The role of Piezo1 in bone homeostasis and mechanotransduction

Piezo1 在骨稳态和力传导中的作用

• 批准号: 10642770
• 负责人: Jinhu Xiong
• 金额: $ 33.44万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-17 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10642770
• 关键词: Adult; Aging; Agonist; Alleles; Area; Bone Formation Stimulation; Bone Growth; Bone Matrix; Bone Regeneration; Bone Resorption; Bone remodeling; Calcium; Calcium Channel; Calcium Channel Inhibition; Calcium Signaling; Cell Surface Proteins; Cell model; Cells; Chemicals; Cilia; Complement; Development; Elderly; Enterobacteria phage P1 Cre recombinase; Exhibits; Focal Adhesions; Generations; Genes; Hindlimb Suspension; Homeostasis; Immobilization; In Vitro; Individual; Integrins; Ion Channel; Knockout Mice; Knowledge; Ligands; Liquid substance; Mechanical Stimulation; Mechanics; Mediating; Modeling; Molecular; Mus; Osteoblasts; Osteoclasts; Osteocytes; Osteogenesis; Phenotype; Piezo 1 ion channel; Play; Rattus; Regenerative response; Role; Signal Pathway; Skeleton; Stimulus; Structure; Tail; Tail Suspension; Testing; Transgenes; Transgenic Mice; WNT Signaling Pathway; Wild Type Mouse; Work; bone; bone loss; bone mass; bone strength; conditional knockout; cortical bone; dentin matrix protein 1; fluid flow; fracture risk; genetic approach; human old age (65+); in vivo; inhibitor; mechanical force; mechanical load; mechanical signal; mechanical stimulus; mechanotransduction; mouse genetics; osteoblast differentiation; overexpression; pharmacologic; postnatal; prevent; response; shear stress; skeletal; substantia spongiosa; therapy development; tibia; ulna

PROJECT SUMMARY/ABSTRACT Mechanical stimuli promote bone growth and are critical for skeletal homeostasis during adulthood. Loss of mechanical signals decreases bone mass and increases fracture risk. Osteocytes, which are cells buried in the bone matrix and derived from osteoblasts, are able to sense changes in mechanical load and orchestrate bone remodeling. Several lines of evidence suggest that calcium channels are involved in the sensing of mechanical load by osteocytes. For example, calcium influx is one of the earliest responses of osteocytes to mechanical stimuli in vitro and in vivo. Consistent with a functional role for calcium signaling in the response to mechanical forces, the response of osteocytes to mechanical stimuli can be inhibited by blocking calcium channels using chemical blockers. Moreover, load-induced bone formation in the rat ulna is significantly blunted by calcium channel inhibitors. However, the identity of the calcium channels activated by mechanical forces and their functional role as mechanosensors in bone remain unclear. We have found that Piezo1 calcium channel is highly expressed in osteocytes, and that its expression and activity are increased by mechanical stimulation in osteocytes. In addition, deletion of Piezo1 in osteoblasts and osteocytes decreases both bone mass and bone strength in mice, consistent with loss of skeletal responsiveness to mechanical stimulation. Moreover, the skeletal response to anabolic loading is blunted in mice lacking Piezo1 in osteoblasts and osteocytes. Wnt1, a ligand for Wnt signaling that is known to be upregulated by mechanical signals and stimulate bone formation, is downregulated in Piezo1 conditional knockout mice. Importantly, activation of Piezo1 by its chemical agonist, Yoda1, mimics the effects of fluid flow on osteocytes and increases bone mass in mice. Based on this evidence, we hypothesize that osteocytes sense changes in mechanical signals through Piezo1 and thereby promote bone formation in part by activating signaling pathways that increase the expression of Wnt1. To test this hypothesis, we will determine whether Piezo1 expression by osteocytes is required for mechanical sensing in the murine skeleton. We will generate mice in which Piezo1 is deleted from osteocytes, but not osteoblasts, and compare their skeletal phenotype to that observed in mice lacking Piezo1 in osteoblasts and osteocytes. We also will delete Piezo1 postnatally in adult mice and investigate their response to mechanical loads by tibia compression (Aim 1). In addition, to understand how Piezo1 promotes bone formation, we will determine the role of Wnt1 in Piezo1-mediated bone formation in vivo using a mouse genetic approach (Aim 2). In Aim 3, we will determine whether Piezo1 is responsible for the skeletal response to unloading using a tail-suspension model. Lastly, we will determine whether pharmacological activation of Piezo1 prevents bone loss associated with unloading or increases bone mass in old mice. Successful completion of this work should establish a new model for understanding the skeletal response to anabolic mechanical loading and may suggest new strategies to develop anabolic therapies for bone loss related to disuse or aging.

项目摘要/摘要 机械刺激会促进骨骼的生长，对于成年期的骨骼稳态至关重要。损失 机械信号会降低骨骼质量并增加断裂风险。骨细胞，是埋在 骨基质并源自成骨细胞，能够感知机械负荷的变化和编排骨骼 重塑。几条证据表明，钙通道参与了机械感应 通过骨细胞负载。例如，钙涌入是骨细胞对机械的最早反应之一 体外和体内刺激。与钙信号的功能作用一致 力量，骨细胞对机械刺激的反应可以通过使用使用钙通道来抑制 化学阻滞剂。此外，大鼠尺骨中负荷诱导的骨骼形成显着被钙显着钝化 通道抑制剂。但是，由机械力及其激活的钙通道的身份 作为骨骼中的机械传感器的功能作用尚不清楚。我们发现Piezo1钙通道是 在骨细胞中高度表达，其表达和活性通过机械刺激而增加 骨细胞。此外，在成骨细胞和骨细胞中的压电1删除会减少骨骼和骨骼 小鼠的强度，与机械刺激的骨骼反应能力的丧失一致。而且， 在成骨细胞和骨细胞中缺少压电的小鼠中，对合成代谢负荷的骨骼反应钝化。 Wnt1，a Wnt信号的配体已知被机械信号上调并刺激骨形成，IS 在压电1中下调有条件的敲除小鼠。重要的是，其化学激动剂对压电1的激活， Yoda1，模仿流体流对骨细胞的影响，并增加小鼠的骨骼量。基于此 有证据，我们假设骨细胞感知通过压电的机械信号的变化 通过激活提高WNT1表达的信号通路的部分促进骨形成。测试 这个假设，我们将确定机械传感是否需要骨细胞的压电表表达 在鼠骨架中。我们将生成从骨细胞中删除的piezo1的鼠标，而不是成骨细胞， 并将其骨骼表型与在成骨细胞和骨细胞缺乏压电的小鼠中观察到的骨骼表型。 我们还将在成年小鼠的产后删除压电1，并研究胫骨对机械负荷的反应 压缩（目标1）。此外，为了了解Piezo1如何促进骨形成，我们将确定 Wnt1使用小鼠遗传方法在压电1介导的骨形成中的作用（AIM 2）。在AIM 3中，我们 将确定Piezo1是否负责使用尾部悬浮的骨骼响应 模型。最后，我们将确定Pilezo1的药理学激活是否可以防止与骨质流失相关 随着卸载或增加旧小鼠的骨骼质量。成功完成这项工作应该建立一个新的 理解对合成代谢机械加载的骨骼响应的模型，并可能提出新策略 开发用于废弃或衰老有关的骨流失的代谢疗法。