CDCA2

CDCA2 (Repo-Man) is a chromatin-targeting regulatory subunit that recruits protein phosphatase PP1γ onto mitotic chromatin at anaphase onset and into interphase, coordinating chromosome architecture, mitotic exit, and nuclear reassembly (PMID:16492807, PMID:21820363). It uses functionally separable domains: a C-terminal domain that targets bulk chromatin and directs PP1-dependent dephosphorylation of mitotic histone H3 marks (H3T3ph, H3S10ph, H3S28ph), and an N-terminal domain that recruits nuclear envelope components Importin β and Nup153 in a PP1-independent manner (PMID:21514157, PMID:21820363). As the chromosome-bound PP1γ interactor, the complex selectively reverses Haspin-driven H3T3ph and thereby modulates centromeric targeting of Aurora B and its substrate MCAK, while opposing a condensin-cooperating chromosome-compacting activity to preserve mitotic chromosome structure (PMID:16998479, PMID:21514157). Its chromosomal recruitment is set by a phospho-switch in which Aurora B phosphorylates Repo-Man at S893 to block histone-mediated targeting and dissociate PP1γ, opposed by PP2A-mediated dephosphorylation, forming a bistable feedback loop that delimits Aurora B activity (PMID:23746640, PMID:32938714). Beyond histones, the PP1/Repo-Man complex dephosphorylates and inactivates ATM to suppress DNA-damage checkpoint signaling (PMID:20188555), dephosphorylates lamin A at S22 during mitotic exit through a SUMOylation-dependent interaction required for proper nuclear envelope reformation (PMID:35414260), and in interphase promotes peripheral heterochromatin formation by dephosphorylating H3S28 to enable HP1 binding and H3K27me3 recruitment (PMID:28091603). In cancer cells CDCA2 acts as an oncogenic stabilizer of MYC/MYCN proteins and is itself a direct MYC target gene, establishing a positive feedback loop whose disruption reduces viability of multiple tumor types (PMID:41844234).

1. 2006 High

   Established CDCA2 as a dedicated PP1γ-targeting subunit that delivers the phosphatase specifically to chromatin, defining how a generic phosphatase achieves spatial specificity in mitosis.

   Evidence Proteomics, reciprocal Co-IP, PP1-binding domain mutagenesis, and live-cell imaging in human cells

   PMID:16492807

   Open questions at the time

   • Histone and non-histone substrates not yet identified
   • Mechanism of chromatin targeting not yet mapped to a domain
2. 2006 High

   Showed that Repo-Man/PP1 inactivates a chromosome-compacting activity cooperating with condensin, placing the complex within mitotic chromosome architecture control.

   Evidence Conditional SMC2 knockout in chicken DT40 cells with dominant-negative epistasis and live-cell imaging

   PMID:16998479

   Open questions at the time

   • Molecular identity of the 'RCA' activity unresolved
   • Direct phosphatase substrates underlying compaction control not defined
3. 2010 High

   Extended Repo-Man function beyond chromosome architecture by showing the complex dephosphorylates and inactivates ATM to restrain DNA-damage checkpoint signaling.

   Evidence Xenopus egg extract biochemistry, domain mutagenesis, reciprocal Co-IP, validated in human cells

   PMID:20188555

   Open questions at the time

   • ATM dephosphorylation sites not pinpointed
   • Physiological context where this suppression dominates not defined
4. 2011 High

   Identified the histone H3 substrates of the complex and connected H3T3ph reversal to Aurora B centromeric targeting, linking phosphatase activity to kinase positioning.

   Evidence In vitro phosphatase assays, RNAi, mutagenesis, and Aurora B/MCAK localization imaging

   PMID:21514157

   Open questions at the time

   • Direct versus indirect dephosphorylation of H3S10/H3T11 not fully separated
   • Quantitative contribution to Aurora B gradient unresolved
5. 2011 High

   Resolved the protein into two separable functional modules — a chromatin-targeting/H3-dephosphorylating C-terminus and a PP1-independent nuclear envelope-recruiting N-terminus — explaining its dual roles at mitotic exit.

   Evidence Domain deletion/mutation, live-cell imaging, Co-IP, and fractionation

   PMID:21820363

   Open questions at the time

   • How the two domains are temporally coordinated within anaphase unclear
   • Structural basis of Importin β/Nup153 recruitment not defined
6. 2012 Medium

   Showed Repo-Man (with Sds22) counteracts Aurora B phosphorylation of the kinetochore component Dsn1, tying its activity to faithful chromosome segregation.

   Evidence Phosphorylation-biosensor RNAi screen and live-cell imaging

   PMID:22801782

   Open questions at the time

   • Direct dephosphorylation of Dsn1 not biochemically demonstrated
   • Relative contributions of Repo-Man and Sds22 not separated
7. 2013 High

   Defined the phospho-switch governing Repo-Man recruitment: Aurora B phosphorylation at S893 blocks chromatin targeting and PP2A reverses it, establishing a bistable kinase/phosphatase feedback loop.

   Evidence S893 mutagenesis, in vitro kinase assay, reciprocal Co-IP, and functional rescue

   PMID:23746640

   Open questions at the time

   • Quantitative thresholds of the bistable switch not modeled
   • Whether other Aurora B sites contribute not excluded
8. 2013 Medium

   Provided cancer-relevant loss-of-function evidence that CDCA2 prevents ATM-dependent p53-p21 signaling and supports proliferation, connecting its checkpoint-suppressing role to tumor cell survival.

   Evidence shRNA knockdown with cell-cycle flow cytometry and CDK-inhibitor Western blots in oral squamous carcinoma cells

   PMID:23418564

   Open questions at the time

   • Direct link between CDCA2 phosphatase activity and p21/p27 induction not biochemically shown
   • Single cancer cell context
9. 2017 High

   Demonstrated an interphase chromatin role: Repo-Man/PP1 dephosphorylates H3S28 at the nuclear periphery to promote HP1 binding, H3K27me3 recruitment, and heterochromatin organization.

   Evidence ChIP-seq, RNAi, immunofluorescence, and gene-expression readouts

   PMID:28091603

   Open questions at the time

   • Mechanism coupling Nup153 anchoring to substrate selection unclear
   • Causality between H3S28 dephosphorylation and H3K27me3 deposition not fully dissected
10. 2017 Medium

    Linked Repo-Man/PP1 to spindle orientation through cortical NuMA accumulation, with p37/UBXN2B as a negative regulator, broadening its mitotic remit beyond chromatin.

    Evidence RNAi, immunofluorescence, live-cell imaging, and epistasis with Gαi/Aurora A/PP2A inhibitors

    PMID:29222185

    Open questions at the time

    • Direct phosphatase substrate at the cortex not identified
    • Mechanism by which p37 inhibits the complex undefined
11. 2020 Medium

    Reinforced that Aurora B phosphorylation disrupts the PP1γ-Repo-Man interaction itself, controlling chromosome condensation dynamics through PP1γ retention.

    Evidence Co-IP, phospho-resistant mutant overexpression, Aurora B inhibition, and immunofluorescence

    PMID:32938714

    Open questions at the time

    • Single-lab confirmation of S893-specific effect on PP1γ binding
    • Structural basis of phospho-disrupted PP1 binding unknown
12. 2022 High

    Identified lamin A S22 as a mitotic-exit substrate and SUMOylation of Repo-Man as the targeting mechanism, mechanistically connecting the complex to nuclear envelope reformation.

    Evidence In vitro/in vivo Co-IP, SUMOylation-deficient mutant rescue, phospho-specific Western blots, and NE-defect imaging

    PMID:35414260

    Open questions at the time

    • SUMO sites on Repo-Man not mapped
    • Whether SUMOylation regulates other substrate interactions unknown
13. 2023 Medium

    Revealed a tumor-promoting mechanism in which CDCA2 stabilizes AURKA by acting on the E3 ligase SMURF1 to block its ubiquitin-dependent degradation, driving melanoma proliferation.

    Evidence Co-IP, ubiquitination and protein stability assays, epistasis, and in vitro/in vivo tumor models

    PMID:37196484

    Open questions at the time

    • Whether PP1 phosphatase activity is required for AURKA stabilization unclear
    • Direct CDCA2-SMURF1 biochemical mechanism incompletely defined
14. 2026 Medium

    Established CDCA2 as both a stabilizer of MYC/MYCN proteins and a direct MYC target gene, defining an oncogenic positive feedback loop whose disruption reduces tumor cell viability.

    Evidence RNAi, degron degradation, proximity ligation, ChIP, and promoter mutation studies across multiple cancer cell types

    PMID:41844234

    Open questions at the time

    • Mechanism by which CDCA2 stabilizes MYC/MYCN not biochemically resolved
    • Whether stabilization depends on PP1 or phosphatase activity unknown
15. 2025 Medium

    Showed PHD1-mediated prolyl hydroxylation of Repo-Man at P604 is required for PP2A-B56γ interaction and proper mitotic progression, adding a PTM-controlled layer to phosphatase complex assembly.

    Evidence Mass spectrometry PTM identification, P604A mutant rescue, Co-IP for PP2A-B56γ, and live-cell imaging (preprint)

    PMID:bio_10.1101_2025.05.06.652400

    Open questions at the time

    • Preprint, single lab not yet peer-reviewed
    • How oxygen-sensitive hydroxylation integrates with the Aurora B/PP2A switch unclear

• How CDCA2's well-defined mitotic phosphatase-targeting activity mechanistically connects to its oncogenic MYC/MYCN and AURKA stabilization functions — and whether these depend on PP1 catalytic activity — remains unresolved.
• No structural model of the chromatin-bound PP1γ/Repo-Man complex
• Biochemical mechanism of MYC/MYCN and AURKA protein stabilization undefined
• Whether oncogenic roles require phosphatase activity untested