KCTD10

KCTD10 is the substrate-recognition subunit of a CUL3-RING (CRL3) E3 ubiquitin ligase that selects diverse protein substrates for ubiquitination, thereby controlling endothelial barrier function, cancer cell behavior, brain development, and genome stability (PMID:29358211, PMID:41062692). Through its BTB domain it bridges CUL3 to substrates and directs distinct ubiquitin linkages to different fates: K63-linked polyubiquitination of RhoB at K162/K181 routes RhoB to lysosomes to govern endothelial contraction and barrier integrity, and the same axis relieves RhoB-mediated suppression of Rac1 to enable membrane ruffling and proliferation (PMID:29358211, PMID:30515933); K27-linked ubiquitination of EIF3D and K48-linked degradation of β-catenin (via BTB engagement of the Armadillo repeats), the latter lowering PD-L1, are additional substrate routes (PMID:31280863, PMID:40873559). KCTD10 further destabilizes SLC7A11 to limit cystine uptake and promote ferroptosis, with USP18 acting as the counteracting deubiquitylase (PMID:38959043), and degrades IGF2BP1 to curb m6A-dependent IL-11 mRNA stabilization and immune evasion (PMID:42107984). In development it degrades KCTD13 to control cortical neuronal progenitor proliferation (PMID:38489388) and degrades Notch1 in concert with Cullin3, with KCTD10 loss causing embryonic lethality with angiogenesis and heart defects and Notch upregulation (PMID:25401743), while it also acts upstream of Notch in brown adipose thermogenesis (PMID:34854382) and directly binds and represses the transcription factor Tbx5a during cardiac development (PMID:24430697). At co-directional transcription-replication conflicts KCTD10 acts as a bivalent sensor, simultaneously engaging the replisome and transcription machinery and forming higher-order assemblies that recruit CUL3 to ubiquitinate and remove the elongation factor TCEA2, permitting replisome bypass (PMID:41062692). KCTD10 partitions into condensates through liquid-liquid phase separation driven by its intrinsically disordered region; the schizophrenia-associated p.C124W mutation disrupts this phase separation and impairs RhoB degradation, causing synaptic abnormalities and schizophrenia-like behavior in mice (PMID:39565307).

1. 2005 Medium

   Established the first molecular associations of KCTD10, placing it with the DNA replication/repair machinery before any enzymatic role was known.

   Evidence Cloning and protein interaction assays linking rat KCTD10 to DNA polymerase delta small subunit and PCNA

   PMID:15982757

   Open questions at the time

   • No catalytic activity assigned
   • Interaction with replication machinery not mechanistically connected to a ubiquitination function at this stage
2. 2009 Medium

   Confirmed the PCNA interaction and tied KCTD10 to cell proliferation, with nuclear localization, reinforcing a replication-associated role.

   Evidence Yeast two-hybrid, reciprocal Co-IP, siRNA knockdown proliferation assay and immunofluorescence in A549 cells

   PMID:19125419

   Open questions at the time

   • Mechanism linking PCNA binding to proliferation unresolved
   • No E3 ligase activity demonstrated
3. 2009 High

   Defined transcriptional control of KCTD10 itself, showing opposing SP1 activation and AP-2alpha repression at its promoter.

   Evidence Deletion/site-directed mutagenesis, ChIP, luciferase reporter assays, qRT-PCR and western blot

   PMID:19154347

   Open questions at the time

   • Upstream signals controlling SP1/AP-2alpha balance not defined
   • Does not address KCTD10 protein function
4. 2012 Medium

   Identified KCTD10 as a regulator of NF-kappaB/AP-1 transcriptional activity and a target of TNFAIP1-promoted proteasomal degradation, introducing reciprocal regulation within the KCTD/TNFAIP1 family.

   Evidence Yeast two-hybrid, GST pull-down, Co-IP, MG132 ubiquitination assay, luciferase reporter assays

   PMID:22810651

   Open questions at the time

   • E3 ligase responsible for KCTD10 turnover not defined
   • Direct vs indirect effect on NF-kappaB/AP-1 unresolved
5. 2014 High

   Revealed KCTD10's developmental requirement, showing it directly binds and represses Tbx5a to pattern the atrioventricular canal in vivo.

   Evidence Zebrafish mutant screen, morpholino epistasis with tbx5a and has2, direct Kctd10-Tbx5 binding assay, cardiac marker in situ hybridization

   PMID:24430697

   Open questions at the time

   • Whether repression is ubiquitination-dependent not addressed
   • Relationship to CUL3 complex unclear in this context
6. 2014 Medium

   Connected KCTD10 to the CUL3 E3 machinery and Notch signaling, establishing that it mediates Notch1 degradation and is essential for embryonic angiogenesis and cardiac development.

   Evidence KCTD10 knockout mice (~E10.5 lethality), endogenous Co-IP with Cullin3 and Notch1, qRT-PCR, VEGF stimulation in HUVECs; parallel zebrafish knockdown linking heart defects to RhoA/PCNA

   PMID:24705121 PMID:25401743

   Open questions at the time

   • Direct ubiquitination of Notch1 not biochemically resolved
   • Ubiquitin linkage type unspecified
7. 2018 High

   Defined the first rigorous substrate-and-linkage mechanism: the CUL3-Rbx1-KCTD10 ligase catalyzes K63 polyubiquitination of RhoB to route it to lysosomes and control endothelial barrier integrity.

   Evidence Co-IP, K63-specific ubiquitination assays, RhoB lysine mutagenesis (K162/K181), lysosomal inhibition, endothelial barrier (TEER/permeability) assays

   PMID:29358211

   Open questions at the time

   • How KCTD10 selects RhoB over other Rho GTPases not defined
   • In vivo barrier relevance not yet tested at this stage
8. 2019 Medium

   Extended the RhoB axis to cancer signaling and identified a second substrate, showing CUL3/KCTD10-driven RhoB degradation enables Rac1 activation and proliferation, and that the complex K27-ubiquitinates EIF3D.

   Evidence siRNA depletion, Rac1 activity and proliferation assays, membrane ruffle quantification (RhoB/Rac1); MS, K27-specific ubiquitination assay and EIF3D lysine mutagenesis (K153/K275)

   PMID:30515933 PMID:31280863

   Open questions at the time

   • Functional consequence of EIF3D K27 ubiquitination not established
   • Substrate determinants distinguishing linkage choice unknown
9. 2022 Medium

   Placed KCTD10 genetically upstream of Notch in metabolic tissue, where it restrains brown-fat thermogenesis.

   Evidence BAT-specific knockdown and overexpression mice, UCP1 western blot, Notch inhibitor rescue, metabolic phenotyping

   PMID:34854382

   Open questions at the time

   • Whether the Notch effect is via direct KCTD10-mediated ubiquitination in BAT not shown
   • Substrate in this context not identified
10. 2024 High

    Expanded the substrate repertoire and physiological reach: KCTD10 destabilizes SLC7A11 to promote ferroptosis (opposed by USP18), degrades KCTD13 to control cortical development, and undergoes IDR-driven phase separation required for RhoB degradation at synapses, disrupted by a schizophrenia mutation.

    Evidence MLN4924, ubiquitination/cystine-uptake/ferroptosis assays and tumor growth (SLC7A11); brain-specific KO, Co-IP and ubiquitination, cortical markers and behavior (KCTD13); C124W knockin mice, LLPS and IDR-deletion assays, PSD fractionation (RhoB)

    PMID:38489388 PMID:38959043 PMID:39565307

    Open questions at the time

    • How phase separation is coupled to E3 catalytic output mechanistically unresolved
    • Structural basis of distinct substrate recognition across contexts not defined
11. 2025 High

    Revealed a genome-stability role and further substrates: KCTD10 senses co-directional transcription-replication conflicts and removes TCEA2 to allow replisome bypass, degrades β-catenin via its BTB domain (lowering PD-L1), and degrades IGF2BP1 to limit m6A-driven IL-11 immune evasion.

    Evidence Co-IP with replisome and transcription machinery, TCEA2 ubiquitination and TRC/DNA-damage assays in KO cells (Nature); IP-MS, K48 ubiquitination, domain mapping and endothelial-specific KO mice (β-catenin); ubiquitination, half-life, RNA pull-down and allograft (IGF2BP1)

    PMID:40873559 PMID:41062692 PMID:42107984

    Open questions at the time

    • How KCTD10 discriminates co-directional from head-on conflicts mechanistically unclear
    • Whether higher-order assembly applies to non-TRC substrates unknown

• It remains unresolved how a single substrate adaptor selects such diverse substrates and dictates different ubiquitin linkage types (K27, K48, K63) and outcomes across tissues, and how phase separation, conflict sensing, and CUL3 catalysis are integrated.
• No structural model of KCTD10 substrate recognition across its many targets
• Rules governing K27/K48/K63 linkage selection unknown
• Relationship between early PCNA/replication interactions and the later TRC-sensing role not biochemically reconciled