{"gene":"FLOT1","run_date":"2026-06-09T23:54:43","timeline":{"discoveries":[{"year":2011,"finding":"Knockdown of FLOT1 in breast cancer cells suppressed Akt activity, enhanced transcriptional activity of FOXO3a, upregulated CDK inhibitors p21(Cip1) and p27(Kip1), and downregulated cyclin D1, establishing FLOT1 as a promoter of proliferation via the Akt-FOXO3a-cell cycle axis.","method":"siRNA knockdown, Western blotting, luciferase reporter assay, in vitro and in vivo proliferation/tumorigenicity assays","journal":"Clinical Cancer Research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KD with defined cellular phenotype and two orthogonal mechanistic readouts (Western blot + luciferase reporter), single lab","pmids":["21447726"],"is_preprint":false},{"year":2017,"finding":"FLOT1 co-immunoprecipitates with syndecan-1 (but not caveolin-1) in liver cells; C-TRL binding to syndecan-1 enhances this association; the two molecules traffic together into lysosomes. The interaction requires the transmembrane/cytoplasmic region of syndecan-1 and the N-terminal hydrophobic domain of FLOT1. FLOT1 knockdown substantially inhibited syndecan-1 endocytosis. Adenoviral re-expression of wild-type FLOT1 (but not a mutant lacking the N-terminal hydrophobic domain) normalized plasma triglycerides in T2DM mice, demonstrating that FLOT1 mediates syndecan-1-dependent disposal of remnant lipoproteins.","method":"Co-immunoprecipitation, domain-deletion mutagenesis, siRNA knockdown in cultured liver cells, adenoviral overexpression in T2DM mice, plasma triglyceride/retinyl ester assays","journal":"Arteriosclerosis, Thrombosis, and Vascular Biology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — reciprocal Co-IP, domain mutagenesis with functional rescue in vivo, multiple orthogonal methods in single rigorous study","pmids":["29162604"],"is_preprint":false},{"year":2019,"finding":"FLOT1 overexpression or knockdown in lung adenocarcinoma cells respectively activates or suppresses the Erk/Akt signaling pathway, promoting epithelial-mesenchymal transition and cell cycle progression, establishing FLOT1 as an upstream regulator of Erk/Akt in LUAD.","method":"Lentiviral knockdown and overexpression, Western blotting for EMT and cell cycle markers, Erk/Akt pathway analysis","journal":"Thoracic Cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD and OE models with defined pathway readout, single lab, two orthogonal approaches (KD + OE)","pmids":["30838797"],"is_preprint":false},{"year":2023,"finding":"FLOT1 interacts with BCAR1 (breast cancer anti-estrogen resistance 1), regulates BCAR1 phosphorylation and translocation, and promotes gastric cancer cell proliferation, migration, and invasion via ERK signaling. Re-expression of wild-type but not Y410F-mutant BCAR1 partially restored migration/invasion after FLOT1 knockdown, and an ERK inhibitor blocked this rescue.","method":"Co-immunoprecipitation, BCAR1 knockdown epistasis, site-directed mutagenesis (Y410F), ERK inhibitor treatment, cell migration/invasion assays","journal":"International Journal of Biological Sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, mutagenesis, and epistasis in single lab; multiple orthogonal methods","pmids":["37928269"],"is_preprint":false},{"year":2023,"finding":"After irradiation, SDC1 carries TGM2 from the cell membrane into the cytoplasm and transports it to lysosomes by binding to FLOT1; TGM2 then recognizes BHMT on autophagosomes to coordinate autophagosome-lysosome fusion. This SDC1-TGM2-FLOT1-BHMT complex maintains autophagic flux and enhances radioresistance of glioblastoma.","method":"Co-immunoprecipitation, immunofluorescence, mRFP-GFP-LC3 autophagy flux assay, transmission electron microscopy, colony formation, flow cytometry","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP demonstrating complex formation, autophagy flux assay, TEM, single lab with multiple orthogonal methods","pmids":["37441590"],"is_preprint":false},{"year":2023,"finding":"EIF4A3 physically interacts with FLOT1 in lung adenocarcinoma cells (identified by mass spectrometry), positively regulates FLOT1 protein expression, and FLOT1 knockdown reverses EIF4A3-overexpression-induced activation of the PI3K-AKT-ERK1/2-P70S6K pathway and autophagy, placing FLOT1 downstream of EIF4A3 in this signaling cascade.","method":"Mass spectrometry co-immunoprecipitation, siRNA knockdown epistasis, Western blotting for pathway components, transcriptome sequencing","journal":"Molecular Cancer Research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MS-based interaction identification plus epistasis rescue, single lab","pmids":["37011005"],"is_preprint":false},{"year":2023,"finding":"FLOT1 knockdown in AML cells triggers both apoptosis and pyroptosis, while FLOT1 overexpression promotes cell growth and apoptosis resistance, establishing FLOT1 as a regulator of cell death pathways in AML.","method":"siRNA knockdown, overexpression, flow cytometry for apoptosis/pyroptosis, in vivo xenograft engraftment assay","journal":"Annals of Hematology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD and OE with defined cell-death phenotypes, in vivo validation, single lab","pmids":["36697954"],"is_preprint":false},{"year":2025,"finding":"SMARCC1 activates FLOT1 transcription by binding to the FLOT1 promoter (identified by ChIP), and FLOT1 downstream promotes M2 macrophage polarization and reduces ferroptosis (maintaining GSH:GSSG ratio, reducing lipid peroxidation) in lung cancer; FLOT1 overexpression rescues the inhibitory effects of SMARCC1 knockdown on macrophage polarization and ferroptosis resistance.","method":"Chromatin immunoprecipitation (ChIP), siRNA knockdown, overexpression rescue, GSH:GSSG ratio measurement, lipid peroxidation assay, transmission electron microscopy, xenograft models, co-culture assays","journal":"Journal of Molecular Medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP establishes direct transcriptional activation, functional rescue with multiple orthogonal readouts, single lab","pmids":["40108025"],"is_preprint":false},{"year":2025,"finding":"m6A modification of FLOT1 mRNA is significantly elevated in ovarian cancer cells compared to normal ovarian epithelial cells, leading to increased FLOT1 mRNA expression; treatment with the methylation inhibitor 3-deazaadenosine decreases FLOT1 mRNA expression and suppresses tumor formation in xenograft mice.","method":"m6A modification analysis, qRT-PCR, methylation inhibitor treatment, xenograft tumor model","journal":"Cell Biology International","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, m6A measurement without identification of specific writer/eraser, pharmacological inhibition not targeting specific machinery","pmids":["40066501"],"is_preprint":false},{"year":2026,"finding":"FLOT1 interacts with the transcription factor FOSL2 (confirmed by Co-IP), and this complex upregulates EphA2 transcription (confirmed by ChIP and dual-luciferase assay), activating the p38/MAPK signaling pathway to drive pro-inflammatory microglial polarization in Alzheimer's disease models; FLOT1 silencing in APP/PS1 mice reduced neuroinflammatory markers and improved spatial memory.","method":"Co-immunoprecipitation, chromatin immunoprecipitation, dual-luciferase reporter assay, siRNA knockdown, APP/PS1 mouse model, Morris water maze","journal":"Neuropharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ChIP, and luciferase assay with in vivo validation, single lab, multiple orthogonal methods","pmids":["41548752"],"is_preprint":false},{"year":2026,"finding":"FLOT1 localizes to circular dorsal ruffles (CDRs) in podocytes and is required for CDR-derived macropinosome formation; depletion of FLOT1 impairs growth-factor-stimulated mTORC1 activation, demonstrating that FLOT1 links macropinocytosis to nutrient sensing and mTORC1 activity in podocytes.","method":"Imaging/immunostaining for CDR localization, Flot1 knockout cells, macropinosome formation assay, biochemical mTORC1 activation assay, cell growth measurement","journal":"Cell Structure and Function","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO model with defined localization and functional readout (mTORC1 activation), multiple orthogonal methods, single lab","pmids":["41500583"],"is_preprint":false}],"current_model":"FLOT1 is a lipid raft scaffold protein that mediates clathrin-independent endocytosis (including syndecan-1-dependent remnant lipoprotein uptake via its N-terminal hydrophobic domain), participates in autophagosome-lysosome fusion as part of an SDC1-TGM2-FLOT1-BHMT complex, promotes mTORC1 activation by supporting macropinosome formation, regulates cancer cell survival and proliferation through Akt/ERK signaling (partly via interactions with BCAR1 and downstream of EIF4A3), drives pro-inflammatory microglial polarization by interacting with FOSL2 to upregulate EphA2/p38-MAPK, and is itself transcriptionally activated by SMARCC1 and post-transcriptionally regulated by m6A modification and multiple miRNAs."},"narrative":{"mechanistic_narrative":"FLOT1 is a membrane-associated scaffold protein that organizes clathrin-independent endocytic and macropinocytic membrane trafficking and couples these events to growth, survival, and inflammatory signaling [PMID:29162604, PMID:41500583]. Through its N-terminal hydrophobic domain it binds the transmembrane/cytoplasmic region of syndecan-1 to drive syndecan-1-dependent endocytosis and lysosomal disposal of remnant lipoproteins, a function whose loss raises plasma triglycerides and is rescued by wild-type but not N-terminal-deletion FLOT1 in vivo [PMID:29162604]. FLOT1 is required for circular dorsal ruffle-derived macropinosome formation and for growth-factor-stimulated mTORC1 activation, linking membrane uptake to nutrient sensing [PMID:41500583], and it participates in an SDC1-TGM2-FLOT1-BHMT assembly that delivers TGM2 to lysosomes to coordinate autophagosome-lysosome fusion and sustain autophagic flux [PMID:37441590]. In cancer cells FLOT1 acts as an upstream driver of Akt/ERK signaling, promoting proliferation, cell-cycle progression, and epithelial-mesenchymal transition: it suppresses FOXO3a-dependent induction of p21 and p27 while sustaining cyclin D1 [PMID:21447726, PMID:30838797], interacts with BCAR1 to regulate its phosphorylation and ERK-dependent migration and invasion [PMID:37928269], operates downstream of EIF4A3 in a PI3K-AKT-ERK-P70S6K cascade [PMID:37011005], and controls apoptosis and pyroptosis sensitivity [PMID:36697954]. FLOT1 expression is induced transcriptionally by SMARCC1, downstream of which it promotes M2 macrophage polarization and ferroptosis resistance [PMID:40108025], and in microglia FLOT1 complexes with the transcription factor FOSL2 to upregulate EphA2 and activate p38/MAPK-driven pro-inflammatory polarization in Alzheimer's disease models [PMID:41548752].","teleology":[{"year":2011,"claim":"Established that FLOT1 is not merely a structural raft marker but actively promotes proliferation, by defining the Akt-FOXO3a-cell cycle axis it controls.","evidence":"siRNA knockdown with Western blot, luciferase reporter, and in vivo tumorigenicity in breast cancer cells","pmids":["21447726"],"confidence":"Medium","gaps":["Does not show how FLOT1 mechanistically engages Akt","No direct binding partner linking FLOT1 to Akt identified"]},{"year":2017,"claim":"Defined a specific molecular mechanism for FLOT1 in endocytosis by mapping its N-terminal hydrophobic domain to the syndecan-1 cytoplasmic region and demonstrating physiological rescue of lipoprotein clearance in vivo.","evidence":"Reciprocal Co-IP, domain-deletion mutagenesis, knockdown in liver cells, and adenoviral rescue with triglyceride assays in T2DM mice","pmids":["29162604"],"confidence":"High","gaps":["Does not resolve whether caveolin-independent uptake is general or syndecan-1-specific","Structural basis of the hydrophobic-domain interaction not determined"]},{"year":2019,"claim":"Generalized FLOT1's role as an upstream activator of Erk/Akt beyond breast cancer, linking it to EMT and cell-cycle progression in lung adenocarcinoma.","evidence":"Lentiviral knockdown and overexpression with Western blotting of EMT/cell-cycle and pathway markers","pmids":["30838797"],"confidence":"Medium","gaps":["Mechanism connecting FLOT1 to Erk/Akt activation not defined","No direct molecular intermediary identified"]},{"year":2023,"claim":"Identified direct protein partners and upstream regulators that channel FLOT1 into ERK/PI3K signaling, moving from correlation to molecular epistasis.","evidence":"Co-IP and mass-spectrometry interaction (BCAR1; EIF4A3), site-directed mutagenesis (BCAR1 Y410F), and knockdown rescue with pathway inhibitors in gastric and lung cancer cells","pmids":["37928269","37011005"],"confidence":"Medium","gaps":["Whether BCAR1 and EIF4A3 act in the same or parallel pathways is unresolved","No reciprocal validation across independent labs"]},{"year":2023,"claim":"Extended FLOT1's trafficking function to autophagy, placing it in a defined SDC1-TGM2-FLOT1-BHMT complex that couples lysosomal cargo delivery to autophagosome fusion and radioresistance.","evidence":"Co-IP, immunofluorescence, mRFP-GFP-LC3 flux assay, and TEM in glioblastoma cells","pmids":["37441590"],"confidence":"Medium","gaps":["Direct binding interfaces within the four-member complex not mapped","Stoichiometry and assembly order beyond Co-IP unestablished"]},{"year":2023,"claim":"Showed FLOT1 controls cell-death decisions, regulating both apoptosis and pyroptosis in addition to proliferation.","evidence":"Knockdown/overexpression with flow cytometry and xenograft engraftment in AML cells","pmids":["36697954"],"confidence":"Medium","gaps":["Molecular link between FLOT1 and pyroptotic machinery not identified","Whether death regulation is downstream of its known signaling roles is unclear"]},{"year":2025,"claim":"Identified upstream transcriptional control of FLOT1 (SMARCC1) and post-transcriptional control (m6A), and linked FLOT1 to immune polarization and ferroptosis resistance.","evidence":"ChIP, knockdown/overexpression rescue, GSH:GSSG and lipid peroxidation assays (SMARCC1); m6A analysis with methylation inhibitor and xenografts (ovarian)","pmids":["40108025","40066501"],"confidence":"Medium","gaps":["Specific m6A writer/eraser for FLOT1 mRNA not identified","Mechanism by which FLOT1 suppresses ferroptosis not defined"]},{"year":2026,"claim":"Defined non-cancer functions: FLOT1 drives macropinocytosis-coupled mTORC1 activation in podocytes and complexes with FOSL2 to drive neuroinflammatory microglial polarization in Alzheimer's models.","evidence":"Flot1 knockout cells with macropinosome and mTORC1 assays (podocytes); Co-IP, ChIP, luciferase, and APP/PS1 mouse behavior (microglia)","pmids":["41500583","41548752"],"confidence":"Medium","gaps":["How macropinosome-localized FLOT1 transmits the signal to mTORC1 is not resolved","Whether the FOSL2 interaction is direct or scaffolded is not established"]},{"year":null,"claim":"Whether FLOT1's diverse signaling roles (Akt/ERK, mTORC1, autophagy, inflammation) all derive from a single core function in raft-based membrane trafficking, or represent independent scaffold activities, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of FLOT1 in any of its complexes","No unifying biochemical mechanism connecting its endocytic and transcription-associated roles"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,3,4,9]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[1]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,10]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[1,4]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[10]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[1,10]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,2,3,5]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[4]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[6]}],"complexes":["SDC1-TGM2-FLOT1-BHMT complex","FLOT1-FOSL2 complex"],"partners":["SDC1","BCAR1","TGM2","EIF4A3","FOSL2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O75955","full_name":"Flotillin-1","aliases":[],"length_aa":427,"mass_kda":47.4,"function":"May act as a scaffolding protein within caveolar membranes, functionally participating in formation of caveolae or caveolae-like vesicles","subcellular_location":"Cell membrane; Endosome; Membrane, caveola; Melanosome; Membrane raft","url":"https://www.uniprot.org/uniprotkb/O75955/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/FLOT1","classification":"Not Classified","n_dependent_lines":71,"n_total_lines":1208,"dependency_fraction":0.058774834437086095},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CALD1","stoichiometry":0.2},{"gene":"RAB11A","stoichiometry":0.2},{"gene":"RANBP1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/FLOT1","total_profiled":1310},"omim":[{"mim_id":"616694","title":"ECM29 PROTEASOME ADAPTOR AND SCAFFOLD PROTEIN; ECPAS","url":"https://www.omim.org/entry/616694"},{"mim_id":"610195","title":"PTOV1 EXTENDED AT-HOOK-CONTAINING ADAPTOR PROTEIN; PTOV1","url":"https://www.omim.org/entry/610195"},{"mim_id":"608010","title":"NPC1-LIKE INTRACELLULAR CHOLESTEROL TRANSPORTER 1; NPC1L1","url":"https://www.omim.org/entry/608010"},{"mim_id":"606998","title":"FLOTILLIN 1; FLOT1","url":"https://www.omim.org/entry/606998"},{"mim_id":"602744","title":"GLYCERONEPHOSPHATE O-ACYLTRANSFERASE; GNPAT","url":"https://www.omim.org/entry/602744"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Golgi apparatus","reliability":"Uncertain"},{"location":"Vesicles","reliability":"Additional"},{"location":"Plasma membrane","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/FLOT1"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"O75955","domains":[{"cath_id":"-","chopping":"2-44","consensus_level":"medium","plddt":89.0653,"start":2,"end":44},{"cath_id":"3.30.479.30","chopping":"49-159","consensus_level":"high","plddt":92.5041,"start":49,"end":159}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O75955","model_url":"https://alphafold.ebi.ac.uk/files/AF-O75955-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O75955-F1-predicted_aligned_error_v6.png","plddt_mean":81.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=FLOT1","jax_strain_url":"https://www.jax.org/strain/search?query=FLOT1"},"sequence":{"accession":"O75955","fasta_url":"https://rest.uniprot.org/uniprotkb/O75955.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O75955/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O75955"}},"corpus_meta":[{"pmid":"21447726","id":"PMC_21447726","title":"Knockdown of FLOT1 impairs cell proliferation and tumorigenicity in breast cancer through upregulation of FOXO3a.","date":"2011","source":"Clinical cancer research : an official journal of the American Association for Cancer Research","url":"https://pubmed.ncbi.nlm.nih.gov/21447726","citation_count":106,"is_preprint":false},{"pmid":"26002553","id":"PMC_26002553","title":"miRNA-target network reveals miR-124as a key miRNA contributing to clear cell renal cell carcinoma aggressive behaviour by targeting CAV1 and FLOT1.","date":"2015","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/26002553","citation_count":72,"is_preprint":false},{"pmid":"25793370","id":"PMC_25793370","title":"MiR-506 is down-regulated in clear cell renal cell carcinoma and inhibits cell growth and metastasis via targeting FLOT1.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25793370","citation_count":57,"is_preprint":false},{"pmid":"30771789","id":"PMC_30771789","title":"Integration of GWAS and brain eQTL identifies FLOT1 as a risk gene for major depressive disorder.","date":"2019","source":"Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/30771789","citation_count":34,"is_preprint":false},{"pmid":"37441590","id":"PMC_37441590","title":"SDC1-TGM2-FLOT1-BHMT complex determines radiosensitivity of glioblastoma by influencing the fusion of autophagosomes with lysosomes.","date":"2023","source":"Theranostics","url":"https://pubmed.ncbi.nlm.nih.gov/37441590","citation_count":32,"is_preprint":false},{"pmid":"31933720","id":"PMC_31933720","title":"HOTAIR/miR-214-3p/FLOT1 axis plays an essential role in the proliferation, migration, and invasion of hepatocellular carcinoma.","date":"2019","source":"International journal of clinical and experimental pathology","url":"https://pubmed.ncbi.nlm.nih.gov/31933720","citation_count":30,"is_preprint":false},{"pmid":"32606796","id":"PMC_32606796","title":"Long Non-Coding RNA TUG1 Promotes Cell Proliferation and Inhibits Cell Apoptosis, Autophagy in Clear Cell Renal Cell Carcinoma via MiR-31-5p/FLOT1 Axis.","date":"2020","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/32606796","citation_count":24,"is_preprint":false},{"pmid":"37772385","id":"PMC_37772385","title":"The roles of FLOT1 in human diseases (Review).","date":"2023","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/37772385","citation_count":23,"is_preprint":false},{"pmid":"29162604","id":"PMC_29162604","title":"Suppression of Hepatic FLOT1 (Flotillin-1) by Type 2 Diabetes Mellitus Impairs the Disposal of Remnant Lipoproteins via Syndecan-1.","date":"2017","source":"Arteriosclerosis, thrombosis, and vascular biology","url":"https://pubmed.ncbi.nlm.nih.gov/29162604","citation_count":23,"is_preprint":false},{"pmid":"30838797","id":"PMC_30838797","title":"FLOT1 promotes tumor development, induces epithelial-mesenchymal transition, and modulates the cell cycle by regulating the Erk/Akt signaling pathway in lung adenocarcinoma.","date":"2019","source":"Thoracic cancer","url":"https://pubmed.ncbi.nlm.nih.gov/30838797","citation_count":22,"is_preprint":false},{"pmid":"37928269","id":"PMC_37928269","title":"FLOT1 promotes gastric cancer progression and metastasis through BCAR1/ERK signaling.","date":"2023","source":"International journal of biological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37928269","citation_count":15,"is_preprint":false},{"pmid":"32329296","id":"PMC_32329296","title":"MiR-1294 acts as a tumor inhibitor in cervical cancer by regulating FLOT1 expression.","date":"2020","source":"Journal of biological regulators and homeostatic agents","url":"https://pubmed.ncbi.nlm.nih.gov/32329296","citation_count":14,"is_preprint":false},{"pmid":"37011005","id":"PMC_37011005","title":"EIF4A3 Acts on the PI3K-AKT-ERK1/2-P70S6K Pathway through FLOT1 to Influence the Development of Lung Adenocarcinoma.","date":"2023","source":"Molecular cancer research : MCR","url":"https://pubmed.ncbi.nlm.nih.gov/37011005","citation_count":12,"is_preprint":false},{"pmid":"34115333","id":"PMC_34115333","title":"Long non-coding RNA A1BG-AS1 promotes tumorigenesis in breast cancer by sponging microRNA-485-5p and consequently increasing expression of FLOT1 expression.","date":"2021","source":"Human cell","url":"https://pubmed.ncbi.nlm.nih.gov/34115333","citation_count":12,"is_preprint":false},{"pmid":"36697954","id":"PMC_36697954","title":"FLOT1 knockdown inhibits growth of AML cells through triggering apoptosis and pyroptosis.","date":"2023","source":"Annals of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/36697954","citation_count":8,"is_preprint":false},{"pmid":"40108025","id":"PMC_40108025","title":"SMARCC1 promotes M2 macrophage polarization and reduces ferroptosis in lung cancer by activating FLOT1 transcription.","date":"2025","source":"Journal of molecular medicine (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/40108025","citation_count":5,"is_preprint":false},{"pmid":"40066501","id":"PMC_40066501","title":"FLOT1 Is a Novel Serum Biomarker of Ovarian Cancer Targeted by N6-methyladenosine Modification Inhibition.","date":"2025","source":"Cell biology international","url":"https://pubmed.ncbi.nlm.nih.gov/40066501","citation_count":4,"is_preprint":false},{"pmid":"38686057","id":"PMC_38686057","title":"Circ_0003855 involvement of esophageal cancer progression through miR-622/FLOT1.","date":"2024","source":"Oncology 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function","url":"https://pubmed.ncbi.nlm.nih.gov/41500583","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":13523,"output_tokens":3032,"usd":0.043025,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10458,"output_tokens":3362,"usd":0.06817,"stage2_stop_reason":"end_turn"},"total_usd":0.111195,"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\": 2011,\n      \"finding\": \"Knockdown of FLOT1 in breast cancer cells suppressed Akt activity, enhanced transcriptional activity of FOXO3a, upregulated CDK inhibitors p21(Cip1) and p27(Kip1), and downregulated cyclin D1, establishing FLOT1 as a promoter of proliferation via the Akt-FOXO3a-cell cycle axis.\",\n      \"method\": \"siRNA knockdown, Western blotting, luciferase reporter assay, in vitro and in vivo proliferation/tumorigenicity assays\",\n      \"journal\": \"Clinical Cancer Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KD with defined cellular phenotype and two orthogonal mechanistic readouts (Western blot + luciferase reporter), single lab\",\n      \"pmids\": [\"21447726\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"FLOT1 co-immunoprecipitates with syndecan-1 (but not caveolin-1) in liver cells; C-TRL binding to syndecan-1 enhances this association; the two molecules traffic together into lysosomes. The interaction requires the transmembrane/cytoplasmic region of syndecan-1 and the N-terminal hydrophobic domain of FLOT1. FLOT1 knockdown substantially inhibited syndecan-1 endocytosis. Adenoviral re-expression of wild-type FLOT1 (but not a mutant lacking the N-terminal hydrophobic domain) normalized plasma triglycerides in T2DM mice, demonstrating that FLOT1 mediates syndecan-1-dependent disposal of remnant lipoproteins.\",\n      \"method\": \"Co-immunoprecipitation, domain-deletion mutagenesis, siRNA knockdown in cultured liver cells, adenoviral overexpression in T2DM mice, plasma triglyceride/retinyl ester assays\",\n      \"journal\": \"Arteriosclerosis, Thrombosis, and Vascular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — reciprocal Co-IP, domain mutagenesis with functional rescue in vivo, multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"29162604\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"FLOT1 overexpression or knockdown in lung adenocarcinoma cells respectively activates or suppresses the Erk/Akt signaling pathway, promoting epithelial-mesenchymal transition and cell cycle progression, establishing FLOT1 as an upstream regulator of Erk/Akt in LUAD.\",\n      \"method\": \"Lentiviral knockdown and overexpression, Western blotting for EMT and cell cycle markers, Erk/Akt pathway analysis\",\n      \"journal\": \"Thoracic Cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD and OE models with defined pathway readout, single lab, two orthogonal approaches (KD + OE)\",\n      \"pmids\": [\"30838797\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FLOT1 interacts with BCAR1 (breast cancer anti-estrogen resistance 1), regulates BCAR1 phosphorylation and translocation, and promotes gastric cancer cell proliferation, migration, and invasion via ERK signaling. Re-expression of wild-type but not Y410F-mutant BCAR1 partially restored migration/invasion after FLOT1 knockdown, and an ERK inhibitor blocked this rescue.\",\n      \"method\": \"Co-immunoprecipitation, BCAR1 knockdown epistasis, site-directed mutagenesis (Y410F), ERK inhibitor treatment, cell migration/invasion assays\",\n      \"journal\": \"International Journal of Biological Sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, mutagenesis, and epistasis in single lab; multiple orthogonal methods\",\n      \"pmids\": [\"37928269\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"After irradiation, SDC1 carries TGM2 from the cell membrane into the cytoplasm and transports it to lysosomes by binding to FLOT1; TGM2 then recognizes BHMT on autophagosomes to coordinate autophagosome-lysosome fusion. This SDC1-TGM2-FLOT1-BHMT complex maintains autophagic flux and enhances radioresistance of glioblastoma.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, mRFP-GFP-LC3 autophagy flux assay, transmission electron microscopy, colony formation, flow cytometry\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP demonstrating complex formation, autophagy flux assay, TEM, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"37441590\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"EIF4A3 physically interacts with FLOT1 in lung adenocarcinoma cells (identified by mass spectrometry), positively regulates FLOT1 protein expression, and FLOT1 knockdown reverses EIF4A3-overexpression-induced activation of the PI3K-AKT-ERK1/2-P70S6K pathway and autophagy, placing FLOT1 downstream of EIF4A3 in this signaling cascade.\",\n      \"method\": \"Mass spectrometry co-immunoprecipitation, siRNA knockdown epistasis, Western blotting for pathway components, transcriptome sequencing\",\n      \"journal\": \"Molecular Cancer Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MS-based interaction identification plus epistasis rescue, single lab\",\n      \"pmids\": [\"37011005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FLOT1 knockdown in AML cells triggers both apoptosis and pyroptosis, while FLOT1 overexpression promotes cell growth and apoptosis resistance, establishing FLOT1 as a regulator of cell death pathways in AML.\",\n      \"method\": \"siRNA knockdown, overexpression, flow cytometry for apoptosis/pyroptosis, in vivo xenograft engraftment assay\",\n      \"journal\": \"Annals of Hematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD and OE with defined cell-death phenotypes, in vivo validation, single lab\",\n      \"pmids\": [\"36697954\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SMARCC1 activates FLOT1 transcription by binding to the FLOT1 promoter (identified by ChIP), and FLOT1 downstream promotes M2 macrophage polarization and reduces ferroptosis (maintaining GSH:GSSG ratio, reducing lipid peroxidation) in lung cancer; FLOT1 overexpression rescues the inhibitory effects of SMARCC1 knockdown on macrophage polarization and ferroptosis resistance.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP), siRNA knockdown, overexpression rescue, GSH:GSSG ratio measurement, lipid peroxidation assay, transmission electron microscopy, xenograft models, co-culture assays\",\n      \"journal\": \"Journal of Molecular Medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP establishes direct transcriptional activation, functional rescue with multiple orthogonal readouts, single lab\",\n      \"pmids\": [\"40108025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"m6A modification of FLOT1 mRNA is significantly elevated in ovarian cancer cells compared to normal ovarian epithelial cells, leading to increased FLOT1 mRNA expression; treatment with the methylation inhibitor 3-deazaadenosine decreases FLOT1 mRNA expression and suppresses tumor formation in xenograft mice.\",\n      \"method\": \"m6A modification analysis, qRT-PCR, methylation inhibitor treatment, xenograft tumor model\",\n      \"journal\": \"Cell Biology International\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, m6A measurement without identification of specific writer/eraser, pharmacological inhibition not targeting specific machinery\",\n      \"pmids\": [\"40066501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"FLOT1 interacts with the transcription factor FOSL2 (confirmed by Co-IP), and this complex upregulates EphA2 transcription (confirmed by ChIP and dual-luciferase assay), activating the p38/MAPK signaling pathway to drive pro-inflammatory microglial polarization in Alzheimer's disease models; FLOT1 silencing in APP/PS1 mice reduced neuroinflammatory markers and improved spatial memory.\",\n      \"method\": \"Co-immunoprecipitation, chromatin immunoprecipitation, dual-luciferase reporter assay, siRNA knockdown, APP/PS1 mouse model, Morris water maze\",\n      \"journal\": \"Neuropharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ChIP, and luciferase assay with in vivo validation, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"41548752\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"FLOT1 localizes to circular dorsal ruffles (CDRs) in podocytes and is required for CDR-derived macropinosome formation; depletion of FLOT1 impairs growth-factor-stimulated mTORC1 activation, demonstrating that FLOT1 links macropinocytosis to nutrient sensing and mTORC1 activity in podocytes.\",\n      \"method\": \"Imaging/immunostaining for CDR localization, Flot1 knockout cells, macropinosome formation assay, biochemical mTORC1 activation assay, cell growth measurement\",\n      \"journal\": \"Cell Structure and Function\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO model with defined localization and functional readout (mTORC1 activation), multiple orthogonal methods, single lab\",\n      \"pmids\": [\"41500583\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"FLOT1 is a lipid raft scaffold protein that mediates clathrin-independent endocytosis (including syndecan-1-dependent remnant lipoprotein uptake via its N-terminal hydrophobic domain), participates in autophagosome-lysosome fusion as part of an SDC1-TGM2-FLOT1-BHMT complex, promotes mTORC1 activation by supporting macropinosome formation, regulates cancer cell survival and proliferation through Akt/ERK signaling (partly via interactions with BCAR1 and downstream of EIF4A3), drives pro-inflammatory microglial polarization by interacting with FOSL2 to upregulate EphA2/p38-MAPK, and is itself transcriptionally activated by SMARCC1 and post-transcriptionally regulated by m6A modification and multiple miRNAs.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"FLOT1 is a membrane-associated scaffold protein that organizes clathrin-independent endocytic and macropinocytic membrane trafficking and couples these events to growth, survival, and inflammatory signaling [#1, #10]. Through its N-terminal hydrophobic domain it binds the transmembrane/cytoplasmic region of syndecan-1 to drive syndecan-1-dependent endocytosis and lysosomal disposal of remnant lipoproteins, a function whose loss raises plasma triglycerides and is rescued by wild-type but not N-terminal-deletion FLOT1 in vivo [#1]. FLOT1 is required for circular dorsal ruffle-derived macropinosome formation and for growth-factor-stimulated mTORC1 activation, linking membrane uptake to nutrient sensing [#10], and it participates in an SDC1-TGM2-FLOT1-BHMT assembly that delivers TGM2 to lysosomes to coordinate autophagosome-lysosome fusion and sustain autophagic flux [#4]. In cancer cells FLOT1 acts as an upstream driver of Akt/ERK signaling, promoting proliferation, cell-cycle progression, and epithelial-mesenchymal transition: it suppresses FOXO3a-dependent induction of p21 and p27 while sustaining cyclin D1 [#0, #2], interacts with BCAR1 to regulate its phosphorylation and ERK-dependent migration and invasion [#3], operates downstream of EIF4A3 in a PI3K-AKT-ERK-P70S6K cascade [#5], and controls apoptosis and pyroptosis sensitivity [#6]. FLOT1 expression is induced transcriptionally by SMARCC1, downstream of which it promotes M2 macrophage polarization and ferroptosis resistance [#7], and in microglia FLOT1 complexes with the transcription factor FOSL2 to upregulate EphA2 and activate p38/MAPK-driven pro-inflammatory polarization in Alzheimer's disease models [#9].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Established that FLOT1 is not merely a structural raft marker but actively promotes proliferation, by defining the Akt-FOXO3a-cell cycle axis it controls.\",\n      \"evidence\": \"siRNA knockdown with Western blot, luciferase reporter, and in vivo tumorigenicity in breast cancer cells\",\n      \"pmids\": [\"21447726\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not show how FLOT1 mechanistically engages Akt\", \"No direct binding partner linking FLOT1 to Akt identified\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined a specific molecular mechanism for FLOT1 in endocytosis by mapping its N-terminal hydrophobic domain to the syndecan-1 cytoplasmic region and demonstrating physiological rescue of lipoprotein clearance in vivo.\",\n      \"evidence\": \"Reciprocal Co-IP, domain-deletion mutagenesis, knockdown in liver cells, and adenoviral rescue with triglyceride assays in T2DM mice\",\n      \"pmids\": [\"29162604\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not resolve whether caveolin-independent uptake is general or syndecan-1-specific\", \"Structural basis of the hydrophobic-domain interaction not determined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Generalized FLOT1's role as an upstream activator of Erk/Akt beyond breast cancer, linking it to EMT and cell-cycle progression in lung adenocarcinoma.\",\n      \"evidence\": \"Lentiviral knockdown and overexpression with Western blotting of EMT/cell-cycle and pathway markers\",\n      \"pmids\": [\"30838797\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting FLOT1 to Erk/Akt activation not defined\", \"No direct molecular intermediary identified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified direct protein partners and upstream regulators that channel FLOT1 into ERK/PI3K signaling, moving from correlation to molecular epistasis.\",\n      \"evidence\": \"Co-IP and mass-spectrometry interaction (BCAR1; EIF4A3), site-directed mutagenesis (BCAR1 Y410F), and knockdown rescue with pathway inhibitors in gastric and lung cancer cells\",\n      \"pmids\": [\"37928269\", \"37011005\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether BCAR1 and EIF4A3 act in the same or parallel pathways is unresolved\", \"No reciprocal validation across independent labs\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended FLOT1's trafficking function to autophagy, placing it in a defined SDC1-TGM2-FLOT1-BHMT complex that couples lysosomal cargo delivery to autophagosome fusion and radioresistance.\",\n      \"evidence\": \"Co-IP, immunofluorescence, mRFP-GFP-LC3 flux assay, and TEM in glioblastoma cells\",\n      \"pmids\": [\"37441590\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding interfaces within the four-member complex not mapped\", \"Stoichiometry and assembly order beyond Co-IP unestablished\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showed FLOT1 controls cell-death decisions, regulating both apoptosis and pyroptosis in addition to proliferation.\",\n      \"evidence\": \"Knockdown/overexpression with flow cytometry and xenograft engraftment in AML cells\",\n      \"pmids\": [\"36697954\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular link between FLOT1 and pyroptotic machinery not identified\", \"Whether death regulation is downstream of its known signaling roles is unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified upstream transcriptional control of FLOT1 (SMARCC1) and post-transcriptional control (m6A), and linked FLOT1 to immune polarization and ferroptosis resistance.\",\n      \"evidence\": \"ChIP, knockdown/overexpression rescue, GSH:GSSG and lipid peroxidation assays (SMARCC1); m6A analysis with methylation inhibitor and xenografts (ovarian)\",\n      \"pmids\": [\"40108025\", \"40066501\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific m6A writer/eraser for FLOT1 mRNA not identified\", \"Mechanism by which FLOT1 suppresses ferroptosis not defined\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Defined non-cancer functions: FLOT1 drives macropinocytosis-coupled mTORC1 activation in podocytes and complexes with FOSL2 to drive neuroinflammatory microglial polarization in Alzheimer's models.\",\n      \"evidence\": \"Flot1 knockout cells with macropinosome and mTORC1 assays (podocytes); Co-IP, ChIP, luciferase, and APP/PS1 mouse behavior (microglia)\",\n      \"pmids\": [\"41500583\", \"41548752\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How macropinosome-localized FLOT1 transmits the signal to mTORC1 is not resolved\", \"Whether the FOSL2 interaction is direct or scaffolded is not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether FLOT1's diverse signaling roles (Akt/ERK, mTORC1, autophagy, inflammation) all derive from a single core function in raft-based membrane trafficking, or represent independent scaffold activities, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of FLOT1 in any of its complexes\", \"No unifying biochemical mechanism connecting its endocytic and transcription-associated roles\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 3, 4, 9]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 10]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [1, 4]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [1, 10]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 3, 5]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"complexes\": [\n      \"SDC1-TGM2-FLOT1-BHMT complex\",\n      \"FLOT1-FOSL2 complex\"\n    ],\n    \"partners\": [\n      \"SDC1\",\n      \"BCAR1\",\n      \"TGM2\",\n      \"EIF4A3\",\n      \"FOSL2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}