The acetyl low density lipoprotein (LDL) receptor is expressed on macrophages and some endothelial cells and mediates macrophage-foam cell formation in culture. A 2Z0-kDa acetyl LDL binding protein was partially purified from bovine liver membranes and was used to make a specific monoclonal antibody. The 220-kDa protein immunoprecipitated by this antibody retained binding activity, and the antibody was used to detect this protein in cells lining bovine liver sinusoids and on the surface of cultured bovine alveolar macrophages. In the human monocytic cell line THP-1, the expression of both acetyl LDL receptor activity and a 220-kDa acetyl LDL binding protein were dramatically induced in parallel after differentiation to a macrophage-like state induced by phorbol ester. The ligand specificity, tissue and cell-type specificity, and coinduction data indicated that this 220-kDa cell-surface binding protein is probably a receptor that mediates acetyl LDL endocytosis. The 220-kDa protein, which was purified 238,000-fold from bovine lung membranes to near homogeneity using monoclonal antibody affinity chromatography, is a trimer of 77-kDa subunits that contain asparaginelinked carbohydrate chains.A hallmark of atherosclerosis is the deposition of plasma cholesterol in atherosclerotic plaques in arterial walls (1). Key cellular components of plaques are foam cells, which are derived from monocytes-macrophages (2-4). Chemically modified low density lipoprotein (LDL), such as acetyl LDL, can be rapidly taken up by cultured macrophages via receptor-mediated endocytosis resulting in foam cell formation. This suggested that the acetyl LDL receptor system may play an important role in the formation offoam cells in vivo (5-10). Acetyl LDL receptor activity has also been detected in endothelial cells but is usually not expressed at substantial levels in other cell types. This receptor activity is induced during differentiation of cultured human monocytes into macrophages (11) and by the phorbol ester-induced differentiation of the human monocytic cell line THP-1 (12). In vivo, high levels of acetyl LDL receptor activity have been detected in the liver, especially in cells lining liver sinusoids, adrenal gland, spleen, and several other organs (13-15). A ligand blotting assay of unreduced specimens has been used by Via and colleagues (16,17) to detect acetyl LDL binding proteins of 200-260 kDa in a murine macrophage cell line, P388dl, and in rat liver. To obtain further information about the acetyl LDL receptor, we purified and made a monoclonal antibody against a 220-kDa bovine liver protein that exhibited acetyl LDL binding activity. Several lines of evidence, including ligand specificity and cell-type and tissue specificity, indicate that this 220-kDa protein is probably an acetyl LDL receptor. The 220-kDa protein was purified to near homogeneity and was shown to be a trimer of 77-kDa glycoprotein subunits that contain asparagine-linked carbohydrate chains. METHODSMaterials. All reagents were obtained as described ...

Background-Adriamycin (ADR) is an anticancer drug known to cause severe cardiac toxicity by generating free radicals.We investigated the role of a redox-regulating molecule, thioredoxin-1 (TRX1), in ADR-induced cardiotoxicity. Methods and Results-The in vitro study showed that TRX1 was dose-dependently increased concomitant with the formation of hydroxyl radicals in ADR-treated neonatal rat cardiomyocytes. Lactate dehydrogenase-releasing assay showed that treatment with recombinant human TRX1 suppressed cardiomyocyte injury in ADR-treated cardiomyocytes. To examine the biological significance of TRX1 in vivo, we used transgenic mice expressing increased levels of human TRX1 (TRX1-TG mice). Electron microscopy revealed that mitochondria, myofibrils, and other cellular details were much better maintained in ADR-treated TRX1-TG mice than in ADR-treated nontransgenic (WT) mice. The increase in the protein carbonyl content, a marker of cellular protein oxidation, was suppressed in ADR-treated TRX1-TG mice compared with ADR-treated WT mice. The formation of hydroxyl radicals in ADR-treated heart homogenates of TRX1-TG mice was decreased compared with WT mice. For the survival study, all WT mice treated with ADR died within 6 weeks, but 5 of 6 TRX1-TG mice treated with ADR survived Ͼ8 weeks. Conclusions-TRX1 is upregulated by intracellular oxidative stress generated by ADR. TRX1 has a protective role against ADR-induced cardiotoxicity by reducing oxidative stress.

As oxidative stress plays a crucial role in the development and pathogenesis of hypertension, we analyzed the redox (reduction/oxidation) status in tissues from Wistar-Kyoto rats (WKY), spontaneously hypertensive rats (SHR), and stroke-prone SHR (SHRSP). Expressions of 8-hydroxy-2'-deoxyguanosine, a marker for oxidative stress-induced DNA damage, and protein carbonylation, a marker for oxidation status of proteins, were enhanced in aorta, heart, and kidney from SHR and SHRSP compared with WKY. The expression of redox regulating protein, thioredoxin (TRX), estimated by immunohistochemistry and western blot, and expression of TRX gene estimated by real-time RT-PCR were markedly suppressed in those tissues from SHR and SHRSP compared with WKY. Induction of TRX was impaired after angiotension II treatment in peripheral blood mononuclear cells isolated from SHR and SHRSP compared with those isolated from WKY. Although previous reports have shown that TRX is induced by a variety of oxidative stress in tissues, the present study shows the impaired induction of TRX in tissues from genetically hypertensive rats despite the relative increment of oxidative stress. Redox imbalance in essential organs may play a crucial role in the development and pathogenesis of hypertension.

MicroRNAs (miRNAs) are endogenous small RNAs that play an important role in various physiological processes by downregulating target genes. Recently, plasma miRNAs have been investigated as biomarkers for various diseases. In this study, miRNA array analysis in various tissues showed that miR-124 is almost exclusively expressed in the central nervous system and neuronal cells, suggesting that it might be useful as a potential biomarker for neurological diseases. We examined whether plasma concentrations of brain-specific miRNA can serve as a biomarker for cerebral infarction, where the cerebral infarction was modeled by middle cerebral artery occlusion (MCAO) in the rat. Plasma concentrations of miR-124 were significantly elevated at 6 h, and remained elevated at 48 h after MCAO introduction. Thus, plasma concentration of miR-124 provides a promising candidate biomarker for early detection of cerebral infarction.