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

描述（由申请人提供）：干细胞有望成为治疗疾病、控制组织再生、递送治疗剂和替代患病细胞群体的治疗方法。然而，干细胞的操作只能通过了解它们是如何被调节的来实现。越来越明显的是，这种调节是通过来自其专门环境（生态位）的环境线索来实现的。虽然许多信号传导途径影响干细胞活性，但β-连环蛋白信号传导深刻地影响干细胞命运，在诱导或消融时诱导不同的细胞反应。最近，我们已经表明，在肠道发育过程中，在干细胞龛中过度表达Wnt/β-连环蛋白信号会影响干细胞的增殖能力。基于这些数据，我们认为Wnt/β-catenin信号通路在建立发育中的肠干细胞生态位和维持成人的成熟生态位中起着重要作用。本研究的目的是检验Wnt/β-连环蛋白信号传导以时间方式组织以建立肠干细胞生态位和以空间方式组织以维持成熟生态位内的增殖分化进程的假设。为了验证这一假设，我们将使用Wnt-报告基因和DNTcf-4表达小鼠（消融的Wnt/β-连环蛋白信号传导）来表征干细胞小生境形态发生和成年期间Wnt/β-连环蛋白活性的时间和空间表达模式。此外，我们将通过解剖和分析龛内的离散细胞层来确定Wnt/β-连环蛋白信号传导的空间表达是否是维持成体干细胞龛所必需的。通过诱导β-连环蛋白信号分子或DNTcf-4分子破坏Wnt/β-连环蛋白的正常表达将决定信号传导对隐窝建立和维持的依赖性。最后，DNA微阵列分析将鉴定发育中的干细胞龛（野生型和DNTcf-4肠）的细胞区域之间基因表达的总体变化，以直接确定Wnt/β-连环蛋白信号传导对分子和途径刺激的作用。这些拟议的研究将直接检查Wnt/β-连环蛋白信号传导对维持干细胞生态位的作用，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.