{"gene":"PLSCR1","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":1998,"finding":"Human PLSCR1 (MmTRA1b) was identified as the plasma membrane phospholipid scramblase required for transbilayer movement of membrane phospholipids; the predicted amino acid sequence showed perfect identity with the human plasma membrane phospholipid scramblase.","method":"cDNA cloning, sequence analysis, and expression studies in U937 cells","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — sequence identity established functional assignment, expression correlation during differentiation, single lab","pmids":["9712717"],"is_preprint":false},{"year":2004,"finding":"PLSCR1 is present in plasma membranes of non-permeabilized neutrophils and is also located in secretory vesicles and tertiary and secondary granules; it is enriched in detergent-insoluble membranes (lipid rafts) and co-localizes with raft markers at the neutrophil uropod following fMLP stimulation. Phospholipid flip-flop activity (PS exposure and uptake) also localizes to this uropod domain. fMLP stimulation did not significantly alter PLSCR1 surface labeling, suggesting stimulated phospholipid flip-flop does not require additional mobilization of PLSCR1 to the plasma membrane.","method":"Flow cytometry with anti-PLSCR1 antibodies, subcellular fractionation, detergent-insoluble membrane isolation, live-cell fluorescent lipid uptake assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (flow cytometry, fractionation, lipid probes), single lab","pmids":["14766753"],"is_preprint":false},{"year":2005,"finding":"PLSCR1 augments UV-induced apoptosis primarily through the intrinsic (caspase-9) apoptotic pathway rather than the extrinsic (caspase-8) pathway. A PLSCR1 mutant with alanine substitution at the PKC-delta phosphorylation site enhanced UV-induced apoptosis to the same level as wild-type PLSCR1, indicating that direct phosphorylation of PLSCR1 by PKC-delta is not required for PLSCR1-enhanced scramblase activity during apoptosis.","method":"Caspase inhibitor pharmacology, site-directed mutagenesis (Ala substitution at PKC-delta phosphorylation site), transfection, apoptosis assays","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis plus pathway inhibitor experiments, single lab, two orthogonal approaches","pmids":["15863367"],"is_preprint":false},{"year":2006,"finding":"Inducible overexpression of PLSCR1 in U937 myeloid leukemic cells arrested proliferation at G1 phase and promoted granulocyte-like differentiation, increased CDK inhibitors p27(Kip1) and p21(Cip1), downregulated SKP2, decreased c-Myc and Bcl-2 proteins, and increased sensitivity to etoposide-induced apoptosis. PLSCR1 localization is regulated by its palmitoylation state, with palmitoylated PLSCR1 at the membrane and depalmitoylated form in the nucleus.","method":"Tetracycline-inducible expression system, flow cytometry (cell cycle), Western blotting","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — inducible expression with defined cellular phenotype and multiple molecular markers, single lab","pmids":["16702944"],"is_preprint":false},{"year":2011,"finding":"PLSCR1 physically interacts with all three RELT family members (RELT, RELL1, RELL2) as identified by yeast two-hybrid screening and confirmed by co-immunoprecipitation. OSR1 kinase phosphorylates PLSCR1 in vitro only in the presence of RELT, suggesting formation of a functional multiprotein RELT-OSR1-PLSCR1 complex. RELT overexpression alters the intracellular localization of PLSCR1.","method":"Yeast two-hybrid screen, co-immunoprecipitation, in vitro kinase assay, fluorescence co-localization","journal":"Molecular and cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus reciprocal Co-IP plus in vitro kinase assay, single lab, multiple orthogonal methods","pmids":["22052202"],"is_preprint":false},{"year":2013,"finding":"Wogonoside promotes PLSCR1 nuclear translocation in AML cells, where nuclear PLSCR1 binds to the IP3R1 promoter and increases IP3R1 expression; PLSCR1 knockdown partially blocked wogonoside-induced G1 cell cycle arrest and differentiation.","method":"siRNA knockdown, ChIP, immunostaining, Western blotting, flow cytometry","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP demonstrating promoter binding, siRNA rescue experiments, multiple orthogonal methods, single lab","pmids":["23487022"],"is_preprint":false},{"year":2015,"finding":"PLSCR1 induction by dsDNA transfection in ovarian epithelial cells is mediated by the STING/IRF3 pathway: IRF3 siRNA knockdown or STING siRNA knockdown markedly reduced PLSCR1 protein induction, while MAPK inhibition had no effect. De novo synthesized PLSCR1 localized predominantly to the plasma membrane.","method":"siRNA knockdown of STING and IRF3, kinase inhibitor (U0126), Western blotting, immunofluorescence","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA epistasis for two pathway components with localization data, single lab, two orthogonal knockdown experiments","pmids":["25658875"],"is_preprint":false},{"year":2017,"finding":"Nuclear PLSCR1 binds the IP3R1 promoter in primary AML cells, leading to IP3R1 upregulation, release of Ca2+ from the endoplasmic reticulum, and AML cell differentiation; this PLSCR1/IP3R1/Ca2+ axis mediates wogonoside's anti-leukemic effects.","method":"ChIP, Ca2+ flux measurements, in vivo xenograft (NOD/SCID mice), Western blotting","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP, Ca2+ measurements, in vivo validation, single lab, multiple orthogonal methods","pmids":["28492556"],"is_preprint":false},{"year":2018,"finding":"Nuclear translocation of PLSCR1 in primary AML cells is dependent on depalmitoylation mediated by acyl protein thioesterase 1 (APT-1); wogonoside induces APT-1-mediated depalmitoylation of PLSCR1, enabling its nuclear trafficking.","method":"Depalmitoylation assay, inhibitor studies, Western blotting, immunofluorescence","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — biochemical depalmitoylation assay with APT-1 connection and localization data, single lab","pmids":["29377576"],"is_preprint":false},{"year":2020,"finding":"Phosphorylation of PLSCR1 at Tyr69/74 drives its nuclear translocation in basal-like breast cancer cells. Nuclear PLSCR1 is enriched at the STAT1 promoter and enhances STAT3 binding to the STAT1 promoter, leading to STAT1 transactivation, which promotes cancer stem cell properties and BLBC progression.","method":"Immunostaining, co-IP, ChIP, quantitative RT-PCR, siRNA knockdown, in vitro and in vivo tumorigenesis assays","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP, Co-IP, and functional rescue with multiple orthogonal methods, single lab","pmids":["32292520"],"is_preprint":false},{"year":2022,"finding":"PLSCR1 restricts human cytomegalovirus (HCMV) replication by repressing transcription from viral major immediate early (MIE) and early promoters; PLSCR1 expression reduced levels of CREB•IE2 and CBP•IE2 complexes important for viral early promoter transactivation. PLSCR1-KO cells showed significantly increased HCMV plaque formation and MIE gene expression.","method":"PLSCR1-knockout cell lines, reporter gene assays (CRE- and MIE promoter-driven), co-immunoprecipitation, plaque assay","journal":"Microbiology spectrum","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO cells plus reporter assays plus Co-IP, single lab, multiple orthogonal methods","pmids":["35138119"],"is_preprint":false},{"year":2022,"finding":"ILDR1 was identified as a novel PLSCR1-binding partner by yeast two-hybrid screening; ILDR1 competes with influenza A virus NP protein for binding to PLSCR1, disrupting the antiviral PLSCR1-NP interaction. Plscr1-/- mice are more susceptible to H1N1 infection. The PLSCR1-ILDR1-NP regulatory pathway limits IAV infection.","method":"Yeast two-hybrid screening, co-immunoprecipitation, Plscr1-/- mouse infection model","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus Co-IP plus in vivo knockout model, single lab","pmids":["35595813"],"is_preprint":false},{"year":2023,"finding":"PLSCR1 is a potent cell-autonomous restriction factor against SARS-CoV-2 identified by parallel genome-wide CRISPR-Cas9 screens in human lung epithelia and hepatocytes. IFNγ-induced PLSCR1 interferes with both endocytic and TMPRSS2-dependent fusion entry routes. Whole-cell 4Pi nanoscopy and bipartite nano-reporter assays showed PLSCR1 targets SARS-CoV-2-containing vesicles to prevent spike-mediated fusion and viral escape. The C-terminal β-barrel domain—but not lipid scramblase enzymatic activity—is essential for this fusogenic blockade.","method":"Genome-wide CRISPR-Cas9 screens, 4Pi single-molecule switching nanoscopy, bipartite nano-reporter fusion assays, domain mutagenesis, multiple viral lineage testing, bat and mouse functional conservation studies","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — parallel CRISPR screens, nanoscopy, fusion reporter assays, domain mutagenesis, multiple orthogonal methods in one rigorous study","pmids":["37438530"],"is_preprint":false},{"year":2024,"finding":"Genome-wide arrayed CRISPR knockout screen confirmed PLSCR1 as an IFN-stimulated gene that restricts spike-mediated SARS-CoV-2 entry specifically via the endocytic route; TMPRSS2 overexpression alleviated PLSCR1-mediated restriction. PLSCR1 did not contribute to IFN signaling per se but restricted viral entry. Recent SARS-CoV-2 variants have adapted to circumvent PLSCR1 restriction.","method":"Genome-wide arrayed CRISPR knockout screen, TMPRSS2 overexpression epistasis, integrated analysis of 67 large-scale studies","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — arrayed genome-wide CRISPR screen with epistasis experiments, replicated independently of Xu et al. 2023","pmids":["39316623"],"is_preprint":false},{"year":2021,"finding":"KPNA2 (importin α2) interacts with endogenous PLSCR1 and mediates its nuclear accumulation in radioresistant lung adenocarcinoma cells; PLSCR1 knockdown suppressed KPNA2-induced radioresistance. A positive feedback loop between nuclear PLSCR1 and STAT1 modulates cancer stem cell characteristics and radioresistance.","method":"Co-immunoprecipitation, siRNA knockdown, next-generation sequencing, functional radioresistance assays","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus siRNA functional rescue, single lab, two orthogonal methods","pmids":["34773335"],"is_preprint":false},{"year":2025,"finding":"NEDD4-2 (NEDD4L) ubiquitin ligase directly interacts with and ubiquitinates PLSCR1, regulating its protein stability. NEDD4-2 deficiency in cells and mouse kidney increased PLSCR1 protein levels, enhanced phosphatidylserine exposure in response to calcium and apoptotic stimuli, and increased macrophage clearance of apoptotic cells.","method":"Affinity purification mass spectrometry, co-immunoprecipitation, ubiquitination assay, NEDD4-2 KO cells and mouse kidney model, annexin V/flow cytometry, macrophage clearance assay","journal":"Cell death discovery","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — AP-MS plus Co-IP plus KO model with functional readout, single lab, multiple orthogonal methods","pmids":["40835608"],"is_preprint":false},{"year":2025,"finding":"PLSCR1 acts as a transcriptional activator of IFN-λR1 (IFNLR1) by directly binding to its promoter after IAV infection, and also interacts with IFN-λR1 protein on the cell surface of pulmonary epithelial cells to modulate IFN-λ signaling. Plscr1-/- mice show impaired Ifn-λr1 and downstream ISG expression upon IAV infection. The lipid scramblase enzymatic activity of PLSCR1 is dispensable for its anti-influenza activity.","method":"ChIP (promoter binding), co-immunoprecipitation (IFN-λR1 interaction), Plscr1-/- mouse model, Plscr1-overexpressing (Foxj1-Cre+) mice, transcriptomic analysis, single-cell RNA sequencing","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP plus Co-IP plus two independent genetic mouse models (KO and overexpressor) with functional readouts, multiple orthogonal methods in one study","pmids":["41439508"],"is_preprint":false},{"year":2025,"finding":"PLSCR1 restricts HIV-1 entry by blocking virion-cell and cell-cell membrane fusion mediated by the HIV-1 envelope glycoprotein (Env), without affecting CD4 or CXCR4 surface expression or virus binding to cells. This restriction is broad-spectrum (HIV-1 diverse tropisms/subtypes, HIV-2, SIV) and independent of type I IFN signaling.","method":"Multiple cell types (SupT1, purified CD4+ T cells), fusion assays, cell-to-cell transmission assays, receptor expression analysis, viral replication assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple cell types and virus strains with direct fusion assays, single lab","pmids":["41004226"],"is_preprint":false},{"year":2025,"finding":"PLSCR1 inhibits SARS-CoV-2 entry by specifically downregulating plasma membrane expression of ACE2 (the viral receptor) without affecting total cellular ACE2 levels. PLSCR1 KO cells showed enhanced cellular entry of both pseudotyped and authentic SARS-CoV-2.","method":"109 ISG-knockout cell lines screen, PLSCR1 KO and overexpression, pseudotyped and authentic virus entry assays, flow cytometry for surface ACE2","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO plus overexpression with direct surface receptor quantification, single lab, two orthogonal entry assays","pmids":["39945535"],"is_preprint":false},{"year":2026,"finding":"PLSCR1 interacts with EGFR and promotes its phosphorylation and activation of the MAPK signaling pathway in chemoresistant TNBC cells, leading to upregulation of efflux pumps P-gp and MRP1. Concurrently, PLSCR1 mRNA is stabilized via METTL3-mediated m6A modification recognized by the m6A reader IGF2BP3.","method":"Co-immunoprecipitation (PLSCR1-EGFR), siRNA knockdown, Western blotting, in vitro and in vivo functional assays, m6A modification analysis","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus KD functional rescue plus m6A analysis, single lab, multiple orthogonal methods","pmids":["42140933"],"is_preprint":false},{"year":2025,"finding":"FOXA1 transcriptionally represses PLSCR1 by binding to the PLSCR1 promoter in tongue squamous cell carcinoma cells, as demonstrated by ChIP and dual-luciferase assays; PLSCR1 knockdown inhibited TSCC cell proliferation, migration, and invasion, while FOXA1 overexpression inhibited TSCC progression in a PLSCR1-dependent manner.","method":"ChIP, dual-luciferase reporter assay, siRNA knockdown, lentiviral overexpression, xenograft mouse model","journal":"Cell biochemistry and biophysics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus reporter assay plus rescue experiments, single lab","pmids":["40445264"],"is_preprint":false},{"year":2025,"finding":"PLSCR1 regulates the proliferation, apoptosis, and inflammatory cytokine production (TNF-α, IL-1β, IL-6) of fibroblast-like synoviocytes by modulating STAT1 signaling; STAT1 activation rescued the effects of PLSCR1 knockdown, placing PLSCR1 upstream of STAT1 in this pathway.","method":"siRNA knockdown, STAT1 activator rescue (2-NP), EdU proliferation assay, flow cytometry (apoptosis), ELISA (cytokines)","journal":"Immunity, inflammation and disease","confidence":"Low","confidence_rationale":"Tier 3 / Weak — siRNA plus pharmacological rescue, single lab, single method per readout","pmids":["41146421"],"is_preprint":false}],"current_model":"PLSCR1 is an interferon-inducible, multiply palmitoylated plasma membrane protein that functions as a cell-autonomous antiviral restriction factor (against SARS-CoV-2, HIV-1, HCMV, and influenza A virus) by blocking spike/Env-mediated membrane fusion and viral entry—via its C-terminal β-barrel domain rather than lipid scramblase enzymatic activity—while also trafficking to the nucleus upon depalmitoylation (mediated by APT-1) or Tyr69/74 phosphorylation, where it binds gene promoters (IP3R1, STAT1, IFN-λR1) to regulate transcription; its protein stability is controlled by NEDD4-2-mediated ubiquitination, it participates in multiprotein complexes with RELT family members and OSR1, and it interacts with EGFR to activate MAPK signaling in cancer cells."},"narrative":{"mechanistic_narrative":"PLSCR1 is an interferon-stimulated, palmitoylation-regulated plasma membrane protein that acts as a broad cell-autonomous antiviral restriction factor and a stimulus-dependent nuclear transcriptional regulator [PMID:37438530, PMID:23487022]. As a restriction factor it blocks enveloped-virus entry by interfering with glycoprotein-mediated membrane fusion: parallel genome-wide CRISPR screens established it as a potent SARS-CoV-2 restriction factor that targets virus-containing vesicles to prevent spike-mediated fusion through its C-terminal β-barrel domain rather than its lipid scramblase activity [PMID:37438530], a route-specific blockade of endocytic entry that is overcome by TMPRSS2 and circumvented by recent variants [PMID:39316623], and in part reflects downregulation of plasma-membrane ACE2 [PMID:39945535]. The same fusion-blocking activity, independent of lipid scramblase function and of type I IFN signaling, restricts HIV-1 Env-mediated fusion [PMID:41004226] and influenza A virus, where PLSCR1 binds the viral NP protein in a manner competed by ILDR1 [PMID:35595813]; PLSCR1 additionally restricts HCMV by repressing transcription from viral immediate-early and early promoters [PMID:35138119]. Beyond direct restriction, PLSCR1 traffics to the nucleus following APT-1–mediated depalmitoylation [PMID:29377576] or Tyr69/74 phosphorylation [PMID:32292520] and binds gene promoters to drive transcription of IP3R1 [PMID:23487022, PMID:28492556], STAT1 [PMID:32292520], and the IFN-λ receptor IFNLR1 [PMID:41439508], coupling it to calcium signaling, myeloid differentiation, and interferon responses. Its abundance is controlled by NEDD4-2–mediated ubiquitination [PMID:40835608], and it nucleates a RELT–OSR1–PLSCR1 multiprotein complex in which OSR1 phosphorylates PLSCR1 only in the presence of RELT [PMID:22052202]. In cancer, nuclear PLSCR1 promotes stem-cell properties and radioresistance via a STAT1 feedback loop [PMID:32292520, PMID:34773335] and engages EGFR to activate MAPK signaling and drug efflux [PMID:42140933].","teleology":[{"year":1998,"claim":"Established the founding biochemical identity of PLSCR1 as the plasma membrane phospholipid scramblase mediating transbilayer phospholipid movement, anchoring all subsequent functional work.","evidence":"cDNA cloning and sequence analysis with expression studies in U937 cells","pmids":["9712717"],"confidence":"Medium","gaps":["Functional assignment rested on sequence identity rather than reconstituted enzymatic assay","No structural basis for scramblase activity defined"]},{"year":2004,"claim":"Localized PLSCR1 and its lipid flip-flop activity to lipid-raft membrane domains at the stimulated neutrophil uropod, showing scramblase activity does not require new mobilization of the protein to the membrane.","evidence":"Flow cytometry, subcellular fractionation, and live-cell lipid uptake assays in neutrophils","pmids":["14766753"],"confidence":"Medium","gaps":["Did not resolve how flip-flop activity is triggered locally","Single cell type"]},{"year":2006,"claim":"Linked PLSCR1 to myeloid growth control and revealed that its palmitoylation state governs partitioning between membrane and nucleus, foreshadowing a dual-compartment function.","evidence":"Tetracycline-inducible overexpression in U937 cells with cell-cycle and apoptosis markers","pmids":["16702944"],"confidence":"Medium","gaps":["Mechanism connecting nuclear PLSCR1 to gene-expression changes not yet defined","Enzyme controlling palmitoylation cycle unidentified at this stage"]},{"year":2011,"claim":"Defined PLSCR1 as a scaffold in a RELT-OSR1 signaling complex where RELT is required for OSR1-mediated phosphorylation of PLSCR1, connecting it to kinase signaling.","evidence":"Yeast two-hybrid, reciprocal co-IP, in vitro kinase assay, and co-localization","pmids":["22052202"],"confidence":"Medium","gaps":["Functional consequence of RELT-OSR1-PLSCR1 phosphorylation not established","Phosphosite not mapped"]},{"year":2018,"claim":"Identified APT-1-mediated depalmitoylation as the molecular switch enabling PLSCR1 nuclear translocation, explaining the membrane-to-nucleus relocation observed earlier.","evidence":"Depalmitoylation assays, inhibitor studies and immunofluorescence in primary AML cells","pmids":["29377576"],"confidence":"Medium","gaps":["Whether other stimuli use the same APT-1 switch unknown","Nuclear import machinery not defined here"]},{"year":2017,"claim":"Resolved the nuclear function of PLSCR1 as direct transcriptional activation of IP3R1, coupling it to ER calcium release and leukemic-cell differentiation.","evidence":"ChIP, Ca2+ flux measurements, and NOD/SCID xenografts (extends siRNA/ChIP work from 2013)","pmids":["28492556","23487022"],"confidence":"Medium","gaps":["DNA sequence recognized by PLSCR1 not defined","Whether PLSCR1 binds DNA directly or via partners unresolved"]},{"year":2020,"claim":"Showed Tyr69/74 phosphorylation as an alternative trigger for nuclear translocation and identified a nuclear PLSCR1-STAT3-STAT1 promoter axis driving cancer stemness, generalizing the transcriptional role beyond IP3R1.","evidence":"ChIP, co-IP, RT-PCR, siRNA, and in vivo tumorigenesis in basal-like breast cancer","pmids":["32292520"],"confidence":"Medium","gaps":["Kinase phosphorylating Tyr69/74 not identified","Relationship between phosphorylation and depalmitoylation switches unclear"]},{"year":2021,"claim":"Identified KPNA2 as the import factor mediating PLSCR1 nuclear accumulation and placed a nuclear PLSCR1-STAT1 feedback loop in radioresistance.","evidence":"Co-IP, siRNA, NGS, and radioresistance assays in lung adenocarcinoma","pmids":["34773335"],"confidence":"Medium","gaps":["How depalmitoylation/phosphorylation feeds into KPNA2 recognition not shown","Direct nuclear localization signal not mapped"]},{"year":2022,"claim":"Extended PLSCR1 from a scramblase to an antiviral factor, demonstrating transcriptional repression of HCMV immediate-early/early promoters and disruption of CREB/CBP-IE2 complexes.","evidence":"PLSCR1-KO cells, reporter assays, co-IP and plaque assays","pmids":["35138119"],"confidence":"Medium","gaps":["Whether nuclear or membrane PLSCR1 mediates HCMV restriction unclear","Direct DNA binding to viral promoters not shown"]},{"year":2022,"claim":"Defined a PLSCR1-NP antiviral interaction against influenza A and identified ILDR1 as a competing binding partner, with in vivo confirmation in Plscr1-/- mice.","evidence":"Yeast two-hybrid, co-IP, and Plscr1-/- mouse H1N1 infection","pmids":["35595813"],"confidence":"Medium","gaps":["Domain mediating NP binding not mapped","Physiological trigger regulating ILDR1 competition unknown"]},{"year":2023,"claim":"Established PLSCR1 as a potent IFN-induced cell-autonomous SARS-CoV-2 restriction factor that blocks spike-mediated fusion at virus-containing vesicles via its C-terminal β-barrel, decoupling restriction from lipid scramblase activity.","evidence":"Genome-wide CRISPR screens, 4Pi nanoscopy, fusion reporter assays and domain mutagenesis","pmids":["37438530"],"confidence":"High","gaps":["Molecular mechanism by which the β-barrel blocks fusion not fully resolved","Host/viral binding partner at the vesicle not identified"]},{"year":2024,"claim":"Independently confirmed PLSCR1 as an ISG restricting SARS-CoV-2 entry specifically via the endocytic route and showed TMPRSS2 bypass and variant adaptation, refining the restriction model.","evidence":"Arrayed genome-wide CRISPR screen with TMPRSS2 epistasis and meta-analysis","pmids":["39316623"],"confidence":"High","gaps":["Viral determinants of variant escape not defined","Why restriction is endocytic-route specific not mechanistically explained"]},{"year":2025,"claim":"Generalized the entry-blocking activity to HIV-1, SIV and HIV-2, showing PLSCR1 blocks Env-mediated fusion without affecting receptor expression or binding, IFN-independently.","evidence":"Fusion and cell-to-cell transmission assays across multiple cell types and viral strains","pmids":["41004226"],"confidence":"Medium","gaps":["Whether HIV-1 restriction uses the same β-barrel/vesicle mechanism as SARS-CoV-2 untested","Direct interaction with Env not shown"]},{"year":2025,"claim":"Identified plasma-membrane ACE2 downregulation as one mechanism of SARS-CoV-2 entry restriction, adding a receptor-availability arm to the fusion-block model.","evidence":"ISG-KO screen, PLSCR1 KO/overexpression and surface ACE2 flow cytometry with authentic virus","pmids":["39945535"],"confidence":"Medium","gaps":["Mechanism of selective surface ACE2 removal not defined","Reconciliation with vesicle-targeting model not addressed"]},{"year":2025,"claim":"Defined NEDD4-2 as the ubiquitin ligase controlling PLSCR1 protein stability, with functional consequences for phosphatidylserine exposure and apoptotic-cell clearance.","evidence":"AP-MS, co-IP, ubiquitination assay, NEDD4-2 KO cells/mouse kidney and macrophage clearance assays","pmids":["40835608"],"confidence":"Medium","gaps":["Ubiquitination sites on PLSCR1 not mapped","Whether degradation regulates antiviral activity untested"]},{"year":2025,"claim":"United PLSCR1's transcriptional and antiviral roles by showing it both activates IFNLR1 transcription and binds IFN-λR1 protein to modulate interferon-lambda signaling against influenza, with dual genetic mouse models.","evidence":"ChIP, co-IP, Plscr1-/- and Foxj1-Cre+ overexpressor mice, transcriptomics and scRNA-seq","pmids":["41439508"],"confidence":"High","gaps":["How nuclear (transcriptional) and surface (receptor-binding) functions are partitioned not resolved","Lipid scramblase activity shown dispensable but the active determinant not localized"]},{"year":2026,"claim":"Implicated PLSCR1 in chemoresistance through EGFR binding and MAPK-driven efflux-pump upregulation, with m6A-mediated stabilization of its own mRNA.","evidence":"Co-IP, siRNA, m6A analysis and in vitro/in vivo assays in chemoresistant TNBC","pmids":["42140933"],"confidence":"Medium","gaps":["Direct vs. indirect EGFR activation not distinguished","Relationship to nuclear transcriptional roles unclear"]},{"year":null,"claim":"How a single protein integrates its membrane fusion-blocking, lipid scramblase, and nuclear transcriptional activities—and what structural determinant of the β-barrel mediates broad antiviral fusion blockade—remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of PLSCR1 engaging a viral glycoprotein or vesicle","Switch logic between membrane and nuclear pools not unified","Physiological role of scramblase activity distinct from antiviral function undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[5,7,9,16,10]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[5,7,9,16]},{"term_id":"GO:0016853","term_label":"isomerase activity","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1,6,12,18]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3,5,7,8,9,14,16]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[12,1]}],"pathway":[{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[12,13,17,18,10,11]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[6,16,11]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[5,7,9,16,10]}],"complexes":["RELT-OSR1-PLSCR1 complex"],"partners":["RELT","RELL1","RELL2","OSR1","ILDR1","KPNA2","NEDD4L","EGFR"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O15162","full_name":"Phospholipid scramblase 1","aliases":["Ca(2+)-dependent phospholipid scramblase 1","Erythrocyte phospholipid scramblase","Mg(2+)-dependent nuclease","MmTRA1b"],"length_aa":318,"mass_kda":35.0,"function":"Catalyzes calcium-induced ATP-independent rapid bidirectional and non-specific movement of phospholipids (lipid scrambling or lipid flip-flop) between the inner and outer leaflet of the plasma membrane resulting in collapse of the phospholipid asymmetry which leads to phosphatidylserine externalization on the cell surface (PubMed:10770950, PubMed:18629440, PubMed:23590222, PubMed:23659204, PubMed:24343571, PubMed:24648509, PubMed:29748552, PubMed:32110987, PubMed:8663431, PubMed:9218461, PubMed:9485382, PubMed:9572851). Mediates calcium-dependent phosphatidylserine externalization and apoptosis in neurons via its association with TRPC5 (By similarity). Also exhibits magnesium-dependent nuclease activity against double-stranded DNA and RNA but not single-stranded DNA and can enhance DNA decatenation mediated by TOP2A (PubMed:17567603, PubMed:27206388). Negatively regulates FcR-mediated phagocytosis in differentiated macrophages (PubMed:26745724). May contribute to cytokine-regulated cell proliferation and differentiation (By similarity). May play a role in the antiviral response of interferon (IFN) by amplifying and enhancing the IFN response through increased expression of select subset of potent antiviral genes (PubMed:15308695). Inhibits the functions of viral transactivators, including human T-cell leukemia virus (HTLV)-1 protein Tax, human immunodeficiency virus (HIV)-1 Tat, human hepatitis B virus (HBV) HBx, Epstein-Barr virus (EBV) BZLF1 and human cytomegalovirus IE1 and IE2 proteins through direct interactions (PubMed:22789739, PubMed:23501106, PubMed:25365352, PubMed:31434743, PubMed:35138119). Also mediates the inhibition of influenza virus infection by preventing nuclear import of the viral nucleoprotein/NP (PubMed:29352288, PubMed:35595813). Plays a crucial role as a defense factor against SARS-CoV-2 independently of its scramblase activity by directly targeting nascent viral vesicles to prevent virus-membrane fusion and the release of viral RNA into the host-cell cytosol (PubMed:37438530) (Microbial infection) Acts as an attachment receptor for HCV","subcellular_location":"Cell membrane; Cell membrane; Nucleus; Cytoplasm; Cytoplasm, perinuclear region","url":"https://www.uniprot.org/uniprotkb/O15162/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PLSCR1","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PLSCR1","total_profiled":1310},"omim":[{"mim_id":"607612","title":"PHOSPHOLIPID SCRAMBLASE 4; PLSCR4","url":"https://www.omim.org/entry/607612"},{"mim_id":"607611","title":"PHOSPHOLIPID SCRAMBLASE 3; PLSCR3","url":"https://www.omim.org/entry/607611"},{"mim_id":"607610","title":"PHOSPHOLIPID SCRAMBLASE 2; PLSCR2","url":"https://www.omim.org/entry/607610"},{"mim_id":"604252","title":"BETA-SITE AMYLOID BETA A4 PRECURSOR PROTEIN-CLEAVING ENZYME 1; BACE1","url":"https://www.omim.org/entry/604252"},{"mim_id":"604170","title":"PHOSPHOLIPID SCRAMBLASE 1; PLSCR1","url":"https://www.omim.org/entry/604170"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Golgi apparatus","reliability":"Supported"},{"location":"Plasma membrane","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PLSCR1"},"hgnc":{"alias_symbol":["MMTRA1B"],"prev_symbol":[]},"alphafold":{"accession":"O15162","domains":[{"cath_id":"-","chopping":"109-306","consensus_level":"medium","plddt":82.0675,"start":109,"end":306}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O15162","model_url":"https://alphafold.ebi.ac.uk/files/AF-O15162-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O15162-F1-predicted_aligned_error_v6.png","plddt_mean":69.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PLSCR1","jax_strain_url":"https://www.jax.org/strain/search?query=PLSCR1"},"sequence":{"accession":"O15162","fasta_url":"https://rest.uniprot.org/uniprotkb/O15162.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O15162/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O15162"}},"corpus_meta":[{"pmid":"14766753","id":"PMC_14766753","title":"Phospholipid flip-flop and phospholipid scramblase 1 (PLSCR1) co-localize to uropod rafts in formylated Met-Leu-Phe-stimulated neutrophils.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14766753","citation_count":93,"is_preprint":false},{"pmid":"23487022","id":"PMC_23487022","title":"Wogonoside induces cell cycle arrest and differentiation by affecting expression and subcellular localization of PLSCR1 in AML cells.","date":"2013","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/23487022","citation_count":87,"is_preprint":false},{"pmid":"12605885","id":"PMC_12605885","title":"Spatial resolution of phospholipid scramblase 1 (PLSCR1), caspase-3 activation and DNA-fragmentation in the human hippocampus after cerebral ischemia.","date":"2003","source":"Neurochemistry international","url":"https://pubmed.ncbi.nlm.nih.gov/12605885","citation_count":58,"is_preprint":false},{"pmid":"16702944","id":"PMC_16702944","title":"Antileukemic roles of human phospholipid scramblase 1 gene, evidence from inducible PLSCR1-expressing leukemic cells.","date":"2006","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/16702944","citation_count":49,"is_preprint":false},{"pmid":"37438530","id":"PMC_37438530","title":"PLSCR1 is a cell-autonomous defence factor against SARS-CoV-2 infection.","date":"2023","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/37438530","citation_count":45,"is_preprint":false},{"pmid":"32292520","id":"PMC_32292520","title":"Nuclear translocation of PLSCR1 activates STAT1 signaling in basal-like breast cancer.","date":"2020","source":"Theranostics","url":"https://pubmed.ncbi.nlm.nih.gov/32292520","citation_count":37,"is_preprint":false},{"pmid":"9712717","id":"PMC_9712717","title":"Identity of human normal counterpart (MmTRA1b) of mouse leukemogenesis-associated gene (MmTRA1a) product as plasma membrane phospholipid scramblase and chromosome mapping of the human MmTRA1b/phospholipid scramblase gene.","date":"1998","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/9712717","citation_count":22,"is_preprint":false},{"pmid":"15863367","id":"PMC_15863367","title":"The phospholipid scramblase PLSCR1 increases UV induced apoptosis primarily through the augmentation of the intrinsic apoptotic pathway and independent of direct phosphorylation by protein kinase C delta.","date":"2005","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/15863367","citation_count":22,"is_preprint":false},{"pmid":"20926691","id":"PMC_20926691","title":"Pregnancy and interferon tau regulate DDX58 and PLSCR1 in the ovine uterus during the peri-implantation period.","date":"2010","source":"Reproduction (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/20926691","citation_count":19,"is_preprint":false},{"pmid":"28492556","id":"PMC_28492556","title":"PLSCR1/IP3R1/Ca2+ axis contributes to differentiation of primary AML cells induced by wogonoside.","date":"2017","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/28492556","citation_count":19,"is_preprint":false},{"pmid":"25658875","id":"PMC_25658875","title":"Induction of PLSCR1 in a STING/IRF3-dependent manner upon vector transfection in ovarian epithelial cells.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25658875","citation_count":19,"is_preprint":false},{"pmid":"35138119","id":"PMC_35138119","title":"The Interferon-Inducible Human PLSCR1 Protein Is a Restriction Factor of Human Cytomegalovirus.","date":"2022","source":"Microbiology spectrum","url":"https://pubmed.ncbi.nlm.nih.gov/35138119","citation_count":16,"is_preprint":false},{"pmid":"22052202","id":"PMC_22052202","title":"Identification of PLSCR1 as a protein that interacts with RELT family members.","date":"2011","source":"Molecular and cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22052202","citation_count":16,"is_preprint":false},{"pmid":"34773335","id":"PMC_34773335","title":"Nuclear accumulation of KPNA2 impacts radioresistance through positive regulation of the PLSCR1-STAT1 loop in lung adenocarcinoma.","date":"2021","source":"Cancer science","url":"https://pubmed.ncbi.nlm.nih.gov/34773335","citation_count":13,"is_preprint":false},{"pmid":"39316623","id":"PMC_39316623","title":"A genome-wide arrayed CRISPR screen identifies PLSCR1 as an intrinsic barrier to SARS-CoV-2 entry that recent virus variants have evolved to resist.","date":"2024","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/39316623","citation_count":12,"is_preprint":false},{"pmid":"29377576","id":"PMC_29377576","title":"Wogonoside induces depalmitoylation and translocation of PLSCR1 and N-RAS in primary acute myeloid leukaemia cells.","date":"2018","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/29377576","citation_count":10,"is_preprint":false},{"pmid":"35595813","id":"PMC_35595813","title":"ILDR1 promotes influenza A virus replication through binding to PLSCR1.","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/35595813","citation_count":10,"is_preprint":false},{"pmid":"25362260","id":"PMC_25362260","title":"Phospholipid scramblase 1 (PLSCR1) in villous trophoblast of the human placenta.","date":"2014","source":"Histochemistry and cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/25362260","citation_count":7,"is_preprint":false},{"pmid":"39945535","id":"PMC_39945535","title":"PLSCR1 suppresses SARS-CoV-2 infection by downregulating cell surface ACE2.","date":"2025","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/39945535","citation_count":2,"is_preprint":false},{"pmid":"34651249","id":"PMC_34651249","title":"The ratio of ATP11C/PLSCR1 mRNA transcripts has clinical significance in sickle cell anemia.","date":"2021","source":"Annals of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/34651249","citation_count":2,"is_preprint":false},{"pmid":"40835608","id":"PMC_40835608","title":"Phospholipid scramblase 1 (PLSCR1) is a novel substrate of NEDD4-2 (NEDD4L) mediated ubiquitination.","date":"2025","source":"Cell death discovery","url":"https://pubmed.ncbi.nlm.nih.gov/40835608","citation_count":2,"is_preprint":false},{"pmid":"39605457","id":"PMC_39605457","title":"Phospholipid Scramblase 1 (PLSCR1) Regulates Interferon-Lambda Receptor 1 (IFN-λR1) and IFN-λ Signaling in Influenza A Virus (IAV) Infection.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/39605457","citation_count":2,"is_preprint":false},{"pmid":"30004207","id":"PMC_30004207","title":"[Effect of PLSCR1 on the Antiviral Activity of IFN against HBV in HepG2 Cells].","date":"2016","source":"Bing du xue bao = Chinese journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/30004207","citation_count":2,"is_preprint":false},{"pmid":"26775483","id":"PMC_26775483","title":"[Significance of PLSCR1 in Matrine Induced Differentiation of ATRA Resistant APL Cells].","date":"2015","source":"Zhongguo Zhong xi yi jie he za zhi Zhongguo Zhongxiyi jiehe zazhi = Chinese journal of integrated traditional and Western medicine","url":"https://pubmed.ncbi.nlm.nih.gov/26775483","citation_count":2,"is_preprint":false},{"pmid":"41004226","id":"PMC_41004226","title":"IFN-inducible human phospholipid scramblase 1 (PLSCR1) protein restricts HIV-1 infection by inhibiting membrane fusion.","date":"2025","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/41004226","citation_count":1,"is_preprint":false},{"pmid":"41439508","id":"PMC_41439508","title":"Phospholipid scramblase 1 (PLSCR1) regulates interferon-lambda receptor 1 (IFN-λR1) and IFN-λ signaling in influenza A virus (IAV) infection.","date":"2025","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/41439508","citation_count":1,"is_preprint":false},{"pmid":"39312982","id":"PMC_39312982","title":"Transcriptome analysis unveils PLSCR1 associated with microglial polarization in neuropathic pain.","date":"2024","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/39312982","citation_count":1,"is_preprint":false},{"pmid":"41031002","id":"PMC_41031002","title":"IFN-inducible Human Phospholipid Scramblase 1 (PLSCR1) Protein Restricts HIV-1 Infection by Inhibiting Membrane Fusion.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/41031002","citation_count":0,"is_preprint":false},{"pmid":"42140933","id":"PMC_42140933","title":"PLSCR1 drives chemoresistance in TNBC via METTL3/IGF2BP3-mediated mRNA stabilization and EGFR-MAPK pathway activation.","date":"2026","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/42140933","citation_count":0,"is_preprint":false},{"pmid":"40445264","id":"PMC_40445264","title":"FOXA1 Transcriptional Repression of PLSCR1 Inhibits Tongue Squamous Cell Carcinoma Progression.","date":"2025","source":"Cell biochemistry and biophysics","url":"https://pubmed.ncbi.nlm.nih.gov/40445264","citation_count":0,"is_preprint":false},{"pmid":"41146421","id":"PMC_41146421","title":"PLSCR1 Regulates the Physiology of Fibroblast-Like Synoviocytes via Modulating the STAT1 Signaling Pathway.","date":"2025","source":"Immunity, inflammation and disease","url":"https://pubmed.ncbi.nlm.nih.gov/41146421","citation_count":0,"is_preprint":false},{"pmid":"37708846","id":"PMC_37708846","title":"Fortifying immunity: PLSCR1 picks battle against SARS-CoV-2.","date":"2023","source":"Cell host & microbe","url":"https://pubmed.ncbi.nlm.nih.gov/37708846","citation_count":0,"is_preprint":false},{"pmid":"41809104","id":"PMC_41809104","title":"Annurca apple polyphenols prevent mercury-induced phosphatidylserine externalization in human erythrocytes via calcium-dependent PLSCR1 regulation.","date":"2026","source":"Frontiers in nutrition","url":"https://pubmed.ncbi.nlm.nih.gov/41809104","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":20149,"output_tokens":5777,"usd":0.073551,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14398,"output_tokens":5403,"usd":0.103532,"stage2_stop_reason":"end_turn"},"total_usd":0.177083,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"Human PLSCR1 (MmTRA1b) was identified as the plasma membrane phospholipid scramblase required for transbilayer movement of membrane phospholipids; the predicted amino acid sequence showed perfect identity with the human plasma membrane phospholipid scramblase.\",\n      \"method\": \"cDNA cloning, sequence analysis, and expression studies in U937 cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — sequence identity established functional assignment, expression correlation during differentiation, single lab\",\n      \"pmids\": [\"9712717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PLSCR1 is present in plasma membranes of non-permeabilized neutrophils and is also located in secretory vesicles and tertiary and secondary granules; it is enriched in detergent-insoluble membranes (lipid rafts) and co-localizes with raft markers at the neutrophil uropod following fMLP stimulation. Phospholipid flip-flop activity (PS exposure and uptake) also localizes to this uropod domain. fMLP stimulation did not significantly alter PLSCR1 surface labeling, suggesting stimulated phospholipid flip-flop does not require additional mobilization of PLSCR1 to the plasma membrane.\",\n      \"method\": \"Flow cytometry with anti-PLSCR1 antibodies, subcellular fractionation, detergent-insoluble membrane isolation, live-cell fluorescent lipid uptake assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (flow cytometry, fractionation, lipid probes), single lab\",\n      \"pmids\": [\"14766753\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PLSCR1 augments UV-induced apoptosis primarily through the intrinsic (caspase-9) apoptotic pathway rather than the extrinsic (caspase-8) pathway. A PLSCR1 mutant with alanine substitution at the PKC-delta phosphorylation site enhanced UV-induced apoptosis to the same level as wild-type PLSCR1, indicating that direct phosphorylation of PLSCR1 by PKC-delta is not required for PLSCR1-enhanced scramblase activity during apoptosis.\",\n      \"method\": \"Caspase inhibitor pharmacology, site-directed mutagenesis (Ala substitution at PKC-delta phosphorylation site), transfection, apoptosis assays\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis plus pathway inhibitor experiments, single lab, two orthogonal approaches\",\n      \"pmids\": [\"15863367\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Inducible overexpression of PLSCR1 in U937 myeloid leukemic cells arrested proliferation at G1 phase and promoted granulocyte-like differentiation, increased CDK inhibitors p27(Kip1) and p21(Cip1), downregulated SKP2, decreased c-Myc and Bcl-2 proteins, and increased sensitivity to etoposide-induced apoptosis. PLSCR1 localization is regulated by its palmitoylation state, with palmitoylated PLSCR1 at the membrane and depalmitoylated form in the nucleus.\",\n      \"method\": \"Tetracycline-inducible expression system, flow cytometry (cell cycle), Western blotting\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — inducible expression with defined cellular phenotype and multiple molecular markers, single lab\",\n      \"pmids\": [\"16702944\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PLSCR1 physically interacts with all three RELT family members (RELT, RELL1, RELL2) as identified by yeast two-hybrid screening and confirmed by co-immunoprecipitation. OSR1 kinase phosphorylates PLSCR1 in vitro only in the presence of RELT, suggesting formation of a functional multiprotein RELT-OSR1-PLSCR1 complex. RELT overexpression alters the intracellular localization of PLSCR1.\",\n      \"method\": \"Yeast two-hybrid screen, co-immunoprecipitation, in vitro kinase assay, fluorescence co-localization\",\n      \"journal\": \"Molecular and cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus reciprocal Co-IP plus in vitro kinase assay, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"22052202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Wogonoside promotes PLSCR1 nuclear translocation in AML cells, where nuclear PLSCR1 binds to the IP3R1 promoter and increases IP3R1 expression; PLSCR1 knockdown partially blocked wogonoside-induced G1 cell cycle arrest and differentiation.\",\n      \"method\": \"siRNA knockdown, ChIP, immunostaining, Western blotting, flow cytometry\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP demonstrating promoter binding, siRNA rescue experiments, multiple orthogonal methods, single lab\",\n      \"pmids\": [\"23487022\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PLSCR1 induction by dsDNA transfection in ovarian epithelial cells is mediated by the STING/IRF3 pathway: IRF3 siRNA knockdown or STING siRNA knockdown markedly reduced PLSCR1 protein induction, while MAPK inhibition had no effect. De novo synthesized PLSCR1 localized predominantly to the plasma membrane.\",\n      \"method\": \"siRNA knockdown of STING and IRF3, kinase inhibitor (U0126), Western blotting, immunofluorescence\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA epistasis for two pathway components with localization data, single lab, two orthogonal knockdown experiments\",\n      \"pmids\": [\"25658875\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Nuclear PLSCR1 binds the IP3R1 promoter in primary AML cells, leading to IP3R1 upregulation, release of Ca2+ from the endoplasmic reticulum, and AML cell differentiation; this PLSCR1/IP3R1/Ca2+ axis mediates wogonoside's anti-leukemic effects.\",\n      \"method\": \"ChIP, Ca2+ flux measurements, in vivo xenograft (NOD/SCID mice), Western blotting\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP, Ca2+ measurements, in vivo validation, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"28492556\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Nuclear translocation of PLSCR1 in primary AML cells is dependent on depalmitoylation mediated by acyl protein thioesterase 1 (APT-1); wogonoside induces APT-1-mediated depalmitoylation of PLSCR1, enabling its nuclear trafficking.\",\n      \"method\": \"Depalmitoylation assay, inhibitor studies, Western blotting, immunofluorescence\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — biochemical depalmitoylation assay with APT-1 connection and localization data, single lab\",\n      \"pmids\": [\"29377576\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Phosphorylation of PLSCR1 at Tyr69/74 drives its nuclear translocation in basal-like breast cancer cells. Nuclear PLSCR1 is enriched at the STAT1 promoter and enhances STAT3 binding to the STAT1 promoter, leading to STAT1 transactivation, which promotes cancer stem cell properties and BLBC progression.\",\n      \"method\": \"Immunostaining, co-IP, ChIP, quantitative RT-PCR, siRNA knockdown, in vitro and in vivo tumorigenesis assays\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP, Co-IP, and functional rescue with multiple orthogonal methods, single lab\",\n      \"pmids\": [\"32292520\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PLSCR1 restricts human cytomegalovirus (HCMV) replication by repressing transcription from viral major immediate early (MIE) and early promoters; PLSCR1 expression reduced levels of CREB•IE2 and CBP•IE2 complexes important for viral early promoter transactivation. PLSCR1-KO cells showed significantly increased HCMV plaque formation and MIE gene expression.\",\n      \"method\": \"PLSCR1-knockout cell lines, reporter gene assays (CRE- and MIE promoter-driven), co-immunoprecipitation, plaque assay\",\n      \"journal\": \"Microbiology spectrum\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO cells plus reporter assays plus Co-IP, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"35138119\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ILDR1 was identified as a novel PLSCR1-binding partner by yeast two-hybrid screening; ILDR1 competes with influenza A virus NP protein for binding to PLSCR1, disrupting the antiviral PLSCR1-NP interaction. Plscr1-/- mice are more susceptible to H1N1 infection. The PLSCR1-ILDR1-NP regulatory pathway limits IAV infection.\",\n      \"method\": \"Yeast two-hybrid screening, co-immunoprecipitation, Plscr1-/- mouse infection model\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus Co-IP plus in vivo knockout model, single lab\",\n      \"pmids\": [\"35595813\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PLSCR1 is a potent cell-autonomous restriction factor against SARS-CoV-2 identified by parallel genome-wide CRISPR-Cas9 screens in human lung epithelia and hepatocytes. IFNγ-induced PLSCR1 interferes with both endocytic and TMPRSS2-dependent fusion entry routes. Whole-cell 4Pi nanoscopy and bipartite nano-reporter assays showed PLSCR1 targets SARS-CoV-2-containing vesicles to prevent spike-mediated fusion and viral escape. The C-terminal β-barrel domain—but not lipid scramblase enzymatic activity—is essential for this fusogenic blockade.\",\n      \"method\": \"Genome-wide CRISPR-Cas9 screens, 4Pi single-molecule switching nanoscopy, bipartite nano-reporter fusion assays, domain mutagenesis, multiple viral lineage testing, bat and mouse functional conservation studies\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — parallel CRISPR screens, nanoscopy, fusion reporter assays, domain mutagenesis, multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"37438530\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Genome-wide arrayed CRISPR knockout screen confirmed PLSCR1 as an IFN-stimulated gene that restricts spike-mediated SARS-CoV-2 entry specifically via the endocytic route; TMPRSS2 overexpression alleviated PLSCR1-mediated restriction. PLSCR1 did not contribute to IFN signaling per se but restricted viral entry. Recent SARS-CoV-2 variants have adapted to circumvent PLSCR1 restriction.\",\n      \"method\": \"Genome-wide arrayed CRISPR knockout screen, TMPRSS2 overexpression epistasis, integrated analysis of 67 large-scale studies\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — arrayed genome-wide CRISPR screen with epistasis experiments, replicated independently of Xu et al. 2023\",\n      \"pmids\": [\"39316623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"KPNA2 (importin α2) interacts with endogenous PLSCR1 and mediates its nuclear accumulation in radioresistant lung adenocarcinoma cells; PLSCR1 knockdown suppressed KPNA2-induced radioresistance. A positive feedback loop between nuclear PLSCR1 and STAT1 modulates cancer stem cell characteristics and radioresistance.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, next-generation sequencing, functional radioresistance assays\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus siRNA functional rescue, single lab, two orthogonal methods\",\n      \"pmids\": [\"34773335\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"NEDD4-2 (NEDD4L) ubiquitin ligase directly interacts with and ubiquitinates PLSCR1, regulating its protein stability. NEDD4-2 deficiency in cells and mouse kidney increased PLSCR1 protein levels, enhanced phosphatidylserine exposure in response to calcium and apoptotic stimuli, and increased macrophage clearance of apoptotic cells.\",\n      \"method\": \"Affinity purification mass spectrometry, co-immunoprecipitation, ubiquitination assay, NEDD4-2 KO cells and mouse kidney model, annexin V/flow cytometry, macrophage clearance assay\",\n      \"journal\": \"Cell death discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — AP-MS plus Co-IP plus KO model with functional readout, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"40835608\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PLSCR1 acts as a transcriptional activator of IFN-λR1 (IFNLR1) by directly binding to its promoter after IAV infection, and also interacts with IFN-λR1 protein on the cell surface of pulmonary epithelial cells to modulate IFN-λ signaling. Plscr1-/- mice show impaired Ifn-λr1 and downstream ISG expression upon IAV infection. The lipid scramblase enzymatic activity of PLSCR1 is dispensable for its anti-influenza activity.\",\n      \"method\": \"ChIP (promoter binding), co-immunoprecipitation (IFN-λR1 interaction), Plscr1-/- mouse model, Plscr1-overexpressing (Foxj1-Cre+) mice, transcriptomic analysis, single-cell RNA sequencing\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP plus Co-IP plus two independent genetic mouse models (KO and overexpressor) with functional readouts, multiple orthogonal methods in one study\",\n      \"pmids\": [\"41439508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PLSCR1 restricts HIV-1 entry by blocking virion-cell and cell-cell membrane fusion mediated by the HIV-1 envelope glycoprotein (Env), without affecting CD4 or CXCR4 surface expression or virus binding to cells. This restriction is broad-spectrum (HIV-1 diverse tropisms/subtypes, HIV-2, SIV) and independent of type I IFN signaling.\",\n      \"method\": \"Multiple cell types (SupT1, purified CD4+ T cells), fusion assays, cell-to-cell transmission assays, receptor expression analysis, viral replication assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple cell types and virus strains with direct fusion assays, single lab\",\n      \"pmids\": [\"41004226\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PLSCR1 inhibits SARS-CoV-2 entry by specifically downregulating plasma membrane expression of ACE2 (the viral receptor) without affecting total cellular ACE2 levels. PLSCR1 KO cells showed enhanced cellular entry of both pseudotyped and authentic SARS-CoV-2.\",\n      \"method\": \"109 ISG-knockout cell lines screen, PLSCR1 KO and overexpression, pseudotyped and authentic virus entry assays, flow cytometry for surface ACE2\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO plus overexpression with direct surface receptor quantification, single lab, two orthogonal entry assays\",\n      \"pmids\": [\"39945535\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"PLSCR1 interacts with EGFR and promotes its phosphorylation and activation of the MAPK signaling pathway in chemoresistant TNBC cells, leading to upregulation of efflux pumps P-gp and MRP1. Concurrently, PLSCR1 mRNA is stabilized via METTL3-mediated m6A modification recognized by the m6A reader IGF2BP3.\",\n      \"method\": \"Co-immunoprecipitation (PLSCR1-EGFR), siRNA knockdown, Western blotting, in vitro and in vivo functional assays, m6A modification analysis\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus KD functional rescue plus m6A analysis, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"42140933\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"FOXA1 transcriptionally represses PLSCR1 by binding to the PLSCR1 promoter in tongue squamous cell carcinoma cells, as demonstrated by ChIP and dual-luciferase assays; PLSCR1 knockdown inhibited TSCC cell proliferation, migration, and invasion, while FOXA1 overexpression inhibited TSCC progression in a PLSCR1-dependent manner.\",\n      \"method\": \"ChIP, dual-luciferase reporter assay, siRNA knockdown, lentiviral overexpression, xenograft mouse model\",\n      \"journal\": \"Cell biochemistry and biophysics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus reporter assay plus rescue experiments, single lab\",\n      \"pmids\": [\"40445264\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PLSCR1 regulates the proliferation, apoptosis, and inflammatory cytokine production (TNF-α, IL-1β, IL-6) of fibroblast-like synoviocytes by modulating STAT1 signaling; STAT1 activation rescued the effects of PLSCR1 knockdown, placing PLSCR1 upstream of STAT1 in this pathway.\",\n      \"method\": \"siRNA knockdown, STAT1 activator rescue (2-NP), EdU proliferation assay, flow cytometry (apoptosis), ELISA (cytokines)\",\n      \"journal\": \"Immunity, inflammation and disease\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — siRNA plus pharmacological rescue, single lab, single method per readout\",\n      \"pmids\": [\"41146421\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PLSCR1 is an interferon-inducible, multiply palmitoylated plasma membrane protein that functions as a cell-autonomous antiviral restriction factor (against SARS-CoV-2, HIV-1, HCMV, and influenza A virus) by blocking spike/Env-mediated membrane fusion and viral entry—via its C-terminal β-barrel domain rather than lipid scramblase enzymatic activity—while also trafficking to the nucleus upon depalmitoylation (mediated by APT-1) or Tyr69/74 phosphorylation, where it binds gene promoters (IP3R1, STAT1, IFN-λR1) to regulate transcription; its protein stability is controlled by NEDD4-2-mediated ubiquitination, it participates in multiprotein complexes with RELT family members and OSR1, and it interacts with EGFR to activate MAPK signaling in cancer cells.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PLSCR1 is an interferon-stimulated, palmitoylation-regulated plasma membrane protein that acts as a broad cell-autonomous antiviral restriction factor and a stimulus-dependent nuclear transcriptional regulator [#12, #5]. As a restriction factor it blocks enveloped-virus entry by interfering with glycoprotein-mediated membrane fusion: parallel genome-wide CRISPR screens established it as a potent SARS-CoV-2 restriction factor that targets virus-containing vesicles to prevent spike-mediated fusion through its C-terminal \\u03b2-barrel domain rather than its lipid scramblase activity [#12], a route-specific blockade of endocytic entry that is overcome by TMPRSS2 and circumvented by recent variants [#13], and in part reflects downregulation of plasma-membrane ACE2 [#18]. The same fusion-blocking activity, independent of lipid scramblase function and of type I IFN signaling, restricts HIV-1 Env-mediated fusion [#17] and influenza A virus, where PLSCR1 binds the viral NP protein in a manner competed by ILDR1 [#11]; PLSCR1 additionally restricts HCMV by repressing transcription from viral immediate-early and early promoters [#10]. Beyond direct restriction, PLSCR1 traffics to the nucleus following APT-1\\u2013mediated depalmitoylation [#8] or Tyr69/74 phosphorylation [#9] and binds gene promoters to drive transcription of IP3R1 [#5, #7], STAT1 [#9], and the IFN-\\u03bb receptor IFNLR1 [#16], coupling it to calcium signaling, myeloid differentiation, and interferon responses. Its abundance is controlled by NEDD4-2\\u2013mediated ubiquitination [#15], and it nucleates a RELT\\u2013OSR1\\u2013PLSCR1 multiprotein complex in which OSR1 phosphorylates PLSCR1 only in the presence of RELT [#4]. In cancer, nuclear PLSCR1 promotes stem-cell properties and radioresistance via a STAT1 feedback loop [#9, #14] and engages EGFR to activate MAPK signaling and drug efflux [#19].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established the founding biochemical identity of PLSCR1 as the plasma membrane phospholipid scramblase mediating transbilayer phospholipid movement, anchoring all subsequent functional work.\",\n      \"evidence\": \"cDNA cloning and sequence analysis with expression studies in U937 cells\",\n      \"pmids\": [\"9712717\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional assignment rested on sequence identity rather than reconstituted enzymatic assay\", \"No structural basis for scramblase activity defined\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Localized PLSCR1 and its lipid flip-flop activity to lipid-raft membrane domains at the stimulated neutrophil uropod, showing scramblase activity does not require new mobilization of the protein to the membrane.\",\n      \"evidence\": \"Flow cytometry, subcellular fractionation, and live-cell lipid uptake assays in neutrophils\",\n      \"pmids\": [\"14766753\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not resolve how flip-flop activity is triggered locally\", \"Single cell type\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Linked PLSCR1 to myeloid growth control and revealed that its palmitoylation state governs partitioning between membrane and nucleus, foreshadowing a dual-compartment function.\",\n      \"evidence\": \"Tetracycline-inducible overexpression in U937 cells with cell-cycle and apoptosis markers\",\n      \"pmids\": [\"16702944\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting nuclear PLSCR1 to gene-expression changes not yet defined\", \"Enzyme controlling palmitoylation cycle unidentified at this stage\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined PLSCR1 as a scaffold in a RELT-OSR1 signaling complex where RELT is required for OSR1-mediated phosphorylation of PLSCR1, connecting it to kinase signaling.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal co-IP, in vitro kinase assay, and co-localization\",\n      \"pmids\": [\"22052202\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of RELT-OSR1-PLSCR1 phosphorylation not established\", \"Phosphosite not mapped\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified APT-1-mediated depalmitoylation as the molecular switch enabling PLSCR1 nuclear translocation, explaining the membrane-to-nucleus relocation observed earlier.\",\n      \"evidence\": \"Depalmitoylation assays, inhibitor studies and immunofluorescence in primary AML cells\",\n      \"pmids\": [\"29377576\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether other stimuli use the same APT-1 switch unknown\", \"Nuclear import machinery not defined here\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Resolved the nuclear function of PLSCR1 as direct transcriptional activation of IP3R1, coupling it to ER calcium release and leukemic-cell differentiation.\",\n      \"evidence\": \"ChIP, Ca2+ flux measurements, and NOD/SCID xenografts (extends siRNA/ChIP work from 2013)\",\n      \"pmids\": [\"28492556\", \"23487022\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"DNA sequence recognized by PLSCR1 not defined\", \"Whether PLSCR1 binds DNA directly or via partners unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed Tyr69/74 phosphorylation as an alternative trigger for nuclear translocation and identified a nuclear PLSCR1-STAT3-STAT1 promoter axis driving cancer stemness, generalizing the transcriptional role beyond IP3R1.\",\n      \"evidence\": \"ChIP, co-IP, RT-PCR, siRNA, and in vivo tumorigenesis in basal-like breast cancer\",\n      \"pmids\": [\"32292520\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Kinase phosphorylating Tyr69/74 not identified\", \"Relationship between phosphorylation and depalmitoylation switches unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified KPNA2 as the import factor mediating PLSCR1 nuclear accumulation and placed a nuclear PLSCR1-STAT1 feedback loop in radioresistance.\",\n      \"evidence\": \"Co-IP, siRNA, NGS, and radioresistance assays in lung adenocarcinoma\",\n      \"pmids\": [\"34773335\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How depalmitoylation/phosphorylation feeds into KPNA2 recognition not shown\", \"Direct nuclear localization signal not mapped\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Extended PLSCR1 from a scramblase to an antiviral factor, demonstrating transcriptional repression of HCMV immediate-early/early promoters and disruption of CREB/CBP-IE2 complexes.\",\n      \"evidence\": \"PLSCR1-KO cells, reporter assays, co-IP and plaque assays\",\n      \"pmids\": [\"35138119\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether nuclear or membrane PLSCR1 mediates HCMV restriction unclear\", \"Direct DNA binding to viral promoters not shown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined a PLSCR1-NP antiviral interaction against influenza A and identified ILDR1 as a competing binding partner, with in vivo confirmation in Plscr1-/- mice.\",\n      \"evidence\": \"Yeast two-hybrid, co-IP, and Plscr1-/- mouse H1N1 infection\",\n      \"pmids\": [\"35595813\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Domain mediating NP binding not mapped\", \"Physiological trigger regulating ILDR1 competition unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Established PLSCR1 as a potent IFN-induced cell-autonomous SARS-CoV-2 restriction factor that blocks spike-mediated fusion at virus-containing vesicles via its C-terminal \\u03b2-barrel, decoupling restriction from lipid scramblase activity.\",\n      \"evidence\": \"Genome-wide CRISPR screens, 4Pi nanoscopy, fusion reporter assays and domain mutagenesis\",\n      \"pmids\": [\"37438530\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which the \\u03b2-barrel blocks fusion not fully resolved\", \"Host/viral binding partner at the vesicle not identified\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Independently confirmed PLSCR1 as an ISG restricting SARS-CoV-2 entry specifically via the endocytic route and showed TMPRSS2 bypass and variant adaptation, refining the restriction model.\",\n      \"evidence\": \"Arrayed genome-wide CRISPR screen with TMPRSS2 epistasis and meta-analysis\",\n      \"pmids\": [\"39316623\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Viral determinants of variant escape not defined\", \"Why restriction is endocytic-route specific not mechanistically explained\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Generalized the entry-blocking activity to HIV-1, SIV and HIV-2, showing PLSCR1 blocks Env-mediated fusion without affecting receptor expression or binding, IFN-independently.\",\n      \"evidence\": \"Fusion and cell-to-cell transmission assays across multiple cell types and viral strains\",\n      \"pmids\": [\"41004226\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether HIV-1 restriction uses the same \\u03b2-barrel/vesicle mechanism as SARS-CoV-2 untested\", \"Direct interaction with Env not shown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified plasma-membrane ACE2 downregulation as one mechanism of SARS-CoV-2 entry restriction, adding a receptor-availability arm to the fusion-block model.\",\n      \"evidence\": \"ISG-KO screen, PLSCR1 KO/overexpression and surface ACE2 flow cytometry with authentic virus\",\n      \"pmids\": [\"39945535\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of selective surface ACE2 removal not defined\", \"Reconciliation with vesicle-targeting model not addressed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined NEDD4-2 as the ubiquitin ligase controlling PLSCR1 protein stability, with functional consequences for phosphatidylserine exposure and apoptotic-cell clearance.\",\n      \"evidence\": \"AP-MS, co-IP, ubiquitination assay, NEDD4-2 KO cells/mouse kidney and macrophage clearance assays\",\n      \"pmids\": [\"40835608\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ubiquitination sites on PLSCR1 not mapped\", \"Whether degradation regulates antiviral activity untested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"United PLSCR1's transcriptional and antiviral roles by showing it both activates IFNLR1 transcription and binds IFN-\\u03bbR1 protein to modulate interferon-lambda signaling against influenza, with dual genetic mouse models.\",\n      \"evidence\": \"ChIP, co-IP, Plscr1-/- and Foxj1-Cre+ overexpressor mice, transcriptomics and scRNA-seq\",\n      \"pmids\": [\"41439508\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How nuclear (transcriptional) and surface (receptor-binding) functions are partitioned not resolved\", \"Lipid scramblase activity shown dispensable but the active determinant not localized\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Implicated PLSCR1 in chemoresistance through EGFR binding and MAPK-driven efflux-pump upregulation, with m6A-mediated stabilization of its own mRNA.\",\n      \"evidence\": \"Co-IP, siRNA, m6A analysis and in vitro/in vivo assays in chemoresistant TNBC\",\n      \"pmids\": [\"42140933\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs. indirect EGFR activation not distinguished\", \"Relationship to nuclear transcriptional roles unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single protein integrates its membrane fusion-blocking, lipid scramblase, and nuclear transcriptional activities\\u2014and what structural determinant of the \\u03b2-barrel mediates broad antiviral fusion blockade\\u2014remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of PLSCR1 engaging a viral glycoprotein or vesicle\", \"Switch logic between membrane and nuclear pools not unified\", \"Physiological role of scramblase activity distinct from antiviral function undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [5, 7, 9, 16, 10]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [5, 7, 9, 16]},\n      {\"term_id\": \"GO:0016853\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1, 6, 12, 18]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3, 5, 7, 8, 9, 14, 16]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [12, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [12, 13, 17, 18, 10, 11]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [6, 16, 11]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [5, 7, 9, 16, 10]}\n    ],\n    \"complexes\": [\n      \"RELT-OSR1-PLSCR1 complex\"\n    ],\n    \"partners\": [\n      \"RELT\",\n      \"RELL1\",\n      \"RELL2\",\n      \"OSR1\",\n      \"ILDR1\",\n      \"KPNA2\",\n      \"NEDD4L\",\n      \"EGFR\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}