Ginsenoside Rg1 protects against ischemic/reperfusion‐induced neurotoxicity through miR‐144/Nrf2/ARE pathway
Authors: Chen Naihong , Chu Shifeng , Zhou Xin , Chen Chen , Zhang Zhao 
Published: June 2021

AimGinsenoside Rg1 (Rg1), a purified compound from Panax ginseng, has been well documented to be effective against ischemia/reperfusion (I/R) neurotoxicity. However, the underlying mechanism is still obscure.MethodsThe anti‐I/R effect of Rg1 were investigated in vitro and in vivo, and the dynamics of nuclear accumulation and the transcriptional activity of Nrf2 determined by western blot and Dual Luciferase Reporter Assay, respectively. Nrf2 siRNA was employed to investigate Nrf2's role in the protective effect of Rg1 against I/R. Furthermore, the role of miR‐144, which could regulate post‐translational Nrf2 levels, was investigated in the anti‐I/R effect of Rg1 by injection of AAV‐hypoxia‐inducible factor miR‐144‐shRNA in the predicted ischemic penumbra.ResultsIt was found that the anti‐I/R effect of Rg1 is related to its anti‐oxidative capacity, which is mainly regulated by the Nrf2/ARE pathway. Further study suggested that Rg1 contributes to the enhancement of the Nrf2/ARE pathway, as manifested by increasing the dynamic peak content of Nrf2, which prolonged the maintenance stage, and promoting the expression of ARE‐target genes after oxygen glucose deprivation/reperfusion (OGD/R) in PC12 cells. Nrf2‐siRNA application significantly reduced these changes. Furthermore, the enhancement of the Nrf2/ARE pathway by Rg1 was independent of disassociation from Keap1; rather it was a result of post‐translational regulations. It was found that Rg1 significantly reduced the expression of miR‐144, which down‐regulates Nrf2 production by targeting its 3′‐untranslated region, after OGD/R. Knockdown of Nrf2 showed no effect on the expression of miR‐144, indicating that miR‐144 is an upstream regulator of Nrf2. Moreover, direct binding between Nrf2 and miR‐144 in the PC12 cells was identified. Application of anti‐miR‐144 significantly reduced Rg1's anti‐OGD/R capacity. Finally, the role of miR‐144 in Rg1's anti‐I/R effect was tested by inhibiting miR‐144 in the predicted ischemic penumbra when hypoxia‐inducible‐factor was activated. The results showed that loss of miR‐144 abolished the anti‐I/R effect of Rg1, which included reduced infarct volume, improved neurological scores, attenuated oxidative impairment, as well as activation of the Nrf2/ARE pathway.ConclusionsThese findings demonstrated that oxidative stress after I/R was alleviated by Rg1 through inhibition of miR‐144 activity and subsequent promotion of the Nrf2/ARE pathway at the post‐translational level.Support or Funding InformationThis work was supported by the National Natural Science Foundation of China (81603315, 81730096, 81603316, 81503275, 81730093, 81873026, U1402221), the CAMS Innovation Fund for Medical Sciences (CIFMS) (2016‐I2M‐1‐004), the State Key Laboratory Fund Open Project (GTZK201610), the China Postdoctoral Science Foundation (2013M540066), the PUMC Graduate Education and Teaching Reform Project (10023201600801), the Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study (BZ0150), the opening Program of Shanxi Key Laboratory of Chinese Medicine Encephalopathy (CME‐OP‐2017001), and the Hunan Chinese Herbal Medicine and standardization functions Engineering Research Center (BG201701).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.