Ahr and Osteoporosis

Ahr 和骨质疏松症

基本信息

批准号：
9298591
负责人：
NARAYAN G AVADHANI
金额：
$ 65.47万
依托单位：
ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-07-01 至 2019-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9298591
关键词：
AHR gene Agonist Aromatic Polycyclic Hydrocarbons Aryl Hydrocarbon Receptor Benzo(a)pyrene Biological Assay Bone Marrow Cells Bone Resorption CCAAT-enhancer-binding protein-delta CREB1 gene Cell Nucleus Cells Chemicals Chronic Cigarette Cigarette Smoker Clinical Cytochrome P450 Data Dioxins Enzymes Event Excision F2-Isoprostanes Fracture Gene Expression Genes Genetic Transcription Hydrogen Peroxide Hypoxia Joints Knock-in Mouse Location Marrow Mediating Mediator of activation protein Microsomes Mitochondria Molecular Mus Osteoblasts Osteoclasts Osteocytes Osteogenesis Osteoporosis Oxidative Stress Pathway interactions Pharmacology Phenotype Play Polychlorinated Biphenyls Production Proteins Reactive Oxygen Species Receptor Activation Reporter Risk Role Signal Transduction Skeleton Small Interfering RNA Smoke Smoker Smoking Stress Testing Tetrachlorodibenzodioxin Toxin bone bone cell bone loss bone mass calcineurin phosphatase cell type cigarette smoking cytokine dentin matrix protein 1 high risk inhibitor/antagonist innovation metabolic phenotype mouse model multidisciplinary mutant osteoclastogenesis oxidative damage promoter public health relevance response skeletal therapeutic target

项目摘要

DESCRIPTION (provided by applicant): Cigarette smokers suffer from severe osteoporosis, and are therefore at an exceptionally high risk of skeletal fracture. However, the mechanism through which smoke causes bone loss remains unclear. We find that BaP (benzo[a]pyrene) and TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), two of over 200 known chemicals found in cigarette smoke, trigger the aryl hydrocarbon receptor (Ahr) and the cytochrome P450 (Cyp1) enzymes to stimulate bone removal. Despite these observations, several gaps in our understanding remain. First, we are uncertain which bone cell, osteoclast, osteoblast or osteocyte, primarily mediates this action. Therefore, in Specific Aim 1, we will study the bone phenotype of mice in which the Ahr gene is deleted selectively in each cell type, and then examine the effect of the Ahr agonists BaP and TCDD on skeletal mass and remodeling. Second, we are unclear whether the osteoclast-stimulatory action of Ahr agonists involves the activation of mitochondrial or microsomal Cyp1s, and whether the reactive oxygen species (ROS) so produced mediate this action. Therefore, in Specific Aim 2, we will administer BaP and/or TCDD to knock-in mice expressing Cyp1 proteins either in mitochondria or in microsomes. We will phenotype their skeletons and study ROS production in isolated bone marrow cells. Our previous studies have further shown that ROS activate mitochondria-to-nucleus signals to generate a pro-osteoclastogenic footprint comprising CREB, C/EBPδ, NF-κB, NFAT2, and hnRNPA2. In Specific Aim 3, we will determine whether this transcriptional footprint is activated by Ahr agonists. If so, we will utilize siRNA and/or chemical inhibitors to validate the role of each molecule, as well as promoter-reporter assays and ChIP to confirm that the footprint transactivates osteoclast gene expression. These studies should establish the Ahr as a therapeutic target for osteoporosis and unravel, at least to an extent, the molecular basis underlying the osteoporosis noted in smokers.

描述（由适用提供）：吸烟者患有严重的骨质疏松症，因此骨骼骨折的风险异常高。但是，烟雾导致骨质流失的机制尚不清楚。我们发现BAP（Benzo [a] pyrene）和TCDD（2,3,7,8-四氯迪本佐-P-二恶英），在香烟烟雾中发现的200多种已知化学物质中的两种，触发了芳基烃受体（AHR）和细胞色素P450（CYP1）Enzymes刺激骨骼骨骼的蛋白含量。尽管有这些观察，我们的理解仍然存在几个差距。首先，我们不确定哪种骨细胞，破骨细胞，成骨细胞或骨细胞介导了这种作用。因此，在特定的目标1中，我们将研究在每种细胞类型中选择性删除AHR基因的小鼠的骨表型，然后检查AHR激动剂BAP和TCDD对骨骼质量和重塑的影响。其次，我们尚不清楚AHR激动剂的破骨细胞刺激作用是否涉及线粒体或微粒体CYP1的激活，以及反应性氧（ROS）是否介导了这种作用。因此，在特定的目标2中，我们将对线粒体或微粒体中表达CYP1蛋白的敲击小鼠进行BAP和/或TCDD。我们将表型表型并研究分离的骨髓细胞中的ROS产生。我们先前的研究进一步表明，ROS激活线粒体到核信号，以产生促层层造型的足迹，其中包括CREB，C/EBPδ，NF-κB，NFAT2和HNRNPA2。在特定的目标3中，我们将确定该转录足迹是否由AHR激动剂激活。如果是这样，我们将利用siRNA和/或化学抑制剂来验证每个分子的作用，以及启动子 - 重复蛋白测定和芯片，以确认足迹反式反式激活破骨细胞基因表达。这些研究应确定AHR作为骨质疏松症和脱离的治疗靶标，至少在一定程度上是吸烟者中指出的骨质疏松症的分子基础。