Molecular basis of Zic proteins-mediated developmental regulation.

在这个研究项目中，我们调查了以下几个主题：1。调控Zic蛋白功能的信号转导通路的阐明。2.Zic蛋白转录因子激活域的鉴定。3.未鉴定的锌结合蛋白的鉴定。4.了解已鉴定的蛋白-蛋白相互作用的调控机制及其在发育调控中的意义。5.Zic蛋白下游靶基因的探索与分析。作为调查的成果，我们揭示了以下事实：Zic蛋白可以在物理和功能上与Gli蛋白相互作用，后者是Hedgehog信号的转录介质（Koyabu et al., 2001; Mizugishi et al., 2001）， 2。Zic1可以激活Notch信号，通过对鸡和小鼠脊髓Zic1的功能获得分析（Aruga et al., 2002）， 3。新的转录激活域被定位在Zic2蛋白的N端区和锌指结构域（Mizugishi et al., in press）， 4。通过酵母双杂交鉴定了几种zic结合蛋白。研究了其中一种新发现的Zic蛋白的相互作用在骨骼形态发生中的作用。5.通过微阵列分析确定了小脑发育过程中Zic 1下游靶基因的候选基因（Hoshino et al., 2004）。对其他Zic突变小鼠也进行了微阵列分析。一些候选基因现在被证明在神经元发育的调节中很重要。

In this research project, we investigated following subjects : 1.Clarification of signal transduction pathway controlling the funtion of Zic proteins. 2.Identification of the transcriptioin-activating domain in Zic proteins. 3.Identification of uncharacterized Zic-binding proteins. 4.Understanding the the regulatory mechanism of the identified protein-protein interactions and their significance in the developmental control. 5.Exploration and analysis of the downstream target genes of Zic proteins. As an achievement of the investigation, we revealed following facts : 1.Zic proteins can phycally and functionally interact with Gli proteins, which are the transcriptional mediator of the Hedgehog signal (Koyabu et al., 2001 ; Mizugishi et al., 2001), 2.Zic1 can activate the Notch signaling as indicated by the gain-of-function analysis of Zic1 in chick and mouse spinal cord (Aruga et al., 2002), 3.Novel transcription activating domains were mapped in the N terminal region and zinc finger domain of Zic2 proteins (Mizugishi et al., in press), 4.Severeal Zic-binding proteins was identified by yeast two hybrid assay. The role of interaction in skeletal morphogenesis was investigated as for one of the newly identified Zic proteins. 5.Candidates of the Zic 1 downstream target genes in the course of cerebellar development were identified by microarray analysis (Hoshino et al., 2004). The microarray analysis was also carried out using other Zic mutant mice. Some of the candidate genes were now cleared to be important in the regulation of neuronal development.