Mechanisms of osteocyte mechano-signaling and sclerostin regulation

骨细胞机械信号传导和硬化素调节机制

• 批准号: 9922216
• 负责人: Joseph P. Stains
• 金额: $ 33.99万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-03-21 至 2023-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9922216
• 关键词: Acute; Affect; Aging; Biological; Biological Availability; Biomechanics; Bone remodeling; Calcium; Calcium Channel; Calmodulin; Cations; Cell physiology; Cells; Cilia; Consensus; Cues; Cultured Cells; Cytoskeleton; Data; Disease; Down-Regulation; Drug Targeting; Elements; Enzymes; Genes; Genetic; Genetic Transcription; Grant; Health; Human; In Vitro; Integrins; Knockout Mice; Knowledge; Link; Liquid substance; Mechanical Stress; Mechanics; Mediator of activation protein; Messenger RNA; Microtubule-Associated Proteins; Microtubules; Modeling; Molecular; Mutation; NADPH Oxidase; Osteocytes; Osteogenesis; Osteoporosis; Outcome; Outcome Measure; Pathway interactions; Patients; Pharmacology; Phenotype; Phosphotransferases; Play; Post-Translational Protein Processing; Proteins; Reactive Nitrogen Species; Reactive Oxygen Species; Regulation; Repression; Role; Second Messenger Systems; Signal Pathway; Signal Transduction; Skeleton; Source; Striated Muscles; Structure; Testing; Tissues; Translating; Tubulin; Vanilloid; Work; alpha Tubulin; base; beta catenin; bone; bone loss; bone mass; bone preservation; bone quality; conditional knockout; crosslink; defined contribution; density; economic impact; genetic approach; improved; in vivo; in vivo Model; insight; loss of function; mechanical load; mechanotransduction; mutant; new therapeutic target; novel; osteogenic; prevent; primary outcome; receptor; response; sensor; shear stress; skeletal; skeletal disorder; tool

PROJECT SUMMARY Osteoporosis and other diseases of skeletal fragility affect more than 200 million people worldwide and contributes to ~9 million factures annually. Preventing bone loss and/or restoring lost bone mass in patients is of vital importance to limiting the personal and economic impact of diseases of skeletal fragility. A key target in the stimulation of new bone formation is the protein sclerostin, an antagonist of the Wnt/beta-catenin signaling cascade, which is produced by bone embedded osteocytes. Numerous osteoanabolic cues, including mechanical load, reduce expression of the sclerostin leading to “de-repression” of osteoblastogenesis and stimulation of de novo bone formation. However, key mechanistic details of how osteocytes sense mechanical load, transduce these load signals to biologic effectors, the identity of these biological effectors and how sclerostin bioavailability is regulated are unclear. Our preliminary data have uncovered a number of novel mediators of how osteocytes sense and respond to mechanical cues. Specifically, we show that microtubule- dependent cytoskeletal stiffness regulates mechano-activated Ca2+ influx. Furthermore, we implicate TRPV4 as a major mechano-dependent Ca2+ influx pathway that drives Ca2+ dependent activation of calcium/calmodulin-dependent kinase II (CamKII) to reduce sclerostin bioavailability in the osteocyte. In the present grant, we will use in vitro, ex vivo and in vivo models to determine the contribution of MT density and cytoskeletal crosslinking to osteocyte mechanosensing, define the contribution and mechanisms of osteocyte TRPV4 channel opening in response to mechanical stress and elucidate the mechanisms by which FFSS- dependent CamKII activation regulates sclerostin degradation and Sost gene transcription. This work will more fully explain the biological regulation of sclerostin, will mechanistically link several gaps in the knowledge of how osteocytes sense and respond to mechanical load, and will reveal novel targets to improve or preserve bone mass in aging and disease.

项目摘要 骨质疏松症和骨骼脆弱性的其他疾病影响着全球超过2亿人， 每年造成约900万个事件。预防患者的骨质流失和/或恢复患者的骨骼肿块是 对于限制骨骼脆弱性疾病的个人和经济影响至关重要。一个关键目标 新骨形成的刺激是蛋白质硬化素，这是Wnt/beta-catenin信号传导的拮抗剂 级联，由骨骼嵌入骨细胞产生。许多骨代谢提示，包括 机械负荷，减少硬化素的表达，从而导致成骨细胞生成的“抑制”和 刺激从头形成。但是，骨细胞如何感知机械的关键机械细节 负载，将这些负载信号转化为生物学效应，这些生物学效应的身份以及如何 尚不清楚硬化性生物利用度。我们的初步数据已经发现了许多新颖的 骨细胞如何感知并响应机械提示的介体。具体而言，我们表明微管 依赖性细胞骨架刚度调节机械激活的Ca2+影响。此外，我们暗示TRPV4 作为主要的机械依赖性Ca2+影响驱动Ca2+依赖性激活的途径 钙/钙调蛋白依赖性激酶II（CAMKII），以减少骨细胞中的硬化素生物利用度。在 目前的赠款，我们将使用体外，离体和体内模型来确定MT密度和 细胞骨架交联至骨细胞机理，定义骨细胞的贡献和机制 TRPV4通道响应机械应力，并阐明了FFSS-的机制 依赖性的CAMKII激活调节硬化蛋白降解和SOST基因转录。这项工作将更多 充分解释硬化蛋白的生物学调节，将机械地将几个差距联系起来 骨细胞如何感知并响应机械负载，并将揭示新的目标以改进或保存 衰老和疾病中的骨骼质量。