Role of FoxOs in Skeletal Homeostasis

FoxOs 在骨骼稳态中的作用

基本信息

批准号：
8634019
负责人：
Maria Jose Almeida
金额：
$ 30.69万
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/8634019
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.

描述（由申请人提供）：Wnt/2-连环蛋白信号传导对于成骨细胞发生和骨形成是不可或缺的。在导致该应用的研究中，阐明了 Wnt/2-连环蛋白拮抗作用的新机制，即 FoxO 转录因子的激活将有限的 2-连环蛋白池从 Wnt 诱导的 TCF/Lef 转录转移到 FoxO 介导的转录。骨中的这种拮抗级联是由活性氧 (ROS) 引发的，既是氧化应激的介体，又是氧化应激的防御机制。 FoxOs 通过调节参与细胞周期、DNA 修复和寿命的基因表达来介导氧化应激反应。组蛋白脱乙酰酶 Sirt1 参与 ROS 对 Wnt/2-catenin 的抑制；并且还建立了2-连环蛋白共激活FoxO靶基因的表达，从而促进成骨细胞在应激条件下的存活。此外，有证据表明糖皮质激素或 TNF1 对骨的作用至少部分是由 ROS 诱导的 FoxO 激活介导的。上述观察结果构成了以下假设的基础：氧化应激激活 FoxO 转录因子代表了一种以前未被认识到的 Wnt/2-catenin 拮抗细胞自主机制，该机制导致衰老、糖皮质激素过量和炎症细胞因子对骨骼的不利影响。通过将 2-连环蛋白从 TCF 介导的转录转移到 FoxO 介导的转录。为了检验这一假设，ROS 诱导的 FoxO 翻译后修饰对成骨细胞中 FoxO 与 2-catenin 结合的作用，以及 ROS 是否导致 2-catenin 募集到 FoxO 靶基因的启动子将被研究。进行调查（目标 1）。此外，还将进行体外研究以确定 FoxO 激活对成骨细胞寿命和分化的影响（目标 2）。最后，在成骨细胞前体及其后代（成骨细胞、骨细胞）中过度表达 FoxO3a 的小鼠；条件性删除三种主要 FoxO 同工型 FoxO1、3a 和 4 的小鼠将用于检查 FoxO 在骨骼稳态中的作用（目标 3）。这项工作应该增进人们对衰老、糖皮质激素过量或炎症细胞因子如何减少骨量的了解。此外，它应该可以让人们更好地了解如何优化这种情况的治疗。