RBP2 Biology and Pathobiology

RBP2 生物学和病理学

• 批准号: 10409772
• 负责人: WILLIAM S BLANER
• 金额: $ 47.97万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-06-15 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10409772
• 关键词: 2-arachidonylglycerol; Adipose tissue; Adult; Affect; Affinity; Age; All-Trans-Retinol; Binding; Binding Proteins; Biochemical; Biochemical Pathway; Biology; Biophysics; Body Weight; Carotenoids; Cell Culture Techniques; Cells; Chylomicrons; Crystallization; Data; Development; Diet; Dietary Fats; Eating; Energy Metabolism; Enterocytes; Esters; Fasting; Fatty Liver; Fatty acid glycerol esters; Gene Expression; Glucose; Goals; Health; Hepatic; High Fat Diet; In Vitro; Intestines; Ligand Binding; Lipids; Literature; Maintenance; Mediating; Metabolic; Metabolism; Molecular; Monoglycerides; Mucous Membrane; Mus; Obesity; Oral; Phenotype; Physiological; Process; Property; Proteins; Publishing; Regulation; Research; Retinaldehyde; Retinoids; Retinol Binding Proteins; Role; Serum; Signaling Molecule; Site; Small Intestines; Structure; Study models; Tissues; Tretinoin; Triglycerides; Unsaturated Fats; Vitamin A; Wild Type Mouse; absorption; analog; base; dietary; feeding; impaired glucose tolerance; jejunum; male; metabolic phenotype; mouse model; novel; prevent; reproductive; response; uptake

Retinol-binding protein 2 (RBP2) was originally identified more than 30 years ago as an intracellular binding protein for retinoids (vitamin A and its metabolites). RBP2 is expressed solely in the adult small intestine, primarily in the jejunum, and has been studied only from the context of its actions in dietary retinoid uptake and metabolism. We unexpectedly have identified a role for RBP2 in the maintenance of body weight, normal responses to a glucose challenge, and normal fasting hepatic triglyceride levels. When maintained solely on a control chow diet, 6–7 month-old male Rbp2-deficient (Rbp2-/-) mice accrue significantly more body weight as white adipose tissue, respond significantly less well to a glucose challenge, and possess significantly more hepatic fat than matched wild type littermate controls. These same metabolic phenotypes are observed when 2 month-old male Rbp2-/- mice are fed a high fat diet for 6 weeks or longer. Although we attempted to identify retinoid-dependent mechanisms that might account for these metabolic phenotypes, we did not detect any differences in tissue retinoic acid levels or in retinoid-regulated gene expression that could explain the metabolic phenotypes of the Rbp2-/- mice. Through biochemical studies, we established that RBP2 binds monoacylglycerols (MAGs), including both 1- and 2-arachidonoylglycerol, 2-oleoylglycerol, and 2-linoyleoylglycerol with very high affinities, comparable to that of retinol binding to RBP2. Based on these and other data, we concluded that RBP2 is a physiologically relevant MAG-binding protein. We are proposing to obtain in depth understanding of role(s) that RBP2 has in mediating enterocyte MAG metabolism. We view this as a first step towards our long-term goal of identifying the molecular processes that underlie the metabolic phenotypes we have observed in both chow fed and high fat diet fed male Rbp2-/- mice. We hypothesize that these phenotypes involve the actions of RBP2 as a MAG-binding protein. To this end, we propose 3 Specific Aims. In Specific Aim 1, we will identify non-retinoid lipids that are able to bind RBP2 and establish the structural properties of RBP2 that facilitate or prevent non-retinoid ligand binding to RBP2. In Specific Aim 2, we will elucidate RBP2-mediated biochemical pathways related to MAG uptake and metabolism within intestinal enterocytes. In Specific Aim 3, we will investigate in mice how RBP2 acts within the jejunum to affect metabolic phenotype development in response to feeding of different high fat diets consisting of either predominantly saturated or predominantly unsaturated fat and how these diets affect MAG and retinoid/carotenoid absorption and metabolism.

视黄醇结合蛋白2（RBP2）最初在30年前被鉴定为类维生素A（维生素A及其代谢产物）的细胞内结合蛋白。 RBP2仅在成年小肠中表达，主要是在空肠的小肠中，并且仅从其在饮食类视网膜类似摄取和代谢中的作用的背景下进行研究。我们出乎意料地确定了RBP2在维持体重，对葡萄糖挑战的正常反应以及正常禁食的肝甘油三酸酯水平中的作用。当仅维持对照食物饮食时，6-7个月大的雄性RBP2 - / - 小鼠的体重明显高于白色脂肪组织，对葡萄糖挑战的反应明显较小，并且可能比匹配的野生型乱货物对照组更少。当我们试图识别可能解释这些代谢表型的类视黄素依赖机制时，观察到这些相同的代谢表型，尽管我们试图识别类维生素类似依赖的机制，但我们没有检测到类类维生素酸水平的任何差异，或者在类似性的基因表达中可能解释了可能解释的基因表达，这可能解释了可能解释了代谢典型的代谢均型 - rbpp2-rbpp2-ice-mice-ice-mIce。通过生化研究，我们确定RBP2结合单酰甘油（MAG），包括1和2-芳基二烯丙基甘油，2-烯酰甘油和2-烯酰甘油烯丙基甘油和2-氯酰甘油，具有非常高的亲亲和性，与视网膜醇与RBP2的结合相比。基于这些和其他数据，我们得出结论，RBP2是一种与物理相关的磁结合蛋白。我们提议深入了解RBP2在介导肠球菌MAG代谢中具有的作用。我们认为这是朝着确定分子过程的长期目标迈出的第一步，即我们在Chow喂养和高脂饮食中观察到的代谢表型的基础。我们假设这些表型涉及RBP2作为磁结合蛋白的作用。为此，我们提出了3个具体目标。在特定的目标1中，我们将确定能够结合RBP2并建立RBP2的结构特性的非类固醇脂质，从而促进或预防非类固醇配体与RBP2结合。在特定的目标2中，我们将阐明与肠肠上皮细胞中与MAG摄取和代谢有关的RBP2介导的生化途径。在特定的目标3中，我们将在小鼠中调查RBP2在空肠内的作用如何影响代谢表型的发育，以响应不同的高脂饮食的喂养，这些高脂饮食主要由饱和或主要是不饱和脂肪组成的，以及这些饮食如何影响MAG和类似于类动物/类药物/类药物的吸收和吸收性和代谢。