STRUCTURE AND FUNCTION OF FRIZZLED-LIKE PROTEINS IN SKELETAL DEVELOPMENT

Frzb是一种分泌型蛋白，最初是从纯化的软骨提取物中分离出来的，它与Wnt受体卷曲家族的半胱氨酸富含结构域(CRD)具有同源性。Wnt蛋白是一种分泌的信号分子，具有多种发育功能，包括骨骼发育和肿瘤发生中的功能障碍。已有研究表明，Frzb可以与Wnt结合并使其失活，从而推测其在改变Wnt诱导的发育和致癌事件方面具有潜在的治疗用途。我们已经证明Frzb在骨骼和颅面发育过程中在时间和空间上都有表达。为了了解Frzb在发育中的作用，我们正在进行条件基因敲除，使用Cre-loxP重组系统。我们首先通过同源重组产生了FRZB基因两侧有loxP位点的FLOXL小鼠。这些小鼠随后在普遍存在的启动子的控制下与表达Cre重组酶的转基因小鼠品系杂交，以在发育早期删除Frzb。零表型似乎是致命的，我们目前正在确定致死性发生在什么阶段。因此，为了观察Frzb基因缺失在面部发育过程中的影响，我们建立了一个转基因小鼠系，在面部间充质中特异性地表达Cre重组酶。这些小鼠在MSX-1启动子的控制下表达Cre，目前正在测试Cre重组酶活性的特异性。-发育、WNT受体、信号

Frzb is a secreted protein, initially isolated from purified cartilage extracts, which shares homology to the cysteine rich domain (CRD) of the frizzled family of Wnt receptors. The Wnt proteins are secreted signaling molecules having numerous developmental functions, including skeletal development, as well as dysfunction in oncogenesis. It has been shown that Frzb can bind to and inactivate Wnt activity, leading to speculation for its potential therapeutic use in modifying Wnt induced developmental and oncogenic events. We have demonstrated that Frzb is temporally and spatially expressed during skeletal and craniofacial development. In an attempt to understand the role of Frzb in development we are conducting a conditional gene knockout, using the Cre-LoxP recombination system. We first generated floxed mice, in which the Frzb gene is flanked by LoxP sites, by homologous recombination. These mice were subsequently crossed to a transgenic mouse line expressing Cre recombinase under the control of a ubiquitous promoter to delete Frzb early in development. The null phenotype appears to be lethal and we are currently determining at what stage the lethality occurs. Consequently, in order to observe the effect that loss of Frzb has during face development we are generating a transgenic mouse line to express Cre recombinase specifically in facial mesenchyme. These mice, which express Cre under the control of the Msx-1 promoter, are currently being tested for the specificity of the Cre recombinase activity. - development, wnt receptors, signaling