SNX19与GRK4竞争调节肾脏多巴胺D1受体磷酸化在高血压病发生中的作用与机制研究

肾脏多巴胺D1R功能障碍是高血压发生的关键环节，胞膜分布减少是其功能降低的重要原因，但机制尚不清楚。SNX19因与D1R共连接引起关注，前期发现SNX19全身敲除小鼠血压升高，伴肾脏D1R胞膜分布降低；敲低肾近曲小管（RPT）细胞SNX19后，D1R的钠泵抑制作用减弱，表明其可调节D1R功能。既往报道磷酸化影响D1R胞内分布，我们发现敲低SNX19增强D1R磷酸化；高血压下肾脏SNX19表达降低，D1R与其调节激酶GRK4连接增强；恢复其表达逆转D1R磷酸化；分子对接技术预测三者有共结合区域，提示SNX19和GRK4可能竞争结合D1R。推测高血压下肾脏SNX19表达降低，促使GRK4与D1R结合增多，引发其过度磷酸化、D1R胞膜表达与功能降低，导致血压升高。拟利用肾脏特异敲除SNX19小鼠及其RPT细胞研究SNX19与GRK4对D1R磷酸化的竞争调节，阐明高血压下D1R细胞分布异常的原因。

The dysfunction of renal dopamine D1 receptor (D1R) plays a vital role in the development of hypertension. The decreased expression of D1R in the cell membrane is an important cause; however, its mechanism still remains unclear. Sorting nexin 19 (SNX19) drews our attention for its direct connection with D1R. Our previous studies found that in SNX19 global knockout mice, the blood pressure was increased, and the expression of membranal D1R in the kidney is decreased; after knockdown of SNX19 expression in the renal proximal tubule (RPT) cells, D1R-madiated inhibition of Na+ pump was impaired, indicating that SNX19 can regulate the functions of D1R. Intracellular distribution of D1R is modulated by its phosphorylation. Our previous studies found that knockdown of SNX19 expression in the RPT cells increased D1R phosphorylation; in the hypertensive status, the expression of renal SNX19 was decreased, as well as the connection between D1R and G protein-coupled receptor kinase 4 (GRK4) was increased; D1R rescue restored the hyper-phosphorylated D1R. Molecular docking technique predicted that there may be a binding domain among D1R, SNX19 and GRK4, suggesting that SNX19 and GRK4 may competitively bind with D1R. Thus, our hypotheses is that in the hypertensive status, the decreased renal SXN19 expression leads to the increased connection between GRK4 and D1R, inducing D1R hyperphosphorylation, and then impairs its membranal expression and functions, causing the increased blood pressure. Based on the above, we plan to study the competitive regulation of SNX19 and GRK4 on the phosphorylation of renal D1R in the renal SNX19 conditional knockout mice, and illustrate the cause of abnormal membranal and intracellular distribution of D1R in the hypertensive status.