Rspondin-Lgr Axis in Bone Regeneration

骨再生中的 Rspondin-Lgr 轴

• 批准号: 10260493
• 负责人: Kurt David Hankenson
• 金额: $ 76.68万
• 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/10260493
• 关键词: Address; Attenuated; BMP2 gene; Binding; Bone Injury; Bone Regeneration; Bone callus; Calvaria; Cell Lineage; Cells; Chondrocytes; Clinical; Data; Defect; Development; Embryo; Family; Family member; Fracture; Fracture Healing; 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 healing; 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; repaired; 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.

临床上迫切需要开发新的治疗方法来促进骨再生。一 骨愈合过程的关键方面始于骨膜祖细胞的扩张 然后这些祖细胞分化成骨 形成成骨细胞和软骨细胞，但控制骨骼祖细胞/干细胞的机制 对损伤后的激活、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）信号传导轴在调节这些过程中的作用。 祖细胞和骨再生。R-spondins（顶板特异性spondin）是一个四个家族 分泌的基质细胞蛋白（Rspo 1 -4），与富含亮氨酸的重复序列的G蛋白结合 偶联受体4/5/6（LGR）。Rspo-Lgr相互作用通过增强经典Wnt途径 阻止Wnt卷曲受体的周转，因此决定了典型的Wnt 信号水平。虽然已知典型的Wnt信号传导在骨骼中起重要作用， 再生，很少有研究探索Wnt信号传导的正调节剂。在 特别地，在骨折愈合的背景下对Rspo-Lgr的需求从未被 由于缺乏合适的模型。我们的主要目标是定义 间充质祖细胞中的Rspo 2/3和Lgr 6对骨损伤的反应我们已经定义 三个具体目标来实现这一目标。在目标1中，我们将使用单个和复合Rspo 2， Rspo 3 floxed小鼠与alphaSMACreERT 2小鼠杂交，以破坏细胞中的Rspo 2/3基因。 间充质祖细胞在骨折的时候。将使用microCT评估骨愈合， 组织学、分子分析和机械测试。经典Wnt信号传导的改变 并评估Rspo 2/3缺陷祖细胞的成骨潜力。在目标2中，Lgr 6 将使用类似于以下的参数研究敲除小鼠的骨愈合特性： 目标1.在目标3中，Rspo 2将被递送到骨损伤部位，并对BMP和Wnt的影响进行了研究。 信号传导、祖细胞活化和分化以及骨愈合。完成 本项目将确定骨折愈合中Rspo 2/3-Lgr 6相互作用的要求，并将 为促进骨愈合提供了新的治疗方向。