Hydrogen Sulfide Attenuates Myocardial Hypoxia-Reoxygenation Injury by Inhibiting Autophagy via mTOR Activation

Background/Aims: Acute myocardial infarction (AMI) occurs when blood supply to the heart is diminished (ischemia) for long time; ischemia is primarily caused due to hypoxia. The present study evaluated the effects of long non-coding RNA H19 on hypoxic rat H9c2 cells and mouse HL-1 cells. Methods: Hypoxic injury was confirmed by measuring cell viability, migration and invasion, and apoptosis using MTT, Transwell and flow cytometry assays, respectively. H19 expression after hypoxia was estimated by qRT-PCR. We then measured the effects of non-physiologically expressed H19, knockdown of miR-139 with or without H19 silence, and abnormally expressed Sox8 on hypoxia-induced H9c2 cells. Moreover, the interacted miRNA for H19 and downstream target gene were virtually screened and verified. The involved signaling pathways and the effects of abnormally expressed H19 on contractility of HL-1 cells were explored via Western blot analysis. Results: Hypoxia induced decreases of cell viability, migration and invasion, increase of cell apoptosis and up-regulation of H19. Knockdown of H19 increased hypoxia-induced injury in H9c2 cells. H19 acted as a sponge for miR-139 and H19 knockdown aggravated hypoxia-induced injury by up-regulating miR-139. Sox8 was identified as a target of miR-139, and its expression was negatively regulated by miR-139. The mechanistic studies revealed that overexpression of Sox8 might decrease hypoxia-induced cell injury by activating the PI3K/AKT/mTOR pathway and MAPK. Besides, H19 promoted contractility of HL-1 cells. Conclusion: These findings suggest that H19 alleviates hypoxia-induced myocardial cell injury by miR-139-mediated up-regulation of Sox8, along with activation of the PI3K/AKT/mTOR pathway and MAPK.

Section: Discussionmentioning

confidence: 99%

Long Non-Coding RNA H19 Protects H9c2 Cells against Hypoxia-Induced Injury by Targeting MicroRNA-139

Gong¹,

Xu²,

Guo³

et al. 2017

“…Furthermore, H 2 S was reported to have a neuroprotective effect against the cognitive diseases [38-40]. The proposed mechanisms underlying the protective effect of H 2 S involved oxidative stress [25] and autophagy [41]. …”

Section: Discussionmentioning

confidence: 99%

High Glucose Induces Mouse Mesangial Cell Overproliferation via Inhibition of Hydrogen Sulfide Synthesis in a TLR-4-Dependent Manner

Ding¹,

Chen²,

Li³

et al. 2017

Background/Aims: Overproliferation of mesangial cells was believed to play an important role in the progress of diabetic nephropathy, one of the primary complications of diabetes. Hydrogen sulfide (H₂S), a well-known and pungent gas with the distinctive smell of rotten eggs, was discovered to play a protective role in diabetic nephropathy. Methods: MTT assay was used to examine the viability of mesangial cells. Small interfering RNA was used to knock down the expression of TLR4 while specific inhibitor LY294002 to suppress the function of PI3K. H₂S generation rate was determined by a H₂S micro-respiration sensor. Results: Glucose of 25mM induced significant mesangial cells proliferation, which was accomplished by significantly inhibited endogenous H₂S synthesis. And exogenous H₂S treatment by NaHS markedly mitigated the overproliferation of mouse mesangial cells. Furthermore, it was found that H₂S deficiency could result in TLR4 activation. And H₂S supplementation remarkably inhibited TLR4 expression and curbed the mesangial cell overproliferation. Besides, PI3K/Akt pathway inhibition also significantly ameliorated the cell overproliferation. Conclusion: High glucose (HG) induces mouse mesangial cell overproliferation via inhibition of hydrogen sulfide synthesis in a TLR-4-dependent manner. And PI3K/Akt pathway might also play a vital part in the HG-induced mesangial cell overproliferation.

“…As a sensor of the cellular nutrient status, mTOR is inhibited during energy insufficiency and has been identified as a negative regulator of autophagy in mammalian cells [16, 19, 20]. AMP-activated protein kinase (AMPK) is a protein kinase member that can be activated by a reduction in the intracellular ATP/AMP ratio [21].…”

Section: Resultsmentioning

confidence: 99%

Shock Wave Therapy Promotes Cardiomyocyte Autophagy and Survival during Hypoxia

Shen

Liu³

et al. 2017

Background: Autophagy plays an important role in cardiovascular disease. Controversy still exists regarding the effect of autophagy on ischemic/hypoxic myocardium. Cardiac shock wave therapy (CSWT) is an effective alternative treatment for refractory ischemic heart disease. Whether CSWT can regulate cardiomyocyte autophagy under hypoxic conditions is not clear. We established a myocardial hypoxia model using the H9c2 cell line and performed shock waves (SWs) treatment to evaluate the effect of SW on autophagy. Methods: The H9c2 cells were incubated under hypoxic conditions, and SW treatment was then performed at energies of 0.02, 0.05, or 0.10 mJ/mm². The cell viability and intracellular ATP level were examined. Western blot analysis was used to assess the expression of LC3B, AMPK, mTOR, Beclin-1, Sirt1, and HIF-1α. Autophagic vacuoles were visualized by monodansylcadaverine staining. Results: After the 24-hour hypoxic period, cardiomyocyte viability and ATP levels were decreased and autophagy was significantly increased in H9c2 cells. SW treatment with an energy of 0.05 mJ/mm² significantly increased the cellular viability, ATP level, LC3B-II/I, and number of autophagic vacuoles. In addition, phosphorylated AMPK and Sirt1 were increased and phosphorylated mTOR and HIF-1α were decreased after SW treatment. Conclusion: SW treatment can potentially promote cardiomyocyte autophagy during hypoxia and protect cardiomyocyte function by regulating the AMPK/mTOR pathway.