Sphingosine-1-phosphate (S1P) is a bioactive lipid produced by sphingolipid metabolism and is involved in a variety of basic cellular functions, such as cell proliferation, migration, survival, and intercellular signaling. S1P can be produced intracellularly by sphingosine catalyzed by specific sphingosine kinase (SphK), but can also be catabolized by S1P phosphatase or S1P lyase (S1PL), thus ensuring the dynamic balance of S1P in the human physiological environment. S1P can act as a second messenger directly on intracellular targets, or can be transported extracellularly by transporter proteins to bind to the corresponding receptors (S1PR) and exert biological effects. Unlike ceramide and sphingomyelin, it stimulates cell growth and inhibits apoptosis. The three constitute an important metabolic equilibrium called the "sphingomyelin rheostat".
Metabolism of sphingosine-1-phosphate
In the presence of SphKs, sphingosine and dihydrosphingosine are phosphorylated to S1P. Antagonists of growth factor receptors (including platelet-derived growth factor, vascular endothelial growth factor, nerve growth factor, and epidermal growth factor), ligands for G protein-coupled receptors, transforming growth factor β, the proinflammatory cytokine tumor necrosis factor α, and cross-linking of immunoglobulin receptors all stimulate sphingosine kinase activation, increasing intracellular S1P concentrations and S1P release into the extracellular compartment in some cell types.
Sphingosine kinase has 2 isoforms, sphingosine kinase 1 and sphingosine kinase 2. The 2 isoforms have different cellular localizations and different biological functions. In unstimulated cells, sphingosine kinase 1 is located in the cytoplasm. When cells are stimulated, sphingosine kinase 1 is translocated to the cell membrane, cytoskeleton and organelles. The translocation of sphingosine kinase 1 to the cell membrane is an important feature of its activation. Overexpression of sphingosine kinase 1 and the corresponding increase in S1P production promotes cell growth. Sphingosine kinase 2 is present both in the cytoplasm and in the nucleus, and its localization depends on the cell type. In contrast to sphingosine kinase 1, sphingosine kinase 2 inhibits cell growth and promotes apoptosis in a non-dependent manner with S1P receptors (S1PRs).
The degradation of S1P is mediated by 2 different enzymes. S1P lyase (SPL) located in the endoplasmic reticulum irreversibly cleaves S1P in the cytoplasm to produce phosphoethanolamine and hexadecene. In addition to cleavage by S1P lyase, S1P can also be degraded by lipid phosphatase-mediated dephosphorylation.
S1P metabolism (Wang et al., 2017)
Detection of sphingosine-1-phosphate
The LC-MS/MS technology platform can be used for efficient and accurate qualitative and quantitative analysis. The advantages of LC-MS/MS technology are the ability of LC to separate a wide range of compounds and the ability of MS to quantify compounds with high sensitivity and selectivity based on a unique mass-to-charge ratio (m/z) conversion.
S1P is separated by methanol precipitation combined with ultrasonic extraction, and the supernatant is quantified by liquid-mass spectrometry in selective ion monitoring mode after high-speed centrifugation to remove large particles.
Creative Proteomics provides qualitative and quantitative analysis of sphingosine 1-phosphate for customers in the pharmaceutical, food and bioscience industries based on an LC-MS/MS technology platform.
