{"gene":"RCC2","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":2003,"finding":"TD-60 (RCC2) was purified and cloned as a member of the RCC1 family; it binds preferentially to the nucleotide-free form of small GTPase Rac1. siRNA depletion of TD-60 suppresses overall spindle assembly, blocks cells in prometaphase, activates the spindle assembly checkpoint, and prevents recruitment of passenger proteins survivin and Aurora B to centromeres.","method":"Protein purification, cloning, co-precipitation with nucleotide-free Rac1, siRNA knockdown with immunofluorescence and cell cycle analysis","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal biochemical binding assay, siRNA with multiple orthogonal phenotypic readouts, foundational paper replicated by subsequent studies","pmids":["12919680"],"is_preprint":false},{"year":1998,"finding":"TD-60 (RCC2) and INCENP colocalize identically throughout G2 and mitosis, both concentrating at centromeres in prophase and redistributing to the spindle midzone and cortex during anaphase/cytokinesis, suggesting they cooperate in signaling cytokinesis as chromosome passenger proteins.","method":"Confocal immunofluorescence microscopy, pixel count colocalization analysis, dihydrocytochalasin B treatment","journal":"Chromosoma","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct localization experiment with functional context (cytokinesis signaling), single lab, colocalization without biochemical interaction demonstrated","pmids":["9914378"],"is_preprint":false},{"year":2008,"finding":"Aurora-B activation in vitro requires two cofactors: TD-60 (RCC2) and microtubules. TD-60 is critical for localizing both the chromosome passenger complex (CPC) and Haspin kinase activity to centromeres. Additionally, Aurora-B substrate phosphorylation by centromeric kinases Plk1 and Haspin relieves substrate-mediated inhibition of Aurora-B activation.","method":"In vitro Aurora-B kinase activation assay, siRNA depletion, immunofluorescence localization of CPC components and Haspin","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution assay directly demonstrating cofactor requirement, combined with cellular localization experiments, published in high-impact journal","pmids":["18218899"],"is_preprint":false},{"year":2013,"finding":"TD-60 (RCC2) is an essential regulator of interphase cell cycle progression; siRNA suppression blocks G1/S phase progression and G2-to-mitosis transition in both non-transformed and p53-null cells. TD-60 associates with Rac1 and Arf6 in interphase.","method":"siRNA knockdown, cell cycle analysis (flow cytometry), co-immunoprecipitation with Rac1 and Arf6","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA with cell cycle phenotype confirmed in multiple cell types, co-IP for binding partners, single lab","pmids":["23388455"],"is_preprint":false},{"year":2014,"finding":"RCC2 guides mesenchymal migration by binding to the switch regions of Rac1 and competitively inhibiting GEF action, thereby preventing off-axial protrusion. RCC2 interacts with coronin-1C (Coro1C) and Rac1 in a trimeric complex; Coro1C mediates release of inactive Rac1 from non-protrusive membranes for redistribution to the leading edge. Morpholino knockdown of RCC2 in zebrafish delays arrival of neural crest derivatives at correct locations in vivo.","method":"RNA interference, Co-immunoprecipitation, 1D/3D migration assays, zebrafish morpholino knockdown","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP defining trimeric complex, RNAi with defined polarity/migration phenotype, in vivo validation in zebrafish, multiple orthogonal methods","pmids":["25074804"],"is_preprint":false},{"year":2015,"finding":"TD-60/RCC2 exhibits guanine exchange factor (GEF) activity for the small GTPase RalA, both in vitro and in cells. TD-60 or RalA depletion causes spindle abnormalities and abnormal centromeric accumulation of CPC components in prometaphase. Expression of GTP-locked RalA(Q72L) reverts several mitotic phenotypes caused by TD-60 depletion, placing RalA downstream of TD-60 in CPC regulation.","method":"In vitro GEF activity assay, siRNA depletion, epistasis rescue with GTP-locked RalA mutant, immunofluorescence","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro GEF assay establishing enzymatic activity, genetic epistasis rescue experiment, multiple orthogonal methods in one study","pmids":["26158537"],"is_preprint":false},{"year":2017,"finding":"p53 is a transcriptional regulator of RCC2, acting through a palindromic binding motif in the RCC2 promoter. RCC2 physically interacts with Rac1 via a unique β-hairpin in its RCC1-like domain (identified by crystal structure). p53 or RCC2 deficiency leads to Rac1 activation and impaired haptotaxis; ectopic RCC2 restores directional migration in p53-null cells, defining a p53/RCC2/Rac1 axis.","method":"Chromatin immunoprecipitation (ChIP), crystal structure determination, co-immunoprecipitation, site-directed mutagenesis of RCC2 β-hairpin, haptotaxis assay, overexpression rescue","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with functional mutagenesis, ChIP establishing transcriptional regulation, epistasis rescue experiment, multiple orthogonal methods","pmids":["28869598"],"is_preprint":false},{"year":2017,"finding":"RCC2 overexpression in lung adenocarcinoma cells promotes cell migration, invasion, and EMT, and activates JNK signaling. JNK inhibition suppresses the RCC2-mediated effects on migration, invasion, EMT, and MMP-2/MMP-9 expression, placing RCC2 upstream of MAPK-JNK in this context.","method":"Forced overexpression, siRNA knockdown, in vivo mouse model, pharmacological JNK inhibition, Western blotting for EMT markers and MMPs","journal":"Clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD/OE with defined cellular and in vivo phenotype, pathway placement via pharmacological inhibitor, single lab","pmids":["28606921"],"is_preprint":false},{"year":2018,"finding":"RCC2 regulates apoptosis by blocking Rac1 signaling; forced RCC2 expression blocks spontaneous or staurosporine-induced apoptosis, while RCC2 knockdown increases apoptosis. The protective activity of RCC2 is revoked by constitutively active Rac1(Q61L), confirming that RCC2 acts through Rac1 inhibition.","method":"Overexpression and siRNA knockdown in cancer cell lines, apoptosis assays, epistasis with constitutively active Rac1 mutant","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with Rac1 mutant, KD/OE with defined apoptosis phenotype, single lab","pmids":["29321004"],"is_preprint":false},{"year":2019,"finding":"RCC2 interacts with RalA and promotes downstream RalBP1 activity. RCC2 knockdown decreases RalA-GTP levels and increases MAPK/JNK phosphorylation in gastric cancer cells. RalA knockdown reverses the effects of RCC2 overexpression on cell proliferation, apoptosis, and migration, while RalA overexpression alleviates the effects of RCC2 knockdown, confirming RalA is downstream of RCC2 in these processes.","method":"Co-immunoprecipitation, GTP-RalA pulldown assay, siRNA knockdown, epistasis rescue with RalA overexpression/knockdown, RBC8 pharmacological inhibitor","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus genetic epistasis rescue, active GTPase pulldown, single lab","pmids":["30768358"],"is_preprint":false},{"year":2019,"finding":"RCC2 promotes glioblastoma proliferation and radioresistance via p-STAT3-dependent transcriptional activation of DNMT1. shRNA inhibition of RCC2 reduced tumor proliferation and tumorigenicity in vitro and in vivo, and pharmacological inhibition of DNMT1 attenuated tumor growth.","method":"shRNA knockdown, in vivo tumor models, DNMT1 inhibitor treatment, pathway analysis implicating JAK-STAT signaling","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — KD with tumor phenotype and pharmacological epistasis but mechanistic link to STAT3/DNMT1 not directly demonstrated by direct binding or ChIP","pmids":["31277942"],"is_preprint":false},{"year":2020,"finding":"RCC2 upregulates and stabilizes Sox2 expression by inhibiting ubiquitination-mediated proteasome degradation, and increases Sox2 transcriptional activity and promoter binding. Conditional RCC2 knockout in mice reduces esophageal tumor formation and PCNA expression.","method":"Overexpression/knockdown, ubiquitination assay, Sox2 promoter-binding assay, conditional knockout mouse model, immunohistochemistry","journal":"Molecular cancer research : MCR","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ubiquitination assay with promoter binding experiment, in vivo knockout validation, single lab, multiple orthogonal methods","pmids":["32801160"],"is_preprint":false},{"year":2020,"finding":"RCC2 mediates cisplatin resistance and metastatic behavior in hepatocellular carcinoma via regulation of AKT and Bcl2 survival pathways; RCC2 silencing inhibits proliferation, migration, invasion, and increases apoptosis upon cisplatin treatment.","method":"Lentivirus-based shRNA, cell proliferation/migration/invasion assays, apoptosis assay, Western blotting for AKT and Bcl2","journal":"Human cell","confidence":"Low","confidence_rationale":"Tier 3 / Weak — KD with phenotype and pathway marker measurement, single lab, no direct binding to AKT/Bcl2 demonstrated","pmids":["32239438"],"is_preprint":false},{"year":2020,"finding":"RCC2 interacts with RalA in gastric cancer cells; RCC2 knockdown decreases RalA-GTP and alters MAPK/JNK phosphorylation, while the effects are confirmed by use of RBC8 (a Ral GTPase inhibitor). RCC2 knockdown inhibits tumor progression in vivo.","method":"Co-immunoprecipitation, GTP-RalA pulldown, RBC8 inhibitor, in vivo tumor model, siRNA knockdown","journal":"OncoTargets and therapy","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP plus GTPase activity assay and pharmacological validation, single lab, replicated findings from prior RalA work","pmids":["32341655"],"is_preprint":false},{"year":2021,"finding":"BRD4 drives RCC2 transcription through a BRD4-TP73 complex that binds the RCC2 promoter. Inhibition of BRD4 (genetic or pharmacological) decreases RCC2 expression and ESCC cell proliferation in vitro and in PDX models.","method":"Proteomic/transcriptomic analysis, ChIP or promoter binding assay, BRD4 inhibitors, PDX tumor model","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — transcriptomic plus proteomic identification, promoter-binding mechanistic assay, in vivo PDX validation, single lab","pmids":["34750516"],"is_preprint":false},{"year":2022,"finding":"The m6A reader IGF2BP3 interacts with RCC2 mRNA and stabilizes m6A-modified RCC2 RNA, thereby maintaining RCC2 protein expression in AML cells. IGF2BP3 knockdown reduces RCC2 levels and impairs leukemic cell survival.","method":"RNA immunoprecipitation (RIP), knockdown of IGF2BP3 with Western blot for RCC2, in vitro and in vivo leukemia assays","journal":"Experimental & molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RIP demonstrating direct RNA binding, KD with defined phenotype, single lab","pmids":["35217832"],"is_preprint":false},{"year":2022,"finding":"RCC2 regulates G2/M progression via CDC2 phosphorylation at Tyrosine 15 in glioma cells. Additionally, RCC2 stabilizes the transcription factor BACH1 at its C-terminus, leading to transcriptional upregulation of hexokinase 2 (HK2) and promotion of glycolysis and pentose phosphate pathway activity, defining a PTEN/RCC2/BACH1/HK2 signaling axis.","method":"Gene silencing, RNA-sequencing, metabolomics, Western blotting for CDC2-pY15, co-immunoprecipitation/stabilization of BACH1","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNA-seq with metabolomics and direct protein stabilization assay, multiple orthogonal approaches, single lab","pmids":["36116740"],"is_preprint":false},{"year":2012,"finding":"RCC2/TD60 physically interacts with cortactin in mitotic cells, identified by SILAC-based mass spectrometry and confirmed by reciprocal co-immunoprecipitation. Both proteins colocalize in the equatorial plane of dividing HeLa cells.","method":"SILAC mass spectrometry pulldown, reciprocal co-immunoprecipitation, immunofluorescence colocalization","journal":"Journal of proteomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP confirming MS-identified interaction, immunofluorescence colocalization, single lab","pmids":["22282019"],"is_preprint":false},{"year":2024,"finding":"NudCL2, a co-chaperone of Hsp90, localizes to the midbody and stabilizes RCC2 protein at the midbody in a complex with Hsp90. NudCL2 knockout reduces RCC2 levels; Hsp90 inhibition destabilizes RCC2. RCC2 depletion mirrors NudCL2 KO phenotypes (cytokinesis failure, multinucleation, midbody disorganization). Ectopic RCC2 rescues cytokinesis defects in NudCL2-depleted cells, placing RCC2 downstream of NudCL2/Hsp90 in the cytokinesis pathway.","method":"NudCL2 knockout, iTRAQ-based quantitative proteomics, co-immunoprecipitation, rescue experiment with ectopic RCC2 expression, immunofluorescence","journal":"Protein & cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — quantitative proteomics plus Co-IP defining complex, genetic rescue epistasis, multiple orthogonal methods defining pathway order, single lab but rigorous","pmids":["38801297"],"is_preprint":false},{"year":2025,"finding":"RCC2 undergoes lactylation at lysine K124, mediated by the acyltransferase KAT2A. This lactylation event assists RCC2 in recruiting free SERBP1, thereby stabilizing MAD2L1 mRNA and activating the MAD2L1 signaling pathway to promote breast cancer cell proliferation under high-glucose conditions.","method":"Post-translational modification mapping (K124 lactylation site), KAT2A identification as writer enzyme, co-immunoprecipitation with SERBP1, mRNA stability assay, small molecule inhibitor blocking RCC2 active pocket","journal":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct PTM site identification with writer enzyme, Co-IP defining recruitment of SERBP1, mRNA stability readout, single lab","pmids":["40145796"],"is_preprint":false},{"year":2025,"finding":"ROS accumulation induced by GPx4 inhibition activates Aurora A phosphorylation, which leads to RCC2 ubiquitination and degradation; the Thr418 phosphorylation site on RCC2 is crucial for its ubiquitination at K377. CD24 also targets RCC2 for degradation. RCC2 controls cell migration by promoting ubiquitination and degradation of vimentin, affecting cytoskeletal dynamics. CD24 knockdown inhibits β-catenin signaling by preventing RCC2 degradation (which otherwise suppresses AXIN2 and APC).","method":"Proteomic analysis, site-directed mutagenesis (Thr418, K377), ubiquitination assay, co-immunoprecipitation, ROS quantification, in vitro and in vivo metastasis assays","journal":"Redox biology / The Journal of clinical investigation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ubiquitination site mutagenesis, phosphorylation-ubiquitination cascade established with multiple PTM sites, in vivo validation, two independent papers converging on RCC2 ubiquitination","pmids":["39908861","41090358"],"is_preprint":false},{"year":2022,"finding":"RCC2 binds to HMGA2 by co-immunoprecipitation in colorectal cancer cells, and ectopic RCC2 expression promotes proliferation, migration, and invasion while HMGA2 knockdown has opposite effects, suggesting cooperation.","method":"Co-immunoprecipitation, ectopic overexpression, siRNA knockdown, cell proliferation/invasion assays","journal":"Experimental and therapeutic medicine","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP without functional rescue connecting the interaction to a specific mechanism, single lab","pmids":["36340602"],"is_preprint":false}],"current_model":"RCC2 (TD-60) is a RCC1-family protein that functions as a guanine nucleotide exchange factor (GEF) for both RalA and (weakly) Rac1, acting as a chromosome passenger protein essential for centromeric Aurora-B activation, spindle assembly, kinetochore–microtubule attachment, cytokinesis (stabilized at the midbody by the NudCL2/Hsp90 complex), and interphase cell cycle progression; in migrating cells it competitively inhibits GEF access to Rac1 switch regions to polarize protrusions, while during mitosis it recruits Haspin kinase and CPC components to centromeres and couples RalA–GTP status to CPC regulation. Post-translational regulation includes KAT2A-mediated lactylation at K124 (promoting MAD2L1 mRNA stabilization via SERBP1), Aurora A–dependent phosphorylation at Thr418 triggering K377 ubiquitination and degradation, and transcriptional control by the p53 and BRD4–TP73 pathways."},"narrative":{"mechanistic_narrative":"RCC2 (TD-60) is an RCC1-family protein that operates both as a mitotic chromosome passenger protein and as a guanine nucleotide exchange factor that gates small-GTPase signaling during cell division and migration [PMID:12919680, PMID:26158537]. In mitosis it colocalizes with INCENP at centromeres and the spindle midzone [PMID:9914378] and is required for spindle assembly: its depletion arrests cells in prometaphase, triggers the spindle assembly checkpoint, and abolishes centromeric recruitment of the chromosome passenger complex (survivin, Aurora B) [PMID:12919680]. RCC2 acts as a direct cofactor for Aurora-B activation in vitro and localizes both the CPC and Haspin kinase activity to centromeres [PMID:18218899]. A central biochemical activity is GEF activity toward RalA, which lies downstream of RCC2 in CPC regulation, since GTP-locked RalA reverts the mitotic phenotypes of RCC2 depletion [PMID:26158537]. RCC2 also engages Rac1 through a unique β-hairpin in its RCC1-like domain resolved by crystallography, binding the nucleotide-free form and the GTPase switch regions to competitively block GEF access; this restrains Rac1 to polarize protrusions during mesenchymal migration, acting within a trimeric complex with coronin-1C and downstream of a p53/RCC2/Rac1 axis [PMID:12919680, PMID:25074804, PMID:28869598]. RCC2 is essential for interphase cell cycle progression, with depletion blocking the G1/S and G2/M transitions [PMID:23388455]. During cytokinesis RCC2 is stabilized at the midbody by the NudCL2/Hsp90 chaperone complex, and its loss causes cytokinesis failure and multinucleation [PMID:38801297]. RCC2 is controlled post-translationally by KAT2A-mediated K124 lactylation that promotes SERBP1 recruitment and MAD2L1 mRNA stabilization [PMID:40145796], and by Aurora A-dependent Thr418 phosphorylation that triggers K377 ubiquitination and degradation [PMID:39908861, PMID:41090358]; its transcription is governed by p53 and a BRD4–TP73 complex [PMID:28869598, PMID:34750516]. Across cancers RCC2 acts as an oncogenic effector signaling through RalA and Rac1 to influence proliferation, migration, invasion, EMT, and apoptosis [PMID:28606921, PMID:29321004, PMID:30768358].","teleology":[{"year":1998,"claim":"Established that RCC2/TD-60 behaves as a chromosome passenger protein by tracking its dynamic localization through mitosis alongside a known passenger.","evidence":"Confocal immunofluorescence colocalization with INCENP through G2 and mitosis in cultured cells","pmids":["9914378"],"confidence":"Medium","gaps":["Colocalization only; no biochemical interaction with INCENP demonstrated","Functional role in cytokinesis inferred, not tested by perturbation"]},{"year":2003,"claim":"Identified RCC2 as an RCC1-family protein that binds nucleotide-free Rac1 and is functionally required for spindle assembly and CPC recruitment, defining its core mitotic role.","evidence":"Protein purification/cloning, co-precipitation with nucleotide-free Rac1, and siRNA knockdown with cell-cycle and immunofluorescence readouts","pmids":["12919680"],"confidence":"High","gaps":["Did not establish whether Rac1 binding is mechanistically required for the mitotic phenotype","GEF activity not yet demonstrated"]},{"year":2008,"claim":"Demonstrated that RCC2 is a direct cofactor for Aurora-B kinase activation and is required to localize the CPC and Haspin to centromeres, placing it upstream in centromeric signaling.","evidence":"In vitro Aurora-B activation reconstitution plus siRNA and immunofluorescence localization","pmids":["18218899"],"confidence":"High","gaps":["Molecular mechanism by which RCC2 activates Aurora-B not resolved","Link between RCC2 GTPase activity and Aurora-B activation undefined at this stage"]},{"year":2013,"claim":"Extended RCC2 function beyond mitosis by showing it is required for interphase cell cycle transitions and associates with Rac1 and Arf6.","evidence":"siRNA knockdown with flow-cytometry cell cycle analysis and co-IP in transformed and non-transformed cells","pmids":["23388455"],"confidence":"Medium","gaps":["Arf6 functional relationship not mechanistically dissected","Whether interphase defects are GEF-dependent unknown"]},{"year":2014,"claim":"Defined how RCC2 controls cell migration by binding Rac1 switch regions to block GEF action and partnering with coronin-1C, providing an in vivo migration phenotype.","evidence":"Reciprocal co-IP defining an RCC2–Coro1C–Rac1 complex, migration assays, and zebrafish morpholino knockdown","pmids":["25074804"],"confidence":"High","gaps":["Identity of the GEFs being competed not defined","Coro1C-mediated Rac1 redistribution mechanism partly inferential"]},{"year":2015,"claim":"Resolved the enzymatic identity of RCC2 as a RalA GEF and placed RalA downstream of RCC2 in CPC regulation via epistasis.","evidence":"In vitro GEF assay, siRNA, and rescue with GTP-locked RalA(Q72L)","pmids":["26158537"],"confidence":"High","gaps":["How RalA-GTP feeds into CPC regulation mechanistically not defined","Relationship between RalA-GEF and Rac1-binding activities of the same protein unresolved"]},{"year":2017,"claim":"Integrated transcriptional and structural control by showing p53 transcriptionally regulates RCC2 and that a β-hairpin in the RCC1-like domain mediates Rac1 binding to direct migration.","evidence":"ChIP, crystal structure with site-directed mutagenesis, co-IP, and haptotaxis rescue in p53-null cells","pmids":["28869598"],"confidence":"High","gaps":["Structural basis of RalA GEF activity not captured","How p53 loss couples to Rac1 hyperactivation beyond RCC2 levels not fully resolved"]},{"year":2017,"claim":"Linked RCC2 to oncogenic migration/invasion through JNK signaling in lung adenocarcinoma.","evidence":"Overexpression/knockdown, mouse model, and pharmacological JNK inhibition with EMT/MMP readouts","pmids":["28606921"],"confidence":"Medium","gaps":["Direct molecular connection between RCC2 and JNK activation not shown","GTPase dependence of the JNK effect untested"]},{"year":2018,"claim":"Showed RCC2 suppresses apoptosis specifically through Rac1 inhibition using GTPase epistasis.","evidence":"Overexpression/knockdown apoptosis assays with constitutively active Rac1(Q61L) rescue","pmids":["29321004"],"confidence":"Medium","gaps":["Downstream apoptotic effectors of Rac1 not defined","Single cell-line context"]},{"year":2019,"claim":"Established RCC2–RalA signaling as oncogenic in gastric cancer, with RalA downstream of RCC2 in proliferation, apoptosis, and migration.","evidence":"Co-IP, GTP-RalA pulldown, RBC8 inhibitor, and reciprocal RalA epistasis rescue","pmids":["30768358","32341655"],"confidence":"Medium","gaps":["RalBP1/MAPK-JNK branch only partly mapped","Single tumor type"]},{"year":2022,"claim":"Identified additional mitotic and cancer-relevant physical partners of RCC2 (cortactin, HMGA2) and a glioma G2/M and metabolic axis.","evidence":"SILAC-MS and reciprocal co-IP (cortactin); co-IP (HMGA2); gene silencing with RNA-seq, metabolomics, and BACH1 stabilization assays (glioma)","pmids":["22282019","36340602","36116740"],"confidence":"Medium","gaps":["Functional consequence of the cortactin interaction not established","HMGA2 interaction lacks rescue linking it to a mechanism","BACH1 stabilization mechanism not structurally defined"]},{"year":2022,"claim":"Revealed post-transcriptional control of RCC2 abundance via m6A reader IGF2BP3 in leukemia.","evidence":"RNA immunoprecipitation, IGF2BP3 knockdown with RCC2 Western blot, and leukemia assays","pmids":["35217832"],"confidence":"Medium","gaps":["m6A sites on RCC2 mRNA not mapped","Generalizability beyond AML untested"]},{"year":2024,"claim":"Defined chaperone-mediated stabilization of RCC2 at the midbody, placing RCC2 downstream of NudCL2/Hsp90 in cytokinesis.","evidence":"NudCL2 knockout, iTRAQ proteomics, co-IP, and ectopic RCC2 rescue of cytokinesis defects","pmids":["38801297"],"confidence":"High","gaps":["Whether Hsp90 binds RCC2 directly or via NudCL2 not fully resolved","How midbody stabilization couples to RCC2 GEF activity unknown"]},{"year":2025,"claim":"Established two opposing layers of post-translational control: activating K124 lactylation (KAT2A/SERBP1/MAD2L1) and degradative Thr418 phosphorylation-driven K377 ubiquitination.","evidence":"PTM site mapping, KAT2A/SERBP1 co-IP and mRNA stability assays; Aurora A and CD24-driven ubiquitination with Thr418/K377 mutagenesis and metastasis assays","pmids":["40145796","39908861","41090358"],"confidence":"Medium","gaps":["E3 ligase mediating K377 ubiquitination not identified","Crosstalk between lactylation and ubiquitination not tested","Vimentin-degradation arm needs mechanistic depth"]},{"year":null,"claim":"How RCC2's dual GTPase-regulatory activities (RalA GEF vs Rac1 GEF inhibition) are coordinated within single cells and tied to its mitotic versus migratory functions remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structure capturing simultaneous RalA and Rac1 engagement","Mechanism switching RCC2 between mitotic CPC role and interphase migration role unknown","Whether PTMs (lactylation, phosphorylation) toggle GTPase-target selectivity untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[5,0,4,6]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[4,17]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[1,0]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0,2,3,5,18]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,5,8,9]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[4]}],"complexes":["RCC2–Coronin-1C–Rac1 complex","chromosome passenger complex (CPC) regulator","NudCL2/Hsp90 chaperone complex (client)"],"partners":["RALA","RAC1","ARF6","INCENP","CORO1C","CTTN","SERBP1","NUDCD3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9P258","full_name":"Protein RCC2","aliases":["RCC1-like protein TD-60","Telophase disk protein of 60 kDa"],"length_aa":522,"mass_kda":56.1,"function":"Multifunctional protein that may affect its functions by regulating the activity of small GTPases, such as RAC1 and RALA (PubMed:12919680, PubMed:25074804, PubMed:26158537, PubMed:28869598). Required for normal progress through the cell cycle, both during interphase and during mitosis (PubMed:12919680, PubMed:23388455, PubMed:26158537). Required for the presence of normal levels of MAD2L1, AURKB and BIRC5 on inner centromeres during mitosis, and for normal attachment of kinetochores to mitotic spindles (PubMed:12919680, PubMed:26158537). Required for normal organization of the microtubule cytoskeleton in interphase cells (PubMed:23388455). Functions as guanine nucleotide exchange factor (GEF) for RALA (PubMed:26158537). Interferes with the activation of RAC1 by guanine nucleotide exchange factors (PubMed:25074804). Prevents accumulation of active, GTP-bound RAC1, and suppresses RAC1-mediated reorganization of the actin cytoskeleton and formation of membrane protrusions (PubMed:25074804, PubMed:28869598). Required for normal cellular responses to contacts with the extracellular matrix of adjacent cells, and for directional cell migration in response to a fibronectin gradient (in vitro) (PubMed:25074804, PubMed:28869598)","subcellular_location":"Nucleus, nucleolus; Nucleus; Cytoplasm, cytoskeleton; Chromosome, centromere; Cytoplasm, cytoskeleton, spindle; Chromosome; Midbody; Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9P258/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RCC2","classification":"Not Classified","n_dependent_lines":33,"n_total_lines":1208,"dependency_fraction":0.027317880794701987},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CAPZB","stoichiometry":0.2},{"gene":"VCL","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/RCC2","total_profiled":1310},"omim":[{"mim_id":"609977","title":"CELL DIVISION CYCLE-ASSOCIATED PROTEIN 8; CDCA8","url":"https://www.omim.org/entry/609977"},{"mim_id":"609587","title":"REGULATOR OF CHROMOSOME CONDENSATION 2; RCC2","url":"https://www.omim.org/entry/609587"},{"mim_id":"604970","title":"AURORA KINASE B; AURKB","url":"https://www.omim.org/entry/604970"}],"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/RCC2"},"hgnc":{"alias_symbol":["TD-60"],"prev_symbol":[]},"alphafold":{"accession":"Q9P258","domains":[{"cath_id":"2.130.10.30","chopping":"96-516","consensus_level":"medium","plddt":97.6473,"start":96,"end":516}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9P258","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9P258-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9P258-F1-predicted_aligned_error_v6.png","plddt_mean":88.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RCC2","jax_strain_url":"https://www.jax.org/strain/search?query=RCC2"},"sequence":{"accession":"Q9P258","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9P258.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9P258/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9P258"}},"corpus_meta":[{"pmid":"18218899","id":"PMC_18218899","title":"Centromeric Aurora-B activation requires TD-60, microtubules, and substrate priming phosphorylation.","date":"2008","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/18218899","citation_count":132,"is_preprint":false},{"pmid":"35217832","id":"PMC_35217832","title":"The m6A reader IGF2BP3 promotes acute myeloid leukemia progression by enhancing RCC2 stability.","date":"2022","source":"Experimental & molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35217832","citation_count":113,"is_preprint":false},{"pmid":"12919680","id":"PMC_12919680","title":"The mammalian passenger protein TD-60 is an RCC1 family member with an essential role in prometaphase to metaphase progression.","date":"2003","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/12919680","citation_count":101,"is_preprint":false},{"pmid":"23442884","id":"PMC_23442884","title":"MiR-29c is downregulated in gastric carcinomas and regulates cell proliferation by targeting RCC2.","date":"2013","source":"Molecular 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over-expression in tumor cells alters apoptosis and drug sensitivity by regulating Rac1 activation.","date":"2018","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/29321004","citation_count":34,"is_preprint":false},{"pmid":"34750516","id":"PMC_34750516","title":"BRD4 drives esophageal squamous cell carcinoma growth by promoting RCC2 expression.","date":"2021","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/34750516","citation_count":30,"is_preprint":false},{"pmid":"31839818","id":"PMC_31839818","title":"RCC2 promotes breast cancer progression through regulation of Wnt signaling and inducing EMT.","date":"2019","source":"Journal of Cancer","url":"https://pubmed.ncbi.nlm.nih.gov/31839818","citation_count":30,"is_preprint":false},{"pmid":"31749881","id":"PMC_31749881","title":"MicroRNA-331-3p inhibits proliferation and metastasis of ovarian cancer by targeting RCC2.","date":"2018","source":"Archives of medical science : 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Cancer Institute of Mexico","url":"https://pubmed.ncbi.nlm.nih.gov/36593385","citation_count":20,"is_preprint":false},{"pmid":"32801160","id":"PMC_32801160","title":"RCC2 Promotes Esophageal Cancer Growth by Regulating Activity and Expression of the Sox2 Transcription Factor.","date":"2020","source":"Molecular cancer research : MCR","url":"https://pubmed.ncbi.nlm.nih.gov/32801160","citation_count":19,"is_preprint":false},{"pmid":"32239438","id":"PMC_32239438","title":"RCC2 contributes to tumor invasion and chemoresistance to cisplatin in hepatocellular carcinoma.","date":"2020","source":"Human cell","url":"https://pubmed.ncbi.nlm.nih.gov/32239438","citation_count":18,"is_preprint":false},{"pmid":"22282019","id":"PMC_22282019","title":"Mass spectrometric analysis identifies a cortactin-RCC2/TD60 interaction in mitotic cells.","date":"2012","source":"Journal of proteomics","url":"https://pubmed.ncbi.nlm.nih.gov/22282019","citation_count":18,"is_preprint":false},{"pmid":"30768358","id":"PMC_30768358","title":"RCC2, a regulator of the RalA signaling pathway, is identified as a novel therapeutic target in cisplatin-resistant ovarian cancer.","date":"2019","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/30768358","citation_count":18,"is_preprint":false},{"pmid":"38008751","id":"PMC_38008751","title":"RCC2 promotes prostate cancer cell proliferation and migration through Hh/GLI1 signaling pathway and cancer stem-like cells.","date":"2023","source":"Biology direct","url":"https://pubmed.ncbi.nlm.nih.gov/38008751","citation_count":15,"is_preprint":false},{"pmid":"32803782","id":"PMC_32803782","title":"MicroRNA-191 modulates cisplatin-induced DNA damage response by targeting RCC2.","date":"2020","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/32803782","citation_count":10,"is_preprint":false},{"pmid":"39908861","id":"PMC_39908861","title":"Inhibition of glutathione peroxidase 4 suppresses gastric cancer peritoneal metastasis via regulation of RCC2 homeostasis.","date":"2025","source":"Redox biology","url":"https://pubmed.ncbi.nlm.nih.gov/39908861","citation_count":9,"is_preprint":false},{"pmid":"32341655","id":"PMC_32341655","title":"RCC2 Interacts with Small GTPase RalA and Regulates Cell Proliferation and Motility in Gastric Cancer.","date":"2020","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/32341655","citation_count":9,"is_preprint":false},{"pmid":"32565805","id":"PMC_32565805","title":"RCC2 Expression Stimulates ER-Positive Breast Tumorigenesis.","date":"2020","source":"Journal of 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cell","url":"https://pubmed.ncbi.nlm.nih.gov/38801297","citation_count":3,"is_preprint":false},{"pmid":"39043840","id":"PMC_39043840","title":"circRNA-0015004 act as a ceRNA to promote RCC2 expression in hepatocellular carcinoma.","date":"2024","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/39043840","citation_count":3,"is_preprint":false},{"pmid":"38555043","id":"PMC_38555043","title":"Promotive actions of lncRNA EBLN3P involved in cervical cancer progression via interacting with miR-29c-3p and TAF15 to modify RCC2.","date":"2024","source":"Archives of biochemistry and biophysics","url":"https://pubmed.ncbi.nlm.nih.gov/38555043","citation_count":3,"is_preprint":false},{"pmid":"36340602","id":"PMC_36340602","title":"A pan‑cancer analysis of RCC2 and its interaction with HMGA2 protein in an in vitro model of colorectal cancer cells.","date":"2022","source":"Experimental and therapeutic 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dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/40129067","citation_count":0,"is_preprint":false},{"pmid":"42000636","id":"PMC_42000636","title":"Decoupling lactylation-associated metabolic remodelling in Asthma: Integrated multi-omics and machine learning identify RCC2 as a potential therapeutic target.","date":"2026","source":"Computer methods and programs in biomedicine","url":"https://pubmed.ncbi.nlm.nih.gov/42000636","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":21422,"output_tokens":5723,"usd":0.075055,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14369,"output_tokens":4700,"usd":0.094673,"stage2_stop_reason":"end_turn"},"total_usd":0.169728,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"TD-60 (RCC2) was purified and cloned as a member of the RCC1 family; it binds preferentially to the nucleotide-free form of small GTPase Rac1. siRNA depletion of TD-60 suppresses overall spindle assembly, blocks cells in prometaphase, activates the spindle assembly checkpoint, and prevents recruitment of passenger proteins survivin and Aurora B to centromeres.\",\n      \"method\": \"Protein purification, cloning, co-precipitation with nucleotide-free Rac1, siRNA knockdown with immunofluorescence and cell cycle analysis\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal biochemical binding assay, siRNA with multiple orthogonal phenotypic readouts, foundational paper replicated by subsequent studies\",\n      \"pmids\": [\"12919680\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"TD-60 (RCC2) and INCENP colocalize identically throughout G2 and mitosis, both concentrating at centromeres in prophase and redistributing to the spindle midzone and cortex during anaphase/cytokinesis, suggesting they cooperate in signaling cytokinesis as chromosome passenger proteins.\",\n      \"method\": \"Confocal immunofluorescence microscopy, pixel count colocalization analysis, dihydrocytochalasin B treatment\",\n      \"journal\": \"Chromosoma\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct localization experiment with functional context (cytokinesis signaling), single lab, colocalization without biochemical interaction demonstrated\",\n      \"pmids\": [\"9914378\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Aurora-B activation in vitro requires two cofactors: TD-60 (RCC2) and microtubules. TD-60 is critical for localizing both the chromosome passenger complex (CPC) and Haspin kinase activity to centromeres. Additionally, Aurora-B substrate phosphorylation by centromeric kinases Plk1 and Haspin relieves substrate-mediated inhibition of Aurora-B activation.\",\n      \"method\": \"In vitro Aurora-B kinase activation assay, siRNA depletion, immunofluorescence localization of CPC components and Haspin\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution assay directly demonstrating cofactor requirement, combined with cellular localization experiments, published in high-impact journal\",\n      \"pmids\": [\"18218899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TD-60 (RCC2) is an essential regulator of interphase cell cycle progression; siRNA suppression blocks G1/S phase progression and G2-to-mitosis transition in both non-transformed and p53-null cells. TD-60 associates with Rac1 and Arf6 in interphase.\",\n      \"method\": \"siRNA knockdown, cell cycle analysis (flow cytometry), co-immunoprecipitation with Rac1 and Arf6\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA with cell cycle phenotype confirmed in multiple cell types, co-IP for binding partners, single lab\",\n      \"pmids\": [\"23388455\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"RCC2 guides mesenchymal migration by binding to the switch regions of Rac1 and competitively inhibiting GEF action, thereby preventing off-axial protrusion. RCC2 interacts with coronin-1C (Coro1C) and Rac1 in a trimeric complex; Coro1C mediates release of inactive Rac1 from non-protrusive membranes for redistribution to the leading edge. Morpholino knockdown of RCC2 in zebrafish delays arrival of neural crest derivatives at correct locations in vivo.\",\n      \"method\": \"RNA interference, Co-immunoprecipitation, 1D/3D migration assays, zebrafish morpholino knockdown\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP defining trimeric complex, RNAi with defined polarity/migration phenotype, in vivo validation in zebrafish, multiple orthogonal methods\",\n      \"pmids\": [\"25074804\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TD-60/RCC2 exhibits guanine exchange factor (GEF) activity for the small GTPase RalA, both in vitro and in cells. TD-60 or RalA depletion causes spindle abnormalities and abnormal centromeric accumulation of CPC components in prometaphase. Expression of GTP-locked RalA(Q72L) reverts several mitotic phenotypes caused by TD-60 depletion, placing RalA downstream of TD-60 in CPC regulation.\",\n      \"method\": \"In vitro GEF activity assay, siRNA depletion, epistasis rescue with GTP-locked RalA mutant, immunofluorescence\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro GEF assay establishing enzymatic activity, genetic epistasis rescue experiment, multiple orthogonal methods in one study\",\n      \"pmids\": [\"26158537\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"p53 is a transcriptional regulator of RCC2, acting through a palindromic binding motif in the RCC2 promoter. RCC2 physically interacts with Rac1 via a unique β-hairpin in its RCC1-like domain (identified by crystal structure). p53 or RCC2 deficiency leads to Rac1 activation and impaired haptotaxis; ectopic RCC2 restores directional migration in p53-null cells, defining a p53/RCC2/Rac1 axis.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP), crystal structure determination, co-immunoprecipitation, site-directed mutagenesis of RCC2 β-hairpin, haptotaxis assay, overexpression rescue\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with functional mutagenesis, ChIP establishing transcriptional regulation, epistasis rescue experiment, multiple orthogonal methods\",\n      \"pmids\": [\"28869598\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"RCC2 overexpression in lung adenocarcinoma cells promotes cell migration, invasion, and EMT, and activates JNK signaling. JNK inhibition suppresses the RCC2-mediated effects on migration, invasion, EMT, and MMP-2/MMP-9 expression, placing RCC2 upstream of MAPK-JNK in this context.\",\n      \"method\": \"Forced overexpression, siRNA knockdown, in vivo mouse model, pharmacological JNK inhibition, Western blotting for EMT markers and MMPs\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD/OE with defined cellular and in vivo phenotype, pathway placement via pharmacological inhibitor, single lab\",\n      \"pmids\": [\"28606921\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"RCC2 regulates apoptosis by blocking Rac1 signaling; forced RCC2 expression blocks spontaneous or staurosporine-induced apoptosis, while RCC2 knockdown increases apoptosis. The protective activity of RCC2 is revoked by constitutively active Rac1(Q61L), confirming that RCC2 acts through Rac1 inhibition.\",\n      \"method\": \"Overexpression and siRNA knockdown in cancer cell lines, apoptosis assays, epistasis with constitutively active Rac1 mutant\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with Rac1 mutant, KD/OE with defined apoptosis phenotype, single lab\",\n      \"pmids\": [\"29321004\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"RCC2 interacts with RalA and promotes downstream RalBP1 activity. RCC2 knockdown decreases RalA-GTP levels and increases MAPK/JNK phosphorylation in gastric cancer cells. RalA knockdown reverses the effects of RCC2 overexpression on cell proliferation, apoptosis, and migration, while RalA overexpression alleviates the effects of RCC2 knockdown, confirming RalA is downstream of RCC2 in these processes.\",\n      \"method\": \"Co-immunoprecipitation, GTP-RalA pulldown assay, siRNA knockdown, epistasis rescue with RalA overexpression/knockdown, RBC8 pharmacological inhibitor\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus genetic epistasis rescue, active GTPase pulldown, single lab\",\n      \"pmids\": [\"30768358\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"RCC2 promotes glioblastoma proliferation and radioresistance via p-STAT3-dependent transcriptional activation of DNMT1. shRNA inhibition of RCC2 reduced tumor proliferation and tumorigenicity in vitro and in vivo, and pharmacological inhibition of DNMT1 attenuated tumor growth.\",\n      \"method\": \"shRNA knockdown, in vivo tumor models, DNMT1 inhibitor treatment, pathway analysis implicating JAK-STAT signaling\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — KD with tumor phenotype and pharmacological epistasis but mechanistic link to STAT3/DNMT1 not directly demonstrated by direct binding or ChIP\",\n      \"pmids\": [\"31277942\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RCC2 upregulates and stabilizes Sox2 expression by inhibiting ubiquitination-mediated proteasome degradation, and increases Sox2 transcriptional activity and promoter binding. Conditional RCC2 knockout in mice reduces esophageal tumor formation and PCNA expression.\",\n      \"method\": \"Overexpression/knockdown, ubiquitination assay, Sox2 promoter-binding assay, conditional knockout mouse model, immunohistochemistry\",\n      \"journal\": \"Molecular cancer research : MCR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ubiquitination assay with promoter binding experiment, in vivo knockout validation, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"32801160\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RCC2 mediates cisplatin resistance and metastatic behavior in hepatocellular carcinoma via regulation of AKT and Bcl2 survival pathways; RCC2 silencing inhibits proliferation, migration, invasion, and increases apoptosis upon cisplatin treatment.\",\n      \"method\": \"Lentivirus-based shRNA, cell proliferation/migration/invasion assays, apoptosis assay, Western blotting for AKT and Bcl2\",\n      \"journal\": \"Human cell\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — KD with phenotype and pathway marker measurement, single lab, no direct binding to AKT/Bcl2 demonstrated\",\n      \"pmids\": [\"32239438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RCC2 interacts with RalA in gastric cancer cells; RCC2 knockdown decreases RalA-GTP and alters MAPK/JNK phosphorylation, while the effects are confirmed by use of RBC8 (a Ral GTPase inhibitor). RCC2 knockdown inhibits tumor progression in vivo.\",\n      \"method\": \"Co-immunoprecipitation, GTP-RalA pulldown, RBC8 inhibitor, in vivo tumor model, siRNA knockdown\",\n      \"journal\": \"OncoTargets and therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP plus GTPase activity assay and pharmacological validation, single lab, replicated findings from prior RalA work\",\n      \"pmids\": [\"32341655\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"BRD4 drives RCC2 transcription through a BRD4-TP73 complex that binds the RCC2 promoter. Inhibition of BRD4 (genetic or pharmacological) decreases RCC2 expression and ESCC cell proliferation in vitro and in PDX models.\",\n      \"method\": \"Proteomic/transcriptomic analysis, ChIP or promoter binding assay, BRD4 inhibitors, PDX tumor model\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — transcriptomic plus proteomic identification, promoter-binding mechanistic assay, in vivo PDX validation, single lab\",\n      \"pmids\": [\"34750516\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The m6A reader IGF2BP3 interacts with RCC2 mRNA and stabilizes m6A-modified RCC2 RNA, thereby maintaining RCC2 protein expression in AML cells. IGF2BP3 knockdown reduces RCC2 levels and impairs leukemic cell survival.\",\n      \"method\": \"RNA immunoprecipitation (RIP), knockdown of IGF2BP3 with Western blot for RCC2, in vitro and in vivo leukemia assays\",\n      \"journal\": \"Experimental & molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RIP demonstrating direct RNA binding, KD with defined phenotype, single lab\",\n      \"pmids\": [\"35217832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RCC2 regulates G2/M progression via CDC2 phosphorylation at Tyrosine 15 in glioma cells. Additionally, RCC2 stabilizes the transcription factor BACH1 at its C-terminus, leading to transcriptional upregulation of hexokinase 2 (HK2) and promotion of glycolysis and pentose phosphate pathway activity, defining a PTEN/RCC2/BACH1/HK2 signaling axis.\",\n      \"method\": \"Gene silencing, RNA-sequencing, metabolomics, Western blotting for CDC2-pY15, co-immunoprecipitation/stabilization of BACH1\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNA-seq with metabolomics and direct protein stabilization assay, multiple orthogonal approaches, single lab\",\n      \"pmids\": [\"36116740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"RCC2/TD60 physically interacts with cortactin in mitotic cells, identified by SILAC-based mass spectrometry and confirmed by reciprocal co-immunoprecipitation. Both proteins colocalize in the equatorial plane of dividing HeLa cells.\",\n      \"method\": \"SILAC mass spectrometry pulldown, reciprocal co-immunoprecipitation, immunofluorescence colocalization\",\n      \"journal\": \"Journal of proteomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP confirming MS-identified interaction, immunofluorescence colocalization, single lab\",\n      \"pmids\": [\"22282019\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"NudCL2, a co-chaperone of Hsp90, localizes to the midbody and stabilizes RCC2 protein at the midbody in a complex with Hsp90. NudCL2 knockout reduces RCC2 levels; Hsp90 inhibition destabilizes RCC2. RCC2 depletion mirrors NudCL2 KO phenotypes (cytokinesis failure, multinucleation, midbody disorganization). Ectopic RCC2 rescues cytokinesis defects in NudCL2-depleted cells, placing RCC2 downstream of NudCL2/Hsp90 in the cytokinesis pathway.\",\n      \"method\": \"NudCL2 knockout, iTRAQ-based quantitative proteomics, co-immunoprecipitation, rescue experiment with ectopic RCC2 expression, immunofluorescence\",\n      \"journal\": \"Protein & cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — quantitative proteomics plus Co-IP defining complex, genetic rescue epistasis, multiple orthogonal methods defining pathway order, single lab but rigorous\",\n      \"pmids\": [\"38801297\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"RCC2 undergoes lactylation at lysine K124, mediated by the acyltransferase KAT2A. This lactylation event assists RCC2 in recruiting free SERBP1, thereby stabilizing MAD2L1 mRNA and activating the MAD2L1 signaling pathway to promote breast cancer cell proliferation under high-glucose conditions.\",\n      \"method\": \"Post-translational modification mapping (K124 lactylation site), KAT2A identification as writer enzyme, co-immunoprecipitation with SERBP1, mRNA stability assay, small molecule inhibitor blocking RCC2 active pocket\",\n      \"journal\": \"Advanced science (Weinheim, Baden-Wurttemberg, Germany)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct PTM site identification with writer enzyme, Co-IP defining recruitment of SERBP1, mRNA stability readout, single lab\",\n      \"pmids\": [\"40145796\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ROS accumulation induced by GPx4 inhibition activates Aurora A phosphorylation, which leads to RCC2 ubiquitination and degradation; the Thr418 phosphorylation site on RCC2 is crucial for its ubiquitination at K377. CD24 also targets RCC2 for degradation. RCC2 controls cell migration by promoting ubiquitination and degradation of vimentin, affecting cytoskeletal dynamics. CD24 knockdown inhibits β-catenin signaling by preventing RCC2 degradation (which otherwise suppresses AXIN2 and APC).\",\n      \"method\": \"Proteomic analysis, site-directed mutagenesis (Thr418, K377), ubiquitination assay, co-immunoprecipitation, ROS quantification, in vitro and in vivo metastasis assays\",\n      \"journal\": \"Redox biology / The Journal of clinical investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ubiquitination site mutagenesis, phosphorylation-ubiquitination cascade established with multiple PTM sites, in vivo validation, two independent papers converging on RCC2 ubiquitination\",\n      \"pmids\": [\"39908861\", \"41090358\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RCC2 binds to HMGA2 by co-immunoprecipitation in colorectal cancer cells, and ectopic RCC2 expression promotes proliferation, migration, and invasion while HMGA2 knockdown has opposite effects, suggesting cooperation.\",\n      \"method\": \"Co-immunoprecipitation, ectopic overexpression, siRNA knockdown, cell proliferation/invasion assays\",\n      \"journal\": \"Experimental and therapeutic medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP without functional rescue connecting the interaction to a specific mechanism, single lab\",\n      \"pmids\": [\"36340602\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RCC2 (TD-60) is a RCC1-family protein that functions as a guanine nucleotide exchange factor (GEF) for both RalA and (weakly) Rac1, acting as a chromosome passenger protein essential for centromeric Aurora-B activation, spindle assembly, kinetochore–microtubule attachment, cytokinesis (stabilized at the midbody by the NudCL2/Hsp90 complex), and interphase cell cycle progression; in migrating cells it competitively inhibits GEF access to Rac1 switch regions to polarize protrusions, while during mitosis it recruits Haspin kinase and CPC components to centromeres and couples RalA–GTP status to CPC regulation. Post-translational regulation includes KAT2A-mediated lactylation at K124 (promoting MAD2L1 mRNA stabilization via SERBP1), Aurora A–dependent phosphorylation at Thr418 triggering K377 ubiquitination and degradation, and transcriptional control by the p53 and BRD4–TP73 pathways.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RCC2 (TD-60) is an RCC1-family protein that operates both as a mitotic chromosome passenger protein and as a guanine nucleotide exchange factor that gates small-GTPase signaling during cell division and migration [#0, #5]. In mitosis it colocalizes with INCENP at centromeres and the spindle midzone [#1] and is required for spindle assembly: its depletion arrests cells in prometaphase, triggers the spindle assembly checkpoint, and abolishes centromeric recruitment of the chromosome passenger complex (survivin, Aurora B) [#0]. RCC2 acts as a direct cofactor for Aurora-B activation in vitro and localizes both the CPC and Haspin kinase activity to centromeres [#2]. A central biochemical activity is GEF activity toward RalA, which lies downstream of RCC2 in CPC regulation, since GTP-locked RalA reverts the mitotic phenotypes of RCC2 depletion [#5]. RCC2 also engages Rac1 through a unique β-hairpin in its RCC1-like domain resolved by crystallography, binding the nucleotide-free form and the GTPase switch regions to competitively block GEF access; this restrains Rac1 to polarize protrusions during mesenchymal migration, acting within a trimeric complex with coronin-1C and downstream of a p53/RCC2/Rac1 axis [#0, #4, #6]. RCC2 is essential for interphase cell cycle progression, with depletion blocking the G1/S and G2/M transitions [#3]. During cytokinesis RCC2 is stabilized at the midbody by the NudCL2/Hsp90 chaperone complex, and its loss causes cytokinesis failure and multinucleation [#18]. RCC2 is controlled post-translationally by KAT2A-mediated K124 lactylation that promotes SERBP1 recruitment and MAD2L1 mRNA stabilization [#19], and by Aurora A-dependent Thr418 phosphorylation that triggers K377 ubiquitination and degradation [#20]; its transcription is governed by p53 and a BRD4–TP73 complex [#6, #14]. Across cancers RCC2 acts as an oncogenic effector signaling through RalA and Rac1 to influence proliferation, migration, invasion, EMT, and apoptosis [#7, #8, #9].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established that RCC2/TD-60 behaves as a chromosome passenger protein by tracking its dynamic localization through mitosis alongside a known passenger.\",\n      \"evidence\": \"Confocal immunofluorescence colocalization with INCENP through G2 and mitosis in cultured cells\",\n      \"pmids\": [\"9914378\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Colocalization only; no biochemical interaction with INCENP demonstrated\", \"Functional role in cytokinesis inferred, not tested by perturbation\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identified RCC2 as an RCC1-family protein that binds nucleotide-free Rac1 and is functionally required for spindle assembly and CPC recruitment, defining its core mitotic role.\",\n      \"evidence\": \"Protein purification/cloning, co-precipitation with nucleotide-free Rac1, and siRNA knockdown with cell-cycle and immunofluorescence readouts\",\n      \"pmids\": [\"12919680\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish whether Rac1 binding is mechanistically required for the mitotic phenotype\", \"GEF activity not yet demonstrated\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrated that RCC2 is a direct cofactor for Aurora-B kinase activation and is required to localize the CPC and Haspin to centromeres, placing it upstream in centromeric signaling.\",\n      \"evidence\": \"In vitro Aurora-B activation reconstitution plus siRNA and immunofluorescence localization\",\n      \"pmids\": [\"18218899\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which RCC2 activates Aurora-B not resolved\", \"Link between RCC2 GTPase activity and Aurora-B activation undefined at this stage\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Extended RCC2 function beyond mitosis by showing it is required for interphase cell cycle transitions and associates with Rac1 and Arf6.\",\n      \"evidence\": \"siRNA knockdown with flow-cytometry cell cycle analysis and co-IP in transformed and non-transformed cells\",\n      \"pmids\": [\"23388455\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Arf6 functional relationship not mechanistically dissected\", \"Whether interphase defects are GEF-dependent unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined how RCC2 controls cell migration by binding Rac1 switch regions to block GEF action and partnering with coronin-1C, providing an in vivo migration phenotype.\",\n      \"evidence\": \"Reciprocal co-IP defining an RCC2–Coro1C–Rac1 complex, migration assays, and zebrafish morpholino knockdown\",\n      \"pmids\": [\"25074804\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the GEFs being competed not defined\", \"Coro1C-mediated Rac1 redistribution mechanism partly inferential\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Resolved the enzymatic identity of RCC2 as a RalA GEF and placed RalA downstream of RCC2 in CPC regulation via epistasis.\",\n      \"evidence\": \"In vitro GEF assay, siRNA, and rescue with GTP-locked RalA(Q72L)\",\n      \"pmids\": [\"26158537\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How RalA-GTP feeds into CPC regulation mechanistically not defined\", \"Relationship between RalA-GEF and Rac1-binding activities of the same protein unresolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Integrated transcriptional and structural control by showing p53 transcriptionally regulates RCC2 and that a β-hairpin in the RCC1-like domain mediates Rac1 binding to direct migration.\",\n      \"evidence\": \"ChIP, crystal structure with site-directed mutagenesis, co-IP, and haptotaxis rescue in p53-null cells\",\n      \"pmids\": [\"28869598\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of RalA GEF activity not captured\", \"How p53 loss couples to Rac1 hyperactivation beyond RCC2 levels not fully resolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Linked RCC2 to oncogenic migration/invasion through JNK signaling in lung adenocarcinoma.\",\n      \"evidence\": \"Overexpression/knockdown, mouse model, and pharmacological JNK inhibition with EMT/MMP readouts\",\n      \"pmids\": [\"28606921\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular connection between RCC2 and JNK activation not shown\", \"GTPase dependence of the JNK effect untested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed RCC2 suppresses apoptosis specifically through Rac1 inhibition using GTPase epistasis.\",\n      \"evidence\": \"Overexpression/knockdown apoptosis assays with constitutively active Rac1(Q61L) rescue\",\n      \"pmids\": [\"29321004\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream apoptotic effectors of Rac1 not defined\", \"Single cell-line context\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established RCC2–RalA signaling as oncogenic in gastric cancer, with RalA downstream of RCC2 in proliferation, apoptosis, and migration.\",\n      \"evidence\": \"Co-IP, GTP-RalA pulldown, RBC8 inhibitor, and reciprocal RalA epistasis rescue\",\n      \"pmids\": [\"30768358\", \"32341655\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"RalBP1/MAPK-JNK branch only partly mapped\", \"Single tumor type\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identified additional mitotic and cancer-relevant physical partners of RCC2 (cortactin, HMGA2) and a glioma G2/M and metabolic axis.\",\n      \"evidence\": \"SILAC-MS and reciprocal co-IP (cortactin); co-IP (HMGA2); gene silencing with RNA-seq, metabolomics, and BACH1 stabilization assays (glioma)\",\n      \"pmids\": [\"22282019\", \"36340602\", \"36116740\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the cortactin interaction not established\", \"HMGA2 interaction lacks rescue linking it to a mechanism\", \"BACH1 stabilization mechanism not structurally defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Revealed post-transcriptional control of RCC2 abundance via m6A reader IGF2BP3 in leukemia.\",\n      \"evidence\": \"RNA immunoprecipitation, IGF2BP3 knockdown with RCC2 Western blot, and leukemia assays\",\n      \"pmids\": [\"35217832\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"m6A sites on RCC2 mRNA not mapped\", \"Generalizability beyond AML untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined chaperone-mediated stabilization of RCC2 at the midbody, placing RCC2 downstream of NudCL2/Hsp90 in cytokinesis.\",\n      \"evidence\": \"NudCL2 knockout, iTRAQ proteomics, co-IP, and ectopic RCC2 rescue of cytokinesis defects\",\n      \"pmids\": [\"38801297\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Hsp90 binds RCC2 directly or via NudCL2 not fully resolved\", \"How midbody stabilization couples to RCC2 GEF activity unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Established two opposing layers of post-translational control: activating K124 lactylation (KAT2A/SERBP1/MAD2L1) and degradative Thr418 phosphorylation-driven K377 ubiquitination.\",\n      \"evidence\": \"PTM site mapping, KAT2A/SERBP1 co-IP and mRNA stability assays; Aurora A and CD24-driven ubiquitination with Thr418/K377 mutagenesis and metastasis assays\",\n      \"pmids\": [\"40145796\", \"39908861\", \"41090358\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"E3 ligase mediating K377 ubiquitination not identified\", \"Crosstalk between lactylation and ubiquitination not tested\", \"Vimentin-degradation arm needs mechanistic depth\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RCC2's dual GTPase-regulatory activities (RalA GEF vs Rac1 GEF inhibition) are coordinated within single cells and tied to its mitotic versus migratory functions remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structure capturing simultaneous RalA and Rac1 engagement\", \"Mechanism switching RCC2 between mitotic CPC role and interphase migration role unknown\", \"Whether PTMs (lactylation, phosphorylation) toggle GTPase-target selectivity untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [5, 0, 4, 6]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [4, 17]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [1, 0]},\n      {\"term_id\": \"GO:0005819\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 2, 3, 5, 18]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 5, 8, 9]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [\n      \"RCC2–Coronin-1C–Rac1 complex\",\n      \"chromosome passenger complex (CPC) regulator\",\n      \"NudCL2/Hsp90 chaperone complex (client)\"\n    ],\n    \"partners\": [\n      \"RALA\",\n      \"RAC1\",\n      \"ARF6\",\n      \"INCENP\",\n      \"CORO1C\",\n      \"CTTN\",\n      \"SERBP1\",\n      \"NUDCD3\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":9,"faith_total":9,"faith_pct":100.0}}