Reduced Expression of the Macrophage Scavenger Receptors in Macrophage-like Cell Mutants Resistant to Brefeldin A

Abstract Brefeldin A (BFA)-resistant mutants, JB15, JB23 and JB33, were isolated from mutagenized murine macrophage-like (J774) cells and their modified low density lipoprotein (LDL) metabolism was studied. When JB23 cells, the most resistant clone, were incubated with acetylated LDL, intracellular accumulation of cholesteryl esters (CE) was reduced by 31% as compared with J774 cells. The cell-association of 125 I-acetyl-LDL with, and subsequent endocytic degradation by JB23 cells were reduced by 40–60% compared with J774 cells. Western and Northern blot analyses showed that the protein and mRNA levels of the macrophage scavenger receptors (MSR) were reduced by 68% and 55% respectively in JB23 cells as compared with those in J774 cells. These results indicate that a putative BFA-target molecule(s) might regulate MSR gene expression as well as macrophage-derived foam cell formation.