The degradation of apolipoprotein B100: multiple opportunities to regulate VLDL triglyceride production by different proteolytic pathways

EA Fisher - Biochimica et Biophysica Acta (BBA)-Molecular and …, 2012 - Elsevier
Biochimica et Biophysica Acta (BBA)-Molecular and Cell Biology of Lipids, 2012Elsevier
Very low density lipoproteins (VLDL) are a major secretory product of the liver. They serve to
transport endogenously synthesized lipids, mainly triglycerides (but also some cholesterol
and cholesteryl esters) to peripheral tissues. VLDL is also the precursor of LDL. ApoB100 is
absolutely required for VLDL assembly and secretion. The amount of VLDL triglycerides
secreted by the liver depends on the amount loaded onto each lipoprotein particle, as well
as the number of particles. Each VLDL has one apoB100 molecule, making apoB100 …
Very low density lipoproteins (VLDL) are a major secretory product of the liver. They serve to transport endogenously synthesized lipids, mainly triglycerides (but also some cholesterol and cholesteryl esters) to peripheral tissues. VLDL is also the precursor of LDL. ApoB100 is absolutely required for VLDL assembly and secretion. The amount of VLDL triglycerides secreted by the liver depends on the amount loaded onto each lipoprotein particle, as well as the number of particles. Each VLDL has one apoB100 molecule, making apoB100 availability a key determinant of the number of VLDL particles, and hence, triglycerides, that can be secreted by hepatic cells. Surprisingly, the pool of apoB100 in the liver is typically regulated not by its level of synthesis, which is relatively constant, but by its level of degradation. It is now recognized that there are multiple opportunities for the hepatic cell to intercept apoB100 molecules and to direct them to distinct degradative processes. This mini-review will summarize progress in understanding these processes, with an emphasis on autophagy, the most recently described pathway of apoB100 degradation, and the one with possibly the most physiologic relevance to common metabolic perturbations affecting VLDL production. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.
Elsevier