sphingolipiden

Sphingolipiden, also known as sphingolipids, are a class of lipids characterized by a ceramide backbone formed by an amide linkage between a fatty acid and a long-chain base, typically sphingosine. They are essential components of cellular membranes and also participate in various signaling pathways.

Major subclasses include ceramides, sphingomyelins, and glycosphingolipids. Ceramides consist of sphingosine linked to a fatty acid and serve as precursors for other sphingolipids. Sphingomyelins are sphingophospholipids that contain a phosphocholine or phosphoethanolamine head group and are abundant in myelin. Glycosphingolipids include cerebrosides, globosides, and gangliosides, which bear one or more sugar residues; gangliosides are particularly enriched in neural tissue and carry sialic acid.

Biosynthesis and turnover: de novo synthesis occurs in the endoplasmic reticulum, starting from serine and palmitoyl-CoA via serine palmitoyltransferase, progressing to ceramide, which is then transported to the Golgi to form sphingomyelin and glycosphingolipids. Catabolism mainly takes place in lysosomes; sphingomyelinase and ceramidase cleave complex sphingolipids to release fatty acids, sphingosine, and other components, enabling recycling or further signaling-related processing.

Functions: sphingolipids contribute to membrane structure and the formation of lipid rafts, which organize signaling molecules. Bioactive metabolites such as ceramide and sphingosine-1-phosphate regulate processes including apoptosis, cell growth, differentiation, and vascular function, linking membrane biology to cellular signaling.

Clinical relevance: defects in sphingolipid metabolism cause lysosomal storage disorders such as Gaucher disease (glucocerebroside), Niemann-Pick disease (sphingomyelin), and Tay-Sachs disease (GM2 ganglioside). Sphingolipid signaling is also involved in neurodegenerative diseases and cancer, and therapies targeting sphingosine-1-phosphate receptors are used in multiple sclerosis.