{"gene":"CNOT8","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2001,"finding":"Human CNOT8 (hCAF1/hPOP2) binds to the human CCR4 ortholog (hCCR4) via its leucine-rich repeat (LRR) domain, as demonstrated by two-hybrid and far-Western assays, indicating conservation of the CCR4-NOT complex from yeast to human.","method":"Two-hybrid assay, far-Western assay","journal":"BMC genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal methods (two-hybrid and far-Western) in a single study; binding partner and domain requirement established","pmids":["11747467"],"is_preprint":false},{"year":2007,"finding":"CNOT8 (hCAF1) interacts with PRMT1 in vivo and co-localizes with PRMT1 in nuclear speckles; CNOT8 is not a substrate for PRMT1-mediated methylation but regulates PRMT1 activity in a substrate-dependent manner, modulating methylation of Sam68 and histone H4.","method":"Co-immunoprecipitation, immunofluorescence, in vitro methylation assay, siRNA knockdown","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus in vitro activity assay plus siRNA functional follow-up, single lab, multiple orthogonal methods","pmids":["17264152"],"is_preprint":false},{"year":2007,"finding":"The Tob-hCaf1 (CNOT8) complex was crystallized and yielded crystals diffracting to ~2.6 Å, establishing that Tob and intact hCaf1 form a heterodimer amenable to structural analysis.","method":"Co-expression in E. coli, co-purification, co-crystallization, X-ray diffraction","journal":"Acta crystallographica Section F","confidence":"Low","confidence_rationale":"Tier 1 / Weak — preliminary crystallographic report; structure not yet solved in this paper, single method, no functional validation","pmids":["18084094"],"is_preprint":false},{"year":2009,"finding":"Crystal structure of the Tob N-terminal region bound to hCaf1 (CNOT8) revealed that hCaf1 most closely resembles the catalytic domain of yeast Pop2 and human PARN; both Box A and Box B of Tob mediate the association. Cell growth assays showed that deadenylase activity of Caf1 is not critical, but complex formation with Tob is crucial for cell growth inhibition.","method":"X-ray crystallography, cell growth assays with wild-type and mutant proteins","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus mutant functional assays in the same study, rigorous mechanistic dissection of interface and activity requirements","pmids":["19276069"],"is_preprint":false},{"year":2009,"finding":"CNOT8 (hPop2/Caf1b) possesses deadenylase activity mediated by its DEDD nuclease domain. Knockdown of CNOT8 alone reduces cell proliferation, and combined knockdown of CNOT7 and CNOT8 further reduces proliferation, indicating partial functional redundancy. CNOT8 knockdown also de-represses antiproliferative genes MSMB and PMP22.","method":"siRNA knockdown, cell proliferation assays, gene expression profiling","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with defined proliferation phenotype and gene expression readouts, single lab, multiple cell-based assays","pmids":["19605561"],"is_preprint":false},{"year":2012,"finding":"The anti-proliferative activity of BTG/TOB proteins (BTG2, TOB1) requires direct interaction with Caf1a (CNOT7) and Caf1b (CNOT8); a BTG2/TOB1 mutant unable to bind Caf1a/Caf1b loses anti-proliferative activity and loses the ability to regulate mRNA abundance and translation. This regulation does not require other CCR4-NOT subunits including CNOT6/CNOT6L, CNOT1, or CNOT3.","method":"Mutagenesis, co-immunoprecipitation, cell proliferation assays, mRNA abundance and translation assays, siRNA knockdown","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — interface mutagenesis combined with multiple functional readouts (proliferation, mRNA, translation), epistasis analysis placing CNOT8 downstream of BTG/TOB, replicated across multiple BTG/TOB family members","pmids":["23236473"],"is_preprint":false},{"year":2013,"finding":"CNOT7/hCAF1 (note: the paper studies hCAF1/CNOT7 but the corpus query covers both paralogs; this finding is specifically attributed to CNOT7, not CNOT8) — excluded per gene-specificity rule. See note: paper PMID:23386060 focuses specifically on CNOT7, not CNOT8.","method":"N/A","journal":"The EMBO journal","confidence":"Low","confidence_rationale":"Excluded — findings attributed to CNOT7 paralog, not CNOT8","pmids":["23386060"],"is_preprint":false},{"year":2014,"finding":"CNOT7/hCAF1 (specifically named CNOT7) is involved in TTP-mediated deadenylation of ICAM-1 and IL-8 mRNAs; TTP, CNOT7, and CNOT1 are co-immunoprecipitated together. CNOT7 silencing stabilizes ICAM-1 and IL-8 mRNAs and increases their protein production.","method":"Co-immunoprecipitation, siRNA knockdown, mRNA stability assays, ELISA","journal":"Cellular signalling","confidence":"Low","confidence_rationale":"Tier 3 / Weak — paper explicitly names CNOT7, not CNOT8; finding is attributed to the paralog; single lab, single Co-IP","pmids":["25038453"],"is_preprint":false},{"year":2020,"finding":"CNOT8 depletion in HeLa cells increases γH2AX, RPA, 53BP1, and RAD51 foci formation following ionizing radiation, and slightly alters phosphorylation of DNA damage response proteins, indicating CNOT8 is involved in the DNA damage response.","method":"siRNA knockdown, immunofluorescence (foci formation), western blotting of phospho-DDR proteins, cell viability assay","journal":"Reports of biochemistry & molecular biology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, descriptive foci assay without mechanistic pathway placement, no rescue experiment","pmids":["33178865"],"is_preprint":false},{"year":2022,"finding":"CNOT7 outcompetes CNOT8 for integration into the CCR4-NOT complex by showing greater affinity for the scaffold subunit CNOT1; CNOT7 can block CNOT8 from binding CNOT1. CNOT8 protein (but not mRNA) increases upon CNOT7 depletion due to increased incorporation into CCR4-NOT, which stabilizes CNOT8 protein. CNOT8 protein is intrinsically less stable than CNOT7.","method":"siRNA knockdown, co-immunoprecipitation, western blotting, mRNA stability assay, polysome profiling","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus multiple biochemical approaches (protein stability, mRNA stability, translation) in single lab establishing competitive integration mechanism","pmids":["35248544"],"is_preprint":false},{"year":2022,"finding":"Cnot8 knockout in mouse ESCs causes deadenylation defects—increased poly(A) tail lengths and mRNA half-lives of target transcripts including naïve-state genes—and blocks the naïve-to-formative pluripotency transition. The function requires both deadenylase activity and interaction with the CCR4-NOT complex, as well as binding to Tob1 and Pabpc1.","method":"CRISPR knockout, poly(A) tail length assay, mRNA stability assay, co-immunoprecipitation (Tob1, Pabpc1), rescue by knockdown of target genes, embryo lethality observation","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with multiple orthogonal functional readouts (poly(A) tail, mRNA stability, differentiation), binding partner identification by Co-IP, rescue experiments, single rigorous study","pmids":["35390160"],"is_preprint":false},{"year":2024,"finding":"CNOT8, but not CNOT7, interacts with MSI2 (an RNA-binding protein) that binds to Prdx4 mRNA in pancreatic β cells; this interaction is associated with post-transcriptional regulation of Prdx4 expression. CNOT8 protein increases in Cnot7-KO β cells.","method":"Co-immunoprecipitation (CNOT8-MSI2), RNA immunoprecipitation (MSI2-Prdx4 mRNA), western blotting","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — preprint, single Co-IP identifying MSI2 as a binding partner, functional consequence of CNOT8-MSI2 interaction not directly tested for CNOT8 specifically","pmids":["bio_10.1101_2024.06.26.599433"],"is_preprint":true},{"year":2025,"finding":"Loss of Cnot8 in mouse gastruloids causes widespread poly(A) tail elongation and transcript stabilization, shifting mesoderm differentiation toward ectopic notochord fate and profoundly impacting axial patterning, establishing Cnot8 deadenylase activity as essential for germ layer specification during mammalian body plan formation.","method":"CRISPR screen, single-cell transcriptomics, poly(A) tail length profiling, gastruloid differentiation assay","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — preprint combining CRISPR KO with single-cell transcriptomics and poly(A) tail profiling; multiple orthogonal methods but not yet peer-reviewed","pmids":["bio_10.1101_2025.07.22.666114"],"is_preprint":true}],"current_model":"CNOT8 (hCAF1/CALIF) is a DEDD-family deadenylase subunit of the CCR4-NOT complex that removes poly(A) tails from target mRNAs; it binds the scaffold subunit CNOT1 (with lower affinity than its paralog CNOT7, which can competitively displace it), interacts with BTG/TOB antiproliferative proteins via their Box A and Box B motifs to mediate mRNA decay and translational repression, associates with PRMT1 to regulate arginine methylation of substrates, and binds Tob1, Pabpc1, and (uniquely among the two paralogs) MSI2; loss of CNOT8 deadenylase activity leads to poly(A) tail elongation, mRNA stabilization, impaired naïve-to-formative pluripotency transition, defective mesoderm specification, and altered DNA damage responses."},"narrative":{"mechanistic_narrative":"CNOT8 (hCAF1/hPOP2) is a DEDD-family deadenylase subunit of the CCR4-NOT complex that shortens mRNA poly(A) tails to drive transcript decay and post-transcriptional gene regulation [PMID:19605561, PMID:35390160]. Its catalytic domain most closely resembles yeast Pop2 and human PARN, and it associates with the conserved CCR4-NOT machinery through binding to the human CCR4 ortholog via its LRR domain [PMID:11747467, PMID:19276069]. CNOT8 occupies the complex in competition with its paralog CNOT7, which binds the scaffold subunit CNOT1 with higher affinity and can displace CNOT8; incorporation into CCR4-NOT stabilizes the otherwise intrinsically labile CNOT8 protein [PMID:35248544]. CNOT8 is recruited to specific transcripts by the antiproliferative BTG/TOB proteins, which engage hCaf1 through their Box A and Box B motifs; this physical interaction—rather than deadenylase activity per se—is required for BTG/TOB-mediated growth inhibition, mRNA destabilization, and translational repression [PMID:19276069, PMID:23236473]. Through its deadenylase function CNOT8 controls developmental gene expression programs: its loss elongates poly(A) tails and stabilizes target mRNAs, blocking the naïve-to-formative pluripotency transition (dependent on CCR4-NOT integration and binding to Tob1 and Pabpc1) and distorting mesoderm specification and axial patterning during gastrulation [PMID:35390160, PMID:bio_10.1101_2025.07.22.666114]. CNOT8 additionally interacts with PRMT1 in nuclear speckles to modulate its substrate-specific arginine methylation activity and is implicated in the ionizing-radiation DNA damage response [PMID:17264152, PMID:33178865].","teleology":[{"year":2001,"claim":"Established that human CNOT8 is a bona fide CCR4-NOT component, defining the LRR domain as the determinant of its association with human CCR4 and demonstrating conservation of the complex from yeast to human.","evidence":"two-hybrid and far-Western assays mapping the hCCR4-binding LRR domain","pmids":["11747467"],"confidence":"Medium","gaps":["Did not test deadenylase activity or assembly with other CCR4-NOT subunits","No structural or affinity quantification of the interaction"]},{"year":2007,"claim":"Linked CNOT8 to protein arginine methylation by showing it binds and modulates PRMT1 activity, broadening its role beyond mRNA decay.","evidence":"reciprocal Co-IP, nuclear speckle co-localization, in vitro methylation assay, and siRNA knockdown","pmids":["17264152"],"confidence":"Medium","gaps":["Mechanism by which CNOT8 alters PRMT1 substrate selectivity is undefined","Connection between methylation regulation and deadenylase function not established"]},{"year":2009,"claim":"Defined the structural basis for CNOT8 recruitment by antiproliferative TOB and showed that complex formation, not catalysis, drives growth inhibition.","evidence":"crystal structure of Tob N-terminus bound to hCaf1 plus cell growth assays with catalytic and interface mutants","pmids":["19276069"],"confidence":"High","gaps":["Full Tob-hCaf1 complex with substrate not captured","How TOB binding alters target selection on mRNA unresolved"]},{"year":2009,"claim":"Demonstrated CNOT8 is a catalytically active deadenylase with partial redundancy with CNOT7, and that it represses antiproliferative target genes.","evidence":"siRNA single and double knockdown, proliferation assays, and expression profiling identifying MSMB and PMP22 de-repression","pmids":["19605561"],"confidence":"Medium","gaps":["Direct deadenylation of named targets not biochemically reconstituted","Extent of CNOT7/CNOT8 redundancy not quantified at transcript level"]},{"year":2012,"claim":"Placed CNOT8 downstream of BTG/TOB as the obligatory effector of their antiproliferative and mRNA-regulatory activity, independent of other CCR4-NOT subunits.","evidence":"interface mutagenesis, Co-IP, proliferation, mRNA abundance and translation assays across multiple BTG/TOB members","pmids":["23236473"],"confidence":"High","gaps":["Specific mRNA targets of the BTG/TOB-CNOT8 module not enumerated","Whether deadenylase activity is dispensable in this context not fully separated from CNOT7 contribution"]},{"year":2020,"claim":"Implicated CNOT8 in the DNA damage response by showing its depletion alters damage-marker foci after ionizing radiation.","evidence":"siRNA knockdown, foci immunofluorescence (γH2AX, RPA, 53BP1, RAD51), phospho-DDR western blotting","pmids":["33178865"],"confidence":"Low","gaps":["Descriptive foci assay without rescue or pathway placement","No mRNA target linking deadenylation to DDR identified"]},{"year":2022,"claim":"Revealed that paralog competition governs CNOT8 abundance in the complex—CNOT7 outcompetes CNOT8 for CNOT1, and incorporation stabilizes the intrinsically labile CNOT8 protein.","evidence":"reciprocal Co-IP, knockdown, protein and mRNA stability assays, polysome profiling","pmids":["35248544"],"confidence":"Medium","gaps":["Structural basis of the CNOT1 affinity difference not solved","Functional consequences of paralog swapping on specific transcripts unclear"]},{"year":2022,"claim":"Established CNOT8 deadenylase activity as essential for the naïve-to-formative pluripotency transition, requiring CCR4-NOT integration and binding to Tob1 and Pabpc1.","evidence":"CRISPR knockout in mouse ESCs, poly(A) tail and mRNA half-life measurements, Co-IP, target-gene knockdown rescue","pmids":["35390160"],"confidence":"High","gaps":["Which transcripts are direct versus indirect targets not fully resolved","Relative contribution of CNOT7 redundancy in vivo not addressed"]},{"year":2024,"claim":"Identified MSI2 as a paralog-specific CNOT8 partner connecting it to post-transcriptional control of Prdx4 in pancreatic β cells.","evidence":"Co-IP (CNOT8-MSI2), RNA-IP (MSI2-Prdx4 mRNA), western blotting (preprint)","pmids":["bio_10.1101_2024.06.26.599433"],"confidence":"Low","gaps":["Single Co-IP without reciprocal validation; functional consequence of the CNOT8-MSI2 interaction not directly tested for CNOT8","Preprint, not peer-reviewed"]},{"year":2025,"claim":"Extended CNOT8 deadenylase function to mammalian body plan formation, showing its loss elongates poly(A) tails and redirects mesoderm toward ectopic notochord fate.","evidence":"CRISPR screen, single-cell transcriptomics, poly(A) tail profiling in gastruloids (preprint)","pmids":["bio_10.1101_2025.07.22.666114"],"confidence":"Medium","gaps":["Direct target transcripts driving the fate shift not pinpointed","Preprint, not peer-reviewed"]},{"year":null,"claim":"How CNOT8 versus CNOT7 substrate selectivity is encoded, and how its diverse partners (TOB/BTG, PRMT1, MSI2) direct it to distinct transcript pools across cell types, remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No transcriptome-wide map distinguishing CNOT8- from CNOT7-specific targets","No structure of CNOT8 engaging a poly(A) substrate within CCR4-NOT","Mechanistic link between deadenylation and the DDR phenotype undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[3,4,10]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[4,10]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[10]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[4,10]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[10,12]}],"complexes":["CCR4-NOT"],"partners":["CNOT1","CNOT7","TOB1","BTG2","PABPC1","PRMT1","MSI2","CCR4"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UFF9","full_name":"CCR4-NOT transcription complex subunit 8","aliases":["CAF1-like protein","CALIFp","CAF2","CCR4-associated factor 8","Caf1b"],"length_aa":292,"mass_kda":33.5,"function":"Has 3'-5' poly(A) exoribonuclease activity for synthetic poly(A) RNA substrate. Its function seems to be partially redundant with that of CNOT7. Catalytic component of the CCR4-NOT complex which is linked to various cellular processes including bulk mRNA degradation, miRNA-mediated repression, translational repression during translational initiation and general transcription regulation. During miRNA-mediated repression the complex also seems to act as translational repressor during translational initiation. Additional complex functions may be a consequence of its influence on mRNA expression. Associates with members of the BTG family such as TOB1 and BTG2 and is required for their anti-proliferative activity","subcellular_location":"Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9UFF9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CNOT8","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CAPZB","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/CNOT8","total_profiled":1310},"omim":[{"mim_id":"608229","title":"NANOS C2HC-TYPE ZINC FINGER 3; NANOS3","url":"https://www.omim.org/entry/608229"},{"mim_id":"608228","title":"NANOS C2HC-TYPE ZINC FINGER 2; NANOS2","url":"https://www.omim.org/entry/608228"},{"mim_id":"603731","title":"CCR4-NOT TRANSCRIPTION COMPLEX, SUBUNIT 8; CNOT8","url":"https://www.omim.org/entry/603731"},{"mim_id":"153550","title":"CHROMOSOME 5q DELETION SYNDROME","url":"https://www.omim.org/entry/153550"}],"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/CNOT8"},"hgnc":{"alias_symbol":["CAF1","hCAF1","CALIF"],"prev_symbol":["POP2"]},"alphafold":{"accession":"Q9UFF9","domains":[{"cath_id":"3.30.420.10","chopping":"11-269","consensus_level":"high","plddt":95.3007,"start":11,"end":269}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UFF9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UFF9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UFF9-F1-predicted_aligned_error_v6.png","plddt_mean":90.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CNOT8","jax_strain_url":"https://www.jax.org/strain/search?query=CNOT8"},"sequence":{"accession":"Q9UFF9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UFF9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UFF9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UFF9"}},"corpus_meta":[{"pmid":"9422084","id":"PMC_9422084","title":"Summary report on the ISOBM TD-4 Workshop: analysis of 56 monoclonal antibodies against the MUC1 mucin. San Diego, Calif., November 17-23, 1996.","date":"1998","source":"Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/9422084","citation_count":198,"is_preprint":false},{"pmid":"11747467","id":"PMC_11747467","title":"Identification of four families of yCCR4- and Mg2+-dependent endonuclease-related proteins in higher eukaryotes, and characterization of orthologs of yCCR4 with a conserved leucine-rich repeat essential for hCAF1/hPOP2 binding.","date":"2001","source":"BMC genomics","url":"https://pubmed.ncbi.nlm.nih.gov/11747467","citation_count":113,"is_preprint":false},{"pmid":"19605561","id":"PMC_19605561","title":"The Ccr4-NOT deadenylase subunits CNOT7 and CNOT8 have overlapping roles and modulate cell proliferation.","date":"2009","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/19605561","citation_count":97,"is_preprint":false},{"pmid":"19276069","id":"PMC_19276069","title":"Structural basis for the antiproliferative activity of the Tob-hCaf1 complex.","date":"2009","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19276069","citation_count":90,"is_preprint":false},{"pmid":"23236473","id":"PMC_23236473","title":"The anti-proliferative activity of BTG/TOB proteins is mediated via the Caf1a (CNOT7) and Caf1b (CNOT8) deadenylase subunits of the Ccr4-not complex.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23236473","citation_count":64,"is_preprint":false},{"pmid":"17264152","id":"PMC_17264152","title":"hCAF1, a new regulator of PRMT1-dependent arginine methylation.","date":"2007","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/17264152","citation_count":62,"is_preprint":false},{"pmid":"23386060","id":"PMC_23386060","title":"hCAF1/CNOT7 regulates interferon signalling by targeting STAT1.","date":"2013","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/23386060","citation_count":28,"is_preprint":false},{"pmid":"25038453","id":"PMC_25038453","title":"CNOT7/hCAF1 is involved in ICAM-1 and IL-8 regulation by tristetraprolin.","date":"2014","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/25038453","citation_count":14,"is_preprint":false},{"pmid":"35248544","id":"PMC_35248544","title":"CNOT7 Outcompetes Its Paralog CNOT8 for Integration into The CCR4-NOT Complex.","date":"2022","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/35248544","citation_count":10,"is_preprint":false},{"pmid":"16786164","id":"PMC_16786164","title":"Insulin-like growth factor I differentially regulates the expression of HIRF1/hCAF1 and BTG1 genes in human MCF-7 breast cancer cells.","date":"2006","source":"International journal of molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/16786164","citation_count":10,"is_preprint":false},{"pmid":"35390160","id":"PMC_35390160","title":"Cnot8 eliminates naïve regulation networks and is essential for naïve-to-formative pluripotency transition.","date":"2022","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/35390160","citation_count":6,"is_preprint":false},{"pmid":"18084094","id":"PMC_18084094","title":"Crystallization and preliminary crystallographic analysis of the Tob-hCaf1 complex.","date":"2007","source":"Acta crystallographica. Section F, Structural biology and crystallization communications","url":"https://pubmed.ncbi.nlm.nih.gov/18084094","citation_count":4,"is_preprint":false},{"pmid":"33178865","id":"PMC_33178865","title":"Importance of CNOT8 Deadenylase Subunit in DNA Damage Responses Following Ionizing Radiation (IR).","date":"2020","source":"Reports of biochemistry & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/33178865","citation_count":3,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.07.22.666114","title":"Regulation of mRNA polyadenylation governs mammalian body plan formation in gastruloids","date":"2025-07-22","source":"bioRxiv","url":"https://doi.org/10.1101/2025.07.22.666114","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.06.26.599433","title":"Post-transcriptional regulation by the CCR4-NOT deadenylase complex maintains redox homeostasis in insulin biosynthesis in mouse pancreatic β cells","date":"2024-06-29","source":"bioRxiv","url":"https://doi.org/10.1101/2024.06.26.599433","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9497,"output_tokens":3308,"usd":0.039055,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10783,"output_tokens":3445,"usd":0.07002,"stage2_stop_reason":"end_turn"},"total_usd":0.109075,"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\": 2001,\n      \"finding\": \"Human CNOT8 (hCAF1/hPOP2) binds to the human CCR4 ortholog (hCCR4) via its leucine-rich repeat (LRR) domain, as demonstrated by two-hybrid and far-Western assays, indicating conservation of the CCR4-NOT complex from yeast to human.\",\n      \"method\": \"Two-hybrid assay, far-Western assay\",\n      \"journal\": \"BMC genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal methods (two-hybrid and far-Western) in a single study; binding partner and domain requirement established\",\n      \"pmids\": [\"11747467\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CNOT8 (hCAF1) interacts with PRMT1 in vivo and co-localizes with PRMT1 in nuclear speckles; CNOT8 is not a substrate for PRMT1-mediated methylation but regulates PRMT1 activity in a substrate-dependent manner, modulating methylation of Sam68 and histone H4.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, in vitro methylation assay, siRNA knockdown\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus in vitro activity assay plus siRNA functional follow-up, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"17264152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"The Tob-hCaf1 (CNOT8) complex was crystallized and yielded crystals diffracting to ~2.6 Å, establishing that Tob and intact hCaf1 form a heterodimer amenable to structural analysis.\",\n      \"method\": \"Co-expression in E. coli, co-purification, co-crystallization, X-ray diffraction\",\n      \"journal\": \"Acta crystallographica Section F\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 1 / Weak — preliminary crystallographic report; structure not yet solved in this paper, single method, no functional validation\",\n      \"pmids\": [\"18084094\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Crystal structure of the Tob N-terminal region bound to hCaf1 (CNOT8) revealed that hCaf1 most closely resembles the catalytic domain of yeast Pop2 and human PARN; both Box A and Box B of Tob mediate the association. Cell growth assays showed that deadenylase activity of Caf1 is not critical, but complex formation with Tob is crucial for cell growth inhibition.\",\n      \"method\": \"X-ray crystallography, cell growth assays with wild-type and mutant proteins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus mutant functional assays in the same study, rigorous mechanistic dissection of interface and activity requirements\",\n      \"pmids\": [\"19276069\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CNOT8 (hPop2/Caf1b) possesses deadenylase activity mediated by its DEDD nuclease domain. Knockdown of CNOT8 alone reduces cell proliferation, and combined knockdown of CNOT7 and CNOT8 further reduces proliferation, indicating partial functional redundancy. CNOT8 knockdown also de-represses antiproliferative genes MSMB and PMP22.\",\n      \"method\": \"siRNA knockdown, cell proliferation assays, gene expression profiling\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with defined proliferation phenotype and gene expression readouts, single lab, multiple cell-based assays\",\n      \"pmids\": [\"19605561\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The anti-proliferative activity of BTG/TOB proteins (BTG2, TOB1) requires direct interaction with Caf1a (CNOT7) and Caf1b (CNOT8); a BTG2/TOB1 mutant unable to bind Caf1a/Caf1b loses anti-proliferative activity and loses the ability to regulate mRNA abundance and translation. This regulation does not require other CCR4-NOT subunits including CNOT6/CNOT6L, CNOT1, or CNOT3.\",\n      \"method\": \"Mutagenesis, co-immunoprecipitation, cell proliferation assays, mRNA abundance and translation assays, siRNA knockdown\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — interface mutagenesis combined with multiple functional readouts (proliferation, mRNA, translation), epistasis analysis placing CNOT8 downstream of BTG/TOB, replicated across multiple BTG/TOB family members\",\n      \"pmids\": [\"23236473\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"CNOT7/hCAF1 (note: the paper studies hCAF1/CNOT7 but the corpus query covers both paralogs; this finding is specifically attributed to CNOT7, not CNOT8) — excluded per gene-specificity rule. See note: paper PMID:23386060 focuses specifically on CNOT7, not CNOT8.\",\n      \"method\": \"N/A\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Excluded — findings attributed to CNOT7 paralog, not CNOT8\",\n      \"pmids\": [\"23386060\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CNOT7/hCAF1 (specifically named CNOT7) is involved in TTP-mediated deadenylation of ICAM-1 and IL-8 mRNAs; TTP, CNOT7, and CNOT1 are co-immunoprecipitated together. CNOT7 silencing stabilizes ICAM-1 and IL-8 mRNAs and increases their protein production.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, mRNA stability assays, ELISA\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — paper explicitly names CNOT7, not CNOT8; finding is attributed to the paralog; single lab, single Co-IP\",\n      \"pmids\": [\"25038453\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CNOT8 depletion in HeLa cells increases γH2AX, RPA, 53BP1, and RAD51 foci formation following ionizing radiation, and slightly alters phosphorylation of DNA damage response proteins, indicating CNOT8 is involved in the DNA damage response.\",\n      \"method\": \"siRNA knockdown, immunofluorescence (foci formation), western blotting of phospho-DDR proteins, cell viability assay\",\n      \"journal\": \"Reports of biochemistry & molecular biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, descriptive foci assay without mechanistic pathway placement, no rescue experiment\",\n      \"pmids\": [\"33178865\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CNOT7 outcompetes CNOT8 for integration into the CCR4-NOT complex by showing greater affinity for the scaffold subunit CNOT1; CNOT7 can block CNOT8 from binding CNOT1. CNOT8 protein (but not mRNA) increases upon CNOT7 depletion due to increased incorporation into CCR4-NOT, which stabilizes CNOT8 protein. CNOT8 protein is intrinsically less stable than CNOT7.\",\n      \"method\": \"siRNA knockdown, co-immunoprecipitation, western blotting, mRNA stability assay, polysome profiling\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus multiple biochemical approaches (protein stability, mRNA stability, translation) in single lab establishing competitive integration mechanism\",\n      \"pmids\": [\"35248544\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cnot8 knockout in mouse ESCs causes deadenylation defects—increased poly(A) tail lengths and mRNA half-lives of target transcripts including naïve-state genes—and blocks the naïve-to-formative pluripotency transition. The function requires both deadenylase activity and interaction with the CCR4-NOT complex, as well as binding to Tob1 and Pabpc1.\",\n      \"method\": \"CRISPR knockout, poly(A) tail length assay, mRNA stability assay, co-immunoprecipitation (Tob1, Pabpc1), rescue by knockdown of target genes, embryo lethality observation\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with multiple orthogonal functional readouts (poly(A) tail, mRNA stability, differentiation), binding partner identification by Co-IP, rescue experiments, single rigorous study\",\n      \"pmids\": [\"35390160\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CNOT8, but not CNOT7, interacts with MSI2 (an RNA-binding protein) that binds to Prdx4 mRNA in pancreatic β cells; this interaction is associated with post-transcriptional regulation of Prdx4 expression. CNOT8 protein increases in Cnot7-KO β cells.\",\n      \"method\": \"Co-immunoprecipitation (CNOT8-MSI2), RNA immunoprecipitation (MSI2-Prdx4 mRNA), western blotting\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — preprint, single Co-IP identifying MSI2 as a binding partner, functional consequence of CNOT8-MSI2 interaction not directly tested for CNOT8 specifically\",\n      \"pmids\": [\"bio_10.1101_2024.06.26.599433\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Loss of Cnot8 in mouse gastruloids causes widespread poly(A) tail elongation and transcript stabilization, shifting mesoderm differentiation toward ectopic notochord fate and profoundly impacting axial patterning, establishing Cnot8 deadenylase activity as essential for germ layer specification during mammalian body plan formation.\",\n      \"method\": \"CRISPR screen, single-cell transcriptomics, poly(A) tail length profiling, gastruloid differentiation assay\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — preprint combining CRISPR KO with single-cell transcriptomics and poly(A) tail profiling; multiple orthogonal methods but not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.07.22.666114\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"CNOT8 (hCAF1/CALIF) is a DEDD-family deadenylase subunit of the CCR4-NOT complex that removes poly(A) tails from target mRNAs; it binds the scaffold subunit CNOT1 (with lower affinity than its paralog CNOT7, which can competitively displace it), interacts with BTG/TOB antiproliferative proteins via their Box A and Box B motifs to mediate mRNA decay and translational repression, associates with PRMT1 to regulate arginine methylation of substrates, and binds Tob1, Pabpc1, and (uniquely among the two paralogs) MSI2; loss of CNOT8 deadenylase activity leads to poly(A) tail elongation, mRNA stabilization, impaired naïve-to-formative pluripotency transition, defective mesoderm specification, and altered DNA damage responses.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CNOT8 (hCAF1/hPOP2) is a DEDD-family deadenylase subunit of the CCR4-NOT complex that shortens mRNA poly(A) tails to drive transcript decay and post-transcriptional gene regulation [#4, #10]. Its catalytic domain most closely resembles yeast Pop2 and human PARN, and it associates with the conserved CCR4-NOT machinery through binding to the human CCR4 ortholog via its LRR domain [#0, #3]. CNOT8 occupies the complex in competition with its paralog CNOT7, which binds the scaffold subunit CNOT1 with higher affinity and can displace CNOT8; incorporation into CCR4-NOT stabilizes the otherwise intrinsically labile CNOT8 protein [#9]. CNOT8 is recruited to specific transcripts by the antiproliferative BTG/TOB proteins, which engage hCaf1 through their Box A and Box B motifs; this physical interaction—rather than deadenylase activity per se—is required for BTG/TOB-mediated growth inhibition, mRNA destabilization, and translational repression [#3, #5]. Through its deadenylase function CNOT8 controls developmental gene expression programs: its loss elongates poly(A) tails and stabilizes target mRNAs, blocking the naïve-to-formative pluripotency transition (dependent on CCR4-NOT integration and binding to Tob1 and Pabpc1) and distorting mesoderm specification and axial patterning during gastrulation [#10, #12]. CNOT8 additionally interacts with PRMT1 in nuclear speckles to modulate its substrate-specific arginine methylation activity and is implicated in the ionizing-radiation DNA damage response [#1, #8].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Established that human CNOT8 is a bona fide CCR4-NOT component, defining the LRR domain as the determinant of its association with human CCR4 and demonstrating conservation of the complex from yeast to human.\",\n      \"evidence\": \"two-hybrid and far-Western assays mapping the hCCR4-binding LRR domain\",\n      \"pmids\": [\"11747467\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not test deadenylase activity or assembly with other CCR4-NOT subunits\", \"No structural or affinity quantification of the interaction\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Linked CNOT8 to protein arginine methylation by showing it binds and modulates PRMT1 activity, broadening its role beyond mRNA decay.\",\n      \"evidence\": \"reciprocal Co-IP, nuclear speckle co-localization, in vitro methylation assay, and siRNA knockdown\",\n      \"pmids\": [\"17264152\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which CNOT8 alters PRMT1 substrate selectivity is undefined\", \"Connection between methylation regulation and deadenylase function not established\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Defined the structural basis for CNOT8 recruitment by antiproliferative TOB and showed that complex formation, not catalysis, drives growth inhibition.\",\n      \"evidence\": \"crystal structure of Tob N-terminus bound to hCaf1 plus cell growth assays with catalytic and interface mutants\",\n      \"pmids\": [\"19276069\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full Tob-hCaf1 complex with substrate not captured\", \"How TOB binding alters target selection on mRNA unresolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstrated CNOT8 is a catalytically active deadenylase with partial redundancy with CNOT7, and that it represses antiproliferative target genes.\",\n      \"evidence\": \"siRNA single and double knockdown, proliferation assays, and expression profiling identifying MSMB and PMP22 de-repression\",\n      \"pmids\": [\"19605561\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct deadenylation of named targets not biochemically reconstituted\", \"Extent of CNOT7/CNOT8 redundancy not quantified at transcript level\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Placed CNOT8 downstream of BTG/TOB as the obligatory effector of their antiproliferative and mRNA-regulatory activity, independent of other CCR4-NOT subunits.\",\n      \"evidence\": \"interface mutagenesis, Co-IP, proliferation, mRNA abundance and translation assays across multiple BTG/TOB members\",\n      \"pmids\": [\"23236473\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific mRNA targets of the BTG/TOB-CNOT8 module not enumerated\", \"Whether deadenylase activity is dispensable in this context not fully separated from CNOT7 contribution\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Implicated CNOT8 in the DNA damage response by showing its depletion alters damage-marker foci after ionizing radiation.\",\n      \"evidence\": \"siRNA knockdown, foci immunofluorescence (γH2AX, RPA, 53BP1, RAD51), phospho-DDR western blotting\",\n      \"pmids\": [\"33178865\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Descriptive foci assay without rescue or pathway placement\", \"No mRNA target linking deadenylation to DDR identified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Revealed that paralog competition governs CNOT8 abundance in the complex—CNOT7 outcompetes CNOT8 for CNOT1, and incorporation stabilizes the intrinsically labile CNOT8 protein.\",\n      \"evidence\": \"reciprocal Co-IP, knockdown, protein and mRNA stability assays, polysome profiling\",\n      \"pmids\": [\"35248544\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of the CNOT1 affinity difference not solved\", \"Functional consequences of paralog swapping on specific transcripts unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established CNOT8 deadenylase activity as essential for the naïve-to-formative pluripotency transition, requiring CCR4-NOT integration and binding to Tob1 and Pabpc1.\",\n      \"evidence\": \"CRISPR knockout in mouse ESCs, poly(A) tail and mRNA half-life measurements, Co-IP, target-gene knockdown rescue\",\n      \"pmids\": [\"35390160\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which transcripts are direct versus indirect targets not fully resolved\", \"Relative contribution of CNOT7 redundancy in vivo not addressed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified MSI2 as a paralog-specific CNOT8 partner connecting it to post-transcriptional control of Prdx4 in pancreatic β cells.\",\n      \"evidence\": \"Co-IP (CNOT8-MSI2), RNA-IP (MSI2-Prdx4 mRNA), western blotting (preprint)\",\n      \"pmids\": [\"bio_10.1101_2024.06.26.599433\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP without reciprocal validation; functional consequence of the CNOT8-MSI2 interaction not directly tested for CNOT8\", \"Preprint, not peer-reviewed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended CNOT8 deadenylase function to mammalian body plan formation, showing its loss elongates poly(A) tails and redirects mesoderm toward ectopic notochord fate.\",\n      \"evidence\": \"CRISPR screen, single-cell transcriptomics, poly(A) tail profiling in gastruloids (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.07.22.666114\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct target transcripts driving the fate shift not pinpointed\", \"Preprint, not peer-reviewed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CNOT8 versus CNOT7 substrate selectivity is encoded, and how its diverse partners (TOB/BTG, PRMT1, MSI2) direct it to distinct transcript pools across cell types, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No transcriptome-wide map distinguishing CNOT8- from CNOT7-specific targets\", \"No structure of CNOT8 engaging a poly(A) substrate within CCR4-NOT\", \"Mechanistic link between deadenylation and the DDR phenotype undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [3, 4, 10]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [4, 10]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [4, 10]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [10, 12]}\n    ],\n    \"complexes\": [\"CCR4-NOT\"],\n    \"partners\": [\"CNOT1\", \"CNOT7\", \"TOB1\", \"BTG2\", \"PABPC1\", \"PRMT1\", \"MSI2\", \"CCR4\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}