Absence of ACAT-1 Attenuates Atherosclerosis but Causes Dry Eye and Cutaneous Xanthomatosis in Mice with Congenital Hyperlipidemia

Abstract

Acyl-CoA:cholesterol acyltransferase (ACAT) catalyzes esterification of cellular cholesterol. To investigate the role of ACAT-1 in atherosclerosis, we have generated ACAT-1 null (ACAT-1؊/؊) mice. ACAT activities were present in the liver and intestine but were completely absent in adrenal, testes, ovaries, and peritoneal macrophages in our ACAT-1؊/؊ mice. The ACAT-1؊/؊ mice had decreased openings of the eyes because of atrophy of the meibomian glands, a modified form of sebaceous glands normally expressing high ACAT activities. This phenotype is similar to dry eye syndrome in humans. To determine the role of ACAT-1 in atherogenesis, we crossed the ACAT-1؊/؊ mice with mice lacking apolipoprotein (apo) E or the low density lipoprotein receptor (LDLR), hyperlipidemic models susceptible to atherosclerosis. High fat feeding resulted in extensive cutaneous xanthomatosis with loss of hair in both ACAT-1؊/؊:apo E؊/؊ and ACAT-1؊/؊:LDLR؊/؊ mice. Free cholesterol content was significantly increased in their skin. Aortic fatty streak lesion size as well as cholesteryl ester content were moderately reduced in both double mutant mice compared with their respective controls. These results indicate that the local inhibition of ACAT activity in tissue macrophages is protective against cholesteryl ester accumulation but causes cutaneous xanthomatosis in mice that lack apo E or LDLR.

Identification of Neutral Cholesterol Ester Hydrolase, a Key Enzyme Removing Cholesterol from Macrophages

“…Ten micrograms of proteins of various cellular fractions were separated on a 10% SDS-PAGE and transferred to a nitrocellulose membrane. For detection of the proteins, the membranes were incubated with either anti-murine NCEH, anti-murine HSL antiserum, monoclonal anti-mouse ACAT1 antibody (25), or anti-F4/80 antibody (AbD serotec) at a dilution of 1:100 -1,000. Specifically bound immunoglobulins were detected in a second reaction with a horseradish peroxidaselabeled IgG conjugate and visualized by enhanced chemiluminescence detection (ECL Plus, GE Healthcare) using a Kodak image system, and the intensity of immunoreactive bands were quantified by NIH-image software.…”

“…Cellular lipids were extracted using hexane/isopropyl alcohol (3:2), and cholesterol content was determined by enzymatic fluorometric microassay according to the method of Heider and Boyett (27), with minor modifications (25). The radioactivity of intracellular CE formed from […”

Scavenger Receptor Expressed by Endothelial Cells I (SREC-I) Mediates the Uptake of Acetylated Low Density Lipoproteins by Macrophages Stimulated with Lipopolysaccharide

“…Cells-Thioglycolate-elicited peritoneal macrophages (14) and mouse embryonic fibroblasts (15) were prepared as described previously. Cells were treated with varying concentrations of LPS (Escherichia coli O127:B8; Sigma) for 12 h before the experiments.…”

Selective Inhibition of Acyl-CoA:cholesterol Acyltransferase 2 Isozyme by Flavasperone and Sterigmatocystin from Aspergillus Species

“…However, in addition to having dry eye syndrome, the ACAT1 Ϫ/Ϫ mice with lacking apolipoprotein E or the low-density lipoprotein receptor, as hyperlipidemic models are susceptible to atherosclerosis, had extensive cutaneous xanthomatosis with loss of hair. Free cholesterol content was significantly increased in their skin [9]. While ACAT2-deficient (ACAT2 Ϫ/Ϫ ) mice lack cholesteryl ester synthesis in the intestine and liver, ACAT2…”