A Zebrafish Model to Study the Role of the Microbiota in the Etiology of Intestin

描述(申请人提供)：人体胃肠道内有大量复杂的微生物群落，这些微生物对正常健康很重要，但也可能导致胃肠道癌症等疾病。在这项提案中，我们将使用斑马鱼模型来研究肠道微生物产生的因素如何与宿主遗传因素相互作用来驱动肠癌的进展。我们将利用斑马鱼品系，这些品系由于Wnt信号通路过度激活、慢性炎症或DNA修复机制丧失而容易患上肠癌，所有这些都与人类的胃肠癌有关。在我们的第一个目标中，我们将表征一些由人类和斑马鱼相关细菌产生的分泌蛋白，这些蛋白调节与胃肠道癌症发展相关的宿主程序，包括上皮细胞增殖和炎症。我们将确定促增殖蛋白是否与易患癌症的遗传背景协同作用，扰乱正常的肠上皮更新程序并导致增殖，此外，抗炎蛋白是否对增殖具有保护作用。在我们的第二个目标中，我们将鉴定一个表达胃癌相关病原体幽门螺杆菌的细菌癌基因CagA的转基因斑马鱼系。我们将确定在这些转基因鱼向增殖和癌症发展过程中激活的宿主遗传程序，并测试这些途径中的哪些是CagA致癌特性所必需的。我们还将测试CagA的表达是否以促进肠道病理的方式改变肠道微生物群落。在我们的第三个目标中，我们将调查 我们的斑马鱼设施爆发了自发性肠癌，我们已经证明这种癌症是可以传播的。我们将使用传染性疾病的实验框架来鉴定与肠道病理相关的微生物。我们将利用我们的易患癌症的斑马鱼品系来表征与疾病相关的微生物群落和单个候选微生物的致癌潜力。这项研究将通过肠道微生物促进癌症发展的机制提供新的见解，并最终导致诊断、治疗和预防人类胃肠道癌症的新方法。

DESCRIPTION (provided by applicant): The human gastrointestinal tract houses large and complex communities of microorganisms that are important for normal health, but can also contribute to diseases such as gastrointestinal cancer. In this proposal we will use a zebrafish model to investigate how factors produced by gut microbes interact with host genetic factors to drive the progression of intestinal cancer. We will make use of zebrafish lines that are predisposed to intestinal cancer due to over-activation of the Wnt signaling pathway, chronic inflammation, or loss of DNA repair mechanisms, all of which are commonly associated with gastrointestinal cancers in humans. In our first aim we will characterize a number of secreted proteins, produced by both human and zebrafish-associated bacteria, that modulate host programs associated with gastrointestinal cancer development, including epithelial cell proliferation and inflammation. We will determine whether the pro-proliferative proteins interacts synergistically with cancer-prone genetic backgrounds to disrupt normal programs of intestinal epithelial renewal and cause hyperplasia, and furthermore whether the anti-inflammatory proteins confer protection against hyperplasia. In our second aim we will characterize a transgenic zebrafish line that expresses the bacterial oncogene, CagA, from the stomach cancer-associated pathogen Helicobacter pylori. We will determine the host genetic programs that are activated during the progression of these transgenic fish to hyperplasia and cancer, and we will test which of these pathways are required for CagA's carcinogenic properties. We will also test whether CagA expression alters the intestinal microbial community in ways that promote intestinal pathology. In our third aim we will investigate the microbial etiology behind an outbreak of spontaneous intestinal cancers in our zebrafish facility, which we have shown to be transmissible. We will use the experimental framework of transmissible disease to identify microbes associated with intestinal pathology. We will employ our cancer- prone zebrafish lines to characterize the carcinogenic potential of disease-associated microbial communities and of individual candidate microbes. This research will provide new insight into the mechanisms by with intestinal microbes contribute to cancer development and will ultimately lead to new approaches to diagnose, treat and prevent gastrointestinal cancers in humans.