Affinage

ELL2

RNA polymerase II elongation factor ELL2 · UniProt O00472

Length
640 aa
Mass
72.3 kDa
Annotated
2026-06-09
26 papers in source corpus 18 papers cited in narrative 18 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

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).

Mechanistic history

Synthesis pass · year-by-year structured walk · 18 steps
  1. 1997 High

    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

    PMID:9108030

    Open questions at the time
    • Did not define partner complexes (SEC) in which ELL2 acts in cells
    • No structural basis for activity
  2. 2009 High

    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

    PMID:19749764

    Open questions at the time
    • Mechanism by which ELL2 recruits CstF-64 not resolved
    • Restricted to IgH locus initially
  3. 2011 Medium

    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

    PMID:21832080

    Open questions at the time
    • Direct versus indirect recruitment of MLL/Dot1L unclear
    • Single locus, single lab
  4. 2012 High

    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

    PMID:22483617

    Open questions at the time
    • Ubiquitinated lysines not yet mapped
    • Upstream regulation of Siah1 in physiological settings unclear
  5. 2012 High

    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

    PMID:22991471

    Open questions at the time
    • Direct versus indirect target distinction incomplete
    • Mechanism counteracting hnRNPLL not resolved
  6. 2014 High

    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

    PMID:25238757

    Open questions at the time
    • Causal chain from ELL2 loss to XBP1/ATF6 collapse not mechanistically dissected
  7. 2014 Medium

    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

    PMID:25058508

    Open questions at the time
    • Interaction interface not yet mapped
    • Single lab
  8. 2015 Medium

    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

    PMID:26007630

    Open questions at the time
    • No direct in vitro assay of variant elongation activity
    • Causality at the cellular level inferred
  9. 2017 High

    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

    PMID:28134250

    Open questions at the time
    • Structure limited to the C-terminal/AFF4 interface; full-length and pol II-bound architecture unknown
  10. 2017 Medium

    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

    PMID:29179998

    Open questions at the time
    • Whether ELL2's elongation function is required for NHEJ unclear
    • Single lab
  11. 2017 Medium

    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

    PMID:28167296

    Open questions at the time
    • Mechanism by which RB binding suppresses proliferation unresolved
  12. 2017 Medium

    Confirmed ELL2 as a prostate tumor suppressor in vivo, with prostate-specific deletion driving prostatic intraepithelial neoplasia.

    Evidence Conditional knockout mouse, histology, microarray, qPCR

    PMID:28870994

    Open questions at the time
    • Link between transcriptional targets and PIN phenotype correlative
  13. 2018 Medium

    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

    PMID:30009504

    Open questions at the time
    • Whether EAF2 and AFF4 stabilize via the same mechanism unclear
  14. 2018 Medium

    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

    PMID:30297340

    Open questions at the time
    • Mechanistic basis for indirect splicing changes unknown
  15. 2020 Medium

    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

    PMID:32479599

    Open questions at the time
    • Physiological contexts triggering HCF-mediated stabilization unclear
  16. 2021 Medium

    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

    PMID:34948391

    Open questions at the time
    • Why R3 binds but does not enhance transactivation unresolved
  17. 2024 Medium

    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

    PMID:39582094

    Open questions at the time
    • Import receptor not identified
    • Regulation of nuclear import unknown
  18. 2026 Medium

    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

    PMID:41925579

    Open questions at the time
    • Direct ELL2-POU2AF1 physical interaction not fully defined
    • Mechanism linking the loop to specific MM splicing targets incomplete

Open questions

Synthesis pass · forward-looking unresolved questions
  • 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.
  • 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

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 2 GO:0098772 molecular function regulator activity 2 GO:0140110 transcription regulator activity 2
Localization
GO:0005634 nucleus 2 GO:0005654 nucleoplasm 1
Pathway
R-HSA-8953854 Metabolism of RNA 3 R-HSA-168256 Immune System 2 R-HSA-74160 Gene expression (Transcription) 2 R-HSA-73894 DNA Repair 1
Partners
AFF4EAF2HCF1HCF2KU70KU80RB1SIAH1
Complex memberships
Super Elongation Complex (SEC)

Evidence

Reading pass · 18 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1997 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). In vitro transcription assays, structure-function studies with truncation mutants Proceedings of the National Academy of Sciences of the United States of America High 9108030
2009 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. siRNA knockdown, chromatin immunoprecipitation (ChIP), reporter constructs, hnRNP F transfection Nature immunology High 19749764
2012 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. Co-immunoprecipitation, ubiquitination assays, proteasome inhibitor experiments, siRNA knockdown Molecular cell High 22483617
2012 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. Lentiviral shRNA screen, RNA-Seq, transfection-based isoform analysis Proceedings of the National Academy of Sciences of the United States of America High 22991471
2011 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. siRNA knockdown, chromatin immunoprecipitation (ChIP), comparison of B cells versus plasma cells The Journal of biological chemistry Medium 21832080
2014 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. Conditional knockout mouse model (Cre/loxP with CD19-Cre), ex vivo stimulation, immunization, flow cytometry, qPCR, electron microscopy Journal of immunology (Baltimore, Md. : 1950) High 25238757
2015 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. Genome-wide association study, functional domain mapping (missense variant in known elongation domain) Nature communications Medium 26007630
2017 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. X-ray crystallography, mutagenesis of binding interface, HIV-1 Tat transactivation assay Nature communications High 28134250
2017 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. Co-immunoprecipitation, NHEJ/HR repair assays, immunofluorescence at DSB sites, siRNA knockdown and rescue Cancer letters Medium 29179998
2017 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. Co-immunoprecipitation, deletion mutagenesis, siRNA knockdown, BrdU incorporation, Transwell/invasion assays Neoplasia (New York, N.Y.) Medium 28167296
2017 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. Conditional knockout mouse model, histology, microarray, qPCR The Journal of endocrinology Medium 28870994
2018 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. Proteasome inhibitor (MG132) treatment, deletion and site-directed mutagenesis, ubiquitination assays, co-immunoprecipitation with EAF2 The Prostate Medium 30009504
2014 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. qRT-PCR, promoter-luciferase assay, co-immunoprecipitation, cell fractionation Virology Medium 25058508
2020 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. Co-immunoprecipitation, ubiquitination assays, HIV-1 transactivation reporter assays, ELL2 stability measurements Nucleic acids research Medium 32479599
2018 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. Splicing array, conditional ELL2 knockout B cells, LPS stimulation ex vivo, ChIP Journal of immunology (Baltimore, Md. : 1950) Medium 30297340
2021 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. Co-immunoprecipitation, deletion mutagenesis, confocal microscopy, luciferase reporter assay International journal of molecular sciences Medium 34948391
2024 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. Confocal laser scanning microscopy of truncation mutants, site-directed mutagenesis of NLS residues, NLS-mapping fusion construct Cell biochemistry and function Medium 39582094
2026 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. ChIP-seq, RNA-seq, CRISPR knockout screening, xenograft model, immunocytochemistry, proteomics Blood advances Medium 41925579

Source papers

Stage 0 corpus · 26 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2017 Long noncoding RNA MRCCAT1 promotes metastasis of clear cell renal cell carcinoma via inhibiting NPR3 and activating p38-MAPK signaling. Molecular cancer 186 28659173
1997 ELL2, a new member of an ELL family of RNA polymerase II elongation factors. Proceedings of the National Academy of Sciences of the United States of America 112 9108030
2009 Transcription elongation factor ELL2 directs immunoglobulin secretion in plasma cells by stimulating altered RNA processing. Nature immunology 110 19749764
2015 Variants in ELL2 influencing immunoglobulin levels associate with multiple myeloma. Nature communications 73 26007630
2012 The ubiquitin ligase Siah1 controls ELL2 stability and formation of super elongation complexes to modulate gene transcription. Molecular cell 57 22483617
2014 Transcription elongation factor ELL2 drives Ig secretory-specific mRNA production and the unfolded protein response. Journal of immunology (Baltimore, Md. : 1950) 42 25238757
2012 Heterogeneous nuclear ribonucleoprotein L-like (hnRNPLL) and elongation factor, RNA polymerase II, 2 (ELL2) are regulators of mRNA processing in plasma cells. Proceedings of the National Academy of Sciences of the United States of America 35 22991471
2017 Structural basis for ELL2 and AFF4 activation of HIV-1 proviral transcription. Nature communications 32 28134250
2018 RNA Splicing in the Transition from B Cells to Antibody-Secreting Cells: The Influences of ELL2, Small Nuclear RNA, and Endoplasmic Reticulum Stress. Journal of immunology (Baltimore, Md. : 1950) 19 30297340
2017 Genetic Predisposition to Multiple Myeloma at 5q15 Is Mediated by an ELL2 Enhancer Polymorphism. Cell reports 18 28903037
2020 Host cell factors stimulate HIV-1 transcription by antagonizing substrate-binding function of Siah1 ubiquitin ligase to stabilize transcription elongation factor ELL2. Nucleic acids research 17 32479599
2017 ELL2 regulates DNA non-homologous end joining (NHEJ) repair in prostate cancer cells. Cancer letters 17 29179998
2011 The eleven-nineteen lysine-rich leukemia gene (ELL2) influences the histone H3 protein modifications accompanying the shift to secretory immunoglobulin heavy chain mRNA production. The Journal of biological chemistry 17 21832080
2017 Physical and Functional Interactions between ELL2 and RB in the Suppression of Prostate Cancer Cell Proliferation, Migration, and Invasion. Neoplasia (New York, N.Y.) 16 28167296
2017 Selective expression of the transcription elongation factor ELL3 in B cells prior to ELL2 drives proliferation and survival. Molecular immunology 13 28858629
2014 The transcription elongation factor ELL2 is specifically upregulated in HTLV-1-infected T-cells and is dependent on the viral oncoprotein Tax. Virology 13 25058508
2017 Conditional deletion of ELL2 induces murine prostate intraepithelial neoplasia. The Journal of endocrinology 11 28870994
2020 ELL2 Is Required for the Growth and Survival of AR-Negative Prostate Cancer Cells. Cancer management and research 8 32606936
2019 Anti-apoptotic factor Birc3 is up-regulated by ELL2 knockdown and stimulates proliferation in LNCaP cells. American journal of clinical and experimental urology 8 31511829
2019 ELL2 Influences Transcription Elongation, Splicing, Ig Secretion and Growth. Journal of mucosal immunology research 7 31930204
2018 Regulation of ELL2 stability and polyubiquitination by EAF2 in prostate cancer cells. The Prostate 7 30009504
2018 Concurrent EAF2 and ELL2 loss phenocopies individual EAF2 or ELL2 loss in prostate cancer cells and murine prostate. American journal of clinical and experimental urology 6 30697579
2021 Characterizing the Interaction between the HTLV-1 Transactivator Tax-1 with Transcription Elongation Factor ELL2 and Its Impact on Viral Transactivation. International journal of molecular sciences 2 34948391
2019 ELL2 Is Downregulated and Associated with Galactose-Deficient IgA1 in IgA Nephropathy. Disease markers 1 31275443
2026 IL-6-driven POU2AF1 and ELL2 are key regulators of multiple myeloma-distinct transcriptional and splicing programs. Blood advances 0 41925579
2024 Identification of a Nuclear Localization Signal (NLS) in Human Transcription Elongation Factor ELL2. Cell biochemistry and function 0 39582094

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