Ceramide Synthases CERS5 and CERS6 Regulate Pathways of Programmed Cell Death

描述(申请人提供)：人类，像所有生物体一样，容易受到环境压力的影响。为了应对这些压力，例如DNA损伤或蛋白质和脂质的氧化，我们的细胞具有许多保护机制(例如DMA修复或抗氧化系统)。然而，当压力变得太大时，我们的细胞就会被编程杀死--这一过程被称为程序性细胞死亡或凋亡。程序性细胞死亡在人类健康和疾病中发挥着重要作用；过度的程序性细胞死亡会导致与缺血性心脏病和中风相关的显著发病率和死亡率，而在美国，缺陷细胞死亡导致第二大死亡原因是癌症。鞘磷脂是细胞生长和死亡的重要调节因子。神经酰胺是一种具有生物活性的鞘磷脂，是细胞程序性死亡的重要介质。神经酰胺是由神经酰胺合成酶(CerSes)在细胞死亡过程中产生的，越来越多的证据表明这些酶在调节神经酰胺的产生和细胞死亡中发挥着特定的作用。然而，CERs和神经酰胺介导的细胞死亡机制尚不清楚，值得进一步研究。通过了解这些通路的细节，我们将能够识别感兴趣的治疗靶点。本项目的目的是确定CerSS和CerS6在调节细胞程序性死亡中的作用。本项目将利用MCF-7乳腺癌细胞株来研究CerSS和CerS6在遗传毒性应激紫外线(UVC)诱导的细胞死亡中的作用。在初步研究中，促死亡蛋白Bax已成为在UVC诱导的死亡中CerSS和CerS6介导的神经酰胺产生的下游靶点。这项研究的目的是1)确定CerSS和CerS6如何调控细胞死亡；2)确定CerSS和CerS6在细胞死亡过程中如何调控；3)确定CerSS或CerS6介导的神经酰胺产生是否足以激活细胞死亡途径(如Bax)。这些研究的主要方法将是过表达或敲除CerSS和CerS6，并检查随后对Bax激活和其他细胞死亡参数的影响。这个项目代表着我们在实现确定神经酰胺介导的程序性细胞死亡机制的长期目标方面迈出的渐进的一步。人类细胞对过度压力的反应是决定自杀。这个项目试图确定脂质神经酰胺和使神经酰胺的酶如何调节这一决定。

DESCRIPTION (provided by applicant): Humans, like all organisms, are subject to environmental stresses. To deal with these stresses, such as damage to the DMA or oxidation of proteins and lipids, our cells possess numerous protective mechanisms (e.g. DMA repair or anti-oxidant systems). However, when stresses become too great, our cells are programmed to kill themselves-a process called programmed cell death or apoptosis. Programmed cell death plays important roles in human health and disease; excessive programmed cell death leads to the significant morbidity and mortality associated with ischemic heart disease and stroke, whereas defective cell death leads to the second greatest cause of mortality in the United States, cancer. Sphingolipids are important regulators of cell growth and death. Ceramide, a bioactive sphingolipid, is an essential mediator of programmed cell death. Ceramide is produced by ceramide synthases (CerSes) during cell death, and there is an accumulating body of evidence that these enzymes play specific roles in regulating ceramide generation and cell death. However, the mechanisms of CerS- and ceramide-mediated cell death are ill-defined and warrant further study. By understanding the details of these pathways we will be able to identify targets of therapeutic interest. The goal of this project is to determine the role of CerSS and CerS6 in mediating programmed cell death. This project will utilize the MCF-7 breast adenocarcinoma cell line to investigate the contribution of CerSS and CerS6 to cell death induced by the genotoxic stress ultraviolet light (UVC). In preliminary investigations, the pro-death protein Bax has emerged as a downstream target of CerSS and CerS6- mediated ceramide production in UVC-induced death. The aims of this study are 1) determine how CerSS and CerS6 regulate cell death; 2) determine how CerSS and CerS6 are regulated during cell death; and 3) determine whether CerSS or CerS6-mediated ceramide production is sufficient to activate cell death pathways (e.g Bax). The primary methodology of these studies will be to overexpress or knockdown CerSS and CerS6 and examine subsequent effects on Bax activation and other parameters of cell death. This project represents an incremental step in achieving our long-term goal of determining the mechanisms of ceramide-mediated programmed cell death. Human cells respond to excessive stress by making a decision to kill themselves. This project seeks to determine how the lipid ceramide and the enzymes that make ceramide regulate this decision.