Sphingolipid


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Sphingolipid

Any lipid containing the long-chain amino alcohol sphingosine (structure 1 ) or a variation of it, such as dihydrosphingosine, phytosphingosine (structure 2 ),

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(1)
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(2)
or dehydrophytosphingosine. Sphingosine itself is synthesized by condensing a long-chain fatty acid with the amino acid serine.

Sphingosine is converted into a variety of derivatives to form the family of sphingolipids. The simplest form is a ceramide which contains a sphingosine and a fatty acid residue joined by an amide linkage. Ceramide is the basic building block of practically all of the naturally occurring sphingolipids. It can be further modified by the addition of a phosphorylcholine at the primary alcohol group to form sphingomyelin, a ubiquitous phospholipid in the plasma membranes of virtually all cells. Modification of a ceramide by addition of one or more sugars at the primary alcohol group converts it to a glycosphingolipid, which occurs widely in both the plant and animal kingdoms. See Glycoside, Lipid

Sphingolipids participate in diverse cellular functions. A number of inheritable diseases that can cause severe mental retardation and early death occur as the result of a deficiency in one or more of the degradative enzymes, resulting in the accumulation of a particular sphingolipid in tissues. These diseases are collectively called sphingolipidoses and include Niemann-Pick disease, Gaucher disease, Krabbe disease, metachromatic leukodystrophy, and several forms of gangliosidoses, such as Tay-Sachs disease. Functionally, glycosphingolipids are known to serve as important cell-surface molecules for mediating cell-to-cell recognition, interaction, and adhesion. They also serve as receptors for a variety of bacterial and viral toxins. Many glycosphingolipids can modulate immune responses as well as the function of hormones and growth factors by transmitting signals from the exterior to the interior of the cell. A number of glycolipids are also found to participate in a variety of immunological disorders by serving as autoantigens. Other sphingolipids and their metabolites may serve as second messengers in several signaling pathways that are important to cell survival or programmed cell death (apoptosis). See Autoimmunity

Sphingolipid

 

a complex lipid whose chemical composition includes the unsaturated amino alcohol sphingosine and the homologues or analogues of sphingosine. In all natural sphingolipids, the amino group of the sphingosine base is joined through an amide linkage to one of the higher fatty acids or hydroxy acids, which differ from one another in the length of the carbon chain and the degree of unsaturation.

Sphingolipids are divided into two main groups. The first group, the sphingophospholipids, contains residues of phosphoric acid and choline (sphingomyelins) or of phosphoric acid and inositol glycoside (phytosphingolipids). The second group, the sphingoglycolipids, contains monosaccharides, usually galactose, or oligosaccharides (cerebrosides); this group may also contain both oligosaccharides and residues of sialic acids (gangliosides).

Sphingolipids are found in the membranes of animal and plant cells. They are the main constituent of the myelin sheath of medullated nerves and of the lipids occurring in the brain. They are almost nonexistent in fat deposits. The sphingomyelins are the most widespread and constitute 20 percent of all lipids occurring in the brain. These sphingolipids consist mainly of saturated (lignoceric, stearic) acids and unsaturated acids, such as nervonic acid, having only one double bond.

REFERENCES

Zhukova, I. G., and G. P. Smirnova. “Glikolipidy.” In Uspekhi biologicheskoi khimii, vol. 9. Moscow, 1968.
Lehninger, A. Biokhimiia. Moscow, 1974. (Translated from English.)
Michalec, C. Biochemistry of Sphingolipids. Prague, 1967.

N. S. KOBRINA

sphingolipid

[¦sfiŋ·gō′lip·əd]
(biochemistry)
Any lipid, such as a sphingomyelin, that yields sphingosine or one of its derivatives as a product of hydrolysis.
References in periodicals archive ?
Arzt et al., "The sphingolipid receptor S1PR2 is a receptor for Nogo-a repressing synaptic plasticity," PLoS Biology, vol.
Lefer, "Sphingolipid therapy in myocardial ischemia-reperfusion injury," Biochimica et Biophysica Acta (BBA)--General Subjects, vol.
Schuchman, "Deregulation of sphingolipid metabolism in Alzheimer's disease," Neurobiology of Aging, vol.
Clearly, as gangliosides are mainly distributed in the lipid rafts of cell plasma membranes, which are rich in key tyrosine kinase receptors, the present study further corroborates the notion that we are at the beginning of fully unveiling the role of these sphingolipids in stem cell biology.
The first step of metabolic pathway of sphingosine1-phospate is hydrolysis in sphingomyeline by sphingomyelinases in turn generating ceramide, a proapoptotic sphingolipid in the cells (Hofmann et al., 2000).
The genes involved in sphingolipid synthesis and ketone body utilization appeared to form two nearly independent clusters with sparse interaction with the rest of the network; ASAHL (NAAA), LASS2, and UGCG did not interact with any other gene at all.
Besides these well-known risk factors, glycerophospholipids and sphingolipids which are mainly associated with lipoprotein particles contribute to atherogenesis and thus account for the elevated risk of CAD [12, 13].
The essential role of vitamin K in the synthesis of sphingolipids in the brain has been known for more than 40 years [39].
It is well known that TNF-a increases ceramides production via SMase that hydrolyses sphingomyelin, the most abundant sphingolipid specie in cell membranes [5].
For sensitivity assays with externally added sphingolipid metabolic intermediates, serial dilutions of the cells were treated in synthetic liquid medium with the indicated doses of the compounds from DMSO stock solutions and then plated onto YPD agar plates.
From the metabonomics analysis, the serum potential biomarkers of QGQS granule on SHR should be mainly focused on the metabolism of glycerophospholipid, sphingolipid, and arachidonic acid.
Results: We successfully established an orthogonal partial least squares discriminated analysis model (R[sub]2X = 71.2%, R[sub]2Y = 79.6%, and Q[sub]2 = 55.9%) and screened out 24 ions; the sphingolipid metabolism pathway showed the most drastic change.