CEP85

CEP85 is a centrosomal scaffold protein that governs both centriole biogenesis and centrosome separation through direct, mutually exclusive kinase-coupled interactions (PMID:26220856, PMID:29712910). In centriole assembly, CEP85 directly binds STIL through a conserved interface, and this interaction is essential for centriolar targeting of STIL, PLK4 activation, and faithful daughter centriole formation (PMID:29712910). In centrosome integrity control, CEP85 localizes to the proximal ends of centrioles, directly binds Nek2A, and inhibits its kinase activity, cooperating with PP1γ to antagonize Nek2A and suppress precocious centrosome separation during interphase (PMID:26220856). At G2/M this restraint is relieved: CEP85 forms a PLK1–CEP85–Nek2A ternary complex in which PLK1 phosphorylates CEP85 in a Nek2A-binding-dependent manner, driving CEP85 to dissociate from phospho-Nek2A and freeing active Nek2A to initiate centrosome disjunction (PMID:30611117). Beyond the centrosome, the CEP85–STIL complex is recruited by PLK4 to the leading edge of migrating cells, where it sustains ARP2 (ACTR2) phosphorylation and actin-dependent directional motility (PMID:32107292).

1. 2015 High

   Established CEP85 as a centrosomal negative regulator of centrosome separation, answering how Nek2A activity is restrained during interphase.

   Evidence Co-IP, in vitro kinase assay, immunofluorescence, and siRNA/overexpression phenotyping with domain mapping in cells

   PMID:26220856

   Open questions at the time

   • Structural basis of the CEP85–Nek2A interface not defined
   • Mechanism by which PP1γ cooperates with CEP85 not resolved
   • How the inhibition is relieved at mitotic entry not addressed
2. 2018 High

   Defined the direct CEP85–STIL interface and showed it is required for STIL centriolar targeting, PLK4 activation, and daughter centriole assembly, placing CEP85 in the centriole biogenesis pathway.

   Evidence BioID proximity mapping, structural determination, structure-guided mutagenesis with in vivo rescue, and Co-IP

   PMID:29712910

   Open questions at the time

   • Temporal coordination between the STIL-binding and Nek2A-binding roles of CEP85 not addressed
   • Whether the same CEP85 molecules participate in both functions unknown
3. 2018 High

   Resolved how interphase inhibition of Nek2A is switched off, showing PLK1 phosphorylates CEP85 within a ternary complex to release active Nek2A and trigger disjunction at G2/M.

   Evidence Co-IP establishing ternary complex, in vitro kinase assays, phospho-specific analyses, and cell-based assays with mutant forms

   PMID:30611117

   Open questions at the time

   • Specific PLK1 phosphosites on CEP85 and their structural consequences not fully mapped
   • How phosphorylation selectively dissociates CEP85 from phospho-Nek2A but not unphosphorylated Nek2A unresolved
4. 2020 High

   Extended CEP85 function beyond the centrosome by showing the CEP85–STIL complex drives directional migration through PLK4-dependent leading-edge recruitment and ARP2 phosphorylation.

   Evidence Structure-guided mutagenesis, leading-edge localization, siRNA knockdown, ARP2 phosphorylation assays, and directed migration assays

   PMID:32107292

   Open questions at the time

   • Direct link between CEP85–STIL and ARP2 kinase not established
   • Whether this role is separable from centriolar duplication function unclear
5. 2025 Low

   Implicated CEP85 in macrophage phagocytosis, hinting at a function outside cell-division contexts.

   Evidence Overexpression in monocyte-derived macrophages with phagocytosis assay (preprint)

   Open questions at the time

   • Single overexpression assay in a preprint with no mechanistic pathway placement
   • No molecular partners or signaling readout identified
   • Not independently confirmed

• How CEP85 partitions its centriole-biogenesis (STIL/PLK4), centrosome-disjunction (Nek2A/PLK1/PP1γ), and migration roles across the cell cycle and cell types remains unresolved.
• No structural model integrating the STIL- and Nek2A-binding regions
• Spatiotemporal regulation distinguishing the functions not defined