RATIONALE Tubulointerstitial fibrosis, which is closely related to functional injury of the kidney, can be observed in advanced stages of diabetic nephropathy (DN). Mammalian serine/threonine-protein kinase 4 (MST1), a core component of the Hippo pathway that is involved in cellular proliferation and differentiation, plays a crucial role in the pathogenesis of multiple metabolic diseases, kidney diseases and cancer. METHODS In type 1 and type 2 diabetic animals, as well as in human proximal tubular epithelial cells (HK-2), activation of MST1 was analyzed by immunohistochemistry and western blotting. In db/db mice, MST1 protein was knocked down or overexpressed by shRNA, and renal function, fibrosis, and downstream signaling were then investigated. RNA silencing and overexpression were performed by using an MST1 or YAP knockdown/expression lentivirus to investigate the regulation of MST1-mediated YAP/TEAD signaling pathways in the fibrosis process in HK-2 cells. Luciferase and coimmunoprecipitation (co-IP) assays were used to identify whether YAP directly regulated TEAD activation by forming a YAP-TEAD heterodimer, which ultimately leads to tubulointerstitial fibrosis. RESULTS MST1 activation was significantly decreased in type 1 and type 2 diabetic nephropathy. Notably, the downregulation of MST1 activation was also observed in HK-2 cells in a glucose- and time-dependent manner. In vivo, downregulation of MST1 was sufficient to promote renal dysfunction and fibrosis in db/m mice, whereas overexpression of MST1 ameliorated diabetic nephropathy-induced renal fibrosis. Further mechanistic study demonstrated that activated YAP induced by MST1 inhibition directly upregulated TEAD activation by binding to TEAD and forming a YAP-TEAD heterodimer, resulting in the promotion of epithelial-mesenchymal transition (EMT) and fibrosis in renal tubular epithelial. CONCLUSIONS MST1 activation represents a potential therapeutic strategy to treat or prevent the progression of diabetic nephropathy-induced renal fibrosis.

中文翻译：

---

通过 Yes 相关蛋白/TEA 结构域转录因子介导的上皮间质转化靶向哺乳动物丝氨酸/苏氨酸蛋白激酶 4，可改善糖尿病肾病伴肾纤维化。

基本原理 与肾脏功能损伤密切相关的肾小管间质纤维化可在糖尿病肾病 (DN) 的晚期阶段观察到。哺乳动物丝氨酸/苏氨酸蛋白激酶 4 (MST1) 是 Hippo 通路的核心成分，参与细胞增殖和分化，在多种代谢疾病、肾脏疾病和癌症的发病机制中起关键作用。方法 在 1 型和 2 型糖尿病动物以及人近端肾小管上皮细胞 (HK-2) 中，通过免疫组织化学和蛋白质印迹分析 MST1 的活化。在 db/db 小鼠中，MST1 蛋白被 shRNA 敲低或过表达，然后研究肾功能、纤维化和下游信号传导。通过使用 MST1 或 YAP 敲低/表达慢病毒进行 RNA 沉默和过表达，以研究 MST1 介导的 YAP/TEAD 信号通路在 HK-2 细胞纤维化过程中的调节。荧光素酶和免疫共沉淀 (co-IP) 测定用于确定 YAP 是否通过形成 YAP-TEAD 异二聚体直接调节 TEAD 活化，最终导致肾小管间质纤维化。结果 MST1 激活在 1 型和 2 型糖尿病肾病中显着降低。值得注意的是，在 HK-2 细胞中也观察到 MST1 活化的下调，其呈葡萄糖和时间依赖性。在体内，MST1 的下调足以促进 db/m 小鼠的肾功能障碍和纤维化，而 MST1 的过表达改善了糖尿病肾病诱导的肾纤维化。进一步的机制研究表明，抑制 MST1 诱导的活化 YAP 通过与 TEAD 结合并形成 YAP-TEAD 异二聚体直接上调 TEAD 活化，从而促进上皮间质转化 (EMT) 和肾小管上皮纤维化。结论 MST1 激活代表了治疗或预防糖尿病肾病引起的肾纤维化进展的潜在治疗策略。