Exogenous phospholipase C specifically inhibits apoE expression in mouse peritoneal macrophages

Treatment of cholesterol-loaded mouse peritoneal macrophages with exogenous phospholipase C results in a specific and dose-dependent inhibition of apoE secretion. The inhibition of apoE secretion is secondary to the rapid and specific inhibition of its synthesis. The profound changes in rates of apoE synthesis are not accompanied by changes in the levels of apoE mRNA, an observation strongly suggestive of translational regulation of expression. The changes in apoE expression coincide with, or are preceded by a three-fold increase in membrane-bound protein kinase C activity, pointing out the potential importance of this signal transduction pathway in regulating apoE expression at a posttranscriptional locus.