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。 主要假设是成熟的髓鞘化雪旺细胞表达 差距连接蛋白Cx 32以反射接触的形式存在于 结旁和Schmidt-Lantermann切口的单细胞，而 在早期发育和远端部位增殖的雪旺细胞 表达另一种间隙连接蛋白（鉴定为 Cx46），提供细胞间偶联功能， 成熟和对损伤的反应。因为Cx 32的点突变 导致X连锁型腓骨肌萎缩症 （CMTX），脱髓鞘性周围神经病变，我们将相关的变化 Cx 32表达与髓鞘形成在体内和在正常 动物，我们将比较这些发现与雪旺细胞的研究， Cx 32和Cx46敲除动物的成熟和髓鞘再生。因为 Cx46的表达和增殖表型被诱导， 雪旺细胞的神经损伤，我们将检查的时间过程中， 神经损伤后和再生过程中的变化。 拟定研究将定义体外和体内： 1)雪旺氏细胞在不同发育阶段表达的连接蛋白 成熟; 2)周围神经连接蛋白表达的变化 损伤后和髓鞘再生期间; 3)神经损伤时和损伤后释放的促分裂素的作用 对培养的雪旺细胞中间隙连接表达和功能的影响;以及 4)连接蛋白表达改变对细胞增殖和凋亡的影响 培养和神经中的雪旺细胞的分化反应。 总之，本申请中提出的基础广泛的研究应 大大扩展了我们对雪旺细胞的细胞生物学知识， 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.