CATENINS, EPITHELIAL BEHAVIOR AND GENE EXPRESSION

描述(逐字摘自调查人员摘要)：除 它们作为钙粘附素和细胞骨架之间的连接物，B-连环蛋白和 人血清白蛋白通过与TCF型结合来调节基因表达 HMG-box转录因子。连环蛋白-TCF相互作用受 规范的Wnt信号通路。WNT信令在多个点上是必不可少的 在发育过程中和连环蛋白调节的缺陷与许多 人类疾病，特别是癌症。最近，我们发现了一个意想不到的 连环蛋白-TCF活性调节因子，SOX型HMG盒转录因子 与TCFs竞争与连环蛋白的结合。这些袜子可以调节细胞 对Wnt-catenin-TCF信号的响应，因此在以下方面发挥关键作用 依赖WNT/TCF的事件和致病过程。在非洲爪哇的背腹 轴的确定是基于连环蛋白-TCF的相互作用，并提供了理想的 测试连环蛋白结合SOX在调节中的作用的系统 连环蛋白-TCFs调控基因表达。我们建议回答三个具体问题 问题。连环蛋白结合的SOX能有效地与XLEF1和 XTCF3在体内和体外与B-连环蛋白结合的作用？我们将使用组合 免疫沉淀分析和BlAcore等离子体共振测量 定义这些蛋白质之间的相对和绝对亲和力。二、做SOXS 与B-连环蛋白/TCF有效竞争结合特定调控位点 在目标基因中？四个TCF调控的靶向启动子，与 非洲爪哇背腹轴的测定及中胚层分化 已鉴定为SIAMOIS、Twin、Xnr3和XBra。我们将测试Soxs是否 在早期胚胎中表达，并已知干扰TCF信号，结合 直接到这些推动者内的站点，以及SOX是否有效完成 具有用于绑定特定监管元素的TCFs。生病了。做母性的和 合子Sox在体内调节B-catenin/TCF调节基因的表达？ 连环蛋白结合的XSOX3和XSOX17B的异位表达抑制 B-连环蛋白依赖的背轴形成。我们将测试是否降低 使用反义试剂表达特定的SOX导致预测 TCF调节的靶基因的扩增和/或增加的敏感性 胚胎细胞到Wnt信号组件

DESCRIPTION (appended verbatim from investigator's abstract): In addition to their role as linkers between cadherins and the cytoskeleton, B-catenin and plakoglobin (gamma-catenin) regulate gene expression by binding to TCF-type HMG-box transcription factors. Catenin-TCF interactions are modulated by the canonical Wnt signaling pathway. Wnt signaling is essential at multiple points in development and defects in catenin regulation are associated with a number of human diseases, in particular cancer. Recently, we discovered an unexpected regulator of catenin-TCF activity, SOX-type HMG box transcription factors that compete with TCFs for binding to catenins. These SOXs can modulate cellular responses to Wnt-catenin-TCF signaling, and so play a critical role in Wnt/TCF-dependent events and pathogenic processes. In Xenopus dorsal-ventral axis determination is based on catenin-TCF interactions and provides an ideal system in which to test the role of catenin-binding SOXs in modulating catenin-TCFregulated gene expression. We propose to answer three specific questions. I. Do the catenin-binding SOXs compete effectively with XLEF1 and XTCF3 for binding to B-catenin in vivo and in vitro? We will use a combination of immunoprecipitation analysis and BlAcore plasmon resonance measurements to define relative and absolute affinities between these proteins. II. Do SOXs compete effectively with B-catenin/TCF for binding to specific regulatory sites in target genes? Four TCF-regulated target promoters, associated with dorsal-ventral axis determination and mesoderm differentiation in Xenopus have been identified, i.e. Siamois, Twin, Xnr3 and XBra. We will test whether SOXs expressed in the early embryo, and known to interfere with TCF signaling, bind directly to sites within these promoters and whether SOXs complete effectively with TCFs for binding to specific regulatory elements. Ill. Do maternal and zygotic SOXs modulate the expression of B-catenin/TCF regulated genes in vivo? Ectopic expression of catenin-binding XSOX3 and XSOX17B inhibits B-catenin-dependent dorsal axis formation. We will test whether decreasing the expression of specific SOXs using anti-sense reagents leads to the predicted expansion of TCF regulated target genes and/or increased sensitivity of embryonic cells to Wnt signaling components