The Role of Merlin Phosphorylation on its Tumor Suppressive Activity

Merlin 磷酸化对其肿瘤抑制活性的作用

• 批准号: 7196481
• 负责人: KEQIANG YE
• 金额: $ 20.73万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-08 至 2011-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7196481
• 关键词: 1-Phosphatidylinositol 3-Kinase; Accounting; Actins; Affinity; Antibodies; Apoptosis; Back; Binding; Brain; Cell Line; Cell Proliferation; Cell physiology; Cells; Cytoskeleton; Development; Disease; ERM protein; Enhancers; Family; Future; Goals; Growth; Guanosine Triphosphate Phosphohydrolases; Human; In Vitro; Intracellular Membranes; Knowledge; Lipid Binding; Lipids; Malignant Neoplasms; Mediating; Mediator of activation protein; Membrane Glycoproteins; Membrane Proteins; Metabolism; Molecular; Molecular Conformation; Neoplasm Metastasis; Neurilemmoma; Neurofibromin 2; Oncogenic; Patients; Pharmaceutical Preparations; Phosphatidylinositols; Phosphorylation; Phosphorylation Site; Phosphotransferases; Physiological; Play; Proteins; RNA Interference; Regulation; Research; Research Personnel; Role; Second Messenger Systems; Signal Pathway; Testing; Tissues; Tumor Suppressor Genes; Tumor Suppressor Proteins; angiogenesis; base; cell motility; feeding; in vivo; insight; knock-down; link protein; mutant; novel; programs; research study; second messenger; tumor; tumorigenic

DESCRIPTION (provided by applicant): The NF2 tumor suppressor gene encodes an intracellular membrane-associated protein, called merlin or schwannomin, which belongs to the band 4.1 family (ERM proteins) of cytoskeleton-associated proteins that link cell surface glycoproteins to the actin cytoskeleton. Merlin growth suppression is dependent on its ability to form a productive N-term/C-term association. Merlin exists in "open" (inactive form) and "closed" (active growth suppressive form) conformations, which are regulated by an intramolecular association between the N- and C-termini of the protein. Numerous studies demonstrate that merlin phosphorylation plays an essential role in dictating its conformation and binding activity. Recently, we showed that wild-type merlin, but not patient-derived mutant (L64P), selectively binds PIKE-L and inhibits Phosphoinositol 3-kinase (PI 3- kinase) activity. PIKE (PI 3-Kinase Enhancer) is a brain-specific GTPase that binds to PI 3-kinase and stimulates its lipid kinase activity. This suppression of PI 3-kinase activity results from merlin disrupting the binding of PIKE-L to PI 3-kinase. Induction of merlin substantially diminishes PI 3-kinase/Akt signaling pathway in Schwannoma cells. Phosphorylation and phosphoinositol lipids binding coordinately mediate the activation of ERM proteins. However, whether Akt phosphorylates merlin and phosphoinositol lipids bind to merlin also control merlin activity remains elusive. We hypothesize that merlin is physiologically regulated by a negative feed-back mechanism of PI 3-kinase/Akt cascade. Specifically, we will test whether Akt phosphorylates merlin and modulates its conformation and subcellular localization. In addition, we will determine whether Akt phosphorylation and PI (3, 4, and 5) P3 synergistically mediate merlin's binding activity to the critical downstream effectors, resulting in abolishing merlin's tumor suppressive activity. Identification of signaling pathways mediating merlin phosphorylation and binding activity is essential not only for understanding the physiological functions of merlin, but also for the future development of novel drug treatments for this disease.

描述（由申请人提供）：NF2肿瘤抑制基因编码一种细胞内膜相关蛋白，称为merlin或schwannomin，属于细胞骨架相关蛋白的带4.1家族（ERM蛋白），将细胞表面糖蛋白与肌动蛋白细胞骨架连接起来。 Merlin 生长抑制取决于其形成有效的 N 端/C 端关联的能力。 Merlin 以“开放”（非活性形式）和“封闭”（活性生长抑制形式）构象存在，这些构象由蛋白质 N 端和 C 端之间的分子内缔合调节。大量研究表明，merlin 磷酸化在决定其构象和结合​​活性方面发挥着重要作用。最近，我们发现野生型 merlin（而非患者来源的突变体 (L64P)）选择性结合 PIKE-L 并抑制磷酸肌醇 3-激酶（PI 3-激酶）活性。 PIKE（PI 3-激酶增强剂）是一种大脑特异性 GTP 酶，可与 PI 3-激酶结合并刺激其脂质激酶活性。这种对 PI 3-激酶活性的抑制是由于 merlin 破坏了 PIKE-L 与 PI 3-激酶的结合。 merlin 的诱导显着减弱神经鞘瘤细胞中的 PI 3-激酶/Akt 信号通路。磷酸化和磷酸肌醇脂质结合协同介导 ERM 蛋白的激活。然而，Akt 磷酸化 merlin 以及与 merlin 结合的磷酸肌醇脂质是否也控制 merlin 活性仍不清楚。我们假设 merlin 在生理上受到 PI 3-激酶/Akt 级联的负反馈机制的调节。具体来说，我们将测试 Akt 是否磷酸化 merlin 并调节其构象和亚细胞定位。此外，我们将确定 Akt 磷酸化和 PI (3、4 和 5) P3 是否协同介导 merlin 与关键下游效应子的结合活性，从而消除 merlin 的肿瘤抑制活性。鉴定介导 merlin 磷酸化和结合活性的信号通路不仅对于了解 merlin 的生理功能至关重要，而且对于未来开发治疗该疾病的新药物也至关重要。