Rspondin-Lgr Axis in Bone Regeneration

骨再生中的 Rspondin-Lgr 轴

基本信息

批准号：
10261766
负责人：
Kurt David Hankenson
金额：
$ 40.01万
依托单位：
UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-09-18 至 2022-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10261766
关键词：
Address Adult Attenuated Binding Bone Injury Bone Regeneration Bone callus Calvaria Cell Compartmentation Cell Lineage Cells Chondrocytes Clinical Data Development Embryo Family Family member Femoral Fractures Fracture Fracture Healing Funding GPR4 gene Genes Goals Grant Hand Histology In Vitro Incidence Injury Knockout Mice Lead Leucine-Rich Repeat Ligands Limb Development Limb structure LoxP-flanked allele Marrow Mechanics Mesenchymal Mesenchymal Stem Cells Mesenchyme Minerals Modeling Molecular Mus Natural regeneration Osteoblasts Osteogenesis Pathway interactions Periosteal Cell Periosteum Play Positioning Attribute Process Property Proteins Public Health Publishing Receptor Signaling Regulation Research Role Signal Transduction Skeletal bone Source Testing Therapeutic Uses Time WNT Signaling Pathway base bone bone healing cranium experimental study healing in vivo injured insight long bone mRNA Expression mouse model novel novel strategies osteoblast differentiation osteochondral tissue osteogenic osteoprogenitor cell parent grant prevent progenitor receptor regenerative therapy repaired response response to injury skeletal stem cell proliferation stem cells tissue regeneration

项目摘要

Our funded grant, R01DE030716, ”Rspondin-Lgr Axis in Bone Regeneration”, is focused on examining the role of Rspo2-Lgr6 signaling in calvarial regeneration. While there are some similarities in healing processes that exist between long bones and bones of the skull, there are also important differences. As an example, the calvaria heals exclusively through an intramembranous process while long bones heal through both intramembranous and endochondral bone formation. An additional important difference that exists between calvarial and long bone healing is the source and type of progenitor cell that contributes to bone healing. In long bones, a critical aspect of the bone healing process begins with the expansion of mesenchymal progenitors from the marrow and periosteum, which occurs immediately after injury. These cells then become bone forming osteoblasts and chondrocytes. However, mechanisms that control long-bone skeletal progenitor/stem cell activation, expansion, and differentiation in response to injury are poorly described. This supplement will study the role of the R-spondin (ligand) – Lgr (receptor) signaling axis in regulating long bone progenitors and bone regeneration. R-spondins (roof plate specific spondin) are a family of four secreted matricellular proteins (Rspo1-4) that bind to Leucine-rich repeat-containing G-protein coupled receptors 4/5/6 (Lgrs). Rspo-Lgr interaction potentiate canonical Wnt pathway by preventing the turnover of Wnt Frizzled receptors, and hence determines canonical Wnt signaling levels. While canonical Wnt signaling is known to play an important role in bone regeneration, very little research has explored positive modulators of Wnt signaling. In particular, the requirement of Rspo-Lgr in the context of long-bone fracture healing has never been examined, due to the lack of appropriate models. Our primary goal is to define the requirement of Rspo2/3 and Lgr6 in mesenchymal progenitors in response to femoral fracture. We have defined two specific aims to address this goal. In Aim1, we will use single and compound Rspo2 and Rspo3 floxed mice crossed with an alphaSMACreERT2 mouse to disrupt the Rspo2/3 genes in long-bone mesenchymal progenitors at the time of fracture. We will assess in vivo proliferation, Wnt signaling, and osteogenesis of progenitors, and analyze healing by using µCT, histology, and mechanical testing. In Aim 2, Lgr6 knockout mice will be investigated for their bone healing properties using parameters similarly to Aim 1. Completion of this project will identify the requirement of Rspo2/3-Lgr6 interaction in long-bone fracture healing and will provide new mechanistic insights into the action of cWnt signaling in bone healing that can be directly compared to similar experiments conducted with calvarial healing in the parent grant.

我们资助的赠款 R01DE030716“Rspondin-Lgr 轴在骨再生中”的重点是研究该作用 Rspo2-Lgr6 信号在颅骨再生中的作用虽然在愈合过程中存在一些相似之处。长骨和头骨之间存在着重要的区别，例如，颅骨仅通过膜内过程愈合，而长骨则通过这两种过程愈合膜内骨形成和软骨内骨形成之间存在另一个重要区别。颅骨和长骨愈合是有助于骨愈合的祖细胞的来源和类型。长骨，骨愈合过程的一个关键方面始于间充质的扩张损伤后立即产生来自骨髓和骨膜的祖细胞。然而，成骨细胞和软骨细胞控制长骨骨骼的机制。祖细胞/干细胞响应损伤的激活、扩增和分化的描述很少。补充剂将研究 R-spondin（配体）-Lgr（受体）信号轴在调节长骨中的作用祖细胞和骨再生 R-spondins（顶板特异性 spondin）是一个由四个分泌细胞组成的家族。与富含亮氨酸重复序列的 G 蛋白偶联受体 4/5/6 结合的基质细胞蛋白 (Rspo1-4) (Lgrs)。Rspo-Lgr 相互作用通过阻止 Wnt Frizzled 的更新来增强经典 Wnt 通路。受体，从而决定经典 Wnt 信号传导水平，而已知经典 Wnt 信号传导水平在骨再生中发挥重要作用，但很少有研究探索 Wnt 的正调节剂特别是，在长骨骨折愈合过程中对 Rspo-Lgr 的需求从未如此。由于缺乏适当的模型，我们的主要目标是定义需求。间充质祖细胞中的 Rspo2/3 和 Lgr6 对股骨骨折的反应我们已经定义了两种特定的。旨在实现这一目标，在 Aim1 中，我们将使用单一和复合 Rspo2 和 Rspo3 floxed 小鼠杂交。使用 alphaSMACreERT2 小鼠破坏长骨间充质祖细胞中的 Rspo2/3 基因我们将评估祖细胞的体内增殖、Wnt 信号传导和成骨作用，以及在目标 2 中，将使用 µCT、组织学和机械测试来分析愈合情况。使用与目标 1 类似的参数研究其骨愈合特性。该项目的完成将确定 Rspo2/3-Lgr6 相互作用在长骨骨折愈合中的要求，并将提供新的对 cWnt 信号在骨愈合中作用的机制见解，可以直接与类似的在父母资助下进行的颅骨愈合实验。