Affinage

POLE2

DNA polymerase epsilon subunit 2 · UniProt P56282

Length
527 aa
Mass
59.5 kDa
Annotated
2026-06-10
19 papers in source corpus 12 papers cited in narrative 12 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 3/3 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

POLE2 (DPE2) is the non-catalytic B-subunit of human DNA polymerase epsilon, where it tethers the catalytic POLE subunit to replication forks and functions as a general NPF-motif receptor through a shallow C-terminal pocket whose residues Y513, E520, and S522 coordinate diverse NPF-containing nuclear partners including WDHD1, DONSON, and TTF2 [PMID:bio_10.1101_2025.03.17.643635]. Through this motif-recognition activity, POLE2 acts as a hub coupling DNA replication to other replisome-associated processes: by binding the TTF2 N-terminal motif it recruits the TRAIP ubiquitin ligase to Polε at mitotic replication forks, enabling ubiquitylation of the CDC45-MCM-GINS (CMG) helicase that drives mitotic replisome disassembly and mitotic DNA synthesis [PMID:bio_10.1101_2024.12.01.626218]. Beyond replication, POLE2 recruits the Sin3/HDAC co-repressor to chromatin via an N-terminal interaction with SAP18, mediating trichostatin A-sensitive transcriptional repression at the fork (PMID:11872158). Its own expression is induced by mitogenic signals through E2F- and Sp1-dependent promoter elements (PMID:11433027). In cancer contexts POLE2 sits upstream of multiple proliferative and survival programs, stabilizing FOXM1 via AURKA (PMID:35039475) and supporting NRF2/GPX4-mediated ferroptosis resistance (PMID:38070189).

Mechanistic history

Synthesis pass · year-by-year structured walk · 6 steps
  1. 2001 High

    Established how POLE2 expression is controlled, showing it is a mitogen-responsive gene rather than constitutively expressed, linking its production to proliferative signals.

    Evidence Luciferase reporter, EMSA, and DNase I footprinting of the POLE2 promoter identifying Sp1 and overlapping E2F elements

    PMID:11433027

    Open questions at the time
    • Does not address the protein's biochemical function
    • In vivo relevance of individual E2F/Sp1 sites to physiological replication timing not tested
  2. 2002 Medium

    Identified an unexpected chromatin-modifying role for POLE2 beyond replication, showing it can couple the replication fork to transcriptional repression.

    Evidence Yeast two-hybrid screen with domain mapping (aa 85-250) plus reporter assays with trichostatin A inhibition in mouse

    PMID:11872158

    Open questions at the time
    • No demonstration at endogenous chromatin loci
    • Physiological consequence of HDAC recruitment during replication unresolved
    • Mouse system; human validation absent
  3. 2024 Medium

    Defined a direct biochemical mechanism by which POLE2 couples DNA Polε to replisome disassembly, answering how the TRAIP ligase is delivered to the CMG helicase at mitosis.

    Evidence Biochemical reconstitution, co-IP, TTF2 motif mutagenesis, and in vitro ubiquitylation (preprint)

    PMID:bio_10.1101_2024.12.01.626218

    Open questions at the time
    • Preprint, not peer-reviewed
    • Cellular requirement for the POLE2-TTF2 interaction in MiDAS not fully established
    • Structural basis of the POLE2 pocket-TTF2 interface not resolved at the time
  4. 2025 Medium

    Generalized POLE2's partner-binding role, showing the C-terminal pocket is a broad NPF-motif receptor rather than a dedicated single-partner interface, recasting POLE2 as a replication hub.

    Evidence Native holdup quantitative binding, residue mutagenesis (Y513/E520/S522), AlphaFold prediction, and proteome-scale affinity screens (preprint)

    PMID:bio_10.1101_2025.03.17.643635

    Open questions at the time
    • Preprint, not peer-reviewed
    • Functional consequences of WDHD1 and DONSON recruitment via this pocket not dissected
    • No experimental crystal/cryo-EM structure of the bound pocket
  5. 2023 Medium

    Connected POLE2 levels to a cancer survival program, placing it upstream of an anti-ferroptosis axis that sustains tumor cell proliferation.

    Evidence Lentiviral overexpression/knockdown with NRF2/GPX4 silencing rescue and ferroptosis assays in gastric cancer cells

    PMID:38070189

    Open questions at the time
    • Molecular mechanism linking the replication subunit to NRF2 induction unknown
    • Correlative epistasis rather than direct biochemical coupling
  6. 2022 Medium

    Linked POLE2 to transcription-factor stabilization in tumors, placing it upstream of AURKA-dependent FOXM1 control of proliferation.

    Evidence shRNA knockdown, ubiquitination assay, and FOXM1-knockdown rescue in glioblastoma

    PMID:35039475

    Open questions at the time
    • Direct physical link between POLE2 and AURKA/FOXM1 not shown
    • Whether effect reflects replication-stress signaling versus a moonlighting role unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unknown how POLE2's defined replisome/NPF-receptor biochemistry mechanistically produces the diverse oncogenic signaling outputs (FOXM1/AURKA, NRF2/GPX4, CD44/MDM2, Wnt/β-catenin, PI3K/AKT) reported in cancer models.
  • No direct biochemical bridge between the replication B-subunit function and the cytoplasmic/transcriptional signaling axes
  • Most cancer findings are single-lab knockdown/rescue without structural or interaction-level mechanism
  • Several pathway placements rest on Western blot epistasis or computational prediction only

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 2 GO:0140096 catalytic activity, acting on a protein 1
Localization
GO:0005634 nucleus 2
Pathway
R-HSA-69306 DNA Replication 2 R-HSA-74160 Gene expression (Transcription) 2
Partners
DONSONGINS4POLESAP18TRAIPTTF2WDHD1
Complex memberships
DNA polymerase epsilonSin3/HDAC co-repressor complex

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2002 The second largest subunit of mouse DNA polymerase epsilon (DPE2/POLE2) interacts with SAP18, a polypeptide associated with the Sin3 co-repressor protein. The interaction was identified by yeast two-hybrid screening and the N-terminal region of DPE2 (amino acids 85-250) was found to be responsible for binding SAP18. This interaction recruited Sin3/HDAC to repress transcription in reporter assays, an effect inhibited by trichostatin A, indicating that DPE2 can recruit histone deacetylase to modify chromatin structure at the replication fork. Yeast two-hybrid screening, reporter plasmid assay, trichostatin A inhibition Journal of biochemistry Medium 11872158
2001 The POLE2 promoter contains a 75 bp core region within exon 1 with a critical Sp1 element and two overlapping E2F elements required for full promoter activity and serum response. E2F1 and NF-1 binding sites reside downstream from the core promoter, and POLE2 is regulated by two E2F-pocket protein complexes (one associated with Sp1, one with NF-1), establishing E2F-mediated transcriptional induction of POLE2 in response to mitogenic signals. Luciferase reporter assay, EMSA (electrophoretic mobility shift assay), DNase I footprinting Nucleic acids research High 11433027
2022 POLE2 knockdown in glioblastoma cells promoted ubiquitination and reduced the stability of FOXM1 transcription factor through Aurora kinase A (AURKA). Knockdown of FOXM1 reversed the pro-malignant effects of POLE2, placing POLE2 upstream of AURKA-mediated FOXM1 stabilization in GBM. Loss-of-function (shRNA knockdown), ubiquitination assay, Western blot, rescue experiment with FOXM1 knockdown Cell death & disease Medium 35039475
2021 POLE2 knockdown in renal cell carcinoma identified stanniocalcin 1 (STC1) as a downstream gene of POLE2, with co-immunoprecipitation and microarray analysis showing POLE2 regulates STC1 to promote RCC progression; POLE2 knockdown also inhibited p-Akt, CCND1, MAPK9, and PIK3CA protein expression. Co-immunoprecipitation, microarray, Western blot, rescue experiment, xenograft model Frontiers in cell and developmental biology Medium 33644060
2023 HDAC10 deacetylates SP1; HDAC10 knockdown elevated SP1 acetylation and reduced SP1 binding to the POLE2 promoter, leading to reduced POLE2 expression. Overexpression of SP1 or POLE2 partially reversed the effects of HDAC10 deletion on NSCLC proliferation and ferroptosis, placing HDAC10 upstream of SP1-driven POLE2 transcription. ChIP (SP1 promoter binding), Western blot (acetylation), rescue overexpression, knockdown Pulmonary pharmacology & therapeutics Medium 37657752
2022 FOXM1 transcription factor binds the POLE2 promoter and drives POLE2 expression in lung adenocarcinoma; berberine downregulated FOXM1, which in turn reduced POLE2 expression, and this mechanism was confirmed by plasmid transfection rescue experiments. Plasmid transfection (FOXM1 overexpression/knockdown), quantitative RT-PCR, Western blotting, xenograft Frontiers in pharmacology Medium 35173608
2023 POLE2 overexpression in gastric cancer cells elevated NRF2 expression and activity, which subsequently activated GPX4 to prevent lipid peroxidation and ferroptosis; silencing NRF2 or GPX4 prevented POLE2-mediated induction of proliferation and inhibition of ferroptosis, placing POLE2 upstream of the NRF2/GPX4 anti-ferroptosis axis. Lentiviral overexpression/knockdown, ferroptosis assay, Western blot, rescue experiment (NRF2/GPX4 silencing) Journal of cellular and molecular medicine Medium 38070189
2024 POLE2 promotes CD44 protein stability in osteosarcoma cells by reducing MDM2-mediated ubiquitination and degradation of CD44; POLE2 knockdown increased CD44 ubiquitination, and CD44 knockdown inhibited the tumor-promoting effects of POLE2 overexpression, with downstream activation of Rac signaling. Ubiquitination assay, Western blot, knockdown/overexpression rescue, xenograft Cell death discovery Medium 38627379
2024 POLE2 silencing in colorectal carcinoma cells inactivated the Wnt/β-catenin signaling pathway; activation of Wnt/β-catenin reversed the effects of POLE2 knockdown on CRC cell proliferation, migration and invasion, placing POLE2 upstream of Wnt/β-catenin signaling. Western blot (pathway proteins), rescue activation of Wnt pathway, knockdown, xenograft Cancer biology & therapy Low 39155507
2025 POLE2 functions as a general NPF-motif receptor through a shallow binding pocket near its C-terminus, with residues Y513, E520, and S522 critical for motif coordination. POLE2 binds diverse NPF-containing nuclear proteins (including WDHD1, DONSON, TTF2) with micromolar affinities; motif mutations abolished binding in cell extracts. This identifies POLE2 as a hub linking DNA replication with other processes via broad NPF-motif recognition beyond its primary role of tethering catalytic POLE to replication forks. Native holdup assay (quantitative binding), mutational analysis, AlphaFold structural prediction, proteome-scale affinity screens, cell extract binding assay bioRxivpreprint Medium bio_10.1101_2025.03.17.643635
2024 TTF2 binds directly to POLE2 via a specific TTF2 amino-terminal motif that recognizes POLE2, coupling the TRAIP ubiquitin ligase to DNA Polymerase ε at mitotic replication forks. This complex enables TRAIP to ubiquitylate the CDC45-MCM-GINS (CMG) helicase, triggering replisome disassembly and Mitotic DNA Synthesis (MiDAS); TTF2 also contains tandem zinc fingers that recognize phosphorylated TRAIP. Biochemical reconstitution, co-immunoprecipitation, mutational analysis (TTF2 motif), in vitro ubiquitylation assay bioRxivpreprint Medium bio_10.1101_2024.12.01.626218
2025 GINS4 physically binds to POLE2 (predicted by STRING and HDOCK databases, assessed by immunofluorescence), and GINS4 silencing inhibited POLE2 expression; POLE2 overexpression reversed GINS4 knockdown effects on proliferation, cell cycle, and ferroptosis by restoring PI3K/AKT signaling activation. Protein-protein interaction prediction (STRING/HDOCK), immunofluorescence, Western blot, rescue overexpression, xenograft Cellular signalling Low 40081544

Source papers

Stage 0 corpus · 19 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2018 Knockdown of POLE2 expression suppresses lung adenocarcinoma cell malignant phenotypes in vitro. Oncology reports 28 30132567
2022 POLE2 facilitates the malignant phenotypes of glioblastoma through promoting AURKA-mediated stabilization of FOXM1. Cell death & disease 20 35039475
2020 POLE2 knockdown reduce tumorigenesis in esophageal squamous cells. Cancer cell international 20 32831648
2015 In silico analysis of family GH77 with focus on amylomaltases from borreliae and disproportionating enzymes DPE2 from plants and bacteria. Biochimica et biophysica acta 18 26006747
2002 The second largest subunit of mouse DNA polymerase epsilon, DPE2, interacts with SAP18 and recruits the Sin3 co-repressor protein to DNA. Journal of biochemistry 16 11872158
2001 E2F mediates induction of the Sp1-controlled promoter of the human DNA polymerase epsilon B-subunit gene POLE2. Nucleic acids research 16 11433027
2023 Knockdown of HDAC10 inhibits POLE2-mediated DNA damage repair in NSCLC cells by increasing SP1 acetylation levels. Pulmonary pharmacology & therapeutics 12 37657752
2021 Targeting POLE2 Creates a Novel Vulnerability in Renal Cell Carcinoma via Modulating Stanniocalcin 1. Frontiers in cell and developmental biology 12 33644060
2022 Berberine Inhibits FOXM1 Dependent Transcriptional Regulation of POLE2 and Interferes With the Survival of Lung Adenocarcinoma. Frontiers in pharmacology 10 35173608
2023 Inhibition of ferroptosis by POLE2 in gastric cancer cells involves the activation of NRF2/GPX4 pathway. Journal of cellular and molecular medicine 9 38070189
2017 Photometric assay of maltose and maltose-forming enzyme activity by using 4-alpha-glucanotransferase (DPE2) from higher plants. Analytical biochemistry 7 28576440
2024 POLE2 promotes osteosarcoma progression by enhancing the stability of CD44. Cell death discovery 5 38627379
2024 POLE2 silencing inhibits the progression of colorectal carcinoma cells via wnt signaling axis. Cancer biology & therapy 5 39155507
2023 POLE2 Regulates Apoptosis of Oral Squamous Cell Carcinoma Cells through the PI3K/AKT Signaling Pathway. Current medical science 5 38079056
2022 Phosphorylation of DPE2 at S786 partially regulates starch degradation. Plant physiology and biochemistry : PPB 5 36335878
2023 POLE2 knockdown suppresses lymphoma progression via downregulating Wnt/β-catenin signaling pathway. Molecular and cellular biochemistry 4 37097331
2025 GINS4 silencing mediates hepatocellular cancer cell proliferation, cycle and ferroptosis through POLE2. Cellular signalling 3 40081544
2023 Silencing POLE2 promotes apoptosis and inhibits proliferation of oral squamous cell carcinomas by inhibiting PI3K/AKT signaling pathway. Medical oncology (Northwood, London, England) 1 37733085
2026 Role of POLE2/GINS1-mediated AKT/mTOR pathway in RCC autophagy, proliferation, and metastasis: evidences from bioinformatic, clinical, and experimental data. Apoptosis : an international journal on programmed cell death 0 41893924

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