Differential effects of oxidized LDL on apolipoprotein AI and B synthesis in HepG2 cells

-Faculté de Médecine, Université de Bourgogne, 21079 Dijon, France.
Free Radical Biology and Medicine (Impact Factor: 5.74). 10/2006; 41(5):786-96. DOI: 10.1016/j.freeradbiomed.2006.05.028
Source: PubMed


Oxidized low-density lipoproteins (Ox-LDL) are key elements in atherogenesis. Apolipoprotein AI (apoAI) is an active component of the antiatherogenic high-density lipoproteins (HDL). In contrast, plasma apolipoprotein B (apoB), the main component of LDL, is highly correlated with coronary risk. Our results, obtained in HepG2 cells, show that Ox-LDL, unlike native LDL, leads to opposite effects on apoB and apoAI, namely a decrease in apoAI and an increase in apoB secretion as evaluated by [(3)H]leucine incorporation and specific immunoprecipitation. Parallel pulse-chase studies show that Ox-LDL impaired apoB degradation, whereas apoAI degradation was increased and mRNA levels were decreased. We also found that enhanced lipid biosynthesis of both triglycerides and cholesterol esters was involved in the Ox-LDL-induced increase in apoB secretion. Our data suggest that the increase in apoB and decrease in apoAI secretion may in part contribute to the known atherogenicity of Ox-LDL through an elevated LDL/HDL ratio, a strong predictor of coronary risk in patients.

  • Source
    • "These effects were partially reversed by the antioxidant caffeic acid (Fig. 1). Although enhanced apoprotein secretion by macrophages or hepatocytes in response to oxidative stress has already been reported [26] [27], the present results constitute the first report of oxidative stress effect on adipocytes from human origin. Mazzone et al. have published an important study on apoE synthesis by adipose tissue [24] [25] but only very recently, they have shown that oxidative stress downregulated apoE expression in adipocytes from murine origin [28]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Oxidative stress in adipose tissue constitutes a pathological process involved in obesity-linked metabolic disorders. Apolipoprotein E (apoE), which exhibits antioxidant properties in plasma and brain, is highly produced by adipose tissue and adipocytes. In this study, we investigated the role of apoE in the human adipocyte response to oxidative stress. We first demonstrated that apoE secretion by adipocytes was stimulated by oxidative stress. We also observed that apoE overexpression protected adipocytes from hydrogen peroxide-induced damages, by mitigating intracellular oxidation and exerting extracellular antioxidant properties. Our findings clearly show a novel antioxidant role for apoE in adipose tissue.
    Full-text · Article · Jun 2009 · FEBS letters
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper proposes a block based watermarking scheme where the information is associated to watermark blocks positions in a host image. Considering a digital image of size N×M there are many possibilities (given by the combination expression) as how to combine a given number of watermarks. For each of these possibilities, it can be assigned a bit string, making use of a coding scheme. The detector searches in the image for k positions that present the highest correlation to watermark blocks, determining where in the image these blocks were embedded. The decoding process relates these positions to a bit string. Also evaluate this technique regarding perceptual impact and show that for the same number of inserted bits use less energy if compared with other watermarking methods.
    No preview · Conference Paper · Oct 2003
  • [Show abstract] [Hide abstract]
    ABSTRACT: Obesity is characterized by ‘low grade’ and chronic inflammation, which leads to pathologies such as insulin resistance, type 2 diabetes or atherosclerosis. The role of the adipose tissue, and specifically adipocytes, in this process is discussed. Besides, the palmitoylethanolamide (PEA), an endocannabinoid-like molecule, was revealed to have an overall anti-inflammatory effect; moreover, it is secreted by adipose tissue. Thus, this review aims to understand the role of PEA in adipocytes in the case of obesity-related inflammatory states.
    No preview · Article · Dec 2010 · Drug Discovery Today Disease Mechanisms
Show more