SPHINGOLIPIDS AS SIGNALS FOR TUMOR NECROSIS FACTOR-A

鞘脂作为肿瘤坏死因子 A 的信号

• 批准号: 3201744
• 负责人: Richard N Kolesnick
• 金额: $ 15.24万
• 依托单位: SLOAN-KETTERING INST CAN RESEARCH
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-01 至 1995-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3201744
• 关键词: biological signal transduction; ceramides; clone cells; cytokine receptors; cytotoxicity; enzyme activity; lipid metabolism; phosphorylation; protein kinase; receptor coupling; sphingolipids; sphingomyelins; tumor necrosis factor alpha

The general goal of this grant proposal is to define a signal transduction pathway for tumor necrosis factor (TNF)-alpha. This cytokine is a principal host defense against foreign antigen and may serve a variety of physiologic regulatory functions. Although a number of reports have suggested a role for one of the known signalling systems, no coherent picture has emerged for a second messenger pathway that may account for the entirety of the pleiotropic effects of TNF-alpha. This proposal is based on the recent observation that sphingomyelin degradation to ceramide is an early event in TNF-alpha action in human promyelocytic leukemia (HL-60) cells and that ceramide may substitute for TNF-alpha in monocytic differentiation. During the past few years, this laboratory has described a new metabolic pathway involving sphingomyelin and its derivatives. This pathway is initiated by hydrolysis of plasma membrane sphingomyelin to ceramide by the action of a sphingomyelinase. Subsequently, ceramide may be de-acylated to sphingosine, an inhibitor of protein kinase C, or phosphorylated to ceramide 1-phosphate, a compound newly discovered in this laboratory. Because of apparent similarities between this metabolic pathway and the phosphoinositide pathway, it was postulated that ceramide may serve second messenger function. Indeed, a cell-permeable ceramide analog induced selective phosphorylation of the epidermal growth factor receptor on threonine 669. Based on this observation, this laboratory has recently characterized a novel kinase that mediates this action of ceramide, termed ceramide-activated protein kinase, in membranes derived from HL-60 and A431 human epidermoid carcinoma cells. Elevation of ceramide levels by TNF-alpha also resulted in enhanced kinase activity in membranes derived from stimulated cells. The specific aims of this grant are to: (1) demonstrate that this sphingomyelin pathway is tightly coupled to activation of the TNF receptor both in intact cells and in vitro: (2) show that this pathway is sufficient to mediate TNF-alpha-induced protein phosphorylation; and (3) generalize this pathway to various models of TNF- alpha action and in particular determine how it might relate to TNF-induced cytotoxicity and cytostasis. Hopefully, these studies will provide fundamental insights into the mechanism of TNF-alpha action and allow for eventual pharmacologic manipulation of this system.

这项拨款提案的总体目标是定义一种信号转导 肿瘤坏死因子（TNF）-α的途径。 这种细胞因子是一种 主要宿主防御外来抗原，可用于多种 生理调节功能。 虽然有一些报告 提出了一个已知的信号系统的作用，没有连贯的 第二信使途径的图像已经出现，这可能解释了 TNF-α的多效性的全部。 该提案基于 根据最近的观察，鞘磷脂降解为神经酰胺是一种 人早幼粒细胞白血病（HL-60）中TNF-α作用的早期事件 神经酰胺可以替代单核细胞中的TNF-α， 分化 在过去的几年里，这个实验室已经描述了 涉及鞘磷脂及其衍生物的新代谢途径。 这 途径由质膜鞘磷脂水解启动， 神经酰胺通过鞘磷脂酶的作用。 随后，神经酰胺可 去酰化为鞘氨醇，一种蛋白激酶C的抑制剂，或 磷酸化为神经酰胺1-磷酸，这是一种新发现的化合物， 实验室 由于这种代谢和 途径和磷酸肌醇途径，假设神经酰胺 可以作为第二信使。 事实上，一种可渗透细胞的神经酰胺 类似物诱导的表皮生长因子的选择性磷酸化 第669章. 根据这一观察，该实验室 最近发现了一种新的激酶，它介导了 神经酰胺，称为神经酰胺活化蛋白激酶，在膜衍生 HL-60和A431人表皮样癌细胞。 标高 神经酰胺水平的TNF-α也导致增强的激酶活性， 膜来源于刺激的细胞。 该补助金的具体目的 目的是：（1）证明该鞘磷脂途径是紧密偶联的， TNF受体在完整细胞和体外的活化：（2） 显示该途径足以介导TNF-α诱导蛋白 磷酸化;和（3）将该途径推广到TNF-α的各种模型。 α作用，特别是确定它如何与TNF诱导的 细胞毒性和细胞抑制。 希望这些研究能提供 对TNF-α作用机制的基本见解，并允许 最终对该系统进行药理学操作。