Membrane Targeting by Phosphoinositide Binding Proteins

描述(申请人提供)：在生物学和医学领域，越来越难找到膜脂不起重要信号和调节作用的领域。磷脂酰肌醇的磷酸化衍生物，统称为磷脂酰肌醇(PtdInsPs)，在不同的细胞过程中发挥着关键作用。PtdInsP介导的细胞调控的重要性已经被许多与PtdInsP信号缺陷有关的人类疾病所证明，包括癌症、糖尿病和炎症性疾病。因此，PtdInsP介导的细胞信号通路是药物开发的主要靶点。然而，目前对PtdInsp如何具体调控这种不同的细胞过程仍知之甚少，缺乏这种基本的理解极大地破坏了开发针对PtdInsP信号通路的特定和有效的治疗剂的努力。根据我们最近的研究，我们假设局部PtdInsP浓度作为不同的激活阈值，触发不同的下游细胞过程。这项研究的主要目的是在可检验假说的基础上，利用我们最新开发的脂传感器技术，在活细胞中原位定量PtdInsP，以探讨PtdInsP介导的各种细胞调控的复杂机制。 具体地说，我们建议(1)开发新的荧光探针和成像技术来单独和联合定量哺乳动物细胞中的PtdInsPs；(2)确定两种关键信号脂类--磷脂酰肌醇3，4，5-三磷酸和磷脂酰肌醇-3，4-二磷酸对细胞的调控机制；以及(3)确定另一种重要的脂质--磷脂酰丝氨酸在磷脂酰肌醇3，4，5-三磷酸信号转导中的作用。

DESCRIPTION (provided by applicant): It has become increasingly difficult to find an area of biology and medicine in which membrane lipids do not play important signaling and regulatory roles. Phosphorylated derivatives of phosphatidylinositol, collectively known as phosphoinositides (PtdInsPs), play key roles in diverse cellular processes. The importance of PtdInsP-mediated cell regulation has been demonstrated by numerous human diseases linked to defects in PtdInsP signaling, including cancer, diabetes, and inflammatory diseases. Consequently, the PtdInsP-mediated cell signaling pathways are major targets for drug development. However, it is still poorly understood how PtdInsPs specifically regulate such diverse cellular processes and the lack of this fundamental understanding greatly undermines the effort to develop specific and potent therapeutic agents targeted against PtdInsP signaling pathways. Based on our recent studies, we hypothesize that local PtdInsP concentrations act as differential activation thresholds, triggering diverse downstream cellular processes. The primary objective of this proposed research is to investigate the complex mechanisms underlying diverse PtdInsP-mediated cell regulation on the basis of this testable hypothesis and using our newly developed lipid sensor technology that allows in situ quantification of PtdInsP in live cels. Specificaly, we propose to (1) develop new fluorescence probes and imaging techniques for quantifying PtdInsPs in mammalian cells, individually and in combination, (2) determine the mechanisms of differential cell regulation by two key signaling lipids, phosphatidylinositol 3,4,5-trisphosphate and phosphatidylinositol-3,4- bisphosphate, and (3) determine of the role of another important lipid, phosphatidylserine, in phosphatidylinositol 3,4,5-trisphosphate signaling.