SKA1: Spindle and Kinetochore Associated Complex Subunit 1
A key regulator of mitotic progression and chromosome segregation, implicated in cancer and genomic instability.
Gene Information Card
| Symbol | SKA1 |
|---|---|
| Full Name | Spindle and Kinetochore Associated Complex Subunit 1 |
| Gene Type | Protein coding |
| Chromosomal Location | 18q21.1 |
| NCBI Gene ID | 220134 ncbi.nlm.nih.gov/gene/220134 |
| Ensembl ID | ENSG00000154839 |
| UniProt ID | Q96BD8 |
| OMIM ID | 616788 |
| HGNC ID | 26403 |
| Aliases | C18orf24, FLJ12884, SKA1 complex subunit 1 |
Description
SKA1 encodes a component of the spindle and kinetochore-associated (SKA) complex, which is essential for proper chromosome segregation during mitosis. The SKA complex stabilizes kinetochore-microtubule attachments and is required for the spindle checkpoint silencing and anaphase onset. SKA1 is overexpressed in various cancers and its dysregulation contributes to aneuploidy and tumorigenesis.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Breast cancer | Overexpression of SKA1 promotes cell proliferation and migration; knockdown reduces tumor growth in xenograft models. | PMID: 25944712 |
| Colorectal cancer | SKA1 upregulation correlates with poor prognosis; silencing induces mitotic arrest and apoptosis. | PMID: 29351287 |
| Hepatocellular carcinoma | High SKA1 expression associated with metastasis and shorter survival; promotes EMT via Wnt/β-catenin signaling. | PMID: 30351358 |
| Lung adenocarcinoma | SKA1 amplification and overexpression linked to chromosomal instability and poor outcome. | PMID: 31570759 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 15.2 | Medium |
| Bone marrow | 10.8 | Medium |
| Lymph node | 9.5 | Medium |
| Spleen | 8.1 | Low |
| Brain | 2.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 12.4 | Cervical cancer cell line; high expression |
| MCF7 | 9.8 | Breast cancer cell line; moderate expression |
| A549 | 11.1 | Lung cancer cell line; high expression |
| HCT116 | 10.5 | Colorectal cancer cell line; moderate expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.374C>T (p.Thr125Met) | Missense | <0.01% | Unknown; rare variant in COSMIC |
| c.487G>A (p.Glu163Lys) | Missense | <0.01% | Unknown; rare variant in COSMIC |
| Amplification | Copy number gain | 5-10% in breast cancer | Increased SKA1 expression; associated with poor prognosis |
Mutation functional classification
Loss of Function (LOF)
No confirmed loss-of-function mutations reported in SKA1; complete loss is likely lethal due to essential mitotic function.
Gain of Function (GOF)
Overexpression and amplification are common in cancers, suggesting a gain-of-function role in promoting proliferation and genomic instability.
Dominant Negative (DN)
No dominant-negative mutations described for SKA1.
View complete mutation data：
Gene Ontology (GO)
| • kinetochore (GO:0000776) | • spindle (GO:0005819) |
| • chromosome segregation (GO:0007059) | • cell division (GO:0051301) |
| • microtubule binding (GO:0008017) | • midbody (GO:0030496) |
Pathways
• Cell Cycle
• Mitotic (Reactome: R-HSA-69278)
• Mitotic Prometaphase (Reactome: R-HSA-68877)
• Resolution of Sister Chromatid Cohesion (Reactome: R-HSA-2500257)
• Kinetochore-Microtubule Interactions (Reactome: R-HSA-141444)
Protein Summary
SKA1 is a 35 kDa protein that forms a heterotrimeric complex with SKA2 and SKA3. The SKA complex localizes to kinetochores from prometaphase through anaphase, where it directly binds microtubules and stabilizes end-on attachments. SKA1 contains a coiled-coil domain essential for complex assembly and microtubule binding. Its overexpression in multiple cancer types promotes mitotic slippage, aneuploidy, and resistance to anti-mitotic drugs.
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