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

基本信息

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
项目类别：
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

项目摘要

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 肿瘤抑制基因编码一种细胞内膜相关蛋白，称为 merlin 或雪旺诺明，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的生长抑制取决于它的能力形成富有成效的 N 项/C 项关联。 Merlin 以“开放”（非活动形式）和“封闭”（活动形式）存在生长抑制形式）构象，这是由分子内关联调节的蛋白质的 N 端和 C 端。大量研究表明 merlin 磷酸化在在决定其构象和结合活性方面发挥着重要作用。最近，我们展示了野生型梅林，但不是患者来源的突变体 (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 PI 3-激酶/Akt 信号传导神经鞘瘤细胞中的通路。磷酸化和磷酸肌醇脂质结合协调介导 ERM 蛋白的激活。然而，Akt 是否磷酸化 merlin 和磷酸肌醇脂质 merlin 还控制 merlin 的活动仍然难以捉摸。我们假设 merlin 的生理调节作用是 PI 3-激酶/Akt级联的负反馈机制。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 (3,4,5)P3 是否协同介导 merlin 的结合活性关键的下游效应器，导致梅林的肿瘤抑制活性消失。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，也为未来新药的开发这种疾病的治疗方法。