DSN1

DSN1 is a core subunit of the MIS12 (Mis12c) kinetochore complex that bridges the inner centromere to the outer microtubule-binding machinery during mitosis [PMID:bio_10.1101_2025.06.03.657598]. Structurally, its N-terminal auto-inhibitory segment folds into two α-helices that engage the Mis12c head and occlude the binding sites for inner kinetochore subunits CENP-C (Mif2) and CENP-U (Ame1); Aurora B (Ipl1) phosphorylation of this segment relieves the auto-inhibition to strengthen inner-outer kinetochore connections, while C-terminal α-helical motifs of Dsn1 together with Mis12 and Nnf1 bind Knl1c and Ndc80c to assemble the KMN network [PMID:bio_10.1101_2025.06.03.657598]. DSN1 phosphorylation also cooperates with CENP-T phosphorylation to support a CENP-T–Mis12c interaction that ensures proper mitotic progression [PMID:bio_10.1101_2024.06.20.599825]. A germline-specific alternative splice isoform lacks the regulatory region required for Aurora kinase phosphorylation, producing constitutive centromere localization; ectopic somatic expression of this isoform causes chromosome segregation errors, and its elimination in mice disrupts oocyte maturation, early embryonic divisions, and fertility (PMID:39178843). DSN1 abundance is controlled at multiple levels: the Mub1/Ubr2 ubiquitin ligase ubiquitylates aberrant Dsn1 for proteasomal degradation as a quality-control mechanism (PMID:23408894), ESRRA directly activates DSN1 transcription upstream of a CDC25C–CDK1–Cyclin B1 axis (PMID:34131395), and METTL3-dependent m6A marks on DSN1 mRNA are read by SRSF9 to stabilize the transcript (PMID:35509101). In cancer cells DSN1 additionally stabilizes c-MYC by competing with FZR1 for binding, thereby attenuating FZR1-mediated c-MYC ubiquitination (PMID:41713835).

1. 2013 High

   Established that Dsn1 protein levels are actively policed at the kinetochore, identifying a ubiquitin-dependent quality control route for aberrant subunit.

   Evidence Kinetochore particle purification, Co-IP/mass spectrometry, and ubiquitylation assays with genetic deletion rescue in yeast

   PMID:23408894

   Open questions at the time

   • Does not define which structural features of Dsn1 mark it as aberrant
   • Mammalian conservation of Mub1/Ubr2-mediated control not addressed
2. 2021 Medium

   Identified ESRRA as a direct transcriptional activator of DSN1, placing DSN1 upstream of the CDC25C–CDK1–Cyclin B1 G2/M control axis.

   Evidence ChIP, dual-luciferase promoter assay, RNA-seq and flow cytometry with ESRRA knockdown

   PMID:34131395

   Open questions at the time

   • Single lab
   • Mechanistic link between DSN1 and CDC25C-CDK1-CyclinB1 not biochemically resolved
3. 2022 Medium

   Defined post-transcriptional control of DSN1 by an m6A-reader mechanism, explaining how DSN1 transcript stability is set.

   Evidence m6A affinity and qRT-PCR, RNA stability assays, dual-luciferase reporters with METTL3 knockdown

   PMID:35509101

   Open questions at the time

   • Single lab
   • Physiological/disease context of SRSF9-DSN1 regulation not established
4. 2024 High

   Showed that a germline-specific DSN1 splice isoform bypasses Aurora-dependent regulation, linking DSN1 phospho-regulation to mammalian fertility and chromosome segregation fidelity.

   Evidence Alternative splice identification, live-cell imaging, somatic overexpression phenotyping, and mouse knockout of the germline isoform

   PMID:38659852 PMID:39178843

   Open questions at the time

   • Why germline cells require phosphorylation-independent localization is unresolved
   • Structural basis of isoform behavior not directly determined
5. 2024 Medium

   Established an alternative CENP-T–Mis12c attachment route co-regulated by Dsn1 and CENP-T phosphorylation, complementing the CENP-C-dependent pathway.

   Evidence AlphaFold2-guided mutagenesis and viability/binding assays in DT40 cells lacking CENP-C–Mis12c interaction

   PMID:bio_10.1101_2024.06.20.599825

   Open questions at the time

   • Preprint, single lab
   • Relative contribution of CENP-T versus CENP-C pathways in normal cells not quantified
6. 2024 Low

   Reported a direct DSN1–CENPT interaction driving cell-cycle protein overproduction and chromosomal instability in hepatocellular carcinoma, suggesting an oncogenic dimension to DSN1 function.

   Evidence siRNA/shRNA knockdown, overexpression, co-immunoprecipitation, and xenograft model in HCC cells

   PMID:39560395

   Open questions at the time

   • Interaction inferred with limited mechanistic detail; no structural or reconstitution data
   • Single lab
7. 2025 High

   Provided the structural mechanism of DSN1 auto-inhibition, showing how its N-terminal segment occludes CENP-C/CENP-U binding until Aurora B phosphorylation licenses kinetochore assembly.

   Evidence Cryo-EM of the budding yeast KMN complex with biochemical binding and genetic validation

   PMID:bio_10.1101_2025.06.03.657598

   Open questions at the time

   • Preprint
   • Human KMN structural confirmation not provided
   • Dynamics of phosphorylation-triggered release not directly visualized
8. 2026 Medium

   Defined a non-kinetochore moonlighting role in which DSN1 stabilizes c-MYC by competing with FZR1, linking DSN1 to oncogenic protein homeostasis.

   Evidence Cycloheximide chase, proteasome inhibition, Co-IP, c-MYC rescue, and in vivo metastasis assays

   PMID:41713835

   Open questions at the time

   • Single lab
   • Whether this function depends on or is separable from kinetochore DSN1 is unknown
   • Structural basis of DSN1-FZR1 competition undefined

• How DSN1's canonical kinetochore role mechanistically connects to its proposed oncogenic functions (CENPT-driven instability, c-MYC stabilization) remains unresolved.
• No reconstitution distinguishing kinetochore versus cytoplasmic DSN1 pools
• Human structural data for auto-inhibition lacking
• Causality of DSN1 in human tumorigenesis not established by genetic models