Molecular Components Affecting Ocular Retinoid Homeostasis

影响眼部视黄醇稳态的分子成分

• 批准号: 7696119
• 负责人: Johannes Friedrich von Lintig
• 金额: $ 39.25万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7696119
• 关键词: 11 cis Retinal; Address; Affect; All-Trans-Retinol; Animal Model; Binding; Binding Proteins; Biochemical; Biochemistry; Biology; Blood; Carotene; Carotenoids; Cell Culture Techniques; Cell Differentiation process; Cell Line; Clinical; Data; Development; Diet; Disease; Dissection; Elements; Enzymes; Epithelial; Eye; Eye Development; G-Protein-Coupled Receptors; Gatekeeping; Gene Expression Regulation; Genes; Genetic; Health; Homeobox; Homeostasis; Human; Immunity; Intestinal Absorption; Intestines; Knock-out; Knockout Mice; Knowledge; Ligands; Lipids; Mammals; Mediating; Membrane Proteins; Metabolic; Metabolic Control; Metabolism; Molecular; Mouse Strains; Mus; Mutant Strains Mice; Mutation; Non-Insulin-Dependent Diabetes Mellitus; Nuclear Receptors; Oxygenases; Pathologic Processes; Pathology; Pathway interactions; Play; Prevention; Process; Production; Proteins; Receptor Signaling; Regulation; Reporter; Reporter Genes; Research; Retinoic Acid Receptor; Retinoids; Retinol Binding Proteins; Role; Serum; Testing; Tissues; Tretinoin; Vision; Visual; Vitamin A; Vitamins; Woods syndrome; Work; Zebrafish; absorption; base; chromophore; embryo tissue; human disease; improved; in vivo; insight; interest; malformation; metabolic abnormality assessment; mouse model; prevent; promoter; public health relevance; scavenger receptor; transcription factor; uptake

DESCRIPTION (provided by applicant): The essential role of vitamin A for the vertebrate eye has long been known because deficiency in or excess of this vitamin can impair eye development and function. Vitamin A is the precursor for at least two critical metabolites, 11-cis-retinal, the chromophore of visual G-protein-coupled receptors, and retinoic acid, a ligand for nuclear receptors. Since retinoids cannot be synthesized de novo by humans, dietary precursors must be absorbed by the intestine and metabolically converted. The converted retinoids must then be transported within the body for storage and delivered to target tissues such as the eyes. This process evidently depends on specific transporters and binding proteins. These components have recently attracted broad scientific and clinical interest since they are associated with diseases as diverse as type 2 diabetes and the fatal Matthew-Wood syndrome. Yet our knowledge of the pathology of these diseases is scant due to a lack of studies in homologous mammalian animal models. Such study would contribute to our understanding of the biochemistry of vitamin A transport as well as the regulatory mechanisms that govern retinoid homeostasis. The long-term objective of the proposed studies is to analyze two key steps affecting ocular retinoid metabolism: the intestinal absorption and metabolic conversion of ¿,¿-carotene to retinol and the uptake of ¿,¿-carotene-derived retinol into the eyes. In Aim 1, we will address the role of the intestine specific homeobox transcription factor ISX that suppresses Srb1 and Bcmo1 gene activities which respectively encode a carotenoid transporter and the key enzyme for ¿,¿-carotene conversion into retinoids. By genetic dissection, we will analyze the molecular basis of ¿,¿-carotene absorption and conversion into retinoids and the regulation of this pathway. For this purpose, we will study ¿,¿-carotene metabolism and retinoid homeostasis in Isx, Srb1 and Bcmo1 single and compound knockout mice. Promoter/reporter gene studies will be performed to elucidate the molecular details of this regulation including the role of retinoic acid in this process. In Aim 2, we will establish knockout mice lacking STRA6 (stimulated by retinoic acid 6) protein to study the metabolic basis of the fatal Matthew-Wood syndrome. We also will generate compound knockouts lacking both STRA6 and the serum retinol binding protein 4 (RBP4) to test for the hypothesis that RBP4 triggers the pathological alterations seen in STRA6-deficiency. Furthermore, we will analyze the role retinoic acid in regulating blood retinol homeostasis in the different mouse mutants. These studies will provide new insights into retinoid metabolism and the control of retinoid homeostasis which will improve understanding of human disease states caused by disturbances in this process and may provide concepts for their prevention and/or therapy. PUBLIC HEALTH RELEVANCE: Retinoids (vitamin A and its derivatives) play an essential role for eye development and function. Ocular retinoid uptake is a homeostatic process that evidently depends on specific transporters and binding proteins. These components have recently attracted broad scientific and clinical interest since they are associated with diseases including the fatal Matthew-Wood syndrome. Yet our knowledge of the underlying pathological processes is scant due to a lack of studies in homologous animal models. Therefore, the long-term objective of our research is to elucidate the pathway for ocular retinoid homeostasis by genetic dissection in mouse models. This information will improve understanding of human disease states caused by disturbances in retinoid homeostasis and may provide concepts for their prevention and/or therapy.

描述（由申请人提供）：维生素A对脊椎动物眼睛的重要作用早已为人所知，因为缺乏或过量这种维生素会损害眼睛的发育和功能。维生素A是至少两种关键代谢物的前体，11-顺式视网膜，视觉g蛋白偶联受体的发色团，视黄酸，核受体的配体。由于类维生素a不能由人类从头合成，饮食中的前体必须被肠道吸收并进行代谢转化。转化后的类维生素a必须在体内运输储存，并运送到目标组织，如眼睛。这一过程显然依赖于特定的转运蛋白和结合蛋白。这些成分最近引起了广泛的科学和临床兴趣，因为它们与2型糖尿病和致命的马修-伍德综合征等多种疾病有关。然而，由于缺乏对同源哺乳动物模型的研究，我们对这些疾病的病理学认识不足。这样的研究将有助于我们对维生素A运输的生物化学以及控制类视黄醇稳态的调节机制的理解。拟议研究的长期目标是分析影响眼部类视黄醇代谢的两个关键步骤：肠道吸收和代谢转化-胡萝卜素为视黄醇，以及-胡萝卜素衍生的视黄醇进入眼睛的摄取。在Aim 1中，我们将讨论肠特异性同源盒转录因子ISX的作用，ISX抑制Srb1和Bcmo1基因活性，这两个基因分别编码类胡萝卜素转运蛋白和将胡萝卜素转化为类维生素a的关键酶。通过基因解剖，我们将分析胡萝卜素吸收和转化为类维生素a的分子基础以及这一途径的调控。为此，我们将研究Isx、Srb1和Bcmo1单敲除和复合敲除小鼠的胡萝卜素代谢和类维生素a稳态。启动子/报告基因研究将用于阐明这一调控的分子细节，包括维甲酸在这一过程中的作用。在Aim 2中，我们将建立缺乏STRA6（由视黄酸6刺激）蛋白的敲除小鼠，以研究致命的Matthew-Wood综合征的代谢基础。我们还将产生缺乏STRA6和血清视黄醇结合蛋白4 （RBP4）的复合敲除，以测试RBP4触发STRA6缺乏症中所见的病理改变的假设。此外，我们将分析维甲酸在不同小鼠突变体中调节血液视黄醇稳态的作用。这些研究将为类视黄醇代谢和控制类视黄醇稳态提供新的见解，从而提高对这一过程中干扰引起的人类疾病状态的理解，并可能为其预防和/或治疗提供概念。公共卫生相关性：类维生素A（维生素A及其衍生物）对眼睛发育和功能起着至关重要的作用。眼内类维甲酸摄取是一个稳态过程，明显依赖于特定的转运体和结合蛋白。这些成分最近引起了广泛的科学和临床兴趣，因为它们与包括致命的马修-伍德综合征在内的疾病有关。然而，由于缺乏对同源动物模型的研究，我们对潜在病理过程的了解不足。因此，我们研究的长期目标是通过小鼠模型的遗传解剖来阐明眼类视黄醇稳态的途径。这一信息将提高对类维生素a体内平衡紊乱引起的人类疾病状态的理解，并可能为其预防和/或治疗提供概念。