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

• 批准号: 10553706
• 负责人: MATTHEW J SILVA
• 金额: $ 17.98万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10553706
• 关键词: 3-Dimensional; Address; Aging; Anabolism; Animals; Biology; C57BL/6 Mouse; 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; Maps; 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; Risk Reduction; Sampling; Stimulus; Testing; Tissues; Variant; Work; Writing; X ray microscopy; 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

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 骨质疏松症是一种可遗传的疾病，患有低骨质和骨折风险增加。毒品可用于 治疗低骨头，但它们具有风险，并且指示有限。那仍然需要新的 预防和治疗骨质疏松症的方法。机械载荷可以在 人类，是动物中潜在的骨合成代谢刺激。小鼠骨骼负荷的研究提供了 在基因，细胞和组织水平上研究骨合成代谢的强大平台。迄今为止的研究已经 由于缺乏遗传多样性的限制 - 大多数鼠骨负荷研究都是使用近交的 C57BL/6（B6）小鼠，少数使用多种菌株使用的小鼠遗传多样性有限。那， 关于遗传背景对骨骼的合成代谢反应的贡献知之甚少 加载中。我们的目标是检验总体假设，即骨头对机械负荷的反应是 可遗传（即取决于遗传背景）。我们将使用来自八个普通潜水的小鼠进行测试 近交小鼠菌株，包括五种普通实验室菌株和三个野生菌株。这些菌株 占小鼠基因组变异的89％。在AIM 1中，我们将应用应变匹配的胫骨负荷 到八种近交菌株的年轻成年小鼠，并确定皮质骨形成反应。我们将 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生成型 互动。然后，我们将对识别为低反应者和高响应者的小鼠菌株进行RNA-seq分析 为了探索可能驱动差分加载响应的转录组差异。骨骼 在骨细胞lacunocanalicular网络（LCN）中加载流体流动，并广泛认为 骨细胞会转导这种流体流动刺激并调节合成代谢对负载的反应。更改 LCN发生在骨质疏松和衰老时，可能会改变骨细胞的微力环境，并在 将代谢响应转换为加载。在AIM 2中，我们建议表征骨骼中的LCN形态 八个近交菌株，并测试这些特征在菌株之间是否有所不同。我们将使用子微调 分辨率X射线显微镜和共聚焦成像以表征骨细胞LCN。然后我们将探索 LCN形态学的交通间变化是否与合成代谢反应的变化有关 菌株之间的负载（来自AIM 1）。该提案作为R21探索/发展是合适的 授予。目标1是发展的；它将确定骨骼对加载的合成代谢反应是否可遗传。如果 因此，它将为大规模的未来研究提供基本原理，使用一般多样的小鼠发现基因 这会影响骨头对负载的反应。 AIM 2将评估骨细胞LCN形态的遗传力， 这可能同样激发了未来的研究以鉴定毒素基因。它也将探索一个基本 骨骼机械生物学中的问题 - 骨头对负载的反应是否取决于骨细胞LCN 形态学。