{"gene":"LUC7L","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2021,"finding":"LUC7L (along with LUC7L2 and LUC7L3) binds core splicing factors via protein interaction; all three paralogs bind similar core but distinct regulatory splicing factors, likely mediated through their divergent arginine-serine-rich (RS) domains. Knockdown of each factor reveals mostly unique sets of dysregulated alternative splicing events dependent on their largely non-overlapping RNA binding locations.","method":"Protein interaction studies (co-immunoprecipitation/pulldown), RNA binding studies (CLIP), knockdown with transcriptome analysis","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal protein interaction data plus RNA binding experiments and transcriptome analysis, single lab, multiple orthogonal methods","pmids":["33852859"],"is_preprint":false},{"year":2021,"finding":"LUC7L crosslinks to weak 5' splice sites and to the 5' end of U1 snRNA, establishing an evolutionarily conserved role in 5' splice site selection (equivalent to yeast Luc7p function).","method":"RNA binding/crosslinking studies (CLIP or similar UV crosslinking), transcriptome analysis","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct RNA crosslinking experiment, single lab, multiple methods","pmids":["33852859"],"is_preprint":false},{"year":2025,"finding":"LUC7L and LUC7L2 preferentially enhance splicing of 'right-handed' 5' splice sites with stronger consensus matching on the intron side of the near-invariant /GU dinucleotide, defining a distinct class of regulated 5'SS. This was confirmed by mutating splice sites and swapping domains between human LUC7 paralogs.","method":"Knockdown with transcriptome analysis, splice site mutagenesis, domain-swap experiments, analysis of leukemia samples with LUC7L2 copy number variation","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — splice site mutagenesis, domain swapping, transcriptome analysis in multiple systems (cell lines, leukemias), cross-kingdom validation in Arabidopsis","pmids":["39979239"],"is_preprint":false},{"year":2004,"finding":"Murine Luc7l protein localizes to the nucleus in a speckled distribution pattern via its C-terminal arginine-serine-rich (RS) domain. Forced expression of Luc7l inhibits myogenesis in vitro, and endogenous Luc7l expression is negatively regulated during skeletal muscle differentiation.","method":"Gene trap identification, subcellular localization by imaging, forced overexpression in myoblast cell lines (Sol8, C2C12) with myogenic differentiation assay","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — direct localization experiment with functional consequence, overexpression phenotype in two cell lines, single lab","pmids":["15474286"],"is_preprint":false},{"year":2001,"finding":"LUC7L encodes a putative RNA-binding protein with similarity to yeast Luc7p subunit of the U1 snRNP splicing complex. The gene is widely transcribed and lies on human chromosome 16p13.3, defining the centromeric boundary of the alpha-globin regulatory domain.","method":"Genomic mapping, sequence analysis, characterization of transcription pattern","journal":"Genomics","confidence":"Low","confidence_rationale":"Tier 4 / Weak — sequence-based inference of function, no direct functional experiment on the protein itself","pmids":["11170747"],"is_preprint":false},{"year":2024,"finding":"Humanization of the second zinc finger (ZnF2) domain of yeast Luc7 to mirror that of human LUC7L or LUC7L2 results in altered usage of nonconsensus 5' splice sites, demonstrating that ZnF2 plays a specific role in splice site selection. The corresponding ZnF domain of LUC7L3 could not support yeast viability, indicating functional divergence among human paralogs. Humanization of Luc7 suppresses mutation of ATPase Prp28, suggesting different ZnF domains have different requirements for U1 release.","method":"Domain humanization (ZnF domain swapping), reporter assays, transcriptome analysis, genetic interactions (synthetic lethality/suppression), yeast viability assays","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vivo mutagenesis/domain swapping with reporter assays, transcriptome analysis, and genetic epistasis; single lab but multiple orthogonal methods","pmids":["38719745"],"is_preprint":false},{"year":2024,"finding":"PRPF40A knockdown causes increased productive splicing of Luc7l by skipping of a small 'poison exon', indicating homeostatic cross-regulation between the physically coupled spliceosomal components PRPF40A and LUC7L.","method":"Knockdown (PRPF40A) with transcriptome analysis in mouse neuroblastoma cells","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single knockdown approach, preprint not yet peer-reviewed","pmids":["bio_10.1101_2024.09.26.615222"],"is_preprint":true}],"current_model":"LUC7L is a U1 snRNP-associated splicing factor that localizes to nuclear speckles via its C-terminal RS domain, preferentially enhances splicing of 'right-handed' 5' splice sites (with stronger consensus on the intron side of the /GU dinucleotide) through its second zinc finger domain, binds core and distinct regulatory splicing factors via its RS domain, and negatively regulates myogenic differentiation when overexpressed; its splicing activity is subject to homeostatic cross-regulation by its spliceosomal partner PRPF40A through a poison exon mechanism."},"narrative":{"mechanistic_narrative":"LUC7L is a U1 snRNP-associated splicing factor that functions in 5' splice site recognition and selection [PMID:33852859, PMID:39979239]. It crosslinks to weak 5' splice sites and to the 5' end of U1 snRNA, an activity that is evolutionarily conserved with the yeast Luc7p subunit of the U1 snRNP [PMID:33852859]. Together with its paralog LUC7L2, LUC7L preferentially enhances splicing of a distinct class of 'right-handed' 5' splice sites that have stronger consensus on the intron side of the near-invariant /GU dinucleotide, and this specificity is conferred by its second zinc finger (ZnF2) domain [PMID:39979239, PMID:38719745]. ZnF2 humanization studies in yeast establish that this domain dictates nonconsensus 5' splice site usage and influences the requirement for ATPase-driven U1 release, distinguishing LUC7L function from the divergent paralog LUC7L3 [PMID:38719745]. LUC7L binds core spliceosomal factors and a distinct set of regulatory splicing factors through its arginine-serine-rich (RS) domain, which also directs its localization to nuclear speckles, and knockdown produces a largely unique program of dysregulated alternative splicing events [PMID:33852859, PMID:15474286]. Beyond splicing, forced expression of LUC7L inhibits myogenic differentiation, and endogenous expression is downregulated during skeletal muscle differentiation [PMID:15474286].","teleology":[{"year":2001,"claim":"Established LUC7L as a candidate splicing factor by identifying it as a widely transcribed RNA-binding protein with sequence similarity to the yeast U1 snRNP subunit Luc7p, framing the hypothesis that it participates in splicing.","evidence":"Genomic mapping, sequence analysis, and transcription profiling of human chromosome 16p13.3","pmids":["11170747"],"confidence":"Low","gaps":["Function inferred from sequence only, with no direct experiment on the protein","No demonstration of U1 snRNP association or splicing activity"]},{"year":2004,"claim":"Showed that LUC7L is a nuclear speckle protein with a cellular phenotype, linking its RS domain to subnuclear targeting and its expression to control of myogenic differentiation.","evidence":"Gene trap identification, imaging of subcellular localization, and forced overexpression in Sol8/C2C12 myoblasts with differentiation assays","pmids":["15474286"],"confidence":"Medium","gaps":["Mechanism connecting splicing activity to myogenesis not defined","Overexpression phenotype not corroborated by loss-of-function"]},{"year":2021,"claim":"Defined LUC7L's biochemical role by showing it binds core and distinct regulatory splicing factors and crosslinks to weak 5' splice sites and U1 snRNA, establishing a conserved 5' splice site selection function and paralog-specific splicing programs.","evidence":"Co-immunoprecipitation/pulldown, CLIP RNA crosslinking, and knockdown with transcriptome analysis","pmids":["33852859"],"confidence":"Medium","gaps":["Determinants of 5' splice site preference at sequence level not resolved","Distinct regulatory partners not individually validated"]},{"year":2024,"claim":"Localized 5' splice site selection specificity to the ZnF2 domain and revealed functional divergence among human paralogs, including differential requirements for U1 release.","evidence":"ZnF domain humanization of yeast Luc7, reporter assays, transcriptome analysis, and genetic suppression of Prp28 ATPase mutations","pmids":["38719745"],"confidence":"High","gaps":["Structural basis of ZnF2 splice-site discrimination not determined","LUC7L3 functional role left unexplained beyond non-complementation"]},{"year":2025,"claim":"Defined a quantitative sequence rule for LUC7L target sites, showing it and LUC7L2 enhance 'right-handed' 5' splice sites with intron-side consensus, generalized across cell lines, leukemias, and plants.","evidence":"Knockdown plus transcriptome analysis, splice site mutagenesis, domain swaps, and analysis of LUC7L2 copy-number-variant leukemias with Arabidopsis validation","pmids":["39979239"],"confidence":"High","gaps":["Physiological consequences of the right-handed splicing program in normal tissues not detailed","Direct disease causation by LUC7L itself not established"]},{"year":2024,"claim":"Implicated LUC7L in homeostatic cross-regulation, showing its productive splicing is controlled by a poison exon responsive to its spliceosomal partner PRPF40A.","evidence":"PRPF40A knockdown with transcriptome analysis in mouse neuroblastoma cells (preprint)","pmids":["bio_10.1101_2024.09.26.615222"],"confidence":"Low","gaps":["Single knockdown approach, preprint not peer-reviewed","Physical coupling of LUC7L and PRPF40A not directly demonstrated here","Poison exon regulation not confirmed in human cells"]},{"year":null,"claim":"How LUC7L's 5' splice site selection activity mechanistically governs cellular processes such as myogenesis, and whether its dysregulation directly drives disease, remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of LUC7L bound to U1 snRNP or 5'SS","Link between splicing program and myogenic phenotype unestablished","No direct Mendelian or oncogenic causation demonstrated for LUC7L"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,2,5]}],"localization":[{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[3]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[1,2,5]}],"complexes":["U1 snRNP"],"partners":["PRPF40A","LUC7L2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NQ29","full_name":"Putative RNA-binding protein Luc7-like 1","aliases":["Putative SR protein LUC7B1","SR+89"],"length_aa":371,"mass_kda":43.7,"function":"May bind to RNA via its Arg/Ser-rich domain","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q9NQ29/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LUC7L","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":[{"gene":"TNPO3","stoichiometry":10.0},{"gene":"SNRPA","stoichiometry":0.2},{"gene":"SNRPC","stoichiometry":0.2},{"gene":"SNRPF","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/LUC7L","total_profiled":1310},"omim":[{"mim_id":"607782","title":"LUC7-LIKE; LUC7L","url":"https://www.omim.org/entry/607782"},{"mim_id":"141850","title":"HEMOGLOBIN--ALPHA LOCUS 2; HBA2","url":"https://www.omim.org/entry/141850"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Mitochondria","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/LUC7L"},"hgnc":{"alias_symbol":["LUC7B1","hLuc7B1","Luc7"],"prev_symbol":[]},"alphafold":{"accession":"Q9NQ29","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NQ29","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NQ29-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NQ29-F1-predicted_aligned_error_v6.png","plddt_mean":68.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LUC7L","jax_strain_url":"https://www.jax.org/strain/search?query=LUC7L"},"sequence":{"accession":"Q9NQ29","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NQ29.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NQ29/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NQ29"}},"corpus_meta":[{"pmid":"33852859","id":"PMC_33852859","title":"Functional analyses of human LUC7-like proteins involved in splicing regulation and myeloid neoplasms.","date":"2021","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/33852859","citation_count":47,"is_preprint":false},{"pmid":"30309899","id":"PMC_30309899","title":"The U1 snRNP Subunit LUC7 Modulates Plant Development and Stress Responses via Regulation of Alternative Splicing.","date":"2018","source":"The Plant cell","url":"https://pubmed.ncbi.nlm.nih.gov/30309899","citation_count":43,"is_preprint":false},{"pmid":"19014439","id":"PMC_19014439","title":"The FF domains of yeast U1 snRNP protein Prp40 mediate interactions with Luc7 and Snu71.","date":"2008","source":"BMC biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19014439","citation_count":33,"is_preprint":false},{"pmid":"11170747","id":"PMC_11170747","title":"Characterization of a widely expressed gene (LUC7-LIKE; LUC7L) defining the centromeric boundary of the human alpha-globin domain.","date":"2001","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/11170747","citation_count":26,"is_preprint":false},{"pmid":"27354704","id":"PMC_27354704","title":"Structure-function analysis and genetic interactions of the Luc7 subunit of the Saccharomyces cerevisiae U1 snRNP.","date":"2016","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/27354704","citation_count":18,"is_preprint":false},{"pmid":"15474286","id":"PMC_15474286","title":"Serine-arginine-rich nuclear protein Luc7l regulates myogenesis in mice.","date":"2004","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/15474286","citation_count":12,"is_preprint":false},{"pmid":"39979239","id":"PMC_39979239","title":"LUC7 proteins define two major classes of 5' splice sites in animals and plants.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/39979239","citation_count":10,"is_preprint":false},{"pmid":"19364672","id":"PMC_19364672","title":"Increase in dual specificity phosphatase 1, TGF-beta stimulated gene 22, domain family protein 3 and Luc7 homolog (S. cerevisiae)-like messenger RNA after mechanical asphyxiation in the mouse lung.","date":"2009","source":"Legal medicine (Tokyo, Japan)","url":"https://pubmed.ncbi.nlm.nih.gov/19364672","citation_count":7,"is_preprint":false},{"pmid":"38719745","id":"PMC_38719745","title":"Functional analysis of the zinc finger modules of the Saccharomyces cerevisiae splicing factor Luc7.","date":"2024","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/38719745","citation_count":2,"is_preprint":false},{"pmid":"38376578","id":"PMC_38376578","title":"Circ-Luc7l Absence Attenuates Diabetic Nephropathy Progression by Reducing Mesangial Cell Excessive Proliferation, Inflammation, and Extracellular Matrix Accumulation via Mediating the miR-205-5p/Tgfbr1 Pathway.","date":"2024","source":"Biochemical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38376578","citation_count":1,"is_preprint":false},{"pmid":"25949195","id":"PMC_25949195","title":"Fish Myogenic Regulatory Protein LUC7L: Characterization and Expression Analysis in Korean Rose Bitterling (Rhodeus uyekii).","date":"2014","source":"Development & reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/25949195","citation_count":1,"is_preprint":false},{"pmid":"40409693","id":"PMC_40409693","title":"LUC7L-201 is an important regulator of skeletal muscle growth and development in goats identified through integration of nanopore and Illumina sequencing.","date":"2025","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/40409693","citation_count":1,"is_preprint":false},{"pmid":"38352541","id":"PMC_38352541","title":"Functional Analysis of the Zinc Finger Modules of the S. cerevisiae Splicing Factor Luc7.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/38352541","citation_count":0,"is_preprint":false},{"pmid":"29950741","id":"PMC_29950741","title":"[Identificación de fármacos reguladores de la actividad del promotor Egr-1 en fibroblastos humanos transducidos con AdΔegr-1-Luc7].","date":"2018","source":"Cirugia y cirujanos","url":"https://pubmed.ncbi.nlm.nih.gov/29950741","citation_count":0,"is_preprint":false},{"pmid":"41814313","id":"PMC_41814313","title":"Novel LUC7L::NUTM1 fusion in PDGFRA-rearranged myeloproliferative neoplasm with eosinophilia: a case report.","date":"2026","source":"World journal of surgical oncology","url":"https://pubmed.ncbi.nlm.nih.gov/41814313","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.10.29.685309","title":"A topologically conserved unstructured region helps positioning the evolutionarily conserved Prp40 WW domains to promote non-canonical intron splicing","date":"2025-10-30","source":"bioRxiv","url":"https://doi.org/10.1101/2025.10.29.685309","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.06.23.660422","title":"Charting the single cell transcriptional landscape governing visual imprinting","date":"2025-06-26","source":"bioRxiv","url":"https://doi.org/10.1101/2025.06.23.660422","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.09.26.615222","title":"Conserved role for spliceosomal component PRPF40A in microexon splicing","date":"2024-09-26","source":"bioRxiv","url":"https://doi.org/10.1101/2024.09.26.615222","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11375,"output_tokens":1730,"usd":0.030038,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8588,"output_tokens":2415,"usd":0.051658,"stage2_stop_reason":"end_turn"},"total_usd":0.081696,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2021,\n      \"finding\": \"LUC7L (along with LUC7L2 and LUC7L3) binds core splicing factors via protein interaction; all three paralogs bind similar core but distinct regulatory splicing factors, likely mediated through their divergent arginine-serine-rich (RS) domains. Knockdown of each factor reveals mostly unique sets of dysregulated alternative splicing events dependent on their largely non-overlapping RNA binding locations.\",\n      \"method\": \"Protein interaction studies (co-immunoprecipitation/pulldown), RNA binding studies (CLIP), knockdown with transcriptome analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal protein interaction data plus RNA binding experiments and transcriptome analysis, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"33852859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LUC7L crosslinks to weak 5' splice sites and to the 5' end of U1 snRNA, establishing an evolutionarily conserved role in 5' splice site selection (equivalent to yeast Luc7p function).\",\n      \"method\": \"RNA binding/crosslinking studies (CLIP or similar UV crosslinking), transcriptome analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct RNA crosslinking experiment, single lab, multiple methods\",\n      \"pmids\": [\"33852859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"LUC7L and LUC7L2 preferentially enhance splicing of 'right-handed' 5' splice sites with stronger consensus matching on the intron side of the near-invariant /GU dinucleotide, defining a distinct class of regulated 5'SS. This was confirmed by mutating splice sites and swapping domains between human LUC7 paralogs.\",\n      \"method\": \"Knockdown with transcriptome analysis, splice site mutagenesis, domain-swap experiments, analysis of leukemia samples with LUC7L2 copy number variation\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — splice site mutagenesis, domain swapping, transcriptome analysis in multiple systems (cell lines, leukemias), cross-kingdom validation in Arabidopsis\",\n      \"pmids\": [\"39979239\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Murine Luc7l protein localizes to the nucleus in a speckled distribution pattern via its C-terminal arginine-serine-rich (RS) domain. Forced expression of Luc7l inhibits myogenesis in vitro, and endogenous Luc7l expression is negatively regulated during skeletal muscle differentiation.\",\n      \"method\": \"Gene trap identification, subcellular localization by imaging, forced overexpression in myoblast cell lines (Sol8, C2C12) with myogenic differentiation assay\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — direct localization experiment with functional consequence, overexpression phenotype in two cell lines, single lab\",\n      \"pmids\": [\"15474286\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"LUC7L encodes a putative RNA-binding protein with similarity to yeast Luc7p subunit of the U1 snRNP splicing complex. The gene is widely transcribed and lies on human chromosome 16p13.3, defining the centromeric boundary of the alpha-globin regulatory domain.\",\n      \"method\": \"Genomic mapping, sequence analysis, characterization of transcription pattern\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — sequence-based inference of function, no direct functional experiment on the protein itself\",\n      \"pmids\": [\"11170747\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Humanization of the second zinc finger (ZnF2) domain of yeast Luc7 to mirror that of human LUC7L or LUC7L2 results in altered usage of nonconsensus 5' splice sites, demonstrating that ZnF2 plays a specific role in splice site selection. The corresponding ZnF domain of LUC7L3 could not support yeast viability, indicating functional divergence among human paralogs. Humanization of Luc7 suppresses mutation of ATPase Prp28, suggesting different ZnF domains have different requirements for U1 release.\",\n      \"method\": \"Domain humanization (ZnF domain swapping), reporter assays, transcriptome analysis, genetic interactions (synthetic lethality/suppression), yeast viability assays\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vivo mutagenesis/domain swapping with reporter assays, transcriptome analysis, and genetic epistasis; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"38719745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PRPF40A knockdown causes increased productive splicing of Luc7l by skipping of a small 'poison exon', indicating homeostatic cross-regulation between the physically coupled spliceosomal components PRPF40A and LUC7L.\",\n      \"method\": \"Knockdown (PRPF40A) with transcriptome analysis in mouse neuroblastoma cells\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single knockdown approach, preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2024.09.26.615222\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"LUC7L is a U1 snRNP-associated splicing factor that localizes to nuclear speckles via its C-terminal RS domain, preferentially enhances splicing of 'right-handed' 5' splice sites (with stronger consensus on the intron side of the /GU dinucleotide) through its second zinc finger domain, binds core and distinct regulatory splicing factors via its RS domain, and negatively regulates myogenic differentiation when overexpressed; its splicing activity is subject to homeostatic cross-regulation by its spliceosomal partner PRPF40A through a poison exon mechanism.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"LUC7L is a U1 snRNP-associated splicing factor that functions in 5' splice site recognition and selection [#1, #2]. It crosslinks to weak 5' splice sites and to the 5' end of U1 snRNA, an activity that is evolutionarily conserved with the yeast Luc7p subunit of the U1 snRNP [#1]. Together with its paralog LUC7L2, LUC7L preferentially enhances splicing of a distinct class of 'right-handed' 5' splice sites that have stronger consensus on the intron side of the near-invariant /GU dinucleotide, and this specificity is conferred by its second zinc finger (ZnF2) domain [#2, #5]. ZnF2 humanization studies in yeast establish that this domain dictates nonconsensus 5' splice site usage and influences the requirement for ATPase-driven U1 release, distinguishing LUC7L function from the divergent paralog LUC7L3 [#5]. LUC7L binds core spliceosomal factors and a distinct set of regulatory splicing factors through its arginine-serine-rich (RS) domain, which also directs its localization to nuclear speckles, and knockdown produces a largely unique program of dysregulated alternative splicing events [#0, #3]. Beyond splicing, forced expression of LUC7L inhibits myogenic differentiation, and endogenous expression is downregulated during skeletal muscle differentiation [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Established LUC7L as a candidate splicing factor by identifying it as a widely transcribed RNA-binding protein with sequence similarity to the yeast U1 snRNP subunit Luc7p, framing the hypothesis that it participates in splicing.\",\n      \"evidence\": \"Genomic mapping, sequence analysis, and transcription profiling of human chromosome 16p13.3\",\n      \"pmids\": [\"11170747\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Function inferred from sequence only, with no direct experiment on the protein\", \"No demonstration of U1 snRNP association or splicing activity\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Showed that LUC7L is a nuclear speckle protein with a cellular phenotype, linking its RS domain to subnuclear targeting and its expression to control of myogenic differentiation.\",\n      \"evidence\": \"Gene trap identification, imaging of subcellular localization, and forced overexpression in Sol8/C2C12 myoblasts with differentiation assays\",\n      \"pmids\": [\"15474286\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting splicing activity to myogenesis not defined\", \"Overexpression phenotype not corroborated by loss-of-function\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined LUC7L's biochemical role by showing it binds core and distinct regulatory splicing factors and crosslinks to weak 5' splice sites and U1 snRNA, establishing a conserved 5' splice site selection function and paralog-specific splicing programs.\",\n      \"evidence\": \"Co-immunoprecipitation/pulldown, CLIP RNA crosslinking, and knockdown with transcriptome analysis\",\n      \"pmids\": [\"33852859\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Determinants of 5' splice site preference at sequence level not resolved\", \"Distinct regulatory partners not individually validated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Localized 5' splice site selection specificity to the ZnF2 domain and revealed functional divergence among human paralogs, including differential requirements for U1 release.\",\n      \"evidence\": \"ZnF domain humanization of yeast Luc7, reporter assays, transcriptome analysis, and genetic suppression of Prp28 ATPase mutations\",\n      \"pmids\": [\"38719745\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of ZnF2 splice-site discrimination not determined\", \"LUC7L3 functional role left unexplained beyond non-complementation\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined a quantitative sequence rule for LUC7L target sites, showing it and LUC7L2 enhance 'right-handed' 5' splice sites with intron-side consensus, generalized across cell lines, leukemias, and plants.\",\n      \"evidence\": \"Knockdown plus transcriptome analysis, splice site mutagenesis, domain swaps, and analysis of LUC7L2 copy-number-variant leukemias with Arabidopsis validation\",\n      \"pmids\": [\"39979239\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological consequences of the right-handed splicing program in normal tissues not detailed\", \"Direct disease causation by LUC7L itself not established\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Implicated LUC7L in homeostatic cross-regulation, showing its productive splicing is controlled by a poison exon responsive to its spliceosomal partner PRPF40A.\",\n      \"evidence\": \"PRPF40A knockdown with transcriptome analysis in mouse neuroblastoma cells (preprint)\",\n      \"pmids\": [\"bio_10.1101_2024.09.26.615222\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single knockdown approach, preprint not peer-reviewed\", \"Physical coupling of LUC7L and PRPF40A not directly demonstrated here\", \"Poison exon regulation not confirmed in human cells\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How LUC7L's 5' splice site selection activity mechanistically governs cellular processes such as myogenesis, and whether its dysregulation directly drives disease, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of LUC7L bound to U1 snRNP or 5'SS\", \"Link between splicing program and myogenic phenotype unestablished\", \"No direct Mendelian or oncogenic causation demonstrated for LUC7L\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 2, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [1, 2, 5]}\n    ],\n    \"complexes\": [\"U1 snRNP\"],\n    \"partners\": [\"PRPF40A\", \"LUC7L2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"faith_supported":6,"faith_total":6,"faith_pct":100.0}}