DLST的SUMO化修饰在缺氧引起的肾小管上皮细胞损伤以及肾脏纤维化过程中的功能和机制研究

Hypoxia induced Renal fibrosis is the main reason and pathological basis of many chronic kidney diseases（CKD）, however, the mechanism is still not known very well. SUMO is the hotspot of the post-translational modification field, which participate in many human diseases but few studies in CKD. We found the SUMOylation level obviously increased in the hypoxia induced HK2 cells and Renal fibrosis model-UUO mouse, which proved the significant role of SUMO during renal fibrosis process. IP/MS experiment identified an important SUMO substrate dihydrolipoyl transacetylase(DLST) , which is one of the key rate-limiting enzymes of the TCA cycle and decreased in the hypoxia induced HK2 cells and UUO mouse, revealed the metabolism handicap played an ignorable role in the Tec damage and renal fibrosis. In contrast, the interaction between SUMO and DLST had a sensational level up in the same process, which strongly suggested that the SUMOylation down-regulated DLST expression and consequently led to metabolism handicap and then resulted in the Tec damage and renal fibrosis. Our group will completely characterize the detailed mechanism of DLST SUMOylation and clarify its exact effect during hypoxia induced Renal fibrosis, which may provide a novel therapeutic approach for related diseases.

慢性缺氧始动的肾间质纤维化是多类慢性肾脏病（CKD）进展至终末期的共同病理表现，其分子机制尚未完全阐明。类泛素小蛋白（SUMO）是蛋白质翻译后修饰领域的研究热点，广泛参与人类疾病，但在CKD的研究还很匮乏。我们前期发现，SUMO化在缺氧诱导的肾小管上皮细胞（HK2）以及肾纤维化小鼠模型（UUO）中高表达,证明SUMO化在肾纤维化中发挥了重要作用。IP/MS等实验进一步发现三羧酸循环中的关键限速酶二氢硫辛酰琥珀酰转移酶（DLST）是SUMO化底物,其在缺氧诱导的HK2及UUO中表达降低，说明能量代谢障碍在肾纤维化中的重要影响，同时其SUMO化程度却显著上升，强烈提示SUMO化通过负调控DLST，导致能量代谢障碍并引起肾小管上皮细胞损伤及肾脏纤维化。本课题组将彻底研究DLST的SUMO化的详细机制，阐明这一过程引起的能量代谢障碍在缺氧始动的肾纤维化中的作用，为相关疾病的治疗提供新的角度和思路。

慢性缺氧始动的肾间质纤维化是多类慢性肾脏病（CKD）进展至终末期的共同病理表现，其分子机制尚未完全阐明。类泛素小蛋白（SUMO）是蛋白质翻译后修饰领域的研究热点，广泛参与人类疾病，但在CKD的研究还很匮乏。我们研究发现，SUMO本身以及SUMO化的蛋白在缺氧诱导的肾小管上皮细胞（HK2）以及肾纤维化小鼠模型（UUO）中均高表达,证明SUMO化在肾纤维化中发挥了重要作用。通过IP/MS等实验（三次重复）进一步发现三羧酸循环中的关键限速酶二氢硫辛酰琥珀酰转移酶（DLST，ɑ酮戊二酸脱氢酶系的酶2）是SUMO化底物,其在缺氧诱导的HK2及UUO中表达降低，说明能量代谢障碍在肾纤维化中的重要影响，同时其SUMO化程度却显著上升，强烈提示SUMO化通过负调控DLST，导致能量代谢障碍并引起肾小管上皮细胞损伤及肾脏纤维化。后续在深入研究中进一步通过过表达/干预等实验，进一步验证了DLST的在间质纤维化过程中的重要作用，同时对DLST的SUMO化机制在体内外进行了深入研究。本项目通过对DLST的SUMO化及其在慢性缺氧诱导的肾间质纤维化机制的研究，揭示了DLST的SUMO化这一过程引起的能量代谢障碍在缺氧始动的肾纤维化中的作用，为相关疾病的治疗提供新的角度和思路。