Different consequences of cellular aging in cortical versus cancellous bone- Resubmission

皮质骨与松质骨细胞老化的不同后果 - Resubmission

基本信息

批准号：
10380903
负责人：
Maria Jose Almeida
金额：
$ 38.36万
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：
2021
资助国家：
美国
起止时间：
2021-04-01 至 2025-12-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10380903
关键词：
Adipocytes Age Age-Related Bone Loss Aging Apoptosis Attenuated Bone Marrow Bone Resorption Bone remodeling CDKN1A gene CDKN2A gene Cell Aging Cell Cycle Arrest Cell Cycle Regulation Cell Lineage Cells DNA Damage Disease Exhibits Fracture GATA4 gene Human In Vitro Inflammatory Knowledge Label Laboratories Molecular Mus NF-kappa B Organ Culture Techniques Osteoblasts Osteocytes Osteogenesis Osteoporosis Oxidative Stress Pathway interactions Pharmacology Phenotype Porosity Production Resistance SOD2 gene Skeleton TNFSF11 gene TP53 gene Testing Thinness Time Tissues Transgenes Transgenic Organisms Up-Regulation Vertebral column Woman Work age related aged base bone bone loss bone mass cell type cortical bone cytokine fragility fracture functional decline human old age (65+)inhibitor long bone loss of function men osteoprogenitor cell overexpression prevent progenitor red fluorescent protein response senescence skeletal substantia spongiosa therapy development young adult

项目摘要

Project Summary/Abstract Aging is responsible for the majority of fractures in both women and men. The cellular changes in the skeleton of aged mice are similar to those observed in aged humans. In mice, trabecular bone loss is associated with low bone remodeling, while cortical thinning and porosity are associated with high bone remodeling. These findings suggest that different molecular mechanisms underlie the bone loss in these two compartments. Cellular senescence contributes to the functional decline of multiple tissues with age and DNA damage is a major cause of senescence. DNA damage causes senescence via activation of p53 and up-regulation of the cell cycle inhibitor p21 and/or p16. DNA damage also causes accumulation of the transcription factor GATA4, which promotes the senescence associated secretory phenotype (SASP). Systemic clearance of senescent cells delays several age- associated disorders and increases bone mass in old mice. We have shown that the number of osteoprogenitors in murine bone marrow declines with age and that these cells have increased markers of senescence. Cortical osteocytes also exhibit increased markers of senescence in aged mice and this is associated with elevated production of RANKL. Induction of senescence in bone organ cultures by DNA damage is sufficient to increase GATA4 and RANKL production. Moreover, overexpression of GATA4 in vitro is sufficient to increase RANKL and other components of the SASP. Administration of senolytics to old mice attenuates markers of senescence in osteoprogenitors and osteocytes. Notably, mice lacking RANKL in osteocytes are protected from the loss of cortical but not trabecular bone with age. We hypothesize that activation of p53/p21 in osteoprogenitors causes their senescence and thereby decreases osteoblast number and bone formation and that accumulation of senescent osteocytes in cortical, but not trabecular, bone increases RANKL and bone resorption via GATA4 stimulation. In Aim 1 we will determine whether DNA damage in osteoblast lineage cells is sufficient to induce senescence and reduce bone mass. To do this, we will generate mice with oxidative stress- induced senescence in either the entire osteoblast lineage or only in mature osteoblasts and osteocytes. Administration of the senolytic PZ15227 will reveal what components of the phenotype are due to senescence. In Aim 2 we will determine the contribution of the p53/p21 pathway in osteoprogenitors to skeletal aging by aging mice with p53 or p21 loss-of-function. In Aim 3 we will investigate the differential contribution of senescent osteocytes to increased bone resorption in trabecular versus cortical bone with age by aging mice with GATA4 loss-of-function in osteocytes. We will also quantify osteocyte senescence in cortical versus trabecular bone and determine whether senescent osteocytes express higher levels of RANKL. Successful completion of these studies should establish for the first time whether senescence of osteoprogenitors and osteocytes contributes to the loss of bone mass with age, and help clarify different aging mechanisms in cortical versus trabecular bone.

项目概要/摘要衰老是导致女性和男性大多数骨折的原因。骨骼中的细胞变化老年小鼠的情况与在老年人类中观察到的情况相似。在小鼠中，小梁骨丢失与低骨重塑，而皮质变薄和孔隙度与高骨重塑有关。这些发现表明这两个区室骨质流失的分子机制不同。蜂窝网络随着年龄的增长，衰老会导致多种组织的功能衰退，DNA损伤是主要原因的衰老。 DNA 损伤通过激活 p53 和上调细胞周期抑制剂导致衰老第 21 页和/或第 16 页。 DNA 损伤还会导致转录因子 GATA4 的积累，从而促进衰老相关分泌表型（SASP）。衰老细胞的全身清除可延缓数个年龄相关疾病并增加老年小鼠的骨量。我们已经证明骨祖细胞的数量在小鼠骨髓中，随着年龄的增长，这些细胞的衰老标志物增加。皮质老年小鼠的骨细胞也表现出衰老标志物的增加，这与 RANKL 的生产。 DNA 损伤诱导骨器官培养物衰老足以增加 GATA4 和 RANKL 制作。此外，GATA4在体外的过度表达足以增加RANKL 以及 SASP 的其他组件。对年老小鼠施用衰老药物可减弱衰老标志物在骨祖细胞和骨细胞中。值得注意的是，骨细胞中缺乏 RANKL 的小鼠可以免受随着年龄的增长，皮质骨而不是小梁骨。我们假设骨祖细胞中 p53/p21 的激活导致它们衰老，从而减少成骨细胞数量和骨形成，衰老骨细胞在皮质而非小梁中的积累会增加 RANKL 和骨通过 GATA4 刺激进行吸收。在目标 1 中，我们将确定成骨细胞谱系细胞中的 DNA 是否受到损伤足以诱发衰老并减少骨量。为此，我们将培育具有氧化应激的小鼠- 在整个成骨细胞谱系中或仅在成熟的成骨细胞和骨细胞中诱导衰老。施用 senolytic PZ15227 将揭示表型的哪些成分是由于衰老引起的。在目标 2 中，我们将通过衰老确定骨祖细胞中 p53/p21 通路对骨骼衰老的贡献 p53 或 p21 功能丧失的小鼠。在目标 3 中，我们将研究衰老的不同贡献使用 GATA4 的衰老小鼠，骨细胞随着年龄的增长，骨小梁与皮质骨的骨吸收增加骨细胞功能丧失。我们还将量化皮质骨和小梁骨中骨细胞的衰老情况确定衰老骨细胞是否表达较高水平的 RANKL。顺利完成这些研究应首次确定骨祖细胞和骨细胞的衰老是否有助于随着年龄的增长骨质流失，并有助于阐明皮质骨和小梁骨的不同衰老机制。