Myotubularin PI 3-Phosphatases as Regulators of Peripheral Nerve Myelination

肌管蛋白 PI 3-磷酸酶作为周围神经髓鞘形成的调节剂

基本信息

批准号：
9252598
负责人：
FRED L ROBINSON
金额：
$ 33.69万
依托单位：
OREGON HEALTH & SCIENCE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-04-15 至 2019-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9252598
关键词：
1-Phosphatidylinositol 4-Kinase Affect Back Binding Biochemical Cell Survival Cell division Cell membrane Charcot-Marie-Tooth Disease Coculture Techniques Code Complex Defect Deposition Disease Endocytosis Eukaryota Family Generations Genetically Engineered Mouse Goals Guanine Nucleotide Exchange Factors Guanosine Triphosphate Phosphohydrolases High Pressure Liquid Chromatography Homeostasis Hydrolysis In Vitro Inherited Knockout Mice Lead Limb structure Lipids Location MADD gene Mediating Membrane Membrane Protein Traffic Membrane Proteins Metabolism Modeling Morphology Mutation Myelin Myelin Sheath Organelles Output Pathway interactions Patients Peripheral Nerves Peripheral Nervous System Diseases Pharmacology Phosphatidylinositols Phospholipase Phosphoric Monoester Hydrolases Phosphotransferases Protein Isoforms Proteins Recruitment Activity Recycling Regulation Research Role Scaffolding Protein Schwann Cells Sensory Signal Transduction Signaling Molecule Tertiary Protein Structure Testing Therapeutic Transmembrane Transport Type 4b Charcot Marie Tooth Disease United States axonal degeneration base cell growth cell motility disease-causing mutation effective therapy human disease knockout gene loss of function mutation member muscle degeneration myelination myotubularin nervous system disorder novel phosphatidylinositol 3,5-diphosphate phosphatidylinositol 3-phosphate phosphoinositide 3-phosphate public health relevance rab GTP-Binding Proteins scaffold trafficking

项目摘要

DESCRIPTION (provided by applicant): The overall goal of the proposed research is to determine the mechanisms by which disturbances in phosphoinositide (PI) regulation lead to abnormal membrane trafficking and cellular signaling in myelinating Schwann cells. We are studying this question in the context of a specific form of demyelinating Charcot-Marie-Tooth peripheral neuropathy (type 4B~ CMT4B), which is characterized by abnormal myelination and severe axonal degeneration. CMT is one of the most common inherited neurological disorders, affecting about 1 in 2500 worldwide. This condition leads to progressive degeneration of the muscles of the extremities and loss of sensory function. CMT4B is caused by loss of function mutations in either myotubularin-related protein 2 (MTMR2) or MTMR13, which belong to a large family of phosphatases that act as key regulators of PI signaling. MTMR2 is a PI 3-phosphatase that specifically dephosphorylates phosphatidylinositol 3-phosphate (PI3P) and phosphatidylinositol 3,5-bisphosphate (PI[3,5]P2). PI3P and PI(3,5)P2 regulate membrane traffic within the endosomal/lysosomal pathway. Therefore, it is theorized that CMT4B arises from defects in membrane transport in Schwann cells. MTMR13 is a catalytically inactive "pseudophosphatase" that associates directly with MTMR2. MTMR13 appears to function as a scaffold protein that regulates MTMR2. The first aim of this proposal is to define the phosphoinositide kinase-phosphatase network that controls PI3P and PI(3,5)P2 regulation in Schwann cells. The impact of the loss of PI kinases and phosphatases on phosphoinositide levels will be evaluated using HPLC-based phosphoinositide profiling. In parallel, the impact of the loss of PI kinases and phosphatases on myelination will be assessed using in vitro myelinating cultures and morphological examination of peripheral nerves of knockout mice. The second aim of the study is to define the function of the Mtmr13 pseudophosphatase in Schwann cell membrane traffic by determining how Mtmr13's activation of Rab GTPases regulates myelination, and by assessing the role of the Mtmr2-Mtmr13 complex in the regulation of endocytosis. These goals will be accomplished using biochemical studies to identify interacting Rab GTPases, as well as in vitro myelinating co-cultures to assess the relevance of specific interactions to myelination. The final aim of this proposal is to determine which domains of Mtmr13 control its specific functions. Collectively, these studies will allow us to define the specific, critical roles of phosphoinositides in myelinating Schwann cells. These studies also may well form the basis of a rational approach to the treatment of CMT4B by pharmacological targeting of the PI3P-PI(3,5)P2 pathway.

描述（由申请人提供）：拟议研究的总体目标是确定磷酸肌醇（PI）调节紊乱导致有髓鞘雪旺细胞膜运输和细胞信号传导异常的机制。我们正在一种特定形式的脱髓鞘性腓骨肌周围神经病（4B~CMT4B）的背景下研究这个问题，其特征是髓鞘形成异常和严重的轴突变性。 CMT 是最常见的遗传性神经系统疾病之一，影响全球约 2500 人中的 1 人。这种情况会导致四肢肌肉进行性退化和感觉功能丧失。 CMT4B 是由肌管蛋白相关蛋白 2 (MTMR2) 或 MTMR13 的功能缺失突变引起的，MTMR13 属于磷酸酶大家族，是 PI 信号传导的关键调节因子。 MTMR2 是一种 PI 3-磷酸酶，可特异性地使磷脂酰肌醇 3-磷酸 (PI3P) 和磷脂酰肌醇 3,5-二磷酸 (PI[3,5]P2) 去磷酸化。 PI3P 和 PI(3,5)P2 调节内体/溶酶体途径内的膜运输。因此，推测 CMT4B 是由雪旺细胞膜运输缺陷引起的。 MTMR13 是一种无催化活性的“假磷酸酶”，与 MTMR2 直接结合。 MTMR13 似乎充当调节 MTMR2 的支架蛋白。该提案的第一个目的是定义控制雪旺细胞中 PI3P 和 PI(3,5)P2 调节的磷酸肌醇激酶-磷酸酶网络。 PI 激酶和磷酸酶损失对磷酸肌醇水平的影响将使用基于 HPLC 的磷酸肌醇分析进行评估。同时，将使用体外髓鞘培养和基因敲除小鼠周围神经的形态学检查来评估 PI 激酶和磷酸酶的丧失对髓鞘形成的影响。该研究的第二个目的是通过确定 Mtmr13 激活 Rab GTPases 如何调节髓鞘形成以及评估 Mtmr2-Mtmr13 复合物在内吞作用调节中的作用来确定 Mtmr13 假磷酸酶在雪旺细胞膜运输中的功能。这些目标将通过生化研究来识别相互作用的 Rab GTPases，以及体外髓鞘共培养来评估特定相互作用与髓鞘形成的相关性来实现。该提案的最终目的是确定 Mtmr13 的哪些域控制其特定功能。总的来说，这些研究将使我们能够确定磷酸肌醇在髓鞘化雪旺细胞中的具体、关键作用。这些研究也很可能构成通过药物靶向 PI3P-PI(3,5)P2 途径治疗 CMT4B 的合理方法的基础。