CATENINS, EPITHELIAL BEHAVIOR AND GENE EXPRESSION

描述（根据研究者摘要逐字附上）：除 它们作为钙粘蛋白和细胞骨架、B-连环蛋白和 斑珠蛋白（γ-连环蛋白）通过与TCF型结合调节基因表达 HMG盒转录因子。连环蛋白-TCF的相互作用是由 经典Wnt信号通路。Wnt信号在多个点上是必不可少的 连环蛋白调节的缺陷与一些 尤其是癌症。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TCF竞争结合连环蛋白。这些SOX可以调节细胞 对Wnt-连环蛋白-TCF信号传导的反应，因此在 Wnt/TCF依赖性事件和致病过程。在爪蟾背腹侧 轴的确定是基于连环蛋白-TCF相互作用，并提供了一个理想的 测试连环蛋白结合SOX在调节 catenin-TCF调控基因表达。我们建议回答三个具体问题 问题. I.连环蛋白结合SOX是否与XLEF 1有效竞争， XTCF 3在体内和体外与B-连环蛋白的结合？我们将使用一个组合 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SOX 与B-连环蛋白/TCF有效竞争结合到特定的调节位点 在目标基因？四个TCF调节的靶启动子，与 爪蟾背腹轴的确定和中胚层的分化， 已鉴定的有Siamois、Twin、Xnr 3和XBra。我们将测试SOX是否 在早期胚胎中表达，并且已知干扰TCF信号传导， 直接连接到这些启动子内的位点，以及SOX是否有效地完成 与TCF结合到特定的调节元件。伊利诺伊州做母亲和 合子SOX在体内调节B-连环蛋白/TCF调节基因的表达？ 连环蛋白结合XSOX 3和XSOX 17 B的异位表达抑制 B-连环蛋白依赖的背轴形成。我们将测试是否减少 使用反义试剂表达特定SOX导致预测的 TCF调节的靶基因的扩增和/或TCF调节的靶基因的敏感性增加。 胚胎细胞对Wnt信号传导成分的作用

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