{"gene":"CYTH1","run_date":"2026-06-09T22:57:19","timeline":{"discoveries":[{"year":1996,"finding":"Cytohesin-1 specifically interacts with the intracellular portion of the integrin β2 chain (CD18) and overexpression of full-length cytohesin-1 or its SEC7 domain induces β2 integrin-dependent binding of Jurkat cells to ICAM-1, while expression of the isolated PH domain inhibits T cell receptor-stimulated adhesion.","method":"Co-interaction assay with integrin β2 cytoplasmic domain; overexpression and dominant-negative studies in Jurkat cells measuring ICAM-1 adhesion","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal functional analysis with multiple constructs (full-length, SEC7 domain, PH domain) across multiple groups, seminal paper replicated by many subsequent studies","pmids":["8706128"],"is_preprint":false},{"year":1997,"finding":"Cytohesin-1 functions as a guanine nucleotide-exchange protein (GEP) for ARF GTPases, accelerating GDP-to-GTP exchange on ARF1 and ARF3 purified from bovine brain; this GEP activity is not inhibited by brefeldin A, distinguishing it from BFA-sensitive ARF-GEPs.","method":"In vitro GEP assay with recombinant cytohesin-1 (expressed in E. coli) and purified ARF; [35S]GTPγS binding and [3H]GDP release assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro reconstitution assay with purified proteins, replicated by multiple subsequent biochemical studies","pmids":["9050849"],"is_preprint":false},{"year":1998,"finding":"Constitutively active PI 3-kinase is sufficient to activate Jurkat cell adhesion to ICAM-1 and induces membrane recruitment of cytohesin-1; this effect requires the cytohesin-1 PH domain, placing PI 3-kinase upstream of cytohesin-1 in the β2 integrin inside-out signaling pathway.","method":"Overexpression of constitutively active PI 3-kinase; dominant-negative PH domain constructs; membrane fractionation to assess cytohesin-1 localization; adhesion assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — epistasis established by gain-of-function and dominant-negative approaches with defined cellular readout; replicated across multiple labs","pmids":["9614087"],"is_preprint":false},{"year":1998,"finding":"Both the PH domain and the adjacent C-terminal polybasic (c) domain of cytohesin-1 are required together for high-affinity (100 nM) binding to PI(3,4,5)P3 and for plasma membrane association and biological function; the isolated PH domain has substantially lower affinity (~2–3 µM) for PI(3,4,5)P3.","method":"Biosensor affinity measurements; deletion/chimeric mutant expression in Jurkat cells; membrane association assays; functional adhesion assays","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro binding quantified by biosensor combined with mutational analysis and functional cellular assays in a single study","pmids":["9693361"],"is_preprint":false},{"year":1998,"finding":"NMR solution structure of the cytohesin-1 Sec7 domain reveals 10 α-helices forming a unique fold; ARF1 binding occurs through a large surface on the C-terminal subdomain involving hydrophobic and polar residues; structure-based mutagenesis identified residues critical for ARF binding and nucleotide exchange. However, the Sec7 domain and the β2 integrin cytoplasmic domain do not interact in solution phase.","method":"NMR spectroscopy; 1H-15N and 1H-13C chemical shift perturbation mapping; structure-based mutagenesis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — NMR structure with functional mutagenesis validation in a single rigorous study","pmids":["9653114"],"is_preprint":false},{"year":1998,"finding":"The cytohesin-1 Sec7 domain catalyzes guanine nucleotide exchange on ARFs 1, 5, and 6, yeast ARFs 1–3, and ARD1; full-length cytohesin-1 shows narrower substrate specificity (active on ARF1, ARF3, and ARD1 but not ARF5/6), indicating that regions outside the Sec7 domain contribute to substrate specificity. Neither acts on ARF-like (ARL) proteins.","method":"In vitro GTPγS binding assays with purified recombinant proteins; comparison of Sec7 domain alone vs. full-length cytohesin-1 across a panel of ARF/ARL substrates","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic in vitro reconstitution across multiple substrates with purified proteins","pmids":["9756891"],"is_preprint":false},{"year":1999,"finding":"Cytohesin-1 PH domain binds the inositol head group of PI(3,4,5)P3 (as IP4) with >200-fold higher affinity than PI(4,5)P2 or PI(3,4)P2 in vitro; EGF- or NGF-stimulated translocation of GFP-cytohesin-1 from cytosol to plasma membrane in PC12 cells requires PI 3-kinase activity and an intact PH domain.","method":"In vitro PH domain-lipid binding assays; GFP-cytohesin-1 live-cell confocal microscopy in PC12 cells; wortmannin/LY294002 inhibition; dominant-negative p85 co-expression","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro binding with quantitative affinity measurement combined with live-cell imaging and PI3K inhibitor/dominant-negative validation","pmids":["10341214"],"is_preprint":false},{"year":1999,"finding":"Structural elements in ARF1 required for functional interaction with cytohesin-1 include the N-terminal α-helix (residues 1–13), switch 1 region (residues 28–50, including Lys-38), and C-terminal region (last 42 amino acids); replacing Lys-38 with Gln abolishes the interaction with both cytohesin-1 and its Sec7 domain.","method":"ARF1/ARL1 chimeric protein panel; site-directed mutagenesis; in vitro [35S]GTPγS binding assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic in vitro mutagenesis and chimera analysis with reconstituted exchange activity","pmids":["10212218"],"is_preprint":false},{"year":1999,"finding":"Cytohesin-1 is required for LPS-induced β2 integrin (LFA-1)-mediated monocyte adherence to ICAM-1 downstream of CD14, Rho, and PI 3-kinase; antisense knockdown of cytohesin-1 abrogates LPS-induced adherence without affecting LFA-1 surface expression.","method":"Cytohesin-1 antisense oligonucleotides in THP-1/CD14 cells; PI 3-kinase inhibitors; Toxin B (Rho inhibitor); ICAM-1 adhesion assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — antisense knockdown with functional adhesion readout and pathway inhibitors; single lab but multiple pathway perturbations","pmids":["9873050"],"is_preprint":false},{"year":2000,"finding":"Cytohesin-1 regulates β2 integrin adhesion through two separable mechanisms: (1) direct interaction with the LFA-1 β2 cytoplasmic domain activates an extracellular epitope of LFA-1 independent of ARF-GEF activity; (2) ARF-GEF activity is required for LFA-1-mediated cell spreading on ICAM-1. A GEF-dead mutant of cytohesin-1 blocks spreading but not initial LFA-1 activation.","method":"Mutational analysis of β2 cytoplasmic domain; cytohesin-1 GEF-dead mutant (E157K); in vitro ARF GDP-GTP exchange assays; LFA-1 activation epitope detection; cell adhesion and spreading assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — combined in vitro GEF assay with mutagenesis and multiple cellular functional readouts dissecting two distinct mechanisms","pmids":["10835351"],"is_preprint":false},{"year":2000,"finding":"PI(3,4,5)P3 differentially regulates cytohesin-1 GEF specificity: it suppresses cytohesin-1-dependent GTP binding to ARF6-Ig chimeras while enhancing GTP binding to ARF1-Ig chimeras, thereby switching ARF substrate specificity of cytohesin-1.","method":"In vitro GTP-binding assays using immunoprecipitated ARF1-Ig and ARF6-Ig chimeras from mammalian cells; addition of purified phosphoinositides","journal":"European journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro functional assay with defined lipid additions, single lab, single method","pmids":["10848997"],"is_preprint":false},{"year":2000,"finding":"Cytohesin-1 specifically accelerates GTPγS binding to ARD1 (a 64-kDa lysosomal/Golgi GTPase) but not cytohesin-2; the specificity is determined by residue 30 in the Sec7 domain and the ARD1 effector region; in COS-7 cells, overexpressed ARD1 and cytohesin-1 partially colocalize.","method":"Yeast two-hybrid screen (ARD1 as bait); in vitro [35S]GTPγS binding assays; Sec7 domain point mutagenesis; confocal fluorescence microscopy of co-transfected COS-7 cells","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — yeast two-hybrid plus in vitro GEF assay plus mutagenesis plus colocalization; single lab","pmids":["10748148"],"is_preprint":false},{"year":2000,"finding":"B2-1/cytohesin-1 localizes to the Golgi complex (not primarily the plasma membrane) under endogenous expression conditions; this Golgi association is disrupted by brefeldin A; overexpression of GFP-B2-1 shows Golgi targeting and excessive overexpression causes partial Golgi dispersion.","method":"Immunofluorescence localization; brefeldin A treatment; transient transfection of GFP-tagged B2-1; confocal microscopy","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct localization by imaging with BFA perturbation; single lab, single approach","pmids":["10772823"],"is_preprint":false},{"year":2001,"finding":"Protein kinase Cδ phosphorylates a serine/threonine motif within the C-terminal polybasic domain of cytohesin-1 in vitro; phorbol ester stimulation also induces phosphorylation of these residues in vivo; PKC-phosphorylated cytohesin-1 associates tightly with the actin cytoskeleton and phosphorylation is required for maximal LFA-1-mediated Jurkat cell adhesion to ICAM-1.","method":"In vitro kinase assay with purified PKCδ; phorbol ester stimulation in vivo; co-sedimentation with actin cytoskeleton; site-directed mutagenesis; adhesion assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro kinase assay plus in vivo phosphorylation confirmed plus cytoskeletal fractionation plus functional adhesion readout with mutagenesis","pmids":["11438522"],"is_preprint":false},{"year":2001,"finding":"Human herpesvirus 8 kaposin A directly interacts with cytohesin-1 and recruits it to the membrane; this interaction mediates kaposin A-induced focus formation, stress fiber dissolution, and ERK-1/2 MAP kinase activation; these effects are reversed by the GEF-dead cytohesin-1 E157K mutant; liposome-embedded kaposin A specifically stimulates cytohesin-1-dependent GTP binding to myristoylated ARF1 in vitro.","method":"Co-immunoprecipitation; dominant-negative GEF mutant (E157K) rescue; in vitro ARF GTP-binding assay with liposome-embedded kaposin A; focus formation and stress fiber assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro reconstitution combined with Co-IP, mutagenesis rescue, and multiple cellular phenotype readouts","pmids":["11336706"],"is_preprint":false},{"year":2001,"finding":"Cytohesin-1 overexpression increases LFA-1-dependent leukocyte arrest triggered by chemokines on cytokine-activated endothelium; the PH domain (not GEF activity) mediates firm arrest, while both LFA-1 interaction and GEF activity are required for shape change and transendothelial chemotaxis; ARF6 (but not ARF1) participates as downstream GEF target in chemotaxis.","method":"Overexpression and dominant-negative constructs (PH domain, GEF-dead mutant, β2 cytoplasmic domain mutant) in flow-based leukocyte adhesion assays on endothelium; transendothelial migration assays; ARF6 dominant-negative rescue","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple dominant-negative constructs dissecting pathway, physiologically relevant flow assay; single lab","pmids":["11747824"],"is_preprint":false},{"year":2002,"finding":"Cybr (a cytokine-inducible protein related to GRASP) physically interacts with cytohesin-1 via coiled-coil domain interactions and enhances cytohesin-1-catalyzed GTPγS binding to ARF in vitro.","method":"Co-immunoprecipitation of overexpressed proteins from 293T cells; in vitro ARF GEP activity assay with recombinant Cybr","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus in vitro GEF activity assay; single lab, two orthogonal methods","pmids":["11867758"],"is_preprint":false},{"year":2003,"finding":"LFA-1 activation induces phosphorylation of the β2 integrin chain, releases JAB-1, and mediates ERK1/2 signaling through cytohesin-1; dominant-negative cytohesin-1 inhibits IL-2 production and impairs Th1 differentiation.","method":"Intracellular phosphoprotein staining with 13-dimensional flow cytometry; dominant-negative cytohesin-1 expression; cytokine production assays","journal":"Nature immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — phosphoprotein flow cytometry combined with dominant-negative functional readouts; single lab, multiple orthogonal assays","pmids":["14528303"],"is_preprint":false},{"year":2005,"finding":"CD14-regulated complement receptor 3 (CR3/Mac-1)-dependent phagocytosis of mycobacteria requires cytohesin-1; cytohesin-1 physically associates with CR3 upon stimulation with mycobacterial surface components; knockdown of cytohesin-1 specifically abrogates CD14-regulated CR3-mediated BCG internalization.","method":"siRNA knockdown of cytohesin-1; PI3K inhibitors; blocking antibodies; flow cytometry phagocytosis assay; co-immunoprecipitation of CR3 and cytohesin-1","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with specific phagocytosis readout plus physical association by Co-IP; single lab","pmids":["15778383"],"is_preprint":false},{"year":2009,"finding":"Cytohesin-1 specifically activates Arf6 (but not Arf1) in fMLP-stimulated human neutrophils; cytohesin-1/Arf6 signaling drives phospholipase D activation, NADPH oxidase-dependent superoxide production, and degranulation; SecinH3 (selective cytohesin Sec7 inhibitor) blocks these responses, as does cytohesin-1 siRNA knockdown.","method":"SecinH3 pharmacological inhibition; siRNA knockdown; stable overexpression in PLB-985 cells; Arf6 and Arf1 activation assays; PLD activity assay; superoxide production assay; surface granule marker expression by flow cytometry","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — pharmacological inhibition, siRNA, and stable overexpression all converge on same phenotype with multiple functional readouts; single lab with multiple orthogonal approaches","pmids":["20018626"],"is_preprint":false},{"year":2012,"finding":"The Src-family kinase Fyn phosphorylates cytohesin-1 at tyrosine 382 (Y382); this phosphorylation is required for full myelination by Schwann cells. Transgenic mice expressing a Schwann cell-specific Y382F phosphorylation-deficient cytohesin-1 show delayed myelination and reduced myelin thickness similar to cytohesin-1 knockout mice.","method":"In vitro kinase assay (Fyn + cytohesin-1); phosphorylation-deficient transgenic mice (Y382F, Schwann cell-specific); cytohesin-1 knockout mice; electron microscopy of peripheral nerves","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro kinase assay with mutagenesis plus in vivo genetic rescue in two independent mouse models converging on same phenotype","pmids":["23012656"],"is_preprint":false},{"year":2013,"finding":"Cytohesin-1 and its downstream GTPase Arf6 are required for peripheral neuronal conditioned medium-stimulated migration of primary Schwann cells; the Y382 residue (Fyn phosphorylation site) is required for migration since Y382F cytohesin-1 fails to rescue migration in siRNA-transfected cells.","method":"siRNA knockdown of cytohesin-1 and Arf6; SecinH3 inhibitor; cytohesin-1 knockout Schwann cells; reintroduction of siRNA-resistant wild-type vs. Y382F cytohesin-1; transwell migration assay","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA + inhibitor + KO + rescue with mutant; single lab, multiple convergent approaches","pmids":["23517829"],"is_preprint":false},{"year":2013,"finding":"Schwann cell-specific overexpression of wild-type cytohesin-1 in transgenic mice produces enhanced myelin thickness in peripheral nerves and elevated downstream Arf6 activation, confirming cytohesin-1 promotes myelination in vivo through the cytohesin-1/Arf6 signaling axis.","method":"Schwann cell-specific transgenic overexpression of cytohesin-1; electron microscopy morphometry of peripheral nerves; Arf6 activation assay","journal":"Journal of molecular neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo transgenic gain-of-function with morphometric and biochemical readouts; single lab","pmids":["23636892"],"is_preprint":false},{"year":2016,"finding":"CYTH1 knockdown disrupts adhesion of human cord blood hematopoietic stem and progenitor cells (HSPCs) to mesenchymal stroma cells, fibronectin, and ICAM-1/2, reduces integrin β1 activation, impairs bone marrow homing after transplantation into immunodeficient mice, and impairs HSPC lodgment in the marrow niche as shown by intravital microscopy.","method":"RNAi screen; shRNA knockdown; adhesion assays; integrin β1 activation assay; xenograft transplantation; intravital microscopy","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Moderate — siRNA/shRNA with multiple orthogonal readouts (adhesion assays, in vivo engraftment, intravital microscopy); single lab but comprehensive mechanistic analysis","pmids":["27899358"],"is_preprint":false},{"year":2018,"finding":"A microexon-encoded triglycine vs. diglycine difference in the cytohesin-1 PH domain determines differential phosphoinositide affinity (triglycine for PI(4,5)P2, diglycine for PI(3,4,5)P3); this distinction produces distinct subcellular localizations (triglycine to plasma membrane, diglycine to leading edge) and controls Met RTK-dependent cell migration, where the diglycine/PI(3,4,5)P3-binding isoform is specifically required.","method":"Alternative splicing microexon analysis; phosphoinositide binding assays; live-cell imaging of GFP-tagged isoforms; HGF/Met-stimulated migration assays; isoform-specific knockdown and rescue","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro lipid binding combined with live-cell imaging, isoform-specific knockdown and rescue with defined localization and functional readouts","pmids":["30404949"],"is_preprint":false},{"year":2023,"finding":"CYTH1 depletion or inhibition with SecinH3 inhibits adhesion, migration, homing, and engraftment of AML leukemic cells in vivo; targeting CYTH1 suppresses integrin-associated adhesion signaling by reducing ITGB2 expression and reduces anti-apoptotic MCL1; SecinH3 synergizes with BCL2-inhibitor venetoclax in ABT-199-resistant AML cells.","method":"CYTH1 shRNA knockdown; SecinH3 pharmacological inhibition; AML cell line proliferation and apoptosis assays; AML xenograft mouse model; Western blotting for signaling components","journal":"Acta pharmacologica Sinica","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — shRNA and pharmacological inhibition in vitro and in vivo with multiple functional and molecular readouts; single lab","pmids":["37644132"],"is_preprint":false}],"current_model":"Cytohesin-1 is a Sec7-domain-containing guanine nucleotide exchange factor (GEF) for ARF GTPases (primarily ARF1 and ARF6) that is recruited to the plasma membrane via cooperative high-affinity PI(3,4,5)P3 binding by its PH domain and C-terminal polybasic domain downstream of PI 3-kinase; it directly engages the β2 integrin cytoplasmic domain to activate LFA-1-mediated cell adhesion through two separable mechanisms—integrin conformational activation (GEF-independent) and ARF-GEF-dependent cytoskeletal remodeling and cell spreading—and is regulated by PKCδ phosphorylation (promoting actin cytoskeleton association) and Fyn-mediated phosphorylation at Y382 (required for Schwann cell myelination and migration via Arf6 activation); a microexon-encoded PH domain isoform further tunes PI(3,4,5)P3 versus PI(4,5)P2 selectivity to spatially restrict Arf6 signaling during RTK-driven cell migration."},"narrative":{"mechanistic_narrative":"Cytohesin-1 (CYTH1) is a Sec7-domain guanine nucleotide exchange factor (GEF) for ARF GTPases that couples phosphoinositide 3-kinase signaling to integrin-mediated cell adhesion, cytoskeletal remodeling, and cell migration [PMID:9050849, PMID:9614087, PMID:10835351]. It accelerates GDP-to-GTP exchange on ARF1, ARF3, and ARF6 in a brefeldin A-insensitive manner, with the isolated Sec7 domain acting on a broader ARF panel than the full-length protein, indicating that flanking regions tune substrate specificity [PMID:9050849, PMID:9756891]; the Sec7 fold engages ARF1 through its C-terminal subdomain, and exchange requires the ARF1 N-terminal helix, switch 1 (Lys-38), and C-terminus [PMID:9653114, PMID:10212218]. Membrane recruitment downstream of PI 3-kinase depends on cooperative high-affinity PI(3,4,5)P3 binding by the PH domain together with the adjacent C-terminal polybasic domain [PMID:9614087, PMID:9693361, PMID:10341214]. Cytohesin-1 directly binds the integrin β2 (CD18) cytoplasmic domain and activates LFA-1-mediated adhesion through two separable mechanisms: a GEF-independent conformational activation of LFA-1 and a GEF-dependent program of cell spreading [PMID:8706128, PMID:10835351]. Through these activities it drives leukocyte arrest and transendothelial migration, monocyte and HSPC adhesion and homing, CR3-dependent phagocytosis, and neutrophil ARF6-driven PLD activation, superoxide production, and degranulation [PMID:11747824, PMID:27899358, PMID:15778383, PMID:20018626]. Its activity is regulated by PKCδ phosphorylation of the polybasic domain, which promotes actin cytoskeleton association, and by Fyn-mediated phosphorylation at Tyr-382, which is required for Schwann cell myelination and migration via Arf6 [PMID:11438522, PMID:23012656, PMID:23517829]. A microexon-encoded PH domain variation switches PI(3,4,5)P3 versus PI(4,5)P2 selectivity to spatially restrict Arf6 signaling during RTK-driven migration [PMID:30404949]. CYTH1 also supports leukemic cell adhesion, homing, and survival, where its inhibition reduces ITGB2 and MCL1 [PMID:37644132].","teleology":[{"year":1996,"claim":"Established cytohesin-1 as a physical and functional link between an integrin cytoplasmic tail and inside-out adhesion signaling, answering how LFA-1 adhesiveness might be controlled intracellularly.","evidence":"Integrin β2 cytoplasmic domain interaction assays and overexpression/dominant-negative constructs in Jurkat cells with ICAM-1 adhesion readout","pmids":["8706128"],"confidence":"High","gaps":["Did not define the biochemical activity of the SEC7 domain","Mechanism of how PH domain inhibits adhesion unresolved"]},{"year":1997,"claim":"Defined the molecular activity of cytohesin-1 as a brefeldin A-insensitive ARF-GEF, identifying the enzymatic basis for its downstream effects.","evidence":"In vitro [35S]GTPγS binding and [3H]GDP release assays with recombinant cytohesin-1 and purified ARF1/ARF3","pmids":["9050849"],"confidence":"High","gaps":["Did not connect GEF activity to adhesion phenotype","ARF6 not yet tested"]},{"year":1998,"claim":"Placed PI 3-kinase upstream of cytohesin-1 and defined the lipid-binding module governing membrane recruitment, establishing the signaling logic of the pathway.","evidence":"Constitutively active PI3K and dominant-negative PH constructs with membrane fractionation and adhesion assays; biosensor affinity measurements of PH plus polybasic domain binding to PI(3,4,5)P3","pmids":["9614087","9693361"],"confidence":"High","gaps":["In vivo PI(3,4,5)P3 dynamics not visualized at this stage","Whether membrane recruitment alone suffices for activation unresolved"]},{"year":1998,"claim":"Resolved the Sec7 domain structure and ARF substrate range, distinguishing intrinsic catalytic specificity from full-length regulation and showing the Sec7 domain does not bind the integrin tail directly.","evidence":"NMR solution structure with chemical shift perturbation mapping and structure-based mutagenesis; in vitro GTPγS assays across an ARF/ARL panel comparing Sec7 domain to full-length protein","pmids":["9653114","9756891"],"confidence":"High","gaps":["Structural basis of the integrin-binding interface not identified","Determinants outside Sec7 that narrow specificity not mapped"]},{"year":1999,"claim":"Confirmed PI(3,4,5)P3-selective PH binding drives PI3K-dependent membrane translocation in response to RTK stimulation and mapped the ARF1 surfaces required for productive exchange.","evidence":"In vitro PH-lipid affinity assays and GFP-cytohesin-1 imaging in EGF/NGF-stimulated PC12 cells with PI3K inhibitors; ARF1/ARL1 chimera and Lys-38 mutagenesis with in vitro exchange assays","pmids":["10341214","10212218"],"confidence":"High","gaps":["Did not address ARF6-specific recruitment","Effector consequences downstream of activated ARF not defined"]},{"year":1999,"claim":"Demonstrated a physiological requirement for cytohesin-1 in LPS-induced, PI3K- and Rho-dependent monocyte adhesion, extending its role beyond T cells.","evidence":"Antisense knockdown in THP-1/CD14 cells with Rho and PI3K inhibitors and ICAM-1 adhesion assays","pmids":["9873050"],"confidence":"Medium","gaps":["Single antisense approach without genetic rescue","Direct molecular link to CD14 not established"]},{"year":2000,"claim":"Dissected adhesion into a GEF-independent LFA-1 conformational activation step and a GEF-dependent spreading step, clarifying how one protein controls two adhesion outputs.","evidence":"β2 tail mutants and GEF-dead E157K cytohesin-1 with in vitro exchange assays, activation-epitope detection, and adhesion/spreading assays","pmids":["10835351"],"confidence":"High","gaps":["Identity of the spreading-relevant ARF in vivo not pinned down","How direct binding triggers conformational change mechanistically unclear"]},{"year":2000,"claim":"Showed phosphoinositides and accessory targets modulate cytohesin-1 ARF preference, adding regulatory and substrate complexity to the GEF.","evidence":"In vitro GTP-binding assays with ARF1-Ig/ARF6-Ig chimeras and added phosphoinositides; yeast two-hybrid, in vitro exchange, Sec7 mutagenesis, and COS-7 colocalization with ARD1; Golgi localization by immunofluorescence with BFA","pmids":["10848997","10748148","10772823"],"confidence":"Medium","gaps":["Lipid-driven specificity switch shown only in vitro with chimeric substrates","Endogenous Golgi versus plasma membrane balance not reconciled across cell types"]},{"year":2001,"claim":"Identified post-translational and pathogen-driven regulation: PKCδ phosphorylation links cytohesin-1 to the actin cytoskeleton, and kaposin A hijacks its GEF activity to remodel cells.","evidence":"In vitro PKCδ kinase assay with in vivo phorbol ester phosphorylation, actin co-sedimentation, and adhesion assays; Co-IP, E157K rescue, and liposome-embedded kaposin A in vitro ARF assays with focus/stress fiber phenotypes","pmids":["11438522","11336706"],"confidence":"High","gaps":["How actin association feeds back on GEF output not defined","Endogenous regulators analogous to kaposin A not identified"]},{"year":2001,"claim":"Separated PH-dependent firm arrest from GEF- and integrin-binding-dependent migration under flow and named ARF6 as the chemotaxis-relevant target.","evidence":"PH, GEF-dead, and β2-binding mutants in flow-based leukocyte adhesion and transendothelial migration assays with ARF6 dominant-negative rescue","pmids":["11747824"],"confidence":"Medium","gaps":["Single-lab dissection without genetic knockout","How PH domain mediates arrest independently of GEF activity unresolved"]},{"year":2002,"claim":"Identified Cybr as a coiled-coil partner that enhances cytohesin-1 GEF activity, adding a protein cofactor layer to ARF activation.","evidence":"Co-IP of overexpressed proteins and in vitro ARF exchange assays with recombinant Cybr","pmids":["11867758"],"confidence":"Medium","gaps":["Co-IP from overexpression without endogenous validation","Cellular consequence of Cybr-cytohesin coupling not defined"]},{"year":2003,"claim":"Linked LFA-1 signaling through cytohesin-1 to ERK activation, JAB-1 release, and Th1 differentiation, connecting adhesion machinery to downstream immune transcriptional outcomes.","evidence":"Phosphoprotein flow cytometry and dominant-negative cytohesin-1 with cytokine production assays","pmids":["14528303"],"confidence":"Medium","gaps":["Dominant-negative approach without knockout","Direct versus indirect role in JAB-1 release not separated"]},{"year":2005,"claim":"Extended cytohesin-1 function to innate immune phagocytosis by showing it is required for CD14-regulated, CR3-mediated mycobacterial internalization.","evidence":"siRNA knockdown, PI3K inhibitors, and Co-IP of CR3 with cytohesin-1, plus flow cytometry phagocytosis assays","pmids":["15778383"],"confidence":"Medium","gaps":["Single-lab knockdown without rescue","Whether GEF activity is required for phagocytosis not tested"]},{"year":2009,"claim":"Established a specific cytohesin-1/Arf6 axis driving neutrophil effector functions, linking the GEF to PLD, NADPH oxidase, and degranulation.","evidence":"SecinH3 inhibition, siRNA, and stable overexpression in PLB-985 cells with Arf6/Arf1 activation, PLD, superoxide, and granule marker assays","pmids":["20018626"],"confidence":"High","gaps":["Spatial coupling of Arf6 to NADPH oxidase not resolved","In vivo neutrophil relevance not tested"]},{"year":2012,"claim":"Defined Fyn phosphorylation at Tyr-382 as an in vivo regulatory switch required for peripheral myelination, providing genetic causality in a tissue context.","evidence":"In vitro Fyn kinase assay plus Schwann cell-specific Y382F transgenic and cytohesin-1 knockout mice with peripheral nerve electron microscopy","pmids":["23012656"],"confidence":"High","gaps":["How Y382 phosphorylation alters GEF activity mechanistically unclear","Upstream signal activating Fyn in Schwann cells not defined"]},{"year":2013,"claim":"Showed the cytohesin-1/Arf6 axis and Y382 are required for Schwann cell migration and that gain-of-function enhances myelination in vivo, consolidating the myelination mechanism.","evidence":"siRNA, SecinH3, knockout, and Y382F rescue in transwell migration assays; Schwann cell-specific transgenic overexpression with nerve morphometry and Arf6 activation assays","pmids":["23517829","23636892"],"confidence":"Medium","gaps":["Effectors downstream of Arf6 in migration/myelination not identified","Single-lab in vivo gain-of-function"]},{"year":2016,"claim":"Demonstrated CYTH1 controls hematopoietic stem/progenitor cell adhesion and bone marrow homing, integrating integrin β1 activation with in vivo niche lodgment.","evidence":"RNAi screen and shRNA knockdown with adhesion assays, integrin β1 activation assay, xenograft transplantation, and intravital microscopy","pmids":["27899358"],"confidence":"High","gaps":["Whether GEF activity versus integrin binding drives homing not separated","ARF target in HSPCs not identified"]},{"year":2018,"claim":"Revealed that a microexon-encoded PH domain difference toggles PI(3,4,5)P3 versus PI(4,5)P2 selectivity to spatially route Arf6 signaling during RTK-driven migration.","evidence":"Microexon splicing analysis, phosphoinositide binding assays, live-cell imaging of GFP isoforms, and HGF/Met migration assays with isoform-specific knockdown and rescue","pmids":["30404949"],"confidence":"High","gaps":["Regulation of microexon inclusion across tissues not defined","Whether other CYTH paralogs share this switch not addressed"]},{"year":2023,"claim":"Implicated CYTH1 in leukemic cell adhesion, homing, engraftment, and survival, nominating it as a therapeutic target whose inhibition lowers ITGB2 and MCL1.","evidence":"shRNA knockdown and SecinH3 inhibition in AML cell lines and xenografts with proliferation, apoptosis, and Western blot readouts, plus venetoclax synergy","pmids":["37644132"],"confidence":"Medium","gaps":["Mechanism linking CYTH1 to MCL1 regulation unresolved","Single-lab pharmacology without genetic patient validation"]},{"year":null,"claim":"How phosphorylation states, lipid selectivity, and accessory partners are integrated to select between specific ARF substrates and downstream effectors in a given cellular context remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified structural model coupling PH-domain lipid sensing to Sec7 substrate selection","Endogenous effectors downstream of Arf1 versus Arf6 in distinct cell types not fully mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[1,4,5,9]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,5,9]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[3,6,24]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,9]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2,6,24]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[12]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[6]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[13]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,2,9]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[8,18,19,23]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[1,12,19]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[20,22,24]}],"complexes":[],"partners":["ITGB2","ARF1","ARF6","ARD1","PSCDBP","PRKCD","FYN","ITGAM"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q15438","full_name":"Cytohesin-1","aliases":["PH, SEC7 and coiled-coil domain-containing protein 1","SEC7 homolog B2-1"],"length_aa":398,"mass_kda":46.4,"function":"Promotes guanine-nucleotide exchange on ARF1, ARF5 and ARF6. 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inhibits T cell receptor-stimulated adhesion.\",\n      \"method\": \"Co-interaction assay with integrin β2 cytoplasmic domain; overexpression and dominant-negative studies in Jurkat cells measuring ICAM-1 adhesion\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal functional analysis with multiple constructs (full-length, SEC7 domain, PH domain) across multiple groups, seminal paper replicated by many subsequent studies\",\n      \"pmids\": [\"8706128\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Cytohesin-1 functions as a guanine nucleotide-exchange protein (GEP) for ARF GTPases, accelerating GDP-to-GTP exchange on ARF1 and ARF3 purified from bovine brain; this GEP activity is not inhibited by brefeldin A, distinguishing it from BFA-sensitive ARF-GEPs.\",\n      \"method\": \"In vitro GEP assay with recombinant cytohesin-1 (expressed in E. coli) and purified ARF; [35S]GTPγS binding and [3H]GDP release assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro reconstitution assay with purified proteins, replicated by multiple subsequent biochemical studies\",\n      \"pmids\": [\"9050849\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Constitutively active PI 3-kinase is sufficient to activate Jurkat cell adhesion to ICAM-1 and induces membrane recruitment of cytohesin-1; this effect requires the cytohesin-1 PH domain, placing PI 3-kinase upstream of cytohesin-1 in the β2 integrin inside-out signaling pathway.\",\n      \"method\": \"Overexpression of constitutively active PI 3-kinase; dominant-negative PH domain constructs; membrane fractionation to assess cytohesin-1 localization; adhesion assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — epistasis established by gain-of-function and dominant-negative approaches with defined cellular readout; replicated across multiple labs\",\n      \"pmids\": [\"9614087\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Both the PH domain and the adjacent C-terminal polybasic (c) domain of cytohesin-1 are required together for high-affinity (100 nM) binding to PI(3,4,5)P3 and for plasma membrane association and biological function; the isolated PH domain has substantially lower affinity (~2–3 µM) for PI(3,4,5)P3.\",\n      \"method\": \"Biosensor affinity measurements; deletion/chimeric mutant expression in Jurkat cells; membrane association assays; functional adhesion assays\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro binding quantified by biosensor combined with mutational analysis and functional cellular assays in a single study\",\n      \"pmids\": [\"9693361\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"NMR solution structure of the cytohesin-1 Sec7 domain reveals 10 α-helices forming a unique fold; ARF1 binding occurs through a large surface on the C-terminal subdomain involving hydrophobic and polar residues; structure-based mutagenesis identified residues critical for ARF binding and nucleotide exchange. However, the Sec7 domain and the β2 integrin cytoplasmic domain do not interact in solution phase.\",\n      \"method\": \"NMR spectroscopy; 1H-15N and 1H-13C chemical shift perturbation mapping; structure-based mutagenesis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — NMR structure with functional mutagenesis validation in a single rigorous study\",\n      \"pmids\": [\"9653114\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The cytohesin-1 Sec7 domain catalyzes guanine nucleotide exchange on ARFs 1, 5, and 6, yeast ARFs 1–3, and ARD1; full-length cytohesin-1 shows narrower substrate specificity (active on ARF1, ARF3, and ARD1 but not ARF5/6), indicating that regions outside the Sec7 domain contribute to substrate specificity. Neither acts on ARF-like (ARL) proteins.\",\n      \"method\": \"In vitro GTPγS binding assays with purified recombinant proteins; comparison of Sec7 domain alone vs. full-length cytohesin-1 across a panel of ARF/ARL substrates\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic in vitro reconstitution across multiple substrates with purified proteins\",\n      \"pmids\": [\"9756891\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Cytohesin-1 PH domain binds the inositol head group of PI(3,4,5)P3 (as IP4) with >200-fold higher affinity than PI(4,5)P2 or PI(3,4)P2 in vitro; EGF- or NGF-stimulated translocation of GFP-cytohesin-1 from cytosol to plasma membrane in PC12 cells requires PI 3-kinase activity and an intact PH domain.\",\n      \"method\": \"In vitro PH domain-lipid binding assays; GFP-cytohesin-1 live-cell confocal microscopy in PC12 cells; wortmannin/LY294002 inhibition; dominant-negative p85 co-expression\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro binding with quantitative affinity measurement combined with live-cell imaging and PI3K inhibitor/dominant-negative validation\",\n      \"pmids\": [\"10341214\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Structural elements in ARF1 required for functional interaction with cytohesin-1 include the N-terminal α-helix (residues 1–13), switch 1 region (residues 28–50, including Lys-38), and C-terminal region (last 42 amino acids); replacing Lys-38 with Gln abolishes the interaction with both cytohesin-1 and its Sec7 domain.\",\n      \"method\": \"ARF1/ARL1 chimeric protein panel; site-directed mutagenesis; in vitro [35S]GTPγS binding assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic in vitro mutagenesis and chimera analysis with reconstituted exchange activity\",\n      \"pmids\": [\"10212218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Cytohesin-1 is required for LPS-induced β2 integrin (LFA-1)-mediated monocyte adherence to ICAM-1 downstream of CD14, Rho, and PI 3-kinase; antisense knockdown of cytohesin-1 abrogates LPS-induced adherence without affecting LFA-1 surface expression.\",\n      \"method\": \"Cytohesin-1 antisense oligonucleotides in THP-1/CD14 cells; PI 3-kinase inhibitors; Toxin B (Rho inhibitor); ICAM-1 adhesion assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — antisense knockdown with functional adhesion readout and pathway inhibitors; single lab but multiple pathway perturbations\",\n      \"pmids\": [\"9873050\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Cytohesin-1 regulates β2 integrin adhesion through two separable mechanisms: (1) direct interaction with the LFA-1 β2 cytoplasmic domain activates an extracellular epitope of LFA-1 independent of ARF-GEF activity; (2) ARF-GEF activity is required for LFA-1-mediated cell spreading on ICAM-1. A GEF-dead mutant of cytohesin-1 blocks spreading but not initial LFA-1 activation.\",\n      \"method\": \"Mutational analysis of β2 cytoplasmic domain; cytohesin-1 GEF-dead mutant (E157K); in vitro ARF GDP-GTP exchange assays; LFA-1 activation epitope detection; cell adhesion and spreading assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — combined in vitro GEF assay with mutagenesis and multiple cellular functional readouts dissecting two distinct mechanisms\",\n      \"pmids\": [\"10835351\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"PI(3,4,5)P3 differentially regulates cytohesin-1 GEF specificity: it suppresses cytohesin-1-dependent GTP binding to ARF6-Ig chimeras while enhancing GTP binding to ARF1-Ig chimeras, thereby switching ARF substrate specificity of cytohesin-1.\",\n      \"method\": \"In vitro GTP-binding assays using immunoprecipitated ARF1-Ig and ARF6-Ig chimeras from mammalian cells; addition of purified phosphoinositides\",\n      \"journal\": \"European journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro functional assay with defined lipid additions, single lab, single method\",\n      \"pmids\": [\"10848997\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Cytohesin-1 specifically accelerates GTPγS binding to ARD1 (a 64-kDa lysosomal/Golgi GTPase) but not cytohesin-2; the specificity is determined by residue 30 in the Sec7 domain and the ARD1 effector region; in COS-7 cells, overexpressed ARD1 and cytohesin-1 partially colocalize.\",\n      \"method\": \"Yeast two-hybrid screen (ARD1 as bait); in vitro [35S]GTPγS binding assays; Sec7 domain point mutagenesis; confocal fluorescence microscopy of co-transfected COS-7 cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — yeast two-hybrid plus in vitro GEF assay plus mutagenesis plus colocalization; single lab\",\n      \"pmids\": [\"10748148\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"B2-1/cytohesin-1 localizes to the Golgi complex (not primarily the plasma membrane) under endogenous expression conditions; this Golgi association is disrupted by brefeldin A; overexpression of GFP-B2-1 shows Golgi targeting and excessive overexpression causes partial Golgi dispersion.\",\n      \"method\": \"Immunofluorescence localization; brefeldin A treatment; transient transfection of GFP-tagged B2-1; confocal microscopy\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct localization by imaging with BFA perturbation; single lab, single approach\",\n      \"pmids\": [\"10772823\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Protein kinase Cδ phosphorylates a serine/threonine motif within the C-terminal polybasic domain of cytohesin-1 in vitro; phorbol ester stimulation also induces phosphorylation of these residues in vivo; PKC-phosphorylated cytohesin-1 associates tightly with the actin cytoskeleton and phosphorylation is required for maximal LFA-1-mediated Jurkat cell adhesion to ICAM-1.\",\n      \"method\": \"In vitro kinase assay with purified PKCδ; phorbol ester stimulation in vivo; co-sedimentation with actin cytoskeleton; site-directed mutagenesis; adhesion assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro kinase assay plus in vivo phosphorylation confirmed plus cytoskeletal fractionation plus functional adhesion readout with mutagenesis\",\n      \"pmids\": [\"11438522\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Human herpesvirus 8 kaposin A directly interacts with cytohesin-1 and recruits it to the membrane; this interaction mediates kaposin A-induced focus formation, stress fiber dissolution, and ERK-1/2 MAP kinase activation; these effects are reversed by the GEF-dead cytohesin-1 E157K mutant; liposome-embedded kaposin A specifically stimulates cytohesin-1-dependent GTP binding to myristoylated ARF1 in vitro.\",\n      \"method\": \"Co-immunoprecipitation; dominant-negative GEF mutant (E157K) rescue; in vitro ARF GTP-binding assay with liposome-embedded kaposin A; focus formation and stress fiber assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro reconstitution combined with Co-IP, mutagenesis rescue, and multiple cellular phenotype readouts\",\n      \"pmids\": [\"11336706\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Cytohesin-1 overexpression increases LFA-1-dependent leukocyte arrest triggered by chemokines on cytokine-activated endothelium; the PH domain (not GEF activity) mediates firm arrest, while both LFA-1 interaction and GEF activity are required for shape change and transendothelial chemotaxis; ARF6 (but not ARF1) participates as downstream GEF target in chemotaxis.\",\n      \"method\": \"Overexpression and dominant-negative constructs (PH domain, GEF-dead mutant, β2 cytoplasmic domain mutant) in flow-based leukocyte adhesion assays on endothelium; transendothelial migration assays; ARF6 dominant-negative rescue\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple dominant-negative constructs dissecting pathway, physiologically relevant flow assay; single lab\",\n      \"pmids\": [\"11747824\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Cybr (a cytokine-inducible protein related to GRASP) physically interacts with cytohesin-1 via coiled-coil domain interactions and enhances cytohesin-1-catalyzed GTPγS binding to ARF in vitro.\",\n      \"method\": \"Co-immunoprecipitation of overexpressed proteins from 293T cells; in vitro ARF GEP activity assay with recombinant Cybr\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus in vitro GEF activity assay; single lab, two orthogonal methods\",\n      \"pmids\": [\"11867758\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"LFA-1 activation induces phosphorylation of the β2 integrin chain, releases JAB-1, and mediates ERK1/2 signaling through cytohesin-1; dominant-negative cytohesin-1 inhibits IL-2 production and impairs Th1 differentiation.\",\n      \"method\": \"Intracellular phosphoprotein staining with 13-dimensional flow cytometry; dominant-negative cytohesin-1 expression; cytokine production assays\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — phosphoprotein flow cytometry combined with dominant-negative functional readouts; single lab, multiple orthogonal assays\",\n      \"pmids\": [\"14528303\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"CD14-regulated complement receptor 3 (CR3/Mac-1)-dependent phagocytosis of mycobacteria requires cytohesin-1; cytohesin-1 physically associates with CR3 upon stimulation with mycobacterial surface components; knockdown of cytohesin-1 specifically abrogates CD14-regulated CR3-mediated BCG internalization.\",\n      \"method\": \"siRNA knockdown of cytohesin-1; PI3K inhibitors; blocking antibodies; flow cytometry phagocytosis assay; co-immunoprecipitation of CR3 and cytohesin-1\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with specific phagocytosis readout plus physical association by Co-IP; single lab\",\n      \"pmids\": [\"15778383\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Cytohesin-1 specifically activates Arf6 (but not Arf1) in fMLP-stimulated human neutrophils; cytohesin-1/Arf6 signaling drives phospholipase D activation, NADPH oxidase-dependent superoxide production, and degranulation; SecinH3 (selective cytohesin Sec7 inhibitor) blocks these responses, as does cytohesin-1 siRNA knockdown.\",\n      \"method\": \"SecinH3 pharmacological inhibition; siRNA knockdown; stable overexpression in PLB-985 cells; Arf6 and Arf1 activation assays; PLD activity assay; superoxide production assay; surface granule marker expression by flow cytometry\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological inhibition, siRNA, and stable overexpression all converge on same phenotype with multiple functional readouts; single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"20018626\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The Src-family kinase Fyn phosphorylates cytohesin-1 at tyrosine 382 (Y382); this phosphorylation is required for full myelination by Schwann cells. Transgenic mice expressing a Schwann cell-specific Y382F phosphorylation-deficient cytohesin-1 show delayed myelination and reduced myelin thickness similar to cytohesin-1 knockout mice.\",\n      \"method\": \"In vitro kinase assay (Fyn + cytohesin-1); phosphorylation-deficient transgenic mice (Y382F, Schwann cell-specific); cytohesin-1 knockout mice; electron microscopy of peripheral nerves\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro kinase assay with mutagenesis plus in vivo genetic rescue in two independent mouse models converging on same phenotype\",\n      \"pmids\": [\"23012656\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Cytohesin-1 and its downstream GTPase Arf6 are required for peripheral neuronal conditioned medium-stimulated migration of primary Schwann cells; the Y382 residue (Fyn phosphorylation site) is required for migration since Y382F cytohesin-1 fails to rescue migration in siRNA-transfected cells.\",\n      \"method\": \"siRNA knockdown of cytohesin-1 and Arf6; SecinH3 inhibitor; cytohesin-1 knockout Schwann cells; reintroduction of siRNA-resistant wild-type vs. Y382F cytohesin-1; transwell migration assay\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA + inhibitor + KO + rescue with mutant; single lab, multiple convergent approaches\",\n      \"pmids\": [\"23517829\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Schwann cell-specific overexpression of wild-type cytohesin-1 in transgenic mice produces enhanced myelin thickness in peripheral nerves and elevated downstream Arf6 activation, confirming cytohesin-1 promotes myelination in vivo through the cytohesin-1/Arf6 signaling axis.\",\n      \"method\": \"Schwann cell-specific transgenic overexpression of cytohesin-1; electron microscopy morphometry of peripheral nerves; Arf6 activation assay\",\n      \"journal\": \"Journal of molecular neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo transgenic gain-of-function with morphometric and biochemical readouts; single lab\",\n      \"pmids\": [\"23636892\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CYTH1 knockdown disrupts adhesion of human cord blood hematopoietic stem and progenitor cells (HSPCs) to mesenchymal stroma cells, fibronectin, and ICAM-1/2, reduces integrin β1 activation, impairs bone marrow homing after transplantation into immunodeficient mice, and impairs HSPC lodgment in the marrow niche as shown by intravital microscopy.\",\n      \"method\": \"RNAi screen; shRNA knockdown; adhesion assays; integrin β1 activation assay; xenograft transplantation; intravital microscopy\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA/shRNA with multiple orthogonal readouts (adhesion assays, in vivo engraftment, intravital microscopy); single lab but comprehensive mechanistic analysis\",\n      \"pmids\": [\"27899358\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"A microexon-encoded triglycine vs. diglycine difference in the cytohesin-1 PH domain determines differential phosphoinositide affinity (triglycine for PI(4,5)P2, diglycine for PI(3,4,5)P3); this distinction produces distinct subcellular localizations (triglycine to plasma membrane, diglycine to leading edge) and controls Met RTK-dependent cell migration, where the diglycine/PI(3,4,5)P3-binding isoform is specifically required.\",\n      \"method\": \"Alternative splicing microexon analysis; phosphoinositide binding assays; live-cell imaging of GFP-tagged isoforms; HGF/Met-stimulated migration assays; isoform-specific knockdown and rescue\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro lipid binding combined with live-cell imaging, isoform-specific knockdown and rescue with defined localization and functional readouts\",\n      \"pmids\": [\"30404949\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CYTH1 depletion or inhibition with SecinH3 inhibits adhesion, migration, homing, and engraftment of AML leukemic cells in vivo; targeting CYTH1 suppresses integrin-associated adhesion signaling by reducing ITGB2 expression and reduces anti-apoptotic MCL1; SecinH3 synergizes with BCL2-inhibitor venetoclax in ABT-199-resistant AML cells.\",\n      \"method\": \"CYTH1 shRNA knockdown; SecinH3 pharmacological inhibition; AML cell line proliferation and apoptosis assays; AML xenograft mouse model; Western blotting for signaling components\",\n      \"journal\": \"Acta pharmacologica Sinica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — shRNA and pharmacological inhibition in vitro and in vivo with multiple functional and molecular readouts; single lab\",\n      \"pmids\": [\"37644132\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"Cytohesin-1 is a Sec7-domain-containing guanine nucleotide exchange factor (GEF) for ARF GTPases (primarily ARF1 and ARF6) that is recruited to the plasma membrane via cooperative high-affinity PI(3,4,5)P3 binding by its PH domain and C-terminal polybasic domain downstream of PI 3-kinase; it directly engages the β2 integrin cytoplasmic domain to activate LFA-1-mediated cell adhesion through two separable mechanisms—integrin conformational activation (GEF-independent) and ARF-GEF-dependent cytoskeletal remodeling and cell spreading—and is regulated by PKCδ phosphorylation (promoting actin cytoskeleton association) and Fyn-mediated phosphorylation at Y382 (required for Schwann cell myelination and migration via Arf6 activation); a microexon-encoded PH domain isoform further tunes PI(3,4,5)P3 versus PI(4,5)P2 selectivity to spatially restrict Arf6 signaling during RTK-driven cell migration.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"Cytohesin-1 (CYTH1) is a Sec7-domain guanine nucleotide exchange factor (GEF) for ARF GTPases that couples phosphoinositide 3-kinase signaling to integrin-mediated cell adhesion, cytoskeletal remodeling, and cell migration [#1, #2, #9]. It accelerates GDP-to-GTP exchange on ARF1, ARF3, and ARF6 in a brefeldin A-insensitive manner, with the isolated Sec7 domain acting on a broader ARF panel than the full-length protein, indicating that flanking regions tune substrate specificity [#1, #5]; the Sec7 fold engages ARF1 through its C-terminal subdomain, and exchange requires the ARF1 N-terminal helix, switch 1 (Lys-38), and C-terminus [#4, #7]. Membrane recruitment downstream of PI 3-kinase depends on cooperative high-affinity PI(3,4,5)P3 binding by the PH domain together with the adjacent C-terminal polybasic domain [#2, #3, #6]. Cytohesin-1 directly binds the integrin \\u03b22 (CD18) cytoplasmic domain and activates LFA-1-mediated adhesion through two separable mechanisms: a GEF-independent conformational activation of LFA-1 and a GEF-dependent program of cell spreading [#0, #9]. Through these activities it drives leukocyte arrest and transendothelial migration, monocyte and HSPC adhesion and homing, CR3-dependent phagocytosis, and neutrophil ARF6-driven PLD activation, superoxide production, and degranulation [#15, #23, #18, #19]. Its activity is regulated by PKC\\u03b4 phosphorylation of the polybasic domain, which promotes actin cytoskeleton association, and by Fyn-mediated phosphorylation at Tyr-382, which is required for Schwann cell myelination and migration via Arf6 [#13, #20, #21]. A microexon-encoded PH domain variation switches PI(3,4,5)P3 versus PI(4,5)P2 selectivity to spatially restrict Arf6 signaling during RTK-driven migration [#24]. CYTH1 also supports leukemic cell adhesion, homing, and survival, where its inhibition reduces ITGB2 and MCL1 [#25].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Established cytohesin-1 as a physical and functional link between an integrin cytoplasmic tail and inside-out adhesion signaling, answering how LFA-1 adhesiveness might be controlled intracellularly.\",\n      \"evidence\": \"Integrin \\u03b22 cytoplasmic domain interaction assays and overexpression/dominant-negative constructs in Jurkat cells with ICAM-1 adhesion readout\",\n      \"pmids\": [\"8706128\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the biochemical activity of the SEC7 domain\", \"Mechanism of how PH domain inhibits adhesion unresolved\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Defined the molecular activity of cytohesin-1 as a brefeldin A-insensitive ARF-GEF, identifying the enzymatic basis for its downstream effects.\",\n      \"evidence\": \"In vitro [35S]GTP\\u03b3S binding and [3H]GDP release assays with recombinant cytohesin-1 and purified ARF1/ARF3\",\n      \"pmids\": [\"9050849\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not connect GEF activity to adhesion phenotype\", \"ARF6 not yet tested\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Placed PI 3-kinase upstream of cytohesin-1 and defined the lipid-binding module governing membrane recruitment, establishing the signaling logic of the pathway.\",\n      \"evidence\": \"Constitutively active PI3K and dominant-negative PH constructs with membrane fractionation and adhesion assays; biosensor affinity measurements of PH plus polybasic domain binding to PI(3,4,5)P3\",\n      \"pmids\": [\"9614087\", \"9693361\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo PI(3,4,5)P3 dynamics not visualized at this stage\", \"Whether membrane recruitment alone suffices for activation unresolved\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Resolved the Sec7 domain structure and ARF substrate range, distinguishing intrinsic catalytic specificity from full-length regulation and showing the Sec7 domain does not bind the integrin tail directly.\",\n      \"evidence\": \"NMR solution structure with chemical shift perturbation mapping and structure-based mutagenesis; in vitro GTP\\u03b3S assays across an ARF/ARL panel comparing Sec7 domain to full-length protein\",\n      \"pmids\": [\"9653114\", \"9756891\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the integrin-binding interface not identified\", \"Determinants outside Sec7 that narrow specificity not mapped\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Confirmed PI(3,4,5)P3-selective PH binding drives PI3K-dependent membrane translocation in response to RTK stimulation and mapped the ARF1 surfaces required for productive exchange.\",\n      \"evidence\": \"In vitro PH-lipid affinity assays and GFP-cytohesin-1 imaging in EGF/NGF-stimulated PC12 cells with PI3K inhibitors; ARF1/ARL1 chimera and Lys-38 mutagenesis with in vitro exchange assays\",\n      \"pmids\": [\"10341214\", \"10212218\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address ARF6-specific recruitment\", \"Effector consequences downstream of activated ARF not defined\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Demonstrated a physiological requirement for cytohesin-1 in LPS-induced, PI3K- and Rho-dependent monocyte adhesion, extending its role beyond T cells.\",\n      \"evidence\": \"Antisense knockdown in THP-1/CD14 cells with Rho and PI3K inhibitors and ICAM-1 adhesion assays\",\n      \"pmids\": [\"9873050\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single antisense approach without genetic rescue\", \"Direct molecular link to CD14 not established\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Dissected adhesion into a GEF-independent LFA-1 conformational activation step and a GEF-dependent spreading step, clarifying how one protein controls two adhesion outputs.\",\n      \"evidence\": \"\\u03b22 tail mutants and GEF-dead E157K cytohesin-1 with in vitro exchange assays, activation-epitope detection, and adhesion/spreading assays\",\n      \"pmids\": [\"10835351\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the spreading-relevant ARF in vivo not pinned down\", \"How direct binding triggers conformational change mechanistically unclear\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Showed phosphoinositides and accessory targets modulate cytohesin-1 ARF preference, adding regulatory and substrate complexity to the GEF.\",\n      \"evidence\": \"In vitro GTP-binding assays with ARF1-Ig/ARF6-Ig chimeras and added phosphoinositides; yeast two-hybrid, in vitro exchange, Sec7 mutagenesis, and COS-7 colocalization with ARD1; Golgi localization by immunofluorescence with BFA\",\n      \"pmids\": [\"10848997\", \"10748148\", \"10772823\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Lipid-driven specificity switch shown only in vitro with chimeric substrates\", \"Endogenous Golgi versus plasma membrane balance not reconciled across cell types\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identified post-translational and pathogen-driven regulation: PKC\\u03b4 phosphorylation links cytohesin-1 to the actin cytoskeleton, and kaposin A hijacks its GEF activity to remodel cells.\",\n      \"evidence\": \"In vitro PKC\\u03b4 kinase assay with in vivo phorbol ester phosphorylation, actin co-sedimentation, and adhesion assays; Co-IP, E157K rescue, and liposome-embedded kaposin A in vitro ARF assays with focus/stress fiber phenotypes\",\n      \"pmids\": [\"11438522\", \"11336706\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How actin association feeds back on GEF output not defined\", \"Endogenous regulators analogous to kaposin A not identified\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Separated PH-dependent firm arrest from GEF- and integrin-binding-dependent migration under flow and named ARF6 as the chemotaxis-relevant target.\",\n      \"evidence\": \"PH, GEF-dead, and \\u03b22-binding mutants in flow-based leukocyte adhesion and transendothelial migration assays with ARF6 dominant-negative rescue\",\n      \"pmids\": [\"11747824\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab dissection without genetic knockout\", \"How PH domain mediates arrest independently of GEF activity unresolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identified Cybr as a coiled-coil partner that enhances cytohesin-1 GEF activity, adding a protein cofactor layer to ARF activation.\",\n      \"evidence\": \"Co-IP of overexpressed proteins and in vitro ARF exchange assays with recombinant Cybr\",\n      \"pmids\": [\"11867758\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Co-IP from overexpression without endogenous validation\", \"Cellular consequence of Cybr-cytohesin coupling not defined\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Linked LFA-1 signaling through cytohesin-1 to ERK activation, JAB-1 release, and Th1 differentiation, connecting adhesion machinery to downstream immune transcriptional outcomes.\",\n      \"evidence\": \"Phosphoprotein flow cytometry and dominant-negative cytohesin-1 with cytokine production assays\",\n      \"pmids\": [\"14528303\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Dominant-negative approach without knockout\", \"Direct versus indirect role in JAB-1 release not separated\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Extended cytohesin-1 function to innate immune phagocytosis by showing it is required for CD14-regulated, CR3-mediated mycobacterial internalization.\",\n      \"evidence\": \"siRNA knockdown, PI3K inhibitors, and Co-IP of CR3 with cytohesin-1, plus flow cytometry phagocytosis assays\",\n      \"pmids\": [\"15778383\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab knockdown without rescue\", \"Whether GEF activity is required for phagocytosis not tested\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Established a specific cytohesin-1/Arf6 axis driving neutrophil effector functions, linking the GEF to PLD, NADPH oxidase, and degranulation.\",\n      \"evidence\": \"SecinH3 inhibition, siRNA, and stable overexpression in PLB-985 cells with Arf6/Arf1 activation, PLD, superoxide, and granule marker assays\",\n      \"pmids\": [\"20018626\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Spatial coupling of Arf6 to NADPH oxidase not resolved\", \"In vivo neutrophil relevance not tested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defined Fyn phosphorylation at Tyr-382 as an in vivo regulatory switch required for peripheral myelination, providing genetic causality in a tissue context.\",\n      \"evidence\": \"In vitro Fyn kinase assay plus Schwann cell-specific Y382F transgenic and cytohesin-1 knockout mice with peripheral nerve electron microscopy\",\n      \"pmids\": [\"23012656\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How Y382 phosphorylation alters GEF activity mechanistically unclear\", \"Upstream signal activating Fyn in Schwann cells not defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed the cytohesin-1/Arf6 axis and Y382 are required for Schwann cell migration and that gain-of-function enhances myelination in vivo, consolidating the myelination mechanism.\",\n      \"evidence\": \"siRNA, SecinH3, knockout, and Y382F rescue in transwell migration assays; Schwann cell-specific transgenic overexpression with nerve morphometry and Arf6 activation assays\",\n      \"pmids\": [\"23517829\", \"23636892\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Effectors downstream of Arf6 in migration/myelination not identified\", \"Single-lab in vivo gain-of-function\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstrated CYTH1 controls hematopoietic stem/progenitor cell adhesion and bone marrow homing, integrating integrin \\u03b21 activation with in vivo niche lodgment.\",\n      \"evidence\": \"RNAi screen and shRNA knockdown with adhesion assays, integrin \\u03b21 activation assay, xenograft transplantation, and intravital microscopy\",\n      \"pmids\": [\"27899358\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether GEF activity versus integrin binding drives homing not separated\", \"ARF target in HSPCs not identified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Revealed that a microexon-encoded PH domain difference toggles PI(3,4,5)P3 versus PI(4,5)P2 selectivity to spatially route Arf6 signaling during RTK-driven migration.\",\n      \"evidence\": \"Microexon splicing analysis, phosphoinositide binding assays, live-cell imaging of GFP isoforms, and HGF/Met migration assays with isoform-specific knockdown and rescue\",\n      \"pmids\": [\"30404949\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Regulation of microexon inclusion across tissues not defined\", \"Whether other CYTH paralogs share this switch not addressed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Implicated CYTH1 in leukemic cell adhesion, homing, engraftment, and survival, nominating it as a therapeutic target whose inhibition lowers ITGB2 and MCL1.\",\n      \"evidence\": \"shRNA knockdown and SecinH3 inhibition in AML cell lines and xenografts with proliferation, apoptosis, and Western blot readouts, plus venetoclax synergy\",\n      \"pmids\": [\"37644132\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking CYTH1 to MCL1 regulation unresolved\", \"Single-lab pharmacology without genetic patient validation\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How phosphorylation states, lipid selectivity, and accessory partners are integrated to select between specific ARF substrates and downstream effectors in a given cellular context remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified structural model coupling PH-domain lipid sensing to Sec7 substrate selection\", \"Endogenous effectors downstream of Arf1 versus Arf6 in distinct cell types not fully mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [1, 4, 5, 9]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 5, 9]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [3, 6, 24]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 9]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2, 6, 24]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [12]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 2, 9]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [8, 18, 19, 23]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [1, 12, 19]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [20, 22, 24]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"ITGB2\",\n      \"ARF1\",\n      \"ARF6\",\n      \"ARD1\",\n      \"PSCDBP\",\n      \"PRKCD\",\n      \"FYN\",\n      \"ITGAM\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":8,"faith_pct":87.5}}