骨髓间充质干细胞通过Notch信号通路调控肝星状细胞的作用机制研究

The activation and proliferation of hepatic stellate cells (HSCs) is the central process of liver fibrosis. Increasing evidences have favored the therapeutic potential of bone marrow-derived mesenchymal stem cells (BMSCs) for the treatment of liver fibrosis. It has been proved that bone marrow mesenchymal stem cells(BMSCs) can delay the progression of liver fibrosis by regulating the proliferation and apoptosis of actived-HSCs（aHSCs）. Our previous studies demonstrated that BMSCs might directly inhibite the proliferation of aHSCs through Notch signal pathway by cell-cell interaction,suggesting that the interaction between Notch ligands and its receptors might trigger the downstream signaling pathways and relative target genes expression concerning the proliferation and apoptosis of aHSCs. Exploring the mechanism of interaction between BMSCs and aHSCs may help more accurately regulating aHSCs. We will identify the Notch and related signaling pathways between BMSCs and aHSCs interaction in vitro, and study the relative effector molecules. The rat model of liver fibrosis will be used to investigate the efficacy of modulating Notch signaling in vivo. This study will not only provide theoretical basis for the treatment of liver fibrosis with BMSCs，but also offer more accurate targets for the treatment of liver fibrosis.

肝星状细胞(HSCs)激活和增殖是肝纤维化发生的中心环节，已有研究显示骨髓间充质干细胞(BMSCs)可通过调控活化态HSCs（aHSCs）的增殖与凋亡减轻肝纤维化的进程。我们的前期研究表明BMSCs可通过细胞直接接触激活aHSCs的Notch信号途径，抑制aHSCs增殖。提示Notch信号配体与受体的结合引发下游信号通路的改变和靶基因的表达，直接影响aHSCs的增殖与凋亡，探究BMSCs与aHSCs细胞-细胞相互作用机制有助于更精确地对aHSCs进行调控。本课题将在前期研究基础上进一步揭示参与BMSCs调控aHSCs过程中的Notch及相关信号通路的作用，确定其效应分子；并通过大鼠肝纤维化模型体内验证Notch通路及其作用分子在体内的作用。本研究不但为BMSCs治疗肝纤维化提供更直接的理论依据，也将为肝纤维化的靶向治疗提供更精确的靶点。

肝星状细胞(HSCs)激活和增殖是肝纤维化发生的中心环节，已有研究显示骨髓间充质干细胞(BMSCs)可通过调控活化态HSCs（aHSCs）的增殖与凋亡减轻肝纤维化的进程。我们的前期研究表明BMSCs可通过细胞直接接触激活aHSCs的Notch信号途径，抑制aHSCs增殖，提示Notch信号配体与受体的结合引发下游信号通路的改变和靶基因的表达，直接影响aHSCs的增殖与凋亡。探究BMSCs与aHSCs细胞-细胞相互作用机制有助于更精确地对aHSCs进行调控，故本课题旨在阐明BMSC调节aHSCs的作用机制。首先，我们发现aHSCs中细胞凋亡的诱导是由aHSCs与BMSCs直接共培养引起的，其中aHSCs中α-平滑肌肌动蛋白（α-SMA）的表达显着增加，并且它们的增殖速率增加；同时，在与BMSCs共培养的aHSC中，我们发现Hes1和Notch1的表达在蛋白质和mRNA水平上均显着增加；此外，我们通过Notch1 siRNA或DAPT处理aHSCs阻断Notch信号通路（NSP）后，发现aHSCs增殖速率提高，同时凋亡降低，并导致NF-κB信号通路的激活，而上述效应在过表达IκB S32/S36后被逆转。因此，我们的研究提示选择性抑制Notch1信号通路有望成为纤维化治疗的潜在方向，本研究不但有助于从信号转导角度更清楚地探究BMSCs治疗肝纤维化的调控机制，同时也为基于本课题发现的在抗肝纤维化中发挥关键作用的Notch1信号通路为靶点的抗纤维化新药的研发提供理论依据。