GPR35 on Vagal Afferent Neurons as a Peripheral Drug Target for Treating Diet-Induced Obesity

项目总结 肥胖是慢性疾病的主要风险因素，如心血管疾病和代谢性疾病，其 全球流行与高卡路里饮食的过度消费是平行的。胃旁路手术是目前世界上 只有有效的治疗才能保持体重减轻。然而，手术是昂贵的，有侵入性的，而且是专为 严重肥胖的人。胃旁路手术的有效性部分归因于 肠道微生物区系和微生物代谢物的组成，以及外周血液产量的增加 饱腹感荷尔蒙。迷走神经传入神经元位于肠壁，表达外周受体 荷尔蒙和微生物代谢物，并将饱腹感信号从胃肠道传递到大脑 限制食物摄取。G蛋白偶联受体35(GPR35)被微生物代谢产物激活，是 在面包车上高度表达。最近的证据表明，面包车上的GPR35与Cackar共同本地化， 介导肠内分泌激素CCK(CCK)诱导饱腹感作用的受体。 面包车对包括CCK在内的肠道饱腹感信号的脱敏先于高脂饮食诱导的体重增加 并在人类肥胖的小鼠模型中出现吞噬过度，并导致食物摄入量增加。高脂肪饮食一直是 显示了降低血浆犬尿酸的水平，犬尿酸是一种微生物代谢物，是一种内源性GPR35配体。 然而，GPR35在外周饱足信号中的作用尚不清楚。初步数据显示， 使用GPR35激动剂扎匹司特减少小鼠的摄食量和体外实验 证明抑制GPR35可降低VANS对CCK的敏感性。因此，我们假设 高脂饮食减少微生物来源的GPR35配体的产生，导致VAN减少 对CCK敏感，抑制肠道饱腹感信号，从而增加能量摄入。假说 将在两个目标上接受考验。目标1将确定CKAR和GPR35在激活VANS和GPR35中的相互作用 大脑中的二级神经元，以及抑制食物摄入的作用。目标2将决定是否增加 GPR35配体的可用性，无论是通过给药益生菌或益生菌，都可以恢复HF诱导的饮食 损坏面包车和控制食物摄入。这一假说将使用体外试验、 活体和活体技术，包括钙成像，RNA干扰敲除面包车中的GPR35， 和自动喂食行为监控。这些研究的成功完成将展示其作用 GPR35在外周饱腹感信号中的作用，并揭示了治疗肥胖的潜在治疗靶点。这个 培训计划将由我的赞助商的指导和加州大学戴维斯分校的特殊设施来推动。这 建议书描述了支持科学和专业的综合和全面的培训计划 发展，并推动我的长期目标，成为一名综合生理学家。

PROJECT SUMMARY Obesity is a major risk factor for chronic diseases, such as cardiovascular and metabolic diseases, and its global prevalence parallels the overconsumption of calorie-dense diets. Gastric bypass surgery is currently the only effective treatment for maintaining weight loss. However, surgery is expensive, invasive, and reserved for people with severe obesity. The effectiveness of gastric bypass surgery is partly attributed to a shift in the composition of the gut microbiota and microbial metabolites, and to the increased production of peripheral satiety hormones. Vagal afferent neurons (VANs) are located in the gut wall, express receptors for peripheral hormones and microbial metabolites, and transmit satiety signals from the gastrointestinal tract to the brain to inhibit food intake. The G-protein coupled receptor 35 (GPR35) is activated by microbial metabolites and is highly expressed on VANs. Recent evidence demonstrates GPR35 on VANs is co-localized with CCKAR, the receptor for mediating the satiety-inducing effects of the enteroendocrine hormone, cholecystokinin (CCK). Desensitization of VANs to intestinal satiety signals, including CCK, precedes high-fat diet-induced weight gain and hyperphagia in mouse models of human obesity and leads to increased food intake. High-fat diet has been shown to reduce plasma levels of kynurenic acid, a microbial metabolite that is an endogenous GPR35 ligand. However, the role of GPR35 in peripheral satiety signaling is unknown. Preliminary data show that activation of GPR35 using the GPR35 agonist, zaprinast, decreases food intake in mice and in vitro experiments demonstrate that GPR35 inhibition decreases the sensitivity of VANs to CCK. Therefore, we hypothesize that high-fat diet decreases the production of microbially-derived GPR35 ligands, leading to reduced VAN sensitivity to CCK, suppression of intestinal satiety signaling thereby increasing energy intake. The hypothesis will be tested in two aims. Aim 1 will determine the interaction of CCKAR and GPR35 in activation of VANs and second order neurons in the brain, and in inhibiting food intake. Aim 2 will determine whether increasing availability of GPR35 ligands, either by administration of prebiotics or probiotics, can restore HF-diet induced impairment of VANs and control food intake. The hypothesis will be tested using a combination of in vitro, intravital, and in vivo techniques including calcium imaging, RNA interference knockdown of GPR35 in VANs, and automated feeding behavior monitoring. Successful completion of these studies will demonstrate the role of GPR35 in peripheral satiety signaling and reveal a potential therapeutic target for treating obesity. The training plan will be facilitated by the mentorship of my sponsor and the exceptional facilities at UC Davis. This proposal describes an integrative and comprehensive training plan to support scientific and professional development and propel me toward my long-term goal of becoming an integrative physiologist.