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 sourceSubstrate 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 glycosylationParkinson'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)
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 sulfatesGenetics
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 deliveryClinical 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
See Also
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [SLC13A1](/genes/slc13a1)
- [SLC13A3](/genes/slc13a3)
- [Sulfate Transporters](/entities/sulfate-transporters)
- [Blood-Brain Barrier](/entities/blood-brain-barrier)
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]
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 sulfatesGenetics
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 deliveryClinical 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
See Also
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [SLC13A1](/genes/slc13a1)
- [SLC13A3](/genes/slc13a3)
- [Sulfate Transporters](/entities/sulfate-transporters)
- [Blood-Brain Barrier](/entities/blood-brain-barrier)
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/)