{"gene":"FBXL7","run_date":"2026-06-09T23:54:43","timeline":{"discoveries":[{"year":2012,"finding":"FBXL7 (as SCFFBXL7 E3 ligase complex) mediates polyubiquitination and proteasomal degradation of Aurora A kinase. FBXL7 co-localizes with Aurora A at the centrosome during spindle formation and specifically interacts with Aurora A during mitosis but not interphase. Ectopic FBXL7 expression causes G2/M arrest, tetraploidy, and monopolar/multipolar spindle formation.","method":"Co-immunoprecipitation, co-localization imaging, ectopic expression, cell cycle analysis (flow cytometry)","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP and co-localization with functional phenotype (mitotic arrest), single lab but multiple orthogonal methods","pmids":["22306998"],"is_preprint":false},{"year":2015,"finding":"FBXL7 (as part of the SCF E3 ligase complex) mediates polyubiquitination and proteasomal degradation of survivin. FBXL7 interacts with Glu-126 within survivin's C-terminal α-helix; Lys-90 and Lys-91 within survivin serve as ubiquitin acceptor sites. Fbxl7 overexpression impairs mitochondrial function, and survivin mutants deficient in Fbxl7 interaction (E126A) or ubiquitylation-resistant (KK90RR/KK91RR) rescue mitochondria from Fbxl7-induced damage.","method":"Co-immunoprecipitation, site-directed mutagenesis, in-cell ubiquitylation assay, mitochondrial function assay (CCCP treatment, oxygen consumption)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — includes mutagenesis of both binding site (E126A) and ubiquitin acceptor sites (KK90RR/KK91RR) with functional rescue, multiple orthogonal methods in one study","pmids":["25778398"],"is_preprint":false},{"year":2015,"finding":"The F-box protein Fbxl18 targets Fbxl7 for polyubiquitylation and proteasomal degradation. Lys-109 within Fbxl7 is the essential ubiquitin acceptor site, and an FQ motif within Fbxl7 serves as the molecular recognition site for Fbxl18 interaction. Loss of Fbxl18 or mutation of Fbxl7 at Lys-109 or the FQ motif accentuates Fbxl7-induced apoptosis.","method":"Co-immunoprecipitation, site-directed mutagenesis, in-cell ubiquitylation assay, apoptosis assay (siRNA depletion and ectopic expression)","journal":"Cell death & disease","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis of ubiquitin acceptor site (K109) and binding motif (FQ) with functional apoptosis readout, single lab but multiple orthogonal methods","pmids":["25654763"],"is_preprint":false},{"year":2014,"finding":"Drosophila Fbxl7 binds directly to a specific portion of the Fat protocadherin intracellular domain (ICD), co-localizes with Fat at the proximal edge of cells, and regulates the levels and asymmetric localization of the atypical myosin Dachs at the apical membrane, thereby controlling Hippo signaling and tissue growth. Fbxl7 also regulates trafficking of proteins between the apical membrane and intracellular vesicles.","method":"Genetic loss-of-function (Fbxl7 mutants), co-immunoprecipitation/binding assays, live imaging and co-localization, epistasis with Fat ICD deletion","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis, direct binding demonstrated, co-localization, multiple orthogonal methods; replicated in companion paper (PMID:25256343)","pmids":["25107277"],"is_preprint":false},{"year":2014,"finding":"Drosophila FbxL7 is required to control the level and localization of Dachs and Dachsous downstream of the Fat pathway. GFP-tagged FbxL7 localizes to the plasma membrane in a Fat-dependent manner and is planar polarized. Loss of FbxL7 causes Dachs accumulation (similar to Fat loss); FbxL7 overexpression downregulates Dachs. FbxL7 is proposed to be recruited by Fat to the proximal cell side to restrict Ds and Dachs to the distal side.","method":"Genetic loss-of-function, GFP-tagged protein localization, epistasis with Fat and Dachs, overexpression analysis","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 / Strong — independent replication of PMID:25107277 findings with orthogonal genetic and imaging approaches","pmids":["25256343"],"is_preprint":false},{"year":2020,"finding":"FBXL7 mediates ubiquitylation and proteasomal degradation of active c-SRC after c-SRC phosphorylation at Ser-104. Epigenetic silencing of FBXL7 by promoter hypermethylation in prostate and pancreatic cancers leads to c-SRC accumulation, promoting epithelial-to-mesenchymal transition (EMT) and metastasis. Decitabine (DNA-demethylating agent) restores FBXL7 expression and limits EMT and invasion in a c-SRC-dependent manner.","method":"Co-immunoprecipitation, ubiquitylation assay, site-specific phosphorylation analysis (Ser-104), siRNA knockdown, in vivo tumor/metastasis models, promoter methylation analysis","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods including in vitro ubiquitylation, identification of phospho-Ser-104 as recognition signal, in vivo rescue experiments, functional epistasis with c-SRC inhibitor","pmids":["32839549"],"is_preprint":false},{"year":2023,"finding":"FBXL7 ubiquitinates and degrades PFKFB4 (identified by tandem affinity purification/mass spectrometry), suppressing glucose metabolism. In NSCLC, HIF-1α-induced EZH2 inhibits FBXL7 transcription, thereby stabilizing PFKFB4 and promoting aerobic glycolysis and malignant phenotypes.","method":"Tandem affinity purification coupled with mass spectrometry (TAP/MS), ubiquitylation assay, EZH2 knockdown, HIF-1α pathway analysis, in vitro glucose metabolism assays","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — substrate identified by TAP/MS and functional ubiquitylation confirmed, single lab, upstream epistasis defined by EZH2 knockdown","pmids":["37179372"],"is_preprint":false},{"year":2025,"finding":"PSME3 enhances binding between PTEN and FBXL7 and promotes PTEN degradation through FBXL7-mediated ubiquitination, thereby enhancing glycolysis and OPN secretion in hepatocellular carcinoma cells.","method":"Co-immunoprecipitation, ubiquitylation assay, functional metabolic assays (glycolysis), in vivo experiments","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — co-IP and ubiquitylation assay with functional readout, single lab, single paper","pmids":["41094239"],"is_preprint":false}],"current_model":"FBXL7 is an F-box protein (LRR-containing) that functions as the substrate-recognition subunit of SCF (SKP1-CUL1-F-box) E3 ubiquitin ligase complexes, targeting multiple proteins—including Aurora A (via mitosis-specific interaction at centrosomes), survivin (via Glu-126/Lys-90/91), active c-SRC (after Ser-104 phosphorylation), PFKFB4, and PTEN—for polyubiquitylation and proteasomal degradation, thereby regulating mitotic progression, apoptosis, mitochondrial function, glucose metabolism, and epithelial-to-mesenchymal transition; FBXL7 is itself degraded by SCFFBXL18 (via Lys-109/FQ motif); and in Drosophila its ortholog links the protocadherin Fat to Dachs localization and Hippo pathway signaling."},"narrative":{"mechanistic_narrative":"FBXL7 is the substrate-recognition subunit of an SCF (SKP1–CUL1–F-box) E3 ubiquitin ligase that selects diverse cell-cycle, apoptotic, and metabolic regulators for polyubiquitylation and proteasomal degradation [PMID:25778398, PMID:32839549]. In mitosis it associates with Aurora A kinase at the centrosome during spindle formation and drives its degradation, and ectopic FBXL7 produces G2/M arrest, tetraploidy, and aberrant spindle poles [PMID:22306998]. It also degrades survivin by binding Glu-126 in the survivin C-terminal α-helix and ubiquitylating Lys-90/Lys-91, an activity that impairs mitochondrial function [PMID:25778398]. Substrate recognition is frequently licensed by a modification on the target: FBXL7 captures active c-SRC only after phosphorylation at Ser-104, and loss of FBXL7 by promoter hypermethylation in prostate and pancreatic cancers stabilizes c-SRC to promote EMT and metastasis [PMID:32839549]. Its metabolic substrates include PFKFB4, whose degradation suppresses glycolysis and is relieved when HIF-1α/EZH2 represses FBXL7 transcription in NSCLC, and PTEN, whose FBXL7-mediated degradation is enhanced by PSME3 to drive glycolysis in hepatocellular carcinoma [PMID:37179372, PMID:41094239]. FBXL7 is itself a substrate, being targeted by SCF^FBXL18 through an FQ recognition motif and ubiquitylation at Lys-109, linking its turnover to apoptotic output [PMID:25654763]. In Drosophila, the FBXL7 ortholog binds the Fat protocadherin intracellular domain, localizes to the proximal cell edge in a Fat-dependent manner, and controls the level and planar-polarized localization of the atypical myosin Dachs, thereby tuning Hippo signaling and tissue growth [PMID:25107277, PMID:25256343].","teleology":[{"year":2012,"claim":"Established FBXL7 as a mitotic SCF ligase by identifying Aurora A as a degradation target, answering whether FBXL7 controls cell-cycle progression.","evidence":"Reciprocal co-IP, centrosomal co-localization, and ectopic expression with flow-cytometry cell-cycle analysis in mammalian cells","pmids":["22306998"],"confidence":"Medium","gaps":["Ubiquitin acceptor sites on Aurora A not mapped","Cell-cycle-restricted interaction mechanism not defined","In vitro reconstitution of the ligase complex not shown"]},{"year":2014,"claim":"Defined the Drosophila ortholog as a Fat-pathway effector, showing how FBXL7 couples a protocadherin to Hippo-dependent growth control.","evidence":"Genetic loss-of-function, direct binding to the Fat ICD, GFP localization/planar polarity, and epistasis with Fat and Dachs in two independent studies","pmids":["25107277","25256343"],"confidence":"High","gaps":["Whether Dachs is a direct ubiquitylation substrate not established","Conservation of this Fat/Hippo role in mammals untested","Mechanism of Fat-dependent membrane recruitment not resolved"]},{"year":2015,"claim":"Mapped the survivin recognition and ubiquitylation determinants and linked FBXL7 activity to mitochondrial integrity, resolving how it triggers apoptotic/mitochondrial phenotypes.","evidence":"Co-IP, site-directed mutagenesis (E126A binding site; KK90/91RR acceptor sites), in-cell ubiquitylation, and mitochondrial function assays with functional rescue","pmids":["25778398"],"confidence":"High","gaps":["Connection between survivin degradation and specific mitochondrial pathways incomplete","In vitro reconstitution not performed"]},{"year":2015,"claim":"Showed FBXL7 is itself controlled by ubiquitin-mediated turnover, identifying SCF^FBXL18 as its upstream regulator and connecting FBXL7 levels to apoptosis.","evidence":"Co-IP, mutagenesis of the Lys-109 acceptor site and FQ recognition motif, in-cell ubiquitylation, and apoptosis assays after siRNA/overexpression","pmids":["25654763"],"confidence":"High","gaps":["Physiological signals controlling FBXL18-mediated FBXL7 turnover unknown","Crosstalk with FBXL7's own substrate degradation not defined"]},{"year":2020,"claim":"Demonstrated phosphodegron-based recognition of active c-SRC and connected FBXL7 epigenetic silencing to EMT/metastasis, establishing a tumor-suppressive axis.","evidence":"Co-IP, ubiquitylation assays, Ser-104 phospho-mapping, siRNA, promoter methylation analysis, and in vivo metastasis/rescue models with decitabine","pmids":["32839549"],"confidence":"High","gaps":["Kinase generating the Ser-104 phosphodegron not identified","Generality of phospho-dependent recognition across substrates unclear"]},{"year":2023,"claim":"Extended FBXL7 function to glucose metabolism by identifying PFKFB4 as a substrate within a HIF-1α/EZH2 transcriptional repression circuit.","evidence":"TAP/MS substrate identification, ubiquitylation assays, EZH2 knockdown, HIF-1α pathway and glucose-metabolism assays in NSCLC","pmids":["37179372"],"confidence":"Medium","gaps":["PFKFB4 ubiquitin acceptor sites not mapped","Single-lab substrate validation","Direct ligase reconstitution not shown"]},{"year":2025,"claim":"Added PTEN as an FBXL7 substrate and PSME3 as a binding enhancer, linking FBXL7 activity to glycolysis and OPN secretion in hepatocellular carcinoma.","evidence":"Co-IP, ubiquitylation assays, glycolysis assays, and in vivo experiments in HCC cells","pmids":["41094239"],"confidence":"Medium","gaps":["Mechanism by which PSME3 enhances PTEN–FBXL7 binding undefined","Single co-IP/ubiquitylation study without reciprocal validation","PTEN acceptor sites not mapped"]},{"year":null,"claim":"How FBXL7 substrate selection is coordinated across its many targets and whether its mammalian role in Fat/Hippo-type growth control parallels the Drosophila ortholog remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying model for substrate prioritization among mitotic, apoptotic, and metabolic targets","Mammalian Fat/Hippo connection untested","Structural basis of LRR-substrate recognition not determined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,5,6,7]},{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[0,1,5]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2,3,4]}],"localization":[{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[0]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3,4]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[1,2,5]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[6,7]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,4,5]}],"complexes":["SCF (SKP1-CUL1-F-box) E3 ubiquitin ligase"],"partners":["AURKA","BIRC5","SRC","PFKFB4","PTEN","FBXL18","PSME3","FAT"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UJT9","full_name":"F-box/LRR-repeat protein 7","aliases":["F-box and leucine-rich repeat protein 7","F-box protein FBL6/FBL7"],"length_aa":491,"mass_kda":54.6,"function":"Substrate recognition component of a SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase complex (PubMed:25778398). During mitosis, it mediates the ubiquitination and subsequent proteasomal degradation of AURKA, causing mitotic arrest (By similarity). It also regulates mitochondrial function by mediating the ubiquitination and proteasomal degradation of the apoptosis inhibitor BIRC5 (PubMed:25778398, PubMed:28218735)","subcellular_location":"Cytoplasm, cytoskeleton, microtubule organizing center, centrosome","url":"https://www.uniprot.org/uniprotkb/Q9UJT9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/FBXL7","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/FBXL7","total_profiled":1310},"omim":[{"mim_id":"605656","title":"F-BOX AND LEUCINE-RICH REPEAT PROTEIN 7; FBXL7","url":"https://www.omim.org/entry/605656"},{"mim_id":"600185","title":"BRCA2 DNA REPAIR-ASSOCIATED PROTEIN; BRCA2","url":"https://www.omim.org/entry/600185"},{"mim_id":"235510","title":"HENNEKAM LYMPHANGIECTASIA-LYMPHEDEMA SYNDROME 1; HKLLS1","url":"https://www.omim.org/entry/235510"}],"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/FBXL7"},"hgnc":{"alias_symbol":["KIAA0840","FBL7","FBL6"],"prev_symbol":[]},"alphafold":{"accession":"Q9UJT9","domains":[{"cath_id":"1.20.1280","chopping":"116-153","consensus_level":"medium","plddt":94.6574,"start":116,"end":153}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UJT9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UJT9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UJT9-F1-predicted_aligned_error_v6.png","plddt_mean":81.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=FBXL7","jax_strain_url":"https://www.jax.org/strain/search?query=FBXL7"},"sequence":{"accession":"Q9UJT9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UJT9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UJT9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UJT9"}},"corpus_meta":[{"pmid":"25778398","id":"PMC_25778398","title":"The Proapoptotic F-box Protein Fbxl7 Regulates Mitochondrial Function by Mediating the Ubiquitylation and Proteasomal Degradation of Survivin.","date":"2015","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25778398","citation_count":62,"is_preprint":false},{"pmid":"22306998","id":"PMC_22306998","title":"Novel E3 ligase component FBXL7 ubiquitinates and degrades Aurora A, causing mitotic arrest.","date":"2012","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/22306998","citation_count":47,"is_preprint":false},{"pmid":"25654763","id":"PMC_25654763","title":"F-box protein Fbxl18 mediates polyubiquitylation and proteasomal degradation of the pro-apoptotic SCF subunit Fbxl7.","date":"2015","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/25654763","citation_count":39,"is_preprint":false},{"pmid":"32839549","id":"PMC_32839549","title":"Epigenetic silencing of the ubiquitin ligase subunit FBXL7 impairs c-SRC degradation and promotes epithelial-to-mesenchymal transition and metastasis.","date":"2020","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/32839549","citation_count":39,"is_preprint":false},{"pmid":"25107277","id":"PMC_25107277","title":"The Drosophila F-box protein Fbxl7 binds to the protocadherin fat and regulates Dachs localization and Hippo signaling.","date":"2014","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/25107277","citation_count":39,"is_preprint":false},{"pmid":"25256343","id":"PMC_25256343","title":"The ubiquitin ligase FbxL7 regulates the Dachsous-Fat-Dachs system in Drosophila.","date":"2014","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/25256343","citation_count":36,"is_preprint":false},{"pmid":"32150671","id":"PMC_32150671","title":"miR-152-5p suppresses glioma progression and tumorigenesis and potentiates temozolomide sensitivity by targeting FBXL7.","date":"2020","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32150671","citation_count":19,"is_preprint":false},{"pmid":"37179372","id":"PMC_37179372","title":"Hypoxia-mediated promotion of glucose metabolism in non-small cell lung cancer correlates with activation of the EZH2/FBXL7/PFKFB4 axis.","date":"2023","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/37179372","citation_count":19,"is_preprint":false},{"pmid":"31633297","id":"PMC_31633297","title":"Biallelic mutation of FBXL7 suggests a novel form of Hennekam syndrome.","date":"2019","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/31633297","citation_count":15,"is_preprint":false},{"pmid":"35906197","id":"PMC_35906197","title":"Functional characterization of FBXL7 as a novel player in human cancers.","date":"2022","source":"Cell death discovery","url":"https://pubmed.ncbi.nlm.nih.gov/35906197","citation_count":7,"is_preprint":false},{"pmid":"33235922","id":"PMC_33235922","title":"Epigenetic suppression of FBXL7 promotes metastasis.","date":"2020","source":"Molecular & cellular oncology","url":"https://pubmed.ncbi.nlm.nih.gov/33235922","citation_count":4,"is_preprint":false},{"pmid":"34427826","id":"PMC_34427826","title":"7-Ethoxyrosmanol alleviates hyperglycemia-induced vascular endothelial dysfunction by regulating FBXL7 expression.","date":"2021","source":"Journal of bioenergetics and biomembranes","url":"https://pubmed.ncbi.nlm.nih.gov/34427826","citation_count":4,"is_preprint":false},{"pmid":"37778649","id":"PMC_37778649","title":"Dexmedetomidine mitigates neuroinflammation in an Alzheimer's disease mouse model via the miR-204-3p/FBXL7 signaling axis.","date":"2023","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/37778649","citation_count":4,"is_preprint":false},{"pmid":"35887149","id":"PMC_35887149","title":"FBXL7 Body Hypomethylation Is Frequent in Tumors from the Digestive and Respiratory Tracts and Is Associated with Risk-Factor Exposure.","date":"2022","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/35887149","citation_count":2,"is_preprint":false},{"pmid":"41094239","id":"PMC_41094239","title":"PSME3 drives Tregs infiltration and anti-PD1 resistance in hepatocellular carcinoma by regulating FBXL7/PTEN-mediated metabolic reprogramming.","date":"2025","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/41094239","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8761,"output_tokens":2476,"usd":0.031711,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9550,"output_tokens":3133,"usd":0.063037,"stage2_stop_reason":"end_turn"},"total_usd":0.094748,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2012,\n      \"finding\": \"FBXL7 (as SCFFBXL7 E3 ligase complex) mediates polyubiquitination and proteasomal degradation of Aurora A kinase. FBXL7 co-localizes with Aurora A at the centrosome during spindle formation and specifically interacts with Aurora A during mitosis but not interphase. Ectopic FBXL7 expression causes G2/M arrest, tetraploidy, and monopolar/multipolar spindle formation.\",\n      \"method\": \"Co-immunoprecipitation, co-localization imaging, ectopic expression, cell cycle analysis (flow cytometry)\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP and co-localization with functional phenotype (mitotic arrest), single lab but multiple orthogonal methods\",\n      \"pmids\": [\"22306998\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"FBXL7 (as part of the SCF E3 ligase complex) mediates polyubiquitination and proteasomal degradation of survivin. FBXL7 interacts with Glu-126 within survivin's C-terminal α-helix; Lys-90 and Lys-91 within survivin serve as ubiquitin acceptor sites. Fbxl7 overexpression impairs mitochondrial function, and survivin mutants deficient in Fbxl7 interaction (E126A) or ubiquitylation-resistant (KK90RR/KK91RR) rescue mitochondria from Fbxl7-induced damage.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis, in-cell ubiquitylation assay, mitochondrial function assay (CCCP treatment, oxygen consumption)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — includes mutagenesis of both binding site (E126A) and ubiquitin acceptor sites (KK90RR/KK91RR) with functional rescue, multiple orthogonal methods in one study\",\n      \"pmids\": [\"25778398\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The F-box protein Fbxl18 targets Fbxl7 for polyubiquitylation and proteasomal degradation. Lys-109 within Fbxl7 is the essential ubiquitin acceptor site, and an FQ motif within Fbxl7 serves as the molecular recognition site for Fbxl18 interaction. Loss of Fbxl18 or mutation of Fbxl7 at Lys-109 or the FQ motif accentuates Fbxl7-induced apoptosis.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis, in-cell ubiquitylation assay, apoptosis assay (siRNA depletion and ectopic expression)\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis of ubiquitin acceptor site (K109) and binding motif (FQ) with functional apoptosis readout, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"25654763\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Drosophila Fbxl7 binds directly to a specific portion of the Fat protocadherin intracellular domain (ICD), co-localizes with Fat at the proximal edge of cells, and regulates the levels and asymmetric localization of the atypical myosin Dachs at the apical membrane, thereby controlling Hippo signaling and tissue growth. Fbxl7 also regulates trafficking of proteins between the apical membrane and intracellular vesicles.\",\n      \"method\": \"Genetic loss-of-function (Fbxl7 mutants), co-immunoprecipitation/binding assays, live imaging and co-localization, epistasis with Fat ICD deletion\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis, direct binding demonstrated, co-localization, multiple orthogonal methods; replicated in companion paper (PMID:25256343)\",\n      \"pmids\": [\"25107277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Drosophila FbxL7 is required to control the level and localization of Dachs and Dachsous downstream of the Fat pathway. GFP-tagged FbxL7 localizes to the plasma membrane in a Fat-dependent manner and is planar polarized. Loss of FbxL7 causes Dachs accumulation (similar to Fat loss); FbxL7 overexpression downregulates Dachs. FbxL7 is proposed to be recruited by Fat to the proximal cell side to restrict Ds and Dachs to the distal side.\",\n      \"method\": \"Genetic loss-of-function, GFP-tagged protein localization, epistasis with Fat and Dachs, overexpression analysis\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — independent replication of PMID:25107277 findings with orthogonal genetic and imaging approaches\",\n      \"pmids\": [\"25256343\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"FBXL7 mediates ubiquitylation and proteasomal degradation of active c-SRC after c-SRC phosphorylation at Ser-104. Epigenetic silencing of FBXL7 by promoter hypermethylation in prostate and pancreatic cancers leads to c-SRC accumulation, promoting epithelial-to-mesenchymal transition (EMT) and metastasis. Decitabine (DNA-demethylating agent) restores FBXL7 expression and limits EMT and invasion in a c-SRC-dependent manner.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitylation assay, site-specific phosphorylation analysis (Ser-104), siRNA knockdown, in vivo tumor/metastasis models, promoter methylation analysis\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods including in vitro ubiquitylation, identification of phospho-Ser-104 as recognition signal, in vivo rescue experiments, functional epistasis with c-SRC inhibitor\",\n      \"pmids\": [\"32839549\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FBXL7 ubiquitinates and degrades PFKFB4 (identified by tandem affinity purification/mass spectrometry), suppressing glucose metabolism. In NSCLC, HIF-1α-induced EZH2 inhibits FBXL7 transcription, thereby stabilizing PFKFB4 and promoting aerobic glycolysis and malignant phenotypes.\",\n      \"method\": \"Tandem affinity purification coupled with mass spectrometry (TAP/MS), ubiquitylation assay, EZH2 knockdown, HIF-1α pathway analysis, in vitro glucose metabolism assays\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — substrate identified by TAP/MS and functional ubiquitylation confirmed, single lab, upstream epistasis defined by EZH2 knockdown\",\n      \"pmids\": [\"37179372\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PSME3 enhances binding between PTEN and FBXL7 and promotes PTEN degradation through FBXL7-mediated ubiquitination, thereby enhancing glycolysis and OPN secretion in hepatocellular carcinoma cells.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitylation assay, functional metabolic assays (glycolysis), in vivo experiments\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — co-IP and ubiquitylation assay with functional readout, single lab, single paper\",\n      \"pmids\": [\"41094239\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"FBXL7 is an F-box protein (LRR-containing) that functions as the substrate-recognition subunit of SCF (SKP1-CUL1-F-box) E3 ubiquitin ligase complexes, targeting multiple proteins—including Aurora A (via mitosis-specific interaction at centrosomes), survivin (via Glu-126/Lys-90/91), active c-SRC (after Ser-104 phosphorylation), PFKFB4, and PTEN—for polyubiquitylation and proteasomal degradation, thereby regulating mitotic progression, apoptosis, mitochondrial function, glucose metabolism, and epithelial-to-mesenchymal transition; FBXL7 is itself degraded by SCFFBXL18 (via Lys-109/FQ motif); and in Drosophila its ortholog links the protocadherin Fat to Dachs localization and Hippo pathway signaling.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"FBXL7 is the substrate-recognition subunit of an SCF (SKP1–CUL1–F-box) E3 ubiquitin ligase that selects diverse cell-cycle, apoptotic, and metabolic regulators for polyubiquitylation and proteasomal degradation [#1, #5]. In mitosis it associates with Aurora A kinase at the centrosome during spindle formation and drives its degradation, and ectopic FBXL7 produces G2/M arrest, tetraploidy, and aberrant spindle poles [#0]. It also degrades survivin by binding Glu-126 in the survivin C-terminal α-helix and ubiquitylating Lys-90/Lys-91, an activity that impairs mitochondrial function [#1]. Substrate recognition is frequently licensed by a modification on the target: FBXL7 captures active c-SRC only after phosphorylation at Ser-104, and loss of FBXL7 by promoter hypermethylation in prostate and pancreatic cancers stabilizes c-SRC to promote EMT and metastasis [#5]. Its metabolic substrates include PFKFB4, whose degradation suppresses glycolysis and is relieved when HIF-1α/EZH2 represses FBXL7 transcription in NSCLC, and PTEN, whose FBXL7-mediated degradation is enhanced by PSME3 to drive glycolysis in hepatocellular carcinoma [#6, #7]. FBXL7 is itself a substrate, being targeted by SCF^FBXL18 through an FQ recognition motif and ubiquitylation at Lys-109, linking its turnover to apoptotic output [#2]. In Drosophila, the FBXL7 ortholog binds the Fat protocadherin intracellular domain, localizes to the proximal cell edge in a Fat-dependent manner, and controls the level and planar-polarized localization of the atypical myosin Dachs, thereby tuning Hippo signaling and tissue growth [#3, #4].\",\n  \"teleology\": [\n    {\n      \"year\": 2012,\n      \"claim\": \"Established FBXL7 as a mitotic SCF ligase by identifying Aurora A as a degradation target, answering whether FBXL7 controls cell-cycle progression.\",\n      \"evidence\": \"Reciprocal co-IP, centrosomal co-localization, and ectopic expression with flow-cytometry cell-cycle analysis in mammalian cells\",\n      \"pmids\": [\"22306998\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ubiquitin acceptor sites on Aurora A not mapped\", \"Cell-cycle-restricted interaction mechanism not defined\", \"In vitro reconstitution of the ligase complex not shown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined the Drosophila ortholog as a Fat-pathway effector, showing how FBXL7 couples a protocadherin to Hippo-dependent growth control.\",\n      \"evidence\": \"Genetic loss-of-function, direct binding to the Fat ICD, GFP localization/planar polarity, and epistasis with Fat and Dachs in two independent studies\",\n      \"pmids\": [\"25107277\", \"25256343\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Dachs is a direct ubiquitylation substrate not established\", \"Conservation of this Fat/Hippo role in mammals untested\", \"Mechanism of Fat-dependent membrane recruitment not resolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Mapped the survivin recognition and ubiquitylation determinants and linked FBXL7 activity to mitochondrial integrity, resolving how it triggers apoptotic/mitochondrial phenotypes.\",\n      \"evidence\": \"Co-IP, site-directed mutagenesis (E126A binding site; KK90/91RR acceptor sites), in-cell ubiquitylation, and mitochondrial function assays with functional rescue\",\n      \"pmids\": [\"25778398\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Connection between survivin degradation and specific mitochondrial pathways incomplete\", \"In vitro reconstitution not performed\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showed FBXL7 is itself controlled by ubiquitin-mediated turnover, identifying SCF^FBXL18 as its upstream regulator and connecting FBXL7 levels to apoptosis.\",\n      \"evidence\": \"Co-IP, mutagenesis of the Lys-109 acceptor site and FQ recognition motif, in-cell ubiquitylation, and apoptosis assays after siRNA/overexpression\",\n      \"pmids\": [\"25654763\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological signals controlling FBXL18-mediated FBXL7 turnover unknown\", \"Crosstalk with FBXL7's own substrate degradation not defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Demonstrated phosphodegron-based recognition of active c-SRC and connected FBXL7 epigenetic silencing to EMT/metastasis, establishing a tumor-suppressive axis.\",\n      \"evidence\": \"Co-IP, ubiquitylation assays, Ser-104 phospho-mapping, siRNA, promoter methylation analysis, and in vivo metastasis/rescue models with decitabine\",\n      \"pmids\": [\"32839549\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase generating the Ser-104 phosphodegron not identified\", \"Generality of phospho-dependent recognition across substrates unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended FBXL7 function to glucose metabolism by identifying PFKFB4 as a substrate within a HIF-1α/EZH2 transcriptional repression circuit.\",\n      \"evidence\": \"TAP/MS substrate identification, ubiquitylation assays, EZH2 knockdown, HIF-1α pathway and glucose-metabolism assays in NSCLC\",\n      \"pmids\": [\"37179372\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"PFKFB4 ubiquitin acceptor sites not mapped\", \"Single-lab substrate validation\", \"Direct ligase reconstitution not shown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Added PTEN as an FBXL7 substrate and PSME3 as a binding enhancer, linking FBXL7 activity to glycolysis and OPN secretion in hepatocellular carcinoma.\",\n      \"evidence\": \"Co-IP, ubiquitylation assays, glycolysis assays, and in vivo experiments in HCC cells\",\n      \"pmids\": [\"41094239\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which PSME3 enhances PTEN–FBXL7 binding undefined\", \"Single co-IP/ubiquitylation study without reciprocal validation\", \"PTEN acceptor sites not mapped\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How FBXL7 substrate selection is coordinated across its many targets and whether its mammalian role in Fat/Hippo-type growth control parallels the Drosophila ortholog remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying model for substrate prioritization among mitotic, apoptotic, and metabolic targets\", \"Mammalian Fat/Hippo connection untested\", \"Structural basis of LRR-substrate recognition not determined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 5, 6, 7]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2, 3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [1, 2, 5]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [6, 7]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 4, 5]}\n    ],\n    \"complexes\": [\"SCF (SKP1-CUL1-F-box) E3 ubiquitin ligase\"],\n    \"partners\": [\"AURKA\", \"BIRC5\", \"SRC\", \"PFKFB4\", \"PTEN\", \"FBXL18\", \"PSME3\", \"Fat\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}