SPTLC2 (Serine Palmitoyltransferase Long Chain Base Subunit 2) encodes the small subunit (sPTLC2) of serine palmitoyltransferase (SPT), the rate-limiting enzyme in de novo sphingolipid biosynthesis. Located on chromosome 14q31.3, SPTLC2 forms a heterodimer with SPTLC1 to catalyze the condensation of serine and palmitoyl-CoA, producing 3-ketosphinganine—the first step in sphingolipid synthesis. Mutations in SPTLC2 cause hereditary sensory and autonomic neuropathy type 1 (HSAN1), while dysregulated sphingolipid metabolism is implicated in Alzheimer's disease, Parkinson's disease, and various neurodegenerative conditions.
| Attribute | Value |
|---|---|
| Gene Symbol | SPTLC2 |
| Full Name | Serine Palmitoyltransferase Long Chain Base Subunit 2 |
| Alternative Names | SPT2, SPT small subunit 2, LCB2 |
| Chromosomal Location | 14q31.3 |
| NCBI Gene ID | 9517 |
| Ensembl ID | ENSG00000166800 |
| UniProt ID | O15270 |
| OMIM | 610313 |
| Protein Class | Enzyme; Lipid metabolism |
| Associated Diseases | HSAN1, Alzheimer's disease, Parkinson's disease |
The SPTLC2 gene spans approximately 21 kb and consists of 12 exons encoding a 422-amino acid protein. The protein contains an N-terminal transmembrane domain and a C-terminal catalytic domain facing the cytosol.
SPTLC2 contains several functional domains[1]:
SPTLC2 is the catalytic subunit of serine palmitoyltransferase:
SPTLC2 initiates the sphingolipid biosynthesis pathway:
Palmitoyl-CoA + Serine → 3-Ketosphinganine → Sphinganine → Dihydroceramide → Ceramide
↓
Sphingosine → Sphingosine-1-phosphate
↓
Ceramide → Sphingomyelin, Glycosphingolipids
The products of SPTLC2 activity serve critical functions:
SPTLC2 is expressed in various brain regions:
Expression in both central and peripheral nervous systems explains the neuropathy phenotype in SPTLC2 mutants.
SPTLC2 activity is regulated at multiple levels:
SPTLC2 mutations cause HSAN1B (OMIM 613640)[6]:
The pathogenesis involves a toxic gain-of-function mechanism[7][8]:
The accumulation of 1-deoxysphingolipids is toxic to peripheral sensory and autonomic neurons, causing the characteristic neuropathy phenotype.
SPTLC2 dysregulation is implicated in Alzheimer's disease through multiple mechanisms[10][11]:
Elevated ceramide levels are observed in AD brain:
Amyloid-β induces sphingolipid metabolism changes:
Ceramide accumulation triggers neuronal dysfunction[9:1]:
Sphingolipid alterations affect synaptic plasticity[5:1]:
Ceramide promotes tau pathology[14]:
SPTLC2 may contribute to Parkinson's disease[15]:
Sphingolipid metabolism is altered in the substantia nigra:
Membrane lipid composition affects α-syn aggregation:
Ceramide induces mitochondrial apoptosis:
Sphingolipids modulate glial activation:
Lipid rafts are specialized membrane microdomains enriched in sphingolipids and cholesterol. In neurons, lipid rafts serve crucial functions[2:1]:
Ceramide directly affects mitochondrial function[16]:
SPTLC2 encodes the catalytic subunit of serine palmitoyltransferase, the rate-limiting enzyme in de novo sphingolipid biosynthesis. Mutations in SPTLC2 cause hereditary sensory and autonomic neuropathy type 1 (HSAN1) through toxic 1-deoxysphingolipid accumulation. Beyond this rare disease, dysregulated sphingolipid metabolism contributes to common neurodegenerative conditions including Alzheimer's and Parkinson's disease. The enzyme's role in ceramide production links it to multiple pathological processes including ER stress, mitochondrial dysfunction, synaptic loss, and neuroinflammation. Therapeutic targeting of SPTLC2 and downstream sphingolipid pathways holds promise for treating both rare and common neurodegenerative disorders.
SPTLC2 is a potential therapeutic target for multiple conditions:
| Approach | Target | Status |
|---|---|---|
| Serine supplementation | Reduce 1-deoxysphingolipid production | Clinical trials[17] |
| SPT inhibitors | Reduce toxic lipid production | Preclinical |
| Ceramide modulators | Target downstream effects | Discovery |
| Gene therapy | Restore normal SPT function | Research |
High-dose L-serine has shown promise in HSAN1[17:1]:
Targeting ceramide metabolism in neurodegeneration:
Yardeni T, et al. Crystal structure of serine palmitoyltransferase. Nat Struct Mol Biol. 2011. ↩︎
Simons K, et al. Lipid rafts and neurodegeneration. Nat Rev Neurosci. 2012. ↩︎ ↩︎
Hait NC, et al. Sphingosine-1-phosphate in neuroprotection. Nat Rev Neurosci. 2014. ↩︎
Chrast R, et al. Sphingolipids in myelin formation and maintenance. Glia. 2011. ↩︎
Svennerholm L, et al. Sphingolipids in synaptic function. J Neurochem. 2015. ↩︎ ↩︎
Rotthier A, et al. Mutations in SPTLC2 cause hereditary sensory neuropathy type 1. Brain. 2010. ↩︎
Bode H, et al. 1-deoxysphingolipids cause HSAN1 pathology. Brain. 2016. ↩︎
Eichler F, et al. SPT accepts alanine as substrate in HSAN1. J Biol Chem. 2009. ↩︎
Kim HJ, et al. Ceramide triggers ER stress in neurons. Cell Death Dis. 2019. ↩︎ ↩︎
Couture R, et al. Sphingolipid metabolism in Alzheimer's disease. Prog Lipid Res. 2019. ↩︎
Liu Y, et al. Ceramide accumulation in Alzheimer's disease brain. J Neurosci. 2018. ↩︎
Grange J, et al. Amyloid-beta induces ceramide synthesis. Cell Mol Neurobiol. 2014. ↩︎
Siddique MM, et al. Ceramide-induced neuronal apoptosis. Cell Death Differ. 2019. ↩︎
He X, et al. Ceramide promotes tau phosphorylation. Neurobiol Aging. 2020. ↩︎
Taguchi Y, et al. Ceramide in Parkinson's disease models. Mov Disord. 2017. ↩︎
Diófano A, et al. Ceramide regulates mitophagy in neurodegeneration. Autophagy. 2021. ↩︎
Cruccu A, et al. Serine supplementation therapy for HSAN1. Neurology. 2020. ↩︎ ↩︎