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ANALYSIS OF MOLECULAR MECHANISMS UNDERLYING CORTICAL ALIGNMENT

皮质排列的分子机制分析

基本信息

批准号：
10480213
负责人：
OGAWA Masaharu
金额：
$ 7.62万
依托单位：
INSTITUTE FOR PHYSICAL AND CHEMICAL RESEARCH (RIKEN) (1999-2000)Kochi Medical School (1998)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

The present research aim is to provide better understanding the cellular and molecular mechanisms of cortical development, especially the interplay of reelin signal cascade with cortical cell's alignment. In the neurological mutant mice reeler, the various classes of cortical neurons are generated and complete their migration at the normal time, however, the cellular pattern in the radial dimension is distorted, i.e., the cortical lamination is roughly inverted. We showed experimentally that Reelin, the product of the reeler gene (Reln) and secreted from the Cajal-Retzius cells, provides an instructive signal for migrating cortical neurons to align at appropriate location ill developing cortex. Using a unique antibody CR-50 which recognizes Reelin, we showed that Reelin binds each other to form a huge protein complex and suggested that this assembly formation is critical for its function. The reeler phenotype is also observed in yotari mutant mice lacking the mdab1 gene which encodes s … More ignal transduction-associated protein Dab1. We have found that the yotari mutation is caused by a replacement of dab1 gene sequence with a long interspersed nuclear element (L1) fragment. Unlike Reelin, Dab1 is expressed in the cortical plate neurons, resides in the cytoplasm and interacts with tyrosine kinases of the Src family. In addition, phosphorylation of Dab1 is decreased in reeler, but increased when Reelin is added to cortical cell cultures. These observations indicated the presence of the Reelin receptors in the cell membrane of the cortical plate neurons that sense the extracellular Reelin, couple with tyrosine kinases and relay this signal to the cell via Dab1. Yagi group had previously showed that Fyntyrosine kinase has a crucial molecular function in building brain network and isolated a novel cadherin-related neuronal receptor (CNR) family proteins localized on the cell membrane of the cortical neurons using Fyn binding activity from the mouse brain. Collaborating with Yagi group, we identified a CNR family as a candidate of Reelin receptors. In addition to CNRs, two membrane proteins, apoER2 and VLDLR, have been identified as Reelan receptors. We provided antibodies against these receptor proteins and showed that extracellular Reelin proteins and these receptor proteins are co-localized on the processes of cortical plate neurons. We are now investigating how these receptors act in concert as components of the Reelin receptors. Less

本研究的目的是为了更好地了解皮质发育的细胞和分子机制，特别是Reelin信号级联与皮质细胞排列的相互作用。在神经学突变的小鼠卷轴上，在正常时间内产生了各种类型的皮质神经元并完成了它们的迁移，然而，细胞在径向的模式是扭曲的，即皮质层叠大致是颠倒的。我们的实验表明，Reelin是Reeler基因(Reln)的产物，由Cajal-Retzius细胞分泌，为迁移的皮质神经元提供了一个指导信号，使其在发育中的皮质中排列在适当的位置。使用识别Reelin的独特抗体CR-50，我们证明Reelin相互结合形成一个巨大的蛋白质复合体，并表明这种组装形成对其功能至关重要。在缺乏编码S…的mdab1基因的yotari突变小鼠中也观察到卷轴表型。更多的信号转导相关蛋白Dab1。我们发现，yotari突变是由于dab1基因序列被一个长的散布的核元件(L1)片段替换而引起的。与Reelin不同，Dab1在皮质板状神经元中表达，存在于细胞质中，并与Src家族的酪氨酸激酶相互作用。此外，在Reeler中，Dab1的磷酸化水平降低，但在皮质细胞培养中加入Reelin时，Dab1的磷酸化水平增加。这些观察表明，皮质板状神经元的细胞膜上存在Reelin受体，它可以感知细胞外的Reelin，与酪氨酸激酶偶联，并通过Dab1将该信号传递给细胞。Yagi小组先前已经证明Fyntyroine Kinase在构建脑网络中具有重要的分子功能，并利用Fyn结合活性从小鼠脑中分离到一个定位于皮质神经元细胞膜上的新的钙粘素相关神经元受体(CNR)家族蛋白。与Yagi小组合作，我们确定了一个CNR家族作为Reelin受体的候选者。除CNRs外，ApoER2和VLDLR两种膜蛋白也被鉴定为Reelan受体。我们提供了针对这些受体蛋白的抗体，并表明细胞外Reelin蛋白和这些受体蛋白共同定位于皮质板状神经元的突起。我们现在正在研究这些受体是如何作为Reelin受体的组成部分协同工作的。较少