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衰老疾病有关，包括心血管疾病、二型糖尿病、非酒精性脂肪性肝炎、多发性硬化症和阿尔茨海默病，而胆固醇升高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。细胞利用负反馈和正前馈控制的组合来协调维持胆固醇稳态。当细胞内胆固醇增加时，编码胆固醇合成所需的酶的基因的表达会受到影响。通过抑制转录因子甾醇调节元件结合蛋白 2 (SREBP2) 的蛋白水解激活来抑制（负反馈）相反，升高的胆固醇通过增加胆固醇的转录活性来诱导编码参与胆固醇排泄的蛋白质的基因表达（正前馈）。肝脏 X 受体 (LXR) 是核激素受体超家族的配体激活转录因子的成员，可响应胆固醇衍生物的直接结合而调节基因表达。为了揭示胆固醇在慢性疾病中的作用，我们建议以细胞类型特异性的方式可逆地破坏胆固醇稳态。为此，我们建议培育一种小鼠品系，该小鼠品系允许组织特异性表达色氨酸 441 突变为苯丙氨酸（W441F）的 LXRα。 W441F 破坏内源性胆固醇衍生的 LXR 配体的结合，同时仍然允许通过有效的合成激动剂进行转录激活，从而提供了一种独特的工具来阻止 LXR 配体的能力。 LXRα 能够感知胆固醇水平的变化，同时仍允许进行药物控制。我们的初步数据表明，LXRα W441F 发挥显性失活作用，可关闭 LXR 内转录活性并促进细胞胆固醇积累。重要的是，可以通过处理表达 LXRα 的细胞来恢复 LXR 活性。因此，我们建议开发一种新型小鼠模型，通过表达 LXRα 来实现胆固醇稳态的时间和空间调节。 W441F 在 Cre 重组酶控制下。