Membrane Targeting by Phosphoinositide Binding Proteins

描述（由申请人提供）：在生物学和医学领域中，越来越难以找到膜脂质不发挥重要的信号传导和调节作用的领域。磷脂酰肌醇的磷酸化衍生物，统称为磷酸肌醇（PtdInsPs），在不同的细胞过程中发挥关键作用。PtdInsP介导的细胞调节的重要性已经通过与PtdInsP信号传导缺陷相关的许多人类疾病（包括癌症、糖尿病和炎性疾病）证明。因此，PtdInsP介导的细胞信号传导途径是药物开发的主要目标。然而，人们仍然知之甚少PtdInsPs如何特异性地调节这些不同的细胞过程，并且缺乏这种基本的理解极大地破坏了开发针对PtdInsP信号传导途径的特异性和有效的治疗剂的努力。基于我们最近的研究，我们假设局部PtdInsP浓度作为差异激活阈值，触发不同的下游细胞过程。这项研究的主要目的是调查复杂的机制，不同的PtdInsP介导的细胞调控的基础上，这个可测试的假设，并使用我们新开发的脂质传感器技术，允许在原位定量PtdInsP在活组织。 具体而言，我们建议（1）开发新的荧光探针和成像技术，用于单独和组合定量哺乳动物细胞中的PtdInsPs，（2）确定两种关键信号脂质，磷脂酰肌醇-3，4，5-三磷酸和磷脂酰肌醇-3，4-二磷酸的差异细胞调节机制，以及（3）确定另一种重要脂质，磷脂酰丝氨酸的作用，在磷脂酰肌醇3，4，5-三磷酸信号传导中。

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.