Hebei University of Chinese Medicine, Shijiazhuang 050091, China.
Hebei University of Chinese Medicine, Shijiazhuang 050091, China; Hebei Key Laboratory of Integrative Medicine on Liver-kidney Patterns, Shijiazhuang 050091, China; Institute of Integrative Medicine, College of Integrative Medicine, Hebei University of Chinese Medicine, Shijiazhuang 050200, China.
Biochim Biophys Acta Mol Cell Res. 2024 Oct;1871(7):119813. doi: 10.1016/j.bbamcr.2024.119813. Epub 2024 Aug 12.
Angiogenesis is closely related to renal fibrosis; however, its basic mechanism remains unclear. In our study, we found that nuclear receptor 4A1 (NR4A1) inhibits vascular endothelial growth factor A (VEGFA)-induced angiogenesis, ameliorating renal fibrosis.
We prepared a renal fibrosis animal model with unilateral ureteral obstruction (UUO) and NR4A1 knockdown UUO mice model, Using Human umbilical vein endothelial cells (HUVECs) to conduct all in vitro experiments. We then detected and analyzed the expression levels of NR4A1 and other genes related to angiogenesis and fibrosis.
The angiogenesis related genes, such as VEGFA, vascular endothelial growth factor receptor-2 (VEGFR-2), endoglin (CD105), as well as the expression of fibrosis related genes that included, α-smooth muscle actin (α-SMA), Vimentin, and Collagen I are all significantly increased in the UUO rat model. In addition, the expression of NR4A1 of the kidney tissue of UUO rats was significantly reduced. Therefore, according to the above results, we speculated that angiogenesis may exacerbate renal fibrosis and NR4A1 may repress renal fibrosis by inhibiting angiogenesis. To further verify the above results, we used VEGFA to stimulate HUVECs with (or without) overexpression or knockdown of NR4A1. The results showed that with prolonged stimulation using VEGFA, the expression of NR4A1 decreases. Overexpression of NR4A1 significantly inhibits the expression of related indicators of angiogenesis and renal fibrosis. Furthermore, knockdown of NR4A1 induces endothelial cell proliferation and migration; therefore, exacerbating angiogenesis and fibrosis. Finally, the results of NR4A1 knockdown UUO mice showed that knockdown of NR4A1 can aggravating kidney damage and induce the expression of angiogenesis and renal fibrosis related indicators, while UUO can significantly induce kidney damage, angiogenesis and renal fibrosis. When knockdown of NR4A1, renal kidney damage, angiogenesis and fibrosis becomes more severe than UUO. Thus, all of these results indicate that NR4A1 can ameliorate renal fibrosis by inhibiting angiogenesis.
NR4A1 can inhibit angiogenesis to ameliorate renal fibrosis.
血管生成与肾纤维化密切相关，但基本机制尚不清楚。在本研究中，我们发现核受体 4A1（NR4A1）抑制血管内皮生长因子 A（VEGFA）诱导的血管生成，从而改善肾纤维化。
我们通过单侧输尿管梗阻（UUO）制备了肾纤维化动物模型和 NR4A1 敲低 UUO 小鼠模型，使用人脐静脉内皮细胞（HUVECs）进行所有体外实验。然后，我们检测和分析了 NR4A1 及其他与血管生成和纤维化相关基因的表达水平。
UUO 大鼠模型中血管生成相关基因（如 VEGFA、血管内皮生长因子受体 2（VEGFR-2）、内胚层（CD105））以及纤维化相关基因（如α-平滑肌肌动蛋白（α-SMA）、波形蛋白和胶原 I）的表达均显著增加。此外，UUO 大鼠肾组织中 NR4A1 的表达明显降低。因此，根据上述结果，我们推测血管生成可能加重肾纤维化，NR4A1 通过抑制血管生成来抑制肾纤维化。为了进一步验证上述结果，我们使用 VEGFA 刺激过表达或敲低 NR4A1 的 HUVECs。结果表明，随着 VEGFA 刺激时间的延长，NR4A1 的表达减少。过表达 NR4A1 可显著抑制血管生成和肾纤维化相关指标的表达。此外，敲低 NR4A1 可诱导内皮细胞增殖和迁移，从而加剧血管生成和纤维化。最后，NR4A1 敲低 UUO 小鼠的结果表明，敲低 NR4A1 可加重肾脏损伤并诱导血管生成和肾纤维化相关指标的表达，而 UUO 可显著诱导肾脏损伤、血管生成和肾纤维化。当敲低 NR4A1 时，肾脏损伤、血管生成和纤维化比 UUO 更严重。因此，所有这些结果表明 NR4A1 通过抑制血管生成来改善肾纤维化。
NR4A1 可通过抑制血管生成来改善肾纤维化。
