Ceramide Activated Protein Phosphatases

神经酰胺构成了一个密切相关的分子家族， 生物效应脂质在调节应激反应和生长/死亡中的作用 各种人类癌细胞。我们对神经酰胺理解中的关键缺失元素 源于缺乏分子定义的行动目标， 神经酰胺的区室特异性功能。本项目支持的实验室研究 已经鉴定了神经酰胺激活的丝氨酸-苏氨酸磷酸酶（CAPP），特别是PP 1和 PP 2A作为神经酰胺体外激活的直接靶点。对细胞的研究也表明 各种神经酰胺诱导刺激（例如TNF、UV、脂毒性剂）诱导 以神经酰胺依赖性方式对几种底物进行去磷酸化。但并非 所有刺激都诱导所有的去磷酸化，可能是由于它们激活了不同的 在不同的亚细胞区室的途径。最近的结果为我们提供了一个 在定义血浆中神经酰胺产生的特定途径方面取得突破 膜（PM）。在这里，我们将调查的假设，神经酰胺产生在 PM急性激活PP 1c α，导致ezrin和其他蛋白的去磷酸化， proteins.这导致神经酰胺在调节细胞凋亡中具有特定的作用。 粘附和迁移。我们将实现这些目标：目标1。定义一种新的途径， 在PM产生神经酰胺，导致ezrin去磷酸化， PP1cα。在这里，我们将调查的具体假设，PM神经酰胺调节一个 二聚体PP 1c介导ezrin去磷酸化的特定形式，独立于筏 阵目标二。识别特定的细胞程序， 神经酰胺/CAPP。在这里，我们将调查的具体假设，PM神经酰胺， 与在其它隔室中形成的神经酰胺相反，调节细胞粘附， 迁移这些方法合在一起，应首次明确地 用特定的神经酰胺作用（PP 1）定义特定的、直接的和相关的靶点， 在介导PM神经酰胺对细胞粘附和迁移的作用中起作用。

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.