Retinoid Homeostasis

类维生素A稳态

• 批准号: 8948853
• 负责人: JOSEPH L NAPOLI
• 金额: $ 34.49万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8948853
• 关键词: Address; Adipocytes; Adult; Alcoholic Liver Diseases; All-Trans-Retinol; Anabolism; Autacoids; Autocrine Communication; Autophagocytosis; Binding Proteins; Biological; Cardiac development; Cell physiology; Cells; Data; Development; Diabetes Mellitus; Disease; Embryonic Development; Enzyme Kinetics; Enzymes; Esters; Fluorescence Microscopy; Gene Family; Genes; Goals; Hepatocyte; Homeostasis; Inflammation; Isoenzymes; Knock-out; Lecithin; Life; Lipids; Location; Malignant Neoplasms; Mediating; Membrane; Metabolism; Methods; Mitochondria; Molecular; Mus; Muscle; Myopathy; Names; Nature; Nervous System Physiology; Obesity; Organelles; Outcome; Oxidoreductase; Paracrine Communication; Pattern; Phenotype; Process; Proteins; Proteomics; RalDH1; Reaction; Regulation; Research; Retinal; Retinal dehydrogenase; Retinoids; Retinol Binding Proteins; Retinol dehydrogenase; Role; Signaling Molecule; Site; Skeletal Development; Smooth Endoplasmic Reticulum; Source; Surface; Testing; Time; Transferase; Tretinoin; Vitamin A; Vitamin A Deficiency; atherogenesis; base; cell fate specification; cell type; cellular imaging; energy balance; enzyme activity; functional disability; immune function; insight; interest; knock-down; lecithin-retinol acyltransferase; lipid biosynthesis; lipid metabolism; metabolomics; migration; nervous system development; public health relevance; short chain trans-2-enoyl-CoA reductase

 DESCRIPTION (provided by applicant): Biosynthesis of all-trans-retinoic acid (RA) from retinol (vitamin A) produces an autacoid that regulates cell fate specification and functions of differentiated cells, including fuel use, immune function, and nervous system function, to name a few. Multiple retinol dehydrogenases (Rdh) and reductases (RRD) of the short-chain dehydrogenase/reductase gene (SDR) family catalyze conversion of retinol into retinal or retinal into retinol. Three have been knocked out in mice: the dehydrogenases Rdh1 and Rdh10; the reductase Dhrs3. These three knockouts each reveal a vitamin A-deficiency phenotype, associated with adiposity, nervous system development and function, and cardiac and skeletal development, respectively. Each has widespread expression throughout embryogenesis and in the adult. In addition, the retinal reductase Dhrs3 and the retinol dehydrogenase Rdh10 seem to form a facilitative heterodimer. Retinal dehydrogenases (Raldh) catalyze the second step of RA biosynthesis, irreversible conversion of retinal into RA. Knockouts of Raldh1, Raldh2, and Raldh3, show phenotypes reflecting RA deficiency, but each is distinct, involving energy balance, immune function/embryogenesis, and development, respectively. These data suggest that specific metabolons (enzyme combinations, Rdh/RRD/Raldh) generate discrete RA pools to support distinct retinoid functions. Coordinated regulation and function of these putative metabolons have not been examined. The long-term goals of this research are to determine sites of RA biosynthesis, biological impact of each metabolon, and mechanisms of regulating metabolon expression. Virtually all cells, except white adipocytes, form multilocular lipid droplet (LD). LD function as organelles that may generate autacoids. Relatively little research has focused on this potential LD function, however. Before LD biosynthesis, the major retinol esterifying enzyme, lecithin:retinol acyl transferase (LRAT), localizes in the smooth endoplasmic reticulum, as does Rdh1. The major intracellular retinol binding-protein, Crbp1 localizes with mitochondria or mitochondria associated membranes (MAM), as does Rdh10. During LD formation Crpb1, LRAT, Rdh10 and Dhrs3, but not Rdh1, locate at or near surfaces of LD. Association of LRAT and Rdh10 with LD increases their specific enzyme activity. This project will test the hypothesis that LD incorporate a metabolon for activating retinol into RA, which consists of select enzymes and binding-proteins of retinoid homeostasis. The specific aims are: 1) identify enzymes that contribute to retinoid metabolism in LD isolated from hepatocytes; 2) determine subcellular origin(s) of retinoid-metabolizing enzymes that associate with LD and the precise nature of their interactions with LD; 3) determine the retinoid biosynthesizing capacity of LD. This project will generate data significant to retinoid homeostasis, RA biosynthesis, and the function of LD as sources of autacoids, and will provide insight into the role of retinoid metabolism with respect to LD- associated diseases, such as cancer, inflammation, and diabetes.

 描述（由申请人提供）：从视黄醇（维生素A）生物合成全反式视黄酸（RA）产生一种自体素，其调节细胞命运的规范和分化细胞的功能，包括燃料使用、免疫功能和神经系统功能，仅举几例。短链脱氢酶/还原酶基因（SDR）家族的多个视黄醇脱氢酶（Rdh）和还原酶（RRD）催化视黄醇转化为视黄醛或视黄醛转化为视黄醇。其中三种已经在小鼠中被敲除：还原酶Rdh 1和Rdh 10;还原酶Dhrs 3。这三个基因敲除分别揭示了维生素A缺乏表型，分别与肥胖、神经系统发育和功能以及心脏和骨骼发育相关。每一种都在整个胚胎发生和成体中广泛表达。此外，视网膜还原酶Dhrs 3和视黄醇脱氢酶Rdh 10似乎形成了一个促进异二聚体。视网膜色素酶（Raldh）催化RA生物合成的第二步，将视网膜不可逆地转化为RA。Raldh 1、Raldh 2和Raldh 3的敲除显示反映RA缺乏的表型，但每种表型都是不同的，分别涉及能量平衡、免疫功能/胚胎发生和发育。这些数据表明，特定的代谢物（酶组合，Rdh/RRD/Raldh）产生离散的RA池，以支持不同的类维生素A功能。这些假定的代谢子的协调调节和功能尚未被检查。本研究的长期目标是确定RA生物合成的位点，每个代谢子的生物学影响，以及调节代谢子表达的机制。除白色脂肪细胞外，几乎所有细胞都形成多室脂滴（LD）。LD作为细胞器发挥功能，可产生自泌体。然而，相对较少的研究集中在这种潜在的LD功能上。在LD生物合成之前，主要的视黄醇还原酶卵磷脂：视黄醇酰基转移酶（LRAT）定位于滑面内质网，Rdh 1也是如此。主要的细胞内视黄醇结合蛋白，Crbp 1定位于线粒体或线粒体相关膜（MAM），如Rdh 10。在LD形成过程中，Crpb 1、LRAT、Rdh 10和Dhrs 3位于LD表面或附近，而Rdh 1不位于LD表面或附近。LRAT和Rdh 10与LD的结合增加了它们的比酶活性。本项目将验证LD将激活视黄醇的代谢子纳入RA的假设，该代谢子由选择的类维生素A稳态的酶和结合蛋白组成。具体目标是：1）鉴定在从肝细胞分离的LD中有助于类维生素A代谢的酶; 2）确定与LD相关的类维生素A代谢酶的亚细胞来源及其与LD相互作用的精确性质; 3）确定LD的类维生素A生物合成能力。 LD.该项目将产生对类维生素A体内平衡、RA生物合成和LD作为自体激素来源的功能具有重要意义的数据，并将提供对类维生素A代谢在LD相关疾病（如癌症、炎症和糖尿病）中的作用的深入了解。