Moberly J B, Cole T G, Alpers D H, Schonfeld G
Division of Atherosclerosis, Washington University School of Medicine, St. Louis, MO.
Biochim Biophys Acta. 1990 Jan 16;1042(1):70-80. doi: 10.1016/0005-2760(90)90058-6.
HepG2 and Caco-2 cells were studied to compare the regulation of liver and intestinal apolipoprotein (apo) biosynthesis and secretion by fatty acids. Incubation with fatty acid consistently stimulated apoB production by both HepG2 and Caco-2 cells. Media concentrations of apoB, determined by radioimmunoassay, were approx. 3-fold greater for cells incubated for 24 h in serum-free medium containing oleic acid bound to albumin than for cells incubated with albumin alone. Oleic acid also resulted in a 2-3-fold accumulation of cellular triacylglycerol for HepG2 cells and Caco-2 cells. Cellular apoB and media and cellular apoA-I concentrations were not affected by oleic acid. Immunoblotting with a monoclonal antibody against human apoB confirmed a greater mass of apoB in media from HepG2 and Caco-2 cells incubated with oleic acid. Radiolabeled apoB-100 was also increased in media from HepG2 and Caco-2 cells incubated with [35S]methionine for 24 h in the presence of oleic acid, suggesting enhanced apoB synthesis. However, apoB mRNA concentrations were unchanged in response to oleic acid. Gel filtration of media by fast protein liquid chromatography (FPLC) revealed a redistribution of apoB from LDL-sized particles to VLDL or chylomicrons in media from Caco-2 cells incubated with oleic acid, whereas apoB remained in LDL for HepG2 cells. ApoA-I in media from HepG2 and Caco-2 cells eluted as free or lipid-poor apoA-I, and the apoA-I distribution was unaltered by incubation with oleic acid. These data demonstrate that HepG2 and Caco-2 cells maintained in supplemented serum-free medium respond to oleic acid by a similar post-transcriptional increase in apoB synthesis, but different packaging of apoB into triacylglycerol-rich lipoproteins.
对HepG2和Caco-2细胞进行了研究，以比较脂肪酸对肝脏和肠道载脂蛋白（apo）生物合成及分泌的调节作用。脂肪酸孵育持续刺激HepG2和Caco-2细胞产生载脂蛋白B。通过放射免疫测定法测定的载脂蛋白B培养基浓度，对于在含有与白蛋白结合的油酸的无血清培养基中孵育24小时的细胞，约为单独与白蛋白孵育的细胞的3倍。油酸还导致HepG2细胞和Caco-2细胞的细胞三酰甘油积累2 - 3倍。细胞载脂蛋白B以及培养基和细胞载脂蛋白A-I浓度不受油酸影响。用抗人载脂蛋白B单克隆抗体进行免疫印迹证实，与油酸孵育的HepG2和Caco-2细胞培养基中的载脂蛋白B质量更大。在油酸存在下，用[35S]甲硫氨酸孵育24小时的HepG2和Caco-2细胞培养基中，放射性标记的载脂蛋白B-100也增加，表明载脂蛋白B合成增强。然而，载脂蛋白B mRNA浓度对油酸无反应。通过快速蛋白质液相色谱（FPLC）对培养基进行凝胶过滤显示，与油酸孵育的Caco-2细胞培养基中的载脂蛋白B从低密度脂蛋白（LDL）大小的颗粒重新分布到极低密度脂蛋白（VLDL）或乳糜微粒，而HepG2细胞的载脂蛋白B仍保留在LDL中。HepG2和Caco-2细胞培养基中的载脂蛋白A-I以游离或低脂载脂蛋白A-I形式洗脱，并且与油酸孵育不改变载脂蛋白A-I的分布。这些数据表明，维持在补充的无血清培养基中的HepG2和Caco-2细胞通过转录后类似地增加载脂蛋白B合成来响应油酸，但将载脂蛋白B包装到富含三酰甘油的脂蛋白中的方式不同。
