Role of LIS1 in cell division and migration of neural progenitors and its relevance to lissencephaly

1)小细胞中LIS1的表达。我们用免疫组织化学方法研究了LIS1在神经胶质细胞中的表达。在大鼠脑中，星形细胞谱系的细胞和神经元细胞都表达LIS1。在人胶质瘤组织中，LIS1在各种类型的胶质瘤中均有表达，与组织学类型和间变程度无关。值得注意的是，一些正在进行有丝分裂的胶质瘤细胞和浸润周围脑实质的胶质瘤细胞表现出强烈的LIS1表达。免疫组化观察到dynein、dynactin、NudE/NudEL和NudC的表达模式相似，提示LIS1及其相关蛋白在胶质细胞的迁移和分裂中起重要作用。2)显性阴性LIS1过表达的表型效应我们亚克隆了一个过表达显性阴性LIS1的C6胶质瘤细胞系（C6- lis1n）。在C6-LIS1N细胞中，细胞极性明显丧失，迁移受到明显抑制。然而，它们能够分裂，这表明LIS1在细胞迁移和有丝分裂中的功能不同。3) LIS1显性阴性逆转录病毒载体我们制备了LIS1显性阴性编码逆转录病毒载体，并将其体内注射到产后早期大鼠心室下区。与对照组相比，感染逆转录病毒的神经胶质祖细胞数量增加，呈现多极形态，其迁移受到显著抑制。然而，显性阴性的LIS1逆转录病毒感染激活了细胞分裂。这再次表明细胞的迁移和分裂是由LIS1独立调控的。综上所述，我们已经证明LIS1在神经细胞和神经胶质细胞中都有表达。LIS1可能在细胞迁移和分裂过程中独立调控微管功能。这些发现为理解无脑脑的组织发生提供了基础。

1)LIS1 expression in gial cells.We have immunohistochemically investigated LIS1 expression in glial cells. In the rat brain, cells in astrocytic lineage expressed LIS1 as well as neuronal cells. In human glioma tissues, LIS1 was expressed in various types of glioma, regardless of histological type and the degree of anaplasia. Of note, some of the glioma cells undergoing mitosis and those infiltrating the surrounding brain parenchyma showed strong LIS1 expression. Comparable expression pattern was observed in immunohistochemistry for dynein, dynactin, NudE/NudEL and NudC, suggesting that LIS1, together with its associating proteins, play a significant role in migration and division of glial cells.2)Phenotypic effects of overexpression of dominant-negative LIS1We have subcloned a C6 glioma cell line overexpressing dominant-negative LIS1 (C6-LIS1N). In C6-LIS1N cells, cell polarity was significantly lost and migration was dramatically inhibited. However, they were capable of divide, indicating that LIS1 function differently in cell migration and mitosis.3)Dominant-negative LIS1 retrovirus vectorWe have generated dominant-negative LIS1 encoding retrovirus vector and injected in vivo into the subventricular zone of the early postnatal rat. Increased number of glial progenitors showed multipolar morphology compared to those infected with control retrovirus and their migration was dramatically inhibited. However, cell division was rather activated by dominant-negative LIS1 retrovirus infection. This again indicates cell migration and division are independently regulated by LIS1.In summary, we have demonstrated that LIS1 is expressed in cells in glial lineage as well as neuronal cells. LIS1 is likely to regulate microtubule function independently in cell migration and division. These findings provides a foundation for understanding the histogenesis of lissencephalic brains.