Sphingolipid Biology And Disease

鞘脂生物学与疾病

• 批准号: 6810537
• 负责人: RICHARD L. PROIA
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6810537
• 关键词: G protein; Gaucher's disease; Niemann Pick disease; Sandhoff disease; Tay Sachs disease; gangliosidosis; human tissue; laboratory mouse; lipid metabolism; neural degeneration; pathologic process; receptor coupling; sphingolipidosis; sphingolipids; sphingosine

Sphingolipids are important mediators and regulators of cell signaling pathways. Our studies have focused on the actions of two classes of sphingolipids represented by glycosphingolipids (GSLs) and sphingosine-1-phosphate. Our work is aimed at defining the normal functions of these sphingolipids and understanding their roles in disease processes. GSLs are found in the outer leaflet of the plasma membrane and are concentrated in specialized signaling structures. They are particularly abundant in neuronal cells in the form of gangliosides (sialic acid containing GSLs). Through genetic disruption of genes that encode synthetic enzymes for GSLs, we have created a series of mice that express limited glycosphingolipid structures. We are using these mice to discover the functions of GSLs. When the cellular machinery responsible for GSL degradation is defective, GSL storage diseases result in which profound neurodegeneration occurs. Examples are Tay-Sachs and Gaucher diseases. We are attempting to understand how the accumulation of GSLs cause neurodegeneration through the construction of animal models of the diseases. Our major accomplishments this year include the establishment of mutant mice that lack GM3 synthase (CMP-NeuAc:lactosylceramide alpha2,3-sialyltransferase; EC 2.4.99.-). These mutant mice were unable to synthesize GM3 ganglioside, a simple and widely distributed glycosphingolipid. The mutant mice were viable and appeared without major abnormalities but showed a heightened sensitivity to insulin. A basis for the increased insulin sensitivity in the mutant mice was found to be enhanced insulin receptor phosphorylation in skeletal muscle. Importantly, the mutant mice were protected from high-fat diet-induced insulin resistance. We also continued our studies on the G-protein coupled receptor for sphingosine-1-phosphate, S1P1. We had previously shown the the global knockout of S1P1 in mice caused defective coverage of blood vessels by vascular smooth muscle cells (VSMCs). Since S1P1 receptor expression is not restricted to a particular cell type, it was not known whether the S1P1 receptor controlled VSMC coverage of vessels in a cell-autonomous fashion by functioning directly in VSMCs or indirectly through its activity in endothelial cells (ECs). By using the Cre/loxP system, we disrupted the S1P1 gene solely in ECs. The phenotype of the conditional mutant embryos mimicked the one obtained in the embryos globally deficient in S1P1. Thus, vessel coverage by VSMCs is directed by the activity of the S1P1 receptor in ECs.

鞘脂是细胞信号通路的重要介质和调节剂。我们的研究集中在两类鞘脂的作用，代表鞘糖脂（GSL）和鞘氨醇-1-磷酸。我们的工作旨在定义这些鞘脂的正常功能，并了解它们在疾病过程中的作用。GSL存在于质膜的外小叶中，并集中在专门的信号结构中。它们以神经节苷脂（含唾液酸的GSL）的形式在神经元细胞中特别丰富。通过对编码GSL合成酶的基因进行遗传破坏，我们创造了一系列表达有限鞘糖脂结构的小鼠。我们正在使用这些小鼠来发现GSL的功能。当负责GSL降解的细胞机制有缺陷时，GSL储存疾病导致发生严重的神经变性。例如Tay-Sachs和Gaucher病。我们正试图通过建立疾病的动物模型来了解GSL的积累如何导致神经退行性变。 我们今年的主要成就包括建立缺乏GM 3合酶（CMP-NeuAc：乳糖神经酰胺α 2，3-唾液酸转移酶; EC 2.4.99.-）的突变小鼠。这些突变小鼠不能合成GM 3神经节苷脂，一种简单且广泛分布的鞘糖脂。突变小鼠是可行的，似乎没有重大异常，但显示出对胰岛素的敏感性提高。发现突变小鼠胰岛素敏感性增加的基础是骨骼肌中胰岛素受体磷酸化增强。重要的是，突变小鼠受到保护，免受高脂肪饮食诱导的胰岛素抵抗。 我们还继续对鞘氨醇-1-磷酸的G蛋白偶联受体S1 P1进行了研究。我们之前已经证明了小鼠中S1 P1的整体敲除导致血管平滑肌细胞（VSMCs）对血管的覆盖缺陷。由于S1 P1受体表达不限于特定的细胞类型，因此尚不清楚S1 P1受体是否通过直接在VSMC中起作用或间接通过其在内皮细胞（EC）中的活性以细胞自主方式控制VSMC对血管的覆盖。通过使用Cre/loxP系统，我们仅在EC中破坏S1 P1基因。条件突变体胚胎的表型模仿在S1 P1全面缺陷的胚胎中获得的表型。因此，血管平滑肌细胞的血管覆盖率是由内皮细胞中S1 P1受体的活性决定的。