Identification of Novel Drug Targets For Use in Preventing Deafness Caused by NF2

鉴定用于预防 NF2 引起的耳聋的新药物靶点

• 批准号: 7699548
• 负责人: CRISTINA Maria FERNANDEZ-VALLE
• 金额: $ 29.6万
• 依托单位: UNIVERSITY OF CENTRAL FLORIDA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7699548
• 关键词: Acoustic Nerve; Acoustic Neuroma; Actins; Adult; Apoptosis; Auditory Brain Stem Implants; Autocrine Communication; Axon; Basal lamina; Binding; Brain Stem; Cancer Biology; Cell Death; Cell Shape; Cell membrane; Cell physiology; Cell-Cell Adhesion; Cells; Cellular Morphology; Complete Hearing Loss; Complex; Cues; Cyclic AMP-Dependent Protein Kinases; Cytokinesis; Cytoskeleton; Defect; Development; Disease; Drug Delivery Systems; Effectiveness; Equilibrium; Excision; Facial paralysis; Genes; Goals; Growth; Hearing; Human; In Vitro; Individual; Integrins; Investigation; LIM Domain Kinase 1; Laminin; Life; Ligands; Link; Malignant Neoplasms; Measures; Membrane; Membrane Proteins; Mitotic spindle; Molecular; Monitor; Morphology; Mus; Mutate; Mutation; Nerve; Neuregulins; Neurilemmoma; Neurofibromatoses; Neurofibromatosis 2; Neurofibromin 2; Neurons; Operative Surgical Procedures; Orphan; Outcome; Pathogenesis; Pathway interactions; Patients; Peptides; Pharmaceutical Preparations; Pharmacological Treatment; Phenotype; Phosphorylation; Plasmids; Play; Positioning Attribute; Process; Proteins; Rattus; Reagent; Regulation; Reporting; Research Personnel; Risk; Role; Schwann Cells; Serine; Shapes; Signal Pathway; Signal Transduction; Signaling Protein; Site; Spinal Ganglia; Stream; Subfamily lentivirinae; Symptoms; Teenagers; Testing; Therapeutic; Tumor Suppressor Proteins; Virus; Work; bilateral acoustic schwannoma; bilateral vestibular Schwannoma; cell motility; cofilin; cofilin 2; deafness; density; effective therapy; experience; extracellular; genetic regulatory protein; hearing impairment; in vitro Model; irradiation; novel; novel therapeutics; p21 activated kinase; paxillin; polymerization; prevent; receptor; repaired; response; success; tumor; tumor growth

DESCRIPTION (provided by applicant): Neurofibromatosis type 2 (NF2) is a tumor disorder characterized by development of bilateral vestibular schwannomas also called acoustic neuromas. 98% of all NF2 patients experience partial to complete loss of hearing. Treatment for NF2 is balanced between monitoring tumor growth and the slow but progressive loss of hearing with surgical removal of larger tumors impinging on brainstem function and complete and permanent deafness. Cochlear and auditory brainstem implants have been used to partially restore hearing in a subset of patients with varying success. Therapeutics that slow or reverse tumor growth whilst maintaining hearing are currently lacking. This proposal tests the hypothesis that correcting the cytoskeletal defects in supernumerary schwannoma cells lacking function of the nf2 gene product, schwannomin/merlin, will allow these cells to interact with axons and receive cues promoting their differentiation and/or apoptosis. Identifying proteins that directly bind actin and regulate Schwann cell morphology is of the utmost importance. These proteins can serve as targets for drugs that will repair actin dynamics in schwannoma cells and restore axonal contact. Alternatively, drugs that modify actin regulatory proteins could promote cell death as a result of failed cytokinesis and mitotic spindle organization. One function of schwanomin/merlin is to inhibit Cdc42/Rac activation of p21 activated kinase (PAK). We will investigate LIM kinase (LIMK) and cofilin, terminal targets in a PAK signaling pathway. LIMK is a substrate for PAK, thus its activity is predicted to be high in schwannomas. Cofilin is a ubiquitously expressed actin-binding factor that depolymerizes f-actin and creates nucleation sites for new actin polymerization. Cofilin's function is inhibited by phosphorylation on serine-3 by LIMK. Our preliminary studies demonstrate that LIMK and cofilin modulate actin dynamics and function in Schwann cells. Moreover, our results suggest that LIMK and cofilin act down-stream of Schwannomin/merlin. We propose studies to: 1) identify the role of these proteins in controlling actin polymerization and cellular function in normal rat Schwann cells, 2) establish an in vitro model for NF2 using nf2ex2deleted mouse SCs to determine if inactivation of schwannomin/merlin leads to de-regulation of LIMK and cofilin activity and loss of SC function, and 3) determine if modulators of LIMK and cofilin restore the morphology and function of nf2ex2deleted SCs. These studies are initial steps in validating LIMK and/or cofilin as drug targets for development of an effective treatment for NF2 aimed at preserving hearing. The work in this proposal is relevant to the loss of hearing caused by Neurofibromatosis type 2. This disorder is characterized by development of bilateral acoustic schwannomas and loss of hearing in 98% of patients. As an outcome of this proposal, we hope to create a well characterized in vitro model for NF2 and advance a novel therapeutic direction, the actin modifying proteins LIMK and cofilin.

描述（由申请人提供）：2型神经纤维瘤病（NF2）是一种以双侧前庭神经鞘瘤（也称为听神经瘤）为特征的肿瘤疾病。98%的NF2患者部分或完全丧失听力。NF2的治疗在监测肿瘤生长和缓慢但渐进的听力丧失（通过手术切除影响脑干功能的较大肿瘤和完全性和永久性耳聋）之间取得平衡。人工耳蜗和听觉脑干植入物已被用于部分恢复患者的听力，取得了不同程度的成功。目前还缺乏在维持听力的同时减缓或逆转肿瘤生长的治疗方法。这一建议验证了一个假设，即纠正多余神经鞘瘤细胞缺乏nf2基因产物神经鞘蛋白/梅林功能的细胞骨架缺陷，将允许这些细胞与轴突相互作用，并接收促进其分化和/或凋亡的信号。确定直接结合肌动蛋白并调节雪旺细胞形态的蛋白是至关重要的。这些蛋白可以作为药物的靶点，修复神经鞘瘤细胞中的肌动蛋白动力学并恢复轴突接触。另外，修饰肌动蛋白调节蛋白的药物可能会由于细胞分裂和有丝分裂纺锤体组织失败而促进细胞死亡。schwanomin/merlin的一个功能是抑制p21活化激酶（PAK）的Cdc42/Rac活化。我们将研究LIM激酶（LIMK）和cofilin，它们是PAK信号通路的末端靶点。LIMK是PAK的底物，因此预计其活性在神经鞘瘤中较高。Cofilin是一种普遍表达的肌动蛋白结合因子，它可以解聚f-肌动蛋白，并为新的肌动蛋白聚合创造成核位点。LIMK对丝氨酸-3的磷酸化抑制了Cofilin的功能。我们的初步研究表明，LIMK和cofilin调节了雪旺细胞中肌动蛋白的动力学和功能。此外，我们的研究结果表明LIMK和cofilin在Schwannomin/merlin的下游起作用。我们拟开展以下研究：1)确定这些蛋白在正常大鼠雪旺细胞中控制肌动蛋白聚合和细胞功能中的作用；2)利用nf2ex2缺失的小鼠SCs建立NF2体外模型，以确定神经鞘蛋白/merlin失活是否导致LIMK和cofilin活性的失活以及SC功能的丧失；3)确定LIMK和cofilin的调节剂是否能恢复nf2ex2缺失的SC的形态和功能。这些研究是验证LIMK和/或cofilin作为开发NF2有效治疗以保护听力的药物靶点的初步步骤。本建议的工作与2型神经纤维瘤病引起的听力损失有关。这种疾病的特点是双侧听神经鞘瘤的发展和98%的患者听力丧失。作为这一提议的结果，我们希望建立一个具有良好特征的NF2体外模型，并提出一个新的治疗方向，即肌动蛋白修饰蛋白LIMK和cofilin。