Ceramide Activated Protein Phosphatases

神经酰胺组成了一个密切相关的分子家族，其功能是 生物效应脂在应激反应和细胞生长/死亡调节中的作用 各种人类癌细胞。我们对神经酰胺认识中的关键缺失元素 源于缺乏分子上定义的作用靶点和定义 神经酰胺的隔室特有功能。由该项目支持的实验室研究 已发现神经酰胺激活的丝氨酸苏氨酸磷酸酶(CAPP)，特别是PP1和 PP2A作为神经酰胺体外激活的直接靶点。对细胞的研究也表明 神经酰胺诱导的各种刺激(如肿瘤坏死因子、紫外线、脂毒剂)诱导 几种底物以神经酰胺依赖的方式去磷酸化。然而，不是 所有刺激诱导所有去磷酸化，可能是由于它们激活了不同的 在不同的亚细胞室中的通路。最近的结果为我们提供了一个 在确定血浆中神经酰胺生成的特定途径方面取得突破 膜(PM)。在这里，我们将调查神经酰胺产生于 PM敏锐地激活PP1cα，导致Ezrin和其他 蛋白质。这导致神经酰胺在调节细胞中具有隔室特异性作用。 黏附和迁移。我们将解决这些目标：目标1.定义一条新的途径 PM中神经酰胺的生成通过激活Ezrin去磷酸化 PP1cα。在这里，我们将调查PM神经酰胺调节A 不依赖RAFT的二聚体PP1c介导Ezrin去磷酸化的特定形式 队形。目标2.确定与分区相结合的特定蜂窝程序 神经酰胺/CAPPS。在这里，我们将调查PM神经酰胺， 与其他隔室中形成的神经酰胺不同，神经酰胺调节细胞黏附和 迁移。综上所述，这些方法应该第一次产生明确的 为神经酰胺作用(PP1)定义特定的、直接的和相关的靶点 PM神经酰胺在介导细胞黏附和迁移中的作用。

Ceramide constitutes a family of closely related molecules that function as bioeffector lipids with roles in the regulation of stress responses and growth/death of various human cancer cells. Critical missing elements in our understanding of ceramide stems from the lack of molecularly-defined targets of action and from defining compartment-specific functions of ceramides. Studies in our lab supported by this project have identified ceramide-activated Ser–Thr phosphatases (CAPPs), specifically PP1 and PP2A as direct targets activated by ceramide in vitro. Studies in cells have also shown that various ceramide-inducing stimuli (e.g. TNF, UV, lipotoxic agents) induce dephosphorylation of several substrates in a ceramide-dependent manner. However, not all stimuli induce all dephosphorylations, presumably due to their activation of distinct pathways in distinct subcellular compartments. Recent results have provided us a breakthrough in defining a specific pathway of ceramide generation at the plasma membrane (PM). Here, we will investigate the hypothesis that ceramide generated at the PM acutely activates PP1cα that leads to the dephosphorylation of ezrin and other proteins. This results in a compartment-specific role for ceramide in regulating cell adhesion and migration. We will address these aims: Aim 1. Define a novel pathway of ceramide generation at the PM leading to ezrin dephosphorylation though activation of PP1cα. Here we will investigate the specific hypothesis that PM ceramide regulates a specific form of dimeric PP1c to mediate ezrin dephosphorylation, independent of raft formation. Aim 2. Identify specific cellular programs coupled to compartmentalized ceramide/CAPPs. Here we will investigate the specific hypothesis that PM ceramide, in contrast to ceramide formed in other compartments, regulates cell adhesion and migration. Taken together, these approaches should result, for the first time, in clearly defining a specific, direct, and relevant target for ceramide action (PP1) with a specific function in mediating the effects of PM ceramide on cell adhesion and migration.