b-catenin's role in establishing the gut stem cell niche

描述(申请人提供)：干细胞有望成为一种治疗疾病的方法，控制组织再生，输送治疗剂，并有可能替代患病的细胞群体。然而，干细胞的操作只有在了解它们是如何被调控的基础上才能实现。越来越明显的是，这一规定是通过其专门环境(利基)发出的环境线索来实现的。虽然许多信号通路影响干细胞的活性，但β-连环蛋白信号深刻地影响干细胞的命运，在诱导或消融时诱导不同的细胞反应。最近，我们已经证明，在肠道发育过程中，干细胞巢中Wnt/β-catenin信号的过度表达会影响干细胞的增殖能力。基于这一数据，我们认为Wnt/β-catenin信号通路在成人建立发育中的肠道干细胞生态位和维持成熟生态位中起着重要作用。本研究的目的是验证Wnt/β-catenin信号在时间上被组织以建立肠道干细胞生态位，并在空间上被组织以维持成熟生态位内从增殖到分化的过程的假设。为了验证这一假设，我们将使用Wnt-Report和DNTcf-4表达的小鼠(去除的Wnt/β-catenin信号)来表征Wnt/β-catenin活性在干细胞生态位形态发生和成年过程中的时空表达模式。此外，我们将通过解剖和分析巢内离散的细胞层来确定是否需要Wnt/β-catenin信号的空间表达来维持成体干细胞巢。通过诱导β-连环蛋白信号分子或DNTcf-4分子干扰Wnt/β-连环蛋白的正常表达，将决定信号对隐窝建立和维持的依赖性。最后，DNA微阵列分析将确定发育中的干细胞利基细胞区域(野生型和DNTcf-4肠道)之间基因表达的全球变化，以直接确定Wnt/β-catenin信号在分子和途径刺激中的作用。这些拟议的研究将直接检查Wnt/β-catenin信号在维持干细胞生态位中的作用，并将深入了解肠道干细胞的调控。

DESCRIPTION (provided by applicant): Stem cells hold the promise of a therapeutic approach for treating disease, the control of tissue regeneration, the delivery of therapeutic agents and potential for replacement of a diseased cell population. However, manipulation of stem cells can only be achieved by understanding how they are regulated. It is increasingly evident that this regulation is achieved by environmental cues emanating from their specialized environment (niche). While many signaling pathways influence stem cell activity, beta-catenin signaling profoundly impacts the stem cell fate, inducing divergent cellular responses when induced or ablated. Recently, we have shown that during intestinal development over-expressing Wnt/beta-catenin signaling in the stem cell niche impacts the stem cell's proliferative capacity. Based on this data we believe that the Wnt/beta-catenin signaling pathway plays an important role in establishing the developing intestinal stem cell niche and maintaining the mature niche in the adult. The goal of this study is to test the hypothesis that Wnt/beta-catenin signaling is organized in a temporal manner to establish the intestinal stem cell niche and in a spatial manner for maintenance of the proliferation-to-differentiation progression within the mature niche. To test this hypothesis we will use Wnt-reporter and DNTcf-4 expressing mice (ablated Wnt/beta-catenin signaling) to characterize the temporal and spatial expression pattern of Wnt/beta-catenin activity during the stem cell niche morphogenesis and adulthood. Additionally we will determine if spatial expression of Wnt/beta-catenin signaling is required to maintain the adult stem cell niche by dissecting and analyzing discrete cell strata within the niche. Disruption of the normal expression of Wnt/beta-catenin by induction of a beta-catenin signaling molecule or a DNTcf-4 molecule will determine the dependence of signaling upon crypt establishment and maintenance. Finally, DNA microarray analysis will identify global changes in gene expression between the cellular regions of the developing stem cell niche (wild-type and DNTcf-4 intestines) to directly determine the role of Wnt/beta-catenin signaling on stimulation of molecules and pathways. These proposed studies will directly examine the role of Wnt/beta-catenin signaling on maintenance of the stem cell niche and will shed insight into the regulatory control of intestinal stem cells.