ANAPC7

ANAPC7 (APC7) is a tetratricopeptide repeat (TPR)-containing core subunit of the anaphase-promoting complex/cyclosome (APC/C) E3 ubiquitin ligase that functions in cell-cycle progression and post-mitotic ubiquitin-dependent proteolysis. CDK1-dependent phosphorylation of APC7 and other APC/C TPR subunits during mitosis promotes CDC20 binding and APC/C activation (PMID:14657031). In post-mitotic neurons, APC7 is specifically required for CDH1-APC/C-mediated ubiquitination of Ki-67, and loss-of-function mutations in ANAPC7 cause an intellectual disability syndrome characterized by neuronal heterochromatin dysregulation (PMID:34942119). APC7 also modulates mitotic checkpoint sensitivity, acting as a genetic modifier in epistasis with KIF18A during mitotic progression (PMID:40596695).

1. 2003 High

   Identifying mitosis-specific phosphorylation of APC/C subunits including APC7 by CDK1, and showing this phosphorylation is sufficient for CDC20 binding, established the regulatory mechanism by which the APC/C is activated at mitotic entry.

   Evidence Mass spectrometry phospho-site mapping combined with in vitro CDK1/PLK1 kinase assays and CDC20 binding assays on purified APC/C

   PMID:14657031

   Open questions at the time

   • Individual contributions of APC7 phospho-sites versus other TPR subunit sites to CDC20 recruitment were not dissected
   • No in vivo mutagenesis of APC7 phospho-sites to confirm functional necessity
2. 2005 Low

   Correlating loss of APC7 protein in breast carcinomas with high mitotic index and aneuploidy raised the possibility that APC7 downregulation contributes to tumorigenesis, though direct causality was not tested.

   Evidence Immunohistochemistry on 108 invasive ductal breast carcinomas with clinicopathologic correlation

   PMID:15743504

   Open questions at the time

   • Correlation only; no functional rescue or knockdown experiments to establish causality
   • APC7 loss could be a passenger event rather than a driver
   • No mechanistic link between APC7 loss and the observed aneuploidy was demonstrated
3. 2010 Medium

   Systematic proteomic identification of APC7 as a conserved APC/C subunit through tandem-affinity purification confirmed its stable integration into the complex and provided localization data.

   Evidence BAC-based gene tagging with tandem-affinity purification–mass spectrometry in the MitoCheck consortium

   PMID:20360068

   Open questions at the time

   • Study was systematic rather than APC7-focused; no functional dissection of APC7 within the complex
   • Stoichiometry and structural position within the APC/C not resolved here
4. 2021 High

   Demonstrating that APC7 is specifically required for CDH1-APC/C-dependent ubiquitination of Ki-67 in neurons, and that patient loss-of-function mutations cause intellectual disability with heterochromatin dysregulation, established a post-mitotic, tissue-specific role for this APC/C subunit and linked it to human disease.

   Evidence Patient genetics, conditional Apc7/Cdh1/Cdc20 knockout mouse models, quantitative brain proteomics, and immunofluorescence

   PMID:34942119

   Open questions at the time

   • How APC7 selectively promotes CDH1-dependent but not CDC20-dependent substrate recognition is structurally unexplained
   • Whether Ki-67 accumulation is the primary driver of the intellectual disability phenotype or a marker of broader heterochromatin defects is unresolved
   • Whether other tissues are similarly affected by APC7 loss-of-function has not been systematically examined
5. 2024 Medium

   Identifying APC7 as a genetic modifier that opposes KIF18A-dependent mitotic checkpoint signaling revealed a new axis of APC/C regulation of mitotic fidelity distinct from canonical substrate degradation.

   Evidence siRNA co-depletion in cell lines with mitotic arrest readout, supported by genetic association with retroviral insertion in mouse strain backgrounds

   PMID:39677807 PMID:40596695

   Open questions at the time

   • Mechanism by which APC7 modulates checkpoint sensitivity (direct substrate versus indirect regulation) is unknown
   • Opposing effects of APC7 versus ANAPC5 co-depletion on mitotic arrest remain unexplained at a biochemical level
   • Retroviral insertion effect on Anapc7 expression or splicing has not been functionally validated

• Key unresolved questions include the structural basis for APC7's selective requirement in CDH1-APC/C activity, the identity of additional APC7-dependent substrates beyond Ki-67, and the molecular mechanism by which APC7 modulates mitotic checkpoint sensitivity in epistasis with KIF18A.
• No high-resolution structure of APC7 in the context of the CDH1-bound APC/C is available
• Full substrate repertoire of APC7-dependent ubiquitination in different tissues is uncharacterized
• Direct biochemical link between APC7 and mitotic checkpoint components has not been demonstrated