Affinage

PDCD2

uS5 assembly chaperone PDCD2 · UniProt Q16342

Length
344 aa
Mass
38.6 kDa
Annotated
2026-06-10
24 papers in source corpus 18 papers cited in narrative 17 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

PDCD2 is an evolutionarily conserved MYND-domain protein that functions as a dedicated co-translational chaperone for the 40S ribosomal protein uS5 (RPS2), a role essential for small ribosomal subunit biogenesis and embryonic viability (PMID:33245768, PMID:40208938). PDCD2 recognizes nascent uS5 in the cytoplasm through the N-terminal 30 residues of uS5, with a conserved FxxGFG hydrophobic motif mediating the interaction, and escorts uS5 from co-translational recognition to nuclear ribosome assembly sites (PMID:33245768, PMID:41933732). Loss of PDCD2 reduces soluble uS5, impairs its incorporation into the 40S subunit, and disrupts rRNA processing, phenocopying uS5 deficiency (PMID:33245768, PMID:40208938). Consistent with a ribosome biogenesis function, PDCD2 deficiency triggers p53-dependent G1-to-S cell cycle arrest in mouse fibroblasts, ESCs, and blastocysts, and PDCD2 is required for inner cell mass development and embryonic stem cell maintenance (PMID:20813103, PMID:25150276). The conserved chaperone activity underlies tissue-level roles in hematopoiesis and stem cell function: the Drosophila ortholog Zfrp8 is required in hematopoietic and germline/follicle stem cells, where it forms a complex with the piRNA pathway protein Maelstrom and controls transposable element activity (PMID:17522156, PMID:24381196), and PDCD2 is required for hematopoietic stem cell emergence and erythroid differentiation in vertebrate models (PMID:22800338, PMID:22922207). Biallelic loss-of-function PDCD2 variants that reduce protein levels and impair uS5 binding cause a human disorder with altered rRNA processing (PMID:40208938). Additional reported activities include MYND-domain-mediated association with the HCF-1/N-CoR/SIN3A corepressor axis and transcriptional repression of PDCD2 by BCL6 (PMID:11854457, PMID:17468402, PMID:12149646).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 2002 High

    Established the first regulatory and physical context for PDCD2 by showing its expression is controlled by an oncogenic transcription factor and its MYND domain engages a transcriptional corepressor machinery.

    Evidence Promoter binding, siRNA knockdown, and immunohistochemistry for BCL6 repression; reciprocal pulldown and complementation for the HCF-1/N-CoR/mSin3A interaction

    PMID:11854457 PMID:12149646 PMID:17468402

    Open questions at the time
    • Does not define a direct biochemical activity for PDCD2 itself
    • Functional consequence of the corepressor association for endogenous gene regulation is unresolved
  2. 2007 High

    Placed the PDCD2 ortholog in a conserved stem cell proliferation/cell-cycle pathway, linking it genetically to centrosome and APC components.

    Evidence Drosophila Zfrp8 loss-of-function, genetic epistasis with Dgrip91 and Cdc27, and subcellular localization in lymph gland

    PMID:17522156

    Open questions at the time
    • Molecular activity behind the cell-cycle phenotype not defined
    • Direct physical targets not identified
  3. 2010 High

    Defined PDCD2 as essential for early mammalian development and ESC maintenance, fixing the loss-of-function phenotype at the organismal level.

    Evidence Targeted knockout mice, blastocyst outgrowth assays, and ESC derivation attempts with rescue transgene

    PMID:20605493 PMID:20813103

    Open questions at the time
    • Mechanism connecting PDCD2 loss to developmental failure not established at this stage
    • Pro-apoptotic activity seen only on overexpression, of uncertain physiological relevance
  4. 2012 Medium

    Demonstrated a conserved requirement for PDCD2 in hematopoietic stem cell emergence and erythroid lineage commitment across vertebrate systems.

    Evidence Zebrafish morpholino knockdown with runx1/Jak-Stat epistasis; shRNA knockdown in human CD34+ progenitors and K562 cells with lineage marker and cell cycle readouts

    PMID:22800338 PMID:22922207

    Open questions at the time
    • Whether hematopoietic effects are downstream of a ribosome biogenesis role was not yet known
    • Morpholino-based zebrafish results require orthogonal genetic confirmation
  5. 2014 High

    Connected PDCD2 to the p53 axis and to the piRNA/transposon-silencing machinery, and identified a key physical partner in the germline.

    Evidence Conditional MYND-domain knockout in MEFs/ESCs/blastocysts with p53 induction; Drosophila Zfrp8-Maelstrom Co-IP, localization, TE activity assays, and human PDCD2 cross-species rescue

    PMID:24381196 PMID:25150276

    Open questions at the time
    • Mechanism linking PDCD2 loss to p53 stabilization not yet defined
    • Direct molecular substrate of PDCD2 still unknown at this point
  6. 2016 Medium

    Identified the 40S ribosomal protein uS5/RpS2 as a direct PDCD2 interactor and localized PDCD2's function to late-stage ribosome assembly.

    Evidence Co-IP of Zfrp8/PDCD2 with RpS2 and imaging of ribosomal protein distribution and mRNA export in knockdown ovaries

    PMID:26807849

    Open questions at the time
    • Did not establish the co-translational nature of the interaction
    • Binding interface and mechanism of escort not defined
  7. 2020 High

    Established the core mechanistic model: PDCD2 is a dedicated co-translational chaperone that recognizes nascent uS5 and delivers it to nuclear assembly sites for 40S biogenesis.

    Evidence Quantitative interactome proteomics, co-translational assembly assay, sucrose gradient sedimentation, and subcellular fractionation in human cells

    PMID:33245768

    Open questions at the time
    • Atomic-resolution structure of the PDCD2-uS5 complex not determined
    • Handoff mechanism to downstream assembly factors not resolved
  8. 2025 High

    Linked PDCD2 to a human Mendelian disorder and confirmed the chaperone function is the disease-relevant activity in vivo.

    Evidence Exome sequencing with patient fibroblast functional validation, Co-IP of PDCD2-uS5 binding, rRNA processing assays, and Xenopus knockdown phenotyping

    PMID:40208938

    Open questions at the time
    • Full clinical spectrum and genotype-phenotype correlation not defined here
    • Tissue-specific vulnerability to PDCD2 loss not explained
  9. 2026 High

    Mapped the molecular determinants of the PDCD2-uS5 interaction to a defined uS5 N-terminal FxxGFG motif and validated it as a druggable interface.

    Evidence Affinity purification with domain mapping, structural modeling, NanoLuc split biosensor, and a uS5-derived peptide inhibitor in cancer cells

    PMID:41933732

    Open questions at the time
    • Experimental high-resolution structure of the interface not solved
    • Selectivity and therapeutic window of interface disruption not established

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the ribosome-biogenesis chaperone function mechanistically integrates with PDCD2's reported transcriptional/corepressor and apoptotic activities, and which are physiologically primary, remains unresolved.
  • No unifying model reconciles the MYND-domain corepressor role with the cytoplasmic/nuclear chaperone role
  • Whether RNA-binding/mRNA-export effects are direct or secondary to ribosome defects is unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0044183 protein folding chaperone 3 GO:0140110 transcription regulator activity 2
Localization
GO:0005634 nucleus 2 GO:0005829 cytosol 1
Pathway
R-HSA-1266738 Developmental Biology 3 R-HSA-1640170 Cell Cycle 2 R-HSA-8953854 Metabolism of RNA 2
Partners
HCFC1MAELSTROMNCOR1RPS2

Evidence

Reading pass · 17 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2002 BCL6 represses PDCD2 transcription by binding directly to the PDCD2 promoter; knockdown of endogenous BCL6 in a human B cell lymphoma line increases PDCD2 protein expression. VP16-BCL6 competition assay, subtractive hybridization, siRNA knockdown, immunohistochemistry Proceedings of the National Academy of Sciences of the United States of America High 11854457 17468402
2002 The MYND domain of PDCD2 interacts with the C-terminal WYF domain of HCF-1 (HCFC1); this interaction is conserved with 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, while overexpression of interaction-disrupting domains of either protein enhances complementation. Co-immunoprecipitation/pulldown, complementation assay with temperature-sensitive HCF-1 mutant, domain overexpression Oncogene Medium 12149646
2007 Drosophila Zfrp8 (PDCD2 ortholog) is required for normal hematopoietic stem cell proliferation and differentiation; loss-of-function causes lymph gland hyperplasia with increased undifferentiated hemocyte proliferation, altered subcellular distribution of gamma-Tubulin and Cyclin B, and genetic interactions with Dgrip91 (centrosome-associated) and Cdc27 (APC component), placing Zfrp8 in a centrosome/cell-cycle regulation pathway. Genetic loss-of-function (mutant analysis), genetic epistasis, subcellular localization (immunofluorescence), enhancement assays with Dgrip91 and Cdc27 mutants Development (Cambridge, England) High 17522156
2010 PDCD2 is required for inner cell mass development and embryonic stem cell maintenance; Pdcd2-/- mouse embryos fail to develop past implantation, ICMs from null blastocysts fail to outgrow in vitro, and PDCD2-null ESCs cannot be established without an ectopic transgene. PDCD2 levels decline upon ESC differentiation. Targeted gene disruption in mice (knockout), in vitro blastocyst outgrowth assay, ESC derivation attempts with rescue transgene Developmental biology High 20813103
2010 Overexpression of PDCD2 induces apoptosis in human cell lines through activation of the caspase cascade; caspase inhibitors block this effect. VP16-BCL6 competition (which increases PDCD2 expression) increases apoptosis, and PDCD2-specific siRNA knockdown inhibits apoptosis. Transfection/overexpression, caspase inhibitor assays, siRNA knockdown, flow cytometry for apoptosis Blood cells, molecules & diseases Medium 20605493
2014 Zfrp8/PDCD2 is required in both germline and follicle stem cells in the Drosophila ovary. Nuclear localization of Zfrp8 in germline stem cells is regulated by piRNA pathway genes. Zfrp8 forms a complex with the piRNA pathway protein Maelstrom and controls Maelstrom accumulation in the nuage. Zfrp8 regulates the activity of specific transposable elements also controlled by Maelstrom and Piwi. Human PDCD2 fully rescues the Zfrp8 phenotype. Genetic loss-of-function, co-immunoprecipitation (Zfrp8-Maelstrom complex), live/fixed imaging of nuclear localization, transposable element activity assays, cross-species rescue Development (Cambridge, England) High 24381196
2014 Conditional knockout of PDCD2 (deleting exon 2 containing the MYND domain) in mouse embryonic fibroblasts and ESCs causes G1-to-S phase cell cycle arrest associated with increased p53 protein levels and p53 target gene expression. Similar nuclear p53 induction and S-phase entry failure were observed in PDCD2 knockout blastocysts. Tamoxifen-inducible conditional knockout (Cre-lox), cell cycle analysis, p53 immunostaining, qRT-PCR for p53 targets Biology open High 25150276
2016 Zfrp8/PDCD2 directly interacts with the small (40S) ribosomal subunit protein RpS2 (uS5). Zfrp8/PDCD2 knockdown leads to increased nuclear accumulation of specific mRNAs and TE transcripts, and reduces cytoplasmic levels of 40S ribosomal subunit components without affecting nuclear/nucleolar localization of ribosomal proteins, suggesting a role at late stages of ribosome assembly. Co-immunoprecipitation, fluorescence imaging of ribosomal protein distribution in KD ovaries, RNA analysis PloS one Medium 26807849
2020 Human PDCD2 functions as a dedicated ribosomal protein chaperone specifically for the 40S ribosomal protein uS5 (RPS2). The PDCD2-uS5 complex assembles co-translationally. Loss of PDCD2 reduces soluble uS5 protein levels and its incorporation into the 40S subunit, causing defects in small ribosomal subunit synthesis that phenocopy uS5 deficiency. PDCD2 accompanies uS5 from cytoplasmic co-translational recognition to ribosome assembly sites in the nucleus. Quantitative proteomics (PDCD2 interactome), co-translational complex assembly assay, ribosome profiling/sucrose gradient sedimentation, loss-of-function with RNAi/siRNA, subcellular fractionation Nucleic acids research High 33245768
2012 Pdcd2 knockdown in zebrafish embryos causes defects in hematopoietic stem cell emergence and differentiation; HSCs fail to appear in the aorta-gonad-mesonephros region and cannot terminally differentiate. The effects are cell-autonomous and p53-independent. Restoration of runx1 function or inhibition of Jak/Stat signaling rescues hematopoietic defects, placing pdcd2 upstream of runx1 in the hematopoietic transcriptional hierarchy. Morpholino knockdown in zebrafish, genetic epistasis (runx1 rescue, Jak/Stat inhibition), cell autonomy assays Stem cells and development Medium 22800338
2012 PDCD2 knockdown in human CD34+ hematopoietic progenitors and K562 cells specifically impairs erythroid differentiation (reducing erythroid-specific factors GATA-1, EpoR, and γ-globin, and increasing early progenitor factors c-MYB and GATA-2) while megakaryocytic differentiation is unaffected. PDCD2 loss induces G0/G1 cell cycle arrest. shRNA knockdown, colony-forming assays, flow cytometry, qRT-PCR for lineage markers Experimental hematology Medium 22922207
2015 PDCD2 and NCoR1 interact (co-immunoprecipitation), and their exogenous co-expression in GIST cell lines decreases proliferation, increases apoptosis, and causes G1 cell cycle arrest. PDCD2 and NCoR1 activate Smad2 and Smad3, linking them to the TGF-β/Smad signaling pathway. Co-immunoprecipitation, overexpression, CCK-8 proliferation assay, flow cytometry (PI/Annexin V), Western blotting for Smad2/3 Cellular oncology (Dordrecht, Netherlands) Medium 26589942
2019 PDCD2 inhibits epithelial-mesenchymal transition (EMT) in sorafenib-resistant HepG2 cells by suppressing Vimentin and increasing E-cadherin expression in a Snail-dependent manner, thereby promoting sorafenib-induced apoptosis and reducing cell migration. RT-qPCR, Western blotting, Annexin V/FITC apoptosis assay, cell migration assay Molecular medicine reports Low 30664177
2022 PDCD2 binds andrographolide (identified by proteome chip screening); PDCD2 bound to andrographolide blocks the nuclear export of CDK mRNAs, reduces CDK protein levels, and causes cell cycle arrest. RNA-binding protein immunoprecipitation confirmed PDCD2 associates with cell cycle-related mRNAs. Proteome chip drug-target screen, RNA-binding protein immunoprecipitation, nuclear/cytoplasmic mRNA distribution analysis, in vivo tumor growth assay ACS pharmacology & translational science Low 35837135
2023 A first-in-class small molecule degrader (10e) of PDCD2 was identified by chemical proteomics; pharmacological degradation of PDCD2 impairs T lymphoblast cell cycle progression, demonstrating that PDCD2 is a critical regulator of cell growth. Chemical proteomics, PDCD2 degrader (PROTAC-like), cell cycle analysis by flow cytometry Angewandte Chemie (International ed. in English) Medium 37658265
2025 Biallelic loss-of-function variants in PDCD2 reduce PDCD2 protein levels, impair PDCD2 binding to uS5, and alter ribosomal RNA processing in patient fibroblasts and engineered cell lines. Pdcd2 knockdown in Xenopus tadpoles causes developmental defects and edema with altered rRNA processing, establishing that PDCD2-uS5 chaperone function is essential for ribosome biogenesis and embryonic viability. Exome sequencing + functional validation in patient fibroblasts, Co-IP (PDCD2-uS5 binding), rRNA processing assays, Xenopus morpholino knockdown with in vivo phenotyping Proceedings of the National Academy of Sciences of the United States of America High 40208938
2026 The N-terminal 30 amino acids of uS5 are necessary and sufficient for interaction with PDCD2, and a conserved FxxGFG motif in this region mediates hydrophobic interaction with PDCD2. An 11-amino acid uS5-derived peptide inhibits the PDCD2-uS5 interaction in a cell-based biosensor and impairs cancer cell viability. Affinity purification, structural modeling, complementation-based biosensor (NanoLuc split), peptide inhibitor assay, cell viability assay The Journal of biological chemistry High 41933732

Source papers

Stage 0 corpus · 24 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
2010 PDCD2 is essential for inner cell mass development and embryonic stem cell maintenance. Developmental biology 30 20813103
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
2020 PDCD2 functions as an evolutionarily conserved chaperone dedicated for the 40S ribosomal protein uS5 (RPS2). Nucleic acids research 22 33245768
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
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
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 9 22922207
2005 Cloning of cDNAs with PDCD2(C) domain and their expressions during apoptosis of HEK293T cells. Molecular and cellular biochemistry 8 16311922
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 2 40208938
2026 Biosensor-guided discovery of peptide inhibitors targeting the ribosomal protein uS5-PDCD2 chaperone interaction. The Journal of biological chemistry 0 41933732

Missed literature

Know a paper Affinage missed for PDCD2? Flag it for the maintainers and the community.

No submissions yet.