{"gene":"PFN2","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":2020,"finding":"PFN2 is a stable interaction partner of the actin N-terminal acetyltransferase NAA80. PFN2 binding to NAA80 via NAA80's proline-rich loop specifically increases NAA80's intrinsic catalytic activity. NAA80, actin, and PFN2 form a ternary complex (shown by SAXS), and PFN2 binding promotes interaction between the globular domains of actin and NAA80, facilitating actin N-terminal acetylation. The majority of cellular NAA80 is stably bound to PFN2 rather than actin, suggesting the PFN2-NAA80 complex acetylates G-actin before filament incorporation.","method":"Interaction proteomics, analytical ultracentrifugation, in vitro enzyme assays, small-angle X-ray scattering (SAXS), deletion mutagenesis of NAA80 proline-rich loop","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution in vitro with enzyme assays, structural data (SAXS), and mutagenesis in a single rigorous study","pmids":["32978259"],"is_preprint":false},{"year":2020,"finding":"PFN2 is a target of the miR-290 family of microRNAs in embryonic stem cells (ESCs). In the absence of miRNAs, PFN2 is upregulated in ESCs, causing decreased endocytosis, impaired ERK signaling, delayed cell cycle progression, and repressed differentiation. Knockout of Pfn2, reintroduction of miR-290, or disruption of the PFN2-dynamin interaction domain all reversed the endocytosis defect. Mutagenesis of the single canonical conserved 3' UTR miR-290-binding site of Pfn2 or overexpression of Pfn2 ORF alone in wild-type cells largely recapitulated these phenotypes.","method":"miRNA knockout ESCs, Pfn2 knockout, miR-290 re-introduction, Pfn2 3'UTR mutagenesis, endocytosis assays, ERK signaling assays, cell cycle analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal genetic approaches (KO, re-introduction, mutagenesis) with defined functional readouts in a single study","pmids":["32788350"],"is_preprint":false},{"year":2018,"finding":"PFN2 is ubiquitinated via differential ubiquitin-linkages (for either degradation or as a regulatory signal) by the E3 ligase cIAP1 (cellular inhibitor of apoptosis 1), targeting PFN2 for proteasomal degradation. PFN2 levels regulated by cIAP1 affect intracellular levels of reactive oxygen species.","method":"Ubiquitination assays, proteasome inhibition, E3 ligase identification, ROS measurement","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — single lab, functional E3 ligase identification with downstream ROS readout, but limited orthogonal validation in abstract","pmids":["30352681"],"is_preprint":false},{"year":2021,"finding":"In high-glucose conditions, the transcription factor ETS1 cooperates with KMT5A (which mediates H4K20 monomethylation) to regulate PFN2 promoter activity and transcription, driving endothelial-to-mesenchymal transition (EndMT) in glomerular endothelial cells. ChIP assays showed H4K20me1 and ETS1 occupy the PFN2 promoter region. Knockdown of ETS1 suppressed high glucose-induced PFN2 expression and EndMT, while ETS1 overexpression-mediated EndMT was reversed by PFN2 knockdown. KMT5A upregulation suppressed PFN2 and EndMT, while sh-KMT5A-mediated EndMT was counteracted by PFN2 knockdown.","method":"ChIP assay, dual luciferase reporter assay, siRNA knockdown, overexpression, Western blot, immunofluorescence, in vivo DN model","journal":"Molecular medicine (Cambridge, Mass.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and luciferase reporter with epistasis knockdown/overexpression experiments, single lab, multiple orthogonal methods","pmids":["34238215"],"is_preprint":false},{"year":2025,"finding":"The m6A reader hnRNPA2B1 binds to the m6A site ('AGACU') of PFN2 mRNA and enhances its stability. This hnRNPA2B1-PFN2 axis promotes ferroptosis in cardiomyocytes during myocardial ischemia-reperfusion injury, as evidenced by increased lipid ROS, MDA, and Fe2+. PFN2 knockdown attenuated ferroptosis in hnRNPA2B1-overexpressing cardiomyocytes.","method":"m6A reader interaction studies, RNA stability assay, siRNA knockdown, overexpression, ferroptosis marker measurement (lipid ROS, MDA, Fe2+, GSH, FTH1), in vitro OGD/R model and in vivo MIRI model","journal":"Free radical biology & medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — mechanistic epistasis (hnRNPA2B1→PFN2→ferroptosis) with RNA stability assays, single lab","pmids":["40010516"],"is_preprint":false},{"year":2024,"finding":"Transcription factor SIX2 directly binds to the PFN2 promoter and promotes PFN2 transcription. In turn, PFN2 promotes mRNA stability of SIX2 by recruiting RNA-binding protein YBX-1, and subsequently activates the downstream MAPK/JNK pathway, forming a SIX2/PFN2 positive feedback loop that enhances gastric cancer cell stemness.","method":"ChIP, Co-immunoprecipitation, IP-MS, RNA stability assay, RNA-sequencing, JNK pathway inhibition, gain- and loss-of-function experiments","journal":"Journal of translational medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP for direct promoter binding, CoIP for YBX-1 interaction, RNA stability assay, single lab with multiple orthogonal methods","pmids":["39256760"],"is_preprint":false},{"year":2024,"finding":"The Pfn2 3'UTR contains both a miR-290 binding site and an Iron Response Element (IRE). Deletion of the IRE leads to decreased PFN2 protein, a Wnt signaling defect, reduced nuclear beta-catenin, and a block in mesendodermal lineage differentiation. Deletion of the miR-290 site leads to increased PFN2 and reduced FGF signaling during pluripotency transition. This coordinated miRNA-IRE axis on the Pfn2 transcript controls two sequential signal transduction steps during ESC differentiation into primary germ layers.","method":"3'UTR mutagenesis (IRE deletion, miRNA site deletion), ESC differentiation assays, Wnt/FGF signaling readouts, nuclear beta-catenin measurement","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic mutagenesis of regulatory elements with defined signaling pathway readouts, single lab preprint, multiple orthogonal approaches","pmids":["bio_10.1101_2024.10.02.616359"],"is_preprint":true},{"year":2020,"finding":"PFN2 promotes proliferation, migration, invasion, and epithelial-to-mesenchymal transition (EMT) in triple-negative breast cancer (TNBC) cells. PFN2 overexpression upregulates Smad2 and Smad3, further inducing EMT. PFN2-overexpressing cells exhibit stronger tumorigenicity in vivo.","method":"CCK-8 assay, transwell migration/invasion assay, Western blot (Smad2/3, EMT markers), xenograft tumor model","journal":"Breast cancer (Tokyo, Japan)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, gain-of-function with phenotypic readout but limited mechanistic dissection of Smad pathway placement","pmids":["33047272"],"is_preprint":false},{"year":2022,"finding":"OCT1 transcription factor directly regulates PFN2 expression in AR-negative castration-resistant prostate cancer cells, as identified by ChIP-seq. PFN2 knockdown by siRNA significantly inhibited migration of AR-negative prostate cancer cells and showed a marked inhibitory effect on tumor growth in vivo.","method":"ChIP-seq, siRNA knockdown, cell migration assay, in vivo tumor growth assay, immunohistochemistry","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP-seq identifies direct OCT1 regulation of PFN2, with functional KD validation in vitro and in vivo, single lab","pmids":["35413990"],"is_preprint":false}],"current_model":"PFN2 is an actin-binding protein that functions as a stable interactor and activator of the actin N-terminal acetyltransferase NAA80 (forming a ternary complex with G-actin to promote actin acetylation), is regulated post-translationally by cIAP1-mediated ubiquitin-proteasome degradation, is post-transcriptionally suppressed by the miR-290 family to control endocytosis and ERK/FGF signaling in embryonic stem cells (with its mRNA also regulated via an Iron Response Element that controls Wnt/beta-catenin signaling during germ layer formation), and at the transcriptional level is regulated by ETS1/KMT5A-mediated epigenetic control and by OCT1, with downstream roles in EMT (via TGF-β/Smad signaling), ferroptosis (via hnRNPA2B1-mediated m6A stabilization of PFN2 mRNA), and cancer cell stemness (via a SIX2/YBX-1/JNK feedback loop)."},"narrative":{"mechanistic_narrative":"PFN2 is an actin-binding protein that couples actin homeostasis to cytoskeletal remodeling and intracellular signaling [PMID:32978259, PMID:32788350]. Biochemically, it serves as a stable activating cofactor of the actin N-terminal acetyltransferase NAA80: PFN2 binds NAA80's proline-rich loop, forms a ternary complex with G-actin, and stimulates NAA80 catalytic activity, positioning the PFN2–NAA80 complex to acetylate G-actin before its incorporation into filaments [PMID:32978259]. Through an actin/dynamin-dependent role in endocytosis, PFN2 modulates ERK and FGF signaling, cell cycle progression, and differentiation in embryonic stem cells; its level is tightly controlled by the miR-290 microRNA family acting on a conserved 3'UTR site [PMID:32788350, PMID:bio_10.1101_2024.10.02.616359]. PFN2 abundance is further set post-transcriptionally by an Iron Response Element in its 3'UTR that gates Wnt/β-catenin signaling during germ-layer specification [PMID:bio_10.1101_2024.10.02.616359], by hnRNPA2B1-mediated m6A stabilization of its mRNA [PMID:40010516], and post-translationally by cIAP1-directed ubiquitin-proteasome degradation, which in turn influences reactive oxygen species [PMID:30352681]. Transcriptionally, PFN2 is driven by ETS1 together with KMT5A-deposited H4K20me1, by OCT1, and by SIX2, and these inputs feed into context-dependent disease programs including endothelial- and epithelial-to-mesenchymal transition via TGF-β/Smad signaling, ferroptosis, and cancer cell stemness through a SIX2/YBX-1/JNK feedback loop [PMID:34238215, PMID:40010516, PMID:39256760, PMID:35413990].","teleology":[{"year":2018,"claim":"Established that PFN2 abundance is set post-translationally by targeted degradation, linking it to redox state.","evidence":"Ubiquitination assays, proteasome inhibition, and E3 ligase identification with ROS measurement","pmids":["30352681"],"confidence":"Medium","gaps":["Ubiquitin linkage specificity (degradative vs regulatory) not fully resolved","Mechanistic connection between PFN2 level and ROS not defined","Limited orthogonal validation"]},{"year":2020,"claim":"Defined PFN2's direct biochemical activity: it is a stable activator of the actin N-terminal acetyltransferase NAA80, resolving how a profilin family member contributes to actin acetylation.","evidence":"Interaction proteomics, in vitro enzyme assays, SAXS, analytical ultracentrifugation, and NAA80 proline-rich loop mutagenesis","pmids":["32978259"],"confidence":"High","gaps":["High-resolution structure of the ternary complex not determined","Cellular consequences of PFN2-dependent actin acetylation not directly tested","Whether PFN2 has NAA80-independent actin roles unresolved"]},{"year":2020,"claim":"Showed PFN2 is a functional miR-290 target whose overexpression suppresses endocytosis and ERK signaling, placing it in a microRNA circuit controlling stem cell differentiation.","evidence":"miRNA-KO and Pfn2-KO ESCs, miR-290 re-introduction, 3'UTR mutagenesis, endocytosis/ERK/cell-cycle readouts","pmids":["32788350"],"confidence":"High","gaps":["Molecular basis of PFN2–dynamin interaction in endocytosis not structurally defined","How endocytic defect connects to ERK signaling not fully mapped"]},{"year":2020,"claim":"Linked PFN2 to pro-tumorigenic EMT via TGF-β/Smad signaling in triple-negative breast cancer.","evidence":"Gain-of-function with proliferation/migration/invasion assays, Smad2/3 and EMT marker Western blots, and xenografts","pmids":["33047272"],"confidence":"Low","gaps":["Single lab gain-of-function without mechanistic placement of PFN2 in the Smad cascade","Direct interaction with Smad machinery not shown","Not independently confirmed"]},{"year":2021,"claim":"Identified transcriptional and epigenetic control of PFN2 (ETS1 + KMT5A/H4K20me1) driving endothelial-to-mesenchymal transition under high glucose.","evidence":"ChIP, dual-luciferase reporter, epistasis knockdown/overexpression, and in vivo diabetic nephropathy model","pmids":["34238215"],"confidence":"Medium","gaps":["Mechanism by which KMT5A represses while ETS1 activates the same promoter not reconciled","Downstream effectors of PFN2 in EndMT not defined"]},{"year":2022,"claim":"Established OCT1 as a direct transcriptional driver of PFN2 supporting migration and tumor growth in AR-negative castration-resistant prostate cancer.","evidence":"ChIP-seq, siRNA knockdown, migration assays, and in vivo tumor growth","pmids":["35413990"],"confidence":"Medium","gaps":["Downstream PFN2 effectors in prostate cancer migration not identified","Single-lab study"]},{"year":2024,"claim":"Revealed a SIX2/PFN2/YBX-1/JNK positive feedback loop sustaining gastric cancer stemness, showing PFN2 acts reciprocally on its own transcriptional activator.","evidence":"ChIP, Co-IP, IP-MS, RNA stability assay, RNA-seq, and JNK inhibition with gain/loss-of-function","pmids":["39256760"],"confidence":"Medium","gaps":["How PFN2 recruits YBX-1 to stabilize SIX2 mRNA mechanistically unclear","Link between PFN2 and JNK activation not biochemically defined"]},{"year":2024,"claim":"Demonstrated that a dual miR-290/IRE 3'UTR module on the Pfn2 transcript coordinates two sequential signaling steps (FGF then Wnt/β-catenin) during germ-layer formation.","evidence":"3'UTR element deletions (IRE, miRNA site), ESC differentiation, Wnt/FGF readouts, nuclear β-catenin (preprint)","pmids":["bio_10.1101_2024.10.02.616359"],"confidence":"Medium","gaps":["Iron-dependent regulation via the IRE not biochemically confirmed","Preprint, not peer-reviewed","How PFN2 level changes translate to Wnt/FGF output not mechanistically resolved"]},{"year":2025,"claim":"Connected m6A regulation to PFN2 function, showing hnRNPA2B1-mediated mRNA stabilization promotes cardiomyocyte ferroptosis in ischemia-reperfusion injury.","evidence":"m6A reader interaction, RNA stability assays, ferroptosis marker quantification, OGD/R and in vivo MIRI models","pmids":["40010516"],"confidence":"Medium","gaps":["How PFN2 protein mechanistically drives lipid ROS/ferroptosis not defined","Single-lab study"]},{"year":null,"claim":"How PFN2's core actin-acetylation cofactor activity mechanistically connects to its diverse signaling and disease roles (endocytosis, EMT, ferroptosis, stemness) remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No study links PFN2-dependent actin acetylation to its cancer or ferroptosis phenotypes","Structural basis of the ternary actin–NAA80–PFN2 complex unresolved","Whether disease functions are actin-dependent or independent is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,1]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0]}],"localization":[],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[1]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,6,5]}],"complexes":["actin–NAA80–PFN2 ternary complex"],"partners":["NAA80","ACTB","YBX1","HNRNPA2B1","CIAP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P35080","full_name":"Profilin-2","aliases":["Profilin II"],"length_aa":140,"mass_kda":15.0,"function":"Binds to actin and affects the structure of the cytoskeleton. At high concentrations, profilin prevents the polymerization of actin, whereas it enhances it at low concentrations. By binding to PIP2, it inhibits the formation of IP3 and DG","subcellular_location":"Cytoplasm, cytoskeleton","url":"https://www.uniprot.org/uniprotkb/P35080/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PFN2","classification":"Not Classified","n_dependent_lines":7,"n_total_lines":1208,"dependency_fraction":0.005794701986754967},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"ACTG1","stoichiometry":10.0},{"gene":"ACTB","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PFN2","total_profiled":1310},"omim":[{"mim_id":"276902","title":"USHER SYNDROME, TYPE IIIA; USH3A","url":"https://www.omim.org/entry/276902"},{"mim_id":"176590","title":"PROFILIN 2; PFN2","url":"https://www.omim.org/entry/176590"},{"mim_id":"159559","title":"AFADIN; AFDN","url":"https://www.omim.org/entry/159559"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"brain","ntpm":341.8}],"url":"https://www.proteinatlas.org/search/PFN2"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"P35080","domains":[{"cath_id":"3.30.450.30","chopping":"3-137","consensus_level":"high","plddt":96.1314,"start":3,"end":137}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P35080","model_url":"https://alphafold.ebi.ac.uk/files/AF-P35080-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P35080-F1-predicted_aligned_error_v6.png","plddt_mean":95.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PFN2","jax_strain_url":"https://www.jax.org/strain/search?query=PFN2"},"sequence":{"accession":"P35080","fasta_url":"https://rest.uniprot.org/uniprotkb/P35080.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P35080/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P35080"}},"corpus_meta":[{"pmid":"32522014","id":"PMC_32522014","title":"Circle RNA circABCB10 Modulates PFN2 to Promote Breast Cancer Progression, as Well as Aggravate Radioresistance Through Facilitating Glycolytic Metabolism Via miR-223-3p.","date":"2020","source":"Cancer biotherapy & radiopharmaceuticals","url":"https://pubmed.ncbi.nlm.nih.gov/32522014","citation_count":38,"is_preprint":false},{"pmid":"30628646","id":"PMC_30628646","title":"Long non‑coding RNA FOXD2‑AS1/miR‑150‑5p/PFN2 axis regulates breast cancer malignancy and tumorigenesis.","date":"2019","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/30628646","citation_count":30,"is_preprint":false},{"pmid":"34238215","id":"PMC_34238215","title":"ets1 associates with KMT5A to participate in high glucose-mediated EndMT via upregulation of PFN2 expression in diabetic nephropathy.","date":"2021","source":"Molecular medicine (Cambridge, Mass.)","url":"https://pubmed.ncbi.nlm.nih.gov/34238215","citation_count":29,"is_preprint":false},{"pmid":"32978259","id":"PMC_32978259","title":"PFN2 and NAA80 cooperate to efficiently acetylate the N-terminus of actin.","date":"2020","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/32978259","citation_count":26,"is_preprint":false},{"pmid":"33047272","id":"PMC_33047272","title":"Profilin 2 (PFN2) promotes the proliferation, migration, invasion and epithelial-to-mesenchymal transition of triple negative breast cancer cells.","date":"2020","source":"Breast cancer (Tokyo, Japan)","url":"https://pubmed.ncbi.nlm.nih.gov/33047272","citation_count":20,"is_preprint":false},{"pmid":"29449460","id":"PMC_29449460","title":"PFN2 and GAMT as common molecular determinants of axonal Charcot-Marie-Tooth disease.","date":"2018","source":"Journal of neurology, neurosurgery, and psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/29449460","citation_count":16,"is_preprint":false},{"pmid":"35413990","id":"PMC_35413990","title":"OCT1-target neural gene PFN2 promotes tumor growth in androgen receptor-negative prostate cancer.","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/35413990","citation_count":14,"is_preprint":false},{"pmid":"32042914","id":"PMC_32042914","title":"Analysis of FUS, PFN2, TDP-43, and PLS3 as potential disease severity modifiers in spinal muscular atrophy.","date":"2019","source":"Neurology. Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/32042914","citation_count":14,"is_preprint":false},{"pmid":"32788350","id":"PMC_32788350","title":"MicroRNA-dependent inhibition of PFN2 orchestrates ERK activation and pluripotent state transitions by regulating endocytosis.","date":"2020","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/32788350","citation_count":13,"is_preprint":false},{"pmid":"31799645","id":"PMC_31799645","title":"Long non-coding RNA TUG1 regulates the progression and metastasis of osteosarcoma cells via miR-140-5p/PFN2 axis.","date":"2019","source":"European review for medical and pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31799645","citation_count":13,"is_preprint":false},{"pmid":"37925795","id":"PMC_37925795","title":"Hsa_circ_0020134 promotes liver metastasis of colorectal cancer through the miR-183-5p-PFN2-TGF-β/Smad axis.","date":"2023","source":"Translational oncology","url":"https://pubmed.ncbi.nlm.nih.gov/37925795","citation_count":11,"is_preprint":false},{"pmid":"35239064","id":"PMC_35239064","title":"Circ_0008500 Knockdown Improves Radiosensitivity and Inhibits Tumorigenesis in Breast Cancer Through the miR-758-3p/PFN2 Axis.","date":"2022","source":"Journal of mammary gland biology and neoplasia","url":"https://pubmed.ncbi.nlm.nih.gov/35239064","citation_count":10,"is_preprint":false},{"pmid":"35327465","id":"PMC_35327465","title":"Impact of miR-1/miR-133 Clustered miRNAs: PFN2 Facilitates Malignant Phenotypes in Head and Neck Squamous Cell Carcinoma.","date":"2022","source":"Biomedicines","url":"https://pubmed.ncbi.nlm.nih.gov/35327465","citation_count":9,"is_preprint":false},{"pmid":"30352681","id":"PMC_30352681","title":"Ubiquitin-proteasome dependent regulation of Profilin2 (Pfn2) by a cellular inhibitor of apoptotic protein 1 (cIAP1).","date":"2018","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/30352681","citation_count":6,"is_preprint":false},{"pmid":"40010516","id":"PMC_40010516","title":"HnRNPA2B1 promotes cardiac ferroptosis via m6A-dependent stabilization of PFN2 mRNA in myocardial ischemia-reperfusion injury.","date":"2025","source":"Free radical biology & medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40010516","citation_count":5,"is_preprint":false},{"pmid":"39256760","id":"PMC_39256760","title":"The SIX2/PFN2 feedback loop promotes the stemness of gastric cancer cells.","date":"2024","source":"Journal of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/39256760","citation_count":4,"is_preprint":false},{"pmid":"37953354","id":"PMC_37953354","title":"Urinary extracellular vesicles prevent di-(2-ethylhexyl) phthalate-induced hypospadias by facilitating epithelial-mesenchymal transition via PFN2 delivery.","date":"2023","source":"Cell biology and toxicology","url":"https://pubmed.ncbi.nlm.nih.gov/37953354","citation_count":4,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.10.02.616359","title":"Coordinate post-transcriptional regulation by microRNAs and RNA binding proteins is critical for early embryonic cell fate decisions","date":"2024-10-03","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.02.616359","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12603,"output_tokens":2910,"usd":0.04073,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10167,"output_tokens":3355,"usd":0.067355,"stage2_stop_reason":"end_turn"},"total_usd":0.108085,"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\": 2020,\n      \"finding\": \"PFN2 is a stable interaction partner of the actin N-terminal acetyltransferase NAA80. PFN2 binding to NAA80 via NAA80's proline-rich loop specifically increases NAA80's intrinsic catalytic activity. NAA80, actin, and PFN2 form a ternary complex (shown by SAXS), and PFN2 binding promotes interaction between the globular domains of actin and NAA80, facilitating actin N-terminal acetylation. The majority of cellular NAA80 is stably bound to PFN2 rather than actin, suggesting the PFN2-NAA80 complex acetylates G-actin before filament incorporation.\",\n      \"method\": \"Interaction proteomics, analytical ultracentrifugation, in vitro enzyme assays, small-angle X-ray scattering (SAXS), deletion mutagenesis of NAA80 proline-rich loop\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution in vitro with enzyme assays, structural data (SAXS), and mutagenesis in a single rigorous study\",\n      \"pmids\": [\"32978259\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PFN2 is a target of the miR-290 family of microRNAs in embryonic stem cells (ESCs). In the absence of miRNAs, PFN2 is upregulated in ESCs, causing decreased endocytosis, impaired ERK signaling, delayed cell cycle progression, and repressed differentiation. Knockout of Pfn2, reintroduction of miR-290, or disruption of the PFN2-dynamin interaction domain all reversed the endocytosis defect. Mutagenesis of the single canonical conserved 3' UTR miR-290-binding site of Pfn2 or overexpression of Pfn2 ORF alone in wild-type cells largely recapitulated these phenotypes.\",\n      \"method\": \"miRNA knockout ESCs, Pfn2 knockout, miR-290 re-introduction, Pfn2 3'UTR mutagenesis, endocytosis assays, ERK signaling assays, cell cycle analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal genetic approaches (KO, re-introduction, mutagenesis) with defined functional readouts in a single study\",\n      \"pmids\": [\"32788350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PFN2 is ubiquitinated via differential ubiquitin-linkages (for either degradation or as a regulatory signal) by the E3 ligase cIAP1 (cellular inhibitor of apoptosis 1), targeting PFN2 for proteasomal degradation. PFN2 levels regulated by cIAP1 affect intracellular levels of reactive oxygen species.\",\n      \"method\": \"Ubiquitination assays, proteasome inhibition, E3 ligase identification, ROS measurement\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — single lab, functional E3 ligase identification with downstream ROS readout, but limited orthogonal validation in abstract\",\n      \"pmids\": [\"30352681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In high-glucose conditions, the transcription factor ETS1 cooperates with KMT5A (which mediates H4K20 monomethylation) to regulate PFN2 promoter activity and transcription, driving endothelial-to-mesenchymal transition (EndMT) in glomerular endothelial cells. ChIP assays showed H4K20me1 and ETS1 occupy the PFN2 promoter region. Knockdown of ETS1 suppressed high glucose-induced PFN2 expression and EndMT, while ETS1 overexpression-mediated EndMT was reversed by PFN2 knockdown. KMT5A upregulation suppressed PFN2 and EndMT, while sh-KMT5A-mediated EndMT was counteracted by PFN2 knockdown.\",\n      \"method\": \"ChIP assay, dual luciferase reporter assay, siRNA knockdown, overexpression, Western blot, immunofluorescence, in vivo DN model\",\n      \"journal\": \"Molecular medicine (Cambridge, Mass.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and luciferase reporter with epistasis knockdown/overexpression experiments, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"34238215\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The m6A reader hnRNPA2B1 binds to the m6A site ('AGACU') of PFN2 mRNA and enhances its stability. This hnRNPA2B1-PFN2 axis promotes ferroptosis in cardiomyocytes during myocardial ischemia-reperfusion injury, as evidenced by increased lipid ROS, MDA, and Fe2+. PFN2 knockdown attenuated ferroptosis in hnRNPA2B1-overexpressing cardiomyocytes.\",\n      \"method\": \"m6A reader interaction studies, RNA stability assay, siRNA knockdown, overexpression, ferroptosis marker measurement (lipid ROS, MDA, Fe2+, GSH, FTH1), in vitro OGD/R model and in vivo MIRI model\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — mechanistic epistasis (hnRNPA2B1→PFN2→ferroptosis) with RNA stability assays, single lab\",\n      \"pmids\": [\"40010516\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Transcription factor SIX2 directly binds to the PFN2 promoter and promotes PFN2 transcription. In turn, PFN2 promotes mRNA stability of SIX2 by recruiting RNA-binding protein YBX-1, and subsequently activates the downstream MAPK/JNK pathway, forming a SIX2/PFN2 positive feedback loop that enhances gastric cancer cell stemness.\",\n      \"method\": \"ChIP, Co-immunoprecipitation, IP-MS, RNA stability assay, RNA-sequencing, JNK pathway inhibition, gain- and loss-of-function experiments\",\n      \"journal\": \"Journal of translational medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP for direct promoter binding, CoIP for YBX-1 interaction, RNA stability assay, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"39256760\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The Pfn2 3'UTR contains both a miR-290 binding site and an Iron Response Element (IRE). Deletion of the IRE leads to decreased PFN2 protein, a Wnt signaling defect, reduced nuclear beta-catenin, and a block in mesendodermal lineage differentiation. Deletion of the miR-290 site leads to increased PFN2 and reduced FGF signaling during pluripotency transition. This coordinated miRNA-IRE axis on the Pfn2 transcript controls two sequential signal transduction steps during ESC differentiation into primary germ layers.\",\n      \"method\": \"3'UTR mutagenesis (IRE deletion, miRNA site deletion), ESC differentiation assays, Wnt/FGF signaling readouts, nuclear beta-catenin measurement\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic mutagenesis of regulatory elements with defined signaling pathway readouts, single lab preprint, multiple orthogonal approaches\",\n      \"pmids\": [\"bio_10.1101_2024.10.02.616359\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PFN2 promotes proliferation, migration, invasion, and epithelial-to-mesenchymal transition (EMT) in triple-negative breast cancer (TNBC) cells. PFN2 overexpression upregulates Smad2 and Smad3, further inducing EMT. PFN2-overexpressing cells exhibit stronger tumorigenicity in vivo.\",\n      \"method\": \"CCK-8 assay, transwell migration/invasion assay, Western blot (Smad2/3, EMT markers), xenograft tumor model\",\n      \"journal\": \"Breast cancer (Tokyo, Japan)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, gain-of-function with phenotypic readout but limited mechanistic dissection of Smad pathway placement\",\n      \"pmids\": [\"33047272\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"OCT1 transcription factor directly regulates PFN2 expression in AR-negative castration-resistant prostate cancer cells, as identified by ChIP-seq. PFN2 knockdown by siRNA significantly inhibited migration of AR-negative prostate cancer cells and showed a marked inhibitory effect on tumor growth in vivo.\",\n      \"method\": \"ChIP-seq, siRNA knockdown, cell migration assay, in vivo tumor growth assay, immunohistochemistry\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP-seq identifies direct OCT1 regulation of PFN2, with functional KD validation in vitro and in vivo, single lab\",\n      \"pmids\": [\"35413990\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PFN2 is an actin-binding protein that functions as a stable interactor and activator of the actin N-terminal acetyltransferase NAA80 (forming a ternary complex with G-actin to promote actin acetylation), is regulated post-translationally by cIAP1-mediated ubiquitin-proteasome degradation, is post-transcriptionally suppressed by the miR-290 family to control endocytosis and ERK/FGF signaling in embryonic stem cells (with its mRNA also regulated via an Iron Response Element that controls Wnt/beta-catenin signaling during germ layer formation), and at the transcriptional level is regulated by ETS1/KMT5A-mediated epigenetic control and by OCT1, with downstream roles in EMT (via TGF-β/Smad signaling), ferroptosis (via hnRNPA2B1-mediated m6A stabilization of PFN2 mRNA), and cancer cell stemness (via a SIX2/YBX-1/JNK feedback loop).\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PFN2 is an actin-binding protein that couples actin homeostasis to cytoskeletal remodeling and intracellular signaling [#0, #1]. Biochemically, it serves as a stable activating cofactor of the actin N-terminal acetyltransferase NAA80: PFN2 binds NAA80's proline-rich loop, forms a ternary complex with G-actin, and stimulates NAA80 catalytic activity, positioning the PFN2–NAA80 complex to acetylate G-actin before its incorporation into filaments [#0]. Through an actin/dynamin-dependent role in endocytosis, PFN2 modulates ERK and FGF signaling, cell cycle progression, and differentiation in embryonic stem cells; its level is tightly controlled by the miR-290 microRNA family acting on a conserved 3'UTR site [#1, #6]. PFN2 abundance is further set post-transcriptionally by an Iron Response Element in its 3'UTR that gates Wnt/β-catenin signaling during germ-layer specification [#6], by hnRNPA2B1-mediated m6A stabilization of its mRNA [#4], and post-translationally by cIAP1-directed ubiquitin-proteasome degradation, which in turn influences reactive oxygen species [#2]. Transcriptionally, PFN2 is driven by ETS1 together with KMT5A-deposited H4K20me1, by OCT1, and by SIX2, and these inputs feed into context-dependent disease programs including endothelial- and epithelial-to-mesenchymal transition via TGF-β/Smad signaling, ferroptosis, and cancer cell stemness through a SIX2/YBX-1/JNK feedback loop [#3, #4, #5, #8].\",\n  \"teleology\": [\n    {\n      \"year\": 2018,\n      \"claim\": \"Established that PFN2 abundance is set post-translationally by targeted degradation, linking it to redox state.\",\n      \"evidence\": \"Ubiquitination assays, proteasome inhibition, and E3 ligase identification with ROS measurement\",\n      \"pmids\": [\"30352681\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Ubiquitin linkage specificity (degradative vs regulatory) not fully resolved\", \"Mechanistic connection between PFN2 level and ROS not defined\", \"Limited orthogonal validation\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined PFN2's direct biochemical activity: it is a stable activator of the actin N-terminal acetyltransferase NAA80, resolving how a profilin family member contributes to actin acetylation.\",\n      \"evidence\": \"Interaction proteomics, in vitro enzyme assays, SAXS, analytical ultracentrifugation, and NAA80 proline-rich loop mutagenesis\",\n      \"pmids\": [\"32978259\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"High-resolution structure of the ternary complex not determined\", \"Cellular consequences of PFN2-dependent actin acetylation not directly tested\", \"Whether PFN2 has NAA80-independent actin roles unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed PFN2 is a functional miR-290 target whose overexpression suppresses endocytosis and ERK signaling, placing it in a microRNA circuit controlling stem cell differentiation.\",\n      \"evidence\": \"miRNA-KO and Pfn2-KO ESCs, miR-290 re-introduction, 3'UTR mutagenesis, endocytosis/ERK/cell-cycle readouts\",\n      \"pmids\": [\"32788350\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Molecular basis of PFN2–dynamin interaction in endocytosis not structurally defined\", \"How endocytic defect connects to ERK signaling not fully mapped\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Linked PFN2 to pro-tumorigenic EMT via TGF-β/Smad signaling in triple-negative breast cancer.\",\n      \"evidence\": \"Gain-of-function with proliferation/migration/invasion assays, Smad2/3 and EMT marker Western blots, and xenografts\",\n      \"pmids\": [\"33047272\"],\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single lab gain-of-function without mechanistic placement of PFN2 in the Smad cascade\", \"Direct interaction with Smad machinery not shown\", \"Not independently confirmed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified transcriptional and epigenetic control of PFN2 (ETS1 + KMT5A/H4K20me1) driving endothelial-to-mesenchymal transition under high glucose.\",\n      \"evidence\": \"ChIP, dual-luciferase reporter, epistasis knockdown/overexpression, and in vivo diabetic nephropathy model\",\n      \"pmids\": [\"34238215\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Mechanism by which KMT5A represses while ETS1 activates the same promoter not reconciled\", \"Downstream effectors of PFN2 in EndMT not defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established OCT1 as a direct transcriptional driver of PFN2 supporting migration and tumor growth in AR-negative castration-resistant prostate cancer.\",\n      \"evidence\": \"ChIP-seq, siRNA knockdown, migration assays, and in vivo tumor growth\",\n      \"pmids\": [\"35413990\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Downstream PFN2 effectors in prostate cancer migration not identified\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Revealed a SIX2/PFN2/YBX-1/JNK positive feedback loop sustaining gastric cancer stemness, showing PFN2 acts reciprocally on its own transcriptional activator.\",\n      \"evidence\": \"ChIP, Co-IP, IP-MS, RNA stability assay, RNA-seq, and JNK inhibition with gain/loss-of-function\",\n      \"pmids\": [\"39256760\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"How PFN2 recruits YBX-1 to stabilize SIX2 mRNA mechanistically unclear\", \"Link between PFN2 and JNK activation not biochemically defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrated that a dual miR-290/IRE 3'UTR module on the Pfn2 transcript coordinates two sequential signaling steps (FGF then Wnt/β-catenin) during germ-layer formation.\",\n      \"evidence\": \"3'UTR element deletions (IRE, miRNA site), ESC differentiation, Wnt/FGF readouts, nuclear β-catenin (preprint)\",\n      \"pmids\": [\"bio_10.1101_2024.10.02.616359\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Iron-dependent regulation via the IRE not biochemically confirmed\", \"Preprint, not peer-reviewed\", \"How PFN2 level changes translate to Wnt/FGF output not mechanistically resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected m6A regulation to PFN2 function, showing hnRNPA2B1-mediated mRNA stabilization promotes cardiomyocyte ferroptosis in ischemia-reperfusion injury.\",\n      \"evidence\": \"m6A reader interaction, RNA stability assays, ferroptosis marker quantification, OGD/R and in vivo MIRI models\",\n      \"pmids\": [\"40010516\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"How PFN2 protein mechanistically drives lipid ROS/ferroptosis not defined\", \"Single-lab study\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How PFN2's core actin-acetylation cofactor activity mechanistically connects to its diverse signaling and disease roles (endocytosis, EMT, ferroptosis, stemness) remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No study links PFN2-dependent actin acetylation to its cancer or ferroptosis phenotypes\", \"Structural basis of the ternary actin–NAA80–PFN2 complex unresolved\", \"Whether disease functions are actin-dependent or independent is unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 6, 5]}\n    ],\n    \"complexes\": [\"actin–NAA80–PFN2 ternary complex\"],\n    \"partners\": [\"NAA80\", \"ACTB\", \"YBX1\", \"hnRNPA2B1\", \"cIAP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}