17β-Estradiol and/or Estrogen Receptor β Attenuate the Autophagic and Apoptotic Effects Induced by Prolonged Hypoxia Through HIF-1α-Mediated BNIP3 and IGFBP-3 Signaling Blockage

Han

et al. 2016

Background/Aims: Cardiovascular disease is a growing major global public health problem. Necrosis is one of the main forms of cardiomyocyte death in heart disease. Oxidative stress is regarded as one of the key regulators of cardiac necrosis, which eventually leads to cardiovascular disease. Many pharmacological and in vitro studies have suggested that FGF-2 can act directly on cardiomyocytes to maintain the integrity and function of the myocardium and prevent damage during oxidative stress. However, the mechanisms by which FGF-2 rescues the myocardium from oxidative stress damage in cardiovascular disease remain unclear. The present study explored the protective effects of FGF-2 in the H₂O₂-induced necrosis of H9C2 cardiomyocytes as well as the possible signaling pathways involved. Methods: Necrosis of H9c2 cardiomyocytes was induced by H₂O₂ and assessed using a Cell Counting Kit-8 (CCK8) assay and flow cytometry analysis. The cells were pretreated with the PI3K/Akt inhibitor Wortmannin to investigate the possible involvement of the PI3K/Akt pathway in the protection by FGF-2. The levels of Akt, p-Akt, FoxO3a, p-FoxO3a, and BNIP3L were detected by Western blot. Chromatin immuno-precipitation (ChIP) analysis was used to test whether FoxO3a binds directly to the BNIP3L promoter region. A luciferase assay was used to study the effects of FoxO3a on BNIP3L gene promoter activity. Mitochondrial ΔΨM was quantified using tetramethylrhodamine methyl ester perchlorate (TMRM). The mitochondrial oxygen consumption rate (OCR) was assessed with a Seahorse XF24 Analyzer. Results: Treatment with H₂O₂ decreased the phosphorylation of Akt and FoxO3a, and it induced the nuclear localization of FoxO3a and the necrosis of H9c2 cells. These effects of H₂O₂ were abrogated by pretreatment with FGF-2. Furthermore, the protective effects of FGF-2 were abolished by the PI3K/Akt inhibitor Wortmannin. ChIP analyses indicated that FoxO3a binds directly to the BNIP3L promoter region. Using a luciferase assay, we further observed that FoxO3a increased BNIP3L gene promoter activity. As expected, overexpression of BNIP3L in H9C2 cardiomyoblast cells reduced the cardioprotection of FGF-2 in H₂O₂-induced necrosis and mitochondrial dysfunction. Conclusions: The present data suggest that FGF-2 protects against H₂O₂-induced necrosis of H9C2 cardiomyocytes via the activation of the PI3K/Akt/FoxO3a pathway. Moreover, the present results demonstrate that FoxO3a is an important transcription factor that acts by binding to the promoter and promoting the transcription of BNIP3L, and it contributes to the necrosis and mitochondrial dysfunction induced by H₂O₂ in H9c2 cardiomyoblast cells.

Section: Discussionmentioning

confidence: 99%

FGF-2 Transcriptionally Down-Regulates the Expression of BNIP3L via PI3K/Akt/FoxO3a Signaling and Inhibits Necrosis and Mitochondrial Dysfunction Induced by High Concentrations of Hydrogen Peroxide in H9c2 Cells

Han

et al. 2016

“…Accumulating lines of evidence have demonstrated that oxidative stress significantly modulates autophagy during cellular stress [18]. In 2009, Ju Huang found that NOX2 mediated autophagic activity in phagocytes [19].…”

Section: Discussionmentioning

confidence: 99%

Stachydrine Protects Against Pressure Overload-Induced Cardiac Hypertrophy by Suppressing Autophagy

Cao

Dong

et al. 2017

Background: Autophagy is required for the maintenance of cardiomyocyte homeostasis. However, excessive autophagy plays a maladaptive role in pressure overload-induced heart failure. To identify mechanisms by which Stachydrine inhibits pressure overload-induced cardiac hypertrophy, we determined inhibitory activities against activation of NADPH oxidase, reactive oxygen species(ROS) production and excessive activation of autophagy. Methods: Stachydrine was administered intragastrically to Wistar rats after Transverse aortic constriction(TAC) and H9c2 cells were treated with Stachydrine after Angiotension II stimulation. The activation of NADPH oxidase2 required the membrane translocation of p47phox and p67phox. Cell membrane fraction was isolated by ultracentrifuge in sucrose. The expression of p67phox, p47phox, gp91phox subunit in the cell membrane were determined by western blot. The combination of p67phox and gp91 phox subunit was detected by immunofluorescence staining. The expression of phosphorylated p47phox subunit was determined by western blot. The intracellular ROS were measured with DCF-DA fluoresence. The autophagic flux was measured by recording the fluorescence emission of the fusion protein mRFP-GFP-LC3 by dynamic live-cell imaging. Reuslts: We report here that stachydrine, a major constituent of Leonurus heterophyllus Sweet, inhibited AngII-induced excessive autophagy within H9c2 cells. Stachydrine blocked the over phosphorylation of the p47phox subunit, decreased the translocation of p47phox and p67phox to the membrane, inhibited the activity of NOX2, and reduced the generation of ROS. We also demonstrated that stachydrine ameliorated TAC-induced cardiac hypertrophy, dysfunction and excessive autophagy in vivo. Conclusions: Our study highlights the importance of regulating NOX2 when autophagy is obviously activated. By inhibiting NOX2, Stachydrine inhibits ROS production, thus exerting a remarkable activity of inhibiting hypertrophy, which could have considerable effect on clinical practice.

“…1A, the red fluorescent dots were gradually increased along with the treatment time of H/R and the eRFP-LC3 dot was obviously more in cells incubated with Rap than those of the control and cells incubated with 3-MA. To further confirm the autophagic activity, the LC3-I (16 kDa) to LC3-II (14 kDa) conversion [20][21][22][23] was checked through western blot analysis. As expected, Rap treatment induced a significant increase of LC3-II/LC3-I ratio in cells as compared with control and cells treated with 3-MA at any duration (P < 0.05; Fig.…”

Section: Effect Of 3-ma and Rap On Autophagy Formation After H/rmentioning

confidence: 99%

Autophagy Activation by Rapamycin Before Hypoxia-Reoxygenation Reduces Endoplasmic Reticulum Stress in Alveolar Epithelial Cells

Fan

Huang

et al. 2017

Background: To determine potential effects of autophagy activation on hypoxia-reoxygenation (H/R) induced damage of a rat alveolar epithelial cell line. Methods: CCL149 cells were subjected to autophagy agonist (rapamycin, Rap), autophagy inhibitor (3-methyladenine, 3-MA) or PBS for 1 h before H/R treatment for 2 h, 4 h and 6 h. The optimal concentration of Rap (150 nM, 200 nM and 250 nM) or 3-MA (5 mM, 10 mM and 15 mM) was obtained from MTT assay. Autophagy was determined by fluorescence microscopy of eRFP-LC3 positive cells, transmission electron microscopy of autophagosome, western blot of LC3, AMPK, Beclin-1, HDAC6 and p62 proteins. Endoplasmatic reticulum stress was indicated by detecting expressions of BIP, XBP-1 and CHOP via western blot. Results: Rap at concentration of 250 nM before H/R increased the autophagy formation with more eRFP-LC3 positive cells and higher expressions of LC3-II, Beclin-1, HDAC6 and p62, but lower expressions of BIP, XBP-1 and CHOP in H/R treated CCL149. This effect seemed to be still obvious after H/R exposure for 6 h. The contrary results were obtained by treatment with 5 mM 3-MA. Conclusion: Rap might be a promising agent before mechanical ventilation or reperfusion to prevent re-damage in hypoxia related lung diseases.