Effect of Linggui Zhugan Decoction-containing serum on mitochondrial oxidative stress in cardiomyocytes: an exploration based on Nrf2/BNIP3 signaling pathway

Abstract

This study aimed to explore the effect of Linggui Zhugan Decoction(LGZGD)-containing serum on mitochondrial oxidative stress in cardiomyocytes based on the NF-E2-related factor2(Nrf2)/Bcl-2/adenovirus E1 B 19 kDa interacting protein(BNIP3) signaling pathway. After the preparation of LGZGD-containing serum and blank serum, H9 c2 cardiomyocytes were exposed to H_2O_2 for inducing oxidative stress in vitro. The H9 c2 cells were divided into four groups, namely normal control group, H_2O_2 model group, 20% blank serum group, and 20% LGZGD-containing serum group. After the cells were pre-treated with different types of serum for 12 h and cultured with 100 μmol·L~(-1 )H_2O_2 for 6 h, the reactive oxygen species(ROS) level in each group was detected by DCFH-DA, and the openness of mitochondrial permeability transition pore(mPTP) was measured using a calcein AM fluorescent probe. The expression levels of cytoplasmic cytochrome C(CytC), mitochondrial CytC, cytoplasmic and nuclear Nrf2, and BNIP3 were detected by Western blot. Nrf2-silenced H9 c2 cells were prepared by transfecting them with siRNA-Nrf2 for investigating the efficacy of LGZGD-containing serum in regulating ROS, mPTP, cytoplasmic and mitochondrial CytC, and BNIP3. The results showed that compared with the normal control group, H_2O_2 significantly increased the ROS content and mPTP openness(P<0.01), and the expression of Nrf2, BNIP3, and cytoplasmic CytC(P<0.01), and decreased the expression of mitochondrial CytC(P<0.01), without causing obvious change in cytoplasmic Nrf2. LGZGD-containing serum significantly lowered ROS content(P<0.01), inhibited mPTP openness(P<0.01), down-regulated the expression of cytoplasmic CytC and BNIP3(P<0.01), up-regulated mitochondrial CytC expression(P<0.01), and promoted Nrf2 nuclear translocation(P<0.05). However, after Nrf2 silencing, the reduced ROS production, diminished BNIP3 expression, and inhibited mPTP openness and CytC release induced by LGZGD-containing serum were reversed(P<0.01). These results have suggested that LGZGD-containing serum is able to alleviate the mitochondrial oxidative stress injury of cardiomyocytes by regulating the Nrf2/BNIP3 signaling pathway.