Light regulation of retinal phosphoinositides

 说明(申请人提供)：磷脂酰肌醇是一种低丰度的膜磷脂，它是一系列膜相关蛋白的重要识别位点，参与细胞内信号转导级联反应，以及细胞内膜生物发生、稳态和运输。以前，它们的低丰度阻碍了对它们在视网膜光感受器神经元中水平的量化，但我们最近开发了一种方法，可以准确地测量前所未有的灵敏度。这些测量表明，光诱导的PI(4，5)P2、其前体PI(4)P和PI(3)P的水平显著增加，而PI(3，4，5)P3的水平没有明显增加。这些结果与以前关于光驱动的PI(4，5)P2减少以及PI-3激酶亚型的光激活产生PI(3，4和5)P3的报道相反，它们揭示了光感受器中先前未知的光反应途径。由产生PI(3)P的III型PI-3激酶的杆状特异性敲除引起的视网膜变性强调了磷脂酰肌醇合成的生理重要性。我们将使用一系列技术来操纵光感受器中脂代谢酶的基因表达或活性，以及对视网膜结构的多尺度分析、视网膜功能的电生理和行为测量，以及我们对特定磷脂酰肌醇进行量化和定位的创新方法，以确定光感受器磷脂酰肌醇水平调节的分子机制及其在视网膜功能、健康和疾病中的作用。

 DESCRIPTION (provided by applicant): Phosphoinositides are low-abundance membrane phospholipids which act as important recognition sites for a host of membrane associated proteins involved in intracellular signal transduction cascades, and in intracellular membrane biogenesis, homeostasis, and trafficking. Previously, their low abundance has precluded quantification of their levels in retinal photoreceptor neurons, but we have recently developed methods that allow accurate measurements of unprecedented sensitivity. These measurements have revealed striking light-induced increases in levels of PI(4,5)P2, its precursor, PI(4)P, and PI(3)P, without measurable increases in PI(3,4,5)P3. These results contrast with previous reports of light driven decreases in PI (4, 5) P2, and light activation of a PI-3 kinase isoform tht produces PI (3, 4, and 5) P3, and they reveal previously unknown pathways of light responses in photoreceptors. Retinal degeneration induced by a rod-specific knockout of the type III PI-3 kinase which produces PI (3) P underscores the physiological importance of phosphoinositide synthesis. We will use a range of techniques to manipulate gene expression or activity of enzymes of lipid metabolism in photoreceptors, along with multi-scale analysis of retinal structure, electrophysiological and behavioral measures of retinal function, and our innovative methods for quantifying and localizing specific phosphoinositides, to determine the molecular mechanisms for regulation of photoreceptor phosphoinositide levels and their roles in retinal function, health, and disease.