Affinage

PLRG1

Pleiotropic regulator 1 · UniProt O43660

Length
514 aa
Mass
57.2 kDa
Annotated
2026-06-10
28 papers in source corpus 14 papers cited in narrative 14 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

PLRG1 is a conserved WD40-domain protein that functions as an essential structural and regulatory subunit of the Prp19/Pso4 (NineTeen) complex, coupling pre-mRNA splicing to genome maintenance (PMID:11544257, PMID:29547724). Within this complex, PLRG1 directly binds the C-terminus of CDC5L via its WD40 domain, and this interaction is required for pre-mRNA splicing progression: peptides disrupting the CDC5L–PLRG1 interface inhibit in vitro splicing, an effect rescued by the partner protein (PMID:11544257, PMID:14576297). Stepwise assembly of SPF27, CDC5L, and PLRG1 onto the autoinhibited Prp19 tetramer relieves autoinhibition and activates Prp19 E3 ubiquitin ligase activity, with PLRG1's WD40 surface communicating with Prp19 to enable ligation (PMID:29547724); two WD40 loops become ordered upon engagement of other splicing factors during spliceosome assembly (PMID:33239170). PLRG1 is integrated into SC35-positive nuclear speckles in a phase-separation-dependent manner under control of USP42-mediated deubiquitylation, linking its localization to splicing fidelity (PMID:33731873). Beyond splicing, the PLRG1-containing Pso4 complex acts in DNA interstrand cross-link repair and in ATR-mediated S-phase checkpoint signaling, where it colocalizes with RPA at damage sites and is required for ATRIP recruitment, CHK1 activation, and RPA2 phosphorylation (PMID:16223718, PMID:24443570). Genetic loss of PLRG1 blocks S-phase progression, drives p53-dependent apoptosis with elevated γ-H2AX, and abolishes nuclear retention of CDC5L (PMID:19307306). PLRG1 also has a non-canonical transcriptional role, co-occupying the CCND1 promoter and superenhancer with DHX37 to activate cyclin D1 and promote proliferation (PMID:35290436).

Mechanistic history

Synthesis pass · year-by-year structured walk · 14 steps
  1. 2001 High

    Established the direct molecular contact underlying PLRG1's splicing function by mapping a WD40-domain interaction with the CDC5L C-terminus and showing it is essential for splicing.

    Evidence In vitro binding, co-IP, domain mapping, and splicing inhibition in HeLa nuclear extract

    PMID:11544257

    Open questions at the time
    • Does not define how this interaction nucleates the larger complex
    • No structural model of the bound interface at this stage
  2. 2003 High

    Confirmed the functional necessity of the CDC5L–PLRG1 interface for splicing using competitive peptides and a recombinant-protein rescue control.

    Evidence In vitro splicing assay with competing peptides and rescue

    PMID:14576297

    Open questions at the time
    • Step in the splicing cycle blocked not defined
    • PLRG1 catalytic or scaffolding mechanism still unknown
  3. 2005 Medium

    Extended PLRG1 beyond splicing by placing the Pso4 complex in an early stage of DNA interstrand cross-link repair.

    Evidence Cell-free ICL processing assay with immunodepletion and co-IP

    PMID:16223718

    Open questions at the time
    • PLRG1's individual contribution inferred from complex depletion, not isolated knockdown
    • Direct enzymatic role of PLRG1 in ICL processing unresolved
  4. 2007 Medium

    Showed DNA damage remodels the complex, as ubiquitylated oligomeric Prp19 loses interaction with both CDC5L and PLRG1.

    Evidence Non-reducing SDS-PAGE, co-IP, and chromatin fractionation after damage

    PMID:17276391

    Open questions at the time
    • Single lab, single method set
    • Functional consequence of complex disassembly not directly tested
  5. 2009 High

    Defined PLRG1 as essential in vivo for S-phase progression, suppression of p53-dependent apoptosis, and nuclear retention of CDC5L.

    Evidence Conditional knockout mice, PLRG1-deficient MEFs, cell-cycle/apoptosis assays, p53 knockdown rescue in MEFs and zebrafish

    PMID:19307306

    Open questions at the time
    • Whether the phenotype reflects splicing loss or a distinct activity not separated
    • Mechanism linking PLRG1 loss to p53 activation unresolved
  6. 2009 Low

    Connected the PLRG1-containing complex to ATR-mediated checkpoint signaling through a CDC5L–ATR interaction.

    Evidence Co-IP, Cdc5L siRNA depletion, checkpoint kinase activation assays

    PMID:19633697

    Open questions at the time
    • PLRG1's role inferred from complex membership, not a direct PLRG1 experiment
    • PLRG1 not shown to contact ATR
  7. 2010 Medium

    Placed PLRG1 in alternative splicing regulation via hnRNP-M, which bridges CDC5L and PLRG1 to influence splice-site choice.

    Evidence In vivo co-IP, deletion mapping, adeno-E1A minigene alternative splicing assay

    PMID:20467437

    Open questions at the time
    • Single lab
    • Direct PLRG1 contribution versus CDC5L not dissected
  8. 2014 Medium

    Resolved the checkpoint role by showing the PLRG1-containing Pso4 complex recruits ATRIP to damage sites and drives CHK1/RPA2 activation, with PLRG1 colocalizing with RPA.

    Evidence siRNA depletion, immunofluorescence colocalization, complex–RPA co-IP, in vitro ATR activation

    PMID:24443570

    Open questions at the time
    • PLRG1's individual requirement partly inferred from complex-level depletion
    • Direct PLRG1–RPA contact not mapped
  9. 2018 High

    Established the activation mechanism: PLRG1 is required to relieve Prp19 autoinhibition and switch on its E3 ubiquitin ligase activity through stepwise complex assembly.

    Evidence Crystallography of Prp19, mutagenesis, stepwise NTC reconstitution, in vitro ubiquitin ligation, crosslinking-MS

    PMID:29547724

    Open questions at the time
    • Physiological substrates of the activated ligase not enumerated here
    • How PLRG1 transmits the activating signal structurally only partially defined
  10. 2020 Medium

    Provided structural detail of the PLRG1 WD40 domain and showed conformational ordering of loops upon binding partners during spliceosome assembly.

    Evidence X-ray crystallography of apo WD40 domain, comparison with cryo-EM spliceosome structures

    PMID:33239170

    Open questions at the time
    • Limited functional validation beyond structural observation
    • Full-length PLRG1 context not crystallized
  11. 2021 Medium

    Identified an upstream regulatory layer: USP42-mediated deubiquitylation controls phase-separation-dependent integration of PLRG1 into nuclear speckles and thereby splicing function.

    Evidence Immunofluorescence colocalization, USP42 knockdown, splicing assays, phase separation assays, fractionation

    PMID:33731873

    Open questions at the time
    • Direct ubiquitylation sites on PLRG1 not mapped
    • Single lab
  12. 2022 Medium

    Revealed a non-canonical transcriptional function for PLRG1, co-occupying the CCND1 promoter and superenhancer with DHX37 to activate cyclin D1.

    Evidence Co-IP, ChIP-seq, ChIP at CCND1, proliferation assays in liver cancer cells

    PMID:35290436

    Open questions at the time
    • How a splicing factor is recruited to chromatin not defined
    • Single lab
  13. 2023 Medium

    Distinguished tumor-specific from normal-cell responses to PLRG1 loss, with cancer cells undergoing mitotic catastrophe and apoptosis versus protective G1 arrest in normal cells.

    Evidence siRNA knockdown, cell-cycle FACS, microtubule/DNA-damage immunofluorescence, apoptosis assays

    PMID:37817442

    Open questions at the time
    • Molecular basis of the tumor-versus-normal difference unresolved
    • Single lab
  14. 2024 Medium

    Placed PLRG1 downstream of YBX1 transcriptional control in promoting EMT in hepatocellular carcinoma.

    Evidence ChIP and luciferase at PLRG1 promoter, YBX1 overexpression, PLRG1 knockdown rescue, EMT marker and migration/invasion assays

    PMID:39400789

    Open questions at the time
    • Mechanism by which PLRG1 drives EMT downstream not defined
    • Single lab

Open questions

Synthesis pass · forward-looking unresolved questions
  • How PLRG1 partitions between its canonical splicing/E3-activation role and its chromatin-associated transcriptional function, and what governs that switch, remains unresolved.
  • No unified model linking splicing and transcriptional roles
  • Substrate spectrum of the PLRG1-activated Prp19 ligase incomplete
  • Chromatin recruitment mechanism unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140098 catalytic activity, acting on RNA 2 GO:0008092 cytoskeletal protein binding 1 GO:0098772 molecular function regulator activity 1 GO:0140096 catalytic activity, acting on a protein 1
Localization
GO:0005634 nucleus 2 GO:0000228 nuclear chromosome 1 GO:0005654 nucleoplasm 1
Pathway
R-HSA-8953854 Metabolism of RNA 3 R-HSA-1640170 Cell Cycle 2 R-HSA-73894 DNA Repair 2 R-HSA-74160 Gene expression (Transcription) 1
Complex memberships
Prp19/Pso4 complex (NineTeen Complex, NTC)spliceosome

Evidence

Reading pass · 14 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2001 The WD40 domain of PLRG1 directly interacts with the carboxyl-terminal region of CDC5L in vitro and in vivo. A bacterially expressed CDC5L fragment containing the PLRG1-interaction domain disrupts the CDC5L-PLRG1 interaction in HeLa nuclear extract and inhibits pre-mRNA splicing, demonstrating that this direct interaction is essential for pre-mRNA splicing progression. In vitro binding assay, co-immunoprecipitation, domain mapping by mutagenesis, in vitro splicing inhibition assay The Journal of biological chemistry High 11544257
2003 Peptides derived from the WD40-containing interaction domain of PLRG1 and the C-terminal domain of CDC5L inhibit pre-mRNA splicing in vitro; this inhibition is rescued by pre-incubating the peptides with the corresponding partner protein, confirming that the CDC5L–PLRG1 interaction is essential for the splicing mechanism. In vitro splicing assay with competing peptides, rescue by recombinant protein pre-incubation Nucleic acids research High 14576297
2005 PLRG1 is a core component of the Pso4/Prp19–Cdc5L–Plrg1–Spf27 complex (Pso4 complex) that is required for processing of psoralen DNA interstrand cross-links (ICLs) in a cell-free biochemical assay; the complex participates in an early stage of ICL repair alongside MutSβ, Ercc1-Xpf, RPA, and PCNA. Cell-free ICL processing assay, immunodepletion, co-immunoprecipitation showing Pso4 complex–WRN association The Journal of biological chemistry Medium 16223718
2007 The hPrp19 core complex normally includes Cdc5L, Plrg1, and Spf27; upon DNA damage, hPrp19 forms a ubiquitylated oligomeric species that fails to interact with either Cdc5L or Plrg1, indicating that DNA damage induces structural alterations that disrupt the PLRG1-containing core complex. SDS-PAGE under non-reducing conditions, co-immunoprecipitation, chromatin fractionation after DNA damage treatment Biochemical and biophysical research communications Medium 17276391
2009 PLRG1 is required for S-phase progression and suppression of apoptosis in vivo. PLRG1-deficient MEFs fail to progress through S phase and show increased apoptosis that is p53-dependent; PLRG1 deficiency causes enhanced p53 phosphorylation/stabilization and increased γ-H2AX, indicating an activated DNA damage response. PLRG1 is also required for nuclear retention of its binding partner CDC5L. Conditional knockout mice (heart- and neuron-specific), PLRG1-deficient MEFs, BrdU/FACS cell-cycle analysis, immunofluorescence for γ-H2AX, p53 knockdown rescue in MEFs and zebrafish, subcellular fractionation for CDC5L localization Molecular and cellular biology High 19307306
2009 PLRG1 is a core component of the Prp19/Pso4–Cdc5L–Plrg1–Spf27 complex; Cdc5L within this complex interacts physically with ATR kinase and is required for ATR-mediated S-phase checkpoint signaling (Chk1, Rad17, FancD2 activation). PLRG1's role is inferred through its membership in the Cdc5L complex that mediates this checkpoint. Co-immunoprecipitation (Cdc5L–ATR), siRNA depletion of Cdc5L, checkpoint kinase activation assays, deletion mapping of ATR-binding region in Cdc5L EMBO reports Low 19633697
2010 PLRG1 directly interacts with CDC5L in vivo; a central region of hnRNP-M mediates direct interaction with both CDC5L and PLRG1. This interaction is inhibited during heat-shock stress. An hnRNP-M mutant lacking the CDC5L/PLRG1 interaction domain cannot modulate alternative 5′ and 3′ splice site choice, placing PLRG1 in the pathway of alternative splicing regulation via hnRNP-M. Co-immunoprecipitation in vivo, domain mapping by deletion mutants, adeno-E1A minigene alternative splicing assay EMBO reports Medium 20467437
2014 PLRG1 (as part of the PSO4 core complex) is required for efficient recruitment of ATRIP to DNA damage sites and subsequent CHK1 activation and RPA2 phosphorylation; PLRG1 colocalizes with RPA at damage sites. Both the RPA1-binding ability of BCAS2 and the E3 ligase activity of PSO4 within the PLRG1-containing complex are required for these functions. siRNA depletion of complex subunits, immunofluorescence colocalization, co-immunoprecipitation of PLRG1-complex with RPA, in vitro ATR activation assays The Journal of biological chemistry Medium 24443570
2018 PLRG1 is essential for activation of the Prp19 (NTC) E3 ubiquitin ligase. Prp19 is autoinhibited on its own; stepwise assembly of SPF27, CDC5L, and PLRG1 onto the Prp19 tetramer enables ubiquitin ligation activity. Cross-linking/MS and functional assays defined the communication between PLRG1 and Prp19 that enables E3 activity, and crystal structure revealed the autoinhibition mechanism. X-ray crystallography of Prp19, mutational analysis of autoinhibition, stepwise reconstitution of NTC core, in vitro ubiquitin ligation assay, protein-protein crosslinking coupled to mass spectrometry Molecular cell High 29547724
2020 The crystal structure of the WD40 domain of human PLRG1 was solved by X-ray crystallography. Comparison with cryo-EM structures of PLRG1 within the spliceosome showed that two loops of the WD40 domain become resolved upon binding to other splicing factors, revealing dynamic conformational changes during spliceosome assembly. X-ray crystallography (apo WD40 domain), comparison with cryo-EM spliceosome structures Biochemical and biophysical research communications Medium 33239170
2021 USP42 (a deubiquitylase) directs the integration of PLRG1 into nuclear speckles (SC35-positive) in a phase-separation-dependent manner; depletion of USP42 displaces PLRG1 from nuclear speckles and deregulates mRNA splicing events phenocopying PLRG1 repression, placing USP42-mediated deubiquitylation upstream of PLRG1 nuclear speckle localization and splicing function. Immunofluorescence colocalization, USP42 siRNA knockdown, mRNA splicing assays, phase separation assays, subcellular fractionation Cell death and differentiation Medium 33731873
2022 DHX37 interacts with PLRG1 and together they co-occupy the promoter and superenhancer elements of cyclin D1 (CCND1) to transcriptionally activate CCND1 expression, promoting liver cancer cell proliferation. This reveals a non-canonical transcriptional/epigenomic function for PLRG1 beyond splicing. Co-immunoprecipitation (DHX37–PLRG1), ChIP-seq epigenomic profiling of DHX37-knockdown cells, ChIP showing co-occupancy at CCND1 promoter/superenhancer, siRNA knockdown proliferation assays Cancer research Medium 35290436
2023 PLRG1 knockdown in cancer cells (but not normal cells) causes mitotic arrest, microtubule instability, ER stress, autophagy accumulation, DNA damage, and ultimately apoptosis; in normal cells PLRG1 depletion induces G1 arrest as a self-protective mechanism, distinguishing tumor-specific from normal cell responses to PLRG1 loss. siRNA knockdown, cell-cycle FACS analysis, immunofluorescence for microtubule stability and DNA damage markers (γ-H2AX), apoptosis assays BMB reports Medium 37817442
2024 YBX1 directly binds to the PLRG1 promoter and transcriptionally activates PLRG1 expression; overexpression of YBX1 upregulates PLRG1 and promotes EMT (increased N-cadherin, Snail, migration, invasion) in HCC cells, and these effects are abolished by PLRG1 knockdown, placing PLRG1 downstream of YBX1 in the EMT pathway. Chromatin immunoprecipitation (ChIP) of YBX1 at PLRG1 promoter, luciferase reporter assay, siRNA knockdown of PLRG1, YBX1 overexpression, EMT marker immunoblotting, migration/invasion assays Medical oncology Medium 39400789

Source papers

Stage 0 corpus · 28 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2005 The Pso4 mRNA splicing and DNA repair complex interacts with WRN for processing of DNA interstrand cross-links. The Journal of biological chemistry 112 16223718
2009 Cdc5L interacts with ATR and is required for the S-phase cell-cycle checkpoint. EMBO reports 83 19633697
2010 Direct interaction between hnRNP-M and CDC5L/PLRG1 proteins affects alternative splice site choice. EMBO reports 59 20467437
2007 The Prp19/Pso4 core complex undergoes ubiquitylation and structural alterations in response to DNA damage. Biochemical and biophysical research communications 58 17276391
2021 USP42 drives nuclear speckle mRNA splicing via directing dynamic phase separation to promote tumorigenesis. Cell death and differentiation 57 33731873
2014 The PSO4 protein complex associates with replication protein A (RPA) and modulates the activation of ataxia telangiectasia-mutated and Rad3-related (ATR). The Journal of biological chemistry 51 24443570
2009 PLRG1 is an essential regulator of cell proliferation and apoptosis during vertebrate development and tissue homeostasis. Molecular and cellular biology 51 19307306
2001 A direct interaction between the carboxyl-terminal region of CDC5L and the WD40 domain of PLRG1 is essential for pre-mRNA splicing. The Journal of biological chemistry 48 11544257
2005 Blue light negatively regulates the sexual filamentation via the Cwc1 and Cwc2 proteins in Cryptococcus neoformans. Molecular microbiology 47 15813738
2017 Whole exome sequencing in 342 congenital cardiac left sided lesion cases reveals extensive genetic heterogeneity and complex inheritance patterns. Genome medicine 40 29089047
2018 Prp19/Pso4 Is an Autoinhibited Ubiquitin Ligase Activated by Stepwise Assembly of Three Splicing Factors. Molecular cell 37 29547724
2020 Leucine-rich α2-glycoprotein-1 upregulation in plasma and kidney of patients with lupus nephritis. BMC nephrology 34 32252660
2022 RNA Helicase DHX37 Facilitates Liver Cancer Progression by Cooperating with PLRG1 to Drive Superenhancer-Mediated Transcription of Cyclin D1. Cancer research 27 35290436
2012 BCAS2 is essential for Drosophila viability and functions in pre-mRNA splicing. RNA (New York, N.Y.) 23 23249746
2003 Identification of peptide inhibitors of pre-mRNA splicing derived from the essential interaction domains of CDC5L and PLRG1. Nucleic acids research 21 14576297
2010 Mating differentiation in Cryptococcus neoformans is negatively regulated by the Crk1 protein kinase. Fungal genetics and biology : FG & B 15 21111055
1994 Restoration of pathogenicity of a penetration-deficient mutant of Collectotrichum lagenarium by DNA complementation. Current genetics 14 8082164
2008 A screening for suppressor mutants reveals components involved in the blue light-inhibited sexual filamentation in Cryptococcus neoformans. Fungal genetics and biology : FG & B 12 18996495
2011 Cryptococcus neoformans mediator protein Ssn8 negatively regulates diverse physiological processes and is required for virulence. PloS one 11 21559476
2022 Investigation on the cellular mechanism of Prunetin evidenced through next generation sequencing and bioinformatic approaches against gastric cancer. Scientific reports 9 35831348
2023 Elevated level of PLRG1 is critical for the proliferation and maintenance of genome stability of tumor cells. BMB reports 6 37817442
2024 Association of major candidate protein biomarkers and long-term diabetic kidney disease progression among Asians with young-onset type 2 diabetes mellitus. Diabetes research and clinical practice 5 39142520
2015 Application of serex-analysis for identification of human colon cancer antigens. Experimental oncology 5 26422100
2024 YBX1 promotes epithelial-mesenchymal transition in hepatocellular carcinoma via transcriptional regulation of PLRG1. Medical oncology (Northwood, London, England) 4 39400789
2020 Crystal structure of the WD40 domain of human PLRG1. Biochemical and biophysical research communications 4 33239170
2024 Comparative study of transcriptomic alterations in sepsis-induced acute liver injury: Deciphering the role of alternative splicing in mouse models. International immunopharmacology 1 39719759
2026 RNA-sequencing based gene variants observed in patients with hyperlipidemia and premature coronary heart disease: A preliminary study. Biochemistry and biophysics reports 0 41631214
2025 Discovering periodontitis biomarkers and therapeutic targets through bioinformatics and ensemble learning analysis. Scientific reports 0 41044121

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