Rspondin-Lgr Axis in Bone Regeneration

临床上迫切需要开发新的治疗方法来促进骨再生。一个 骨愈合过程的关键方面始于骨膜祖细胞的扩张。 这在损伤后立即发生，然后这些祖细胞分化为骨 形成成骨细胞和软骨细胞，但控制骨骼祖细胞/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 我将研究R-响应素(配体)-LGR(受体)信号轴在调节这些方面的作用 祖细胞和骨骼再生。R-Spinins(屋顶板特异性Spinins)是一个四口之家。 与富含亮氨酸重复序列的G蛋白结合的分泌型基质细胞蛋白(Rsp1-4) 偶联受体4/5/6(LGRS)。RSPO-LGR相互作用通过以下途径增强Wnt途径 阻止Wnt Frizzled型受体的翻转，从而决定典型的Wnt 信令级别。虽然已知经典的Wnt信号在骨骼中扮演着重要的角色 在再生方面，很少有研究探索Wnt信号的正向调节器。在……里面 特别是，在骨折愈合的背景下，RSPO-LGR的要求从未被 由于缺乏适当的模型而进行了审查。我们的主要目标是定义以下要求 Rsp2/3和Lgr6在间充质祖细胞对骨损伤反应中的作用。我们已经定义了 解决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系小鼠与一只AlphaSMACreERT2小鼠杂交，扰乱Rspo2/3基因在 骨折时的间充质祖细胞。骨愈合将使用微型CT进行评估， 组织学、分子分析和机械测试。规范的Wnt信号的改变 并将评估Rsp2/3缺陷的祖细胞的成骨能力。在Aim 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 目的1.在目标3中，Rspo2将被运送到骨损伤部位，并对BMP和WNT的影响 信号、祖细胞激活和分化，以及骨愈合评估。完成 该项目将确定Rspo2/3-Lgr6相互作用在骨折愈合中的要求，并将 为促进骨愈合提供新的治疗方向。

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.