Investigators at the Cleveland Clinic Foundation found that cholesteryl ester transfer protein (CETP) is involved in the cellular storage and regulation of cholesterol and other fats.
“CETP is known to shuttle different types of fat between lipoproteins, combinations of fat and protein that transport fats in the blood,” says Richard E. Morton research scientist. “In this study, we show that CETP also shuttles fats inside fat cells between two separate areas and that fat cells with reduced levels of CETP are unable to process fats normally.”
The team noticed that fat cells lacking CETP could not make and store cholesterol, cholesteryl ester, and triglyceride like normal fat cells do. In these cells, cholesteryl ester and triglyceride accumulated in the endoplasmic reticulum (ER), while an abnormally low amount of these fats were seen in lipid droplets.
The scientists beleive that in normal cells, CETP transfers cholesteryl ester and triglyceride from the ER where they are made into the lipid droplets where they are stored. In CETP-deficient cells, only a fraction of both fats are carried from the ER to the lipid droplets. Also, since cholesterol is produced by breaking down cholesteryl ester in lipid droplets, lower levels of cholesteryl ester lead to smaller amounts of cholesterol in the droplets.
“CETP deficiency disrupts storage of important fats in fat cells, which can lead to insulin resistance, a major contributor to diabetes, and the abnormal release of cytokines,” Morton adds.
The new study will be published in the July 27 issue of the Journal of Biological Chemistry.