EGFR信号通路通过Egr2促进骨祖细胞增殖并抑制骨祖细胞凋亡的实验性研究

发布时间：2019-06-28 15:51

【摘要】：骨组织结构完整性的维持依赖于骨祖细胞池中成骨细胞的不断更新,该生物学过程由许多生长因子进行精细调控。表皮生长因子受体(EGFR)配体是目前已知的骨祖细胞有丝分裂原。但这些配体调节骨祖细胞池的具体机制没有得到详细阐述,尤其是EGFR信号通路在调节骨祖细胞凋亡中的作用没有得到详细研究。在本研究中,我们证实了EGFR信号通路的激活通过促进骨祖细胞增殖并抑制骨祖细胞凋亡,增加骨祖细胞数量。该结论在大鼠颅骨组织器官培养实验中得到进一步证实。在大鼠颅骨组织器官培养实验中,表皮生长因子(EGF)在增加增殖细胞数量的同时,降低了凋亡细胞数量,从而增加成骨细胞总数量。骨祖细胞系MC3T3细胞Microarray分析提示,EGFR信号通路能诱导抗凋亡基因Mcl1以及早期生长反应基因(Egr1, Egr2, Egr3)的表达。过表达Egrs的抑制蛋白Nab2可抑制EGF诱导的骨祖细胞数量增加。进一步实验表明,以SiRNA降低Egr2的表达,可抑制EGF诱导的骨祖细胞数量增加,而以SiRNA降低Egrl、Egr3的表达,则对EGF诱导的骨祖细胞数量增加没有影响。进一步研究证实Egr2是EGF促进骨祖细胞增殖并抑制骨祖细胞凋亡的主要介导基因。采用腺病毒过表达、抑制剂以及SiRNA等实验方法,我们证实了EGFR信号通路激活MAPK/Erk通路,进而诱导Egr2的表达,从而导致了Mcll的增加,最终抑制细胞凋亡。同时,另一骨祖细胞有丝分裂原和存活因子成纤维细胞生长因子(FGF)2,也能通过诱导Egr2的表达,进而促进骨祖细胞增殖,抑制骨祖细胞凋亡。这些结果表明,Egr2在生长因子介导的骨祖细胞数量增加中起着重要作用。总的来说,我们的实验结果清楚地说明了EGFR信号传导通路,通过诱导Egr2的表达,促进骨祖细胞增殖,抑制骨祖细胞凋亡,进而在调节骨祖细胞库的生物学功能中,起着重要的作用。
[Abstract]:The maintenance of the structural integrity of the bone tissue depends on the continuous update of the osteoblast in the bone progenitor cell, which is finely regulated by a number of growth factors. The epidermal growth factor receptor (EGFR) ligand is currently known as the mitogen of the bone progenitor cells. However, the specific mechanism of these ligands for modulating the pool of bone progenitor cells is not described in detail, in particular the role of the EGFR signaling pathway in the regulation of the apoptosis of the bone progenitor cells. In this study, we confirmed the activation of the EGFR signaling pathway by promoting the proliferation of bone progenitor cells and inhibiting the apoptosis of the bone progenitor cells and increasing the number of bone progenitor cells. The conclusion is further confirmed in the experiment of rat skull tissue organ culture. In the experiment of rat skull tissue organ culture, the epidermal growth factor (EGF) increased the number of proliferating cells and decreased the number of apoptotic cells, thus increasing the total amount of osteoblast. Microarray analysis of the cell line MC3T3 cells suggested that the EGFR signaling pathway could induce the expression of anti-apoptotic gene Mcl1 and early growth response genes (Egr1, Egr2, Egr3). The inhibition protein Nab2 over-expression of Egrs can inhibit the increase in the number of EGF-induced bone progenitor cells. Further experiments show that the expression of Egr2 is reduced by SiRNA, and the increase of the amount of the EGF-induced bone progenitor cells can be suppressed, and the increase of the amount of the EGF-induced bone progenitor cells is not affected by the reduction of the expression of Egrl, Egr3 in the SiRNA. Further studies have shown that Egr2 is a major mediating gene for EGF to promote the proliferation of bone progenitor cells and to inhibit the apoptosis of bone progenitor cells. Using the method of adenovirus overexpression, inhibitor and SiRNA, we confirmed the activation of the MAPK/ Erk pathway in the EGFR signaling pathway, and further induced the expression of Egr2, which resulted in an increase of Mcll, which ultimately inhibited the apoptosis of the cells. At the same time, the other bone progenitor cell mitogen and the survival factor fibroblast growth factor (FGF)2 can also promote the proliferation of the bone progenitor cells and inhibit the apoptosis of the bone progenitor cells by inducing the expression of the Egr2. These results indicate that Egr2 plays an important role in the growth factor-mediated increase in the number of bone progenitor cells. In general, our experimental results clearly illustrate the EGFR signaling pathway and play an important role in the regulation of the biological function of the bone progenitor cell by inducing the expression of Egr2, promoting the proliferation of the bone progenitor cells, and inhibiting the apoptosis of the bone progenitor cells.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2012
【分类号】：R329

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