Signal Termination by PHLPP, PH domain Leucine-rich repeat Protein Phosphatase

描述（由申请人提供）：本提案的长期目标是了解我们发现的新型磷酸酶PHLPP（PH结构域富含亮氨酸重复蛋白磷酸酶;发音为“flip”）介导的信号终止的分子、细胞和生理机制。PHLPP通过特异性去磷酸化我们最初在蛋白激酶C上鉴定的一个关键调节残基--疏水基序来终止两种致癌激酶Akt和蛋白激酶C的信号传导。PHLPP在多种人类癌症中经常缺失，并且其在小鼠中的缺失促进前列腺肿瘤。因此，推动这一提议的中心假设是PHLPP终止生长信号传导途径，并且失调导致病理生理状态，特别是癌症。提出了三个目标：1。PHLPP的分子机制目标是鉴定PHLPP的小分子抑制剂或激活剂，以用作目标2和3中的细胞研究中的工具。此外，我们将检验PHLPP中癌症相关突变失活并因此赋予肿瘤细胞存活优势的假设。2. PHLPP的细胞机制。本节的目的是了解控制细胞中PHLPP功能的机制。首先，我们将使用创新的活细胞成像技术来测试PDZ支架NHERF上的空间协调增加PHLPP控制Akt信号传导的幅度和持续时间的能力的假设。其次，我们将讨论PHLPP抑制细胞中生长因子受体水平的机制。3. PHLPP在病理生理学。该目的解决了PHLPP在癌症中的作用。具体而言，我们将测试这一假设，即PHLPP的E3连接酶2-TrCP的失调有助于胶质母细胞瘤。此外，我们将使用小鼠模型和乳腺细胞生长中使用3D培养模型来解决PHLPP 1和PHLPP 2在前列腺癌中的作用。

DESCRIPTION (provided by applicant): The long-term goal of this proposal is to understand the molecular, cellular and physiological mechanisms of signal termination mediated by the novel phosphatase PHLPP (PH domain Leucine- rich repeat Protein Phosphatase; pronounced 'flip') that we discovered. PHLPP terminates signaling by two oncogenic kinases, Akt and protein kinase C, by specifically dephosphorylating a key regulatory residue, the hydrophobic motif, which we originally identified on protein kinase C. PHLPP is frequently deleted in diverse human cancers and its deletion in mice promotes prostate tumors. Thus, the central hypothesis driving this proposal is that PHLPP terminates growth signaling pathways and that deregulation leads to pathophysiological states, notably cancer. Three Aims are proposed: 1. Molecular Mechanisms of PHLPP. The goals are to identify small molecule inhibitors or activators of PHLPP to use as tools in cellular studies in Aims 2 and 3. In addition, we will test the hypothesis that cancer-associated mutations in PHLPP are inactivating and thus confer a survival advantage to tumor cells. 2. Cellular Mechanisms of PHLPP. The goal of this section is to understand the mechanisms that control the function of PHLPP in cells. First, we will use innovative live cell imaging technologies to test the hypothesis that spatial coordination on the PDZ scaffold NHERF increases the ability of PHLPP to control the amplitude and duration of Akt signaling. Second, we will address the mechanism by which PHLPP suppresses the levels of growth factor receptors in cells. 3. PHLPP in pathophysiology. This Aim addresses the role of PHLPP in cancer. Specifically, we will test that hypothesis that deregulation of PHLPP by the E3 ligase 2-TrCP contributes to glioblastoma. In addition, we will address the roles of PHLPP1 and PHLPP2 in prostate cancer using a mouse model and in breast cell growth using a 3D culture model.