出版社：American Society for Biochemistry and Molecular Biology
摘要：Dietary sphingomyelin (SM) is hydrolyzed by intestinal alkalinesphingomyelinase and neutral ceramidase to sphingosine, whichis absorbed and converted to palmitic acid and acylated intochylomicron triglycerides (TGs). SM digestion is slow and isaffected by luminal factors such as bile salt, cholesterol,and other lipids. In the gut, SM and its metabolites may influenceTG hydrolysis, cholesterol absorption, lipoprotein formation,and mucosal growth. SM accounts for 20% of the phospholipidsin human plasma lipoproteins, of which two-thirds are in LDLand VLDL. It is secreted in chylomicrons and VLDL and transferredinto HDL via the ABCA1 transporter. Plasma SM increases afterperiods of large lipid loads, during suckling, and in type IIhypercholesterolemia, cholesterol-fed animals, and apolipoproteinE-deficient mice. SM is thus an important amphiphilic componentwhen plasma lipoprotein pools expand in response to large lipidloads or metabolic abnormalities. It inhibits lipoprotein lipaseand LCAT as well as the interaction of lipoproteins with receptorsand counteracts LDL oxidation. The turnover of plasma SM isgreater than can be accounted for by the turnover of LDL andHDL particles. Some SM must be degraded via receptor-mediatedcatabolism of chylomicron and VLDL remnants and by scavengerreceptor class B type I receptor-mediated transfer into cells.Supplementary key words chylomicron • very low density lipoprotein • low density lipoprotein • sphingomyelinase • ceramidase • phospholipid transfer protein
Abbreviations: apoB, apolipoprotein B; BSSL, bile salt-stimulated lipase; CE, cholesteryl ester; CETP, cholesteryl ester transfer protein; ER, endoplasmic reticulum; IDL, intermediate density lipoprotein; LRP, low density lipoprotein receptor-related protein; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PLTP, phospholipid transfer protein; SM, sphingomyelin; SMase, sphingomyelinase; SR-BI, scavenger receptor class B type I; TG, triglyceride
20% of the phospholipids in human plasma lipoproteins, of which two-thirds are in LDL and VLDL. It is secreted in chylomicrons and VLDL and transferred into HDL via the ABCA1 transporter. Plasma SM increases after periods of large lipid loads, during suckling, and in type II hypercholesterolemia, cholesterol-fed animals, and apolipoprotein E-deficient mice. SM is thus an important amphiphilic component when plasma lipoprotein pools expand in response to large lipid loads or metabolic abnormalities. It inhibits lipoprotein lipase and LCAT as well as the interaction of lipoproteins with receptors and counteracts LDL oxidation. The turnover of plasma SM is greater than can be accounted for by the turnover of LDL and HDL particles. Some SM must be degraded via receptor-mediated catabolism of chylomicron and VLDL remnants and by scavenger receptor class B type I receptor-mediated transfer into cells.
Supplementary key words chylomicron • very low density lipoprotein • low density lipoprotein • sphingomyelinase • ceramidase • phospholipid transfer protein
Abbreviations: apoB, apolipoprotein B; BSSL, bile salt-stimulated lipase; CE, cholesteryl ester; CETP, cholesteryl ester transfer protein; ER, endoplasmic reticulum; IDL, intermediate density lipoprotein; LRP, low density lipoprotein receptor-related protein; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PLTP, phospholipid transfer protein; SM, sphingomyelin; SMase, sphingomyelinase; SR-BI, scavenger receptor class B type I; TG, triglyceride
