Molecular Mechanisms That Control Neuronal Positioning D

大脑发育不正常会导致婴儿期或以后出现明显的神经系统疾病。遗传和环境因素都会影响大脑形成的许多方面，这些方面需要神经元的正确规范、定位和连接。我们感兴趣的是在发育过程中调节神经元位置的遗传因素，以及这些基因在成年期可能发挥的作用。已经解决了一个分子级联，包括分泌配体，Reln，细胞表面受体，LDLR和ApoER2，以及细胞质接头分子Dab1，它们是发育过程中适当的神经元放置所必需的。我们之前已经证明Dab1在胚胎神经元的Reln刺激下被酪氨酸磷酸化；Dab1酪氨酸磷酸化位点是正常大脑结构发育所必需的。我们目前正在培养个体磷酸化位点突变的小鼠，以确定对Reln的部分反应的后果。我们假设，每个磷酸化位点可能通过促进Dab1和信号伙伴之间的蛋白-蛋白相互作用，激活一个谨慎的下游通路，控制神经元对Reln的不同反应。我们还通过酵母双杂交筛选和生化亲和纯化，以磷酸酪氨酸依赖的方式鉴定与Dab1相互作用的分子。我们已经确定了一些相互作用的分子，我们正在分析与Reln信号通路的生理相关性。为了解决Reln-Dab1信号转导通路在成人神经系统中所起的作用，我们生成了一个Dab1的条件等位基因。我们计划在成年神经元的一个亚群（如小脑浦肯野细胞）中灭活该等位基因，以检测出生后Dab1功能丧失可能导致的神经功能障碍。

Improper brain development can lead to neurological disorders apparent during infancy or later in life. Both genetic and environmental factors influence the many aspects of brain formation that require the correct specification, positioning, and connection of neurons. We are interested in the genetic factors that regulate neuronal placement during development, in addition to the role these genes may play in adulthood. A molecular cascade has been resolved that includes a secreted ligand, Reln, cell surface receptors, LDLR and ApoER2, and a cytoplasmic adaptor molecule, Dab1, which are required for appropriate neuronal placement during development. We have previously shown that Dab1 is tyrosine phosphorylated in response to Reln stimulation of embryonic neurons; Dab1 tyrosine phosphorylation sites are requisite for normal brain structure development. We are currently generating mice with mutations in individual phosphorylation sites to determine the consequences of a partial response to Reln. We hypothesize that each phosphorylation site may activate a discreet downstream pathway that controls different aspects of the neuronal response to Reln, by promoting protein-protein interactions between Dab1 and signaling partners. We are also engaged in the identification of molecules that interact with Dab1 in a phosphotyrosine dependent manner, by both yeast two hybrid screens and biochemical affinity purification. We have identified a number of interacting molecules that we are analyzing for physiological relevance to the Reln signaling pathway. To address the role the Reln-Dab1 signal transduction pathway plays in the adult nervous system, we have generated a conditional allele of Dab1. We plan to inactivate this allele in a subset of adult neurons, such as cerebellar Purkinje cells, to assay for neurological dysfunction that may result from postnatal loss of Dab1 function.