Studies on the molecular mechanisms leading to development of intestinal metaplasia

我们建立并报道了一种通过壁细胞异常表达CDX 2来研究肠上皮化生分子机制的小鼠模型。利用该模型，在肠上皮化生形成中及其周围的详细研究显示，编码各种肠细胞标志物蛋白的信使RNA表达在肠上皮化生的组织学表型之前被动员。这些发现表明胃粘膜向肠上皮化生的转化是在具有“胃表型”的细胞中启动的，支持我们先前的观察，即在炎性胃粘膜中检测到CDX 2和其他肠标志物信息。在此过渡期，壁细胞标志物H，K-ATP酶的表达与音刺猬（SHH）的表达平行下降，支持SHH可能在维持胃单位中起重要作用。与这一假设雅阁的是，密歇根大学的一组研究人员报告说， ...更多信息 在壁细胞中人工表达的hedgehog相互作用蛋白（HIP）导致酸分泌减少以及壁细胞数量减少。然而，在该模型中没有描述肠上皮化生的发展，表明SHH表达减少不足以形成肠上皮化生。因此，进行相同实验的最初计划被撤回。然而，我们观察到刺猬信号和Wnt信号之间复杂的相互作用，也涉及CDX 2介导的细胞命运改变期间来自间质组织如BMP-4的信号。我们的实验室正在进行这方面的进一步实验。由于CDX 2在诱导肠上皮化生中起关键作用，我们计划检查是否可以通过抑制CDX 2表达来逆转完全发展的肠上皮化生。第一种方法是通过siRNA介导的敲除。我们设计了五种不同的siRNA，并将它们转染到表达CDX 2的细胞系中。然而，不幸的是，没有一种siRNA显示出降低CDX 2表达的任何效果。目前，我们正在构建慢病毒载体系统，以确保更丰富和更长的siRNA表达，这可能是更有效地敲低CDX 2的表达。另一种方法是研究从小鼠模型中获得的组织中的miRNA表达模式，以鉴定调节肠上皮化生发展的关键miRNA。鉴定了miRNA表达中的许多独特变化。通过定量RT-PCR和原位杂交证实这些miRNA表达的改变正在进行中，并将很快报道。少

We have established and reported a mouse model for studying the molecular mechanisms of intestinal metaplasia by expressing CDX2 aberrantly in parietal cells. With this model, detailed studies in and around the formation of intestinal metaplasia revealed that messenger RNA expressions encoding various intestinal cell marker proteins are mobilized preceding the histological phenotype of intestinal metaplasia. These findings indicated that the conversion of gastric mucosa to intestinal metaplasia was initiated in the cells with "gastric phenotype", supporting our previous observation that CDX2 and other intestinal marker messages were detected in the inflammatory gastric mucosa. During this transitional phase, expression of H, K-ATPase, a marker of parietal cell, decreased in parallel with that of sonic hedgehog (SHH), supporting that SHH may be important in maintaining the gastric unit. In accord with this hypothesis, a group of the investigators in the University of Michigan reported t … More hat hedgehog interacting protein (HIP) artificially expressed in the parietal cells resulted in lowered acid secretion as well as decreased number of parietal cells. However, development of intestinal metaplasia was not described in this model, indicating that diminished expression of SHH is not sufficient to form intestinal metaplasia. Thus, initial plan doing the same experiments was withdrawn. However, we observed a complex interplay between hedgehog signaling and Wnt signaling involving also signaling from interstitial tissues such as BMP-4 during CDX2-mediated alteration of cell fate. Further experiments in this line are under way in our laboratory. As CDX2 plays pivotal role in inducing intestinal metaplasia, we planned to examine whether reversal of fully developed intestinal metaplasia is possible by suppressing CDX2 expression. The first approach was by siRNA-mediated knockdown. We designed five different siRNA and transfect them to CDX2 expressing cell lines. Unfortunately, however, none of the siRNA showed any effects of decreasing CDX2 expressions. Currently we are constructing rentivirus vector system to ensure more abundant and longer expression of siRNA that may be more effective in knocking down the CDX2 expressions. Another approach is to study miRNA expression patterns in the tissues obtained from the mice model to identify key miRNAs regulating the development of intestinal metaplasia. A number of unique changes in the miRNA expression were identified. Confirmation of these alterations of miRNA expression by quantitative RT-PCR and in situ hybridization are ongoing and will be reported soon. Less