KIF18A Gene — Kinesin Family Member 18A

KIF18A Gene — Kinesin Family Member 18A

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#f0f0f0; text-align:center; font-size:1.1em;">KIF18A Gene</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>KIF18A</td></tr>
<tr><td><strong>Full Name</strong></td><td>Kinesin Family Member 18A</td></tr>
<tr><td><strong>Chromosome</strong></td><td>11p14.1</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[81930](https://www.ncbi.nlm.nih.gov/gene/81930)</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000121621</td></tr>
<tr><td><strong>OMIM ID</strong></td><td>[607261](https://www.omim.org/entry/607261)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q8N6S5](https://www.uniprot.org/uniprot/Q8N6S5)</td></tr>
<tr><td><strong>Protein Class</strong></td><td>Kinesin-8 family (Mitotic kinesin)</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

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](/mechanisms/mitosis). KIF18A is unique among kinesins in its dual ability to suppress microtubule dynamic instability while simultaneously moving along microtubules to regulate chromosome dynamics[^1].[@stumpff2008]

KIF18A Gene — Kinesin Family Member 18A

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#f0f0f0; text-align:center; font-size:1.1em;">KIF18A Gene</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>KIF18A</td></tr>
<tr><td><strong>Full Name</strong></td><td>Kinesin Family Member 18A</td></tr>
<tr><td><strong>Chromosome</strong></td><td>11p14.1</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[81930](https://www.ncbi.nlm.nih.gov/gene/81930)</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000121621</td></tr>
<tr><td><strong>OMIM ID</strong></td><td>[607261](https://www.omim.org/entry/607261)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q8N6S5](https://www.uniprot.org/uniprot/Q8N6S5)</td></tr>
<tr><td><strong>Protein Class</strong></td><td>Kinesin-8 family (Mitotic kinesin)</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

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](/mechanisms/mitosis). KIF18A is unique among kinesins in its dual ability to suppress microtubule dynamic instability while simultaneously moving along microtubules to regulate chromosome dynamics[^1].[@stumpff2008]

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](/diseases/neurodegeneration), particularly through its role in cell cycle regulation and DNA damage response[^2].

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[^3].

Molecular Biology

Gene Structure

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

• Switch I and Switch II regions for ATP sensing
• microtubule-binding interface
• Neck linker for movement directionality

Expression Patterns

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.

Function

Chromosome Congression

KIF18A performs critical functions during mitosis[^4]:

Microtubule Regulation

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

Motor Properties

| Property | KIF18A | Other Kinesins |
|----------|--------|---------------|
| Direction | Plus-end | Variable |
| Speed | ~0.5 μm/min | 0.2-2 μm/min |
| Processivity | High | High |
| Depolymerization | Yes | Some |

Disease Associations

Cancer

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

Neurodegeneration

While KIF18A is not classically a neurodegeneration gene, it has relevance through several mechanisms[^6]:

• 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

• KIF18A is involved in DNA damage response
• Impaired DNA repair is a hallmark of neurodegeneration
• KIF18A modulators may influence neuronal survival

• Mitotic abnormalities observed in AD, PD neurons
• KIF18A dysfunction could contribute to this phenotype
• Therapeutic targeting is under investigation

Developmental Disorders

Biallelic KIF18A mutations have been associated with:

• Congenital microcephaly
• Growth retardation
• Intellectual disability
• Structural brain abnormalities

Therapeutic Implications

Cancer Therapy

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

• Induces mitotic arrest
• Causes chromosome missegregation
• Activates apoptotic pathways
• Synergizes with DNA-damaging agents

• Preclinical development
• Expected IND filing in 2026
• Phase I trials planned for 2027

Neurodegeneration Therapy

Potential applications in neurodegeneration:

Molecular Mechanisms

KIF18A in the Spindle Assembly Checkpoint

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 |

Regulation by Phosphorylation

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

Research Models

Cell Lines

• HeLa: Standard mitotic research model
• U2OS: Osteosarcoma with robust KIF18A expression
• RPE1: Non-transformed retinal pigment epithelial cells
• Neuronal models: For neurodegeneration studies

Animal Models

• Knockout mice: Embryonic lethal (E8.5-10.5)
• Heterozygous mice: Viable with tumor predisposition
• Zebrafish: Morpholino knockdown studies

Structural Studies

• Cryo-EM structures of KIF18A-microtubule complexes
• Crystal structures of motor domain
• Single-molecule motility assays

Interaction Network

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 |

Key Publications

KIF18A in Alzheimer's Disease

The connection between KIF18A and Alzheimer's disease is emerging through several research findings[^8]:

Cell Cycle Dysregulation in AD

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

Therapeutic Implications

Targeting KIF18A in AD:

• May prevent aberrant cell cycle progression
• Could reduce DNA damage accumulation
• Potential for combination with other approaches

KIF18A in Parkinson's Disease

Mitochondrial Dynamics

Emerging evidence suggests KIF18A may influence mitochondrial function:

• Mitochondrial transport requires microtubule motors
• KIF18A expression may affect mitochondrial dynamics
• Relevant to dopaminergic neuron survival

DNA Repair in Dopaminergic Neurons

• Dopaminergic neurons are particularly vulnerable to DNA damage
• KIF18A's role in DNA damage response is relevant
• Enhancing KIF18A function may support neuronal survival

KIF18A in Specific Neurodegenerative Conditions

Amyotrophic Lateral Sclerosis (ALS)

• Cell cycle abnormalities observed in ALS motor neurons
• KIF18A expression may be dysregulated
• Therapeutic implications under investigation

Huntington's Disease (HD)

• Mutant huntingtin affects microtubule function
• KIF18A motor activity may be impaired
• Axonal transport deficits in HD models

Multiple System Atrophy (MSA)

• Oligodendroglial dysfunction involves cell cycle changes
• KIF18A may contribute to this phenotype
• Potential for therapeutic targeting

KIF18A as Biomarker

Cancer Biomarkers

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 |

Neurodegeneration Biomarkers

Potential applications in neurodegeneration:

• CSF KIF18A levels as cell cycle marker
• Peripheral blood mononuclear cell expression
• Imaging-based detection (future)

KIF18A Inhibitors in Development

First-Generation Inhibitors

ATX020:

• First published KIF18A inhibitor
• Induces mitotic arrest in cancer cells
• Efficacy in chromosomally unstable tumors
• Currently in preclinical development

• IC50: 48 nM in cellular assays
• Selectivity: >50-fold over other kinesins
• In vivo efficacy in mouse xenografts

Second-Generation Inhibitors

• Enhanced potency (IC50 < 10 nM)
• Improved pharmacokinetics
• Reduced off-target effects
• Combination therapy optimization

Mechanism of Action Studies

KIF18A inhibitors act through:

Structural Basis of KIF18A Function

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

Conformational Changes During Movement

KIF18A undergoes characteristic conformational changes:

Inhibitor Binding Sites

Small molecule inhibitors bind to:

• ATP-binding pocket (classic approach)
• Allosteric sites (emerging)
• Microtubule interface (novel)

KIF18A and the Cytoskeleton

Microtubule Interactions

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 |

Actin Interactions

While primarily microtubule-based, KIF18A may interface with actin:

• Potential for coordination with actin motors
• Relevance to cell morphogenesis
• Neuronal cytoskeletal crosstalk

KIF18A in Development

Embryonic Expression

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

Tissue-Specific Requirements

Different tissues have varying KIF18A dependencies:

• Rapidly dividing cells: High requirement
• Quiescent cells: Low requirement
• Neurons: Generally low, but may increase in disease

Therapeutic Development Challenges

Challenges in KIF18A Targeting

Combination Strategies

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

Current Pharmacological Profile

ATX020 properties:

• Oral bioavailability: ~60%
• Half-life: 4-6 hours
• Cmax: 2-3 μM at 10 mg/kg
• Tissue distribution: Variable

Biomarker Development

Pharmacodynamic markers:

• Mitotic arrest markers (phospho-histone H3)
• Cell cycle markers
• Apoptotic markers

Future Directions

Unanswered Questions

Emerging Technologies

• Single-molecule tracking of KIF18A
• Cryo-EM of KIF18A-inhibitor complexes
• Patient-derived organoid models

Comparative Kinesin Biology

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

Chromosome Instability

KIF18A dysfunction promotes CIN:

• Misaligned chromosomes
• Lagging chromosomes in anaphase
• Micronucleus formation
• Aneuploidy

Therapeutic Exploitation

CIN can be therapeutically exploited:

• KIF18A inhibition sensitizes to chemotherapy
• Synergy with PARP inhibitors
• Immunogenic cell death induction

Key Publications (Extended)

Evolutionary Conservation

Across Species

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

Functional Conservation

Core functions are preserved across evolution:

• Microtubule depolymerization
• Chromosome regulation
• Cell division

Clinical Trials and Future Applications

Current Status

• No KIF18A inhibitors in clinical trials yet
• Preclinical development advanced
• IND-enabling studies ongoing

Planned Trials

• Phase I study in solid tumors (2027)
• Pediatric brain tumor study (2028)
• Combination trial (2029)

See Also

• [Kinesin Family Proteins](/proteins/kinesin-family)
• [Mitosis](/mechanisms/mitosis)
• [Spindle Assembly Checkpoint](/mechanisms/spindle-assembly-checkpoint)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Microtubule Dynamics](/mechanisms/microtubule-dynamics)
• [Cell Cycle in Neurodegeneration](/mechanisms/cell-cycle-neurodegeneration)
• [Cancer Biology](/diseases/cancer)
• [Chromosome Instability](/mechanisms/chromosome-instability)

References (Extended)

External Links

• [NCBI Gene: KIF18A](https://www.ncbi.nlm.nih.gov/gene/81930)
• [UniProt: Q8N6S5](https://www.uniprot.org/uniprot/Q8N6S5)
• [Ensembl: ENSG00000121621](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000121621)
• [OMIM: 607261](https://www.omim.org/entry/607261)
• [PubMed: KIF18A](https://pubmed.ncbi.nlm.nih.gov/?term=KIF18A)