Gastric control of the Intestinal Microbiome and Obesity

项目摘要 我们已经发现，一种专门在胃窦中产生的蛋白质，称为gastrokine-1（Gkn 1），是一种蛋白质。 饮食诱导的肥胖症的基本调节剂。我们的总体目标是阻断Gkn 1以减少或预防肥胖， 并探讨Gkn 1调控肥胖的机制。Gkn 1的表达是组成性的和丰富的 （总胃RNA的1%），并且所得的18 kDa蛋白质对蛋白酶变性具有高度抗性， 去污剂和离液剂。Gkn 1随粘液沿着分泌到胃腔中，并通过胃粘膜。 整个胃肠道完整。Gkn 1修饰结肠腔中的微生物，这表明 Gkn 1对肥胖的影响可能是通过与肠道微生物的相互作用来调节的。事实上，Gkn 1-/-小鼠， 高脂饮食（HFD），抵抗体重增加和抵抗肠道微生物组的变化， 通常发生在HFD上。Gkn 1 +/-（对照）小鼠表现出增加的厚壁菌门百分比， 变形菌和拟杆菌减少，这不会发生在Gkn 1-/-小鼠。我们还发现 成年Gkn 1-/-小鼠的所有脂肪垫中都有大量的棕色/米色脂肪， 在Gkn 1 +/-小鼠中观察到。因此，胃中产生的Gkn 1与远端肠道中的微生物结合， 饮食引起的微生物组、脂肪代谢和肥胖的改变。由于Gkn 1是一种蛋白质， 我们的第一个假设是，阻断Gkn 1将稳定肠道微生物组，并防止饮食- 诱发性肥胖Gkn 1蛋白阻止淀粉样纤维的组装，淀粉样纤维是在 许多蛋白质。淀粉样蛋白由许多细菌产生以促进生物膜形成和粘附。以来 我们观察到Gkn 1装饰在微生物的外部，我们的第二个假设是Gkn 1与细菌结合， 淀粉样蛋白以防止粘附和/或生物膜形成。为了验证这些假设，我们将讨论 以下目标：1.确定阻断微生物组和饮食诱导的Gkn 1调节的疗法 体内肥胖。2.检查Gkn 1对微生物生物膜形成和粘附的影响。这些 研究将描述食品补充剂（鸡蛋粉）如何有效治疗肥胖，并将 确定Gkn 1调节肠道微生物的机制，这将为未来的工作提供方向 来操纵微生物组以改善健康。此外，胃在人体内起着关键作用的概念 远端肠道微生物组和肥胖的调节是前所未有的， 关于目前肥胖症的外科和药物治疗。

Project Abstract We have found that a protein made exclusively in the antrum of the stomach, called gastrokine-1 (Gkn1), is an essential regulator of diet-induced obesity. Our overall goals are to block Gkn1 to reduce or prevent obesity, and to determine the mechanism of Gkn1 regulation of obesity. Gkn1 expression is constitutive and abundant (1% of total stomach RNA) and the resulting 18kDa protein is highly resistant to denaturation by proteases, detergents and chaotropic agents. Gkn1 is secreted along with mucus into the stomach lumen and travels the entire length of the gastrointestinal tract intact. Gkn1 decorates microbes in the lumen of the colon, suggesting that Gkn1 effects on obesity might be regulated by its interaction with gut microbes. Indeed Gkn1-/- mice, on a high fat diet (HFD), are resistant to weight gain and resistant to changes in the intestinal microbiome that typically occur on a HFD. Gkn1+/- (control) mice exhibit increased percentages of Firmicutes and Proteobacteria, and reduction of Bacteroidetes, on a HFD and this does not occur in Gkn1-/- mice. We also find that adult Gkn1-/- mice have significant quantities of brown/beige fat in all of their fat pads, which is not observed in Gkn1+/- mice. Thus Gkn1, made in the stomach, binds to microbes in the distal gut and modulates diet-induced alterations in the microbiome, fat metabolism, and obesity. Since Gkn1 is a protein found in the lumen of the gut, our first hypothesis is that blocking Gkn1 will stabilize the gut microbiome and prevent diet- induced obesity. Gkn1 protein prevents assembly of amyloid fibers, which are a structural feature found in many proteins. Amyloids are produced by many bacteria to facilitate biofilm formation and adherence. Since we observe Gkn1 decorating the outside of microbes, our second hypothesis is that Gkn1binds to bacterial amyloids to prevent adherence and/or biofilm formation. To test these hypotheses we will address the following aims: 1. Identify therapies that block Gkn1 regulation of the microbiome and diet-induced obesity in vivo. 2. Examine the effect of Gkn1 on microbial biofilm formation and adherence. These studies will delineate how a food supplement (egg meal) can be effective for treatment of obesity and will identify mechanisms whereby Gkn1 regulates intestinal microbes, which will provide direction for future efforts to manipulate the microbiome to improve health. In addition, the concept that the stomach plays a key role on the regulation of the distal gut microbiome and obesity is entirely unprecedented and will have a direct impact on current surgical and mediacl therapies for obesity.