Smad4在第二生心区Six2+来源细胞中调控vWF-Notch信号通路参与动脉导管关闭的机制研究

Although investigations of molecular mechanisms of patent ductus arteriosus (PDA) are broadly conducted, the reciprocal interaction between vascular smooth muscle cells (SMCs) and endothelial cells (ECs) from DA progenitor cells remain unclear. Our pervious study found the Six2+ cells from the second heart field (SHF) can migrate to DA and differentiate into SMCs and ECs in mice. In Six2GC/+; Smad4F/F mice there were a defect of DA wall thickening, a large DA lumen with decreased expression of SMCs contractile markers, and a decrease of vWF expression in ECs. With bioinformatics 4 potential binding sites between SMAD4 and promotor region of Vwf were predicted. vWF can inhibit expression of SMCs contractile markers by negatively regulating Notch signaling pathway. Here we hypothesized that Smad4 in Six2+ cells from SHF can regulate the expression of vWF in ECs and accordingly affect the Notch signaling pathway, leading to the pathogenesis of PDA with abnormal function of SMCs. This study was designed from the levels of molecular, cells, animal model and 3D reconstruction to investigate the correlation between PDA and mouse model, the relationship of SMCs function and vWF-Notch signaling, and to confirm the binding sites between SMAD4 and promotor region of Vwf in cells. Our study may shed light on new targets for PDA treatments.

动脉导管未闭机制研究众多，但动脉导管DA祖细胞来源的血管平滑肌（SMCs）和内皮细胞（ECs）相互作用机制尚不明确。前期研究发现小鼠第二生心区Six2+细胞可迁移分化为DA SMCs和ECs；Six2GC/+; Smad4F/F小鼠模型中DA血管壁变薄，管腔扩大，SMCs收缩相关性蛋白表达降低，ECs vWF表达降低，生物信息学预测出4个SMAD4与Vwf启动子区潜在结合位点。vWF可抑制Notch信号通路而抑制SMCs收缩相关性蛋白表达，据此我们提出假说：Smad4在第二生心区Six2+来源细胞中可直接通过调控vWF表达影响Notch信号通路、导致SMCs功能异常等而致PDA。本课题拟从分子、细胞、动物水平、3D重建等方面明确PDA与动物模型的相关性，阐明DA血管SMCs功能和vWF-Notch信号通路的关系，证实Smad4调控vWF表达的作用方式与关键位点，为PDA防治提供新思路。

动脉导管未闭（PDA）机制研究众多，但动脉导管（DA）祖细胞来源的血管平滑肌（Smooth Muscle Cells, SMCs）和内皮细胞（Endothelial Cells, ECs）在DA关闭中的相互作用机制尚不明确。前期研究发现小鼠第二生心区Six2+细胞可迁移分化为DA SMCs和ECs，课题建立了Six2GC/+; Smad4F/F小鼠模型，发现小鼠DA血管壁厚度变薄，管腔扩大，SMCs数量减少，且ECs血管性血友病因子（von Willebrand Factor, vWF）表达降低，生物信息学预测出4个SMAD4与Vwf启动子区结合的潜在位点。vWF可促进小鼠主动脉SMCs增殖，又可抑制Not ch信号通路抑制SMCs分化，据此我们提出假说：Smad4在第二生心区SIX2+细胞中可直接通过调控ECs VWF表达影响Notch信号通路，导致SMCs和ECs功能异常等而导致PDA。本课题拟从分子、细胞、动物水平、3D重建等方面明确小鼠模型与PDA的相关性；阐明DA血管SMCs表型改变、增殖/凋亡、对Notch等相关通路的影响；证实Smad4调控vWF表达的作用方式与关键位点，从而阐明假说的具体分子机制。本研究将从Smad4和vWF的相互作用探讨DA的发育和关闭，为PDA防治提供新思路。