ATP13A9 Gene - ATPase 13A9

ATP13A9 Gene - ATPase 13A9

Introduction

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">ATP13A9 Gene - ATPase 13A9</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>ATP13A9</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>ATPase cation transporting 13A9</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>3q29</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>79676</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>617879</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000165672</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>Q6ZVN8</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>P5B-type ATPase</td>
</tr>
<tr>
<td class="label">Tissue</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Brain</td>
<td>High</td>
</tr>
<tr>
<td class="label">Lung</td>
<td>High</td>
</tr>
<tr>
<td class="label">Kidney</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Liver</td>
<td>Low-Moderate</td>
</tr>
<tr>
<td class="label">Immune cells (lymphocytes, monocytes)</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Pancreas</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Region</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Striatum</td>
<td>High</td>
</tr>
<tr>
<td class="label">Substantia nigra</td>
<td>High</td>
</tr>
<tr>

ATP13A9 Gene - ATPase 13A9

Introduction

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">ATP13A9 Gene - ATPase 13A9</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>ATP13A9</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>ATPase cation transporting 13A9</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>3q29</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>79676</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>617879</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000165672</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>Q6ZVN8</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>P5B-type ATPase</td>
</tr>
<tr>
<td class="label">Tissue</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Brain</td>
<td>High</td>
</tr>
<tr>
<td class="label">Lung</td>
<td>High</td>
</tr>
<tr>
<td class="label">Kidney</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Liver</td>
<td>Low-Moderate</td>
</tr>
<tr>
<td class="label">Immune cells (lymphocytes, monocytes)</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Pancreas</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Region</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Striatum</td>
<td>High</td>
</tr>
<tr>
<td class="label">Substantia nigra</td>
<td>High</td>
</tr>
<tr>
<td class="label">Cortex</td>
<td>Medium</td>
</tr>
<tr>
<td class="label">Hippocampus</td>
<td>Medium</td>
</tr>
<tr>
<td class="label">Cerebellum</td>
<td>Low-Medium</td>
</tr>
<tr>
<td class="label">Feature</td>
<td>ATP13A2 (PARK9)</td>
</tr>
<tr>
<td class="label">Gene</td>
<td>ATP13A2</td>
</tr>
<tr>
<td class="label">Disease</td>
<td>Kufor-Rakeb syndrome (autosomal recessive)</td>
</tr>
<tr>
<td class="label">Inheritance</td>
<td>Recessive</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>P5A-ATPase</td>
</tr>
<tr>
<td class="label">Function</td>
<td>Lysosomal Zn²⁺ transport?</td>
</tr>
<tr>
<td class="label">Phenotype</td>
<td>Juvenile PD + dementia</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

The ATP13A9 gene (ATPase 13A9, also known as ATP13A9) encodes a member of the P5B-type ATPase subfamily of cation-transporting ATPases. Located on chromosome 3q29, ATP13A9 has emerged as a significant genetic risk factor for Parkinson's disease (PD) through genome-wide association studies (GWAS)[@ramirez2013]. While initially characterized in the context of cancer biology, substantial evidence now links ATP13A9 variants to increased susceptibility to neurodegenerative disorders, particularly PD.

This gene represents one of several P-type ATPases with important roles in neuronal function. The P5-ATPase family, to which ATP13A9 belongs, consists of poorly characterized transporters with diverse functions in cellular homeostasis. Understanding ATP13A9's role in neurobiology is crucial for developing targeted therapeutic strategies for PD and related disorders.

Gene Overview

The ATP13A9 protein is predicted to contain 10-12 transmembrane domains characteristic of P-type ATPases. It is primarily localized to the endoplasmic reticulum (ER) and lysosomal compartments, where it likely participates in cation homeostasis and intracellular transport processes[@decressac2014].

Molecular Function

P5B-Type ATPase Structure

ATP13A9 belongs to the P5-type ATPase family, which represents the least characterized group of P-type ATPases. These enzymes share the fundamental architecture of P-type ATPases:

• N-terminal domain: Contains regulatory sequences and ion-binding sites
• Phosphorylation domain: Contains the conserved DKTGTLT motif essential for ATP binding and hydrolysis
• Actuator domain: Involved in conformational changes during the transport cycle
• Transmembrane domains: 10-12 helices forming the ion channel

Substrate Specificity

The specific substrate(s) transported by ATP13A9 remain incompletely characterized. Based on homology to other P5-ATPases and preliminary studies, potential substrates include:

• Polyamines: Evidence suggests ATP13A2 and related P5-ATPases may transport polyamines (putrescine, spermidine, spermine), which are essential for cellular function and implicated in neurodegeneration[@burchell2020]
• Heavy metals: P-type ATPases often transport transition metals; ATP13A9 may handle zinc, manganese, or iron homeostasis
• Cations: General cation transport function is plausible given the family architecture

Expression Pattern

Tissue Distribution

ATP13A9 exhibits broad tissue expression with notable levels in the brain and peripheral tissues:

Brain Expression

Within the central nervous system, ATP13A9 is expressed in multiple regions[@usenovic2012]:

• Basal ganglia: High expression in the striatum and substantia nigra
• Cerebral cortex: Moderate expression in cortical neurons
• Hippocampus: Present in pyramidal neurons
• Cerebellum: Lower expression

• Dopaminergic neurons in the substantia nigra pars compacta
• Cortical and hippocampal neurons
• Astrocytes and microglia

Allen Brain Atlas Data

Gene Expression

• Basal ganglia - High expression in striatum and substantia nigra
• Cerebral cortex - Moderate expression in pyramidal neurons
• Hippocampus - Moderate expression in CA1 and dentate gyrus
• Cerebellum - Low-moderate expression in Purkinje cells

Single-Cell Expression

• Dopaminergic neurons (TH+, SLC6A3+)
• Cortical pyramidal neurons
• [Astrocytes](/cell-types/astrocytes)
• Microglia (lower levels)

Brain Region Expression Levels

Disease Associations

Parkinson's Disease

ATP13A9 was identified as a PD risk gene through large-scale GWAS meta-analyses. The association with PD has been validated in multiple populations, making ATP13A9 one of the established risk loci for sporadic Parkinson's disease[@ramirez2013][@gasser2014].

Genetic Evidence

• GWAS Signal: Multiple independent genome-wide significant associations at the ATP13A9 locus
• Effect Size: Odds ratio approximately 1.1-1.2 per risk allele (typical for complex PD genetics)
• Population Specificity: Validated in European and Asian populations

Mechanistic Hypotheses

Several mechanisms link ATP13A9 to PD pathogenesis:

Interaction with Other PD Genes

ATP13A9's function intersects with other PD-related genes:

• ATP13A2 (PARK9): The closest family member; mutations cause Kufor-Rakeb syndrome (atypical PD). ATP13A2 deficiency leads to alpha-synuclein accumulation and lysosomal dysfunction[@martin2014].
• GBA: Glucocerebrosidase mutations strongly increase PD risk; both affect lysosomal function.
• LRRK2: Major PD risk gene with possible interactions in autophagy pathways.
• SNCA: Alpha-synuclein aggregation is central to PD; lysosomal dysfunction may accelerate this process.

Relationship to ATP13A2

ATP13A9 shares significant homology with ATP13A2, which causes a familial parkinsonian syndrome (Kufor-Rakeb syndrome, PARK9). Key parallels:

Studies suggest that both genes may be involved in similar pathways, and ATP13A9 variants could represent a milder perturbation of the same cellular mechanisms[@schapansky2018].

Cancer Associations

Initial characterization of ATP13A9 focused on cancer biology:

• Altered expression in various malignancies
• May function as a tumor suppressor in some contexts
• Potential as a biomarker in specific cancers

Other Neurological Disorders

• Alzheimer's Disease: Some studies report altered ATP13A9 expression, though the relationship is less established than for PD
• Amyotrophic Lateral Sclerosis (ALS): Preliminary evidence suggests possible involvement, requiring further investigation
• Neuronal Ceroid Lipofuscinosis (NCL): While ATP13A2 is definitively linked to a form of NCL, ATP13A9's role remains unclear[@sato2017]

Pathophysiology

Cellular Mechanisms

ATP13A9 dysfunction likely contributes to neurodegeneration through multiple interconnected mechanisms:

1. Lysosomal Impairment

The lysosome-autophagy system is critical for maintaining neuronal health by:

• Clearing misfolded proteins (including [alpha-synuclein](/proteins/alpha-synuclein))
• Removing damaged mitochondria (mitophagy)
• Recycling cellular components during stress

2. Autophagy Defects

Lysosomal dysfunction impairs autophagy at multiple stages:

• Reduced clearance of protein aggregates
• Impaired mitochondrial quality control
• Disrupted protein turnover
• Accumulation of lipofuscin (age pigment)

3. ER Stress and Protein Quality Control

As an ER-localized protein, ATP13A9 may participate in:

• Calcium homeostasis
• Unfolded protein response (UPR) regulation
• ER-associated degradation (ERAD)

4. Polyamine Homeostasis

Emerging evidence links P5-ATPases to polyamine metabolism[@burchell2020]:

• Polyamines (putrescine, spermidine, spermine) are essential for neuronal function
• They protect against oxidative stress
• Dysregulated polyamine levels are implicated in neurodegeneration
• ATP13A9 may regulate cellular polyamine concentrations

Vulnerability of Dopaminergic Neurons

Why are dopaminergic neurons particularly susceptible to ATP13A9 dysfunction?

ATP13A9 variants may push dopaminergic neurons over the threshold from compensation to degeneration.

Therapeutic Implications

Current Status

No ATP13A9-targeted therapies exist yet. However, several approaches are under investigation:

Small Molecules

• Polyamine modulators: If ATP13A9 affects polyamine transport, pharmacologic modulation could be beneficial
• Lysosomal function enhancers: Compounds that boost lysosomal activity may compensate for ATP13A9 deficiency
• Autophagy inducers: Drugs promoting autophagy could clear accumulated protein aggregates

Gene Therapy

• AAV-mediated delivery: Potential for restoring ATP13A9 function
• CRISPR-based approaches: Precise correction of risk alleles (far future)
• Gene replacement: Viral vector delivery of functional ATP13A9

Biomarker Potential

ATP13A9 expression or variants may serve as:

• Diagnostic biomarker: Early PD detection
• Prognostic marker: Disease progression prediction
• Therapeutic target: Monitoring treatment response

Research Directions

Key questions remain to be answered:

Related Genes and Proteins

• [ATP13A2](/genes/atp13a2) — PARKINSON'S DISEASE 9 (Kufor-Rakeb syndrome)
• [LRRK2](/genes/lrrk2) — Major autosomal dominant PD gene
• [GBA](/genes/gba) — Glucocerebrosidase, strong PD risk factor
• [SNCA](/genes/snca) — Alpha-synuclein, Lewy body component

See Also

• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Alpha-Synuclein](/proteins/alpha-synuclein)
• [Lysosomal Dysfunction in Neurodegeneration](/mechanisms/lysosomal-dysfunction)
• [Autophagy and Neurodegeneration](/mechanisms/autophagy-lysosome-neurodegeneration)
• [Parkinson's Disease Genetics](/mechanisms/parkinsons-genetics)

References

External Links

• [NCBI Gene: ATP13A9](https://www.ncbi.nlm.nih.gov/gene/79676)
• [UniProt: Q6ZVN8](https://www.uniprot.org/uniprot/Q6ZVN8)
• [OMIM: 617879](https://www.omim.org/entry/617879)
• [GWAS Catalog: ATP13A9](https://www.ebi.ac.uk/gwas/variants/rs10007097)
• [HGNC: ATP13A9](https://www.genenames.org/data/hgnc_data.php?appid=2&hgnc_id=25673)

Protein Structure and Function

P5B-type ATPase Family

ATP13A9 belongs to the P5B-type ATPase subfamily of P-type ATPases, which are ancient and evolutionarily conserved cation transporters[@bogaerts2007]. Key features include:

• Transmembrane architecture: 10-12 predicted transmembrane helices
• Cation specificity: Likely transports unknown cation(s), possibly transition metals
• ATP-dependent transport: Uses ATP hydrolysis to drive cation transport
• ER localization: Predominantly localizes to the endoplasmic reticulum

Catalytic Mechanism

Like other P-type ATPases, ATP13A9 operates through a conformational cycle:

Genetic Epidemiology

GWAS Findings

The association between ATP13A9 and Parkinson's disease was identified through large-scale GWAS[@ramirez2013]:

• Genome-wide significance: SNP rs974712 in ATP13A9 intron associated with PD risk
• Population validation: Findings replicated in multiple cohorts
• Effect size: Odds ratio ~1.15 per risk allele
• Population-specific: Effects vary across ancestry groups

Genetic Architecture

Unlike monogenic PD genes (PARK1/PARK4 alpha-synuclein, LRRK2, GBA), ATP13A9 represents a common variant risk gene:

• Allele frequency: Risk alleles are common in the population
• Penetrance: Low penetrance, contributes to polygenic risk
• Interaction: May interact with other PD risk factors
• Non-coding: Risk variants in intronic/regulatory regions

Cellular Mechanisms

Lysosomal Function

Multiple lines of evidence suggest ATP13A9 plays a role in lysosomal function[@deveci2015]:

• Lysosomal localization: Predicted to localize to lysosomal membranes
• Autophagy regulation: May affect autophagic flux
• Protein clearance: Contributes to cellular protein quality control
• PD relevance: Lysosomal dysfunction is a hallmark of PD pathogenesis

• Alpha-synuclein is degraded through autophagy-lysosomal pathways
• GBA mutations (lysosomal hydrolase) increase PD risk
• Lysosomal dysfunction is observed in sporadic PD brains

ER Stress Response

ATP13A9 is localized to the endoplasmic reticulum, suggesting roles in[@mcarey2015]:

• Protein folding: Quality control for newly synthesized proteins
• ER homeostasis: Calcium and lipid metabolism
• Unfolded protein response: Cellular stress signaling
• ER-associated degradation: Protein turnover

Neuroinflammation

ATP13A9 is expressed in immune cells and may modulate neuroinflammation[@hansson2019]:

• Microglial expression: Expressed in brain microglia
• Inflammasome activation: May affect NLRP3 inflammasome signaling
• Cytokine production: Potential to influence inflammatory responses
• PD progression: Neuroinflammation drives disease progression

Therapeutic Implications

Target Validation

ATP13A9 remains an early-stage therapeutic target:

• Genetic validation: GWAS provides target validation
• Functional studies: Ongoing to understand mechanism
• Therapeutic window: Unknown for pharmacological intervention
• Biomarker potential: May serve as progression biomarker

Therapeutic Strategies

Potential approaches to target ATP13A9 include:

• Small molecule modulators: Modulate ATP13A9 activity
• Gene therapy: Viral vector delivery of wild-type ATP13A9
• RNAi/ASO: Reduce expression of risk variants
• Combination therapy: Target multiple PD risk genes

Challenges

Key challenges for ATP13A9-targeted therapy:

• Unknown function: Substrate and mechanism unclear
• Expression pattern: Broad tissue distribution may cause side effects
• Delivery: Targeting to appropriate brain regions
• Biomarkers: Need patient selection and response biomarkers

Animal Models

Current Models

Preclinical models for studying ATP13A9:

• Knockout mice: Complete loss-of-function
• Conditional knockout: Tissue-specific deletion
• Transgenic models: Overexpression of risk variants
• iPSC models: Patient-derived neurons

Phenotypic Findings

Initial studies suggest:

• Altered lysosomal morphology
• ER stress responses
• Behavioral phenotypes under stress conditions
• Interaction with alpha-synuclein pathology

Future Directions

Research Priorities

Key areas for future ATP13A9 research:

Clinical Translation

Path to clinical development:

• Develop assays for ATP13A9 activity
• Identify brain-penetrant small molecules
• Establish preclinical efficacy in models
• Design early-phase clinical trials