Gut microbiota and obesity: studies in gnotobiotic mice

肠道微生物群和肥胖：对无菌小鼠的研究

基本信息

批准号：
7422345
负责人：
JEFFREY I GORDON
金额：
$ 33.41万
依托单位：
WASHINGTON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-08-01 至 2010-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7422345
关键词：
Adipocytes Adipose tissue Adult Affect Age Alleles Animals Antibiotics Bacteria Bacterial Typing Bacteroides Bacteroides thetaiotaomicron Binding Proteins Biological Assay Biological Markers Biology Birth Body Weight Body Weight decreased Body fat Carbohydrates Cell Nucleus Cells Cessation of life Cognitive Collection Consumption DEXA Deposition Development Diet Dietary Carbohydrates Dietary Polysaccharide Digestion Distal Dual-Energy X-Ray Absorptiometry Ecology Energy Metabolism Environmental Risk Factor Enzymes Epidemic Epithelial Equilibrium Evolution Fasting Fat-Restricted Diet Fatty Acids Fatty acid glycerol esters Fatty-acid synthase Foundations Gender Gene Targeting Genes Genetic Genetic screening method Genetically Engineered Mouse Genome Genomics Germ Germ-Free Glucose Gnotobiotic Harvest Hepatic Hepatocyte Home environment Human Hyperplasia Hypertrophy Inbred Strain Indigenous Indirect Calorimetry Insulin Insulin Resistance Intestines Knock-out Knockout Mice Lactobacillus Lead Learning Leptin Leucine Zippers Life Liver Locales Measures Mediating Mediator of activation protein Metabolic Metabolism Microbe Molecular Monosaccharides Mus Muscle NMRI Mouse Nuclear Import Numbers Nutrient Obesity Organ Pathway interactions Pentosephosphate Pathway Peripheral Phenocopy Phenotype Physiological Plants Polysaccharides Predisposition Process Production Protein Phosphatase 2A Regulatory Subunit PR53 Protein Serine/Threonine Phosphatase Proteins Rate Regulation Response Elements Role SRE-1 binding protein Serum Skeletal Muscle Standards of Weights and Measures Sterols Structure Symbiosis Techniques Testing Therapeutic Thinking Thinness Time Transgenes Tricarboxylic Acids Triglycerides Week Weight Wild Type Mouse acrosome stabilizing factor adiponectin attenuation base carbohydrate binding protein carbohydrate receptor cell type concept day energy balance feeding functional genomics genome sequencing in vivo intestinal epithelium knockout animal lipid biosynthesis lipoprotein lipase lipoprotein lipase inhibitor member microbial microbial community microbial host microbiome microorganism novel therapeutics research study response sugar transcription factor xylulose-5-phosphate

项目摘要

DESCRIPTION (provided by applicant): Developing non-cognitive approaches for treating obesity is imperative. We have been using gnotobiotic mice to examine the significance of human-bacterial symbioses in the gut, and discovered that the intestinal microbiota has a remarkable effect on fat storage. Colonization ('conventionalization') of adult germ-free (GF) C57B1/6 (B6) mice with a cecal microbiota harvested from conventionally-raised mice produces a 60% increases in total body fat content and white adipose tissue (WAT) weight. This rapid increase occurs despite decreased chow consumption and increased metabolic rate, is sustained, and accompanied by increased leptin levels, insulin resistance, and increased hepatic lipogenesis. The lipogenic response is associated with increased nuclear import of carbohydrate response element binding protein (ChREBP), modest increases in insulin-responsive SREBP-1, and trans-activation of ChREBP/SREBPl lipogenic gene targets. WAT hypertrophy is associated with increased LPL activity and intestine-specific transcriptional suppression of Fiaf (encodes a secreted LPL inhibitor). Moreover, GF Fiaf knockout mice have higher WAT LPL activity and the same body fat content as 'conventionalized' (Fiaf-suppressed) wild-type (wt) littermates: their fat stores are not increased further with conventionalization. These results suggest the following testable hypothesis: (a) microbial processing of otherwise indigestible dietary polysaccharides (PS) provides monosaccharides that lead to ChREBP, and possibly, SREBP-1- stimulation of hepatic lipogenesis: (b) microbial suppression of intestinal Fiaf, combined with the lipogenic response, promotes LPL-mediated increases in adipocyte fat storage; (c) increasing Fiaf expression and/or activity should promote leanness. Aim 1- Use wt B6 mice to determine the role of dietary carbohydrates and microbial ecology on microbiota-induced fat storage. GF and conventionalized mice will be fed isocaloric high PS/low fat, .high fat/low PS, or high sugar/low fat diets, and the effects on body fat content, VO2, feptin/glucose/insulin, WAT LPL, and intestine/liver/muscle energy metabolism assayed. Microbial requirements will be assessed by colonization with all or some components of a simplified 8-member microbiota (Altered Schaedler Flora). Aim 2- Determine the contribution of the microbiota-associated hepatic lipogenic response by conventionalizing GF mice with a ChREBP knockout, a SREBP-1 c knockout, combined ChREBP and SREBP-1 c deficiencies, or a hepatocyte-specific Fasl knockout. Aim 3- Introduce a transgene constitutively expressed in the small intestinal epithelium into Fiaf-/- mice. We predict that these mice will phenocopy leaner GF wt mice, whether or not they have been colonized [proof-of-concept genetic test of whether therapeutic manipulations that increase Fiaf expression (or activity) will promote leanness].

描述（由申请人提供）：开发治疗肥胖的非认知方法势在必行。我们一直在使用无菌小鼠来研究人类与细菌在肠道中共生的重要性，并发现肠道微生物群对脂肪储存有显着的影响。将传统饲养小鼠的盲肠微生物群移植到成年无菌 (GF) C57B1/6 (B6) 小鼠中（“常规化”），可使总体脂肪含量和白色脂肪组织 (WAT) 重量增加 60%。尽管食物消耗减少和代谢率增加，但这种快速增加仍然持续，并伴随着瘦素水平增加、胰岛素抵抗和肝脏脂肪生成增加。脂肪生成反应与碳水化合物反应元件结合蛋白(ChREBP)的核输入增加、胰岛素反应性SREBP-1的适度增加以及ChREBP/SREBP1脂肪生成基因靶标的反式激活相关。 WAT 肥大与 LPL 活性增加和 Fiaf（编码分泌型 LPL 抑制剂）肠道特异性转录抑制有关。此外，GF Fiaf 基因敲除小鼠与“常规化”（Fiaf 抑制的）野生型（wt）同窝小鼠具有更高的 WAT LPL 活性和相同的身体脂肪含量：它们的脂肪储存不会因常规化而进一步增加。这些结果表明以下可检验的假设：(a) 微生物加工其他难以消化的膳食多糖 (PS) 提供单糖，从而导致 ChREBP，并可能导致 SREBP-1- 刺激肝脏脂肪生成：(b) 微生物抑制肠道 Fiaf，结合与脂肪生成反应一起，促进 LPL 介导的脂肪细胞脂肪储存的增加； (c) 增加 Fiaf 表达和/或活动应促进瘦身。目标 1 - 使用 wt B6 小鼠确定膳食碳水化合物和微生物生态对微生物诱导的脂肪储存的作用。 GF和常规小鼠将被喂食等热量高PS/低脂、高脂/低PS或高糖/低脂饮食，以及对身体脂肪含量、VO2、feptin/葡萄糖/胰岛素、WAT LPL和肠道的影响检测/肝脏/肌肉能量代谢。微生物需求将通过简化的 8 成员微生物群（Altered Schaedler Flora）的全部或部分成分的定植来评估。目标 2- 通过将 ChREBP 敲除、SREBP-1 c 敲除、ChREBP 和 SREBP-1 c 联合缺陷或肝细胞特异性 Fasl 敲除的 GF 小鼠常规化，确定微生物群相关的肝脏脂肪生成反应的贡献。目标 3- 将在小肠上皮细胞中组成型表达的转基因引入 Fiaf-/- 小鼠。我们预测这些小鼠将表现出更瘦的 GF wt 小鼠，无论它们是否已被定植 [增加 Fiaf 表达（或活性）的治疗操作是否会促进瘦身的概念验证基因测试]。