Affinage

EAPP

E2F-associated phosphoprotein · UniProt Q56P03

Length
285 aa
Mass
32.8 kDa
Annotated
2026-06-09
51 papers in source corpus 9 papers cited in narrative 10 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

EAPP (E2F-associated phosphoprotein) is a nuclear phosphoprotein that modulates transcriptional programs governing cell-cycle progression and the response to DNA damage (PMID:15716352, PMID:21258403). Identified through its selective physical interaction with the activating E2F family members E2F-1, -2, and -3 but not E2F-4, EAPP is present throughout the cell cycle, disappears during mitosis, and shifts the population toward S-phase upon overexpression while knockdown reduces S-phase entry (PMID:15716352). Its effect on E2F output is promoter-context-dependent: it augments E2F-1-driven activation of artificial E2F and thymidine kinase promoters yet represses E2F-1-driven activation of the p14ARF promoter (PMID:15716352). Beyond E2F, EAPP acts directly at several promoters: it binds the p21 promoter and stimulates p21 expression independently of p53 — and is required for assembly of the transcription initiation complex there — driving G1 arrest and resistance to DNA damage- or E2F1-induced apoptosis in a p21-dependent manner (PMID:21258403); it represses MAO B transcription by competing with Sp1 for occupancy of Sp1 sites in the core promoter (PMID:20980443); and it activates the MDR1/ABCB1 promoter by an E2F1-independent, pRb-insensitive mechanism, raising P-glycoprotein levels (PMID:23542036). EAPP also modulates the DNA damage checkpoint by promoting dephosphorylation and inactivation of Chk2 (PMID:21572256). EAPP expression is itself controlled at a TATA-less promoter bearing functional Sp1, Sp3, and Egr-1 sites, with Sp1 and Egr-1 activating and Sp3 repressing it (PMID:18588995).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2005 High

    Established EAPP as a physical partner of activating E2Fs and a regulator of cell-cycle progression, defining its core identity as an E2F-associated nuclear phosphoprotein.

    Evidence Yeast two-hybrid screen, cell fractionation/imaging, E2F-dependent reporter assays, and RNAi with cell-cycle analysis

    PMID:15716352

    Open questions at the time
    • Interaction surface/domain on EAPP and E2F not mapped
    • No structural model of the EAPP-E2F complex
    • Mechanism by which EAPP disappears during mitosis unresolved
  2. 2005 Medium

    Showed that EAPP's effect on E2F-1 transcription is not uniformly activating but depends on promoter context, distinguishing it from a simple coactivator.

    Evidence Transfection reporter assays comparing artificial E2F, thymidine kinase, and p14ARF promoters

    PMID:15716352

    Open questions at the time
    • Single method (reporter assays) without endogenous gene readout
    • Basis of context-dependent switch between activation and repression unknown
  3. 2005 Low

    Mapped EAPP (C14ORF11/BM036) to the HPE8 holoprosencephaly locus and documented fetal brain expression, raising it as a developmental candidate gene.

    Evidence BAC contig chromosome walking, fetal brain expression, and cellular localization of candidate genes

    PMID:15820313

    Open questions at the time
    • No direct functional or mutational evidence linking EAPP to holoprosencephaly
    • Positional candidacy only, not causation
  4. 2008 High

    Defined how EAPP itself is transcriptionally controlled, explaining its elevated levels in transformed cells via reduced Sp3 repression.

    Evidence EMSA, supershift/competition assays, ChIP, and luciferase reporter assays with promoter truncations

    PMID:18588995

    Open questions at the time
    • Whether Sp3 loss is sufficient to drive transformation phenotypes not tested
    • Upstream signals controlling Sp1/Sp3/Egr-1 balance at the EAPP promoter unknown
  5. 2010 High

    Identified a direct DNA-level mechanism whereby EAPP represses target genes by competing with Sp1 for promoter occupancy, demonstrated at the MAO B promoter.

    Evidence Yeast one-hybrid with Sp1 motifs, EMSA competition, ChIP, and reporter assays with dexamethasone modulation

    PMID:20980443

    Open questions at the time
    • Whether EAPP binds Sp1 sites directly or via a partner not fully resolved
    • Generality of Sp1-competition mechanism beyond MAO B untested
  6. 2011 High

    Established EAPP as a p53-independent activator of p21 that promotes G1 arrest and apoptosis resistance, placing it in the DNA damage response.

    Evidence Overexpression/RNAi in U2OS, flow cytometry, ChIP at the p21 promoter, reporter assays, and epistasis with p21

    PMID:21258403

    Open questions at the time
    • How EAPP recruits/assembles the initiation complex at p21 not mechanistically detailed
    • Reconciliation between S-phase promotion (2005) and G1 arrest (2011) phenotypes unresolved
  7. 2011 Medium

    Linked EAPP to checkpoint control by showing it promotes dephosphorylation and inactivation of Chk2.

    Evidence Overexpression/knockdown, phospho-Chk2 western blotting, and co-immunoprecipitation/binding assays

    PMID:21572256

    Open questions at the time
    • Phosphatase mediating Chk2 dephosphorylation not identified; limited orthogonal validation
    • Direct vs indirect EAPP-Chk2 interaction unconfirmed
  8. 2013 Medium

    Showed EAPP activates the MDR1/ABCB1 promoter through a mechanism distinct from E2F1, implicating it in multidrug resistance.

    Evidence MDR1 promoter reporter assays, pRb epistasis test, and PGP western blotting

    PMID:23542036

    Open questions at the time
    • DNA element and cofactors mediating EAPP activation of MDR1 not defined
    • Effect on endogenous drug resistance in cells not demonstrated
  9. 2015 Medium

    Extended EAPP function to injury and dual cell-type contexts, associating it with neuronal apoptosis and astrocyte proliferation in vivo.

    Evidence Rat spinal cord injury model with IHC/western, caspase-3/PCNA co-localization, and in vitro siRNA with proliferation/migration assays

    PMID:25704466

    Open questions at the time
    • Molecular link between EAPP and caspase-3/CDK4/cyclin D1 not mechanistically established
    • Abstract-level description limits mechanistic depth
  10. 2016 Medium

    Placed EAPP upstream of a stress-response gene network in vivo and confirmed cis-genetic control of its own expression.

    Evidence eQTL mapping, qPCR/IHC in stress-exposed mice, and siRNA knockdown with downstream target profiling (including Maob)

    PMID:26802973

    Open questions at the time
    • Direct vs indirect regulation of the named downstream genes not distinguished
    • Mechanistic pathway placement is correlative

Open questions

Synthesis pass · forward-looking unresolved questions
  • How EAPP integrates its opposing activities — promoting S-phase yet driving p21-dependent G1 arrest, and switching between transcriptional activation and repression at different promoters — into a unified mechanism remains unresolved.
  • No structural or biochemical basis for the activation/repression switch
  • No identification of the phosphatase or cofactors mediating Chk2 dephosphorylation
  • Physiological role and any disease causation not established

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140110 transcription regulator activity 4 GO:0003677 DNA binding 2
Localization
GO:0005634 nucleus 1
Pathway
R-HSA-74160 Gene expression (Transcription) 4 R-HSA-1640170 Cell Cycle 2 R-HSA-73894 DNA Repair 2
Partners
CDCA7LCHEK2E2F1E2F2E2F3SP1

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2005 EAPP (E2F-associated phosphoprotein) is a nuclear phosphoprotein identified via yeast two-hybrid screen that physically interacts with E2F-1, E2F-2, and E2F-3, but not E2F-4. EAPP is localized in the nucleus, is present throughout the cell cycle but disappears during mitosis, and its overexpression increases the fraction of cells in S-phase while RNAi-mediated knockdown reduces S-phase fraction. Yeast two-hybrid screen, nuclear localization confirmed by cell fractionation/imaging, transfection reporter assays with E2F-dependent and thymidine kinase promoters, RNAi knockdown with cell cycle analysis Molecular biology of the cell High 15716352
2005 EAPP increases E2F-1-driven transcriptional activation from an artificial E2F-dependent promoter and the murine thymidine kinase promoter, but represses E2F-1-driven activation of the p14ARF promoter, demonstrating promoter-context-dependent modulation of E2F transcriptional output. Transfection reporter assays with E2F-dependent artificial promoter and endogenous promoter constructs Molecular biology of the cell Medium 15716352
2008 The EAPP gene promoter is TATA-less and contains functional binding sites for Sp1, Sp3, and Egr-1; Sp1 and Egr-1 activate the EAPP promoter while Sp3 represses it, and reduced Sp3 activity can account for elevated EAPP levels in transformed cells. Electrophoretic mobility shift assay (EMSA), supershift and competition assays, chromatin immunoprecipitation (ChIP), luciferase reporter assays with promoter truncations The international journal of biochemistry & cell biology High 18588995
2010 EAPP and R1 (RAM2/CDCA7L/JPO2) function as transcriptional repressors of the MAO B gene by competing with Sp1 for binding to Sp1 sites in the MAO B core promoter; in response to dexamethasone, EAPP and R1 occupancy at the MAO B promoter decreases while Sp1 occupancy increases, enabling glucocorticoid activation of MAO B. Yeast one-hybrid screen (using Sp1-binding motifs as bait), EMSA (competition assay for Sp1 site binding), chromatin immunoprecipitation (ChIP) in cells, transfection reporter assays Molecular pharmacology High 20980443
2011 EAPP overexpression in U2OS cells results in G1 arrest and heightened resistance to DNA damage- or E2F1-induced apoptosis in a p21-dependent manner. EAPP levels are upregulated after DNA damage and in confluent cells. EAPP binds directly to the p21 promoter and stimulates p21 expression independently of p53, and appears required for assembly of the transcription initiation complex at the p21 promoter. RNAi knockdown of EAPP increases sensitivity to DNA damage and causes apoptosis even without stress. Overexpression and RNAi knockdown in U2OS cells, flow cytometry for cell cycle and apoptosis, chromatin immunoprecipitation (ChIP) at p21 promoter, p21 promoter reporter assays, epistasis with p21 Oncogene High 21258403
2011 EAPP regulates the phosphorylation status and activity of Chk2; EAPP binding appears to trigger dephosphorylation of phospho-Chk2, resulting in its inactivation, thereby modulating the DNA damage checkpoint response. Overexpression and knockdown experiments, western blotting for phospho-Chk2, co-immunoprecipitation/binding assays Cell cycle (Georgetown, Tex.) Medium 21572256
2013 EAPP stimulates the MDR1 (ABCB1) promoter resulting in elevated P-glycoprotein (PGP) levels. This activation is independent of E2F1 and is not blocked by co-expression of pRb (which does inhibit E2F1-dependent MDR1 promoter activation), indicating a distinct mechanism for EAPP-driven MDR1 regulation. Transfection reporter assays with MDR1 promoter, co-expression of pRb as epistasis test, western blotting for PGP protein levels FEBS letters Medium 23542036
2015 In a rat spinal cord injury model, EAPP protein levels increase and peak at day 3 post-injury in neurons and astrocytes. EAPP co-localizes with active caspase-3 in neurons (suggesting a role in neuronal apoptosis) and with PCNA in astrocytes. In vitro siRNA knockdown of EAPP in astrocytes inhibits proliferation, migration, and CDK4/cyclin D1 expression, while EAPP knockdown in neurons reduces apoptosis and cell cycle protein levels. Rat SCI model with immunohistochemistry and western blotting, co-localization with caspase-3 and PCNA, siRNA knockdown in vitro with proliferation, migration, and western blot assays Journal of cellular biochemistry Medium 25704466
2016 In mouse hypothalamus, Eapp expression is controlled by a cis-acting quantitative trait locus (cis-eQTL). siRNA knockdown of Eapp alters expression of downstream targets Sphk2, Nosip, Mmp9, Npy, Npy5r, and Maob, placing Eapp upstream of these genes in a stress-response gene network. Western blotting, qPCR, immunohistochemistry in stress-exposed mice, eQTL mapping, siRNA knockdown with expression profiling of downstream targets Gene Medium 26802973
2005 EAPP (referred to as C14ORF11 / BM036) maps to the HPE8 locus on chromosome 14q13 and is expressed in human fetal brain, suggesting candidacy for holoprosencephaly; protein cellular localization was determined experimentally as part of candidate gene characterization. BAC contig chromosome walking, annotation of minimal critical region, expression analysis in human fetal brain, protein cellular localization assays for candidate genes Genomics Low 15820313

Source papers

Stage 0 corpus · 51 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2005 Osteoblast elastic modulus measured by atomic force microscopy is substrate dependent. Annals of biomedical engineering 110 16060537
2016 Cooperative Effect of miR-141-3p and miR-145-5p in the Regulation of Targets in Clear Cell Renal Cell Carcinoma. PloS one 69 27336447
2005 Protein interaction quantified in vivo by spectrally resolved fluorescence resonance energy transfer. The Biochemical journal 64 15352875
2001 An electrochemical immunosensor for milk progesterone using a continuous flow system. Biosensors & bioelectronics 52 11679249
2013 FRET spectrometry: a new tool for the determination of protein quaternary structure in living cells. Biophysical journal 48 24209838
2004 Stretch-induced nitric oxide modulates mechanical properties of skeletal muscle cells. American journal of physiology. Cell physiology 43 15044149
2010 Transcription factor E2F-associated phosphoprotein (EAPP), RAM2/CDCA7L/JPO2 (R1), and simian virus 40 promoter factor 1 (Sp1) cooperatively regulate glucocorticoid activation of monoamine oxidase B. Molecular pharmacology 37 20980443
2000 Detection of a urinary biomaker for oxidative DNA damage 8-hydroxydeoxyguanosine by capillary electrophoresis with electrochemical detection. Electrophoresis 37 10879970
2010 Tuning the mechanical properties of bioreducible multilayer films for improved cell adhesion and transfection activity. Biomaterials 35 20580430
2010 Construction of a star-shaped copolymer as a vector for FGF receptor-mediated gene delivery in vitro and in vivo. Biomacromolecules 35 20704346
2004 Structure of a novel c7-type three-heme cytochrome domain from a multidomain cytochrome c polymer. Protein science : a publication of the Protein Society 35 15133162
1975 Solvent accessibility in folded proteins. Studies of hydrogen exchange in trypsin. The Journal of biological chemistry 35 234428
2005 Defining a holoprosencephaly locus on human chromosome 14q13 and characterization of potential candidate genes. Genomics 32 15820313
1991 Enzyme-modified organic conducting salt microelectrode. Analytical chemistry 32 1789455
2017 Endothelium-specific amyloid precursor protein deficiency causes endothelial dysfunction in cerebral arteries. Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 25 28959912
2013 Regulation of the MDR1 promoter by E2F1 and EAPP. FEBS letters 25 23542036
2009 A stable and selective electrochemical biosensor for the liver enzyme alanine aminotransferase (ALT). Biosensors & bioelectronics 25 19356918
2012 14q13.1-21.1 deletion encompassing the HPE8 locus in an adolescent with intellectual disability and bilateral microphthalmia, but without holoprosencephaly. American journal of medical genetics. Part A 21 22581785
2008 The ethanol extract from Artemisia princeps Pampanini induces p53-mediated G1 phase arrest in A172 human neuroblastoma cells. Journal of medicinal food 20 18598164
2005 EAPP, a novel E2F binding protein that modulates E2F-dependent transcription. Molecular biology of the cell 20 15716352
1999 Characterization of the bile acid sensitive methotrexate carrier of rat liver cells. Naunyn-Schmiedeberg's archives of pharmacology 19 10498292
2007 Efalizumab-associated papular psoriasis. Archives of dermatology 18 17638735
2001 An assay for the enzyme N-acetyl-beta-D-glucosaminidase (NAGase) based on electrochemical detection using screen-printed carbon electrodes (SPCEs). The Analyst 18 11763057
2011 EAPP: gatekeeper at the crossroad of apoptosis and p21-mediated cell-cycle arrest. Oncogene 15 21258403
2019 Effect of suboptimal temperature on the regulation of endogenous antigen presentation in a rainbow trout hypodermal fibroblast cell line. Developmental and comparative immunology 14 31254564
2003 Amperometric sensing at high temperature with a "wired" thermostable glucose-6-phosphate dehydrogenase from Aquifex aeolicus. Analytical chemistry 14 14572059
2022 Current status and challenges of drug development for hormonal treatment of endometriosis: a systematic review of randomized control trials. Gynecological endocrinology : the official journal of the International Society of Gynecological Endocrinology 13 35971323
2009 In vivo associations of Escherichia coli NarJ with a peptide of the first 50 residues of nitrate reductase catalytic subunit NarG. Canadian journal of microbiology 13 19295650
2006 Crystal structures of human IPP isomerase: new insights into the catalytic mechanism. Journal of molecular biology 12 17137593
2021 Syk-Targeted, a New 3-Arylbenzofuran Derivative EAPP-2 Blocks Airway Inflammation of Asthma-COPD Overlap in vivo and in vitro. Journal of inflammation research 11 34079326
2015 Applied potentials regulate recovery of residual hydrogen from acid-rich effluents: Influence of biocathodic buffer capacity over process performance. Bioresource technology 10 25736904
2022 Simultaneous electrochemical immunosensing of relevant cytokines to diagnose and track cancer and autoimmune diseases. Bioelectrochemistry (Amsterdam, Netherlands) 9 35594731
2019 Regulation of endogenous antigen presentation in response to suboptimal temperatures in a walleye skin fibroblast cell line. Fish & shellfish immunology 9 31740400
2012 Optimization of protein solution by a novel experimental design method using thermodynamic properties. Archives of pharmacal research 9 23054718
2010 A screen-printed microband glucose biosensor system for real-time monitoring of toxicity in cell culture. Biosensors & bioelectronics 9 21081270
2024 Efficacy and safety of eliapixant in endometriosis-associated pelvic pain: the randomized, placebo-controlled phase 2b SCHUMANN study. BMC women's health 8 38890641
2008 Regulation of the E2F-associated phosphoprotein promoter by GC-box binding proteins. The international journal of biochemistry & cell biology 8 18588995
2021 Structure-function assessment of 3D-printed porous scaffolds by a low-cost/open source fused filament fabrication printer. Materials science & engineering. C, Materials for biological applications 6 33812577
2021 Endothelium-specific deletion of amyloid-β precursor protein exacerbates endothelial dysfunction induced by aging. Aging 6 34382945
2011 EAPP modulates the activity of p21 and Chk2. Cell cycle (Georgetown, Tex.) 6 21572256
2021 Structure and evolutionary trace-assisted screening of a residue swapping the substrate ambiguity and chiral specificity in an esterase. Computational and structural biotechnology journal 5 33995922
2015 Spatiotemporal Expression of EAPP Modulates Neuronal Apoptosis and Reactive Astrogliosis After Spinal Cord Injury. Journal of cellular biochemistry 5 25704466
2012 Using c-Fos/c-Jun as hetero-dimer interaction model to optimize donor to acceptor concentration ratio range for three-filter fluorescence resonance energy transfer (FRET) measurement. Journal of microscopy 5 22971218
2007 Integrated electrochemical gluconic acid biosensor based on self-assembled monolayer-modified gold electrodes. Application to the analysis of gluconic acid in musts and wines. Journal of agricultural and food chemistry 5 17323970
2021 The effect of Cu dopants on electron transfer to O2 and the connection with acetone photocatalytic oxidations over nano-TiO2. Physical chemistry chemical physics : PCCP 4 33875994
2005 Folding of the SARS coronavirus spike glycoprotein immunological fragment (SARS_S1b): thermodynamic and kinetic investigation correlating with three-dimensional structural modeling. Biochemistry 4 15683230
2022 Interplay between β-Diimino and β-Diketiminato Ligands in Nickel Complexes Active in the Proton Reduction Reaction. Inorganic chemistry 3 36196853
2007 Induced and repressed genes after irradiation sensitizing by pentoxyphylline. International journal of cancer 3 17192923
2024 Mechanical loading of ex vivo bovine trabecular bone in 3D printed bioreactor chambers. Journal of the mechanical behavior of biomedical materials 2 38422872
2016 Genetic expression analysis of E2F-associated phosphoprotein in stress responses in the mouse. Gene 2 26802973
2021 Electric field controlled uphill electron migration along α-helical oligopeptides. Physical chemistry chemical physics : PCCP 1 33399139

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