VEGF-driven endothelial proliferation and migration.","method":"PCR, Western blot, confocal microscopy, KDR/Flk-1 reporter assay, SAPK/JNK inhibitor, ERK phosphorylation assay, proliferation and migration assays","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — transcriptional reporter + signaling inhibitor + downstream functional readouts; single lab","pmids":["19265684"],"is_preprint":false},{"year":2010,"finding":"CCL23 (CKβ8) and CKβ8-1 induce cell-cycle progression and up-regulate cyclin D3 and cyclin B1 as well as immediate early genes c-Myc and Egr-1 through a Gi/Go protein → PLC → PKCδ → ERK1/2 cascade.","method":"Cell cycle analysis, ERK1/2 phosphorylation assay, pathway inhibitor studies (Gi/Go, PLC, PKCδ), cyclin expression by Western blot","journal":"Cytokine","confidence":"Medium","confidence_rationale":"Tier 2 — cell cycle readouts with ordered pathway inhibitor dissection; single lab","pmids":["20097574"],"is_preprint":false},{"year":2011,"finding":"Matrix metalloproteinases (MMPs) cleave full-length CCL23(1-99) within its unique 32-amino acid extended N-terminus, generating CCL23(26-99) as the principal product. Unlike most CC chemokines where MMP cleavage inactivates, MMP-processed CCL23(26-99) is a stronger agonist in calcium flux assays and Transwell migration assays of CCR1-transfected cells and THP-1 monocytes compared to full-length CCL23. Cleavage sites were identified by MALDI-TOF-MS.","method":"Family-wide MMP processing screen, MALDI-TOF-MS cleavage site sequencing, calcium flux assay, Transwell migration assay in CCR1 transfectants and THP-1 cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution of MMP cleavage, MS-confirmed cleavage sites, functional receptor assays","pmids":["22147696"],"is_preprint":false},{"year":2011,"finding":"CCL23 stimulates chemotaxis of THP-1 monocytes, enhances expression of adhesion molecule CD11c, and promotes release of MMP-2 from monocytes. Proatherogenic stimuli (oxidized LDL, oxidative stress) markedly enhance CCL23 release from THP-1 macrophages.","method":"Chemotaxis assay, flow cytometry for CD11c, zymography for MMP-2, ELISA for CCL23 release, RT-PCR for CCL23 in atherosclerotic lesions","journal":"Inflammation research","confidence":"Medium","confidence_rationale":"Tier 2-3 — multiple functional readouts in monocyte/macrophage model; single lab","pmids":["21656154"],"is_preprint":false},{"year":2017,"finding":"Human neutrophils produce and release CCL23 in response to TLR7/8 agonist R848 and, to a lesser extent, LPS, Pam3CSK4, and TNF-α, but not IL-4. On a per-cell basis, R848-activated neutrophils produce more CCL23 than autologous CD14+ monocytes. IFNα negatively modulates CCL23 production by R848-stimulated neutrophils.","method":"ELISA for CCL23 protein, RT-PCR/real-time PCR for mRNA, stimulation of purified primary neutrophils and autologous monocytes with multiple TLR agonists and cytokines","journal":"Frontiers in cellular and infection microbiology","confidence":"Medium","confidence_rationale":"Tier 2 — primary cell comparison between neutrophils and monocytes with multiple stimuli and cytokine modulation","pmids":["28553619"],"is_preprint":false},{"year":2021,"finding":"CCL23 expression in liver cancer cells is transcriptionally regulated by ESR1. Conversely, CCL23 suppresses AKT signaling, which promotes ESR1 expression, forming a feedback loop. CCL23 acting through CCR1 also recruits CD8+ T cell infiltration and inhibits cancer cell proliferation, stemness, and mobility in liver cancer.","method":"Bioinformatics screening, RNA-seq, co-immunoprecipitation, AKT pathway western blot, CD8+ T cell infiltration analysis, functional assays (proliferation, stemness, migration) with CCL23 overexpression/knockdown","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2-3 — multiple functional assays and mechanistic pathway identification; single lab","pmids":["34050704"],"is_preprint":false},{"year":2022,"finding":"Macrophage-derived CCL23 induces upregulation of immune checkpoint proteins (CTLA-4, TIGIT, TIM-3, LAG-3) on CD8+ T cells, promoting T-cell exhaustion, via phosphorylation of GSK3β in CD8+ T cells.","method":"ELISA for CCL23 in ascites, flow cytometry for exhaustion markers, phosphokinase array, Western blot for GSK3β phosphorylation, in vitro CCL23 treatment of CD8+ T cells","journal":"British journal of cancer","confidence":"Medium","confidence_rationale":"Tier 2 — phosphokinase array plus western blot validation, flow cytometry of functional outcome; single lab","pmids":["35750747"],"is_preprint":false},{"year":2022,"finding":"CCL23 interacts with transcription factor TFAP4 (demonstrated by co-immunoprecipitation), and overexpression of CCL23 inhibits HCC cell proliferation, invasion, and angiogenesis (tube formation, VEGFA/VEGFR expression) in vitro, while co-expression of TFAP4 blocks these CCL23-mediated inhibitory effects.","method":"Co-immunoprecipitation, overexpression plasmid transfection, proliferation assay, invasion assay, HUVEC tube formation assay, RT-qPCR and Western blot","journal":"Bioengineered","confidence":"Medium","confidence_rationale":"Tier 2-3 — co-IP establishing interaction, multiple functional assays with rescue; single lab","pmids":["35001801"],"is_preprint":false},{"year":2023,"finding":"CCL23 inhibits lung leukocyte recruitment in a primate cardiopulmonary bypass model by slowing bone marrow transit of PMNs and monocytes and suppressing their circulatory release and alveolar appearance, without suppressing CD11b/L-selectin expression or post-surgical cytokine levels in BALF.","method":"In vivo primate CPB model, BrdU labeling of BM-derived leukocytes, flow cytometry, bronchoalveolar lavage with cytokine ELISA; CCL23 given intravenously","journal":"Heart, lung & circulation","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo primate model with BrdU tracking and flow cytometry, defined functional phenotype","pmids":["36628657"],"is_preprint":false},{"year":1999,"finding":"The CCL23 gene (MPIF-1/SCYA23) is located on human chromosome 17q11.2, has four exons (unlike the three-exon structure of most CC chemokines), and shares high conservation with neighboring HCC-2 gene (SCYA15) including introns and flanking sequences, indicating recent gene duplication.","method":"Large-scale genomic sequencing (random shotgun), gene prediction, EST similarity search","journal":"Journal of interferon & cytokine research","confidence":"High","confidence_rationale":"Tier 1 — complete genomic sequence determination of a 181 kb region","pmids":["10213461"],"is_preprint":false},{"year":2025,"finding":"CCL23-stimulated THP-1 macrophages exhibit reduced CXCL10 secretion via STAT-3 activation, suggesting CCL23 modulates macrophage cytokine output in the tumor microenvironment.","method":"ELISA for CXCL10, in vitro CCL23 peptide stimulation of differentiated THP-1 monocytes, STAT-3 pathway analysis","journal":"Cancers","confidence":"Low","confidence_rationale":"Tier 3 — single lab, single method with pathway inference; limited mechanistic follow-up","pmids":["41463176"],"is_preprint":false}],"current_model":"CCL23 (also known as MPIF-1, CKβ8, or MIP-3) is a monomeric CC chemokine that signals primarily through CCR1 via Gi/Go proteins, activating a cascade involving phospholipase C, PKCδ, NF-κB, ERK1/2, and SAPK/JNK to drive monocyte/leukocyte chemotaxis, cell-cycle progression, and endothelial cell migration; its N-terminal extended proprotein form is proteolytically activated by MMPs to generate a more potent CCR1 agonist (CCL23(26-99)), while inflammatory proteases can also cleave the alternatively spliced isoform CKβ8-1 to release an 18-residue peptide (SHAAGtide) that is a high-potency FPRL1 agonist; CCL23 further promotes angiogenesis by up-regulating MMP-2 and KDR/Flk-1 expression in endothelial cells, and its transcription is regulated by a STAT6-dependent IL-4/IL-13 pathway as well as NFAT, NF-κB, and AP-1 elements in its promoter."},"narrative":{"teleology":[{"year":1999,"claim":"Identification of CCR1 as the specific receptor and delineation of the Gi-protein–PLC–PLA2 signaling cascade established the core signal transduction pathway underlying CCL23-driven monocyte chemotaxis.","evidence":"Radioligand competition binding, calcium flux in CCR1 transfectants and primary monocytes/DCs, pertussis toxin and PLC/PLA2 inhibitor studies","pmids":["9886417"],"confidence":"High","gaps":["Downstream transcription factor targets of this cascade were not identified","Relative contributions of PLA2 vs PLC arms to chemotaxis not quantified"]},{"year":1999,"claim":"Genomic characterization revealed an atypical four-exon structure and recent duplication origin with HCC-2, while expression profiling showed constitutive CCL23 production by dendritic cells that is suppressed by IFN-γ and CD40 ligation, distinguishing its regulation from other CC chemokines.","evidence":"Genomic shotgun sequencing of 17q11.2 region; ELISA and Northern blot of monocyte-derived and CD34+-derived DCs with multiple stimuli","pmids":["10213461","10380905"],"confidence":"High","gaps":["Functional significance of the fourth exon-encoded N-terminal extension was not yet known","Mechanism of CD40L-mediated suppression not defined"]},{"year":2000,"claim":"NMR structure determination showed CCL23 is a monomer with a canonical chemokine fold plus an extra disulfide bond and basic surface patches, providing a structural framework for understanding its extended N-terminus as a proprotein domain and its proteoglycan interactions.","evidence":"NMR solution structure with backbone dynamics analysis","pmids":["11060285"],"confidence":"High","gaps":["Proteoglycan binding was inferred from surface charge but not directly measured","No co-crystal or NMR structure with CCR1"]},{"year":2005,"claim":"Discovery that CCL23 promotes angiogenesis—driving endothelial chemotaxis, tube formation, and in vivo neovascularization through CCR1, with an N-terminally truncated form 100-fold more potent—expanded its role from leukocyte chemoattractant to vascular biology effector.","evidence":"Transwell migration, tube formation, chick CAM neovascularization assay with pertussis toxin and anti-CCR1 blockade; structure-activity comparison of truncated vs full-length CCL23","pmids":["15927850"],"confidence":"High","gaps":["Identity of the endogenous protease responsible for N-terminal truncation in vivo was unknown","Endothelial CCR1 expression levels in different vascular beds not characterized"]},{"year":2005,"claim":"CCL23 was shown to transcriptionally upregulate MMP-2 in endothelial cells and drive MMP-2-dependent Matrigel invasion, linking its angiogenic activity to extracellular matrix remodeling.","evidence":"MMP-2 promoter-reporter, RT-PCR, Western blot, Matrigel invasion with MMP inhibitors and neutralizing antibodies","pmids":["16378600"],"confidence":"Medium","gaps":["Transcription factor mediating MMP-2 promoter activation by CCL23 not identified","No in vivo confirmation of MMP-2 dependence"]},{"year":2007,"claim":"Three convergent studies clarified CCL23 transcriptional regulation—STAT6-dependent IL-4/IL-13 induction in monocytes and NFAT/NF-κB/AP-1-dependent PMA induction—and revealed that proteolytic processing of the CKβ8-1 isoform releases SHAAGtide, a uniquely potent FPRL1 agonist for neutrophil and monocyte recruitment.","evidence":"Promoter mutagenesis/EMSA for STAT6 and NFAT/NF-κB/AP-1; protease incubation with MS-confirmed cleavage sites, calcium flux, Transwell migration, in vivo leukocyte recruitment","pmids":["17371990","17368823","17513790"],"confidence":"High","gaps":["Relative in vivo contribution of FPRL1 vs CCR1 signaling during inflammation unknown","Nature of the downstream negative cis-element in the STAT6-regulated promoter not fully characterized"]},{"year":2009,"claim":"Detailed signaling pathway dissection established that CCL23 activates a Gi/Go → PLC → PKCδ → NF-κB cascade for chemotaxis and proinflammatory gene induction, while a parallel SAPK/JNK pathway mediates KDR/Flk-1 upregulation that potentiates VEGF-driven endothelial proliferation.","evidence":"Ordered pharmacological inhibitor studies in chemotaxis and NF-κB assays; KDR promoter-reporter and SAPK/JNK inhibitor studies with downstream ERK phosphorylation readout","pmids":["19951712","19265684"],"confidence":"Medium","gaps":["Whether PKCδ and SAPK/JNK pathways branch from the same or distinct upstream nodes not resolved","In vivo relevance of KDR upregulation to CCL23-driven angiogenesis not tested"]},{"year":2010,"claim":"CCL23 was found to drive cell-cycle progression by upregulating cyclins D3 and B1 plus immediate-early genes c-Myc and Egr-1 via the Gi/Go → PLC → PKCδ → ERK1/2 pathway, extending its functional repertoire beyond chemotaxis to proliferative signaling.","evidence":"Cell cycle analysis, ERK1/2 phosphorylation, cyclin expression by Western blot, ordered inhibitor dissection","pmids":["20097574"],"confidence":"Medium","gaps":["Cell type generality of cell-cycle effects not established beyond the model used","Direct link between ERK1/2 and cyclin D3/B1 transcription not demonstrated"]},{"year":2011,"claim":"A systematic MMP processing screen identified MMPs as the proteases that cleave the extended N-terminus of full-length CCL23(1-99) to generate the more potent CCL23(26-99) agonist, uniquely demonstrating that MMP cleavage activates rather than inactivates a CC chemokine.","evidence":"Family-wide in vitro MMP screen, MALDI-TOF-MS cleavage site mapping, calcium flux and Transwell migration in CCR1 transfectants and THP-1 cells","pmids":["22147696"],"confidence":"High","gaps":["Which specific MMP family members are the physiological activators in vivo remains unclear","Structural basis for enhanced CCR1 agonism of CCL23(26-99) not determined"]},{"year":2017,"claim":"Neutrophils were identified as a significant cellular source of CCL23, particularly upon TLR7/8 stimulation, with IFNα serving as a negative modulator—broadening the producer cell repertoire beyond monocytes and dendritic cells.","evidence":"ELISA and RT-qPCR in purified primary neutrophils vs autologous monocytes with multiple TLR agonists and cytokines","pmids":["28553619"],"confidence":"Medium","gaps":["Receptor and signaling pathway mediating TLR7/8-induced CCL23 transcription in neutrophils not mapped","In vivo contribution of neutrophil-derived CCL23 to inflammation not tested"]},{"year":2022,"claim":"In the tumor microenvironment, macrophage-derived CCL23 was shown to promote CD8+ T-cell exhaustion by upregulating CTLA-4, TIGIT, TIM-3, and LAG-3 through GSK3β phosphorylation, establishing a new immunomodulatory axis beyond chemotaxis.","evidence":"Phosphokinase array and Western blot for GSK3β in CD8+ T cells, flow cytometry for exhaustion markers, ELISA for CCL23 in ascites","pmids":["35750747"],"confidence":"Medium","gaps":["Receptor on CD8+ T cells mediating GSK3β phosphorylation not identified (CCR1 vs other)","In vivo relevance to tumor immune evasion not confirmed by loss-of-function in animal models"]},{"year":null,"claim":"Key unresolved questions include the structural basis for enhanced CCR1 agonism of MMP-processed CCL23, the receptor mediating T-cell exhaustion effects, and the net in vivo balance between CCL23's pro-inflammatory leukocyte recruitment and immunosuppressive T-cell exhaustion functions in disease settings.","evidence":"","pmids":[],"confidence":"Low","gaps":["No CCL23–CCR1 co-structure available","No genetic loss-of-function model in mammals reported","Relative in vivo roles of CCR1 vs FPRL1 pathways not dissected"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[0,4,6,12]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,6]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[3,6,12,14]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,6,9,14,16]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,9,10,11,15]}],"complexes":[],"partners":["CCR1","FPRL1","MMP2","TFAP4","ESR1"],"other_free_text":[]},"mechanistic_narrative":"CCL23 is a monomeric CC chemokine that functions as a pleiotropic mediator of leukocyte recruitment, angiogenesis, and immune regulation through signaling primarily via CCR1 and, via proteolytic processing of its alternatively spliced isoform, through FPRL1. Full-length CCL23 contains a unique 32-amino-acid N-terminal extension that is cleaved by matrix metalloproteinases to generate CCL23(26-99), a more potent CCR1 agonist, while inflammatory protease processing of the CKβ8-1 splice variant releases the SHAAGtide peptide, a high-potency FPRL1 agonist for monocyte and neutrophil recruitment [PMID:22147696, PMID:17513790]. CCR1-mediated signaling proceeds through Gi/Go proteins to activate PLC, PKCδ, NF-κB, ERK1/2, and SAPK/JNK, driving monocyte chemotaxis, cell-cycle progression, endothelial migration, MMP-2 upregulation, and KDR/Flk-1-dependent potentiation of VEGF signaling in angiogenesis [PMID:9886417, PMID:19951712, PMID:15927850, PMID:19265684]. CCL23 transcription in monocytes is induced by IL-4/IL-13 through a STAT6-dependent promoter element and by PMA through cooperative NFAT, NF-κB, and AP-1 sites, while in the tumor microenvironment macrophage-derived CCL23 promotes CD8+ T-cell exhaustion via GSK3β phosphorylation [PMID:17371990, PMID:17368823, PMID:35750747]."},"prefetch_data":{"uniprot":{"accession":"P55773","full_name":"C-C motif chemokine 23","aliases":["CK-beta-8","CKB-8","Macrophage inflammatory protein 3","MIP-3","Myeloid progenitor inhibitory factor 1","MPIF-1","Small-inducible cytokine A23"],"length_aa":120,"mass_kda":13.4,"function":"Shows chemotactic activity for monocytes, resting T-lymphocytes, and neutrophils, but not for activated lymphocytes. Inhibits proliferation of myeloid progenitor cells in colony formation assays. This protein can bind heparin. Binds CCR1. CCL23(19-99), CCL23(22-99), CCL23(27-99), CCL23(30-99) are more potent chemoattractants than CCL23","subcellular_location":"Secreted","url":"https://www.uniprot.org/uniprotkb/P55773/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CCL23","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CCL23","total_profiled":1310},"omim":[{"mim_id":"602494","title":"CHEMOKINE, CC MOTIF, LIGAND 23; CCL23","url":"https://www.omim.org/entry/602494"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/CCL23"},"hgnc":{"alias_symbol":["Ckb-8","MPIF-1","MIP-3","CKb8"],"prev_symbol":["SCYA23"]},"alphafold":{"accession":"P55773","domains":[{"cath_id":"2.40.50.40","chopping":"55-120","consensus_level":"medium","plddt":95.0518,"start":55,"end":120}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P55773","model_url":"https://alphafold.ebi.ac.uk/files/AF-P55773-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P55773-F1-predicted_aligned_error_v6.png","plddt_mean":76.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CCL23","jax_strain_url":"https://www.jax.org/strain/search?query=CCL23"},"sequence":{"accession":"P55773","fasta_url":"https://rest.uniprot.org/uniprotkb/P55773.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P55773/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P55773"}},"corpus_meta":[{"pmid":"11133838","id":"PMC_11133838","title":"Inducible expression of a CC chemokine liver- and activation-regulated chemokine (LARC)/macrophage inflammatory protein (MIP)-3 alpha/CCL20 by epidermal keratinocytes and its role in atopic dermatitis.","date":"2001","source":"International immunology","url":"https://pubmed.ncbi.nlm.nih.gov/11133838","citation_count":145,"is_preprint":false},{"pmid":"18668547","id":"PMC_18668547","title":"Potential novel biomarkers of disease activity in rheumatoid arthritis patients: CXCL13, CCL23, transforming growth factor alpha, tumor necrosis factor receptor superfamily member 9, and macrophage colony-stimulating factor.","date":"2008","source":"Arthritis and rheumatism","url":"https://pubmed.ncbi.nlm.nih.gov/18668547","citation_count":112,"is_preprint":false},{"pmid":"11472439","id":"PMC_11472439","title":"Selective recruitment of CCR6-expressing cells by increased production of MIP-3 alpha in rheumatoid arthritis.","date":"2001","source":"Clinical and experimental immunology","url":"https://pubmed.ncbi.nlm.nih.gov/11472439","citation_count":109,"is_preprint":false},{"pmid":"10754294","id":"PMC_10754294","title":"The CC chemokine CK beta-11/MIP-3 beta/ELC/Exodus 3 mediates tumor rejection of murine breast cancer cells through NK cells.","date":"2000","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/10754294","citation_count":102,"is_preprint":false},{"pmid":"21497884","id":"PMC_21497884","title":"Increased expression of the chemokine CCL23 in eosinophilic chronic rhinosinusitis with nasal polyps.","date":"2011","source":"The Journal of allergy and clinical immunology","url":"https://pubmed.ncbi.nlm.nih.gov/21497884","citation_count":89,"is_preprint":false},{"pmid":"15927850","id":"PMC_15927850","title":"Human CC chemokine CCL23, a ligand for CCR1, induces endothelial cell migration and promotes angiogenesis.","date":"2005","source":"Cytokine","url":"https://pubmed.ncbi.nlm.nih.gov/15927850","citation_count":84,"is_preprint":false},{"pmid":"11994140","id":"PMC_11994140","title":"Expression of the C-C chemokine MIP-3 alpha/CCL20 in human epidermis with impaired permeability barrier function.","date":"2002","source":"Experimental dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/11994140","citation_count":81,"is_preprint":false},{"pmid":"16764701","id":"PMC_16764701","title":"Enhanced expression and clinical significance of CC-chemokine MIP-3 alpha in hepatocellular carcinoma.","date":"2006","source":"Scandinavian journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/16764701","citation_count":60,"is_preprint":false},{"pmid":"22147696","id":"PMC_22147696","title":"Biochemical analysis of matrix metalloproteinase activation of chemokines CCL15 and CCL23 and increased glycosaminoglycan binding of CCL16.","date":"2011","source":"The Journal of biological 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Signal transduction proceeds through G proteins (pertussis toxin-sensitive), leading to phospholipase C activation, protein kinase C, calcium flux from both extracellular and intracellular pools, and phospholipase A2 activation, which is required for filamentous actin formation and chemotaxis.\",\n      \"method\": \"Radioligand competition binding ([125I]MIP-1α), calcium flux assays in CCR1-transfected HEK-293 cells and primary monocytes/DCs, GTP-γS inhibition, pertussis toxin pretreatment, PLC inhibitors, PLA2 inhibitors, [3H]arachidonic acid release assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal biochemical assays with pharmacological inhibitors in both transfected cells and primary cells\",\n      \"pmids\": [\"9886417\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"CCL23 (MPIF-1) is a monomeric CC chemokine. NMR solution structure reveals a canonical chemokine fold (three β-strands and an overlying α-helix) plus two additional cysteines forming an extra disulfide bond beyond the conserved four. The extended N-terminus exists as a proprotein form; both full-length and truncated forms are monomers. The highly basic protein (pI >9) contains distinct positively charged pockets consistent with proteoglycan binding.\",\n      \"method\": \"NMR spectroscopy with backbone dynamics analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — solution structure determined by NMR with dynamics analysis\",\n      \"pmids\": [\"11060285\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"CCL23 (CKβ-8) is chemotactic for human osteoclast precursors (TRAP-positive mononuclear cells from osteoclastoma tissue) at EC(max) of 0.1–0.3 nM, and this activity is partially cross-desensitized by RANTES and MIP-1α, implicating CCR1 as the mediating receptor. CCL23 had no chemotactic activity on osteoblasts.\",\n      \"method\": \"Chemotaxis assay with CCR1 cross-desensitization experiments; in situ hybridization for CCL23 mRNA in human fetal bone; immunolocalization of protein in osteophytic tissue\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — chemotaxis with receptor cross-desensitization; single lab\",\n      \"pmids\": [\"10737895\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"CCL23 (MPIF-1) is constitutively produced and released by monocyte-derived dendritic cells but not by macrophages or resting monocytes. CD40 ligation and IFN-γ treatment, unlike LPS or TNF-α, suppress MPIF-1 transcript and protein release from dendritic cells, indicating a distinct regulatory program compared to other CC/CXC chemokines.\",\n      \"method\": \"ELISA, Northern blot for MPIF-1 transcript, stimulation of monocyte-derived and CD34+-derived DCs with LPS, TNF-α, CD40L, IFN-γ\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple stimuli tested with both protein and mRNA readouts in primary cells; single lab\",\n      \"pmids\": [\"10380905\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"CCL23 promotes chemotactic migration and tube formation of vascular endothelial cells and neovascularization in the chick chorioallantoic membrane via CCR1 (blocked by pertussis toxin or anti-CCR1 antibody). An N-terminally truncated form of CCL23 is at least 100-fold more potent than the intact form in angiogenic activity and comparable to FGF.\",\n      \"method\": \"Transwell chemotaxis assay, endothelial tube formation assay, chick chorioallantoic membrane neovascularization assay, pertussis toxin and antibody neutralization\",\n      \"journal\": \"Cytokine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro and in vivo angiogenesis assays with receptor-blocking and Gi-protein inhibition, N-terminal truncation structure-activity comparison\",\n      \"pmids\": [\"15927850\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"CCL23 enhances expression of MMP-2 (but not MMP-9, TIMP-1, TIMP-2, or MT1-MMP) in endothelial cells at the transcriptional level, and promotes endothelial cell invasion through Matrigel in an MMP-2-dependent manner (blocked by MMP inhibitors GM6001 and MMP-2 Inhibitor I, as well as anti-CCL23 and anti-CCR1 antibodies).\",\n      \"method\": \"RT-PCR, Western blot, MMP-2/Luc reporter gene assay, Matrigel invasion assay, neutralizing antibody blockade, MMP inhibitor studies\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (transcriptional reporter, protein, invasion, inhibitors) in a single lab\",\n      \"pmids\": [\"16378600\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Proinflammatory proteases cleave the alternatively spliced CCL23 isoform (CKβ8-1) immediately N-terminal to the 18-residue inserted domain, releasing a peptide termed SHAAGtide that acts as a potent FPRL1 (CCR12) agonist (50-100-fold more potent than other known FPRL1 ligands) and recruits monocytes and neutrophils in vitro and in vivo, while the remaining CCL23 body retains enhanced CCR1 activity. Sequential further cleavage within SHAAGtide abolishes FPRL1 activity.\",\n      \"method\": \"Protease incubation with synovial fluid and defined proteases, calcium flux assay, Transwell migration assay, in vivo leukocyte recruitment, MALDI-TOF-MS cleavage site mapping\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — biochemical cleavage mapping by MS, functional receptor assays (CCR1 and FPRL1), in vitro and in vivo validation\",\n      \"pmids\": [\"17513790\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"IL-4 and IL-13 induce CCL23 expression in human peripheral blood monocytes in a STAT6-dependent manner. A canonical STAT6 binding site in the CCL23 promoter is required for IL-4 responsiveness; mutation of this site abolishes induction, and two tandem copies confer responsiveness to a heterologous promoter. A downstream negative cis-element suppresses IL-4-induced CCL23 expression.\",\n      \"method\": \"Promoter reporter gene assays with STAT6 site mutagenesis, monocyte stimulation with IL-4/IL-13, EMSA, heterologous promoter constructs\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — promoter reporter with site-specific mutagenesis and EMSA, multiple cytokine conditions\",\n      \"pmids\": [\"17371990\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"The CCL23 promoter region −293 to +31 is critical for PMA-induced expression in U937 monocytoid cells. Transcription factor binding sites at −269/−264 (NFAT), −167/−159 (NF-κB), and −51/−43 (AP-1) are each required for PMA-induced CCL23 expression, confirmed by factor binding and pathway-specific inhibitor studies.\",\n      \"method\": \"Serial deletion reporter analysis, EMSA for transcription factor binding, pharmacological signal pathway inhibitors\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — promoter deletion + EMSA + inhibitor confirmation; single lab\",\n      \"pmids\": [\"17368823\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CCL23 (CKβ8) and its isoform CKβ8-1 induce chemotaxis and cell migration through a Gi/Go protein → PLC → PKCδ → NF-κB signaling pathway. Both isoforms activate NF-κB and increase mRNA expression of pro-inflammatory cytokines and adhesion molecules. CKβ8 and CKβ8-1 mRNA levels are elevated in foam cells, implicating CCL23 in atherosclerosis-related inflammation.\",\n      \"method\": \"Transwell chemotaxis assay with pharmacological inhibitors (Gi/Go, PLC, PKCδ, NF-κB), NF-κB activation assays, RT-PCR for inflammatory mediators in foam cells\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — chemotaxis with multiple inhibitors delineating pathway order; single lab\",\n      \"pmids\": [\"19951712\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CCL23 up-regulates KDR/Flk-1 (VEGFR2) mRNA and protein expression in endothelial cells primarily at the transcriptional level, mediated through SAPK/JNK phosphorylation. CCL23-induced KDR/Flk-1 up-regulation potentiates VEGF-induced ERK phosphorylation and enhances VEGF-driven endothelial proliferation and migration.\",\n      \"method\": \"PCR, Western blot, confocal microscopy, KDR/Flk-1 reporter assay, SAPK/JNK inhibitor, ERK phosphorylation assay, proliferation and migration assays\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — transcriptional reporter + signaling inhibitor + downstream functional readouts; single lab\",\n      \"pmids\": [\"19265684\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"CCL23 (CKβ8) and CKβ8-1 induce cell-cycle progression and up-regulate cyclin D3 and cyclin B1 as well as immediate early genes c-Myc and Egr-1 through a Gi/Go protein → PLC → PKCδ → ERK1/2 cascade.\",\n      \"method\": \"Cell cycle analysis, ERK1/2 phosphorylation assay, pathway inhibitor studies (Gi/Go, PLC, PKCδ), cyclin expression by Western blot\",\n      \"journal\": \"Cytokine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — cell cycle readouts with ordered pathway inhibitor dissection; single lab\",\n      \"pmids\": [\"20097574\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Matrix metalloproteinases (MMPs) cleave full-length CCL23(1-99) within its unique 32-amino acid extended N-terminus, generating CCL23(26-99) as the principal product. Unlike most CC chemokines where MMP cleavage inactivates, MMP-processed CCL23(26-99) is a stronger agonist in calcium flux assays and Transwell migration assays of CCR1-transfected cells and THP-1 monocytes compared to full-length CCL23. Cleavage sites were identified by MALDI-TOF-MS.\",\n      \"method\": \"Family-wide MMP processing screen, MALDI-TOF-MS cleavage site sequencing, calcium flux assay, Transwell migration assay in CCR1 transfectants and THP-1 cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution of MMP cleavage, MS-confirmed cleavage sites, functional receptor assays\",\n      \"pmids\": [\"22147696\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"CCL23 stimulates chemotaxis of THP-1 monocytes, enhances expression of adhesion molecule CD11c, and promotes release of MMP-2 from monocytes. Proatherogenic stimuli (oxidized LDL, oxidative stress) markedly enhance CCL23 release from THP-1 macrophages.\",\n      \"method\": \"Chemotaxis assay, flow cytometry for CD11c, zymography for MMP-2, ELISA for CCL23 release, RT-PCR for CCL23 in atherosclerotic lesions\",\n      \"journal\": \"Inflammation research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — multiple functional readouts in monocyte/macrophage model; single lab\",\n      \"pmids\": [\"21656154\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Human neutrophils produce and release CCL23 in response to TLR7/8 agonist R848 and, to a lesser extent, LPS, Pam3CSK4, and TNF-α, but not IL-4. On a per-cell basis, R848-activated neutrophils produce more CCL23 than autologous CD14+ monocytes. IFNα negatively modulates CCL23 production by R848-stimulated neutrophils.\",\n      \"method\": \"ELISA for CCL23 protein, RT-PCR/real-time PCR for mRNA, stimulation of purified primary neutrophils and autologous monocytes with multiple TLR agonists and cytokines\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — primary cell comparison between neutrophils and monocytes with multiple stimuli and cytokine modulation\",\n      \"pmids\": [\"28553619\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CCL23 expression in liver cancer cells is transcriptionally regulated by ESR1. Conversely, CCL23 suppresses AKT signaling, which promotes ESR1 expression, forming a feedback loop. CCL23 acting through CCR1 also recruits CD8+ T cell infiltration and inhibits cancer cell proliferation, stemness, and mobility in liver cancer.\",\n      \"method\": \"Bioinformatics screening, RNA-seq, co-immunoprecipitation, AKT pathway western blot, CD8+ T cell infiltration analysis, functional assays (proliferation, stemness, migration) with CCL23 overexpression/knockdown\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — multiple functional assays and mechanistic pathway identification; single lab\",\n      \"pmids\": [\"34050704\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Macrophage-derived CCL23 induces upregulation of immune checkpoint proteins (CTLA-4, TIGIT, TIM-3, LAG-3) on CD8+ T cells, promoting T-cell exhaustion, via phosphorylation of GSK3β in CD8+ T cells.\",\n      \"method\": \"ELISA for CCL23 in ascites, flow cytometry for exhaustion markers, phosphokinase array, Western blot for GSK3β phosphorylation, in vitro CCL23 treatment of CD8+ T cells\",\n      \"journal\": \"British journal of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — phosphokinase array plus western blot validation, flow cytometry of functional outcome; single lab\",\n      \"pmids\": [\"35750747\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CCL23 interacts with transcription factor TFAP4 (demonstrated by co-immunoprecipitation), and overexpression of CCL23 inhibits HCC cell proliferation, invasion, and angiogenesis (tube formation, VEGFA/VEGFR expression) in vitro, while co-expression of TFAP4 blocks these CCL23-mediated inhibitory effects.\",\n      \"method\": \"Co-immunoprecipitation, overexpression plasmid transfection, proliferation assay, invasion assay, HUVEC tube formation assay, RT-qPCR and Western blot\",\n      \"journal\": \"Bioengineered\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — co-IP establishing interaction, multiple functional assays with rescue; single lab\",\n      \"pmids\": [\"35001801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CCL23 inhibits lung leukocyte recruitment in a primate cardiopulmonary bypass model by slowing bone marrow transit of PMNs and monocytes and suppressing their circulatory release and alveolar appearance, without suppressing CD11b/L-selectin expression or post-surgical cytokine levels in BALF.\",\n      \"method\": \"In vivo primate CPB model, BrdU labeling of BM-derived leukocytes, flow cytometry, bronchoalveolar lavage with cytokine ELISA; CCL23 given intravenously\",\n      \"journal\": \"Heart, lung & circulation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo primate model with BrdU tracking and flow cytometry, defined functional phenotype\",\n      \"pmids\": [\"36628657\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The CCL23 gene (MPIF-1/SCYA23) is located on human chromosome 17q11.2, has four exons (unlike the three-exon structure of most CC chemokines), and shares high conservation with neighboring HCC-2 gene (SCYA15) including introns and flanking sequences, indicating recent gene duplication.\",\n      \"method\": \"Large-scale genomic sequencing (random shotgun), gene prediction, EST similarity search\",\n      \"journal\": \"Journal of interferon & cytokine research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — complete genomic sequence determination of a 181 kb region\",\n      \"pmids\": [\"10213461\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CCL23-stimulated THP-1 macrophages exhibit reduced CXCL10 secretion via STAT-3 activation, suggesting CCL23 modulates macrophage cytokine output in the tumor microenvironment.\",\n      \"method\": \"ELISA for CXCL10, in vitro CCL23 peptide stimulation of differentiated THP-1 monocytes, STAT-3 pathway analysis\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single lab, single method with pathway inference; limited mechanistic follow-up\",\n      \"pmids\": [\"41463176\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CCL23 (also known as MPIF-1, CKβ8, or MIP-3) is a monomeric CC chemokine that signals primarily through CCR1 via Gi/Go proteins, activating a cascade involving phospholipase C, PKCδ, NF-κB, ERK1/2, and SAPK/JNK to drive monocyte/leukocyte chemotaxis, cell-cycle progression, and endothelial cell migration; its N-terminal extended proprotein form is proteolytically activated by MMPs to generate a more potent CCR1 agonist (CCL23(26-99)), while inflammatory proteases can also cleave the alternatively spliced isoform CKβ8-1 to release an 18-residue peptide (SHAAGtide) that is a high-potency FPRL1 agonist; CCL23 further promotes angiogenesis by up-regulating MMP-2 and KDR/Flk-1 expression in endothelial cells, and its transcription is regulated by a STAT6-dependent IL-4/IL-13 pathway as well as NFAT, NF-κB, and AP-1 elements in its promoter.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CCL23 is a monomeric CC chemokine that functions as a pleiotropic mediator of leukocyte recruitment, angiogenesis, and immune regulation through signaling primarily via CCR1 and, via proteolytic processing of its alternatively spliced isoform, through FPRL1. Full-length CCL23 contains a unique 32-amino-acid N-terminal extension that is cleaved by matrix metalloproteinases to generate CCL23(26-99), a more potent CCR1 agonist, while inflammatory protease processing of the CKβ8-1 splice variant releases the SHAAGtide peptide, a high-potency FPRL1 agonist for monocyte and neutrophil recruitment [PMID:22147696, PMID:17513790]. CCR1-mediated signaling proceeds through Gi/Go proteins to activate PLC, PKCδ, NF-κB, ERK1/2, and SAPK/JNK, driving monocyte chemotaxis, cell-cycle progression, endothelial migration, MMP-2 upregulation, and KDR/Flk-1-dependent potentiation of VEGF signaling in angiogenesis [PMID:9886417, PMID:19951712, PMID:15927850, PMID:19265684]. CCL23 transcription in monocytes is induced by IL-4/IL-13 through a STAT6-dependent promoter element and by PMA through cooperative NFAT, NF-κB, and AP-1 sites, while in the tumor microenvironment macrophage-derived CCL23 promotes CD8+ T-cell exhaustion via GSK3β phosphorylation [PMID:17371990, PMID:17368823, PMID:35750747].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Identification of CCR1 as the specific receptor and delineation of the Gi-protein–PLC–PLA2 signaling cascade established the core signal transduction pathway underlying CCL23-driven monocyte chemotaxis.\",\n      \"evidence\": \"Radioligand competition binding, calcium flux in CCR1 transfectants and primary monocytes/DCs, pertussis toxin and PLC/PLA2 inhibitor studies\",\n      \"pmids\": [\"9886417\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream transcription factor targets of this cascade were not identified\", \"Relative contributions of PLA2 vs PLC arms to chemotaxis not quantified\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Genomic characterization revealed an atypical four-exon structure and recent duplication origin with HCC-2, while expression profiling showed constitutive CCL23 production by dendritic cells that is suppressed by IFN-γ and CD40 ligation, distinguishing its regulation from other CC chemokines.\",\n      \"evidence\": \"Genomic shotgun sequencing of 17q11.2 region; ELISA and Northern blot of monocyte-derived and CD34+-derived DCs with multiple stimuli\",\n      \"pmids\": [\"10213461\", \"10380905\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional significance of the fourth exon-encoded N-terminal extension was not yet known\", \"Mechanism of CD40L-mediated suppression not defined\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"NMR structure determination showed CCL23 is a monomer with a canonical chemokine fold plus an extra disulfide bond and basic surface patches, providing a structural framework for understanding its extended N-terminus as a proprotein domain and its proteoglycan interactions.\",\n      \"evidence\": \"NMR solution structure with backbone dynamics analysis\",\n      \"pmids\": [\"11060285\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Proteoglycan binding was inferred from surface charge but not directly measured\", \"No co-crystal or NMR structure with CCR1\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Discovery that CCL23 promotes angiogenesis—driving endothelial chemotaxis, tube formation, and in vivo neovascularization through CCR1, with an N-terminally truncated form 100-fold more potent—expanded its role from leukocyte chemoattractant to vascular biology effector.\",\n      \"evidence\": \"Transwell migration, tube formation, chick CAM neovascularization assay with pertussis toxin and anti-CCR1 blockade; structure-activity comparison of truncated vs full-length CCL23\",\n      \"pmids\": [\"15927850\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the endogenous protease responsible for N-terminal truncation in vivo was unknown\", \"Endothelial CCR1 expression levels in different vascular beds not characterized\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"CCL23 was shown to transcriptionally upregulate MMP-2 in endothelial cells and drive MMP-2-dependent Matrigel invasion, linking its angiogenic activity to extracellular matrix remodeling.\",\n      \"evidence\": \"MMP-2 promoter-reporter, RT-PCR, Western blot, Matrigel invasion with MMP inhibitors and neutralizing antibodies\",\n      \"pmids\": [\"16378600\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcription factor mediating MMP-2 promoter activation by CCL23 not identified\", \"No in vivo confirmation of MMP-2 dependence\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Three convergent studies clarified CCL23 transcriptional regulation—STAT6-dependent IL-4/IL-13 induction in monocytes and NFAT/NF-κB/AP-1-dependent PMA induction—and revealed that proteolytic processing of the CKβ8-1 isoform releases SHAAGtide, a uniquely potent FPRL1 agonist for neutrophil and monocyte recruitment.\",\n      \"evidence\": \"Promoter mutagenesis/EMSA for STAT6 and NFAT/NF-κB/AP-1; protease incubation with MS-confirmed cleavage sites, calcium flux, Transwell migration, in vivo leukocyte recruitment\",\n      \"pmids\": [\"17371990\", \"17368823\", \"17513790\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative in vivo contribution of FPRL1 vs CCR1 signaling during inflammation unknown\", \"Nature of the downstream negative cis-element in the STAT6-regulated promoter not fully characterized\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Detailed signaling pathway dissection established that CCL23 activates a Gi/Go → PLC → PKCδ → NF-κB cascade for chemotaxis and proinflammatory gene induction, while a parallel SAPK/JNK pathway mediates KDR/Flk-1 upregulation that potentiates VEGF-driven endothelial proliferation.\",\n      \"evidence\": \"Ordered pharmacological inhibitor studies in chemotaxis and NF-κB assays; KDR promoter-reporter and SAPK/JNK inhibitor studies with downstream ERK phosphorylation readout\",\n      \"pmids\": [\"19951712\", \"19265684\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether PKCδ and SAPK/JNK pathways branch from the same or distinct upstream nodes not resolved\", \"In vivo relevance of KDR upregulation to CCL23-driven angiogenesis not tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"CCL23 was found to drive cell-cycle progression by upregulating cyclins D3 and B1 plus immediate-early genes c-Myc and Egr-1 via the Gi/Go → PLC → PKCδ → ERK1/2 pathway, extending its functional repertoire beyond chemotaxis to proliferative signaling.\",\n      \"evidence\": \"Cell cycle analysis, ERK1/2 phosphorylation, cyclin expression by Western blot, ordered inhibitor dissection\",\n      \"pmids\": [\"20097574\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cell type generality of cell-cycle effects not established beyond the model used\", \"Direct link between ERK1/2 and cyclin D3/B1 transcription not demonstrated\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"A systematic MMP processing screen identified MMPs as the proteases that cleave the extended N-terminus of full-length CCL23(1-99) to generate the more potent CCL23(26-99) agonist, uniquely demonstrating that MMP cleavage activates rather than inactivates a CC chemokine.\",\n      \"evidence\": \"Family-wide in vitro MMP screen, MALDI-TOF-MS cleavage site mapping, calcium flux and Transwell migration in CCR1 transfectants and THP-1 cells\",\n      \"pmids\": [\"22147696\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which specific MMP family members are the physiological activators in vivo remains unclear\", \"Structural basis for enhanced CCR1 agonism of CCL23(26-99) not determined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Neutrophils were identified as a significant cellular source of CCL23, particularly upon TLR7/8 stimulation, with IFNα serving as a negative modulator—broadening the producer cell repertoire beyond monocytes and dendritic cells.\",\n      \"evidence\": \"ELISA and RT-qPCR in purified primary neutrophils vs autologous monocytes with multiple TLR agonists and cytokines\",\n      \"pmids\": [\"28553619\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Receptor and signaling pathway mediating TLR7/8-induced CCL23 transcription in neutrophils not mapped\", \"In vivo contribution of neutrophil-derived CCL23 to inflammation not tested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"In the tumor microenvironment, macrophage-derived CCL23 was shown to promote CD8+ T-cell exhaustion by upregulating CTLA-4, TIGIT, TIM-3, and LAG-3 through GSK3β phosphorylation, establishing a new immunomodulatory axis beyond chemotaxis.\",\n      \"evidence\": \"Phosphokinase array and Western blot for GSK3β in CD8+ T cells, flow cytometry for exhaustion markers, ELISA for CCL23 in ascites\",\n      \"pmids\": [\"35750747\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Receptor on CD8+ T cells mediating GSK3β phosphorylation not identified (CCR1 vs other)\", \"In vivo relevance to tumor immune evasion not confirmed by loss-of-function in animal models\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis for enhanced CCR1 agonism of MMP-processed CCL23, the receptor mediating T-cell exhaustion effects, and the net in vivo balance between CCL23's pro-inflammatory leukocyte recruitment and immunosuppressive T-cell exhaustion functions in disease settings.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No CCL23–CCR1 co-structure available\", \"No genetic loss-of-function model in mammals reported\", \"Relative in vivo roles of CCR1 vs FPRL1 pathways not dissected\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [0, 4, 6, 12]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [3, 6, 12, 14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 6, 9, 14, 16]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 9, 10, 11, 15]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"CCR1\",\n      \"FPRL1\",\n      \"MMP2\",\n      \"TFAP4\",\n      \"ESR1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}