CENPN

CENP-N is a constitutive centromere component that establishes the molecular basis for selective recognition of CENP-A nucleosomes, thereby seeding kinetochore assembly and licensing accurate chromosome segregation (PMID:19543270). It distinguishes CENP-A from canonical H3 chromatin by decoding the CENP-A-specific L1/RG loop through charge and shape complementarity while clamping an adjacent segment of nucleosomal DNA, and stable centromere recruitment additionally requires a coincident contact with nucleosome-bound CENP-C (PMID:29280735, PMID:29269420). Through these contacts CENP-N is required for centromeric loading of nascent CENP-A and for downstream recruitment of CCAN members CENP-H, CENP-I, and CENP-K, with binding-deficient mutants acting dominant-negatively (PMID:19543270). CENP-N centromere association is cell-cycle restricted—enriched and stably bound during S/G2 but largely absent in mitosis and G1—because the CENP-A RG loop is concealed within a compact chromatin state and becomes exposed only upon a G1/S conformational switch to an open configuration (PMID:25943375, PMID:22100916). Beyond reading individual nucleosomes, CENP-N drives higher-order centromeric chromatin compaction by using its α6 helix to bridge the DNA of neighboring nucleosomes into stacked arrays (PMID:35422519), and its interaction with CENP-L is modulated by CDK1-mediated mitotic phosphorylation, which is required for proper chromosome alignment and CCAN organization (PMID:37365681). A separate body of cancer-cell work places CENP-N in transcriptional and signaling circuits—suppressing autophagy via p-CREB/VAMP8 and promoting tumor invasion through a STAT3/USP37 axis (PMID:37776538, PMID:40458725)—but these activities are documented only in specific tumor contexts and their mechanistic relationship to its centromeric function is uncharacterized in the available corpus.

1. 2009 High

   Established that CENP-N is the centromere protein that selectively reads CENP-A nucleosomes and acts upstream of the CCAN, answering how the centromere distinguishes CENP-A chromatin from bulk H3 chromatin.

   Evidence In vitro nucleosome binding assays with mutagenesis plus siRNA depletion and fluorescence microscopy in human cells

   PMID:19543270

   Open questions at the time

   • Structural basis of CENP-A discrimination not yet resolved
   • Direct contact residues on CENP-A undefined at this stage
2. 2011 High

   Defined the cell-cycle dynamics of CENP-N at centromeres, showing it is a transient S/G2 factor rather than a constitutively bound subunit, and positioned it as a fidelity factor during centromeric replication.

   Evidence FRET and FRAP live-cell imaging with cell-cycle markers

   PMID:22100916

   Open questions at the time

   • Molecular trigger for the timed loading/dissociation not identified here
   • Functional consequence of S-phase loading on segregation not directly tested
3. 2015 High

   Explained the mechanism of cell-cycle-regulated recruitment by linking the CENP-A RG loop to a switchable compact-versus-open centromeric chromatin state that conceals or exposes the CENP-N binding determinant.

   Evidence Biochemical chromatin compaction assays, RG-loop mutagenesis, and cell-cycle synchronization with microscopy

   PMID:25943375

   Open questions at the time

   • Factors driving the compaction switch not fully defined
   • Single-lab structural model of the ladder-like state
4. 2017 High

   Resolved the structural code for CENP-A recognition: cryo-EM showed CENP-N decodes the CENP-A L1 loop via charge/shape complementarity stabilized by nucleosomal DNA, with CENP-C providing a coincident anchoring contact for stable recruitment.

   Evidence Two independent cryo-EM structures with biophysical binding assays, mutagenesis, and cross-species L1-loop residue-swapping (eLife and Science)

   PMID:29269420 PMID:29280735

   Open questions at the time

   • How CENP-C and CENP-A contacts are temporally coordinated unclear
   • Higher-order chromatin role not addressed by mononucleosome structures
5. 2022 High

   Extended CENP-N's role beyond single-nucleosome recognition by showing it physically compacts centromeric chromatin into stacked nucleosome arrays through its α6 helix.

   Evidence Cryo-EM of nucleosome stacks, biophysical characterization, α6-helix mutagenesis, and cell-based compaction assays

   PMID:35422519

   Open questions at the time

   • How compaction is reconciled with the open-state requirement for recruitment unresolved
   • Functional consequence of stacking for kinetochore assembly not directly tested
6. 2023 Medium

   Identified post-translational control of CENP-N, showing CDK1 phosphorylation modulates the CENP-L–CENP-N interaction to enable proper chromosome alignment and CCAN organization.

   Evidence Mass spectrometry phosphosite mapping, CDK1 kinase assays, phosphomutant cell biology, and spindle assembly checkpoint readouts

   PMID:37365681

   Open questions at the time

   • Full mutagenesis rescue controls not detailed in abstract
   • Specific phosphosites and their structural effect on CENP-L binding not defined
7. 2019 Medium

   Addressed CENP-N stability regulation, identifying HSC70 as a chaperone that protects CENP-N from ubiquitin-proteasome degradation to control its cell-cycle turnover at centromeres.

   Evidence RNAi, immunofluorescence localization, affinity purification/MS, Co-IP, and proteasome inhibition in silkworm (Bombyx mori)

   PMID:31756960

   Open questions at the time

   • Relevance to mammalian CENP-N uncertain given holocentric, CENP-A/C-divergent system
   • Single lab, single Co-IP for HSC70 interaction
8. 2024 Medium

   Implicated CENP-N in a non-centromeric transcriptional circuit, showing it suppresses autophagy by blocking p-CREB nuclear translocation and VAMP8 transcription in nasopharyngeal carcinoma.

   Evidence Knockdown, transcriptome sequencing, ChIP for p-CREB at the VAMP8 promoter, autophagy assays, and xenograft model

   PMID:37776538

   Open questions at the time

   • Mechanistic link to CENP-N's centromeric function unclear
   • How CENP-N controls p-CREB localization not defined
9. 2025 Medium

   Defined a CENP-N/STAT3/USP37 signaling axis, with direct CENP-N–STAT3 binding promoting STAT3 phosphorylation/nuclear translocation to drive tumor invasion and metastasis.

   Evidence Reciprocal Co-IP, GST pull-down, truncation mapping, luciferase reporter, ChIP, and xenograft model in NPC cells

   PMID:40458725

   Open questions at the time

   • Single-lab study
   • How a centromeric protein engages cytoplasmic/nuclear STAT3 signaling mechanistically unresolved
10. 2024 Low

    Reported additional tumor-context partners (SEPT9, MDM2) linking CENP-N to glycolysis and p53 signaling.

    Evidence Co-IP, methylation-specific PCR, ChIP, bioinformatic enrichment, and in vitro/in vivo functional assays in CRC and pancreatic cancer

    PMID:39424682 PMID:39649279

    Open questions at the time

    • Single Co-IP interactions without reconstitution
    • Methyltransferase mechanism for SEPT9 unspecified; p53 link relies on enrichment analysis

• How CENP-N's well-defined centromeric/kinetochore activity mechanistically connects to the reported cytoplasmic and transcriptional cancer signaling roles remains unresolved.
• No unified model linking centromere function to STAT3/CREB/MDM2 signaling
• Tumor-context partners not validated in normal cell physiology
• Whether signaling roles require chromatin binding is untested