{"gene":"CCBE1","run_date":"2026-04-28T17:28:52","timeline":{"discoveries":[{"year":2014,"finding":"CCBE1 promotes proteolytic cleavage of the poorly active 29/31-kDa pro-VEGF-C by ADAMTS3, generating the mature 21/23-kDa VEGF-C that induces increased VEGFR signaling. CCBE1 itself does not process VEGF-C but enhances ADAMTS3-mediated cleavage.","method":"Cell-based VEGF-C processing assay (CCBE1-transfected cells), in vivo AAV-mediated co-transduction in mouse muscle, receptor signaling readouts","journal":"Circulation","confidence":"High","confidence_rationale":"Tier 1–2 — biochemical processing assay with defined substrate and enzyme, replicated in vivo, foundational mechanism paper with 186 citations","pmids":["24552833"],"is_preprint":false},{"year":2014,"finding":"Genetic epistasis in zebrafish shows ccbe1 acts within the Vegfc/Vegfr3 pathway: Vegfc-driven phenotypes are suppressed in ccbe1 mutants, Vegfc-driven sprouting is enhanced by local Ccbe1 overexpression, Vegfc/Vegfr3-dependent ERK signaling is impaired without Ccbe1, and overexpression of mature VEGFC rescues ccbe1 loss-of-function phenotypes.","method":"Zebrafish genetic epistasis (double mutants, overexpression rescue), ERK signaling assays, in vitro VEGFC processing assay","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal genetic and biochemical methods, 139 citations, independently consistent with parallel studies","pmids":["24523457"],"is_preprint":false},{"year":2011,"finding":"CCBE1 is required for budding and migration of Prox1+ lymphatic endothelial cells from the cardinal vein in mice; CCBE1 protein binds extracellular matrix components in vitro and strongly enhances VEGF-C-mediated lymphangiogenesis in a corneal micropocket assay, but has little lymphangiogenic effect alone.","method":"Ccbe1 knockout mouse phenotypic analysis, in vitro ECM binding assay, corneal micropocket lymphangiogenesis assay, proximity ligation assay for VEGFR3 activation","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 2 — KO mouse with defined cellular phenotype plus in vitro binding and in vivo functional assay, 168 citations","pmids":["21778431"],"is_preprint":false},{"year":2015,"finding":"The collagen repeat domain of CCBE1 is essential for VEGF-C processing and lymphangiogenesis: CCBE1ΔCollagen mice fully phenocopy CCBE1 knockout and fail to activate VEGFC in vitro, whereas CCBE1ΔEGF retains ability to activate VEGFC processing in vitro and partially supports lymphangiogenesis in vivo.","method":"Knock-in mice expressing domain deletion mutants, in vivo zebrafish rescue assays, in vitro VEGFC processing assay","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 1–2 — domain mutagenesis in vivo (knock-in mice) and in vitro processing assay, multiple orthogonal approaches","pmids":["25814692"],"is_preprint":false},{"year":2017,"finding":"The N-terminal EGF-like domain of CCBE1 colocalizes pro-VEGF-C with ADAMTS3 at the lymphatic endothelial cell surface, facilitating proteolytic activation; when ADAMTS3 is limiting, only the N-terminal domain (not the C-terminal collagen domain) supports VEGF-C processing. A disease-associated ADAMTS3 mutation causes abnormal CCBE1 localization.","method":"Domain-deletion recombinant proteins in cell-based VEGFC processing assay, colocalization microscopy, transgenic mouse model for VEGF-C C-terminal domain requirement","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro reconstitution with domain mutants plus in vivo transgenic validation, mechanistically orthogonal to collagen domain findings","pmids":["28687807"],"is_preprint":false},{"year":2013,"finding":"E2F7 and E2F8 directly bind and transcriptionally activate the CCBE1 promoter; inactivation of e2f7/8 in zebrafish impairs venous sprouting and lymphangiogenesis with reduced ccbe1 expression, and overexpression of e2f7/8 rescues Ccbe1-dependent phenotypes.","method":"Genome-wide E2F binding (ChIP), promoter reporter assays, zebrafish e2f7/8 loss-of-function and rescue experiments","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP plus in vivo genetic rescue, single lab","pmids":["24069224"],"is_preprint":false},{"year":2013,"finding":"CCBE1 is required cell-nonautonomously for fetal liver definitive erythropoiesis; loss of CCBE1 reduces erythroblastic island formation due to abnormal macrophage function, without affecting erythropoietin or stem cell factor expression. Postnatal CCBE1 deletion does not impair erythropoiesis.","method":"Ccbe1 null mouse embryo analysis, conditional hematopoietic cell-specific deletion, colony-forming assays, hematopoietic reconstitution, erythroblastic island formation assay","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal approaches in KO and conditional KO mice with defined cellular mechanism, Strong evidence from multiple methods","pmids":["23426945"],"is_preprint":false},{"year":2020,"finding":"TGFβ signaling downregulates CCBE1 transcription in cancer-associated fibroblasts and CRC cells through direct binding of SMADs to the CCBE1 gene locus, reducing VEGF-C maturation and lymphangiogenesis.","method":"Chromatin immunoprecipitation (ChIP) for SMAD binding to CCBE1 locus, qPCR, western blot, in vitro HLEC tube formation and migration, in vivo hindfoot lymphatic metastasis model","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP plus functional in vitro and in vivo assays, single lab","pmids":["32089745"],"is_preprint":false},{"year":2023,"finding":"YAP/TAZ-TEAD4 complexes transcriptionally upregulate CCBE1 by directly binding to the enhancer region of CCBE1 in CRC cells and cancer-associated fibroblasts, resulting in enhanced VEGFC proteolysis and lymphangiogenesis. BET inhibitor JQ1 inhibits CCBE1 transcription and suppresses VEGFC proteolysis.","method":"ChIP for TEAD4 binding at CCBE1 enhancer, in vitro HLEC tube formation, in vivo xenograft lymphangiogenesis model, JQ1 pharmacological inhibition","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP plus functional in vitro and in vivo assays, single lab","pmids":["36781122"],"is_preprint":false},{"year":2023,"finding":"CCBE1 inhibits mitochondrial fission by preventing DRP1 phosphorylation at Ser616 through direct binding to TGFβR2 to inhibit TGFβ signaling, thereby promoting mitochondrial fusion in HCC cells.","method":"Recombinant CCBE1 protein treatment, CCBE1 overexpression, co-immunoprecipitation (binding to TGFβR2), DRP1 phosphorylation assay, mitochondrial morphology analysis, in vitro and in vivo tumor models","journal":"Matrix biology : journal of the International Society for Matrix Biology","confidence":"Medium","confidence_rationale":"Tier 2–3 — Co-IP plus functional phosphorylation and mitochondrial morphology readouts, single lab","pmids":["36849082"],"is_preprint":false},{"year":2023,"finding":"SP1 phosphorylation at Ser101 drives CCBE1 transcription in TMZ-resistant GBM; CCBE1 secretion depends on binding to CAVIN1. CCBE1 promotes VEGFC maturation and activates VEGFR2/VEGFR3/Rho signaling in vascular endothelial cells to induce hyper-angiogenesis in TMZ-resistant tumors.","method":"In vivo and in vitro gain/loss of function, co-immunoprecipitation (CAVIN1-CCBE1 binding), signaling pathway analysis, HCMEC/d3 endothelial cell functional assays","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP for CAVIN1-CCBE1 interaction plus functional assays, single lab","pmids":["38092144"],"is_preprint":false},{"year":2022,"finding":"Copper stress epigenetically suppresses ccbe1 expression via hypermethylation of E2F7/8 binding sites on the ccbe1 promoter, reducing E2F7/8 binding enrichment and contributing to lymphangiogenesis defects in zebrafish embryos.","method":"ChIP for E2F7/8 binding at ccbe1 promoter, methylation analysis, zebrafish embryo model, mammalian cell assays","journal":"Angiogenesis","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP with functional zebrafish model, single lab, mechanistically consistent with prior E2F7/8 findings","pmids":["35034208"],"is_preprint":false},{"year":2022,"finding":"Loss of CCBE1 in the epicardium leads to congenital heart defects including thinner and hyper-trabeculated ventricular myocardium, reduced cardiomyocyte and epicardial cell proliferation, reduced epicardial-derived cell migration, and deregulation of EMT-related genes.","method":"Ccbe1 knockout mouse model, epicardial explant outgrowth assay, RNA-seq, immunostaining, qRT-PCR","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 — KO mouse with defined cellular phenotype and transcriptomic validation, single lab","pmids":["36293499"],"is_preprint":false},{"year":2023,"finding":"Inducible deletion of CCBE1 in adult mice impairs postnatal development of meningeal lymphatics and decreases macromolecule drainage to deep cervical lymph nodes; adult CCBE1 deletion causes regression of established meningeal lymphatic structures.","method":"Inducible conditional CCBE1 knockout mouse, meningeal lymphatic structural analysis, macromolecule drainage assay","journal":"Biomedicine & pharmacotherapy","confidence":"Medium","confidence_rationale":"Tier 2 — conditional KO with defined lymphatic structural and functional phenotype, single lab","pmids":["38141283"],"is_preprint":false},{"year":2018,"finding":"CCBE1 knockdown by shRNA or blockade with a neutralizing antibody impairs differentiation of mouse embryonic stem cells along the cardiac mesoderm lineage, resulting in decreased mature cardiomyocyte marker expression and smaller embryoid bodies.","method":"shRNA knockdown, neutralizing antibody blockade in mouse ESC differentiation, cardiomyocyte marker expression analysis","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — two orthogonal loss-of-function approaches with defined differentiation phenotype, single lab","pmids":["30281646"],"is_preprint":false},{"year":2025,"finding":"CCBE1 knockdown in HUVECs reduces mitochondrial reactive oxygen species and mitochondrial mass, and shifts cells into a metabolically elevated state with increased ATP production, respiration, and glycolysis, without affecting proliferation or permeability.","method":"siRNA knockdown in HUVECs, multi-colour flow cytometry for mROS and mitochondrial mass, Seahorse metabolic assay","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 — preprint, single lab, single loss-of-function approach with metabolic readouts","pmids":["bio_10.1101_2025.08.18.670989"],"is_preprint":true}],"current_model":"CCBE1 is a secreted extracellular matrix protein that acts as a co-factor for ADAMTS3-mediated proteolytic activation of pro-VEGF-C into its mature form: its C-terminal collagen domain enhances ADAMTS3 cleavage activity while its N-terminal EGF-like domain colocalizes pro-VEGF-C and ADAMTS3 at the lymphatic endothelial cell surface, together driving VEGFR3 signaling and lymphangiogenesis; additionally, CCBE1 plays roles in fetal liver erythropoiesis (via macrophage-dependent erythroblastic island formation), epicardial and cardiac progenitor development, meningeal lymphatic maintenance, and mitochondrial dynamics (by binding TGFβR2 to inhibit DRP1-Ser616 phosphorylation and fission), while its transcription is positively regulated by E2F7/8 and YAP/TAZ-TEAD4 and negatively regulated by TGFβ-SMAD signaling."},"narrative":{"teleology":[{"year":2011,"claim":"Establishing that CCBE1 is required for lymphatic endothelial cell budding and acts as a potentiator rather than independent driver of VEGF-C-induced lymphangiogenesis resolved the question of whether CCBE1 functions autonomously or as a co-factor in lymphatic development.","evidence":"Ccbe1 knockout mouse analysis combined with corneal micropocket lymphangiogenesis assay and ECM binding assay","pmids":["21778431"],"confidence":"High","gaps":["The molecular target through which CCBE1 enhances VEGF-C activity was unknown","Whether CCBE1 acts on VEGF-C directly or on its receptor was not resolved","ECM binding partners were not identified"]},{"year":2013,"claim":"Discovery that E2F7/8 directly bind and activate the CCBE1 promoter established the first transcriptional regulatory axis for CCBE1 expression in lymphangiogenesis, while identification of CCBE1's role in fetal erythropoiesis revealed a lymphangiogenesis-independent function.","evidence":"ChIP for E2F binding at CCBE1 promoter with zebrafish genetic rescue; Ccbe1 null and conditional KO mice with erythroblastic island formation assays","pmids":["24069224","23426945"],"confidence":"High","gaps":["Whether E2F7/8 regulation is conserved in mammals was not confirmed","The macrophage-intrinsic mechanism by which CCBE1 supports erythroblastic island formation was undefined","Whether erythropoietic and lymphangiogenic functions share a common molecular pathway was unknown"]},{"year":2014,"claim":"Demonstrating that CCBE1 enhances ADAMTS3-mediated proteolytic processing of pro-VEGF-C into mature VEGF-C identified the precise biochemical mechanism by which CCBE1 drives VEGFR3 signaling and lymphangiogenesis.","evidence":"Cell-based VEGF-C processing assays with defined enzyme and substrate, AAV co-transduction in mouse muscle, and zebrafish genetic epistasis with ERK signaling readouts","pmids":["24552833","24523457"],"confidence":"High","gaps":["Which structural domain of CCBE1 was required for enhancing ADAMTS3 activity was not yet determined","Whether CCBE1 directly contacts ADAMTS3 or pro-VEGF-C was unresolved"]},{"year":2015,"claim":"Domain dissection revealed that the collagen repeat domain is essential for VEGF-C processing and lymphangiogenesis in vivo, while the EGF-like domain is partially dispensable, establishing a domain-specific functional hierarchy.","evidence":"Knock-in mice expressing CCBE1 domain deletions combined with zebrafish rescue and in vitro processing assays","pmids":["25814692"],"confidence":"High","gaps":["The role of the EGF-like domain under limiting ADAMTS3 conditions was not yet appreciated","Structural basis for how the collagen domain enhances ADAMTS3 catalysis was not determined"]},{"year":2017,"claim":"Showing that the N-terminal EGF-like domain colocalizes pro-VEGF-C with ADAMTS3 at the cell surface—and becomes critical when ADAMTS3 is limiting—resolved the apparent contradiction with collagen domain essentiality and established a bipartite activation model.","evidence":"Domain-deletion recombinant proteins in cell-based processing assays with colocalization microscopy and transgenic mouse validation","pmids":["28687807"],"confidence":"High","gaps":["Direct binding affinities between CCBE1 domains and ADAMTS3/VEGF-C were not measured","No structural model of the ternary complex exists"]},{"year":2018,"claim":"Demonstrating that CCBE1 loss impairs cardiac mesoderm differentiation from embryonic stem cells extended CCBE1's developmental roles beyond lymphangiogenesis and erythropoiesis.","evidence":"shRNA knockdown and neutralizing antibody blockade during mouse ESC differentiation with cardiomyocyte marker analysis","pmids":["30281646"],"confidence":"Medium","gaps":["The signaling pathway mediating CCBE1's role in cardiomyocyte differentiation was not identified","Whether this reflects a VEGF-C-dependent or independent mechanism was not tested"]},{"year":2020,"claim":"Identification of TGFβ-SMAD-mediated transcriptional repression of CCBE1 revealed a negative regulatory axis that modulates VEGF-C maturation in the tumor microenvironment.","evidence":"ChIP for SMAD binding at CCBE1 locus, HLEC tube formation, hindfoot lymphatic metastasis model","pmids":["32089745"],"confidence":"Medium","gaps":["Whether TGFβ regulation of CCBE1 operates outside of cancer contexts was not tested","Relative contribution of SMAD-mediated repression versus E2F-mediated activation in vivo was not determined"]},{"year":2022,"claim":"Demonstrating that copper stress suppresses CCBE1 via hypermethylation of E2F7/8 binding sites provided an epigenetic layer of regulation, while epicardial CCBE1 knockout revealed its requirement for ventricular myocardium compaction and epicardial EMT.","evidence":"ChIP and methylation analysis of ccbe1 promoter in zebrafish; Ccbe1 KO mouse epicardial explant assays and RNA-seq","pmids":["35034208","36293499"],"confidence":"Medium","gaps":["Whether the epicardial phenotype involves VEGF-C processing or a distinct pathway was not resolved","Relevance of copper-induced epigenetic regulation to human disease was not established"]},{"year":2023,"claim":"Multiple studies expanded CCBE1 biology: YAP/TAZ-TEAD4 was identified as a positive transcriptional regulator; CCBE1 was shown to bind TGFβR2 and inhibit DRP1-Ser616 phosphorylation to suppress mitochondrial fission; adult CCBE1 deletion caused meningeal lymphatic regression; and CAVIN1 was identified as a secretion partner.","evidence":"ChIP for TEAD4 at CCBE1 enhancer; Co-IP of CCBE1-TGFβR2 with DRP1 phosphorylation and mitochondrial morphology analysis; inducible conditional KO with meningeal lymphatic imaging; Co-IP of CCBE1-CAVIN1 with endothelial signaling assays","pmids":["36781122","36849082","38141283","38092144"],"confidence":"Medium","gaps":["The TGFβR2-DRP1 axis has not been validated outside hepatocellular carcinoma cells","Whether meningeal lymphatic maintenance requires VEGF-C processing or another CCBE1 function is unknown","CAVIN1-dependent secretion mechanism needs independent confirmation","Structural basis for CCBE1-TGFβR2 interaction is not established"]},{"year":null,"claim":"Key unresolved questions include the structural basis of the CCBE1-ADAMTS3-VEGF-C ternary complex, whether CCBE1's non-lymphangiogenic roles (erythropoiesis, cardiac development, mitochondrial dynamics) proceed through VEGF-C-dependent or independent mechanisms, and the physiological significance of CCBE1's metabolic effects on endothelial cells.","evidence":"","pmids":[],"confidence":"Low","gaps":["No crystal or cryo-EM structure of CCBE1 or its complexes exists","VEGF-C dependence of erythropoietic and cardiac phenotypes is untested","Endothelial metabolic effects are only from a single preprint"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,3,4]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[0,2,4]},{"term_id":"GO:0031012","term_label":"extracellular matrix","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[2,6,12,14]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,4,9]},{"term_id":"R-HSA-1474244","term_label":"Extracellular matrix organization","supporting_discovery_ids":[2]}],"complexes":[],"partners":["ADAMTS3","VEGFC","TGFBR2","CAVIN1"],"other_free_text":[]},"mechanistic_narrative":"CCBE1 is a secreted extracellular matrix protein that functions as an essential co-factor for VEGF-C maturation and lymphangiogenesis, with additional roles in erythropoiesis, cardiac development, and meningeal lymphatic maintenance. Its collagen repeat domain enhances ADAMTS3-mediated proteolytic cleavage of pro-VEGF-C into the mature form that activates VEGFR3 signaling, while its N-terminal EGF-like domain colocalizes pro-VEGF-C and ADAMTS3 at the lymphatic endothelial cell surface to facilitate processing [PMID:24552833, PMID:25814692, PMID:28687807]. Beyond lymphangiogenesis, CCBE1 is required cell-nonautonomously for fetal liver erythroblastic island formation through macrophage function [PMID:23426945], supports epicardial cell migration and ventricular myocardium development [PMID:36293499], and maintains meningeal lymphatic integrity in adults [PMID:38141283]. CCBE1 transcription is positively regulated by E2F7/8 and YAP/TAZ-TEAD4 and negatively regulated by TGFβ-SMAD signaling [PMID:24069224, PMID:36781122, PMID:32089745]."},"prefetch_data":{"uniprot":{"accession":"Q6UXH8","full_name":"Collagen and calcium-binding EGF domain-containing protein 1","aliases":["Full of fluid protein homolog"],"length_aa":406,"mass_kda":44.1,"function":"Required for lymphangioblast budding and angiogenic sprouting from venous endothelium during embryogenesis","subcellular_location":"Secreted","url":"https://www.uniprot.org/uniprotkb/Q6UXH8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CCBE1","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CCBE1","total_profiled":1310},"omim":[{"mim_id":"616843","title":"LYMPHATIC MALFORMATION 6; LMPHM6","url":"https://www.omim.org/entry/616843"},{"mim_id":"612753","title":"COLLAGEN AND CALCIUM-BINDING EGF DOMAIN-CONTAINING PROTEIN 1; CCBE1","url":"https://www.omim.org/entry/612753"},{"mim_id":"611184","title":"PIEZO-TYPE MECHANOSENSITIVE ION CHANNEL COMPONENT 1; PIEZO1","url":"https://www.omim.org/entry/611184"},{"mim_id":"235510","title":"HENNEKAM LYMPHANGIECTASIA-LYMPHEDEMA SYNDROME 1; HKLLS1","url":"https://www.omim.org/entry/235510"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"ovary","ntpm":25.6}],"url":"https://www.proteinatlas.org/search/CCBE1"},"hgnc":{"alias_symbol":["FLJ30681","KIAA1983"],"prev_symbol":[]},"alphafold":{"accession":"Q6UXH8","domains":[{"cath_id":"-","chopping":"49-90","consensus_level":"medium","plddt":83.4938,"start":49,"end":90},{"cath_id":"2.10.25,2.10.25","chopping":"92-135","consensus_level":"medium","plddt":86.6175,"start":92,"end":135},{"cath_id":"2.10.25.10","chopping":"143-180","consensus_level":"medium","plddt":84.9237,"start":143,"end":180}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6UXH8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q6UXH8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q6UXH8-F1-predicted_aligned_error_v6.png","plddt_mean":64.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CCBE1","jax_strain_url":"https://www.jax.org/strain/search?query=CCBE1"},"sequence":{"accession":"Q6UXH8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q6UXH8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q6UXH8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6UXH8"}},"corpus_meta":[{"pmid":"19935664","id":"PMC_19935664","title":"Mutations in CCBE1 cause generalized lymph vessel dysplasia in humans.","date":"2009","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19935664","citation_count":215,"is_preprint":false},{"pmid":"24552833","id":"PMC_24552833","title":"CCBE1 enhances lymphangiogenesis via A disintegrin and metalloprotease with thrombospondin motifs-3-mediated vascular endothelial growth factor-C activation.","date":"2014","source":"Circulation","url":"https://pubmed.ncbi.nlm.nih.gov/24552833","citation_count":186,"is_preprint":false},{"pmid":"21778431","id":"PMC_21778431","title":"CCBE1 is essential for mammalian lymphatic vascular development and enhances the lymphangiogenic effect of vascular endothelial growth factor-C in vivo.","date":"2011","source":"Circulation research","url":"https://pubmed.ncbi.nlm.nih.gov/21778431","citation_count":168,"is_preprint":false},{"pmid":"24523457","id":"PMC_24523457","title":"Ccbe1 regulates Vegfc-mediated induction of Vegfr3 signaling during embryonic 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manifesting lymphedema-cholestasis syndrome, and the other, fetal hydrops.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24086631","citation_count":25,"is_preprint":false},{"pmid":"35034208","id":"PMC_35034208","title":"Copper stress impairs angiogenesis and lymphangiogenesis during zebrafish embryogenesis by down-regulating pERK1/2-foxm1-MMP2/9 axis and epigenetically regulating ccbe1 expression.","date":"2022","source":"Angiogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/35034208","citation_count":23,"is_preprint":false},{"pmid":"22252499","id":"PMC_22252499","title":"Ccbe1 expression marks the cardiac and lymphatic progenitor lineages during early stages of mouse development.","date":"2011","source":"The International journal of developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/22252499","citation_count":19,"is_preprint":false},{"pmid":"38092144","id":"PMC_38092144","title":"Neovascularization directed by CAVIN1/CCBE1/VEGFC confers 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sciences","url":"https://pubmed.ncbi.nlm.nih.gov/36293499","citation_count":7,"is_preprint":false},{"pmid":"35222551","id":"PMC_35222551","title":"CCBE1 in Cardiac Development and Disease.","date":"2022","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35222551","citation_count":6,"is_preprint":false},{"pmid":"38141283","id":"PMC_38141283","title":"CCBE1 regulates the development and prevents the age-dependent regression of meningeal lymphatics.","date":"2023","source":"Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie","url":"https://pubmed.ncbi.nlm.nih.gov/38141283","citation_count":6,"is_preprint":false},{"pmid":"30281646","id":"PMC_30281646","title":"Loss of Ccbe1 affects cardiac-specification and cardiomyocyte differentiation in mouse embryonic stem cells.","date":"2018","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/30281646","citation_count":6,"is_preprint":false},{"pmid":"34234628","id":"PMC_34234628","title":"Predicting the Most Deleterious Missense Nonsynonymous Single-Nucleotide Polymorphisms of Hennekam Syndrome-Causing CCBE1 Gene, In Silico Analysis.","date":"2021","source":"TheScientificWorldJournal","url":"https://pubmed.ncbi.nlm.nih.gov/34234628","citation_count":6,"is_preprint":false},{"pmid":"28073151","id":"PMC_28073151","title":"CCBE1 mutation causing sclerosing cholangitis: Expanding the spectrum of lymphedema-cholestasis syndrome.","date":"2017","source":"Hepatology (Baltimore, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/28073151","citation_count":5,"is_preprint":false},{"pmid":"34819004","id":"PMC_34819004","title":"The Lymphangiogenic Factor CCBE1 Promotes Angiogenesis and Tumor Growth in Colorectal Cancer.","date":"2022","source":"Current molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/34819004","citation_count":4,"is_preprint":false},{"pmid":"34931668","id":"PMC_34931668","title":"Hsa_circ_0076931 suppresses malignant biological properties, down-regulates miR-6760-3p through direct binding, and up-regulates CCBE1 in glioma.","date":"2022","source":"Bioscience reports","url":"https://pubmed.ncbi.nlm.nih.gov/34931668","citation_count":3,"is_preprint":false},{"pmid":"36583660","id":"PMC_36583660","title":"LncRNA DNAJC3-AS1 promotes the biological functions of papillary thyroid carcinoma via regulating the microRNA-27a-3p/CCBE1 axis.","date":"2022","source":"Cell biology international","url":"https://pubmed.ncbi.nlm.nih.gov/36583660","citation_count":2,"is_preprint":false},{"pmid":"30165116","id":"PMC_30165116","title":"Full-length human CCBE1 production and purification: leveraging bioprocess development for high quality glycosylation attributes and functionality.","date":"2018","source":"Journal of biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/30165116","citation_count":2,"is_preprint":false},{"pmid":"32629717","id":"PMC_32629717","title":"Intestinal lymphangiectasia in a 3-month-old girl: A case report of Hennekam syndrome caused by CCBE1 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Colony-Forming Cell Transcriptomic Profiling in CT-defined Coronary Artery Disease from the BioHEART-CT Study Implicate CCBE1 in Mitochondrial Dysfunction-associated Atherosclerosis","date":"2025-08-22","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.18.670989","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.02.18.638907","title":"Single-nuclear transcriptomics of lymphedema-associated adipose reveals a pro-lymphangiogenic stromal cell population","date":"2025-02-19","source":"bioRxiv","url":"https://doi.org/10.1101/2025.02.18.638907","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":22457,"output_tokens":3911,"usd":0.063018},"stage2":{"model":"claude-opus-4-6","input_tokens":7364,"output_tokens":2768,"usd":0.15903},"total_usd":0.222048,"stage1_batch_id":"msgbatch_011kfMfE81o6CTcyhVUqumuW","stage2_batch_id":"msgbatch_01DTputS6WNkH745x1nVSoBo","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2014,\n      \"finding\": \"CCBE1 promotes proteolytic cleavage of the poorly active 29/31-kDa pro-VEGF-C by ADAMTS3, generating the mature 21/23-kDa VEGF-C that induces increased VEGFR signaling. CCBE1 itself does not process VEGF-C but enhances ADAMTS3-mediated cleavage.\",\n      \"method\": \"Cell-based VEGF-C processing assay (CCBE1-transfected cells), in vivo AAV-mediated co-transduction in mouse muscle, receptor signaling readouts\",\n      \"journal\": \"Circulation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — biochemical processing assay with defined substrate and enzyme, replicated in vivo, foundational mechanism paper with 186 citations\",\n      \"pmids\": [\"24552833\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Genetic epistasis in zebrafish shows ccbe1 acts within the Vegfc/Vegfr3 pathway: Vegfc-driven phenotypes are suppressed in ccbe1 mutants, Vegfc-driven sprouting is enhanced by local Ccbe1 overexpression, Vegfc/Vegfr3-dependent ERK signaling is impaired without Ccbe1, and overexpression of mature VEGFC rescues ccbe1 loss-of-function phenotypes.\",\n      \"method\": \"Zebrafish genetic epistasis (double mutants, overexpression rescue), ERK signaling assays, in vitro VEGFC processing assay\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal genetic and biochemical methods, 139 citations, independently consistent with parallel studies\",\n      \"pmids\": [\"24523457\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"CCBE1 is required for budding and migration of Prox1+ lymphatic endothelial cells from the cardinal vein in mice; CCBE1 protein binds extracellular matrix components in vitro and strongly enhances VEGF-C-mediated lymphangiogenesis in a corneal micropocket assay, but has little lymphangiogenic effect alone.\",\n      \"method\": \"Ccbe1 knockout mouse phenotypic analysis, in vitro ECM binding assay, corneal micropocket lymphangiogenesis assay, proximity ligation assay for VEGFR3 activation\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO mouse with defined cellular phenotype plus in vitro binding and in vivo functional assay, 168 citations\",\n      \"pmids\": [\"21778431\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The collagen repeat domain of CCBE1 is essential for VEGF-C processing and lymphangiogenesis: CCBE1ΔCollagen mice fully phenocopy CCBE1 knockout and fail to activate VEGFC in vitro, whereas CCBE1ΔEGF retains ability to activate VEGFC processing in vitro and partially supports lymphangiogenesis in vivo.\",\n      \"method\": \"Knock-in mice expressing domain deletion mutants, in vivo zebrafish rescue assays, in vitro VEGFC processing assay\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — domain mutagenesis in vivo (knock-in mice) and in vitro processing assay, multiple orthogonal approaches\",\n      \"pmids\": [\"25814692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The N-terminal EGF-like domain of CCBE1 colocalizes pro-VEGF-C with ADAMTS3 at the lymphatic endothelial cell surface, facilitating proteolytic activation; when ADAMTS3 is limiting, only the N-terminal domain (not the C-terminal collagen domain) supports VEGF-C processing. A disease-associated ADAMTS3 mutation causes abnormal CCBE1 localization.\",\n      \"method\": \"Domain-deletion recombinant proteins in cell-based VEGFC processing assay, colocalization microscopy, transgenic mouse model for VEGF-C C-terminal domain requirement\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro reconstitution with domain mutants plus in vivo transgenic validation, mechanistically orthogonal to collagen domain findings\",\n      \"pmids\": [\"28687807\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"E2F7 and E2F8 directly bind and transcriptionally activate the CCBE1 promoter; inactivation of e2f7/8 in zebrafish impairs venous sprouting and lymphangiogenesis with reduced ccbe1 expression, and overexpression of e2f7/8 rescues Ccbe1-dependent phenotypes.\",\n      \"method\": \"Genome-wide E2F binding (ChIP), promoter reporter assays, zebrafish e2f7/8 loss-of-function and rescue experiments\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP plus in vivo genetic rescue, single lab\",\n      \"pmids\": [\"24069224\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"CCBE1 is required cell-nonautonomously for fetal liver definitive erythropoiesis; loss of CCBE1 reduces erythroblastic island formation due to abnormal macrophage function, without affecting erythropoietin or stem cell factor expression. Postnatal CCBE1 deletion does not impair erythropoiesis.\",\n      \"method\": \"Ccbe1 null mouse embryo analysis, conditional hematopoietic cell-specific deletion, colony-forming assays, hematopoietic reconstitution, erythroblastic island formation assay\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal approaches in KO and conditional KO mice with defined cellular mechanism, Strong evidence from multiple methods\",\n      \"pmids\": [\"23426945\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TGFβ signaling downregulates CCBE1 transcription in cancer-associated fibroblasts and CRC cells through direct binding of SMADs to the CCBE1 gene locus, reducing VEGF-C maturation and lymphangiogenesis.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) for SMAD binding to CCBE1 locus, qPCR, western blot, in vitro HLEC tube formation and migration, in vivo hindfoot lymphatic metastasis model\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP plus functional in vitro and in vivo assays, single lab\",\n      \"pmids\": [\"32089745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"YAP/TAZ-TEAD4 complexes transcriptionally upregulate CCBE1 by directly binding to the enhancer region of CCBE1 in CRC cells and cancer-associated fibroblasts, resulting in enhanced VEGFC proteolysis and lymphangiogenesis. BET inhibitor JQ1 inhibits CCBE1 transcription and suppresses VEGFC proteolysis.\",\n      \"method\": \"ChIP for TEAD4 binding at CCBE1 enhancer, in vitro HLEC tube formation, in vivo xenograft lymphangiogenesis model, JQ1 pharmacological inhibition\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP plus functional in vitro and in vivo assays, single lab\",\n      \"pmids\": [\"36781122\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CCBE1 inhibits mitochondrial fission by preventing DRP1 phosphorylation at Ser616 through direct binding to TGFβR2 to inhibit TGFβ signaling, thereby promoting mitochondrial fusion in HCC cells.\",\n      \"method\": \"Recombinant CCBE1 protein treatment, CCBE1 overexpression, co-immunoprecipitation (binding to TGFβR2), DRP1 phosphorylation assay, mitochondrial morphology analysis, in vitro and in vivo tumor models\",\n      \"journal\": \"Matrix biology : journal of the International Society for Matrix Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — Co-IP plus functional phosphorylation and mitochondrial morphology readouts, single lab\",\n      \"pmids\": [\"36849082\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SP1 phosphorylation at Ser101 drives CCBE1 transcription in TMZ-resistant GBM; CCBE1 secretion depends on binding to CAVIN1. CCBE1 promotes VEGFC maturation and activates VEGFR2/VEGFR3/Rho signaling in vascular endothelial cells to induce hyper-angiogenesis in TMZ-resistant tumors.\",\n      \"method\": \"In vivo and in vitro gain/loss of function, co-immunoprecipitation (CAVIN1-CCBE1 binding), signaling pathway analysis, HCMEC/d3 endothelial cell functional assays\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP for CAVIN1-CCBE1 interaction plus functional assays, single lab\",\n      \"pmids\": [\"38092144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Copper stress epigenetically suppresses ccbe1 expression via hypermethylation of E2F7/8 binding sites on the ccbe1 promoter, reducing E2F7/8 binding enrichment and contributing to lymphangiogenesis defects in zebrafish embryos.\",\n      \"method\": \"ChIP for E2F7/8 binding at ccbe1 promoter, methylation analysis, zebrafish embryo model, mammalian cell assays\",\n      \"journal\": \"Angiogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP with functional zebrafish model, single lab, mechanistically consistent with prior E2F7/8 findings\",\n      \"pmids\": [\"35034208\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Loss of CCBE1 in the epicardium leads to congenital heart defects including thinner and hyper-trabeculated ventricular myocardium, reduced cardiomyocyte and epicardial cell proliferation, reduced epicardial-derived cell migration, and deregulation of EMT-related genes.\",\n      \"method\": \"Ccbe1 knockout mouse model, epicardial explant outgrowth assay, RNA-seq, immunostaining, qRT-PCR\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO mouse with defined cellular phenotype and transcriptomic validation, single lab\",\n      \"pmids\": [\"36293499\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Inducible deletion of CCBE1 in adult mice impairs postnatal development of meningeal lymphatics and decreases macromolecule drainage to deep cervical lymph nodes; adult CCBE1 deletion causes regression of established meningeal lymphatic structures.\",\n      \"method\": \"Inducible conditional CCBE1 knockout mouse, meningeal lymphatic structural analysis, macromolecule drainage assay\",\n      \"journal\": \"Biomedicine & pharmacotherapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — conditional KO with defined lymphatic structural and functional phenotype, single lab\",\n      \"pmids\": [\"38141283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CCBE1 knockdown by shRNA or blockade with a neutralizing antibody impairs differentiation of mouse embryonic stem cells along the cardiac mesoderm lineage, resulting in decreased mature cardiomyocyte marker expression and smaller embryoid bodies.\",\n      \"method\": \"shRNA knockdown, neutralizing antibody blockade in mouse ESC differentiation, cardiomyocyte marker expression analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — two orthogonal loss-of-function approaches with defined differentiation phenotype, single lab\",\n      \"pmids\": [\"30281646\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CCBE1 knockdown in HUVECs reduces mitochondrial reactive oxygen species and mitochondrial mass, and shifts cells into a metabolically elevated state with increased ATP production, respiration, and glycolysis, without affecting proliferation or permeability.\",\n      \"method\": \"siRNA knockdown in HUVECs, multi-colour flow cytometry for mROS and mitochondrial mass, Seahorse metabolic assay\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — preprint, single lab, single loss-of-function approach with metabolic readouts\",\n      \"pmids\": [\"bio_10.1101_2025.08.18.670989\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"CCBE1 is a secreted extracellular matrix protein that acts as a co-factor for ADAMTS3-mediated proteolytic activation of pro-VEGF-C into its mature form: its C-terminal collagen domain enhances ADAMTS3 cleavage activity while its N-terminal EGF-like domain colocalizes pro-VEGF-C and ADAMTS3 at the lymphatic endothelial cell surface, together driving VEGFR3 signaling and lymphangiogenesis; additionally, CCBE1 plays roles in fetal liver erythropoiesis (via macrophage-dependent erythroblastic island formation), epicardial and cardiac progenitor development, meningeal lymphatic maintenance, and mitochondrial dynamics (by binding TGFβR2 to inhibit DRP1-Ser616 phosphorylation and fission), while its transcription is positively regulated by E2F7/8 and YAP/TAZ-TEAD4 and negatively regulated by TGFβ-SMAD signaling.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CCBE1 is a secreted extracellular matrix protein that functions as an essential co-factor for VEGF-C maturation and lymphangiogenesis, with additional roles in erythropoiesis, cardiac development, and meningeal lymphatic maintenance. Its collagen repeat domain enhances ADAMTS3-mediated proteolytic cleavage of pro-VEGF-C into the mature form that activates VEGFR3 signaling, while its N-terminal EGF-like domain colocalizes pro-VEGF-C and ADAMTS3 at the lymphatic endothelial cell surface to facilitate processing [PMID:24552833, PMID:25814692, PMID:28687807]. Beyond lymphangiogenesis, CCBE1 is required cell-nonautonomously for fetal liver erythroblastic island formation through macrophage function [PMID:23426945], supports epicardial cell migration and ventricular myocardium development [PMID:36293499], and maintains meningeal lymphatic integrity in adults [PMID:38141283]. CCBE1 transcription is positively regulated by E2F7/8 and YAP/TAZ-TEAD4 and negatively regulated by TGFβ-SMAD signaling [PMID:24069224, PMID:36781122, PMID:32089745].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Establishing that CCBE1 is required for lymphatic endothelial cell budding and acts as a potentiator rather than independent driver of VEGF-C-induced lymphangiogenesis resolved the question of whether CCBE1 functions autonomously or as a co-factor in lymphatic development.\",\n      \"evidence\": \"Ccbe1 knockout mouse analysis combined with corneal micropocket lymphangiogenesis assay and ECM binding assay\",\n      \"pmids\": [\"21778431\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The molecular target through which CCBE1 enhances VEGF-C activity was unknown\", \"Whether CCBE1 acts on VEGF-C directly or on its receptor was not resolved\", \"ECM binding partners were not identified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Discovery that E2F7/8 directly bind and activate the CCBE1 promoter established the first transcriptional regulatory axis for CCBE1 expression in lymphangiogenesis, while identification of CCBE1's role in fetal erythropoiesis revealed a lymphangiogenesis-independent function.\",\n      \"evidence\": \"ChIP for E2F binding at CCBE1 promoter with zebrafish genetic rescue; Ccbe1 null and conditional KO mice with erythroblastic island formation assays\",\n      \"pmids\": [\"24069224\", \"23426945\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether E2F7/8 regulation is conserved in mammals was not confirmed\", \"The macrophage-intrinsic mechanism by which CCBE1 supports erythroblastic island formation was undefined\", \"Whether erythropoietic and lymphangiogenic functions share a common molecular pathway was unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrating that CCBE1 enhances ADAMTS3-mediated proteolytic processing of pro-VEGF-C into mature VEGF-C identified the precise biochemical mechanism by which CCBE1 drives VEGFR3 signaling and lymphangiogenesis.\",\n      \"evidence\": \"Cell-based VEGF-C processing assays with defined enzyme and substrate, AAV co-transduction in mouse muscle, and zebrafish genetic epistasis with ERK signaling readouts\",\n      \"pmids\": [\"24552833\", \"24523457\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which structural domain of CCBE1 was required for enhancing ADAMTS3 activity was not yet determined\", \"Whether CCBE1 directly contacts ADAMTS3 or pro-VEGF-C was unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Domain dissection revealed that the collagen repeat domain is essential for VEGF-C processing and lymphangiogenesis in vivo, while the EGF-like domain is partially dispensable, establishing a domain-specific functional hierarchy.\",\n      \"evidence\": \"Knock-in mice expressing CCBE1 domain deletions combined with zebrafish rescue and in vitro processing assays\",\n      \"pmids\": [\"25814692\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The role of the EGF-like domain under limiting ADAMTS3 conditions was not yet appreciated\", \"Structural basis for how the collagen domain enhances ADAMTS3 catalysis was not determined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showing that the N-terminal EGF-like domain colocalizes pro-VEGF-C with ADAMTS3 at the cell surface—and becomes critical when ADAMTS3 is limiting—resolved the apparent contradiction with collagen domain essentiality and established a bipartite activation model.\",\n      \"evidence\": \"Domain-deletion recombinant proteins in cell-based processing assays with colocalization microscopy and transgenic mouse validation\",\n      \"pmids\": [\"28687807\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct binding affinities between CCBE1 domains and ADAMTS3/VEGF-C were not measured\", \"No structural model of the ternary complex exists\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrating that CCBE1 loss impairs cardiac mesoderm differentiation from embryonic stem cells extended CCBE1's developmental roles beyond lymphangiogenesis and erythropoiesis.\",\n      \"evidence\": \"shRNA knockdown and neutralizing antibody blockade during mouse ESC differentiation with cardiomyocyte marker analysis\",\n      \"pmids\": [\"30281646\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The signaling pathway mediating CCBE1's role in cardiomyocyte differentiation was not identified\", \"Whether this reflects a VEGF-C-dependent or independent mechanism was not tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identification of TGFβ-SMAD-mediated transcriptional repression of CCBE1 revealed a negative regulatory axis that modulates VEGF-C maturation in the tumor microenvironment.\",\n      \"evidence\": \"ChIP for SMAD binding at CCBE1 locus, HLEC tube formation, hindfoot lymphatic metastasis model\",\n      \"pmids\": [\"32089745\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether TGFβ regulation of CCBE1 operates outside of cancer contexts was not tested\", \"Relative contribution of SMAD-mediated repression versus E2F-mediated activation in vivo was not determined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrating that copper stress suppresses CCBE1 via hypermethylation of E2F7/8 binding sites provided an epigenetic layer of regulation, while epicardial CCBE1 knockout revealed its requirement for ventricular myocardium compaction and epicardial EMT.\",\n      \"evidence\": \"ChIP and methylation analysis of ccbe1 promoter in zebrafish; Ccbe1 KO mouse epicardial explant assays and RNA-seq\",\n      \"pmids\": [\"35034208\", \"36293499\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the epicardial phenotype involves VEGF-C processing or a distinct pathway was not resolved\", \"Relevance of copper-induced epigenetic regulation to human disease was not established\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Multiple studies expanded CCBE1 biology: YAP/TAZ-TEAD4 was identified as a positive transcriptional regulator; CCBE1 was shown to bind TGFβR2 and inhibit DRP1-Ser616 phosphorylation to suppress mitochondrial fission; adult CCBE1 deletion caused meningeal lymphatic regression; and CAVIN1 was identified as a secretion partner.\",\n      \"evidence\": \"ChIP for TEAD4 at CCBE1 enhancer; Co-IP of CCBE1-TGFβR2 with DRP1 phosphorylation and mitochondrial morphology analysis; inducible conditional KO with meningeal lymphatic imaging; Co-IP of CCBE1-CAVIN1 with endothelial signaling assays\",\n      \"pmids\": [\"36781122\", \"36849082\", \"38141283\", \"38092144\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The TGFβR2-DRP1 axis has not been validated outside hepatocellular carcinoma cells\", \"Whether meningeal lymphatic maintenance requires VEGF-C processing or another CCBE1 function is unknown\", \"CAVIN1-dependent secretion mechanism needs independent confirmation\", \"Structural basis for CCBE1-TGFβR2 interaction is not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis of the CCBE1-ADAMTS3-VEGF-C ternary complex, whether CCBE1's non-lymphangiogenic roles (erythropoiesis, cardiac development, mitochondrial dynamics) proceed through VEGF-C-dependent or independent mechanisms, and the physiological significance of CCBE1's metabolic effects on endothelial cells.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No crystal or cryo-EM structure of CCBE1 or its complexes exists\", \"VEGF-C dependence of erythropoietic and cardiac phenotypes is untested\", \"Endothelial metabolic effects are only from a single preprint\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 2, 4]},\n      {\"term_id\": \"GO:0031012\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [2, 6, 12, 14]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 4, 9]},\n      {\"term_id\": \"R-HSA-1474244\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"ADAMTS3\",\n      \"VEGFC\",\n      \"TGFBR2\",\n      \"CAVIN1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}