Role of PPARG the PPARG Target Gene RBP7 in the Endothelium

PPARG 的作用 PPARG 靶基因 RBP7 在内皮细胞中的作用

• 批准号: 9249635
• 负责人: Curt Daniel Sigmund
• 金额: $ 61.64万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9249635
• 关键词: Adipose tissue; All-Trans-Retinol; Anti-Inflammatory Agents; Anti-inflammatory; Antioxidants; Aorta; Binding; Biological Assay; Biology; Blood Vessels; CRISPR/Cas technology; Cardiovascular Diseases; Cardiovascular system; Carotid Arteries; Cell Nucleus; Cells; Cellular biology; Cerebrovascular Circulation; Complement; Data; Development; Dominant-Negative Mutation; Endothelial Cells; Endothelium; Exhibits; Family; Functional disorder; Gene Expression; Gene Expression Profiling; Gene Targeting; Genes; Genetic; Genetic Transcription; High Fat Diet; Human; Hypertension; Impairment; Knock-in Mouse; Knock-out; Laboratories; LacZ Genes; Ligand Binding; Ligands; Lipids; Mediating; Molecular; Monitor; Mus; Mutation; Nitric Oxide; Nuclear Translocation; Oxidation-Reduction; Oxidative Stress; PPAR alpha; PPAR delta; PPAR gamma; PPARG gene; Pathway interactions; Phenotype; Physiology; Play; RNA Interference; RXR; Reactive Oxygen Species; Regulation; Reporting; Research Personnel; Retinol Binding Proteins; Risk Factors; Role; Signal Transduction; Stress; Superoxides; Techniques; Testing; Transcriptional Regulation; Transgenic Mice; Vasomotor; adiponectin; basilar artery; cardiovascular risk factor; early onset; efficacy testing; endothelial dysfunction; fatty acid-binding proteins; genome editing; innovation; insulin sensitivity; lipid transport; mutant; novel; overexpression; public health relevance; response; rosiglitazone; selective expression; transcription factor; transcriptome sequencing; vasoconstriction

 DESCRIPTION (provided by applicant): PPARγ is a ligand activated transcription factor best known for its role in regulating insulin sensitivity and adipose tissue development and expansion. There is now convincing evidence to support an important beneficial role for endothelial PPARγ in the regulation of endothelial function. However, little is known about the transcriptional targets for PPARγ, how PPARγ selectively activates some targets over others, and their mechanisms of action in the endothelium. Selective expression of a dominant negative mutant of PPARγ in the endothelium (E-V290M) has no effect on endothelial function in aorta, carotid or basilar arteries in young transgenic mice at baseline, but induces severe dysfunction if the mice are challenged by a high fat diet, Ang-II, or are old. The cerebral circulation is particularly sensitive to oxidative stress in response to the interference with PPARγ signaling. Conversely, increased expression of wildtype PPARγ specifically in the endothelium (E- PPARγ-WT) reduced vasoconstriction to Ang-II. These data strongly suggest that PPARγ plays a protective role in the endothelium under stressed conditions, and the dysfunction resulting from PPARγ impairment is caused by oxidative stress. We identified retinol-binding protein 7 (RBP7) as a PPARγ target gene in the endothelium. RBP7 is an intracellular retinol binding protein belonging to the family of intracellular lipid and fatty acid-binding proteins. Expression of RBP7 is endothelial cell-specific. RBP7-deficient mice exhibit the same high fat diet-induced and Ang-II-induced phenotype as E-V290M mice which selectively express a dominant negative mutant of PPARγ in the endothelium. This led us to consider the innovative concept that the beneficial effects of PPARγ in the endothelium may be mediated by RBP7. Intracellular lipid and fatty acid binding proteins have been reported to bind ligands which activate other ligand activated transcription factors. Thus conceptually, we hypothesize that PPARγ and RBP7 may form a transcriptional regulatory loop (or hub) in endothelial cells, which is required to support an anti oxidant state and when impaired induces a pro-oxidant state. We will examine this concept in two Specific Aims. Specific Aim 1 will test the hypotheses that a) the beneficial effects of wildtype PPARγ over-expression in the endothelium require RBP7, b) that the effects of RBP7 are mediated by its retinol-binding and lipid transport activity, and c) RBP7 is required for the PPARγ- mediated anti-oxidant response, including the expression and function of endothelial adiponectin. Specific Aim 2 will evaluate the molecular mechanisms by which RBP7 regulates PPARγ transcriptional activity by testing the hypothesis that RBP7 with its intrinsic retinol binding and nuclear translocation activity is required for transcriptional activity of PPARγ.

 描述（由适用提供）：PPARγ是配体激活的转录因子，以其在调节胰岛素敏感性和脂肪组织的发育和扩张中的作用而闻名。现在有令人信服的证据支持内皮PPARγ在调节内皮功能中的重要有益作用。然而，关于PPARγ的转录靶标，PPARγ如何选择性地激活其他靶标及其在内皮中的作用机理知之甚少。内皮（E-V290M）中PPARγ的显性负突变体的选择性表达对基线的年轻转基因小鼠的主动脉，颈动脉或基底动脉的内皮功能没有影响，但如果在基线下会诱发严重的功能障碍，如果如果是严重的功能障碍，如果 小鼠受到高脂肪饮食，Ang-II的挑战，或者是旧的。大脑循环对干扰PPARγ信号的干扰特别敏感。相反，在内皮（E-PPARγ-WT）中特异性野生型PPARγ的表达增加可降低血管收缩到ANG-II。这些数据强烈表明，在压力条件下，PPARγ在内皮中起受保护的作用，导致功能障碍。来自PPARγ损伤是由氧化应激引起的。我们将视黄醇结合蛋白7（RBP7）鉴定为原始硫代基因中的PPARγ靶基因。 RBP7是一种属于细胞内脂质和脂肪酸结合蛋白家族的细胞内视黄醇结合蛋白。 RBP7的表达是去核细胞特异性的。 RBP7缺乏的小鼠表现出与E-V290M小鼠相同的高脂肪饮食诱导的和ANG-II诱导的表型，该表型在内皮中有选择地表达PPARγ的显性负突变体。这使我们考虑了一种创新的概念，即PPARγ在内皮中的有益作用可能是由R​​BP7介导的。据报道，细胞内脂质和脂肪酸结合蛋白可以结合配体，该配体激活其他配体激活的转录因子。从概念上讲，我们假设PPARγ和RBP7可能会在内皮细胞中形成转录调节环（或轮毂），这是支持抗抗抗抗的所必需的 氧化态，当受损时会诱导促氧化态。我们将以两个具体的目的研究这个概念。 Specific Aim 1 will test the hypotheses that a) the beneficial effects of wildtype PPARγ over-expression in the endotherium require RBP7, b) that the effects of RBP7 are mediated by its retinol-binding and lipid transport activity, and c) RBP7 is required for the PPARγ- mediated anti-oxidant response, including the expression and function of endothelial adiponectin.具体目标2将评估RBP7通过测试RBP7及其内在的视黄醇结合和核转运活性的假设来调节PPARγ转录活性的分子机制。