Studies on the binding and degradation of human very-low-density lipoproteins by human hepatoma cell line HepG2

摘要: The regulation of the hepatic catabolism normal human very-low-density lipoproteins (VLDL) was studied in human-derived hepatoma cell line HepG2. Concentration-dependent binding, uptake and degradation 125I-labeled VLDL demonstrated that removal these particles proceeds through both saturable non-saturable processes. In presence excess unlabeled VLDL, specific binding 125-labeled accounted for 72% total binding. preincubation cells with had little effect on expression receptors, but reductive methylation reduced their capacity. Chloroquine colchicine inhibited increased accumulation cell, indicating involvement lysosomes microtubuli this process. Receptor-mediated associated a slight (13%) reduction de novo sterol synthesis no significant cellular cholesterol esterification. Competition studies ability low-density (LDL) high-density (HDL) to effectively compete cells. No correlation observed between concentrations apolipoproteins A-I, A-II, C-I, C-II C-III inhibitory When LDL HDL were added at equal contents either apolipoprotein B or E, only correlated E. Under similar conditions, direct function B. These results demonstrate HepG2 cells, E is main recognition signal receptor-mediated particles, while functions as sole LDL. Furthermore, lack any substantial β-hydroxy-β-methylglutaryl-CoA reductase acyl-CoA: acyltransf erase activities subsequent degradation, contrast catabolism, suggests that, processes independent those involved catabolism.