Regulation of vitamin A metabolism in the eye

眼内维生素A代谢的调节

• 批准号: 8894008
• 负责人: Marcin Bernard Golczak
• 金额: $ 38.83万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8894008
• 关键词: 11 cis Retinal; Active Sites; Acyltransferase; All-Trans-Retinol; Amino Acids; Architecture; Binding; Binding Proteins; Binding Sites; Biochemical; Biochemistry; Biological Assay; Blindness; Chemicals; Chimeric Proteins; Clinical; Collection; Comparative Biochemistry; Crystallization; Data; Development; Diet; Drug Delivery Systems; Drug Kinetics; Enzymes; Esterification; Esters; Evolution; Exclusion; Eye; Eye diseases; G-Protein-Coupled Receptors; Genes; Health; Homeostasis; Human; Knowledge; Lecithin; Ligands; Location; Metabolic; Metabolism; Methodology; Molecular; Mutate; Mutation; Natural regeneration; Nuclear Receptors; Pathology; Phospholipids; Physiological; Positioning Attribute; Prevention; Process; Production; Protein Family; Proteins; RPE65 protein; Regulation; Research; Retinal; Retinal Degeneration; Retinoids; Role; Specificity; Stargardt' s disease; Structure; Substrate Specificity; Testing; Therapeutic Agents; Time; Tissues; Toxic effect; Tretinoin; Vertebrate Biology; Vision; Visual; Vitamin A; Water; absorption; acyl group; attenuation; base; chromophore; design; improved; interest; lecithin-retinol acyltransferase; novel; novel therapeutics; therapeutic target; thioester; uptake

DESCRIPTION (provided by applicant): Vitamin A is the precursor of at least two critical metabolites in vertebrate biology, 11-cis-retinal, the visual chromophore and retinoic acid, a ligand for nuclear receptors. Absorption of dietary vitamin A and its uptake by targeted body tissues depends on specialized binding proteins, transporters, and enzymes. Key components of the involved metabolic machinery are lecithin: retinol acyltransferase (LRAT), an enzyme that catalyzes the formation of retinyl esters. The physiological role of LRAT has attracted scientific and clinical interest because this enzyme is essential for maintaining systemic vitamin A homeostasis and regenerating visual chromophore. LRAT is also attractive targets for the development of a tissue-specific drug delivery system. Yet, progress in understanding the biochemistry of vitamin A uptake and homeostasis is hindered by a shortage of data regarding the molecular basis of these processes. We have a longstanding research interest focused on understanding LRAT's catalytic and physiological action as well as a mechanism that governs cellular retinoid uptake. Through this application, we propose to elucidate the fundamental molecular mechanism of vitamin A processing by LRAT. In Aim 1, we will delineate the molecular adaptations that discriminate LRAT from related enzymes to confer its vitamin A specificity. We also will identify the LRAT-specific retinoid binding domain and key residues involved in the substrate-protein interaction. Specific Aim 2 will focus on determining the molecular mechanism for LRAT's acyltransferase activity. By solving and analyzing crystal structures of HRASLS/LRAT chimeric proteins, we will discover the critical molecular adaptations that led to the acquisition of acyltransferase activity. We will define these changes at several levels, including the general topology of the enzyme, adjustments of the phospholipid binding mode, and the mechanism of water exclusion from the enzyme's active site. Finally, in specific Aim 3, we will examine the retinoid specificity of the enzyme. We will analyze the structures of the chimeric enzymes in their retinoid-bound states to obtain detailed information regarding the exact location and organization of the vitamin A binding site. Together, these studies will contribute novel and comprehensive knowledge, filling the gap in our understanding of the vitamin A metabolism and production of the visual chromophore. Dissecting molecular mechanisms underlying retinoid esterification will pave the way for more efficient treatment of human retinal degenerative diseases.

描述（由申请人提供）：维生素A是脊椎动物生物学中至少两个关键代谢产物的前体，11- Cis-视网网，视觉发色团和视黄酸，这是一种用于核受体的配体。饮食中维生素A及其吸收的吸收靶向身体组织取决于特殊的结合蛋白，转运蛋白和酶。所涉及的代谢机械的关键成分是卵磷脂：视黄醇酰基转移酶（LRAT），这是一种催化视丁酯的形成的酶。 LRAT的生理作用引起了科学和临床的兴趣，因为该酶对于维持全身性维生素A稳态和再生视觉发色团至关重要。 LRAT也是组织特异性药物输送系统开发的有吸引力的目标。然而，了解维生素A摄取和稳态的生物化学的进展受到有关这些过程的分子基础的数据的不足。我们有一个长期的研究兴趣，重点是理解LRAT的催化和生理作用，以及控制细胞性类维生素性摄取的机制。通过这种应用，我们建议阐明LRAT加工维生素A加工的基本分子机制。在AIM 1中，我们将描述从相关酶区分LRAT的分子适应性，以赋予其特异性维生素A。我们还将确定LRAT特异性类维生素类似结合结构域和与底物 - 蛋​​白质相互作用有关的关键残基。具体目标2将集中于确定LRAT酰基转移酶活性的分子机制。通过求解和分析HRASLS/LRAT嵌合蛋白的晶体结构，我们将发现导致酰基转移酶活性获得的关键分子适应性。我们将在几个级别上定义这些变化，包括酶的一般拓扑，磷脂结合模式的调整以及水排除在酶的活性位点之外的机理。最后，在特定的目标3中，我们将检查酶的类视黄素特异性。我们将分析其视网膜类似状态中嵌合酶的结构，以获取有关维生素A结合位点的确切位置和组织的详细信息。这些研究将共同​​有助于新颖而全面的知识，从而填补了我们对维生素A代谢和视觉发色团产生的差距。剖析视视视网麻酯酯化的基于分子机制将为人类视网膜退行性疾病的更有效治疗铺平道路。