{"gene":"PACSIN2","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":2011,"finding":"PACSIN2 F-BAR domain directly interacts with caveolin-1, sculpts caveolar plasma membrane invaginations, and recruits dynamin-2 for caveola fission; knockdown of PACSIN2 causes abnormal caveolin-1-associated plasma membrane morphology and decreased dynamin-2 recruitment.","method":"Direct binding assay (F-BAR domain–caveolin-1 interaction), membrane tubulation assay, siRNA knockdown with morphological readout","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assays, membrane tubulation reconstitution, and KD phenotype in a focused single-gene study replicated by multiple subsequent papers","pmids":["21610094"],"is_preprint":false},{"year":2011,"finding":"PACSIN2 associates with the C-terminal hypervariable domain of Rac1 at intracellular tubular structures and early endosomes; loss of PACSIN2 increases Rac1-GTP levels and promotes cell spreading and migration, while ectopic PACSIN2 reduces Rac1-GTP in a manner dependent on the PACSIN2–Rac1 interaction, PACSIN2 membrane-tubulating capacity, and dynamin.","method":"Co-immunoprecipitation, siRNA knockdown, wound-healing migration assay, Rac1-GTP pull-down, live-cell imaging","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, functional rescue experiments, multiple orthogonal readouts in single lab","pmids":["21693584"],"is_preprint":false},{"year":2000,"finding":"Xenopus PACSIN2 (X-PACSIN2) binds the cytoplasmic domain of ADAM13 via SH3-domain interactions in vitro and colocalizes with ADAM13 in membrane ruffles and cytoplasmic vesicles; PACSIN2 overexpression rescues ADAM13-induced developmental defects, while the truncated ΔSH3 form increases ADAM13 activity, indicating PACSIN2 negatively regulates ADAM13 function via its SH3 domain.","method":"Pull-down assay, co-localization in XTC cells, developmental rescue experiment, truncation mutant analysis","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pull-down plus functional in vivo rescue with domain mutant, single lab","pmids":["11076687"],"is_preprint":false},{"year":2014,"finding":"The PACSIN2 F-BAR domain directly binds actin filaments using the same concave surface employed for membrane binding; this interaction is specific to pacsin2 among tested BAR/F-BAR proteins (endophilin, CIP4, FCHO2 did not associate with actin).","method":"In vitro actin co-sedimentation, structural analysis (cryo-EM/crystallography implied), mutagenesis of membrane-binding surface","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstituted binding assay with mutagenesis and structural context, single lab but multiple orthogonal methods","pmids":["25216944"],"is_preprint":false},{"year":2015,"finding":"Filamin A (FlnA) binds the tip of the PACSIN2 F-BAR domain (requiring FlnA immunoglobulin-like repeat 20) and enhances PACSIN2 F-BAR domain membrane tubulation in vitro; the FlnA–PACSIN2 interaction regulates PACSIN2 localization and demarcation membrane system (DMS) formation in megakaryocytes, and Flna-null platelets show dispersed PACSIN2 foci and poorly defined DMS.","method":"Co-immunoprecipitation in human platelets, in vitro membrane tubulation assay, Flna-null mouse model, fluorescence microscopy","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, in vitro tubulation, KO mouse model with defined morphological phenotype, single lab","pmids":["25838348"],"is_preprint":false},{"year":2015,"finding":"Protein kinase C (PKC) phosphorylates PACSIN2 at serine 313, reducing its membrane-binding and tubulation capacities; phosphorylation decreases caveolar tracking duration at the plasma membrane and correlates with increased dynamin-2 recruitment and activity, triggering caveolae removal. EHD2 expression restores caveolar stability in PACSIN2-depleted or phospho-mimetic S313E cells.","method":"Site-directed mutagenesis (S313E phospho-mimetic), live-cell caveolar tracking, PKC pharmacological activation, RNAi depletion, in vitro membrane binding assay","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis, in vitro biochemistry, live-cell imaging with quantitative phenotype, multiple orthogonal methods in one study","pmids":["26092940"],"is_preprint":false},{"year":2016,"finding":"PACSIN2 concentrates at focal adherens junctions (FAJs) experiencing actomyosin tension, recruited via its F-BAR domain to the trailing end of fast-moving FAJs; PACSIN2 inhibits internalization of VE-cadherin from FAJ trailing ends, and loss of PACSIN2 impairs endothelial monolayer integrity.","method":"siRNA knockdown, photoconversion and FRAP microscopy, super-resolution microscopy, live-cell imaging, F-BAR domain mutant analysis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple imaging modalities, domain mutant, KD with defined functional phenotype, single lab","pmids":["27417273"],"is_preprint":false},{"year":2016,"finding":"TcdA (C. difficile toxin A) undergoes PACSIN2-dependent, dynamin-dependent but clathrin- and caveolae-independent endocytosis; TcdA colocalizes with PACSIN2-positive structures during entry, and RNAi knockdown of PACSIN2 inhibits TcdA uptake and downstream cytopathic effects.","method":"RNAi knockdown, pharmacological inhibition, confocal microscopy with fluorescently labeled toxin","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNAi KD with functional and imaging readouts, multiple inhibitor approaches, single lab","pmids":["27942025"],"is_preprint":false},{"year":2018,"finding":"HIV-1 p6 recruits PACSIN2 into virus-like particles independently of TSG101/ALIX; HIV-1 spreading in T cells and PBMCs is severely impaired upon PACSIN2 depletion and can be restored by wild-type PACSIN2 but not by an SH3-domain mutant unable to interact with WASP/N-WASP, indicating PACSIN2 promotes HIV-1 cell-to-cell spread by connecting Gag to the actin cytoskeleton via its SH3 domain.","method":"VLP incorporation assay, siRNA knockdown, spreading assay, SH3 domain mutant rescue experiment","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Moderate — VLP recruitment assay, KD, domain-mutant rescue with clear mechanistic interpretation, single lab but multiple orthogonal methods","pmids":["29891700"],"is_preprint":false},{"year":2019,"finding":"PACSIN2 localizes to L. monocytogenes protrusions and promotes protrusion engulfment during bacterial cell-to-cell spread; RNAi knockdown of PACSIN2 reduces spread efficiency.","method":"RNAi screen, fluorescence microscopy, bacterial spread assay","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — focused functional KD with imaging, single lab, single method per finding","pmids":["31242077"],"is_preprint":false},{"year":2019,"finding":"PACSIN2 promotes apical endocytosis in intestinal epithelial cells; PACSIN2 KO mice show reduced microvillar numbers and membrane-lifting defects at brush borders, with loss of dynamin-2 from microvillar rootlets; inhibition of endocytosis phenocopies PACSIN2 loss, placing PACSIN2-dependent endocytic scission upstream of microvillar membrane morphology maintenance.","method":"PACSIN2 KO mouse, electron microscopy, live-cell endocytosis assay, dynamin2 localization by immunofluorescence","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — KO mouse with ultrastructural phenotype, epistasis via endocytosis inhibition, multiple orthogonal readouts, single lab","pmids":["31390291"],"is_preprint":false},{"year":2020,"finding":"PACSIN2 interacts with HCV NS5A via the NS5A domain I and the PACSIN2 F-BAR region; NS5A prevents PKCα from binding PACSIN2, reducing phosphorylation of PACSIN2 at S313 and enhancing NS5A–PACSIN2 interaction; PACSIN2 is required for HCV assembly (not entry or replication) and promotes NS5A–core protein interaction and lipid droplet formation via ERK1/2.","method":"Co-immunoprecipitation, pulldown assay, immunofluorescence, siRNA knockdown, S313A mutagenesis, viral infectivity assay","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, domain mapping, mutagenesis, KD with viral assembly phenotype, multiple orthogonal methods in single lab","pmids":["31801866"],"is_preprint":false},{"year":2021,"finding":"PACSIN2 recruits trafficking regulators EHD4 and MICAL-L1 to the rear end of asymmetric adherens junctions to form a recycling endosome-like tubular structure; this PACSIN2/EHD4/MICAL-L1 complex controls local VE-cadherin trafficking and coordinates polarized endothelial migration and angiogenic sprouting.","method":"Co-immunoprecipitation, live-cell imaging, siRNA knockdown, in vivo zebrafish angiogenesis assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — complex formation by Co-IP, functional KD, in vivo validation, multiple orthogonal methods, single lab","pmids":["33972531"],"is_preprint":false},{"year":2017,"finding":"PACSIN2 colocalizes and physically interacts with nephrin in podocytes; PACSIN2 overexpression increases both nephrin endocytosis and recycling; rabenosyn-5 is identified as a novel PACSIN2 interactor that enhances the PACSIN2–nephrin association; palmitate (elevated in diabetes) further enhances this association.","method":"Co-immunoprecipitation, co-localization microscopy, overexpression endocytosis assay, pull-down","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, functional overexpression assay with trafficking readout, multiple interaction partners identified, single lab","pmids":["28550045"],"is_preprint":false},{"year":2012,"finding":"PACSIN2 loss increases plasma membrane expression of EGFR in resting cells and enhances EGF-induced EGFR phosphorylation, Erk and Akt activation, and cell proliferation; internalized EGF and activated EGFR translocate to PACSIN2-positive endosomes, identifying PACSIN2 as a regulator of EGFR surface levels and downstream signaling.","method":"siRNA knockdown, surface EGFR quantification, phospho-immunoblotting, proliferation assay, confocal co-localization","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD with multiple downstream signaling readouts and imaging, single lab","pmids":["23129763"],"is_preprint":false},{"year":2008,"finding":"Xenopus PACSIN2 localizes to the plasma membrane via its coiled-coil domain; overexpression inhibits gastrulation, fibronectin fibrillogenesis, and ectodermal cell spreading on fibronectin; PACSIN2 overexpression prevents integrin β1 localization to focal adhesions and filamin localization to stress fibers in XTC cells, indicating PACSIN2 regulates activated α5β1 integrin and cytoskeletal organization during cell migration.","method":"Overexpression and truncation mutant analysis in Xenopus embryos, immunofluorescence, cell spreading assay on fibronectin, mitochondria-anchoring sequestration experiment","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — domain mutant analysis, multiple orthogonal readouts, in vivo and cell culture validation, single lab","pmids":["18495106"],"is_preprint":false},{"year":2022,"finding":"PACSIN2 acts as a scaffold in CML cells: it binds Cobll1 and separately binds and inhibits SH3BP1 (a Rac1 pathway activator); Cobll1 preferentially competes with SH3BP1 for PACSIN2 binding, releasing SH3BP1 to activate Rac1 signaling and suppress TKI-induced apoptosis, leading to drug resistance.","method":"Co-immunoprecipitation, competitive binding assay, siRNA knockdown, apoptosis assay in K562 cells","journal":"Cancer medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, competitive binding with affinity measurement, functional KD, single lab","pmids":["35352878"],"is_preprint":false},{"year":2022,"finding":"Super-resolution microscopy shows that PACSIN2 and EHD2 both localize at caveolin-1-positive caveolae, with PACSIN2 F-BAR domain positioned closer to the plasma membrane than EHD2 and caveolin-1, suggesting PACSIN2 connects caveolae to the plasma membrane; PACSIN2 and EHD2 are present predominantly at typically sized (full-volume) caveolae.","method":"Single-molecule localization super-resolution (3D-STORM/PALM), spatial proximity clustering analysis","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — high-resolution structural localization with quantitative analysis, single lab, no functional perturbation","pmids":["35834519"],"is_preprint":false},{"year":2023,"finding":"PACSIN2 inhibits autophagy, putatively by interacting with LC3-II via a LIR motif to inhibit autophagosome formation; knockdown of PACSIN2 modulates mercaptopurine-induced cytotoxicity in intestinal cells; PACSIN2 modulates cellular TPMT activity via mechanisms distinct from its autophagy regulation.","method":"siRNA knockdown, autophagy flux assay, co-immunoprecipitation (PACSIN2–LC3-II), LIR motif analysis, cytotoxicity assay","journal":"Life science alliance","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with LC3-II, KD functional assay, domain motif analysis; single lab but multiple complementary approaches","pmids":["36596605"],"is_preprint":false},{"year":2023,"finding":"PACSIN2 phosphorylation at S313 is increased in diabetic kidney disease glomeruli; pS313-PACSIN2 decreases N-WASP degradation; N-WASP inhibition reciprocally triggers PACSIN2 S313 phosphorylation; pS313-PACSIN2 regulates actin cytoskeleton rearrangement in podocytes, and the dynamic phosphorylation cycle is required for podocyte morphology maintenance.","method":"Phospho-specific antibody staining in rat DKD glomeruli, pharmacological N-WASP inhibition, phospho-mimetic and phospho-dead PACSIN2 mutants, actin cytoskeleton imaging","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo disease model, mutagenesis, pharmacological epistasis, single lab","pmids":["37296607"],"is_preprint":false},{"year":2023,"finding":"PACSIN2 negatively regulates platelet integrin β1 hemostatic function through its interaction with filamin A; Pacsin2-/- mice display thrombocytopenia, prolonged bleeding, unstable thrombi, and hyperactive integrin β1; genetic deletion of integrin β1 in Pacsin2-/- mice normalizes platelet count, hemostasis, and thrombus formation, placing PACSIN2 upstream of integrin β1 activation.","method":"Pacsin2 KO mouse, integrin β1 KO epistasis, ferric chloride and laser injury thrombosis models, spreading assay on GFOGER, active integrin β1 antibody (9EG7) staining, FlnA-binding peptide pull-down","journal":"Journal of thrombosis and haemostasis","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO mouse with multiple functional readouts, genetic epistasis rescue, biochemical pull-down, single lab but highly rigorous multi-method design","pmids":["37678551"],"is_preprint":false},{"year":2022,"finding":"In zebrafish larvae, pacsin2 is enriched at the apical pole of renal proximal tubule cells at endocytic structures; loss of pacsin2 reduces endocytosis in the proximal tubule and decreases abundance of megalin and endocytic organelles.","method":"Pacsin2 morpholino knockdown in zebrafish, fluorescence microscopy, endocytosis assay, megalin immunostaining","journal":"Biology open","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — in vivo KD with localization and functional endocytosis readout, single lab, zebrafish model","pmids":["35616009"],"is_preprint":false},{"year":2026,"finding":"In hippocampal CA1 neurons, chronic stress upregulates PACSIN2; PACSIN2 physically interacts with dynamin and cooperatively modulates postsynaptic GluA1 AMPA receptor expression; selective knockdown of PACSIN2 in dCA1 enhances synaptic transmission and ameliorates depression-like behaviors in rats.","method":"Co-immunoprecipitation (PACSIN2–dynamin), viral-vector-mediated knockdown in dCA1, electrophysiology, behavioral assays","journal":"Acta pharmacologica Sinica","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP, region-specific KD with electrophysiology and behavioral readouts, single lab","pmids":["42098399"],"is_preprint":false},{"year":2012,"finding":"PACSIN2 knockdown in human leukemia cells (NALM6) results in significantly lower TPMT activity, and a PACSIN2 SNP (rs2413739) is associated with altered TPMT activity in patients; protein-level correlation between PACSIN2 and TPMT was detected in PBMCs.","method":"siRNA knockdown with TPMT activity assay, genome-wide association in HapMap cell lines, patient cohort validation","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-based KD with enzymatic activity readout plus independent human cohort replication, but mechanism of PACSIN2–TPMT regulation not molecularly characterized","pmids":["22846425"],"is_preprint":false}],"current_model":"PACSIN2 is an F-BAR domain membrane-sculpting protein that shapes caveolae by directly binding caveolin-1 and recruiting dynamin-2 for fission, with PKC-mediated phosphorylation at S313 acting as a molecular switch that reduces membrane binding and triggers caveolae removal; beyond caveolae, PACSIN2 regulates clathrin-independent endocytosis, VE-cadherin and nephrin trafficking, EGFR surface levels, integrin β1 activation (via filamin A), Rac1 signaling, actin cytoskeleton organization (via N-WASP and WASP/N-WASP SH3-domain interactions), autophagy (via LC3-II interaction), and serves as a proviral factor exploited by HIV-1, HCV, C. difficile TcdA, and L. monocytogenes."},"narrative":{"mechanistic_narrative":"PACSIN2 is an F-BAR domain membrane-sculpting protein that couples plasma membrane remodeling to dynamin-dependent membrane scission and to the actin cytoskeleton across endocytic and cell-junction contexts [PMID:21610094, PMID:25216944]. At caveolae, its F-BAR domain directly binds caveolin-1, sculpts caveolar invaginations, and recruits dynamin-2 for fission [PMID:21610094]; super-resolution imaging places the PACSIN2 F-BAR closer to the plasma membrane than EHD2 and caveolin-1, positioning it as the link between caveolae and the membrane [PMID:35834519]. PKC phosphorylation at serine 313 acts as a switch that reduces PACSIN2 membrane binding and tubulation, shortening caveolar lifetime and triggering dynamin-2-driven caveolae removal, with EHD2 restoring caveolar stability [PMID:26092940]. Distinctively among BAR/F-BAR proteins, the PACSIN2 F-BAR binds actin filaments through the same concave surface used for membrane binding [PMID:25216944], and Filamin A binds the F-BAR tip to enhance tubulation and direct PACSIN2 localization [PMID:25838348]. Through these activities PACSIN2 drives clathrin-independent and apical endocytosis and regulates surface trafficking of multiple cargoes: it restrains VE-cadherin internalization at tension-bearing adherens junctions by organizing an EHD4/MICAL-L1 recycling-endosome-like tubular structure to coordinate polarized endothelial migration and angiogenic sprouting [PMID:27417273, PMID:33972531], controls nephrin endocytosis and recycling in podocytes [PMID:28550045], limits surface EGFR and downstream Erk/Akt signaling [PMID:23129763], and maintains brush-border microvillar morphology via dynamin-2-dependent apical endocytic scission [PMID:31390291]. PACSIN2 negatively regulates Rac1 activity through its membrane-tubulating and dynamin-dependent functions and a Rac1 hypervariable-domain interaction [PMID:21693584], and acts as a scaffold balancing Cobll1 and SH3BP1 to tune Rac1 signaling [PMID:35352878]. It negatively regulates integrin β1 activation via Filamin A, with Pacsin2 deletion causing thrombocytopenia and unstable thrombi that are normalized by integrin β1 deletion [PMID:37678551]. PACSIN2 also serves as a host factor exploited by pathogens, promoting HIV-1 cell-to-cell spread by linking Gag to actin through its SH3-domain interaction with WASP/N-WASP [PMID:29891700], supporting HCV assembly via NS5A binding [PMID:31801866], and mediating entry of C. difficile TcdA and spread of L. monocytogenes [PMID:27942025, PMID:31242077].","teleology":[{"year":2000,"claim":"Established the earliest functional readout for PACSIN2 as an SH3-domain adaptor that negatively regulates a transmembrane partner during development.","evidence":"Pull-down, colocalization, and developmental rescue with ΔSH3 mutant of Xenopus PACSIN2 against ADAM13","pmids":["11076687"],"confidence":"Medium","gaps":["Performed on Xenopus ortholog only","Did not address membrane-sculpting or endocytic roles"]},{"year":2008,"claim":"Linked PACSIN2 to integrin β1 and cytoskeletal organization during cell migration, foreshadowing its later integrin-regulatory role.","evidence":"Overexpression and truncation analysis in Xenopus embryos and XTC cells with fibronectin spreading assays","pmids":["18495106"],"confidence":"Medium","gaps":["Largely overexpression-based","Molecular basis of integrin regulation not defined here"]},{"year":2011,"claim":"Defined the core mechanism: the F-BAR domain directly binds caveolin-1, sculpts caveolae, and recruits dynamin-2 for fission, establishing PACSIN2 as a caveolar membrane-sculpting protein.","evidence":"Direct F-BAR–caveolin-1 binding, membrane tubulation assay, and siRNA knockdown with morphological readout","pmids":["21610094"],"confidence":"High","gaps":["Did not establish regulatory switch controlling fission timing","In vitro tubulation versus physiological caveolar dynamics"]},{"year":2011,"claim":"Showed PACSIN2 negatively regulates Rac1 activity through its membrane-tubulating and dynamin-dependent functions, connecting it to migration control.","evidence":"Co-IP, Rac1-GTP pull-down, wound-healing migration assay, and live imaging with interaction- and tubulation-dependent rescue","pmids":["21693584"],"confidence":"High","gaps":["Direct versus endosome-mediated regulation of Rac1 not fully resolved","GEF/GAP intermediary not identified in this study"]},{"year":2014,"claim":"Revealed that the F-BAR domain binds actin filaments via the same concave surface used for membranes, a property unique to PACSIN2 among tested F-BAR proteins, coupling membrane and cytoskeletal functions.","evidence":"In vitro actin co-sedimentation with mutagenesis of the membrane-binding surface and structural context","pmids":["25216944"],"confidence":"High","gaps":["Competition between membrane and actin binding in cells not quantified","Physiological consequence of dual binding not directly tested"]},{"year":2015,"claim":"Identified Filamin A as an F-BAR tip-binding partner that enhances tubulation and directs PACSIN2 localization, controlling demarcation membrane formation in megakaryocytes.","evidence":"Reciprocal Co-IP in platelets, in vitro tubulation, and Flna-null mouse morphology","pmids":["25838348"],"confidence":"High","gaps":["Did not connect FlnA interaction to integrin function directly","Mechanism of tubulation enhancement not structurally resolved"]},{"year":2015,"claim":"Established PKC phosphorylation of S313 as the molecular switch that reduces membrane binding and triggers dynamin-2-dependent caveolae removal, explaining how caveolar lifetime is regulated.","evidence":"S313E phospho-mimetic mutagenesis, live-cell caveolar tracking, PKC activation, and EHD2 rescue","pmids":["26092940"],"confidence":"High","gaps":["In vivo PKC isoform specificity at S313 not fully defined here","Crosstalk with actin binding not addressed"]},{"year":2016,"claim":"Showed PACSIN2 is recruited by tension to trailing adherens junctions and inhibits VE-cadherin internalization, defining a role in endothelial barrier integrity.","evidence":"siRNA knockdown, photoconversion/FRAP, super-resolution and live-cell imaging, F-BAR mutant analysis","pmids":["27417273"],"confidence":"High","gaps":["Tension-sensing mechanism of recruitment not molecularly defined","Trafficking machinery downstream identified only later"]},{"year":2016,"claim":"Demonstrated PACSIN2 mediates a clathrin- and caveolae-independent but dynamin-dependent endocytic route, exploited by C. difficile toxin A.","evidence":"RNAi knockdown, pharmacological inhibition, and confocal imaging of labeled TcdA","pmids":["27942025"],"confidence":"Medium","gaps":["Direct toxin–PACSIN2 interaction not shown","Cargo selectivity of this pathway unresolved"]},{"year":2017,"claim":"Extended cargo regulation to nephrin trafficking in podocytes and identified rabenosyn-5 as a partner enhancing the association, with disease-relevant palmitate modulation.","evidence":"Co-IP, colocalization, overexpression endocytosis/recycling assay, and pull-down","pmids":["28550045"],"confidence":"Medium","gaps":["Relies on overexpression for trafficking readout","Endogenous physiological balance of endocytosis versus recycling unclear"]},{"year":2018,"claim":"Defined a proviral role where PACSIN2 connects HIV-1 Gag to the actin cytoskeleton via its SH3 domain to promote cell-to-cell spread.","evidence":"VLP incorporation, siRNA knockdown, spreading assay, and SH3-mutant rescue in T cells and PBMCs","pmids":["29891700"],"confidence":"High","gaps":["Structural detail of Gag–SH3 interaction not resolved","Whether membrane sculpting contributes alongside SH3 not separated"]},{"year":2019,"claim":"Showed PACSIN2-dependent endocytic scission maintains apical microvillar membrane morphology, and supports L. monocytogenes protrusion engulfment.","evidence":"PACSIN2 KO mouse ultrastructure with dynamin-2 mislocalization, and RNAi bacterial spread assay","pmids":["31390291","31242077"],"confidence":"High","gaps":["Cargo whose endocytosis maintains microvilli not identified","Listeria engulfment mechanism only correlative"]},{"year":2020,"claim":"Revealed HCV exploitation: NS5A binds the F-BAR region and blocks PKCα-mediated S313 phosphorylation, linking the phospho-switch to viral assembly.","evidence":"Co-IP, domain mapping, S313A mutagenesis, knockdown, and infectivity assays","pmids":["31801866"],"confidence":"High","gaps":["How reduced phosphorylation mechanistically aids assembly not fully defined","Role of lipid-droplet ERK1/2 axis only partially mapped"]},{"year":2021,"claim":"Identified the PACSIN2/EHD4/MICAL-L1 tubular recycling complex that controls local VE-cadherin trafficking and polarized endothelial migration and sprouting.","evidence":"Co-IP, live imaging, siRNA knockdown, and in vivo zebrafish angiogenesis","pmids":["33972531"],"confidence":"High","gaps":["Assembly hierarchy of the complex not fully ordered","Direct versus indirect EHD4/MICAL-L1 binding not separated"]},{"year":2022,"claim":"Refined the spatial model of caveolae by placing PACSIN2 F-BAR closest to the membrane and identified a Cobll1/SH3BP1 scaffold switch tuning Rac1-dependent drug resistance.","evidence":"Single-molecule super-resolution clustering analysis; competitive Co-IP and apoptosis assays in K562 cells; zebrafish proximal tubule endocytosis","pmids":["35834519","35352878","35616009"],"confidence":"Medium","gaps":["Super-resolution lacked functional perturbation","Scaffold competition affinities measured in single system"]},{"year":2023,"claim":"Established disease-context roles: S313 phosphorylation regulates podocyte actin via N-WASP, and PACSIN2 restrains platelet integrin β1 via Filamin A in hemostasis.","evidence":"Phospho-specific staining in DKD glomeruli with phospho-mutants; Pacsin2 KO and integrin β1 KO epistasis with thrombosis models and FlnA pull-down","pmids":["37296607","37678551"],"confidence":"High","gaps":["Kinase/phosphatase cycle governing S313 in vivo not fully mapped","How FlnA binding suppresses integrin activation mechanistically unresolved"]},{"year":2023,"claim":"Implicated PACSIN2 in autophagy inhibition via a putative LIR-LC3-II interaction and in modulation of thiopurine drug response.","evidence":"siRNA knockdown, autophagy flux, LC3-II Co-IP, LIR analysis, and cytotoxicity assays","pmids":["36596605"],"confidence":"Medium","gaps":["LIR-mediated LC3-II binding described as putative","Mechanism linking PACSIN2 to TPMT activity not molecularly defined"]},{"year":2026,"claim":"Extended PACSIN2 function to neurons, where it cooperates with dynamin to control GluA1 AMPA receptor expression and influences stress-related behavior.","evidence":"Co-IP, region-specific knockdown in dCA1, electrophysiology, and behavioral assays in rats","pmids":["42098399"],"confidence":"Medium","gaps":["Whether GluA1 regulation reflects endocytic scission not directly shown","Single model system"]},{"year":null,"claim":"How PACSIN2's dual membrane- and actin-binding F-BAR surface is dynamically partitioned and regulated in vivo, and how a single scission machinery is selectively deployed across caveolae, junctions, podocytes, microvilli, and neurons, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified structural model integrating membrane, actin, and phospho-switch states","Cargo-selection logic across tissues undefined","Endogenous kinase/phosphatase control of S313 in each context unmapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[0,5]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[3]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[12,16]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,20]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,17,6]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[1,12,14]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[2,7]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[3,15]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[7,12,13]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,14,16]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[8,11,7]},{"term_id":"R-HSA-109582","term_label":"Hemostasis","supporting_discovery_ids":[20]}],"complexes":["PACSIN2/EHD4/MICAL-L1 tubular recycling complex"],"partners":["CAV1","DNM2","FLNA","RAC1","WASL","EHD2","MICALL1","NPHS1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UNF0","full_name":"Protein kinase C and casein kinase substrate in neurons protein 2","aliases":["Syndapin-2","Syndapin-II","SdpII"],"length_aa":486,"mass_kda":55.7,"function":"Regulates the morphogenesis and endocytosis of caveolae (By similarity). Lipid-binding protein that is able to promote the tubulation of the phosphatidic acid-containing membranes it preferentially binds. Plays a role in intracellular vesicle-mediated transport. Involved in the endocytosis of cell-surface receptors like the EGF receptor, contributing to its internalization in the absence of EGF stimulus (PubMed:21693584, PubMed:23129763, PubMed:23236520, PubMed:23596323). Essential for endothelial organization in sprouting angiogenesis, modulates CDH5-based junctions. Facilitates endothelial front-rear polarity during migration by recruiting EHD4 and MICALL1 to asymmetric adherens junctions between leader and follower cells (By similarity) (Microbial infection) Specifically enhances the efficiency of HIV-1 virion spread by cell-to-cell transfer (PubMed:29891700). Also promotes the protrusion engulfment during cell-to-cell spread of bacterial pathogens like Listeria monocytogenes (PubMed:31242077). Involved in lipid droplet formation, which is important for HCV virion assembly (PubMed:31801866)","subcellular_location":"Cytoplasm; Cytoplasm, cytoskeleton; Cytoplasmic vesicle membrane; Cell projection, ruffle membrane; Early endosome; Recycling endosome membrane; Cell membrane; Cell projection; Membrane, caveola; Cell junction, adherens junction","url":"https://www.uniprot.org/uniprotkb/Q9UNF0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PACSIN2","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000100266","cell_line_id":"CID000540","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"membrane","grade":2}],"interactors":[{"gene":"RHOQ","stoichiometry":10.0},{"gene":"ACTG1","stoichiometry":0.2},{"gene":"CLEC16A","stoichiometry":0.2},{"gene":"MICALL1","stoichiometry":0.2},{"gene":"RAI14","stoichiometry":0.2},{"gene":"PACSIN3","stoichiometry":0.2},{"gene":"HELZ2","stoichiometry":0.2},{"gene":"TRIOBP","stoichiometry":0.2},{"gene":"COBLL1","stoichiometry":0.2},{"gene":"MPRIP","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000540","total_profiled":1310},"omim":[{"mim_id":"606513","title":"PROTEIN KINASE C AND CASEIN KINASE SUBSTRATE IN NEURONS 3; PACSIN3","url":"https://www.omim.org/entry/606513"},{"mim_id":"606512","title":"PROTEIN KINASE C AND CASEIN KINASE SUBSTRATE IN NEURONS 1; PACSIN1","url":"https://www.omim.org/entry/606512"},{"mim_id":"604960","title":"PROTEIN KINASE C AND CASEIN KINASE SUBSTRATE IN NEURONS 2; PACSIN2","url":"https://www.omim.org/entry/604960"},{"mim_id":"601047","title":"CAVEOLIN 1; CAV1","url":"https://www.omim.org/entry/601047"},{"mim_id":"143100","title":"HUNTINGTON DISEASE; HD","url":"https://www.omim.org/entry/143100"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nuclear speckles","reliability":"Approved"},{"location":"Plasma membrane","reliability":"Approved"},{"location":"Vesicles","reliability":"Additional"},{"location":"Primary cilium","reliability":"Additional"},{"location":"Centriolar satellite","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PACSIN2"},"hgnc":{"alias_symbol":["SDPII"],"prev_symbol":[]},"alphafold":{"accession":"Q9UNF0","domains":[{"cath_id":"2.30.30.40","chopping":"430-485","consensus_level":"high","plddt":92.9584,"start":430,"end":485},{"cath_id":"1.10.287","chopping":"130-227","consensus_level":"medium","plddt":96.3519,"start":130,"end":227}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UNF0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UNF0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UNF0-F1-predicted_aligned_error_v6.png","plddt_mean":81.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PACSIN2","jax_strain_url":"https://www.jax.org/strain/search?query=PACSIN2"},"sequence":{"accession":"Q9UNF0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UNF0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UNF0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UNF0"}},"corpus_meta":[{"pmid":"21610094","id":"PMC_21610094","title":"Essential role of PACSIN2/syndapin-II in caveolae membrane sculpting.","date":"2011","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/21610094","citation_count":120,"is_preprint":false},{"pmid":"21693584","id":"PMC_21693584","title":"The F-BAR domain protein PACSIN2 associates with Rac1 and regulates cell spreading and migration.","date":"2011","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/21693584","citation_count":76,"is_preprint":false},{"pmid":"22846425","id":"PMC_22846425","title":"PACSIN2 polymorphism influences TPMT activity and mercaptopurine-related gastrointestinal toxicity.","date":"2012","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22846425","citation_count":61,"is_preprint":false},{"pmid":"11076687","id":"PMC_11076687","title":"PACSIN2 is a regulator of the metalloprotease/disintegrin ADAM13.","date":"2000","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/11076687","citation_count":58,"is_preprint":false},{"pmid":"25216944","id":"PMC_25216944","title":"Direct interaction of actin filaments with F-BAR protein pacsin2.","date":"2014","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/25216944","citation_count":50,"is_preprint":false},{"pmid":"25838348","id":"PMC_25838348","title":"FlnA binding to PACSIN2 F-BAR domain regulates membrane tubulation in megakaryocytes and platelets.","date":"2015","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/25838348","citation_count":49,"is_preprint":false},{"pmid":"26092940","id":"PMC_26092940","title":"Phosphorylation of PACSIN2 by protein kinase C triggers the removal of caveolae from the plasma membrane.","date":"2015","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/26092940","citation_count":41,"is_preprint":false},{"pmid":"27417273","id":"PMC_27417273","title":"The F-BAR protein pacsin2 inhibits asymmetric VE-cadherin internalization from tensile adherens junctions.","date":"2016","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/27417273","citation_count":40,"is_preprint":false},{"pmid":"27942025","id":"PMC_27942025","title":"Clostridium difficile Toxin A Undergoes Clathrin-Independent, PACSIN2-Dependent Endocytosis.","date":"2016","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/27942025","citation_count":35,"is_preprint":false},{"pmid":"33972531","id":"PMC_33972531","title":"A junctional PACSIN2/EHD4/MICAL-L1 complex coordinates VE-cadherin trafficking for endothelial migration and angiogenesis.","date":"2021","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/33972531","citation_count":34,"is_preprint":false},{"pmid":"28550045","id":"PMC_28550045","title":"PACSIN2 accelerates nephrin trafficking and is up-regulated in diabetic kidney disease.","date":"2017","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/28550045","citation_count":32,"is_preprint":false},{"pmid":"23129763","id":"PMC_23129763","title":"The F-BAR protein PACSIN2 regulates epidermal growth factor receptor internalization.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23129763","citation_count":29,"is_preprint":false},{"pmid":"31242077","id":"PMC_31242077","title":"RNAi screen reveals a role for PACSIN2 and caveolins during bacterial cell-to-cell spread.","date":"2019","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/31242077","citation_count":22,"is_preprint":false},{"pmid":"27452984","id":"PMC_27452984","title":"PACSIN2 polymorphism is associated with thiopurine-induced hematological toxicity in children with acute lymphoblastic leukaemia undergoing maintenance therapy.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/27452984","citation_count":22,"is_preprint":false},{"pmid":"31792371","id":"PMC_31792371","title":"PACSIN2 rs2413739 influence on thiopurine pharmacokinetics: validation studies in pediatric patients.","date":"2019","source":"The pharmacogenomics journal","url":"https://pubmed.ncbi.nlm.nih.gov/31792371","citation_count":21,"is_preprint":false},{"pmid":"29891700","id":"PMC_29891700","title":"HIV-1 gag recruits PACSIN2 to promote virus spreading.","date":"2018","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/29891700","citation_count":20,"is_preprint":false},{"pmid":"31390291","id":"PMC_31390291","title":"PACSIN2-dependent apical endocytosis regulates the morphology of epithelial microvilli.","date":"2019","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/31390291","citation_count":17,"is_preprint":false},{"pmid":"18495106","id":"PMC_18495106","title":"PACSIN2 regulates cell adhesion during gastrulation in Xenopus laevis.","date":"2008","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/18495106","citation_count":16,"is_preprint":false},{"pmid":"26745030","id":"PMC_26745030","title":"Possible regulation of caveolar endocytosis and flattening by phosphorylation of F-BAR domain protein PACSIN2/Syndapin II.","date":"2015","source":"Bioarchitecture","url":"https://pubmed.ncbi.nlm.nih.gov/26745030","citation_count":15,"is_preprint":false},{"pmid":"31801866","id":"PMC_31801866","title":"PACSIN2 Interacts with Nonstructural Protein 5A and Regulates Hepatitis C Virus Assembly.","date":"2020","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/31801866","citation_count":10,"is_preprint":false},{"pmid":"36596605","id":"PMC_36596605","title":"PACSIN2 as a modulator of autophagy and mercaptopurine cytotoxicity: mechanisms in lymphoid and intestinal cells.","date":"2023","source":"Life science alliance","url":"https://pubmed.ncbi.nlm.nih.gov/36596605","citation_count":7,"is_preprint":false},{"pmid":"35352878","id":"PMC_35352878","title":"Reciprocal interactions among Cobll1, PACSIN2, and SH3BP1 regulate drug resistance in chronic myeloid leukemia.","date":"2022","source":"Cancer medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35352878","citation_count":7,"is_preprint":false},{"pmid":"35834519","id":"PMC_35834519","title":"Super-resolution analysis of PACSIN2 and EHD2 at caveolae.","date":"2022","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/35834519","citation_count":6,"is_preprint":false},{"pmid":"35616009","id":"PMC_35616009","title":"Pacsin2 is required for endocytosis in the zebrafish pronephric tubule.","date":"2022","source":"Biology open","url":"https://pubmed.ncbi.nlm.nih.gov/35616009","citation_count":2,"is_preprint":false},{"pmid":"37296607","id":"PMC_37296607","title":"Phosphorylation of PACSIN2 at S313 Regulates Podocyte Architecture in Coordination with N-WASP.","date":"2023","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/37296607","citation_count":1,"is_preprint":false},{"pmid":"37678551","id":"PMC_37678551","title":"PACSIN2 regulates platelet integrin β1 hemostatic function.","date":"2023","source":"Journal of thrombosis and haemostasis : JTH","url":"https://pubmed.ncbi.nlm.nih.gov/37678551","citation_count":1,"is_preprint":false},{"pmid":"42098399","id":"PMC_42098399","title":"PACSIN2-mediated synaptic injury contributes to behavioral disorders caused by chronic stress.","date":"2026","source":"Acta pharmacologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/42098399","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15080,"output_tokens":6005,"usd":0.067657,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14801,"output_tokens":5740,"usd":0.108753,"stage2_stop_reason":"end_turn"},"total_usd":0.17641,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"PACSIN2 F-BAR domain directly interacts with caveolin-1, sculpts caveolar plasma membrane invaginations, and recruits dynamin-2 for caveola fission; knockdown of PACSIN2 causes abnormal caveolin-1-associated plasma membrane morphology and decreased dynamin-2 recruitment.\",\n      \"method\": \"Direct binding assay (F-BAR domain–caveolin-1 interaction), membrane tubulation assay, siRNA knockdown with morphological readout\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assays, membrane tubulation reconstitution, and KD phenotype in a focused single-gene study replicated by multiple subsequent papers\",\n      \"pmids\": [\"21610094\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PACSIN2 associates with the C-terminal hypervariable domain of Rac1 at intracellular tubular structures and early endosomes; loss of PACSIN2 increases Rac1-GTP levels and promotes cell spreading and migration, while ectopic PACSIN2 reduces Rac1-GTP in a manner dependent on the PACSIN2–Rac1 interaction, PACSIN2 membrane-tubulating capacity, and dynamin.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, wound-healing migration assay, Rac1-GTP pull-down, live-cell imaging\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, functional rescue experiments, multiple orthogonal readouts in single lab\",\n      \"pmids\": [\"21693584\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Xenopus PACSIN2 (X-PACSIN2) binds the cytoplasmic domain of ADAM13 via SH3-domain interactions in vitro and colocalizes with ADAM13 in membrane ruffles and cytoplasmic vesicles; PACSIN2 overexpression rescues ADAM13-induced developmental defects, while the truncated ΔSH3 form increases ADAM13 activity, indicating PACSIN2 negatively regulates ADAM13 function via its SH3 domain.\",\n      \"method\": \"Pull-down assay, co-localization in XTC cells, developmental rescue experiment, truncation mutant analysis\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pull-down plus functional in vivo rescue with domain mutant, single lab\",\n      \"pmids\": [\"11076687\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The PACSIN2 F-BAR domain directly binds actin filaments using the same concave surface employed for membrane binding; this interaction is specific to pacsin2 among tested BAR/F-BAR proteins (endophilin, CIP4, FCHO2 did not associate with actin).\",\n      \"method\": \"In vitro actin co-sedimentation, structural analysis (cryo-EM/crystallography implied), mutagenesis of membrane-binding surface\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstituted binding assay with mutagenesis and structural context, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"25216944\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Filamin A (FlnA) binds the tip of the PACSIN2 F-BAR domain (requiring FlnA immunoglobulin-like repeat 20) and enhances PACSIN2 F-BAR domain membrane tubulation in vitro; the FlnA–PACSIN2 interaction regulates PACSIN2 localization and demarcation membrane system (DMS) formation in megakaryocytes, and Flna-null platelets show dispersed PACSIN2 foci and poorly defined DMS.\",\n      \"method\": \"Co-immunoprecipitation in human platelets, in vitro membrane tubulation assay, Flna-null mouse model, fluorescence microscopy\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, in vitro tubulation, KO mouse model with defined morphological phenotype, single lab\",\n      \"pmids\": [\"25838348\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Protein kinase C (PKC) phosphorylates PACSIN2 at serine 313, reducing its membrane-binding and tubulation capacities; phosphorylation decreases caveolar tracking duration at the plasma membrane and correlates with increased dynamin-2 recruitment and activity, triggering caveolae removal. EHD2 expression restores caveolar stability in PACSIN2-depleted or phospho-mimetic S313E cells.\",\n      \"method\": \"Site-directed mutagenesis (S313E phospho-mimetic), live-cell caveolar tracking, PKC pharmacological activation, RNAi depletion, in vitro membrane binding assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis, in vitro biochemistry, live-cell imaging with quantitative phenotype, multiple orthogonal methods in one study\",\n      \"pmids\": [\"26092940\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"PACSIN2 concentrates at focal adherens junctions (FAJs) experiencing actomyosin tension, recruited via its F-BAR domain to the trailing end of fast-moving FAJs; PACSIN2 inhibits internalization of VE-cadherin from FAJ trailing ends, and loss of PACSIN2 impairs endothelial monolayer integrity.\",\n      \"method\": \"siRNA knockdown, photoconversion and FRAP microscopy, super-resolution microscopy, live-cell imaging, F-BAR domain mutant analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple imaging modalities, domain mutant, KD with defined functional phenotype, single lab\",\n      \"pmids\": [\"27417273\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"TcdA (C. difficile toxin A) undergoes PACSIN2-dependent, dynamin-dependent but clathrin- and caveolae-independent endocytosis; TcdA colocalizes with PACSIN2-positive structures during entry, and RNAi knockdown of PACSIN2 inhibits TcdA uptake and downstream cytopathic effects.\",\n      \"method\": \"RNAi knockdown, pharmacological inhibition, confocal microscopy with fluorescently labeled toxin\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNAi KD with functional and imaging readouts, multiple inhibitor approaches, single lab\",\n      \"pmids\": [\"27942025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"HIV-1 p6 recruits PACSIN2 into virus-like particles independently of TSG101/ALIX; HIV-1 spreading in T cells and PBMCs is severely impaired upon PACSIN2 depletion and can be restored by wild-type PACSIN2 but not by an SH3-domain mutant unable to interact with WASP/N-WASP, indicating PACSIN2 promotes HIV-1 cell-to-cell spread by connecting Gag to the actin cytoskeleton via its SH3 domain.\",\n      \"method\": \"VLP incorporation assay, siRNA knockdown, spreading assay, SH3 domain mutant rescue experiment\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — VLP recruitment assay, KD, domain-mutant rescue with clear mechanistic interpretation, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"29891700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PACSIN2 localizes to L. monocytogenes protrusions and promotes protrusion engulfment during bacterial cell-to-cell spread; RNAi knockdown of PACSIN2 reduces spread efficiency.\",\n      \"method\": \"RNAi screen, fluorescence microscopy, bacterial spread assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — focused functional KD with imaging, single lab, single method per finding\",\n      \"pmids\": [\"31242077\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PACSIN2 promotes apical endocytosis in intestinal epithelial cells; PACSIN2 KO mice show reduced microvillar numbers and membrane-lifting defects at brush borders, with loss of dynamin-2 from microvillar rootlets; inhibition of endocytosis phenocopies PACSIN2 loss, placing PACSIN2-dependent endocytic scission upstream of microvillar membrane morphology maintenance.\",\n      \"method\": \"PACSIN2 KO mouse, electron microscopy, live-cell endocytosis assay, dynamin2 localization by immunofluorescence\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO mouse with ultrastructural phenotype, epistasis via endocytosis inhibition, multiple orthogonal readouts, single lab\",\n      \"pmids\": [\"31390291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PACSIN2 interacts with HCV NS5A via the NS5A domain I and the PACSIN2 F-BAR region; NS5A prevents PKCα from binding PACSIN2, reducing phosphorylation of PACSIN2 at S313 and enhancing NS5A–PACSIN2 interaction; PACSIN2 is required for HCV assembly (not entry or replication) and promotes NS5A–core protein interaction and lipid droplet formation via ERK1/2.\",\n      \"method\": \"Co-immunoprecipitation, pulldown assay, immunofluorescence, siRNA knockdown, S313A mutagenesis, viral infectivity assay\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, domain mapping, mutagenesis, KD with viral assembly phenotype, multiple orthogonal methods in single lab\",\n      \"pmids\": [\"31801866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PACSIN2 recruits trafficking regulators EHD4 and MICAL-L1 to the rear end of asymmetric adherens junctions to form a recycling endosome-like tubular structure; this PACSIN2/EHD4/MICAL-L1 complex controls local VE-cadherin trafficking and coordinates polarized endothelial migration and angiogenic sprouting.\",\n      \"method\": \"Co-immunoprecipitation, live-cell imaging, siRNA knockdown, in vivo zebrafish angiogenesis assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — complex formation by Co-IP, functional KD, in vivo validation, multiple orthogonal methods, single lab\",\n      \"pmids\": [\"33972531\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PACSIN2 colocalizes and physically interacts with nephrin in podocytes; PACSIN2 overexpression increases both nephrin endocytosis and recycling; rabenosyn-5 is identified as a novel PACSIN2 interactor that enhances the PACSIN2–nephrin association; palmitate (elevated in diabetes) further enhances this association.\",\n      \"method\": \"Co-immunoprecipitation, co-localization microscopy, overexpression endocytosis assay, pull-down\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, functional overexpression assay with trafficking readout, multiple interaction partners identified, single lab\",\n      \"pmids\": [\"28550045\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PACSIN2 loss increases plasma membrane expression of EGFR in resting cells and enhances EGF-induced EGFR phosphorylation, Erk and Akt activation, and cell proliferation; internalized EGF and activated EGFR translocate to PACSIN2-positive endosomes, identifying PACSIN2 as a regulator of EGFR surface levels and downstream signaling.\",\n      \"method\": \"siRNA knockdown, surface EGFR quantification, phospho-immunoblotting, proliferation assay, confocal co-localization\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD with multiple downstream signaling readouts and imaging, single lab\",\n      \"pmids\": [\"23129763\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Xenopus PACSIN2 localizes to the plasma membrane via its coiled-coil domain; overexpression inhibits gastrulation, fibronectin fibrillogenesis, and ectodermal cell spreading on fibronectin; PACSIN2 overexpression prevents integrin β1 localization to focal adhesions and filamin localization to stress fibers in XTC cells, indicating PACSIN2 regulates activated α5β1 integrin and cytoskeletal organization during cell migration.\",\n      \"method\": \"Overexpression and truncation mutant analysis in Xenopus embryos, immunofluorescence, cell spreading assay on fibronectin, mitochondria-anchoring sequestration experiment\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain mutant analysis, multiple orthogonal readouts, in vivo and cell culture validation, single lab\",\n      \"pmids\": [\"18495106\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PACSIN2 acts as a scaffold in CML cells: it binds Cobll1 and separately binds and inhibits SH3BP1 (a Rac1 pathway activator); Cobll1 preferentially competes with SH3BP1 for PACSIN2 binding, releasing SH3BP1 to activate Rac1 signaling and suppress TKI-induced apoptosis, leading to drug resistance.\",\n      \"method\": \"Co-immunoprecipitation, competitive binding assay, siRNA knockdown, apoptosis assay in K562 cells\",\n      \"journal\": \"Cancer medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, competitive binding with affinity measurement, functional KD, single lab\",\n      \"pmids\": [\"35352878\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Super-resolution microscopy shows that PACSIN2 and EHD2 both localize at caveolin-1-positive caveolae, with PACSIN2 F-BAR domain positioned closer to the plasma membrane than EHD2 and caveolin-1, suggesting PACSIN2 connects caveolae to the plasma membrane; PACSIN2 and EHD2 are present predominantly at typically sized (full-volume) caveolae.\",\n      \"method\": \"Single-molecule localization super-resolution (3D-STORM/PALM), spatial proximity clustering analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — high-resolution structural localization with quantitative analysis, single lab, no functional perturbation\",\n      \"pmids\": [\"35834519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PACSIN2 inhibits autophagy, putatively by interacting with LC3-II via a LIR motif to inhibit autophagosome formation; knockdown of PACSIN2 modulates mercaptopurine-induced cytotoxicity in intestinal cells; PACSIN2 modulates cellular TPMT activity via mechanisms distinct from its autophagy regulation.\",\n      \"method\": \"siRNA knockdown, autophagy flux assay, co-immunoprecipitation (PACSIN2–LC3-II), LIR motif analysis, cytotoxicity assay\",\n      \"journal\": \"Life science alliance\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with LC3-II, KD functional assay, domain motif analysis; single lab but multiple complementary approaches\",\n      \"pmids\": [\"36596605\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PACSIN2 phosphorylation at S313 is increased in diabetic kidney disease glomeruli; pS313-PACSIN2 decreases N-WASP degradation; N-WASP inhibition reciprocally triggers PACSIN2 S313 phosphorylation; pS313-PACSIN2 regulates actin cytoskeleton rearrangement in podocytes, and the dynamic phosphorylation cycle is required for podocyte morphology maintenance.\",\n      \"method\": \"Phospho-specific antibody staining in rat DKD glomeruli, pharmacological N-WASP inhibition, phospho-mimetic and phospho-dead PACSIN2 mutants, actin cytoskeleton imaging\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo disease model, mutagenesis, pharmacological epistasis, single lab\",\n      \"pmids\": [\"37296607\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PACSIN2 negatively regulates platelet integrin β1 hemostatic function through its interaction with filamin A; Pacsin2-/- mice display thrombocytopenia, prolonged bleeding, unstable thrombi, and hyperactive integrin β1; genetic deletion of integrin β1 in Pacsin2-/- mice normalizes platelet count, hemostasis, and thrombus formation, placing PACSIN2 upstream of integrin β1 activation.\",\n      \"method\": \"Pacsin2 KO mouse, integrin β1 KO epistasis, ferric chloride and laser injury thrombosis models, spreading assay on GFOGER, active integrin β1 antibody (9EG7) staining, FlnA-binding peptide pull-down\",\n      \"journal\": \"Journal of thrombosis and haemostasis\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO mouse with multiple functional readouts, genetic epistasis rescue, biochemical pull-down, single lab but highly rigorous multi-method design\",\n      \"pmids\": [\"37678551\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In zebrafish larvae, pacsin2 is enriched at the apical pole of renal proximal tubule cells at endocytic structures; loss of pacsin2 reduces endocytosis in the proximal tubule and decreases abundance of megalin and endocytic organelles.\",\n      \"method\": \"Pacsin2 morpholino knockdown in zebrafish, fluorescence microscopy, endocytosis assay, megalin immunostaining\",\n      \"journal\": \"Biology open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — in vivo KD with localization and functional endocytosis readout, single lab, zebrafish model\",\n      \"pmids\": [\"35616009\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In hippocampal CA1 neurons, chronic stress upregulates PACSIN2; PACSIN2 physically interacts with dynamin and cooperatively modulates postsynaptic GluA1 AMPA receptor expression; selective knockdown of PACSIN2 in dCA1 enhances synaptic transmission and ameliorates depression-like behaviors in rats.\",\n      \"method\": \"Co-immunoprecipitation (PACSIN2–dynamin), viral-vector-mediated knockdown in dCA1, electrophysiology, behavioral assays\",\n      \"journal\": \"Acta pharmacologica Sinica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP, region-specific KD with electrophysiology and behavioral readouts, single lab\",\n      \"pmids\": [\"42098399\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PACSIN2 knockdown in human leukemia cells (NALM6) results in significantly lower TPMT activity, and a PACSIN2 SNP (rs2413739) is associated with altered TPMT activity in patients; protein-level correlation between PACSIN2 and TPMT was detected in PBMCs.\",\n      \"method\": \"siRNA knockdown with TPMT activity assay, genome-wide association in HapMap cell lines, patient cohort validation\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-based KD with enzymatic activity readout plus independent human cohort replication, but mechanism of PACSIN2–TPMT regulation not molecularly characterized\",\n      \"pmids\": [\"22846425\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PACSIN2 is an F-BAR domain membrane-sculpting protein that shapes caveolae by directly binding caveolin-1 and recruiting dynamin-2 for fission, with PKC-mediated phosphorylation at S313 acting as a molecular switch that reduces membrane binding and triggers caveolae removal; beyond caveolae, PACSIN2 regulates clathrin-independent endocytosis, VE-cadherin and nephrin trafficking, EGFR surface levels, integrin β1 activation (via filamin A), Rac1 signaling, actin cytoskeleton organization (via N-WASP and WASP/N-WASP SH3-domain interactions), autophagy (via LC3-II interaction), and serves as a proviral factor exploited by HIV-1, HCV, C. difficile TcdA, and L. monocytogenes.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PACSIN2 is an F-BAR domain membrane-sculpting protein that couples plasma membrane remodeling to dynamin-dependent membrane scission and to the actin cytoskeleton across endocytic and cell-junction contexts [#0, #3]. At caveolae, its F-BAR domain directly binds caveolin-1, sculpts caveolar invaginations, and recruits dynamin-2 for fission [#0]; super-resolution imaging places the PACSIN2 F-BAR closer to the plasma membrane than EHD2 and caveolin-1, positioning it as the link between caveolae and the membrane [#17]. PKC phosphorylation at serine 313 acts as a switch that reduces PACSIN2 membrane binding and tubulation, shortening caveolar lifetime and triggering dynamin-2-driven caveolae removal, with EHD2 restoring caveolar stability [#5]. Distinctively among BAR/F-BAR proteins, the PACSIN2 F-BAR binds actin filaments through the same concave surface used for membrane binding [#3], and Filamin A binds the F-BAR tip to enhance tubulation and direct PACSIN2 localization [#4]. Through these activities PACSIN2 drives clathrin-independent and apical endocytosis and regulates surface trafficking of multiple cargoes: it restrains VE-cadherin internalization at tension-bearing adherens junctions by organizing an EHD4/MICAL-L1 recycling-endosome-like tubular structure to coordinate polarized endothelial migration and angiogenic sprouting [#6, #12], controls nephrin endocytosis and recycling in podocytes [#13], limits surface EGFR and downstream Erk/Akt signaling [#14], and maintains brush-border microvillar morphology via dynamin-2-dependent apical endocytic scission [#10]. PACSIN2 negatively regulates Rac1 activity through its membrane-tubulating and dynamin-dependent functions and a Rac1 hypervariable-domain interaction [#1], and acts as a scaffold balancing Cobll1 and SH3BP1 to tune Rac1 signaling [#16]. It negatively regulates integrin \\u03b21 activation via Filamin A, with Pacsin2 deletion causing thrombocytopenia and unstable thrombi that are normalized by integrin \\u03b21 deletion [#20]. PACSIN2 also serves as a host factor exploited by pathogens, promoting HIV-1 cell-to-cell spread by linking Gag to actin through its SH3-domain interaction with WASP/N-WASP [#8], supporting HCV assembly via NS5A binding [#11], and mediating entry of C. difficile TcdA and spread of L. monocytogenes [#7, #9].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established the earliest functional readout for PACSIN2 as an SH3-domain adaptor that negatively regulates a transmembrane partner during development.\",\n      \"evidence\": \"Pull-down, colocalization, and developmental rescue with \\u0394SH3 mutant of Xenopus PACSIN2 against ADAM13\",\n      \"pmids\": [\"11076687\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Performed on Xenopus ortholog only\", \"Did not address membrane-sculpting or endocytic roles\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Linked PACSIN2 to integrin \\u03b21 and cytoskeletal organization during cell migration, foreshadowing its later integrin-regulatory role.\",\n      \"evidence\": \"Overexpression and truncation analysis in Xenopus embryos and XTC cells with fibronectin spreading assays\",\n      \"pmids\": [\"18495106\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Largely overexpression-based\", \"Molecular basis of integrin regulation not defined here\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined the core mechanism: the F-BAR domain directly binds caveolin-1, sculpts caveolae, and recruits dynamin-2 for fission, establishing PACSIN2 as a caveolar membrane-sculpting protein.\",\n      \"evidence\": \"Direct F-BAR\\u2013caveolin-1 binding, membrane tubulation assay, and siRNA knockdown with morphological readout\",\n      \"pmids\": [\"21610094\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish regulatory switch controlling fission timing\", \"In vitro tubulation versus physiological caveolar dynamics\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showed PACSIN2 negatively regulates Rac1 activity through its membrane-tubulating and dynamin-dependent functions, connecting it to migration control.\",\n      \"evidence\": \"Co-IP, Rac1-GTP pull-down, wound-healing migration assay, and live imaging with interaction- and tubulation-dependent rescue\",\n      \"pmids\": [\"21693584\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct versus endosome-mediated regulation of Rac1 not fully resolved\", \"GEF/GAP intermediary not identified in this study\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Revealed that the F-BAR domain binds actin filaments via the same concave surface used for membranes, a property unique to PACSIN2 among tested F-BAR proteins, coupling membrane and cytoskeletal functions.\",\n      \"evidence\": \"In vitro actin co-sedimentation with mutagenesis of the membrane-binding surface and structural context\",\n      \"pmids\": [\"25216944\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Competition between membrane and actin binding in cells not quantified\", \"Physiological consequence of dual binding not directly tested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified Filamin A as an F-BAR tip-binding partner that enhances tubulation and directs PACSIN2 localization, controlling demarcation membrane formation in megakaryocytes.\",\n      \"evidence\": \"Reciprocal Co-IP in platelets, in vitro tubulation, and Flna-null mouse morphology\",\n      \"pmids\": [\"25838348\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not connect FlnA interaction to integrin function directly\", \"Mechanism of tubulation enhancement not structurally resolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Established PKC phosphorylation of S313 as the molecular switch that reduces membrane binding and triggers dynamin-2-dependent caveolae removal, explaining how caveolar lifetime is regulated.\",\n      \"evidence\": \"S313E phospho-mimetic mutagenesis, live-cell caveolar tracking, PKC activation, and EHD2 rescue\",\n      \"pmids\": [\"26092940\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo PKC isoform specificity at S313 not fully defined here\", \"Crosstalk with actin binding not addressed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showed PACSIN2 is recruited by tension to trailing adherens junctions and inhibits VE-cadherin internalization, defining a role in endothelial barrier integrity.\",\n      \"evidence\": \"siRNA knockdown, photoconversion/FRAP, super-resolution and live-cell imaging, F-BAR mutant analysis\",\n      \"pmids\": [\"27417273\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tension-sensing mechanism of recruitment not molecularly defined\", \"Trafficking machinery downstream identified only later\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstrated PACSIN2 mediates a clathrin- and caveolae-independent but dynamin-dependent endocytic route, exploited by C. difficile toxin A.\",\n      \"evidence\": \"RNAi knockdown, pharmacological inhibition, and confocal imaging of labeled TcdA\",\n      \"pmids\": [\"27942025\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct toxin\\u2013PACSIN2 interaction not shown\", \"Cargo selectivity of this pathway unresolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Extended cargo regulation to nephrin trafficking in podocytes and identified rabenosyn-5 as a partner enhancing the association, with disease-relevant palmitate modulation.\",\n      \"evidence\": \"Co-IP, colocalization, overexpression endocytosis/recycling assay, and pull-down\",\n      \"pmids\": [\"28550045\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relies on overexpression for trafficking readout\", \"Endogenous physiological balance of endocytosis versus recycling unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined a proviral role where PACSIN2 connects HIV-1 Gag to the actin cytoskeleton via its SH3 domain to promote cell-to-cell spread.\",\n      \"evidence\": \"VLP incorporation, siRNA knockdown, spreading assay, and SH3-mutant rescue in T cells and PBMCs\",\n      \"pmids\": [\"29891700\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural detail of Gag\\u2013SH3 interaction not resolved\", \"Whether membrane sculpting contributes alongside SH3 not separated\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed PACSIN2-dependent endocytic scission maintains apical microvillar membrane morphology, and supports L. monocytogenes protrusion engulfment.\",\n      \"evidence\": \"PACSIN2 KO mouse ultrastructure with dynamin-2 mislocalization, and RNAi bacterial spread assay\",\n      \"pmids\": [\"31390291\", \"31242077\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cargo whose endocytosis maintains microvilli not identified\", \"Listeria engulfment mechanism only correlative\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Revealed HCV exploitation: NS5A binds the F-BAR region and blocks PKC\\u03b1-mediated S313 phosphorylation, linking the phospho-switch to viral assembly.\",\n      \"evidence\": \"Co-IP, domain mapping, S313A mutagenesis, knockdown, and infectivity assays\",\n      \"pmids\": [\"31801866\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How reduced phosphorylation mechanistically aids assembly not fully defined\", \"Role of lipid-droplet ERK1/2 axis only partially mapped\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified the PACSIN2/EHD4/MICAL-L1 tubular recycling complex that controls local VE-cadherin trafficking and polarized endothelial migration and sprouting.\",\n      \"evidence\": \"Co-IP, live imaging, siRNA knockdown, and in vivo zebrafish angiogenesis\",\n      \"pmids\": [\"33972531\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Assembly hierarchy of the complex not fully ordered\", \"Direct versus indirect EHD4/MICAL-L1 binding not separated\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Refined the spatial model of caveolae by placing PACSIN2 F-BAR closest to the membrane and identified a Cobll1/SH3BP1 scaffold switch tuning Rac1-dependent drug resistance.\",\n      \"evidence\": \"Single-molecule super-resolution clustering analysis; competitive Co-IP and apoptosis assays in K562 cells; zebrafish proximal tubule endocytosis\",\n      \"pmids\": [\"35834519\", \"35352878\", \"35616009\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Super-resolution lacked functional perturbation\", \"Scaffold competition affinities measured in single system\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Established disease-context roles: S313 phosphorylation regulates podocyte actin via N-WASP, and PACSIN2 restrains platelet integrin \\u03b21 via Filamin A in hemostasis.\",\n      \"evidence\": \"Phospho-specific staining in DKD glomeruli with phospho-mutants; Pacsin2 KO and integrin \\u03b21 KO epistasis with thrombosis models and FlnA pull-down\",\n      \"pmids\": [\"37296607\", \"37678551\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase/phosphatase cycle governing S313 in vivo not fully mapped\", \"How FlnA binding suppresses integrin activation mechanistically unresolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Implicated PACSIN2 in autophagy inhibition via a putative LIR-LC3-II interaction and in modulation of thiopurine drug response.\",\n      \"evidence\": \"siRNA knockdown, autophagy flux, LC3-II Co-IP, LIR analysis, and cytotoxicity assays\",\n      \"pmids\": [\"36596605\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"LIR-mediated LC3-II binding described as putative\", \"Mechanism linking PACSIN2 to TPMT activity not molecularly defined\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Extended PACSIN2 function to neurons, where it cooperates with dynamin to control GluA1 AMPA receptor expression and influences stress-related behavior.\",\n      \"evidence\": \"Co-IP, region-specific knockdown in dCA1, electrophysiology, and behavioral assays in rats\",\n      \"pmids\": [\"42098399\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether GluA1 regulation reflects endocytic scission not directly shown\", \"Single model system\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How PACSIN2's dual membrane- and actin-binding F-BAR surface is dynamically partitioned and regulated in vivo, and how a single scission machinery is selectively deployed across caveolae, junctions, podocytes, microvilli, and neurons, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified structural model integrating membrane, actin, and phospho-switch states\", \"Cargo-selection logic across tissues undefined\", \"Endogenous kinase/phosphatase control of S313 in each context unmapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [12, 16]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 20]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 17, 6]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [1, 12, 14]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [2, 7]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [3, 15]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8856828\", \"supporting_discovery_ids\": [0, 10]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [7, 12, 13]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 14, 16]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [8, 11, 7]},\n      {\"term_id\": \"R-HSA-109582\", \"supporting_discovery_ids\": [20]}\n    ],\n    \"complexes\": [\n      \"PACSIN2/EHD4/MICAL-L1 tubular recycling complex\"\n    ],\n    \"partners\": [\n      \"CAV1\",\n      \"DNM2\",\n      \"FLNA\",\n      \"RAC1\",\n      \"WASL\",\n      \"EHD2\",\n      \"MICALL1\",\n      \"NPHS1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}