Role of BMP Signaling in Intestine Stem Cell Development

描述(申请人提供)：肠道结构是由沿着绒毛-隐窝轴的一系列区域组成的，在这些区域中细胞的自我更新、增殖、分化和凋亡正在进行。出生后肠道的再生是由肠道干细胞(ISCs)驱动的，ISCs具有自我更新的能力，并且具有多能性，产生四种不同类型的上皮细胞系。到目前为止，对这一顺序发育过程的调控在很大程度上仍然是未知的。尽管已有报道称干细胞位于距墓穴基座的第4或第5位置，但尚无生物标志物可用于识别和定位干细胞的命运。ISC利基的细胞成分也没有确定。我们已经建立了一个BMPRIA基因敲除突变小鼠系，以探索BMP信号在调节ISC发育中的作用。这个突变的小鼠模型在胃肠道中形成了大量的息肉，类似于人类幼年息肉病，随之而来的是越来越多的ISCs和祖细胞。在这些小鼠中，我们发现了与ISCs自我更新、增殖、分化和凋亡区域相关的区域化BMP活性。这项研究计划是为了验证我们的理论：1)BMP的分区活性决定了ISCs经历顺序发育的区域，2)使用我们最近通过对Bmprla突变小鼠的分析而鉴定的ISC-SM1分离和鉴定肠干细胞，以及3)使用N-钙粘素作为表面标记分离和鉴定ISC候选生态位细胞。我们相信，这些研究的结果将为理解肠道干细胞的特性和肠道再生提供重要的见解。对ISCs及其利基细胞的鉴定和分离不仅为研究干细胞的体外行为开辟了新的途径，而且在干细胞移植和基于干细胞的胃肠道疾病替代治疗领域也具有临床意义。

DESCRIPTION (provided by applicant): The intestinal architecture is composed of a sequential array of zones along the villus-crypt axis in which cellular self-renewal, proliferation, differentiation, and apoptosis is ongoing. Postnatal regeneration of the intestines is driven by intestinal stem cells (ISCs), which have the ability to regenerate by self-renewal and are multipotent, giving rise to four different types of epithelial lineages. Thus far, regulation of this sequential developmental process remains largely unknown. Although ISCs have been reported to be located at the 4th or 5th position from the crypt base, no biological marker is available for recognition and mapping the fate of ISCs. Nor has the cellular component of the ISC niche been identified. We have generated a BMPRIA knockout mutant mouse line to explore the roles of the BMP signal in regulating ISC development. This mutant mouse model develops profuse polyps in the gastrointestinal tract resembling human juvenile polyposis, and with it an increased number of ISCs and progenitor cells. In these mice we have found compartmentalized BMP activity which ties in with the zones of ISCs self-renewal, proliferation, differentiation, and apoptosis. This research proposal is to test our theories that 1) the compartmentalized BMP activity determines the zones in which ISCs undergo sequential development, 2) to isolate and characterize intestinal stem cells using ISC-SM1 which we identified recently through analysis of the Bmprla mutant mice, and 3) to isolate and characterize ISC candidate niche cells using N-cadherin as the surface marker. We believe that the results derived from these studies will provide important insight into understanding the properties of intestinal stem cells and intestinal regeneration. Identification and isolation of both ISCs and their niche cells will not only open a new avenue for studying stem cell behavior in vitro, but will also have clinical implications in the areas of stem cell transplantation and stem cell-based replacement therapy for gastrointestinal diseases.