Rspondin-Lgr Axis in Bone Regeneration

骨再生中的 Rspondin-Lgr 轴

• 批准号: 10469469
• 负责人: Kurt David Hankenson
• 金额: $ 37.94万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-10 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10469469
• 关键词: Address; Adult; Attenuated; BMP2 gene; Binding; Bone Injury; Bone Regeneration; Bone callus; Calvaria; Cell Lineage; Cells; Chondrocytes; Clinical; Data; Defect; Development; Embryo; Family; Family member; Fracture; GPR4 gene; Genes; Goals; Hand; Histology; In Vitro; Incidence; Individual; Injury; Knockout Mice; Lead; Leucine-Rich Repeat; Ligands; Limb Development; Limb structure; LoxP-flanked allele; Mechanics; Mesenchymal; Mesenchymal Stem Cells; Mesenchyme; Minerals; Modeling; Molecular; Molecular Analysis; Mus; Osteoblasts; Osteogenesis; Pathway interactions; Periosteal Cell; Periosteum; Play; Positioning Attribute; Process; Property; Proteins; Public Health; Publishing; Receptor Signaling; Recombinants; Regulation; Reporter; Research; Role; Signal Transduction; Site; Skeletal Development; Testing; Therapeutic Uses; Time; WNT Signaling Pathway; base; bone; bone fracture repair; bone healing; bone repair; craniofacial; healing; in vivo; injured; long bone; mRNA Expression; microCT; mouse model; novel; novel strategies; novel therapeutics; osteoblast differentiation; osteochondral tissue; osteogenic; osteoprogenitor cell; prevent; progenitor; protein function; receptor; regenerative therapy; response; response to injury; skeletal; stem; stem cells; tissue regeneration

There is an urgent clinical need to develop new therapeutics to promote bone regeneration. A critical aspect of the bone healing process begins with the expansion of periosteal progenitors that occurs immediately after injury and then the differentiation of these progenitors to bone forming osteoblasts and chondrocytes, yet mechanisms that control skeletal progenitor/stem cell activation, expansion, and differentiation in response to injury are poorly described. Our project will study the role of the R-spondin (ligand) – Lgr (receptor) signaling axis in regulating these 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 fracture healing has never been examined due to lack of appropriate models. Our primary goal is to define the requirement of Rspo2/3 and Lgr6 in mesenchymal progenitors in response to bone injury. We have defined three 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 mesenchymal progenitors at the time of fracture. Bone healing will be assessed using microCT, histology, molecular analysis, and mechanical testing. Alterations in canonical Wnt signaling and osteogenic potential of Rspo2/3 deficient progenitors will be assessed. In Aim 2, Lgr6 knockout mice will be investigated for their bone healing properties using parameters similar to Aim 1. In Aim 3, Rspo2 will be delivered to bone injury sites and the impact on BMP and Wnt signaling, progenitor activation and differentiation, and bone healing assessed. Completion of this project will identify the requirement of Rspo2/3-Lgr6 interaction in fracture healing and will provide new therapeutic directions for enhancing bone healing.

临床迫切需要开发新的疗法来促进骨再生。一个 骨愈合过程的关键部分始于骨膜祖细胞的扩张 损伤后立即发生，然后这些祖细胞分化为骨 形成成骨细胞和软骨细胞，以及控制骨骼祖细胞/干细胞的机制 对损伤反应的激活、扩张和分化的描述很少。我们的项目 将研究 R-spondin（配体）-Lgr（受体）信号轴在调节这些信号中的作用 祖细胞和骨再生。 R-spondins（屋顶板特异性 spondins）是一个四族家族 分泌的基质细胞蛋白 (Rspo1-4)，与富含亮氨酸重复序列的 G 蛋白结合 偶联受体 4/5/6 (Lgrs)。 Rspo-Lgr 相互作用通过以下方式增强经典 Wnt 通路 阻止 Wnt 卷曲受体的更新，从而确定典型的 Wnt 信号水平。虽然已知经典 Wnt 信号传导在骨骼中发挥重要作用 再生方面，很少有研究探索 Wnt 信号传导的正调节剂。在 特别是，骨折愈合中 Rspo-Lgr 的要求从未得到满足 由于缺乏合适的模型而受到审查。我们的主要目标是定义以下要求 间充质祖细胞中的 Rspo2/3 和 Lgr6 对骨损伤的反应。我们已经定义了 实现这一目标的三个具体目标。在 Aim1 中，我们将使用单一和复合 Rspo2 和 Rspo3 floxed 小鼠与 alphaSMACreERT2 小鼠杂交以破坏 Rspo2/3 基因 骨折时的间充质祖细胞。将使用 microCT 评估骨愈合情况， 组织学、分子分析和机械测试。典型 Wnt 信号传导的改变 将评估 Rspo2/3 缺陷祖细胞的成骨潜力。在目标 2 中，Lgr6 将使用类似于以下参数的参数来研究基因敲除小鼠的骨愈合特性： 目标1.目标3中，Rspo2将被递送到骨损伤部位以及对BMP和Wnt的影响 信号传导、祖细胞激活和分化以及骨愈合进行评估。完成 该项目将确定骨折愈合中 Rspo2/3-Lgr6 相互作用的要求，并将 为增强骨愈合提供新的治疗方向。