{"gene":"MED24","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":1999,"finding":"Mouse TRAP100 (MED24) is a component of the TRAP complex and does not directly interact with thyroid hormone receptor (TR) or vitamin D receptor (VDR) in vitro, but co-precipitates in vivo with TRAP220, which directly contacts TR and VDR in a ligand-dependent manner, indicating TRAP100 is targeted to nuclear receptors through TRAP220. Overexpression of mTRAP100 enhances ligand-dependent transcription by TR and VDR, and tethering mTRAP100 to the GAL4 DNA-binding domain activates transcription constitutively, revealing an intrinsic transactivation function.","method":"In vitro binding assays, co-immunoprecipitation, transient transfection luciferase reporter assays, GAL4 tethering assay","journal":"Molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP and functional reporter assays in single lab, multiple orthogonal methods","pmids":["10406464"],"is_preprint":false},{"year":2002,"finding":"Genetic ablation of TRAP100 (MED24) in mice is lethal at early developmental stages with severe malformations, indicating it is essential for development but not cell viability per se. The TRAP100-deficient Mediator complex also lacks TRAP95 and TRAP150β/SUR2 (suggesting these form a submodule together), contains reduced CDK8/SRB10, yet retains unaltered binding to RNA polymerase II and most activators (except E1A). TRAP100-deficient cells show attenuated transcriptional activation by a wide variety of activators, placing the TRAP100-containing submodule in a secondary amplifying role beyond activator binding and RNA Pol II recruitment.","method":"Genetic knockout in mice, biochemical fractionation, co-immunoprecipitation, luciferase reporter assays in TRAP100-deficient cells","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — mouse KO with defined molecular phenotype, biochemical characterization of residual complex, multiple orthogonal methods; replicated across multiple assays","pmids":["12093747"],"is_preprint":false},{"year":2006,"finding":"In zebrafish, loss-of-function of trap100/med24 (the lessen mutation encoding a truncated protein) does not affect initial neural crest specification or migration, but specifically reduces proliferation of ENS precursors in the intestine. Cell transplantation studies show trap100 acts cell-autonomously in pharyngeal mesendoderm to influence neural crest-derived cartilage development secondarily.","method":"Forward genetic screen, antisense morpholino knockdown, phospho-histone H3 immunocytochemistry, cell transplantation, neural crest marker analysis","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic mutant confirmed by morpholino phenocopy, cell transplantation epistasis, multiple cellular markers, replicated approaches in one study","pmids":["16396911"],"is_preprint":false},{"year":2006,"finding":"In zebrafish retinal development, loss of Trap100/Med24 specifically decreases rod photoreceptor cell number, while loss of the paralogous subunit Crsp34/Med27 has the opposite effect (increased rods, decreased amacrine cells), demonstrating that different Mediator subunits have divergent, non-redundant functions in vertebrate CNS differentiation.","method":"Zebrafish genetic mutant analysis, cell-type-specific markers, genetic comparison of multiple mediator subunit mutants","journal":"Genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — comparative genetic analysis in zebrafish with defined cellular phenotypes, single lab study","pmids":["16582438"],"is_preprint":false},{"year":2010,"finding":"In Drosophila, Med24 is required for larval salivary gland programmed cell death downstream of ecdysone signaling; Med24 mutants block caspase cleavage. Unexpectedly, expression of key death regulator genes (rpr, hid) is normal in Med24 mutant salivary glands, placing Med24's role post-transcriptionally or at a step downstream of these regulators in the ecdysone-triggered death cascade.","method":"Drosophila genetic mutants, caspase cleavage assays, gene expression analysis of death regulator genes","journal":"Developmental dynamics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with defined molecular readout (caspase cleavage) and pathway placement by epistasis; single lab, two orthogonal methods","pmids":["20063412"],"is_preprint":false},{"year":2012,"finding":"MED24 and MED1 functionally cooperate within the Mediator complex for pubertal mammary gland development and breast carcinoma cell growth. MED1/MED24 double heterozygous knockout mice show profound retardation in ductal branching during puberty (absent in single knockouts), impaired DNA synthesis in both luminal and basal cells, and attenuated expression of ER target genes (E2F1, cyclin D1). Luciferase reporter assays in double-mutant MEFs show selective impairment in estrogen receptor (ER) functions.","method":"Double heterozygous knockout mice, BrdU DNA synthesis assay, luciferase reporter assay in MEFs, qRT-PCR for ER target genes","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic epistasis (double KO), multiple orthogonal methods (histology, DNA synthesis, reporter assay, gene expression), functional ER pathway placement","pmids":["22331469"],"is_preprint":false},{"year":2019,"finding":"ERBB2 signaling regulates MED24 expression during lung tumor development; in mouse models with Pten and Smad4 deletion in pulmonary epithelium, Erbb2 loss suppresses the transcriptional dysregulation caused by tumor suppressor deletion and reduces MED24 levels, identifying MED24 as a downstream oncogenic target of ERBB2 in this context.","method":"Genetic mouse models (conditional KO), transcriptome analysis, overlap with human lung cancer gene signatures","journal":"Cells","confidence":"Low","confidence_rationale":"Tier 3 / Weak — transcriptome-based target identification in mouse model, single lab, indirect mechanistic link between ERBB2 and MED24","pmids":["31248101"],"is_preprint":false},{"year":2025,"finding":"Patient-derived iPSCs harboring compound heterozygous mutations in MED24 fail to undergo apicobasal elongation during neuroepithelial differentiation, phenocopying the neuroepithelial elongation defect previously implicated in mice, establishing MED24 as required for proper neuroepithelial cell shape regulation in human cells.","method":"Patient-specific iPSC-derived neuroepithelial morphogenesis model, live imaging of cell morphology, comparison to congenic controls","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — preprint, single patient line with compound heterozygous mutations, no rescue experiment, morphological readout only","pmids":["bio_10.1101_2025.05.16.654453"],"is_preprint":true}],"current_model":"MED24 (TRAP100) is a subunit of the Mediator/TRAP transcriptional coactivator complex that forms a submodule with TRAP95 and TRAP150β/SUR2; it does not directly contact nuclear receptors but is recruited to them via TRAP220/MED1, possesses an intrinsic transactivation domain, cooperates specifically with MED1 to mediate estrogen receptor-driven transcription in mammary gland development, is required for CDK8 retention in the complex and for broad transcriptional activation by diverse activators, and plays cell-type-specific roles in vertebrate development including ENS precursor proliferation, retinal rod photoreceptor differentiation, ecdysone-triggered programmed cell death (downstream of death-gene transcription), and neuroepithelial apicobasal elongation."},"narrative":{"mechanistic_narrative":"MED24 (TRAP100) is a subunit of the Mediator/TRAP transcriptional coactivator complex that amplifies activator-driven transcription rather than serving as the primary activator-binding or RNA polymerase II-recruiting module [PMID:10406464, PMID:12093747]. It does not directly contact nuclear receptors but is targeted to them through the ligand-dependent receptor-binding subunit TRAP220/MED1, and it carries an intrinsic transactivation function that enhances ligand-dependent transcription by thyroid hormone and vitamin D receptors [PMID:10406464]. Within the complex MED24 forms a submodule with TRAP95 and TRAP150β/SUR2 and is required for retention of CDK8/SRB10, while complex integrity with RNA Pol II and most activators is preserved in its absence; loss of MED24 broadly attenuates transcriptional activation by diverse activators, defining a secondary amplifying role [PMID:12093747]. MED24 cooperates specifically with MED1 to drive estrogen receptor-dependent transcription, controlling pubertal mammary ductal branching and ER target gene expression such as E2F1 and cyclin D1 [PMID:22331469]. Across vertebrate and invertebrate development MED24 has cell-type-specific functions, including enteric nervous system precursor proliferation and rod photoreceptor differentiation in zebrafish [PMID:16396911, PMID:16582438] and ecdysone-triggered programmed cell death downstream of death-gene transcription in Drosophila [PMID:20063412], and its genetic ablation is lethal with severe malformations [PMID:12093747].","teleology":[{"year":1999,"claim":"Established how MED24 is incorporated into nuclear receptor signaling, showing it is recruited indirectly via TRAP220/MED1 yet carries an autonomous transactivation capacity.","evidence":"In vitro binding, co-IP, GAL4 tethering and reporter assays for TR/VDR activation","pmids":["10406464"],"confidence":"Medium","gaps":["The structural basis of the MED24–TRAP220 interaction is undefined","Whether the intrinsic transactivation function operates within the intact complex in vivo is unresolved"]},{"year":2002,"claim":"Defined MED24's position within Mediator architecture and its functional role, placing its submodule downstream of activator binding and Pol II recruitment as a transcriptional amplifier essential for development.","evidence":"Mouse knockout, biochemical fractionation of residual complex, co-IP, reporter assays in deficient cells","pmids":["12093747"],"confidence":"High","gaps":["The mechanism by which the MED24/TRAP95/SUR2 submodule retains CDK8 is unknown","Which activator subsets depend most on this amplifying step is not delineated"]},{"year":2006,"claim":"Demonstrated that MED24 has discrete, non-redundant developmental functions, controlling ENS precursor proliferation and acting cell-autonomously in pharyngeal mesendoderm.","evidence":"Zebrafish forward-genetic mutant, morpholino phenocopy, pH3 staining, cell transplantation","pmids":["16396911"],"confidence":"High","gaps":["The transcriptional targets mediating ENS proliferation are not identified","How a general coactivator produces such tissue-restricted effects is unexplained"]},{"year":2006,"claim":"Showed that individual Mediator subunits have divergent, even opposing, functions in CNS cell-fate decisions, distinguishing MED24 from the paralogous MED27.","evidence":"Comparative zebrafish mutant analysis with cell-type-specific retinal markers","pmids":["16582438"],"confidence":"Medium","gaps":["The gene programs underlying rod versus amacrine fate differences are uncharacterized","Mechanism of subunit-specific selectivity is unknown"]},{"year":2010,"claim":"Placed MED24 in the ecdysone-triggered cell death cascade at a step downstream of death-gene transcription, an unexpected role for a transcriptional coactivator.","evidence":"Drosophila mutants, caspase cleavage assays, expression analysis of rpr/hid","pmids":["20063412"],"confidence":"Medium","gaps":["Whether the role is genuinely post-transcriptional or reflects effects on unmeasured target genes is unresolved","The molecular step controlled by MED24 in caspase activation is undefined"]},{"year":2012,"claim":"Identified specific functional cooperation between MED24 and MED1 in estrogen receptor signaling, linking the subunit to mammary morphogenesis and ER target gene control.","evidence":"MED1/MED24 double heterozygous knockout mice, BrdU assay, reporter assays in MEFs, qRT-PCR of ER targets","pmids":["22331469"],"confidence":"High","gaps":["The biochemical basis of MED24–MED1 cooperativity is not resolved","Whether this cooperation extends to receptors beyond ER is unknown"]},{"year":2019,"claim":"Linked MED24 expression to ERBB2 signaling in lung tumorigenesis, positioning it as a downstream transcriptional output of oncogenic signaling.","evidence":"Conditional mouse cancer models, transcriptome analysis, human signature overlap","pmids":["31248101"],"confidence":"Low","gaps":["The connection between ERBB2 and MED24 is correlative, not mechanistic","No direct demonstration that MED24 mediates the oncogenic phenotype"]},{"year":2025,"claim":"Connected human MED24 mutations to a neuroepithelial morphogenesis defect, extending its developmental roles to apicobasal cell-shape regulation in human cells.","evidence":"Patient-derived iPSC neuroepithelial model, live imaging (preprint)","pmids":["bio_10.1101_2025.05.16.654453"],"confidence":"Low","gaps":["Single patient line with compound heterozygous mutations and no rescue experiment","Transcriptional targets controlling apicobasal elongation are unidentified"]},{"year":null,"claim":"It remains unknown how a broadly required Mediator amplifier subunit achieves the cell-type-specific and post-transcriptional functions observed across tissues and species.","evidence":"No single study integrates the molecular complex role with tissue-specific developmental phenotypes","pmids":[],"confidence":"Low","gaps":["No structural model of the MED24 submodule within Mediator","Direct genomic targets in each developmental context are undefined","Mechanism linking MED24 to apicobasal morphology and caspase activation unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,1,5]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,1,5]}],"complexes":["Mediator/TRAP complex"],"partners":["MED1","MED27"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O75448","full_name":"Mediator of RNA polymerase II transcription subunit 24","aliases":["Activator-recruited cofactor 100 kDa component","ARC100","Cofactor required for Sp1 transcriptional activation subunit 4","CRSP complex subunit 4","Mediator complex subunit 24","Thyroid hormone receptor-associated protein 4","Thyroid hormone receptor-associated protein complex 100 kDa component","Trap100","hTRAP100","Vitamin D3 receptor-interacting protein complex 100 kDa component","DRIP100"],"length_aa":989,"mass_kda":110.3,"function":"Component of the Mediator complex, a coactivator involved in the regulated transcription of nearly all RNA polymerase II-dependent genes. Mediator functions as a bridge to convey information from gene-specific regulatory proteins to the basal RNA polymerase II transcription machinery. Mediator is recruited to promoters by direct interactions with regulatory proteins and serves as a scaffold for the assembly of a functional preinitiation complex with RNA polymerase II and the general transcription factors","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/O75448/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MED24","classification":"Not Classified","n_dependent_lines":546,"n_total_lines":1208,"dependency_fraction":0.4519867549668874},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000008838","cell_line_id":"CID000234","localizations":[{"compartment":"nuclear_punctae","grade":3},{"compartment":"nucleoplasm","grade":3}],"interactors":[{"gene":"MED10","stoichiometry":10.0},{"gene":"MED11","stoichiometry":10.0},{"gene":"MED14","stoichiometry":10.0},{"gene":"MED17","stoichiometry":10.0},{"gene":"MED19","stoichiometry":10.0},{"gene":"MED20","stoichiometry":10.0},{"gene":"MED21","stoichiometry":10.0},{"gene":"MED25","stoichiometry":10.0},{"gene":"MED27","stoichiometry":10.0},{"gene":"MED29","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/target/CID000234","total_profiled":1310},"omim":[{"mim_id":"607000","title":"MEDIATOR COMPLEX SUBUNIT 24; MED24","url":"https://www.omim.org/entry/607000"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MED24"},"hgnc":{"alias_symbol":["TRAP100","KIAA0130","DRIP100","CRSP100","MED5"],"prev_symbol":["THRAP4","CRSP4"]},"alphafold":{"accession":"O75448","domains":[{"cath_id":"-","chopping":"4-228","consensus_level":"medium","plddt":88.7356,"start":4,"end":228},{"cath_id":"-","chopping":"431-444_476-692","consensus_level":"medium","plddt":84.8203,"start":431,"end":692},{"cath_id":"-","chopping":"844-863_882-989","consensus_level":"medium","plddt":74.5162,"start":844,"end":989},{"cath_id":"1.20.870","chopping":"243-392","consensus_level":"high","plddt":92.01,"start":243,"end":392},{"cath_id":"1.25.40","chopping":"708-842","consensus_level":"medium","plddt":86.7618,"start":708,"end":842}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O75448","model_url":"https://alphafold.ebi.ac.uk/files/AF-O75448-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O75448-F1-predicted_aligned_error_v6.png","plddt_mean":84.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MED24","jax_strain_url":"https://www.jax.org/strain/search?query=MED24"},"sequence":{"accession":"O75448","fasta_url":"https://rest.uniprot.org/uniprotkb/O75448.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O75448/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O75448"}},"corpus_meta":[{"pmid":"12093747","id":"PMC_12093747","title":"The TRAP100 component of the TRAP/Mediator complex is essential in broad transcriptional events and development.","date":"2002","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/12093747","citation_count":99,"is_preprint":false},{"pmid":"29203634","id":"PMC_29203634","title":"Mediator Complex Subunits MED2, MED5, MED16, and MED23 Genetically Interact in the Regulation of Phenylpropanoid Biosynthesis.","date":"2017","source":"The Plant cell","url":"https://pubmed.ncbi.nlm.nih.gov/29203634","citation_count":50,"is_preprint":false},{"pmid":"16230344","id":"PMC_16230344","title":"The structural and functional role of Med5 in the yeast Mediator tail module.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16230344","citation_count":43,"is_preprint":false},{"pmid":"16396911","id":"PMC_16396911","title":"lessen encodes a zebrafish trap100 required for enteric nervous system development.","date":"2006","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/16396911","citation_count":40,"is_preprint":false},{"pmid":"22331469","id":"PMC_22331469","title":"Mediator subunits MED1 and MED24 cooperatively contribute to pubertal mammary gland development and growth of breast carcinoma cells.","date":"2012","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/22331469","citation_count":38,"is_preprint":false},{"pmid":"20063412","id":"PMC_20063412","title":"Med24 and Mdh2 are required for Drosophila larval salivary gland cell death.","date":"2010","source":"Developmental dynamics : an official publication of the American Association of Anatomists","url":"https://pubmed.ncbi.nlm.nih.gov/20063412","citation_count":31,"is_preprint":false},{"pmid":"10406464","id":"PMC_10406464","title":"Identification of mouse TRAP100: a transcriptional coregulatory factor for thyroid hormone and vitamin D receptors.","date":"1999","source":"Molecular endocrinology (Baltimore, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/10406464","citation_count":30,"is_preprint":false},{"pmid":"22693636","id":"PMC_22693636","title":"Med5(Nut1) and Med17(Srb4) are direct targets of mediator histone H4 tail interactions.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22693636","citation_count":25,"is_preprint":false},{"pmid":"16582438","id":"PMC_16582438","title":"Differential roles of transcriptional mediator complex subunits Crsp34/Med27, Crsp150/Med14 and Trap100/Med24 during zebrafish retinal development.","date":"2006","source":"Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/16582438","citation_count":17,"is_preprint":false},{"pmid":"23991176","id":"PMC_23991176","title":"Functional studies of the yeast med5, med15 and med16 mediator tail subunits.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23991176","citation_count":13,"is_preprint":false},{"pmid":"31248101","id":"PMC_31248101","title":"ERBB2 Regulates MED24 during Cancer Progression in Mice with Pten and Smad4 Deletion in the Pulmonary Epithelium.","date":"2019","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/31248101","citation_count":7,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.05.16.654453","title":"Patient-specific iPSC models of neural tube defects identify underlying deficiencies in neuroepithelial cell shape regulation and differentiation","date":"2025-05-20","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.16.654453","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7352,"output_tokens":2294,"usd":0.028233,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9393,"output_tokens":2722,"usd":0.057508,"stage2_stop_reason":"end_turn"},"total_usd":0.085741,"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\": 1999,\n      \"finding\": \"Mouse TRAP100 (MED24) is a component of the TRAP complex and does not directly interact with thyroid hormone receptor (TR) or vitamin D receptor (VDR) in vitro, but co-precipitates in vivo with TRAP220, which directly contacts TR and VDR in a ligand-dependent manner, indicating TRAP100 is targeted to nuclear receptors through TRAP220. Overexpression of mTRAP100 enhances ligand-dependent transcription by TR and VDR, and tethering mTRAP100 to the GAL4 DNA-binding domain activates transcription constitutively, revealing an intrinsic transactivation function.\",\n      \"method\": \"In vitro binding assays, co-immunoprecipitation, transient transfection luciferase reporter assays, GAL4 tethering assay\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP and functional reporter assays in single lab, multiple orthogonal methods\",\n      \"pmids\": [\"10406464\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Genetic ablation of TRAP100 (MED24) in mice is lethal at early developmental stages with severe malformations, indicating it is essential for development but not cell viability per se. The TRAP100-deficient Mediator complex also lacks TRAP95 and TRAP150β/SUR2 (suggesting these form a submodule together), contains reduced CDK8/SRB10, yet retains unaltered binding to RNA polymerase II and most activators (except E1A). TRAP100-deficient cells show attenuated transcriptional activation by a wide variety of activators, placing the TRAP100-containing submodule in a secondary amplifying role beyond activator binding and RNA Pol II recruitment.\",\n      \"method\": \"Genetic knockout in mice, biochemical fractionation, co-immunoprecipitation, luciferase reporter assays in TRAP100-deficient cells\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mouse KO with defined molecular phenotype, biochemical characterization of residual complex, multiple orthogonal methods; replicated across multiple assays\",\n      \"pmids\": [\"12093747\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"In zebrafish, loss-of-function of trap100/med24 (the lessen mutation encoding a truncated protein) does not affect initial neural crest specification or migration, but specifically reduces proliferation of ENS precursors in the intestine. Cell transplantation studies show trap100 acts cell-autonomously in pharyngeal mesendoderm to influence neural crest-derived cartilage development secondarily.\",\n      \"method\": \"Forward genetic screen, antisense morpholino knockdown, phospho-histone H3 immunocytochemistry, cell transplantation, neural crest marker analysis\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic mutant confirmed by morpholino phenocopy, cell transplantation epistasis, multiple cellular markers, replicated approaches in one study\",\n      \"pmids\": [\"16396911\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"In zebrafish retinal development, loss of Trap100/Med24 specifically decreases rod photoreceptor cell number, while loss of the paralogous subunit Crsp34/Med27 has the opposite effect (increased rods, decreased amacrine cells), demonstrating that different Mediator subunits have divergent, non-redundant functions in vertebrate CNS differentiation.\",\n      \"method\": \"Zebrafish genetic mutant analysis, cell-type-specific markers, genetic comparison of multiple mediator subunit mutants\",\n      \"journal\": \"Genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — comparative genetic analysis in zebrafish with defined cellular phenotypes, single lab study\",\n      \"pmids\": [\"16582438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"In Drosophila, Med24 is required for larval salivary gland programmed cell death downstream of ecdysone signaling; Med24 mutants block caspase cleavage. Unexpectedly, expression of key death regulator genes (rpr, hid) is normal in Med24 mutant salivary glands, placing Med24's role post-transcriptionally or at a step downstream of these regulators in the ecdysone-triggered death cascade.\",\n      \"method\": \"Drosophila genetic mutants, caspase cleavage assays, gene expression analysis of death regulator genes\",\n      \"journal\": \"Developmental dynamics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with defined molecular readout (caspase cleavage) and pathway placement by epistasis; single lab, two orthogonal methods\",\n      \"pmids\": [\"20063412\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"MED24 and MED1 functionally cooperate within the Mediator complex for pubertal mammary gland development and breast carcinoma cell growth. MED1/MED24 double heterozygous knockout mice show profound retardation in ductal branching during puberty (absent in single knockouts), impaired DNA synthesis in both luminal and basal cells, and attenuated expression of ER target genes (E2F1, cyclin D1). Luciferase reporter assays in double-mutant MEFs show selective impairment in estrogen receptor (ER) functions.\",\n      \"method\": \"Double heterozygous knockout mice, BrdU DNA synthesis assay, luciferase reporter assay in MEFs, qRT-PCR for ER target genes\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic epistasis (double KO), multiple orthogonal methods (histology, DNA synthesis, reporter assay, gene expression), functional ER pathway placement\",\n      \"pmids\": [\"22331469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ERBB2 signaling regulates MED24 expression during lung tumor development; in mouse models with Pten and Smad4 deletion in pulmonary epithelium, Erbb2 loss suppresses the transcriptional dysregulation caused by tumor suppressor deletion and reduces MED24 levels, identifying MED24 as a downstream oncogenic target of ERBB2 in this context.\",\n      \"method\": \"Genetic mouse models (conditional KO), transcriptome analysis, overlap with human lung cancer gene signatures\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — transcriptome-based target identification in mouse model, single lab, indirect mechanistic link between ERBB2 and MED24\",\n      \"pmids\": [\"31248101\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Patient-derived iPSCs harboring compound heterozygous mutations in MED24 fail to undergo apicobasal elongation during neuroepithelial differentiation, phenocopying the neuroepithelial elongation defect previously implicated in mice, establishing MED24 as required for proper neuroepithelial cell shape regulation in human cells.\",\n      \"method\": \"Patient-specific iPSC-derived neuroepithelial morphogenesis model, live imaging of cell morphology, comparison to congenic controls\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — preprint, single patient line with compound heterozygous mutations, no rescue experiment, morphological readout only\",\n      \"pmids\": [\"bio_10.1101_2025.05.16.654453\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"MED24 (TRAP100) is a subunit of the Mediator/TRAP transcriptional coactivator complex that forms a submodule with TRAP95 and TRAP150β/SUR2; it does not directly contact nuclear receptors but is recruited to them via TRAP220/MED1, possesses an intrinsic transactivation domain, cooperates specifically with MED1 to mediate estrogen receptor-driven transcription in mammary gland development, is required for CDK8 retention in the complex and for broad transcriptional activation by diverse activators, and plays cell-type-specific roles in vertebrate development including ENS precursor proliferation, retinal rod photoreceptor differentiation, ecdysone-triggered programmed cell death (downstream of death-gene transcription), and neuroepithelial apicobasal elongation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MED24 (TRAP100) is a subunit of the Mediator/TRAP transcriptional coactivator complex that amplifies activator-driven transcription rather than serving as the primary activator-binding or RNA polymerase II-recruiting module [#0, #1]. It does not directly contact nuclear receptors but is targeted to them through the ligand-dependent receptor-binding subunit TRAP220/MED1, and it carries an intrinsic transactivation function that enhances ligand-dependent transcription by thyroid hormone and vitamin D receptors [#0]. Within the complex MED24 forms a submodule with TRAP95 and TRAP150\\u03b2/SUR2 and is required for retention of CDK8/SRB10, while complex integrity with RNA Pol II and most activators is preserved in its absence; loss of MED24 broadly attenuates transcriptional activation by diverse activators, defining a secondary amplifying role [#1]. MED24 cooperates specifically with MED1 to drive estrogen receptor-dependent transcription, controlling pubertal mammary ductal branching and ER target gene expression such as E2F1 and cyclin D1 [#5]. Across vertebrate and invertebrate development MED24 has cell-type-specific functions, including enteric nervous system precursor proliferation and rod photoreceptor differentiation in zebrafish [#2, #3] and ecdysone-triggered programmed cell death downstream of death-gene transcription in Drosophila [#4], and its genetic ablation is lethal with severe malformations [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established how MED24 is incorporated into nuclear receptor signaling, showing it is recruited indirectly via TRAP220/MED1 yet carries an autonomous transactivation capacity.\",\n      \"evidence\": \"In vitro binding, co-IP, GAL4 tethering and reporter assays for TR/VDR activation\",\n      \"pmids\": [\"10406464\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The structural basis of the MED24\\u2013TRAP220 interaction is undefined\", \"Whether the intrinsic transactivation function operates within the intact complex in vivo is unresolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Defined MED24's position within Mediator architecture and its functional role, placing its submodule downstream of activator binding and Pol II recruitment as a transcriptional amplifier essential for development.\",\n      \"evidence\": \"Mouse knockout, biochemical fractionation of residual complex, co-IP, reporter assays in deficient cells\",\n      \"pmids\": [\"12093747\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The mechanism by which the MED24/TRAP95/SUR2 submodule retains CDK8 is unknown\", \"Which activator subsets depend most on this amplifying step is not delineated\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Demonstrated that MED24 has discrete, non-redundant developmental functions, controlling ENS precursor proliferation and acting cell-autonomously in pharyngeal mesendoderm.\",\n      \"evidence\": \"Zebrafish forward-genetic mutant, morpholino phenocopy, pH3 staining, cell transplantation\",\n      \"pmids\": [\"16396911\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The transcriptional targets mediating ENS proliferation are not identified\", \"How a general coactivator produces such tissue-restricted effects is unexplained\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showed that individual Mediator subunits have divergent, even opposing, functions in CNS cell-fate decisions, distinguishing MED24 from the paralogous MED27.\",\n      \"evidence\": \"Comparative zebrafish mutant analysis with cell-type-specific retinal markers\",\n      \"pmids\": [\"16582438\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The gene programs underlying rod versus amacrine fate differences are uncharacterized\", \"Mechanism of subunit-specific selectivity is unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Placed MED24 in the ecdysone-triggered cell death cascade at a step downstream of death-gene transcription, an unexpected role for a transcriptional coactivator.\",\n      \"evidence\": \"Drosophila mutants, caspase cleavage assays, expression analysis of rpr/hid\",\n      \"pmids\": [\"20063412\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the role is genuinely post-transcriptional or reflects effects on unmeasured target genes is unresolved\", \"The molecular step controlled by MED24 in caspase activation is undefined\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified specific functional cooperation between MED24 and MED1 in estrogen receptor signaling, linking the subunit to mammary morphogenesis and ER target gene control.\",\n      \"evidence\": \"MED1/MED24 double heterozygous knockout mice, BrdU assay, reporter assays in MEFs, qRT-PCR of ER targets\",\n      \"pmids\": [\"22331469\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The biochemical basis of MED24\\u2013MED1 cooperativity is not resolved\", \"Whether this cooperation extends to receptors beyond ER is unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Linked MED24 expression to ERBB2 signaling in lung tumorigenesis, positioning it as a downstream transcriptional output of oncogenic signaling.\",\n      \"evidence\": \"Conditional mouse cancer models, transcriptome analysis, human signature overlap\",\n      \"pmids\": [\"31248101\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"The connection between ERBB2 and MED24 is correlative, not mechanistic\", \"No direct demonstration that MED24 mediates the oncogenic phenotype\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected human MED24 mutations to a neuroepithelial morphogenesis defect, extending its developmental roles to apicobasal cell-shape regulation in human cells.\",\n      \"evidence\": \"Patient-derived iPSC neuroepithelial model, live imaging (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.05.16.654453\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single patient line with compound heterozygous mutations and no rescue experiment\", \"Transcriptional targets controlling apicobasal elongation are unidentified\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how a broadly required Mediator amplifier subunit achieves the cell-type-specific and post-transcriptional functions observed across tissues and species.\",\n      \"evidence\": \"No single study integrates the molecular complex role with tissue-specific developmental phenotypes\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of the MED24 submodule within Mediator\", \"Direct genomic targets in each developmental context are undefined\", \"Mechanism linking MED24 to apicobasal morphology and caspase activation unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 1, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 1, 5]}\n    ],\n    \"complexes\": [\"Mediator/TRAP complex\"],\n    \"partners\": [\"MED1\", \"MED27\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}