{"gene":"ELL2","run_date":"2026-06-09T23:54:43","timeline":{"discoveries":[{"year":1997,"finding":"ELL2 is a RNA polymerase II elongation factor that stimulates transcriptional elongation, with its elongation activation domain localized to its N-terminal region (homologous to ELL).","method":"In vitro transcription assays, structure-function studies with truncation mutants","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro transcription assay with domain mapping via mutagenesis, single lab but multiple orthogonal methods","pmids":["9108030"],"is_preprint":false},{"year":2009,"finding":"ELL2 (induced in plasma cells) stimulates use of the promoter-proximal poly(A) site and exon skipping in the immunoglobulin heavy-chain pre-mRNA; ELL2 and polyadenylation factor CstF-64 co-track with RNA polymerase II across Igh gene segments, and this co-loading requires ELL2.","method":"siRNA knockdown, chromatin immunoprecipitation (ChIP), reporter constructs, hnRNP F transfection","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (ChIP, siRNA, reporter assays), replicated across multiple constructs","pmids":["19749764"],"is_preprint":false},{"year":2012,"finding":"Siah1 (but not Siah2) is the E3 ubiquitin ligase responsible for ELL2 polyubiquitination and proteasomal degradation; AFF4-bound ELL2 is protected from Siah1-mediated ubiquitination; Prostratin and HMBA enhance ELL2 accumulation and super elongation complex (SEC) formation by reducing Siah1 expression.","method":"Co-immunoprecipitation, ubiquitination assays, proteasome inhibitor experiments, siRNA knockdown","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, ubiquitination assays, and functional rescue experiments in one rigorous study","pmids":["22483617"],"is_preprint":false},{"year":2012,"finding":"ELL2 modulates the ratio of secreted versus membrane-encoding Ighg2b transcripts in plasma cells, counteracting hnRNPLL; approximately 12% of plasma cell transcripts are differentially processed due to ELL2 activity, including BCMA mRNA.","method":"Lentiviral shRNA screen, RNA-Seq, transfection-based isoform analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — shRNA screen plus RNA-Seq with functional validation, replicated across multiple transcripts","pmids":["22991471"],"is_preprint":false},{"year":2011,"finding":"ELL2 knockdown reduced H3K4 and H3K79 methylations on the IgH gene, impaired pTEFb Ser-2 CTD phosphorylation, and reduced polyadenylation factor additions to RNA pol II; MLL and Dot1L associations with the IgH gene were also impaired without ELL2.","method":"siRNA knockdown, chromatin immunoprecipitation (ChIP), comparison of B cells versus plasma cells","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP with multiple histone marks, single lab, multiple orthogonal readouts","pmids":["21832080"],"is_preprint":false},{"year":2014,"finding":"B cell-specific conditional knockout of ELL2 in mice curtailed humoral responses, reduced plasma cells in spleen, caused distended endoplasmic reticulum in ELL2-deficient plasma cells, and severely reduced XBP1, ATF6, BiP, and secreted IgH mRNA levels; ELL2 also enhances BCMA expression important for plasma cell survival.","method":"Conditional knockout mouse model (Cre/loxP with CD19-Cre), ex vivo stimulation, immunization, flow cytometry, qPCR, electron microscopy","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean conditional KO with multiple cellular and molecular phenotypic readouts, in vivo and ex vivo","pmids":["25238757"],"is_preprint":false},{"year":2015,"finding":"The MM risk allele (rs56219066T) harbors a Thr298Ala missense variant in the ELL2 transcription elongation domain; the risk allele associates with reduced IgA and IgG levels, consistent with hypomorphic ELL2 function as a stoichiometrically limiting component of the super elongation complex in plasma cells.","method":"Genome-wide association study, functional domain mapping (missense variant in known elongation domain)","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — genetic association with domain mapping, no direct in vitro assay of the variant's elongation activity","pmids":["26007630"],"is_preprint":false},{"year":2017,"finding":"Crystal structure (2.0-Å resolution) of the ELL2 C-terminal domain bound to the 50-residue ELLBow region of AFF4 was determined; the ELL2 C-terminal domain adopts an arch-shaped fold homologous to occludin, and the AFF4 ELLBow occupies the concave surface of ELL2; this interface is required for ELL2's ability to promote HIV-1 Tat-mediated proviral transcription.","method":"X-ray crystallography, mutagenesis of binding interface, HIV-1 Tat transactivation assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure at 2.0 Å combined with mutagenesis and functional transactivation assay","pmids":["28134250"],"is_preprint":false},{"year":2017,"finding":"ELL2 knockdown sensitized prostate cancer cells to DNA damage and impaired non-homologous end joining (NHEJ) repair (but not homologous recombination); ELL2 co-immunoprecipitated with Ku70 and Ku80 and co-accumulated with Ku70/Ku80 at DNA double-strand break sites; ELL2 knockdown inhibited Ku70/Ku80 recruitment to DSBs, rescued by siRNA-resistant ELL2 re-expression.","method":"Co-immunoprecipitation, NHEJ/HR repair assays, immunofluorescence at DSB sites, siRNA knockdown and rescue","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with functional NHEJ assay and rescue experiment, single lab","pmids":["29179998"],"is_preprint":false},{"year":2017,"finding":"ELL2 physically interacts with RB; this interaction is mediated through the N-terminus of ELL2 and C-terminus of RB; RB binding stabilizes ELL2; concurrent siRNA knockdown of ELL2 and RB enhanced prostate cancer cell proliferation, migration, and invasion more than knockdown of either alone.","method":"Co-immunoprecipitation, deletion mutagenesis, siRNA knockdown, BrdU incorporation, Transwell/invasion assays","journal":"Neoplasia (New York, N.Y.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with deletion mapping plus functional epistasis assays, single lab","pmids":["28167296"],"is_preprint":false},{"year":2017,"finding":"Conditional prostate-specific deletion of ELL2 in mice induced murine prostatic intraepithelial neoplasia (mPIN), with increased epithelial proliferation, vascularity, and PIN lesions; microarray identified differentially expressed genes associated with proliferation and motility.","method":"Conditional knockout mouse model, histology, microarray, qPCR","journal":"The Journal of endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean conditional KO with defined in vivo phenotype, single lab","pmids":["28870994"],"is_preprint":false},{"year":2018,"finding":"ELL2 has a short protein half-life and is degraded via the proteasome; lysine residues K584 and K599 are important for ELL2 polyubiquitination and degradation; EAF2 binding stabilizes ELL2 and inhibits its polyubiquitination.","method":"Proteasome inhibitor (MG132) treatment, deletion and site-directed mutagenesis, ubiquitination assays, co-immunoprecipitation with EAF2","journal":"The Prostate","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis combined with ubiquitination assay and protein stability measurements, single lab","pmids":["30009504"],"is_preprint":false},{"year":2014,"finding":"ELL2 is specifically upregulated in HTLV-1-/Tax-transformed T-cells; Tax transactivates the ELL2 promoter; Tax and ELL2 co-precipitate upon co-expression and accumulate in nuclear fractions; Tax and ELL2 synergistically activate the HTLV-1 promoter.","method":"qRT-PCR, promoter-luciferase assay, co-immunoprecipitation, cell fractionation","journal":"Virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with luciferase reporter and fractionation, single lab, multiple methods","pmids":["25058508"],"is_preprint":false},{"year":2020,"finding":"HCF1 and HCF2 suppress Siah1/2 ubiquitin ligase activity by binding and blocking the substrate-binding domain (SBD) of Siah1/2 (without being degraded themselves), thereby stabilizing ELL2 and enhancing SEC formation for robust HIV-1 transactivation.","method":"Co-immunoprecipitation, ubiquitination assays, HIV-1 transactivation reporter assays, ELL2 stability measurements","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal assays (Co-IP, ubiquitination, functional transactivation), single lab","pmids":["32479599"],"is_preprint":false},{"year":2018,"finding":"ELL2 splicing activity accounts for approximately 55% of splicing changes observed during B cell to antibody-secreting cell transition; some changes occur when ELL2 binds directly to target genes, while others are indirect; ELL2-dependent splicing affects cell-cycle and N-glycan biosynthesis pathway genes.","method":"Splicing array, conditional ELL2 knockout B cells, LPS stimulation ex vivo, ChIP","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — splicing array with conditional KO validation and ChIP, single lab","pmids":["30297340"],"is_preprint":false},{"year":2021,"finding":"Tax-1 interacts with ELL2 via N-terminal (aa 1-37) and C-terminal (aa 150-353) regions of Tax-1; ELL2 region R1 (aa 1-353, containing the RNA pol II binding domain) is sufficient for Tax-1 interaction and for enhancing Tax-1-mediated HTLV-1 promoter transactivation; ELL2 R3 (aa 515-640) can bind Tax-1 but cannot enhance transactivation; Tax-1 and ELL2 co-localize in dot-like nuclear structures.","method":"Co-immunoprecipitation, deletion mutagenesis, confocal microscopy, luciferase reporter assay","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with domain mapping, co-localization, and functional luciferase assay, single lab","pmids":["34948391"],"is_preprint":false},{"year":2024,"finding":"ELL2 contains a functional bipartite nuclear localization signal (NLS) at amino acids 311-338 within the conserved R1 region; key basic residues K319, R320, and K333/K334 are required for nuclear accumulation; the isolated NLS is sufficient to translocate an unrelated protein into the nucleus.","method":"Confocal laser scanning microscopy of truncation mutants, site-directed mutagenesis of NLS residues, NLS-mapping fusion construct","journal":"Cell biochemistry and function","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis combined with imaging and functional NLS transfer experiment, single lab","pmids":["39582094"],"is_preprint":false},{"year":2026,"finding":"ELL2 and POU2AF1 form an autoregulatory loop with IRF4 downstream of IL-6/JAK/STAT3 signaling, establishing an MM-distinct transcriptional program; POU2AF1 and ELL2 are essential for IL-6-dependent alternative RNA splicing and MM cell growth; POU2AF1 co-localizes with and facilitates nuclear speckle formation, interacting with trans-acting splicing factors.","method":"ChIP-seq, RNA-seq, CRISPR knockout screening, xenograft model, immunocytochemistry, proteomics","journal":"Blood advances","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR KO with ChIP-seq and RNA-seq plus in vivo xenograft, single lab, multiple orthogonal methods","pmids":["41925579"],"is_preprint":false}],"current_model":"ELL2 is a stoichiometrically limiting subunit of the Super Elongation Complex (SEC) that suppresses RNA polymerase II pausing; its C-terminal domain binds AFF4 (ELLBow) in an arch-shaped fold, and together they drive transcriptional elongation and stimulate altered RNA processing (proximal poly(A) site use and exon skipping) in plasma cells to generate secretory immunoglobulin heavy-chain mRNA; ELL2 stability is controlled by Siah1-mediated polyubiquitination (at K584/K599) and proteasomal degradation, which is counteracted by AFF4 binding or EAF2 binding, and by HCF1/2 blocking Siah1's substrate-binding domain; ELL2 also interacts physically with Ku70/Ku80 to facilitate non-homologous end joining DNA repair and with RB to suppress prostate cell proliferation, and it localizes to the nucleus via a bipartite NLS at residues 311–338."},"narrative":{"mechanistic_narrative":"ELL2 is an RNA polymerase II transcription elongation factor that stimulates productive elongation through an N-terminal elongation activation domain [PMID:9108030] and operates as a stoichiometrically limiting subunit of the Super Elongation Complex (SEC), where its C-terminal domain adopts an arch-shaped, occludin-like fold that binds the ELLBow region of AFF4 across a concave surface required for SEC-driven proviral HIV-1 Tat transactivation [PMID:28134250]. In plasma cells, ELL2 couples elongation to altered RNA processing: it promotes use of the promoter-proximal poly(A) site and exon skipping in immunoglobulin heavy-chain pre-mRNA by co-tracking with RNA polymerase II and the polyadenylation factor CstF-64, and ELL2 is required for their co-loading across the Igh locus [PMID:19749764]. ELL2 thereby sets the secreted-versus-membrane transcript ratio, shapes a broad alternative splicing program during the B-cell to antibody-secreting-cell transition affecting cell-cycle and N-glycan biosynthesis genes, and enhances BCMA expression [PMID:22991471, PMID:30297340]. ELL2 promotes co-transcriptional deposition of H3K4 and H3K79 methylation and pTEFb-dependent Ser2 CTD phosphorylation at the IgH gene [PMID:21832080], and B-cell-specific deletion in mice curtails humoral responses, depletes plasma cells, and collapses the secretory unfolded-protein-response program (XBP1, ATF6, BiP) [PMID:25238757]. ELL2 abundance is governed by rapid proteasomal turnover: Siah1 polyubiquitinates ELL2 at K584/K599, while AFF4 binding, EAF2 binding, and HCF1/HCF2 blockade of the Siah1 substrate-binding domain all stabilize the protein and enhance SEC formation [PMID:22483617, PMID:30009504, PMID:32479599]. Beyond transcription, ELL2 interacts with Ku70/Ku80 to facilitate their recruitment to double-strand breaks and non-homologous end joining [PMID:29179998] and binds RB to suppress prostate epithelial proliferation, with prostate-specific deletion inducing prostatic intraepithelial neoplasia [PMID:28167296, PMID:28870994]. A hypomorphic Thr298Ala variant in the elongation domain associates with multiple myeloma risk and reduced immunoglobulin levels [PMID:26007630].","teleology":[{"year":1997,"claim":"Established ELL2 as a bona fide RNA polymerase II elongation factor and localized its activity to an N-terminal elongation activation domain, defining its core biochemical function.","evidence":"In vitro transcription assays with truncation mutants","pmids":["9108030"],"confidence":"High","gaps":["Did not define partner complexes (SEC) in which ELL2 acts in cells","No structural basis for activity"]},{"year":2009,"claim":"Connected ELL2's elongation activity to RNA processing fate, showing it directs proximal poly(A) site use and exon skipping in IgH pre-mRNA via co-loading of CstF-64 with RNA pol II.","evidence":"siRNA knockdown, ChIP, reporter constructs in plasma cells","pmids":["19749764"],"confidence":"High","gaps":["Mechanism by which ELL2 recruits CstF-64 not resolved","Restricted to IgH locus initially"]},{"year":2011,"claim":"Linked ELL2 to chromatin and CTD modification, showing its loss reduces H3K4/H3K79 methylation, Ser2 CTD phosphorylation, and MLL/Dot1L association at the IgH gene.","evidence":"siRNA knockdown and ChIP comparing B cells versus plasma cells","pmids":["21832080"],"confidence":"Medium","gaps":["Direct versus indirect recruitment of MLL/Dot1L unclear","Single locus, single lab"]},{"year":2012,"claim":"Identified Siah1 as the E3 ligase controlling ELL2 turnover and showed AFF4 binding protects ELL2, establishing degradation as a rheostat for SEC assembly.","evidence":"Reciprocal Co-IP, ubiquitination assays, proteasome inhibition, siRNA","pmids":["22483617"],"confidence":"High","gaps":["Ubiquitinated lysines not yet mapped","Upstream regulation of Siah1 in physiological settings unclear"]},{"year":2012,"claim":"Quantified the breadth of ELL2-dependent transcript processing in plasma cells, showing it sets secreted/membrane Ig isoform ratios and affects ~12% of transcripts including BCMA.","evidence":"Lentiviral shRNA screen, RNA-Seq, isoform analysis","pmids":["22991471"],"confidence":"High","gaps":["Direct versus indirect target distinction incomplete","Mechanism counteracting hnRNPLL not resolved"]},{"year":2014,"claim":"Demonstrated ELL2 is required in vivo for plasma cell differentiation and the secretory program, tying its molecular activity to humoral immunity.","evidence":"CD19-Cre conditional knockout mice, immunization, flow cytometry, electron microscopy","pmids":["25238757"],"confidence":"High","gaps":["Causal chain from ELL2 loss to XBP1/ATF6 collapse not mechanistically dissected"]},{"year":2014,"claim":"Revealed a viral co-option of ELL2, with HTLV-1 Tax transactivating the ELL2 promoter and forming a nuclear complex that synergistically activates the HTLV-1 LTR.","evidence":"qRT-PCR, promoter-luciferase, Co-IP, cell fractionation","pmids":["25058508"],"confidence":"Medium","gaps":["Interaction interface not yet mapped","Single lab"]},{"year":2015,"claim":"Provided human genetic evidence that a hypomorphic missense variant in the ELL2 elongation domain confers multiple myeloma risk and lowers immunoglobulin levels.","evidence":"Genome-wide association study with functional domain mapping","pmids":["26007630"],"confidence":"Medium","gaps":["No direct in vitro assay of variant elongation activity","Causality at the cellular level inferred"]},{"year":2017,"claim":"Solved the structural basis of ELL2 incorporation into the SEC, showing its C-terminal arch-shaped fold binds the AFF4 ELLBow, an interface required for HIV-1 Tat transactivation.","evidence":"2.0-Å X-ray crystallography, interface mutagenesis, Tat transactivation assay","pmids":["28134250"],"confidence":"High","gaps":["Structure limited to the C-terminal/AFF4 interface; full-length and pol II-bound architecture unknown"]},{"year":2017,"claim":"Uncovered a transcription-independent role for ELL2 in DNA repair, recruiting Ku70/Ku80 to double-strand breaks to support non-homologous end joining.","evidence":"Co-IP, NHEJ/HR assays, immunofluorescence at DSBs, siRNA knockdown and rescue","pmids":["29179998"],"confidence":"Medium","gaps":["Whether ELL2's elongation function is required for NHEJ unclear","Single lab"]},{"year":2017,"claim":"Identified an RB-ELL2 interaction and a tumor-suppressive role in prostate cells, with co-loss enhancing proliferation, migration, and invasion.","evidence":"Co-IP, deletion mapping, siRNA, BrdU and invasion assays","pmids":["28167296"],"confidence":"Medium","gaps":["Mechanism by which RB binding suppresses proliferation unresolved"]},{"year":2017,"claim":"Confirmed ELL2 as a prostate tumor suppressor in vivo, with prostate-specific deletion driving prostatic intraepithelial neoplasia.","evidence":"Conditional knockout mouse, histology, microarray, qPCR","pmids":["28870994"],"confidence":"Medium","gaps":["Link between transcriptional targets and PIN phenotype correlative"]},{"year":2018,"claim":"Mapped the ELL2 degron, identifying K584/K599 as ubiquitination sites and EAF2 as a stabilizing partner, refining the post-translational control of ELL2 levels.","evidence":"MG132 treatment, site-directed mutagenesis, ubiquitination assays, Co-IP with EAF2","pmids":["30009504"],"confidence":"Medium","gaps":["Whether EAF2 and AFF4 stabilize via the same mechanism unclear"]},{"year":2018,"claim":"Defined the genome-wide scope of ELL2-dependent splicing in the antibody-secreting-cell transition, attributing ~55% of splicing changes to ELL2 and distinguishing direct from indirect effects.","evidence":"Splicing array, conditional ELL2 knockout B cells, ChIP","pmids":["30297340"],"confidence":"Medium","gaps":["Mechanistic basis for indirect splicing changes unknown"]},{"year":2020,"claim":"Established HCF1/HCF2 as stabilizers of ELL2 by blocking the Siah1/2 substrate-binding domain, adding a layer to SEC abundance control relevant to HIV-1 transactivation.","evidence":"Co-IP, ubiquitination assays, HIV-1 transactivation reporter, stability measurements","pmids":["32479599"],"confidence":"Medium","gaps":["Physiological contexts triggering HCF-mediated stabilization unclear"]},{"year":2021,"claim":"Mapped the Tax-1/ELL2 interaction to the ELL2 R1 region containing the pol II-binding domain, distinguishing binding from functional transactivation enhancement.","evidence":"Co-IP, deletion mutagenesis, confocal microscopy, luciferase reporter","pmids":["34948391"],"confidence":"Medium","gaps":["Why R3 binds but does not enhance transactivation unresolved"]},{"year":2024,"claim":"Identified a functional bipartite NLS at residues 311-338 within R1, explaining how ELL2 reaches the nucleus to perform its functions.","evidence":"Confocal imaging of truncation/NLS mutants, NLS-transfer fusion construct","pmids":["39582094"],"confidence":"Medium","gaps":["Import receptor not identified","Regulation of nuclear import unknown"]},{"year":2026,"claim":"Placed ELL2 in an IL-6/STAT3-driven autoregulatory transcriptional loop with POU2AF1 and IRF4 that sustains multiple myeloma growth and IL-6-dependent alternative splicing.","evidence":"ChIP-seq, RNA-seq, CRISPR knockout screen, xenograft, proteomics","pmids":["41925579"],"confidence":"Medium","gaps":["Direct ELL2-POU2AF1 physical interaction not fully defined","Mechanism linking the loop to specific MM splicing targets incomplete"]},{"year":null,"claim":"How ELL2's elongation activity is mechanistically coupled to its choice of poly(A) site and splice site, and whether its DNA-repair and tumor-suppressor roles depend on the same SEC machinery, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of full-length ELL2 in the pol II-engaged SEC","Coupling logic between elongation and RNA processing decisions undefined","Functional separability of transcription versus NHEJ/RB roles untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,7]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,2]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[7,8]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[16,12]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[15]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,7]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[1,3,14]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[5,3]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[8]}],"complexes":["Super Elongation Complex (SEC)"],"partners":["AFF4","SIAH1","EAF2","HCF1","HCF2","KU70","KU80","RB1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O00472","full_name":"RNA polymerase II elongation factor ELL2","aliases":[],"length_aa":640,"mass_kda":72.3,"function":"Elongation factor component of the super elongation complex (SEC), a complex required to increase the catalytic rate of RNA polymerase II transcription by suppressing transient pausing by the polymerase at multiple sites along the DNA. Component of the little elongation complex (LEC), a complex required to regulate small nuclear RNA (snRNA) gene transcription by RNA polymerase II and III (PubMed:22195968). Plays a role in immunoglobulin secretion in plasma cells: directs efficient alternative mRNA processing, influencing both proximal poly(A) site choice and exon skipping, as well as immunoglobulin heavy chain (IgH) alternative processing. Probably acts by regulating histone modifications accompanying transition from membrane-specific to secretory IgH mRNA expression","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/O00472/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ELL2","classification":"Not Classified","n_dependent_lines":9,"n_total_lines":1208,"dependency_fraction":0.0074503311258278145},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ELL2","total_profiled":1310},"omim":[{"mim_id":"609885","title":"ELONGATION FACTOR, RNA POLYMERASE II, 3; ELL3","url":"https://www.omim.org/entry/609885"},{"mim_id":"608315","title":"ELL-ASSOCIATED FACTOR 1; EAF1","url":"https://www.omim.org/entry/608315"},{"mim_id":"601874","title":"ELONGATION FACTOR, RNA POLYMERASE II, 2; ELL2","url":"https://www.omim.org/entry/601874"},{"mim_id":"254500","title":"MYELOMA, MULTIPLE","url":"https://www.omim.org/entry/254500"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ELL2"},"hgnc":{"alias_symbol":["MRCCAT1"],"prev_symbol":[]},"alphafold":{"accession":"O00472","domains":[{"cath_id":"-","chopping":"31-136","consensus_level":"high","plddt":83.4542,"start":31,"end":136},{"cath_id":"1.10.10.2670","chopping":"207-291","consensus_level":"high","plddt":86.6732,"start":207,"end":291},{"cath_id":"-","chopping":"528-640","consensus_level":"high","plddt":92.7758,"start":528,"end":640}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O00472","model_url":"https://alphafold.ebi.ac.uk/files/AF-O00472-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O00472-F1-predicted_aligned_error_v6.png","plddt_mean":65.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ELL2","jax_strain_url":"https://www.jax.org/strain/search?query=ELL2"},"sequence":{"accession":"O00472","fasta_url":"https://rest.uniprot.org/uniprotkb/O00472.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O00472/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O00472"}},"corpus_meta":[{"pmid":"28659173","id":"PMC_28659173","title":"Long noncoding RNA MRCCAT1 promotes metastasis of clear cell renal cell carcinoma via inhibiting NPR3 and activating p38-MAPK signaling.","date":"2017","source":"Molecular cancer","url":"https://pubmed.ncbi.nlm.nih.gov/28659173","citation_count":186,"is_preprint":false},{"pmid":"9108030","id":"PMC_9108030","title":"ELL2, a new member of an ELL family of RNA polymerase II elongation factors.","date":"1997","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9108030","citation_count":112,"is_preprint":false},{"pmid":"19749764","id":"PMC_19749764","title":"Transcription elongation factor ELL2 directs immunoglobulin secretion in plasma cells by stimulating altered RNA processing.","date":"2009","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/19749764","citation_count":110,"is_preprint":false},{"pmid":"26007630","id":"PMC_26007630","title":"Variants in ELL2 influencing immunoglobulin levels associate with multiple myeloma.","date":"2015","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/26007630","citation_count":73,"is_preprint":false},{"pmid":"22483617","id":"PMC_22483617","title":"The ubiquitin ligase Siah1 controls ELL2 stability and formation of super elongation complexes to modulate gene transcription.","date":"2012","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/22483617","citation_count":57,"is_preprint":false},{"pmid":"25238757","id":"PMC_25238757","title":"Transcription elongation factor ELL2 drives Ig secretory-specific mRNA production and the unfolded protein response.","date":"2014","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/25238757","citation_count":42,"is_preprint":false},{"pmid":"22991471","id":"PMC_22991471","title":"Heterogeneous nuclear ribonucleoprotein L-like (hnRNPLL) and elongation factor, RNA polymerase II, 2 (ELL2) are regulators of mRNA processing in plasma cells.","date":"2012","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/22991471","citation_count":35,"is_preprint":false},{"pmid":"28134250","id":"PMC_28134250","title":"Structural basis for ELL2 and AFF4 activation of HIV-1 proviral transcription.","date":"2017","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/28134250","citation_count":32,"is_preprint":false},{"pmid":"30297340","id":"PMC_30297340","title":"RNA Splicing in the Transition from B Cells to Antibody-Secreting Cells: The Influences of ELL2, Small Nuclear RNA, and Endoplasmic Reticulum Stress.","date":"2018","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/30297340","citation_count":19,"is_preprint":false},{"pmid":"28903037","id":"PMC_28903037","title":"Genetic Predisposition to Multiple Myeloma at 5q15 Is Mediated by an ELL2 Enhancer Polymorphism.","date":"2017","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/28903037","citation_count":18,"is_preprint":false},{"pmid":"29179998","id":"PMC_29179998","title":"ELL2 regulates DNA non-homologous end joining (NHEJ) repair in prostate cancer cells.","date":"2017","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/29179998","citation_count":17,"is_preprint":false},{"pmid":"32479599","id":"PMC_32479599","title":"Host cell factors stimulate HIV-1 transcription by antagonizing substrate-binding function of Siah1 ubiquitin ligase to stabilize transcription elongation factor ELL2.","date":"2020","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/32479599","citation_count":17,"is_preprint":false},{"pmid":"21832080","id":"PMC_21832080","title":"The eleven-nineteen lysine-rich leukemia gene (ELL2) influences the histone H3 protein modifications accompanying the shift to secretory immunoglobulin heavy chain mRNA production.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21832080","citation_count":17,"is_preprint":false},{"pmid":"28167296","id":"PMC_28167296","title":"Physical and Functional Interactions between ELL2 and RB in the Suppression of Prostate Cancer Cell Proliferation, Migration, and Invasion.","date":"2017","source":"Neoplasia (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/28167296","citation_count":16,"is_preprint":false},{"pmid":"28858629","id":"PMC_28858629","title":"Selective expression of the transcription elongation factor ELL3 in B cells prior to ELL2 drives proliferation and survival.","date":"2017","source":"Molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/28858629","citation_count":13,"is_preprint":false},{"pmid":"25058508","id":"PMC_25058508","title":"The transcription elongation factor ELL2 is specifically upregulated in HTLV-1-infected T-cells and is dependent on the viral oncoprotein Tax.","date":"2014","source":"Virology","url":"https://pubmed.ncbi.nlm.nih.gov/25058508","citation_count":13,"is_preprint":false},{"pmid":"28870994","id":"PMC_28870994","title":"Conditional deletion of ELL2 induces murine prostate intraepithelial neoplasia.","date":"2017","source":"The Journal of endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/28870994","citation_count":11,"is_preprint":false},{"pmid":"32606936","id":"PMC_32606936","title":"ELL2 Is Required for the Growth and Survival of AR-Negative Prostate Cancer Cells.","date":"2020","source":"Cancer management and research","url":"https://pubmed.ncbi.nlm.nih.gov/32606936","citation_count":8,"is_preprint":false},{"pmid":"31511829","id":"PMC_31511829","title":"Anti-apoptotic factor Birc3 is up-regulated by ELL2 knockdown and stimulates proliferation in LNCaP cells.","date":"2019","source":"American journal of clinical and experimental urology","url":"https://pubmed.ncbi.nlm.nih.gov/31511829","citation_count":8,"is_preprint":false},{"pmid":"30009504","id":"PMC_30009504","title":"Regulation of ELL2 stability and polyubiquitination by EAF2 in prostate cancer cells.","date":"2018","source":"The Prostate","url":"https://pubmed.ncbi.nlm.nih.gov/30009504","citation_count":7,"is_preprint":false},{"pmid":"31930204","id":"PMC_31930204","title":"ELL2 Influences Transcription Elongation, Splicing, Ig Secretion and Growth.","date":"2019","source":"Journal of mucosal immunology research","url":"https://pubmed.ncbi.nlm.nih.gov/31930204","citation_count":7,"is_preprint":false},{"pmid":"30697579","id":"PMC_30697579","title":"Concurrent EAF2 and ELL2 loss phenocopies individual EAF2 or ELL2 loss in prostate cancer cells and murine prostate.","date":"2018","source":"American journal of clinical and experimental urology","url":"https://pubmed.ncbi.nlm.nih.gov/30697579","citation_count":6,"is_preprint":false},{"pmid":"34948391","id":"PMC_34948391","title":"Characterizing the Interaction between the HTLV-1 Transactivator Tax-1 with Transcription Elongation Factor ELL2 and Its Impact on Viral Transactivation.","date":"2021","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/34948391","citation_count":2,"is_preprint":false},{"pmid":"31275443","id":"PMC_31275443","title":"ELL2 Is Downregulated and Associated with Galactose-Deficient IgA1 in IgA Nephropathy.","date":"2019","source":"Disease markers","url":"https://pubmed.ncbi.nlm.nih.gov/31275443","citation_count":1,"is_preprint":false},{"pmid":"39582094","id":"PMC_39582094","title":"Identification of a Nuclear Localization Signal (NLS) in Human Transcription Elongation Factor ELL2.","date":"2024","source":"Cell biochemistry and function","url":"https://pubmed.ncbi.nlm.nih.gov/39582094","citation_count":0,"is_preprint":false},{"pmid":"41925579","id":"PMC_41925579","title":"IL-6-driven POU2AF1 and ELL2 are key regulators of multiple myeloma-distinct transcriptional and splicing programs.","date":"2026","source":"Blood advances","url":"https://pubmed.ncbi.nlm.nih.gov/41925579","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14430,"output_tokens":4275,"usd":0.053707,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12223,"output_tokens":4993,"usd":0.09297,"stage2_stop_reason":"end_turn"},"total_usd":0.146677,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"ELL2 is a RNA polymerase II elongation factor that stimulates transcriptional elongation, with its elongation activation domain localized to its N-terminal region (homologous to ELL).\",\n      \"method\": \"In vitro transcription assays, structure-function studies with truncation mutants\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro transcription assay with domain mapping via mutagenesis, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"9108030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"ELL2 (induced in plasma cells) stimulates use of the promoter-proximal poly(A) site and exon skipping in the immunoglobulin heavy-chain pre-mRNA; ELL2 and polyadenylation factor CstF-64 co-track with RNA polymerase II across Igh gene segments, and this co-loading requires ELL2.\",\n      \"method\": \"siRNA knockdown, chromatin immunoprecipitation (ChIP), reporter constructs, hnRNP F transfection\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (ChIP, siRNA, reporter assays), replicated across multiple constructs\",\n      \"pmids\": [\"19749764\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Siah1 (but not Siah2) is the E3 ubiquitin ligase responsible for ELL2 polyubiquitination and proteasomal degradation; AFF4-bound ELL2 is protected from Siah1-mediated ubiquitination; Prostratin and HMBA enhance ELL2 accumulation and super elongation complex (SEC) formation by reducing Siah1 expression.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, proteasome inhibitor experiments, siRNA knockdown\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, ubiquitination assays, and functional rescue experiments in one rigorous study\",\n      \"pmids\": [\"22483617\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"ELL2 modulates the ratio of secreted versus membrane-encoding Ighg2b transcripts in plasma cells, counteracting hnRNPLL; approximately 12% of plasma cell transcripts are differentially processed due to ELL2 activity, including BCMA mRNA.\",\n      \"method\": \"Lentiviral shRNA screen, RNA-Seq, transfection-based isoform analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — shRNA screen plus RNA-Seq with functional validation, replicated across multiple transcripts\",\n      \"pmids\": [\"22991471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ELL2 knockdown reduced H3K4 and H3K79 methylations on the IgH gene, impaired pTEFb Ser-2 CTD phosphorylation, and reduced polyadenylation factor additions to RNA pol II; MLL and Dot1L associations with the IgH gene were also impaired without ELL2.\",\n      \"method\": \"siRNA knockdown, chromatin immunoprecipitation (ChIP), comparison of B cells versus plasma cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP with multiple histone marks, single lab, multiple orthogonal readouts\",\n      \"pmids\": [\"21832080\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"B cell-specific conditional knockout of ELL2 in mice curtailed humoral responses, reduced plasma cells in spleen, caused distended endoplasmic reticulum in ELL2-deficient plasma cells, and severely reduced XBP1, ATF6, BiP, and secreted IgH mRNA levels; ELL2 also enhances BCMA expression important for plasma cell survival.\",\n      \"method\": \"Conditional knockout mouse model (Cre/loxP with CD19-Cre), ex vivo stimulation, immunization, flow cytometry, qPCR, electron microscopy\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean conditional KO with multiple cellular and molecular phenotypic readouts, in vivo and ex vivo\",\n      \"pmids\": [\"25238757\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The MM risk allele (rs56219066T) harbors a Thr298Ala missense variant in the ELL2 transcription elongation domain; the risk allele associates with reduced IgA and IgG levels, consistent with hypomorphic ELL2 function as a stoichiometrically limiting component of the super elongation complex in plasma cells.\",\n      \"method\": \"Genome-wide association study, functional domain mapping (missense variant in known elongation domain)\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — genetic association with domain mapping, no direct in vitro assay of the variant's elongation activity\",\n      \"pmids\": [\"26007630\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Crystal structure (2.0-Å resolution) of the ELL2 C-terminal domain bound to the 50-residue ELLBow region of AFF4 was determined; the ELL2 C-terminal domain adopts an arch-shaped fold homologous to occludin, and the AFF4 ELLBow occupies the concave surface of ELL2; this interface is required for ELL2's ability to promote HIV-1 Tat-mediated proviral transcription.\",\n      \"method\": \"X-ray crystallography, mutagenesis of binding interface, HIV-1 Tat transactivation assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure at 2.0 Å combined with mutagenesis and functional transactivation assay\",\n      \"pmids\": [\"28134250\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ELL2 knockdown sensitized prostate cancer cells to DNA damage and impaired non-homologous end joining (NHEJ) repair (but not homologous recombination); ELL2 co-immunoprecipitated with Ku70 and Ku80 and co-accumulated with Ku70/Ku80 at DNA double-strand break sites; ELL2 knockdown inhibited Ku70/Ku80 recruitment to DSBs, rescued by siRNA-resistant ELL2 re-expression.\",\n      \"method\": \"Co-immunoprecipitation, NHEJ/HR repair assays, immunofluorescence at DSB sites, siRNA knockdown and rescue\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with functional NHEJ assay and rescue experiment, single lab\",\n      \"pmids\": [\"29179998\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ELL2 physically interacts with RB; this interaction is mediated through the N-terminus of ELL2 and C-terminus of RB; RB binding stabilizes ELL2; concurrent siRNA knockdown of ELL2 and RB enhanced prostate cancer cell proliferation, migration, and invasion more than knockdown of either alone.\",\n      \"method\": \"Co-immunoprecipitation, deletion mutagenesis, siRNA knockdown, BrdU incorporation, Transwell/invasion assays\",\n      \"journal\": \"Neoplasia (New York, N.Y.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with deletion mapping plus functional epistasis assays, single lab\",\n      \"pmids\": [\"28167296\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Conditional prostate-specific deletion of ELL2 in mice induced murine prostatic intraepithelial neoplasia (mPIN), with increased epithelial proliferation, vascularity, and PIN lesions; microarray identified differentially expressed genes associated with proliferation and motility.\",\n      \"method\": \"Conditional knockout mouse model, histology, microarray, qPCR\",\n      \"journal\": \"The Journal of endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean conditional KO with defined in vivo phenotype, single lab\",\n      \"pmids\": [\"28870994\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ELL2 has a short protein half-life and is degraded via the proteasome; lysine residues K584 and K599 are important for ELL2 polyubiquitination and degradation; EAF2 binding stabilizes ELL2 and inhibits its polyubiquitination.\",\n      \"method\": \"Proteasome inhibitor (MG132) treatment, deletion and site-directed mutagenesis, ubiquitination assays, co-immunoprecipitation with EAF2\",\n      \"journal\": \"The Prostate\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis combined with ubiquitination assay and protein stability measurements, single lab\",\n      \"pmids\": [\"30009504\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"ELL2 is specifically upregulated in HTLV-1-/Tax-transformed T-cells; Tax transactivates the ELL2 promoter; Tax and ELL2 co-precipitate upon co-expression and accumulate in nuclear fractions; Tax and ELL2 synergistically activate the HTLV-1 promoter.\",\n      \"method\": \"qRT-PCR, promoter-luciferase assay, co-immunoprecipitation, cell fractionation\",\n      \"journal\": \"Virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with luciferase reporter and fractionation, single lab, multiple methods\",\n      \"pmids\": [\"25058508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"HCF1 and HCF2 suppress Siah1/2 ubiquitin ligase activity by binding and blocking the substrate-binding domain (SBD) of Siah1/2 (without being degraded themselves), thereby stabilizing ELL2 and enhancing SEC formation for robust HIV-1 transactivation.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, HIV-1 transactivation reporter assays, ELL2 stability measurements\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal assays (Co-IP, ubiquitination, functional transactivation), single lab\",\n      \"pmids\": [\"32479599\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ELL2 splicing activity accounts for approximately 55% of splicing changes observed during B cell to antibody-secreting cell transition; some changes occur when ELL2 binds directly to target genes, while others are indirect; ELL2-dependent splicing affects cell-cycle and N-glycan biosynthesis pathway genes.\",\n      \"method\": \"Splicing array, conditional ELL2 knockout B cells, LPS stimulation ex vivo, ChIP\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — splicing array with conditional KO validation and ChIP, single lab\",\n      \"pmids\": [\"30297340\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Tax-1 interacts with ELL2 via N-terminal (aa 1-37) and C-terminal (aa 150-353) regions of Tax-1; ELL2 region R1 (aa 1-353, containing the RNA pol II binding domain) is sufficient for Tax-1 interaction and for enhancing Tax-1-mediated HTLV-1 promoter transactivation; ELL2 R3 (aa 515-640) can bind Tax-1 but cannot enhance transactivation; Tax-1 and ELL2 co-localize in dot-like nuclear structures.\",\n      \"method\": \"Co-immunoprecipitation, deletion mutagenesis, confocal microscopy, luciferase reporter assay\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with domain mapping, co-localization, and functional luciferase assay, single lab\",\n      \"pmids\": [\"34948391\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ELL2 contains a functional bipartite nuclear localization signal (NLS) at amino acids 311-338 within the conserved R1 region; key basic residues K319, R320, and K333/K334 are required for nuclear accumulation; the isolated NLS is sufficient to translocate an unrelated protein into the nucleus.\",\n      \"method\": \"Confocal laser scanning microscopy of truncation mutants, site-directed mutagenesis of NLS residues, NLS-mapping fusion construct\",\n      \"journal\": \"Cell biochemistry and function\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis combined with imaging and functional NLS transfer experiment, single lab\",\n      \"pmids\": [\"39582094\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ELL2 and POU2AF1 form an autoregulatory loop with IRF4 downstream of IL-6/JAK/STAT3 signaling, establishing an MM-distinct transcriptional program; POU2AF1 and ELL2 are essential for IL-6-dependent alternative RNA splicing and MM cell growth; POU2AF1 co-localizes with and facilitates nuclear speckle formation, interacting with trans-acting splicing factors.\",\n      \"method\": \"ChIP-seq, RNA-seq, CRISPR knockout screening, xenograft model, immunocytochemistry, proteomics\",\n      \"journal\": \"Blood advances\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO with ChIP-seq and RNA-seq plus in vivo xenograft, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"41925579\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ELL2 is a stoichiometrically limiting subunit of the Super Elongation Complex (SEC) that suppresses RNA polymerase II pausing; its C-terminal domain binds AFF4 (ELLBow) in an arch-shaped fold, and together they drive transcriptional elongation and stimulate altered RNA processing (proximal poly(A) site use and exon skipping) in plasma cells to generate secretory immunoglobulin heavy-chain mRNA; ELL2 stability is controlled by Siah1-mediated polyubiquitination (at K584/K599) and proteasomal degradation, which is counteracted by AFF4 binding or EAF2 binding, and by HCF1/2 blocking Siah1's substrate-binding domain; ELL2 also interacts physically with Ku70/Ku80 to facilitate non-homologous end joining DNA repair and with RB to suppress prostate cell proliferation, and it localizes to the nucleus via a bipartite NLS at residues 311–338.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ELL2 is an RNA polymerase II transcription elongation factor that stimulates productive elongation through an N-terminal elongation activation domain [#0] and operates as a stoichiometrically limiting subunit of the Super Elongation Complex (SEC), where its C-terminal domain adopts an arch-shaped, occludin-like fold that binds the ELLBow region of AFF4 across a concave surface required for SEC-driven proviral HIV-1 Tat transactivation [#7]. In plasma cells, ELL2 couples elongation to altered RNA processing: it promotes use of the promoter-proximal poly(A) site and exon skipping in immunoglobulin heavy-chain pre-mRNA by co-tracking with RNA polymerase II and the polyadenylation factor CstF-64, and ELL2 is required for their co-loading across the Igh locus [#1]. ELL2 thereby sets the secreted-versus-membrane transcript ratio, shapes a broad alternative splicing program during the B-cell to antibody-secreting-cell transition affecting cell-cycle and N-glycan biosynthesis genes, and enhances BCMA expression [#3, #14]. ELL2 promotes co-transcriptional deposition of H3K4 and H3K79 methylation and pTEFb-dependent Ser2 CTD phosphorylation at the IgH gene [#4], and B-cell-specific deletion in mice curtails humoral responses, depletes plasma cells, and collapses the secretory unfolded-protein-response program (XBP1, ATF6, BiP) [#5]. ELL2 abundance is governed by rapid proteasomal turnover: Siah1 polyubiquitinates ELL2 at K584/K599, while AFF4 binding, EAF2 binding, and HCF1/HCF2 blockade of the Siah1 substrate-binding domain all stabilize the protein and enhance SEC formation [#2, #11, #13]. Beyond transcription, ELL2 interacts with Ku70/Ku80 to facilitate their recruitment to double-strand breaks and non-homologous end joining [#8] and binds RB to suppress prostate epithelial proliferation, with prostate-specific deletion inducing prostatic intraepithelial neoplasia [#9, #10]. A hypomorphic Thr298Ala variant in the elongation domain associates with multiple myeloma risk and reduced immunoglobulin levels [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Established ELL2 as a bona fide RNA polymerase II elongation factor and localized its activity to an N-terminal elongation activation domain, defining its core biochemical function.\",\n      \"evidence\": \"In vitro transcription assays with truncation mutants\",\n      \"pmids\": [\"9108030\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define partner complexes (SEC) in which ELL2 acts in cells\", \"No structural basis for activity\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Connected ELL2's elongation activity to RNA processing fate, showing it directs proximal poly(A) site use and exon skipping in IgH pre-mRNA via co-loading of CstF-64 with RNA pol II.\",\n      \"evidence\": \"siRNA knockdown, ChIP, reporter constructs in plasma cells\",\n      \"pmids\": [\"19749764\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which ELL2 recruits CstF-64 not resolved\", \"Restricted to IgH locus initially\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Linked ELL2 to chromatin and CTD modification, showing its loss reduces H3K4/H3K79 methylation, Ser2 CTD phosphorylation, and MLL/Dot1L association at the IgH gene.\",\n      \"evidence\": \"siRNA knockdown and ChIP comparing B cells versus plasma cells\",\n      \"pmids\": [\"21832080\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus indirect recruitment of MLL/Dot1L unclear\", \"Single locus, single lab\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified Siah1 as the E3 ligase controlling ELL2 turnover and showed AFF4 binding protects ELL2, establishing degradation as a rheostat for SEC assembly.\",\n      \"evidence\": \"Reciprocal Co-IP, ubiquitination assays, proteasome inhibition, siRNA\",\n      \"pmids\": [\"22483617\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitinated lysines not yet mapped\", \"Upstream regulation of Siah1 in physiological settings unclear\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Quantified the breadth of ELL2-dependent transcript processing in plasma cells, showing it sets secreted/membrane Ig isoform ratios and affects ~12% of transcripts including BCMA.\",\n      \"evidence\": \"Lentiviral shRNA screen, RNA-Seq, isoform analysis\",\n      \"pmids\": [\"22991471\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct versus indirect target distinction incomplete\", \"Mechanism counteracting hnRNPLL not resolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrated ELL2 is required in vivo for plasma cell differentiation and the secretory program, tying its molecular activity to humoral immunity.\",\n      \"evidence\": \"CD19-Cre conditional knockout mice, immunization, flow cytometry, electron microscopy\",\n      \"pmids\": [\"25238757\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Causal chain from ELL2 loss to XBP1/ATF6 collapse not mechanistically dissected\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Revealed a viral co-option of ELL2, with HTLV-1 Tax transactivating the ELL2 promoter and forming a nuclear complex that synergistically activates the HTLV-1 LTR.\",\n      \"evidence\": \"qRT-PCR, promoter-luciferase, Co-IP, cell fractionation\",\n      \"pmids\": [\"25058508\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Interaction interface not yet mapped\", \"Single lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Provided human genetic evidence that a hypomorphic missense variant in the ELL2 elongation domain confers multiple myeloma risk and lowers immunoglobulin levels.\",\n      \"evidence\": \"Genome-wide association study with functional domain mapping\",\n      \"pmids\": [\"26007630\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct in vitro assay of variant elongation activity\", \"Causality at the cellular level inferred\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Solved the structural basis of ELL2 incorporation into the SEC, showing its C-terminal arch-shaped fold binds the AFF4 ELLBow, an interface required for HIV-1 Tat transactivation.\",\n      \"evidence\": \"2.0-Å X-ray crystallography, interface mutagenesis, Tat transactivation assay\",\n      \"pmids\": [\"28134250\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure limited to the C-terminal/AFF4 interface; full-length and pol II-bound architecture unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Uncovered a transcription-independent role for ELL2 in DNA repair, recruiting Ku70/Ku80 to double-strand breaks to support non-homologous end joining.\",\n      \"evidence\": \"Co-IP, NHEJ/HR assays, immunofluorescence at DSBs, siRNA knockdown and rescue\",\n      \"pmids\": [\"29179998\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether ELL2's elongation function is required for NHEJ unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified an RB-ELL2 interaction and a tumor-suppressive role in prostate cells, with co-loss enhancing proliferation, migration, and invasion.\",\n      \"evidence\": \"Co-IP, deletion mapping, siRNA, BrdU and invasion assays\",\n      \"pmids\": [\"28167296\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which RB binding suppresses proliferation unresolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Confirmed ELL2 as a prostate tumor suppressor in vivo, with prostate-specific deletion driving prostatic intraepithelial neoplasia.\",\n      \"evidence\": \"Conditional knockout mouse, histology, microarray, qPCR\",\n      \"pmids\": [\"28870994\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Link between transcriptional targets and PIN phenotype correlative\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Mapped the ELL2 degron, identifying K584/K599 as ubiquitination sites and EAF2 as a stabilizing partner, refining the post-translational control of ELL2 levels.\",\n      \"evidence\": \"MG132 treatment, site-directed mutagenesis, ubiquitination assays, Co-IP with EAF2\",\n      \"pmids\": [\"30009504\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether EAF2 and AFF4 stabilize via the same mechanism unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined the genome-wide scope of ELL2-dependent splicing in the antibody-secreting-cell transition, attributing ~55% of splicing changes to ELL2 and distinguishing direct from indirect effects.\",\n      \"evidence\": \"Splicing array, conditional ELL2 knockout B cells, ChIP\",\n      \"pmids\": [\"30297340\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic basis for indirect splicing changes unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Established HCF1/HCF2 as stabilizers of ELL2 by blocking the Siah1/2 substrate-binding domain, adding a layer to SEC abundance control relevant to HIV-1 transactivation.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, HIV-1 transactivation reporter, stability measurements\",\n      \"pmids\": [\"32479599\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological contexts triggering HCF-mediated stabilization unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Mapped the Tax-1/ELL2 interaction to the ELL2 R1 region containing the pol II-binding domain, distinguishing binding from functional transactivation enhancement.\",\n      \"evidence\": \"Co-IP, deletion mutagenesis, confocal microscopy, luciferase reporter\",\n      \"pmids\": [\"34948391\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Why R3 binds but does not enhance transactivation unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified a functional bipartite NLS at residues 311-338 within R1, explaining how ELL2 reaches the nucleus to perform its functions.\",\n      \"evidence\": \"Confocal imaging of truncation/NLS mutants, NLS-transfer fusion construct\",\n      \"pmids\": [\"39582094\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Import receptor not identified\", \"Regulation of nuclear import unknown\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Placed ELL2 in an IL-6/STAT3-driven autoregulatory transcriptional loop with POU2AF1 and IRF4 that sustains multiple myeloma growth and IL-6-dependent alternative splicing.\",\n      \"evidence\": \"ChIP-seq, RNA-seq, CRISPR knockout screen, xenograft, proteomics\",\n      \"pmids\": [\"41925579\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ELL2-POU2AF1 physical interaction not fully defined\", \"Mechanism linking the loop to specific MM splicing targets incomplete\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How ELL2's elongation activity is mechanistically coupled to its choice of poly(A) site and splice site, and whether its DNA-repair and tumor-suppressor roles depend on the same SEC machinery, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of full-length ELL2 in the pol II-engaged SEC\", \"Coupling logic between elongation and RNA processing decisions undefined\", \"Functional separability of transcription versus NHEJ/RB roles untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [7, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [16, 12]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [15]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 7]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [1, 3, 14]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [5, 3]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"complexes\": [\"Super Elongation Complex (SEC)\"],\n    \"partners\": [\"AFF4\", \"Siah1\", \"EAF2\", \"HCF1\", \"HCF2\", \"Ku70\", \"Ku80\", \"RB1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}