Notch-EphB4-Cav-1信号通路在高血压大鼠脑静脉功能和重构中的作用

The brain injuries brought about by the cerebral venous lesions are receiving more and more attention, for example, cerebral venous infarction or hemorrhage could result in hemiparesis, dementia,epilepsy, and other serious consequences. As an important risk factor of cerebrovascular disease, the mechanism of hypertensive cerebral venous changes are remain unclear. Studies have shown that expression of EphB4 is down-regulated after activation of Notch signaling. Also, it is demonstrated that EphB4 can affect cell migration and the thickness of the vessels,through regulating the expression or activity of Cav-1. Our previous study found that the walls of the cerebral vein from the hypertensive rats are thickened,which are mainly collagen proliferation and deposition, and that EphB4 expression of the cerebral veins and p-Cav1 expression of the vein endothelial cells of are dowe-regulated. Then, if the Notch-EphB4-Cav-1 signaling is invovled in the mechanism or not? In our study,we aim to observe the structural and functional changes of the cerebral vein from hypertensive rats.Also we aim to explore the interlationships of Notchs, EphB4, Cav-1, and the downstream tagets by gene silencing of related genes oriented by a two-photon microscope. Further, by means of the technologies such as gene knockdown, immunoprecipitation and so on, we try to expound the specific molecular mechanism of underlying hypertensive cerebral venous disease in cell models, and hope to provide theoretical guidance and fundational study for new preventation and treatment of hypertensive cerebral venous diseases.

脑静脉病变导致的脑损害正被关注和重视,如静脉性脑梗死、静脉性脑微出血等可导致偏瘫、痴呆、癫痫等严重后果。高血压作为脑血管病发生的重要危险因素，是否引起脑静脉病变及相关机制尚不清楚。研究表明，激活Notch信号后EphB4表达受到抑制。而EphB4可调控Cav1表达和活性，影响细胞迁移、静脉移植物管壁增厚等血管重构过程。我们的前期研究发现，高血压大鼠脑静脉管壁重构以胶原增生为主，同时其静脉内皮EphB4、p-Cav1蛋白表达降低。那么Notch-EphB4-Cav1通路是否参与高血压脑静脉的重构？我们拟在高血压大鼠模型，观察其脑静脉的功能和结构改变，并采用双光子显微鏡定位脑静脉在局部对相关基因进行基因沉默，探讨Notch、EphB4、Cav1及下游信号分子彼此间的相互关系；同时，在体外高血压细胞模型上，通过细胞基因敲除、免疫沉淀等技术，研究其分子机制，为高血压脑静脉病变的防治提供研究基础。

高血压所致脑静脉病变，如静脉窦血栓、静脉性脑梗死/脑微出血、脑室周围静脉胶原病等可导致偏瘫、痴呆、癫痫等严重后果；其引起的脑损害越来越被人们所关注和重视。但具体的病变机制尚不清楚。. 我们应用RHRSP高血压大鼠模型，观察活体高血压大鼠脑静脉的血流动力学情况及脑静脉的病理改变。结果显示：高血压组大鼠脑皮质静脉数增多，表现出血流速度减慢、单位时间内血流量显著减少。脑静脉内皮基膜连续性被破坏；静脉外周神经肿胀；呈现脑白质疏松改变。以上结果验证了高血压这一危险因素对脑静脉病变的影响。. 我们在进一步研究高血性脑静脉结构和功能改变特点的时候发现：高血压发生时，具有静脉血管保护作用的Cav-1蛋白在颈静脉表达减少，基质降解增多，代表血管重构、血管壁增厚的细胞因子MMP9等表达增多。这就进一步阐明了高血压条件下颈静脉血管重构、血管壁增厚的生化基础。在脑静脉血管内皮细胞模型上我们进一步验证Notch-EphbB4-Cav-1信号通路在高血压条件下的血管重构中发挥的作用；结果表明：①高血压组Cav-1、Notch-1及血管重构相关因子Collagen I、MMP2、MMP9表达水平均明显增高。②siRNA干扰敲低Cav-1基因表达后，增加了高血压组细胞活性、减少了细胞凋亡；且血管重构相关因子Collagen I、MMP2、MMP9表达明显降低。③高血压组与对照组相比，Notch-1蛋白表达增高；采用siRNA干扰敲低Cav-1基因表达或添加Notch抑制剂DAPT后，降低了Notch-1蛋白的表达、增加了高血压组细胞活性、减少了细胞凋亡；同时血管重构相关因表达明显降低。以上结果揭示了高血压性脑静脉病变发生的可能细胞分子机制：表明高血压条件下，脑静脉内皮细胞Cav-1表达增高，激活了Notch信号传导通路，增加Collagen I、MMP2、MMP9表达；参与了血管重构。