Affinage

PDCD2

uS5 assembly chaperone PDCD2 · UniProt Q16342

Length
344 aa
Mass
38.6 kDa
Annotated
2026-04-29
29 papers in source corpus 15 papers cited in narrative 15 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PDCD2 is a dedicated co-translational chaperone for the 40S ribosomal protein uS5 (RPS2), essential for ribosome biogenesis, stem cell maintenance, and hematopoiesis. PDCD2 binds uS5 co-translationally via a conserved FxxGFG motif in the uS5 N-terminus, escorts uS5 from the cytoplasm to nuclear ribosome assembly sites, and is required for proper 40S subunit synthesis; loss of PDCD2 phenocopies uS5 deficiency and causes rRNA processing defects (PMID:33245768, PMID:41933732, PMID:40208938). Through its MYND domain, PDCD2 also interacts with HCF-1 and N-CoR/mSin3A corepressor complexes, and its transcription is directly repressed by BCL6 (PMID:12149646, PMID:11854457). PDCD2 is essential for mouse embryonic development and ESC maintenance, with its loss triggering p53-dependent G1 arrest, and biallelic loss-of-function variants in PDCD2 cause a human ribosomopathy (PMID:20813103, PMID:25150276, PMID:40208938).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2002 High

    Establishing that PDCD2 is a MYND-domain-containing corepressor-associated protein resolved its molecular identity: PDCD2 interacts with HCF-1 via its MYND domain and associates with N-CoR/mSin3A corepressor complexes, placing it in transcriptional regulatory machinery.

    Evidence Co-immunoprecipitation, domain mapping, and temperature-sensitive complementation in human cells

    PMID:12149646

    Open questions at the time
    • Whether the HCF-1/N-CoR interaction mediates specific gene repression programs is unknown
    • Endogenous target genes regulated through this complex remain uncharacterized
    • Structural basis of MYND-HCF-1 interaction not resolved
  2. 2002 High

    Identifying BCL6 as a direct transcriptional repressor of PDCD2 revealed how PDCD2 levels are controlled in germinal center B cells, linking PDCD2 regulation to lymphoma biology.

    Evidence Subtractive hybridization, VP16-BCL6 competition transfection, ChIP, and siRNA knockdown of BCL6 with protein-level readout

    PMID:11854457 PMID:17468402

    Open questions at the time
    • Whether BCL6-mediated repression of PDCD2 is the functional driver of germinal center apoptosis regulation
    • Other transcription factors regulating PDCD2 expression are unknown
  3. 2007 High

    Demonstrating that the Drosophila ortholog Zfrp8 is essential for hematopoietic stem cell maintenance established that PDCD2's role in stem cell biology is evolutionarily conserved and linked to cell-cycle regulation.

    Evidence Drosophila loss-of-function mutants with lymph gland hyperplasia and altered gamma-Tubulin/Cyclin B distribution

    PMID:17522156

    Open questions at the time
    • Molecular mechanism connecting PDCD2 to centrosome function and cell-cycle regulators was unclear
    • Whether the hematopoietic phenotype reflects a ribosome biogenesis defect was not tested
  4. 2010 High

    Mouse knockout studies proved PDCD2 is essential for early mammalian development and embryonic stem cell self-renewal, with conditional deletion later revealing p53-dependent G1 arrest as the proximate cellular consequence of PDCD2 loss.

    Evidence Pdcd2 knockout mice (peri-implantation lethality, ICM outgrowth failure), tamoxifen-inducible conditional knockout in MEFs/ESCs with flow cytometry and p53 pathway analysis

    PMID:20813103 PMID:25150276

    Open questions at the time
    • Whether p53 activation is a direct effect of PDCD2 loss or secondary to ribosome biogenesis stress was unresolved
    • The upstream trigger for p53 stabilization was not identified
  5. 2012 Medium

    Zebrafish studies placed PDCD2 in a hematopoietic differentiation pathway upstream of runx1 and Jak/Stat signaling, demonstrating vertebrate conservation of its stem/progenitor cell role.

    Evidence Morpholino knockdown in zebrafish with epistasis (runx1 rescue, Jak/Stat inhibition) and colony-forming assays

    PMID:22800338

    Open questions at the time
    • Morpholino-based approach lacks genetic confirmation
    • Mechanism linking PDCD2 to runx1 regulation not established
    • Whether hematopoietic defect reflects ribosome biogenesis impairment was not tested
  6. 2014 High

    Demonstrating that Zfrp8/PDCD2 forms a complex with the piRNA pathway component Maelstrom and that human PDCD2 fully rescues the Drosophila mutant extended functional conservation to germline stem cells and suggested a role in RNA/RNP regulation.

    Evidence Drosophila genetics, human PDCD2 rescue of Zfrp8 mutant, co-immunoprecipitation of Zfrp8-Maelstrom complex

    PMID:24381196

    Open questions at the time
    • Whether the Maelstrom interaction is related to or independent of ribosome biogenesis function
    • Relevance of piRNA pathway connection to mammalian PDCD2 function unknown
  7. 2016 High

    Identifying a direct interaction between Zfrp8/PDCD2 and the 40S ribosomal protein uS5 (RpS2), and showing that PDCD2 depletion alters ribosomal subunit protein distribution, provided the first evidence that PDCD2 functions in ribosome biogenesis.

    Evidence Co-immunoprecipitation, fluorescent ribosomal protein distribution assay, RNA immunoprecipitation, and knockdown in Drosophila

    PMID:26807849

    Open questions at the time
    • Whether PDCD2 acts as a chaperone or assembly factor was unclear
    • Co-translational nature of the interaction was not established
  8. 2020 High

    Reconstitution of the PDCD2-uS5 chaperoning pathway in human cells established that PDCD2 acts as a dedicated co-translational chaperone for uS5, escorting it to nuclear assembly sites and being required for 40S subunit biogenesis—unifying the ribosome biogenesis, p53 activation, and stem cell phenotypes.

    Evidence Quantitative AP-MS, co-translational complex assembly assay, ribosome profiling, loss-of-function knockdown, nuclear/cytoplasmic fractionation in human cells

    PMID:33245768

    Open questions at the time
    • Structural details of the PDCD2-uS5 interface were not resolved
    • Whether PDCD2 has additional chaperone clients was not addressed
  9. 2025 High

    Discovery of biallelic PDCD2 loss-of-function variants in patients with developmental abnormalities and impaired rRNA processing established PDCD2 deficiency as a human ribosomopathy, validating the chaperone mechanism in vivo.

    Evidence Exome sequencing, patient-derived fibroblast biochemistry (Co-IP, rRNA processing assay), Xenopus knockdown with phenotypic rescue

    PMID:40208938

    Open questions at the time
    • Full clinical spectrum of PDCD2-associated ribosomopathy not yet defined
    • Whether residual PDCD2 function determines disease severity is unknown
  10. 2026 High

    Mapping the minimal interaction interface to a 30-amino-acid uS5 N-terminal region containing a conserved FxxGFG motif, and demonstrating that a peptide disrupting this interaction kills cancer cells, defined the structural basis and therapeutic vulnerability of the PDCD2-uS5 axis.

    Evidence Affinity purification, mutagenesis of FxxGFG motif, split-luciferase biosensor, inhibitory peptide viability assay

    PMID:41933732

    Open questions at the time
    • Atomic-resolution structure of the PDCD2-uS5 complex is not yet available
    • Selectivity and pharmacokinetics of peptide inhibitor in vivo unknown
    • Whether disrupting PDCD2-uS5 interaction differentially affects cancer vs. normal cells not established

Open questions

Synthesis pass · forward-looking unresolved questions
  • The relationship between PDCD2's ribosome biogenesis function and its interactions with HCF-1/corepressor machinery and the piRNA pathway remains mechanistically unresolved—whether these represent independent functions or are integrated through a common RNP quality control mechanism is unknown.
  • No structural model of full-length PDCD2 or its complexes exists
  • Whether PDCD2 chaperones ribosomal proteins beyond uS5 has not been tested
  • The mechanistic link between ribosome biogenesis defect and p53-dependent arrest (nucleolar stress vs. other mechanism) is not formally demonstrated

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0044183 protein folding chaperone 3 GO:0140110 transcription regulator activity 3 GO:0005198 structural molecule activity 2
Localization
GO:0005634 nucleus 2 GO:0005829 cytosol 2
Pathway
R-HSA-392499 Metabolism of proteins 4 R-HSA-1640170 Cell Cycle 2 R-HSA-1643685 Disease 1
Partners
BCL6HCF1MAELNCOR1RPS2SIN3A
Complex memberships
N-CoR/mSin3A corepressor complexPDCD2-uS5 chaperone complex

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2002 PDCD2 protein interacts with the C-terminal WYF domain of HCF-1 via the MYND domain of PDCD2; this interaction is conserved between human HCF-1, HCF-2, and C. elegans HCF. Overexpression of PDCD2, which associates with N-CoR/mSin3A corepressor complexes, suppresses HCF-1 complementation of a temperature-sensitive lesion, and overexpression of interfering domains of either protein enhances complementation. Co-immunoprecipitation, domain mapping, temperature-sensitive complementation assay, overexpression of truncation mutants Oncogene High 12149646
2002 BCL6 represses transcription of the PDCD2 gene; BCL6 zinc fingers bind the PDCD2 promoter in a sequence-specific manner, and competing with endogenous BCL6 using a VP16-BCL6 fusion protein de-represses PDCD2 expression. Subtractive hybridization, VP16-BCL6 competition transfection, immunohistochemistry showing inverse BCL6/PDCD2 expression in germinal centers Proceedings of the National Academy of Sciences of the United States of America High 11854457 17468402
2007 BCL6 directly binds the PDCD2 promoter to repress its transcription; siRNA knockdown of BCL6 in a human B-cell lymphoma line increases PDCD2 protein expression, confirming direct transcriptional repression. ChIP/promoter binding assay, siRNA knockdown, Western blotting Proceedings of the National Academy of Sciences of the United States of America High 17468402
2007 Drosophila Zfrp8 (PDCD2 ortholog) is essential for hematopoietic stem cell maintenance; loss-of-function mutants show lymph gland hyperplasia from increased proliferation of undifferentiated hemocytes. Genetic interactions with l(1)dd4/Dgrip91 (gamma-tubulin anchoring) and Cdc27/APC component place Zfrp8 in a pathway regulating cell-cycle components through centrosome function. The subcellular distribution of gamma-Tubulin and Cyclin B is altered in mutants. Drosophila genetics (loss-of-function mutants), dominant enhancement genetic interaction, subcellular localization of gamma-Tubulin and Cyclin B Development (Cambridge, England) High 17522156
2010 Transfection of a PDCD2-expressing construct induces apoptosis in human cell lines through activation of the caspase cascade; caspase inhibitors block this effect. Knockdown of PDCD2 by siRNA in a Burkitt lymphoma cell line inhibits apoptosis. Transfection/overexpression, caspase inhibitor treatment, siRNA knockdown, Annexin V/flow cytometry Blood cells, molecules & diseases Medium 20605493
2010 PDCD2 is essential for inner cell mass development and embryonic stem cell maintenance; Pdcd2-/- mouse embryos fail to develop past implantation, Pdcd2-/- ICMs fail to outgrow in vitro, and Pdcd2-/- ESCs cannot be established without an ectopic transgene. PDCD2 levels decline upon ESC differentiation, indicating a role in maintaining the undifferentiated state. Mouse knockout, blastocyst outgrowth assay, ESC derivation attempts, retinoic acid/LIF withdrawal differentiation Developmental biology High 20813103
2014 Zfrp8/PDCD2 is required in both germline and follicle stem cells in the Drosophila ovary; human PDCD2 fully rescues the Zfrp8 mutant phenotype, demonstrating functional conservation. Zfrp8 forms a complex with piRNA pathway protein Maelstrom and controls its accumulation in the nuage; nuclear localization of Zfrp8 in germline stem cells is regulated by piRNA pathway genes. Drosophila genetics (loss-of-function), human PDCD2 rescue, co-immunoprecipitation (Zfrp8-Maelstrom complex), immunofluorescence localization Development (Cambridge, England) High 24381196
2014 Conditional knockout of PDCD2 (deletion of exon 2 containing the MYND domain) in mouse embryonic fibroblasts and ESCs causes G1-to-S phase cell cycle arrest, increased p53 protein levels, and upregulation of p53 target genes. The same phenotype is observed in PDCD2 knockout blastocysts. Tamoxifen-inducible conditional knockout, flow cytometry cell cycle analysis, Western blotting for p53, qPCR for p53 targets Biology open High 25150276
2016 Zfrp8/PDCD2 directly interacts with the 40S small ribosomal subunit protein RpS2 (uS5) and regulates the cytoplasmic levels of small ribosomal subunit components. Knockdown of Zfrp8/PDCD2 causes nuclear accumulation of specific mRNAs and TE transcripts, suggesting a role at late stages of ribosome assembly governing cytoplasmic localization and translation of specific mRNPs. Co-immunoprecipitation, fluorescently tagged ribosomal protein distribution assay, RNA immunoprecipitation, knockdown PloS one High 26807849
2020 Human PDCD2 acts as a dedicated ribosomal protein chaperone for the 40S ribosomal protein uS5 (RPS2); the PDCD2-uS5 complex is assembled co-translationally. Loss of PDCD2 leads to defects in 40S small ribosomal subunit synthesis phenocopying uS5 deficiency, reduced soluble uS5 protein accumulation, and impaired uS5 incorporation into the 40S subunit. PDCD2 accompanies uS5 from the cytoplasm to ribosome assembly sites in the nucleus. Quantitative proteomics (AP-MS), co-translational complex assembly assay, ribosome profiling, Western blotting, loss-of-function knockdown, nuclear/cytoplasmic fractionation Nucleic acids research High 33245768
2012 PDCD2 knockdown in zebrafish impairs hematopoietic stem cell emergence in the aorta-gonad-mesonephros, causes erythroid progenitor accumulation, and blocks terminal differentiation. Effects are cell-autonomous and p53-independent. Restoration of runx1 function and inhibition of Jak/Stat signaling rescue the hematopoietic defects, placing PDCD2 in a pathway upstream of runx1 and Jak/Stat in hematopoietic lineage determination. Morpholino knockdown in zebrafish, genetic epistasis (runx1 rescue, Jak/Stat inhibition), colony-forming assays, flow cytometry Stem cells and development Medium 22800338
2025 Biallelic loss-of-function variants in PDCD2 cause reduced PDCD2 protein levels, impaired PDCD2 binding to uS5, and altered ribosomal RNA processing in patient-derived fibroblasts and cell lines. Xenopus Pdcd2 knockdown recapitulates developmental edema and rRNA processing defects, establishing PDCD2-uS5 chaperone function as essential for ribosome biogenesis in vivo. Exome sequencing, patient-derived fibroblast biochemistry, Co-IP (PDCD2-uS5 binding), rRNA processing assay, Xenopus knockdown with phenotypic rescue Proceedings of the National Academy of Sciences of the United States of America High 40208938
2026 A stretch of 30 amino acids in the N-terminal region of uS5 is necessary and sufficient for interaction with PDCD2, and a conserved FxxGFG motif in uS5 mediates association with PDCD2 via hydrophobic interactions. An 11-amino acid uS5-derived peptide that inhibits the PDCD2-uS5 interaction impairs cancer cell viability, confirmed by a complementation-based biosensor monitoring the interaction in living cells. Affinity purification, structural modeling, mutagenesis (FxxGFG motif), split-luciferase complementation biosensor, peptide inhibitor assay, cell viability assay The Journal of biological chemistry High 41933732
2023 A chemical proteomics screen identified a small molecule degrader (compound 10e) of PDCD2; pharmacological degradation of PDCD2 in T lymphoblasts impairs cell cycle progression, confirming PDCD2 as a critical regulator of cell growth. Chemical proteomics (targeted protein degrader screen), PDCD2 degrader treatment, cell cycle analysis Angewandte Chemie (International ed. in English) Medium 37658265
2022 PDCD2 binds directly to andrographolide; this interaction leads to blockade of CDK mRNA nuclear export, reduced CDK protein expression, and tumor cell cycle arrest in vitro and in vivo. Proteome chip screening, RNA-binding protein immunoprecipitation for PDCD2, nuclear mRNA distribution analysis, in vivo tumor assay ACS pharmacology & translational science Medium 35837135

Source papers

Stage 0 corpus · 29 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2002 The human programmed cell death-2 (PDCD2) gene is a target of BCL6 repression: implications for a role of BCL6 in the down-regulation of apoptosis. Proceedings of the National Academy of Sciences of the United States of America 84 11854457
2007 Zfrp8, the Drosophila ortholog of PDCD2, functions in lymph gland development and controls cell proliferation. Development (Cambridge, England) 44 17522156
2002 PDCD2 is a negative regulator of HCF-1 (C1). Oncogene 42 12149646
2007 Repression of the PDCD2 gene by BCL6 and the implications for the pathogenesis of human B and T cell lymphomas. Proceedings of the National Academy of Sciences of the United States of America 30 17468402
1995 Isolation and mapping of a human gene (PDCD2) that is highly homologous to Rp8, a rat gene associated with programmed cell death. Cytogenetics and cell genetics 30 7606924
2010 PDCD2, a protein whose expression is repressed by BCL6, induces apoptosis in human cells by activation of the caspase cascade. Blood cells, molecules & diseases 28 20605493
2010 PDCD2 is essential for inner cell mass development and embryonic stem cell maintenance. Developmental biology 28 20813103
1993 SGP2, ubiquitin, 14K lectin and RP8 mRNAs are not induced in neuronal apoptosis. Neuroreport 26 8388743
2014 Zfrp8/PDCD2 is required in ovarian stem cells and interacts with the piRNA pathway machinery. Development (Cambridge, England) 22 24381196
2013 PDCD2 functions in cancer cell proliferation and predicts relapsed leukemia. Cancer biology & therapy 22 23760497
2020 PDCD2 functions as an evolutionarily conserved chaperone dedicated for the 40S ribosomal protein uS5 (RPS2). Nucleic acids research 21 33245768
1995 Cloning of mouse RP-8 cDNA and its expression during apoptosis of lymphoid and myeloid cells. DNA and cell biology 20 7880439
2019 PDCD2 sensitizes HepG2 cells to sorafenib by suppressing epithelial‑mesenchymal transition. Molecular medicine reports 17 30664177
2015 PDCD2 and NCoR1 as putative tumor suppressors in gastric gastrointestinal stromal tumors. Cellular oncology (Dordrecht, Netherlands) 17 26589942
2012 PDCD2 controls hematopoietic stem cell differentiation during development. Stem cells and development 17 22800338
1993 Exclusion of the involvement of all known retinitis pigmentosa loci in the disease present in a family of Irish origin provides evidence for a sixth autosomal dominant locus (RP8). Human molecular genetics 16 8364569
2019 Zinc finger protein RP-8, the Bombyx mori ortholog of programmed cell death 2, regulates cell proliferation. Developmental and comparative immunology 15 31730828
2016 Zfrp8/PDCD2 Interacts with RpS2 Connecting Ribosome Maturation and Gene-Specific Translation. PloS one 15 26807849
2014 miR-129-1-3p promote BGC-823 cell proliferation by targeting PDCD2. Anatomical record (Hoboken, N.J. : 2007) 12 25111461
2014 Conditional inactivation of PDCD2 induces p53 activation and cell cycle arrest. Biology open 10 25150276
2012 PDCD2 knockdown inhibits erythroid but not megakaryocytic lineage differentiation of human hematopoietic stem/progenitor cells. Experimental hematology 8 22922207
2005 Cloning of cDNAs with PDCD2(C) domain and their expressions during apoptosis of HEK293T cells. Molecular and cellular biochemistry 8 16311922
1995 Expression of the death-associated gene RP-8 in granule cell neurons undergoing postnatal cell death in the cerebellum of weaver mice. Brain research. Developmental brain research 6 7656429
2004 Comparative analysis of the PDCD2-TBP-PSMB1 region in vertebrates. Gene 5 15194198
2008 Overexpression of the PDCD2-like gene results in inhibited TNF-alpha production in activated Daudi cells. Human immunology 4 18486760
2023 Proteomics-Based Discovery of First-in-Class Chemical Probes for Programmed Cell Death Protein 2 (PDCD2). Angewandte Chemie (International ed. in English) 3 37658265
2022 Identification of PDCD2 as a Candidate Target of Andrographolide That Arrests the Tumor Cell Cycle by Human Proteome-Scale Screening. ACS pharmacology & translational science 3 35837135
2025 Biallelic variants in the conserved ribosomal protein chaperone gene PDCD2 are associated with hydrops fetalis and early pregnancy loss. Proceedings of the National Academy of Sciences of the United States of America 1 40208938
2026 Biosensor-guided discovery of peptide inhibitors targeting the ribosomal protein uS5-PDCD2 chaperone interaction. The Journal of biological chemistry 0 41933732