{"gene":"CTDNEP1","run_date":"2026-06-09T22:57:19","timeline":{"discoveries":[{"year":2024,"finding":"Crystal structure of the human CTDNEP1-NEP1R1 complex reveals that NEP1R1 acts as an activating regulatory subunit that binds CTDNEP1 at a site distant from the active site to allosterically stabilize and activate CTDNEP1 phosphatase activity; substrate recognition is facilitated by a conserved Arg residue in CTDNEP1 that binds and orients substrate peptide in the active site; knockdown of NEP1R1 generates identical ER expansion phenotypes to loss of CTDNEP1, establishing them as a conserved complex that restricts ER membrane expansion.","method":"X-ray crystallography of CTDNEP1-NEP1R1 complex bound to pseudosubstrate peptide, in vitro phosphatase activity assays, mammalian cell knockdown with ER morphology readout","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with functional validation by mutagenesis and in vitro phosphatase assay, corroborated by independent preprint (PMID:38045299)","pmids":["38776370"],"is_preprint":false},{"year":2023,"finding":"Crystal structure of the human CTDNEP1-NEP1R1 complex (preprint version confirming peer-reviewed findings): NEP1R1 allosterically activates CTDNEP1 by binding distant from the active site; conserved Arg in CTDNEP1 orients substrate in active site; CTDNEP1 and NEP1R1 co-knockdown generate identical ER expansion phenotypes.","method":"X-ray crystallography, in vitro phosphatase assay, cell knockdown with ER morphology readout","journal":"bioRxiv","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with mutagenesis and functional assay; corroborates peer-reviewed PMID:38776370","pmids":["38045299"],"is_preprint":true},{"year":2024,"finding":"CTDNEP1-NEP1R1, together with scaffold protein MAN1 at the inner nuclear membrane, forms a complex that dephosphorylates receptor-regulated SMADs (R-SMADs) in the nucleus to terminate TGF-β superfamily signaling; MAN1 binds independently to the CTDNEP1-NEP1R1 phosphatase and to R-SMADs to promote their inactivation; disruption of this complex causes nuclear accumulation of phosphorylated R-SMADs and aberrant signaling even without TGF-β ligand.","method":"Domain mapping, structural prediction, mutagenesis, co-immunoprecipitation, phosphoproteomics, cell-based TGF-β signaling assays with R-SMAD dephosphorylation readout","journal":"bioRxiv","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal methods (structural prediction + domain mapping + mutagenesis + functional assays), single lab preprint","pmids":["bio_10.1101_2024.09.23.614427"],"is_preprint":true},{"year":2011,"finding":"Human CTDNEP1/Dullard is a phosphoserine phosphatase that shows substrate specificity for the insulin-dependent phosphorylation site (Ser106) of lipin1, with a kcat/Km of 2.9×10^4 M−1 s−1, and does not require an adaptor protein for this activity.","method":"Steady-state kinetic analysis using phosphoserine-bearing nonapeptides corresponding to lipin1 phosphorylation sites","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic kinetic assay with defined substrates, single lab but quantitative biochemical characterization","pmids":["21413788"],"is_preprint":false},{"year":2006,"finding":"Xenopus Dullard (ortholog of CTDNEP1) promotes ubiquitin-mediated proteasomal degradation of BMP receptors; it preferentially complexes with BMPRII and partially colocalizes with caveolin-1-positive compartments, suggesting degradation via the lipid raft-caveolar pathway; it also associates with BMP type I receptors and represses BMP-dependent phosphorylation of type I receptors; phosphatase activity is required for BMPR degradation and neural induction.","method":"Co-immunoprecipitation, colocalization with caveolin-1, phosphatase-dead mutant analysis, Xenopus morpholino knockdown with neural marker gene readout","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, dominant-negative phosphatase mutant, and in vivo functional rescue in Xenopus; multiple orthogonal methods in one study","pmids":["17141153"],"is_preprint":false},{"year":2016,"finding":"Drosophila Dullard (ortholog of CTDNEP1) physically interacts with phosphorylated Mad (R-Smad) via co-immunoprecipitation and dephosphorylates both C-terminal and linker phosphorylations of Mad to terminate BMP signaling; phosphatase-domain mutation abolishes dephosphorylation but not binding; Dullard acts as an alternative to proteasomal degradation for terminating BMP signaling.","method":"Co-immunoprecipitation, hypomorphic allele and RNAi knockdown with pMad western blot readout, Dullard overexpression, phosphatase-domain point mutation","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus loss-of-function genetics with quantitative phospho-readout, phosphatase-dead mutant dissecting binding from activity, single lab","pmids":["27578171"],"is_preprint":false},{"year":2021,"finding":"CTDNEP1/Dullard, a nuclear envelope phosphatase, directly interacts with the actin regulator Eps8L2; this interaction regulates formation and thickness of dorsal actin cables required for TAN line engagement and nuclear movement during cell migration; loss of either protein impairs nuclear positioning and cell migration.","method":"Co-immunoprecipitation/direct interaction assay, siRNA knockdown with nuclear positioning and cell migration readouts, actin cable imaging","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct interaction demonstrated, functional loss-of-function with specific cellular phenotype; single lab, two orthogonal methods","pmids":["33567288"],"is_preprint":false},{"year":2023,"finding":"CTDNEP1 deficiency stabilizes and activates MYC by elevating MYC Ser62 phosphorylation, and triggers chromosomal instability; phosphoproteomics reveals CTDNEP1 post-translationally modulates activities of chromosome segregation and mitotic checkpoint regulators including TOP2A and CHEK1.","method":"Ctdnep1 mouse knockout tumor model, phosphoproteomics, MYC phosphorylation (pSer62) western blot, chromosomal instability assays, co-targeting MYC and CHEK1 in tumor models","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo mouse model plus phosphoproteomics plus mechanistic phosphorylation assays, replicated in human tumor context","pmids":["36765089"],"is_preprint":false},{"year":2013,"finding":"Mouse Dullard/Ctdnep1 deletion in metanephric mesenchyme leads to massive nephron apoptosis associated with upregulation of phospho-Smad1/5/8, consistent with cell-autonomous inhibition of BMP signaling; BMP receptor kinase inhibitor LDN-193189 partially rescues the nephron defects, placing Dullard upstream of BMP receptor activity in kidney maintenance.","method":"Conditional knockout mouse, phospho-Smad1/5/8 immunostaining, pharmacological rescue with BMP receptor inhibitor LDN-193189","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO mouse with defined molecular phenotype (pSmad1/5/8) and pharmacological epistasis rescue, two independent labs (referenced)","pmids":["23360989"],"is_preprint":false},{"year":2015,"finding":"Dullard/Ctdnep1 suppresses TGF-β signaling during endochondral ossification; Dullard deficiency upregulates phospho-Smad2/3 and total Smad2/3 protein levels without increasing Smad2/3 mRNA, suggesting Dullard affects Smad2/3 protein stability; skeletal defects in Dullard-deficient mice are rescued by TGF-β type I receptor kinase blocker LY-364947.","method":"Conditional knockout mouse (Prx1-Cre), micromass culture, phospho-Smad2/3 and total Smad2/3 western blot, pharmacological rescue with LY-364947 in vivo","journal":"Journal of bone and mineral research","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO mouse with molecular readout (pSmad2/3 protein stability) plus pharmacological epistasis rescue in vivo, multiple orthogonal methods","pmids":["25155999"],"is_preprint":false},{"year":2013,"finding":"Mouse Dullard/Ctdnep1 loss impairs primordial germ cell formation by reducing WNT/β-catenin signaling and Dishevelled 2 (Dvl2) protein levels; compound heterozygosity with Wnt3 has synergistic effects on PGC reduction, placing Dullard as a positive modulator of WNT signaling in germ cell specification.","method":"Conditional mouse knockout, compound heterozygote genetic epistasis with Wnt3, β-catenin reporter assay, Dvl2 western blot","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis and protein level assays, single lab; BMP effect was negative in this context","pmids":["23469192"],"is_preprint":false},{"year":2020,"finding":"Dullard, acting as a nuclear phosphatase, tunes BMP signaling amplitude during cardiac outflow tract development; it maintains neural crest cells in a mesenchymal state by attenuating Sema3c expression and promoting Twist1 expression; loss of Dullard leads to premature NCC condensation and tetralogy of Fallot-like defects, with elevated pSmad1/5/8.","method":"Conditional mouse knockout (NCC-specific), BMP signaling reporter, pSmad1/5/8 immunostaining, gene expression analysis of Sema3c and Twist1","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO mouse with defined molecular readouts (pSmad1/5/8, downstream transcriptional targets), multiple orthogonal methods","pmids":["32105214"],"is_preprint":false},{"year":2011,"finding":"Drosophila Dullard (ddd) genetically interacts with BMP signaling pathway components to regulate wing vein formation; manipulation of ddd expression alters p-Mad levels; Dullard overexpression mislocalizes nuclear import machinery components Importin-β and RanGAP and alters membrane lipid staining, suggesting Dullard regulates nuclear envelope/membrane lipid homeostasis to affect BMP signaling.","method":"Genetic interaction screen (double mutant wing vein phenotype), pMad western blot, Importin-β and RanGAP localization by immunofluorescence, membrane lipid staining","journal":"Development, growth & differentiation","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — genetic epistasis plus localization experiments, single lab, Drosophila ortholog","pmids":["21790556"],"is_preprint":false},{"year":2024,"finding":"Ctdnep1 negatively regulates RANKL-induced osteoclast differentiation; Ctdnep1 knockdown increases phosphorylation of RANKL signaling components and elevates Nfatc1 protein even without RANKL stimulation, and enhances calcium-resorbing activity.","method":"siRNA knockdown in RAW264.7 cells, TRAP staining for osteoclast numbers, osteoclast marker gene qPCR, western blot for pRANKL signaling components and Nfatc1, calcium resorption assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — siRNA KD with multiple phenotypic and molecular readouts, single lab, cell line model","pmids":["38749090"],"is_preprint":false},{"year":2018,"finding":"Dullard/Ctdnep1 suppresses BMP signaling in ovarian granulosa cells; conditional deletion leads to hemorrhagic ovarian cysts and upregulation of BMP-inducible inhibitory Smads (Smad6/Smad7); pharmacological rescue with BMP receptor inhibitor LDN-193189 confirmed the mechanism is through BMP signaling.","method":"Conditional knockout mouse (Col1a1-Cre and Rosa26-CreER), Smad6/7 gene expression, BMP receptor inhibitor rescue","journal":"Genes to cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — inducible KO with pharmacological rescue and molecular readout, single lab","pmids":["29521016"],"is_preprint":false}],"current_model":"CTDNEP1 (Dullard) is a non-canonical serine/threonine phosphatase that forms a conserved complex with its activating regulatory subunit NEP1R1 at the inner nuclear/ER membrane; NEP1R1 allosterically activates CTDNEP1 at a site distant from the active site, and together with the scaffold MAN1, the complex dephosphorylates nuclear R-SMADs to terminate TGF-β/BMP superfamily signaling; CTDNEP1 also dephosphorylates lipin1 to regulate phospholipid/ER membrane homeostasis, modulates MYC stability via Ser62 phosphorylation and mitotic fidelity, and interacts with Eps8L2 to organize dorsal actin cables for nuclear positioning during cell migration."},"narrative":{"mechanistic_narrative":"CTDNEP1 (Dullard) is a non-canonical serine/threonine phosphatase that operates at the inner nuclear and ER membrane to terminate TGF-β/BMP superfamily signaling and to regulate membrane lipid homeostasis [PMID:38776370, PMID:21413788, PMID:17141153]. Its catalytic activity depends on the regulatory subunit NEP1R1, which binds at a site distant from the active site to allosterically stabilize and activate the enzyme, while a conserved Arg residue in CTDNEP1 orients substrate peptides for dephosphorylation; co-depletion of CTDNEP1 or NEP1R1 produces identical ER expansion phenotypes, defining them as an obligate functional complex [PMID:38776370]. Together with the inner nuclear membrane scaffold MAN1, the CTDNEP1-NEP1R1 phosphatase dephosphorylates nuclear receptor-regulated SMADs, and disruption of this complex causes accumulation of phosphorylated R-SMADs and aberrant signaling [PMID:bio_10.1101_2024.09.23.614427]. This signal-terminating role is conserved and context-dependent: CTDNEP1 dephosphorylates Mad/R-SMADs and promotes BMP receptor turnover in flies and Xenopus [PMID:17141153, PMID:27578171], and across mouse tissues its loss elevates pSmad1/5/8 or pSmad2/3 to drive defects in kidney maintenance, endochondral ossification, cardiac outflow tract development, and ovarian function, each rescuable by BMP or TGF-β receptor kinase inhibition [PMID:23360989, PMID:25155999, PMID:32105214, PMID:29521016]. Independent of signaling termination, CTDNEP1 dephosphorylates lipin1 at its insulin-dependent Ser106 site without requiring an adaptor [PMID:21413788], stabilizes the genome by limiting MYC Ser62 phosphorylation and modulating mitotic regulators including TOP2A and CHEK1 [PMID:36765089], and interacts with the actin regulator Eps8L2 to organize dorsal actin cables for nuclear positioning during cell migration [PMID:33567288].","teleology":[{"year":2006,"claim":"Established that the CTDNEP1 ortholog Dullard restrains BMP signaling, linking its phosphatase activity to receptor turnover and a developmental output.","evidence":"Co-IP, phosphatase-dead mutant, and morpholino knockdown with neural marker readout in Xenopus","pmids":["17141153"],"confidence":"High","gaps":["Direct substrate of the phosphatase not defined","Mechanism coupling phosphatase activity to receptor ubiquitination unresolved"]},{"year":2011,"claim":"Defined CTDNEP1 as a quantitative phosphoserine phosphatase with defined substrate specificity, separating its lipid-regulatory function from signaling roles.","evidence":"Steady-state kinetics on phosphoserine nonapeptides corresponding to lipin1 sites","pmids":["21413788"],"confidence":"High","gaps":["Activity measured on peptides, not full-length lipin1","Cellular consequences of lipin1 dephosphorylation not addressed here"]},{"year":2011,"claim":"Connected Dullard's BMP-modulating role to nuclear envelope and membrane lipid homeostasis, hinting at a membrane-based mechanism for signaling control.","evidence":"Genetic interaction with BMP components, pMad western, Importin-β/RanGAP localization and lipid staining in Drosophila","pmids":["21790556"],"confidence":"Medium","gaps":["Causal link between lipid changes and BMP output not established","Ortholog data may not transfer directly to human CTDNEP1"]},{"year":2013,"claim":"Demonstrated cell-autonomous BMP restraint by Dullard in mammalian organogenesis using pharmacological epistasis.","evidence":"Conditional knockout mouse with pSmad1/5/8 staining and LDN-193189 rescue in kidney","pmids":["23360989"],"confidence":"High","gaps":["Whether Dullard acts directly on R-SMADs or upstream receptors not distinguished","Substrate identity in vivo unconfirmed"]},{"year":2013,"claim":"Showed Dullard can act as a positive modulator of a distinct pathway (WNT/β-catenin), revealing context-dependent signaling roles beyond BMP.","evidence":"Conditional KO, Wnt3 compound heterozygote epistasis, β-catenin reporter, Dvl2 western in germ cell specification","pmids":["23469192"],"confidence":"Medium","gaps":["Mechanism by which Dullard supports Dvl2 levels unknown","Direct substrate in WNT pathway not identified"]},{"year":2015,"claim":"Extended Dullard's signaling control to the TGF-β/Smad2/3 branch and implicated regulation of R-SMAD protein stability.","evidence":"Prx1-Cre conditional KO, pSmad2/3 and total Smad2/3 western, LY-364947 rescue in skeletal development","pmids":["25155999"],"confidence":"High","gaps":["Mechanism linking phosphatase to Smad2/3 protein stability unresolved","Direct dephosphorylation of Smad2/3 not shown biochemically"]},{"year":2016,"claim":"Provided direct biochemical evidence that Dullard dephosphorylates R-SMADs (Mad) at both C-terminal and linker sites, defining an enzymatic mode of signal termination distinct from degradation.","evidence":"Reciprocal Co-IP, phosphatase-dead mutant separating binding from activity, loss-of-function with pMad readout in Drosophila","pmids":["27578171"],"confidence":"High","gaps":["Human R-SMAD substrate not directly demonstrated here","Role of regulatory subunits in this context not examined"]},{"year":2018,"claim":"Confirmed BMP-suppressive role in additional tissue via inducible deletion and pharmacological rescue.","evidence":"Inducible/conditional KO mouse, Smad6/7 expression, LDN-193189 rescue in ovarian granulosa cells","pmids":["29521016"],"confidence":"Medium","gaps":["Direct molecular substrate not identified","Single-lab observation"]},{"year":2020,"claim":"Showed Dullard tunes BMP signaling amplitude to control cell-fate decisions, connecting phosphatase activity to downstream transcriptional programs.","evidence":"NCC-specific conditional KO, BMP reporter, pSmad1/5/8 staining, Sema3c/Twist1 expression in cardiac outflow tract","pmids":["32105214"],"confidence":"High","gaps":["Direct substrate in this context not biochemically defined","How signaling amplitude is quantitatively set unclear"]},{"year":2021,"claim":"Revealed a non-signaling role for CTDNEP1 in cytoskeletal organization and nuclear positioning through a direct partner.","evidence":"Direct interaction assay with Eps8L2, siRNA knockdown with nuclear positioning, migration, and actin cable imaging","pmids":["33567288"],"confidence":"Medium","gaps":["Whether phosphatase activity is required for the Eps8L2 function not established","Substrate in actin regulation unknown"]},{"year":2023,"claim":"Implicated CTDNEP1 in genome stability and oncogenesis by limiting MYC phosphorylation and modulating mitotic regulators.","evidence":"Ctdnep1 KO mouse tumor model, phosphoproteomics, pSer62-MYC western, chromosomal instability assays, co-targeting MYC/CHEK1","pmids":["36765089"],"confidence":"High","gaps":["Whether CTDNEP1 directly dephosphorylates MYC Ser62 not shown","Direct vs indirect modulation of TOP2A/CHEK1 unresolved"]},{"year":2024,"claim":"Resolved the structural and mechanistic basis of CTDNEP1 activation, defining NEP1R1 as an allosteric activating subunit and a conserved Arg as the substrate-orienting residue.","evidence":"X-ray crystallography of CTDNEP1-NEP1R1 with pseudosubstrate, in vitro phosphatase assays, mutagenesis, ER morphology readout","pmids":["38776370","38045299"],"confidence":"High","gaps":["Physiological substrate repertoire engaged by the activated complex not fully enumerated","Regulation of complex assembly in vivo unclear"]},{"year":2024,"claim":"Integrated the phosphatase complex with the scaffold MAN1 to provide a molecular mechanism for nuclear R-SMAD dephosphorylation and signal termination.","evidence":"Domain mapping, structural prediction, mutagenesis, Co-IP, phosphoproteomics, TGF-β signaling assays (preprint)","pmids":["bio_10.1101_2024.09.23.614427"],"confidence":"High","gaps":["Preprint; peer review pending","Quantitative contribution of MAN1 recruitment vs intrinsic activity not separated"]},{"year":2024,"claim":"Demonstrated CTDNEP1 negatively regulates osteoclast differentiation, broadening its tissue-level roles in signaling restraint.","evidence":"siRNA knockdown in RAW264.7 cells, TRAP staining, marker qPCR, pRANKL/Nfatc1 western, calcium resorption assay","pmids":["38749090"],"confidence":"Medium","gaps":["Direct substrate in RANKL pathway not identified","Single cell-line model"]},{"year":null,"claim":"It remains unresolved how a single phosphatase complex coordinates its distinct substrate sets — R-SMADs, lipin1, MYC, and mitotic regulators — and how substrate selection is controlled across membrane compartments and tissues.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model of substrate selection","Spatial regulation between nuclear envelope and ER pools unclear","Direct in vivo human substrates largely inferred rather than demonstrated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,3,4,5,7]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,3]}],"localization":[{"term_id":"GO:0005635","term_label":"nuclear envelope","supporting_discovery_ids":[6,11]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,4,5,8,9,11]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[8,9,10,11]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[7]}],"complexes":["CTDNEP1-NEP1R1 phosphatase complex","CTDNEP1-NEP1R1-MAN1 complex"],"partners":["NEP1R1","MAN1","EPS8L2","BMPRII","MAD","LIPIN1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O95476","full_name":"CTD nuclear envelope phosphatase 1","aliases":["Serine/threonine-protein phosphatase dullard"],"length_aa":244,"mass_kda":28.4,"function":"Serine/threonine protein phosphatase forming with CNEP1R1 an active phosphatase complex that dephosphorylates and may activate LPIN1 and LPIN2. LPIN1 and LPIN2 are phosphatidate phosphatases that catalyze the conversion of phosphatidic acid to diacylglycerol and control the metabolism of fatty acids at different levels. May indirectly modulate the lipid composition of nuclear and/or endoplasmic reticulum membranes and be required for proper nuclear membrane morphology and/or dynamics. May also indirectly regulate the production of lipid droplets and triacylglycerol. May antagonize BMP signaling","subcellular_location":"Endoplasmic reticulum membrane; Nucleus membrane","url":"https://www.uniprot.org/uniprotkb/O95476/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CTDNEP1","classification":"Not Classified","n_dependent_lines":536,"n_total_lines":1208,"dependency_fraction":0.44370860927152317},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"ARL6IP1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/CTDNEP1","total_profiled":1310},"omim":[{"mim_id":"616869","title":"C-TERMINAL DOMAIN NUCLEAR ENVELOPE PHOSPHATASE 1 REGULATORY SUBUNIT 1; CNEP1R1","url":"https://www.omim.org/entry/616869"},{"mim_id":"610684","title":"C-TERMINAL DOMAIN NUCLEAR ENVELOPE PHOSPHATASE 1; CTDNEP1","url":"https://www.omim.org/entry/610684"},{"mim_id":"605518","title":"LIPIN 1; LPIN1","url":"https://www.omim.org/entry/605518"},{"mim_id":"155255","title":"MEDULLOBLASTOMA; MDB","url":"https://www.omim.org/entry/155255"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Lipid droplets","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"skeletal muscle","ntpm":395.2}],"url":"https://www.proteinatlas.org/search/CTDNEP1"},"hgnc":{"alias_symbol":["HSA011916","NET56"],"prev_symbol":["DULLARD"]},"alphafold":{"accession":"O95476","domains":[{"cath_id":"3.40.50.1000","chopping":"59-244","consensus_level":"medium","plddt":92.6628,"start":59,"end":244},{"cath_id":"1.20.5","chopping":"1-39","consensus_level":"medium","plddt":81.8431,"start":1,"end":39}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O95476","model_url":"https://alphafold.ebi.ac.uk/files/AF-O95476-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O95476-F1-predicted_aligned_error_v6.png","plddt_mean":90.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CTDNEP1","jax_strain_url":"https://www.jax.org/strain/search?query=CTDNEP1"},"sequence":{"accession":"O95476","fasta_url":"https://rest.uniprot.org/uniprotkb/O95476.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O95476/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O95476"}},"corpus_meta":[{"pmid":"17141153","id":"PMC_17141153","title":"Dullard promotes degradation and dephosphorylation of BMP receptors and is required for neural induction.","date":"2006","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/17141153","citation_count":68,"is_preprint":false},{"pmid":"12083771","id":"PMC_12083771","title":"Molecular cloning and characterization of dullard: a novel gene required for neural development.","date":"2002","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/12083771","citation_count":39,"is_preprint":false},{"pmid":"36765089","id":"PMC_36765089","title":"Loss of phosphatase CTDNEP1 potentiates aggressive medulloblastoma by triggering MYC amplification and genomic instability.","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/36765089","citation_count":25,"is_preprint":false},{"pmid":"23360989","id":"PMC_23360989","title":"The phosphatase Dullard negatively regulates BMP signalling and is essential for nephron maintenance after birth.","date":"2013","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/23360989","citation_count":25,"is_preprint":false},{"pmid":"21413788","id":"PMC_21413788","title":"Homo sapiens dullard protein phosphatase shows a preference for the insulin-dependent phosphorylation site of lipin1.","date":"2011","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21413788","citation_count":24,"is_preprint":false},{"pmid":"23469192","id":"PMC_23469192","title":"Dullard/Ctdnep1 modulates WNT signalling activity for the formation of primordial germ cells in the mouse embryo.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23469192","citation_count":23,"is_preprint":false},{"pmid":"21790556","id":"PMC_21790556","title":"Negative modulation of bone morphogenetic protein signaling by Dullard during wing vein formation in Drosophila.","date":"2011","source":"Development, growth & differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/21790556","citation_count":19,"is_preprint":false},{"pmid":"25155999","id":"PMC_25155999","title":"Dullard/Ctdnep1 regulates endochondral ossification via suppression of TGF-β signaling.","date":"2015","source":"Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research","url":"https://pubmed.ncbi.nlm.nih.gov/25155999","citation_count":18,"is_preprint":false},{"pmid":"32105214","id":"PMC_32105214","title":"Dullard-mediated Smad1/5/8 inhibition controls mouse cardiac neural crest cells condensation and outflow tract septation.","date":"2020","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/32105214","citation_count":18,"is_preprint":false},{"pmid":"33567288","id":"PMC_33567288","title":"Ctdnep1 and Eps8L2 regulate dorsal actin cables for nuclear positioning during cell migration.","date":"2021","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/33567288","citation_count":17,"is_preprint":false},{"pmid":"28287811","id":"PMC_28287811","title":"Two Triacylglycerol Pathway Genes, CTDNEP1 and LPIN1, are Down-Regulated by hsa-miR-122-5p in Hepatocytes.","date":"2017","source":"Archives of Iranian medicine","url":"https://pubmed.ncbi.nlm.nih.gov/28287811","citation_count":17,"is_preprint":false},{"pmid":"27578171","id":"PMC_27578171","title":"Drosophila Dullard functions as a Mad phosphatase to terminate BMP signaling.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/27578171","citation_count":12,"is_preprint":false},{"pmid":"29521016","id":"PMC_29521016","title":"Dullard deficiency causes hemorrhage in the adult ovarian follicles.","date":"2018","source":"Genes to cells : devoted to molecular & cellular mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/29521016","citation_count":10,"is_preprint":false},{"pmid":"38776370","id":"PMC_38776370","title":"Structure and mechanism of the human CTDNEP1-NEP1R1 membrane protein phosphatase complex necessary to maintain ER membrane morphology.","date":"2024","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/38776370","citation_count":7,"is_preprint":false},{"pmid":"38749090","id":"PMC_38749090","title":"Ctdnep1 phosphatase is required for negative regulation of RANKL-induced osteoclast differentiation in RAW264.7 cells.","date":"2024","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/38749090","citation_count":4,"is_preprint":false},{"pmid":"38045299","id":"PMC_38045299","title":"Structure and mechanism of the human CTDNEP1-NEP1R1 membrane protein phosphatase complex necessary to maintain ER membrane morphology.","date":"2023","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/38045299","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.09.23.614427","title":"Suppression of TGF-β/SMAD signaling by an inner nuclear membrane phosphatase complex","date":"2024-09-23","source":"bioRxiv","url":"https://doi.org/10.1101/2024.09.23.614427","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9970,"output_tokens":4116,"usd":0.045825,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11982,"output_tokens":4389,"usd":0.084818,"stage2_stop_reason":"end_turn"},"total_usd":0.130643,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2024,\n      \"finding\": \"Crystal structure of the human CTDNEP1-NEP1R1 complex reveals that NEP1R1 acts as an activating regulatory subunit that binds CTDNEP1 at a site distant from the active site to allosterically stabilize and activate CTDNEP1 phosphatase activity; substrate recognition is facilitated by a conserved Arg residue in CTDNEP1 that binds and orients substrate peptide in the active site; knockdown of NEP1R1 generates identical ER expansion phenotypes to loss of CTDNEP1, establishing them as a conserved complex that restricts ER membrane expansion.\",\n      \"method\": \"X-ray crystallography of CTDNEP1-NEP1R1 complex bound to pseudosubstrate peptide, in vitro phosphatase activity assays, mammalian cell knockdown with ER morphology readout\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with functional validation by mutagenesis and in vitro phosphatase assay, corroborated by independent preprint (PMID:38045299)\",\n      \"pmids\": [\"38776370\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Crystal structure of the human CTDNEP1-NEP1R1 complex (preprint version confirming peer-reviewed findings): NEP1R1 allosterically activates CTDNEP1 by binding distant from the active site; conserved Arg in CTDNEP1 orients substrate in active site; CTDNEP1 and NEP1R1 co-knockdown generate identical ER expansion phenotypes.\",\n      \"method\": \"X-ray crystallography, in vitro phosphatase assay, cell knockdown with ER morphology readout\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with mutagenesis and functional assay; corroborates peer-reviewed PMID:38776370\",\n      \"pmids\": [\"38045299\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CTDNEP1-NEP1R1, together with scaffold protein MAN1 at the inner nuclear membrane, forms a complex that dephosphorylates receptor-regulated SMADs (R-SMADs) in the nucleus to terminate TGF-β superfamily signaling; MAN1 binds independently to the CTDNEP1-NEP1R1 phosphatase and to R-SMADs to promote their inactivation; disruption of this complex causes nuclear accumulation of phosphorylated R-SMADs and aberrant signaling even without TGF-β ligand.\",\n      \"method\": \"Domain mapping, structural prediction, mutagenesis, co-immunoprecipitation, phosphoproteomics, cell-based TGF-β signaling assays with R-SMAD dephosphorylation readout\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal methods (structural prediction + domain mapping + mutagenesis + functional assays), single lab preprint\",\n      \"pmids\": [\"bio_10.1101_2024.09.23.614427\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Human CTDNEP1/Dullard is a phosphoserine phosphatase that shows substrate specificity for the insulin-dependent phosphorylation site (Ser106) of lipin1, with a kcat/Km of 2.9×10^4 M−1 s−1, and does not require an adaptor protein for this activity.\",\n      \"method\": \"Steady-state kinetic analysis using phosphoserine-bearing nonapeptides corresponding to lipin1 phosphorylation sites\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic kinetic assay with defined substrates, single lab but quantitative biochemical characterization\",\n      \"pmids\": [\"21413788\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Xenopus Dullard (ortholog of CTDNEP1) promotes ubiquitin-mediated proteasomal degradation of BMP receptors; it preferentially complexes with BMPRII and partially colocalizes with caveolin-1-positive compartments, suggesting degradation via the lipid raft-caveolar pathway; it also associates with BMP type I receptors and represses BMP-dependent phosphorylation of type I receptors; phosphatase activity is required for BMPR degradation and neural induction.\",\n      \"method\": \"Co-immunoprecipitation, colocalization with caveolin-1, phosphatase-dead mutant analysis, Xenopus morpholino knockdown with neural marker gene readout\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, dominant-negative phosphatase mutant, and in vivo functional rescue in Xenopus; multiple orthogonal methods in one study\",\n      \"pmids\": [\"17141153\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Drosophila Dullard (ortholog of CTDNEP1) physically interacts with phosphorylated Mad (R-Smad) via co-immunoprecipitation and dephosphorylates both C-terminal and linker phosphorylations of Mad to terminate BMP signaling; phosphatase-domain mutation abolishes dephosphorylation but not binding; Dullard acts as an alternative to proteasomal degradation for terminating BMP signaling.\",\n      \"method\": \"Co-immunoprecipitation, hypomorphic allele and RNAi knockdown with pMad western blot readout, Dullard overexpression, phosphatase-domain point mutation\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus loss-of-function genetics with quantitative phospho-readout, phosphatase-dead mutant dissecting binding from activity, single lab\",\n      \"pmids\": [\"27578171\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CTDNEP1/Dullard, a nuclear envelope phosphatase, directly interacts with the actin regulator Eps8L2; this interaction regulates formation and thickness of dorsal actin cables required for TAN line engagement and nuclear movement during cell migration; loss of either protein impairs nuclear positioning and cell migration.\",\n      \"method\": \"Co-immunoprecipitation/direct interaction assay, siRNA knockdown with nuclear positioning and cell migration readouts, actin cable imaging\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct interaction demonstrated, functional loss-of-function with specific cellular phenotype; single lab, two orthogonal methods\",\n      \"pmids\": [\"33567288\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CTDNEP1 deficiency stabilizes and activates MYC by elevating MYC Ser62 phosphorylation, and triggers chromosomal instability; phosphoproteomics reveals CTDNEP1 post-translationally modulates activities of chromosome segregation and mitotic checkpoint regulators including TOP2A and CHEK1.\",\n      \"method\": \"Ctdnep1 mouse knockout tumor model, phosphoproteomics, MYC phosphorylation (pSer62) western blot, chromosomal instability assays, co-targeting MYC and CHEK1 in tumor models\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo mouse model plus phosphoproteomics plus mechanistic phosphorylation assays, replicated in human tumor context\",\n      \"pmids\": [\"36765089\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Mouse Dullard/Ctdnep1 deletion in metanephric mesenchyme leads to massive nephron apoptosis associated with upregulation of phospho-Smad1/5/8, consistent with cell-autonomous inhibition of BMP signaling; BMP receptor kinase inhibitor LDN-193189 partially rescues the nephron defects, placing Dullard upstream of BMP receptor activity in kidney maintenance.\",\n      \"method\": \"Conditional knockout mouse, phospho-Smad1/5/8 immunostaining, pharmacological rescue with BMP receptor inhibitor LDN-193189\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO mouse with defined molecular phenotype (pSmad1/5/8) and pharmacological epistasis rescue, two independent labs (referenced)\",\n      \"pmids\": [\"23360989\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Dullard/Ctdnep1 suppresses TGF-β signaling during endochondral ossification; Dullard deficiency upregulates phospho-Smad2/3 and total Smad2/3 protein levels without increasing Smad2/3 mRNA, suggesting Dullard affects Smad2/3 protein stability; skeletal defects in Dullard-deficient mice are rescued by TGF-β type I receptor kinase blocker LY-364947.\",\n      \"method\": \"Conditional knockout mouse (Prx1-Cre), micromass culture, phospho-Smad2/3 and total Smad2/3 western blot, pharmacological rescue with LY-364947 in vivo\",\n      \"journal\": \"Journal of bone and mineral research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO mouse with molecular readout (pSmad2/3 protein stability) plus pharmacological epistasis rescue in vivo, multiple orthogonal methods\",\n      \"pmids\": [\"25155999\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Mouse Dullard/Ctdnep1 loss impairs primordial germ cell formation by reducing WNT/β-catenin signaling and Dishevelled 2 (Dvl2) protein levels; compound heterozygosity with Wnt3 has synergistic effects on PGC reduction, placing Dullard as a positive modulator of WNT signaling in germ cell specification.\",\n      \"method\": \"Conditional mouse knockout, compound heterozygote genetic epistasis with Wnt3, β-catenin reporter assay, Dvl2 western blot\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis and protein level assays, single lab; BMP effect was negative in this context\",\n      \"pmids\": [\"23469192\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Dullard, acting as a nuclear phosphatase, tunes BMP signaling amplitude during cardiac outflow tract development; it maintains neural crest cells in a mesenchymal state by attenuating Sema3c expression and promoting Twist1 expression; loss of Dullard leads to premature NCC condensation and tetralogy of Fallot-like defects, with elevated pSmad1/5/8.\",\n      \"method\": \"Conditional mouse knockout (NCC-specific), BMP signaling reporter, pSmad1/5/8 immunostaining, gene expression analysis of Sema3c and Twist1\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO mouse with defined molecular readouts (pSmad1/5/8, downstream transcriptional targets), multiple orthogonal methods\",\n      \"pmids\": [\"32105214\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Drosophila Dullard (ddd) genetically interacts with BMP signaling pathway components to regulate wing vein formation; manipulation of ddd expression alters p-Mad levels; Dullard overexpression mislocalizes nuclear import machinery components Importin-β and RanGAP and alters membrane lipid staining, suggesting Dullard regulates nuclear envelope/membrane lipid homeostasis to affect BMP signaling.\",\n      \"method\": \"Genetic interaction screen (double mutant wing vein phenotype), pMad western blot, Importin-β and RanGAP localization by immunofluorescence, membrane lipid staining\",\n      \"journal\": \"Development, growth & differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — genetic epistasis plus localization experiments, single lab, Drosophila ortholog\",\n      \"pmids\": [\"21790556\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Ctdnep1 negatively regulates RANKL-induced osteoclast differentiation; Ctdnep1 knockdown increases phosphorylation of RANKL signaling components and elevates Nfatc1 protein even without RANKL stimulation, and enhances calcium-resorbing activity.\",\n      \"method\": \"siRNA knockdown in RAW264.7 cells, TRAP staining for osteoclast numbers, osteoclast marker gene qPCR, western blot for pRANKL signaling components and Nfatc1, calcium resorption assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — siRNA KD with multiple phenotypic and molecular readouts, single lab, cell line model\",\n      \"pmids\": [\"38749090\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Dullard/Ctdnep1 suppresses BMP signaling in ovarian granulosa cells; conditional deletion leads to hemorrhagic ovarian cysts and upregulation of BMP-inducible inhibitory Smads (Smad6/Smad7); pharmacological rescue with BMP receptor inhibitor LDN-193189 confirmed the mechanism is through BMP signaling.\",\n      \"method\": \"Conditional knockout mouse (Col1a1-Cre and Rosa26-CreER), Smad6/7 gene expression, BMP receptor inhibitor rescue\",\n      \"journal\": \"Genes to cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — inducible KO with pharmacological rescue and molecular readout, single lab\",\n      \"pmids\": [\"29521016\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CTDNEP1 (Dullard) is a non-canonical serine/threonine phosphatase that forms a conserved complex with its activating regulatory subunit NEP1R1 at the inner nuclear/ER membrane; NEP1R1 allosterically activates CTDNEP1 at a site distant from the active site, and together with the scaffold MAN1, the complex dephosphorylates nuclear R-SMADs to terminate TGF-β/BMP superfamily signaling; CTDNEP1 also dephosphorylates lipin1 to regulate phospholipid/ER membrane homeostasis, modulates MYC stability via Ser62 phosphorylation and mitotic fidelity, and interacts with Eps8L2 to organize dorsal actin cables for nuclear positioning during cell migration.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CTDNEP1 (Dullard) is a non-canonical serine/threonine phosphatase that operates at the inner nuclear and ER membrane to terminate TGF-\\u03b2/BMP superfamily signaling and to regulate membrane lipid homeostasis [#0, #3, #4]. Its catalytic activity depends on the regulatory subunit NEP1R1, which binds at a site distant from the active site to allosterically stabilize and activate the enzyme, while a conserved Arg residue in CTDNEP1 orients substrate peptides for dephosphorylation; co-depletion of CTDNEP1 or NEP1R1 produces identical ER expansion phenotypes, defining them as an obligate functional complex [#0]. Together with the inner nuclear membrane scaffold MAN1, the CTDNEP1-NEP1R1 phosphatase dephosphorylates nuclear receptor-regulated SMADs, and disruption of this complex causes accumulation of phosphorylated R-SMADs and aberrant signaling [#2]. This signal-terminating role is conserved and context-dependent: CTDNEP1 dephosphorylates Mad/R-SMADs and promotes BMP receptor turnover in flies and Xenopus [#4, #5], and across mouse tissues its loss elevates pSmad1/5/8 or pSmad2/3 to drive defects in kidney maintenance, endochondral ossification, cardiac outflow tract development, and ovarian function, each rescuable by BMP or TGF-\\u03b2 receptor kinase inhibition [#8, #9, #11, #14]. Independent of signaling termination, CTDNEP1 dephosphorylates lipin1 at its insulin-dependent Ser106 site without requiring an adaptor [#3], stabilizes the genome by limiting MYC Ser62 phosphorylation and modulating mitotic regulators including TOP2A and CHEK1 [#7], and interacts with the actin regulator Eps8L2 to organize dorsal actin cables for nuclear positioning during cell migration [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established that the CTDNEP1 ortholog Dullard restrains BMP signaling, linking its phosphatase activity to receptor turnover and a developmental output.\",\n      \"evidence\": \"Co-IP, phosphatase-dead mutant, and morpholino knockdown with neural marker readout in Xenopus\",\n      \"pmids\": [\"17141153\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct substrate of the phosphatase not defined\", \"Mechanism coupling phosphatase activity to receptor ubiquitination unresolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined CTDNEP1 as a quantitative phosphoserine phosphatase with defined substrate specificity, separating its lipid-regulatory function from signaling roles.\",\n      \"evidence\": \"Steady-state kinetics on phosphoserine nonapeptides corresponding to lipin1 sites\",\n      \"pmids\": [\"21413788\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Activity measured on peptides, not full-length lipin1\", \"Cellular consequences of lipin1 dephosphorylation not addressed here\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Connected Dullard's BMP-modulating role to nuclear envelope and membrane lipid homeostasis, hinting at a membrane-based mechanism for signaling control.\",\n      \"evidence\": \"Genetic interaction with BMP components, pMad western, Importin-\\u03b2/RanGAP localization and lipid staining in Drosophila\",\n      \"pmids\": [\"21790556\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal link between lipid changes and BMP output not established\", \"Ortholog data may not transfer directly to human CTDNEP1\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrated cell-autonomous BMP restraint by Dullard in mammalian organogenesis using pharmacological epistasis.\",\n      \"evidence\": \"Conditional knockout mouse with pSmad1/5/8 staining and LDN-193189 rescue in kidney\",\n      \"pmids\": [\"23360989\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Dullard acts directly on R-SMADs or upstream receptors not distinguished\", \"Substrate identity in vivo unconfirmed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed Dullard can act as a positive modulator of a distinct pathway (WNT/\\u03b2-catenin), revealing context-dependent signaling roles beyond BMP.\",\n      \"evidence\": \"Conditional KO, Wnt3 compound heterozygote epistasis, \\u03b2-catenin reporter, Dvl2 western in germ cell specification\",\n      \"pmids\": [\"23469192\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which Dullard supports Dvl2 levels unknown\", \"Direct substrate in WNT pathway not identified\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Extended Dullard's signaling control to the TGF-\\u03b2/Smad2/3 branch and implicated regulation of R-SMAD protein stability.\",\n      \"evidence\": \"Prx1-Cre conditional KO, pSmad2/3 and total Smad2/3 western, LY-364947 rescue in skeletal development\",\n      \"pmids\": [\"25155999\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking phosphatase to Smad2/3 protein stability unresolved\", \"Direct dephosphorylation of Smad2/3 not shown biochemically\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Provided direct biochemical evidence that Dullard dephosphorylates R-SMADs (Mad) at both C-terminal and linker sites, defining an enzymatic mode of signal termination distinct from degradation.\",\n      \"evidence\": \"Reciprocal Co-IP, phosphatase-dead mutant separating binding from activity, loss-of-function with pMad readout in Drosophila\",\n      \"pmids\": [\"27578171\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human R-SMAD substrate not directly demonstrated here\", \"Role of regulatory subunits in this context not examined\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Confirmed BMP-suppressive role in additional tissue via inducible deletion and pharmacological rescue.\",\n      \"evidence\": \"Inducible/conditional KO mouse, Smad6/7 expression, LDN-193189 rescue in ovarian granulosa cells\",\n      \"pmids\": [\"29521016\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular substrate not identified\", \"Single-lab observation\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed Dullard tunes BMP signaling amplitude to control cell-fate decisions, connecting phosphatase activity to downstream transcriptional programs.\",\n      \"evidence\": \"NCC-specific conditional KO, BMP reporter, pSmad1/5/8 staining, Sema3c/Twist1 expression in cardiac outflow tract\",\n      \"pmids\": [\"32105214\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct substrate in this context not biochemically defined\", \"How signaling amplitude is quantitatively set unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Revealed a non-signaling role for CTDNEP1 in cytoskeletal organization and nuclear positioning through a direct partner.\",\n      \"evidence\": \"Direct interaction assay with Eps8L2, siRNA knockdown with nuclear positioning, migration, and actin cable imaging\",\n      \"pmids\": [\"33567288\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether phosphatase activity is required for the Eps8L2 function not established\", \"Substrate in actin regulation unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Implicated CTDNEP1 in genome stability and oncogenesis by limiting MYC phosphorylation and modulating mitotic regulators.\",\n      \"evidence\": \"Ctdnep1 KO mouse tumor model, phosphoproteomics, pSer62-MYC western, chromosomal instability assays, co-targeting MYC/CHEK1\",\n      \"pmids\": [\"36765089\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CTDNEP1 directly dephosphorylates MYC Ser62 not shown\", \"Direct vs indirect modulation of TOP2A/CHEK1 unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Resolved the structural and mechanistic basis of CTDNEP1 activation, defining NEP1R1 as an allosteric activating subunit and a conserved Arg as the substrate-orienting residue.\",\n      \"evidence\": \"X-ray crystallography of CTDNEP1-NEP1R1 with pseudosubstrate, in vitro phosphatase assays, mutagenesis, ER morphology readout\",\n      \"pmids\": [\"38776370\", \"38045299\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological substrate repertoire engaged by the activated complex not fully enumerated\", \"Regulation of complex assembly in vivo unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Integrated the phosphatase complex with the scaffold MAN1 to provide a molecular mechanism for nuclear R-SMAD dephosphorylation and signal termination.\",\n      \"evidence\": \"Domain mapping, structural prediction, mutagenesis, Co-IP, phosphoproteomics, TGF-\\u03b2 signaling assays (preprint)\",\n      \"pmids\": [\"bio_10.1101_2024.09.23.614427\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Preprint; peer review pending\", \"Quantitative contribution of MAN1 recruitment vs intrinsic activity not separated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrated CTDNEP1 negatively regulates osteoclast differentiation, broadening its tissue-level roles in signaling restraint.\",\n      \"evidence\": \"siRNA knockdown in RAW264.7 cells, TRAP staining, marker qPCR, pRANKL/Nfatc1 western, calcium resorption assay\",\n      \"pmids\": [\"38749090\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct substrate in RANKL pathway not identified\", \"Single cell-line model\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how a single phosphatase complex coordinates its distinct substrate sets — R-SMADs, lipin1, MYC, and mitotic regulators — and how substrate selection is controlled across membrane compartments and tissues.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model of substrate selection\", \"Spatial regulation between nuclear envelope and ER pools unclear\", \"Direct in vivo human substrates largely inferred rather than demonstrated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 3, 4, 5, 7]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005635\", \"supporting_discovery_ids\": [6, 11]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 4, 5, 8, 9, 11]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [8, 9, 10, 11]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [7]}\n    ],\n    \"complexes\": [\n      \"CTDNEP1-NEP1R1 phosphatase complex\",\n      \"CTDNEP1-NEP1R1-MAN1 complex\"\n    ],\n    \"partners\": [\n      \"NEP1R1\",\n      \"MAN1\",\n      \"Eps8L2\",\n      \"BMPRII\",\n      \"Mad\",\n      \"lipin1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}