Neutral sphingomyelinases and bioactive ceramides

 描述(由申请人提供)：本研究提案的总体目标是定义鞘磷脂代谢的特定途径，定义特定的角色，定义机制，并帮助将生物活性脂质领域置于坚实的机械基础上。基于强大的持续数据，我们提出了一个总体假设，即神经酰胺代谢的单个酶充当特定输入的转导，而产物具有生物活性的鞘磷脂起中介关键反应的作用。这一建议将在DNA损伤反应和其他刺激激活不同间隔中的中性鞘磷脂酶导致神经酰胺形成的情况下发展这一范式，神经酰胺主要作用于细胞周期检查点。我们提出了以下具体目标：1.nSMase2和Isc1的诱导机制是什么？2.nSMase2和Isc1在细胞核中是如何激活的？细胞核PIP2是否有特定的作用？3.定义中性鞘磷脂酶的调节机制和结构4.细胞核中的脂类结构是什么？5.检查点中nSMase2(和Isc1)的特殊功能是什么？6.核磷酸酶是否介导了核神经酰胺的作用；涉及的机制是什么？7.确定酵母中具有生物活性的鞘磷脂的平行通路。综上所述，我们努力提高我们对生物活性鞘脂的理解，并将其复杂性降低到易于处理和特定的成分，这些成分有望为这些特定途径如何发挥作用以及它们在应激反应中的具体作用提供重要的线索。正在进行的结果定义了中性鞘磷脂酶在真核细胞DNA损伤反应中通过核脂介导的途径发挥的完全意想不到的作用。

 DESCRIPTION (provided by applicant): The overall goals of this research proposal are to define specific pathways of sphingolipid metabolism, define specific roles, define mechanisms, and help place the field of bioactive lipids on solid mechanistic grounds. Based on strong ongoing data, we propose the overall hypothesis that individual enzymes of ceramide metabolism serve as transducers of specific inputs, and the product bioactive sphingolipids function to mediate key responses. This proposal will develop this paradigm in the case of the DNA damage response and other stimuli activating neutral sphingomyelinases in distinct compartments leading to formation of ceramide which acts primarily in a cell cycle checkpoint. We propose the following specific goals: 1. What are the mechanisms involved in induction of nSMase2 and Isc1? 2. How are nSMase2 and Isc1 activated in the nucleus? Is there a specific role for nuclear PIP2? 3. Define mechanisms of regulation and the structure of neutral sphingomyelinases 4. What is the structure of lipids in the nucleus? 5. What is the specific function of nSMase2 (and Isc1) in checkpoints? 6. Do nuclear phosphatases mediate the action of nuclear ceramide; what are the mechanisms involved? 7. Define parallel pathways of bioactive sphingolipids in yeast. Taken together, we endeavor to advance our understanding of bioactive sphingolipids and reduce its complexities to manageable and specific components that promise to shed important light on how these specific pathways function, and their specific roles in stress responses. The ongoing results are defining a totally unexpected role for neutral sphingomyelinases in the eukaryotic DNA damage response through a nuclear lipid-mediated pathway.