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通过特异性地去磷酸化一个关键的调控残基（疏水基序）来终止Akt和蛋白激酶C两种致癌激酶的信号传导，我们最初在蛋白激酶C上发现了疏水基序。PHLPP在多种人类癌症中经常缺失，在小鼠中其缺失会促进前列腺肿瘤。因此，推动这一提议的中心假设是PHLPP终止生长信号通路，而放松管制导致病理生理状态，特别是癌症。提出了三个目标：1。PHLPP的分子机制。目标是确定PHLPP的小分子抑制剂或激活剂，作为目标2和目标3中细胞研究的工具。此外，我们将验证PHLPP中癌症相关突变失活的假设，从而赋予肿瘤细胞生存优势。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验证PDZ支架NHERF上的空间协调增加了PHLPP控制Akt信号的振幅和持续时间的能力。其次，我们将探讨PHLPP抑制细胞中生长因子受体水平的机制。3. 病理生理学中的PHLPP。本研究旨在探讨PHLPP在癌症中的作用。具体来说，我们将验证E3连接酶2-TrCP对PHLPP的解除管制有助于胶质母细胞瘤的假设。此外，我们将通过小鼠模型和3D培养模型解决PHLPP1和PHLPP2在前列腺癌和乳腺细胞生长中的作用。

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.