肾胺酶与多巴胺D1类受体相互作用致盐敏感肾脏钠代谢紊乱的机制研究

Renal sodium metabolism is the important process in the formation of salt sensitive hypertension. Dahl salt-sensitive rats fed with high-salt diet showed decreased expression of D1-like receptor and dysfunction in kidney, which affecting sodium transport of renal proximal tubule, and eventually increased the blood pressure. Renalase that is secreted by the kidneys is reported to participate in the abnormalities of Dopamine D1 receptor expression and function. Through Dahl salt-sensitive rats and an interventional study previously, we firstly discovered that renalase may be involved in the formation of salt-sensitive hypertension. Herein, we put forward the hypothesis “the interactions between renalase and dopamine D1-like receptor may play a vital role in renal dysfunction metabolism of sodium in salt-sensitive rats”. Firstly, using the animal models of Dahl salt-sensitive rats, knockout mice, CRISPR/Cas9 system and gene overexpression, we explore the renal expression of renalase and dopamine D1-like receptor, physical connection, coexistence as well as its impact on the sodium ion transport. Additionally, we further use mammalian two-hybrid approach to explore the binding site of renalase in this interaction at the cellular level. Finally, the relationship between this interaction and PLC/IP3/PKC, MAPK signaling would be validated in molecular level. We believe that this work would be of great significance to uncover the etiology of salt sensitive hypertension as well as to seek another drug targets for treatment of essential hypertension.

肾脏钠代谢障碍是盐敏感高血压形成的重要环节。Dahl盐敏感大鼠在高盐负荷后出现肾脏多巴胺D1类受体表达降低、功能障碍，影响钠离子转运，导致血压的升高。最新研究发现，肾脏中分泌的一种肾胺酶可能与多巴胺D1类受体的表达和功能异常密切相关。本项目在我们前期通过Dahl盐敏感大鼠和人群干预实验首次发现肾胺酶参与盐敏感高血压形成的基础上，提出“肾胺酶与多巴胺D1类受体的相互作用是盐敏感肾脏钠代谢紊乱的重要环节”的假设，首先拟采用Dahl盐敏感大鼠、基因敲除小鼠、基因敲除或过表达技术，在动物或细胞水平研究肾胺酶、多巴胺D1类受体的表达，两者的物理连接与共存情况以及对钠离子转运的影响。进一步在细胞水平上采用哺乳动物双杂交方法探索肾胺酶发生相互作用的具体部位。最后在分子水平上验证PKC，MAPK通路与两者相互作用的关系。本研究对进一步揭示盐敏感性高血压的分子遗传学机制，寻找新的高血压药物靶点具有重要意义。

原发性高血压是遗传与环境因素长期相互作用所致的疾病，钠盐是最重要的环境因素之一，与血压存在剂量效应关系。盐敏感性是个体血压对盐的遗传易感性，是原发性高血压的一种中间遗传表型。高盐摄入可升高血压，并导致心肌梗死、左心室肥大，慢性肾病以及血管功能障碍等靶器官损伤。此外，高盐也可独立于血压升高之外造成靶器官损害。然而，关于高盐负荷后产生独立于血压之外的靶器官损伤的机制尚不清楚。肾胺酶是新近发现的一种由肾脏分泌依赖于黄素腺嘌呤二核苷酸的胺氧化酶，具有降解儿茶酚胺，调节血压、保护肾脏及心肌组织等功能。本研究发现肾胺酶多个基因多态性位点与远期血压变化、高血压的发生密切相关，进一步我们从血清学角度和肾脏表达方面证实肾胺酶参与高血压的发生发展过程。此外，本研究还发现，高盐饮食显著上调肾组织RIP1、RIP3和MLKL表达，促进Necroptosis的发生，导致细胞坏死，释放大量炎症因子，促使细胞外基质增多、纤维化的形成，最终导致肾脏损伤，而重组肾胺酶则可逆转上述改变，保护肾脏功能。最后我们研究提示，血浆尿酸可能参与盐敏感性的病理生理过程，且尿尿酸与亚临床肾损伤密切相关。本项目对揭示盐、盐敏感靶器官损伤的分子机制，寻找新的高血压药物靶点具有重要意义。