Cell type-specific roles of calpain-2 in formation of peripheral myelinated nerves

项目摘要/摘要 雪旺细胞和神经元对于有髓神经纤维的形成是必不可少的。 周围神经系统(PNS)。除了髓鞘对轴突的电绝缘外，Schwann 细胞组装Ranvier的节点，这是快速有效的动作电位所需的可兴奋的轴突结构域 传播。此外，雪旺细胞积极调节三叉神经核的退化和再生。然而， 这些结构在疾病中如何形成、维持和破坏的细胞和分子机制 人们对这些情况仍然知之甚少。这一关键的知识差距限制了该领域操纵 雪旺细胞和神经元用于治疗三叉神经节疾病和损伤。本应用程序的总体目标是 目的是确定三叉神经节有髓神经形成和损伤过程中的关键分子机制。这个 以前的研究和这里提供的初步数据已经确定了钙依赖的钙调蛋白的激活。 细胞内的半胱氨酸蛋白酶和钙蛋白酶-2水平的升高参与了这些过程。这个 在小鼠中，Calain-2的结构性敲除导致在髓鞘形成之前的胚胎死亡，进一步 强调Calain-2在包括神经系统在内的多个器官发育中的重要性。这个 中心假说是Calain-2调节周围有髓神经的形成和损伤。开始，开始 验证这一假设，这一应用程序将产生在髓鞘形成过程中缺乏Calain-2的条件性基因敲除小鼠 雪旺细胞(目标1)或感觉神经元(目标2)。具体目标一将检验施旺的假设 细胞钙蛋白酶-2介导三叉神经节的髓鞘形成。具体目标二将检验轴突Calain-2的假设 调制Ranvier结构的PNS节点。三叉神经节的髓鞘和结节结构以及三叉神经节的神经传导 有髓轴突和动物行为将在出生后发育期间和成年条件下进行检查 敲除和控制小鼠。这个应用程序在概念上是创新的，因为我们提出CalPain-2是一种 PNS中有髓神经形成的关键调节因子。此应用程序将生成新的Calain-2条件性 基因敲除小鼠，将用于未来的研究，以确定雪旺细胞特异性或神经元特异性的作用 Calain-2在三叉神经节损伤修复中的作用。这项拟议的研究意义重大，因为完成这些目标将 确定Calain-2是三叉神经节中有髓神经形成和重塑的潜在调节剂。 此外，未来的研究，利用在这一应用中产生的条件基因敲除小鼠，有望 揭示Calain-2在三叉神经节损伤中的细胞类型特定作用，并将对未来的翻译产生重大影响 研究旨在开发针对各种三叉神经病和损伤的新疗法。

Project summary/abstract Both Schwann cells and neurons are essential for the formation of myelinated nerve fibers in the peripheral nervous system (PNS). In addition to the electrical insulation of axons by myelin sheaths, Schwann cells assemble nodes of Ranvier, the excitable axonal domains required for rapid and efficient action potential propagation. Furthermore, Schwann cells actively modulate PNS degeneration and regeneration. However, the cellular and molecular mechanisms of how these structures are formed, maintained, and disrupted in disease conditions remain poorly understood. This critical gap in knowledge limits the field’s ability to manipulate the Schwann cells and neurons for treatment of PNS diseases and injuries. The overall objective of this application is to identify a critical molecular mechanism in the process of PNS myelinated nerve formation and injury. The prior studies and preliminary data provided here have identified activation of calpains, calcium-dependent intracellular cysteine proteases, and elevation of calpain-2 levels are involved in these processes. The constitutive knockout of calpain-2 in mice results in embryonic lethality before myelin is formed, further emphasizing the importance of calpain-2 in development of multiple organs including nervous system. The central hypothesis is that calpain-2 modulates formation and injury of peripheral myelinated nerves. To begin to test this hypothesis, this application will generate conditional knockout mice lacking calpain-2 in myelinating Schwann cells (Aim 1) or in sensory neurons (Aim 2). Specific aim one will test the hypothesis that Schwann cell calpain-2 mediates PNS myelination. Specific aim two will test the hypothesis that axonal calpain-2 modulates PNS node of Ranvier structures. Myelin and nodal structures in PNS, nerve conduction along PNS myelinated axons, and animal behavior will be examined during postnatal development and in adult conditional knockout and control mice. This application is conceptually innovative, in that we propose that calpain-2 is a key modulator of myelinated nerve formation in PNS. This application will generate novel calpain-2 conditional knockout mice, which will be used in future studies to determine Schwann cell-specific or neuron-specific roles of calpain-2 in PNS injury and repair. The proposed research is significant, because completion of the aims will identify calpain-2 as a potential modulator of myelinated nerve formation and remodeling in the PNS. Furthermore, future research, utilizing conditional knockout mice generated in this application, is expected to uncover cell type-specific roles of calpain-2 in PNS injuries and will substantially impact future translational research aimed at the development of novel therapies for a wide variety of PNS diseases and injuries.