Schwann cell morphology and function in peripheral nerve regeneration

描述(申请人提供)：周围神经受损后，许多患者由于神经再生不足而遭受持续性疼痛或运动障碍。为了开发促进神经再生的新疗法，必须了解推动这一过程的细胞和分子机制。许多研究都集中在神经再生所涉及的神经元内源性信号，然而周围细胞类型，如神经胶质细胞，在促进轴突再生方面也起着重要作用。雪旺细胞是周围神经系统的主要神经胶质细胞，对轴突的维持和再生至关重要。损伤后，雪旺细胞去分化为不成熟状态，促进轴突再生和神经修复。雪旺细胞的去分化过程伴随着细胞的剧烈形态变化和迁移。然而，这些形态变化究竟是如何由细胞内事件驱动的，如细胞骨架重排和通过细胞内转运的膜重塑，目前仍不清楚。除行为改变外，去分化雪旺细胞还为再生轴突提供生长因子，并提供定向指导，允许轴突沿着正确的路径再生。然而，雪旺细胞用来指导轴突再生的特定引导分子尚不清楚。我们实验室的最新数据表明，在结直肠癌(DCC)中缺失的经典轴突引导受体突变与缺乏雪旺细胞的突变类似，显示出被误导的轴突再生。这表明DCC可能 在引导轴突再生方面发挥重要作用，可能是以雪旺细胞依赖的方式。在这里，我建议定义雪旺细胞促进轴突再生的细胞和分子机制。首先，我将使用活细胞成像来确定雪旺细胞的细胞骨架结构和细胞内运输是如何变化的 神经损伤。此外，我将通过对动力蛋白突变体的细胞类型特异性拯救来确定神经再生过程中Schwan细胞是否需要细胞内转运，该突变体具有显著的轴突再生缺陷。接下来，我将确定DCC是如何促进定向轴突再生的。使用活细胞成像，我将监测轴突生长锥体的行为 在神经切断后野生型和DCC突变体中同时存在雪旺细胞。此外，我将确定在哪种细胞类型(S)的DCC需要通过特定细胞类型的DCC突变再生的拯救来指导轴突再生。结合起来，拟议的实验将提供雪旺细胞促进体内神经再生的细胞和分子机制。

DESCRIPTION (provided by applicant): Following damage to peripheral nerves, many patients suffer from persistent pain or motor impairments due to inadequate nerve regeneration. In order to develop new therapies to promote nerve regeneration, it is imperative to understand the cellular and molecular mechanisms that drive this process. Many studies have focused on the neuron-intrinsic cues involved in nerve regeneration, however surrounding cell types, such as glial cells, also play an important role in promoting axonal regrowth. Schwann cells are the main glia of the peripheral nervous system and are critical for axonal maintenance and regeneration. Following injury, Schwann cells dedifferentiate to an immature state that promotes axonal regrowth and nerve repair. The process of Schwann cell dedifferentiation is accompanied by drastic morphological changes as well as cell migration. However, exactly how these morphological changes are driven by intracellular events, such as cytoskeletal rearrangements and membrane remodeling via intracellular transport, remains unknown. In addition to behavioral changes, dedifferentiated Schwann cells provide growth factors to regrowing axons and provide directional guidance, allowing axons to regrow along the proper path. The specific guidance molecules that are used by Schwann cells to direct axonal regrowth, however, are unknown. Recent data from our lab demonstrates that mutants for the classical axon guidance receptor, Deleted in Colorectal Carcinoma (DCC), show misguided axonal regrowth similar to that of mutants lacking Schwann cells. This suggests that DCC may play an important role in guiding axonal regrowth, potentially in a Schwann cell-dependent manner. Here, I propose to define the cellular and molecular mechanisms by which Schwann cells promote axonal regrowth. First, I will use live cell imaging to determine how cytoskeletal structure and intracellular transport change in Schwann cells in response to nerve injury. Additionally, I will determine whether intracellular transport is required in Schwan cells during nerve regeneration using cell-type specific rescue of a dynein mutant, which has significant axonal regeneration defects. Next, I will determine how DCC promotes directional axonal regrowth. Using live cell imaging, I will monitor the behavior of axonal growth cones and Schwann cells simultaneously in wild type and DCC mutants following nerve transection. Additionally, I will determine in which cell type(s) DCC is required to direct axonal regrowth using cell-type specific rescue of DCC mutant regeneration. Combined, the proposed experiments will provide cellular and molecular mechanisms by which Schwann cells promote nerve regeneration in vivo.