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

基本信息

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
项目类别：
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

项目摘要

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.

项目概要骨质疏松症和其他骨骼脆弱疾病影响着全世界 2 亿多人每年可预防约 900 万处骨折，并/或恢复患者丢失的骨量。对于限制骨骼脆弱疾病对个人和经济的影响至关重要。刺激新骨形成的是蛋白质硬化蛋白，它是 Wnt/β-连环蛋白信号传导的拮抗剂级联，由骨嵌入的骨细胞产生，包括许多骨合成代谢信号。机械负荷，减少硬化蛋白的表达，导致成骨细胞生成“去抑制” 然而，骨细胞如何感知机械的关键机制细节。负载，将这些负载信号转导至生物效应器，这些生物效应器的身份以及如何硬化素生物利用度的调节尚不清楚。我们的初步数据发现了一些新的发现。具体来说，我们发现微管是骨细胞如何感知和响应机械信号的介质。依赖的细胞骨架刚度调节机械激活的 Ca2+ 流入此外，我们暗示 TRPV4。作为主要的机械依赖性 Ca2+ 流入途径，驱动 Ca2+ 依赖性激活钙/钙调蛋白依赖性激酶 II (CamKII) 可降低骨细胞中硬化素的生物利用度。目前的资助，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与骨细胞机械传感，定义骨细胞的贡献和机制 TRPV4 通道响应机械应力而打开，并阐明 FFSS- 的机制依赖的 CamKII 激活调节硬化蛋白降解和 Sost 基因转录。充分解释硬化素的生物调节，将机械地连接几个知识空白骨细胞如何感知和响应机械负荷，并将揭示改善或保持的新目标衰老和疾病中的骨量。