Abstract-Mice expressing human apolipoprotein A-IV (apoA-IV) mainly in the intestine were obtained in an apolipoprotein E-deficient (apoE 0 ) background (apoA-IV/E 0 mice). Quantification of aortic lesions and plasma lipid determination showed that compared with their control apoE 0 counterparts, the apoA-IV/E 0 mice are protected against atherosclerosis without an increase in HDL cholesterol. Because oxidized lipoproteins play an important role in atherogenesis, we tested whether the protection observed in these animals is accompanied by an in vivo reduction of the oxidation parameters. The lag time in the formation of conjugated dienes during copper-mediated oxidation, the aggregation state of LDL, and the presence of anti-oxidized LDL antibodies were measured. The presence of oxidized proteins in tissues and the presence of oxidation-specific epitopes in heart sections of atherosclerotic lesions were also analyzed. Except for lag time, the results showed that the oxidation parameters were reduced in the apoA-IV/E 0 mice compared with the apoE 0 mice. This suggests that human apoA-IV acts in vivo as an antioxidant. In addition, human apoA-IV accumulation was detected in the atherosclerotic lesions of apoA-IV/E 0 mice, suggesting that apoA-IV may inhibit oxidative damage to local tissues, thus decreasing the progression of atherosclerosis. (Arterioscler Thromb Vasc

Abstract-The apolipoprotein (apo)A-I/C-III/A-IV gene cluster is involved in lipid metabolism and atherosclerosis.Overexpression of apoC-III in mice causes hypertriglyceridemia and induces atherogenesis, whereas overexpression of apoA-I or apoA-IV increases cholesterol in plasma high density lipoprotein (HDL) and protects against atherosclerosis. Each gene has been studied alone in transgenic mice but not in combination as the entire cluster. To determine which phenotype is produced by the expression of the entire gene cluster, transgenic mice were generated with a 33-kb human DNA fragment. The results showed that the transgene contained the necessary elements to direct hepatic and intestinal expression of the 3 genes. In the pooled data, plasma concentrations were 257Ϯ9, 7.1Ϯ0.5, and 1.0Ϯ0.2 mg/dL for human apoA-I, apoC-III, and apoA-IV, respectively (meanϮSEM). Concentrations of these apolipoproteins were higher in males than in females. Human apoA-I and apoC-III concentrations were positively correlated, suggesting that they are coregulated. Transgenic mice exhibited gross hypertriglyceridemia and accumulation of apoB 48 -containing triglyceride-rich lipoproteins. Plasma triglyceride and cholesterol concentrations were correlated positively with human apoC-III concentration, and HDL cholesterol was correlated with apoA-I concentration. In an apoE-deficient background, despite being markedly hypertriglyceridemic, cluster transgenic animals compared with nontransgenic animals showed a 61% reduction in atherosclerosis. This suggests that apoA-I and/or apoA-IV can protect against atherosclerosis even in the presence of severe hyperlipidemia. These mice provide a new model for studies of the regulation of the 3 human genes in combination. Key Words: transgenic mice Ⅲ hypertriglyceridemia Ⅲ cholesterol Ⅲ lipoproteins Ⅲ atherosclerosis P lasma lipoproteins influence the development of atherosclerosis, and their concentrations are associated with the risk of coronary heart disease. 1 The genes for 3 apolipoproteins, apoA-I, apoC-III, and apoA-IV, are grouped together in a cluster on 17 kb of human chromosome 11. 2 ApoA-I is the major protein component of HDL. Through its ability to promote cholesterol efflux from cultured cells and to activate lecithin:cholesterol acyltransferase (LCAT), it is involved in reverse cholesterol transport (RCT). 1 Expression of the human apoA-I ( h apoA-I) gene decreases the development of fatty lesions in cholesterol-fed transgenic (Tg) mice 3 and in apoE-deficient (apoE Ϫ/Ϫ ) mice. 4 ApoA-I deficiency in mice did not increase atherogenesis in a normal background 5 but did so in hypercholesterolemic mice expressing human apoB. 6 ApoC-III is a component of HDL and triglyceride-rich lipoproteins (TGRLs). Plasma apoC-III concentration is positively correlated with triglyceride concentration. By inhibiting TGRL catabolism, apoC-III induces hypertriglyceridemia in Tg mice. 7 Expression of the gene was not atherogenic in apoE Ϫ/Ϫ mice. 8 In contrast, h apoC-III expression, in normal or in LDL ...

The proximal promoter region of the human transferrin gene contains an hepatocyte-specific cis-element (PRI, nucleotides -76 to -51) whose DNA sequence is homologous to a sequence (nucleotides -89 to -68) present in the transcriptionally essential 5' region of the human antithrombin III gene and to another hepatocyte-specific sequence (A domain) of the human alpha 1-antitrypsin gene promoter. The results reported here lead to the conclusion that the liver trans-acting factor Tf-LF1, binding to the transferrin PRI cis-element interacts with the homologous antithrombin III region, but is different from the transcription factor LF-A1 interacting with the A domain of the alpha 1-antitrypsin promoter. The distal region DRI (nucleotides -480 to -454) of the human transferrin gene promoter presents in its core the same 10 nucleotide-long sequence as the PRI cis-element. We have previously shown that the liver protein Tf-LF2, binding to the DRI element is different from the Tf-LF1 trans-acting factor. In this paper we also show that Tf-LF2 is different from the transcription factor LF-A1 interacting with the alpha 1-antitrypsin promoter. The results allow us to conclude that at least three distinct liver nuclear proteins bind to different subsets of 5' DNA regions containing similar sequences. These sequences are present in genes expressed essentially in liver.