近端小管S3段Arg2调控NF-κB信号通路在AKI向CKD转变中的作用与机制研究

急性肾损伤(AKI)与慢性肾脏病(CKD)的发生发展关系密切。目前尚无明确方法防治AKI向CKD转变。我们前期研究证实精氨酸酶2(Arg2)定位于肾脏近端小管S3段，通过促进炎症在CKD中发挥重要作用，但机制不明。预实验发现：Arg2在肾脏缺血再灌注损伤后高表达；TNF-α上调Arg2；Arg2促进NF-κB激活，参与TNF-α诱导的炎症。在上述基础上，申请人提出科学假说：近端小管S3段Arg2在线粒体中与p50、p65、IκBα相互作用，调控其在线粒体与细胞浆间的穿梭，促进NF-κB激活，加剧TNF-α诱导的炎症，介导AKI向CKD转变。本课题拟运用CRISPR/Cas9敲除和腺病毒转染过表达等手段，联合免疫荧光、免疫共沉淀等技术，利用人近端小管细胞系及近端小管S3段特异性Arg2基因敲除小鼠的缺血再灌注损伤模型验证该假说，为防治AKI向CKD转变提供新的S3段潜在特异靶点。

Acute kidney injury(AKI) is highly associated with the occurrence and development of chronic kidney disease(CKD). Currently, there are no established therapeutic interventions to prevent or treat the AKI-to-CKD transition. Our previous studies demonstrated that arginase 2(Arg2) is localized in the proximal tubule S3 segment and plays an important role in CKD by promoting renal inflammation. However, the underlying mechanism is unknown. Our preliminary experiments showed that Arg2 expression is upregulated after renal ischemia reperfusion injury, TNF-α induces Arg2 expression, and Arg2 promotes activation of NF-κB signaling pathway, contributing to TNF-α-induced inflammation. Based on these results, we hypothesize that proximal tubule S3 segment Arg2 enhances TNF-α-induced NF-κB activation by interacting with mitochondrial p50、p65、IκBα and modulating their trafficking between mitochondria and cytosol, thereby promoting renal inflammation, finally leading to the AKI-to-CKD transition. To verify our scientific hypothesis, we will utilize CRISPR/Cas9 gene knockout system and adenovirus transfection methods in combination with immunofluorescence staining and immunoprecipitation technique in human proximal tubule epithelial cells and establish renal ischemia reperfusion injury model in proximal tubule S3 segment specific Arg2 knockout mouse. Our study may provide novel S3 segment specific therapeutic target for the AKI-to-CKD transition.