Ceramide Synthases CERS5 and CERS6 Regulate Pathways of Programmed Cell Death

描述（由申请人提供）：与所有生物体一样，人类也会受到环境压力的影响。为了应对这些压力，例如对DMA的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，我们的细胞会被编程为杀死自己，这一过程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起着重要作用;过度的程序性细胞死亡导致与缺血性心脏病和中风相关的显著发病率和死亡率，而有缺陷的细胞死亡导致美国第二大死亡原因癌症。鞘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脂，是程序性细胞死亡的重要介质。神经酰胺由神经酰胺脱氢酶（CerSes）在细胞死亡期间产生，并且有越来越多的证据表明这些酶在调节神经酰胺产生和细胞死亡中发挥特定作用。然而，CerS和神经酰胺介导的细胞死亡的机制是不明确的，需要进一步研究。通过了解这些途径的细节，我们将能够确定治疗目标。该项目的目标是确定CerSS和CerS 6在介导程序性细胞死亡中的作用。本项目将利用MCF-7乳腺癌细胞系研究CerSS和CerS 6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CerSS和CerS 6介导的神经酰胺产生的下游靶标。本研究的目的是1）确定CerSS和CerS 6如何调节细胞死亡; 2）确定CerSS和CerS 6在细胞死亡期间如何调节; 3）确定CerSS或CerS 6介导的神经酰胺产生是否足以激活细胞死亡途径（例如Bax）。这些研究的主要方法将是过表达或敲低CerSS和CerS 6，并检查随后对Bax激活和其他细胞死亡参数的影响。该项目代表了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的一个渐进步骤。人类细胞对过度压力的反应是做出自杀的决定。该项目旨在确定脂质神经酰胺和制造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.