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: 10418767
• 负责人: Jinhu Xiong
• 金额: $ 33.11万
• 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/10418767
• 关键词: Adult; Aging; Agonist; Alleles; Area; Bone Growth; Bone Matrix; Bone Regeneration; Bone remodeling; Calcium; Calcium Channel; 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; Pharmacology; 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; base; 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; 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.

项目概要/摘要 机械刺激促进骨骼生长，对于成年期骨骼稳态至关重要。损失 机械信号会降低骨量并增加骨折风险。骨细胞，是埋藏在骨中的细胞 骨基质源自成骨细胞，能够感知机械负荷的变化并协调骨骼 重塑。多项证据表明钙通道参与机械感应 骨细胞负载。例如，钙流入是骨细胞对机械力的最早反应之一。 体外和体内的刺激。与钙信号在机械响应中的功能作用一致 力，可以通过使用阻断钙通道来抑制骨细胞对机械刺激的反应 化学阻滞剂。此外，钙显着削弱了大鼠尺骨中负荷诱导的骨形成 通道抑制剂。然而，机械力激活的钙通道的特性及其 作为机械传感器在骨骼中的功能作用仍不清楚。我们发现Piezo1钙通道是 在骨细胞中高表达，并且其表达和活性通过机械刺激而增加 骨细胞。此外，成骨细胞和骨细胞中 Piezo1 的缺失会降低骨量和骨密度。 小鼠的力量，与骨骼对机械刺激的反应性丧失一致。此外， 在成骨细胞和骨细胞中缺乏 Piezo1 的小鼠中，骨骼对合成代谢负荷的反应减弱。 Wnt1，一个 Wnt 信号传导的配体已知可通过机械信号上调并刺激骨形成，是 Piezo1 条件敲除小鼠中下调。重要的是，Piezo1 通过其化学激动剂激活， Yoda1 模拟液体流动对骨细胞的影响并增加小鼠的骨量。基于此 根据证据，我们假设骨细胞通过 Piezo1 感知机械信号的变化，从而 部分通过激活增加 Wnt1 表达的信号通路来促进骨形成。测试 根据这个假设，我们将确定机械传感是否需要骨细胞表达 Piezo1 在小鼠骨骼中。我们将培育出骨细胞中删除 Piezo1 的小鼠，但成骨细胞中不删除 Piezo1， 并将它们的骨骼表型与在成骨细胞和骨细胞中缺乏 Piezo1 的小鼠中观察到的骨骼表型进行比较。 我们还将在成年小鼠出生后删除 Piezo1，并研究它们对胫骨机械负载的反应 压缩（目标 1）。此外，为了了解 Piezo1 如何促进骨形成，我们将确定 使用小鼠遗传方法研究 Wnt1 在 Piezo1 介导的体内骨形成中的作用（目标 2）。在目标 3 中，我们 将确定 Piezo1 是否负责使用尾部悬架卸载时的骨骼响应 模型。最后，我们将确定 Piezo1 的药理激活是否可以预防相关的骨质流失 减轻或增加老年小鼠的骨量。这项工作的成功完成应该建立一个新的 用于理解骨骼对合成代谢机械负荷的反应的模型，并可能提出新的策略 开发合成代谢疗法来治疗与废用或衰老相关的骨质流失。