SIRT2（沉默交配型信息调节 2 同源物-2）对 Septin4 的去乙酰化作用减轻了高血压肾病的损害。

BACKGROUND: Hypertension can lead to podocyte damage and subsequent apoptosis, eventually resulting in glomerulosclerosis. Although alleviating podocyte apoptosis has clinical significance for the treatment of hypertensive nephropathy, an effective therapeutic target has not yet been identified. The function of septin4, a proapoptotic protein and an important marker of organ damage, is regulated by post-translational modification. However, the exact role of septin4 in regulating podocyte apoptosis and its connection to hypertensive renal damage remains unclear. METHODS: We investigated the function and mechanism of septin4 in hypertensive nephropathy to discover a theoretical basis for targeted treatment. Mouse models including Rosa 26 (Gt(ROSA)26Sor)- (silent mating type information regulation 2 homolog-2)-Flag-TG (transgenic) (-TG) mice -knockout, and -K174Q mutant mice, combined with proteomic and acetyl proteomics analysis, followed by multiple molecular biological methodologies, were used to demonstrate mechanisms of SIRT2-mediated deacetylation of septin4-K174 in hypertensive nephropathy. RESULTS: Using transgenic -K174Q mutant mice treated with the antioxidant Tempol, we found that hyperacetylation of the K174 site of septin4 exacerbates Ang II (angiotensin II)- induced hypertensive renal injury resulting from oxidative stress. Proteomics and Western blotting assays indicated that septin4-K174Q activates the cleaved-PARP1 (poly [ADP-ribose] polymerase family, member 1)-cleaved-caspase3 pathway. In septin4-knockdown human renal podocytes, septin4-K174R, which mimics deacetylation at K174, rescues podocyte apoptosis induced by Ang II. Immunoprecipitation and mass spectrometry analyses identified SIRT2 as a deacetylase that interacts with the septin4 GTPase domain and deacetylates septin4-K174. In -deficient mice and SIRT2-knockdown renal podocytes, septin4-K174 remains hyperacetylated and exacerbates hypertensive renal injury. By contrast, in Rosa26-Sirt2-Flag (SIRT2-TG) mice and SIRT2-knockdown renal podocytes reexpressing wild-type SIRT2, septin4-K174 is hypoacetylated and mitigates hypertensive renal injury. CONCLUSIONS: Septin4, when activated through acetylation of K174 (K174Q), promotes hypertensive renal injury. Septin4-K174R, which mimics deacetylation by SIRT2, inhibits the cleaved-PARP1-cleaved-caspase3 pathway. Septin4-K174R acts as a renal protective factor, mitigating Ang II-induced hypertensive renal injury. These findings indicate that septin4-K174 is a potential therapeutic target for the treatment of hypertensive renal injury.

背景：高血压可导致足细胞损伤和随后的细胞凋亡，最终导致肾小球硬化。尽管缓解足细胞凋亡对治疗高血压肾病具有临床意义，但尚未确定有效的治疗靶点。作为一种促凋亡蛋白和重要的器官损伤标志物，桩蛋白 4 的功能受翻译后修饰调节。然而，桩蛋白 4 调节足细胞凋亡的确切作用及其与高血压肾损伤的关系尚不清楚。

方法：我们研究了桩蛋白 4 在高血压肾病中的功能和机制，以发现靶向治疗的理论基础。使用包括 Rosa 26（Gt(ROSA)26Sor)-沉默交配型信息调节 2 同源物-2-Flag-TG（转基因）(-TG) 敲除小鼠和 -K174Q 突变小鼠在内的小鼠模型，结合蛋白质组学和乙酰化蛋白质组学分析，以及多种分子生物学方法，证明了 SIRT2 介导的桩蛋白 4-K174 去乙酰化在高血压肾病中的机制。

结果：使用抗氧化剂 Tempol 处理的转基因 -K174Q 突变小鼠，我们发现桩蛋白 4-K174 位点的过度乙酰化加剧了 Ang II（血管紧张素 II）诱导的高血压肾损伤，这是由氧化应激引起的。蛋白质组学和 Western blot 检测表明，桩蛋白 4-K174Q 激活了 cleaved-PARP1（多聚[ADP-核糖]聚合酶家族，成员 1）-cleaved-caspase3 途径。在桩蛋白 4 敲低的人肾足细胞中，模拟 K174 去乙酰化的桩蛋白 4-K174R 挽救了 Ang II 诱导的足细胞凋亡。免疫沉淀和质谱分析鉴定 SIRT2 为与桩蛋白 4 GTP 结构域相互作用并去乙酰化桩蛋白 4-K174 的去乙酰化酶。在 -/- 小鼠和 SIRT2 敲低的肾足细胞中，桩蛋白 4-K174 仍然过度乙酰化，加剧了高血压肾损伤。相比之下，在 Rosa26-Sirt2-Flag（SIRT2-TG）小鼠和表达野生型 SIRT2 的 SIRT2 敲低肾足细胞中，桩蛋白 4-K174 被低乙酰化并减轻了高血压肾损伤。

结论：激活的桩蛋白 4 通过 K174（K174Q）乙酰化促进高血压肾损伤。模拟 SIRT2 去乙酰化的桩蛋白 4-K174R 抑制 cleaved-PARP1-cleaved-caspase3 途径。桩蛋白 4-K174R 作为一种肾保护因子，减轻 Ang II 诱导的高血压肾损伤。这些发现表明，桩蛋白 4-K174 是治疗高血压肾损伤的潜在治疗靶点。