Tissue Specific Control of Cholesterol Metabolism

胆固醇代谢的组织特异性控制

基本信息

批准号：
10653100
负责人：
Ira G Schulman
金额：
$ 20.19万
依托单位：
UNIVERSITY OF VIRGINIA
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-07-01 至 2025-04-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10653100
关键词：
Aging Agonist Alzheimer&apos s Disease Animals Anti-Inflammatory Agents Atherosclerosis Binding Cardiovascular Diseases Cells Cholesterol Cholesterol Homeostasis Chronic Disease Clustered Regularly Interspaced Short Palindromic Repeats Data Dependovirus Development Diet Disease Dominant-Negative Mutation Elements Enterobacteria phage P1 Cre recombinase Enzymes Excretory function Exposure to Fatty Liver Feces Feedback Gene Expression Generations Genetic Transcription Goals Heart Diseases Hepatocyte Heterozygote Homeostasis Human Impairment Individual LXRalpha protein Life Ligands Link Liver Liver X Receptor Location LoxP-flanked allele Macrophage Modeling Multiple Sclerosis Mus Mutation Myeloid Cells Non-Insulin-Dependent Diabetes Mellitus Nuclear Hormone Receptors Pathologic Pathology Pathway interactions Phenotype Phenylalanine Play Process Proteins Regulation Repression Research Personnel Role SRE-2 binding protein Testing Time Tissues Transcriptional Activation Tryptophan cell type cholesterol control lipid metabolism member mouse model new therapeutic target next generation nonalcoholic steatohepatitis novel pharmacologic programs promoter response reverse cholesterol transport selective expression tool transcription factor transcription termination uptake

项目摘要

Alterations in cholesterol metabolism are often associated with chronic diseases of aging including cardiovascular disease, type II diabetes, non-alcoholic steatohepatitis, multiple sclerosis, and Alzheimer’s disease. While elevated cholesterol is linked to many chronic diseases, in most cases the cholesterol-dependent pathways that drive pathological changes in function have not been well described. Cells use a combination of negative feedback and positive feed forward control to coordinately maintain cholesterol homeostasis. When intracellular cholesterol increases, expression of genes encoding enzymes required for cholesterol synthesis is repressed (negative feedback) by inhibiting the proteolytic activation of the transcription factor sterol regulatory element binding protein 2 (SREBP2). In contrast, elevated cholesterol induces expression of genes encoding proteins involved in cholesterol excretion (positive feed forward) by increasing the transcriptional activity of the liver x receptors (LXRs). The LXRs are members of the nuclear hormone receptor superfamily of ligand activated transcription factors that regulate gene expression in response to the direct binding of cholesterol derivatives. We suggest that a unique approach to unraveling the roles of cholesterol in chronic diseases will be to reversibly disrupt cholesterol homeostasis in a cell type specific manner. To this end we propose to generate a mouse line that allows tissue specific expression of LXRα with a mutation of tryptophan 441 to phenylalanine (W441F). W441F disrupts binding of endogenous cholesterol-derived LXR ligands while still allowing transcription activation by potent synthetic agonists providing a unique tool that blocks the ability of LXRα to sense changes in cholesterol levels while still allowing pharmacological control. Our preliminary data indicates that LXRα W441F functions as a dominant negative that shuts down LXR transcriptional activity and promotes intracellular cholesterol accumulation. Importantly, LXR activity can be restored by treating cells expressing LXRα W441F with synthetic LXR agonists. Therefore, we propose to develop a novel mouse model that allows temporal and spatial regulation of cholesterol homeostasis by expressing LXRα W441F under Cre recombinase control.

胆固醇代谢的改变通常与慢性疾病有关，包括心血管疾病，II型糖尿病，非酒精性脂肪性肝炎，多发性硬化症和阿尔茨海默氏病。尽管升高的胆固醇与许多慢性疾病有关，但在大多数情况下，胆固醇依赖性途径驱动功能的病理变化的途径尚未得到很好的描述。细胞结合负反馈和阳性反馈前向控制来协调维持胆固醇稳态。当细胞内胆固醇增加时，通过抑制转录因子固醇调节元素结合蛋白2（SREBP2）的蛋白水解活化来反映胆固醇合成所需的酶的基因表达（负反馈）。相反，升高的胆固醇通过增加肝X受体（LXR）的转录活性来诱导涉及参与胆固醇排泄的蛋白（正向前馈）的基因表达。 LXR是配体激活转录因子超家族的成员，这些转录因子对胆固醇衍生物的直接结合而调节基因表达。我们建议，一种独特的方法来阐明胆固醇在慢性疾病中的作用是以特定于细胞类型的方式可逆地破坏胆固醇的稳态。为此，我们建议生成一条小鼠系，该系列允许使用色氨酸441突变为苯丙氨酸（W441F）的LXRα的组织特异性表达。 W441F破坏了内源性胆固醇衍生的LXR配体的结合，同时仍允许通过潜在的合成激动剂进行转录激活，从而提供了一种独特的工具，该工具可以阻止LXRα感知胆固醇水平的变化，同时仍允许药物控制。我们的初步数据表明，LXRαW441F的作用是关闭LXR转录活性并促进细胞内胆固醇积累的主要负阴性。重要的是，可以通过使用合成LXR激动剂来处理表达LXRαW441F的细胞来恢复LXR活性。因此，我们建议开发一种新型的小鼠模型，该模型可以通过在CRE重组酶控制下表达LXRαW441F来暂时和空间调节胆固醇稳态。