The effect of low density lipoproteins, cholesterol, and 25-hydroxycholesterol on apolipoprotein B gene expression in HepG2 cells.

摘要: The purpose of the present study was to examine effects exogenous cholesterol on apolipoprotein (Apo) B gene expression in HepG2 cells. Pure had no significant effect either cellular content cholesteryl esters or net accumulation neutral lipids and ApoB culture medium. By contrast, addition 25-hydroxycholesterol increased cells medium by 2-3-fold decreased that unesterified 50% both compartments. A 33% reduction triglycerides commensurate with a 40% increase their 3-fold predominantly due enhanced secretion newly synthesized as established pulse-chase studies. stimulation accompanied 55% mRNA. Under these experimental conditions, low density lipoprotein receptor activity only 12-20%. Addition progesterone prevented 25-hydroxycholesterol. changes concentration were reflected composition secreted "low-density" lipoproteins. These particles percentage contents comparison lipoproteins produced control rate production not correlated triglyceride mass but positively triglycerides. With exception unchanged mRNA levels, plasma similar, although less pronounced, ApoB. results demonstrate synthesis are tightly coupled ApoB-containing primarily stimulating rather than reducing catabolism.