GAP JUNCTIONS AND SCHWANN CELLS

这些研究的总体目标是确定雪旺细胞的作用 缝隙连接在周围神经发育和再生中的作用 初步的假设是成熟的髓鞘雪旺细胞表达 缝隙连接蛋白Cx32以反射性接触的形式存在于 单细胞旁结部切牙和Schmidt-Lantermann切牙 发育早期和远端雪旺细胞的增殖 神经损伤中表达另一种缝隙连接蛋白(被鉴定为 Cx46)提供细胞间耦合功能以协调 成熟和对伤害的反应。因为Cx32中的点突变是 X连锁的Charcot-Marie Tooth综合征 (CMTX)，一种脱髓鞘的周围神经病，我们将相关变化 Cx32在体内髓鞘形成和正常培养中的表达 动物，我们将把这些发现与雪旺细胞的研究进行比较 Cx32和Cx46基因敲除动物的成熟和再髓鞘形成。因为 Cx46的表达和细胞增殖表型的诱导 雪旺细胞所致的神经损伤，我们将考察其时间进程 神经损伤后和再生过程中的变化。 拟议的研究将在体外和体内定义： 1)雪旺细胞在不同发育阶段表达的连接蛋白 成熟； 2)外周神经间隙连接蛋白表达的变化 损伤后和再髓鞘形成期间； 3)神经损伤过程中和损伤后有丝分裂原释放的影响 对培养雪旺细胞缝隙连接表达和功能的影响 4)细胞间隙连接蛋白表达改变对细胞增殖和增殖的影响 雪旺细胞在培养和神经中的分化反应。 总之，本申请中提出的基础广泛的研究应该 极大地扩展了我们对雪旺细胞细胞生物学的了解 它在病理条件下的调节。

The overall goal of these studies is to define the role of Schwann cell gap junctions in the development and regeneration of peripheral nerve. The primary hypothesis is that mature myelinating Schwann cells express the gap junction protein Cx32 in the form of reflexive contacts between paranodal and Schmidt-Lantermann incisures of single cell, whereas proliferating Schwann cells in early development and distal to the site of nerve injury express another gap junction protein (identified as Cx46) that provides intercellular coupling functioning to coordinate maturation and response to injury. Because point mutations in Cx32 are responsible for the X-Linked form of Charcot-Marie Tooth syndrome (CMTX), a demyelinating peripheral neuropathy, we will correlate changes in Cx32 expression with myelination in vivo and in culture in normal animals and we will compare these findings with studies of Schwann cell maturation and remyelination in Cx32 and Cx46 knockout animals. Because expression of Cx46 and the proliferating phenotype are induced in Schwann cells by nerve injury, we will examine the time course of changes after nerve injury and during regeneration. The proposed studies will define both in vitro and in vivo: 1) The connexins expressed by Schwann cells at specific stages of maturation; 2) The changes in connexin expression that occur in peripheral nerve following injury and during remyelination; 3) The effects of mitogens released during and following nerve injury on gap junction expression and function in cultured Schwann cells; and 4) The effects of altered connexin expression on proliferative and differentiation responses of Schwann cells in culture and in nerve. Together, the broadly based studies proposed in this application should greatly extend our knowledge of the cell biology of the Schwann cell and its modulation in pathological conditions.