Lin Weiyuan, Shi Shanhong, Zheng Yanling, Cui Jiong, Wan Jianxin
Department of Nephrology, Blood Purification Research Center, The First Affiliated Hospital, Fujian Medical University, Fuzhou, 350005, China; Department of Nephrology, The Second Affiliated Hospital, Fujian Medical University, Quanzhou, 362000, China.
Department of Nephrology, The Second Affiliated Hospital, Fujian Medical University, Quanzhou, 362000, China.
Exp Cell Res. 2025 Jul 15;450(2):114631. doi: 10.1016/j.yexcr.2025.114631. Epub 2025 Jun 2.
Krüppel-Like Factor 15 (KLF15) is a member of the Krüppel-like subfamily of zinc finger transcription factors, involved in a diverse renal physiology and diseases. The exact roles of KLF15 in IgA nephropathy (IgAN) have not been fully investigated. To address the issue of KLF15 expression and its exact roles in IgAN, IgAN mouse models and IgA-treated podocytes MPC-5 were established. Co-immunoprecipitation (Co-IP) assay was conducted to detect the interaction between KLF15 and p300. Levels of genes and complement factors were determined by Western blot, immunofluorescence, immunohistochemistry and ELISA assays. Podocytes apoptosis was detected with flow cytometry. KLF15 expression was downregulated in both renal tissues of IgAN mouse models and IgA-treated podocytes. This suppression coincided with elevated levels of complement components C3a and C5a, along with increased complement factor H (CFH) expression, collectively suggesting activation of the complement activation in IgA nephropathy. Besides, NF-κB was activated in IgAN, evidenced by the elevated levels of NF-κB p65 and its acetylation at lysine 310 as well as IκBα phosphorylation in IgAN models and IgA-treated podocyte. KLF15 overexpression alleviated complement activation and IgAN podocyte injury, characterized by improved cell viability, reduced apoptotic cells and apoptotic proteins expression (Bax/Bcl-2 and cleaved-caspase3), upregulated expression of nephrin and podocin, and suppressed complement components. In terms of mechanism, KLF15 overexpression could inhibit NF-κB activation by interacting with p300 to decrease p300 level, which was further confirmed by using p300 activator CTB or NF-κB activator PMA. These results indicate that KLF15 protects against podocyte injury in IgA nephropathy by suppressing complement system activation and modulating the p300/NF-κB signaling axis.
Krüppel样因子15（KLF15）是锌指转录因子Krüppel样亚家族的成员，参与多种肾脏生理功能和疾病过程。KLF15在IgA肾病（IgAN）中的确切作用尚未得到充分研究。为了解决KLF15在IgAN中的表达及其确切作用问题，建立了IgAN小鼠模型和经IgA处理的足细胞MPC-5。进行了免疫共沉淀（Co-IP）分析以检测KLF15与p300之间的相互作用。通过蛋白质免疫印迹、免疫荧光、免疫组织化学和酶联免疫吸附测定（ELISA）分析来测定基因和补体因子的水平。用流式细胞术检测足细胞凋亡。在IgAN小鼠模型的肾组织和经IgA处理的足细胞中，KLF15表达均下调。这种抑制与补体成分C3a和C5a水平升高以及补体因子H（CFH）表达增加同时出现，共同提示IgA肾病中补体激活被激活。此外，在IgAN中NF-κB被激活，IgAN模型和经IgA处理的足细胞中NF-κB p65水平升高及其赖氨酸310位点的乙酰化以及IκBα磷酸化证明了这一点。KLF15过表达减轻了补体激活和IgAN足细胞损伤，其特征为细胞活力改善、凋亡细胞和凋亡蛋白表达（Bax/Bcl-2和裂解的半胱天冬酶3）减少、nephrin和podocin表达上调以及补体成分受到抑制。在机制方面，KLF15过表达可通过与p300相互作用以降低p300水平来抑制NF-κB激活，使用p300激活剂CTB或NF-κB激活剂PMA进一步证实了这一点。这些结果表明，KLF15通过抑制补体系统激活和调节p300/NF-κB信号轴来保护IgA肾病中的足细胞免受损伤。
