Light regulation of retinal phosphoinositides

 描述（由申请人提供）：磷脂酰肌醇是低丰度膜磷脂，其作为参与细胞内信号转导级联以及细胞内膜生物发生、稳态和运输的许多膜相关蛋白的重要识别位点。以前，它们的低丰度已经排除了它们在视网膜感光神经元中的水平的定量，但是我们最近开发了允许精确测量前所未有的灵敏度的方法。这些测量揭示了PI（4，5）P2、其前体、PI（4）P和PI（3）P水平的显著光诱导增加，而PI（3，4，5）P3没有可测量的增加。这些结果与先前报道的PI（4，5）P2的光驱动降低以及产生PI（3，4和5）P3的PI-3激酶同种型的光活化形成对比，并且它们揭示了光感受器中先前未知的光响应途径。由产生PI（3）P的III型PI-3激酶的视杆特异性敲除诱导的视网膜变性强调了磷酸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质代谢酶的基因表达或活性，沿着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，以及我们用于定量和定位特定磷酸肌醇的创新方法，以确定调节光感受器磷酸肌醇水平的分子机制及其在视网膜功能，健康，和疾病

 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.