School of Biosciences and Technology, Chengdu Medical College, Chengdu, Sichuan, China; Pediatric Research Institute, Department of Pediatrics, University of Louisville School of Medicine, Louisville, KY, USA.
Department of Pediatrics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
Redox Biol. 2022 Oct;56:102449. doi: 10.1016/j.redox.2022.102449. Epub 2022 Aug 28.
Endothelial progenitor cells (EPCs) are reduced in number and impaired in function in diabetic patients. Whether and how Nrf2 regulates the function of diabetic EPCs remains unclear. In this study, we found that the expression of Nrf2 and its downstream genes were decreased in EPCs from both diabetic patients and db/db mice. Survival ability and angiogenic function of EPCs from diabetic patients and db/db mice also were impaired. Gain- and loss-of-function studies, respectively, showed that knockdown of Nrf2 increased apoptosis and impaired tube formation in EPCs from healthy donors and wild-type mice, while Nrf2 overexpression decreased apoptosis and rescued tube formation in EPCs from diabetic patients and db/db mice. Additionally, proangiogenic function of Nrf2-manipulated mouse EPCs was validated in db/db mice with hind limb ischemia. Mechanistic studies demonstrated that diabetes induced mitochondrial fragmentation and dysfunction of EPCs by dysregulating the abundance of proteins controlling mitochondrial dynamics; upregulating Nrf2 expression attenuated diabetes-induced mitochondrial fragmentation and dysfunction and rectified the abundance of proteins controlling mitochondrial dynamics. Further RNA-sequencing analysis demonstrated that Nrf2 specifically upregulated the transcription of isocitrate dehydrogenase 2 (IDH2), a key enzyme regulating tricarboxylic acid cycle and mitochondrial function. Overexpression of IDH2 rectified Nrf2 knockdown- or diabetes-induced mitochondrial fragmentation and EPC dysfunction. In a therapeutic approach, supplementation of an Nrf2 activator sulforaphane enhanced angiogenesis and blood perfusion recovery in db/db mice with hind limb ischemia. Collectively, these findings indicate that Nrf2 is a potential therapeutic target for improving diabetic EPC function. Thus, elevating Nrf2 expression enhances EPC resistance to diabetes-induced oxidative damage and improves therapeutic efficacy of EPCs in treating diabetic limb ischemia likely via transcriptional upregulating IDH2 expression and improving mitochondrial function of diabetic EPCs.
内皮祖细胞 (EPCs) 在糖尿病患者中的数量减少且功能受损。Nrf2 是否以及如何调节糖尿病 EPC 的功能尚不清楚。在这项研究中，我们发现糖尿病患者和 db/db 小鼠的 EPC 中 Nrf2 及其下游基因的表达减少。糖尿病患者和 db/db 小鼠的 EPC 的生存能力和血管生成功能也受损。分别进行的增益和失能研究表明，Nrf2 敲低增加了来自健康供体和野生型小鼠的 EPC 的细胞凋亡并损害了其管状形成能力，而 Nrf2 过表达则减少了糖尿病患者和 db/db 小鼠的 EPC 的细胞凋亡并挽救了其管状形成能力。此外，在患有下肢缺血的 db/db 小鼠中验证了 Nrf2 操纵的小鼠 EPC 的促血管生成功能。机制研究表明，糖尿病通过失调控制线粒体动力学的蛋白质的丰度诱导 EPC 中线粒体片段化和功能障碍；上调 Nrf2 表达减弱了糖尿病诱导的线粒体片段化和功能障碍，并纠正了控制线粒体动力学的蛋白质的丰度。进一步的 RNA 测序分析表明，Nrf2 特异性地上调了调节三羧酸循环和线粒体功能的关键酶异柠檬酸脱氢酶 2 (IDH2) 的转录。IDH2 的过表达纠正了 Nrf2 敲低或糖尿病诱导的线粒体片段化和 EPC 功能障碍。在治疗方法中，补充 Nrf2 激活剂萝卜硫素增强了 db/db 小鼠下肢缺血后血管生成和血液灌注的恢复。总之，这些发现表明 Nrf2 是改善糖尿病 EPC 功能的潜在治疗靶点。因此，提高 Nrf2 表达可增强 EPC 对糖尿病诱导的氧化损伤的抵抗力，并通过转录上调 IDH2 表达和改善糖尿病 EPC 的线粒体功能来提高 EPC 治疗糖尿病肢体缺血的治疗效果。
