复旦大学牛建英小组的研究显示，PU.1/Spi1通过上调Gata2和促进成纤维细胞活化，加重缺血再灌注诱导的急性肾损伤。相关论文于2025年4月1日发表于国际顶尖学术期刊《中国药理学报》杂志上。

在这项研究中，该研究组研究了PU.1/Spi1是否以及如何调节AKI期间肾成纤维细胞的激活。通过夹持双侧肾动脉30min，建立雄性小鼠AKI模型。手术后48小时处死小鼠，采集血液和肾脏样本。课题组发现PU.1/Spi1在缺血/再灌注（I/R）诱导的AKI中表达水平显著上调，并且PU.1/Spi1特异性定位于成纤维细胞。同时，研究团队观察到成纤维细胞的大量激活发生在AKI的早期。PU.1/Spi1敲除显著减弱成纤维细胞的激活，同时炎症因子的释放和小管损伤减少。生物信息学分析显示GATA结合蛋白2 （Gata2）可能是PU.1/Spi1的下游靶基因，是一个进化保守的基因。缺氧/再氧化（H/R）培养的原代无主题肾成纤维细胞中，PU.1/Spi1、Gata2和α-SMA的表达水平显著上调。活化的成纤维细胞表现出增殖能力升高，增殖细胞核抗原（PCNA）和细胞周期蛋白（如cyclin B1和cyclin D3）的上调证明了这一点。活化成纤维细胞中炎性因子的分泌增加。H/R处理成纤维细胞的条件培养基诱导小管细胞损伤并增加凋亡。

通过染色质免疫沉淀和启动子荧光素酶测定，小组证明PU.1/Spi1能够结合到Gata2的启动子区域并增强其转录。他们的研究结果表明，间质成纤维细胞在I/R诱导的AKI早期被激活，并参与肾损伤。上调PU.1/Spi1通过上调其下游基因Gata2刺激成纤维细胞活化。抑制成纤维细胞的活化可能对AKI有有益的作用。

据介绍，以往关于急性肾损伤（AKI）的研究主要集中在肾小管细胞上，而成纤维细胞的具体作用在很大程度上被忽视。最近的证据表明，转录因子PU.1/Spi1是成纤维细胞激活的重要调节剂，而PU.1/Spi1的药理学和遗传沉默会破坏纤维化网络，并将活化的成纤维细胞重新编程为静止的成纤维细胞。

附：英文原文

Title: PU.1/Spi1 exacerbates ischemia-reperfusion induced acute kidney injury via upregulating Gata2 and promoting fibroblast activation

Author: Zong, Chen, Xu, Guo-li, Ning, Ming, Li, Jing-yao, Wang, Xin, Guo, Heng-jiang, Zhang, Li-hong, Zhou, Li, Xu, Chen, Yang, Zhen-hao, Lu, Li-min, Niu, Jian-ying

Issue&Volume: 2025-04-01

Abstract: Previous studies on acute kidney injury (AKI) have predominantly focused on renal tubular cells, while the specific role of fibroblasts has been largely neglected. Recent evidence shows that PU.1/Spi1, a transcription factor, is an important modulator of fibroblast activation, whereas pharmacological and genetic silencing of PU.1/Spi1 disrupts the fibrotic network and reprograms activated fibroblasts into quiescent fibroblasts. In this study we investigated whether and how PU.1/Spi1 regulated renal fibroblast activation during AKI. An AKI model was established in male mice by clamping bilateral renal arteries for 30min. Mice were sacrificed and blood and kidney samples were collected 48h after the surgery. We showed that the expression level of PU.1/Spi1 was significantly upregulated in ischemia/reperfusion (I/R)-induced AKI and PU.1/Spi1 was specifically localized in fibroblasts. Meanwhile, we observed that a massive activation of fibroblasts occurred at the early stage of AKI. PU.1/Spi1 knockout significantly attenuated the activation of fibroblasts along with the decreased release of inflammatory factors and tubular injury. Bioinformatic analysis revealed that GATA binding protein 2 (Gata2), an evolutionarily conserved gene, might be a downstream target gene of PU.1/Spi1. In primary cultured mouse kidney fibroblasts subjected to hypoxia/reoxygenation (H/R), the expression levels of PU.1/Spi1, Gata2 and α-SMA were significantly upregulated. Activated fibroblasts exhibited elevated proliferative capacity, evidenced by upregulated proliferating cell nuclear antigen (PCNA) and cell cycle proteins such as cyclin B1 and cyclin D3. The secretion of inflammatory factors was increased in the activated fibroblasts. Conditioned medium from H/R-treated fibroblasts induced tubular cell injury and increased apoptosis. Using chromatin immunoprecipitation and promoter-luciferase assays, we demonstrated that PU.1/Spi1 was able to bind to the promoter region of Gata2 and enhanced its transcription. Our results show that interstitial fibroblasts are activated at the early stage of I/R-induced AKI and involved in renal injury. Upregulated PU.1/Spi1 stimulates fibroblast activation by upregulating its downstream gene Gata2. Inhibiting the activation of fibroblasts may have a beneficial effect on AKI.

DOI: 10.1038/s41401-025-01530-w

Source: https://www.nature.com/articles/s41401-025-01530-w