{"gene":"LIX1L","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2015,"finding":"LIX1L is a putative RNA-binding protein (RBP) containing a double-stranded RNA binding motif that interacts with proteins RIOK1, nucleolin (NCL), and PABPC4, as well as multiple miRNAs (including has-miRNA-520a-5p, -300, -216b, -326, -190a, -548b-3p, -7-5p, and -1296) in HEK-293 cells, as identified by MALDI-TOF/TOF mass spectrometry and RNA immunoprecipitation-sequencing.","method":"MALDI-TOF/TOF mass spectrometry, RNA immunoprecipitation-sequencing (RIP-seq)","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 — reciprocal IP with MS identification, single lab","pmids":["26310847"],"is_preprint":false},{"year":2015,"finding":"LIX1L is phosphorylated at Tyr136 by candidate kinases ROS1, HCK, ABL1, ABL2, JAK3, LCK, and TYRO3; reduction of pTyr136 via a homeodomain peptide (PY136) inhibits LIX1L-induced cell proliferation in vitro and in vivo, and induces apoptosis.","method":"Kinase candidate screening, homeodomain peptide inhibition assay, in vitro and in vivo proliferation assays","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 — functional phospho-site identified with peptide inhibitor rescue, single lab","pmids":["26310847"],"is_preprint":false},{"year":2021,"finding":"LIX1L functions as a post-transcriptional regulator that suppresses miR-191-3p expression; in cholestatic liver, LIX1L deficiency restores miR-191-3p, which targets and downregulates Lrh-1, thereby inhibiting Cyp7a1 and Cyp8b1 bile acid synthesis enzymes and alleviating cholestatic liver injury.","method":"Lix1l knockout mice, miRNA microarray, AAV-mediated hepatic delivery of miR-191-3p, BDL and Mdr2-/- models","journal":"Journal of hepatology","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with specific phenotype, miRNA profiling, in vivo rescue with AAV, multiple cholestasis models","pmids":["33746084"],"is_preprint":false},{"year":2021,"finding":"Bile acid-induced LIX1L upregulation is dependent on the transcription factor Egr-1, which acts as a transcriptional activator binding the Lix1l promoter, as shown by chromatin immunoprecipitation assays.","method":"Chromatin immunoprecipitation (ChIP) assay","journal":"Journal of hepatology","confidence":"Medium","confidence_rationale":"Tier 2 — direct ChIP evidence, single lab","pmids":["33746084"],"is_preprint":false},{"year":2021,"finding":"LIX1L promotes hepatocellular carcinoma progression by increasing miR-21-3p expression, which targets and suppresses fructose-1,6-bisphosphatase (FBP1), thereby promoting glucose consumption, lactate production, and cancer cell migration/invasion; miR-21-3p inhibitor abrogates these LIX1L-induced effects.","method":"LIX1L knockdown/overexpression in HCC cells and in vivo orthotopic model, miR-21-3p inhibitor rescue, FBP1 expression analysis","journal":"Acta pharmaceutica Sinica. B","confidence":"Medium","confidence_rationale":"Tier 2 — KD/OE with pathway rescue, in vivo model, single lab","pmids":["34221869"],"is_preprint":false},{"year":2022,"finding":"LIX1L physically interacts with nucleolin (NCL) in the nucleoli of EMT NSCLC cells, where it induces ribosomal RNA (rRNA) synthesis; NCL knockdown or inhibition of rRNA synthesis reverses LIX1L-overexpression-mediated EMT functions and proliferation, establishing a LIX1L-NCL-rRNA synthesis axis.","method":"Co-immunoprecipitation, nucleolar localization imaging, NCL knockdown, rRNA synthesis inhibition assays in NSCLC cells","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2 — co-IP with functional rescue by NCL KD and rRNA inhibition, single lab","pmids":["36478492"],"is_preprint":false},{"year":2022,"finding":"LIX1L interacts with DCHS1-based cell adhesions and the septin cytoskeleton through a DCHS1-LIX1L-SEPT9 axis; this axis promotes filamentous actin organization to direct cell-ECM alignment and valve tissue shape during mitral valve development.","method":"Biochemical co-immunoprecipitation, mouse and cell culture models, cytoskeletal organization assays","journal":"Journal of cardiovascular development and disease","confidence":"Medium","confidence_rationale":"Tier 2 — co-IP establishing DCHS1-LIX1L-SEPT9 complex with functional actin phenotype, single lab","pmids":["35200715"],"is_preprint":false},{"year":2024,"finding":"Metabolic stress promotes PARP1-mediated poly-ADP-ribosylation of LIX1L, increasing its stability and RNA-binding ability; LIX1L then binds AU-rich elements in the 3'UTR and CDS of CD36 mRNA, stabilizing it and promoting CD36 expression, which drives lipid accumulation, inflammation, and tumor-prone liver microenvironment in MASH.","method":"PARP1 inhibition, poly-ADP-ribosylation assays, Lix1l knockout mice, RNA-binding/mRNA stability assays, MASH mouse models","journal":"Pharmacological research","confidence":"High","confidence_rationale":"Tier 1-2 — PTM identified with writer (PARP1), direct mRNA binding demonstrated, KO phenotype confirmed in vivo, multiple orthogonal methods","pmids":["39725340"],"is_preprint":false}],"current_model":"LIX1L is a poly-ADP-ribosylated RNA-binding protein that stabilizes target mRNAs (e.g., CD36) via AU-rich element binding, suppresses miRNA expression (miR-191-3p, miR-21-3p) to regulate bile acid synthesis and glucose metabolism, interacts with nucleolin to drive rRNA synthesis in the nucleolus, is phosphorylated at Tyr136 by kinases including ROS1 to promote cell proliferation, and participates in a DCHS1-LIX1L-SEPT9 axis linking cell adhesion to actin-cytoskeleton organization during cardiac valve development."},"narrative":{"teleology":[{"year":2015,"claim":"Establishing LIX1L as a novel RNA-binding protein and signaling hub resolved the basic molecular identity of a previously uncharacterized gene, revealing its capacity to bind double-stranded RNA, interact with RNA-processing proteins (NCL, PABPC4, RIOK1) and multiple miRNAs, and serve as a tyrosine-phosphorylation substrate whose phosphorylation at Tyr136 promotes cell proliferation.","evidence":"MALDI-TOF/TOF mass spectrometry, RIP-seq, kinase candidate screening, and homeodomain peptide inhibition assays in HEK-293 cells and xenograft models","pmids":["26310847"],"confidence":"Medium","gaps":["No endogenous kinase validated as the physiological Tyr136 writer in a specific tissue context","Functional consequences of individual miRNA interactions not tested","Protein–protein interactions lack reciprocal validation in independent labs"]},{"year":2021,"claim":"Demonstrating that LIX1L suppresses miR-191-3p to sustain bile acid synthesis answered how the liver coordinates post-transcriptional RNA regulation with metabolic output, establishing the Egr-1→LIX1L⊣miR-191-3p→LRH-1→CYP7A1/CYP8B1 axis in cholestasis.","evidence":"Lix1l knockout mice, miRNA microarray, AAV-mediated hepatic miR-191-3p delivery, BDL and Mdr2−/− cholestasis models, and ChIP for Egr-1 at the Lix1l promoter","pmids":["33746084"],"confidence":"High","gaps":["Mechanism by which LIX1L suppresses miR-191-3p biogenesis or stability is unknown","Whether additional hepatic miRNAs are regulated by LIX1L beyond the array hits remains untested"]},{"year":2021,"claim":"Showing that LIX1L upregulates miR-21-3p to repress FBP1 and reprogram glucose metabolism revealed a second, opposite-direction miRNA regulatory mode through which LIX1L drives the Warburg effect in hepatocellular carcinoma.","evidence":"LIX1L knockdown/overexpression in HCC cell lines, orthotopic tumor model, miR-21-3p inhibitor rescue, metabolic flux measurements","pmids":["34221869"],"confidence":"Medium","gaps":["Direct binding of LIX1L to miR-21-3p precursor or processing machinery not demonstrated","Whether miR-191-3p and miR-21-3p regulation share a common mechanism is unknown","Single-lab observation without independent replication"]},{"year":2022,"claim":"Identifying the LIX1L–nucleolin interaction in the nucleolus as a driver of rRNA synthesis during EMT expanded LIX1L's functional repertoire from cytoplasmic RNA regulation to nucleolar ribosome biogenesis.","evidence":"Co-immunoprecipitation, nucleolar localization imaging, NCL knockdown and rRNA synthesis inhibition in NSCLC cells","pmids":["36478492"],"confidence":"Medium","gaps":["Whether LIX1L directly binds rDNA or rRNA precursors versus acting only through NCL is unresolved","No structural or domain-mapping data for the LIX1L–NCL interface","Single-lab co-IP without reciprocal pull-down from NCL side"]},{"year":2022,"claim":"Placing LIX1L in a DCHS1–LIX1L–SEPT9 complex that organizes filamentous actin during mitral valve development revealed a non-RNA function linking cell adhesion to cytoskeletal morphogenesis.","evidence":"Co-immunoprecipitation, mouse valve tissue analysis, cell culture cytoskeletal organization assays","pmids":["35200715"],"confidence":"Medium","gaps":["Direct binding surfaces between DCHS1, LIX1L, and SEPT9 are unmapped","Whether LIX1L's RNA-binding activity contributes to the valve phenotype is untested","Single-lab observation; phenotype in Lix1l conditional knockout valves not reported"]},{"year":2024,"claim":"Demonstrating that PARP1-mediated poly-ADP-ribosylation stabilizes LIX1L and enhances its binding to AU-rich elements in CD36 mRNA resolved the post-translational mechanism coupling metabolic stress to LIX1L-driven lipid uptake and MASH pathogenesis.","evidence":"PARP1 inhibition, PARylation assays, Lix1l knockout mice, RNA-binding and mRNA half-life assays, MASH diet models","pmids":["39725340"],"confidence":"High","gaps":["Specific PARylation sites on LIX1L are not mapped","Whether PARylation also modulates LIX1L's miRNA-regulatory activities is unknown","Genome-wide identification of direct LIX1L mRNA targets beyond CD36 has not been performed"]},{"year":null,"claim":"A unified model explaining how LIX1L simultaneously suppresses some miRNAs, promotes others, stabilizes specific mRNAs, and participates in cytoskeletal complexes—and whether these functions are coordinated through shared or distinct domains and post-translational modifications—remains to be established.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model or domain-function mapping exists for LIX1L","Genome-wide direct RNA targets (CLIP-based) have not been defined","Tissue-specific versus universal functions of LIX1L are uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[0,7]}],"localization":[{"term_id":"GO:0005730","term_label":"nucleolus","supporting_discovery_ids":[5]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[6]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[2,4,7]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0,5,7]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[4,7]}],"complexes":["DCHS1-LIX1L-SEPT9"],"partners":["NCL","DCHS1","SEPT9","PABPC4","RIOK1","PARP1"],"other_free_text":[]},"mechanistic_narrative":"LIX1L is an RNA-binding protein that functions as a post-transcriptional regulator of mRNA stability and miRNA expression, thereby controlling bile acid synthesis, glucose metabolism, lipid uptake, and ribosomal biogenesis. LIX1L binds AU-rich elements in target mRNAs such as CD36, stabilizing them to promote lipid accumulation and inflammation; this RNA-binding activity is enhanced by PARP1-mediated poly-ADP-ribosylation under metabolic stress [PMID:39725340]. LIX1L also modulates miRNA levels—suppressing miR-191-3p to sustain bile acid synthesis via the LRH-1/CYP7A1 axis in cholestatic liver [PMID:33746084] and promoting miR-21-3p to repress FBP1 and drive glycolytic reprogramming in hepatocellular carcinoma [PMID:34221869]. Beyond its RNA-regulatory roles, LIX1L interacts with nucleolin in the nucleolus to stimulate rRNA synthesis and epithelial–mesenchymal transition [PMID:36478492], and participates in a DCHS1–LIX1L–SEPT9 complex that organizes the actin cytoskeleton during cardiac valve morphogenesis [PMID:35200715]."},"prefetch_data":{"uniprot":{"accession":"Q8IVB5","full_name":"LIX1-like protein","aliases":[],"length_aa":337,"mass_kda":36.6,"function":"","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q8IVB5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LIX1L","classification":"Not Classified","n_dependent_lines":26,"n_total_lines":1208,"dependency_fraction":0.02152317880794702},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/LIX1L","total_profiled":1310},"omim":[{"mim_id":"621464","title":"LIMB- AND CNS-EXPRESSED GENE 1-LIKE; LIX1L","url":"https://www.omim.org/entry/621464"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/LIX1L"},"hgnc":{"alias_symbol":["MGC46719"],"prev_symbol":[]},"alphafold":{"accession":"Q8IVB5","domains":[{"cath_id":"3.30.160.20","chopping":"73-176","consensus_level":"high","plddt":88.5117,"start":73,"end":176}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IVB5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IVB5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IVB5-F1-predicted_aligned_error_v6.png","plddt_mean":78.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LIX1L","jax_strain_url":"https://www.jax.org/strain/search?query=LIX1L"},"sequence":{"accession":"Q8IVB5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8IVB5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8IVB5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IVB5"}},"corpus_meta":[{"pmid":"30553813","id":"PMC_30553813","title":"CellMinerCDB for Integrative Cross-Database Genomics and Pharmacogenomics Analyses of Cancer Cell Lines.","date":"2018","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/30553813","citation_count":116,"is_preprint":false},{"pmid":"33746084","id":"PMC_33746084","title":"Limb expression 1-like (LIX1L) protein promotes cholestatic liver injury by regulating bile acid metabolism.","date":"2021","source":"Journal of hepatology","url":"https://pubmed.ncbi.nlm.nih.gov/33746084","citation_count":52,"is_preprint":false},{"pmid":"25785048","id":"PMC_25785048","title":"Upregulated MiR-1269 in hepatocellular carcinoma and its clinical significance.","date":"2015","source":"International journal of clinical and experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/25785048","citation_count":33,"is_preprint":false},{"pmid":"34221869","id":"PMC_34221869","title":"LIX1-like protein promotes liver cancer progression via miR-21-3p-mediated inhibition of fructose-1,6-bisphosphatase.","date":"2021","source":"Acta pharmaceutica Sinica. B","url":"https://pubmed.ncbi.nlm.nih.gov/34221869","citation_count":23,"is_preprint":false},{"pmid":"31378885","id":"PMC_31378885","title":"LncRNA TATDN1 induces the progression of hepatocellular carcinoma via targeting miRNA-6089.","date":"2019","source":"European review for medical and pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31378885","citation_count":13,"is_preprint":false},{"pmid":"35200715","id":"PMC_35200715","title":"DCHS1, Lix1L, and the Septin Cytoskeleton: Molecular and Developmental Etiology of Mitral Valve Prolapse.","date":"2022","source":"Journal of cardiovascular development and disease","url":"https://pubmed.ncbi.nlm.nih.gov/35200715","citation_count":10,"is_preprint":false},{"pmid":"26310847","id":"PMC_26310847","title":"Novel roles for LIX1L in promoting cancer cell proliferation through ROS1-mediated LIX1L phosphorylation.","date":"2015","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26310847","citation_count":10,"is_preprint":false},{"pmid":"36478492","id":"PMC_36478492","title":"Limb expression 1-like protein promotes epithelial-mesenchymal transition and epidermal growth factor receptor-tyrosine kinase inhibitor resistance via nucleolin-mediated ribosomal RNA synthesis in non-small cell lung cancer.","date":"2022","source":"Cancer science","url":"https://pubmed.ncbi.nlm.nih.gov/36478492","citation_count":8,"is_preprint":false},{"pmid":"39725340","id":"PMC_39725340","title":"LIX1L aggravates MASH-HCC progression by reprogramming of hepatic metabolism and microenvironment via CD36.","date":"2024","source":"Pharmacological research","url":"https://pubmed.ncbi.nlm.nih.gov/39725340","citation_count":4,"is_preprint":false},{"pmid":"38911375","id":"PMC_38911375","title":"A-to-I edited miR-154-p13-5p inhibited cell proliferation and migration and induced apoptosis by targeting LIX1L in the bladder cancer.","date":"2024","source":"Journal of Cancer","url":"https://pubmed.ncbi.nlm.nih.gov/38911375","citation_count":4,"is_preprint":false},{"pmid":"35692142","id":"PMC_35692142","title":"Construction of a Competitive Endogenous RNA Network Related to Exosomes in Diabetic Retinopathy.","date":"2023","source":"Combinatorial chemistry & high throughput screening","url":"https://pubmed.ncbi.nlm.nih.gov/35692142","citation_count":4,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7300,"output_tokens":1993,"usd":0.025898},"stage2":{"model":"claude-opus-4-6","input_tokens":5265,"output_tokens":2249,"usd":0.123825},"total_usd":0.149723,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2015,\n      \"finding\": \"LIX1L is a putative RNA-binding protein (RBP) containing a double-stranded RNA binding motif that interacts with proteins RIOK1, nucleolin (NCL), and PABPC4, as well as multiple miRNAs (including has-miRNA-520a-5p, -300, -216b, -326, -190a, -548b-3p, -7-5p, and -1296) in HEK-293 cells, as identified by MALDI-TOF/TOF mass spectrometry and RNA immunoprecipitation-sequencing.\",\n      \"method\": \"MALDI-TOF/TOF mass spectrometry, RNA immunoprecipitation-sequencing (RIP-seq)\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal IP with MS identification, single lab\",\n      \"pmids\": [\"26310847\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"LIX1L is phosphorylated at Tyr136 by candidate kinases ROS1, HCK, ABL1, ABL2, JAK3, LCK, and TYRO3; reduction of pTyr136 via a homeodomain peptide (PY136) inhibits LIX1L-induced cell proliferation in vitro and in vivo, and induces apoptosis.\",\n      \"method\": \"Kinase candidate screening, homeodomain peptide inhibition assay, in vitro and in vivo proliferation assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional phospho-site identified with peptide inhibitor rescue, single lab\",\n      \"pmids\": [\"26310847\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LIX1L functions as a post-transcriptional regulator that suppresses miR-191-3p expression; in cholestatic liver, LIX1L deficiency restores miR-191-3p, which targets and downregulates Lrh-1, thereby inhibiting Cyp7a1 and Cyp8b1 bile acid synthesis enzymes and alleviating cholestatic liver injury.\",\n      \"method\": \"Lix1l knockout mice, miRNA microarray, AAV-mediated hepatic delivery of miR-191-3p, BDL and Mdr2-/- models\",\n      \"journal\": \"Journal of hepatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with specific phenotype, miRNA profiling, in vivo rescue with AAV, multiple cholestasis models\",\n      \"pmids\": [\"33746084\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Bile acid-induced LIX1L upregulation is dependent on the transcription factor Egr-1, which acts as a transcriptional activator binding the Lix1l promoter, as shown by chromatin immunoprecipitation assays.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) assay\",\n      \"journal\": \"Journal of hepatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct ChIP evidence, single lab\",\n      \"pmids\": [\"33746084\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LIX1L promotes hepatocellular carcinoma progression by increasing miR-21-3p expression, which targets and suppresses fructose-1,6-bisphosphatase (FBP1), thereby promoting glucose consumption, lactate production, and cancer cell migration/invasion; miR-21-3p inhibitor abrogates these LIX1L-induced effects.\",\n      \"method\": \"LIX1L knockdown/overexpression in HCC cells and in vivo orthotopic model, miR-21-3p inhibitor rescue, FBP1 expression analysis\",\n      \"journal\": \"Acta pharmaceutica Sinica. B\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KD/OE with pathway rescue, in vivo model, single lab\",\n      \"pmids\": [\"34221869\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LIX1L physically interacts with nucleolin (NCL) in the nucleoli of EMT NSCLC cells, where it induces ribosomal RNA (rRNA) synthesis; NCL knockdown or inhibition of rRNA synthesis reverses LIX1L-overexpression-mediated EMT functions and proliferation, establishing a LIX1L-NCL-rRNA synthesis axis.\",\n      \"method\": \"Co-immunoprecipitation, nucleolar localization imaging, NCL knockdown, rRNA synthesis inhibition assays in NSCLC cells\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — co-IP with functional rescue by NCL KD and rRNA inhibition, single lab\",\n      \"pmids\": [\"36478492\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LIX1L interacts with DCHS1-based cell adhesions and the septin cytoskeleton through a DCHS1-LIX1L-SEPT9 axis; this axis promotes filamentous actin organization to direct cell-ECM alignment and valve tissue shape during mitral valve development.\",\n      \"method\": \"Biochemical co-immunoprecipitation, mouse and cell culture models, cytoskeletal organization assays\",\n      \"journal\": \"Journal of cardiovascular development and disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — co-IP establishing DCHS1-LIX1L-SEPT9 complex with functional actin phenotype, single lab\",\n      \"pmids\": [\"35200715\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Metabolic stress promotes PARP1-mediated poly-ADP-ribosylation of LIX1L, increasing its stability and RNA-binding ability; LIX1L then binds AU-rich elements in the 3'UTR and CDS of CD36 mRNA, stabilizing it and promoting CD36 expression, which drives lipid accumulation, inflammation, and tumor-prone liver microenvironment in MASH.\",\n      \"method\": \"PARP1 inhibition, poly-ADP-ribosylation assays, Lix1l knockout mice, RNA-binding/mRNA stability assays, MASH mouse models\",\n      \"journal\": \"Pharmacological research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — PTM identified with writer (PARP1), direct mRNA binding demonstrated, KO phenotype confirmed in vivo, multiple orthogonal methods\",\n      \"pmids\": [\"39725340\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LIX1L is a poly-ADP-ribosylated RNA-binding protein that stabilizes target mRNAs (e.g., CD36) via AU-rich element binding, suppresses miRNA expression (miR-191-3p, miR-21-3p) to regulate bile acid synthesis and glucose metabolism, interacts with nucleolin to drive rRNA synthesis in the nucleolus, is phosphorylated at Tyr136 by kinases including ROS1 to promote cell proliferation, and participates in a DCHS1-LIX1L-SEPT9 axis linking cell adhesion to actin-cytoskeleton organization during cardiac valve development.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"LIX1L is an RNA-binding protein that functions as a post-transcriptional regulator of mRNA stability and miRNA expression, thereby controlling bile acid synthesis, glucose metabolism, lipid uptake, and ribosomal biogenesis. LIX1L binds AU-rich elements in target mRNAs such as CD36, stabilizing them to promote lipid accumulation and inflammation; this RNA-binding activity is enhanced by PARP1-mediated poly-ADP-ribosylation under metabolic stress [PMID:39725340]. LIX1L also modulates miRNA levels—suppressing miR-191-3p to sustain bile acid synthesis via the LRH-1/CYP7A1 axis in cholestatic liver [PMID:33746084] and promoting miR-21-3p to repress FBP1 and drive glycolytic reprogramming in hepatocellular carcinoma [PMID:34221869]. Beyond its RNA-regulatory roles, LIX1L interacts with nucleolin in the nucleolus to stimulate rRNA synthesis and epithelial–mesenchymal transition [PMID:36478492], and participates in a DCHS1–LIX1L–SEPT9 complex that organizes the actin cytoskeleton during cardiac valve morphogenesis [PMID:35200715].\",\n  \"teleology\": [\n    {\n      \"year\": 2015,\n      \"claim\": \"Establishing LIX1L as a novel RNA-binding protein and signaling hub resolved the basic molecular identity of a previously uncharacterized gene, revealing its capacity to bind double-stranded RNA, interact with RNA-processing proteins (NCL, PABPC4, RIOK1) and multiple miRNAs, and serve as a tyrosine-phosphorylation substrate whose phosphorylation at Tyr136 promotes cell proliferation.\",\n      \"evidence\": \"MALDI-TOF/TOF mass spectrometry, RIP-seq, kinase candidate screening, and homeodomain peptide inhibition assays in HEK-293 cells and xenograft models\",\n      \"pmids\": [\"26310847\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No endogenous kinase validated as the physiological Tyr136 writer in a specific tissue context\",\n        \"Functional consequences of individual miRNA interactions not tested\",\n        \"Protein–protein interactions lack reciprocal validation in independent labs\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrating that LIX1L suppresses miR-191-3p to sustain bile acid synthesis answered how the liver coordinates post-transcriptional RNA regulation with metabolic output, establishing the Egr-1→LIX1L⊣miR-191-3p→LRH-1→CYP7A1/CYP8B1 axis in cholestasis.\",\n      \"evidence\": \"Lix1l knockout mice, miRNA microarray, AAV-mediated hepatic miR-191-3p delivery, BDL and Mdr2−/− cholestasis models, and ChIP for Egr-1 at the Lix1l promoter\",\n      \"pmids\": [\"33746084\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which LIX1L suppresses miR-191-3p biogenesis or stability is unknown\",\n        \"Whether additional hepatic miRNAs are regulated by LIX1L beyond the array hits remains untested\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showing that LIX1L upregulates miR-21-3p to repress FBP1 and reprogram glucose metabolism revealed a second, opposite-direction miRNA regulatory mode through which LIX1L drives the Warburg effect in hepatocellular carcinoma.\",\n      \"evidence\": \"LIX1L knockdown/overexpression in HCC cell lines, orthotopic tumor model, miR-21-3p inhibitor rescue, metabolic flux measurements\",\n      \"pmids\": [\"34221869\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct binding of LIX1L to miR-21-3p precursor or processing machinery not demonstrated\",\n        \"Whether miR-191-3p and miR-21-3p regulation share a common mechanism is unknown\",\n        \"Single-lab observation without independent replication\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identifying the LIX1L–nucleolin interaction in the nucleolus as a driver of rRNA synthesis during EMT expanded LIX1L's functional repertoire from cytoplasmic RNA regulation to nucleolar ribosome biogenesis.\",\n      \"evidence\": \"Co-immunoprecipitation, nucleolar localization imaging, NCL knockdown and rRNA synthesis inhibition in NSCLC cells\",\n      \"pmids\": [\"36478492\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether LIX1L directly binds rDNA or rRNA precursors versus acting only through NCL is unresolved\",\n        \"No structural or domain-mapping data for the LIX1L–NCL interface\",\n        \"Single-lab co-IP without reciprocal pull-down from NCL side\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Placing LIX1L in a DCHS1–LIX1L–SEPT9 complex that organizes filamentous actin during mitral valve development revealed a non-RNA function linking cell adhesion to cytoskeletal morphogenesis.\",\n      \"evidence\": \"Co-immunoprecipitation, mouse valve tissue analysis, cell culture cytoskeletal organization assays\",\n      \"pmids\": [\"35200715\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct binding surfaces between DCHS1, LIX1L, and SEPT9 are unmapped\",\n        \"Whether LIX1L's RNA-binding activity contributes to the valve phenotype is untested\",\n        \"Single-lab observation; phenotype in Lix1l conditional knockout valves not reported\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrating that PARP1-mediated poly-ADP-ribosylation stabilizes LIX1L and enhances its binding to AU-rich elements in CD36 mRNA resolved the post-translational mechanism coupling metabolic stress to LIX1L-driven lipid uptake and MASH pathogenesis.\",\n      \"evidence\": \"PARP1 inhibition, PARylation assays, Lix1l knockout mice, RNA-binding and mRNA half-life assays, MASH diet models\",\n      \"pmids\": [\"39725340\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Specific PARylation sites on LIX1L are not mapped\",\n        \"Whether PARylation also modulates LIX1L's miRNA-regulatory activities is unknown\",\n        \"Genome-wide identification of direct LIX1L mRNA targets beyond CD36 has not been performed\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A unified model explaining how LIX1L simultaneously suppresses some miRNAs, promotes others, stabilizes specific mRNAs, and participates in cytoskeletal complexes—and whether these functions are coordinated through shared or distinct domains and post-translational modifications—remains to be established.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model or domain-function mapping exists for LIX1L\",\n        \"Genome-wide direct RNA targets (CLIP-based) have not been defined\",\n        \"Tissue-specific versus universal functions of LIX1L are uncharacterized\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005730\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [2, 4, 7]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 5, 7]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [4, 7]}\n    ],\n    \"complexes\": [\n      \"DCHS1-LIX1L-SEPT9\"\n    ],\n    \"partners\": [\n      \"NCL\",\n      \"DCHS1\",\n      \"SEPT9\",\n      \"PABPC4\",\n      \"RIOK1\",\n      \"PARP1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}