Analysis of Wnt signaling pathway mediated frizzled protein family

卷曲蛋白作为Wnt受体，参与基因表达和平面细胞极性的调控。由于许多卷曲家族成员的羧基迷你都含有PDZ结合基序，我们分离出了几个可能与卷曲相互作用的候选分子。其中一个相互作用的蛋白，fzip-1，包含两个线圈基序和一个PDZ结构域。由于该分子定位于高尔基体，因此被命名为Golgi-associated PDZ和coil -coil motif containing protein （GOPC）。一系列的分子研究表明，GOPC参与毛质从高尔基体向质膜的转运。此外，雄性GOPC敲除小鼠由于顶体形成异常而不育。电镜分析显示，从高尔基体到顶体的囊泡运输严重受损。由此可见，GOPC除具有质膜外，还具有向顶体的囊泡转运的功能。我们还发现第二个相互作用的分子；fzip-2参与G蛋白依赖性-JNK激活，而第三个分子fzip-3则被认为参与细胞分裂。我们目前正在研究这些分子的分子分析及其基因靶向的生物学意义。

Frizzled proteins play a role as a Wnt receptor and involved in the regulation of gene expression as well as planar cell polarity. Since carboxyl temini of many frizzled family members contain PDZ binding motifs, we isolated several candidate molecules that potentially interact with frizzled.One of these interacting proteins, fzip-1 , contains two coiled-coil motif and one PDZ domain. This molecule was named as Golgi-associated PDZ and coiled-coil motif containing protein (GOPC), as it was localized at the Golgi apparatus. A series of molecular studies indicates GOPC has a role in transport of frizzled form the Golgi apparatus to plasma membrane. Furthermore, Male GOPC knockout mouse was infertile due to abnormal acrosome formation. Electronmicrosopic analysis revealed that vesicle transport from the Golgi apparatus to acrosome was severely impaired. Thus it appears GOPC functions the vesicle transport to acrosome in addition to plasma membrane. We also found that the second interacting molecule; fzip-2, is involved in G protein dependent -JNK activation, whereas the third molecule, fzip-3, is suggested to function in cell division. We are currently investigating the molecular analysis of these molecules as well as their biological significance by gene targeting.