Sphingolipids in lipid microdomains and obesity.

Sphingolipids are major constituents of the plasma membrane, where they are known to form lipid microdomains with cholesterol. Lipid microdomains are thought to be important not only for cellular signal transduction but also for the absorption of extracellular lipids or nutrients. Inhibition of sphingolipid biosynthesis suggested an importance for sphingolipids in fatty acid uptake via lipid microdomains. Additionally, we recently reported that the function of lipid microdomains was dynamically regulated by the sphingomyelin synthase SMS2 on the plasma membrane and that SMS2-deficient mice exhibit resistance against high-fat diet-induced increases in body weight, glucose intolerance, and fatty liver. Now, biosynthesis or metabolism of sphingolipids is thought to be involved in obesity, diabetes, and cardiovascular diseases. In this review, I focus on the functions of sphingolipids in lipid microdomains and describe their contributions to obesity and diabetes.