Secreted Frizzled-Related Proteins and Wnt Signaling

我的实验室的重点已经扩大到包括对分泌型FrizzledRelated Proteins(SFRP)和细胞对Wnt刺激的反应的研究。我们已经着手对Wnt蛋白进行纯化，不仅是为了提供试剂以便于SFRP功能的分析，而且也是为了促进Wnt活性和关联信号的研究。确定WNT/FrizzledFZ/SFRP相互作用的特异性是我们的主要目标之一。目前，我们已经纯化了4个重组的SFRP，并在分离3个Wnt蛋白方面取得了进展。我们还筛选了一个低背景Wnt/FZ表达的细胞系，并分别向这些细胞中导入了三种FZs，以帮助我们研究Wnt/FZ/SFRP的结合和信号转导。最近，我们发起了一项合作，研究R-Spinins在Wnt/β-catenin信号转导和肿瘤发生中的作用。我们开发了模型系统来研究依赖Wnt的细胞形状和运动性的变化，以及参与这些过程的非典范Wnt信号。我们已经确定WNT-3a刺激纤维连接蛋白(FN)纤维的组装，这一现象可能有助于细胞的扩散和移动。我们对SFRP-1的长期研究在一系列背景下继续进行。我们已经建立了SFRP1缺失的小鼠模型，我们正在与多个实验室共享该模型，以更好地了解SFRP-1的生理活性。在不同的实验系统中，我们一直在比较和对比SFRP-1和Dickkopf-1(DKK-1)的效果。虽然两者都抑制β-连环蛋白途径，但我们的结果表明，在被SFRP-1阻断的情况下，DKK-1可能会增强非典范信号。除了SFRP-1作为Wnt信号调节因子的公认作用外，我们还在探索它是否有新的结合伙伴和额外的作用机制。综上所述，我们的SFRP和WNT研究将有助于更好地了解它们在癌症、发育和组织动态平衡中的作用。

The focus of my lab has broadened to include both the study of secreted Frizzled-related proteins (sFRPs) and cellular responses to Wnt stimulation. We have embarked on the purification of Wnt proteins, not only to provide reagents to facilitate the analysis of sFRP function, but to foster investigation of Wnt activity and association signaling. Defining the specificity of Wnt/Frizzled (Fz)/sFRP interactions is one of our primary goals. Currently, we have purified four recombinant sFRP and have made progress in the isolation of three Wnt proteins. We also identified a cell line with a low background of Wnt/Fz expression, and separately introduced three Fzs into these cells to assist our study of Wnt/Fz/sFRP binding and signaling. Recently, we initiated a collaboration to investigate the role of R-spondins in the stimuation of Wnt/beta-catenin signaling and tumorigenesis. We developed model systems to examine Wnt-dependent changes in cell shape and motility, and non-canonical Wnt signaling involved in these processes. We have determined that Wnt-3a stimulates the assembly of fibronectinn (FN) fibrils, a phenomenon that likely contributes to cell spreading and movement.Our longstanding study of sFRP-1 has continued in a variery of context. An Sfrp1 null mouse model has been developed, and we are sharing it with multiple labs to better understand the physiological activities of sFRP-1. In various experimental systems, we have been comparing and contrasting the effects of sFRP-1 and Dickkopf-1 (Dkk-1). While both inhibit the beta-catenin pathway, our results suggest that Dkk-1 might enhance non-canonical signaling in situations where it is blocked by sFRP-1. Besides the well-established role of sFRP-1 as a regulator of Wnt signaling, we are exploring the possibility that it has novel binding partners and additional mechanisms of action. Taken together, our sFRP and Wnt studies will contribute to a better understanding of their roles in cancer, development and tissue homeostasis.