Affinage

PABPC1L

Polyadenylate-binding protein 1-like · UniProt Q4VXU2

Length
619 aa
Mass
68.9 kDa
Annotated
2026-06-10
21 papers in source corpus 12 papers cited in narrative 12 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

PABPC1L (ePAB/EPAB) is the predominant cytoplasmic poly(A)-binding protein of oocytes and early embryos, where it controls maternal mRNA fate by binding and stabilizing poly(A) tails against deadenylation and licensing their translation (PMID:11274061, PMID:22621333). It acts within the cytoplasmic polyadenylation machinery: it associates transiently with CPEB before binding the elongated poly(A) tail to protect it, and bridges to eIF4G to drive translation initiation of CPEB-bound mRNAs, with its release from CPEB controlled by RINGO/cdk1-mediated CPEB phosphorylation (PMID:17938241). Phosphorylation of PABPC1L itself at a four-residue cluster is required for cytoplasmic polyadenylation and oocyte maturation but is dispensable for its intrinsic translation-promoting activity (PMID:22497250). Through these activities PABPC1L drives translational activation of maternal transcripts such as Ccnb1 and Dazl and is essential for oocyte maturation, cumulus expansion, granulosa/cumulus cell responsiveness to LH and EGF signaling, and female fertility, such that its loss causes infertility in mice (PMID:22621333, PMID:26492470). Loss-of-function and missense variants in human PABPC1L cause oocyte maturation arrest and female infertility, acting through reduced protein abundance, altered localization, impaired mRNA binding, and dysregulation of the Mos-MAPK pathway, with knock-in mice phenocopying the human defect and human MOS mRNA recapitulating the phenotype (PMID:37052235, PMID:37723834). In somatic cancer contexts, PABPC1L stabilizes JAK2 mRNA to activate JAK2-STAT1 signaling and induce IDO1-driven tryptophan catabolism and immune suppression, and its transcription is induced by FOXM1 (PMID:38382068, PMID:41985819).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2001 High

    Established the biochemical identity and core activity of PABPC1L by showing it is the dominant oocyte poly(A)-binding protein that stabilizes poly(A) tails, answering whether a distinct PABP governs maternal mRNA stability.

    Evidence ARE affinity purification and immunodepletion/add-back in Xenopus egg extracts with in vitro deadenylation assays

    PMID:11274061

    Open questions at the time
    • Did not define the in vivo mRNA targets
    • Did not connect poly(A) protection to translational output
  2. 2007 High

    Placed PABPC1L within the cytoplasmic polyadenylation pathway, showing how it transitions from CPEB association to poly(A)-tail binding and recruits eIF4G, explaining the coupling of polyadenylation to translation.

    Evidence Reciprocal co-immunoprecipitation and in vitro binding assays in Xenopus oocytes with RINGO/cdk1 epistasis

    PMID:17938241

    Open questions at the time
    • Structural basis of the CPEB-to-poly(A) handoff not resolved
    • Quantitative kinetics of the eIF4G recruitment step not defined
  3. 2012 High

    Identified PABPC1L's own phosphorylation as a regulatory switch, separating its polyadenylation/maturation function from its intrinsic translation-promoting activity.

    Evidence Site-directed mutagenesis of a four-residue cluster with Xenopus oocyte maturation and phosphorylation assays

    PMID:22497250

    Open questions at the time
    • Kinase responsible for the four-residue cluster not identified
    • Effect of phosphorylation on RNA binding not measured directly
  4. 2012 High

    Demonstrated in mammals that PABPC1L is genetically required for translational activation of stored maternal mRNAs and for female fertility, with rescue failure pinpointing a requirement before the GV stage.

    Evidence Epab-knockout mice with RT-PCR translational readouts (Ccnb1, Dazl) and GV-oocyte mRNA microinjection rescue

    PMID:22621333

    Open questions at the time
    • Earliest oogenic stage requiring EPAB not mapped
    • Full set of EPAB-dependent maternal transcripts not catalogued
  5. 2015 High

    Extended PABPC1L's role from cell-autonomous oocyte function to bidirectional oocyte-cumulus communication, showing it is needed for granulosa/cumulus cell responsiveness to LH and EGF.

    Evidence Oocytectomized cumulus complex coculture and western blotting for MEK/ERK/p90RSK/EGFR phosphorylation in Epab-knockout mice

    PMID:26492470

    Open questions at the time
    • Identity of the oocyte-derived signaling factor under EPAB control not defined
    • Mechanism linking maternal mRNA translation to somatic-cell signaling competence unresolved
  6. 2023 High

    Translated the model to human disease, establishing PABPC1L variants as a cause of oocyte maturation arrest and female infertility and implicating Mos-MAPK dysregulation as the downstream effector.

    Evidence Human exome sequencing, in vitro functional studies, Pabpc1l knock-in mice, RNA-seq, and MOS mRNA microinjection epistasis

    PMID:37052235 PMID:37723834

    Open questions at the time
    • How variant-induced loss of mRNA binding produces Mos-MAPK hyperactivation not mechanistically connected
    • Genotype-phenotype relationship across variant classes not established
  7. 2024 Medium

    Identified a somatic oncogenic function whereby PABPC1L stabilizes JAK2 mRNA to drive JAK2-STAT1-IDO1 signaling and immune evasion, repositioning the maternal PABP as a tumor immune modulator.

    Evidence Knockdown/overexpression, mRNA stability assays, JAK2-STAT1 western blotting, and patient-derived xenografts with anti-PD-1

    PMID:38382068

    Open questions at the time
    • Direct PABPC1L binding to JAK2 mRNA not structurally demonstrated
    • Single-lab finding without reciprocal validation of the positive feedback loop
  8. 2026 Medium

    Placed PABPC1L downstream of a transcriptional activator, identifying FOXM1 as a driver of PABPC1L expression that feeds the JAK2-STAT1-IDO1 axis in cancer.

    Evidence CETSA, FOXM1 site-directed mutagenesis, luciferase transcriptional activation, and inhibitor rescue in nasopharyngeal carcinoma cells

    PMID:41985819

    Open questions at the time
    • Direct FOXM1 occupancy at the PABPC1L promoter not shown by ChIP
    • Generality of the FOXM1-PABPC1L axis beyond the tested cancer context not established

Open questions

Synthesis pass · forward-looking unresolved questions
  • How a single poly(A)-binding protein switches between its maternal translational-control program and its somatic mRNA-stabilizing oncogenic role, and what determines target selection in each context, remains unresolved.
  • No unified model linking oocyte and cancer functions
  • Target-mRNA selectivity rules not defined
  • No structural data on PABPC1L-mRNA or PABPC1L-partner complexes

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003723 RNA binding 3 GO:0045182 translation regulator activity 3 GO:0140313 molecular sequestering activity 1
Localization
GO:0005829 cytosol 3
Pathway
R-HSA-8953854 Metabolism of RNA 3 R-HSA-1474165 Reproduction 2 R-HSA-162582 Signal Transduction 2
Partners
CPEBEIF4GFOXM1JAK2
Complex memberships
cytoplasmic polyadenylation complex (CPEB-associated)

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2001 ePAB (PABPC1L) was purified from Xenopus activated egg extracts by ARE affinity selection and identified as the predominant poly(A)-binding protein in stage VI oocytes and early development. Immunodepletion of ePAB increases the rate of both ARE-mediated and default deadenylation in vitro, while addition of excess ePAB inhibits deadenylation, demonstrating that ePAB stabilizes poly(A) tails and regulates mRNA deadenylation. ARE affinity purification, immunodepletion from Xenopus egg extracts, in vitro deadenylation assay Genes & development High 11274061
2007 ePAB transiently associates with the cytoplasmic polyadenylation complex by initially interacting with CPEB; after polyadenylation, ePAB binds the poly(A) tail to protect it from deadenylating enzymes. ePAB dissociation from CPEB is regulated by RINGO-activated cdk1, which phosphorylates CPEB. Poly(A)-bound ePAB also interacts with eIF4G to initiate translation of CPEB-bound mRNAs. Co-immunoprecipitation, in vitro binding assays, Xenopus oocyte biochemistry Genes & development High 17938241
2012 ePAB (PABPC1L) is a phosphoprotein in Xenopus oocytes; phosphorylation at a four-residue cluster is required for oocyte maturation and cytoplasmic polyadenylation but not for ePAB's inherent ability to promote translation, as shown by mutation analysis. Site-directed mutagenesis, Xenopus oocyte maturation assay, phosphorylation analysis The Biochemical journal High 22497250
2012 EPAB (PABPC1L) is required in mice for translational activation of maternally stored mRNAs during oocyte maturation (including Ccnb1 and Dazl mRNAs). Epab-knockout female mice are infertile, fail to produce mature oocytes, and show impaired cumulus expansion and 8-fold decreased ovulation. Microinjection of Epab mRNA into Epab(-/-) GV oocytes did not rescue maturation, indicating EPAB is required for earlier stages of oogenesis. Epab knockout mouse model, RT-PCR for translational activation, mRNA microinjection rescue experiment The Biochemical journal High 22621333
2015 EPAB, expressed in oocytes, is required for granulosa cells (GCs) and cumulus cells (CCs) to become responsive to LH and EGF signaling. Epab(-/-) GCs show decreased phosphorylation of MEK1/2, ERK1/2, p90RSK, and EGF receptor in response to LH and EGF. Coculture experiments showed that both Epab(-/-) oocytes (impaired signal sending) and Epab(-/-) CCs (impaired signal receiving) fail to support cumulus expansion. Oocytectomized cumulus complex coculture system, western blotting for phosphoproteins, Epab(-/-) mouse model Endocrinology High 26492470
2023 Compound heterozygous and homozygous variants in PABPC1L cause oocyte maturation arrest and female infertility in humans. In vitro studies showed that pathogenic variants lead to truncated proteins, reduced protein abundance, altered cytoplasmic localization, and decreased mRNA-binding capacity. In vivo, Pabpc1l knock-in mice are infertile. RNA-sequencing revealed abnormal activation of the Mos-MAPK pathway in KI zygotes, and injection of human MOS mRNA into WT zygotes recapitulated the KI phenotype. Human exome sequencing, in vitro functional studies (protein truncation, localization, mRNA-binding assay), Pabpc1l knock-in mice, RNA-seq, mRNA microinjection EMBO molecular medicine High 37052235
2024 PABPC1L enhances stability of JAK2 mRNA, leading to increased JAK2-STAT1 signaling that induces IDO1 expression, promoting tryptophan catabolism and immune suppression in renal cell carcinoma. PABPC1L-induced JAK2-STAT1 activation creates a positive feedback loop to promote PABPC1L transcription. Loss of PABPC1L reduces IDO1 expression, mitigates cytotoxic T-cell suppression, and enhances anti-PD-1 responsiveness in patient-derived xenograft models. PABPC1L knockdown/overexpression, mRNA stability assay, western blotting for JAK2-STAT1 signaling, patient-derived xenograft models Cancer research Medium 38382068
2023 A homozygous missense mutation (p.R179Q) and compound heterozygous mutations (p.R265W; p.Q401*) in PABPC1L result in nonfunctional protein, impaired chromatin configuration and transcriptional silencing in GV oocytes, and significantly decreased binding capacity of mutant PABPC1L to mRNAs involved in oocyte maturation and early embryonic development. Exome sequencing, functional protein studies, mRNA-binding assay, chromatin configuration analysis in GV oocytes Clinical genetics Medium 37723834
2024 A homozygous missense variant (p.Ala346Val) located in the conserved fourth RNA recognition motif (RRM4) of PABPC1L/EPAB causes increased protein instability and proteolysis, as demonstrated by transfection of HEK293T cells and in silico 3D modeling of structural changes. Transfection of HEK293T cells, protein stability assay, in silico 3D structural modeling Journal of assisted reproduction and genetics Low 38177974
2025 Five novel PABPC1L missense and nonsense variants cause downregulation of PABPC1L protein expression; a nonsense variant (p.Lys95*) alters cytoplasmic localization of PABPC1L. Missense variants impair protein stability as shown by cycloheximide chase assay and 3D molecular modeling. Western blotting in HEK293T cells, immunofluorescence in HeLa cells, cycloheximide chase assay, 3D molecular modeling Journal of assisted reproduction and genetics Low 41275460
2019 PABPC1L depletion in HT-29 colorectal cancer cells inhibits proliferation, invasion, and migration, associated with reduced phosphorylation of AKT and PI3K, indicating PABPC1L promotes cell proliferation and migration via the PI3K-AKT pathway. siRNA knockdown, CCK-8/clone formation/wound-healing/Transwell assays, western blotting for p-AKT and p-PI3K Oncology letters Low 30867782
2026 FOXM1 acts as a transcriptional activator of PABPC1L; downregulation of FOXM1 by rAnguillin suppresses PABPC1L expression, which inactivates JAK2-STAT1 signaling and IDO1, disrupting tryptophan metabolism in nasopharyngeal carcinoma cells. CETSA, site-directed mutagenesis of FOXM1, luciferase/transcriptional activation assay, inhibitor rescue experiments International journal of biological macromolecules Medium 41985819

Source papers

Stage 0 corpus · 21 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2001 A novel embryonic poly(A) binding protein, ePAB, regulates mRNA deadenylation in Xenopus egg extracts. Genes & development 105 11274061
2007 RINGO/cdk1 and CPEB mediate poly(A) tail stabilization and translational regulation by ePAB. Genes & development 95 17938241
2012 Embryonic poly(A)-binding protein (EPAB) is required for oocyte maturation and female fertility in mice. The Biochemical journal 75 22621333
2005 An embryonic poly(A)-binding protein (ePAB) is expressed in mouse oocytes and early preimplantation embryos. Proceedings of the National Academy of Sciences of the United States of America 75 15630085
2008 Identification and characterization of human embryonic poly(A) binding protein (EPAB). Molecular human reproduction 42 18716053
2012 Epab and Pabpc1 are differentially expressed during male germ cell development. Reproductive sciences (Thousand Oaks, Calif.) 33 22814100
2024 PABPC1L Induces IDO1 to Promote Tryptophan Metabolism and Immune Suppression in Renal Cell Carcinoma. Cancer research 29 38382068
2019 PABPC1L depletion inhibits proliferation and migration via blockage of AKT pathway in human colorectal cancer cells. Oncology letters 28 30867782
2015 Embryonic Poly(A)-Binding Protein (EPAB) Is Required for Granulosa Cell EGF Signaling and Cumulus Expansion in Female Mice. Endocrinology 26 26492470
2012 Embryonic poly(A)-binding protein (ePAB) phosphorylation is required for Xenopus oocyte maturation. The Biochemical journal 26 22497250
2019 Translational activation of maternally derived mRNAs in oocytes and early embryos and the role of embryonic poly(A) binding protein (EPAB). Biology of reproduction 21 30806655
2016 The poly(A)-binding protein genes, EPAB, PABPC1, and PABPC3 are differentially expressed in infertile men with non-obstructive azoospermia. Journal of assisted reproduction and genetics 19 26843391
2023 Bi-allelic pathogenic variants in PABPC1L cause oocyte maturation arrest and female infertility. EMBO molecular medicine 18 37052235
2014 Epab and Pabpc1 are differentially expressed in the postnatal mouse ovaries. Journal of assisted reproduction and genetics 18 25370180
2013 Human embryonic poly(A)-binding protein (EPAB) alternative splicing is differentially regulated in human oocytes and embryos. Molecular human reproduction 14 24002949
2008 Isolation of the human ePAB and ePABP2 cDNAs and analysis of the expression patterns. Journal of assisted reproduction and genetics 10 18483763
2023 Identification of nonfunctional PABPC1L causing oocyte maturation abnormalities and early embryonic arrest in female primary infertility. Clinical genetics 8 37723834
2024 Pathogenic missense variation in PABPC1L/EPAB causes female infertility due to oocyte maturation arrest at the germinal vesicle stage. Journal of assisted reproduction and genetics 3 38177974
2026 A novel recombinant peptide, rAnguillin, induces ferroptosis in nasopharyngeal carcinoma by promoting FOXM1 degradation and disrupting the FOXM1-PABPC1L-tryptophan metabolism axis. International journal of biological macromolecules 0 41985819
2025 Novel variants in PABPC1L cause female infertility due to oocyte maturation defects. Journal of assisted reproduction and genetics 0 41275460
2025 Coordinated upregulation of PABPC1L and SNHG lncRNAs defines a tumor-specific expression module in colorectal cancer: evidence from paired tumor-normal expression profiling. Biochemistry and biophysics reports 0 41357316

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