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: 7392829
• 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/7392829
• 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

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 suppressiveform) 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 (3,4,5)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.

NF2肿瘤抑制基因编码细胞内膜相关蛋白，称为Merlin或 Schwannomin，属于细胞骨架相关蛋白的Band 4.1家族（ERM蛋白） 将细胞表面糖蛋白与肌动蛋白细胞骨架联系起来。梅林的增长抑制取决于其能力 形成生产性的N-期限/C期协会。 Merlin以“开放”（非活动形式）和“关闭”（活动）存在 生长抑制形构象，由分子内关联调节 蛋白质的N-和C末端。大量研究表明，梅林磷酸化作用 在决定其构象和结合​​活性中的重要作用。最近，我们表明野生型梅林， 但不是患者衍生的突变体（L64p），有选择地结合派克-L并抑制磷酸肌醇3-激酶（PI 3-- 激酶）活性。派克（PI 3-激酶增强剂）是一种与PI 3-激酶结合的脑特异性GTPase 刺激其脂质激酶活性。 Pi 3-激酶活性的这种抑制是由于Merlin破坏了 派克-L与PI 3-激酶的结合。 Merlin的诱导大大减少了PI 3-激酶/AKT信号传导 切旺纳马瘤细胞中的途径。磷酸化和磷酸肌醇脂质结合协同介导 ERM蛋白的激活。但是，AKT是否磷酸化Merlin和磷酸肌醇脂质与 梅林还控制梅林活动仍然难以捉摸。我们假设Merlin在生理上受到 PI 3-激酶/AKT级联的负馈回机制。具体来说，我们将测试是否akt 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（3,4,5）P3是否协同介导Merlin的结合活性与 关键的下游效应子，导致消除了梅林的肿瘤抑制活性。识别 介导merlin磷酸化和结合活性的信号通路不仅对 了解梅林的生理功能，也了解新药物的未来发展 治疗这种疾病。