Molecular cloning, sequence, and expression of cynomolgus monkey cholesteryl ester transfer protein. Inverse correlation between hepatic cholesteryl ester transfer protein mRNA levels and plasma high density lipoprotein levels.

Abstract

A cDNA clone containing the coding region for cynomolgus monkey cholesteryl ester transfer protein (CETP) was isolated by the polymerase chain reaction with primers based on the human CETP cDNA sequence and cDNA synthesized from liver poly (A+) RNA. Analysis of that cDNA indicated that the nucleotide and amino acid sequences of cynomolgus monkey CETP were greater than 95% homologous with the human sequences. A fragment of the cDNA was used to develop an internal-standard/RNAse protection assay that allowed precise quantification of CETP mRNA levels. Analysis of total RNA from various tissues with this assay revealed that the liver and thoracic aorta expressed high levels of CETP mRNA; the mesenteric fat, adrenal gland, spleen, and abdominal aorta had low but detectable levels of the mRNA; and the brain, kidney, intestine, and skeletal muscle had undetectable levels of that mRNA. When the monkeys were made hypercholesterolemic by a high-fat, high-cholesterol (HFHC) diet, hepatic levels of CETP mRNA increased from 1.6±0.4 pg//ig total RNA (mean±SEM) to 4.1 ±0.8 pg//ig (p<0.005); mesenteric fat CETP mRNA increased from 0.4±0.1 pg/ftg total RNA to 5.3±2.2 pg/ftg (p<0.05); and plasma CET activity increased approximately fourfold. The CETP mRNA levels in the thoracic and abdominal aortas were not significantly increased in monkeys fed the HFHC diet, even though those animals had gross atherosclerosis. The apoprotein E mRNA levels, however, were markedly increased in the aortas of monkeys with atherosclerosis, with the largest increase occurring in the abdominal aorta. Taken together, these data suggest that lipid deposition in the artery was not accompanied by increased expression of the CETP gene in that tissue. Statistical analysis showed that a strong, negative correlation existed between hepatic CETP mRNA levels and both high density lipoprotein cholesterol (r=-0.85, p<0.001) and apoprotein A-I (r= -0.84,p<0.001). These data suggest that HFHC diet-induced changes in high density lipoprotein metabolism may be linked to altered expression of a functional CETP gene. (Arteriosclerosis and Thrombosis 1991;11:1759-1771)

Cholesteryl Ester Transfer Protein Variants Have Differential Stability but Uniform Inhibition by Torcetrapib

“…For example, L151P was omitted from analysis because it had been shown to be inactive (12). Also shown in Table II are the common and rare alleles for human CETP and the homologous amino acids for monkey (13), rabbit (14), shrew (15), and hamster (16) CETP. Amino acids at three of the nine sites are completely conserved across other species, whereas the other six are polymorphic.…”

Cholesteryl Ester Transfer Protein Biosynthesis and Cellular Cholesterol Homeostasis Are Tightly Interconnected

“…In humans, liver, spleen, and adipose tissue are the most abundant sources of CETP mRNA (7). Studies in nonhuman primates also demonstrate that adipose tissue expresses high levels of CETP mRNA (8,9). All human tissues expressing CETP contain both a full-length form, which gives rise to plasma CETP, and a shortened mRNA, in which the exon 9-derived sequence has been deleted (10).…”

Hyperalphalipoproteinemia in human lecithin cholesterol acyltransferase transgenic rabbits. In vivo apolipoprotein A-I catabolism is delayed in a gene dose-dependent manner.

“…In general, plasma apoA-I concentrations are subject to regulation at the levels of a) synthesis, b) catabolism, and c) lipoprotein particle remodeling. Kinetic studies in both human (13)(14)(15)(16)(17) and nonhuman (18,19) primates have established that plasma apoA-I concentrations are primarily determined by the rate of apoA-I catabolism, rather than by production. However, the processes responsible for defining the life span of apoA-I-containing particles are not completely understood.…”