HO-1 Protects against Hypoxia/Reoxygenation-Induced Mitochondrial Dysfunction in H9c2 Cardiomyocytes

Abstract

BackgroundMitochondrial dysfunction would ultimately lead to myocardial cell apoptosis and death during ischemia-reperfusion injuries. Autophagy could ameliorate mitochondrial dysfunction by autophagosome forming, which is a catabolic process to preserve the mitochondrial’s structural and functional integrity. HO-1 induction and expression are important protective mechanisms. This study in order to investigate the role of HO-1 during mitochondrial damage and its mechanism.Methods and ResultsThe H9c2 cardiomyocyte cell line were incubated by hypoxic and then reoxygenated for the indicated time (2, 6, 12, 18, and 24 h). Cell viability was tested with CCK-8 kit. The expression of endogenous HO-1(RT-PCR and Western blot) increased with the duration of reoxygenation and reached maximum levels after 2 hours of H/R; thereafter, the expression gradually decreased to a stable level. Mitochondrial dysfunction (Flow cytometry quantified the ROS generation and JC-1 staining) and autophagy (The Confocal microscopy measured the autophagy. RFP-GFP-LC3 double-labeled adenovirus was used for testing.) were induced after 6 hours of H/R. Then, genetic engineering technology was employed to construct an Lv-HO1-H9c2 cell line. When HO-1 was overexpressed, the LC3II levels were significantly increased after reoxygenation, p62 protein expression was significantly decreased, the level of autophagy was unchanged, the mitochondrial membrane potential was significantly increased, and the mitochondrial ROS level was significantly decreased. Furthermore, when the HO-1 inhibitor ZnPP was applied the level of autophagy after reoxygenation was significantly inhibited, and no significant improvement in mitochondrial dysfunction was observed.ConclusionsDuring myocardial hypoxia-reoxygenation injury, HO-1 overexpression induces autophagy to protect the stability of the mitochondrial membrane and reduce the amount of mitochondrial oxidation products, thereby exerting a protective effect.

CLOCK Promotes Endothelial Damage by Inducing Autophagy through Reactive Oxygen Species

“…Previous studies have demonstrated that hypoxia caused injury via regulating autophagy [9, 27]. Consistent with these reports, our findings showed that hypoxia induced autophagy and endothelial dysfunction.…”

“…Moreover, ROS was crucial in hypoxia-induced autophagy [26, 27]. Therefore, we further explored if ROS plays a role in CLOCK-induced cell autophagy and dysfunction in HUVECs.…”

“…Previous studies demonstrated that autophagy was involved in irreversible cellular dysfunction or cell death by various stressors, including ischemia, hypoxia, energy deprivation, and excitotoxic stimuli [10, 27]. By contrast, autophagy was reported to play a protective role in MMP-2-mediated cell transmigration and cell death in high glucose-stimulated HUVECs [28].…”

Passive heat therapy protects against endothelial cell hypoxia‐reoxygenation via effects of elevations in temperature and circulating factors

“…; Chen et al . ). We hypothesized that both heat pretreatment and exposure to heat therapy serum would upregulate HO‐1 and that it would remain elevated following H/R.…”

“…Secondly, we investigated potential mechanisms behind heat therapy-mediated protection against H/R. Haemeoxygenase-1 (HO-1), which is also an HSP (Hsp32), is capable of suppressing NF-κB activation (Chi et al 2014) and has been shown to protect against H/R-induced inflammation (Park et al 2013;Chen et al 2016). We hypothesized that both heat pretreatment and exposure to heat therapy serum would upregulate HO-1 and that it would remain elevated following H/R.…”