Department of Neurosurgery, Hunan University of Medicine General Hospital, 418000 Huaihua, Hunan, China.
School of Public Health and Laboratory Medicine, Hunan University of Medicine, 418000 Huaihua, Hunan, China.
Discov Med. 2024 May;36(184):1020-1029. doi: 10.24976/Discov.Med.202436184.95.
Long-term exposure to cadmium can induce renal toxicity in rats, leading to endoplasmic reticulum (ER) stress and iron death. Notably, in cadmium-exposed rats, there is an increased expression of UNC93B1 (unc-93 homolog B1). Consequently, our investigation aims to determine the impact of UNC93B1 on ER stress and iron death in cadmium-exposed rats by modulating the cGAS-STING (cyclic GMP-AMP synthase-stimulator of interferon genes) pathway.
A cadmium-exposed rat model was established by intrabacally injecting chromium chloride (5 mg/kg, once a day for 4 weeks), and the levels of UCd (urine cadmium), UNAG (urine -acetyl-β-D-glucosaminidase), and UCr (urine creatinine) in urine were assessed. A silent UNC93B1 lentivirus was constructed, and STING agonists were procured and administered to the rats. Subsequently, kidney tissues were extracted post-mortem, and pathological changes in renal tissue were observed through hematoxylin and eosin (HE) staining. The expression and mRNA levels of UNC93B1, cGAS, and STING were examined using western blot (WB) and polymerase chain reaction (PCR). Autophagy proteins (light chain 3 (LC3), Beclin-1, p62) were also assessed by WB. Additionally, iron concentration was determined using a kit, while oxidative stress markers (cytochrome oxidase subunit 2 (COX2), glutathione peroxidase 4 (GPX4), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH)) were measured through enzyme-linked immunosorbent assay (ELISA). Furthermore, endoplasmic reticulum stress proteins (protein kinase RNA-like ER kinase (PERK), CCAAT enhance-binding protein homologous protein (CHOP), activating transcription factor-4 (ATF4)) were analyzed by WB.
Wstaining, WB, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), ELISA, and HE staining collectively revealed a heightened expression of UNC93B1, cGAS, and STING, accompanied by increased levels of autophagy, oxidative stress, and ER stress in cadmium-exposed rats ( < 0.05). Nephrotoxicity exhibited a reduction following the inhibition of UNC93B1, leading to decreased levels of oxidative stress, autophagy, and ER stress ( < 0.05). Notably, this observed phenomenon was reversed upon the addition of STING agonists, suggesting that UNC93B1 might exert a nephroprotective effect in cadmium-exposed rats through modulation of the cGAS-STING pathway.
The inhibition of UNC93B1 mitigates nephrotoxicity in cadmium-exposed rats, and this protective effect is mechanistically linked to the cGAS-STING pathway.
长期接触镉会导致大鼠肾毒性，引发内质网（ER）应激和铁死亡。值得注意的是，在镉暴露的大鼠中，UNC93B1（unc-93 同源物 B1）的表达增加。因此，我们的研究旨在通过调节 cGAS-STING（环鸟苷酸-AMP 合酶-干扰素基因刺激物）途径来确定 UNC93B1 对镉暴露大鼠 ER 应激和铁死亡的影响。
通过经口注射氯化铬（5mg/kg，每天一次，持续 4 周）建立镉暴露大鼠模型，检测尿液中 UCd（尿镉）、UNAG（尿 -乙酰-β-D-氨基葡萄糖苷酶）和 UCr（尿肌酐）的水平。构建沉默 UNC93B1 慢病毒，并获取 STING 激动剂并给予大鼠。然后，提取大鼠死后的肾组织，通过苏木精和伊红（HE）染色观察肾组织的病理变化。采用 Western blot（WB）和聚合酶链反应（PCR）检测 UNC93B1、cGAS 和 STING 的表达和 mRNA 水平。通过 WB 还评估自噬蛋白（微管相关蛋白轻链 3（LC3）、Beclin-1、p62）。此外，使用试剂盒测定铁浓度，通过酶联免疫吸附试验（ELISA）测定氧化应激标志物（细胞色素氧化酶亚基 2（COX2）、谷胱甘肽过氧化物酶 4（GPX4）、超氧化物歧化酶（SOD）、丙二醛（MDA）、谷胱甘肽（GSH））。此外，通过 WB 分析内质网应激蛋白（蛋白激酶 RNA 样内质网激酶（PERK）、CCAAT 增强子结合蛋白同源蛋白（CHOP）、激活转录因子 4（ATF4））。
Wstaining、WB、逆转录定量聚合酶链反应（RT-qPCR）、ELISA 和 HE 染色共同显示 UNC93B1、cGAS 和 STING 的表达增加，同时镉暴露大鼠的自噬、氧化应激和 ER 应激水平升高（<0.05）。抑制 UNC93B1 后肾毒性降低，氧化应激、自噬和 ER 应激水平降低（<0.05）。值得注意的是，加入 STING 激动剂后观察到这种现象逆转，表明 UNC93B1 可能通过调节 cGAS-STING 途径在镉暴露大鼠中发挥肾保护作用。
抑制 UNC93B1 减轻镉暴露大鼠的肾毒性，这种保护作用与 cGAS-STING 途径有关。
