RanBP3L在BMP信号通路和间充质干细胞分化中的功能和机制研究

发布时间：2019-01-06 19:02

【摘要】：骨形成蛋白Bone Morphogenetic Proteins(BMPs)是TGF-β家族主要成员,在个体发育和维持机体骨骼肌肉系统稳态的过程中具有重要作用。BMP信号的激活和终止依赖于对BMP下游Smads蛋白(Smad1/5/8)磷酸化和核质穿梭过程的调控。本课题组之前研究发现了介导Smad1/5/8蛋白去磷酸化的磷酸酶PPM1A和SCP4,初步揭示了 BMP信号终止的机制。但是Smad1/5/8蛋白去磷酸化后如何被转运出细胞核的分子机制尚不清楚。本课题组研究发现了一个新的小G蛋白Ran的结合蛋白,命名为RanBP3L。进一步实验结果显示,RanBP3L能够特异性地识别BMP信号通路中的Smad1/5/8,并介导它们的出核运输过程。这个过程依赖于小G蛋白Ran,被转运出核的Smad1/5/8可以进一步接受下一轮BMP信号的活化。但RanBP3L并不能帮助TGF-β下游Smad2/3的出核转运。我们进一步运用荧光素酶报告系统,Real-Time PCR技术和Western技术检测发现过表达RanBP3L可以抑制BMP诱导的转录激活,并下调BMP下游基因的表达。BMP信号对间充质干细胞的分化调控具有重要作用,它可以促进间充质干细胞向骨和软骨方向分化,并抑制向肌肉方向和脂肪方向的分化。在小鼠骨髓间充质干细胞的分化模型中,RanBP3L能够调控间充质干细胞向成骨方向的分化过程,敲减RanBP3L可以显著增加骨的形成,和矿物质的沉积。此外在成肌分化过程中,RanBP3L可以通过抑制BMP信号来促进成肌细胞向肌细胞方向分化。综上所示,我们发现了一个新的BMP信号通路负向调控因子RanBP3L。它特异性介导BMP下游的Smad1/5/8蛋白的出核过程。同时参与了 BMP介导的间充质干细胞的分化过程。RanBP3L特异性地调控BMP信号通路具有重要的生理意义,为在骨骼发育异常和骨质疏松等疾病的临床治疗上提供理论基础。
[Abstract]:Bone morphogenetic protein (Bone Morphogenetic Proteins (BMPs) is a major member of the TGF- 尾 family. The activation and termination of BMP signal depends on the regulation of the phosphorylation of Smads protein (Smad1/5/8) downstream of BMP and the nucleoplasmic shuttle process. Our previous studies revealed that PPM1A and SCP4, which mediate the dephosphorylation of Smad1/5/8 protein, revealed the mechanism of BMP signal termination. However, the molecular mechanism of how the Smad1/5/8 protein is transported out of the nucleus after dephosphorylation is unclear. A new binding protein of small G protein Ran, named RanBP3L., was found by our team. Further experimental results show that RanBP3L can specifically recognize Smad1/5/8, in BMP signaling pathway and mediate their nuclear transport. This process is dependent on the activation of the next round of BMP signals by Smad1/5/8, which is transported out of the nucleus by small G protein Ran,. However, RanBP3L does not help the extranuclear transport of Smad2/3 downstream of TGF- 尾. We further use luciferase reporting system, Real-Time PCR and Western techniques to detect that overexpression of RanBP3L can inhibit transcriptional activation induced by BMP. BMP signal plays an important role in the differentiation and regulation of mesenchymal stem cells, which can promote the differentiation of mesenchymal stem cells to bone and cartilage, and inhibit the differentiation to muscle and fat. In the differentiation model of mouse bone marrow mesenchymal stem cells, RanBP3L could regulate the differentiation of mesenchymal stem cells into osteoblasts, and knockout RanBP3L could significantly increase bone formation and mineral deposition. In addition, RanBP3L can promote myoblast differentiation by inhibiting BMP signal during myogenic differentiation. In summary, we have found a new negative regulation factor of BMP signaling pathway, RanBP3L.. It specifically mediates the nucleation process of Smad1/5/8 protein downstream of BMP. It is also involved in the differentiation of mesenchymal stem cells mediated by BMP. The regulation of BMP signaling pathway by RanBP3L has important physiological significance and provides a theoretical basis for the clinical treatment of diseases such as bone dysplasia and osteoporosis.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：Q78

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