Gastric control of the Intestinal Microbiome and Obesity

项目摘要 我们已经发现，一种专门在胃窦部产生的蛋白质，称为胃动素-1(GKN1)，是一种 饮食诱导肥胖的基本调节剂。我们的总体目标是阻断GKN1以减少或预防肥胖， 并探讨GKN1调节肥胖的机制。GKN1的表达是结构性的和丰富的 (占胃总RNA的1%)，所产生的18 kDa蛋白质高度抵抗蛋白酶的变性， 洗涤剂和杂色剂。GKN1与粘液一起分泌到胃腔内，并通过 整个胃肠道都完好无损。GKN1修饰了结肠腔内的微生物，这表明 GKN1对肥胖的影响可能是通过它与肠道微生物的相互作用来调节的。事实上，GKN1-/-小鼠，在一个 高脂饮食(HFD)，抵抗体重增加和肠道微生物群的变化 通常发生在HFD上。GKN1+/-(对照组)小鼠表现出更高的氟米松百分比和 在HFD上，变形杆菌和类杆菌减少，这在GKN1-/-小鼠中不会发生。我们还发现 成年GKN1-/-小鼠的所有脂肪垫中都有大量的棕色/米色脂肪，而这些脂肪并不是 在GKN1+/-小鼠中观察到。因此，在胃中制造的GKN1与远端肠道中的微生物结合并调节 饮食引起的微生物群、脂肪代谢和肥胖的改变。由于GKN1是一种蛋白质，发现于 我们的第一个假设是，阻断GKN1将稳定肠道微生物群，防止饮食- 诱导性肥胖。GKN1蛋白阻止淀粉样纤维的组装，这是在 很多蛋白质。淀粉样蛋白是由许多细菌产生的，以促进生物膜的形成和粘连。自.以来 我们观察到GKN1装饰着微生物的外表，我们的第二个假设是GKN1与细菌结合 淀粉样蛋白，防止粘连和/或生物膜形成。为了检验这些假设，我们将讨论 以下目标：1.找出阻断GKN1调节微生物群和饮食诱导的治疗方法 活体肥胖症。2.检测GKN_1对微生物生物膜形成和黏附的影响。这些 研究将描述食物补充剂(蛋粉)如何有效治疗肥胖症 确定GKN1调节肠道微生物的机制，这将为未来的努力提供方向 操控微生物群以改善健康。此外，胃部起着关键作用的概念 对远端肠道微生物群和肥胖的调节是完全史无前例的，将产生直接影响 关于目前肥胖症的外科和内科治疗方法。

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.