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

1）胶质细胞中LIS 1的表达：我们用免疫组化方法研究了LIS 1在胶质细胞中的表达。在大鼠脑中，星形胶质细胞谱系的细胞表达LIS 1以及神经元细胞。在人脑胶质瘤组织中，LIS 1在各种类型的胶质瘤中均有表达，与组织学类型和间变性程度无关。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显示出强烈的LIS 1表达。免疫组化结果显示，动力蛋白、dynactin、NudE/NudEL和NudC的表达模式相似，提示LIS 1及其相关蛋白在胶质细胞的迁移和分裂中起重要作用。2）显性负性LIS 1过表达的表型效应我们亚克隆了一株过表达显性负性LIS 1的C6胶质瘤细胞系（C6-LIS 1 N）。在C6-LIS 1 N细胞中，细胞极性明显丧失，迁移明显受到抑制。然而，它们能够分裂，表明LIS 1在细胞迁移和有丝分裂中的功能不同。3）显性负性LIS 1逆转录病毒载体我们构建了显性负性LIS 1编码逆转录病毒载体，并将其体内注射到出生后早期大鼠的脑室下区。与对照逆转录病毒感染的胶质祖细胞相比，胶质祖细胞的数量增加显示多极形态，并且它们的迁移被显著抑制。然而，细胞分裂，而激活显性负LIS 1逆转录病毒感染。这再次表明细胞的迁移和分裂是由LIS 1独立调控的。总之，我们已经证明LIS 1在神经胶质细胞和神经元细胞中表达。LIS 1可能在细胞迁移和分裂中独立调节微管功能。这些发现为了解无脑畸形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.