Role of FoxOs in Skeletal Homeostasis

FoxOs 在骨骼稳态中的作用

基本信息

批准号：
8225401
负责人：
Maria Jose Almeida
金额：
$ 31.32万
依托单位：
UNIV OF ARKANSAS FOR MED SCIS
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-04-15 至 2015-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8225401
关键词：
Acetylation Adult Adverse effects Affect Aging Antioxidants Apoptosis Binding Biological Assay Bone remodeling Cell Cycle Cell Death Cell Line Cell Respiration Cells DNA Repair DNA Repair Enzymes DNA lesion Defense Mechanisms Electron Transport Enzymes Family Foundations Free Radical Scavenging Gene Expression Gene Targeting Generations Genes Genetic Transcription Glucocorticoids Health Histone Deacetylase Homeostasis Immunoprecipitation In Vitro Inflammatory Interferons Knowledge Lead Lipid Peroxidation Longevity Mediating Mediator of activation protein Mitochondria Modeling Mus Osteoblasts Osteoclasts Osteocytes Osteogenesis Oxidative Stress Peroxides Phenotype Phosphorylation Play Post-Translational Protein Processing Prevalence Protein Isoforms Proteins Reactive Oxygen Species Risk Role Signal Transduction Signaling Molecule Site Stem cells Stress Testing Transgenes Vertebral Bone Work age related base biological adaptation to stress bone bone loss bone mass bone strength catalase chromatin immunoprecipitation cytokine in vivo mutant novel osteoblast differentiation osteoclastogenesis osteoporosis with pathological fracture overexpression prevent progenitor promoter protein function public health relevance recombinase skeletal therapy development transcription factor

项目摘要

DESCRIPTION (provided by applicant): Wnt/2-catenin signaling is indispensable for osteoblastogenesis and bone formation. In studies leading to this application, a novel mechanism of Wnt/2-catenin antagonism, whereby activation of FoxO transcription factors diverts the limited pool of 2-catenin from Wnt induced TCF/Lef- transcription to FoxO-mediated transcription was elucidated. This antagonistic cascade in bone is initiated by reactive oxygen species (ROS) and represents both a mediator of, and a defense mechanism against, oxidative stress. FoxOs mediate oxidative stress responses by regulating the expression of genes involved in cell cycle, DNA repair, and lifespan. The involvement of the histone deacetylase Sirt1 in the inhibition of Wnt/2-catenin by ROS; and co- activation by 2-catenin of the expression of FoxO-target genes that promote osteoblast survival under stress conditions was also established. Moreover, evidence was obtained that the actions of glucocorticoids or TNF1 on bone are mediated, at least in part, by ROS-induced FoxO activation. The above observations form the foundation of the hypothesis that activation of FoxO transcription factors by oxidative stress represents a previously unappreciated cell-autonomous mechanism of Wnt/2-catenin antagonism which contributes to the adverse effects of aging, glucocorticoid excess and inflammatory cytokines on bone, by diverting 2-catenin from TCF- to FoxO-mediated transcription. To test this hypothesis, the role of ROS-induced FoxO post- translational modifications on the binding of FoxOs to 2-catenin, in osteoblastic cells, and whether ROS lead to recruitment of 2-catenin to the promoter of FoxO-target genes will be investigated (Aim 1). In addition, in vitro studies will be done to establish the consequences of FoxO activation in osteoblast lifespan and differentiation (Aim 2). Finally, mice overexpressing FoxO3a in osteoblast precursors and their progeny (osteoblasts, osteocytes); and mice in which the three main FoxO isoforms FoxO1, 3a, and 4 are conditionally deleted will be used to examine the role of FoxOs in skeletal homeostasis (Aim 3). This work should advance knowledge of how aging, glucocorticoid excess or inflammatory cytokines decrease bone mass. Furthermore, it should provide a better understanding of how to optimize the treatment of this condition. PUBLIC HEALTH RELEVANCE: The proposed studies seek to identify the means by which aging, glucocorticoid excess or inflammatory cytokines cause bone loss. This will be accomplished by studying changes in the function of proteins that control bone-forming cells. Increased understanding of the mechanisms that control bone formation will provide important information for the development of therapies to maintain or increase bone mass and strength, thereby reducing the risk of osteoporotic fractures

描述（由申请人提供）：Wnt/2-catenin信号传导对于成骨细胞生成和骨形成是必不可少的。在导致该应用的研究中，Wnt/2-catenin拮抗作用的一种新型机制，从WNT诱导的TCF/LEF-转录转移到FOXO介导的转录转录的有限库中，将FOXO转录因子的激活转移到了有限的2-catenin池。这种骨骼中的拮抗级联反应是由活性氧（ROS）引发的，既代表了氧化应激的介体，也代表了防御机制。 FOXOS通过调节与细胞周期，DNA修复和寿命有关的基因的表达来介导氧化应激反应。组蛋白脱乙酰基酶SIRT1参与ROS抑制Wnt/2-catenin；还建立了在应激条件下促进成骨细胞存活的Foxo-target基因表达的2-catenin的共同激活。此外，还获得了证据表明，糖皮质激素或TNF1对骨骼的作用至少部分是通过ROS诱导的FOXO激活介导的。 The above observations form the foundation of the hypothesis that activation of FoxO transcription factors by oxidative stress represents a previously unappreciated cell-autonomous mechanism of Wnt/2-catenin antagonism which contributes to the adverse effects of aging, glucocorticoid excess and inflammatory cytokines on bone, by diverting 2-catenin from TCF- to FoxO-mediated transcription.为了检验这一假设，ROS诱导的FOXO转化后修饰在成骨细胞中对FoxOS与2-catenin结合的作用，以及ROS是否导致2-catenin向Foxo-Target基因的启动子募集（AIM 1）。此外，将进行体外研究以确定成骨细胞寿命和分化中FoxO激活的后果（AIM 2）。最后，在成骨细胞前体及其后代（成骨细胞，骨细胞）中过表达FOXO3A的小鼠；有条件删除的三个主要FOXO同工型FoxO1、3A和4的小鼠将用于检查FoxOS在骨骼稳态中的作用（AIM 3）。这项工作应提高人们对衰老，糖皮质激素过量或炎性细胞因子如何减少骨骼量的知识。此外，它应该更好地理解如何优化这种情况的处理。公共卫生相关性：拟议的研究旨在确定衰老，糖皮质激素过量或炎性细胞因子导致骨质流失的手段。这将通过研究控制骨形成细胞的蛋白质功能的变化来实现。对控制骨骼形成的机制的了解将增加为发展或增加骨骼质量和力量的疗法提供重要信息，从而降低骨质疏松性骨折的风险