{"gene":"PDCD4","run_date":"2026-04-29T11:37:58","timeline":{"discoveries":[{"year":1999,"finding":"PDCD4 protein inhibits tumor promoter-induced neoplastic transformation; antisense-mediated reduction of PDCD4 in promotion-resistant (P-) mouse JB6 cells converts them to a transformation-sensitive (P+) phenotype, and re-expression of PDCD4 sense fragment restores the P- phenotype, establishing PDCD4 as a direct suppressor of neoplastic transformation.","method":"Antisense stable cell lines, phenotypic reversion by sense re-expression, mRNA differential display","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — clean loss-of-function with defined phenotypic readout plus gain-of-function rescue, replicated in multiple cell lines","pmids":["10570194"],"is_preprint":false},{"year":2004,"finding":"PDCD4 suppresses AP-1-driven transcription by interacting directly with c-Jun, blocking JNK-mediated phosphorylation of c-Jun and preventing recruitment of the co-activator p300 to c-Jun.","method":"Luciferase reporter assays, co-immunoprecipitation, in vitro kinase assays","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 — reciprocal protein interaction with functional reporter assay and mechanistic epistasis, multiple orthogonal methods in single paper","pmids":["15334056"],"is_preprint":false},{"year":2005,"finding":"Akt phosphorylates PDCD4 at Ser67 and Ser457 in vitro and in vivo, and this phosphorylation causes nuclear translocation of PDCD4 and significantly reduces its ability to suppress AP-1-dependent transcription driven by c-Jun.","method":"In vitro kinase assay, site-directed mutagenesis, luciferase reporter assay, subcellular fractionation/imaging","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinase assay with mutagenesis plus in vivo validation and functional reporter readout","pmids":["16357133"],"is_preprint":false},{"year":2008,"finding":"Tumor promoter TPA triggers proteasomal degradation of PDCD4 via a PKC-PI3K-Akt-mTOR-p70S6K and MEK-ERK signaling cascade; Akt and p70S6K phosphorylate PDCD4, enabling binding of the E3-ubiquitin ligase β-TrCP and subsequent ubiquitylation and proteasomal degradation. Pdcd4-heterozygous mice show increased tumor formation, establishing PDCD4 as a haploinsufficient tumor suppressor.","method":"In vitro ubiquitination assay, pharmacological inhibitors, Pdcd4-knockout/heterozygous mouse tumor model, Western blot","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 1 — biochemical reconstitution of ubiquitination pathway plus in vivo genetic evidence, multiple methods","pmids":["18296647"],"is_preprint":false},{"year":2009,"finding":"Crystal structure of human eIF4A–PDCD4 complex reveals that one PDCD4 molecule binds two eIF4A molecules through two distinct modes: both MA3 domains of PDCD4 bind one eIF4A, while the C-terminal MA3 domain alone contacts a second eIF4A. PDCD4 MA3 domains bind perpendicular to the eIF4A interdomain interface, preventing domain closure of eIF4A and blocking RNA binding, thereby inhibiting eIF4A helicase activity.","method":"X-ray crystallography, biochemical binding assays, mutagenesis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — crystal structure with biochemical validation and mutagenesis in single study","pmids":["19204291"],"is_preprint":false},{"year":2011,"finding":"PDCD4 is associated with p53 mRNA and suppresses its translation via the structured 5'-UTR of p53 mRNA in an eIF4A-interaction-dependent manner. DNA-damaging agents decrease PDCD4 levels, thereby releasing translational suppression of p53.","method":"RNA immunoprecipitation, reporter assay with 5'-UTR constructs, eIF4A-binding mutants, Western blot","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — direct RNA association demonstrated with eIF4A-binding mutant controls and 5'-UTR reporter dissection","pmids":["22033922"],"is_preprint":false},{"year":2011,"finding":"Decorin acts as an endogenous ligand of TLR2 and TLR4 and stimulates PDCD4 production in macrophages; decorin also reduces miR-21 abundance (which normally suppresses PDCD4 translation), thereby increasing PDCD4 levels. Elevated PDCD4 in turn decreases IL-10 release, shifting the cytokine profile toward a proinflammatory state.","method":"TLR2/4 signaling assays, miR-21 quantification, PDCD4 protein measurement, IL-10 ELISA, sepsis and xenograft mouse models","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 2 — two independent mechanisms demonstrated with in vivo validation in multiple models","pmids":["22087031"],"is_preprint":false},{"year":2012,"finding":"p70S6K1 phosphorylates PDCD4, and this phosphorylation (along with eIF4B phosphorylation) is required for mTORC1-mediated promotion of global protein synthesis; maintenance of eIF4E–eIF4G interaction alone is insufficient without p70S6K1 signaling to PDCD4.","method":"Genetic knockout of 4E-BP1/2, rapamycin treatment, polysome profiling, Western blot in MEFs and rat liver","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — epistasis in multiple genetic backgrounds with functional translation readout","pmids":["23105104"],"is_preprint":false},{"year":2008,"finding":"PDCD4 knockdown in HeLa cells increases expression of p21(Waf1/Cip1) and other p53-regulated genes, and PDCD4 interferes with p53-responsive promoter activation by p53. Pdcd4 knockdown cells show decreased apoptosis and increased survival after UV irradiation, implicating PDCD4 in the DNA-damage response.","method":"Stable shRNA knockdown, reporter gene assay, UV survival assay, Western blot","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 — clean stable KD with defined transcriptional and apoptotic phenotypes plus reporter mechanistic follow-up","pmids":["18427550"],"is_preprint":false},{"year":2014,"finding":"PDCD4 directly interacts with NF-κB p65 protein (co-immunoprecipitation and confocal co-localization) in glioblastoma cells, inhibiting nuclear localization of p65 (but not p50) and suppressing NF-κB-dependent transcription independently of upstream IKK or IκBα degradation.","method":"Co-immunoprecipitation, confocal imaging, luciferase reporter assay, stable PDCD4 overexpression, qPCR of NF-κB target genes","journal":"Carcinogenesis","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP with functional reporter and subcellular localization data, orthogonal methods","pmids":["24413684"],"is_preprint":false},{"year":2014,"finding":"In macrophages, PDCD4 and transcription factor Twist2 form a complex in unstimulated cells. LPS induces PI3K/mTOR-dependent degradation of PDCD4, releasing Twist2, which then binds the c-Maf promoter to drive IL-10 production.","method":"Co-immunoprecipitation, ChIP (Twist2 at c-Maf promoter), PI3K/mTOR pharmacological inhibitors, PDCD4 knockdown, ELISA for IL-10","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — protein complex identified by Co-IP, ChIP validates downstream transcription, inhibitors confirm pathway order","pmids":["24982420"],"is_preprint":false},{"year":2015,"finding":"IBtkα forms a CRL3(IBTK) ubiquitin ligase complex and promotes ubiquitylation and proteasomal degradation of PDCD4; serum-induced degradation of PDCD4 requires both IBtkα and Cul3. IBtkα-mediated PDCD4 degradation counteracts PDCD4-dependent translational repression, including of Bcl-xL mRNA.","method":"Affinity purification, co-immunoprecipitation, in vitro ubiquitination assay, RNAi knockdown, luciferase reporter assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro ubiquitination assay with multiple orthogonal methods and functional translation readout","pmids":["25882842"],"is_preprint":false},{"year":2017,"finding":"PDCD4 inhibits Sin1 (mTORC2 component) translation via suppression of eIF4A, using the SIN1 5'-UTR as the regulatory element. PDCD4 mutants that cannot bind eIF4A fail to repress Sin1 translation, and loss of Pdcd4 increases mTORC2 kinase activity and Snail expression, promoting colon tumor cell invasion.","method":"5'-UTR luciferase reporter assay, PDCD4 deletion/point mutants (D253A/D418A eIF4A-binding mutant), siRNA knockdown, eIF4A inhibitor silvestrol, invasion assays, patient tissue analysis","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1 — mechanistic dissection with eIF4A-binding mutants, reporter assay, pharmacological inhibition, and in vivo correlate","pmids":["28692058"],"is_preprint":false},{"year":2019,"finding":"DTL (a CUL4-DDB1 E3 ligase adaptor) interacts with PDCD4, promotes its ubiquitination, and accelerates its proteasomal degradation, thereby enhancing cancer cell proliferation and migration that are rescued by PDCD4 re-expression.","method":"Affinity-purification mass spectrometry, co-immunoprecipitation, in vitro ubiquitination assay, immunofluorescence, stable overexpression/knockdown lines, rescue experiment","journal":"Journal of experimental & clinical cancer research","confidence":"High","confidence_rationale":"Tier 1 — in vitro ubiquitination assay with Co-IP and functional rescue experiment","pmids":["31409387"],"is_preprint":false},{"year":2019,"finding":"SKP2 (SCF E3 ligase) promotes PDCD4 phosphorylation, ubiquitination, and proteasomal degradation. SKP2 knockdown increases PDCD4, reduces proliferation, and enhances apoptosis; these effects are reversed by simultaneous PDCD4 knockdown, placing SKP2-mediated PDCD4 degradation upstream of its tumor-suppressive function in breast cancer.","method":"Mass spectrometry, reciprocal Co-IP, in vitro ubiquitination, stable overexpression/knockdown, xenograft model","journal":"Journal of experimental & clinical cancer research","confidence":"High","confidence_rationale":"Tier 1 — in vitro ubiquitination with reciprocal Co-IP and in vivo rescue","pmids":["30760284"],"is_preprint":false},{"year":2012,"finding":"PDCD4 knockdown in Pdcd4-deficient mice promotes colitis-associated colorectal cancer by upregulating IL-6 expression and enhancing IL-6/STAT3 pathway activation; blockade of IL-6/STAT3 with sgp130Fc reverses the pro-proliferative effect of PDCD4 deficiency in vivo.","method":"Pdcd4 knockout mice, DSS/AOM colitis-cancer model, cytokine ELISA, Western blot for STAT3 signaling, BrdU incorporation, sgp130Fc rescue","journal":"Inflammatory bowel diseases","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with defined in vivo pathway rescue, multiple phenotypic readouts","pmids":["26891257"],"is_preprint":false},{"year":2001,"finding":"The chicken Pdcd4 gene is a direct transcriptional target of the retroviral oncogene v-Myb; v-Myb regulates Pdcd4 expression in myelomonocytic cells, providing the first evidence that a myb transcription factor directly controls Pdcd4 expression.","method":"Differential display, inducible v-Myb expression system, promoter analysis","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 — direct regulatory relationship shown in avian ortholog with inducible expression system, single lab","pmids":["11313950"],"is_preprint":false},{"year":2012,"finding":"PDCD4 knockdown increases MAP4K1 expression through upregulation of c-Myc, which directly binds the MAP4K1 promoter (demonstrated by ChIP), leading to enhanced JNK phosphorylation of c-Jun and AP-1-dependent transcription; dominant-negative Tcf4 reduces c-Myc and MAP4K1, connecting β-catenin/Tcf signaling to this pathway.","method":"ChIP, promoter-luciferase reporter with mutational analysis, siRNA, dominant-negative Tcf4, Western blot","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 2 — ChIP validates direct binding, multiple orthogonal approaches in single study","pmids":["22801218"],"is_preprint":false},{"year":2020,"finding":"During mitotic arrest, mTORC1 activity is reduced due to raptor phosphorylation; this allows PDCD4 accumulation (normally degraded by mTORC1/S6K pathway), which suppresses eIF4A and sensitizes cells to mitotic death. A non-phosphorylatable raptor mutant reactivates mTORC1, degrades PDCD4, and reduces Taxol cytotoxicity; pharmacological eIF4A inhibition restores Taxol sensitivity in resistant cells.","method":"Raptor phosphomutant expression, PDCD4 protein monitoring during mitotic arrest, pharmacological mTORC1 inhibition, eIF4A inhibitor treatment, cell viability assay","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — genetic and pharmacological epistasis with defined mechanistic pathway and functional death/survival readout","pmids":["33027666"],"is_preprint":false},{"year":2020,"finding":"PDCD4 degradation is mediated by both the ubiquitin-proteasome system and autophagy; p62/SQSTM1 associates with PDCD4 and LC3, and PDCD4 colocalizes with autophagosomes. Knockdown of p62 or ATG5 increases PDCD4 levels, and combined proteasome plus autophagy inhibition synergistically elevates PDCD4.","method":"Co-immunoprecipitation (anti-PDCD4 pulling down p62 and LC3-II), confocal colocalization, ATG5-deficient cells, pharmacological inhibitors (MG132, bafilomycin A1), RNAi","journal":"Cells","confidence":"High","confidence_rationale":"Tier 2 — Co-IP plus genetic KO of autophagy plus colocalization, orthogonal methods confirming dual degradation route","pmids":["31952347"],"is_preprint":false},{"year":2020,"finding":"RNA-binding proteins La and HuR cooperatively bind the 3'-UTR of PDCD4 mRNA and mitigate miR-21-mediated translational repression; LPS induces cytoplasmic translocation of HuR while increasing La levels, and their cooperative binding to PDCD4 mRNA reduces cell proliferation and enhances apoptosis.","method":"RNA immunoprecipitation, subcellular fractionation, reporter assay, siRNA knockdown, apoptosis/proliferation assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — direct mRNA binding demonstrated by RIP with functional consequences, multiple orthogonal methods","pmids":["33288677"],"is_preprint":false},{"year":2019,"finding":"In GBM, PDCD4 knockdown induces senescence through p53-independent upregulation of CDK inhibitor p21, inhibition of Rb phosphorylation, and downregulation of CDKs and Rb protein; p21 knockdown rescues the senescence and growth arrest caused by PDCD4 knockdown.","method":"Stable PDCD4 knockdown in multiple hepatoma cell lines, β-galactosidase staining for senescence, p21 siRNA rescue, Western blot for Rb phosphorylation and CDKs","journal":"Frontiers in oncology","confidence":"High","confidence_rationale":"Tier 2 — epistasis via p21 knockdown rescue in multiple cell lines with clear mechanistic pathway","pmids":["30687637"],"is_preprint":false},{"year":2020,"finding":"PDCD4 deficiency in mice activates FGR (a Src-family tyrosine kinase), which upregulates NOTCH1 expression via STAT3 activation, thereby promoting tubular apoptosis and inflammation in acute kidney injury models.","method":"Pdcd4 knockout mice, IRI and cisplatin AKI models, FGR overexpression, STAT3/NOTCH1 Western blot, pharmacological tyrosine kinase inhibitor (ponatinib)","journal":"Acta pharmaceutica Sinica. B","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO plus pathway epistasis in two in vivo models, single lab","pmids":["33643819"],"is_preprint":false},{"year":2020,"finding":"EIF3H interacts with PDCD4 (co-immunoprecipitation and immunofluorescent co-localization); PDCD4 overexpression reduces EIF3H mRNA and protein by suppressing c-Jun-induced EIF3H transcription. EIF3H promotes lung adenocarcinoma invasion via EMT, and PDCD4 abrogates EIF3H-driven EMT.","method":"Co-immunoprecipitation with mass spectrometry, immunofluorescent co-localization, PDCD4 overexpression, c-Jun reporter assay, invasion/migration assays, EMT marker Western blot","journal":"American journal of cancer research","confidence":"Medium","confidence_rationale":"Tier 2–3 — Co-IP with MS identification plus functional follow-up, single lab","pmids":["32064160"],"is_preprint":false},{"year":2017,"finding":"BCR-ABL1 activates STAT5 transcription factor (via its kinase activity), which drives miR-21 transcription via STAT binding sites on the miR-21 promoter; miR-21 then suppresses PDCD4 (identified by proteomics). The same phosphoSTAT5-miR-21-PDCD4 axis operates in FLT3-ITD-driven AML.","method":"miRNA microarray profiling, STAT5 binding site mutational analysis, proteomics, tyrosine kinase inhibitor treatment, Western blot","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 — promoter mutational analysis plus proteomic identification plus kinase inhibitor epistasis, single lab","pmids":["29100302"],"is_preprint":false},{"year":2021,"finding":"PDCD4 promotes microglial inflammatory activation via a positive feedback loop with MAPK (p38, ERK, JNK) and NF-κB signaling: LPS activates MAPK/NF-κB to upregulate PDCD4, and PDCD4 in turn sustains MAPK/NF-κB activation. PDCD4 shRNA knockdown also reduces BAX and Cleaved-PARP expression, indicating a pro-apoptotic role in neurons.","method":"shRNA knockdown, LPS neuroinflammation mouse model, phospho-Western blot for MAPK/NF-κB, nuclear translocation assay for p65, apoptosis protein Western blot","journal":"Inflammation","confidence":"Medium","confidence_rationale":"Tier 2 — shRNA in vitro and in vivo with pathway phospho-blots, single lab","pmids":["34613548"],"is_preprint":false},{"year":2021,"finding":"LncRNA HOTAIR binds to Lin28 (an RNA-binding protein) and PDCD4 mRNA, stabilizing PDCD4 protein; RNA pull-down and RIP assays confirmed the HOTAIR-Lin28 and Lin28-PDCD4 interactions. This HOTAIR/Lin28/PDCD4 axis promotes LPS-induced cardiomyocyte inflammation and apoptosis.","method":"RNA pull-down, RIP assay, co-transfection knockdown/overexpression, ELISA, flow cytometry apoptosis, in vivo AAV9-sh-HOTAIR mouse model","journal":"Inflammation","confidence":"Medium","confidence_rationale":"Tier 2 — direct RNA-protein interactions validated by pull-down and RIP with functional in vivo validation, single lab","pmids":["33665757"],"is_preprint":false},{"year":2016,"finding":"Pdcd4 deficiency in mice promotes enhanced self-renewal of adipose-derived stem cells (ADSCs) via AKT activation and cyclinD1 upregulation; AKT blockade reverses the proliferative phenotype. Pdcd4 deficiency also drives white-to-beige ADSC transdifferentiation associated with UCP1 upregulation and increased lactate production.","method":"Pdcd4 knockout mice, flow cytometry for stem cell markers, colony formation assay, AKT inhibitor rescue, white adipogenic differentiation assay, UCP1 Western blot, metabolic profiling","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO with AKT inhibitor epistasis and multiple cellular phenotypes, single lab","pmids":["27031966"],"is_preprint":false},{"year":2004,"finding":"Overexpression of PDCD4 in carcinoid neuroendocrine tumor cells inhibits cell proliferation, associated with downregulation of carbonic anhydrase type II.","method":"Stable PDCD4 overexpression, cell proliferation assay, carbonic anhydrase II expression analysis","journal":"Annals of the New York Academy of Sciences","confidence":"Low","confidence_rationale":"Tier 3 — single overexpression experiment with correlative downstream target, limited mechanistic follow-up","pmids":["15153438"],"is_preprint":false}],"current_model":"PDCD4 is a tumor suppressor that primarily functions as a translation inhibitor by binding eIF4A through its two MA3 domains (structurally characterized by X-ray crystallography), blocking eIF4A helicase-mediated unwinding of structured 5'-UTRs required for translation initiation of target mRNAs including p53 and Sin1; PDCD4 is regulated by multiple E3 ubiquitin ligases (β-TrCP/SCF, SKP2, DTL/CUL4, CRL3-IBTKα) that phosphorylation-dependently ubiquitinate and proteasomally degrade it downstream of Akt/p70S6K/mTORC1 signaling, as well as by autophagy via p62; in the nucleus, PDCD4 suppresses AP-1 transcription by binding c-Jun and blocking its JNK-mediated phosphorylation and p300 co-activator recruitment, and inhibits NF-κB by directly interacting with p65 to prevent its nuclear localization; it also sequesters transcription factor Twist2 in macrophages to regulate c-Maf–IL-10 production; PDCD4 expression is post-transcriptionally repressed by miR-21 (driven by NF-κB, Akt/STAT5/BCR-ABL1, and COX-2/PGE2 pathways) acting on the PDCD4 3'-UTR, a repression counteracted by RNA-binding proteins La and HuR."},"narrative":{"teleology":[{"year":1999,"claim":"Establishing PDCD4 as a tumor suppressor: antisense depletion converted transformation-resistant cells to a sensitive phenotype, and sense re-expression reversed this, demonstrating that PDCD4 directly suppresses neoplastic transformation.","evidence":"Antisense/sense stable cell lines in mouse JB6 P−/P+ cells with phenotypic reversion","pmids":["10570194"],"confidence":"High","gaps":["Molecular mechanism of transformation suppression unknown","No target pathway identified"]},{"year":2004,"claim":"Identifying the first mechanistic target: PDCD4 suppresses AP-1 transcription by binding c-Jun, blocking JNK phosphorylation and p300 co-activator recruitment, revealing a nuclear transcriptional mechanism for tumor suppression.","evidence":"Co-immunoprecipitation, in vitro kinase assays, AP-1 luciferase reporter in mammalian cells","pmids":["15334056"],"confidence":"High","gaps":["Whether the c-Jun interaction is direct or requires bridging factors","Structural basis of PDCD4–c-Jun interaction unknown"]},{"year":2005,"claim":"Revealing how growth signaling inactivates PDCD4: Akt phosphorylates PDCD4 at Ser67/Ser457, causing nuclear translocation and loss of AP-1 suppression, connecting PDCD4 to PI3K/Akt signaling.","evidence":"In vitro kinase assay with site-directed mutagenesis, subcellular fractionation, AP-1 reporter in mammalian cells","pmids":["16357133"],"confidence":"High","gaps":["Whether phosphorylation affects other PDCD4 functions beyond AP-1","Degradation consequence of phosphorylation not yet established"]},{"year":2008,"claim":"Defining the degradation pathway: phosphorylation by Akt and p70S6K enables β-TrCP E3 ligase recognition, ubiquitination, and proteasomal degradation of PDCD4; Pdcd4-heterozygous mice confirmed haploinsufficient tumor suppression in vivo.","evidence":"In vitro ubiquitination assay, pharmacological pathway inhibitors, Pdcd4-knockout/heterozygous mouse tumor model","pmids":["18296647"],"confidence":"High","gaps":["Whether other E3 ligases contribute","Tissue-specific degradation kinetics unknown"]},{"year":2008,"claim":"Linking PDCD4 to the DNA-damage response: PDCD4 knockdown increased p21 expression and reduced UV-induced apoptosis, revealing a role in connecting PDCD4 to p53-dependent gene regulation and cell survival decisions.","evidence":"Stable shRNA knockdown in HeLa cells, p53 reporter assay, UV survival assay","pmids":["18427550"],"confidence":"High","gaps":["Whether PDCD4 acts on p53 at the transcriptional or translational level","Direct versus indirect mechanism on p53 target genes unresolved"]},{"year":2009,"claim":"Structural resolution of the translation-inhibitory mechanism: the crystal structure showed one PDCD4 bridges two eIF4A molecules via its MA3 domains, locking eIF4A in an open conformation that prevents RNA binding and helicase activity.","evidence":"X-ray crystallography of human eIF4A–PDCD4 complex with biochemical and mutagenesis validation","pmids":["19204291"],"confidence":"High","gaps":["Selectivity mechanism for specific mRNA targets unknown","Whether both eIF4A molecules must be engaged for inhibition in vivo"]},{"year":2011,"claim":"Identifying specific translational targets: PDCD4 associates with p53 mRNA and suppresses its translation via the structured 5′-UTR in an eIF4A-binding-dependent manner; DNA damage reduces PDCD4 to derepress p53 translation.","evidence":"RNA immunoprecipitation, 5′-UTR reporter constructs, eIF4A-binding mutant controls","pmids":["22033922"],"confidence":"High","gaps":["Full repertoire of translationally regulated mRNAs not defined","Whether PDCD4 contacts mRNA directly or solely via eIF4A"]},{"year":2011,"claim":"Connecting PDCD4 to innate immunity: decorin signals through TLR2/4 to upregulate PDCD4 (partly by reducing miR-21), and elevated PDCD4 suppresses IL-10, establishing PDCD4 as a switch between anti- and pro-inflammatory macrophage states.","evidence":"TLR signaling assays, miR-21 quantification, IL-10 ELISA, sepsis and xenograft mouse models","pmids":["22087031"],"confidence":"High","gaps":["Mechanism by which PDCD4 suppresses IL-10 not fully resolved","Other innate immune targets of PDCD4 not characterized"]},{"year":2012,"claim":"Placing PDCD4 degradation as essential for mTORC1-driven global translation: p70S6K1 phosphorylation of PDCD4 (and eIF4B) is required for mTORC1-stimulated protein synthesis, independent of 4E-BP/eIF4E–eIF4G axis.","evidence":"4E-BP1/2 double knockout MEFs, rapamycin, polysome profiling","pmids":["23105104"],"confidence":"High","gaps":["Relative contribution of PDCD4 versus eIF4B phosphorylation to global translation not dissected"]},{"year":2014,"claim":"Expanding nuclear functions: PDCD4 directly binds NF-κB p65, inhibiting its nuclear localization and NF-κB-dependent transcription independently of IKK/IκBα, and separately sequesters Twist2 in macrophages to control c-Maf–IL-10 production upon LPS stimulation.","evidence":"Reciprocal Co-IP, confocal imaging, ChIP for Twist2 at c-Maf promoter, pathway inhibitors in glioblastoma cells and macrophages","pmids":["24413684","24982420"],"confidence":"High","gaps":["Whether p65 and Twist2 sequestration are mutually exclusive or cell-type-specific","Structural basis of PDCD4–p65 interaction unknown"]},{"year":2015,"claim":"Identifying additional E3 ligases: CRL3-IBTKα ubiquitinates PDCD4 downstream of serum stimulation, adding a β-TrCP-independent degradation route that de-represses translation of targets including Bcl-xL.","evidence":"In vitro ubiquitination assay, affinity purification, RNAi knockdown, Bcl-xL reporter assay","pmids":["25882842"],"confidence":"High","gaps":["Phosphorylation requirements for IBTKα recognition not mapped","Relative contribution of CRL3 versus β-TrCP in different tissues unknown"]},{"year":2016,"claim":"Extending PDCD4 function to stem cell biology: Pdcd4 deficiency enhances adipose-derived stem cell self-renewal via AKT activation and promotes white-to-beige transdifferentiation with increased UCP1.","evidence":"Pdcd4 knockout mice, AKT inhibitor rescue, colony formation, UCP1 and metabolic profiling","pmids":["27031966"],"confidence":"Medium","gaps":["Whether translation of specific mRNAs drives the adipocyte phenotype","Not confirmed in independent labs","Mechanism linking PDCD4 loss to AKT activation in ADSCs unclear"]},{"year":2017,"claim":"Connecting PDCD4 to mTORC2 signaling: PDCD4 suppresses Sin1 translation via the SIN1 5′-UTR in an eIF4A-dependent manner; loss of PDCD4 activates mTORC2 and promotes invasion through Snail upregulation.","evidence":"5′-UTR reporter assay, eIF4A-binding mutant (D253A/D418A), silvestrol, invasion assays, patient tissue","pmids":["28692058"],"confidence":"High","gaps":["Whether PDCD4 regulates other mTORC2 subunit mRNAs","In vivo tumor model validation of Sin1-specific axis incomplete"]},{"year":2019,"claim":"Expanding the E3 ligase repertoire further: SKP2 and DTL/CUL4 were each shown to ubiquitinate and degrade PDCD4, demonstrating convergent multi-ligase control of PDCD4 protein levels.","evidence":"Mass spectrometry, reciprocal Co-IP, in vitro ubiquitination, xenograft rescue experiments","pmids":["30760284","31409387"],"confidence":"High","gaps":["Hierarchy and redundancy among the four E3 ligases not resolved","Phosphodegron specificity for each ligase not mapped"]},{"year":2020,"claim":"Revealing a dual degradation route: p62/SQSTM1 delivers PDCD4 to autophagosomes alongside proteasomal degradation, and combined inhibition synergistically stabilizes PDCD4, establishing autophagy as a second major turnover pathway.","evidence":"Co-IP of PDCD4–p62–LC3, ATG5-deficient cells, MG132 plus bafilomycin A1 in mammalian cells","pmids":["31952347"],"confidence":"High","gaps":["Signals that partition PDCD4 between proteasomal and autophagic degradation unknown","Whether autophagy-mediated degradation is regulated by the same phosphorylation events"]},{"year":2020,"claim":"Defining post-transcriptional stabilization of PDCD4 mRNA: La and HuR cooperatively bind the PDCD4 3′-UTR and antagonize miR-21-mediated translational repression, establishing a counterbalance to oncogenic miR-21.","evidence":"RNA immunoprecipitation, subcellular fractionation, reporter assay, siRNA knockdown","pmids":["33288677"],"confidence":"High","gaps":["Precise binding sites on PDCD4 3′-UTR for La/HuR versus miR-21 not mapped at nucleotide resolution","Whether other miRNAs are also counteracted by La/HuR"]},{"year":2020,"claim":"Linking PDCD4 to mitotic drug sensitivity: during mitotic arrest, reduced mTORC1 activity allows PDCD4 accumulation, which suppresses eIF4A-dependent translation and sensitizes cells to Taxol-induced death.","evidence":"Raptor phosphomutant, PDCD4 monitoring during arrest, eIF4A inhibitor rescue of Taxol sensitivity","pmids":["33027666"],"confidence":"High","gaps":["Specific mRNAs whose suppression mediates mitotic death not identified","Clinical relevance of PDCD4 levels for Taxol response not validated in patients"]},{"year":null,"claim":"Key open questions remain: the genome-wide repertoire of PDCD4-regulated mRNAs (translatome), the structural basis for PDCD4's nuclear protein–protein interactions with c-Jun and p65, the hierarchy and tissue specificity among the four E3 ligases, and how cells partition PDCD4 between proteasomal and autophagic degradation.","evidence":"","pmids":[],"confidence":"High","gaps":["No ribosome profiling or CLIP-seq to define the full set of PDCD4-regulated mRNAs","No structural data for PDCD4–c-Jun or PDCD4–p65 complexes","Relative contribution of each E3 ligase in physiological tissues unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[4,5,7,12,18]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[1,9,10]},{"term_id":"GO:0045182","term_label":"translation regulator activity","supporting_discovery_ids":[4,5,7,12]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1,2,9]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[2,10,19]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[4,5,7,12,18]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[1,9,17]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,7,15,25]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[6,10,25]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[19]}],"complexes":[],"partners":["EIF4A1","JUN","RELA","TWIST2","BTRC","SKP2","DTL","SQSTM1"],"other_free_text":[]},"mechanistic_narrative":"PDCD4 is a tumor suppressor that restrains cell growth and transformation by inhibiting both translation initiation and transcription factor activity. It binds eIF4A through two MA3 domains, preventing eIF4A helicase domain closure and RNA unwinding, thereby selectively suppressing cap-dependent translation of mRNAs with structured 5′-UTRs including p53 and Sin1/mTORC2 [PMID:19204291, PMID:22033922, PMID:28692058]. In the nucleus, PDCD4 suppresses AP-1 transcription by binding c-Jun to block JNK-mediated phosphorylation and p300 recruitment, and inhibits NF-κB by directly sequestering p65 to prevent its nuclear translocation; it also sequesters Twist2 in macrophages to regulate IL-10 production via c-Maf [PMID:15334056, PMID:24413684, PMID:24982420]. PDCD4 protein levels are tightly controlled by phosphorylation-dependent proteasomal degradation downstream of Akt/mTORC1/S6K signaling through multiple E3 ligases (β-TrCP, SKP2, CRL3-IBTKα, CUL4-DTL), by p62-mediated autophagy, and by miR-21-directed translational repression that is counteracted by the RNA-binding proteins La and HuR [PMID:18296647, PMID:30760284, PMID:25882842, PMID:31952347, PMID:33288677]."},"prefetch_data":{"uniprot":{"accession":"Q53EL6","full_name":"Programmed cell death protein 4","aliases":["Neoplastic transformation inhibitor protein","Nuclear antigen H731-like","Protein 197/15a"],"length_aa":469,"mass_kda":51.7,"function":"Inhibits translation initiation and cap-dependent translation. May excert its function by hindering the interaction between EIF4A1 and EIF4G. Inhibits the helicase activity of EIF4A. Modulates the activation of JUN kinase. Down-regulates the expression of MAP4K1, thus inhibiting events important in driving invasion, namely, MAPK85 activation and consequent JUN-dependent transcription. May play a role in apoptosis. Tumor suppressor. Inhibits tumor promoter-induced neoplastic transformation. 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cancers.","date":"2013","source":"Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/23838800","citation_count":27,"is_preprint":false},{"pmid":"33027666","id":"PMC_33027666","title":"The mTORC1/S6K/PDCD4/eIF4A Axis Determines Outcome of Mitotic Arrest.","date":"2020","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/33027666","citation_count":26,"is_preprint":false},{"pmid":"33907874","id":"PMC_33907874","title":"Long non-coding RNA KCNQ1OT1 increases the expression of PDCD4 by targeting miR-181a-5p, contributing to cardiomyocyte apoptosis in diabetic cardiomyopathy.","date":"2021","source":"Acta diabetologica","url":"https://pubmed.ncbi.nlm.nih.gov/33907874","citation_count":26,"is_preprint":false},{"pmid":"26252635","id":"PMC_26252635","title":"IL-6 Inhibits the Targeted Modulation of PDCD4 by miR-21 in Prostate Cancer.","date":"2015","source":"PloS 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HOTAIR Promotes LPS-Induced Inflammation and Apoptosis of Cardiomyocytes via Lin28-Mediated PDCD4 Stability.","date":"2021","source":"Inflammation","url":"https://pubmed.ncbi.nlm.nih.gov/33665757","citation_count":23,"is_preprint":false},{"pmid":"29100302","id":"PMC_29100302","title":"A tyrosine kinase-STAT5-miR21-PDCD4 regulatory axis in chronic and acute myeloid leukemia cells.","date":"2017","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/29100302","citation_count":22,"is_preprint":false},{"pmid":"25882842","id":"PMC_25882842","title":"CRL3IBTK Regulates the Tumor Suppressor Pdcd4 through Ubiquitylation Coupled to Proteasomal Degradation.","date":"2015","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25882842","citation_count":22,"is_preprint":false},{"pmid":"32358022","id":"PMC_32358022","title":"MicroRNA-21/PDCD4 Proapoptotic Signaling From Circulating CD34+ Cells to Vascular Endothelial Cells: A Potential Contributor to Adverse Cardiovascular Outcomes in Patients With Critical Limb Ischemia.","date":"2020","source":"Diabetes care","url":"https://pubmed.ncbi.nlm.nih.gov/32358022","citation_count":22,"is_preprint":false},{"pmid":"27031966","id":"PMC_27031966","title":"Pdcd4 restrains the self-renewal and white-to-beige transdifferentiation of adipose-derived stem cells.","date":"2016","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/27031966","citation_count":21,"is_preprint":false},{"pmid":"34613548","id":"PMC_34613548","title":"PDCD4 Simultaneously Promotes Microglia Activation via PDCD4-MAPK-NF-κB Positive Loop and Facilitates Neuron Apoptosis During Neuroinflammation.","date":"2021","source":"Inflammation","url":"https://pubmed.ncbi.nlm.nih.gov/34613548","citation_count":20,"is_preprint":false},{"pmid":"32064160","id":"PMC_32064160","title":"EIF3H interacts with PDCD4 enhancing lung adenocarcinoma cell metastasis.","date":"2020","source":"American journal of cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/32064160","citation_count":20,"is_preprint":false},{"pmid":"31235478","id":"PMC_31235478","title":"MicroRNA (miRNA)-to-miRNA Regulation of Programmed Cell Death 4 (PDCD4).","date":"2019","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/31235478","citation_count":20,"is_preprint":false},{"pmid":"34786071","id":"PMC_34786071","title":"miR-21-5p inhibits inflammation injuries in LPS-treated H9c2 cells by regulating PDCD4.","date":"2021","source":"American journal of translational research","url":"https://pubmed.ncbi.nlm.nih.gov/34786071","citation_count":20,"is_preprint":false},{"pmid":"33643819","id":"PMC_33643819","title":"Gene deficiency or pharmacological inhibition of PDCD4-mediated FGR signaling protects against acute kidney injury.","date":"2020","source":"Acta pharmaceutica Sinica. B","url":"https://pubmed.ncbi.nlm.nih.gov/33643819","citation_count":19,"is_preprint":false},{"pmid":"34729247","id":"PMC_34729247","title":"circ-NOL10 regulated by MTDH/CASC3 inhibits breast cancer progression and metastasis via multiple miRNAs and PDCD4.","date":"2021","source":"Molecular therapy. Nucleic acids","url":"https://pubmed.ncbi.nlm.nih.gov/34729247","citation_count":19,"is_preprint":false},{"pmid":"33837492","id":"PMC_33837492","title":"Upregulation of miR-499a-5p Decreases Cerebral Ischemia/Reperfusion Injury by Targeting PDCD4.","date":"2021","source":"Cellular and molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/33837492","citation_count":19,"is_preprint":false},{"pmid":"30861181","id":"PMC_30861181","title":"Long noncoding RNA TALNEC2 regulates myocardial ischemic injury in H9c2 cells by regulating miR-21/PDCD4-medited activation of Wnt/β-catenin pathway.","date":"2019","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/30861181","citation_count":19,"is_preprint":false},{"pmid":"28901491","id":"PMC_28901491","title":"miR‑21 attenuates contrast‑induced renal cell apoptosis by targeting PDCD4.","date":"2017","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/28901491","citation_count":18,"is_preprint":false},{"pmid":"35850313","id":"PMC_35850313","title":"Optimizing component formula suppresses lung cancer by blocking DTL-mediated PDCD4 ubiquitination to regulate the MAPK/JNK pathway.","date":"2022","source":"Journal of ethnopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/35850313","citation_count":18,"is_preprint":false},{"pmid":"33288677","id":"PMC_33288677","title":"RNA-binding proteins La and HuR cooperatively modulate translation repression of PDCD4 mRNA.","date":"2020","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/33288677","citation_count":17,"is_preprint":false},{"pmid":"33744861","id":"PMC_33744861","title":"Hsa_circ_0053063 inhibits breast cancer cell proliferation via hsa_circ_0053063/hsa-miR-330-3p/PDCD4 axis.","date":"2021","source":"Aging","url":"https://pubmed.ncbi.nlm.nih.gov/33744861","citation_count":17,"is_preprint":false},{"pmid":"31952347","id":"PMC_31952347","title":"Degradation of the Tumor Suppressor PDCD4 Is Impaired by the Suppression of p62/SQSTM1 and Autophagy.","date":"2020","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/31952347","citation_count":17,"is_preprint":false},{"pmid":"33988065","id":"PMC_33988065","title":"CircMKLN1 Suppresses the Progression of Human Retinoblastoma by Modulation of miR-425-5p/PDCD4 Axis.","date":"2021","source":"Current eye research","url":"https://pubmed.ncbi.nlm.nih.gov/33988065","citation_count":16,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":50973,"output_tokens":7106,"usd":0.129754},"stage2":{"model":"claude-opus-4-6","input_tokens":10839,"output_tokens":4162,"usd":0.237368},"total_usd":0.367122,"stage1_batch_id":"msgbatch_012ZiiCUBfB62NCTQd4Bk1Jo","stage2_batch_id":"msgbatch_01Xuqq9aUHoQouS7UVGZNStZ","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1999,\n      \"finding\": \"PDCD4 protein inhibits tumor promoter-induced neoplastic transformation; antisense-mediated reduction of PDCD4 in promotion-resistant (P-) mouse JB6 cells converts them to a transformation-sensitive (P+) phenotype, and re-expression of PDCD4 sense fragment restores the P- phenotype, establishing PDCD4 as a direct suppressor of neoplastic transformation.\",\n      \"method\": \"Antisense stable cell lines, phenotypic reversion by sense re-expression, mRNA differential display\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean loss-of-function with defined phenotypic readout plus gain-of-function rescue, replicated in multiple cell lines\",\n      \"pmids\": [\"10570194\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PDCD4 suppresses AP-1-driven transcription by interacting directly with c-Jun, blocking JNK-mediated phosphorylation of c-Jun and preventing recruitment of the co-activator p300 to c-Jun.\",\n      \"method\": \"Luciferase reporter assays, co-immunoprecipitation, in vitro kinase assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal protein interaction with functional reporter assay and mechanistic epistasis, multiple orthogonal methods in single paper\",\n      \"pmids\": [\"15334056\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Akt phosphorylates PDCD4 at Ser67 and Ser457 in vitro and in vivo, and this phosphorylation causes nuclear translocation of PDCD4 and significantly reduces its ability to suppress AP-1-dependent transcription driven by c-Jun.\",\n      \"method\": \"In vitro kinase assay, site-directed mutagenesis, luciferase reporter assay, subcellular fractionation/imaging\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinase assay with mutagenesis plus in vivo validation and functional reporter readout\",\n      \"pmids\": [\"16357133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Tumor promoter TPA triggers proteasomal degradation of PDCD4 via a PKC-PI3K-Akt-mTOR-p70S6K and MEK-ERK signaling cascade; Akt and p70S6K phosphorylate PDCD4, enabling binding of the E3-ubiquitin ligase β-TrCP and subsequent ubiquitylation and proteasomal degradation. Pdcd4-heterozygous mice show increased tumor formation, establishing PDCD4 as a haploinsufficient tumor suppressor.\",\n      \"method\": \"In vitro ubiquitination assay, pharmacological inhibitors, Pdcd4-knockout/heterozygous mouse tumor model, Western blot\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — biochemical reconstitution of ubiquitination pathway plus in vivo genetic evidence, multiple methods\",\n      \"pmids\": [\"18296647\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Crystal structure of human eIF4A–PDCD4 complex reveals that one PDCD4 molecule binds two eIF4A molecules through two distinct modes: both MA3 domains of PDCD4 bind one eIF4A, while the C-terminal MA3 domain alone contacts a second eIF4A. PDCD4 MA3 domains bind perpendicular to the eIF4A interdomain interface, preventing domain closure of eIF4A and blocking RNA binding, thereby inhibiting eIF4A helicase activity.\",\n      \"method\": \"X-ray crystallography, biochemical binding assays, mutagenesis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure with biochemical validation and mutagenesis in single study\",\n      \"pmids\": [\"19204291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PDCD4 is associated with p53 mRNA and suppresses its translation via the structured 5'-UTR of p53 mRNA in an eIF4A-interaction-dependent manner. DNA-damaging agents decrease PDCD4 levels, thereby releasing translational suppression of p53.\",\n      \"method\": \"RNA immunoprecipitation, reporter assay with 5'-UTR constructs, eIF4A-binding mutants, Western blot\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct RNA association demonstrated with eIF4A-binding mutant controls and 5'-UTR reporter dissection\",\n      \"pmids\": [\"22033922\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Decorin acts as an endogenous ligand of TLR2 and TLR4 and stimulates PDCD4 production in macrophages; decorin also reduces miR-21 abundance (which normally suppresses PDCD4 translation), thereby increasing PDCD4 levels. Elevated PDCD4 in turn decreases IL-10 release, shifting the cytokine profile toward a proinflammatory state.\",\n      \"method\": \"TLR2/4 signaling assays, miR-21 quantification, PDCD4 protein measurement, IL-10 ELISA, sepsis and xenograft mouse models\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — two independent mechanisms demonstrated with in vivo validation in multiple models\",\n      \"pmids\": [\"22087031\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"p70S6K1 phosphorylates PDCD4, and this phosphorylation (along with eIF4B phosphorylation) is required for mTORC1-mediated promotion of global protein synthesis; maintenance of eIF4E–eIF4G interaction alone is insufficient without p70S6K1 signaling to PDCD4.\",\n      \"method\": \"Genetic knockout of 4E-BP1/2, rapamycin treatment, polysome profiling, Western blot in MEFs and rat liver\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — epistasis in multiple genetic backgrounds with functional translation readout\",\n      \"pmids\": [\"23105104\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PDCD4 knockdown in HeLa cells increases expression of p21(Waf1/Cip1) and other p53-regulated genes, and PDCD4 interferes with p53-responsive promoter activation by p53. Pdcd4 knockdown cells show decreased apoptosis and increased survival after UV irradiation, implicating PDCD4 in the DNA-damage response.\",\n      \"method\": \"Stable shRNA knockdown, reporter gene assay, UV survival assay, Western blot\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean stable KD with defined transcriptional and apoptotic phenotypes plus reporter mechanistic follow-up\",\n      \"pmids\": [\"18427550\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PDCD4 directly interacts with NF-κB p65 protein (co-immunoprecipitation and confocal co-localization) in glioblastoma cells, inhibiting nuclear localization of p65 (but not p50) and suppressing NF-κB-dependent transcription independently of upstream IKK or IκBα degradation.\",\n      \"method\": \"Co-immunoprecipitation, confocal imaging, luciferase reporter assay, stable PDCD4 overexpression, qPCR of NF-κB target genes\",\n      \"journal\": \"Carcinogenesis\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP with functional reporter and subcellular localization data, orthogonal methods\",\n      \"pmids\": [\"24413684\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In macrophages, PDCD4 and transcription factor Twist2 form a complex in unstimulated cells. LPS induces PI3K/mTOR-dependent degradation of PDCD4, releasing Twist2, which then binds the c-Maf promoter to drive IL-10 production.\",\n      \"method\": \"Co-immunoprecipitation, ChIP (Twist2 at c-Maf promoter), PI3K/mTOR pharmacological inhibitors, PDCD4 knockdown, ELISA for IL-10\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — protein complex identified by Co-IP, ChIP validates downstream transcription, inhibitors confirm pathway order\",\n      \"pmids\": [\"24982420\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"IBtkα forms a CRL3(IBTK) ubiquitin ligase complex and promotes ubiquitylation and proteasomal degradation of PDCD4; serum-induced degradation of PDCD4 requires both IBtkα and Cul3. IBtkα-mediated PDCD4 degradation counteracts PDCD4-dependent translational repression, including of Bcl-xL mRNA.\",\n      \"method\": \"Affinity purification, co-immunoprecipitation, in vitro ubiquitination assay, RNAi knockdown, luciferase reporter assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro ubiquitination assay with multiple orthogonal methods and functional translation readout\",\n      \"pmids\": [\"25882842\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PDCD4 inhibits Sin1 (mTORC2 component) translation via suppression of eIF4A, using the SIN1 5'-UTR as the regulatory element. PDCD4 mutants that cannot bind eIF4A fail to repress Sin1 translation, and loss of Pdcd4 increases mTORC2 kinase activity and Snail expression, promoting colon tumor cell invasion.\",\n      \"method\": \"5'-UTR luciferase reporter assay, PDCD4 deletion/point mutants (D253A/D418A eIF4A-binding mutant), siRNA knockdown, eIF4A inhibitor silvestrol, invasion assays, patient tissue analysis\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mechanistic dissection with eIF4A-binding mutants, reporter assay, pharmacological inhibition, and in vivo correlate\",\n      \"pmids\": [\"28692058\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"DTL (a CUL4-DDB1 E3 ligase adaptor) interacts with PDCD4, promotes its ubiquitination, and accelerates its proteasomal degradation, thereby enhancing cancer cell proliferation and migration that are rescued by PDCD4 re-expression.\",\n      \"method\": \"Affinity-purification mass spectrometry, co-immunoprecipitation, in vitro ubiquitination assay, immunofluorescence, stable overexpression/knockdown lines, rescue experiment\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro ubiquitination assay with Co-IP and functional rescue experiment\",\n      \"pmids\": [\"31409387\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"SKP2 (SCF E3 ligase) promotes PDCD4 phosphorylation, ubiquitination, and proteasomal degradation. SKP2 knockdown increases PDCD4, reduces proliferation, and enhances apoptosis; these effects are reversed by simultaneous PDCD4 knockdown, placing SKP2-mediated PDCD4 degradation upstream of its tumor-suppressive function in breast cancer.\",\n      \"method\": \"Mass spectrometry, reciprocal Co-IP, in vitro ubiquitination, stable overexpression/knockdown, xenograft model\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro ubiquitination with reciprocal Co-IP and in vivo rescue\",\n      \"pmids\": [\"30760284\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PDCD4 knockdown in Pdcd4-deficient mice promotes colitis-associated colorectal cancer by upregulating IL-6 expression and enhancing IL-6/STAT3 pathway activation; blockade of IL-6/STAT3 with sgp130Fc reverses the pro-proliferative effect of PDCD4 deficiency in vivo.\",\n      \"method\": \"Pdcd4 knockout mice, DSS/AOM colitis-cancer model, cytokine ELISA, Western blot for STAT3 signaling, BrdU incorporation, sgp130Fc rescue\",\n      \"journal\": \"Inflammatory bowel diseases\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with defined in vivo pathway rescue, multiple phenotypic readouts\",\n      \"pmids\": [\"26891257\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The chicken Pdcd4 gene is a direct transcriptional target of the retroviral oncogene v-Myb; v-Myb regulates Pdcd4 expression in myelomonocytic cells, providing the first evidence that a myb transcription factor directly controls Pdcd4 expression.\",\n      \"method\": \"Differential display, inducible v-Myb expression system, promoter analysis\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct regulatory relationship shown in avian ortholog with inducible expression system, single lab\",\n      \"pmids\": [\"11313950\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PDCD4 knockdown increases MAP4K1 expression through upregulation of c-Myc, which directly binds the MAP4K1 promoter (demonstrated by ChIP), leading to enhanced JNK phosphorylation of c-Jun and AP-1-dependent transcription; dominant-negative Tcf4 reduces c-Myc and MAP4K1, connecting β-catenin/Tcf signaling to this pathway.\",\n      \"method\": \"ChIP, promoter-luciferase reporter with mutational analysis, siRNA, dominant-negative Tcf4, Western blot\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — ChIP validates direct binding, multiple orthogonal approaches in single study\",\n      \"pmids\": [\"22801218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"During mitotic arrest, mTORC1 activity is reduced due to raptor phosphorylation; this allows PDCD4 accumulation (normally degraded by mTORC1/S6K pathway), which suppresses eIF4A and sensitizes cells to mitotic death. A non-phosphorylatable raptor mutant reactivates mTORC1, degrades PDCD4, and reduces Taxol cytotoxicity; pharmacological eIF4A inhibition restores Taxol sensitivity in resistant cells.\",\n      \"method\": \"Raptor phosphomutant expression, PDCD4 protein monitoring during mitotic arrest, pharmacological mTORC1 inhibition, eIF4A inhibitor treatment, cell viability assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic and pharmacological epistasis with defined mechanistic pathway and functional death/survival readout\",\n      \"pmids\": [\"33027666\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PDCD4 degradation is mediated by both the ubiquitin-proteasome system and autophagy; p62/SQSTM1 associates with PDCD4 and LC3, and PDCD4 colocalizes with autophagosomes. Knockdown of p62 or ATG5 increases PDCD4 levels, and combined proteasome plus autophagy inhibition synergistically elevates PDCD4.\",\n      \"method\": \"Co-immunoprecipitation (anti-PDCD4 pulling down p62 and LC3-II), confocal colocalization, ATG5-deficient cells, pharmacological inhibitors (MG132, bafilomycin A1), RNAi\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus genetic KO of autophagy plus colocalization, orthogonal methods confirming dual degradation route\",\n      \"pmids\": [\"31952347\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RNA-binding proteins La and HuR cooperatively bind the 3'-UTR of PDCD4 mRNA and mitigate miR-21-mediated translational repression; LPS induces cytoplasmic translocation of HuR while increasing La levels, and their cooperative binding to PDCD4 mRNA reduces cell proliferation and enhances apoptosis.\",\n      \"method\": \"RNA immunoprecipitation, subcellular fractionation, reporter assay, siRNA knockdown, apoptosis/proliferation assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct mRNA binding demonstrated by RIP with functional consequences, multiple orthogonal methods\",\n      \"pmids\": [\"33288677\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In GBM, PDCD4 knockdown induces senescence through p53-independent upregulation of CDK inhibitor p21, inhibition of Rb phosphorylation, and downregulation of CDKs and Rb protein; p21 knockdown rescues the senescence and growth arrest caused by PDCD4 knockdown.\",\n      \"method\": \"Stable PDCD4 knockdown in multiple hepatoma cell lines, β-galactosidase staining for senescence, p21 siRNA rescue, Western blot for Rb phosphorylation and CDKs\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — epistasis via p21 knockdown rescue in multiple cell lines with clear mechanistic pathway\",\n      \"pmids\": [\"30687637\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PDCD4 deficiency in mice activates FGR (a Src-family tyrosine kinase), which upregulates NOTCH1 expression via STAT3 activation, thereby promoting tubular apoptosis and inflammation in acute kidney injury models.\",\n      \"method\": \"Pdcd4 knockout mice, IRI and cisplatin AKI models, FGR overexpression, STAT3/NOTCH1 Western blot, pharmacological tyrosine kinase inhibitor (ponatinib)\",\n      \"journal\": \"Acta pharmaceutica Sinica. B\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO plus pathway epistasis in two in vivo models, single lab\",\n      \"pmids\": [\"33643819\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"EIF3H interacts with PDCD4 (co-immunoprecipitation and immunofluorescent co-localization); PDCD4 overexpression reduces EIF3H mRNA and protein by suppressing c-Jun-induced EIF3H transcription. EIF3H promotes lung adenocarcinoma invasion via EMT, and PDCD4 abrogates EIF3H-driven EMT.\",\n      \"method\": \"Co-immunoprecipitation with mass spectrometry, immunofluorescent co-localization, PDCD4 overexpression, c-Jun reporter assay, invasion/migration assays, EMT marker Western blot\",\n      \"journal\": \"American journal of cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — Co-IP with MS identification plus functional follow-up, single lab\",\n      \"pmids\": [\"32064160\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"BCR-ABL1 activates STAT5 transcription factor (via its kinase activity), which drives miR-21 transcription via STAT binding sites on the miR-21 promoter; miR-21 then suppresses PDCD4 (identified by proteomics). The same phosphoSTAT5-miR-21-PDCD4 axis operates in FLT3-ITD-driven AML.\",\n      \"method\": \"miRNA microarray profiling, STAT5 binding site mutational analysis, proteomics, tyrosine kinase inhibitor treatment, Western blot\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — promoter mutational analysis plus proteomic identification plus kinase inhibitor epistasis, single lab\",\n      \"pmids\": [\"29100302\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PDCD4 promotes microglial inflammatory activation via a positive feedback loop with MAPK (p38, ERK, JNK) and NF-κB signaling: LPS activates MAPK/NF-κB to upregulate PDCD4, and PDCD4 in turn sustains MAPK/NF-κB activation. PDCD4 shRNA knockdown also reduces BAX and Cleaved-PARP expression, indicating a pro-apoptotic role in neurons.\",\n      \"method\": \"shRNA knockdown, LPS neuroinflammation mouse model, phospho-Western blot for MAPK/NF-κB, nuclear translocation assay for p65, apoptosis protein Western blot\",\n      \"journal\": \"Inflammation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — shRNA in vitro and in vivo with pathway phospho-blots, single lab\",\n      \"pmids\": [\"34613548\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LncRNA HOTAIR binds to Lin28 (an RNA-binding protein) and PDCD4 mRNA, stabilizing PDCD4 protein; RNA pull-down and RIP assays confirmed the HOTAIR-Lin28 and Lin28-PDCD4 interactions. This HOTAIR/Lin28/PDCD4 axis promotes LPS-induced cardiomyocyte inflammation and apoptosis.\",\n      \"method\": \"RNA pull-down, RIP assay, co-transfection knockdown/overexpression, ELISA, flow cytometry apoptosis, in vivo AAV9-sh-HOTAIR mouse model\",\n      \"journal\": \"Inflammation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct RNA-protein interactions validated by pull-down and RIP with functional in vivo validation, single lab\",\n      \"pmids\": [\"33665757\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Pdcd4 deficiency in mice promotes enhanced self-renewal of adipose-derived stem cells (ADSCs) via AKT activation and cyclinD1 upregulation; AKT blockade reverses the proliferative phenotype. Pdcd4 deficiency also drives white-to-beige ADSC transdifferentiation associated with UCP1 upregulation and increased lactate production.\",\n      \"method\": \"Pdcd4 knockout mice, flow cytometry for stem cell markers, colony formation assay, AKT inhibitor rescue, white adipogenic differentiation assay, UCP1 Western blot, metabolic profiling\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with AKT inhibitor epistasis and multiple cellular phenotypes, single lab\",\n      \"pmids\": [\"27031966\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Overexpression of PDCD4 in carcinoid neuroendocrine tumor cells inhibits cell proliferation, associated with downregulation of carbonic anhydrase type II.\",\n      \"method\": \"Stable PDCD4 overexpression, cell proliferation assay, carbonic anhydrase II expression analysis\",\n      \"journal\": \"Annals of the New York Academy of Sciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single overexpression experiment with correlative downstream target, limited mechanistic follow-up\",\n      \"pmids\": [\"15153438\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PDCD4 is a tumor suppressor that primarily functions as a translation inhibitor by binding eIF4A through its two MA3 domains (structurally characterized by X-ray crystallography), blocking eIF4A helicase-mediated unwinding of structured 5'-UTRs required for translation initiation of target mRNAs including p53 and Sin1; PDCD4 is regulated by multiple E3 ubiquitin ligases (β-TrCP/SCF, SKP2, DTL/CUL4, CRL3-IBTKα) that phosphorylation-dependently ubiquitinate and proteasomally degrade it downstream of Akt/p70S6K/mTORC1 signaling, as well as by autophagy via p62; in the nucleus, PDCD4 suppresses AP-1 transcription by binding c-Jun and blocking its JNK-mediated phosphorylation and p300 co-activator recruitment, and inhibits NF-κB by directly interacting with p65 to prevent its nuclear localization; it also sequesters transcription factor Twist2 in macrophages to regulate c-Maf–IL-10 production; PDCD4 expression is post-transcriptionally repressed by miR-21 (driven by NF-κB, Akt/STAT5/BCR-ABL1, and COX-2/PGE2 pathways) acting on the PDCD4 3'-UTR, a repression counteracted by RNA-binding proteins La and HuR.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"PDCD4 is a tumor suppressor that restrains cell growth and transformation by inhibiting both translation initiation and transcription factor activity. It binds eIF4A through two MA3 domains, preventing eIF4A helicase domain closure and RNA unwinding, thereby selectively suppressing cap-dependent translation of mRNAs with structured 5′-UTRs including p53 and Sin1/mTORC2 [PMID:19204291, PMID:22033922, PMID:28692058]. In the nucleus, PDCD4 suppresses AP-1 transcription by binding c-Jun to block JNK-mediated phosphorylation and p300 recruitment, and inhibits NF-κB by directly sequestering p65 to prevent its nuclear translocation; it also sequesters Twist2 in macrophages to regulate IL-10 production via c-Maf [PMID:15334056, PMID:24413684, PMID:24982420]. PDCD4 protein levels are tightly controlled by phosphorylation-dependent proteasomal degradation downstream of Akt/mTORC1/S6K signaling through multiple E3 ligases (β-TrCP, SKP2, CRL3-IBTKα, CUL4-DTL), by p62-mediated autophagy, and by miR-21-directed translational repression that is counteracted by the RNA-binding proteins La and HuR [PMID:18296647, PMID:30760284, PMID:25882842, PMID:31952347, PMID:33288677].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Establishing PDCD4 as a tumor suppressor: antisense depletion converted transformation-resistant cells to a sensitive phenotype, and sense re-expression reversed this, demonstrating that PDCD4 directly suppresses neoplastic transformation.\",\n      \"evidence\": \"Antisense/sense stable cell lines in mouse JB6 P−/P+ cells with phenotypic reversion\",\n      \"pmids\": [\"10570194\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism of transformation suppression unknown\", \"No target pathway identified\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Identifying the first mechanistic target: PDCD4 suppresses AP-1 transcription by binding c-Jun, blocking JNK phosphorylation and p300 co-activator recruitment, revealing a nuclear transcriptional mechanism for tumor suppression.\",\n      \"evidence\": \"Co-immunoprecipitation, in vitro kinase assays, AP-1 luciferase reporter in mammalian cells\",\n      \"pmids\": [\"15334056\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the c-Jun interaction is direct or requires bridging factors\", \"Structural basis of PDCD4–c-Jun interaction unknown\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Revealing how growth signaling inactivates PDCD4: Akt phosphorylates PDCD4 at Ser67/Ser457, causing nuclear translocation and loss of AP-1 suppression, connecting PDCD4 to PI3K/Akt signaling.\",\n      \"evidence\": \"In vitro kinase assay with site-directed mutagenesis, subcellular fractionation, AP-1 reporter in mammalian cells\",\n      \"pmids\": [\"16357133\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether phosphorylation affects other PDCD4 functions beyond AP-1\", \"Degradation consequence of phosphorylation not yet established\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Defining the degradation pathway: phosphorylation by Akt and p70S6K enables β-TrCP E3 ligase recognition, ubiquitination, and proteasomal degradation of PDCD4; Pdcd4-heterozygous mice confirmed haploinsufficient tumor suppression in vivo.\",\n      \"evidence\": \"In vitro ubiquitination assay, pharmacological pathway inhibitors, Pdcd4-knockout/heterozygous mouse tumor model\",\n      \"pmids\": [\"18296647\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether other E3 ligases contribute\", \"Tissue-specific degradation kinetics unknown\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Linking PDCD4 to the DNA-damage response: PDCD4 knockdown increased p21 expression and reduced UV-induced apoptosis, revealing a role in connecting PDCD4 to p53-dependent gene regulation and cell survival decisions.\",\n      \"evidence\": \"Stable shRNA knockdown in HeLa cells, p53 reporter assay, UV survival assay\",\n      \"pmids\": [\"18427550\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PDCD4 acts on p53 at the transcriptional or translational level\", \"Direct versus indirect mechanism on p53 target genes unresolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Structural resolution of the translation-inhibitory mechanism: the crystal structure showed one PDCD4 bridges two eIF4A molecules via its MA3 domains, locking eIF4A in an open conformation that prevents RNA binding and helicase activity.\",\n      \"evidence\": \"X-ray crystallography of human eIF4A–PDCD4 complex with biochemical and mutagenesis validation\",\n      \"pmids\": [\"19204291\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Selectivity mechanism for specific mRNA targets unknown\", \"Whether both eIF4A molecules must be engaged for inhibition in vivo\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identifying specific translational targets: PDCD4 associates with p53 mRNA and suppresses its translation via the structured 5′-UTR in an eIF4A-binding-dependent manner; DNA damage reduces PDCD4 to derepress p53 translation.\",\n      \"evidence\": \"RNA immunoprecipitation, 5′-UTR reporter constructs, eIF4A-binding mutant controls\",\n      \"pmids\": [\"22033922\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full repertoire of translationally regulated mRNAs not defined\", \"Whether PDCD4 contacts mRNA directly or solely via eIF4A\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Connecting PDCD4 to innate immunity: decorin signals through TLR2/4 to upregulate PDCD4 (partly by reducing miR-21), and elevated PDCD4 suppresses IL-10, establishing PDCD4 as a switch between anti- and pro-inflammatory macrophage states.\",\n      \"evidence\": \"TLR signaling assays, miR-21 quantification, IL-10 ELISA, sepsis and xenograft mouse models\",\n      \"pmids\": [\"22087031\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which PDCD4 suppresses IL-10 not fully resolved\", \"Other innate immune targets of PDCD4 not characterized\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Placing PDCD4 degradation as essential for mTORC1-driven global translation: p70S6K1 phosphorylation of PDCD4 (and eIF4B) is required for mTORC1-stimulated protein synthesis, independent of 4E-BP/eIF4E–eIF4G axis.\",\n      \"evidence\": \"4E-BP1/2 double knockout MEFs, rapamycin, polysome profiling\",\n      \"pmids\": [\"23105104\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of PDCD4 versus eIF4B phosphorylation to global translation not dissected\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Expanding nuclear functions: PDCD4 directly binds NF-κB p65, inhibiting its nuclear localization and NF-κB-dependent transcription independently of IKK/IκBα, and separately sequesters Twist2 in macrophages to control c-Maf–IL-10 production upon LPS stimulation.\",\n      \"evidence\": \"Reciprocal Co-IP, confocal imaging, ChIP for Twist2 at c-Maf promoter, pathway inhibitors in glioblastoma cells and macrophages\",\n      \"pmids\": [\"24413684\", \"24982420\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether p65 and Twist2 sequestration are mutually exclusive or cell-type-specific\", \"Structural basis of PDCD4–p65 interaction unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identifying additional E3 ligases: CRL3-IBTKα ubiquitinates PDCD4 downstream of serum stimulation, adding a β-TrCP-independent degradation route that de-represses translation of targets including Bcl-xL.\",\n      \"evidence\": \"In vitro ubiquitination assay, affinity purification, RNAi knockdown, Bcl-xL reporter assay\",\n      \"pmids\": [\"25882842\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphorylation requirements for IBTKα recognition not mapped\", \"Relative contribution of CRL3 versus β-TrCP in different tissues unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Extending PDCD4 function to stem cell biology: Pdcd4 deficiency enhances adipose-derived stem cell self-renewal via AKT activation and promotes white-to-beige transdifferentiation with increased UCP1.\",\n      \"evidence\": \"Pdcd4 knockout mice, AKT inhibitor rescue, colony formation, UCP1 and metabolic profiling\",\n      \"pmids\": [\"27031966\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether translation of specific mRNAs drives the adipocyte phenotype\", \"Not confirmed in independent labs\", \"Mechanism linking PDCD4 loss to AKT activation in ADSCs unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Connecting PDCD4 to mTORC2 signaling: PDCD4 suppresses Sin1 translation via the SIN1 5′-UTR in an eIF4A-dependent manner; loss of PDCD4 activates mTORC2 and promotes invasion through Snail upregulation.\",\n      \"evidence\": \"5′-UTR reporter assay, eIF4A-binding mutant (D253A/D418A), silvestrol, invasion assays, patient tissue\",\n      \"pmids\": [\"28692058\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PDCD4 regulates other mTORC2 subunit mRNAs\", \"In vivo tumor model validation of Sin1-specific axis incomplete\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Expanding the E3 ligase repertoire further: SKP2 and DTL/CUL4 were each shown to ubiquitinate and degrade PDCD4, demonstrating convergent multi-ligase control of PDCD4 protein levels.\",\n      \"evidence\": \"Mass spectrometry, reciprocal Co-IP, in vitro ubiquitination, xenograft rescue experiments\",\n      \"pmids\": [\"30760284\", \"31409387\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Hierarchy and redundancy among the four E3 ligases not resolved\", \"Phosphodegron specificity for each ligase not mapped\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Revealing a dual degradation route: p62/SQSTM1 delivers PDCD4 to autophagosomes alongside proteasomal degradation, and combined inhibition synergistically stabilizes PDCD4, establishing autophagy as a second major turnover pathway.\",\n      \"evidence\": \"Co-IP of PDCD4–p62–LC3, ATG5-deficient cells, MG132 plus bafilomycin A1 in mammalian cells\",\n      \"pmids\": [\"31952347\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signals that partition PDCD4 between proteasomal and autophagic degradation unknown\", \"Whether autophagy-mediated degradation is regulated by the same phosphorylation events\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defining post-transcriptional stabilization of PDCD4 mRNA: La and HuR cooperatively bind the PDCD4 3′-UTR and antagonize miR-21-mediated translational repression, establishing a counterbalance to oncogenic miR-21.\",\n      \"evidence\": \"RNA immunoprecipitation, subcellular fractionation, reporter assay, siRNA knockdown\",\n      \"pmids\": [\"33288677\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Precise binding sites on PDCD4 3′-UTR for La/HuR versus miR-21 not mapped at nucleotide resolution\", \"Whether other miRNAs are also counteracted by La/HuR\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Linking PDCD4 to mitotic drug sensitivity: during mitotic arrest, reduced mTORC1 activity allows PDCD4 accumulation, which suppresses eIF4A-dependent translation and sensitizes cells to Taxol-induced death.\",\n      \"evidence\": \"Raptor phosphomutant, PDCD4 monitoring during arrest, eIF4A inhibitor rescue of Taxol sensitivity\",\n      \"pmids\": [\"33027666\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific mRNAs whose suppression mediates mitotic death not identified\", \"Clinical relevance of PDCD4 levels for Taxol response not validated in patients\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key open questions remain: the genome-wide repertoire of PDCD4-regulated mRNAs (translatome), the structural basis for PDCD4's nuclear protein–protein interactions with c-Jun and p65, the hierarchy and tissue specificity among the four E3 ligases, and how cells partition PDCD4 between proteasomal and autophagic degradation.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No ribosome profiling or CLIP-seq to define the full set of PDCD4-regulated mRNAs\", \"No structural data for PDCD4–c-Jun or PDCD4–p65 complexes\", \"Relative contribution of each E3 ligase in physiological tissues unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [4, 5, 7, 12, 18]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [1, 9, 10]},\n      {\"term_id\": \"GO:0045182\", \"supporting_discovery_ids\": [4, 5, 7, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1, 2, 9]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [2, 10, 19]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [4, 5, 7, 12, 18]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [1, 9, 17]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 7, 15, 25]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [6, 10, 25]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [19]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"EIF4A1\",\n      \"JUN\",\n      \"RELA\",\n      \"TWIST2\",\n      \"BTRC\",\n      \"SKP2\",\n      \"DTL\",\n      \"SQSTM1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}