[Effect of total secondary ginsenosides on apoptosis and energy metabolism of H9c2 cells under hypoxia based on mitochondrial biogenesis].

Abstract

This study explores the effect of total secondary ginsenosides(TSG) on apoptosis and energy metabolism in H9c2 cells under hypoxia and its potential mechanisms. H9c2 cell viability was observed and the apoptosis rate was calculated to determine suitable intervention concentrations of TSG, antimycin A complex(AMA), and coenzyme Q10(CoQ10), along with the duration of hypoxia. H9c2 cells at the logarithmic phase were divided into a normal group, a model group, a TSG group, an AMA group, a TSG+AMA group, and a CoQ10 group. All groups, except the normal group, were treated with their respective intervention drugs and cultured under hypoxic conditions. Adenosine triphosphate(ATP) content and creatine kinase(CK) activity were measured using an ATP chemiluminescence assay kit and a CK colorimetric assay kit. Flow cytometry was used to assess apoptosis rates, and Western blot evaluated the expression levels of apoptosis-related proteins, including B-cell lymphoma 2(Bcl-2), Bcl-2-associated X protein(Bax), cysteinyl aspartate-specific protease(caspase)-3, caspase-8, and caspase-9, as well as mitochondrial biogenesis-related proteins peroxisome proliferator-activated receptor-γ coactivator 1α(PGC-1α), estrogen-related receptor-α(ERRα), nuclear respiratory factor(NRF)-1, NRF-2, peroxisome proliferator activated receptor-α(PPARα), and Na~+-K~+-ATPase. RT-PCR was employed to analyze the mRNA expression of mitochondrial biogenesis factors, including PGC-1α, ERRα, NRF-1, NRF-2, PPARα, mitochondrial transcription factor A(TFAM), mitochondrial cytochrome C oxidase 1(COX1), and mitochondrial NADH dehydrogenase subunit 1(ND1), ND2. The selected intervention concentrations were 7.5 μg·mL~(-1) for TSG, 10 μmol·L~(-1) for AMA, and 1×10~(-4) mol·L~(-1) for CoQ10, with a hypoxia duration of 6 h. Compared with the normal group, the model group showed decreased ATP content and CK activity, increased apoptosis rates, decreased Bcl-2 expression, and increased Bax, caspase-3, caspase-8, and caspase-9 expression in H9c2 cells. Additionally, the protein and mRNA expression levels of mitochondrial biogenesis-related factors(PGC-1α, ERRα, NRF-1, NRF-2, PPARα), mRNA expression of TFAM, COX1, and ND1, ND2, and protein expression of Na~+-K~+-ATPase in mitochondrial DNA, were also reduced. In the TSG and CoQ10 groups, ATP content and CK activity increased, and apoptosis rates decreased compared with those in the model group. The TSG group showed decreased protein expression of apoptosis-related proteins Bax, caspase-3, caspase-8, and caspase-9, increased protein and mRNA expression of mitochondrial biogenesis factors PGC-1α, ERRα, NRF-1, and PPARα, and increased NRF-2 protein expression and TFAM mRNA expression in mitochondrial DNA. Conversely, in the AMA group, ATP content and CK activity decreased, the apoptosis rate increased, Bcl-2 expression decreased, and Bax, caspase-3, caspase-8, and caspase-9 expression increased, alongside reductions in PGC-1α, ERRα, NRF-1, NRF-2, PPARα protein and mRNA expression, as well as TFAM, COX1, ND1, ND2 mRNA expression and Na~+-K~+-ATPase protein expression. Compared with the TSG group, the TSG+AMA group exhibited decreased ATP content and CK activity, increased apoptosis rates, decreased Bcl-2 expression, and increased Bax, caspase-3, caspase-8, and caspase-9 expression, along with decreased PGC-1α, ERRα, NRF-1, NRF-2, and PPARα protein and mRNA expression and TFAM, COX1, and ND1, ND2 mRNA expression. Compared with the AMA group, the TSG+AMA group showed increased CK activity, decreased apoptosis rate, increased Bcl-2 expression, and decreased Bax, caspase-8, and caspase-9 expression. Additionally, the protein and mRNA expression of PGC-1α, ERRα, NRF-1, PPARα, mRNA expression of TFAM, COX1, ND1, ND2, and Na~+-K~+-ATPase protein expression increased. In conclusion, TSG enhance ATP content and CK activity and inhibit apoptosis in H9c2 cells under hypoxia, and the mechanisms may be related to the regulation of PGC-1α, ERRα, NRF-1, NRF-2, PPARα, and TFAM expression, thus promoting mitochondrial biogenesis.