Connexin abnormality in perpharal hervons system dicease

Connexin32 （Cx32）是一种间隙连接蛋白，其基因突变是导致x连锁沙克-玛丽-图斯病的原因。我们检测了转染突变（C53S和Pl72R） Cx32基因的C6胶质瘤细胞的功能异常。未转染的C6胶质瘤细胞不表达Cx32 mRNA或蛋白。Northern和Western blot分析显示，在转染了野生型基因和突变型Cx32基因的细胞中，Cx32 mRNA和蛋白均有表达。对携带野生型基因的细胞的免疫细胞化学研究表明，Cx32存在于细胞膜和细胞质中。在转染C53S或P172R突变基因的细胞中，细胞膜未发现免疫反应性。刮片加载和染料转移方法在野生型细胞中产生了有效的染料转移，而在突变型细胞中则没有。细胞增殖试验显示，未转染细胞、转染野生型基因的细胞和转染突变基因的细胞之间没有差异。髓磷脂蛋白的信使RNA表达在这些细胞中没有变化。这些发现表明，Cx32基因突变导致细胞间通信的丧失，因为Cx32蛋白无法整合到形成间隙连接的细胞膜中。然而，至少在C6胶质瘤细胞中，突变不会干扰细胞增殖或髓磷脂特异性基因表达。用背根神经节神经元培养的雪旺细胞检测Cx32 mRNA和蛋白的表达。Cx32 mRNA和蛋白在培养1周后出现，髓鞘碱性蛋白和Po蛋白在培养2天后出现。Cx32的功能似乎是维持髓磷脂膜而不是形成髓磷脂。

Connexin32 (Cx32) is a gap junction protein and its gene mutations are responsible for X-linked Charcot-Marie-Tooth disease. We examined the functional abnormality of C6 glioma cells transfected with mutant (C53S and Pl72R) Cx32 genes. Nontransfected C6 glioma cells did not express Cx32 mRNA or protein. Northern and Western blot analyzes showed Cx32 mRNA and protein in cells transfected with the wild-type gene as well as with the mutant Cx32 genes. An immunocytochemical study of cells with the wild-type gene showed that Cx32 is present in the cell membrane and cytoplasm. In cells transfected with C53S or P172R mutant gene, however, no immunoreactivity was found in the cell membrane. The scrape-loading and dye transfer method produced effective dye transfer in cells with the wild-type gene but not in those with mutant genes. A cell proliferation assay showed no differences in nontransfected cells, cells transfected with the wild-type gene and those with the mutant genes. Messenger RNA expression for myelin proteolipid protein did not change in any of these cells. These findings suggest that Cx32 gene mutation results in loss of cell-to-cell communication because of failure to incorporate Cx32 protein in the cell membrane where gap junctions are formed. The mutations do not, however, interfere with cell proliferation or myelin-specific gene expression, at least in C6 glioma cells.Cx32 mRNA and protein expression was examined using Schwann cells cultured with dorsal root ganglion neurons. The apparance of Cx32 mRNA and protein was I week after the start of culture whereas those of myelin basic protein and Po protein were 2 days after the start. The function of Cx32 appears to maintain the myelin membrane rather than to form myelin.