Oxygen-Glucose-Deprivation/Reoxygenation-Induced Autophagic Cell Death Depends on JNK-Mediated Phosphorylation of Bcl-2

Jin Fan, Yuwen Liu, Jian Yin, Qingqing Li, Yiming Li, Jun Gu, Weihua Cai, Guoyong Yin
2016 Cellular Physiology and Biochemistry  
This is an Open Access article licensed under the terms of the Creative Commons Attribution-NonCommercial 3.0 Unported license (CC BY-NC) (www.karger.com/OA-license), applicable to the online version of the article only. Distribution permitted for non-commercial purposes only. Abstract Background/Aims: The purpose of this study was to investigate the role of autophagy in oxygen-glucose-deprivation/reoxygenation (OGD/R) injury in rat neurons. Methods and results: Cortical neurons were isolated
more » ... ons were isolated from Sprague-Dawley rats and identified by immunofluorescence. The cortical neurons were randomly assigned to one of four groups: control group (I), experimental group (OGD/R group, II), JNK inhibitor pretreatment group (III) and JNK inhibitor pretreatment + OGD/R group (IV). Neuronal cell viability significantly decreased after 6h and 12h of reoxygenation in Group IV (P < 0.05). Electron microscopy showed the presence of many autophagic vacuoles and the formation of autolysosomes in the neurons; the number of autophagic vacuoles decreased transiently at 6h, while a new autophagic flux and a large number of empty autophagic vacuoles were observed at 12h. In Group IV, a large number of autophagic vacuoles were present at 0.5h and 2h of reoxygenation, which gradually decreased with increasing reoxygenation time. No significant differences in the expression of the LC3II protein were detected between the Group II and IV prior to 6h of reoxygenation, and LC3II expression showed an overall rise-decline pattern. However, LC3II protein expression increased in Group II at 12h of reoxygenation, whereas a continuous decline was observed in Group IV. The levels of phosphorylated JNK and Bcl-2 and the expression of Beclin-1 increased gradually as the reoxygenation time going in Group II, whereas they increased at 12h of reoxygenation in Group IV (P < 0.05). In addition, progressive dissociation of the Bcl-2/Beclin-1 complex was observed in the Group II, while JNK inhibitor suppressed this dissociation. Conclusion: The regulation of the JNK/Bcl-2/Beclin-1 signaling pathway may be one of the mechanisms underlying the OGD/R-induced autophagic cell death of neurons. J. Fan and Y. Liu contributed equally to this work. group, and JNK activity and Bcl-2 expression increased with increasing reoxygenation time, while this effect was suppressed by JNK inhibitor treatment.
doi:10.1159/000443057 pmid:26938208 fatcat:smgpkqvcrrdujizkgpivjmrlou