Shox2调节血管钙化的作用及机制

Vascular calcification occurs very commonly in patients with cardiovascular diseases, diabetes, and chronic kidney diseases. It is an independent risk factor for cardiovascular mortality and morbidity. Vascular calcification has been considered a regulated process resembling bone formation. However, the mechanisms underlying vascular calcification remain unclear. Therefore, it is very important for clinical treatment to elucidate the mechanisms underlying vascular calcification. Shox2 has been shown to be an important transcription factor regulating the development of heart and bone formation. Previous studies have shown that deletion of Shox2 results in severe skeletal malformations. Our preliminary data also show that Shox2 is highly expressed in calcified vascular smooth muscle cells, and overexpression of Shox2 promotes vascular smooth muscle cell calcification and up-regulates the expression of BMP2, a potent promoter of vascular calcification. Based on these findings, we hypothesize that Shox2 may regulate vascular calcification through activation of BMP2. In vitro and in vivo model of vascular calcification will be used in this study. We will use adenovirus, siRNA and knock-out techniques to investigate the role of Shox2 in vascular calcification. In addition, we will apply Chip-Seq, Chip-PCR and luciferase reporter assay to analyze the interaction between Shox2 and BMP2, and understand its mechanisms, thus providing novel theoretical basis and treatment for vascular calcification.

血管钙化常见于心血管疾病，糖尿病和慢性肾病患者，是心血管疾病发生率和死亡率增加的独立危险因素，与骨生成过程类似。但其发生机制尚不清楚，阐明血管钙化的机制具有非常重要的临床意义。Shox2是调节心脏和骨生长发育的重要转录因子。既往研究发现敲除Shox2能导致严重的骨发育障碍。我们的前期实验也表明Shox2在钙化的血管平滑肌细胞呈现高表达，过表达Shox2后能明显促进血管平滑肌细胞钙化，上调血管钙化促进因子BMP2的表达。由此我们假设：Shox2可能通过调节BMP2参与血管钙化。本项目拟采用体内和体外相结合的血管钙化模型，运用腺病毒，RNA干扰及基因敲除的方法，对Shox2是否影响血管钙化进行研究；此外，应用Chip-Seq，Chip-PCR和荧光素酶报告基因的方法，分析Shox2与BMP2的相互作用关系，阐明Shox2调节血管钙化的分子机制，为血管钙化的防治提供新的理论依据和思路。

血管钙化是类似于骨生成的过程，受基因表达调控，涉及血管平滑肌细胞成骨样分化。Shox2是调节骨生成的重要转录因子，然而Shox2在血管钙化中的作用及机制并不清楚。本项目采用血管平滑肌细胞，血管组织及动物血管钙化模型，研究了Shox2调控血管钙化的作用及机制。我们首先研究了血管钙化过程中Shox2的表达水平变化。结果显示：Shox2在血管平滑肌细胞，血管环钙化及慢性肾脏病大鼠血管钙化过程中表达水平上调。其次，我们研究了Shox2调节血管钙化的作用。细胞实验表明：过表达Shox2可促进人体和大鼠血管平滑肌细胞钙化；而敲低Shox2能明显减轻人体血管平滑肌细胞钙化。血管离体实验证明：过表达Shox2能促进大鼠和人体血管环钙化。此外，动物实验也证明过表达Shox2能加速慢性肾脏病大鼠主动脉钙化，而敲低Shox2能缓解慢性肾脏病大鼠主动脉钙化。条件性敲除血管平滑肌细胞Shox2可明显减轻小鼠主动脉钙化。最后，我们阐明了Shox2促进血管钙化的分子机制。通过转录组测序和生物学实验发现：CXCR4是Shox2的下游靶基因；抑制和敲低CXCR4可明显改善Shox2诱导的血管平滑肌细胞钙化，抑制CXCR4也能缓解Shox2诱导的大鼠主动脉钙化。以上结果表明Shox2通过上调CXCR4促进血管钙化，可为血管钙化的防治提供新的策略。