Influence of Genetic Background on Bone Anabolic Response to Mechanical Loading

遗传背景对机械负荷下骨合成代谢反应的影响

基本信息

批准号：
10373527
负责人：
MATTHEW J SILVA
金额：
$ 21.44万
依托单位：
WASHINGTON UNIVERSITY
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：
2022-02-01 至 2024-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10373527
关键词：
3-Dimensional Address Aging Anabolism Animals Biology Cells Data Development Disease Environment Exhibits Exploratory/Developmental Grant Female Future Genes Genetic Genetic Transcription Genetic Variation Genotype Goals Heritability Human Inbred Strain Inbred Strains Mice Inbreeding Individual Knowledge Laboratories Lead Measures Mechanics Morphology Mouse Strains Mus Osteocytes Osteogenesis Osteoporosis Pharmaceutical Preparations Phenotype Physical activity Population Heterogeneity Protocols documentation Quantitative Trait Loci Research Research Personnel Resolution Resources Risk Sampling Stimulus Testing Tissues Variant Work X ray microscopy base bone bone mass causal variant confocal imaging cortical bone density fluid flow fracture risk gene discovery genotypic sex lifestyle factors male mechanical load microscopic imaging mouse genome mouse model novel strategies prevent response sex skeletal submicron trait transcriptome sequencing transcriptomics young adult

项目摘要

SUMMARY Osteoporosis is a heritable disease of low bone mass and increased fracture risk. Drugs are available to treat low bone mass, yet they carry risks and have limited indications. Thus, there remains a need for new approaches to prevent and treat osteoporosis. Mechanical loading can build and maintain bone mass in humans, and is a potent bone anabolic stimulus in animals. Studies of skeletal loading in mice provide a powerful platform to study bone anabolism at the gene, cell and tissue levels. Yet studies to date have been limited by a lack of genetic diversity – most murine bone loading studies have been done using inbred C57Bl/6 (B6) mice, and the few done with multiple strains used mice with limited genetic diversity. Thus, little is known about the contribution of genetic background to bone's anabolic response to mechanical loading. Our goal is to test the overall hypothesis that the response of bone to mechanical loading is heritable (i.e., depends on genetic background). We will test this using mice from eight genetically diverse inbred mouse strains, including five common laboratory strains and three wild-derived strains. These strains account for 89% of the variation in the mouse genome. In Aim 1, we will apply strain-matched tibial loading to young-adult mice of the eight inbred strains, and determine cortical bone formation responses. We will include female and male mice, to allow assessment of genotype and sex main effects, and sex-genotype interactions. We will then perform RNA-seq analysis on mouse strains identified as low and high responders in order to explore the transcriptomic differences that may drive the differential loading responses. Skeletal loading drives fluid flow in the osteocyte lacunocanalicular network (LCN), and it is widely believed that osteocytes transduce this fluid flow stimulus and regulate the anabolic response to loading. Changes to the LCN occur with osteoporosis and aging, and may alter the osteocyte micromechanical environment, and in turn the anabolic response to loading. In Aim 2, we propose to characterize LCN morphology in bones from the eight inbred strains, and test whether these traits vary between strains. We will use sub-micron resolution X-ray microscopy and confocal imaging to characterize the osteocyte LCN. We will then explore whether inter-strain variations in LCN morphology are associated with variations in anabolic response to loading between strains (from Aim 1). This proposal is appropriate as an R21 Exploratory/ Developmental grant. Aim 1 is developmental; it will establish whether bone's anabolic response to loading is heritable. If so, it will provide rationale for large-scale future studies using genetically diverse mice to discover genes that influence bone's response to loading. Aim 2 will assess the heritability of osteocyte LCN morphology, which may likewise motivate future studies to identify causal genes. It will also explore a fundamental question in bone mechanobiology – whether bone's response to loading depends on osteocyte LCN morphology.

概括骨质疏松症是一种骨量低且骨折风险增加的遗传性疾病。治疗低骨量，但它们存在风险并且适应症有限，因此仍然需要新的治疗方法。预防和治疗骨质疏松症的方法机械负荷可以建立和维持骨量。对小鼠骨骼负荷的研究提供了一种对人类有效的骨合成代谢刺激。迄今为止的研究已经成为在基因、细胞和组织水平上研究骨合成代谢的强大平台。受缺乏遗传多样性的限制——大多数小鼠骨负荷研究都是使用近交系进行的 C57Bl/6 (B6) 小鼠，以及少数使用多种品系的小鼠，其遗传多样性有限。关于遗传背景对骨骼对机械的合成代谢反应的贡献知之甚少。我们的目标是检验骨骼对机械载荷的响应的总体假设。可遗传（即取决于遗传背景），我们将使用来自八种遗传多样性的小鼠进行测试。近交系小鼠品系，包括五种常见的实验室品系和三种野生品系。占小鼠基因组变异的 89% 在目标 1 中，我们将应用应变匹配的胫骨负载。我们将研究八个近交系的年轻成年小鼠，并确定皮质骨形成反应。包括雌性和雄性小鼠，以评估基因型和性别主要影响以及性别基因型然后，我们将对被鉴定为低反应和高反应的小鼠品系进行 RNA 测序分析。为了探索可能驱动骨骼负荷反应差异的转录组差异。负载驱动骨细胞腔隙小管网络 (LCN) 中的流体流动，人们普遍认为骨细胞传导这种流体流动刺激并调节对负荷变化的合成代谢反应。 LCN 随骨质疏松和衰老而发生，并可能改变骨细胞的微机械环境，并且在在目标 2 中，我们建议表征骨骼中的 LCN 形态。八个近交菌株，并测试这些性状在菌株之间是否存在差异，我们将使用亚微米。然后我们将通过分辨率 X 射线显微镜和共焦成像来表征骨细胞 LCN。 LCN形态的品系间差异是否与合成代谢反应的变化相关菌株之间的负载（来自目标 1）。该提案适合作为 R21 探索/发展。目标 1 是发育性的；它将确定骨骼对负荷的合成代谢反应是否可遗传。因此，它将为未来使用基因多样化的小鼠来发现基因的大规模研究提供依据影响骨骼对负荷的反应目标 2 将评估骨细胞 LCN 形态的遗传力，这可能同样会激发未来的研究来确定因果基因，它也将探索一个基本的原因。骨力学生物学问题 – 骨骼对负荷的反应是否取决于骨细胞 LCN 形态学。