Syndecan-1/VEGFR-2在急性缺血性肾小球内皮细胞损伤中的作用及机制

The mechanism of acute ischemic glomerular endothelial cell injury is not entirely clear. We found that, Syndecan-1 was significantly decreased in glomerular endothelial cells when treated with hypoxia-mimicking agent cobalt chloride (CoCl2), whereas Dab2 phosphorylation was increased greatly in the treated group compared with control, but the effects of these changes is unknown and need further research. Syndecan-1 is involved in endocytosis through regulating the expression of VEGFR-2 in multiple myeloma endothelial cells. We speculated that, Syndecan-1 could protect the glomerular endothelial cells from acute ischemic injury by regulating the VEGFR-2 associated endocytosis. Based on the above analysis, the present research is to explore the effects of Syndecan-1 on the expression of Dab2/PAR-3, and its protective effects on glomerular endothelial cells; Then, we will further study the mechanism of Dab2/PAR-3 in Syndecan-1 mediated VEGFR-2 associated endocytosis using co-immunoprecipitation, etc; Last but not the least important, we will clarify the expression of Syndecan-1 and VEGFR-2 associated endocytosis in acute ischemic kidney injury in vivo. This project is of great clinical value and practical significance as it will identify new targets and provide theoretical basis for early diagnosis and treatment of glomerular endothelial cell dysfunction and acute ischemic kidney injury.

急性缺血性肾小球内皮细胞受损机制不完全清晰。我们发现，氯化钴诱导低氧降低肾小球内皮细胞Syndecan-1表达，伴Dab2磷酸化增加，但作用不明。Syndecan-1通过调控骨髓瘤血管内皮细胞VEGFR-2表达，参与细胞的内吞作用。我们推测，Syndecan-1通过调控VEGFR-2参与的内吞作用阻断急性缺血性肾小球内皮细胞损伤。基于上述分析，本课题拟通过质粒转染、RNA干扰等技术研究Syndecan-1在Dab2/PAR-3表达及其对肾小球内皮细胞的保护作用；其次，利用免疫共沉淀等进一步探讨Dab2/PAR-3在Syndecan-1介导VEGFR-2内吞作用中的机制；最后，通过体内试验阐明急性缺血性肾损伤对肾小球内皮细胞Syndecan-1表达及VEGFR-2内吞作用的影响，从而为肾小球内皮细胞损伤修复及缺血性急性肾损伤的早期诊断与治疗提供新靶点和理论依据，具有重要的临床价值和实践意义。

急性缺血性肾小球内皮细胞受损机制不完全清晰。我们前期研究发现，氯化钴诱导的低氧可降低肾小球内皮细胞Syndecan-1的表达，伴Dab2磷酸化增加，但作用不明。Syndecan-1通过调控骨髓瘤血管内皮细胞VEGFR-2的表达，参与细胞的内吞作用。我们推测，Syndecan-1通过调控VEGFR-2参与的内吞作用阻断急性缺血性肾小球内皮细胞损伤。我们在研究中发现，Syndecan-1表达下调可通过阻断VEGF-VEGFR-2通路的激活导致肾小球内皮细胞结构与功能受损。网格蛋白介导的VEGFR-2参与的内吞作用在VEGF-VEGFR-2通路表达过程中发挥重要作用，小窝蛋白介导的内吞作用对VEGF-VEGFR-2通路发挥负调控作用。敲低肾小球内皮细胞Syndecan-1的表达下调可诱导VEGFR-2参与小窝蛋白介导的内吞作用，阻断网格蛋白介导的VEGFR-2参与的内吞作用，从而抑制VEGF-VEGFR-2通路的表达。Dab2/PAR-3在网格蛋白介导的内吞作用中发挥重要作用。Dab2或PAR-3的表达下调可阻断VEGF-VEGFR-2通路的表达。Syndecan-1表达下调对Dab2与PAR-3在mRNA及蛋白表达水平上均无明显差异，但可通过诱导aPKC的活化导致Dab2磷酸化增加。磷酸化Dab2可负调控VEGF-VEGFR-2通路表达，故我们推测，Syndecan-1的表达下调可通过诱导aPKC介导的Dab2磷酸化阻断VEGF-VEGFR-2通路的表达，从而导致肾小球内皮细胞损伤。这为肾小球内皮细胞损伤修复及缺血性急性肾损伤的早期诊断与治疗提供新靶点和理论依据，具有重要的临床价值和实践意义。