Affinage

PCGF1

Polycomb group RING finger protein 1 · UniProt Q9BSM1

Length
259 aa
Mass
30.3 kDa
Annotated
2026-04-29
28 papers in source corpus 18 papers cited in narrative 18 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PCGF1 is a core subunit of the non-canonical Polycomb repressive complex PRC1.1 that directs histone H2AK119 mono-ubiquitination and gene silencing at CpG island-containing promoters during development, differentiation, and immune regulation. Its RAWUL domain selectively binds BCOR/BCORL1 (but not PCGF2/4-associated partners), and this interaction creates an extended surface that recruits the KDM2B–SKP1 heterodimer, enabling CpG island targeting (PMID:23523425, PMID:27568929). PCGF1 stimulates RING1B-dependent H2AK119ub1 deposition and cooperates with PRC2-mediated H3K27me3 and DNMT-dependent DNA methylation to achieve stable transcriptional repression of developmental genes including HOX loci, MHC-I genes, and cell-cycle regulators such as p21 (PMID:18460542, PMID:34504070, PMID:38088808, PMID:36815373). Beyond canonical gene silencing, PCGF1-PRC1 functions at the replication fork to prevent inappropriate activator loading onto nascent DNA and ensure proper nucleosome deposition, thereby maintaining stem and progenitor cell differentiation potential (PMID:36443290).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 2005 Medium

    Establishing that PCGF1 is a nuclear protein whose transcriptional repression activity depends on its C-terminal domain and PKC-mediated phosphorylation at S183 provided the first functional map of the protein.

    Evidence Subcellular fractionation, reporter repression assay, and site-directed mutagenesis in cultured cells

    PMID:15620699

    Open questions at the time
    • No identification of endogenous target genes
    • PKC phosphorylation at S183 not validated in vivo with phospho-specific reagents
    • Repression mechanism (direct DNA binding vs. complex recruitment) unresolved
  2. 2006 Medium

    Demonstrating that PCGF1 binds the p21 promoter via a RARE element and competes with retinoic acid receptors established it as a sequence-directed transcriptional repressor at a defined genomic locus.

    Evidence ChIP, DNA pulldown, and luciferase reporter assay in cultured cells

    PMID:17088287

    Open questions at the time
    • Whether PCGF1 directly contacts DNA or acts through an intermediary was not resolved
    • Generality beyond p21 unknown
  3. 2008 High

    Showing that PCGF1 directly stimulates RING1B-mediated H2AK119 ubiquitination and that its recruitment depends on upstream EZH2/H3K27me3 established the catalytic function and hierarchical relationship between PRC1.1 and PRC2.

    Evidence In vitro ubiquitination assay, Co-IP, ChIP, and siRNA knockdown epistasis at HOX loci

    PMID:18460542

    Open questions at the time
    • Whether PCGF1 directly contacts H2A or acts solely through RING1B stimulation was unclear
    • No genome-wide target identification
  4. 2013 High

    Solving the PCGF1 RAWUL–BCOR PUFD crystal structure revealed the structural basis for selective assembly of PRC1.1 versus canonical PRC1, explaining why BCOR binds PCGF1/3 but not PCGF2/4.

    Evidence X-ray crystallography, analytical ultracentrifugation, and in vitro binding assays

    PMID:23523425

    Open questions at the time
    • Full quaternary architecture of PRC1.1 not yet resolved
    • No in vivo validation of selectivity-determining residues
  5. 2013 Medium

    Finding that PCGF1 directly activates Oct4 transcription by binding its promoter via a RARE element indicated that PCGF1 can act as both a repressor and an activator depending on genomic context.

    Evidence ChIP, luciferase reporter, dominant-negative, siRNA/overexpression in P19 cells

    PMID:24113379

    Open questions at the time
    • Mechanism distinguishing activation from repression at PCGF1-bound loci not determined
    • Single cell line (P19), generality unclear
  6. 2015 Medium

    Endogenous AP-MS identification of PCGF1 interacting with all known PRC1.1 subunits plus pluripotency factors (NANOG, OCT4, DPPA4) expanded the complex's interactome and linked it to the pluripotency network.

    Evidence Affinity purification–mass spectrometry under endogenous conditions with reciprocal Co-IP in ESCs

    PMID:26687479

    Open questions at the time
    • Whether pluripotency factor interactions are direct or bridged through PRC1.1 subunits unknown
    • Functional consequence of most interactions not tested
  7. 2016 High

    The crystal structure of a four-component KDM2B/SKP1/BCORL1/PCGF1 complex revealed how BCORL1 creates an extended interface enabling KDM2B recruitment, explaining PRC1.1 targeting to CpG islands.

    Evidence X-ray crystallography plus in vitro reconstitution and analytical ultracentrifugation

    PMID:27568929

    Open questions at the time
    • Structure lacks RING1B and the ubiquitin-transfer module
    • Chromatin-bound conformation unknown
  8. 2017 Medium

    CRISPR knockout of Pcgf1 in mouse ESCs revealed severe differentiation defects and reduced Ring1B/H2AK119ub at target genes, establishing a non-redundant role for PCGF1 in lineage specification.

    Evidence CRISPR/Cas9 knockout, RNA-seq, ChIP, in vitro differentiation in mouse ESCs

    PMID:28393894

    Open questions at the time
    • In vivo embryonic phenotype not examined
    • Extent of redundancy with other PCGF paralogs not systematically tested
  9. 2021 High

    Genome-wide analysis in differentiating ESCs showed that PCGF1-PRC1 deposits H2AK119ub1 de novo at differentiation-responsive loci and is required upstream for PRC2 recruitment, revising the earlier model of PRC2-first hierarchy.

    Evidence CRISPR/Cas9 knockout in mouse ESCs, ChIP-seq for H2AK119ub1 and H3K27me3, RNA-seq, embryoid body differentiation

    PMID:34504070

    Open questions at the time
    • Whether PCGF1-PRC1 initiates PRC2 recruitment at all loci or only differentiation-responsive ones is unresolved
    • Mechanism of de novo targeting upon differentiation unknown
  10. 2022 High

    iPOND proteomics and conditional knockout revealed that PCGF1-PRC1 acts at the replication fork to prevent activator and chromatin remodeler overloading on nascent DNA, establishing a replication-coupled function beyond steady-state gene silencing.

    Evidence Conditional KO in HSPCs, iPOND, ChIP-seq, ATAC-seq

    PMID:36443290

    Open questions at the time
    • Whether replication fork function is specific to PCGF1-PRC1 or shared by other variant PRC1 complexes not tested
    • Structural basis for fork association unknown
  11. 2024 Medium

    CRISPR screening identified PCGF1-PRC1 as a silencer of MHC-I genes via H2AK119ub deposition, opposed by BAP1 deubiquitination, linking PRC1.1 to immune evasion in cancer.

    Evidence Genome-wide CRISPR screen, ChIP, siRNA knockdown, T cell killing assay

    PMID:38088808

    Open questions at the time
    • Whether PCGF1 directly occupies MHC-I promoters or acts indirectly not fully resolved
    • In vivo tumor immune evasion role not tested

Open questions

Synthesis pass · forward-looking unresolved questions
  • How PCGF1-PRC1 selects target loci in a context-dependent manner (repression at some promoters, activation at others) and what determines its differential catalytic competence relative to other PRC1 subtypes on chromatin remain open questions.
  • No structure of full PCGF1-PRC1 on a nucleosome substrate
  • Mechanism of context-dependent activation versus repression unresolved
  • In vivo requirement during mammalian embryogenesis not reported

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140096 catalytic activity, acting on a protein 5 GO:0140110 transcription regulator activity 4 GO:0042393 histone binding 2
Localization
GO:0005694 chromosome 2 GO:0005634 nucleus 1
Pathway
R-HSA-4839726 Chromatin organization 5 R-HSA-74160 Gene expression (Transcription) 3 R-HSA-1266738 Developmental Biology 2 R-HSA-168256 Immune System 1 R-HSA-73894 DNA Repair 1
Partners
BCORBCORL1DNMT3AEZH2KDM2BMORC4RNF2SKP1
Complex memberships
FRRUC (FBXL10-RNF68-RNF2 ubiquitin ligase complex)PRC1.1 (variant Polycomb repressive complex 1.1)

Evidence

Reading pass · 18 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2013 Crystal structure of PCGF1 RAWUL domain in complex with BCOR PUFD domain reveals that BCOR PUFD selectively binds PCGF1 (and PCGF3) but not PCGF2 (MEL18) or PCGF4 (BMI1), with selectivity determined by specific residues within the RAWUL interaction surface. X-ray crystallography, in vitro binding assays, analytical ultracentrifugation Structure High 23523425
2016 Crystal structure of KDM2B/SKP1/BCORL1/PCGF1 complex reveals that the BCORL1 PUFD domain positions residues preceding the PCGF1 RAWUL domain to create an extended interface for interaction with KDM2B, enabling recruitment of PRC1.1 to CpG islands; a minimal four-component PRC1.1 complex can be reconstituted from KDM2B/SKP1 and BCORL1/PCGF1 subcomplexes. X-ray crystallography, in vitro assembly assays, analytical ultracentrifugation Structure High 27568929
2008 PCGF1 (NSPc1) stimulates histone H2A ubiquitination in vivo and in vitro through direct interaction with both RING2 and H2A, and cooperates with EZH2 and DNMT1 in HOX gene (HOXA7) silencing; EZH2-mediated H3K27me3 is required upstream for NSPc1 recruitment and H2A ubiquitination. In vitro ubiquitination assay, Co-IP, ChIP, siRNA knockdown, RT-PCR Nucleic Acids Research High 18460542
2005 NSPc1 (PCGF1) localizes predominantly to the nucleus and mediates transcriptional repression; the C-terminal domain and PKC phosphorylation site at S183 are required for its transcriptional repression activity. Western blotting, subcellular fractionation, reporter repression assay, site-directed mutagenesis FEBS Letters Medium 15620699
2006 NSPc1 (PCGF1) represses p21Waf1/Cip1 transcription by binding to the −1357 to −1083 region of its promoter via the RARE element, competing with RA receptors at this site in vivo and in vitro. Luciferase reporter assay, ChIP, DNA pulldown, RT-PCR Nucleic Acids Research Medium 17088287
2015 PCGF1 physically interacts with all known components of the variant PRC1 complex (including BCOR and KDM2B) and additionally interacts with pluripotency factors NANOG, OCT4, PATZ1, and DPPA4 under endogenous conditions; knockdown of PCGF1 reduces DPPA4 expression at mRNA and protein levels. Affinity purification–mass spectrometry (AP-MS) under endogenous conditions, reciprocal Co-IP, siRNA knockdown Scientific Reports Medium 26687479
2021 PCGF1-containing variant PRC1 (PCGF1-PRC1) mediates differentiation-associated transcriptional downregulation by depositing H2AK119ub1 and recruiting PRC2 to target gene loci upon differentiation cues; loss of PCGF1-PRC1 disrupts both H2AK119ub1 deposition and PRC2 recruitment, causing aberrant target gene expression. CRISPR/Cas9 knockout in mouse ESCs, ChIP-seq, RNA-seq, embryoid body differentiation Nature Communications High 34504070
2017 Loss of Pcgf1 in mouse ESCs (CRISPR/Cas9) causes severe differentiation defects and reduces Ring1B and H2AK119ub1 binding at target genes, revealing a role for Pcgf1 in gene activation during lineage specification in addition to repression. CRISPR/Cas9 knockout, RNA-seq, ChIP, in vitro differentiation assays Scientific Reports Medium 28393894
2022 PCGF1-PRC1 localizes at the replication fork and prevents overloading of activators and chromatin remodeling factors on nascent DNA, enabling proper nucleosome deposition and downstream PRC2-mediated repression of target genes (e.g., Hmga2), thereby maintaining hematopoietic stem and progenitor cell differentiation potential. Conditional KO in HSPCs, iPOND (nascent DNA proteomics), ChIP-seq, RNA-seq, ATAC-seq Nature Communications High 36443290
2018 The FBXL10 (KDM2B)–RNF68–RNF2 ubiquitin ligase complex (FRRUC), which contains PCGF1 as a core component (FBXL10 = KDM2B), is recruited to sites of DNA damage in a PARP1- and TIMELESS-dependent manner to mono-ubiquitylate H2A at K119, promoting H2A.Z incorporation and homologous recombination repair. Live-cell imaging, Co-IP, ChIP, siRNA/shRNA knockdown, in vitro ubiquitylation, HR reporter assay eLife Medium 29985131
2024 PCGF1-containing PRC1 facilitates deposition of H2AK119ub at MHC-I gene promoters to silence MHC-I transcription; BAP1 opposes this by removing the ubiquitin mark; PCGF1 depletion restores MHC-I expression and T cell-mediated tumor killing. Genome-wide CRISPR screen, ChIP, siRNA knockdown, T cell killing assay Journal of Immunology Medium 38088808
2013 NSPc1 (PCGF1) directly activates Oct4 transcription by binding to the −1021 to −784 region of the Oct4 promoter in a RARE-dependent manner, maintaining the pluripotency network (Oct4-Nanog-Sox2) in P19 embryonal carcinoma cells. Luciferase reporter assay, ChIP, dominant-negative analysis, siRNA/overexpression Biochemical and Biophysical Research Communications Medium 24113379
2024 PCGF1 inhibits MMP10 transcription by upregulating RING1B-mediated H2AK119ub and EZH2-mediated H3K27me3 at the MMP10 promoter in microglia, thereby suppressing NF-κB/MAPK-driven neuroinflammation. ChIP, siRNA knockdown in vivo and in vitro, cytokine measurement, behavioral assays Molecular Psychiatry Medium 39215186
2023 PCGF1 represses HOXA11 expression in trophoblast cells by recruiting DNMT3a to maintain DNA methylation at the HOXA11 promoter; the interplay between NSPc1 and DNMT3a cooperatively silences HOXA11 and promotes apoptosis. ChIP, bisulfite sequencing, siRNA knockdown, Co-IP, apoptosis assays Acta Biochimica et Biophysica Sinica Medium 36815373
2017 NSPc1 (PCGF1) epigenetically represses RDH16 expression by directly binding to the −1073 to −823 region of the RDH16 promoter, suppressing ATRA synthesis and promoting cancer stem cell self-renewal in glioma. ChIP, siRNA knockdown, sphere formation assay, xenograft assay Oncogene Medium 28394339
2023 MORC4 physically interacts with PCGF1 (Co-IP) and augments PCGF1-mediated transcriptional repression of CDKN1A, promoting colorectal cancer progression; MORC4 itself is degraded via HECW2-mediated ubiquitination. Co-immunoprecipitation, luciferase reporter assay, siRNA knockdown, ChIP Cancer Gene Therapy Low 36932196
2019 NSPc1 (PCGF1) protein complex binds lncRNAs MALAT1, SOX2OT, and ANRIL in glioma cells as demonstrated by RNA immunoprecipitation, and co-regulation of NSPc1 with these lncRNAs affects p21 and OCT4 transcription. RNA immunoprecipitation (RIP), RT-PCR, siRNA knockdown Oncology Letters Low 31186810
2024 Single-molecule imaging reveals that PCGF1-containing variant PRC1 transiently samples chromatin until reaching a catalytically competent nucleosome-bound state that enables E2 recruitment and ubiquitin transfer; PCGF1-PRC1 has a distinct (lower) probability of achieving this catalytically competent state compared to PCGF4-PRC1, explaining subtype-specific activity differences. Single-molecule fluorescence microscopy, in vitro reconstituted ubiquitylation assay on nucleosomal arrays bioRxivpreprint Medium bio_10.1101_2024.10.25.620026

Source papers

Stage 0 corpus · 28 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2013 Structure of the polycomb group protein PCGF1 in complex with BCOR reveals basis for binding selectivity of PCGF homologs. Structure (London, England : 1993) 86 23523425
2008 Cooperation between EZH2, NSPc1-mediated histone H2A ubiquitination and Dnmt1 in HOX gene silencing. Nucleic acids research 82 18460542
2016 KDM2B Recruitment of the Polycomb Group Complex, PRC1.1, Requires Cooperation between PCGF1 and BCORL1. Structure (London, England : 1993) 49 27568929
2018 PARP1-dependent recruitment of the FBXL10-RNF68-RNF2 ubiquitin ligase to sites of DNA damage controls H2A.Z loading. eLife 46 29985131
2015 The variant Polycomb Repressor Complex 1 component PCGF1 interacts with a pluripotency sub-network that includes DPPA4, a regulator of embryogenesis. Scientific reports 43 26687479
2017 NSPc1 promotes cancer stem cell self-renewal by repressing the synthesis of all-trans retinoic acid via targeting RDH16 in malignant glioma. Oncogene 39 28394339
2006 NSPc1 is a cell growth regulator that acts as a transcriptional repressor of p21Waf1/Cip1 via the RARE element. Nucleic acids research 33 17088287
2021 PCGF1 promotes epigenetic activation of stemness markers and colorectal cancer stem cell enrichment. Cell death & disease 30 34148069
2021 Variant PCGF1-PRC1 links PRC2 recruitment with differentiation-associated transcriptional inactivation at target genes. Nature communications 29 34504070
2017 Loss of Polycomb Group Protein Pcgf1 Severely Compromises Proper Differentiation of Embryonic Stem Cells. Scientific reports 28 28393894
2005 NSPc1, a mainly nuclear localized protein of novel PcG family members, has a transcription repression activity related to its PKC phosphorylation site at S183. FEBS letters 24 15620699
2001 NSPc1, a novel mammalian Polycomb gene, is expressed in neural crest-derived structures of the peripheral nervous system. Mechanisms of development 24 11287196
2016 The Polycomb Group Protein Pcgf1 Is Dispensable in Zebrafish but Involved in Early Growth and Aging. PloS one 21 27442247
2024 Microglial PCGF1 alleviates neuroinflammation associated depressive behavior in adolescent mice. Molecular psychiatry 16 39215186
2013 Nspc1 regulates the key pluripotent Oct4-Nanog-Sox2 axis in P19 embryonal carcinoma cells via directly activating Oct4. Biochemical and biophysical research communications 15 24113379
2022 PCGF1-PRC1 links chromatin repression with DNA replication during hematopoietic cell lineage commitment. Nature communications 13 36443290
2017 MicroRNA‑320a inhibition decreases insulin‑induced KGN cell proliferation and apoptosis by targeting PCGF1. Molecular medicine reports 11 28849208
2021 Pcgf1 Regulates Early Neural Tube Development Through Histone Methylation in Zebrafish. Frontiers in cell and developmental biology 9 33575252
2020 Repression of PCGF1 Decreases the Proliferation of Glioblastoma Cells in Association with Inactivation of c-Myc Signaling Pathway. OncoTargets and therapy 9 32021272
2019 lncRNAs combine and crosstalk with NSPc1 in ATRA-induced differentiation of U87 glioma cells. Oncology letters 8 31186810
2024 Ubiquitin-specific peptidase 15 regulates the TFAP4/PCGF1 axis facilitating liver metastasis of colorectal cancer and cell stemness. Biochemical pharmacology 7 38801926
2023 MORC4 plays a tumor-promoting role in colorectal cancer via regulating PCGF1/CDKN1A axis in vitro and in vivo. Cancer gene therapy 7 36932196
2023 Cooperation between NSPc1 and DNA methylation represses HOXA11 expression and promotes apoptosis of trophoblast cells during preeclampsia. Acta biochimica et biophysica Sinica 6 36815373
2019 NSPc1 polycomb protein complex binds and cross‑talks to lncRNAs in glioma H4 cells. Oncology reports 6 30720120
2024 Balanced Epigenetic Regulation of MHC Class I Expression in Tumor Cells by the Histone Ubiquitin Modifiers BAP1 and PCGF1. Journal of immunology (Baltimore, Md. : 1950) 4 38088808
2023 Pcgf1 gene disruption reveals primary involvement of epigenetic mechanism in neuronal subtype specification in the enteric nervous system. Development, growth & differentiation 4 37452641
2008 [Expression pattern of polycomb gene Nspc1 at the early developmental stage in zebrafish]. Zhongguo yi xue ke xue yuan xue bao. Acta Academiae Medicinae Sinicae 3 19024384
2022 [PCGF1 is highly expressed in rectal adenocarcinoma and silencing PCGF1 inhibits proliferation of rectal adenocarcinoma cells in vitro]. Nan fang yi ke da xue xue bao = Journal of Southern Medical University 1 36210701