Affinage

BRD8

Bromodomain-containing protein 8 · UniProt Q9H0E9

Length
1235 aa
Mass
135.3 kDa
Annotated
2026-06-09
15 papers in source corpus 11 papers cited in narrative 11 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

BRD8 is a bromodomain-containing acetyl-lysine reader subunit of the NuA4/EP400-TIP60 (KAT5) histone acetyltransferase complex that uses its bromodomain to engage acetylated histone H4 and direct the incorporation of histone variant H2A.Z into chromatin, thereby governing histone acetylation, chromatin accessibility, and target-gene expression (PMID:36544023, PMID:23064015, PMID:37123243, PMID:39656858). By localizing and stabilizing KAT5 at chromatin genome-wide, BRD8 controls the acetylation state of specific gene programs: it maintains H2A.Z-dependent repressive chromatin at p53 target loci to suppress p53 transactivation and sustain proliferation, such that bromodomain targeting or depletion displaces H2A.Z, opens chromatin, activates p53 and p21, and enforces G1/S arrest and apoptosis (PMID:36544023, PMID:30237520). BRD8 depletion concomitantly reduces KAT5 protein levels and KAT5-dependent gene expression, lowers H4K16 acetylation, and triggers replication stress and ATM-CHK2 DNA damage signaling, indicating a requirement for BRD8 in p400/TIP60 recruitment supporting genome stability (PMID:30237520, PMID:32860757). BRD8 also drives developmental and lineage programs—promoting PPARγ-dependent adipogenesis through H2A.Z deposition (PMID:23064015) and maintaining open chromatin at somatic genes to impede the conversion of primed epiblast stem cells to the naive state (PMID:39656858)—and acts in transcription at additional loci, co-occupying genomic sites with CTCF and regulating innate immune response and cell cycle genes (PMID:33476703). Beyond its canonical complex role, BRD8 transactivates pre-replicative complex genes together with AP-1 independently of TIP60, and its own protein stability is bromodomain-dependent and protected from ubiquitin-mediated degradation via interaction with an MRG domain binding protein (PMID:37123243). In cancer, BRD8 mediates ER/HER2 signaling crosstalk by directing EP400-dependent H2A.Z acetylation at ER, FOX, and ETS motif regions and is required for neratinib-induced ER activation in HR+/HER2+ breast cancer (PMID:41886605).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2009 Medium

    Established BRD8 as a functional accessory subunit of the human NuA4-HAT (TRRAP/TIP60) complex with a role in drug resistance, linking it for the first time to a defined chromatin-modifying machinery and a cancer phenotype.

    Evidence siRNA knockdown and stable overexpression in HeLa/colorectal cancer lines with viability and spindle-poison sensitivity readouts

    PMID:19787264

    Open questions at the time
    • Did not define the molecular activity of BRD8 within the complex
    • No direct demonstration of bromodomain function or histone reading
    • Mechanism of taxol/MG132 sensitization unresolved
  2. 2012 High

    Showed BRD8 within the p400 complex directs histone variant H2A.Z incorporation to activate a defined gene program, establishing its role in chromatin-templated transcriptional activation during differentiation.

    Evidence shRNA knockdown and ChIP with adipogenesis/lipid accumulation assays in 3T3-L1 preadipocytes

    PMID:23064015

    Open questions at the time
    • Did not test whether the bromodomain mediates chromatin targeting
    • Mechanism connecting H2A.Z deposition to PPARγ accumulation not resolved
    • Restricted to adipogenic context
  3. 2018 Medium

    Placed BRD8 upstream of both the p53 pathway and the DNA damage response, revealing that loss of BRD8 derepresses p53 and induces replication stress with ATM-CHK2 activation, implicating it in p400/TIP60-dependent genome maintenance.

    Evidence siRNA knockdown with flow cytometry, Western blots for p21/CHK1-2/RPA32-P/H4K16ac in cell lines

    PMID:30237520

    Open questions at the time
    • Epistatic placement does not establish direct chromatin recruitment mechanism
    • Whether DDR activation is p53-dependent or parallel unresolved
    • No genome-wide occupancy data
  4. 2020 Medium

    Demonstrated BRD8 acts upstream of KAT5 protein stability and KAT5-target gene expression and is itself controlled by miR-876-3p, defining a regulatory hierarchy and an upstream regulator in hepatocellular carcinoma.

    Evidence siRNA/overexpression, luciferase reporter validation of miRNA targeting, Western blot and viability/apoptosis assays in HCC cells

    PMID:32860757

    Open questions at the time
    • Mechanism by which BRD8 stabilizes KAT5 protein not defined
    • No direct chromatin co-occupancy data
    • Single cancer type
  5. 2021 Medium

    Mapped genome-wide BRD8 occupancy showing co-localization with CTCF and a functional role in innate immune and cell cycle gene regulation, broadening its transcriptional targets beyond differentiation.

    Evidence ChIP-seq, siRNA depletion, motif analysis, and cytokine/peptide secretion assays in human lung epithelial cells

    PMID:33476703

    Open questions at the time
    • Functional significance of CTCF co-occupancy not mechanistically dissected
    • Direct vs indirect regulation of immune genes unclear
  6. 2021 Medium

    Confirmed BRD8 as a bromodomain subunit of NuA4 by chemoproteomics and delivered first-in-class selective small-molecule probes, enabling pharmacological interrogation of its bromodomain.

    Evidence Chemoproteomic affinity-matrix pulldown/MS and homology-model-guided probe design with cellular activity assays

    PMID:34515462

    Open questions at the time
    • Endogenous acetyl-lysine ligand specificity not defined here
    • No structural model of bromodomain-histone engagement
  7. 2022 High

    Defined the disease-relevant mechanism: BRD8 maintains H2A.Z at p53 target loci to enforce repressive chromatin in TP53-wild-type GBM, and bromodomain targeting reactivates p53 and arrests proliferation, validating the bromodomain as a therapeutic target.

    Evidence ChIP, chromatin accessibility, bromodomain targeting with functional readout, loss-of-function in patient-derived GBM models

    PMID:36544023

    Open questions at the time
    • Whether p53 repression generalizes beyond GBM not established here
    • Direct acetyl-mark read by the bromodomain at these loci not resolved
  8. 2023 High

    Revealed TIP60-independent functions of BRD8: bromodomain-dependent H4 binding required for its own protein stability and transactivation, AP-1-coordinated regulation of pre-replicative complex genes, and stabilization via an MRG domain binding protein against ubiquitin-dependent degradation.

    Evidence Transcriptomics, genome-wide BRD8 ChIP-seq, Co-IP, bromodomain mutagenesis, and cell-cycle analysis in colorectal cancer cells

    PMID:37123243

    Open questions at the time
    • Identity/mechanism of the deubiquitinating or stabilizing pathway incompletely defined
    • How AP-1 cooperation is achieved at the molecular level unresolved
  9. 2024 High

    Established BRD8 as a histone-acetylation reader that localizes KAT5 genome-wide, demonstrating in epiblast stem cells that it sustains open chromatin and acetylation to gate cell-fate transitions.

    Evidence ATAC-seq, histone-acetylation ChIP-seq, Brd8 depletion, and EpiSC-to-naive ESC conversion assays

    PMID:39656858

    Open questions at the time
    • Precise acetyl-lysine marks read at each locus class not fully enumerated
    • Generalizability of the KAT5-localizer role across cell types
  10. 2026 High

    Extended BRD8's reader function to oncogenic signaling crosstalk, showing it directs EP400-dependent H2A.Z acetylation at ER/FOX/ETS regions to couple ER and HER2 signaling and confer drug resistance in HR+/HER2+ breast cancer.

    Evidence scRNA-seq, snATAC-seq, BRD8 depletion, ER-HER2 Co-IP, H2AZac ChIP, drug-sensitivity assays with clinical-trial validation

    PMID:41886605

    Open questions at the time
    • Direct molecular basis of the ER-HER2 interaction disruption upon BRD8 loss not fully resolved
    • Whether the bromodomain is required for this specific function not isolated

Open questions

Synthesis pass · forward-looking unresolved questions
  • How BRD8's bromodomain specificity (which acetyl-lysine marks on H4/H2A.Z it reads) and its switch between TIP60/KAT5-dependent and TIP60-independent functions are mechanistically partitioned across contexts remains unresolved.
  • No structural model of bromodomain-acetyl-histone complex in the timeline
  • Determinants selecting between KAT5-dependent and AP-1-dependent transcriptional programs unknown
  • Mechanism coupling chromatin reading to KAT5 protein stabilization undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0042393 histone binding 3 GO:0060090 molecular adaptor activity 3 GO:0140110 transcription regulator activity 2
Localization
GO:0005634 nucleus 4 GO:0000228 nuclear chromosome 3
Pathway
R-HSA-4839726 Chromatin organization 3 R-HSA-74160 Gene expression (Transcription) 3 R-HSA-1640170 Cell Cycle 2 R-HSA-1643685 Disease 2 R-HSA-73894 DNA Repair 1
Complex memberships
EP400/p400 complexNuA4/TIP60 histone acetyltransferase complex

Evidence

Reading pass · 11 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2022 BRD8 maintains H2AZ occupancy at p53 target loci through the EP400 histone acetyltransferase complex, creating a repressive chromatin state that prevents p53 transactivation and sustains proliferation in TP53-wild-type GBM. Targeting the bromodomain of BRD8 displaces H2AZ, enhances chromatin accessibility, and engages p53 transactivation, enforcing cell cycle arrest. ChIP, chromatin accessibility assays, bromodomain inhibition/targeting, loss-of-function in patient-derived GBM models, gene expression analysis Nature High 36544023
2012 BRD8, as a subunit of the p400 complex, promotes adipogenesis by targeting and incorporating histone variant H2A.Z into transcriptional regulatory regions of PPARγ target genes; shRNA knockdown of Brd8 blocks H2A.Z incorporation, PPARγ accumulation, p400 and RNA Pol II recruitment, and abrogates fat cell differentiation. shRNA knockdown, chromatin immunoprecipitation (ChIP), lipid accumulation assays in 3T3-L1 preadipocytes Endocrinology High 23064015
2009 BRD8 is an accessory subunit of the human NuA4-HAT (TRRAP/TIP60) complex and confers resistance to spindle poisons; siRNA knockdown of BRD8 induces cell death/growth delay in colorectal cancer lines and sensitizes surviving cells to spindle poisons and proteasome inhibitor MG132, while overexpression of at least one BRD8 isoform confers growth advantage and taxol resistance. siRNA knockdown, stable overexpression in HeLa cells, cell viability assays, expression cloning International journal of oncology Medium 19787264
2018 Knockdown of BRD8 activates the p53 transcriptional pathway, upregulating p21 and pro-apoptotic genes, inducing G1/S arrest and apoptosis. BRD8 depletion also triggers the DNA damage response (DDR) under normal growth conditions, activating ATM-CHK2 signaling, reducing CHK1, inducing replication stress (enhanced RPA32 phosphorylation), and reducing H4K16 acetylation, suggesting BRD8 is required for p400/Tip60 complex recruitment/stabilization at chromatin for DNA repair. siRNA knockdown, flow cytometry (cell cycle/apoptosis), Western blot (p21, CHK1/2, RPA32 phosphorylation, H4K16ac), DNA damage foci detection Scientific reports Medium 30237520
2023 BRD8 protein accumulates in colorectal cancer cells through inhibition of ubiquitin-dependent degradation via interaction with MRG domain binding protein. BRD8 transactivates genes independently of TIP60, regulates multiple subunits of the pre-replicative complex in concert with activator protein-1 (AP-1), and its bromodomain is indispensable for interaction with histone H4, transcriptional regulation, and its own protein stability. BRD8 depletion causes G1 cell cycle arrest. Transcriptome analysis, genome-wide BRD8 ChIP-seq, co-immunoprecipitation, bromodomain mutagenesis, siRNA knockdown, cell cycle analysis iScience High 37123243
2021 A chemoproteomics approach using a functionalized BRD9 ligand affinity matrix identified BRD8 as a bromodomain-containing subunit of the NuA4 complex; selective and cellularly active first-in-class small molecule probes for BRD8 were developed using homology-model-guided design. Chemoproteomics (affinity matrix pulldown/MS), homology model-guided probe design, cellular activity assays ACS chemical biology Medium 34515462
2020 BRD8 knockdown reduces KAT5 (TIP60) protein levels and expression of KAT5-induced genes in HCC cells, placing BRD8 upstream of KAT5 in regulating HCC cell proliferation and apoptosis resistance. miR-876-3p directly targets BRD8 mRNA (confirmed by luciferase reporter assay), negatively regulating BRD8 expression. siRNA knockdown, overexpression, luciferase reporter assay, Western blot, RT-qPCR, cell viability and apoptosis assays Archives of biochemistry and biophysics Medium 32860757
2021 BRD8 occupies genome-wide sites in human lung epithelial cells, co-occupying regions with CTCF. BRD8 depletion increases secretion of beta-defensin 1 and multiple chemokines and reduces cell proliferation, implicating BRD8 in regulation of innate immune response genes and the cell cycle. ChIP-seq (genome-wide BRD8 occupancy), siRNA depletion, gene expression analysis, motif over-representation analysis, cytokine/peptide secretion assays Molecular and cellular endocrinology Medium 33476703
2024 BRD8 reads histone acetylation to localize the histone acetyltransferase KAT5 genome-wide; BRD8 maintains open chromatin at somatic genes and histone acetylation at naive-specific genes in primed mouse epiblast stem cells, thereby impeding conversion to naive ESCs. Reduction of Brd8 reduces histone acetylation at naive-specific genes and permits faster acquisition of accessible chromatin at those loci during cell type conversion. ATAC-seq, ChIP-seq (histone acetylation), Brd8 knockdown/depletion, cell type conversion assays (EpiSC to naive ESC), chromatin accessibility analysis Advanced science High 39656858
2026 BRD8, as an acetyl-lysine reader in the EP400 complex, mediates ER/HER2 signaling crosstalk in HR+/HER2+ breast cancer. BRD8 expression increases after anti-HER2 treatment; its depletion disrupts ER-HER2 interaction and enhances drug sensitivity. BRD8 regulates chromatin opening (H2AZac deposition via EP400) at ER, FOX, and ETS transcription factor motif-containing regions after anti-HER2 treatment, and is required for neratinib-induced ER activation. Single-cell transcriptomics, single-nucleus ATAC-seq, BRD8 depletion, co-immunoprecipitation (ER-HER2), H2AZac ChIP, drug sensitivity assays, clinical trial validation Cancer research High 41886605
2025 BRD8 knockdown suppresses TGF-β1 upregulation, which in turn reduces M2-like tumor-associated macrophage (TAM2) polarization and decreases migration and invasion of colorectal cancer cells, placing BRD8 upstream of TGF-β1 in regulating the tumor immune microenvironment. siRNA knockdown, RT-qPCR, Western blot, flow cytometry (macrophage polarization), transwell migration/invasion assays, IHC/immunofluorescence Discover oncology Low 40720004

Source papers

Stage 0 corpus · 15 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2022 BRD8 maintains glioblastoma by epigenetic reprogramming of the p53 network. Nature 64 36544023
2017 Fusion of the genes BRD8 and PHF1 in endometrial stromal sarcoma. Genes, chromosomes & cancer 44 28758277
2009 BRD8 is a potential chemosensitizing target for spindle poisons in colorectal cancer therapy. International journal of oncology 30 19787264
2012 The p400/Brd8 chromatin remodeling complex promotes adipogenesis by incorporating histone variant H2A.Z at PPARγ target genes. Endocrinology 24 23064015
2018 Cellular Depletion of BRD8 Causes p53-Dependent Apoptosis and Induces a DNA Damage Response in Non-Stressed Cells. Scientific reports 17 30237520
2020 BRD8, which is negatively regulated by miR-876-3p, promotes the proliferation and apoptosis resistance of hepatocellular carcinoma cells via KAT5. Archives of biochemistry and biophysics 16 32860757
2021 The Bromodomain Containing 8 (BRD8) transcriptional network in human lung epithelial cells. Molecular and cellular endocrinology 11 33476703
2023 Bromodomain protein BRD8 regulates cell cycle progression in colorectal cancer cells through a TIP60-independent regulation of the pre-RC complex. iScience 10 37123243
2021 Chemoproteomics Enabled Discovery of Selective Probes for NuA4 Factor BRD8. ACS chemical biology 8 34515462
2024 Understanding the role of BRD8 in human carcinogenesis. Cancer science 5 38965933
2021 Ossifying low grade endometrial stromal sarcoma with PHF1-BRD8 fusion. Cancer genetics 4 33975123
2024 BRD8 Guards the Pluripotent State by Sensing and Maintaining Histone Acetylation. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 3 39656858
2024 Targeting bromodomian-containing protein 8 (BRD8): An advanced tool to interrogate BRD8. European journal of medicinal chemistry 2 38401187
2025 BRD8 inhibits colorectal cancer progression through TGF-β1-mediated tumor-associated macrophage recruitment. Discover oncology 1 40720004
2026 Integrated Multi-omic Profiling Identifies BRD8/EP400 as a Pivotal Chromatin Module Mediating Anti-HER2 Response in HR+/HER2+ Breast Cancer. Cancer research 0 41886605

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