Microbial provision of essential amino acids: protein conservation in hibernation

微生物提供必需氨基酸：冬眠中蛋白质的保存

• 批准号: 9978876
• 负责人: Khrystyne Duddleston
• 金额: $ 18.94万
• 依托单位: UNIVERSITY OF ALASKA FAIRBANKS
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9978876
• 关键词: Address; Amino Acids; Anabolism; Attention; Bacteria; Collection; Communities; Data; Deposition; Development; Diet; Dietary Proteins; Diffuse; Disease; Elderly; Essential Amino Acids; Family suidae; Fasting; Fatty acid glycerol esters; Future; Gastrointestinal tract structure; Gene Expression Profile; Genes; Genetic; Goals; Growth; Health; Hibernation; Human; Impairment; In Vitro; Injury; Isotope Labeling; Knowledge; Label; Life Style; Liver; Measures; Metabolic; Metabolism; Metagenomics; Microbe; Muscle; Muscular Atrophy; Nitrogen; Obesity; Pathway interactions; Peritoneal; Phenotype; Physiological; Physiology; Plasma; Play; Process; Production; Protein Biosynthesis; Proteins; Rattus; Reproducibility; Research; Risk; Role; Salvelinus; Sampling; Seasons; Squirrel; Structure; Techniques; Testing; Thinness; Tissues; Urea; Urea Nitrogen; Wasting Syndrome; Work; age-related muscle loss; aminoacid biosynthesis; arctic ground squirrel; density; design; effective intervention; experimental study; fight against; gene synthesis; gut microbes; gut microbiome; gut microbiota; in vivo; member; metabolomics; metatranscriptomics; microbial; microbial community; microbiota; muscle form; next generation sequencing; nitrogen metabolism; preservation; prevent; sarcopenia; sarcopenic obesity; therapeutic target

Project Summary Project 2 – Microbially-liberated urea nitrogen and host essential amino acids. The elderly are particularly susceptible to sarcopenic obesity (SAO), whereby a loss of lean mass (e.g., muscle) accompanies an increase in fat, and which is difficult to treat via life style changes (e.g., diet) designed to target obesity. Although numerous studies have addressed the role of diet and gut microbes as factors in diseases such as obesity, the potential beneficial role of gut microbes in preventing loss of lean mass in disorders such as SAO has received comparably less attention. Urea-nitrogen salvage (UNS) is the process whereby urea is degraded by gut microbes releasing nitrogen that can be utilized by gut microbes to produce amino acids, or be reabsorbed and used by the host. UNS likely plays an important role in nitrogen metabolism in humans, and evidence suggests both UNS and the production of essential amino acids (EAAs) by gut microbes may have important impacts on human health. Yet, despite the availability of microbially-liberated urea-nitrogen (MLUN) for EAA synthesis in the gut, these two microbial components of host nitrogen metabolism have been studied primarily independently and with little focus on the structure and function of the gut microbial community. The goal of this project is to determine the gut microbiota potential for use of MLUN in synthesis of EAAs, and demonstrate the provision of microbially-synthesized EAAs for host protein synthesis. We use the arctic ground squirrel (AGS) as a study species, as AGS are able to preserve lean mass during their long hibernation season. Our hypothesis is that MLUN in the gut of AGS is utilized by gut microbes for synthesis of EAAs which are incorporated into host tissues during hibernation. Our approach relies upon simultaneous analyses of the structure and function of the gut microbial community, microbial production of EAAs using MLUN, and incorporation of microbial-derived EAAs in host tissues under varying conditions of host dietary protein availability and physiological state. In Specific Aims 1 and 2 we utilize isotopically labeled urea (13C and 15N), which when injected intra-peritoneally diffuses into the gut and becomes available for urea degrading microbes. After injecting hibernating squirrels with labeled urea, we will measure 13CO2 in breath (to confirm ureolytic activity), determine the EAA synthesis potential of the gut microbiota using next generation sequencing techniques (metagenomics and metatranscriptomics to look for EAA biosynthesis genes) and metabolomics (15N-NMR to search for labeled EAAs in gut contents), and determine if AGS incorporate microbially-derived EAAs into host tissues (15N-NMR). In Specific Aim 3, we will isolate and characterize bacteria from the GI tract of AGS and determine culture conditions necessary for growth to experiment with mock gut communities in the future. Our approach promises to yield an increased knowledge of the role of the gut microbial community in host nitrogen metabolism and protein conservation, contributing to our understanding of the relationship between the gut microbial community and human health.

项目摘要项目2-微生物释放的尿素氮和宿主必需氨基酸。 老年人特别容易患骨质疏松性肥胖(SAO)，由此瘦体重的损失(例如， 肌肉)伴随着脂肪的增加，而且很难通过设计的生活方式改变(例如，饮食)来治疗 以肥胖为目标。尽管许多研究都提到了饮食和肠道微生物作为影响健康的因素 肠道微生物在预防肥胖等疾病中的潜在有益作用 像SAO这样的疾病得到的关注相对较少。尿素氮回收(UNS)是一个过程 通过肠道微生物释放氮来降解尿素，肠道微生物可以利用这些氮来生产 氨基酸，或被宿主重新吸收和利用。Uns可能在氮代谢中起着重要作用。 在人类中，有证据表明UNS和肠道产生必需氨基酸(EaaS) 微生物可能对人类健康有重要影响。然而，尽管有微生物释放的 尿素氮(MLUN)用于在肠道内合成EAA，这是宿主氮的这两个微生物成分 新陈代谢主要是独立研究的，很少关注细胞的结构和功能。 肠道微生物群落。该项目的目标是确定MLUN使用的肠道微生物区系潜力 在EaAs的合成中，并展示了微生物合成的EaAs为宿主蛋白提供 综合。我们使用北极地松鼠(AGS)作为研究物种，因为AGS能够保持精瘦的质量 在它们漫长的冬眠季节。我们的假设是AGS肠道中的MLUN被肠道微生物利用 用于合成在冬眠期间并入宿主组织的EaAs。我们的方法依赖于 肠道微生物群落结构和功能的同步分析、微生物生产 使用MLUN的EAAS，以及在不同条件下在宿主组织中掺入微生物来源的EAAS 宿主饲料蛋白质的可利用性和生理状态。在特定的目标1和2中，我们使用同位素标记 尿素(13C和15N)，在腹膜内注射时扩散到肠道，并可用于 尿素降解菌。在给冬眠松鼠注射标记尿素后，我们将测量13CO2在 呼吸(确认解脲活性)，使用NEXT确定肠道微生物区系的EAA合成潜力 世代测序技术(寻找EAA生物合成的元基因组学和元转录组学 基因)和代谢组学(15N-核磁共振在肠道内容物中搜索标记的EaAs)，并确定AGS 将微生物衍生的EaAs掺入宿主组织(15N-核磁共振)。在具体目标3中，我们将隔离和 鉴定来自AGS胃肠道的细菌并确定其生长所需的培养条件 在未来尝试模拟肠道社区。我们的方法有望增加知识 肠道微生物群落在宿主氮代谢和蛋白质保存中的作用，有助于 我们对肠道微生物群落与人类健康之间关系的理解。