RUNX@ Subnuclear Targeting Integrates Signaling Pathways for Bone Formation

Runx 2是一种支架蛋白，可与代表许多不同功能类别的蛋白质相互作用， 包括染色质重塑因子、与细胞生长控制偶联的蛋白质、成骨细胞的分化 和骨基质的产生，以及那些抑制发育信号通路的蛋白质， 促进骨骼形成。我们已经确定，Runx 2招募到其亚核结构域， 核基质，信号传导途径的细胞内介质，其是细胞增殖的正调节剂和负调节剂。 骨形成，包括响应BMP/TGF β的Smads，和响应BMP/TGF β的WW结构域蛋白雅普， Src信号。我们已经定义了Runx 2蛋白中的特定点突变，这些突变可以破坏这些关键的 Runx 2和Smad以及Runx 2与WW结构域蛋白之间的相互作用，其中包括不断增长的 影响Runx 2对靶基因活性的因素很多。这些点突变使我们能够解决 这些相互作用在小鼠基因敲入模型的核微环境中的体内意义。我们 影响成骨细胞分化的miRNA的发现使我们能够解决微RNA（miRNA）如何影响成骨细胞分化的问题。 靶向Runx 2和Runx 2辅因子通过修饰形成骨的蛋白质来调节骨形成， 核中的Runx 2共调节复合物。项目2现在将探讨这些多重信号是如何 在成骨细胞分化过程中，会聚于Runx 2的途径受到调节，以控制骨 阵我们将1）表征Runx 2-Smad靶基因和完成所需的调控复合物 BMP 2成骨信号; 2）表征影响骨形成的生物学机制和信号通路， WW共调节蛋白与Runx 2的组织以控制骨生成;以及目的3）研究 靶向Runx 2和共调节因子的miRNA候选物如何调节骨生成。 临床相关性：迫切需要开发合成代谢疗法来治疗骨丢失， 骨质疏松症是由骨骼老化或继发于代谢性骨骼疾病引起的。我们的研究将 定义新的靶点，在响应BMP时产生新的骨，将干细胞分化转向 成骨细胞谱系和鉴定的骨形成的miRNA调节剂。每一个都代表着 刺激成骨细胞分化和骨形成的治疗应用。例如，siRNA和 正在开发用于体内应用的miRNA技术。合成代谢疗法比 可以开发激素治疗来刺激骨形成。

Runx2 is a scaffolding protein that interacts with proteins representing many different functional classes, including chromatin remodeling factors, proteins coupled to cell growth control, differentiation of osteoblasts and production of bone matrix, as well as those proteins that transduce developmental signaling pathways for bone formation. We have established that Runx2 recruits to its subnuclear domains associated with the nuclear matrix, intracellular mediators of signaling pathways that are both positive and negative regulators of bone formation, including Smads in response to BMP/TGF(3, and YAP, a WW domain protein in response to Src signaling. We have defined specific point mutations in the Runx2 protein that can disrupt these critical interactions between Runx2 and Smad and Runx2 with WW domain proteins, which include a growing number of factors that influence Runx2 activity on target genes. These point mutations allow us to address the in vivo significance of these interactions in nuclear microenvironments in mouse knock-in models. Our discovery of miRNAs that affect osteoblast differentiation leads us to address how micro-RNAs (miRNA) that target Runx2 and Runx2 co-factors regulate bone formation through modification of the proteins that form Runx2 coregulatory complexes in the nucleus. Project 2 will now pursue how these multiple signaling pathways which converge on Runx2 are regulated during osteoblast differentiation for the control of bone formation. We will 1) characterize Runx2-Smad target genes and regulatory complexes required to complete the BMP2 osteogenic signal; 2) characterize the biological mechanisms and signaling pathways influencing the organization of WW coregulatory proteins with Runx2 to control osteogenesis; and Aim 3) investigate how miRNA candidates that target Runx2 and coregulatory factors regulate osteogenesis. Clinical Relevance: There is a pressing need to develop anabolic therapies for treating bone loss in osteoporosis from the aging skeleton or induced secondary to a metabolic bone disorder. Our studies will define novel targets that produce new bone in response to BMPs, shift the stem cell differentiation towards the osteoblast lineage and identify miRNA regulators of bone formation. Each of these represents potential therapeutic applications to stimulate osteoblast differentiation and bone formation. For example, siRNA and miRNA technologies are being developed for in vivo application. Anabolic therapies that are safer than hormone treatments could be developed for stimulating bone formation.