TSPYL5

TSPYL5 is a nucleosome assembly protein (NAP)-family member that acts predominantly as a negative regulator of p53, governing proliferation, senescence, and stemness in normal and cancer cells (PMID:21170034, PMID:30471052). Its founding biochemical activity is direct binding to the deubiquitylase USP7, which it inhibits to drive p53 ubiquitylation and degradation, thereby overriding p53-dependent proliferation arrest and oncogene-induced senescence (PMID:21170034). TSPYL5 deploys this anti-p53 logic in multiple contexts: in endothelial cells it lowers p53 to promote proliferation, migration, and angiogenesis (PMID:30471052); in spermatogonia it facilitates ubiquitination-mediated TRP53 degradation to upregulate PCNA-driven DNA replication (PMID:38185096); and in neuroblastoma it binds G3BP1 and enhances its Ser149 phosphorylation, nucleating a RanBP2–G3BP1–p53 complex that accelerates p53 sumoylation and nuclear export to sequester p53 in the cytoplasm (PMID:40319028). Beyond p53, TSPYL5 sustains PI3K/AKT signaling by suppressing PTEN — directly downregulating PTEN to lower AKT activity when depleted (PMID:20079711), and in triple-negative breast cancer sequestering the deubiquitinase USP10 to trigger PTEN proteasomal degradation and a ZEB1-driven EMT program (PMID:42241080). AKT in turn phosphorylates TSPYL5 at Thr120, stabilizing it and driving its nuclear translocation where it transcriptionally activates the stem-cell genes ALDH1 and CD44 while repressing PTEN, forming a self-reinforcing AKT/TSPYL5/PTEN feedback loop (PMID:34163000). TSPYL5 also functions as a sequence-specific transcriptional activator, binding the CYP19A1 (aromatase) promoter I.4 to upregulate aromatase expression (PMID:23518928). In ALT+ cancer cells it localizes to telomeric PML bodies and protects the shelterin component POT1 from USP7- and PML-dependent ubiquitination and degradation (PMID:31278054). TSPYL5 is an intrinsically disordered protein whose N-terminal disordered region (residues 4–27) carries NLS/NoLS signals directing nuclear/nucleolar localization, while its ordered NAP-like domain directs cytoplasmic localization (PMID:38203210).

1. 2010 High

   Established the founding molecular mechanism: how TSPYL5 controls cell fate by linking it to the p53 ubiquitylation machinery rather than acting through an unknown route.

   Evidence Mass spectrometry of TSPYL5 interactors, co-IP, ubiquitylation assays, and proliferation/senescence assays identifying USP7 inhibition and p53 destabilization

   PMID:21170034

   Open questions at the time

   • Does not define the structural basis of USP7 inhibition
   • Does not establish whether TSPYL5 acts catalytically or stoichiometrically on USP7
2. 2010 Medium

   Connected TSPYL5 to a second tumor-suppressor axis by showing it regulates the PTEN/AKT pathway and the radiation response, broadening its role beyond p53.

   Evidence siRNA knockdown and overexpression in lung cancer lines with PTEN/AKT/p21 Western blots, colony formation, and gamma-irradiation survival assays

   PMID:20079711

   Open questions at the time

   • Mechanism by which TSPYL5 regulates PTEN not defined at this stage
   • Single lab, two cell lines
3. 2013 Medium

   Demonstrated TSPYL5 has direct sequence-specific transcriptional activity, establishing it as a DNA-binding transactivator rather than solely a protein-interaction scaffold.

   Evidence ChIP showing binding to CYP19A1 promoter I.4, knockdown/overexpression across multiple cell types, and reporter assays

   PMID:23518928

   Open questions at the time

   • No structural definition of the DNA-binding interface
   • The broader 43-gene putative target set remains uncharacterized functionally
4. 2017 Medium

   Placed TSPYL5 downstream of an upstream signaling cascade, identifying how its expression is controlled in cancer.

   Evidence MUC16 shRNA knockdown, transcriptome analysis, MUC16-Cter rescue, and STAT3 inhibition in lung cancer cells

   PMID:28196872

   Open questions at the time

   • Direct vs indirect transcriptional control of TSPYL5 not resolved
   • Single lab
5. 2018 Medium

   Extended the anti-p53 function to a physiological vascular context, showing TSPYL5 promotes angiogenesis by suppressing p53.

   Evidence Overexpression/knockdown in HUVECs and hPSC-ECs with p53-inhibitor rescue, Matrigel plug, and mouse wound-healing models

   PMID:30471052

   Open questions at the time

   • Does not establish whether the USP7 mechanism operates in endothelial cells
   • Single lab
6. 2019 High

   Revealed a p53-independent role at telomeres, showing TSPYL5 protects POT1 from degradation specifically in ALT+ cancer cells.

   Evidence TSPYL5 depletion, PML-body co-localization, ubiquitination and proteasome-inhibitor assays, and USP7/PML knockdown epistasis

   PMID:31278054

   Open questions at the time

   • Identity of the POT1 E3 ligase activated by USP7 not established
   • Why protection is ALT-specific not mechanistically resolved
7. 2021 High

   Identified the post-translational switch governing TSPYL5 nuclear function, defining a feedback loop that sustains cancer stemness.

   Evidence T120 phosphosite mutagenesis, ubiquitination assays, nuclear fractionation, transcriptional reporters and ChIP in NSCLC cells

   PMID:34163000

   Open questions at the time

   • Direct vs indirect PTEN promoter repression not fully separated from ALDH1/CD44 activation
   • Identity of the E3 ligase counteracted by T120 phosphorylation unknown
8. 2023 Medium

   Mapped the determinants of TSPYL5 subcellular partitioning, linking its disordered N-terminus to nuclear/nucleolar targeting and its NAP domain to cytoplasmic retention.

   Evidence Live-cell imaging of EGFP fusions, FRAP, and deletion/truncation constructs

   PMID:38203210

   Open questions at the time

   • Phase separation only inferred, not reconstituted
   • Functional consequence of nucleolar pool not defined
9. 2024 Medium

   Provided in vivo genetic evidence for a physiological role, showing Tspyl5 drives spermatogonia proliferation via p53 degradation and PCNA upregulation.

   Evidence Tspyl5 knockout mice, spermatogonia transcriptomics, TRP53 ubiquitination assays, and PCNA Westerns

   PMID:38185096

   Open questions at the time

   • Does not confirm the USP7 mechanism operates in spermatogonia
   • Single lab, mouse model
10. 2025 Medium

    Defined a new p53-suppressing mechanism via spatial regulation, showing TSPYL5 drives p53 nuclear export and sumoylation through a G3BP1-RanBP2 axis.

    Evidence Co-IP, phosphorylation and sumoylation assays, nuclear fractionation, and complex reconstitution in neuroblastoma cells

    PMID:40319028

    Open questions at the time

    • Direct kinase mediating G3BP1 Ser149 phosphorylation not identified
    • Single lab, single study
11. 2026 Medium

    Identified USP10 as a new TSPYL5 partner explaining PTEN destabilization in TNBC even with wild-type PTEN, linking TSPYL5 to EMT and metastasis.

    Evidence Co-IP of TSPYL5-USP10, ubiquitination/stability assays, orthotopic metastasis models, and single-cell/spatial transcriptomics

    PMID:42241080

    Open questions at the time

    • Reciprocal validation of the sequestration mechanism limited
    • Single lab, single study

• It remains unresolved how TSPYL5's distinct activities — USP7/USP10 deubiquitylase modulation, sequence-specific transcription, telomeric POT1 protection, and p53 spatial control — are coordinated as a single biochemical mechanism versus context-dependent moonlighting functions.
• No structure of TSPYL5 or its complexes
• No unifying biochemical model linking its deubiquitylase-regulatory and transcriptional activities
• Whether NAP-family nucleosome assembly activity is biochemically active is untested in the corpus