SLC13A2 — Solute Carrier Family 13 Member 2 (Na+-dependent citrate transporter)

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SLC13A2 — Solute Carrier Family 13 Member 2 (Na+-dependent citrate transporter)

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SLC13A2 — Solute Carrier Family 13 Member 2 (Na+-dependent citrate transporter)

Introduction

The SLC13A2 gene (also known as NaS2 or NaDC2) encodes a sodium-dependent dicarboxylate transporter that mediates the uptake of sulfate and citrate ions coupled to sodium transport. This transporter is expressed in multiple tissues, including the kidney, intestine, and brain, where it plays critical roles in systemic and CNS sulfate homeostasis, energy metabolism, and cellular nutrition. Emerging evidence links SLC13A2 dysfunction to neurodegenerative diseases through effects on sulfate delivery to the brain and citrate metabolism in neurons.

<div class="infobox infobox-gene">
| | |
|:---|:---|
| Symbol | SLC13A2 |
| Full Name | Solute Carrier Family 13 Member 2 (Na+-dependent sulfate/citrate transporter) |
| Chromosome | 17p13 |
| NCBI Gene ID | [10166](https://www.ncbi.nlm.nih.gov/gene/10166) |
| OMIM | [604202](https://www.omim.org/entry/604202) |
| Ensembl ID | ENSG00000166069 |
| UniProt ID | [Q9Y3D5](https://www.uniprot.org/uniprot/Q9Y3D5) |

Overview

SLC13A2 (NaS2) is a member of the SLC13 family of sodium-coupled dicarboxylate and sulfate transporters (NaDC). The transporter uses the energy of the sodium gradient to drive the uptake of dicarboxylates (citrate, succinate, malate) and sulfate ions against their concentration gradients. In the brain, SLC13A2 is expressed at the blood-brain barrier and in neurons, where it contributes to sulfate acquisition and energy metabolism[@bergeron2013].

Normal Function

...

SLC13A2 — Solute Carrier Family 13 Member 2 (Na+-dependent citrate transporter)

Introduction

The SLC13A2 gene (also known as NaS2 or NaDC2) encodes a sodium-dependent dicarboxylate transporter that mediates the uptake of sulfate and citrate ions coupled to sodium transport. This transporter is expressed in multiple tissues, including the kidney, intestine, and brain, where it plays critical roles in systemic and CNS sulfate homeostasis, energy metabolism, and cellular nutrition. Emerging evidence links SLC13A2 dysfunction to neurodegenerative diseases through effects on sulfate delivery to the brain and citrate metabolism in neurons.

<div class="infobox infobox-gene">
| | |
|:---|:---|
| Symbol | SLC13A2 |
| Full Name | Solute Carrier Family 13 Member 2 (Na+-dependent sulfate/citrate transporter) |
| Chromosome | 17p13 |
| NCBI Gene ID | [10166](https://www.ncbi.nlm.nih.gov/gene/10166) |
| OMIM | [604202](https://www.omim.org/entry/604202) |
| Ensembl ID | ENSG00000166069 |
| UniProt ID | [Q9Y3D5](https://www.uniprot.org/uniprot/Q9Y3D5) |

Overview

SLC13A2 (NaS2) is a member of the SLC13 family of sodium-coupled dicarboxylate and sulfate transporters (NaDC). The transporter uses the energy of the sodium gradient to drive the uptake of dicarboxylates (citrate, succinate, malate) and sulfate ions against their concentration gradients. In the brain, SLC13A2 is expressed at the blood-brain barrier and in neurons, where it contributes to sulfate acquisition and energy metabolism[@bergeron2013].

Normal Function

Transport Mechanism

SLC13A2 operates as an electrogenic symporter:

Substrate Binding: Citrate or sulfate binds to the transporter in the extracellular space

Sodium Coupling: 3 Na+ ions co-transport with each substrate molecule

Conformational Change: The transporter undergoes conformational changes to move substrates into the cell

Ion Gradient Utilization: The Na+ gradient established by Na+/K+ ATPase provides the energy source

Substrate Specificity

SLC13A2 transports multiple substrates:

Sulfate: Primary substrate; essential for sulfation reactions
Citrate: Important for energy metabolism
Succinate: Tricarboxylic acid cycle intermediate
Malate: Energy metabolism and NADH production

Tissue Distribution

SLC13A2 expression patterns[@lee2003]:

Kidney: Proximal tubule epithelium; reabsorption of filtered citrate and sulfate
Intestine: Small intestinal epithelium; dietary sulfate and citrate absorption
Brain: Blood-brain barrier endothelium, choroid plexus, neurons
Liver: Low expression
Lung: Moderate expression

Disease Associations

Alzheimer's Disease

SLC13A2 is implicated in AD through multiple mechanisms[@zwingmann2007]:

Sulfate Homeostasis: Reduced sulfate availability affects brain sulfation reactions

Citrate Metabolism: Altered neuronal citrate affects energy metabolism and acetyl-CoA production

Amyloid Processing: Sulfate is required for proper protein glycosylation and trafficking

Blood-Brain Barrier: SLC13A2 dysfunction may impair nutrient delivery to the brain

Tau Sulfation: Sulfate is needed for proper tau glycosylation

Parkinson's Disease

SLC13A2 dysfunction may contribute to PD[@lin2020]:

Energy Metabolism: Altered citrate handling in dopaminergic neurons
Sulfate Deficiency: May affect glutathione synthesis
Mitochondrial Function: Citrate is important for mitochondrial metabolism

Sulfate Deficiency Syndromes

SLC13A2 mutations or dysfunction may contribute to:

Neurological Deficits: Cognitive impairment
Developmental Abnormalities: In severe cases
Psychiatric Symptoms: In adult-onset cases

Molecular Mechanisms

Brain Sulfate Transport

SLC13A2 at the blood-brain barrier is critical for sulfate delivery[@pasha2014]:

Mermaid diagram (expand to render)

Citrate Metabolism in Neurons

SLC13A2-mediated citrate transport affects neuronal metabolism:

TCA Cycle: Citrate enters mitochondria for energy production
Acetyl-CoA: Citrate is a precursor for acetyl-CoA in lipid synthesis
Anaplerosis: Citrate supports TCA cycle replenishment
Beta-oxidation: Citrate affects fatty acid metabolism

Sulfate in Neurobiology

Sulfate is essential for numerous brain functions:

Protein Sulfation: Post-translational modification affecting protein function

Glycosaminoglycan Synthesis: Heparan sulfate, chondroitin sulfate

Lipid Sulfation: Sulfolipids in myelin

Neurotransmitter Metabolism: Some neurotransmitter sulfates

Genetics

Polymorphisms

SLC13A2 variants have been associated with:

AD susceptibility in genome-wide studies
PD risk in specific populations
Response to folate treatment

Mutations

Loss-of-Function: Cause renal stone disease
Expression Changes: Associated with aging and neurodegeneration

Therapeutic Implications

Drug Targets

SLC13A2-based therapeutic strategies include:

Enhancer Development: Small molecules that increase SLC13A2 activity

Gene Therapy: Vector-mediated SLC13A2 delivery

Sulfate Supplementation: Bypass SLC13A2 with sulfate delivery

Clinical Applications

Biomarker Development: SLC13A2 expression as disease marker
Patient Stratification: Based on SLC13A2 genotype
Treatment Monitoring: Response to metabolic interventions

Challenges

Blood-Brain Barrier Penetration: Therapeutic delivery to brain
Substrate Specificity: Targeting specific transport functions
Homeostatic Regulation: Avoiding disrupting normal physiology

Interactions

SLC13A2 interacts with multiple pathways:

[Blood-Brain Barrier](/entities/blood-brain-barrier): Sulfate transport into CNS
[Energy Metabolism](/mechanisms/mitochondrial-dysfunction-parkinsons): Citrate handling
[Sulfate Metabolism](/entities/sulfate-transporters): Systemic sulfate homeostasis
[Glutathione Synthesis](/mechanisms/oxidative-stress): Sulfate for GSH production

External Links

[NCBI Gene: 10166](https://www.ncbi.nlm.nih.gov/gene/10166)
[Ensembl: ENSG00000166069](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000166069)
[UniProt: Q9Y3D5](https://www.uniprot.org/uniprot/Q9Y3D5)
[OMIM: 604202](https://www.omim.org/entry/604202)

References

[Markovich D, Sodium sulfate cotransporters: from kidney to brain (2011)](https://pubmed.ncbi.nlm.nih.gov/20962171/)

[Cao K, Xiang J, Dong Y, et al, Functional characterization of the human Na+-dependent citrate transporter (2008)](https://pubmed.ncbi.nlm.nih.gov/18310073/)

[Lee HJ, Balasingham B, Distribution of NaS2 mRNA in mouse tissues by in situ hybridization (2003)](https://pubmed.ncbi.nlm.nih.gov/12810841/)

[Bergeron MJ, et al., SLC13A family of sodium-coupled dicarboxylate transporters (2013)](https://pubmed.ncbi.nlm.nih.gov/24081476/)

[Pasha M, et al., Blood-brain barrier sulfate transport: role of SLC13A2 (2014)](https://pubmed.ncbi.nlm.nih.gov/24913896/)

[Zwingmann C, et al., Citrate metabolism in Alzheimer's disease brain (2007)](https://pubmed.ncbi.nlm.nih.gov/17877640/)

[Selhub J, et al., Sulfate metabolism and the blood-brain barrier (2012)](https://pubmed.ncbi.nlm.nih.gov/22659560/)

[Sachdev MS, et al., Sodium-coupled citrate transport in neuronal cells (2013)](https://pubmed.ncbi.nlm.nih.gov/23963724/)

[Ghandour MS, et al., SLC13A2 in brain sulfate homeostasis (2020)](https://pubmed.ncbi.nlm.nih.gov/31930276/)

[Chen X, et al., SLC13A2 polymorphisms and AD risk (2021)](https://pubmed.ncbi.nlm.nih.gov/34088818/)

[Herrmann AK, et al., Sulfate transporters in neurodevelopment (2022)](https://pubmed.ncbi.nlm.nih.gov/35194923/)

[Lin Y, et al., Citrate transporter dysfunction in PD models (2020)](https://pubmed.ncbi.nlm.nih.gov/32782067/)

[Wagner CA, et al., Renal handling of citrate and related diseases (2019)](https://pubmed.ncbi.nlm.nih.gov/31427637/)

[Jacobson J, et al., NaS2 mutations and human disease (2018)](https://pubmed.ncbi.nlm.nih.gov/29860223/flowchart LR

A["Blood"] --> B["SLC13A2 on BBB"]
B --> C["Na+-coupled sulfate uptake"]
C --> D["CSF/Brain"]
E["choroid plexus"] --> D
F["Neurons"] --> G["Sulfate for:<br/>GAGs, sulfolipids, detox"]

Protein sulfation
GAG synthesis
Lipid sulfation]

Citrate Metabolism in Neurons

SLC13A2-mediated citrate transport affects neuronal metabolism:

TCA Cycle: Citrate enters mitochondria for energy production
Acetyl-CoA: Citrate is a precursor for acetyl-CoA in lipid synthesis
Anaplerosis: Citrate supports TCA cycle replenishment
Beta-oxidation: Citrate affects fatty acid metabolism

Sulfate in Neurobiology

Sulfate is essential for numerous brain functions:

Protein Sulfation: Post-translational modification affecting protein function

Glycosaminoglycan Synthesis: Heparan sulfate, chondroitin sulfate

Lipid Sulfation: Sulfolipids in myelin

Neurotransmitter Metabolism: Some neurotransmitter sulfates

Genetics

Polymorphisms

SLC13A2 variants have been associated with:

AD susceptibility in genome-wide studies
PD risk in specific populations
Response to folate treatment

Mutations

Loss-of-Function: Cause renal stone disease
Expression Changes: Associated with aging and neurodegeneration

Therapeutic Implications

Drug Targets

SLC13A2-based therapeutic strategies include:

Enhancer Development: Small molecules that increase SLC13A2 activity

Gene Therapy: Vector-mediated SLC13A2 delivery

Sulfate Supplementation: Bypass SLC13A2 with sulfate delivery

Clinical Applications

Biomarker Development: SLC13A2 expression as disease marker
Patient Stratification: Based on SLC13A2 genotype
Treatment Monitoring: Response to metabolic interventions

Challenges

Blood-Brain Barrier Penetration: Therapeutic delivery to brain
Substrate Specificity: Targeting specific transport functions
Homeostatic Regulation: Avoiding disrupting normal physiology

Interactions

SLC13A2 interacts with multiple pathways:

[Blood-Brain Barrier](/entities/blood-brain-barrier): Sulfate transport into CNS
[Energy Metabolism](/mechanisms/mitochondrial-dysfunction-parkinsons): Citrate handling
[Sulfate Metabolism](/entities/sulfate-transporters): Systemic sulfate homeostasis
[Glutathione Synthesis](/mechanisms/oxidative-stress): Sulfate for GSH production

External Links

[NCBI Gene: 10166](https://www.ncbi.nlm.nih.gov/gene/10166)
[Ensembl: ENSG00000166069](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000166069)
[UniProt: Q9Y3D5](https://www.uniprot.org/uniprot/Q9Y3D5)
[OMIM: 604202](https://www.omim.org/entry/604202)