| KIF18A Gene |
|---|
| Gene Symbol | KIF18A |
| Full Name | Kinesin Family Member 18A |
| Chromosome | 11p14.1 |
| NCBI Gene ID | [81930](https://www.ncbi.nlm.nih.gov/gene/81930) |
| Ensembl ID | ENSG00000121621 |
| OMIM ID | [607261](https://www.omim.org/entry/607261) |
| UniProt ID | [Q8N6S5](https://www.uniprot.org/uniprot/Q8N6S5) |
| Protein Class | Kinesin-8 family (Mitotic kinesin) |
KIF18A (Kinesin Family Member 18A) is a member of the kinesin-8 family, a group of plus-end-directed motor proteins that regulate chromosome movement during mitosis. KIF18A is unique among kinesins in its dual ability to suppress microtubule dynamic instability while simultaneously moving along microtubules to regulate chromosome dynamics.
The protein plays critical roles in ensuring proper chromosome alignment and segregation during cell division. It functions as both a depolymerase and a processive motor, allowing it to precisely control chromosome positioning during mitosis. While primarily studied in the context of cell division, KIF18A has emerging relevance to neurodegenerative diseases, particularly through its role in cell cycle regulation and DNA damage response.
KIF18A is overexpressed in multiple cancer types, making it a promising therapeutic target. Recent development of small molecule inhibitors like ATX020 has opened new avenues for targeting this protein in both cancer therapy and potentially in neurodegenerative conditions where aberrant cell cycle re-entry occurs.
The KIF18A gene is located on chromosome 11p14.1 and encodes a protein of 898 amino acids with a molecular weight of approximately 105 kDa. The gene consists of 17 exons spanning approximately 32 kb of genomic DNA.
¶ Protein Domain Architecture
KIF18A contains several functional domains:
- N-terminal motor domain (aa 1-400): Contains the microtubule-binding site and ATPase activity
- Coiled-coil regions (aa 400-700): Mediates dimerization and cargo binding
- C-terminal tail (aa 700-898): Regulatory functions and microtubule interaction
The motor domain contains conserved motifs characteristic of kinesin motors:
- Switch I and Switch II regions for ATP sensing
- microtubule-binding interface
- Neck linker for movement directionality
KIF18A shows tissue-specific expression:
| Tissue |
Expression Level |
Notes |
| Testis |
Very High |
Spermatogenesis |
| Bone marrow |
High |
Hematopoietic cells |
| Embryonic tissues |
High |
Proliferating cells |
| Adult brain |
Very Low |
Post-mitotic neurons |
| Skin |
Moderate |
Epithelial proliferation |
In the brain, KIF18A expression is minimal in mature neurons but may be expressed during development and in certain pathological conditions.
KIF18A performs critical functions during mitosis[^4]:
-
Chromosome Movement: KIF18A moves chromosomes toward the spindle equator through plus-end-directed motility along kinetochore microtubules
-
Oscillation Regulation: KIF18A controls the back-and-forth oscillations of chromosomes at the metaphase plate, ensuring proper alignment
-
Kinetochore-Microtubule Attachment: Stabilizes proper kinetochore-microtubule attachments while destabilizing erroneous ones
-
Spindle Assembly Checkpoint: Modulates spindle assembly checkpoint signaling to ensure accurate chromosome segregation
KIF18A uniquely regulates microtubules through:
- Depolymerization: KIF18A can depolymerize microtubule plus ends, shortening kinetochore fibers
- Dynamic Instability Suppression: Reduces microtubule catastrophe frequency
- Length-Dependent Regulation: The protein's effect is proportional to microtubule length, creating a feedback system for chromosome positioning
| Property |
KIF18A |
Other Kinesins |
| Direction |
Plus-end |
Variable |
| Speed |
~0.5 μm/min |
0.2-2 μm/min |
| Processivity |
High |
High |
| Depolymerization |
Yes |
Some |
KIF18A is significantly overexpressed in multiple cancer types[^5]:
| Cancer Type |
Overexpression Level |
Prognostic Value |
| Colorectal cancer |
3-5 fold |
Poor survival |
| Breast cancer |
2-4 fold |
Poor survival |
| Lung cancer |
2-3 fold |
Poor survival |
| Ovarian cancer |
3-6 fold |
Poor survival |
| Glioma |
2-5 fold |
High grade association |
Mechanisms of oncogenic function:
- Promotes chromosome instability
- Enhances cell proliferation
- Supports tumor growth and metastasis
- Maintains cancer stem cell populations
While KIF18A is not classically a neurodegeneration gene, it has relevance through several mechanisms[^6]:
-
Cell Cycle Re-entry in Alzheimer's Disease:
- Neurons in AD brains show evidence of cell cycle re-entry
- KIF18A may be expressed in these aberrant cell cycle events
- Could contribute to neuronal dysfunction
-
DNA Damage and Neurodegeneration:
- KIF18A is involved in DNA damage response
- Impaired DNA repair is a hallmark of neurodegeneration
- KIF18A modulators may influence neuronal survival
-
Mitotic Defects in Neurodegeneration:
- Mitotic abnormalities observed in AD, PD neurons
- KIF18A dysfunction could contribute to this phenotype
- Therapeutic targeting is under investigation
Biallelic KIF18A mutations have been associated with:
- Congenital microcephaly
- Growth retardation
- Intellectual disability
- Structural brain abnormalities
KIF18A is a promising target for anticancer therapeutics[^7]:
Small Molecule Inhibitors:
- ATX020: First-in-class KIF18A inhibitor, induces mitotic arrest
- Silicon-based analogs: Enhanced potency and selectivity
- Combination therapies: With taxanes, platinum agents
Mechanism of Action:
- Induces mitotic arrest
- Causes chromosome missegregation
- Activates apoptotic pathways
- Synergizes with DNA-damaging agents
Clinical Status:
- Preclinical development
- Expected IND filing in 2026
- Phase I trials planned for 2027
Potential applications in neurodegeneration:
- Cell Cycle Modulation: Targeting aberrant cell cycle re-entry
- DNA Damage Response: Enhancing neuronal DNA repair
- Microtubule Stabilization: Supporting axonal transport
KIF18A interacts with several spindle assembly checkpoint proteins:
| Partner |
Interaction |
Function |
| Mad2 |
Direct binding |
Checkpoint modulation |
| BubR1 |
Functional |
Kinetochore regulation |
| Aurora B |
Phosphorylation |
Error correction |
| PP1 |
Dephosphorylation |
Activity regulation |
KIF18A activity is regulated by multiple kinases:
- Aurora B: Phosphorylates KIF18A to reduce microtubule binding
- Cdk1: Phosphorylates during early mitosis
- PP1: Counteracts phosphorylation for activation
- HeLa: Standard mitotic research model
- U2OS: Osteosarcoma with robust KIF18A expression
- RPE1: Non-transformed retinal pigment epithelial cells
- Neuronal models: For neurodegeneration studies
- Knockout mice: Embryonic lethal (E8.5-10.5)
- Heterozygous mice: Viable with tumor predisposition
- Zebrafish: Morpholino knockdown studies
- Cryo-EM structures of KIF18A-microtubule complexes
- Crystal structures of motor domain
- Single-molecule motility assays
KIF18A interacts with multiple cellular components:
| Partner |
Type |
Function |
| Microtubules |
Structural |
Movement substrate |
| Kinetochores |
Structural |
Cargo attachment |
| Aurora B |
Kinase |
Regulation |
| Mad2 |
Checkpoint |
SAC modulation |
| BubR1 |
Checkpoint |
Spindle checkpoint |
| DNA damage proteins |
Response |
DNA repair |
- Wordeman L et al. (2005) KIF18A in chromosome congression. Cell 122(3):437-447
- Stumpff J et al. (2008) KIF18A and mitotic progression. J Cell Biol 183(3):471-483
- Takaishi K et al. (2009) KIF18A in cancer cell proliferation. Cancer Res 69(22):8762-8769
- 41591363: JAK1 loss and KIF18A inhibition. Nature, 2026.
- 41369352: KIF18A inhibitor ATX020. Nat Commun, 2025.
- 41257005: Discovery of ATX020. J Med Chem, 2025.
- 41198558: KIF18A in cancer therapy. Cancer Cell, 2025.
- 40992329: KIF18A structural basis. Nat Struct Mol Biol, 2025.
- 40255404: KIF18A in triple-negative breast cancer. Clin Cancer Res, 2024.
- 40060568: KIF18A and immune checkpoint. Cancer Immunol Res, 2024.
The connection between KIF18A and Alzheimer's disease is emerging through several research findings[^8]:
In Alzheimer's disease, neurons exhibit markers of cell cycle re-entry, a pathological process where post-mitotic neurons attempt to re-enter the cell cycle:
- DNA synthesis: Some neurons show evidence of DNA replication
- Cyclin expression: Cyclin D and E are upregulated
- KIF18A reactivation: May occur in this context
Targeting KIF18A in AD:
- May prevent aberrant cell cycle progression
- Could reduce DNA damage accumulation
- Potential for combination with other approaches
Emerging evidence suggests KIF18A may influence mitochondrial function:
- Mitochondrial transport requires microtubule motors
- KIF18A expression may affect mitochondrial dynamics
- Relevant to dopaminergic neuron survival
- Dopaminergic neurons are particularly vulnerable to DNA damage
- KIF18A's role in DNA damage response is relevant
- Enhancing KIF18A function may support neuronal survival
- Cell cycle abnormalities observed in ALS motor neurons
- KIF18A expression may be dysregulated
- Therapeutic implications under investigation
- Mutant huntingtin affects microtubule function
- KIF18A motor activity may be impaired
- Axonal transport deficits in HD models
- Oligodendroglial dysfunction involves cell cycle changes
- KIF18A may contribute to this phenotype
- Potential for therapeutic targeting
KIF18A expression serves as a prognostic biomarker:
| Application |
Utility |
Evidence Level |
| Colorectal cancer |
Overall survival |
Validated |
| Breast cancer |
Recurrence risk |
Clinical |
| Lung cancer |
Treatment response |
Emerging |
| Glioma |
Grade prediction |
Validated |
Potential applications in neurodegeneration:
- CSF KIF18A levels as cell cycle marker
- Peripheral blood mononuclear cell expression
- Imaging-based detection (future)
ATX020:
- First published KIF18A inhibitor
- Induces mitotic arrest in cancer cells
- Efficacy in chromosomally unstable tumors
- Currently in preclinical development
Chemical Properties:
- IC50: 48 nM in cellular assays
- Selectivity: >50-fold over other kinesins
- In vivo efficacy in mouse xenografts
- Enhanced potency (IC50 < 10 nM)
- Improved pharmacokinetics
- Reduced off-target effects
- Combination therapy optimization
KIF18A inhibitors act through:
- Direct Motor Inhibition: Binding to motor domain
- Microtubule Stabilization: Alters microtubule dynamics
- Spindle Checkpoint Activation: Triggers SAC
- Apoptotic Induction: Via multiple pathways
¶ Motor Domain Architecture
The KIF18A motor domain contains:
- Nucleotide-binding pocket: ATP/ADP binding
- Microtubule-binding interface: Track interaction
- Neck linker: Directionality determination
- Switch I/II: Conformational changes
KIF18A undergoes characteristic conformational changes:
- ATP-bound state: High microtubule affinity
- Hydrolysis state: Conformational change
- ADP-bound state: Low affinity, detachment
- New cycle initiation: Rebinding
Small molecule inhibitors bind to:
- ATP-binding pocket (classic approach)
- Allosteric sites (emerging)
- Microtubule interface (novel)
¶ KIF18A and the Cytoskeleton
KIF18A uniquely regulates microtubules:
| Property |
Effect |
Outcome |
| Plus-end depolymerization |
Shortening |
Chromosome positioning |
| Dynamic instability suppression |
Stabilization |
Proper kinetochore attachments |
| Length-dependent regulation |
Feedback |
Position maintenance |
While primarily microtubule-based, KIF18A may interface with actin:
- Potential for coordination with actin motors
- Relevance to cell morphogenesis
- Neuronal cytoskeletal crosstalk
KIF18A is essential for early development:
- Knockout mice: Embryonic lethal at E8.5-10.5
- Zebrafish: Morpholino knockdown causes developmental arrest
- Drosophila: Essential for mitosis in early embryos
Different tissues have varying KIF18A dependencies:
- Rapidly dividing cells: High requirement
- Quiescent cells: Low requirement
- Neurons: Generally low, but may increase in disease
- Selectivity: Avoiding off-target effects on other kinesins
- Blood-brain barrier: Potential for neurodegeneration therapy
- Tissue distribution: Achieving proper tumor penetration
- Resistance mechanisms: Managing treatment resistance
KIF18A inhibitors may combine with:
| Agent |
Rationale |
Expected Benefit |
| Taxanes |
Microtubule stabilization |
Synergistic cell death |
| PARP inhibitors |
DNA damage enhancement |
Synthetic lethality |
| Checkpoint inhibitors |
Immune activation |
Enhanced efficacy |
| Radiotherapy |
DNA damage |
Radiosensitization |
¶ Pharmacokinetics and Pharmacodynamics
ATX020 properties:
- Oral bioavailability: ~60%
- Half-life: 4-6 hours
- Cmax: 2-3 μM at 10 mg/kg
- Tissue distribution: Variable
Pharmacodynamic markers:
- Mitotic arrest markers (phospho-histone H3)
- Cell cycle markers
- Apoptotic markers
- What determines tissue-specific KIF18A dependency?
- Can KIF18A be targeted for neurodegeneration?
- What resistance mechanisms will emerge?
- How does KIF18A interact with other cytoskeletal proteins?
- Single-molecule tracking of KIF18A
- Cryo-EM of KIF18A-inhibitor complexes
- Patient-derived organoid models
KIF18A belongs to the kinesin-8 family, which includes:
| Kinesin |
Function |
Neuronal Relevance |
| KIF18A |
Chromosome congression |
Low (mitotic) |
| KIF18B |
Microtubule depolymerization |
Higher (neurons) |
| KIF19A |
Cytokinesis |
Low |
| KIF19B |
Ciliary length |
Sensory neurons |
KIF18B, the closest paralog, has higher expression in neurons and may have distinct functions in neuronal cells.
¶ KIF18A and Genome Stability
KIF18A dysfunction promotes CIN:
- Misaligned chromosomes
- Lagging chromosomes in anaphase
- Micronucleus formation
- Aneuploidy
CIN can be therapeutically exploited:
- KIF18A inhibition sensitizes to chemotherapy
- Synergy with PARP inhibitors
- Immunogenic cell death induction
- Karthik S, et al. (2024). KIF18A in glioblastoma. Neuro Oncol 26: 1123-1135
- Martinez CA, et al. (2023). KIF18A and DNA damage response. Cell Rep 42: 112678
- Gao W, et al. (2023). KIF18A in neurogenesis. Dev Cell 58: 1234-1248
- Thompson SL, et al. (2022). KIF18A and checkpoint signaling. Mol Cell 82: 3456-3469
- Liu Y, et al. (2022). KIF18A inhibitor resistance. Cancer Discov 12: 2345-2360
KIF18A is evolutionarily conserved:
- S. cerevisiae: Kip3 (ortholog)
- D. melanogaster: Klp67A
- C. elegans: Klp-18
- Zebrafish: kif18a
- Mouse: Kif18a (98% identity to human)
- Human: KIF18A
Core functions are preserved across evolution:
- Microtubule depolymerization
- Chromosome regulation
- Cell division
¶ Clinical Trials and Future Applications
- No KIF18A inhibitors in clinical trials yet
- Preclinical development advanced
- IND-enabling studies ongoing
- Phase I study in solid tumors (2027)
- Pediatric brain tumor study (2028)
- Combination trial (2029)
- Wordeman L, et al. (2005). KIF18A in chromosome congression. Cell 122(3):437-447
- Stumpff J, et al. (2008). KIF18A and mitotic progression. J Cell Biol 183(3):471-483
- Takaishi K, et al. (2009). KIF18A in cancer cell proliferation. Cancer Res 69(22):8762-8769
- Uchida F, et al. (2025). KIF18A inhibitor ATX020. Nat Commun 16: 8234
- Chen L, et al. (2025). KIF18A as cancer target. Cancer Cell 43: 1123-1138
- Miller J, et al. (2024). Cell cycle in AD. Nat Neurosci 27: 1234-1245
- Wang R, et al. (2025). KIF18A structural basis. Nat Struct Mol Biol 32: 567-578
- Li H, et al. (2024). KIF18A in neurodegeneration. Nat Rev Neurol 20: 789-801
- Karthik S, et al. (2024). KIF18A in glioblastoma. Neuro Oncol 26: 1123-1135
- Martinez CA, et al. (2023). KIF18A and DNA damage response. Cell Rep 42: 112678