{"gene":"SEPTIN6","run_date":"2026-06-10T07:46:30","timeline":{"discoveries":[{"year":2007,"finding":"SEPTIN6 was identified as a binding partner of HCV NS5b RNA-dependent RNA polymerase by yeast two-hybrid screening, and SEPTIN6 also interacts with hnRNP A1. Knockdown of SEPTIN6 or overexpression of N-terminally truncated SEPTIN6 inhibited HCV replication, establishing a functional role for SEPTIN6 in HCV RNA replication through protein-protein interactions.","method":"Yeast two-hybrid screening, coimmunoprecipitation, siRNA knockdown, dominant-negative overexpression","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal binding confirmed by two methods (Y2H + Co-IP), functional knockdown and dominant-negative results, single lab","pmids":["17229681"],"is_preprint":false},{"year":2002,"finding":"SEPTIN6 is fused to MLL in infant acute myeloid leukemia via t(X;11)(q24;q23) and related complex rearrangements, generating an MLL-SEPTIN6 fusion protein containing almost the entire SEPTIN6 sequence. SEPTIN6 encodes at least two protein isoforms by alternative splicing. The fusion protein structure parallels other MLL-septin fusions (MLL-CDCREL1, MLL-MSF), suggesting a common leukemogenic pathway.","method":"RT-PCR, sequencing, Southern blot, cytogenetics, FISH","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Strong — molecular characterization replicated across multiple cases and independent labs, fusion transcript and protein structure established","pmids":["11809673","12096348","11477664","18492691"],"is_preprint":false},{"year":2002,"finding":"The MLL genomic breakpoint in the MLL-SEPTIN6 rearrangement was identified as a functional DNA topoisomerase II cleavage site in an in vitro cleavage assay, implicating topoisomerase II activity in generating the chromosomal translocation.","method":"In vitro topoisomerase II cleavage assay, panhandle PCR, Southern blot","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic assay, single lab, replicated in second case","pmids":["12096348"],"is_preprint":false},{"year":2005,"finding":"Sept6-deficient mice showed no gross abnormalities, no cytokinesis defects, and no spontaneous malignancy. Loss of Sept6 did not alter levels of other septins, did not worsen the Sept4-null phenotype, and did not affect the myeloproliferative disease induced by MLL-SEPT6, indicating that SEPT6 does not function as a tumor suppressor and that there is high redundancy within the septin system.","method":"Gene knockout (Sept6-deficient mice), bone marrow transplantation, retroviral MLL-SEPT6 expression, in vitro siRNA of Sept11","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO mouse model with multiple phenotypic readouts, epistasis with Sept4-null and MLL-SEPT6 disease model, independent genetic manipulations","pmids":["16314519"],"is_preprint":false},{"year":2011,"finding":"SEPT6 localizes to branch points of developing dendrites and to bases of filopodia and spines in hippocampal neurons, forming ring-like structures (~0.5 μm diameter). SEPT6 is expressed beginning at stage 4 (dendritic outgrowth) and is not a post-synaptic density (PSD) protein. RNAi knockdown of SEPT6 at early developmental stage significantly reduced dendritic length and branch number, demonstrating a role in dendritic cytoarchitecture.","method":"Immunocytochemistry, detergent extraction fractionation, RNAi knockdown with morphological quantification in dissociated hippocampal cultures","journal":"Molecules and cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — localization tied to functional consequence via RNAi, multiple orthogonal methods, single lab","pmids":["21544625"],"is_preprint":false},{"year":2014,"finding":"SEPT6 and SEPT7 complexes bound to F-actin regulate protein sorting during multivesicular body (MVB) biogenesis. These complexes bind the AP-3 adaptor complex, modulate AP-3 membrane interactions and motility of AP-3-positive endosomes. SEPT6/SEPT7 interactions also influence membrane association of ESCRT-I, coordinating two cargo-sorting machineries during MVB biogenesis. This coordination requires the E3 ubiquitin ligase LRSAM1.","method":"Co-immunoprecipitation, siRNA knockdown, live-cell imaging of endosome motility, subcellular fractionation","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, functional knockdown with defined endosomal phenotype, single lab with multiple orthogonal methods","pmids":["25380047"],"is_preprint":false},{"year":2007,"finding":"SEPT12 interacts with SEPT6 both in vitro and in vivo (in HeLa cells), independently of the SEPT6 coiled-coil domain. Co-expression of SEPT12 altered the filamentous structure of SEPT6 in HeLa cells, demonstrating that septin-septin interactions modulate SEPT6 filament organization.","method":"Co-immunoprecipitation, in vitro binding assay, co-expression with fluorescence microscopy in HeLa cells, deletion mutant analysis","journal":"Journal of biochemistry and molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro and in vivo binding confirmed, domain mapping, single lab","pmids":["18047794"],"is_preprint":false},{"year":2021,"finding":"LSD1 demethylates the SEPT6 promoter to positively regulate SEPT6 expression at the transcriptional level. LSD1-mediated upregulation of SEPT6 activates the TGF-β1/Smad signaling pathway to promote NSCLC cell proliferation, migration, invasion, and in vivo metastasis.","method":"Lentivirus-mediated LSD1 silencing and SEPT6 overexpression, RT-qPCR, western blotting, EdU proliferation assay, Transwell assay, flow cytometry, xenograft mouse model","journal":"Cancer gene therapy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epistatic rescue experiment (LSD1 KD + SEPT6 OE), multiple functional assays, in vivo validation, single lab","pmids":["33664458"],"is_preprint":false},{"year":2021,"finding":"SEPT6 promotes HCC cell proliferation, migration, and invasion by facilitating F-actin formation, which leads to LATS1 dephosphorylation, Hippo pathway inhibition, and YAP nuclear translocation with downstream upregulation of cyclin D1 and MMP2. YAP overexpression rescued SEPT6-knockdown phenotypes and YAP knockdown blocked SEPT6-overexpression effects, placing SEPT6 upstream of YAP in HCC.","method":"Stable knockdown/overexpression cell lines, CCK-8, flow cytometry, Transwell assay, YAP rescue and knockdown epistasis, western blotting","journal":"International journal of oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis (YAP rescue), multiple functional readouts, single lab","pmids":["33846777"],"is_preprint":false},{"year":2018,"finding":"SEPT6 overexpression in hepatic stellate cells (HSCs) promotes TGF-β1 expression and phosphorylation of Smad2, Smad3, ERK, JNK, SAPK-2, and AKT, driving fibrogenic activation. Blockade of TGF-β1/Smad signaling reversed SEPT6 overexpression effects on α-SMA, cyclin D1, BCL2, and MMP-2/-9. In vivo, adenovirus-mediated SEPT6 inhibition attenuated TAA-induced liver fibrosis in rats.","method":"Overexpression/knockdown in HSC lines, pharmacological TGF-β1/Smad blockade (SB431542), in vivo adenovirus-mediated knockdown in rat fibrosis model, western blotting","journal":"Laboratory investigation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pathway blockade epistasis, in vivo validation, multiple signaling readouts, single lab","pmids":["30315255"],"is_preprint":false},{"year":2017,"finding":"SEPT6-deficient hematopoietic stem cells (HSCs) exhibit increased engraftment potential but impaired lymphoid differentiation, with reduced T-cell and increased B-cell contribution. Multipotent progenitor cells showed distinct SEPT6 filament organization but were functionally unimpaired by SEPT6 deficiency, indicating SEPT6 specifically regulates long-term HSC function and lymphoid lineage choice.","method":"Sept6-deficient mouse model, bone marrow transplantation, flow cytometry of hematopoietic lineages, fluorescence microscopy of septin filaments","journal":"Experimental hematology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO mouse with defined hematopoietic phenotype, multiple lineage readouts, single lab","pmids":["28751190"],"is_preprint":false},{"year":2021,"finding":"A germline stop-loss mutation in SEPT6 caused X-linked congenital neutropenia with myeloid tetraploidy in a male infant. Reduced SEPT6 staining was found in bone marrow granulocyte precursors and megakaryocytes. SEPT6 KO in an erythroid cell line produced multinucleation. In silico modeling predicted the mutation disrupts SEPT6 coiled-coil dimerization, impairing filament formation. These data establish a critical role for SEPT6 in chromosomal segregation in myeloid progenitors.","method":"Next-generation sequencing, CRISPR/Cas9 knock-in and knockout, iPSC myeloid colony assay, immunohistochemistry, in silico structural modeling","journal":"American journal of hematology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR KO functional validation, patient-derived iPSC assay, multiple cell-type readouts; in silico structural modeling lowers confidence for the dimerization mechanism","pmids":["34677878"],"is_preprint":false},{"year":2023,"finding":"Zebrafish Sept6-null mutants are viable without gross developmental defects but are more susceptible to Shigella infection, demonstrating a role for Sept6 in host defence against intracellular bacterial pathogens in vivo.","method":"CRISPR/Cas9 null mutant generation, in vivo Shigella infection model in zebrafish larvae, survival analysis, RT-qPCR of other septin genes","journal":"Cytoskeleton (Hoboken, N.J.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean null mutant with defined infection phenotype, ortholog validation consistent with mammalian SEPT6 function, single lab","pmids":["36855298"],"is_preprint":false},{"year":2018,"finding":"In stored platelets, miR-223 directly targets the 3'UTR of SEPT6 mRNA and downregulates SEPT6 expression. SEPT6 mRNA co-immunoprecipitates with AGO2 in platelet extracts, and a luciferase reporter with SEPT6 3'UTR is downregulated by miR-223, establishing miR-223 as a post-transcriptional regulator of SEPT6 in platelets.","method":"AGO2 co-immunoprecipitation, luciferase reporter assay with SEPT6 3'UTR, anti-miR-223 rescue in platelets","journal":"MicroRNA (Shariqah, United Arab Emirates)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — AGO2 pull-down plus reporter assay confirms direct miRNA-mRNA interaction, single lab, two orthogonal methods","pmids":["29943706"],"is_preprint":false},{"year":2025,"finding":"SEPT6 undergoes liquid-liquid phase separation (LLPS) both in vitro and in vivo in polarized epithelial (MDCK) cells, mediated by weak, multivalent interactions through its C-terminal tail. SEPT6 mutants defective in LLPS in vitro also fail to support adherens junction integrity and cell polarity establishment in 2D and 3D cultures, demonstrating that LLPS-competent SEPT6 is required for epithelial polarity.","method":"In vitro LLPS assay, live-cell imaging of septin dynamics in MDCK cells, SEPT6 C-terminal tail mutant analysis, 3D lumen formation assay","journal":"Journal of molecular cell biology","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — in vitro reconstitution of LLPS plus cell-based mutant rescue, multiple orthogonal methods, single lab","pmids":["39973116"],"is_preprint":false},{"year":2021,"finding":"SEPT6 acts upstream of UBC (ubiquitin C) in prostate cancer cells: SEPT6 overexpression decreased UBC expression while SEPT6 knockdown increased it, and SEPT6 co-localizes with UBC in prostate cancer cells by immunofluorescence. SEPT6 inhibited tumor growth in vivo through this UBC-mediated reduction of overall ubiquitination levels.","method":"Overexpression/knockdown, immunofluorescence co-localization, CCK-8, flow cytometry, xenograft tumor formation","journal":"Mediators of inflammation","confidence":"Low","confidence_rationale":"Tier 3 / Weak — co-localization only (no direct binding assay), epistasis based on expression levels, single lab, no biochemical interaction confirmation","pmids":["34966246"],"is_preprint":false},{"year":2019,"finding":"SEPT6 overexpression in dairy cow mammary epithelial cells upregulates mTOR, p-mTOR, S6K1, and p-S6K1, promoting cell growth and casein (CSN2) synthesis. mTOR inhibition blocked the effects of SEPT6 overexpression, placing SEPT6 upstream of the mTORC1 pathway in amino acid-mediated casein synthesis.","method":"Overexpression/inhibition of SEPT6, mTOR inhibition rescue, western blotting, cell growth assays in primary dairy cow mammary epithelial cells","journal":"The Journal of dairy research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single cell type (non-human), epistasis based on pharmacological inhibition only, no direct binding shown","pmids":["31122298"],"is_preprint":false}],"current_model":"SEPTIN6 is a GTP-binding cytoskeletal protein that functions as a scaffold within heteropolymeric septin complexes (e.g., SEPT2/6/7), undergoes liquid-liquid phase separation via its C-terminal tail to support epithelial polarity and adherens junction integrity, localizes to dendritic branch points and spine bases to regulate neuronal cytoarchitecture, participates in AP-3/ESCRT-dependent MVB biogenesis by binding F-actin-associated SEPT7 complexes, facilitates HCV replication through interaction with NS5b and hnRNP A1, is regulated post-transcriptionally by miR-223/AGO2 and transcriptionally by LSD1-mediated promoter demethylation, plays a non-redundant role in chromosomal segregation in myeloid progenitors and lymphoid differentiation of hematopoietic stem cells, and is recurrently fused to MLL (KMT2A) in infant AML via translocations at a topoisomerase II cleavage site, generating a leukemogenic fusion protein."},"narrative":{"mechanistic_narrative":"SEPTIN6 is a GTP-binding cytoskeletal protein that assembles into heteromeric septin filaments and serves as a membrane- and actin-associated scaffold supporting cytoarchitecture across diverse cell types [PMID:18047794, PMID:21544625]. Within neurons, SEPT6 localizes to dendritic branch points and the bases of filopodia and spines as ring-like structures and is required for dendritic outgrowth and branching [PMID:21544625]. It engages partner septins through interactions distinct from its coiled-coil domain, and these septin-septin contacts remodel SEPT6 filament organization [PMID:18047794]. SEPT6 self-organization extends to liquid-liquid phase separation driven by weak multivalent interactions of its C-terminal tail, a property required to maintain adherens junction integrity and epithelial polarity [PMID:39973116]. In membrane trafficking, F-actin-bound SEPT6/SEPT7 complexes bind the AP-3 adaptor and influence ESCRT-I membrane association, coordinating cargo sorting during multivesicular body biogenesis in an LRSAM1-dependent manner [PMID:25380047]. SEPT6 has a non-redundant role in hematopoiesis, regulating long-term HSC function and lymphoid lineage choice [PMID:28751190], and in chromosomal segregation of myeloid progenitors, where a germline stop-loss mutation causes X-linked congenital neutropenia with myeloid tetraploidy [PMID:34677878]. SEPT6 also contributes to host defense against intracellular bacteria [PMID:36855298] and is exploited by hepatitis C virus, binding the NS5b RNA-dependent RNA polymerase and hnRNP A1 to support viral RNA replication [PMID:17229681]. Across epithelial cancers and fibrosis, SEPT6 acts upstream of pro-proliferative signaling, promoting F-actin formation to inhibit the Hippo pathway and drive YAP nuclear translocation [PMID:33846777] and activating TGF-β1/Smad signaling [PMID:30315255]. SEPT6 expression is controlled post-transcriptionally by miR-223/AGO2 [PMID:29943706] and transcriptionally by LSD1-mediated promoter demethylation [PMID:33664458]. SEPTIN6 is recurrently fused to MLL (KMT2A) in infant acute myeloid leukemia via t(X;11)(q24;q23) at a topoisomerase II cleavage site, generating an MLL-SEPT6 leukemogenic fusion protein [PMID:11809673, PMID:12096348, PMID:11477664, PMID:18492691].","teleology":[{"year":2002,"claim":"Establishing how SEPTIN6 contributes to leukemia, this work showed it is recurrently fused to MLL in infant AML, producing a fusion protein incorporating nearly the entire septin sequence.","evidence":"RT-PCR, sequencing, cytogenetics and FISH across multiple infant AML cases","pmids":["11809673","12096348","11477664","18492691"],"confidence":"Medium","gaps":["Does not define the biochemical activity of the MLL-SEPT6 fusion protein","Mechanism of leukemogenic transformation not resolved"]},{"year":2002,"claim":"Addressing why this specific translocation arises, the MLL breakpoint was shown to be a functional topoisomerase II cleavage site, implicating enzymatic DNA cleavage in generating the rearrangement.","evidence":"In vitro topoisomerase II cleavage assay with panhandle PCR and Southern blot","pmids":["12096348"],"confidence":"Medium","gaps":["In vitro assay does not prove topoisomerase II generates the break in vivo","Single-lab characterization"]},{"year":2005,"claim":"Testing whether SEPT6 acts as a tumor suppressor or essential cytokinesis factor, knockout mice revealed extensive septin redundancy and no requirement for SEPT6 in normal development or MLL-SEPT6-driven disease.","evidence":"Sept6-deficient mice with bone marrow transplantation, retroviral MLL-SEPT6 expression, and Sept4-null epistasis","pmids":["16314519"],"confidence":"High","gaps":["Redundancy obscures any SEPT6-specific function under unstressed conditions","Does not address tissue-specific or context-dependent roles"]},{"year":2007,"claim":"Connecting SEPT6 to viral pathogenesis, it was identified as an NS5b and hnRNP A1 interactor required for efficient HCV RNA replication.","evidence":"Yeast two-hybrid, co-immunoprecipitation, siRNA knockdown and dominant-negative overexpression","pmids":["17229681"],"confidence":"Medium","gaps":["Molecular role of SEPT6 in the replication complex undefined","Single-lab finding"]},{"year":2007,"claim":"To understand how SEPT6 filaments are organized, SEPT12 was shown to bind SEPT6 independently of its coiled-coil and to remodel its filamentous structure, demonstrating septin-septin regulation of assembly.","evidence":"In vitro binding, co-IP, co-expression microscopy and deletion mapping in HeLa cells","pmids":["18047794"],"confidence":"Medium","gaps":["Functional consequence of SEPT6-SEPT12 filaments not established","Stoichiometry within native septin complexes unknown"]},{"year":2011,"claim":"Defining a neuronal function, SEPT6 was localized to dendritic branch points and spine/filopodia bases and shown to be required for dendritic outgrowth and branching.","evidence":"Immunocytochemistry, fractionation and RNAi with morphological quantification in hippocampal neurons","pmids":["21544625"],"confidence":"Medium","gaps":["Molecular mechanism linking septin rings to dendrite morphology unclear","Partners at branch points not identified"]},{"year":2014,"claim":"Linking SEPT6 to membrane trafficking, F-actin-bound SEPT6/SEPT7 complexes were shown to coordinate AP-3 and ESCRT-I machineries during MVB biogenesis.","evidence":"Reciprocal co-IP, siRNA knockdown, live-cell endosome imaging and fractionation","pmids":["25380047"],"confidence":"Medium","gaps":["How septins physically bridge AP-3 and ESCRT-I is unresolved","Role of LRSAM1 mechanistically undefined"]},{"year":2017,"claim":"Resolving a non-redundant hematopoietic role, SEPT6-deficient HSCs showed increased engraftment but impaired lymphoid differentiation, establishing SEPT6 control of long-term HSC function and lineage choice.","evidence":"Sept6-deficient mouse model with bone marrow transplantation and flow cytometry of lineages","pmids":["28751190"],"confidence":"Medium","gaps":["Molecular basis of biased lineage output unknown","Reconciliation with earlier redundancy data not addressed"]},{"year":2018,"claim":"Establishing post-transcriptional control, miR-223 was shown to directly target the SEPT6 3'UTR via AGO2 to downregulate SEPT6 in platelets.","evidence":"AGO2 co-IP, luciferase 3'UTR reporter and anti-miR-223 rescue in stored platelets","pmids":["29943706"],"confidence":"Medium","gaps":["Functional consequence of SEPT6 loss in platelets not defined","Whether this regulation operates outside platelets unknown"]},{"year":2018,"claim":"Implicating SEPT6 in fibrosis signaling, its overexpression in hepatic stellate cells was shown to drive TGF-β1/Smad-dependent fibrogenic activation in vitro and in vivo.","evidence":"Overexpression/knockdown, pharmacological TGF-β1/Smad blockade and adenoviral knockdown in a rat fibrosis model","pmids":["30315255"],"confidence":"Medium","gaps":["Direct molecular link between SEPT6 and TGF-β1 induction not defined","Single-lab finding"]},{"year":2021,"claim":"Connecting transcriptional regulation to cancer, LSD1 was shown to demethylate the SEPT6 promoter to upregulate SEPT6 and activate TGF-β1/Smad signaling, promoting NSCLC progression.","evidence":"Lentiviral LSD1 silencing and SEPT6 overexpression with functional assays and xenografts","pmids":["33664458"],"confidence":"Medium","gaps":["Direct binding of LSD1 to the SEPT6 promoter not demonstrated mechanistically","Single-lab finding"]},{"year":2021,"claim":"Placing SEPT6 in oncogenic signaling, it was shown to promote F-actin formation that inhibits the Hippo pathway and drives YAP nuclear translocation in HCC.","evidence":"Stable knockdown/overexpression with YAP rescue and knockdown epistasis and functional assays","pmids":["33846777"],"confidence":"Medium","gaps":["How SEPT6/F-actin regulates LATS1 phosphorylation is undefined","Single-lab finding"]},{"year":2021,"claim":"Defining a Mendelian disease link, a germline stop-loss mutation was shown to cause X-linked congenital neutropenia with myeloid tetraploidy, establishing SEPT6 in chromosomal segregation of myeloid progenitors.","evidence":"NGS, CRISPR knock-in/knockout, patient iPSC myeloid colony assays and in silico structural modeling","pmids":["34677878"],"confidence":"Medium","gaps":["Dimerization-disruption mechanism rests on in silico modeling","Single patient case"]},{"year":2021,"claim":"A proposed prostate cancer role placed SEPT6 upstream of ubiquitin C to reduce ubiquitination and inhibit tumor growth.","evidence":"Overexpression/knockdown, immunofluorescence co-localization and xenograft assays","pmids":["34966246"],"confidence":"Low","gaps":["Co-localization only; no direct SEPT6-UBC binding assay","Epistasis inferred from expression changes alone"]},{"year":2023,"claim":"Extending function to host defense, zebrafish Sept6-null mutants were viable but more susceptible to Shigella, demonstrating an in vivo role against intracellular bacteria.","evidence":"CRISPR/Cas9 null mutant zebrafish with in vivo Shigella infection and survival analysis","pmids":["36855298"],"confidence":"Medium","gaps":["Mechanism of septin-mediated bacterial restriction not defined","Conservation to mammalian SEPT6 inferred, not tested"]},{"year":2025,"claim":"Defining a biophysical mechanism, SEPT6 was shown to undergo C-terminal-tail-driven liquid-liquid phase separation that is required for adherens junction integrity and epithelial polarity.","evidence":"In vitro LLPS reconstitution and C-terminal mutant rescue in MDCK 2D/3D cultures with live imaging","pmids":["39973116"],"confidence":"Medium","gaps":["How LLPS integrates with canonical septin filament assembly unclear","Single-lab finding"]},{"year":null,"claim":"It remains unknown how SEPT6's distinct activities — filament scaffolding, LLPS, trafficking coordination, and chromosomal segregation — are partitioned across cell types, and what biochemical activity the MLL-SEPT6 fusion confers in leukemogenesis.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of native SEPT6 heteropolymers in human cells","Mechanism of MLL-SEPT6 transformation unresolved","Direct enzymatic/GTPase role of SEPT6 not functionally dissected in the corpus"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[5,8]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[4,6,14]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[5]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[4,6]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[5]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[14]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[5]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[8,9]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1,11]}],"complexes":["SEPT6/SEPT7 complex","MLL-SEPT6 fusion"],"partners":["SEPT7","SEPT12","NS5B","HNRNPA1","AGO2","KMT2A"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q14141","full_name":"Septin-6","aliases":[],"length_aa":434,"mass_kda":49.7,"function":"Filament-forming cytoskeletal GTPase. Required for normal organization of the actin cytoskeleton. Involved in cytokinesis. May play a role in HCV RNA replication. Forms a filamentous structure with SEPTIN12, SEPTIN6, SEPTIN2 and probably SEPTIN4 at the sperm annulus which is required for the structural integrity and motility of the sperm tail during postmeiotic differentiation (PubMed:25588830)","subcellular_location":"Cytoplasm; Cytoplasm, cytoskeleton, spindle; Chromosome, centromere, kinetochore; Cleavage furrow; Midbody; Cell projection, cilium, flagellum","url":"https://www.uniprot.org/uniprotkb/Q14141/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SEPTIN6","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1090,"dependency_fraction":0.0009174311926605505},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"SEPT11","stoichiometry":10.0},{"gene":"SEPT2","stoichiometry":10.0},{"gene":"SEPT9","stoichiometry":10.0},{"gene":"SEPT7","stoichiometry":10.0},{"gene":"SEPT8","stoichiometry":10.0},{"gene":"COPB2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/SEPTIN6","total_profiled":1310},"omim":[],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"},{"location":"Primary cilium","reliability":"Additional"},{"location":"Mid piece","reliability":"Additional"},{"location":"Principal piece","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":215.5}],"url":"https://www.proteinatlas.org/search/SEPTIN6"},"hgnc":{"alias_symbol":["KIAA0128","SEP2","SEPT2","MGC16619","MGC20339","Septin-6"],"prev_symbol":["SEPT6"]},"alphafold":{"accession":"Q14141","domains":[{"cath_id":"3.40.50.300","chopping":"37-305","consensus_level":"high","plddt":88.5117,"start":37,"end":305},{"cath_id":"1.20.5","chopping":"326-394","consensus_level":"medium","plddt":85.5329,"start":326,"end":394}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q14141","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q14141-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q14141-F1-predicted_aligned_error_v6.png","plddt_mean":80.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SEPTIN6","jax_strain_url":"https://www.jax.org/strain/search?query=SEPTIN6"},"sequence":{"accession":"Q14141","fasta_url":"https://rest.uniprot.org/uniprotkb/Q14141.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q14141/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q14141"}},"corpus_meta":[{"pmid":"17229681","id":"PMC_17229681","title":"An RNA-binding protein, hnRNP A1, and a scaffold protein, septin 6, facilitate hepatitis C virus replication.","date":"2007","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/17229681","citation_count":88,"is_preprint":false},{"pmid":"25519054","id":"PMC_25519054","title":"MiR-223-3p targeting SEPT6 promotes the biological behavior of prostate cancer.","date":"2014","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/25519054","citation_count":67,"is_preprint":false},{"pmid":"11809673","id":"PMC_11809673","title":"SEPTIN6, a human homologue to mouse Septin6, is fused to MLL in infant acute myeloid leukemia with complex chromosomal abnormalities involving 11q23 and Xq24.","date":"2002","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/11809673","citation_count":51,"is_preprint":false},{"pmid":"16314519","id":"PMC_16314519","title":"Disruption of Sept6, a fusion partner gene of MLL, does not affect ontogeny, leukemogenesis induced by MLL-SEPT6, or phenotype induced by the loss of Sept4.","date":"2005","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/16314519","citation_count":50,"is_preprint":false},{"pmid":"21544625","id":"PMC_21544625","title":"Septin 6 regulates the cytoarchitecture of neurons through localization at dendritic branch points and bases of protrusions.","date":"2011","source":"Molecules and cells","url":"https://pubmed.ncbi.nlm.nih.gov/21544625","citation_count":48,"is_preprint":false},{"pmid":"12096348","id":"PMC_12096348","title":"MLL-SEPTIN6 fusion recurs in novel translocation of chromosomes 3, X, and 11 in infant acute myelomonocytic leukaemia and in t(X;11) in infant acute myeloid leukaemia, and MLL genomic breakpoint in complex MLL-SEPTIN6 rearrangement is a DNA topoisomerase II cleavage site.","date":"2002","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/12096348","citation_count":47,"is_preprint":false},{"pmid":"11477664","id":"PMC_11477664","title":"An ins(X;11)(q24;q23) fuses the MLL and the Septin 6/KIAA0128 gene in an infant with AML-M2.","date":"2001","source":"Genes, chromosomes & cancer","url":"https://pubmed.ncbi.nlm.nih.gov/11477664","citation_count":42,"is_preprint":false},{"pmid":"33664458","id":"PMC_33664458","title":"LSD1-mediated stabilization of SEPT6 protein activates the TGF-β1 pathway and regulates non-small-cell lung cancer metastasis.","date":"2021","source":"Cancer gene therapy","url":"https://pubmed.ncbi.nlm.nih.gov/33664458","citation_count":22,"is_preprint":false},{"pmid":"12874781","id":"PMC_12874781","title":"MLL/SEPTIN6 chimeric transcript from inv ins(X;11)(q24;q23q13) in acute monocytic leukemia: report of a case and review of the literature.","date":"2003","source":"Genes, chromosomes & cancer","url":"https://pubmed.ncbi.nlm.nih.gov/12874781","citation_count":22,"is_preprint":false},{"pmid":"25380047","id":"PMC_25380047","title":"Septin6 and Septin7 GTP binding proteins regulate AP-3- and ESCRT-dependent multivesicular body biogenesis.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25380047","citation_count":21,"is_preprint":false},{"pmid":"18492691","id":"PMC_18492691","title":"Molecular characterization of the MLL-SEPT6 fusion gene in acute myeloid leukemia: identification of novel fusion transcripts and cloning of genomic breakpoint junctions.","date":"2008","source":"Haematologica","url":"https://pubmed.ncbi.nlm.nih.gov/18492691","citation_count":15,"is_preprint":false},{"pmid":"33846777","id":"PMC_33846777","title":"SEPT6 drives hepatocellular carcinoma cell proliferation, migration and invasion via the Hippo/YAP signaling pathway.","date":"2021","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/33846777","citation_count":14,"is_preprint":false},{"pmid":"18047794","id":"PMC_18047794","title":"SEPT12 interacts with SEPT6 and this interaction alters the filament structure of SEPT6 in Hela cells.","date":"2007","source":"Journal of biochemistry and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/18047794","citation_count":14,"is_preprint":false},{"pmid":"16843108","id":"PMC_16843108","title":"MLL-SEPT6 fusion transcript with a novel sequence in an infant with acute myeloid leukemia.","date":"2006","source":"Cancer genetics and cytogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/16843108","citation_count":12,"is_preprint":false},{"pmid":"30315255","id":"PMC_30315255","title":"Effect of SEPT6 on the biological behavior of hepatic stellate cells and liver fibrosis in rats and its mechanism.","date":"2018","source":"Laboratory investigation; a journal of technical methods and pathology","url":"https://pubmed.ncbi.nlm.nih.gov/30315255","citation_count":10,"is_preprint":false},{"pmid":"28751190","id":"PMC_28751190","title":"Septin 6 regulates engraftment and lymphoid differentiation potential of murine long-term hematopoietic stem cells.","date":"2017","source":"Experimental hematology","url":"https://pubmed.ncbi.nlm.nih.gov/28751190","citation_count":10,"is_preprint":false},{"pmid":"36855298","id":"PMC_36855298","title":"Zebrafish null mutants of Sept6 and Sept15 are viable but more susceptible to Shigella infection.","date":"2023","source":"Cytoskeleton (Hoboken, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/36855298","citation_count":9,"is_preprint":false},{"pmid":"34966246","id":"PMC_34966246","title":"UBC Mediated by SEPT6 Inhibited the Progression of Prostate Cancer.","date":"2021","source":"Mediators of inflammation","url":"https://pubmed.ncbi.nlm.nih.gov/34966246","citation_count":8,"is_preprint":false},{"pmid":"39973116","id":"PMC_39973116","title":"Multivalent interactions of Septin 6 promote the establishment of epithelial cell polarity.","date":"2025","source":"Journal of molecular cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/39973116","citation_count":6,"is_preprint":false},{"pmid":"29943706","id":"PMC_29943706","title":"MicroRNA-223 Regulates Septin-2 and Septin-6 in Stored Platelets.","date":"2018","source":"MicroRNA (Shariqah, United Arab Emirates)","url":"https://pubmed.ncbi.nlm.nih.gov/29943706","citation_count":5,"is_preprint":false},{"pmid":"34677878","id":"PMC_34677878","title":"Congenital X-linked neutropenia with myelodysplasia and somatic tetraploidy due to a germline mutation in SEPT6.","date":"2021","source":"American journal of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/34677878","citation_count":4,"is_preprint":false},{"pmid":"31122298","id":"PMC_31122298","title":"Septin6 regulates cell growth and casein synthesis in dairy cow mammary epithelial cells via mTORC1 pathway.","date":"2019","source":"The Journal of dairy research","url":"https://pubmed.ncbi.nlm.nih.gov/31122298","citation_count":4,"is_preprint":false},{"pmid":"36213638","id":"PMC_36213638","title":"Clinical profile in KMT2A-SEPT6-positive acute myeloid leukemia: Does it often co-occur with NRAS mutations?","date":"2022","source":"Frontiers in medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36213638","citation_count":1,"is_preprint":false},{"pmid":"41203180","id":"PMC_41203180","title":"Molecular and functional characterization of septin 6 in rohu (Labeo rohita) reveals a strong immunopotentiating role and involvement in broad-spectrum disease protection.","date":"2025","source":"International journal of biological macromolecules","url":"https://pubmed.ncbi.nlm.nih.gov/41203180","citation_count":1,"is_preprint":false},{"pmid":"42088107","id":"PMC_42088107","title":"X-linked SEPTIN6-related congenital neutropenia and B cell deficiency.","date":"2026","source":"Journal of human immunity","url":"https://pubmed.ncbi.nlm.nih.gov/42088107","citation_count":0,"is_preprint":false},{"pmid":"38152368","id":"PMC_38152368","title":"Co-existence of KMT2A::SEPTIN6 fusion and DIS3 variant in a pediatric case with acute myeloid leukemia: a case report and literature review.","date":"2023","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/38152368","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14490,"output_tokens":4599,"usd":0.056227,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12743,"output_tokens":5019,"usd":0.094595,"stage2_stop_reason":"end_turn"},"total_usd":0.150822,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"SEPTIN6 was identified as a binding partner of HCV NS5b RNA-dependent RNA polymerase by yeast two-hybrid screening, and SEPTIN6 also interacts with hnRNP A1. Knockdown of SEPTIN6 or overexpression of N-terminally truncated SEPTIN6 inhibited HCV replication, establishing a functional role for SEPTIN6 in HCV RNA replication through protein-protein interactions.\",\n      \"method\": \"Yeast two-hybrid screening, coimmunoprecipitation, siRNA knockdown, dominant-negative overexpression\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding confirmed by two methods (Y2H + Co-IP), functional knockdown and dominant-negative results, single lab\",\n      \"pmids\": [\"17229681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"SEPTIN6 is fused to MLL in infant acute myeloid leukemia via t(X;11)(q24;q23) and related complex rearrangements, generating an MLL-SEPTIN6 fusion protein containing almost the entire SEPTIN6 sequence. SEPTIN6 encodes at least two protein isoforms by alternative splicing. The fusion protein structure parallels other MLL-septin fusions (MLL-CDCREL1, MLL-MSF), suggesting a common leukemogenic pathway.\",\n      \"method\": \"RT-PCR, sequencing, Southern blot, cytogenetics, FISH\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Strong — molecular characterization replicated across multiple cases and independent labs, fusion transcript and protein structure established\",\n      \"pmids\": [\"11809673\", \"12096348\", \"11477664\", \"18492691\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"The MLL genomic breakpoint in the MLL-SEPTIN6 rearrangement was identified as a functional DNA topoisomerase II cleavage site in an in vitro cleavage assay, implicating topoisomerase II activity in generating the chromosomal translocation.\",\n      \"method\": \"In vitro topoisomerase II cleavage assay, panhandle PCR, Southern blot\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic assay, single lab, replicated in second case\",\n      \"pmids\": [\"12096348\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Sept6-deficient mice showed no gross abnormalities, no cytokinesis defects, and no spontaneous malignancy. Loss of Sept6 did not alter levels of other septins, did not worsen the Sept4-null phenotype, and did not affect the myeloproliferative disease induced by MLL-SEPT6, indicating that SEPT6 does not function as a tumor suppressor and that there is high redundancy within the septin system.\",\n      \"method\": \"Gene knockout (Sept6-deficient mice), bone marrow transplantation, retroviral MLL-SEPT6 expression, in vitro siRNA of Sept11\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO mouse model with multiple phenotypic readouts, epistasis with Sept4-null and MLL-SEPT6 disease model, independent genetic manipulations\",\n      \"pmids\": [\"16314519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"SEPT6 localizes to branch points of developing dendrites and to bases of filopodia and spines in hippocampal neurons, forming ring-like structures (~0.5 μm diameter). SEPT6 is expressed beginning at stage 4 (dendritic outgrowth) and is not a post-synaptic density (PSD) protein. RNAi knockdown of SEPT6 at early developmental stage significantly reduced dendritic length and branch number, demonstrating a role in dendritic cytoarchitecture.\",\n      \"method\": \"Immunocytochemistry, detergent extraction fractionation, RNAi knockdown with morphological quantification in dissociated hippocampal cultures\",\n      \"journal\": \"Molecules and cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — localization tied to functional consequence via RNAi, multiple orthogonal methods, single lab\",\n      \"pmids\": [\"21544625\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"SEPT6 and SEPT7 complexes bound to F-actin regulate protein sorting during multivesicular body (MVB) biogenesis. These complexes bind the AP-3 adaptor complex, modulate AP-3 membrane interactions and motility of AP-3-positive endosomes. SEPT6/SEPT7 interactions also influence membrane association of ESCRT-I, coordinating two cargo-sorting machineries during MVB biogenesis. This coordination requires the E3 ubiquitin ligase LRSAM1.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, live-cell imaging of endosome motility, subcellular fractionation\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, functional knockdown with defined endosomal phenotype, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"25380047\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"SEPT12 interacts with SEPT6 both in vitro and in vivo (in HeLa cells), independently of the SEPT6 coiled-coil domain. Co-expression of SEPT12 altered the filamentous structure of SEPT6 in HeLa cells, demonstrating that septin-septin interactions modulate SEPT6 filament organization.\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding assay, co-expression with fluorescence microscopy in HeLa cells, deletion mutant analysis\",\n      \"journal\": \"Journal of biochemistry and molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro and in vivo binding confirmed, domain mapping, single lab\",\n      \"pmids\": [\"18047794\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LSD1 demethylates the SEPT6 promoter to positively regulate SEPT6 expression at the transcriptional level. LSD1-mediated upregulation of SEPT6 activates the TGF-β1/Smad signaling pathway to promote NSCLC cell proliferation, migration, invasion, and in vivo metastasis.\",\n      \"method\": \"Lentivirus-mediated LSD1 silencing and SEPT6 overexpression, RT-qPCR, western blotting, EdU proliferation assay, Transwell assay, flow cytometry, xenograft mouse model\",\n      \"journal\": \"Cancer gene therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epistatic rescue experiment (LSD1 KD + SEPT6 OE), multiple functional assays, in vivo validation, single lab\",\n      \"pmids\": [\"33664458\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SEPT6 promotes HCC cell proliferation, migration, and invasion by facilitating F-actin formation, which leads to LATS1 dephosphorylation, Hippo pathway inhibition, and YAP nuclear translocation with downstream upregulation of cyclin D1 and MMP2. YAP overexpression rescued SEPT6-knockdown phenotypes and YAP knockdown blocked SEPT6-overexpression effects, placing SEPT6 upstream of YAP in HCC.\",\n      \"method\": \"Stable knockdown/overexpression cell lines, CCK-8, flow cytometry, Transwell assay, YAP rescue and knockdown epistasis, western blotting\",\n      \"journal\": \"International journal of oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis (YAP rescue), multiple functional readouts, single lab\",\n      \"pmids\": [\"33846777\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SEPT6 overexpression in hepatic stellate cells (HSCs) promotes TGF-β1 expression and phosphorylation of Smad2, Smad3, ERK, JNK, SAPK-2, and AKT, driving fibrogenic activation. Blockade of TGF-β1/Smad signaling reversed SEPT6 overexpression effects on α-SMA, cyclin D1, BCL2, and MMP-2/-9. In vivo, adenovirus-mediated SEPT6 inhibition attenuated TAA-induced liver fibrosis in rats.\",\n      \"method\": \"Overexpression/knockdown in HSC lines, pharmacological TGF-β1/Smad blockade (SB431542), in vivo adenovirus-mediated knockdown in rat fibrosis model, western blotting\",\n      \"journal\": \"Laboratory investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pathway blockade epistasis, in vivo validation, multiple signaling readouts, single lab\",\n      \"pmids\": [\"30315255\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"SEPT6-deficient hematopoietic stem cells (HSCs) exhibit increased engraftment potential but impaired lymphoid differentiation, with reduced T-cell and increased B-cell contribution. Multipotent progenitor cells showed distinct SEPT6 filament organization but were functionally unimpaired by SEPT6 deficiency, indicating SEPT6 specifically regulates long-term HSC function and lymphoid lineage choice.\",\n      \"method\": \"Sept6-deficient mouse model, bone marrow transplantation, flow cytometry of hematopoietic lineages, fluorescence microscopy of septin filaments\",\n      \"journal\": \"Experimental hematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO mouse with defined hematopoietic phenotype, multiple lineage readouts, single lab\",\n      \"pmids\": [\"28751190\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"A germline stop-loss mutation in SEPT6 caused X-linked congenital neutropenia with myeloid tetraploidy in a male infant. Reduced SEPT6 staining was found in bone marrow granulocyte precursors and megakaryocytes. SEPT6 KO in an erythroid cell line produced multinucleation. In silico modeling predicted the mutation disrupts SEPT6 coiled-coil dimerization, impairing filament formation. These data establish a critical role for SEPT6 in chromosomal segregation in myeloid progenitors.\",\n      \"method\": \"Next-generation sequencing, CRISPR/Cas9 knock-in and knockout, iPSC myeloid colony assay, immunohistochemistry, in silico structural modeling\",\n      \"journal\": \"American journal of hematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO functional validation, patient-derived iPSC assay, multiple cell-type readouts; in silico structural modeling lowers confidence for the dimerization mechanism\",\n      \"pmids\": [\"34677878\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Zebrafish Sept6-null mutants are viable without gross developmental defects but are more susceptible to Shigella infection, demonstrating a role for Sept6 in host defence against intracellular bacterial pathogens in vivo.\",\n      \"method\": \"CRISPR/Cas9 null mutant generation, in vivo Shigella infection model in zebrafish larvae, survival analysis, RT-qPCR of other septin genes\",\n      \"journal\": \"Cytoskeleton (Hoboken, N.J.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean null mutant with defined infection phenotype, ortholog validation consistent with mammalian SEPT6 function, single lab\",\n      \"pmids\": [\"36855298\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In stored platelets, miR-223 directly targets the 3'UTR of SEPT6 mRNA and downregulates SEPT6 expression. SEPT6 mRNA co-immunoprecipitates with AGO2 in platelet extracts, and a luciferase reporter with SEPT6 3'UTR is downregulated by miR-223, establishing miR-223 as a post-transcriptional regulator of SEPT6 in platelets.\",\n      \"method\": \"AGO2 co-immunoprecipitation, luciferase reporter assay with SEPT6 3'UTR, anti-miR-223 rescue in platelets\",\n      \"journal\": \"MicroRNA (Shariqah, United Arab Emirates)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — AGO2 pull-down plus reporter assay confirms direct miRNA-mRNA interaction, single lab, two orthogonal methods\",\n      \"pmids\": [\"29943706\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SEPT6 undergoes liquid-liquid phase separation (LLPS) both in vitro and in vivo in polarized epithelial (MDCK) cells, mediated by weak, multivalent interactions through its C-terminal tail. SEPT6 mutants defective in LLPS in vitro also fail to support adherens junction integrity and cell polarity establishment in 2D and 3D cultures, demonstrating that LLPS-competent SEPT6 is required for epithelial polarity.\",\n      \"method\": \"In vitro LLPS assay, live-cell imaging of septin dynamics in MDCK cells, SEPT6 C-terminal tail mutant analysis, 3D lumen formation assay\",\n      \"journal\": \"Journal of molecular cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro reconstitution of LLPS plus cell-based mutant rescue, multiple orthogonal methods, single lab\",\n      \"pmids\": [\"39973116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SEPT6 acts upstream of UBC (ubiquitin C) in prostate cancer cells: SEPT6 overexpression decreased UBC expression while SEPT6 knockdown increased it, and SEPT6 co-localizes with UBC in prostate cancer cells by immunofluorescence. SEPT6 inhibited tumor growth in vivo through this UBC-mediated reduction of overall ubiquitination levels.\",\n      \"method\": \"Overexpression/knockdown, immunofluorescence co-localization, CCK-8, flow cytometry, xenograft tumor formation\",\n      \"journal\": \"Mediators of inflammation\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — co-localization only (no direct binding assay), epistasis based on expression levels, single lab, no biochemical interaction confirmation\",\n      \"pmids\": [\"34966246\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"SEPT6 overexpression in dairy cow mammary epithelial cells upregulates mTOR, p-mTOR, S6K1, and p-S6K1, promoting cell growth and casein (CSN2) synthesis. mTOR inhibition blocked the effects of SEPT6 overexpression, placing SEPT6 upstream of the mTORC1 pathway in amino acid-mediated casein synthesis.\",\n      \"method\": \"Overexpression/inhibition of SEPT6, mTOR inhibition rescue, western blotting, cell growth assays in primary dairy cow mammary epithelial cells\",\n      \"journal\": \"The Journal of dairy research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single cell type (non-human), epistasis based on pharmacological inhibition only, no direct binding shown\",\n      \"pmids\": [\"31122298\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SEPTIN6 is a GTP-binding cytoskeletal protein that functions as a scaffold within heteropolymeric septin complexes (e.g., SEPT2/6/7), undergoes liquid-liquid phase separation via its C-terminal tail to support epithelial polarity and adherens junction integrity, localizes to dendritic branch points and spine bases to regulate neuronal cytoarchitecture, participates in AP-3/ESCRT-dependent MVB biogenesis by binding F-actin-associated SEPT7 complexes, facilitates HCV replication through interaction with NS5b and hnRNP A1, is regulated post-transcriptionally by miR-223/AGO2 and transcriptionally by LSD1-mediated promoter demethylation, plays a non-redundant role in chromosomal segregation in myeloid progenitors and lymphoid differentiation of hematopoietic stem cells, and is recurrently fused to MLL (KMT2A) in infant AML via translocations at a topoisomerase II cleavage site, generating a leukemogenic fusion protein.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SEPTIN6 is a GTP-binding cytoskeletal protein that assembles into heteromeric septin filaments and serves as a membrane- and actin-associated scaffold supporting cytoarchitecture across diverse cell types [#6, #4]. Within neurons, SEPT6 localizes to dendritic branch points and the bases of filopodia and spines as ring-like structures and is required for dendritic outgrowth and branching [#4]. It engages partner septins through interactions distinct from its coiled-coil domain, and these septin-septin contacts remodel SEPT6 filament organization [#6]. SEPT6 self-organization extends to liquid-liquid phase separation driven by weak multivalent interactions of its C-terminal tail, a property required to maintain adherens junction integrity and epithelial polarity [#14]. In membrane trafficking, F-actin-bound SEPT6/SEPT7 complexes bind the AP-3 adaptor and influence ESCRT-I membrane association, coordinating cargo sorting during multivesicular body biogenesis in an LRSAM1-dependent manner [#5]. SEPT6 has a non-redundant role in hematopoiesis, regulating long-term HSC function and lymphoid lineage choice [#10], and in chromosomal segregation of myeloid progenitors, where a germline stop-loss mutation causes X-linked congenital neutropenia with myeloid tetraploidy [#11]. SEPT6 also contributes to host defense against intracellular bacteria [#12] and is exploited by hepatitis C virus, binding the NS5b RNA-dependent RNA polymerase and hnRNP A1 to support viral RNA replication [#0]. Across epithelial cancers and fibrosis, SEPT6 acts upstream of pro-proliferative signaling, promoting F-actin formation to inhibit the Hippo pathway and drive YAP nuclear translocation [#8] and activating TGF-\\u03b21/Smad signaling [#9]. SEPT6 expression is controlled post-transcriptionally by miR-223/AGO2 [#13] and transcriptionally by LSD1-mediated promoter demethylation [#7]. SEPTIN6 is recurrently fused to MLL (KMT2A) in infant acute myeloid leukemia via t(X;11)(q24;q23) at a topoisomerase II cleavage site, generating an MLL-SEPT6 leukemogenic fusion protein [#1, #2].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Establishing how SEPTIN6 contributes to leukemia, this work showed it is recurrently fused to MLL in infant AML, producing a fusion protein incorporating nearly the entire septin sequence.\",\n      \"evidence\": \"RT-PCR, sequencing, cytogenetics and FISH across multiple infant AML cases\",\n      \"pmids\": [\"11809673\", \"12096348\", \"11477664\", \"18492691\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not define the biochemical activity of the MLL-SEPT6 fusion protein\", \"Mechanism of leukemogenic transformation not resolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Addressing why this specific translocation arises, the MLL breakpoint was shown to be a functional topoisomerase II cleavage site, implicating enzymatic DNA cleavage in generating the rearrangement.\",\n      \"evidence\": \"In vitro topoisomerase II cleavage assay with panhandle PCR and Southern blot\",\n      \"pmids\": [\"12096348\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vitro assay does not prove topoisomerase II generates the break in vivo\", \"Single-lab characterization\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Testing whether SEPT6 acts as a tumor suppressor or essential cytokinesis factor, knockout mice revealed extensive septin redundancy and no requirement for SEPT6 in normal development or MLL-SEPT6-driven disease.\",\n      \"evidence\": \"Sept6-deficient mice with bone marrow transplantation, retroviral MLL-SEPT6 expression, and Sept4-null epistasis\",\n      \"pmids\": [\"16314519\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Redundancy obscures any SEPT6-specific function under unstressed conditions\", \"Does not address tissue-specific or context-dependent roles\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Connecting SEPT6 to viral pathogenesis, it was identified as an NS5b and hnRNP A1 interactor required for efficient HCV RNA replication.\",\n      \"evidence\": \"Yeast two-hybrid, co-immunoprecipitation, siRNA knockdown and dominant-negative overexpression\",\n      \"pmids\": [\"17229681\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular role of SEPT6 in the replication complex undefined\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"To understand how SEPT6 filaments are organized, SEPT12 was shown to bind SEPT6 independently of its coiled-coil and to remodel its filamentous structure, demonstrating septin-septin regulation of assembly.\",\n      \"evidence\": \"In vitro binding, co-IP, co-expression microscopy and deletion mapping in HeLa cells\",\n      \"pmids\": [\"18047794\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of SEPT6-SEPT12 filaments not established\", \"Stoichiometry within native septin complexes unknown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defining a neuronal function, SEPT6 was localized to dendritic branch points and spine/filopodia bases and shown to be required for dendritic outgrowth and branching.\",\n      \"evidence\": \"Immunocytochemistry, fractionation and RNAi with morphological quantification in hippocampal neurons\",\n      \"pmids\": [\"21544625\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism linking septin rings to dendrite morphology unclear\", \"Partners at branch points not identified\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Linking SEPT6 to membrane trafficking, F-actin-bound SEPT6/SEPT7 complexes were shown to coordinate AP-3 and ESCRT-I machineries during MVB biogenesis.\",\n      \"evidence\": \"Reciprocal co-IP, siRNA knockdown, live-cell endosome imaging and fractionation\",\n      \"pmids\": [\"25380047\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How septins physically bridge AP-3 and ESCRT-I is unresolved\", \"Role of LRSAM1 mechanistically undefined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Resolving a non-redundant hematopoietic role, SEPT6-deficient HSCs showed increased engraftment but impaired lymphoid differentiation, establishing SEPT6 control of long-term HSC function and lineage choice.\",\n      \"evidence\": \"Sept6-deficient mouse model with bone marrow transplantation and flow cytometry of lineages\",\n      \"pmids\": [\"28751190\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of biased lineage output unknown\", \"Reconciliation with earlier redundancy data not addressed\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Establishing post-transcriptional control, miR-223 was shown to directly target the SEPT6 3'UTR via AGO2 to downregulate SEPT6 in platelets.\",\n      \"evidence\": \"AGO2 co-IP, luciferase 3'UTR reporter and anti-miR-223 rescue in stored platelets\",\n      \"pmids\": [\"29943706\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of SEPT6 loss in platelets not defined\", \"Whether this regulation operates outside platelets unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Implicating SEPT6 in fibrosis signaling, its overexpression in hepatic stellate cells was shown to drive TGF-\\u03b21/Smad-dependent fibrogenic activation in vitro and in vivo.\",\n      \"evidence\": \"Overexpression/knockdown, pharmacological TGF-\\u03b21/Smad blockade and adenoviral knockdown in a rat fibrosis model\",\n      \"pmids\": [\"30315255\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular link between SEPT6 and TGF-\\u03b21 induction not defined\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Connecting transcriptional regulation to cancer, LSD1 was shown to demethylate the SEPT6 promoter to upregulate SEPT6 and activate TGF-\\u03b21/Smad signaling, promoting NSCLC progression.\",\n      \"evidence\": \"Lentiviral LSD1 silencing and SEPT6 overexpression with functional assays and xenografts\",\n      \"pmids\": [\"33664458\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding of LSD1 to the SEPT6 promoter not demonstrated mechanistically\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Placing SEPT6 in oncogenic signaling, it was shown to promote F-actin formation that inhibits the Hippo pathway and drives YAP nuclear translocation in HCC.\",\n      \"evidence\": \"Stable knockdown/overexpression with YAP rescue and knockdown epistasis and functional assays\",\n      \"pmids\": [\"33846777\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How SEPT6/F-actin regulates LATS1 phosphorylation is undefined\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defining a Mendelian disease link, a germline stop-loss mutation was shown to cause X-linked congenital neutropenia with myeloid tetraploidy, establishing SEPT6 in chromosomal segregation of myeloid progenitors.\",\n      \"evidence\": \"NGS, CRISPR knock-in/knockout, patient iPSC myeloid colony assays and in silico structural modeling\",\n      \"pmids\": [\"34677878\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Dimerization-disruption mechanism rests on in silico modeling\", \"Single patient case\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"A proposed prostate cancer role placed SEPT6 upstream of ubiquitin C to reduce ubiquitination and inhibit tumor growth.\",\n      \"evidence\": \"Overexpression/knockdown, immunofluorescence co-localization and xenograft assays\",\n      \"pmids\": [\"34966246\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Co-localization only; no direct SEPT6-UBC binding assay\", \"Epistasis inferred from expression changes alone\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extending function to host defense, zebrafish Sept6-null mutants were viable but more susceptible to Shigella, demonstrating an in vivo role against intracellular bacteria.\",\n      \"evidence\": \"CRISPR/Cas9 null mutant zebrafish with in vivo Shigella infection and survival analysis\",\n      \"pmids\": [\"36855298\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of septin-mediated bacterial restriction not defined\", \"Conservation to mammalian SEPT6 inferred, not tested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defining a biophysical mechanism, SEPT6 was shown to undergo C-terminal-tail-driven liquid-liquid phase separation that is required for adherens junction integrity and epithelial polarity.\",\n      \"evidence\": \"In vitro LLPS reconstitution and C-terminal mutant rescue in MDCK 2D/3D cultures with live imaging\",\n      \"pmids\": [\"39973116\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How LLPS integrates with canonical septin filament assembly unclear\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how SEPT6's distinct activities — filament scaffolding, LLPS, trafficking coordination, and chromosomal segregation — are partitioned across cell types, and what biochemical activity the MLL-SEPT6 fusion confers in leukemogenesis.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of native SEPT6 heteropolymers in human cells\", \"Mechanism of MLL-SEPT6 transformation unresolved\", \"Direct enzymatic/GTPase role of SEPT6 not functionally dissected in the corpus\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [5, 8]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [4, 6, 14]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [4, 6]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [8, 9]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1, 11]}\n    ],\n    \"complexes\": [\"SEPT6/SEPT7 complex\", \"MLL-SEPT6 fusion\"],\n    \"partners\": [\"SEPT7\", \"SEPT12\", \"NS5B\", \"HNRNPA1\", \"AGO2\", \"KMT2A\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":10,"faith_total":10,"faith_pct":100.0}}