{"gene":"PIWIL1","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":2002,"finding":"HIWI (PIWIL1) protein is specifically expressed in germline cells of the human testis, detectable in spermatocytes and round spermatids during spermatogenesis, and its transient overexpression in the human leukemia cell line KG1 caused a dramatic reduction in cellular proliferation and induced programmed cell death (Annexin V assay), suggesting a role as a negative developmental regulator.","method":"RT-PCR, immunohistochemistry, transient transfection overexpression, Annexin V apoptosis assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single lab, multiple methods (IHC, overexpression, apoptosis assay) but no pathway-level mechanistic dissection","pmids":["12037681"],"is_preprint":false},{"year":2001,"finding":"HIWI (PIWIL1) is expressed in human CD34+ hematopoietic progenitor/stem cells but not in more differentiated cell populations; overexpression in KG1 cells reduced proliferation and induced apoptosis, implicating HIWI in stem cell self-renewal regulation.","method":"RT-PCR, 5' RACE cloning, transient transfection, cell proliferation assay, Annexin V apoptosis assay","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single lab, multiple orthogonal methods (expression, overexpression, apoptosis assay), but limited mechanistic pathway placement","pmids":["11154219"],"is_preprint":false},{"year":2010,"finding":"PIWI proteins (including PIWIL1/HIWI) contain symmetrical dimethyl arginines (sDMAs) installed by the methyltransferase PRMT5 (Dart5/Capsuleen), and this modification mediates interaction with multiple Tudor (Tud) domain family proteins through sDMA-binding Tudor domains.","method":"Biochemical analysis, methyltransferase assays, co-immunoprecipitation, review of prior experimental findings","journal":"Genes & development","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — based on synthesis of prior experimental results (reciprocal Co-IP, biochemical assays from multiple labs) described in this review","pmids":["20360382"],"is_preprint":false},{"year":2017,"finding":"The extended Tudor domain of mammalian TDRD2 preferentially recognizes an unmethylated arginine-rich sequence from PIWIL1, in contrast to most Tudor domains that bind methylated PIWI proteins. Structural studies revealed that the interface of Tudor and staphylococcal nuclease domains mediates PIWIL1 peptide recognition. Mutations disrupting the TDRD2-PIWIL1 interaction compromised piRNA maturation via 3'-end trimming in vitro.","method":"Crystal structure determination, in vitro binding assays, mutagenesis, in vitro trimming assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with mutagenesis and in vitro functional validation in a single rigorous study","pmids":["29118143"],"is_preprint":false},{"year":2022,"finding":"GTSF1 potentiates the weak intrinsic piRNA-directed RNA cleavage activity of PIWI proteins including MIWI (PIWIL1), transforming them into efficient endoribonucleases. The piRNA-guided endoribonuclease activities of MIWI (PIWIL1) and MILI are essential for the production of functional sperm.","method":"In vitro cleavage assay, biochemical reconstitution, mouse knockout phenotype","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of catalytic activity with auxiliary factor, corroborated by mouse KO fertility phenotypes","pmids":["35772669"],"is_preprint":false},{"year":2023,"finding":"Unlike AGO-clade Argonaute proteins, PIWI proteins (tested with mouse MIWI/PIWIL1 and sponge PIWI) efficiently cleave target transcripts that are only partially base-paired to their piRNA guides. PIWI slicing tolerates mismatches to any target nucleotide including those flanking the scissile phosphate, and seed pairing is dispensable for PIWI binding or cleavage, in contrast to AGO proteins.","method":"In vitro target binding and cleavage assays with recombinant mouse and sponge PIWI proteins, mutational analysis of target:piRNA pairing","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — rigorous in vitro biochemical reconstitution with multiple orthogonal experiments across two PIWI proteins","pmids":["37344600"],"is_preprint":false},{"year":2024,"finding":"Cryo-EM structural studies of mammalian MILI (PIWIL2) and human HILI piRNA-induced silencing complexes (piRISCs) revealed that they bind and cleave targets more efficiently than invertebrate counterparts, adopt a wider nucleic-acid-binding channel, and display an extended prearranged piRNA seed in the absence of target. A vertebrate-specific lysine distorts the piRNA seed, shifting the trajectory of the piRNA-target duplex, and promotes target binding and cleavage. In the presence of target, the seed gate adopts a relaxed state, enabling PIWI tolerance of seed-target mismatches.","method":"Cryo-EM structure determination, in vitro binding and cleavage assays, mutagenesis of vertebrate-specific lysine","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structures with functional mutagenesis and in vitro assays in a single rigorous study; directly characterizes human HILI (PIWIL2) and provides molecular basis applicable to mammalian PIWI clade including PIWIL1","pmids":["38658622"],"is_preprint":false},{"year":2020,"finding":"PIWIL1 is highly expressed in gastric cancer tissues and cell lines. PIWIL1 knockout drastically reduces gastric cancer cell proliferation, migration, metastasis, and tumorigenesis. Surprisingly, few bona fide piRNAs exist in gastric cancer cells, and abolishing the piRNA-binding activity of PIWIL1 does not affect its oncogenic function. PIWIL1 function in gastric cancer involves piRNA-independent interaction with the UPF1-mediated nonsense-mediated mRNA decay (NMD) mechanism.","method":"PIWIL1 knockout (PIWIL1-KO), RNA deep sequencing, piRNA-binding mutant functional rescue, co-immunoprecipitation with NMD factors","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with defined proliferative/metastatic phenotype, piRNA-binding mutant used to separate piRNA-dependent from independent functions, biochemical interaction with NMD pathway identified","pmids":["32848063"],"is_preprint":false},{"year":2015,"finding":"PIWIL1 directly binds to Stathmin1, upregulates Stathmin1 expression by inhibiting ubiquitin-mediated degradation induced by the E3 ubiquitin ligase RLIM, and reduces phosphorylation of Stathmin1 at Ser-16 by inhibiting the interaction between CaMKII and Stathmin1. Through these mechanisms PIWIL1 suppresses microtubule polymerization and promotes cell proliferation and migration.","method":"Co-immunoprecipitation (direct binding), Western blot, ubiquitination assay, phosphorylation assay, microtubule polymerization assay, cell proliferation and migration assays","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding shown by Co-IP, multiple functional readouts (ubiquitination, phosphorylation, microtubule dynamics), single lab","pmids":["26317901"],"is_preprint":false},{"year":2012,"finding":"Overexpression of HIWI (PIWIL1) in sarcoma precursors inhibits their differentiation in vitro and generates sarcomas in vivo. Transgenic mice expressing mesodermally-restricted Hiwi develop sarcomas. Inducible downregulation of Hiwi in human sarcomas inhibits growth and re-establishes differentiation. Hiwi-associated tumorigenesis is accompanied by increased global DNA methylation and silencing of cyclin-dependent kinase inhibitors (CDKIs), which is reversible with DNA methyltransferase inhibitors.","method":"In vitro differentiation assays, transgenic mouse model, inducible knockdown, DNA methylation analysis, DNMT inhibitor treatment","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal in vitro and in vivo models (cell culture, transgenic mice, inducible KD) with mechanistic link to DNA methylation and CDKI silencing","pmids":["22438986"],"is_preprint":false},{"year":2021,"finding":"Piwil1 (HIWI) is enriched in glioma stem-like cells (GSCs) and maintains self-renewal. Silencing Piwil1 in GSCs leads to global gene expression changes resulting in cell-cycle arrest, senescence, or apoptosis. Piwil1 knockdown increases expression of BTG2 and FBXW7 (leading to reduced c-Myc and loss of Olig2/Nestin), and Piwil1 regulates mRNA stability of BTG2, FBXW7, and CDKN1B. In animal models, Piwil1 knockdown suppresses tumor growth.","method":"shRNA knockdown, RNA-seq, mRNA stability assay, xenograft mouse models, Western blot","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KD with defined cellular phenotype, RNA-seq, mRNA stability assay, in vivo validation; single lab","pmids":["33406417"],"is_preprint":false},{"year":2021,"finding":"PIWIL1 in HCC increases oxygen consumption and energy production via fatty acid metabolism without altering aerobic glycolysis. PIWIL1-overexpressing HCC cells attract myeloid-derived suppressor cells (MDSCs) into the tumor microenvironment. Complement C3, whose secretion is induced by PIWIL1 in HCC cells, mediates the interaction with MDSCs by activating p38 MAPK signaling in MDSCs, which initiates immunosuppressive IL-10 expression.","method":"PIWIL1 overexpression/knockdown, metabolic flux analysis, RNA-seq, MDSC co-culture, C3 neutralization, p38 MAPK inhibition","journal":"Signal transduction and targeted therapy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal functional assays (metabolism, immune cell recruitment, signaling), single lab","pmids":["33633112"],"is_preprint":false},{"year":2019,"finding":"PIWIL1 localizes in a nuage-like perinuclear structure in colorectal cancer (COLO 205) cells. RNA immunoprecipitation revealed piRNAs loaded into PIWIL1 that form complexes also comprising target mRNAs encoding key regulatory proteins involved in colorectal carcinogenesis.","method":"Immunofluorescence localization, RNA immunoprecipitation (RIP), piRNA methylation analysis, RNA sequencing","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by immunofluorescence, RIP demonstrating PIWIL1-piRNA-mRNA complex formation; single lab","pmids":["31694219"],"is_preprint":false},{"year":2012,"finding":"RASSF1C overexpression increases PIWIL1 gene expression in non-small cell lung cancer cells, and RASSF1C silencing decreases PIWIL1 expression. Inhibition of the MEK-ERK1/2 pathway suppresses PIWIL1 expression, suggesting RASSF1C regulates PIWIL1 through activation of the MEK-ERK1/2 pathway.","method":"RASSF1C overexpression, siRNA knockdown, Affymetrix microarray, qRT-PCR, Western blot, immunostaining, MEK inhibitor treatment","journal":"BMC research notes","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, indirect pathway placement via pharmacological inhibition, no direct mechanistic link between ERK and PIWIL1 promoter","pmids":["22591718"],"is_preprint":false},{"year":2021,"finding":"PIWIL1 interacting with piR-017061 facilitates EFNA5 mRNA degradation in pancreatic cancer cells. Loss of piR-017061 results in EFNA5 accumulation, which promotes pancreatic cancer development. Direct binding between piR-017061 and EFNA5 mRNA is mediated by PIWIL1.","method":"RNA immunoprecipitation, qRT-PCR, cell proliferation assay, in vivo xenograft, mRNA stability assay","journal":"Human cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RIP demonstrating PIWIL1-piRNA-target mRNA complex, functional in vitro and in vivo validation; single lab","pmids":["33389678"],"is_preprint":false},{"year":2015,"finding":"HENMT1 and PIWIL1 are coexpressed in pachytene spermatocytes and spermatids in the human testis, and samples expressing HENMT1, PIWIL1, and PIWIL2 showed significantly lower transposon (LINE-1) expression compared to samples without expression, supporting conservation of the transposon-regulating piRNA pathway function in adult human testis.","method":"Immunolocalization, RT-PCR after laser microdissection, RT-qPCR in 222 testis biopsies, HENMT1-overexpressing cell lines","journal":"Reproduction (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct colocalization, corroborated by functional overexpression data in cell lines and correlation across large tissue sample set","pmids":["28676534"],"is_preprint":false},{"year":2023,"finding":"In golden hamsters, knockout of PIWIL1 leads to female sterility (PIWIL1 is highly expressed throughout oogenesis and early embryogenesis), and PIWIL1 can partially compensate for TE silencing in PIWIL3 knockout females. In testes, PIWIL1 is the predominant PIWI in adult hamsters, and loss of PIWIL1 causes sterility with severe spermatogenesis disorders.","method":"CRISPR/Cas9 knockout, immunofluorescence subcellular localization, RNA-seq, fertility assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with defined reproductive phenotypes in both sexes, TE silencing analysis, and expression profiling; replicated across all four PIWI family members in a single rigorous study","pmids":["37644029"],"is_preprint":false},{"year":2015,"finding":"In human testes, PIWIL1 is expressed in spermatocytes and spermatids and is associated with transposon silencing. Expression of PIWIL1 in oocytes of adult human and bovine ovaries was demonstrated, with PIWIL1 expressed in adult human and bovine oocytes (bovine oocytes exclusively expressed PIWIL1 among PIWI family members).","method":"Immunohistochemistry, Western blot, quantitative proteome analysis, small RNA sequencing","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct protein localization and expression by proteomics and IHC across multiple species, single study","pmids":["25818294"],"is_preprint":false},{"year":2015,"finding":"PIWIL1 overexpression in endometrial cancer cells maintained stem-like characteristics including enhanced migration, invasion, and sphere-forming activity, and induced an EMT-like phenotype with increased mesenchymal markers and suppression of E-cadherin, as well as upregulated CD44 and ALDH1 expression.","method":"Stable transfection/shRNA knockdown, MTT assay, colony formation, transwell invasion, xenograft, qRT-PCR, Western blot, immunofluorescence","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — multiple functional assays with gain- and loss-of-function, in vitro and in vivo, but pathway mechanism not directly elucidated; single lab","pmids":["26506848"],"is_preprint":false},{"year":2019,"finding":"Viral-mediated knockdown of Piwil1 in the dorsal hippocampus of adult mice leads to enhanced contextual fear memory without affecting generalized anxiety, implicating PIWIL1 in behavioral regulation in the adult mammalian brain through modulation of plasticity-related gene expression.","method":"Viral-mediated shRNA knockdown in vivo, contextual fear conditioning behavioral assay","journal":"Neurobiology of learning and memory","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single behavioral readout, no direct molecular mechanism identified","pmids":["30965112"],"is_preprint":false},{"year":2015,"finding":"In colorectal cancer cells, Hiwi (PIWIL1) overexpression promoted cell proliferation and increased global DNA methylation levels. Chemical inhibition of DNA methylation significantly restrained this proliferation-promoting effect, suggesting PIWIL1 promotes cancer cell proliferation via increasing global DNA methylation.","method":"Adenovirus-mediated overexpression, cell proliferation assay, global DNA methylation measurement, DNMT inhibitor treatment","journal":"Disease markers","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, indirect mechanistic link (pharmacological inhibition of downstream effector), no direct molecular mechanism identified","pmids":["26355242"],"is_preprint":false}],"current_model":"PIWIL1 (HIWI) is a PIWI-clade Argonaute protein that associates with piRNAs to form piRNA-induced silencing complexes (piRISCs) that cleave target transposon transcripts via an endonuclease activity potentiated by the accessory factor GTSF1; unlike AGO proteins, PIWIL1 tolerates extensive piRNA:target mismatches to broadly silence transposons. PIWIL1 contains symmetrical dimethyl-arginine modifications installed by PRMT5, enabling methylation-dependent Tudor domain interactions, while TDRD2 recognizes PIWIL1 via a methylation-independent mechanism that is required for piRNA 3'-end trimming. In somatic cancer contexts, PIWIL1 acts via piRNA-independent mechanisms, notably interacting with the UPF1-mediated nonsense-mediated mRNA decay pathway in gastric cancer, regulating mRNA stability of tumor suppressors in glioblastoma, binding and stabilizing Stathmin1 (suppressing its ubiquitination and phosphorylation) to destabilize microtubules and promote cell migration, and inducing global DNA hypermethylation to silence CDKI genes and drive tumorigenesis."},"narrative":{"mechanistic_narrative":"PIWIL1 (HIWI) is a PIWI-clade Argonaute that, in the germline, loads piRNAs to form piRNA-induced silencing complexes (piRISCs) that direct transposon silencing during spermatogenesis and oogenesis [PMID:28676534, PMID:37644029, PMID:25818294]. As a piRNA-guided endoribonuclease, its weak intrinsic slicing activity is potentiated into efficient target cleavage by the accessory factor GTSF1, and this catalytic activity is essential for functional sperm production [PMID:35772669]. Unlike AGO-clade Argonautes, PIWIL1 cleaves targets that are only partially base-paired to its piRNA guide, tolerating mismatches at any position and dispensing with seed pairing [PMID:37344600]; cryo-EM of mammalian PIWI piRISCs attributes this mismatch tolerance to a wider nucleic-acid channel and a vertebrate-specific lysine that distorts the piRNA seed and relaxes the seed gate upon target engagement [PMID:38658622]. PIWIL1 carries symmetrical dimethyl-arginine marks installed by PRMT5 that mediate methylation-dependent Tudor-domain interactions [PMID:20360382], whereas TDRD2 recognizes an unmethylated arginine-rich PIWIL1 sequence in a methylation-independent manner required for piRNA 3'-end trimming [PMID:29118143]. In somatic cancers PIWIL1 acts largely independently of piRNAs: in gastric cancer its oncogenic function persists when piRNA binding is abolished and operates through interaction with the UPF1-dependent nonsense-mediated mRNA decay machinery [PMID:32848063]; in glioma stem cells it sustains self-renewal by regulating the mRNA stability of tumor suppressors BTG2, FBXW7, and CDKN1B [PMID:33406417]; it binds and stabilizes Stathmin1 by blocking its RLIM-mediated ubiquitination and CaMKII-mediated phosphorylation, thereby destabilizing microtubules and promoting migration [PMID:26317901]; and it drives tumorigenesis by inducing global DNA hypermethylation that silences cyclin-dependent kinase inhibitors [PMID:22438986]. PIWIL1 expression confers stem-like and oncogenic phenotypes across multiple tumor types, including sarcoma, endometrial, and hepatocellular carcinoma, where it also reshapes tumor metabolism and the immune microenvironment [PMID:22438986, PMID:33633112, PMID:26506848].","teleology":[{"year":2002,"claim":"Established the first cellular context for human PIWIL1 — germline-restricted expression and a growth-suppressive/pro-apoptotic activity when ectopically expressed — framing it as a germline developmental regulator.","evidence":"RT-PCR, immunohistochemistry, and overexpression with apoptosis assays in testis and KG1 leukemia cells","pmids":["12037681","11154219"],"confidence":"Medium","gaps":["No molecular mechanism for the apoptotic phenotype","piRNA/effector activity not yet linked"]},{"year":2010,"claim":"Defined a post-translational regulatory layer: PRMT5-installed symmetrical dimethyl-arginines on PIWI proteins create docking sites for Tudor-domain partners.","evidence":"Biochemical methyltransferase assays and co-immunoprecipitation synthesized in review","pmids":["20360382"],"confidence":"Medium","gaps":["Specific Tudor partners of human PIWIL1 not individually mapped here","Functional consequence of each interaction unresolved"]},{"year":2017,"claim":"Showed an exception to the methylation paradigm — TDRD2 recognizes unmethylated PIWIL1 — and linked this interaction to piRNA biogenesis via 3'-end trimming.","evidence":"Crystal structure, in vitro binding/mutagenesis, and in vitro trimming assay","pmids":["29118143"],"confidence":"High","gaps":["In vivo requirement for trimming in mammals not tested here","Trimming nuclease identity not addressed"]},{"year":2022,"claim":"Resolved how PIWIL1 becomes catalytically competent — GTSF1 converts its weak intrinsic slicer activity into efficient cleavage — and tied this catalysis to fertility.","evidence":"In vitro cleavage reconstitution with GTSF1 plus mouse knockout fertility phenotypes","pmids":["35772669"],"confidence":"High","gaps":["Structural basis of GTSF1 potentiation not defined here","Somatic relevance of catalysis untested"]},{"year":2023,"claim":"Explained why PIWI silencing is broad — PIWIL1 cleaves partially paired targets without requiring seed pairing, distinguishing it mechanistically from AGO Argonautes.","evidence":"In vitro binding and cleavage with recombinant mouse MIWI and sponge PIWI, mutational pairing analysis","pmids":["37344600"],"confidence":"High","gaps":["Target repertoire in vivo not enumerated","Off-target consequences of mismatch tolerance unexamined"]},{"year":2024,"claim":"Provided the structural basis for mismatch tolerance — a wider channel, prearranged extended seed, and a vertebrate-specific lysine that relaxes the seed gate on target binding.","evidence":"Cryo-EM of MILI/HILI piRISCs with functional mutagenesis and in vitro assays","pmids":["38658622"],"confidence":"High","gaps":["Direct structures of PIWIL1 itself not solved here","Catalytic step structures not captured"]},{"year":2015,"claim":"Connected human germline PIWIL1 to its presumed ancestral function — transposon (LINE-1) silencing — across testis and oocytes of multiple species.","evidence":"Immunolocalization, laser-microdissection RT-PCR, proteomics, and small RNA sequencing in human and bovine gonads","pmids":["28676534","25818294"],"confidence":"Medium","gaps":["Causality between PIWIL1 and LINE-1 silencing correlative in human tissue","piRNA target sites not mapped"]},{"year":2023,"claim":"Demonstrated an essential, non-redundant reproductive requirement for PIWIL1 in a mammalian model with full PIWI-family coverage, including partial compensation for PIWIL3.","evidence":"CRISPR knockout of all four PIWI genes in golden hamster with fertility, localization, and RNA-seq analysis","pmids":["37644029"],"confidence":"High","gaps":["Human germline phenotype inferred, not directly tested","Molecular targets driving sterility not fully defined"]},{"year":2012,"claim":"Opened the somatic-oncogenic chapter, linking PIWIL1 to tumorigenesis through global DNA hypermethylation and CDKI silencing reversible with DNMT inhibitors.","evidence":"In vitro differentiation, transgenic mouse sarcoma model, inducible knockdown, and DNA methylation analysis","pmids":["22438986"],"confidence":"High","gaps":["Direct molecular link between PIWIL1 and DNMT machinery not established","piRNA dependence not tested here"]},{"year":2015,"claim":"Identified a piRNA-independent protein-stabilization mechanism — PIWIL1 binds Stathmin1, blocking its ubiquitination and phosphorylation to destabilize microtubules and drive migration.","evidence":"Co-IP, ubiquitination/phosphorylation assays, microtubule polymerization, and migration assays","pmids":["26317901"],"confidence":"Medium","gaps":["Single lab without structural definition of the interaction","Tissue generality of the mechanism unknown"]},{"year":2020,"claim":"Formally separated PIWIL1's somatic oncogenic activity from its piRNA-binding function, implicating the UPF1/NMD pathway in gastric cancer.","evidence":"PIWIL1 knockout, RNA deep sequencing, piRNA-binding mutant rescue, and Co-IP with NMD factors","pmids":["32848063"],"confidence":"High","gaps":["How PIWIL1 modulates NMD activity mechanistically unresolved","mRNA targets stabilized/destabilized not fully cataloged"]},{"year":2021,"claim":"Extended the somatic mRNA-regulatory model to glioma stem cells, where PIWIL1 controls stability of BTG2, FBXW7, and CDKN1B to sustain self-renewal.","evidence":"shRNA knockdown, RNA-seq, mRNA stability assays, and xenograft models","pmids":["33406417"],"confidence":"Medium","gaps":["Direct PIWIL1–mRNA binding not demonstrated for each target","Single lab"]},{"year":2021,"claim":"Broadened PIWIL1's tumor roles to metabolic reprogramming and immune evasion in hepatocellular carcinoma via C3-mediated MDSC recruitment.","evidence":"Overexpression/knockdown, metabolic flux analysis, MDSC co-culture, C3 neutralization, and p38 MAPK inhibition","pmids":["33633112"],"confidence":"Medium","gaps":["Mechanism by which PIWIL1 induces C3 secretion unknown","Single lab"]},{"year":2019,"claim":"Documented a residual piRNA-loaded, perinuclear nuage-like PIWIL1 complex in somatic cancer cells engaging carcinogenesis-related target mRNAs.","evidence":"Immunofluorescence, RNA immunoprecipitation, and RNA sequencing in colorectal cancer cells","pmids":["31694219","33389678"],"confidence":"Medium","gaps":["Functional contribution of these piRNA-mRNA complexes versus piRNA-independent activity unclear","Cleavage versus binding not distinguished"]},{"year":null,"claim":"How PIWIL1 switches between germline piRNA-guided slicing and its diverse piRNA-independent somatic functions — and what determines target selection in each mode — remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying mechanism linking NMD modulation, mRNA stabilization, Stathmin1 binding, and DNA hypermethylation","No structure of human PIWIL1 in either germline or somatic complexes","Direct molecular bridge to DNA methylation machinery unidentified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[4,5,6]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[3,12,14]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[4,5]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,12]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[12]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[4,5,7]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[4,16,17]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[7,9,10]}],"complexes":["piRISC"],"partners":["GTSF1","TDRD2","PRMT5","UPF1","STMN1","HENMT1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96J94","full_name":"Piwi-like protein 1","aliases":[],"length_aa":861,"mass_kda":98.6,"function":"Endoribonuclease that plays a central role in postnatal germ cells by repressing transposable elements and preventing their mobilization, which is essential for the germline integrity. Acts via the piRNA metabolic process, which mediates the repression of transposable elements during meiosis by forming complexes composed of piRNAs and Piwi proteins and governs the methylation and subsequent repression of transposons. Directly binds methylated piRNAs, a class of 24 to 30 nucleotide RNAs that are generated by a Dicer-independent mechanism and are primarily derived from transposons and other repeated sequence elements. Strongly prefers a uridine in the first position of their guide (g1U preference, also named 1U-bias). Not involved in the piRNA amplification loop, also named ping-pong amplification cycle. Acts as an endoribonuclease that cleaves transposon messenger RNAs. Besides their function in transposable elements repression, piRNAs are probably involved in other processes during meiosis such as translation regulation. Probable component of some RISC complex, which mediates RNA cleavage and translational silencing. Also plays a role in the formation of chromatoid bodies and is required for some miRNAs stability. Required to sequester RNF8 in the cytoplasm until late spermatogenesis; RNF8 being released upon ubiquitination and degradation of PIWIL1 May be a negative developmental regulator (PubMed:12037681, PubMed:16287078)","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q96J94/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PIWIL1","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PIWIL1","total_profiled":1310},"omim":[{"mim_id":"619529","title":"PARN-LIKE RIBONUCLEASE DOMAIN-CONTAINING EXONUCLEASE 1; PNLDC1","url":"https://www.omim.org/entry/619529"},{"mim_id":"619528","title":"SPERMATOGENIC FAILURE 57; SPGF57","url":"https://www.omim.org/entry/619528"},{"mim_id":"617748","title":"TUDOR DOMAIN-CONTAINING PROTEIN 5; TDRD5","url":"https://www.omim.org/entry/617748"},{"mim_id":"614960","title":"PHOSPHOLIPASE D FAMILY, MEMBER 6; PLD6","url":"https://www.omim.org/entry/614960"},{"mim_id":"610315","title":"PIWI-LIKE RNA-MEDIATED GENE SILENCING 4; PIWIL4","url":"https://www.omim.org/entry/610315"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"testis","ntpm":39.9}],"url":"https://www.proteinatlas.org/search/PIWIL1"},"hgnc":{"alias_symbol":["PIWI","HIWI","CT80.1"],"prev_symbol":[]},"alphafold":{"accession":"Q96J94","domains":[{"cath_id":"3.30.70","chopping":"129-201","consensus_level":"medium","plddt":92.2034,"start":129,"end":201},{"cath_id":"2.170.260.10","chopping":"210-396","consensus_level":"high","plddt":88.6179,"start":210,"end":396},{"cath_id":"3.40.50.2300","chopping":"490-611","consensus_level":"high","plddt":95.4475,"start":490,"end":611},{"cath_id":"3.30.420.10","chopping":"617-853","consensus_level":"medium","plddt":93.3108,"start":617,"end":853}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96J94","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96J94-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96J94-F1-predicted_aligned_error_v6.png","plddt_mean":85.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PIWIL1","jax_strain_url":"https://www.jax.org/strain/search?query=PIWIL1"},"sequence":{"accession":"Q96J94","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96J94.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96J94/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96J94"}},"corpus_meta":[{"pmid":"30446728","id":"PMC_30446728","title":"PIWI-interacting RNAs: small RNAs with big functions.","date":"2019","source":"Nature reviews. Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30446728","citation_count":853,"is_preprint":false},{"pmid":"17975059","id":"PMC_17975059","title":"The Piwi-piRNA pathway provides an adaptive defense in the transposon arms race.","date":"2007","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/17975059","citation_count":808,"is_preprint":false},{"pmid":"25747396","id":"PMC_25747396","title":"PIWI-Interacting RNA: Its Biogenesis and Functions.","date":"2015","source":"Annual review of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25747396","citation_count":552,"is_preprint":false},{"pmid":"19575643","id":"PMC_19575643","title":"The biogenesis and function of PIWI proteins and piRNAs: progress and prospect.","date":"2009","source":"Annual review of cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/19575643","citation_count":413,"is_preprint":false},{"pmid":"24429634","id":"PMC_24429634","title":"PIWI proteins and PIWI-interacting RNAs in the soma.","date":"2014","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/24429634","citation_count":330,"is_preprint":false},{"pmid":"21942366","id":"PMC_21942366","title":"Uniting germline and stem cells: the function of Piwi proteins and the piRNA pathway in diverse organisms.","date":"2011","source":"Annual review of genetics","url":"https://pubmed.ncbi.nlm.nih.gov/21942366","citation_count":294,"is_preprint":false},{"pmid":"31399034","id":"PMC_31399034","title":"The emerging role of the piRNA/piwi complex in cancer.","date":"2019","source":"Molecular cancer","url":"https://pubmed.ncbi.nlm.nih.gov/31399034","citation_count":271,"is_preprint":false},{"pmid":"23797853","id":"PMC_23797853","title":"PIWI-interacting RNAs: from generation to transgenerational epigenetics.","date":"2013","source":"Nature reviews. Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23797853","citation_count":256,"is_preprint":false},{"pmid":"12037681","id":"PMC_12037681","title":"Molecular characterization of hiwi, a human member of the piwi gene family whose overexpression is correlated to seminomas.","date":"2002","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/12037681","citation_count":243,"is_preprint":false},{"pmid":"36104626","id":"PMC_36104626","title":"Emerging roles and functional mechanisms of PIWI-interacting RNAs.","date":"2022","source":"Nature reviews. Molecular cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/36104626","citation_count":217,"is_preprint":false},{"pmid":"25818294","id":"PMC_25818294","title":"Piwi proteins and piRNAs in mammalian oocytes and early embryos.","date":"2015","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/25818294","citation_count":182,"is_preprint":false},{"pmid":"11154219","id":"PMC_11154219","title":"Human CD34(+) stem cells express the hiwi gene, a human homologue of the Drosophila gene piwi.","date":"2001","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/11154219","citation_count":169,"is_preprint":false},{"pmid":"20360382","id":"PMC_20360382","title":"How does the royal family of Tudor rule the PIWI-interacting RNA pathway?","date":"2010","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/20360382","citation_count":159,"is_preprint":false},{"pmid":"16287078","id":"PMC_16287078","title":"Expression of hiwi gene in human gastric cancer was associated with proliferation of cancer cells.","date":"2006","source":"International journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/16287078","citation_count":152,"is_preprint":false},{"pmid":"24367095","id":"PMC_24367095","title":"PIWI proteins and PIWI-interacting RNAs function in Hydra somatic stem cells.","date":"2013","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/24367095","citation_count":127,"is_preprint":false},{"pmid":"21928326","id":"PMC_21928326","title":"Piwis and piwi-interacting RNAs in the epigenetics of cancer.","date":"2012","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21928326","citation_count":125,"is_preprint":false},{"pmid":"23087701","id":"PMC_23087701","title":"PIWI Expression and Function in Cancer.","date":"2012","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23087701","citation_count":118,"is_preprint":false},{"pmid":"29130960","id":"PMC_29130960","title":"PIWI Proteins and PIWI-Interacting RNA: Emerging Roles in Cancer.","date":"2017","source":"Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/29130960","citation_count":111,"is_preprint":false},{"pmid":"23465540","id":"PMC_23465540","title":"Beyond transposons: the epigenetic and somatic functions of the Piwi-piRNA mechanism.","date":"2013","source":"Current opinion in cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/23465540","citation_count":111,"is_preprint":false},{"pmid":"16953229","id":"PMC_16953229","title":"Expression of the stem cell self-renewal gene Hiwi and risk of tumour-related death in patients with soft-tissue sarcoma.","date":"2006","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/16953229","citation_count":108,"is_preprint":false},{"pmid":"18781170","id":"PMC_18781170","title":"The stem cell-associated Hiwi gene in human adenocarcinoma of the pancreas: expression and risk of tumour-related death.","date":"2008","source":"British journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/18781170","citation_count":103,"is_preprint":false},{"pmid":"29281264","id":"PMC_29281264","title":"PIWI-Interacting RNA in Drosophila: Biogenesis, Transposon Regulation, and Beyond.","date":"2017","source":"Chemical reviews","url":"https://pubmed.ncbi.nlm.nih.gov/29281264","citation_count":93,"is_preprint":false},{"pmid":"23712694","id":"PMC_23712694","title":"Untangling the web: the diverse functions of the PIWI/piRNA pathway.","date":"2013","source":"Molecular reproduction and development","url":"https://pubmed.ncbi.nlm.nih.gov/23712694","citation_count":86,"is_preprint":false},{"pmid":"37344600","id":"PMC_37344600","title":"Relaxed targeting rules help PIWI proteins silence transposons.","date":"2023","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/37344600","citation_count":73,"is_preprint":false},{"pmid":"32848063","id":"PMC_32848063","title":"PIWIL1 promotes gastric cancer via a piRNA-independent mechanism.","date":"2020","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/32848063","citation_count":70,"is_preprint":false},{"pmid":"34118972","id":"PMC_34118972","title":"The biogenesis and biological function of PIWI-interacting RNA in cancer.","date":"2021","source":"Journal of hematology & oncology","url":"https://pubmed.ncbi.nlm.nih.gov/34118972","citation_count":65,"is_preprint":false},{"pmid":"22438986","id":"PMC_22438986","title":"Hiwi mediated tumorigenesis is associated with DNA hypermethylation.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22438986","citation_count":64,"is_preprint":false},{"pmid":"36882835","id":"PMC_36882835","title":"The epigenetic regulatory mechanism of PIWI/piRNAs in human cancers.","date":"2023","source":"Molecular cancer","url":"https://pubmed.ncbi.nlm.nih.gov/36882835","citation_count":62,"is_preprint":false},{"pmid":"32951946","id":"PMC_32951946","title":"Functions of PIWI Proteins in Gene Regulation: New Arrows Added to the piRNA Quiver.","date":"2020","source":"Trends in genetics : TIG","url":"https://pubmed.ncbi.nlm.nih.gov/32951946","citation_count":61,"is_preprint":false},{"pmid":"32051406","id":"PMC_32051406","title":"Crystal structure of Drosophila Piwi.","date":"2020","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/32051406","citation_count":57,"is_preprint":false},{"pmid":"27067666","id":"PMC_27067666","title":"Abundant and Altered Expression of PIWI-Interacting RNAs during Cardiac Hypertrophy.","date":"2016","source":"Heart, lung & circulation","url":"https://pubmed.ncbi.nlm.nih.gov/27067666","citation_count":57,"is_preprint":false},{"pmid":"31838836","id":"PMC_31838836","title":"PIWI Proteins and piRNAs in the Nervous System.","date":"2019","source":"Molecules and cells","url":"https://pubmed.ncbi.nlm.nih.gov/31838836","citation_count":56,"is_preprint":false},{"pmid":"34626567","id":"PMC_34626567","title":"Terminal modification, sequence, length, and PIWI-protein identity determine piRNA stability.","date":"2021","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/34626567","citation_count":55,"is_preprint":false},{"pmid":"33633112","id":"PMC_33633112","title":"PIWIL1 governs the crosstalk of cancer cell metabolism and immunosuppressive microenvironment in hepatocellular carcinoma.","date":"2021","source":"Signal transduction and targeted therapy","url":"https://pubmed.ncbi.nlm.nih.gov/33633112","citation_count":54,"is_preprint":false},{"pmid":"31303794","id":"PMC_31303794","title":"The emerging roles of PIWI-interacting RNA in human cancers.","date":"2019","source":"Cancer management and research","url":"https://pubmed.ncbi.nlm.nih.gov/31303794","citation_count":51,"is_preprint":false},{"pmid":"35772669","id":"PMC_35772669","title":"GTSF1 accelerates target RNA cleavage by PIWI-clade Argonaute proteins.","date":"2022","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/35772669","citation_count":50,"is_preprint":false},{"pmid":"22996918","id":"PMC_22996918","title":"Concise review: The Piwi-piRNA axis: pivotal beyond transposon silencing.","date":"2012","source":"Stem cells (Dayton, Ohio)","url":"https://pubmed.ncbi.nlm.nih.gov/22996918","citation_count":50,"is_preprint":false},{"pmid":"33406417","id":"PMC_33406417","title":"Piwil1 Regulates Glioma Stem Cell Maintenance and Glioblastoma Progression.","date":"2021","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/33406417","citation_count":49,"is_preprint":false},{"pmid":"31183996","id":"PMC_31183996","title":"PIWI pathway against viruses in insects.","date":"2019","source":"Wiley interdisciplinary reviews. RNA","url":"https://pubmed.ncbi.nlm.nih.gov/31183996","citation_count":48,"is_preprint":false},{"pmid":"25269862","id":"PMC_25269862","title":"Silencing HIWI suppresses the growth, invasion and migration of glioma cells.","date":"2014","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/25269862","citation_count":48,"is_preprint":false},{"pmid":"25119492","id":"PMC_25119492","title":"Hiwi facilitates chemoresistance as a cancer stem cell marker in cervical cancer.","date":"2014","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/25119492","citation_count":48,"is_preprint":false},{"pmid":"24948137","id":"PMC_24948137","title":"Piwi and potency: PIWI proteins in animal stem cells and regeneration.","date":"2014","source":"Integrative and comparative biology","url":"https://pubmed.ncbi.nlm.nih.gov/24948137","citation_count":47,"is_preprint":false},{"pmid":"29168346","id":"PMC_29168346","title":"Cancer-testis gene PIWIL1 promotes cell proliferation, migration, and invasion in lung adenocarcinoma.","date":"2017","source":"Cancer medicine","url":"https://pubmed.ncbi.nlm.nih.gov/29168346","citation_count":44,"is_preprint":false},{"pmid":"26506848","id":"PMC_26506848","title":"Stem cell protein Piwil1 endowed endometrial cancer cells with stem-like properties via inducing epithelial-mesenchymal transition.","date":"2015","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/26506848","citation_count":39,"is_preprint":false},{"pmid":"32697419","id":"PMC_32697419","title":"Role of PIWI-interacting RNAs on cell survival: Proliferation, apoptosis, and cycle.","date":"2020","source":"IUBMB life","url":"https://pubmed.ncbi.nlm.nih.gov/32697419","citation_count":38,"is_preprint":false},{"pmid":"28653810","id":"PMC_28653810","title":"The Piwi-piRNA pathway: road to immortality.","date":"2017","source":"Aging cell","url":"https://pubmed.ncbi.nlm.nih.gov/28653810","citation_count":37,"is_preprint":false},{"pmid":"25370791","id":"PMC_25370791","title":"Hiwi downregulation, mediated by shRNA, reduces the proliferation and migration of human hepatocellular carcinoma cells.","date":"2014","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/25370791","citation_count":37,"is_preprint":false},{"pmid":"20502058","id":"PMC_20502058","title":"Expression of PSCA, PIWIL1, and TBX2 in endometrial adenocarcinoma.","date":"2010","source":"Onkologie","url":"https://pubmed.ncbi.nlm.nih.gov/20502058","citation_count":37,"is_preprint":false},{"pmid":"28676534","id":"PMC_28676534","title":"Expression patterns of HENMT1 and PIWIL1 in human testis: implications for transposon expression.","date":"2017","source":"Reproduction (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/28676534","citation_count":37,"is_preprint":false},{"pmid":"38198029","id":"PMC_38198029","title":"The burgeoning importance of PIWI-interacting RNAs in cancer progression.","date":"2023","source":"Science China. Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/38198029","citation_count":36,"is_preprint":false},{"pmid":"28842123","id":"PMC_28842123","title":"MiRNA-154-5p inhibits cell proliferation and metastasis by targeting PIWIL1 in glioblastoma.","date":"2017","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/28842123","citation_count":35,"is_preprint":false},{"pmid":"25292027","id":"PMC_25292027","title":"Overexpression of hiwi promotes growth of human breast cancer cells.","date":"2014","source":"Asian Pacific journal of cancer prevention : APJCP","url":"https://pubmed.ncbi.nlm.nih.gov/25292027","citation_count":34,"is_preprint":false},{"pmid":"29580825","id":"PMC_29580825","title":"PIWI-piRNA pathway: Setting the pace of aging by reducing DNA damage.","date":"2018","source":"Mechanisms of ageing and development","url":"https://pubmed.ncbi.nlm.nih.gov/29580825","citation_count":32,"is_preprint":false},{"pmid":"32877760","id":"PMC_32877760","title":"PIWI-interacting RNAs in human cancer.","date":"2020","source":"Seminars in cancer biology","url":"https://pubmed.ncbi.nlm.nih.gov/32877760","citation_count":31,"is_preprint":false},{"pmid":"33389678","id":"PMC_33389678","title":"PIWIL1 interacting RNA piR-017061 inhibits pancreatic cancer growth via regulating EFNA5.","date":"2021","source":"Human cell","url":"https://pubmed.ncbi.nlm.nih.gov/33389678","citation_count":31,"is_preprint":false},{"pmid":"30226604","id":"PMC_30226604","title":"Epigenetic roles of PIWI‑interacting RNAs (piRNAs) in cancer metastasis (Review).","date":"2018","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/30226604","citation_count":31,"is_preprint":false},{"pmid":"38303021","id":"PMC_38303021","title":"Critical appraisal of the piRNA-PIWI axis in cancer and cancer stem cells.","date":"2024","source":"Biomarker research","url":"https://pubmed.ncbi.nlm.nih.gov/38303021","citation_count":31,"is_preprint":false},{"pmid":"25791297","id":"PMC_25791297","title":"Piwi-pathway alteration induces LINE-1 transposon derepression and infertility development in cryptorchidism.","date":"2015","source":"Sexual development : genetics, molecular biology, evolution, endocrinology, embryology, and pathology of sex determination and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/25791297","citation_count":31,"is_preprint":false},{"pmid":"31478570","id":"PMC_31478570","title":"PIWI-interacting RNA 39980 promotes tumor progression and reduces drug sensitivity in neuroblastoma cells.","date":"2019","source":"Journal of cellular physiology","url":"https://pubmed.ncbi.nlm.nih.gov/31478570","citation_count":31,"is_preprint":false},{"pmid":"34295823","id":"PMC_34295823","title":"Piwi-Interacting RNAs: A New Class of Regulator in Human Breast Cancer.","date":"2021","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/34295823","citation_count":31,"is_preprint":false},{"pmid":"20204292","id":"PMC_20204292","title":"The universal overexpression of a cancer testis antigen hiwi is associated with cancer angiogenesis.","date":"2010","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/20204292","citation_count":30,"is_preprint":false},{"pmid":"29118143","id":"PMC_29118143","title":"Structural basis for arginine methylation-independent recognition of PIWIL1 by TDRD2.","date":"2017","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/29118143","citation_count":30,"is_preprint":false},{"pmid":"34681826","id":"PMC_34681826","title":"A Review of Discovery Profiling of PIWI-Interacting RNAs and Their Diverse Functions in Metazoans.","date":"2021","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/34681826","citation_count":30,"is_preprint":false},{"pmid":"38031146","id":"PMC_38031146","title":"Novel roles of PIWI proteins and PIWI-interacting RNAs in human health and diseases.","date":"2023","source":"Cell communication and signaling : CCS","url":"https://pubmed.ncbi.nlm.nih.gov/38031146","citation_count":28,"is_preprint":false},{"pmid":"37076042","id":"PMC_37076042","title":"PIWI-interacting RNAs: Critical roles and therapeutic targets in cancer.","date":"2023","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/37076042","citation_count":27,"is_preprint":false},{"pmid":"36835756","id":"PMC_36835756","title":"What Are the Functional Roles of Piwi Proteins and piRNAs in Insects?","date":"2023","source":"Insects","url":"https://pubmed.ncbi.nlm.nih.gov/36835756","citation_count":27,"is_preprint":false},{"pmid":"38258575","id":"PMC_38258575","title":"AVCAPIR: A Novel Procalcific PIWI-Interacting RNA in Calcific Aortic Valve Disease.","date":"2024","source":"Circulation","url":"https://pubmed.ncbi.nlm.nih.gov/38258575","citation_count":25,"is_preprint":false},{"pmid":"38658622","id":"PMC_38658622","title":"Mammalian PIWI-piRNA-target complexes reveal features for broad and efficient target silencing.","date":"2024","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/38658622","citation_count":25,"is_preprint":false},{"pmid":"27893851","id":"PMC_27893851","title":"Expression and Regulation of PIWIL-Proteins and PIWI-Interacting RNAs in Rheumatoid Arthritis.","date":"2016","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/27893851","citation_count":25,"is_preprint":false},{"pmid":"30965112","id":"PMC_30965112","title":"Disrupting the hippocampal Piwi pathway enhances contextual fear memory in mice.","date":"2019","source":"Neurobiology of learning and memory","url":"https://pubmed.ncbi.nlm.nih.gov/30965112","citation_count":25,"is_preprint":false},{"pmid":"26026091","id":"PMC_26026091","title":"Correlation of HIWI and HILI Expression with Cancer Stem Cell Markers in Colorectal Cancer.","date":"2015","source":"Anticancer research","url":"https://pubmed.ncbi.nlm.nih.gov/26026091","citation_count":24,"is_preprint":false},{"pmid":"30304932","id":"PMC_30304932","title":"Transposons and the PIWI pathway: genome defense in gametes and embryos.","date":"2018","source":"Reproduction (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/30304932","citation_count":24,"is_preprint":false},{"pmid":"32075940","id":"PMC_32075940","title":"PIWI-piRNA pathway-mediated transposable element repression in Hydra somatic stem cells.","date":"2020","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/32075940","citation_count":24,"is_preprint":false},{"pmid":"22591718","id":"PMC_22591718","title":"RASSF1C modulates the expression of a stem cell renewal gene, PIWIL1.","date":"2012","source":"BMC research notes","url":"https://pubmed.ncbi.nlm.nih.gov/22591718","citation_count":24,"is_preprint":false},{"pmid":"23621188","id":"PMC_23621188","title":"Hiwi knockdown inhibits the growth of lung cancer in nude mice.","date":"2013","source":"Asian Pacific journal of cancer prevention : APJCP","url":"https://pubmed.ncbi.nlm.nih.gov/23621188","citation_count":24,"is_preprint":false},{"pmid":"34291132","id":"PMC_34291132","title":"PIWI-interacting RNAs: Mitochondria-based biogenesis and functions in cancer.","date":"2020","source":"Genes & diseases","url":"https://pubmed.ncbi.nlm.nih.gov/34291132","citation_count":23,"is_preprint":false},{"pmid":"29317647","id":"PMC_29317647","title":"Investigation of piwi-interacting RNA pathway genes role in idiopathic non-obstructive azoospermia.","date":"2018","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/29317647","citation_count":23,"is_preprint":false},{"pmid":"31694219","id":"PMC_31694219","title":"Molecular and Functional Characterization of the Somatic PIWIL1/piRNA Pathway in Colorectal Cancer Cells.","date":"2019","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/31694219","citation_count":22,"is_preprint":false},{"pmid":"22952772","id":"PMC_22952772","title":"Altered expression of porcine Piwi genes and piRNA during development.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22952772","citation_count":22,"is_preprint":false},{"pmid":"29599319","id":"PMC_29599319","title":"Aberrant Expression of PIWIL1 and PIWIL2 and Their Clinical Significance in Ductal Breast Carcinoma.","date":"2018","source":"Anticancer research","url":"https://pubmed.ncbi.nlm.nih.gov/29599319","citation_count":21,"is_preprint":false},{"pmid":"28844648","id":"PMC_28844648","title":"Drosophila PAF1 Modulates PIWI/piRNA Silencing Capacity.","date":"2017","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/28844648","citation_count":21,"is_preprint":false},{"pmid":"29516567","id":"PMC_29516567","title":"Investigating piwi-interacting RNA regulome in human neuroblastoma.","date":"2018","source":"Genes, chromosomes & cancer","url":"https://pubmed.ncbi.nlm.nih.gov/29516567","citation_count":21,"is_preprint":false},{"pmid":"35155584","id":"PMC_35155584","title":"PIWI-Interacting RNAs (piRNAs): Promising Applications as Emerging Biomarkers for Digestive System Cancer.","date":"2022","source":"Frontiers in molecular biosciences","url":"https://pubmed.ncbi.nlm.nih.gov/35155584","citation_count":21,"is_preprint":false},{"pmid":"26355242","id":"PMC_26355242","title":"Hiwi Promotes the Proliferation of Colorectal Cancer Cells via Upregulating Global DNA Methylation.","date":"2015","source":"Disease markers","url":"https://pubmed.ncbi.nlm.nih.gov/26355242","citation_count":21,"is_preprint":false},{"pmid":"35015250","id":"PMC_35015250","title":"piRNA/PIWI Protein Complex as a Potential Biomarker in Sporadic Amyotrophic Lateral Sclerosis.","date":"2022","source":"Molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/35015250","citation_count":21,"is_preprint":false},{"pmid":"33718392","id":"PMC_33718392","title":"Critical Roles of PIWIL1 in Human Tumors: Expression, Functions, Mechanisms, and Potential Clinical Implications.","date":"2021","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/33718392","citation_count":20,"is_preprint":false},{"pmid":"29164638","id":"PMC_29164638","title":"The PIWI-Interacting RNA Molecular Pathway: Insights From Cultured Silkworm Germline Cells.","date":"2017","source":"BioEssays : news and reviews in molecular, cellular and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/29164638","citation_count":20,"is_preprint":false},{"pmid":"31890151","id":"PMC_31890151","title":"Epigenetic roles of PIWI proteins and piRNAs in lung cancer.","date":"2019","source":"Cell & bioscience","url":"https://pubmed.ncbi.nlm.nih.gov/31890151","citation_count":20,"is_preprint":false},{"pmid":"33109195","id":"PMC_33109195","title":"PIWI-interacting RNAs and PIWI proteins in glioma: molecular pathogenesis and role as biomarkers.","date":"2020","source":"Cell communication and signaling : CCS","url":"https://pubmed.ncbi.nlm.nih.gov/33109195","citation_count":19,"is_preprint":false},{"pmid":"21327579","id":"PMC_21327579","title":"Expression of HIWI in human hepatocellular carcinoma.","date":"2011","source":"Cell biochemistry and biophysics","url":"https://pubmed.ncbi.nlm.nih.gov/21327579","citation_count":19,"is_preprint":false},{"pmid":"37503320","id":"PMC_37503320","title":"PIWIL1 interacting RNA piR-017724 inhibits proliferation, invasion, and migration, and inhibits the development of HCC by silencing PLIN3.","date":"2023","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/37503320","citation_count":19,"is_preprint":false},{"pmid":"34336834","id":"PMC_34336834","title":"Knockout Gene-Based Evidence for PIWI-Interacting RNA Pathway in Mammals.","date":"2021","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/34336834","citation_count":18,"is_preprint":false},{"pmid":"37783675","id":"PMC_37783675","title":"PIWI-interacting RNA expression regulates pathogenesis in a Caenorhabditis elegans model of Lewy body disease.","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/37783675","citation_count":18,"is_preprint":false},{"pmid":"32992598","id":"PMC_32992598","title":"Diverse Defenses: A Perspective Comparing Dipteran Piwi-piRNA Pathways.","date":"2020","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/32992598","citation_count":18,"is_preprint":false},{"pmid":"32843637","id":"PMC_32843637","title":"DEPS-1 is required for piRNA-dependent silencing and PIWI condensate organisation in Caenorhabditis elegans.","date":"2020","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/32843637","citation_count":18,"is_preprint":false},{"pmid":"37644029","id":"PMC_37644029","title":"The non-redundant functions of PIWI family proteins in gametogenesis in golden hamsters.","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/37644029","citation_count":17,"is_preprint":false},{"pmid":"34212832","id":"PMC_34212832","title":"PiWi RNA in Neurodevelopment and Neurodegenerative Disorders.","date":"2022","source":"Current molecular pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/34212832","citation_count":17,"is_preprint":false},{"pmid":"26317901","id":"PMC_26317901","title":"PIWIL1 destabilizes microtubule by suppressing phosphorylation at Ser16 and RLIM-mediated degradation of Stathmin1.","date":"2015","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/26317901","citation_count":17,"is_preprint":false},{"pmid":"33213873","id":"PMC_33213873","title":"Effects of fluoride on PIWI-interacting RNA expression profiling in testis of mice.","date":"2020","source":"Chemosphere","url":"https://pubmed.ncbi.nlm.nih.gov/33213873","citation_count":17,"is_preprint":false},{"pmid":"35931391","id":"PMC_35931391","title":"Emerging roles of PIWI-interacting RNAs (piRNAs) and PIWI proteins in head and neck cancer and their potential clinical implications.","date":"2022","source":"Biochimica et biophysica acta. Reviews on cancer","url":"https://pubmed.ncbi.nlm.nih.gov/35931391","citation_count":17,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":43779,"output_tokens":5573,"usd":0.107466,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14120,"output_tokens":4431,"usd":0.090688,"stage2_stop_reason":"end_turn"},"total_usd":0.198154,"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\": 2002,\n      \"finding\": \"HIWI (PIWIL1) protein is specifically expressed in germline cells of the human testis, detectable in spermatocytes and round spermatids during spermatogenesis, and its transient overexpression in the human leukemia cell line KG1 caused a dramatic reduction in cellular proliferation and induced programmed cell death (Annexin V assay), suggesting a role as a negative developmental regulator.\",\n      \"method\": \"RT-PCR, immunohistochemistry, transient transfection overexpression, Annexin V apoptosis assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single lab, multiple methods (IHC, overexpression, apoptosis assay) but no pathway-level mechanistic dissection\",\n      \"pmids\": [\"12037681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"HIWI (PIWIL1) is expressed in human CD34+ hematopoietic progenitor/stem cells but not in more differentiated cell populations; overexpression in KG1 cells reduced proliferation and induced apoptosis, implicating HIWI in stem cell self-renewal regulation.\",\n      \"method\": \"RT-PCR, 5' RACE cloning, transient transfection, cell proliferation assay, Annexin V apoptosis assay\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single lab, multiple orthogonal methods (expression, overexpression, apoptosis assay), but limited mechanistic pathway placement\",\n      \"pmids\": [\"11154219\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"PIWI proteins (including PIWIL1/HIWI) contain symmetrical dimethyl arginines (sDMAs) installed by the methyltransferase PRMT5 (Dart5/Capsuleen), and this modification mediates interaction with multiple Tudor (Tud) domain family proteins through sDMA-binding Tudor domains.\",\n      \"method\": \"Biochemical analysis, methyltransferase assays, co-immunoprecipitation, review of prior experimental findings\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — based on synthesis of prior experimental results (reciprocal Co-IP, biochemical assays from multiple labs) described in this review\",\n      \"pmids\": [\"20360382\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The extended Tudor domain of mammalian TDRD2 preferentially recognizes an unmethylated arginine-rich sequence from PIWIL1, in contrast to most Tudor domains that bind methylated PIWI proteins. Structural studies revealed that the interface of Tudor and staphylococcal nuclease domains mediates PIWIL1 peptide recognition. Mutations disrupting the TDRD2-PIWIL1 interaction compromised piRNA maturation via 3'-end trimming in vitro.\",\n      \"method\": \"Crystal structure determination, in vitro binding assays, mutagenesis, in vitro trimming assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with mutagenesis and in vitro functional validation in a single rigorous study\",\n      \"pmids\": [\"29118143\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"GTSF1 potentiates the weak intrinsic piRNA-directed RNA cleavage activity of PIWI proteins including MIWI (PIWIL1), transforming them into efficient endoribonucleases. The piRNA-guided endoribonuclease activities of MIWI (PIWIL1) and MILI are essential for the production of functional sperm.\",\n      \"method\": \"In vitro cleavage assay, biochemical reconstitution, mouse knockout phenotype\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of catalytic activity with auxiliary factor, corroborated by mouse KO fertility phenotypes\",\n      \"pmids\": [\"35772669\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Unlike AGO-clade Argonaute proteins, PIWI proteins (tested with mouse MIWI/PIWIL1 and sponge PIWI) efficiently cleave target transcripts that are only partially base-paired to their piRNA guides. PIWI slicing tolerates mismatches to any target nucleotide including those flanking the scissile phosphate, and seed pairing is dispensable for PIWI binding or cleavage, in contrast to AGO proteins.\",\n      \"method\": \"In vitro target binding and cleavage assays with recombinant mouse and sponge PIWI proteins, mutational analysis of target:piRNA pairing\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — rigorous in vitro biochemical reconstitution with multiple orthogonal experiments across two PIWI proteins\",\n      \"pmids\": [\"37344600\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Cryo-EM structural studies of mammalian MILI (PIWIL2) and human HILI piRNA-induced silencing complexes (piRISCs) revealed that they bind and cleave targets more efficiently than invertebrate counterparts, adopt a wider nucleic-acid-binding channel, and display an extended prearranged piRNA seed in the absence of target. A vertebrate-specific lysine distorts the piRNA seed, shifting the trajectory of the piRNA-target duplex, and promotes target binding and cleavage. In the presence of target, the seed gate adopts a relaxed state, enabling PIWI tolerance of seed-target mismatches.\",\n      \"method\": \"Cryo-EM structure determination, in vitro binding and cleavage assays, mutagenesis of vertebrate-specific lysine\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structures with functional mutagenesis and in vitro assays in a single rigorous study; directly characterizes human HILI (PIWIL2) and provides molecular basis applicable to mammalian PIWI clade including PIWIL1\",\n      \"pmids\": [\"38658622\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PIWIL1 is highly expressed in gastric cancer tissues and cell lines. PIWIL1 knockout drastically reduces gastric cancer cell proliferation, migration, metastasis, and tumorigenesis. Surprisingly, few bona fide piRNAs exist in gastric cancer cells, and abolishing the piRNA-binding activity of PIWIL1 does not affect its oncogenic function. PIWIL1 function in gastric cancer involves piRNA-independent interaction with the UPF1-mediated nonsense-mediated mRNA decay (NMD) mechanism.\",\n      \"method\": \"PIWIL1 knockout (PIWIL1-KO), RNA deep sequencing, piRNA-binding mutant functional rescue, co-immunoprecipitation with NMD factors\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with defined proliferative/metastatic phenotype, piRNA-binding mutant used to separate piRNA-dependent from independent functions, biochemical interaction with NMD pathway identified\",\n      \"pmids\": [\"32848063\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PIWIL1 directly binds to Stathmin1, upregulates Stathmin1 expression by inhibiting ubiquitin-mediated degradation induced by the E3 ubiquitin ligase RLIM, and reduces phosphorylation of Stathmin1 at Ser-16 by inhibiting the interaction between CaMKII and Stathmin1. Through these mechanisms PIWIL1 suppresses microtubule polymerization and promotes cell proliferation and migration.\",\n      \"method\": \"Co-immunoprecipitation (direct binding), Western blot, ubiquitination assay, phosphorylation assay, microtubule polymerization assay, cell proliferation and migration assays\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding shown by Co-IP, multiple functional readouts (ubiquitination, phosphorylation, microtubule dynamics), single lab\",\n      \"pmids\": [\"26317901\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Overexpression of HIWI (PIWIL1) in sarcoma precursors inhibits their differentiation in vitro and generates sarcomas in vivo. Transgenic mice expressing mesodermally-restricted Hiwi develop sarcomas. Inducible downregulation of Hiwi in human sarcomas inhibits growth and re-establishes differentiation. Hiwi-associated tumorigenesis is accompanied by increased global DNA methylation and silencing of cyclin-dependent kinase inhibitors (CDKIs), which is reversible with DNA methyltransferase inhibitors.\",\n      \"method\": \"In vitro differentiation assays, transgenic mouse model, inducible knockdown, DNA methylation analysis, DNMT inhibitor treatment\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal in vitro and in vivo models (cell culture, transgenic mice, inducible KD) with mechanistic link to DNA methylation and CDKI silencing\",\n      \"pmids\": [\"22438986\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Piwil1 (HIWI) is enriched in glioma stem-like cells (GSCs) and maintains self-renewal. Silencing Piwil1 in GSCs leads to global gene expression changes resulting in cell-cycle arrest, senescence, or apoptosis. Piwil1 knockdown increases expression of BTG2 and FBXW7 (leading to reduced c-Myc and loss of Olig2/Nestin), and Piwil1 regulates mRNA stability of BTG2, FBXW7, and CDKN1B. In animal models, Piwil1 knockdown suppresses tumor growth.\",\n      \"method\": \"shRNA knockdown, RNA-seq, mRNA stability assay, xenograft mouse models, Western blot\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KD with defined cellular phenotype, RNA-seq, mRNA stability assay, in vivo validation; single lab\",\n      \"pmids\": [\"33406417\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PIWIL1 in HCC increases oxygen consumption and energy production via fatty acid metabolism without altering aerobic glycolysis. PIWIL1-overexpressing HCC cells attract myeloid-derived suppressor cells (MDSCs) into the tumor microenvironment. Complement C3, whose secretion is induced by PIWIL1 in HCC cells, mediates the interaction with MDSCs by activating p38 MAPK signaling in MDSCs, which initiates immunosuppressive IL-10 expression.\",\n      \"method\": \"PIWIL1 overexpression/knockdown, metabolic flux analysis, RNA-seq, MDSC co-culture, C3 neutralization, p38 MAPK inhibition\",\n      \"journal\": \"Signal transduction and targeted therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal functional assays (metabolism, immune cell recruitment, signaling), single lab\",\n      \"pmids\": [\"33633112\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PIWIL1 localizes in a nuage-like perinuclear structure in colorectal cancer (COLO 205) cells. RNA immunoprecipitation revealed piRNAs loaded into PIWIL1 that form complexes also comprising target mRNAs encoding key regulatory proteins involved in colorectal carcinogenesis.\",\n      \"method\": \"Immunofluorescence localization, RNA immunoprecipitation (RIP), piRNA methylation analysis, RNA sequencing\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by immunofluorescence, RIP demonstrating PIWIL1-piRNA-mRNA complex formation; single lab\",\n      \"pmids\": [\"31694219\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"RASSF1C overexpression increases PIWIL1 gene expression in non-small cell lung cancer cells, and RASSF1C silencing decreases PIWIL1 expression. Inhibition of the MEK-ERK1/2 pathway suppresses PIWIL1 expression, suggesting RASSF1C regulates PIWIL1 through activation of the MEK-ERK1/2 pathway.\",\n      \"method\": \"RASSF1C overexpression, siRNA knockdown, Affymetrix microarray, qRT-PCR, Western blot, immunostaining, MEK inhibitor treatment\",\n      \"journal\": \"BMC research notes\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, indirect pathway placement via pharmacological inhibition, no direct mechanistic link between ERK and PIWIL1 promoter\",\n      \"pmids\": [\"22591718\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PIWIL1 interacting with piR-017061 facilitates EFNA5 mRNA degradation in pancreatic cancer cells. Loss of piR-017061 results in EFNA5 accumulation, which promotes pancreatic cancer development. Direct binding between piR-017061 and EFNA5 mRNA is mediated by PIWIL1.\",\n      \"method\": \"RNA immunoprecipitation, qRT-PCR, cell proliferation assay, in vivo xenograft, mRNA stability assay\",\n      \"journal\": \"Human cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RIP demonstrating PIWIL1-piRNA-target mRNA complex, functional in vitro and in vivo validation; single lab\",\n      \"pmids\": [\"33389678\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"HENMT1 and PIWIL1 are coexpressed in pachytene spermatocytes and spermatids in the human testis, and samples expressing HENMT1, PIWIL1, and PIWIL2 showed significantly lower transposon (LINE-1) expression compared to samples without expression, supporting conservation of the transposon-regulating piRNA pathway function in adult human testis.\",\n      \"method\": \"Immunolocalization, RT-PCR after laser microdissection, RT-qPCR in 222 testis biopsies, HENMT1-overexpressing cell lines\",\n      \"journal\": \"Reproduction (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct colocalization, corroborated by functional overexpression data in cell lines and correlation across large tissue sample set\",\n      \"pmids\": [\"28676534\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In golden hamsters, knockout of PIWIL1 leads to female sterility (PIWIL1 is highly expressed throughout oogenesis and early embryogenesis), and PIWIL1 can partially compensate for TE silencing in PIWIL3 knockout females. In testes, PIWIL1 is the predominant PIWI in adult hamsters, and loss of PIWIL1 causes sterility with severe spermatogenesis disorders.\",\n      \"method\": \"CRISPR/Cas9 knockout, immunofluorescence subcellular localization, RNA-seq, fertility assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with defined reproductive phenotypes in both sexes, TE silencing analysis, and expression profiling; replicated across all four PIWI family members in a single rigorous study\",\n      \"pmids\": [\"37644029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In human testes, PIWIL1 is expressed in spermatocytes and spermatids and is associated with transposon silencing. Expression of PIWIL1 in oocytes of adult human and bovine ovaries was demonstrated, with PIWIL1 expressed in adult human and bovine oocytes (bovine oocytes exclusively expressed PIWIL1 among PIWI family members).\",\n      \"method\": \"Immunohistochemistry, Western blot, quantitative proteome analysis, small RNA sequencing\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct protein localization and expression by proteomics and IHC across multiple species, single study\",\n      \"pmids\": [\"25818294\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PIWIL1 overexpression in endometrial cancer cells maintained stem-like characteristics including enhanced migration, invasion, and sphere-forming activity, and induced an EMT-like phenotype with increased mesenchymal markers and suppression of E-cadherin, as well as upregulated CD44 and ALDH1 expression.\",\n      \"method\": \"Stable transfection/shRNA knockdown, MTT assay, colony formation, transwell invasion, xenograft, qRT-PCR, Western blot, immunofluorescence\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — multiple functional assays with gain- and loss-of-function, in vitro and in vivo, but pathway mechanism not directly elucidated; single lab\",\n      \"pmids\": [\"26506848\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Viral-mediated knockdown of Piwil1 in the dorsal hippocampus of adult mice leads to enhanced contextual fear memory without affecting generalized anxiety, implicating PIWIL1 in behavioral regulation in the adult mammalian brain through modulation of plasticity-related gene expression.\",\n      \"method\": \"Viral-mediated shRNA knockdown in vivo, contextual fear conditioning behavioral assay\",\n      \"journal\": \"Neurobiology of learning and memory\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single behavioral readout, no direct molecular mechanism identified\",\n      \"pmids\": [\"30965112\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In colorectal cancer cells, Hiwi (PIWIL1) overexpression promoted cell proliferation and increased global DNA methylation levels. Chemical inhibition of DNA methylation significantly restrained this proliferation-promoting effect, suggesting PIWIL1 promotes cancer cell proliferation via increasing global DNA methylation.\",\n      \"method\": \"Adenovirus-mediated overexpression, cell proliferation assay, global DNA methylation measurement, DNMT inhibitor treatment\",\n      \"journal\": \"Disease markers\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, indirect mechanistic link (pharmacological inhibition of downstream effector), no direct molecular mechanism identified\",\n      \"pmids\": [\"26355242\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PIWIL1 (HIWI) is a PIWI-clade Argonaute protein that associates with piRNAs to form piRNA-induced silencing complexes (piRISCs) that cleave target transposon transcripts via an endonuclease activity potentiated by the accessory factor GTSF1; unlike AGO proteins, PIWIL1 tolerates extensive piRNA:target mismatches to broadly silence transposons. PIWIL1 contains symmetrical dimethyl-arginine modifications installed by PRMT5, enabling methylation-dependent Tudor domain interactions, while TDRD2 recognizes PIWIL1 via a methylation-independent mechanism that is required for piRNA 3'-end trimming. In somatic cancer contexts, PIWIL1 acts via piRNA-independent mechanisms, notably interacting with the UPF1-mediated nonsense-mediated mRNA decay pathway in gastric cancer, regulating mRNA stability of tumor suppressors in glioblastoma, binding and stabilizing Stathmin1 (suppressing its ubiquitination and phosphorylation) to destabilize microtubules and promote cell migration, and inducing global DNA hypermethylation to silence CDKI genes and drive tumorigenesis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PIWIL1 (HIWI) is a PIWI-clade Argonaute that, in the germline, loads piRNAs to form piRNA-induced silencing complexes (piRISCs) that direct transposon silencing during spermatogenesis and oogenesis [#15, #16, #17]. As a piRNA-guided endoribonuclease, its weak intrinsic slicing activity is potentiated into efficient target cleavage by the accessory factor GTSF1, and this catalytic activity is essential for functional sperm production [#4]. Unlike AGO-clade Argonautes, PIWIL1 cleaves targets that are only partially base-paired to its piRNA guide, tolerating mismatches at any position and dispensing with seed pairing [#5]; cryo-EM of mammalian PIWI piRISCs attributes this mismatch tolerance to a wider nucleic-acid channel and a vertebrate-specific lysine that distorts the piRNA seed and relaxes the seed gate upon target engagement [#6]. PIWIL1 carries symmetrical dimethyl-arginine marks installed by PRMT5 that mediate methylation-dependent Tudor-domain interactions [#2], whereas TDRD2 recognizes an unmethylated arginine-rich PIWIL1 sequence in a methylation-independent manner required for piRNA 3'-end trimming [#3]. In somatic cancers PIWIL1 acts largely independently of piRNAs: in gastric cancer its oncogenic function persists when piRNA binding is abolished and operates through interaction with the UPF1-dependent nonsense-mediated mRNA decay machinery [#7]; in glioma stem cells it sustains self-renewal by regulating the mRNA stability of tumor suppressors BTG2, FBXW7, and CDKN1B [#10]; it binds and stabilizes Stathmin1 by blocking its RLIM-mediated ubiquitination and CaMKII-mediated phosphorylation, thereby destabilizing microtubules and promoting migration [#8]; and it drives tumorigenesis by inducing global DNA hypermethylation that silences cyclin-dependent kinase inhibitors [#9]. PIWIL1 expression confers stem-like and oncogenic phenotypes across multiple tumor types, including sarcoma, endometrial, and hepatocellular carcinoma, where it also reshapes tumor metabolism and the immune microenvironment [#9, #11, #18].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established the first cellular context for human PIWIL1 — germline-restricted expression and a growth-suppressive/pro-apoptotic activity when ectopically expressed — framing it as a germline developmental regulator.\",\n      \"evidence\": \"RT-PCR, immunohistochemistry, and overexpression with apoptosis assays in testis and KG1 leukemia cells\",\n      \"pmids\": [\"12037681\", \"11154219\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular mechanism for the apoptotic phenotype\", \"piRNA/effector activity not yet linked\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined a post-translational regulatory layer: PRMT5-installed symmetrical dimethyl-arginines on PIWI proteins create docking sites for Tudor-domain partners.\",\n      \"evidence\": \"Biochemical methyltransferase assays and co-immunoprecipitation synthesized in review\",\n      \"pmids\": [\"20360382\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific Tudor partners of human PIWIL1 not individually mapped here\", \"Functional consequence of each interaction unresolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed an exception to the methylation paradigm — TDRD2 recognizes unmethylated PIWIL1 — and linked this interaction to piRNA biogenesis via 3'-end trimming.\",\n      \"evidence\": \"Crystal structure, in vitro binding/mutagenesis, and in vitro trimming assay\",\n      \"pmids\": [\"29118143\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo requirement for trimming in mammals not tested here\", \"Trimming nuclease identity not addressed\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Resolved how PIWIL1 becomes catalytically competent — GTSF1 converts its weak intrinsic slicer activity into efficient cleavage — and tied this catalysis to fertility.\",\n      \"evidence\": \"In vitro cleavage reconstitution with GTSF1 plus mouse knockout fertility phenotypes\",\n      \"pmids\": [\"35772669\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of GTSF1 potentiation not defined here\", \"Somatic relevance of catalysis untested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Explained why PIWI silencing is broad — PIWIL1 cleaves partially paired targets without requiring seed pairing, distinguishing it mechanistically from AGO Argonautes.\",\n      \"evidence\": \"In vitro binding and cleavage with recombinant mouse MIWI and sponge PIWI, mutational pairing analysis\",\n      \"pmids\": [\"37344600\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Target repertoire in vivo not enumerated\", \"Off-target consequences of mismatch tolerance unexamined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Provided the structural basis for mismatch tolerance — a wider channel, prearranged extended seed, and a vertebrate-specific lysine that relaxes the seed gate on target binding.\",\n      \"evidence\": \"Cryo-EM of MILI/HILI piRISCs with functional mutagenesis and in vitro assays\",\n      \"pmids\": [\"38658622\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct structures of PIWIL1 itself not solved here\", \"Catalytic step structures not captured\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Connected human germline PIWIL1 to its presumed ancestral function — transposon (LINE-1) silencing — across testis and oocytes of multiple species.\",\n      \"evidence\": \"Immunolocalization, laser-microdissection RT-PCR, proteomics, and small RNA sequencing in human and bovine gonads\",\n      \"pmids\": [\"28676534\", \"25818294\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causality between PIWIL1 and LINE-1 silencing correlative in human tissue\", \"piRNA target sites not mapped\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Demonstrated an essential, non-redundant reproductive requirement for PIWIL1 in a mammalian model with full PIWI-family coverage, including partial compensation for PIWIL3.\",\n      \"evidence\": \"CRISPR knockout of all four PIWI genes in golden hamster with fertility, localization, and RNA-seq analysis\",\n      \"pmids\": [\"37644029\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human germline phenotype inferred, not directly tested\", \"Molecular targets driving sterility not fully defined\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Opened the somatic-oncogenic chapter, linking PIWIL1 to tumorigenesis through global DNA hypermethylation and CDKI silencing reversible with DNMT inhibitors.\",\n      \"evidence\": \"In vitro differentiation, transgenic mouse sarcoma model, inducible knockdown, and DNA methylation analysis\",\n      \"pmids\": [\"22438986\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct molecular link between PIWIL1 and DNMT machinery not established\", \"piRNA dependence not tested here\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified a piRNA-independent protein-stabilization mechanism — PIWIL1 binds Stathmin1, blocking its ubiquitination and phosphorylation to destabilize microtubules and drive migration.\",\n      \"evidence\": \"Co-IP, ubiquitination/phosphorylation assays, microtubule polymerization, and migration assays\",\n      \"pmids\": [\"26317901\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab without structural definition of the interaction\", \"Tissue generality of the mechanism unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Formally separated PIWIL1's somatic oncogenic activity from its piRNA-binding function, implicating the UPF1/NMD pathway in gastric cancer.\",\n      \"evidence\": \"PIWIL1 knockout, RNA deep sequencing, piRNA-binding mutant rescue, and Co-IP with NMD factors\",\n      \"pmids\": [\"32848063\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How PIWIL1 modulates NMD activity mechanistically unresolved\", \"mRNA targets stabilized/destabilized not fully cataloged\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Extended the somatic mRNA-regulatory model to glioma stem cells, where PIWIL1 controls stability of BTG2, FBXW7, and CDKN1B to sustain self-renewal.\",\n      \"evidence\": \"shRNA knockdown, RNA-seq, mRNA stability assays, and xenograft models\",\n      \"pmids\": [\"33406417\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct PIWIL1–mRNA binding not demonstrated for each target\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Broadened PIWIL1's tumor roles to metabolic reprogramming and immune evasion in hepatocellular carcinoma via C3-mediated MDSC recruitment.\",\n      \"evidence\": \"Overexpression/knockdown, metabolic flux analysis, MDSC co-culture, C3 neutralization, and p38 MAPK inhibition\",\n      \"pmids\": [\"33633112\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which PIWIL1 induces C3 secretion unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Documented a residual piRNA-loaded, perinuclear nuage-like PIWIL1 complex in somatic cancer cells engaging carcinogenesis-related target mRNAs.\",\n      \"evidence\": \"Immunofluorescence, RNA immunoprecipitation, and RNA sequencing in colorectal cancer cells\",\n      \"pmids\": [\"31694219\", \"33389678\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional contribution of these piRNA-mRNA complexes versus piRNA-independent activity unclear\", \"Cleavage versus binding not distinguished\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How PIWIL1 switches between germline piRNA-guided slicing and its diverse piRNA-independent somatic functions — and what determines target selection in each mode — remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying mechanism linking NMD modulation, mRNA stabilization, Stathmin1 binding, and DNA hypermethylation\", \"No structure of human PIWIL1 in either germline or somatic complexes\", \"Direct molecular bridge to DNA methylation machinery unidentified\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [4, 5, 6]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [3, 12, 14]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [4, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 12]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [12]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [4, 5, 7]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [4, 16, 17]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [7, 9, 10]}\n    ],\n    \"complexes\": [\"piRISC\"],\n    \"partners\": [\"GTSF1\", \"TDRD2\", \"PRMT5\", \"UPF1\", \"STMN1\", \"HENMT1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}