The First Affiliated Hospital of Hainan Medical University, No. 31 Longhua Road, Haikou, 570102, Hannan, China.
Department of Neurology and Neuroscience, Okayama University School of Medicine, Okayama, 700-8558, Japan.
J Neuroinflammation. 2022 Sep 1;19(1):213. doi: 10.1186/s12974-022-02542-7.
Chronic kidney disease (CKD), characterized as renal dysfunction, is regarded as a major public health problem which carries a high risk of cardiovascular diseases. The purpose of this study is to evaluate the functional significance of Drp1 in hypercalcemia-associated neuronal damage following CKD and the associated mechanism.
Initially, the CKD mouse models were established. Next, RT-qPCR and Western blot analysis were performed to measure expression of Fis1 and Drp1 in CKD. Chromatin immunoprecipitation (ChIP) assay and dual-luciferase reporter gene assay were utilized to explore the relationship among Drp1, HIF-1α, EZH2, and ROS with primary cortical neurons isolated from neonatal mice. Next, CKD mice were subjected to calcitonin treatment or manipulation with adenovirus expressing sh-Drp1, so as to explore the effects of Drp1 on hypercalcemia-induced neuronal injury in CKD. TUNEL assay and immunofluorescence staining were performed to detect apoptosis and NeuN-positive cells (neurons) in prefrontal cortical tissues of CKD mice.
It was found that hypercalcemia could induce neuronal injury in CKD mice. An increase of Fis1 and Drp1 expression in cerebral cortex of CKD mice correlated with mitochondrial fragmentation. Calcitonin suppressed Drp1/Fis1-mediated mitochondrial fragmentation to attenuate hypercalcemia-induced neuronal injury after CKD. Additionally, Drp1 could increase EZH2 expression through the binding of HIF-1α to EZH2 promoter via elevating ROS generation. Furthermore, Drp1 knockdown inhibited hypercalcemia-induced neuronal injury in CKD while overexpression of EZH2 could reverse this effect in vivo.
Taken together, the key findings of the current study demonstrate the promotive role of Drp1 in mitochondrial fragmentation which contributes to hypercalcemia-induced neuronal injury in CKD.
慢性肾脏病（CKD）表现为肾功能障碍，被认为是一个主要的公共卫生问题，其心血管疾病风险很高。本研究旨在评估 Drp1 在 CKD 后高钙血症相关神经元损伤中的功能意义及其相关机制。
首先建立 CKD 小鼠模型。然后，通过 RT-qPCR 和 Western blot 分析测量 CKD 中 Fis1 和 Drp1 的表达。利用染色质免疫沉淀（ChIP）测定和双荧光素酶报告基因测定来探索 Drp1、HIF-1α、EZH2 和 ROS 与从新生小鼠分离的原代皮质神经元之间的关系。然后，用降钙素处理 CKD 小鼠或用表达 sh-Drp1 的腺病毒处理，以探讨 Drp1 对 CKD 中高钙血症诱导的神经元损伤的影响。用 TUNEL 测定和免疫荧光染色来检测 CKD 小鼠前额皮质组织中的细胞凋亡和 NeuN 阳性细胞（神经元）。
发现高钙血症可诱导 CKD 小鼠神经元损伤。CKD 小鼠大脑皮质中 Fis1 和 Drp1 表达增加与线粒体碎片化相关。降钙素通过抑制 Drp1/Fis1 介导的线粒体碎片化来抑制 CKD 后高钙血症诱导的神经元损伤。此外，Drp1 可通过增加 ROS 生成来增加 HIF-1α 与 EZH2 启动子的结合，从而增加 EZH2 的表达。此外，Drp1 敲低可抑制 CKD 中高钙血症诱导的神经元损伤，而过表达 EZH2 可在体内逆转这种作用。
综上所述，本研究的主要发现表明，Drp1 在促进线粒体碎片化方面发挥了作用，这有助于 CKD 中高钙血症诱导的神经元损伤。
