Molecular Structure and Function, Division of Clinical Biochemistry, Department of Pediatric Laboratory Medicine, Research Institute, The Hospital for Sick Children, 555 University Ave, Toronto, ON, Canada.
J Proteomics. 2010 May 7;73(7):1291-305. doi: 10.1016/j.jprot.2010.01.010. Epub 2010 Feb 1.
Intestinal overproduction of apolipoprotein B (apoB)-48-containing chylomicrons is increasingly recognized as an underlying factor in metabolic dyslipidemia commonly observed in insulin-resistant states. Enhanced chylomicron assembly and secretion has been documented in animal models of insulin resistance, but the underlying mechanistic factors are unknown. Chylomicron assembly occurs through a series of complex vesicular interactions involving prechylomicron transport vesicles (PCTVs), which transport lipids from the endoplasmic reticulum (ER) to the Golgi. We report proteomic profiles of PCTVs isolated from the enteric ER in the small intestine of the fructose-fed hamster, an established model of diet-induced insulin resistance. Using 2D gel electrophoresis and tandem mass spectrometry, PCTVs were characterized and proteomic profiles of PCTV-associated proteins from insulin-resistant and control enterocytes were developed, with the intention of identifying proteins involved in insulin signaling attenuation and lipoprotein overproduction. A number of PCTV-associated proteins were found to be differentially expressed including microsomal triglyceride transfer protein (MTP), apoB-48, Sar1 and VAMP7. We postulate that altered expression of Sar1 and MTP may contribute to increased chylomicron assembly in the fructose-fed hamster. These findings have increased our understanding of the intracellular assembly and transport of nascent chylomicrons and potential cellular factors responsible for lipoprotein overproduction in insulin-resistant states.
肠内载脂蛋白 B（apoB-48）含量较高的乳糜微粒的产生，被认为是胰岛素抵抗状态下常见的代谢性血脂异常的一个潜在因素。在胰岛素抵抗动物模型中，乳糜微粒的组装和分泌得到了增强，但潜在的机制因素尚不清楚。乳糜微粒的组装是通过一系列复杂的囊泡相互作用来实现的，包括前乳糜微粒转运囊泡（PCTV），它将脂质从内质网（ER）运输到高尔基体。我们报告了从小鼠肠道肠内 ER 分离的 PCTV 的蛋白质组学图谱，这是一种饮食诱导胰岛素抵抗的模型。通过二维凝胶电泳和串联质谱，对 PCTV 进行了表征，并对胰岛素抵抗和对照肠细胞的 PCTV 相关蛋白的蛋白质组学图谱进行了开发，目的是鉴定参与胰岛素信号转导减弱和脂蛋白产生过多的蛋白。发现许多 PCTV 相关蛋白的表达存在差异，包括微粒体甘油三酯转移蛋白（MTP）、apoB-48、Sar1 和 VAMP7。我们推测，Sar1 和 MTP 的表达改变可能导致果糖喂养的仓鼠中乳糜微粒组装增加。这些发现增加了我们对新生乳糜微粒的细胞内组装和运输以及胰岛素抵抗状态下脂蛋白产生过多的潜在细胞因素的理解。
