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脂代谢的特定途径，定义特定作用，定义机制，并帮助将生物活性脂质领域置于坚实的机制基础上。基于强有力的正在进行的数据，我们提出了整体假设，神经酰胺代谢的个别酶作为特定输入的换能器，和产品的生物活性鞘脂功能介导的关键反应。该建议将在DNA损伤反应和其他刺激物激活不同隔室中的中性鞘磷脂酶导致形成主要在细胞周期检查点中起作用的神经酰胺的情况下开发这种范例。我们提出以下具体目标：1.诱导nSMase2和Isc 1的机制是什么？2. nSMase2和Isc 1在细胞核中是如何被激活的？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.细胞核中脂质的结构是什么？5. nSMase 2（和Isc 1）在检查点中的具体功能是什么？6.核磷酸酶介导核神经酰胺的作用吗？其机制是什么？7.定义酵母中生物活性鞘脂的平行途径。总之，我们奋进推进我们对生物活性鞘脂的理解，并将其复杂性降低到可管理和特定的组分，这些组分有望揭示这些特定途径如何发挥作用及其在应激反应中的特定作用。正在进行的研究结果确定了一个完全出乎意料的作用，中性鞘磷脂酶在真核DNA损伤反应，通过核脂质介导的途径。

 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.