Levy E, Yotov W, Seidman E G, Garofalo C, Delvin E, Ménard D
Centre de Recherche, Hôpital Sainte-Justine, Université de Montréal, Montréal, Quebec H3T 1C5, Canada.
Biochim Biophys Acta. 1999 Aug 18;1439(3):353-62. doi: 10.1016/s1388-1981(99)00085-2.
Caco-2 cells and human colonic explants were compared for their ability to esterify lipid classes, synthesize apolipoproteins and assemble lipoproteins. Highly differentiated cells and colonic explants were incubated with [(14)C]oleic acid or [(35)S]methionine for 48 h. Caco-2 cells demonstrated a higher ability to incorporate [(14)C]oleic acid into cellular phospholipids (13-fold, P<0.005), triglycerides (28-fold, P<0.005) and cholesteryl ester (2-fold, P<0. 01). However, their medium/cell lipid ratio was 11 times lower, indicating a limited capacity to export newly synthesized lipids. De novo synthesis of apo B-48 and apo B-100 was markedly increased (7%0 and 240%, respectively), whereas the biogenesis of apo A-I was decreased (60%) in Caco-2 cells. The calculated apo B-48/apo B-100 ratio was substantially diminished (107%), suggesting less efficient mRNA editing in Caco-2 cells. When lipoprotein distribution was examined, it displayed a prevalence of VLDL and LDL, accompanied along with a lower proportion of chylomicron and HDL. In addition, differences in lipoprotein composition were evidenced between colonic explants and Caco-2 cells. Therefore, our findings stress the variance in the magnitude of lipid, apolipoprotein and lipoprotein synthesis and secretion between the two intestinal models. This may be due to various factors, including the origin of Caco-2 cell line, i.e., colon carcinoma.
对Caco-2细胞和人结肠外植体在酯化脂质类别、合成载脂蛋白和组装脂蛋白方面的能力进行了比较。将高度分化的细胞和结肠外植体与[¹⁴C]油酸或[³⁵S]甲硫氨酸孵育48小时。Caco-2细胞在将[¹⁴C]油酸掺入细胞磷脂（13倍，P<0.005）、甘油三酯（28倍，P<0.005）和胆固醇酯（2倍，P<0.01）方面表现出更高的能力。然而，它们的培养基/细胞脂质比率低11倍，表明新合成脂质的输出能力有限。Caco-2细胞中载脂蛋白B-48和载脂蛋白B-100的从头合成显著增加（分别为70%和240%），而载脂蛋白A-I的生物合成减少（60%）。计算出的载脂蛋白B-48/载脂蛋白B-100比率大幅降低（107%），表明Caco-2细胞中的mRNA编辑效率较低。当检查脂蛋白分布时，发现以极低密度脂蛋白（VLDL）和低密度脂蛋白（LDL）为主，同时乳糜微粒和高密度脂蛋白（HDL）的比例较低。此外，结肠外植体和Caco-2细胞之间在脂蛋白组成上也存在差异。因此，我们的研究结果强调了两种肠道模型在脂质、载脂蛋白和脂蛋白合成及分泌量方面的差异。这可能是由于多种因素造成的，包括Caco-2细胞系的来源，即结肠癌。
