{"gene":"MPLKIP","run_date":"2026-06-10T02:59:51","timeline":{"discoveries":[{"year":2005,"finding":"C7orf11/TTDN1 (MPLKIP) localizes to the nucleus, as determined by comparative immunofluorescence analysis, and does not influence TFIIH directly.","method":"Immunofluorescence / comparative immunofluorescence analysis","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct immunofluorescence localization, single lab, consistent with disease phenotype; negative result regarding TFIIH also reported","pmids":["15645389"],"is_preprint":false},{"year":2007,"finding":"TTDN1 (MPLKIP) physically interacts with Plk1 (polo-like kinase 1); this interaction requires phosphorylation of Thr120 in a consensus Plk1-binding motif at TTDN1's C terminus, as site-directed mutagenesis of Thr120 abolishes the interaction.","method":"Yeast two-hybrid screen, site-directed mutagenesis, co-localization","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus mutagenesis, single lab, two orthogonal methods (Y2H + mutagenesis)","pmids":["17310276"],"is_preprint":false},{"year":2007,"finding":"TTDN1 (MPLKIP) is phosphorylated by Cdk1 during mitosis at multiple residues including Ser93 and Ser104; this phosphorylation is required for its interaction with Plk1.","method":"Site-directed mutagenesis, in-cell phosphorylation assays","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis plus functional interaction assay, single lab","pmids":["17310276"],"is_preprint":false},{"year":2007,"finding":"TTDN1 (MPLKIP) co-localizes with Plk1 at the centrosome in mitosis and at the midbody during cytokinesis; overexpression or siRNA knockdown of TTDN1 causes multi-polar spindles and multiple nuclei, indicating a role in regulating mitosis and cytokinesis.","method":"Immunofluorescence co-localization, siRNA knockdown, overexpression","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment with functional consequence (spindle defects), single lab, two methods (siRNA + OE)","pmids":["17310276"],"is_preprint":false},{"year":2007,"finding":"Mutations in C7orf11/TTDN1 (MPLKIP) do not affect the cellular response to UV light or the steady-state level of TFIIH, indicating that MPLKIP's disease mechanism is distinct from the TFIIH-dependent photosensitive TTD pathway.","method":"UV survival assay, western blot for TFIIH levels in patient cells","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional UV assay and protein-level assessment in patient-derived cells, two orthogonal methods, single lab; negative finding regarding TFIIH pathway","pmids":["16977596"],"is_preprint":false},{"year":2016,"finding":"A splice variant (c.339+1G>A) in MPLKIP causes intron retention, leading to protein truncation and loss of a phosphorylation site, functionally validating the importance of the phosphorylation site for full-length protein.","method":"Splicing assay, Sanger sequencing, exome sequencing","journal":"BMC medical genetics","confidence":"Low","confidence_rationale":"Tier 3 / Weak — functional splicing assay in single study, single lab, limited mechanistic depth","pmids":["26880286"],"is_preprint":false},{"year":2023,"finding":"MPLKIP directly binds to the RNA lariat debranching enzyme DBR1, as demonstrated by mass spectrometry-based interaction proteomics; MPLKIP-deficient primary fibroblasts have reduced steady-state DBR1 protein levels, indicating that MPLKIP stabilizes DBR1.","method":"Mass spectrometry-based interaction proteomics (AP-MS), western blot in MPLKIP-deficient fibroblasts","journal":"EMBO molecular medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — AP-MS interaction proteomics plus protein-level functional consequence in patient-derived cells, replicated in complementary biochemical study (PMID:37507019)","pmids":["37800682"],"is_preprint":false},{"year":2023,"finding":"MPLKIP interacts with core splicing factors; in MPLKIP-deficient cells, impaired splicing is observed in human skin equivalents, leading to an imbalanced proteome affecting keratinocyte differentiation and skin development.","method":"Mass spectrometry-based interaction proteomics, human skin equivalents (HSE) model, proteomics","journal":"EMBO molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — AP-MS interaction data plus functional differentiation model, single lab, two orthogonal methods","pmids":["37800682"],"is_preprint":false},{"year":2023,"finding":"MPLKIP (trichothiodystrophy nonphotosensitive 1) directly binds human Dbr1 and stimulates its catalytic efficiency 19-fold in vitro; this activation is mediated through Dbr1's intrinsically disordered C-terminal domain, which MPLKIP requires for activation, as Dbr1 from Entamoeba histolytica (lacking this domain) is unaffected.","method":"In vitro debranching assay with purified proteins, NMR (disordered domain characterization), sequence analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with purified proteins showing 19-fold catalytic activation, NMR structural characterization, mechanistic domain dissection across species, single lab but multiple orthogonal methods","pmids":["37507019"],"is_preprint":false}],"current_model":"MPLKIP (TTDN1/C7orf11) is a nuclear protein that (1) acts as a Plk1-interacting partner required for proper mitosis and cytokinesis—binding to Plk1 requires Cdk1-mediated phosphorylation at Thr120 in its C-terminal Plk1-binding motif—and (2) stabilizes the RNA lariat debranching enzyme DBR1 and directly activates its catalytic efficiency ~19-fold through DBR1's intrinsically disordered C-terminal domain, thereby promoting proper pre-mRNA splicing; loss of MPLKIP reduces DBR1 levels and impairs keratinocyte differentiation, explaining the trichothiodystrophy phenotype."},"narrative":{"mechanistic_narrative":"MPLKIP (TTDN1/C7orf11) is a nuclear protein with dual roles in mitotic progression and pre-mRNA splicing, and its loss causes non-photosensitive trichothiodystrophy through a mechanism distinct from the TFIIH-dependent photosensitive form [PMID:15645389, PMID:16977596, PMID:37507019]. In mitosis, MPLKIP physically interacts with the polo-like kinase Plk1 via a C-terminal consensus Plk1-binding motif; this interaction depends on prior Cdk1-mediated phosphorylation, including at Thr120 and at Ser93/Ser104 [PMID:17310276]. MPLKIP co-localizes with Plk1 at the centrosome during mitosis and at the midbody during cytokinesis, and its dysregulation by knockdown or overexpression produces multipolar spindles and multinucleation, establishing a role in mitotic and cytokinetic fidelity [PMID:17310276]. In a second role, MPLKIP directly binds and stabilizes the RNA lariat debranching enzyme DBR1, raising steady-state DBR1 levels in primary cells and stimulating its catalytic efficiency ~19-fold in vitro through engagement of DBR1's intrinsically disordered C-terminal domain [PMID:37800682, PMID:37507019]. Through its interaction with DBR1 and core splicing factors, MPLKIP supports proper pre-mRNA splicing, and its loss impairs splicing and keratinocyte differentiation in human skin equivalents, linking the molecular defect to the trichothiodystrophy phenotype [PMID:37800682, PMID:37507019].","teleology":[{"year":2005,"claim":"Established that MPLKIP is a nuclear protein and, contrary to the canonical photosensitive trichothiodystrophy paradigm, does not act directly on TFIIH, signaling a distinct disease mechanism.","evidence":"Comparative immunofluorescence localization in patient-relevant cells","pmids":["15645389"],"confidence":"Medium","gaps":["Did not define molecular function","Subnuclear distribution and binding partners unresolved"]},{"year":2007,"claim":"Defined a phosphorylation-dependent mitotic role by showing MPLKIP binds Plk1 through a C-terminal Plk1-binding motif requiring Cdk1 priming phosphorylation.","evidence":"Yeast two-hybrid screen, site-directed mutagenesis of Thr120/Ser93/Ser104, in-cell phosphorylation assays","pmids":["17310276"],"confidence":"Medium","gaps":["Whether MPLKIP is a Plk1 substrate or scaffold not resolved","Downstream mitotic targets of the complex unknown","Single lab, two-hybrid based interaction"]},{"year":2007,"claim":"Connected the Plk1 interaction to function by localizing MPLKIP to the centrosome and midbody and showing perturbation causes spindle and cytokinesis defects.","evidence":"Immunofluorescence co-localization, siRNA knockdown and overexpression","pmids":["17310276"],"confidence":"Medium","gaps":["Mechanism by which MPLKIP loss causes multipolarity unclear","Relationship between mitotic defects and trichothiodystrophy not established"]},{"year":2007,"claim":"Confirmed in patient cells that MPLKIP disease is independent of UV response and TFIIH stability, separating it mechanistically from photosensitive TTD.","evidence":"UV survival assay and TFIIH western blot in patient-derived cells","pmids":["16977596"],"confidence":"Medium","gaps":["Did not identify the causal molecular pathway","Negative result; positive function still undefined"]},{"year":2016,"claim":"Provided clinical-genetic support that a phosphorylation-site-disrupting splice variant is pathogenic, reinforcing the functional importance of MPLKIP phosphorylation sites.","evidence":"Splicing assay, Sanger and exome sequencing of patient variant","pmids":["26880286"],"confidence":"Low","gaps":["Single study with limited mechanistic depth","Does not directly demonstrate functional loss of the phosphorylation-dependent activity"]},{"year":2023,"claim":"Identified a splicing-related function by showing MPLKIP binds and stabilizes the debranching enzyme DBR1 and core splicing factors, with loss impairing splicing and keratinocyte differentiation.","evidence":"AP-MS interaction proteomics, western blot in MPLKIP-deficient fibroblasts, human skin equivalent differentiation model","pmids":["37800682"],"confidence":"High","gaps":["Mechanism of DBR1 stabilization not defined","Spectrum of mis-spliced transcripts driving the phenotype not fully mapped"]},{"year":2023,"claim":"Defined the biochemical mechanism of MPLKIP action on splicing by showing it directly activates DBR1 catalysis ~19-fold via DBR1's intrinsically disordered C-terminal domain.","evidence":"In vitro debranching assay with purified proteins, NMR of the disordered domain, cross-species domain dissection (Entamoeba histolytica Dbr1)","pmids":["37507019"],"confidence":"High","gaps":["Structure of the MPLKIP-DBR1 complex unknown","How activation integrates with the Plk1/mitotic role not addressed"]},{"year":null,"claim":"Whether the mitotic Plk1-dependent role and the splicing/DBR1 activation role represent independent functions or a unified mechanism remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No experiment links the centrosomal/cytokinesis function to DBR1 activation","Relative contribution of each role to trichothiodystrophy not quantified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[8]},{"term_id":"GO:0140313","term_label":"molecular sequestering activity","supporting_discovery_ids":[6]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[7,8]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[3]}],"complexes":[],"partners":["PLK1","DBR1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8TAP9","full_name":"M-phase-specific PLK1-interacting protein","aliases":["TTD non-photosensitive 1 protein"],"length_aa":179,"mass_kda":19.1,"function":"May play a role in maintenance of cell cycle integrity by regulating mitosis or cytokinesis","subcellular_location":"Nucleus; Cytoplasm; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome","url":"https://www.uniprot.org/uniprotkb/Q8TAP9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MPLKIP","classification":"Not Classified","n_dependent_lines":11,"n_total_lines":1208,"dependency_fraction":0.009105960264900662},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MPLKIP","total_profiled":1310},"omim":[{"mim_id":"616943","title":"TRICHOTHIODYSTROPHY 6, NONPHOTOSENSITIVE; TTD6","url":"https://www.omim.org/entry/616943"},{"mim_id":"609188","title":"M-PHASE-SPECIFIC PLK1-INTERACTING PROTEIN; MPLKIP","url":"https://www.omim.org/entry/609188"},{"mim_id":"601675","title":"TRICHOTHIODYSTROPHY 1, PHOTOSENSITIVE; TTD1","url":"https://www.omim.org/entry/601675"},{"mim_id":"234050","title":"TRICHOTHIODYSTROPHY 4, NONPHOTOSENSITIVE; TTD4","url":"https://www.omim.org/entry/234050"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Golgi apparatus","reliability":"Additional"},{"location":"Vesicles","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MPLKIP"},"hgnc":{"alias_symbol":["ORF20","TTDN1"],"prev_symbol":["C7orf11"]},"alphafold":{"accession":"Q8TAP9","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TAP9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TAP9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TAP9-F1-predicted_aligned_error_v6.png","plddt_mean":56.34},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MPLKIP","jax_strain_url":"https://www.jax.org/strain/search?query=MPLKIP"},"sequence":{"accession":"Q8TAP9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TAP9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TAP9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TAP9"}},"corpus_meta":[{"pmid":"15645389","id":"PMC_15645389","title":"Identification of C7orf11 (TTDN1) gene mutations and genetic heterogeneity in nonphotosensitive trichothiodystrophy.","date":"2005","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/15645389","citation_count":57,"is_preprint":false},{"pmid":"16513750","id":"PMC_16513750","title":"The integrase of the conjugative transposon Tn916 directs strand- and sequence-specific cleavage of the origin of conjugal transfer, oriT, by the endonuclease Orf20.","date":"2006","source":"Journal of bacteriology","url":"https://pubmed.ncbi.nlm.nih.gov/16513750","citation_count":39,"is_preprint":false},{"pmid":"25290684","id":"PMC_25290684","title":"Mutations in the TTDN1 gene are associated with a distinct trichothiodystrophy phenotype.","date":"2014","source":"The Journal of investigative dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/25290684","citation_count":31,"is_preprint":false},{"pmid":"16977596","id":"PMC_16977596","title":"Mutations in the C7orf11 (TTDN1) gene in six nonphotosensitive trichothiodystrophy patients: no obvious genotype-phenotype relationships.","date":"2007","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/16977596","citation_count":31,"is_preprint":false},{"pmid":"29499066","id":"PMC_29499066","title":"The interferon-stimulated gene product oligoadenylate synthetase-like protein enhances replication of Kaposi's sarcoma-associated herpesvirus (KSHV) and interacts with the KSHV ORF20 protein.","date":"2018","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/29499066","citation_count":26,"is_preprint":false},{"pmid":"17310276","id":"PMC_17310276","title":"TTDN1 is a Plk1-interacting protein involved in maintenance of cell cycle integrity.","date":"2007","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/17310276","citation_count":25,"is_preprint":false},{"pmid":"17412972","id":"PMC_17412972","title":"Murine gammaherpesvirus 68 ORF20 induces cell-cycle arrest in G2 by inhibiting the Cdc2-cyclin B complex.","date":"2007","source":"The Journal of general virology","url":"https://pubmed.ncbi.nlm.nih.gov/17412972","citation_count":23,"is_preprint":false},{"pmid":"37800682","id":"PMC_37800682","title":"Trichothiodystrophy-associated MPLKIP maintains DBR1 levels for proper lariat debranching and ectodermal differentiation.","date":"2023","source":"EMBO molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/37800682","citation_count":11,"is_preprint":false},{"pmid":"37507019","id":"PMC_37507019","title":"Activation of human RNA lariat debranching enzyme Dbr1 by binding protein TTDN1 occurs though an intrinsically disordered C-terminal domain.","date":"2023","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/37507019","citation_count":6,"is_preprint":false},{"pmid":"31383317","id":"PMC_31383317","title":"orf20 in prophage phiv142-3 contributes to the adhesion and colonization ability of avian pathogenic Escherichia coli strain DE142 by affecting the formation of flagella and I fimbriae.","date":"2019","source":"Veterinary microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/31383317","citation_count":6,"is_preprint":false},{"pmid":"26518168","id":"PMC_26518168","title":"A novel mutation in the C7orf11 gene causes nonphotosensitive trichothiodystrophy in a multiplex highly consanguineous kindred.","date":"2015","source":"European journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26518168","citation_count":5,"is_preprint":false},{"pmid":"30598092","id":"PMC_30598092","title":"A homozygous G insertion in MPLKIP leads to TTDN1 with the hypergonadotropic hypogonadism symptom.","date":"2018","source":"BMC medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30598092","citation_count":5,"is_preprint":false},{"pmid":"26880286","id":"PMC_26880286","title":"Mitral regurgitation as a phenotypic manifestation of nonphotosensitive trichothiodystrophy due to a splice variant in MPLKIP.","date":"2016","source":"BMC medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26880286","citation_count":5,"is_preprint":false},{"pmid":"34106579","id":"PMC_34106579","title":"The KSHV ORF20 Protein Interacts with the Viral Processivity Factor ORF59 and Promotes Viral Reactivation.","date":"2021","source":"Microbiology spectrum","url":"https://pubmed.ncbi.nlm.nih.gov/34106579","citation_count":4,"is_preprint":false},{"pmid":"25606444","id":"PMC_25606444","title":"Pollitt syndrome patients carry mutation in TTDN1.","date":"2014","source":"Meta gene","url":"https://pubmed.ncbi.nlm.nih.gov/25606444","citation_count":4,"is_preprint":false},{"pmid":"39339894","id":"PMC_39339894","title":"KSHV ORF20 Promotes Coordinated Lytic Reactivation for Increased Infectious Particle Production.","date":"2024","source":"Viruses","url":"https://pubmed.ncbi.nlm.nih.gov/39339894","citation_count":3,"is_preprint":false},{"pmid":"33729667","id":"PMC_33729667","title":"A novel MPLKIP-variant in three Finnish patients with non-photosensitive trichothiodystrophy type 4.","date":"2021","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/33729667","citation_count":1,"is_preprint":false},{"pmid":"21604555","id":"PMC_21604555","title":"[Function of the granaticin biosynthetic gene orf20 from Streptomyces vietnamensis].","date":"2011","source":"Wei sheng wu xue bao = Acta microbiologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/21604555","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11197,"output_tokens":2042,"usd":0.032111,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8992,"output_tokens":2502,"usd":0.053755,"stage2_stop_reason":"end_turn"},"total_usd":0.085866,"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\": 2005,\n      \"finding\": \"C7orf11/TTDN1 (MPLKIP) localizes to the nucleus, as determined by comparative immunofluorescence analysis, and does not influence TFIIH directly.\",\n      \"method\": \"Immunofluorescence / comparative immunofluorescence analysis\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct immunofluorescence localization, single lab, consistent with disease phenotype; negative result regarding TFIIH also reported\",\n      \"pmids\": [\"15645389\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"TTDN1 (MPLKIP) physically interacts with Plk1 (polo-like kinase 1); this interaction requires phosphorylation of Thr120 in a consensus Plk1-binding motif at TTDN1's C terminus, as site-directed mutagenesis of Thr120 abolishes the interaction.\",\n      \"method\": \"Yeast two-hybrid screen, site-directed mutagenesis, co-localization\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus mutagenesis, single lab, two orthogonal methods (Y2H + mutagenesis)\",\n      \"pmids\": [\"17310276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"TTDN1 (MPLKIP) is phosphorylated by Cdk1 during mitosis at multiple residues including Ser93 and Ser104; this phosphorylation is required for its interaction with Plk1.\",\n      \"method\": \"Site-directed mutagenesis, in-cell phosphorylation assays\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis plus functional interaction assay, single lab\",\n      \"pmids\": [\"17310276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"TTDN1 (MPLKIP) co-localizes with Plk1 at the centrosome in mitosis and at the midbody during cytokinesis; overexpression or siRNA knockdown of TTDN1 causes multi-polar spindles and multiple nuclei, indicating a role in regulating mitosis and cytokinesis.\",\n      \"method\": \"Immunofluorescence co-localization, siRNA knockdown, overexpression\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment with functional consequence (spindle defects), single lab, two methods (siRNA + OE)\",\n      \"pmids\": [\"17310276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Mutations in C7orf11/TTDN1 (MPLKIP) do not affect the cellular response to UV light or the steady-state level of TFIIH, indicating that MPLKIP's disease mechanism is distinct from the TFIIH-dependent photosensitive TTD pathway.\",\n      \"method\": \"UV survival assay, western blot for TFIIH levels in patient cells\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional UV assay and protein-level assessment in patient-derived cells, two orthogonal methods, single lab; negative finding regarding TFIIH pathway\",\n      \"pmids\": [\"16977596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A splice variant (c.339+1G>A) in MPLKIP causes intron retention, leading to protein truncation and loss of a phosphorylation site, functionally validating the importance of the phosphorylation site for full-length protein.\",\n      \"method\": \"Splicing assay, Sanger sequencing, exome sequencing\",\n      \"journal\": \"BMC medical genetics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — functional splicing assay in single study, single lab, limited mechanistic depth\",\n      \"pmids\": [\"26880286\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MPLKIP directly binds to the RNA lariat debranching enzyme DBR1, as demonstrated by mass spectrometry-based interaction proteomics; MPLKIP-deficient primary fibroblasts have reduced steady-state DBR1 protein levels, indicating that MPLKIP stabilizes DBR1.\",\n      \"method\": \"Mass spectrometry-based interaction proteomics (AP-MS), western blot in MPLKIP-deficient fibroblasts\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — AP-MS interaction proteomics plus protein-level functional consequence in patient-derived cells, replicated in complementary biochemical study (PMID:37507019)\",\n      \"pmids\": [\"37800682\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MPLKIP interacts with core splicing factors; in MPLKIP-deficient cells, impaired splicing is observed in human skin equivalents, leading to an imbalanced proteome affecting keratinocyte differentiation and skin development.\",\n      \"method\": \"Mass spectrometry-based interaction proteomics, human skin equivalents (HSE) model, proteomics\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — AP-MS interaction data plus functional differentiation model, single lab, two orthogonal methods\",\n      \"pmids\": [\"37800682\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MPLKIP (trichothiodystrophy nonphotosensitive 1) directly binds human Dbr1 and stimulates its catalytic efficiency 19-fold in vitro; this activation is mediated through Dbr1's intrinsically disordered C-terminal domain, which MPLKIP requires for activation, as Dbr1 from Entamoeba histolytica (lacking this domain) is unaffected.\",\n      \"method\": \"In vitro debranching assay with purified proteins, NMR (disordered domain characterization), sequence analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with purified proteins showing 19-fold catalytic activation, NMR structural characterization, mechanistic domain dissection across species, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"37507019\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MPLKIP (TTDN1/C7orf11) is a nuclear protein that (1) acts as a Plk1-interacting partner required for proper mitosis and cytokinesis—binding to Plk1 requires Cdk1-mediated phosphorylation at Thr120 in its C-terminal Plk1-binding motif—and (2) stabilizes the RNA lariat debranching enzyme DBR1 and directly activates its catalytic efficiency ~19-fold through DBR1's intrinsically disordered C-terminal domain, thereby promoting proper pre-mRNA splicing; loss of MPLKIP reduces DBR1 levels and impairs keratinocyte differentiation, explaining the trichothiodystrophy phenotype.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MPLKIP (TTDN1/C7orf11) is a nuclear protein with dual roles in mitotic progression and pre-mRNA splicing, and its loss causes non-photosensitive trichothiodystrophy through a mechanism distinct from the TFIIH-dependent photosensitive form [#0, #4, #8]. In mitosis, MPLKIP physically interacts with the polo-like kinase Plk1 via a C-terminal consensus Plk1-binding motif; this interaction depends on prior Cdk1-mediated phosphorylation, including at Thr120 and at Ser93/Ser104 [#1, #2]. MPLKIP co-localizes with Plk1 at the centrosome during mitosis and at the midbody during cytokinesis, and its dysregulation by knockdown or overexpression produces multipolar spindles and multinucleation, establishing a role in mitotic and cytokinetic fidelity [#3]. In a second role, MPLKIP directly binds and stabilizes the RNA lariat debranching enzyme DBR1, raising steady-state DBR1 levels in primary cells and stimulating its catalytic efficiency ~19-fold in vitro through engagement of DBR1's intrinsically disordered C-terminal domain [#6, #8]. Through its interaction with DBR1 and core splicing factors, MPLKIP supports proper pre-mRNA splicing, and its loss impairs splicing and keratinocyte differentiation in human skin equivalents, linking the molecular defect to the trichothiodystrophy phenotype [#7, #8].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Established that MPLKIP is a nuclear protein and, contrary to the canonical photosensitive trichothiodystrophy paradigm, does not act directly on TFIIH, signaling a distinct disease mechanism.\",\n      \"evidence\": \"Comparative immunofluorescence localization in patient-relevant cells\",\n      \"pmids\": [\"15645389\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not define molecular function\", \"Subnuclear distribution and binding partners unresolved\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined a phosphorylation-dependent mitotic role by showing MPLKIP binds Plk1 through a C-terminal Plk1-binding motif requiring Cdk1 priming phosphorylation.\",\n      \"evidence\": \"Yeast two-hybrid screen, site-directed mutagenesis of Thr120/Ser93/Ser104, in-cell phosphorylation assays\",\n      \"pmids\": [\"17310276\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether MPLKIP is a Plk1 substrate or scaffold not resolved\", \"Downstream mitotic targets of the complex unknown\", \"Single lab, two-hybrid based interaction\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Connected the Plk1 interaction to function by localizing MPLKIP to the centrosome and midbody and showing perturbation causes spindle and cytokinesis defects.\",\n      \"evidence\": \"Immunofluorescence co-localization, siRNA knockdown and overexpression\",\n      \"pmids\": [\"17310276\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which MPLKIP loss causes multipolarity unclear\", \"Relationship between mitotic defects and trichothiodystrophy not established\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Confirmed in patient cells that MPLKIP disease is independent of UV response and TFIIH stability, separating it mechanistically from photosensitive TTD.\",\n      \"evidence\": \"UV survival assay and TFIIH western blot in patient-derived cells\",\n      \"pmids\": [\"16977596\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not identify the causal molecular pathway\", \"Negative result; positive function still undefined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Provided clinical-genetic support that a phosphorylation-site-disrupting splice variant is pathogenic, reinforcing the functional importance of MPLKIP phosphorylation sites.\",\n      \"evidence\": \"Splicing assay, Sanger and exome sequencing of patient variant\",\n      \"pmids\": [\"26880286\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single study with limited mechanistic depth\", \"Does not directly demonstrate functional loss of the phosphorylation-dependent activity\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified a splicing-related function by showing MPLKIP binds and stabilizes the debranching enzyme DBR1 and core splicing factors, with loss impairing splicing and keratinocyte differentiation.\",\n      \"evidence\": \"AP-MS interaction proteomics, western blot in MPLKIP-deficient fibroblasts, human skin equivalent differentiation model\",\n      \"pmids\": [\"37800682\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of DBR1 stabilization not defined\", \"Spectrum of mis-spliced transcripts driving the phenotype not fully mapped\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined the biochemical mechanism of MPLKIP action on splicing by showing it directly activates DBR1 catalysis ~19-fold via DBR1's intrinsically disordered C-terminal domain.\",\n      \"evidence\": \"In vitro debranching assay with purified proteins, NMR of the disordered domain, cross-species domain dissection (Entamoeba histolytica Dbr1)\",\n      \"pmids\": [\"37507019\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of the MPLKIP-DBR1 complex unknown\", \"How activation integrates with the Plk1/mitotic role not addressed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether the mitotic Plk1-dependent role and the splicing/DBR1 activation role represent independent functions or a unified mechanism remains unresolved.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No experiment links the centrosomal/cytokinesis function to DBR1 activation\", \"Relative contribution of each role to trichothiodystrophy not quantified\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"GO:0140313\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [7, 8]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"PLK1\", \"DBR1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}