Transport of Lipoprotein Lipase by Heparan Sulfate Proteoglycans

描述（由申请人提供）：脂蛋白脂肪酶是负责水解外周循环中富含甘油三酯的脂蛋白的关键酶。细胞，如心脏和骨骼肌细胞，巨噬细胞和脂肪细胞合成和分泌脂蛋白脂肪酶。然后它穿过基底膜，将这些细胞与组织中的微血管系统分开。酶通过内皮细胞被运送到内皮管腔的作用部位。有证据表明，转运依赖于脂蛋白脂肪酶与硫酸肝素蛋白聚糖的结合。然而，这些研究是在主动脉内皮细胞中进行的，没有生理学相关性，活性硫酸肝素蛋白聚糖的鉴定也没有确定。我们假设，特定的硫酸肝素蛋白多糖驱动脂蛋白脂肪酶从内皮腔侧转运到其在腔侧的作用部位。我们打算通过三个具体目标来验证这一假设：首先，我们将确定与脂蛋白脂肪酶相互作用的相关心脏内皮细胞硫酸肝素蛋白聚糖。接下来，我们将测试脂蛋白脂肪酶在心脏内皮细胞之间的转运是否依赖于硫酸肝素蛋白聚糖。最后，我们将测试脂蛋白脂肪酶是否利用硫酸肝素蛋白聚糖在体内运输，使用携带硫酸肝素生物合成或蛋白聚糖核心蛋白突变的小鼠。

DESCRIPTION (provided by applicant): Lipoprotein lipase is the critical enzyme responsible for the hydrolysis of triglyceride-rich lipoproteins in the peripheral circulation. Cells, such as cardiac and skeletal myocytes, macrophages, and adipocytes synthesize and secrete lipoprotein lipase. It then traverses the basement membrane separating these cells from the microvasculature in the tissue. The enzyme is transported across the endothelial cells to its site of action on the lumen of the endothelium. Evidence suggests that transport depends on lipoprotein lipase binding to heparan sulfate proteoglycans. However, these studies were done in aortic endothelial cells, which are not physiologically relevant, and the identification of the active heparan sulfate proteoglycans was not determined. We hypothesize that specific heparan sulfate proteoglycans drive the transport of lipoprotein lipase from the abluminal side of the endothelium to its site of action on the luminal side. We intend to test this hypothesis through three specific aims: First, we will identify the relevant cardiac endothelial cell heparan sulfate proteoglycans that interact with lipoprotein lipase. Next, we will test if lipoprotein lipase transport across cardiac endothelial cells depends on heparan sulfate proteoglycans. Finally, we will test if lipoprotein lipase utilizes heparan sulfate proteoglycans for transport in vivo using mice bearing mutations in heparan sulfate biosynthesis or proteoglycan core proteins. PUBLIC HEALTH RELEVANCE: Cardiovascular disease is the leading cause of death in the United States. Impairments in the expression, transport, or function of lipoprotein lipase can lead to hypertriglyceridemia, atherosclerosis, and other cardiovascular diseases. These studies will better define the role of heparan sulfate proteoglycans In the trafficking of lipoprotein lipase and will provide insight into the consequences of impaired heparan sulfate proteoglycan- lipoprotein lipase interactions in vivo.